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PubMedDate not supplied

[The state of the microsomal oxidative system of the rat liver in the postoperative period].

A functional state of microsomal enzymatic system was studied in liver tissue of rats within 24, 48 and 72 hrs after surgical operation. Factors of operational treatment and of postoperational period were shown to inhibit distinctly amidopyrine demethylase as well as to decrease the content of cytochromes P-450 and b5 and the glycogen concentration in liver tissue. Content of lactic and pyruvic acids was increased in blood. Depression of the functional state of liver microsomes, occurred as a result of hypoxia, appears to be responsible for the phenomenon of elevated drug toxicity during postoperational period.

Anesthesia, Inhalation↗
PubMed1998

Restoration of rat liver L-threonine dehydratase activity by pyridoxamine 5'-phosphate: the half-transaminating activity of L-threonine dehydratase and its regulatory role.

When a highly purified preparation of rat liver l-threonine deaminase (l-TDH, EC 4.2.1.16) was 99% inactivated by dialysis, removing bound pyridoxal 5'-phosphate (PLP), the apoenzyme was reactivated not only by PLP but also by pyridoxamine 5'-phosphate (PMP). When purified by HPLC, the commercial PMP used in the incubation mixture was found to contain only extremely small amounts of PLP, which could not account for restoration of l-threonine dehydratase activity. HPLC analysis of the assay mixtures showed that during incubation, sufficient PLP had been formed for reactivation of the apoenzyme. The apoenzyme evidently bound PMP and triggered transamination between PMP and the keto acids, which either contaminated, or were formed by the minimal amount of PLP-holoenzyme always present even in the dialyzed preparation. When sufficient PLP was formed, the PLP-holoenzyme and the original 'true' l-threonine dehydratase activity were restored. When PMP was incubated with the apoenzyme in the presence of small quantities of keto acids (pyruvate or 2-oxobutyrate) small amounts of l-alanine or l-aminobutyrate were formed. The reaction was not reversible; l-alanine and l-aminobutyrate did not react with the PLP-holoenzyme. No transaminating activity occurred with other amino acids. These results show that l-threonine dehydratase exists in two forms: the well known stable apoenzyme-PLP (hydrolase deaminating) and the transient apoenzyme-PMP (non-reversible half-transaminating). Half-transamination has the biological role of keeping the activity of the 'true' l-TDH constant and of regulating intracellular levels of pyruvate, alanine, oxobutyric acid, l-aminobutyric acid, l-threonine and l-serine.

Acetoacetates↗
PubMedDate not supplied

Effects of glucose, vitamins, and DO concentrations on pyruvate fermentation using Torulopsis glabrata IFO 0005 with metabolic flux analysis.

The effects of glucose, vitamins, and DO concentrations on efficient pyruvic acid fermentation were investigated using Torulopsis glabrata IFO 0005, and a novel biphasic culture method was developed on the basis of the metabolic flux analysis. T. glabrata requires the four vitamins nicotinic acid (NA), thiamine hydrochloride (B(1)), pyridoxine hydrochloride, and biotin for cell growth. The deficiency of these vitamins plays an essential role in pyruvate fermentation. In the present study, we considered the effects of the first two vitamins on the pyruvate fermentation. On the basis of several batch and fed-batch experiments, it was found that, as a result of glucose inhibition of cell growth, the initial glucose concentration should be around 30-40 g/L, and the glucose concentration during fermentation should be controlled at high level around 30 g/L. On the basis of an analysis of carbon flux distribution, a biphasic fermentation method was developed where the cultivation started with a high DO (at 40-50% of air saturation) for efficient cell growth and then was reduced to 5-10% for efficient pyruvate production. Since a fair amount of ethanol was formed when the DO concentration was decreased, the addition of NA turned out to be effective in reducing the ethanol formation. This may be due to a relaxing of the requirement for NADH oxidation by the alcohol dehydrogenase pathway. Since B(1) affects both the pyruvate dehydrogenase complex and pyruvate decarboxylase, its initial concentration must be carefully determined by considering both the cell growth and pyruvate production phases.

