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

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

The activity of enzymes regulating the processes providing functional activity of leukocytes was studied in the exudate leukocytes of healthy rabbits and animals with alloxan diabetes. Rabbits with diabetes displayed a reduction of hexokinase, phosphoglucomutase, glucose-6-phosphate dehydrogenase and adenylate kinase activity. The activity of UDPH-pyrophosphorylase, UDPH-glycogentranspherase, 6-phosphogluconate dehydrogenase and glutathion reductase showed no significant changes in the exudate leukocytes in diabetes. A reduction of hexokinase and glucose-6-phosphate dehydrogenase limiting glycolysis and the pentose-phosphate cycle, respectively, providing energy for leukocytes and important in protein metabolism of these cells, is of great significance in the reduction of functional activity of leukocytes in the inflammatory focus in diabetes.
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PMID:[Enzymatic profile of the exudate leukocytes in diabetes mellitus]. 9 55

Acitivites of the hepatic enzymes were determined in spontaneous diabetes rats. The activities of the enzymes were compared with those in normal rats and in streptozotocin diabetic rats. In the spontaneous diabetes rats, glycogen phosphorylase and glycogen synthase were 14.6 +/- 0.6 and 1.73 +/- 0.15 U respectively. The activities of both the enzymes were significantly increased. In the spontaneous diabetes rats glucokinase was 3.82 +/- 0.5 U showing a significant increase. On the contrary, the activity of the enzyme was decreased in the streptozotocin diabetic rats. Glucose-6-phosphatase was increased both in the spontaneous diabetes rats and in the streptozotocin diabetic rats. Fructose-1,6-diphosphatase was increased in the spontaneous diabetes rats. Glucose-6-phosphate dehydrogenase was increased in the spontaneous diabetes rats and decreased in the streptozotocin diabetic rats. In the spontaneous diabetes rats phosphofructokinase showed a reduction of the activity and glucose-6-phosphate dehydrogenase was elevated. These findings are consistent with the results of activities of the hepatic enzymes in adult-onset diabetic patients. These patterns of the hepatic enzymes in the spontaneous diabetes rats were different from those in the streptozotocin diabetic rats. From these patterns of activities of the hepatic enzymes, the spontaneous diabetes rats produced by repetition of selective breeding according to Goto et al. (1975,1976) are an excellent model of human adult-onset diabetes.
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PMID:Activities of hepatic enzymes in spontaneous diabetes rats produced by selective breeding of normal Wistar rats. 15 47

In leukocytes of exudate from diabetic rabbits, the activities of hexokinase, phosphoglucomutase and glucose-6-phosphate dehydrogenase are increased, and a tendency of adenylate kinase activity to decline is observable. The activities of UDP-pyrophosphatase, UDP-glycogentransferase, 6-phosphogluconate dehydrogenase and glutahione reductase in the exudate erythrocytes in diabetes are not essentially altered. The decrease of the key enzymes of glycolysis and pentose phosphate cycle, providing the leukocytes with energy and metabolites, reduces the functional activity of leukocytes from exudate in diabetes.
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PMID:[Enzyme profile of exudate leukocytes from diabetic rabbits]. 51 96

The variation of the activities of glutathion peroxidase, glutathion reductase, glucose-6-phosphate dehydrogenase, as well as of the concentrations of lipid peroxides and -SH groups of nonproteic nature, was followed up in the hepatocyte of normal rats, of those with, streptozotocin-induced-diabetes, and of diabetic rats treated with thiazolidin carboxylic (ThCA) acid. Free peroxides and glutathion peroxidase were increased in the diabetic animals as against the normals, whereas glutathion reductase, glucose-6-phosphate dehydrogenase and the -SH groups of nonproteic nature had lower values. A return to normal of these parameters was noticed in the animals treated with ThCA.
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PMID:The effect of thiazolidin carboxylic acid (ThCA) on the redox equilibrium maintaining in the rat hepatocyte with streptozotocin-induced diabetes. 63 31

