The micronucleus (MN) assay in exfoliated buccal cells is a useful and minimally invasive method for monitoring genetic damage in humans. This overview has concluded that although MN assay in buccal cells has been used since the 1980s to demonstrate cytogenetic effects of environmental and occupational exposures, lifestyle factors, dietary deficiencies, and different diseases, important knowledge gaps remain about the characteristics of micronuclei and other nuclear abnormalities, the basic biology explaining the appearance of various cell types in buccal mucosa samples and effects of diverse staining procedures and scoring criteria in laboratories around the world. To address these uncertainties, the human micronucleus project (HUMN; see http://www.humn.org) has initiated a new international validation project for the buccal cell MN assay similar to that previously performed using human lymphocytes. Future research should explore sources of variability in the assay (e.g. between laboratories and scorers, as well as inter- and intra-individual differences in subjects), and resolve key technical issues, such as the method of buccal cell staining, optimal criteria for classification of normal and degenerated cells and for scoring micronuclei and other abnormalities. The harmonization and standardization of the buccal MN assay will allow more reliable comparison of the data among human populations and laboratories, evaluation of the assay's performance, and consolidation of its world-wide use for biomonitoring of DNA damage.

The micronucleus assay in human buccal cells as a tool for biomonitoring DNA damage: The HUMN project perspective on current status and knowledge gaps

Update on human health effects of boron.

Evidence from numerous laboratories using a variety of experimental models, including humans, shows that boron is a bioactive beneficial element. Much evidence has come from studies that did not require nutritional or environmental stressors or fastidious methods in diet preparation or environmental control. The evidence includes deprivation studies showing that boron is necessary for some higher animals to complete the life cycle, and that realistic low boron intakes result in impaired bone health, brain function, and immune response. Thus, low boron intake is a relevant nutritional concern, which diets rich in fruits, vegetables, nuts, and pulses can prevent.

Is boron nutritionally relevant

Objectives Micronucleus (MN) assay in buccal exfoliated cells is a minimally invasive method for monitoring genetic damage in human populations. Statistical and epidemiological issues related to the design and analysis of studies based on this biomarker are addressed. Methods A systematic review of recent literature on the buccal MN assay has been carried out to provide a state-of-the-art evaluation of how critical topics such as control for confounding, sample size and statistical power, number of cells scored, endpoint selection, and statistical modelling, are considered. In addition, a meta-analysis has been performed to estimate the impact of most common confounders on MN frequency, and to provide a baseline value of MN frequency in the control population. Results A total number of 63 eligible studies were included in the analysis. Age (98.4%), gender (85.7%), and smoking habit (90.5%) were the most commonly studied confounders. Univariate statistics were estimated in most studies while multivariate analysis was applied only in the 47.6%. Baseline MN frequency in controls was 1.10/1000 cells (95% confidence interval 0.70–1.72), and the relative increment in subjects exposed to genotoxic agents or affected by disease correlated with similar observations in lymphocytes ( R 2  = 0.74). A minimum number of 4000 cells is recommended to reduce the variability of the MN mean estimates, in contrast with the current practice of scoring only 2000 cells (81% of studies). Poisson or Negative Binomial are the preferred statistical models when more than 2000 cells are scored. Studies scoring smaller numbers of cells should consider the use of statistical models taking into account the excess of zeros, e.g., the Zero Inflated Poisson (ZIP) models. Conclusions The quality of papers published on the buccal MN assay can be substantially improved, with better consideration of basic issues such as power analysis, control for confounding, choice of the statistical model, and the number of cells to be scored.

Human population studies with the exfoliated buccal micronucleus assay: Statistical and epidemiological issues

The trace mineral boron is a micronutrient with diverse and vitally important roles in metabolism that render it necessary for plant, animal, and human health, and as recent research suggests, possibly for the evolution of life on Earth. As the current article shows, boron has been proven to be an important trace mineral because it (1) is essential for the growth and maintenance of bone; (2) greatly improves wound healing; (3) beneficially impacts the body's use of estrogen, testosterone, and vitamin D; (4) boosts magnesium absorption; (5) reduces levels of inflammatory biomarkers, such as high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor α (TNF-α); (6) raises levels of antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase; (7) protects against pesticide-induced oxidative stress and heavy-metal toxicity; (8) improves the brains electrical activity, cognitive performance, and short-term memory for elders; (9) influences the formation and activity of key biomolecules, such as S-adenosyl methionine (SAM-e) and nicotinamide adenine dinucleotide (NAD(+)); (10) has demonstrated preventive and therapeutic effects in a number of cancers, such as prostate, cervical, and lung cancers, and multiple and non-Hodgkin's lymphoma; and (11) may help ameliorate the adverse effects of traditional chemotherapeutic agents. In none of the numerous studies conducted to date, however, do boron's beneficial effects appear at intakes > 3 mg/d. No estimated average requirements (EARs) or dietary reference intakes (DRIs) have been set for boron-only an upper intake level (UL) of 20 mg/d for individuals aged ≥ 18 y. The absence of studies showing harm in conjunction with the substantial number of articles showing benefits support the consideration of boron supplementation of 3 mg/d for any individual who is consuming a diet lacking in fruits and vegetables or who is at risk for or has osteopenia; osteoporosis; osteoarthritis (OA); or breast, prostate, or lung cancer.

Nothing Boring About Boron.

Recent evidence indicates that boron and borates may have anticarcinogenic properties. In this study, we have investigated the incidence of adverse cytological findings in cervical smears and the micronucleus (MN) frequency in women living in boron-rich and boron-poor regions. Cervical smears were prepared from 1059 women with low socioeconomic status; 472 of the women lived in relatively boron-rich rural areas, while 587 lived in relatively boron-poor regions. The average and standard deviation values for the age of the women screened with the cervical Pap smear test were 41.55 +/- 8.38. The mean dietary intake of boron was 8.41 mg/day for women from the boron-rich regions, and 1.26 mg/day for women living in the boron-poor regions (P 0.05). Also, there were no significant correlations between age and MN frequency for women from both the boron-rich (r = 0.133, P = 0.48, P > 0.05) and boron-poor (r = -0.033, P = 0.861, P > 0.05) regions. The results suggest that ingestion of boron in the drinking water decreases the incidence of cervical cancer-related histopathological findings. There was no correlation between the pathological findings from the cervical smears and buccal cell MN frequency suggesting that the two study populations were exposed equally to gentotoxic agents. Nonetheless, cervical cancer-related histopathological findings should be validated by other researchers.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/tox.20229

Engin Uzgören

Papers

Effects of dietary boron on cervical cytopathology and on micronucleus frequency in exfoliated buccal cells.