Impact of moderate exercise on fatty acid oxidation in pancreatic ß-cells and skeletal muscle.

Fatty acids (FA) play a crucial role in glycaemia regulation in healthy and metabolic disorders conditions through various mechanisms. FA oxidation is one of the processes involved in lipid metabolism and can be modulated by exercise. Nowadays, physical activity is known to be an effective strategy for the prevention and treatment of Type 2 Diabetes. Moreover, its intensity, its duration, the sex-gender, the prandial state, exerkines… are as many parameters that can influence glycaemic control. However, the widely debated question is to determine the best type of exercise for patients with metabolic disorders. In this review, we will discuss the impact of exercise intensity, especially moderate activity, on glycaemic control by focussing on FA oxidation in pancreatic ß-cells and skeletal muscle. Finally, thanks to all the recent data, we will determine whether moderate physical activity is a good therapeutic strategy and if FA oxidation represents a target of interest to treat diabetic, obese and insulin-resistant patients.

The RAGE signaling pathway is involved in intestinal inflammation and represents a promising therapeutic target for Inflammatory Bowel Diseases.

Inflammatory Bowel Diseases (IBD) are chronic inflammatory conditions of the intestinal tract. IBD are believed to result from an inappropriate immune response against the intestinal flora in genetically predisposed patients. The precise etiology of these diseases is not fully understood, therefore treatments rely on the dampening of symptoms, essentially inflammation, rather than on the cure of the disease. Despite the availability of biologics, such as anti-TNF antibodies, some patients remain in therapeutic failure and new treatments are thus needed. The multiligand receptor for advanced glycation end-products (RAGE) is a pattern recognition receptor implicated in inflammatory reactions and immune system activation. Here, we investigated the role of RAGE in intestinal inflammation and its potential as a therapeutic target in IBD. We showed that RAGE was upregulated in inflamed tissues from IBD patients compared to controls. Rage-/- mice were less susceptible to intestinal and colonic inflammation development than WT mice. WT mice treated with the RAGE-specific inhibitor FPS-ZM1 experienced less severe enteritis and colitis. We demonstrated that RAGE could induce intestinal inflammation by promoting oxidative stress and endothelial activation which were diminished by FPS-ZM1 treatment. Our results revealed the RAGE signaling pathway as a promising therapeutic target for IBD patients.

Impact of the Type of Continuous Insulin Administration on Metabolism in a Diabetic Rat Model.

Exogenous insulin is the only treatment available for type 1 diabetic patients and is mostly administered by subcutaneous (SC) injection in a basal and bolus scheme using insulin pens (injection) or pumps (preimplanted SC catheter). Some divergence exists between these two modes of administration, since pumps provide better glycaemic control compared to injections in humans. The aim of this study was to compare the impacts of two modes of insulin administration (single injections of long-acting insulin or pump delivery of rapid-acting insulin) at the same dosage (4 IU/200 g/day) on rat metabolism and tissues. The rat weight and blood glucose levels were measured periodically after treatment. Immunostaining for signs of oxidative stress and for macrophages was performed on the liver and omental tissues. The continuous insulin delivery by pumps restored normoglycaemia, which induced the reduction of both reactive oxygen species and macrophage infiltration into the liver and omentum. Injections controlled the glucose levels for only a short period of time and therefore tissue stress and inflammation were elevated. In conclusion, the insulin administration mode has a crucial impact on rat metabolic parameters, which has to be taken into account when studies are designed.

Improvement of islet graft function using liraglutide is correlated with its anti-inflammatory properties.

