Table of Contents
From the Editors ......................................................................................................................................... 1
RERF NewsThe 39th Scientific Advisory Committee Meeting ................................................................................ 2
The Second Public Lecture Program Held in Hiroshima ...................................................................... 5
The Fourth Board of Directors Meeting Held in Hiroshima ................................................................. 6
Completed Transition to Public Interest Incorporated Foundation ....................................................... 6
Japan’s Ambassador to Iceland Visits RERF......................................................................................... 7
Visit to RERF by Two Ukraine Officials ............................................................................................... 7
U.S. TV Science Correspondent Visits RERF ....................................................................................... 8
RERF Chief Scientist Dispatched to Seminars in Hawaii on Medical Care of Atomic-bomb
Survivors............................................................................................................................................ 8
Staff News ............................................................................................................................................. 9
Visiting Student Researchers ............................................................................................................... 10
Conference and Workshop Reports
The Second Meeting of the Scientific and Ethics Committee for the Clinical Study of the F1
Offspring of A-bomb Survivors, by Waka Ohishi ........................................................................... 12
RERF International Workshop: Radiation Effects on Mutation in Somatic and Germline
Stem Cells, by Asao Noda ............................................................................................................... 13
Science Articles
Highlights of RERF Departments: Research Activities in the Department of Genetics,
by Yoshiaki Kodama and Jun-ichi Asakawa .................................................................................... 16
Highlights of RERF Departments: Research Activities in the Department ofRadiobiology/Molecular Epidemiology, by Yoichiro Kusunoki ..................................................... 26
Human Interest Notes
In Memoriam ....................................................................................................................................... 39
On the Occasion of My Mandatory Retirement, by Yoshiaki Kodama ............................................... 43
Taking Early Retirement, by Saeko Fujiwara...................................................................................... 44
Facts and Figures
Accession Number of Scientific Manuscripts Reaches 1,000 ............................................................. 45
Research Protocol and Recent Publications
Research Protocol Approved in November 2011–April 2012 ............................................................. 46
Recent Publications ............................................................................................................................. 46
Cover photograph: A related story on page 6

This newsletter is published by the Radiation Effects Research Foundation (RERF; formerly
the Atomic Bomb Casualty Commission), established in April 1975 as a private, nonprofit
Japanese foundation. It is supported by the government of Japan through its Ministry of Health,Labour and Welfare and by the United States through its Department of Energy (DOE), in partby DOE contract DE-HS0000031 with the National Academy of Sciences. RERF became apublic interest incorporated foundation on April 1, 2012.
RERF conducts research and studies—for peaceful purposes—on medical effects of radiation
and associated diseases in humans, with a view to contributing to maintenance of the health andwelfare of the atomic-bomb survivors and to enhancement of the health of all humankind.
Editor-in-Chief: Evan B. Douple, Associate Chief of ResearchTechnical Editor: Fumie Maruyama, Public Relations & Publications Office
Editorial Policy
Contributions to RERF Update receive editorial review only and do not receive scientific peer
review. The opinions expressed herein are those of the authors only and do not necessarily reflect
RERF policies or positions.
Contact: Mailing address: RERF Public Relations & Publications Office, 5-2 Hijiyama Park,
Minami-ku, Hiroshima 732-0815 Japan
Telephone: 81-82-261-3131; Facsimile: 81-82-263-7279
Internet: www.rerf.jp

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From the Editors

From the Editors
Konnichiwa (hello and good afternoon) andwelcome to RERF Update!
Over a year has passed since the 2011 Great East
Japan Earthquake and tsunami and in this issue you
will read that RERF scientists continue to provide
information regarding risks of long-term healtheffects following exposures to radiation based on
RERF’s studies of the health effects in the atomicbomb survivors. Inquiries regarding the potential
implications for health from the Fukushima accident have resulted in an enhanced RERF public
relations effort with information disseminated byour scientists through several venues including
RERF’s website, interviews with the news media,
public lectures, and training workshops for visiting
students, public health workers, and officials. Some
RERF scientists contribute by their membershipin a number of advisory groups. Those activities
are consistent with RERF’s qualifying as a public
interest incorporated foundation (PIIF) which did
occur when RERF registered as a PIIF on April 1,2012 (no fooling; see cover photo).
Although the winter was colder than normal andcontinued for what seemed to be an unusually longtime, eventually things returned closer to “normal”
at RERF. For example, the 39th Scientific Advisory
Committee (SAC) met to assess RERF’s progress,
and the research activities and accomplishments ofthe two departments that received focused SAC
review—Genetics and Radiobiology/Molecular
Epidemiology—are highlighted in overviews written by the respective department chiefs in this issue
along with the SAC’s report. And, although thesakura (cherry) blossoms were delayed due to thecool winter weather, eventually Hijiyama was aburst of flowers and color. The cheerful sounds ofohanami celebrations, which were conspicuously
missing or subdued last year, began to return to
Hijiyama (as shown in the photograph on this page)along with the distinctive and pleasant call of theuguisu (Japanese Nightingale).
Unfortunately, we must report that since the lastissue of Update, three of the most influential andimportant contributors to the scientific work of
ABCC and RERF have died; James F. Crow, Itsuzo
Shigematsu, and Seymour Jablon. Please take time
to read about the major impacts that each of thesethree men had on the Foundation.
Lastly, let me thank profusely Update’s Technical Editor, Yuko Ikawa, who retired at the mandatory retirement age in December 2011. Ms.
Ikawa joined RERF in April 1985 as an executive
secretary who supported the offices of the Chief ofSecretariat, Chairman, and Permanent Directors.
She was transferred to the Editorial and Publications Section of RERF in July 1999 and became
Section Chief in October of 2001. In January 2006,
the office was reorganized into the Public Relations and Publications Office. RERF Update had
been inaugurated in the spring of 1989 by Ms. BethMagura. In the spring of 2001, Ms. Ikawa became
involved in editing of Update and in the next year,
became the Technical Editor of Update which was
published once per year. I joined Ms. Ikawa inJanuary of 2008, and she and I have been working together to produce two issues per year sincethat time. She is well known for her attention todetail, hard work, dedicated service to RERF, andhigh productivity. Fortunately, shewill continue to work part-time at
RERF as an Adjunct Specialist so
will still be available to provide
assistance to me and her successor. The other fortunate thing isthat I get to introduce her successor, Fumie Maruyama, who wasrecruited as the new Technical
Editor. A long-time employee of
RERF, Ms. Maruyama had beenworking with me in the Office of
the Associate Chief of Research
since my arrival in 2008. She has
the attributes of a good editor, soin the photograph on the next page
I appear very confident as I’m
handing over the Technical Editor
reins!
We hope that you enjoy this,Maruyama-san’s first issue, andA group of people enjoying cherry blossoms on Hijiyama

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RERF Update Volume 23, Issue 1, 2012

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RERF News
don’t hesitate to let us know how we might improve
our reporting of RERF’s many activities. Mataoidekudasai (goodbye and please come again),

Evan B. Douple
Editor-in-Chief

Fumie Maruyama
Technical Editor

Transitioning of Update’s technical editors in the RERF’s
Japanese garden; from left, Yuko Ikawa (former), Evan B.
Douple, and Fumie Maruyama (current)

Report on the 39th Scientific Advisory Committee Meeting, 2012
The 39th Scientific Advisory Committee (SAC)
met from March 5–7, 2012 in Hiroshima, Japan toreview RERF’s scientific programs. It was cochaired by Kazuo Sakai and Sally Amundson.
Shunichi Yamashita, Vice President, Fukushima
Medical University, joined the SAC with the expiration of the term of Takashi Yanagawa. Three
additional experts were invited to be special councilors to assist the SAC in an in-depth review of the
Departments of Genetics and Radiobiology/Molecular Epidemiology (RME). They were Tetsuya
Ono of Tohoku University, Toshio Suda of Keio
University, and William Morgan of Pacific Northwest National Laborabory.
RERF Chairman Toshiteru Okubo provided awarm welcome to the SAC members and guests
and expressed how important the SAC’s work is tothe staff of the RERF. He also explained the basicsof the now-completed change of the Act of Endowment with RERF becoming a public interest incorporated foundation (PIIF).
Responses to last year’s SAC general recommendations and highlights of research accomplishments during 2011 were summarized by Vice
Chairman Roy E. Shore. In response to the 2011
SAC recommendations, we have streamlined theresearch protocol (RP) review process and are
employing a method to provide an early concept
review of potential RPs that helps focus andimprove them. Program-based structures have been
implemented to overlay departmental work so as tofacilitate thematic interdisciplinary research. The
programs pertain to radiation research in cancer,
circulatory disease, other noncancer endpoints (e.g.,cataract), immunologic effects, genetic (transgenReturn to Table of Contents

erational) effects, and dosimetry, plus the “platform
protocols” for the basic data collection and methodologic developments. A special RERF committee was created to review the status of information
technology at RERF and to develop guidance
regarding the needs for integrated databases ofresearch information and biospecimens. We areworking to strengthen our collaborations with various universities and to strengthen our fledgling
post-doctoral program. We also are working withdepartment chiefs and members to develop highquality publications on radiation-related healthassessments. The Committee on Biological Samples has been tasked to develop a plan to consolidate our biospecimen processing, storage, and integrated biosample database management.
Among the highlights of accomplishments during FY2011 were publications on a number of topics related to radiation risk, most especially a major
update of cancer and noncancer mortality in theLife Span Study (LSS) cohort. Other radiationrelated publications included findings regarding
risk of hemorrhagic stroke, risk of myelodysplastic
syndrome, levels of breast-cancer related hormones, various subtypes of lung cancer, chronic
kidney disease mortality, effects on age at menopause, and development of a new method to detectin vivo mutations associated with radiation damage
and genetic risk. Regarding radiation dosimetry, 14
papers from our international conference on RERF
organ/tissue dosimetry were published, as were
papers on A-bomb fallout exposures: a geospatial
analysis of cesium-137 in Hiroshima soil samples,and ESR (electron spin resonance) tooth enamelmeasurements of distal A-bomb survivors in relaRERF Update Volume 23, Issue 1, 2012

RERF Newstion to fallout exposure.
RERF scientists have organized or participatedin a number of radiation-related activities to communicate our findings or conduct training. Invitedlectures were given at the International Congress on
Radiation Research by Chief Scientist Kazunori
Kodama, Epidemiology Department Chief Kotaro
Ozasa, and Associate Chief of Research Evan
B. Douple. Chief Scientist Nori Nakamura is amember of the ICRP (International Commission
on Radiological Protection) and Dr. Kodama of
UNSCEAR (United Nations Scientific Committee
on the Effects of Atomic Radiation). In January
2012 we conducted an international workshop on
radiation and stem cell effects. During FY2011 we
also conducted a radiation epidemiological training
workshop for biologists from a number of institutions, and had over 180 trainees who spent froma day to over a month receiving training at RERF.
We also have intensified our efforts to provide
press conferences and press releases regarding new
research findings.
Scientists at RERF have been active participantsin Fukushima-related matters. We dispatchedexperts to train local public-health personnel inmaking personal radiation measurements, quickly
developed a Fukushima-oriented webpage withinformation and FAQs about radiation effects, andprovided expertise for a biological dosimetry working group. RERF members are continuing to provide advice to the Japanese central government andlocal governments regarding possible health risks
and to the Fukushima long-term epidemiologicalstudy team regarding study planning, health assessments, and biological measurements. RERF members also are serving on Fukushima risk-assessment
committees of UNSCEAR and the WHO (World
Health Organization).
The SAC believes “that the RERF is the preeminent leader in radiation risk research in theworld and has the expertise, populations, and data
sets to conduct [unique] fruitful investigations…”
They appreciated the sustained support of theJapanese Ministry of Health, Labour and Welfare(MHLW), the U.S. Department of Energy (DOE),
and the U.S. National Academy of Sciences (NAS).
They also stated “The Fukushima disaster dramatically highlights the importance of the RERF mission; a mission made only more crucial byincreased worldwide power needs, increased use of
medical radiation, and increased threats of radiological or nuclear terrorism.”
The general recommendations by the SAC
included the following:• RPs “should address clearly articulated testable hypotheses that contribute to the overall
goals of RERF.” In adopting new technologies
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3or systems, “care should be taken that such
experiments are designed to address high priority questions in an appropriate way.” A
transparent system should be in place toensure that biosamples are used to address themost important biological questions.
• Interactive discussions in evaluating RPs canbe used as an opportunity for education andtraining of young investigators.
• The efforts of RERF in support of activities
related to Fukushima are an ideal example ofdelivery of a valuable RERF “product,” thetransfer of RERF scientific and methodological knowledge to a pressing public concern.
• RERF must continue to give the highest priority to the reassignment and renovation of
space for the secure and accessible storage ofthe biological samples, and to the development of a database providing sample identification, location, and other information.
• The SAC continues to strongly recommendthat the varied databases of participant information and biological samples be integrated
into a central database for the use by all
departments. Access to the complete data on
every subject is crucial to RERF’s central
mission.
• Investigators should not depend solely uponinternal research funding, and should continue to be encouraged to obtain competitive
external grants.
• The SAC appreciates the efforts made toresolve the issues surrounding the potential
impact of “black rain” fallout on dosimetry
and health outcomes in the face of current
public concern. We understand that full resolution of these questions may not be possible
due to many uncertainties in the data, but weare confident that RERF is undertaking appropriate analyses where possible and encourage
publication of the findings.
• To meet the bioinformatics needs of highthroughput technologies in basic science andepidemiology, the Statistics Department
should explore the possibility of developing
links with outside collaborators before initiating any bioinformatics recruitment.
• The SAC commends the ongoing seminars
and interactions between and within departments but also encourages the development ofseveral focused research discussion groups tohelp reduce the fragmentation of research
effort.
• The ongoing collaborations with externalorganizations are commendable, but the SAC
suggests that these and new collaborations
should seek to include some level of RERF
financial support, such as through subconRERF Update Volume 23, Issue 1, 2012

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RERF News
tracts.
• More high quality publications are essential
for the continued success of RERF.
Highlights of some of the recommendations forindividual departments or offices are:
• Some standardization of protocols should be
developed for archival tissues. This includes
detailed protocols for preparation of samples
for analysis as well as quality control standards.
• The images of somatic and germ line mutations in vivo or in explants from the GFPmutant mouse are stunning and spectacular.
The targeted issue to address with those studies seems to be germ cell mutation, which is aneglected facet in estimating the genetic doubling doses of radiation.
• The atomic-bomb survivor studies on cardiovascular disease (CVD) incidence and on theassociation between chronic kidney disease
and CVD risk factors should be strengthened
and summarized as full papers. A careful
attempt should be made to detect the possible
role of rare diseases in the etiology of themore commonly appearing disease phenotypes.
• As the younger epidemiologic and clinicalcohorts have fewer “events” and need to befollowed for a long time, efforts need to be
implemented to maintain high participation
and reduce loss to follow up. Also, efforts toobtain up-to-date denominators for population
studies of cancer incidence should continue.
• The Statistics Department has been evaluating
the basic LSS dosimetry with several publications and extensive collaborations. The
department is encouraged to quickly make theneeded adjustments to the DS02 system based
upon the Epidemiology Department’s re-evaluation of the original maps and aerial photo-graphs.
• Opportunities could be sought to reach students at local universities and even secondary
schools with the grandeur and excitement ofradiation research. Public lectures for adultlearners might be offered in other major cities
beside Hiroshima and Nagasaki.
In summary, the SAC highlighted the uniquerole of RERF in informing the world about radiation effects, and they called for additional attention
to research priorities, careful development ofresearch hypotheses and focus, integrated databases, and publication productivity.
RERF Scientific Advisors
Dr. Kazuo Sakai, Co-chairperson, Director, Research Center for Radiation Protection, National Institute of Radiological Sciences
Dr. Sally A. Amundson, Co-chairperson, Associate Professor of Radiation Oncology, Center forRadiological Research, Columbia University
Medical Center
Dr. Katsushi Tokunaga, Professor, Department of
Human Genetics, Division of International
Health, Graduate School of Medicine, The University of Tokyo
Dr. Kiyoshi Miyagawa, Professor, Laboratory of
Molecular Radiology, Center for Disease Biology and Medicine, Graduate School of Medicine, The University of Tokyo
Dr. Kazuo Tajima, Director, Aichi Cancer Center
Research Institute
Dr. Shunichi Yamashita, Vice President, Fukushima
Medical University
Dr. Marianne Berwick, Professor and Chief, Division of Epidemiology, Associate Director, Population Sciences, University of New Mexico
Dr. John J. Mulvihill, Children’s Medical Research Institute/Kimberly V. Talley Chair in

Participants of the 39th Scientific Advisory Committee meeting held at Hiroshima RERF
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RERF Update Volume 23, Issue 1, 2012

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RERF News
Genetics; Professor of Pediatrics; Head, Section of Genetics, University of Oklahoma
Health Sciences Center
Dr. Michael N. Cornforth, Professor and Directorof Biology Division, Department of Radiation
Oncology, University of Texas Medical Branch(Absent)
Dr. David G. Hoel, Distinguished University Professor, Department of Medicine, Medical University of South Carolina and Principal Scientist, Exponent Inc.

Special Advisors
Dr. Tetsuya Ono, Professor, Division of Genome
and Radiation Biology, Department of Cell
Biology, Graduate School of Medical Sciences,
Tohoku University
Dr. Toshio Suda, Professor, Department of Cell
Differentiation, The Sakaguchi Laboratory ofDevelopmental Biology, School of Medicine,
Keio University
Dr. William F. Morgan, Director of Radiation
Biology and Biophysics, Biological Sciences
Division, Pacific Northwest National Laboratory

Second Public Lecture Program Held in Hiroshima
On December 10, 2011, RERF held its second
public lecture program in the Memorial Hall inthe basement of the Hiroshima Peace Memorial
Museum’s East Building, from 14:00 to 16:30. The
objectives of this lecture program were to explain
in a straightforward manner to the general public,
including A-bomb survivors, about RERF’s longyears of research findings, health effects of radiation, and a topic of increasing interest following
the Tokyo Electric Power Company’s Fukushima
Dai-ichi nuclear power plant crisis in March 2011.
An additional objective was to provide an opportunity for the public to communicate with RERF.
About 200 citizens participated in the lecture, aprogram that was initiated last year.
At the beginning of the program, following
opening remarks by Chairman Toshiteru Okubo,
Mr. Sunao Tsuboi, President of the Hiroshima
Prefectural Confederation of A-bomb Sufferers
Organizations and the honored invited guest of the
program, extended his greetings. Two lectures followed. First, Chief Scientist Nori Nakamura spokeon “Thinking about low-dose radiation exposure,”
explaining cancer risks from exposure to low-doseradiation and chronic radiation exposure, the typesof radiation exposures typically seen in Fukushima,based on results from epidemiological studies ofA-bomb survivors. Next, Genetics Department
Assistant Chief Asao Noda, in his lecture titled“Methods for radiation dose assessment,” briefed
the audience on the basics of radiation and methods

Return to Table of Contentsof radiation dose measurement.
Following the lectures, Dr. Hiroo Dohy, thenPresident of the Hiroshima Red Cross Hospital& Atomic-bomb Survivors Hospital and of theHiroshima International Council for Health Careof the Radiation-exposed (HICARE), gave special remarks as well as a general overview of thelectures. In the question-and-answer session that
followed, so many questions were collected byquestionnaire from the audience after each of thelectures that not all of them could be responded toin the time available. Several audience members
remained in the hall eagerly asking questions evenafter the close of the lecture.

