Smad7与肝纤维化

转化生长因子-β1(TGF-β1)在肝纤维化形成过程中具有重要作用.Smad蛋白家族是TGF-β细胞内信号转导的重要分子,其中Smad7能够抑制TGF-β信号转导通路,介导细胞内负反馈,从而阻断TGF-β介导的肝纤维化.此文就Smad7抑制肝纤维化机制作一综述.     

Smads在TGF-β信号转导途径中的致肝纤维化作用

转化生长因子（transforming growthfactor，TGF-β）超家族包括TGF-β1、激活素（activin）、骨形态发生蛋白（bone morphogenetic protein，BMP），Smads为TGF-β蛋白家族重要的胞内效应因子，为目前所知的细胞内唯一的TGF-β受体激酶的底物，能将TGF-β信号由胞膜转入核内，Smads经磷酸化后可转导TGF-β后信号，其作用包括细胞增生、分化及凋亡，TGF-β诱导其膜受体直接与激活的Smad蛋白作用，这种激活的Smad蛋白可调控目的基因的转录。     

SMAD4与消化系肿瘤

近年来，细胞内信号转导已成为普遍关注的生物学问题，细胞内信号转导调节着多细胞生物的生长、发育、分裂及死亡等生物学行为，与肿瘤的发生发展密切相关。有Smads介导的转化生长因子（transforminggrowthfactor-β，TGF-β）通路就是其中的一条。TGF-β是一个庞大的家族，由大量结构相关的多肽生长因子组成，包括原形的TGF、激活素（activin）和骨形态发生蛋白（bonemorphageneticprotein，BMP）等三大类40多个成员，具有广泛的生物学作用，如调节细胞生长分化、基质形成、机体免疫、损伤修复和肿瘤生长等。Smads蛋白直接参与TGF超家族的信号转导。在TGF-β信号转导途径中，Smads蛋白作为TGF-β信号传达因子以辅激活物的形式参与调节已成为众多学者关注的中心。     

TGF-β/Smads信号转导通路与胃癌关系的研究进展

转化生长因子β(TGF-β)是具有多种生物学活性的多肽类细胞因子,参与调节细胞多种生物学功能。TGF-β信号通路具有调控细胞增殖和分化的作用,由Smads蛋白介导的TGF-β信号转导是该通路最经典的转导方式。近年研究表明,TGF-β/Smads信号通路任何环节的功能障碍均有可能导致该信号转导异常,从而影响胃癌的发生、发展。本文就TGF-β/Smads信号转导通路与胃癌的关系作一综述。     

Smads蛋白在TGF-β1/Smads通路介导上皮间质转化中的作用

上皮间质转化(epithelialmesenchymal transition,EMT)是一个动态的、可逆的过程,可以促进组织发育、伤口愈合以及恶性上皮肿瘤发生、侵袭和转移,已成为当前研究的热点.Smads蛋白作为细胞内重要的信号转导蛋白,直接参与转化生长因子-β1(transforming growth factorβ1,TGF-β1)超家族中许多成员的信号转导,发挥调节细胞增殖、分化、迁移、凋亡等多种生物学活动.随着对Smads蛋白结构与功能的不断认识,日渐发现由Smads参与的TGF-β1/Smads通路所介导的EMT与人类的某些疾病(器官组织纤维化、肥厚性疤痕以及癌症等)密切相关.本文简要综述了Smads蛋白在TGF-β1/Smads通路介导EMT中的作用,以期对Smads参与调控EMT有更进一步的认识.     

