Biomedical subjects
Publications and source records attributed to A A Litvin.
The effect of panavir on Parkinson's syndrome induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine was studied in C57Bl/6 mice and outbred albino rats. Two injections of panavir significantly reduced the severity of oligokinesia and autonomic manifestations of experimentally induced Parkinson's syndrome.
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A mathematical model for the development of the SOS signal in nucleotide-excision repair deficient Escherichia coli cells subjected to ultraviolet light irradiation is proposed, in which regions of single-stranded DNA (gaps) are created during replication of a damaged chromosome when the strand elongation stops at pyrimidine dimers. The concentration of single-stranded DNA of gaps as a function of time is obtained. The model for the interaction of the LexA and RecA proteins, a well-established key event in SOS regulation, is presented, resulting in a system of differential equations for the concentrations of LexA, RecA and activated RecA proteins. The simulated LexA protein kinetic curves agree with the experimental data for two excision repair deficient mutants: uvrA6 and dnaC28 uvrB(del), which is also a temperature-sensitive DNA replication initiation mutant. It is shown that the model can be used to quantitatively describe the kinetics of SOS response through the amount of the SOS signal (concentration of single-stranded DNA) in a cell as a function of time.
During a 5-year follow-up of rescue party members exposed to radioactive effects of the Chernobyl accident no material changes were observed versus healthy donors in the content of calcium, cholesterol, atherogenic lipoproteins, dienic conjugates, insulin, thyroxin, triiodothyronine, thyroglobulin, IgA, IgG and fibrinogen. Inhibition of peroxidation and emergence of hypocoagulation are attributed to a reduced respiratory splash of the neutrophils. Concentrations of hydrocortisone, testosterone, IgM rose, while the activity of some antioxidant enzymes remained stable.
On the basis of examination results and treatment of 49 patients with abdominal gunshot injuries the article emphasizes that the clinical picture of gunshot peritonitis develops much faster, and the syndrome of intoxication proceeds far harder, than in cases of peritonitis with another etiology. The authors make a conclusion that an early application of extracorporal methods of detoxication (hemosorption, plasmapheresis, ultraviolet irradiation of autologous blood, xenospleen connection) could minimize the level of intoxication and contribute to the correction of the immune status.
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Using HPLC with fluorescence detector we studied elimination kinetics of the antioxidant drug mexidol and its glucuronoconjugated metabolite in 16 patients suffering from neurosis and traumatic CNS injury after receiving mexadol (in a dose of 500 mg, in tablets). It is found that mexidol undergoes rapid glucuronoconjugation and is excreted with urine (0.31% and 49.6% of the received dose in the form of mexidol and its glucuronoconjugate, respectively) within 11.5-h period of examination. A substantial variability in the rate and degree of mexidol and glucuronoconjugate elimination with urine is observed. A trend to intensive glucuronoconjugation is observed in patients aged up to 40.
Experimental study of pharmacokinetics of transdermal system with cytisin in rabbits showed a possibility of controlled intake of the drug over a 4-day period. The two stages of attaining the stationary levels of cytisin concentrations are revealed. The first stage lasted during first 24h and the second stage during succeeding 3 days. Using the data on intravenous cytisin injection we found that the stationary concentrations and the rate of cytisin intake in the first stage is twice as large as in the second stage. Thus cytisin can be classed as a short-living drug.
The new drug Bradizol (SM-345), a 2-mercaptobenzimidazole derivative producing a specific bradycardic effect, is quite rapidly eliminated upon intravenous bolus in anaesthetiezed cats. After a combined injection (bolus followed by a 60-min infusion), a constant bradizol concentration in the blood plasma is observed over a time period of 90 min. The bradizol-induced bradycardic effect and the drug concentration in the blood plasma are tightly correlated. Upon per os administration of bradizol to the experimental animals, neither the drug is detected in the blood plasma, nor the bradycardic effect is observed. It is suggested that bradizol, possessing antiarrhythmic, antifibrillator, and antiischemic properties, can be used (by intravenous injections) for the therapy of patients with diverse tachyarrhythmia geneses, including those with the ischemic heart disease.
The concentration of fenazepam in the blood plasma of rats upon application of the transdermal therapeutic system (TTS) fenapercuten was very low, incomparable to the drug concentration (recalculated to equal input doses) upon intravenous or enteral administration. Nevertheless, the TTS exhibited a pronounced anxiolytic and weak sedative action in the absence of any side myorelaxant effect. The agent responsible for adverse side effects (3-hydroxyfenazepam) was not determined in the blood plasma upon the TTS application. A steady-state concentration of fenazepam in the blood plasma of rats was observed between 2nd and 8th hours upon fenapercuten application, which agrees with the duration of anxiolytic action of the parent drug.
Problems encountered in the testing for bioequivalence of reproduced drugs (generics) are discussed in the parts incompletely resolved in domestic methodological recommendations. There are special cases when such drugs significantly vary in concentration and dosage, contain endogenous substances, exhibit intensive metabolism with a genetically polymorphous component, belong to "long-lived" compounds, and are intended for local administration. Also mentioned are problems related to insufficient sensitivity of analytical methods and some ethical aspects of investigations.
The pharmacokinetics of fenazepam upon application of the transdermal therapeutic system (TTS) fenapercuten in various forms and under different conditions was studied in rabbits. The rate of the transdermal transfer of fenazepam from TTS to blood varied from 0.76 to 2.89 mg/(ml cm2). It was found that the drug transfer rate remains constant for 2-3 days. After removal of the TTS, fenazepam is eliminated within 3 days.
The levels of the thyrotropic and thyroid hormones were studied in the serum of 115 persons going in for jogging and in 271 persons not going in for jogging, using a radioimmunoassay. Jogging was shown to cause an increase in blood T3 concentration. The author discussed the role of the thyroid hormones in the regulation of oxygen supply of tissues, shifts in water, electrolytic and carbohydrate metabolisms, and lipid levels in persons going in for jogging.
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The pharmacokinetics of baclofen was studied in the rat blood plasma and brain. The concentrations of the agent were found to be considerably lower in the brain than in the plasma. This is associated with the weakly pronounced lipophilicity of the agent in question and with the protective properties of the blood-brain barrier. Baclofen penetrates into the brain middle regions to a greater extent than into cerebral hemispheres.
When gidazepam was administered to rats in combination with 4% solutions of Tween 80 or polyvinylpyrrolidone, its bioavailability was higher than its combination with 4% polyethylene glycol 400 solution, as shown by high performance liquid chromatography. Increasing the quantities of these high-molecular compounds in gidazepam solutions was demonstrated to enhance gidazepam dealkylation in the animals after oral administration.
The pharmacokinetics of the new tranquilizer gidazepam and its desalkyl metabolite was studied in rats. Some biopharmaceutical characteristics of the agents under study were defined. Gidazepam was found to have much advantage over the principal active ingredient (desalkylgidazepam) in its higher bioavailability. The methodological approaches developed by the authors to evaluate the efficacy of gidazepam may be applied in designing novel drugs.
The biotransformation and pharmacokinetics of the new tranquilizer gidazepam were studied after its single oral administration in rats, rabbits, monkeys and man. The significant interspecies differences in gidazepam metabolism were found. Some pharmacokinetic parameters of gidazepam and its major metabolite desalkylgidazepam were determined. It was assumed that desalkylgidazepam as gidazepam in rabbits and monkeys might contribute to the formation of pharmacological effects, in rats and man its pharmacological action was realized entirely by virtue of desalkylgidazepam.