bluuebunny/crossref_metadata_2025 huggingface dataset:
Orphan Nuclear Receptors: Shifting Endocrinology into Reverse
Authors: Kliewer Steven A. , Lehmann Jürgen M. , Willson Timothy M.
Published: July 2002

Steroid and thyroid hormones and vitamin A metabolites (retinoids) regulate the expression of complex gene programs by binding to members of the nuclear receptor family of ligand-activated transcription factors. The nuclear receptor family also includes many “orphan” members that currently lack known ligands but that represent candidate receptors for new hormones. Recently, natural and synthetic ligands have been identified for several orphan receptors and used to dissect their biological roles. This “reverse endocrinology” strategy has resulted in the discovery of unanticipated nuclear signaling pathways for retinoids, fatty acids, eicosanoids, and steroids with important physiological and pharmacological ramifications.
The Effects of Affirmative Action
Authors: Thach Robert E.
Published: July 2002

The Shape of the River
Long-Term Consequences of Considering Race in College and University Admissions. William G. Bowen and Derek Bok. Princeton University Press, Princeton, NJ, 1998. 511 pp. $24.95. ISBN 0-691-00274-6.

The authors and their collaborators provide an in-depth, quantitative assessment of the policies and outcomes of the preferential admission of minority applicants into selective colleges and universities.
Flying Over Uncharted Territory
Authors: Wilson David Sloan
Published: July 2002

The Meme Machine
. Susan Blackmore. Oxford University Press, New York, 1999. 286 pp. $25, £18.99. ISBN 0-19-850365-2.

Psychologist Susan Blackmore attempts to develop Richard Dawkins's concept of memes into a full-fledged theory of cultural evolution.
From Hobbes to Rousseau and Back Again
Authors: Darling J. Andrew
Published: July 2002

Prehistoric Warfare in the American Southwest
. Steven A. LeBlanc. University of Utah Press, Salt Lake City, UT, 1999. 414 pp. $34.95. ISBN 0-87480-581-3.

Analyzing the distribution of warfare in time and space, LeBlanc offers a synthesis of Southwestern prehistory that attributes changes in levels of conflict to changes climatic circumstances.
In the Beginning, There Was RNA
Authors: Keller Walter
Published: July 2002

The RNA World
2nd ed. Raymond F. Gesteland, Thomas R. Cech, and John F. Atkins, Eds. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1999. 735 pp. $129. ISBN 0-87969-561-7.

Contributors to this substantial revision and updating of the acclaimed 1994 volume offer perspectives on the modern world of RNA and how it suggests that prebiotic RNA was a key stage in the evolution of life.
Gene Therapy Enters Adolescence
Authors: Leiden Jeffrey M.
Published: July 2002

The Development of Human Gene Therapy
. Theodore Friedmann, Ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1999. 743 pp. $134. ISBN 0-87969-528-5.

The contributors, leaders in the field, provide a compendium of review articles that highlights significant recent advances and illuminates the remaining obstacles to the use of gene therapies in clinical practice.
Superconductivity and the
c
Axis Spectral Weight of High-
T
c
Superconductors
Authors: Ioffe L. B. , Millis A. J.
Published: July 2002

The temperature dependence of the
c
axis spectral weight (frequency integral of the interplane conductivity) of high transition temperature (high-
T
c
) superconductors is shown to be a probe of thermal and quantal fluctuations of the phase of the superconducting order parameter. The behavior of underdoped cuprates is shown to be a natural consequence of superconducting pairing without long-ranged phase coherence. Very underdoped cuprates are found to have strong phase fluctuations, even for temperatures much less than the transition temperature.
Curing and Caring--The Long View
Authors: Pickstone John V.
Published: July 2002

Mending Bodies, Saving Souls
A History of Hospitals. Guenter B. Risse. Oxford University Press, New York, 1999. 736 pp. $39.95. ISBN 0-19-505523-3.

Weaving narratives by patients and caregivers into his detailed considerations of a dozen institutions characteristic of their time and place (ranging from ancient Greece to the era of AIDS), Risse provides a thought-provoking interpretation of the developments that have led to today's hospitals.
Congenital Nephrotic Syndrome in Mice Lacking CD2-Associated Protein
Authors: Shih Neng-Yao , Li Jun , Karpitskii Vladimir , Nguyen Ancho , Dustin Michael L. , Kanagawa Osami , Miner Jeffrey H. , Shaw Andrey S.
Published: July 2002

CD2-associated protein (CD2AP) is an 80-kilodalton protein that is critical for stabilizing contacts between T cells and antigen-presenting cells. In CD2AP-deficient mice, immune function was compromised, but the mice died at 6 to 7 weeks of age from renal failure. In the kidney, CD2AP was expressed primarily in glomerular epithelial cells. Knockout mice exhibited defects in epithelial cell foot processes, accompanied by mesangial cell hyperplasia and extracellular matrix deposition. Supporting a role for CD2AP in the specialized cell junction known as the slit diaphragm, CD2AP associated with nephrin, the primary component of the slit diaphragm.
Two Realms and Their Relationships
Authors: Anderson Craig B.
Published: July 2002

Rocks of Ages
Science and Religion in the Fullness of Life. Stephen Jay Gould. Library of Contemporary Thought (Ballantine), New York, 1999. 250 pp. $18.95, C$26.50. ISBN 0-345-43009-3.

Seduced by Science
How American Religion Has Lost Its Way. Steven Goldberg. New York University Press, New York, 1999. 230 pp. $27.95. ISBN 0-8147-3104-X.

The Sacred Depths of Nature
. Ursula Goodenough. Oxford University Press, New York, 1998. 219 pp. $24. ISBN 0-19-512613-6.

