Structural and Functional State of Erythrocyte Membranes in Mice at Different Stages of Experimental Parkinson's Disease Induced by Administration of 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP).

We studied some structural and functional parameters of erythrocyte membranes in mice at the late presymptomatic and early symptomatic stages of experimental Parkinson's disease induced by administration of MPTP (hemolysis, microviscosity of different regions of the lipid bilayer, LPO intensity, activity of antioxidant enzymes, and kinetic properties of acetylcholinesterase). At the presymptomatic stage, significant deviations of the studied parameters from the normal were observed; they were similar in direction and magnitude to those in humans with Parkinson's disease. At the early symptomatic stage, most parameters tended to normal. Microviscosity of bulk lipids increased at the presymptomatic stage and decreased after appearance of clinical symptoms. This dynamics probably reflects activation of compensatory mechanisms aimed at inhibition of oxidative stress triggered by the development of the pathological process.

[Membrane structure markers and the acetylcholinesterase activity of erythrocytes in patients with mild cognitive impairment].

Patients with the syndrome of MCI (n=22) and a control group (31 people without signs of mental and neurological diseases) were tested for the degree of hemolysis of erythrocytes (RBC), (membrane structure markers, acetylcholinesterase (AChE) activity in RBC), the level of lipid peroxidation (LPO) (content of malondialdehyde - MDA), microviscosity of surface areas of the membrane using two spin probes localized in the bulk lipids (s1) and in adjacent to the proteins regions of lipid bilayer (s2). There was no difference between the level of spontaneous hemolysis in the group with MCI and the control group which indicated the absence of changes in the mechanical resistance of the RBC membrane. Significant between- group differences were identified for s2 (the increase by >40% in MCI). A trend toward the increase in MDA level in MCI was found as well. There was a decrease by approx. 30% in the Vmax and Km for AChE reaction that indicated the changes in properties or amount of this enzyme. The value of Vmax/Km that determined the real activity of AChE was similar in both groups. No correlations between parameters of membrane structural-functional state that are characteristic of normalcy were noted in the patients with MCI. This finding demonstrated the changes in structural-functional regulation in RBC membrane in elderly people with MCI. Membrane structure status of erythrocytes in MCI holds a special position and differs both from normal ageing and developed Alzheimer's disease. The s1/s2 ratio is recommended as a membrane "marker"for identification of MCI.

[Oxazole derivatives as compounds modifying radiation effects in the body of mice].

A new class of substances exhibiting radioprotective and radiosensitizing effects depending on the concentration of the substance has been found. The radioprotective effect is probably due to the resonant absorption of radiation energy and its transformation into low-energy forms, as well as reactions with water radiolysis products. We studied the effects of 2,5-difeniloxazole and di[2-(5-feniloxazolil)]benzene in various concentrations in conjunction with irradiation on the growth of melanoma B-16 in mice and the average time of their lives. When using individual doses of irradiation and doses of preparations, we observed an increase in the average lifetime of mice and a reduced tumor size. These data allow us to conclude about the possibility of using these substances in the radiotherapy of tumors.

Phenazepam in therapeutic and ultralow doses in vitro modulates the content of lipid peroxidation products and acetylcholinesterase activity in membrane fraction from mouse brain.

In vitro incorporation of tranquilizer phenazepam in a concentration of 10(-13) M into membrane fraction from mouse brain produced a prooxidant effect. In concentrations of 10(-5)-10(-9) and 10(-15)-10(-17) M this agent possessed antioxidant activity. Phenazepam significantly decreased the maximum rate of enzymatic reactions (10(-5) and 10(-15) M) and Michaelis constant (10(-5) M) for acetylcholinesterase. Incorporation of phenazepam in ultralow doses into membrane modified its lipid components (estimated by lipid peroxidation) and functional state, and this effect was comparable with the influence of this substance in standard doses. This probably contributes to the physiological effect of ultralow doses of phenazepam in.

[The influence of pharmacologically active substances of different classes at ultra low doses on lipid peroxidation in brain cell membranes and activity of acetylcholinesterase in vivo and in vitro]. / Vliianie farmakologicheski aktivnykh veshchestv raznykh klassov v ul'tramalykh dozakh na peroksidnoe okislenie lipidov v kletochnykh membranakh golovnogo mozga i aktivnost' atsetilkholinésterazy in vivo i in vitro.

