bluuebunny/crossref_metadata_2025 huggingface dataset:
Oscillatory Insulin Secretion After Pancreas Transplant
Authors: O′Meara Niall M , Sturis Jeppe , Blackman John D , Byrne Maria M , Jaspan Jonathan B , Roland Dianne C , Thistlethwaite J Richard , Polonsky Kenneth S
Published: September 2013

In vivo studies of β-cell secretory function have demonstrated the existence of rapid insulin oscillations of small amplitude recurring every 8–15 min in normal subjects. This study evaluated the effects of pancreas transplant on rapid insulin oscillations. Samples for glucose, insulin, and C-peptide were drawn during constant glucose infusion at 2-min intervals for 90 min from six successful Px patients with type I diabetes mellitus, from six normal nondiabetic control subjects, and from three Kx subjects. A computerized algorithm (ULTRA) was used for pulse detection. In the Px group, the average insulin pulse period was significantly shorter than in both the control and Kx groups (Px 8.1 ± 0.5, control 12.5 ± 0.7, Kx 12.4 ± 0.5 min, P < 0.0005). By contrast, the C-peptide pulse periods (Px 16.8 ± 2.3, control 14.7 ± 1.2, Kx 15.3 ± 1.5 min) were similar in the three groups. Spectral analysis confirmed that the frequency of the insulin pulses was increased in the Px group. The absolute amplitude of the insulin pulses was greater in the Px group (P < 0.001) while the amplitude of the C-peptide pulses did not differ between the groups. Cross-correlation analysis demonstrated maximal correlation coefficients at a lag of 0 min between insulin and C-peptide (control r = 0.33, P < 0.0001; Kx r = 0.17, P = 0.06) and between insulin and glucose (control r = 0.21, P < 0.001; Kx r = 0.20, P < 0.02) in the control and Kx groups, respectively, whereas no significant correlations were observed at any lag in the Px group. Thus, insulin oscillations, which are of larger amplitude and occur with greater frequency than in normal control subjects, may be detected in the peripheral circulation after pancreas transplant. Although their persistence after transplant supports the hypothesis that they reflect the existence of an intrinsic islet cell pacemaker, the increased frequency of the oscillations in the Px group raises the possibility that this intrinsic pacemaker in normal subjects may be modified by extrinsic neural factors.
Lower-Extremity Amputation: Incidence, Risk Factors, and Mortality in the Oklahoma Indian Diabetes Study
Authors: Lee Jennifer S , Lu Min , Lee Vivian S , Russell Dana , Bahr Carman , Lee Elisa T
Published: September 2013

Oklahoma Indians with NIDDM (n = 1012) underwent a baseline examination in 1972–1980. The incidence of and risk factors for first lower-extremity amputation were estimated. The mortality rates of amputees using data from 875 patients who had no previous history of amputation and who underwent follow-up examination between 1987 and 1991 are presented. The mean age of the 875 patients was 51.6 ± 10.8 yr, and the mean duration of diabetes was 6.6 ± 6.1 yr. After a mean follow-up time of 9.9 ± 4.3 yr, the incidence rate of first LEA among diabetic Oklahoma Indians was 18.0/1000 person-yr. The incidence rate was two times higher in men than in women. In both sexes, significant risk factors (P < 0.05) were retinopathy and duration of diabetes. Fasting plasma glucose, use of insulin, and systolic blood pressure were significant for men only. For women, plasma cholesterol and diastolic blood pressure were additional risk factors. Compared with the mortality rate of 33.5/1000 person-yr among nonamputees, the rate among amputees was 55.5/1000 person-yr. The 5-yr survival rate after first amputation was 40.4%. For the amputees, the most common causes of death were diabetes (37.3%), cardiovascular disease (29.1%), and renal disease (7.3%). The incidence and mortality rates in diabetic Oklahoma Indians were higher than those reported in Pima Indians and other diabetic populations. To lower the incidence of lower-extremity amputation in this high-risk population, preventive action through education, foot care programs, and early detection of lesions must be intensified.
A Microtiter Well Assay System to Measure Insulin Activation of Insulin Receptor Kinase in Intact Human Mononuclear Cells: Decreased Insulin Effect in Cells From Patients With NIDDM
Authors: Klein Harald H , Kowalewski Britta , Drenckhan Maren , Neugebauer Sabine , Matthaei Stephan , Kotzke Gerd
Published: September 2013

A sensitive microtiter well–based assay for the measurement of insulin activation of insulin receptor kinase in intact human circulating mononuclear cells has been developed and characterized. Mononuclear cells from 100–150 ml blood were incubated with various insulin concentrations to activate the receptor kinase. The cells were then solubilized in the presence of phosphatase and kinase inhibitors and the receptors immobilized to microwells coated with anti-insulin receptor antibody (efficiency of receptor immobilization > 85%). Receptor kinase activity and binding activity were then consecutively measured in the same wells. Insulin incubation of the cells increased the kinase activity three- to fourfold with a half-maximal effect at 5 nM and a maximal effect at 87 nM. In mononuclear cells from 16 subjects with NIDDM, the insulin effect on receptor kinase activation was significantly reduced compared with 16 nondiabetic control subjects (0.135 ± 0.016 vs. 0.195 ± 0.024 fmol P.fmol binding activity−1 · min−1, respectively; P < 0.05). We conclude that; 1) it is possible to determine insulin activation of receptor kinase in intact cells in this easily accessible human tissue; 2) insulin activation of insulin receptor kinase is impaired in intact mononuclear cells from patients with NIDDM; and 3) the finding that kinase activation in NIDDM is reduced in a tissue that, according to the literature, contains only the A isoform of the insulin receptor, suggests that mechanisms other than a different abundance of the A and B insulin receptor isoforms must exist that contribute to the decreased kinase activity in NIDDM.
Murine Insulinoma Cell Line With Normal Glucose-Regulated Insulin Secretion
Authors: Efrat Shimon , Leiser Margarit , Surana Manju , Tal Michael , Fusco-Demane David , Fleischer Norman
Published: September 2013

