bluuebunny/crossref_metadata_2025 huggingface dataset:
The in vitro cultivation of Hymenolepis microstoma from cysticercoid to egg-producing adult
Authors: Evans W. S.
Published: August 2008

Cysticercoids of Hymenolepis microstoma have been cultured in vitro to egg-producing adults in 16 days using Eagle's medium with horse serum plus sheep or hamster liver extract, and ox bile. Bile was essential for egg production but not for general body growth. Worms became gravid when cultured under 0, 5, and 10% oxygen. However, growth and development was greatly inhibited when higher concentrations of oxygen were used.
DARK MATTER CANDIDATE IN A HEAVY HIGGS MODEL: DIRECT DETECTION RATES
Authors: MAJUMDAR DEBASISH , GHOSAL AMBAR
Published: August 2008

We investigate direct detection rates for Dark Matter candidates arise in a SU (2)L× U (1)Y with an additional doublet Higgs proposed by Barbieri, Hall and Rychkov. We refer to this model as "Heavy Higgs Model". The Standard Model Higgs mass comes out from this model is very heavy, so there is very slim chance that there is no Higgs boson mass below 200 GeV. The additional Higgs boson develops neither any VEV due to the choice of coefficient of the scalar potential of the model nor it has any coupling with fermions due to the incorporation of a discrete parity symmetry. Thus, the neutral components of the extra doublet are stable and can be considered as probable candidate of Cold Dark Matter. We have made calculations for three different types of Dark Matter experiments, namely, 76 Ge (like GENIUS), DAMA (NaI) and XENON (131 Xe ). Also demonstrated the annual variation of Dark Matter detection in case of all three
A NEW DESCRIPTION OF COSMIC STRINGS IN BRANE WORLD SCENARIO
Authors: DUAN YI-SHI , ZHANG LI-DA , LIU YU-XIAO
Published: August 2008

In the light of ϕ-mapping topological current theory, the structure of cosmic strings are obtained from the Abelian Higgs model, which is an effective description to the brane world cosmic string system. In this topological description of the cosmic string, combining the result of decomposition of U(1) gauge potential, we analytically reach the familiar conclusions that in the brane world scenario the magnetic flux of the cosmic string is quantized and the RR charge of it is screened.
GRAVITATIONAL FIELD OF A STRAIGHT COSMIC STRING IN THE FRAMEWORK OF HIGHER-DERIVATIVE GRAVITY
Authors: ACCIOLY ANTONIO , HELAYËL-NETO JOSÉ , LOBO MATHEUS
Published: August 2008

The gravitational properties of a straight cosmic string are studied in the linear approximation of higher-derivative gravity. These properties are shown to be very different from those found using linearized Einstein gravity: there exists a short range gravitational (anti-gravitational) force in the nonrelativistic limit; in addition, the deflection angle of a light ray moving in a plane orthogonal to the string depends on the impact parameter.
HIGH ENERGY COSMIC RAYS, GAMMA RAYS AND NEUTRINOS FROM AGN
Authors: TOMOZAWA YUKIO
Published: August 2008

The author reviews a model for the emission of high energy cosmic rays, gamma-rays and neutrinos from AGN (Active Galactic Nuclei) that he has proposed since 1985. Further discussion of the knee energy phenomenon of the cosmic ray energy spectrum requires the existence of a heavy particle with mass in the knee energy range. A possible method of detecting such a particle in the Pierre Auger Project is suggested. Also presented is a relation between the spectra of neutrinos and gamma-rays emitted from AGN. This relation can be tested by high energy neutrino detectors such as ICECUBE, the Mediterranean Sea Detector and possibly by the Pierre Auger Project.
NEXT-TO-LEADING ORDER QCD CORRECTIONS TO LIGHT HIGGS PAIR PRODUCTION VIA VECTOR BOSON FUSION
Authors: FIGY TERRANCE
Published: August 2008

We present the NLO QCD corrections for light Higgs pair production via vector boson fusion at the LHC within the CP conserving type II two-Higgs doublet model in the form of a fully flexible parton-level Monte Carlo program. Scale dependences on integrated cross sections and distributions are reduced with QCD K-factors of order unity.
CHAOS AND FRACTAL OF THE GENERAL TWO-DIMENSIONAL QUADRATIC MAP
Authors: WANG XINGYUAN
Published: August 2008

The nature of the stable points of the general two-dimensional quadratic map is considered analytically, and the boundary equation of the first bifurcation of the map in the parameter space is given out. The general feature of the nonlinear dynamic activities of the map is analyzed by the method of numerical computation. By utilizing the Lyapunov exponent as a criterion, this paper constructs the strange attractors of the general two-dimensional quadratic map, and calculates the fractal dimension of the strange attractors according to the Lyapunov exponents. At the same time, the researches on the fractal images of the general two-dimensional quadratic map make it clear that when the control parameters are different, the fractal images are different from each other, and these fractal images exhibit the fractal property of self-similarity.
ODD AND EVEN BEHAVIOR WITH LSUBm APPROXIMATION LEVEL IN HIGH-ORDER COUPLED CLUSTER METHOD (CCM) CALCULATIONS
Authors: FARNELL D. J. J. , BISHOP R. F.
Published: August 2008

