bluuebunny/crossref_metadata_2025 huggingface dataset:
Somatostatin Does Not Increase Insulin-Stimulated Glucose Uptake in Humans
Authors: Baron Alain D , Wallace Penny , Brechtel Ginger , Prager Rudolf
Published: September 2013

Somatostatin (SRIF) has been widely used in the study of in vivo carbohydrate metabolism to suppress pancreatic hormone secretion and thereby interrupt the glucoregulatory feedback loops between insulin, glucagon, and glucose. A critical assumption in the use of SRIF is that it has no effect on hepatic or peripheral glucose metabolism other than those mediated through the inhibition of hormone secretion. To assess whether doses of SRIF commonly used in human investigation have any effect on insulin-stimulated glucose disposal rates, we measured 5 ± the rate in 6 normal subjects (mean fasting serum glucose level, 93 ± 2 mg/dl) during euglycemic (≃85 mg/dl) hyperinsulinemic (40 mU · m−2 · min1) clamp studies both with and without the concomitant infusion of SRIF (600 μg/hr). The steady-state insulin levels achieved were 85 ± 6 μU/ml and 74 ± 8 (μU/ml with and without SRIF, respectively (difference not significant). Glucose disposal rates between 120 and 180 min of the clamp were 7.11 ± 0.10 and 7.35 ± 0.10 mg · kg1 · min1 with and without SRIF, respectively (difference not significant). We concluded that in doses commonly used in human investigation, SRIF does not increase glucose disposal.
Blood-Brain Barrier Choline Transport Is Reduced in Diabetic Rats
Authors: Mooradian Arshag D
Published: September 2013

The kinetics of blood-brain barrier (BBB) choline transport in streptozocin-induced diabetic rats were compared with those of age-matched vehicle-injected control rats. The brain uptake index (BUI) of choline in diabetic rats (13.9 ± 1.1%) was significantly lower than that in control rats (22.6 ± 0.7%) (P < .05). This alteration in brain choline uptake appeared to occur inlong-standing (9 wk) diabetes. Thus, acute hyperglycemia and diabetes mellitus for shorter periods (3 wk) did not significantly alter the BUI of choline. Insulin (8 U/kg) treatment for 5 days did not alter BUI in diabetic rats (12.9 ± 0.9%). The maximal velocity of BBB choline transport (Vmax) in diabetic rats (0.14 ± 0.07 nmol · min−1 · g−1) was significantly lower than the Vmax incontrol rats (2.2 ± 0.8 nmol · min−1 · g−1) (p < .05). The Km of choline transport in diabetic rats (120 ± 70 μM) was modestly but not significantly lower than that in control animals (400 ±160 μM). Similarly, the constant of the nonsaturable component of the transport (Kd) in diabetic animals (0.5 ± 0.07 μl · min−1 · g−1) was not significantly different from that in control rats (0.9 ± 0.3 μl · min−1 · g−1). The data indicate that diabetes mellitus in rats is associated with a decreased BBB choline transport.
Effects of Tolazamide and Exogenous Insulin on Pattern of Postprandial Carbohydrate Metabolism in Patients With Non-Insulin-Dependent Diabetes Mellitus: Results of Randomized Crossover Trial
Authors: Firth Richard , Bell Patrick , Marsh Michael , Rizza Robert A
Published: September 2013

To determine whether therapy with exogenous insulin or sulfonylureas results in a postprandial pattern of carbohydrate metabolism in patients with non-insulin-dependent diabetes mellitus (NIDDM) that resembles that in nondiabetic individuals, we employed a dual-isotope technique combined with forearm catheterization to examine meal disposition in NIDDM patients, before and after 3 mo of therapy with tolazamide and after 3 mo of therapy with exogenous insulin, with a randomized crossover design. Results were compared with those observed in nondiabetic subjects. Although both forms of therapy improved chronic glycemic control (glycosylated hemoglobin concentration went from 9.6 ± 0.7 to 7.6 ± 0.5 and 7.1 ± 0.2%, respectively, P <.01), exogenous insulin resulted in a lower postprandial glycemic response than tolazamide (P <.001). Both agents comparably increased (P <.01) fasting and integrated postprandial insulin concentrations. However, the initial rate of postprandial increase was greater with exogenous insulin (P <.05). Tolazamide (P <.05) but not exogenous insulin increased postprandial C-peptide concentrations. However, tolazamide did not improve the deficient early insulin release. Both agents (P <.05) lowered postabsorptive hepatic glucose release (from 2.8 ± 0.3 to 2.3 ± 0.2 mg · kg−1 · min−1), but not to normal rates (1.8 ± 0.1 mg · kg−1 · min−1). Endogenous glucose release after carbohydrate ingestion was lowered (P <.001) by insulin (from 633 ± 52 to 460 ± 41 mg kg−1 7 h−1) but not by tolazamide (625 ± 62 mg · kg−1 · 7 h−1) to rates observed in nondiabetic subjects (470 ± 32 mg · kg−1 · 7 h−1). Unmetabolized meal glucose reaching the systemic circulation did not differ before or after therapy with either insulin or tolazamide. Total postprandial glucose uptake was not changed by tolazamide (1308 ± 85 mg kg−1 · 7 h−1) but was lowered (P <.01) by exogenous insulin (from 1269 ± 57 to 1088 ± 67 mg · kg−1 · 7 h−1) to normal rates (1023 ± 64 mg kg−1 7 h−1). Forearm glucose uptakedid not differ among any group. We conclude that, although tolazamide and exogenous insulin, as administered in this study, both improve carbohydrate tolerance, therapy with exogenous insulin results in a pattern of postprandial carbohydrate metabolism that more closely approximates that observed in nondiabetic subjects.
Diminished Flare Response in Neuropathic Diabetic Patients: Comparison of Effects of Substance P, Histamine, and Capsaicin
Authors: Aronin Neil , Leeman Susan E , Clements Rex S
Published: September 2013

