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Biomedical subjects

C J Gubler

Publications and source records attributed to C J Gubler.

At least 19 recordsLinked to original sources
PubMed1990

A potent thromboxane formation inhibitor in green tea leaves.

A ninhydrin positive compound (L2) now identified as 2-amino-5-(N-ethylcarboxyamido)-pentanoic acid, from unprocessed tea leaves was a potent inhibitor of thrombin-stimulated thromboxane formation in rabbit whole blood (Ali and Afzal; Prostaglandins, Leukotrienes and Medicine, 27: 9, 1987). In the present study, processed and unprocessed tea leaf extracts were given to rats to consume for a period of eight weeks. Cholesterol and thromboxane levels were measured in the serum obtained from clotting the blood at 37 degrees C. A significant reduction in thromboxane levels was observed in rats taking unprocessed tea extract. This reduction was equally distributed in adult as well as in juvenile rats. However no appreciable changes in the levels of thromboxane were noticed in the serum of rats taking processed tea extracts. This might be due to the presence of a labile component which is destroyed during the processing of green tea leaves. A decreased level of cholesterol was observed in rats consuming unprocessed tea extract. This decrease could be linked to the decrease in thromboxane levels as observed. Processed tea refers to commercially available tea of different brands while unprocessed tea refers to dried green tea leaves.

Amino Acids↗
PubMed1989

Effect of consumption of green and black tea on the level of various enzymes in rats.

Drinking of both green and black tea as the only liquid ingested resulted in significant decreases in the activity of transketolase in whole blood of rats both before and after the in vitro addition of thiamin diphosphate. Liver transketolase activity was decreased only by green tea. Mucosal transketolase activity was not affected by either type of tea. The activity of lactate dehydrogenase (LDH) was not affected by either type of tea, while whole blood LDH was decreased by both green and black tea. Neither tea had any affect on mucosal alkaline phosphatase, but thiamin diphosphatase activity was decreased by both teas. An increase in liver total thiamin resulted from the drinking of both types of tea.

Alkaline Phosphatase↗
PubMed1989

Effect of paraquat administered intraperitoneally on the nonpolar lipids of rabbits.

Rabbits were injected intraperitoneally with 3, 6, or 12 mg of paraquat/kg/day for a period of 3, 7, or 14 days. Rabbits receiving 3 or 6 mg of paraquat/kg/day showed a significant loss of body weight at 7 days of the treatment. Liver, kidney, heart, and lungs demonstrated a significant decrease in their weights in the first 3 days of paraquat treatment. A decrease in total lipids, total triglycerides, and total cholesterol of both liver and kidney was observed. This decrease was accompanied by a significant increase in plasma total triglycerides and total cholesterol at 7 days of paraquat treatment. The ratio of cholesterol to cholesterol esters in liver decreased after 3 days of paraquat treatment after which it showed a consistent increase until the 14th day of the paraquat treatment. In kidney, this ratio increased for up to 7 days of paraquat treatment followed by a decrease at the 14th day. These results indicate, contrary to earlier reports, that rabbits are susceptible to paraquat toxicity.

Animals↗
PubMed1988

Isolation of transketolase from rabbit liver and comparison of some of its kinetic properties with transketolase from other sources.

1. Rabbit liver transketolase activity was purified 56-fold using the following steps: ammonium sulfate precipitation, chromatography on DEAE-Sephadex A-25, concentration through an Amicon ultrafiltration cell and rechromatography on DEAE-Sephadex A-25. 2. The enzyme showed an optimum PH for activity at 7.8-8.0. 3. The optimum temperature was around 40 degrees C and the activation energy calculated from the Arrhenius plot was found to be 11.4 kcal/mole. 4. The molecular weight of the enzyme, as determined by gel filtration, was found to be approximately 162,000, while the content of thiamin diphosphate was between 1.8 and 2 mumole per mole protein. 5. Addition of thiamin diphosphate and magnesium chloride did not influence the activity. 6. From the kinetic studies of the enzyme, the Km values for xylulose-5-phosphate, ribose-5-phosphate and fructose-6-phosphate were 3.8 x 10(-5) M, 9.5 x 10(-5) M and 1.1 x 10(-2) M, respectively.

Animals↗
PubMed1988

Isolation of transketolase from human erythrocytes.

Transketolase was isolated from human red blood cells with over 6,200 fold purification by a new method. The stepwise procedure for the isolation of the enzyme from erythrocyte hemolysate included the use of ethanol/chloroform precipitation, chromatography on hydroxyapatite and finally, affinity adsorption on carboxymethyl-cellulose. The molecular weight of erythrocyte transketolase, as determined by polyacrylamide gel electrophoresis, appeared to be about 140,000. The pH optimum for activity was between 7.6 and 7.8 and the optimum temperature for activity was 50 degrees C. The Km values for xylulose-5-phosphate, ribose-5-phosphate and fructose-6-phosphate were 2.0 x 10(-4) M, 3.2 x 10(-4) M and 2.0 x 10(-3) M, respectively.