Pancreatic βTC lines derived from insulinomas arising in transgenic mice expressing SV40 Tag under control of the insulin promoter manifest a differentiated β-cell phenotype and secrete insulin in response to glucose. Previously reported βTC lines respond to subphysiological extracellular glucose levels compared with normal β-cells. Recently, several βTC lines were developed with normal glucose-regulated insulin secretion from insulinomas obtained by breeding of the RIP-Tag transgene from the original C57BI/6 mouse strain into the C3HeB/FeJ strain. One of these βTC lines, βTC7, was characterized in detail. βTC7 cells express GLUT2 and have levels of glucokinase and hexokinase activity similar to those of normal islets. As a result these cells exhibit a normal glucose concentration dependency for glycolysis and insulin secretion, thus representing an accurate model of β-cell function. On continuous propagation in culture, βTC7 cells acquired a response to lower extracellular glucose levels. This change was associated with a fourfold increase in hexokinase activity, without significant changes in glucokinase activity and glucose uptake rates. These findings suggest an important role for glucose phosphorylation rates in regulation of the β-cell insulin secretory response to glucose.
Time Course of Increased Lipid and Decreased Glucose Oxidation During Early Phase of Childhood Obesity
Authors: Le Stunff Catherine , Bougnères Pierre-François
Published: September 2013

To determine the time course of metabolic dysfunctions in recent active obesity, we studied basal energy expenditure and lipid and glucose oxidation in 31 obese children (duration of obesity 1–11.5 yr), compared with 14 lean age-matched control subjects. Using indirect calorimetry in basal overnight fasting conditions, we found that obese children produced 15% more energy than control subjects. Obese children oxidized twice as much lipid (56 ± 4 mg/min) as normal children (25 ± 5 mg/min, P < 0.0005), so that lipid oxidation provided 61 ± 6% of overall energy production (vs. 33 ± 3% in control subjects, P < 0.0005). This increase of lipid oxidation was already present in the earlier stages of obesity. Glucose oxidation was diminished in the obese (93 ± 6 mg/min) compared with the control children (136 ± 6 mg/min, P < 0.0005) and accounted for only 39 ± 3% of energy production (67 ± 6% in control subjects, P < 0.0005). This decrease was not present initially and appeared after ∼ 4 yr and worsened with obesity duration (r = 0.72, P < 0.0005). The results were similar when lipid and glucose oxidation were normalized to body surface area or lean body mass. We hypothesize that increased lipid oxidation is one of the earlier dysfunctions observed in recent-onset obesity and that lipid oxidation may induce a progressive decrease of glucose oxidation, insulin resistance, and increased fasting insulin secretion.
Superantigen-Like Effects and Incidence of Diabetes in NOD Mice
Authors: McDuffie Marcia , Ostrowska Alina
Published: September 2013

The population of T-cells that develops in any individual can be divided into families based on sequence differences in the β-chain variable region of the T-cell receptor heterodimer. Major histocompatibility complex products and endogenous retroviral gene products have both been shown to exert powerful influences on the frequency distribution of T-cell receptor β-chain variable region families in the mouse. In most mouse strains, these repertoire modifiers appear to be fully functional early in mouse development and shape a repertoire of antigen specificities that remains essentially unchanged from the first weeks of life until old age. In NOD mice, an inbred mouse model of type I diabetes, puberty in males coincides with a β-chain variable region-specific T-cell expansion that mimics the results of exposure to exogenous superantigens in immunologically mature animals. The subsequent behavior of this subset indicates that it may play a role in the relative protection of male NOD mice from complete pancreatic β-cell destruction and overt diabetes.
Insulin Stimulates Hydrolysis of Plasmanylinositol-Glycan and Phosphatidylinositol-Glycan in Rat Adipocytes: Insulin-Induced Generation of Inositol Glycan, Alkylacylglycerol, and Diacylglycerol
Authors: Suzuki Susumu , Taneda Yoshinobu , Hirai Satoshi , Satoh Yoshinori , Toyota Takayoshi
Published: September 2013

Insulin binding to its receptor has been known to induce hydrolysis of phosphatidylinositol-glycan and release inositol-glycan and diacylglycerol, two putative second messengers of insulin actions. We metabolically labeled and purified PIG in rat cultured adipocytes. The treatment of [3H]glycerol-labeled PIG with phosphatidylinositol-specific phospholipase C released [3H]glycerol-labeled DAG and [3H]glycerol-labeled 1-alkyl,2-acyl-glycerol, suggesting that PIG has not only PIG but also plasmanylinositol-glycan moiety. Insulin induced hydrolysis of PIG/PMIG and generation of IG, DAG, and AAG in a dose-dependent manner. This report shows the first demonstration of insulin-sensitive PMIG in rat adipocytes. These results provide evidence that insulin-induced generation of IG, DAG, and AAG might be early events in the insulin-signaling mechanism in rat adipocytes, and insulin-releasable AAG seems to mediate some actions of insulin.
Polymorphic Microsatellite Repeat Markers at the Glucokinase Gene Locus Are Positively Associated With NIDDM in Japanese
Authors: Noda Kaoru , Matsutani Akira , Tanizawa Yukio , Neuman Rosalind , Kaneko Toshio , Permutt M Alan , Kaku Kohei
Published: September 2013

