bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular Engineering and Gene Therapy Strategies for Insulin Replacement in Diabetes
Authors: Newgard Christopher B
Published: September 2013

In diabetes, insulin secretion is either completely absent (insulin-dependent diabetes mellitus [IDDM]) or inappropriately regulated (non-insulin-dependent diabetes mellitus [NIDDM]). In recent years, new insights into the molecular and biochemical mechanism(s) of fuel-mediated insulin release coupled with advances in gene transfer technology have led to the investigation of molecular strategies for replacement of normal insulin delivery function. Such initiatives have included attempts to engineer glucose-stimulated insulin secretion in cell lines that might serve as surrogates for islets in IDDM. The development of DNA virus gene transfer systems of remarkable efficiency also has suggested ways in which the beta-cell dysfunction of NIDDM might ultimately be repaired by gene therapy. The emerging work in these areas and implications for the future are summarized in this perspective.
Relationships Between Angiotensin I Converting Enzyme Gene Polymorphism, Plasma Levels, and Diabetic Retinal and Renal Complications
Authors: Marre Michel , Bernadet Pauline , Gallois Yves , Savagner Frederique , Guyene Tham-Tam , Hallab Magid , Cambien François , Passa Phillippe , Alhenc-Gelas François
Published: September 2013

Insulin-dependent diabetes mellitus (IDDM), cardiovascular morbidity, and vital prognosis are linked to diabetic nephropathy, which is probably determined by renal hemodynamic abnormalities and by a genetic predisposition. Angiotensin I converting enzyme (ACE) regulates systemic and renal circulations through angiotensin II formation and kinins metabolism. Plasma and cellular ACE levels are genetically determined; an insertion/deletion polymorphism of the ACE gene is strongly associated with ACE levels, subjects homozygote for insertion (genotype II) having the lowest plasma values. We studied the relationship between the ACE gene polymorphism or plasma levels and microcirculatory disorders of IDDM through two independent studies: one involved 57 subjects with or without diabetic retinopathy, and the other compared 62 IDDM subjects with diabetic nephropathy to 62 diabetic control subjects with the same characteristics (including retinopathy severity) but with normal kidney function. The ACE genotype distribution was not different in diabetic subjects with or without retinopathy and in a healthy population. Conversely, an imbalance of ACE genotype distribution, with a low proportion of II subjects, was observed in IDDM subjects with diabetic nephropathy compared with their control subjects (P = 0.006). Plasma ACE levels were mildly elevated in all diabetic groups, independently of retinopathy, but they were higher in subjects with nephropathy than in those without nephropathy (P = 0.0022). The II genotype of ACE gene is a marker for reduced risk for diabetic nephropathy.
PAI-1 and Factor VII Activity Are Higher in IDDM Patients With Microalbuminuria
Authors: Gruden Gabrieklla , Cavallo-Perin Paolo , Bazzan Mario , Stella Stefania , Vuolo Antonio , Pagano Gianfranco
Published: September 2013

Microalbuminuria is associated with an increased risk of cardiovascular disease (CVD) in insulin-dependent diabetes mellitus (IDDM) patients, but the pathophysiological basis of this association is not clear. To see whether or not hemostatic dysfunctions might contribute to explain this association, we measured tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), factor VII activity, plasma fibrinogen, and plasma endothelin-1 (ET-1) in 13 microalbuminuric (albumin excretion rate [AER], 20–200 μg/min) and in 13 comparable normoalbuminuric (< 20 μg/min) IDDM patients. t-PA and ET-1 were similar in the two groups, whereas PAI-1 activity (5.65 ± 1.92 vs. 0.85 ± 0.58 IU/ml, P < 0.05), factor VII (87.85 ± 4.94 vs. 76.54 ± 2.31%, P < 0.05), and plasma fibrinogen (3.38 ± 0.21 vs. 2.65 ± 0.13 g/l, P < 0.05) were significantly higher in microalbuminuric than in normoalbuminuric patients. Plasma fibrinogen was related to AER (r2 = 0.23, P < 0.05), whereas triglycerides and factor VII were related to PAI-1 (r2 = 0.39, P < 0.001 and r2 = 0.10, P < 0.05). These results suggest that microalbuminuria is associated with a hypercoagulative and hypofibrinolytic state. Hemostatic dysfunctions might be a pathogenetic link between microalbuminuria and CVD.
Multiple Low-Dose Streptozocin–induced Diabetes in NOD-scid/scid Mice in the Absence of Functional Lymphocytes
Authors: Gerling Ivan C , Friedman Harley , Greiner Dale L , Shultz Leonard D , Leiter Edward H
Published: September 2013

The murine severe combined immunodeficiency (scid) mutation was used to assess whether the diabetogenic effects of multiple low-dose streptozocin (MD-STZ) administration required the presence of functional T-cells. An STZ dose as low as 30 mg/kg body wt for 5 days induced hyperglycemia in young NOD/Lt-+/+ male mice, whereas a dose of 50 mg/kg for 5 days was required to elicit comparable hyperglycemia in C.B.-17-+/+ male mice. The greater NOD strain sensitivity was not a function of preexisting insulitis, because insulitis- and diabetes-free NOD male mice congenic for a diabetes-resistant major histocompatibility complex haplotype were equally susceptible to MD-STZ. This was confirmed in NOD-scid/scid and C.B.-17-scid/scid males. Both were completely insulitis-free, and despite the absence of functional T- cells and B-cells, both congenic stocks were as sensitive to MD-STZ as congenic +/+ controls. Indeed, MD-STZ-induced hyperglycemia in NOD-scid/scid male mice was significantly higher than in NOD/Lt-+/+ male mice. The NOD-scid/scid mouse as a recipient of adoptively transferred splenocytes clearly delineated a distinct pathogenesis of spontaneous insulin-dependent diabetes mellitus (IDDM) versus MD-STZ-induced hyperglycemia. Splenocytes from spontaneously diabetic NOD/Lt males, but not those from donors given MD-STZ, readily transferred IDDM, even when host beta-cells were sensitized by a single injection of STZ before adoptive transfer. We conclude that IDDM induced by MD-STZ is not mediated by T-cell- or B-cell-dependent autoimmune mechanisms in a fashion analogous to the spontaneous IDDM characteristic of NOD mice.
Detection of GAD65 Antibodies in Diabetes and Other Autoimmune Diseases Using a Simple Radioligand Assay
Authors: Petersen Jacob S , Hejnaæs Kim R , Moody Alister , Karlsen Allan E , Marshall Michael O , Høier-Madsen Mimi , Boel Esper , Michelsen Birgitte K , Dyrberg Thomas
Published: September 2013

