bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Deactivation of Proinsulin Action on Glucose Disposal and Hepatic Glucose Production in Normal Man
Authors: Glauber H S , Revers R R , Henry R , Schmeiser L , Wallace P , Kolterman O G , Cohen R M , Rubenstein A H , Galloway J A , Frank B H , Olefsky J M
Published: September 2013

We have studied the deactivation of the in vivo actions of insulin and biosynthetic human proinsulin (recombinant DNA) to stimulate the glucose disposal rate (GDR) and to inhibit hepatic glucose output (HGO) in man. Twelve healthy, lean, young subjects were studied using a modification of the euglycemic glucose clamp technique. Subjects received 4-h infusions on separate occasions of insulin (15 mU/m2/min equivalent to 0.54 μg/m2/min) or proinsulin (2.75 μg/m2/min), achieving steady-state serum levels of 32 ± 3 μU/ml (equivalent to 0.23 ± 0.02 pmol/ml) and 3.7 ± 0.2 pmol/ml, respectively. Suppression of HGO was similar (83–84%) with proinsulin and insulin, but stimulation of GDR above basal was greater with insulin (3.41 ± 0.43 versus 1.98 ± 0.28 mg/kg/min, P < 0.001).

Following cessation of the hormone infusions, serum proinsulin concentration fell in a biphasic fashion with half-times of 25 and 146 min for the two phases. Serum half-disappearance time for insulin was 5 min. Deactivation of the hormone's effects to stimulate GDR was 50% complete by 35 min after insulin and 71 min after proinsulin. In contrast, 50% of the recovery times for the effect on suppression of HGO were 55 min after insulin and 188 min after proinsulin. Serum glucagon levels did not differ significantly after the insulin and proinsulin infusions.

In summary: (1) Deactivation of proinsulin and insulin's effects to suppress HGO proceeds more slowly than deactivation of their effects to stimulate GDR; and (2) There is a markedly prolonged and disproportionately delayed deactivation of proinsulin's effects on suppression of HGO. This later finding may prove of therapeutic value in the treatment of diabetes mellitus.
Reduction by Morphine of Human Postprandial Insulin Release is Secondary to Inhibition of Gastrointestinal Motility
Authors: Sullivan S N , Lee M G , Bloom S R , Lamki L , Dupré J
Published: September 2013

The effect of morphine (0.1 mg/kg) on insulin secretion stimulated by oral, intraduodenal, or intravenous administration of glucose was studied in seven healthy volunteers. When glucose was given intravenously, morphine had no effect on plasma glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), or pancreatic glucagon. Following oral glucose, morphine slowed gastric emptying and reduced plasma concentrations of glucose, insulin, and GIP. During intraduodenal infusion of glucose, insulin concentrations in plasma were also decreased by morphine, an effect best explained by decreased small intestinal transit with delayed absorption of glucose and delayed release of GIP. We conclude that clinically relevant doses of morphine have no direct effect on insulin secretion and that the changes observed were secondary to slowed gastric emptying and small intestinal transit.
The Prevalence of Islet Cell Antibodies in Japanese Insulin-dependent and Non-insulin-dependent Diabetic Patients Studied by Indirect Immunofluorescence and by a New Method
Authors: Kobayashi Tetsuro , Sugimoto Tadao , Itoh Tokuji , Kosaka Kinori , Tanaka Toshiaki , Suwa Seizo , Sato Kaoru , Tsuji Kimiyoshi
Published: September 2013

Islet cell antibodies (ICA) were measured in Japanese patients with insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) by a standard, indirect immunofluorescence method (IF method) and by a newly established, threelayer immunofluorescence method applying a biotin-avidin system (BAS method). In addition, the relationship between ICA and HLA was studied in IDDM patients.

ICA titers detected by the BAS method correlated well with those determined by the standard IF method (rs = 0.987, P < 0.01). The BAS method had about an eightfold higher sensitivity for ICA than the IF method.

The overall prevalence of ICA detected by the BAS method (ICA-BAS) versus that by the IF method (ICAIF) was 41% (82/198) versus 28% (56/198) in IDDM patients and 3% (19/593) versus 2% (14/593) in patients with NIDDM. In IDDM patients, ICA-BAS was all positive <1 mo after the onset of diabetes, while the prevalence of ICA-IF was 83% (20/24) during the same period. The prevalence of ICA-IF decreased rapidly with the duration of disease, reaching a value of 6% (3/55) in the patients with a disease duration of 10 yr or more. The incidence of ICA-BAS also decreased with the duration of disease, although to a lesser degree than ICA-IF. No association was found between HLA types and persistence of ICA-BAS or -IF.

These results suggest that pancreatic autoimmune processes occur in almost all Japanese IDDM patients. Although IDDM is less common in Japan than among Caucasians, the prevalence of ICA seems to be the same. The higher sensitivity of the BAS method may be of significant diagnostic value, especially in patients with a long duration of disease.
Renin Secretion by the Spontaneously Diabetic Rat
Authors: Cohen Andrew J , McCarthy Donna M , Rossetti Ronald R
Published: September 2013

Renal function studies and measurements of in vivo plasma renin activity (PRA), kidney renin content, and renin secretion by isolated, perfused kidneys were performed in spontaneously diabetic and nondiabetic Bio Breeding/Worcester (BB/W) rats. Diabetic animals evidenced hyperglycemia, glycosuria, and plasma volume expansion. After dietary sodium deprivation, plasma volume fell to levels equivalent to those of sodium-deprived, nondiabetic rats.

Dietary sodium deprivation evoked a larger proportional increase in PRA among diabetic than nondiabetic animals, although PRA before sodium restriction was equivalent in the two groups.

