bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibodies to Insulin-Like Growth Factor I Receptors in Diabetes and Other Disorders
Authors: Tappy Luc , Fujita-Yamaguchi Yoko , LeBon Thomas R , Boden Guenther
Published: September 2013

A newly developed immunoprecipitation assay, with 125I-labeled highly purified human placental insulin-like growth factor I (IGF-I) receptor, was used to search for IGF-I-receptor antibodies in human sera. Eleven of 141 patient sera tested (7.8%) immunoprecipitated labeled IGF-I receptor. Immunoprecipitation was comparable with sera and IgG prepared from these sera. Seven of the 11 sera (3 of 31 with rheumatic disorders, 3 of 48 with non-insulin-dependent diabetes, and 1 of 52 with insulin-dependent diabetes) failed to inhibit IGF-I binding to human placental membranes and thus contained non-binding-inhibitory IGF-I-receptor antibodies. Their pathophysiological function remained uncertain. The remaining 4 sera (2 of 3 with type B severe insulin resistance, 1 of 7 with polycystic ovary syndrome (PCO), and 1 of 31 with rheumatic disorders) inhibited IGF-I binding. Plasma IGF-I concentrations were elevated (663 and 802 ng/ml, respectively) in 2 patients (1 with PCO and another with systemic lupus erythematosus) with binding-inhibitory IGF-I-receptor antibodies, suggesting IGF-I resistance that was probably mediated by the IGF-I-receptor antibodies. In conclusion, we identified two species of human IGF-I-receptor antibodies. Sera from 7 of 141 patients tested contained IgG autoantibodies that bound to the IGF-I receptor at a locus different from the IGF-I binding site and did not inhibit IGF-I binding. Sera from 4 of 141 patients contained antibodies that bound to the IGF-I receptor at or near the IGF-I binding site, inhibited IGF-I binding, and probably caused IGF-I resistance.
Suppression of Sleep-Induced Growth Hormone Secretion by Anticholinergic Agent Abolishes Dawn Phenomenon
Authors: Davidson Mayer B , Harris Michael D , Ziel Fred H , Rosenberg Carol S
Published: September 2013

The dawn phenomenon was evaluated in eight C-peptide-negative type I (insulin-dependent) diabetic patients on two occasions by measuring glucose concentrations every 30 min from 2400 to 0800 h while the subjects were receiving an insulin infusion (0.12 mU·kg−1 · min−1). In random order at 2230 h, they orally received either a sleeping medication alone or with 5.0 mg methscopolamine bromide, an anticholinergic agent. The peak growth hormone (GH) concentrations (ng/ml ± SE) after sleep were markedly inhibited by methscopolamine (4.7 ± 2.6 vs. 23.0 ± 9.2). During the control night, the late (0400–0800 h) glucose response (area under curve but above 0400 h value) was significantly higher (P < .02) than the early (2400–0400 h) glucose response (area under curve but above 2400 h value). After methscopolamine, the early and late glucose responses were virtually identical. The anticholinergic agent did not affect glucagon levels, overnight urinary catecholamine excretion, or the diurnal cortisol concentrations. The total area under the free fatty acid (FFA) curves was significantly (P < .05) reduced by methscopolamine. We conclude that sleep-induced GH secretion may cause the dawn phenomenon by increasing FFA levels. Oral administration of methscopolamine at bedtime is a simple pharmacological approach that could test the clinical importance of the dawn phenomenon.
Evolution of Abnormal Insulin Secretory Responses During 48-h In Vivo Hyperglycemia
Authors: Leahy John L , Weir Gordon C
Published: September 2013

Recent in vitro studies have shown that insulin release caused by continuous exposure to high glucose concentration markedly falls within a few hours. We wanted to determine if a similar effect occurs in vivo with chronic intravenous infusions in normal rats. Male CD rats (200–250 g) were infused with 50% glucose at 2 ml/h for 6, 14, 24, or 48 h, whereas controls received 0.45% NaCl, and insulin responses were tested with the in vitro isolated perfused pancreas. Plasma glucose averaged 352 ± 20 mg/dl after 4 h and 396 ± 11 mg/dl after 24 h versus 137 ± 5 mg/dl in controls; plasma insulin at the same times was 8.94 ± 1.44 and 12.1 ± 2.62 ng/ml versus 1.69 ± 0.19 ng/ml in controls. The incremental insulin response caused by an increase in perfusate glucose from 2.8 to 16.7 mM was not significantly reduced after 24 h of glucose infusion; in contrast, paradoxical suppression was seen after 48 h. A second protocol examined glucose potentiation by giving 10 mM arginine at 2.8 and 16.7 mM glucose; a hyperresponse to arginine at the lower glucose level was present after just 14 h of infusion. Therefore, these results do not support the hypothesis that β-cells lose their sensitivity to glucose within hours of being exposed to higher than normal glucose concentrations.
Prevalence of Diabetes in Israel: Epidemiologic Survey
Authors: Stern Ervin , Blau Joanna , Rusecki Yael , Rafaelovsky M , Cohen Margo P
Published: September 2013

A survey of 4660 Israeli adults aged 30–65 yr revealed an overall diabetes prevalence of 4.1%. Prevalence was slightly lower in women (3.5%) than in men (4.3%), rose with age, and was highest in the group >60 yr old (10.3%). In ∼40% of the diabetic subjects, the diagnosis of diabetes was made as a result of the screening program. Association with a family history of diabetes, obesity, and the presence of other diseases was greater in diabetic than in nondiabetic subjects. The prevalence of diabetes differed among different segments of the survey population when classified according to country of origin, being lowest in African and Asian (1.2%), intermediate in American and European (4.9%), and highest in Israeli born (5.5%); this order of prevalence is the reverse of that reported in earlier surveys. The results indicate that the overall diabetes prevalence in Israel, and that within the European- and American-born segment, is comparable to that reported in other westernized societies. The findings also suggest that environmental factors contribute to the phenotypic expression of the non-insulin-dependent genotype(s) but that the influence of such factors varies with different genetic backgrounds.
Autoantibodies to Insulin Are Present in Sera of Patients With Autoimmune Thyroid Disease
Authors: Nuovo Jennifer A , Baker James R , Wartofsky Leonard , Lukes Yvonne G , Burman Kenneth D
Published: September 2013