To assess the possible role of glucokinase defects contributing to a genetic susceptibility to NIDDM in Japanese, allelic frequencies of two microsatellite repeat polymorphisms, one in the 3′-flanking region (GCK1) and the other in the 5′-flanking region (GCK2) of the human glucokinase gene, were analyzed in subjects with NIDDM and in nondiabetic control subjects. After typing 107 diabetic and 74 nondiabetic subjects, we found four GCK1 alleles (Z, Z2, Z4, Z6) and six GCK2 alleles (0, −4, −2, 2, 4, 8). The frequency distribution of GCK1 alleles was different between the two groups (P = 0.005), although not significant after correction for multiple comparisons. The Z4 allele was found more frequently in diabetic than in nondiabetic subjects (23 vs. 10%, P = 0.002). This was still significant after correction for multiple comparisons (P < 0.05). The frequency distribution of GCK2 alleles was not different between the two groups. However, the −2 allele was more common in diabetic than in nondiabetic subjects (P = 0.044), although not significant after adjusting for multiple comparisons. Clinical characteristics were compared between the diabetic subjects with Z4 and/or −2 allele and those without either of these two alleles. No differences were found in the age of diagnosis, positive family history, mode of therapy, current HbA1c, or daily urinary C-peptide immunoreactivity excretion between the two groups. We demonstrated a significant association between GCK1 and GCK2 alleles and NIDDM. The results indicate that the polymorphic alleles GCK1 and GCK2 could be genetic markers in NIDDM in Japanese, suggesting a relationship between glucokinase defects and the susceptibility to NIDDM in this population.
Human Glucagon-Like Peptide-1 Receptor Gene: Localization to Chromosome Band 6p21 by Fluorescence In Situ Hybridization and Linkage of a Highly Polymorphic Simple Tandem Repeat DNA Polymorphism to Other Markers on Chromosome 6
Authors: Stoffel Markus , Espinosa Rafael , Michelle M Le Beau , Bell Graeme I
Published: September 2013

Glucagon-like peptide-1 is a fragment of proglucagon secreted by intestinal L-cells. It has potent glucose-dependent insulin secretory effects and also suppresses gastric acid secretion in the stomach. The biological actions of GLP-1 are mediated by the GLP-1 receptor, the structure of which has recently been determined. Defects in insulin secretion are a common feature of NIDDM and as such the GLP-1 receptor is a candidate for contributing to the development of this clinically and genetically heterogeneous disorder. As a first step in determining the role of the GLP-1 receptor in the development of NIDDM, we have isolated the human GLP-1 receptor gene and mapped it to chromosome 6, band p21.1, using the technique of fluorescence in situ hybridization. We also identified a simple tandem repeat DNA polymorphism in the human GLP-1 receptor gene of the form (TG)n. This DNA polymorphism has 14 alleles and a heterozygosity of >0.8. We have used this DNA polymorphism to localize the GLP-1 receptor gene within the genetic map of the short arm of chromosome 6. This DNA polymorphism will facilitate genetic studies of the contribution of the GLP-1 receptor gene to impaired β-cell function and NIDDM.
Induction of Hypoglycemia Unawareness by Asymptomatic Nocturnal Hypoglycemia
Authors: Veneman Thiemo , Mitrakou Asimina , Mokan Marian , Cryer Philip , Gerich John
Published: September 2013

Hypoglycemia has been incriminated as a possible factor responsible for development of the hypoglycemia unawareness phenomenon in patients with type I diabetes. Many patients with this condition, however, do not have a history of recent hypoglycemia. Because asymptomatic nocturnal hypoglycemia commonly occurs in type I diabetes, we tested the hypothesis that such episodes might be capable of inducing this phenomenon. Accordingly, autonomic and neuroglycopenic symptoms, counterregulatory hormone responses, and cognitive function were assessed during standardized insulin-induced hypoglycemia in 10 normal volunteer subjects on two occasions—once after induction of asymptomatic nocturnal hypoglycemia and once after control studies in which saline rather than insulin was infused overnight. Compared with control experiments, asymptomatic nocturnal hypoglycemia increased the threshold (required greater hypoglycemia for initiation) and reduced the magnitude of autonomic and neuroglycopenic symptoms, counterregulatory hormone responses, and cognitive dysfunction during subsequent hypoglycemia (all, P < 0.05). These results indicate that asymptomatic hypoglycemia may induce hypoglycemia unawareness and, thus, may explain why not every patient with this condition has a history of prior hypoglycemia. Our results therefore support the concept that in type I diabetes this phenomenon may be largely attributable to antecedent hypoglycemia.
Linkage Analysis and Molecular Scanning of Glucokinase Gene in NIDDM Families
Authors: Zouali Habib , Vaxillaire Marine , Lesage Suzanne , Sun Fang , Velho Gilberto , Vionnet Nathalie , Chiu Ken , Passa Philippe , Permutt Alan , Demenais Florence , Cohen Daniel , Beckmann Jacques , Froguel Philippe
Published: September 2013

Mutations in the glucokinase gene are a major cause of maturity-onset diabetes of the young. To evaluate the contribution of this gene to the development of late-onset NIDDM, linkage analyses between DNA polymorphisms at the glucokinase locus and NIDDM were performed in 79 multigenerational French families. In addition, all exons and the islet promoter region of glucokinase gene from 1 affected member from each family as well as from 17 unrelated women with previous gestational diabetes were amplified by polymerase chain reaction and screened for mutations by single-strand conformational polymorphism and DNA sequencing. Linkage of glucokinase and NIDDM was significantly rejected under all models tested. However, in 1 family, the lod score was 2.30, and we found a nucleotide substitution at the position –30 in the islet promoter region that cosegregated with diabetes. The proband of this family was a gestational diabetic individual. No other mutation in glucokinase was found in the 79 NIDDM families. We identified a missense mutation (TGG257→CGG257) in exon 7 of glucokinase gene from 1 of 17 women with gestational diabetes, which was present in all diabetic members of her family. This family is likely to be a cryptic maturity-onset diabetes of the young, as 4 younger members, carrying this mutation, were subsequently found to be hyperglycemic. In conclusion, no evidence was obtained to incriminate glucokinase as a major gene for late age of onset NIDDM. Diabetic families with mutations in glucokinase must be carefully investigated, to differentiate cryptic maturity-onset diabetes of the young from late-onset NIDDM. Furthermore, pregnancy reveals diabetes in women carrying a glucokinase defect.
Insulin Resistance and Insulin Secretion Are Determinants of Oral Glucose Tolerance in Normal Individuals
Authors: Reaven Gerald M , Brand Richard J , Ida Chen Y -D , Mathur Ashwini K , Goldfine Ira
Published: September 2013

