Biomedical subjects

D Spiegelman

Publications and source records attributed to D Spiegelman.

At least 55 records · Page 3Linked to original sources

PubMed2001

The association between maternal HIV-1 infection and pregnancy outcomes in Dar es Salaam, Tanzania.

OBJECTIVE: To examine the association between maternal HIV infection and pregnancy outcomes controlling for potential confounding factors among a cohort of HIV-uninfected and HIV-infected pregnant women in Dar es Salaam, Tanzania. DESIGN: Prospective cohort study. METHODS: A cohort of 1,078 HIV-infected and 502 HIV-uninfected pregnant women between 12 and 27 weeks of gestation were enrolled and followed up until delivery. Multiple regression models were used to compare the risk of adverse pregnancy outcomes among HIV-uninfected women with those among HIV-infected women overall, and separately among asymptomatic or symptomatic HIV-infected women. RESULTS: No significant differences between HIV-uninfected women and HIV-infected women were observed in risks of fetal loss or low birthweight or in the weight, head circumference and gestational age of infants at birth. HIV-infected women were more likely to have severe immature infants (<34 weeks) than HIV-uninfected women (multivariate RR 1.54 [95% CI 0.90-2.48]; P= 0.05). There was a significantly higher risk of low birthweight (RR 2.29, 95% CI 1.34-3.92; P = 0.03) and prematurity (<37 weeks) (RR 1.93, 95% CI 1.35-2.77; P = 0.0003) among symptomatic HIV-infected women when compared with HIV-uninfected women. CONCLUSION: HIV-infected women, particularly those whoare symptomatic, are at a higher risk of adverse pregnancy outcomes.

Adult↗

PubMed2001

Association of genetic polymorphisms in UGT1A1 with breast cancer and plasma hormone levels.

UDP-glucuronosyltransferases (UGTs) catalyze the detoxification and the elimination of a large number of endogenous and exogenous compounds in the liver and extrahepatic tissues. One of the UGT1A family members, UGT1A1, is involved in estradiol metabolism and, therefore, represents a candidate gene in breast carcinogenesis. A common insertion/deletion polymorphism in the TATA-box of the promoter region of UGT1A1 results in decreased initiation of transcription. In a previous study, we found a positive association between the UGT1A1 low-transcriptional alleles and premenopausal breast cancer risk in an African-American population. In the present study, we sought to determine whether the low-transcription UGT1A1 promoter allele, UGT1A1*28 [A(TA)(7)TAA], was associated with increased breast cancer risk among primarily Caucasian women in a nested case-control study within the Nurses' Health Study cohort. No significant association between the UGT1A1*28 [A(TA)(7)TAA] allele and breast cancer was observed. Compared with women homozygous for the UGT1A1*1 [A(TA)(6)TAA] allele, the relative risk was 0.80 (confidence interval, 0.49-1.29) for women homozygous for the UGT1A1*28 allele. The effect of the UGT1A1 genotype on plasma hormone levels in postmenopausal women not using hormone replacement was also evaluated, and overall, no significant differences in hormone levels by genotypes were observed. When restricted to women who had at least one UGT1A1*28 allele and a body mass index at blood draw of >27 kg/m(2), particularly in combination with the cytochrome p450c17alpha genotype, estrone and estradiol levels tended to vary by UGT1A1 genotypes. The results presented do not support a strong association between the UGT1A1 promoter polymorphism and the risk of breast cancer.

Adult↗

PubMed2000

Prospective study of dietary supplements, macronutrients, micronutrients, and risk of bladder cancer in US men.