Autoantibodies to glutamic acid decarboxylase (GAD) are frequent at or before the onset of insulin-dependent diabetes mellitus (IDDM). We have developed a simple, reproducible, and quantitative immunoprecipitation radioligand assay using as antigen in vitro transcribed and translated [35S]methionine-labeled human islet GAD65. By using this assay, 77% (77 of 100) of serum samples from recent-onset IDDM patients were positive for GAD65 antibodies compared with 4% (4 of 100) of serum samples from healthy control subjects. In competition analysis with unlabeled purified recombinant human islet GAD65, binding to tracer was inhibited in 74% (74 of 100) of the GAD65-positive IDDM serum samples compared with 2% of the control samples. The levels of GAD antibodies expressed as an index value relative to a standard serum, analyzed with or without competition, were almost identical (r = 0.991). The intra- and interassay variations of a positive control serum sample were 2.9 and 7.6%, respectively (n = 4). The frequency of GAD antibodies was significantly higher with IDDM onset before the age of 30 (80%, 59 of 74) than after the age of 30 (48%, 10 of 21) (P < 0.01). The prevalence of islet cell antibodies showed a similar pattern relative to age at onset. Because simultaneous occurrences of multiple autoimmune phenomena are common, we analyzed sera from patients with other autoimmune diseases. The frequency of GAD antibodies in sera positive for DNA autoantibodies (8% [2 of 25] and 4% [1 of 25] in competition analysis) or rheuma factor autoantibodies [12% (4 of 35) and 3% (1 of 35) in competition analysis] was not different from that in control samples. In contrast, in sera positive for ribonucleoprotein antibodies the frequency of GAD antibodies was significantly increased (73% [51 of 70] and 10% [7 of 70] in competition analysis [P < 0.025]). In conclusion, even large numbers of serum samples can now be tested for GAD65 antibodies in a relatively short time, allowing screening of individuals without a family history of IDDM for the presence of this marker.
Insulin Gene Transcription Is Decreased Rapidly by Lowering Glucose Concentrations in Rat Islet Cells
Authors: Philippe Jacques , Pacheco Isabelle , Meda Paolo
Published: September 2013

Glucose is the main physiological regulator of insulin biosynthesis and secretion. To exert an effect on biosynthesis, stimulatory concentrations of glucose act on insulin gene expression at both transcriptional and posttranscriptional levels. The relative importance of these two effects is controversial. Studies on the effect of decreasing glucose concentrations in vitro have been contradictory as to its rapidity and magnitude. We have investigated whether a decrease in glucose concentrations from a stimulatory (11 mM) to a nonstimulatory (2 mM) level regulates insulin gene expression in both isolated rat islets and INS-1 cells, an insulinoma-derived cell line that retains a number of the differentiation characteristics of native α-cells. We show that, in the presence of a nonstimulatory concentration of glucose, insulin mRNA levels decrease rapidly in both rat islets and INS-1 cells. Low glucose decreases insulin gene expression at the transcriptional level, and this effect is mediated by DNA sequences present within 254 base pairs of the 5′-flank of the rat insulin I gene. We conclude that lowering glucose from 11 to 2 mM decreases insulin mRNA rapidly by a transcriptional effect.
Tissue and Plasma Concentrations of Amidated and Glycine-Extended Glucagon-Like Peptide I in Humans
Authors: Ørskov Cathrine , Rabenhøj Lise , Wettergren André , Kofod Hans , Holst Jens J
Published: September 2013

Using specific radioimmunoassays, we studied the occurrence of amidated and glycine-extended glucagon-like peptide I (GLP-I) molecules in the human small intestine and pancreas and in the circulation system in response to a breakfast meal. Through gel permeation chromatography of extracts of the human pancreas (n = 5), we found that 71% of the GLP-I immunoreactivity eluted as a large molecule corresponding to the major proglucagon fragment, 24% corresponded to GLP-I 1–36 amide, and 5% to GLP-I 1–37. By gel permeation chromatography of extracts of human small intestine (n = 6), we found that all immunoreactivity eluted in one peak at the common elution position of the two insulin-releasing peptides, GLP-I 7–36 amide and GLP-I 7–37. Of the GLP-I immunoreactivity, 80% corresponded to GLP-I 7–36 amide and 20% to GLP-I 7–37. The mean concentrations of amidated GLP-I and glycine-extended GLP-I in fasting plasma were 7 ± 1 and 6 ± 1 pM, respectively (n = 6). In response to a breakfast meal, the concentration of amidated GLP-I rose significantly amounting to 41 ± 5 pM 90 min after the meal ingestion, whereas the concentration of glycine-extended GLP-I only rose slightly to a maximum of 10 ± 1 pM. Thus, both amidated and glycine-extended GLP-I molecules are produced in the small intestine and in the pancreas in humans. Both amidated and glycine-extended GLP-I are measurable in fasting plasma. The higher meal response of amidated GLP-I compared with glycine-extended GLP-I probably reflects the larger amount of amidated GLP-I produced in the tissues compared with glycine-extended GLP-I.
Regulation of Human Insulin Gene Transcription by Glucose, Epinephrine, and Somatostatin
Authors: Redmon J Bruce , Towle Howard C , Robertson R Paul
Published: September 2013

