Biomedical subjects

B Rosner

Publications and source records attributed to B Rosner.

At least 55 records · Page 3Linked to original sources

PubMed1999

Obsessive-compulsive symptoms in Prader-Willi and "Prader-Willi-Like" patients.

OBJECTIVE: To compare obsessive-compulsive (OC) symptoms in patients with Prader-Willi syndrome (PWS) and symptoms in a group of patients presenting with "Prader-Willi-like" features but without the genetic abnormalities associated with PWS. METHOD: 16 patients aged 4 through 20 years were evaluated in a clinic specializing in the assessment and management of behavioral and food-related problems in PWS. Eight patients were found to have key features of the syndrome but did not have a PWS genotype. These PWS-like subjects were matched to 8 clinic patients with a confirmed deletion of the PWS critical region of the paternally derived chromosome 15. All subjects were evaluated for obesity, IQ, food-related problems, maladaptive behaviors, and non-food-related OC symptoms. RESULTS: There were no differences between the 2 groups with respect to measures of obesity, IQ, food-related difficulties, or overall maladaptive behaviors. The PWS group showed significantly greater numbers of OC symptoms and greater symptom severity. CONCLUSIONS: Patients with PWS have elevated numbers of OC symptoms and significant symptom-related impairment which are not explained by developmental delay, food-related difficulties, or obesity. OC symptoms are part of a behavioral phenotype that accompanies deletions on the proximal long arm of chromosome 15 in PWS.

Adolescent↗

PubMed1999

A prospective study of vitamin supplement intake and cataract extraction among U.S. women.

We prospectively examined the association between vitamin supplement intake and the incidence of cataract extraction during 12 years of follow-up in a cohort of 47,152 female nurses. Women were 45 years or older and free of diagnosed cancer in 1980; others were added as they reached 45 years of age, for a total of 73,956 women. During 720,082 years of follow-up, 1,377 senile cataracts were diagnosed and extracted. Those who used multivitamins or separate supplements of vitamin C, E, or A did not have decreased risks of cataract as compared with nonusers even for use of 10 or more years. After adjusting for cataract risk factors, including cigarette smoking, body mass index, and diabetes mellitus, users of vitamin C supplements for 10 or more years had a relative risk (RR) of 0.95 [95% confidence interval (CI) = 0.76-1.20]. Associations were stronger among long-term vitamin C supplement users who were never-smokers (RR = 0.71; 95% CI = 0.47-1.08) and less than 60 years of age (RR = 0.72; 95% CI = 0.49-1.04). These findings suggest that there is little overall benefit of long-term use of vitamin supplements for risk of cataracts requiring extraction.

Adult↗

PubMed1998

Effect of vitamin A supplementation on rhodopsin mutants threonine-17 --> methionine and proline-347 --> serine in transgenic mice and in cell cultures.

A therapeutic effect of vitamin A supplementation on the course of photoreceptor degeneration, previously reported for patients with retinitis pigmentosa, was tested in two transgenic mouse models of this disease, each carrying a dominant rhodopsin mutation. The threonine-17 --> methionine (T17M) mutation is a class II rhodopsin mutation, characterized by a thermal instability/folding defect and minimal regeneration with the chromophore. The proline-347 --> serine (P347S) mutation belongs to class I, comprised of a smaller number of mutations that exhibit no recognized biochemical abnormality in vitro. In the present study, each of the two mouse models was fed a diet containing 2.5 mg of vitamin A palmitate (control) or 102.5 mg of vitamin A palmitate (high vitamin A) per kilogram of diet. Dark-adapted, full-field electroretinograms showed that the high vitamin A diet significantly reduced the rate of decline of a-wave and b-wave amplitudes in the T17M mice but had no significant effect on the decline of electroretinogram amplitude in the P347S mice. Correspondingly, histologic evaluation revealed that the treatment was associated with significantly longer photoreceptor inner and outer segments and a thicker outer nuclear layer in the T17M mice but had no effect on photoreceptor morphology in the P347S mice. In a separate series of experiments, the instability defect of the T17M mutant opsin expressed in vitro was partially alleviated by inclusion of 11-cis-retinal in the culture media. These results show that vitamin A supplementation slows the rate of photoreceptor degeneration caused by a class II rhodopsin mutation. Vitamin A supplementation may confer therapeutic benefit by stabilizing mutant opsins through increased availability of the chromophore.