Assistant Department Chief of Genetics Asao Noda givinga lecture during the second public lecture program

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RERF News

Fourth Meeting of the RERF Board of Directors Held in Hiroshima
Since RERF’s transition of status to an exceptional incorporated foundation with councilors in
April 2011, the RERF Board of Councilors has
replaced the Board of Directors (BOD) as the highest decision-making body at RERF. The BOD haschanged its structure and functions, and its meetings are now attended by resident Directors andAuditors. Four such meetings were held during
FY2011.
The fourth meeting of the BOD was held at theHiroshima Laboratory on March 9, 2012. With Mr.
David Williams joining via teleconference from his
office in South Carolina, USA, all Directors andAuditors attended the meeting.
Dr. Toshiteru Okubo reported on the Directors’
job performance and significant personnel matters.
The BOD then deliberated and unanimously
approved the activities plans and budget estimatesfor FY2012, the first fiscal year after RERF’s transition to a public interest incorporated foundation(PIIF; see the following article). In addition, there
were reports on the status of progress in the PIIF
transition process and on RERF’s responses to
Deloitte Touche Tohmatsu(RERF’s external
auditor)’s internal controls review report, as well as
finalization of the dates and venue for the second

meeting of the Board of Councilors.
Participants
Directors:
Dr. Toshiteru Okubo, Chairman (Representative
Director)Dr. Roy E. Shore, Vice Chairman and Executive
Director
Mr. Takanobu Teramoto, Executive Director
Auditors:
Mr. Takashi Kohno, Hiroshima General Law/
Accounting Office (CPA/licensed tax accountant, Takashi Kohno Office)Mr. David Williams, Senior Financial Advisor,
National Academy of Sciences
RERF Attendees:
Dr. Evan B. Douple, Associate Chief of Research
Dr. Nori Nakamura, Chief Scientist
Dr. Kazunori Kodama, Chief Scientist
Mr. Eiji Akimoto, Chief of Secretariat
Mr. Douglas C. Solvie, Associate Chief of Secretariat

Completed Transition to Public Interest Incorporated Foundation
After becoming an exceptional incorporated
foundation with councilors in April 2011, a resolution required to file for authorization of RERF’s
change of status to a public interest incorporated
foundation (PIIF) was adopted at the June 2011
Board of Directors and Board of Councilors meetings. RERF filed an application for the said transition with Japan’s Prime Minister on August 31,
2011. Following review of the application by the
Cabinet Office’s Public Interest Corporation Commission, a certificate of transition authorization
was granted by the Prime Minister on March 22,
2012. RERF was registered as a PIIF on April 1,2012 (Sunday).
Even after transition to PIIF status, the organiza-

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tion’s English name (and abbreviation)—the Radiation Effects Research Foundation (RERF)—will
not change. Under the new designation, what wasformerly called the Board of Directors is replacedby the Board of Councilors. The new Board of
Directors now includes Toshiteru Okubo, Roy E.
Shore, and Takanobu Teramoto. What had been the
Scientific Council is now called the Scientific
Advisory Committee.
See the cover photograph: RERF’s new sign with the official
Japanese name “Public Interest Incorporated Foundation”
on it. Shown in the photograph are Chairman Toshiteru
Okubo (right) and Chief of Secretariat Eiji Akimoto.

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RERF News

Japan’s Ambassador to Iceland Masayuki Takashima Visits RERF
On January 13, Japan’s Ambassador to Iceland
Masayuki Takashima paid a visit to RERF’s
Hiroshima Laboratory. Ambassador Takashima
spent two days in Hiroshima with the aim of studying issues involving peace in the city and touring
the Hiroshima Peace Memorial Museum and otherpeace-related facilities as well as RERF. At the laboratory, Chairman Toshiteru Okubo and Vice Chairman Roy E. Shore provided Ambassador Takashima
with a brief overview of RERF and an outline of
the foundation’s research efforts. The Ambassador
was then led on a tour of the facilities by RERF’s
Directors, who explained the organization’s biosample storage facilities and permanent exhibitions.

Ambassador Masayuki Takashima (far left) being briefed on
RERF and its research efforts

Visit to RERF by Two Ukraine Officials
On 24 February, two officials from Ukraine visited RERF. Dr. Dimitry Anatolijovich Bazyka is the
Director-General and Head of the Department ofClinical Immunology in the Research Centre for
Radiation Medicine of the National Academy ofMedical Sciences of Ukraine. He was accompanied
by Dr. Valery Alexandrovich Kashparov, Directorof the Ukraine Institute of Agricultural Radiologyof the National University of Life and Environmental Sciences of Ukraine. This was their first visit to
RERF and they included their stop in Hiroshima
after a visit to Fukushima.
The two visitors received greetings from Chairman Toshiteru Okubo. Vice Chairman Roy E.
Shore then explained the history of ABCC and
RERF and described the current foundation, itscohorts, funding support, facilities and staff, andthe focus of its research. He proceeded to review
the highlights of RERF’s most recent findings,
especially focusing on the studies of the Life Span
Study and Adult Health Study and the work of the
Departments of Clinical Studies, Epidemiology,
and Statistics. Associate Chief of Research, Evan
B. Douple concluded RERF’s presentation with a
discussion of RERF’s basic science research and areview of the activities underway in the Department of Genetics and the Department of Radiobiology/Molecular Epidemiology (RME). He emphasized that the basic science research at RERF
explores mechanisms responsible for radiationinduced health effects observed in humans, conducts experiments in model systems or in biosamples from humans that cannot be conducted directlyin humans, and identifies radiation effects that
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might be future epidemiological and clinical studies in humans. All of the previously mentioned
studies are conducted within the mission of RERF.
Dr. Bazyka then described the composition andresearch activities underway at the Research Centre
for Radiation Medicine in Kiev, Ukraine. He summarized the results of the studies of the Chernobyl
clean-up worker cohorts conducted by the research
center and described the studies’ biosample
resources and available dosimetry information.
This was followed by an exchange of opinions
regarding the findings from our two institutions
obtained studying two different populations ofradiation-exposed victims. The visitors presented
RERF scientists a copy of the 2011 book, Health
Effects of the Chernobyl Accident: A Quarter ofCentury Aftermath, for which Dr. Bazyka served as
one of the editors-in-chief.

Dr. Dimitry Anatolijovich Bazyka (left) and Dr. Valery
Alexandrovich Kashparov

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RERF NewsAt the conclusion of the discussions, the guests
were led on a tour of the RERF facilities by Drs.
Shore and Douple. Being an immunologist, Dr.
Bazyka was especially interested in the cell-sorting
facilities of the RME Department and the storageof cells in the deep freezers and liquid nitrogentanks. The tour also included a visit with Dr.
Kotaro Ozasa, Chief of the Department of Epidemiology and Dr. Yoshiaki Kodama, Chief of the
Department of Genetics.

U.S. TV Science Correspondent Visits RERF
As the March 11 anniversary of the Fukushima
nuclear reactor accident approached, many foreign
reporters returned to Japan to prepare stories on
the status of the recovery. On February 17, Miles
O’Brien, science correspondent for the U.S. Public
Broadcasting Service (PBS), visited RERF after his
trip to Fukushima, where he had been documenting
the clean-up and scientists were deciding whether
the residual radiation in the affected area could
cause harmful health effects. He spoke with RERF
scientists and was given a tour of RERF facilities. His story, “Near Fukushima, a Big ‘Guessing
Game’ Over Radiation’s Long-Term Risks,” wasaired on prime-time U.S. TV on the PBS NewsHour March 9, 2012. In the program Mr. O’Briensaid, “Given their [Japan’s] history, they do nothave to look far to get the most accurate scientific
data on radiation exposure and its long-term effects
on human beings. After all, the atomic age began
here. I went to Hiroshima to learn more about
the famous Radiation Effects Research Foundation.” As of this printing, the archived footage wasavailable at:
http://www.pbs.org/newshour/bb/science/jan-june12/
fukushima_03-09.html

PBS correspondent Miles O’Brien (left) being shown theliquid nitrogen tanks containing RERF’s important biosamples by Evan B. Douple, Associate Chief of Research

RERF Chief Scientist Dispatched to Seminars in Hawaii
on Medical Care of Atomic-bomb Survivors
RERF Chief Scientist Kazunori Kodama wasdispatched to deliver three seminars in Hawaii, theU.S., hosted by the Hiroshima International Council for Health Care of the Radiation-exposed(HICARE). The seminars, intended for physicians,
medical students, A-bomb survivors, and the general public in Hawaii, were held on February 23
and 24. It was the third HICARE seminar series
held overseas, following others held in the continental U.S. and Brazil. The objectives were to help
deepen understanding of A-bomb survivor medicalcare and to establish collaborative relationships
with local medical specialists. With the Fukushima
Dai-ichi nuclear power plant accident as a backdrop, Hiroshima’s radiation emergency medical
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Dr. Kazunori Kodama delivering seminars in Hawaii on
medical care of A-bomb survivors

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RERF News
care system and its experiences in radiation emergency support were also discussed.
In addition to Dr. Kodama, Dr. Hiroo Dohy,
then President of HICARE and of the Hiroshima

Red Cross Hospital & Atomic-bomb Survivors
Hospital, and Dr. Koichi Tanigawa, Vice Presidentof the Hiroshima University Hospital, were also
dispatched to the seminars.

Staff News
Yoshiaki Kodama, Chief of the Department of
Genetics, retired under the mandatory age limit on
December 31, 2011. He was reappointed as chiefof the same department on January 1, 2012. On
January 1, Eric J. Grant, Senior Scientist in the
Department of Epidemiology, and Ayumi Hida,
Chief of the Division of Medicine in the Department of Clinical Studies in Nagasaki, were promoted to the position of assistant chief of theirrespective departments.
In Japan, March 31 is the last day of the fiscal
year, and the new fiscal year starts on April 1 formost organizations, including schools and companies. At RERF, Saeko Fujiwara, Chief of the
Department of Clinical Studies, and AkihikoSuyama, Chief of the Department of Epidemiology in Nagasaki, resigned under the early retirement system on March 31, 2012. On April 1, Dr.
Fujiwara assumed her duties as Vice Director of the
Health Management and Promotion Center at theHiroshima Atomic Bomb Casualty Council. Dr.
Suyama got a fresh start in April as an internist at
the Osaka Saiseikai Izuo Hospital. Waka Ohishi,
Assistant Chief of the Department of Clinical Studies in Hiroshima, concurrently serves as acting
department chief. Dr. Fujiwara was appointed consultant of the same department in May and is
expected to continue contributing to RERF. Kotaro
Ozasa, Chief of the Department of Epidemiology
in Hiroshima, will concurrently serve as Chief of
the Nagasaki Epidemiology Department for thetime being.
Truong-Min Pham, Postdoctoral Scientist in
the Department of Epidemiology, and Robert D.
Abbott, Senior Scientist in the Department of Statistics, left RERF on March 30 and May 9, respectively. Dr. Pham moved to Toronto, Canada. Dr.
Abbott returned to the United States to assume his
previous position as professor of statistics at the
University of Virginia. It is unfortunate that RERF
lost four research scientists this spring. However,on April 1, Eiji Katsurada was hired by the Division of Health Examinations at the Department ofClinical Studies in Hiroshima and Keiko Ueda by
the Division of Clinical Laboratories at the samedepartment. The two research scientists newly
hired by RERF introduce themselves in the followReturn to Table of Contents

ing section.
At RERF, employees who have worked for 10,
20, and 30 years are commended for long service
in April every year. In 2012, four employees werecommended for 30 years of service, 14 employees
for 20 years, and three employees for 10 years,
respectively. Among them, Masataka Taga,
Research Scientist of the Cell Biology Laboratory,
Department of Radiobiology/Molecular Epidemiology, and Kanya Hamasaki, Research Scientistof the Cytogenetics Laboratory, Department of
Genetics, were commended for 10 years of service.
In Nagasaki, three employees were commended for
30 years of service, three for 20 years, and two for
10 years, respectively.
Eiji Katsurada, M.D.
I have been given the honorof taking a position at the
Department of Clinical Studies (Hiroshima) thanks to the
support of Professor Nobuoki
Kohno of the Department ofInternal Medicine 2 (formerlycomposed of the groups ofrespiratory diseases, diabetes,
Eiji Katsurada
circulatory diseases, and kidney diseases), Hiroshima University. I graduatedfrom the Hiroshima University Faculty of Medicine, like other physicians at RERF’s Departmentof Clinical Studies. As a college student, I would
often go on trips to various countries in East, South,and Southeast Asia by myself while busily working
part-time. After graduating from the university, I
served as a clinician of internal medicine in various
areas in Hiroshima prefecture for 15 years, working day and night (including as an on-duty emergency physician). I was fortunate to be supportedby the staff at each workplace, and my clinicalexperience gained through contact with many
patients has been meaningful and precious to me.
I was mainly involved in measures to combat community-acquired infections (common infectious
diseases) and severe or chronic infections, as wellas treatment of lifestyle diseases including hypertension, mild angina, arrhythmia, diabetes, abnormal lipid metabolism, early detection of malignant
RERF Update Volume 23, Issue 1, 2012

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RERF News
neoplasms, and prevention of arteriosclerotic(cardiovascular) diseases, focusing on anti-obesity
initiatives and smoking-cessation advice, among
other activities. I am certain that such experience
will prove useful in health examination activities at
RERF. Significant advances have been made in thefield of drug therapy over recent years such as with
ARB/ACE antihypertensive medication (discovery of the renin-angiotensin-aldosterone system),statins (used to lower cholesterol), and the diabetes
medication “Metformin.” I have realized from myexperience, however, that diet and exercise are evenmore important. For health reasons, I myself have
reduced my sodium intake and continue an exercise
regimen that includes biking. I also would like to
add that I am qualified as a care manager.
Even though I try to catch up on the news tounderstand what has happened since the accident at
the Fukushima Dai-ichi nuclear power plant, I
never dreamed of being able to engage in researchat RERF, the principal research institute of radiation health effects, an opportunity for which I feel
truly honored. My immediate goal is to correctly
understand the research results obtained at RERF
thus far, since I am still new and have much tolearn. Your support would be greatly appreciated.
Keiko Ueda, M.D., Ph.D.
Greetings to the staff of
RERF. I am Dr. Keiko Ueda,
and I joined the Division ofClinical Laboratories of the
Department of Clinical Studies as a research scientist on
April 1 this year.
Let me briefly tell you mycareer history. After graduatKeiko Ueda
ing from the Hiroshima University Faculty of Medicine in 1998, I worked
at the Hiroshima University Hospital and theHiroshima Red Cross Hospital & Atomic-bomb
Survivors Hospital as an internal medicine resident. I then was employed at the First Department
of Internal Medicine, Faculty of Medicine (pres-ently the Department of Medicine and Molecular
Science at the Hiroshima University Graduate
School of Biomedical Sciences). Subsequently,
after working at the Division of Gastroenterology,
Department of Internal Medicine, Chugoku Rousai
Hospital, for three years, I entered the Hiroshima
University Graduate School, where I pursued myresearch interest of investigating possible association between non-alcoholic steatohepatitis (NASH)
and impaired glucose tolerance. To this end, I
performed mainly in vitro experiments, culturing
hepatic stellate cells (HSC), which play a central
role in liver fibrosis and inflammation, and adding
advanced glycation end products (AGE) to suchcells to examine HSC activation. After receiving
my Ph.D., I worked at the Department of Hepatology, Hiroshima Red Cross Hospital & Atomicbomb Survivors Hospital, for three years. I thentook one year off last year to concentrate on raising
my child, and was offered the chance to work at
RERF.
My image of RERF comprised merely somebuildings I used to see along a running course usedby the university sports team I was on, a memorythat reminded me of the tough training I underwent
as a university student. I had no connection with
RERF nor expected to work here or be engaged inresearch ever again. My recent career involved
working as a clinician specialized mainly in liverdiseases. The life in research that I will experienceat RERF is certain to be quite different from myclinical work, and thus I have mixed feelings ofboth hope and anxiety. Last year, I gave birth to adaughter, and this first experience at childrearing
took all my time. This year, as I have become more
comfortable with childrearing over the past 12
months, I plan to restore my strength while taking
up tennis as a hobby and start working on radiation
effects studies with new aspirations. Having said
that, I still know almost nothing about RERF andwill have to ask for help from the staff of various
departments and sections. I look to all of you foryour guidance and support.

Visiting Student Researchers
Dr. Wong Kit Fai, a hematologist working forthe Department of Pathology, Queen Elizabeth
Hospital in Hong Kong, underwent training forbiological dose estimation at the Cytogenetics
Laboratory of the RERF Department of Genetics,
during the period from December 5, 2011 throughDecember 16 of that year. Even though the Queen
Return to Table of Contents

Elizabeth Hospital plans to establish a biologicaldose estimation laboratory in preparation for possible radiation accidents, there was no staff member
who had experience in this field of research. Therefore, the objective of Dr. Wong’s training at RERF
was to learn about methods of chromosome analysis best suited for biological dose estimation.
RERF Update Volume 23, Issue 1, 2012

RERF News
Furthermore, Ms. Hye-Jin Shin, a researcher at
the National Cancer Center (NCC), Korea, and Mr.
Georgijs Moisejevs, a laboratory assistant andmedical student at the Laboratory of Biochemistry,
Riga Stradins University, Latvia, underwent training at the RERF Department of Radiobiology/
Molecular Epidemiology during the period fromJanuary 5, 2012 through February 24 of the same
year. The following are self-introductions of Ms.
Shin and Mr. Moisejevs and their remarks about
experiences at RERF.

Hye-Jin Shin
I am from Seoul, Korea, where I earned Bachelor of Science and Master of Science degrees in
Genetic Engineering from Sungkyunkwan University. I am now working at the Radiation Medicine
Branch in the National Cancer Center (NCC),
Korea as a molecular biologist conducting basic
research related to radiation and molecular oncology.
Until 10 years ago, I often considered that Japanis so close, yet so far away. However, nowadays, I
feel more familiar with, and closer to, Japan as aresult of the active cultural exchanges between thetwo countries. And I often thought of a journey toJapan during the summer vacation season. Just intime, I was offered participation in the RERF International Exchange Program from my institution
and I was able to come here as a trainee. I’d like toexpress my thanks to RERF for offering me thesewonderful opportunities to share research experiences accumulated by RERF scientists over several
years as well as to experience Japan’s unique culture.
While at RERF I was trained for two months in
the Department of Radiobiology/Molecular Epidemiology (RME) to measure intracellular andplasma ROS (reactive oxygen species) levels inregard to investigating the immune function, as

Georgijs Moisejevs (left) and Hye-Jin Shin (right) with Dr.
Tomonori Hayashi (center) at the Immunology Laboratory

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11well as to quantify DNA methylation for analysis
of epigenetic status. In addition, I was able to conduct HLA (human leukocyte antigen) genotyping
and SNP (single nucleotide polymorphism) assays
with genomic DNA samples from cervical cancer
patients of the NCC, Korea, advised and assisted
by Dr. Tomonori Hayashi and the staff in RERF’s
Immunology Laboratory.
I think that the training in RERF will give me
several good ideas for my future studies. Onceagain, I want to convey gratitude to all of the RME
staff and I’ll never forget my valuable experience
here in RERF.

Georgijs Moisejevs
I am in my last year as a medical student at Riga
Stradins University, Latvia. In addition, I haveworked as a laboratory assistant almost for five
years in my host university’s Laboratory of Biochemistry where I studied redox processes. As iswell known, our area in 1986 experienced theChernobyl nuclear power plant accident. Many
people were exposed to the radiation, including
several people from Latvia, who worked as liquidators or clean-up workers during the disaster. My
laboratory, in collaboration with many institutions,participated in the health-effect investigations of
those people.
Even now when the world is peacefull, people
still need to conduct research on radiation effects,
because humanity is using nuclear power to produce energy and no one knows when some kind of
accident may appear, such as the Fukushima disaster one year ago.
For me it was a great opportunity to participate
in this kind of scientific exchange program at the
RERF’s Radiobiology/Molecular Epidemiology
Department (RME). During my stay here, I spent a
lot of time with my supervisor, Dr. Tomonori
Hayashi, conducting experiments related to radiation-induced apoptosis. It was very interesting tolearn new methods that could be used in my laboratory.
After graduating from the medical university, I
want to become a medical oncologist and conduct
research in the field of cancer biology. So theknowledge taken from my RERF experience will
help me in my future career. In addition, I madeseveral very useful contacts with the Japanese scientists.
I would like to thank my supervisor, Dr. Hayashi,
as well as all colleagues from RME, who were suchexcellent hosts and who gave me excellent explanations, training, and practical skills. Thank you!

