bluuebunny/crossref_metadata_2025 huggingface dataset:
Islet Transplantation in Spontaneously Diabetic BB/Wor Rats
Authors: Hegre Orion D , Enriquez Albert J , Ketchum Robert J , Weinhaus Anthony J , Serie Janet R
Published: September 2013

We investigated the effectiveness of islet transplantation as therapy in an animal model of spontaneous type I (insulin-dependent) diabetes mellitus. Grafting MHC-matched and -mismatched islets with the spontaneously diabetic BB rat as a model has been previously reported to result in recurrence of the disease in the grafted tissue. When transplanted with nonimmunogenic islets isolated by nonenzymatic culture, we found that MHC-matched grafts proved to be susceptible to disease recurrence when allowed to remain in situ until ketosis developed in the host. Conversely, the MHC-mismatched grafts did not succumb to the disease process despite the destruction of the β-cell population of the endogenous pancreas. Four manifestly hyperglycemie BB/Wor rats received sufficient islet mass by allotransplantation to reverse this state. All four animals had ameliorated conditions, and three of the four were restored to a normoglycemic state. Recurrence of diabetes in the BB rat was not observed.
Resistance to Insulin-Stimulated Glucose Uptake in Adipocytes Isolated From Spontaneously Hypertensive Rats
Authors: Reaven Gerald M , Chang Helen , Hoffman Brian B , Azhar Salman
Published: September 2013

The ability of insulin to stimulate glucose uptake and inhibit catecholamine-induced lipolysis was measured in adipocytes of similar size isolated from SHR and WKY rats. The results indicate that glucose transport was decreased in adipocytes from SHR rats; both basal (19 ± 2 vs. 32 ± 2 fmol · cell−1 · s−1 P < .001) and maximal (207 ± 30 vs. 373 ± 20 fmol · cell−1 · s−1 P < .01) insulin-stimulated glucose transport were lower in SHR than in WKY rats. In addition, the EC50 of insulin-stimulated glucose uptake was higher (921 ± 82 vs. 557 ± 69 pM insulin, P < .05) in adipocytes from SHR rats than from WKY rats. The ability of phenylisopropyladenosine (PIA) to modulate basal and maximal insulin-stimulated glucose uptake was compared in adipocytes from SHR and WKY rats. These results also demonstrated that glucose uptake was decreased in adipocytes from SHR rats and that PIA similarly enhanced both basal and maximal insulin-stimulated glucose uptake in adipocytes from both groups. Although maximal isoproterenol-stimulated lipolysis was decreased in adipocytes from SHR rats, the ability of insulin to inhibit catecholamine-stimulated lipolysis was at least as great in adipocytes from SHR as from WKY rats. Despite the decrease in insulin-stimulated glucose transport in isolated adipocytes from SHR rats, total number of insulin receptors, their affinity for insulin, and the ability of insulin to stimulate receptor-associated tyrosine kinase activity were similar in adipocytes from SHR and WKY rats. These results demonstrate a defect in both basal and insulin-stimulated glucose uptake and a loss of sensitivity of the adipocyte glucose-transport system to insulin in adipocytes from SHR rats and suggest that the site of the abnormality is distal to the insulin receptor.
Antidepressant Effects of Tricyclic Antidepressants and Selective Serotonin-Uptake Blockers in Diabetic Rats
Authors: Massol Jacques , Martin Patrick , Puech Alain Jacques
Published: September 2013

Because it was reported that diabetic rodents were resistant to the effects of several tricyclic antidepressants in various psychopharmacological models, we decided to test the hypothesis that the serotonergic dysfunction seen in diabetes might participate in this phenomenon. The ability of three serotonin-uptake blockers to reverse the performance deficit in learning induced by previous uncontrollable stress (learned-helplessness paradigm) was investigated in streptozocin-induced diabetic rats. Three weeks after induction of diabetes, rats were subjected to a session of 60 inescapable electric foot shocks and, after 48 h, to three daily sessions of two-way shuttle-box training. Three serotonin-uptake blockers were given intraperitoneally over 5 consecutive days. As with nondiabetic rats, citalopram (1 mg · kg−1 · day−1), fluoxetine (2 and 4 mg · kg−1 · day−1), and fluvoxamine (4 mg · kg 1 · day−1) reduced the number of escape failures in diabetic rats. From these data, we suggest that it is unlikely that the impaired response of diabetic rats to tricyclic antidepressants is caused by serotonergic dysfunction.
Profound Peripheral Insulin Resistance, Independent of Obesity, in Polycystic Ovary Syndrome
Authors: Dunaif Andrea , Segal Karen R , Futterweit Walter , Dobrjansky Areta
Published: September 2013

Hyperinsulinemia secondary to a poorly characterized disorder of insulin action is a feature of the polycystic ovary syndrome (PCO). However, controversy exists as to whether insulin resistance results from PCO or the obesity that is frequently associated with it. Thus, we determined in vivo insulin action on peripheral glucose utilization (M) and hepatic glucose production (HGP) with the euglycemic glucose-clamp technique in obese (n = 19) and nonobese (n = 10) PCO women and age- and body-composition-matched normal ovulatory women (n = 11 obese and n = 8 nonobese women). None had fasting hyperglycemia. Two obese PCO women had diabetes mellitus, established with an oral glucose tolerance test; no other women had impairment of glucose tolerance. However, the obese PCO women had significantly increased fasting and 2-h glucose levels after an oral glucose load and increased basal HGP compared with their body-composition-matched control group. There were statistically significant interactions between obesity and PCO in fasting glucose levels and basal HGP (P < .05). Steady-state insulin levels of ∼100 μU/ml were achieved during the clamp. Insulin-stimulated glucose utilization was significantly decreased in both PCO groups whether expressed per kilogram total weight (P < .001) or per kilogram fat free mass (P < .001) or when divided by the steady-state plasma insulin (I) level (M/I, P < .001). There was residual HGP in 4 of 15 obese PCO, 0 of 11 obese normal, 2 of 10 nonobese PCO, and 0 of 8 nonobese normal women. The metabolic clearance rate of insulin did not differ in the four groups. We conclude that 1) PCO women have significant insulin resistance that is independent of obesity, changes in body composition, and impairment of glucose tolerance, 2) PCO and obesity have a synergistic deleterious effect on glucose tolerance, 3) hyperinsulinemia in PCO is not the result of decreased insulin clearance, and 4) PCO is associated with a unique disorder of insulin action.
Cardiac Metabolic and Hemodynamic Effects of Insulin in Patients With Coronary Artery Disease
Authors: Thomassen Anne , Nielsen Torsten T , Bagger Jens P , Henningsen Per
Published: September 2013

