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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tests were carried out on the influence of alloxan-induced diabetes mellitus on the metabolism and the ultrastructure of ovaries of juvenile rats. The diabetes mellitus caused the following changes in the metabolism: reduction in the concentration of ATP and NADPH, increase in the lactate/pyruvate quotient to above 40, reduction in the ATP/ADP quotient to below 1, reduction in the level of activity of the hydrogen-conveying enzymes G-6-P-dehydrogenase, isocitrate dehydrogenase and malate dehydrogenase, increase in the level of activity of the alkaline phosphatase, reduction of the protein content. Ultrastructure: almost complete disappearance of the rough endoplasmic reticulum, shrinkage of the mitochondria, reduction of the cristae and condensation of the matrix. The smooth endoplasmic reticulum remains unchanged, the extent of the Golgi-complex is reduced. Easy removal of the lipid deposits.
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PMID:Metabolism and ultrastructure in ovaries of alloxan-diabetic juvenile rats. 0 67

Isoenzymes NAD-and NaDP MDH were detected in the cardiac muscle of rabbits by disc electrophoresis in polyacrylamide gel. Alloxan diabetes proved to be accompanied by a significant reduction in the activity of mitochondrial NADP MDH (in the reaction of malic decarboxylation) and its increase in cytozol. The activity of NAD-MDH (in the reaction of oxyacetate reduction) was also decreased in various isoenzymes in the myocardium (particularly in the mitochondria) in diabetes. Insulin restored the correlation of the activities of the isoenzymes NAD- and NADP-MDH in the cytostructures of the myocardium disturbed in diabetes.
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PMID:[Activity of NAD- and NADP-dependent malate dehydrogenase isoenzymes in the myocardium of rabbits with alloxan diabetes]. 0 94

The activity of enzymes with a regulatory function in the pathways of glycolysis, gluconeogenesis, NADPH generation and fatty acid synthesis was measured in the placenta and liver of rats. Compared with the liver, a high activity of pyruvate kinase was found in the placenta, indicating a high glycolytic potential; a small capacity for gluconeogenesis was also present and a moderate to low activity of enzymes associated with lipogenesis. The activity of all placental enzymes fell from day 15 to 20 of gestation irrespective of the pathway they represented. The pattern of decline continued when the gestation was prolonged up to day 26 by the administration of chorionic gonadotropin. The rates of activity disappearance over 11 days of gestation differed for each enzyme, with half-lives ranging from 2.7 days for NADP-malate dehydrogenase to 7 days for glucose-6-phosphate dehydrogenase. In contrast, the activity of hepatic enzymes either remained unchanged or showed individual adaptation to the advancing pregnancy. The regression in placental metabolic capacity after day 15 of gestation was also evident by the decrease in glucose uptake and its channelling to lactate, CO2, glycerol and fatty acids. In addition, placental ageing was associated with triglyceride accumulation, mainly due to the decrease in free fatty acid oxidation. Treatment of pregnant rats with several hormones, while markedly affecting the hepatic enzyme activities, failed to induce appreciable changes in the corresponding placental enzymes. This was illustrated in the case of triiodothyronine treatment. Similarly, insulin deficiency induced by streptozotocin failed to elicit adaptive changes in placental enzyme activities typical of diabetes like those occurring in the maternal liver; some converse responses in the placenta were attributed to hyperglycaemia. On the other hand, responses in some fetal liver enzymes were suggestive of fetal hyperinsulinaemia. These observations indicate that placental enzymes are not susceptible to endocrine regulation and imply that placental metabolism is largely independent of the physiopathological alterations affecting the maternal organism. The gradual activity decreases with gestation suggest that the enzyme complement of the placenta, once developed, is designed to last through its limited lifespan without continuous replenishment. Within this context, no mechanism seems to operate to ind1ce the adaptive synthesis of individual enzymes, and the age of the placenta appears to be the primary factor determining its enzyme activity and metabolic performance.
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PMID:Regulation of placental enzymes of the carbohydrate and lipid metabolic pathways. 3 55

