Structural and metabolic changes in cardiac conducting system during massive pulmonary embolism

We studied structural and metabolic changes in ventricular conducting cardiomyocytes during the acute phase of massive pulmonary embolism complicated or uncomplicated by cardiac insufficiency. During massive pulmonary embolism without cardiac insufficiency, glycolysis in conducting cardiomyocytes of both ventricles was activated, and its contribution to energy formation increased. Massive pulmonary embolism complicated by cardiac insufficiency was accompanied by inhibition of glycolytic enzymes and damages to conducting cardiomyocytes of the left and right ventricles. Our findings indicate that the development of cardiac insufficiency during the acute phase of massive pulmonary embolism provides structural and morphological basis for impairment of electrophysiological properties of the myocardium. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 10, pp. 382–387, October, 2000     

Arylamine N-acetyltransferase activity in bronchial epithelial cells and its inhibition by cellular oxidants

Bronchial epithelial cells express xenobiotic-metabolizing enzymes (XMEs) that are involved in the biotransformation of inhaled toxic compounds. The activities of these XMEs in the lung may modulate respiratory toxicity and have been linked to several diseases of the airways. Arylamine N-acetyltransferases (NAT) are conjugating XMEs that play a key role in the biotransformation of aromatic amine pollutants such as the tobacco-smoke carcinogens 4-aminobiphenyl (4-ABP) and β-naphthylamine (β-NA). We show here that functional human NAT1 or its murine counterpart Nat2 are present in different lung epithelial cells i.e. Clara cells, type II alveolar cells and bronchial epithelial cells, thus indicating that inhaled aromatic amines may undergo NAT-dependent biotransformation in lung epithelium. Exposure of these cells to pathophysiologically relevant amounts of oxidants known to contribute to lung dysfunction, such as H₂O₂ or peroxynitrite, was found to impair the NAT1/Nat2-dependent cellular biotransformation of aromatic amines. Genetic and non genetic impairment of intracellular NAT enzyme activities has been suggested to compromise the important detoxification pathway of aromatic amine N-acetylation and subsequently to contribute to an exacerbation of untoward effects of these pollutants on health. Our study suggests that oxidative/nitroxidative stress in lung epithelial cells, due to air pollution and/or inflammation, could contribute to local and/or systemic dysfunctions through the alteration of the functions of pulmonary NAT enzymes.     

A high-throughput screen for quorum-sensing inhibitors that target acyl-homoserine lactone synthases

Many Proteobacteria use N-acyl-homoserine lactone (acyl-HSL) quorum sensing to control specific genes. Acyl-HSL synthesis requires unique enzymes that use S-adenosyl methionine as an acyl acceptor and amino acid donor. We developed and executed an enzyme-coupled high-throughput cell-free screen to discover acyl-HSL synthase inhibitors. The three strongest inhibitors were equally active against two different acyl-HSL synthases: Burkholderia mallei BmaI1 and Yersinia pestis YspI. Two of these inhibitors showed activity in whole cells. The most potent compound behaves as a noncompetitive inhibitor with a K_i of 0.7 µM and showed activity in a cell-based assay. Quorum-sensing signal synthesis inhibitors will be useful in attempts to understand acyl-HSL synthase catalysis and as a tool in studies of quorum-sensing control of gene expression. Because acyl-HSL quorum-sensing controls virulence of some bacterial pathogens, anti–quorum-sensing chemicals have been sought as potential therapeutic agents. Our screen and identification of acyl-HSL synthase inhibitors serve as a basis for efforts to target quorum-sensing signal synthesis as an antivirulence approach.     

Measurement of multiple drugs in urine,water, and on surfaces using fluorescence covalent microbead immunosorbent assay

There are a range of applications that require the measurement of multiple drugs such as urine analysis, drug determination in water, and screening for drug contamination on surfaces. Some of the procedures used such as enzyme-linked immunosorbent assay (ELISA) are simple but can only determine one drug at a time, and others such as GC-MS or LC-MS are complex, time-consuming, and expensive. In this study, fluorescence covalent microbead immunosorbent assay (FCMIA) was investigated as a simple method for the measurement of multiple drugs simultaneously in three matrices: diluted urine, water, and on surfaces. Five different drugs of abuse or their metabolites (methamphetamine, caffeine, benzoylecgonine (a metabolite of cocaine), tetrahydrocannabinol (THC), the active ingredient in marijuana, and oxycodone) were studied over the range 0–15?ng/ml. There was no measureable cross-reactivity among the drugs at the concentrations studied. Urine dilutions from 1/50 to 1/2.5 were studied and dilutions less than 1/20 had a significant effect on the methamphetamine assay but limited effects on the benzoylecgonine and oxycodone assays and almost no effect on the THC assay. For assays performed in 1/20 urine dilution, water, and diluted surface sampling buffer, least detectable doses (LDD) were 1?ng/ml or less for the drugs. Surfaces spiked with drugs were sampled with swabs wetted with surface sampling buffer and recoveries were linear over the range 0–100?ng/100?cm² surface loading for all drugs. FCMIA has potential to be used for the measurement of multiple drugs in the matrices studied.     

Effects of serum from trypsin inhibitor fed rats on enzyme secretion and protein synthesis by exocrine pancreatic cells

Oral feeding of trypsin inhibitor is known to stimulate rat pancreatic enzyme secretion and cause hypertrophy of the pancreas. In an attempt to detect a possible serum factor(s) responsible, the effects of serum from trypsin inhibitor fed rats on enzyme secretion and protein synthesis by isolated exocrine rat pancreatic cells in suspension were studied.