BACKGROUND AND PURPOSE: Liraglutide improves the metabolic control of diabetic animals after islet transplantation. However, the mechanisms underlying this effect remain unknown. The objective of this study was to evaluate the anti-inflammatory and anti-oxidative properties of liraglutide on rat pancreatic islets in vitro and in vivo. EXPERIMENTAL APPROACH: In vitro, rat islets were incubated with 10 µmol·L-1 liraglutide for 12 and 24 h. Islet viability functionality was assessed. The anti-inflammatory properties of liraglutide were evaluated by measuring CCL2, IL-6 and IL-10 secretion and macrophage chemotaxis. The anti-oxidative effect of liraglutide was evaluated by measuring intracellular ROS and the total anti-oxidative capacity. In vivo, 1000 islets were cultured for 24 h with or without liraglutide and then transplanted into the liver of streptozotocin-induced diabetic Lewis rats with or without injections of liraglutide. Effects of liraglutide on metabolic control were evaluated for 1 month. KEY RESULTS: Islet viability and function were preserved and enhanced with liraglutide treatment. Liraglutide decreased CCL2 and IL-6 secretion and macrophage activation after 12 h of culture, while IL-10 secretion was unchanged. However, intracellular levels of ROS were increased with liraglutide treatment at 12 h. This result was correlated with an increase of anti-oxidative capacity. In vivo, liraglutide decreased macrophage infiltration and reduced fasting blood glucose in transplanted rats. CONCLUSIONS AND IMPLICATIONS: The beneficial effects of liraglutide on pancreatic islets appear to be linked to its anti-inflammatory and anti-oxidative properties. These findings indicated that analogues of glucagon-like peptide-1 could be used to improve graft survival.

Impact of Pancreatic Rat Islet Density on Cell Survival during Hypoxia.

In bioartificial pancreases (BP), the number of islets needed to restore normoglycaemia in the diabetic patient is critical. However, the confinement of a high quantity of islets in a limited space may impact islet survival, particularly in regard to the low oxygen partial pressure (PO2) in such environments. The aim of the present study was to evaluate the impact of islet number in a confined space under hypoxia on cell survival. Rat islets were seeded at three different concentrations (150, 300, and 600 Islet Equivalents (IEQ)/cm(2)) and cultured in normal atmospheric pressure (160 mmHg) as well as hypoxic conditions (15 mmHg) for 24 hours. Cell viability, function, hypoxia-induced changes in gene expression, and cytokine secretion were then assessed. Notably, hypoxia appeared to induce a decrease in viability and increasing islet density exacerbated the observed increase in cellular apoptosis as well as the loss of function. These changes were also associated with an increase in inflammatory gene transcription. Taken together, these data indicate that when a high number of islets are confined to a small space under hypoxia, cell viability and function are significantly impacted. Thus, in order to improve islet survival in this environment during transplantation, oxygenation is of critical importance.

Design, characterisation, and bioefficiency of insulin-chitosan nanoparticles after stabilisation by freeze-drying or cross-linking.

Insulin delivery by oral route would be ideal, but has no effect, due to the harsh conditions of the gastrointestinal tract. Protection of insulin using encapsulation in self-assembled particles is a promising approach. However, the lack of stability of this kind of particles in biological environments induces a low bioavailability of encapsulated insulin after oral administration. The objective of this work was to evaluate the effect of two stabilisation strategies alone or combined, freeze-drying and cross-linking, on insulin-loaded chitosan NPs, and to determine their bioefficiency in vitro and in vivo. NPs were prepared by complex coacervation between insulin and chitosan, stabilised either by cross linking with sodium tripolyphosphate solution (TPP), by freeze-drying or both treatments. In vitro bioefficiency NP uptake was evaluated by flow cytometry on epithelial models (Caco-2/RevHT29MTX (mucus secreting cells)). In vivo, NPs were injected via catheter in the peritoneum or duodenum on insulinopenic rats. Freeze-drying increased in size and charge (+15% vs control 412 ± 7 nm; + 36 ± 0.3 mV) in comparison with cross linking which decreased NP size (-25%) without impacting the NP charge. When combined the consecutive treatments reduced NPs size and increased charges as compared to standard level. Freeze drying is necessary to prevent the destruction of NP in intestinal environment in comparison with no freeze dryed one where 60% of NP were destroyed after 2h. Additionally freeze drying combined with cross linking treatments improved bioefficiency of NP with uptake in cell increased when mucus is present. Combination of both treatment showed a protection of insulin in vivo, with a reduction of glycemia when NPs were administrated. This work showed that the combination of freeze drying and cross linking treatment is necessary to stabilize (freeze-drying) and increase bioefficiency (cross-linking) of self assembled NP in the delivery of insulin in vitro and in vivo.

