bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucocorticoid-Induced Insulin Resistance: Dexamethasone Inhibits the Activation of Glucose Transport in Rat Skeletal Muscle by Both Insulin- and Non-Insulin-Related Stimuli
Authors: Weinstein Steven P , Paquin Tania , Pritsker Alla , Haber Richard S
Published: September 2013

To test the hypothesis that glucocorticoids inhibit muscle glucose transport apart from changes in early insulin-signaling events, we determined the effect of glucocorticoid treatment on the activation of glucose transport by both insulin and non-insulin-related stimuli (insulin-like growth factor [IGF] I and hypoxia) in rat skeletal muscle. Male Sprague-Dawley rats were treated with dexamethasone (Dex) (0.8 mg/kg for 2 days) and compared with pair-fed controls. 2-[3H]deoxyglucose (2-[3H]DG) uptake in isolated soleus muscles was measured under conditions in which uptake reflects glucose transport activity. In control muscles, 2-[3H]DG uptake was stimulated 10-fold by insulin (10 nmol/l) or IGF-I (50 nmol/l) and sixfold by hypoxia. Dex treatment decreased 2-[3H]DG uptake at all concentrations of insulin tested, reducing maximal insulin-stimulated 2-[3H]DG uptake by 41 ± 11% (mean ± SE, P < 0.05) and basal 2-[3H]DG uptake by 38 ± 6% (P < 0.01). Dex treatment also inhibited 2-[3H]DG uptake at all concentrations of IGF-I tested, reducing maximal IGF-I-stimulated 2-[3H]DG uptake by 29 ± 2% (P < 0.01), and decreased hypoxia-stimulated 2-[3H]DG uptake by 61% (P < 0.01). Dex treatment increased soleus GLUT4 protein content by 11%. Thus, Dex treatment reduces basal glucose transport and decreases the maximal response of skeletal muscle glucose transport to insulin, the related hormone IGF-I, and the non-insulin-related stimulus hypoxia. These findings support the hypothesis that, in addition to altering early insulin-signaling events, glucocorticoids may also act by inhibiting the glucose transport system, per se, perhaps by affecting GLUT4 subcellular trafficking.
Gi2 and Gi3 Proteins Mediate the Inhibition of Adenylyl Cyclase by Galanin in the RINm5F Cell
Authors: McDermott Alison M , Sharp Geoffrey W G
Published: September 2013

Inhibition of adenylyl cyclase activity is one of at least four mechanisms by which the neuropeptide galanin inhibits insulin secretion from pancreatic β-cells. In a membrane preparation of the insulin-secreting cell line RINm5F, a maximally effective concentration of galanin inhibited forskolin-stimulated adenylyl cyclase activity by 30%. Pretreatment of the cells with pertussis toxin abolished the inhibitory effect of galanin, indicating the involvement of Gi or Go guanine nucleotide binding proteins (G-proteins). Because galanin receptors interact with four G-proteins (Gi1, Gi2, Gi3, and Go1), any or all of these may inhibit adenylyl cyclase. Therefore, to identify the G-protein(s) involved, antibodies raised against various G-protein alpha-subunits were used to block the inhibition of forskolin-stimulated adenylyl cyclase activity by galanin in RINm5F membrane preparations. Antisera AS/7 and EC/2, specific for Gɑi1/ɑi2 and Gɑi3, respectively, were able to significantly attenuate the inhibitory effect of galanin, whereas antisera specific for Go proteins were not. The use of additional antisera specific for the various subtypes of Gi proteins indicated that Gi2 and Gi3, but not Gi1, are involved. Simultaneous application of antisera AS/7 and EC/2 resulted in a greater attenuation of the effect of galanin than application of either antiserum alone. Thus, galanin inhibition of adenylyl cyclase activity in these cells is selectively mediated by two inhibitory G-proteins, Gi2 and Gi3.
Effect of Treatment With a Hydroxymethylglutaryl Coenzyme A Reductase Inhibitor on Fasting and Postprandial Plasma Lipoproteins and Cholesteryl Ester Transfer Activity in Patients with NIDDM
Authors: Bhatnagar Deepak , Durrington Paul N , Kumar Sudesh , Mackness Michael I , Dean John , Boulton Andrew J M
Published: September 2013

Patients with non-insulin-dependent diabetes mellitus (NIDDM) have a greater risk of developing coronary heart disease than would be expected from a similar degree of hyperlipidemia in nondiabetic populations. Accelerated transfer of cholesteryl esters (CET) from high-density lipoprotein (HDL) to low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL), a process that is associated with atherosclerosis, may be a possible explanation for this. CET, plasma lipoprotein concentration, and mass in the fasting and postprandial state have been examined in 31 hyperlipidemic patients with NIDDM before and after 8 weeks of treatment with the hydroxymethylglutaryl (HMG)–coenzyme A (CoA) reductase inhibitor pravastatin in a double-blind, placebo-controlled, parallel group study. Body mass index, glycemic control, and blood pressure remained unaltered during the study period. Compared with placebo, pravastatin decreased fasting serum cholesterol (P < 0.001) and LDL cholesterol (P < 0.002) levels. The high basal CET (34.4 ± 13.1 nmol.ml−1 · h−1) was decreased significantly by pravastatin treatment (27.5 ± 13.7 nmol.ml−1 · h−1, P = 0.013). There was a fall in the total cholesterol, free cholesterol, and phospholipid content of the Sf 0–12, 20–60, and 60–400 lipoproteins (all P = 0.001). Lecithin: cholesterol acyl transferase activity was not altered. The postprandial increase in VLDL cholesterol 5 h after a standardized mixed meal was attenuated after pravastatin treatment (P = 0.011). Inhibition of hepatic cholesterol synthesis with an HMG-CoA reductase inhibitor in hyperlipidemic patients with NIDDM decreased serum cholesterol content of triglyceride-rich lipoprotein, thereby decreasing the transfer of cholesteryl ester from HDL to LDL and VLDL.
Impaired Activation of Glucose Oxidation and NADPH Supply in Human Endothelial Cells Exposed to H2O2 in High-Glucose Medium
Authors: Asahina Takayuk , Kashiwagi Atsunori , Nishio Yoshihiko , Ikebuchi Motoyoshi , Harada Natsuki , Tanaka Yasushi , Takagi Yoshihumi , Saeki Yukikazu , Kikkawa Ryuichi , Shigeta Yukio
Published: September 2013