It has been clinically suspected that patients with autoimmune thyroid disease are at an increased risk of developing other autoimmune diseases later in life. To determine the presence and potential importance of a more generalized deregulation of immune response in patients with Grave's disease and Hashimoto's disease, sera from 33 patients with Graves' disease and 16 patients with Hashimoto's disease were screened for the presence of anti-insulin antibodies and anti-insulin-receptor antibodies. An enzyme-linked immunosorbent assay was used to identify the presence of IgG against human insulin. The optical density indicating the presence of IgG against insulin in sera from patients with Graves' disease averaged .172 ± .024 (mean ± SE; range .010–.802), compared to the mean normal value of .098 ± .0009 (range .012–.238) in 33 control subjects. Ten of 33 patients with Graves' disease had values > .200, whereas control sera values were < .200 in all but one case (P < .005, Graves' sera vs. controls). The sera from patients with Hashimoto's disease had a mean optical density of .110 ± .016, with 15 of 16 values between .010 and .200. These values were not significantly different from controls with an insulin-binding inhibition assay. Anti-insulin-receptor antibodies were not detected in any of 33 patients with Graves' disease, and cytoplasmic islet cell antibodies were not detected in sera from seven patients with Graves' disease who had insulin-binding antibodies. These data support the hypothesis that the immunologic response in autoimmune thyroid disease may be more heterogeneous and polyclonal than previously believed.
Diabetes Prevention in BB Rats by Frequent Blood Withdrawal Started at a Young Age
Authors: Yale Jean-François , Grose Mark , Seemayer Thomas A , Marliss Errol B
Published: September 2013

The BB rat diabetic syndrome has been prevented by various immunosuppressive and reconstitution measures. We observed an effect of multiple blood samplings on diabetes incidence and examined its immunological correlates. Individual litters were divided into two groups; one was sampled and the other was sham sampled as the control group. Sixty-four diabetes-prone and 59 non-diabetes-prone rats were studied. The sampled rats had blood removed at 15 (28% of total blood volume), 30 (30%), 50 (21%), 75 (16%), and 120 days of age. The sham-sampled control rats had blood removed only at 120 days of age. The incidence of diabetes in the sampled group was markedly lower than that of their sham-sampled littermates (22 vs. 78%). This result was associated with a correction of their OX19+ (pan-T-lymphocytes) and W3/25+ (helper/inducer) T-lymphocyte-number defects. An increase in lymphocyte subsets was also seen in the non-diabetes-prone BB rats, significant for all but the OX19+ cells. Islet pathology and pancreatic insulin content were consistent with metabolic outcomes. The effect of blood withdrawal thus has implications for understanding the pathogenesis of both the diabetes syndrome and the lymphopenia of the BB rat. Furthermore, it suggests that a stimulation of lymphopoiesis by blood withdrawal (analogous to that of erythropoiesis) may be a hitherto unrecognized physiological response in normal animals.
Reovirus Infection Enhances Expression of Class I MHC Proteins on Human β-Cell and Rat RINm5F cell
Authors: Campbell Iain L , Harrison Leonard C , Ashcroft Robert G , Jack Ian
Published: September 2013

Viruses are implicated in the pathogenesis of β-cell destruction in type I (insulin-dependent) diabetes. The aim of our study was to investigate whether reovirus 1 or reovirus 3, which are known to infect β-cells and induce autoimmunity in susceptible mice, could alter the expression of the major histocompatibility complex (MHC) proteins by human β-cells and rat insulinoma RINm5F cells. Forty-eight hours after infection of either human β-cells or RINm5F cells with reovirus 1 or reovirus 3, cytopathic effects were noted. By flow-cytofluorometric analysis, infected RINm5F cells exhibited a seven- to eightfold increase in the surface expression of class I MHC proteins. Upregulation of class I MHC proteins on reovirus 3-infected RINm5F cells was inhibited by 80% after preexposure of the virus to reovirus 3 antiserum. When analyzed by double-indirect immunofluorescence microscopy, human β-cells infected with reoviruses 1 or 3 also exhibited markedly increased levels of class I MHC proteins. Reovirus infection of human β-cells or RINm5F cells was not accompanied by the induction of class II MHC proteins. These findings suggest that 1) in addition to direct cytopathic effects, reovirus infection may contribute to β-cell destruction by increasing expression of class I MHC proteins and therefore reactivity with cytotoxic T-lymphocytes; and 2) some viruses may increase MHC protein expression independent of and before the action of cytokines (e.g., interferon-γ and tumor necrosis factor) released by immunoinflammatory cells.
Allotransplantation of Dispersed Single Pancreatic Endocrine Cells in Diabetic Rats
Authors: Tze Wah Jun , Tai Joseph
Published: September 2013

