Oxygen-derived free radicals and postischemic myocardial reperfusion: therapeutic implications

Oxygen-derived free radicals have been implicated in the pathogenesis of various disease states, including myocardial ischemia and reperfusion. In this article, we review 1) the evidence linking free radical production and myocardial injury during myocardial ischemia and reperfusion and 2) results of studies of the effects of the pharmacological therapies available potentially to prevent free radical-mediated injury. Free radicals can be produced during ischemia and reperfusion by several different biochemical pathways. Of these, the xanthine oxidase reaction and the output of free radicals by neutrophils that have accumulated in damaged tissue have been studied extensively. When produced, free radicals can potentially damage myocytes or endothelial cells through peroxidation of membrane lipids or damage to proteins or nucleic acids. Using electron spin resonance spectroscopy, several studies have shown a 'burst' of oxygen free radicals immediately after reperfusion. Moreover, exogenous generation of intravascular free radicals has been shown to produce marked vascular and myocyte damage, as well as contractile dysfunction. 'Anti-free radical' interventions, such as xanthine oxidase inhibitors and free radical scavengers have been reported to prevent contractile dysfunction and reperfusion-induced arrhythmias after an episode of reversible ischemic injury. However, after more severe episodes of ischemia, such interventions have had conflicting effects on myocardial infarct size. 'Anti-free radical' interventions could be of potential use in situations where reversible ischemic injury occurs. In situations where reperfusion is achieved after irreversible ischemic injury has occurred, the potential beneficial effect of these treatments on infarct size is more doubtful.     

Intravascular signal in MR imaging: use of phase display for differentiation of blood-flow signal from intraluminal disease

Intravascular signal from flowing blood is frequently observed on magnetic resonance (MR) images and may be indistinguishable from partial or complete vascular occlusion caused by thrombus or tumor. With a phase-display reconstruction method, qualitative assessment of large-vessel patency within the abdomen was undertaken in 15 healthy subjects and 12 patients with angiographically or surgically documented intravascular thrombus or tumor. Computed tomographic (CT) scans were available in all patients for correlation. MR studies were performed with a multisection spin-echo pulse sequence and two-dimensional Fourier transform spatial encoding. Data acquired from a single sequence was reconstituted in two ways to provide both routine anatomic images and a pictorial representation of large-vessel flow on a phase-sensitive image. With this method, reliable and easy differentiation of intraluminal thrombus and tumor from blood flow signal within large vessels was achieved. Information from these phase-display images compared favorably with findings from angiography and contrast-enhanced CT in the determination of luminal patency and obstruction.     

Epipolis laser in-situ keratomileusis: an evolving surface ablation procedure for refractive corrections

PURPOSE OF REVIEW: The aim of this article is to provide an update on epipolis laser in-situ keratomileusis--an alternative surface photorefractive surgical technique for the correction of myopia. RECENT FINDINGS: In-vivo studies on animal models provide evidence that the replacement of the epithelial sheet on an ablated cornea can control corneal wound healing. Preliminary clinical data confirm that epipolis laser in-situ keratomileusis can provide excellent long-term visual and refractive results. The problems of late visual rehabilitation and postoperative pain, however, have not yet been fully addressed. SUMMARY: Being a recently introduced surgical photorefractive technique for ametropias correction, epipolis laser in-situ keratomileusis is a fast evolving area of interest for refractive surgeons.     

模拟教学在继续医学教育中的应用探讨

目前,模拟技术在院校医学教育和毕业后医学教育以及其他医疗卫生专业人员的个人训练和评估中有广泛的应用,模拟技术能给各种技术水平的医疗卫生专业人员提供安全、有效的实践机会,帮助他们学会治疗患者所需的临床技能.有越来越多的研究证实了模拟技术对于医疗卫生专业人员的培训效果.然而,在继续医学教育领域,模拟技术还未得到广泛的应用.     

Capsule endoscopic features of Crohn's disease

Background: Crohn's disease (CD) is becoming increasingly recognized in Indian patients. As this disease often affects the small bowel, capsule endoscopy can help diagnose this disease and add valuable information regarding the extent of the disease. Our aim is to report our experience with the wireless capsule endoscope in patients with either known or suspected CD. Methods: Patients referred for capsule endoscopy with known or suspected CD were studied. All patients underwent precapsule endoscopy colonoscopy and small bowel series examination. After an overnight fast and bowel preparation, the capsule was ingested and the data were recorded for 8 h on the external recording device. A gastroenterologist experienced in reading capsule endoscopy interpreted images. Results: Eleven patients (mean age 42 years [range 14–70], 7 males) underwent capsule examination. Seven patients had symptoms suggestive of CD with no precapsule evidence of the disease, one had suspected small bowel pseudo‐obstruction and three had known CD. All patients had lesions in the small intestine consistent with CD. Two patients had strictures that led to a retained capsule, despite precapsule small bowel series. Conclusions: Capsule endoscopy is emerging as a small bowel imaging modality that can greatly assist in making the diagnosis of CD. Small bowel radiology is unreliable in excluding strictures that may cause capsule retention.     

等离子低温扁桃体消融术治疗阻塞性睡眠呼吸暂停综合征

目的：探讨等离子低温射频扁桃体消融术治疗阻塞性睡眠呼吸暂停低通气综合征的效果。方法：用等离子低温扁桃体消融术治疗阻塞性睡眠呼吸暂停低通气综合征(OSAHS)45例，于术前及术后12周行多导睡眠仪监测和Epworth嗜睡程度评分以确定治疗效果。结果：术后随访3-6个月，患者均取得了满意的疗效。与治疗前比较，最低血氧饱和度(LSPO2)显著提高(P＜0．05)；呼吸暂停低通气指数减低，差异有高度显著性(P＜0．01)。扁桃体缩小及鼾声评级降低程度与治疗前差异有高度显著性(P＜0．01)，Epworth嗜睡程度评分亦明显降低(P＜0．01)。结论：等离子低温扁桃体射频消融术具有较好的临床疗效，且方便、安全、微创，无不良反应，有较好的应用前景。