Single base deletion in the vasopressin gene is the cause of diabetes insipidus in Brattleboro rats

In rats with hereditary hypothalamic diabetes insipidus (Brattleboro rats) the gene for the vasopressin precursor lacks a single G residue in the protein-coding region. The mutation gives rise to an open reading frame predicting a hormone precursor having a different C-terminus.     

Vasopressin stimulates formation of coated pits in rat kidney collecting ducts

The water permeability of collecting ducts is greatly increased by the antidiuretic hormone, vasopressin. This permeability increase is associated with the appearance of intramembrane particle (IMP) clusters on the luminal plasma membranes of principal cells of the collecting duct epithelium. IMP aggregates have also been related to an increase in water permeability of two other vasopressin-sensitive epithelia, the amphibian urinary bladder and the amphibian epidermis, and it has been proposed that these specialized membrane domains might represent specific water-permeable membrane patches, induced by the hormone in their respective epithelia. Using a cytochemical probe for membrane cholesterol, filipin, we show here that the membrane patches in rat kidney are selectively devoid of filipin-sterol complexes and that when identified in thin sections, they have a cytoplasmic bristle coat: both of these features are characteristics of coated pits which, in other systems, are involved in receptor-mediated endocytosis. We also show that vasopressin induces the appearance of coated pits on collecting duct luminal membranes in Brattleboro homozygous rats, which have hereditary diabetes insipidus.     

Atrial natriuretic peptide inhibits angiotensin-stimulated proximal tubular sodium and water reabsorption

The discovery that atrial extracts have potent diuretic and natriuretic properties revealed a possible endocrine function of the heart in the regulation of extracellular fluid volume. Since that first report intense research activity has been directed towards determining the mechanism of action of the active atrial natriuretic polypeptides (ANP) found in these extracts. Despite these efforts it remains controversial whether the renal actions of ANP are exerted solely on the process of glomerular filtration or involve additional direct actions on tubular transport. We have investigated the possibility that atrial natriuretic polypeptides may induce natriuresis by suppression of proximal tubular sodium and water reabsorption. Using shrinking split-drop micropuncture combined with simultaneous capillary perfusion in anaesthetized rats we report that 20 nanomolar alpha-rANP (the main component of ANP in rat plasma) added to the peritubular fluid had no direct effect on proximal fluid uptake whereas picomolar angiotensin II had a marked stimulatory action as reported. The stimulatory effect of angiotensin II on fluid reabsorption was inhibited by peritubular ANP at physiological concentrations and abolished by higher concentrations of ANP. Thus at physiological concentrations ANP acts within the kidney to decrease proximal reabsorption by inhibition of angiotensin-stimulated sodium and water transport.     

Circulating angiotensin II and adrenal receptors after nephrectomy

Mineralocorticoid secretion is predominantly controlled by the octapeptide angiotensin II, which exerts trophic actions on the adrenal glomerulosa and acute regulatory effects on aldosterone biosynthesis. The trophic actions include stimulation of angiotensin II receptors and enzymes of the aldosterone biosynthetic pathway, with corresponding enhancement of the aldosterone secretory capacity of the adrenal gland. The positive regulatory action of angiotensin II on its adrenal receptors occurs with elevations of the circulating peptide concentration within the physiological range and probably contributes to the increased sensitivity of the adrenal during sodium deficiency. In this action, angiotensin II differs from other hormones which decrease their target-cell receptors. However, the increase in adrenal angiotensin II receptors following nephrectomy has been interpreted as evidence for a tonic down-regulating effect of angiotensin II on its adrenal receptors. To clarify these conflicting views we evaluated the effects of nephrectomy on adrenal angiotensin II receptors in relation to blood angiotensin II and plasma electrolyte levels. We show here that hyperkalaemia contributes markedly to the post-nephrectomy increase in adrenal angiotensin II receptors, and that circulating angiotensin II levels persist for an unexpectedly long period after nephrectomy, presumably due to tissue generation of the octapeptide.     