Three divergent perspectives on the relationship between science and religion. Gould argues that their domains are separate and non-overlapping. Goldberg highlights the disadvantages that have followed from religions speaking in the language of science. And Goodenough prefers a religious naturalism; she holds that an understanding of life can generate religious feelings in the absence of organized faiths.
The Brain's Number-Crunching Power
Authors: Hauser Marc
Published: July 2002

What Counts
How Every Brain Is Hardwired for Math. Brian Butterworth. Free Press, New York, 1999. 432 pp. $26. ISBN 0-684-85417-1. ()

Writing for a general audience, Butterworth marshals evidence from a wide range of studies to argue that humans are endowed with an innate number module.
Paying for Disasters
Authors: Pielke Roger A.
Published: July 2002

Disasters and Democracy
The Politics of Extreme Natural Events. Rutherford Platt
et al
. Island Press, Washington, DC, 1999. 343 pp. Paper, $35. ISBN 1-55963-696-3.

Platt and his co-authors discuss how and why the United States has come to federalize the costs of natural disasters. Their comprehensive overview is reinforced through three case studies: coastal erosion on Fire Island, New York; flooding in St. Charles County, Missouri; and earthquakes and fires in the San Francisco Bay area.
Leakage-Resistant Blood Vessels in Mice Transgenically Overexpressing Angiopoietin-1
Authors: Thurston G. , Suri C. , Smith K. , McClain J. , Sato T. N. , Yancopoulos G. D. , McDonald D. M.
Published: July 2002

Angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF) are endothelial cell–specific growth factors. Direct comparison of transgenic mice overexpressing these factors in the skin revealed that the VEGF-induced blood vessels were leaky, whereas those induced by Ang1 were nonleaky. Moreover, vessels in Ang1-overexpressing mice were resistant to leaks caused by inflammatory agents. Coexpression of Ang1 and VEGF had an additive effect on angiogenesis but resulted in leakage-resistant vessels typical of Ang1. Ang1 therefore may be useful for reducing microvascular leakage in diseases in which the leakage results from chronic inflammation or elevated VEGF and, in combination with VEGF, for promoting growth of nonleaky vessels.
Knowledge to Heal, Knowledge to Injure
Authors: Lindee M. Susan
Published: July 2002

Undue Risk
Secret State Experiments on Humans. Jonathan Moreno. Freeman, New York, 1999. 367 pp. $24.95. ISBN 0-7167-3142-8.

Moreno, a biomedical ethicist, offers a broad overview of the use of human subjects in scientific and military research in the United States since 1940. He aims to understand how (and why) scientists and administrators chose to expose people to things that could harm them.
Oxygen Isotopes and Emerald Trade Routes Since Antiquity
Authors: Giuliani Gaston , Chaussidon Marc , Schubnel Henri-Jean , Piat Daniel H. , Rollion-Bard Claire , France-Lanord Christian , Giard Didier , Narvaez Daniel de , Rondeau Benjamin
Published: July 2002

Oxygen isotopic compositions of historical emerald artifacts from the Gallo-Roman period to the 18th century indicate that during historical times, artisans worked emeralds originating from deposits supposedly discovered in the 20th century. In antiquity, Pakistani and Egyptian emeralds were traded by way of the Silk Route. Together with Austrian stones, they were the only source of gem-quality emeralds. Immediately after the discovery of the Colombian mines by Spaniards in the 16th century, a new trade route was established, first via Spain to Europe and India and then directly via the Philippines to India. Since then, Colombian emeralds have dominated the emerald trade, and most of the high-quality emeralds cut in the 18th century in India originated from Colombia.
Tales of a Talented Bird
Authors: Kako Edward
Published: July 2002

The Alex Studies
Cognitive and Communicative Abilities of Grey Parrots. Irene Maxine Pepperberg. Harvard University Press, Cambridge, MA, 1999. 446 pp. $39.95, £24.95. ISBN 0-674-00051-X.

For more than two decades, Pepperberg has worked with an individual African Grey Parrot named Alex. In this book, she describes her admirably rigorous studies of his linguistic abilities and what they might mean for our understanding of an animal mind.
Disdained by Generals
Authors: Zilinskas Raymond A.
Published: July 2002

The Biology of Doom
The History of America's Secret Germ Warfare Project. Ed Regis. Holt, New York, 1999. 267 pp. $25, C$37.50. ISBN 0-8050-5764-1.

Regis offers an account of the biological warfare programs of the United States, Canada, Japan, and the United Kingdom. He is particularly interested in the question of why biological weapons have seen so little use.
Instruments of the Revolution
Authors: Shapin Steven
Published: July 2002

Ingenious Pursuits
Building the Scientific Revolution. Lisa Jardine. Nan A. Talese (Doubleday), New York, 1999. 464 pp. $35, C$55. ISBN 0-385-49325-8. Little, Brown, London, 1999. 464 pp. £25. ISBN 0-316-64752-7.

In this accessible and lively account for non-specialists, Lisa Jardine synthesizes much recent writing by professional historians who have revised our understanding of the Scientific Revolution.
The Human Role in Environmental History
Authors: Butzer Karl W.
Published: July 2002

Human Impact on Ancient Environments
. Charles L. Redman. University of Arizona Press, Tucson, 1999. 255 pp. $45. ISBN 0-8165-1962-5. Paper, $22.95. ISBN 0-8165-1963-3.

Redman uses a range of case studies (primarily from archeology) to address key themes and issues in the human dimensions of environmental history. His broad coverage will interest anyone who is concerned about the ecological problems that confront us today.
Professor Newton's Principles
Authors: Quigg Chris
Published: July 2002

Thinking About Physics
. Roger G. Newton. Princeton University Press, Princeton, NJ, 2000. 208 pp. $24.95, £15.95. ISBN 0-691-00920-1.

