bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Met-Enkephalin and Naloxone on Somatostatin and Insulin Secretion from the Isolated, Perfused Rat Pancreas
Authors: Scalac-Guénot Dominique Di , McIntosh Christopher H S 
Published: September 2013

The effect of met-enkephalin and the opiate antagonist, naloxone, on somatostatin and insulin secretion from the isolated, perfused rat pancreas has been studied during perfusion with 300 mg/dl glucose. In response to a gradient of met-enkephalin from 0 to 10−5 M, release of somatostatin was inhibited at low concentrations and stimulated at high concentrations. However, both low and high concentrations of metenkephalin stimulated insulin secretion. A gradient of met-enkephalin from 0 to 10−6 M caused only an inhibition of somatostatin release, whereas insulin release was stimulated.
The effects of met-enkephalin on somatostatin release were antagonized by naloxone (106 M). The metenkephalin-induced insulin secretion was partially, but not completely, blocked by naloxone. Naloxone (10−6 M) alone changed the endocrine secretions by decreasing somatostatin release and by stimulating insulin release. Met-enkephalin may, therefore, be a physiologic regulator of pancreatic endocrine secretion.
Insulin Gene Analysis in a Family with Maturity-onset Diabetes of the Young
Authors: Andreone Teresa , Fajans Stefan , Rotwein Peter , Skolnick Mark , Permutt M Alan 
Published: September 2013

The insulin gene locus has been studied in a large kindred with maturity-onset diabetes of the young (MODY) characterized by hypoinsulinemia. DNA was isolated from peripheral leukocytes of 42 family members and 5 spouses. A highly polymorphic region in the 5'-flanking portion of the human insulin gene provided an opportunity for linkage analysis. The presence of three different length polymorphisms of +1600 base pairs (bp), −50 bp, and −150 bp different from the common size allele allowed haplotype assignment of insulin alleles. The hypothesis of linkage was tested by calculating the log of the ratio of the likelihood of the hypothesis of linkage to that of the hypothesis of nonlinkage (LOD score) at a given recombination distance between the insulin polymorphism and the diabetes locus. At a recombination frequency of 0.0, the LOD score was −14.50 and, therefore, the hypothesis of tight linkage can be strongly rejected.
This report is the third study of the relationship between the insulin locus and MODY; however, it is the first report in which a formal linkage analysis indicates with a high degree of probability no linkage between the insulin locus and hypoinsulinemia in a family. Because MODY is a heterogeneous disorder, it may be that different genotypes result in a composite phenotype. The lack of linkage between an insulin allele and MODY in a total of four families studied, however, suggests that the insulin locus is probably not a marker for the MODY phenotype. These results do not exclude the possibility that the insulin locus may be involved in the etiology of other forms of NIDDM.
Metabolic and Therapeutic Assessment of Gestational Diabetes by Two-Hour and Twenty-Four-Hour Isocaloric Meal Tolerance Tests
Authors: Hollingsworth Dorothy Reycroft , Ney Denise , Stubblefield Nancy , Fell Tammy 
Published: September 2013

