bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorylation and Activity of Na+/H+ Exchanger Isoform 1 of Immortalized Lymphoblasts in Diabetic Nephropathy
Authors: Sweeney Frank P , Siczkowski Martin , Davies Joan E , Quinn Paulene A , McDonald John , Krolewski Bozena , Krolewski Andrzej S , Ng Leong L
Published: September 2013

In both essential hypertension and diabetic nephropathy (DN), the ubiquitous cellular Na+/H+ exchanger (NHE) exhibits altered kinetics with increased transport activity. The mechanism for this phenotype and its dependence on the presence of serum are unknown, but increased lymphoblast NHE activity in DN has been attributed to a defect in post-translational processing of NHE-1 rather than an increased cellular exchanger number. Phosphorylation of NHE-1 has been proposed to play a role in its activation in a variety of cell models. We have examined, therefore, the role of NHE-1 phosphorylation and the effect of serum in determining the increased NHE-1 activity in lymphoblasts from patients with DN. Cells from these patients exhibited increased NHE activity in the presence and absence of fetal calf serum (range 42–59%, P < 0.005, analysis of variance) and an increased proliferation rate (P < 0.01) when compared with cells from both normoalbuminuric diabetic patients and non-diabetic control subjects. However, NHE-1 abundance was very similar among all groups in the presence and absence of serum, indicating that increased NHE activity in cells of nephropathy patients was due to an increased turnover number. This nephropathy phenotype was not accompanied by an increased net phosphorylation of NHE-1 in the presence or absence of serum. Our findings suggest that increased NHE-1 activity in cells of DN patients is independent of the presence of serum and is not attributable to altered NHE-1 phosphorylation. Additional post-translational mechanisms for activation of NHE-1, therefore, may be involved.
Cloning, Functional Expression, and Chromosomal Localization of the Human Pancreatic Islet Glucose-Dependent Insulinotropic Polypeptide Receptor
Authors: Gremlich Sandrine , Porret Andrée , Hani El Habib , Cherif Dorra , Vionnet Nathalie , Froguel Philippe , Thorens Bernard
Published: September 2013

Glucose-dependent insulinotropic polypeptide (GIP) is a hormone secreted by the endocrine K-cells from the duodenum that stimulates glucose-induced insulin secretion. Here, we present the molecular characterization of the human pancreatic islet GIP receptor. cDNA clones for the GIP receptor were isolated from a human pancreatic islet cDNA library. They encoded two different forms of the receptor, which differed by a 27–amino acid insertion in the COOH-terminal cytoplasmic tail. The receptor protein sequence was 81% identical to that of the rat GIP receptor. When expressed in Chinese hamster lung fibroblasts, both forms of the receptor displayed high-affinity binding for GIP (180 and 600 µmol/l). GIP binding was displaced by <20% by 1 µmol/l glucagon, glucagon-like peptide (GLP-I)(7–36) amide, vasoactive intestinal peptide, and secretin. However exendin-4 and exendin-(9–39) at 1 μumol/l displaced binding by ∼70 and ∼100% at 10 µmol/l. GIP binding to both forms of the receptor induced a dose-dependent increase in intracellular cAMP levels (EC50 values of 0.6–0.8 µmol/l) but no elevation of cytoplasmic calcium concentrations. Interestingly, both exendin-4 and exendin-(9–39) were antagonists of the receptor, inhibiting GIP-induced cAMP formation by up to 60% when present at a concentration of 10 μmol/l. Finally, the physical and genetic chromosomal localization of the receptor gene was determined to be on 19q13.3, close to the ApoC2 gene. These data will help study the physiology and pathophysiology of the human GIP receptor.
In Situ Hybridization of Interleukin 6 in Diabetic Nephropathy
Authors: Suzuki Daisuke , Miyazaki Masanobu , Naka Raita , Koji Takehiko , Yagame Mitsunori , Jinde Kiichiro , Endoh Masayuki , Nomoto Yasuo , Sakai Hideto
Published: September 2013

Increased mesangial expansion is one of the most characteristic histological changes in diabetic nephropathy (DN). Although the pathogenesis of DN remains unclear, recent studies associate interleukin (IL) 6 with mesangial proliferative glomerulonephritis. To elucidate the expression and localization of IL-6 mRNA in renal tissues of patients with DN, a high-resolution in situ hybridization using digoxigenin-labeled oligonucleotide was performed. Patients were divided into three groups based on light microscopy findings: mild (group 1), moderate (group 2), and severe (group 3) mesangial expansion. The relationship between the expression of IL-6 mRNA and the degree of glomerular mesangial expansion in DN was examined. Individual cells positive for IL-6 mRNA were observed in glomeruli. These cells were mesangial cells, glomerular epithelial cells, and Bowman's capsule. The signal intensity was strongest in tissues from group 2 but was weak in those from groups 1 and 3. Most cells in the area of mesangial proliferation were strongly stained for IL-6 mRNA, and few positive cells were found in the Kimmelstiel-Wilson nodular lesion. In the interstitium, some tubules, particularly atrophic tubules, and some infiltrating cells were positively stained for IL-6 mRNA. The interstitial expression of IL-6 mRNA correlated significantly with the degree of interstitial injury and was remarkable in tissues from groups 2 and 3. We conclude that IL-6 mRNA is expressed by glomerular resident cells and interstitial cells in the renal tissue of patients with DN and that its expression may be associated with mesangial proliferation and may be involved in the tissue injury of DN.
Effects of a 48-h Fat Infusion on Insulin Secretion and Glucose Utilization
Authors: Boden Guenther , Chen Xinhua , Rosner Joel , Barton Michael
Published: September 2013

