bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Brain in Counterregulation of Insulin-Induced Hypoglycemia in Dogs
Authors: Biggers David W , Myers Sharon R , Neal Doss , Stinson Randy , Cooper Neil B , Jaspan Jonathan B , Williams Phillip E , Cherrington Alan D , Frizzell R Tyler
Published: September 2013

The role of the brain in directing counterregulation during hypoglycemia induced by insulin infusion was assessed in overnight-fasted conscious dogs. Concomitant brain and peripheral hypoglycemia was induced in one group of dogs (n = 5) by infusing insulin peripherally at a rate of 3.5 mU · kg−1 · min−1. In another group (n = 4), insulin was infused as described above to induce peripheral hypoglycemia, and brain hypoglycemia was minimized by infusing glucose bilaterally into the carotid and vertebral arteries to maintain the brain glucose level at a calculated concentration of 85 mg/dl. Glucose was also infused peripherally as needed so that the peripheral glucose levels in both of the protocols were similar (45 ± 2 mg/dl with and 48 ± 3 mg/dl without brain glucose infusion, both P < .05). The responses (in terms of change of area under the curve) of epinephrine, norepinephrine, cortisol, and pancreatic polypeptide when brain glycemia was controlled during insulin infusion were only 14 ± 6, 39 ± 12, 17 ± 8, and 9 ± 4%, respectively, of those present during insulin infusion without concomitant brain glucose infusion (all P < .05). Of particular interest was the glucagon response that occurred when head hypoglycemia was minimized; the glucagon level was only 21 ± 8% of that present when marked brain hypoglycemia accompanied insulin infusion (P < .05). During hypoglycemia resulting from insulin infusion, endogenous glucose production (EGP), as assessed with [3-3H]glucose, rose from 2.6 ± 0.1 to 4.4 ± 0.5 mg · kg−1 min−1 (P < .05). In contrast, EGP decreased from 2.7 ± 0.2 to 2.0 ± 0.3 mg · kg−1 · min−1 When brain hypoglycemia was minimized. In an additional set of studies, when insulin was infused at 3.5 mU · kg−1 · min−1 and glucose was infused peripherally to maintain both the head and peripheral glucose concentrations at 88 ± 6 mg/dl, EGP decreased from 2.6 ± 0.1 to 1.2 ± 0.2 mg · kg−1 · min−1. These results suggest that under marked hyperinsulinemic conditions the brain is the primary director of glucagon release and that it is responsible for ∼ 75% of the life-sustaining glucose production.
Pancreas-Graft Immunogenicity and Pretreatment With Anti-Class II Monoclonal Antibodies
Authors: Lloyd David M , Cotler Scott J , Letai Anthony G , Stuart Frank P , Thistlethwaite J Richard
Published: September 2013

Pretreatment of organ allografts to reduce graft immunogenicity is an attractive and potentially clinically applicable concept. We have studied the effect of perfusing rat pancreases with anti-class II monoclonal antibody (MoAb), to remove class IIpositive accessory cells from the intact organ, on prolongation of allograft survival after transplantation. The capacity of pancreatic islets obtained from these perfused organs to stimulate proliferation of allogeneic T-lymphocytes was studied in a mixed isletlymphocyte culture (MILC). There was a significant prolongation in pancreas-allograft survival when intact pancreases were transplanted after a 3-h normothermic perfusion with MoAb reactive with class II antigens (16.2 ± 3.6 days, n = 19) compared with control animals (11.0 ± 1.4 days, n = 24). In vitro treatment of islets with MoAb and complement (CI) inhibited their stimulatory capacity in the MILC, as measured by [3H]thymidine uptake. Similarly, the stimulatory capacity of islets removed from perfused pancreases was also abrogated when MoAb was included in the perfusate. Although reduction in graft immunogenicity, by increasing allograft survival, was achieved by a 3-h pretreatment regimen, it was not sufficient to inhibit rejection altogether in our transplant model.
Improvement of Canine Pancreas-Allograft Survival With Diagnosis of Rejection by Fine-Needle Aspiration Biopsy
Authors: Ekberg Henrik , Allen Richard DM , Greenberg Merle L , Stewart Graeme J , Deane Stephen A , Little J Miles
Published: September 2013

Early diagnosis of rejection in pancreas-allograft transplantation remains a clinical challenge. The aim of this study was to assess the ability of antirejection therapy to reverse rejection when the diagnosis was based on either fine-needle aspiration biopsy (FNAB) or urinary amylase (UA). Sixteen dogs received a totalpancreas allograft with exocrine drainage into the bladder. Initially, a deliberately low dose of cyclosporin was given. Monitoring included percutaneous FNAB with ultrasound guidance and fasting spot measurements of UA. The diagnosis of rejection was made in alternate dogs when UA fell to <5000 IU/L (group A) or when the total corrected increment (TCI) of aspirated infiltrating cells was >2.6 (group B). Antirejection therapy consisted of 10 mg · kg−1 · day−1 i.v. methylprednisolone for 5 days and an increased dose of cyclosporin (25 mg · kg−1 · day−1). The median allograft survival was 9 days (range 8–19) in group A and 32 days (range 10–63) in group B (P = .01). A fall in UA permitted the successful reversal of rejection in only one of six grafts, whereas five of seven grafts were successfully treated when rejection diagnosis was based on FNAB. In conclusion, early diagnosis of rejection was achieved by FNAB, improving the ability of antirejection therapy to reverse pancreas-allograft rejection and prolong survival.
Crossover Study on Effects of Duct Obliteration, Celiac Denervation, and Autotransplantation on Glucose- and Meal-Stimulated Insulin, Glucagon, and Pancreatic Polypeptide Levels
Authors: Gooszen Hein G , Van Der Burg Michael PM , Guicherit Onno R , Jansen Jan BMJ , Frölich Marijke , Van Schilfgaarde Reinout , Lamers Cornelis BHW
Published: September 2013

