bluuebunny/crossref_metadata_2025 huggingface dataset:
High Prevalence of NIDDM and Impaired Glucose Tolerance in Indian, Creole, and Chinese Mauritians
Authors: Dowse Gary K , Gareeboo Hassam , Zimmet Paul Z , Alberti K George M M , Tuomilehto Jaakko , Fareed Djamil , Brissonnette L Gaetan , Finch Caroline F ,   For the Mauritius Noncommunicable Disease Study Group
Published: September 2013

Mauritius, a multiethnic island nation in the southwestern Indian Ocean, has one of the world's highest diabetes mortality rates. The prevalence of both impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) was investigated in 5080 Muslim and Hindu Indian, Creole (mixed African, European, and Indian origin), and Chinese Mauritian adults aged 25–74 yr who were selected by random cluster sampling. Based on a 75-g oral glucose tolerance test and World Health Organization criteria, the age-standardized prevalence of IGT was significantly greater in women (19.7%, 95% confidence interval [CI] 18.1–21.2) than in men (11.7%, CI 10.5–12.8). By contrast, the prevalence of NIDDM was similar in men (12.1%, Cl 10.9–13.4) and women (11.7%, Cl 10.5–12.8) for all ethnic groups combined. The sex difference in IGT prevalence was seen in all ethnic groups, but for NIDDM, the sex difference was not consistent across ethnic groups. However, age-and sex-standardized prevalence of IGT and NIDDM was remarkably similar across ethnic groups (16.2 and 12.4% in Hindu Indians, 15.3 and 13.3% in Muslim Indians, 17.5 and 10.4% in Creoles, and 16.6 and 11.9% in Chinese, respectively). Three new cases of diabetes were diagnosed for every two known cases. The high prevalence of abnormal glucose tolerance in Indian subjects is consistent with studies of other migrant Indian communities, but the findings in Creole and, in particular, Chinese subjects are unexpected. Potent environmental factors shared between ethnic groups in Mauritius may be responsible for the epidemic of glucose intolerance.
Comparison of Cytokine Effects on Mouse Pancreatic α-Cell and β-Cell Lines Viability, Secretory Function, and MHC Antigen Expression
Authors: Hamaguchi Kazuyuki , Leiter Edward H
Published: September 2013

Cytokine effects on permanent cell lines of transformed mouse pancreatic α- and β-cells were compared. The β–tumor cell 1 (βTC1) line (from an adenoma created in transgenic mice expressing the SV40 large T-antigen oncogene under control of the rat insulin II promoter) produced insulin predominantly, although small quantities of intracellular glucagon (100:1 insulin to glucagon) were detectable by radioimmunoassay. The αTC1 line (from an adenoma created in transgenic mice expressing the SV40 large T-antigen oncogene under control of the rat preproglucagon promoter) produced not only glucagon but also considerable quantities of insulin (4:1 glucagon to insulin) and preproinsulin mRNA. We therefore cloned αTC1 cells and obtained 12 glucagon-producing clonai cell lines that did not produce levels of insulin detectable by radioimmunoassay. Analysis by Northern blotting of total RNA from two lines, αTC1 clones 6 and 9, confirmed the absence of preproinsulin mRNA. No somatostatin or pancreatic polypeptide was detected by immunohistochemical staining in αTC1 clones 6 or 9 or βTC1 cells. Rat recombinant γ-interferon (IFN-γ; 5–250 U/ml) or mouse recombinant interleukin 1 (IL-1; 1–25 U/ml) individually inhibited DNA synthesis in βTC1 cells after 3 days of treatment. The two cytokines in combination acted synergistically to further depress DNA synthesis and increase cytotoxicity. In contrast, αTC1 clone 9 cells were not sensitive to inhibition of DNA synthesis by each cytokine individually, although glucagon synthesis was inhibited. The combination of these cytokines caused marked inhibition of DNA and glucagon syntheses in αTC1 clone 9 cells. αTC1 clone 9 cells were somewhat more resistant to the cytotoxic action of the combined cytokines than were βTC1 cells. Incubation with 50 U/ml IFN-γ induced class II MHC molecules (I-Ab, I-Ad, and I-Ed) and enhanced the constitutive expression of class I molecules (H-2Kb and H-2Kd) on the cell surfaces of βTC1, uncloned αTC1, and αTC1 clones 6 and 9. Thus, these cell lines are heterozygous for MHC alleles derived from both parental strains used in the construction of the transgenic mice [C57BL/6J (H-2b) and DBA/2J (H-2d) ]. Class II gene transcription induced by IFN-γ was confirmed in βTC1 and αTC1 clone 9 cells by Northern blot analysis with Aα-, Aβ-, Eα-, and Eβ-DNA probes. The differences in sensitivity to the cytotoxic action of cytokines may relate to the preferential destruction of β-cells in the early stage of insulin-dependent diabetes. Because class I and II MHC expression was enhanced or induced by IFN-γ in both the α- and β-cell lines, the ability to induce MHC molecules in itself is not sufficient to explain β-cell– specific autoimmune recognition associated with insulin-dependent diabetes.
Effect of Diet on Incidence of Diabetes in Nonobese Diabetic Mice
Authors: Coleman Douglas L , Kuzava Joan E , Leiter Edward H
Published: September 2013