Data derived from laboratory investigations suggest that a number of dietary variables may contribute to bladder carcinogenesis. Although bladder cancer is the fourth leading cause of cancer in men in the United States, dietary studies are few. The authors examined the relations between intakes of macro- and micronutrients and the risk of bladder cancer among men in the prospective Health Professionals Follow-Up Study. Each participant completed a 131-item food frequency questionnaire in 1986 and in 1990, from which nutrient intakes were calculated. During 12 years of follow-up, 320 cases of bladder cancer were diagnosed. No association was observed for total caloric or macronutrient intake and bladder cancer risk. Similarly, we found no relation for dietary intake of potassium, sodium, calcium, magnesium, phosphorus, iron, or water-soluble vitamins and bladder cancer risk. Total vitamin E intake and vitamin E supplements were inversely associated with risk. In addition, a dose-response relation was observed for duration of vitamin E supplement use. A suggestive inverse association was seen with dose of vitamin C supplement use. More studies are needed to determine the role of vitamins E and C supplement intake in bladder carcinogenesis.

Adult↗

PubMed2000

Leisure-time physical activity, television watching, and plasma biomarkers of obesity and cardiovascular disease risk.

The benefits of physical activity in reducing cardiovascular disease (CVD) are thought to be mediated through changes in blood lipids, insulin sensitivity, and thrombogenic factors. Few studies have addressed the effects of both long-term physical activity and inactivity on these factors. The authors assessed associations between long-term leisure-time physical activity, television watching, and biomarkers of CVD risk among 468 healthy male health professionals. Prior to blood collection in 1993-1994, physical activity and television watching were assessed biennially from 1986 to 1994 by a questionnaire. Physical activity was expressed as metabolic equivalents-hours per week. Multivariate linear regression analyses showed that metabolic equivalents-hours in 1994 were significantly associated with high density lipoprotein cholesterol (HDL cholesterol) (positively) and with leptin and C-peptide (inversely). The average number of hours of television watching assessed in 1994 was significantly positively associated with low density lipoprotein cholesterol and significantly inversely associated with HDL cholesterol and apolipoprotein A1. Average hours of television watching per week assessed in 1988-1994 was positively associated with leptin levels (p < 0.01). The associations of television watching and vigorous activity with leptin and HDL cholesterol were independent of each other. In conclusion, physical activity and television watching were significantly associated with several biochemical markers of obesity and CVD risk.

Adult↗

PubMed2000

Dietary fat intake and endogenous sex steroid hormone levels in postmenopausal women.

PURPOSE: To examine the relationship between plasma levels of reproductive sex steroid hormones in postmenopausal women and their reported fat intake. METHODS: We measured plasma sex steroid hormones levels in plasma collected in 1989 and 1990 from 381 healthy postmenopausal women. For each woman, we measured fat intake in 1986 and 1990 by a food-frequency questionnaire. The cross-sectional associations between the percentage of energy from total and specific types of dietary fat intake and plasma hormone levels were assessed by linear regression, controlling for energy intake, obesity, and protein intake. RESULTS: The plasma estradiol level was 4.3% lower (95% confidence limits, -8.3%, -0.2%) for a substitution of 5% of energy from fat intake for an equivalent amount of energy from carbohydrate when adjusted for obesity and other covariates. Estradiol was also inversely associated with all other fat types except trans fat; the inverse associations with vegetable fat and marine omega-3 fats were statistically significant. CONCLUSION: We observed an inverse association between total fat intake averaged over 4 to 5 years and estradiol levels. This result is inconsistent with the hypothesis that fat intake predisposes to breast cancer risk by raising endogenous estrogen levels.

Adult↗

PubMed2000

Body composition and dietary intake in relation to drug abuse in a cohort of HIV-positive persons.

We examined the relationships between drug abuse, weight, body composition, and dietary intake in persons infected with HIV in a cross-sectional analysis of baseline data from a longitudinal study of nutritional status and HIV. Body composition was measured by bioelectrical impedance analysis. Dietary data were collected by 3-day food records or 24-hour recalls. We analyzed data from 39 current intravenous drug users (IVDU), 103 past intravenous drug users (past-IVDU), 239 users of nonintravenous drugs (users-NIVD), and 61 nonusers (reference category). In the men, there were no differences in weight, body mass index (BMI), or body composition among the drug-use groups. In the women, there was a trend to lower weight and BMI across the drug use categories: IVDU women had lower average weight (-13.7 kg; p = .006), BMI (-5.6 units; p = .003) and less fat mass than non-users (-9.8 kg; p = .0001). In women, drug users had higher weight-adjusted energy intakes than nonusers, whereas in the men both drug using groups, NIVD and IVDU, had higher energy intakes than nonusers. These data suggest that intravenous drug-abuse is associated with lower weight and fat mass in women with HIV infection despite adequate self-reported energy intake.