To assess the effects of insulin in stable coronary artery disease (CAD), 2 U i.v. insulin was given to 9 control and 10 CAD patients during coronary sinus catheterization. Hemodynamic and metabolic data were obtained before and for 90 min after insulin injection. Insulin induced no changes in heart rate, mean aortic pressure, rate-pressure product, coronary sinus flow, or coronary resistance. Metabolic changes were similar in both groups and included 1) 30% decrease of arterial glucose (P < .001) and 3-fold increase of myocardial glucose uptake (P < .001), 2) 1.5- to 2.5-fold elevation of arterial lactate (P < .001) and myocardial lactate usage (P < .001), respectively, 3) 50–70% suppression of arterial levels (P < .001) and myocardial uptake of free fatty acids (P < .01), and 4) 10% reduction of myocardial net oxygen consumption (P < .05). Myocardial citrate efflux increased in the CAD patients (P < .05), whereas alanine release rose only in control patients (P < .01), suggesting that glucose enters glycogen production in the CAD patients and pyruvate production in the control patients to a high degree. Myocardial glutamate uptake remained unchanged. In conclusion, insulin sensitivity was not altered in CAD. The insulin-induced shift from myocardial free fatty acid to carbohydrate usage may be beneficial to the ischemie heart by increasing glycogen stores, saving oxygen, and inhibiting an excess free-fatty acid concentration, which may be toxic during ischemia.
Hypoglycemia in IDDM
Authors: Cryer Philip E , Binder Christian , Bolli Geremia B , Cherrington Alan D , Gale Edwin A M , Gerich John E , Sherwin Robert S
Published: September 2013

Hypoglycemia causes substantial morbidity and some mortality in insulin-dependent diabetes mellitus (IDDM). It is often the limiting factor in attempts to achieve euglycemia. The prevention or correction of hypoglycemia normally involves both dissipation of insulin and activation of glucose counterregulatory systems. Among the latter, glucagon plays a primary role initially, whereas epinephrine is not critical, although it becomes critical when glucagon is deficient. Growth hormone and cortisol play demonstrable roles in recovery from prolonged hypoglycemia. Glucose autoregulation may be involved in defense against severe hypoglycemia. With respect to pathophysiology, counterregulatory systems are involved in at least five clinical glucoregulatory syndromes. Defective glucose counterregulation is associated with, and best attributed to, combined deficiencies of the glucagon and epinephrine responses to plasma glucose decrements. Almost assuredly in concert with hypoglycemia unawareness, it results in a markedly increased frequency of severe hypoglycemia, at least during intensive therapy of IDDM. Defined as a night to morning increase in plasma glucose concentration, the dawn phenomenon is thought to result from dissipation of insulin plus the effects of nocturnal growth hormone secretion. Despite a sound rationale, the clinical relevance of the Somogyi phenomenon has been recently questioned. The clinical impression of altered glycemie thresholds for symptoms, i.e., patients with poorly controlled IDDM suffer symptoms of hypoglycemia at relatively high plasma glucose levels, whereas those with very well-controlled IDDM often tolerate subnormal glucose levels, has received experimental support. Clearly, hypoglycemia in IDDM is a problem that needs to be solved. Numerous issues need to be addressed through both basic and clinical research. Fundamentally, pending the prevention or cure of IDDM, we must learn to deliver insulin in a much more physiological fashion or to prevent, correct, or compensate for compromised glucose counterregulation if we are to achieve euglycemia safely in most patients with IDDM.
A Unified Hypothesis for the Complex Genetics of HLA Associations With IDDM
Authors: Nepom Gerald T
Published: September 2013

Our understanding of the role of HLA genes associated with insulin-dependentdiabetes mellitus (IDDM) is in disarray, despite recent improvements in the definition ofspecific alleles and haplotypes. Some genes are highly associated with IDDM, other genes are associated with resistance to IDDM, and some highly associated susceptibility genes are markedly influenced by trans-associated synergistic effects (DR3/4 heterozygotes) or protective effects (DR2/4 heterozygotes). This plethora of genetic associations has spawned the notion that there are many contributing susceptibility genes, which, in turn, has led to the search for shared structural features among different genes on IDDM-associated haplotypes. From a more mechanistic point of view, however, the wide range of variable IDDM associations, with both cis- and trans-encoded protective and/or synergistic effects, suggests a different approach. This article proposes a hypothesis in which the different HLA associations with IDDM can be simply explained by a single unifying concept: a hierarchy of affinities determines the interaction between a diabetogenic peptide and different class II molecules, and an individual is susceptible to IDDM if the class II molecule in that individual with the highest affinity for such a peptide is a DQβ susceptibility gene. The explicit formulation of this proposal and its genetic implications provide an explanation for HLA-encoded dominant “protection” and for some of the more subtle genetic observations related to cis and trans influences in IDDM susceptibility.
Increased Preproinsulin mRNA in Pancreatic Islets Incubated With Islet Cell–Stimulating Antibodies From Serums of Type I Diabetic Patients
Authors: Foggensteiner Lukas , Bone Adrian J , Webster Katherine A , Wilkin Terence J
Published: September 2013

