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PubMed1981

[Histo- and biochemical characteristics of rat skeletal muscle after prolonged static loading].

For 100 days the rats were kept in vertical position, and after histo- and biochemical characteristics of the musc. gastrocnemius (fast) and musc. soleus (slow) were studied. A prolonged static loading was stated to produce increasing number of white and intermediate fibres in the m. gastrocnemius and intermediate fibres in the m. soleus. The fast and slow muscles reacted differently to the static loading; this was evident from a decreased content of glycogen in muscle fibers. A statistically important decrease in lactate dehydrogenase (LDH) activity in blood serum and the m. gastrocnemius was found, while in the m. soleus its level remained unchanged. It was found for certain that lactic acid content increased in the muscles studied, and its content did not change in blood serum. As to pyruvic acid content, it increased in blood serum, decreased in the m, gastrocnemius and did not differ from the control in the m. soleus. In the m. gastrocnemius an increased activity of slowly migrating LDH isoenzymes was noted, while in the m. soleus--that of fast migrating ones. At a prolonged static loading there was normalization in histo- and biochemical characteristics as it is at the dynamic loading.

Animals↗
PubMed1985

Heat-shock treatment lethal for mammalian cells deprived of glucose and glutamine: protection by alpha-keto acids.

Nil and Nilpy hamster cells exposed to temperatures of 44 degrees C to induce the heat-shock proteins survive such exposure for 2 h or more when incubated in Eagle's Minimum Essential Medium with 10% undialyzed fetal calf serum. If D-glucose and L-glutamine are withdrawn from the medium during heat treatment, nearly all the cells are killed by as little as 20 min at 44 degrees C. Several alpha-keto acids, pyruvate, alpha-ketobutyrate, oxaloacetate, and alpha-ketoglutarate, protect cells from the lethal action of the heat treatment in the absence of D-glucose and L-glutamine. L-Glucose and D-glutamine are without effect. Efforts to reverse lethal effects have not been successful.

Animals↗
PubMed2003

Post-ischemic treatment with dipyruvyl-acetyl-glycerol decreases myocardial infarct size in the pig.

The beneficial effects of pyruvate in organ reperfusion injury have been documented, however the therapeutic use of pyruvate has been hindered by the lack of an appropriate delivery method. Pyruvic acid is unstable and high rates of sodium pyruvate infusion are toxic. Dipyruvyl-acetyl-glycerol (DPAG) ester was developed as a novel method for intravenous pyruvate delivery at a high rate without sodium overload. We tested the ability of DPAG to reduce myocardial infarct size when administered after severe myocardial ischemia in an anesthetized open-chest pig model of ischemia-reperfusion injury. Ischemia was induced by total occlusion of the distal 2/3 of the left anterior descending coronary artery for one hour, followed by two hours of reperfusion. Animals were either untreated (n = 7), or treated with intravenous DPAG (8.0 mg/kg(-1). min(-1), n = 8) during the two hours of reperfusion. Infarct size was measured on blinded samples using tetrazolium staining. The DPAG treated group had elevated pyruvate levels (0.82 +/- 0.07 mM) and reduced infarct size (20.1 +/- 4.2% of the volume at risk, compared to 30.8 +/- 4.6% in the untreated animals (p < 0.05)), with no difference in blood pressure or heart rate between groups. In conclusion, an intravenous infusion of DPAG safely increases arterial pyruvate concentration and reduces myocardial infarct size following myocardial ischemia.

Animals↗
PubMed2003

Rational design, synthesis, and structure-activity relationships of novel factor Xa inhibitors: (2-substituted-4-amidinophenyl)pyruvic and -propionic acids.

An inhibitor of factor Xa (fXa), the m-substituted benzamidine AXC1578 (1a), was structurally modified with the aim of increasing its potency. In particular, pyruvic acid and propionic acid substituents were incorporated into the P1 benzamidine moiety to introduce a favorable interaction with the oxy-anion hole in the catalytic triad region of fXa. This strategy was based on computational docking studies using the extracted active site of fXa. The validity of the computational model was supported by the acquisition of X-ray crystal structures of the 1a-trypsin and 3b-trypsin complexes (the homology around the active sites of fXa and trypsin is high). The above modifications significantly increased the inhibitory activity toward fXa, whereas the high selectivity for fXa versus thrombin was maintained or enhanced. Compounds 3b, 3c, 3e, and 4b are considered to be potential lead compounds for the development of orally active anticoagulant drugs because they demonstrated potent activity when administered orally to cynomolgus monkeys.