Adult↗

PubMed2000

Oral contraceptives and the incidence of multiple sclerosis.

BACKGROUND: Experimental and clinical data suggest a protective effect of estrogens on the development and progression of MS. METHODS: We assessed whether MS incidence was associated with oral contraceptive use or parity in two cohort studies of U.S. women, the Nurses' Health Study (NHS; 121,700 women aged 30 to 55 years at baseline in 1976) and the Nurses' Health Study II (NHS II; 116,671 women aged 25 to 42 years at baseline in 1989). Participants with a diagnosis of MS before baseline were excluded. Oral contraceptive history and parity were assessed at baseline and updated biennially. During follow-ups of 18 years (NHS) and 8 years (NHS II) we documented a total of 315 definite or probable cases of MS. RESULTS: Neither use of oral contraceptives nor parity were significantly associated with the risk of MS. As compared with women who never used oral contraceptives, the age-adjusted relative risk (95% CI) was 1.2 (0.9, 1.5) for past users, and 1.0 (0.6, 1.7) for current users. Similar results were obtained after adjustment for latitude, ancestry, and other potential confounding factors. There was no clear trend of MS risk with either increasing duration of use or time elapsed since last use. Age at first birth was also not associated with the risk of MS. CONCLUSIONS: These prospective results do not support a lasting protective effect of oral contraceptive use or pregnancy on the risk of MS. The decision to use hormonal contraception should not be affected by its effects on the risk of MS.

Adult↗

PubMed2000

Pooled analysis of prospective cohort studies on height, weight, and breast cancer risk.

The association between anthropometric indices and the risk of breast cancer was analyzed using pooled data from seven prospective cohort studies. Together, these cohorts comprise 337,819 women and 4,385 incident invasive breast cancer cases. In multivariate analyses controlling for reproductive, dietary, and other risk factors, the pooled relative risk (RR) of breast cancer per height increment of 5 cm was 1.02 (95% confidence interval (CI): 0.96, 1.10) in premenopausal women and 1.07 (95% CI: 1.03, 1.12) in postmenopausal women. Body mass index (BMI) showed significant inverse and positive associations with breast cancer among pre- and postmenopausal women, respectively; these associations were nonlinear. Compared with premenopausal women with a BMI of less than 21 kg/m2, women with a BMI exceeding 31 kg/m2 had an RR of 0.54 (95% CI: 0.34, 0.85). In postmenopausal women, the RRs did not increase further when BMI exceeded 28 kg/m2; the RR for these women was 1.26 (95% CI: 1.09, 1.46). The authors found little evidence for interaction with other breast cancer risk factors. Their data indicate that height is an independent risk factor for postmenopausal breast cancer; in premenopausal women, this relation is less clear. The association between BMI and breast cancer varies by menopausal status. Weight control may reduce the risk among postmenopausal women.

Adult↗

PubMed2000

Adiposity and mortality in men.

The relation between measures of adiposity and mortality has been a controversial topic. The authors examined prospectively the relation between several measures of adiposity and risks of overall and cause-specific mortality in 39,756 US men aged 40-75 years. During 10 years of follow-up (1986-1996), 1,972 deaths (747 from cancer, 423 from cardiovascular disease, and 802 from other causes) were documented. An elevated risk of death among the leanest men was partly accounted for by excess mortality during early follow-up and high mortality among those with a history of recent weight loss. After exclusion of men with substantial recent weight loss and deaths occurring during the first 4 years of follow-up, overall and cardiovascular disease mortality among men aged <65 years increased linearly with greater body mass index (BMI) (weight (kg)/height (m)2); multivariate relative risks for overall mortality were 1.0 (referent) for a BMI of <23, 1.21 for a BMI of 23-24.9, 1.19 for a BMI of 25-26.9, 1.39 for a BMI of 27-29.9, and 1.97 for a BMI of >30 (test for trend: p< 0.001). Among men aged > or =65 years, there were no significant relations between BMI and overall, cardiovascular disease, or cancer mortality risk. However, waist circumference strongly predicted risk of death from cardiovascular disease among the older men. These findings indicated that the relation between body fat and mortality was influenced by reverse causation and varied by age.

Adipose Tissue↗

PubMed2000

A tetranucleotide repeat polymorphism in CYP19 and breast cancer risk.

The CYP19 gene codes for aromatase, a key steroidogenic enzyme involved in the conversion of androgens to estrogens. A tetranucleotide (TTTA) repeat polymorphism is present in intron 4 of CYP19; 2 out of 4 breast cancer case-control studies have reported a greater frequency of 2 specific alleles among affected women. We evaluated associations between CYP19 repeat alleles and breast cancer risk in a case-control study nested within the Nurses' Health Study cohort (incident cases: n=462; controls: n=618). We observed seven different CYP19 alleles (TTTA(7-13)). Compared to controls, cases had a statistically significant greater frequency of the 10 (TTTA)(10) repeat allele (10 allele: 2.3% vs. 0.7%, p = 0.005) and a nonsignificant increase in the frequency of the 12 (TTTA)(12) allele (12 allele: 3.1% vs. 2.1%, p = 0.11). A higher frequency of the 10 allele was observed in more advanced cancer cases defined as four or more involved nodes or distant metastasis [4+ nodes: 5/36 (13.9%) vs. 0-3 nodes: 13/330 (3.9%), p = 0.02]. Among controls, we found women with the 7 repeat allele to have decreased levels of estrone sulfate (-16.4%, p = 0.02), estrone (-6.1%, p = 0.22) and estradiol (-9.9%, p = 0.10), and a lower estrone/androstenedione ratio (E1/A) (-10.5%, p = 0.08) compared to non-carriers. A higher E1/A ratio and elevated estrogen levels were observed among carriers of the 8 repeat allele; E1/A ratio (+21.0%, p = 0.003), estrone (+7.5%, p = 0.16) and estradiol (+10.8%, p = 0.08). However, we observed no evidence of an association between these alleles and breast cancer risk. We were unable to make inferences regarding the effect of the 10 allele on hormone levels due to the small number of allele carriers in the subgroup with hormone levels. As this repeat polymorphism is not close to the splice sites in intron 4, linkage disequilibrium with other functional polymorphisms in CYP19 may explain the findings of an increased association between breast cancer and the 10 allele variant of CYP19. We did not detect any sequence variants in the regulatory region or in the adipose-specific exon I.4. The lack of an established effect on CYP19 function associated with the 10 allele means that these findings should be interpreted with caution.

Alleles↗

PubMed2000

Electric blanket use and breast cancer in the Nurses' Health Study.

Electric and magnetic fields (EMFs) have been hypothesized to increase the risk of breast cancer, and electric blankets represent an important source of exposure to EMFs. The authors examined the relation between electric blanket use and invasive breast cancer in the Nurses' Health Study. On the biennial questionnaire in 1992, 87,497 women provided information on this exposure during three consecutive time periods. In a prospective analysis with 301,775 person-years of follow-up through 1996 (954 cases), the relative risk for any electric blanket use was not elevated (relative risk (RR) = 1.08, 95% confidence interval (CI): 0.95, 1.24) after controlling for breast cancer risk factors. There was a weak association between breast cancer and electric blanket use at least 16 years before diagnosis and long-term use in age-adjusted analyses but not in multivariate models. In a retrospective analysis of 1,318,683 person-years of follow-up (2,426 cases), the multivariate relative risk associated with use before disease follow-up began was null (RR = 1.05, 95% CI: 0.95, 1.16). Similar results were obtained in analyses stratified by menopause and restricted to estrogen receptor-positive breast cancers. While 95% confidence intervals for these estimates did not exclude small risks, overall, results did not support an association between breast cancer risk and exposure to EMFs from electric blankets.