We recently described autoantibodies that stimulate the release of insulin from pancreatic β-cells both in vitro and in vivo. The aim of this study was to establish whether islet cell–stimulating antibodies (ICSTAs) also increase islet cell preproinsulin mRNA content. Wistar rat islets, isolated by collagenase digestion, were exposed to 2.7 and 11.1 mM glucose. Insulin release increased 10-fold in response to the higher glucose concentration, and dot-blot analysis of islet mRNA with a rat preproinsulin cDNA probe showed a concomitant increase in mRNA levels. The globulin fractions of four test serums, three from patients with type I (insulin-dependent) diabetes and one from a patient with the insulin autoimmune syndrome, showed clear (5- to 8-fold) stimulation of insulin release. The nonglobulin fractions of these serums and both fractions of three control serums failed to stimulate secretion of insulin. The insulin mRNA content of islets incubated with the ICSTA globulin fractions was greatly increased compared with levels observed in islets treated with control serum globulin fractions. We conclude that ICSTAs not only can stimulate the release of insulin but also increase the preproinsulin mRNA content of islet cells.
Heart-Rate Variability and Cardiac Autonomic Function in Diabetes
Authors: Malpas Simon C , Maling Timothy J B
Published: September 2013

Cardiac autonomic function was measured in 25 subjects with insulin-dependent diabetes mellitus and 11 control subjects. Autonomic integrity was assessed with standard tests of autonomic function and a new technique of measuring heart-rate variability (HRV) for 24 h. All of the diabetic subjects were selected on the basis of peripheral or autonomic neuropathy or longterm poorly controlled diabetes. They were divided into groups according to presence or absence of vagal neuropathy based on the results of standard tests of autonomic function. Thirteen diabetic subjects had normal autonomic function tests (group 1), and vagal neuropathy was detected in 12 diabetic subjects (group 2). All subjects were monitored by ambulatory electrocardiograph, and the recordings were played back through an analyzer that identified and timed successive pulse (R-R) intervals. HRV was measured from the standard deviation of the successive differences between R-R intervals. HRV was significantly reduced in group 1 (mean ± SE 73 ± 9 ms) and group 2 (65 ± 12 ms) diabetic subjects compared with the control group (138 ± 10 ms). The standard tests of autonomic function did not distinguish the vagal dysfunction noted with HRV monitoring in group 1 diabetic subjects compared with control subjects. Measurement of 24-h HRV can detect small changes in cardiac autonomic function compared with currently available tests.
Glomerular Filtration Rate in Streptozocin-Induced Diabetic Rats: Role of Exchangeable Sodium, Vasoactive Hormones, and Insulin Therapy
Authors: Allen Terri J , Cooper Mark E , O'Brien Richard C , Bach Leon A , Jackson Bruce , Jerums George
Published: September 2013

The interrelationships of sodium and volume status, atrial natriuretic peptide (ANP), plasma renin activity (PRA), insulinlike growth factor I (IGF-I), and kidney weight and their influence on glomerular filtration rate (GFR) were investigated in rats during the first 4 wk of streptozocin-induced diabetes (STZ-D). In each of three experiments, untreated diabetic rats were compared with nondiabetic control rats and rats with varying degrees of glycemic control during insulin therapy. The first experiment evaluated exchangeable sodium, plasma volume, and GFR. In untreated diabetic rats, exchangeable sodium and plasma volume, but not GFR, were increased by ∼25% compared with control rats. Insulin-treated diabetic rats with plasma glucose levels ranging from 12 to 30 mM had increased GFR, whereas exchangeable sodium and plasma volume were reduced toward control values. Daily insulin therapy, titrated to maintain euglycemia, further reduced exchangeable sodium and plasma volume and decreased but did not normalize GFR. The second experiment evaluated the relationship between vasoactive hormones and GFR. In untreated diabetic rats, plasma ANP levels increased 89% and urinary cyclic GMP (cGMP) excretion increased 94%, with an 85% decrease in PRA, whereas GFR was unchanged. Moderate hyperglycemia (plasma glucose 12–30 mM) was associated with normalized plasma ANP levels and urinary cGMP excretion, a 52% decrease in PRA, and a 13% increase in GFR. The third experiment studied serial changes in food and water intake and vasoactive hormones and end-point measurement of kidney weight, GFR, and plasma IGF-I. In the untreated diabetic group, urinary cGMP excretion was significantly elevated after 3 wk, whereas the reduction in PRA levels was apparent after 1 wk. Plasma IGF-I decreased 61% in the untreated diabetic group but increased toward control levels with insulin therapy. Changes in the kidney weight of these animals paralleled the changes in GFR, which was increased in insulin-treated moderately hyperglycemic animals but unchanged in untreated diabetic rats. Uncontrolled experimental diabetes is a state of sodium retention and volume expansion, with an increase in plasma ANP and urinary cGMP levels and a decrease in PRA and plasma IGF-I. Despite these changes in sodium and volume status and vasoactive hormones, untreated STZ-D was not associated with an increase in GFR or kidney size. Hyperfiltration and increased kidney growth occurred in diabetic rats with moderate hyperglycemia during insulin therapy, whereas parameters of sodium and volume status reverted toward normal. Thus, changes in GFR cannot be explained solely by sodium and volume status, the renin-angiotensin system, ANP, or plasma IGF-I, but they may be more closely related to other factors, such as the level of glycemia, the direct effects of insulin, or factors controlling kidney growth.
Compensation by Fetal Erythrocytes of Plasma Glucose Changes in Rats
Authors: Guarner Verónica , Alvarez-Buylla Ramón
Published: September 2013