1. Cataract formation in streptozotocin-induced diabetes in rats was reduced by approximately 85% when a diet rich in maize oil (300 g/kg diet) (fat diet) was given, thus confirming results of earlier studies. However, the concentration of sorbitol in the lens of diabetic animals remained high, the values for diabetic rats given the standard diet and the fat died being 65 and 40 mumol/g protein respectively. 2. With the standard diet, the fatty acid profile of the triglycerides of the epididymal fat pads was characterized by a greater relative proportion of saturated fatty acids for the diabetic animals compared to that for the normal animals. The fat diet moderated the tendency towards saturation in the diabetic animals. 3. The fat diet had other effects on the diabetic animals; these included a reduced mortality rate, increased body-weight, a decrease in the daily water intake, and in the daily urinary excretion of glucose and urea. 4. In the diabetic animals the fat diet had no effect on the specific activities in the liver of hexokinase (EC 2.7.1.1), glucokinase (EC 2.7.1.2), phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40). However, the specific activity of glucose-6-phosphatase (EC 3.1.3.9) was reduced, while that of malate dehydrogenase (decarboxylating) (NADP) (EC 1.1.1.40) was increased. The NAD+:NADH ratio, as calculated from liver pyruvate and lactate concentrations, tended to increase. 5. The results suggested that the fat diet moderated the long-term metabolic effects of diabetes.
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PMID:The effect of an unsaturated-fat diet on cataract formation in streptozotocin-induced diabetic rats. 13 11

Alloxan diabetes and injections of hydrocortisone into intact animals for 5-7 days resulted in a sharp decrease of NADP-dependent malate dehydrogenase in rat epididymal adipose tissue. Combined injection of insulin and hydrocortisone did not produce the decrease of the enzyme activity. Insulin injections into alloxan diabetic rats recovered the activity of NADP-malate dehydrogenase up to the control. Pyruvate kinase activity was decreased under diabetes, and insulin injections produced further decrease of the enzyme activity in diabetic rats. Activities of lactate dehydrogenase and NAD-dependent malate dehydrogenase were less decreased under diabetes. Comparison of lactate dehydrogenase isoenzymes spectrum in adipose tissue of normal and diabetic rats revealed a considerable increase of LDH-1 and a decrease of LDH-4 under diabetes. Insulin injections greatly normalized LDH isoenzyme spectrum.
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PMID:[Antagonism in the action of hydrocortisone and insulin in vivo on enzymes of pyruvate and malate metabolism in adipose tissue]. 97 79

Enzyme activities operative in glucose degradation and citrate cleavage pathway were studied in the adipose tissue of twenty-four patients with adult-onset diabetes and normal body weight, aged 59+/-9 years, and twenty-four matched controls. In normal tissue, type II (heat-inactivated) hexokinase moderately predominated over type I (heat-resistant). 6-Phosphofructokinase had an extremely low activity, which was by far the lowest among the ten glycolytic enzyme activities investigated, and which therefore might greatly limit the glycolytic rate. The level of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase (decarboxylating) was elevated above that occurring in other tissues. This, especially if considered together with the low 6-phosphofructokinase activity, would suggest a major role of pentose cycle in glucose degradation. Of the citrate cleavage pathway enzymes, ATP citrate-lyase, although having a lower activity than malate dehydrogenase and malate dehydrogenase (decarboxylating) (NADP), was readily measurable, which contrasts with previous data by others. This finding is consistent with the occurrence of lipogenetic capacity in human adipose tissue. In diabetic tissue, there was a decreased activity, both on a protein and on a wet-weight basis, of enzymes concerned with the glucose entry into metabolic pathways, namely hexokinase (both type I and, especially, type II) and pentose cycle dehydrogenases, as well as of pyruvate kinase. This could be connected with the defective glucose utilization by adipose tissue in diabetes. Beside the above-mentioned dehydrogenases, malate dehydrogenase (decarboxylating) (NADP) was also diminished. The reduction of these NADPH-forming enzymes, which supply reducing equivalents for fatty acid synthesis, would suggest a depressed lipogenesis.
Diabetes 1975 Oct
PMID:Enzymes of glucose metabolism and of the citrate cleavage pathway in adipose tissue of normal and diabetic subjects. 118 27

Experimental diabetes rats was induced in rats by intraperitoneal streptozotocin. The changes of glucose, sorbitol, fructose and free myoinositol in diabetic sciatic nerve and plasma, the changes of enzyme activity of sciatic nerve in relation to glucose, lipid and protein metabolism were studied during 1, 2, 4, 6, 12 weeks after induction of diabetes. The structural changes of 6 and 12 week diabetic sciatic nerve were observed sequentially by light and electron microscopy during the course of 6 and 12 weeks. The results showed that glucose, sorbitol and fructose in blood and sciatic nerve were increased markedly, but free myo-inositol was normal in blood and decreased in sciatic nerve. The enzyme activity such as ICDH, MDH, LDH, alpha-GPDH all reduced, but the activity of sorbitol dehydrogenase increased. Various ultrastructural changes such as swollen unmyelinated fibers, swollen mitochondria in axon, degenerative changes of myelin sheath and atrophic axon were observed, but no changes was found by light microscopy.
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PMID:[Pathogenesis of peripheral neuropathy in streptozotocin-induced diabetes in rats]. 252 88