Dispersed pancreatic endocrine cells (PECs) were recently shown to survive indefinitely in the brain of allogeneic diabetic rat recipients across the major histocompatibility barrier without immunosuppression. Purified PECs (2−3 × 106 cells) prepared from Wistar rat islets were transplanted in 10 different sites in streptozocin-induced diabetic ACI rats. Blood glucose and body weight changes were monitored throughout the study. PEC isografts (n = 5) and allografts (n = 6) were nonfunctional when transplanted in intramuscular, intravenous, and intrahepatic sites. When transplanted intraportally (n = 6) and intraperitoneally (n = 6), similar grafts were functional but had a short survival period (6.6 ± 1.5 and 15.3 ± 16.6 days, respectively). Prolonged graft survival in some recipients was observed when kidney capsule [5, 9, 10, 240, 282, and 300 (2 rats) days], omentum pocket (7, 8, 10, 90, 105, 154, 155, and 157 days), and testis (7, 8, 12, 150, 230, and 234 days) were the transplantation sites. Permanent graft survival was achieved in 20 of 20 recipients with intracerebral transplantation and 21 of 22 recipients with intrathecal transplantation. These findings confirm that dispersed single PECs can be transplanted as a permanent functional graft and can normalize the hyperglycemia of the diabetic recipients. The duration of PEC graft survival is variable and depends on the transplantation site. Both the cerebral cortex and subarachnoid space, which are immunologically privileged sites, have provided the best allograft protection.
Epidemiology of Persistent Proteinuria in Type II Diabetes Mellitus: Population-Based Study in Rochester, Minnesota
Authors: Ballard David J , Humphrey Linda L , Melton L Joseph , Frohnert Peter P , Chu Chu-Pin , O'Fallon W Michael , Palumbo Pasquale J
Published: September 2013

Clinical risk factors for nephropathy were assessed in a population-based study of Rochester, Minnesota, residents with diabetes mellitus initially diagnosed between 1945 and 1969 (incidence cohort). The 1031 Rochester residents with non-insulin-dependent diabetes mellitus (NIDDM) were followed through their complete medical records in the community to 1 January 1982. The prevalence of persistent proteinuria was 8.2% at the diagnosis of NIDDM. Among those initially free of persistent proteinuria, the subsequent incidence was 15.3/1000 person-yr. Twenty years after the diagnosis of diabetes, the cumulative incidence of persistent proteinuria was 24.6%. A proportional hazards model identified the following risk factors for persistent proteinuria in NIDDM: elevated initial fasting blood glucose (P < .01); older age at onset of diabetes (P < .01); male gender (P = .05); and presence of macrovascular disease (P = .05), diabetic retinopathy (P = .05), or glycosuria (P = .07) at the diagnosis of diabetes. Separate analyses controlling for attained age indicated no association between duration of NIDDM and the incidence of persistent proteinuria. Stratified analysis of the two most significant risk factors (fasting blood glucose and age) indicated that hyperglycemia was a stronger risk factor for proteinuria in younger diabetic subjects, perhaps because of a competing risk of death in the elderly diabetic patient. In contrast to a recently described decreasing secular trend of proteinuria in Danish insulin-dependent diabetes mellitus patients, there was no decrease over the past 40 yr in proteinuria risk in this NIDDM incidence cohort.
In Vitro Studies of Insulin Resistance in Patients With Lipoatrophic Diabetes: Evidence for Heterogeneous Postbinding Defects
Authors: Magré Jocelyne , Reynet Christine , Capeau Jacqueline , Blivet Marie-José , Picard Jacques
Published: September 2013

We studied the binding and action of insulin in cultured fibroblasts from six patients with lipoatrophic diabetes and marked in vivo insulin resistance and from seven control subjects. The binding of insulin was not altered, which corresponds well with studies with circulating erythrocytes. Similarly, the action of the hormone on amino acid uptake (estimated by active transport of aminoisobutyric acid) was comparable in patient and control cells. Conversely, studies concerning the effect of insulin on glucose transport (estimated by facilitated diffusion of 2-deoxyglucose) or glycogen synthesis (estimated by incorporation of glucose into cellular glycogen) revealed the presence of heterogeneous alterations among the different patient cell lines. However, although the nature of the defect(s) varied among the patients, alterations in glucose metabolism were present in all cases. These data suggest the presence of primary postbinding defects in glucose cellular pathways that give rise to insulin resistance in cells from lipoatrophic diabetic patients.
Role of Enhanced Arachidonate Availability Through Phospholipase A2 Pathway in Mediation of Increased Prostaglandin Synthesis by Glomeruli From Diabetic Rats
Authors: Craven Patricia A , Patterson Mark C , DeRubertis Frederick R
Published: September 2013

Prostaglandin E2 (PGE2) production by superfused glomeruli from rats made diabetic for 2 wk by streptozocin injection is twofold higher than that by glomeruli from normal rats. The higher rates of PGE2 production by glomeruli from diabetic rats are associated with higher levels of labeled free arachidonate in glomeruli prelabeled with [3H]arachidonate, both basally and after stimulation with Ca2+ ionophore A23187. The difference between release of labeled arachidonate from phospholipids of diabetic versus normal glomeruli is likely underestimated by measurements of arachidonate alone due to more rapid incorporation of released arachidonate into triacylglycerol of diabetic glomeruli. A23187 induced a fall in labeled phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol in glomeruli that had been prelabeled with [3H]arachidonate and also induced a reduction in the mass of these phospholipids. Consistent with the higher levels of labeled arachidonate, the reduction in both labeled phospholipids and phospholipid mass with A23187 was greater in glomeruli from diabetic than normal rats. Furthermore, the reduction in labeled phospholipids and phospholipid mass with A23187 was largely (62–80%) accounted for by a fall in phosphatidylcholine plus phosphatidylethanolamine in glomeruli from both normal and diabetic rats. These results suggest a primary role for phospholipase A2 in A23187 actions on glomerular arachidonate release in normal rats and for the higher levels of arachidonate found in glomeruli from diabetic rats. Nevertheless, A23187 also stimulated the production of inositol phosphates—a measure of cellular phospholipase C activity. The increases in inositol phosphate production induced by A23187 were greater in glomeruli from diabetic than normal rats. However, the difference in inositol phosphate production between the two groups was abolished by indomethacin, suggesting that they were secondary to the enhanced prostanoid production by the diabetic glomeruli. Studies of phospholipase A2 and C activities in subcellular fractions of glomerular homogenates also supported a role for enhanced phospholipase A2 activity in the mediation of increased availability of arachidonate for prostaglandin synthesis in glomeruli from diabetic versus normal rats. Thus, phospholipase A2 activity was twofold higher in glomeruli from diabetic than normal rats, whereas phospholipase C activity was not different between the two groups. Treatment of diabetic rats with insulin prevented the rise in glomerular phospholipid A2 otherwise seen in these rats.
Autonomic and Somatosensory Nerve Function After 2 Years of Continuous Subcutaneous Insulin Infusion in Type I Diabetes
Authors: Jakobsen Johannes , Christiansen Jens S , Kristoffersen Inger , Christensen Cramer K , Hermansen Kjeld , Schmitz Antia , Mogensen Carl Erik
Published: September 2013

