bluuebunny/crossref_metadata_2025 huggingface dataset:
Independent Effects of Youth and Poor Diabetes Control on Responses to Hypoglycemia in Children
Authors: Jones Timothy W , Boulware Susan D , Kraemer Deborth T , Caprio Sonis , Sherwin Rrobert S , Tamborlane William V
Published: September 2013

To evaluate the effects of childhood and poorly controlled insulin-dependent diabetes mellitus (IDDM) on counterregulatory hormone and symptomatic responses to hypoglycemia, we studied 16 nondiabetic children (13 ± 2 yr), 19 nondiabetic adults (26 ± 3 yr), and 13 children with IDDM (14 ± 2 yr, HbA1, 15.1 ± 3.3%) during a gradual reduction in plasma glucose with the glucose-clamp technique. Plasma glucose was reduced from ∼5 to ∼2.8 mM over 240 min with serial assessment of counterregulatory hormone levels and symptom awareness. The plasma glucose level that triggered a sustained rise in plasma epinephrine was consistently higher in nondiabetic children than in adults (3.9 ± 0.06 vs. 3.2 ± 0.06 mM, P < 0.001). Poorly controlled IDDM further elevated the glucose threshold for epinephrine release to normoglycemic levels (4.9 ± 0.2 mM, P < 0.001 vs. both control groups). Age and IDDM also produced an upward shift in the glucose level at which growth hormone release and symptom awareness were initiated. In contrast to the effect on glucose thresholds, maximal epinephrine responses and symptom scores were increased only by age and not IDDM (2-fold higher in children). We conclude that childhood and poor diabetes control independently contribute to an upward shift in glucose thresholds for counterregulatory hormone release and symptom awareness during mild hypoglycemia. Normoglycemic counterregulation may interfere with efforts to control diabetes in young patients.
Hypoxemic Stimulation of Heart Glycogen Synthase and Synthesis: Effects of Insulin and Diabetes Mellitus
Authors: Laughlin Maren R , Morgan Cheryl , Barrett Eugene J
Published: September 2013

With radiotracer and 13C nuclear magnetic resonance (13C-NMR) methods, we studied the time course of glycogen resynthesis after three 90-s episodes of hypoxemia in both control and diabetic rats in vivo. Glycogen synthesis was measured in the presence and absence of infused insulin and compared with the changes in glycogen synthase (GS) and phosphorylase activities. We observed in 13C-NMR spectra the expected mobilization of glycogen during hypoxia in vivo. In control rats with or without exogenous insulin, this was followed by a rapid resynthesis of glycogen during a 40-min recovery period. A marked activation of GS was observed by 10 min (glucose-6-phosphate–independent form of GS [GSl] = 0.65 μmol · min−1 · g−1 or 92% of total GS), and activation persisted up to 40 min in both groups. Glycogen synthesis during the recovery period averaged 0.51 and 0.45 μmol · min−1 · g−1 in the saline- and insulin-treated rats, respectively. In the diabetic rats by 10 min after hypoxemia, GSl increased only modestly in both saline-treated (0.16 μmol · min−1· g−1) and insulin-treated (0.21 μmol · min−1 · g−1) rats, and activation persisted up to 40 min only with insulin treatment. Glycogen synthesis was slower in the diabetic rats given insulin (0.28 μmol · min−1 · g−1) and essentially absent in the saline-treated rats (0.03 μmol · min−1 · g−1) compared with controls. We conclude that recovery from hypoxemia is accompanied by a marked activation of GSl and rapid rates of glycogen synthesis in nondiabetic rats, and diabetes markedly blunts this response. Acute insulin infusion only partially overcomes this block. This impairment in glycogen storage may impact on the ability of the diabetic myocardium to withstand repeated hypoxemic or ischemic stresses.
T-Lymphocyte Requirement for Diabetes in RT6-Depleted Diabetes-Resistant BB rats
Authors: Woda Bruce A , Handler Eugene S , Greiner Dale L , Reynolds Craig , Mordes John P , Rossini Aldo A
Published: September 2013

Diabetes-prone (DP) BB rats develop spontaneous autoimmune insulin-dependent diabetes mellitus (IDDM). The cell populations involved in the expression of diabetes are not precisely known but probably include natural killer (NK) cells, macrophages, and T lymphocytes. Because the DP rat has few lymphocytes of the CD5+/CD+ phenotype, cytotoxic T lymphocytes (Tc) are not believed to be important in the process. Diabetes-resistant (DR) BB rats that are depleted of RT6+ T lymphocytes also become diabetic and provide an additional model of IDDM. We report that diabetes in DR rats depleted of RT6+ T lymphocytes is prevented by the concomitant depletion of either the CD5+ or the CD8+ population. In contrast, coadministration of anti-asialogangliosideM1 (α-ASGM1), an antiserum that principally recognizes NK cells, failed to prevent hyperglycemia in RT6-depleted rats. We propose that the initiation of diabetes in both DP and RT6-depleted DR rats is T-lymphocyte dependent. However, the final common pathway leading to autoimmune β-cell destruction in IDDM may be different in these models. The RT6-depleted DR rat requires a cell that is sensitive to anti-CD8 (possibly a Tc), whereas the DP rat requires an anti-ASGM1–sensitive cell.
Degradation of Intraendosomal Insulin by Insulin-Degrading Enzyme Without Acidification
Authors: Hamel Frederick G , Mahoney Michael J , Duckworth William C
Published: September 2013