Basal renin release (RR) was higher from isolated, perfused kidneys from diabetic rats than from nondiabetic kidneys. Diabetic kidneys, moreover, displayed increased kidney renin content (KRC). By contrast, while isoproterenol (10−5 M) stimulated a nearly fivefold increment in RR from nondiabetic, perfused kidneys, a negligible effect was observed in diabetic kidneys. The dose-response curve of renin secretion (as a proportion of total renal content) in response to isoproterenol was shifted downward. Hence, while KRC and spontaneous RR by isolated, perfused kidneys were increased, the increment in PRA with salt depletion and the renin-secretory response to isoproterenol in vitro were impaired. We propose that specific defects in renin secretion, in particular, the response to betaadrenergic stimulation, may be operative in diabetes.
Decreased Phospholipase A2 Activity in Plasma and Liver in Uncontrolled Diabetes Mellitus: A Defect in the Early Steps of Prostaglandin Synthesis?
Authors: Shakir K M Mohamed , Reed H Lester , O'Brian John T
Published: September 2013

Arachidonic acid metabolites and prostaglandins participate in numerous physiologic functions. An enzyme important in the control of prostaglandin production is phospholipase A2. In this study, we have investigated the changes in plasma and hepatic phospholipase A2 activity in diabetes mellitus. In uncontrolled diabetic patients, the postheparin plasma phospholipase A2 level was 18.7 ± 4,1 U/ml; this value was significantly different from the enzyme activities in control subjects (106 ± 9.8 U/ml) and in controlled diabetic patients (87 ± 7.3 U/ml). In the streptozocin-induced diabetic rat model, the postheparin plasma phospholipase A2 level (1.9 ± 0.45 U/ml) was also decreased when compared with normal (9.4 ±1.6 U/ml) and controlled diabetic rats (7.0 ± 1.3 U/ml). The total hepatic enzyme activity in the uncontrolled diabetic rats was only 21.6% of that seen in control rats. Subcellular fraction studies demonstrated that the enzyme activity is decreased in all fractions in the liver. Liver perfusion studies showed that the heparin-releasable phospholipase A2 activity in the perfusate was significantly decreased in the diabetic rats when compared with control and controlled diabetic animals. We conclude that postheparin plasma and hepatic phospholipase A2 activities are decreased in uncontrolled diabetes mellitus, that the low plasma activity is related to decreased release from the liver, and that the alterations in phospholipase A2 activity in plasma and liver are restored to normal by controlling the diabetic status.
Persistence of Polymicrobial Abscesses in the Poorly Controlled Diabetic Host
Authors: Bessman Alice N , Sapico Francisco L , Tabatabai Meher , Montgomerie John Z
Published: September 2013

Polymicrobial infections are frequently found in soft tissue infections of the lower extremities in diabetic patients. The relative susceptibility to and persistence of soft tissue polymicrobial infections of diabetic and nondiabetic mice using bacteria commonly found in clinical foot infections were studied. Subcutaneous abscesses were induced in three groups of diabetic and nondiabetic mice using: (1) E. coli and enterococcus, (2) enterococcus and Bacteroides fragilis (B. fragilis), and (3) E. coli and B. fragilis. Abscesses were removed at 1 and 2 wk for total colony counts. At 1 wk, there was a significantly greater bacterial growth in the abscesses of the diabetic mice compared with the nondiabetic mice only in the group injected with enterococcus and B. fragilis. There were significantly higher colony counts in the diabetic compared with the nondiabetic mice in all three groups at 2 wk after injection of the bacteria. Two weeks after injection of inocula containing B. fragilis, both in combination with E. coli or enterococcus, all nondiabetic mice had eradicated B. fragilis from the abscesses, but significant numbers of B. fragilis persisted in the abscesses of the diabetic mice. In the diabetic mice, the presence of enterococci was more synergistic for growth of B. fragilis than was the presence of E. coli.

These studies demonstrate that the bacteria of polymicrobial soft tissue infections persist for a longer period of time in the diabetic compared with the nondiabetic host. In addition, B. fragilis has increased pathogenicity in the diabetic compared with the nondiabetic host, particularly in the presence of enterococci.
Tolbutamide Increases Hypothalamic Serotonin Activity in the Rat
Authors: Grunstein H S , Smythe G A , Bradshaw J E , Compton P J
Published: September 2013

Sulfonylureas are potent hypoglycemic agents; however, their mechanism of action remains incompletely understood. Recent data indicate that hypothalamic norepinephrine (NE) plays a major role in mediating the central neural regulation of blood glucose. We therefore examined whether the sulfonylurea tolbutamide might lower serum glucose via an effect on hypothalamic NE neuronal activity, and compared the effects with those of 2-deoxyglucose-induced neuroglycopenia and of chronic insulin administration. Serum glucose levels fell and serum insulin levels rose 10, 20, and 30 min after acute tolbutamide injection. Serum glucose concentrations were reduced after chronic tolbutamide administered in drinking water, but serum insulin did not change. Hypothalamic NE neuronal activity was increased 10 min after tolbutamide administration, but not at the later times, nor during chronic tolbutamide administration. However, consistent with a rise in serotonin (5-HT) neuronal activity, hypothalamic 5-hydroxyindoleacetic acid (5-HIAA) and the 5-HIAA/5-HT ratio rose 30 min after acute tolbutamide and during chronic tolbutamide administration. This rise was not due to neuroglycopenia per se, since hypothalamic NE neuronal activity was increased and hypothalamic 5-HT neuronal activity was reduced after 2-deoxyglucose induced neuroglycopenia. Furthermore, the effect of chronic tolbutamide contrasted with that of chronic insulin administration where hypothalamic NE neuronal activity was increased, while hypothalamic 5-HT neuronal activity was unchanged. We conclude that tolbutamide does not lower serum glucose via a direct effect on hypothalamic NE neuronal activity; however, we note that tolbutamide specifically increases hypothalamic 5-HT neuronal activity. We hypothesize that this rise in hypothalamic 5-HT neuronal activity may be involved in the extrapancreatic hypoglycemic effect of tolbutamide.
Guinea Pig Glucagon Differs From Other Mammalian Glucagons
Authors: Huang C -G , Eng J , Pan Y -C E , Hulmes J D , Yalow R S
Published: September 2013