Candida↗
PubMed1992

Evidence that the acidic polysaccharide secreted by Agrobacterium radiobacter (ATCC 53271) has a seventeen glycosyl-residue repeating unit.

The extracellular anionic polysaccharide produced by the bacterium Agrobacterium radiobacter (ATCC 53271) contains D-galactose, D-glucose, and pyruvic acid in the molar ratio 2:15:2. Analysis of the methylated polysaccharide indicated the presence of terminal, non-reducing glucosyl, 3-, 4-, 6-, 2,4-, and 4,6-linked glucosyl residues, 3-linked 4,6-O-[(S)-1-carboxyethylidene]glucosyl residues, and 3-linked galactosyl residues. Partial acid hydrolysis of the methylated polysaccharide, followed by reduction with NaB2H4 and then O-ethylation, gave a mixture of alkylated oligoglycosyl alditols that were separated by reversed-phase h.p.l.c. and analyzed by 1H-n.m.r. spectroscopy, g.l.c.-m.s., and glycosyl-linkage composition analysis. Smith degradation of the polysaccharide gave three diglycosyl alditols that were separated by semi-preparative, high-pH anion-exchange chromatography, and were analyzed by 1H-n.m.r. spectroscopy, g.l.c.-m.s., and glycosyl-linkage composition analysis. The polymer obtained by NaBH4 reduction of the periodate-oxidized polysaccharide was methylated, and the noncyclic acetals were hydrolyzed with aq. 90% formic acid to generate a mixture of partially O-methylated mono- and di-glycosyl alditols. The partially O-methylated oligoglycosyl alditols were O-ethylated. The resulting alkylated oligoglycosyl alditols were separated by reverse-phase h.p.l.c. and then characterized by 1H-n.m.r. spectroscopy, g.l.c.-m.s., and glycosyl-linkage composition analysis. The results from the studies described here provide strong evidence that the acidic polysaccharide secreted by A. radiobacter (ATCC 53271) has a heptadecasaccharide repeating unit.

Carbohydrate Sequence↗
PubMedDate not supplied

[Effect of phytoecdysteroids and nerobol on parameters of carbohydrate and lipid metabolism and phospholipid spectrum of liver mitochondrial membrane in experimental diabetes mellitus of rats].

Phytoecdysteroids: ecdysterone and turkesterone, introduced orally to male rats with the body mass 180-120 g in a dose of 5 mg/l kg of mass and nerobol in a dose of 10 mg per 1 kg of the mass for 15 days against a background of the developed alloxan diabetes cause a considerable decrease in the content of free fatty acids of the blood serum, sharply increased after the subcutaneous injection of alloxan to the animals (150 mg per 1 kg of the mass). The content of glycogen, malonic dialdehyde, pyruvic acid and calcium transporting function of the liver mitochondria are also normalized. These changes are closely interrelated (and may be mutually conditioned) with the preparation-induced reduction of phospholipid spectrum of the liver mitochondrial membranes pathologically changed owing to insulin insufficiency. In this case phytoecdysteroids in the first turn normalize the fractions of phospholipids which play the structural role in the mitochondrial membranes, and nerobol normalizes the level of minor and monoacylic phospholipids.

Animals↗
PubMed2005

Development of an HPLC-fluorescence determination method for carboxylic acids related to the tricarboxylic acid cycle as a metabolome tool.