Impact of an autologous oxygenating matrix culture system on rat islet transplantation outcome.

Disruption of the pancreatic islet environment combined with the decrease in oxygen supply that occurs during isolation leads to poor islet survival. The aim of this study was to validate the benefit of using a plasma-based scaffold supplemented with perfluorodecalin to improve islet transplantation outcome. Rat islets were cultured in three conditions: i) control group, ii) plasma based-matrix (P-matrix), and iii) P-matrix supplemented with emulsified perfluorodecalin. After 24 h culture, matrix/cell contacts (Integrinß1, p-FAK/FAK, p-Akt/Akt), survival (caspase 3, TUNEL, FDA/PI), function, and HIF-1α translocation were assessed. Afterwards, P-matrices were dissolved and the islets were intraportally transplanted. Graft function was monitored for 31 days with glycaemia and C-peptide follow up. Inflammation was assessed by histology (macrophage and granulocyte staining) and thrombin/anti-thrombin complex measurement. Islet survival correlated with an increase in integrin, FAK, and Akt activation in P-matrices and function was maintained. Perfluorodecalin supplementation decreased translocation of HIF-1α in the nucleus and post-transplantation islet structure was better preserved in P-matrices, but a quicker activation of IBMIR resulted in early loss of graft function. "Oxygenating" P-matrices provided a real benefit to islet survival and resistance in vivo. However, intraportal transplantation is not suitable for this kind of culture due to IBMIR; thus, alternative sites must be explored.

Acute enteritis associated with Coxsackievirus A19 in a kidney transplant patient.

Diarrhea is a frequent complication after kidney transplantation, with an incidence rate between 22% and 51%. In many cases, the cause remains unknown. We describe here the first case, to our knowledge, of persistent diarrhea associated with Coxsackievirus A19 (CVA19) in a kidney transplant recipient. The patient was a 46-year-old man who received a deceased-donor kidney. He experienced delayed graft function because of donor kidney donation after circulatory determination of death. Maintenance immunosuppression consisted of low-dose cyclosporine, high-dose mycophenolate mofetil (MMF) (3 g/day), and prednisone (10 mg/day). He had severe diarrhea for 2 weeks associated with acute renal failure. No pathogens were found in the stool cultures. Enterovirus detection was positive by real-time polymerase chain reaction, and sequence analysis found CVA19 (from Enterovirus C group). Area under the curve of MMF was 48 mg.h/L. Because of the persistence of diarrhea, MMF was stopped and replaced by azathioprine. The diarrhea disappeared, but serum creatinine did not return to baseline. CVA19 rarely causes gastroenteritis. This case illustrates that MMF is not always the direct cause of diarrhea, and that new clinical infectious diseases will be detected with the expansion of molecular-based DNA diagnostics.

Dysregulation of alveolar macrophages unleashes dendritic cell-mediated mechanisms of allergic airway inflammation.

Allergic asthma is a chronic inflammatory disorder characterized by eosinophilia and T helper type 2 (Th2) cell activation. However, little information is available on the mechanisms leading to this pathology. We previously showed that alveolar macrophages (AM) from rats with experimental asthma lose their ability to prevent asthma symptoms. To understand the implication of AM in lung immunity, we investigated the influence of AM sensitization status on lung dendritic cell (DC) activation induced by allergen challenge in vivo. Rat sensitized to ovalbumin developed airway inflammation (eosinophils and Th2 cells) and demonstrated myeloid DC (mDC) activation following allergen exposure. The replacement of AM of sensitized animals by AM from naive animals did not affect allergen-triggered eosinophilia but completely abolished lung mDC allergen capture and migration to the lymph nodes, as well as Th2 cell polarization. Moreover, immunosuppressive functions of naive AM occurred in conjunction with low engulfment of allergens but without variation of major histocompatibility complex II and CD23 expression. Interestingly, sensitized AM that were withdrawn from the inflammatory environment regained their immunosuppressive functions when transferred to sensitized rats. Thus, these are the first in vivo evidences showing that dysregulation of AM functions is sufficient to induce DC-triggered allergic response.

