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Biomedical subjects

K Barna

Publications and source records attributed to K Barna.

At least 19 recordsLinked to original sources
PubMed1991

[Peroxidative effects of tetracycline antibiotics].

After six-day administration of rolitetracycline (RTC) in the cardiac mitochondria of old rabbits the rate of oxygen consumption (glutamate-malate as well as 2-oxoglutarate) declines, while the malonic dialdehyde (MDA) rises. This provides evidence of more intense lipoperoxidation due to rolitetracycline. However, the ATP-ase activity increases and therefore this parameter is unsuitable in this experimental set-up (presence of tetracycline antibiotic) as an indicator of impaired integrity of mitochondrial membranes. After administration of RTC the activity of superoxide dismutase (SOD) increases markedly, but in case of concurrent administration of vitamin E it declines which is evidence of the prooxidative action of tetracyclines. Tetracycline itself and its metabolites which are formed during the biotransformation and degradation of epianhydrotetracycline (ETC) do not alter significantly the oxygen consumption nor the ATP-ase activity in cardiac mitochondria of old rabbits in vitro. Of these metabolites only anhydrotetracycline (ATC) and in particular epianhydrotetracycline (EATC) inhibit both parameters. From experiments in vitro ensues the relationship between the action and structure of the antibiotic and its metabolites the structure of cycle C and the nature of the substituents in positions C6 and C1 of this tetracycline cycle, as prerequisites are created for the formation of prooxidative structures.

Aging↗
PubMed1991

[The effect of tetracycline and vitamin E on energy metabolism in cardiac mitochondria of old rabbits pretreated with isoproterenol].

The possibility of eliminating adverse effects of tetracycline and isoproterenol pretreatment on energy generation of myocardial mitochondria by vitamin E administration was investigated in old rabbits. Vitamin E administered in doses of 1.5 mg per kg body weight over 6 days was found to improve energy metabolism in old rabbits whose metabolism had been deranged by isoproterenol pretreatment in the dose of 1.5 mg per kg body weight. Subsequent administration of vitamin E to rabbits pretreated with isoproterenol and tetracycline in doses of 15 mg per kg body weight daily over 6 days also resulted in improvement of energy metabolism parameters studied. Under the given conditions vitamin E was found to exert a protective effect on oxidative phosphorylation of the myocardium damaged by isoproterenol and tetracycline.

Adenine Nucleotides↗
PubMed1979

Cellular immune responses and lymphocyte populations in chronic hepatitis.

Cellular immune responsiveness was examined in chronic persistent hepatitis, chronic active hepatitis and alcoholic liver disease by the use of the lymphocyte transformation test in response to PHA and to allogenic liver mitochondria, inhibition of leukocyte migration, delayed-type skin tests and non-immunospecific granulocyte function tests. Lymphocyte markers, E and EAC rosette forming cells were used for the study of lymphocyte populations. The results have confirmed that the T-cell borne cell-mediated immune function is impaired in chronic active hepatitis, as also in a number of cases of chronic persistent hepatitis.

Adolescent↗
PubMed1979

[Chemical and biological properties of a fluorescence derivative of gentamycin].

By reaction with 4-phenylspiro[furan-2(3H),1'-phthalan]-3,3'-dione a fluorescing gentamycin derivative was produced which is characterized by the following properties: High fluorescence intensity in UV light, which enables simple and sensitive determination up to 10(-9) M. In this way it is possible to determine the localization of this substance in tissues, cells and body fluids. When favorably stored, the derivative is chemically stable. At pH 8 and storage at +5 degrees C in the dark for 27 days the substance loses only 5% of its original fluorescence. In comparison with the nonsubstituted gentamyzin the derivative has a twofold higher binding capacity to serum albumin. The antimicrobial properties are retained; the range of antimicrobial effects is similar to that of gentamycin.

Bacteria↗
PubMed1978

Fluorescent analogue of ampicillin.

As the outcome of the reaction of ampicillin with 4-phenylspiro[furan-2(3H),1'-phthalane]-3,3'-dione (fluorescamine), the chemical analogue of ampicillin (F-AMPI) has been prepared. This preparation has manifested strong fluorescence in UV light. Some basic chemical and biological properties of this product such as chemical stability electrophoretic mobility, uniformity during thin-layer chromatography and ion-exchange chromatography, and antimicrobial activity were examined. The results were compared with values of the original antibiotic.

Ampicillin↗
PubMed1977

Chronic active hepatitis in patients with and without hepatitis B surface antigenemia.

This study was designed to compare the clinical and immunological characteristics of the hepatitis B surface antigen (HBsAg)-positive and HBsAg-negative (cryptogenic) forms of chronic active hepatitis. The data of 48 patients with chronic active hepatitis, 24 with persistent HBs antigenemia and 24 without HBsAg, were analysed. HBsAg was detected by counter-immunoelectrophoresis and radioimmunoassay. The clinical features, biochemical liver function tests, immunoglobulins, complement C3, antoantibodies, and cell-mediated immunoreactivity of the two forms of the disease were compared. Cirrhosis was found to occur more frequently at the time of diagnosis in the HBsAg-negative group, and the serum alkaline phosphatase level was raised significantly compared to the HBsAg-positive form. The elevation of the IgG level was greater in the cryptogenic form, but the difference was not statistically significant compared to the HBsAg-positive patients. There was a marked difference in the frequency of the mitochondrial antibodies, but not of the antinuclear factor and other autoantibody-like serum factors. Lymphoblastic transformation revealed a similar diminution in response to phytohaemagglutinin stimulation in both groups of patients compared to the normal controls. An increase of the 3H-thymidine incorporation was seen after stimulation with human liver mitochondrial antigen, and leukocyte migration inhibition could be observed with this antigen in both forms of chronic active hepatitis.

Adolescent↗
PubMed1977

Detection of hepatitis B surface antigen in isolated hepatocytes.

HBsAg was detected by indirect immunofluorescent method in liver biopsy specimens of 60 symptom-free HBsAg positive volunteers. An effort was made to separate from the material intact cells suitable for studying HBsAg localization in the liver cells.

Fluorescent Antibody Technique↗
PubMed1977

[Effect of chlortetracycline on the peptide spectrum of rat serum].

Application of chlortetracycline in rats resulted in the occurence of certain peptides in the blood-serum, which could not be detected in the serum of an untreated control group. These results were obtained by means of high voltage electrophoresis and paper electrophoresis of the serum of rats which was analyzed 1,3, and 13 hours respectively after a single dose of 50 mg chlortetracycline per 100 g body weight in comparison to an untreated control group. The new peptides could be found in the slight alkaline range 1 and 3 hours after application of chlortetracycline and in the strong acidic area of the electrochromatogram 13 hours thereafter. A more detailed investigation of the new peptides could demonstrate that the number of the following amino acids was reduced in the peptide chains after chlortetracycline: leucine, valine, serine, arginine, and lysine. On the other hand, amino acids, such as citrulline, sarcosine, alpha-aminobutyric acid, and ornithine, could be found which are normally not present in proteins.

Amino Acids↗