RERF Update Volume 23, Issue 1, 2012

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Conference and Workshop Reports

Second Meeting of the Scientific and Ethics Committee for theClinical Study of the F1 Offspring of A-bomb Survivors
Waka Ohishi, Acting Chief
Department of Clinical Studies, Hiroshima
The second meeting of the Scientific and Ethics
Committee for the Clinical Study of the F1 Offspring of A-bomb Survivors was held at Hiroshima
RERF’s Auditorium on January 12, 2012. The
meeting included reports on the progress of thelongitudinal clinical study of the F1 offspring of
A-bomb survivors and on the analysis of the prevalence of individual multifactorial diseases among
the F1 offspring of A-bomb survivors, with discussion taking place regarding the draft of revisions to
the written explanation and consent form used at
the clinical examinations.
The objective of the original cross-sectional
health effects study of the children of A-bomb survivors, conducted from 2000 through 2006, was tostudy the association between parental radiation
exposure and the prevalence of multifactorial diseases among their offspring, based on a mail survey(of 24,673 persons) and health examinations(11,951 persons). As a result of the study’s analysis
combining six multifactorial diseases (hypertension, hypercholesterolemia, diabetes mellitus,
angina pectoris, myocardial infarction, and stroke),no evidence was observed indicating that risk ofthese diseases increased with parental radiation
exposure. The average age of the participants in theoriginal study was approximately 49 years, a relatively young age at which disease prevalence typically just begins to increase. In addition, existenceof selection bias in terms of who decided to participate in the health examinations could not be denied
in the study. Therefore, changing from a cross-sectional to a longitudinal study was recommended asnecessary by the then Joint Scientific and Ethics
Committee for the Health Effects Study of theChildren of A-bomb Survivors, the ScientificCouncil, and the Senior Review Panel.
Based on these recommendations, Vice Chairman Roy E. Shore, Executive Director Takanobu
Teramoto, Chief Scientist Kazunori Kodama,Chief Scientist Nori Nakamura, and the F1 Clinical Study Working Group, consisting of ClinicalStudies Department Chief Saeko Fujiwara andother department chiefs and research scientists, met
repeatedly to review the issue. In addition, at its
first meeting held on July 7, 2010, the Scientificand Ethics Committee for the Clinical Study of the
F1 Offspring of A-bomb Survivors deliberated andapproved the research protocol for the “Longitudinal Clinical Study of the F1 Offspring of A-bomb
Return to Table of Contents

Survivors,” for which I served as principal investigator. Preparations for this longitudinal clinicalstudy’s implementation were made by gaining support from all the sections in the Clinical Studies
Departments in Hiroshima and Nagasaki, and otherdepartments including Epidemiology and Information Technology, and on November 24, 2010, thestudy was initiated involving approximately 12,000
participants.
The agenda of the second meeting started with
RERF Chairman Toshiteru Okubo’s opening
remarks and introduction of the committee members, and after Committee Chairman Tadao
Shimao’s greetings, I reported on the progress during the one year since initiation of the longitudinal
study. Chairman Shimao then moderated a Q and A
session, and in terms of the issue of the participation rate of 70%, including the number of expectedparticipants, as opposed to the targeted rate of 80%,the committee members provided a number of
meaningful proposals to improve participation.
Associate Senior Scientist Yoshimi Tatsukawa of
the Department of Clinical Studies next reported
on the latest analysis of individual multifactorialdiseases employing data from the original study, as
follows: “No evidence was observed for theincrease of disease risk related to parental radiation
exposure, but it is necessary to continue the study
by following the participants until they become
elderly, when development of multifactorial diseases tends to increase.” Regarding ethical mattersfor deliberation, I explained the draft revisions tothe consent forms and explanatory notes on clinicalexaminations and storage/use of biological samples, and following a Q and A session moderated

The second meeting of the Scientific and Ethics Committee
for the Clinical Study of the F1 Offspring of A-bomb Survivors
held at the Hiroshima Laboratory

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Conference and Workshop Reports
by Committee Vice Chairman Hiraku Takebe, thedraft revisions were approved. The meeting concluded with Chairman Shimao’s summary report,
followed by Dr. Shore’s closing address and wordsof gratitude to the participants.
A high participation rate for such incidence
studies is a requirement for improved quality andreliability in estimation of disease risk. We would
like to improve the participation rate in the clinicalexaminations by quickly putting into practice theproposals provided at the latest committee meeting.
We also will continue our efforts to emphasize toparticipants the health-related benefits from participation in the examinations and the significance ofthe longitudinal study by actively contacting thestudy participants by letter and/or telephone.

Members of the Scientific and Ethics Committee for the Clinical Study of the F1 Offspring of
A-bomb Survivors
Tadao Shimao (Chairman), Consultant, Japan
Anti-Tuberculosis Association
Hiraku Takebe (Vice Chairman), Fellow, Kinki
University Atomic Energy Research Institute
Hirotsugu Ueshima, Special Contract Professor,

Lifestyle-Related Disease Prevention Center,
Shiga University of Medical Science
Takashi Kawamoto, Professor, Graduate School of
Education, The University of Tokyo
Shinsuke Kimura, Attorney, Kimura Shinsuke Law
OfficeTakashi Gojobori, Vice Director and Professor,
National Institute of Genetics
Hideo Sasaki, Director, Health Management andPromotion Center, Hiroshima Atomic Bomb
Casualty Council
Steve Wing, Associate Professor, Department of
Epidemiology, School of Public Health, University of North Carolina
Kazuo Tajima, Director, Aichi Cancer Center Research Institute
Masao Tomonaga, Director, Japanese Red Cross
Nagasaki Atomic Bomb Hospital
Taisei Nomura, Professor Emeritus, Osaka University
Norihiko Hayakawa, Professor Emeritus, Hiroshima
University
Katsumi Furitsu, Visiting Lecturer, Hyogo Collegeof Medicine
Eiji Maruyama, Professor, Graduate School ofLaw, Kobe University

RERF International Workshop: Radiation Effects on Mutation
in Somatic and Germline Stem Cells
Asao Noda, Assistant Chief
Department of Genetics
The above workshop was held in the RERF
Auditorium on January 18–19, 2012
Stem cells play a principal role in the continuous provision of new cells in the body. As long asstem cells are healthy, old cells can be replaced by
new cells, whereby tissue homeostasis is maintained. Dramatic progress has been made recently
in the area of research into somatic and germline
stem cells, and consideration of radiation effects onsuch stem cells is important for investigation ofradiation effects on human health. The international workshop, aiming at debate about the current
status of stem cell research as well as effects ofradiation on stem cells, was attended by four stem
cell researchers from abroad and five from Japan(experts related to stem cells of the small intestine,skin, testis, and bone marrow).
At the workshop, lectures were provided by
Catherine Booth (keynote lecturer; Epistem Ltd.,UK), David T. Breault (Harvard Medical School,
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USA), Jolyon H. Hendry (Christie Hospital NHS
Foundation Trust, UK, and member of the International Commission on Radiological Protection[ICRP]), Toshio Suda (Keio University), Takashi
Shinohara (Kyoto University), Claudia E. Ruebe(Saarland University, Germany), Emi Nishimura(Tokyo Medical and Dental University), Hiroshi
Mitani (The University of Tokyo), Asao Noda
(Assistant Chief, RERF Department of Genetics),
Nori Nakamura (RERF Chief Scientist), andOhtsura Niwa (Professor Emeritus, Kyoto University). The workshop concluded with a comprehensive discussion regarding how data related to radiation effects on stem cells would contribute to
RERF’s ongoing research into cancer risk estimation.
The following questions were introduced at theworkshop and identified key problems for consideration by all participants:(1) Where do tissue stem cells reside and function
RERF Update Volume 23, Issue 1, 2012

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Conference and Workshop Reports

(2)
(3)
(4)
(5)

(6)
(7)

in tissues undergoing typical cell turnover? Is
it possible to locate stem cells within tissue,
by characterizing tissue stem cells?
What characteristics do stem cell niches maintaining tissue stem cells have?
What effects does radiation exposure have onstem cells, or, how do stem cells behave in
response to radiation exposure?
What effects does radiation response of stem
cells have on tissue radiosensitivity and recovery from radiation exposure?
Functional deterioration of stem cells is suggested as the cause of aging. Is it possible tosuccessfully observe such histological (pathological) changes? Does radiation exposure
affect the aging of tissues?
Is it possible to explain risks from fetal orchildhood radiation exposure in terms of the
behavior of tissue stem cells?
Is it possible to explain risks of radiation carcinogenesis in terms of the radiosensitivity oftissue stem cells?

The following summarizes my thoughts regarding the questions and issues listed above, after taking into account reports by workshop participants:
The small intestine is a target organ of radiation
effects. In the body, the small intestine is composedof the most active tissues in terms of cell division,
with digestive and absorptive cells newly born insmall-intestinal villi completing their roles inapproximately five days, upon which they are
replaced by new cells. The intestinal basal membrane contains intestinal crypt structures, which inturn house intestinal stem cells. Dr. Booth outlined
previous intestinal stem cell studies, and Dr.
Breault introduced the latest findings, concludingthat Tert (+) cells, which reside at the +4 crypt

position from the crypt base and undergo cell division extremely slowly, are true stem cells (multipotent intestinal stem cells: ISCs). Future tasks
include determination of whether or not it is possible to explain intestinal radiosensitivity and acuteradiation symptoms observed at the individual levelin terms of radiosensitivity of ISCs.
The most radiosensitive stem cells are those of
the bone marrow. Radiation therefore causes symptoms of anemia. Dr. Suda discussed a maintenancemechanism for bone marrow stem cell properties
and concluded that hypoxia in niches and hypoxic
signaling (HIF-1α signaling) are indispensable aspart of this mechanism for maintaining stem cellquiescence. Dr. Hendry stated that there was a correlation between degree of differentiation, hypoxia,
and radiosensitivity of bone marrow stem cells,
adding that the more undifferentiated/hypoxic cells
have greater radio-resistance. Discussions engaged
in by the four researchers mentioned above suggested the possibility that a hierarchical stem cellorganization governing ‘stemness’ is present andthat more primitive stem cells are more quiescent(slowly cycling) and more radio-resistant. This
would represent a new development transcending
the conventional wisdom that self-renewing stem
cells are highly sensitive to radiation.
Spermatogonia are the original germ cells, fromwhich spermatozoa are produced, and hence thepossibility exists that radiation effects on spermatogonia are expressed as hereditary, or transgenerational, effects. Dr. Shinohara has successfully cultivated spermatogonia extracted from mice testis,while maintaining stem-cell properties. If in vitro
reproduction of meiosis and spermatogenesis canbe realized in the future, the field of radiobiology
would benefit significantly. Dr. Ruebe, who investigated the recovery process (damage repair) in sper-

Participants of the international workshop
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RERF Update Volume 23, Issue 1, 2012

Conference and Workshop Reports
matogonia from radiation exposure, reported thatthe initial phase of spermatogonia radiation
response was different from that of somatic cells.
The skin is composed of tissue cells that repeatedly divide over a lifetime and contains stem cells.
The skin is one of the target organs of radiation
disorders and is suited for observation of the aging
process. Dr. Nishimura, who analyzed radiationaccelerated senescence mechanisms in melanocyte
stem cells, reported that these stem cells differentiated into pigment cells in stem cell niches, leading
to the aging of such cells. This suggests that, since
stem cell niches cannot maintain melanocyte stem
cells as stem cells, aging of the skin may very wellstart at this point.
With regard to the development of model systems for research into radiation effects on stem
cells, Drs. Mitani and Noda reported on medaka(Oryzias Latipes)- and mice-based experimental
systems, respectively. Both aimed at visualizing
effects on stem cells (apoptosis and mutations) invivo. Those systems are likely to make visible andobservable the origins of radiation carcinogenesis

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15
in the body.
Sometimes effects of adulthood radiation exposure persist over a lifetime, while in some cases
effects of fetal exposure are not detected postnatally. Dr. Nakamura reported that no effects of fetal
radiation exposure observed using chromosomal
aberrations as a marker were detected in adult lymphocytes.
Finally, Dr. Niwa reported on changes in tissue
stem cells and stem cell niches through ontogeny,
growth, and aging, adding that the relevant changes
affect risk of radiation carcinogenesis.
In relation to this workshop, I would like to takethis opportunity to express my deep appreciation
for the support we received from the Ministry of
Health, Labour and Welfare as well as the cooperation from so many people in line with the plan prepared by the RERF Department of Genetics. A
more detailed account of the workshop has been
published and is available at the International
Journal of Radiation Biology.
DOI: 10.3109/09553002.2012.683512

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Science Articles

Highlights of RERF Departments: Research
Activities in the Department of Genetics
Yoshiaki Kodama and Jun-ichi Asakawa
Department of Genetics, RERF
Summary
The Department of Genetics consists of twolaboratories, the Biochemical Genetics Laboratory
and the Cytogenetics Laboratory. The Biochemical
Genetics Laboratory has conducted research toinvestigate whether mutation rates have significantly increased among children born to A-bomb
survivors and has developed the necessary techniques for such research. Extensive research conducted thus far has not demonstrated evidence ofgenetic effects from A-bomb exposure.1,2 The laboratory has also collected blood samples from families containing at least one A-bomb survivor(mother-father-child) to secure DNA samples necessary for molecular biology research and is establishing Epstein-Barr virus (EBV)-transformed cellstrains (B cells). Since genome analysis became
possible in the late first decade of the 2000s, thelaboratory is now conducting research on radiationrelated germline mutations in both animal models
and humans, using high-density microarrays (1–2
million probes). Further, with recent rapid advancesin technology, whole-genome base sequencing has
become possible.
The Cytogenetics Laboratory has screened chromosome aberrations in somatic cells from A-bomb
survivors and focused on evaluation of biologicalresponses with the aim of carrying out biologicaldosimetry. The laboratory has also utilized electron
spin resonance (ESR) spectroscopy to identify
trace substances that were generated by radiation
exposure and have remained in tooth enamel. The
purpose of these studies is to obtain information toconfirm individual radiation dose estimates used
for evaluation of risk of cancer and noncancer diseases due to exposure to A-bomb radiation andimprove the quality of such estimates. The laboratory is also conducting in genetic research onbreast cancer and skin cancer as well as research
involving the detection of irreparable DNA damage. Furthermore, the laboratory developed a new
animal model system for estimation of genetic
effects of low-dose radiation and succeeded in creating mice with cells that generate green fluorescence upon mutation. Recent research activities
and the future plans of the Department of Genetics
are summarized below.
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Department Staff
The Department of Genetics has a chief, anassistant chief, two laboratory chiefs, a senior scientist, two research scientists, 13 technicians, andtwo administrative staff members.

Research Scientists of Genetics (first row from left) Mieko
Kodaira, Yoshiaki Kodama (Department Chief), Nori
Nakamura (Chief Scientist), Asao Noda, (second row fromleft) Yuko Hirai, Jun-ichi Asakawa, Yasunari Satoh, Kanya
Hamasaki

Biochemical Genetics Laboratory
Introduction of high-density microarray
technique
Since genomic base sequencing has been completed for the human and mouse genome, laboratories can now conduct genetic research at the wholegenome level using high-density microarrays. In
2009, a high-density microarray system was introduced into the Biochemical Genetics Laboratory at
RERF. With the comparative genomic hybridization (CGH) technique using the microarray system,
copy number variations (CNVs; gene amplifications or gene deletions) in two DNA samples for asingle species can be examined. Since mutations
induced by radiation are considered to be mainly
gene deletions resulting from DNA double-strand
breaks, CGH research using high-density microarrays is now considered to be an appropriate technique for studying radiation-induced genetic
effects.
As a result of improvements in CGH experiRERF Update Volume 23, Issue 1, 2012

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Science Articles
Accurate detection of large deletions/amplifications
Chromosomal location (bp)log23/2 = 0.58
one copy gain

log2 ratio~300 kb

one copy loss
log21/2 = -1

~22 kbFigure 1. Copy number variations at 22 kb and 300 kb on the mouse genome detected by the microarray CGH method.
Each of the points in the figure indicates the relative ratio of the copy numbers of the two DNA samples. Whenthe copy number is the same, log2 equals “0.” However, when the copy number in one DNA sample changes,
the absolute value of log2 changes by at least 0.4.

mental and analytical techniques, it has become
possible to detect from small to large CNVs (asillustrated in Figure 1), enabling the conduct of thefollowing three studies using high-density microarrays: (1) study of offspring of exposed male miceas a model for human male exposure, (2) study ofoffspring of exposed female rats as a model forhuman female exposure, and (3) study of children
born to A-bomb survivors in Hiroshima andNagasaki.
(1) Study of offspring of exposed male mice as amodel for human male exposureThis is a joint study carried out with Dr. Yoshiya
Shimada’s group at the National Institute of Radiological Sciences. His group was responsible for the
study’s gamma-irradiation, animal breeding, andextraction of F1 DNA samples. Male C57BL/6 (B6)
mice were exposed to 4 Gy of gamma rays andmated with female C3H mice eight weeks later (F1of exposed group). As the controls, F1 mice born tonon-exposed male B6 mice and female C3H mice
were used. CGH experimentation was conducted
for a set of DNA samples from one F1 mouse in the
exposed group and one in the non-exposed group.
As a result of CGH analysis conducted on 80 suchsets, 26 candidate CNV mutations were detected.
Analysis of the DNA of the parents of the F1 micein which these CNVs were detected showed thatfive of the CNVs were also detected in the parents.
Thus, these CNVs in the F1 were inherited fromtheir parents. The remaining 21 CNVs were denovo mutations (Figure 2). Of these 21 mutations
in total, nine were detected in the exposed group(six gene deletions found in six F1 mice, three gene
amplifications in three F1 mice), and 12 in the control group (seven gene deletions found in seven F1
mice, five gene amplifications in three F1 mice,
three gene amplifications in one F1 mouse). Judging only from the number of mutations, no genetic

Examples of idenfied CNVs : the size varied from small (2 kb) to large (2,600 kb)

12 probes: 12 kb

72 probes: 119 kb

2,123 probes: 2,600 kb

Figure 2. Examples of identified CNVs. The two right cases were de novo mutations observed in F1 mice only. The leftcase was a hereditary mutation because the same CNV was observed in the male parent.
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RERF Update Volume 23, Issue 1, 2012

Science Articles
effects of radiation were suggested. Analysis is
now under way for clarifying the mechanism of
production of the abovementioned mutations andtheir characteristics at the molecular level.
(2) Study of offspring of exposed female rats as amodel for human female exposure

In comparison with the male animal model, thefemale animal model was problematic. This wasdue to the fact that female mice become sterile (dueto depleted ova) after radiation exposure as a resultof extensive death of immature oocytes (target cells
at risk), because such cells in mice are extremely
sensitive to the killing effects of radiation,3 andtherefore an F1 generation is not possible. Afterinvestigation of several non-mouse animal species,
we identified the rat as a good model. We conducted large-scale mutation screening with DNA
2-dimentional electrophoresis (DE) technique of
750 F1 rats derived from irradiated immature
oocytes (2.5 Gy of gamma rays) and of 750 F1 rats
from unirradiated females as a control group. We
selected about 1,500 spots each derived fromfemale parents and male parents deemed to beappropriate for detection of mutations, andsearched for mutation candidate spots showing
qualitative changes (gene copy number changes)
and positional changes. As a result of analysis of
1,500 images each from the exposed group and thecontrol group, totaling 3,000 images (equivalent toa total of 2.3 million gene locus tests), it was suggested that genetic effects of radiation in female
exposures are smaller than those in spermatogenous cells of male mice. In a new research protocol
using high-density microarrays, with F1 rats fromthe exposed group and control group comprising aset, screening of CNV mutations using the CGH
technique is being conducted for 200 sets of DNA
samples from 200 rats from the 2.5 Gy exposuregroup and 200 rats from the control group, all ofwhich were used in the DNA 2-DE study. As of
April 2012, CGH experimentation has been completed for about 160 sets of the rats. Experimentation will be completed soon for all the sets.
(3) Study of children born to A-bomb survivors in
Hiroshima and Nagasaki

Genetic effects of A-bomb radiation (trans-generational effects) still have not been fully elucidated due to the low rates of spontaneous and radiation-induced mutations in germ cells. Therefore,
we are conducting CGH research based on highdensity microarray technology for a total of 688
persons, i.e., both parents of 184 families with oneof the parents exposed to high doses of A-bombradiation and their 320 children (160 from paternally exposed families and 160 from maternally
exposed families). We plan to use a 3 × 1.4 M highReturn to Table of Contents

18
density microarray that contains three identical setsof 1.4 million probes (mean interval: 2.2 kb) on asingle slide. The microarray permits us to analyze
DNA samples from three subjects at a time on asingle array. We do not expect to discover a sufficient number of mutations in the 160 children of
the maternally exposed families to detect an elevated rate, because the mutation rate obtained in
irradiated rat immature oocytes appeared to beconsiderably lower than that in rat spermatogonia.
Nonetheless, analysis of this group is indispensable
because the paternal alleles were not exposed toradiation and hence serve as controls for the abovementioned paternally exposed families. The analyses will provide far more information than is currently available on risks associated with maternaland paternal radiation exposure.
In the model experimentation using mice or rats,
the genomes of such animals used are almost thesame and CNVs are extremely rare. However, inthe human genome there are more than several
hundred different CNVs.4 In the CNV mutation
search using the CGH technique, CNVs with highfrequency (polymorphic CNVs: same mutations
observed in at least two persons out of 50) are usually considered to be hereditary. Therefore, even if
such CNVs are detected in children, they are notconsidered to be candidate mutations. First, tocomprehensively search for CNVs in study subjects, CGH experimentation was conducted in 50
father-mother-child trios using specific persons as
controls. DNA from a Caucasian male used worldwide as a control and DNA from the first Japanese,a male, to undergo whole-genome sequencing werestudied. To enhance quality, CGH experimentation
was performed using the dye-swap method, inwhich replacement of fluorescent dyes is conducted for marking two samples in a single trio set
with the relevant experiments conducted twice. To
date (as of December 2011), CGH experimentation
has been completed for 26 trios. As a result of comparison of CNVs among 15 trios, a total of 10,639
CNVs were detected in 30 fathers and mothers andclassified into 3,070 different types of CNVs.
Slightly more than 50% of these CNVs were as
small as around 3 kb, including only two probe
regions. As shown in Figure 3, there are about 300
different CNVs in each individual when theJapanese male was used as reference. However,when the Caucasian male was used, additionalroughly 200 unique interracial CNVs were identified (Figure 3, the red areas of the bar graph).
Based on the above results, we decided to use thesaid DNA for the subsequent experiments, since
the Japanese DNA, being of the same ethnic groupas that of the subjects, was considered to be appropriate for use as reference for mutation searches.
Using the abovementioned Japanese DNA as a
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Number of individual CNV among 30 Japanese (parents from 15 families)
Idenfied only with Caucasian reference DNA

Number of CNV

Idenfied with Japanese reference DNA

Individual ID
Reference:
Caucasian DNA

Reference:
Japanese DNA• The use of a Japanese DNA as the reference was a good choice in our CGH study.
Figure 3. CNVs identified in 30 Japanese. The term “p1F” indicates the paternal DNA of pair 1 and “p1M” thematernal DNA of pair 1. At least half of about 300 CNVs in any individual are only about several kb. As
the size of such CNVs increases, CNV numbers decrease.

control, analysis of 50 trios in Hiroshima andNagasaki will be conducted to identify polymorphic CNVs. If CNVs different from those CNVs
are detected only in the children of the trios, weplan to analyze such rare CNVs as candidate denovo mutations. By so doing, it is expected to bepossible within a few years to understand at thewhole genome level the problems of genetic effects
that are as yet unresolved.
Current status and problems of whole-genome
base sequencing
Genome analysis, especially base sequencing,
continues to make remarkable progress withadvances in IT technology. There are now privatecompanies and research organizations that provide
whole genome sequencing (WGS) services, making whole genome information available at relatively low cost. However, since the genome of
mammals, including humans, consists of a large
number of bases (2–3 × 109), 30,000 erroneousbase sequences may be obtained even with analysis
that is 99.999% accurate. In reality, about 30 spontaneous point mutations actually occur in thehuman genome. It would be next to impossible todifferentiate these actual mutations from the said
30,000 false-positive base sequences. In addition,
software used for analysis of such large amounts of
information is not appropriate for identifying genedeletions (especially heterozygotes) mainly
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induced by radiation. Furthermore, individual differences in human genome sequences is a major
factor that complicates the analysis. In fact, we
performed (commercially available) WGS using
cultured cells derived from a Japanese male anddetected about 3.2 million single nucleotide polymorphisms (SNPs), 100,000 deletions/insertions of
1 bp, 70,000 deletions/insertions of from 2 bp to 30
bp, and 5,000 genomic structural abnormalities/
copy number variations, in comparison with humanreference sequences. For the above reasons, it is at
this time not practical to use WGS for evaluation ofgenetic effects in A-bomb survivors’ children.
To establish a system for accurately and efficiently identifying radiation-induced mutations by
WGS, the Biochemical Genetics Laboratory isplanning to conduct analysis of radiation-induced
mutations using WGS and cultured cells from anindividual with the same genetic background andanimal models previously used. In particular, we
obtained a Grant-in-Aid for Scientific Research for
a WGS-dependent study of radiation’s genetic
effects using rats in a female exposure model andare making preparations for conduct of the study.
Analysis of WGS data will be carried out under theguidance of Dr. Tatsuhiko Tsunoda’s group at
RIKEN, the organization that performed wholegenome analysis in a Japanese participant for the
first time.