[Kimura's disease: an unrecognized cause of adult-onset nephrotic syndrome with minimal change disease]. / La maladie de Kimura: une cause méconnue de syndrome néphrotique à lésions glomérulaires minimes de l'adulte.

Kimura's disease (KD) is an angiolymphoid proliferative disorder of soft tissue with eosinophilia, with a predilection for head and neck regions in young Oriental men. Kidney disease is thought to be rare in KD. About a case of adult-onset nephrotic syndrome with minimal change disease, we comment Kimura's disease and its associated kidney damage. Kimura disease should be suspected and included in the diagnosis of adult-onset nephrotic syndrome with minimal change disease.

Perfluorocarbon emulsions prevent hypoxia of pancreatic ß-cells.

As oxygen carriers, perfluorocarbon emulsions might be useful to decrease hypoxia of pancreatic islets before transplantation. However, their hydrophobicity prevents their homogenisation in culture medium. To increase the surface of contact between islets and Perfluorooctyl bromide (PFOB), and consequently oxygen delivery, we tested effect of a PFOB emulsion in culture medium on ß-cell lines and rat pancreatic islets. RINm5F ß-cell line or pancreatic rat islets were incubated for 3 days in the presence of PFOB emulsion in media (3.5% w/v). Preoxygenation of the medium was performed before culture. Cell viability was assessed by apoptotic markers (Bax and Bcl-2) and by staining (fluoresceine diacetate and propidium iodide). ß-Cell functionality was determined by insulin release during a glucose stimulation test and. Hypoxia markers, HIF-1α and VEGF, were studied at days 1 and 3 using RT-PCR, Western blotting, and ELISA. PFOB emulsions preserved viability and functionality of RINm5F cells with a decrease of HIF-1α and VEGF expression. Islets viability was preserved during 3 days of culture. Secretion of VEGF was higher in untreated control (0.09 ± 0.041 µg VEGF/mg total protein) than in PFOB emulsion incubated islets (0.02 ± 0.19 µg VEGF/mg total protein, n = 4, p < 0.05) at day 1. At day 3, VEGF secretion was increased as compared to day 1 in control (0.23 ± 0.04 µg VEGF/mg total protein) but it was imbalance by the presence of PFOB emulsion (0.09 ± 0.03 µg VEGF/mg total protein, n = 5, p < 0.05). While insulin secretion was maintained in response to a glucose stimulation test until day 3 when islets were incubated in the presence of PFOB emulsion preoxygenated (0.81 ± 0.16 at day 1 vs. 0.75 ± 0.24 at day 3), the ability to secrete insulin in the presence of high glucose concentration was lost in islets controls (0.51 ± 0.18 at day 1 vs. 0.21 ± 0.13 at day 3). Atmospheric oxygen delivery by PFOB emulsion might be sufficient to decrease islets hypoxia. However, to improve islets functionality, overoxygenation is needed. Finally, maintenance of islet viability and functionality for several days after isolation could improve the outcome of islets transplantation.

Instant blood-mediated inflammatory reaction during islet transplantation: the role of Toll-like receptors signaling pathways.