In segmental-pancreas transplantation the body and tail of the pancreas are used. In an experimental study in dogs, the effects of sequentially conducted removal of the right pancreatic lobe (pancreatic head), duct obliteration, celiac denervation, and autotransplantation were studied according to a crossover design. Two groups of dogs were studied. In both groups the right lobe of the pancreas was removed at primary operation, and the duct of the transected left lobe (body and tail) was injected with fibrin sealant. The left lobe was completely freed from surrounding tissue (celiac denervation) in group 1 (n = 9), and the innervation of the left lobe was left intact in group 2 (n = 8). At 12 wk, two dogs in group 1 and four dogs in group 2 underwent successful autotransplantation of the left lobe. Pancreatic hormone secretion was stimulated by intravenous glucose injection and test-meal administration before primary operation and at 11 and 18 wk thereafter. The combination of removal of the right lobe and duct obliteration led to a decrease in glucose tolerance at both stimulation tests and a decrease in peripheral insulin release after intravenous glucose injection. At test-meal administration, no change in insulin and glucagon levels was demonstrated. If ceiiac denervation was added, similar results were obtained based on the understanding that the peripheral insulin release after the test meal was significantly elevated. Meal-stimulated pancreatic polypeptide response was abolished in both groups. Removal of the right lobe leads to parasympathic denervation of the left lobe, and celiac denervation mainly interferes with α-adrenergic innervation. Cholecystokinin was probably responsible for the absence of a decrease in insulin secretion at test-meal administration after primary operation. Secondary autotransplantation led to elevation of peripheral insulin release at both tests but had no demonstrable influence on glucose tolerance expressed in K values.
Fifteen Years' Experience With Pancreas Transplantation With Pancreaticoenterostomy
Authors: Groth Carl-Gustav , Tydén Gunnar , ÖStman Ja
Published: September 2013

We report on 92 pancreas transplantations with exocrine diversion by pancreaticoenterostomy. All recipients suffered from long-term type I (insulin-dependent) diabetes. In most transplantations, cadaveric segmental grafts were used (n = 89). In a few patients, segmental grafts from related donors were used (n = 3), and in a few other patients, wholeorgan cadaveric grafts were used (n = 4). There were 9 retransplantations. Most pancreas transplantations were performed in uremie diabetic patients in combination with a kidney transplantation (n = 58). In a few patients the pancreas transplantation was performed after a kidney transplantation (n = 6). The remaining transplantations were in nonuremic diabetic patients who received only a pancreas (n = 25). Over the years, the results have improved considerably; in the 1986–1987 series the overall 1-yr patient survival (ps) and graft survival (gs) rates were 97 and 56%, respectively. The best results were achieved with the combined procedure (ps 100%, gs 77%); with pancreas only, the figures were inferior (ps 92%, gs 34%). Several factors explain the improved results. The incidence of graft thrombosis has been reduced by the use of anticoagulation, and posttransplantation pancreatitis has been reduced by avoiding ischemie injury to the graft. Cyclosporin has helped reduce the incidence of graft rejection, and monitoring of the exteriorized pancreatic juice has helped in the diagnosis of rejection.
Separation of Pancreatic Islets by Fluorescence-Activated Sorting
Authors: Gray Derek WR , Göhde W , Carter N , Heiden T , Morris PJ
Published: September 2013

To allow clinical pancreatic islet transplantation, the yield and purity of islets must be improved. Intravital staining of islets with neutral red is a specific, nontoxic technique for labeling islets of various species. Using neutral red-stained rat islets, we investigated the known fluorescence absorbance and emission spectra in comparison with unstained exocrine tissue and have shown that stimulation with light of wavelength between 500 and 560 nm produces detectable emission >610 nm, which is absent from unstained exocrine tissue. The PARTEC cell sorter is an inexpensive alternative to currently available fluorescence-activated cell sorters and has a sorting mechanism based on a piezoelectric valve. We made extensive modifications to this machine to allow passage of particles up to 300 μm diam. Using rat pancreas stained intravitally with neutral red and dispersed by intraductal collagenase technique, we have shown that islets can be accurately identified in a high-speed flow system and sorted to a purity of >90% islet tissue. The islets remain intact and viable as determined by supravital staining and isogeneic transplantation to the kidney capsule site. These studies prove the feasibility of separating intact islets by fluorescence-activated sorting.
Large-Scale Purification of Human Islets Utilizing Discontinuous Albumin Gradient on IBM 2991 Cell Separator
Authors: Lake Stephen P , Bassett P Drew , Larkins Audrey , Revell John , Walczak Karen , Chamberlain Julie , Rumford Gwyneth M , London Nick JM , Veitch Peter S , Bell Peter RF , James Roger FL
Published: September 2013

A new method is described for the large-scale purification of human pancreatic islets with a discontinuous gradient of bovine serum albumin formed on an IBM 2991 cell separator. Fifteen human pancreases were processed, and after density-gradient centrifugation, a mean of 2643 islets/ml pancreatic digest were recovered with a mean purity of 63% and contained in 430 μm mean vol. Viability of gradient-isolated islets was compared with that of non-densitygradient islets (handpicked) and showed no difference in function. This technique allows isolation of intact, viable human islets of Langerhans of sufficient purity for potential human transplantation.
Immunoelectron Microscopic Localization of MHC Structures in Isolated Pancreatic Rat Islets
Authors: Gaudecker Brita Von , Ulrichs Karin , Müller-Ruchholtz Wolfgang
Published: September 2013

