thiobarbituric-acid and Coronary-Disease

Non-insulin-dependent diabetes mellitus (NIDDM) and hyperhomocysteinemia are both associated with increased lipid peroxidation (oxidative stress). This may contribute to the accelerated vascular disease associated with these conditions. It is not known whether the coexistence of elevated homocysteine levels will stimulate oxidative stress further than that caused by diabetes alone.. Plasma concentrations of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, were measured in patients with NIDDM who had previously had a methionine load test; some of the patients had hyperhomocysteinemia.. Plasma TBARS concentrations were elevated in diabetics with vascular disease. The additional presence of hyperhomocysteinemia was not associated with a further increase in plasma TBARS concentrations.. Lipid peroxidation is increased in patients with diabetes mellitus and macrovascular disease and is not further elevated by the coexistence of elevated homocysteine levels. It is possible that diabetes maximally stimulates oxidative stress and any further acceleration of vascular disease in patients who have coexistent hyperhomocysteinemia is mediated through mechanisms other than lipid peroxidation.

Topics: Adult; Analysis of Variance; Brain Ischemia; Carotid Artery Diseases; Case-Control Studies; Coronary Disease; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Free Radicals; Homocysteine; Humans; Hypoglycemic Agents; Insulin; Lipid Peroxidation; Male; Methionine; Middle Aged; Oxidative Stress; Peripheral Vascular Diseases; Sulfonylurea Compounds; Thiobarbiturates

Peroxidation of membrane phospholipid polyunsaturated fatty acids is considered a major mechanism of the damage occurring during post-ischemic reperfusion. The evidences in support for this mechanism of damage are based on tissue malondialdehyde (MDA) quantitation by the thiobarbituric acid test (TBA-test). In an attempt to verify this topic we have subjected isolated and Langendorff perfused rabbit hearts to a period of 60 min of severe ischemia plus 30 min of reperfusion. At appropriate time points MDA was determined in the tissue by means of TBA-test and directly by reversed phase, high pressure, liquid chromatography (HPLC). We have found no correlation between the 2 compared assays. During reperfusion, there was the formation of non-lipid related, MDA like, TBA-reactive substance which leads to overestimation of the extent of lipid peroxidation. On the contrary, by direct HPLC quantitation, there was a decrease of tissue MDA during ischemia and during the early phases of reperfusion. Our results demonstrate that TBA-test is not a reliable index of lipid peroxidation in organ systems and that MDA accumulation does not precede the evidence of the functional alterations occurring on reperfusion of the previously ischemic myocardium. These results are of relevance in the understanding of the exact mechanism of reperfusion damage as, in the same experimental model, oxy radicals have been shown to be generated and antioxidants are protective.

Topics: Animals; Chromatography, High Pressure Liquid; Colorimetry; Coronary Disease; Creatine Kinase; Indicators and Reagents; Lipid Peroxidation; Malondialdehyde; Myocardial Reperfusion; Myocardial Reperfusion Injury; Myocardium; Rabbits; Thiobarbiturates; Time Factors

Peroxidation of membrane phospholipid polyunsaturated fatty acids is considered a major mechanism of the damage occurring on reperfusion of the myocardium after a prolonged period of ischemia. The evidence in support of this mechanism of damage is based on tissue malondialdehyde quantitation by the thiobarbituric acid test (TBA test). In an attempt to verify this topic, we have subjected isolated and Langendorff-perfused rabbit hearts to a period of 60 min of severe ischemia plus 30 min of reperfusion. At appropriate time points, malondialdehyde was determined in the tissue by means of TBA test and directly by reversed-phase, high-pressure liquid chromatography (HPLC). We have found no correlation between the two compared assays. During reperfusion, there was the formation of non-lipid-related, malondialdehyde-like, TBA-reactive substance that leads to overestimation of the extent of lipid peroxidation. On the contrary, by direct HPLC quantitation, there was a decrease of tissue malondialdehyde during ischemia and during the early phases of reperfusion. Our results demonstrate that TBA test is not a reliable index of lipid peroxidation in organ systems.

Topics: Animals; Cell Membrane; Chromatography, High Pressure Liquid; Coronary Disease; Creatine Kinase; Kinetics; Lipid Peroxidation; Male; Malondialdehyde; Myocardial Reperfusion Injury; Myocardium; Phospholipids; Rabbits; Thiobarbiturates

Patients with transient ischemic attacks (TIA) were previously shown to have high plasma values of thiobarbituric acid-reactive substances (TBA-RS). To study whether these changes could be related to platelet activability, TBA-RS was investigated in 24 TIA patients before and 24 h after 1 g aspirin, an inhibitor of platelet cyclooxygenase pathway. Baseline TBA-RS values were significantly higher in TIA than in controls. Conversely, TIA patients had TBA-RS values after aspirin similar to controls, suggesting that the increase of plasma TBA-RS was not attributable to platelet hyperfunction. The evaluation of metabolic profile showed that patients with highest TBA-RS had hypercholesterolemia, hypertriglyceridemia, and/or diabetes mellitus. This study suggests that the increase of plasma TBA-RS in TIA could be an epiphenomenon of altered metabolic pathway.

Topics: Administration, Oral; Aged; Arteriosclerosis; Aspirin; Blood Glucose; Blood Platelets; Coronary Disease; Diabetes Mellitus; Female; Humans; Hypercholesterolemia; Ischemic Attack, Transient; Lipid Peroxides; Male; Middle Aged; Thiobarbiturates