The flare response in skin largely depends on an intact primary sensory fiber, the C-fiber. We measured the flare response to the intradermal injection of substance P, histamine, and capsaicin in control subjects and in diabetic patients with and without clinically obvious polyneuropathy. The neuropathic diabetic patients had a reduced flare response to substance P, histamine, and capsaicin, compared with control and nonneuropathic diabetic subjects. The smaller flareresponse in the neuropathic diabetics after capsaicin administration suggested a dysfunction of the peripheral component of the C-fiber. Alternatively, dysfunction of the mast cell or vascular reactivity may contribute to the diminished flare. Because C-fibers participate in nociception in addition to the flare response, the findings of this study, by a method that permits a quantifiable measurement of the function of peripheral sensory neurons in diabetic subjects, has potential usefulness in evaluating sensory neuropathy in diabetic patients.
Effects of Glucose and Diabetes on Binding of Naloxone and Dihydromorphine to Opiate Receptors in Mouse Brain
Authors: Brase David A , Han Yi-Hong , Dewey William L
Published: September 2013

The effects of glucose and diabetes on the high-affinity lofentanil-displaceable opiate-receptor binding in mouse brain membranes were studied to determine if the attenuation of opiate actions by hyperglycemia previously observed in our laboratory was due to a modification of receptor affinity or number. With embranes from normal ICR mice, glucose (100–400 mg/dl) caused small but significant concentrationdependent decreases in receptor affinities for [3H]naloxone and [3H]dihydromorphine, both in the absence and presence of 20 mM NaCI, without changing the maximum number of binding sites. Fructose and the nonmetabolizable sugar 3-O-methylglucose had intermedi ate effects on naloxone affinity in the presence of NaCI that were not significantly different from control or from the effect of glucose. Similar results were obtained with brain membranes from streptozocin-induced diabetic mice. The binding affinity for [3H]naloxone in the presence of NaCI was not affected by the induction of diabetes in ICR mice via streptozocin or in spontaneously diabetic (db/db) C57BL/KsJ mice compared with their nondiabetic (m+/m+) litter mates. These results indicate that the previously observed attenuation of opiate effects by glucose may be partly due to a glucose-induced decrease in opiate-receptor affinity. However, the much greater attenuation of morphine by fructose in vivo cannot be explained by this mechanism.
Quantitative Assay for Human Cytoplasmic Islet Cell Antibodies
Authors: Bright George M
Published: September 2013

An assay for human islet cell antibodies (ICAs) in serum yielding numerical values and amenable to statistical evaluation has been developed utilizing fluorescence spectrophotomicroscopy (FSPM). The results of the blinded trials by FSPM were compared with those by standard indirect immunofluorescence (IFL). No false-positive or false-negative readings were obtained in 258 observations when the results by FSPM were compared with those by IFL. The intraand interassay variabilities encountered were not enough to misclassify a specimen. The presence of anti-thyroid, anti-adrenal, or anti-nuclear antibodies did not produce false-positive readings. Twenty-eight additional specimens from diabetic children were also analyzed via three blood group type O pancreases. There was complete agreement concerning the presence or absence of ICA between IFL and FSPM analyses. Analysis of the three pancreases yielded different numbers of results positive for ICA (14/28 vs. 22/28 vs. 15/28, P = .008) in both assays. Thus, selection of pancreatic substrate may influence the outcome of assays for ICA. A matrix of fluorescent microspheres has been devised that allows calibration of the FSPM system. Now, reproducible and comparable readings for ICA values can be obtained from the various reporting laboratories. Should an international reference serum for ICA become available, the remaining problem in the ICA assay, that of substrate (pancreas) variability, should be resolved.
Regulation of Lipoprotein Lipase by Glucose in Primary Cultures of Isolated Human Adipocytes: Relevance to Hypertriglyceridemia of Diabetes
Authors: Kern Philip A , Mandic Angela , Eckel Robert H
Published: September 2013

Human adipose tissue lipoprotein lipase (LPL) is stimulated in vivo by an insulin-glucose infusion. However, previous work by us showed no effect of physiologic insulin concentrations on LPL in isolated human adipocytes. To pursue further the regulation of LPL in vitro, primary cultures of isolated human adipocytes were prepared and exposed to glucose concentrations of 0–4.5 mg/ml. LPL activity was measured as activity secreted into the culture medium (CM), released from cells by heparin (HR), and extracted from cell digests (EXT). After 5 h in culture, a stimulatory effect of glucose on HR was observed. After 24 h there was a gradual increase in CM, HR, and EXT in parallel with increasing glucose concentrations of 0—1.0 mg/ml. At glucose concentrations >1.0 mg/ml, however, there was a decrease in CM. At a glucose concentration of 4.5 mg/ml, CM was only 51 ± 14% (P < .02) of its value at glucose concentrations of 1.0 mg/ml. Cellular LPL (HR and EXT) was not affected by high glucose concentrations. Response of cellular LPL to the hormonal regulator insulin-like growth factor I (IGF-I) was modulated by medium glucose. HR in cultures treated with 50 ng/ml IGF-I was 166 ± 40 and 147 ± 23% of HR in control cultures at glucose concentrations of 1.0 and 2.5 mg/ml, respectively (P ≤.05). However, IGF-I failed to stimulate HR at glucose concentrations >2.5 mg/ml or <1.0 mg/ml. Adipocyte protein synthetic rate was not inhibited by medium containing 4.5 mg/ml glucose, suggesting that these high glucose concentrations were not generally toxic to cells. The hexoses galactose, L-glucose, and 3-Omethylglucose had no effect on LPL, but pyruvate and D-glucose stimulated HR. Cellular ATP was relatively constant regardless of medium conditions and bore no relationship to LPL. Thus, glucose plays an important role in the regulation of LPL in isolated human adipocytes. In addition, the decrease in CM and the blunted response of HR to IGF-I in high glucose suggest that hyperglycemia per se may contribute to the decreased LPL and consequenthypertriglyceridemia of poorly controlled diabetes.
Accelerated Glomerulosclerosis in Diabetic Rats With Immune Complex Injury
Authors: Abrass Christine K , Cohen Arthur H
Published: September 2013

