Effects of glucagon-like peptide-1 (GLP-1) in RINm5F insulinoma cells. Stimulation of insulin secretion, insulin content, and insulin receptor binding

Glucagon-like peptide-1 (GLP-1) is the major incretin hormone from the distal small intestine which stimulates basal and glucose-induced insulin secretion. Using the rat insulinoma cell line RINm5F (Gazdar et al. 1980) we investigated the effects of GLP-1 on insulin secretion, insulin content, and insulin receptor binding. During a 1 hour incubation, GLP-1 [1 nM] stimulated insulin secretion 2-fold (p < 0.01 vs controls). Incubating RINm5F for 24 h with GLP-1 [1 nM], a 1.6-fold higher cellular insulin content was observed (p < 0.01 vs controls). Moreover, GLP-1 induced a 2-fold higher capacity and a 15-fold higher affinity of 125I-insulin binding on the cell surface (p < 0.01 vs controls). Glucagon, known as a potent stimulator of insulin secretion, yielded a similar effect only in 1,000-fold higher concentrations, whereas the intracellular insulin content as well as insulin receptor binding was not increased. Taken together, in RINm5F insulinoma cells GLP-1 potently stimulates insulin secretion and insulin content, and improves insulin receptor binding.

A randomized multicentre phase II trial comparing adjuvant therapy in patients with interferon alpha-2b and 5-FU alone or in combination with either external radiation treatment and cisplatin (CapRI) or radiation alone regarding event-free survival - CapRI-2

BACKGROUND

The 5-year survival of patients with resected pancreatic adenocarcinoma is still unsatisfying. The ESPAC-1 and the CONKO 001 trial proofed that adjuvant chemotherapy improves 5-year survival significantly from approximately 14% to 21%. In parallel, investigators from the Virginia Mason Clinic reported a 5-year survival rate of 55% in a phase II trial evaluating a combination of adjuvant chemotherapy, immunotherapy and external beam radiation (CapRI-scheme). Two other groups confirmed in phase II trials these results to a certain extent. However, these groups reported severe gastrointestinal toxicity (up to 93% grade 3 or 4 toxicity). In a randomized controlled phase III trial, called CapRI, 110 patients were enrolled from 2004 to 2007 in Germany and Italy to check for reproducibility. Interestingly, much less gastrointestinal toxicity was observed. However, dose-reduction due to haematological side effects had to be performed in nearly all patients. First clinical results are expected for the end of 2009.

METHODS/DESIGN

CapRI-2 is an open, controlled, prospective, randomized, multicentre phase II trial with three parallel arms. A de-escalation of the CapRI-scheme will be tested in two different modifications. Patients in study arm A will be treated as outpatients with the complete CapRI-scheme consisting of cisplatin, Interferon alpha-2b and external beam radiation and three cycles of 5-fluorouracil continuous infusion. In study arm B the first de-escalation will be realised by omitting cisplatin. Next, patients in study arm C will additionally not receive external beam radiation. A total of 135 patients with pathologically confirmed R0 or R1 resected pancreatic adenocarcinoma are planned to be enrolled. Primary endpoint is the comparison of the treatment groups with respect to six-month event-free-survival. An event is defined as grade 3 or grade 4 toxicity, objective tumour recurrence, or death.

DISCUSSION

The aim of this clinical trial is to evaluate de-escalation of the CapRI-scheme. It is hypothesised that removal of cisplatin and radiotherapy will have no significant effect or only a minor impact on the clinical response but result in substantially lower toxicity.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN79802092.