The effects of glucose concentration on D-glucose oxidation and reduced nicotinamide adenine dinucleotide phosphate (NADPH) supply were studied during exposure of cultured human umbilical vein endothelial cells to hydrogen peroxide (H2O2). The activation of glucose oxidation via the pentose phosphate pathway (PPP), induced by exposure of cells to 200 μmol/l H2O2 for 1 h, was reduced by 50% (P < 0.01) in cells cultured for 5–7 days in 33 mmol/l D-glucose (HG) versus those cultured in 5.5 mmol/l D-glucose without (NG) or with (HR) 27.5 mmol/l D-raffinose. The intracellular NADPH content in HG cells, but not in NG or HR cells, was decreased by 42% (P < 0.01) by exposing cells to 200 μmol/l H2O2. The decrease in NADPH was dependent on D-glucose concentration in the medium and was prevented in glutathione (GSH)-depleted cells. The latter observation suggests that the decrease in NADPH is associated with activation of the GSH redox cycle. In the presence of 200 μmol/l H2O2, lactate release into the medium, NADH/NAD ratio, and phosphofructokinase activity in HG cells were 56, 53, and 68% greater, respectively, than in the NG group, which indicates that inhibition of glycolysis by H2O2 is less marked in the HG group compared with NG group. These results indicate that activation of the PPP was impaired in endothelial cells cultured under conditions of high-glucose and oxidative stress, resulting in a decreased supply of NADPH to various NADPH-dependent pathways, including the GSH redox cycle.
DRB1*0403 Protects Against IDDM in Caucasians With the High-Risk Heterozygous DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 Genotype
Authors: Van der Auwera Bart , Van Waeyenberge Christine , Schuit Frans , Heimberg Harry , Vandewalle Christina , Gorus Frans , Flament Jocelyne ,   Belgian Diabetes Registry
Published: September 2013

The human leukocyte antigen (HLA) class II genotype DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 has been identified as a marker strongly predisposing to insulin-dependent diabetes mellitus (IDDM) in Caucasian populations. Its frequency in control populations (1–3%) is still, however, 1 order of magnitude higher than the prevalence of IDDM, suggesting that its penetrance can be modified by protective factors. In this study we searched for such a factor in the DRB1 locus by studying DRB1*04 polymorphism in 174 European Caucasian IDDM patients and 73 nondiabetic control subjects, all sharing the HLA-DR3/DR4 phenotype. Significant protection was encoded by the DRB1*0403 allele, which was observed in 5 of 49 control subjects (10%) and none of 171 IDDM patients (0%) with the DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 genotype (RR = 0.02 [0.01–0.18], P < 0.0005). These data support the concept that protective HLA class II genes can overrule the risk caused by HLA-DQ susceptibility dimers. They also contribute to a possible strategy to screen for nondiabetic individuals with increased genetic risk of developing IDDM.
Skeletal Muscle GLUT4 Protein Concentration and Aging in Humans
Authors: Houmard Joseph A , Weidner Melinda D , Dolan Patrcia L , Leggett-Frazier Nancy , Gavigan Karen E , Hickey Matthew S , Tyndall Gilian L , Zheng Donghai , Alshami Ayman , Dohm G Lynis
Published: September 2013

The insulin resistance of aging has been attributed to a postreceptor defect in skeletal muscle. The present study examined whether a reduction in the concentration of the insulin-stimulated glucose transporter (GLUT4) in skeletal muscle was associated with advancing age in men (n = 55) and women (n = 29). Insulin sensitivity (minimal model) was negatively associated (P > 0.001) with age (range, 18–80 years) in men (r = −0.44) and women (r = −0.58). GLUT4 protein concentration in the vastus lateralis was also negatively associated (P < 0.05) with age (men, r = −0.28; women, r = −0.51). There was no relation (P > 0.15) between GLUT4 content in the gastrocnemius and age. GLUT4 concentration in the vastus lateralis was positively associated (P < 0.01) with insulin sensitivity in both sexes (r = 0.42); this relationship persisted in the men after adjusting for overall adiposity, regional adiposity, and cardiorespiratory fitness. These findings suggest that a decrement in GLUT4 protein concentration in skeletal muscle may at least partially contribute to the insulin resistance of aging in humans.
Role of Blood Flow and Impaired Autoregulation in the Pathogenesis of Diabetic Retinopathy
Authors: Kohner Eva M , Patel Vinod , Rassam Salwan M B
Published: September 2013

Several mechanisms are implicated in the pathogenesis of diabetic retinopathy. They include biochemical, hemodynamic, and hormonal factors, all of which have an important role in the development of diabetic retinopathy. These factors are not independent of each other, but rather they interact and together are responsible for the well-known lesions of vascular occlusion, microaneurysms, hemorrhages' hard exudates, and eventually new vessel formation.
Insulin Gene Region-Encoded Susceptibility to IDDM Maps Upstream of the Insulin Gene
Authors: Undlien Dag E , Bennett Simon T , Todd John A , Akselsen Hanne E , Ikäheimo Irma , Reijonen Helena , Knip Mikael , Thorsby Erik , Rønningen Kjersti S
Published: September 2013