Mammalian glucagon is thought to be highly conserved. Glucagons from pig, cow, human, rat, and hamster have identical amino acid sequences, whereas the amino acid contents of rabbit and camel glucagons are consistent with this 29-amino acid sequence. It had earlier been reported that guinea pig (GP) glucagon contains 40 amino acids. In the current study, glucagon was purified from two GP pancreata by a series of three HPLC steps after acid-alcohol extraction and acetone precipitation. GP glucagon is a 29-amino acid peptide that differs from other mammalian glucagons by substitution of Gin for Asp in position 21, Leu for Val in position 23, Lys for Gin in position 24, Leu for Met in position 27, and Val for Thr in position 29. In view of the marked changes in the COOH-terminal of GP glucagon, receptor binding studies were performed using both rat and GP liver membranes. Labeled synthetic porcine glucagon has similar binding in the two systems and its binding is inhibited to a similar degree by synthetic porcine glucagon, whereas GP glucagon is 10-fold less potent at inhibiting binding in both systems. This suggests that glucagon receptor binding sites in the GP are evolutionarily more conserved than is GP glucagon.
Insulin Decreases H4IIE Cell PEPCK mRNA by a Mechanism That Does Not Involve cAMP
Authors: Beale Elmus G , Koch Stephen R , Brotherton Abigail F A , Sheorain Virender S , Granner Daryl K
Published: September 2013

Insulin is thought to influence some metabolic events by decreasing the intracellular concentration of cyclic AMP (cAMP). To test whether this explains the repression of hepatic phosphoenolpyruvate carboxykinase (PEPCK) by insulin we measured intracellular cAMP, cAMP-dependent protein kinase; mRNAPEPCK, and PEPCK gene transcription in cultured Reuber H4IIE hepatoma cells treated with forskolin with and without insulin. In untreated cells, the concentration of cAMP was 2.9 pmol/mg of protein. Forskolin at 1,10, and 50 μM increased the level of cAMP to 9.2, 35.8, and 115 pmol/mg of protein, respectively; 5 nM insulin had no significant effect on these cAMP concentrations. In untreated cells, the activity ratio of cAMP-dependent protein kinase was 0.43, and 50 μM forskolin increased this to 0.96; insulin had no effect on this ratio at times from 15–180 min. In untreated cells mRNAPEPCK bound 15 cpm of a 32P-labeled cDNA probe per microgram of total cellular RNA. Forskolin, at 1, 10, and 50 μM, increased this to 48, 96, and 115 cpm/μg RNA. Insulin (5 nM), in combination with 0, 1, 10, and 50 μM forskolin, decreased the concentration of mRNAPEPCK to 5, 8, 23, and 29 cpm/μg RNA, respectively. Finally, the rate of transcription of the PEPCK gene was 85, 168, 630, 823, and 884 parts per million (ppm) in H4IIE cells treated for 30 min with 0, 1, 5, 10, and 50 μM forskolin, respectively, while the corresponding rates in the presence of 5 nM insulin were 49, 45, 84, 85, and 136 ppm. These results demonstrate that insulin represses mRNAPEPCK and PEPCK gene transcription in H4IIE cells by a mechanism that is independent of the regulation of intracellular cAMP concentration and cAMP-dependent protein kinase activity.
Effect of Sorbinil on Blood-Retinal Barrier in Early Diabetic Retinopathy
Authors: Cunha-Vaz Jose G , Mota Carolina C , Leite Eugenio C , Abreu Jose R , Ruas Manuel A
Published: September 2013

To study the effect of sorbinil on the alteration of the blood-retinal barrier, 32 adult-onset, non-insulin-dependent diabetic patients with minimal or no retinopathy were randomly assigned to receive either oral sorbinil (250 mg once a day) or a placebo for 6 mo. All patients underwent fundus photography, fluorescein angiography, and vitreous fluorophotometry before treatment and at 3 and 6 mo after treatment. Vitreous fluorophotometry data showed that the alteration of the blood-retinal barrier increased significantly less in the sorbinil-treated group compared with the placebo group during the 6-mo study period. Side effects were limited to hypersensitivity reactions, with skin rash and fever, in only 2 of the 16 patients who received the drug. These hypersensitivity reactions disappeared with discontinuation of the medication. Aldose-reductase inhibition may play an important role in stabilization of the blood-retinal barrier in early diabetic retinopathy.
Relation Between Insulin Antibody and Complement-Fixing Islet Cell Antibody at Clinical Diagnosis of IDDM
Authors: Karjalainen J , Knip M , Mustonen A , Ilonen J , Åkerblom H K
Published: September 2013