Inotropic, chronotropic and dromotropic effects of prenalterol, a new cardiostimulant drug

Prenalterol (H 133/22) is an adrenergic beta-receptor stimulator which unlike isoproterenol is both orally active and has a long duration of action. The inotropic, chronotropic and dromotropic effects of prenalterol were investigated in pentobarbital anaesthetized dogs. Prenalterol was found to increase left ventricular maximum dP/dt in a dose-dependent manner up to a dose level of 50 micrograms/kg. Additional doses resulted in only small further increases in cardiac contractility. Electrophysiological studies were done to compare the effects of prenalterol and isoproterenol on sinus node and ventricular pacemaker function. Complete AV block was produced by electrocauterization of the His bundle. Prenalterol accelerated both ventricular and sinus node pacemakers at doses up to 50 micrograms/kg. The increase in ventricular rate was greater than the increase in sinus rate following supramaximal inotropic doses of prenalterol yet no ventricular extrasystoles were ever observed. Similar acceleration of the ventricular and sinus node pacemakers were observed by infusion of isoproterenol. Prenalterol and isoproterenol accelerated AV nodal conduction and ventricular conduction but had little effect upon His-Purkinje conduction. Sinus node reset time was abbreviated as was the functional and effective refractory periods of the atrium and AV nodes.

IL-20 receptor 2 signaling down-regulates antigen-specific T cell responses

The recently described cytokines IL-19, IL-20, and IL-24 share structural homology with IL-10 and are therefore classified as members of the IL-10 family of cytokines. Although it has long been speculated that signaling by their heterodimeric receptor complexes (IL-20R1/IL-20R2 and IL-22R/IL-20R2) influences immunological processes, the target cells for this group of cytokines are still unclear. By generating a knockout mouse strain deficient for the common IL-20R beta-chain (IL-20R2), we show that IFN-gamma and IL-2 secretion is significantly elevated after stimulation of IL-20R2-/--deficient CD8 and CD4 T cells with Con A or anti-CD3/CD28 in vitro. IL-10 secretion by activated IL-20R2-/- CD4 cells was diminished. Consistent with our in vitro results, significantly more Ag-specific CD8 IFN-gamma+ and CD4 IFN-gamma+ T cells developed to locally applied DNA vaccines in IL-20R2-deficient mice. In a T cell-dependent model of contact hypersensitivity, IL-20R2 knockout mice were more sensitive to the contact allergen trinitro-chloro-benzene. Thus, IL-20R2 signaling directly regulates CD8 and CD4 T cell answers in vitro and in vivo. For the first time, we provide evidence that IL-19, IL-20, and IL-24 are part of a signaling network that normally down-modulates T cell responses in mice.

The Memory and Attention Test (MAT), an Adaptive, Computer-based Performance Test: Evaluation in Dementia, Mild Cognitive Impairment and Control Subjects

The Memory and Attention Test (MAT), a newly developed, adaptive, computer-based performance test was evaluated in a mixed group of patients with Alzheimer's dementia, subjects with mild cognitive impairment and control subjects at ages from 60 to 89 years.

By means of the MAT, working memory and short-term memory are assessed in the verbal, figural and episodic domains by means of six independent tests individually adjusted to the subjects level of performance on the basis of intermediate results. Sustained attention is also assessed.

For evaluation purposes, well established tests for the respective memory domains were applied. They were the Auditory Verbal and Learning Test (AVLT), the Benton Test, the delayed reproduction of the Taylor Figure, the subtests working memory and logical memory of the Wechsler Memory Scale (WMS) and the Alterskonzentrationstest (AKT), a test analogous to the d2 test, especially suited and standardized for older subjects. Acceptance of the MAT was assessed by means of a questionnaire developed for this purpose.

Computerized testing was commonly well accepted by the subjects. There were highly significant positive correlations between performance in the MAT domains and performance in the respective reference assessments. Thus, the MAT may be a useful diagnostic tool for the assessment of dementia patients. It may be applied for early diagnosis, assessment of progression of disease and demonstration of treatment effects, particularly for disease-modifying treatments in Alzheimer's disease. Standardization relating to age and and education as well as the provision of versions in various languages are under way.

[Quality of undergraduate, graduate and continuing medical education]

There are only a few studies exploring the quality of undergraduate, graduate and continuing medical education, and there is no systematic approach to evaluating the different spheres of competence--knowledge, medical skills and attitudes. Medical state examination results are not appropriate for assessing the quality of medical education. The implementation of statutory continuing medical education requires quality assurance of its contents, which so far has not been implemented. In the majority of hospitals there is a lack graduate medical education programmes. Future challenges that have to be addressed include important problem areas such as standardized evaluation, recruitment of qualified junior researchers, dealing with the Bologna process, teaching the teachers, quality assurance in continuing medical education and lifelong learning. Since a correlation must be assumed between poor knowledge of the quality of undergraduate, graduate and continuing medical education and the quality of this education itself, we need to close the gap of knowledge relating to the quality of medical education.

