bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a High Voltage Technique to Determine the Molecular Requirements for Exocytosis in Islet Cells
Authors: Pace Caroline S , Tarvin John T , Neighbors Ann S , Pirkle James A , Greider Marie H 
Published: September 2013

SUMMARY
Pancreatic islet cells were subjected to high voltage discharges, which induced pore formation in the plasma membrane. This technique was used to determine the molecular requirements of intracellular sites involved in the control of insulin release in β-cells. Islets, preloaded with 86Rb+ and then shocked, released 92% of the radioisotope within 1 min as compared with only a 55% loss from nonshocked islets. Exposure of the islets to 14C-urea and 3H-sucrose at 0 to 10 min after exposure to high voltage discharges indicated that 68% of the intracellular space was occupied by sucrose, whereas sucrose was excluded from nonshocked islet cells. The pores in the plasma membrane resealed about 30 min after their initial formation, as was indicated by the cellular exclusion of sucrose.
The Ca++ concentrations yielding half-maximal and maximal secretory responses from shocked islets were 0.05 × 10−6 M and 0.35 × 10−6 M, respectively; the presence of 16.7 mM glucose did not alter these values. In intact islets, a variation of extracellular Ca++ (only in the presence of 16.7 mM glucose) generated a dose-response curve yielding half-maximal and maximal secretory responses at 2.0 × 10−3 M and 4.0 × 10−3 M, respectively. The total amount of insulin released from shocked islets was three times that released from nonshocked islets during a 15 min incubation period. The addition of 1 or 5 mM ATP during an initial shock and incubation period did not augment the secretory response to 0.05 × 10−6 M Ca++, but the presence of ATP was necessary, or the islets would not respond to 0.35 × 106 M Ca++ during a subsequent shock and incubation period. The presence of 1.0 mM 3-phosphoglycerate or phosphoenolpyruvate augmented the secretory response to 0.05 × 10−6 MCa++ only in the presence of 1.0 mM ATP. Glucose-6- phosphate or fructose-1,6-diphosphate had no influence on the secretory response to Ca++ in the presence of ATP. An increase in Mg++ from 1.0 to 10 mM reduced the secretory response to 0.35 × 10−6 M Ca++ by 63%. Islets, subjected to the high voltage discharges and allowed 30 min to reseal, exhibited a normal secretory response to 16.7 mM glucose. The results indicate that the high voltage technique induces reversible pore formation in β-cells to introduce ions and solutes into the intracellular environment so that the factors controlling exocytosis can be determined.
The Relationship of Intracytoplasmic Movement of Beta Granules to Insulin Release in Monolayer-cultured Pancreatic Beta-Cells
Authors: Kanazawa Yasunori , Kawazu Shoji , Ikeuchi Masatoshi , Kosaka Kinori 
Published: September 2013

To study the mechanism of insulin release, we examined β-granule movement in the cytoplasm of monolayer-cultured B-cells. The majority of the granules do not move, while about 2% of the granules moved per minute. The velocities of 90% of the moving granules exceeded 0.4 μm/s and showed saltatory type of movement. This movement may have a role in transport of the beta granule from Golgi to B-cell membrane.
We studied the mechanism of this movement using colchicine. Granule movement decreased exponentially by treatment with colchicine (10−6 M to 10−4 M). Almost 60 min was necessary to get a full inhibitory effect of colchicine on granule movement.
Colchicine (10−8 M to 10−4 M) inhibits insulin release in a dose-dependent manner. Maximum inhibition of insulin release (by about 40%) by colchicine (10−4 M) required 60 min. Granule movement also decreased when insulin release was inhibited by lowering glucose from 16.5 mM to 2.7 mM. Thus, granule movement participates in the mechanism of insulin release and may be related to the microtubular system.
Somatostatin Release from the Isolated, Perfused Diabetic Rat Pancreas: Inverse Relationship Between Pancreatic Somatostatin and Insulin
Authors: Kadowaki Seizo , Taminato Tomohiko , Chiba Tsutomu , Goto Yasuo , Nozawa Masumi , Seino Yutaka , Matsukura Shigeru , Fujita Takuo 
Published: September 2013