Experimental diabetes was induced in wistar rats by intraperitoneal streptozotocin in a single dose of 60-65 mg per kg body weight. The changes of myocardium enzyme histochemistry and ultrastructure were observed during the 2nd, 4th, 6th, 12th week of diabetic state. The glucose metabolism enzyme activities such as ICDH, SDH, MDH, LDH, all decreased. The results indicated that glucose oxidation and glycolysis reduced. In the ventricular myocardium of diabetic rats, varying degrees of ultrastructural change were apparent. Swelling of mitochondria was observed. Focal areas showed myofibrillar degeneration, and cardiac muscle muscle cells showed condensation of nuclear chromatin. Lipid droplets could be seen in the cytoplasm of cardiac myocytes. The ultrastructural changes in the cardiac muscle cells were not accompanied by any changes in the endothelial cells and smooth muscle cells of the small vessels or capillaries. This study provides a strong evidence for the occurrence of a primary myocardial disease in the model of streptozotocin-induced diabetes. The primary cardiomyopathy was not dependent on vascular pathological changes.
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PMID:[Studies of enzyme histochemistry and ultrastructure of the myocardium in rats with streptozotocin-induced diabetes]. 252 54

Sand rats (Psammomys obesus) maintained on a diet providing a free choice between laboratory chow and salt bush (Atriplex halimus) were classified into four groups differing in extent of the diabetic syndrome: A, normoglycemic-normoinsulinemic; B, normoglycemic-hyperinsulinemic; C, hyperglycemic-hyperinsulinemic; or D, hyperglycemic with reduced insulin levels. The metabolic pattern of these groups was characterized by measuring the uptake of fatty acid-labeled, very-low-density lipoprotein-borne triglycerides (VLDL-TG) and [3H]-2-deoxyglucose (2-DOG) into muscle and adipose tissues; incorporation of [14C]alanine into glycogen in vivo; gluconeogenesis from lactate, pyruvate, and alanine in hepatocytes; the effect of insulin on glycogen synthesis from glucose; the oxidation of albumin-bound [1-14C]palmitate and [14C]glucose in strips of soleus muscle; activities of muscle and adipose tissue lipoprotein lipase; and activities of rate-limiting enzymes of glycolysis, gluconeogenesis, and fatty acid synthesis in liver. In group A, uptake of VLDL-TG and activity of lipoprotein lipase were higher in adipose tissue and lower in muscle than in albino rats. In the liver, gluconeogenesis and the activity of phosphoenolpyruvate carboxykinase, as well as lipid synthesis and the activity of NADP-malate dehydrogenase, were higher than in albino rats, whereas activity of pyruvate kinase was lower. In group B, uptake of VLDL-TG by adipose tissue and muscle and lipoprotein lipase activity were similar or higher than in group A. Uptake of 2-DOG by muscle and adipose tissue and activity of liver phosphoenolpyruvate carboxykinase were lower than in group A. In groups C and D, uptake of VLDL-TG and lipoprotein lipase activity in muscle were further increased.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1986 Jun
PMID:Characterization of stages in development of obesity-diabetes syndrome in sand rat (Psammomys obesus). 351 25

Regionally selective and time-dependent variations were observed in the activity of brain aspartate aminotransferase at early phases of diabetes. Malate dehydrogenase activity showed an opposite pattern of changes in soluble and particulate fractions of cerebral hemispheres and brain stem, with cerebellum showing consistent increase in the activity. The activity of both the enzymes increased significantly in liver, in contrast to heart where malate dehydrogenase activity decreased in particulate fraction. Insulin treatment to diabetic animals restored the enzymes to near control levels at early stages of diabetes, except in liver. The results indicate that malate-aspartate shuttle is probably stimulated under diabetic conditions to enable glycolysis to continue and ATP levels to be restored partially, particularly in cerebellum and liver.
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PMID:Malate-aspartate shuttle enzymes in rat brain regions, liver and heart during alloxan diabetes and insulin replacement. 391 Apr 26


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