bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison Between the Minimal Model and the Glucose Clamp in the Assessment of Insulin Sensitivity Across the Spectrum of Glucose Tolerance
Authors: Saad Mohammed F , Anderson Randy L , Laws Ami , Watanabe Richard M , Kades Wagdy W , Chen Y -D Ida , Sands R Evan , Pei Dee , Savage Peter J , Bergman Richard N
Published: September 2013

An insulin-modified frequently sampled intravenous glucose tolerance test (FSIGTT) with minimal model analysis was compared with the glucose clamp in 11 subjects with normal glucose tolerance (NGT), 20 with impaired glucose tolerance (IGT), and 24 with non-insulin-dependent diabetes mellitus (NIDDM). The insulin sensitivity index (SI) was calculated from FSIGTT using 22- and 12-sample protocols (SI(22) and SI(12), respectively). Insulin sensitivity from the clamp was expressed as SI(clamp) and SIP(clamp). Minimal model parameters were similar when calculated with SI(22) and SI(12). SI could not be distinguished from 0 in ∼ 50% of diabetic patients with either protocol. SI(22) correlated significantly with SI(clamp) in the whole group (r = 0.62), and in the NGT (r = 0.53), IGT (r = 0.48), and NIDDM (r = 0.41) groups (P < 0.05 for each). SI(12) correlated significantly with SI(clamp) in the whole group (r = 0.55, P < 0.001) and in the NGT (r = 0.53, P = 0.046) and IGT (r = 0.58, P = 0.008) but not NIDDM (r = 0.30, P = 0.085) groups. When SI(22), SI(clamp), and SIP(clamp) were expressed in the same units, SI(22) was 66 ± 5% (mean ± SE) and 50 ± 8% lower than SI(clamp) and SIP(clamp), respectively. Thus, minimal model analysis of the insulin-modified FSIGTT provides estimates of insulin sensitivity that correlate significantly with those from the glucose clamp. The correlation was weaker, however, in NIDDM. The insulin-modified FSIGTT can be used as a simple test for assessment of insulin sensitivity in population studies involving nondiabetic subjects. Additional studies are needed before using this test routinely in patients with NIDDM.
Characterization of the Mechanism for the Chronic Activation of Diacylglycerol-Protein Kinase C Pathway in Diabetes and Hypergalactosemia
Authors: Xia Pu , Inoguchi Toyoshi , Kern Timothy S , Engerman Ronald L , Oates Peter J , King George L
Published: September 2013

Similar vascular pathological conditions are observed in diabetic animals and those with diet-induced hypergalactosemia. Both diabetes and hypergalactosemia are believed to cause vascular dysfunction via a common biochemical mechanism. In this study, we have found that both diabetes and hypergalactosemia in the short term (2–4 months) can increase total diacylglycerol (DAG) levels by 52 ± 9 and 74 ± 13% in the retina and aorta, respectively, of diabetic dogs, and by 94 ± 9 and 78 ± 11% in the retina and aorta, respectively, in dogs with hypergalactosemia as compared with normal control animals (P < 0.01). The elevation of DAG levels was maintained for 5 years in the aortas of diabetic and hypergalactosemic dogs. To characterize the mechanism of the DAG increases, we have determined that total DAG levels were significantly increased in cultured macro- and microvascular cells exposed to elevated glucose (22 mM) and galactose (16.5 mM) levels. These increased levels were not prevented by sorbinil, an aldose reductase inhibitor. One of the sources of the increased DAG levels was probably derived from de novo synthesis from both hexoses as determined by radiolabeling studies. Intracellularly, the DAG elevation activated protein kinase C (PKC) activity with increases of 58 ± 12% (P < 0.05) and 66 ± 8% (P < 0.01) in the membrane fraction of cultured aortic smooth muscle cells exposed to elevated glucose and galactose levels, respectively. These findings have clearly demonstrated a possible common biochemical mechanism by which hyperglycemia and hypergalactosemia can chronically activate the DAG-PKC pathway in the vasculature and could be a possible explanation for the development of diabetic vascular complications.
Accelerated β-cell Destruction in Adoptively Transferred Autoimmune Diabetes Correlates With an Increased Expression of the Genes Coding for TNF-α and Granzyme A in the Intra-Islet Infiltrates
Authors: Mueller Christoph , Held Werner , Imboden Martin A , Carnaud Claude
Published: September 2013

Autoimmune destruction of β-cells in nonobese diabetic (NOD) mice is greatly accelerated by adoptive cotransfer of syngeneic CD4+ and CD8+ T-cells from diabetic animals into newborn NOD mice. We followed, by in situ hybridization, the appearance of mRNA of the tumor necrosis factor (TNF)-α gene and, as a marker for activated cytotoxic T-cells, of the serine protease granzyme A gene in the cellular infiltrates generated by cell transfer at birth. Cells expressing the genes for granzyme A or TNF-α were seen in considerable numbers already on day 14, after adoptive transfer. These numbers gradually increased in the intra-islet infiltrates from day 14 through day 30 after adoptive transfer. Compared with our previous findings in NOD mice developing spontaneous insulin-dependent diabetes mellitus (IDDM) (Held W, MacDonald HR, Weissman IL, Hess MW, Mueller C: Genes encoding tumor necrosis factor α and granzyme A are expressed during development of autoimmune diabetes. Proc Natl Acad Sci USA 87:2239–xs2243, 1990), frequencies of cells with TNF-α and granzyme A mRNA were 2- and 12-fold higher, respectively, in transferred IDDM (trIDDM). TNF-α mRNA positive cells were predominantly found in the CD4+ T-cell subset of the pancreas-infiltrating cells, whereas granzyme A mRNA positive cells were mainly observed in the CD4− T-cell subset. The effects of the observed enhanced TNF expression upon the pathogenesis of trIDDM are as yet unknown. One may speculate, however, that a local production of TNF -αexerts direct cytotoxicity upon β-cells and promotes lymphocyte traffic to the pancreatic islets, thus resulting in an increased frequency of antigen-specific cytotoxic cells (mainly CD8+ T-cells) within the islets of Langerhans. The burst of activated granzyme A gene-expressing cells at the onset of diabetes further suggests that enhanced cell-mediated cytotoxicity may significantly contribute to the accelerated loss of β-cells.
The HOXD8 Locus (2q31) is Linked to Type I Diabetes: Interaction with Chromosome 6 and 11 Disease Susceptibility Genes
Authors: Owerbach David , Gabbay Kenneth H
Published: September 2013