The changes in pancreatic somatostatin content and release were studied in streptozotocin (STZ)-diabetic rats. Male Wistar rats were treated with a graded dose of STZ (group I, 0; II, 25; III, 50; IV, 75 mgμkg), which produced various grades of diabetic rats four weeks later. The pancreatic somatostatin content increased in proportion to the dose of STZ (1,189 ± 31; II, 222 ± 20; III, 343 ± 4; IV, 515 ± 36 ngμg wet wt), while graded reductions of insulin content were observed. Significant increases in glucagon content were found only in groups III and IV. Pancreatic somatostatin release increased during arginine infusion (19.2 mM) dose dependently, (I, 543 ± 36; II, 946 ± 64; III, 1229 ± 55; IV, 2186 ± 150 pg/15 min), and it correlated with the graded decreases of insulin release. The glucagon release induced by arginine, however, did not change significantly.
These results indicate that pancreatic somatostatin content and release increased in STZ-diabetic rats in proportion to the degree of insulin deficiency.
Insulinopenic Diabetes After Rodenticide (Vacor) Ingestion: A Unique Model of Acquired Diabetes in Man
Authors: Karam John H , Lewitt Peter A , Young Clinton W , Nowlain Robert E , Frankel Barbara J , Fujiya Hiroshi , Freedman Zachary R , Grodsky Gerold M 
Published: September 2013

A clinical syndrome, characterized by acute diabetic ketoacidosis associated with a toxic neuropathy, developed in five men who intentionally ingested a recently introduced rodenticide (Vacor) containing N-3-pyridylmethyl-N'-p-nitrophenyl urea (RH-787). A 7-yr-old boy, who accidentally ingested this poison, died within 14 h.
Marked insulinopenia, without a reduction in glucagon levels, suggested a specific beta-cytotoxic effect, which was supported after autopsy in three cases by histopathologic evidence of extensive beta cell destruction. Lethal effects in rats prevented investigation of RH-787's diabetogenicity in vivo; however, studies in isolated rat islets confirmed a direct inhibitory effect, which was prevented by concomitant incubation with nicotinamide, suggesting a mechanism of action similar to that of streptozotocin.
We detected islet cell-surface antibodies in two of four patients studied.
These findings indicate that this nongenetic, acquired form of insulinopenic diabetes, which has persisted in the surviving patients for up to 3 yr, presents a unique opportunity to test in man the concept that hyperglycemia and the accompanying metabolic consequences of insulinopenia can induce diabetic microangiopathy in the absence of genetic predisposition.
Impaired Responses of Catecholamines, Growth Hormone, and Cortisol to Graded Exercise in Diabetic Autonomic Neuropathy
Authors: Hilsted Jannik , Galbo Henrik , Christensen Niels Juel 
Published: September 2013