Regulation by angiotensin II of its receptors in resistance blood vessels

The sensitivity of blood vessels to the vasoconstrictor effects of the hormone angiotensin II appears to be modulated by the activity of the renin-angiotensin system. Elevation of circulating angiotensin II levels by sodium depletion or renal artery stenosis is associated with a diminished pressor response to infused angiotensin II (refs 1-3). Conversely, the vasocontrictor response to the hormone is enhanced when endogenous angiotensin II levels are reduced by sodium loading or nephrectomy. The mechanisms of these varying effects are not known, but physiological and pharmacological experiments suggest involvement of the vascular smooth receptor for angiotensin II (refs 5-8). Modification of the interaction between angiotensin II and its vascular receptor, resulting in altered responsiveness to the hormone, could occur either via 'prior occupancy' of receptors by elevated levels of endogenous angiotensin II resulting in fewer free receptors available to respond to circulating angiotensin II (ref. 5), or, elevated levels of angiotensin II could result in a decrease in receptor affinity for the hormone or a decrease in total receptor number in the vascular smooth muscle cell. We now report the first direct evidence, by radioligand binding assay, that angiotensin II regulates the number of its own receptors in resistance vasculature.     

AT1-receptor heterodimers show enhanced G-protein activation and altered receptor sequestration

The vasopressor angiotensin II regulates vascular contractility and blood pressure through binding to type 1 angiotensin II receptors (AT1; refs 1, 2). Bradykinin, a vasodepressor, is a functional antagonist of angiotensin II (ref. 3). The two hormone systems are interconnected by the angiotensin-converting enzyme, which releases angiotensin II from its precursor and inactivates the vasodepressor bradykinin. Here we show that the AT1 receptor and the bradykinin (B2) receptor also communicate directly with each other. They form stable heterodimers, causing increased activation of G alpha(q) and G alpha(i) proteins, the two major signalling proteins triggered by AT1. Furthermore, the endocytotic pathway of both receptors changed with heterodimerization. This is the first example of signal enhancement triggered by heterodimerization of two different vasoactive hormone receptors.     

Molecular cloning of the receptor for human antidiuretic hormone.

Antidiuresis, the recovery of water from the lumen of the renal collecting tubule, is regulated by the hypothalamic release of antidiuretic hormone (ADH), which binds to specific receptors on renal collecting tubule cells, stimulates adenylyl cyclase and promotes the cyclic AMP-mediated incorporation of water pores into the luminal surface of these cells. We report here the isolation of the human ADH receptor gene using a genomic expression cloning approach. The gene was used to clone the complementary DNA from a human renal library. The deduced amino-acid sequence of the receptor yields a hydropathy profile characteristic of receptors with seven putative transmembrane regions. This and the comparison with other cloned receptors indicates that the ADH receptor is a member of the superfamily of G-protein-coupled receptors.     

Somatostatin modulates effects of angiotensin II in adrenal glomerulosa zone

The octapeptide angiotensin II is a major regulator of the adrenal glomerulosa zone, acting both as an acute stimulus of aldosterone secretion and as a trophic hormone which increases steroidogenic enzymes and angiotensin II receptors in glomerulosa cells. Angiotensin II also mediates the adrenal effects of altered sodium balance, and is essential for the aldosterone response to sodium restriction. However, the adrenal effects of angiotensin II are attenuated during sodium loading, suggesting that other local or humoral factors modulate its actions on adrenal glomerulosa function. Somatostatin, the somatotropin release inhibiting factor of the hypothalamus, has been shown to inhibit the secretion and action of several pituitary and non-pituitary hormones. Because somatostatin has been found in several non-neural tissues, and seems to act as a local regulator of endocrine function, we have now examined the possibility that it may also modulate the effects of angiotensin II in the adrenal glomerulosa cell. Our studies have shown that low concentrations of somatostatin specificity inhibit the production of angiotensin II-stimulated aldosterone, and that this action is mediated by specific, high-affinity receptors for somatostatin in the zona glomerulosa.     

HLA-D region beta-chain DNA endonuclease fragments differ between HLA-DR identical healthy and insulin-dependent diabetic individuals

The human HLA-D histocompatibility region encodes class II antigens each of which consists of two polypeptide chains (alpha and beta) inserted in the plasma membrane. These molecules are implicated in the regulation of the immune response but several human diseases are also found to be associated with certain HLA-DR antigens. The occurrence of insulin-dependent (type I) diabetes (IDDM) is strongly associated with HLA-DR3 and/or 4 (ref. 5). The class II antigens, however, show a marked genetic polymorphism associated with the beta-chains which seem, from hybridization studies, to be encoded by several genes. We have therefore used the beta-chain cDNA probe, pDR-beta-1 (refs 8, 10) to test whether there are differences in hybridization pattern between DNA from healthy individuals and diabetic patients, after digestion with restriction endonucleases. Among the HLA-DR 4 and 3/4 individuals, the IDDM patients showed an increased frequency of a PstI 18 kilobase (kb) fragment. A BamHI 3.7 kb fragment, frequent among controls (30-40%), was rarely detected in the IDDM patients (0-2%). These differences may be related to susceptibility to develop the disease.     