Strongyloides stercoralis: a rare cause of obstructive duodenal stenosis

BACKGROUND

Strongyloidiasis is a rare helminthic infection in Europe, and it may cause duodenal obstruction.

METHODS

We report a patient who was admitted to our Medical Department with nausea and repeated vomiting since 10 years until food intake became impossible. Subsequent investigations revealed a duodenal obstruction at the upper third of the duodenum, as well as enterocolitis of the terminal ileum with eosinophils dispersed throughout the mucosa. Since food intake was still not possible after treatment with a course of i.v. PPI and prokinetic applications, we decided to perform a resection of the upper duodenum with Y-Roux reconstruction.

RESULTS

The histopathological examination of the resected specimen revealed strongyloidiasis.

CONCLUSION

Parasite infections such as strongyloidiasis represent a rare differential diagnosis of duodenal obstruction especially if patients originate from endemic regions.

Bones and Crohn's: estradiol deficiency in men with Crohn's disease is not associated with reduced bone mineral density

Background

Reduced bone mineral density (BMD) and osteoporosis are frequent in Crohn's disease (CD), but the underlying mechanisms are still not fully understood. Deficiency of sex steroids, especially estradiol (E2), is an established risk factor in postmenopausal osteoporosis.

Aim

To assess if hormonal deficiencies in male CD patients are frequent we investigated both, sex steroids, bone density and bone metabolism markers.

Methods

111 male CD patients underwent osteodensitometry (DXA) of the spine (L1–L4). Disease related data were recorded. Disease activity was estimated using Crohn's disease activity index (CDAI). Testosterone (T), dihydrotestosterone (DHT), estradiol (E2), sex hormone binding globulin (SHBG), Osteocalcin and carboxyterminal cross-linked telopeptids (ICTP) were measured in 111 patients and 99 age-matched controls.

Results

Patients had lower T, E2 and SHBG serum levels (p < 0.001) compared to age-matched controls. E2 deficiency was seen in 30 (27.0%) and T deficiency in 3 (2.7%) patients but only in 5 (5.1%) and 1 (1%) controls. Patients with E2 deficiency had significantly decreased T and DHT serum levels. Use of corticosteroids for 3 of 12 months was associated with lower E2 levels (p < 0.05). Patients with life-time steroids >10 g had lower BMD. 32 (28.8%) patients showed osteoporosis, 55 (49.5%) osteopenia and 24 (21.6%) had normal BMD. Patients with normal or decreased BMD showed no significant difference in their hormonal status. No correlation between markers of bone turnover and sex steroids could be found. ICTP was increased in CD patients (p < 0.001), and patients with osteoporosis had higher ICTP levels than those with normal BMD.

Conclusion

We found an altered hormonal status – i.e. E2 and, to a lesser extent T deficiency – in male CD patients but failed to show an association to bone density or markers of bone turnover. The role of E2 in the negative skeletal balance in males with CD, analogous to E2 deficiency in postmenopausal females, deserves further attention.

Glutamate Receptor Subunit Expression in Primary Enteric Glia Cultures

Excitotoxicity, which is mediated via glutamate receptors, is also a phenomenon of the enteric nervous system. Whether enteric glial cells (EGCs), which resemble astrocytes of the central nervous system, express glutamate receptors and hence are involved in gut excitotoxicity is not yet known. To investigate glutamate receptor subunit expression in EGCs, primary EGC cultures of the myenteric plexus were analyzed by real-time PCR and Western blotting. These studies indeed showed that in EGC cultures, mRNA of the glutamate receptor subunits NR1, NR2A/B, GluR1, GluR3, and GluR5 and the protein bands of the glutamate receptor subunits NR2A/B, GluR1, GluR3, and GluR5 could be detected. Thus, in the enteric nervous system, glutamate receptor subunits are also expressed by EGCs, indicating that these cells might be involved in gut excitotoxicity.