Nonobese diabetic/Lt mice exhibit a diabetes incidence >70% in females at 30 wk of age. In studies designed to see whether increased dietary carbohydrate, fat, or protein influenced the severity or age at onset of the syndrome, we fed semipurified AIN-76 diet adulterated with increased amounts of these ingredients. Surprisingly, all AIN-76–based diets greatly reduced the expected incidence of diabetes at 30 wk. In addition, a hypoallergenic infant formula, Pregestimil, containing casein hydrolysate in place of protein, completely prevented diabetes up to 1 yr of age. To assess how dietary components might modulate the diabetes incidence, we adulterated standard AIN-76 diet with skim milk, gluten, brewer's yeast, or a natural-ingredient rodent open-formula mouse diet (Old Guilford 96 [OG96]). No increase in diabetes incidence was seen with skim milk (10%) or wheat gluten (10%), whereas brewer's yeast (10%) and OG96 (25%) added to AIN-76 increased the incidence compared to mice fed OG96 only. The diabetogenic factor or factors in OG96 could be extracted by chloroform plus methanol (2:1), leaving little activity in the residue. We conclude that diet is a critical factor in diabetes development and that unknown chloroform-methanol–soluble substances in natural-ingredient chow not found in semipurified diets can enhance the development of diabetes in genetically susceptible mice.
Regional Brain Glucose Metabolism and Blood Flow in Streptozocin-Induced Diabetic Rats
Authors: Jakobsen Johannes , Nedergaard Maiken , Aarslew-Jensen Marianne , Diemer Nils Henrik
Published: September 2013

Brain regional glucose metabolism and regional blood flow were measured from autoradiographs by the uptake of [3H]-2-deoxy-D-glucose and [14C]iodoantipyrine in streptozocin-induced diabetic (STZ-D) rats. After 2 days of diabetes, glucose metabolism in the neocortex, basal ganglia, and white matter increased by 34, 37, and 8%, respectively, whereas blood flow was unchanged. After 4 mo, glucose metabolism in the same three regions was decreased by 32, 43, and 60%. This reduction was paralleled by a statistically nonsignificant reduction in blood flow in neocortex and basal ganglia. It is suggested that the decrease of brain glucose metabolism in STZ-D reflects increased ketone body oxidation and reduction of electrochemical work.
Decreased Fluidity of Polymorphonuclear Leukocyte Membrane in Streptozocin-Induced Diabetic Rats
Authors: Masuda Midori , Murakami Takashi , Egawa Hiroshi , Murata Kenjiro
Published: September 2013

Using flow cytometry with the excimer-forming lipid technique with pyrenedecanoic acid, we measured membrane fluidity of polymorphonuclear leukocytes (PMNs) from 20 streptozocin (STZ)-induced diabetic rats. Diabetes mellitus was induced in male Sprague-Dawley rats (body wt 243 ± 11 g) with an injection of 25 mg/kg i.v. STZ. Membrane fluidity of PMNs was significantly lower at 2 wk after the STZ injection when serum glucose reached the plateau (31.1 ± 5.8 mM), and after 3 wk, membrane fluidity remained unchanged. In 7 STZ-resistant rats for which serum glucose was <10 mM at 2 wk after the STZ injection, gradual normalization in membrane fluidity was observed. PMN membrane fluidity at each week correlated inversely with respective serum glucose levels 1 wk previously (r = −0.76) but not with serum lipid levels. Cross-incubation studies ascribed this observation to factors in the diabetic rat serum. Glycosylated protein, which was separated from diabetic rat serum, decreased membrane fluidity of control rat PMNs. Human diabetic subjects have an increased risk for infection, which may be due partly to altered membrane fluidity of their PMNs.
Effects of Insulin on Hemodynamics and Metabolism in Human Forearm
Authors: Natali Andrea , Buzzigoli Giuseppe , Taddei Stefano , Santoro Donatella , Cerri Maurizio , Pedrinelli Roberto , Ferrannini Eleuterio
Published: September 2013

We investigated the vascular response (blood flow and resting vascular resistance) and the metabolic response (exchange of metabolites and respiratory gases) to local insulin administration in the forearms of healthy young volunteers with the use of the perfused-forearm technique. In the postabsorptive state, the deep tissues of the forearm (mostly skeletal muscle) took up glucose (mean ± SE 1.09 ± 0.17 μmol · min−1 · dl−1 forearm vol), β-hydroxybutyrate (0.267 ± 0.130 μmol · min−1 · dl1), and O2 (9.96 ± 1.02 μmol · min−1 · dl−1) and released lactate (0.284 ± 0.098 μmol · min−1 · dl−1), glycerol (0.029 ± 0.012 μmol · min−1 · dl−1), citrate (0.091 ± 0.030 μmol · min−1 · dl1), alanine (0.184 ± 0.044 μmol · min−1 · dl−1), Co2 (7.36 ± 0.97 μmol · min−1 · dl−1), and protons (12.1 ±1.4 pmol · min−1 · dl−1). Forearm blood flow (by venous occlusion plethysmography) was 2.95 ± 0.18 ml · min−1 · dl−1, and intra-arterial systolic/diastolic blood pressure was 116 ± 3/76 ± 2 mmHg. Local indirect calorimetry indicated dominance of fat as the oxidative substrate (RQ 0.76 ± 0.09) and an energy expenditure rate of 1.03 ± 0.11 cal · min−1 · dl−1 forearm vol. One hundred minutes of intra-arterial insulin infusion (deep venous plasma insulin concn of 125 ± 11 μU/ml) had no detectable effect on forearm blood flow, resting forearm vascular resistance, heart rate, or blood pressure. Local hyperinsulinemia significantly stimulated glucose uptake (to 4.79 ± 0.61 μmol · min−1 · dl−1 forearm vol, P <0.001), lactate and pyruvate release (to 0.710 ± 0.093 and 0.032 ± 0.016 μmol · min−1 · dl−1 forearm vol, respectively; P < 0.01 for both), potassium uptake (0.76 ± 0.22 μeq · min−1 · dl−1, P < 0.001), and free fatty acid uptake (0.123 ± 0.041 μmol · min−1 · dl−1 forearm vol, P < 0.05); glycerol balance switched to a net uptake (P < 0.001), alanine release was restrained by 33% (P < 0.05), and β-hydroxybutyrate and citrate release were unchanged. Despite these metabolic changes, local rates of substrate oxidation and energy expenditure were not altered by insulin. In contrast, forearm proton release was significantly stimulated by insulin (to 14.8 ±1.4 pmol · min−1 · dl−1 P < 0.02). Proton release was also found to be directly related to resting forearm vascular resistance independent of the effect of insulin (multiple r = 0.64, P < 0.001). We conclude that, in the deep tissues of human forearm, physiological hyperinsulinemia 1) has no acute hemodynamic action, 2) stimulates glucose uptake and restrains lipolysis but does not change the pattern of substrate oxidation, 3) exerts no thermogenic effect, and 4) promotes net extrusion of protons. The fact that, in the same district, vascular resistance bears a direct relationship to proton release suggests that resting vascular tone and skeletal muscle metabolism may be related characteristics in humans.
Glucokinase Gene Structure: Functional Implications of Molecular Genetic Studies
Authors: Magnuson Mark A
Published: September 2013