To determine the effects of prolonged elevation of plasma free fatty acids (FFAs) on insulin secretion, we infused Liposyn II (4.3 μmol · kg−1 · min−1) plus heparin (0.4 U · kg−1 · min−1) intravenously into six healthy volunteers for 48 h. Another six volunteers received saline infusions and served as control subjects. In all 12 subjects (11 men and 1 woman), plasma glucose was clamped at ∼8.6 mmol/l. Liposyn/heparin infusion resulted in a 9.4-fold increase in plasma FFA concentration (from 132 to 1,237 μmol/l), a 46% increase in insulin secretion rates (from 241 to 352 pmol/min, P < 0.05) (determined by deconvolution of plasma C-peptide concentration), and a 30% decrease, during the initial 24 h, in the rate of glucose infusion needed to maintain hyperglycemia (from 55.5 to 39.1 μmol · kg−1 · min−1, P < 0.02). This decrease disappeared during the second 24 h. In summary, we found that physiologically elevated plasma FFAs 1) potentiated glucose-stimulated insulin secretion for 48 h and 2) initially caused peripheral insulin resistance that disappeared during the 2nd day, probably as a result of elevated circulating insulin levels. We conclude that in healthy volunteers under hyperglycemic conditions, fat infusion produced insulin resistance that was compensated for after ∼24 h by persistent hypersecretion of insulin.
Linkage Analyses of the MODY3 Locus on Chromosome 12q With Late-Onset NIDDM
Authors: Lesage Suzanne , Hani El Habib , Philippi Anne , Vaxillaire Martine , Hager Jörg , Passa Philippe , Demenais Florence , Froguel Philippe , Vionnet Nathalie
Published: September 2013

Non-insulin-dependent diabetes mellitus (NIDDM) is a clinically and genetically heterogeneous disorder. Maturity-onset diabetes of the young (MODY), an autosomal dominant form of NIDDM, has been used as a model for genetic studies of NIDDM. We recently reported linkage between markers on chromosome 12q and diabetes in 25% of our French MODY families. To evaluate if this gene is also implicated in late-onset NIDDM, we performed linkage studies between two markers of the MODY region and diabetes in 172 families with late-onset NIDDM. Both parametric and nonparametric methods were used in a total of 600 affected sib-pairs. Linkage was rejected in this population by all methods, implying that the MODY gene on chromosome 12q is not a major gene for late-onset NIDDM in this population. However, we cannot exclude a modifying role in a polygenic disorder or an important role in some families.
Characterization of Insulin Resistance and NIDDM in Transgenic Mice With Reduced Brown Fat
Authors: Hamann Andreas , Benecke Heike , Marchand-Brustel Yannick Le , Susulic Vedrana S , Lowell Bradford B , Flier Jeffrey S
Published: September 2013

We recently created a new model of murine obesity through transgenic ablation of brown adipose tissue (BAT) using a tissue-specific toxigene (6). The goal of the present study was to further define the altered glucose homeostasis and insulin resistance in these transgenic animals. Despite an ∼30% increase in total body lipid, no abnormalities were observed in 6-week-old transgenic animals. At the age of 22–26 weeks, marked obesity in transgenic mice was associated with significant increases in blood glucose and plasma insulin levels and an abnormal response to both intraperitoneal glucose and insulin tolerance tests. Glucose transport in soleus muscle was reduced, with the response to insulin stimulation blunted by up to 85% in males and 55% in females. The total number of insulin receptors was decreased by 36% in muscle and 59% in adipose tissue of transgenic animals. Insulin receptor tyrosine kinase activity, which was assessed following maximal insulin stimulation in vivo, was reduced in transgenic animals by 59% in muscle and 56% in fat. GLUT4 mRNA and protein was unchanged in muscle of transgenic animals compared with in that of controls but was significantly reduced in adipose tissue. In conclusion, primary BAT deficiency results in the development of glucose intolerance or diabetes and severe insulin resistance with both receptor and postreceptor components. These animals should be a useful model for studies of obesity-linked diabetes and insulin resistance and related complications.
Residual β-Cell Function and HLA-A24 in IDDM: Markers of Glycemic Control and Subsequent Development of Diabetic Retinopathy
Authors: Nakanishi Koji , Kobayashi Tetsuro , Inoko Hidetoshi , Tsuji Kimiyoshi , Murase Toshio , Kosaka Kinori
Published: September 2013

To identify risk factors for diabetic retinopathy in insulin-dependent diabetes mellitus (IDDM), we studied the relationships among residual β-cell function, human leukocyte antigen (HLA), long-term glycemic control, and development of diabetic retinopathy in 128 IDDM patients. Residual β-cell function was assessed by serum C-peptide immunoreactivity (CPR) response to a 100-g oral glucose load (ΔCPR). The patients were stratified into three groups: those with ΔCPR of <0.033 nmol/1 (group 1, n = 50), those with ΔCPR of 0.033–0.1 nmol/1 (group 2, n = 38), and those with ΔCPR of > 0.1 nmol/1 (group 3, n = 40). The cumulative incidence rate of background retinopathy was higher in the order of groups 1, 2, and 3 (P = 0.032). Group 1 progressed to preproliferative retinopathy at an earlier stage than did groups 2 and 3 combined (P = 0.028). Further progression to proliferative retinopathy tended to be earlier in group 1 than in groups 2 and 3 combined (P = 0.083). The mean HbA1c value rose from 9.01 ± 1.06% (mean ± SD) in group 3 to 9.75 ± 0.79% in group 2 to 10.48 ± 1.12% in group 1 (P <0.0001). In group 1, 89.6% of the patients had HLA-A24, whereas 50 and 43.6% of the patients had this antigen in groups 2 and 3 respectively (P <0.0001). In Cox's proportional hazards model, both serum CPR response and mean HbA1c value were identified as independent risk factors for development of diabetic retinopathy after adjusting for other potential risk factors. These results indicate that complete loss of β-cell function, which is associated with HLA-A24, predicts earlier occurrence of diabetic retinopathy through metabolic control.
ICA512 Autoantibody Radioassay
Authors: Gianani Roberto , Rabin Daniel U , Verge Charles F , Yu Liping , Babu Sunanda R , Pietropaolo Massimo , Eisenbarth George S
Published: September 2013