Animals↗

PubMed1998

Circulating concentrations of insulin-like growth factor-I and risk of breast cancer.

BACKGROUND: Insulin-like growth factor (IGF)-I, a mitogenic and antiapoptotic peptide, can affect the proliferation of breast epithelial cells, and is thought to have a role in breast cancer. We hypothesised that high circulating IGF-I concentrations would be associated with an increased risk of breast cancer. METHODS: We carried out a nested case-control study within the prospective Nurses' Health Study cohort. Plasma concentrations of IGF-I and IGF binding protein 3 (IGFBP-3) were measured in blood samples collected in 1989-90. We identified 397 women who had a diagnosis of breast cancer after this date and 620 age-matched controls. IGF-I concentrations were compared by logistic regression with adjustment for other breast-cancer risk factors. FINDINGS: There was no association between IGF-I concentrations and breast-cancer risk among the whole study group. In postmenopausal women there was no association between IGF-I concentrations and breast-cancer risk (top vs bottom quintile of IGF-I, relative risk 0.85 [95% CI 0.53-1.39]). The relative risk of breast cancer among premenopausal women by IGF-I concentration (top vs bottom tertile) was 2.33 (1.06-5.16; p for trend 0.08). Among premenopausal women less than 50 years old at the time of blood collection, the relative risk was 4.58 (1.75-12.0; p for trend 0.02). After further adjustment for plasma IGFBP-3 concentrations these relative risks were 2.88 and 7.28, respectively. INTERPRETATION: A positive relation between circulating IGF-I concentration and risk of breast cancer was found among premenopausal but not postmenopausal women. Plasma IGF-I concentrations may be useful in the identification of women at high risk of breast cancer and in the development of risk reduction strategies. Additional larger studies of this association among premenopausal women are needed to provide more precise estimates of effect.

Breast Neoplasms↗

PubMed1998

Body weight, weight change, and risk for hypertension in women.

BACKGROUND: Obesity increases the risk for hypertension, but the effects of modest long-term weight changes have not been precisely quantified. OBJECTIVE: To investigate body mass index (BMI) and weight change in relation to risk for hypertension. DESIGN: Cohort study. SETTING: General community. PARTICIPANTS: Cohort of 82,473 U.S. female nurses 30 to 55 years of age followed every 2 years since 1976. The follow-up rate was 95%. MEASUREMENTS: Primary risk factors examined were 1) BMI at age 18 years and midlife and 2) long-term and medium-term weight changes. The outcome was incident cases of hypertension. RESULTS: By 1992, 16,395 incident cases of hypertension had been diagnosed. After adjustment for multiple covariates, BMI at 18 years of age and midlife were positively associated with occurrence of hypertension (P for trend < 0.001). Long-term weight loss after 18 years of age was related to a significantly lower risk for hypertension, and weight gain dramatically increased the risk for hypertension (compared with weight change < or = 2 kg, multivariate relative risks were 0.85 for a loss of 5.0 to 9.9 kg, 0.74 for a loss > or = 10 kg, 1.74 for a gain of 5.0 to 9.9 kg, and 5.21 for a gain > or = 25.0 kg). Among women in the top tertile of baseline BMI at age 18 years, weight loss had a greater apparent benefit. The association between weight change and risk for hypertension was stronger in younger (< 45 years of age) than older women (> or = 55 years of age). Medium-term weight changes after 1976 showed similar relations to risk for hypertension. CONCLUSIONS: Excess weight and even modest adult weight gain substantially increase risk for hypertension. Weight loss reduces the risk for hypertension.

Adult↗

PubMed1998

Percentiles for body mass index in U.S. children 5 to 17 years of age.