The nature of insulin degradation within endosomes was studied in vitro. Radiolabeled insulin was perfused into rat liver via the portal vein, and insulin-containing endosomes were prepared by differential centrifugation. The endosomes were incubated in various buffers, and hormone degradation was monitored by Sephadex G-50 chromatography and high-performance liquid chromatography (HPLC). Endosomes incubated in simple imidazole or HEPES (pH 7.4) buffers rapidly degraded insulin to intermediate- and then to low-molecular-weight products that were lost from the vesicles. HPLC analysis of insulin-sized material showed the products to be the same as those produced by intact cells. The endosomes did not acidify in these buffers (as assessed by the acridine orange method), and ATP had no effects. When the endosomes were incubated in a chloride-containing buffer, degradation was greatly inhibited, and acidification did not occur. Both insulin degradation and acidification were activated when Mg-ATP was added to this buffer system. HPLC analysis of the products generated in this system revealed not only typical cellular products but additional less hydrophobic products. Western-blot analysis of endosomal protein with anti-insulin-degrading enzyme antibody showed this enzyme to be present. In conclusion, isolated endosomes rapidly and completely degrade insulin through products that are typical of cellular degradation without requiring acidification. Chloride-containing buffers inhibit endosomal degradation, which is reversed by Mg-ATP, but this system does not mimic cellular degradation. At least one of the enzymes responsible for insulin degradation is insulin-degrading enzyme.
Dysregulated Release and Degradation of Insulin During Mononuclear Cell–Induced β-Cell Lysis in HIT Cells
Authors: Robertson R Paul , Gromo Gianni , Zhang Hui-Jian , Walseth Timothy F , Inverardi Luca
Published: September 2013

Activated human mononuclear cells (MCs) were coincubated for 8 h with HIT cells, a clonal cell line of pancreatic islet β-cells. Measurements of HIT cell viability and insulin secretion were determined to 1) ascertain whether activated MCs can alter β-cells viability in the absence of exogenously provided cytokines, 2) examine this response over a range of MC–HIT cell ratios, and 3) identify mechanisms responsible for altered insulin release consequent to MC-induced HIT cell damage. HIT cell viability was markedly decreased by activated MCs during an 8-h coincubation. HIT cell lysis could be attributed to activated natural killer cells, and lysis did not occur in the presence of activated T-lymphocyte clones. Activated MCs caused a marked early increase in insulin release from HIT cells (increase at 2 h: 7.75 ± 0.16 nM for activated MCs, 2.66 ± 0.09 nM for control; P < 0.001). Insulin levels by the 8th h of the coincubation were significantly lower than the 2-h peak (4.33 ± 0.13 vs. 7.75 ± 0.16 nM, P < 0.001). These changes in insulin were dependent on the ratio of activated MCs to HIT cells with the effects clearly evident at an activated MC–HIT cell ratio of ≥ 10:1. Pretreatment of activated MCs and HIT cells with prostaglandin-synthesis inhibitors did not prevent the cytotoxic effects of activated MCs on HIT cells. Somatostatin did not inhibit the early exaggerated insulin release, suggesting that these increased insulin levels represented leakage of insulin from damaged HIT cells rather than functional insulin secretion. The decrements in insulin levels during the later stages of the experiments were determined by high-performance liquid chromatography to be caused by degradation of previously released insulin. These studies establish that activated MCs cause HIT cell lysis in the absence of exogenously provided cytokines and that HIT cells can be used as targets to examine the functional consequences of exposing pancreatic islet β-cells to activated MCs.
β-Cell Insensitivity to Glucose in the GK Rat, a Spontaneous Nonobese Model for Type II Diabetes
Authors: Portha Bernard , Serradas Patricia , Bailbé Danielle , Suzuki Ken-Ichi , Goto Yoshio , Giroix Marie-Hélène
Published: September 2013

In early 1988, a colony of GK rats was started in Paris with progenitors issued from F35 of the original colony reported by Goto and Kakisaki. When studied longitudinally up to 8 mo, GK rats showed as early as 1 mo (weaning) significantly higher basal plasma glucose (9 mM) and insulin levels (doubled), altered glucose tolerance (intravenous glucose), and a very poor insulin secretory response to glucose in vivo compared with Wistar controls. Males and females were similarly affected. Studies of in vitro pancreatic function were carried out with the isolated perfused pancreas preparation. Compared with nondiabetic Wistar rats, GK rats at 2 mo showed a significantly increased basal insulin release, no insulin response to 16 mM glucose, and hyperresponse to 19 mM arginine. Pancreatic insulin stores were only 50% of that in Wistar rats. Perfusion of GK pancreases for 50 or 90 min with buffer containing no glucose partially improved the insulin response to 16 mM glucose and markedly diminished the response to 19 mM arginine, whereas the responses by Wistar pancreases were unchanged. These findings are similar to those reported in rats with non-insulin-dependent diabetes induced by neonatal streptozocin administration and support the concept that chronic elevation in plasma glucose may be responsible, at least in part, for the β-cell desensitization to glucose in this model. The GK rat seems to be a valuable model for identifying the etiology of β-cell desensitization to glucose.
Reduction of Glomerular Hyperfiltration in Normoalbuminuric IDDM Patients by 6 mo of Aldose Reductase Inhibition
Authors: Pedersen Margrethe Mau , Christiansen Jens S , Mogensen Carl Erik
Published: September 2013

Hyperglycemia causes enhanced glucose metabolism by the polyol pathway in tissues not requiring insulin for glucose uptake. It has been suggested that the high level of aldose reductase activity may cause functional and structural abnormalities in diabetes and may be involved in the development of late complications. To elucidate the effect of an aldose reductase inhibitor (ponalrestat) on kidney function in uncomplicated insulin-dependent diabetes mellitus (IDDM), 20 normoalbuminuric IDDM patients were randomized to follow either 6 mo of treatment with ponalrestat (n = 11, mean ± SD age 30 ± 8 yr, diabetes duration 10 ± 6 yr) or 6 mo of placebo (age 33 ± 7 yr, diabetes duration 12 ± 6 yr). The glomerular filtration rate (clearance of [125I]iothalamate) was significantly reduced from 140 ± 18 to 129 ± 10 ml · min−1 · 1.73 m−2, 2P = 0.02) in the ponalrestat-treated patients, whereas no change was seen after placebo (142 ± 12 vs. 141 ± 12 ml · min−1 · 1.73 m−1). The renal plasma flow (clearance of 131I-labeled hippuran), urinary albumin excretion rate (radioimmunoassay), fractional albumin clearance, and renal vascular resistance were unchanged in both groups. HbA1c showed a modest increase during ponalrestat (7.9 ± 1.8 vs. 8.7 ± 1.5%, 2P = 0.01) but was unchanged during placebo. No side effects of ponalrestat were observed. Thus, inhibition of aldose reductase may reduce the characteristic hyperfiltration in uncomplicated IDDM.
Essential Fatty Acid Diet Supplementation: Effects on Peripheral Nerve and Skeletal Muscle Function and Capillarization in Streptozocin-Induced Diabetic Rats
Authors: Cameron Norman E , Cotter Mary A , Robertson Sharon
Published: September 2013