We report the simultaneous determination of the carboxylic acids related to the tricarboxylic acid (TCA) cycle, which plays an important role in producing adenosine triphosphate (ATP) and generating energy in mitochondria. Seven carboxylic acids from the TCA cycle, and pyruvic acid and 2-methylsuccinic acid, as an internal standard, were derivatized with a fluorescent reagent for carboxyl groups, 4-N,N-dimethylaminosulfonyl-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ), in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 4-N,N-dimethyaminopyridine as the coupling reagents, at 60 degrees C for 120 min. Subsequently, the excess DBD-PZ was removed efficiently using a cation-exchange cartridge, SDB-RPS (Empore). These fluorescent derivatives were separated well from each other on an octadecyl silica column (TSKgel ODS-80Ts, 250 x 4.6 mm, i.d.) with an eluent of acetonitrile-water containing 1% formic acid at a flow rate of 0.8 mL/min, and were detected fluorometrically at 560 nm, with excitation at 450 nm. The validation data were satisfactory in the range of 2.5-100 microm citric acid, isocitric acid, 2-oxoglutaric acid, succinic acid and fumaric acid. The detection limit (S/N = 3) for citric acid was 2 fmol on the column. The structures of these derivatives were confirmed by high-performance liquid chromatography-mass spectrometry, which proved that their carboxylic groups were completely labeled with DBD-PZ, except for oxaloacetic acid. This HPLC method was successfully applied to the analysis of TCA cycle metabolites in rat urine. The method will also be useful for metabolome research, such as for target analyses of metabolites with carboxyl groups, not only in urine but also in cells and organs.

Animals↗
PubMed1975

Fragmentation analysis of extracellular acid polysaccharides from seven Rhizobium strains. Part I. D-glucuronic acid-containing oligosaccharides.

The extracellular, bacterial polysaccharides from seven Rhizobium strains have been submitted to partial hydrolysis with acid. Several neutral oligosaccharides, some containing pyruvic acid, were isolated together with D-glucuronic acid-containing oligosaccharides. The polysaccharide from Rh. meliloti did not contain glucuronic acid. For the other six strains, the following components were characterized: 4-O-(beta-D-glucopyranosyluronic acid)-D-glucuronic acid, 4-O-(beta-D-glucopyranosyluronic acid)-D-glucose, and O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-D-glucose. These results indicate the presence of chains containing two beta-(1leads to4)-linked D-glucuronic acid residues, beta-linked to D-glucose at position 4.

Glucose↗
PubMed1980

Selective high-performance liquid chromatographic assays for hydralazine and its metabolites in plasma of man.

Selective high-performance liquid chromatographic assays for hydralazine (I), hydralazine pyruvic acid hydrazone (II) and the acetylation metabolites, namely s-triazolo[3,4-alpha]-phthalazine (V) and 3-hydroxymethyl (VI) and 3-methyl-s-triazolo[3,4-alpha]phthalazine (VII) in human plasma were developed. Utilizing the fluorescence of these compounds or their derivatives the limits of detection could be extended down to 5 nmole/l (1 ng/ml) for I, 1 nmole/l (0.2 ng/ml) for II and 0.5 nmole/l (0.1 ng/ml) for V--VII. The intra-assay coefficients of variation for the assays ranged from 2 to 7% over the concentration range 5.0 to 0.05 micromole/l and the inter-assay variability in the slope of the standard curves ranged rom 4 to 8%. An improved method for measuring the sum of I plus all its hydrazones (apparent I) was also developed. On addition of I to fresh plasma at 37 degrees, half the added I was converted to II within 15 min and there was no detectable level of I, 2 h after the addition. The plasma level--time course of I, and its metabolites in a healthy volunteer (slow acetylator) following separate oral and intravenous administrations of I indicated that I contributed only a small fraction (4.3 and 4.7% respectively) to the area under the plasma level--time curve of apparent hydralazine.

Chromatography, High Pressure Liquid↗
PubMed1979

Growth yields and fermentation balance of Bacteroides fragilis cultured in glucose-enriched medium.

