Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The biochemical, histochemical, and structural changes induced by endurance training and long-term exposure to high altitude were studied in the diaphragm muscle of rats exposed to simulated altitude (HA: n = 16; Pb = 62 kPa, 463 Torr; 4000 m) and compared to animals maintained at sea-level (SL: n = 16). Half of the animals in each group were trained (T) by swimming for 12 weeks, the other half were kept sedentary (S). Except for a small decrease in type I fibres in the HA-S group (-7%, P < 0.05), in favour of type IIab and type IIb fibres, neither high-altitude exposure nor endurance training had an overall affect on fibre type distribution. The mean fibre cross-sectional area was found to be unaffected by altitude and/or chronic exercise. Capillary density was shown to be increased by both high-altitude exposure (P < 0.02) and training (P < 0.001), whereas capillary growth, estimated by the capillary/fibre ratio, was unaffected in both cases. Following endurance training, a modest increase in citrate synthase was shown to occur to the same extent in the HA-T and SL-T groups (+15% and +16% respectively, NS). Hexokinase increased following training (P < 0.05) and high-altitude exposure (P < 0.001). In normoxic and hypoxic animals, endurance training enhanced the ratio of the heart-specific lactate dehydrogenase isozyme LDH1 to total LDH activity (+59%, P < 0.01; +92%, P < 0.05 respectively). It may be hypothesized that the increased glucose phosphorylation capacity observed in diaphragm muscle contributes to the reduction of glycogen utilization during exercise.
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PMID:Effects of endurance training at high altitude on diaphragm muscle properties. 148 82

Performance tests and measurements of maximal aerobic capacity were performed during the competition period in elite cross-country skiers. Muscle biopsies were taken in the middle of January. Histochemical fibre typing, determination of fibre areas and number of capillaries as well as assays for citrate synthetase (CS), 3-hydroxyacyl coenzyme A dehydrogenase (HAD), lactate dehydrogenase (LDHtot and LDH1-2) were performed on biopsies from the triceps brachii (TRI) and vastus lateralis muscles (VAS). The relative percentage of slow-twitch fibres was 51.3 and 68.6 in TRI and VAS, respectively. The FTa fibre area in TRI was significantly larger than in VAS. No differences were found in the number of capillaries per fibre in TRI (2.7) and VAS (2.5). The number of capillaries per area was significantly lower in TRI (373) as compared to VAS (422). The LDHtot enzyme level was significantly higher in TRI than VAS, while the oxidative enzyme activities (CS and HAD) were significantly lower in TRI as compared with VAS. From all independent variables, only the maximal aerobic power was related significantly to performance time. The difference in maximal aerobic power between the skiers could explain 45% of the total variance in performance.
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PMID:Fibre characteristics and enzyme levels of arm and leg muscles in elite cross-country skiers. 760 14

Adult animal cloning has progressed to allow the production of offspring cloned from adult cells, however many cloned calves die prenatally or shortly after birth. This study examined the expression of three important metabolic enzymes, lactate dehydrogenase (LDH), citrate synthase, and phosphofructokinase (PFK), to determine if their detection in nuclear transfer (NT) embryos mimics that determined for in vitro produced embryos. A day 40 nuclear transfer produced fetus derived from an adult cell line was collected and fetal fibroblast cultures were established and maintained. Reconstructed NT embryos were then produced from this cell line, and RT-PCR was used to evaluate mRNA reprogramming. All three mRNAs encoding these enzymes were detected in the regenerated fetal fibroblast cell line. Detection patterns were first determined for IVF produced embryos (1-cell, 2-cell, 6-8 cell, morula, and blastocyst stages) to compare with their detection in NT embryos. PFK has three subunits: PFK-L, PFK-M, and PFK-P. PFK-L and PFK-P were not detected in bovine oocytes. PFK subunits were not detected in 6-8 cell embryos but were detected in blastocysts. Results from NT embryo RT-PCR demonstrated that PFK was not detected in 8-cell NT embryos but was detected in NT blastocysts indicating that proper nuclear reprogramming had occurred. Citrate synthase was detected in oocytes and throughout development to the blastocyst stage in both bovine IVF and NT embryos. LDH-A and LDH-B were detected in bovine oocytes and in all stages of IVF and NT embryos examined up to the blastocyst stage. A third subunit, LDH-C was not detected at the blastocyst stage in IVF or NT embryos but was detected in all earlier stages and in mature oocytes. In addition, LDH-C mRNA was detected in gonad isolated from the NT and an in vivo produced control fetus. These results indicate that the three metabolic enzymes maintain normal expression patterns and therefore must be properly reprogrammed following nuclear transfer.
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PMID:Genetic reprogramming of lactate dehydrogenase, citrate synthase, and phosphofructokinase mRNA in bovine nuclear transfer embryos produced using bovine fibroblast cell nuclei. 1091 95

The scorpaenid fishes Sebastolobus alascanus and Scorpaena guttata have similar life styles but differ in their depth distributions: S. guttata lives in shallow water (< 180 m); adult S. alascanus occur predominantly on the upper continental slope (400-1200 m) where the oxygen minimum zone (OMZ) prevails and ambient temperature is much colder. Respiratory properties and the activities of heart-tissue enzymes of these species were compared to determine the effect of different thermal and ambient O2 regimens on metabolism. Measured over the appropriate habitat temperature ranges, the oxygen consumption (VO2) of S. alascanus is two to four times less than that of S. guttata. Correction for differences in habitat temperature accounted for over 50% of this reduction. The depth-related decrease in VO2 for these two benthic fishes is less than that observed for pelagic fishes. The VO2 of S. guttata decreases at O2 concentrations below 1 ml/l, whereas the VO2 of S. alascanus is regulated down to 0.3 ml/l. The ventilation frequency (Vf) of both species increases in progressive hypoxia; but at < 0.5 ml/l, the Vf of S. guttata declines, while that of S. alascanus does not. When measured at the same temperature, pH and CO2, the blood-O2 affinity of S. guttata is significantly lower than that of S. alascanus. The anaerobic/aerobic enzyme activity ratio of pyruvate kinase to citrate synthase, which correlates with the ability of heart tissue to tolerate hypoxia, is significantly higher for S. alascanus than S. guttata. Lactate dehydrogenase (LDH) activity in freshly collected S. alascanus is also significantly above that of specimens acclimated to normoxic water in the laboratory. Only the skeletal muscle isozyme of LDH (LDH-A) is present in the heart of S. alascanus, whereas S. guttata has both LDH-A and heart (LDH-B) isozymes. Data for metabolic rate, critical O2 tension, blood oxygen affinity, and heart metabolic enzyme profiles all show essential adaptations of S. alascanus for life in the OMZ.
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PMID:Respiratory, Blood, and Heart Enzymatic Adaptations of Sebastolobus alascanus (Scorpaenidae; Teleostei) to the Oxygen Minimum Zone: A Comparative Study. 2930 May 2