Plasma glucose values after oral glucose challenge vary widely in nondiabetic subjects. We have now evaluated the role of insulin resistance in determining the plasma glucose response to oral glucose in 74 volunteer subjects with normal glucose tolerance. In these subjects, we determined the plasma glucose and insulin responses over a 3-h period to a 75-g oral glucose challenge, and the steady-state plasma glucose concentration during a continuous infusion of somatostatin, glucose, and insulin (a quantitative measure of insulin resistance). The plasma glucose response was defined as the incremental increase in plasma glucose concentration above the fasting value for 3 h after the oral glucose challenge. Multiple regression analysis was used to define the relationship between the dependent variable (plasma glucose response) and various predictors of this response. These analyses indicated that both the steady-state plasma glucose and the incremental insulin response during the first 30 min after the glucose load were significant predictors of the plasma glucose response. In those individuals in whom insulin action was impaired and the 30-min plasma insulin response was decreased, plasma glucose values reached higher levels. When standardized regression coefficients were determined, the incremental glucose response was directly correlated with steady-state plasma glucose (r = 0.700, P < 0.001) and inversely with the insulin response during the first 30 min (r = 0.268, P = 0.023). Furthermore, the correlation between steady-state plasma glucose and glucose response was significantly greater (P < 0.005) than that between the glucose response and 30-min insulin concentration. These data demonstrate that both insulin action and insulin secretion are determinants of the plasma glucose response to oral glucose in individuals with normal glucose tolerance.
North-American Twins With IDDM: Genetic, Etiological, and Clinical Significance of Disease Concordance According to Age, Zygosity, and the Interval After Diagnosis in First Twin
Authors: Kumar Dinesh , Gemayel Nabil S , Deapen Dennis , Kapadia Deepak , Yamashita Peter H , Lee Martha , Dwyer James H , Roy-Burman Pradip , Bray George A , Mack Thimas M
Published: September 2013

In 224 twin pairs (132 monozygotic, 86 dizygotic, and 6 of uncertain zygosity) in whom the index twin had developed IDDM before 30 yr of age, 51 of the co-twins (38 monozygotic, 10 dizygotic, and 3 of uncertain zygosity) subsequently became diabetic. On the basis of concordance ratios, which were significantly discrepant (P < 0.01) between monozygotic and dizygotic twins, the substantial genetic role in IDDM etiology is confirmed. For the monozygotic co-twin of an IDDM case, the relative risk is significantly related to an early age at proband diagnosis (P < 0.01 for 0–4 vs. 5–9 yr of age). However, among monozygotic co-twins at any age, IDDM risk decreases as time passes after the proband diagnosis (P < 0.01 for 0–23 vs. ≥ 24 mo after a proband diagnosis at 5–9 yr of age). Moreover, a structural-equation analysis suggests a profound contribution to liability (as much as 79%) from the twins' shared environment. Risk to like-sex male dizygotic co-twins is as high as that to monozygotic co-twins, significantly higher than that to like-sex female dizygotic co-twins (P < 0.005), and even higher than that to male co-twins in unlike-sex dizygotic pairs (P < 0.05). Overall, the risk to the dizygotic co-twin of a case is significantly higher (P < 0.001) than that to a non-twin sibling, as reported in the literature. The observed male excess is consistent with reported patterns of IDDM in experimental animals, and in certain circumstances in humans. Taken together, these observations suggest an important early acquired determinant of IDDM, independent of genetic determinants. On the basis of Kaplan-Meier IDDM-free survival curves, if the proband is diagnosed before 15 yr of age, the long-term risk to the co-twin is estimated at 44% (monozygotic) and 19% (dizygotic); it reaches 65% for the co-twin of a monozygotic proband diagnosed before 5 yr of age. An IDDM discordant period of no more than 3 yr was observed in 60% of the pairs destined to become concordant, offering a very brief window for intervention following the recognition of high risk.
Human, Rodent, and Canine Pancreatic β-cells Express a Sodium Channel α1-Subunit Related to a Fetal Brain Isoform
Authors: Philipson Louis H , Kusnetsov Andrey , Larson Turi , Zeng Yijun , Westermark Gunilla
Published: September 2013

Voltage-dependent, tetrodotoxin-sensitive Na+ currents have been identified by the patch-clamp technique in rodent, canine, and human pancreatic β-cells, but their exact role in insulin secretion remains uncertain. Misler et al. recently reviewed data showing that human and rat β-cell action potentials differ, in that trains of Na+-dependent action potentials are seen in human (and canine) cells, but the vast majority of rat β-cell Na+ channels are inactivated. We have now identified Na+ channel α1-subunit mRNAs expressed in normal adult human, canine, and rat islets, and two insulinoma cell lines, by mRNA amplification (reverse transcription followed by polymerase chain reaction). cDNA sequencing showed that all amplified human islet products and the majority of rodent islet cDNAs are most closely related to the rat brain III α1-subunit isoform, previously found to be expressed primarily in fetal rat brain. Canine islets expressed both brain II and brain III isoforms. Reverse transcription followed by polymerase chain reaction experiments with hamster and mouse insulinoma cell lines also showed expression of the message related to the rat brain III isoform. In situ hybridization of human pancreas sections using a partial human Na+ channel III cDNA probe showed the message to be expressed in the majority of islet cells, and not in the acinar tissue, confirming its presence in pancreatic β-cells. Thus, the predominant Na+ channel α1-subunit gene expressed in human and rat insulin secreting cells is most highly related to a fetal rat brain isoform, despite the differences in the role of this channel in the β-cell action potentials of these two species.
Factors Responsible for Impaired Fibrinolysis in Obese Subjects and NIDDM Patients
Authors: McGill Janet B , Schneider David J , Arfken Cynthia L , Lucore Charles L , Sobel Burton E
Published: September 2013