Activity of dehydrogenases related to pentosephosphate pathway was not distinctly altered in soluble fraction of kidney cortex and medulla after 48 and 72 hrs of starvation. In diabetes the activity of these enzymes in rat kidney, as distinct from liver tissue, was not decreased but it was elevated and within 72 hrs after administration of alloxan the activity of glucose-6-phosphate dehydrogenase was increased 2-fold and the activity of 6-phosphogluconate dehydrogenase was increased by 30% above the normal level. Content of free fatty acids was also increased in kidney cortex of diabetic rats within 72 hrs after administration of alloxan. Alterations in content of free fatty acids were not observed either in kidney of diabetic animals within other studied periods (6 and 14-16 days) of treatment or in the tissue of starved rats. The data obtained suggest that free fatty acids do not participate immediately in controlling effect on dehydrogenases of pentosephosphate pathway in kidney in vivo.
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PMID:[Effect of starvation and diabetes on the activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases and on the free fatty acid content of rat kidney cortex and medulla]. 66 69

In human erythrocytes activities of glucose-6-phosphate and lactate dehydrogenases were decreased approximately 2-fold in moderately severe and critical forms of diabetes mellitus, as compared with normal state. The lactate dehydrogenase activity was more distinctly decreased than the glucose-6-phosphate dehydrogenase activity. General medical treatment increased the activity of the enzymes (which catalyzed the ATP formation in erythrocytes) and normalized their relation.
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PMID:[Lactate dehydrogenase and glucose-6-phosphate dehydrogenase activity in the erythrocytes in diabetes mellitus]. 102 30

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

In a supernatant of rat kidney cortex homogenate activities of glucose-6-phosphate and 6-phosphogluconate dehydrogenases were shown to be approximately equal. These enzymes were found in kidney medulla; their activities, similar to those glycolytic enzymes, were higher in kidney medulla than in cortex. In diabetes the activity of glucose-6-phosphate dehydrogenase from kidney cortex was increased.
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PMID:[Dehydrogenases of the pentose-phosphate pathway of the kidney cortex and medulla in normal and alloxan diabetic rats]. 121 74

The effects of unilateral nephrectomy (UN) and streptozotocin (STZ) diabetes on the activities of enzymes involved in uridine and cytidine synthesis in early renal growth (3-14 days after stimulus to growth) have been compared. Measurements were also made of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) and of glucose 6-phosphate (G6P), UDP-glucose, and glycogen, in relation to phosphoribosyl pyrophosphate, ribonucleotide, and complex carbohydrate formation. There were striking differences in the activities of CTP synthetase, G6PDH, and 6PGDH in the two conditions, with a three-fold increase in all three enzymes at 3 and 5 days and a two-fold increase above basal values at 14 days of STZ diabetes. The UN group showed no significant change in CTP synthetase at any stage and the activity of G6PDH and 6PGDH only kept pace with renal growth. Changes in routes of uridine synthesis were less marked, with a more rapid rise in carbamoyl-phosphate synthetase (glutamine) and a lesser response of dihydroorotate dehydrogenase in the UN relative to the STZ-diabetic groups. The enzymes of complex II and of uracil phosphoribosyltransferase showed essentially similar patterns during renal hypertrophy in UN and STZ diabetes. The parallel increase in CTP synthetase, G6PDH, and 6PGDH in the kidney in diabetes, also known to increase in growth situations in hepatomas and in renal tumors, is discussed in relation to hormone signals involved in renal growth. The importance of the concentration of CTP, and thus of CTP synthetase, in the CTP-cytidyltransferase reaction, an enzyme with a high Km for CTP, makes the present observation of the striking increase in CTP synthetase in STZ diabetes of particular interest in relation to phosphatidylcholine formation and hormone signal transduction.
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PMID:Uridine and cytidine nucleotide synthesis in renal hypertrophy: biochemical differences in response to the growth stimulus of diabetes and unilateral nephrectomy. 138 Dec


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