Autonomic and somatosensory nerve function was studied in 24 insulin-dependent diabetic subjects (aged 29 ± 7 yrs, diabetes duration 8 ± 4 yr) randomly allocated to either continuous subcutaneous insulin infusion (CSII; n = 12) or unchanged conventional insulin therapy (CIT; n = 12). Measures of glycemic control and somatosensory and autonomic nerve function were comparable in the two groups at the start. Glycemic control was significantly improved in the CSII group throughout study, whereas it remained unchanged in the CIT group. In the CIT group, vibratory perception threshold (VPT) of the great toe and the medial malleolus deteriorated, as did heart rate variation (HRV) at rest, at deep breathing (.05 < P < .06), and at standing. In contrast, CSII patients retained their VPT and HRV. Comparison of nerve function alterations during the 2-yr trial showed better preservation in CSII than in CIT patients of VPT in the great toe (0.8 ± 1.7 vs. −1.4 ± 1.9 V, P < .01) and the medial malleolus (1.5 ± 2.9 vs. −1.4 ± 1.8 V, P < .05) and of HRV at rest (10 ± 24 vs. −13 ± 22 ms, P < .05) and at standing (−0.01 ± 0.13 vs. −0.15 ± 0.16 ms, P < .05). We conclude that intensified glycemic control can favorably influence parasympathetic and somatosensory nerve function in insulin-dependent diabetes mellitus.
Circulating Anti-Immunoglobulin Antibodies in Recent-Onset Type I Diabetic Patients
Authors: Di Mario Umberto , Dotta Francesco , Crisa Laura , Anastasi Emanuela , Andreani Domenico , Dib Sergio A , Eisenbarth George S
Published: September 2013

Human sera from 51 recent-onset insulin-dependent (type I) diabetic patients and 47 unrelated control subjects were screened for the possible presence of circulating factors reacting with several anti-pancreatic islet monoclonal antibodies (MoAb.ISL) in solid-phase radioimmunoassay methods (the original goal being the detection of anti-idiotypic islet cell antibodies and/or specific islet cell antigen–bearing immune complexes). MoAbs from the parental myeloma cell line and purified immunoglobulins (Igs) from different animal species were controls. Type I diabetic sera showed significantly increased binding to MoAb.ISL-coated wells compared with normal subjects (P < .001). However, the same sera also tended to show a higher binding to the control (non–islet-related) MoAb. Sera from type I diabetic patients also reacted with horse, bovine, pig, rabbit, and goat IgG. Displacement of the binding has been obtained by F(ab′)2 and/or Fc fragments of IgG. Evidence has been obtained regarding a similar reaction with human IgM. All the sera were negative when tested for rheumatoid factor by nephelometry. The circulating antibodies described have been proven to be different from islet cell autoantibodies. An anti-Ig antibody is thus present in the sera of recent-onset diabetic patients and represents an additional immunological phenomenon with possible physiopathological and clinical significance.
ATP-Sensitive K+ Channels in Pancreatic β-Cells: Spare-Channel Hypothesis
Authors: Cook Daniel L , Satin Leslie S , Ashford Michael L J , Hales C Nicholas
Published: September 2013

Since their discovery in pancreatic β-cells, ATP-sensitive K+ channels in the cell membrane have been thought to mediate glucose-induced β-cell depolarization, which is required for triggering the voltage-dependent Ca2+ uptake subserving insulin release. The theory is that metabolism of glucose (and other fuel molecules) increases intracellular ATP or possibly other metabolites that diffuse to the membrane and inhibit the opening of ATP-sensitive K+ channels. This slows the efflux of positively charged K+ and depolarizes the cell. A recurrent source of confusion regarding this idea stems from the early observation that these channels are so exquisitely sensitive to intracellular ATP that channel opening is predicted to be ∼99% inhibited under physiological conditions. To account for this apparent discrepancy, various mechanisms have been proposed that might render the channels less sensitive to intracellular ATP. We use a simple mathematical model to demonstrate that there is no major discrepancy and that, in fact, given the electrophysiological mechanisms existing in the β-cell, the extreme sensitivity of the channels to ATP is appropriate and even mandatory for their physiological function.
Regulation of Whole-Body Leucine Metabolism With Insulin During Mixed-Meal Absorption in Normal and Diabetic Humans
Authors: Tessari Paolo , Pehling Gregory , Nissen Steven L , Gerich John E , Service F John , Rizza Robert A , Haymond Morey W
Published: September 2013