Six juvenile diabetics [age, 31 ± 2 yr ( and SEM); duration of diabetes, 15 ± 4 yr], who showed signs of autonomic neuropathy (decreased beat-to-beat variation in heart rate during deep breathing), and seven control patients of similar age (27 ± 1 yr) and duration of diabetes (14 ± 2 yr) performed graded exercise on an ergometer cycle 3 h after breakfast and subcutaneous administration of insulin.
Plasma epinephrine increased significantly in both patient groups and was not significantly different at exhaustion [0.43 ± 0.17 ng/ml (neuropathy) vs. 1.07 ± 0.28 ng/ml (controls), P &lt; 0.1]. Plasma norepinephrine levels increased significantly in control patients but not in autonomic neuropathy, and they were significantly different at exhaustion [1.43 ± 0.34 ng/ml (neuropathy) vs. 2.51 ± 0.26 ng/ml (controls), P &lt; 0.05]. The relationships between plasma norepinephrine and epinephrine levels, respectively, and relative work load (expressed as oxygen uptake—in per cent—of individual maximal oxygen uptake) were shifted to the right in patients with autonomic neuropathy, indicating impaired sympathetic activity.
A significant decrease in plasma glucagon levels was found at low work loads (50 W and 75 W) in control patients but not in patients with autonomic neuropathy. At exhaustion, plasma glucagon levels were similar to resting levels in both patient groups. At exhaustion, plasma growth hormone and cortisol levels were significantly above preexercise levels only in control patients (50.5 ± 7.9 mU/L and 23.5 ± 2.9 ug/100 ml, respectively), and they were higher in these patients, P &lt; 0.025 and P &lt; 0.005, respectively, than in patients with autonomic neuropathy (24.4 ± 8.4 and 12.8 ± 1.6, respectively). Metabolic responses were similar in the two patient groups, as judged from plasma concentrations of glucose, lactate, free fatty acids, glycerol, and beta-hydroxybutyric acid.
In conclusion, diabetics with decreased beat-to-beat variation in heart rate displayed impaired responses of catecholamines, indicating a defective sympathoadrenal outflow, and of other glucoregulatory hormones during graded exercise.
Glucose and Insulin Responses to Oral Glucose in Overt Non-insulin-dependent Diabetics With and Without the Islet Cell Antibody
Authors: Gray R S , Irvine W J , Cameron E H D , Duncan L J P 
Published: September 2013

Plasma insulin, glucose, and insulin/glucose responses to a 50-g oral glucose tolerance test (OGTT) were compared in 14 islet cell antibody (ICAb) positive non-insulin-dependent diabetics (NIDDM), 14 matched ICAb negative NIDDM, and 14 ICAb negative nondiabetic controls. Both groups of NIDDM exhibited marked carbohydrate intolerance with insulinopenia. Despite having significantly higher plasma glucose concentrations during the study, the ICAb positive NIDDM had significantly lower insulin levels, and thus lower insulin/glucose ratios, than the ICAb negative NIDDM both in the fasting state and in response to the OGTT. Similarly, ICAb positive NIDDM had higher integrated glucose responses (ΔG), lower integrated insulin responses (ΔI), and lower (Δ/ΔG values than ICAb negative NIDDM. Three ICAb negative and seven ICAb positive NIDDM subsequently required insulin treatment.
These findings show that ICAb positive NIDDM suffer from a greater disturbance of B-cel1 function than do matched ICAb negative NIDDM.
Effects of Intraportal Islet Transplantation on the Transplanted Tissue and the Recipient Pancreas: I. Functional Studies
Authors: Trimble E R , Karakash C , Malaisse-Lagae F , Vassutine I , Orci L , Renold A E 
Published: September 2013

It is well known that, in diabetes, there is an abnormality of both pancreatic beta and alpha cell secretion. Since islet transplantation can markedly improve the diabetic state in streptozotocin-treated rats, we investigated the effects of intraportal transplantation on the beta and alpha cell secretion of the transplanted tissue. In addition we examined the effects of transplantation on the hormone content of both the transplanted tissue and the endogenous pancreas.
Animals were examined 6 and 20 wk after transplantation. Isolated perfusions of the islet-containing livers showed that both glucagon and insulin secretion could be promptly stimulated by arginine. The hormone content of the livers at death revealed that, while the insulin content of transplanted tissue was well maintained, there was a marked reduction in glucagon content. An increase in pancreatic glucagon content was found in rats with untreated diabetes of five months' duration; this was partially or fully prevented by islet transplantation. There was also a moderate increase in insulin content of the pancreases of animals that received islet transplants.
Effects of Therapy on the Nature and Quantity of Fuels Oxidized During Diabetic Ketoacidosis
Authors: Owen O E , Trapp V E , Reichard G A , Mozzoli M A , Smith R , Boden G 
Published: September 2013