Immune complex-mediated injury has been postulated to contribute to diabetic microangiopathy. To test this hypothesis, immune complex disease was induced in both insulin-deficient (I−) and insulin-treated (I+) rats with streptozocin-induced diabetes mellitus (DM), and the rats were compared with their respective controls. Heymann nephritis (HN), an animal model of membranous nephropathy, was induced in rats by immunization with proximal renal tubular brush border antigen. In addition to the homogeneous mesangialdeposits of IgG that developed in diabetic rats, diabetic rats with immune injury also developed immune deposits of IgG and tubular antigen. Diabetic animals with Heymann nephritis developed more intense granular mesangial and capillary wall immune deposits, detected by immunofluorescence (ranked-sums test, P = .002) and electron microscopy. Mesangial immune deposits were associated with mesangial hypercellularity, determined by counting nucleli per glomerular cross section. Diabetic animals with immune injury had an increased number of nucleI− (DM, I− , HN: 70 ± 4; DM, I+, HN: 65 ± 3) compared with animals with only Heymann nephritis (55 ± 4) or only diabetes [DM, I−: 52 ± 4; DM, I+: 54 ± 3 (mean ± SE); P < .05, ANOVA]. An increase in the accumulation of mesangial matrix in diabetic animals with Heymann nephritis was also apparent by light microscopy and immunofluorescence staining of the mesangium for fibronectin. Insulin treatment and control of hyperglycemia did not prevent the development of these changes. Animals with only Heymann nephritis had lesser amounts of immune deposits, which were limited to the subepithelial space and not associated with structural alterations of the mesangium. Increased mesangial sclerosis associated with immune injury in diabetic rats was accompanied by a fall in creatinine clearance (DM, I− , HN: 0.3 ± 0.1 ml · min−1 · 100 g−1 body wt; DM, I+, HN: 0.3 ± 0.1) compared with the elevated filtration rates that usually occur in diabetic animals [DM, I−: 0.7 ± 0.2; DM, I−: 0.7 ± 0.1 (mean ± SD); P < .05, ANOVA]. Animals with both diabetes and Heymann nephritis had increased mortality (DM, I− , HN: 50%; DM, I+, HN: 88%) compared with all other experimental groups (range 0–13%; x2- analysis, P < .05). This study suggests that immune complex-mediated injury can lead to accelerated mesangial sclerosis in rats with streptozocin-induced diabetes.
Cross-Reactivity of Organs in Allograft Rejection: Comparison of Effect of Thyroid Allografts on Established Islet Allografts
Authors: Kover Karen , Hegre Orion , Popiela Heinz , Biggs Thomas , Moore Wayne V
Published: September 2013

The effect of allotransplantation of thyroid or islet allografts into rats with established islet allografts was studied to determine the cross-reactivity of the thyroid and islets in allograft rejection. Islets obtained from cultured neonatal rat (F344) pancreas explants were transplanted bilaterally underneath the kidney capsule of Wistar-Furth rats. After 21 days these allografts did not exhibit signs of rejection. Thyroid (half lobe) from either F344 or Brown Norway rats was transplanted underneath the capsule of the remaining kidney. Transplant of the thyroid from F344 rats resulted in immediate rejection of the islet transplant, whereas transplant of the thyroid from Brown Norway rats was without effect on the islet allograft. This indicates that the thyroid contains immunocompetent cells (cells that present antigen or induce recognition of antigen) that are capable of initiating rejection of established islet allografts. The cytotoxic T-lymphocytes that result are specific for the organ bearing the immunocompetent cells at time of transplantation.
Continuous Subtherapeutic Insulin Counteracts Hypothalamopituitary-Gonadal Alterations in Diabetic Rats
Authors: Bestetti Gilberto E , Junker Ursula , Locatelli Vittorio , Rossi Giovanni L
Published: September 2013

In experimental animal models, gonadal axis lesions are probably responsible for reproductive disorders associated with diabetes mellitus. The pathogenesis of these disorders is not yet known, but it is assumed that insulin deficiency plays an important role. To check this hypothesis, we have investigated the hypothalamopituitary-gonadal axis of insulin-treated streptozocin-induced diabetic (STZ-D) rats and compared it with that of untreated diabetic and control animals. Insulin was delivered by subcutaneously implanted osmotic minipumps. Furthermore, to determine whether possible beneficial insulin effects are selectively limited to the gonadal axis or act generally, we also studied retinal microangiopathy. The hypothalamopituitary-gonadal axis of insulin-treated diabetic animals was almost unchanged. On the contrary, retinal microangiopathy was only slightly influenced by subtherapeutic insulin doses. In conclusion, continuous administration of insulin at subtherapeutic doses can successfully counteract most of the effects of diabetes on the gonadal axis. Thus, the gonadal-axis impairment in STZ-D animals appears to be related to the fall of plasma insulin below a critical level. Furthermore, the various organ systems may respond to different plasma insulin threshold levels.
Impaired Cytokine Response in Male ICR Swiss Mice After Infection With D Variant of Encephalomyocarditis Virus
Authors: Bigley Nancy J , Blay Roy A , Smith Randall A
Published: September 2013