The gene region on chromosome 11p15.5 known to be involved in insulin-dependent diabetes mellitus (IDDM) susceptibility was recently mapped to a 4.1-kilobase region including the insulin gene. The region contains 10 candidate polymorphisms that are in strong linkage disequilibrium. By genotyping 7 of these 10 polymorphisms and the tyrosine hydroxylase microsatellite in Finnish Caucasoid IDDM patients and control subjects, we demonstrate that many of the polymorphisms found to be associated with IDDM in other Caucasoid populations do not show any association in this Finnish population. Of the polymorphisms typed, only those at –23 Hph I and the variable number of tandem repeats (VNTR) sites confer significant relative risk. Furthermore, we have demonstrated that the –23 Hph I polymorphism cannot explain the association. Comparison of the genotypic patterns observed here and previously suggests that the VNTR is the most likely candidate for IDDM2. The VNTR is located adjacent to defined regulatory DNA sequences affecting insulin gene expression, which suggests a possible effect on expression of insulin or one of the neighboring genes, tyrosine hydroxylase or insulin-like growth factor 2.
Interferon Expression in the Pancreases of Patients With Type I Diabetes
Authors: Huang Xiaojian , Yuang Jean , Goddard Audrey , Foulis Alan , James Roger F L , Lernmark Åke , Pujol-Borrell Ricardo , Rabinovitch Alex , Somoza Nuria , Stewart Timothy A
Published: September 2013

We have used a reverse transcriptase–polymerase chain reaction (RT-PCR) protocol to examine the expression of cytokines in the pancreases and islets of patients with type I diabetes. We detect a significant increase in the level of expression of interferon (IFN)-α in the pancreases of the diabetic patients as compared with the control pancreases. In contrast, IFN-β was detected at comparable levels in both groups, while IFN-γ was detected in three of four control pancreases and one of four pancreases from the diabetic individuals. The IFN-α cDNAs generated by the RT-PCR were cloned and sequenced to determine which α-subtypes were being expressed. We found that the repertoire of subtypes was quite limited in any one individual (diabetic or not), although each individual was different with respect to the pattern of subtypes expressed. We also examined these pancreases for the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1α, IL-2, IL-4, and IL-6. We found no detectable expression of TNF-α or IL-2 in any pancreases, and the expression of the other cytokines was variable, with no pattern emerging from the comparison of the diabetic and nondiabetic individuals. We conclude that, of the cytokines examined, only IFN-α was significantly increased in the diabetic patients, a result that is consistent with the possibility that this cytokine is directly involved in the development of type I diabetes.
31P–Nuclear Magnetic Resonance Evidence of an Activated Hexose-Monophosphate Shunt in Hyperglycemic Rat Lenses In Vivo
Authors: Szwergold Benjamin S , Lal Sundeep , Taylor Anne H , Kappler Francis , Su Bangying , Brown Truman
Published: September 2013

Using 31P–nuclear magnetic resonance spectroscopy, we have identified elevated concentrations of sedoheptulose-7-phosphate (S-7-P) in lenses from three animal models of hyperglycemia: streptozotocin-induced diabetic rats, galactose-fed rats, and xylose-fed rats. This observation provides a unique and independent confirmation of the activation of the hexose monophosphate shunt (HMPS) pathway in the hyperglycemic lens in vivo. While the elevation in concentration of S-7-P was very dramatic, the other HMPS metabolites in these tissues were below the threshold of detection, as expected for the HMPS pathway near equilibrium. In terms of nonenzymatic glycation, these results suggest that the only HMPS metabolite of importance in the hyperglycemic rat lens is S-7-P. Although in the diabetic lens its role appears to be relatively minor, in the galactosemic lens this compound may be an important contributor to the increased production of advanced glycosylation end products.
Human Obese Gene Expression: Adipocyte-Specific Expression and Regional Differences in the Adipose Tissue
Authors: Masuzaki Hiroaki , Ogawa Yoshihiro , Isse Naohi , Satoh Noriko , Okazaki Taku , Shigemoto Michika , Mori Kiyoshi , Tamura Naohisa , Hosoda Kiminori , Yoshimasa Yasunao , Jingami Hisato , Kawada Teruo , Nakao Kazuwa
Published: September 2013

The obese (ob) gene, the mutation of which results in severe hereditary obesity and diabetes in mice, has recently been isolated through positional cloning. In this study, we isolated a full-length human ob complementary DNA (cDNA) clone and examined the tissue distribution of ob gene expression in humans. The nucleotide sequences of the human ob cDNA coding region were 83% identical to those of the mouse and rat ob cDNA coding regions. Analysis of the deduced amino acid sequences revealed that the human ob protein is a 166–amino acid polypeptide with a putative signal sequence and is 84 and 83% homologous to the mouse and rat ob proteins, respectively. Northern blot analysis using the cloned human ob cDNA fragment as a probe identified a single messenger RNA (mRNA) species 4.5 kb in size found abundantly in the adipose tissues obtained from the subcutaneous, omental, retroperitoneal, perilymphatic, and mesenteric fat pads. However, no significant amount of ob mRNA was present in the brain, heart, lung, liver, stomach, pancreas, spleen, small intestine, kidney, prostate, testis, colon, or skeletal muscle. The ob mRNA level in the adipose tissue varied from region to region even in the same individual. Furthermore, in the human adipose tissue, ob gene expression occurred in mature adipocytes rather than in stromal-vascular cells. This study is the first report of the elucidation of ob gene expression in human tissues, thereby leading to better understanding of the physiological and clinical implications of the ob gene.
Effect of a Specific Endothelin Receptor A Antagonist on mRNA Levels for Extracellular Matrix Components and Growth Factors in Diabetic Glomeruli
Authors: Nakamura Tsukasa , Ebihara Isao , Fukui Mitsumine , Tomino Yasuhiko , Koide Hikaru
Published: September 2013