Seeking to encourage thinking rather than simply doing, Roger Newton offers a thought-provoking overview of the concepts that form the framework for research in contemporary physics.
Sources of Quantum Protection in High-
T
c
Superconductivity
Authors: Anderson Philip W.
Published: July 2002

The layer-structure cuprates with high superconducting transition temperatures
T
c
exhibit a number of anomalous electronic properties in both superconducting and normal states. These anomalies are ascribed to the existence of independent spectra of excitations for charge and for spin, signaling a collective state, a “quantum protectorate.”
Crossed Nanotube Junctions
Authors: Fuhrer M. S. , Nygård J. , Shih L. , Forero M. , Yoon Young-Gui , Mazzoni M. S. C. , Choi Hyoung Joon , Ihm Jisoon , Louie Steven G. , Zettl A. , McEuen Paul L.
Published: July 2002

Junctions consisting of two crossed single-walled carbon nanotubes were fabricated with electrical contacts at each end of each nanotube. The individual nanotubes were identified as metallic (M) or semiconducting (S), based on their two-terminal conductances; MM, MS, and SS four-terminal devices were studied. The MM and SS junctions had high conductances, on the order of 0.1
e
2
/
h
(where
e
is the electron charge and
h
is Planck's constant). For an MS junction, the semiconducting nanotube was depleted at the junction by the metallic nanotube, forming a rectifying Schottky barrier. We used two- and three-terminal experiments to fully characterize this junction.
Preserving Diversity the U.S. Way
Authors: Possingham Hugh
Published: July 2002

Conserving Earth's Biodiversity, with E.O. Wilson
. Edward O. Wilson and Dan L. Perlman. Island Press, Washington, DC, 2000. CD-ROM with User's Guide. $39.95. ISBN 1-55963-773-0. CD-ROM with User's Guide and Instructor's Manual. $39.95. ISBN 1-55963-774-9.

Wilson and Perlman's introduction to biodiversity and conservation biology combines slide shows, animation, and interactive maps with a small number of interactive models and quizzes. Readers are encouraged to explore concepts and facts using links to related web sites for every topic, which are provided through the publisher's own site.
Uninterrupted MCM2-7 Function Required for DNA Replication Fork Progression
Authors: Labib Karim , Tercero José Antonio , Diffley John F. X.
Published: July 2002

Little is known about the DNA helicases required for the elongation phase of eukaryotic chromosome replication. Minichromosome maintenance (MCM) protein complexes have DNA helicase activity but have only been functionally implicated in initiating DNA replication. Using an improved method for constructing conditional degron mutants, we show that depletion of MCMs after initiation irreversibly blocks the progression of replication forks in
Saccharomyces cerevisiae
. Like the
Escherichia coli
dnaB and SV40 T antigen helicases, therefore, the MCM complex is loaded at origins before initiation and is essential for elongation. Restricting MCM loading to the G
1
phase ensures that initiation and elongation occur just once per cell cycle.
Economic Incentives for Rain Forest Conservation Across Scales
Authors: Kremen C. , Niles J. O. , Dalton M. G. , Daily G. C. , Ehrlich P. R. , Fay J. P. , Grewal D. , Guillery R. P.
Published: July 2002

Globally, tropical deforestation releases 20 to 30% of anthropogenic greenhouse gases. Conserving forests could reduce emissions, but the cost-effectiveness of this mechanism for mitigation depends on the associated opportunity costs. We estimated these costs from local, national, and global perspectives using a case study from Madagascar. Conservation generated significant benefits over logging and agriculture locally and globally. Nationally, however, financial benefits from industrial logging were larger than conservation benefits. Such differing economic signals across scales may exacerbate tropical deforestation. The Kyoto Protocol could potentially overcome this obstacle to conservation by creating markets for protection of tropical forests to mitigate climate change.
Understanding the Distribution of Near-Earth Asteroids
Authors: Bottke William F. , Jedicke Robert , Morbidelli Alessandro , Petit Jean-Marc , Gladman Brett
Published: July 2002

We have deduced the orbital and size distributions of the near-Earth asteroids (NEAs) by (i) numerically integrating NEAs from their source regions to their observed orbits, (ii) estimating the observational biases and size distribution associated with asteroids on those orbits, and (iii) creating a model population that can be fit to the known NEAs. We predict that there are ∼900 NEAs with absolute magnitude less than 18 (that is, kilometer-sized), of which 29, 65, and 6% reside on Amor, Apollo, and Aten orbits, respectively. These results suggest that roughly 40% of the kilometer-sized NEAs have been found. The remainder, on highly eccentric and inclined orbits, are more difficult to detect.
Wet and Wild
Authors: Knapp Sandra
Published: July 2002

The Wetland Centre
. The Wildfowl and Wetlands Trust. Queen Elizabeth's Walk, London SW13 9SF.
www.wetlandcentre.org.uk

This complex constructed at the site of an abandoned reservoir introduces visitors to the wildlife and habitats of wetlands from Britain and around the world.
Resurrection of Crushed Magnetization and Chaotic Dynamics in Solution NMR Spectroscopy
Authors: Lin Yung-Ya , Lisitza Natalia , Ahn Sangdoo , Warren Warren S.
Published: July 2002

We show experimentally and theoretically that two readily observed effects in solution nuclear magnetic resonance (NMR)—radiation damping and the dipolar field—combine to generate bizarre spin dynamics (including chaotic evolution) even with extraordinarily simple sequences. For example, seemingly insignificant residual magnetization after a crusher gradient triggers exponential regrowth of the magnetization, followed by aperiodic turbulent spin motion. The estimated Lyapunov exponent suggests the onset of spatial-temporal chaos and the existence of chaotic attractors. This effect leads to highly irreproducible experimental decays that amplify minor nonuniformities such as temperature gradients. Imaging applications and consequences for other NMR studies are discussed.
Mind and Medicine
Authors: Black Ira B.
Published: July 2002

The Balance Within
The Science Connecting Health and Emotions. Esther M. Sternberg. Freeman, New York, 2000. 270 pp. $24.95. ISBN 0-7167-3479-6.