Glucokinase is expressed in both the liver and the pancreatic β-cell and plays a key role in the metabolism of glucose by both tissues. Expression of this enzyme is differentially regulated; hepatic glucokinase is stimulated by insulin and repressed by cAMP, whereas β-cell glucokinase activity is increased by glucose. Recently, the glucokinase gene has been characterized and was found to contain two different transcription control regions. One region regulates transcription of the gene in the liver, whereas the other region, which lies at least 12 kilobases further upstream, controls transcription in the pancreatic β-cell. The finding of two different transcription control regions in a single glucokinase gene provides a genetic basis for the tissue-specific differential regulation of glucokinase and will serve as the basis for further studies to identify and characterize the different regulatory elements and factors in the liver and β-cell, which are presumably involved. Comparison of different glucokinase cDNAs isolated from hepatic, insulinoma, and islet cDNA libraries indicates that at least three glucokinase isoforms are generated by differential RNA processing of the glucokinase gene transcripts. Whether any of these glucokinase isoforms are functionally unique remains to be determined.
Fetal Hyperinsulinemia and Protein Turnover in Fetal Rat Tissues
Authors: Johnson John D , Dunham Tracy , Wogenrich F James , Greenberg Robert E , Loftfield Robert B , Skipper Betty J
Published: September 2013

The effects of fetal hyperinsulinemia on protein turnover in various tissues of fetal rats were determined after transuteral injection of insulin to rat fetuses at day 19 of gestation. Tissue protein content was measured on the subsequent days of gestation (days 20–22), and protein synthesis was determined at day 20 of gestation in fetal tissues after intravenous injection of [3H]phenylalanine into the maternal circulation, followed by measurements of tissue free and protein-bound phenylalanine specific radioactivity in fetal diaphragm, brain, heart, and liver. Rates of protein degradation in these fetal tissues were calculated by subtracting protein accretion rates from rates of protein synthesis. The injection of insulin to rat fetuses at day 19 of gestation resulted in relative macrosomia versus saline-injected controls from the same litter (body wt at day 20 of gestation, 3.26 ± 0.15 g for saline-injected fetuses and 3.60 ± 0.25 g for insulin-injected fetuses, P < 0.001) and increased protein and RNA content of brain, heart, and liver. Although fractional rates of protein synthesis were not significantly elevated in tissues from the hyperinsulinemic fetuses, absolute rates of protein synthesis were increased in brain, heart, and liver of hyperinsulinemic fetuses. Hyperinsulinemia did not reduce calculated rates of protein breakdown in fetal brain, heart, or liver but did in fetal diaphragm. We conclude that the major effect of fetal hyperinsulinemia on protein turnover in rats is to increase protein synthesis in selected tissues without simultaneously affecting protein breakdown.
Effect of Puberty on Initial Kidney Growth and Rise in Kidney IGF-I in Diabetic Rats
Authors: Bach Leon A , Jerums George
Published: September 2013

Prepubertal subjects have a low incidence of diabetic nephropathy compared with duration-matched postpubertal subjects. At puberty, there is an increase in insulinlike growth factor I (IGF-I) levels, and because IGF-I has been implicated in the early kidney enlargement of experimental diabetes, we studied the development of kidney enlargement and kidney IGF-I levels in prepubertal (aged 5 wk) and postpubertal (aged 13 wk) Sprague-Dawley rats during the 7 days after induction of diabetes with streptozocin. Kidney weight in postpubertal diabetic animals was significantly greater than in postpubertal controls by day 2 (1.46 ± 0.06 vs. 1.16 ± 0.09 g, P < 0.05), and by day 7, kidney weight had increased by 36% (1.61 ± 0.07 vs. 1.18 ± 0.08 g, P < 0.001). Despite comparable blood glucose levels in the prepubertal and postpubertal diabetic rats, kidney weight in prepubertal diabetic animals was significantly greater than in prepubertal controls by 14% on day 7 only (0.84 ± 0.01 vs. 0.73 ± 0.03 g, P < 0.05). Kidney IGF-I content was significantly elevated in diabetic postpubertal rats, peaking on day 1 (diabetic vs. control, 1082 ±156 vs. 543 ± 21 ng/g, P < 0.001) and day 2 but not in prepubertal diabetic rats. Thus, prepubertal diabetic rats have reduced and retarded kidney growth and attenuated kidney IGF-I levels, suggesting that local IGF-I accumulation may play an important role in diabetes-associated kidney enlargement.
Decreased VIP Content in Peripheral Nerve From Streptozocin-Induced Diabetic Rats
Authors: Noda Katsumi , Umeda Fumio , Ono Hiroshi , Hisatomi Akitaka , Chijiiwa Yoshiharu , Nawata Hajime , Ibayashi Hiroshi
Published: September 2013