To determine the effects of insulin on dietary and endogenous leucine metabolism, five normal subjects, seven insulin-insufficient insulin-dependent (IDDM) diabetic patients, and five diabetic patients controlled with continuous subcutaneous insulin infusion (CSII) were studied before and for 8 h after ingestion of a chemically defined elemental test meal (10 cal/kg) containing crystalline amino acids. L-[1-14C]leucine was included in the meal to trace the entry and oxidation of the dietary leucine. Total (meal + endogenous) entry of leucine into the circulation was estimated with a constant infusion of [2H3]leucine. Postabsorptive and meal-related increases in the plasma leucine concentration were greater (P < .05) in the insulin-insufficient IDDM than in the normal subjects but returned to near-normal values with CSII. Baseline leucine flux was ∼40% greater in the insulin-insufficient IDDM than in normal subjects (2.17 ± 0.17 vs. 1.55 ± 0.15 μmol · kg−1 · min−1, respectively; .05 < P < .01) but were near normal during CSII treatment (1.85 ± 0.25 μmol · kg−1 · min−1). Furthermore, total leucine entry during meal absorption was greater in the insulin-insufficient IDDM (1.41 ± 0.10 mmol · kg−1.8 h−1) than in either normal (0.96 ± 0.08 mmol · kg−1 · 8 h−1, P < .01) or IDDM subjects during CSII treatment (1.09 ± 0.11 mmol · kg−1 · 8 h−1, P < .05). Fractional oxidation (∼40–50%) and entry of dietary leucine were similar in all three groups. The calculated rate of leucine entry from endogenous proteins over the 8 h of study in insulin-insufficient IDDM (1.04 ± 0.12 mmol · kg−1 · 8 h−1) was significantly greater than in normal subjects (0.64 ± 0.07 mmol · kg−1 · 8 h−, P < .01) or in IDDM subjects during CSII treatment (0.76 ± 0.10 mmol · kg−1 · 8 h−1, P < .05). However, during meal absorption, the calculated rate of leucine entry from endogenous protein was significantly suppressed below baseline only in the normal subjects. In summary, during absorption of a mixed meal, 1) one-third of the leucine entering the peripheral plasma space is derived from the diet in normal humans; 2) the rate of absorption and oxidation of dietary leucine in IDDM is normal regardless of adequacy of insulin therapy; and 3) postprandial hyperleucinemia in poorly controlled diabetic patients is at least partly the result of inadequate suppression of the entry rate of leucine from endogenous protein, suggesting persistence of excessive rates of proteolysis, which is at least partly corrected by intensified insulin treatment. Thus, insulin-mediated suppression of endogenous proteolysis is an integral part of protein anabolism during meal absorption.
Molecular Mechanisms in Basement Membrane Complications of Diabetes: Alterations in Heparin, Laminin, and Type IV Collagen Association
Authors: Tarsio Joseph F , Reger Lorrel A , Furcht Leo T
Published: September 2013

We report alterations in the ligand-binding properties of laminin, the major noncollagenous protein of basement membranes, resulting from nonenzymatic glycosylation in vitro. Mouse laminin was incubated in vitro with 500 mM glucose, and the level of nonenzymatically glycosylated amino acids increased 2-, 6.2-, and 12-fold after incubation for 1, 3, and 12 days, respectively. Ligand binding assays conducted in solution with varying concentrations of [3H]heparin and a constant amount of control or nonenzymatically glycosylated laminin showed a reduction in heparin binding proportional to laminin glycosylation. An analysis of the stoichiometry of [3H]heparin binding to control and nonenzymatically glycosylated laminin at saturating levels of heparin was performed. The results indicated that the total number of heparin binding sites on laminin decreased 4.7- and 14.7-fold due to nonenzymatic glycosylation of laminin for 1 and 3 days, respectively. [3H]heparin binding to 12-day nonenzymatically glycosylated laminin was abolished. Scatchard analyses of the binding data for heparin and laminin gave a dissociation constant (Kd) of 3.4 × 10−8 M. The data for nonenzymatic glycosylation of laminin for 1 day in vitro resulted in a biphasic heparin binding curve. Both high- and low-affinity binding was observed (Kd values of 3.3 × 10−8 and 2.6 × 10−7 M, respectively). Similar high- and low-affinity binding sites were seen on 3-day nonenzymatically glycosylated laminin (Kd values of 2.1 × 10−8 and 3.9 × 10−7 M, respectively). [3H]heparin binding at a fixed concentration to a constant amount of control or 12-day nonenzymatically glycosylated laminin and type IV collagen was also studied. Under control conditions, [3H]heparin binding to laminin was increased 3-fold in the presence of type IV collagen. The nonenzymatic glycosylation of laminin or type IV collagen substantially reduced type IV collagen–enhanced binding of heparin to laminin. The nonenzymatic glycosylation of both laminin and type IV collagen abolished type IV collagen–enhanced binding of heparin and reduced heparin binding to background levels. These observations are discussed in relation to the loss of heparan sulfate proteoglycan from the glomerular basement membrane in diabetes mellitus and in relation to the production of an initial lesion in the basement membranes of diabetic animals and humans.
Bacterial Phagocytosis and Intracellular Killing by Alveolar Macrophages in BB Rats
Authors: Sima Anders A F , O'Neill Shane J , Naimark David , Yagihashi Soroku , Klass Daniel
Published: September 2013

Diabetic patients and animals show an increased susceptibility to bacterial infections due to impaired bactericidal function of various host-defense mechanisms. In our study, we examined the ability of alveolar macrophages (AMs) of the diabetic BB rat to phagocytize and kill Staphylococcus aureus bacteria. Groups of spontaneously diabetic BB rats with variable severity of diabetes were used and compared with non-diabetes-prone BB rats. AMs obtained from diabetic insulin-deficient BB rats showed a markedly decreased capacity to phagocytize and kill bacteria, a defect that was partially corrected after a period of aggressive insulin treatment. Glucose-intolerant BB rats and diabetes-prone BB rats who did not develop diabetes showed a normal AM function compared to non-diabetes-prone BB rats. The impaired phagocytotic and bactericidal functions of AMs appeared to be caused by a cellular abnormality associated with the degree of insulin deficiency.
Glomerular Na+-K+-ATPase Activity in Acute and Chronic Diabetes and With Aldose Reductase Inhibition
Authors: Cohen Margo P , Klepser Henry
Published: September 2013

