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

In diabetes mellitus, the kidney and the gut--but not the liver or the muscle--undergo hypertrophy. Hypertrophy may be due to an increase in the rate of protein synthesis and/or to a decrease in proteolysis. In order to resolve this issue we assessed in vivo the rates of protein degradation by measuring the disappearance rates of 3H- and 14C-labelled valine incorporated into renal and liver proteins of control and streptozotocin-diabetic mice. The half-life of labelled valine, which is inversely related to the rate of protein degradation, was shorter and of similar magnitude both in the kidneys and livers of diabetic (70 +/- 6 h) than of control (96 +/- 8 h) animals. Yet, only the kidneys of diabetic animals underwent hypertrophy (0.33 +/- 0.01 vs. 0.29 +/- 0.01 g, P < 0.05; 2.22 +/- 0.10 vs. 1.64 +/- 0.05% of body weight, P < 0.01)). The increase in protein degradation rate affected all subcellular (mitochondrial, nuclear, microsomal and cytosolic) fractions of the kidney but not the mitochondria of liver. We surmise that an increase in the degradation of proteins is a widely generalized phenomenon in diabetes mellitus. For reasons that are still unclear, but that may relate to the hyperglycaemia, in the kidneys of diabetic animals this process is associated with a transiently larger increase in protein synthesis resulting in hypertrophy, whereas in liver, changes in protein degradation proceed 'pan passu' with those in protein synthesis resulting in the preservation of organ weight. Accelerated renal protein turnover and hypertrophy are early manifestations and perhaps harbingers of more severe renal changes in diabetes mellitus.
Diabetes Res Clin Pract 1997 Jan
PMID:Renal protein degradation in streptozotocin diabetic mice. 906 65

Experimental streptozotocin-induced diabetes resulted in important changes in body weight which were associated with abnormalities in water and food intake. In addition, diabetic rats showed a clear muscle atrophy involving a decrease in both skeletal muscle size and protein content. This was accompanied by a marked loss of total carcass nitrogen. These changes were related to important alterations in protein turnover in skeletal muscle. Thus, the diabetic animals showed changes in the fractional protein rates of both synthesis (decreased by 37%) and degradation (increased by 140%). The increased protein degradation observed in the muscle of the diabetic animals was associated with important changes in the concentration of both circulating and muscle amino acids. Interestingly, the diabetic animals did not show important changes in either liver or kidney protein turnover rates, in spite of having a clear increase (over 50%) in kidney mass. In addition, and although the total amino acid concentration was not affected by the diabetic state, the chemically induced diabetic animals showed important elevations of branched-chain amino acids (leucine, isoleucine, and valine) in both blood and skeletal muscle. Similarly, important decreases in the blood concentrations of glutamate+glutamine, alanine, glycine, proline, serine, and threonine were also observed. These observations reinforce the idea of the association between muscle protein wasting, increased protein turnover, and alterations in branched-chain amino acids previously proposed by our group.
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PMID:The increased skeletal muscle protein turnover of the streptozotocin diabetic rat is associated with high concentrations of branched-chain amino acids. 923 2

Disruption of the melanocortin-4 (MC-4) receptor gene in mice results in maturity-onset obesity, hyperinsulinaemia and hyperglycaemia. These phenotypes are characteristic of human obesity that frequently accompanies non-insulin-dependent diabetes. It is therefore possible that human MC-4 receptor gene mutations contribute to human obesity. To test this possibility, we examined by DNA sequencing the entire coding region of the human MC-4 receptor gene in 40 morbidly obese (BMI > 35 kg/m2) white British males and examined the 5'- and 3'-flanking regions in 20 out of these obese subjects. We also sequenced all these regions in 10 lean (BMI < 18 kg/m2) white British males for a reference. We identified a single nucleotide substitution that replaces valine with isoleucine at codon 103, in two obese subjects in the heterozygous state. No other nucleotide alterations were found. The prevalence of this missense variant was studied in 322 white British males (190 with BMI > 28 kg/m2 and 132 with BMI < 22 kg/m2) selected from a population-based epidemiological survey. In these subjects, no homozygotes for the isoleucine allele were found. The frequency of heterozygotes was similar (4.2 vs 4.5%) in the two groups and there was no significant difference in BMI, total skinfold thickness, plasma insulin and glucose levels between heterozygotes and codon-103 valine homozygotes in either group. These results suggest that coding sequence mutations in the MC-4 receptor gene are unlikely to be a major cause of human obesity, at least in white British males.
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PMID:Molecular screening of the human melanocortin-4 receptor gene: identification of a missense variant showing no association with obesity, plasma glucose, or insulin. 926 95

