Carboxybetaine-modified succinylated chitosan-based beads encourage pancreatic β-cells (Min-6) to form islet-like spheroids under in vitro conditions.

In vitro, pancreatic β-cells tend to reduce their ability to aggregate into islets and lose insulin-producing ability, likely due to insufficient cell-cell and cell-matrix interactions that are essential for β-cell retention, viability and functionality. In response to these needs, surfaces of succinylated chitosan-based beads (NSC) were modified with zwitterionic carboxy-betaine (CB) moieties, a compatible osmolyte known to regulate cellular hydration state, and used to promote the formation of β-cell spheroids using a conventional 2D cell culture technique. The NSC were synthesised by ionic gelation and surface-functionalised with CB using carbodiimide chemistry.

The role of tumour suppressor PDCD4 in beta cell death in hypoxia.

Objective: Hypoxia is known to induce pancreatic beta cell dysfunction and apoptosis. Changes in Programmed Cell Death Gene 4 (PDCD4) expression have previously been linked with beta cell neogenesis and function. Our aim was to investigate the effects of hypoxia on cell viability, PDCD4 expression and subcellular localisation.

Evaluation of the fidelity of immunolabelling obtained with clone 5D8/1, a monoclonal antibody directed against the enteroviral capsid protein, VP1, in human pancreas.

Aims/hypothesis: Enteroviral infection has been implicated in the development of islet autoimmunity in type 1 diabetes and enteroviral antigen expression has been detected by immunohistochemistry in the pancreatic beta cells of patients with recent-onset type 1 diabetes. However, the immunohistochemical evidence relies heavily on the use of a monoclonal antibody, clone 5D8/1, raised against an enteroviral capsid protein, VP1. Recent data suggest that the clone 5D8/1 may also recognise non-viral antigens; in particular, a component of the mitochondrial ATP synthase (ATP5B) and an isoform of creatine kinase (CKB).

Pseudoislets as primary islet replacements for research: report on a symposium at King's College London, London UK.

Laboratory-based research aimed at understanding processes regulating insulin secretion and mechanisms underlying β-cell dysfunction and loss in diabetes often makes use of rodents, as these processes are in many respects similar between rats/mice and humans. Indeed, a rough calculation suggests that islets have been isolated from as many as 150,000 rodents to generate the data contained within papers published in 2009 and the first four months of 2010. Rodent use for islet isolation has been mitigated, to a certain extent, by the availability of a variety of insulin-secreting cell lines that are used by researchers world-wide.

Use of antisera directed against dsRNA to detect viral infections in formalin-fixed paraffin-embedded tissue.

Background: The detection of viral infection in paraffin-embedded, formalin-fixed tissue is notoriously difficult and often requires inherent knowledge about the specific virus being sought. For this reason, there is an ongoing need for reagents and methods which can identify a range of different virus types in paraffin embedded tissue.

Objectives: The aim of this study was to optimise and validate the use of antisera directed against dsRNA (>50 bp in length) in paraffin-embedded formalin-fixed tissue samples.

Immunopathology of the human pancreas in type-I diabetes.

Type 1 diabetes is a chronic autoimmune disease characterised by the selective destruction of pancreatic beta (β) cells. The understanding of the aetiology of this disease has increased dramatically in recent years by the study of tissue recovered from patients, from analysis of the responses of isolated islet and β-cells in tissue culture and via the use of animal models. However, knowledge of the immunopathology of type 1 diabetes in humans is still relatively deficient due largely to the difficulty of accessing appropriate samples.

Stent material surface and glucose activate mononuclear cells of control, type 1 and type 2 diabetes subjects.

In stent restenosis (ISR) has been described as an unaccomplished tissue healing and its rate is particularly high in diabetic patients. Evidence has been collected which relates the formation of ISR proteoglycan-rich neointimal tissue to the accumulation and protracted activation of macrophages around the stent metal struts. Here, the in vitro activation of mononuclear cells adhering to stainless steel (a material of choice in stent manufacturing) from control and diabetic (types 1 and 2) subjects was assessed in the presence of different glucose levels.

Monitoring exercise-induced changes in glycemic control in type 2 diabetes.

Purpose: The present study determined the efficacy of the Continuous Glucose Monitoring System (CGMS) during moderate exercise and monitored the changes in whole-day glucose profiles using the CGMS in individuals with and without type 2 diabetes.

Methods: Six, obese, diet-treated individuals with and four age-matched individuals without type 2 diabetes were monitored using the CGMS for 3 d. Subjects cycled at 90% of a predetermined lactate threshold for 1 h at approximately 09:00 h on day 2, during which venous blood was sampled at 10-min intervals and immediately analyzed for glucose concentrations.

Cell-to-cell contact influences proliferative marker expression and apoptosis in MIN6 cells grown in islet-like structures.

Cell-to-cell interactions play an important role in the development and maintenance of the beta-cell phenotype. Here, we have investigated whether E-cadherin plays a role in regulating the growth of insulin-secreting MIN6 cells configured as three-dimensional islet-like clusters (pseudoislets). Pseudoislets form by cell aggregation rather than by proliferation from individual cells and attain the size of primary mouse islets after approximately 7 days of maintenance in culture.

Repair of cytokine-induced DNA damage in cultured rat islets of Langerhans.

Treatment of cultured rat pancreatic islets of Langerhans with the combined cytokines interleukin-1beta (IL-1beta), interferon gamma (IFN gamma) and tumour necrosis factor alpha (TNF alpha) leads to DNA damage including strand breakage. We have investigated the nature of this damage and its repairability. When islets are further incubated for 4 h in fresh medium, the level of cytokine-induced strand breakage remains constant.

Antioxidant enzyme activity and mRNA expression in the islets of Langerhans from the BB/S rat model of type 1 diabetes and an insulin-producing cell line.

It has been proposed that low activities of antioxidant enzymes in pancreatic beta cells may increase their susceptibility to autoimmune attack. We have therefore used the spontaneously diabetic BB/S rat model of type 1 diabetes to compare islet catalase and superoxide dismutase activities in diabetes-prone and diabetes-resistant animals. In parallel studies, we employed the RINm5F beta cell line as a model system (previously validated) to investigate whether regulation of antioxidant enzyme activity by inflammatory mediators (cytokines, nitric oxide) occurs at the gene or protein expression level.