Type I diabetes susceptibility genes have been identified within the major histocompatibility complex (MHC) on chromosome 6p21.3 and near the VNTR/insulin region on chromosome 11p15.5. We have used polymorphic dinucleotide repeat markers to search the human genome for additional susceptibility genes in 162 type I diabetic families with an affected sibling pair. We report that an additional susceptibility gene is located on chromosome 2q31 near HOXD8 (P < 10−5, maximum logarithm of odds score = 4.8) in an analysis of affected sibling pairs having specific human leukocyte antigen (HLA) and hypervariable nucleotide tandem repeat (VNTR)/insulin gene haplotypes (absence of high-risk HLA-DR3/4 haplotypes and presence of homozygous high-risk class I VNTR alleles). These results suggest the interaction of a minimum of three genes in the pathogenesis of type I diabetes in humans.
A Role for DNA Mutations in Diabetes-Associated Teratogenesis in Transgenic Embryos
Authors: Lee Annette T , Plump Andrew , DeSimone Christine , Cerami Anthony , Bucala Richard
Published: September 2013

Congenital malformations are the leading cause of death in infants of insulin-dependent diabetic mothers. Although there are data to suggest that hyperglycemia itself is teratogenic, few mechanisms have been proposed to explain diabetic embryopathy. To address the possibility that DNA mutations play a role in the fetal malformations associated with diabetes, we developed a transgenic mouse model system to measure the mutation frequency of a neutral target gene, lacI, during embryonic development in a maternal hyperglycemic environment. Despite the short 21-day gestational period of the mouse, we observed a twofold increase in the mutant frequency of the lacI transgene in fetuses that developed in a mild diabetic environment (blood glucose > 8.3 mmol/l) compared with those that developed under normoglycemic conditions (blood glucose < 8.3 mmol/l). These data provide the first direct evidence of the genotoxic effect of diabetes in vivo and suggest a mechanism for the teratogenicity of the maternal diabetic environment.
Reduced Expression of Hexokinase II in Insulin-Resistant Diabetes
Authors: Braithwaite Susan S , Palazuk Barbara , Colca Jerry R , Edwards Charles W , Hofmann Cecilia
Published: September 2013

The regulation of hexokinase II (HKII) was examined in fat and skeletal muscle of an animal model of non-insulin-dependent diabetes mellitus, the KKAY mouse. These tissues require insulin for facilitated transport of glucose and express the insulin-responsive transporter GLUT4. The combined data from two experiments (n = 12 for each experimental condition) demonstrated mean concentrations of plasma insulin in pmol/l and glucose in mmol/l of 122 and 7.2 (control nondiabetic C57 mouse) vs. 1,118 and 29.6 (diabetic mouse), respectively. The tissues of diabetic mice compared with control mice demonstrated a reduction of HKII mRNA abundance of 68% in epididymal fat (P = 0.0001) and 34% in the quadriceps muscles (P < 0.001), with concordant reduction in the abundance of GLUT4 mRNA of 60% in epididymal fat (P < 0.001). In comparison with the results in untreated diabetic mice, diabetic animals treated with the insulin-sensitizing drug pioglitazone demonstrated an increase in the abundance of HKII mRNA with a concordant increase of GLUT4 mRNA in epididymal fat (P = 0.03 and < 0.01, respectively), and an increase of HKII mRNA in the quadriceps muscles (P < 0.05). Separate experiments demonstrated a reduction of HKII protein abundance by 61% in epididymal fat (P < 0.001, n = 12 for each experimental condition) and by 71% in the quadriceps muscles (P < 0.001, n = 6 for each experimental condition). In comparison with untreated diabetic mice, there was an increase in the abundance of HKII protein in epididymal fat of animals treated with pioglitazone (P < 0.05). Additional experiments showed a reduction of HKII protein activity in untreated diabetic mice of 24% in the quadriceps muscles (P < 0.05, n = 6 for each experimental condition). Because HKII deficits can be reversed, it appears that abnormal expression of HKII may occur secondary to insulin resistance; nevertheless such changes may exacerbate hyperglycemia.
Loss of glucose-induced insulin secretion and GLUT2 expression in transplanted β-cells
Authors: Ogawa Yoshiji , Noma Yoshihiko , Davalli Alberto M , Wu Ying-Jian , Thorens Bernard , Bonner-Weir Susan , Weir Gordon C
Published: September 2013

