Hypercholesterolemia-induced oxidative stress in heart and its prevention by vitamin E

Oxygen-free radicals have been implicated in hypercholesteolemic atherosclerosis. It is possible that hypercholesterolemia produces oxidative stress in myocardium. We therefore investigated the effects of a high cholesterol diet in the absence or presence of vitamin E on serum cholesterol and lipid peroxidation product malondialdehyde (MDA), chemiluminescence (M-CL), a measure of antioxidant reserve, and activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-P_x)] in cardiac muscles of rabbits. Rabbits were divided into four groups: Group I, regular rabbit chow diet; Group II, same as Group I + vitamin E; Group III, high cholesterol diet; Group IV, high cholesterol + vitamin E. The heart was removed under anesthesia at the end of 4 months on their respective diets for various biochemical measurements. Serum cholesterol in Groups III and IV increased to a similar extent. There was an increase in the levels of MDA, M-CL, GSH-P_x activity and a decrease in SOD activity in hypercholesterolemic rabbits in the absence of vitamin E. Vitamin E prevented the hypercholesterolemia-induced changes in cardiac MDA, M-CL, and GSH-P_x. These results suggest that hypercholesterolemia produces oxidative stress in the myocardium which may be due to a decrease in the antioxidant reserve, and that vitamin E is effective in preventing hypercholesterolemia-induced oxidative stress on the myocardium.     

Effects of platelet-activating factor on cardiovascular function,oxygen free radical status,and blood chemistry

Platelet-activating factor (PAF) is released in numerous clinical situations. PAF primes or directly activates polymorphonuclear (PMN) leukocytes, which results in release of oxyradicals (O ₂ ^– , H₂O₂, .OH) and hypochlorous acid (HOCl). The authors investigated the effects of PAF (1 µg/kg IV) in the absence and in the presence of antioxidants (superoxide dismutase [SOD], catalase [CAT], dimethylthiourea [DMTU]) and methionine, a quencher of HOCl, on cardiac function and contractility; blood lactate, gases, and pH levels; serum creatine kinase activity (CK); chemiluminescent activity of PMN leukocytes; and cardiac tissue malondialdehyde (MDA) in anesthetized dogs. Hemodynamic measurements and collection of blood samples for various biochemical measurements were made before and at various intervals up to two hours after PAF administration in the presence and absence of various antioxidants.PAF produced a decrease in indices of cardiac function and contractility and an increase in systemic and pulmonary vascular resistance. There were decreases in the blood pH and PMN leukocyte chemiluminescence and increases in blood lactate, serum CK activity, and tissue MDA content. SOD plus catalase or DMTU plus methionine reduced the effects of PAF on cardiac function and contractility, blood lactate and pH, serum CK, and cardiac tissue MDA. The antioxidants only partially antagonized the deleterious effects of PAF. The combination of SOD + CAT was superior to that of DMTU + methionine in reducing the deleterious effects of PAF.These results suggest that PAF-induced depression of cardiac function and contractility, and the increase in systemic and pulmonary vascular resistance, may be partly mediated by the release of oxyradicals and HOCl from PMN leukocytes. Antioxidants may be beneficial in reducing the deleterious effects of PAF on the cardiovascular system.     

Hemobilia caused by cytomegalovirus cholangiopathy

A 57-yr-old male on long-term steroid therapy presented with hematemesis, fever, and a retroperitoneal fluid collection. Hemobilia was diagnosed, but the cause was not identified by ERCP, computed tomography, or angiography. Peroral cholangioscopy revealed multiple biliary ulcers. Cholangioscopic biopsies diagnosed cytomegalovirus (CMV) infection. Intravenous ganciclovir therapy was initiated, and was associated with cessation of bleeding. Biliary CMV disease is rare in HIV-negative persons, but should be considered in a patient with unexplained hemobilia. Cholangioscopy may be useful for diagnosis.     

Serious complications of sulfasalazine

Whereas minor side effects of sulfasalazine are common, serious adverse reactions to this drug generally are considered rare. However, this report discusses three major complications of sulfasalazine that occurred within the past three years, one resulting in the death of a patient. As more patients with inflammatory bowel disease are being managed by physicians of various disciplines, it is important to become familiar with the potentially dangerous side effects of all medications prescribed. For this reason, a brief review of the pharmacology, clinical use, and toxicity of sulfasalazine is presented.     

Meta-analysis of arterial oxygen saturation monitoring by pulse oximetry in adults

OBJECTIVE: The purposes of the study were to: (1) describe the aggregate strength of the relationship of arterial oxygen saturation as measured by pulse oximetry with the standard of arterial blood gas analysis as measured by co-oximetry, (2) examine how various factors affect this relationship, and (3) describe an aggregate estimate of the bias and precision between oxygen saturation as measured by pulse oximetry and the standard in vitro measures.DESIGN: A meta-analysis was conducted.SAMPLE: Seventy-four studies from 1976 to 1994 met the inclusion criteria of: (1) adult study population, (2) quantitative analysis of empirical data, and (3) bivariate correlations or bias and precision estimates between pulse oximeter and co-oximeter values.RESULTS: There were a total of 169 oximeter trials on 41 oximeter models from 25 different manufacturers. Studies were conducted in various settings with a variety of subjects, with most being healthy adult volunteers. The weighted mean r, based on 39 studies (62 oximeter trials) for which the r statistic and number of data points were available, was 0.895 (var[r] = 0.014). Based on 23 studies (82 oximeter trials) for which bias and precision estimates and number of data points were available, the mean absolute bias and precision were 1.999 and 0.233, respectively. Several factors were found to affect the accuracy of pulse oximetry.CONCLUSION: Pulse oximeters were found to be accurate within 2% (± 1 SD) or 5% (± 2 SD) of in vitro oximetry in the range of 70% to 100% SaO₂. In comparing ear and finger probes, readings from finger probes were more accurate. Pulse oximeters may fail to record accurately the true SaO₂ during severe or rapid desaturation, hypotension, hypothermia, dyshemoglobinemia, and low perfusion states.     

Pulmonary vein total occlusion following catheter ablation for atrial fibrillation: clinical implications after long-term follow-up.

OBJECTIVES: We present the clinical course and management outcomes of patients with total pulmonary vein occlusion (PVO). BACKGROUND: Pulmonary vein occlusion is a rare complication that can develop after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The long term follow-up data of patients diagnosed with PVO are minimal. METHODS: Data from 18 patients with complete occlusion of at least one pulmonary vein (PV) were prospectively collected. All patients underwent RFA for AF using different strategies between September 1999 and May 2004. Pulmonary vein occlusion was diagnosed using computed tomography (CT) and later confirmed by angiography when intervention was warranted. Lung perfusion scans were performed on all patients before and after intervention. The percent stenoses of the veins draining each independent lung were added together to yield an average cumulative stenosis of the vascular cross-sectional area draining the affected lung (cumulative stenosis index [CSI]). RESULTS: The patients' symptoms had a positive correlation with the CSI (r = 0.843, p < 0.05) and a negative one with the lung perfusion (r = -0.667, p < 0.05). A CSI > or =75% correlated well with low lung perfusion (<25%; r = -0.854, p < 0.01). Patients with a CSI > or =75% appeared to improve mostly when early (r = -0.497) and repeat dilation/stenting (r = 0.0765) were performed. CONCLUSIONS: Patients with single PVO are mostly asymptomatic and should undergo routine imaging. On the other hand, patients with concomitant ipsilateral PV stenosis/PVO and a CSI > or =75% require early and, when necessary, repeated pulmonary interventions for restoration of pulmonary flow and prevention of associated lung disease.