Accelerated atherosclerosis is the leading cause of death in patients with non-insulin-dependent diabetes mellitus (NIDDM). Impaired endogenous fibrinolytic activity may accelerate atherosclerosis by exposing vascular luminal wall surfaces to persistent and recurrent thrombi and clot-associated mitogens. This study was conducted to further characterize endogenous fibrinolysis in lean and obese nondiabetic subjects and in NIDDM patients and to identify mechanisms responsible for the alterations identified. Obese and diabetic subjects had threefold elevations of plasma concentrations of plasminogen activator inhibitor type 1 (PAI-1) compared with values in lean control subjects. Despite the lack of significant differences in plasma concentrations of tissue-type plasminogen activator in the obese and diabetic subjects, both basal and stimulated endogenous fibrinolytic activities were decreased. The decreases were associated with increased activity of PAI-1 in plasma, in turn correlated with increased concentrations of immunoreactive insulin and C-peptide. These results are consistent with our previous observations demonstrating direct stimulatory effects of insulin and its precursors on cellular expression of PAI-1 in vitro and observations by others demonstrating decreased basal fibrinolytic activity in NIDDM patients. Impaired endogenous fibrinolytic activity could lead to prolonged or recurrent exposure of luminal surfaces of vessel walls to microthrombi and clot-associated mitogens that may accelerate atherosclerosis in hyperinsulinemic subjects.
Induction of Tolerance to Islet Xenografts in a Concordant Rat-to-Mouse Model
Authors: Goss John A , Nakafusa Yuji , Finke Edward H , Flye M Wayne , Lacy Paul E
Published: September 2013

Induction of tolerance to concordant rat islet xenografts (150 Wistar-Furth [WF] islets) in streptozocin-induced (STZ) diabetic mice (C57BU/6) was determined at three different sites for islet implantation (thymus, kidney capsule, and liver). Islets transplanted into the thymus or kidney capsule were either fresh or cultured at 24°C for 7 days, and the mice received a single injection of either anti-mouse lymphocyte serum (MALS) alone or anti-rat lymphocyte serum (RALS) and MALS. Islets transplanted into the liver via the portal vein were cultured at 24°C for 7 days, and the mice received a single injection of MALS and RALS. To document the induction of tolerance, recipients with islet xenografts surviving >100 days were made diabetic again by STZ (thymus and liver) or nephrectomy (kidney capsule) and received a second transplant of 150 fresh WF islets in the kidney capsule. Kidney capsule placement of fresh or cultured islets with MALS alone or MALS and RALS did not induce tolerance in a significant number of recipients. The intrathymic transplantation of fresh or cultured islets with MALS alone resulted in prolonged WF islet xenog raft survival (mean survival time of 39.7 ± 7.9 days) but did not result in tolerance, whereas the administration of MALS and RALS with the intrathymic placement of fresh or cultured islets induced tolerance in ∼50% of the mice. Intrahepatic transplantation of cultured islets with MALS and RALS resulted in tolerance to donor islets in 90% of the recipients. Donor specificity was evaluated by a third major histocompatability complex–disparate fresh Lewis islet xenograft. Approximately 50% of these xenografts were not rejected, suggesting that the tolerance may not be haplotype-specific. The mechanisms involved in inducing tolerance to islet xenografts are not clearly established; however, this study clearly demonstrates that tolerance to xenogeneic islets can be achieved by using a brief period of immunosuppression in the intrathymic or intrahepatic transplantation site, with intrahepatic implantation achieving tolerance in a higher percentage of recipients than the intrathymic site.
A New Antidiabetic Agent, BRL 49653, Reduces Lipid Availability and Improves Insulin Action and Glucoregulation in the Rat
Authors: Oakes Nicholas D , Kennedy Catherine J , Jenkins Arthur B , Laybutt D Ross , Chisholm Donald J , Kraegen Edward W
Published: September 2013

Thiazolidinediones offer promise as oral insulin-sensitizing agents. The effects of a new, high-potency compound (BRL 49653, SmithKline Beecham, Epsom, U.K.) were examined in insulin-resistant (high-fat–fed, HF) and control (high-starch–fed, HS) rats. The diet period was 3 weeks, with a BRL 49653 (10 μmol · kg−1 · day−1) or vehicle gavage on the last 4 days. Then basal or euglycemic clamp studies were performed on animals in the conscious fasted state. In the basal state, BRL 49653 produced many similar metabolic responses in HF and HS rats (reduced insulin, glycerol, ketone body, and nonesterified fatty acid levels, reduced whole body glucose turnover, reduced brown adipose tissue glucose metabolism, and increased cardiac glucose metabolism and GLUT4 levels). In contrast, under euglycemic clamp conditions (500 pmol/l insulin), BRL 49653 only induced changes in the HF group (increased glucose infusion rate from 12.2 ± 0.9 to 21.6 ± 1.1 mg · kg−1 · min−1 [P < 0.001], increased insulin suppressibility of hepatic glucose production [P < 0.01], and increased glucose uptake in muscle [P < 0.01]). BRL 49653 significantly reduced liver but not muscle triglyceride content in HF rats. We conclude that the agent has a general effect on lowering circulating lipid and insulin levels, manifested similarly in normal and insulin-resistant rats, but that enhancement of peripheral insulin action is confined to insulin-resistant rats. Therefore, the hypoinsulinemic action of the thiazolidinediones is probably not related simply to improved peripheral insulin sensitivity. The pattern of individual tissue response to BRL 49653 suggests that altered lipid availability is an important mediator of its effects on glucose metabolism.
Glucose Effectiveness in Two Subtypes Within Impaired Glucose Tolerance: A Minimal Model Analysis
Authors: Taniguchi Ataru , Nakai Yoshikatsu , Doi Kentaro , Fukushima Mitsuo , Nagata Itaru , Kawamura Hitomi , Imura Hiroo , Suzuki Masashige , Tokuyama Kumpei
Published: September 2013

