[Recent data about the LDL-atherogenesis relationship]. / Date recente asupra relatiei LDL-aterogeneza.

The steps în pathophysiology of ATS make easier the understanding of waves of processes that lead to the disfunction of the endothelial cells, hypertrophy of the arterial wall and în the end to the complication which drawn from this process. Atherogenic process which is characterised by proaterofenethic and atherogenetic mechanism imbalance suppose three phases: early, transition and terminal phase. The initial phase involve the focal influx and LDL-cholesterol accumulation în the arterial intima, the ROS (reactive oxygen species) and azot generation by smooth muscular cells, macrophages and endothelial cells and oxidative modification of LDL. Scientific data revealed that LDL oxidation is mediated by peroxinitrite (ONOO) anion which could act directly over the thiol groups or indirectly through OH and NO radicals from peroxinitrous acid breakdown and who initiate the polyunsaturated fatty acids peroxidation and the oxidation of apolipoprotein B-100. LDL completely oxidated are recognised by scavenger receptors which are not regulated by up and down regulation. The last event of the early atherogenic process is the formation of foam cells from macrophages through LDL modified captation by scavenger receptors.

Influence of light-dark cycle alteration on free radical level in rat cns.

The experiment analysed the evolution of several redox parameters caused by light-dark cycle alteration in different rat brain segments: cortex, brain stem, diencephalon. Continuous light (L:L) enhanced SOD, CAT, GPX and GSH levels to different extents in the various central nervous system regions investigated, depending on the entrainment period: 24 h, 48 h, 72 h, 7 days. Continuous darkness (D:D -24 h, 48 h, 72 h, 7 days) generally diminished SOD, CAT and GSH values, but increased GPX at 48 h and CAT at 72 h. MDA levels were higher in D:D, too. After 7 days L:L or D:D redox indices tended to reach the normal range again. Redox system spatio-temporal versatility and complementarity suggested the existence of a possible biochemical radical cell clock gear.

[The effect of the combination of vitamin E and C on the oxidative stress parameters in physical exercise]. / Cercetari privind efectul cuplului de vitamine E si C asupra unor parametri de stres oxidativ în exercitiul fizic.

The paper outlines the modification of some antioxidant enzymes and of reduced glutathione studied on physical training induced oxidative stress model. We also assessed vitamin E and C effect. Biochemical determinations were performed on heart homogenate and erythrocytes. Catalase and glutathione peroxidase activity diminished and superoxide dismutase activity increased to a different extent in both tissue samples, while coupled vitamin E and C protection to these tissues equally varied. The glutathione (GSH) pool decreased in erythrocytes and was moderately enhanced in the heart. Either in red blood cells or heart tissue GSH level constancy was maintained by simultaneous administration of vitamins through the experiment (training period). Malondialdehyde concentration revealed a slightly pro-oxidative behaviour of this couple of vitamins that explained the only partial recovery of enzymatic activity to normal values as well as a moderate lipid peroxidation process. Both phenomena were better expressed in erythrocytes.

[The reduction of dyslipidemia and oxidative stress in experimental diabetes mellitus treated with probucol]. / Reducerera dislipidemiei si a stressului oxidativ în diabetul zaharat experimental tratat cu probucol.

There is considerable controversy regarding the role of oxidative stress in development of macro and microangiopathy in diabetes--a free radical associated disease. Increasing the oxidative glycosylation of plasma lipoproteins by reactive oxygen species (ROS) and reduction of scavenging system under conditions of hyperglycemia may accelerate diabetic vascular disease. We have investigated the effect of Probucol (P) a drug with strong lipophilic radical scavenger action, on plasma lipoproteins variations, malondialdehid (MDA) production, atherosclerotic index (total Cholesterol/HDL Cholesterol), glycemia and glucosuria in Wistar male alloxanic rats with/without enriched cholesterol diet. The inhibition of lipoproteins oxidation, resulting from diminishing MDA, in our study, would furthermore delay the absorption and penetration of lipids and lipoproteins into deeper vascular layers and thereby reduce the risk of atherosclerotic vascular lesion. Our result suggest that treatment with inhibitors of lipoproteins oxidation may reduce the risk of cardiovascular complications in diabetes.

Direct detection of the antioxidant activity of a new flavonic derivative using the chemiluminescence method.

The antioxidant potential of a new water soluble flavonic derivative, namely theophylline rutoside (TR-1722) has been tested using the chemiluminescence method. The method is based on the oxidative degradation of luminol by the hydrogen peroxide in Tris-HCl-buffer, when reactive species of oxygen are being obtained: O2-., HO., 1O2, and allows for the capability of substances to inhibit the free radical processes in this test system to be quantified and hence for their antioxidant properties in respect to a standard substance (in our case quercetin) to be compared. The results obtained reveal that TR-1722 has antioxidant action comparable to that of quercetin, the highest efficacity being registered at the concentration of 2 mumol/l, the conditions being: H2O2 16,2 mmol/l; luminol 2 mumol/l, in Tris-HCl buffer 20 mmol/l, pH 8.3. The antioxidant potential of TR-1722 is also maintained when the conditions of the system are modified, that is, the concentration of the hydrogen peroxide, the intensity of the action being dependent on the hydrogen peroxide concentration, but no direct proportionality is registered.

Antioxidant action of a new flavonic derivative in acute carbon tetrachloride intoxication.

The antioxidant potential of a new flavonic derivative named conventionally theophylline-rutoside [TR-1722] was estimated by the measurement of G-6-Pase activity (marker enzyme for the endoplasmic reticulum), catalase activity (enzyme involved in the antioxidant defence process), and total -SH groups from the hepatic homogenate, using CCl4 as a free radical generating model. To show changes in the permeability of the hepatocyte membrane, the activity of lactate dehydrogenase (LDH) in plasma was determined. The obtained results suggest that TR-1722 acts by curtailing both lipid peroxidation and alkylation processes.

The relation zinc-lipidic peroxidation in experimental diabetes mellitus.

The authors investigated the influence of Zn upon glycemy and certain REDOX parametres within the hepatic tissue. The experiment was performed on young Wistar rats with AD, to which Zn sulfate was administered. The values of the antioxidating enzymes: cathalasis and peroxidase decrease in the diabetes' hepatic tissue. The therapy with Zn remakes their activities and increases glutathione synthesis. The Zn protecting effect in lipidic peroxidating process also acts upon hepatocyte membrane, fact illustrated by the decrease of LDH in the plasma of the animals treated with Zn.

[The effect of the ascorbic acid-Cu (II) couple on enzyme activity]. / Efectul cuplului acid-ascorbic-Cu (II) asupra activitatii unor enzime.

Ascorbic acid (AA), Cu (II) and their association affect in different ways the activity of G6P-ase and G6PDH from the rat hepatic cytoplasm enriched in microsomes. G6P-ase is inhibited at a wide range of concentrations: 200-2 mM AA and 1-0.1 mM Cu (II). The association AA-Cu in the above mentioned concentrations, proved to be a stronger inhibitor than AA or Cu (II) introduced separately in the incubation medium. The activity of G6PDH is stimulated by AA-Cu (II) association and inhibited by AA in the dialyzed and nondialyzed cytoplasm. Cu (II) inhibits the activity of G6PDH in the nondialyzed cytoplasm and stimulates it following dialysis. The compounds with recognized antiradical action prove to be inefficient in restoring the activity of G6PDH affected by the AA-Cu (II) association.