Writing for a general audience, Sternberg discusses the interface between the immune and nervous systems. She blends accounts of recent experimental approaches with historical vignettes on brain-body interactions.
Replaying the Game: Hypnagogic Images in Normals and Amnesics
Authors: Stickgold Robert , Malia April , Maguire Denise , Roddenberry David , O'Connor Margaret
Published: July 2002

Participants playing the computer game Tetris reported intrusive, stereotypical, visual images of the game at sleep onset. Three amnesic patients with extensive bilateral medial temporal lobe damage produced similar hypnagogic reports despite being unable to recall playing the game, suggesting that such imagery may arise without important contribution from the declarative memory system. In addition, control participants reported images from previously played versions of the game, demonstrating that remote memories can influence the images from recent waking experience.
Films: Be Awed, Be Very Awed
Authors: Rowan Linda
Published: July 2002

SolarMax
. John Weiley, Director. Heliograph, in association with the Museum of Science and Industry, Chicago. See:
www.solarmovie.com

This IMAX film presents the sun and the story of human study of this nearest star. It uses data from the Solar and Heliospheric Observer, the National Aeronautics and Space Administration, and the European Space Agency to create its realistic images and close up portrait.
Stirred, Not Shaken
Authors: Segerstråle Ullica
Published: July 2002

The Sokal Hoax
The Sham That Shook the Academy. The Editors of Lingua Franca, Eds. University of Nebraska Press, Lincoln, NE, 2000. 283 pp. Paper, $20. ISBN 0-8032-7995-7.

This collection presents Sokal's original article on "quantum gravity," the essay in which he revealed his hoax, a broad sampling of the news coverage and opinion pieces generated by his actions, and additional commentary on the long-term meaning of the affair from a range of scholars.
Turning Blood into Brain: Cells Bearing Neuronal Antigens Generated in Vivo from Bone Marrow
Authors: Mezey Éva , Chandross Karen J. , Harta Gyöngyi , Maki Richard A. , McKercher Scott R.
Published: July 2002

Bone marrow stem cells give rise to a variety of hematopoietic lineages and repopulate the blood throughout adult life. We show that, in a strain of mice incapable of developing cells of the myeloid and lymphoid lineages, transplanted adult bone marrow cells migrated into the brain and differentiated into cells that expressed neuron-specific antigens. These findings raise the possibility that bone marrow–derived cells may provide an alternative source of neurons in patients with neurodegenerative diseases or central nervous system injury.
Fluoroquinolone Resistance in Anaerobic Bacteria following Exposure to Levofloxacin, Trovafloxacin, and Sparfloxacin in an In Vitro Pharmacodynamic Model
Authors: Ross Gigi H. , Wright David H. , Hovde Laurie Baeker , Peterson Marnie L. , Rotschafer John C.
Published: July 2002

This investigation explored pharmacodynamic characteristics of fluoroquinolones against
Bacteroides thetaiotamicron
and the potential for development of resistance. An in vitro model was used to generate kill curves with three fluoroquinolones at various area under the concentration-time curve (AUC)/MIC ratios. Concentration-independent killing was observed. Increases in MICs were noted following exposure to fluoroquinolones at AUC/MIC ratios of 6 to 14.
Branched-Chain Amino Acid Biosynthesis Is Essential for Optimal Growth of
Streptococcus thermophilus
in Milk
Authors: Garault P. , Letort C. , Juillard V. , Monnet V.
Published: July 2002

Lactic acid bacteria are nutritionally demanding bacteria which need, among other things, amino acids for optimal growth. We identified the branched-chain amino acid (BCAA) biosynthesis pathway as an essential pathway for optimal growth of
Streptococcus thermophilus
in milk. Through random insertional mutagenesis, we isolated and characterized two mutants for which growth in milk is affected as a consequence of
ilvB
and
ilvC
gene interruptions. This situation demonstrates that the BCAA biosynthesis pathway is active in
S. thermophilus
. BCAA biosynthesis is necessary but not sufficient for optimal growth of
S. thermophilus
and is subject to retro-inhibition processes. The specificity of the BCAA biosynthesis pathway in
S. thermophilus
lies in the independent transcription of the
ilvC
gene encoding a keto acid reductoisomerase acting on acetolactate at the junction of the BCAA and acetoin biosynthesis pathways. The possible advantages for
S. thermophilus
of keeping this biosynthesis pathway active could be linked either to adaptation of the organism to milk, which is different than that of other dairy bacteria, or to the role of the pathway in maintaining the internal pH.
Successional Development of Sulfate-Reducing Bacterial Populations and Their Activities in a Wastewater Biofilm Growing under Microaerophilic Conditions
Authors: Ito Tsukasa , Okabe Satoshi , Satoh Hisashi , Watanabe Yoshimasa
Published: July 2002