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Frequency of cells with stable
chromosome aberrations

Cytogenetics Laboratory
Cytogenetics study of A-bomb survivors
Since chromosome aberrations show high specificity for radiation, it is well known that frequencyof chromosome aberrations can be used as an indicator of level of radiation exposure. The purposesof the chromosome study for A-bomb survivors areto conduct biological dose estimations using chromosome aberrations as markers, to investigate biosamples from each survivor, and to evaluate physical dose estimates arrived at by computation.
The chromosome study for the Adult HealthStudy (AHS) population was initiated in the late1960s. Because more than 20 years since thebombings had already passed at that time, most
unstable chromosome aberrations, including theeasily identifiable dicentric chromosomes andrings, had nearly completely disappeared from theperipheral blood of A-bomb survivors. In this chromosome study, therefore, only stable chromosome
aberrations (translocations or inversions) werestudied. Giemsa staining was used from the time ofinitiation of the study through 1993. Using thisGiemsa staining method, about 2,000 cases in
Hiroshima and about 1,000 cases in Nagasaki werestudied. The study showed a wide scattering of frequency of chromosome aberrations compared withthe actual physical radiation doses calculated forboth cities, and a difference in the dose-response
relationship between Hiroshima and Nagasaki. At
doses of 1.5 Sv or less, the response was significantly larger in Hiroshima than in Nagasaki (Figure4).5 Since research using Giemsa staining was
independently conducted at the laboratories in

Hiroshima and Nagasaki, the possibility of detection errors dependent on the laboratory (observer)
could not be negated. This is an especially important point in considering differences between
Hiroshima and Nagasaki.
In the late 1980s, a new chromosome analysis
technique called fluorescence in situ hybridization(FISH) was developed. With this technique, specifically targeted chromosomes can be stained using
DNA probes specific to selected chromosomes.
This technique enables accurate and speedy detection of exchange-type abnormalities, includingtranslocations. We started to use the FISH technique in 1994 in a chromosome study of A-bomb
survivors. At the same time, to resolve the possibility of detection errors between the two laboratories,
all work related to the chromosome testing was
conducted exclusively at the laboratory in
Hiroshima. To date, analysis was completed forabout 900 cases in Hiroshima and about 500 casesin Nagasaki. Like in the study using the Giemsa
method, the study using FISH revealed a wide scattering of chromosome aberration frequencies compared with physical doses. Differences in the doseresponse relationship, presumably due to shielding
status, were also observed. The above findings
suggest that there are errors in the dose estimatesfor some A-bomb survivors. On the other hand, thedifferences between Hiroshima and Nagasaki wereremarkably reduced using FISH, suggesting thatthe city differences previously observed were due
to differences in abnormality detection rates
between the two laboratories (observers).

Hiroshima㻜㻚㻤Nagasaki

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㻜㻚㻢

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㻜㻚㻠

㻜㻚㻞

㻜㻚㻞

㻜㻚㻜

㻜㻚㻜
㻜

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㻞

㻟

㻠

㻜

㻝

㻞

㻟

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Bone marrow dose 䠄䠯䡒䠅
Figure 4. Physical dose estimates and chromosome aberration frequencies. Each point indicates data of individual A-bomb survivors (1,980 cases in Hiroshima and 1,062 cases in Nagasaki). The solid line shows
dose-response relationship and the dashed lines represent 95% confidence interval. The dotted lines
are an assumed coefficient of variation of 50% of the estimated doses beyond the confidence interval.5

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Lack of cytogenetic dose response in the in utero
population
Based on epidemiological research conducted inEngland in the 1950s concerning the developmentof cancer among children, it had been consideredthat the fetus is highly sensitive to radiation. However, in the chromosome study of those exposed inutero to A-bomb radiation, almost no dose response
was observed with respect to frequency of translocations in the peripheral lymphocytes of such subjects. On the other hand, clear dose-response relationships were observed regarding translocation
frequencies in the lymphocytes of the mothers of
those exposed in utero (Figure 5a).6 This finding
was reproduced in a study of hematological cells in
irradiation experiments later conducted using mice
(Figure 5b).7 To study whether this finding was
unique to hematopoietic cells, rat fetuses were
exposed to radiation, and frequency of chromosome aberrations in mammary epithelial cells was
examined. Examinations conducted 6–45 weeks
after irradiation showed that in the exposed fetuses,
like in the mothers, radiation damage remained(manuscript in preparation). Therefore, such results
suggest that the lack of a translocation dose
response after exposure in utero was tissue-dependent. At present, to confirm the results of this study,
which used mammary cells, a similar study using
mouse thyroid epithelial cells is currently underway.

Estimation of exposure dose using tooth enamel
By measuring the amount of CO2– radicals
remaining in tooth enamel, radiation exposure
doses for individuals can be estimated. For such an
estimation, enamel is separated from a tooth
extracted for therapeutic reasons, and the amountof CO2– radicals is measured using ESR spectroscopy. Since ESR signal intensity is proportional to
the radiation dose received and does not changeover time, exposure dose can be measured directly,
irrespective of the mode of exposure. This technique has been used in dose assessment for those
exposed to radiation in the Chernobyl accident andother exposures. Recently, a method was also
developed for use in making direct measurementsof teeth in the mouth, not extracted teeth. The purposes of the study are to estimate using the ESR
method, individual doses using tooth enamel and tocompare the results with DS02 doses and the frequency of chromosome aberrations in lymphocytes
from the same individuals. ESR signal intensity isconverted to gamma rays using the calibration
curve from cobalt gamma-ray irradiation.
One of the problems with ESR measurement
was how to treat exposure to diagnostic dental X
rays. However, because a long time had passed
since the atomic bombings, obtaining all diagnostic
records was considered a difficult task. Furthermore, it was thought that medical exposure doses
may be different by production year and model ofa) Chromosome study of those exposed in uterob) Mouse irradiation experiment
40

20Translocation frequency

Translocation frequency

25

15
10
5
0
0

0.5

1

Radiation dose (Gy)

1.5

20

0
0

1

2

Radiation dose (Gy)Figure 5. In utero exposure and chromosome aberrationsa) Results of the chromosome study of those exposed in utero. No dose-response
relationship was observed regarding frequencies of translocations in blood lymphocytes among those exposed in utero (●) (age at examination: 40 years). However,dose response was observed in the mothers ( ) of those exposed in utero.6 The
curve shows the frequency of dicentric chromosomes resulting from in vitro irradiation (dicentric chromosomes and translocations are thought to occur at the same
frequency).
b) Results of irradiation experimentation using mice. Mice which were pregnant for15.5 days were exposed to radiation. Lymphocytes of the offspring were examinedon the 20th day after birth. Symbols indicate the mice exposed in utero (●) and theirmothers (■). Results similar to those from the chromosome study of humans exposed
in utero were obtained.7
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wisdom teeth. As for this subject, the tooth forwhich the measurement was made had not fully
developed at the time of A-bomb exposure. For
confirmation, we requested this person to donate
another tooth other than a wisdom tooth, but wehave not yet obtained the said donation. Thus,
although dose estimation using tooth enamel is aneffective method, difficulties in collecting samples(teeth) is a major problem.

diagnostic equipment, and therefore accurate evaluation of diagnostic dental X rays was expected tobe difficult. Therefore, we measured each of theteeth obtained by dividing it into an outer part (buccal side) and an inner part (lingual side). Since
X-ray diagnosis at dental clinics mainly involves
radiation exposure on the outer sides, we thought
there may be differences between the outer andinner teeth. When we actually conducted measurements, however, we found little difference between
the outside and the inside of the back teeth, while
the signal from the enamel of the outside of thefront teeth was rather large.8 The large signal commonly found in the outside of front teeth may be
due to ultraviolet ray effects, but no clear reasons
have yet been found. Since this problem became
apparent, the back teeth (large molars) are now
used in our ESR measurements.
In Figure 6, for 61 A-bomb survivors, frequencyof translocations in lymphocytes (Y axis) was compared with physical dose (left panel, X axis) and
ESR dose estimates obtained from the large molars(right panel, X axis).8 In the left panel, a wide scattering can be seen in the relationship between thephysical dose and the frequency of translocations,while in the right panel, the distribution of plots issmaller, indicating good correlation between thedose information obtained from teeth and the frequency of translocations. The one exception in theright panel is the “wisdom tooth” (indicated by anarrow). The subject was 15 years old at the time of
the A-bomb exposure, and the estimated dose fromanalysis of the tooth was 0 Gy. However, the frequency of translocations in this subject is morethan 20%, suggesting exposure to a high level ofradiation. It was only later that this tooth was foundto be a wisdom tooth. It is known that there is large
individual variation in the timing of formation of

Dose estimation for distally exposed persons
using tooth enamel
As for the radiation dose (gamma rays and neutrons) directly released from the atomic bombs,
consensus was reached among the physicists concerned (DS02 dose estimates). However, exposure
to so-called residual radiation, including exposure
to secondary radiation due to activation of the soil
by neutrons or nuclear fission products containedin radioactive fallout, is a controversial topic
because of insufficient measurement data. To provide new information for discussion of this issue,
we conducted an evaluation of exposure doses
using ESR for teeth donated from A-bomb survivors in Hiroshima who were exposed to the bombat distances of 3 km or greater from the hypocenter
and whose DS02 dose estimates were less than 5
mGy. We evaluated 49 persons who were exposedto the bomb at the ages of 10 years or older using a
total of 56 donated molars. To examine the effects
of diagnostic dental X rays, these teeth were cut
into outer and inner parts, and an ESR measurement was conducted separately for each part. Doseestimates of the 56 large molars ranged from –200
mGy to 500 mGy (gamma rays). The mean dose of
the outer side of the teeth was 70 ± 157 mGy(median value: 17 mGy), and that of the inner side
34 ± 127 mGy (median value: 13 mGy) (Figure 7).

40
30
20
10
0

0

1

2

3

Physical dose estimate (Gy)4Frequency of translocations

Frequency of translocations

50

50
40
30

Wisdom tooth

20
10
0
0

1

2

3

4

ESR dose estimate (Gy)Figure 6. Results of a comparison of the frequencies of translocations in lymphocytes with physical dose estimates (left panel) and ESR dose estimates (right panel) for 61 A-bomb survivors. The curve in theright panel shows a dose response for dicentric chromosomes from an in vitro irradiation experiment.
The arrow indicates a “wisdom tooth” from a person exposed to A-bomb radiation at the age of 15.8
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RERF Update Volume 23, Issue 1, 2012

23

Dose estimates of tooth enamelon the lingual side (mGy)㻌

Science Articles

㻢㻜㻜

㻠㻜㻜

㻞㻜㻜
Median value = 13 mGy

㻜

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㻞㻜㻜㻜

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Distance from the hypocenter (m)Figure 7. Dose estimates obtained from tooth enamel ESR
and distance from the hypocenter for distally exposed individuals in Hiroshima9

Four of the 49 persons were exposed to A-bombradiation in the “black rain” area, but did notexhibit extremely high dose information. In threedonors, exposure doses of both the outer and theinner parts of the teeth were as high as 300–400
mGy. These donors may have been exposed tosome type of radiation, but the exact reason forthese high doses is unknown. Nevertheless, theexposure dose estimated by ESR for the 49 distally
exposed individuals did not indicate evidence for
exposure to high levels of radiation (for example,
more than 1 Gy) from residual radiation, as suggested by some parties.9
Genetics study concerning breast cancer
Epidemiological research at RERF has shownthat breast cancer among A-bomb survivors has ahigh mean excess relative risk (ERR), strongly suggesting association of the disease with radiation
exposure. Moreover, it is assumed that the ERR ofearly-onset breast cancer cases (age at the time ofbombing: less than 20 years old, age at diagnosis:
less than 35 years old) is especially high. We
hypothesized that the risk of early-onset breast
cancer risk is high in A-bomb survivors because
normal gene functions were lost due to radiation
exposure in those inheriting breast cancer-related
gene variants (heterozygotes). To investigate thispossibility, we examined specific SNPs considered
to be associated with early development of breast
cancer. The study indicated that specific genotypes
exist in large numbers in the early-onset breastcancer group among A-bomb survivors (exposedgroup, age at diagnosis: less than 45 years old).
This study is ongoing.
Genetics study concerning skin cancer
The frequency of patients (homozygote) with
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cancer-prone recessive hereditary disorders, suchas xeroderma pigmentosum (XP), is usually low, atseveral cases per 100,000 people, but carriers (heterozygote) are not rare, with a frequency on theorder of one percent. However, there is little data
regarding cancer risk in such heterozygote carriers,
as they are generally difficult to identify. But, theexamination of carriers of an inactive mutant allele
is most appropriate as a model in establishing cancer risk in carriers, on the assumption that the specific gene function decreases about 50%. The aimof this research is to evaluate the cancer risk insuch carriers by comparing the frequency of carriers bearing a founder mutation in the XPA gene in
non-melanoma skin cancer patients against a control population, by taking advantage of the fact thata founder mutation at the XPA gene (inactive mutation) exists at a relatively high frequency in theJapanese population and can be found easily using
the polymerase chain reaction-restriction fragment
length polymorphisms (PCR-RFLP) method. In
this research, we plan to conduct screening of
1,000 non-melanoma skin cancer cases and compare the frequency with that in a control populationof 1,500 individuals. This research is suitable for amodel in establishing cancer risk in heterozygous
carriers of gene mutations related to cancer-prone
recessive hereditary disorders.
Detection of irreparable DNA damage
It is known that some DNA double strand breaks(DSBs) induced by radiation cannot be completely
repaired and exist for a long period of time. It isconsidered that such irreparable genome damage isinvolved in cell death and functional changes in tissues. However, since it is impossible to biochemically differentiate such irreparable damage from
repairable damage, the frequency and biologicaleffect of such irreparable damage cannot be precisely assessed. We consider repair foci that areformed after radiation exposure and persist within
the nucleus for a long period of time or permanently to be irreparably damaged sites, and are
conducting their characterization and review of
their biological effects. Eventually, we want toquantify irreparable DSBs within cells and tissues
exposed to radiation in the past.
Development of animal model system for evaluation of genetic effects of radiation
To study genetic (transgenerational) effects ofradiation, we are creating model mice in which
germ-cell mutations can be detected easily, insteadof using F1 individuals born to irradiated parents.
Multiple detection systems are being examined.
One of the systems is based on the idea that cells
generate fluorescence upon reversion.10 Anothersystem allows cells to generate fluorescence by forRERF Update Volume 23, Issue 1, 2012

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HPRTdupGFP mice

Radiation

X chromosome
HPRT(-)GFP(-)

Reversion

HPRT(+)GFP(+)

Figure 8. Cells become GFP(+) by reversion from partial duplication of endogenous gene.

ward mutation in the body.11 Thus far, the former
system has reached the stage of feasibility. Usingmouse embryonic stem (ES) cells as host cells, apartial duplication region was introduced into the
HPRT gene and connected with the green fluorescent protein (GFP) gene (Figure 8). Because ofrecombination arising in the duplication region, it
was confirmed that the reversion cells became GFP
positive (Figure 9). Therefore, knock-in mice were
produced using these ES cells (injection of ES cells
into fertilized eggs and transplantation of thosecells into the fallopian tubes of pseudopregnant
mice were outsourced). Although the promoter
activity of the endogenous HPRT gene was sufficient in ES cells, it was not strong enough at thecellular level of a mouse, and GFP-positive somatic
cells were not discovered. Therefore, we replaced
the HPRT gene promoter of the ES cells with a
CAG promoter, and again produced mice. In themice thus created, GFP-positive cells were identified at the cellular level in many systems, including
the pancreas, small intestine, liver, and testis. In
other words, we created mice in which mutations incells throughout the body can be measured in situ.
In these mice, only recombinant mutations in thetandem duplication region can be identified. However, cells with mutation in somatic cells and germ
cells in such mice can be very easily detected as

Figure 9. HPRT(+) GFP(+) ES cell colonies obtained fromspontaneous mutation.
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cells generating green fluorescence. Furthermore,mutation frequencies in hematological cells can beobtained by flow cytometer. At present, with consideration given to the method of measurement ofmutation frequencies, measurements of mutation
rates in the cells of various organs are being conducted.
Information on the genetic risks from radiationin humans largely depends on the results frommutation studies using the mouse specific-locus
method. However, as those studies required as
many as several million F1 animals, information on
low-dose radiation is limited. Use of the abovementioned model mice may make it possible toevaluate genetic effects from low-dose radiation
relatively easily without using a large number of F1
animals. Furthermore, if the frequency of somatic
mutations in an animal can be determined in vivo,
new information could be provided for cancer risk
evaluation for low-dose radiation, which to thispoint has been difficult. In addition, it would bepossible to determine the frequency of mutations inthe somatic cells of an F1 mouse born to irradiatedmice and examine whether genetic instability canbe observed.

Future Studies
Major activities to be conducted in the future by
the Department of Genetics are as follows:
1) Evaluation of genetic effects of radiation on
A-bomb survivors’ children
Biosamples (blood cells) from about 1,000
families (father-mother-child) are stored in liquid nitrogen. These biosamples will be analyzed by the latest techniques, including highdensity microarray technique, multicolor FISH
technique, and whole-genome base sequencing
using a next-generation sequencer, for evaluation of genetic effects of A-bomb radiation.
2) Evaluation of effects of radiation exposureusing an animal model system
Using genetically modified mice in whichcells generate green fluorescence by mutation(GFP mice), efforts to detect and quantify radiation-induced mutations in vivo will be carriedout, and evaluation of genetic effects by radiaRERF Update Volume 23, Issue 1, 2012

Science Articles
tion exposure, elucidation of the mechanism ofcancer development, and research on genetic
instability will be performed.
3) Evaluation of exposure dose using biological25
dose estimates as indicators
A-bomb survivors’ exposure doses will bereassessed using chromosome aberration data
and ESR data from tooth enamel.

