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Dive into the research topics where Jean-Jacques Gonvers is active.

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Featured researches published by Jean-Jacques Gonvers.


Gastrointestinal Endoscopy | 2005

Impact of colonic cleansing on quality and diagnostic yield of colonoscopy: The European Panel of Appropriateness of Gastrointestinal Endoscopy European multicenter study

Florian Froehlich; Vincent Wietlisbach; Jean-Jacques Gonvers; Bernard Burnand; John-Paul Vader

BACKGROUND The quality of colon cleansing is a major determinant of quality of colonoscopy. To our knowledge, the impact of bowel preparation on the quality of colonoscopy has not been assessed prospectively in a large multicenter study. Therefore, this study assessed the factors that determine colon-cleansing quality and the impact of cleansing quality on the technical performance and diagnostic yield of colonoscopy. METHODS Twenty-one centers from 11 countries participated in this prospective observational study. Colon-cleansing quality was assessed on a 5-point scale and was categorized on 3 levels. The clinical indication for colonoscopy, diagnoses, and technical parameters related to colonoscopy were recorded. RESULTS A total of 5832 patients were included in the study (48.7% men, mean age 57.6 [15.9] years). Cleansing quality was lower in elderly patients and in patients in the hospital. Procedures in poorly prepared patients were longer, more difficult, and more often incomplete. The detection of polyps of any size depended on cleansing quality: odds ratio (OR) 1.73: 95% confidence interval (CI)[1.28, 2.36] for intermediate-quality compared with low-quality preparation; and OR 1.46: 95% CI[1.11, 1.93] for high-quality compared with low-quality preparation. For polyps >10 mm in size, corresponding ORs were 1.0 for low-quality cleansing, OR 1.83: 95% CI[1.11, 3.05] for intermediate-quality cleansing, and OR 1.72: 95% CI[1.11, 2.67] for high-quality cleansing. Cancers were not detected less frequently in the case of poor preparation. CONCLUSIONS Cleansing quality critically determines quality, difficulty, speed, and completeness of colonoscopy, and is lower in hospitalized patients and patients with higher levels of comorbid conditions. The proportion of patients who undergo polypectomy increases with higher cleansing quality, whereas colon cancer detection does not seem to critically depend on the quality of bowel preparation.


Gastroenterology | 1995

Conscious Sedation for Gastroscopy: Patient Tolerance and Cardiorespiratory Parameters

Florian Froehlich; Werner Schwizer; Joël Thorens; Manfred Köhler; Jean-Jacques Gonvers; Michael Fried

BACKGROUND/AIMS Most patients receive conscious sedation for gastroscopy. However, the benefit of the most often used combination of low-dose intravenous midazolam and topical lidocaine on patient tolerance remains poorly defined and has not been shown to outweigh cardiorespiratory risks. To respond to these issues, a randomized, double-blind, placebo-controlled prospective study was performed. METHODS Two hundred outpatients undergoing diagnostic gastroscopy were assigned to receive either (1) midazolam (35 micrograms/kg) and lidocaine spray (100 mg), (2) midazolam and placebo lidocaine, (3) placebo midazolam and lidocaine, or (4) placebo midazolam and placebo lidocaine. RESULTS Tolerance (visual analogue scale, 0-100 points; 0, excellent; 100, unbearable) improved as compared with placebo midazolam and placebo lidocaine by 23 points (95% confidence interval, 15-32) in group 1, 15 points (95% confidence interval, 7-24) in group 2, and 10 points (95% confidence interval, 2-18) in group 3. Increasing age (P < 0.001), low anxiety (P < 0.001), and male sex (P < 0.03), but not amnesia, were associated with better patient tolerance. Oxygen desaturation (< 1 minute) occurred in 8.2% and was not more frequent after midazolam treatment. Hypotension was rare (2.1%), and no adverse outcome occurred. CONCLUSIONS Both low-dose midazolam (35 micrograms/kg) and lidocaine spray have an additive beneficial effect on patients tolerance and rarely induce significant alterations in cardiorespiratory monitoring parameters, thus supporting the widespread use of conscious sedation.


Gastrointestinal Endoscopy | 1997

Sedation and analgesia for colonoscopy : patient tolerance, pain, and cardiorespiratory parameters

Florian Froehlich; Joël Thorens; Werner Schwizer; Martin Preisig; Manfred Köhler; Ron D. Hays; Michael Fried; Jean-Jacques Gonvers

BACKGROUND Colonoscopy is generally performed with the patient sedated and receiving analgesics. However, the benefit of the most often used combination of intravenous midazolam and pethidine on patient tolerance and pain and its cardiorespiratory risk have not been fully defined. METHODS In this double-blind prospective study, 150 outpatients undergoing routine colonoscopy were randomly assigned to receive either (1) low-dose midazolam (35 micrograms/kg) and pethidine (700 micrograms/kg in 48 patients, 500 micrograms/kg in 102 patients), (2) midazolam and placebo pethidine, or (3) pethidine and placebo midazolam. RESULTS Tolerance (visual analog scale, 0 to 100 points: 0 = excellent; 100 = unbearable) did not improve significantly more in group 1 compared with group 2 (7 points; 95% confidence interval [-2-17]) and group 3 (2 points; 95% confidence interval [-7-12]). Similarly, pain was not significantly improved in group 1 as compared with the other groups. Male gender (p < 0.001) and shorter duration of the procedure (p = 0.004), but not amnesia, were associated with better patient tolerance and less pain. Patient satisfaction was similar in all groups. Oxygen desaturation and hypotension occurred in 33% and 11%, respectively, with a similar frequency in all three groups. CONCLUSIONS In this study, the combination of low-dose midazolam and pethidine does not improve patient tolerance and lessen pain during colonoscopy as compared with either drug given alone. When applying low-dose midazolam, oxygen desaturation and hypotension do not occur more often after combined use of both drugs. For the individual patient, sedation and analgesia should be based on the endoscopists clinical judgement.


