The Catalytic Mechanism of Angiotensin Converting Enzyme

A detailed investigation of the catalytic mechanism of angiotensin converting enzyme was undertaken in order to establish a molecular basis for its mode of action. These studies include the characterization of the kinetic properties of the enzyme. In particular, a mechanism for the anion activation, a characteristic feature of angiotensin converting enzyme, has been established. The active site of the enzyme contains a catalytically essential zinc atom which appears to be directly involved in the hydrolytic step of catalysis. Further components of the active site are the carboxyl group of an aspartyl or glutamyl residue, tyrosyl, arginyl and lysyl residues. The latter one is involved in mediating the anion activation. These results have enabled us to compare the active site of angiotensin converting enzyme with those of two other zinc peptidases and, thereby, deduce a mechanism for its mode of action. These investigations have confirmed a hypothetical model of the active site of angiotensin converting enzyme which has served to construct potent inhibitors of the enzyme now being used as anti-hypertensive agents.     

Measurement of brain natriuretic peptide in plasma samples and cardiac tissue extracts by means of an immunoradiometric assay method

Background: The mechanisms of oxygen‐induced effects on blood vessels (vasoconstriction in hyperoxaemia and vasodilatation during hypoxaemia) are uncertain. Many investigators have suggested that the vasoconstriction seen during hyperoxia/hyperoxaemia is mediated through the endothelium as a result of either increased release or activity of vasoconstrictors (oxygen radicals, endothelin, norepinephrine, angiotensin II, or serotonin (5‐HT)), or reduced activity of vasodilators (prostaglandin E₂ and nitric oxide). Serotonin has been assumed to have a central role. Methods: Eight healthy volunteers were exposed to F_iO₂ of 1.0 for 20?min and serum concentrations of serotonin and activated platelets were measured (indicated by concentrations of β‐thromboglobulin (β‐TG)). Results. During hyperoxaemia in humans, serum concentrations of serotonin and β‐TG remained unchanged. Conclusion: If serotonin is involved in oxygen‐induced vasoconstriction, the mechanism is more likely to be either a potentiating effect of serotonin on other vasoconstrictors or increased activity of serotonin on its receptor.     

Angiotensin receptor antagonists in patients with nephropathy due to type 2 diabetes

In the past few years diabetes has become the leading cause of end-stage renal disease in all Western countries. A correlation between blood pressure and rate of progression in diabetic nephropathy was noted very early, and increased local activity of the renin angiotensin system was identified as a major pathophysiological mechanism for proteinuria and nephrosclerosis in diabetic patients. Angiotensin converting enzyme (ACE) inhibitors have been shown to slow progression of nephropathy in type 1 diabetic patients. The majority of diabetic patients with nephropathy, however, are suffering from type 2 diabetes and until last year there was no convincing evidence of ACE inhibitors being able to slow progression in type 2 diabetic patients with nephropathy. Three new studies now fill this gap, showing that angiotensin receptor blockers (ARB) are nephroprotective in patients with type 2 diabetes, independently of blood pressure. This review provides an in-depth discussion of the results of these studies and provides recommendations for patient management.     

香青兰总黄酮对血管紧张素Ⅱ诱导血管平滑肌细胞黏附分子及基质金属蛋白酶表达的影响

目的：研究香青兰总黄酮对血管紧张素Ⅱ（AngⅡ）诱导的大鼠主动脉血管平滑肌细胞（VSMC）黏附分子及基质金属蛋白酶（MMPs）表达的影响。方法：采用贴壁法培养大鼠胸主动脉平滑肌细胞,以AngⅡ为诱导剂,建立VSMC细胞增殖的模型,分别应用10^-7 mol·L^-1AngⅡ以及AngⅡ+不同浓度香青兰总黄酮组（25,50,100 μg·mL^-1）作用24 h,并设空白对照组进行比较。采用免疫组化法检测细胞中细胞间黏附分子（ICAM-1）、血管间黏附分子（VCAM-1）的表达水平。RT-PCR方法检测细胞MMP-2、MMP-9的mRNA表达水平。结果：与对照组比较,AngⅡ组能显著刺激大鼠VSMC细胞内ICAM-1、VCAM-1、MMP-2、MMP-9的表达,香青兰总黄酮不同剂量组联合AngⅡ可在一定程度上抑制AngⅡ诱导的VSMC细胞内ICAM-1、VCAM-1、MMP-2、MMP-9的表达,且呈现一定的剂量依赖关系趋势。结论：香青兰总黄酮具有抑制AngⅡ诱导VSMC黏附分子及基质金属蛋白酶表达的作用。     

牛磺酸对高血压和血管活性物质的影响

在原发性高血压(EH)患者、大鼠腹主动脉狭窄和高盐摄入引起高血压模型上,观察到口服牛磺酸治疗4周后均明显降低平均动脉压和收缩压,42.2%的患者血压恢复正常,并能抑制EH患者和高血压大鼠血浆内皮素(ET)、血管紧张素II(AII)水平的升高,增加高血压大鼠血浆降钙素基因相关肽(CGRP)和主动脉组织中的牛磺酸含量.以上结果表明,牛磺酸在降压作用同时伴有缩血管物质的降低和舒血管物质的增加,为以牛磺酸作为降血压辅助药物提供了依据.     

