No abstract

Increased intake of selenium (Se) may reduce the risk of degenerative diseases including cancer but excessive intake may be toxic. Wheat is a major source of dietary Se in humans. However, the effect of Se from wheat that is agronomically biofortified with Se on biomarkers of human health status is unknown. This study aimed to investigate whether improving Se status, by increased dietary intake of Se‐biofortified wheat, affects biomarkers of cancer risk, cardiovascular disease risk, oxidative stress, and immune function in healthy South Australian men. A 24‐week placebo‐controlled double‐blind intervention was performed in healthy older men (n = 62), with increased dose of Se intake every 8 weeks. Wheat was provided as 1, 2, and 3 puffed wheat biscuits, during weeks 1–8, 9–16, and 17–24, respectively. Blood was collected to measure a wide range of disease risk biomarkers. Consumption of Se‐biofortified wheat was found to increase plasma Se concentration from a baseline level of 122 to 192 μg/L following intake of three biscuits/day, which provided 267 μg Se. Platelet glutathione peroxidase, chromosome aberrations, and DNA damage in lymphocytes measured using the cytokinesis‐block micronucleus cytome assay and with the Comet assay, plasma F2‐isoprostanes, protein carbonyls, plasma C‐reactive protein, and leukocyte number were unaffected by the improved Se status. Improvement of Se status by consumption of Se‐biofortified wheat did not substantially modify the selected biomarkers of degenerative disease risk and health status in this apparently selenium‐replete cohort of healthy older men in South Australia. Environ. Mol. Mutagen. 2009. © 2009 Wiley‐Liss, Inc.

Mutations in BRCA1 and BRCA2 genes may cause defective DNA repair and increase the risk for breast cancer. Folate deficiency is associated with increased breast cancer risk and induces chromosome abnormalities. We hypothesized that BRCA1 and BRCA2 germline mutation carriers are more sensitive to the genome damaging effect of folate deficiency compared with healthy non-carrier controls and that this sensitivity is further increased in those carriers who develop breast cancer. We tested these hypotheses in lymphocytes cultured in a medium containing 12 or 120 nM folic acid (FA) for 9 days and measured proliferative capacity and chromosomal instability using the cytokinesis-block micronucleus assay. BRCA1 and BRCA2 mutation carriers with or without breast cancer were not abnormally sensitive to FA deficiency-induced chromosome instability; however, BRCA2 mutation carriers had significantly reduced cell proliferation. FA deficiency reduced cell proliferation and increased micronucleus formation significantly, accounting for 45-59% and 70-75% of the variance in these parameters compared with 0.3-8.5% and 0.2-0.3% contributed by BRCA1 or BRCA2 mutation carrier status, respectively. The results of this study suggest that moderate folate deficiency has a stronger effect on chromosomal instability than BRCA1 or BRCA2 mutations found in breast cancer families.

We report on surface-engineered microarrays that provide in situ cell sorting, localization, and immobilization of various subsets of human primary lymphocytes, followed by an on-chip bioassay for ionizing-radiation-induced cytogenetic damage. The microarray format eliminates the necessity of separating cell sub-populations by alternative means (such as fluorescence- or magnetic-activated cell sorting) prior to performing informational bioassays. To exemplify the potential of this on-chip cytometry approach, we have integrated the cytokinesis-block micronucleus cytome (CBMNcyt) assay with the microarray platform for analysis of the chromosome damage profile of specific subsets of human peripheral lymphocytes. Microarray results were compared with data obtained from the traditional CBMNcyt assay on heterogeneous lymphocyte populations, and with flow cytometry data. Our results suggest that cytogenetic damage caused by ionizing radiation is not uniformly distributed across all lymphocytes subsets, but rather concentrated in specific subsets. The salient features of our approach are that it requires very small volumes of reagents, allows sorting of lymphocyte subsets in situ, increases parallelism of cell assays and is amenable to high content microscopy analysis. The on-chip cytometry format opens new vistas for advanced cell-based assays, potentially bringing to light important information which remains hidden with conventional assays and hence engendering new discoveries in cell biology.