Sorbitol accumulation, myo-inositol depletion, and reduced Na+-K+-ATPase activity have been identified in experimental diabetes in several tissues in which diabetic complications occur. However, a reduction in renal Na+-K+-ATPase activity has not been universally reported, prompting us to examine the influence of diabetes duration on the activity of this enzyme complex in isolated glomeruli. Additionally, we examined the ability of the aldose reductase inhibitor sorbinil to directly stimulate glomerular Na+-K+-ATPase activity in vitro, an area of interest in view of the central position that the ability of sorbinil to restore Na+-K+-ATPase activity in vivo occupies in the interpretive scheme that links associated changes in sorbitol, myo-inositol, and Na+-K+-ATPase to enhanced polyol-pathway activity. Glomerular Na+-K+-ATPase activity was significantly decreased in rats with acute (< 18 days) streptozocin-induced diabetes but was significantly > control values in rats with more chronic (> 32 days) diabetes. In vitro addition of sorbinil (1 × 10−7 M) directly stimulated Na+-K+-ATPase in control (0.627 ± 0.090 vs. 0.843 ± 0.098 μmol Pi · mg−1 · min−1) but not diabetic glomeruli. These results indicate that the time of examination after induction of diabetes critically influences glomerular Na+-K+-ATPase activity and suggest that sorbinil, at least in normal glomerular tissue, has a membrane-associated effect that may be independent of its aldose reductase–inhibiting property.
Control of Glucose Phosphorylation and Glucose Usage in Clonal Insulinoma Cells
Authors: Shimizu Takao , Knowles Barbara B , Matschinsky Franz M
Published: September 2013

Glucose metabolism was investigated in two established clonal insulinoma cell lines (RINm5F and HIT) and in a newly developed line of mouse insulinoma cells (IgSV195). The hexokinase capacity in the homogenates of RINm5F cells was 22.1 ± 3.23 U/g protein, but glucokinase was barely detectable (0.06 ± 0.013 U/g protein). In contrast, both HIT and IgSV195 cells contained glucokinase (1.5 ± 0.17 and 1.0 ± 0.16 U/g protein, respectively) in addition to hexokinase activity. Glucose usage by the intact cells qualitatively reflected the glucose phosphorylation found in the cell-free extracts. RINm5F cells exhibited a high glucose usage rate with one high-affinity component, whereas both HIT and IgSV195 cells showed two components with different glucose affinities. HIT and IgSV195 cells may be useful for a model of pancreatic β-cell glycolysis.
Insulin Gene in Familial NIDDM: Lack of Linkage in Utah Mormon Pedigrees
Authors: Elbein Steven C , Corsetti Lynn , Goldgar David , Skolnick Mark , Permutt M Alan
Published: September 2013

Although non-insulin-dependent diabetes mellitus (NIDDM) is well recognized to be an inherited disease, the genetic lesion responsible remains to be determined. Several pedigrees have been reported in which defects of the insulin gene result in glucose intolerance or diabetes in affected members, but the role of insulin gene mutations in NIDDM is unknown. To evaluate this role, we ascertained 23 Caucasian pedigrees for a diabetic individual with at least one diabetic family member, sampled the unaffected individuals by a 75-g glucose tolerance test, and prepared leukocyte DNA on all family members. Included in the pedigrees ascertained were those with both predominantly lean and predominantly obese diabetic members and four pedigrees included as insulin-dependent diabetic individual. Insulin gene involvement was evaluated via previously described restriction-fragment-length polymorphisms (RFLPs) for the insulin gene and the nearby c-Ha-Ras oncogene (HRAS). Combination of these RFLPs resulted in the ability to trace the insulin alleles in all pedigrees studied. Analysis of individual pedigrees for sharing of insulin alleles was possible in 12 pedigrees, and lack of linkage was demonstrated in 6 of them. Neither linkage nor lack of linkage could be proved in the remaining pedigrees. Analysis of the pooled pedigree data failed to demonstrate linkage under several models, including autosomal-dominant and -recessive inheritance with different sporadic frequencies of diabetes and different prevalence figures. These results show that mutations of the insulin gene and the immediately surrounding area, including regulatory regions of the insulin gene, are unlikely to account for a significant subset of NIDDM in Caucasian individuals.
Severe Diabetes Induced in Subtotally Depancreatized Dogs by Sustained Hyperglycemia
Authors: Imamura Toshinori , Koffler Michael , Helderman J Harold , Prince Dale , Thirlby Richard , Inman Lindsey , Unger Roger H
Published: September 2013

Chronic clamping of plasma glucose levels at ≥250 mg/dl in four partially depancreatized but previously nondiabetic dogs was followed within 2 wk by persistent hyperglycemia and glycosuria of ≤500 g/day, ketonuria, and weight loss. Three of the four dogs required daily insulin injections to control these catabolic manifestations. There was no evidence of spontaneous improvement of the severe diabetic state during the 39–69 days of observation after discontinuation of intravenous glucose infusion. Impairment of intravenous glucose tolerance, loss of the insulin response to glucose and arginine, fasting hyperglucagonemia, exaggerated glucagon responsiveness to arginine, and a significant reduction in sensitivity to insulin were characteristic of all diabetic dogs. Morphometric analysis of the endocrine pancreas revealed a profound reduction in the number and size of identifiable islets of the hyperglycemic dogs compared with islets from their own pancreases resected months earlier and with those from pancreatic remnants of eight subtotally depancreatized control dogs that had not been subjected to chronic hyperglycemic clamping. The reduction in number and size of islets of the hyperglycemic dogs was largely the consequence of depletion of insulin-containing cells and was similar to that of dogs with long-standing alloxan-induced diabetes. In the eight control dogs, clinical evidence of diabetes did not develop during a follow-up period of 193–296 days. In this group, there was no evidence of diminution of intravenous glucose tolerance, of the insulin response to glucose or arginine, or of insulin sensitivity as determined by an acute hyperinsulinemic hyperglycemic clamp. The number and size of islets and number of β-cells in pancreatic remnants from these dogs did not differ morphometrically from those of the pancreatic segment that had been resected. We conclude that in subtotally depancreatized but nondiabetic dogs, maintenance of constant hyperglycemia of ≥ 250 mg/dl by means of intravenous glucose infusion causes a severe, persistent, and often insulin-requiring diabetic state that does not occur in the absence of the hyperglycemia.
Morphological Evidence for Pancreatic Polarity of β-Cell Within Islets of Langerhans
Authors: Bonner-Weir Susan
Published: September 2013