We studied seven patients, in moderate to severe diabetic ketoacidosis (DKA), measuring respiratory exchanges of O2, GO2, and acetone and urinary excretion of nitrogen, ketone bodies, and glucose to calculate the respiratory quotient (RQ), nonprotein respiratory quotient (npRQ), metabolic requirements, and calories derived from fat, carbohydrate, and protein oxidation. Results from indirect calorimetry were related to circulating concentrations of glucose, free fatty acids, ketone bodies, and amino acids over a 14-h study consisting of a 2-h period I of rehydration with saline, a 4-h period II of rehydration and insulin therapy, and an 8-h period III of rehydration, insulin, and glucose administration.
During period I, of about 2 h of saline rehydration, the RQ (0.55–0.80) and npRQ (0.58–0.88) varied among the patients but in general was low. The caloric requirements were 1.24 kcal/min/1.73 m2. Initially,fat contributed 78 ± 11%, glucose 17 ± 10%, and protein 5 ± 2% of the metabolic requirements. The circulating concentrations of fuels remained constant. During period II, after about 4 h of saline and insulin therapy, the RQ (0.62–0.88) and npRQ (0.55–0.91) remained rather stable, rising in only two of seven patients. Nevertheless, in all patients, saline and insulin therapy was associated with precipitous decreases in circulating concentrations of glucose, free fatty acids, acetoacetate, and beta-hydroxybutyrate and gradual decreases in plasma amino acids. During period III, after 8–12 h of insulin therapy, the RQ (0.68–0.92) and npRQ (0.48–1.01) increased, rising in five of six patients. Heightened RQ and npRQ values were observed only after plasma free fatty acid concentrations decreased to 0.44 ± 0.12 mM and plasma acetoacetate plus beta-hydroxybutyrate concentrations decreased to 5.27 ± 1.86 mM, while plasma glucose concentration remained elevated at 13.49 ± 3.67 mM because of intravenous glucose infusion.
Caloric requirements diminished progressively throughout the study, and after about 4 h of saline and insulin therapy a reciprocal relationship between the contributions of fat and glucose to metabolic requirements was evident. At the end of period III the caloric requirements were 0.77 kcal/min/1.73 m2. Fat contributed 44 ± 16%, glucose 42 ± 22%, and protein 14 ± 8% of the metabolic requirements.
We have observed a dissociation between the decrease in plasma glucose, free fatty acids, ketone bodies, and amino acids and the nature of fuels oxidized. This suggests that, during the initial hours of therapy for DKA, the predominant effect of insulin is to promote fuel storage rather than to promote glucose and ketone body oxidation. It was 8–12 h in the course of therapy before the npRQ rose, reflecting heightened glucose oxidation and diminished fat oxidation. Metabolic requirements progressively decreased with therapy.
L-Asparaginase-induced Diabetes Mellitus in Rabbits
Authors: Lavine Robert L , Dicintio Deborah M 
Published: September 2013

Twenty-seven male New Zealand White rabbits were injected with a single dose of 10,000 IU E. coli L-asparaginase per kilogram body wt to document the diabetogenic activity of this antitumor agent. Significant weight loss was observed by day 1, and á loss continued until day 9. After day 16, weight steadily increased.
Random serum glucose levels increased steadily after the injection of L-asparaginase, reaching a peak value of 344 ± 32 mg/di ( ± SEM) on day 10. From day 12, levels declined, but they remained significantly higher than basal levels. Serum immunoreactive insulin (IRI) levels had a similar pattern of response. By day 2 the IRI was significantly above baseline. The IRI levels increased daily, reaching a peak level of 1379 ± 587 pg/ml ( ± SEM). Thereafter the levels fell gradually. However, the IRI levels remained significantly.higher than basal levels. Intravenous regular insulin decreased glucose levels in L-asparaginase–treated animals at 3 h by only 7.7 ± 3.2%, while it decreased them in controls by 34.0 ± 6.7% (P &lt; 0.0025).
These data demonstrate that, acutely, a single intravenous dose of 10,000 IU E. coli L-asparaginase per kilogram body wt induces a hyperinsulinemic, insulin-resistant, diabetic syndrome in rabbits.
Characterization of the Conversion of a Somatostatin Precursor to Somatostatin by Islet Secretory Granules
Authors: Fletcher Donald J , Noe Bryan D , Eric Bauer G , Quigley James P 
Published: September 2013