A combination of fluorescence in situ hybridization, microprofiles, denaturing gradient gel electrophoresis of PCR-amplified 16S ribosomal DNA fragments, and 16S rRNA gene cloning analysis was applied to investigate successional development of sulfate-reducing bacteria (SRB) community structure and in situ sulfide production activity within a biofilm growing under microaerophilic conditions (dissolved oxygen concentration in the bulk liquid was in the range of 0 to 100 μM) and in the presence of nitrate. Microelectrode measurements showed that oxygen penetrated 200 μm from the surface during all stages of biofilm development. The first sulfide production of 0.32 μmol of H
2
S m
−2
s
−1
was detected below ca. 500 μm in the 3rd week and then gradually increased to 0.70 μmol H
2
S m
−2
s
−1
in the 8th week. The most active sulfide production zone moved upward to the oxic-anoxic interface and intensified with time. This result coincided with an increase in SRB populations in the surface layer of the biofilm. The numbers of the probe SRB385- and 660-hybridized SRB populations significantly increased to 7.9 × 10
9
cells cm
−3
and 3.6 × 10
9
cells cm
−3
, respectively, in the surface 400 μm during an 8-week cultivation, while those populations were relatively unchanged in the deeper part of the biofilm, probably due to substrate transport limitation. Based on 16S rRNA gene cloning analysis data, clone sequences that related to
Desulfomicrobium hypogeium
(99% sequence similarity) and
Desulfobulbus elongatus
(95% sequence similarity) were most frequently found. Different molecular analyses confirmed that
Desulfobulbus
,
Desulfovibrio
, and
Desulfomicrobium
were found to be the numerically important members of SRB in this wastewater biofilm.
Microbial Iron Respiration Can Protect Steel from Corrosion
Authors: Dubiel M. , Hsu C. H. , Chien C. C. , Mansfeld F. , Newman D. K.
Published: July 2002

Microbiologically influenced corrosion (MC) of steel has been attributed to the activity of biofilms that include anaerobic microorganisms such as iron-respiring bacteria, yet the mechanisms by which these organisms influence corrosion have been unclear. To study this process, we generated mutants of the iron-respiring bacterium
Shewanella oneidensis
strain MR-1 that were defective in biofilm formation and/or iron reduction. Electrochemical impedance spectroscopy was used to determine changes in the corrosion rate and corrosion potential as a function of time for these mutants in comparison to the wild type. Counter to prevailing theories of MC, our results indicate that biofilms comprising iron-respiring bacteria may reduce rather than accelerate the corrosion rate of steel. Corrosion inhibition appears to be due to reduction of ferric ions to ferrous ions and increased consumption of oxygen, both of which are direct consequences of microbial respiration.
Bacillus
Probiotics: Spore Germination in the Gastrointestinal Tract
Authors: Casula Gabriella , Cutting Simon M.
Published: July 2002

Spores of
Bacillus
species are being used commercially as probiotics and competitive exclusion agents. Unlike the more commonly used
Lactobacillus
-type probiotics, spores are dormant life forms. To address how spore probiotics might function we have investigated whether spores can germinate in the gastrointestinal tract by using a murine model. Using a genetically engineered chimeric gene,
ftsH-lacZ
, which is strongly expressed only in vegetative cells, we have developed a sensitive competitive reverse transcription-PCR assay which has enabled detection of as few as 10
2
vegetative bacteria in the mouse gut. Using this method we have administered doses of
ftsH-lacZ
spores to groups of mice and shown that spores can germinate in significant numbers in the jejunum and ileum. The levels of detection we obtained suggest that spores may colonize the small intestine, albeit briefly.
Standardized Method of Measuring
Acanthamoeba
Antibodies in Sera from Healthy Human Subjects
Authors: Chappell Cynthia L. , Wright John A. , Coletta Michael , Newsome Anthony L.
Published: July 2002

Acanthamoeba
species can cause serious, debilitating, and sometimes life-threatening infections. Three groups have been identified using morphological and immunological comparisons. Previous serological studies have utilized a variety of antigen preparations and assay methods and reported disparate (3 to 100%) results. This study was designed to (i) optimize an enzyme-linked immunosorbent assay for detecting serum antibodies to each of the
Acanthamoeba
serogroups and (ii) test 55 healthy individuals for specific immunoglobulin G reactivity. The highest signal-to-background ratio was found when 3,000 fixed, intact trophozoites per well were used with a 1:10 serum dilution. Sera yielding optical densities of <0.25 against all three
Acanthamoeba
serogroups were used to define the cutoff for positive results. The highest background reactivity with these sera was seen with
Acanthamoeba polyphaga
(serogroup 2), followed by
Acanthamoeba culbertsoni
(serogroup 3) and
Acanthamoeba astronyxis
(serogroup 1). Of 55 subjects tested, the highest number of positive results was seen with
A. polyphaga
(81.8%), followed by
A. astronyxis
(52.8%) and
A. culbertsoni
(40%). Seven serum samples (12.7%) were negative for all three
Acanthamoeba
serogroups, 16 (29.1%) were positive for one serogroup only, 16 were positive for two serogroups, and 16 reacted to all three serogroups. Further analysis showed no significant associations between serogroup reactivity and age or gender. However, some ethnic differences were noted, especially with
A. polyphaga
antigens. In that case, serum samples from Hispanic subjects were 14.5 times less likely to be positive (
P
= 0.0025) and had lower mean absorbance values (
P
= 0.047) than those from Caucasian subjects. Overall, these data suggest that
Acanthamoeba
colonization or infection is more common than previously thought. Mild or asymptomatic infections may contribute to the observed serum reactivities.
Cystatin Capture Enzyme-Linked Immunosorbent Assay for Serodiagnosis of Human Clonorchiasis and Profile of Captured Antigenic Protein ofClonorchis sinensis
Authors: Kim Tae Yun , Kang Shin-Yong , Park Sun Hyo , Sukontason Kom , Sukontason Kabkaew , Hong Sung-Jong
Published: July 2002