The coupled cluster method (CCM) is a powerful and widely applied technique of modern-day quantum many-body theory. It has been used with great success in order to understand the properties of quantum magnets at zero temperature. This is largely due to the application of computational techniques that allow the method to be applied to high orders of approximation using a localized scheme known as the LSUBm scheme. A hitherto unreported aspect of this scheme is that results for LSUBm expectation values behave in distinctly different ways with odd and even values of m. Here, we consider the behavior of ground-state expectation values of odd and even orders of the CCM LSUBm approximation for unfrustrated spin-half Heisenberg antiferromagnets on the square and honeycomb lattice and the frustrated spin-half Heisenberg antiferromagnet on the triangular lattice. We demonstrate that results for odd and even orders of approximation show qualitatively different behavior for both the ground-state energy and the sublattice magnetization. Indeed, the odd series consistently forms an upper branch of results, and the even series a lower branch with respect to both ground-state energy and sublattice magnetization, for all of the models considered here.
GLOBAL FLUCTUATIONS IN PHYSICAL SYSTEMS: A SUBTLE INTERPLAY BETWEEN SUM AND EXTREME VALUE STATISTICS
Authors: CLUSEL MAXIME , BERTIN ERIC
Published: August 2008

Fluctuations of global additive quantities, like total energy or magnetization for instance, can in principle be described by statistics of sums of (possibly correlated) random variables. Yet, it turns out that extreme values (the largest value among a set of random variables) may also play a role in the statistics of global quantities, in a direct or indirect way. This review discusses different connections that may appear between problems of sums and of extreme values of random variables, and emphasizes physical situations in which such connections are relevant. Along this line of thought, standard convergence theorems for sums and extreme values of independent and identically distributed random variables are recalled, and some rigorous results as well as more heuristic reasonings are presented for correlated or non-identically distributed random variables. More specifically, the role of extreme values within sums of broadly distributed variables is addressed, and a general mapping between extreme values and sums is presented, allowing us to identify a class of correlated random variables whose sum follows (generalized) extreme value distributions. Possible applications of this specific class of random variables are illustrated on the example of two simple physical models. A few extensions to other related classes of random variables sharing similar qualitative properties are also briefly discussed, in connection with the so-called BHP distribution.
PHONON EXCESS HEATING IN ELECTRONIC RELAXATION THEORY IN QUANTUM DOTS
Authors: KRÁL KAREL , LIN CHUNG-YI
Published: August 2008

When the usual operator of the Fröhlich's coupling between electrons and longitudinal optical phonons of semiconductor single quantum dot is used to calculate electronic energy relaxation, a permanent phonon generation in quantum dot is obtained, leading to an artificial effect of permanent heating up of the lattice. The mechanism of the phonon heating is identified here with the influence of the transverse part of the interaction operator. This part is responsible first of all for a tendency to build the polaronic well of an electron in a quantum dot. The effect of overheating is shown to be possibly eliminated to a considerable extent upon removing the transverse part of the interaction with the help of the Lang–Firsov canonical transformation and upon modifying accordingly the longitudinal part of the coupling. The resulting electronic relaxation and optical phonon generation is demonstrated numerically in a relatively simple approximation to electron and phonon self-energy, in which the model of quantum dot is reduced to an electron coupled to a single-LO-phonon mode. It is interesting to see that the removal of the phonon overheating based on the application of the Lang–Firsov canonical transformation has a rather small influence on electronic characteristics calculated with electronic transport equations. In this sense, the long-time limit properties of the electronic subsystem, like the electronic up-conversion and incomplete depopulation effect, calculated earlier, remain nearly untouched.
Ispy
Authors: Zhang Zheng , Zhang Ying , Hu Y. Charlie , Mao Z. Morley , Bush Randy
Published: August 2008

IP prefix hijacking remains a major threat to the security of the Internet routing system due to a lack of authoritative prefix ownership information. Despite many efforts in designing IP prefix hijack detection schemes, no existing design can satisfy all the critical requirements of a truly effective system: real-time, accurate, light-weight, easily and incrementally deployable, as well as robust in victim notification. In this paper, we present a novel approach that fulfills all these goals by monitoring network reachability from key external transit networks to one's own network through lightweight prefix-owner-based active probing. Using the prefix-owner's view of reachability, our detection system, iSPY, can differentiate between IP prefix hijacking and network failures based on the observation that hijacking is likely to result in topologically more diverse polluted networks and unreachability. Through detailed simulations of Internet routing, 25-day deployment in 88 ASes (108 prefixes), and experiments with hijacking events of our own prefix from multiple locations, we demonstrate that iSPY is accurate with false negative ratio below 0.45% and false positive ratio below 0.17%. Furthermore, iSPY is truly real-time; it can detect hijacking events within a few minutes.
Evolution of Debris Disks
Authors: Wyatt Mark C.
Published: August 2008

Circumstellar dust exists around several hundred main sequence stars. For the youngest stars, that dust could be a remnant of the protoplanetary disk. Mostly it is inferred to be continuously replenished through collisions between planetesimals in belts analogous to the Solar System's asteroid and Kuiper belts, or in collisions between growing protoplanets. The evolution of a star's debris disk is indicative of the evolution of its planetesimal belts and may be influenced by planet formation processes, which can continue throughout the first gigayear as the planetary system settles to a stable configuration and planets form at large radii. Evidence for that evolution comes from infrared photometry of large numbers of debris disks, providing snapshots of the dust present at different evolutionary phases, as well as from images of debris disk structure. This review describes the theoretical framework within which debris disk evolution takes place and shows how that framework has been constrained by observations.
Interstellar Polycyclic Aromatic Hydrocarbon Molecules
Authors: Tielens A.G.G.M.
Published: August 2008