Changes in plasma glucose and glucose and glycogen content in fetal erythrocytes (FRBCs) were studied in rats between days 15 and 21 of gestation and in adult rats. Plasma and FRBC glucose concentrations increased during fetal life and were higher in erythrocytes than in plasma. Glycogen was higher in FRBCs than in adult erythrocytes and tended to decrease from day 15 to 19 of gestation and to increase again on day 21. When FRBCs were incubated in vitro in different glucose concentrations to study their capacity to compensate for changes in plasma glucose concentration, younger cells showed better glucose-buffering capacities. Glucose and glycogen levels in FRBCs increased when they were incubated in high-glucose medium, and the glycogen concentration reached was higher in the early fetal stage than by the end of gestation. Nevertheless, adult erythrocytes accumulated more glycogen in highglucose medium than cells from any of the fetalaged erythrocytes. When glucose was injected intraperitoneally into fetuses of different ages, there was an increase of 3.7 μM/ml in glucose concentration in blood from the umbilical artery and 2.5 μM/ml in blood from the umbilical vein. FRBCs buffered some of this change, as evident by an increase in glycogen content. Again, buffering capacity was greater for erythrocytes in younger fetuses. Epinephrine diminished glycogen concentration in venous FRBCs on days 19 and 21 of gestation even in hyperglycemia. Insulin diminished glucose concentration in arterial plasma on days 17 and 21 of gestation, but there were no changes in glucose and glycogen in FRBCs. FRBCs play an important role in glucose homeostasis, facilitating glucose transport in the placenta and increasing glucose delivery to other fetal tissues.
Limited Duration of Remission of Insulin Dependency in Children With Recent Overt Type I Diabetes Treated With Low-Dose Cyclosporin
Authors: Bougnères Pierre-François , Landais Paul , Boisson Catherine , Carel Jean-Claude , Frament Nathalie , Boitard Christian , Chaussain Jean-Louis , Bach Jean-François
Published: September 2013

Preliminary data from our group indicated that cyclosporin A induced frequent remissions of insulin dependency in a group of 40 insulin-dependent (type I) diabetic children if given at the onset of clinical manifestations of diabetes. We report a 2-yr analysis of the response to cyclosporin A in the group of 81 patients included in the initial study. As observed before, a remission could be obtained in most of the patients (65%) in association with a shorter duration of symptoms, less severe hyperglycemia, lower incidence of ketoacidosis, and higher plasma C-peptide concentrations. All remissions ended during the follow-up period after a mean ± SE duration of 316 ± 21 days (range 31–850 days). Two parameters were linked to the duration of remissions: the mean circulating level of cyclosporin during the first 3 mo and the duration of prediagnostic polyuria. We were unable to relate the end of a remission to variations in the cyclosporin regimen, titer of autoantibodies, or progression of β-cell failure. The euglycemic clamp technique revealed that insulin sensitivity decreases with time in patients not taking insulin. At 24 mo, the patients who had a remission of insulin dependency had better glycemic control, lower insulin dosages, and C-peptide levels two- to threefold higher than the nonremission patients and four- to sixfold higher than the historical control subjects. The cyclosporin regimen was well tolerated over the observed period: more specifically, serum creatinine remained unchanged, and kidney biopsies performed at 18–24 mo of treatment were within normal limits. We conclude that this immunosuppressive regimen given to patients with overt type I diabetes maintains a residual insulin secretion, which, however, does not allow >2-yr remissions of insulin dependency. It remains to be studied whether some preservation of β-cell function will thereafter be retained and whether this can improve the management and prognosis of the disease. It will also be necessary to test whether earlier diagnosis can ameliorate and prolong our results.
Diabetes and the myo-inositol Paradox
Authors: Loy Albert , Lurie Keith G , Ghosh Amal , Wilson Jeanne M , MacGregor Leslie C , Matschinsky Franz M
Published: September 2013

To test the general applicability of the hypothesis that diabetes mellitus causes increased polyol pathway activity, decreased tissue free myo-inositol, and resultant pathological changes in tissues susceptible to the ravages of diabetes, we measured glucose, sorbitol, and myo-inositol with quantitative histochemical techniques in layers of the cornea, the aortic myointima, the cardiac left ventricle and atrioventricular node (AVN), and retina and kidney after 19 days or 2 mo (mildly diabetic non-insulin-treated [MD] and severely diabetic insulin-treated [SD] groups) in the alloxan-induced diabetes model. In the aqueous humor, glucose rose linearly with increased serum glucose, sorbitol was markedly increased in the MD and SD groups, and myo-inositol did not change in any diabetic group. There was no change in glucose or sorbitol in aortic myointima in any group, but myo-inositol was decreased in 19-day diabetic rabbits by 26%, unchanged in MD rabbits but paradoxically increased by 60% in SD rabbits. Glucose, sorbitol, and myo-inositol increased in all three corneal layers in SD rabbits but only in epithelium and stroma in 19-day and MD rabbits. AVN glucose and sorbitol did not change in 19-day diabetic, MD, or SD diabetic rabbits. AVN myo-inositol was three times higher than ventricular myo-inositol and did not appear to change in SD rabbits. Retinal pigmented epithelium myo-inositol was decreased 30% in SD rabbits. Glomerular myo-inositol was also decreased, but not significantly, in SD rabbits. We conclude that the paradoxical increase in corneal and aortal myo-inositol raises fundamental questions about the general applicability of the myo-inositol-depletion hypothesis.
Sulfonylurea-Stimulated Glucose Transport Association With Diacylglycerollike Activation of Protein Kinase C in BC3H1 Myocytes
Authors: Cooper Denise R , Vila Maria C , Watson James E , Nair Govindan , Pollet Robert J , Standaert Mary , Farese Robert V
Published: September 2013

