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:2.3.3.1 (citrate synthase)
4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of chronic embryonic ethanol exposure were evaluated in chick ventricular muscle. Ethanol treatments were administered on embryonic days 11, 13, 15, and 17 and chicks were sacrificed at various time points following treatments. Fluctuations in embryonic blood ethanol levels were examined following treatments. Developmental increases in the activities of mitochondrial enzymes, cytochrome oxidase (CO) and citrate synthase (CS), were observed. Ethanol exposure resulted in a depression in CO activity, but not CS activity. Since, a maximal depression in CO activity was seen with ethanol treatments of 75 mg/100 g, this dosing paradigm was adopted for subsequent experiments. A tissue-specific effect of ethanol was demonstrated as CO activity was unchanged in atrial, liver, pectoralis, and brain tissues. The role of mitochondrial DNA replication and transcription during the developmental up-regulation and ethanol-induced down-regulation of CO activity was evaluated using a cDNA probe for cytochrome oxidase subunit III (COIII). The relative levels of COIII mRNA and mitochondrial DNA (cpm/mg protein) decreased by 3-fold and 4-fold, respectively, across the developmental time course, while CO activity increased by 3.5-fold. Therefore, increases in mitochondrial DNA and mitochondrial mRNA transcripts are unlikely to be responsible for the developmentally-regulated increases in CO activity. Similarly, embryonic ethanol exposure failed to elicit alterations in COIII mRNA levels, indicating that the ethanol-induced depression in CO activity was not transcriptionally regulated. However, ventricular mitochondrial DNA concentrations were elevated in ethanol-treated embryos, indicating that ethanol-exposure either directly or indirectly induces mitochondrial DNA replication.
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PMID:Ventricular mitochondrial gene expression during development and following embryonic ethanol exposure. 838 53

It has been hypothesized that some of the functional impairments associated with aging are the result of increasing oxidative damage to mitochondrial DNA that produces defects in oxidative phosphorylation. To test this hypothesis, we examined the enzymes that catalyze oxidative phosphorylation in crude mitochondrial preparations from frontoparietal cortex of 20 rhesus monkeys (5-34 years old). Samples were assayed for complex I, complex II-III, complex IV, complex V, and citrate synthase activities. When enzyme activities were corrected for citrate synthase activities (to account for variable degrees of mitochondrial enrichment), linear regression analysis demonstrated a significant negative correlation of the activities of complex I (p < 0.002) and complex IV (p < 0.03) with age but no significant change in complex II-III or complex V activities. Relative to animals 6.9 +/- 0.9 years old (n = 7), the citrate synthase-corrected activity of complex I was reduced by 17% in animals 22.5 +/- 0.9 years old (n = 6) (p < 0.05) and by 22% in animals 30.7 +/- 0.9 years old (n = 7) (p < 0.01). Similar age-related reductions in the activities of complexes I and IV were obtained when enzyme activities were corrected for complex II-III activity. These findings show an age-associated progressive impairment of mitochondrial complex I and complex IV activities in cerebral cortices of primates.
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PMID:Age-dependent impairment of mitochondrial function in primate brain. 847 11

A condition similar to insulin-dependent diabetes mellitus (IDDM) was induced in male CD-1 mice by injection of streptozotocin (STZ). Five weeks after treatment, the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles were isolated for analysis. Phosphorous metabolites were quantified by 31P-NMR and HPLC, native myosin was characterized electrophoretically, and activities of metabolic enzymes were measured spectrophotometrically. Relative to control animals, STZ-diabetes resulted in a significant 32% decrease in the FM1 isoform of myosin in EDL and a 24% decrease in IM myosin of SOL. Mass-specific activities of phosphofructokinase, citrate synthase, and cytochrome oxidase were significantly lower in SOL from STZ-diabetic mice than in controls by 23, 18, and 36%, respectively. Intracellular ATP was significantly lower in SOL from STZ-diabetic mice than in controls (3.44 +/- 0.20 mumol g-1 wet weight vs. 4.61 +/- 0.20 mumol g-1, respectively), as was creatine phosphate (11.98 +/- 0.80 mumol g-1 wet weight vs. 14.22 +/- 0.44 mumol g-1). In contrast to results from SOL, there were no significant changes in phosphorus metabolites or enzyme activity in EDL. These results show that the effects of IDDM on levels of phosphorus containing metabolites and maximal activities of key regulatory enzymes in muscle are markedly fiber-type specific. It is suggested that the muscle type-specific effects of STZ-diabetes may be a consequence of differential accumulation of intracellular fatty acids.
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PMID:Responses of mouse fast and slow skeletal muscle to streptozotocin diabetes: myosin isoenzymes and phosphorous metabolites. 859 19

