The diet and gut microflora influence the distribution of enteroendocrine cells in the rat intestine

Several functions of the gut are locally influenced by peptides and biogenic amines released from enteroendocrine cells. The aim of the present study was to assess whether the luminal stimulus of diet or microbial flora or diet-microbial interactions have an influence on the distribution of enteroendocrine cells along the crypt-surface axes of the small and large intestine. The effects of diet and indigenous flora were investigated by comparing the numbers of argyrophil and serotonin immunoreactive cells in the jejunum and colon of germ free and conventional rats fed either a purified diet containing fine ingredients or a commercial diet containing crude fibre of cereal origin. The effects of human flora were analysed in germ-free rats inoculated with human faecal organisms. 1. Feeding the commercial diet reduced the number of argyrophil endocrine cells in the jejunum and serotonin immunoreactive cells in the colon of gern-free animals but increased the serotonin immunoreactive cells in the colon of conventional animals. 2. The rat flora increased the serotonin immunoreactive cells in the colon of animals fed a commercial diet and decreased in those fed a purified diet. 3. Inculation of human flora increased the numbers of serotonin immunoreactive cells both in the jejunum and colon. The results provide evidence that the dietary changes and diet-microbial interactions can affect the regional number of enteroendocrine cells.     

Semenogelin I: a coagulum forming, multifunctional seminal vesicle protein

Human seminal plasma spontaneously coagulates after ejaculation. The major component of this coagulum is semenogelin I, a 52-kDa protein expressed exclusively in the seminal vesicles. Recently, a sperm motility inhibitor has been found to be identical to semenogelin I, suggesting that it may also be a physiological sperm motility inhibitor. The protein is rapidly cleaved after ejaculation by the chymotrypsin-like prostatic protease prostate-specific antigen, resulting in liquefaction of the semen coagulum and the progressive release of motile spermatozoa. Some of the cleavage products of Sg I may also have various biological functions. While the semenogelin I protein is unique to human and higher primates, it has recently been shown to belong to a gene family having a similar gene structure but encoding widely differing proteins. The recently elucidated characteristics of the semenogelin I gene as well as the biochemical and functional properties of the encoded protein are reviewed, and an attempt is made to integrate the various findings into a model for semen coagulation, sperm immobilization and potential other functions. Received 21 October 1998; received after revision 15 December 1998; accepted 15 December 1998     

<Emphasis Type="Italic">Drosophila melanogaster</Emphasis> innate immunity: an emerging role for peptidoglycan recognition proteins in bacteria detection

Over the past years, parallel studies conducted in mammals and flies have emphasized the existence of common mechanisms regulating the vertebrate and invertebrate innate immune systems. This culminated in the discovery of the central role of the Toll pathway in Drosophila immunity and in the implication of Toll-like receptors (TLRs)/interleukin-1(IL-1) in the mammalian innate immune response. In spite of clear similarities, such as shared intracellular pathway components, important divergences are expected between the two groups, whose last common ancestor lived more than half a billion years ago. The most obvious discrepancies lie in the mode of activation of the signalling receptors by microorganisms. In mammals, TLRs are part of protein complexes which directly recognize microbe-associated patterns, whereas Drosophila Toll functions like a classical cytokine receptor rather than a pattern recognition receptor. Recent studies demonstrate that members of the evolutionarily conserved peptidoglycan recognition protein family play an essential role in microbial sensing during immune response of Drosophila.Received 26 June 2003; received after revision 29 July 2003; accepted 25 August 2003     

全效利用乳酪蛋白制备CPPs与CNPPs研究进展

综述了国内外酪蛋白源生物活性肽产品的开发研究进展,综合国内外市场酪蛋白磷酸肽(CPPs)开发现状,提出了开发CPPs的同时充分利用酪蛋白非磷酸肽(CNPPs),在工业化规模上全面利用酪蛋白资源生产生物活性肽的建议.     