Administration, Oral↗
PubMed1986

Identification of pyruvated monosaccharides in polysaccharides by gas-liquid chromatography mass spectrometry.

Twelve bacterial polysaccharides of known structure containing a representative range of pyruvated monosaccharides, were methanolysed, trimethylsilylated, and analysed by g.l.c. and g.l.c.-m.s. Except for 3,4-O-(1-carboxyethylidene)-L-rhamnose, which was unusually labile, the pyruvic acid substituents were largely retained during methanolysis and the Me3Si derivatives of the resulting pyruvated methyl glycosides gave distinctive g.l.c. peaks with characteristic mass spectra. The pyranose rings of 4,6-O-(1-carboxyethylidene)-D-glucose, 4,6-O-(1-carboxyethylidene)-D-mannose, 4,6-O-(1-carboxyethylidene)-D-galactose, and 3,4-O-(1-carboxyethylidene)-D-galactose survived the methanolysis, but that of 2,3-O-(1-carboxyethylidene)-D-glucuronic acid was cleaved to give the methyl ester of 2,3-O-(1-carboxyethylidene)-aldehydo-D-glucuronic acid dimethyl acetal. In the case of 2,3-O-(1-carboxyethylidene)-D-galactose, cleavage of the pyranose ring was less complete; under the conditions used in these experiments two-thirds of the pyranose rings were intact while one-third were cleaved to give the methyl ester of 2,3-O-(1-carboxyethylidene)-aldehydo-D-galactose dimethyl acetal. A very small amount of 3,4-O-(1-carboxyethylidene)-L-rhamnose from one polysaccharide retained its pyruvic acid substituent after gentle methanolysis to give the methyl ester of 3,4-O-(1-carboxyethylidene)-aldehydo-L-rhamnose dimethyl acetal. Susceptibility to cleavage of the pyranose ring during methanolysis appears to be a property of pyruvated monosaccharides with trans-fused 1,3-dioxolane rings.

Chromatography, Gas↗
PubMed1998

Regulation of thiamin diphosphate-dependent 2-oxo acid decarboxylases by substrate and thiamin diphosphate.Mg(II) - evidence for tertiary and quaternary interactions.

The regulatory mechanism of substrate activation in yeast pyruvate decarboxylase is triggered by the interaction of pyruvic acid with C221 located on the beta domain at >20 A from the thiamin diphosphate (ThDP). To trace the putative information transfer pathway, substitutions were made at H92 on the alpha domain, across the domain divide from C221, at E91, next to H92 and hydrogen bonded to W412, the latter being intimately involved in the coenzyme binding locus. Additional substitutions were made at D28, E51, H114, H115, I415 and E477, all near the active center. The pH-dependent steady-state kinetic parameters, including the Hill coefficient, provide useful insight to this effort. In addition to C221, the residues H92, E91, E51 and H114 and H115 together appear to have a critical impact on the Hill coefficient, providing a pathway for information transfer. To study the activation by ThDP.Mg(II), variants at G231 (of the conserved GDG triplet) and at N258 and C259 (all three being part of the putative ThDP fold) of the E1 component of the Escherichia coli pyruvate dehydrogenase multienzyme complex were studied. Kinetic and spectroscopic evidence suggests that the Mg(II) ligands are very important to activation of the enzymes by cofactors.

Binding Sites↗
PubMed1996

Organic acid excretion by Streptomyces lividans TK24 during growth on defined carbon and nitrogen sources.

Cultures of Streptomyces lividans TK24 grown in defined media containing certain rapidly used carbon and nitrogen sources excreted high levels of organic acids. These were identified by HPLC and enzymic assays as pyruvic acid and 2-oxoglutaric acid. Acidification occurred only with glucose as the principal carbon source, and depended on the nitrogen source used. With nitrate as the sole nitrogen source, high levels of pyruvate and small amounts of 2-oxoglutarate were produced. Carbon from D[U-14C]glucose was converted into both organic acids. Combining glucose with a selection of amino acids as primary nitrogen/secondary carbon sources yielded less pyruvate and more 2-oxoglutarate. Carbon from both 14C-labelled glucose and amino acids was metabolized to both organic acids. Adding nitrate to this combination caused a reversion of the acid production pattern to that of the glucose-nitrate combination, as if the amino acids were absent. Addition of ammonium salts to any combination of carbon and nitrogen sources completely prevented organic acid formation.