Reconstructions from serial paraffin sections were used to define the relationships of the pancreatic endocrine cells and the microvasculature of the islets of Langerhans of the rat. We have reported that the afferent vessel to an islet, an arteriole, enters the islet directly in the β-cell core. Immediately after entering the islet, this arteriole branches into capillaries. Herein, we report that β-cells have two capillary faces. When viewed in cross section, 8–10 β-cells form a tubelike structure around a central capillary. The outer side of each β-cell also abuts a capillary. A clear polarity of secretory granules was seen on the ultrastructural level when the β-cells were partially degranulated by prior in vivo treatment with glyburide. Of the remaining granules, 75.7 ± 1.7% were accumulated in the apical portion of the cell, even though this portion was only 50.4 ± 3.2% of the cytoplasm. β-Cells around a particular cross-sectioned capillary shared the same orientation of granular accumulation. These findings provide morphological evidence of in situ β-cell polarity that could be an anatomical basis for functional compartmentalization.
Adenine Nucleotide Metabolism in Hearts of Diabetic Rats: Comparison to Diaphragm, Liver, and Kidney
Authors: Jenkins Ronald L , McDaniel Huey G , Digerness Stanley , Parrish S Wayne , Ong Richard L
Published: September 2013

High-performance liquid chromatography analysis of acid-extracted tissues revealed decreases of high-energy nucleotides and increases in low-energy nucleotides and metabolites in heart, diaphragm, and liver but not in kidneys of diabetic rats. In comparison with nondiabetic rats, the total adenine nucleotide content of diabetic rat heart and diaphragm but not liver decreased, indicating an increase in catabolism of AMP. Maximal initial rates of the AMP catabolic enzymes 5′-nucleotidase, adenosine deaminase, and AMP deaminase were elevated in the hearts of BB/Wistar and streptozocin-induced diabetic rats. Nucleotide salvage enzymes adenylosuccinate synthetase and adenylosuccinate lyase were elevated above normal in the diabetic heart, whereas hypoxanthine-guanine phosphoribosyl transferase was not altered. Cytosolic-to-mitochondrial ratios from maximal initial rates after correction for mitochondrial breakage were increased above controls in diabetic hearts for nucleoside diphosphokinase and aspartate aminotransferase. Nucleotide levels, degradation rates, and substrate compartmentation between cytosol and mitochondria are discussed in relation to concurrent diabetes.
Reduction of Glycemic Potentiation: Sensitive Indicator of β-Cell Loss in Partially Pancreatectomized Dogs
Authors: Ward W Kenneth , Wallum Brad J , Beard James C , Taborsky Gerald J , Porte Daniel
Published: September 2013

To determine which test of islet function is the most sensitive indicator of subclinical β-cell loss, we studied six conscious dogs before and 1 and 6 wk after removal of the splenic and uncinate lobes [64 ± 2% pancreatectomy (PX)]. To assess hyperglycemic potentiation, acute insulin secretory responses (AIR) to 5 g i.v. arginine were measured at the fasting plasma glucose (FPG) level after PG was clamped at ∼250 mg/dl and after PG was clamped at a maximally potentiating level of 550–650 mg/dl. FPG levels were unaffected by PX (112 ± 4 mg/dl pre-PX vs. 115 ± 5 mg/dl 6 wk after PX, P NS). Similarly, basal insulin levels remained constant after PX (11 ± 2 μU/ml pre-PX vs. 11 ± 1 μU/ml 6 wk after PX, P NS). The AIR to 300 mg/kg i.v. glucose decreased slightly from 42 ± 9 μU/ml pre-PX to 32 ± 5 μU/ml 6 wk after PX (P NS), and thus the β-cell loss was underestimated. In contrast, insulin responses to arginine declined markedly after PX. The AIR to arginine obtained at FPG levels declined from 23 ± 3 μU/ml pre-PX to 13 ± 2 μU/ml 6 wk after PX (P = .04). The AIR to arginine obtained at PG levels of ∼250 mg/dl declined even more, from a pre-PX value of 56 ± 7 μU/ml to 21 ± 4 μU/ml 6 wk after PX (P = .02). However, the largest decline in AIR to arginine occurred at PG levels of 550–650 mg/dl (113 ± 13 μU/ml pre-PX vs. 28 ± 7 μU/ml 6 wk after PX, P = .001), thus indicating a marked decrease of maximal glycemic potentiation. Basal levels of glucose and insulin and AIRs to glucose and arginine obtained 1 wk after PX were similar to those obtained 6 wk after PX. The second purpose of the study was to explore mechanisms by which compensation of this β-cell loss occurs and by which hyperglycemia is avoided. One possibility is a reduction of glucagon secretion, but immunoreactive glucagon levels and glucagon secretory responses to arginine measured at three PG levels remained unchanged after PX. Similarly, tissue sensitivity to insulin, measured with euglycemic clamps at two elevated insulin levels, and insulin clearance remained unchanged after PX. Thus, the mechanism for maintenance of euglycemia after partial PX in the dog remains unclear. In summary, a reduction in glycemic potentiation of the insulin response to arginine was found to be the best means of detecting the subclinical β-cell loss induced by a two-thirds PX in dogs.
Role of Gluconeogenesis in Sustaining Glucose Production During Hypoglycemia Caused by Continuous Insulin Infusion in Conscious Dogs
Authors: Frizzell R Tyler , Hendrick Grant K , Biggers David W , Lacy D Brooks , Donahue D Patrick , Green Donald R , Carr R Keith , Williams Phillip E , Stevenson Ralph W , Cherrington Alan D
Published: September 2013