We observed in the HIT cell, a clonal insulin-secreting cell line, that epinephrine and somatostatin lower insulin mRNA levels and intracellular insulin content in addition to the well-recognized effect of these hormones to inhibit insulin secretion. To determine whether these inhibitory hormones might regulate insulin synthesis at the level of insulin gene transcription, we studied HIT cell expression of a human insulin-chloramphenicol acetyl transferase (CAT) reporter gene in the presence of glucose, epinephrine, and somatostatin. HIT cell expression of this human insulin-CAT reporter gene was responsive to glucose in a concentration-dependent manner, increasing threefold as the glucose concentration increased from 0.4 to 11 mM. Epinephrine significantly inhibited insulin-CAT reporter gene expression (61 ± 5% of control), an effect mediated specifically by the human insulin gene promoter/enhancer sequence. Somatostatin significantly inhibited expression of the human insulin-CAT reporter gene (65 ± 4% of control) and, to a lesser extent, expression of a control reporter gene, pRSVCAT (78 ± 4% of control). Thus, somatostatin may inhibit insulin gene transcription by insulin gene-specific effects as well as more general effects on gene expression. Both epinephrine and somatostatin inhibited expression of the human insulin-CAT reporter gene in a concentration-dependent manner that paralleled inhibition of insulin secretion. These studies indicate that epinephrine and somatostatin lower HIT cell insulin mRNA levels in part by inhibiting insulin gene transcription. Thus, hormonal inhibition of insulin secretion may be coupled with inhibition of insulin synthesis, thereby allowing the α-cell to match insulin supply to secretory demand.
Incidence of Renal Failure in NIDDM: The Oklahoma Indian Diabetes Study
Authors: Lee Elisa T , Lee Vivian S , Lu Min , Lee Jennifer S , Russell Dana , Yeh Jeunliang
Published: September 2013

The incidence of and risk factors for renal failure were determined in 912 Oklahoma Indians with non-insulin-dependent diabetes mellitus in a follow-up study conducted between 1987 and 1990. The incidence rate was 15.7/1,000 person-years after an average follow-up time of 10.2 years. Among those who had no qualitatively positive proteinuria at baseline, the incidence of renal failure was 10.3/1,000 person-years compared with 19.3 and 56.2/1,000 person-years, respectively, in those with slight and heavy proteinuria at baseline. Fasting plasma glucose (FPG) ≥ 11.1 mM (200 mg/dl) increased the risk of renal failure to 2.9-fold (95% confidence interval [CI] = 1.9–4.6) higher than a level < 7.8 mM (140 mg/dl), and twofold (95% CI = 1.4–3.1) higher than a level between 7.8 (140 mg/dl) and 11.1 mM (200 mg/dl). The hypertensive patient had twice the incidence of renal failure than the normotensive subject (rate ratio = 2.1, 95% CI = 1.4–3.0). Patients with a lower blood pressure under antihypertensive medication had a lower incidence of renal failure than those whose hypertension remained uncontrolled with or without use of medication. Significant independent risk factors for renal failure, identified from Cox's proportional hazards model, were duration of diabetes, FPG, age, hypertension, and insulin use (P < 0.05). In patients without proteinuria at baseline, FPG and hypertension were significant predictors of renal failure as identified by multivariate analyses, whereas in patients who had proteinuria at baseline, insulin use was significant. Thus, hyperglycemic and hypertension control are suggested strongly for diabetic Oklahoma Indians as potential strategies to prevent the development of renal failure.
Suppression of Pentosidine Formation in Galactosemic Rat Lens by an Inhibitor of Aldose Reductase
Authors: Nagaraj Ramanakoppa H , Prabhakaram Malladi , Ortwerth Beryl J , Monnier Vincent M
Published: September 2013

Recent work from our laboratory revealed a correlation between the degree of protein pigmentation in human cataractous lens and the advanced Maillard reaction as reflected by pentosidine formation. Although the data suggested a role for ascorbate in pentosidine formation in senile cataractous lenses, elevated pentosidine levels in diabetic cataracts suggested that glucosylation may be involved directly in pentosidine biosynthesis. To clarify this issue, we quantified pentosidine in lenses from rats with experimental galactosemia with and without aldose reductase inhibitor treatment. At 12 months, pentosidine-like fluorescence (335/385 nm) was three to six times higher (P < 0.0001) in water soluble and insoluble crystallins of galactosemic compared with nongalactosemic rats. Actual pentosidine levels increased shortly after onset of galactosemia. Contents in water-insoluble crystallins were 6.32 ± 2.2 and 1.40 ± 0.66 pmol/mg protein in galactosemic and control lenses, respectively (P < 0.001). Fluorescence and pentosidine were suppressed to almost control levels upon treatment with sorbinil. Incubation experiments showed that pentosidine could form slowly from galactose, but much more rapidly from ascorbate and its oxidation products. Its formation could be inhibited partly by both reduced and oxidized glutathione or ε-aminocaproic acid. The requirement of oxygen for pentosidine formation suggests that oxidative stress associated with glutathione depletion and ascorbate oxidation are plausible mechanisms for rapid pentosidine formation upon onset of galactosemia. In contrast, Maillard reaction by glycoxidation products may account for the sustained increase in pentosidine. Both these events may be linked to the newly recognized pseudohypoxic state of cells exposed to high sugar concentrations.
Human Islet Amyloid Polypeptide Accumulates at Similar Sites in Islets of Transgenic Mice and Humans
Authors: de Koning Eelco J P , Höppener Jo W M , Verbeek J Sjef , Oosterwijk Cor , van Hulst Karen L , Baker Catherine A , Lips Cees J M , Morris John F , Clark Anne
Published: September 2013