The basis for the resistance of the female and the susceptibility of the male ICR Swiss mouse to the diabetogenicity of the D variant of encephalomyocarditis virus (EMCV-D) is unknown. This pattern of disease resistance and susceptibility can be reversed if females are treated with testosterone and males are treated with estrogen before virus infection. As a possible explanation for this sex difference in disease development, differences in early antiviral host responses were explored. Cellular antiviral resistance mechanisms operative early in virus infection were evaluated in ICR Swiss mice of both sexes after intraperitoneal infection with virus. No differences were seen in splenic natural killer (NK) cell responses of male and female mice during the 1st wk of infection, during which only the males became diabetic. Depletion of NK cell activity with rabbit anti-asialo GM1 serum did not render the infected ICR Swiss female susceptible to virus-induced diabetes. Treatment of ICR Swiss mice with type I carrageenan to compromise macrophage function rendered the female susceptible to diabetes after infection with EMCV-D but made only the male susceptible to diabetes by the usually avirulent interferon-inducing EMCV-B. Concanavalin A and recombinant interleukin 2, inducers of immune interferon, which in turn primes macrophages for activation and induces their expression of la antigens, protected the ICR Swiss male against the diabetogenic effects of EMCV-D. Interleukin 2 enhanced the male's capacity to exhibit an increase in the expression of la antigen by peritoneal exudate cells 1 day after infection with EMCV-D to a level seen in disease-resistant females. These results suggest that the more responsive macrophage system of the female is important in the innate resistance of the ICR Swiss female to virus-induced diabetes and, conversely, the less responsive macrophage system of the male contributes to his susceptibility to diabetes induction by EMCV-D and by EMCV-B after impairment of macrophage function.
Starvation-Related Alterations in Free Radical Tissue Defense Mechanisms in Rats
Authors: Wohaieb Saleh A , Godin David V
Published: September 2013

Alterations in endogenous free radical-scavenging defense mechanisms of rat tissues after body weight loss (induced by starvation for 72 h) associated with hypoinsulinemia were investigated. The activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione (GSSG) reductase as well as levels of reduced glutathione (GSH) were examined in several tissues and in erythrocytes. A complex pattern of changes was observed. CAT activities were increased in the heart and pancreas and decreased in the liver. SOD levels were decreased in the heart and increased in the kidney and pancreas. GSH-PX activities were increased only in the kidney, and levels of GSH were decreased only in the liver of starved animals. Erythrocytes from starved animals showed no alterations in the levels of major free radical-scavenging enzymes. However, GSSG reductase levels were lower in erythrocytes from starved animals, and this was associated with an increased susceptibility to H2O2-induced GSH depletion. Paradoxically, H2O2-induced malondialdehyde (MDA) production in erythrocytes from starved animals was lower than that in control erythrocytes. Our results suggest that, in studies of experimental diabetes, attention must be given to the influence of body weight loss per se on the biochemical alterations associated with this disease.
Insulin and Glyburide Increase Cytosolic Free-Ca2+ Concentration in Isolated Rat Adipocytes
Authors: Draznin Boris , Kao Marilee , Sussman Karl E
Published: September 2013

We investigated the effect of insulin and a hypoglycemic sulfonylurea agent glyburide on cytosolic free-Ca2+ concentrations ([Ca2+]i) in isolated ratadipocytes. Both insulin and glyburide increased [Ca2+]i in a dosedependent manner. Half-maximal effects were seen at 0.5 ng/ml of insulin and 0.5 μM glyburide. Nifedipine (25 μM), a Ca2+-channel blocker, inhibited the effectof both agents. The effect of insulin on [Ca2+]i was 40 and 70% potentiated by ambient glucose concentrations at 180 and 300 mg/dl, respectively. Depolarizingdoses of potassium (40 mM) induced an increase in cytosolic Ca2+ that was also inhibited by nifedipine. It is suggested that both insulin and glyburide increase cytosolic free Ca2+ levels at least in part by promoting Ca2+ influx through voltage-dependent Ca2+ channels.
Initial Phase II Clinical Studies on Midaglizole (DG-5128): A New Hypoglycemic Agent
Authors: Kawazu S , Suzuki M , Negishi K , Ishii J , Sando H , Katagiri H , Kanazawa Y , Yamanouchi S , Akanuma Y , Kajinuma H , Suzuki K , Watanabe K , Itoh T , Kobayashi T , Kosaka K
Published: September 2013

Midaglizole (DG-5128), 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-phenylethyl]pyridine dihydrochloride sesquihydrate, is a new type of oral antidiabetic agent that has an α2-adrenoceptor-antagonizing effect. As previously reported, midaglizole reduces plasma glucose, mainly by stimulation of insulin secretion, and inhibits epinephrine-induced platelet aggregation in normal human subjects.

In this study, the clinical safety and efficacy of shortterm administration of midaglizole were evaluated in 47 patients with non-insulin-dependent diabetes mellitus (NIDDM). After an observation period on diet or sulfonylurea treatment (1 patient was on insulin), patients received 150–250 mg 3 times a day of midaglizole for 2–4 wk, (some patients continued treatment for >4 wk).

In 20 of the patients first treated with diet and then switched to midaglizole treatment, fasting plasma glucose (FPG) decreased significantly from 187 ± 10 mg/ dl (mean ± SE) to 147 ± 13 mg/dl (P < .05) and 120 ± 6 mg/dl (P < .01) 2 and 4 wk, respectively, after administration of midaglizole. Glycosylated hemoglobin (HbA1 also decreased from 12.0 ± 0.7 to 11.3 ± 1.1 and 10.7 ± 0.6% after 2 and 4 wk, respectively. In 23 of the patients whose treatment was changed from sulfonylureas to midaglizole, FPG, and HbA1 levels were maintained at the same values obtained before administration of midaglizole. In patients treated with midaglizole for >12 wk, FPG and HbA1 were kept at the lowered levels.