References
1. Kodaira M, Izumi S, Takahashi N, Nakamura N. No evidence of radiation effect on mutation rates at
hypervariable minisatellite loci in the germ cells of atomic bomb survivors. Radiat Res 2004; 162:350-6.
2. Kodaira M, Ryo H, Kamada N, Furukawa K, Takahashi N, Nakajima H, Nomura T, Nakamura N. No evidence
of increased mutation rates at microsatellite loci in offspring of A-bomb survivors. Radiat Res 2010; 173:20513.
3. Straume T, Dobson RL, Kwan TC. Neutron RBEs and the radiosensitive target for mouse immature oocyte
killing. Radiat Res 1987; 111:47-57.
4. Conrad DF, Pinto D, Redon R, et al. Origins and functional impact of copy number variation in the humangenome. Nature 2010; 464:704-12.
5. Kodama Y, Pawel DJ, Nakamura N, et al. Stable chromosome aberrations in atomic bomb survivors: Resultsfrom 25 years of investigation. Radiat Res 2001; 156:337-46.
6. Ohtaki K, Kodama Y, Nakano M, et al. Human fetuses do not register chromosome damage inflicted byradiation exposure in lymphoid precursor cells except for a small but significant effect at low doses. Radiat
Res 2004; 161:373-9.
7. Nakano N, Kodama Y, Ohtaki K, et al. Chromosome aberrations do not persist in the lymphocytes or bonemarrow cells of mice irradiated in utero or soon after birth. Radiat Res 2007; 167:693-702.
8. Nakamura N, Miyazawa C, Akiyama M, et al. A close correlation between electron spin resonance (ESR)
dosimetry from tooth enamel and cytogenetic dosimetry from lymphocytes of Hiroshima atomic-bomb
survivors. Int J Radiat Biol 1998; 73:619-27.
9. Hirai Y, Kodama Y, Cullings HM, Miyazawa C, Nakamura N. Electron spin resonance analysis of tooth
enamel does not indicate exposures to large radiation doses in a large proportion of distally-exposed A-bomb
survivors. J Radiat Res 2011; 52:600-8.
10. Noda A, Kodama Y, Cullings HM, Nakamura N. Radiation-induced genomic instability in tandem repeat
sequences is not predictive of unique sequence instability. Radiat Res 2007; 167:526-34.
11. Noda A, Hirai Y, Kodama Y, Kretzschmar WW, Hamasaki K, Kusunoki Y, Mitani H, Cullings HM, Nakamura
N. Easy detection of GFP-positive mutants following forward mutations at specific gene locus in cultured
human cells. Mutat Res 2011; 721:101-7.

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RERF Update Volume 23, Issue 1, 2012

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Highlights of RERF Departments: Research
Activities in the Department of Radiobiology/Molecular Epidemiology
Yoichiro Kusunoki
Department of Radiobiology/Molecular Epidemiology, RERF
Abstract
To address the question of how atomic-bomb(A-bomb) radiation affects human health andcauses diseases, the Department of Radiobiology/
Molecular Epidemiology (RME) takes two
approaches—immunological and molecular oncological. The goal is to clarify the mechanisms linking radiation exposure and the development of various diseases, including cancer among A-bomb
survivors, as well as genetic susceptibility to diseases. Mechanistic understanding is needed as afoundation for more robust risk assessments ofradiation-associated diseases along with improved
prevention and treatment of these diseases.
Immunology studies investigate immunobiological alterations caused by radiation and aging, in
relation to disease development among A-bomb
survivors. Accumulating evidence suggests thatpast radiation exposure accelerates immunosenescence. To elucidate mechanisms of radiationrelated immunosenescence, we focus on radiation
and age effects on hematopoietic stem cells(HSCs), dendritic cells (DCs), and thymic structureand function. Along those lines, we evaluate radiation- and aging-related alterations in human HSC
and DC phenotypes and functions using assay systems established in collaboration with experts outside RERF. Studies on influenza vaccine responseand development of an immunological scoring system were also initiated to seek possible links ofradiation-related immunosenescence and diseasedevelopment. In addition, we are investigating
immunogenetic susceptibility to radiation-associated diseases. To date, polymorphisms of the following genes were found to underlie individuallydiffering and radiation dose-dependent risks of
diseases among A-bomb survivors: EGFR (lung),
IL18 (colon), IL10 (stomach), NKG2D (HCVrelated hepatitis and hepatocellular carcinoma),and HLA- DQA1 and DRB1 (diabetes mellitus).
Oncology studies aim to clarify mechanistic
relationships between radiation exposure anddevelopment of selected cancers among A-bomb
survivors. A papillary thyroid cancer (PTC) study
among the Life Span Study (LSS) cohort revealed
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that RET/PTC and anaplastic lymphoma kinase(ALK) rearrangements, rather than BRAF point
mutations, were early events in PTC that wereclosely associated with radiation. We thus areinvestigating the mechanisms of radiation-induced
thyroid carcinogenesis and are focusing on themolecular pathways involving rearranged RET and
ALK genes. Results of a colorectal cancer study
suggest that increased radiation dose is associatedwith microsatellite-unstable colorectal cancers carrying various epigenetic and genetic alterations.
Analyses of epigenetic alterations in peripheral
blood were initiated to assess age and radiation
effects, and a preliminary result suggests that aging
effects on methylation status may differ between
blood cell populations.

Department Staff
The RME Department is currently comprised ofa chief, an assistant chief (concurrently, a laboratory chief), a laboratory chief, eight research scientists, twelve technicians, and two administrative
assistants.

Research Scientists of Radiobiology/Molecular Epidemiology (first row from left) Seishi Kyoizumi (NIAID Project
Research Scientist), Tomonori Hayashi, Yoichiro Kusunoki(Department Chief), Kei Nakachi (RERF Consultant), Evan
B. Douple (Associate Chief of Research), Kiyohiro Hamatani,(second row from left) Kengo Yoshida, Reiko Ito, Norio
Takahashi, Junko Kajimura, Kazue Imai, Yasuharu Niwa,
Masataka Taga

RERF Update Volume 23, Issue 1, 2012

Science Articles

Research Projects and Recent Progress
1. Immunology Studies

Effects of A-bomb radiation on the immune system are being investigated using two approaches,i.e., immunobiology studies and immunogenome
studies, which primarily examine immunologicalphenotypes and genotypes of A-bomb survivors,
respectively. The studies are assessing immunobiological responses and genomic variations related todisease development in the Adult Health Study(AHS). The study outcomes are expected to contribute, not only to mechanistic understandings, butalso to risk estimation of radiation-related diseases
among the AHS subjects.
Immunobiology studies
Immunological changes we have previously
observed in associations with radiation exposure
among the AHS population were summarized in an
earlier issue of RERF Update (2010, issue 1).1
Most immunological phenotypes, including peripheral blood lymphocyte counts and functions, werealtered by radiation in a manner substantially similar to immune changes associated with aging (Figure 1). Research currently underway aims to understand the mechanisms of radiation-induced
alterations in the immune system and to determine
the associations of immunological changes withdiseases among A-bomb survivors.

Figure 1. Immune system changes with aging and radiation

Radiation-induced immunosenescence
Based on accumulating evidence for immunosenescence phenotypes among the AHS population,
we have hypothesized that A-bomb radiation has
accelerated immunological aging. To accumulate a
wealth of fundamental biological information on
the impact of radiation on aging of the immune
system, and to provide evidence of the impact ofradiation on immune aging and related healtheffects, we initiated a five-year collaborative study
with four Japanese and five U.S. institutions undera research contract with the National Institute ofAllergy and Infectious Diseases (NIAID).1 The
research program consists of five focused projects
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27
with explicit goals of assessing mechanisms andeffects of radiation on immune aging and dysfunction: 1) the role of HSCs and their microenvironment in T-cell development; 2) the role of DCs in
T-cell responsiveness and function; 3) immune
responsiveness to influenza vaccination; 4) a multivariable assessment of immune patterns to create
an integrated scoring system of immunity; and 5)
effects of A-bomb radiation on thymus architectureand function. Those study projects rely on the useof biosamples from AHS and LSS subjects and are
all conducted in close collaborations with the
Departments of Clinical Studies, Epidemiology,
Statistics, and Information Technology at RERF.
Project 1: Effects of ionizing radiation exposureand aging on HSCs
This study will examine the effects of radiation
exposure and aging on HSC including the determination of numerical and functional changes in thecirculating HSC pool in relation to age and radiation dose. We hypothesize that radiation exposure
induces premature aging of HSCs, resulting in
reduced numbers and impaired self-renewal ability,that in turn accelerates the loss of lymphoid potential. The working hypotheses in the studies on AHS
participants are therefore that there are age- andradiation dose-related: 1) alterations in the numberof circulating CD34+ HSCs; 2) increases in frequencies of CD34+ HSCs that carry DNA damage
and senescent phenotypes; 3) decreases in telomere
lengths of circulating granulocytes among A-bomb
survivors, which support the hypothesis that
A-bomb irradiation accelerates aging of the hematopoietic system; and 4) decreases in the frequency
of T-cell progenitors in circulating CD34+ HSCs, tosupport the hypothesis that A-bomb irradiation
accelerates the age-associated decline of T lymphopoiesis. For assessments of biological endpoints
involved in these working hypotheses, we havedeveloped a number of methods. Because CD34+
HSCs are a very small population in the blood cells
and because the blood volume we can obtain from
AHS participants is limited, establishment of sensitive and reliable assays has been required. Examples of such methods involve cell-sorting-based
limiting-dilution assays to evaluate hematopoietic
colony formation abilities of HSCs, which facilitated evaluation of age-dependent alterations infrequencies of T- and NK-cell progenitors in circulating CD34+ HSCs of healthy volunteers (manuscript in preparation). Upon establishment of theassay methods, measurements in the AHS participants were initiated in July 2011 and are scheduled
to be completed in 2013.
In order to obtain a better understanding of themechanisms involved in radiation-induced aging
acceleration in the hematopoietic system, we
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Science Articles
undoubtedly need to complement our human studies with suitable animal model systems. To investigate the process of hematopoietic and immune
reconstitution following radiation-induced damage,this project uses a number of mouse models. Questions to be addressed in those mouse models are
how irradiation modulates hematopoietic functions, myeloid and lymphoid cell differentiation,
inflammatory responses, and genomic stability.
Effects of radiation and aging on bone marrowstromal and thymic epithelial cells are also being
analyzed in mouse models. Analyses of the characteristics and functions of hematolymphoid cells
reconstituted in irradiated hosts include investigations in SCID-hu mice containing human blood
cells; this model is thought to be useful to evaluate
effects of low-dose radiation to which a large number of A-bomb survivors were exposed.2 The animal experiments are being conducted by collaborators outside RERF, i.e., researchers in Memorial
Sloan-Kettering Cancer Center, University ofGeorgia, Japan National Institute of Health Sciences, and Chiba University, but with close discussion between RERF members and the collaborators.
Project 2: Effects of ionizing radiation exposureand aging on DCs and their precursors
This study will examine effects of ionizing radiation exposure and aging on DCs and their precursors. DCs are crucial in triggering primary immune
responses against pathogens, but also in the controlof adaptive immunity, and may therefore be
involved in impaired T-cell responsiveness andimpaired homeostasis with aging in irradiated individuals. We thus hypothesize that A-bomb irradiation affects innate and adaptive immunity, possiblyby altering DC populations toward a T-cell suppressor phenotype. The working hypotheses in thestudies on AHS participants are therefore that there
are age- and radiation dose-related: 1) significant
alterations in the number of circulating conventional DCs (cDCs) and plasmacytoid DCs (pDCs);
2) increases in the production of immunosuppressive cytokines from DCs; and 3) increases in
expression levels of genes involved in DC-mediated immunosuppressive effects on T cells. In collaboration with Duke University, we establishedmicroassay systems using custom polymerase
chain reaction (PCR) and cytokine arrays for evaluation of human DC functions. DC measurements in
the AHS participants were also initiated in July
2011 and scheduled to complete in 2013. Experiments with mouse models are also being conductedby collaborators in Keio University and the University of Tokushima, to better understand the innate
and adaptive immune systems following radiationinduced damage of the hematopoietic system.
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28
Project 3: Effects of ionizing radiation exposureand aging on vaccination responses and investigation of methods to augment immune responses
The primary purpose of this study is to assessradiation effects on the immune system in terms of
the immune response to influenza vaccine among
AHS subjects. This study uses a prospective designfor the recruitment of study subjects, vaccinationby collaborating attending doctors, and collectionof blood samples before and after vaccination. The
primary endpoint is the change in anti-influenza
virus antibody titer levels from before to three
weeks after vaccination. Secondary endpoints
include levels of supernatant cytokines and inflammation-related proteins and their mRNA expression in flu-vaccine-stimulated blood mononuclear
cells and phenotypes of lymphocyte and DC subsets. Those parameters will be analyzed in relation
to age and dose of prior radiation exposure. Mechanistic studies are also being conducted in vivo inmouse models by collaborators at the University of
Arizona.
In 2010, we conducted a pilot study withrecruitment of 50 AHS subjects and young inhouse volunteers (controls) for evaluation of subject-participation rate and for the development andvalidation of assay methods. The pilot was successful and achieved a high subject-participation rate,with full cooperation from the Hiroshima City
Medical Association (HCMA) and the attending
physicians. The sera obtained before and three
weeks after vaccination from 50 AHS subjects and20 younger in-house volunteers (controls) wereused to assess anti-influenza virus antibody levels.
The hemagglutination inhibition titers to A/H1N1
and A/H3N2 antigens in post-vaccination were significantly higher in a majority of AHS subjects andyoung controls than those in pre-vaccination. Preand post-vaccination frequencies of lymphocyte
and DC subsets were determined, and most of
those were found to be substantially unchanged
between pre- and post-vaccination. Of interest is,however, that the post-vaccination frequencies ofTh1 and Tc1 (but not Th2 nor Tc2) increased after
vaccination. The frequency of cDCs at post-vaccination was marginally lower than that at pre-vaccination in the AHS subjects. The frequency of cDCs
in AHS subjects was substantially unchanged
between pre- and post-vaccination, and this is also
the case in cDC and pDC frequencies in young
controls.
On the basis of this pilot study, we developed aplan for the full-scale vaccination study in FY2011
and FY2012 enrolling about 300 AHS subjects and20 young in-house volunteers. A questionnaire forthe first-year full-scale study was sent to 320 AHS
participants, and finally a total of 157 subjects havecompleted all measurements planned for the fullRERF Update Volume 23, Issue 1, 2012

Science Articles
scale vaccination study. A total of 140 attending
physicians of those study subjects played an important cooperative role in the influenza vaccinationand collection of blood before vaccination. In
FY2012, we expect to successfully conduct thesecond-year full-scale study in the same way.
Project 4: Development of an integrated scoring
system for human immune competence as it relates
to age and ionizing radiation
The objective of this study is to develop an integrated scoring system for evaluating the immunological and inflammatory status of individuals as afunction of age and radiation dose, and predicting
the effects of radiation on the immune system andsomatic mutation in exposed subjects. Our immunology study, unique to RERF, consists of repeatedobservations of various immunological parametersin A-bomb survivors with long-term follow-up.
This may demonstrate significant radiation-related
alterations in the immune system among survivors,even 65 years after the exposure to A-bomb radiations. Thus, in this study, a cross-sectional analysis
is proposed that will include about 3,600 Hiroshima
AHS subjects. A longitudinal analysis is also proposed with repeated measurements of immunological and inflammation-related markers on a subset
of 300 selected AHS subjects. Biomarkers will bemeasured using antibody chip arrays on two sets ofplasma samples collected from the 300 AHS subjects ten years apart. Telomere length assays will
also be conducted on DNA from the same 600
samples. The results will be utilized to construct anintegrated scoring system.
We have measured plasma levels of reactive
oxygen species (ROS) in 1,520 AHS subjects in
Hiroshima. The intracellular ROS (H2O2 and O2.–)levels in blood cells were also measured in 1,600
blood samples using an intracellular ROS assay
system. Twenty seven different plasma cytokines
have also been measured in 1,700 AHS subjects
using the Bio-Plex Pro cytokine assay. Lymphocyte
subset frequencies have been measured in 2,300
AHS subjects. Preliminary analyses indicated thatplasma ROS levels increased with increased radiation dose.3 The intracellular H2O2 levels in T-cell
subsets did not increase with age or radiation. The
intracellular O2.– levels increased with increased
age in any T-cell subsets examined, and thisincreasing response was also seen for increased
radiation dose in CD3, CD4, CD8, and naïve CD8
T cells.
Members of the Statistics Department and an
additional U.S. collaborator will apply sophisticated methods (e.g., Bayesian network) to develop
and evaluate the scoring system. The collection of
informed consent for this study was initiated.
Namely, we have obtained written informed conReturn to Table of Contents

29
sent for the use of donated biosamples and pastmeasurement data in this study from AHS subjects
who visited RERF for regular health examinations.
The collection of informed consent and measurements in obtained blood samples will be completed
in 2013, and then the scoring system will be established in 2014.
Project 5: A feasibility study for future analyses ofthe effects of ionizing radiation and aging on thymus architecture and function
The goal of this study is to evaluate the numbers
and quality of the thymus autopsy specimens
stored at RERF as well as at Hiroshima University
Hospital, in order to verify the feasibility of future
analyses of thymus architecture and function in
response to aging and exposure to ionizing radiation. Autopsied thymus specimens of A-bomb survivors (LSS subjects) represent a valuable andunique resource for the study of the impact ofaging and radiation exposure on the thymus and on
thymic involution. However, it has been unclear
until now how many thymus tissues are available
with sufficient quality for a future comprehensive
study, which will employ histochemical and molecular analyses. In this study, therefore, the availability and quality of thymus specimens will be surveyed among the LSS autopsy cases recorded in
the Hiroshima RERF Tissue Archives of A-bomb
survivors together with the data on age at death,radiation dose, gender, and clinical information.
Selected representative samples will be assessed
for their utility in various histochemical and molecular assays, such as staining with CD1a antibody,
TREC assay, and quantitative reverse transcript(RT)-PCR assays for selected cytokines, chemokines, and transcription factors involved in thymic
epithelial cell differentiation.
Currently, a total of 241 autopsy cases having a
thymus sample were identified (108 cases below 70
years old at death and 133 cases who died at 70
years old or older). Epidemiological and clinicalinformation of the cases such as age, gender, radiation dose, time until autopsy (elapsed time sincedeath), pathologic and clinical diagnosis, and treatment history were obtained from the RERF database and autopsy reports. Histochemical analyses(hematoxylin and eosin staining and immunohistochemical staining with antibodies to cytokeratin)
were initiated using selected samples.
Immunological phenotypes and diseases
In collaboration with the Departments of Clinical Studies and Statistics, we investigated associations of immunological phenotypes with diseasedevelopment and health status in the AHS. To
deepen the understanding of lymphocyte phenotypes related to the course of hepatitis C virus
RERF Update Volume 23, Issue 1, 2012

Science Articles(HCV) infection and progression of liver fibrosis in
A-bomb survivors, we recently compared percentages of lymphocyte subsets among three groups of
AHS populations: 162 HCV persistently infected,
145 spontaneously cleared, and 3,511 uninfectedindividuals.4 We observed increased percentages of
peripheral blood Th1 and total CD8 T cells anddecreased percentages of NK cells in the HCV persistence group compared with the other two groups
after adjustment for age, gender, and radiation
exposure dose. Subsequently, we determined that
increased Th1 cell percentages in the HCV persistence group were significantly associated with anaccelerated time-course reduction in platelet countaccelerated progression of liver fibrosis, whereas
Tc1 and NK cell percentages were inversely associated with progression. This study suggests that
Th1 immunity is enhanced by persistent HCV
infection and that measuring the percentages of
peripheral Th1, Tc1, and NK cells may help predict
progression of liver fibrosis.

30
association analyses utilize the A-bomb survivors’
stored biological materials and cumulative immunology data. The results obtained from the studies
will have the potential to contribute to the individualized prevention of radiation-associated diseases
in A-bomb survivors and also other exposed populations.