The cellular mechanisms responsible for conversion of islet amyloid polypeptide (IAPP) into insoluble amyloid deposits in non-insulin-dependent diabetes mellitus (NIDDM) are not clear. Overexpression of IAPP and the amino acid sequence of human IAPP (hIAPP) have both been implicated. To examine factors involved in amyloid formation, transgenic mice expressing the hIAPP or rat IAPP (rIAPP) gene were generated. These mice had elevated plasma IAPP concentrations, and they were normoglycemic and normoinsulinemic. No amyloid deposits were detected by light microscopy. To examine the ultrastructure of islets, pancreatic tissue was studied from hIAPP and rIAPP transgenic mice and from age-matched control mice by immunoelectron microscopy. IAPP was immunolocalized in β-cell secretory granules of all mice, and the COOH- and NH2-terminal flanking peptides of hIAPP were localized in β-cell granules of hIAPP mice. Accumulations of nonfibrillar perivascular IAPP-immunoreactive material were found between capillaries and β-cells in hIAPP transgenic mice but not in rIAPP transgenic or control mice. Similar nonfibrillar masses were identified in islets of an NIDDM patient. Secondary lysosomes in β-cells and macrophages of hIAPP transgenic mice showed dense labeling for IAPP. We suggest that hIAPP is degraded more slowly than rIAPP or mouse IAPP by β-cell lysosomes. Accumulations of IAPP in islet perivascular spaces may represent the early stages of islet amyloid formation.
Six Mutations in the Glucokinase Gene Identified in MODY by Using a Nonradioactive Sensitive Screening Technique
Authors: Hager Jörg , Blanché Hélène , Sun Fang , Vaxillaire Nathalie Vionnet Martine , Poller Wolfgang , Cohen Daniel , Czernichow Paul , Velho Gilberto , Robert Jean-Jacques , Cohen Nadine , Froguel Philippe
Published: September 2013

We have reported that 56% of French families with maturity-onset diabetes of the young (MODY) carry a mutation in the glucokinase gene (GCK). Therefore, we have established a quick and sensitive nonradioactive technique (with the PhastSystemTM based on single-strand conformation polymorphism [SSCP] analysis) to routinely screen the 12 exons of GCK for mutations. We have studied GCK in 12 young hyperglycemic patients with a strong family history of type II diabetes. SSCP variants were observed in 6 of those 12 patients (50%), which cosegregated with diabetes in five families where DNA from additional members was available. Direct sequencing identified a 10-bp (base pair) deletion in exon 3; a 33-bp deletion at the exon 5/intron 5 junction, including the two consensus bases (GT) of the donor splice site; a nonsense mutation in exon 5 (Arg186 → Stop) in a Black-African family, which has been identified previously in a Caucasian family; and three missense mutations: Thr209 → Met209 in exon 6, Gly261 → Glu261 in exon 7, and Arg36 → Trp36 in exon 2. The missense mut ation in exon 2 was found only in the second and third generation of the tested family but not in the first. To our knowledge, this is the first time that a de novo mutation of GCK is reported within a family. All six families carrying a mutation in GCK were typical MODY and most of their affected members had a mild form of diabetes. This nonradioactive SSCP technique may be useful to routinely diagnose glucokinase deficiency, which is an important cause of hyperglycemia among young type II diabetic patients.
Maternally inherited diabetes and deafness is a distinct subtype of diabetes and associates with a single point mutation in the mitochondrial tRNA Leu(UUR) gene
Authors: van den Ouweland Johannes M W , Lemkes Herman H P J , Trembath Richard C , Ross Richard , Velho Gilberto , Cohen Daniel , Froguel Philippe , Maassen J Antonie
Published: September 2013

We have recently reported an A to G transition at nucleotide position 3243 in the mitochondrial DNA (mtDNA) tRNALeu(UUR)) gene in a large family with non-insulin-dependent diabetes mellitus (NIDDM). Characteristic was its maternal transmission and an associated sensorineural hearing loss. In a screening of a Dutch and French NIDDM population for the presence of the tRNALeu(UUR)) mutation we identified two new pedigrees in which NIDDM is present in combination with deafness. The mode of inheritance agrees with a maternal one. This result shows that patients with a phenotype of NIDDM and deafness can be identified within groups of NIDDM patients based on the tRNALeu(UUR)) mutation. The same mutation has also been linked to the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). How the same mutation can give rise to different clinical phenotypes is not clear. We obtained the complete mtDNA sequence from our initial pedigree and identified a number of additional mutations that could confer the phenotype of the tRNA(Leu(UUR)) mutation to diabetes. We examined the presence of these additional, potentially pathogenic mutations in the mtDNA from the two new pedigrees and from a previously described British pedigree. The absence of these mutations in all three pedigrees shows that the tRNALeu(UUR)) mutation alone associates with the phenotype of NIDDM and deafness. We conclude that maternally inherited diabetes and deafness is a distinct subtype of diabetes that is associated with a single mitochondrial tRNALeu(UUR) mutation. We propose the abbreviation MIDD for this particular subtype.
Human Glucagon-Like Peptide-1 Receptor Gene in NIDDM: Identification and Use of Simple Sequence Repeat Polymorphisms in Genetic Analysis
Authors: Tanizawa Yukio , Riggs Andrew C , Elbein Steven C , Whelan Alison , Donis-Keller Helen , Permutt M Alan
Published: September 2013

