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PubMed2006

Haemodynamic and metabolic effects of resuscitation with Ringer's ethyl pyruvate in the acute phase of porcine endotoxaemic shock.

BACKGROUND: Ethyl pyruvate has been shown to possess anti-inflammatory and free radical scavenging properties. However, the haemodynamic effects of ethyl pyruvate have not been studied in detail. We investigated the systemic, regional and microcirculatory haemodynamic and metabolic effects of resuscitation with Ringer's ethyl pyruvate solution (REPS) vs. Ringer's acetate (RA) in an acute model of porcine endotoxaemic shock. METHODS: Fourteen anaesthetized pigs received an infusion of endotoxin that was increased stepwise over 30 min to a rate of 2.5 microg/kg/h. After 60 min of endotoxaemia, the animals were resuscitated with either ethyl pyruvate 40 mg/kg, given as REPS, or the equivalent volume of RA, administered over 10 min. Thereafter, an infusion of either ethyl pyruvate 40 mg/kg/h, given as REPS, or the equivalent volume of RA, was started, and the maintenance fluid was reduced so that the total amount of fluid given was kept constant. The experiment was terminated after 300 min of endotoxaemia. RESULTS: Endotoxin infusion led to a hypodynamic state that was reversed by fluid resuscitation after 60 min. Progressive deterioration ensued and, after 300 min, all animals were again hypodynamic. No differences in response to treatment were found between the groups with regard to systemic haemodynamics, renal artery or portal vein flow or microcirculatory flow in the liver, kidney, ileal serosa or mucosa. Metabolic acidosis and increased arterial blood lactate developed in both groups, but, in the REPS group, the base excess was significantly lower from 150 min and the anion gap was significantly higher at 150 and 210 min. CONCLUSION: We could not demonstrate any difference between REPS and RA for resuscitation in this model of acute porcine endotoxaemic shock.

Acute Disease↗
PubMed1987

Nucleotide sequence of the cDNA encoding the precursor for mitochondrial serine:pyruvate aminotransferase of rat liver.

The nucleotide sequence of the mRNA coding for the precursor of mitochondrial serine:pyruvate aminotransferase of rat liver was determined from those of cDNA clones. The mRNA comprises at least 1533 nucleotides, except the poly(A) tail, and encodes a polypeptide consisting of 414 amino acid residues with a molecular mass of 45,834 Da. Comparison of the N-terminal amino acid sequence of mitochondrial serine:pyruvate aminotransferase with the nucleotide sequence of the mRNA showed that the mature form of the mitochondrial enzyme consisted of 390 amino acid residues of 43,210 Da. The amino acid composition of mitochondrial serine:pyruvate aminotransferase deduced from the nucleotide sequence of the cDNA showed good agreement with the composition determined on acid hydrolysis of the purified protein. The extra 24 amino acid residues correspond to the N-terminal extension peptide (pre-sequence) that is indispensable for the specific import of the precursor protein into mitochondria. In the extension peptide there are four basic amino acids distributed among hydrophobic amino acids and, as revealed on helical wheel analysis, the putative alpha-helical structure of the peptide was amphiphilic in nature. The secondary structures of the mature serine:pyruvate aminotransferase and three other aminotransferases of rat liver were predicted from their amino acid sequences. Their secondary structures exhibited a common feature and so we propose the specific lysine residue which binds pyridoxal phosphate as the active site of serine:pyruvate aminotransferase.

Amino Acids↗
PubMed1986

Utilization of Lactate Isomers by Propionibacterium freudenreichii subsp. shermanii: Regulatory Role for Intracellular Pyruvate.

Five strains of Propionibacterium freudenreichii subsp. shermanii utilized the l-(+) isomer of lactate at a faster rate than they did the d-(-) isomer when grown with a mixture of lactate isomers under a variety of conditions. ATCC 9614, grown anaerobically in defined medium containing 160 mM dl-lactate, utilized only 4 and 15% of the d-(-)-lactate by the time 50 and 90%, respectively, of the l-(+)-lactate was used. The intracellular pyruvate concentration was high (>100 mM) in the initial stages of lactate utilization, when either dl-lactate or the l-(+) isomer was the starting substrate. The concentration of this intermediate dropped during dl-lactate fermentation such that when only d-(-)-lactate remained, the concentration was <20 mM. When only the d-(-) isomer was initially present, a similar relatively low concentration of intracellular pyruvate was present, even at the start of lactate utilization. The NAD-independent lactate dehydrogenase activities in extracts showed different kinetic properties with regard to pyruvate inhibition, depending upon the lactate isomer present. Pyruvate gave a competitive inhibitor pattern with l-(+)-lactate and a mixed-type inhibitor pattern with d-(-)-lactate. It is suggested that these properties of the lactate dehydrogenases and the intracellular pyruvate concentrations explain the preferential use of the l-(+) isomer.

