Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitochondria isolated from spontaneous and transplanted mammary adenocarcinomas of two strains of mice were compared, by various biochemical criteria, to mitochondria from mammary glands of midpregnant or hormonally stimulated, cancer-free mice. The specific activities of several mitochondrial enzymes including cytochrome oxidase, alpha-glycerophosphate oxidase, and succinate dehydrogenase were twofold to threefold lower, whereas the activity of monoamine oxidase was two fold higher in tumor mitochondria. Malate dehydrogenase, adenylate kinase, and NADH oxidase showed similar levels of activity in tumor and midpregnant mammary gland mitochondria. In addition, mitochondrial polypeptide composition was analyzed by electrophoresis on sodium dodecyl sulfate-urea polyacrylamide gels. Midpregnant mammary gland and mammary tumor mitochondria were similar in polypeptide composition; however, several differences were observed. A high-molecular-weight polypeptide, present in mid-pregnant mammary gland mitochondria was absent from tumor mitochondria. Also, tumor mitochondria contained an additional high-molecular-weight polypeptide not found in the midpregnant mammary gland. There were numerous differences in the relative proportions of many polypeptides common to both tumor and midpregnant mammary gland mitochondria.
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PMID:Biochemical studies on mitochondria isolated from Normal and Neoplastic Tissues of the Mouse Mammary Gland. 17 82

1. The hepatotoxic effects of heroin and methadone, and the effect of ethanol on opioid-induced hepatotoxicity, have been investigated in human cultured hepatocytes. Hepatocytes pretreated with 50 and 100 mM ethanol were exposed to increasing concentrations of heroin and methadone. 2. Cytotoxicity was evaluated by measuring leakage of intracellular lactate dehydrogenase, and by assessment of hepatocyte mitochondrial succinate dehydrogenase. The half-maximal cytotoxic concentration of heroin for human hepatocytes (TC50) was decreased by 70-55% by pre-exposure to 50 mM ethanol, and that for methadone was decreased by 60-40%. 3. Metabolic functions of human hepatocytes were significantly impaired at concentrations of opioids that had shown little cytotoxicity. Ethanol potentiated opioid-induced hepatotoxicity; concentrations of heroin and methadone that had little or no effect on hepatocyte metabolism in the absence of ethanol caused a significant decrease in urea synthesis rate, metabolism of glycogen and depletion of the intracellular GSH pool after ethanol pretreatment. 4. The increase in toxicity of heroin and methadone produced by ethanol is concomitant with a 40% increase in cytochrome P-450 levels of the pretreated hepatocytes.
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PMID:Potentiation of heroin and methadone hepatotoxicity by ethanol: an in vitro study using cultured human hepatocytes. 152 68

The present investigation was undertaken to examine the biochemical changes occurring in blood and tissues of Landrace pigs given intravenously 2 mg selenium/kg b.w. as either sodium selenite or dimethylselenide. NADP-isocitric dehydrogenase, lactic dehydrogenase and succinic dehydrogenase activities were evaluated in subcellular fractions from liver, heart (right and left ventricle) kidney and longissimus dorsi. Other tested parameters included plasma cations and proteins, blood urea nitrogen, hematocrit as well as selected serum enzymes. The marked inhibition of succinic dehydrogenase along with the rise of the two other dehydrogenases and the modification of the plasma cation profile suggest that in swine sodium selenite may act by determining a shift toward anaerobiosis accompanied by alterations in cell membrane permeability. Comparatively, dimethylselenide was found to affect the tissue enzymes to a similar but less severe extent and appeared devoid of significant effects on the remaining parameters. The possible relationships between the cardiovascular alterations brought about by sodium selenite (described elsewhere) and the observed biochemical changes in the present study are finally discussed.
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PMID:Pathogenesis of sodium selenite and dimethylselenide acute toxicosis in swine: tissue and blood biochemical changes. 215 34

The biochemical consequences of moderate chronic ethanol ingestion has been scarcely investigated in spite of the fact that most of the human population drinks ethanol on a moderate basis. This paper describes some metabolic effects produced by moderate ethanol consumption. The substitution of drinking water in rats for a 10% ethanol solution during 4 weeks resulted in: a) a decrease of blood urea and citrulline synthesis in liver mitochondria; b) a slight inhibition in state 3 and state 4 respiration either with glutamate-malate as substrates or succinate as substrate; c) no change in ADP/O ratio with succinate but slight increase with glutamate-malate; d) a reduction of the cytochrome oxidase activity and cytochromes a+a3 content; e) a 42% increase in the succinate dehydrogenase activity and a small but constant increase in the Vmax (no change in the Km) of the adenine nucleotide translocase activity in liver mitochondria. These results show that even moderate, but continuous ethanol ingestion, produces metabolic responses that must be carefully evaluated to define health risk in larger human groups.
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PMID:Effects of moderate chronic ethanol consumption on rat liver mitochondrial functions. 254 37