We have previously reported that the mRNA levels of extracellular matrix (ECM) components including αl(I), αl(III), and αl(IV) collagen chains, laminin Bl and B2 chains, and growth factors including tumor necrosis factor (TNF)-α, platelet-derived growth factor (PDGF)-B chain, transforming growth factor (TGF)-β, and basic fibroblast growth factor (FGF) all increase with age in diabetic glomeruli. The present study was designed to assess whether glomerular expression of these mRNAs in rat diabetic glomeruli is affected by a specific endothelin receptor A antagonist, FR139317. Diabetes was produced by streptozotocin injection, and animals were divided into four groups: untreated diabetic rats, FR139317-treated diabetic rats, control nondiabetic rats, and FR139317-treated control rats. FR139317 treatment was continued for 24 weeks. FR139317 attenuated the rise in creatinine clearance (P < 0.01) and reduced urinary protein excretion (P < 0.01) in diabetic rats, but did not affect blood pressure. FR139317 attenuated the increases in glomerular mRNA levels of αl(I) (P < 0.01), α1(III) (P < 0.01), and α1(IV) (P < 0.01) collagen chains, laminin B1 (P < 0.01) and B2 (P < 0.01) chains, TNF-α (P < 0.01), PDGF-B (P < 0.01), TGF-β (P < 0.001) and basic FGF (P < 0.01) in diabetic rats. However, FR139317 did not affect these mRNA levels in glomeruli of control rats. These findings suggest that FR139317 may be useful in the treatment of diabetic glomerulopathy by reducing mRNA levels of ECM components and growth factors.
Decreased Degradative Enzymes in Mesangial Cells Cultured in High Glucose Media
Authors: Leehey David J , Song Ruo Hua , Alavi Nahid , Singh Ashok K
Published: September 2013

Abnormalities in extracellular matrix degradation may play a pathogenetic role in diabetic nephropathy. Cultured renal mesangial cells are known to synthesize increased amounts of matrix proteins when incubated in high glucose media (e.g., 30 mmol/l). However, the effect of glucose loading on degradative enzymes is unknown. Primary cultures of rat mesangial cells were grown until confluent in the presence of fetal calf serum (FCS) and insulin (0.67 U/ml). Cells were then cultured for 7 days in plastic wells in either 10 or 30 mmol/1 glucose media containing neither FCS nor insulin. Collagenase activity in media were determined by zymography and quantitative spectrofluorometry. Cathepsin B and D activities in cell extracts were measured by spectrofluorometry (using the fluorescent substrate Z-Arg-Arg-7-amido-4-methylcoumarin) and 125I-labeled hemoglobin digestion, respectively. Gelatin-degrading activity of live mesangial cells was also determined. mRNA levels for collagenase IV, cathepsin B, and cathepsin D were determined by Northern analysis. A major band of collagenase activity with a molecular size of 72 kDa was observed in all mesangial cell media. Exposure of cells to high glucose media resulted in significant reductions in collagenase and cathepsin B activities as well as impairment in gelatin-degrading activity. Collagenase IV and cathepsin B and D mRNA levels were also decreased by glucose loading. To exclude the possibility that glucose loading was injurious to cells, 3H-leucine uptake (as a measure of protein synthesis) and membrane alkaline phosphatase activity (as a biochemical marker of viability) were not affected by the high glucose condition. We conclude that proteinase activity is decreased in mesangial cells incubated in high glucose media. This may be due to changes in levels of gene expression (mRNA) of these enzymes.
Insulin Sensitivity Accounts for Glucose and Lactate Kinetics After Intravenous Glucose Injection
Authors: Watanabe Richard M , Lovejoy Jennifer , Steil Garry M , DiGirolamo Mario , Bergman Richard N
Published: September 2013

Mathematical modeling was used to explore the interaction between glucose, insulin, and lactate during the frequently sampled intravenous glucose tolerance test (FSIGTT). Insulin-modified FSIGTs were performed in 25 lean volunteers, and an additional 5 volunteers underwent FSIGTs with glucose injection alone to illustrate the effect of insulin on both glucose and lactate kinetics. The model chosen as the best representation of the system extended the minimal model of glucose kinetics (MM) by including a two-compartment model of lactate kinetics. The model accounted for both glucose and lactate kinetics, provided traditional MM parameters of insulin sensitivity and glucose effectiveness, and descriptive parameters of lactate kinetics. Modeling suggested that lactate production was limited by the rate of glucose disappearance, with no indication of direct effects of insulin on lactate. Inclusion of lactate kinetics had no adverse effect on MM parameters (SG: 0.023 ± 0.009 vs. 0.023 ± 0.010 min−1,SI: 1.01 ± 0.70 vs. 1.03 ± 0.71 × 104 · min−1 · pmol−1 · 1; P < 0.50, lactate model vs. MM), and indicated that ∼1.2% min−1 of total glucose disappearance during the FSIGT is converted to lactate. An additional benefit of including lactate kinetics was the significant improvement in precision in MM parameter estimates as reflected by the fractional standard deviations (FSDs). This effect was most prominent for SG, in which a threefold improvement in parameter precision was observed (FSD: 13.5 ± 3.1 vs. 42.5 ± 48.5; means ± SD). These analyses indicate that kinetic information for both glucose and lactate can be derived from FSIGT data and provide insights into the interaction between glucose, insulin, and lactate under non-steady-state conditions.
Human Leukocyte Antigen Identity and DQ Risk Alleles in Autoantibody-Positive Siblings of Children With IDDM are Associated With Reduced Early Insulin Response
Authors: Veijola Riitta , Vähäsalo Paula , Tuomilehto-Wolf Eva , Reijonen Helena , Kulmala Petri , Ilonen Jorma , Åkerblom Hans K , Knip Mikael ,   Childhood Diabetes in Finland (DiMe) Study Group
Published: September 2013

