bluuebunny/crossref_metadata_2025 huggingface dataset:
Fetal Pancreas Transplantation in Miniature Swine: II. Survival of Fetal Pig Pancreas Allografts Cultured at Room Temperature
Authors: Yoneda Kumiko , Mullen Yoko , Stein Elizabeth , Clare-Salzler Michael , Ozawa Akihito , Shevlin Linda , Danilovs John
Published: September 2013

Islet-allograft survival has been shown to be markedly prolonged in rodents when donor tissue has been precultured at 24°C. In this study, the feasibility of this approach was tested in NIH minipigs transplanted with fetal pancreases. Collagenase-digested fetal pig pancreatic tissues survived in culture at 24°C for 6–7 days and continued to grow in vitro at 37°C after being transferred. These tissues no longer stimulated allogeneic lymphocytes in vitro, although some tissues cultured at 37°C did. This allogeneic stimulation did not correlate to the number of major histocompatibility complex (MHC) class 11-positive cells in stimulator pancreatic cultures. When transplanted into an omentum pouch of normal, nonimmunosuppressed minipigs, fresh fetal pancreatic tissues were rejected within 14 days. Tissues cultured at 24°C grew, and β-cells proliferated in minipigs treated daily with cyclosporin A (CsA) and azathioprine. Twelve normal minipigs were transplanted with 24°C-cultured fetal pancreases: 8 pigs received no treatment, 2 received 14 mg · kg−1 · day−1 CsA for 14 days, and 2 received 6–7 intravenous injections of platelets prepared from pooled farm-pig blood before grafting. Strong lymphocytic infiltration was detected in all grafts removed between 30 and 90 days posttransplantation. However, β-cells were found on day 45 in one of five minipig pancreas grafts incompatible at the MHC loci and on days 60–90 in all three grafts compatible at MHC but incompatible at minor histocompatibility loci. Short-term CsA treatment did not prolong survival of allografts from farm pigs into minipigs. In contrast, some β-cells were detectable on day 30 in farm-pig pancreases grafted into 2 minipigs pretreated with platelets.
Metabolic Sequelae of Pancreas Transplantation
Authors: Paul Robertson R
Published: September 2013

Pancreas transplantation, when it is successful, achieves normal levels of fasting glucose and glycosylated hemoglobin (HbA1c) in recipients with type I (insulin-dependent) diabetes mellitus. However, many issues remain regarding the merits of this operative procedure. These issues include portal versus systemic pancreatic venous return, exocrine pancreas obstruction versus exocrine drainage of the allograft, metabolic consequences for donors of pancreas segments, criteria of effective hormonal secretion from fetal pancreas pieces and isolated islets, and adverse metabolic effects of immunosuppressive drugs. The future needs and directions of this research area include determination of the cause of excessive insulin levels and abnormal counterregulation of hypoglycemia in allograft recipients. Additionally, pancreatic polypeptide and somatostatin secretion are yet to be characterized. Finally, the long-term consequences of hemipancreatectomy in living related donors need to be established; specifically, whether donors are at increased risk for developing diabetes mellitus needs to be ascertained.
Fate of Late Complications in Type I Diabetic Patients After Successful Pancreas-Kidney Transplantation
Authors: Landgraf Rüdiger , Nusser Johann , Müller Wolfgang , Landgraf-Leurs Martina MC , Thurau Stefan , Ulbig Michael , Kampik Anselm , Lachenmayr Bernhard , Hillebrand Günther , Schleibner Stefan , Illner Wolf-Dieter , Abendroth Dietmar , Land Walter
Published: September 2013

The success rate of Pancreas transplantation allows us to study in more detail the potential beneficial effects of normoglycemia on secondary complications in diabetes mellitus. We report a prospective follow-up (mean 26 mo) of metabolic control, neuropathy, retinopathy, and peripheral microcirculation in 31 patients with type I (insulin-dependent) diabetes (mean age 33 ± 1 yr; mean duration of diabetes 21 ± 1 yr) after combined kidney and segmental pancreas grafting. All patients had normal HbA1 levels. Glucose tolerance (GT), insulin, C-peptide, and glucagon were normal in 22 patients, and impaired oral GT with reduced insulin secretory capacity was seen in 9 patients. During follow-up, there was no deterioration of GT and insulin release. Vascular risk factors, e.g., hypertension, cholesterol, and triglycerides, decreased after grafting. Autonomic neuropathy improved clinically, and R-R variation increased significantly in 3 of 18 patients. Peripheral neuropathy improved clinically in 46% of patients and did not deteriorate in the others. Motor nerve conduction velocity increased >20% in 8, <20% in 12, and was unchanged in 8 of 28 recipients. Most of the patients (n = 30) had pretransplant laser treatment of their advanced retinopathy. Posttransplant visual acuity improved at least more than one line in 56%, stabilized in 32%, and deteriorated in 12% of patients. Patients with functioning grafts for >1 yr had no further deterioration of visual acuity. Vitreous hemorrhage frequency and severity dropped markedly from pretransplant (from 69 to 24%) 10 mo after grafting. Retinal morphology remained stable in all eyes except two. Peripheral microcirculation judged by telethermography and transcutaneous oxygen pressure markedly increased 6 mo posttransplant. We conclude that pancreas-kidney transplantation may lead to an improvement in quality of life and that it may ameliorate or at least stabilize some of the far-advanced diabetic secondary complications.
Pancreas-Specific Protein New Serum Marker for Graft Rejection in Pancreas-Transplant Recipients
Authors: Fernstad Roland , Tydén Gunnar , Brattström Christina , Sköldefors Holger , Carlström Kjell , Groth Carl-Gustav , Pousette Åke
Published: September 2013