高糖诱导ADTIQ的生成和多巴胺的代谢失衡

 2 型糖尿病患者比正常人更容易患帕金森病(PD),而新内源性神经毒素1-乙酰基-6, 7-二羟基-1, 2, 3,4-四氢异喹啉(ADTIQ)可能成为2 型糖尿病并发PD 的一个关键因素,ADTIQ 是由丙酮醛与多巴胺反应合成,但是其在多巴胺能神经元中的生成条件,以及在糖尿病情况下ADTIQ 的生成是否影响多巴胺代谢尚不清楚。本研究以SH-SY5Y 细胞为模型,研究ADTIQ 在细胞模型中的生成条件,发现ADTIQ 是在葡萄糖代谢旺盛的条件下,丙酮醛内源性产生与神经元内的多巴胺反应生成。研究揭示,高糖条件下,SH-SY5Y 细胞和2 型糖尿病的大鼠模型中外周多巴胺的质量浓度减少,而与多巴胺合成和转运相关的酪氨酸羟化酶和多巴胺转运体合成增加。可见,高糖能诱导SH-SY5Y 细胞内ADTIQ 的生成和多巴胺代谢的失衡,ADTIQ 的生成可能成为糖尿病并发PD 的关键因素。     

海南汉族高血压人群血管紧张素转换酶基因多态性研究

采用聚合酶链反应(PCR)技术,对海南汉族106例高血压患者和97例汉族正常人的血管紧张素转换酶(ACE)基因插入/缺失(I/D)多态性检测,观察DD,DI,II基因型频率及等位基因频率,并对所有普通PCR定为DD型的样本进行插入特异性PCR检测,以减少误分型率.结果显示:高血压组DD,DI,II基因型频率分别为16.0%,28.3%,55.7%;D及I等位基因频率分别为30.2%,69.8%.正常对照组DD,DI,II基因型频率分别为15.5%,44.3%,40.2%;D及I等位基因频率分别为37.1%,62.8%.两组之间的DD,DI,II基因型频率及D,I等位基因频率均有显著性差异(P<0.05).高血压组与正常对照组比较,体重指数(BMI)、总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)均有显著性差异(P<0.05);高血压组收缩压、舒张压与正常对照组有显著性差异(P<0.05);高血压组和正常对照组的D等位基因频率都比I等位基因频率低;ACE基因I/D多态性与汉族高血压的发病有相关性,是汉族高血压的主要致病基因.     

基于NMR的维吾尔医异常黑胆质型糖尿病代谢组学研究

 研究异常黑胆质型糖尿病患者体内物质代谢变化的规律。采用基于核磁共振(NMR)测定技术对异常黑胆质型糖尿病患者和黑胆质血糖正常者尿液进行检测,使用正交偏最小二乘法判别(Orthogonal Partial Least-Squares Discriminant Analysis, OPLS-DA)分析研究尿液内源性化合物在两组间的差异。结果显示,异常黑胆质型糖尿病患者组尿液中的代谢物发生了明显的变化。其中葡萄糖、牛磺酸和甜菜碱的含量增加,与黑胆质血糖正常组比较差异有统计学意义(P<0.05);同时多种氨基酸、肌酸酐、马尿酸盐、柠檬酸和二甲胺等含量减少,与黑胆质血糖正常组比较差异有统计学意义(P<0.05)。总之,基于NMR的代谢组学技术和标志物信息均显示异常黑胆质型糖尿病患者和黑胆质血糖正常者存在代谢差异,提示体内某些小分子化合物可能正是维吾尔医异常黑胆质型糖尿病的物质基础。     

血管紧张素转换酶基因多态性与糖尿病的相关性研究

为了研究血管紧张素转换酶(ACE)基因的插入(I)/缺失(D)多态性是否与糖尿病(DM)的易感性相关,对108例糖尿病患者和196例正常人进行了ACE基因多态性分析.发现DM患者基因型DD基因型频率为22%,χ2=4.7,P>0.05(其中,Ⅰ型糖尿病患者相应频率为21%,χ2=4.9,P>0.05;Ⅱ型糖尿病患者为23%,χ2=2.1,P>0.05),而对照组DD基因型频率为16%;DM患者D等位基因频率为38%,χ2=0.0048,P>0.05(其中,Ⅰ型糖尿病患者相应频率为34%,χ2=0.62,P>0.05;Ⅱ型糖尿病患者为41%,χ2=0.25,P>0.05),而对照组相应频率分别为38%.糖尿病患者与对照组之间ACE基因I/D多态性频率存在差异,但不显著.这一结果表明ACE基因的多态性与糖尿病的易感性可能无关.     

