Peutz-Jeghers syndrome: clinicopathology and molecular alterations

Peutz-Jeghers syndrome (PJS, OMIM 175200) is an unusual inherited intestinal polyposis syndrome associated with distinct peri-oral blue/black freckling [1–9]. Variable penetrance and clinical heterogeneity make it difficult to determine the exact frequency of PJS [4]. PJS is a cancer predisposition syndrome. Affected individuals are at high risk for intestinal and extra-intestinal cancers. In 1997, linkage studies mapped PJS to chromosome 19p [10, 11], and subsequently a serine/threonine kinase gene defect (LKB1) was noted in a majority of PJS cases [12, 13]. A phenotypically similar syndrome has been produced in an LKB1 mouse knockout model [14–18]. Several PJS kindred without LKB1 mutations have been described, suggesting other PJS loci [19–22]. The management of PJS is complex and evolving. New endoscopic technologies may improve management of intestinal polyposis. Identification of specific genetic mutations and their targets will more accurately assess the clinical course, and help gage the magnitude of cancer risk for affected individuals. Received 20 February 2006; received after revision 5 May 2006; accepted 15 June 2006     

Nodal signals pattern vertebrate embryos

Vertebrate embryonic patterning requires several conserved inductive signals–including Nodal, Bmp, Wnt and Fgf signals. Nodal, which is a member of the transforming growth factor β (TGFβ) superfamily, activates a signal transduction pathway that is similar to that of other TGFβ members. Nodal genes, which have been identified in numerous vertebrate species, are expressed in specific cell types and tissues during embryonic development. Nodal signal transduction has been shown to play a pivotal role in inducing and patterning mesoderm and endoderm, and in regulating neurogenesis and left-right axis asymmetry. Antagonists, which act at different steps in the Nodal signal transduction pathway, have been shown to tightly modulate the inductive activity of Nodal. Received 20 October 2005; received after revision 15 November 2005; accepted 25 November 2005     

Effect of ethanol on toxicity and metabolism of amphetamine in the mouse.

Ethanol, 3 g/kg i.p., did not significantly alter the acute toxicity of amphetamine in the mouse. However, the urinary metabolite pattern was changed, suggesting that ethanol suppressed metabolism of the stimulant during the initial 6 h period. After 24 h, the mouse metabolized the same fraction of a given dose of amphetamine, whether it was given as amphetamine alone or amphetamine mixed with 2,3 or 4 g/kg ethanol.     

植物标签技术

传统的正向遗传学主要用于克隆表型或功能已确定的基因。转座子标签突变体可用随机标签法从带有活性转座子的自交后代中筛选得到,或用定向标签法从杂交一代中筛选得到,即用目的基因的隐性突变统合体与具高度活性转座号的统合体杂交,极大多数的FI个体为正常表型,但其中会有极少量的表现隐性性状的转庄子插入突变体。正向基因标签和克隆法在利用异源和低拷贝数品系时尤其有用。采用反向fCR或热不对称交替PCR（TAIL－PCR）且很容易从单拷贝或低拷贝数品系中获得插入于两侧的基因组序列。TAIL－PCR由三轮连续的半巢式PCR组成,所…     

关于Quarter可层化空间

对第二纲的仿紧Quarter可层化空间进行了研究,证明了这类空间含有σ闭离散的稠密子集. 同时给出了实数集的子集是消去拓扑半群,但是不是Quarter可层化空间.     

Spectrum characteristics and pump wavelengths of Nd3+-doped double-clad fiber

Conclusion The optimum wavelength of Nd³⁺-doped double-clad fiber laser or amplifier made in China is near 830 nm. The efficiency of Nd³⁺-doped double-clad fiber devices pumped by 820-nm laser is low due to ESA. In order to increase the photochemical stability of the outer cladding, the material of the outer cladding must be advanced.