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

The increased level of the glycosylated hemoglobin (hemoglobin A1c) in the diabetic patient has proved to be an interesting clue to understanding the biochemical basis of the sequelae of diabetes. This minor hemoglobin, which arises as nonenzymatic postsynthetic addition of glucose to hemoglobin A, acts as an indicator molecule for the glucose environment over a 3-5-wk period prior to measurement. Reasoning that a similar glycosylation reaction could be occurring with other body proteins, we have studied the ocular lens. The lens, like the erythrocyte, is not dependent on insulin for glucose concentration in the extracellular milieu that would be elevated in the diabetic state. These studies have revealed that a high glucose in vivo or an increased glucose or glucose-6-phosphate concentration in vitro leads to the glycosylation of epsilon-amino groups of lysine residues in bovine and rat lens crystallins. This glycosylation imparts an increased susceptibility of the crystallins to sulfhydryl oxidation. Disulfide crosslinks result in the formation of high molecular weight aggregates and an opalescence of the crystallin solutions.
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PMID:Role of nonenzymatic glycosylation in the development of the sequelae of diabetes mellitus. 12 96

Using [14-C]lysine protocollagen substrate prepared from chick embryo tibiae, lysyl hydroxylase activity was found in the 17 000 times g supernatant and particulate fractions obtained from homogenates of isolated rat renal glomeruli. Specific activities using the latter as an enzyme source were about 20-30% that of the supernatant. [14-C]Hydroxylysine formation was proportional to substrate and enzyme concentration, and to time for up to 120 min of incubation. Omission of alpha-ketoglutarate and ascorbate in the incubational assay markedly depressed activity. Hydroxylation of substrate by supernatant enzyme from streptozotocin diabetic rats was significantly increased over that of normal. In contrast, the activity of supernatant fractions from glomeruli of pancreatectomized, normoglycemic animals did not differ from that of non-operated controls. It is concluded that elevated glomerular lysine hydroxylase activity accompanies the increased glomerular collagen synthesis found in streptozotocin diabetes, and that chronic hyperglycemia may be implicated in these changes.
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PMID:Glomerular protocollagen lysyl-hydroxylase activity in streptozotocin diabetes. 12 80

To study the effect of streptozotocin induced diabetes on glomerular basement membrane (GBM) synthesis, an isolated rat glomerular preparation has been developed, and its metabolic properties have been defined. The chemical composition of normal rat GBM isolated from this preparation closely resembles human GBM. Incubation with [U-14C] lysine leads to prompt incorporation of label into GBM and the subsequent appearance of labeled hydroxylysine. A 1-h lag before detection of labeled hydroxylysine in GBM suggests a delay in the release of GBM precursors. Significantly lower counts appeared in the nondialyzable fraction of the medium than in insoluble GBM during pulse-chase experiments, and labeled hydroxylysine accounted for a lower portion of the total counts in the medium (0.85%) than in the GBM (1.98%). Isolated glomeruli were prepared from streptozotocin diabetic rats of 4-6 wks duration. After incubation with [ U-14C] lysine recovery of label in diabetic GBM (88.98+/-8.26 nmol/g GBM) did not differ from age matched controls (82.52 +/- 8.26 nmol/g GBM). In pulse-chase experiments recovery of label in hydroxylysine of diabetic GBM (o.473 +/- 0.082 nmol/g GBM) did not differ from age matched controls (0567+/-0.065 nmol/g GBM). These findings indicate normal rates of GBM synthesis and hydroxylation of lysine residues in animals with streptozotocin diabetes.
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PMID:Glomerular basement membrane: biosynthesis and chemical composition in the streptozotocin diabetic rat. 13 2