OBJECTIVES: It has been recommended that body mass index (BMI) (weight in kilograms/height in meter2) be used routinely to evaluate obesity in children and adolescents. This report describes the distribution of BMI in children and adolescents in the United States. METHODS: Standardized measurements of height and weight from 9 large epidemiologic studies including 66,772 children age 5 to 17 years were used to develop tables for the distributions of BMI that are age, race, and gender specific. RESULTS: The mean BMI increases with age and is slightly higher for girls than boys. Mean BMI for black and Hispanic girls was noticeably higher than for white girls. The percentiles of BMI are consistently higher than those based on the NHANES I measures, particularly for the 95th percentile. The proportion of obese children compared with NHANES I standards is higher and is highest for Hispanic boys and black and Hispanic girls. CONCLUSION: The tables and figures will allow pediatricians to determine the relative ranking of BMI for patients compared with values derived from a large sample of healthy children and adolescents. The identified gender and ethnic differences may be guides to understanding the cause and prevention of obesity.

Adolescent↗

PubMed1998

Association of family history and other risk factors with breast cancer risk (Sweden).

OBJECTIVES: Women with a family history of breast cancer have an increased risk for the disease. However, the combined impact of family history and other risk factors on breast cancer risk is unclear. We conducted a large epidemiologic study to examine this issue. METHODS. In a population-based case-control study in all of Sweden, 3,345 women aged 50 to 74 years with invasive breast cancer (84 percent of all eligible), and 3,454 controls of similar age (82 percent of all selected) were included. Mailed questionnaires and telephone interviews were used to collect detailed information on potential breast cancer risk factors. Odds ratios (OR) and 95 percent confidence intervals (CI) were estimated through multiple logistic regression. RESULTS: Women with a history of breast cancer in any first-degree relative had an increased risk of breast cancer compared with those without such a history (OR = 1.96, CI = 1.67-2.30). There was no clear indication of a differential impact of hormonal risk factors (age at menarche, parity, age at first birth, age at menopause, use of exogenous hormones, and weight gain) or body build at age seven among women with and without a positive family history. Yet, benign breast disease and height clearly were related to breast cancer risk in subjects without a family history, whereas seemingly not so in women with a family history. Formal tests for interaction between family history and these factors, however, did not prove statistically significant. CONCLUSIONS: Our findings indicate that established risk factors entail similar associations with breast cancer risk among women with and without family history of the disease.

Aged↗

PubMed1998

Deletion of repeats in the alpha C protein enhances the pathogenicity of group B streptococci in immune mice.

The alpha C protein is a protective surface-associated antigen of group B streptococci (GBS). The prototype alpha C protein of GBS (strain A909) contains nine identical tandem repeats, each comprising 82 amino acids, flanked by N- and C-terminal domains. Clinical isolates of GBS show variable numbers of repeats with a normal distribution and a median of 9 to 10 repeats. Here, we show that escape mutants of GBS expressing one-repeat alpha C protein were 100-fold more pathogenic than GBS expressing wild-type nine-repeat alpha C protein in neonatal mice whose dams were immunized with antiserum elicited to nine-repeat alpha C protein (50% lethal doses of 1.6 x 10(3) and 1.8 x 10(5), respectively; P = 0.0073). There was no difference in pathogenicity in nonimmune mice. Enzyme-linked immunosorbent assay inhibition showed that nine-repeat but not one-repeat alpha C protein is readily available for antibody binding on the surface of intact GBS. Immune electron microscopy studies with antibodies to the capsular polysaccharide (CPS) and to the alpha C protein demonstrated localization of the nine-repeat alpha C protein and the CPS at similar distances from the cell wall. The one-repeat alpha C protein was visualized poorly and only in close proximity to the cell wall, thus suggesting that antibody binding to the protein was hindered by CPS or other cell surface components. We concluded that deletion in the repeat region of the alpha C protein enhanced the pathogenicity of GBS in immune mice by (i) loss of a protective (conformational) epitope(s) and (ii) loss of antibody binding to the alpha C protein due to a decrease in antigen size relative to cell wall components and/or CPS.

Animals↗

PubMed1998

Effect on blood pressure of potassium, calcium, and magnesium in women with low habitual intake.

