A novel Lynch syndrome pedigree bearing germ-line MSH2 missense mutation c.1808A>T (Asp603Val).

We report the first pedigree of Lynch syndrome bearing a germ-line MSH2 missense mutation c.1808A>T (Asp603Val). Until now, this missense mutation, in exon 12 of MSH2, was identified as a variant of unknown significance in the International Society for Gastrointestinal Hereditary Tumours database. In vitro induction mutagenesis experiments indicated that the MSH2 mutant protein (Asp603Val) is easily degraded in embryonic stem cells, albeit there is no clinical information concerning this mutant. Our pedigree includes four patients with Lynch syndrome-associated malignancies and clinically matches the Amsterdam II criteria. The proband, a female, first had an endometrial cancer at the age of 49 and then mantle cell lymphoma, colonic and gastric adenocarcinomas and neuroendocrine carcinoma, successively. Her mother also had Lynch syndrome-associated malignancies, including colonic, uterine and gastric cancers, and her elder son had rectal cancer. In the germline of the proband and her son, an MSH2 missense mutation c.1808A>T was discovered. Immunohistochemical analyses indicated that the expression of the MSH2 protein was decreased in the tumors, such as gastric cancer and neuroendocrine carcinoma, due to the missense mutation c.1808A>T. This study showed that the MSH2 missense mutation c.1808A>T (Asp603Val) is a likely pathogenic mutation and is responsible for typical Lynch syndrome-associated malignancies, including neuroendocrine carcinoma.

Large increase in fracture resistance of stishovite with crack extension less than one micrometer.

The development of strong, tough, and damage-tolerant ceramics requires nano/microstructure design to utilize toughening mechanisms operating at different length scales. The toughening mechanisms so far known are effective in micro-scale, then, they require the crack extension of more than a few micrometers to increase the fracture resistance. Here, we developed a micro-mechanical test method using micro-cantilever beam specimens to determine the very early part of resistance-curve of nanocrystalline SiO2 stishovite, which exhibited fracture-induced amorphization. We revealed that this novel toughening mechanism was effective even at length scale of nanometer due to narrow transformation zone width of a few tens of nanometers and large dilatational strain (from 60 to 95%) associated with the transition of crystal to amorphous state. This testing method will be a powerful tool to search for toughening mechanisms that may operate at nanoscale for attaining both reliability and strength of structural materials.