Lean and obese women with gestational diabetes (GDM) were given two different isocaloric meal challenge tests to assess glucose and insulin responses. Forty-three pregnant women received a 400-kcal isocaloric breakfast meal tolerance test (mini-MTT). Twenty of the subjects were also given a 2000-kcal isocaloric diet with three meals and three snacks during a 24-h period (maxi-MTT). This was the first study to utilize the physiologic challenge of mixed meals to compare insulin and glucose responses of both obese and lean normal pregnant women and women with GDM around the clock.
Normal obese pregnant women had higher integrated glucose and insulin values around the 24-h clock &lt; 0.003 and &lt; 0.03, respectively) than lean pregnant women. Lean and obese women with GDM also responded differently to the physiologic challenge of mixed meals. Some, but not all, obese diabetic subjects were markedly hyperinsulinemic in contrast to lean diabetic women who were relatively insulin deficient. One normoglycemic massively obese 18-yr-old pregnant woman was unexpectedly found to be severely hyperinsulinemic.
The two meal tolerance tests clearly defined a delay in the release of insulin in women with GDM (lean and obese) and markedly different quantitative insulin responses to identical meal challenges in obese diabetic subjects. Maternal hyperinsulinemia was positively correlated with prepregnancy body mass index (kg/m2) and heavier infants, but not with plasma glucose levels.
These studies provide evidence that GDM is a heterogeneous syndrome. Because of the variety of tests for GDM, the not unusual occurrence of carbohydrate intolerance in lean pregnant women without risk factors, and the worldwide differences in diagnostic criteria for this syndrome, we recommend screening for diabetes in all pregnant women. Finally, we have proposed that an extension of the National Diabetes Data Group classification be applied to pregnant women. In this scheme, gestational carbohydrate intolerance would be considered type III or GDM and be subdivided into nonobese and obese women. The increasing number of patients with carbohydrate intolerance secondary to renal dialysis, transplantation, cystic fibrosis, and other disorders might be called type IV or secondary diabetes.
Impaired Insulin Biosynthetic Capacity in a Rat Model for Non-insulin-dependent Diabetes: Studies with Dexamethasone
Authors: Giddings Stephen J , Orland Matthew J , Weir Gordon C , Bonner-Weir Susan , Permutt M Alan 
Published: September 2013

These studies of a rat model for non-insulin-dependent diabetes mellitus (NIDDM) were performed to determine whether hyperglycemia occurs when capacity to synthesize insulin is exceeded. The neonatal streptozocin (STZ)-treated rat has acute hyperglycemia with marked destruction of pancreatic β-cells, followed by gradual regeneration to 50–70% normal (β-cell number. At age 4 wk, fed serum glucose concentration is only mildly elevated relative to controls. With age, the rats become progressively hyperglycemic, and by 12 wk they have marked impairment of glucose-stimulated insulin release. In these studies, dexamethasone (0.125 mg/kg/day for 4 days) was administered to control and to STZ-treated animals to produce insulin resistance. The relationship between insulin biosynthesis and serum glucose concentrations was assessed. In control rats, response to dexamethasone was similar at both 4 and 12 wk. Serum glucose levels and pancreatic insulin concentration remained unchanged. Both insulin biosynthetic rates (as measured by 3Hleucine incorporation into proinsulin) and proinsulin mRNA levels increased twofold. STZ-treated rats at age 4 wk demonstrated mild hyperglycemia. Dexamethasone injection resulted in an increase in insulin biosynthesis and proinsulin mRNA in these animals, while serum glucose did not increase. STZ-treated rats at 12 wk showed more profound hyperglycemia (serum glucose 315 ± 38 mg/dl versus control, 187 ± 12 mg/dl). A marked rise in serum glucose (to 519 ± 42 mg/dl) was observed after4 days of dexamethasone injection. Pancreatic insulin content became severely depleted relative to salineinjected, STZ-treated animals, and there was no response of levels of proinsulin mRNA.
These studies demonstrate a significant correlation between mean insulin biosynthetic rates and mean proinsulin mRNA levels in 4-wk-old rats. In these rats with mild glucose intolerance related to a decrease in insulin synthesis, the rate of biosynthesis can still increase if demand for insulin is acutely increased by induction of an insulin-resistant state. If the correlation between proinsulin mRNA and biosynthesis exists in 12-wk-old animals, the data suggest that older, more hyperglycemic animals lose the capacity to increase rates of insulin biosynthesis and secretion; severe hyperglycemia ensues when capacity to synthesize insulin is exceeded.
Insulin Secretion In Vitro and Insulin Binding to Isolated Hepatocytes in Congenic Mice with Different H-2 Complexes
Authors: Petersen Karl-Georg , Heidenreich Stefan , Pilot Paul-Richard , Kerp Lothar 
Published: September 2013