SUMMARY
The existence of a biosynthetic precursor for somatostatin has been previously demonstrated in angler-fish pancreatic islet tissue. In the present study, the subcellular conversion of this precursor to somatostatin was examined. When subcellular fractions were assayed for immunoreactive somatostatin, 86% of the immunoreactivity was found in the microsome and secretory granule fractions. Based on this finding and results from previous studies on proglucagon and proinsulin conversion, only these two fractions were examined for converting activity. After incubating islet tissue with [3H]tryptophan and [35S]cystine or [14C]iso-leucine for varying time periods, the tissue was fractionated and the microsome and granule fractions were subjected to postincubation. Conversion was monitored by the calculation of percent accumulation of somatostatin in eluates after Bio-Gel P-10 filtration of fraction extracts. Both secretory granules and microsomes converted endogenously labeled 8000–15,000-dalton precursor peptides to somatostatin. Disruption of the granules by repeated freeze-thawing or osmotic shock did not affect converting activity. Conversion of exogenously labeled precursors was also observed in both fractions. When granules were subjected to repeated freeze-thawing and high-speed centrifugation to separate membranes from sol, the membranes were found to have 29% more converting activity than the resulting supernates. Both membranous and soluble converting activities were significantly inhibited in the presence of leupeptin but not phenylmethyl sulfonyl fluoride. Significant inhibition of conversion was observed when lysed granules were postincubated in the presence of antipain, leupeptin, and p-chloromercuribenzoate but not chloroquine, di-isopropyl fluorophosphate, EDTA, or N-p-tosyl-L-lysine-chloromethyl ketone HCI. These results indicate that the prosomatostatin converting enzyme is a unique membrane-associated thiol proteinase with a possible specificity for arginine residues. The findings also indicate that the intracellular transport and processing of prosomatostatin is similar to that of other peptide hormone precursors.
Failure to Demonstrate Increased Protein Turnover and Intracellular Proteinase Activity in Livers of Mice with Streptozotocin-induced Diabetes
Authors: Bond Judith S 
Published: September 2013

SUMMARY
The effect of streptozotocin-induced diabetes on the turnover of acidic and basic mouse liver cytosol proteins was assessed. Previous work by others had demonstrated that acidic proteins are degraded more rapidly than basic proteins in livers of normal but not in severely diabetic animals. In this study, a milder form of diabetes was investigated to determine whether insulin-dependent diabetes in the absence of starvation, large weight losses, and impending death results in fundamental changes in degradation of the normally labile (acidic) proteins and stable (basic) proteins. The relative rates of degradation of liver proteins were measured by a double-isotope technique and by the loss of protein radiolabeled with [14C]-bi-carbonate. The relative rates of synthesis of proteins were estimated by incorporations of [3H]-leucine. No fundamental change in the relative rates of synthesis or degradation of acidic and basic proteins was observed. There was a general decrease in the incorporation of radiolabeled amino acids in the diabetic state and an increase in the specific activity of some amino acid–metabolizing enzymes, indicating changes in amino acid metabolism in liver. A study of the quantity and subcellular distribution of several liver cell proteinases revealed little if any changes in the proteolytic machinery of liver cells in this form of insulin-dependent diabetes. Thus, the fundamental changes in protein degradation seen in severe diabetes are not observed in a less severe form of the disease.
Complement-fixing Islet Cell Antibodies from Some Diabetic Patients Alter Insulin Release In Vitro
Authors: Sai P , Boitard Chr , Debray-Sachs M , Pouplard A , Assan R , Hamburger J 
Published: September 2013