To investigate the relationship between human leukocyte antigen (HLA)-associated genetic factors and the development of β-cell dysfunction, we performed sequential intravenous glucose tolerance tests (IVGTTs) on 81 islet cell antibody (ICA)-positive and/or insulin autoantibody-positive healthy siblings of children with newly diagnosed insulin-dependent diabetes mellitus (IDDM). A lower glucose disappearance rate (Kg) (P < 0.5) and decreased first-phase insulin response (FPIR) (P < 0.05) were observed on multiple occasions in HLA-identical siblings compared with the haploidentical or nonidentical ones. Siblings carrying the DQB1*0302/0201, −0302/x, or −0201/x genotype also had lower FPIRs (P ≤ 0.05) at several time points than those with no DQB1 risk genotype. When all IVGTTs were taken into account, DQB1*0302/0201 heterozygous siblings had an abnormally low FPIR (< 45 mU/I; 3rd percentile) in at least one test more often than did siblings with no DQB1 risk genotype (50.0% vs. 6.1%; P = 0.001). Siblings carrying either the DQB1*0602 or the DQB1*0603 protective allele had lower serum peak ICA and glutamic acid decarboxylase (GAD)65 antibody levels (P = 0.023 and 0.007, respectively) and higher FPIRs on several occasions (P < 0.05) than those with the DQB1 risk genotypes. Progression to IDDM was related to both HLA identity and the presence of the DQB1*0302/0201 genotype. Normal Kg and FPIR levels were observed in siblings who were positive for only insulin autoantibody, and none of them developed IDDM. Serum ICA concentrations were inversely correlated with Kg (rs = −0.41; P < 0.001) and FPIR (rs = −0.52; P < 0.001) in the first IVGTT, suggesting that high serum levels of ICA could to some extent be used as an indicator of impaired insulin-secretory capacity in the β-cells. We conclude that both HLA identity and the presence of DQB1 risk genotype were associated with a decreased early insulin response to intravenous glucose in ICA+ siblings of diabetic children. HLA identity was also associated with impaired glucose tolerance.
Enhanced Anticoagulant Response to Activated Protein C in Patients With IDDM
Authors: Krugluger Walter , Kopp Hans-Peter , Schernthaner Guntram , Hopmeier Pierre
Published: September 2013

Anticoagulant response to activated protein C (APC) was studied in 40 healthy subjects and 67 patients with insulin-dependent diabetes mellitus (IDDM) using a modified activated thromboplastin time assay. Results are expressed in terms of the APC sensitivity ratio (APC SR). In addition, plasma levels of protein C, total and free protein S (PS), coagulation factors V and VIII, and prothrombin fragment 1+2 (F1+2) were measured. Patients with IDDM and a urinary albumin excretion rate (UAER) <30 mg/24 h showed a median APC SR of 2.5 (interquartile range 2.3–2.9). In patients with a UAER between 30 and 300 mg/24 h, the median APC SR was 2.7 (2.7–2.9). Both values were significantly greater than the median APC SR of 2.1 (2.0–2.5) observed in healthy control subjects (P < 0.001). Also, the percentage of subjects with an APC SR ≤2.0 was markedly smaller in both patient groups. Factor V and VIII levels were not significantly different between IDDM patients and healthy subjects. Grouping of IDDM patients according to the APC SR revealed significantly enhanced levels of total PS (P < 0.05) and factor VIII (P < 0.01) in patients with a poor anticoagulant response to APC (APC SR ≤2.0) compared with those with an APC SR >2.7. The negative correlation of the APC SR in diabetic patients with both coagulation and anticoagulation factors indicates a complex role of this parameter in regulating the coagulation system in IDDM.
Free Fatty Acid as a Link in the Regulation of Hepatic Glucose Output by Peripheral Insulin
Authors: Rebrin Kerstin , Steil Garry M , Getty Lisa , Bergman Richard N
Published: September 2013

Overproduction of glucose by the liver in the face of insulin resistance is a primary cause of hyperglycemia in non-insulin-dependent diabetes mellitus (NIDDM). However, mechanisms involved in control of hepatic glucose output (HGO) remain less than clear, even in normal individuals. Recent results have supported an indirect extrahepatic effect of insulin as the primary locus of insulin action to restrain HGO. One suggested extrahepatic site is the pancreatic ɑ-cell. To examine whether insulin's extrahepatic site is independent of the ɑ-cells, HGO suppression was examined independent of changes in glucagon secretion or insulin antagonism of glucagon action. Euglycemic glucose clamps (n = 40) with somatostatin infusion were performed in conscious dogs (n = 5). Paired experiments were conducted in which insulin was infused either portally (1.2, 3.0, 6.0 pmol · min−1 · kg−1) or peripherally at half the portal infusion rate (0.6, 1.5, 3.0 pmol · min−1 · kg−1). Additional zero and saturating portal-dose experiments (100 pmol · min−1 · kg−1) were also performed. For the paired experiments, portal insulin infusion resulted in portal insulin concentrations approximately two to three times higher than in the corresponding peripheral insulin infusion experiments, while at the same time peripheral insulin concentrations were approximately matched. Equal peripheral insulin concentration resulted in equivalent HGO suppression irrespective of the portal concentrations. Thus, insulin affects a signal at a peripheral site, other than ɑ-cell, that in turn suppresses hepatic glucose production. To investigate the nature of this signal, we measured alanine, lactate, and free fatty acids (FFAs). There was no clear relationship between alanine or lactate and HGO suppression; however, there was an extremely strong relationship between plasma FFAs and HGO both at steady state and during dynamic changes in insulin. These data suggest, but do not prove, that insulin acts to suppress HGO as follows: Insulin slowly traverses the capillary endothelium in adipose tissue; elevated insulin in adipose tissue interstdtium inhibits lipolysis, thus decreasing FFA levels; and decreased FFAs act as a signal to the liver to suppress endogenous glucose production.
Lipid and Carbohydrate Metabolism in IDDM During Moderate and Intense Exercise
Authors: Raguso Comasia A , Coggan Andrew R , Gastaldelli Amalia , Sidossis Labros S , Bastyr Edward J , Wolfe Robert R
Published: September 2013