Bacteroides fragilis is an obligate anaerobic bacterium classified with the gram-negative, non-sporeforming bacilli and is the Bacteroides species most frequently isolated from human infections. In the present study, experiments were designed to investigate growth characteristics of B. fragilis in a complex medium. In a minimal defined medium, which was employed for comparison purposes, B. fragilis grew with a generation time of 2 h. Growth of the organism in glucose-enriched medium used in the present study was superior. Maximum generation time was 60 min. Total and viable cells (colony-forming units) were 8.9 x 10(9) and 2.1 x 10(9), respectively, at maximum measurable growth. The molar growth yield (Ym) was 51.5. Growth yields were found to reach a maximum 2 to 3 h before maximum growth and to vary with respect to the phase of growth. Estimates of the fermentation products indicated that glucose was the sole energy substrate. Major products included acetic acid, propionic acid, lactic acid, and succinic acid. Other products included ethyl alcohol, pyruvic acid, and fumaric acid. No attempt was made to recover CO2 or formic acid. The OR balances from two experiments were 0.013 and -0.093 and the respective carbon recoveries were 6.268 and 6.241. The results of the present study show that B. fragilis is capable of rapid rates of growth in vitro by using glucose as the sole energy source.

Bacteroides fragilis↗
PubMed1968

Cystathionine metabolism in methionine auxotrophic and wild-type strains of Saccharomyces cerevisiae.

The role of cystathionine in methionine biosynthesis in wild-type and auxotrophic strains of Saccharomyces cerevisiae was studied. Homocysteine and cysteinerequiring mutants were selected for detailed study. Exogenously supplied cystathionine, although actively transported by all strains tested, could not satisfy the organic sulfur requirements of the mutants. Cell-free extracts of the wild-type, homocysteine, and cysteine auxotrophs were shown to cleave cystathionine. Pyruvic acid and homocysteine were identified as teh products of this cleavage. A mutant containing an enzyme which could cleave cystathionine to homocysteine in cell-free experiments was unable to use cystathionine as a methionine precursor in the intact organisms. The significance of this finding is discussed.

Amino Acids↗
PubMed2006

Metabolism of 4-amino-3-hydroxybenzoic acid by Bordetella sp. strain 10d: A different modified meta-cleavage pathway for 2-aminophenols.

Bordetella sp. strain 10d metabolizes 4-amino-3-hydroxybenzoic acid via 2-hydroxymuconic 6-semialdehyde. Cell extracts from 4-amino-3-hydroxybenzoate-grown cells showed high NAD(+)-dependent 2-hydroxymuconic 6-semialdehyde dehydrogenase, 4-oxalocrotonate tautomerase, 4-oxalocrotonate decarboxylase, and 2-oxopent-4-enoate hydratase activities, but no 2-hydroxymuconic 6-semialdehyde hydrolase activity. These enzymes involved in 4-amino-3-hydroxybenzoate metabolism were purified and characterized. When 2-hydroxymuconic 6-semialdehyde was used as substrate in a reaction mixture containing NAD(+) and cell extracts from 4-amino-3-hydroxybenzoate-grown cells, 4-oxalocrotonic acid, 2-oxopent-4-enoic acid, and 4-hydroxy-2-oxovaleric acid were identified as intermediates, and pyruvic acid was identified as the final product. A complete pathway for the metabolism of 4-amino-3-hydroxybenzoic acid in strain 10d is proposed. Strain 10d metabolized 2-hydroxymuconic 6-semialdehyde derived from 4-amino-3-hydroxybenzoic acid via a dehydrogenative route, not via a hydrolytic route. This proposed metabolic pathway differs considerably from the modified meta-cleavage pathway of 2-aminophenol and those previously reported for methyl- and chloro-derivatives.

4-Aminobenzoic Acid↗
PubMed1978

Metabolism of 3, 4-dihydroxyphenylalanine, its metabolites and analogues in vivo in the rat: urinary excretion pattern.

