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F Ris

Publications and source records attributed to F Ris.

9 recordsLinked to original sources
PubMed2006

Laparoscopic versus open resection for appendix carcinoid.

BACKGROUND: Since an increasing number of appendectomies are performed via laparoscopy, it is crucial to determine the impact of this approach on appendix carcinoid (AC) outcome. The goal of this study was to compare results of laparoscopic (LAP) versus open (OP) appendectomy for AC according to intend to treat approach. METHODS: A retrospective review (1991-2003) identified 39 patients (median age, 36 years; range, 12-83) treated by laparoscopy (LAP) or laparotomy (OP) for AC in a single institution. Follow-up was complete for all patients (median, 67 months; range, 4-132). RESULTS: Most cases had associated acute appendicitis (64%). Median carcinoid size was 1.1 cm (range, 0.3-5) and 0.4 cm (range, 0.2-3) in the LAP and OP groups, respectively. LAP and OP were performed in 21 (54%) and 18 (46%) patients, respectively. Surgical margins were positive in two patients in the LAP group and one patient in the OP group (p = 0.6). Right colectomies were performed for AC >2 cm in five patients after LAP and in four patients after OP (p = 0.9). Actuarial 5-year survival rates were 100 and 94% in the LAP and OP groups, respectively (p = 0.2). Two patients died in the OP group, one due to metastatic carcinoid and the other due to metachronous colorectal cancer. Synchronous or metachronous colorectal carcinomas developed in six patients (15%). CONCLUSION: Laparoscopic appendectomy is a safe procedure for AC, with carcinologic and long-term results similar to those of conventional appendectomy. Thus, pre- or per-operative suspicion of AC is not a contraindication to LAP. Prognosis of AC appears more dependent on carcinoid malignant potential or associated tumors. Risk for developing colorectal adenocarcinoma is high in AC patients and warrants follow-up of all patients with colonoscopic screening.

Adolescent↗
PubMed2006

An audit of surgical management of gastrointestinal stromal tumours (GIST).

AIM: To analyze GIST outcome after primary resection and to determine if a new grading system could adequately predict there prognosis. METHODS: A retrospective review (1993-2002) identified 80 patients who underwent primary surgical resection for, c-KIT positive, GIST. Follow-up was complete for all patients (median follow-up 42, range 1-132, months). GIST were classified as low or high grade according to the following parameters: size, mitotic rate, mitotic index (MiB1), presence of necrosis, invasion of adjacent structure and presence of metastasis. RESULTS: GIST originated from the stomach (46), small bowel (30), colon and rectum two and mesentery two. At surgery, 94% of cases presented with localized disease and 6% blood born metastasis with or without lymph node invasion. Resections were complete (R0) in 72 cases. R0 resection correlated with prognosis (p<0.01). Sixty GIST were classified as low grade (median follow-up 60 months) and 20 as high grade (median follow-up 27 months). Five-year actuarial survival of patients with low or high grade GIST were of 95 and 21%, respectively, (p<0.001). CONCLUSION: Prognosis of GIST after surgical treatment is influenced by completeness of primary resection and tumour malignant potential. Low grade GIST have an excellent prognosis after surgery alone, while high grade GIST have a high rate of recurrence after primary resection. Adjuvant treatment should be advocated for patient with either high grade GIST or after incomplete primary resection. The presented grading system can reliably predict GIST outcome after primary surgical treatment. Complete surgical resection offers good chance of cure for low grade GIST, while for high grade GIST surgery alone is not sufficient. The presented grading system could be used to identify patients who may benefit of adjuvant treatment with imatinib mesylate after GIST resection.

Adult↗
PubMed2003

Ectopic expression of the beta-cell specific transcription factor Pdx1 inhibits glucagon gene transcription.