Congenic male mice with differences in the H-2 complex have been used to investigate insulin secretion in vitro, insulin binding to isolated hepatocytes, plasma glucose, and serum insulin. Plasma glucose and serum insulin did not show consistent differences in the B10.BR, B10.D2, B10.A, B10.G, B10.M, B10.S, C57 10SCSN, and C3H.OH strains. Isolated islets of Langerhans responded to stimulation with 400 mg/dl glucose with a 3–5-fold increase in insulin secretion rates (2P &lt; 0.01): B10.BR &gt; B10.M &gt; C57BL/10SCSN &gt; B10.G &gt; C3H.OH, B10.D2, B10.A, B10.S. The biphasic pattern of insulin secretion was less distinct in B10.M, B10.G, and C3H.OH mice.
The high-affinity constants of insulin binding to isolated hepatocytes at 37°C varied between 4.5 × 10−7 L · mol−1 and 4.5 × 108 L · mol−1 (2P &lt; 0.01): B10.A &gt; B10.BR &gt; C57BL/10SCSN, B10.S, B10.D2 &gt; B10.M, B10.G.
The glucose-stimulated insulin secretion from isolated islets of Langerhans and the binding of insulin to isolated hepatocytes correlate to the H-2 complex independently.
Insulin's Effect on Leucine Turnover Changes During Early Fasting in the Conscious Dog
Authors: Hoxworth Ben , Miller Bonnie , Radosevich Paul , Buckspan Randy , Lacy William , Abumrad Naji N 
Published: September 2013

To study the effects of insulin on leucine turnover during fasting, acute insulin deficiency was induced by the simultaneous infusion of somatostatin and glucagon in conscious dogs fasted 18 h (N = 10) and 48 h (N = 11). Insulin levels during the basal period (before hormone perturbation) were similar in both groups of dogs (12 ± 3 versus 10 ± 3 μU/ml, respectively). Glucagon levels were similar in the two groups (94 ± 9 versus 106 ± 19 pg/ml). Leucine levels rose from 118 ± 9 jimol/L to 155 ± 12 fimol/L as fasting progressed (P &lt; 0.005). Its rate of appearance also increased by 30% (P &lt; 0.005) from 3.4 ± 0.3 to 4.3 ± 0.4 μmol/kg/min (P &lt; 0.005), while its clearance remained unchanged. Acute insulin deficiency caused an increase in leucine levels in both 18-h and 48-h-fasted dogs by 55% (to 181 ± 10 μnol/L) and 45% (to 225 ± 20 μmol/L), respectively (P &lt; 0.005). However, while the rate of appearance of leucine remained unchanged in dogs fasted overnight, it rose to 5.1 ± 0.3 μmol/kg/min (P &lt; 0.01) in those fasted 48 h. The metabolic clearance rate fell in both groups, although this drop was twice as great in the 18-h group (from 28 ± 3 to 17 ± 3 ml/kg/min, P &lt; 0.005) as in the 48-h group (from 28 ± 3 to 23 ± 2 ml/kg/min, P &lt; 0.005).
We conclude that insulin has disparate effects on protein turnover as fasting becomes more prolonged. Its acute absence results in enhanced proteolysis in the 2-day-fasted, but not in the overnight-fasted dog. These data suggest that the response of protein turnover to fasting is quite complex and involves more than the effects of changing insulin concentrations.
Skeletal Muscle Basement Membrane in Maturity-onset Diabetes in the Young
Authors: Mauer M , Steffes M , Johnson E , Rich S , Hoogwerf B , Chavers B , Barbosa J 
Published: September 2013

