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OBJECTIVE: Diabetes leads to protein kinase C (PKC)-beta overactivation and microvascular dysfunction, possibly resulting in disordered skin microvascular blood flow (SkBF) and other changes observed in diabetic peripheral neuropathy (DPN) patients. We investigate the effects of the isoform-selective PKC-beta inhibitor ruboxistaurin mesylate on neurovascular function and other measures of DPN. RESEARCH DESIGN AND METHODS: Endothelium-dependent and C fiber-mediated SkBF, sensory symptoms, neurological deficits, nerve fiber morphometry, quantitative sensory and autonomic function testing, nerve conduction studies, quality of life (using the Norfolk Quality-of-Life Questionnaire for Diabetic Neuropathy [QOL-DN]), and adverse events were evaluated for 20 placebo- and 20 ruboxistaurin-treated (32 mg/day) DPN patients (aged >/=18 years; with type 1 or type 2 diabetes and A1C

Objective: To review evidence for a relationship between dermal neurovascular dysfunction and other components of the metabolic syndrome of type 2 diabetes.Research Design and Methods: We review and present data supporting concepts relating dermal neurovascular function to prediabetes and the metabolic syndrome. Skin blood flow can be easily measured by laser Doppler techniques.Results: Heat and gravity have been shown to have specific neural, nitrergic, and independent mediators to regulate skin blood flow. We describe data showing that this new tool identifies dermal neurovascular dysfunction in the majority of type 2 diabetic patients. The defect in skin vasodilation is detectable before the development of diabetes and is partially correctable with insulin sensitizers. This defect is associated with C-fiber dysfunction (i.e., the dermal neurovascular unit) and coexists with variables of the insulin resistance syndrome. The defect most likely results from an imbalance among the endogenous vasodilator compound nitric oxide, the vasodilator neuropeptides substance P and calcitonin gene-related peptide, and the vasoconstrictors angiotensin II and endothelin. Hypertension per se increases skin vasodilation and does not impair the responses to gravity, which is opposite to that of diabetes, suggesting that the effects of diabetes override and counteract those of hypertension.Conclusions: These observations suggest that dermal neurovascular function is largely regulated by peripheral C-fiber neurons and that dysregulation may be a component of the metabolic syndrome associated with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Insulin resistance is a uniform finding in type 2 diabetes, as are abnormalities in the microvascular and macrovascular circulations. These complications are associated with dysfunction of platelets and the neurovascular unit. Platelets are essential for hemostasis, and knowledge of their function is basic to understanding the pathophysiology of vascular disease in diabetes. Intact healthy vascular endothelium is central to the normal functioning of smooth muscle contractility as well as its normal interaction with platelets. What is not clear is the role of hyperglycemia in the functional and organic microvascular deficiencies and platelet hyperactivity in individuals with diabetes. The entire coagulation cascade is dysfunctional in diabetes. Increased levels of fibrinogen and plasminogen activator inhibitor 1 favor both thrombosis and defective dissolution of clots once formed. Platelets in type 2 diabetic individuals adhere to vascular endothelium and aggregate more readily than those in healthy people. Loss of sensitivity to the normal restraints exercised by prostacyclin (PGI(2)) and nitric oxide (NO) generated by the vascular endothelium presents as the major defect in platelet function. Insulin is a natural antagonist of platelet hyperactivity. It sensitizes the platelet to PGI(2) and enhances endothelial generation of PGI(2) and NO. Thus, the defects in insulin action in diabetes create a milieu of disordered platelet activity conducive to macrovascular and microvascular events. [ABSTRACT FROM AUTHOR]