Effects of essential fatty acids on nerve conduction, hypoxic resistance, skeletal muscle contractile properties, and capillary density were examined in streptozocin-induced diabetic rats. Nondiabetic and diabetic controls and three diabetic groups treated with 10% supplements of corn oil, evening primrose oil (Efamol), or a mixture of 80% evening primrose oil and 20% fish oil (Efamol Marine) for 2 mo were used. Efamol and Efamol Marine increased plasma γ-linolenic acid levels, but arachidonic acid was elevated only with Efamol. Diabetes resulted in 15–29% reductions in sciatic motor and sensory saphenous nerve conduction velocity. Efamol prevented conduction deficits more effectively than Efamol Marine, and corn oil had no effect. In vitro measurement of sciatic nerve hypoxic resistance revealed a 49% increase in the time taken for action potential amplitude to decline by 50% with diabetes. Corn oil had no significant effect. With Efamol, hypoxic resistance was within the nondiabetic range. Efamol Marine produced intermediate results. Functional improvements may relate to enhanced vasa nervorum perfusion, because endoneurial capillary density increased by 22% with Efamol, angiogenesis perhaps resulting from eicosanoid production from arachidonic acid. Soleus muscle contractions were prolonged by diabetes. This was partially corrected by treatment, Efamol being most effective. Extensor digitorum longus muscle had reduced tetanic tension with diabetes, and this was prevented by all treatments. Soleus showed a modest increase in capillarization with Efamol, which may have contributed to reduced susceptibility to fatigue. The data suggest involvement of abnormal fatty acid metabolism in the etiology of diabetic neuropathy and myopathy.
Normalization of Na+-K+-ATPase Activity in Isolated Membrane Fraction From Sciatic Nerves of Streptozocin-Induced Diabetic Rats by Dietary myo-Inositol Supplementation in Vivo or Protein Kinase C Agonists in Vitro
Authors: Kim Jean , Kyriazi Harold , Greene Douglas A
Published: September 2013

A myo-inositol–related defect in nerve Na+-K+-ATPase in experimental diabetes has been invoked in the pathogenesis of diabetic neuropathy, but the mechanism linking altered myo-inositol metabolism and Na+-K+-ATPase regulation in diabetic nerve is uncertain. Decreased Na+-K+-ATPase in diabetic rat nerve is normalized by aldose reductase inhibitors or dietary myo-inositol, which preserve normal nerve myo-inositol content in vivo. Decreased Na+-K+-ATPase in diabetic rabbit nerve is acutely reversed by exposure to protein kinase C agonists in vitro. This study explored the relationship between the myo-inositol–sensitive and protein kinase C–agonist–sensitive Na+-K+-ATPase defects in diabetic rat nerve. Ouabain-sensitive ATPase activity was measured in an enriched membrane fraction isolated from nondiabetic, streptozocin-induced diabetic, and myo-inositol–supplemented streptozocin-induced diabetic rats before and after the membranes were exposed to protein kinase C agonists in vitro. The decreased ouabain-sensitive ATPase activity in plasma membranes from untreated diabetic rats was increased after exposure to two structurally unrelated protein kinase C agonists; the normal ouabain-sensitive ATPase in plasma membranes from myo-inositol–supplemented diabetic rats was unaffected by protein kinase C agonists. The nonadditivity and implied equivalence of the Na+-K+-ATPase defect corrected by myo-inositol in vivo and by protein kinase C agonists in vitro are consistent with the postulated existence of a deficient myo-inositol–dependent phospholipid-derived protein kinase C agonist (presumably diacylglycerol) in diabetic nerve that regulates nerve Na+-K+-ATPase either directly or via a protein kinase C mechanism.
Metabolic Effects of Fish-Oil Supplementation in Patients With Impaired Glucose Tolerance
Authors: Fasching Peter , Ratheiser Klaus , Waldhäusl Werner , Rohac Madeleine , Osterrode Wolf , Nowotny Peter , Vierhapper Heinrich
Published: September 2013

To determine the impact of fish-oil supplementation on glucose and lipid metabolism in patients with impaired glucose tolerance (IGT), 30 ml fish oil containing 3.8 g eicosapentaenoic acid (EPA; 20:5 ω 3) and 2.5 g docosahexaenoic acid (DHA; 22:5 ω 3) were given to eight obese subjects with IGT (mean ± SD age 50.3 ± 8.0 yr) in addition to their regular diet for 2 wk. Studies were performed in randomized order versus an isocaloric control period with a washout phase of 3 wk. Hyperinsulinemic clamp examinations (1 and 10 mU · kg−1 · min−1) were performed. Glucose disposal rate (M value) rose from basal 14.3 ± 5.1 to 17.9 ± 4.4 μmol · kg−1 · min−1 after fish oil (P < 0.001) during the 1-mU clamp, whereas no change was seen during the 10-mU clamp (without fish oil, 42.2 ± 8.9 μmol · kg−1 · min−1; with fish oil, 45.1 ± 9.8 μmol · kg−1 · min−1;NS). Basal hepatic glucose output remained unaffected by fish oil, whereas fractional glucose clearance after intravenous glucose loading (2.4 mmol/kg body wt, t = 30 min) tended to increase (K value: without fish oil, 2.15 ± 1.02%/min; with fish oil, 2.74 ± 1.26%/min; NS). Neither the fasting concentrations of glucose and insulin nor induced glycemia and insulin response during intravenous glucose loading calculated as incremental area under the curve changed after fish-oil supplementation. Supplementation of ω-3 fatty acids led to a mean decrease in total cholesterol of 15.2% (5.78 ± 1.19 to 4.90 ± 0.83 mM, P <0.02), low-density lipoprotein cholesterol of 20% (4.14 ± 1.00 to 3.36 ± 0.90 mM, P <0.02), apolipoprotein B concentration of 16% (1.25 ± 0.43 to 1.06 ± 0.30 g/L, P < 0.05), and total serum triglycerides of 41% (1.71 ± 0.79 to 1.02 ± 0.39 mM, P < 0.05). High-density lipoprotein cholesterol remained unchanged. Because whole-blood viscosity consistently fell, probably due to an increased erythrocyte deformability, the observed changes in lipid metabolism and blood rheology may also help reduce cardiovascular risk factors in subjects with IGT.
Effect of Zn2+ on the Proteolytic Inhibitory Action of Insulin and Biguanide Antihyperglycemic Drugs
Authors: Thorne David P , Lockwood Thomas D
Published: September 2013