The metabolism and interrelationships of orally and intraperitoneally administered L-dopa, related amino acids and their metabolites have been studied 2. Amino acids were decarboxylated. N-Methyldopa formed dopamine but not epinine. D-Dopa was absorbed from the intestine and metabolized by a series of reactions which resulted in greater decarboxylation than was observed after L-dopa. Transamination was a minor pathway. 3. m-Hydroxylated phenylpyruvic acids were poorly reduced, but vanilpyruvic acid was reduced fairly readily. Lactic acids were largely unchanged. Lactic and pyruvic acids formed phenylethylamines and their metabolites. Small amounts of phenylpyruvic acids may be decarboxylated to phenylacetic acids. 4. Glycine conjugates were formed from phenylacetic acids, a partially reversible change 3,4-Dihydroxyphenylacetic acid was metabolized to homovanillic and m-hydroxyphenylacetic acids, especially when given orally. Little 3-hydroxy-4-methoxyphenylacetic acid was oxidized to 3,4-dihydroxyphenylacetic acid but some increase in m-hydroxyphenylacetic acid excretion was observed. 5. 2-Phenylethanol analogues were largely converted to the corresponding acids. 3,4-Dihydroxyphenylethanol was partially m-O-methylated before oxidation. 6. beta-Phenylethylamine analogues were oxidized mainly to phenylacetic acids. but a variable amount of analogous phenylethanol was also formed, especially from m-tyramine. Dopamine was O-methylated, a process not readily reversible. It was also p-dehydroxylated following oral and intraperitoneal administration but not after oral neomycin; biliary excretion of amines may be involved in this sequence of events. N-Methylated amines were oxidized less readily than the parent amine. 7. Differences in route of administration resulted in quantitative changes in degradation pathways, an effect deriving, to some extent, from p-dehydroxylation and O-methylation in the gut.

Alcohols↗
PubMedDate not supplied

[Phytin efficacy in correction of the impaired detoxication liver function in the long-term compression syndrome in rats in prepubertal period].

The compression syndrome was reproduced in rats aged one month and the efficacy of phytin in correcting the activity infringement and restoring the content of basic components of the hepatocyte monooxygenase enzyme system was studied in the postcompression period. The compression led to pronounced inhibition of the activity of aniline hydroxylase and amidopyrine M-demethylase, reduced the content of liver microsomal protein and cytochromes P-450 and b5, and increased the level of medium- molecular-weight (MMW) peptides in the blood serum. A six-day treatment with phytin restored the normal level of the liver monooxygenase system components and MMW peptides. Phytin reduced the level of lactic acid (LA) and increased that of pyruvic acid (PA) in liver tissues, which led to a sharp drop in the LA/MA ratio indicative of a decrease in the extent of hypoxia.

Aging↗
PubMedDate not supplied

Influence of high hydrostatic pressure on the formation of keto and amino acids by a barotolerant strain of Pseudomonas aeruginosa.

The peculiarities of the growth and extracellular accumulation of free keto and amino cids by a barotolerant culture (strain 0798) in culturing on Ran's glucose-mineral medium conditions of 1, 200, 300, and 500 atm were investigated. At a high pressure the culture possesses the ability for extracellular accumulation of free keto and amino acids, pyruvic, alpha-ketoglutaric, and oxaloacetic acids, alanine, and glutamic acid, while under conditions of atmospheric pressure, chiefly valine is accumulated in the medium, and there are no extracellular keto acids. The established specificity of the extracellular accumulation of keto and amino acids under conditions of high hydrostatic and atmospheric pressure is due to the different sensititivy of the enzyme systems participating in the biosynthesis of free keto and amino acids to the influence of high hydrostatic pressure.

Amino Acids↗
PubMed2002

Pancreatic and extrapancreatic effects of GLP-1.