After induction of diabetes with streptozocin (STZ-D) in rats, we measured vasoactive intestinal polypeptide (VIP) content in sciatic nerve and spinal cord obtained from nondiabetic, untreated STZ-D, and insulin-treated STZ-D rats. Eight weeks after the onset of diabetes, caudal nerve conduction velocity (NCV) in the untreated STZ-D rats (n = 13) was slower than in the controls (n = 11; mean ± SE 30.9 ± 0.6 vs. 41.4 ± 1.8 m/s, P < 0.001). The decrease in NCV was less marked in the insulin-treated STZ-D rats (n = 11; 36.3 ± 0.9 m/s, P < 0.05 vs. control). VIP content in sciatic nerve decreased in the untreated STZ-D rats (1.33 ± 0.23 ng/g wet wt) compared with the other groups (control, 3.10 ± 0.44, P < 0.01; insulin-treated STZ-D, 2.44 ± 0.55, P < 0.05). However, in spinal cord, VIP content was not significantly different among the three groups. The VIP levels in sciatic nerve showed a positive correlation with NCV (r = 0.430, P < 0.01). In addition, an inverse correlation between VIP levels and blood glucose levels was observed (r = −0.5624, P < 0.001). NCV was also inversely correlated with blood glucose levels (r = −0.7662, P < 0.001). Together with a previous morphological study, these findings suggest a possible causal relationship between reduced VIP content and diabetic neuropathy.
Glucokinase as Glucose Sensor and Metabolic Signal Generator in Pancreatic β-Cells and Hepatocytes
Authors: Matschinsky Franz M
Published: September 2013

This article reviews evidence for a pivotal role of glucokinase as glucose sensor of the pancreatic β-cells. Glucokinase explains the capacity, hexose specificity, affinities, sigmoidicity, and anomeric preference of pancreatic islet glycolysis, and because stimulation of glucose metabolism is a prerequisite of glucose stimulation of insulin release, glucokinase also explains many characteristics of this β-cell function. Glucokinase of the β-cell is induced or activated by glucose in contrast to liver glucokinase, which is regulated by insulin. Tissue-specific regulation corresponds with observations that liver and pancreatic β-cell glucokinase are structurally distinct. Glucokinase could play a glucose-sensor role in hepatocytes as well, and certain forms of diabetes mellitus might be due to glucokinase deficiencies in pancreatic β-cells, hepatocytes, or both.
Dependence of Antigen Expression on Functional State of β-Cells
Authors: Aaen Kim , Rygaard Jørgen , Josefsen Knud , Petersen Henrik , Brogren Carl-Henrik , Horn Thomas , Buschard Karsten
Published: September 2013

Antigen expression corresponding to anti-islet cell surface monoclonal antibodies IC2 and A2B5 was studied. IC2 is a rat-rat hybridoma autoantibody produced from the BB rat; among islet cells, IC2 is β-cell specific. A2B5 is an anti-ganglioside antibody described as labeling β-cells. Islets of Langerhans from Lewis rats were isolated and cultured for 18 h in RPMI-1640 with five different glucose concentrations (2.2, 3.3, 5.5, 11.1, and 18.3 mM). In some experiments, islets were precultured for 2 or 3 days. After isolation of islet cells and antibody labeling, the percent of IC2+ β-cells in the different groups increased from 33.3, 34.5, 40.9, and 57.2 to 58.6% (P < 10−6). For A2B5, the percent of labeled islet cells increased from 37.4, 41.8, 46.7, and 53.8 to 56.2% (P < 10−4). Thus, increasing glucose concentration leading to higher β-cell activity implies an increase in antigen expression. Neither A2B5 nor IC2 reacts with insulin, as shown by absorption experiments and immune electron microscopy of binding sites. Electron microscopy of IC2-gold-labeled islet cells substantiated the β-cell specificity of IC2. In conclusion, expression of the corresponding antigens to IC2 and A2B5 depends on the functional state of the β-cells; because this has been shown to be an important factor in the development of insulin-dependent diabetes, our findings may be of potential pathogenetic interest.
Decreased Ca2+-ATPase Activity After Glycosylation of Erythrocyte Membranes In Vivo and In Vitro
Authors: Flecha Francisco L González , Cbermúdez Mónica , Cédola Norberto V , Gagliardino Juan J , Rossi Juan R F C
Published: September 2013

Erythrocyte membranes drawn from diabetic patients with poor metabolic control have increased protein glycosylation and decreased Ca2+-ATPase activity. A significant relationship was found between these two parameters. Similar results were obtained when protein glycosylation and Ca2+-ATPase activity were measured in membranes from normal erythrocytes preincubated with glucose. In this condition, both parameters showed a clear time and dose dependence. Incubation of erythrocyte membranes instead of intact erythrocytes with glucose and glucose-6-phosphate strongly suggests that only the glycosylation of the membrane inner-surface proteins can affect Ca2+-ATPase activity. The simultaneous presence of 10 mM glucose and 5 mM ATP in the incubation medium did not affect the degree of erythrocyte membrane protein glycosylation but significantly blocked the inhibitory effect of glucose on Ca2+-ATPase activity. However, 5 mM ATP only partially blocked the inhibitory effect of 100 mM glucose, suggesting a competitive mechanism of glucose and ATP for the enzyme active site. Our results show that glycosylation of erythrocyte membrane proteins significantly inhibits Ca2+-ATPase activity. This effect could contribute to the development of the capillary closure process observed in diabetic patients. Furthermore, it could represent an index of a general impairment of enzyme function arising in cells chronically exposed to high glucose levels.
Inheritance of Diabetes Mellitus as Consequence of Gestational Hyperglycemia in Rats
Authors: Gauguier Dominique , Bihoreau Marie-Therese , Ktorza Alain , Berthault Marie-France , Picon Luc
Published: September 2013

Our study investigated whether a deterioration of glucose homeostasis and insulin secretion in adult female rats from hyperglycemic dams could be transmitted to the next generation independent of genetic interferences. Dams (F0) were rendered hyperglycemic by continuous glucose infusion during the last week of pregnancy. Females born of these rats (F1) exhibited glucose intolerance and impaired insulin secretion in vivo at adulthood. When they were 3 mo old, they were mated with males born of control dams. During pregnancy, their glucose tolerance remained impaired compared with that of controls. Consequently, F2 newborns of F1 hyperglycemic dams showed the main features of newborns from diabetic mothers: they were hyperglycemie, hyperinsulinemic, and macrosomic. As adults, they displayed basal hyperglycemia and defective glucose tolerance and insulin secretion. This indicates that the long-range deteriorating effects on glucose homeostasis of gestationai hyperglycemia in the F1generation are transmitted to the F2 generation and suggests that a perturbed fetal metabolic environment contributes to the inheritance of diabetes mellitus.
Vanadate Induction of Pancreatic Amylase mRNA in Diabetic Rats
Authors: Johnson Thomas M , Meisler Miriam H , Bennett Martha I , Willsky Gail R
Published: September 2013