The involvement of Zn2+ in the inhibitory action of insulin and phenformin on bulk proteolysis was studied in the Langendorff rat heart with a Zn(2+)-buffering perfusate (0.1 mM citrate, physiological complete amino acids and 0.2% albumin). Proteins were biosynthetically labeled in vitro for 10 min with [3H]leucine. Rapidly degraded proteins were eliminated during a 3-h preliminary degradation without insulin or added Zn2+ (2 mM nonradioactive leucine). Insulin (5 nM), the lysosomal inhibitor chloroquine (30 μM), and the biguanide antihyperglycemic agent phenformin (2 μm) each caused a sustained 35–40% inhibition of [3H]leucine release beginning within 1–2 min and reaching a maximum at 1–1.5 h. When these agents were combined, their simultaneous proteolytic inhibitory effects were not appreciably > the effect of chloroquine alone. Infusion of supraphysiological perfusate Zn2+ (>15 μM) mimicked the inhibitory effect of insulin and chloroquine on lysosomal proteolysis. Infusion of supraphysiological Co2+, Mn2+, Fe2+, and Cr3+ (30 μM, 0.5 h) caused no change in proteolysis; however, 30 μM Cu2+ caused a slight inhibition. Presumptive chelation of the background (∼20 nM) Zn2+ by infusion of 3 μM CaNa2 EDTA caused no change in protein degradation over 1–2 h. The infusion of a physiological concentration of 1 or 5 microM Zn2+ (as ZnCl2) caused no change in protein degradation over 1–2 h. Biguanides are known to reversibly form a Zn2+ complex with affinity < that of Zn2+ for EDTA. Prior infusion of 3 μM CaNa2 EDTA inactivated the proteolytic inhibitory effect of maximal (2 μM) phenformin over at least 1.25 h of concurrent infusion. restoration of physiological 2 μM Zn2+ immediately restored the insulin-mimetic proteolytic inhibitory action of phenformin under continued 3 μM CaNa2 EDTA (5 μM total Zn2+, 2 μM nonchelated Zn2+). The time course and potency of submaximal insulin (<0.1 nM) were decreased or increased by chelation of background perfusate Zn2+ (2 μM CaNa2 EDTA) or addition of 1 μM Zn2+, respectively. The action of maximal (5 μM) insulin was not changed by 5 IJLM CaNa2 EDTA or addition of 1 μM Zn2+. The proteolytic inhibition caused by maximal (5 nM) insulin was not reversed after 2 h of insulin discontinuation. However, 1 mM of the permeant dithiol Zn2+ chelator dimercaptopropane sulfonic acid largely reversed the proteolytic inhibition caused by maximal (5 nM) insulin.
Particular HLA-DQ αβ Heterodimer Associated With IDDM Susceptibility in Both DR4-DQw4 Japanese and DR4-DQw8/DRw8-DQw4 Whites
Authors: Rønningen Kjersti S , Gjertsen Henrik A , Iwe Thomas , Spurkland Anne , Hansen Torbjørn , Thorsby Erik
Published: September 2013

Insulin-dependent diabetes mellitus (IDDM) susceptibility is associated with the DR4-DQw4 haplotype in Japanese and the DR4-DQw8/-Drw8-DQw4 genotype (among others) in whites. We investigated whether these Japanese and white individuals encode the same or a similar DQ αβ heterodimer, which may be an IDDM-susceptibility molecule in both populations. First, we carried out genomic DQA1 and DQB1 typing with sequence-specific oligonucleotide probes. The results revealed that Japanese DR4-DQw4 and white DR4-DQw8/DRw8-DQw4 IDDM patients carried the DQA1*0301 allele and the DQB1*0401 or DQB1*0402 allele, either in the cis (Japanese DR4-DQw4 individuals) or trans (white DR4-DQw8/DRw8-DQw4 individuals) position. Because the DQB1*0401 and DQB1*0402 alleles differ only at residue 23, these DQB1 genes are very similar. We next tested cells from these individuals with a particular DQ-specific T-lymphocyte clone, HH58. The clone was only restimulated with cells from Japanese individuals who carried the DQA1*0301 and DQB1*0401 alleles in the cis position or white individuals who carried the DQA1*0301 and DQB1*0402 alleles in the trans position. Thus, particular cis- or trans-encoded DQ αβ heterodimers, which in both cases are recognized by T lymphocytes, may confer susceptibility to IDDM in both ethnic groups.
Detection of Mutations in Insulin-Receptor Gene in NIDDM Patients by Analysis of Single-Stranded Conformation Polymorphisms
Authors: O'Rahilly Stephen , Choi Woong H , Patel Pushpa , Turner Robert C , Flier Jeffrey S , Moller David E
Published: September 2013