An immunogold-silver enhancement technique, which combines effective labeling of viable isolated islets with the ultrastructural resolution of cytological details, was applied in electron microscopy to identify major histocompatibility complex (MHC) structures on islet cells. Incubation of freshly isolated islets from CAP (RT1c) and LEW (RT1i) rats with OX18, an MHC class I antibody, showed strong positive reactivity in macrophages and/or dendritic-like cells (Mø-DCs) and vascular endothelial cells (VEs) and a comparatively weaker reactivity in endocrine α-, β-, and δ-cells. With MHC class II antibody OX6 (anti-I-A), Mø-DCs were strongly labeled in both rat strains on the surface and on internal structures. Three of five particularly high titered batches of OX6 revealed MHC class II expression on VE and β-cells. Four days of in vitro culture in combination with a high concentration of glucose and interferon-γ induced strong enhancement of MHC class I structures and, to a lesser extent, class II structures on β-cells.
Effect of Immunodepletion of MHC Class II-Positive Cells From Pancreatic Islets on Generation of Cytotoxic T-Lymphocytes in Mixed Islet-Lymphocyte Coculture
Authors: Stock Peter G , Ascher Nancy L , Platt Jeffrey L , Kaufman Dixon B , Chen Sally , Field Marion J , Sutherland David ER
Published: September 2013

In vitro manipulation of pancreatic islets to decrease islet immunogenicity before transplantation has largely been directed at eliminating the major histocompatibility complex (MHC) class ll-positive passenger leukocytes from the islets. The mixed islet-lymphocyte coculture (MILC) system was used to quantitate the efficacy of immunodepletion of MHC class II-positive cells from pancreatic islets in terms of reducing immunogenicity. With these experiments we compared the in vitro immunogenicity of MHC class II-depleted islets with untreated islets. B10.BR (H-2k) islets were treated with anti-lak alloserum followed by complement. This treatment successfully eliminated MHC class II-positive cells from the islets, as demonstrated by indirect immunofluorescence techniques. Depleted islets generated slightly lower amounts of allospecific cytotoxic T-lymphocyte (CTL) activity when exposed to C57BL/6 (H-2b) splenocytes in the MILC than untreated control islets. Although the amount of CTL generated by the depleted islets was slightly less than that generated by untreated islets, there was significant stimulation of CTL by the MHC class II-depleted islets. Therefore, the presence or absence of MHC class II cells within the islet is unlikely to be the decisive factor contributing to islet immunogenicity.
Prevention of Recurrent Diabetes in BB Rats After Islet Transplantation by Monoclonal Antibody Therapy
Authors: Markmann James F , Jacobson Jill D , Brayman Kenneth L , Kimura Hiromitsu , Barker Clyde F , Naji Ali
Published: September 2013

Two immune responses imperil pancreatic islet allografts transplanted into subjects afflicted with autoimmune diabetes: 1) the well-described allograft response that is mounted against tissues bearing foreign transplantation antigens and 2) a recurrence of the β-cell-specific autoimmune process responsible for the primary disease. To define the role of autoimmune response to transplanted islets, the possibility of a rejection response must be prevented. To accomplish this in spontaneously diabetic BB rats, we induced neonatal tolerance. We found that recurrent autoimmunity in tolerant BB rats can be prevented by treatment of recipients with the monoclonal antibody OX8 (specific for cytotoxic T-lymphocytes) but not W3/25 (specific for helper T-lymphocytes). These findings provide direct evidence for the role of OX8-bearing lymphocytes in autoimmune diabetogenesis.
Metabolic Function of Intraportal and Intrasplenic Islet Autografts in Cynomolgus Monkeys
Authors: Sutton Robert , Gray Derek WR , Burnett Melanie , McShane Philip , Turner Robert C , Morris Peter J
Published: September 2013

Intraportal islet autografting can restore near-normal glucose homeostasis in large diabetic animals, but the long-term failure rate of such grafts remains high. To assess the effect of the site of transplantation, we compared the hormonal responses to glucose (500 mg/kg i.v.) of intraportal (IP) and intrasplenic (IS) islet autografts in the cynomolgus monkey previously rendered diabetic by total pancreatectomy. Intravenous glucose tolerance tests (IVGTTs) 6 wk after IP grafting (n = 10) demonstrated nearly normal plasma glucose changes, with qualitatively normal but quantitatively reduced insulin and glucagon responses; only two animals have maintained these responses for >2 yr. IVGTTs 6 wk after IS grafting (n = 4) demonstrated more abnormal plasma glucose changes, with qualitatively normal but weak insulin responses and glucagon levels that did not fall in response to hyperglycemie; only one animal has maintained fasting normoglycemia for >9 mo. These results suggest that IS transplantation confers no benefit over IP transplantation in this model.
Influence of Hyperglycemia on Blood Perfusion of Autotransplanted Pancreatic Islets in Diabetic Rats
Authors: Jansson Leif , Sandler Stellan
Published: September 2013