The extrapancreatic effects of sulfonylurea drugs include increased glucose uptake by certain peripheral tissues. To study this effect, we used BC3H1 myocytes, which are reported to respond to these drugs. Within 30 min, tolbutamide and glyburide increased [3H]-2-deoxyglucose uptake in a dose-dependent manner. The inactive analogue carboxytolbutamide had no effect on glucose transport. Because increases in glucose transport may be mediated by activation of the diacylglycerol-protein kinase C signaling system, we examined the effects of these drugs on lipid metabolism and protein kinase C activity. Unlike insulin, tolbutamide and glyburide failed to increase [3H]glycerol labeling of diacylglycerol or labeling of phospholipids by 32P. After 30 min of treatment with tolbutamide or glyburide, however, membraneassociated and cytosolic protein kinase C activity were each increased. When cells were treated with 12-O- tetradecanoylphorbol-13-acetate (TPA) for 48 h to deplete certain isoforms of protein kinase C, glyburide, tolbutamide, and acute TPA treatment failed to increase glucose uptake, suggesting that TPA and sulfonylureas operate through activation of a common pathway. The effect of glyburide was additive to TPA in stimulating glucose uptake at low but not high TPA concentrations. As with insulin and TPA, extracellular Ca2+ was not essential for sulfonylurea-stimulated glucose uptake. Staurosporine, a protein kinase C inhibitor, blocked glyburide-, tolbutamide-, and insulinstimulated glucose uptake. In intact cells, glyburide stimulated the phosphorylation of both 80,000-Mr and 40,000-Mr proteins, which are markers for protein kinase C activation. Addition of sulfonylureas directly to the protein kinase C assay system in vitro provoked dioleinlike effects, in that sensitivity of the enzyme to Ca2+ was increased. Our findings suggest that tolbutamide and glyburide increase glucose uptake in BC3H1 myocytes by a postreceptor mechanism, which may involve direct activation of protein kinase C.
Experimental Diabetes Increases Insulinlike Growth Factor I and II Receptor Concentration and Gene Expression in Kidney
Authors: Werner Haim , Shen-Orr Zila , Stannard Bethel , Burguera Bartolome , Roberts Charles T , LeRoith Derek
Published: September 2013

Insulinlike growth factor I (IGF-I) is a mitogenic hormone with important regulatory roles in growth and development. One of the target organs for IGF-I action is the kidney, which synthesizes abundant IGF-I receptors and IGF-I itself. To study the involvement of IGF-I and the IGF-I receptor in the development of nephropathy, one of the major complications of diabetes mellitus, we measured the expression of these genes in the kidney and in other tissues of the streptozocin-induced diabetic rat. The binding of 125I-labeled IGF-I to crude membranes was measured in the same tissues. We observed a 2.5-fold increase in the steady-state level of IGF-I–receptor mRNA in the diabetic kidney, which was accompanied by a 2.3-fold increase in IGF-I binding. In addition to this increase in IGF-I binding to the IGF-I receptor, there was also binding to a lower-molecular-weight material that may represent an IGF-binding protein. No change was detected in the level of IGF-I–peptide mRNA. Similarly, IGF-II–receptor mRNA levels and IGF-II binding were significantly increased in the diabetic kidney. IGF-I– and IGF-II-receptor mRNA levels and IGF-I and IGF-II binding returned to control values after insulin treatment. Because the IGF-I receptor is able to transduce mitogenic signals on activation of its tyrosine kinase domain, we hypothesize that, among other factors, high levels of receptor in the diabetic kidney may also be involved in the development of diabetic nephropathy. Increased IGF-II–receptor expression in the diabetic kidney may be important for the intracellular transport and packaging of lysosomal enzymes, although a role for this receptor in signal transduction cannot be excluded. Finally, the possible role of IGF-binding proteins requires further study.
Effect of FK 506 on Spontaneous Diabetes in BB Rats
Authors: Murase Noriko , Lieberman Irving , Nalesnik Michael A , Mintz Daniel H , Todo Satoru , Drash Allan L , Starzl Thomas E
Published: September 2013

From days 30–120 after birth, 59 BB rats were treated with water (n = 20) or FK 506 in intragastric doses of 1 mg · kg−1 · day−1 (n = 19) or 2 mg · kg−1 day−1 (n = 20). Diabetes developed in 75,15, and 0% of the 3 groups, respectively. Animals protected from diabetes by FK 506 had normal intraperitoneal glucose tolerance tests, virtual absence histopathologically of autoimmune insulitis, and normal pancreatic insulin content. Forty-five to 75 days after stopping FK 506, ∼75% of the rats that were diabetes free at 120 days remained so.
Human Insulin-Receptor Gene
Authors: Seino Susumu , Seino Mitsuko , Bell Graeme I
Published: September 2013

The human insulin-receptor (hINSR) gene spans a region of > 120,000 base pairs (bp) on the short arm of chromosome 19. It is comprised of 22 exons or coding regions that vary in size from 36 to >2500 bp. To a large degree, the introns appear to divide the hINSR gene into segments that encode structural and/or functional elements of the hINSR protein. The exonintron organization of the hINSR gene provides a clue to the evolutionary history of this gene and suggests that it is a mosaic constructed from protein-coding regions recruited from other genes. Eight mutations in the hINSR gene that result in expression of structurally abnormal proteins have been described. These mutations are associated with insulin resistance and provide insight into the role of the hINSR gene in the development of diabetes mellitus
Defective Free-Fatty Acid and Oxidative Glucose Metabolism in IDDM During Hypoglycemia: Influence of Glycemic Control
Authors: Caprio Sonia , Amiel Stephanie , Tamborlane William V , Gelfand Robert A , Sherwin Robert S
Published: September 2013