Large polycyclic aromatic hydrocarbon (PAH) molecules carry the infrared (IR) emission features that dominate the spectra of most galactic and extragalactic sources. This review surveys the observed mid-IR characteristics of these emission features and summarizes laboratory and theoretical studies of the spectral characteristics of PAHs and the derived intrinsic properties of emitting interstellar PAHs. Dedicated experimental studies have provided critical input for detailed astronomical models that probe the origin and evolution of interstellar PAHs and their role in the universe. The physics and chemistry of PAHs are discussed, emphasizing the contribution of these species to the photoelectric heating and the ionization balance of the interstellar gas and to the formation of small hydrocarbon radicals and carbon chains. Together, these studies demonstrate that PAHs are abundant, ubiquitous, and a dominant force in the interstellar medium of galaxies.
Endocannabinoids and Liver Disease. V. Endocannabinoids as mediators of vascular and cardiac abnormalities in cirrhosis
Authors: Moezi Leila , Gaskari Seyed Ali , Lee Samuel S.
Published: August 2008

Cirrhosis is associated with marked cardiovascular disturbances. These include hyperdynamic circulation characterized by reduced peripheral vascular resistance and mean arterial pressure and increased cardiac output. Despite the baseline increase in cardiac output, ventricular responsiveness to stimuli is blunted. A number of cellular signaling pathways have been shown to contribute to these abnormalities, including central nervous system cardiovascular dysregulation and humoral factors such as nitric oxide. Endogenous and exogenous cannabinoids have significant cardiovascular effects. Recent evidence suggests that increased activity of the endocannabinoid system at multiple levels contributes to development of both cardiac and vascular changes in cirrhosis. This brief review surveys recent in vivo and in vitro findings in an attempt to highlight the areas of agreement and areas of controversy in the field. The endocannabinoid system affects key cardiovascular regulators, including the autonomic nervous system, cardiac muscle, and vascular smooth muscle. The interplay among these modes of action further complicates interpretation of the in vivo findings. The broad range of cardiovascular actions of endocannabinoids provides ample opportunities for pharmacological manipulation. At the same time, it increases the possibility of undesirable side effects, which need to be carefully evaluated in long-term studies.
Coenzyme Q1redox metabolism during passage through the rat pulmonary circulation and the effect of hyperoxia
Authors: Audi Said H. , Merker Marilyn P. , Krenz Gary S. , Ahuja Taniya , Roerig David L. , Bongard Robert D.
Published: August 2008

The objective was to evaluate the pulmonary disposition of the ubiquinone homolog coenzyme Q1(CoQ1) on passage through lungs of normoxic (exposed to room air) and hyperoxic (exposed to 85% O2for 48 h) rats. CoQ1or its hydroquinone (CoQ1H2) was infused into the arterial inflow of isolated, perfused lungs, and the venous efflux rates of CoQ1H2and CoQ1were measured. CoQ1H2appeared in the venous effluent when CoQ1was infused, and CoQ1appeared when CoQ1H2was infused. In normoxic lungs, CoQ1H2efflux rates when CoQ1was infused decreased by 58 and 33% in the presence of rotenone (mitochondrial complex I inhibitor) and dicumarol [NAD(P)H-quinone oxidoreductase 1 (NQO1) inhibitor], respectively. Inhibitor studies also revealed that lung CoQ1H2oxidation was via mitochondrial complex III. In hyperoxic lungs, CoQ1H2efflux rates when CoQ1was infused decreased by 23% compared with normoxic lungs. Based on inhibitor effects and a kinetic model, the effect of hyperoxia could be attributed predominantly to 47% decrease in the capacity of complex I-mediated CoQ1reduction, with no change in the other redox processes. Complex I activity in lung homogenates was also lower for hyperoxic than for normoxic lungs. These studies reveal that lung complexes I and III and NQO1 play a dominant role in determining the vascular concentration and redox status of CoQ1during passage through the pulmonary circulation, and that exposure to hyperoxia decreases the overall capacity of the lung to reduce CoQ1to CoQ1H2due to a depression in complex I activity.
Cardiovascular changes of conscious rats after simulated microgravity with and without daily −Gxgravitation
Authors: Zhang Li-Fan , Cheng Jiu-Hua , Liu Xin , Wang Shouyan , Liu Yang , Lu Hong-Bing , Ma Jin
Published: August 2008

This study was designed to test the hypothesis that postsuspension cardiovascular manifestation in conscious rats after a medium-term (28-day) tail suspension (SUS) is hypertensive and tachycardiac and can be prevented by a countermeasure of daily 1-h dorsoventral (−Gx) gravitation provided by standing (STD). To assess associated changes in cardiovascular regulation, blood pressure (BP) and heart rate (HR) variability were analyzed by spectral analysis computed by parametric autoregressive (AR) method and by nonlinear recurrence quantification analysis (RQA) and approximate entropy (ApEn) measure. The results showed that conscious SUS rats manifested hypertensive and tachycardiac response before and after being released from suspension compared with the controls, and the countermeasure of 1 h/day −Gxprevented the hypertensive response. Auto- and cross-spectral analysis and transfer function analysis did not show significant changes in cardiovascular variability. However, SUS decreased the three RQA indexes [recurrence percentage (RC%), determinism percentage (DT%), and the longest diagonal line ( Lmax)] of systolic BP, whereas STD alleviated these changes. ApEn values of HR data sets were significantly higher in the SUS and SUS + STD groups compared with those of the control group before and after release from suspension. The present study has demonstrated that daily −Gxfor as short as 1 h is sufficient to prevent postsuspension cardiovascular alteration in conscious rats after a medium-term SUS. Nonlinear measures, but not spectral analysis, might provide promising data to estimate the overall changes in cardiovascular autonomic regulation due to microgravity exposure.
Effect of eccentric exercise-induced muscle damage on the dynamics of muscle oxygenation and pulmonary oxygen uptake
Authors: Davies Rosemary C. , Eston Roger G. , Poole David C. , Rowlands Ann V. , DiMenna Fred , Wilkerson Daryl P. , Twist Craig , Jones Andrew M.
Published: August 2008