Journal Article↗
PubMed1962

DEGRADATION OF PYRUVATE BY MICROCOCCUS LACTILYTICUS I. : General Properties of the Formate-Exchange Reaction.

McCormick, N. G. (University of Washington, Seattle), E. J. Ordal, and H. R. Whiteley. Degradation of pyruvate by Micrococcus lactilyticus. I. General properties of the formate-exchange reaction (J. Bacteriol. 83:887-898. 1962.-At an alkaline pH, extracts of Micrococcus lactilyticus(2) catalyze the phosphoroclastic degradation of pyruvate to formate and acetyl phosphate and the rapid exchange of formate into the carboxyl group of pyruvate. At an acid pH, hydrogen, carbon dioxide, and acetyl phosphate are produced, and carbon dioxide is exchanged into the carboxyl group of pyruvate. A concentration of approximately 1 m phosphate is required for the phosphoroclastic reaction and formate exchange; the production of carbon dioxide and hydrogen is greatly inhibited by high concentrations of phosphate. Formate exchange requires a divalent metal ion and is stimulated by reducing agents and an atmosphere of hydrogen. Inhibition by p-chloromercuribenzoate, Zn(++), Cd(++), and arsenite indicates that sulfhydryl groups on the enzyme are involved in the reaction; the inhibition by arsenite and Cd(++) may be relieved by 2,3-dimercaptopropanol, suggesting that vicinal dithiols may be required. Inhibition by hypophosphite may reflect a competition with formate for a site on the enzyme. At an alkaline pH, alpha-ketobutyrate is degraded to propionate and formate, whereas alpha-ketoglutarate is fermented to succinate, propionate, carbon dioxide, hydrogen, and formate. Formate is exchanged into the carboxyl groups of alpha-ketobutyrate and alpha-ketoglutarate under these conditions. Only traces of alpha-ketovalerate and alpha-ketoisovalerate are fermented at an alkaline pH and the exchange of formate into these compounds is very low.The addition of viologen dyes under the conditions used for formate exchange causes a reduction of pyruvate, alpha-ketobutyrate, alpha-ketovalerate, and alpha-ketoisovalerate to the corresponding alpha-hydroxy acids.

Journal Article↗
PubMed1977

Species distribution and properties of hepatic phenylalanine (histidine):pyruvate aminotransferase.

Hepatic phenylalanine(histidine):pyruvate aminotransferase activity is much higher in the mouse and rat than in other animal species (human, guinea-pig, rabbit, pig, dog and chicken). The activity is elevated in the mouse and rat by the injection of glucagon but not in other species (guinea-pig, rabbit and chicken). The enzyme was purified from the mitochondrial fraction of mouse liver to homogeneity as judged by polyacrylamide disc gel electrophoresis in the presence of dodecylsulphate. With histidine as amino donor, the enzyme was active with pyruvate, oxaloacetate and hydroxypyruvate as amino acceptors but not with 2-oxoglutarate. Effective amino donors were histidine, phenylalanine and tyrosine with pyruvate, and methionine, serine and glutamine with phenylpyruvate. The apparent Km for histidine was about 6.9 mM with pyruvate and that for pyruvate was 21 mM with histidine. The enzyme is probably composed of two identical subunits with a molecular weight of approximately 40000. The pH optimum was near 9.0. Isoelectric focusing of the purified enzyme resulted in the detection of four forms with pI 6.0, 6.2, 6.5 and 6.7, respectively, all of which were responsive to glucagon. These four forms were nearly identical with the purified enzyme before the focusing with respect to physical and enzymic properties. A possible mechanism of this multiplicity is discussed.

Animals↗
PubMed1975

[Studies On Glutamic Pyruvic- And Oxaloacetic Transaminase Of Different Organs Of Ascaris Lumbricoides Suis]

A Study on glutamic pyruvic and oxaloacetic transaminase of different organs(e.g intestine, seminal vesicle, reticular tissue, uterus, ovary, testes) in Ascaris lumbricoides suis have been investigated. The activity of transaminase were determined on the whole homogenates and subcellular fractions separated by differential centrifugation. The activity of glutamic pyruvic and oxaloacetic were assayed by colorimetric method of Reitman-Frankel. The results were obtained as follows: 1. About ninty percent of the glutamic pyruvic and oxaloacetic transaminase in different organs was found to be localized in the supernatant fraction with the separation of differential centrifugation. And it was found that ten percent of glutamic pyruvic and oxaloacetic transaminase exists in the mitochondrial fraction. 2. The specific activity of glutamic oxaloacetic transnaminase in different organs was relatively higher than the glutamic pyruvic transaminase activity.