Biotechnology↗
PubMedDate not supplied

[The effect of guanosyl-5'-monophosphate on metabolic processes in rats with experimental myocarditis].

Ten days course of 5'-GMP intramuscular administration at a dose of 25 mg/kg into rats with adrenaline-produced myocarditis led to normalization of NAD content in myocardial tissue which contributed to restoration of NAD-dependent isocitrate dehydrogenase activity. During the 5'-GMP administration content of ATP and creatine phosphate was kept at the same low level as compared with controls, while restoration of glycogen content was retarded in the heart muscle. Activity of lactate dehydrogenase and lactic acid content were not altered. The decrease in content of pyruvic acid detected in response to 5'-GMP administration may occur due to elevated decarboxylation of pyruvate as a result of NAD content increase in heart muscle.

Animals↗
PubMed1996

An HPLC method for the quantitative determination of hexeneuronic acid groups in chemical pulps.

It has recently been demonstrated that 4-deoxy-L-threo-hex-4-enopyranosyluronic acid ("hexeneuronic acid") is present in kraft pulps and linked to the xylan backbone. An analytical method for the quantitative determination of hexeneuronic acid groups has now been developed. The procedure involves a selective hydrolysis with mercuric acetate of the glucosidic linkage between the hexeneuronic acid group and the xylan chain, followed by oxidation with periodate to form beta-formyl pyruvic acid. The latter is reacted with thiobarbituric acid, and the red-coloured adduct formed is separated by reverse phase HPLC and quantified by measuring the absorbance at 549 nm. Some kraft pulps have been analysed to illustrate the contribution of hexeneuronic acid groups to the total amount of oxidizable structures present in such pulps.

Chromatography, High Pressure Liquid↗
PubMed1998

Effect of glucagon on the plasma concentration of uridine.

To determine whether glucagon affects the plasma concentration of uridine, we administered 100 mL physiological saline containing 1 mg glucagon or 100 mL physiological saline alone intravenously over 1 hour to healthy subjects. Glucagon decreased the plasma concentration of uridine from 5.72 +/- 1.05 to 4.80 +/- 0.60 micromol/L but increased the concentrations of cyclic adenosine monophosphate (cAMP) in plasma and pyruvic acid and lactic acid in blood 59-, 1.4-, and 1.3-fold, respectively. Although glucagon increased urinary excretion of uric acid, it did not affect the plasma concentration of purine bases (hypoxanthine, xanthine, and uric acid) or urinary excretion of oxypurines and uridine, indicating that glucagon does not affect purine degradation and suggesting that glucagon does not affect adenosine triphosphate (ATP) consumption-induced pyrimidine degradation. In contrast, physiological saline did not affect any of the measured variables. These results suggest that glucagon enhanced Na+-dependent uridine uptake from the blood into the cells, since glucagon stimulates Na+-dependent uridine uptake into cells in vitro.

Adult↗
PubMed1998

Xylitol-induced increase in the plasma concentration and urinary excretion of uridine and purine bases.

To determine whether xylitol increases the plasma concentration and urinary excretion of uridine together with purine bases, we administered xylitol (0.6 g/kg weight) intravenously to six normal subjects using a 10% xylitol solution. Xylitol infusion increased the plasma concentration and urinary excretion of uridine, as well as purine bases, while it decreased both the concentrations of inorganic phosphate in plasma and pyruvic acid in blood and increased the blood concentration of lactic acid. These results suggest that an increase in the plasma concentration and urinary excretion of uridine is ascribable to increased pyrimidine degradation following purine degradation induced by xylitol.

Adult↗
PubMedDate not supplied

On the effect of aliphatic saturated dicarboxylic acids on anaerobic glycolysis in chicken embryo.

Oxalic, succinic, glutaric and pimelic acid (5 mM) had no effect on lactate formation from glucose if added to a crude extract of chicken embryo at the same time as substrate and cofactors; conversely malonic, adipic, suberic, azelaic and sebacic acid had an inhibitory effect ranging from 20% to 35%. When the enzyme preparation was pre-incubated with the dicarboxylic acids for one hour before beginning the experiments, all compounds tested, with the exception of succinate, inhibited anaerobic glycolysis. Hexokinase activity was significantly reduced by saturated dicarboxylic acids from C3 to C10, but not by oxalic acid. Phosphofructokinase was inhibited only by oxalic, pimelic and suberic acid. Pyruvate kinase appeared sensitive only to oxalic acid (64% inhibition).