Insulin-dependent diabetes mellitus (IDDM) is characterized by a metabolic and hormonal disarray that may be more evident during exercise. However, the metabolic response to exercise of different intensities has not been evaluated in IDDM. We therefore used stable isotope techniques and indirect calorimetry to quantify substrate kinetics and oxidation during 30 min of exercise at 45 and 75% of maximal oxygen uptake (Vo2max) in seven men with IDDM (D group) infused with insulin at a constant basal rate. Normal control subjects (C group) matched for age, weight, and Vo2max were also studied. During moderate exercise, glucose uptake (Rd) was lower in the D than in the C group (15.3 ± 1.0 vs. 20.8 ± 1.6 μmol · min−1 · kg−1; P < 0.05). Carbohydrate oxidation also tended to be lower in the D group (71.0 ± 7.2 vs. 87.5 ± 10.6 μmol · min−1 · kg−1; P = 0.08). The D group relied on fat oxidation to a greater extent than did the C group (16.9 ± 1.1 vs. 10.4 ± 1.6 μmol · min−1 · kg−1; P < 0.05). The enhanced fat oxidation was not due to increased lipolysis because no differences occurred in glycerol release (Ra) or in plasma free fatty acid Ra or concentration, and the source of the extra lipid appeared to be intramuscular fat stores. These differences in substrate metabolism were not evident during exercise at 75% of Vo2max. The lower glucose uptake and oxidation in the diabetic subjects during moderate, but not intense, exercise suggest that glucose metabolism is regulated differently depending on exercise intensity. During moderate exercise, glucose uptake into muscle seems to be limiting, and the higher intramuscular triglyceride oxidation observed in IDDM might be a compensatory adaptation needed to maintain energy supply.
Genetic Analysis of NIDDM: The Study of Quantitative Traits
Authors: Ghosh Soumitra , Schork Nicholas J
Published: September 2013

Many studies are in progress worldwide to elucidate the genetics of NIDDM. Nevertheless, few articles are available that combine the interdisciplinary fields of medicine, genetics, physiology, and statistics in order to provide the scientific rationale for such an endeavor. Here we describe the methodology and background necessary to study the genetics of NIDDM and discuss how to analyze the data. We also provide a detailed bibliography for researchers and a glossary for those who are not experts in the field. In particular, we wish to emphasize the analysis of intermediate quantitative traits as a means to dissect the genetic basis of NIDDM.
Long-Term Results of Early Cyclosporin Therapy in Juvenile IDDM
Authors: Filippo Gianpaolo De , Carel Jean-Claude , Boitard Christian , Bougnères Pierre-Francois
Published: September 2013

In juvenile IDDM patients, immunosuppression with cyclosporin A allows partial beta-cell function recovery and transient remissions of insulin dependency. The effects of this therapeutic approach, however, have not been evaluated in the long-term, since no reported trial exceeded 1 year. Here we analyze 130 diabetic children followed at our institution during the first years of their disease. Cyclosporin was given to 83 of them at an initial dose of 7.2 ± 0.1 mg·kg−1·day−1, which was decreased stepwise then interrupted after 6–62 months, depending on the response to therapy. A total of 47 diabetic children, who served as control subjects in two trials, were pooled for comparison. Over 4 years, the cyclosporin-treated group kept plasma C-peptide ∼ twice as high as the control group (P < 0.02). It took 5.8 ± 0.6 years for C-peptide secretion stimulated by glucagon to become undetectable in the cyclosporin group versus 3.2 ± 0.6 years in the control group (P < 0.02). Average insulin dose remained lower by 0.2–0.4 U·kg−1·day−1 and glycated hemoglobin by ∼ 1% in cyclosporin-treated patients (P < 0.02), who also had less hypoglycemia than the diabetic control subjects (P < 0.05). After 4 years, differences between the groups became nonsignificant. We observed no significant secondary effects of cyclosporin. In conclusion, positive effects of low-dose cyclosporin in recently diagnosed clinical IDDM patients are prolonged beyond interruption of the drug. The magnitude and duration of the benefit, however, do not appear sufficient to justify this immunosuppressive treatment in clinical practice.
Effects of Insulin on Vascular Tone and Sympathetic Nervous System in NIDDM
Authors: Tack Cees J J , Smits Paul , Willemsen Jacques J , Lenders Jacques W M , Thien Theo , Lutterman Jos A
Published: September 2013