Journal Article↗
PubMed2000

On-line measurement of intracellular ATP of Saccharomyces cerevisiae and pyruvate during sake mashing.

The concentrations of intracellular ATP of Saccharomyces cerevisiae and pyruvate in a medium were instantaneously increased by pulse addition of glucose during starvation. They were reduced rapidly by alcohol fortification of the medium, accompanied by simultaneous increases of acetaldehyde concentration and inviability of yeast cells. These results were monitored during fermentation of sake mash by an on-line measuring method. Intracellular ATP and pyruvate concentrations were considered to be indicators of the physiological state of the yeast in sake mash. During sake mashing, it was observed that an increase in temperature enhanced the intracellular ATP concentration and the pyruvate production of the yeast. Since pyruvate production was not affected intensely by changes in temperature during cultivation in a glucose-limited chemostat, this effect was thought to be due to the enhanced rates of cell-growth and/or alcohol production. This suggests that the control of mashing temperature during cell growth until about 10% alcohol accumulation is achieved is important for the control of the pyruvate concentration in sake mash.

Journal Article↗
PubMedDate not supplied

[Effect of methylguanidine and guanidinosuccinic acid on pyruvate kinase activity in human red cells].

An effect of methylguanidine and guanidinosuccinic acid on pyruvate kinase activity in human red cells was determined in vitro following a 3-hour incubation at 37 degrees C. The obtained results have shown that methylguanidine in the concentration of 1.8 x 10(-5) M/l inhibits pyruvate kinase activity by 20.8%. Pyruvate kinase activity was statistically significantly inhibited on addition of methylguanidine in the concentration of 5.4 x 10(-5) M/l whereas higher concentrations have no such an effect Guanidinesuccinic acid exerted similar but weaker effect on the activity of pyruvate kinase in human red cells. Mixture of methylguanidine (5.4 x 10(-5) m/l) and guanidinesuccinic acid (2.8 x 10(-5) M/l) does not affect pyruvate kinase activity in normal human red cells under identical experimental conditions.

Erythrocytes↗
PubMed1990

Diagnosis of pyruvate kinase deficiency in a transfusion-dependent patient with severe hemolytic anemia.

In a 2-yr old girl a hemolytic anemia was present since birth requiring multiple blood transfusions. Pyruvate kinase deficiency was suspected on the basis of a marginal enzyme activity, but could not be established due to the presence of massive numbers of donor cells in her peripheral blood. However, by density fractionation we succeeded in the isolation of a small fraction of the patient's own cells, in which a severe pyruvate kinase deficiency could be detected. In contrast hexokinase and glucose-6-phosphate dehydrogenase activities were extremely high, which is indicative that a very immature cell population is present in this fraction. In immunofluorescence studies a clear crossreaction was apparent with anti M2-type pyruvate kinase antibodies, whereas only a faint reaction with anti L-type could be detected. Despite the presence of a slight amount of L-type immunoreactive material, the residual activity in the patient's cell fraction could only be attributed to M2-type pyruvate kinase as was shown by cellulose acetate electrophoresis.

Anemia, Hemolytic↗
PubMed1983

Muscle pyruvate oxidation following denervation and reinnervation.

Muscle pyruvate metabolism was studied in rats following sciatic nerve crush. Control studies showed high pyruvate dehydrogenase and lipoamide dehydrogenase enzyme activity in muscle with type 1 fiber predominance (soleus) and low activities in muscle with type 2 fiber predominance (extensor digitorum longus), whereas lactate dehydrogenase was much higher in the latter. Following denervation, both muscles showed a significant reduction in pyruvate dehydrogenase enzyme activity. During reinnervation, muscle with type 2 predominance developed significantly elevated pyruvate oxidation enzyme activities.

Animals↗
PubMed2001

Reaction mechanism for mammalian pyruvate dehydrogenase using natural lipoyl domain substrates.

