Low-level mercury exposure and peripheral nerve function.

BACKGROUND: Mercury is known to be neurotoxic at high levels. There have been few studies of potential peripheral neurotoxicity among persons with exposure to elemental mercury at or near background levels. OBJECTIVES: The present study sought to examine the association between urinary mercury concentration and peripheral nerve function as assessed by sensory nerve conduction studies in a large group of dental professionals. METHODS: From 1997 through 2006 urine mercury measurements and sensory nerve conduction of the median and ulnar nerves in the dominant hand were performed, and questionnaires were completed, on the same day in a convenience sample of dental professionals who attended annual conventions of the American Dental Association. Linear regression models, including repeated measures models, were used to assess the association of urine mercury with measured nerve function. RESULTS: 3594 observations from 2656 subjects were available for analyses. Urine mercury levels in our study population were higher than, but substantially overlap with, the general population. The only stable significant positive association involved median (not ulnar) sensory peak latency, and only for the model that was based on initial observations and exclusion of subjects with imputed BMI. The present study found no significant association between median or ulnar amplitudes and urine mercury concentration. CONCLUSIONS: At levels of urine mercury that overlap with the general population we found no consistent effect of urine mercury concentration on objectively measured sensory nerve function.

Prevalence and correlates of vitamin and supplement usage among men with a family history of prostate cancer.

HYPOTHESES: Men who have a brother with prostate cancer have a 2-fold increased risk of being diagnosed with prostate cancer. Strategies employed by these men to reduce prostate cancer risk are not well understood. Preliminary studies have shown that men with a family history of prostate cancer have a high rate of vitamin and supplement usage aimed at the prevention of prostate cancer. STUDY DESIGN: The authors analyzed data from a cross-sectional study of men with familial and hereditary prostate cancer and their unaffected brothers. A total of 542 unaffected men who had at least one brother who had been diagnosed with prostate cancer regarding their use of vitamins and supplements, as well as the motivation for use, were interviewed. METHODS: The associations between subject characteristics and vitamin and supplement use were evaluated using an unconditional logistic regression modeling approach. RESULTS: Overall, 59.2% and 36.5% of men reported ever using and currently using, respectively, one or more vitamins or supplements (including multivitamins). One third of men took a vitamin or supplement that has been targeted for prostate health or cancer prevention, including green tea, magnesium, male hormones, saw palmetto, selenium, soy, vitamins A, C, E, and zinc. Increasing age at time of survey was associated with vitamin/supplement use (odds ratio [OR] = 1.03; 95% confidence interval [CI] = 1.01-1.05). After adjusting for age at time of survey, being younger than an affected brother was associated with vitamin and supplement use (OR = 1.51; 95% CI = 1.01-2.25). A total of 25% of men reported obtaining information from books or articles as the most common source of information. CONCLUSIONS: The findings indicate that men at an increased risk for prostate cancer report a high rate of vitamin and supplement use, including supplements targeted for prostate cancer prevention. Men with a family history of prostate cancer represent a target population for future chemopreventative agents.

A systematic review of replication studies of prostate cancer susceptibility genetic variants in high-risk men originally identified from genome-wide association studies.

BACKGROUND: Several prostate cancer genome-wide association studies (GWAS) have identified risk-associated genetic variants primarily in populations of European descent. Less is known about the association of these variants in high-risk populations, including men of African descent and men with a family history of prostate cancer. This article provides a detailed review of published studies of prostate cancer-associated genetic variants originally identified in GWAS and replicated in high-risk populations. METHODS: Articles replicating GWAS findings (National Human Genome Research Institute GWAS database) were identified by searching PubMed and relevant data were extracted. RESULTS: Eleven replication studies were eligible for inclusion in this review. Of more than 30 single-nucleotide polymorphisms (SNP) identified in prostate cancer GWAS, 19 SNPs (63%) were replicated in men of African descent and 10 SNPs (33%) were replicated in men with familial and/or hereditary prostate cancer (FPC/HPC). The majority of SNPs were located at the 8q24 region with modest effect sizes (OR 1.11-2.63 in African American men and OR 1.3-2.51 in men with FPC). All replicated SNPs at 8q24 among men of African descent were within or near regions 2 and 3. CONCLUSIONS: This systematic review revealed several GWAS markers with replicated associations with prostate cancer in men of African descent and men with FPC/HPC. The 8q24 region continues to be the most implicated in prostate cancer risk. These replication data support ongoing study of clinical utility and potential function of these prostate cancer-associated variants in high-risk men. IMPACT: The replicated SNPs presented in this review hold promise for personalizing risk assessment for prostate cancer for high-risk men upon further study.