Anaerobiosis↗
PubMed2005

Prospective protective role of melatonin against arsenic-induced metabolic toxicity in Wistar rats.

Subchronic exposure to arsenic is associated with alteration of glucose homeostasis. Arsenic treatment (as sodium arsenite) of male Wistar rats (weighing 130-150 g) at a dose of 5.55 mg kg(-1) body weight (equivalent to 35% of LD(50)) (i.p.) per day for a period of 30 days produced hypoglycemia, with associated increased urinary excretion of glucose and depletion of liver glycogen and pyruvic acid contents. Mobilization of free amino acids from kidney to liver was facilitated by arsenic treatment. Arsenic exposure significantly decreased the glutamate-pyruvate transaminase activity in kidney. Glucose 6-phosphatase activity in liver tissue was also significantly decreased after arsenic treatment. In addition to these, liver lactate dehydrogenase activity was elevated due to arsenic treatment. Melatonin supplementation (i.p.) at a dose of 10 mg kg(-1) day(-1) for last five days prior to sacrifice reversed most of the above changes caused by arsenic. Melatonin, being a potent free radical scavenger may reduce arsenic-induced free radical production, and thereby, eliminating its toxic effects. So, arsenic-induced hypoglycemia, with associated glycogenolytic as well as glycolytic activities of liver can be partially counteracted by melatonin supplementation. Accordingly, it may be suggested that melatonin can serve as a prospective protective agent against arsenic-induced metabolic toxicity.

Alanine Transaminase↗
PubMed1992

VLDL apolipoprotein B-100, a potential indicator of the isotopic labeling of the hepatic protein synthetic precursor pool in humans: studies with multiple stable isotopically labeled amino acids.

Four adult men received a 48-h constant intravenous infusion of [2H4]lysine, [2H3]leucine, L-[ring-13C6]phenylalanine, and L-[1,2,3,-13C3]alanine. Subjects ingested hourly meals for two 12-h periods, separated to two 12-h fasting periods. The isotopic enrichments of free amino acids in venous plasma and in VLDL apolipoprotein B-100 (apoB)-bound amino acids, plasma alpha-keto isocaproic acid (alpha-KIC) and plasma pyruvic acid (PYR) were measured by negative chemical ionization gas chromatography-mass spectrometry. By 7 h of infusion, all four amino acids achieved an equilibrium isotopic enrichment (EIE) in plasma and in apoB. In the fed state, the EIE of the amino acids in apoB was lower than that in plasma free amino acids. The ratio EIE-apoB:EIE-plasma differed significantly among amino acids in the fed state (alanine 0.30; lysine 0.64; leucine 0.70; phenylalanine 0.81). In the postabsorptive state, the EIE-apoB:EIE-plasma ratio rose significantly compared with the fed state (alanine 0.38; lysine 0.73; leucine 0.94; phenylalanine 1.05). Plasma PYR and apoB-alanine were in isotopic equilibrium irrespective of nutritional state. The EIE-apoB-leucine:EIE-plasma-alpha-KIC ratio rose from 0.75 in the fed state to near 1 in the postabsorptive state. We conclude that the contribution of systemic amino acids to apoB-100 synthesis is sensitive to nutritional state, and that systemic essential amino acids seem to be preferentially incorporated into apoB.

Adult↗
PubMed1989

Oxidative properties of carp red and white muscle.

Substrate preferences of isolated mitochondria and maximal enzyme activities were used to assess the oxidative capacities of red muscle (RM) and white muscle (WM) of carp (Cyprinus carpio). A 14-fold higher activity of citrate synthase (CS) in RM reflects the higher mitochondrial density in this tissue. RM mitochondria oxidize pyruvate and fatty acyl carnitines (8:O, 12:O, 16:O) at similarly high rates. WM mitochondria oxidize these fatty acyl carnitines at 35-70% the rate of pyruvate, depending on chain length. WM has only half the carnitine palmitoyl transferase/CS ratio of RM, but similar ratios of beta-hydroxyacyl CoA dehydrogenase/CS. Ketone bodies are poor substrates for mitochondria from both tissues. In both tissues mitochondrial alpha-glycerophosphate oxidation was minimal, and alpha-glycerophosphate dehydrogenase was present at low activities, suggesting the alpha-glycerophosphate shuttle is of minor significance in maintaining cytosolic redox balance in either tissue. The mitochondrial oxidation rates of other substrates relative to pyruvate are as follows: alpha-ketoglutarate 90% (RM and WM); glutamate 45% (WM) and 70% (RM); proline 20% (WM) and 45% (RM). Oxidation of neutral amino acids (serine, glycine, alanine, beta-alanine) was not consistently detectable. These data suggest that RM and WM differ in mitochondrial properties as well as mitochondrial abundance. Whereas RM mitochondria appear to be able to utilize a wide range of metabolic fuels (fatty acids, pyruvate, amino acids but not ketone bodies), WM mitochondria appear to be specialized to use pyruvate.