A radioimmunoassay for a novel human pancreatic protein (pancreas-specific protein, PASP) has been developed. We studied the possibility that serum PASP levels reflect pancreas-graft rejections in human pancreas-transplant recipients. Ten patients subjected to combined pancreas-kidney transplantation and 4 patients subjected to pancreas transplantation alone were studied. Twelve kidney recipients served as control subjects. On several occasions, PASP levels were elevated at kidney rejections in patients with combined pancreas-kidney grafts and then decreased after antirejection therapy, although no other indications for concomitant pancreas-graft rejection were at hand. In the recipients of pancreas grafts alone, PASP levels increased before or at the same time as graft rejections were indicated by current methods. In two cases of chronic graft rejection, PASP rose to high levels long before hyperglycemie occurred. In the control group of kidney-graft recipients, PASP levels were stable and were not affected by high serum creatinine levels, kidneyrejection episodes, or antirejection therapy. This study indicates that PASP may be a good serum marker for pancreas-graft rejection.
Early Detection of Rejection in Pancreas Transplantation
Authors: Stratta Robert J , Sollinger Hans W , Perlman Scott B , D'Alessandro Anthony M , Groshek Marilyn , Kalayoglu Munci , Pirsch John D , Belzer Folkert O
Published: September 2013

A major dilemma in pancreas transplantation is the lack of reliable methods for the early detection of allograft rejection. Over a 26-mo period, 70 rejection episodes occurred in 36 patients (13 isolated-pancreas, 23 simultaneous pancreas-kidney recipients) with pancreaticoduodenocystostomy. A total of 300 radionuclide pancreas examinations were performed (mean 8.3/patient) utilizing 99mTc-labeled DTPA. Computer analysis generated a quantitative measure of blood flow to the allograft (technetium index, TI). Rejection episodes were defined as isolated pancreas, isolated kidney, or combined pancreas-kidney. Mean urinary amylase (UA) levels and TI during normal allograft function were 30,256 U/L and 0.57%, respectively, whereas levels heralding rejection were 6873 U/L and 0.39% (P < .05). The treatment of rejection based on kidney dysfunction or combined pancreas-kidney dysfunction resulted in significantly higher graft salvage and a lower incidence of hyperglycemia compared with isolated-pancreas-allograft rejection. After therapy, a TI >0.3% was associated with 95.9% graft survival, whereas levels <0.3% resulted in a 72.7% rate of graft loss (P < .001). Similarly, pancreas allografts with a UA > 10,000 U/L had 92.2% functional survival, whereas levels < 10,000 U/L resulted in a 53.3% rate of graft loss (P < 0.001). Overall, reversal of rejection occurred in 80% of cases, with 10 pancreas and 2 kidney allografts lost due to rejection. Monitoring pancreas-allograft function by UA, TI, and renal function in simultaneous transplants allows for the timely diagnosis and successful treatment of pancreas-allograft rejection.
Long-Term Metabolic Control in Recipients of Segmental-Pancreas Grafts With Pancreaticoenterostomy or Duct Obstruction
Authors: Tydén Gunnar , Brattström Christina , Bolinder Jan , Bohman Sven-Olof , Groth Carl-Gustav , Björn Brekke Inge , Holdaas Hallvard , Flatmark Audun
Published: September 2013

Metabolic control in recipients of segmental-pancreas grafts with pancreaticoenterostomy (performed in Stockholm) or duct obstruction by polymer injection (performed in Oslo) were compared. The recipients were uremic diabetic patients and also received a kidney from the same donor. Because the patient population in the two Scandinavian countries is very similar and the immunosuppressive protocols used are almost identical, such a comparison seemed reasonable. The number of patients available for study at 1, 2, and 3 yr was 22, 10, and 4, respectively, with duct injection and 28, 10, and 3 with pancreaticoenterostomy. The mean age of the patients was somewhat higher in the Oslo series. There were no significant differences regarding immunosuppression or kidney-graft function as estimated by serum creatinine at 1, 2, and 3 yr. No significant differences were found in fasting blood glucose, glycosylated hemoglobin, and intravenous glucose tolerance between the two groups at 1, 2, and 3 yr.
Glucose Homeostasis and Insulin Secretion in Human Recipients of Pancreas Transplantation
Authors: Robertson R Paul , Abid Munir , Sutherland David ER , Diem Peter
Published: September 2013

To ascertain the consequences of pancreas transplantation with systemic venous drainage on glucose homeostasis and insulin secretion, glucose and insulin responses to intravenous glucose were compared in 10 recipients and 15 normal control subjects. There were no differences in fasting glucose levels or intravenous glucose disappearance rates. However, basal insulin levels and acute insulin responses to glucose were threefold greater in the recipients. It is not clear whether this consequence of hyperinsulinemia in the recipients is due to the abnormal circulatory drainage, the lack of autonomie input, or concurrent immunosuppressive drug therapy.
Whole-Plasma and High-Density Lipoprotein Subtraction Surface Lipid Composition in IDDM Men
Authors: Bagdade John D , Subbaiah Papasani V
Published: September 2013