One week after a partial pancreatectomy, which did not affect glucose homeostasis, adult rats were autotransplanted with 500 isolated pancreatic islets beneath the renal capsule. Some rats were rendered diabetic with streptozocin (STZ) before being implanted with the islets, and other rats received no STZ and thus remained normoglycemic. The number of implanted islets was insufficient to revert hyperglycemia, but the STZ-induced diabetic animals were treated with insulin according to one of the following protocols: 1) one daily subcutaneous insulin injection for 28 days after transplantation; 2) insulin injection on days 1–14; 3) insulin injection on days 15–28; or 4) no insulin. Four weeks after transplantation, the blood perfusion of the islet grafts was determined by a microsphere technique. Continuous hyperglycemia after implantation of the islets significantly decreased the volume of the graft and the blood flow per volume compared with normoglycemic animals also receiving islet transplants. Insulin treatment counteracted the decrease in both of these values. This result was achieved regardless of whether the insulin treatment was maintained throughout the 4-wk period or only during the first or second half. The mechanism behind the impaired blood perfusion of the grafts during continuous hyperglycemia is unknown, but it may reflect an effect on the revascularization of the graft or on the intrinsic regulation of the blood perfusion of the graft.
Prevention of Detrimental Effect of Cyclosporin A on Vascular Ingrowth of Transplanted Pancreatic Islets With Verapamil
Authors: Rooth Pål , Dawidson Ingemar , Lafferty Kevin , Diller Ken , Armstrong John , Pratt Phil , Simonsen Randall , Täljedal Inge-Bert
Published: September 2013

The revascularization of pancreatic islet clusters transplanted beneath the renal capsule was studied in a syngeneic mouse model. The degree of vascular ingrowth was visualized by in vivo fluorescence microscopy (fluorescein isothiocyanate-dextran) and judged by a semiquantitative method from coded video recordings. The recipients of isografts were divided into four groups, depending on their daily immunosuppressive treatment: 1) none (controls), 2) 15 mg/kg cyclosporin A (CsA), 3) 0.4 mg/kg verapamil + 15 mg/kg CsA, and 4) 20–30 mg/kg methylprednisolone. In control animals, capillary ingrowth was first demonstrated on day 6, followed by progressive vascularization up to day 34. After 6 mo, the vascular architecture was similar to that seen in normal islets in situ. CsA alone significantly decreased vascular ingrowth on day 14 compared with controls (P < .02). Verapamil prevented the detrimental effect of CsA (P < .01), probably by improving renal subcapsular blood flow. Methylprednisolone did not affect revascularization compared with control animals at day 14. We conclude that CsA inhibits vascular ingrowth into transplanted pancreatic islets, which is likely to have clinical implications. The prevention of CsA vascular ingrowth inhibition by a calcium antagonist indicates a possible approach to the correction of this problem, particularly when the renal capsule is used as the recipient's transplant site.
Evaluation of Microencapsulated Islets in Agarose Gel as Bioartificial Pancreas by Studies of Hormone Secretion in Culture and by Xenotransplantation
Authors: Iwata Hiroo , Amemiya Hiroshi , Matsuda Takehisa , Takano Hisateru , Hayashi Ryosuke , Akutsu Tetsuzo
Published: September 2013

Islets were microencapsulated in agarose gel for examiNatlon of the possible use of microencapsulated islets as a bioartificial pancreas. Microencapsulated islets secreted insulin into the culture medium (RPMM640) and could rapidly increase their insulin release in response to a glucose challenge even after >100 days. Hamster islets in groups of 400–1000 encapsulated in microbeads containing 11–14% (wt/wt) agarose were xenogenically transplanted into the peritoneal cavity of five diabetic mice. The longest normoglycemic period in these mice was 53 days, which was markedly longer than the normoglycemic period obtained by nonencapsulated islets. Agarose seems to be a suitable basic material for encapsulating islets, because the islets can easily be microencapsulated without any adverse effect on the islet function.
Application of Magnetic Resonance Imaging in Pancreas Transplant
Authors: Yuh William TC , Hunsicker Lawrence G , Sato Yutaka , Wright Francis H , Smith John L , Corry Robert J
Published: September 2013

Various imaging methods have been used in the differential diagnosis of pancreas-transplant dysfunction. As early as 1977, angiography and radionuclide studies ([75Se]seleno-DL-methionine) were used to evaluate pancreas allografts. More recently, the use of 99mTc-labeled DTPA, computed tomography, and ultrasonography has been described, and abnormal findings associated with rejection have been reported with these imaging methods. However, no attempt has been made to determine the ability of each method to detect rejection and to differentiate graft dysfunction caused by rejection from dysfunction by other causes. We summarize our experience with the application of magnetic resonance imaging (MRI) in pancreas transplantation and a comparative study of radionuclide 99mTc-DTPA scans, ultrasonography, and MRI in the detection and differentiation of pancreas-graft dysfunction.
Insulin-Pump Treatment of Pancreas-Graft Rejection
Authors: Bartoš Vladimír , Vaněk Ivan , Dryáková Marie , Saudek František , Malý Jan
Published: September 2013

Continuous subcutaneous insulin infusion (CSII) was combined with antirejection therapy in four diabetic recipients of pancreas and kidney grafts with persisting hyperglycemia due to pancreas rejection. In three of the patients, full function of the pancreas was restored after as many as 40, 86, and 139 days of CSII. In another patient, the dose of insulin was halved, and his graft function was classified as partial. Pancreas rejection treated without CSII was reversible only in one of four other recipients. We conclude that restoration of the function of a pancreas graft damaged by rejection can be achieved even after a long period with the help of CSII therapy.
Islet Cell Autoimmunity in Type I Diabetic Patients After HLA-Mismatched Pancreas Transplantation
Authors: Bosi Emanuele , Bottazzo Gian Franco , Secchi Antonio , Pozza Guido , Shattock Marion , Saunders Anna , Gelet Albert , Touraine Jean Louis , Traeger Jules , Dubernard Jean-Michel
Published: September 2013