As part of a general program of screening islet expression libraries we have identified a clone from a λgt11 human islet expression library that reacts with human diabetic sera and, upon sequencing, was determined to be the neuroendocrine islet autoantigen ICA512 (islet cell antigen 512). In the current communication, we describe the development of a radioassay for autoantibodies to ICA-512 (ICA512AA) using in vitro transcribed and translated protein for production of labeled antigen. Our initial results indicate that this radioassay is significantly more sensitive than the enzyme-linked immunosorbant assay, which uses a COOH-terminal fragment of ICA512. The ICA512AA radioassay uses a 96-well format with membrane separation of antibody bound from free antigen and should be readily adaptable to automated large-scale screening. Only 7 μl of serum is required for triplicate determinations. In order to determine the specificity and sensitivity of this assay and estimate its positive predictive value, we have studied 42 new-onset diabetic patients, 33 first-degree relatives of diabetic patients followed to diabetes, 694 islet cell antibody-negative (ICA–) relatives, and 205 normal control subjects. Thirty-eight percent of new-onset patients and 48% of relatives followed to diabetes express autoantibodies to ICA512 exceeding the 99th percentile of the normal control subjects. In contrast, only 1.4% of ICA– first-degree relatives were positive for ICA512 autoantibodies. By using three radioassays for islet autoantibodies against insulin, glutamic acid decarboxylase 65 (GAD65), and ICA512, 100% of the prediabetic sera we have studied have been shown to express antibodies to at least one antigen, and the majority (88%, 27 of 31) express two or more. ICA512 autoantibodies provide a specific marker for type I diabetes and, in combination with antibodies to GAD65 and insulin, should facilitate the prediction of type I diabetes.
Hyperglycemia Activates Glucose Transport in Rat Skeletal Muscle Via a Ca2+-Dependent Mechanism
Authors: Nolte Lorraine A , Rincón Jorge , Wahlström Erica Odegaard , Craig Bruce W , Zierath Juleen R , Wallberg-Henriksson Harriet
Published: September 2013

We investigated the acute effect of hyperglycemia on 3-O-methylglucose transport in isolated rat epitrochlearis muscles. High levels of glucose (20 mmol/1) induced an ∼ twofold increase in the rate of glucose transport when compared with muscles exposed to a low level of glucose (8 mmol/1) (P < 0.001). The hyperglycemic effect was additive to the effects of both insulin and exercise on the glucose transport rates. Dantrolene (25 αmol/l), a potent inhibitor of Ca2+ release from the sarcoplasmic reticulum, blocked the ability of hyperglycemia to increase glucose transport by 73% (P < 0.01). Although dantrolene had no effect on the non-insulin-stimulated or the insulin-stimulated glucose transport rates during normoglycemic conditions, the effect of exercise was completely blocked in the presence of dantrolene (P < 0.01). Inhibition of phosphatidylinositol (PI) 3-kinase by wortmannin (500 nmol/l) had no effect on the activation of glucose transport by hyperglycemia, whereas the insulin-stimulated glucose transport was completely abolished (P < 0.001). These findings suggest that hyperglycemia activates glucose transport by a Ca2+- dependent pathway. The signaling system for this Ca2+- dependent activation of glucose transport does not involve the activation of PI 3-kinase and is separate from the mass-action effect of glucose on glucose transport.
IgG Antibodies to Bovine Serum Albumin Are Not Increased in Children With IDDM
Authors: Ivarsson Sten-A , Månsson Majvi U L , Jakobsson Irene L
Published: September 2013

IgG antibodies to bovine serum albumin (BSA) were measured in 91 serum samples from children 4–17 years of age with newly diagnosed insulin-dependent diabetes mellitus (IDDM). A total of 80 healthy 12-year-old children served as control subjects. BSA antibody values >3 SDs were obtained in 6 IDDM patients and 3 control subjects (P = 0.50), and values >2 SDs were obtained in 12 IDDM patients and 4 control subjects (P = 0.11). In conclusion, IgG antibodies to BSA were not significantly increased at onset of diabetes.
Upregulation of Blood-Brain Barrier GLUT1 Glucose Transporter Protein and mRNA in Experimental Chronic Hypoglycemia
Authors: Kumagai Arno K , Kang Young-Sook , Boado Rubén J , Pardridge William M
Published: September 2013

An in vivo model of chronic hypoglycemia was used to investigate changes in blood-brain barrier(BBB) glucose transport activity and changes in the expression of GLUT1 mRNA and protein in brain microvasculature occurring as an adaptive response to low circulating glucose levels. Chronic hypoglycemia was induced in rats by constant infusion of insulin via osmotic minipumps; control animals received infusions of saline. The criterion for chronic hypoglycemia was an average blood glucose concentration of <2.3 mmol/l (42 mg/dl) after 5 days. The average blood glucose concentration at the end of the experimental period in the rats selected for study was 2.0 ± 0.1 mmol/l (36 ± 1 mg/dl) vs. 4.9 ± 0.1 mmol/l (88 ± 1 mg/dl) in the controls. Internal carotid artery perfusion studies demonstrated an increase in the BBB permeability-surface area (PS) product of 40% (P < 0.0005) in the chronically hypoglycemic animals as compared with controls. Western blotting of solubilized isolated brain capillaries demonstrated a 51% increase (P < 0.05) in immunoreactive BBB GLUT1 in the chronically hypoglycemic rats, and Northern blotting of whole-brain poly(A+) mRNA revealed a 50% increase in the GLUT1-to-actin ratio in the insulin-treated group (P < 0.05). Northern blotting analysis of microvessel-depleted total brain poly(A+) showed that the increase in GLUT1 mRNA in the chronically hypoglycemic rats was restricted to the BBB. The present study demonstrates increased expression of GLUT1 mRNA and protein at the BBB in chronic hypoglycemia and suggests that this increase is responsible for the compensatory increase in BBB glucose transport activity that occurs with chronically low circulating blood glucose levels.
Enteral Enhancement of Glucose Disposition by Both Insulin-Dependent and Insulin-Independent Processes: A Physiological Role of Glucagon-Like Peptide I
Authors: D'Alessio David A , Prigeon Ronald L , Ensinck John W
Published: September 2013

