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Several Experimental Studies (several + experimental_studies)
Selected AbstractsInsulin treatment and cardiovascular disease; friend or foe?DIABETIC MEDICINE, Issue 2 2005A point of view Abstract Background Several observational studies have shown that higher insulin levels are associated with an increased risk of cardiovascular disease. If higher endogenous insulin levels are causally related to cardiovascular disease, one might expect an increased risk of cardiovascular disease in patients treated with insulin, as this results in high circulating insulin levels. Such risk elevation might counteract the benefits of tight glucose control. Our objective was to explore the relationship between insulin therapy and cardiovascular disease in Type 1 and Type 2 diabetes mellitus using information from available literature. Summary of comment Several experimental studies in animals and humans support the presence of a harmful effect of insulin on the vascular endothelium. In prospective follow-up studies increased insulin dosage was associated with increased risks of cardiovascular disease, although confounding by indication could not be excluded. Randomized controlled trials in diabetic patients, comparing conventional with intensive glucose-lowering treatment, although showing a reduction in microvascular disease, showed no significant difference in the incidence of cardiovascular disease. The results with respect to exposure to insulin are, however, difficult to interpret due to insufficient information on exposure to insulin levels as well as confounding by glycaemic control and body mass index. In addition, these studies were not designed to address the question whether higher insulin use relates to increased cardiovascular risk. Conclusion Published research provides conflicting evidence as to whether exposure to high levels of exogenous insulin in diabetes mellitus affects the risk of cardiovascular disease. The currently available studies have a number of serious methodological restraints that limit accurate interpretation and conclusions in this area. [source] Disc degeneration and bone density in monozygotic twins discordant for insulin-dependent diabetes mellitusJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2000T. Videman The effects of insulin-dependent diabetes mellitus on bone density and connective tissue degeneration have theoretical interest and practical relevance. Several experimental studies in animals have demonstrated the harmful effects of insulin deficiency on connective tissues. However, clinical studies in humans have produced somewhat contradictory results, most likely due to difficulties controlling for general degeneration and factors associated with diabetes. In nine pairs of monozygotic twins discordant for insulin-dependent diabetes mellitus, we compared femoral and lumbar bone mineral density (assessed by dualenergy x-ray absorptiometry) and spinal degeneration (assessed by magnetic resonance imaging). The bone densities were, on average, 0.1,0.3% lower (p = 0.87,0.96) in diabetic patients. However, after controlling for smoking, we found that the bone density in the femoral neck was 2.5% (0.025 g/cm2) lower in diabetic individuals than in their twins (p = 0.09). The five magnetic resonance imaging parameters used to evaluate discdegeneration did not differ between diabetic patients and their twins. In conclusion, our results provide no evidence that insulin-dependent diabetes mellitus has any major effect on bone density or disc degeneration. [source] Measurement of free radicals and NO by chemiluminescence to identify the reperfusion injury in renal transplantationLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2002S. Oehlschläger Abstract Oxygen free radicals are generated during the reperfusion of ischaemic organs. Several experimental studies have demonstrated that the damage produced by reperfusion can be prevented by a scavenger of free radicals. Furthermore, a significantly improved 5 year graft survival rate after cadaveric renal transplantation has been reported in patients treated with scavengers of free radicals (Land et al., 1993). Therefore, a question remains to be answered: whether a routine monitoring of the radical-mediated reperfusion injury with renal transplantation is useful, and whether there is a necessity for a generalized protective treatment in transplant patients. In a prospective trial, we evaluated a group of eight patients during and after renal cadaveric transplantation (three men, five women), using the chemiluminometric measurement of serum free radicals and NO. The serum quantities of free radicals and NO were significantly increased after reperfusion of the transplant kidney (p,<,0.02). The mean time of noticeably increased levels of serum free radicals was 4.8,±,1.2,h after reperfusion. The results thus showed an increased liberation of free radicals in the peripheral blood of transplant recipients as possible evidence of free radicals-mediated reperfusion injury in renal transplantation. The generation of free radicals measured by chemiluminescence allow a controlled therapy to decrease the generation of free radicals with antioxidants during the early transplantation period e.g. in older recipients. Copyright © 2002 John Wiley & Sons, Ltd. [source] Stability of carbon-centered radicals: Effect of functional groups on the energetics of addition of molecular oxygenJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2009James S. Wright Abstract In this paper we examine a series of hydrocarbons with structural features which cause a weakening of the CH bond. We use theoretical calculations to explore whether the carbon-centered radicals R, which are created after breaking the bond can be stabilized enough so that they resist the addition of molecular oxygen, i.e. where the reaction R, + O2 , ROO, becomes energetically unfavorable. Calculations using a B3LYP-based method provide accurate bond dissociation enthalpies (BDEs) for RH and ROO, bonds, as well as Gibbs free energy changes for the addition reaction. The data show strong correlations between ROO, and RH BDEs for a wide variety of structures. They also show an equally strong correlation between the ROO, BDE and the unpaired spin density at the site of addition. Using these data we examine the major functional group categories proposed in several experimental studies, and assess their relative importance. Finally, we combine effects to try to optimize resistance to the addition of molecular oxygen, an important factor in designing carbon-based antioxidants. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009 [source] Electrocardiographic Changes Due to Pyridoxine DeficiencyPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 5 2003EDUARDO MALMIERCA A young woman presented with marked alterations in the ECG without cardiological symptoms or evidence of structural heart disease after further evaluation. There was evidence of vitamin deficiency and the ECG normalized after 10 days of treatment with vitamins. Similar alterations have been described in several experimental studies with rats, but this is the first case reported in humans. (PACE 2003; 26:1289,1291) [source] | |||||||||||||