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Biomedical subjects

G W Comstock

Publications and source records attributed to G W Comstock.

At least 19 recordsLinked to original sources
PubMed1992

Cancer of the pancreas and drinking water: a population-based case-control study in Washington County, Maryland.

A case-control study was done to assess a potential association between drinking water and pancreatic cancer in Washington County, Maryland. Cases of pancreatic cancer occurring from 1975 through 1989 were identified from the cancer registry. Controls were selected from the private 1975 census of Washington County. There were 101 cases and 206 controls. Chlorinated municipal water was used as a source of drinking water by 79% of cases and 63% of controls, yielding a significant odds ratio of 2.2. Adjustment for age and smoking had almost no effect on the risk, although both age and smoking were independently associated with an increased risk of pancreatic cancer. Although these findings must be interpreted with caution because of limitations in exposure assessment, these results have implications for the prevention of pancreatic cancer because chlorination of water is so widely practiced.

Adult↗
PubMed1992

Childhood weight and growth rate as predictors of adult mortality.

The effect of rate of growth and relative weight in childhood on adult mortality was studied among 13,146 persons whose weights and heights were measured between the ages of 5 and 18 years in Hagerstown, Maryland, during the period 1933-1945. Relative weight was defined internally, age- and sex-specific Z-scores for height and weight were calculated using national standards, and height and weight velocities were measured as annual increments. Associations between growth parameters (pre- and postpubertal) and mortality through 1985 were investigated in subjects who matched the 1963 and 1975 private health censuses of Washington County, Maryland, using a nested case-control design. Odds ratios of mortality increased linearly with prepubertal relative weight (p less than 0.05 for both sexes combined) and with postpubertal relative weight in females (p less than 0.01). The associations between growth velocities or attained height with mortality tended to be inverse, although not statistically significant. These results are compatible with the existence of positive associations of overweight in school-age children with long-term mortality and seem to allay fears that harm could come from increased growth rates in childhood. Without jeopardizing growth, the avoidance of overweight in childhood might reduce mortality in middle age.

Adolescent↗
PubMed1992

Serum retinol, beta-carotene, vitamin E, and selenium as related to subsequent cancer of specific sites.

Case-control differences in prediagnostic serum levels of retinol, beta-carotene, vitamin E, and selenium are compared for 10 cancer sites in 10 study populations. For all four nutrients, the majority of results showed lower levels among persons who subsequently became cases than among controls. Low levels of beta-carotene were most likely to be associated with subsequent cancer, but there were marked differences by cancer site. The results indicate that it is unlikely that any of these serum micronutrients are associated with protection against carcinogenesis at all sites. A plea is made for greater emphasis on replication of results, for reporting findings for all sites no matter how small the number of cases may be, and for keeping constantly in mind the fact that observational associations are not necessarily causal in nature.

Antioxidants↗
PubMed1992

Relationship of prediagnostic serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate to the risk of developing premenopausal breast cancer.

Dehydroepiandrosterone and dehydroepiandrosterone sulfate are steroids which may be associated with the development of breast cancer. To examine the association between serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate and the risk of developing premenopausal breast cancer, we measured hormone levels in 15 women who donated blood to a community-based serum bank in 1974 and who subsequently developed premenopausal breast cancer and in 29 matched controls from the same group of volunteers. The mean serum level of dehydroepiandrosterone among cases was 10% lower than among controls. The risk of developing breast cancer for women in the highest tertile compared with the lowest tertile of serum dehydroepiandrosterone was 0.40 with a suggestion of a dose-response trend with increasing levels. No consistent association between dehydroepiandrosterone sulfate and the risk of premenopausal breast cancer was evident. In contrast to postmenopausal breast cancer, a protective effect of dehydroepiandrosterone against premenopausal breast cancer is suggested, but because of the small sample size, the results of this study need to be replicated by others.

Adolescent↗
PubMed1992

Skinfold thickness and cardiovascular risk factors in American and Japanese telephone company executives.

Data from a cross-sectional study of cardiovascular disease risk factors in 962 US and 827 Japanese male telephone company executives were used to determine the associations of skinfold thickness measurements (abdominal, subscapular, triceps, ulnar) with blood pressure, blood glucose, serum cholesterol, and serum triglycerides. These associations were assessed within each group of executives and were compared between the groups. Most skinfolds showed association with risk factors in univariate regression. After adjusting for age and body mass index, the abdominal skinfold continued to be significantly associated with blood pressure and triglycerides in both groups, while the subscapular skinfold showed associations only with triglycerides. After adjustment, the peripheral skinfolds showed no association with risk factors in the US men, however, in the Japanese men the ulnar skinfold continued to be associated with blood pressure. These findings suggest that abdominal and ulnar skinfold measurement may be useful in adjusting for the effect of obesity on coronary heart disease risk in epidemiological studies.