The pyruvate dehydrogenase (E1) component of the pyruvate dehydrogenase complex (PDC) catalyzes a two-step reaction. Recombinant production of substrate amounts of the lipoyl domains of the dihydrolipoyl transacetylase (E2) component of the mammalian PDC allowed kinetic characterization of the rapid physiological reaction catalyzed by E1. Using either the N-terminal (L1) or the internal (L2) lipoyl domain of E2 as a substrate, analyses of steady state kinetic data support a ping pong mechanism. Using standard E1 preparations, Michaelis constants (Km) were 52 +/- 14 microM for L1 and 24.8 +/- 3.8 microM for pyruvate and k(cat) was 26.3 s(-1). With less common, higher activity preparations of E1, the Km values were > or =160 microM for L1 and > or =35 microM for pyruvate and k(cat) was > or =70 s(-1). Similar results were found with the L2 domain. The best synthetic lipoylated-peptide (L2 residues 163-177) was a much poorer substrate (Km > or =15 mM, k(cat) approximately equals 5 s(-1); k(cat)/Km decreased >1,500-fold) than L1 or L2, but a far better substrate in the E1 reaction than free lipoamide (k(cat)/Km increased >500-fold). Each lipoate source was an effective substrate in the dihydrolipoyl dehydrogenase (E3) reaction, but E3 had a lower Km for the L2 domain than for lipoamide or the lipoylated peptides. In contrast to measurements with slow E1 model reactions that use artificial acceptors, we confirmed that the natural E1 reaction, using lipoyl domain acceptors, was completely inhibited (>99%) by phosphorylation of E1 and the phosphorylation strongly inhibited the reverse of the second step catalyzed by E1. The mechanisms by which phosphorylation interferes with E1 activity is interpreted based on accrued results and the location of phosphorylation sites mapped onto the 3-D structure of related alpha-keto acid dehydrogenases.

Acetylation↗
PubMed1999

Regulatory effect of thiamin pyrophosphate on pig heart pyruvate dehydrogenase complex.

The kinetic behavior of pig heart pyruvate dehydrogenase complex (PDC) containing bound endogenous thiamin pyrophosphate (TPP) was affected by exogenous TPP. In the absence of exogenous TPP, a lag phase of the PDC reaction was observed. TPP added to the PDC reaction medium containing Mg2+ led to a disappearance of the lag phase, inducing strong reduction of the Km value for pyruvate (from 76.7 to 19.0 microM) but a more moderate decrease of Km for CoA (from 12.2 to 4.3 microM) and Km for NAD+ (from 70.2 to 33.6 microM), with no considerable change in the maximum reaction rate. Likewise, thiamin monophosphate (TMP) decreased the Km value of PDC for pyruvate, but to a lesser extent (from 76.7 to 57.9 microM) than TPP. At the unsaturating level of pyruvate, the A50 values for TPP and TMP were 0.2 microM and 0.3 mM, respectively. This could mean that the effect of TPP on PDC was more specific. In addition, exogenous TPP changed the UV spectrum and lowered the fluorescence emission of the PDC containing bound endogenous TPP in its active sites. The data obtained suggest that TPP plays, in addition to its catalytic function, the important role of positive regulatory effector of pig heart PDC.

Adenosine Diphosphate↗
PubMed1996

Ursodeoxycholic acid treatment lowers the serum level of antibodies against pyruvate dehydrogenase and influences their inhibitory capacity for the enzyme complex in patients with primary biliary cirrhosis.

A two-year randomized, double-blind, placebo-controlled clinical trial used paired serum samples from 122 patients with primary biliary cirrhosis to compare the effect of ursodeoxycholic acid and colchicine on their immune parameters. IgG antibodies to pyruvate dehydrogenase, the major autoantigen in primary biliary cirrhosis, were determined by enzyme-linked immunosorbent assay and immunoblot; enzyme inhibition assay against pyruvate dehydrogenase was used to test the changes of the functional reactivity of the serum autoantibodies. Treatment with ursodeoxycholic acid decreased both the level of IgG antibodies to pyruvate dehydrogenase (P < 0.01) and the inihibitory titer of the sera for pyruvate dehydrogenase (P < 0.01). Treatment with colchicine or placebo showed no statistically significant changes in either the antibody levels or the inhibitory titers. Ursodeoxycholic acid thus alters the immune parameters of patients with primary biliary cirrhosis. The mechanism of these changes needs further investigation.

Antibodies↗
PubMed1977

Pyruvate kinase mutants of Saccharomyces cerevisiae: biochemical and genetic characterisation.

Mutants of Saccharomyces cerevisiae lacking pyruvate kinase (EC 2.7.1.40) are described. These have less than 0.5% of the pyruvate kinase activity of the wild type. All the other glycolytic enzymes are present in normal amounts in these mutants. The mutation is recessive and segregates in diploids as a single gene. Five alleles examined fail to complement one another. Tetrad analysis and mitotic recombination data place the mutation on the left arm of chromosome I distal to cys 1. The majority of single-step spontaneous revertants on glucose regain the enzyme activity fully and this activity appears, by a number of criteria, to be due to the same enzyme present in the wild type. Some of these revertants become nuclear petites. The mutants do neither grow on nor ferment sugars but do grow on ethyl alcohol or pyruvate. Glucose addition to cultures growing on alcohol arrests growth until glucose is exhausted. The steady state rate of glucose utilization is slower than in the wild type. This is associated with the accumulation of as much as 5 micronmoles P-enolpyruvate per g wet weight of cells and proportional amounts of 2-P-glyceric and 3-P glyceric acids. The mutation is believed to involve some regulatory element in the synthesis of pyruvate kinase.