Glucagon-like polypeptides, GLP-1-(7-36)-amide and GLP-1-(7-37), are important regulators of insulin synthesis and secretion by islet beta-cells. The hypothesis to be tested in this study was that defects in the islet beta-cell GLP-1 receptor gene contribute to the impaired glucose-regulated insulin secretion of non-insulin-dependent diabetes mellitus (NIDDM). Human islet GLP-1 receptor genomic clones were isolated, and two highly polymorphic simple sequence repeat regions (GLP-1R-CA1 and GLP-1R-CA3) were identified. Polymerase chain reaction assays were developed to define alleles. For GLP-1R-CA1, 14 alleles were observed in African-Americans (heterozygosity [het] = 0.78) and 6 alleles in Caucasians (het = 0.67). For GLP-1R-CA3, 16 alleles were observed in African Americans (het = 0.89) and 8 alleles in Caucasians (het = 0.83). By genotyping all members of the 40 reference Centre d'Etude du Polymorphisme Humain pedigrees at GLP-1R-CA3, the human GLP-1 receptor gene was uniquely placed on chromosome 6p between GLO1 and D6S19, 20.4 cM from human leukocyte antigen. To assess the possible role of the GLP-1 receptor gene in determining the genetic susceptibility to NIDDM, allelic frequencies of GLP-1R-CA1 and GLP-1R-CA3 were compared between African-American NIDDM patients (n = 95) and control subjects (n = 93). The frequencies did not differ between the two groups at either GLP-1R-CA1 or GLP-1R-CA3. The GLP-1 receptor gene simple-sequence repeat polymorphisms were used for linkage analysis in Utah Mormon pedigrees (n = 16) with NIDDM. Linkage could be rejected (logarithm of odds scores <–2.0) under both dominant and recessive models to distances in excess of 5 cM. Thus, we concluded that inherited defects in the GLP-1 receptor are not a major risk factor for NIDDM in these two racial groups.
Intracerebroventricular Administration of Neuropeptide Y to Normal Rats Has Divergent Effects on Glucose Utilization by Adipose Tissue and Skeletal Muscle
Authors: Zarjevski Nicolas , Cusin Isabelle , Vettor Roberto , Rohner-Jeanrenaud Françise , Jeanrenaud Bernard
Published: September 2013

Given that several genetically obese rodents characterized by hyperphagia, hyperinsulinemia, and insulin resistance have increased hypothalamic neuropeptide Y (NPY) mRNA and peptide content, the impact of NPY administered intracerebroventricularly (i.c.v.) for 7 days to normal, awake rats was investigated. NPY produced marked hyperphagia, increased body weight gain, increased basal insulinemia, and, more importantly, a much greater insulin response to meal feeding than that of saline-infused controls. NPY administration also resulted in a pronounced increase in the in vivo insulin-stimulated glucose uptake by adipose tissue but in a marked decrease in uptake by eight different muscle types. Increased insulin responsiveness of the glucose transport process by adipose tissue was accompanied by increases in both GLUT4 mRNA and protein levels. In contrast, the decreased insulin responsiveness of glucose uptake in muscles from NPY-administered rats was not related to GLUT4 expression. We conclude that i.c.v. NPY administration to normal rats produces a hormonal-metabolic situation that is similar to that reported in the dynamic phase of the genetic obesity of the fa/fa strain. Thus, NPY could be of primary importance in the establishment of obesity syndromes with incipient insulin resistance.
Hypoglycemia-Induced Autonomic Failure in IDDM is Specific for Stimulus of Hypoglycemia and Is Not Attributable to Prior Autonomic Activation
Authors: Rattarasarn Chatchalit , Dagogo-Jack Samuel , Zachwieja Jeffery J , Cryer Philip E
Published: September 2013

We hypothesized, first, that recent antecedent hypoglycemia causes reduced autonomic responses to subsequent hypoglycemia in patients with well-controlled insulin-dependent diabetes mellitus (IDDM) and that the reduced responses are specific for the stimulus of hypoglycemia while the responses to other stimuli are unaltered and, second, that reduced autonomic responses, specifically sympathochromaffin, so-induced are not simply the result of prior activation of the system. To test the first hypothesis, eight patients with IDDM, selected for HbA1c levels < 8.0% and the absence of classic diabetic autonomic neuropathy, were studied twice. On one occasion, clamped hypoglycemia (∼ 2.8 mM) was produced at 1400–1600 on days 2 and 3; on the other occasion clamped euglycemia (∼ 5.6 mM) was produced at those times. On both occasions, autonomic responses to hypoglycemia (∼ 2.8 mM) were determined the morning of day 3 and those to standing, exercise, and a formula meal the morning of day 4. Following afternoon hypoglycemia, 1) the adrenomedullary epinephrine (EPI) response to hypoglycemia was reduced (P = 0.0397) but that to standing, exercise, and a meal were unaltered; 2) the sympathetic neural norepinephrine (NE) response to standing and to exercise was unaltered; and 3) the partially parasympathetic neural-mediated pancreatic polypeptide response to a meal was unaltered. To test the second hypothesis, seven nondiabetic subjects were studied twice, once with cycle exercise (60% peak VO2 × 60 min) and once without exercise 90 min before clamped hypoglycemia (∼ 2.8 mM). Prior exercise had no effect on the EPI, NE, or pancreatic polypeptide responses to hypoglycemia. We conclude, first, that the phenomenon of hypoglycemia-associated autonomic failure can be induced in patients with well-controlled IDDM and is specific for the stimulus of hypoglycemia and, second, that this is not simply the result of prior activation of the system.
Pulsatile Insulin Secretion from Isolated Human Pancreatic Islets
Authors: Marchetti Piero , Scharp David W , Mclear Melissa , Gingerich Ronald , Finke Edward , Olack Barbara , Swanson Carol , Giannarelli Rosa , Navalesi Renzo , Lacy Paul E
Published: September 2013