Enzyme-linked immunosorbent assay (ELISA) with crude extracts of adultClonorchis sinensishas been reported to have a high degree of sensitivity with a moderate degree of specificity for the serodiagnosis of clonorchiasis. The cystatin capture ELISA was investigated for its usefulness for the serodiagnosis of human clonorchiasis. Cystatin bound specifically to cysteine proteinases in crude extracts of adultC. sinensisworms, and its binding capacity was not hindered competitively by the other proteinase inhibitors tested. The cystatin capture ELISA for clonorchiasis showed a higher degree of specificity than the conventional ELISA, which produced some cross-reactivities to sera from patients with cysticercosis, sparganosis, and opisthorchiasis. Immunoglobulin G antibodies toC. sinensiscysteine proteinases were produced in experimental rabbits at week 3, and their levels increased rapidly and remained at a plateau after 8 weeks of infection. Of the proteins from theC. sinensiscrude extract captured with cystatin, seven proteins were reactive with the serum from patients with clonorchiasis. The cystatin capture ELISA is indicated to be a sensitive and highly specific immunodiagnostic assay for serodiagnosis of human clonorchiasis.
Contribution of Immune Activation to the Pathogenesis and Transmission of Human Immunodeficiency Virus Type 1 Infection
Authors: Lawn Stephen D. , Butera Salvatore T. , Folks Thomas M.
Published: July 2002

The life cycle of human immunodeficiency virus type 1 (HIV-1) is intricately related to the activation state of the host cells supporting viral replication. Although cellular activation is essential to mount an effective host immune response to invading pathogens, paradoxically the marked systemic immune activation that accompanies HIV-1 infection in vivo may play an important role in sustaining phenomenal rates of HIV-1 replication in infected persons. Moreover, by inducing CD4+cell loss by apoptosis, immune activation may further be central to the increased rate of CD4+cell turnover and eventual development of CD4+lymphocytopenia. In addition to HIV-1-induced immune activation, exogenous immune stimuli such as opportunistic infections may further impact the rate of HIV-1 replication systemically or at localized anatomical sites. Such stimuli may also lead to genotypic and phenotypic changes in the virus pool. Together, these various immunological effects on the biology of HIV-1 may potentially enhance disease progression in HIV-infected persons and may ultimately outweigh the beneficial aspects of antiviral immune responses. This may be particularly important for those living in developing countries, where there is little or no access to antiretroviral drugs and where frequent exposure to pathogenic organisms sustains a chronically heightened state of immune activation. Moreover, immune activation associated with sexually transmitted diseases, chorioamnionitis, and mastitis may have important local effects on HIV-1 replication that may increase the risk of sexual or mother-to-child transmission of HIV-1. The aim of this paper is to provide a broad review of the interrelationship between immune activation and the immunopathogenesis, transmission, progression, and treatment of HIV-1 infection in vivo.
Molecular Cloning and Analysis of a Putative Siderophore ABC Transporter from
Staphylococcus aureus
Authors: Morrissey Julie A. , Cockayne Alan , Hill Philip J. , Williams Paul
Published: July 2002

From a mass-excised
Staphylococcus aureus
λZapII expression library, we cloned an operon encoding a novel ABC transporter with significant homology to bacterial siderophore transporter systems. The operon encodes four genes designated
sstA
, -
B
, -
C
, and -
D
encoding two putative cytoplasmic membrane proteins (
sstA
and
sstB
), an ATPase (
sstC
), and a membrane-bound 38-kDa lipoprotein (
sstD
). The
sst
operon is preceded by two putative Fur boxes, which indicated that expression of the
sst
operon was likely to be iron dependent. SstD was overexpressed in
Escherichia coli
, purified by Triton X-114 phase partitioning, and used to generate monospecific antisera in rats. Immunoblotting studies located SstD in the membrane fraction of
S. aureus
and showed that expression of the lipoprotein was reduced under iron-rich growth conditions. Triton X-114 partitioning studies on isolated membranes provided additional biochemical evidence that SstD in
S. aureus
is a lipoprotein. Immunoreactive polypeptides of approximately 38 kDa were detected in a wide range of staphylococcal species, but no antigenic homolog was detected in
Bacillus subtilis
. Expression of SstD in vivo was confirmed by immunoblotting studies with
S. aureus
recovered from a rat intraperitoneal chamber implant model. To further define the contribution of SstD in promoting growth of
S. aureus
in vitro and in vivo, we used antisense RNA technology to modulate expression of SstD. Expression of antisense
sstD
RNA in
S. aureus
resulted in a decrease in SstD expression under both iron-rich and iron-restricted growth conditions. However, this reduction in SstD levels did not affect the growth of
S. aureus
in vitro in an iron-limited growth medium or when grown in an intraperitoneal rat chamber implant model in vivo.
Inverse Relation between Disease Severity and Expression of the Streptococcal Cysteine Protease, SpeB, among Clonal M1T1 Isolates Recovered from Invasive Group A Streptococcal Infection Cases
Authors: Kansal Rita G. , McGeer Allison , Low Donald E. , Norrby-Teglund Anna , Kotb Malak
Published: July 2002