We have studied skeletal muscle capillary basement membrane width (CBMW) and intensity of skeletal muscle extracellular basement membrane staining for albumin and IgG in eight families with maturity-onset diabetes in the young (MODY).
Ninety-two MODY patients were identified. Sixtythree of these patients, 33 relatives with nondiagnostic oral glucose tolerance studies, and 61 normoglycemic relatives were studied for glucose and insulin. Twentysix of these MODY patients, 20 normoglycemic relatives, and 16 unrelated normal controls had skeletal muscle capillary morphologic studies.
The muscle capillary basement membrane was significantly increased in MODY patients younger than 40 yr when compared with unrelated normal subjects and relatives of the same age (P &lt; 0.001). However, in these families, the CBMW of MODY patients showed no significant thickening with age (slope = 0.45, P &lt; 0.14), as expected and seen in the normal subjects and in the normoglycemic relatives of the patients (slope = 1.21, P &lt; 0.001). The slope derived from the linear regression of age and CBMW in MODY patients (0.45 ± 0.29) was significantly less (P &lt; 0.05) than that of the nondiabetic subjects (1.21 ± 0.19). The mean intensity of skeletal muscle extracellular basement membrane staining for albumin was higher in MODY patients (1.1 ± 0.15) than in unrelated normal subjects (0.7 ± 0.1, P &lt; 0.025) and normal MODY family members (0.6 ± 0.08, P &lt; 0.01).
The unexpected absence of basement membrane thickening with age in the MODY patients may explain the paucity of vascular complications that have been reported by some. However, these findings may also reflect genetic heterogeneity, mild hyperglycemia, shorter duration of disease, or any combination of these factors. The immunohistochemical studies indicate that the increased localization of plasma proteins in extracellular membranes in diabetes, also seen in insulin-dependent diabetes, is a marker of hyperglycemia and is not specific for different types of diabetes.
Insulin-like Action of Proinsulin on Rat Liver Carbohydrate Metabolism In Vitro
Authors: Probst Irmelin , Hartmann Heinz , Jungermann Kurt , Creutzfeldt Werner 
Published: September 2013

Short-term effects of human proinsulin on metabolic rates and its long-term action on enzyme induction were studied in primary cultures of rat hepatocytes and in the perfused rat liver, and compared with the effects of bovine insulin. In the perfused rat liver, proinsulin decreased the glucagon-dependent increase of glycogenolysis. The action of 0.5 nM glucagon was almost completely suppressed by 100 nM proinsulin. Proinsulin and insulin showed similar potency.
In cultured rat hepatocytes, proinsulin stimulated glycolysis up to fivefold with a half-maximal effective dose of 30 nM. Proinsulin induced the key glycolytic enzymes glucokinase and pyruvate kinase by twofold and antagonized the glucagon-dependent induction of phosphoenolpyruvate carboxykinase with a halfmaximal effective dose at 3 nM. For the effects in cultured hepatocytes, about 100-fold higher concentrations of proinsulin than of insulin were required.
Aggregation of Insulin, Containing Surfactants, in Contact with Different Materials
Authors: Chawla Attar S , Hinberg Irwin , Blais Pierre , Johnson David 
Published: September 2013

The aggregation of insulin and of insulin protected with surfactants was studied by shaking at 37°C in glass, in polypropylene and polystyrene vials, and in CPI and Auto-Syringe insulin syringes and infusion sets. Surfactants such as Pluronic 17R8 and 25R5 hastened the aggregation, whereas Pluronic F68 was effective in preventing it. Furthermore, there was no change in the immunoreactivity of insulin containing Pluronic F68 even after 8 days of shaking. Unprotected insulin aggregated in all the vials.
There appears to be little problem with the commercial syringes tested, but the infusion sets could cause aggregation of insulin if used over an extended period of time. Although Pluronic F68 prevented insulin aggregation in situ, it extracted more impurities from the contacting plastics. Further development in materials and design of insulin sets and insulin containers appears necessary.
Nonenzymatic Glycation of Fibronectin and Alterations in the Molecular Association of Cell Matrix and Basement Membrane Components in Diabetes Mellitus
Authors: Tarsio Joseph F , Wigness Bruce , Rhode Thomas D , Rupp William M , Buchwald Hēnry , Furcht Leo T 
Published: September 2013