To determine whether compositional abnormalities are present in high-density lipoprotein (HDL) in patients with insulin-dependent diabetes mellitus (IDOM) that might negate its putatively protective cardiovascular effects, we studied the plasma lipoproteins of 12 men with varying degrees of clinical control (mean fasting glucose 193 ± 10 mg/dl, mean glycoalbumin > 73% above control mean). The diabetic patients' basal plasma triglyceride, total- and free- (unesterified) cholesterol, HDL cholesterol (HDL-chol), and apolipoprotein Al, All, and B concentrations were similar to those of control subjects, but the freecholesterol- to-lecithin ratio, a new index of cardiovascular disease risk, was significantly increased in their plasma (0.97 ± 0.14 vs. 0.88 ± 0.07, P < .02) and their very-low-density lipoprotein (VLDL)-low-density lipoprotein (LDL) subfraction (1.50 ± 0.51 vs. 1.08 ± 0.15, P < .005). Although HDL2-chol was similar in diabetic and control groups, the HDL2-chol-to-free-cholesterol ratio (diabetic vs. control, 4.64 ± 1.7 vs. 1.96 ± 1.0 μmol/ml, P < .025) and the sphingomyelin-to-lecithin ratio (0.23 ± 0.08 vs. 0.20 ± 0.09, P < .025) were both significantly increased in the IDDM group. HDL3-chol was higher in the IDDM than in the control subjects (diabetic vs. control, 38.6 ± 5.2 vs. 32.7 ± 2.7 mg/dl, P < .005). In contrast to whole plasma and the VLDL + LDL subfraction, the freecholesterol- to-lecithin ratio of IDDM and control HDL subfractions were similar. These results demonstrate that men with IDDM have both qualitative and quantitative changes in lipoprotein surface lipid composition involving VLDL + LDL and HDL2 plasma subfractions. Because changes in the amounts of free cholesterol and phospholipid in lipoproteins have been shown to influence the directional fluxes of cholesterol, these compositional alterations suggest that IDDM may adversely affect both lipoproteinlipoprotein and lipoprotein-cell interactions.
Relationships Between Microvascular Function and Capillary Structure in Diabetic and Nondiabetic Human Skin
Authors: Katz Murray A , McCuskey Patricia , Beggs John L , Johnson Peter C , Gaines John A
Published: September 2013

Despite the commonly held view that abnormalities in capillary morphology, in particular thickening of the capillary basement membrane, are partly responsible for diabetic ischemia, few studies have correlated anatomic and hemodynamic variables in the same diabetic subjects. In a previous study of 24 type II (non-insulin-dependent) diabetic subjects and 24 agematched control subjects, we showed that a standard finger exercise vasodilated cutaneous forearm vessels nearly equally (51%), but the postarteriolar flow responded differently between groups. Nondiabetic subjects increased flow by recruitment of capillaries, whereas diabetic subjects did so by capillary flow augmentation. Moreover, resting permeability-surface area product (PS) to pentetic acid was 85% higher in diabetic than nondiabetic subjects. In this study, these same subjects had their forearm skin biopsied and examined morphometrically by electron microscopy for capillary radius, basement membrane thickness, endothelial cell density, and a folding index of luminal membrane reduplication. All morphological variables were correlated stepwise in a saturated, analysis of covariance model with the physiological results. The correlations were sparse and specifically excluded basement membrane thickness. The highest r2 value was .432 between resting PS and a ratio of capillary density to endothelial cell number per capillary. These studies show little evidence that diabetic microvascular physiological variables are tightly connected to morphometric changes except for minor permeability changes, which rise with capillary density and decrease with endothelial cell number. Because PS to pentetic acid is increased in diabetic subjects at any level of capillary density, it seems reasonable that permeability may be increased above that of nondiabetic subjects. However, such a conclusion is tentative because anatomic measurement of capillary density gives only the maximum estimate of capillaries in the tissue, which may be greater than the number of capillaries with flow at the time of physiological measurement.
Interleukin 1-Induced Prostaglandin E2 Accumulation by Isolated Pancreatic Islets
Authors: Hughes Jonathan H , Easom Richard A , Wolf Bryan A , Turk John , McDaniel Michael L
Published: September 2013

Recombinant human interleukin 1α (IL-1) has been found to induce prostaglandin E2 (PGE2) accumulation by isolated rat islets of Langerhans at concentrations similar to those at which the cytokine inhibits glucoseinduced insulin secretion and islet glucose oxidation. Maximal stimulation of PGE2 accumulation (5 times control value) occurred at 200 pM IL-1, and halfmaximal stimulation occurred at 25 pM IL-1. Significant augmentation of PGE2 accumulation by IL-1 required 10–18 h of exposure to the cytokine. Islets that had been pretreated with IL-1 for 18 h showed elevated rates of PGE2 production at basal (3-mM) and stimulatory (16.5-mM) glucose concentrations and converted exogenous arachidonic acid to PGE2 at twice the maximal rate of control islets. Exogenous PGE2 did not mimic the inhibitory effects of IL-1 on glucose-induced insulin secretion or glucose oxidation. To rule out the possibility that endogenous PGE2 is involved in the inhibitory effects of IL-1, the effect of a cyclooxygenase inhibitor on IL-1-treated islets was examined. Pharmacological blockade of PGE2 biosynthesis by 10 JAM indomethacin did not influence the inhibitory effects of IL-1 on glucoseinduced insulin secretion or glucose oxidation. Thus, exogenous PGE2 does not mimic the effects of IL-1 on islets, and inhibition of endogenous PGE2 biosynthesis does not suppress the effects of IL-1 on islets. These results suggest that PGE2 is not a principal mediator of the inhibitory effects of IL-1 on glucose-induced insulin secretion or glucose oxidation.
Elevated Proinsulin in Healthy Siblings of IDDM Patients Independent of HLA Identity
Authors: Hartling Svend G , Lindgren Fredrik , Dahlqvist Gisela , Persson Bengt , Binder Christian
Published: September 2013

Based on the recent demonstration of elevated serum proinsulin levels in cystic fibrosis patients with impaired glucose tolerance, it was hypothesized that proinsulin could be an indicator of altered β-cell function. We therefore analyzed fasting proinsulin levels in 99 siblings of insulin-dependent diabetes mellitus (IDDM) patients, most of them discordant for diabetes for >6 yr. The results from this group were compared with the results from 41 healthy age- and sex-matched control subjects with no family history of diabetes. Median (range) fasting proinsulin in siblings was 8.9 pM (1.7–58 pM) vs. 3.8 pM (<1.2–28 pM) in control subjects (P < .00001). There was no difference between the groups in fasting blood glucose concentrations. Both groups had fasting insulin concentrations within the normal range with a tendency toward lower values in the siblings: 108 pM (60–237 pM) vs. 118 pM (71–175 pM) (P = .07). The 99 siblings were subdivided into groups according to HLA sharing with their diabetic proband. The concentration of proinsulin, insulin, and blood glucose among the groups of 33 HLA-identical, 40 HLA-haploidentical, and 26 nonidentical siblings did not differ significantly. The fasting proinsulin level did not correlate with fasting levels of insulin, blood glucose, age, or body weight. We conclude that fasting proinsulin is elevated in healthy siblings of IDDM patients, whereas fasting insulin is normal or slightly decreased independent of HLA identity with their diabetic sibling. Elevated proinsulin levels could represent a family trait, perhaps mirroring a β-cell more vulnerable to destruction, or it could reflect previous β-cell damage that does not lead to IDDM.
Muscarinic Stimulation and Antagonism and Glucoregulation in Nondiabetic and Obese Hyperglycemic Mice
Authors: Fukudo Shin , Virnelli Suzanne , Kuhn Cynthia M , Cochrane Christina , Feinglos Mark N , Surwit Richard S
Published: September 2013