Unaccustomed eccentric exercise has a profound impact on muscle structure and function. However, it is not known whether associated microvascular dysfunction disrupts the matching of O2delivery (Q̇o2) to O2utilization (V̇o2). Near-infrared spectroscopy (NIRS) was used to test the hypothesis that eccentric exercise-induced muscle damage would elevate the muscle Q̇o2:V̇o2ratio during severe-intensity exercise while preserving the speed of the V̇o2kinetics at exercise onset. Nine physically active men completed “step” tests to severe-intensity exercise from an unloaded baseline on a cycle ergometer before (Pre) and 48 h after (Post) eccentric exercise (100 squats with a load corresponding to 70% of body mass). NIRS and breath-by-breath pulmonary V̇o2were measured continuously during the exercise tests and subsequently modeled using standard nonlinear regression techniques. There were no changes in phase II pulmonary V̇o2kinetics following the onset of exercise (time constant: Pre, 25 ± 4 s; Post, 24 ± 2 s; amplitude: Pre, 2.36 ± 0.23 l/min; Post, 2.37 ± 0.23 l/min; all P > 0.05). However, the primary (Pre, 14 ± 3 s; Post, 19 ± 3 s) and overall (Pre, 16 ± 4 s; Post, 21 ± 4 s) mean response time of the [HHb] response was significantly slower following eccentric exercise ( P < 0.05). The slower [HHb] kinetics observed following eccentric exercise is consistent with an increased Q̇o2:V̇o2ratio during transitions to severe-intensity exercise. We propose that unchanged primary phase V̇o2kinetics are associated with an elevated Q̇o2:V̇o2ratio that preserves blood-myocyte O2flux.
The Relative Contribution of Point Mutations and Genomic Rearrangements in BRCA1 and BRCA2 in High-Risk Breast Cancer Families
Authors: Palma Maurizia Dalla , Domchek Susan M. , Stopfer Jill , Erlichman Julie , Siegfried Jill D. , Tigges-Cardwell Jessica , Mason Bernard A. , Rebbeck Timothy R. , Nathanson Katherine L.
Published: August 2008

The demand for BRCA1 and BRCA2 mutation screening is increasing as their identification will affect medical management. However, both the contribution of different mutation types in BRCA1 and BRCA2 and whom should be offered testing for large genomic rearrangements have not been well established in the U.S. high-risk population. We define the prevalence and spectrum of point mutations and genomic rearrangements in BRCA genes in a large U.S. high-risk clinic population of both non-Ashkenazi and Ashkenazi Jewish descent, using a sample set representative of the U.S. genetic testing population. Two hundred fifty-one probands ascertained through the University of Pennsylvania high-risk clinic, all with commercial testing for BRCA1 and BRCA2, with an estimated prevalence of BRCA mutation ≥10% using the Myriad II model and a DNA sample available, were studied. Individuals without deleterious point mutations were screened for genomic rearrangements in BRCA1 and BRCA2. In the 136 non-Ashkenazi Jewish probands, 36 (26%) BRCA point mutations and 8 (6%) genomic rearrangements (7 in BRCA1 and 1 in BRCA2) were identified. Forty-seven of the 115 (40%) Ashkenazi Jewish probands had point mutations; no genomic rearrangements were identified in the group without mutations. In the non-Ashkenazi Jewish probands, genomic rearrangements constituted 18% of all identified BRCA mutations; estimated mutation prevalence (Myriad II model) was not predictive of their presence. Whereas these findings should be confirmed in larger sample sets, our data suggest that genomic rearrangement testing be considered in all non-Ashkenazi Jewish women with an estimated mutation prevalence ≥10%. [Cancer Res 2008;68(17):7006–14]
Effect of Language on Colorectal Cancer Screening Among Latinos and Non-Latinos
Authors: Diaz Joseph A. , Roberts Mary B. , Goldman Roberta E. , Weitzen Sherrie , Eaton Charles B.
Published: August 2008

Background: Language barriers among some Latinos may contribute to the lower rates of colorectal cancer (CRC) screening between Latinos and non-Latino Whites. The purpose of this study was to examine the relationship between language and receipt of CRC screening tests among Latinos and non-Latinos using a geographically diverse, population-based sample of adults.

Methods: Cross-sectional analysis of the Behavioral Risk Factor Surveillance System (BRFSS) survey. Analysis included adults age 50 years and older, who completed the 2006 BRFSS in a state that recorded data from English- and Spanish-speaking participants.

Results: The primary outcome measure was receipt of colorectal screening tests (fecal occult blood testing within prior 12 months and/or lower endoscopy within 10 years). Of the 99,895 respondents included in the study populations, 33% of Latinos responding-in-Spanish reported having had CRC testing, whereas 51% of Latinos responding-in-English and 62% of English-speaking non-Latinos reported test receipt. In multivariable analysis, compared with non-Latinos, Latinos responding-in-English were 16% less likely to have received CRC testing [odds ratio (OR), 0.84; 95% confidence interval (95% CI), 0.73-0.98], and Latinos responding-in-Spanish were 43% less likely to have received CRC testing (OR, 0.57; 95% CI, 0.44-0.74). Additionally, compared with Latinos responding-in-English, Latinos responding-in-Spanish were 36% less likely to have received CRC testing (OR, 0.64; 95% CI, 0.48-0.84).