Metabolism in adipose tissue in response to citalopram and trimipramine treatment--an in situ microdialysis study

The intake of antidepressants is often accompanied by weight gain. Antidepressants may influence lipid and carbohydrate metabolism that can result in metabolic changes and obesity. We investigated the effect of citalopram and trimipramine on interstitial glycerol, glucose and lactate concentration and blood flow in subcutaneous adipose tissue of obese subjects by means of the microdialysis technique. In addition, the effect of stimulation with norepinephrine on metabolic response was investigated. Each subject was compared to a control subject matched for BMI and age. Each group comprised 10 subjects. Circulating plasma triglyceride concentrations were higher in drug-treated groups. In subcutaneous adipose tissue, microdialysis experiments revealed a higher and prolonged glycerol release in the presence of norepinephrine, but not under basal conditions. In citalopram treated subjects, basal glucose and lactate concentrations were higher compared with controls or with the trimipramine treated group. Local administration of norepinephrine induced a decrease in glucose levels and an increase in lactate levels, but without significant differences between groups. Local adipose tissue blood flow decreased in control groups following norepinephrine application, but remained constant in the antidepressant groups. In conclusion, citalopram and trimipramine affected glucose and lipid metabolism in adipose tissue and resulted in enhanced release of glycerol and free fatty acids into the circulation.

Polysialylated NCAM represses E-cadherin-mediated cell-cell adhesion in pancreatic tumor cells

BACKGROUND & AIMS

Inhibition of cell-cell adhesion between epithelial cells represents an early step during tumor metastasis. Down-regulation or perturbation of E-cadherin-mediated adherens junctions is an essential requirement in this process.

METHODS

The interaction between polysialylated neural cell adhesion molecule (PSA-NCAM) and the E-cadherin adhesion complex was studied by coimmunoprecipitation assays. The presence of PSA-NCAM was correlated with tumor invasion by using cell-cell aggregation and cell migration assays. The importance of polysialic acid (PSA) in the interaction of NCAM with E-cadherin and inhibition of cell-cell adhesion was confirmed by enzymatic removal of PSA from NCAM and down-regulation of PSA-transferases by siRNA.

RESULTS

Expression of oncogenic K-Ras(V12) in pancreatic carcinoma cells resulted in induction of PSA-NCAM expression and reduced E-cadherin-mediated cellular adhesion. The association of PSA-NCAM with the E-cadherin adhesion complex correlated with decreased cell-cell aggregation and elevated cell migration of pancreatic carcinoma cells. Enzymatic removal of PSA from NCAM or reduction of polysialyltransferase expression led to reduced association between NCAM and E-cadherin and subsequently increased E-cadherin-mediated cell-cell aggregation and reduced cell migration.

CONCLUSIONS

Our data suggest the induction of PSA-NCAM by oncogenic K-Ras as a novel molecular mechanism by which E-cadherin-mediated cellular adhesion is reduced and dissemination of tumor cells is facilitated.

Selective expansion of the beta-cell compartment in the pancreas of keratinocyte growth factor transgenic mice

Epithelial-mesenchymal interactions are essential for growth, differentiation, and regeneration of exocrine and endocrine cells in the pancreas. The keratinocyte growth factor (KGF) is derived from mesenchyme and has been shown to promote epithelial cell differentiation and proliferation in a paracrine fashion. Here, we have examined the effect of ectopic expression of KGF on pancreatic differentiation and proliferation in transgenic mice by using the proximal elastase promoter. KGF transgenic mice were generated following standard procedures and analyzed by histology, morphometry, immunohistochemistry, Western blot analysis, and glucose tolerance testing. In KGF transgenic mice, the number of islets, the average size of islets, and the relation of endocrine to exocrine tissue are increased compared with littermate controls. An expansion of the beta-cell population is responsible for the increase in the endocrine compartment. Ectopic expression of KGF results in proliferation of beta-cells and pancreatic duct cells most likely through activation of the protein kinase B (PKB)/Akt signaling pathway. Glucose tolerance and insulin secretion are impaired in transgenic animals. These results provide evidence that ectopic expression of KGF in acinar cells promotes the expansion of the beta-cell lineage in vivo through activation of the PKB/Akt pathway. Furthermore, the observed phenotype demonstrates that an increase in the beta-cell compartment does not necessarily result in an improved glucose tolerance in vivo.