The effect of diabetes and insulin on the activities of both prolyl hydroxylase (trivial name; proline,2-oxoglutarate dioxygenase, EC 1.14.11.2) and lysyl hydroxylase (trivial name; lysine,2-oxoglutarate dioxygenase, EC 1.14.11.4) in isolated rat renal glomeruli was determined. Three groups of experimental animals were used: age-matched controls, streptozotocin-diabetic, and insulin-treated streptozotocin-diabetic. Using 14C-labeled lysine or proline hydroxylase substrate prepared from chick embryo tibiae, glomerular 17 000 X g supernatant enzyme was incubated in a complete hydroxylating system for 60 and 120 min Lysyl hydroxylase activity was significantly increased in diabetic preparations, but prolyl hydroxylase activity did not differ from control. Administration of insulin to streptozotocin-injected animals completely restored glomerular lysyl hydroxylase to normal levels. The results suggest that the specific elevation of lysyl hydroxylase relates to the biochemical changes contributory to diabetic nephropathy, and that insulin may reverse this process.
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PMID:Effect of diabetes and insulin on rat renal glomerular protocollagen hydroxylase activities. 18 35

The components of the hemoglobin-A1 fraction--hemoglobins A1a--c--arise from nonenzymatic glycosylation of hemoglobin A at the beta-chain N-terminal amino groups and can be resolved from hemoglobin A by cation exchange chromatography. Glycosylation can also occur at the alpha-chain N-terminals as well as the epsilon-amino groups of lysine residues of both alpha- and beta-chains; this results in glycosylated species appearing in the hemoglobin-A fraction. In this study, we determined the extent of hemoglobin-A glycosylation using a colorimetric chemical method specific for the detection of ketoamine-linked hexoses in proteins. We demonstrate increased glycosylation of the main hemoglobin-A fraction in diabetic patients, which correlates significantly (r = 0.72, P less than 0.001) with the hemoglobin-A1 percentage determined by column chromatography in the corresponding hemolysates. This finding provides the basis for the application of this chemical procedure to the measurement of total glycosylation of hemoglobin.
Diabetes 1979 Apr
PMID:Glycosylated hemoglobins: increased glycosylation of hemoglobin A in diabetic patients. 43 73

Prostaglandin E (PGE) infusion in normal man inhibits the acute insulin response to glucose. In order to determine whether endogenously released PGE might also inhibit insulin secretion, glucose-stimulated insulin responses were investigated in normal volunteers after furosemide (40 mg i.v.), a stimulator of endogenous PGE synthesis. Acute insulin response to glucose (20 g i.v.) was significantly reduced by furosemide (response before furosemide: 36 +/- 5 muU/ml; after furosemide: 26 +/- 5 muU/ml, m +/- SE, mean change 3--10 min, N = 8, P less than 0.01), whereas glucose disappearance rates were not modified after furosemide. Infusion of lysine acetylsalicylate (LAS), an inhibitor of endogenous PGE synthesis, completely reversed the inhibitory effect of furosemide on insulin secretion and also augmented acute insulin response to glucose (response before furosemide + LAS: 41 +/- 6 muU/ml; during furosemide + LAS: 50 +/- 7 muU/ml, N = 10, P less than 0.02). This effect was associated with an increase in glucose disappearance rates (P less than 0.05). These findings demonstrate that (1) furosemide inhibits glucose-induced acute insulin responses and (2) LAS completely reverses the inhibitory effect of furosemide and also accelerates glucose disposal. It is suggested that furosemide acts via the release of endogenous PGEs, which are known to inhibit insulin responses in man.
Diabetes 1979 Sep
PMID:Acetylsalicyclic acid restores acute insulin response reduced by furosemide in man. 46 10