Conclusion: Latinos responding to the 2006 BRFSS survey in Spanish had a significantly lower likelihood of receiving CRC screening tests compared with non-Latinos and to Latinos responding-in-English. Based on this analysis, Spanish language use is negatively associated with CRC screening and may contribute to disparities in CRC screening. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2169–73)
Variants of DNA Repair Genes and the Risk of Biliary Tract Cancers and Stones: A Population-Based Study in China
Authors: Zhang Mingdong , Huang Wen-Yi , Andreotti Gabriella , Gao Yu-Tang , Rashid Asif , Chen Jinbo , Sakoda Lori C. , Shen Ming-Chang , Wang Bing-Sheng , Chanock Stephen , Hsing Ann W.
Published: August 2008

Biliary tract cancers, which encompass tumors of the gallbladder, extrahepatic ducts, and ampulla of Vater, are relatively rare tumors with a high fatality rate. Other than a close link with gallstones, the etiology of biliary tract cancers is poorly understood. We conducted a population-based case-control study in Shanghai, China, to examine whether genetic variants in several DNA repair genes are associated with biliary tract cancers or biliary stones. Genomic DNA from 410 patients with biliary tract cancers (236 gallbladder, 127 bile duct, and 47 ampulla of Vater), 891 patients with biliary stones, and 786 healthy subjects randomly selected from the Shanghai population were genotyped for putative functional single nucleotide polymorphisms in four DNA repair genes (MGMT, RAD23B, CCNH, and XRCC3). Of the five single nucleotide polymorphisms examined, only one (MGMT EX5-25C>T, rs12917) was associated with biliary tract cancer. Independent of gallstones, subjects carrying the CT genotype of the MGMT EX5-25C>T marker had a significantly reduced risk of gallbladder cancer [odds ratio (OR), 0.63; 95% confidence interval (95% CI), 0.41-0.97; P = 0.02] and nonsignificant reduced risks of bile duct (OR, 0.61; 95% CI, 0.35-1.06) and ampulla of Vater (OR, 0.85; 95% CI, 0.39-1.87) cancers. However, this marker was not associated with biliary stones, and the other markers examined were not significantly associated with either biliary tract cancers or stones. Findings from this population-based study in Shanghai suggest that MGMT gene variants may alter susceptibility to biliary tract cancer, particularly gallbladder cancer. Confirmation in future studies, however, is required. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2123–7)
Assessment of Serum Proteomics to Detect Large Colon Adenomas
Authors: Ransohoff David F. , Martin Christopher , Wiggins Wesley S. , Hitt Ben A. , Keku Temitope O. , Galanko Joseph A. , Sandler Robert S.
Published: August 2008

A noninvasive blood test that could reliably detect early colorectal cancer or large adenomas would provide an important advance in colon cancer screening. The purpose of this study was to determine whether a serum proteomics assay could discriminate between persons with and without a large (≥1 cm) colon adenoma. To avoid problems of “bias” that have affected many studies about molecular markers for diagnosis, specimens were obtained from a previously conducted study of colorectal cancer etiology in which bloods had been collected before the presence or absence of neoplasm had been determined by colonoscopy, helping to assure that biases related to differences in sample collection and handling would be avoided. Mass spectra of 65 unblinded serum samples were acquired using a nanoelectrospray ionization source on a QSTAR-XL mass spectrometer. Classification patterns were developed using the ProteomeQuest® algorithm, performing measurements twice on each specimen, and then applied to a blinded validation set of 70 specimens. After removing 33 specimens that had discordant results, the “test group” comprised 37 specimens that had never been used in training. Although in the primary analysis, no discrimination was found, a single post hoc analysis, done after hemolyzed specimens had been removed, showed a sensitivity of 78%, a specificity of 53%, and an accuracy of 63% (95% confidence interval, 53-72%). The results of this study, although preliminary, suggest that further study of serum proteomics, in a larger number of appropriate specimens, could be useful. They also highlight the importance of understanding sources of “noise” and “bias” in studies of proteomics assays. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2188–93)
Social-Cognitive and School Factors in Lifetime Smoking among Adolescents
Authors: Bidstrup Pernille Envold , Frederiksen Kirsten , Siersma Volkert , Mortensen Erik Lykke , Ross Lone , Vinther-Larsen Mathilde , Grønbæk Morten , Johansen Christoffer
Published: August 2008

Background: Smoking is a serious health threat and identifying risk factors for smoking is thus of great importance. The aim of the study was to examine the effects of social-cognitive factors and school factors on lifetime smoking status among adolescents.

Methods: The study was based on cross-sectional data on 2,913 Danish adolescents in grade 7 attending 118 randomly selected public schools. Social-cognitive factors were examined with five measures: self-efficacy to resist pressure to smoke, social influence (norms), social influence (behavior), social influence (pressure), and attitude. We used multilevel analyses to estimate the associations between social-cognitive factors and lifetime smoking status as well as the group-level effects of school, school class, and gender group in the school class.

Results: Each social-cognitive factor was significantly associated with lifetime smoking status, even when several potential confounders and the effects of school, school class, and gender group were taken into account. Of the three group-level school factors, gender group in the school class had the strongest effect on smoking status.