Pancreatic beta-cells express hepcidin, an iron-uptake regulatory peptide

Body iron is involved in various vital functions. Its uptake in the intestine is regulated by hepcidin, a bioactive peptide originally identified in plasma and urine and subsequently in the liver. In the present study, we provide evidence at the transcriptional and translational levels that hepcidin is also expressed in the pancreas of rat and man. Immunohistochemical studies localized the peptide exclusively to beta-cells of the islets of Langerhans. Immunoelectron microscopical analyses revealed that hepcidin is confined to the insulin-storing beta-cell secretory granules. As demonstrated in insulinoma-derived RINm5F cells, the expression of hepcidin in beta-cells is regulated by iron. Based on the present findings we conclude that pancreatic islets are an additional source of the peptide hepcidin. The localization of this peptide to beta-cells suggests that pancreatic beta-cells may be involved in iron metabolism in addition to their genuine function in blood glucose regulation. In view of the various linked iron/glucose disorders in the pancreas, the present findings may provide an insight into the phenomenology of intriguing mutual relationships between iron and glucose metabolisms.

[A 40-year-old female patient with seronegative autoimmune hepatitis following a newly acquired hepatitis B infection]

We report the case of a 40-year-old female patient admitted at our clinic because of recent onset jaundice and elevated transaminases. Two months before admission the patient had unprotected sexual contact with a potential hepatitis B-infected man. Virological screening performed in our clinic revealed IgM antibodies against hepatitis B virus core protein (anti-HBc-IgM) and elevated HBV-DNA. Our first diagnosis was an acute hepatitis B virus infection. During her stay at our clinic the patient achieved HBe seroconversion and a loss of HBV-DNA. Nevertheless the transaminases remained high and jaundice persisted. The histological examination of the liver biopsy showed interface hepatitis with plasma cells as the characteristic signs of autoimmune hepatitis. On that basis we started an immunosuppressive therapy with prednisolone in parallel with a prophylactic lamivudine therapy and after two weeks there was a complete resolution of jaundice and a normalisation of transaminases. In conclusion, we present a rare case report of an autoimmune hepatitis as a result a newly acquired hepatitis B infection. This case report highlights the relationship between viral infection and autoimmunity within the liver.

Commensal gut flora drives the expansion of proinflammatory CD4 T cells in the colonic lamina propria under normal and inflammatory conditions

We tested in B6 mice whether the local expansion of CD4 T cells producing proinflammatory cytokines including IL-17 (Th17 cells) in the colonic lamina propria (cLP) depends on the commensal microflora. High numbers of CD4 Th17 cells were found in the lamina propria of the ileum and colon but not the duodenum, jejunum, mesenteric lymph nodes, spleen, or liver of specific pathogen-free (SPF) mice. The microflora is required for the accumulation of cytokine (IL-17, IFN-gamma, TNF-alpha, IL-10)-producing CD4 T cells in the cLP because only low numbers of cytokine-producing cLP CD4 T cells were found in syngeneic (age- and sex-matched) germfree mice. The fraction of cLP Th17 cells was higher in (type I and type II) IFN- but not IL-4- or IL-12p40-deficient SPF congenics. cLP CD4 Th17 cells produce IL-17 but not IFN-gamma, TNF-alpha, IL-4, or IL-10. cLP CD4 Th17 cells accumulate locally in colitis induced by adoptive transfer of IFN-gamma+/+ or IFN-gamma-/- CD4 T cells into congenic SPF (but not germfree) RAG-/- hosts. In this colitis model, cLP CD4 T cells that "spontaneously" produce IL-17 progressively increase in number in the inflamed cLP, and increasing serum IL-17 levels appear as the disease progresses. Commensal bacteria-driven, local expansion of cLP CD4 Th17 cells may contribute to the pathogenesis of this inflammatory bowel disease.