Glucagon-like peptide I (GLP-I)(7–36) amide is secreted by intestinal L-cells in response to food ingestion. GLP-I is a potent insulin secretagogue and also inhibits glucagon release. Inaddition, when given to humans in pharmacological amounts, GLP-I increases glucose disposal independent of its effects on islet hormone secretion. To test the hypothesis that this extrapancreatic effect of GLP-I on glucose disposition is present at physiological levels of GLP-I, we performed intravenous glucose tolerance tests (IVGTTs) 1 h after the following interventions: 1) the ingestion of 50 g fat to stimulate GLP-I secretion or the ingestion of water as a control and 2) infusion of GLP-I to attain physiological levels or a control infusion of saline. The results of the IVGTTs were analyzed using the minimal model technique to determine the insulin sensitivity index (SI) and indexes of insulin-independent glucose disposition, glucose effectiveness at basal insulin (SG), and glucose effectiveness at zero insulin (GEZI), as wellas the glucose disappearance constant (kg) and the acute insulin response to glucose (AIRg). These parameters were compared between conditions of elevated circulating GLP-I and control conditions. After ingestion of fat and infusion of synthetic hormone, plasma GLP-I increased to similar levels; GLP-I did not change with water ingestion or saline infusion. Elevated levels of GLP-I, whether from fat ingestion or exogenous infusion, caused increased glucose disappearance (kg: fat versus water 2.67 ± 0.2 vs. 1.72 ± 0.2, P < 0.001; GLP-I versus saline 2.42 ± 0.2 vs. 1.96 ± 0.2 %/min, P = 0.045), insulin secretion (AIRg: fat versus water 427 ± 50 vs. 284 ± 41, P = 0.001; GLP-I versus saline 376 ± 65 vs. 258 ± 16 pmol/1, P = 0.03), and glucose effectiveness (SG: fat versus water 2.5 ± 0.1 vs. 1.8 ± 0.2, P = 0.001; GLP-I versus saline 2.5 ± 0.2 vs. 1.8 ± 0.2%/min, P = 0.014; GEZI: fat versus water 1.9 ± 0.2 vs. 1.3 ± 0.2%/min, P = 0.003; GLP-I versus saline 1.9 ± 0.2 vs. 1.3 ± 0.2,P = 0.006) but no difference in insulin sensitivity. These results suggestthat GLP-I, released after meals, promotes glucose assimilation both by augmenting insulin secretion and through a separate effect to increase glucose uptake and/or inhibit hepatic glucose output.
Positional Cloning Works!: Identification of Genes That Cause IDDM
Authors: Rich Stephen S
Published: September 2013

The strategy of positional cloning has been highly successful in identifying a number of single gene disorders that exhibit clear Mendelian patterns of inheritance. Positional cloning of insulin-dependent diabetes mellitus (IDDM) has been assisted by the expansion of molecular genetic tools and highly informative markers, so that new IDDM susceptibility genes are being uncovered. The ultimate characterization of IDDM susceptibility, including the manner in which the individual genes interact to determine the genetic component of susceptibility, may be hindered by the complexity of the disease itself. Recent developments in analytic and experimental genetics have renewed enthusiasm in the use of identity by descent (state) methods that use affected relatives (sib pairs) rather than pedigrees as a fundamental tool of gene mapping. Given the relative position of IDDM susceptibility genes, major hurdles in understanding the roles of the identified genes in defining genetic susceptibility as well as their function lie ahead.
Bedtime Insulin/Daytime Glipizide: Effective Therapy for Sulfonylurea Failures in NIDDM
Authors: Shank Myron L , Prato Stefano Del , DeFronzo Ralph A
Published: September 2013

Bedtime insulin (BI)/daytime sulfonylurea (DSU) therapy was studied double-blind in 30 non-insulin-dependent diabetes mellitus subjects in whom sulfonylurea (SU) therapy had failed. Subjects were switched to glipizide for 2 months (phase I) to confirm failure (fasting plasma glucose [FPG] 12.0 ± 0.4 mmol/1) and then randomly assigned into three groups: BI-DSU; BI-no DSU; and DSU-no BI. During phase II (3 months), the BI dose was fixed (20 U/1.73 m2, low-dose). In phase III (3 months), BI was titrated up (high-dose) to achieve good control or until hypoglycemie symptoms prevented further dose increases. In phase IV (6 months), 25 of the 30 original subjects received open-labeled, high-dose BI-DSU. Low-dose BI-DSU markedly reduced FPG (13.6 ± 0.8 to 8.0 ± 0.6 mmol/1, P < 0.001), mean 24-h glucose (P < 0.001), HbA1c (8.9 ± 0.7 to 7.6 ± 0.3%, P = 0.07), and basal hepatic glucose production (HGP) (P < 0.005). A positive correlation (r = 0.69, P < 0.05) between the declines in FPG and HGP was observed. Neither low-dose BI alone nor DSU alone reduced FPG, mean 24-h glucose, HbA1c, or basal HGP. High-dose (40 ± 5 U/day) BI plus DSU further reduced the FPG (6.3 ± 0.6 mmoM), HbA1c (7.1 ± 0.3%), mean 24-h plasma glucose, and basal HGP (all P < 0.05 vs. phase II). High-dose BI alone (38 ± 4 U/day) improved FPG (P < 0.01 vs. phase II), mean 24-h plasma glucose (P < 0.005 vs. phase II), HbA1c (P < 0.05 vs. phase II), and basal HGP (P < 0.05 vs. phase I) to a degree similar to low-dose BI-DSU but less than high-dose BI-DSU. Regardless of prior treatment, FPG and HbA1c were controlled during phase IV. Weight gain during BI-DSU was largely attributable to reduced glucosuria. In conclusion, 1) both BI-DSU and BI alone improve glycemia in SU failure patients; 2) BI-DSU is superior to BI alone during both low- and high-dose BI; 3) the efficacy of BI is related to its suppression of basal HGP; and 4) good long-term glycemie control (up to 12 months) can be achieved with combined BI-DSU therapy.
Proinsulin as a Marker for the Development of NIDDM in Japanese-American Men
Authors: Kahn Steven E , Leonetti Donna L , Prigeon Ronald L , Boyko Edward J , Bergstrom Richard W , Fujimoto Wilfred Y
Published: September 2013