Either 200 or 400 syngeneic islets were transplanted under the kidney capsule of normal or streptozocin-induced diabetic B6/AF1 mice. The diabetic mice with 400 islets became normoglycemic, but those with 200 islets, an insufficient number, were still diabetic after the transplantation (Tx). Two weeks after Tx, GLUT2 expression in the islet grafts was evaluated by immunofluorescence and Western blots, and graft function was examined by perfusion of the graft-bearing kidney. Immunofluorescence for GLUT2 was dramatically reduced in the β-cells of grafts with 200 islets exposed to hyperglycemia. However, it was plentiful in grafts with 400 islets in a normoglycemic environment. Densitometric analysis of Western blots on graft homogenates demonstrated that GLUT2 protein levels in the islets, when exposed to chronic hyperglycemia for 2 weeks, were decreased to 16% of those of normal recipients. Moreover, these grafts had defective glucose-induced insulin secretion, while the effects of arginine were preserved. We conclude that GLUT2 expression in normal β-cells is promptly down-regulated during exposure to hyperglycemia and may contribute to the loss of glucose-induced secretion of diabetes.
Skeletal Muscle Mitogen-Activated Protein Kinases and Ribosomal S6 Kinases: Suppression in Chronic Diabetic Rats and Reversal by Vanadium
Authors: Hei Yong-jiang , Chen Xunsheng , Pelech Steven L , Diamond Jack , McNeill John H
Published: September 2013

The mitogen-activated protein (MAP) kinases and ribosomal S6 protein kinases in the skeletal muscle of insulin-resistant long-term (2 and 6 months' duration) diabetic rats were investigated to understand further the changes in insulin intracellular signaling pathways that accompany diabetes. The effects of insulin-mimetic vanadium compounds on the activity of these kinases were also examined. In the insulin-resistant 2-month diabetic rats, the basal activities of MAP kinases were relatively unchanged, while the basal activities of S6 kinases were significantly increased. Intravenous injection of insulin moderately activated both the 42-kDa MAP kinase (p42mapk) and a 44-kDa MAP kinase (p44erk1) in the 2-month control rats but not in the 2-month diabetic rats. Insulin treatment markedly stimulated the activity of a novel 31-kDa S6 kinase and the previously described 90-kDa ribosomal S6 kinase encoded by one of the rsk genes (p90rsk) in the 2-month control rats, while the effect was substantially reduced in the diabetic rats. In the 6-month diabetic rats, the basal phosphotransferase activities of both MAP kinases were depressed threefold or greater. This correlated with reductions in the amount of immunoreactive p42mapk and p44erk1 proteins in extracts from the diabetic rats. The basal activity of the 31-kDa S6 kinase activity was also reduced fourfold in the 6-month diabetic rats. Treatment of the 2-month diabetic rats with vanadyl sulfate resulted in euglycemia, prevented the increase in the basal activity of S6 kinase, and improved the activation of S6 kinase by insulin. Treatment of the 6-month diabetic rats with an organic vanadium compound, bis(maltolato)oxovanadium(IV), also produced euglycemia and a restoration of the basal S6 kinase activities in these rats. The present findings indicate that insulin resistance associated with long-term diabetes may be linked with depressed signaling through these kinases and that this can be rectified by vanadium-containing compounds.
Contribution of Blood Flow to Leg Glucose Uptake During a Mixed Meal
Authors: Mijares Antonio Hernández , Jensen Michael D
Published: September 2013

Insulin has important effects to increase skeletal muscle (leg) blood flow under euglycemic hyperinsulinemic clamp conditions and after oral glucose tolerance testing. The present studies examined the effects of mixed meal consumption on the components of leg glucose uptake (LGU) in lean, healthy adults. Seventeen men and women underwent measures of leg plasma flow and arteriovenous (AV) glucose difference before and for 6 h after a mixed meal providing one-third of daily energy expenditure. Another eight men and women underwent the same studies before and during the consumption of the same-size meal administered in small frequent feedings over 6 h. After the bolus meal, peak leg AV glucose gradient increased ∼ fivefold (P < 0.001), whereas the peak increase in leg plasma flow was 20% (NS). No significant contribution of increased leg blood flow to the increase in postprandial LGU was apparent. Over the last 100 min of the frequent-feedings meal, the leg AV difference increased ∼ fourfold (P < 0.001 vs. basal), whereas leg blood flow increased only by 16% (NS vs. basal). We conclude that after a mixed meal, leg (primarily skeletal muscle) blood flow does not increase enough for blood flow to be a major contributor to glucose uptake. These findings raise questions regarding the relative importance of insulin's hemodynamic effects in modulating glucose tolerance under more usual conditions.
Role of Phosphodiesterase III in the Antilipolytic Effect of Insulin in Vivo
Authors: Hagström-Toft Eva , Bolinder Jan , Eriksson Sverker , Arner Peter
Published: September 2013

The effect of three types of phosphodiesterase (PDE) inhibitors on in vivo antilipolysis was investigated in healthy subjects using a 2-h euglycemic, hyperinsulinemic (40 mU · m-2·min) clamp together with microdialysis of abdominal subcutaneous adipose tissue. During hyperinsulinemia (∼330 pmol/l), the circulating glycerol concentration was reduced to ∼50% of the basal level of 53.2 ± 3.6 μmol/l, indicating an antilipolytic effect. The decrease in adipose tissue dialysate glycerol, which mirrors the change in interstitial glycerol concentration, was about 40% during hyperinsulinemia when Ringer's solution alone was perfused. Local perfusion with a selective PDE IV inhibitor, rolipram (10−4) mol/l), did not influence the insulin-induced decrease in dialysate glycerol (F = 0.8 vs. perfusion with Ringer's solution by two-factor analysis of variance [ANOVA]), although rolipram increased the dialysate glycerol level by 144 ± 7% of the baseline value. However, local perfusion with a selective PDE III inhibitor, amrinone (10−3) mol/l), or a nonselective PDE inhibitor, theophylline (10−2) mol/l), abolished the ability of insulin to lower dialysate glycerol (F = 16.5, P < 0.01 and F = 8.5, P < 0.01, respectively, as compared with perfusion with Ringer's solution). The findings could not be explained by changes in the local blood flow (as measured by a microdialysis–ethanol escape technique), which was not affected by hyperinsulinemia in the presence or the absence of PDE inhibitors in the dialysis solvent. We conclude that PDEs play an important role in mediating the antilipolytic effect of insulin in vivo and that PDE III is the dominant isoenzyme modulating this effect.
Late Progression to Diabetes and Evidence for Chronic β-Cell Autoimmunity in Identical Twins of Patients With Type I Diabetes
Authors: Verge Charles F , Gianani Roberto , Yu Liping , Pietropaolo Massimo , Smith Theresa , Jackson Richard A , Soeldner J Stuart , Eisenbarth George S
Published: September 2013