Chromatography, Ion Exchange↗
PubMed1987

Prostaglandin associated mortality following intravenous injection of catfish epidermal secretions in rabbits.

Toxicity of soluble protein extracts from epidermal gel secretions of the catfish, Arius thalassinus, was examined in rabbits. Intravenous injections containing doses as low as 2 mg protein/kg body weight caused mortality in all animals tested. An increase in plasma levels of thromboxane B2 (TXB2) and of 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) were observed following injections. Both the mortality and prostaglandin release were prevented by pretreatment of rabbits with either indomethacin or hydrocortisone. A similar indomethacin sensitive induction of prostaglandin release was noted following the in vitro treatment of arterial tissue sections with gel. Lethality appears to result from gel substances stimulating phospholipase activity to yield arachidonic acid, which is then metabolized to give toxic levels of prostaglandins.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

A comparison of transketolase assay and transketolase and lactate dehydrogenase activity levels in whole blood and red cell hemolysates and in leukocytes.

1. A study was made of transketolase activity in red and white blood cells and of conditions for assay for transketolase activity and for assessment of the "TPP effect" in human and rat blood. 2. The ratio of the transketolase activity in white cells to that in red cells varied between 23 and 93. 3. Red cells or white cells can both be used for assessment of transketolase activity and the "TPP effect", but the best source for evaluation of transketolase activity and the percent change on addition of thiamin diphosphate appears to be whole blood.

Animals↗
PubMed1985

Toxic effects of the soluble skin secretion from the Arabian Gulf catfish (Arius thallasinus, Ruppell) on plasma and liver enzyme levels.

Injection of skin toxin into the marginal ear vein of rabbits resulted in acute respiratory distress and convulsive movements, followed by death within 7 min. Significant increases in total plasma lactate dehydrogenase and the hepatic and cardiac derived isozymes and in glutamic-oxaloacetic and glutamic-pyruvic transaminase activities were observed in animals receiving toxin. Lower doses of toxin increase the survival time and enzyme levels in plasma. Skin toxin produces a time dependent toxic effect on the liver and heart.

Alanine Transaminase↗
PubMed1984

Toxicity of flavoglaucin from Aspergillus chevalieri in rabbits.

Female rabbits were injected intraperitoneally (i.p.) with purified flavoglaucin from Aspergillus chevalieri. After 2 h the rabbits were bled and the livers removed for enzyme assays. No changes were found for plasma lactate dehydrogenase (LDH) and its isozymes or liver transketolase (TK) activities. A small but not statistically significant increase was found in plasma glutamate pyruvate transaminase activity. A highly significant increase in plasma glutamic oxaloacetate transaminase activity was observed along with an increase in liver LDH which was, however, not quite significant. The liver also showed some histological evidence of hepatic damage.

Alanine Transaminase↗
PubMed1982

Effects of treatment with thiamin antagonists, oxythiamin and pyrithiamin and of thiamin excess of the levels and distribution of thiamin in rat tissues.

Levels of thiamin and its derivatives in brain, heart and liver were determined in control, thiamin-deficient, pyrithiamin-treated and oxythiamin-treated rats at various times after the start of treatment. With 10 micrograms of thiamin/100 g/day subcutaneously, rats rapidly lost thiamin from the tissues until growth maintenance levels were reached. Oxythiamin had a minimal further effect on tissue thiamin while pyrithiamin caused further marked reduction. With higher levels of thiamin intake, tissue thiamin levels increased with intakes of up to 150-200 micrograms/100 g/day after which they did not show any further significant increase. Levels of pyrithiamin above 50 microgram/100 g/day for 20 days had only minimal further effect upon tissue thiamin levels over that with 50 micrograms.

Animals↗
PubMed1980

Biological activity of 1,N6-ethenothiamin, a fluorescent analog of thiamin, in rats.

The ability of the recently synthesized fluorescent analog of thiamin, 1,N6-ethenothiamin, to substitute for thiamin in rats in vivo has been studied. 50 micrograms of ethenothiamin/100 g body weight/day injected in rats allowed about one-half the weight gain with 50 micrograms/100g/day of thiamin. The activities of the pyruvate and alpha-keto-glutarate dehydrogenases of liver mitochondria were partially restored by 50 micrograms/100g/day of ethenothiamin. Ethenothiamin at this level did not appear to restore the branched-chain alpha-keto acid dehydrogenase activities to any extent. When 150 micrograms of ethenothiamin/100g body weight/day was injected, growth was optimum, but these enzyme activities still did not achieve normal levels.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