1. The kinetic and metabolic properties of lactate dehydrogenase isoenzyme LDH(x) from human sperm cells and rat testes were studied. 2. LDH(x) shows a sensitivity to inhibition by stilboestrol diphosphate, urea and guanidinium chloride different from that of the LDH-H(4) and LDH-M(4) isoenzymes. 3. About 10 and 20% of the total lactate dehydrogenase activity of testes and sperm cells respectively were associated with particulate fractions. In sperm cells 11% was localized in the middle piece and 18.8% in the head fraction. LDH(x) was found in all particulate fractions of sperm cells. The middle piece contained 41.0% of total LDH(x) activity and showed high succinate dehydrogenase activity. 5. The pH-dependence of lactate/pyruvate and NAD(+)/NADH concentration ratios were estimated. Lactate dehydrogenase in sperm cells has maximal activity with NADH as coenzyme at pH7.5 and with NADPH as coenzyme at pH6.0. At pH6.0 a 10% greater oxidation of NADPH than of NADH was found. At acid pH lactate hydrogenase may function as an enzyme bringing about transhydrogenation from NADPH to NAD(+). 6. In agreement with the stoicheiometry of the lactate de- hydrogenase reaction, the lactate/pyruvate concentration ratio decreased with increasing pH. 7. The lactate/pyruvate and NAD(+)/NADH concentration ratios were estimated with glucose, fructose and sorbitol as substrates and as a function of time after addition of these substrates. During a 20min. period after the addition of the substrates, changes in lactate/pyruvate and NAD(+)/NADH concentration ratios were noticed. Increasing concentration of the substrates mentioned gave rise to asymptotic increases in lactate and pyruvate. 8. Sorbitol did not act as a substrate for LDH(x). 9. The findings described are consistent with the idea that LDH(x) is different from other known lactate dehydrogenase isoenzymes, but that it has a metabolic function similar to that of the isoenzymes of other tissues.
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PMID:Lactate dehydrogenase isoenzymes of sperm cells and tests. 430 63

Cefotiam (CGP 14221/E; SCE 963), a semisynthetic cephalosporin, was administered as a single dose by i.v. injection to rats l(up to 1.8 g/kg body-weight) and rabbits (up to 1.7 g/kg body-weight). Cephaloridine served as positive control (1.0 and 0.75 g/kg in rats; 0.3 and 0.28 g/kg in rabbits). The animals were sacrificed 24 h after injection and the kidneys preserved for routine histology and enzyme histochemistry (alkaline phosphatase, aminopeptidase, succinate dehydrogenase, esterase). Serum samples (Na+, K+, Cl-, urea, creatinine, LDH, alkaline phosphatase) and 24-h urine (Na+, K+, Cl-, urea, creatinine, protein, LDH, aminopeptidase) were analysed before and 24 h after injection. Minimal, irregularly scattered, degenerative changes in the proximal tubules which were not dose-dependent in degree were observed in rat kidneys following cefotiam injection. A slight dose-dependent degeneration in up to 50% of proximal tubular cells with loss of brush-border membrane enzyme activity was observed in rabbit kidneys. In both animal species the ability to concentrate urine was retained and urea and creatinine serum levels hardly affected. Following cefotiam injection a dose-dependent 4-fold excretion of urinary protein but not of LDH was observed in rabbits only. By contrast, cephaloridine caused extensive degeneration and necrosis in up to 90% of proximal tubular cells in both rats and rabbits, which was accompanied with formation of enzymically active hyaline casts, loss of urine-concentrating capacity of the kidney, elevated serum levels of urea and creatinine and an increased urinary excretion of LDH (60-fold in rats, 20-fold in rabbits) and protein (3-fold in rats, 10-fold in rabbits). Histochemistry and electron microscopy of rabbit kidneys suggested a loss of microvilli from proximal tubule cells by endocytosis and thus degeneration following injection of large doses of cefotiam, whereas cell disruption and necrosis prevailed after cephaloridine. The action of cefotiam on the proximal tubule cells is, therefore, not only quantitatively but possibly also qualitatively different from that of cephaloridine. Semiquantitative evaluation of tubular injuries in alkaline phosphatase-stained kidney sections and measurements of LDH and protein content in 24-h urine samples were advantageous in determining the quantity and the quality of nephrotoxic effects.
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PMID:Nephrotoxicity of cefotiam (CGP 14221/E) in rats and rabbits. 627 Oct 94

Intramuscular injections of the title drug in a dose of 5 mg/kg (5% of the LD50) during 10 days produced in the liver and blood serum of white rats a decrease in the activity of glucokinase, succinate dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, glutathione reductase, ATPase and ceruloplasmin. The urea content in total phospholipids rose, whereas the content of triglycerides and hexosamine diminished. Ten and 20 days after the drug was discontinued the majority of these characteristics returned to normal. The activity of glucosophosphate isomerase, transketolase, glucose-6-phosphatase, fructose-1,6-diphosphatase and lactate dehydrogenase as well as the content of total cholesterol, free fatty acids, tyrosine, hydroxyproline, total protein, RNA and DNA remained unchanged.
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PMID:[Effect of decane-1,10-bis[acetoxy-(N, N)-dimethyl-(N)-(diphenylmethoxy-2-ethyl) ammonium] dichloride on metabolism in white rats]. 651 57

