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

---

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

1. Biopsies of the extensor hallucis longus (EHL) and gastrocnemius (G) muscles of four captive black bears (Ursus americanus) were obtained prior to denning (PRE), during denning (DEN) and following the Spring arousal (POST). 2. Glycogen, triglyceride and protein concentrations did not differ significantly between the three groups. Likewise, the activity of citrate synthase, a mitochondrial oxidative enzyme, was not significantly different between the three groups. 3. DNA concentrations in DEN samples increased 30% compared to other groups while RNA concentrations were significantly elevated in POST samples. The RNA/DNA ratios were significantly depressed during DEN. 4. These results suggest a degree of muscle atrophy during DEN, with the potential for an increased capacity for muscle protein synthesis following the Spring arousal.
...
PMID:Biochemical changes in skeletal muscles of denning bears (Ursus americanus). 172 46

We investigated the role of thyroid hormone in the postnatal development of Ca2+ transport activity of sarcoplasmic reticulum in skeletal muscle (m. gastrocnemius-plantaris). With a Ca2+-stat method using the fluorescent dye fura 2 as Ca2+ indicator, we determined the oxalate-supported maximal Ca2+ uptake activity of sarcoplasmic reticulum in whole muscle homogenates from neonatal rats. Expressed per g tissue wet wt, the activity increased nearly 10-fold during the first 8 weeks after birth, following which time a plateau was reached. This development was absent in hypothyroid pups, in which the level of Ca2+ uptake activity remained constant at 10% of the normal adult value for at least 8 weeks. When the mothers were given 0.05% propylthiouracil in the drinking water 1 week before parturition, these pups ceased to grow after 4 weeks, had a reduced muscle protein content and a characteristic cretinous appearance. The effects of hypothyroidism could be reversed by T3 treatment (0.5 micrograms/100 g BW, daily) starting 1 or 6 weeks after birth. Treatment with bovine GH (0.1 or 0.5 IU/100 g BW; daily) starting on day 5 stimulated body growth, particularly of muscle, but was without effect on the failing development of Ca2+ uptake activity. The postnatal rise in citrate synthase and succinate dehydrogenase activities was impaired in the hypothyroid group, but lactate dehydrogenase and creatine kinase activities rose continuously, although at a reduced rate. T3 treatment also reversed these effects of propylthiouracil. At the higher dosage used bovine GH appeared to stimulate the accumulation of creatine kinase. We conclude that the failing postnatal development of sarcoplasmic reticulum Ca2+ transport activity in hypothyroidism is not secondary to the absence of GH, nor is it part of a general, indiscriminate effect, but, rather, that it indicates an absolute requirement of thyroid hormone for this particular aspect of muscle differentiation.
...
PMID:The postnatal development of sarcoplasmic reticulum Ca2+ transport activity in skeletal muscle of the rat is critically dependent on thyroid hormone. 291 9

The glycolytic and aerobic oxidative capacity in skeletal muscle was investigated to reveal if the decrease seen in muscle protein synthesis is accompanied by a fall in the enzymatic capacity to oxidize substrates. Six patients undergoing elective abdominal surgery were investigated by percutaneous muscle biopsies taken before surgery and on the first and third postoperative days. Protein synthesis as assessed by the polyribosome concentration was 40% lower on the third day postoperatively than before surgery (p less than 0.01). The glycolytic and oxidative capacity was evaluated by determining the activity of eight key enzymes in the intracellular oxidative metabolism, namely total creatine kinase (CK), the isozymes CK-MB and mitochondrial CK, lactate dehydrogenase, citrate synthase, aspartate aminotransferase, and phosphofructokinase, and also the concentration of myoglobin. None of these parameters were affected in the immediate postoperative period independently of the provision of nutritional support. It was concluded that the decrease in protein synthesis is not accompanied by a concomitant decline in the enzymatic oxidative capacity in skeletal muscle in the period immediately following elective surgery.
...
PMID:Enzymatic capacity and protein synthesis in human muscle postoperatively. 314 5