Previous studies suggest that after 6 years of discordance, identical twin pairs rarely become concordant for type I diabetes. With up to 39 years of follow-up from the onset of diabetes in the index twin, we determined how many discordant twins have evidence of β-cell autoimmunity and how many develop overt diabetes. We longitudinally followed 23 pairs of identical twins (or triplets) that were selected from a total group of 30 pairs because they were discordant for type I diabetes when first ascertained. Seven developed diabetes after 3, 3, 7, 8, 9, 31 and 36 years of discordance. By survival analysis, the concordance after 10 years from the onset of diabetes in the index twin was estimated as 23% (95% confidence interval, 5–40%), increasing to 38% (95% confidence interval, 8–69%) after 31 years. Among 16 twins remaining nondiabetic at last follow-up (8–39 years of discordance), 12 were assessed with serial intravenous glucose tolerance tests and a total of 407 measurements by radioassay of antibodies against three defined autoantigens (glutamic acid decarboxylase, insulin, and the recently cloned molecule ICA512). Two-thirds (8 of 12) had evidence of β-cell autoimmunity (persistently positive autoantibody levels) and/or first-phase insulin release < the 1st percentile of control subjects. In summary, identical twins may develop diabetes after a prolonged period of discordance and ∼ two-thirds of long-term discordant twins have evidence of persistent β-cell autoimmunity and/or β-cell damage. The concordance for β-cell autoimmunity, therefore, is much higher than for overt diabetes. This suggests that additional environmental or non-Mendelian genetic factors or time are required for the development of type I diabetes.
Treatment with Insulin-Like Growth Factor I Alters Capillary Permeability in Skin and Retina
Authors: Hussain Mehboob A , Studer Kilian , Messmer Elmar P , Froesch E Rudolf
Published: September 2013

Treatment with insulin-like growth factor I (IGF-I) is accompanied by mild generalized and reversible edema. These changes may be due to increased capillary permeability. Therefore, we studied the effects of subcutaneous IGF-I treatment in healthy subjects on capillary permeability of the skin and the retina. Eight healthy subjects were treated with saline or recombinant human IGF-I (rhIGF-I) (10 μg · kg−1 · h−1 s.c.) in a randomized crossover fashion. Transcapillary diffusion of sodium fluorescein (NaF) was quantitated by video densitometry in the skin in all subjects on the 4th treatment day. In seven subjects, plasma penetration of NaF at the blood-retinal barrier was investigated using vitreous fluorometry (VF) on days 3 and 5. Fluorescent light intensities of the skin and plasma penetration determined by VF were significantly higher during the IGF-I treatment as compared with those during the control situation. In conclusion, IGF-I treatment at the above dose is accompanied by increased transcapillary diffusion of NaF in skin and in retinal vessels.
Levels of Lipoprotein(a), Apolipoprotein B, and Lipoprotein Cholesterol Distribution in IDDM: Results From Follow-Up in the Diabetes Control and Complications Trial
Authors: Purnell Jonathan Q , Marcovina Santica M , Hokanson John E , Kennedy Hal , Cleary Patricia A , Steffes Michael W , Brunzell John D
Published: September 2013

Levels of lipoprotein(a) [Lp(a)], apolipoprotein (apo) B, and lipoprotein cholesterol distribution using density-gradient ultracentrifugation were measured as part of a cross-sectional study at the final follow-up examination (mean 6.2 years) in the Diabetes Control and Complications Trial. Compared with the subjects in the conventionally treated group (n = 680), those subjects receiving intensive diabetes therapy (n = 667) had a lower level of Lp(a) (Caucasian subjects only, median 10.7 vs 12.5 mg/dl, respectively; P = 0.03), lower apo B (mean 83 vs. 86 mg/dl, respectively; P = 0.01), and a more favorable distribution of cholesterol in the lipoprotein fractions as measured by density-gradient ultracentrifugation with less cholesterol in the very-low-density lipoprotein and the dense low-density lipoprotein fractions and greater cholesterol content of the more buoyant low-density lipoprotein. Compared with a nondiabetic Caucasian control group (n = 2,158), Lp(a) levels were not different in the intensive treatment group (median 9.6 vs. 10.7 mg/dl, respectively; NS) and higher in the conventional treatment group (9.6 vs. 12.5 mg/dl, respectively; P < 0.01). No effect of renal dysfunction as measured by increasing albuminuria or reduced creatinine clearance on Lp(a) levels could be demonstrated in the diabetic subjects. Prospective follow-up of these subjects will determine whether these favorable lipoprotein differences in the intensive treatment group persist and whether they influence the onset of atherosclerosis in insulin-dependent diabetes.
U.K. Prospective Diabetes Study 16: Overview of 6 Years' Therapy of Type II Diabetes: A Progressive Disease
Authors:   U.K. Prospective Diabetes Study Group
Published: September 2013