One of the approaches to the development of new medicines now is the exploration of the effects of low and ultra low doses (ULD) of biologically active substances and preparations traditionally used in rather high dosages. The purpose of our work was to investigate the influence of pharmacologically active substances of various classes at wide range of concentrations, including ultra low, on lipid peroxidation in cell membranes of mice brain and activity of acetylcholinesterase (AChE). The action of synthetic antioxidant (AO) from the group of hindered phenols (inhibitors of free-radical reactions) phenozan, neurotransmitter acetylcholine (ACh), hybrid compound "phenozan + ACh + alkyl radical C-10" (perspective for Alzheimer's disease therapy), tranquilizer from benzodiazepines phenazepam and hydrogen peroxide were investigated. The influence of the investigated substances at ULD (concentrations) on kinetic parameters of the reaction, catalysed with soluble and membrane AChE (Michaelis constant and maximal velocity), and also on lipid peroxidation (LPO) system (level of products and LPO velocity, contents of total lipids, phospholipids, cholesterol) in mice brain cell membranes in vitro and in vivo was revealed. Concentrational and dose curves were of compilated character with the presence of zero effect zones typical for the agents capable to work at ULD. The effects of super low and "usual" doses of investigated substances were commensurable.

[The characteristics of the biological action of low doses of irradiation]. / Osobennosti biologicheskogo deistviia malykh doz oblucheniia.

Biochemical, biophysical and functional properties of the genetic and membrane apparatus of the cell were considered activity and regulatory properties of the membrane and cytosolic enzymes of organs and tissues of mice exposed to radiation in the wide range of doses of 6 to 1800 mGy with the radiation intensity of 4.1 x 10(-3) and 41 x 10(-3) mGy/min. It was shown that the dose-dependence of changes in the investigated properties is of non-linear polymodal (bimodal) nature. The value of the maximum and the dose at which the latter was observed depend on the object's nature, radiation intensity and time passed after irradiation. An essential factor is that sensitivity of molecules, cells, organs and animals exposed to low-dose radiation to other damaging effects changes. The explanation is given in terms of the changes in the relation between the quantity of damages and the activity of reparation systems induced by low-dose irradiation.

[The biochemical changes in the brain synaptosomes during the gamma irradiation of mice at a low dose with different intensities]. / Biokhimicheskie izmeneniia v sinaptosomakh golovnogo mozga pri gamma-obluchenii myshei maloi dozoi s raznoi intensivnost'iu.

Some characteristics of mice brain nerve-endings' lipid phase were studied (total lipids, total and individual phospholipids and cholesterol contents, their ratios, lipid peroxidation level, rigidity index) after single low dose, whole body gamma-irradiation (15 cGy) with dose intensities of 0.01, 0.25, 9.0 cGy/min. Some markedly expressed alterations were found out in those parameters. Brain membranes functioning also changed significantly as it was judged by membrane-bound acetylcholinesterase activity. All the changes revealed complicated dependence both on dose intensity and on time period after irradiation. The ranges of the observed changes suppose CNS state to have been modified by low dose irradiation including CNS sensibility to external psycho- and neurotrophic factors.

[Synthetic bioantioxidants--inhibitors of acetylcholinesterase activity]. / Sinteticheskie bioantioksidanty--ingibitory atsetilkholinésteraznoi aktivnosti.

The inhibitory effects of synthetic antioxidants (3-oxypyridine, pyrimidine and hindered phenols) on the enzymic activity of membrane-bound acetylcholinesterase (AChE) was studied. In terms of estimated kinetic characteristics of AChE-reaction (KM, Vmax, KI), the pattern of enzyme inhibition by the hindered phenol compounds was found to be of non-competitive or mixed type depending on the inhibitor structure or on the substrate acetylcholine or acetylthiocholine used. The comparative study of the inhibitory action of water-soluble derivatives of hindered phenols and fatty-soluble ionol made it possible to reveal possible contributions to the inhibition of both direct and mediated (by the membrane microsurroundings) effects on the membrane-bound AChE by the studied synthetic bioantioxidants.