Disproportionate hyperproinsulinemia is one manifestation of the B-cell dysfunction observed in non-insulin-dependent diabetes mellitus (NIDDM), but it is unclear when this abnormality develops and whether it predicts the development of NIDDM. At baseline, measurements of proinsulin (PI) and immunoreactive insulin (IRI) levels were made in 87 second-generation Japanese-American men, a population at high risk for the subsequent development of NIDDM, and, by using World Health Organization criteria, subjects were categorized as having normal glucose tolerance (NGT; n = 49) or impaired glucose tolerance (IGT; n = 38). After a 5-year follow-up period, they were recategorized as NGT, IGT, or NIDDM using the same criteria. After 5 years, 16 subjects had developed NTODM, while 71 had NGT or IGT. Individuals who developed NIDDM were more obese at baseline, measured as intra-abdominal fat (IAF) area on computed tomography (P = 0.046) but did not differ in age from those who continued to have NGT or IGT. At baseline, subjects who subsequently developed NIDDM had higher fasting glucose (P = 0.0042), 2-h glucose (P = 0.0002), fasting C-peptide (P = 0.0011), and fasting PI levels (P = 0.0033) and disproportionate hyperproinsulinemia (P = 0.056) than those who continued to have NGT or IGT after 5 years of follow-up. NIDDM incidence was positively correlated with the absolute fasting PI level (relative odds = 2.35; P = 0.0025), even after adjustment for fasting IRI, IAF, and body mass index (relative odds = 2.17; P = 0.013). Because 12 of the 16 subjects who developed NTODM had IGT at baseline, the 38 IGT subjects were also examined separately. In this cohort, the same risk factors (fasting and 2-h glucose, fasting C-peptide, and fasting PI levels) were predictive for the development of NIDDM. We conclude that Japanese-American men who subsequently develop NIDDM have more IAF and increased glucose, C-peptide, and PI levels. These data suggest that alterations in PI may be a new marker for the subsequent development of NTODM.
Local Ventromedial Hypothalamus Glucopenia Triggers Counterregulatory Hormone Release
Authors: Borg Walter P , Sherwin Robert S , During Matthew J , Borg Monica A , Shulman Gerald I
Published: September 2013

To test the hypothesis that nuclei of the ventromedial hypothalamus (VMH) play a key role in the detection of counterregulatory responses to hypoglycemia, we delivered the glucopenic agent 2-deoxyglucose via bilaterally placed microdialysis probes into the VMH of conscious, chronically catheterized rats. The goal was to produce cellular glucopenia localized to the VMH. The volume of brain tissue exposed to 2-deoxyglucose was determined by adding [3H]2-deoxyglucose to the dialysate; its distribution in cerebral tissue was almost exclusively limited to the VMH. Rats with microdialysis probes placed into the frontal lobes served as a control group. Local perfusion of 2-deoxyglucose (but not glucose) into the VMH caused a prompt twofold increase in plasma glucose in association with a striking elevation of plasma glucagon (3.5-fold), epinephrine (30-fold), and norepinephrine (3.5-fold). No effect was seen when 2-deoxyglucose was delivered into the frontal lobes. We conclude that glucopenia localized to the VMH triggers the release of counterregulatory hormones that defend against hypoglycemia. Thus, the neurons that sense glucopenia may be situated in the VMH.
Mechanisms of Intracellular pH Regulation During Postischemic Reperfusion of Diabetic Rat Hearts
Authors: Khandoudi Nassirah , Bernard Monique , Cozzone Patrick , Feuvray Danielle
Published: September 2013

A marked decrease in the activity of the amiloride-sensitive Na+/H+ exchanger has been demonstrated in hearts from streptozotocin (STZ)-induced diabetic rats. The aim of this study was to investigate the contribution of other specific sarcolemmal transport mechanisms to intracellular pH (pHi) recovery upon reperfusion in STZ-induced diabetic rat hearts and their relation to recovery of ventricular function. Isovolumic rat hearts were submitted to a zero-flow ischemie period of 28 min at 37°C and then reperfused for 28 min. The time course of pHi decline during ischemia and of recovery on reperfusion was followed by means of 31P-labeled NMR. The perfusion buffers used were either HEPES or CO2/HCO3−. An HCO3−-dependent (amiloride-insensitive) mechanism contributed to pHi recovery after ischemia in the diabetic rat hearts. Even when the Na+/H+ exchanger was blocked by amiloride in nominally HCO3−-free solution, a rapid rise in pHi occurred during the first 3 min of reperfusion. The early rise in pHi was reduced by external lactate and inhibited by α-cyano-4-hydroxycinnamate. This suggested that a coupled H+-lactate efflux may be a major mechanism for acid extrusion in the initial stage of reperfusion. The observation of a higher functional recovery on reperfusion in diabetic hearts is in accordance with previous studies using HCO3− buffer. However, this study shows that a good recovery of function occurred even more rapidly in diabetic hearts receiving HEPES-buffered solution than in those receiving HCO3−-buffered solution. This suggests that the HCO3−-dependent mechanism of regulation may be depressed in diabetic rat hearts.
Rate of Weight Gain, Weight Fluctuation, and Incidence of NIDDM
Authors: Hanson Robert L , Narayan K M V , McCance David R , Pettitt David J , Jacobsson Lennart T H , Bennett Peter H , Knowler William C
Published: September 2013