To examine the impact of diabetes and its treatment on plasma free-fatty acid (FFA) and oxidative fuel metabolism during hypoglycemia, we combined indirect calorimetry with [3-3H]glucose during a 4-h low-dose insulin infusion (plasma insulin ∼2-fold above basal) in six poorly controlled and nine wellcontrolled insulin-dependent diabetes mellitus (IDDM) patients and in six healthy subjects. Diabetic subjects received insulin overnight to maintain euglycemia before study. Although free-insulin levels and counterregulatory hormone responses were similar, the plasma glucose fall was more pronounced in wellcontrolled diabetic subjects. In well-controlled diabetic and healthy subjects, the small increment in insulin rapidly suppressed plasma FFA and fat oxidation by ∼50% and stimulated carbohydrate oxidation by ∼80%. In contrast, plasma FFA levels did not fall in poorly controlled diabetic subjects, and glucose oxidation was not stimulated. To determine whether this resistance to the antilipolytic effect of insulin occurs in the absence of hypoglycemic counterregulation, we used a sequential low-dose euglycemic insulin clamp (0.2, 0.3, and 0.5 mU · k g−1 · mirr1). In healthy subjects, plasma FFA was nearly maximally suppressed at the lowest insulin dose. In contrast, plasma FFA remained persistently elevated in poorly controlled diabetic subjects at each insulin dose. However, the insulin dose-response curve for suppression of plasma FFA was near normal in well-controlled subjects. We conclude that poorly controlled IDDM diabetic patients are resistant to the antilipolytic effects of insulin and show impaired stimulation of glucose oxidation during insulin-induced hypoglycemia. Amelioration of these defects in well-controlled patients may be another factor contributing to the higher risk of hypoglycemia during intensified insulin therapy.
Altered Steady-State mRNA Levels of Basement Membrane Proteins in Diabetic Mouse Kidneys and Thromboxane Synthase Inhibition
Authors: Ledbetter Steven , Copeland E Jill , Noonan Douglas , Vogeli Gabriel , Hassell John R
Published: September 2013

We examined steady-state levels of mRNA encoding type IV collagen, B, chain of laminin, and the basement membrane heparan sulfate proteoglycan in the kidney cortex of a mouse model (KKAy) of non-insulindependent diabetes. mRNAs encoding laminin B, and the proteoglycan were unchanged in kidneys taken from diabetic mice with demonstrable basement membrane thickening. mRNA levels for type IV collagen, in contrast, were significantly elevated (2-fold) in diabetic mice concurrent with but not preceding morphologically thickened basement membranes. There was a negative correlation between a ratio of proteoglycan/type IV collagen and levels of albuminuria in the diabetic mice. No correlation was noted with laminin. We also examined the effects of inhibiting the synthesis of thromboxane, a potent vasoconstrictor, on the steady-state levels of type IV collagen in the diabetic mice. Inhibition of thromboxane stopped the progression of albuminuria and prevented an increase in type IV collagen mRNA levels. We conclude that basement membrane thickening in diabetes, a hallmark of diabetic nephropathy, is partly a consequence of an unbalanced increase in the production of type IV collagen. The relative decrease in proteoglycan production may contribute to chronic albuminuria.
Induction of Insulin Resistance In Vivo by Amylin and Calcitonin Gene–Related Peptide
Authors: Molina Joseph M , Cooper Garth J S , Leighton Brendan , Olefsky Jerrold M
Published: September 2013

During hyperinsulinemic glucose-clamp studies, intravenous infusion of calcitonin gene-related peptide (CGRP) in rats antagonized the ability of insulin to stimulate peripheral glucose disposal by 52% (196 ± 7.2 vs. 105 ± 10.5 μmol · kg−1 · min−1, P < 0.05) and to inhibit hepatic glucose output by 54% (P < 0.01). CGRP also inhibited the in vitro effects of insulin to stimulate hexose uptake in cultured BC3H1 myocytes at all insulin concentrations studied. Amylin is a peptide isolated from amyloid deposits in pancreatic islets of type II (non-insulin-dependent) diabetic subjects, is present in normal β-cells, and bears a striking homology to CGRP. When synethetic human amylin was infused during clamp studies, it inhibited the ability of insulin to stimulate glucose disposal by 56% (96.9 ± 9.4 vs. 42.4 ± 5.0 μmol · kg−1 · min−1, P < 0.05) and to suppress hepatic glucose output by 64%. Therefore, amylin and CGRP can cause insulin resistance in vivo and may be implicated in insulinresistant states such as type II diabetes mellitus.
High Frequency of Aspartic Acid at Position 57 of HLA-DQ β-Chain in Japanese IDDM Patients and Nondiabetic Subjects
Authors: Awata Takuya , Kuzuya Takeshi , Matsuda Ayako , Iwamoto Yasuhiko , Kanazawa Yasunori , Okuyama Machiko , Juji Takeo
Published: September 2013

The HLA-DQ β-chain (DQB1) genes of 72 Japanese patients with insulin-dependent diabetes mellitus (IDDM) and 85 control subjects were studied with polymerase chain-reaction (PCR) amplification and allele-specific oligonucleotide hybridization. DQw4 (DQBBIank) and DQw9 (DQB3.3) were increased in IDDM patients compared with the control subjects, and DQB1.2, DQB1.9, and DQw7 (DQB3.1) were decreased. Thirty-five (48.6%) IDDM patients had both alleles carrying an aspartic acid at position 57 of the DQ β-chain (Asp 57), 35 (48.6%) were Asp 57/non-Asp 57 heterozygous, and 2 (2.8%) had non-Asp 57 alleles only. Of 85 control subjects, the respective values for these three genotypes were 49 (57.6%), 29 (34.1%), and 7 (8.2%), respectively. The high frequency of Asp 57 alleles in both IDDM and control subjects contrasts with data for Whites. Therefore, the Asp 57 hypothesis that the presence of an aspartic acid at position 57 of DQ β-chain provides protection against developing IDDM is not tenable for Japanese IDDM patients. The DRB1 gene, particularly position 57 of the DR β-chain, may contribute to IDDM susceptibility in Japanese.
Incidence of Type II Diabetes in Mexican Americans Predicted by Fasting Insulin and Glucose Levels, Obesity, and Body-Fat Distribution
Authors: Haffner Steven M , Stern Michael P , Mitchell Braxton D , Hazuda Helen P , Patterson Judith K
Published: September 2013