This study compared the acute effects of 5 ppm hydrogen sulfide (H2S) inhalation (50 % of its occupational exposure limit) on the biochemical properties of skeletal muscle in exercising men and women. Twenty-five healthy volunteers, 13 men and 12 women, completed two 30-minute submaximal tests at 50% of their predetermined maximal aerobic power (VO2max) while breathing 0 ppm (control) or 5 ppm H2S from a specially designed flow system in a single-blind manner. Immediately after exercise, biopsies were obtained from the vastus lateralis muscle under local anaesthesia. They were subsequently analyzed for concentrations of the following markers of anaerobic and aerobic metabolism: lactate (La), lactate dehydrogenase (LDH), citrate synthase (CS), and cytochrome oxidase (CytOx). Repeated measures analysis of variance indicated that in men, the CS concentration decreased significantly (p = 0.006) as a result of H2S exposure. There was also a tendency for their La and LDH concentrations to increase and CytOx concentration to decrease in the presence of H2S, but these changes were not significant (p > 0.05). In women no significant changes were observed in any of these biochemical properties. These results suggest that (1) exposure to H2S at 50% of its OEL might inhibit aerobic metabolism during exercise in healthy men, thereby increasing their dependency on anaerobic metabolism; and (2) there could be a significant gender difference in the acute response to sub-OEL exposures of H2S.
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PMID:Effects of 5 ppm hydrogen sulfide inhalation on biochemical properties of skeletal muscle in exercising men and women. 863 17

Numerous data suggest that mitochondrial activity is involved in the regulation of cell growth and differentiation. Therefore, we have studied the changes in mitochondrial activity in avian myoblast cultures (QM7 line) undergoing differentiation or in BrdU-treated, differentiation-deficient cells. As we have previously shown that triiodothyronine and v-erb A expression stimulate myogenic differentiation, we have also observed their influence upon mitochondrial activity. Comparison of control and BrdU-treated myoblasts indicated that precocious differentiation events were associated with a stimulation of citrate synthase and cytochrome oxidase activities. They also induced a transient decrease in mitochondrial membrane potential assessed by rhodamine 123 uptake. In control myoblasts, a general stimulation of mitochondrial activity was recorded at cell confluence, prior to terminal differentiation. These events did not occur in BrdU-treated myoblasts, thus indicating that they were tightly linked to myoblast commitment. Whereas no significant triiodothyronine influence could be detected upon mitochondrial activity, we observed that v-erb A expression significantly depresses the mitochondrial membrane potential in control myoblasts. This action was not observed in BrdU-treated myoblasts, thus suggesting that it involves an indirect pathway linked to differentiation. Moreover, the oncoprotein abrogated the decrease in E2-PDH subunit level observed at cell confluence. These data underline that changes in mitochondrial activity occurred prior to myoblast terminal differentiation and could be involved in the processes regulating myogenesis. In addition, they provide the first evidence that the v-erb A oncoprotein influences mitochondrial activity.
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PMID:Changes in mitochondrial activity during avian myoblast differentiation: influence of triiodothyronine or v-erb A expression. 870 59

The activities of enzymes related to energy metabolism in the gastrocnemius and soleus muscles in young-adult (4 months), mature (12 months) and senescent (24 months) rats were compared after 72 h of continuous exposure to normobaric hypoxia or normoxia after alpha-adrenergic antagonist nicergoline or saline solution had been given intraperitoneally for 30 consecutive days. The maximum rates (Vmax) of the following enzyme activities in the crude extract and/or the mitochondrial fraction of each muscle specimen were evaluated: (1) for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase; (2) for the tricarboxylic acid cycle; citrate synthase and malate dehydrogenase; (3) for the electron transfer chain; cytochrome oxidase; and (4) for the NAD+/NADH redox state: total NADH cytochrome c reductase. The significant differences between the enzyme activities at different ages or under different experimental conditions in the two tissue preparations of the two muscles were determined by ANOVA. MCA and ETA were used to evaluate the net effects of the experimental conditions. Ageing did not seem to affect the soleus and gastrocnemius muscles in the same way. Changes were seen only in the glycolytic pathway enzymes in the crude extract from the gastrocnemius muscle. In the soleus muscle changes in enzyme activities as a function of ageing were also found in the mitochondrial fraction. We also found that hypoxia caused greater changes in 12-month-old rats than in those of other ages (especially in the enzyme activities of the gastrocnemius muscle). Finally out data show that only in certain cases was the pharmacological treatment able to modify the influence of hypoxic conditions on the levels of enzyme activities, regardless of the age of animals.
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PMID:Effects of hypoxia on enzyme activities in skeletal muscle of rats of different ages. An attempt at pharmacological treatment. 873 89