氨甲酰类氮氧方酸的合成研究

以水为介质,方酸与脲及其衍生物顺利发生脱水缩合,合成了一类方酸单酰胺化合物－氨甲酰类氨氧方酸３。方酸与芳基脲于水中的反应为Ｎ－芳基氮氧方酸的制备提供了一条新途径。     

Angiotensin-converting enzyme 2 protects from severe acute lung failure

Acute respiratory distress syndrome (ARDS), the most severe form of acute lung injury, is a devastating clinical syndrome with a high mortality rate (30-60%) (refs 1-3). Predisposing factors for ARDS are diverse and include sepsis, aspiration, pneumonias and infections with the severe acute respiratory syndrome (SARS) coronavirus. At present, there are no effective drugs for improving the clinical outcome of ARDS. Angiotensin-converting enzyme (ACE) and ACE2 are homologues with different key functions in the renin-angiotensin system. ACE cleaves angiotensin I to generate angiotensin II, whereas ACE2 inactivates angiotensin II and is a negative regulator of the system. ACE2 has also recently been identified as a potential SARS virus receptor and is expressed in lungs. Here we report that ACE2 and the angiotensin II type 2 receptor (AT2) protect mice from severe acute lung injury induced by acid aspiration or sepsis. However, other components of the renin-angiotensin system, including ACE, angiotensin II and the angiotensin II type 1a receptor (AT1a), promote disease pathogenesis, induce lung oedemas and impair lung function. We show that mice deficient for Ace show markedly improved disease, and also that recombinant ACE2 can protect mice from severe acute lung injury. Our data identify a critical function for ACE2 in acute lung injury, pointing to a possible therapy for a syndrome affecting millions of people worldwide every year.     

四周有氧训练影响Ⅱ型糖尿病大鼠免疫因子IL-1Ra、IL-4、IFN-γ等指标的实验研究

目的:探讨4周有氧训练对Ⅱ型糖尿病大鼠免疫应答因子IL-1Ra、IL-4、IFN-γ等指标变化的影响。方法:24只SD大鼠随机分为Ⅱ型糖尿病安静组(A组)、II型糖尿病有氧训练组(B组),健康安静对照组(C组)。B组进行4周的跑台有氧训练(每周6d),第1周前3d训练时间分别为30m in、40m in和50m in,第4d起每天持续跑台60m in。结果:4周有氧训练后,A组和B组的血清指标IL-1Ra、IL-4、IFN-γ等均显著高于C组(P<0.01);4周跑台训练后B组血清指标IL-1Ra、IFN-γ等显著低于第1周(P<0.01),而血清指标IL-4无显著变化(P>0.05)。结论:4周有氧训练能够逆转Ⅱ型糖尿病大鼠血清指标IL-1Ra、IFN-γ的上调;IFN-γ/IL-4比值下降;但4周有氧训练后大鼠血清指标IL-4无显著变化。     

壳寡糖及其衍生物对实验性糖尿病大鼠调节血脂和抗氧化作用

研究了不同剂量的壳寡糖，N-乙酰氨基单糖对STZ诱导的糖尿病大鼠的调节血脂和抗氧化作用．按65mg／kg一次性腹腔内注射（ip）STZ制备糖尿病大鼠模型，随机分成糖尿病治疗组和糖尿病对照组．治疗组分剐用壳寡糖、N-乙酰氨基单糖水溶液按每日250mg／kg，500mg／kg，1500mg／kg灌胃，正常对照组，阴性对照组按体重灌胃等体积蒸馏水（10mL／kg），阳性对照组按每日200mg／kg灌胃二甲双胍水溶液，连续60d．对DM大鼠血清中谷胱甘肽过氧化物酶、超氧化物歧化酶、丙二醛浓度以及总抗氧化能力及甘油三酯、总胆固醇、载脂蛋白A1、载脂蛋白B、载脂A1/载脂B等指标进行测定．研究结果表明不同荆量的壳寡糖和N-乙酰氨基单糖均能不同程度地改善糖尿病大鼠的体重减轻、多饮、多食等症状．壳寡糖各剂量组对总抗氧化能力、SOD活力均有显著改善，MDA浓度与阴性对照组比较均有极其显著差异（P〈0．001），且剂量越高总抗氧化能力越强，MDA浓度越小，但SOD活力降低．壳寡糖组甘油三酯与正常组浓度无显著差异，胆固醇浓度轻度升高，载脂蛋白B质量浓度相对阴性对照组降低，中剂量组有显著差异（P〈0．050），各剂量组载脂A1／载脂B值与阴性对照组比较有显著差异，中剂量组效果最好；N-乙酰氨基单糖各剂量组对总抗氧化能力的改善效果与阴性对照组比较均无显著差异（P〉0．050），中、低剂量组SOD活力显著升高，MDA浓度与阴性对照组比较均有极其显著差异（P〈0．001），且剂量越低总抗氧化能力越强，MDA浓度越小，SOD活力增加．N-乙酰氨基单糖各剂量组甘油三酯，载脂蛋白B质量浓度相对阴性对照组较低，裁脂A1／载脂B值降低与阴性对照组比较均有极显著差异（P〈0．01），低剂量组效果最好．不同剂量的壳寡糖和N-乙酰氨基单糖均能不同程度地调节糖尿病大鼠血脂和提高其机体抗氧化能力，壳寡糖中、高剂量组与N-乙酰氨基单糖低剂量组效果较好．     