We have previously found that carbamylated hemoglobin (carHb) levels are increased in chronic renal failure and correlate positively with blood urea nitrogen (BUN) levels and with the duration of exposure to urea. In a fashion analogous to glycosylated hemoglobin in diabetic patients, it is possible that carHb may better reflect BUN levels before hemodialysis (preBUN) and also between hemodialysis sessions. We therefore tested the hypothesis that carHb could be a better index of adequacy of hemodialysis than the urea reduction ratio (URR). Fifty hemodialysis patients had carHb measured every 2 months for 14 months; the carHb level was compared with URR and preBUN levels, as assessed by changes in absolute numbers and trends of the BUN levels between hemodialyses. Mean URR was above 61% throughout the 14 months. Mean carHb levels did not change significantly during the study and were only weakly correlated with URR. However, there was a much better correlation between predialysis BUN and carHb, suggesting that carHb levels reflect more accurately the changes in BUN between hemodialysis sessions. To further test this hypothesis, we subdivided the patients arbitrarily, depending on the change in preBUN between two consecutive carHb measurements. We found significantly lower carHb levels when BUN decreased or remained stable than when it increased or was persistently high. In patients with decreasing or stable BUN, carHb was significantly lower than in patients with persistently high or increasing BUN (carHb 81.5 +/- 3.6 microg valine hydantoin [VH]/g Hb v 123.7 +/- 11.7 microg VH/g Hb, respectively; P < 0.001). URR was not different between groups. In addition to changes in BUN levels, carHb was correlated by multiple regression analysis with the presence of diabetes, weight, and plasma HCO3. The relationship between diabetic patients and carHb levels was complex because such patients tend to have higher preBUN levels, higher protein catabolic rate, and lower HCO3 levels. These results demonstrate that carHb reflects the changes between dialysis BUN and may serve as a more accurate index of uremia control. Clinically, it appears that well-dialyzed patients have carHb levels lower than 100 microg VH/g Hb.
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PMID:Carbamylated hemoglobin in hemodialysis patients. 929 64

A population-based study in the Netherlands has recently demonstrated that a mutation of the human insulin receptor (HIR-973 valine to methionine) is associated with hyperglycaemia and an increased prevalence of non-insulin-dependent diabetes mellitus (NIDDM). The aim of the present study was to assess whether this mutation leads to a functional alteration of the insulin receptor. We prepared the HIR-973 mutant by in vitro mutagenesis. This mutant was transiently overexpressed in HEK 293 cells either alone or together with insulin-receptor substrate-1 (IRS-1) or Shc. Insulin stimulated autophosphorylation, phosphorylation of the substrates IRS-1 and Shc as well as activation of phosphatidylinositol-3 (PI3)-kinase were studied. Autophosphorylation of HIR-973 and its susceptibility to hyperglycaemia induced inhibition was not different from HIR-wt. Human insulin receptor with a juxtamembrane deletion HIR-deltaJM which is known to impair HIR/IRS-1 interaction was used as control. While the HIR-deltaJM induces a reduced IRS-1 phosphorylation HIR-973 showed even a slightly increased ability to phosphorylate IRS-1 (n = 7, 115% of control, p < 0.01). Shc phosphorylation was only mediated by HIR-wt and HIR-973 but not by HIR-deltaJM. Again a tendency to higher phosphorylation of Shc was seen with HIR-973 (n = 7, 109% of control, NS). When PI3-kinase activity was measured in IRS-1 precipitates similar activity was found for HIR-wt and HIR-973 whereas PI3-kinase stimulation was reduced with HIR-deltaJM. In summary, the data suggest that HIR-973 does not impair the first steps of the insulin signalling cascade. It is therefore unlikely that this mutation may cause cellular insulin resistance. The close vicinity of this mutation to insulin receptor domains which are involved in IRS-1 and Shc binding may, however, alter the interaction of the insulin receptor with these substrates. This could explain the slightly increased insulin effect on tyrosine phosphorylation of these docking proteins. These characteristics of HIR-973 might have a compensatory function of impaired signal transduction further downstream of the signalling chain in this specific subgroup of NIDDM patients.
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PMID:A 973 valine to methionine mutation of the human insulin receptor: interaction with insulin-receptor substrate-1 and Shc in HEK 293 cells. 934 93