Inflammation and genomic instability
To investigate whether radiation-induced
genomic instability persisted in vivo, we quantified the number of micronucleated reticulocytes
in peripheral blood of whole-body X-irradiatedmice.5 Even one year after irradiation, mice irradiated with 2.5 Gy of X ray showed significantly
increased frequencies of micronucleated reticulocytes. The results indicate that delayed genomic
effects of irradiation on the murine hematopoietic
system can persist in vivo for prolonged periods.
To test the hypothesis that persistent inflammation may cause radiation-induced genomic
instability through elevation of inflammatory cytokine levels, we evaluated the relationship between
inflammation and genomic instability in a murine
hematopoietic system in vivo. Persistent inflammation was induced with graft-versus-host disease(GVHD) in F1 mice that received hematopoietic
cell transplantation from parent mice. Both thefrequency of micronucleated reticulocytes and thelevel of circulating TNF-α significantly increasedin the GVHD F1 mice, suggesting that inflammation manifested with an increased TNF-α level may
be involved in genomic instability.6

Cancer development and polymorphisms of immunerelated genes
Epidemiological studies have demonstrated
long-lasting impacts of A-bomb radiation on theincidence/mortality of inflammation-related cancers. Although enhanced inflammation has been
consistently observed among A-bomb survivors,roles of inflammatory responses in radiation carcinogenesis are not understood. In this study, therefore, relationships are investigated among risks ofradiation-associated cancers, individuals’ genetic
backgrounds, and A-bomb radiation exposure,focusing on polymorphisms of genes encoding
molecules that are possibly involved in immunological defenses against cancer development or in
inflammatory responses that may modify cancer
risk. Four working hypotheses are tested in thisstudy. The first hypothesis concerns the involvement of polymorphisms of genes related to innate
immunity, such as NK and toll-like receptor genes.
The second hypothesis is that cancer risk is related
to inter-individual variations in acquired immunity,
associated with HLA class I, class II, and non-classical class I genes. Persistent inflammatory status
may also be related to cancer, and the third hypothesis is that the inflammatory response of individuals in part depends on polymorphisms of inflammation-related genes encoding cytokines, chemokines,
and their receptors. The fourth hypothesis is thatpolymorphic DNA repair genes and/or drug-metabolizing enzyme genes may also be involved ininter-individual differences in susceptibility toradiation-associated cancers. We will explore candidate chromosome loci over the entire genome
with use of genome-wide single nucleotide polymorphism (SNP) arrays as well as confirm ourfindings from an “immunogene-targeting”
approach, in collaboration with researchers at the
University of Tokyo.

Immunogenome studies
Epidemiological studies have clearly demonstrated long-lasting impacts of A-bomb radiation
on human health, including dose-dependent
increases in the incidence/mortality of cancer andsome types of noncancer diseases. The immunogenome studies evaluate the genetic basis for interindividual differences in immune functions and theimpact of the genetics on susceptibility to radiation-associated diseases. The phenotype-genotype(1) CA repeat number of epidermal growth factor
receptor (EGFR) gene and lung cancer7
We carried out a case–cohort study within the
AHS cohort to evaluate a possible association of
CA repeat polymorphism of EGFR gene with lungcancer risk in A-bomb survivors. By dividing study
subjects into Short and Long genotypes, defined as
the summed CA repeat number of two alleles ≤37
and ≥38, respectively, we found that prior radiation
exposure significantly enhanced lung cancer risk of

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RERF Update Volume 23, Issue 1, 2012

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31

survivors with the Long genotype, whereas the risk
for the Short genotype did not show any significant
increase with radiation dose, resulting in indistinguishable risks between these genotypes at a highradiation dose.
(2) Evaluation of case-cohort study design to analyze gene-environment interactions
In collaboration with the Department of Statistics, conventional methods of case-cohort study
design and analysis were evaluated for the studies
of gene-environment interactions.8(3) IL18 polymorphisms and colon cancer
We identified two major haplotype alleles(IL18-AT, IL18-CG), which comprise two htSNPs
located in the promoter region of IL18. A casecontrol study within the AHS cohort was conducted
to evaluate risks of colorectal cancer for both IL18
haplotypes and radiation exposure, using 210 casesand 843 controls. We found the following: 1) radiation exposure significantly enhanced the risk ofcolon cancer but not rectum cancer; 2) individuals
harboring homozygous IL18-CG alleles showed asignificantly increased risk of colon cancer, compared with those harboring at least one IL18-AT
allele; and 3) a significant gene-radiation interaction was found: Colon cancer risk for homozygote
IL18-CG alleles drastically increased when
exposed to the highest radiation dose category(>0.7 Gy).
(4) IL10 polymorphisms and stomach cancer
We found that, although the overall risk of stomach cancer significantly increased with radiationdose, this risk in both radiation-exposed and nonexposed survivors was greatly modulated by IL10
haplotypes. We further investigated whether
genetic risk of stomach cancer was modified byradiation dose in different pathological types, i.e.,
the intestinal and diffuse types. A preliminary
study showed that risk of the intestinal type stomach cancer was modulated by IL10 haplotypes but
not much by radiation exposure, while risk of the
diffuse type was modulated by radiation exposureand also by IL10 haplotypes only at a high radiation dose.
(5) NKG2D polymorphisms and HCV-related hepatitis and hepatocellular carcinoma
NKG2D is a primary activating receptor thattriggers cell-mediated cytotoxicity in NK cells
against tumor and virus-infected cells. We previously identified the NKG2D haplotypes in the natural killer gene complex region on chromosome
12p. Two major haplotype alleles, LNK1 and
HNK1, were closely related to low and high natural
cytotoxic activity phenotypes, respectively.9 FurReturn to Table of Contents

Figure 2. Genotypes associated with cell-surface NKG2D
expression levels in human peripheral blood CD8
T and NK cell populations

thermore, the haplotype of HNK1/HNK1 hasrevealed a decreased risk of cancer compared with
LNK1/LNK1.9 Further, using flow cytometry, weevaluated the functional effects of NKG2D haplotypes and five htSNPs in terms of the cell-surface
expression of NKG2D protein on NK and CD8 T
cells of peripheral blood among 732 atomic-bomb
survivors. 10 NKG2D expression on NK cells
showed significant increases, in the order of LNK1/
LNK1, LNK1/HNK1, and HNK1/HNK1 haplotypes (Figure 2), or with major homozygous, heterozygous, and minor homozygous genotypes forindividual htSNPs (p for trend = 0.02–0.003). The
same trend was observed for NKG2D expression
on CD8 T cells. Our findings indicate that theNKG2D haplotypes are associated with the expression levels of NKG2D protein on NK and CD8 T
cells, resulting in inter-individual variations inhuman cytotoxic response.
We also conducted a case-control study of persistent HCV infection within the AHS cohort,selecting 134 cases with persistent HCV infection
and 107 controls with HCV clearance. We observed
significant effects of NKG2D haplotypes on persistent HCV infection only among female subjects,
not male. The rate of HCV clearance is significantly lower (43%) in individuals having at least
one particular NKG2D allele relating to low NK
activity than the rate (60%) in those having highNK activity-relating NKG2D alleles (odds ratio[OR] 3.7, 95% confidence interval [CI]: 1.1–12.5).
A case-cohort study of hepatocellular carcinoma
comprised 115 cases and a sub-cohort of 2,132
within the AHS cohort. When dividing the study
subjects into combinations of three exposure-dose
categories (non-exposure, <0.7 Gy exposure, ≥0.7
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Gy) and two NKG2D haplotype categories, risk ofhepatocellular carcinoma was the highest for individuals who have at least one low NK activityrelating NKG2D allele and most heavily exposed toradiation (≥0.7 Gy) (relative risk 4.3, 95% CI: 1.0–
18.0).
(6) Polymorphisms of DNA repair genes, somatic
mutation, and cancer
It is known that the erythrocyte glycophorin A(GPA) mutation assay can detect erythrocyte
mutant phenotypes that are derived from mutations
that occurred by exposures to mutagens or gene
replication errors in hematopoietic cells. Based ona prospective cohort study, we have shown that
there are large individual variations as well as aradiation-dose-dependent increase in GPA mutant
frequency among A-bomb survivors and that cancer incidence is higher in persons who have higher
radiation-induced mutation frequencies.11 In order
to investigate genetic polymorphisms underlying
individual variation in the sensitivity to radiationinduced genetic damage in the hematopoietic system, we are analyzing associations between genotypes of various DNA repair genes, GPA mutant
frequency, and cancer development among AHS
subjects. Regression analyses of the p53BP1 haplotypes (GGC versus TCA) showed that although
there was no association between p53BP1 haplotyping and cancer incidence the dose-response
curve of GPA Mf significantly differed by the haplotypes (manuscript in preparation).
Diabetes mellitus (DM) and polymorphisms of
HLA-related genes
The purpose of this study is to assess the effectof radiation and various genetic factors on the riskof DM in the AHS cohort, and determine whether
differences in frequencies of any particular genotypes between Hiroshima and Nagasaki survivors
may account for why a significant association
between risk of DM and radiation dose is observedin Hiroshima survivors but not in Nagasaki survivors. Although early studies of A-bomb survivors did not show associations between radiation
exposure and a risk of DM, data on AHS subjects
in 1992–1994 indicated a significant positive
radiation-DM association in Hiroshima but not in
Nagasaki, after adjusting for sex, age, and bodymass index. This somewhat puzzling finding may
reflect genetic differences between the Hiroshima
and Nagasaki populations. Our preliminary results
suggest that radiation may persistently impair
immune responses, and that the radiation-DM
association is especially relevant to a sub-group of
A-bomb survivors who have a specific HLA class
II haplotype. Those results suggest that the effectsof radiation on the development of DM may vary
Return to Table of Contents

according to genetic background.12 We have identified DQA1 and DRB1 genotypes and analyzed
the relationships between HLA-related genetic
factors, risk of DM, and radiation dose in 711 DM
patients (483 and 228 in Hiroshima and Nagasaki,
respectively) and 1,878 controls (966 and 912 inHiroshima and Nagasaki, respectively). In particular, heavily exposed Hiroshima subjects with
DQA1*01:02-DRB1*15:01:01, DQA1*01:02DRB1*16:02:01, DQA1*03:01-DRB1*04:05 or
DQA1*05:01-DRB1*14:03:01 haplotype revealed
a significantly higher risk of DM than non-exposed
subjects (OR = 1.73/Gy, 95% CI: 1.36 to 2.20).
We have also genotyped 1,260 subjects based on
the TP53 Arg72Pro polymorphism. A preliminary
result suggests that the risk of DM in Hiroshima
survivors with TP53 Pro/Pro genotype was significantly enhanced by radiation exposure.
2. Oncology Studies

Aiming at clarification of mechanistic relationships between radiation exposure and cancer development, we have been analyzing molecular alterations in archival cancer tissues obtained from the
LSS subjects, especially focusing on thyroid,colorectal, and lung cancers. Our major hypothesisis that A-bomb radiation might affect various carcinogenic pathways in terms of particular genetic
and/or epigenetic alterations found in radiationexposed cancer cases. We also are evaluating epigenetic alterations in normal cells such as blood
cells, to determine whether radiation exposure
modulates aging-related epigenetic alterations that
may lead to increased risks of aging-related diseases including cancers.
Development of assay methods for molecular analyses using long-term preserved tissue specimens
Archival tissue specimens are valuable resourcesof materials for molecular biological analyses inretrospective studies, especially for molecular
oncology studies in cancer tissue specimens collected in the long term from A-bomb survivors.
However, most surgical and autopsy tissue specimens have been preserved as unbuffered formalinfixed and paraffin-embedded (FFPE) blocks forlong periods of time: DNA or RNA is often foundto degrade under such conditions. Although successful amplification with PCR is essential for
analysis of DNA and RNA extracted from archival
FFPE tissue specimens, we have often encounteredproblems with poor PCR amplification of target
fragments. To overcome this, we improved a DNA
extraction method to efficiently restore the PCR
template activity of DNA.13 Namely, the heat treatment of DNA samples in borate buffer resulted insuccessful PCR amplification of DNA fragments
ranging from 91 to 152 bp. We also established an
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Figure 3. Improvement of the sensitivity of real-time RT-PCR

improved method for efficient RT-PCR amplification of RNA extracted from archival FFPE tissues
by the elimination of RNA modification and therestoration of RNA template activity.14 Namely, thepreheating in citrate buffer (pH 4.0) of RNA
extracted from long-term preserved tissue specimens resulted in significantly increased efficiency
of RT-PCR. Improvement of the sensitivities ofreal-time PCR and real-time RT-PCR has beenachieved by reducing amplicon sizes (Figure 3).15
Thyroid cancer studies
RERF epidemiology studies have found that an
excess relative risk for PTC per Gy is remarkably
high among survivors.16,17 The data from the studies
following the Chernobyl accident also indicate astrong relationship between thyroid cancer andradiation exposure.18 Our molecular analysis on
rearrangements of RET, NTRK1, and BRAF genes,
and also point mutations of BRAF and RAS genes
in adult-onset PTC cases from the LSS cohort,found that the relative frequency of PTC cases with
RET/PTC or NTRK1 rearrangements (mainly RET/
PTC) in all available PTC cases significantly
increased with increased radiation dose, while PTC
cases with BRAF or RAS point mutations (mainly
BRAFV600E) significantly decreased.19,20 Apart fromthose PTC cases with known gene alterations, wefound that relative frequency of PTC cases with
“non-detected gene alterations”—no alterations in
RET, NTRK1, BRAF, or RAS gene—tended toincrease with increased radiation dose, showing
temporal change with a peak soon after exposureand then rapidly decreasing.20 Those findings suggested that some PTC cases with non-detectedgene alterations might be closely associated withradiation exposure, as are those with chromosomal
rearrangements.
Among 25 PTC cases (19 exposed and 6 nonReturn to Table of Contents

exposed) who carried no alterations in the RET,NTRK1, BRAF, and RAS genes, we recently founda new type of rearrangement, i.e., rearranged ALK
gene in 10 of 19 exposed PTC cases but none of 6
non-exposed cases.21 Trabecular/solid-like architectures, which are characterized by a solid and/ora trabecular appearance, were observed in 6 of 10
PTC cases with ALK rearrangements, while 11 of
80 PTC cases carrying one of the RET, NTRK1,
BRAF, and RAS gene alterations had such architectures.21 Forty-five PTC cases carrying one alteration in the RET, NTRK1, BRAF, or RAS gene havebeen thus far examined for rearranged ALK, and 43
cases were found to have no rearranged ALK, while
this first screening suggested that 2 cases possibly
carried rearranged ALK as well. The results suggestthat chromosomal rearrangements, such as RET
and ALK rearrangements, appear to play an important role in radiation-associated adult-onset thyroid
carcinogenesis.
To understand why RET and ALK rearrangements preferentially exist in high-dose radiationassociated PTC, we formulated the following
hypothesis: Ionizing radiation may confer a growthadvantage to thyrocytes with RET or ALK rearrangement. Development of an expression vectortransfection system using primary cultured mousethyroid epithelial cells is indispensable for the
future in vitro irradiation experiments to test thishypothesis. By improving the transfection system
in primary cultures, evaluation of the tumorigenic
potentials of rearranged RET and ALK is underway.
Colorectal cancer studies
Colorectal cancer has two main categories ofgenomic instability. The most common is chromosomal instability (CIN), in which the requisite
genetic events occur due to the accumulation ofchromosomal abnormalities. The other main type is
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microsatellite instability (MSI), which is a consequence of impaired recognition and repair of mismatched bases. Furthermore, in the serrated polyppathway with MSI, constitutive activation of the
MAP kinase signaling pathway that is caused bygene alterations is recognized as an early event.
More recently, the CpG island methylator phenotype (CIMP) pathway has been proposed as theprincipal underlying mechanism in MSI. In thisstudy, therefore, we are focusing on molecular
events related to those phenotypes, using archival
surgical and autopsied colorectal cancer specimens
which are preserved at RERF as well as archival
specimens thus far obtained from the Departmentof Molecular Pathology, Hiroshima University
Graduate School of Biomedical Sciences. MSI and
CIN status and their related gene alterations arebeing assessed in terms of the association withpathoepidemiological factors including radiation
dose. A pilot study identified five high-MSI coloncancer cases with the median radiation dose significantly higher than that in microsatellite stable andlow-MSI cases, along with Ras-signaling genealterations.22 The data suggest that radiation exposure may influence MSI-related colorectal carcinogenesis through genetic and epigenetic alterationsin MLH1 and Ras-signaling genes.
Lung cancer studies
Based on the hypothesis that radiation exposure
may affect the profile of genetic and/or epigenetic
alterations related to lung carcinogenesis, we are
analyzing: 1) molecular characteristics of lung cancer among A-bomb survivors; and 2) joint effectsof smoking and radiation on lung cancer. In a pilot
study, using DNA extracted from microdissected
tissue specimens, we examined allelic imbalance of
p53, p16, and RASSF1A, mutations of p53, EGFR,
and K-ras, and methylation of p16, RASSF1A, andretrotransposone LINE1 (a marker of global methylation in genomic DNA), among 38 non-small celllung cancer (NSCLC) cases (20 radiation-exposedcases and 18 non-exposed cases). Preliminary
results indicated that p53 mutation frequency andRASSF1A methylation levels in exposed NSCLC
cases compared to non-exposed NSCLC are higher
and lower, respectively, although these are not statistically significant differences. Further analyses
with increased numbers of cases are being planned
and a research protocol (RP) is under review.
Epigenetic studies
Our epigenetic studies are driven by a hypothesis that radiation may affect aging-associated epigenetic alterations potentially involved in cancer
and noncancer diseases among A-bomb survivors.
It is known that radiation affects DNA methylation
status, e.g., gender- and tissue-specific global DNA
Return to Table of Contents

hypo-methylation and p16 promoter hyper-methylation, and that similar changes appear with aging.
To test this hypothesis, therefore, we will take athree-step approach. Assessments will be conducted of: 1) aging effects in blood cells of nonAHS healthy volunteers; 2) radiation effects on
aging-related epigenetic changes in the AHS; and
3) relationships between radiation-associated epigenetic alterations and biological risk markers of
aging-related diseases among the AHS. Based on
results from the first two steps (identification of
aging- and radiation-associated changes in target
genes among particular blood cell subpopulations),
we will work closely with the Department of Clinical Studies to target disease and biomarker endpoints that appear most promising.
The first-step study is underway, using various
blood cell subsets obtained from 48 non-AHS
healthy female volunteers. We compared DNA
methylation levels between a young group comprised of 26 women at ages <35 years and an
elderly group of 22 women at ages >65 years. Innaïve CD4 T cells, granulocytes, and peripheral
blood mononuclear cells (PBMC), MyoD, hTERT,and TUSC3 methylation levels were significantly
higher in the elderly group than those in theyounger group. These two groups revealed significant differences in methylation status of HIC1,
p16, and RARb2 in naïve CD4 T cells and PBMC,
but not in granulocytes. LINE1 methylation levels
in naïve CD4 T cells and PBMC, but not in granulocytes, were significantly lower in the elderlygroup than those in the younger group. The differences in methylation status of selected genes andwhole genome between the elderly and younggroups were found as potent DNA methylation
markers related to aging effects, although such age
effects may differ by blood cell types. Based onthese preliminary results, we are preparing an RP
for the second step.
3. Biosample Collection and Storage

The effects of A-bomb radiation have been studied using many different endpoints, and measurement techniques have continuously improved overtime. In addition, studies unique to RERF involve
repeated examinations of a series of biomarkers ina fixed cohort, i.e., the AHS cohort. Therefore, it isreasonable to expect that in the future it will bepossible to study effects which we are not currently
able to assess and that more robust risk assessmentsof radiation-related diseases will become possibleon the basis of longitudinal data in the AHS cohort.
For this reason, the Immunology Laboratory in our
department has been engaging in blood sample
collection and storage under three active RPs:
1) Cryopreservation of blood mononuclear cells;2) Transformation of B cells by Epstein-Barr virus
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Science Articles
and cryopreservation of the immortalized lymphocytes; and 3) storage of blood cells and plasma.
Outlines of collections, assays, and storages ofblood samples are illustrated in Figure 4.
Approximately 2–5 × 106 mononuclear cells/
vial are cryopreserved for each donor, and 70,000
vials from a total 9,000 AHS subjects have been
stored since 1992. We confirmed that the viabilityof cryopreserved cells was more than 80% and thatthawed lymphocytes expressed normal surface
antigens and immunological functions. Immortalization of lymphocytes from 2,700 subjects was set
as the goal and has been completed. We have thus

far cryopreserved 30,000 blood sample vials from
AHS participants, including the expanded AHS
participants who were exposed to radiation at theage of nine years or younger. The PCR amplification of DNA extracted from laboratory control
blood stored at –80oC for 14 years on paper showedno recognizable degradation of DNA after the
long-term storage.
Our molecular oncology studies largely rely on
systematic collection and storage of tissue specimens from archival cancer cases among A-bomb
survivors. Pathologists in local hospitals as well as
RERF scientists contribute to collecting cancer tis-

Figure 4. Analyses and storage of blood samples in the immunology studies

Figure 5. A flow of collection and analysis of cancer tissue specimens of A-bomb survivors (thyroid cancer)
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RERF Update Volume 23, Issue 1, 2012

Science Articles
sue specimens for these studies (the collaborationis shown in Figure 5), and development of a morecomprehensive tissue specimen network is being
planned by RERF.