This study reports the nonenzymatic glycation of plasma fibronectin in vivo in diabetic dogs and also in vitro by incubation of human plasma fibronectin with excess glucose. Although no difference is observed in the total plasma fibronectin level, the nonenzymatic glycation of fibronectin is increased 2.3-fold in inbred male beagle dogs made diabetic with alloxan in comparison with age-matched controls. The extent of nonenzymatic glycation of fibronectin is shown to be proportional to blood glucose levels. HPLC reverse-phase analysis of the hydrolyzed amino acids and glycoamino acids from plasma fibronectin samples of normal and diabetic dogs show that nonenzymatic glycation occurs only on lysine residues.
When purified human plasma fibronectin was incubated in vitro with 500 mM glucose, the extent of nonenzymatic glycation of fibronectin was observed to increase proportionately with time. Ligand binding assays conducted in solution with varying concentrations of 3H-heparin in the presence of a constant amount of normal or nonenzymatically glycated human plasma fibronectin gave virtually identical binding curves. However, the binding of 3H-heparin to normal fibronectin could be increased fourfold by the concomitant addition of normal gelatin (denatured calfskin collagen). If in vitro glycated fibronectin and/or in vitro glycated gelatin are added under this latter condition with 3H-heparin, there is a tremendous decrease in the expected heparin binding seen with normal levels of nonenzymatic glycation. Other experiments were performed to quantitate the binding of 3H-labeled fibronectin to gelatin-coated nitrocellulose filters. Nonenzymatic glycation of fibronectin in vitro resulted in markedly decreased binding of 3H-fibronectin to collagen. Enhanced nonenzymatic glycation of fibronectin in vivo and alterations in the molecular association of fibronectin, gelatin, and heparin brought about by nonenzymatic glycation are discussed relevant to the pathophysiology of the complications of diabetes.
Products of Therapeutic Insulins in the Blood of Insulin-dependent (Type I) Diabetic Patients
Authors: Robbins David C , Shoelson Steven E , Tager Howard S , Mead Patricia M , Gaynor Deborah H 
Published: September 2013

The tendency of insulin in high concentrations to selfassociate and the widespread presence of insulindegrading enzymes suggest that fragments and/or aggregates of insulin may circulate in normal and insulin-dependent diabetic (IDOM) individuals. To examine this possibility, we have analyzed, by sensitive physicochemical methods, immunoreactive insulin (IRI) taken from the blood of 9 healthy volunteers and 12 insulin-dependent diabetic patients. IRI from the blood of the normal volunteers was composed of 6000 (91.0 ± 1.4%) and 9000 (9.0 ± 1.4%) molecular weight (mol wt) material. By 10% polyacrylamide disc gel electrophoresis (PAGE) and reverse-phase, high-performance liquid chromatography (HPLC), the 6000 mol wt material was indistinguishable from human insulin standards and insulin fragments were not found. C-peptide reactivity in the 9000 mol wt material confirmed the expected presence of proinsulin and intermediates of proinsulin conversion.
IRI harvested from the blood of 12 C-peptide-negative IDDMs, using a variety of insulin preparations, also separated into 6000 (80.5 ± 3.9%) and 9000–12,000 (19.5 ± 3.9%) mol wt material. By HPLC, 6000 mol wt IRI was either pork insulin (in volunteers using pure pork insulin) or a mixture of beef (∼90%), pork (∼10%) and deamidated beef (trace) insulin in those using a beef-pork mixture. However, the 9000–12,000 mol wt material had characteristics entirely distinct from proinsulin of either human or animal origin: (1) C-peptide reactivity was undetectable using any of three sensitive radioimmunoassay systems, (2) on PAGE it migrated more rapidly than proinsulin-like material, and (3) in contrast to proinsulin, it was unaffected by proteolytic degradation.
We conclude that a covalent aggregate of therapeutic insulin circulates in diabetic patients who use a variety of insulin preparations. Insulin aggregates may account for a relatively large amount of the total IRI in IDDMs, and these aggregates may promote the formation of anti-insulin antibodies and affect the action of insulin.
Glucose Toxicity for Human Endothelial Cells in Culture: Delayed Replication, Disturbed Cell Cycle, and Accelerated Death
Authors: Lorenzi Mara , Cagliero Enrico , Toledo Silva 
Published: September 2013