Insulin secretion from the pancreas is pulsatile. The precise site and function of the pacemaker that regulates insulin periodicity in humans have not been determined. We isolated human pancreatic islets from five cadaver organ donors by collagenase digestion and density gradient purification. After 24 h of culture in CMRL-1066 medium at 37°C, aliquots of 200 islets were perifused (1 ml/min for 120 min) with glucose and other secretagogues in oxygenated Krebs-Ringer bicarbonate solution at 37°C. Samples for insulin measurement were taken every minute, and insulin secretion was analyzed by the Clifton and Steiner cycle detection technique. With 3.3 mM glucose (n = 17), insulin oscillations were demonstrated with a periodicity of 9.8 ± 0.1 min (means ± SE), mean amplitude was 16.8 ± 1.8 pM, and overall mean insulin release was 43.8 ± 4.2 pM. With 16.7 mM glucose (n = 14), no change of insulin periodicity was observed (10.2 ± 0.9 min), mean amplitude was 41.4 ± 10.2 pM (P < 0.01 vs. 3.3 mM glucose), and mean insulin release was 118.2 ± 19.2 pM (P < 0.01 vs. 3.3 mM glucose). Both at 3.3 and 16.7 mM glucose, the addition of 1.4 mM glucagon (n = 4), 15 mM arginine (n = 4), or 100 µg/ml tolbutamide (n = 4) caused no change of insulin periodicity but enhanced mean amplitude and mean insulin release compared with glucose alone. These results show that a pacemaker is located within the islets that regulates pulsatile insulin secretion in humans; the pacemaker is remarkably stable, because its periodicity is not affected by factors altering insulin secretion.
Early Environmental Events as a Cause of IDDM: Evidence and Implications
Authors: Leslie R David , Elliott Robert B
Published: September 2013

Insulin-dependent diabetes mellitus (IDDM) is caused by destruction of the insulin-secreting β-cells of the islets of Langerhans. It is proposed that the disease is caused by nongenetic, probably environmental, factors operating in a genetically susceptible host to initiate a destructive immune process. These environmental factors may operate over a limited period in early childhood to induce the immune process that destroys the islet β-cell. Thereafter, there is a long prodrome before the onset of clinical diabetes, during which clinical, immune, and metabolic changes can be detected. If these proposals are correct, epidemiological studies should focus on environmental events in early childhood that might induce, or accelerate, the disease process. Moreover, it should be possible to identify, from an early age, changes in the prediabetic period that persist to diagnosis and have predictive value. The variable age of presentation of IDDM may, therefore, reflect different rates of disease progression rather than different ages of exposure to the critical environmental events. Those patients in whom the disease process is slow could present with IDDM as adults, develop diabetes that does not require insulin treatment, or even fail to develop diabetes altogether. These proposed features, if confirmed, would have important implications for the prediction of IDDM and raise the possibility that modulation of the destructive immune process could prevent progression to clinical diabetes.
Lack of Immunohistological Changes in the Islets of Nondiabetic, Autoimmune, Polyendocrine Patients With β-Selective GAD-Specific Islet Cell Antibodies
Authors: Wagner Richard , McNally Jassica M , Bonifacio Ezio , Genovese Stefano , Foulis Alan , McGill Margaret , Christie Michael R , Betterle Corrado , Bosi Emanuele , Bottazzo Gian Franco
Published: September 2013

We examined the pancreases from three nondiabetic, autoimmune, polyendocrine patients with islet cell antibodies (ICAs) and glutamic acid decarboxylase (GAD) antibodies who died without developing insulin-dependent diabetes mellitus (IDDM). All three patients had the β-selective GAD-specific ICA subtype and antibodies to the GAD-derived 50 kD tryptic fragment. None had whole islet ICA or antibodies to the non-GAD-derived 37k islet antigen, which appear to be more closely associated with IDDM than antibodies to GAD. The three patients also were negative for insulin autoantibodies. Islets within pancreas from patients 1 and 2 appeared well preserved as assessed by hematoxylin and eosin staining. In these two patients, insulin content, as assessed by indirect immunofluorescence on cryostat sections, was normal. Patient 3 had a prolonged postmortem time, and the islet insulin content was reduced slightly. In all three pancreases, no evidence was found of increased human leukocyte antigen class I or de novo class II molecule expression on islet cells, and islet infiltration by T- or B-cells or macrophages was not detected. Islet capillary endothelial cells did not show signs of hypertrophy. No immunoglobulin or complement deposition within or around islets was found. These data indicate that humoral GAD autoimmunity does not necessarily associate with visible β-cell damage.
Non-Insulin-Mediated Glucose Disappearance in Subjects With IDDM: Discordance Between Experimental Results and Minimal Model Analysis
Authors: Quon Michael J , Cochran Craig , Taylor Simenon I , Eastman Richard C
Published: September 2013