Administrative Personnel↗
PubMed1992

Prediagnostic serum levels of 1,25-dihydroxyvitamin D and malignant melanoma.

A prospective nested case-control study of the relationship between prediagnostic serum levels of 1,25-dihydroxyvitamin D and subsequent development of malignant melanoma was done to test the hypothesis that increased levels are protective. Serum from 23 cases of malignant melanoma that developed between 1975 and 1987 in donors to the Washington County, Maryland serum bank was assayed along with that from 46 matched controls. There were no demonstrable differences among controls by sex, age, smoking or use of multivitamin supplements. The mean serum levels of 1,25-dihydroxyvitamin D were only 5% lower among cases than controls, a difference that could easily have occurred by chance.

Adolescent↗
PubMed1991

Epstein-Barr virus antibody patterns preceding the diagnosis of non-Hodgkin's lymphoma.

Immunosuppressed patients who develop non-Hodgkin's lymphoma (NHL) have abnormal antibody responses against the Epstein-Barr virus (EBV) prior to the diagnosis of malignancy. To see if this is also true of "spontaneous" cases in the general population, we undertook a collaborative serologic case-control study. From 4 serum banks containing specimens from over 240,000 persons, 104 subjects were identified for whom a blood specimen had been stored an average of 63 months before diagnosis of NHL, and 259 controls matched for age, sex, ethnic group and date of serum collection. The relative risks (RR) for subsequent development of NHL associated with elevated levels of IgG and IgM antibodies against viral capsid antigen were 2.5 (95% confidence interval = 1.1-5.7) and 3.2 (1.3-7.5), respectively; these associations increased with age at diagnosis. For the nuclear antigen, the distribution of titers for cases was more restricted than that of controls, with fewer cases having either elevated or low titers, RR = 0.5 (0.2-1.4) and 0.5 (0.2-1.2), respectively. Cases had significantly lower antibody titers against the cytomegalovirus, RR = 0.4 (0.2-0.9). These findings suggest that, at least for some patients, NHL is preceded by an enhanced level of endogenous immunosuppression with resultant EBV activation. This observation supports the role of EBV either directly in the development of NHL or as a primary marker of immune dysfunction.

Adult↗
PubMed1991

A longitudinal study of risk factors for depressive symptomatology in elderly widowed and married women.

Few studies have examined whether risk factors for depressive symptomatology differ in bereaved and nonbereaved individuals or whether risk factors differ in bereaved individuals over time. Between 1979 and 1983 in Washington County, Maryland, the associations between various health and social network variables and depressive symptomatology were evaluated prior to bereavement and at 1 and 12 months after bereavement in 136 widows and 409 married controls. Prior Center for Epidemiologic Studies Depression Scale scores were generally a good predictor of subsequent scores; however, shortly after bereavement prior scores proved relatively uninformative as most widows experienced a marked increase in depressive symptomatology. Poor health and limitations in physical activity at baseline were consistently associated with higher levels of symptomatology. Although having more friends was also consistently associated with lower levels of symptomatology, the effect of family size appeared to be time and circumstance specific. These results suggest that women at risk of prolonged depression after the death of their husbands can be identified prior to or at the time of bereavement and that widows have risk factors similar to those of women at risk of depression in the general community.

Aged↗
PubMed1991

Factors associated with high density lipoprotein cholesterol in Japanese and American telephone executives.

The association of plasma high density lipoprotein cholesterol (HDL cholesterol) with several factors was examined in a cross-sectional study of Japanese and American telephone executives. Mean HDL cholesterol levels were similar in both groups of men and were negatively associated with body mass index, smoking, and serum uric acid and positively associated with alcohol and exercise. These associations did not differ between the Japanese and the American men. The mean HDL cholesterol level was 4.2 mg/dl lower in the Japanese than in the American men after adjusting for age, body mass index, alcohol, smoking, exercise, and serum uric acid. The difference in HDL cholesterol between Japanese and American men in this study is inconsistent with the much lower coronary heart disease mortality in Japan and with previous comparison studies of these two populations. Most previous studies have not adjusted for important confounders, but the selective nature of our study groups may have also contributed to this inconsistency. These racial differences in HDL cholesterol may also be due to either genetic or unmeasured environmental and cultural differences. Given the similarity in HDL cholesterol levels between these two groups, our results suggest that HDL cholesterol does not play an important role in the lower coronary heart disease mortality in Japanese men.