To test the hypothesis that insulin-binding antibodies (IBAs) appearing in the circulation before insulin treatment are markers of β-cell damage, we studied the prevalence of IBAs and both conventional (IF-ICAs)- and complement (CF-ICAs)-fixing cytoplasmic islet cell antibodies in 60 newly diagnosed diabetic children with a mean age of 9.5 yr. Seventeen (28.3%) had an insulin binding exceeding the upper range (2.8%) of that observed in 68 age-matched controls. The IBA-positive subjects were characterized by a younger age of onset [6.2 ± 4.0 (SD) vs. 10.8 ± 3.2 yr; P < 0.001], lower glycosylated hemoglobin A, levels (14.1 ± 3.1 vs. 16.0 ± 3.0%; P < 0.05), lower serum C-peptide concentrations (0.12 ± 0.07 vs. 0.20 ± 0.17 nmol/L; P < 0.05), and an increased frequency of HLA-Dw4 (9/13 vs. 11/37; P < 0.05). There was no significant relation between IBAs and serum C-peptide concentrations after age adjustment by multiple regression analysis. Forty-three children (75%) were positive for IF-ICA and 38 (63.3%) for CF-ICA. Twelve IBA-positive diabetics (70.6%) had IFICA as well as CF-ICA in their serum. No association could be observed between IBA and either IF-ICA or CF-ICA, however. The results suggest that IBAs developing before diagnosis serve as an indicator of clinical and genetic heterogeneity within IDDM rather than as a marker of autoimmune β-cell destruction.
Long-Term Plasma Glucose Normalization in Experimental Diabetic Rats With Macroencapsulated Implants of Benign Human Insulinomas
Authors: Altman J J , Houlbert D , Callard P , McMillan P , Solomon B A , Rosen J , Galletti P M
Published: September 2013

Permselective tubular membranes (1 mm i.d.) were filled with fragments of nine freshly resected human insulinomas, closed at both ends, and implanted in the peritoneal cavity of 30 streptozocin-induced diabetic rats. In 14 animals, nonfasting plasma glucose (PG) and insulin levels were normalized by these immunoprotected transplants for up to 1 yr (PG from 520 ± 12 to 142 ± 3 mg/100 ml; insulin from 6 ± 0.5 to 44 ± 3 μU/ml). These animals showed the same weight gain after 12 mo of observation as 20 controls. The remaining 16 animals showed an incomplete or transient correction of their diabetes and survived 4–6 mo, versus <8 wk in untreated animals. Removal of the membraneencapsulated insulin-secreting tissue from 8 successfully treated rats led to hyperglycemia and death within 10 days. Histology and electron microscopy of insulinoma tissue retrieved after long-term implantation showed functionally active endocrine cells and no evidence of graft rejection. In vitro perifusion gave similar results for encapsulated and nonencapsulated insulinoma tissue. The amount of insulin secreted was quite variable, and responsiveness of the insulinoma to changes in glucose concentration of the surrounding medium was observed in three out of the five tumors studied. These observations establish the effectiveness of immunoseparation by a synthetic membrane in a pancreatic xenograft model.
Binding and Internalization of Insulin and Insulin-Like Growth Factors by Isolated Brain Microvessels
Authors: Frank H J L , Pardridge W M , Morris W L , Rosenfeld R G , Choi T B
Published: September 2013

Isolated brain capillaries were used as a model system to test for binding and internalization of insulin and insulin-like growth factors (IGF) I and II. At 37°C, the maximum specific binding of the 125I-labeled peptides was 48.0 ± 0.8%/mg capillary protein for IGF I, 40.6 ± 1.4% for IGF II, and 15.1 ± 0.6% for insulin. The concentration of unlabeled peptide needed to cause a 50% decrease in the maximum binding (ID50)was 22 ng/ml (2.9 nM), 25 ng/ml (3.3 nM), and 7 ng/ml (1.2 nM) for IGF I, IGF II, andinsulin, respectively. Unlabeled insulin competed poorly for the IGF I receptor, requiring 5000 ng/ml (667 nM) to cause a 50% reduction in binding, and did not compete at all for the IGF II receptor at concentrations up to 105 ng/ml (17.8 μM).

The IGF I receptor was further characterized by reduced polyacrylamide gel electrophoresis ofthe disuccinimidyl suberate cross-linked 125I-labeled IGF I receptor. The gel showed a distinct band at 133,000 M1 that was abolished by 0.6 μg/ml (80 nM) unlabeled IGF I but not by 10.0 ng/ml (1780 nM) unlabeled insulin.

Peptide internalization was monitored by the acidwash technique. Only 22% of the bound IGF I was internalized, but 50% of the insulin and 43% of the IGF II were acid resistant. Capillaries prelabeled with internalized 125I-insulin could then export radioactivity into fresh, insulin-free media in a time- and temperature-dependent manner. However, high-performance liquid chromatography (HPLC) and trichloroacetic acid (TCA) analysis of the released material showedthat it consisted mostly of degraded peptide.

These studies show that brain capillaries have separate receptors for insulin, IGF I, and IGFII. The endocytosis of these peptides is in the order of insulin > IGF II >IGF I, the same order as their distribution in cerebrospinal fluid (CSF) and brain, based on published data. Although the HPLC data do not support the general conclusion that the blood-brain barrier functions as a selective peptide-hormone transporter, this may be the result of cellular damage because the capillaries are ATP depleted.
Characterization of Stages in Development of Obesity-Diabetes Syndrome in Sand Rat (Psammomys obesus)
Authors: Kalderon Bella , Gutman Alisa , Levy Emile , Shafrir Eleazar , Adler Jonathan H
Published: September 2013