Non-insulin-dependent diabetes mellitus (NIDDM) is a heterogeneous disorder characterized by hyperglycemia resulting from defects in insulin secretion and action. Recent studies have found mutations in the hepatocyte nuclear factor-4 alpha gene (HNF-4alpha) in families with maturity-onset diabetes of the young (MODY), an autosomal dominant form of diabetes characterized by early age at onset and a defect in glucose-stimulated insulin secretion. During the course of our search for susceptibility genes contributing to the more common late-onset NIDDM forms, we observed nominal evidence for linkage between NIDDM and markers in the region of the HNF-4alpha/MODY1 locus in a subset of French families with NIDDM diagnosed before 45 yr of age. Thus, we screened these families for mutations in the HNF-4alpha gene. We found a missense mutation, resulting in a valine-to-isoleucine substitution at codon 393 in a single family. This mutation cosegregated with diabetes and impaired insulin secretion, and was not present in 119 control subjects. Expression studies showed that this conservative substitution is associated with a marked reduction of transactivation activity, a result consistent with this mutation contributing to the insulin secretory defect observed in this family.
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PMID:A missense mutation in hepatocyte nuclear factor-4 alpha, resulting in a reduced transactivation activity, in human late-onset non-insulin-dependent diabetes mellitus. 944 83

Signs of protein-energy malnutrition are common in maintenance hemodialysis (HD) patients and are associated with increased morbidity and mortality. To evaluate the nutritional status and relationship between various parameters used for assessing malnutrition, we performed a cross-sectional study in 128 unselected patients treated with hemodialysis (HD) thrice weekly for at least two weeks. Global nutritional status was evaluated by the subjective global nutritional assessment (SGNA). Body weight, skinfold thicknesses converted into % body fat mass (BFM), mid-arm muscle circumference, hand-grip strength and several laboratory values, including serum albumin (SA1b), plasma insulin-like growth factor I (p-IGF-I), serum C-reactive protein (SCRP) and plasma free amino acids, were recorded. Dose of dialysis and protein equivalence of nitrogen appearance (nPNA) were evaluated by urea kinetic modeling. The patients were subdivided into three groups based on SGNA: group I, normal nutritional status (36%); group II, mild malnutrition (51%); and group III, moderate or (in 2 cases) severe malnutrition (13%). Clinical factors associated with malnutrition were: high age, presence of cardiovascular disease and diabetes mellitus. nPNA and Kt/V(urea) were similar in the three groups. However, when normalized to desirable body wt, both were lower in groups II and III than in group I. Anthropometric factors associated with malnutrition were low body wt, skinfold thickness, mid-arm muscle circumference (MAMC), and handgrip strength. Biochemical factors associated with malnutrition were low serum levels of albumin and creatinine and low plasma levels of insulin-like growth factor 1 (IGF-1) and branched-chain amino acids (isoleucine, leucine and valine). The serum albumin (SAlb) level was not only a predictor of nutritional status, but was independently influenced by age, sex and SCRP. Plasma IGF-1 levels also reflected the presence and severity of malnutrition and appeared to be more closely associated than SAlb with anthropometric and biochemical indices of somatic protein mass. Elevated SCRP (> 20 mg/liter), which mainly reflected the presence of infection/inflammation and was associated with hypoalbuminemia, was more common in malnourished patients than in patients with normal nutritional status, and also more common in elderly than in younger patients. Plasma amino acid levels, with the possible exception of the branched-chain amino acids (isoleucine, leucine, valine), seem to be poor predictors of nutritional status in hemodialysis patients.
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PMID:Factors predicting malnutrition in hemodialysis patients: a cross-sectional study. 973 31