1. The factors affecting the pathway of glutamate oxidation were studied in isolated rat-liver mitochondria in incubations of 2-3 min. 2. It was found that bicarbonate at a physiological concentration has a profound effect on the pathway of glutamate oxidation. Ammonia formation via glutamate dehydrogenase is stimulated by bicarbonate [from 5.48 +/- 0.29 (n = 10) to 9.57 +/- 0.73 (n = 8) nmol X min-1 X mg protein-1], whereas aspartate formation via the transamination pathway is inhibited [from 38.41 +/- 2.24 (n = 9) to 24.56 +/- 3.28 (n = 6) nmol X min-1 X mg protein-1]. 3. Bicarbonate has no effect on the rate of transport of glutamate via the glutamate-hydroxyl translocator. 4. The interaction of bicarbonate with the pathway of glutamate oxidation occurs primarily at the level of succinate dehydrogenase, due to competitive inhibition of the enzyme by bicarbonate. 5. Inhibition by bicarbonate of the transamination pathway leads to a decrease in intramitochondrial 2-oxoglutarate, so that the deamination pathway is stimulated. 6. Using an equation which describes flux through glutamate dehydrogenase kinetically, it could be shown that the bicarbonate-induced decrease in intramitochondrial 2-oxoglutarate quantitatively accounts for the enhanced rate of deamination. 7. It is concluded that in the intact liver flux through glutamate dehydrogenase is sufficient to account for the ammonia formation required for urea synthesis from substrates such as alanine.
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PMID:Bicarbonate and the pathway of glutamate oxidation in isolated rat-liver mitochondria. 685 31

1. A long-term experiment was made with the Rumen Simulation Technique (Rusitec), in which the fermentation of a mixed ration of hay (10 g/d) and bruised barley (5 g/d) was compared with the fermentation of the same diet in the presence of 2, 10 and 50 mg monensin/d. 2. Monensin depressed the production of acetic and butyric acids, markedly increased the production of propionic acid and virtually, eliminated the production of isovaleric acid. The production of methane was decreased in the presence of monensin, but this decrease could be accounted for entirely by the changes in the production of volatile fatty acids and redistribution of metabolic hydrogen. 3. The digestibility of dry matter (DM) in the rations declined in the presence of monensin. Determinations of the rates of digestion showed that the digestion of the readily-fermented food in the initial stages was not affected by monensin, but that at 24 h digestion had been inhibited by monensin. The inhibition was due entirely to its effect on the digestion of the fibrous components. Digestion of non-fibrous material was not affected. 4. The efficiency of microbial growth, expressed as g dry weight/mol ATP formed (YATP) and in terms of DM digested, tended to be increased by monensin. This however occurred only at high, non-practical doses. 5. Urease (EC 3. 5. 1. 5) was induced by the addition of urea of the fermentation, but monensin had no effect on urease activity. Although monensin increased the activity of protease in washed suspensions, more food protein apparently escaped degradation. This may have been due to decreased deaminative activity. 6. Monensin altered the microscopic appearance of the fermentation fluid, and changed the activity of some enzymes in sonicated extracts, including alkaline phosphatase (EC 3. 1. 3. 1), acetate kinase (EC 2. 7. 2. 1) and succinate dehydrogenase (EC 1. 3. 99. 1). These results are discussed in terms of known sensitivities of rumen microbes to monensin and their contribution to the fermentation as a whole.
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PMID:Effect of monensin on the fermentation of basal rations in the Rumen Simulation Technique (Rusitec). 702 Jul 49

The temporal relationship between the effect of glucagon on respiratory functions and the changes in metabolites related to gluconeogenesis has been studied. Mitochondria prepared from hepatocytes after incubation with glucagon for 1 min already displayed a maximal stimulation of state-3 respiration. The increase in succinate dehydrogenase activity was almost fully expressed 3 min after glucagon. With respect to the utilization of pyruvate, 2-oxoglutarate and glutamate, glucagon produced a significant effect within 1 min. The rate of this decrease was linear for about 3 min slowing down thereafter. The stimulation of glucose production from lactate became significant within 1 min and remained constant up to 15 min. The influence of glucagon on the mitochondrial redox state also was an early event. It was maximally shifted to the more reduced state within 2 min and declined within 15 min. Under the conditions employed no effect of glucagon on urea synthesis or branched-chain amino acid release up to 15 min incubation time was discernible. Glucagon influenced the respiratory parameters virtually independent of Ca2+, in contrast to its action on intermediary metabolism. As to the hormone specificity, no enhancement of state-3 respiration and succinate dehydrogenase activity was caused by phenylephrine or isoproterenol. From the time course studies presented, it appears that the mitochondrial effects of glucagon might be causally interrelated with the regulation of gluconeogenesis. Moreover, our results indicate that the stimulation of state-3 respiration represents the earliest, specific action of glucagon at the mitochondrial level.
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PMID:Early kinetics of glucagon action in isolated hepatocytes at the mitochondrial level. 743 59


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