Plasma glucose and insulin responses to a muscarinic agonist (bethanechol chloride) and a muscarinic antagonist (atropine) were evaluated in obese C57BL/6J ob/ob mice and in lean C57BL/6J + /? mice. In lean + /? mice, plasma glucose decreased in response to 1 and 2 μg/g bethanechol chloride, whereas insulin increased significantly. In ob/ob mice, insulin increased remarkably in response to bethanechol administration (saline, 632 ± 80 μU/ml; 2 μg/g bethanechol chloride, 1794 ± 97 μU/ml; n = 10), but surprisingly, plasma glucose also rose significantly (saline, 230 ± 14 mg/dl; 2 μg/g bethanechol chloride, 363 ± 18 mg/dl, n = 10). This exaggerated hyperglycemie in ob/ob mice was not associated with significant changes in plasma glucagon. Furthermore, administration of propranolol hydrochloride did not diminish bethanechol chloride-induced hyperglycemia in ob/ob mice. Administration of atropine (2.5, 5, and 10 mg/kg body wt) induced a significant decrease in plasma insulin without changes in plasma glucose in ob/ob mice, whereas neither plasma insulin nor plasma glucose changed in lean mice. Finally, conversion of [14C]alanine to glucose was increased in ob/ob mice after bethanechol chloride administration, indicating that muscarinic stimulation increases gluconeogenesis in an animal model of type II (non-insulin-dependent) diabetes.
Myocyte Contracture, Vascular Resistance, and Vascular Permeability After Global Ischemia in Isolated Hearts From Alloxan-Induced Diabetic Rabbits
Authors: Tilton Ronald G , Daugherty Alan , Sutera Salvatore P , Larson Kenneth B , Land Marishawn P , Rateri Debra L , Kilo Charles , Williamson Joseph R
Published: September 2013

Coronary vascular hemodynamics, albumin permeation, and myocyte contractility were assessed in isolated hearts from 6-mo alloxan-induced diabetic (ALX-D) rabbits during 3 h of reperfusion after 40 min of global no-flow ischemia. Residue-detection data, generated during the single passage of a bolus of 125I-labeled bovine serum albumin (125I-BSA) through the coronary vasculature, were used to estimate indices of vascular function, including the mean transit time of 125I-BSA, the fractional rate of intravascular clearance of 125I-BSA, and 125I-BSA permeation of coronary vessels. During reflow after ischemia in hearts from control rabbits, vascular resistance increased approximately three times that at baseline, left ventricular end-diastolic pressure (LVEDP) increased 8–10 times, and maximum +dP/dt recovered 0.4 times baseline, whereas the fractional rate of washout of intravascular 125I-BSA decreased to less than one-half of baseline values (was prolonged 2-fold), and albumin permeation and mean-transit time were increased 3 and 5 times baseline, respectively. In hearts from diabetic rabbits, vascular resistance was similar to the control group before ischemia but increased only one-third as much during reflow after ischemia. Increases in LVEDP during reflow were ∼50% lower than controls, and +dP/df recovered ∼2.5 times more than in control hearts. 125I-BSA permeation in diabetics was similar to controls before ischemia, but during reflow increased 6 times (∼2 times controls). Washout of intravascular 125I-BSA was prolonged ∼20% versus baseline during 3 h of reflow in hearts from diabetic rabbits. Thus, ALX-D in the rabbit delayed ischemia-reperfusion injury to myocytes and vascular smooth muscle cells while increasing vascular albumin permeation.
Prostacyclin and Pathogenesis of Hemodynamic Abnormalities of Diabetic Ketoacidosis in Rats
Authors: Quyyumi Arshed A , Iaffaldano Robert , Guerrero J Luis , Ryan Colleen A , Powell William John , Axelrod Lloyd
Published: September 2013

The pathogenesis of the hemodynamic abnormalities of diabetic ketoacidosis (DKA) is not well understood. Previous studies suggest that prostacyclin (PGI2) production by adipose tissue is increased in DKA. We investigated the role of PGI2 in the pathogenesis of the reduced vascular resistance in DKA. Rats with streptozocin-induced DKA were anesthetized with pentobarbital sodium, and flow was measured with an electromagnetic probe on the infradiaphragmatic aorta The plasma level of 6-keto-PGF1α (stable derivative of PGI2) was higher (mean ± SE 0.91 ± 0.05 ng/ml) and vascular resistance lower (4.9 ± 0.2 mmHg · ml−1 · min−1 · 100 g−1 [resistance units, RU]) in 67 rats with DKA than in 21 normal rats (0.34 ± 0.03 ng/ml, P < .01, and 9.0 ± 0.7 RU, P < .01, respectively). Inhibition of cyclooxygenase activity with either indomethacin or meclofenamic acid reduced the plasma 6-keto-PGF1α level but failed to raise vascular resistance. Infusions of PGI2 in rats with DKA demonstrated that the vasculature was responsive to PGI2. Inhibition of cyclooxygenase activity not only reduced PGI2 production but also suppressed renin release. When the effects of the renin-angiotensin system were excluded by bilateral nephrectomy, indomethacin caused a significant increase (P < .05) in vascular resistance. Thus, the failure of cyclooxygenase inhibitors to raise vascular resistance in DKA was a result of concurrent suppression of vasodilator (PGI2) and vasoconstrictor (renin-angiotensin system) mechanisms that are activated in DKA. Insulin administration increased vascular resistance (P < .01) and decreased the level of plasma 6-keto-PGF1α (P < .01). Combined administration of PGI2 and insulin did not alter vascular resistance, suggesting that the increase in vascular resistance with insulin was predominantly due to the reduction of circulating PGI2. Thus, vascular resistance is decreased in DKA primarily as a result of the vasodilator effects of PGI2 produced by adipose tissue. The activation of the renin-angiotensin system represents a partial compensation. The increase in PGI2 production may contribute to the hypotension and mortality of DKA.
Importance of Small Intestine in Diabetic Hypercholesterolemia
Authors: Feingold Kenneth R
Published: September 2013