Moreover, midaglizole treatment showed a clear inhibitory effect on postprandial hyperglycemia and onFPG, reflecting the general improvement in the daily plasma glucose curve with significantly reduced fluctuation. In the oral glucose tolerance test, midaglizole significantly improved glucose tolerance, potentiated insulin secretion, and tended to depress glucagon secretion.

No abnormal findings attributable to midaglizole were noted in clinical and laboratory examinations, except for diarrhea and soft stools in 4 cases (8.5%) out of 47. No hypoglycemic symptoms were observed in this trial.

Thus, midaglizole is clinically effective for NIDDM because it improves the daily plasma gluocse curve, with decreased fasting and postprandial hyperglycemia, in addition to amelioration of oral glucose tolerance accompanied by accelerated insulin secretion.
Insulin Action in Obese Non-Insulin-Dependent Diabetics and in Their Isolated Adipocytes Before and After Weight Loss
Authors: Zawadzki Joanna K , Bogardus Clifton , Foley James E
Published: September 2013

To determine the effects of weight loss on insulin action in patients with non-insulin-dependent diabetes mellitus (NIDDM) and in their isolated adipocytes, we studied nine weight-stabilized Pima Indians [7 females and 2 males; age 39 ± 3 yr; wt 99.9 ± 8.2 kg; body fat 39 ± 2% (means ± SE)] before and after a 6.7 ± 1.3-kg weightloss and decrease in fasting plasma glucose from 250 ± 11 to 148 ± 15 mg/dl. Invivo insulin action was measured during a 3-insulin-step, hyperglycemic (∼310 mg/dl) clamp with somatostatin (250 μ/h). At a clamp plasma insulin concentration of ∼10 μU/ml, glucose disposal rates did not change after weight loss; at ∼100 μU/ml, glucose disposal rates increased by 21% [from 4.3 ± 0.2 to 5.3 ± 0.4 mg · min−1 · kg−1 of fat-free mass (FFM), P < .01] mostly due to increased carbohydrate oxidation rates (2.0 ± 0.3 to 2.8 ± 0.3 mg min−1 kg−1 FFM, P < .02); at ∼2400 μU/ml, glucose disposal rates increased by 37% (11.4 ± 0.6 to 15.6 ± 1.4 mg min−1 kg−1 FFM, P < .02) mostly due to increased nonoxidative carbohydrate disposal rates or storage (7.5 ± 0.6 to 10.9 ± 1.3 mg min−1 kg−1 FFM, P < .04). Sensitivity of glucose disposal to insulin in the physiologic range (measured as change in glucose disposal rate per unit change in insulin concentration between clamps at ∼10 and ∼100μU/ml) was very low in these diabetic subjects and did not change after weight loss. Adipocyte cell size, basal and maximal insulin-stimulated glucose transport, and half-miximal rate for transport did not change after weight loss. The data suggest that insulin in the physiologic range has no apparent effect on glucose disposal in patients with NIDDM before or after weight loss. However, a moderate weight loss isassociated with enhanced capacity to transport and metabolizeglucose in vivo. The discrepancy between in vivo and in vitro results suggests that the adipocytemay not always reflect in vivo insulin action.
Evidence for Existence of Polyol Pathway in Cultured Rat Mesangial Cells
Authors: Kikkawa Ryuichi , Umemura Kisaburo , Haneda Masakazu , Arimura Tetsuro , Ebata Kazuhiko , Shigeta Yukio
Published: September 2013

The accumulation of polyols has been previously found in renal glomeruli isolated from streptozocin-induced diabetic (STZ-D) rats, although the intraglomerular polyol pathway has not been exactly localized. Because we have previously observed mesangial cell dysfunction in STZ-D rats, we examined whether the polyol pathway exists in mesangial cells as a possible candidate of the cause of cellular dysfunction. The activities of two polyol pathway enzymes, aldose reductase and sorbitol dehydrogenase, were clearly detected in the crude homogenate of cultured mesangial cells at higher levels than those of whole glomeruli when DL-glyceraldehyde or D-fructose was used as substrate. When cells were incubated in medium containing 55 mM glucose or galactose, a large amount of sorbitol or galactitol was accumulated intracellularly. The accumulation of polyolswas effectively blocked by an aldose reductase inhibitor, ICI 128436. These results suggest that the polyol pathway exists in mesangial cells of rat glomeruli and may play a role in the development of mesangial cell dysfunction found in STZ-D rats.
Hormone Release From Pancreatic Islets Perfused from Venous Side
Authors: Kawai Koichi , Chiba Yukinobu , Okuda Yukichi , Yamashita Kamejiro
Published: September 2013

Directional blood flow in panreatic islets may be important for regulation of islet hormone release. We therefore perfused an isolated canine pancreas via the celiac artery (arterial perfusion) and then via the portal vein (venous perfusion) in the same pancreas. Basal insulin and glucagon levels and their rate of release in response to 10 mM arginine, 11 mM glucose, 500 pg/ml somatostatin, or 500 pg/ml glucagon were similar under both conditions. However, the inhibition of glucagon release due to somatostatin and its recovery after the cessation of somatostatin infusion was poor in the case of venous perfusion. The basal somatostatin level and its release in response to 10 mM arginine, 11 mM glucose, and 500 pg/ml glucagon during venous perfusion was significantly higher than that during arterial perfusion. From these results, it is speculated that the directional blood flow in pancreatic islets may not be essential for regulation of hormone release from the canine pancreas or that such directionality does not exist in canine pancreatic islets, and that a considerable portion of released somatostatin may be taken up by the pancreas located downstream—probably in the exocrine pancreas.
Seasonality in Glycosylated Hemoglobin in Normal Subjects: Does Seasonal Incidence in Insulin-Dependent Diabetes Suggest Specific Etiology?
Authors: MacDonald Michael J , Liston Leone , Carlson Ian
Published: September 2013

