Human Health Risk Assessment For Arsenic: A Critical Review

Millions of people are exposed to arsenic resulting in a range of health implications.This paper provides an up-to-date review of the different sources of arsenic (water, soil and food), indicators of human exposure (biomarker assessment of hair, nail, urine and blood), epidemiological and toxicological studies on carcinogenic and non-carcinogenic health outcomes, and risk assessment approaches. The review demonstrates a need for more work evaluating the risks of different arsenic species such as; arsenate, arsenite monomethylarsonic acid, monomethylarsonous acid, dimethylarsinic acid and dimethylarsinous acid as well as a need to better integrate the different exposure sources in risk assessments

Electronic structures and mechanical properties of boron and boron-rich crystals (Part 2)

The second part of this review treats the phase diagram of boron, because of the importance of the material research. A comparison of the phase stabilities of related crystals has been made and deducing general trends among them has been attempted, from which the reader could get useful insights for future development of superhard materials. The mechanical properties of boron and boron-rich crystals are then discussed as the basis of superhard materials. This area is the primary source, from which many controversies arose regarding the strong intericosahedral bonding. Through working on many examples for deformation, consistent interpretations are given.У другій частині огляду розглянуто фазову діаграму бору. Порівняно фазову стабільність кристалів і зроблено спробу вивести загальні тенденції, які б дозволили отримати уявлення про майбутнє надтвердих матеріалів. Розглянуто механічні властивості бору і кристалів з високим вмістом бору як основи надтвердих матеріалів. Ця область є головним джерелом багатьох суперечностей стосовно сильного міжікосаедричного зв’язку. На основі вивчення багаточисельних прикладів деформації дано логічні трактовки зв’язку.Во второй части обзора рассматрена фазовая диаграмма бора. Сравнена фазовая стабильность кристаллов и сделана попытка вывести общие тенденции, которые позволили бы получить представление о будущем сверхтвердых материалов. Рассмотрены механические свойства бора и кристаллов с высоким содержанием бора как основы сверхтвердых материалов. Эта область исследований является основным источником многих разногласий относительно прочной межикосаэдрической связи. На основании изучения многочисленных примеров деформации даны логические трактовки связи

Screening in silico predicted remotely acting NF1gene regulatory elements for mutations in patients with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1), a neuroectodermal disorder, is caused by germline mutations in the NF1 gene. NF1 affects approximately 1/3,000 individuals worldwide, with about 50% of cases representing de novo mutations. Although the NF1 gene was identified in 1990, the underlying gene mutations still remain undetected in a small but obdurate minority of NF1 patients. We postulated that in these patients, hitherto undetected pathogenic mutations might occur in regulatory elements far upstream of the NF1 gene. In an attempt to identify such remotely acting regulatory elements, we reasoned that some of them might reside within DNA sequences that (1) have the potential to interact at distance with the NF1 gene and (2) lie within a histone H3K27ac-enriched region, a characteristic of active enhancers. Combining Hi-C data, obtained by means of the chromosome conformation capture technique, with data on the location and level of histone H3K27ac enrichment upstream of the NF1 gene, we predicted in silico the presence of two remotely acting regulatory regions, located, respectively, approximately 600 kb and approximately 42 kb upstream of the NF1 gene. These regions were then sequenced in 47 NF1 patients in whom no mutations had been found in either the NF1 or SPRED1 gene regions. Five patients were found to harbour DNA sequence variants in the distal H3K27ac-enriched region. Although these variants are of uncertain pathological significance and still remain to be functionally characterized, this approach promises to be of general utility for the detection of mutations underlying other inherited disorders that may be caused by mutations in remotely acting regulatory elements