Objective: Noninsulinoma pancreatogenous hypoglycaemia syndrome (NIPHS), characterized by postprandial neuroglycopaenia, negative prolonged fasts and negative perioperative localization studies for insulinoma, but positive selective arterial calcium stimulation tests and nesidioblastosis in the gradient-guided resected pancreas, is a rare hypoglycaemic disorder of undetermined aetiology. We analysed the clinical, morphological and immunohistological features to further clarify the aetiology and pathogenesis of this rare disease., Patients: Ten consecutive patients with NIPHS (nine men and one woman, aged 29-78 years) were included in the study. Six of the 10 received a gradient-guided subtotal (70%) or distal (50%) pancreatectomy. In the remaining four patients, diazoxide treatment was initiated and the precise mechanism of its action was assessed by meal tests., Results: All of the patients showed a combination of postprandial neuroglycopaenia, negative prolonged fasts (except one patient) and negative localization studies for insulinoma, but positive calcium stimulation tests and nesidioblastosis in the gradient-guided resected pancreas. Immunohistological studies of the resected pancreatic tissues revealed neither an increased rate of proliferation of beta-cells nor an abnormal synthesis and/or processing of either proinsulin or amylin. Evidence of overexpression of the two pancreatic differentiation factors, PDX-1 and Nkx-6.1, as well as the calcium sensing receptor (CaSR) was absent. Nevertheless, abnormal expression of islet neogenesis-associated protein (INGAP), a human cytokine expressed only in the presence of islet neogenesis, in ducts and/or islets, was identified in three of the five patients studied. All of the six patients who received a surgical operation were relieved of further neuroglycopaenic attacks, but one patient who received a subtotal pancreatectomy developed diabetes. In the remaining four patients who received diazoxide treatment, hypoglycaemic episodes were satisfactorily controlled with an attenuated response of beta-cell peptides to meal stimulation., Conclusions: Our results strengthen the existence of this unique clinical hypoglycaemic syndrome from beta-cell hyperfunction as well as the value of the selective arterial calcium stimulation test in its correct diagnosis and localization. The mechanisms underlying beta-cell hyperfunction and release of insulin to calcium, however, remain poorly characterized. Nevertheless, in a subset of patients with NIPHS, there exists some, as yet undefined, pancreatic humoral/paracrine factor(s) other than proinsulin, amylin, PDX-1, Nkx-6.1 and possibly glucagon-like peptide-1 (GLP-1) that are capable of inducing the INGAP gene and, if activated, will initiate ductal proliferation and islet neogenesis. As for the treatment, we recommend that diazoxide be tried first in each patient and, should it fail, a gradient-guided subtotal or distal pancreatectomy be attempted.

What does the future hold for the person with diabetes, since current therapies, including insulin, are all symptomatic and do not address the underlying biology? This article reviews the current state-of-the-art strategies aimed at curing diabetes. The central rationale to curing diabetes revolves around replacing the function of pancreatic islets, either directly through pancreatic/islet transplantation, indirectly through artificial pancreas/beta cells, or via a rebirth of islet function by reprogramming the body to create a new and expanded islet cell mass protected from further assault by autoimmune and other processes. All of these approaches are considered in context of their current status, progress, future challenges or limitations, and long-term prospects for a cure. Although the horizon is in the distance, the advances reviewed in this study predict the future to be bright, and whereas the prospect of islet neogenesis was once considered to be heretical, it is now quite fashionable amongst the scientific community.

Neuropathy is one of the most debilitating complications of both type 1 and type 2 diabetes, with estimates of prevalence between 50-90% depending on the means of detection. Diabetic neuropathies are heterogeneous and there is variable involvement of large myelinated fibers and small, thinly myelinated fibers. Many of the neuronal abnormalities in diabetes can be duplicated by experimental depletion of specific neurotrophic factors, their receptors or their binding proteins. In experimental models of diabetes there is a reduction in the availability of these growth factors, which may be a consequence of metabolic abnormalities, or may be independent of glycemic control. These neurotrophic factors are required for the maintenance of the neurons, the ability to resist apoptosis and regenerative capacity. The best studied of the neurotrophic factors is nerve growth factor (NGF) and the related members of the neurotrophin family of peptides. There is increasing evidence that there is a deficiency of NGF in diabetes, as well as the dependent neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) that may also contribute to the clinical symptoms resulting from small fiber dysfunction. Similarly, NT3 appears to be important for large fiber and IGFs for autonomic neuropathy. Whether the observed growth factor deficiencies are due to decreased synthesis, or functional, e.g. an inability to bind to their receptor, and/or abnormalities in nerve transport and processing, remains to be established. Although early studies in humans on the role of neurotrophic factors as a therapy for diabetic neuropathy have been unsuccessful, newer agents and the possibilities uncovered by further studies should fuel clinical trials for several generations. It seems reasonable to anticipate that neurotrophic factor therapy, specifically targeted at different nerve fiber populations, might enter the therapeutic armamentarium.

