1.
Sex-Specific Associations between One-Carbon Metabolism Indices and Posttranslational Histone Modifications in Arsenic-Exposed Bangladeshi Adults.
Howe, CG, Liu, X, Hall, MN, Ilievski, V, Caudill, MA, Malysheva, O, Lomax-Luu, AM, Parvez, F, Siddique, AB, Shahriar, H, et al
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2017;(2):261-269
-
-
Free full text
-
Abstract
BACKGROUND Posttranslational histone modifications (PTHMs) are altered by arsenic, an environmental carcinogen. PTHMs are also influenced by nutritional methyl donors involved in one-carbon metabolism (OCM), which may protect against epigenetic dysregulation. METHODS We measured global levels of three PTHMs, which are dysregulated in cancers (H3K36me2, H3K36me3, H3K79me2), in peripheral blood mononuclear cells (PBMC) from 324 participants enrolled in the Folic Acid and Creatine Trial, a randomized trial in arsenic-exposed Bangladeshi adults. Sex-specific associations between several blood OCM indices (folate, vitamin B12, choline, betaine, homocysteine) and PTHMs were examined at baseline using regression models, adjusted for multiple tests by controlling for the false discovery rate (PFDR). We also evaluated the effects of folic acid supplementation (400 μg/d for 12 weeks), compared with placebo, on PTHMs. RESULTS Associations between choline and H3K36me2 and between vitamin B12 and H3K79me2 differed significantly by sex (Pdiff < 0.01 and <0.05, respectively). Among men, plasma choline was positively associated with H3K36me2 (PFDR < 0.05), and among women, plasma vitamin B12 was positively associated with H3K79me2 (PFDR < 0.01). Folic acid supplementation did not alter any of the PTHMs examined (PFDR = 0.80). CONCLUSIONS OCM indices may influence PTHMs in a sex-dependent manner, and folic acid supplementation, at this dose and duration, does not alter PTHMs in PBMCs. IMPACT This is the first study to examine the influences of OCM indices on PTHMs in a population that may have increased susceptibility to cancer development due to widespread exposure to arsenic-contaminated drinking water and a high prevalence of hyperhomocysteinemia. Cancer Epidemiol Biomarkers Prev; 26(2); 261-9. ©2016 AACR.
2.
Assessment of lifetime exposure to trihalomethanes through different routes.
Villanueva, CM, Cantor, KP, Grimalt, JO, Castaño-Vinyals, G, Malats, N, Silverman, D, Tardon, A, Garcia-Closas, R, Serra, C, Carrato, A, et al
Occupational and environmental medicine. 2006;(4):273-7
-
-
Free full text
-
Abstract
OBJECTIVES To evaluate lifetime exposure to trihalomethanes (THM) through ingestion, inhalation, and dermal absorption in a hospital based case-control study of bladder cancer conducted between 1998 and 2001 in five areas of Spain. The study base was comprised of subjects living in the catchment areas of the participating hospitals. METHODS Individual information on water related habits was obtained from personal interviews of 1219 cases and 1271 controls: residential and occupational history, drinking water source at each residence and job, amount of water consumption, frequency and duration of showering, bathing, and swimming pool attendance. THM levels, water source history, and year when chlorination started in study areas were ascertained through measurements in drinking water samples and questionnaires to water companies and local authorities. Estimates of THM levels covered 79% of the subjects' person-years of exposure. RESULTS Current and historical average THM levels in water were correlated. Control subjects reported that drinking water source in the last residence was municipal for 63%, bottled for 22%, private well for 2%, and other sources for 13%. For the time window between age 15 and the time of interview, average residential THM level was 32.2 mug/l. THM exposure through ingestion was 23.7 mug/day on average, and was correlated with the ingestion THM level in the workplace. Overall, 79% usually took showers, 16% usually took baths, and 13% had ever attended a swimming pool. Between 21% and 45% of controls unexposed to THM through ingestion were evaluated as moderately or highly exposed through showering or bathing, and 5-10% were exposed through swimming in pools. CONCLUSION The importance of evaluating different routes is underscored by findings from experimental studies showing substantial differences in THM uptake and internal distribution by route.