Sand rats (Psammomys obesus) maintained on a diet providing a free choice between laboratory chow and salt bush (Atriplex halimus) were classified into four groups differing in extent of the diabetic syndrome: A, normoglycemic-normoinsulinemic; B, normoglycemichyperinsulinemic; C, hyperglycemic-hyperinsulinemic; or D, hyperglycemic with reduced insulin levels. The metabolic pattern of these groups was characterized by measuring 1) the uptake of fatty acid-labeled, very-lowdensity lipoprotein-borne triglycerides (VLDL-TG) and [3H]%-2-deoxyglucose (2-DOG) into muscle and adipose tissues; 2) incorporation of [14C]alanine into glycogen in vivo; 3) gluconeogenesis from lactate, pyruvate, and alanine in hepatocytes; 4) the effect of insulin on glycogen synthesis from glucose; 5) the oxidation of albumin-bound [1-14C]palmitate and [14C]glucose in strips of soleus muscle; 6) activities of muscle and adipose tissue lipoprotein lipase; and 7) activities of rate-limiting enzymes of glycolysis, gluconeogenesis, and fatty acid synthesis in liver. In group A, uptake of VLDL-TG and activity of lipoprotein lipase were higher in adipose tissue and lower in muscle than in albino rats. In the liver, gluconeogenesis and the activity of phosphoenolpyruvate carboxykinase, as well as lipid synthesis and the activity of NAOP-malate dehydrogenase,were higher than in albino rats, whereas activity of pyruvate kinase was lower. In group B, uptake of VLDL-TG by adipose tissue and muscle and lipoprotein lipase activity were similar or higher than in group A. Uptake of 2-DOG by muscle and adipose tissue and activity of liver phosphoenolpyruvate carboxykinase were lower than in group A. In groups C and D, uptake of VLDL-TG and lipoprotein lipase activity in muscle were further increased. In adipose tissue a progressive decrease in VLDL-TG uptake and lipoprotein lipase activity was found, and uptake of 2-DOG by muscle and adipose tissue was further reduced. In the liver, gluconeogenesis was increased, and activity of phosphoenolpyruvate carboxykinase reached a maximum in group D. These results suggest that in the hyperinsulinemic stage (group B), uptake of glucose by muscle and adipose tissue is reduced, but insulin suppresses gluconeogenesis and stimulates hepatic synthesis and adipose tissue uptake of TG. Hyperglycemia manifests itself when insulin resistance results in increased gluconeogenesis and a further reduction in peripheral glucose uptake. These characteristics can be regarded as a model for the development of type II diabetes in humans evoked by nutritional affluence.
Insulin Deficiency Alters Cellular Cholesterol Metabolism in Murine Macrophages
Authors: Kraemer Fredric B
Published: September 2013

Mice made insulin deficient by the injection of streptozocin develop hyperglycemie and hypertriglyceridemia with triglyceride-rich, very-low-density lipoproteins (VLDLs). Thioglycolate-elicited peritoneal macrophages freshly isolated from insulin-deficient mice have increased activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase, which is reflected in a greater rate of cholesterol synthesis by these macrophages. In contrast, thioglycolate-elicited macrophages from control mice with diet-induced hypertriglyceridemia had normal levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Cell surface receptors responsible for VLDL uptake are decreased in macrophages isolated from insulin-deficient mice, although receptors for acetylated low-density lipoproteins are not altered. Insulin treatment of insulin-deficient mice lowers plasma glucose and triglyceride concentrations. Additionally, insulin treatment returns the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase and the rate of cholesterol synthesis in thioglycolate-elicited macrophages to normal while increasing the number of receptors responsible for VLDL uptake. It is suggested that the increases in 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and the rate of cholesterol synthesis in macrophages isolated from insulin-deficient mice are secondary to the reduction in the number of receptors responsible for VLDL uptake induced by insulin deficiency. These alterations in the cholesterol metabolism of macrophages occurring with insulin deficiency may have important implications for the atherosclerotic process in diabetes mellitus.
Relative Importance of First- and Second-Phase Insulin Secretion in Glucose Homeostasis in Conscious Dog: II. Effects on Gluconeogenesis
Authors: Steiner Kurt E , Mouton Stephanie M , Williams Philip E , Lacy William W , Cherrington Alan D
Published: September 2013

The normal pancreatic response to an exogenous glucagon infusion is a biphasic release of insulin. In our study the ability of each component of insulin release to counter the effects of the glucagon on gluconeogenesis and alanine metabolism was assessed by mimicking first- and/or second-phase insulin release with infusions of somatostatin and intraportal insulin. When a fourfold increase in glucagon was brought about in the presence of fixed basal insulin release, there was a large increase in overall glucose production and gluconeogenesis. The increase in the conversion of [14C]alanine into [14C]glucose (169 ± 42%, P < .05) was accompanied by an increase in the fractional extraction of alanine by the liver (FEA 0.32 ± 0.06 to 0.66 ± 0.10, P < .05) and net hepatic alanine uptake (NHAU 2.97 ± 0.45 to 4.61 ± 0.48 μmol kg1 · min1 P < .05). Simulated first-phase insulin release had no effect on the ability of glucagon to increase FEA (0.32 ± 0.03 to 0.66 ± 0.03, P < .05) or NHAU (3.69 ± 0.80 to 5.10 ± 0.69 μmol · kg1 · min−1 P < .05) but did limit the increase in overall gluconeogenic conversion (114 ± 37%). Second-phase insulin release had no effect on either the glucagon-induced increase in FEA (0.35 ± 0.08 to 0.73 ± 0.04) or NHAU (3.35 ± 0.92 to 5.13 ± 0.85 μmol · kg−1 · min−1) but completely inhibited the increase in overall gluconeogenic conversion. Combined first- and second-phase insulin release was also unable to prevent the glucagon-induced increase in FEA (0.35 ± 0.09 to 0.65 ± 0.06, P < .05) and-NHAU (2.59 ± 0.56 to 3.50 ± 0.37 μmol · kg−1 · min−1) but completely inhibited the glucagon-induced rise in gluconeogenic conversion. These data show that the glucagon-induced increase in gluconeogenic conversion was remarkably sensitive to relatively small (≃8 μU/ml) changes in circulating insulin. Even a brief (5-min) pulse of insulin markedly reduced the effect of glucagon on the overall gluconeogenic process for a prolonged period. Furthermore, the inhibitory action of insulin appeared to occur within the hepatocyte rather than at the cell membrane because the increase in the fractional extraction of alanine by the liver and indeed the rise in hepatic alanine uptake caused by glucagon were unaffected by the increase in insulin.
Relationships Between Growth Factors (Somatomedin-C and Growth Hormone) and Body Development, Metabolic Control, and Retinal Changes in Children and Adolescents With IDDM
Authors: Salardi Silvana , Cacciari Emanuele , Ballardini Donatella , Righetti Francesca , Capelli Maurizio , Cicognani Alessandro , Zucchini Stefano , Natali Gabriele , Tassinari Davide
Published: September 2013