The aim of this study was to investigate a possible reenhancement of islet cell autoimmunity in type I (insulin-dependent) diabetic patients who received HLA-mismatched pancreas transplants from cadaveric donors and who underwent generalized immunosuppression. Circulating islet cell antibodies (ICA) and complement-fixing ICAs (CF-ICAs) have been tested at 1, 2, 3, 6, and 12 mo and at least once a year posttransplantation in 23 recipients of 25 transplants (22 simultaneous with kidney, 2 retransplants, 1 isolated; 23 segmentai neoprene injected, 2 whole with enteric drainage). Patients were aged 35.3 ± 1.9 yr with a duration of diabetes of 20.6 ±1.1 yr. Immunosuppression consisted of double or triple association of azathioprine, cyclosporin, and prednisone with or without temporary antilymphocyte globulins. The number of HLA-A and HLA-B compatibilities was none in 8 patients, one in 12 patients, two in 4 patients, and three in 1 patient. The mean follow-up was 4.0 ± 0.4 yr/patient (range 0.4–7.2). ICAs were positive pretransplantation in 2 of 25 patients and reappeared 1–42 mo posttransplantation in another 7. In 6 patients, CF-ICAs were also positive. In 7 of 9 ICA+ patients the pancreas transplant failed; in 1 patient this occurred 4 mo before ICA reappearance, and in 6 patients it occurred 2–35 mo after the first detection of ICAs. Pancreas-transplant failure was significantly associated with the positivity for ICAs (P < .05) and particularly for CF-ICAs (P < .005). ICA positivity was transitory in 4 patients (2–27 mo) and persistent in the remaining 5 (up to 61 mo). These findings suggest a possible reenhancement of islet cell autoimmunity in type I diabetic patients after HLA-mismatched pancreas transplantation, which could contribute to some cases of transplant failure.
Deferoxamine Therapy in High-Ferritin Diabetes
Authors: Cutler Paul
Published: September 2013

Serum ferritin and diabetes control were evaluated in 18 White patients with poorly controlled type II (noninsulin-dependent) diabetes who had no known causes of iron-storage disorder. Serum ferritin levels were found to be elevated with normal serumiron and total iron-binding capacity in 9 of the 18 patients studied. Because excess iron, typified by hemochromatosis, is associated with diabetes, and diabetes has been shown to improve after lowering total-body iron load through repeat venesection, I investigated whether regulating elevated ferritin levels could facilitate diabetes control. Deferoxamine (DFO), a known specific chelator of iron, was used because of its capacity to correct excess iron stores. All 9 patients in the high-ferritin diabetic group and 7 of 9 diabetic control subjects with normal serum ferritin levels were given DFO (10 mg/kg i.v.) twice weekly. Diabetic control, fasting glucose, triglyceride, cholesterol, HbA1c, and serum ferritin levels were monitored. Data show that lowering elevated ferritin levels correlated well with diabetes control and improved fasting glucose, triglyceride, and HbA1c in 8 of 9 patients with high ferritin levels. Lowering normal ferritin levels had no effect on diabetes control or on any ofthe other parameters in the 7 control subjects. This study shows there is a need to study iron metabolism in poorly controlled diabetes and demonstrates the value of DFO in controlling high-ferritin diabetes.
Prevention of Hemodynamic and Vascular Albumin Filtration Changes in Diabetic Rats by Aldose Reductase Inhibitors
Authors: Tilton Ronald G , Chang Katherine , Pugliese Giuseppe , Eades Donald M , Province Michael A , Sherman William R , Kilo Charles , Williamson Joseph R
Published: September 2013

This study investigated hemodynamic changes in diabetic rats and their relationship to changes in vascular albumin permeation and increased metabolism of glucose to sorbitol. The effects of 6 wk of streptozocin-induced diabetes and three structurally different inhibitors of aldose reductase were examined on 1) regional blood flow (assessed with 15-μm 85Sr-labeled microspheres) and vascular permeation by 125I-Iabeled bovine serum albumin (BSA) and 2) glomerular filtration rate (assessed by plasma clearance of 57Co-labeled EDTA) and urinary albumin excretion (determined by radial immunodiffusion assay). In diabetic rats, blood flow was significantly increased in ocular tissues (anterior uvea, posterior uvea, retina, and optic nerve), sciatic nerve, kidney, new granulation tissue, cecum, and brain. 125I-BSA permeation was increased in all of these tissues except brain. Glomerular filtration rate and 24-h urinary albumin excretion were increased 2- and 29-fold, respectively, in diabetic rats. All three aldose reductase inhibitors completely prevented or markedly reduced these hemodynamic and vascular filtration changes and increases in tissue sorbitol levels in the anterior uvea, posterior uvea, retina, sciatic nerve, and granulation tissue. These observations indicate that early diabetes-induced hemodynamic changes and increased vascular albumin permeation and urinary albumin excretion are aldose reductase-linked phenomena. Discordant effects of aldose reductase inhibitors on blood flow and vascular albumin permeation in some tissues suggest that increased vascular albumin permeation is not entirely attributable to hemodynamic changes. We hypothesize that 1) increases in blood flow may reflect impaired contractile function of smooth muscle cells in resistance arterioles and 2) increases in vascular 125I-BSA permeation and urinary albumin excretion reflect impaired vascular barrier functional integrity in addition to increased hydraulic conductance secondary to microvascular hypertension associated with decreased vascular resistance.
Diabetes and Impaired Response of Glucagon Cells and Vascular Bed to Adenosine in Rat Pancreas
Authors: Gross René , Hillaire-Buys Dominique , Bertrand Gyslaine , Ribes Gérard , Loubatieres-Mariani Marie-Madeleine
Published: September 2013