In populations, dietary intakes of potassium, calcium, and magnesium each have been inversely associated with blood pressure. However, most clinical trials in normotensive populations have not found that dietary supplements of these minerals lowered blood pressure. We tested the hypothesis that normotensive persons who have low habitual intake of these minerals would be particularly responsive to supplementation. Three hundred normotensive women in the Nurses Health Study II (mean age, 39 years), whose reported intakes of potassium, calcium, and magnesium were between the 10th and 15th percentiles, received for 16 weeks' duration daily supplements of either potassium 40 mmol, calcium 30 mmol (1200 mg), magnesium 14 mmol (336 mg), all three minerals together or placebos. At baseline, mean (+/-SD) 24-hour ambulatory blood pressures were 116+/-8 and 73+/-6 mm Hg systolic and diastolic, respectively, and mean dietary intakes of potassium, calcium, and magnesium were 62+/-20 mmol/d, 638+/-265 mg/d, and 239+/-79 mg/d, respectively. The mean differences (with 95% confidence intervals) of the changes in systolic and diastolic blood pressures between the treatment and placebo groups were significant for potassium, -2.0 (-3.7 to -0.3) and -1.7 (-3.0 to -0.4), but not for calcium, -0.6 (-2.2 to 1.0) and -0.7 (-2.0 to 0.6), or for magnesium, -0.9 (-2.6 to 0.8) and -0.7 (-2.2 to 0.8). The administration of calcium and magnesium with potassium did not enhance the effect of potassium alone, and the changes in blood pressure were not significant -1.3 (-3.0 to 0.4) and -0.9 (-2.2 to 0.4). In conclusion, potassium, but not calcium or magnesium supplements, has a modest blood pressure-lowering effect in normotensive persons with low dietary intake. This study strengthens evidence for the importance of potassium for blood pressure regulation in the general population.

Adult↗

PubMed1998

Genetic epidemiology of severe, early-onset chronic obstructive pulmonary disease. Risk to relatives for airflow obstruction and chronic bronchitis.

Severe alpha-1-antitrypsin deficiency is the only proven genetic risk factor for chronic obstructive pulmonary disease (COPD). We have assembled a cohort of 44 probands with severe, early-onset COPD, who do not have severe alpha-1-antitrypsin deficiency. A surprisingly high prevalence of females (79.6%) was found. Assessment of the risk to relatives of these early-onset COPD probands for airflow obstruction and chronic bronchitis was performed to determine whether significant familial aggregation for COPD, independent of alpha-1-antitrypsin deficiency, could be demonstrated. First- degree relatives of early-onset COPD probands had significantly lower FEV1 and FEV1/FVC values than control subjects (p < 0.01), despite similar pack-years of smoking. Reduced spirometric values in first-degree relatives of early-onset COPD probands were found only in current or ex-cigarette smokers. The mean FEV1 in current or ex-smoking first-degree relatives was 76.1 +/- 20.9% predicted compared to 89.2 +/- 14.4% predicted in current or ex-smoking control subjects (p < 0.01); in lifelong nonsmokers, the mean FEV1 was 93.4% predicted for both control subjects and first-degree relatives of early-onset COPD probands. Generalized estimating equations, adjusting for age and pack-years of smoking, demonstrated increased odds of reduced FEV1 and chronic bronchitis in current or ex-smoking first-degree relatives of early-onset COPD probands. Using a new method to estimate relative risk from relative odds, we estimate that the relative risks for FEV1 below 60%, FEV1 below 80%, and chronic bronchitis are each approximately three in current or ex-smoking first-degree relatives of early-onset COPD probands. The increased risk to relatives of early-onset COPD probands for reduced FEV1 and chronic bronchitis, limited to current or ex-smokers, suggests genetic risk factor(s) for COPD that are expressed in response to cigarette smoking.

Bronchitis↗

PubMed1997

Inactivation of the alpha C protein antigen gene, bca, by a novel shuttle/suicide vector results in attenuation of virulence and immunity in group B Streptococcus.