Numerous studies have demonstrated that poor glycemic control is asssociated with elevated plasma cholesterol levels in diabetic patients. Experiments have shown that cholesterol synthesis is increased in the small intestine of various diabetic animals. This increase is a generalized phenomenon occurring in all segments of the small intestine. Insulin therapy that normalizes blood glucose levels markedly decreases intestinal cholesterol synthesis in diabetic animals to a level similar to that observed in control animals. Studies have suggested that the hyperphagia that accompanies poorly controlled diabetes is the chief stimulus for the increase in intestinal cholesterol synthesis. However, the direct contact of the intestinal mucosa with nutrients is not the sole trigger for increasing cholesterol synthesis in the small intestine, suggesting that circulating and/or neurological factors play a role. The transport of newly synthesized cholesterol, most of which is in the chylomicron lipoprotein fraction, from the intestines to the circulation is increasedin diabetic rats. The sterols associated with these chylomicrons are rapidly cleared from the circulation and delivered to the liver. The increased transport of chylomicrons from the intestine to the circulation in diabetic patients could potentially result in several alterations in lipid metabolism that may increase the risk of atherosclerotic vascular disease.
Dimethyl Sulfoxide Modulation of Diabetes Onset in NOD Mice
Authors: Klandorf Hillar , Chirra Annapoorna R , Degruccio Andrew , Girman Derek J
Published: September 2013

Dimethyl sulfoxide (DMSO), a hydroxyl radical scavenger, is known as an immunosuppressive agent and can reduce autoantibody levels in experimental autoimmune diseases. Because classic diabetogens damage the DNA and membrane of the β-cell by the generation of free radicals, the purpose of these investigations was to determine whether the intake of DMSO or its derivatives methylsulfonylmethane (MSM) and dimethylsulfide (DMS) could prevent the expression of autoimmune diabetes in the spontaneously diabetic NOD mouse. DMSO (2.5%), MSM (2.5%), and DMS (0.25%) were added to the drinking water of female NOD mice immediately after weaning. Control animals were maintained on regular drinking water. The presence of overt diabetes was monitored from the age of 2 mo by weekly urinary glucose testing until the animals either became overtly glucosuric or were >240 days of age. In contrast to what we expected, DMSO (2.5%) markedly increased the rate at which the animals expressed overt diabetes (P < .0004, log-rank test). MSM had no effect, whereas DMS reduced the incidence and rate of diabetes onset. When DMSO (2.5%) was administered to male NOD mice and control strains of mice (BALB/c and ICR), the control group did not develop glucosuria or insulitis, whereas DMSO increased the incidence of diabetes in the male NOD mice from 21 to 79%. In contrast, when DMSO was fed to female NOD mice on a purified AIN-76 diet, diabetes onset was reduced to 36%. We conclude that DMSO accelerates the uptake of dietary diabetogens into the β-cell of genetically susceptible animals (NOD mice). The protective effect of the purified diet in such animals may be due to a lack of putative diabetogens in purified diet, or alternatively, the diet itself contains factor(s) that protect the β-cell from autoimmune attack and/or destruction.
Interleukin 2 and Soluble Interleukin 2–Receptor Secretion Defect In Vitro in Newly Diagnosed Type I Diabetic Patients
Authors: Giordano Carla , Pantò Felicia , Caruso Calogero , Modica Maria A , Zambito Anna M , Sapienza Nunzia , Amato Maria P , Galluzzo Aldo
Published: September 2013

In this study, we investigated whether an interleukin 2 (IL-2) secretion defect by peripheral blood mononuclear cells (PBMCs) after in vitro stimulation with phytohemagglutinin (PHA-M) occurs in either newly diagnosed or long-standing type I (insulin-dependent) diabetic patients and whether it is accompanied by a dysregulation of soluble IL-2— receptor (IL-2RS) production. PBMC cultures (2.5 × 106 cells), unstimulated or stimulated with PHA-M (25 μg/ml), from 20 type I diabetic patients (10 with time since onset <3 mo and 10 with long-term diabetes of <3 yr) and 10 control subjects were studied for the production of IL-2 and IL-2RS in their respective supernatants. No difference was found in IL-2 production in unstimulated cultures of type I patients compared with control subjects, although a significant decrease from PHA-M-stimulated cultures was seen (newly diagnosed, 1.7 ± 0.3 ng/2.5 × 106 cells; longstanding, 2.2 ± 0.3 ng/2.5 × 106 cells; P < .001 and P < .05, respectively) compared with control subjects (3.6 ± 0.4 ng/2.5 × 106 cells). In regard to the production of IL-2RS, no difference exists for unstimulated cultures, whereas, after PHA-M stimulation, both newly diagnosed and long-term-diabetic patients showed a decrease in the IL-2RS levels (318 ± 50 and 331 ± 62 U/2.5×106 cells; P < .02 and P < .05, respectively) compared with normal subjects (463 ± 34.2 U/2.5×106 cells). Thymus-activated cell phenotypes confirmed the T-lymphocyte activation after a 48-h culture period. The hypoproduction of IL-2 and IL-2RS in newly diagnosed patients may be the expression of the involvement of T-lymphocytes that have been activated continuously in vivo, but its presence in long-term patients suggests that the immunogenetic profile of the disease, involving immune-response genes also deputed to the control of lymphokine production levels, is such that type I diabetic patients are to be considered low IL-2 producers.
Insulin Depolarization of Skeletal Muscle in Absence of External Na+
Authors: Wu Fong-Sen , Rogus Ellen , Zierler Kenneth
Published: September 2013