The objective of the U.K. Prospective Diabetes Study is to determine whether improved blood glucose control in type II diabetes will prevent the complications of diabetes and whether any specific therapy is advantageous or disadvantageous. The study will report in 1998, when the median duration from randomization will be 11 years. This report is on the efficacy of therapy over 6 years of follow-up and the overall incidence of diabetic complications. Subjects comprised 4,209 newly diagnosed type II diabetic patients who after 3 months' diet were asymptomatic and had fasting plasma glucose (FPG) 6.0–15.0 mmol/l. The study consists of a randomized controlled trial with two main comparisons: 1) 3,867 patients with 1,138 allocated to conventional therapy, primarily with diet, and 2,729 allocated to intensive therapy with additional sulfonylurea or insulin, which increase insulin supply, aiming for FPG <6 mmol/l; and 2) 753 obese patients with 411 allocated to conventional therapy and 342 allocated to intensive therapy with metformin, which enhances insulin sensitivity. In the first comparison, in 2,287 subjects studied for 6 years, intensive therapy with sulfonylurea and insulin similarly improved glucose control compared with conventional therapy, with median FPG at 1 year of 6.8 and 8.2 mmol/l, respectively (P < 0.0001). and median HbA1c of 6.1 and 6.8%, respectively (P < 0.0001). During the next 5 years, the FPG increased progressively on all therapies (P < 0.0001) with medians at 6 years in the conventional and intensive groups, FPG 9.5 and 7.8 mmol/l, and HbA1c 8.0 and 7.1%, respectively. The glycemic deterioration was associated with progressive loss of β-cell function. In the second comparison, in 548 obese subjects studied for 6 years, metformin improved glucose control similarly to intensive therapy with sulfonylurea or insulin. Metformin did not increase body weight or increase the incidence of hypoglycemia to the same extent as therapy with sulfonylurea or insulin. A high incidence of clinical complications occurred by 6-year follow-up. Of all subjects, 18.0% had suffered one or more diabetes-related clinical endpoints, with 12.1% having a macrovascular and 5.7% a microvascular endpoint. Sulfonylurea, metformin, and insulin therapies were similarly effective in improving glucose control compared with a policy of diet therapy. The study is examining whether the continued improved glucose control, obtained by intensive therapy compared with conventional therapy (median over 6 years HbA1c 6.6% compared with 7.4%), will be clinically advantageous in maintaining health.
Linkage Analysis of 19 Candidate Regions for Insulin Resistance in Familial NIDDM
Authors: Elbein Steven C , Chiu Ken C , Hoffman Michael D , Mayorga Rachel A , Bragg Kelli L , Leppert Mark F
Published: September 2013

As part of an ongoing search for diabetes susceptibility loci, we tested linkage with non-insulin-dependent diabetes mellitus (NIDDM) for 19 candidate loci or regions chosen for their potential to affect directly or indirectly the action of insulin. Loci were associated with insulin resistance, known effects on lipid metabolism, or effects on glucose metabolism or insulin action. Loci included the insulin-responsive (GLUT4) glucose transporter, hexokinase 2, glucagon, growth hormone, insulin receptor substrate 1 (IRS1), phosphoenolpyruvate carboxykinase, hepatic and muscle forms of pyruvate kinase, hepatic phosphofructokinase, the apolipoprotein B and the apolipoprotein A2 cluster, lipoprotein lipase, hepatic triglyceride lipase, the very-low-density-lipoprotein receptor, and the Pima insulin resistance locus on chromosome 4. For several candidates, no specific informative marker was available; consequently, we tested the surrounding region with highly informative markers. These regions included the diabetes-associated ras-like gene, rad, and the cholesterol ester–transfer gene, both mapped to chromosome 16. Additionally, we tested for linkage with markers at the tumor necrosis factor–α gene and the Friedreich's ataxia region. All regions were tested for linkage with microsatellite polymorphisms in >450 individuals from a minimum of 16 Caucasian families under parametric (LINKAGE 5.1) and nonparametric (affected pedigree member) models. On initial analysis, each region was rejected as a major diabetogenic locus under parametric models (logarithm of odds [LOD] <− 2) and nonparametric analyses, except growth hormone (LOD = 1.42; P < 0.005, nonparametric analysis) and IRS1 (P < 0.001, nonparametric analysis). Linkage of IRS1 and NIDDM was no longer significant when additional families were tested, and linkage of growth hormone under parametric analysis could likewise be rejected. However, under nonparametric, model-independent analysis, linkage to the growth hormone region remained suggestive. Additionally, possible evidence for linkage (P < 0.05) was found under nonparametric models for apolipoprotein A2 in an expanded sample of 29 families. We excluded multiple candidates as major diabetogenic loci, including fatty acid binding protein 2, IRS1, the insulin-responsive glucose transporter, and rad. However, the region around the growth hormone locus on chromosome 17 warrants further analysis in other populations.
Pancreatic Islet Cell Cytoplasmic Antibody in Diabetes is Represented by Antibodies to Islet Cell Antigen 512 and Glutamic Acid Decarboxylase
Authors: Myers Mark A , Rabin Daniel U , Rowley Merrill J
Published: September 2013

The presence of serum islet cell cytoplasmic antibodies (ICAs) is a standard autoimmune marker for insulin-dependent diabetes mellitus (IDDM). The antigenic molecule(s) responsible for ICA has not been identified, although antibodies to the 65-kDa isoform of glutamic acid decarboxylase (GAD65) do contribute. We tested 129 IDDM sera for antibodies to ICA512 (anti-ICA512), antibodies to GAD (anti-GAD), and ICAs; we tested for inhibition of ICAs with purified recombinant ICA512 and sheep brain GAD; and we tested for immunofluorescence reactivity on COS7 cells transfected with cDNA clones encoding ICA512 and GAD65. The results were that anti-ICA512 antibodies contribute to ICA reactivity and that these, in combination with anti-GAD antibodies, account for most ICA reactivity in IDDM. Anti-ICA512 antibodies were present at a frequency of 51% in 61 patients with early-onset IDDM (age of onset ≤20 years) of short duration (≤1 month) but only in 9% of 68 patients with an onset age of >20 years and/or a disease duration of >1 month. The frequency of anti-GAD antibodies in these sera was similar irrespective of duration or age of onset. Anti-ICA512 and anti-GAD antibodies were demonstrable by indirect immunofluorescence on transfected COS7 cells, and ICA could be inhibited using either recombinant ICA512 or purified brain GAD. We conclude that anti-ICA512 and anti-GAD antibodies contribute to ICA reactivity and that anti-ICA512 antibodies account for the increased frequency of ICA reactivity in early-onset IDDM of short duration.
Albuminuria and Poor Glycemic Control Predict Mortality in NIDDM
Authors: Gall Mari-Anne , Borch-Johnsen Knut , Hougaard Philip , Nielsen Flemming S , Parving Hans-Henrik
Published: September 2013

