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INTESTINAL MUSCLE EFFECTS OF CLOSTRIDIUM DIFFICILE TOXIN

艰难梭菌毒素对肠肌肉的影响

基本信息

批准号：
3454523
负责人：
RICHARD J GILBERT
金额：
$ 11.17万
依托单位：
STEWARD ST. ELIZABETH'S MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
1989
资助国家：
美国
起止时间：
1989-07-01 至 1994-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/3454523
关键词：
Clostridium difficile bacterial toxins calcium flux clostridial infection colitis cyclic nucleoside monophosphate diarrhea electrophysiology gastrointestinal epithelium gastrointestinal motility /pressure intestines ion transport leukocytes membrane permeability smooth muscle

项目摘要

Toxins derived from the bacterium Clostridium difficile are the principal cause of antibiotic-associated diarrhea. Although it is known that many of the clinical manifestations of this and other infectious diarrheal states are due to involvement of intestinal muscle, the pathophysiological basis of muscle cell dysfunction is unknown. We propose that the effects of C. difficile on intestinal smooth muscle result from: 1) The direct effects of toxin B on smooth muscle membrane electrophysiology and intracellular calcium metabolism, 2) The indirect effect of toxin A via inflammatory mediators released by activated leukocytes, and 3) The modulation of enteric nerve activity resulting in changes of neurotransmitter or peptide release. The overall goal of this proposal is to determine the role of each of these phenomenon in the motility response of the intestine to C. difficile, and to ascertain their underlying cellular mechanisms. First, since our preliminary data suggests that toxin B causes inhibition of calcium conductance in intestinal smooth muscle, we will evaluate the membrane electrophysiological response to toxin by studies of excitation- contraction coupling in tissue strips and membrane electrophysiology in isolated cells. The degree to which the effects of toxin B are a function of changes of cystosolic calcium will be studied by correlating changes of cell size and free cytosolic calcium in enzyme-dispersed muscle cells, and measurement of calcium release in saponin-permeabilized cells. Second, the effects of toxins on enteric nerves will be directly studied by measurements of intracellular membrane electrophysiology, synaptic potentials in response to extracellular fiber stimulation, and response to exogenous agonists in myenteric and submucosal nerves in situ. Third, inasmuch as we have shown that toxin A in vivo results in the release of eicosanoids and that in vitro leukotriene results in muscle membrane depolarization, we will specifically study the role of leukotrienes C4 and D4 in mediating changes of membrane excitability in isolated smooth muscle cells and enteric nerves. These studies are expected to increase our understanding of the cellular basis of the motility response to C. difficile, and to enhance understanding of the general mechanisms by which infectious agents act on gastrointestinal muscle.

源自艰难梭菌的毒素是主要毒素抗生素相关性腹泻的原因。尽管众所周知，许多这种感染性腹泻状态和其他感染性腹泻状态的临床表现是由于肠肌受累所致，其病理生理基础肌细胞功能障碍的原因尚不清楚。我们建议C的影响。艰难梭菌对肠道平滑肌的直接作用是： 1) 毒素 B 对平滑肌膜电生理和细胞内的影响钙代谢，2) 毒素 A 通过炎症的间接作用激活的白细胞释放的介质，以及 3) 的调节肠神经活动导致神经递质或肽的变化发布。该提案的总体目标是确定肠道对 C 的运动反应中的每一种现象。艰难梭菌，并确定其潜在的细胞机制。首先，由于我们的初步数据表明毒素 B 会引起抑制肠平滑肌钙电导的影响，我们将评估通过兴奋研究膜对毒素的电生理反应组织条中的收缩耦合和膜电生理学分离的细胞。毒素 B 的作用发挥作用的程度将通过关联变化来研究囊溶钙的变化酶分散的肌肉细胞中的细胞大小和游离胞质钙，以及皂苷渗透细胞中钙释放的测量。其次，将直接研究毒素对肠神经的影响细胞内膜电生理学、突触测量响应细胞外纤维刺激的电位，以及响应肌间神经和粘膜下神经原位的外源性激动剂。第三，因为我们已经证明毒素 A 在体内会导致释放类二十烷酸和体外白三烯导致肌肉膜去极化，我们将专门研究白三烯C4和 D4 介导离体平滑肌膜兴奋性变化细胞和肠神经。这些研究有望增加我们对细胞的了解对艰难梭菌的运动反应的基础，并增强了解感染因子作用的一般机制胃肠肌肉。