We used the recently described technique of single-stranded conformation-polymorphism (SSCP) analysis to examine the insulin-receptor locus. First, the ability of the method to detect known mutations and polymorphisms in the insulin-receptor coding sequence was assessed. Regions of the insulin-receptor sequence containing 16 different nucleotide changes, 9 in patient genomic DNA and 7 as cloned cDNA in plasmids, were analyzed. All 9 patient genomic DNA mutants and 5 of 7 plasmid mutants exhibited variant SSCP patterns. To investigate the potential of the technique for screening many patients, the 5 exons that encode the tyrosine kinase domain of the insulin receptor were examined in 30 unrelated white subjects with non-insulin-dependent diabetes mellitus (NIDDM). Exons 17–21 were amplified from genomic DNA with polymerase chain reaction and subjected to SSCP analysis. Exons 19, 20, and 21 revealed no bands of aberrant migration, suggesting a high degree of conservation of these sequences. One diabetic subject had an SSCP variant in exon 18. Direct sequencing of this subject's genomic DNA revealed a heterozygous missense mutation (Lys1068 → Glu1068). Five different SSCP patterns were detected in exon 17. Based on direct sequencing, these patterns were explained by combinations of three different nucleotide substitutions, two of which were common silent polymorphisms. One subject had a heterozygous missense mutation Val985 → Met985. Allele-specific oligonucleotide hybridization confirmed the presence of these mutations in the appropriate diabetic subjects and also detected the Val985 mutation in heterozygous form in 1 of 13 nondiabetic white subjects. SSCP analysis is a sensitive rapid method for screening for mutations in the insulin-receptor gene. Using SSCP, we detected two previously unreported amino acid substitutions in the highly conserved tyrosine kinase domain of the insulin receptor. These represent the first potentially significant mutations found by screening candidate genes in NIDDM. The detection of one of these variants in a normoglycemic subject suggests that it is unlikely to cause the diabetic state, but given the complex genetic basis for NIDDM, a possible contributory role of each of these mutations mandates further study.
Risk Factors for NIDDM in White Population: Paris Prospective Study
Authors: Charles Marie A , Fontbonne Annick , Thibult Nadine , Warnet Jean-Michel , Rosselin Gabriel E , Eschwege Eveline
Published: September 2013

Risk factors for non-insulin-dependent diabetes mellitus (NIDDM) were assessed in a population of 5042 middle-aged white men, initially nondiabetic, who were followed 3 yr. The subjects were participants in the Paris Prospective Study I. Sixty-three subjects developed diabetes during the follow-up. Plasma glucose concentration in the years before the occurrence of the disease was a major risk factor. Subjects with normal glucose tolerance but elevated fasting plasma glucose exhibited a similar risk of developing NIDDM as did subjects classified as having impaired glucose tolerance on the basis of 2-h postload glucose. In a multiple logistic regression, a high fasting plasma insulin concentration and a low 2-h plasma insulin concentration after a glucose load in association with a high body mass index were independent predictors of conversion to NIDDM from impaired glucose tolerance. Previously, this result had been found only in Nauruans, Pima Indians, and Japanese. This demonstrates for the first time in a white population that a high fasting and low 2-h insulin concentration is predictive of conversion to NIDDM from impaired glucose tolerance.
1,2-Diacylglycerol Content and Its Fatty Acid Composition in Thoracic Aorta of Diabetic Rats
Authors: Okumura Kenji , Nishiura Takuja , Awaji Yoshifumi , Kondo Junichiro , Hashimoto Hidekazu , Ito Takayuki
Published: September 2013

These experiments were conducted to determine 1,2-diacylglycerol (DAG) in the thoracic aorta obtained from streptozocin-induced diabetic rats because 1,2-DAG is assumed to be a second messenger associated with phosphoinositide metabolism. After preincubation for a 25-min stabilization, 1,2-DAG content in isolated thoracic aortas 4 and 8 wk after streptozocin injection was significantly decreased by 42 and 31%, respectively, compared with age-matched control rats on 10-min norepinephrine stimulation (10−5 M). However, 4 wk of daily insulin injection after 4 wk of untreated diabetes significantly shifted 1,2-DAG toward normal levels. Analysis of its fatty acid composition showed a significant difference between control and diabetic rat aortas at both 4 and 8 wk. In particular, the percentage of arachidonate, a precursor of eicosanoids, decreased. Such alteration in the fatty acid profile in diabetic rat aortas was inhibited by insulin treatment. 1,2-DAG content in the 8-wk diabetic group was also significantly decreased by 33% compared with control in the absence of norepinephrine, whereas 1,2-DAG content was lower than in the presence of norepinephrine in both the control and diabetic groups. Cholesterol, triglyceride, and phosphatidylcholine content in diabetic rat aortas was lower than control. Lower levels of 1,2-DAG in the thoracic aorta from diabetic rats were observed in the presence and absence of norepinephrine, suggesting that a defect in 1,2-DAG production may be associated with abnormalities of vascular smooth muscle responsiveness by agonists, as described previously.
New Potent α-Glucohydrolase Inhibitor MDL 73945 With Long Duration of Action in Rats
Authors: Robinson Keith M , Begovic Mary E , Rhinehart Barry L , Heineke Eric W , Ducep Jean-Bernard , Kastner Philip R , Marshall Franklin N , Danzin Charles
Published: September 2013

Inhibition of intestinal α-glucohydrolase activity is one approach for reducing the glycemic response from dietary carbohydrate and may prove useful for the treatment of diabetes mellitus. In this article, we describe the pharmacological properties of a time-dependent intestinal α-glucohydrolase inhibitor, MDL 73945. When preincubated 2 h with a rat intestinal mucosa preparation before substrate addition, MDL 73945 was a potent inhibitor of sucrase, maltase, glucoamylase, and isomaltase activities (MDL 73945 concentrations required to cause a 50% decrease in enzyme activity, 2 × 10−7, 1 × 10−6, 5 × 10−6, and 8 × 10−6 M, respectively); without preincubation, it was 10- to 500-fold less potent. In rats, a single oral dose of MDL 73945 administered simultaneously with 2 g/kg body wt sucrose resulted in a dose-dependent reduction in the area under the 0- to 3-h glycemic response curve, which was significant at 1 (45% reduction) and 3 (65% reduction) mg/kg. When administered 1 h before sucrose, the compound was more potent, with 0.3 mg/kg MDL 73945 significantly reducing the glycemic response to sucrose by 62%. A reduction in the glycemic response to sucrose was accompanied by reduced insulin secretion. MDL 73945 was slightly less effective against a starch load, with 3 and 10 mg/kg MDL 73945 administered 0.5 h before starch reducing the glycemic response by 39 and 52%, respectively. MDL 73945 was more effective against a sucrose load in streptozocin-administered rats than in control rats and was as effective after 16 daily doses as after a single dose. Doses that reduced the glycemic response to carbohydrate did not inhibit liver lysosomal α-glucosidase activity or cause lysosomal glycogen accumulation. In cynomolgus monkeys, an oral dose of 1 mg/kg MDL 73945 reduced the glycemic and insulin responses to sucrose. Based on these findings, MDL 73945 may be useful for reducing postprandial hyperglycemia in subjects with diabetes mellitus.
Role for Autonomic Nervous System to Increase Pancreatic Glucagon Secretion During Marked Insulin-Induced Hypoglycemia in Dogs
Authors: Havel Peter J , Veith Richard C , Dunning Beth E , Taborsky Gerald J
Published: September 2013