The molecular mechanism by which some, but not all, variants of encephalomyocarditis (EMC) virus selectively infect pancreatic beta-cells in mice and induce IDDM has been an enigma for more than a decade. We report here that the binding site of the EMC viral capsid protein VP1 determines viral diabetogenicity. Recombinant chimeric EMC viruses containing threonine, serine, proline, aspartic acid, or valine at position 152 of the major capsid protein VP1 bind poorly to beta-cells. In contrast, recombinant chimeric EMC viruses containing alanine or glycine at position 152 of the VP1 bind efficiently to and infect beta-cells, resulting in the development of diabetes. Three-dimensional molecular modeling reveals that the van der Waals interactions are greater and the residues surrounding position 152 of the VP1 are more closely packed in recombinant chimeric viruses containing threonine, serine, proline, aspartic acid, or valine at position 152 than in recombinant chimeric viruses containing alanine or glycine at the same position. Our studies reveal that the surface areas surrounding alanine or glycine at position 152 of the VP1 are more accessible, thus increasing the availability of the binding sites for attachment to beta-cell receptors and resulting in viral infection and the development of diabetes.
Diabetes 1998 Apr
PMID:Determination of encephalomyocarditis viral diabetogenicity by a putative binding site of the viral capsid protein. 956 90

Glucagon-like peptide 1 (GLP-1) has been proposed as a new therapeutic agent in the management of diabetes because of its glucose-dependent stimulation of insulin secretion, but this is limited by its rapid degradation in vivo by dipeptidyl peptidase IV (DPP IV). In nonfasted anesthetized pigs, valine-pyrrolidide (a stable and selective inhibitor of DPP IV), at a dose that reduced plasma DPP IV activity by more than 90%, increased both the amount of intact GLP-1 in the basal state (from 5 +/- 1 to 18 +/- 7 pmol/l; P < 0.05) and the proportion remaining undegraded during an infusion (from 21.0 +/- 1.3 to 102.3 +/- 4.5%; P < 0.0001). This was associated with a prolonged plasma half-life for the intact peptide (from 1.0 +/- 0.1 to 3.2 +/- 0.2 min; P < 0.0005). In the basal (nonfasted) state, valine-pyrrolidide potentiated the effect of intravenous GLP-1 on the incremental area under the curve (AUC) for glucose (-0.50 +/- 0.91 to -2.83 +/- 0.59 20 min x mmol x l(-1); P < 0.05) and insulin (23.8 +/- 30.5 to 332.5 +/- 99.6 20 min x pmol x l(-1); P < 0.05). When an intravenous glucose load was given during the GLP-1 infusion, valine-pyrrolidide augmented the insulin response (AUC, 2,086.2 +/- 600.9 to 6,247.0 +/- 1443.9 40 min x pmol x l(-1); P < 0.05). These results suggest that by reducing GLP-1 degradation, DPP IV inhibition potentiates the insulinotropic effect of GLP-1 and may, therefore, be a viable approach to the management of diabetes.
Diabetes 1998 May
PMID:Dipeptidyl peptidase IV inhibition potentiates the insulinotropic effect of glucagon-like peptide 1 in the anesthetized pig. 958 48

Irreversible glycation of the hemoglobin A0 (HbA0) beta chain leads to the production of HbA1C, which can be used to monitor long-term blood glucose control in patients with diabetes mellitus. HbA1C is less positively charged than nonglycated HbA0, and this decrease in charge is the basis of ion-exchange and electrophoretic methods that measure HbA1C. We recently identified a sample that appeared to contain 46% HbA1C by an automated ion-exchange HPLC method (Bio-Rad Variant) but only 3.8% by an immunoinhibition latex agglutination method. A combination of traditional and mass spectrometric protein analysis and genomic DNA analysis of the Hb beta chain and genes revealed that the patient was heterozygotic for Hb-Raleigh, a variant containing a valine-->alanine substitution at position 1 of the beta chain. The amino-terminal alanine in this variant Hb is posttranslationally modified by acetylation, leading to a charge difference similar to glycation and making the behavior of HbA1C and Hb Raleigh virtually identical in the ion-exchange HPLC method. This observation suggests that it is important to confirm HbA1C values in excess of 15%, especially if they are not consistent with the clinical picture, by an independent HbA1C method such as immunoassay or boronic acid affinity chromatography. However, for this particular variant Hb, even these latter methods might be misleading, because the acetylated N-terminal amino acid of the Hb-Raleigh beta chain cannot be glycated.
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PMID:Hemoglobin Raleigh as the cause of a falsely increased hemoglobin A1C in an automated ion-exchange HPLC method. 962 56


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