Three mechanisms have been proposed by which insulin might increase the electrical potential difference across the cell membrane of some of its main target cells: stimulation of an electrogenic pump; increased permeability to K+ (PK); and decreased ratio of permeability to Na+ (PNa) compared to PK, with an absolute decrease in permeability to both ions. Our laboratory has reported that insulin-induced hyperpolarization (IIH) of rat skeletal muscle is not due to stimulation of a ouabain-inhibitable pump and that insulin decreases 42 K efflux, apparently eliminating the first two candidate mechanisms. If the remaining hypothesis is correct, when Na+ is removed from the bathing solution, insulin should depolarize, not hyperpolarize. It did. With Tris or N-methyl-D-glucamine substituted for Na+ , insulin depolarized by ∼3 mV. Ouabain had no effect. PNa decreased by >90%; PK was reduced by <40%. The main component of the immediate mechanism of IIH is the near elimination of PNa. Furthermore, when a poorly permeable cation was substituted for Na+, muscles hyperpolarized in the absence of insulin. This gave us an opportunity to test the hypothesis that hyperpolarization is a link in the insulin-transduction chain. Consistent with this hypothesis, rat muscles hyperpolarized in this manner in the absence of insulin took up more glucose than paired controls in normal Na+ solution.
Mechanism of Defective Insulin-Receptor Kinase Activity in NIDDM: Evidence for Two Receptor Populations
Authors: Brillon David J , Freidenberg Gary R , Henry Robert R , Olefsky Jerrold M
Published: September 2013

We used anti-insulin-receptor and anti-phosphotyrosine antibodies to elucidate the mechanism of decreased insulin-receptor tyrosine kinase activity observed in subjects with non-insulin-dependent diabetes mellitus (NIDDM). Lectin-purified insulin receptors were labeled with 125I-labeled NAPA-DP-insulin and autophosphorylated in the presence of 500 μM unlabeled ATP. Immunoprecipitation occurred in 43 ± 8% of the autophosphorylated, 125I-labeled receptors from nondiabetic subjects with anti-phosphotyrosine antibodies in contrast to 100% immunoprecipitation with anti-insulin-receptor antibodies. Anti-phosphotyrosine antibodies immunoprecipitated only 14 ± 6% of NIDDM receptors (P < .05 vs. nondiabetic receptors). A significant correlation existed between maximal insulin-stimulated receptor tyrosine kinase activity and the proportion of receptors immunoprecipitated by anti-phosphotyrosine antibodies (r = .76, P < .01). These results suggest that human adipocytes contain two distinct receptor populations, both of which bind insulin but only one of which is capable of insulin-stimulated tyrosine phosphorylation. In nondiabetic subjects, 40–50% of the receptors that bind insulin are capable of insulin-stimulated tyrosine autophosphorylation. The proportion of receptors that bind insulin but are incapable of insulin-stimulated tyrosine autophosphorylation is increased in NIDDM; the magnitude of this increase correlated with the magnitude of the decrease in kinase activity.
Decreased Sympathochromaffin Activity in IDDM
Authors: Cryer Philip E
Published: September 2013

Catecholamines released from the sympathochromaffin system produce metabolic changes similar to those of diabetes mellitus. However, increased sympathochromaffin activity does not appear to be a feature of insulin-dependent diabetes mellitus (IDDM), although physiologic catecholamine increments may contribute to short-term metabolic derangements under some conditions. Increased glycemic sensitivity to epinephrine is a feature of IDDM but is the result of the inability to secrete insulin rather than of increased cellular sensitivity to catecholamines. Absolute insulin deficiency results in increased metabolic (glycemic, lipolytic, and ketogenic) sensitivity to catecholamines. More generalized hypersensitivity occurs in diabetic autonomic neuropathy. However, the clinical relevance of these alterations in sensitivity remains to be established. On the other hand, decreased sympathochromaffin activity is common and causes considerable morbidity and some mortality in people with diabetes. In addition to increased sensitivity to catecholamines, decreased sympathochromaffin activity results in the clinical syndromes of postural hypotension, hypoglycemia unawareness, defective glucose counterregulation, or a combination of these. The latter two syndromes cause an increased frequency of severe iatrogenic hypoglycemia, at least during intensive therapy of IDDM. Thus, decreased rather than increased sympathochromaffin activity often complicates IDDM. Clearly, ways to prevent, correct, or compensate for this component of diabetic autonomic neuropathy must be learned before diabetes can be managed effectively and safely in all patients who suffer from the disease until diabetes mellitus is eradicated.
Effect of d-Fenfluramine on Basal Glucose Turnover and Fat-Feeding-Induced Insulin Resistance in Rats
Authors: Storlien Leonard H , Thorburn Anne W , Smythe George A , Jenkins Arthur B , Chisholm Donald J , Kraegen Edward W
Published: September 2013