To determine the role of the autonomic nervous system (ANS) in mediating the glucagon response to marked insulin-induced hypoglycemia in dogs, we measured arterial and pancreatic venous glucagon responses to insulin-induced hypoglycemia during acute, terminal experiments in halothane-anesthetized dogs in which the ANS was intact (control; n = 9), pharmacologically blocked by the nicotinic ganglionic antagonist hexamethonium (n = 6), or surgically ablated by cervical vagotomy and cervical spinal cord section (n = 6). In control dogs, insulin injection caused plasma glucose to fall by 4.4 ± 0.2 mM to a nadir of 1.7 ± 0.2 mM. Arterial epinephrine (EPI) levels increased by 13,980 ± 1860 pM (P < 0.005), confirming marked activation of the ANS. Pancreatic output of glucagon increased from 0.53 ± 0.12 to 2.04 ± 0.38 ng/min during hypoglycemia (change [Δ] + 1.51 ± 0.33 ng/min, P < 0.005). This increased arterial plasma glucagon from 27 ± 3 to 80 ± 15 ng/L (Δ + 52 ± 14 ng/L, P < 0.025). Hexamethonium markedly reduced the ANS response to insulin injection (ΔEPI + 2130 ± 600 pM, P < 0.025 vs. control) despite a similar fall of plasma glucose (Δ −4.1 ± 0.2 mM) and a lower nadir (0.6 ± 0.1 mM). Both the pancreatic glucagon response (delta glucagon output +0.45 ± 0.2 ng/min) and the arterial immunoreactive glucagon response (Δ + 5 ± 4 ng/L) were substantially reduced by hexamethonium (P < 0.025). Vagotomy plus spinal cord section totally abolished the arterial EPI response to insulin injection despite a larger fall of plasma glucose (Δ −5.4 ± 0.4 mM) and a lower nadir (0.9 ± 0.2 mM). Again, both the pancreatic glucagon response (Δglucagon output +0.27 ± 0.23 ng min) and the arterial glucagon response (Δ +5 ± 2 ng/L) were significantly reduced (both P < 0.025 vs. control). We conclude that autonomic activation contributes to the glucagon response to marked insulin-induced hypoglycemia in dogs.
Skeletal Malformations in Rat Offspring: Long-Term Effect of Maternal Insulin-Induced Hypoglycemia During Organogenesis
Authors: Tanigawa Keiichiro , Kawaguchi Mikiko , Tanaka Osamu , Kato Yuzuru
Published: September 2013

We studied the effect of maternal hypoglycemia on skeletal growth in the offspring of nondiabetic and diabetic rats. Female Wistar rats were injected with streptozocin (30 mg/kg i.v.) 2–3 wk before mating, and diabetes was confirmed by an intraperitoneal glucose tolerance test. On postconception day 9.5 or 10.5, both control and diabetic dams received saline or Actrapid human insulin (400 mU/rat i.p.). Hypoglycemia (∼2.8 mM) was induced for 120 min in the insulin-treated mothers. Pregnancy was terminated on gestational day 20. Fetal bones and cartilage were double-stained with alizarin red S and alcian blue 8GS. Insulin-induced hypoglycemia caused delayed ossification in the fetuses of the control dams. The number of malformations, e.g., costal fusion waves, increased greatly. These effects were more striking in the fetuses of dams that had received insulin on day 10.5 rather than on day 9.5 of embryo development. This type of insulin-induced hypoglycemia further delayed ossification of the fetal bones in diabetic dams. The influence of maternal hypoglycemia on skeletal malformations and/or variations was greater in the fetuses of diabetic dams than in the fetuses of control dams. These data suggest that maternal hypoglycemia in early pregnancy has a striking effect on skeletal growth and malformations in fetuses. In addition, mild glucose intolerance in dams may amplify these hypoglycemic effects.
HLA-Associated Insulin Autoantibody Formation in Newly Diagnosed Type I Diabetic Patients
Authors: Ziegler Anette G , Standl Eberhard , Albert Ekkehard , Mehnert Hellmut
Published: September 2013

To assess a possible HLA association with anti-insulin autoantibodies (IAAs) in human insulin-dependent (type I) diabetes, 51 newly diagnosed type I diabetic patients (mean age 22 ± 8 yr) were typed for HLA-DR and HLA-DQ and studied for IAAs before exogenous insulin therapy with a competitive radioimmunoassay (normal range ≤49 nU/ml). The level of IAAs in 16 patients exceeded our upper limit of normal, and 18 had high-titer islet cell antibodies (ICAs; ≥40 Juvenile Diabetes Foundation U). A striking association with HLA-DR4 (DQw3) in both the prevalence and the level of IAAs was found (IAA positivity in patients with DR4/4 vs. DR4 heterozygous vs. non-DR4: 90 vs. 29%, corrected [c] P < 0.01, vs. 5%, Pc < 0.0001; IAA positivity in patients with DR4 vs. non-DR4: 50 vs. 5%, Pc < 0.005; IAA level in patients with DR4/4 vs. DR4 heterozygous vs. non-DR4: 111 vs. 17 nU/ml, Pc < 0.01, vs. 20 nU/ml, Pc < 0.0001; IAA level in patients with DR4 vs. non-DR4: 45 vs. 20 nU/ml, Pc < 0.01). In contrast, none of the DR3+ subjects had IAAs above normal range, except in conjunction with DR4 (DR3 vs. non-DR3: 12 vs. 42%, Pc < 0.05). However, there was no significant relationship between DR3 and IAAs after correcting for the number of DR4 alleles. No relationship was seen between age of onset, IAA level, and HLA typing in our population, and no relationship was found between ICA positivity and HLA antigens. These data suggest that humoral in predominantlu DR4+ patients responding to insulin before exogenous insulin treatment.
Prevention of Cyclophosphamide-Induced and Spontaneous Diabetes in NOD/Shi/Kbe Mice by Anti-MHC Class I Kd Monoclonal Antibody
Authors: Taki Toshiya , Nagata Masao , Ogawa Wataru , Hatamori Nobuo , Hayakawa Michiko , Hari Joji , Shii Kozui , Baba Shigeaki , Yokono Koichi
Published: September 2013