The instant blood-mediated inflammatory reaction (IBMIR) leads to massive destruction of transplanted islets. Islet isolation and time of culture may elicit the release of potent activators of Toll-like receptors (TLRs) signaling pathways during IBMIR. This work sought to evaluate the role of TLR signaling pathways to mediate inflammatory reactions. Isolated rat pancreatic islets were cultured for 12, 24, or 48 hours. Their viability was assessed by fluorescein diacetate/propidium iodide and their functionality, by glucose stimulation tests. Endotoxin levels were quantified using the Limulus Amebocyte Lysate assays. After RNA extraction and reverse transcription, we performed polymerase chain reaction (PCR) arrays. Samples obtained immediately after isolation were defined as controls. Eighty-four genes belonging to the TLR signaling pathways, were compared with control samples. After culture, islets were viable and functional with low endotoxin levels (< 0.1 endotoxin units/mL) showed TLR activation not due to exogenous contamination. Analysis of PCR arrays highlighted significant up-regulation of TLR-2. After 24 hours of culture, TLR-2 was up-regulated to 6.8 ± 0.6-fold (P < .001) compared with controls but decreased to 4.3 ± 1.4-fold after 48 hours. In the same way, expression of myeloid differentiation primary response gene 88 (Myd88) was significantly up-regulated (3.2 ± 0.4-fold [P < .001]) compared with controls. After 12 hours of culture, interleukin-10 gene expression was significantly up-regulated at 11.6 ± 3.7- fold (P < .05), reaching 17.5 ± 8.3 after 24 hours. Finally, the cyclo-oxygenase-2 gene expression was up-regulated to 509 ± 67.1-fold (P < .05) after 12 hours of culture. These data confirmed the implication of TLR signaling pathways in early inflammatory events.

Role of islet culture on angiogenic and inflammatory mechanisms.

Early events hampering islet engraftment may relate to instant blood-mediated inflammatory reaction (IBMIR) and to insufficient islet revascularization inducing ß-cell death. We evaluated the influence of time of culture on angiogenic and inflammatory cellular mechanisms in islet loss in vitro. Rat pancreatic islets cultured for 0, 12, 24, and 48 hours were assessed for functionality using glucose stimulation tests and identification of signaling pathways using polymerase chain reaction (PCR) arrays. Islet functionality decreased significantly immediately. Index of stimulation (IS) was decreased to 2.29 ± 1.05 after 48 hours of culture versus 18.47 ± 4.84 at 0 hours (P < .001). Gene expression studies at 12 hours of culture showed significant overexpression of proinflammatory cytokines and chemokines--interleukin (IL)-6 884.22 ± 282.58 (P < .001) and Cxcl-1 448.09 ± 196.05-fold change (P < .01). Moreover, islets exhibited significant under-expression after 48 hours of genes encoding angiogenic growth factors, such as epidermal growth factor, vascular endothelial growth factor, platelet endothelial cell adhesion molecule 1, a major protein involved in angiogenesis: 0.07 ± 0.02, 0.11 ± 0.08 (P < .001), and 0.17 ± 0.15-fold change (P < .01) respectively. Moreover, tissue inhibitor of metalloproteinases 1, an inhibitor of metallopeptidase, was significantly more over-expressed, namely 54.58 ± 18.08 at 12 hours of culture versus 0.93 ± 0.15/fold change at 0 hours. This study revealed current culture conditions to be deleterious for islet engraftment, possibly due to expression of angiogenic genes and proinflamatory genes during culture.

Improvement of rat islet viability during transplantation: validation of pharmacological approach to induce VEGF overexpression.

Delayed and insufficient revascularization during islet transplantation deprives islets of oxygen and nutrients, resulting in graft failure. Vascular endothelial growth factor (VEGF) could play a critical role in islet revascularization. We aimed to develop pharmacological strategies for VEGF overexpression in pancreatic islets using the iron chelator deferoxamine (DFO), thus avoiding obstacles or safety risks associated with gene therapy. Rat pancreatic islets were infected in vivo using an adenovirus (ADE) encoding human VEGF gene (4.10(8) pfu/pancreas) or were incubated in the presence of DFO (10 µmol/L). In vitro viability, functionality, and the secretion of VEGF were evaluated in islets 1 and 3 days after treatment. Infected islets or islets incubated with DFO were transplanted into the liver of syngenic diabetic rats and the graft efficiency was estimated in vivo by measuring body weight, glycemia, C-peptide secretion, and animal survival over a period of 2 months. DFO induced transient VEGF overexpression over 3 days, whereas infection with ADE resulted in prolonged VEGF overexpression lasting 14 days; however, this was toxic and decreased islet viability and functionality. The in vivo study showed a decrease in rat deaths after the transplantation of islets treated with DFO or ADE compared with the sham and control group. ADE treatment improved body weight and C-peptide levels. Gene therapy and DFO improved metabolic control in diabetic rats after transplantation, but this effect was limited in the presence of DFO. The pharmacological approach is an interesting strategy for improving graft efficiency during transplantation, but this approach needs to be improved with drugs that are more specific.