To explore humoral immunity in insulin-dependent diabetic (IDDM) patients, we studied insulin release from isolated mouse islets stimulated by glucose + theophylline after incubation with the sera of these patients and complement. Eleven of 21 IDDM sera suppressed the stimulated insulin release while the arginine-stimulated glucagon release remained unchanged. Morphologic evidence and the trypan-blue exclusion test suggested that the suppression of insulin release was due to a cytotoxic effect of the sera.
No beta-cell inhibition or morphologic damage was detectable in the presence of sera from 30 healthy subjects, 8 non-insulin-dependent diabetic patients, and 5 nondiabetic patients with autoimmune diseases. Beta-cell inhibition by IDDM sera was not observed when complement was omitted. After serum fractionation, the cytotoxic potency of IDDM sera was located in the immunoglobulin G fraction. Using human islets, insulin release was suppressed by 3 of 6 IDDM sera.
Complement-dependent cytotoxicity was found in 1 of 5 recent-onset IDDM patients and 11 of 16 IDDM patients with autoimmune phenomena. It was associated in all cases with the presence of islet cell antibodies as detected by immunofluorescence, and with the presence of circulating lymphocytes which suppressed insulin release in vitro. Complement-fixing antibodies may contribute to the selective beta-cell damage in IDDM.
Long-term Continuous Intraperitoneal Insulin Infusion with an Implanted Remote-Controlled Insulin Infusion Device
Authors: Irsigler K , Kritz H , Hagmüller G , Franetzki M , Prestele K , Thurow H , Geisen K 
Published: September 2013

This is a report of the implantation and first 100-day operation using a remote-controlled programmable insulin infusion device in an insulin-dependent diabetic. To prevent insulin aggregation, a special surface-active polymer developed by Hoechst AG, Frankfurt, was used as an additive.
Implantation was completed on April 8,1981, and good metabolic control was reached immediately and has continued to date (July 1981), with this unit providing the only source of insulin. There have been no hypoglycemic attacks. Patient acceptance is very good. The Siemens unit, PFA 01 (external) and DFA 01 (implanted) has proved reliable and precise.
Prevention of Diabetic Nephropathy by Diet Control in the db/db Mouse
Authors: Lee Stanley M , Bressler Rubin 
Published: September 2013

Diabetes in the C57BL/KsJ(db/db) mouse is initially expressed as hyperinsulinemia, followed by hyperphagia, progressive obesity, and widespread pathologic abnormalities. This study was designed to evaluate the effects of metabolic control on the natural history of the diabetic nephropathy. Beginning at 1 mo of age and continuing for 12 wk, diabetic mice were subjected to controlled dietary restriction, such that their weight was maintained similar to that of age-matched, nondiabetic heterozygotes. Diet-restricted diabetics were compared with diabetics fed ad libitum and heterozygote nondiabetics.
Significant lowering of fasting blood glucose, water intake, and plasma insulin was achieved by diet restriction. The diet-restricted diabetics demonstrated enhanced metabolic efficiency, consuming approximately half as much food as the nondiabetics, while maintaining a similar weight.
Diabetics fed ad libitum evidenced well-defined renal lesions that included 3+ to 4+ immunoglobulin deposition in the glomerular mesangium, and generalized mesangial matrix expansion. These lesions were completely prevented in diet-restricted diabetics whose glomeruli were normal by light microscopy, and demonstrated trace to 1 + mesangial immunoglobulin deposition, features identical in all respects to the nondiabetics.
These results indicate that diabetic control achieved by prevention of obesity in the db/db mouse prevents the development of diabetic nephropathy.