Adaptations of skeletal muscle morphology and metabolic enzymes were studied after prolonged training in and exposure to hypobaric (740 -770 mbar) as well as normobaric conditions in rats performing treadmill running training for 10, 21 and 56 days. Animals sacrificed after 91 days served as recovery groups from training and hypobaric exposure for 56 days. The rats were divided into normobaric sedentary (NS) and training (NT) groups and hypobaric sedentary (HS) and training (HT) groups. The weights of extensor digitorum longus (EDL) and soleus (SOL) muscles increased significantly in the 56HS and the 56HT groups compared with the 56NS group, the increase being greatest in the 56HS group. No differences in the mean fibre areas (MFA) of these muscles could be seen, whereas clearly reduced MFAs of type IIA and IIB were observed in the tibialis anterior (TA) muscle. However, fibre area distribution analyses in the EDL and TA muscles showed a higher proportion of larger fibers in the 56HS and 56HT groups than in the respective normobaric groups. On the contrary, in SOL muscles the proportion of smaller fibers was higher in the hypobaric than in normobaric groups at 56 days. Increased activities of citrate synthase and beta-hydroxyacyl-CoA-dehydrogenase in SOL and TA muscles in the 56HT group indicate an increase in oxidative capacity. It is concluded that exposure to, and training in moderate hypobaric conditions leads to a positive muscle protein balance which is reflected in increased muscle weights. However, the sites of increased protein synthesis and the possible hyperplasia remain to be studied further.
...
PMID:Effects of prolonged exposure to and physical training in hypobaric conditions on skeletal muscle morphology and metabolic enzymes in rats. 866 67

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.
...
PMID:Investigation by polymerase chain reaction of enteroviral infection in patients with chronic fatigue syndrome. 877 36

This study is the first to examine the effects of endurance training in an elasmobranch fish. Twenty-four leopard sharks (Triakis semifasciata) were divided randomly into three groups. Eight sharks were killed immediately, eight were forced to swim continuously for 6 wk against a current of 35 cm s-1 (60%-65% of maximal sustainable swimming speed), and eight were held for 6 wk in a tank without induced current. There were no changes due to training in maximal sustainable speed, oxygen consumption rates, percentage of the myotome composed of red and white muscle fibers, blood oxygen-carrying capacity, liver mass, liver lipid, glycogen, and protein concentrations, white muscle protein content, heart ventricle mass, or the specific activities of the enzymes citrate synthase, pyruvate kinase, and lactate dehydrogenase in the heart ventricle. In red myotomal muscle, citrate synthase activity increased 17% as a result of training, but there was no change in muscle fiber diameter. The greatest effects occurred in white myotomal muscle, in which a 34% increase in fiber diameter and a 36% increase in the activities of citrate synthase and lactate dehydrogenase occurred as a result of training. The conditioned fish also had significantly higher growth rates. The observed effects within the myotomal muscle may reflect the higher growth rates of the trained leopard sharks, or they may be a specific response to the increased energetic demands of the training activity, indicating characteristics that limit swimming performance in leopard sharks.
...
PMID:Effects of endurance training in the leopard shark, Triakis semifasciata. 923 9

The activity of glycolytic and oxidative enzymes was monitored in the white muscle of Atlantic cod Gadus morhua experiencing different growth rates. A strong positive relationship between the activity of two glycolytic enzymes and individual growth rate was observed regardless of whether the enzyme activity was expressed as units per gram wet mass, units per gram dry mass or with respect to muscle protein and DNA content. The most sensitive response to growth rate was observed when pyruvate kinase and lactate dehydrogenase activities were expressed as units per microgram DNA, and this may be useful as an indicator of growth rate in wild fish. In contrast, no relationship between the activities of oxidative enzymes and growth rate was observed when cytochrome c oxidase and citrate synthase activities were expressed as units per gram protein. Apparently, the aerobic capacity of white muscle in cod is not specifically increased to match growth rate.
...
PMID:How should enzyme activities be used in fish growth studies? 931 92

Muscle wasting and weakness occur frequently in patients with chronic renal failure. The mechanism(s) by which these abnormalities occur is unclear. We hypothesized that such findings were due to defective muscle protein synthesis. We measured synthetic rates of mixed muscle proteins, myosin heavy chain, and mitochondrial proteins in serial muscle biopsy samples during a continuous infusion of L[1-(13)C]leucine from 12 patients with chronic renal failure and 10 healthy control subjects under identical study conditions. Patients with chronic renal failure have significantly lower synthetic rates of mixed muscle proteins and myosin heavy chain (27 and 37% reductions, respectively, P < 0.05 and P < 0.02). Significant declines in the synthetic rates of muscle mitochondrial protein (27%) (P < 0.05), muscle cytochrome c-oxidase activity (42%) (P < 0.007), and citrate synthase (27%) (P < 0.007) were also observed in patients with chronic renal failure. The synthetic rates of muscle proteins and activity of mitochondrial enzymes were negatively correlated to the severity of renal failure. These results indicate that in chronic renal failure there is a decrease in the synthesis of muscle contractile and mitochondrial proteins and a decrease in muscle mitochondrial oxidative enzymes. Reduced synthetic rate of several muscle proteins is the likely biochemical basis of muscle loss and muscle weakness in people with chronic renal failure.
...
PMID:Reduced synthesis of muscle proteins in chronic renal failure. 1119 53