Both insulin and glucose contribute to the regulation of glucose metabolism in vivo. We directly measured the ability of glucose per se to promote glucose disposal in subjects with insulin-dependent diabetes mellitus (IDDM). We compared our results with predictions of the minimal model of glucose metabolism. To identify minimal model parameters, a frequently sampled intravenous glucose tolerance test (FSIVGTT) was administered to each subject while they were connected to a Biostator (a device that monitors blood glucose and gives insulin to mimic normal insulin secretion). Data from this test reflected normal glucose tolerance and were in excellent agreement with minimal model predictions. The FSIVGTT was then repeated without the Biostator in the same diabetic subjects in order to directly measure the effect of glucose per se to promote glucose disposal in the absence of an incremental insulin effect (a basal insulin drip was maintained). To compare these results with minimal model predictions, the equations describing glucose disappearance in the absence of an incremental insulin effect were solved using parameters identified from the Biostator experiment. The glucose disappearance measured in the absence of an incremental insulin response was much slower than the minimal model predictions. Thus, the minimal model appears to overestimate the effect of glucose per se on glucose uptake and underestimate the contribution of incremental insulin.
Clinical and Histological Correlations of Decline in Renal Function in Diabetic Patients With Proteinuria
Authors: Taft Jonathan L , Nolan Christoper J , Yeung Stella P , Hewitson Timothy D , Martin F Ian
Published: September 2013

In 47 patients with diabetic nephropathy (29 type I, 18 type II) renal function and blood pressure (BP) (treated with or without an angiotensin-converting enzyme [ACE] inhibitor, enalapril [10 mg], in 38 hypertensive patients) were followed over 4 years. A percutaneous renal biopsy was performed in all patients initially and repeated in a representative 19 patients with treated hypertension after 4 years. Mean glomerular volume (MGV), interstitial fibrosis (IF), capillary volume, and sclerosed glomeruli (GS) were measured histomorphometrically. Mean fall in creatinine clearance (CCr) was 11.8% after 4 years with no difference between treatment groups or type of diabetes. BP both initially and during treatment correlated with initial and final serum creatinine and CCr (P < 0.01). There were no histomorphometric differences between type I and type II patients or hypertension treatment groups. Initial IF correlated with initial and final serum creatinine and CCr (P < 0.05) in all patients and type I patients alone, MGV correlated inversely with CCr in type I patients (P < 0.05). After 4 years, IF (24.8 vs. 30.0%, P < 0.01) and GS (26 vs. 37%, P < 0.05) increased significantly, and increase in IF correlated with fall in CCr (P < 0.01). Proteinuria and HbA1 did not correlate with indexes of function or structure. In this longitudinal study of patients with diabetic nephropathy, there was a close relation between BP and renal function but no difference between treatment with enalapril and other hypertensive agents. The correlations between renal function and histology at entry and after 4 years suggest that IF is a co-determinant of renal function in diabetic nephropathy.
Description of a Second Microsatellite Marker and Linkage Analysis of the Muscle Glycogen Synthase Locus in Familial NIDDM
Authors: Elbein Steven C , Hoffman Michae , Ridinger David , Otterud Brith , Leppert Mark
Published: September 2013

Non-insulin-dependent diabetes mellitus (NIDDM) is characterized by impaired insulin-stimulated glucose uptake into glycogen. Both biochemical and genetic data have implicated glycogen synthase as a candidate for the genetic predisposition to diabetes. To test this hypothesis, we isolated cosmid clones containing genomic DNA for the glycogen synthase (GSY) gene and identified a region of 20 GT repeat units in a clone that extended 15 kilobases 3′ to the gene. This region was highly polymorphic with nine alleles (heterozygosity 0.74). With the use of this polymorphism, the GSY was mapped on chromosome 19q between markers D19S217 and D19S210 and at Θ = 0.036 from the histidine-rich calcium-binding protein (HRC) locus. Linkage to GSY was rejected under multiple models with logarithm of odds (LOD) scores of −1.36 to −5.22. In contrast, we could not reject linkage under dominant and intermediate (additive) models for the HRC locus (maximum LOD scores 1.51 and 1.54), despite the close proximity to GSY. Multipoint analysis of NIDDM versus GSY and HRC placed the putative diabetes locus centromeric to HRC and away from GSY. Furthermore, analysis of the previously associated Xba I polymorphism suggested neither linkage nor sib-pair sharing. We conclude that mutations of the GSY gene are unlikely to play a major role in the predisposition to NIDDM in our families. However, we cannot exclude a modifying role in a polygenic disorder or an important role in some families. The moderately positive LOD scores near the HRC locus suggest a need for evaluation of this region in additional NIDDM families.
Insulin Action, Diabetogenes, and the Cause of Type II Diabetes
Authors: Kahn C. Ronald
Published: September 2013

The person who passes urine which is exceedingly sweet, cool, slightly viscid, turbid, and resembling the juices of the sugarcane … suffers from glycosuria. … There are two types of urinary disorders—one, natural due to genetic factors, and the other due to indiscreet living or dietetic indiscretions. The patient suffering from the former is thin, pale, eats less and drinks too much.… The patient with the latter is usually obese, eats a lot, is stout, of sedentary habits and sleeps too much.
NIDDM and Its Metabolic Control Predict Coronary Heart Disease in Elderly Subjects
Authors: Kuusisto Johanna , Mykkänen Leena , Pyörälä Kalevi , Laakso Markku
Published: September 2013

