ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Chlamydia pneumoniae(Cpn) has been proposed as a possible etiologic agent for multiple sclerosis (MS), but results of previous studies are conflicting.Methods.Using a nested case-control design, we examined the association between Cpn infection and MS in the Nurses’ Health Study (NHS) and Nurses’ Health Study II (NHS II) cohorts. Among 32,826 women in the NHS and 29,722 women in the NHS II with blood samples, 141 incident cases of definite or probable MS were documented. Each case was matched to two healthy controls on year of birth and NHS cohort. Serum samples were tested for the presence of Cpn-specific immunoglobin G antibodies using microimmunofluorescence.Results.Cpn immunoglobin G seropositivity was positively associated with risk of MS (odds ratio [OR] = 1.7; 95% confidence interval [CI] = 1.1–2.7). This association did not change after adjusting for age at blood collection, ancestry, latitude of residence at birth, and smoking (OR = 1.9; CI = 1.1–3.1). Seropositivity for Cpn was only moderately associated with risk of relapsing-remitting MS (OR = 1.7; CI = 0.9–3.2), but it was strongly associated with risk of progressive MS (OR = 7.3; CI = 1.4–37.2). Geometric mean titers of Cpn-specific immunoglobin G antibody were similar in women with relapsing-remitting MS as compared with matched controls (44vs39), but they were elevated in women with progressive MS (99vs40).Conclusions.These results support a positive association between Cpn infection and progressive MS.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Early sex hormone exposure contributes to gender-dimorphic behavioral development in mammals, including humans. Environmental toxicants concentrated in contaminated sport fish can interfere with the actions of sex steroids.Methods.This study developed an outcome variable by combining gender-dimorphic behaviors that differentiates boys and girls. Offspring of participants in the New York State Angler Cohort Study (NYSACS) were targeted in a parent-report postal survey. Instruments were selected based on findings of gender differences in the general population.Results.A linear discriminant function model incorporating three gender behavior scales correctly classified the sex of 97.7% of children (252 boys and 234 girls) from a random NYSACS sample. The discriminant function was cross-validated by correctly classifying the sex of 98.4% of children (457 boys and 425 girls) from the remaining NYSACS cases and 97.6% of children (154 boys and 142 girls) from an independent school sample. Within-sex stepwise multiple regression analyses revealed that masculine behavior increased among boys with age and with the number of years of maternal sport fish consumption. In girls, older age and previous live-born siblings were associated with more masculine behavior, whereas feminine behavior increased with the duration of breast feeding. These associations were replicated in an independent sample.Conclusions.A linear discriminant function effectively transformed the binary classification of sex (male-female) to a bipolar continuum of gender (masculinity-femininity). Findings from this study are consistent with the hypothesis that environmental contaminants contribute to shifts in gender-role behavior. Future investigations will need to account for competing explanations of this effect.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Between 1939 and the 1960s, the synthetic estrogen diethylstilbestrol (DES) was given to millions of pregnant women to prevent pregnancy complications and losses. The adverse effects of prenatal exposure on the genitourinary tract in men and the reproductive tract in women are well established, but the possible effects on psychosexual characteristics remain largely unknown.Methods.We evaluated DES exposure in relation to psychosexual outcomes in a cohort of 2,684 men and 5,686 women with documented exposure status.Results.In men, DES was unrelated to the likelihood of ever having been married, age at first intercourse, number of sexual partners, and having had a same-sex sexual partner in adulthood. DES-exposed women, compared with the unexposed, were slightly more likely to have ever married (odds ratio [OR] = 1.1; confidence interval [CI] = 1.0–1.4) and less likely to report having had a same-sex sexual partner (OR = 0.7; CI = 0.5–1.0). The DES-exposed women were less likely to have had first sexual intercourse before age 17 (OR = 0.7; CI = 0.6–0.9) or to have had more than one sexual partner (OR = 0.8; CI = 0.7–0.9). There was an excess of left-handedness in DES-exposed men (OR = 1.4; CI = 1.1–1.7) but not in DES-exposed women. DES exposure was unrelated to self-reported history of mental illness in women.Conclusions.Overall, our findings provide little support for the hypothesis that prenatal exposure to DES influences the psychosexual characteristics of adult men and women.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Most methods for calculating the sample size needed to detect gene-environment interactions use odds ratios to measure the effect size. We show that for any combination of susceptible genotype prevalence and exposure prevalence and their associated risks, the odds ratio measuring strength of interaction corresponds to a population attributable fraction (PAF) because of interaction and vice versa. Simultaneous consideration of odds ratio for interaction and the associated PAF attributable to interaction provides additional insight to investigators evaluating the feasibility and public health relevance of a proposed study.We considered gene-environment interactions on a multiplicative scale, and assumed a dichotomous environmental exposure variable and a single two-allele disease-susceptibility locus. Our results show, for example, that for studies of exposures and genotypes that are common in a population (30%–50%), the PAF for interaction is large (>27%) even if the odds ratio for interaction is only moderate (∼2). If simultaneous estimates of interaction odds ratio and PAF indicate that the PAF is so large as to be implausible, the investigator may decide to reevaluate the study design based on detecting a more reasonable PAF. In this case, the associated odds ratio for interaction will be weaker and a considerably larger sample size may be needed.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.High parity is associated with reduced risk of ovarian cancer. One hypothesis is that pregnancy is associated with clearance of a fraction of the genetically modified (premalignant) cells from the ovaries.Methods.We evaluated this hypothesis using a model that estimates the cell clearance fraction at first and second pregnancy according to age at pregnancy. The model was fitted using reproductive history data from a cohort of 1.5 million Danish women born between 1935 and 1978 and followed for 28.7 million person-years. During this follow-up period, 2,035 developed invasive ovarian cancer.Results.We found the model to have a satisfactory fit despite the very few parameters involved. The model estimated similar cell clearance fractions for the first and second pregnancy and decreasing clearance with later age at pregnancy.Conclusion.The relation of pregnancy history to risk of ovarian cancer can be well described by a cell clearance model that allows the cell clearance fraction to decrease with age at pregnancy.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID