The association between caffeine intake and testosterone: NHANES 2013-2014.

BACKGROUND: Caffeine is one of the most commonly used psychoactive drugs in the world, and provides many health benefits including alertness, improved memory, and reducing inflammation. Despite these benefits, caffeine has been implicated in a number of adverse health outcomes possibly due to effects within the endocrine system, effects that may contribute to impaired reproductive function and low testosterone in men. Previous studies have investigated associations between caffeine consumption and testosterone levels in men, although the quantity and generalizability of these studies is lacking, and the results between studies are conflicting and inconclusive. METHODS: Using data from a cross-sectional study of 372 adult men in the 2013-2014 NHANES survey cycle, the researchers set out to characterize the association between serum testosterone levels, caffeine, and 14 caffeine metabolites. RESULTS: Multivariable, weighted linear regression revealed a significant inverse association between caffeine and testosterone. Multivariable, linear regression revealed significant, inverse associations between 6 xanthine metabolic products of caffeine and testosterone. Inverse associations were observed between 5-methyluric acid products and testosterone, as well as between 5-acetlyamino-6-amino-3-methyluracil and testosterone. A significant, positive association was observed for 7-methyl xanthine, 3,7-dimethyluric acid, and 7-methyluric acid. Logistic regression models to characterize the association between 2 biologically active metabolites of caffeine (theobromine and theophylline) and odds of low testosterone (< 300 ng/dL) were non-significant. CONCLUSIONS: These findings suggest a potential role for caffeine's contribution to the etiology of low testosterone and biochemical androgen deficiency. Future studies are warranted to corroborate these findings and elucidate biological mechanisms underlying this association.

Racial differences in microRNA and gene expression in hypertensive women.

Systemic arterial hypertension is an important cause of cardiovascular disease morbidity and mortality. African Americans are disproportionately affected by hypertension, in fact the incidence, prevalence, and severity of hypertension is highest among African American (AA) women. Previous data suggests that differential gene expression influences individual susceptibility to selected diseases and we hypothesized that this phenomena may affect health disparities in hypertension. Transcriptional profiling of peripheral blood mononuclear cells from AA or white, normotensive or hypertensive females identified thousands of mRNAs differentially-expressed by race and/or hypertension. Predominant gene expression differences were observed in AA hypertensive females compared to AA normotensives or white hypertensives. Since microRNAs play important roles in regulating gene expression, we profiled global microRNA expression and observed differentially-expressed microRNAs by race and/or hypertension. We identified novel mRNA-microRNA pairs potentially involved in hypertension-related pathways and differently-expressed, including MCL1/miR-20a-5p, APOL3/miR-4763-5p, PLD1/miR-4717-3p, and PLD1/miR-4709-3p. We validated gene expression levels via RT-qPCR and microRNA target validation was performed in primary endothelial cells. Altogether, we identified significant gene expression differences between AA and white female hypertensives and pinpointed novel mRNA-microRNA pairs differentially-expressed by hypertension and race. These differences may contribute to the known disparities in hypertension and may be potential targets for intervention.

The epidemiology of prostate cancer in Jamaica

PURPOSE: Before this study, the highest reported incidence of prostate cancer in the world was thought to be among United States black men. The age adjusted rates in 1992 for United States black and white men were 249 and 182/100,000 respectively. The epidemiology of prostate cancer in Jamaica, a country of 2.5 million people of primarily African descent, was studied and compared with that of white and black Americans. MATERIALS AND METHODS: The study included 1,121 cases of prostate cancer diagnosed from 1989 to 1994. Sources of information included the Jamaican Cancer Registry, government pathology laboratory, hospital and clinic records, and physician office records. Incidence rates were computed using data from the 1991 Jamaican census. Age adjustments were made using the 1970 United States standard population. RESULTS: The average age adjusted incidence of prostate cancer in Kingston, Jamaica was 304/100,000 men. Median patient age at diagnosis was 72 years. More than 80 percent of the cases were pathologically confirmed. Of the patients 30 percent presented with acute urinary retention, 16 percent presented with bone metastases, 15 percent had gross hematuria at the time of diagnosis and an abnormal rectal examination suspicious for cancer was noted in 42 percent. Prostate specific antigen was measured in only 7 percent of cases in 1989 but in 48 percent of cases by 1994. CONCLUSIONS: These data demonstrate that Jamaican men in Kingston have a high incidence of prostate cancer, much higher than even black Americans during a similar period. Furthermore, the cancers are more significant clinically with greater morbidity in Jamaica than in the United States(AU)