We used the radioimmunoassay (RIA) method to determine somatomedin-C (SmC) basal values in 59 diabetic children and adolescents (20 prepubertal and 39 pubertal subjects; age range 2.75–20.16 yr; duration of diabetes 0.08–15.83 yr) and in 274 control subjects. In comparing diabetic subjects with controls, we considered only those 50 diabetic subjects who were age matched with the controls, i.e., those not over 16 yr chronological age. SmC basal levels in pubertal diabetic patients were no different from those of pubertal age-matched control children, whereas in prepubertal diabetic patients SmC was significantly lower than in the respective control children (P < .001). No correlation was found between the z score for SmC (i.e., the number of standard deviations each SmC level is from the age- and sex-normalized mean) and duration of disease, velocity standard deviation score, severity of fluoroangiographic retinal changes, basal C-peptide values and HbA, levels. No differences were encountered in mean SmC and SmC z-score values in the separate groups of poorly, fairly, and well-controlled diabetic children, in the groups with and without residual pancreatic activity, and in the group with and without retinal changes. In 16 of the pubertal diabetics and in 15 pubertal controls, serum glucose, growth hormone (GH), and SmC concentrations were determined during the night. The integrated nocturnal secretion of SmC was no different in diabetics than in controls, whereas the integrated nocturnal secretion of GH was significantly (P < .025) higher in diabetics than in controls. These data suggest a partial block in somatomedin production, which would be compensated by a hypersecretion of GH through a negative-feedback relationship. On the other hand, it may be that GH hypersecretion is primary and that the normal or low SmC secretion is a response to low-efficiency GH.
Modulation of Insulin Secretion by Pancreatic Ganglionic Nicotinic Receptors
Authors: Stagner John I , Samols Ellis
Published: September 2013

Autonomie ganglia may be regulated, in part, by nicotinic receptors. To test whether basal insulin secretion may be modulated by an endogenous pancreatic ganglionic mechanism, the effects of ganglionic pre- and postsynaptic nicotinic receptor antagonism were studied in the in vitro canine pancreas. Combined infusion of atropine, phentolamine, and propranolol had no affect on insulin secretion (P < .30). Presynaptic nicotinic receptor blockade by β-bungarotoxin (β-BuTX) in combination with atropine and phentolamine reduced mean insulin secretion (78 ± 18 U/ml, P < .0025) from preinfusion concentrations (287 ± 43 U/ml). The decrease in insulin secretion resulting from BuTX, atropine, and phentolamine was prevented by the addition of either specific postsynaptic nicotinic receptor blockade by α-bungarotoxin (P < .05) or propranolol (P < .005). Because it is known that postsynaptic nicotinic receptor agonism may stimulate the intragan-glionic release of norepinephrine, these results suggest that nicotinic receptors are present at the ganglionic level in the pancreas and modulate insulin secretion by a complex intraganglionic mechanism. The postulated ganglionic nicotinic receptor-mediated mechanism may operate by the interaction of a β-adrenergic inhibitory component, which may be activated by intraganglionic norepinephrine, and a stimulatory nonmuscar-inic nonadrenergic (possibly peptidergic) component, which may be activated in the absence of intraganglionic norepinephrine.
Vitamin D Metabolites and Their Binding Protein in Adult Diabetic Patients
Authors: Nyomba B L , Bouillon R , Bidingija M , Kandjingu K. , Moor P De
Published: September 2013

Vitamin D metabolites and vitamin D—binding protein were measured in the serum of nonketotic Bantu and Caucasian insulin-requiring diabetic subjects from Zaire and Belgium, respectively. In Caucasian diabetics, whether untreated (N = 18) or insulin treated (N = 26), no abnormalities were found. The Bantu diabetics (N = 20) were more insulin-deficient and had a poorer glucose control than the Caucasians. They presented, compared with Bantu controls, a significant decrease in the serum concentrations of 25-hydroxy-vitamin D3 (26 ± 10 vs. 35 ± 14 μg/L, P < .01), 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] (38 ± 15 vs. 58 ± 17 ng/L, P < .001), and vitamin D-binding protein (303 ± 55 vs. 356 ± 41 mg/L, P < .001). The decreased concentrations of vitamin D metabolites in the adult Bantu diabetic patients may be partly explained by a concomitant decrease in the concentration of vitamin D-binding protein, possibly due to insulin deficiency. The ratio between the molar concentrations of 1,25-(OH)2D3 and vitamin D-binding protein, used as an index of the free hormonal level, was also decreased, in association with a decreased serum calcium level.