下尿路梗阻对大鼠逼尿肌肌条自发性收缩影响的实验研究

观察下尿路梗阻对大鼠逼尿肌肌条自发性收缩的影响。建立Wistar大鼠膀胱下尿路梗阻动物模型 ,6周后行充盈性膀胱测压 ,根据有否逼尿肌不稳定 (逼尿肌稳定 )将膀胱下尿路梗阻动物分为逼尿肌不稳定组和逼尿肌稳定组 ,用拉力传感器检测离体逼尿肌肌条的自发性收缩的频率及收缩幅度。分别进行统计和分析。比较逼尿肌肌条自发性收缩频率及收缩幅度 ,证实逼尿肌不稳定组较逼尿肌稳定组及正常对照组明显增强 (P <0 0 5 ) ;正常对照组与逼尿肌稳定组之间无显著差异 (P >0 .0 5 ) ;提示下尿路梗阻使逼尿肌自发性收缩的节律发生改变 ,是引起逼尿肌不稳定发生的一个重要因素。     

Spontaneous forward mutation versus reversion frequencies for maize Adh1 in pollen

Reliable quantitative data on spontaneous, specific gene mutation frequencies in higher plants and animals are few. Detergents include low natural frequencies and difficulty in obtaining in excess of 10(6) scorable organisms or gametophytes. The alcohol dehydrogenase-1 gene (Adh1 gene; ADH enzyme EC 1.1.1.1.), as expressed in pollen grains, is among the exceptionably suitable; much is known about the maize ADHs, Adh1 function is totally dispensible in an aerobic environment and maize pollen is a trinucleate gametophyte which expresses much of its haploid genome, including Adh1. In particular, there have been two recent methodological advances. First, I am able to cytochemically stain pollen, before or after in vitro germination, for the presence of above 5% normal ADH activity. And second, ADH1- pollen grains survive allyl alcohol (C=C-C-OH) vapour concentrations which kill ADH1+ grains; this selection scheme was developed for yeast by Megnet. My genetic resolution is approximately one mutant (Adh1+-->ADH-) per 10(7) chemically selected, viable gametophytes, and one (phenotypic) revertant (Adh1--->ADH+) per 10(8) unselected gatetophytes. In this note, I compare spontaneous forward mutant frequency with previously published revertant frequencies for one naturally occurring and six ethyl methanesulphonate-induced Adhl-deficient (Adh1-) alleles.     

沙雅隆起白垩系卡普沙良群层序地层与沉积模式

综合运用钻井、测井和地震资料,对塔里木盆地沙雅隆起白垩系卡普沙良群进行了层序地层及沉积相研究。沙雅隆起处于库车前陆盆地的前隆带和隆后坳陷,卡普沙良群对应于一幕逆冲构造活动,其内细分的3个层序（SQ1-SQ3）对应前陆盆地的不同演化阶段。SQ1处于逆冲构造活动的初始期,低位体系域占主导,前隆带中部剥蚀,其两侧斜坡发育来自该剥蚀区的扇三角洲、辫状河三角洲沉积,隆后坳陷则发育来自前隆带及盆地腹部的三角洲沉积;SQ2处于逆冲构造活动增强期,湖侵体系域相对发育,前隆带整体沉降至水下,以滨浅湖沉积为主,隆后坳陷则主要发育曲流河三角洲沉积;SQ3处于逆冲构造活动减弱期和停滞期,以高位体系域的相对发育为特征,前隆带和隆后坳陷成为一体,发育曲流河三角洲和辫状河三角洲沉积。