To establish whether family origin affects the response of the threespine stickleback (Gasterosteus aculeatus) to thermal acclimation, we examined the rates of feeding, growth, and food conversion, relative tissue and organ masses and activities of a mitochondrial and a glycolytic enzyme in pectoral and axial muscle of individually housed fish from six families during acclimation to 8 degrees C and 23 degrees C. Feeding rates differed among families but were consistently higher in warm-acclimated than cold-acclimated fish. Growth rates differed among families. In four families growth was greater at 8 degrees C; these families generally had higher conversion efficiencies at 8 degrees C than 23 degrees C. For two families, growth was greater at 23 degrees C than 8 degrees C and conversion efficiencies did not differ between 8 degrees C and 23 degrees C. Relative tissue and organ masses (percent axial muscle, hepatosomatic, gut and kidney indices) differed with gender and among families (hepatosomatic, gut and kidney indices) but little with acclimation status. In all families and in both muscles, activities of the mitochondrial enzyme, citrate synthase (CS), were increased by cold acclimation. Axial muscle levels of the glycolytic enzyme, lactate dehydrogenase (LDH), were not affected by thermal acclimation or family origin, but were strongly correlated with the hepatosomatic index and axial muscle protein content. Pectoral muscle levels of LDH were affected by family origin which also influenced the response to thermal acclimation. Similar patterns were observed for specific activities and total muscle contents of these enzymes. Stickleback family origin influenced rates of feeding and growth and the thermal sensitivity of growth rates but not the compensatory increase in muscle CS levels with cold acclimation. The differing thermal sensitivities of growth could reflect distinct strategies for the timing of juvenile growth.
...
PMID:Family origin and the response of threespine stickleback, Gasterosteus aculeatus, to thermal acclimation. 1130 36

Improvement of glycemic status by insulin is associated with profound changes in amino acid metabolism in type 1 diabetes. In contrast, a dissociation of insulin effect on glucose and amino acid metabolism has been reported in type 2 diabetes. Type 2 diabetic patients are reported to have reduced muscle oxidative enzymes and VO(2max). We investigated the effect of 11 days of intensive insulin treatment (T(2)D+) on whole-body amino acid kinetics, muscle protein synthesis rates, and muscle functions in eight type 2 diabetic subjects after withdrawing all treatments for 2 weeks (T(2)D-) and compared the results with those of weight-matched lean control subjects using stable isotopes of the amino acids. Whole-body leucine, phenylalanine and tyrosine fluxes, leucine oxidation, and plasma amino acid levels were similar in all groups, although plasma glucose levels were significantly higher in T(2)D-. Insulin treatment reduced leucine nitrogen flux and transamination rates in subjects with type 2 diabetes. Synthesis rates of muscle mitochondrial, sarcoplasmic, and mixed muscle proteins were not affected by glycemic status or insulin treatment in subjects with type 2 diabetes. Muscle strength was also unaffected by diabetes or glycemic status. In contrast, the diabetic patients showed increased tendency for muscle fatigability. Insulin treatment also failed to stimulate muscle cytochrome C oxidase activity in the diabetic patients, although it modestly elevated citrate synthase. In conclusion, improvement of glycemic status by insulin treatment did not alter whole-body amino acid turnover in type 2 diabetic subjects, but leucine nitrogen flux, transamination rates, and plasma ketoisocaproate level were decreased. Insulin treatments in subjects with type 2 diabetes had no effect on muscle mitochondrial protein synthesis and cytochrome C oxidase, a key enzyme for ATP production.
...
PMID:Synthesis rate of muscle proteins, muscle functions, and amino acid kinetics in type 2 diabetes. 1214 50


1 2 3 Next >>

---