The impact of microalbuminuria and macroalbuminuria on mortality was evaluated prospectively in 328 Caucasian patients with non-insulin-dependent diabetes mellitus (NIDDM) followed for 5 years. One hundred ninety-one (109 men and 82 women) patients with normoalbuminuria (albumin excretion rate [AER] <30 mg/24 h), 86 (50 men and 36 women) patients with microalbuminuria (AER 30–299 mg/24 h), and 51 (43 men and 8 women) patients with macroalbuminuria (AER ≥300 mg/24 h) <66 years old at entry were followed from 1987 until death or until 1 January 1993. Mean age at entry was 54 (SD 9) years. In January 1993, 8% of patients with normoalbuminuria, 20% of patients with microalbuminuria, and 35% of patients with macroalbuminuria had died (predominantly from cardiovascular disease) (P <0.01 [normoalbuminuria versus micro- and macroalbuminuria] and P <0.05 [microalbuminuria versus macroalbuminuria]). Cox multiple regression analysis revealed significant predictors of all-cause mortality to be preexisting coronary heart disease (relative risk [95% confidence interval]), 2.9 (1.6–5.1); log10AER (factor 10), 1.9 (1.4–2.6); HbA1c level (%), 1.2 (1.0–1.4); and age (years), 1.08 (1.03–1.13). Significant predictors of cardiovascular mortality included preexisting coronary heart disease, 6.1 (2.8–13.5); macroalbuminuria, 2.5 (1.1–5.8); HbA1c level (%), 1.3 (1.1–1.6); and systolic blood pressure (10 mmHg), 1.2 (1.0–1.4). Univariate Cox survival analysis in the normoalbuminuric group revealed that AER above the median of 8 mg/24 h was associated with an increased all-cause mortality risk of 2.7 (0.93–7.69) (P = 0.07). We conclude that abnormally elevated urinary albumin excretion and poor glycemic control indicate a substantially increased allcause, mainly cardiovascular, mortality risk in NIDDM patients.
Elevation of Serum Insulin Concentration During Euglycemic Hyperinsulinemic Clamp Studies Leads to Similar Activation of Insulin Receptor Kinase in Skeletal Muscle of Subjects With and Without NIDDM
Authors: Klein Harald H , Vestergaard Henrik , Kotzke Gerd , Pedersen Oluf
Published: September 2013

The role of skeletal muscle insulin receptor kinase in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) was investigated. Muscle biopsies from 13 patients with NIDDM and 10 control subjects at fasting serum insulin concentrations and ∼1,000 pmol/l steady-state serum insulin during euglycemic hyperinsulinemic clamps were immediately frozen. The biopsies were then solubilized, and the receptors were immobilized to anti-insulin receptor antibody-coated microwells. Receptor kinase and binding activities were consecutively measured in these wells. The increase in serum insulin concentration (73 ± 14 to 1,004 ± 83 and 45 ± 7 to 1,070 ± 77 pmol/l in the NIDDM and control groups, respectively) had similar effects on receptor kinase activity in both study groups (12 ± 1 to 42 ± 5 and 12 ± 2 to 47 ± 5 amol P · fmol binding activity−1 · min−1 in the NIDDM and control groups, respectively). Moreover, by selecting only the receptors that bound to anti-phosphotyrosine antibody, we found similar hyperinsulinemia-induced increases of this receptor fraction and its kinase activity in both study groups. In vitro activation of the immobilized receptors with 2 mmol/l ATP and insulin further increased their kinase activity to almost similar levels, independently of whether they had been previously stimulated in vivo or were from diabetic or nondiabetic subjects. Compared with this activity reached in vitro, the kinase activity obtained by in vivo stimulation at the clamp insulin concentration was only ∼12%, because most receptors remained inactive and only a few reached almost the in vitro activation level. Our data suggest 1) that 1,000 pmol/1 serum insulin activates only a small fraction of insulin receptors in intact muscle and 2) that NIDDM is not associated with impaired insulin activation of insulin receptor kinase in skeletal muscle, at least not when euglycemia is maintained.
High-Glucose–Triggered Apoptosis in Cultured Endothelial Cells
Authors: Baumgartner-Parzer Sabina M , Wagner Ludwig , Pettermann Maria , Grillari Johannes , Gessl Alois , Waldhäusl Werner
Published: September 2013