The aim of this study was to evaluate whether noninsulin-dependent diabetes (NIDDM) and its metabolic control and duration predict coronary heart disease (CHD) events during a 3.5-year follow-up in a randomly selected Finnish population sample 65–74 years of age at baseline. Of 1,298 subjects participating in the baseline study, 1,069 were nondiabetic and 229 had NIDDM. During the follow-up, 3.4% of nondiabetic and 14.8% of NIDDM subjects died from CHD or had a nonfatal myocardial infarction (MI). The impact of NIDDM on CHD mortality and morbidity was more marked in women than in men. Odds ratios (ORs) and their 95% confidence intervals for CHD death and nonfatal MI in women with NIDDM compared with women with normal glucose tolerance were 11.7 (3.8–36.4) and 4.7 (3.6–6.1). In men, the corresponding ORs were 0.43 (0.1–1.9) and 1.4 (0.6–3.2). In multiple logistic regression analyses including all study subjects, NIDDM (P < 0.01), male sex (P < 0.05), and previous MI (P < 0.01) predicted CHD death (n = 45). NIDDM (P < 0.01), male sex (P < 0.05), previous MI (P < 0.05), current smoking (P < 0.001), systolic blood pressure (P < 0.001), and low high-density lipoprotein cholesterol (P < 0.01) predicted all CHD events (CHD death or nonfatal MI) (n = 107). In NIDDM subjects, only glycated hemoglobin A1c (GHbsA1c) at baseline (P < 0.01) and duration of diabetes (P < 0.05) predicted CHD death (n = 15) and all CHD events (n = 33). There was a significant increase in the risk of CHD death and all CHD events in NIDDM subjects with GHbA1c levels higher than 7.0% compared with diabetic subjects with lower GHbA1c (ORs 4.3 [1.1–16.7] and 2.2 [1.0–5.1]). In conclusion, NIDDM and its metabolic control and the duration of diabetes are important predictors of CHD in elderly subjects, particularly in women.
Differentiating Glucose Toxicity From Glucose Desensitization: A New Message From the Insulin Gene
Authors: Robertson R Paul , Olson L Karl , Zhang Hui-Jian
Published: September 2013

Our perspective is that the concepts of glucose toxicity and glucose desensitization should be differentiated because they carry very different connotations. The term glucose desensitization most properly refers to a pharmacological event involving a temporary, readily induced, physiological and reversible state of cellular refractoriness because of repeated or prolonged exposure to high concentrations of glucose. The term glucose toxicity should be reserved for nonphysiological, irreversible alterations in cellular function caused by chronic exposure to high glucose concentrations. With regard to the pancreatic islet β-cell, the mechanism of action for glucose desensitization seems most likely to be expressed at the level of the insulin exocytotic apparatus or insulin stores within the β-cell, whereas the mechanism of action for glucose toxicity may be at the level of insulin gene transcription. This differentiation raises the possibility that exposure of patients to chronic hyperglycemia may cause glucose toxic effects on the process of insulin gene transcription and/or expression that are irreversible. If so, this may contribute to so-called secondary drug failure and, in any event, reemphasizes the need to intensify therapeutic efforts to better regulate glycemia in type II diabetes.
Function, Mass, and Replication of Porcine and Rat Islets Transplanted into Diabetic Nude Mice
Authors: Davalli Alberto M , Ogawa Yoshiji , Scaglia Luisa , Wu Ying-Jian , Hollister Jennifer , Bonner-Weir Susan , Weir Gordon C
Published: September 2013

Well-characterized aliquots of adult porcine and rat islets of comparable β-cell mass were transplanted under the kidney capsule of streptozotocin-induced diabetic nude mice. In both porcine and rat islet grafts, β-cell mass decreased significantly in the first 2 months and stabilized thereafter. As with β-cell mass, insulin content decreased significantly in the first 2 months to almost 40% of that originally implanted. In porcine grafts, however, insulin content at 4 months was significantly higher than at 2 months. The endocrine non-β-cell mass of grafts also decreased significantly after transplantation: in porcine grafts, the decrease was less than in rat and was limited to the first 2 months. β-cell replication of engrafted islets was significantly lower in porcine than in rat grafts. Although β-cell mass of porcine and rat grafts was similar at all time periods, recipients of porcine islets required a significantly longer time to reach normal glucose levels; nonetheless, their blood glucose levels continued to decrease and stabilized at levels significantly lower than those of normal mice. During oral and intraperitoneal glucose tolerance tests, blood glucose increased only slightly in both the recipients of porcine and rat grafts. When graft-bearing kidneys were perfused in situ, porcine islet grafts showed a 20-fold increase in insulin release in response to both glucose and arginine. In conclusion, this evidence that adult porcine islet grafts can bring glucose levels to those that are normal for humans provides further support of their potential for human islet replacement therapy.
Hyperglycemia and Diabetic Kidney Disease: The Case for Transforming Growth Factor–β as a Key Mediator
Authors: Sharma Kumar , Ziyadeh Fuad N
Published: September 2013

Renal cells are a rich source of transforming growth factor (TGF)-β, and they serve as targets for its actions. Our hypothesis that activation of the TGF-β system in the kidney is implicated in the development of diabetic renal disease stems from the close similarity of actions of TGF-β and high ambient glucose on renal cell growth and extracellular matrix metabolism. Proximal tubule cells and glomerular mesangial cells cultured in high glucose concentration express increased TGF-β1 mRNA and protein levels, and treatment with anti-TGF-β antibodies results in prevention of the effects of high glucose to induce cellular hypertrophy and stimulate collagen biosynthesis. Several in vivo studies by different groups of investigators have reported overexpression of TGF-β in the glomeruli in human and experimental diabetes. We have also observed that the development of renal hypertrophy in the insulin-dependent diabetic BB rat and NOD mouse is associated with increased expression of TGF-β1 in the kidney and that short-term administration of antibodies capable of neutralizing the activity of TGF-β in the streptozotocin mouse model of diabetes results in attenuation of whole kidney and glomerular hypertrophy and overexpression of mRNAs encoding matrix components. Together, these findings are consistent with the hypothesis that the diabetic state stimulates TGF-β expression in the kidney and that in turn this growth factor may mediate, in an autocrine/paracrine manner, some of the principal early manifestations of diabetic renal disease. Demonstrating a causal link between upregulation of glomerular TGF-β and the subsequent development of diabetic glomerulosclerosis will require long-term interventional studies designed to intercept the TGF-β system in the kidney.