Seasonality in the diagnosis of insulin-dependent diabetes mellitus (IDDM), i.e., increased incidence in winter, was the impetus for this study of seasonality in glycosylated hemoglobin levels in nondiabetics. Glycosylated hemoglobin levels of 35 nondiabetic children and adults were highest at the ends of autumn and winter and lowest at the ends of spring and summer (P < 10−4). This result is consistent with reports of seasonal variation in blood glucose, with the highest levels occurring in winter, as well as reports that suggest an internal milieu of increased counterinsulin action in winter due to seasonality in counterinsulin hormones, dietary factors, body weight, amount of exercise, growth rates in children, and ambient temperature. IDDM is caused by the gradual destruction of the pancreatic insulin-producing cells via lymphocytic infiltration—a process that may occur over years. We conclude that a decreased carbohydrate tolerance associated with winter can explain the seasonal variation in the incidence of IDDM and that this seasonality is caused by the precipitation of overt carbohydrate intolerance in individuals with already seriously compromised insulin secretory capacity. This implies that seasonality is not very informative about the cause of the destruction of pancreatic insulin-producing cells.
Failure of Genetically Selected Miniature Swine to Model NIDDM
Authors: Hand Michael S , Surwit Richard S , Rodin Judith , Van Order Paula , Feinglos Mark N
Published: September 2013

Ten young adult miniature swine from a line reported to be genetically selected for glucose intolerance and eight normal controls were obtained from Colorado State University. They were consecutively exposed to 4 mo of a high-fiber, low-fat standard swine diet; 4 mo of a high-sucrose, high-fat, low-fiber diabetogenic diet; and 4 mo of excess diabetogenic diet for obesification. Results of oral glucose tolerance and intravenous insulin tolerance tests conducted at the end of each regimen were compared. Hyperglycemia was not observed in any animals after any manipulation. Insulin sensitivity was also not influenced by diet. We conclude that F7 low-K miniature swine from this colony fail to model human non-insulin-dependent diabetes.
Glucose Counterregulation in Pre-School-Age Diabetic Children With Recurrent Hypoglycemia During Conventional Treatment
Authors: Brambilla P , Bougneres P F , Santiago J V , Chaussain J L , Pouplard A , Castano L
Published: September 2013

To determine whether immature or defective glucose counterregulation was responsible for the severe recurrent hypoglycemic episodes (3.6 per patient per year) observed during conventional therapy (CT) in six pre-school-age diabetic children, we investigated their metabolic and hormonal responses to insulin infusion (40 mU/kg i.v. for 60 min). Counterregulation was considered adequate because no patient experienced symptoms requiring discontinuation of the test, and blood glucose (BG) nadirs averaged 42 ± 5 mg/dl. Glucose production rate decreased from 4.2 ± 0.2 to 2.6 ± 0.6 mg · kg−1 · min−1. Blood 3-hydroxybutyrate levels were elevated (∼ 3 mM) and did not change during insulin infusion. The responses of epinephrine (from 137 ± 37 to 393 ± 143 pg/ml), norepinephrine (from 145 ± 33 to 347 ± 152 pg/ml), and growth hormone (from 6.0 ± 1.5 to 20.3 ± 5.1 ng/ml) were normal for this age group. As previously observed in diabetic adults, glucagon response was deficient (from117 ± 30 to 114 ± 18 pg/ml). The six children were subsequently treated with continuous subcutaneous insulin infusion (CSII), which resulted in a 20-fold decrease in the number of severe hypoglycemic reactions. Predisposition to severe hypoglycemia in this subset of diabetic children, which remains a refractory problem even after considerable efforts have been made to decrease them, may thus be sharply decreased with CSII therapy. During this therapy, a significant inverse correlation appeared between the individual frequency of BG values <40 mg/dl and BG nadir during the insulin infusion test (r = .94, P < .001). We conclude that the glucose counterregulatory status evaluated by a simple standardized insulin- infusion test can predict the risk of developing hypoglycemia during CSII in young diabetic children, as proposed previously in adults.
Allotransplantation of Islet Endocrine Aggregates
Authors: Kakizaki Kenji , Basadonna Giacomo , Merrell Ronald C
Published: September 2013

Dissociated pancreatic islets form endocrine aggregates from single-cell suspension by rotation culture. Islet cell aggregates, or neoislets, can provide endocrine reconstitution for diabetic rats and enjoy prolonged graft survival when neoislets are transplanted across a major histocompatibility barrier (Lewis to ACI). Long-term survival of grafted neoislets was obtained in 71% of recipients without any immunosuppression and in 100% of recipients with minimal immunosuppression. As predicted by cell-cell recognition in rotation-mediated aggregation, neoislets apparently exclude mesenchymal cells that bear la antigens. Therefore, reduced immunogenicity is accomplished.
Hyperinsulinemia Does Not Compensate for Peripheral Insulin Resistance in Obesity
Authors: Prager Rudolf , Wallace Penny , Olefsky Jerrold M
Published: September 2013

Based on previous steady-state measures of the biologic activity of insulin, it was thought that postprandial hyperinsulinemia in obesity compensated for insulin resistance. However, we recently demonstrated kinetic defects in insulin action in insulin-resistant nondiabetic obese subjects: activation of insulin-stimulated glucose disposal was slower and deactivation was faster in obese than in normal subjects. In view of these kinetic defects in peripheral insulin action and of the fact that insulin is normally secreted in a phasic manner after meals, we postulated that the hyperinsulinemia of obesity does not compensate for insulin resistance and that the abnormal kinetics of insulin action in obesity are functionally important. To test this hypothesis, oral glucose tolerance tests (OGTTs) were performed in five control (mean age, 33 ± 2 yr) and five obese (mean age, 41 ± 5 yr) subjects. All controls had normal glucose tolerance; two obese subjects had normal and three had impaired glucose tolerance. After the results of the OGTTs were available, euglycemic clamp studies were performed in which insulin was infused in a phasic stepped fashion to mimic the rise and fall of mean peripheral insulin levels during the OGTTs. Each subject was clamped at both the “normal” and “obese” OGTT insulin profiles.