The alpha C protein of group B Streptococcus (GBS) is a major surface-associated antigen. Although its role in the biology and virulence of GBS has not been defined, it is opsonic and capable of eliciting protective immunity. The alpha C protein is widely distributed among clinical isolates and is a potential protein carrier and antigen in conjugate vaccines to prevent GBS infections. The structural gene for the alpha C protein, bca, has been cloned and sequenced. The protein encoded by bca is related to a class of surface-associated proteins of gram-positive cocci involved in virulence and immunity. To investigate the potential roles of the alpha C protein, bca null mutants were generated in which the bca gene was replaced with a kanamycin resistance cassette via homologous recombination using a novel shuttle/suicide vector. Studies of lethality in neonatal mice showed that the virulence of the bca null mutants was attenuated 5- to 7-fold when compared with the isogenic wild-type strain A909. Significant differences in mortality occurred in the first 24 h, suggesting that the role of the alpha antigen is important in the initial stages of the infection. In contrast to A909, bca mutants were no longer killed by polymorphonuclear leukocytes in the presence of alpha-specific antibodies in an in vitro opsonophagocytic assay. In contrast to previous studies, alpha antigen expression does not appear to play a role in resistance to opsonophagocytosis in the absence of alpha-specific antibodies. In addition, antibodies to the alpha C protein did not passively protect neonatal mice from lethal challenge with bca mutants, suggesting that these epitopes are uniquely present within the alpha antigen as expressed from the bca gene. Therefore, the alpha C protein is important in the pathogenesis of GBS infection and is a target for protective immunity in the development of GBS vaccines.

Animals↗

PubMed1997

Dual effects of weight and weight gain on breast cancer risk.

CONTEXT: Breast cancer is a major cause of mortality among women. It is important to identify modifiable risk factors for this disease. OBJECTIVE: To examine body mass index (BMI) at the age of 18 years and at midlife and adult weight change in relation to breast cancer incidence and mortality. DESIGN: Cohort study. SETTING: A cohort of 95256 US female nurses aged 30 to 55 years who were followed up for 16 years. MAIN OUTCOME MEASURE: Incident and fatal breast cancer. RESULTS: During 1203498 person-years, 2517 incident breast cancers (60% postmenopausal) were documented. Higher current BMI was associated with lower breast cancer incidence before menopause and was minimally associated with incidence after menopause. However, a stronger positive relationship was seen among postmenopausal women who never used hormone replacement (relative risk=1.59 for BMI >31 kg/m2 vs < or = 20 kg/m2; 95% confidence interval, 1.09-2.32; P for trend <.001). Higher BMI at the age of 18 years was associated with lower breast cancer incidence both before and after menopause. Weight gain after the age of 18 years was unrelated to breast cancer incidence before menopause, but was positively associated with incidence after menopause. This increased risk with weight gain was limited to women who never used postmenopausal hormones; among these women, the relative risk was 1.99 (95% confidence interval, 1.43-2.76) for weight gain of more than 20 kg vs unchanged weight (P for trend <.001). Current BMI and weight gain were even more strongly associated with fatal postmenopausal breast cancer. In this population, the percentage of postmenopausal breast cancer accounted for by weight gain alone was approximately 16% and by hormone replacement therapy alone was 5%, but when the interaction between these variables was considered, together they accounted for about one third of postmenopausal breast cancers. CONCLUSIONS: Avoiding adult weight gain may contribute importantly to the prevention of breast cancer after menopause, particularly among women who do not use postmenopausal hormones.

Adolescent↗

PubMed1997

Birth weight and risk of cardiovascular disease in a cohort of women followed up since 1976.