The relationships of rate of weight gain and weight fluctuation to incidence of non-insulin-dependent diabetes mellitus (NIDDM) were examined in Pima Indians. The 1,458 subjects were participants in a prospective study with examinations approximately every 2 years. Rate of weight gain was defined as the slope of the regression line of weight with time for two or more consecutive examinations ≥2 years apart and weight fluctuation as the root-mean-square departure from this line for four examinations. Among men, incidence of NIDDM was strongly and significantly related to rate of weight gain (e.g., age-adjusted incidence = 56.7/1,000 person-years in those with weight gain ≥3 kg/year and 16.9/1,000 person-years for those losing weight [Ptrend < 0.01]). In women, weight gain was significantly related to diabetes incidence only in those who were not initially overweight (body mass index < 27.3 kg/m2). In contrast to the relationship with weight gain, weight fluctuation was not associated with incidence of diabetes in either sex. These findings suggest that weight control in overweight individuals may be a more effective strategy for prevention of NIDDM in men than in women, whereas prevention of obesity may prevent diabetes in both sexes. Concern about a diabetogenic effect of weight fluctuation should not deter weight-control efforts.
T-Cell Reactivity to β-Cell Membrane Antigens Associated With β-Cell Destruction in IDDM
Authors: Roep Bart O , Kallan Aram A , Duinkerken Gaby , Arden Susan D , Hutton John C , Bruining G Jan , De Vries René R P
Published: September 2013

Insulin-dependent diabetes mellitus (IDDM) results from a T-cell-mediated destruction of the insulin-producing β-cells. In this study, we designed a sensitive assay to detect and identify islet cell-reactive T-cells in patients with newly diagnosed IDDM. The relation between T-cell recognition of β-cell antigens with IDDM and the pathogenesis of the disease (the β-cell destruction process) was tested in a large group of IDDM patients and compared with T-cell responses in nondiabetic children with other chronic inflammations and in immunologically normal, age-matched control subjects. The results demonstrate that peripheral blood T-cells reacting with a β-cell membrane preparation enriched for insulin-secretory granule antigen were detectable in the majority of newly diagnosed IDDM patients (27 of 40 [67%]; mean stimulation index [SI] 37.0). Such reactivity was reduced postonset in IDDM patients proportionally to the duration of the disease (11 of 30 [37%]; mean SI 8.7). Nondiabetic age-matched control subjects showed no responses or moderate responses to the granule preparation (4 of 48 [8%]; mean SI 3.4). The magnitude of the T-cell response was significantly greater in newly diagnosed IDDM patients than in IDDM patients tested at least 2 years postonset (P < 0.001). Two children in remission for insulin dependency (so-called honeymoon period) displayed exceptionally high proliferative responses to insulin-secretory granules (mean SI 86.7). These results imply that T-cell recognition of insulin-secretory granule antigens is associated with IDDM and in particular with the immune-mediated process of β-cell destruction.
Evidence for a Major Gene Affecting Postchallenge Insulin Levels in Mexican-Americans
Authors: Mitchell Braxton D , Kammerer Candance M , Hixson James E , Atwood Larry D , Hackleman Susan , Blangero John , Haffner Steven M , Stern Michael P , MacCluer Jean W
Published: September 2013

Hyperinsulinemia, which is considered a hallmark of insulin resistance, precedes the development of non-insulin-dependent diabetes mellitus (NIDDM). Results of family and twin studies have shown that heredity influences insulin resistance and insulin levels. In Caucasian families ascertained through two or more NIDDM siblings, it has been reported that single genes with large effects, i.e., major genes, influence both fasting and 1-h postchallenge insulin levels. To determine whether a major gene affects 2-h postchallenge insulin levels in Mexican-Americans, we conducted segregation analyses using data collected on 527 pedigreed individuals from 27 families in San Antonio, TX. Probands for the families were randomly ascertained and all first-, second-, and third-degree relatives aged 16 years and older were invited to participate. Subjects received a 2-h oral glucose tolerance test, and diabetes was diagnosed according to World Health Organization criteria. We found that an autosomal dominant major gene best described the inheritance of 2-h insulin levels (ln-transformed) in these 27 families. Of the individuals in the population, 17% were homozygous for the 2-h low-insulin allele (back-transformed mean = 125 pmol/l) and 83% were heterozygous or homozygous for the 2-h high-insulin allele (back-transformed mean = 406 pmol/l). This major gene accounted for 31% of the variance in ln(2-h insulin levels) in this population. Using quantitative trait linkage analyses, we excluded tight linkage between this gene affecting 2-h insulin levels and three candidate loci for insulin levels: the insulin receptor gene, the low-density lipoprotein receptor gene, and the glucokinase gene. In addition, it is likely that this major gene is not linked to the fatty acid-binding protein gene, a gene that has previously been associated with insulin resistance through sib-pair analysis.
Factors Modifying the Risk of IDDM in Offspring of an IDDM Parent
Authors: El-Hashimy Mona , Angelico M Clara , Martin Blaise C , Krolewski Andrzej S , Warram James H
Published: September 2013