In conclusion, no abnormalities in vitamin D metabolism were found in Caucasian insulin-dependent diabetics, whereas low serum 1,25(OH)2D3 concentrations and hypocalcemie were found in poorly controlled Bantu diabetic subjects.
Glycation of Skin Collagen in Type I Diabetes Mellitus: Correlation With Long-Term Complications
Authors: Vishwanath Vasanth , Frank Kay E , Elmets Craig A , Dauchot Paul J , Monnier Vincent M
Published: September 2013

Nonenzymatic glycosylation (glycation) of collagen was measured by boronate affinity chromatography in skin biopsies from 41 type I diabetics with mean duration of diabetes of 25 yr (range 20–40 yr) and from 25 age-matched controls. Mean level of Amadori products was significantly increased in diabetic [7.85 ± 1.78 (SD) nmol/mg collagen] versus control subjects [3.34 ± 1.06 (SD) nmol/mg collagen, P < .001] but did not correlate with age, diabetes duration, or severity of retinopathy, nephropathy, arterial stiffness, and joint stiffness. Similarly, mean collagen content per biopsies was 42% increased in diabetic versus control subjects (P < .001) but did not correlate with age, diabetes duration, or severity of complications. A weak but positive correlation between glycohemoglobin level and glycation of skin collagen was observed. These results indicate that Amadori products cannot explain by themselves the pathogenesis of diabetic complications unless individual tissue response to glycation is different in subjects with and without complication. They do not exclude a role for the late stages of the Maillard reaction, nonenzymatic browning, in the formation of some of these complications.
Gm, Km, and HLA in Insulin-Dependent Type I Diabetes Mellitus: A Log-Linear Analysis of Association
Authors: Rich S S , Weitkamp L R , Guttormsen S , Barbosa J
Published: September 2013

Two hundred sixty families, in which at least one family member had insulin-dependent (type I) diabetes mellitus (IDDM), were typed for HLA antigens and the Gm and Km al loty pes. Frequencies of Gm and Km allotypes in the diabetic subjects were compared with family controls (oldest nondiabetic sibling within a family). There were no significant differences between patients and controls for either Gm or Km allotype frequencies considered individually. When the log-linear model was used to analyze subjects and sibling controls, three significant findings emerged. First, there was a significant HLA-Gm interaction, indicating nonrandom segregation of HLA antigens with Gm allotypes, regardless of disease status. Second, there was, as expected, a significant HLA-IDDM interaction, indicating that HLA type is nonrandom with respect to IDDM status. Third, there was a significant HLA-sex-Gm-IDDM interaction, indicating that combinations of HLA antigens, Gm allotypes, and sex may play an important role in defining risk for IDDM. Thus, Gm and sex interacting with HLA may reflect the influence of an unlinked modifier previously hypothesized for IDDM pathogenesis.
Impairment of Lymphocyte-Suppressive System in Recent-Onset Insulin-Dependent Diabetes Mellitus: Correlation With Metabolic Control
Authors: Crosti F , Secchi A , Ferrero E , Falqui L , Inverardi L , Pontiroli A E , Ciboddo G F , Pavoni D , Protti P , Rugarli C , Pozza G
Published: September 2013

Impairment of suppressor-cell activity may be important in the pathogenesis and maintenance of insulindependent diabetes mellitus (IDDM). In 23 recent-onset IDDM patients, lymphocyte sensitivity in vitro to theophylline was tested both in basal conditions and after improvement of metabolic control. This pharmacologic agent is mainly effective on a lymphocytic subpopulation with phenotypic and functional suppressive features. Peripheral blood lymphocytes from IDDM patients showed a loss of theophylline sensitivity, identified as inhibition of both E-rosette formation and blastogenic response to polyclonal mitogens concanavalin A (ConA) and phytohemagglutinin (PHA). An inverse relationship was demonstrated between the theophylline-induced suppression of ConA blastogenic response and blood glucose and glycosylated hemoglobin levels (P < .01). Metabolic control seemed to be important even in relation to lymphocyte subpopulation distribution. In IDDM patients we found a significant (P < .05) reduction of OKT4+ lymphocytes that is correlated with blood glucose and glycosylated hemoglobin levels (P < .01). The improvement of metabolic control led to recovery of theophylline sensitivity. We suggest a deficiency in a suppressive system that could be involved in IDDM onset and the possible role of metabolic control in the impairment of some immunologic functions reported with this pathologic condition.
Further Evidence Implicating Diacylglycerol Generation and Protein Kinase C Activation in Agonist-Induced Increases in Glucose Uptake: Insulin-Like Effects of Phenylephrine in BC3H-1 Myocytes
Authors: Farese R V , Rosic N , Standaert M , Babischkin J , Cooper D R , Davis J S , Pollet R J
Published: September 2013

We have previously suggested that insulin effects on 2-deoxyglucose (2-DOG) uptake in BC3H-1 myocytes are due to increases in de novo phospholipid synthesis, diacylglycerol generation, and protein kinase C activation. To test this hypothesis further, we examined the effects of phenylephrine, an agonist that increases diacylglycerol and protein kinase C activity through phospholipase C activation. As evidence for phospholipase activation in BC3H-1 myocytes, we found that phenylephrine increased 7) acute 32PO4 incorporation into phosphatidic acid and phosphatidylinositol, 2) generation of [3H]inositol phosphates from prelabeled [3H]inositol phospholipids, 3) cytosolic Ca2+, and 4) membrane-bound protein kinase C. Phenylephrine also provoked dose-related increases in [3H]-DOG uptake that were similar in magnitude and time course to those induced by insulin. As with insulin, phenylephrine effects on 2-DOG uptake were not apparent in myocytes that were maximally stimulated with 12-O- tetradecanoylphorbol-13-acetate, a diacylglycerol analogue that activates protein kinase C. These findings support our hypothesis that diacylglycerol generation and protein kinase C activation may be important in the stimulation of glucose uptake by agents such as phenylephrine and insulin that activate the phosphoinositide cycle.
Three-Allele Synergistic Mixed Model for Insulin-Dependent Diabetes Mellitus
Authors: Louis E J , Thomson G
Published: September 2013