AIMS/HYPOTHESIS: The transcription factor Pdx1 is required for the development and differentiation of all pancreatic cells. Beta-cell specific inactivation of Pdx1 in developing or adult mice leads to an increase in glucagon-expressing cells, suggesting that absence of Pdx1could favour glucagon gene expression by a default mechanism. METHOD: We investigated the inhibitory role of Pdx1 on glucagon gene expression in vitro. The glucagonoma cell line InR1G9 was transduced with a Pdx1-encoding lentiviral vector and insulin and glucagon mRNA levels were analysed by northern blot and real-time PCR. To understand the mechanism by which Pdx1 inhibits glucagon gene expression, we studied its effect on glucagon promoter activity in non-islet cells using transient transfections and gel-shift analysis. RESULTS: In glucagonoma cells transduced with a Pdx1-encoding lentiviral vector, insulin gene expression was induced while glucagon mRNA levels were reduced by 50 to 60%. In the heterologous cell line BHK-21, Pdx1 inhibited by 60 to 80% the activation of the alpha-cell specific element G1 conferred by Pax-6 and/or Cdx-2/3. Although Pdx1 could bind three AT-rich motifs within G1, two of which are binding sites for Pax-6 and Cdx-2/3, the affinity of Pdx1 for G1 was much lower as compared to Pax-6. In addition, Pdx1 inhibited Pax-6 mediated activation through G3, to which Pdx1 was unable to bind. Moreover, a mutation impairing DNA binding of Pdx1 had no effect on its inhibition on Cdx-2/3. Since Pdx1 interacts directly with Pax-6 and Cdx-2/3 forming heterodimers, we suggest that Pdx1 inhibits glucagon gene transcription through protein to protein interactions with Pax-6 and Cdx-2/3. CONCLUSION/INTERPRETATION: Cell-specific expression of the glucagon gene can only occur when Pdx1 expression extinguishes from the early alpha cell precursor.

Animals↗
PubMed2002

Impact of integrin-matrix matching and inhibition of apoptosis on the survival of purified human beta-cells in vitro.

AIMS/HYPOTHESIS: Human islet cells survive poorly in culture and are overgrown by non-endocrine cells. The aims of this study were to sort human beta cells and to develop approaches for their improved survival in culture. METHODS: Human islets were infected with recombinant adenovirus expressing green fluorescent protein (GFP) under the control of the rat insulin promoter such that only beta cells expressed GFP. GFP-positive beta cells were sorted by flow cytometry, and expression of select integrins evaluated by RT-PCR. Beta cells were cultured on different extracellular matrices for up to 15 days. Apoptosis was measured by annexin V binding and ELISA. Insulin secretion was measured by ELISA. RESULTS: Sorted beta cells survived less well in culture than unsorted islet cells. This did not appear to be due to adenoviral infection and/or GFP expression. Purified beta cells expressed the integrins alpha 3, alpha 5, alpha 6, alpha V, beta1, but not beta 4. Of the various matrices tested, sorted beta cells attached and spread best on a lawn of lysed human bladder carcinoma cells (5637 cells). However, survival remained poor. Cell death was decreased but not prevented by continued presence of 10 mmol/l nicotinamide and apoptosis decreased by 24 h incubation with 20 micromol/l Z-VAD. Insulin secretion was maintained over 6 days following treatment with both agents. CONCLUSIONS/INTERPRETATION: Purification of human beta cells induces marked apoptosis limiting their function and survival in vitro. This was improved by matching the extracellular matrix to the specific expression of integrins and by addition of nicotinamide and Z-VAD.

Adult↗
PubMed2001

Human islet transplantation network for the treatment of Type I diabetes: first data from the Swiss-French GRAGIL consortium (1999-2000). Groupe de Recherche Rhin Rhĵne Alpes Genève pour la transplantation d'Ilots de Langerhans.