Extracellular matrix proteins involved in pseudoislets formation.

Extracellular matrix proteins are known to mediate, through integrins, cell adhesion and are involved in a number of cellular processes, including insulin expression and secretion in pancreatic islets. We investigated whether expression of some extracellular matrix proteins were implied in islets-like structure formation, named pseudoislets. For this purpose, we cultured the ß-cell line, RINm5F, during 1, 3, 5 and 7 days of culture on treated or untreated culture plate to form adherent cells or pseudoislets and analysed insulin, collagen IV, fibronectin, laminin 5 and ß1-integrin expression. We observed that insulin expression and secretion were increased during pseudoislets formation. Moreover, we showed by immunohistochemistry an aggregation of insulin secreting cells in the centre of the pseudoislets. Peripheral ß-cells of pseudoislets did not express insulin after 7 days of culture. RT-PCR and immunohistochemistry studies showed a transient expression of type IV collagen in pseudoislets for the first 3 days of culture. Study of fibronectin expression indicated that adherent cells expressed more fibronectin than pseudoislets. In contrast, laminin 5 was more expressed in pseudoislets than in adherent cells. Finally, expression of ß1-integrin was increased in pseudoislets as compared to adherent cells. In conclusion, laminin 5 and collagen IV might be implicated in pseudoislets formation whereas fibronectin might be involved in cell adhesion. These data suggested that extracellular matrix proteins may enhance the function of pseudoislets.

Perfluorocarbons: new tool for islets preservation in vitro.

Pancreatic islet transplantations to treat type 1 diabetes often fail to function because of hypoxia. Perfluorocarbons (PFCs) exhibit a high oxygen solubility coefficient and maintain high oxygen partial pressure for extended times. They also serve as oxygen "reservoirs" for harvested organs in pancreas organ transplantation. Previous studies have shown the PFCs display antiadhesive effects on beta cells. The aim of this study was to evaluate the effects of PFC on islet viability and functionality and on extracellular matrix (ECM) disruption of islets via inhibition of adhesion. Primary cultures of rat islets were incubated for 24 hours in the presence or absence of 3.5% (weight/volume) PFCs in culture media. We studied viability (FDA/PI), stimulation index linked to insulin secretion (ELISA), and expression of insulin and laminin messenger RNAs (mRNAs). Immunostaining was performed on insulin and laminin. Islet viability was similar in the presence or absence of PFCs (about 80%). Stimulation index showed preservation of islet functionality in the presence of PFC (4.9 +/- 0.7) as compared with controls (2.8 +/- 0.5). Moreover, laminin mRNA expression was lower compared with controls (55% of PFC incubated vs control islets). Immunohistochemistry studies showed preservation of ECM inside the islets in the presence of PFCs versus controls at 24 hours after islet isolation. In conclusion, PFCs preserved islet viability and functionality and prevented ECM disruption. PFCs may represent a new tool for islet preservation in vitro.

Influence of rapamycin on rat macrophage viability and chemotaxis toward allogenic pancreatic islet supernates.