High ambient glucose concentration, linked to vascular complications in diabetes in vivo, modulates mRNA expression of fibronectin, collagen, tissue-type plasminogen activator, and plasminogen activator inhibitor and induces delayed replication and excess cell death in cultured vascular endothelial cells. To determine the role of high ambient glucose (30 mmol/1) in apoptosis, paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs) were exposed to both high (30 mmol/1) and low (5 mmol/1) concentrations of glucose for short-term (24, 48, and 72 h) and long-term (13 ± 1 days) experiments. Incubation of HUVECs with high glucose for >48 h increased DNA fragmentation (13.7 ± 6.5% of total DNA, mean ± SD) versus cultures kept in 5 mmol/1 glucose (10.9 ± 5.6%, P < 0.005), as measured by [3H]thymidine assays. Data were confirmed by apoptosis-specific fluorescence-activated cell sorter analysis of confluent HUVEC cultures, which displayed after long-term exposure to 30 mmol/1 glucose a 1.5-fold higher prevalence of apoptosis than control cultures exposed to 5 mmol/1 glucose (P < 0.005). In contrast, no increase in DNA fragmentation in response to 30 mmol/1 glucose was seen for standardized cell lines (K 562, P 815, YT) and fibroblasts. Expression of clusterin mRNA, originally reported to be a molecular marker of apoptosis, was only slightly affected by short-term (24-h) high-glucose exposure but was significantly reduced after long-term incubation in 30 mmol/1 glucose (82.2 ± 13.8% of control) versus 5 mmol/1 glucose, which questions the role of clusterin gene expression as a marker of apoptosis. The results demonstrate that high ambient glucose can promote apoptosis in HUVECs in vitro and suggest potential endothelial damage by hyperglycemia in diabetic patients.
Pancreatic Islet GLUT2 Glucose Transporter mRNA and Protein Expression in Humans With and Without NIDDM
Authors: Ferrer Jorge , Benito Carmen , Gomis Ramon
Published: September 2013

GLUT2 glucose transporter mRNA has been shown to be underexpressed in pancreatic islets of numerous animal models of non-insulin-dependent diabetes mellitus (NIDDM). It has been proposed that this molecular defect contributes to the pathogenesis of diabetes, although information concerning the expression of GLUT2 in human pancreatic islet tissue is lacking. In contrast to the high abundance of GLUT2 in rat islets, human islets were found to express distinctly low levels of this glucose transporter mRNA and protein. Thus, a sensitive competitive reverse transcription-polymerase chain reaction assay was developed to quantify human GLUT2 mRNA. We obtained pancreases from 4 human organ donors with previously diagnosed NIDDM and 11 nondiabetic donors and found no significant differences in GLUT2 mRNA between the two groups. GLUT2 mRNA was 0.24 ± 0.08 amol/μg RNA (mean ± SE) in pancreases from humans with diabetes and 0.27 ± 0.06 amol/μg RNA in those without this diagnosis. Similarly, human pancreatic islet GLUT2 protein was measured by immunoblot and found to be present at similar levels in two individuals with diabetes relative to six control samples. These results thus demonstrate the existence of species differences in the abundance of islet GLUT2 mRNA and protein. Furthermore, the analysis of isletGLUT2 in a small sample of human organ donors with and without diabetes raises the possibility that decreased β-cell GLUT2 may not represent a widespread feature of humans with NIDDM.
NIDDM is the Major Cause of Diabetic End-Stage Renal Disease: More Evidence From a Tri-Ethnic Community
Authors: Pugh Jacqueline A , Medina Rolando A , Cornell John C , Basu Srabashi
Published: September 2013

Diabetes is the single largest cause of end-stage renal disease (ESRD) in adults in the U.S. Insulin-dependent diabetes mellitus (IDDM) has been recognized for some time as an important cause of ESRD, but non-insulin-dependent diabetes mellitus (NIDDM) has been assumed, until recently, to rarely cause ESRD. The objective of this study is to determine the incidence of treatment of diabetic ESRD by diabetic type for three ethnic/racial groups: non-Hispanic whites, African-Americans, and Mexican-Americans. A population-based incidence cohort was assembled from all dialysis centers in Bexar (San Antonio) and Dallas counties in Texas. All patients with diabetic ESRD beginning dialysis between 1 December 1987 (Bexar) or 1 December 1988 (Dallas) and 31 July 1991 were identified. All non-hispanic whites and African-Americans and a 1/2 random sample of Mexican-Americans were approached for enrollment. Individuals were confirmed to have diabetes using the World Health Organization criteria. Diabetes typing was done using a computerized historical algorithm. Age-specific and age-adjusted incidence rates were obtained by diabetic type and ethnic/racial group. NIDDM causes the majority of diabetic ESRD: 59.5% for non-Hispanic whites, 92.8% for Mexican-Americans, and 84.3% for African-Americans. Mexican-Americans and African-Americans, respectively, have 6.1 and 6.5 times higher incidence of treatment for diabetic ESRD than non-Hispanic whites. NIDDM results in more ESRD than does IDDM. Minorities (African-Americans and Mexican-Americans) are at increased risk, and programs aimed at prevention of NIDDM-related ESRD must focus on them.
Aberrant Activation of CD8+ T-cell and CD8+ T-Cell Subsets in Patients With Newly Diagnosed IDDM
Authors: Hehmke Bernd , Michaelis Dietrich , Gens Elke , Laube Frank , Kohnert Klaus-Dieter
Published: September 2013