Collaborations
The department collaborates with the ClinicalStudies Department in sharing data on biomarker
measurements and clinical information in the AHS.
We are also collaborating with the Department of
Epidemiology for the investigation of pathological
specimens of colorectal, lung, and thyroid cancers,
and with the Statistics Department in study-designand data-analysis efforts. The Information Technology Department offers strong support to the management of research data and samples in our
department. The Departments of Radiobiology/
Molecular Epidemiology and Genetics work cooperatively in experiments using animal and radioisotope facilities as well as high-tech facilities such as
microarrays and cell sorters.
In addition to the NIAID collaborative immunosenescence project and pathological specimen
collection in collaboration with Hiroshima andNagasaki Universities and local hospitals, thedepartment also has domestic and overseas collaborative studies with a number of researchers outside RERF. For example, immunogenome studies
are conducted in collaboration with the Universityof Tokyo and Japanese National Cancer Center,and molecular oncology studies are performed incollaboration with Hiroshima and Nagasaki Universities and the U.S. National Cancer Institute(NCI).
Future Studies
The department will continue efforts to deepen
mechanistic understanding of radiation healtheffects, which is needed as a foundation for morerobust risk assessments of radiation-associated diseases along with improved prevention and treatment of these diseases.
Immunobiology studies
To further assess radiation-related immunosenescence, we will make efforts to extend the immunosenescence study project with a renewal of the
NIAID contract and plan the following studies:
1) Molecular and histological alterations in LSS
autopsied lymphoid organs, such as thymus,
bone marrow, gut-associated lymphoid tissues
and lymph nodes2) Radiation impact on aging-associated immuno-

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36
logical changes in longitudinal analyses of theAHS3) Animal model studies to understand immunological mechanisms on radiation-induced
aging-associated diseases
Immunogenome studies
The immunogenome studies will continue toseek associations between immune-related gene
polymorphisms and various immunological phenotypes that have been determined in the immunobiology studies. With use of a case-cohort study
design, factors responsible for relative risks of cancers and noncancer diseases for various radiationdose levels and genotypes will be assessed. The
following approaches will be undertaken toadvance the immunogenome studies:
1) SNP array analysis to search for the genes
responsible for radiation-related diseases
2) Incorporation of genotype data into an immune
scoring system developed in the immunosenescence study project
Oncology studies
The oncology studies will continue to investigate mechanisms of radiation-induced carcinogenesis with special reference to the role of inflammation in cancer development. In addition to analyses
of molecular alterations in thyroid, colorectal, andlung cancer tissues in the LSS, the following
approaches will be undertaken:
1) Molecular and histological alterations in precancerous tissues
2) In vitro and in vivo experiments using transgenic cells/animals
3) Evaluation of radiation effects on organ-specific stem/progenitor cells
Epigenome studies
To seek relationships between epigenetic changes
and radiation-related diseases including cancers,
oncologists and immunologists in the Departmentsof Radiobiology/Molecular Epidemiology andClinical Studies will jointly undertake the following examinations in AHS subjects:
1) Radiation effects on aging-related epigenetic
changes in blood cell populations
2) Relationships between radiation-associatedepigenetic alterations and biological risk markers of aging-related diseases
3) Epigenome alterations in association with
T-cell immunosenescence

RERF Update Volume 23, Issue 1, 2012

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37

References
1. Kusunoki Y, Hayashi T, Douple EB, Nakachi K. A special opportunity for RERF to expand studies of
immunosenescence and other late effects of acute ionizing radiation exposure in A-bomb survivors. RERF
Update 2010; 21(1):13-23.
2. Wang C, Nakamura S, Oshima M, Mochizuki-Kashio M, Nakajima-Takagi Y, Osawa M, Kusunoki Y,
Kyoizumi S, Imai K, Nakachi K, Iwama A. Compromised hematopoiesis and increased DNA damage
following non-lethal ionizing radiation of a human hematopoietic system reconstituted in immunodeficientmice. (submitted)
3. Hayashi T, Morishita Y, Khattree R, Misumi M, Sasaki K, Hayashi I, Yoshida K, Kajimura J, Kyoizumi S,
Imai K, Kusunoki Y, Nakachi K. Evaluation of inflammation status in atomic-bomb survivors with specialreference to radiation and age effects. (submitted)
4. Yoshida K, Ohishi W, Nakashima E, Fujiwara S, Akahoshi M, Kasagi F, Chayama K, Hakoda M, Kyoizumi S,
Nakachi K, Hayashi T, Kusunoki Y. Lymphocyte subset characterization associated with persistent hepatitis C
virus infection and subsequent progression of liver fibrosis. Hum Immunol 2011; 72:821-6.
5. Hamasaki K, Imai K, Hayashi T, Nakachi K, Kusunoki Y. Radiation sensitivity and genomic instability in thehematopoietic system: Frequencies of micronucleated reticulocytes in whole-body X-irradiated BALB/c and
C57BL/6 mice. Cancer Sci 2007; 98:1840-4.
6. Kusunoki Y, Hamasaki K, Koyama K, Imai K, Hayashi T, Martin PJ, Nakachi K. Increased DNA damage inhematopoietic cells of mice with graft-versus-host disease. Mutat Res 2010; 689:59-64.
7. Yoshida K, Nakachi K, Imai K, Cologne JB, Niwa Y, Kusunoki Y, Hayashi T. Lung cancer susceptibility
among atomic-bomb survivors in relation to CA repeat number polymorphism of epidermal growth factor
receptor gene and radiation dose. Carcinogenesis 2009; 30:2037-41.
8. Cologne JB, Preston DL, Imai K, Misumi M, Yoshida K, Hayashi T, Nakachi K. Conventional methods ofcase-cohort study design and analysis with application to a study of cancer and gene-environment interaction.
(submitted)
9. Hayashi T, Imai K, Morishita Y, Hayashi I, Kusunoki Y, Nakachi K. Identification of the NKG2D haplotypes
associated with natural cytotoxic activity of peripheral-blood lymphocytes and cancer immunosurveillance.
Cancer Res 2006; 66:563-70.
10. Imai K, Hayashi T, Yamaoka M, Kajimura J, Yoshida K, Kusunoki Y, Nakachi K. Effects of NKG2D
haplotypes on the cell-surface expression of NKG2D protein on natural killer and CD8 T cells of peripheral
blood among atomic-bomb survivors. Hum Immunol 2012; 73:686-91.
11. Kyoizumi S, Kusunoki Y, Hayashi T, Hakoda M, Cologne JB, Nakachi K. Individual variation of somatic genemutability in relation to cancer susceptibility: Prospective study on erythrocyte glycophorin A gene mutationsof atomic bomb survivors. Cancer Res 2005; 65:5462-9.
12. Hayashi T, Fujiwara S, Morishita Y, Kusunoki Y, Nakashima E, Nakanishi S, Suzuki G, Nakachi K, Kyoizumi
S. HLA haplotype is associated with diabetes among atomic bomb survivors. Hum Immunol 2003; 64:910-6.
13. Taga M, Eguchi H, Shinohara T, Takahashi K, Ito R, Yasui W, Nakachi K, Kusunoki Y, Hamatani K. Improved
PCR amplification for molecular analysis using DNA from long-term preserved formalin-fixed, paraffinembedded tissue specimens. (submitted)
14. Hamatani K, Eguchi H, Takahashi K, Koyama K, Mukai M, et al. Improved RT-PCR amplification formolecular analyses with long-term preserved formalin-fixed, paraffin-embedded tissue specimens. J
Histochem Cytochem 2006; 54:773-80.
15. Hamatani K, Eguchi H, Mukai M, Koyama K, Taga M, Ito R, Hayashi Y, Nakachi K. Improved method foranalysis of RNA present in long-term preserved thyroid cancer tissue of atomic bomb survivors. Thyroid
2010; 20:43-9.
16. Thompson DE, Mabuchi K, Ron E, Soda M, Tokunaga M, Ochikubo S, Sugimoto S, Ikeda T, Terasaki M,
Izumi S, Preston DL. Cancer incidence in atomic bomb survivors. Part II: Solid tumors, 1958–1987. Radiat
Res 1994; 137:S17-67.
17. Preston DL, Ron E, Tokuoka S, Funamoto S, Nishi N, Soda M, Mabuchi K, Kodama K. Solid cancer
incidence in atomic bomb survivors: 1958–1998. Radiat Res 2007; 168:1-64.
18. Astakhova LN, Anspaugh LR, Beebe GW, Bouville A, Drozdovitch VV, Garber V, Gavrilin YI, Khrouch VT,
Kuvshinnikov AV, Kuzmenkov YN, Minenko VP, Moschik KV, Nalivko AS, Robbins J, Shemiakina EV,

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Shinkarev S, Tochitskaya SI, Waclawiw MA. Chernobyl-related thyroid cancer in children of Belarus: A casecontrol study. Radiat Res 1998; 150:349-56.
19. Takahashi K, Eguchi H, Arihiro K, Ito R, Koyama K, Soda M, Cologne J, Hayashi Y, Nakata Y, Nakachi K,
Hamatani K. The presence of BRAF point mutaion in adult papillary thyroid carcinomas from atomic bomb
survivors correlates with radiation dose. Mol Carcinogeensis 2007; 46:242-8.
20. Hamatani K, Eguchi H, Ito R, Mukai M, Takahashi K, Taga M, Imai K, Cologne J, Soda M, Arihiro K,
Fujihara M, Abe K, Hayashi T, Nakashima M, Sekine I, Yasui W, Hayashi Y, Nakachi K. RET/PTC
rearrangements preferentially occurred in papillary thyroid cancer among atomic bomb survivors exposed tohigh radiation dose. Cancer Res 2008; 68:7176-82.
21. Hamatani K, Mukai M, Takahashi K, Hayashi Y, Nakachi K, Kusunoki Y. Rearranged anaplastic lymphoma
kinase (ALK) gene in adult-onset papillary thyroid cancer among atomic-bomb survivors. Thyroid 2012. (inpress)
22. Nakachi K, Hayashi T, Hamatani K, Eguchi H, Kusunoki Y. Sixty years of follow-up of Hiroshima andNagasaki survivors: Current progress in molecular epidemiology studies. Mutat Res 2008; 659:109-17.

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Human Interest Notes

In Memoriam
Remembering Dr. Itsuzo Shigematsu(25 November 1917–6 February 2012)
Toshiteru Okubo, Chairman
Although Dr.
Itsuzo Shigematsu
had always beenin good health, he
was hospitalized inTokyo on April 8,
2011, for treatmentof an aortic aneurysm and to undergo
stent insertion. Although he was recovering well after
the operation, fromDr. Itsuzo Shigematsu, giving a around November
memorial lecture at the 25th an- of last year, Dr.
niversary of the establishment of Shigematsu came
RERF, November 2000
down with pneumonia several times,
which gradually weakened him physically. Dr.
Shigematsu ultimately passed away on February
6, 2012.
Dr. Shigematsu was born in Osaka on November 25, 1917. After studying at Osaka High School(under the old Japanese education system) in
Abeno, Osaka, he matriculated to the School of
Medicine at Tokyo Imperial University. After graduating from the university in December 1931, he
was soon recruited as a naval surgeon and experienced service on a cruiser named the “Kuma,” aswell as being stationed in military bases overseas.
In 1942, when the tide of war was turning against
Japan, he served in Rabaul, Papua New Guinea, thesite of one of the bloodiest battles of the war andwhere he was when the global conflict ended.
After the war, Dr. Shigematsu worked for about
15 years in the Department of Epidemiology at the
National Institute of Public Health, where he led
Japan’s epidemiological research efforts at a time
when the field was still in its initial stages of development. During this period, he studied in the
United States, acquiring a Master of Public Health(MPH) degree from Harvard University’s graduate
school. In 1962, he was hired as a professor in public health by the Kanazawa University School of
Medicine. After working there for four years, hereturned in 1966 to the National Institute of Public
Health as chief of the Department of EpidemiolReturn to Table of Contentsogy. For the subsequent 15 years until retirement in
1981, Dr. Shigematsu assumed important positions
as an expert in public health and epidemiology,
including as a member of various governmental
councils, chief of research groups involving ‘itaiitai’ disease and research on SMON (subacute
myelo-optic neuropathy). He chaired various scientific societies, playing important roles not only inresearch but also in decision-making by thenational government.
After retiring from the National Institute of Public Health, Dr. Shigematsu was appointed as thethird chairman of the Radiation Effects Research
Foundation (RERF) in July 1981. The long-term
follow-up studies of fixed cohorts of A-bomb survivors established by the Atomic Bomb Casualty
Commission (ABCC), the predecessor of RERF,
are considered world-class models of epidemiological research. Therefore, the experience and network of connections acquired by Dr. Shigematsu, aleading expert in epidemiology, came to be fully
utilized at RERF. Needless to say, the understanding of information on health and exposure to various factors from a study population is the key togood epidemiological research. Unless the qualityof such information is high, reliable study resultscannot be obtained. ABCC-RERF has actively
tackled the work of estimating individual A-bombradiation doses, and in accordance with his beliefs
as an expert in epidemiology, Dr. Shigematsu exercised strong leadership in the establishment of adose assessment system, succeeding at introducing
the dosimetry system “DS86.” As everyone knows,

Dr. Itsuzo Shigematsu (fifth from left), toasting ABCC-RERF’s
50th anniversary with its former directors in June 1997

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Human Interest Notes
international radiation protection standards havebeen established on the basis of RERF’s reports onradiation risks using DS86. Furthermore, since
ABCC was founded in the chaotic period afterWorld War II, there were a host of problems related
to the management of the institution when ABCC
was reorganized into RERF, in terms of its locationand other aspects. Soon after arriving at RERF,
Dr. Shigematsu established a group for reviewing
the future vision of RERF, exercising effective
leadership in resolving problems involving management of the institution.
The Chernobyl accident in 1986 allowed Dr.
Shigematsu to also be active internationally in thefield of radiation epidemiology. He assumed various important positions, including as a member ofWHO’s Senior Advisory Committee, a member ofthe Main Commission and Committee 1 of theInternational Commission on Radiological Protection (ICRP), and chairman of the International
Advisory Committee on Chernobyl of the International Atomic Energy Agency (IAEA). His work inthese posts was recognized internationally.
Dr. Shigematsu’s impressive achievements arereflected in the numerous awards and honors hereceived. In Japan, for example, he received theSecond Order of the Sacred Treasure from theEmperor of Japan and the Achievement Award forPrevention of Tuberculosis. Awards granted frominstitutions overseas include the Sievert Award
from the International Radiation Protection Association, the Gold Medal from the Royal Swedish

Academy of Sciences, and the Timofeev Medalfrom the Russian Academy of Sciences. Furthermore, Dr. Shigematsu was recommended to serve
as a fellow of the Royal College of Physicians in
London, an honorary member of the Moscow
Academy of Advanced Education and Sciences,
and an honorary member of the International Epidemiology Association. When receiving suchawards and honors, Dr. Shigematsu always said
that he had been honored in that way on behalf ofeveryone involved. Dr. Shigematsu truly was
always considerate of other people’s feelings.
Much to the regret of those concerned, Dr.
Shigematsu retired from RERF in June 1997 after
serving as chairman for four terms over a period of
16 years. He was already 80 years old at that time.
However, even after retirement, he always madegreat efforts on RERF’s behalf in his position as
consultant emeritus. Furthermore, he willingly
delivered lectures and accepted the post of chair atscientific meetings. He also authored and publisheda number of books, maintaining his drive as an epidemiologist until the very end of his life.
When we lost Dr. Shigematsu, we lost a superstar in the area of public health in Japan. However,
he was able to educate and train many scientists inthe fields of epidemiology and public health, withhis last wishes now being carried on by many scientists active in the field of public health in Japan.
As one of those involved in public health, I
hereby offer my sincere prayers for the repose of
Dr. Shigematsu’s soul.

In Memoriam
Late Professor James Franklin Crow
University of Wisconsin(16 January 1916–4 January 2012)
Akio Awa, former Associate Chief of Research(Former Chief, Department of Genetics)
We recently received very sad news, which
I deeply regret having to report here. Dr. James
Crow, an authority on genetics, passed away early
this year, just before his 96th birthday. From thedays of the Atomic Bomb Casualty Commission(ABCC)—the predecessor of the Radiation Effects
Research Foundation (RERF)—Dr. Crow was a
devoted supporter of RERF’s program and consistently provided encouragement to us. I would liketo express our deepest condolences to his family.
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Dr. Crow was a trailblazer in the new discipline of genetics called
population genetics,
with his former students
now active all over theworld. Japan in particular has many geneticists
who had the pleasure ofknowing Dr. Crow perRERF Update Volume 23, Issue 1, 2012

41

Human Interest Notes
sonally, and manyof the leaders inhuman genetics inJapan were at one
time his students.
One of his wellknown publications is a booklet
titled “Genetic
Notes” (Burgess
Publishing ComDr. James F. Crow (left) and Dr. Akio pany, MinneapoAwa on the occasion of the Crow lis, Minnesota,USA). This famousCommittee meeting in 1975
publication was
written as a textbook for students, and a group of
Dr. Crow’s Japanese students translated it into
Japanese under the title “Idengaku-Gaisetsu(Outline of Genetics).” The Japanese translators of
the booklet were renowned Japanese geneticists,
the majority of whom were researchers at theJapanese National Institute of Genetics.
Population genetics is based on concepts that
dramatically advanced the ideas of Mendel’s classical genetics, and belongs to a scientific field that,combining temporal and spatial factors, analyzes
and uncovers mutual relationships among animals
and plants, as well as genetic and evolutional phenomena. Although the importance of Mendel’slaws has not been diminished, the efforts of Dr.
Crow and his students greatly expanded the concepts of these laws and thereby broadened researchpossibilities.
In addition to his research, the multi-talented Dr.
Crow was a professional viola player who served

as a member of Madison, Wisconsin’s symphonyorchestra.
I was involved in the field of cytogenetics(research involving chromosomes) for years, andhad been deeply involved in human genetics until I
retired. My main subject was the study of genetic
effects from exposure to atomic-bomb radiation,and throughout my career, Dr. Crow always provided me with support and encouragement.
On a personal note, I would like to relate the following story that for me is truly unforgettable:
In February 1975, a body known as the Crow
Committee met to determine research themes forthe new research institute after ABCC’s reorganization (present-day RERF). I made a presentation to
the committee, after which Dr. Crow commended
me with the recommendation that, “the highly successful cytogenetics program be continued, with anincrease in scientific personnel as needed (ABCC
Annual Report 1975–1976).” I felt lucky, mainly
because Dr. Crow and I were colleagues involvedin the same field of human genetics.
Being somewhat careless, I had felt unsure if mywork would meet Dr. Crow’s expectations, but myintention was to make the utmost effort. A
researcher can be a “star” one day, but a “has-been”
the next. Scientists are beings that have to fight likethere’s no tomorrow for a future that is unforeseeable.
I would like to conclude my memorial addressby dedicating the following words to Dr. Crowand his bereaved family (son Franklin C. Crowand daughters Laura J. Crow and Catherine
Rasmussen):“Thank you, Jim. Thank you indeed. Akio.”In Memoriam
Mr. Seymour Jablon(2 June 1918–9 April 2012)
Evan B. Douple, Associate Chief of Research
We received the sad news that a legendary foundation and cornerstone of the ABCC-RERF,
Seymour Jablon, died on 9 April 2012, at the age of
93. If you were to count on one hand the persons
who have had the greatest impact on the science of
the Foundation, Mr. Jablon would be among themost influential. As a research staff member of theMedical Follow-up Agency (MFUA) in the Division of Medical Sciences of the National Academyof Sciences-National Research Council (NASReturn to Table of Contents

NRC), Mr. Jablon was firstdispatched to Japan in October 1955 as one of threemembers of the “Ad Hoc
Committee for Appraisal of
ABCC Program” whichbecame known as the “Francis Committee” after thecommittee’s chairman, Dr.
Thomas Francis. The comRERF Update Volume 23, Issue 1, 2012

Human Interest Notes
mittee’s report, ABCC Unified Study Program,established the fundamental policy for the longitudinal long-term study on a fixed population understable conditions to conduct research and investigate late radiation effects from the atomic bombs.
The report contributed immensely to the promotion
and success of the research program for more than
56 years and established the Life Span Study and
Adult Health Study cohorts that are studied to thisday. The selection of the study population and therationale of its scale were epoch-making at thetime.
It was Mr. Jablon who dedicated himself toplanning and promoting the establishment of theTumor Registry in Hiroshima and in Nagasaki in
1957 and 1958 respectively and the Tissue Registry
initiated in 1973–1974, which were the first ever tobe established in Japan. The registries, which werealso part of the Unified Study Program, not only
contributed to the study of late effects of atomicbomb exposures, but also to the elevation of medical care measures in Hiroshima and Nagasaki.
After participating in the drafting of the Unified
Study Program, Mr. Jablon served two terms inJapan as Chief of the ABCC Department of Statistics, which included epidemiology and statistics,
first from 1960–1963, and later from 1968–1971.
He undertook the role of not only implementing the
program and directly providing guidance andsupervision to the administrative and research
activities of the department, but he also introduced
the first computer system in ABCC in 1962 andobtained a number of utility programs developed in
the U.S. for significantly augmenting the tabulating
and analyzing of the research data. He continued
his strong support and provided advice on the management and administration of the ABCC program,
first from 1963–1968 and 1971–1977 as the Associate Director of the NAS-NRC’s MFUA, and from1977 as Director of the MFUA.
In April 1975, Mr. Jablon participated in the
reorganization of ABCC into RERF as a member of
the U.S. government negotiation team and performed an important role as a true parent of thepresent RERF. He was also a member of the sixmember “Committee for the Scientific Review ofABCC” that was chaired by Dr. James Crow andwhich visited Japan in 1975 and drafted a detailed

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42
guideline on the research program for transition
into RERF. He retired from the NAS-NRC on
October 2, 1987 after 39 years of outstanding service and then continued to support RERF while an
Expert in the Radiation Epidemiology Branch of
the U.S. National Cancer Institute. He also served afive-year term as a member of RERF’s Board of
Directors from 1 July 1991 until 30 June 1996.
Because of his many years of promoting theexchange of scientists and research between Japanand the U.S. on the subject of the delayed medical
effects of atomic-bomb radiation, Seymour Jablon
was awarded the Third Order of the Sacred Treasure by the Emperor of Japan on 29 April 1987.
Seymour Jablon will be remembered as a distinguished and productive statistician who was also
known for his sociable and genial character. He
possessed a strong will and positive executive ability, and his character and insight were highly
respected in the U.S. where he not only exerted
great efforts for the procurement of funds andmaterials necessary for the operation of RERF, butwhere he recruited from the U.S. excellent scientists as RERF directors and researchers for thequality enhancement of the research program. His
career accomplished so much and he positively
impacted the careers of many other people who
were privileged to have known him.