Previous studies have shown that adenosine, by activation of purinergic A2-receptors, stimulates glucagon secretion and increases vascular flow rate in isolated perfused pancreases from nondiabetic rats. Because α-cell function and blood flow control are known to be disturbed in diabetes, we investigated whether adenosine was still effective in streptozocininduced diabetic (STZ-D) rats. Our experiments were performed on isolated perfused rat pancreases. Whereas, in normal rats, adenosine (1.65 μM) induced a 200% increase in glucagon output and a 25% rise in the pancreatic vascular flow rate, in rats diabetic for 5–6 wk, this nucleoside was ineffective on glucagon secretion, and its vasodilatory effect was strongly reduced. Long-term in vivo insulin treatment that reversed high glycemia levels was able to restore in large part both adenosine effects. In contrast, a shortterm in vitro pretreatment with insulin was unable to restore the nucleoside effects. We conclude that STZ-D suppresses the stimulatory effect of adenosine on α-cells and strongly reduces its vasodilator properties; these abnormalities may be corrected in large part by long-term insulin treatment with normalization of glycemia.
Age-Dependent Stimulation of Neonatal Insulin Release and Inositol Phosphate Accumulation by CCK-8 and Carbachol
Authors: Fletcher Donald J , Rowley Wesley H , Pabst Susan J , Brinn Jack E
Published: September 2013

Development of a robust insulin secretory response to glucose occurs during the early neonatal period. To determine if neuroendocrine agents play a role during this time, we studied the effects of selected peptides and neurotransmitters on insulin release and polyphosphoinositide metabolism in islets isolated from 1- and 3-day neonatal rats. Vasoactive intestinal peptide had no effect on glucose-stimulated release in either islet population. In contrast, sulfated cholecystokinin octapeptide (CCK-8) significantly enhanced glucose-induced insulin release in both islet groups. One-day islets were stimulated only by a concentration of 300 nM, whereas 3-day islets were responsive at 3 nM. Similar to CCK-8, there were clear differences in responses to carbachol between 1- and 3-day islets. One-day islets required a concentration of 200 μM for insulin release to be significantly greater than with glucose alone; 3-day islet insulin release was significant at 2 μM carbachol. Both agonists stimulated inositol phosphate accumulation in 3-day islets, but only CCK-8 caused a significant increase over glucose-induced levels in 1-day islets. These results indicate that islet responsiveness to CCK-8 and carbachol develops in parallel during the early neonatal period. This development may be linked to the maturation of a critical step of stimulus-secretion coupling through which these agents act.
Long-Term Effects of Vanadyl Treatment on Streptozocin-Induced Diabetes in Rats
Authors: Pederson Raymond A , Ramanadham Sasanka , Buchan Alison M J , McNeill John H
Published: September 2013

The vanadate and vanadyl forms of vanadium have been shown by many investigators to have insulinlike effects on glucose metabolism. Many investigators have shown that vanadium, or its salts, counteracts the hyperglycemie associated with streptozocin-induced diabetes (STZ-D) in the rat, although insulin secretion remains depressed. Studies of the action of vanadate on insulin secretion and glucose metabolism have not addressed the question of possible long-term effects of this compound on glucose metabolism extending beyond the period of oral administration. This study was undertaken to assess the effects of treatment (3 wk) and withdrawal of vanadyl sulfate (13 wk) on glucose metabolism, insulin secretion, and islet insulin content of STZ-D rats. Our results indicate that STZ-D rats that have had blood glucose levels normalized by 3 wk of vanadyl treatment remain normoglycemic after 13 wk of withdrawal from treatment. Normal glucose tolerance was observed in vanadyl-treated diabetic animals despite depressed fasting and glucose-stimulated plasma insulin levels. Insulin secretion from the isolated perfused pancreas was greater after vanadyl treatment than in untreated diabetic rats, although it was only 12% of values from controls. Three weeks of vanadyl treatment of STZ-D rats, followed by 13 wk of withdrawal, yielded islets close in size and insulin content of control islets, even though in vivo and in vitro insulin secretion was impaired. This study has shown that short-term vanadyl treatment of STZ-D rats yields normalization of glucose tolerance and protection of islets from destruction by STZ. The relationship between normal glucose tolerance, normal islet insulin content, and reduced insulin secretion in vanadyl-treated STZ-D rats remains to be investigated.
Correlation Between Residual β-Cell Function and Islet Cell Antibodies in Newly Diagnosed Type I Diabetes: Follow-Up Study
Authors: Peig Montserrat , Gomis Ramon , Ercilla Guadalupe , Casamitjana Roser , Bottazzo Gian Franco , Pujol-Borrell Ricard
Published: September 2013

To establish whether there is a correlation between the autoimmune response to the islets and β-cell function during the initial stages of type I (insulin-dependent) diabetes, an islet cell antibody (ICA) titer and C-peptide levels (fasting and glucagon stimulated) were determined in 39 newly diagnosed patients at onset of diabetes and every 3–6 mo for 2 yr. ICAs were detected in 74% of the patients, and β-cell function was detected in 84% of the patients at onset. The ICA+ and ICA− groups had similar C-peptide values at diagnosis and at 3 mo, but from 6 mo on, the ICA+ group consistently showed a tendency to lose C-peptide secretory capacity more quickly when assessed by fasting and glucagon-stimulated C-peptide levels (ICA+ vs. ICA− fasting C-peptide levels at 18 and 24 mo, P = .013 and .017, respectively; ICA+ vs. ICA− glucagon-stimulated C-peptide levels at 6,18, and 24 mo, P = .023, .007, and .028, respectively). The initial ICA titer had the highest predictive value on the outcome of β-cell function (P = .04), and patients with complement-fixing ICAs did not behave differently from the general ICA+ group. This correlation between β-cell function and ICA titer supports the role of autoimmunity in the pathogenesis of type I diabetes and has important implications for the design of immunotherapy trials.
Fish Oil–Enriched Diet and Reduction of Low-Dose Streptozocin–Induced Hyperglycemia: Inhibition of Macrophage Activation
Authors: Linn Thomas , Noke Marlies , Woehrle Manfred , Kloer Hans U , Hammes Hans P , Litzlbauer Detlef , Bretzel Reinhard G , Federlin Konrad
Published: September 2013