Few data exist on predictors of non-insulin-dependent (type II) diabetes mellitus. We examined body mass index (BMI), ratio of subscapular-to-triceps skin fold (centrality index), and fasting glucose and insulin concentrations as predictors of decompensation to type II diabetes in Mexican Americans, a population at high risk for this disorder. Twenty-eight of 474 initially nondiabetic Mexican Americans developed type II diabetes after 8 yr of follow-up. Converters to diabetes were older and had higher BMIs, centrality indices, and fasting glucose and insulin concentrations than nonconverters. Subjects in the highest quartile of the insulin distribution had 6.6 times the risk of developing type II diabetes as subjects in the remaining three quartiles combined (95% confidence interval [CI] = 3.14–13.7). In multivariate analysis, fasting glucose (odds ratio [OR] = 5.80, 95% CI = 2.57–13.1) and insulin (OR = 3.12, 95% CI = 1.36–7.14) remained significantly related to conversion to diabetes. However, BMI and centrality index, which were significantly related to conversion in the univariate analysis, were no longer significant in the multivariate analysis once glucose and insulin concentrations were taken into consideration, suggesting that the effect of these variables may be mediated by insulin resistance. Nearly half of the incident cases developed in a subset of the population who were simultaneously in the highest quartile of both fasting insulin and glucose concentrations (population-attributable risk 44.2%). Our results support the insulin resistance/pancreatic exhaustion theory of type II diabetes.
Renal Kallikrein and Hemodynamic Abnormalities of Diabetic Kidney
Authors: Harvey John N , Jaffa Ayad A , Margolius Harry S , Mayfield Ronald K
Published: September 2013

The relationship between renal hemodynamic abnormalities and renal kallikrein activity was studied in streptozocin-induced diabetic rats. Diabetic rats were either not treated with insulin and had plasma glucose levels >400 mg/dl (severely hyperglycemic diabetic [MD]) or were treated with 1.5–1.75 U/day protamine zinc insulin and had glucose levels of 200–300 mg/dl (moderately hyperglycemic diabetic [MD]). In SD rats, kidney tissue level and excretion of active kallikrein were reduced after 3 wk compared with age-matched nondiabetic control rats (tissue, 11.7 ± 1.9 vs. 20.5 ± 1.8 ng/mg protein, P <0.005; urine, 126 ± 12vs. 179 ± 10 μg/24 h, P <0.05). Glomerular filtration rate (GFR) was not significantly lower (2.77 ± 0.60vs. 3.02 ± 0.56 ml/min). In MD rats, kidney tissue level and excretion of active kallikrein were increased after 5 wk compared with age-matched nondiabetic control rats (tissue, 28.4 ± 1.3 vs. 23.3 ± 1.7 ng/mg protein, P < 0.05; urine, 289 ± 16 vs. 196 ± 13μg/24 h, P < 0.001). In MD rats, GFR and RPF were increased (3.80 ± 0.11 and 8.04 ± 0.17 ml/min, respectively) compared with control rats (3.22 ± 0.05 and 7.28 ± 0.09 ml/min, P < 0.001). Treatment of MD rats with a kallikrein inhibitor reduced GFR and RPF to levels similar to those of nondiabetic control rats. With recent evidence that kallikrein and kinins have a renal paracrine role in regulating vascular resistance, our findings suggest that altered kallikrein activity may contribute to the renal hemodynamic and filtration abnormalities in diabetes.
Chronic Exposure to High Glucose and Impairment of K+-Channel Function in Perifused Rat Pancreatic Islets
Authors: Purrello Francesco , Vetri Mario , Vinci Carmela , Gatta Concetta , Buscema Massimo , Vigneri Riccardo
Published: September 2013

Prolonged exposure to high glucose levels impairs the ability of pancreatic islets to secrete insulin as a response to that stimulus. Because glucose, like other insulin secretagogues, elicits insulin secretion by inhibiting the ATP-sensitive K+ channels, in this study, we investigated the effect of prolonged (24-h) exposure of rat pancreatic islets to high (16.7 mM) glucose concentration on 86Rb efflux (used as a tracer for K+). The data obtained indicate that islets exposed to high glucose concentration have impaired function of the glucose-sensitive K+ channel, this phenomenon is temporarily related to a defective response of glucose-induced insulin release, and these alterations are reversible.
Islet Mass and Function in Diabetes and Transplantation
Authors: Weir Gordon C , Bonner-Weir Susan , Leahy John L
Published: September 2013