Animals↗
PubMed2004

High-performance liquid chromatographic assay of lactic, pyruvic and acetic acids and lactic acid stereoisomers in calf feces, rumen fluid and urine.

To facilitate clinical investigation of metabolic acidosis, a high-performance liquid chromatographic method was adapted and validated for the chiral separation of D-(-) and L-(+)-lactic acid in calf feces, rumen fluid and urine. A non-chiral method was also adapted and validated for the separation of pyruvic, acetic and DL-(+/-)-lactic acids in calf feces and DL-(+/-)-lactic and pyruvic acids in rumen fluid. Separation and quantification were achieved using a reversed phase sulphonated polystyrenedivinylbenzene analytical column for pyruvic, acetic and racemic lactic acids and by a 3 microm octadecylsilane (ODS) packed analytical column coated with N,N-dioctyl-L-alanine as the chiral selector for the separation of lactic acid enantiomers with Cu(II)-containing eluents by stereoselective ligand exchange chromatography. Endogenous analytes were present in validation samples over a range of concentrations (0.2-14.8 mmol/l). For the stereoselective assay, mean intra-day accuracy ranged from 90.6 to 108.4% and intra-day precision from 0.3 to 13.8%. For the non-stereoselective assay, mean intra-day accuracy ranged from 90.4 to 108.8% and intra-day precision from 1.5 to 11.1%. The limit of quantitation was 1.0 mmol/l for D- and L-lactic acid, 0.06125 mmol/l for pyruvic acid, 1.0 mmol/l for DL-lactic acid and 1 mmol/l for acetic acid. These assays can be used to study the role of the gastrointestinal tract and kidney in metabolic acidosis.

Acetic Acid↗
PubMedDate not supplied

Protective effect of alpha-keto acids on the oxidative hemolysis.

We studied antioxidative properties of various concentrations (0.3-2 mM) of biochemically important alpha-keto acids: pyruvate, alpha-ketoglutarate, oxaloacetate, glyoxylic acid as aldehyde acid and also 2-methyl-thiazolidyne-2,4-dicarboxylic acid and their effect on the oxidative hemolysis of human erythrocytes induced by hydrogen peroxide (H2O2). Normal erythrocytes proved to be very resistant to oxidative damages, so the high concentration of H2O2 (10 mM) as well as the presence of natrium azide, a catalase inhibitor, was necessary. The levels of malonyldialdehyde (MDA), reactive oxygen species (ROS) and hemoglobin (Hb) released were evaluated as the measure of red cell peroxidative hemolysis. Pyruvate, at the lowest used concentration (0.3 mM), caused the inhibition of lipid peroxidation (MDA) and a drop in the level of ROS, as well as a diminution of the degree of hemolysis and the effects were stronger than those of other alpha-keto acids. At the highest (2 mM) concentration, the protective effect against oxidative damage of all the investigated alpha-keto acids was similar and amounted to nearly 50% in relation to the control sample. On the contrary, in the case of aldehyde acid, e.g. glyoxylic acid, no protective effect in the same range of concentrations was found. This confirms the participation of non-enzymatic oxidative decarboxylation of alpha-keto acids in the hydrogen peroxide decomposition process.

Adult↗
PubMedDate not supplied

[Metabolism in experimental chronic ischemic heart disease].

An increase in frequency of heart contractions, changes in the bioelectrical heart activity and decrease of the force-pump heart function are observed in the rabbits with model chronic ischemic heart disease lipid metabolism in significantly changed the concentration of cholesterol in the right ventricle myocardium as well as the concentrations of unsaturated lipid acids in the heart tissues increase, while the content of saturated lipid acids and antioxidant activity of plasma decrease. Bioenergetic processes change as follows: succinate-dehydrogenase and alpha-keto-glutarate-dehydrogenase activity decrease, while the concentrations of glycogen, lactic and pyruvic acids and lactate dehydrogenase activity in the heart tissues increase.

Animals↗