Serum from trypsin inhibitor fed rats stimulated the secretion of pancreatic enzymes significantly more than serum from control rats. The data suggest that a humoral factor or factors may be involved in the stimulation of pancreatic enzyme secretion by oral trypsin inhibitor.

Serum from trypsin inhibitor fed rats as well as serum from control rats stimulated the ³H-leucine incorporation into protein (protein synthesis) to a significant extent. There was, however, no difference in the effects of the two types of sera in this respect.     

A Simple Amidolytic Method for the Determination of Functionally Active Antithrombin III

A simple amidolytic method for the determination of the concentration of functionally active antithrombin III is described. Plasma is diluted with buffer containing EDTA and Polybrene®. In stage I, diluted plasma is incubated with thrombin. EDTA retards fibrin polymerization, and plasma fibrinogen does not influence the assay. Polybrene makes the assay result independent of heparin. In stage II, remaining thrombin is determined with the chromogenic substrate benzoyl-Phe-Arg-p-NA. The method is simpler and has a higher accuracy than clotting methods. There is a close correlation between the results obtained with this assay and with immunoassay of antithrombin III.     

肺部疾病患者血清血管紧张素转换酶活性的变化

目的：探讨血清血管紧张素转换酶（ａｎｇｉｏｔｅｎｓｉｎｃｏｎｖｅｒｔｉｎｇ ｅｎｚｙｍｅ ， Ａ Ｃ Ｅ） 活性变化对肺部疾病诊断的价值。方法：采用紫外比色法检测血清 Ａ Ｃ Ｅ 活性。结果：肺炎及肺结核患者血清 Ａ Ｃ Ｅ 活性分别为（３５１ ±９３） Ｕ／ Ｌ 和（３９６ ±１０２） Ｕ／ Ｌ，与对照组（３７４ ±９４） Ｕ／ Ｌ 相比均无显著性差异（ Ｐ＞ ００５） ，３６例肺癌患者血清 Ａ Ｃ Ｅ 活性（２９２ ±９６） Ｕ／ Ｌ，明显低于肺炎、肺结核患者及对照组；６７ 例肺结节病患者血清 Ａ Ｃ Ｅ 活性（６５８ ±１３６） Ｕ／ Ｌ，明显高于对照组、肺癌、肺炎及肺结核组（ Ｐ＜ ０００１） 。结论：血清 Ａ Ｃ Ｅ 活性测定可作为诊断肺癌或肺结节病的重要指标，有助于肺癌、肺结节病和肺结核、肺炎的鉴别诊断。     

合肥地区献血员庚型肝炎病毒的分子生物学研究

目的了解台肥地区献血员的庚型肝炎病毒(GBV—C／HGV)感染情况。方法应用酶免疫测定法(EIA)和逆转录一套式多聚酶链反应法(RT—PCR)分别检测献血员中的抗-GBV-C/HGV和GBV-C/HGV RNA。结果 献血员中抗-GBV—C/HGV检出率为1．7％(18／1 050)．抗-GBV—C／HGV阳性血清中GBV／HGV RNA占66.7％(12/18)；男性和低年龄组献血员抗-GBV—C／HGV阳性率分别低于女性和高年龄组．两差异有显性(P<0.05)；抗-GBV—C／HGV阴性的献血员有6名转为阳性，2名抗-GBV-C/HGV和GBV-C／HGV RNA阳性的献血员有1名转为阴性。结论GBV—C／HGV在合肥地区献血员中有较高的感染率；献血员中存在着GBV-C／HGV阳性但ALT正常的献血员，应尽快对献血员进行GBV-C／HGV感染指标的检测。     

Recent advances in pharmacotherapy of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia associated with increased morbidity and mortality. Efficacy and safety of currently employed antiarrhythmic drugs (AADs) continue to be less optimal in AF. Development of newer AADs has recently been made possible through a greater understanding of electro-pathophysiology of AF. Highly specific drugs acting on atria are currently being explored, although there is little data available on effectiveness of atrial specific agents in maintaining sinus rhythm. Combining AADs and non-AADs such as angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) may increase effectiveness of AADs in patients with AF. Controlled clinical trials are required to precisely define the efficacy of single agents versus various combinations in maintaining sinus rhythm in patients with AF. This review describes some of the most promising therapeutic approaches that may overcome some of the limitations of drugs used at present for the management of AF.     

AT1受体拮抗剂和ACEI对MI后心室重构作用的比较

心肌梗死 ( myocardial infarction,MI)后心室重构对 MI患者的预后具有深远的影响。 MI后循环和心脏局部组织中的肾素 -血管紧张素系统 ( renin-angiotensin system ,RAS)被激活 ,在刺激全身和心脏局部产生代偿反应的同时 ,也带来危害——心肌肥厚和间质纤维化。应用血管紧张素转换酶抑制剂 ( angiotensin converting enzyme inhibitor,ACEI)阻断这一系统 ,已显示出具有防止心脏重构、延长患者生存时间的作用。其作用主要归因于抑制循环及局部血管紧张素 ( angiotensin ,Ang )的生成 ,以及减少缓激肽 ( bradykinin,BK)的降解。与 ACEI相比 ,选择性 1型血管紧张素 受体 (简称 AT1受体 )拮抗剂在理论上能够更加长期、有效地阻断血管紧张素 通过其 1型受体发挥的作用 ,且其作用并不仅限于此。