The Time Profile of the Effects of Moderate Hypothermia on Synaptic Acetylcholinesterase in Rat Brain.

Hypothermia in homeotherms significantly affects the neurotransmitter systems of the brain, including the cholinergic system. The function of the brain cholinergic system during prolonged moderate hypothermia is not known yet. We studied the effects of moderate hypothermia of various durations on the activity and kinetic parameters of synaptic acetylcholinesterase in rat brain.

Antioxidant Status of Rat Liver Mitochondria under Conditions of Moderate Hypothermia of Different Duration.

For evaluation of the contribution of the antioxidant system of mitochondria into the dynamics of changes in the prooxidant status, the content and activity of some of its components were studied under conditions of moderate hypothermia of varying duration. It was found that short-term hypothermia significantly increased superoxide dismutase activity and decreased the levels of low-molecular-weight antioxidants. Increasing the duration of hypothermia to 1 h led to suppression of activities of superoxide dismutase, glutathione reductase, and glutathione peroxidase and a decrease in glutathione content.

Respiratory Characteristics of Rat Liver Mitochondria Depend on the Duration of Moderate Hypothermia.

The development of pathological or compensatory-and-adaptive reactions in homoeothermic animals during various periods of hypothermia can be caused by shifts in the respiratory functions of the mitochondria. Short-term hypothermia promoted an increase in the rates of the glutamate- and succinate-dependent respiration of mitochondria. Phosphorylation rate increased as well, while oxidative phosphorylation coefficient (P/O), respiratory control, and 2,4-DNP sensitivity depended.

Thermostability of Lactate Dehydrogenase in Rat Brain under Conditions of Short-Term Moderate Hypothermia.

Thermostability of rat brain lactate dehydrogenase (LDH) was studied in intact animals and animals subjected to moderate short-term hypothermia. Two exponential stages, rapid and slow, were distinguished in the thermodenaturation kinetics. The contribution of the rapid phase to the lactate dehydrogenase denaturation kinetics was more significant: the energy of activation for this phase was 2.

A New Tellurium- and Selenoorganic Compound as an Inhibitor of Acetylcholinesterase in Brain.

We studied the effect of a new cyanine dye containing selenium and tellurium on acetylcholinesterase activity in synaptic membrane in rat brain. The cyanine dye dose-dependently inhibits activity of this enzyme, and the concentration of half-maximal inhibition of acetylcholinesterase activity was 20.46 μM.

Effect of Hypothermia on Kinetic Characteristics of Lactate Dehydrogenase in Rat Brain under Conditions of Global Ischemia and Reperfusion.

We studied activity and kinetic characteristics of lactate dehydrogenase (LDH) in rat brain under conditions of incomplete global ischemia followed by reperfusion against the background of mild hypothermia. It was found that hypothermia leads to a decrease in LDH activity in the ischemic brain; the maximum velocity of the enzyme-catalyzed activity decreased and Michaelis constant increased, due to which the efficiency of catalysis decreased to the level observed in control rats. Ischemia against the background of hypothermia was accompanied by a decrease in the inhibition constant and narrowing of effective pyruvate concentration range.

[Temperature dependence of the acetylcholinesterase activity in synaptic membranes of the rat brain].

The temperature dependence (5-40 degrees C) of the acetylcholinesterase activity in synaptic membranes of the rat brain at different substrate concentrations was studied. At low substrate concentrations, the Arrhenius plot has two linear sections. At high concentration, there is one linear section throughout the temperature range.

[Selection of optimal conditions for synthesis of protein A-laccase conjugates and their use in different variants of immunoenzyme analysis].

A study to determine optimal molar ratios of Protein A to laccase for the synthesis of their conjugate by periodate method is presented. No loss of enzymatic or immunological activity of the conjugate developed was observed during 6 month. The conjugate could be effectively used in various techniques of enzyme immunoassay (competitive or sandwich techniques, dot immunoblotting) for immunoglobulin G.

[Immunoenzyme analysis based on laccase conjugates with fluorometric detection of the enzymatic reaction product].

The possibility of using homovanillic acid as a substrate of laccase (produced by the basidiomycete Coryolus hirsutus) has been demonstrated for the first time. The reaction was shown to result in the formation of a fluorescent product. Several kinetic parameters and optimal conditions were determined for this enzymatic reaction.

[The effect of conditions of synthesis of immunolaccase conjugates on characteristics and composition of the compounds obtained].

Optimal conditions for preparing laccase conjugates by the periodate method have been selected. The effect of the initial molar ratio of IgG to laccase and pH of the medium on the composition of laccase conjugates was studied by the HPLC method. The maximum yield of the conjugates was observed, when laccase was oxidized with 0.