Two- and three-color cytofluorimetric techniques were used to study the expression patterns of the activation antigen HLA-DR on peripheral blood immunoregulatory T-cells from 25 patients with newly diagnosed insulin-dependent diabetes mellitus (IDDM) and 14 age- and sex-matched control subjects. The mean percentage of total activated (CD3+HLA-DR+) T-cells was significantly elevated in the IDDM group compared with the control group (P < 0.001). In control subjects, basal activation of CD4+ and CD8+ lymphocytes accounted for the low percentage levels of activated T-cells. In contrast, the majority of IDDM patients showed an unbalanced activation of CD4+ and CD8+ lymphocytes with predominant activation of the CD8+ lymphocyte subset. The composition of the activated T-cell fraction was dependent on the composition of the total (activated + nonactivated) T-cell population, as indicated by the positive correlation between the CD4+/CD8+ T-cell ratios in these two cell populations (r = 0.714; P < 0.001). Excessive activation of CD8+ T-cells was attributable to similar increases in the proportions of CD8+CD45RA+HLA-DR+ (naive) and CD8+CD45RA−HLA-DR+ (memory) cells. Analysis of the CD11b-defined subsets revealed predominant activation of CD8+ CD11b− (cytotoxic) T-cells; CD8+CD16+ HLA-DR+ natural killer cells wereunchanged. The distribution of HLA-DR+ cells among subsets of CD4+ T-cells differed from the pattern in the CD8+ population in that selective activation of CD4+ CD45RA− (memory, helper-inducer) cells accounted for the small increase in activated CD4+ cells. The present findings suggest an important role for CD8+ T-lymphocytes in IDDM and raise the possibility that these lymphocytes might be the relevant target for early immunotherapy in patients with recent disease onset.
Regulation of Hexokinase II Gene Transcription and Glucose Phosphorylation by Catecholamines, Cyclic AMP, and Insulin
Authors: Osawa Haruhiko , Printz Richard L , Whitesell Richard R , Granner Daryl K
Published: September 2013

The hexokinases, by converting glucose to glucose-6-phosphate, help maintain the downhill gradient that results in movement of glucose into cells through the facilitative glucose transporters. GLUT4 and hexokinase (HK) II are the major transporter and hexokinase isoforms in skeletal muscle,heart, and adipose tissue, wherein insulin promotes glucose utilization. To understand whether hormones influence the contribution of phosphorylation to cellular glucose utilization, we investigated the effects that catecholamines, cyclic AMP (cAMP), and insulin have on HKII gene expression incells representative of muscle (L6 cells) and brown (BFC-1B cells) and white (3T3-F442A cells) adipose tissues. Isoproterenol or the cAMP analog 8-chlorophenylthio-cAMP selectively increase HKII gene transcription in L6 cells, as does insulin (Printz RL, Koch S, Potter LP, O'Doherty RM,Tiesinga JJ, Moritz S, Granner DK: Hexokinase II mRNA and gene structure, regulation by insulin, and evolution. J Biol Chem 268:5209–5219, 1993), and cause a concentration- and time-dependent increase of HKII mRNA in both muscle and fat cell lines without changing HKI mRNA. Isoproterenol and insulin also increase the rate of synthesis of HKII protein and increase glucose phosphorylation and glucose utilization in L6 cells.
The ob Gene and Insulin: A Relationship Leading to Clues to the Understanding of Obesity
Authors: Cusin Isabelle , Sainsbury Amanda , Doyle Patrick , Rohner-Jeanrenaud Françoise , Jeanrenaud Bernard
Published: September 2013

Obesity and non-insulin-dependent diabetes are estimated to affect millions of people in the world. This pathology is multifactorial, comprising complex interactions of genetic and environmental factors and lacking a specific therapy. Great interest arose from the recent discovery of the ob gene expressed only in adipose tissue and coding for a protein that appears to regulate adiposity, potentially by acting as a satiety factor. We report here that in normal rats, ob mRNA is respectively up- or downregulated by a rise in insulinemia (induced by 2-day insulin infusion while maintaining euglycemia) or a decrease in insulinemia (induced by a 3-day fast). Our results also show that in genetically obese fa/fa rats studied longitudinally, white adipose tissue ob mRNA levels increase in parallel with early occurringand steadily increasing hyperinsulinemia. This results in adult obese animals having markedly higher ob mRNA levels than age-matched normoinsulinemic lean rats. Furthermore, in adult obese rats, ob mRNA escapes down-regulation as normalization of hyperinsulinemia due to fasting fails to reduce the high ob mRNA levels.
Palmitate-Induced β-Cell Insensitivity to Glucose is Coupled to Decreased Pyruvate Dehydrogenase Activity and Enhanced Kinase Activity in Rat Pancreatic Islets
Authors: Zhou Yun-Ping , Grill Valdemar E
Published: September 2013

We previously found that long-term exposure to fatty acids impairs glucose-induced insulin release. In the present study, we investigated whether impairment is related to decreased pyruvate dehydrogenase (PDH) and increased PDH kinase activity. Rat pancreatic islets were cultured for 48 h in RPMI-1640 medium with or without 0.125 mmol/l palmitate. Potentiation of insulin responses to succinic acid monomethylester (SAM) by 10 mmol/l acetate and pyruvate were subsequently compared in order to assess whether generation of acetyl-coenzyme A (CoA) from pyruvate was deficient in the intact β-cell. Potentiation by acetate was similar in control and palmitate-preexposed islets. In contrast, pyruvate potentiated SAM-induced response by 122% in control but by only 39% in palmitate-exposed islets (P < 0.001). In extracts of palmitate-exposed islets, the active (unphosphorylated) form of PDH was decreased by 50% and total PDH activity (assessed after phosphatase treatment) by 25%. The proportion of active form to total PDH activity was also reduced (42.7 ± 2.6% after palmitate vs. 66.6 ± 4.3% in control islets, P < 0.01). In the same preparations, PDH kinase activity was enhanced 1.7-fold by palmitate in terms of the rate constant of ATP-dependent inactivation of PDH (P < 0.05). To test for a role of free (not PDH-bound) kinase, a PDH-free mitochondrial fraction was prepared, and its kinase activity was tested against a pig heart PDH preparation. Free kinase activity was increased 1.9-fold in palmitate-treated islets (P < 0.01). In conclusion, long-term exposure to fatty acids limits the conversion of pyruvate to acetyl-CoA through inhibition of PDH activity, which is linked to increased activity of a non-PDH-bound kinase. These findings could have relevance for deficient insulin release in type II diabetes.