Adult↗

PubMed2000

Polymorphic repeat in AIB1 does not alter breast cancer risk.

STATEMENT OF FINDINGS: We assessed the association between a glutamine repeat polymorphism in AIB1 and breast cancer risk in a case-control study (464 cases, 624 controls) nested within the Nurses' Health Study cohort. We observed no association between AIB1 genotype and breast cancer incidence, or specific tumor characteristics. These findings suggest that AIB1 repeat genotype does not influence postmenopausal breast cancer risk among Caucasian women in the general population.

Adult↗

PubMed2000

Relation of lean body mass to health-related quality of life in persons with HIV.

OBJECTIVE: To determine the nature and strength of the relation between lean body mass and measures of health-related quality-of-living (HRQL) including physical functioning in men and women with HIV. DESIGN: Cross-sectional analysis using 619 patients with HIV infection from two cities in the northeastern United States. MAIN OUTCOME MEASURES: Lean body mass (LBM) was assessed by bioimpedance analysis (BIA). Physical functioning, general health perceptions, energy/fatigue, and number of days spent in bed in the last month were determined by patient self-report. RESULTS: Data from 450 men and 169 women were analyzed. Mean age was 39 years, 37.6% were nonwhite, and mean CD4 counts were 352 cells/ml. In multivariable models, higher LBM was significantly associated with better physical functioning in men but not in women. In men, a 10-kg increment in LBM was associated with a 3.7 point (95% confidence interval [CI], 0.19-7.2) increment in physical functioning (0-100 scale). In similar analyses, higher LBM was significantly associated with better general health perceptions (10-kg increment in LBM associated with a 4.8 point [95% CI, 1.4-8.1] increment in general health perceptions), and fewer days in bed in the last month (10-kg increment in LBM associated with 0.9 [95% CI, -1.8-0] fewer days in bed). Lean body mass was not independently associated with energy/fatigue. CONCLUSIONS: In this diverse population of persons with HIV, LBM was significantly related to physical functioning and other measures of HQRL in men, but not in women. In men, the relation was linear but relatively weak. These data have potential implications for assessing the clinical impact of interventions aimed at increasing LBM. Even in men, increases in LBM in the ranges that are currently achievable may produce relatively small improvements in physical functioning and other measures of HRQL.

Adipose Tissue↗

PubMed2000

Randomized trial of vitamin supplements in relation to vertical transmission of HIV-1 in Tanzania.

BACKGROUND: Observational studies suggest that poor nutritional status among HIV-infected pregnant women is associated with a higher risk of vertical transmission of HIV. METHODS: We randomized 1083 pregnant women infected with HIV-1 in a double-blind, placebo-controlled trial to examine the effects of supplements of vitamin A and/or multivitamins (excluding vitamin A) using a 2-x-2 factorial design. We report the effects of the supplements on HIV infection defined using polymerase chain reaction (PCR), or death up to 6 weeks postpartum. RESULTS: Of babies in the multivitamin arm 38, (10.1%) were HIV-positive at birth compared with 24 (6.6%) in the no-multivitamin arm (relative risk [RR] = 1.54; 95% CI, 0.94-2.51; p = .08). Of babies born to mothers in the vitamin A arm, 38 (10.0%) were HIV-positive at birth compared with 24 (6.7%) in the no-vitamin A arm (RR, 1.49; 95% CI, 0.91-2.43; p = 0.11). Neither multivitamins nor vitamin A had an effect on HIV status at 6 weeks among those who were HIV-negative at birth (RR = 1.04; 95% CI, 0.65-1.66; p = 0.88) and (RR = 1.30; 95% CI, 0.80-2.09; p = .29, respectively). Similarly, neither supplement was associated with being either HIV-infected or dead at birth (RR, 0.98; 95% CI, 0.76-1.27; p = .89 and RR, 1.01; 95% CI, 0.78-1.31; p = .95, respectively. A beneficial effect of multivitamins on birth weight was limited to babies who were HIV-negative at birth; babies in the multivitamin arm weighed +94 g more compared with those in the no-multivitamin arm (p = .02). Among babies who were HIV-positive at birth, the corresponding difference was -31 g (p = .82). CONCLUSIONS: Vitamin A and multivitamins did not affect the risk of vertical transmission of HIV in utero nor during the intrapartum and early breastfeeding periods. Multivitamins resulted in a significant improvement in birth weight of babies who were HIV-negative at birth but had no effect among those who were HIV-positive. The effect of vitamin supplements on HIV transmission through breastfeeding and on clinical progression of HIV disease is yet to be ascertained.