The immune mechanisms directly responsible for β-cell destruction in insulin-dependent diabetes are undefined. We studied the role of MHC class I–restricted T lymphocytes in the development of diabetes in cyclophosphamide (CY)-treated male and untreated female NOD mice (H-2Kd,Db). After administration of CY to 10-wk-old male NOD/Shi/Kbe mice, 37 of 64 (58%) phosphate-buffered saline–injected control mice and 13 of 22 (59%) anti-Kb and 12 of 27 (44%) anti-Db monoclonal antibody (MoAb)-injected mice became diabetic by 14 wk of age, whereas only 3 of 38 (8%) anti-Kd and 2 of 13 (15%) anti-Lyt-2 MoAb-injected mice did. In untreated female NOD/Shi/Kbe mice, 30 of 46 (65%) mice developed spontaneous diabetes by 30 wk of age, whereas none of 9 anti-Kd MoAb-injected mice became diabetic. Immunohistochemical studies showed that islet-infiltrating cells in CY-treated control mice were composed mainly of both L3T4+ and Lyt-2+ T lymphocytes, whereas many L3T4+ and very few Lyt-2+ lymphocytes infiltrated within the islets in anti-Kd MoAb-injected mice. Administration of anti-Lyt-2 MoAb induced the absence of Lyt-2+ T lymphocytes in the islet and spleen. However, anti-Kd MoAb did not change the number of spleen cells or the T-lymphocyte subset and response to concanavalin A. These results suggest that MHC class I Kd-restricted Lyt-2+ T lymphocytes play an important role as direct effector cells in destruction of β-cells in NOD/Shi/Kbe mice.
Purification and Preliminary Characterization of New Peptide Inhibitor of Insulin From Pork Pancreas
Authors: Ma Jian-Nong , Zhu Bao-Lino , Chi Cheng-Wu
Published: September 2013

A new active peptide was purified from the acid-alcohol extract of pork pancreas. It markedly suppressed the insulin activity detected by either in vivo mouse convulsion assay or in vitro free–fat cell assay. When the extract was subjected to chromatography on a carboxymethylcellulose column, the insulin fraction completely passed through the column, whereas the glucagon fraction was absorbed. The fact that the total apparent biological activity of insulin in the exclusive eluate was higher than in the original extract and the insulin radioimmunoactivity remained unchanged led to the discovery of a potent insulin inhibitor in the extract. The inhibitor was separated from glucagon and insulin in the extract by ion-exchange chromatography on a carboxymethylcellulose column followed by gel filtration on a Bio-Gel P-6 column and finally purified by reverse-phase high-performance liquid chromatography (HPLC) on a C-18 column. The antagonistic effect of this inhibitor on insulin was dose dependent with an ED50 of 2 × 10−10 M, which was the same level used for insulin in vitro assay (1.7 × 10−10 M). Amino acid analysis of the inhibitor showed that it was rich in arginine and glycine. It was estimated to be ∼3000 Mr. The NH2-terminal of the peptide was proved to be blocked because it could not be degraded by Edman degradation. Based on the physicochemical and biochemical characteristics of the inhibitor and compared with other active peptides known to be in the pancreas, the inhibitor is probably a new active peptide that might play an important role in homeostasis of carbohydrate metabolism.
History of Diabetes, the Journal (1952–1991): Editor's Swan Song
Authors: Paul Robertson R
Published: September 2013

Diabetes has provided scientific information in diabetes-related areas of basic and clinical research since 1952. This brief historical overview of the journal's activities and published articles is offered as an illustration of the remarkable strides in diabetes-related research that have taken place over the past 40 years.
Prevention of Recurrence of IDDM in Islet-Transplanted Diabetic NOD Mice by Adjuvant Immunotherapy
Authors: Wang Thur , Singh Bhagirath , Warnock Garth L , Rajotte Ray V
Published: September 2013

Insulin-dependent diabetes mellitus (IDDM) involves the destruction of the insulin-producing cells in the islets of Langerhans. One possible cure is by transplanting the islet cells; however, transplanted islets, even between identical twins, are subject to autoimmune destruction by the disease process, resulting in diabetes recurrence. We recently reported that complete Freund's adjuvant (CFA), an immunomodulating agent, prevented development of autoimmune diabetes in the NOD mouse. In this study, we evaluated adjuvant therapy in prevention of autoimmune destruction and rejection of transplanted islets in diabetic NOD mice. After transplantation, untreated syngeneic islet recipients (n = 16) initially became normoglycemic and then hyperglycemic, with a median survival time (MST) of the graft of 17 days. When CFA was administered at the time of transplantation, 11 of 13 CFA-treated syngeneic islet recipients remained normoglycemic long term (> 100 days) with an MST > 107 days. Ten of 11 mice maintained indefinite normoglycemia until the conclusion of follow-up (101 to 172 days). When adjuvant therapy was used in conjunction with allogeneic islet transplantation, graft survival was not extended, with MST being similar to the untreated allogeneic islet recipients (12 [n = 5] and 13 [n = 5] days, respectively). The extended acceptance of second syngeneic islet grafts by CFA-treated mice indicates that the persistent autoimmunity against the transplanted islets can be reversed in the diabetic NOD mice after CFA treatment.
Glucagon Immunoneutralization in Diabetic Rats Normalizes Urea Synthesis and Decreases Nitrogen Wasting
Authors: Almdal Thomas P , Holst Jens J , Heindorff Hans , Vilstrup Hendrik
Published: September 2013