The concept of pancreatic β-cell mass is fundamental to the understanding of normal metabolism, the pathogenesis of diabetes, and the transplantation of β-cell tissue. The amount of β-cell tissue present in the pancreas is a major determinant of the quantity of insulin that can be secreted, and its mass will vary according to the size of the individual and the degree of insulin resistance present. Not all insulin-producing cells are the same, and the dimensions of this heterogeneity remain to be defined. Pancreatic β-cell mass is markedly reduced in insulin-dependent diabetes mellitus and moderately reduced in non-insulin-dependent diabetes mellitus. In both forms of diabetes, there are qualitative and quantitative abnormalities of insulin secretion that cannot be explained entirely by changes in β-cell mass. The amount of β-cell tissue needed for successful transplantation has only been partially defined. Segmental (∼50% of the pancreas) transplantation can normalize plasma glucose levels in humans. Difficulty obtaining sufficient amounts of β-cell tissue is expected to remain a barrier to successful islet transplantation for the immediate future. More should be learned about the function and fate of grafted islet cells.
Effects of ω-3 Fish Oils on Plasma Lipids, Lipoprotein Composition, and Postheparin Lipoprotein Lipase in Women With IDDM
Authors: Bagdade John D , Buchanan Wilfred E , Levy Richard A , Subbaiah Papasani V , Ritter Mary C
Published: September 2013

Because the apparent reduction in cardiovascular risk noted in nondiabetic populations that ingest diets rich in marine lipids containing ω-3 fatty acids is believed to result in part from their capacity to modify the composition and physicochemical behavior of lipoproteins, we sought to determine whether dietary supplementation with marine lipids might favorably affect lipoprotein composition in insulin-dependent diabetes mellitus (IDDM). Eight normolipidemic IDDM women (mean ± SD age 29.8 ± 4.7 yr) were studied before and 3 mo after receiving a marine-lipid concentrate (Super-EPA) containing 6 g ω-3 fatty acids and a total of 12 mg of cholesterol daily. Weight, insulin requirements, and glycosylated hemoglobin remained stable. After treatment, mean ± SD plasma triglyceride (TG) levels fell (before, 81.7 ± 22 mg/dl; after, 69.19 ± 17; P < 0.025). High-density lipoprotein2 (HDL2) cholesterol (before, 10.98 ± 5.45 mg/dl; after, 18.43 ± 7.93; P < 0.01), its major apolipoprotein A-I (apoAl), and the major phospholipids (sphingomyelin and lecithin) all rose significantly. ApoB and plasma and low-density lipoprotein cholesterol levels and HDL3 composition were unchanged. Postheparin hepatic and lipoprotein lipase activities were unaffected by marine lipids. These data indicate that women with IDDM experience apparently beneficial effects on TG and HDL2 from dietary supplementation with ω-3 fatty acids administered in a low-cholesterol–containing oil without adversely affecting overall diabetes management. If these changes in lipoprotein concentration and composition prove to have antiatherogenic consequences and are free of long-term toxicity, these agents may have a role in the therapy of IDDM patients.
Changes in Skeletal Muscle Contractile Properties in Streptozocin-Induced Diabetic Rats and Role of Polyol Pathway and Hypoinsulinemia
Authors: Cameron Norman E , Cotter Mary A , Robertson Sharon
Published: September 2013

Functional changes in slow-twitch soleus and fast-twitch extensor digitorum longus muscles were assessed after 2 mo of streptozocin-induced diabetes in rats. For soleus, there was a slowing of twitch times both for contraction and relaxation and a reduction of maximum tetanic relaxation rate. There was little effect on strength performance assessed by maximal tetanic tension production. Treatment with the aldose reductase inhibitor ponalrestat largely prevented relaxation defects but had little effect on contraction. For the fast muscle, twitch times were relatively unaffected, but maximum tetanic relaxation rate was reduced. In addition, tetanic tension output decreased. These changes were largely prevented by ponalrestat treatment. The effects of partial insulin therapy were also investigated. This regimen reduced hypoinsulinemia, but sufficient hyperglycemia remained to stimulate the polyol pathway. It prevented the slowing of soleus twitch contraction but had no effect on relaxation. For extensor digitorum longus, insulin produced further deleterious effects on tetanic tension and maximum relaxation rate, which were antagonized by ponalrestat. A 1% dietary myo-inositol supplement had little effect on contractile function in slow or fast muscles. It was concluded that polyol-pathway activity is an important factor underlying skeletal muscle functional changes in diabetes, probably acting through disruption of Ca2+ handling. Hypoinsulinemia was considered a secondary factor causing atrophy, particularly of fast muscles. There was no evidence of effects dependent on neuropathy.
Insulin Independence After Islet Transplantation Into Type I Diabetic Patient
Authors: Scharp David W , Lacy Paul E , Santiago Julio V , McCullough Christopher S , Weide Lamont G , Falqui Luca , Marchetti Piero , Gingerich Ronald L , Jaffe Allan S , Cryer Philip E , Anderson Charles B , Flye M Wayne
Published: September 2013

Effective clinical trials of islet transplantation have been limited by the inability to transplant enough viable human islets into patients with type I (insulin-dependent) diabetes mellitus to eliminate their exogenous insulin requirement. We report the first type I diabetic patient with an established kidney transplant on basal cyclosporin immunosuppression who was able to eliminate the insulin requirement after human islet transplantation into the portal vein. We successfully isolated ∼800,000 islets that were 95% pure from 1.4 cadaver pancreases containing 121 U of insulin. Islets were proven viable by in vitro insulin response to glucose challenge. After 7 days of 24°C culture, the islets were transplanted into the portal vein under local anesthesia. Seven days of Minnesota antilymphoblast globulin (20 mg/kg) administration followed the islet transplantation, with maintenance of the cyclosporin. Blood glucose was kept under strict control via intravenous insulin for 10 days posttransplantation, when all insulin therapy was stopped. Off insulin, the average 24-h blood glucose level remained <150 mg/dl, with the fasting glucose level at 115 ± 6 mg/dl and the 2-h postprandial level at 141 ±8 mg/dl for 22 days posttransplantation (the time of this study). The C-peptide values post-Sustacal testing, although initially rising slower, exceeded the normal range, with peak values of 1.0–1.8 pmol/ml. This preliminary result represents the first essential step required to determine the feasibility of islet transplantation by future clinical trials.