There is evidence that fenfluramine improves insulin action independently of its anorectic and weight-loss-inducing properties. Chronic d-fenfluramine also reduces hypothalamic noradrenergic tone, which correlates highly with hepatic glucose output. We report that chronic d-fenfluramine (5 mg · kg−1 · day−1) ameliorates insulin resistance induced by high-fat feeding. Insulin action was assessed in adult male rats at basal insulin levels and at hyperinsulinemia (∼140 mU/L with the euglycemic clamp technique). Hepatic glucose production, peripheral glucose disposal, and individual tissue glucose metabolism were determined from bolus injections of [3 H]-2-deoxyglucose and [14 C]glucose. Food intake was matched between groups. Basal glucose turnover was reduced 28% (P < .05) in fat-fed rats receiving d-fenfluramine (fat+fen). The glucose infusion rate to maintain euglycemia was 22.0 ± 1.1 mg · kg−1 · min−1 in the high-carbohydrate-fed rats, 8.2 ± 1.0 in fat-fed rats, and 15.1 ± 0.5 in the fat + fen group. Peripheral glucose disposal, reflecting measured skeletal muscle changes, was reduced by fat feeding (from 23.5 ± 1.0 to 13.8 ± 0.6 mg · kg1 · min−1) but was improved by d-fenfluramine (16.9 plusmn; 0.5, P < .05 vs. fat fed). Impaired suppression of hepatic glucose output by insulin, caused by fat feeding, was totally reversed by d-fenfluramine. Thus, d-fenfluramine counteracted diet-induced insulin resistance, with the predominant effect on the liver. We hypothesize that d-fenfluramine improves insulin action by reducing hypothalamic noradrenergic tone, which in turn reduces the neural drive to hepatic glucose output and improves the hepatic response to insulin.
Omega-3 Fatty Acids in Diabetes Mellitus: Gift from the Sea?
Authors: Axelrod Lloyd
Published: September 2013

The potential role of omega-3 fatty acids in the prevention of atherosclerotic disease in the nondiabetic population currently engenders interest, enthusiasm, and controversy. Some apparently beneficial effects of omega-3 fatty acids on platelet function, eicosanoid formation, plasma triglyceride levels, and blood pressure have been described in patients with diabetes mellitus. However, enthusiasm for the use of omega-3 fatty acids in diabetes has been dampened by reports of potentially deleterious effects of these agents, including increased plasma glucose, glycosylated hemoglobin, plasma total cholesterol and LDL cholesterol, and serum apolipoprotein B levels. These adverse effects have been achieved with large, perhaps excessive, doses of omega-3 fatty acids, in the range of 4–10 g/day. The magnitude of these adverse effects has been small (typically 10–36%). It cannot be assumed that the effects of omega-3 fatty acids are the same in patients with diabetes mellitus as in nondiabetic subjects or patients with primary hyperlipidemia. First, the biosynthesis and composition of fatty acids is abnormal in diabetic animals and possibly in diabetic patients. Second, many potential mechanisms implicated in the pathogenesis of atherosclerosis are present in diabetic but not necessarily in nondiabetic subjects. Third, the mechanisms of many of the risk factors in diabetic patients differ from the mechanisms of these abnormalities in nondiabetic subjects, reflecting the effects of insulin deficiency, hyperglycemia, and their sequelae. Finally, because diabetes is a heterogeneous group of diseases, the effects of omega-3 fatty acids must be addressed separately for patients with insulindependent diabetes mellitus, non-insulin-dependent diabetes mellitus, and possibly other forms of diabetes. Thus, it is not possible to assess thepotential risks and benefits of dietary fish and fish oils in diabetic patients. Studies are needed to determine the regulation of fatty acid synthesis and the fatty acid composition of phospholipids in diabetic patients under defined conditions of metabolic control and diet and to determine the effects of dietary fish and fish oils in appropriate quantities on the fatty acid composition of phospholipids, the mechanisms involved in the pathogenesis of vascular disease in diabetes, and the incidence of microvascular and atherosclerotic complications.
Insulin and Ribosomal Protein S6 Kinase in Rat Pancreatic Acini
Authors: Sung Chin K , Williams John A
Published: September 2013

Treatment of pancreatic acini from diabetic rats with insulin resulted in a dose-dependent increase in the phosphorylation of ribosomal protein S6 when analyzed by two-dimensional gel electrophoresis. To study the presence of the protein kinase mediating this phosphorylation, soluble extracts of intact acini that had been previously treated with insulin were prepared and assayed for protein kinase activity with rat pancreatic ribosomes as a substrate. Activation of S6 kinase activity, observed in a time-dependent manner, was maximal after 20–30 min and, in a dose-dependent manner, was half-maximal at 1 nM and maximal at 10 nM insulin concentration. Based on cofactor requirements, substrate specificity, and a slow activation of the enzyme, the S6 kinase was distinct from cAMP-dependent, Ca2+-calmodulin-dependent, and Ca2+-phospholipid-dependent protein kinases and protease-activated kinase II. The S6 kinase activated by insulin was highly specific for the ribosomal protein S6 when compared with various substrates, including casein, glycogen synthase, phosphorylase b, phosvitin, histone HIII-S, and histone HVIII-S. Protein S6 phosphorylation in intact acini and activation of the S6 kinase by insulin showed similar dose-response curves, consistent with the S6 kinase being responsible for the protein S6 phosphorylation in intact acini. The comparison of the dose-response curves for S6 phosphorylation and protein synthesis in acini suggests that there is a close correlation between these two insulin actions.
Predominant Role of Gluconeogenesis in Increased Hepatic Glucose Production in NIDDM
Authors: Consoli Agostino , Nurjhan Nurjahan , Capani Fabio , Gerich John
Published: September 2013