To clarify the event that is involved in the pathogenesis of impaired glucose tolerance (IGT), we studied 15 individuals with IGT and 15 subjects with normal tolerance using the minimal model approach. Our IGT subjects were characterized by normal insulin secretory responses to oral glucose and mild impairments in insulin sensitivity (SI) and glucose effectiveness (SG) at basal and zero insulin. Next, we classified our IGT subjects into two subpopulations: one with normal insulin sensitivity (SI: 0.92 ± 0.11 × 10(−4) min−1 · pmol/l−1 and the other with insulin resistance (SI: 0.31 ± 0.06 × 10−4 min−1 · pmol/l−1, P < 0.05). The populations did not differ with respect to body mass index and fasting plasma glucose level. Basal plasma insulin level was higher in the insulin-resistant group (84.8 ± 23.3 pmol/l) than in the insulin-sensitive group (48.7 ± 6.8 pmol/l), but the difference was not statistically significant. The absolute insulin secretory responses to oral glucose were significantly higher in the resistant group (83,205 ± 17,787 pmol/l × min) than in the sensitive group (24,727 ± 3,591 pmol/l × min, P < 0.01), whose absolute responses were similar to those of normal control subjects (24,576 ± 2,767 pmol/l × min). No significant difference was observed in SG between the resistant (0.016 ± 0.002 min−1) and sensitive (0.013 ± 0.002 min−1, P > 0.05) type of IGT, but SG was significantly type of IGT, but SG was significantly decreased in both groups compared with normal control subjects (0.023 ± 0.002 min−1, P < 0.05–0.01). particular population is composed of at least two sub-populations: one with insulin resistance and higher insulin response to oral glucose and the other with normal insulin sensitivity and normal insulin response to oral glucose. In both, SG was significantly impaired compared with normal control subjects.
Antibodies to Glutamic Acid Decarboxylase and P2-C Peptides in Sera From Coxsackie Virus B4-Infected Mice and IDDM Patients
Authors: Hou Jun , Said Celli , Franchi David , Dockstader Pamela , Chatterjee Nando K
Published: September 2013

The possible role of amino acid sequence and epitope homologies between a protein P2-C of Coxsackie virus B4 and human GAD in the development of host-specific immune response in insulin-dependent diabetes mellitus (IDDM) (molecular mimicry) was investigated. Peptide antibodies to the P2-C protein, GAD65, and GAD67 were raised to analyze their immunoreactivity by enzyme-linked immunosorbent assay and immunoblotting with GAD purified from the brain and pancreas of mice that develop hyperglycemia after the infection. Additionally, antibody reactivity to these peptide antigens was assessed in sera from the virus-infected mice and IDDM patients. All three peptide antisera reacted very strongly with homologous peptides; P2-C antiserum cross-reacted with GAD65 as efficiently as GAD65 antiserum with P2-C, but no cross-reaction was detected between P2-C and GAD67 although cross-reaction between the two GADs was quite pronounced. P2-C antiserum immunocomplexed with GAD65 from mouse brain or pancreas, whereas GAD65 and GAD67 antisera both immunocomplexed with the two GADs from these sources. Most of the sera from virus-infected mice were reactive to brain and pancreas GAD65 and also to P2-C peptide, whereas some reacted to GAD65 and a few to GAD67 peptides. A number of IDDM sera reacted with mouse GAD65 and also with P2-C and GAD65 peptides, whereas only a few reacted with GAD67 peptide. The immunoreactivity of the mouse and IDDM sera to P2-C and GAD65 peptides was blocked by pre-adsorption with mouse GAD. The results suggest that molecular mimicry may play a role in the pathogenesis of the disease.
Tumor Necrosis Factor α: A Key Component of the Obesity-Diabetes Link
Authors: Hotamisligil Gökhan S , Spiegelman Bruce M
Published: September 2013

Recent data have suggested a key role for tumor necrosis factor (TNF)-α in the insulin resistance of obesity and non-insulin-dependent diabetes mellitus (NIDDM). TNF-α expression is elevated in the adipose tissue of multiple experimental models of obesity. Neutralization of TNF-α in one of these models improves insulin sensitivity by increasing the activity of the insulin receptor tyrosine kinase, specifically in muscle and fat tissues. On a cellular level, TNF-α is a potent inhibitor of the insulin-stimulated tyrosine phosphorylations on the β-chain of the insulin receptor and insulin receptor substrate-1, suggesting a defect at or near the tyrosine kinase activity of the insulin receptor. Given the clear link between obesity, insulin resistance, and diabetes, these results strongly suggest that TNF-α may play a crucial role in the systemic insulin resistance of NIDDM. This may allow for new treatments of disorders involving resistance to insulin.
Cytokeratins as Markers of Ductal Cell Differentiation and Islet Neogenesis in the Neonatal Rat Pancreas
Authors: Bouwens Luc , Wang Ren-Nian , Blay Emmy De , Pipeleers Daniël G , Klöppel Günter
Published: September 2013