Functional and anatomical abnormalities of endothelium may represent a pathway to the increased vascular permeability and accelerated atherosclerosis characteristic of diabetes. To identify whether and how hyperglycemia may compromise the endothelial barrier, we have employed an in vitro system of human endothelial cells obtained from umbilical veins and cultured in elevated glucose concentrations (20 mM). Under these conditions, the achievement of saturation density was substantially delayed, with cell counts throughout most of the growth curve being 70–80% of control (P &lt; 0.002). More profound suppression of cell number was present in cultures exposed to 40 mM glucose. Similar, albeit slightly lesser, effects were observed in cultures exposed to 20 mM mannitol, mimicking the hypertonicity of the high glucose media. The effect of elevated glucose and mannitol was primarily mediated by a decrease in overall rate of replication of the endothelium as documented by the lower mitotic index (P &lt; 0.025).
Analysis of the distribution of cells along phases of the cell cycle uncovered in the high glucose cultures a decreased proportion of cells in G0-G1 (70.5 ± 5% versus 73.2 ± 4% in controls, P &lt; 0.05) and an increased proportion of cells in S phase (16.5 ± 2.7% versus 13.5 ± 2.2% in controls, P &lt; 0.01), suggesting that the replicative delay is likely to occur between the phase of DNA synthesis and mitosis. Increased cellular death was specifically observed in the cultures exposed to elevated glucose concentrations (P &lt; 0.05), but it could account for only a minor portion of the deficit in cell number.
The mechanism(s) underlying the described ill effects of high glucose/hypertonicity on endothelium and the relevance of such abnormalities to diabetic angiopathy are currently under investigation.
Abnormal Insulin Secretion in a Streptozocin Model of Diabetes: Effects of Insulin Treatment
Authors: Leahy J L , Bonner-Weir S , Weir G C 
Published: September 2013

We have proposed that chronic hyperglycemia causes the abnormal glucose influence on arginine-stimulated insulin secretion in the neonatal streptozocin (STZ) rat model of NIDDM and therefore studied the effect of 24h of mild insulin-induced hypoglycemia on this defect. Ultralente insulin, 20 U/kg, was given at 9 a.m. and 10 U/kg at 5 p.m., and insulin and glucagon secretion were then studied the next morning using the in vitro isolated, perfused pancreas. The fed plasma glucose concentrations decreased in the STZ rats from 191 ± 13 to 101 ± 9 mg/dl and from 133 ± 4 to 99 ± 8 mg/dl in the controls.
As expected, 10 mM arginine caused a trivial insulin response at 2.8 mM glucose in the treated and untreated control groups compared with the marked one at 16.7 mM. The response to arginine at 2.8 mM glucose in the untreated STZ rats, however, was strikingly elevated (7.65 ± 2.29 versus 0.41 ± 0.16 ng/ml in the untreated controls) and it was not potentiated by the high glucose background, but the result at 2.8 mM glucose in the treated STZ rats was similar to that of the treated controls (0.46 ± 0.12 versus 0.16 ± 0.03 ng/ml). A returh of glucose influence on IBMX-stimulated insulin secretion was also noted. Glucose-induced insulin release, however, was not restored in the treated STZ rats, but it was markedly suppressed in the controls by the insulin treatment.
Glucose influence on the glucagon response to arginine was maintained in the STZ model even though the glucagon release to a lowered glucose concentration was lost.
These data suggest that chronic hyperglycemia causes the abnormal glucose influence on argininestimulated insulin release in the STZ model of diabetes.