The streptococcal cysteine protease (SpeB) is one of the major virulence factors produced by group A streptococci (GAS). In this study we investigated if differences exist in SpeB production by clonally related M1T1 clinical isolates derived from patients with invasive infections. Twenty-nine of these isolates were from nonsevere cases and 48 were from severe cases, including streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis (NF) cases. The expression and amount of the 28-kDa SpeB protein produced were determined by quantitative Western blotting, and protease activity was measured by a fluorescent enzymatic assay. A high degree of variation in SpeB expression was seen among the isolates, and this variation seemed to correlate with the severity and/or clinical manifestation of the invasive infection. The mean amount of 28-kDa SpeB protein and cysteine protease activity produced by isolates from nonsevere cases was significantly higher than that from STSS cases (P= 0.001). This difference was partly due to the fact that 41% of STSS isolates produced little or no SpeB compared to only 14% of isolates recovered in nonsevere cases. Moreover, the cysteine protease activity among those isolates that expressed SpeB was significantly lower for STSS isolates than for isolates from nonsevere cases (P= 0.001). Increased SpeB production was also inversely correlated with intact M protein expression, and inhibition of cysteine protease activity blocked the cleavage of the surface M protein. Together, the data support the existence of both an “on-off” and a posttranslational regulatory mechanism(s) controlling SpeB production, and they suggest that isolates with thespeBgene in the “off” state are more likely to spare the surface M protein and to be isolated from cases of severe rather than nonsevere invasive infection. These findings may have important implications for the role of SpeB in host-pathogen interactions via regulation of the expression of GAS virulence genes and the severity of invasive disease.
A Novel Polymorphism in the Toll-Like Receptor 2 Gene and Its Potential Association with Staphylococcal Infection
Authors: Lorenz Eva , Mira Jean Paul , Cornish Kristyn L. , Arbour Nancy C. , Schwartz David A.
Published: July 2002

The toll-like receptor 2 (TLR2) has gained importance as a major mammalian receptor for lipoproteins derived from the cell wall of a variety of bacteria, such asBorrelia burgdorferi,Treponema pallidum, andMycoplasma fermentans. We were interested in identifying mutations in the TLR2 gene that might prove to be associated with altered susceptibility to septic shock. We performed a mutation screen of the TLR2 gene using single-stranded conformational polymorphism in 110 normal, healthy study subjects and detected an Arg753Gln mutation in three individuals. No other missense mutations were detected in the TLR2 open reading frame. Functional studies demonstrate that the Arg753Gln polymorphism, in comparison to the wild-type TLR2 gene, is significantly less responsive to bacterial peptides derived fromB. burgdorferiandT. pallidum. In a septic shock population, the Arg753Gln TLR2 polymorphism occurred in 2 out of 91 septic patients. More importantly, both of the subjects with the TLR2 Arg753Gln polymorphism had staphylococcal infections. These findings suggest that a mutation in the TLR2 gene may predispose individuals to life-threatening bacterial infections.
Transmission Electron Microscopic Demonstration of Phagocytosis and Intracellular Processing of Segmented Filamentous Bacteria by Intestinal Epithelial Cells of the Chick Ileum
Authors: Yamauchi Koh-En , Snel Johannes
Published: July 2002

Segmented filamentous bacteria (SFB) are autochthonous bacteria colonizing the ileum of many young animals by attaching to intestinal epithelial cells. These nonpathogenic bacteria strongly stimulate the mucosal immune system and induce intestinal epithelial cells to express major histocompatibility complex class II molecules. We tried to discover whether SFB are phagocytized and intracellularly processed by the host cells, which is indicative of antigen processing. The middle part of the ileum was extracted from 10- and 20-day-old broiler chicks (
Gallus gallus domesticus
). Samples were processed and examined by scanning and transmission electron microscopy (SEM and TEM, respectively). In SEM, no, few, medium, and dense SFB colonization levels were classified. In TEM of cells from animals with medium or dense SFB colonization levels, we could observe extracellular particles ranging from those only indenting the cell membrane to particles found in the cytoplasmatic area beyond the terminal web. These particles had a structural similarity with SFB that were floating freely in the intestinal lumen. Furthermore, we observed unlacing of the membrane and septum surrounding the extracellular particles and their incorporation into host cytoplasmatic components, which strongly suggests that these particles are phagocytized and intracellularly processed SFB. This conclusion is supported by TEM analysis of samples with no or few SFB, in which we failed to find these characteristic morphologies. The phagocytosis process described here could be an important trigger for the stimulating effect of SFB on the mucosal immune system.
Intercellular Communication in
Helicobacter pylori
:
luxS
Is Essential for the Production of an Extracellular Signaling Molecule
Authors: Forsyth Mark H. , Cover Timothy L.
Published: July 2002

Individual bacteria of numerous species can communicate and coordinate their actions via the production, release, and detection of extracellular signaling molecules. In this study, we used the
Vibrio harveyi
luminescence bioassay to determine whether
Helicobacter pylori
produces such a factor. Cell-free conditioned media from
H. pylori
strains 60190 and 26695 each induced >100-fold-greater luminescence in
V. harveyi
than did sterile culture medium. The
H. pylori
signaling molecule had a molecular mass of <10 kDa, and its activity was unaffected by heating to 80°C for 5 min or protease treatment. The genome sequence of
H. pylori
26695 does not contain any gene predicted to encode an acyl homoserine lactone synthase but does contain an orthologue of
luxS
, which is required for production of autoinducer-2 (AI-2) in
V. harveyi
. To evaluate the role of
luxS
in
H. pylori
, we constructed
luxS
null mutants derived from
H. pylori
60190 and 26695. Conditioned media from the wild-type
H. pylori
strains induced >100-fold-greater luminescence in the
V. harveyi
bioassay than did conditioned medium from either mutant strain. Production of the signaling molecule was restored in an
H. pylori luxS
null mutant strain by complementation with a single intact copy of
luxS
placed in a heterologous site on the chromosome. In addition,
Escherichia coli
DH5α produced autoinducer activity following the introduction of an intact copy of
luxS
from
H. pylori
. Production of the signaling molecule by
H. pylori
was growth phase dependent, with maximal production occurring in the mid-exponential phase of growth. Transcription of
H. pylori vacA
also was growth phase dependent, but this phenomenon was not dependent on
luxS
activity. These data indicate that
H. pylori
produces an extracellular signaling molecule related to AI-2 from
V. harveyi
. We speculate that this signaling molecule may play a role in regulating
H. pylori
gene expression.
Stimulation ofBordetella pertussisAdenylate Cyclase Toxin Intoxication by Its Hemolysin Domain
Authors: Iwaki Masaaki , Kamachi Kazunari , Konda Toshifumi
Published: July 2002