We studied two diagnostic aspects of fatal infantile defects of the mitochondrial respiratory chain: the age dependence of muscle mitochondrial enzyme activities and the reliability of diagnosis from autopsy samples. In morphologically normal quadriceps muscle samples of 46 children between the ages of 3 days and 15 years, activities of complex I plus III (NADH:cytochrome c oxidoreductase) and complex II plus III (succinate:cytochrome c oxidoreductase) increased 2-fold during the first three years of life, while that of complex II (succinate dehydrogenase), complex IV (cytochrome c oxidase), and citrate synthase did not show significant correlation with age. We suggest that these changes are related to age and stress the importance of strictly age-matched controls when diagnosing a mitochondrial disease of early childhood. The value of autopsy samples in diagnostic studies was evaluated by comparing mitochondrial enzyme activities in quadriceps muscle from autopsies and from surgical biopsies. In quadriceps muscle mitochondria, all the enzyme activities studied remained stable for at least 3 h after death. Using age-matched controls and autopsy samples, we diagnosed a respiratory chain enzyme deficiency in two infants, and the defects were confirmed in cultured skin fibroblasts.
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PMID:Diagnosis of fatal infantile defects of the mitochondrial respiratory chain: age dependence and postmortem analysis of enzyme activities. 874 50

Specific mitochondrial enzyme activities, mitochondrial DNA copy number, and mRNA levels were measured in heart, brain, and liver tissues of a group of alcohol-fed rats and compared with a control group. The results show a significant increase in mitochondrial enzyme activities (citrate synthase, complex IV, complex III, complex I, and complex V), as well as an increase in mitochondrial DNA in the cardiac tissue of the alcohol-fed animals. These data are indicative of an increase in mitochondrial number in the cardiac tissue that may occur as the result of an adaptive response to the alcoholic insult. However, in the liver and brain of the alcohol-treated rat, specific mitochondrial activities were decreased, in particular, complex III and ATP synthase, whereas levels of other mitochondrial enzymes (e.g., citrate synthase, specific mitochondrial transcripts, and mitochondrial DNA levels) do not seem to be affected. These data suggest that a tissue-specific response to alcohol exists that may have a common molecular mechanism in brain and liver, but is different in the heart.
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PMID:Heart mitochondria response to alcohol is different than brain and liver. 874 11

1. Chronic fatigue syndrome is characterized by muscle fatigue and pain at rest, symptoms which are usually exacerbated with exercise. Although various studies have shown minor, non-specific morphological and biochemical changes in muscle of patients with chronic fatigue syndrome, no consistent defect has been identified. Some have suggested that an enteroviral infection in muscle may cause the chronic muscle fatigue seen in patients with chronic fatigue syndrome, with acute infection directly and irreversibly impairing mitochondrial function, and persistent infection depressing muscle protein synthesis and metabolism. 2. To clarify the involvement of enterovirus infection in chronic fatigue syndrome, muscle biopsies from a group of patients with chronic fatigue syndrome were examined for the presence of enteroviral RNA by reverse transcriptase-polymerase chain reaction techniques in relation to functional studies of muscle mitochondria and the muscle RNA/DNA ratio. 3. Fifty-eight percent of patients reported an uncharacterized 'viral infection' before the onset of their illness, but none of the muscle samples from 34 patients contained detectable amounts of enteroviral RNA. Muscle tissue had a general reduction in the RNA/DNA ratio and mitochondrial enzyme activities with no specific abnormality in the activity of enzymes encoded partially on the mitochondrial genome (cytochrome-c oxidase) or nuclear genome (citrate synthase, succinate reductase). 4. These data provide no evidence of an enteroviral infection in muscle of patients with chronic fatigue syndrome, although this does not exclude a role of enterovirus in initiating the disease process. The general reduction in RNA/DNA ratio and mitochondrial enzyme activities is consistent with a general reduction in habitual activity.
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PMID:Investigation by polymerase chain reaction of enteroviral infection in patients with chronic fatigue syndrome. 877 36

The time course (age 0-8 weeks) of the enzyme activities of respiratory chain complexes I, III and IV and of citrate synthase, and the cell mitochondrial/nuclear DNA content ratio were studied in Drosophila subobscura. The activities of the three respiratory complexes decreased with age, but with different kinetics. The activities of complexes I and III remained nearly stable between weeks 0 and 3 (falling by 6% and 15%, respectively), and then gradually decreased; after 8 weeks residual activities were about 50% of the initial value for complexes I and III. The activity of complex IV fell in the first week, decreasing continually to week 8, where residual activity was 30% of the initial value. No significant age-related change in citrate synthase activity was observed. Mitochondrial DNA (measured by mitDNA/nucDNA) increased linearly up to week 5 (2.6-fold) and then dropped by 40% in week 6 though it remained higher than initial values.
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PMID:Changes in the respiratory chain complexes activities and in the mitochondrial DNA content during ageing in D. subobscura. 878 73


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