Amylase activity and mRNA abundance are reduced to <1% of normal levels in diabetic rat pancreas. Administration of vanadate in drinking water restored normal amylase activity and amylase mRNA levels. These results demonstrate an effect of vanadate on pancreatic acinar cells and suggest that vanadate can mimic the effect of insulin on transcription of the pancreatic amylase gene.
Influence of Pancreas Transplantation on Cardiorespiratory Reflexes, Nerve Conduction, and Mortality in Diabetes Mellitus
Authors: Navarro Xavier , Kennedy William R , Loewenson Ruth B , Sutherland David E R
Published: September 2013

Cardiorespiratory reflexes (CRR) were studied by measuring heart-rate variation during 6 breaths/min respiration and a Valsalva maneuver in 232 insulin-dependent diabetic subjects. Abnormalities were found in 175 patients. During a 7-yr follow-up, 41 (23.4%) patients with abnormal and 2 (3.5%) with normal CRR tests died. The mortality rates of diabetic patients with abnormal autonomie function tests were 17% at 2.5 yr, 33% at 5 yr, and 40% at 7 yr, significantly higher (P < 0.002) than in patients with normal tests (rates of 4.6, 4.6, and 13.8% at the respective intervals). Nerve conduction studies (NCS) were indicative of somatic neuropathy in 148 of 205 patients. Mortality rates were higher in patients with abnormal NCS than in those with normal results (P < 0.025). Among patients with abnormal autonomie function, patients with a functioning pancreas transplantation (PTx) had better survival rates than patients with a failed PTx (P < 0.005) and, on long-term follow-up, better rates than patients without PTx. Similar results were found comparing the same group of patients who had abnormal NCS.
Insulinlike Effects of Vanadate on Hepatic Glycogen Metabolism in Nondiabetic and Streptozocin-Induced Diabetic Rats
Authors: Pugazhenthi Subbiah , Khandelwal Ramji L
Published: September 2013

The effect of oral administration of sodium orthovanadate for 5 wk on hepatic glycogen metabolism was studied in control and streptozocin-induced diabetic rats. Diabetes caused hyperglycemia (5-fold increase), hypoinsulinemia (85% decrease), and hyperglucagonemia (4-fold increase). There were also marked decreases in liver glycogen and activities of glycogen-metabolizing enzymes in liver. Although vanadate administration in control animals showed no significant effect on the various parameters measured except for a 70% decrease in plasma insulin, this treatment in diabetic rats restored these parameters to near control values. In diabetic rats, glycogen synthase a and the activity ratio (activity of glycogen synthase a divided by activity of total glycogen synthase) decreased to 30% of control levels and were restored to ∼70–80% of control values after vanadate administration. A similar pattern was observed for the activity of synthase phosphatase. The activities of glycogenolytic enzymes, i.e., phosphorylase (activity of phosphorylase a and activity of total phosphorylase), phosphorylase kinase, and protein kinase (in presence or absence of cAMP), were significantly decreased by 40–70% in diabetic rats. These enzyme activities were recovered to 70–100% of control values after vanadate treatment. Phosphorylase phosphatase was not altered by diabetes, but the vanadate treatment of both groups, i.e., control and diabetic rats, showed a 25% increase in its activity (P < 0.01). In conclusion, these results show insulinlike in vivo action of vanadate on various parameters related to hepatic glycogen metabolism.
Lack of Islet Amyloid Polypeptide Regulation of Insulin Biosynthesis or Secretion in Normal Rat Islets
Authors: Nagamatsu Shinya , Carroll Raymond J , Grodsky Gerold M , Steiner Donald F
Published: September 2013

We examined the effects of rat islet amyloid polypeptide (IAPP) on insulin biosynthesis and secretion by isolated rat islets of Langerhans. Culture of islets for 24 h in the presence of 10−6 M IAPP and 5.5 mM glucose had no effect on insulin mRNA levels. Similarly, the rates of proinsulin biosynthesis were not altered in islets incubated in 10−4–10−9 M IAPP and 5.5 mM glucose, nor was the rate of conversion of proinsulin to insulin changed at 10−6 M IAPP. Addition of 10−5 M IAPP to islets incubated in 11 mM glucose decreased the fractional insulin secretion rate; however, the secretion of newly synthesized proinsulin and insulin was not affected. These data indicate that it is unlikely that IAPP is a physiologically relevant modulator of insulin biosynthesis or secretion.
Alterations in Transfer and Lipid Distribution of Arachidonic Acid in Placentas of Diabetic Pregnancies
Authors: Kuhn Douglas C , Crawford Michael A , Stuart Marie J , Botti John J , Demers Laurence M
Published: September 2013