During the OGTT, glucose and insulin levels were significantly elevated in the obese subjects compared with controls. Insulin-stimulated glucose disposal rates and total incremental glucose disposal (IGD) over 4 h were markedly reduced in obese compared with control subjects at the lower (normal) insulin-infusion profile (3 ± 1 vs. 41 ± 5 g, P < .001) and at the higher (obese) insulin-infusion profile (15 ± 4 vs. 72 ± 6 g, P < .001). Furthermore, during the normal insulin profile in controls compared with the obese insulin profile in obese subjects, IGD was still significantly reduced in the obese subjects (41 ± 5 vs. 15 ± 4 g, P < .001). At the lower as well as the higher insulin infusion, suppression of hepatic glucose output was not significantly different between obese and control subjects, as assessd by analysis of variance.

In conclusion, our data demonstrate three important points. 1) Kinetic defects in the onset and decay of peripheral insulin action are functionally important in obesity when insulin is infused to match the physiological rise and fall of OGTT insulin levels. 2) Postprandial hyperinsulinemia in obesity only partially compensates for the peripheral insulin resistance. 3) The relative postprandial hyperglycemia in obesity may promote glucose disposal via the mass action of glucose and may be an important compensatory factor serving to normalize peripheral glucose disposal in insulin-resistant obese subjects.
Interactions of Cholecystokinin and Glucose in Rat Pancreatic Islets
Authors: Zawalich Walter , Takuwa Noriko , Takuwa Yoh , Diaz Victoria A , Rasmussen Howard
Published: September 2013

The effects of sulfated cholecystokinin (CCK-8S) and glucose on insulin secretion and polyphosphoinositide (PPI) metabolism were studied in isolated rat islets. Both agonists stimulate PPI hydrolysis, inositol phosphate accumulation, 3H efflux from [3H]inositol-prelabeled tissue, and 45Ca efflux from prelabeled cells. However, the effects ofCCK-8S on PPI metabolism are considerably greater than those of glucose. Furthermore, the effectsof CCK-8S on PPI and Ca2+ metabolism are observed whether islets are incubated in either 2.75 or 7 mM glucose, but CCK-8S only stimulates insulin secretion (a biphasic response) when the higher glucose concentration is present. Addition of 1 μM forskolin to islets incubated in media containing 2.75 mM glucose does not influence basal insulin secretion but sensitizes the islets to the action of CCK-8S. In the presence of forskolin, CCK-8S induces a very marked first phase but no second phase of insulin secretion. We postulate that CCK-8S acts in this tissue via receptor-linked PPI hydrolysis, leading to an inositol trisphosphate-induced Ca2+ efflux. These receptor- mediated effects of CCK-8S are not altered either by the ambient glucose concentration or the cAMP content of the islets, but these two factors determine the responsiveness of the islets (in terms of insulin secretion) to a given CCK-8S signal.
Persistent Impairment of Insulin Secretory Response to Glucose in Adult Rats After Limited Period of Protein-Calorie Malnutrition Early in Life
Authors: Swenne Ingemar , Crace Caroline J , Milner R David G
Published: September 2013

The effect of a limited period of protein-calorie malnutrition in young rats on glucose tolerance, insulin secretory response to glucose, and tissue composition in the adult was studied. Three-week-old rats were weaned onto semisynthetic diets containing either 5% protein (low protein; LP) or 15% protein (control; C) and maintained for 3 wk on their respective diets. At 6 wk of age all rats were returned to a commercial rat chow diet (18% protein). Glucose tolerance, insulin secretory response to glucose, and the protein/DNA ratio in liver, skeletal muscle, heart, kidney, small intestine, and lung were investigated at 3, 6, and 12 wk of age. Rats receiving LP diet failed to gain weight, but growth resumed immediately when they were transferred to commercial rat chow. They did not, however, catch up with C rats. Glucose tolerance and insulin secretory response to glucose remained similar between 3 and 12 wk in C rats. In 6-wk-old LP rats, glucose tolerance was impaired, and the insulin secretory response to glucose was absent. At 12 wk of age the glucose tolerance of the LP rats had normalized, but the insulin secretory response was still blunted. In 6-wk-old LP rats there was an inhibition of the age-dependent increase in cell size, shown by lowered protein/DNA ratios in all tissues studied. This decrease in cell size persisted at 12 wk in liver, skeletal muscle, heart, and lung.

We conclude that protein-calorie malnutrition early in life persistently impairs the insulin secretion. The persistently lowered protein/DNA ratios in many tissues may be related to this lowered capacity for insulin secretion. The individual could have an impaired ability to respond to diabetogenic and nutritional challenges, and it is thus possible that the early malnutrition may predispose for diabetes.
Somatomedin-C in Human Fetal Pancreas: Cellular Localization and Release During Organ Culture
Authors: Hill David J , Frazer Astrid , Swenne Ingemar , Wirdnam Paul K , Milner R David G
Published: September 2013

The presence of somatomedin-C/insulin-like growth factor I (SM-C/IGF-I) was investigated in human fetal pancreatic glands obtained after prostaglandin-induced abortion at 14-17 wk of gestation. Pancreatic explants were cultured in medium containing 11.1 or 22.2 mM glucose and 20% fetal calf serum for 8-10 days. During this period they were exposed, on two separate occasions, to serum-free culture medium for 24 h. SM-C/ IGF-I and insulin were measured radioimmunologically in the serum-free media and in acid-ethanol-extracted homogenates of the cultured explants. SM-C/IGF-I was measurable in the conditioned media only after extraction by reverse-phase chromatography to remove somatomedin- binding proteins. On gel filtration at neutral pH of extracted medium samples, the immunoreactive SM-C/IGF-I was recovered in the region of the homogenous peptide with an apparent molecular weight of 7000-8000. Explants cultured in 22.2 mM glucose contained more SM-C/IGF-I and had a tendency to release more of the peptide into the culture medium than explants cultured in 11.1 mM. There was no difference in insulin content or release between the two groups. By immunocytochemistry, SM-C/IGF-I was localized to the β-cells of the endocrine pancreas in both freshly fixed tissue and cultured explants.