The effect of breed and diet on insulin response to glucose challenge and its relation to intramuscular fat deposition was determined in 36 steers with 12 each of greater than 87% Wagyu (referred to as Wagyu), Wagyu x Limousin, and Limousin breeds. Weaned steers were blocked by weight into heavy, medium, and light calves and placed in six pens with two pens per weight type and with two steers of each breed per pen. Three pens with steers from each weightclass were fed backgrounding and finishing diets for 259 d, while the other three pens were fed the same diets where 6% of the barley grain was replaced with sunflower oil. Prior to initiation of the finishing phase of the study the intravenous glucose tolerance test (VGTIT) was conducted in all steers. Once steers were judged as carrying adequate 12th-rib fat, based on weight and days on feed, they were harvested and graded and samples of the longissimus muscle were procured for determination of fat content and fatty acid composition. Dietary oil improved (P = 0.011; 0.06) ADG and feed conversion efficiency of steers during the latter part of backgrounding and only ADG during early part ofthe finishing period. Generally percent kidney, pelvic, and heart fat was the only adiposity assessment increased (P = 0.003) by dietary oil. The IVGTT results indicated that insulin response to intravenous glucose was lower in Limousin steers than in Wagyu steers. Dietary oil decreased (P = 0.052) fasting plasma insulin concentration in Wagyu steers compared with Limousin steers. The correlation coefficients among the IVGTT measures and intramuscular fat content or marbling score were less than 0.4, and only a negative trend existed between fasting insulin and USDA marbling scores. However, the carcasses of the Wagyu steers graded US Choice, and 66% of the Wagyu carcasses graded US Prime, which were substantially better than the quality grades obtained for the carcasses from the other breed types. Dietary oil did not affect muscle fat content but increased (P = 0.01) conjugated linoleic acid (CLA) concentrations by 339%. Results indicated that IVGTT measures were not appropriate indices of marbling potential in cattle and that dietary oil can enhance CLA content of beef.

We report a case of severe hypoglycemia occurring in a 35-yr-old woman, 6 yr after pancreas transplantation for type 1 diabetes mellitus. Extensive preoperative and intraoperative exploration failed to disclose the presence of a focal adenomatous lesion. Partial allograft pancreatectomy was performed initially, but it failed to control the hypoglycemic symptoms, leading to complete removal of the pancreas allograft. Histopathological examination of the resected pancreas allograft showed the presence of nesidioblastosis, characterized by foci of islet cells budding off ducts, accompanied by an increase in the number of islets, numerous small intralobular islet cell aggregates, and nesidiodysplasia (large, hyperchromatic islet cell nuclei). Islet neogenesis-associated protein-positive islets and ducts were seen by immunofluorescence. Insulin-positive islets ranged from very small to large, with isolated insulin-positive cells diffusely scattered, consistent with islet neogenesis. Very little glucagon staining was identified. Reported cases of adult nesidioblastosis are reviewed. The significance of nesidioblastosis in the context of pancreas transplantation and possible mechanisms of posttransplant hypoglycemia are discussed.

Interleukin 6 (IL-6) plays a role in physiological and pathophysiological processes in neuronal cells. We studied whether IL-6 plays a role in neuroblastoma cells in culture. These studies demonstrate that N1E-115 cells constitutively express IL-6 but not IL-6R. Exogenous IL-6 stimulated neuronal proliferation in a dose-dependent manner. Under serum-free conditions soluble IL-6 receptors (sIL-6R) alone or in combination with IL-6 exerted significant proliferative effects, while IL-6 alone failed to promote cell proliferation. Neutralizing anti-IL-6 antibody caused a 30-40% reduction in IL-6 mediated proliferation. Our results suggest the importance of IL-6/sIL-6R for proliferation and survival of N1E-115 adrenergic neuroblastoma cells.