Adult↗

PubMed2000

Prospective study of alcohol consumption and the risk of age-related macular degeneration.

OBJECTIVE: To describe the relationship between alcohol consumption and the incidence of age-related macular degeneration (AMD). METHODS: We conducted a prospective study among female nurses between 1980 and 1994 and among male health professionals between 1986 and 1994. We included 32764 women and 29488 men who were 50 years or older, without a diagnosis of AMD or cancer at baseline, and added additional subjects to the analysis as they reached 50 years of age. Their alcohol intake was assessed at baseline and updated during follow-up evaluations using a validated semiquantitative food-frequency questionnaire. After separate analyses for women and men, pooled estimates of the relationship of alcohol to the risk of AMD were calculated. RESULTS: Age-related macular degeneration associated with a visual acuity loss of 20/30 or worse, including the early and dry and wet types, was diagnosed in 298 women (from 697498 person-years of follow-up) and 153 men (229 180 person-years) by 1994, the end of follow-up. After controlling for age, smoking, and other risk factors, the pooled relative risks (RRs) and 95% confidence intervals (CIs) for AMD compared with nondrinkers were 1.0 (0.7-1.2) for drinkers who consumed 0.1 to 4.9 g/d of alcohol; 0.9 (0.6-1.4) for 5 to 14.9 g/d; 1.1 (0.7-1.7) for 15 to 29.9 g/d; and 1.3 (0.9-1.8) for 30 g/d or more. Among women, there was a suggestion of a modest increased risk of the disease in drinkers who consumed 30 g/d or more (RR, 1.5; 95% CI, 1.0-2.4); this was limited to an increased risk of the early and dry form (RR, 2.0; 95% CI, 1.2-3.4). No specific type of alcohol provided protection against AMD. CONCLUSION: This prospective study does not support an inverse relationship between moderate alcohol consumption and risk of AMD.

Aged↗

PubMed2000

Proportion of colon cancer risk that might be preventable in a cohort of middle-aged US men.

OBJECTIVE: Diet and lifestyle likely play major roles in colon cancer incidence; however, the proportion of colon cancer risk that might be preventable is unknown. Thus, we estimated the proportion of colon cancer risk among men in the prospective Health Professionals Follow-up Study that might be attributable to a constellation of modifiable risk factors, and thus might be preventable. METHODS: We included 47,927 men aged 40-75 years in 1986, among whom we confirmed 411 colon cancer cases from 1986 to 1996. Risk factors considered were obesity, physical inactivity, alcohol consumption, early adulthood cigarette smoking, red meat consumption, and low intake of folic acid from supplements. We calculated a risk score that was the sum across the six risk factors of the values of 1 (better exposure) to 5 (worse exposure) corresponding to the exposure category. We entered the risk score into a logistic regression model and estimated the population attributable risk percent (PAR%) using the method of Bruzzi et al. RESULTS: After adjusting for age and family history of colorectal cancer and comparing the risk score for the combined six modifiable colon cancer risk factors at or above the approximate 20th, 10th, or 5th percentiles vs. below, the PAR% increased from 39% (95% confidence interval (CI) = 23-58%), to 48% (95% CI = 25-71%), to 55% (95% CI = 27-80%), respectively. Using a second method in which we used cut-points consistent with general-good health behaviors for each risk factor, comparing men with at least one risk factor to men without any risk factors (3.1% of the men), the PAR% was 71% (95% CI = 33-92%). CONCLUSION: The findings from this analysis suggest that, if all the members of this cohort of middle-aged US men had a modifiable exposure distribution comparable to the men with low risk scores, a large proportion of colon cancer risk might be avoidable. Additional study is required to determine whether making changes in these six risk factors now would reduce the risk of colorectal neoplasia, or whether the proportion of colon neoplasia that might be avoidable would be similar in populations with different characteristics.