Offspring of mothers with insulin-dependent diabetes mellitus (IDDM) have a much lower risk of IDDM than do offspring of diabetic fathers, and this risk is particularly low for offspring born to diabetic mothers over the age of 25 years. To determine whether increasing maternal age also protects the offspring of IDDM fathers from IDDM, we surveyed 367 IDDM fathers (IDDM onset before age 35) who first came to the Joslin Clinic (Boston, MA) between 1945 and 1969. Of the 840 offspring of these men, IDDM developed in 28 before the age of 20, giving a cumulative risk of 5.1 ± 1.0% (means ± SE). Because this is similar to the result of our earlier study of IDDM fathers, the two groups were combined to give 1,084 offspring, 39 having IDDM (cumulative risk of IDDM 5.4 ± 0.9% by age 20), for comparison with our cohort of 1,391 offspring of 739 IDDM mothers. In that cohort, IDDM developed in 20 offspring before the age of 20 years, giving a cumulative risk of 2.1 ± 0.5%. The risk of diabetes in offspring was higher if the parent's IDDM was diagnosed before age 11 than if it was diagnosed later: 9.3 compared with 4.0% (P = 0.006) for the offspring of IDDM fathers and 2.7 compared with 1.8% for the offspring of IDDM mothers (P = 0.06). In the families in which the father's IDDM was diagnosed after age 11, a protective effect of maternal age ≥25, similar to that in families of IDDM mothers, seems to be present. However, in families in which the father's IDDM was diagnosed before age 11, the effect of maternal age seems to be in the opposite direction: the incidence rate doubled for the offspring born to nondiabetic mothers aged ≥25 years. In contrast, no effect of paternal age was found, regardless of which parent had IDDM. Our findings, although challenging to explain, have immediate implications for counseling families in which one parent has EDDM.
Renin Response to 12-Hydroxyeicosatetraenoic Acid Is Increased in Diabetic Rats
Authors: Antonipillai Indra , Jost-Vu Elke , Natarajan Rama , Nadler Jerry , Horton Richard
Published: September 2013

Eicosanoids (prostaglandins) can alter renin secretion and angiotensin (ANG) II action. We have studied the effects of both prostacyclin and a lipoxygenase (LO) product, 12-hydroxyeicosatetraenoic acid (12-HETE), on renin in normal and streptozotocin-induced diabetic rats. 12-HETE is not only a potent inhibitor of basal renin secretion but also a key mediator of ANG II-induced renin inhibition. We have also examined the effects of ANG II on 12-HETE formation in normal and diabetic animals. Both plasma (3.9 ± 0.9 vs. 0.8 ± 0.1 ng ANG I ç ml−1 + h−1, P < 0.01) and tissue (38 ± 6 vs. 21 ± 2 ng ANG I + mg tissue−1 + h−1, P < 0.05) renin activity levels were markedly reduced in diabetic animals. Iloprost (10−6 mol/l), a stable analog of prostacyclin, had similar stimulatory effects on renin secretion in both normal and diabetic tissues, but the response was enhanced by LO inhibition in diabetic tissue. 12-HETE (10−7 mol/l) had an exaggerated effect on renin inhibition in diabetic tissue (78 ± 2% normal vs. 65 ± 4% diabetic, P < 0.05). Similarly, ANG II (10−8 mol/l) inhibition of renin was significantly enhanced in diabetic rats (P < 0.001). However, ANG II did not produce an exaggerated increase in 12-HETE in diabetic renal tissue. Insulin reversed the inhibitory effects of ANG II on renin in normal rats, but it blunted the effect of ANG II in diabetic rats. These studies suggest that, while the capacity of renal cortical tissue to synthesize 12-HETE in response to ANG II is not altered, 12-HETE and ANG II actions are exaggerated in diabetes, and this may contribute to reduced renin production.
Analysis of the Hexokinase II Gene in Subjects With Insulin Resistance and NIDDM and Detection of a Gln142→His Substitution
Authors: Vidal-Puig Antonio , Printz Richard L , Stratton Irene M , Granner Daryl K , Moller David E
Published: September 2013

Hexokinase II (HKII) is the predominant hexokinase isozyme expressed in insulin-responsive tissues. Since defects involving glucose transport and/or its phosphorylation to glucose-6-phosphate are present in muscle of insulin-resistant humans, HKII should be viewed as a candidate gene for inherited insulin resistance and susceptibility to non-insulin-dependent diabetes mellitus (NIDDM). To investigate the prevalence of potential mutations in the gene encoding HKII, we used the polymerase chain reaction (PCR) to amplify each of the 18 exons of the HKII gene from genomic DNA derived from 59 subjects: 25 insulin-resistant probands with clinical features of the type A syndrome and 34 NIDDM subjects enrolled in the United Kingdom Prospective Study of Therapies of NIDDM (UKPDS) who represented the highest percentile of fasting hyperinsulinemia in the UKPDS population of 5,098 subjects. PCR products corresponding to individual HKII exons derived from each subject were screened for the presence of nucleotide variation using a sensitive nonradioactive single-strand conformation polymorphism (SSCP) protocol. Variant SSCP patterns indicative of genetic variation were detected only in PCR amplimers containing exons 4–s7, 10, 15, and 17. Direct sequencing of amplified DNA from individuals affected with variant SSCP patterns revealed the presence of the following silent polymorphisms: Asp251 (GAT/C) in exon 7 and Asn692 (AAT/C) in exon 15. SSCP variants detected in PCR products containing exons 5, 10, and 17 were due to single base substitutions in flanking intronic sequences. A polymorphic GGA repeat was identified within intron 5. A common missense mutation (Gin142→His) was detected in exon 4; however, the prevalence of this variant allele was not increased in NIDDM versus control subjects. We conclude that 1) His142 is a common variant HKII allele that is not associated with insulin resistance or NIDDM; 2) other mutations affecting the coding regions of the HKII gene are very uncommon in patients with severe insulin resistance or insulin-resistant patients with NIDDM; and 3) inherited defects involving the HKII structural gene are unlikely to contribute significantly to the genetic susceptibility to NIDDM.
Diabetes Induced with Low Doses of Streptozotocin is Mediated by Vβ8.2+ T-Cells
Authors: Herold Kevan C , Bloch Tamara N , Vezys Vaiva , Sun Qin
Published: September 2013