Application of the method of antigen genotype frequencies among patients to HLA-DR data pertaining to insulin-dependent diabetes mellitus substantiates the results of Rotter et al. and Thomson that a singlepredisposing- allele model is incompatible with the observed data. The method is also modified to take into account the possibility of blanks (untyped antigens) in the assumed homozygotes. The rejection of all intermediate single-allele models is still obtained. A minimum of two HLA-linked predisposing components are necessary to account for the data. The patterns observed are consistent with a three-allele model, in which the two predisposing alleles interact synergistically (negative complementation). Furthermore, a model in which the DR3-associated predisposition allele is recessive in the absence of the other allele and the DR4-associated predisposing allele is additive (dominant) in the absence of the other is more consistent with the data than a model in which both alleles are recessive or additive in the absence of the other.
Apparent Epidemic of Insulin-Dependent Diabetes Mellitus in Midwestern Poland
Authors: Rewers Marian , LaPorte Ronald E , Walczak Mieczyslaw , Dmochowski Krzysztof , Bogaczynska Elzbieta
Published: September 2013

There is no information concerning the risk of developing insulin-dependent diabetes mellitus (IDDM) in eastern Europe. An IDDM registry has been developed in Midwest Poland for 1970-1984. The risk of developing IDDM in Polish children was determined through utilization of the registry. The incidence of IDDM in Polish children was very low compared with other Caucasian populations. There was a major increase in risk beginning in 1982; the incidence almost doubled from 3.5/100,000 in 1970-1981 to 6.6/100,000 in 1982-1984. The pattern of IDDM in the high-risk period was different from that in the low-risk period, with an altered seasonal pattern and unusual increased incidence in younger children. The rapid increase in incidence as well as altered epidemiologic patterns during this period suggest that major alterations of environmental factors were responsible for the change in risk.
Transcomplementation of HLA Genes in IDDM: HLA-DQ α and β-Chains Produce Hybrid Molecules in DR3/4 Heterozygotes
Authors: Nepom Barbara S , Schwarz David , Palmer Jerry P , Nepom Gerald T
Published: September 2013

The HLA association with insulin-dependent diabetes mellitus is highest among individuals heterozygous for DR3 and DR4. To investigate potential mechanisms to account for this association, we performed two-dimensional gel-electrophoretic analysis of HLA molecules from DR3/4 heterozygous patients. These studies demonstrated hybrid molecular dimers corresponding to products of HLA-DQ genes linked to DR3 and DR4, i.e., the DQw2 and DQw3 genes, respectively. Two types of OQ molecules were found: immunoprecipitation by DQw3-specific monoclonal antibody 17.15 identified a DQw3 β-chain associating with a DQw3 α-chain and a DQw3 β-chain associating with a DQw2 α-chain. The identity of α- and β-chains comprising these hybrid molecules was confirmed by HPLC peptide-map analysis. Several characteristic peptide peaks identified both DQw2 and DQw3 α-chains associated with DQw3 β-chains. The formation of such DQα(DQw2)- Dqβ(DQw3) dimers potentially contributes a direct molecular mechanism for HLA-associated contributions to disease in DR3/DR4 heterozygotes.
Defective Epinephrine and Growth Hormone Responses in Type I Diabetes Are Stimulus Specific
Authors: Hirsch Barbara R , Shamoon Harry
Published: September 2013

The counter regulatory hormone responses to hypoglycemia and a non-glucose stimulus, exercise, were evaluated in 18 subjects with type I diabetes and in 9 normal controls. Subjects with diabetes had no overt neuropathy, with R-R variations and postural plasma norepinephrine increments that were similar to those of controls. The diabetic subjects exhibited normal increments in plasma growth hormone (GH), norepinephrine, and cortisol but blunted or absent responses in plasma epinephrine and glucagon when hypoglycemia was severe (<40 mg/dl). During a 60-min clamped reduction in plasma glucose at ∼65 mg/dl, plasma GH and epinephrine increased 6- to 15-fold in controls but 2- to 4-fold in diabetics (P < .05). However, when subjects were exercised at this plasma glucose level (50 W for 10 min), plasma epinephrine and GH in diabetics rose markedly by 150–400% to attain the peaks reached by the controls. Plasma norepinephrine and cortisol increased to similar levels in both groups, and plasma glucagon was not significantly changed. We conclude that epinephrine and GH secretion in response to hypoglycemia are reduced in type I diabetes but that these defects are stimulus specific because the responses to exercise are not reduced.
Modulation of Insulin Action on 2-Deoxyglucose Uptake by Chloroquine in Chick Embryo Fibroblasts
Authors: Cynober Luc , Aussel Christian , Vaubourdolle Michel , Agneray Jean , Ekindjian Ohvanesse G
Published: September 2013

Blazar et al. recently found that chloroquine therapy decreased intravenous insulin requirements in a case of extreme insulin resistance. However, no relationship has been shown to exist between insulin degradation and the stimulation of glucose uptake. In this study we investigate the action of insulin on glucose uptake by the ability of this hormone to stimulate 2-deoxyglucose. The effect on α-aminoisobutyrate uptake, which is known to be insulin sensitive, is also investigated. Cell-associated 125l-labeled insulin and trichloroacetic acid-soluble and -precipitable substances were measured in parallel. Chloroquine increased insulin-stimulated uptake of 2-deoxyglucose and a-aminoisobutyrate. Three hours were required for this effect to appear, and it did not depend on DNA synthesis. Chloroquine also increased cell-associated insulin and slightly decreased the percentage of trichloroacetic acid-soluble products. Methylamine affected neither nutrient uptake processes nor insulin binding and degradation; however, it did abolish the effect of chloroquine on these parameters. These data suggest that in chick embryo fibroblasts a relationship may exist between the increase in undegraded cell-associated insulin and the ability of the hormone to stimulate sugar and amino acid uptake.