AIMS/HYPOTHESIS: Improvements in islet transplantation require clinical series large enough to implement controlled new strategies. The goal of this study was to demonstrate the feasibility of a multicentre network for islet transplantation in Type I (insulin-dependent) diabetic patients. METHODS: The five centres (Besançon, Geneva, Grenoble, Lyon, Strasbourg) of the GRAGIL network allow pancreas procurement, recipient recruitment, transplantation procedure and follow-up. Islet isolation is, however, performed in one single laboratory (Geneva). Pancreata were procured in each of the five centres and transported to Geneva with an ischaemia time of less than 8 hours. Islets were isolated using a standard automated method. If the islet number was too low for a graft (< 6,000 Islet-equivalent/kg), islets were cultured up to 12 days until another isolation was possible. Islets were transplanted by percutaneous transhepatic intraportal injection. Immunosuppression consisted of cyclosporine, mycophenolate mofetil, steroids and an anti-interleukin 2 receptor antibody. RESULTS: From March 1999 to June 2000, 56 pancreata procurements were performed with an average yield of 234500 islet-equivalent, with 32 preparations over 200000 islet-equivalent. Ten C-peptide negative Type I diabetic patients (5 men and 5 women, median age 44 years, median diabetes duration 29 years) with an established kidney graft (> 6 months) received 9,030 +/- 1,090 islet-equivalent/kg with a median purity of 63 %. The number of pancreata required for each graft was 1 (n = 5) or 2 (n = 5). At the completion of a 12 month follow-up, we observed 0% primary nonfunction, 50% graft survival and 20% insulin-independence. CONCLUSIONS/INTERPRETATION: This study demonstrates the interest and the feasibility of a multicentre collaboration in human islet transplantation.

Adult↗
PubMed2001

NGF-withdrawal induces apoptosis in pancreatic beta cells in vitro.

AIMS/HYPOTHESIS: Using primary cultures of human pancreatic islets, purified human pancreatic beta cells and the mouse beta TC6-F7 cell line, we analysed the expression of nerve growth factor, (NGF/NGF) receptors in beta cells. To investigate whether NGF could sub-serve an autocrine antiapoptotic role in beta cells, we studied the effects of NGF withdrawal using a neutralizing monoclonal anti-NGF antibody. METHODS: The expression of NGF and NGF receptors (gp140(Trk-A) and p75(NTR)) were analysed by RT-PCR and immunofluorescence. Pulse-chase experiments and beta cell/PC12 co-cultures were used to investigate NGF production and secretion from beta cells. Possible apoptosis induced by NGF withdrawal was monitored by phosphatidylserine translocation, nucleosomal formation, DNA laddering and FACS analysis. Involvement of transcription/translation mechanisms were investigated as well as the gp140(Trk-A) required. Finally, signal transduction pathways typically involved in apoptotic mechanisms were analysed by western blot analysis. RESULTS: We show that NGF and both NGF receptors, gp140(Trk-A) and p75(NTR) are expressed in beta cells where NGF is produced and secreted in a biologically active form. NGF-withdrawal induces beta-cell transcription/translation independent apoptosis but mediated by gp140(Trk-A). Analysis of signal transduction pathways revealed that NGF withdrawal inhibits the PI3-K, protein kinase B (AKT), Bad survival pathway and activates c-Jun kinase (JNK) whereas ERKs and p38 mitogen-activated protein kinase (MAPK) are not affected. Moreover, Bcl-XL, but not Bcl-2 protein expression are reduced. CONCLUSION/INTERPRETATION: We suggest that the integrity of the NGF/NGF receptor system and NGF bioavailability participate in controlling beta-cell survival in culture which represents a key issue for improving possibilities for transplantations in the treatment of diabetes.

Animals↗
PubMed2001

Beta cell replacement for the treatment of diabetes.

The replacement of insulin-producing beta cells by islet transplantation can efficiently reverse diabetes. The recent improvements in clinical results were made possible by transplanting higher islet masses and through the introduction of new immunosuppressive protocols that avoid diabetogenicity. The need for alternatives to continuous immunosuppression, and an unlimited source of glucose-sensitive, insulin-secreting tissue, is emerging. In this review we discuss the various key steps in islet transplantation and offer perspectives for future developments in the replacement of insulin-producing beta cells for the treatment of type I diabetes.

Animals↗