Excessive hepatic glucose output is an important factor in the fasting hyperglycemia of non-insulindependent diabetes mellitus (NIDDM). To determine the relative contributions of gluconeogenesis and glycogenolysis in a quantitative manner, we applied a new isotopic approach, using infusions of [6-3H]glucose and [2-14C]acetate to trace overall hepatic glucose output and phosphoenolpyruvate gluconeogenesis in 14 postabsorptive NIDDM subjects and in 9 nondiabetic volunteers of similar age and weight. Overall hepatic glucose output was increased nearly twofold in the NIDDM subjects (22.7 ± 1.0 vs. 12.0 ± 0.6 μmol · kg−1 · min−1 in the nondiabetic volunteers, P < .001); phosphoenolpyruvate gluconeogenesis was increased more than threefold in the NIDDM subjects (12.7 ± 1.4 vs. 3.6 ± 0.4 μmol kg−1 min−1 in the nondiabetic subjects, P < .001) and was accompanied by increased plasma lactate, alanine, and glucagon concentrations (all P < .05). The increased phosphoenolpyruvate gluconeogenesis accounted for 89 ± 6% of the increase in overall hepatic glucose output in the NIDDM subjects and was significantly correlated with the fasting plasma glucose concentrations (r = .67, P < .01). Glycogenolysis, calculated as the difference between overall hepatic glucose output and phosphoenolpyruvate gluconeogenesis, was not significantly different in the NIDDM subjects (9.9 ± 0.06 μmol · kg−1 · min−1) and the nondiabetic volunteers (8.4 ± 0.3 μmol kg−1 · min−1). We conclude that increased gluconeogenesis is the predominant mechanism responsible for increased hepatic glucose output in NIDDM.
Inhibition of Streptozocin-Induced Insulitis and Diabetes With Lobenzarit in CD-1 Mice
Authors: Iwakiri Ryuichi , Nagafuchi Seiho
Published: September 2013

When multiple low doses (30 mg/kg body wt) of streptozocin were given to CD-1 mice, diabetes associated with L3T4 T-lymphocyte- and B-lymphocyte-predominant insulitis occurred. Thus, a model of type I (insulin-dependent) diabetes was obtained. To treat these diabetic mice, we administered lobenzarit (CCA), a newly synthesized immunomodulator. CCA (2 or 10 mg/kg body wt) significantly inhibited the progression of diabetes by suppressing the severity and incidence of insulitis. Insulin contents of the pancreas were preserved. The possibility that autoimmune-related diabetes can be treated with CCA warrants further attention.
Increased β-Cell Secretory Capacity as Mechanism for Islet Adaptation to Nicotinic Acid-Induced Insulin Resistance
Authors: Kahn Steven E , Beard James C , Schwartz Michael W , Ward W Kenneth , Ding Han Lun , Bergman Richard N , Taborsky Gerald J , Porte Daniel
Published: September 2013

To determine whether prolonged nicotinic acid (NA) administration produces insulin resistance and, if so, how the normal pancreatic islet adapts to prolonged insulin resistance, we administered incremental doses of NA to 11 normal men for 2 wk, ending at 2 g/day. Insulin sensitivity was measured with Bergman's minimal model. Islet function was evaluated by measurement of acute insulin (AIR) and glucagon (AGR) responses to arginine at three glucose levels. Insulin resistance was demonstrated and quantified by a marked drop in the insulin sensitivity index (S1) from 6.72 ± 0.77 to 2.47 ± 0.36 × 10−5 min−1/pM (P < .0001) and resulted in a doubling of basal immunoreactive insulin levels (from 75 ± 7 to 157 ± 21 pM, P < .001) with no change in fasting glucose (5.5 ± 0.1 vs. 5.7 ± 0.1 mM). Proinsulin levels also increased (from 9 ± 1 to 15 ± 2 pM, P < .005), but the ratio of proinsulin to immunoreactive insulin did not change (12.7 ± 1.9 vs. 10.3 ± 1.9%). β-Cell changes were characterized by increases in the AIR to glucose (from 548 ± 157 to 829 ± 157 pM, P < .005) and in the AIR to arginine at the fasting glucose level (from 431 ± 54 to 788 ± 164 pM, P < .05). At the maximal hyperglycemia level the AIR to arginine represents β-cell secretory capacity, and this increased with administration of NA (from 2062 ± 267 to 2630 ± 363 pM, P < .05). From the AIRs to arginine an estimate of the glucose level giving half-maximal AIR to arginine can be calculated. This measure did not increase (10.0 ± 0.5 vs. 9.6 ± 0.9 mM). The AGRs to argininewere reduced at all glucose levels during NA administration. Thus, the pancreatic islet adapts to the prolonged insulin resistance induced by NA. This adaptation comprises a combination of increased insulin secretion and reduced glucagon secretion. The changes in insulin secretion can be entirely explained by an increase in the secretory capacity of the β-cell.
Cross Correlation of Heart Rate and Respiration Versus Deep Breathing: Assessment of New Test of Cardiac Autonomic Function in Diabetes
Authors: Bernardi Luciano , Rossi Marco , Soffiantino Francesco , Marti Giuliano , Ricordi Luigi , Finardi Giorgio , Fratino Pietro
Published: September 2013

Cross correlation is a mathematical function whereby spectral analysis is used to describe the relationship between heart-rate fluctuations (256 R-R intervals) and respiration (simultaneously obtained by pneumotachograph). To assess its usefulness for testing autonomic integrity, cross correlation and deep breathing were compared in 141 diabetic subjects (aged 39 ± 14 yr) and in 77 control subjects (aged 33 ± 13 yr). To characterize patients, Valsalva maneuver, 30:15 ratio, tilt, and handgrip tests were performed in 96 of these patients; 23 had two or more abnormal tests (group A), 28 had one (group B), and 45 had none (group C). Sensitivity to parasympathetic withdrawal was compared in 9 control subjects (aged 26 ± 4 yr) by four sequential 0.01-mg/kg i.v. atropine administrations. Reproducibility was compared in 11 control subjects (aged 25 ± 2 yr) by repeating the tests four times for 2 consecutive days. Considering all 141 patients, cross correlation and deep breathing were <2SD of the mean of control subjects in 64 and 36 subjects, respectively. Considering patients who also performed other tests of autonomic function, cross correlation and deep breathing were <2SD of the mean of controls in 42 and 30 subjects, respectively (group A, 20 and 15; group B, 12 and 9; group C, 10 and 6). Cross correlation had better reproduciblity than deep breathing (C.V. 10.3 vs. 30.6% at 6 breaths/min) and greater sensitivity to atropine (after the 1st injection, cross correlation and deep breathing decreased to 34.6 and 48.2% of baseline values, respectively; P < .05). These data support the use of cross correlation to improve the diagnostic approach to cardiac autonomic damage.