We conclude that the human fetal pancreas contains SM-C/IGF-I and secretes the peptide during tissue culture. The presence of SM-C/IGF-I in the islets of Langerhans may contribute to the growth and development of the insulin-producing β-cell.
Alteration of Phenytoin Binding by Glycosylation of Albumin in IDDM
Authors: Kemp Stephen F , Kearns Gregory L , Turley Charles P
Published: September 2013

We measured glycosylated albumin and hemoglobin and serum protein binding of phenytoin in 57 children and adolescents with insulin-dependent diabetes mellitus (IDDM). Serum was incubated with phenytoin to yield concentrations of 15 and 25 mg/L, and a serum ultrafiltrate was prepared from an aliquot of each sample. We observed a linear correlation between glycosylated albumin and the free fraction of phenytoin at serum phenytoin concentrations of 15 mg/L (r = .35, P = .03) and 25 mg/L (r = .40, P = .003). A better correlation existed between the free fraction of phenytoin and total albumin concentrations for both serum concentrations (r = .45, P = .005 for 15 mg/L; r = .56, P = 10−5 for 25 mg/L), whereas the best linear correlation resided between the free fraction of phenytoin and the concentration of nonglycosylated albumin (r = .54, P = .0005for 15 mg/L; r = .63, P < 10−6 for 25 mg/L). There was no correlation between the free fraction of phenytoin and the concentration of glycosylated albumin. Incubation of solutions of glycosylated and nonglycosylated albumin demonstrated significantly lower binding to the glycosylated fraction (P = 8.1 × 10−6). These results indicate that glycosylation of albumin diminishes the affinity of the phenytoin binding site on albumin. This alteration may have clinical significance in that it may alter the disposition of phenytoin in patients with IDDM and produce free phenytoin serum concentrations that are not accurately reflected by total serum phenytoin concentrations.
Time Course of Islet Cell Antibodies and β-Cell Function in Non-Insulin-Dependent Stage of Type I Diabetes
Authors: Kobayashi Tetsuro , Itoh Tokuji , Kosaka Kinori , Sato Kaoru , Tsuji Kimiyoshi
Published: September 2013

The time course of islet cell antibodies (ICA) and serum C-peptides responses (CPRs) to oral glucose tolerance tests (OGTTs) were studied prospectively up to 60 (mean 35) mo in 32 ICA-positive subjects [28 with non-insulin-dependent diabetes (NIDDM) and 4 subjects with impaired glucose tolerance (IGT); mean age 45 yr], 96 matched subjects [56 with NIDDM, 8 with IGT, and 32 normal first-degree relatives of patients with insulin-dependent diabetes (IDDM); mean age 45 yr] who were negative for ICA at the beginning of the study. In addition, the effects of human leukocyte antigens(HLA) on the time course of ICA and (β-cell function were evaluated.

In 10 subjects (8 with NIDDM and 2 with IGT) who were ICA positive, ICA became undetectable, even by sensitive ICA assay, 15 ± 2 mo (mean ± SE) after initiation of this study. In these subjects, integrated serum CPR values (σCPR) and 2-h blood glucose values in response to OGTTs improved significantly (P < .05-.01). In contrast, the remaining 22 subjects who were ICA positive were persistently positive for ICA. CPR and blood glucose responses deteriorated progressively in these 22 subjects, and 7 subjects in this group progressed to the insulin-dependent state. Serum CPR and blood glucose responses to OGTTs showed no remarkable changes in 64 patients (56 with NIDDM and 8 with IGT) and 32 normal first-degree relatives of patients with IDDM who remained negative for ICA throughout the study. The frequencies of HLABW54 and HLA-DR4 in 10 subjects who became ICA negative during the follow-up period were lower than those in 22 subjects with ICA throughout the study (uncorrected P < .02). The frequencies of these two antigens were higher in the 22 subjects with persistently positive ICA than in normal controls (uncorrected P < .02), whereas these differences were not observed in 10 subjects who became ICA negative during the study.

The reversed β-cell function after negative conversion of ICA observed in our study yields a new insight into the natural history of type I diabetes, especially in late-onset cases. It suggests that HLA-related genetic predisposition is a prerequisite to the slowly progressive β-cell destruction through pancreatic autoimmunity.
Polymorphic Human Glucose Transporter Gene (GLUT) is on Chromosome 1p31.3→p35
Authors: Shows Thomas B , Eddy Roger L , Byers Mary G , Fukushima Yoshimitsu , Dehaven Catherine R , Murray Jeffrey C , Bell Graeme I
Published: September 2013

The glucose transporter is a membrane glycoprotein that is involved in the uptake of glucose by most, if not all, animal cells. A cloned cDNA that encodes the human protein was used to map the gene to a specific chromosomal region and to identify a DNA polymorphism. The human gene (designated GLUT) was assigned to chromosome 1p31.3H→p35 by hybridization of the probe to DNA from a panel of human-mouse somatic cell hybrids containing different human chromosomes and by in situ hybridization to isolated metaphase chromosomes. The most likely location of GLUT is in 1p33. A common two-allele restriction-fragment-length polymorphism was identified with Xba I. Diabetes.