Medical hypotheses
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The incidence of sensorineural hearing loss often caused by direct damage to the cochlear hair cells is by far more frequent and more serious than disorders affecting the external ear or the middle ear. Mechanisms that are discussed to be relevant for the genesis of tinnitus and acquired hearing impairment are hair cell loss, signal transduction disturbances in the region of the outer and inner hair cells and the spiral ganglion, impairment of cochlear blood flow, mechanical disturbance, and hypoxia and ischemia. The present model surveys the possible cellular and molecular biological causes of peripherally developing hearing loss and tinnitus. ⋯ Moreover, the hypoxia inducible factor-1 may have an important role to play as a key transcription factor in the cells' adaptation to hypoxia and ischemia. An impairment of the cochlear blood flow may be induced by the expression of target genes like nitrogen monoxide synthase and endothelin-1 resulting in tinnitus. The paper discusses consequences resulting from the present model for the medical treatment of peripherally developing tinnitus and hearing loss.
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The likelihood of successful defibrillation in patients with sustained ventricular fibrillation (VF) is increased after administering thrombolytics during cardiopulmonary resuscitation (CPR). While dissolution of coronary artery thrombosis resolves the underlying cause of myocardial infarction in the majority of patients, improved microcirculatory reperfusion and alteration of the electrical activity of the fibrillation process may increase the likelihood of restoring spontaneous circulation in cardiac arrest patients. Electrocardiography is a sensitive means of displaying current myocardial perfusion in VF using changes in the frequency and amplitude of fibrillation. Our hypothesis postulates that thrombolytic therapy during CPR increases fibrillation frequency, fibrillation amplitude and amplitude spectrum area, thus improving ventricular fibrillation status and the chance of successful defibrillation.
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B-type natriuretic peptide (BNP) is released from cardiac ventricles in response to increased wall tension in patients with heart failure. It has been used as a biochemical marker for the diagnosis of congestive heart failure. BNP is also increased in patients with acute myocardial infarction, and is associated with an increased risk of cardiovascular mortality in those with impaired left ventricular function after myocardial infarction. We hypothesized that an increase in BNP soon after acute myocardial infarction is an independent predictor for long-term prognosis in patients with no clinical signs of left ventricular function.
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Diabetic retinopathy is a common and potentially devastating microvascular complication in diabetes and is a leading cause of acquired blindness among the people of occupational age. However, therapeutic options for the treatment of proliferative diabetic retinopathy, photocoagulation and vitrectomy, are limited by considerable side effects. Therefore, to develop novel therapeutic strategies that specifically target diabetic retinopathy is desired for patients with diabetes. ⋯ By blocking the protein prenylation, cerivastatin completely prevented the AGE-RAGE-elicited angiogenesis via suppression of vascular endothelial growth factor (VEGF). These observations let us to speculate that statins might be a promising remedy for treating patients with diabetic retinopathy by acting as a potential inhibitor of the AGE-RAGE signaling pathway in microvascular endothelial cells. In this paper, we would like to propose the possible ways of testing our hypotheses. (1) Does treatment with statins decrease the risk for the development and progression of diabetic retinopathy in patients with normocholesterolemia? (2) If the answer is yes, is this beneficial effect of statins superior to that of other cholesterol-lowering agents with equihypolipidemic properties? (3) Does statin treatment suppress retinal VEGF expression in diabetic patients? (4) Does treatment with pyridoxamine, a post-Amadori inhibitor of AGE formation, attenuate the beneficial effects of statins on diabetic retinopathy? These clinical studies could clarify whether the use of statins is of benefit in patients with AGE-RAGE-related disorders such as diabetic retinopathy, even in the absence of hypercholesterolemia.