Conclusion: We conclude that self-efficacy to resist pressure to smoke, attitude, and the three types of social influence are significantly associated with lifetime smoking status, even when the effects of group-level school factors are taken into account. The strong effect of gender group in school class on lifetime smoking status indicates that prevention actions should address the social context of adolescents. (Cancer Epidemiol Biomarkers Prev 2008;17(8):1862–71)
Association of Mitochondrial DNA Displacement Loop (CA)n Dinucleotide Repeat Polymorphism with Breast Cancer Risk and Survival among Chinese Women
Authors: Ye Chuanzhong , Gao Yu-Tang , Wen Wanqing , Breyer Joan P. , Shu Xiao Ou , Smith Jeffrey R. , Zheng Wei , Cai Qiuyin
Published: August 2008

Mitochondrial genome alternations may be involved in carcinogenesis. The noncoding region of the mitochondrial DNA (mtDNA) displacement loop (D-loop) has emerged as a mutational hotspot. Using data from a population-based case-control study conducted among Chinese women in Shanghai, we evaluated associations of breast cancer risk and survival with the mtDNA D-loop (CA)n dinucleotide repeat polymorphism. Included in the study were 1,058 cases and 1,129 age frequency–matched community controls that participated in the Shanghai Breast Cancer Study between 1996 and 1998. Breast cancer patients were followed to determine intervals of overall survival and disease-free survival. Overall, there was no association between the mtDNA D-loop (CA)n repeat polymorphism and breast cancer risk. Patients with multiple alleles of the mtDNA D-loop (CA)n polymorphism (heteroplasmy) had significantly poorer disease-free survival than those with one allele of the mtDNA D-loop (CA)n polymorphism (hazard ratio 1.62; 95% confidence interval, 1.16-2.26). These results suggest that the mtDNA D-loop (CA)n repeat polymorphism may be associated with breast cancer survival. Additional studies with a larger sample size are warranted. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2117–22)
Vitamins B2, B6, and B12 and Risk of New Colorectal Adenomas in a Randomized Trial of Aspirin Use and Folic Acid Supplementation
Authors: Figueiredo Jane C. , Levine A. Joan , Grau Maria V. , Midttun Øivind , Ueland Per M. , Ahnen Dennis J. , Barry Elizabeth L. , Tsang Shirley , Munroe David , Ali Iqbal , Haile Robert W. , Sandler Robert S. , Baron John A.
Published: August 2008

Background: Folate, other vitamin B cofactors, and genes involved in folate-mediated one-carbon metabolism all may play important roles in colorectal neoplasia. In this study, we examined the associations between dietary and circulating plasma levels of vitamins B2, B6, and B12 and risk colorectal adenomas.

Methods: The Aspirin/Folate Polyp Prevention Study is a randomized clinical trial of folic acid supplementation and incidence of new colorectal adenomas in individuals with a history of adenomas (n = 1,084). Diet and supplement use were ascertained through a food frequency questionnaire administered at baseline. Blood collected at baseline was used to determine plasma B-vitamin levels. We used generalized linear regression to estimate risk ratios (RR) and 95% confidence intervals (95% CI) as measures of association.

Results: We found a borderline significant inverse association with plasma B6 [pyridoxal 5′-phosphate (PLP)] and adenoma risk (adjusted RR Q4 versus Q1, 0.78; 95% CI, 0.61-1.00; Ptrend = 0.08). This association was not modified by folic acid supplementation or plasma folate. However, the protective association of PLP with adenoma risk was observed only among subjects who did not drink alcohol (Pinteraction = 0.03). Plasma B2 (riboflavin) was inversely associated with risk of advanced lesions (adjusted RR Q4 versus Q1, 0.51; 95% CI, 0.26-0.99; Ptrend = 0.12). No significant associations were observed between adenoma risk and plasma vitamin B12 or dietary intake of vitamin B2 and B6. When we examined specific gene-B-vitamin interactions, we observed a possible interaction between methylenetetrahydrofolate reductase -C677T and plasma B2 on risk of all adenomas.

Conclusion: Our results suggest that high levels of PLP and B2 may protect against colorectal adenomas. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2136–45)
Effect of Prediagnostic Alcohol Consumption on Survival after Breast Cancer in Young Women
Authors: Reding Kerryn W. , Daling Janet R. , Doody David R. , O'Brien Cecilia A. , Porter Peggy L. , Malone Kathleen E.
Published: August 2008

Background: Alcohol consumption has been comprehensively investigated as an etiologic risk factor for breast cancer but has received little attention in terms of its effect on prognosis after breast cancer, particularly for young women.

Methods: 1,286 women diagnosed with invasive breast cancer at age ≤45 years from two population-based case-control studies in the Seattle-Puget Sound region were followed from their diagnosis of breast cancer (between January 1983 and December 1992) for survival through June 2002, during which time 364 women had died. Cox proportional hazards modeling was used to assess the effect of prediagnostic alcohol consumption on the risk of dying.

Results: After adjusting for age and diagnosis year, compared with nondrinkers, women who consumed alcohol in the 5 years before diagnosis had a decreased risk of death [>0 to <3 drinks per week: hazard ratio, 0.7; 95% confidence interval (95% CI), 0.6-0.95; 3 to <7 drinks per week: risk ratio, 0.6; 95% CI, 0.4-0.8;7 drinks per week: risk ratio, 0.7; 95% CI, 0.5-0.9]. This association was unchanged on additional adjustment for potential confounders including most notably treatment, stage at diagnosis, and mammogram history.