Partial obstruction of the adult hamster pancreas leads to islet cell differentiation and new islet formation. From morphologic and morphometric observations, we have tentatively identified the source of the new islet tissue to be from cells in the ducts. In this study, in vivo labeling with a single pulse of tritiated thymidine after partial duct obstruction was used to ascertain whether newly formed islet cells were in fact derived from cells in the ductal epithelium. Supportive evidence for this formulation was also sought using immunocytochemistry for islet hormones and in situ hybridization for glucagon and insulin mRNA to probe areas of proliferating duct cells. Endocrine cell differentiation was observed as a migration of cells out from small ducts beginning at about 10 days after obstruction. Duct and islet cell labeling indices (LI;%) in control animals remained at a low level (0.25 +/- 0.01 and 0.26 +/- 0.03, respectively) throughout the experiment. In contrast, at 2 weeks after partial obstruction, the duct and islet cell LI were 4.2 +/- 0.7 and 0.80 +/- 0.1 (p < 0.05 vs. control). After 2 weeks, there was a rapid and significant 86% decline in the duct cell LI to a low of 0.6 +/- 0.2 at 8 weeks, which was accompanied by a comparable, but reciprocal, 113% increase in the islet cell LI to a high of 1.7 +/- 0.8 (p < 0.05). In situ hybridization demonstrated glucagon and insulin mRNA-positive cells within intralobular ducts as early as 6 and 8 days, respectively, after obstruction. Glucagon and insulin peptides appeared in these cells at approximately 8 and 10 days, respectively, as cells migrated out from the duct wall. This study provides additional evidence that further supports our concept that pancreatic endocrine cell differentiation in this model reiterates the normal ontogeny of beta cell differentiation from cells in the ductular epithelium.

The pathogenesis of diabetic neuropathy is incompletely understood. The possibility that humoral neurotoxic factors contribute as a cause of diabetic neuropathy was tested by application of serum from patients with Type 1 and Type 2 diabetes to mouse neuroblastoma cells, which have the characteristics of adrenergic neurons in culture. Serum from patients with Type 1 diabetes and somatic neuropathy significantly inhibited both proliferation and differentiation of neuroblastoma cells, while serum from patients with Type 1 diabetes but no symptoms of neuropathy and patients with Type 2 diabetes and neuropathy had no effect on proliferation, and serum from Type 2 patients only marginally inhibited differentiation. The effects of Type 1 diabetic serum could be reversed by pre-absorption of the serum to neuroblastoma cells, and were independent of glucose levels. Immunoglobulins precipitated from the sera mimicked the effects of whole sera. These results suggest that Type 1 diabetes mellitus causes a change in serum composition, possibly related to autoimmunity, that is capable of contributing to adrenergic autonomic neuropathy in diabetic patients.

Although previously thought to arise from neural ectoderm, the endocrine cells of the gastrointestinal system are now believed to derive from endoderm. The role of different growth factors in initiation of endocrine cell growth, commitment of the cells to a particular growth pathway, and the initiation and maintenance of tumor growth and remission remains unclear. This article briefly reviews factors controlling cell growth and differentiation of gastrointestinal endocrine cells and presents data on new candidate growth factors pertinent to the authors' model of induction of endocrine cell differentiation in the pancreas.

We have established a model in which cellophane wrapping induces reiteration of the normal ontogeny of beta-cell differentiation from ductal tissue. The secretion of insulin is physiologic and coordinated to the needs of the animal. Streptozotocin-induced diabetes in hamsters can be 'cured' at least half the time. There appears to be activation of growth factor(s) within the pancreas acting in an autocrine, paracrine or juxtacrine manner to induce ductal cell proliferation and differentiation into functioning beta-cells. Given the results of our studies to date, it does not seem premature to envisage new approaches to the treatment of diabetes mellitus. Identification of the factor(s) which regulates islet cell proliferation and differentiation in our model may permit proto-undifferentiated cells and islets to be grown in culture. This concept could be extended to induce endocrine cell differentiation in vitro as well. Furthermore, islet cell growth factors could be used to provide 'trophic support' to islet transplants as a means of maintaining graft viability. There may also be greater scope for gene therapy when the growth factor(s) has been isolated, purified, sequenced and cloned.

We have established a model in which cellophane wrapping induces reiteration of the normal ontogeny of beta-cell differentiation from ductal tissue. The secretion of insulin is physiologic and coordinated to the needs of the animal. Streptozotocin-induced diabetes in hamsters can be "cured" at least half the time. There appears to be activation of growth factor(s) within the pancreas, acting in an autocrine, paracrine, or juxtacrine manner to induce ductal cell proliferation and differentiation into functioning beta cells. Given the results of our studies to date, it does not seem premature to envisage new approaches to the treatment of diabetes mellitus. Identification of the factor(s) regulating islet-cell proliferation and differentiation in our model may permit islets to be grown in culture. This concept could be extended to induce endocrine cell differentiation in vitro as well. Furthermore, islet-cell growth factors could be used to provide "trophic support" to islet transplants as a means of maintaining graft viability. There may also be greater scope for gene therapy when the growth factor(s) have been isolated, purified, sequenced, and cloned.