[The role of changes in the antioxidative activity and phospholipid composition of the rat liver in the mechanism of phenazepam action on the liver and the protective effect of talamonal]. / O roli izmenenii antiokislitel'noi aktivnosti i sostava fosfolipidov pecheni krys v mekhanizme deistviia fenazepama na pechen' i zashchitnom éffekte talamonala.

Phenazepame exhibited properties of prooxidant in a model system of oleic acid methyl ester oxidation. After single intraperitoneal administration of phenazepame (5 mg/kg) the antioxidative activity (AOA) of rat liver lipids was decreased, correlating with level of histidase and urokinase activity in blood plasma indicating the liver tissue injury. Distinct alterations in the relative content of liver phospholipids were also noted. A phase type of alterations was observed in the content of these phospholipids as well as in the ratio phosphatidyl choline/phosphatidyl ethanolamine; at the same time, the phospholipid ratio was altered simultaneously with the alterations of the enzymatic activities in blood. After administration of the antioxidant, which normalized the AOA level and the phospholipid composition, activities of histidase and urokinase were markedly decreased in blood. The neuroleptanalgetic drug thalamonale, protecting liver tissue against the impairments, normalized the AOA level and the phospholipid composition. Thus, alterations in AOA and in the phospholipid composition reflected distinctly the unfavourable effect of phenazepame as well as the protecting action of thalamonale on liver tissue.

[Changes in external membrane lipids of the mouse liver mitochondria and kinetic parameters of membrane-bound monoaminoxidase in vivo and in vitro]. / Modifikatsiia lipidov naruzhnoi membrany mitokhondrii pecheni myshei i kineticheskikh parametrov membranosviazannoi monoaminoksidazy in vivo i in vitro.

Influence of lipids on monoamine oxidase (MAO) activity in external mitochondrial membranes of mice liver cells was studied. Content of acidic phospholipids (phosphatidyl serine + phosphatidyl inositol) correlated with Km value of tyramine deamination. The data obtained suggest that these phospholipids are important for the surface membrane charge which determines MAO affinity to the substrate. Relationship was also found between the viscosity of lipid components and Km, Vmax and the rate of inhibition by an excess of the substrate. Thus, the structural state of membrane lipid components affects the MAO affinity to the substrate, catalytic activity of the enzyme and its sensitivity to regulatory effectors. Among the kinetic patterns maximal rate, i.e. catalytic activity of the enzyme, was distinctly dependent on the viscosity of lipid bilayer.

[Alteration of the permeability and composition of liver cell lysosomal membranes after a thermal burn]. / Izmeneniia pronitsaemosti i sostava lizosomal'nykh membran kletok pecheni posle termicheskogo ozhoga.

Rat hepatocyte fractions enriched with lysosomes were studied one hour and 7 days after vast thermal burn of the skin. The ratio of free catepsine D activity to its total activity served as an index of lysosomal membrane resistance. The lipid composition was assayed by thin layer chromatography on silica gel. Material increase in lysosomal membrane permeability was recorded both one hour and 7 days after burn. Significant shifts were also seen in the composition of neutral lipids and phospholipids. Burn gave rise to the triglyceride fraction that was not present in the control. Among phospholipids the most labile were minor fractions, that is those of sphyngomyelin, phosphatidylinosite and phosphatidylserine. The changes in the lipids are considered as essential for destructive alterations in the liver in burn disease.

[Change in the antioxidizing activity of the lipids during aging]. / Izmenenie antiokisliter'noi aktivnosti lipidov pri starenii

Antioxidative activity (AOA) of lipids in mice liver was decreased in the old animals. The rate of the AOA decrease varied in different strains of mice. Alteration in the AOA is a phenomenon typical, but unspecific, for the senescence process. Senescence belongs to the pathological states, which occur at the decreased level of the AOA. Similar alterations in AOA were noted in radiation disease, stress state, hyperoxia, intoxications. Development of these pathological states could be inhibited or prevented by means of substances, increasing the antioxidative activity. At the same time the substances, known as inhibitors of senescence, were shown to increase the AOA in vivo. The effect of substances on the antioxidative activity of lipids is considered as a useful test for selection of agents, which appear promising as drugs for prolongation of survival periods.