抑癌基因Smad4与胃肠道肿瘤

Smad4是一种肿瘤抑制基因,其编码的蛋白是转化生长因子-β(TGF-β)超家族细胞内信号转导和调节的中心分子。Smad4突变失活引起的TGF-β信号转导紊乱,导致肿瘤细胞对TGF-β的生长抑制作用逃逸,与胃肠道肿瘤的发生发展存在一定关系。突变的Smad4蛋白较野生型更易被泛素介导的蛋白酶体降解。     

特发性肺纤维化中Smurf2对TGF-β1/Smad通路调控机制

特发性肺纤维化是肺间质纤维化的主要原因,为最常见的间质性肺疾病.其主要病理特点为大量成纤维细胞、肌成纤维细胞集聚、增殖.近年来研究表明转化生长因子β1(transforming growth factor-β1,TGF-β1)在肺纤维化的形成与发展中起关键性作用.Smad蛋白是参与TGF-β1信号细胞内传导的一类信号蛋白,是TGF-β1信号传导重要通路.近年来发现Smad泛素调节因子2(Smad ubiquitination regulatory factor 2,Smurf2)可选择性作用于Smad蛋白,进而调控TGF-β信号传导.本文就特发性肺纤维化中Smurf2对TGF-β1/Smad通路的调控机制作一综述.     

TGF-β及Smad与肝纤维化

转化生长因子β(transforming growth factor beta．TGF-β)是致肝纤维化(hepatic fibrosis)最重要的细胞因子，具有多种生物学功能，Smad蛋白参与TGF-β细胞内信号转导。本综述近年国外在TGF-β跨膜信号转导及其与肝纤维化关系的研究进展，介绍TGF-β与Smad的结构、生物学活性、信号转导方式，两与肝纤维化形成机制及相应的治疗进展。     

转化生长因子-β与Smad 7在肾脏疾病中的作用

转化生长因子β(TGF-β)是多功能细胞因子,具有调节细胞分裂、炎症反应,以及促进细胞外基质沉积等多种作用。Smad 7蛋白是近年来被认识的TGF-β1细胞内信号转导的负调控蛋白,能自动反馈调节TGF-β1对靶基因的转录。本文着重介绍TGF-β与Smad 7在肾脏疾病中所起的作用以及尚需解决的问题作一简要综述。     

TGF-β/smad信号通路在糖尿病肾病中的作用

转化生长因子-β(TGF-β)在糖尿病肾病发病中起重要作用。近年来研究发现丝/苏氨酸激酶受体(smad)蛋白在丝/苏氨酸型受体的信号转导中起重要作用。TGF-β与膜上特异受体结合后,经smad蛋白转导至核内,调节基因的转录。TGF-β/smad信号通路可通过介导足细胞损伤、系膜细胞增生、基底膜增厚、上皮细胞间充质转化、肾细胞凋亡最终导致肾小球硬化及肾间质纤维化。对TGF-β/smad信号通路的研究为防治糖尿病肾病提供了一个新思路。     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Presence of immunoreactive growth hormone and prolactin in the ovine pineal gland

Abstract: The use of antisera raised against bovine growth hormone (GH) and ovine prolactin (PRL) enabled the detection of related immunoreactive (ir) sequences of proteins in ovine pineal tissue. The isolation of PRL-like ir-material was accomplished using a 0.25 M ammonium sulphate (pH 5.5) extraction followed by ethanol precipitation, whereas the resulting 2.0 M ammonium sulphate (pH 7.0) precipitate contained a GH-like immunoreactivity. Gel chromatography of the GH-like immunoreactivity (Sephadex G-100) indicated the presence of several GH-like fragments ranging in the M_r range of 7,000 to 55,000. Analyses of the PRL-like ir-material found in pineal tissue on HPLC using a TSK 545-DEAE column led to the resolution into a single peak of immunoreactivity. A single peak of activity was also observed following chromatofocusing and hydrophobic interaction chromatography of the ir-peak from the TSK 545-DEAE column. The PRL-like ir-material inhibited the binding of [¹²⁵I]ovine PRL-S14 to anti-ovine PRL antibodies without showing an affinity for binding to anti-rat PRL or anti-bovine GH antibodies. Scatchard analysis of the binding of pineal PRL-like ir-material and pituitary ovine PRL-S14 to liver membranes from day-20 pregnant rats revealed similar affinity constants (K_a of 4.7 ± 0.2 × 10⁹ M^-1). In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL-like ir-material, an effect known to be specific for lactogenic hormones. The pineal PRL-like immunoreactivity appeared on sodium dodecyl sulfate polyacrylamide gels as a single major band of M_r 24,000. The functional status of PRL-and GH-like ir-material in the ovine pineal remains to be determined, but evidence is presented that the overall protein synthesis rate of the rat pineal responded to circulating concentrations of PRL.     