T-cells have been shown to cause insulitis and ultimately be responsible for the destruction of β-cells in animal models of insulin-dependent diabetes mellitus (IDDM). In one murine model, insulitis and hyperglycemia occur after administration of five low doses of streptozotocin (STZ) (multidose STZ-induced diabetes mellitus [MDSM]). Insulitis can first be identified in the islets after the final (fifth) daily dose of STZ is given. We have studied the T-cells that infiltrate the islets of Langerhans during the early stages of diabetes by preparing Southern blots of T-cell receptor (TCR) β-chain genes amplified by polymerase chain reaction (PCR) from islets from C57BL/KsJ mice given multiple doses of STZ. The relative abundance of TCR gene products in islets was compared with spleen cells stimulated with anti-CD3 monoclonal antibody (mAb). We found that after the fourth dose of STZ, there was a striking increase in the amount of V β 8.2 TCR gene product (37 ± 4% of total PCR signal) compared with T-cells in the spleen (9 ± 2%, P < 0.01), which increased further 2 days after the final dose of STZ (47 ± 5%, P < 0.001). We studied the heterogeneity of the size of the V β 8.2 TCR CDR3 region and found primarily products with only two lengths compared with a heterogeneous population in the spleen. Treatment with anti-Vβ8 mAb, but not anti-V β 9 and anti-V β 13 mAbs, prevented development of hyperglycemia (P < 0.0001) and insulitis (P < 0.0005) after STZ administration. We conclude that there is limited heterogeneity of the T-cell response that causes diabetes in MDSDM. A limited number of Vβ8.2+ cells are preferentially expanded in the islets in the early stages. Our results suggest that in this model of IDDM, a limited number of T-cells cause the disease.
Massive Isolation, Morphological and Functional Characterization, and Xenotransplantation of Bovine Pancreatic Islets
Authors: Marchetti Piero , Giannarelli Rosa , Cosimi Sabrina , Masiello Pellegrino , Coppelli Alberto , Viacava Paolo , Navalesi Renzo
Published: September 2013

The limited availability of human donors makes the search for alternative islet sources mandatory for future developments in pancreatic islet transplantation. In this study, we report on the massive isolation of bovine islets of proven in vitro and in vivo viability. The islets were prepared by collagenase digestion, sequential filtrations, and density-gradient purification by modifying a technique previously developed in our laboratory for the porcine pancreas. The prepurification yield was 2,743 ± 78 islet equivalents (IE)/g pancreas (mean ± SE), with a postpurification recovery of 78.7 ± 2.2%. Purity ranged from 80 to 90%. The histological and immunocytochemical studies demonstrated the identity and integrity of the islets with well-preserved insulin-, glucagon-, and somatostatin-containing cells. The morphological integrity of cultured bovine islets was demonstrated for up to 4 weeks from isolation. Insulin secretion from freshly isolated islets was similar at 3.3 mmol/l glucose (0.36 ± 0.06 pmol.IE−1 · min−1) and at 14 mmol/l glucose (0.42 ± 0.00 pmol.IE−1 · min−1), and it increased significantly (P < 0.01) at 25 mmol/l glucose (1.44 ± 0.12 pmol.IE−1 · min−1). Arginine, theophylline, and propionic acid increased insulin secretion from freshly isolated islets at 3.3 and 14 mmol/l glucose, but not at 25 mmol/l glucose. Islets cultured at 37 degrees C in CMRL 1066 culture medium for at least 10 days were shown to become responsive to a lower glucose concentration, as demonstrated by the significant increase of insulin release in response to 14 mmol/l glucose, when compared with basal secretion. This recovered responsivity to glucose was maintained after 4 weeks of culture. Reversal of hyperglycemia was obtained in nude mice with streptozotocin-induced diabetes, after transplantation of ∼ 1,500 bovine islets under the kidney capsule. Retrieval of the islet-bearing kidneys 28 days after implantation caused a return to hyperglycemia. Taken together, these results support the use of bovine islets as an alternative and readily available source of pancreatic endocrine tissue in transplantation studies.
Familial Relationships Between Obesity and NIDDM
Authors: Hanson Robert L , Pettitt David J , Bennett Peter H , Narayan K M V , Fernandes Richard , De Courten Maximilian , Knowler William C
Published: September 2013

Obesity and family history of diabetes are both risk factors for non-insulin-dependent diabetes mellitus (NIDDM), but it has been proposed that lean individuals with NIDDM have a greater load of diabetes susceptibility genes. If this is the case, one might expect a high prevalence of NIDDM in relatives of diabetic individuals with a low body mass index (BMI). Among Pima Indians participating in an epidemiological study, prevalence of NIDDM was evaluated in relation to BMI of a diabetic parent or to the average parental BMI when both parents had diabetes in 1,535 offspring from 547 families. Prevalence of NIDDM was also evaluated in relation to BMI of a randomly selected index diabetic sibling in 1,722 siblings from 721 families. NIDDM was diagnosed by an oral glucose tolerance test. Compared with offspring of diabetic parent(s) at the 25th percentile of BMI, the odds ratio (OR) for diabetes in offspring of diabetic parents at the 75th percentile was 0.6 (95% confidence interval [CI] 0.5–0.7), adjusted for age, sex, BMI in offspring, number of diabetic parents, and age at onset of diabetes and sex of the diabetic parent(s). In the analysis according to BMI in a diabetic sibling, the corresponding OR was 0.8 (95% CI 0.6–0.9). Risk ratios were only modestly higher when the analysis was restricted to relatives of subjects whose BMI had been determined before the onset of diabetes. NIDDM in the presence of a low BMI is more strongly familial than that at a higher BMI. inants of diabetes is present in leaner diabetic people, and it suggests that these determinants are largely separate from those that result in familial aggregation of obesity.