To study the effect of glucagon neutralization on urea synthesis in diabetic rats, animals with newly induced (75 mg/kg streptozocin) experimental diabetes mellitus were divided into two groups. One group was given one weekly injection of nonimmune rabbit serum (n = 6), and the other group was given one weekly injection of a specific high-titer antibody against pancreatic glucagon (n = 6). Four weeks later, serum-treated diabetic rats had fasting glucagon concentrations 2–3 times higher than nondiabetic controls given one weekly injection of saline (control). Plasma glucagon binding capacity of diabetic rats given glucagon antibodies was 10–15 times higher than the glucagon concentration. A second group of nondiabetic controls were given nonimmune serum. Blood glucose concentration and urinary glucose output were identical in both groups of diabetic animals. Food intake doubled in both groups of diabetic rats. In control rats, the accumulated nitrogen balance, determined weekly for 4 wk, was positive at 81 ± 3.1 mmol/96 h; in serum-treated diabetic rats, the accumulated nitrogen balance was negative, −8.3 ± 2.4 mmol/96 h throughout the 4 wk, whereas it was higher at 4.7 ± 2.3 mmol/96 h in the glucagon antibody-treated diabetic rats (P < 0.05). The capacity of urea synthesis determined after 4 wk in both groups of nondiabetic controls was 8.4 ± 1.6 μmol · min−1 · 100 g−1 body wt; in the serum-treated diabetic group, it was 21.3 ± 1.9 μmol · min−1 · 100 g−1 body wt (P < 0.01 vs. control); and in the glucagon antibody–treated diabetic group, it was 8.6 ± 0.7 μmol · min−1 · 100 g−1 body wt (P < 0.01 vs. serum-treated diabetic). In the serum-treated diabetic group, the nitrogen content of muscle and heart fell significantly to 56 and 81% of control rats, respectively (P < 0.05). In the glucagon antibody–treated diabetic group, muscle and heart nitrogen content fell significantly less, i.e., to 67 and 88%, respectively (P < 0.05 vs. serum-treated diabetic). The results demonstrate that glucagon immunoneutralization in diabetic rats normalizes the capacity for hepatic aminonitrogen-to-urea conversion and reduces diabetic nitrogen loss by 25% without affecting hyperglycemia.
Upregulation of GLUT2 mRNA by Glucose, Mannose, and Fructose in Isolated Rat Hepatocytes
Authors: Asano Tomoichiro , Katagiri Hideki , Tsukuda Katsunori , Lin Jiann-Liang , Ishihara Hisa Mitsu , Yazaki Yoshio , Oka Yoshitomo
Published: September 2013

Previously, demonstrated that GLUT2 mRNA and protein are increased in liver of streptozocin-induced diabetic rats. To examine the mechanisms whereby GLUT2 mRNA is regulated, we cultured isolated hepatocytes in the absence and presence of various concentrations of glucose. Culture of hepatocytes in high glucose concentration (27.8 mM) for 20 h induced a 3.2-fold increase in GLUT2 mRNA levels compared with hepatocytes cultured without D-glucose. Interestingly, D-mannose and D-fructose could substitute for D-glucose to elevate the GLUT2 mRNA level, whereas 3-O-methyl-D-glucose, 2-deoxy-D-glucose, and sucrose, which were not metabolized or taken up by the cells, were without effect. Insulin had no significant effect on GLUT2 mRNA levels in hepatocytes in the presence or absence of D-glucose. Therefore, the regulation of the GLUT2 gene by D-glucose in hepatocytes is contrary to that reported for GLUT1 and GLUT4 genes, which are downregulated by D-glucose. These results also suggest that the elevated GLUT2 mRNA level observed in diabetic rat liver is due to the high blood glucose concentration rather than to insulin deficiency.
Mechanistic Studies of Advanced Glycosylation End Product Inhibition by Aminoguanidine
Authors: Edelstein Diane , Brownlee Michael
Published: September 2013

Aminoguanidine-HCl inhibits the formation of advanced glycosylation end products (AGEs) in vitro and in vivo, but the mechanism by which this occurs has not been determined. Aminoguanidine inhibited glucose-derived AGE formation on RNase A by 67–85% at aminoguanidine-glucose molar ratios of 1:5 to 1:50 without affecting the concentration of Amadori products. Fast–atom-bombardment mass spectrometry of RNase peptides incubated with glucose alone or with glucose plus aminoguanidine showed that aminoguanidine inhibited the formation of AGEs without forming an adduct with glycosylated peptide. These data suggest that the primary mechanism of aminoguanidine action is reaction with Amadori-derived fragmentation products in solution. These findings are relevant to the potential clinical use of aminoguanidine in the prevention of diabetic complications.
NOR/Lt Mice: MHC-Matched Diabetes-Resistant Control Strain for NOD Mice
Authors: Prochazka Michal , Serreze David V , Frankel Wayne N , Leiter Edward H
Published: September 2013

NOR/Lt is an insulitis-resistant and diabetes-free strain produced from an isolated genetic contamination within an NOD/Lt pedigree line. The albino coat-color phenotype, strain-specific endogenous retroviral profile, and skin graft tests indicated an NOD/Lt × C57BL/KsJ outcross-backcross segregant as the source of the contaminating genome. Analysis of 53 polymorphic DNA, biochemical, and immunologic markers distinguishing NOD/Lt from C57BL/KsJ revealed that 4 chromosomes (chromosomes 2, 4, 11, and 12) in NOR/Lt contained C57BL/KsJ-derived genes. The remaining markers on 14 chromosomes, including the diabetogenic H-2g7 complex on chromosome 17, were of NOD origin. Although completely resistant to cyclophosphamide-induced diabetes, NOR/Lt mice exhibited the same peripheral T-lymphocyte accumulation characteristic of NOD/Lt. Similarly, NOR/Lt peritoneal macrophages exhibited depressed interleukin-1 secretion characteristic of NOD/Lt. In addition to their diabetes resistance, NOR/Lt mice were distinguished from NOD/Lt by exhibiting more robust suppressor T-lymphocyte function. Outcross of NOR/Lt with NOD/Lt to generate heterozygosity at those chromosomal segments, defined by C57BL/KsJ markers in NOR/Lt parentals, did not produce insulitis or diabetes in F1 females. However, these F1 females were sensitive to cyclophosphamide-induced diabetes. In summary, the NOR/Lt strain is an MHC-matched diabetes-resistant control strain for NOD/Lt. Moreover, NOR/Lt will help identify the location and function of a non-MHC gene or genes capable of conferring resistance against insulitis and diabetes.