OBJECTIVE: To examine the association between birth weight and non-fatal adult cardiovascular disease while controlling for potential confounders such as socioeconomic group and adult lifestyle. DESIGN: Retrospective self report of birth weight in an ongoing longitudinal cohort of nurses followed up by postal questionnaire every two years. SETTING: Nurses' health study, a cohort of 121700 women followed up since 1976. MAIN OUTCOME MEASURES: Non-fatal cardiovascular disease, including myocardial infarction, coronary revascularisation, and stroke. RESULTS: Among the 70297 women free of cardiovascular disease at baseline who reported birth weight in the 1992 questionnaire there were 1309 first cases of non-fatal cardiovascular disease. Increasing birth weight was associated with decreasing risk of non-fatal cardiovascular disease. There were 1216 first cases of non-fatal cardiovascular disease among women who were singletons and had been born full term; their relative risks adjusted for several cardiovascular risk factors were 1.49 (95% confidence interval 1.05 to 2.10) for birth weight < 2268 g (< 5 lb 0 oz); 1.25 (0.98 to 1.61) for birth weight 2268-2495 g (5 lb 0 oz to 5 lb 8 oz); 1.12 (0.98 to 1.27) for birth weight > 2495-3175 g (> 5 lb 8 oz to 7 lb 0 oz); 1.00 (referent) for birth weight > 3175-3856 g (> 7 lb 0 oz to 8 lb 8 oz); 0.96 (0.80 to 1.15) for birth weight > 3856-4536 g (> 8 lb 8 oz to 10 lb 0 oz); and 0.68 (0.46 to 1.00) for birth weight > 4536 g (> 10 lb 0 oz) (P value for trend = 0.0004). The inverse trend was apparent for both coronary heart disease and stroke. CONCLUSIONS: These data provide strong evidence of an association between birth weight and adult coronary heart disease and stroke.

Adult↗

PubMed1997

Postmenopausal hormone therapy and mortality.

BACKGROUND: Postmenopausal hormone therapy has both benefits and hazards, including decreased risks of osteoporosis and cardiovascular disease and an increased risk of breast cancer. METHODS: We examined the relation between the use of postmenopausal hormones and mortality among participants in the Nurses' Health Study, who were 30 to 55 years of age at base line in 1976. Data were collected by biennial questionnaires beginning in 1976 and continuing through 1992. We documented 3637 deaths from 1976 to 1994. Each participant who died was matched with 10 controls alive at the time of her death. For each death, we defined the subject's hormone status according to the last biennial questionnaire before her death or before the diagnosis of the fatal disease; this reduced bias caused by the discontinuation of hormone use between the time of diagnosis of a potentially fatal disease and death. RESULTS: After adjustment for confounding variables, current hormone users had a lower risk of death (relative risk, 0.63; 95 percent confidence interval, 0.56 to 0.70) than subjects who had never taken hormones; however, the apparent benefit decreased with long-term use (relative risk, 0.80; 0.67 to 0.96, after 10 or more years) because of an increase in mortality from breast cancer among long-term hormone users. Current hormone users with coronary risk factors (69 percent of the women) had the largest reduction in mortality (relative risk, 0.51; 95 percent confidence interval, 0.45 to 0.57), with substantially less benefit for those at low risk (13 percent of the women; relative risk, 0.89; 95 percent confidence interval, 0.62 to 1.28). CONCLUSIONS: On average, mortality among women who use postmenopausal hormones is lower than among nonusers; however, the survival benefit diminishes with longer duration of use and is lower for women at low risk for coronary disease.

Adult↗

PubMed1997

Multivariate methods for clustered ordinal data with applications to survival analysis.

Clustered data are the rule in many clinical specialties such as ophthalmology. Methods have been developed for the treatment of clustered continuous or binary outcome data. Less attention has been given to ordinal outcomes which occur frequently in ophthalmology. For example, grading systems of cataract and diabetic retinopathy are commonly used where a photograph is graded by comparison with a series of reference photographs of increasing severity. Some commonly used methods for the analysis of ordered categorical data include the proportional odds and continuation ratio models. It is difficult, however, to incorporate clustering effects into these models. Instead, for clusters of size two, we propose a generalization of the adjacent category model given by log[Pr(i + 1,j)/Pr(i,j)] = ui + (j - 1) lambda + beta' x, where Pr(i,j) denotes the probability that the right (left) eye has grade i(j), x is a vector of (person or eye-specific) covariates for the right eye, u and beta are vectors of location and covariate parameters and lambda is a clustering parameter. Based on this model, and a similar model interchanging the role of i and j, we derived a closed-form expression for Pr(i,j) as a function of u, lambda and beta and use Newton-Raphson method to maximize the likelihood. An extension of the method allows for extra agreement along the diagonal and is then a generalization of the agreement plus linear-by-linear association model proposed by Agresti in the setting of no covariates. We apply these methods to a data set of 43 diabetic subjects from the Harvard Clinical Cataract Research Center, where cortical cataract grade was the outcome. We also extend this methodology to a survival setting, where both censored and uncensored outcomes are available for individual cluster members, and one wishes to take clustering into account. We apply the survival analysis model to a data set of 1807 children (two ears per child) in the greater Boston area, who were followed for the development of otitis media over the first year of life.

