Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO2). The patterns of ischemia without congestion (IHB, ISO2) during superior mesenteric artery occlusion, and ischemia with congestion (IHB, ISO2) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO2, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.Supported by the American Society for Gastrointestinal Endoscopy Career Development Award (H850208, H870212), Veterans Administration Medical Research Funds; and in part by research grants (0162-01, 0162-02; 0291-01) from the Smokeless Tobacco Research Council, Inc.; and by funds provided by the Cigarette and Tobacco Surtax Fund of the State of California through the Tobacco Related Disease Research Program of the University of California. 相似文献
Cytogenetic analysis of short-term cultures from a case of monostotic fibrous dysplasia in a 14-year-old girl revealed multiple clonal structural rearrangements with evidence of clonal evolution. The karyotype was 46,XX,del(3)(q27),add(10)(q22), add(12)(p13)/46,idem,t(3;8)(p21;q13),add(10)(q26),der(15)del(15)(q15q22)ins(15;?)(q15;?)/46,idem,-X, + 2,t(3;8),add(10),der(15). The finding of clonal structural aberrations suggests that fibrous dysplasia is a neoplastic lesion which develops as the result of somatic mutations. 相似文献
We report the finding of clonal structural chromosome abnormalities in short-term cultures from 15 squamous cell carcinomas of the head and neck region. When the distribution of chromosomal breakpoints in these 15 tumors and in the 16 head and neck carcinomas previously described are assessed, a marked clustering is seen at bands 1p22 and 11q13, which are rearranged in eight and nine tumors, respectively. No other band was involved in aberrations in more than five tumors. Cytogenetic evidence of gene amplification was seen in four tumors, three times in the form of homogeneously staining regions (twice located in 11q13), and in one tumor as double minutes. Among the candidate genes for such amplification are BCLI, INT2, and HSTI, all of which map to 11q13, and NRAS, which maps to 1p22. All these oncogenes have previously been shown to be amplified in subsets of head and neck carcinomas. We conclude that bands 1p22 and 11q13 are nonrandomly involved in chromosomal rearrangements in head and neck carcinomas and suggest that activation of oncogenes located in these bands may proceed via cytogenetic mechanisms. 相似文献
International reports recommend the improvement in the amount and quality of training for mental health workers in low and
middle income countries. The Scotland-Malawi Mental Health Education Project (SMMHEP) has been established to support the
teaching of psychiatry to medical students in the University of Malawi. While anecdotally supportive medical educational initiatives
appear of value, little quantitative evidence exists to demonstrate whether such initiatives can deliver comparable educational
standards. This study aimed to assess the effectiveness of an undergraduate psychiatry course given by UK psychiatrists in
Malawi by studying University of Malawi and Edinburgh University medical students' performance on an MCQ examination paper. 相似文献
There is considerable evidence that congestive heart failure (CHF) is paralleled by a decrease in the number of sarcolemmal β-receptors due to excessive levels of circulating endogenous catecholamines [1, 2]. In contrast, the myocardial H2-receptor system is not affected. The first clinically available specific H2-receptor agonist impromidine proved to be a potent inotrope in patients with CHF which were insensitive to catecholamine stimulation [3, 4]. Though the overall results of these initial studies were beneficial, the narrow therapeutic range, high costs of synthesis and the arrhythmogenic potential of impromidine limited its broad clinical application in large scale clinical trials. Recently developed phenylpyridylalkylguanidines [5] were investigated underin vitro andin vivo conditions in the guinea pig under physiologic and pathophysiologic conditions using impromidine as reference. Compounds tested were arpromidine and the difluorinated analogues BU-E-75 and BU-E-76, all guanidine-type H2-agonists with additional H1-antagonistic properties due to a pheniramine like moiety. In the isolated perfused heart, all three new compounds were more potent in increasing cardiac contractile force and coronary flow but less effective on heart rate and less arrhythmogenic. The same could be established underin vivo conditions where BU-E-76 was more potent than BU-E-75, arpromidine and impromidine, respectively, in augmenting LV dp/dt, LVP, cardiac output and systemic blood pressure, but all compounds were revealed to have less chronotropic and arrhythmogenic potential. In the vasopressin-induced acute heart failure model, BU-E-76 and BU-E-75 normalized within minutes all contractile parameters in contrast to arpromidine and impromidine. It is thus concluded that these new H2-receptor agonists may represent a promising therapeutic improvement for treatments of CHF patients, with a cardiovascular profile superior to impromidine and conventional catecholamines.