Chronic activation of the sympathetic nervous system may be a pathogenetic mechanism by which hyperinsulinemia induces cardiovascular damage in insulin-resistant NIDDM patients. The influence of physiological hyperinsulinemia (∼ 700 pmol/l) on basal and stimulated sympathetic outflow was studied in 12 lean normotensive subjects with well-controlled NIDDM without complications and in 13 matched control subjects. Forearm blood flow (FBF) was measured with forearm plethysmography; sympathetic nervous system activity was assessed by the [3H]norepinephrine (NE) tracer method. NIDDM patients were insulin resistant (glucose infusion rates 31.8 ± 3.8 vs. 48.7 ± 2.0 mumol·kg−1 · min−1 in control subjects, P < 0.01). After a mixed meal, NIDDM patients showed a hyperinsulinemic response (2-h insulin levels: NIDDM patients 324 ± 34 pmol/l, control subjects 165 ± 19 pmol/l, P < 0.001). Insulin infusion induced a vasodilator response (not significantly different between the groups). Arterial plasma NE levels and total-body NE spillover increased significantly (total spillover in NIDDM patients from 0.77 ± 0.09 to 1.18 ± 0.16 nmol · m−2 · min−1, in control subjects from 0.98 ± 0.14 to 1.23 ± 0.18 nmol · m−2 · min−1 P < 0.01 for all, not different between groups). Total-body NE clearance did not change. Sympathetic stimulation (lower-body negative pressure [LBNP] 15 mmHg) induced forearm vasoconstriction and increased arterial and venous plasma NE and total NE spillover. Responses of FBF and NE kinetics to LBNP were not significantly different between groups and were not altered by hyperinsulinemia. Although these nonobese subjects with uncomplicated NIDDM showed postprandial hyperinsulinemia and resistance to the effect of insulin on glucose metabolism, this group was not resistant to the vasodilator and sympathetic stimulant effects of insulin. Responses to sympathetic stimuli (LBNP) were normal and unaffected by physiological hyperinsulinemia. Therefore, because of daily life hyperinsulinemia, chronic sympathetic stimulation could be operative in these patients and may explain the increased incidence of hypertension and/or cardiovascular complications.
Improvement of Insulin Action in Diabetic Transgenic Mice Selectively Overexpressing GLUT4 in Skeletal Muscle
Authors: Leturque Armelle , Loizeau Martine , Vaulont Sophie , Salminen Marjo , Girard Jean
Published: September 2013

To investigate the role of glucose transporter expression in whole-body glucose homeostasis, we have created transgenic mice that have a 2.0- to 3.5-fold increase in GLUT4 glucose transporter level in skeletal muscle and heart. This increase is sufficient to significantly improve insulin action and to reduce basal blood glucose levels in transgenic streptozotocin-induced diabetic mice. These results provide the first evidence of a direct causality between skeletal muscle GLUT4 transporter level and overall insulin responsiveness.
Galactosemic Neuropathy in Transgenic Mice for Human Aldose Reductase
Authors: Yagihashi Soroku , Yamagishi Shin-Ichiro , Wada Ryuichi , Sugimoto Kazuhiro , Baba Masayuki , Wong Hong-Gang , Fujimoto Junichiro , Nishimura Chihiro , Kokai Yasuo
Published: September 2013

We studied the functional consequences of an enhanced polyol pathway activity, elicited with galactose feeding, on the peripheral nerve of transgenic mice expressing human aldose reductase. Nontransgenic littermate mice were used as controls. With a quantitative immunoassay, the expression level of human aldose reductase in the sciatic nerve was 791 ± 44 ng/mg protein (mean ± SE), about 25% of that in human sural nerve. When the transgenic mice were fed food containing 30% galactose, significant levels of galactitol accumulated in the sciatic nerve. Galactose feeding of nontransgenic littermate mice led to a 10-fold lower accumulation of galactitol. Galactose feeding for 16 weeks caused a significant and progressive decrease in motor nerve conduction velocity in transgenic mice to 80% of the level of galactose-fed littermate mice, which was not significantly different from that of galactose-free littermate mice. A morphometric analysis of sciatic nerve detected > 10% reduction of mean myelinated fiber size but no alterations of myelinated fiber density in galactose-fed transgenic mice compared with other groups. The functional and structural changes that develop in galactose-fed transgenic mice are similar to those previously reported in diabetic animals. The results of these studies suggest that transgenic mice expressing human aldose reductase may be a useful model not only for defining the role of the polyol pathway in diabetic neuropathy but also for identifying and characterizing effective inhibitors specific for human aldose reductase.
Pancreatic Regenerating Gene Overexpression in the Nonobese Diabetic Mouse During Active Diabetogenesis
Authors: Baeza Nathalie J , Moriscot Christine I , Renaud Wanda P , Okamoto Hiroshi , Figarella Catherine G , Vialettes Bernard H
Published: September 2013

The reg gene has previously been shown to be associated with regeneration of pancreatic islets. Strategies for influencing the replication and the growth of the β-cell mass may be important for prevention and/or treatment of type I diabetes. In this study, we have examined the level of reg gene expression at various degrees of diabetogenesis in the pancreas of the NOD mouse (male, female, and cyclophosphamide-treated male) using both human reg cDNA as the probe and dot blot analysis. The expression of the reg gene was found to be significantly increased in female mice compared with male mice, and in both cases, the expression level was not influenced by age. Nondiabetic female mice have a significantly higher expression of the gene than diabetic female mice, and there was a positive correlation between the age of diabetes onset and the reg mRNA level. In addition, overexpression of the reg gene was found in male mice treated by cyclophosphamide, an agent known to be a potent inducer of diabetes in male NOD mice. None of these results were found in the diabetes-resistant control OF1 mice, in which pancreatic reg gene expression did not differ between female and male mice treated or untreated with cyclophosphamide. All of these data suggest that there is a strong correlation between reg gene expression in the pancreas of the NOD mouse and the likelihood of developing diabetes.
Effect of Risk Factors on Exercise Capacity in NIDDM
Authors: Estacio Raymond O , Wolfel Eugene E , Regensteiner Judith G , Jeffers Barrett , Havranek Edward P , Savage Susan , Schrier Robert W
Published: September 2013