N-acetyl-L-cysteine combined with mesalamine in the treatment of ulcerative colitis： Randomized,placebo-controlled pilot study

AIM： To evaluate the effectiveness and safety of oral N-acetyl-L-cysteine （NAC） co-administration with mesalamine in ulcerative colitis （UC） patients.
METHODS： Thirty seven patients with mild to moderate UC were randomized to receive a four-wk course of oral mesalamine （2.4 g/d） plus N-acetyl-L-cysteine （0.8 g/d） （group A） or mesalamine plus placebo （group B）. Patients were monitored using the Modified Truelove-Witts Severity Index （MTWSI）. The primary endpoint was clinical remission （MTWSI ≤ 2） at 4 wk. Secondary endpoints were clinical response （defined as a reduction from baseline in the MTWSI of ≥ 2 points） and drug safety. The serum TNF-α, interleukin-6, interleukin-8 and MCP-1 were evaluated at baseline and at 4 wk of treatment. RESULTS： Analysis per-protocol criteria showed clinical remission rates of 63% and 50% after 4 wk treatment with mesalamine plus N-acetyl-L-cysteine （group A） and mesalamine plus placebo （group B） respectively （OR = 1.71; 95% CI： 0.46 to 6.36; P = 0.19; NNT = 7.7）. Analysis of variance （ANOVA） of data indicated a significant reduction of MTWSI in group A （P = 0.046） with respect to basal condition without significant changes in the group B （P = 0.735） during treatment. Clinical responses were 66% （group A） vs 44% （group B） after 4 wk of treatment （OR = 2.5; 95% CI： 0.64 to 9.65; P = 0.11; NNT = 4.5）. Clinical improvement in group A correlated with a decrease of IL-8 and MCP-1. Rates of adverse events did not differ significantly between both groups.
CONCLUSION： In group A （oral NAC combined with mesalamine） contrarily to group B （mesalamine alone）, the clinical improvement correlates with a decrease of chemokines such as MCP-1 and IL-8. NAC addition not produced any side effects.     

Delorme's transrectal excision for internal rectal prolapse

Surgical therapy of functional outlet obstruction in patients with internal rectal intussusception may include abdominal, perineal, or transrectal procedures. Because abdominal procedures often result in significant physiologic impact but unrelieved constipation, the authors have elected Delorme's transrectal excision for management of these patients. Since a short-term placebo effect attends many therapies, this report describes results of transrectal excision only after a threeyear postoperative period. Delorme's transrectal excision of internal intussusception accomplished sustained symptomatic relief in over 70 percent of otherwise refractory constipated patients. The association of internal intussusception with other abnormalities underscores the importance of defining both anatomic and functional components when selecting patients whose constipation may require surgical therapy. Critical technical elements, surgical pitfalls, and potential complications of the procedure are discussed.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, Toronto, Canada, June 11 to 16, 1989.     

The oral glucose tolerance test: A comparison of the time points on the basis of limit values,normal dispersion,and reproducibility

Summary Time points in the glucose tolerance test (GTT) are compared on the basis of limit values, dispersion within a reference population, and reproducibility. We suggest using the distance between a limit value and the median reference value as a measure of the magnitude of abnormality. The distance between 140 mg/100 ml and the median fasting plasma glucose value is chosen as a standard distance and limits for other points in the GTT are calculated to equal this standard distance of abnormality. We suggest that the probability of correctly interpreting an inividual result is directly related to the reproducibility of the test and inversely related to the percentage of the total range of values which is dispersed among the normal population. The ratio of reproducibility to percentage normal dispersion is proposed as an index of the probability of correctly interpreting an individual result. According to this index, the probability of correct interpretation varies in order: fasting plasma glucose concentration>3-h>2-h>0.5-h>1-h plasma glucose concentration.