The internalization of the N-terminal catalytic domain ofBordetella pertussisadenylate cyclase toxin (ACT) across the cytoplasmic membrane has been considered to occur independently from protein-protein interactions which can lead to oligomerization required for hemolytic activity by its C-terminal hemolysin domain. Here we report that when added in excess, this hemolysin domain stimulates the internalization, suggesting the involvement of protein-protein interactions in cell-invasive activity of ACT, as well as its hemolytic activity.
Salmonella enterica
Serovar Pullorum Persists in Splenic Macrophages and in the Reproductive Tract during Persistent, Disease-Free Carriage in Chickens
Authors: Wigley P. , Berchieri A. , Page K. L. , Smith A. L. , Barrow P. A.
Published: July 2002

Salmonella enterica
serovar Pullorum is worldwide a poultry pathogen of considerable economic importance, particularly in those countries with a developing poultry industry. In addition to the characteristic high mortality rates among young chicks, one of the features of
Salmonella
serovar Pullorum infection is that it persists for long periods in convalescent chicks in the absence of clinical disease. This can lead to colonization of the reproductive tract of chickens and at sexual maturity can result in infected progeny through transovarian transmission to eggs. The sites of
Salmonella
serovar Pullorum persistence in convalescent birds are not known, and the mechanisms of persistence are not understood. Here we show that
Salmonella
serovar Pullorum can persist in both the spleen and the reproductive tract for over 40 weeks following experimental infection in chickens. During the period of sexual maturity,
Salmonella
serovar Pullorum colonized both the ovary and the oviduct of hens and led to 6% of laid eggs being infected by
Salmonella
serovar Pullorum. The colonization of several different sites of the reproductive tract suggests that
Salmonella
serovar Pullorum may employ more than one mechanism of egg infection. Persistence occurred despite a strong humoral response, suggesting an intracellular site of infection. By use of a
Salmonella
serovar Pullorum strain containing a plasmid stably expressing green fluorescent protein, we demonstrated that the main site of carriage in the spleen is within macrophages. This raises interesting questions about the biology of
Salmonella
serovar Pullorum, including why there is an increase in bacterial numbers when birds become sexually mature and in particular how
Salmonella
serovar Pullorum avoids clearance by macrophages and whether it modulates the immune system in other ways.
Induction of Monocyte Chemoattractant Protein 1 byHelicobacter pyloriInvolves NF-κB
Authors: Mori Naoki , Ueda Atsuhisa , Geleziunas Romas , Wada Akihiro , Hirayama Toshiya , Yoshimura Teizo , Yamamoto Naoki
Published: July 2002

Helicobacter pyloristimulates secretion of monocyte chemoattractant protein 1 (MCP-1) from gastric epithelial cells. Secretion of this chemokine may be instrumental in monocyte infiltration of the gastric epithelium that characterizesH. pylorigastritis. The aim of this study was to identify the mechanism by whichH. pyloriinduces MCP-1 production. Induction of MCP-1 mRNA was assessed by reverse transcription-PCR. We used luciferase reporter assays to monitor activation of the MCP-1 gene promoter and electrophoretic mobility shift assays to explore binding of transcription factors to this promoter.H. pyloriinfection increased MCP-1 mRNA expression from gastric epithelial cells. Induction of MCP-1 mRNA relies on an intactcagpathogenicity island. We identified two closely spaced NF-κB-binding sites within the MCP-1 distal enhancer as required forH. pylori-induced MCP-1 gene transcription.H. pyloriinfection led to the specific activation of NF-κB complexes containing p50 and p65. Kinase-deficient mutants of NF-κB-inducing kinase (NIK) and IκB kinases (IKK) caused suppression of MCP-1 distal enhancer-dependent reporter activity followingH. pyloriinfection.H. pyloriinfection induces the activation of NF-κB via the NIK-IKK signaling complex, leading to MCP-1 gene transcription in gastric epithelial cells.
A Mutation in the
Corynebacterium glutamicum ltsA
Gene Causes Susceptibility to Lysozyme, Temperature-Sensitive Growth, and
l
-Glutamate Production
Authors: Hirasawa Takashi , Wachi Masaaki , Nagai Kazuo
Published: July 2002

The
Corynebacterium glutamicum
mutant KY9714, originally isolated as a lysozyme-sensitive mutant, does not grow at 37°C. Complementation tests and DNA sequencing analysis revealed that a mutation in a single gene of 1,920 bp,
ltsA
(lysozyme and temperature sensitive), was responsible for its lysozyme sensitivity and temperature sensitivity. The
ltsA
gene encodes a protein homologous to the glutamine-dependent asparagine synthetases of various organisms, but it could not rescue the asparagine auxotrophy of an
Escherichia coli asnA asnB
double mutant. Replacement of the N-terminal Cys residue (which is conserved in glutamine-dependent amidotransferases and is essential for enzyme activity) by an Ala residue resulted in the loss of complementation in
C. glutamicum
. The mutant
ltsA
gene has an amber mutation, and the disruption of the
ltsA
gene caused lysozyme and temperature sensitivity similar to that in the KY9714 mutant.
l
-Glutamate production was induced by elevating growth temperature in the disruptant. These results indicate that the
ltsA
gene encodes a novel glutamine-dependent amidotransferase that is involved in the mechanisms of formation of rigid cell wall structure and in the
l
-glutamate production of
C. glutamicum
.