Placental tissue from nondiabetic term pregnancies and pregnancies complicated by maternal insulindependent diabetes mellitus (IDDM) was perfused in vitro to compare the transfer and lipid distribution of arachidonic acid (AA). Radiolabeled albumin-bound AA was administered into the maternal afferent circulation, and samples of fetal and maternal effluent were collected at 10-min intervals. Perfused placental tissue was collected at the end of each experiment. The effluent was analyzed for total radioactivity, and extracts were subjected to thin-layer chromatography for the assessment of radioactivity associated with various lipid fractions. Placental AA uptake was significantly increased in perfused tissue from diabetic pregnancies (0.88 vs. 1.72 nM · min−1 · g−1 in nondiabetic and IDDM, respectively; P < 0.01), as was AA transfer (0.22 vs. 0.42 ml/min in nondiabetic and IDDM, respectively; P < 0.01). However, transfer of the highly diffusible marker substance antipyrine was significantly reduced in IDDM placentas (1.79 vs. 2.49 ml/min in IDDM and nondiabetic, respectively; P < 0.01). Compared with nondiabetic placentas, incorporation of AA into triglyceride was significantly increased in both maternal and fetal effluents and in placental tissue from IDDM pregnancies, whereas the percentage of AA remaining unesterified was reduced in both placental tissue and fetal effluent. Incorporation of AA into phosphoglycerides was significantly reduced in placental tissue but increased in fetal effluent in placentas from IDDM pregnancies. The results of these studies suggest that transfer and lipid distribution of AA are significantly altered in placentas from IDDM pregnancies. These findings may be relevant to the increased incidence of abnormal fetal growth and development associated with IDDM pregnancies.
Kinetics of Insulin-Mediated and Non-Insulin-Mediated Glucose Uptake in Humans
Authors: Edelman Steven V , Laakso Markku , Wallace Penny , Brechtel Ginger , Olefsky Jerrold M , Baron Alain D
Published: September 2013

The kinetics of insulin-mediated glucose uptake (IMGU) and non-insulin-mediated glucose uptake (NIMGU) in humans have not been well defined. We used the glucose-clamp technique to measure rates of wholebody and leg muscle glucose uptake in six healthy lean men during hyperinsulinemia (∼460 pM) to study IMGU and during somatostatin-induced insulinopenia to study NIMGU at four glucose levels (4.5, 9,12, and 21 mM). To measure leg glucose uptake, the femoral artery and vein were catheterized, and blood flow was measured by thermodilution (leg glucose uptake = arteriovenous glucose difference [A-VG] × blood flow). With this approach, we found that, during hyperinsulinemia, both whole-body and leg glucose uptake increased in a curvilinear fashion at every glucose level, the highest glucose uptake values obtained being 139 ± 17 μmol · kg−1 · min−1 and 3656 ± 931 μmol · min−1 · leg−1, respectively. Leg blood flow increased twofold from 6.0 ± 1.7 to 11.7 ± 3.1 dl/min (P < 0.01) over the range of glucose and was correlated with whole-body glucose uptake (r = 0.55, P < 0.005). Leg muscle glucose extraction, independent of changes in blood flow, which is reflected by the A-VG, saturated over the range of glucose (1.28 ± 0.12, 2.22 ± 0.30, 2.92 ± 0.42, 3.02 ± 0.41 mM, NS between last 2 values) with a halfmaximal effective glucose concentration (EGS0) of 5.3 ± 0.4 mM. During insulinopenia, both whole-body and leg glucose uptake increased in a near-linear fashion; however, glucose uptake remained significantly lower than that seen with insulin stimulation, the highest glucose uptake values obtained being 22 ± 2 μmol · kg−1 · min−1 and 260 ± 34 μmol · min−1 · leg1, respectively. Leg blood flow was unchanged from the basal value (4.15 ± 0.63 dl/min) over the range of glucose studied, and A-VG increased at all glucose levels: 0.094 ± 0.010, 0.28 ± 0.03, 0.38 ± 0.04, and 0.59 ± 0.03 mM (P < 0.05 between any 2 consecutive values), with an EG50 of 10.0 ± 0.4 mM (P < 0.001 vs. IMGU). We conclude that 1) insulin increases the capacity for muscle A-VQ approximately fivefold; 2) muscle IMGU, independent of blood flow, displays an EG50 similar to the Km characteristic of the glucose-transport system (∼5–6 mM); 3) in contrast, NIMGU is a low-affinity glucoseuptake system; and 4) blood flow to insulin-sensitive tissue increases with insulin and glucose infusions and is an important determinant of the rate of in vivo glucose uptake.
Kinetics of In Vivo Muscle Insulin-Mediated Glucose Uptake in Human Obesity
Authors: Laakso Markku , Edelman Steven V , Olefsky Jerrold M , Brechtel Ginger , Wallace Penny , Baron Alain D
Published: September 2013

The kinetics of in vivo insulin-mediated glucose uptake in human obesity have not been previously studied. To examine this, we used the glucose-clamp technique to measure whole-body and leg muscle glucose uptake in seven lean and six obese men during hyperinsulinemia (∼2000 pM) at four glucose levels (∼4.5, ∼8.3, ∼13.5, and ∼23.5 mM). To measure leg glucose uptake, the femoral artery and vein were catheterized, and blood flow was measured by thermodilution (leg glucose uptake = arteriovenous glucose difference × blood flow). With this approach, we found that rates of whole-body and leg glucose uptake were significantly lower in obese than in lean subjects at each glucose plateau. Leg blood flow rates increased from 4.3 ± 0.4 to 6.5 ± 0.8 dl/min over the range of glucose in lean subjects (P < 0.05) but remained unchanged in obese subjects. The apparent maximal capacity (Vmax), based on whole-body and leg glucose uptake, was reduced in obese compared with lean subjects, but the apparent Km was similar in the lean and obese subjects (6-9 mM, NS). To assess the affinity of muscle for glucose extraction independent of changes in muscle plasma flow, we determined the mean half-maximal effective glucose concentration (EG50) and found it was similar in the lean and obese subjects (6.0 ± 0.3 vs. 6.0 ± 0.8 mM, NS). We conclude that 1) the kinetics of in vivo insulin-mediated glucose uptake in skeletal muscle in human obesity are characterized by reduced Vmax but normal Km; 2) the EG50 for insulin-mediated glucose extraction in skeletal muscle was 6 mM in both lean and obese subjects, consistent with a Km characteristic of the glucose-transport system; 3) obese subjects were unable to generate increases in blood flow in response to hyperglycemia under hyperinsulinemic conditions, and this contributed significantly to lower rates of leg and whole-body glucose uptake.
Importance of Impaired Insulin-Gene Expression in Occurrence of Diabetes in Obese Rats
Authors: Koh Gyohan , Seino Yutaka , Usami Masaru , Matsuo Takao , Ikeda Hitoshi , Yamamoto Taizo , Tsuda Kinsuke , Taminato Tomohiko , Imura Hiroo
Published: September 2013