Repeated low doses of streptozocin (STZ; 40 mg/kg, 5 injections/day) induce hyperglycemia in certain strains of mice after a latency of 1 wk. Omega-3 polyunsaturated fatty acids (ω3FA) have been reported to suppress immune processes by blockade of the cyclooxygenase pathway of arachidonic acid metabolism. We investigated the effects of diets high in ω3FA on the development of diabetes in the low-dose STZ-induced diabetes (LDSTZ-D) model. Male C57BL/6J mice were on a fish oil diet (FOD) as a source of ω3FA 8 wk before STZ injection. Controls received laboratory chow only or a coconut oil diet (COD). Blood glucose levels in FOD mice were reduced (12.5 vs. 28 mM for COD mice, P < .001) 60 days after STZ injection with a diet in which 20% of the calories were from fish oil. In FOD mice, immunohistology showed reduced numbers of class II antigen-expressing cells in pancreatic islets followed by a decreased extent of insulitis. FOD significantly decreased the number of Fc receptor-negative dendritic cells in cytospin preparations of islets isolated from diabetic mice. Interleukin 1–like activity of peritoneal exudate cell supernatants isolated from mice on FOD was reduced. FOD did not improve insulin secretion of isolated islets from LDSTZ-D mice. These data indicate a beneficial effect of FOD on the immune component of the mouse LDSTZ-D model.
Effect of Omega-3 Fatty Acids in Diet of Type I Diabetic Subjects on Lipid Values and Hemorheological Parameters
Authors: Rillaerts Eddy G , Engelmann Guy J , Camp Kristen M Van , Leeuw Ivo De
Published: September 2013

Twelve type I (insulin-dependent) diabetic subjects in stable metabolic control for at least 3 mo received a controlled diet containing 50% carbohydrate, 35% fat, and 15% protein. Calorie intake varied from 1800 to 2200 calories, depending on individual needs. Part of the polyunsaturated omega-6 fatty acids (ω6FAs) were isocalorically exchanged with ω3FAs (2.7 g/day provided by fish oil concentrates) for 10 wk. Subject selection was based on the fact that the atherogenic index (total cholesterol/high-density lipoprotein cholesterol [HDL-chol]) remained >5. Total cholesterol did not change, but HDL-chol (P < .05) increased significantly, and the mean ± SD atherogenic index decreased from 5.9 ± 1.1 to 5.1 ± 1.3. Plasma triglyceride levels also decreased (P < .05). There was a small (∼2%) but significant (P < .05) decrease of whole-blood viscosity at low shear rate because of a similarly small (∼2%) decrease (P < .05) of plasma viscosity. Erythrocyte viscosity values and the erythrocyte transit time, measured with the St. George's filtrometer, remained unchanged during fish oil intake. Four weeks after stopping the ω3FA administration, the triglyceride level was again increased (P < .05) and was even higher than the starting value (P < .05). Plasma and whole-blood viscosity also increased to the starting levels, demonstrating that lipid alterations are accompanied with blood viscosity changes in the presence of a stable metabolic control.
Reduction of Glycemic and Lipid Levels in db/db Diabetic Mice by Psyllium Plant Fiber
Authors: Watters Karen , Blaisdell Peter
Published: September 2013

The soluble plant fiber psyllium significantly reduced fasting glucose and total cholesterol levels in the C57BL/KsJ db/db diabetic mouse relative to placebo-fed mice. Insulin levels were significantly higher in psyllium-fed than placebo-fed animals, indicating this fiber may delay the progression of diabetes in the animal model. High-density lipoprotein cholesterol levels rose moderately in both psyllium- and placebo-fed animals during the study, whereas triglyceride levels remained unchanged in both groups. Psyllium's effect on glycemic, lipid, and hormone parameters was not explained by weight loss or reduced food intake; these were similar in psyllium- and placebo-fed animals during the study. Our results show that psyllium fiber can beneficially moderate glycemic and lipid parameters in the db/db diabetes model.
Flow-Cytometric Detection of Human Anti-Rat Insulinoma Antibodies in Relation to Anti-Human Islet Cell and Anti-Insulin Antibodies: Recognition of Distinct Antigens by Antibodies in Early Type I Diabetes
Authors: Lander Thomas , Nerl Christoph , Held Martin , Standl Eberhard , Mehnert Hellmut
Published: September 2013

Flow cytometry was recently introduced for the detection of antibodies in human serum to a cultured insulin-secreting rat insulinoma cell line (RINm5F) to investigate humoral immune reactivity in newly diagnosed type I (insulin-dependent) diabetic patients. Fifty-three patients were observed for 6–20 mo after clinical onset of diabetes with a reported duration of symptoms of <6 wk. Human anti-RINm5F antibodies were detected in 28%, human anti-islet cell antibodies in 62%, and anti-insulin autoantibodies in 36% of patients before initiation of insulin therapy. Occurrence of human anti-RINm5F antibodies at this stage was correlated with human anti-insulin autoantibodies rather than with the formation of anti-islet cell antibodies. Incidence of anti-RINm5F antibodies in individuals with duration of diabetes >6 wk was 38%, whereas human anti-islet cell antibodies and anti-insulin antibodies became detectable in 72 and 61% of the patients, respectively. These findings are in line with previous reports of immunoprecipitation by human diabetic serums of a 64,000-Mr antigenic structure in freshly prepared rat islet cells. The results suggest a reactivity of distinct classes of antibodies in serums of patients with type I diabetes to disparate antigens on human islet cells and cloned rat insulinoma cells and, moreover, reactivity to insulin as the secreted product. Further characterization of the reacting RINmSF antigens and prospective studies in subjects at risk for diabetes are required to validate the application of RIN cells to the investigation of immune mechanisms involved in the pathogenesis of human type I diabetes.
Insulin Regulation of Lipolysis in Nondiabetic and IDDM Subjects
Authors: Jensen Michael D , Caruso Michela , Heiling Valarie , Miles John M
Published: September 2013