Adult↗
PubMed1991

Serum levels of dehydroepiandrosterone and its sulfate and the risk of developing bladder cancer.

Dehydroepiandrosterone and dehydroepiandrosterone sulfate are endogenous steroids largely produced in the adrenal cortex and excreted in the urine. Many studies have demonstrated that administration of dehydroepiandrosterone to animals protects against a variety of chemical carcinogens. Epidemiological studies suggest that the circulating levels of these steroids in humans are related to the risk of developing some cancers and of dying from atherosclerotic cardiovascular disease. We measured serum levels of both of these steroids in 35 individuals who donated serum to a community-based serum bank in 1974 and who subsequently developed bladder cancer and in 69 matched controls from the same cohort of volunteers. Prediagnostic serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate were significantly lower among cases compared with controls. The risk of developing bladder cancer increased monotonically with decreasing serum levels of both steroids. The observed associations were not affected by adjustment for smoking or the time interval between serum collection and diagnosis. These results support a role for dehydroepiandrosterone and/or dehydroepiandrosterone sulfate in the prevention of bladder cancer.

Aged↗
PubMed1991

A longitudinal study of the prevalence of depressive symptomatology in elderly widowed and married women.

The expected duration and magnitude of elevations in depressive symptomatology following bereavement have not been fully characterized. This study describes the natural history of changes in depressive symptomatology after widowhood, using the Center for Epidemiologic Studies Depression Scale. We studied 1144 elderly married women who completed a baseline interview; 136 women who were subsequently widowed, and a subset of 409 still-married women, selected as controls, were reinterviewed at 1, 6, 12, 18, and 24 months after bereavement. Widows were more depressed than their married controls at every interview, including baseline. About 10% of married women had high scores (> 15) at each interview. One month after bereavement, the proportion of widows with high scores rose to 58%; this proportion declined but remained elevated at 6 months. By 12 months, the proportion with high scores was comparable with prebereavement levels. Only about 40% of the elevation in widows' scores at 12 months is potentially attributable to bereavement.

Aged↗
PubMed1991

A longitudinal study of pulmonary function in fire fighters.

Pulmonary function changes among fire fighters were evaluated by re-examining 632 Baltimore city fire fighters six to ten years after a baseline examination. Spirometry was used to determine forced expiratory volume in 1 second (FEV1). Information about exposures was obtained by questionnaire and by combining data from fire department records regarding the number of fires fought by fire fighting units with individual work histories. Men who never wore a mask while extinguishing fires experienced a 1.7 times greater rate of FEV1 decline than mask wearers. Men with ammonia exposure experienced a rate of decline 1.7 times greater than non-exposed men. Neither length of time spent in exposed jobs nor number of responses were associated with the rate of decline. Active fire fighters experienced a rate of decline 2.5 times greater than those who had retired or resigned. Some effects differed between men who were able to perform repeatable pulmonary function tests and those who were not.

Adult↗
PubMed1991

Epstein-Barr virus antibody patterns preceding the diagnosis of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) patients have elevated IgG and IgA antibody titers against the Epstein-Barr viral capsid antigen (VCA) and the diffuse component of the early antigen complex (EA-D) at diagnosis. Several studies have implied that the presence of anti-VCA-IgA can be used as a screening marker for early NPC. To evaluate this further, we undertook a serologic case-control study based on four serum banks which together had specimens from over 240,000 persons. Seven cases of undifferentiated or poorly differentiated NPC were diagnosed in the period after serum collection ranging from 26 months to 154 months. Two controls per case matched on serum bank, age, sex, race, and date of serum collection were selected by a predetermined random process. For anti-VCA-IgG, the geometric mean titer for cases (88.3) was significantly higher than that for controls (75.5, P less than 0.05). The difference was greatest among the Asian patients. No significant differences were found for anti-VCA-IgA, anti-EA-D, and anti-EA-R or anti-EBNA. No time effects were evident when titers were plotted against time of blood collection preceding diagnosis. Our results do not suggest EBV activation in the period preceding NPC diagnosis, nor that detectable IgA antibody against VCA is a marker for early disease.

Adult↗