Boston↗

PubMed1997

Regression calibration method for correcting measurement-error bias in nutritional epidemiology.

Regression calibration is a statistical method for adjusting point and interval estimates of effect obtained from regression models commonly used in epidemiology for bias due to measurement error in assessing nutrients or other variables. Previous work developed regression calibration for use in estimating odds ratios from logistic regression. We extend this here to estimating incidence rate ratios from Cox proportional hazards models and regression slopes from linear-regression models. Regression calibration is appropriate when a gold standard is available in a validation study and a linear measurement error with constant variance applies or when replicate measurements are available in a reliability study and linear random within-person error can be assumed. In this paper, the method is illustrated by correction of rate ratios describing the relations between the incidence of breast cancer and dietary intakes of vitamin A, alcohol, and total energy in the Nurses' Health Study. An example using linear regression is based on estimation of the relation between ultradistal radius bone density and dietary intakes of caffeine, calcium, and total energy in the Massachusetts Women's Health Study. Software implementing these methods uses SAS macros.

Adult↗

PubMed1997

Excessive daytime sleepiness associated with idiopathic alterations of consciousness.

Sleep/wake patterns were recorded by continuous 24-hour ambulatory polysomnography in 339 patients, who had episodes of altered consciousness. Patients were recorded while they were outside the hospital. From a seven-channel montage of electrodes affixed below the hairline, sleep polygraphic EEG was easily read from T3-T4, EOG from F2-F8 and EMG from T3-T6. Sleep was staged by analysis of aural signals on 60 times real time playback, augmented by continuous visual display and selected frozen frames. Patient major sleep period patterns reflected those reported for general populations. Unexpectedly, 47% of the patients took daytime naps and 44% of the nappers took more than one nap. Naps had a mean duration of 71 minutes. Those who took no naps slept significantly longer at night by 23 min. Napping reduced night sleep much more in patients who did not take CNS-acting medications. We conclude that excessive sleepiness may in part explain complaints of episodically altered consciousness.

Adolescent↗

PubMed1997

A prospective study of reproductive factors, oral contraceptive use, and risk of colorectal cancer.

To explore the roles of reproductive factors and oral contraceptive use in the etiology of colorectal cancer, we examined incident cases of colorectal cancer (n = 501) that occurred during 1,012,280 person-years of follow-up between 1980 and 1992 in the Nurses' Health Study. The women completed mailed, self-administered questionnaires every 2 years to update information on the risk factors and major medical events. In multivariate analysis, the relative risk (RR) of colorectal cancer among women who experienced menarche at age 14 or older was 0.83 (95% confidence interval (CI) = 0.64-1.08) compared with women who had menarche at age 13; women whose menarche occurred under age 12 were at higher risk (RR = 1.22; 95% CI = 0.96-1.55, P for trend = 0.01). Compared with women whose first pregnancy was before age 24, the risk for colorectal cancer was significantly increased among women whose first pregnancy was at age 30 or older (RR = 1.57; 95% CI = 1.15-2.14; P for trend = 0.02). No important associations were seen for parity or age at menopause. Women who used oral contraceptives for 96 months or longer had a 40% lower risk of developing colorectal cancer (RR = 0.60; 95% CI = 0.40-0.89; P for trend = 0.02) compared with women who never used oral contraceptives. These prospective data suggest that a later age of menarche and use of oral contraceptives may reduce risk of colorectal cancer, whereas women with a later age at first pregnancy may have a higher risk.

Adult↗