Chromosome Mapping↗
PubMed1988

"Cerebral" lactic acidosis: defects in pyruvate metabolism with profound brain damage and minimal systemic acidosis.

Six patients are described with a combination of early onset of neurological symptoms, gross cerebral changes and elevated concentrations of pyruvate and lactate in cerebrospinal fluid. Although at least five of the six patients appear to have a generalised defect in pyruvate metabolism, reflected in deficient pyruvate dehydrogenase activity in cultured fibroblasts, systemic acidosis was not a problem clinically and blood pyruvate and lactate concentrations were only slightly raised. The localisation of significant clinical and biochemical problems to the central nervous system, coupled with the difficulties in making the diagnosis if analysis of cerebrospinal fluid (CSF) is not performed, lead us to term this condition "cerebral" lactic acidosis.

Acidosis, Lactic↗
PubMed1981

[Postmortem changes in the perilymphatic lactate and pyruvate concentrations of guinea pigs. (author's transl)].

Lactate and pyruvate of perilymph (PL) were studied 30, 60, and 120 min postmortem. During this period the mean lactate concentration of scala tympani and scala vestibuli increased from 4.8 mmol/l found intravitally to 17.8 and 15.1 mmol/l, respectively, whereas pyruvate decreased from an average of 0.33 to 0.10 mmol/l (fig. 1). These inverse changes of concentration yield postmortem lactate/pyruvate quotients which are more than one order of magnitude higher than the quotients found intravitally (Table 1). In comparative tests of blood samples carried out 30, 60, and 120 min after the sampling (Fig.1), the lactate increase was found to be markedly lower than in postmortem PL. The substantial metabolite changes in PL seem to be caused by glycolytic activity of all cochlear structures that are in direct contact with PL. The decrease of pyruvate level is probably due to a shift of the lactate-pyruvate equilibrium (lactate dehydrogenase system) in PL. The blood vessels in the perilymphatic space can be neglected as postmortem metabolite source of PL.

Animals↗
PubMed1988

Marked secretion of pyruvate in human duodenal juice stimulated with pancreozymin or secretin.

Pyruvate and lactate in duodenal aspirates were investigated to determine whether they are excreted from human pancreas as substrates for alkaline secretion as is bicarbonate. Secretion of these acids was compared with that of another organic acid, citrate, which is thought to be excreted in close relationship to digestive enzymes. All acids were assayed in the fluid obtained from 11 subjects without pancreatic diseases, before and after sequential intravenous injections of 1 unit/kg pancreozymin and 1 unit/kg secretin. Pyruvate concentrations were markedly increased by each stimulation, especially by secretin, and the cumulative excretions of pyruvate and bicarbonate after secretin stimulation were significantly correlated among the subjects. In contrast, lactate concentrations, although high just after administration of pancreozymin, declined to a considerable extent following each injection, rather similar to those of protein or citrate. These data suggest that pyruvate may be secreted from human pancreatic duct cells similar to bicarbonate secretion through mechanisms related to alkaline secretion.

Adult↗
PubMed1992

Prenatal diagnosis of systemic disorders of the respiratory chain in cultured amniocytes and chorionic villus fibroblasts by studying the formation of lactate and pyruvate from glucose.

Formation of lactate and pyruvate from glucose was studied in cultured amniocytes and chorionic villus fibroblasts from controls, either untreated or treated with azide, an inhibitor of cytochrome c oxidase, or other inhibitors of the mitochondrial respiratory chain. Amniocytes with an established cytochrome c oxidase deficiency were also investigated. Control amniocytes treated with azide as well as cytochrome c oxidase deficient amniocytes displayed strongly increased lactate-to-pyruvate ratios after incubation with glucose, compared to control cells. Elevated lactate-to-pyruvate ratios were also found in chorionic villus fibroblasts in which complexes I, III or IV were inhibited by rotenone, antimycin or azide, respectively. We conclude that measurement of lactate and pyruvate production from glucose in cultured amniocytes and/or chorionic villus fibroblasts allows adequate prenatal diagnosis of systemic cytochrome c oxidase deficiency and presumably of other systemic deficiencies of mitochondrial respiratory chain enzymes.

Amnion↗