• Polymer(Korea)
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• v.25 no.1
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• pp.108-114
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• 2001

Crosslinked poly(glycerol-co-malate)s were synthesized from L-malic acid in Krebs cycle and glycerol. The synthesized polymer was identified by FT-IR spectroscopy. Swelling degrees of the copolymer hydrogels were increased with an increase in pH of the aqueous solution. Hydrolytic behaviors of the crosslinked copolymers were investigated in various pH buffer solutions at 37${\circ}C$. The Hydrolysis of the copolymers proceeded faster with increasing pH of the aqueous solution. Releasing behaviors of the model drug such as diclofenac monosodium salt were also measured in various pH aqueous solutions at 37${\circ}C$. The release concentration of diclofenac monosodium salt from the hydrogel systems was increased with increasing pH. These facts indicate that the unreacted carboxyl and hydroxyl groups in the copolymers are greatly affected by pH in the conditions.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.7
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• pp.1003-1010
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• 2008

The objective of the present study was to identify differences in the expression levels of liver proteins between healthy and ketotic cows, establish a liver metabolic interrelationship of ketosis and elucidate the metabolic characteristics of the liver during ketosis. Liver samples from 8 healthy multiparous Hostein cows and 8 ketotic cows were pooled by health status and the proteins were separated by two-dimensional-electrophoresis (2D-E). Statistical analysis of gels was performed using PDQuest software 8.0. The differences in the expression levels of liver proteins (p<0.05) between ketotic and healthy cows were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF-TOF) tandem mass spectrometry. Five enzymes/proteins were identified as being differentially expressed in the livers of ketotic cows: expression of 3-hydroxyacyl-CoA dehydrogenase type-2 (HCDH), acetyl-coenzyme A acetyltransferase 2 (ACAT) and elongation factor Tu (EF-Tu) were down-regulated, whereas that of alpha-enolase and creatine kinase were up-regulated. On the basis of this evidence, it could be presumed that the decreased expression of HCDH, which is caused by high concentrations of acetyl-CoA in hepatic cells, in the livers of ketotic cows, implies reduced fatty acid ??oxidation. The resultant high concentrations of acetyl-CoA and acetoacetyl CoA would depress the level of ACAT and generate more ??hydroxybutyric acid; high concentrations of acetyl-CoA would also accelerate the Krebs Cycle and produce more ATP, which is stored as phosphocreatine, as a consequence of increased expression of creatine kinase. The low expression level of elongation factor Tu in the livers of ketotic cows indicates decreased levels of protein synthesis due to the limited availability of amino acids, because the most glucogenic amino acids sustain the glyconeogenesis pathway; thus increasing the level of alpha-enolase. Decreased protein synthesis also promotes the conversion of amino acids to oxaloacetate, which drives the Krebs Cycle under conditions of high levels of acetyl-CoA. It is concluded that the livers of ketotic cows possess high concentrations of acetyl-CoA, which through negative feedback inhibited fatty acid oxidation; show decreased fatty acid oxidation, ketogenesis and protein synthesis; and increased gluconeogenesis and energy production.

• The Korean Journal of Physiology
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• v.26 no.1
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• pp.89-97
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• 1992

In hypoxic tissue conditions, pyruvate can not enter the Krebs cycle and lactic acid, produced from pyruvate, accumulates to induce lactic acidosis. Pyruvate, However, can also be converted to alanine by glutamate pyruvate transaminase, that could be enhanced by glutamate. Therefore, it would be a fundamental measure to treat the lactic acidosis in tissue hypoxic conditions when one can convert the accumulated lactic acid, through pyruvate, to alanine. To test the above hypothesis, we induced a lactic acidosis in cats and the effect of glutamate on recovery of acid base state and removal of the lactic acid from blood were assessed and the results were compared with those of bicarbonate administration, which is one of the most frequently used conventional measure for correction of the acid base state during lactic acidosis. The results were that glutamate and combined glutamate bicarbonate solutions not only restored the acid base status completely from the lactic acidosis in an hour or two, but also restored the blood level of lactate partially. We concluded that administration of glutamate solution to convert pyruvate into alanine is effective in preventing lactic acid accumulation and treating lactic acidosis.