Conclusion: These results suggest that women who consume alcohol before a diagnosis of breast cancer have improved survival, which does not appear to be attributable to differences in stage, screening, or treatment. (Cancer Epidemiol Biomarkers Prev 2008;17(8):1988–96)
B-Vitamin Intake, One-Carbon Metabolism, and Survival in a Population-Based Study of Women with Breast Cancer
Authors: Xu Xinran , Gammon Marilie D. , Wetmur James G. , Bradshaw Patrick T. , Teitelbaum Susan L. , Neugut Alfred I. , Santella Regina M. , Chen Jia
Published: August 2008

Breast cancer is the second leading cause of cancer mortality among women. Given its important role in DNA methylation and synthesis, one-carbon metabolism may affect breast cancer mortality. We used a population-based cohort of 1,508 women with breast cancer to investigate possible associations of dietary intake of B vitamins before diagnosis as well as nine polymorphisms of one-carbon metabolizing genes and subsequent survival. Women newly diagnosed with a first primary breast cancer in 1996 to 1997 were followed for vital status for an average of 5.6 years. Kaplan-Meier survival and Cox proportional hazard regression analyses were used to evaluate the association between dietary intakes of B vitamins (1,479 cases), genotypes (∼1,065 cases), and all-cause as well as breast cancer–specific mortality. We found that higher dietary intake of vitamin B1 and B3 was associated with improved survival during the follow-up period (Ptrend = 0.01 and 0.04, respectively). Compared with the major genotype, the MTHFR 677 T allele carriers have reduced all-cause mortality and breast cancer–specific mortality in a dominant model [hazard ratio (95% confidence interval): 0.69 (0.49-0.98) and 0.58 (0.38-0.89), respectively]. The BHMT 742 A allele was also associated with reduced all-cause mortality [hazard ratio, 0.70 (0.50-1.00)]. Estrogen receptor/progesterone receptor status modified the association between the MTHFR C677T polymorphism and survival (P = 0.05). The survival associations with one-carbon polymorphisms did not differ with the use of chemotherapy, although study power was limited for examining such effect modification. Our results indicate that one-carbon metabolism may be an important pathway that could be targeted to improve breast cancer survival. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2109–16)
Mechanisms and Consequences of Chromosomal Translocation
Authors: Rabkin Charles S. , Janz Siegfried
Published: August 2008

A 2006 National Cancer Institute workshop on chromosomal translocations brought together laboratory, clinical, and population scientists to cross-fertilize and catalyze research on this important disease process. The deliberations revealed significant contrasts between two types of translocations that result in either deregulated expression of oncogenes or formation of novel fusion genes. The classic oncogene-activating translocation, MYC-IGH, has been elucidated in terms of molecular structure and functional consequences yet has little epidemiologic characterization. In comparison, the archetypal fusion-gene translocation, BCR-ABL, has well-described clinical manifestations but is less defined with regard to mechanism of generation. Interdisciplinary collaboration on chromosomal translocations should yield additional insights regarding their biological significance and potential as targets for intervention. (Cancer Epidemiol Biomarkers Prev 2008;17(8):1849–51)
Self-Sampling for Human Papillomavirus in a Community Setting: Feasibility in Hispanic Women
Authors: De Alba Israel , Anton-Culver Hoda , Hubbell F. Allan , Ziogas Argyrios , Hess James R. , Bracho America , Arias Caleb , Manetta Alberto
Published: August 2008

Background: The aim of the study was (a) to assess sensitivity and specificity of self-sampling in a community setting for identifying high-risk human papillomavirus (HPV) infection and abnormal Papanicolaou (Pap) smears and (b) to assess satisfaction with this collection method among Hispanic women.

Methods: Lay health workers distributed self-collection kits to Hispanic women in the community. Participants collected an unsupervised vaginal sample at home or in the place and time of their preference.

Results: A total of 1,213 Hispanics were included and provided a self-sample for HPV testing and were invited for a Pap smear; 662 (55%) of them had a Pap smear and the first 386 of these also had a physician-collected sample for HPV retesting. Using physician collection as the gold standard, unsupervised self-collection had a sensitivity of 90% and specificity of 88% for identifying high-risk HPV. Compared with physician sampling, self-sampling in a community setting had comparable sensitivity for identifying a low-grade lesions or greater in the Pap smear (50% versus 55%; P = 0.45) but lower specificity (94% versus 79%). Overall experience with self-sampling was reported as excellent or very good by 64% and only 2.6% reported a poor or fair experience.

Conclusions: Unsupervised self-collection of vaginal samples for HPV testing in a community setting has a high sensitivity for identifying high-risk HPV and a high satisfaction among Hispanics. This approach may benefit populations with limited access to health care or with cultural barriers to cervical cancer screening. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2163–8)
Involuntary Smoking and Head and Neck Cancer Risk: Pooled Analysis in the International Head and Neck Cancer Epidemiology Consortium
Authors: Lee Yuan-Chin Amy , Boffetta Paolo , Sturgis Erich M. , Wei Qingyi , Zhang Zuo-Feng , Muscat Joshua , Lazarus Philip , Matos Elena , Hayes Richard B. , Winn Deborah M. , Zaridze David , Wünsch-Filho Victor , Eluf-Neto Jose , Koifman Sergio , Mates Dana , Curado Maria Paula , Menezes Ana , Fernandez Leticia , Daudt Alexander W. , Szeszenia-Dabrowska Neonila , Fabianova Eleonora , Rudnai Peter , Ferro Gilles , Berthiller Julien , Brennan Paul , Hashibe Mia
Published: August 2008