Exercise capacity has been used as a noninvasive parameter for predicting cardiovascular events. It is known that diabetic patients have an impaired exercise capacity when compared with nondiabetic age-matched control subjects, but the risk factors associated with this impairment have not been thoroughly analyzed. A total of 453 male and female NIDDM patients who underwent graded exercise testing with expired gas analysis were studied to determine the possible influences of demographic and cardiac risk factors on exercise capacity. Univariate and multiple linear regression analyses were performed on baseline patient characteristics with respect to peak oxygen consumption (VO2). In the regression analyses, African-American race was strongly associated with a decrease in peak VO2; the difference in means between African-Americans and other subjects for men was −2.50 ml.kg−1 · min−1 (−4.28, −0.07, 95% CI) (P < 0.006) and for women was −2.96 ml.kg−1 · min−1 (−4.45, −1.47) (P < 0.0002). Univariate analyses revealed that African-American subjects had increased prevalence, longer duration, and higher systolic and diastolic hypertension than the non-Hispanic and Hispanic whites. Other independent predictors of peak VO2 (reported as change in peak VO2 in milliliters per kilogram per minute) were BMI (men: −0.39 kg/m2 [−0.52, −0.29], P < 0.0001; women: −0.39 kg/m2 [−0.48, −0.31], P < 0.0001), age (men: −0.16/year [−0.23, −0.09], P < 0.0001; women: −0.17/year [−0.24, −0.11], P < 0.0001), baseline resting systolic blood pressure (men: −0.03/mmHg [−0.06, −0.01], P < 0.05; women: −0.03/mmHg (−0.06, −0.01], P< 0.05), and pack-years smoking (men: −0.04/pack-years [−0.04, −0.01], P < 0.01; women: −0.04/pack-years [−0.07, −0.01], P < 0.0001). Thus, in this large NIDDM study, weight loss, smoking cessation, and aggressive blood pressure control, particularly in African-Americans with NIDDM, would appear to be important in improving exercise capacity and potentially improving the increased cardiovascular mortality associated with an impaired exercise capacity.
Recombinant Human Insulin-Like Growth Factor I Increases Insulin Sensitivity and Improves Glycemic Control in Type II Diabetes
Authors: Moses Alan C , Young Simon CJ , Morrow Linda A , O'Brien Maureen , Clemmons David R
Published: September 2013

Insulin resistance is a major factor in the pathophysiology of type II diabetes and a major impediment to successful therapy. The identification of treatments that specifically target insulin resistance could improve diabetes management significantly. Since IGFs exert insulin-like actions and increase insulin sensitivity when administered at supraphysiological doses, we determined the effect of 6 weeks of recombinant human IGF-I (rhIGF-I) administration on insulin resistance and glycemic control in obese insulin-resistant patients with type II diabetes. A total of 12 patients with type II diabetes were recruited for the study. Subcutaneous administration of rhIGF-I (100 μg/kg b.i.d.) significantly lowered blood glucose. Fructosamine declined from 369 to 299 µmol/l by 3 weeks of administration and then declined further to 271 at the end of 5 weeks. Glycosylated hemoglobin, which was 10.4% pretreatment, declined to 8.1% at the end of therapy. Mean 24-h blood glucose during a modal day was 14.71 ± 4.5 mmol/l pretreatment and declined to 9.1 ± 3.21 mmol/l by the end of treatment. These improvements in glycemia were associated with a decrease in serum insulin levels. Mean insulin concentrations declined from 108.0 to 57.0 pmol/l during the modal day measurements and from 97.2 to 72.0 pmol/l during the mixed-meal tolerance test. Changes in glycemia were accompanied by a marked increase in insulin sensitivity. The insulin sensitivity index (SI) calculated from a frequently sampled intravenous glucose tolerance test (FSIVGTT) after the method of Bergman et al. (Bergman RN, Finegold DT, Ader M: Assessment of insulin sensitivity in vivo. Endocr Rev 6:45–86, 1985) increased 3.4-fold. Furthermore, the improvement in glycemic control was accompanied by a change in body composition with a 2.1% loss in body fat as calculated by dual energy x-ray absorptiometry without change in total body weight. Significant side effects were present in some subjects, although nine subjects were able to complete at least 4.5 weeks of the protocol and six subjects completed the entire 6 weeks. Supraphysiological IGF-I concentrations were maintained throughout the study, increasing from 206¼g/l in the control period to 849 ¼g/l at the end of 6 weeks of rhIGF-I treatment. The increase in IGF-I levels was accompanied by a significant increase in IGF binding protein-2 levels, a slight reduction in IGF binding protein-3 levels, and an increase in levels of IGF binding protein-1. In summary, IGF-I significantly lowered blood glucose as reflected by short-term and long-term indexes of glycemic control and increased insulin sensitivity. It remains to be determined whether a dosage can be administered that avoids significant side effects and still achieves reasonable glycemic control.
Glucose Transport Activity in Insulin-Resistant Rat Muscle: Effects of Angiotensin-Converting Enzyme Inhibitors and Bradykinin Antagonism
Authors: Henriksen Erik J , Jacob Stephan , Augustin Hans J , Dietze Guenther J
Published: September 2013

Insulin resistance of skeletal muscle glucose disposal underlies the pathogenesis of NIDDM and is associated with hypertension, obesity, and dyslipidemia. Angiotensin-converting enzyme (ACE) inhibitors are used primarily in antihypertensive therapy but also are known to improve whole-body insulin-mediated glucose disposal. However, the exact site of action is not well characterized. We have used the isolated epitrochlearis muscle from a well-established animal model of skeletal muscle insulin resistance, the obese Zucker rat, to test the effect of oral administration of ACE inhibitors on insulin-sensitive muscle glucose transport activity. Both acute and chronic administration of a sulfhydiyl-containing ACE inhibitor (captopril) or a non–sulfhydryl-containing ACE inhibitor (tran-dolapril) significantly enhanced in vitro insulin-mediated muscle glucose transport activity. In addition, the acute effect of oral captopril administration was completely abolished by pretreatment of the animal with a bradykinin B2 receptor antagonist (HOE 140). These findings indicate that ACE inhibitors may improve whole-body glucose metabolism by acting on the insulinsensitive skeletal muscle glucose transport system. In addition, bradykinin or one of its metabolites may be involved in the action of the ACE inhibitor captopril on insulin-resistant muscle.