Cytokeratins (CKs) serve as immunocytochemical markers of epithelial cells. We found that duct cells of the neonatal and adult rat pancreas express CKs 7, 19, and 20. Because pancreatic endocrine cells are thought to derive from duct cells, we examined their expression of CKs 7, 19, and 20 during the neonatal period and the proliferative activity of the different cell types in and around islets. Immunocytochemical analysis revealed that the islets of the neonatal pancreas, in contrast to those of adults, strongly expressed CKs 7, 19, and 20, particularly within a peripheral mantle zone that was continuous with the epithelium of adjacent ductules. This pattern was found during the first 2 weeks of life when significant islet growth occurred as determined by morphometry and bromodeoxyuridine (BrdU) labeling. Moreover, BrdU labeling kinetics indicated that the growth of neonatal islets occurred in the peripheral mantle region characterized by intense CK20 and CK19 immunoreactivity and not in the region composed of differentiated endocrine cells. These observations strongly suggest that proliferating ductal cells associated with islets represent a pool of islet β- and non-β-precursor cells.
Glutamic Acid Decarboxylase (GAD65) Autoantibodies in Prediction of β-Cell Function and Remission in Recent-Onset IDDM After Cyclosporin Treatment
Authors: Petersen Jacob Sten , Dyrberg Thomas , Karlsen Allan E , Mølvig Jens , Michelsen Birgitte , Nerup Jørn , Mandrup-Poulsen Thomas ,   Canadian-European Randomized Control Trial Group
Published: September 2013

We have investigated whether glutamic acid decarboxylase (GAD) autoantibodies (GAD65 Ab) were affected by cyclosporin therapy and were related to subsequent noninsulin-requiring remission and loss of glucagon-stimulated C-peptide response in 132 recent-onset insulindependent diabetes mellitus (IDDM) patients treated with cyclosporin or placebo for 12 months. GAD65 Ab were detected in a quantitative radioligand assay using as tracer recombinant, in vitro translated, human islet [35S]methionine-labeled GAD65. GAD65 Ab were found at onset in 66% (87 of 132) of IDDM patients and in 1% (1 of 100) of healthy control subjects. The prevalence of GAD65 Ab and median GAD65 Ab levels did not change in serum samples taken 3, 6, 9, and 12 months after study entry in either the cyclosporin- or the placebo-treated groups. The presence or absence of GAD65 Ab at study entry did not predict non-insulin-requiring remission in either cyclosporin- or placebo-treated patients. However, the relative (compared with 0 months) glucagon-stimulated C-peptide response was more than 30% lower in GAD65 Ab+ patients receiving placebo at 9 and 12 months compared with the GAD65 Ab− placebo patients (P < 0.035). Islet cell cytoplasmic antibody (ICA) and GAD65 Ab+ placebotreated patients showed no significant differences in stimulated C-peptide levels compared with those who were ICA− and GAD65 Ab+, suggesting that ICA was not independently associated with loss of (β-cell function. We conclude that GAD65 Ab at diagnosis may predict a more rapid loss of β-cell function, a finding of importance when selecting individuals at risk of developing IDDM or recent-onset IDDM patients for intervention therapy.
STZ Transport and Cytotoxicity: Specific Enhancement in GLUT2-Expressing Cells
Authors: Schnedl Wolfgang J , Ferber Sarah , Johnson John H , Newgard Christopher B
Published: September 2013

The glucose analog streptozotocin (STZ) has long been used as a tool for creating experimental diabetes because of its relatively specific β-cell cytotoxic effect, but the mechanism by which systemic injection of STZ causes β-cell destruction is not well understood. In the current study, we have used insulinoma (RIN) and AtT-20ins cell lines engineered for overexpression of GLUT2 or GLUT1 to investigate the role of glucose transporter isoforms in mediating STZ cytotoxicity. The in vivo effects of STZ were evaluated by implantation of RIN cells expressing or lacking GLUT2 into athymic nude rats. The drug had a potent cytotoxic effect on RIN cells expressing GLUT2, but had no effect on cells lacking GLUT2 expression, as indicated by histological analysis and measurement of the blood glucose levels of treated animals. The preferential cytotoxic effect of STZ on GLUT2-expressing cell lines was confirmed by in vitro analysis of GLUT2-expressing and untransfected RIN cells, as well as GLUT2- and GLUTl-overexpressing AtT-20ins cells. Consistent with these data, only GLUT2-expressing RIN or AtT-20ins cells transported STZ efficiently. We conclude that expression of GLUT2 is required for efficient killing of neuroendocrine cells by STZ, and this effect is related to specific recognition of the drug as a transported substrate by GLUT2 but not GLUT1
Beneficial Influence of Glycemic Control Upon the Growth and Function of Transplanted Islets
Authors: Juang Jyuhn-Huarng , Bonner-Weir Susan , Wu Ying-Jian , Weir Gordon C
Published: September 2013

Syngeneic transplantation of 200 mouse islets under the kidney capsule usually fails to cure streptozocin-induced diabetes. We hypothesized that this number of islets, if engrafted in a normoglycemic environment, could expand their mass and improve their function to restore normoglycemia. Therefore, 200 freshly isolated mouse islets were transplanted under the capsule of each kidney of diabetic mice. Two weeks after transplantation, the recipients were normoglycemic, and one of the two grafts was removed. Removal of the graft was followed by transient hyperglycemia. At day 14 after graft removal, the β-cell mass and insulin content of the remaining graft had increased 2.3- and 2.1-fold, respectively. At day 3 after graft removal, the replication rate of β-cells increased threefold, and the mean individual β-cell crosssectional area, an indicator of cell size, was also increased. Perfusion of the kidney bearing the remaining graft showed biphasic insulin responses to high glucose and arginine 14 days after one graft removal. These data indicate that maintaining a period of near-normoglycemia after islet transplantation enhances the performance of an islet graft that would otherwise be expected to fail.
Transgenic approaches to the pathogenesis of NIDDM
Authors: Moller David E
Published: September 2013

The pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) involves complex interactions between multiple physiological defects, both genetic and acquired. The application of transgenic technology to create animal models that address questions concerning NIDDM (and obesity) is a very recent development that is now gaining rapid momentum and receiving deserved attention. In general, transgenic methods afford new opportunities to alter the site or level of expression of functional genes in vivo, to transfer novel foreign genes into animals, to prevent the expression of specific genes, or to replace genes with specific genetic variants. Two general approaches can be applied: 1) conventional transgenics, the transfer to and expression of new genetic information in animals; and 2) gene targeting, the disruption or replacement of specific endogenous genes. Recent transgenic initiatives have provided important insights into 1) the mechanism of glucose-stimulated insulin secretion and the role of potential defects in this system, 2) the regulated expression of genes that control hepatic glucose production, 3) the role of specific molecules that mediate the actions of insulin, and 4) the elucidation of factors that contribute to in vivo regulation of energy balance and body composition. Emerging transgenic strategies should have a dramatic impact on future efforts to assess the function of newly identified molecules implicated in the regulation of in vivo glucose homeostasis and to determine the roles of candidate loci or specific mutations uncovered during the search for new NIDDM susceptibility genes.
Reversal of Hypoglycemia Unawareness, But Not Defective Glucose Counterregulation, in IDDM
Authors: Dagogo-Jack Samuel , Rattarasarn Chatchalit , Cryer Philip E
Published: September 2013

To test the hypothesis that the neuroendocrine (including autonomic) responses to hypoglycemia are dissociated from the symptomatic responses to hypoglycemia in insulin-dependent diabetes mellitus (IDDM) patients with hypoglycemia awareness and during reversal of hypoglycemia unawareness in IDDM, we used the hyperinsulinemic stepped hypoglycemic (5.0, 4.4, 3.9, 3.3, 2.8, and 2.2 mmol/l) clamp technique to quantitate these responses in nondiabetic control subjects and IDDM patients with hypoglycemia awareness and with hypoglycemia unawareness. The latter were restudied after 3 days, 3–4 weeks, and 3 months of scrupulous avoidance of iatrogenic hypoglycemia. At baseline, symptom responses were virtually nil in unaware patients (P = 0.0001 vs. nondiabetic); these were increased in aware patients (P = 0.0183 vs. nondiabetic). In contrast, several neuroendocrine responses were comparably reduced in both unaware and aware patients: epinephrine (P = 0.0222 and 0.0156), pancreatic polypeptide (P = 0.0004 and 0.0003), glucagon (P = 0.0112 and 0.0109), and cortisol (P = 0.0214 and 0.0450). In initially unaware patients, symptom responses increased (P = 0.0001) during avoidance of hypoglycemia. Demonstrable after 3 days, these were entirely normal after 3–4 weeks and 3 months. In contrast, none of the neuroendocrine responses increased. Thus, we conclude that several neuroendocrine responses to hypoglycemia (including the adrenomedullary and parasympathetic components of the autonomic response) can be dissociated from symptomatic responses in IDDM patients with hypoglycemia awareness and during reversal of hypoglycemia unawareness in IDDM. Avoidance of iatrogenic hypoglycemia sufficient to reverse the clinical syndrome of hypoglycemia unawareness did not reverse the key elements (deficient glucagon and epinephrine responses) of the clinical syndrome of defective glucose counterregulation. This implies that the mechanisms of hypoglycemia unawareness and of defective glucose counterregulation are, at least in part, different in IDDM.
Pressor and Subpressor Doses of Angiotensin II Increase Insulin Sensitivity in NIDDM: Dissociation of Metabolic and Blood Pressure Effects
Authors: Morris Andrew D , Petrie John R , Ueda Shinichiro , Connell John M C , Elliott Henry L , Small Michael , Donnelly Richard
Published: September 2013

There is evidence that the renin-angiotensin system may be involved in the metabolic as well as the cardiovascular features of diabetes and that pressor doses of angiotensin II (ANG II) increase insulin sensitivity in parallel with blood pressure (BP) in healthy subjects, but the effects of ANG II on insulin sensitivity have not been previously reported in patients with non-insulin-dependent diabetes mellitus (NIDDM). In a randomized, double-blind, placebo-controlled, crossover study, 11 patients with NIDDM attended 3 study days to evaluate the effects of a 3-h infusion of subpressor and pressor doses of ANG II on whole body insulin sensitivity using the euglycemic hyperinsulinemic clamp. BP and heart rate were recorded, and blood samples were collected for serum insulin, C-peptide, potassium, catecholamines, plasma renin activity, and plasma ANG II concentrations. Plasma levels of ANG II (means ± SD) were 9 ± 4, 29 ± 9, and 168 ± 47 pmol/ml after placebo, low dose infusion, and high dose infusion, respectively. The higher dose of ANG II was associated with significant increases in BP (e.g., 18 mmHg systolic BP at 150 min) and plasma aldosterone. Whole body insulin sensitivity was 23.8 ± 12.7 mumol glucose.kg−1 · min−1 after placebo and 30.6 ± 12.7 and 27.2 ± 13.3 following low and high dose ANG II infusions, respectively (P < 0.05, analysis of variance). In summary, acute infusion of ANG II, with or without an increase in BP, increases insulin sensitivity in normotensive patients with NIDDM. The dissociation of metabolic and BP effects of ANG II suggests that hemodynamic alterations and redistribution of cardiac output might not be the sole underlying mechanism in patients with NIDDM.