To determine whether insulin regulation of lipolysis is abnormal in subjects with poorly controlled insulin-dependent diabetes mellitus (IDDM), free-fatty acid flux ([1-14C]palmitate) was measured under conditions ranging from complete insulin withdrawal to hyperinsulinemia. Seven nondiabetic and seven IDDM subjects were studied with the pancreatic clamp technique to control plasma insulin, growth hormone, and glucagon concentrations at the desired levels. Preliminary studies were performed to validate the experimental design. The palmitate flux response to insulin withdrawal (2.5 ± 0.2 vs. 2.5 ± 0.2 μmol · kg−1 · min−1) and maximally antilipolytic insulin concentrations (0.17 ± 0.02 vs. 0.23 ± 0.03 μmol · kg−1 · min−1) were not different in nondiabetic and IDDM subjects, respectively. In contrast, IDDM subjects required significantly greater plasma free-insulin concentrations to result in equivalent suppression of palmitate flux compared with nondiabetic subjects. Lipolysis was found to be very sensitive to insulin in nondiabetic humans, with half-maximal suppression occurring at plasma free-insulin concentrations of ∼12 pM (< 2 μU/ml). We conclude that adipose tissue lipolysis is normally exquisitely sensitive to insulin and that sensitivity, but not responsiveness to insulin, is impaired in poorly controlled IDDM.
Prevalence and Risk Factors for Micro- and Macroalbuminuria in Diabetic Subjects and Entire Population of Nauru
Authors: Collins Veronica R , Dowse Gary K , Finch Caroline F , Zimmet Paul Z , Linnane Anthony W
Published: September 2013

Rates of elevated urinary albumin concentration, defined as microalbuminuria (30–299 μg/ml) and macroalbuminuria (≥300 μg/ml), were determined on random morning urine specimens in the population of Nauru, which has a high prevalence of non-insulin-dependent diabetes mellitus. The prevalence of elevated urinary albumin levels in the total Nauruan population was very high: 26 and 30% of men and women, respectively, had microalbuminuria, whereas 13% of both sexes had macroalbuminuria. Of the subjects with macroalbuminuria, 66% had diabetes. The prevalence increased with worsening glucose tolerance; 26% of subjects with normal glucose tolerance had either micro- or macroalbuminuria, increasing to 43% of subjects with impaired glucose tolerance, 63% of newly diagnosed diabetic subjects, and 75% of previously diagnosed diabetic subjects. Associations between elevated urinary albumin concentration and putative risk factors were assessed for both the total population (n = 1184) and the diabetic subgroup alone (n = 318). Fasting plasma glucose and hypertension were the most important independent correlates for the whole population, whereas plasma creatinine was also important in diabetic subjects. Age at onset and duration of diabetes were not found to be significantly associated with elevated albumin concentration. In subjects with normal glucose tolerance, hypertension and hyperuricemia were the most important associated factors. These results suggest that blood glucose, blood pressure, and possibly obesity and plasma uric acid are important modifiable risk factors for both micro- and macroalbuminuria in this population.
Insulin Prevention of Altered Muscarinic Receptor–G Protein Coupling in Diabetic Rat Atria
Authors: Aronstam Robert S , Carrier Gerald O
Published: September 2013

Right atria from rats rendered diabetic by injection of streptozocin (STZ-D) for 8–10 wk are supersensitive to the negative chronotropic effects of muscarinic agonists but have decreased levels of muscarinic receptors and acetylcholinesterase activity. Insulin treatment completely prevents the development of these changes. The proportion of atrial muscarinic receptors displaying high-affinity agonist binding is lower in STZ-D rats; however, the sensitivity of high-affinity agonist binding to regulation by a guanine nucleotide (5′-guanylylimidodiphosphate) is greater in atria from diabetic rats. Again, insulin treatment eliminates these differences. These findings indicate that alterations in atrial muscarinic systems in STZ-D rats are a consequence of the elaboration of the diabetic state and suggest that an alteration of functional muscarinic receptor–G protein coupling contributes to the altered physiological responsiveness of the heart in diabetes.
Rapid Detection of IDDM Susceptibility With HLA-DQ β-Alleles as Markers
Authors: Trucco Giuliana , Fritsch Read , Giorda Roberto , Trucco Massimo
Published: September 2013

The allelic forms of the human leukocyte antigen (HLA)–DQ β-chain (DQB1) have been recognized as the best markers of insulin-dependent diabetes mellitus (IDDM) susceptibility. We describe a method that allows the recognition of these DQB1 alleles without the use of either allele-specific oligonucleotide probes or radioactive material. This method determines these alleles by electrophoretically separating restriction enzyme-generated fragments from the polymerase chain-reaction–amplified second exon of the HLA-DQB1 gene, which encodes the first domain of the protein chain. This digestion method, which is simpler and more rapid than the previously adopted hybridization method, is described in detail to enable individuals at any clinical laboratory to quickly ascertain IDDM susceptibility.