Mr. Seymour Jablon (left) and Dr. Dale Preston, two generations of Statistics Department chiefs, taken at the Beebe
Symposium 2002

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Human Interest Notes

On the Occasion of My Mandatory Retirement
Yoshiaki Kodama, Chief
Department of Genetics
I first visited Hiroshima in 1979 to attend a scientific meeting. I was a research student at
Hokkaido University’s chromosome research laboratory (formerly known as the Makino study group)
while also doing some part-time work on the side.
At the meeting, I think I gave a presentation on amurine chromosome study or some similar topic.
Back then I had never imagined that I would cometo live in Hiroshima. At the end of that year, Professor Motomichi Sasaki of Hokkaido University’s
chromosome research laboratory told me that there
was a job opportunity for me at RERF. After thestart of the new year, I was asked to give a seminar
at RERF, which was a sort of final test one had togo through before being officially hired, a tradition
that is still followed at RERF. Although seminars
were usually given in English at RERF, I presented
my talk in Japanese because my English was poor.
At the seminar I was pleasantly surprised andimpressed by the presence of an interpreter (Ibelieve the interpreter was Mr. Kenji Yorichika)providing simultaneous translation. It goes without
saying that I had never had such an experience.
That evening, Dr. Akio Awa took me to a Hiroshima
Carp baseball game after dinner. We were seated in
the infield stands. It was the first live baseball gameI had ever attended in my life. I still clearly remember that the last pitcher in that game was thefamous Yutaka Enatsu. As for my seminar, it
seemed that I was given a passing score, because I
was officially hired as a research scientist at the
Cytogenetics Laboratory in July 1980.
When I joined RERF, I was the most juniorresearch scientist at the laboratory, and I continued
to hold that “junior” title for roughly the next 20
years. As new “junior” research scientists subsequently joined the laboratory, I started to be categorized as a senior research scientist. Looking back,the past 31 years and five months have flown by
quickly. For those 30 years or so, I have been
blessed with so many good people—outstanding
teachers and mentors, highly capable juniorresearch scientists, and technical and administrative staff who have provided excellent support. I
truly consider myself a lucky man, and I cannot
thank those people enough. Without mentioning

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individual names, I hereby express my sincerest
appreciation to all of them.
The RERF Cytogenetics Laboratory has had
eight research scientists who came from the same
Hokkaido University chromosome research laboratory. Back then, that laboratory was the only one
studying chromosomes in Japan and the only
source of chromosome researchers. People called
us the “Hokkaido mafia.” Dr. Awa was the first tocome to RERF and I was the last (the 8th person).
In the latter 1960s, the pioneer days of the Cytogenetics Laboratory, Dr. Awa and others worked hardto establish the Giemsa staining-based detection
method for identification of stable chromosome
aberrations for estimation of exposure doses. In the
1990s this detection method was replaced by the
FISH (fluorescence in situ hybridization) method,which is still used today. These research results
have been very important in studying human healtheffects from atomic-bomb radiation, proving thatthe direction set by our predecessors was correct.
As someone who has followed this course, I am
truly grateful to such individuals.
Although I have completed one chapter of mycareer with my mandatory retirement, I will startanother chapter at RERF as a fixed-term researchscientist. I truly hope to be able to convey myknowledge and expertise gained at RERF to thenext generation of research scientists.

RERF Update Volume 23, Issue 1, 2012

44

Human Interest Notes

Taking Early Retirement
Saeko Fujiwara, former Chief
Department of Clininical Studies, Hiroshima
After taking early retirement from the Radiation Effects Research Foundation (RERF) this past
March, I assumed the position of Assistant Director
at the Health Management and Promotion Center,
Hiroshima Atomic Bomb Casualty Council, working on health examinations offered to A-bomb survivors and local citizens.
I joined RERF in 1979. I feel very fortunate tohave worked with so many distinguished researchers and staff members there. Those who assisted
me with my experiments late into the night when I
had just joined the foundation (I was in charge of
immunological experiments at that time) and those
who gave me a helping hand regarding mattersbeyond the realm of work are still like older brothers and sisters to me even though they retired fromRERF long ago. Two years after I entered the foundation, Dr. Itsuzo Shigematsu assumed the positionof RERF Chairman. After a short time, Dr. Kazunori
Kodama returned to RERF following his studies in
the U.S. Furthermore, Dr. Yutaka Hosoda joined
RERF as Chief of the Department of Clinical Studies, infusing the department with great energy.
Before that time, the Department of Medicine(name of the department until March 31, 1985) performing only health examinations was consideredenough, but the department transformed itself intoa research department, where I participated in several research projects regarding the association of
immunological markers and hyperparathyroidismwith radiation exposure. Under the guidance of Dr.
Shigematsu, epidemiological projects addressing
osteoporosis and dementia were initiated as part ofresearch into radiation exposure and aging. Dr.
Shigematsu introduced me to researchers whoplayed leading roles in the osteoporosis researchcommunities in Japan and the U.S., providing mewith opportunities to participate in, and present myresearch at meetings and scientific symposiums
that were frankly too advanced for my young age
and meager scientific achievements at that time. As
a result, however, I was able to gradually convince
the clinical researchers in the area of osteoporosis
regarding the importance of epidemiology and thevalue of RERF’s research activities, borrow expensive equipment, and receive various forms of support. In this way, epidemiological research ofosteoporosis became my life’s work.
RERF is said to be a treasure trove of radiation
information, but the data accumulated thus far
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have come fromthe day-to-day efforts of past RERF
research scientists
and employees. I
tell newly hired
research scientists
to sow seeds eventhough they might
not be able to reap
the fruits of suchlabor. I myself
feel proud to havebeen involved in
the launching of the clinical study of the childrenof A-bomb survivors. Progress in the preparation
for the clinical study was very haphazard, but I feelthat those who worked together for this purpose
became like fellow soldiers rather than co-workers.
With my promotion to assistant department
chief and department chief, I had to supervise theentire department and its future, instead of thinking of only my own research. For me, however, thepresence of employees who enthusiastically dealt
with the Adult Health Study (AHS) participants
provided me with strong emotional support. I
would therefore like to express my deep appreciation to fellow staff members for their sympathetic
and courteous support and efforts to create a comfortable work environment.
I was born and raised in Hiroshima, and mymother and grandparents were A-bomb survivors.
In my childhood, my grandfather, sister, and I
never failed to attend the Hiroshima Peace Memorial Ceremony held every August 6. Thanks tothe cooperation of AHS participants, I have beenable to work at RERF on studies of interest to me
over the years. In the hope that I can contributeto enhancement of the health of elderly A-bomb
survivors, I thus decided to work for the Hiroshima
Atomic Bomb Casualty Council.
Since the Council and RERF share the same
objective of working for the benefit of the A-bomb
survivors, I hope that the relationship between
the two organizations can be further enhancedin the future. I ask for everyone’s continued cooperation toward meeting that goal.
I close by expressing my heartfelt appreciation
to the entire RERF staff for their consistent andvaried support over so many years.
RERF Update Volume 23, Issue 1, 2012

45

Facts and Figures

Accession Number of Scientific
Manuscripts Reaches 1,000
When an RERF research scientist has prepared amanuscript for publication, they are required tosubmit the manuscript to the RERF Scientific
Reports Review Committee (SRRC). That committee assigns an “accession number” to the manuscript in chronological order and conducts a preliminary review that includes sending it internallyto two RERF scientists and externally to one or two
experts in the subject area in institutions outside of
RERF and Japan. When the authors receive theresulting reviews, they respond to the concerns,
questions, recommendations, and other issues. The
process results in an improvement in the quality of
the RERF manuscripts, provides review experienceto the RERF scientists, and we assume that it
results in an improved acceptance rate.
The ABCC records show that the review process
originated with the establishment of the Scientific
Manuscript Review Board in February of 1974.
The first Board included Gilbert W. Beebe as oneof the seven members and it was chaired by Isamu
Nagai, Acting Associate Director of ABCC. When
the ABCC became the RERF in 1975, the assignment of accession numbers continued. Early in
2012, the chair of the SRRC, Evan B. Douple,
noticed that the accession numbers were approaching 1,000. He decided that he would provide a freedinner to the authors who submitted the manuscript

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with assigned accession number 1,000. He elected
not to tell RERF’s scientists in advance (and hopedthat the number of authors would not be excessively large!). On February 2, the 1,000th accession
number was assigned when the manuscript “Longterm follow-up of atomic bomb survivors” arrived
from the Department of Epidemiology’s Ritsu
Sakata, Eric J. Grant, and Kotaro Ozasa. (see photograph). The published manuscript can be foundin the journal Maturitas 72(2):99–103 (2012).

Dr. Ritsu Sakata (second from left), holding the RERF scientific report approval form with the accession number
1,000, joined by Chairman Toshiteru Okubo (far left), andher co-authors Drs. Eric J. Grant (second from right), andKotaro Ozasa (far right)

RERF Update Volume 23, Issue 1, 2012

46

Research Protocol and Recent Publications

Research Protocol Approved in
November 2011–April 2012

Recent Publications

RP 1-12 Development of an Archival System
for Surgical Cancer Samples from Atomicbomb Survivors
Ozasa K, Sugiyama H, Soda M, Yasui W, Arihiro K,
Fujihara M, Arita K, Nishisaka T, Matsuura H,
Nakashima M, Shigematsu K, Takahara O, Kusunoki
Y, Katayama H, Suyama A
The latest paper regarding the number of solidcancer cases in the Life Span Study (LSS) cohort
between 1958 and 1998 reported it as 17,448, of
which the majority of cases requiring surgical procedures are believed to have undergone surgery at
major hospitals in Hiroshima and Nagasaki. Suchsurgical cancer samples (in paraffin blocks) aremaintained independently at such hospitals. Some
hospitals, however, are forced to consider discarding the samples due to the lengthy storage they
have committed to and the difficulty they have insecuring storage space. In order to carry out pathological studies, such as in-depth molecular biological research on radiation carcinogenesis in the LSS
cohort, long-term storage of such samples needs tobe assured. The objective of this study is to develop
an archival system for surgical cancer samples
from atomic-bomb survivors in collaboration withpathologists of the major hospitals in Hiroshima
and Nagasaki. For development of this system, surgical samples from the LSS cohort members stored
at each hospital will be identified and reviewed fortheir storage status and usability in future studies.
Upon identification of such samples, each hospitalwill be requested to store them over an extended
period of time. When it becomes difficult for a hospital to continue maintaining the samples, they willbe transferred to and stored at RERF. In addition tothis research protocol (RP)’s collaborating investigators and their organizations, other major hospitals and their pathologists in Hiroshima andNagasaki will be requested to participate in this RP.
RERF will create and manage the database about
all stored samples. This RP determines the procedures of collaborating research projects in which
the storage samples will be used and the guidelines
for the utilization, and the participants in this RP
should respect them.

Adams MJ, Grant EJ, Kodama K, Shimizu Y,
Kasagi F, Suyama A, Sakata R, Akahoshi M:
Radiation dose associated with renal failure mortality: A potential pathway to partially explainincreased cardiovascular disease mortality
observed after whole-body irradiation. Radiat
Res 2012 (February); 177(2):220-8. (RERF
Report 9-11)(Japanese): the original article is in Japanese.

Chen J, Kerr GD, Cullings HM: A comparison oforgan doses between mathematical and voxel
phantoms with the DS02 photon fluences. Radiat
Prot Dosimetry 2012 (January); 149(1):49-55.
(RERF Report 22-11)
Cologne JB, Grant EJ, Nakashima E, Chen Y,
Funamoto S, Katayama H: Protecting privacy ofshared epidemiologic data without compromising analysis potential. J Environ Public Health2012 (February); Vol. 2012, Article ID 421989, 9
pages, 2012. doi:10.1155/2012/421989. Epub
only (RERF Report 2-06)
Cullings HM: Recommended improvements to theDS02 dosimetry system’s calculation of organ
doses and their potential advantages for the
Radiation Effects Research Foundation. Radiat
Prot Dosimetry 2012 (January); 149(1):2-14.
(RERF Report 24-11)
Cullings HM, Kawamura H, Chen J: Body andorgan dimensions of the 1945 Japanese population used in dosimetry system DS86 anddata available for an expanded series of phantoms. Radiat Prot Dosimetry 2012 (January);
149(1):35-42. (RERF Report 23-11)
Fattibene P, Wieser A, Adolfsson E, Benevides LA,
Brai M, Callens F, Chumak V, Ciesielski B, Della
Monaca S, Emerich K, Gustafsson H, Hirai Y, etal.: The 4th international comparison on EPR
dosimetry with tooth enamel. Part 1: Report on
the results. Radiat Meas 2011 (May); 46:765-71.
Hida A, Akahoshi M, Takagi Y, Imaizumi M, Sera
N, Soda M, Maeda R, Nakashima E, Ida H,
Kawakami A, Nakamura T, Eguchi K: Lipid
infiltration in the parotid glands: A clinical manifestation of metabolic syndrome. Exp Clin Endocrinol Diabetes 2012 (February); 120(2):110-5.
(RERF Report 14-08)
Imaizumi M, Sera N, Ueki I, Horie I, Ando T, Usa
T, Ichimaru S, Nakashima E, Hida A, Soda M,

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RERF Update Volume 23, Issue 1, 2012

47

Recent Publications
Tominaga T, Ashizawa K, Maeda R, Nagataki S,
Akahoshi M: Risk for progression to overt hypothyroidism in an elderly Japanese population
with subclinical hypothyroidism. Thyroid 2011
(November); 21(11):1177-82. (RERF Report
10-10)
Kodama K, Ozasa K, Okubo T: Radiation and cancer risk in atomic-bomb survivors. J Radiol Prot
2012 (March); 32(1):N51-4. doi:10.1088/09524746/32/1/N51 (Special section: Selected articles from Proceedings of the International Expert
Symposium in Fukushima: Radiation and Health
Risks, 11–12 September 2011)
Masunari N, Fujiwara S, Kasagi F, Takahashi I,
Yamada M, Nakamura T: Height loss starting in
middle age predicts increased mortality in theelderly. J Bone Miner Res 2012 (January);27(1):138-45. (RERF Report 2-11)
Nakamura N: Genetic effects of radiation. Nippon
Rinsho [Jpn J Clin Med] 2012 (March);
70(3):457-60. (Japanese)
Nakamura N: Cancer risks following exposure
to ionizing radiation. Surgery Frontier 2011
(December); 18(4):100-1. (Japanese)
Nakamura N, Hirai Y, Kodama Y: Gamma-ray andneutron dosimetry by EPR and AMS, using tooth
enamel from atomic-bomb survivors: A mini
review. Radiat Prot Dosimetry 2012 (January);
149(1):79-83. (RERF Report 26-11)
Neriishi K: Cataract: Based on A-bomb survivor
studies. Nippon Rinsho [Jpn J Clin Med] 2012
(March); 70(3):441-5. (Japanese)
Neriishi K, Monzen Y, Okamoto N: Radiation
effects on pregnant women, fetuses, and children. Nippon Rinsho [Jpn J Clin Med] 2012
(March); 70(3):451-6. (Japanese)
Ohishi W, Chayama K: Prevention of hepatitis B
virus reactivation in immunosuppressive therapy
or chemotherapy. Clin Exp Nephrol 2011 (October); 15(5):634-40.
Ohishi W, Fujiwara S, Cologne JB, Chayama K:
Effects of radiation exposure and lifestyle on riskof non-B, non-C hepatocellular carcinoma.
Shokaki Naika [Jpn J Gastroenterol] 2011 (October); 53(4):453-8. (Japanese)
Okubo T: Epidemiological studies: From experience in Hiroshima and Nagasaki to Fukushima.
Igaku no Ayumi [J Clin Exp Med] 2011 (DecemReturn to Table of Contentsber); 239(10):995-1000. (Japanese)
Okubo T: Radiation risk studies and radiation protection limits. Sanfujinka no Jissai [Obstet Gynecol Prac] 2011 (December); 60(13):2055-61.
(Japanese)
Ozasa K: Health effects of atomic-bomb radiationof Hiroshima and Nagasaki. Nogyo to Keizai[Agriculture & Economics] 2012 (January);
78(1):53-60. (Extra edition of January, 2012)(Japanese)
Ozasa K: Cohort studies of the atomic bomb survivors at the Radiation Effects Research Foundation. Nippon Rinsho [Jpn J Clin Med] 2012
(March); 70(3):399-404. (Japanese)
Ozasa K: Epidemiological studies of the atomic
bomb survivors in Hiroshima and Nagasaki.
Kyo-fu Idai Shi [J Kyoto Pref Univ Med] 2011
(December); 120(12):903-11. (Japanese)
Ozasa K, Shimizu Y, Suyama A, Kasagi F, Soda M,
Grant EJ, Sakata R, Sugiyama H, Kodama K:
Studies of the mortality of atomic bomb survivors, Report 14, 1950–2003: An overview ofcancer and noncancer diseases. Radiat Res 2012
(March); 177(3):229-43. (RERF Report 4-11)
Sakata R, Shimizu Y, Soda M, Grant EJ, Sugiyama
H, Pham TM, Hsu WL, Suyama A, Ozasa K.
Recent RERF epidemiological studies of an
atomic bomb (A-bomb) survivor cohort: Early
onset of menopause observed among A-bomb
survivor females. Nakashima M, et al., eds. A
New Challenge of Radiation Health Risk Management. Proceedings of the 6th International
Symposium of Nagasaki University Global COE
Program “Global Strategic Center for Radiation
Health Risk Control.” Nagasaki: Nagasaki Newspaper Publish; 2012 (March). pp 145-9.
Sakata R, Shimizu Y, Soda M, Yamada M, Hsu
WL, Hayashi M, Ozasa K: Effect of radiation onage at menopause among atomic bomb survivors. Radiat Res 2011 (December); 176(6):78795. (RERF Report 7-11)
Satoh Y, Sasaki K, Shimoichi Y, Sugita K,
Katayama H, Takahashi N: Copy-number
variations observed in a Japanese population by
BAC array CGH: Summary of relatively rare
CNVs. J Biomed Biotechnol 2012 (January);
Volume 2012, Article ID 789024, 10 pages, doi:
10.1155/2012/789024. Epub only (RERF Report
8-11)

RERF Update Volume 23, Issue 1, 2012

Recent Publications

48

Shore RE, Ozasa K, Suyama A, Fujiwara S,
Akahoshi M, Cullings HM, Kodama Y, Kodaira
M, Hayashi T, Hamatani K: Recent findings by
the Radiation Effects Research Foundation on
the health of atomic bomb survivors and theiroffspring. Nakashima M, et al., eds. A New
Challenge of Radiation Health Risk Management. Proceedings of the 6th International Symposium of Nagasaki University Global COE
Program “Global Strategic Center for Radiation
Health Risk Control.” Nagasaki: Nagasaki Newspaper Publish; 2012 (March). pp 27-33.
Takahashi I, Abbott RD, Ohshita T, Takahashi T,
Ozasa K, Akahoshi M, Fujiwara S, Kodama K,
Matsumoto M: A prospective follow-up study of
the association of radiation exposure with fatal
and non-fatal stroke among atomic bomb survivors in Hiroshima and Nagasaki (1980–2003).
BMJ Open 2012 (February); 2:e000654. Epub
only (RERF Report 13-11)

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RERF Update Volume 23, Issue 1, 2012