Although active tobacco smoking has been identified as a major risk factor for head and neck cancer, involuntary smoking has not been adequately evaluated because of the relatively low statistical power in previous studies. We took advantage of data pooled in the International Head and Neck Cancer Epidemiology Consortium to evaluate the role of involuntary smoking in head and neck carcinogenesis. Involuntary smoking exposure data were pooled across six case-control studies in Central Europe, Latin America, and the United States. Adjusted odds ratios (OR) and 95% confidence interval (95% CI) were estimated for 542 cases and 2,197 controls who reported never using tobacco, and the heterogeneity among the study-specific ORs was assessed. In addition, stratified analyses were done by subsite. No effect of ever involuntary smoking exposure either at home or at work was observed for head and neck cancer overall. However, long duration of involuntary smoking exposure at home and at work was associated with an increased risk (OR for >15 years at home, 1.60; 95% CI, 1.12-2.28; Ptrend < 0.01; OR for >15 years at work, 1.55; 95% CI, 1.04-2.30; Ptrend = 0.13). The effect of duration of involuntary smoking exposure at home was stronger for pharyngeal and laryngeal cancers than for other subsites. An association between involuntary smoking exposure and the risk of head and neck cancer, particularly pharyngeal and laryngeal cancers, was observed for long duration of exposure. These results are consistent with those for active smoking and suggest that elimination of involuntary smoking exposure might reduce head and neck cancer risk among never smokers. (Cancer Epidemiol Biomarkers Prev 2008;17(8):1974–81)
Does Pretreatment Seropositivity to Human Papillomavirus Have Prognostic Significance for Head and Neck Cancers?
Authors: Smith Elaine M. , Rubenstein Linda M. , Ritchie Justine M. , Lee John H. , Haugen Thomas H. , Hamsikova Eva , Turek Lubomir P.
Published: August 2008

Background: Human papillomavirus (HPV) is a risk factor for head and neck cancers (HNC), yet HPV-associated tumors have better prognosis than HPV-negative tumors.

Methods: We evaluated whether pretreatment presence of antibodies to HPV capsids [virus-like particles (VLP)] or to HPV-16 oncoproteins E6 and E7 was a predictor of HPV-positive HNC and clinical outcomes. Sera from 156 HNC patients were tested for antibodies to HPV-16–derived antigens using ELISA. HPV-16 in tumors was evaluated by PCR and DNA sequencing.

Results: HPV-16 antibodies were found in 33% with HPV-16 VLP, 21% with HPV-16 E6, and 21% with E7. HPV-16 was detected in 26% of tumors. There was a strong correlation between detection of HPV-16 tumor DNA and antibodies to HPV-16 E6 or E7 (κ = 0.7) but not to HPV-16 VLP (κ = 0.4). Multivariate analyses showed significantly better disease-specific survival in seropositive HPV-16 VLP [hazard ratio (HR), 0.4; 95% confidence interval (95% CI), 0.1-0.9], HPV-16 E6 (HR, 0.1; 95% CI, 0.02-0.5), and HPV-16 E7 (HR, 0.3; 95% CI, 0.1-0.9) cases. Less disease recurrence occurred among those with antibodies to both E6 and E7 compared with those negative to both (P = 0.003). There was better disease-specific survival in patients who were E6 positive at baseline and remained positive at follow-up compared with individuals who were E6 negative at both time points (P = 0.03; κ = 0.9).

Conclusions: The presence of antibodies to HPV-16 E6 and E7 is associated with HPV in tumor cells and with better clinical outcomes. These findings suggest that the presence of E6/E7 antibodies before treatment is predictive of better clinical outcomes and that they may serve as biomarkers for selecting targeted therapeutic modalities developed for HPV-associated tumors. (Cancer Epidemiol Biomarkers Prev 2008;17(8):2087–96)
Measurement of Sex Steroid Hormones in Breast Adipocytes: Methods and Implications
Authors: Falk Roni T. , Gentzschein Elisabet , Stanczyk Frank Z. , Brinton Louise A. , Garcia-Closas Montserrat , Ioffe Olga B. , Sherman Mark E.
Published: August 2008

Background: The lack of validated methods for measuring sex steroid hormones in breast tissue has limited our knowledge of their role in the development of breast cancer. We explored the feasibility of measuring hormones in breast adipocytes for epidemiologic and clinical studies by refining an existing assay procedure and assessing the reliability of hormone measurements using the modified assay. This report presents the reproducibility of measurements of androstenedione (A), testosterone (T), estrone (E1), and estradiol (E2), using breast adipose tissue samples obtained from women undergoing surgical resection for a variety of pathologic conditions.

Methods: Breast adipose tissues were obtained from 20 women. Measurements of the steroid hormones were carried out by harvesting oil from adipocytes following enzymatic digestion of the adipose tissue, extracting and chromatographing the steroids, and quantifying them by RIA. The study was conducted in three phases: first, samples from five women were used to assess the assay procedure; following this, tissues from an additional five women were assayed repeatedly to determine reproducibility of the hormone measurements. Finally, using samples from 10 women undergoing surgical resection of a breast tumor, we evaluated hormone concentrations in samples distal and proximal to the tumor. The assay coefficient of variation and intraclass correlation coefficient were used to assess hormone reproducibility.

Results: The within-batch coefficients of variation ranged from 5% to 17%, and between-batch estimates were between 2% and 10%, suggesting that E1, E2, A, and T can be reliably measured in breast adipocytes. Among samples obtained from women undergoing surgical resection of a breast tumor, hormone levels did not differ between adipose tissue fragments that were distal or proximal to the tumor, with the possible exception of E1 in which levels were 10% higher in distal fragments.

Conclusion: These data support the feasibility of measuring steroid hormone concentrations in breast adipocytes in epidemiologic studies. Future investigations that include the measurement of hormones in the breast microenvironment may have value in understanding breast carcinogenesis, developing prevention strategies, and assessing hormonal treatments. (Cancer Epidemiol Biomarkers Prev 2008;17(8):1891–5)