In incubation experiments with isolated glomeruli, an increased synthesis of protein and basement membranes was detected in streptozotocin-diabetic rats compared to metabolically healthy controls. Chemical analysis of isolated basement membranes and incorporation studies did not give any indication of enhanced hydroxylation of lysine in the diabetic membrane. Different glucose concentration in the incubation medium and insulin in vitro did not influence protein and basement membrane synthesis of non-diabetic glomeruli. On the other hand, in diabetic glomeruli the synthetic activity depends on glucose concentration. Insulin had a stimulatory effect on protein and basement membrane synthesis diminished at lower glucose concentration and did not inhibit the increased synthetic activity demonstrated at higher glucose concentration. Therefore, these results may be attributable to an energy deficit of incubated glomeruli and not to a lower glucose stimulation of synthesis. By treatment of diabetic rats with insulin in vivo the synthetic activity was not affected by brief normalization of blood sugar. Insulin treatment from the beginning of diabetes only lead to a normalization of protein synthesis in moderate metabolic control. On the other hand, a rise of basement membrane synthesis could only be prevented by strict metabolic control of the rats. These results show that basement membrane synthesis reacts more sensitively to the diabetic situation than overall protein synthesis. Insulin deficiency does not appear to be one of the factors directly influencing basement membrane synthesis.
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PMID:[Pathogenesis of diabetic microangiopathy. Protein and basement membrane synthesis in isolated kidney glomeruli of diabetic and non-diabetic rats]. 51 Oct 78

1. Between 1971 to 1977, 74,521 urines, collected on filter paper and mailed in, were screened by the Metabolic Screening Program of the Children's Hospital. These represented 45.9% of live births in B.C. hospitals were the program has been available. The mean age of the infants was 4.4 weeks. Urines were examined by chromatography with ethyl acetate-pyridine-water for sugars. 1423 (2.13%) had an abnormal pattern necessitating a repeat urine card. A persistent abnormality was noted in 167 (0.22%) and from these a liquid urine sample was obtained for two dimensional amino acid chromatography and/or a repeat sugar chromatography. 2. In 47 (0.06%) of these a definite metabolic abnormality was confirmed. These included cases of Iminoglycinuria (8), Hartnup trait (4), Nonketotic hyperglycinemia (2), Histidinemia (1), Cystathioninuria (5), Argininosuccinic aciduria (1), Maple Syrup Urine Disease (1), Diabetes Mellitus (1), Renal glycosuria (1) and Persistent galactosuria (3). 201 infants had a slight increase of cystine and/or lysine, and 19 of these were documented to be heterozygous for cystinuria.
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PMID:Review of Metabolic Screening Program of Children's Hospital, Vancouver, British Columbia. 1971--1977. 51 48

Twenty children with diabetes inspidus, 19 children and adolescents and one baby of 2 months, were treated with DDAVP. The drug was very effective, the average urine volume being 1.7 L/24 hours. The control of the diuresis in the baby was very satisfactory. There were no secondary effects and the only episode of water intoxication occurred in a girl with corticosteroid deficiency which was not well controlled. The effects of this drug are discussed in the light of the biochemistry and pharmacology and the activity compared with that of Lysine vasopressin (LVP). Plasma levels of DDAVP and LVP showed that DDAVP persists for longer which may explain its greater potency and duration of action.
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PMID:[Treatment of ADP responsive diabetes insipidus in children with DDAVP (1-desamino-8-D-arginine-vasopressin)]. 61 Jun 62

The content of the following 10 amino acids was investigated by means of a microbiological method (with the use of auxotrophic E. coli mutants) in 23 patients with diabetes mellitus with fatty infiltration of the liver and in 27 patients without it: histidine, proline, methionine, cystine, tryptophane, leucine, arginine, tyrosine, lysine, and phenylalanine. Results of study of the amino acid balance were compared with the morphological changes in the liver (the material was obtained by biopsy). All the diabetic patients displayed an increase in the proline, tryptophane, tyrosine, leucine, and cystine content, and a reduction of phenylalanine and lysine level. Fatty hepatocyte infiltration was also accompanied by a significant elevation of methionine and a reduction of arginine content. A tendency to normalization of leucine and lysine only was seen after the treatment of diabetic patients with fatty hepatocyte infiltration; diabetic patients without any fatty infiltration showed normalization in the tyrosine, lysine content and a tendency to the normalization of the cystine, tryptophane level, but no change in the methionine content.
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PMID:[Characteristics of the amino acid spectrum of blood serum in diabetes mellitus]. 88 34


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