To investigate the role of the β-cell in the occurrence of diabetes in obesity, longitudinal changes of insulingene expression and pancreatic insulin content were compared among genetically obese diabetic (Wistar fatty) rats, genetically obese nondiabetic (Zucker fatty) rats, and ventromedial hypothalamus (VMH)-lesioned obese rats. Plasma glucose levels were significantly elevated with age in Wistar fatty rats, whereas they were virtually unchanged in VMH-lesioned and Zucker fatty rats. Obesity and hyperinsulinemia were evident in VMH-lesioned rats 1 wk after the operation and in Zucker and Wistar fatty rats at 5 wk of age. In VMHlesioned rats, the pancreatic preproinsulin I mRNA (pplmRNA) level and pancreatic insulin content markedly increased approximately two- to threefold (P < 0.001) with the development of hyperinsulinemia, whereas sham-operated rats showed no significant change. In Zucker and Wistar lean rats, the pplmRNA level and pancreatic insulin content increased with age, corresponding to increases in body weight. In Zucker fatty rats, the pplmRNA level and pancreatic insulin content at 5 and 14 wk of age were significantly higher than those of lean littermates. The pplmRNA level in Zucker fatty rats at 14 wk of age reached 290% of that of their lean littermates (P < 0.001). On the other hand, the pplmRNA level and pancreatic insulin content in Wistar fatty rats at 5 and 14 wk of age did not increase more than those of their lean littermates at the corresponding ages and were therefore significantly lower than in Zucker fatty rats, which had a higher grade of hyperinsulinemia at 14 wk of age. The pplmRNA level in Wistar fatty rats at 14 wk of age was found to be 41% of that of Zucker fatty rats at corresponding age (P < 0.001). Increased pplmRNA level in association with hyperinsulinemia in VMHlesioned and Zucker fatty rats suggests that the activation of insulin-gene expression for adaptation to a large demand for insulin is common to obesity without diabetes (both experimental and genetic). Furthermore, the inability to augment pplmRNA level to meet a large demand for insulin in Wistar fatty rats is associated with the occurrence of diabetes. These findings suggest that obesity induces diabetes only when a primary defect exists in the β-cell.
Recognition of Common Islet Antigen by Autoantibodies From NOD Mice and Humans With IDDM
Authors: Karounos Dennis G , Thomas James W
Published: September 2013

Previous studies showed that islet cell autoantibodies are present at the onset of insulin-dependent diabetes mellitus (IDDM) in humans and in rodent models of this disease. The targets of these antibodies are not well characterized. Using an immunoblot assay on protein extracts from rat insulinoma (RIN) cells (RINmSF), we showed that serums from nonobese diabetic (NOD) mice bind to a 52,000-Mr islet cell antigen. Nondiabetic NON mice do not have antibodies to this antigen. The NOD and NON serums also contained antibodies to salivary gland proteins. Analysis of the tissue distribution of the 52,000-Mr antigen revealed that it is present in purified RINm5F membranes but is not found in other endocrine or nonendocrine tissues. Autoantibodies to an antigen of similar molecular weight are detected in 29% of human IDDM serums. To determine whether the autoantibodies from mouse and human serums bind the same antigen, two-dimensional immunoblots were carried out. The 52,000-Mr protein isoforms appeared identical when probed with NOD and human IDDM serums. We conclude that serums from NOD mice and some humans with IDDM contain similar autoantibodies to a 52,000-Mr RINmSF cell-specific membrane protein. The presence of autoantibodies to this 52,000-Mr islet cell protein at the onset of the disease suggests that it may be an important antigen in IDDM.
Normal Coding Sequence of Insulin Gene in Pima Indians and Nauruans, Two Groups With Highest Prevalence of Type II Diabetes
Authors: Raben Nina , Barbetti Fabrizio , Cama Alessandro , Lesniak Maxine A , Lillioja Stephen , Zimmet Paul , Serjeantson Sue W , Taylor Simeon I , Roth Jesse
Published: September 2013

The nucleotide sequence of the insulin gene was determined in American Pima Indians and Micronesian Nauruans, two populations in whom the prevalence of non-insulin-dependent (type II) diabetes mellitus is the highest in the world. The insulin gene was amplified by the polymerase chain reaction to generate single-stranded DNA suitable for direct sequencing. The nucleotide sequences of the coding and adjacent regions of the insulin gene in six Pima Indians and two Nauruans with type II diabetes were identical to previously published insulin gene sequences of nondiabetic subjects.
Insulin Secretory Response to Secretagogues by Perifused Islets From Chronically Glucose-Infused Rats
Authors: Bedoya Francisco J , Jeanrenaud Bernard
Published: September 2013

Perifused islets from rats infused for 7 days with 40% glucose exhibited an altered secretory response to selected stimuli. Both phases of insulin release were blunted when 20 mM L-leucine was tested; the secretory response to a subsequent leucine stimulation was also blunted compared with the control group. The ability of 20 mM α-ketoisocaproate to stimulate the release of insulin was also greatly diminished in islets from glucose-infused rats. The secretory response to 50 μM tolbutamide plus 7 mM glucose by perifused islets from glucose-infused rats was 45% lower than in the control group. In addition, the response to a subsequent 10 mM glucose stimulation was lost. On the other hand, islets from glucose-infused rats responded to 20 μM forskolin plus 16.7 mM glucose with no significant change in the amount of insulin released during both phases of stimulation compared with the control group. The response to 100 nM phorbol 12-mirystate 13-acetate was 3.1-fold higher in islets from glucose-infused compared with saline-infused rats. The finding that chronic infusions of glucose lead to selective impairment of the secretory response to fuel stimuli and agents such as tolbutamide that act on metabolically regulated K+ channels gives support to the notion that alterations in the generation of metabolic coupling signals might be involved in the phenomenon described here.
Immunolocalization of Glucose Transporter GLUT4 Within Human Skeletal Muscle
Authors: Friedman Jacob E , Dudek Ronald W , Whitehead Dan S , Downes Deborah L , Frisell Wilhelm R , Caro José F , Dohm G Lynis
Published: September 2013