Angiotensin converting enzyme inhibitor-induced angioedema: a report of two cases

Angioedema is a rare but potentially fatal side effect of angiotensin converting enzyme (ACE) inhibitors. We report for the first time, two children with systemic lupus erythematosus who developed acute angioedema after the long-term use of enalapril. Prompt recognition and appropriate management of ACE-induced angioedema prevented life-threatening complications. This report highlights the potential risks of angioedema associated with the use of ACE inhibitors in children. Patients should be advised to seek medical treatment immediately if they experience swelling of the face, neck, or tongue, and especially if they have trouble breathing, speaking, or swallowing. Received: 12 March 1999 / Revised: 8 June 1999 / Accepted: 8 June 1999     

SH-SY5Y神经细胞中α7神经型尼古丁受体基因沉默对CaM、CaMKⅡ蛋白水平的影响

目的构建稳定的α7 n AChR沉默的神经母细胞瘤细胞(SH-SY5Y)细胞,研究α7神经型尼古丁受体(n AChR)基因沉默对钙调蛋白(Ca M)、钙调素依赖性蛋白激酶Ⅱ(Ca MKⅡ)水平的影响,了解α7 n AChR神经保护作用及其与阿尔茨海默病(AD)发病机制的关系。方法将α7 n AChR shRNA重组质转染到SH-SY5Y,用含嘌呤霉素的培养液筛选,挑选阳性克隆后采用实时荧光定量PCR和蛋白质印迹方法(Western-blot)检测细胞中α7n AChR mRNA及蛋白表达水平的变化;Western-blot方法测定Ca M、Ca MKⅡ蛋白表达水平。结果获得稳定转染α7 n AChR shRNA重组质粒的细胞克隆株,与对照组相比,α7 n AChR mRNA及蛋白表达量分别减少了95%和80%。Ca M、Ca MKⅡ蛋白表达量分别减少了48.5%和35%。结论成功构建了α7 n AChR mRNA沉默的SH-SY5Y细胞细胞株,α7 n AChR沉默降低了Ca M、Ca MKⅡ的蛋白水平,可能影响信号通路转导,这可能与阿尔茨海默病(AD)的发病有一定的关系。     

SH-SY5Y神经细胞中α7神经型尼古丁受体基因过表达对CaMK Ⅱ和CREB的影响

目的研究SH-SY5Y神经细胞中α7 nAChR基因过表达对CaMKⅡ和CREB的影响。方法复苏稳定转染α7 nAChR-pc DNA3.1质粒及空载质粒的SH-SY5Y神经细胞后,用含G418的培养液进行筛选培养;应用实时荧光定量PCR法和蛋白印迹法(Western blot)检测α7 nAChR基因过表达组、空载质粒组和正常对照组细胞中CaMKⅡ、CREB mRNA及蛋白表达水平的变化。结果与对照组相比,α7 nAChR基因过表达细胞组的CaMKⅡ、CREB mRNA表达水平分别增加了116.8%和114.7%(P0.01);及CaMKⅡ、CREB蛋白表达水平分别增加了8.7%(P0.05)和41.4%(P0.05)。结论α7 nAChR的神经保护作用可能与上调细胞CaMKⅡ、CREB水平有关。     

肺癌组织分型与转化生长因子-βⅡ型受体和肿瘤相关性巨噬细胞计数的关系

目的 检测肺腺癌和肺鳞状细胞癌中转化生长因子-βⅡ型受体(TGF-βRⅡ)和肿瘤相关性巨噬细胞(TAMs)计数,探讨两者与肺腺癌和肺鳞状细胞癌的关系.方法 应用免疫组织化学法检测TGF-βRⅡ蛋白和TAMs在肺腺癌和肺鳞状细胞癌组织中的表达,并与癌旁正常肺组织中的表达进行比较.结果 (1)TGF-βRⅡ蛋白的表达在肿瘤组织中明显降低(P＜0.01),其表达下调与肺癌的组织学类型、淋巴结转移、临床分期相关(P＜0.05).(2)TAMs在肿瘤间质内浸润数量明显增多(P＜0.01),并与肺癌的组织学类型、肿瘤大小、淋巴结转移、临床分期密切相关(P＜0.05).结论 TGF-βRⅡ蛋白表达水平降低可促进肺癌的发生、浸润和转移,对肺腺癌发生或进展影响很大,并可能通过下调TGF-βRⅡ的表达、诱导TAMs至肿瘤间质,从而促进肿瘤的发生、发展,且这种作用在非小细胞肺癌中具有较普遍的意义.     

丹参酮ⅡA诱导瘢痕疙瘩成纤维细胞凋亡及细胞周期阻滞的实验研究

目的观察丹参酮ⅡA对人瘢痕疙瘩成纤维细胞增殖、凋亡及细胞周期的影响。方法体外培养人瘢痕疙瘩成纤维细胞,予含有不同浓度丹参酮ⅡA的培养液(分别为0μg/mL、50μg/mL、100μg/mL和200μg/mL)进行干预。不同时间点以CCK-8检测细胞增殖活力,流式细胞仪检测细胞凋亡、细胞周期的变化。结果不同浓度丹参酮ⅡA干预和不同时间干预,对瘢痕疙瘩成纤维细胞的增殖活性、早期凋亡率、细胞周期G0/G1期比例的影响,均具有统计学意义(P<0.001),其中200μg/mL组干预效果最明显。结论丹参酮ⅡA具有抑制瘢痕疙瘩成纤维细胞增殖,诱导凋亡并阻滞细胞周期的作用,且干预效果存在浓度依耐性及时间依耐性。