The roles of glycogenolysis and gluconeogenesis in sustaining glucose production during insulin-induced hypoglycemia were assessed in overnight-fasted conscious dogs. Insulin was infused intraportally for 3 h at 5 mU · kg−1 · min−1 in five animals, and glycogenolysis and gluconeogenesis were measured by using a combination of tracer [(3-3H]glucose and [U-14C]alanine) and hepatic arteriovenous difference techniques. In response to the elevated insulin level (263 ± 39 μU/ml), plasma glucose level fell (41 ± 3 mg/dl), and levels of the counterregulatory hormones glucagon, epinephrine, norepinephrine, and cortisol increased (91 ± 29 to 271 ± 55 pg/ml, 83 ± 26 to 2356 ± 632 pg/ml, 128 ± 31 to 596 ± 81 pg/ml, and 1.5 ± 0.4 to 11.1 ± 1.0 μg/dl, respectively; for all, P < .05). Glucose production fell initially and then doubled (3.1 ± 0.3 to 6.1 ± 0.5 mg · kg−1 · min−1; P < .05) by 60 min. Net hepatic gluconeogenic precursor uptake increased ∼ eightfold by the end of the hypoglycemic period. By the same time, the efficiency with which the liver converted the gluconeogenic precursors to glucose rose twofold. Five control experiments in which euglycemia was maintained by glucose infusion during insulin administration (5.0 mU · kg−1 · min−1) provided baseline data. Glycogenolysis accounted for 69–88% of glucose production during the 1st h of hypoglycemia, whereas gluconeogenesis accounted for 48–88% of glucose production during the 3rd h of hypoglycemia. These data suggest that gluconeogenesis is the key process for the normal counterregulatory response to prolonged and marked hypoglycemia.
Increased Hypothalamic Neuropeptide Y Concentrations in Diabetic Rat
Authors: Williams Gareth , Steel Jennifer H , Cardoso Helena , Ghatei Mohammad A , Lee Ying C , Gill Jaswinder S , Burrin Jacky M , Polak Julia M , Bloom Stephen R
Published: September 2013

Central and lateral hypothalamic concentrations of 10 regulatory peptides were measured by radioimmunoassay in streptozocin-induced diabetic (STZ-D) and matched control rats between 1 day and 14 wk after diabetes induction. After 2 wk, both central and lateral hypothalamic neuropeptide Y (NPY) concentrations in STZ-D rats were consistently higher than those found in control rats, with significant 30–50% increases at 4 wk in the central hypothalamus, and at 6 and 14 wk in both central and lateral hypothalamus. Immunocytochemical studies in 4- and 6-wk STZ-D animals showed the appearance of intensely NPY-positive swollen cell bodies in the supraoptic nucleus and a subjective increase in NPY staining of medial hypothalamic nerve fibers. Central hypothalamic concentrations of three other peptides were significantly greater in STZ-D animals than those in control animals at single points (neurotensin, 1 day; calcitonin gene-related peptide, 2 wk; neurokinin, 4 wk). Hypothalamic concentrations of the other six peptides examined (bombesin, galanin, neuromedin B, substance P, somatostatin, and vasoactive intestinal peptide) did not differ significantly between STZ-D and control groups at any time. However, galanin immunostaining in the supraoptic and magnocellular paraventricular nuclei was strikingly concentrated in a reduced number of distended cell bodies. Hypothalamic peptide changes in STZ-D could be related to metabolic disturbance, changes in energy and water balance, altered pituitary function, or other factors. Persistently elevated concentrations of NPY, a very potent central stimulant of eating and drinking, may mediate the hyperphagia and polydipsia characteristic of STZ-D.
Increased Superoxide Production by Mononuclear Cells of Patients With Hypertriglyceridemia and Diabetes
Authors: Hiramatsu Kazuko , Arimori Shigeru
Published: September 2013

Diabetic patients with hypertriglyceridemia frequently develop atherosclerosis. Because superoxide (O−2) is suspected to play an important role in the initiation of atherosclerosis, we investigated whether an abnormal amount of O−2 was produced by circulating mononuclear cells of patients with both diabetes mellitus and hypertriglyceridemia. The rate of production of superoxide dismutase–inhibitable O−2 was measured when cells were stimulated by either 4β-phorbol 12β-myristate 13α-acetate (PMA) or by opsonized zymosan (OZ). In addition, the rates of O−2 production by mononuclear cells drawn from three other groups (normal, solely diabetic, and solely hypertriglyceridemic) were determined. We found that the rate of O−2 production by mononuclear cells from the diabetic hypertriglyceridemic group was significantly higher than that from normal, diabetic, and hypertriglyceridemic groups. When the rates of O−2 production by mononuclear cells were plotted against the levels of plasma triglyceride for all individuals tested, they correlated positively (r = .73 in PMA stimulation and r = .79 in OZ stimulation, P < .01). However, the rate of O−2 production did not relate to other parameters, i.e., plasma cholesterol level, hemoglobin A1 level in erythrocytes, and the molar ratio of free cholesterol to phospholipid in mononuclear cells. Thus, we concluded that the observed elevated rate of O−2 production in the diabetic hypertriglyceridemic mononuclear cells was a reflection of a hypertriglyceridemic condition and was not unique to the diabetic hypertriglyceridemic condition. Also, O−2 may be involved in the pathogenesis of atherosclerosis in diabetic hypertriglyceridemic patients when atherogenic factors specific to diabetes are concomitantly present.