The aim of this work was to evaluate the effects of rapamycin on rat macrophage viability and chemotaxis toward allogereic pancreatic islet supernates. Macrophages were isolated from rats by peritoneal lavage at 3 days after intraperitoneal injection of thioglycolate. Macrophage viability was studied after 7 days of culture by Cell Titer assays in the presence of rapamycin at 0.1, 1, and 10 ng/mL (n = 6). After 48 hours of culture, pancreatic rat islet supernates were studied for there chemotactic properties toward freshly isolated macrophages in the presence of rapamycin at 0.1, 1, and 10 ng/mL. Chemotaxis was expressed as a migration index defined as the number of macrophages attracted by the test solution (islet supernate +/- rapamycin)/number of macrophages attracted by the supernate (n = 6). After 3 days of culture, macrophage viability decreased significantly by 22%, 36%, and 32% in the presence of 0.1, 1, and 10 ng/mL rapamycin, respectively (P = .008). Macrophage viability remained stable at about 70% after 7 days of culture. In the presence of islet supernates, macrophage migration increased two-fold compared with those obtained by culture medium. Rapamycin did not influence macrophage migration toward culture medium. However, the drug significantly reduced the migration of macrophages toward islet supernates from 2 +/- 0.6 to 0.9 +/- 0.4, 0.7 +/- 0.3, or 0.8 +/- 0.4 in the presence of 0.1, 1, or 10 ng/mL rapamycin, respectively (P = .04). Rapamycin decreased the survival of cultured rat macrophages and their migration toward allogenic islet supernates. These results suggested that, besides its anti-proliferative effect on T cells, rapamycin reduced macrophage attraction to the graft site.

Overexpression of vascular endothelial growth factor in vitro using deferoxamine: a new drug to increase islet vascularization during transplantation.

During pancreatic islet transplantation, delayed and insufficient revascularization can deprive islets of oxygen and nutrients, resulting in cell death and early graft failure. Deferoxamine (DFO), an iron chelator, increases vascular endothelial growth factor (VEGF) expression in cells. The aim of this work was to study the effect of DFO on beta-cell and pancreatic islet viability as well as VEGF expression. beta-cell lines from rat insulinoma (Rin m5f) and primary cultures of pancreatic islets from Wistar rats were incubated with DFO (10, 100, and 1000 micromol/L). The viability was evaluated using fluorescein diacetate/propidium iodide for dying pancreatic islets and using cell titers for Rin m5f. Expression of VEGF messenger RNA (mRNA) was quantified using reverse transcriptase polymerase chain reaction (RT-PCR). Finally, VEGF secretion was determined using enzyme-linked immunosorbent assays at 1 to 3 days after treatment. The addition of 10 micromol/L of DFO preserved Rin m5F viability at 24 hours after treatment (10 micromol/L; 101.33% +/- 5.66%; n = 7). However, 100 and 1000 micromol/L of DFO induced cell death (68.92% +/- 5.83% and 65.89% +/- 5.83%, respectively; n = 4). In the same way, viability of pancreatic islets in the presence of DFO was preserved. RT-PCR analysis showed stimulation of VEGF mRNA in the presence of 10 micromol/L of DFO in islets at 3 days after culture. Finally, 10 micromol/L of DFO stimulated secretion of VEGF 7.95 +/- 0.84 versus 1.80 +/- 1.10 pg/microg total protein with 10 micromol/L of DFO in rat islets at 3 days after culture, n = 3; P < .001). The use of DFO to stimulate VEGF expression and increase islet vascularization may be a realistic approach to improve islet viability during transplantation.

The structural elucidation of a novel iridoid derivative from Tachiadenus longiflorus (Gentianaceae) using the LSD programme and quantum chemical computations.

Oleanolic acid, scoparone, scopoletin and a novel iridoid derivative, angelone, were isolated from Tachiadenus longiflorus (Gentianaceae). The structure of angelone was determined from NMR data, given as input to the Logic for Structure Determination Programme, and was finally confirmed by comparison of experimental 13C-NMR chemical shifts with those obtained by quantum mechanical calculations.

Investigations of the Malagasy species Tachiadenus longiflorus Grisebach (Gentianaceae): linking chemical finding and traditional usage.

A decoction of the aerial parts of Tachiadenus longiflorus, a Gentianaceae endemic to Madagascar, is drunk to relieve stomach pains and dyspepsia; while a leaf decoction is drunk as a purgative or to relieve gall bladder ailments in folk medicine in Madagascar. The stem and bark have yielded a large amount of the triterpenoid, oleanolic acid, and the coumarins, scoparone and scopoletin. These compounds have been isolated previously from other sources and have shown broad pharmacological properties. We report the possible link between the compounds isolated and the traditional use of Tachiadenus longiflorus.