In this series of studies, we have presented evidence for a novel, pancreatic islet-specific growth factor, which we call ilotropin. Ilotropin is acid stable, heat stable, ethanol-precipitable, and sensitive to trypsin digestion. It appears to have a molecular weight between 29 - 44,000, and preliminary data not presented here suggests that it has a relatively basic pI. Unlike many other growth factors, ilotropin does not bind to heparin. Ilotropin is distinguishable from most of the known growth factors on the basis of at least one of the characteristics established in these studies. The apparent molecular weight of 29 - 44,000 eliminates all but the larger growth factors such as PDGF and hepatic growth factor. The fact that ilotropin is acid stable rules out identity with hepatic growth factor, and its lack of binding to heparin and apparent basic pI rules out identity with PDGF. Thus, the combination of characteristics described in these studies eliminates most of the known growth factors as candidates for the role of ilotropin. Certain growth factor precursor molecules (e.g. TGF-a) and several interleukins and cytokines (e.g. pro-IL-1 and melanocyte growth factor) also fall into this molecular weight range. Whether these proteins might be related to ilotropin or play a role in its biological activity remains to be determined. Current studies of ilotropin include further purification to homogeneity, determination of the peptide sequence of ilotropin, and development of an in vitro bioassay using trophic responses of primary cultures of pancreatic duct cells as an indicator of ilotropin activity. With purified material we ought to be able to identify the cells of origin and the target cells for the action of ilotropin, and establish assays to determine the relationship to failure of beta-cell regeneration that accompanies diabetes. Ultimately we hope that ilotropin may lead to new ways of approaching aspects of the problems presented in pancreatic beta-cell failure.

Changes in O2 consumption, O2 extraction, and intramural pH, resulting from a decreasing O2 delivery, were studied in the intact dog intestine. The O2 delivery was decreased by ischemia, hypoxia, and combined hypoxia-ischemia. A noninvasive approach for determining intramural pH based on the principle of tonometry was used. There was a strong correlation between the changes in intramural pH and intestinal O2 consumption as O2 delivery was decreased. Intramural pH and O2 consumption were initially maintained in the face of decreasing O2 delivery, but after a critical point they decreased. This critical point was 60.3 +/- 1.6% of base-line O2 delivery in the ischemic group and 51.3 +/- 2.7% of base line in the hypoxic-ischemic group. Despite a decrease to 36.0 +/- 5.6% of base-line O2 delivery, the intramural pH and O2 consumption did not decrease in the hypoxic group. O2 extraction increased with decreasing O2 delivery but did not plateau, indicating no diffusion limitation. The data suggest that blood flow is the major factor limiting intestinal O2 consumption. It is concluded that the noninvasive measure of intramural pH is a good marker of the adequacy of tissue oxygenation in canine intestine.

We have devised and validated an indirect method for measuring the intramural pH in the stomachs of patients in the intensive care unit and have assessed its value in predicting the occurrence of massive hemorrhage from stress ulceration. The 103 patients, studied on an average of 3.8 +/- 0.6 consecutive days, were assigned to one of five groups: no bleeding, weakly positive guaiac, strongly positive guaiac, massive bleeding from an extragastric site, and massive bleeding from stress ulceration. The pH in gastric juice, arterial blood, and the wall of the stomach, PCO2 and PO2 in gastric juice and arterial blood, and [HCO3-] in arterial blood were recorded, together with history of treatment with antacids, cimetidine, and heparin and the number of risk factors known to be associated with bleeding from stress ulceration. Massive bleeding from stress ulceration occurred in 7 patients, all of whom were receiving antacids. Six of these patients died. A logistic analysis of the data obtained showed that the occurrence of bleeding from stress ulceration was best predicted by consideration of the combination of the number of risk factors and intramural pH (p less than 0.0001). Prediction by these variables was not improved by inclusion of any of the other variables recorded. Bleeding from stress ulceration was only seen in patients whose intramural pH had fallen below the lower limit of normality. The data indicate that intensive care unit patients would be better monitored if the intramural pH were measured, and that the occurrence of massive bleeding from stress ulceration would be better averted by maintaining the intramural pH at normal levels.