To investigate the cellular and subcellular distributioi of glucose transporters in skeletal muscle, the gluco transporter isoform GLUT4 was localized in human muscle by electron microscopy via immunogold labeling with monoclonal (1F8) or COOH-terminal peptide polyclonal (ECU4) antibody and in isolated rat membranes by Western blot. There was no labeling c GLUT4 in endothelial cells of the capillaries. There also was no labeling of GLUT4 on the surface plasms membrane (sarcolemma) under either basal or insulin-stimulated conditions. Specific labeling for GLUT4 was clearly observed in two compartments: within the trie (on terminal cisternae and transverse tubules) and on an intracellular compartment, possibly sarcoplasmic tubules. Isolated triad membranes from rat muscle al contained substantial quantities of GLUT4 transporte but there was no detectable GLUT4 protein in isolate sarcolemmal membranes. These data suggest a possible mechanism that involves glucose transport across the muscle cell at the transverse tubule membrane, not the sarcolemma.
Importance of Hepatic Glucoreceptors in Sympathoadrenal Response to Hypoglycemia
Authors: Donovan Casey M , Halter Jeffrey B , Bergman Richard N
Published: September 2013

To ascertain whether hepatic glucoreceptors are important to hypoglycemic counterregulation, a localized euglycemic clamp was employed across the liver during general hypoglycemia. Dogs were infused peripherally with insulin (18–21 pmol · kg−1 · min−1) for 150 min to induce systemic hypoglycemia. During the liver-clamp (LC) protocol, glucose was infused via the portal vein to maintain euglycemia at the liver. In control experiments, i.e., matched infusion (Ml), glucose was infused peripherally at a rate determined to yield similar arterial glycemia levels in the two protocols. Arterial glucose concentrations were not different between protocols during the final hour of insulin infusion (3.26 ± 0.21 and 3.25 ± 0.21 mM during LC and MI, respectively; P = 0.91). Calculated hepatic glucose concentrations during the same period were significantly higher for LC (5.22 ± 0.23 mM) than for MI (3.25 ± 0.21 mM). During MI, both epinephrine and norepinephrine rose significantly from basal values of 562 ± 87 pM and 1.21 ± 0.19 nM to plateaus of 3691 ± 1097 pM (P = 0.0001) and 2.38 ± 0.35 nM (P = 0.0002), respectively. However, during LC, the elevation in epinephrine was suppressed by 42 ± 8% (P = 0.015) relative to MI. Six of seven animals demonstrated a suppression in the norepinephrine response, averaging 32 ± 13% (NS, P = 0.068). The glucagon response to hypoglycemia was unaffected by the level of hepatic glycemia. Hepatic hypoglycemia is essential to produce the full sympathoadrenal response to insulin-induced hypoglycemia.
Resistance of Growth Hormone Secretion to Somatostatin in Men With Type I Diabetes Mellitus
Authors: Cohen Robert M , Abplanalp William A
Published: September 2013

The effect of continuous infusions of somatostatin (SRIF) on growth hormone (GH) secretion induced by GH-releasing hormone (GHRH) bolus was compared in a dose-response manner between diabetic subjects in poor glycemic control and nondiabetic subjects to address the hypothesis that altered pituitary responsiveness to SRIF contributes to the hypersecretion of GH in diabetes mellitus in humans. Studies were conducted with a modification of the euglycemic clamp technique to minimize fluctuations in glucose and insulin. Suppression of GHRH-induced GH secretion was demonstrable in diabetic subjects only at a SRIF dose 15-fold higher than that at which suppression could be detected in nondiabetic subjects. The calculated 50% inhibitory dose (ID50) in diabetic subjects was 4-fold higher than that in nondiabetic subjects (P = 0.03). In diabetic subjects after 2 wk of intensive insulin management, the change in the dose-response curve persisted despite significant decrements in glycosylated hemoglobin and increments in plasma insulinlike growth factor I. The increment in plasma SRIF predicted at the SRIF ID50 from concentrations measured during the SRIF infusions in nondiabetic subjects would result in hypophyseal portal SRIF concentrations in the physiological range reported in recent animal studies, whereas those for the ID50 in diabetic subjects would be ∼1.5–2.5 times the upper limit of that range. These studies indicate that pituitary resistance to the action of SRIF occurs in men with insulin-dependent (type I) diabetes at physiological concentrations of the hormone and is therefore highly likely to contribute to the hypersecretion of GH in diabetes.
Liposomal Delivery of Purified Heat Shock Protein hsp70 Into Rat Pancreatic Islets as Protection Against Interleukin 1β–Induced Impaired β-Cell Function
Authors: Margulis Boris A , Sandler Stellan , Eizirik Décio L , Welsh Nils , Welsh Michael
Published: September 2013

Recently it has been demonstrated that heat shock protein 70 (hsp70) is induced in pancreatic islet cells during prolonged exposure to interleukin 1β (IL-1β). It is unclear whether this represents a cellular defense against the noxious action of IL-1β or whether hsp70 is involved in the suppressive action of the cytokine. To assess the role for hsp70 in isolated islets exposed to IL-1β, hsp70 was purified and introduced into cells of isolated rat pancreatic islets via the liposome technique. Delivery of hsp70 was efficient according to immunoblot analysis, but delivered hsp70 disappeared within 16 h. Hsp70-containing liposomes did not affect protein synthesis, insulin secretion, or islet insulin mRNA content. However, when hsp70 liposome–incubated islets were further exposed to IL-1β (25 U/ml) for 16 h, these islets released more insulin in response to glucose stimulation and contained more insulin mRNA than islets incubated with control liposomes and subsequently exposed to the cytokine. No protective effect of liposomes containing bovine serum albumin or ovalbumin were observed. We conclude that hsp70 may protect against IL-1β–induced impairment of pancreatic β-cell function.