Glucagon-like peptide-1 (GLP-1), an incretin hormone which helps to regulate plasma glucose levels, is considered a potential agent for the treatment of type-2 diabetes mellitus, because of its insulinotropic capacity and insulinomimetic actions. In normal conditions, the beta-cell secretory response to GLP-1 is modulated by the extracellular concentration of D-glucose; however, the recognition of D-glucose by the beta-cell is often impaired in type-2 diabetes, and this could impede the full GLP-1 insulinotropic action. Non-glucidic substrates, such as the dimethyl ester of succinic acid, restore the effect of GLP-1 in the isolated perfused rat pancreas of normal or diabetic rats, in the absence of any other exogenous nutrient; likewise, the dimethyl ester of succinic or L-glutamic acid, and the monomethyl ester of pyruvic acid, potentiate the in vivo beta-cell secretory response to GLP-1 in normal and diabetic rats. Therefore, it was proposed that nutrients susceptible to bypass the site-specific defects of the diabetic beta-cell, could be used to potentiate and/or prolong the insulinotropic action of antidiabetic agents such as GLP-1. In vitro, GLP-1 insulin-like effects on glucose metabolism have been documented in normal and diabetic rat liver, and in rat and human skeletal muscle. In rat and human adipocytes, GLP-1 is lipolytic and/or lipogenic, and also stimulates parameters involved in the glucose metabolism. In liver, muscle and fat, GLP-1 seems to act through specific receptors, apparently different--at least in liver and muscle--in structure or signaling pathway from the pancreatic one. It is proposed that an inositolphosphoglycan might be a second messenger of GLP-1 action in extrapancreatic tissues.

Animals↗
PubMed1991

Regulation of collagen production in freshly isolated cell populations from normal and cirrhotic rat liver: effect of lactate.

Previous work has shown that lactic acid, and to a lesser extent pyruvic acid, is able to increase collagen synthesis significantly in liver slices of CCl4-treated rats but not normal rats. The purpose of this report is to document which cells in the cirrhotic liver are responsible for the lactate-stimulated increase in collagen synthesis. It was found that (a) incorporation of 3H-proline into protein-bound 3H-hydroxyproline is increased threefold to fourfold in hepatocytes from CCl4-treated rats as compared with normal rat hepatocytes; (b) neither the hepatocytes from normal nor those from CCl4-treated rats modify their collagen synthesizing capacity when 30 mmol/L lactic acid was added to the incubation medium; (c) nonparenchymal cells obtained from livers of CCl4-treated rats synthesize much less collagen than hepatocytes, but their synthesis is stimulated twofold by lactic acid; (d) from the different nonparenchymal cells, only fat-storing (Ito) cells increase collagen synthesis when lactic acid is present in the incubation medium. These results suggest that the increased lactic acid levels observed in patients with alcoholic hepatic cirrhosis may play an important role in the development of fibrosis by stimulating collagen production by fat-storing (Ito) cells.

Animals↗
PubMedDate not supplied

The metabolism of alpha-aminobenzo(b)thiophene-3-propionic acid (the sulfur analog of tryptophan) in the rat.

The biotransformation of 3H-labeled alpha-aminobenzo[b]thiophene-3-propionic acid (the sulfur analog of tryptophan) was investigated in rats. Forty-eight hours after ip administration, 80% of the radioactive dose was recovered in the urine and 5% in the feces; tissue levels of radioactivity accounted for the remainder of the administered dose. The urinary metabolites were identified by a combination of thin-layer chromatography, gas chromatography, and gas chromatography-mass spectrometry, and were quantitated by thin-layer chromatography and liquid-scintillation counting to give, as percentages of the administered dose, unchanged alpha-aminobenzo[b]thiophene-3-propionic acid (20.6%), benzo[b]thiophene-3-acetic acid (1.3%), benzo[b]thiophene-3-pyruvic acid (14.2%), benzo[b]thiophene-3-lactic acid (4.9%), and N-(benzo[b]thiophene-3-acetyl)glycine (46.2%).

Animals↗
PubMedDate not supplied

[Hypoinsulinemia and bioenergetic processes in the rat cerebral cortex].

Increase in activity of lactate dehydrogenase, of its isoenzymes LDH1, LDH2 and LDH3 as well as in content of lactic acid with simultaneous decrease in the pyruvic acid content were found in brain hemispheres of rats with alloxan diabetes. A decrease in the rate of energy reactions in rat brain hemispheres, caused by impairment of glucose oxidation in the Krebs cycle, proved to be the specific property of metabolic alterations in these cells under conditions of hypoinsulinemia.

Adenine Nucleotides↗