AVP对VSMC脂质过氧化的影响及CGRP、SP的调节作用

目的：研究AVP对VSMC脂质过氧化的影响及CGRP、SP的调节作用。方法：以培养的大鼠血管平滑肌细胞（VSMC）为模型,动态观察了精氨酸加压素（AVP）对VSMC脂质过氧化的影响,及降钙素基因相关肽（CGRP）、P物质（SP）对AVP作用的调节,旨在探讨它们在高血压病发病中的意义。结果：（1）10－7M的AVP作用后,VSMP的丙二醛（MDA）含量明显高于对照组（P＜0．01）;（2）10－7M的CGRP、SP分别与10－7M的AVP共同作用后,VSMP的MDA含量均减少,与AVP对照组比较,差异非常显著（P＜0．01）。结论：AVP参与高血压病的发病与其致VSMC的脂质过氧化损伤有关,CGRP、SP对其有拮抗作用。     

家蚕抗菌肽的一些性质及抗肿瘤活性

由Ｅ．ｃｏｌｉＫ１２Ｄ３１诱导的家蚕血淋巴中提取的抗菌肽对热稳定，高温高压处理３０分钟仍保持原有活性。抗菌肽对木瓜蛋白酶不敏感，对蛋白酶Ｅ较敏感，而对蛋白酶Ｋ和胰蛋白酶则极为敏感，抗菌肽对ＰＨ的变化较为稳定，在ＰＨ２．２－８．０的范围内活性基本不变，肿瘤模型实验观察到免疫血淋巴对宫颈瘤有明显的抑瘤作用。抗菌肽与Ｋ５６２人髓样白血病细胞混合培育一定时间后，电镜观察可看到细胞膜和细胞器发生明显变化，最     

海洋活性肽研究的回顾与展望

海洋环境资源丰富,物种多样,是活性肽开发与研究的巨大宝库。本文分析了活性肽丰富的海洋来源及生物功用,并且对活性肽的自然来源途径和人工合成来源途径进行了论述,包括活性肽的分离、纯化、合成、筛选等方面,并强调了海洋活性肽在食品工业、医药学、畜牧业、水产养殖业、尤其是在环境保护中的应用现状与潜力,还从多角度、多层面对海洋活性肽的研究作出展望．     

The endocrine role for chromogranin A: A prohormone for peptides with regulatory properties

Chromogranin A (CgA) belongs to the granin family of uniquely acidic secretory proteins co-stored and co-secreted with other hormones and peptides in elements of the diffuse neuroendocrine system. The granins arise from different genes and are characterized by numerous sites for post-translational cleavage into shorter peptides with postulated regulatory properties. This review is directed towards endocrine aspects of CgA and its biologically active peptides. There is ample evidence from in vitro studies of distinct effects and targets for three CgA-derived peptides, vasostatin-I, pancreastatin and catestatin. Endocrine regulations are indicated from in vivo studies, consistent with the postulated prohormone function of CgA for peptides with regulatory properties. Most of the effects fit into patterns of direct or indirect, inhibitory modulations of major functions, implicating CgA peptides in regulation of calcium and glucose metabolism, cardiovascular functions, gastrointestinal motility and nociception, tissue repair, inflammatory responses and as host defense peptides in the first phase of microbial invasions. Received 1 June 2007; received after revision 11 July 2007; accepted 12 July 2007     

The molecular link between β- and γ-secretase activity on the amyloid β precursor protein

Alzheimer’s disease (AD) is characterized by an accumulation in the brain of amyloid β peptides (Aβ). The production of Aβ requires two sequential cleavages induced by β- and γ-secretases on the β-amyloid precursor protein (APP). Altered activity of these secretases is involved in the pathogenesis of AD. The expression and activity of β-secretase (BACE1) is augmented in the brain in late-onset sporadic AD. Mutant presenilin 1 (PS1), the major genetic defect of early-onset familial AD (FAD), alters the activity of γ-secretase, leading to increased production of Aβ42. Here we review the role of oxidative stress as a molecular link between the β- and the γ-secretase activities, and provide a mechanistic explanation of the pathogenesis of sporadic late-onset AD. We also discuss evidence for a role of the same mechanism in the pathogenesis of familial AD carrying PS1 mutations.