Adenoma↗

PubMed2000

Glycemic status and soluble tumor necrosis factor receptor levels in relation to plasma leptin concentrations among normal weight and overweight US men.

OBJECTIVE: Leptin, an adipocyte-derived protein product of the obesity (ob) gene, is a multifunctional polypeptide associated with the development of obesity-related disorders in humans. There is considerable inter-individual variation in plasma leptin even among subjects with comparable obesity levels, which suggests that factors other than adipose mass may be involved in the regulation of leptin expression and/or production. The purpose of this study was to evaluate the potential role of glycemic status and adipose-derived cytokines in regulating plasma leptin levels among normal and overweight men. DESIGN: Cross-sectional study. SUBJECTS AND MEASUREMENTS: We measured plasma leptin, insulin, c-peptide and plasma soluble tumor necrosis factor receptor (sTNF-R) concentrations in 178 men. The subjects were selected from the Health Professionals Follow-up Study (HPFS), and aged 47-64 y in 1994, were free of cardiovascular disease, diabetes mellitus, malignant neoplasms, and had provided a fasting blood sample and a detailed lifestyle questionnaire. RESULTS: Men in the highest quintile of plasma leptin (mean = 12.7 ng/ml) weighed more, were less physically active and had higher circulating insulin, c-peptide, sTNF-R1 and sTNF-R2 concentrations than men in the lowest quintile (mean = 2.8 ng/ml). We found a significant correlation between plasma insulin, c-peptide, glycosylated hemoglobin (HbA1c), and sTNF-R1 on leptin concentrations (with Spearman correlation coefficients ranging from 0.17 to 0.48 and all P < 0.05). Only HbA1c and sTNF-R1 were independently and positively associated with plasma leptin after further adjusting for body mass index and other metabolic parameters of interest. Interestingly, these observed associations were limited to men with a BMI > or = 25 kg/m2. CONCLUSION: Our results suggest that glucose homeostasis and the activity of the TNF system may modulate leptin secretion and production among overweight men. Glucose homeostasis and TNF-alpha is important in metabolic disorders related to hyperleptinemia.

Antigens, CD↗

PubMed2000

Vitamin A supplements and diarrheal and respiratory tract infections among children in Dar es Salaam, Tanzania.

OBJECTIVE: To determine the effect of vitamin A supplementation on the risk of diarrhea and of acute respiratory infection. DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: Dar-es-Salaam, Tanzania. SUBJECTS: Six hundred eighty-seven children, 6 to 60 months old, hospitalized with pneumonia, who received vitamin A or placebo at baseline and at 4 and 8 months after discharge from hospital. MAIN OUTCOME VARIABLES: Incidence and duration of episodes of diarrhea and respiratory tract infections during the year after discharge from the hospital. RESULTS: Relative to those receiving placebo, children receiving vitamin A had a significantly smaller risk of severe watery diarrhea (multivariate odds ratio = 0.56, 95% CI = 0.32-0.99, P =.04) but a higher risk of cough and rapid respiratory rate (multivariate odds ratio = 1.67, 95% CI = 1.17-2.36, P =.004). Vitamin A supplementation was also associated with increased risk of acute diarrhea among normally nourished children or children with stunted growth but was relatively protective among children with wasting disease (P value for interaction =.01). The apparently increased risk of respiratory tract infection was limited to children who were seronegative for human immunodeficiency virus (HIV) (P value for interaction =.07). CONCLUSIONS: Vitamin A supplements provide a low-cost intervention against morbidity in HIV-infected and undernourished children. Supplements may also have serious non-lethal adverse outcomes in well-nourished individuals. Whether these apparent detrimental effects of vitamin A are transient or long-term needs to be examined.

Child, Preschool↗