European Journal of Immunology | 2008

Polyfunctional HCV-specific T-cell responses are associated with effective control of HCV replication

Donatella Ciuffreda; Denis Comte; Matthias Cavassini; Emiliano Giostra; Leo H. Buhler; Monika Perruchoud; Markus H. Heim; Manuel Battegay; Daniel Genné; Beat Mulhaupt; Raffaele Malinverni; Carl Oneta; Enos Bernasconi; Martine Monnat; Andreas Cerny; Christian Chuard; Jan Borovicka; Gilles Mentha; Manuel Pascual; Jean-Jacques Gonvers; Giuseppe Pantaleo; Valérie Dutoit

HCV infection has a severe course of disease in HIV/HCV co‐infection and in liver transplant recipients. However, the mechanisms involved remain unclear. Here, we evaluated functional profiles of HCV‐specific T‐cell responses in 86 HCV mono‐infected patients, 48 HIV/HCV co‐infected patients and 42 liver transplant recipients. IFN‐γ and IL‐2 production and ability of CD4 and CD8 T cells to proliferate were assessed after stimulation with HCV‐derived peptides. We observed that HCV‐specific T‐cell responses were polyfunctional in HCV mono‐infected patients, with presence of proliferating single IL‐2‐, dual IL‐2/IFN‐γ and single IFN‐γ‐producing CD4+ and dual IL‐2/IFN‐γ and single IFN‐γ‐producing CD8+ cells. In contrast, HCV‐specific T‐cell responses had an effector profile in HIV/HCV co‐infected individuals and liver transplant recipients with absence of single IL‐2‐producing HCV‐specific CD4+ and dual IL‐2/IFN‐γ‐producing CD8+ T cells. In addition, HCV‐specific proliferation of CD4+ and CD8+ T cells was severely impaired in HIV/HCV co‐infected patients and liver transplant recipients. Importantly, “only effector” T‐cell responses were associated with significantly higher HCV viral load and more severe liver fibrosis scores. Therefore, the present results suggest that immune‐based mechanisms may contribute to explain the accelerated course of HCV infection in conditions of HIV‐1 co‐infection and liver transplantation.


Endoscopy | 2009

Appropriateness of colonoscopy in Europe (EPAGE II) Screening for colorectal cancer

C. Arditi; Isabelle Peytremann-Bridevaux; Bernard Burnand; V. F. Eckardt; P. Bytzer; L. Agréus; Robert W. Dubois; John-Paul Vader; Florian Froehlich; Valérie Pittet; S. Schusselé Filliettaz; Pascal Juillerat; Jean-Jacques Gonvers

BACKGROUND AND STUDY AIMS To summarize the published literature on assessment of appropriateness of colonoscopy for screening for colorectal cancer (CRC) in asymptomatic individuals without personal history of CRC or polyps, and report appropriateness criteria developed by an expert panel, the 2008 European Panel on the Appropriateness of Gastrointestinal Endoscopy, EPAGE II. METHODS A systematic search of guidelines, systematic reviews, and primary studies regarding colonoscopy for screening for colorectal cancer was performed. The RAND/UCLA Appropriateness Method was applied to develop appropriateness criteria for colonoscopy in these circumstances. RESULTS Available evidence for CRC screening comes from small case-controlled studies, with heterogeneous results, and from indirect evidence from randomized controlled trials (RCTs) on fecal occult blood test (FOBT) screening and studies on flexible sigmoidoscopy screening. Most guidelines recommend screening colonoscopy every 10 years starting at age 50 in average-risk individuals. In individuals with a higher risk of CRC due to family history, there is a consensus that it is appropriate to offer screening colonoscopy at < 50 years. EPAGE II considered screening colonoscopy appropriate above 50 years in average-risk individuals. Panelists deemed screening colonoscopy appropriate for younger patients, with shorter surveillance intervals, where family or personal risk of colorectal cancer is higher. A positive FOBT or the discovery of adenomas at sigmoidoscopy are considered appropriate indications. CONCLUSIONS Despite the lack of evidence based on randomized controlled trials (RCTs), colonoscopy is recommended by most published guidelines and EPAGE II criteria available online (http://www.epage.ch), as a screening option for CRC in individuals at average risk of CRC, and undisputedly as the main screening tool for CRC in individuals at moderate and high risk of CRC.


Digestion | 2005

Extraintestinal Manifestations of Crohn’s Disease

Pascal Juillerat; Christian Mottet; Florian Froehlich; Christian Felley; John-Paul Vader; Bernard Burnand; Jean-Jacques Gonvers; Pierre Michetti

In each case of extraintestinal manifestations of Crohn’s disease, active disease, if present, should be treated to induce remission, which may positively influence the course of most concomitant extraintestinal manifestations. For some extraintestinal manifestations, however, a specific treatment should be introduced. This latter part of disease management will be discussed in this chapter, in particular for pyoderma gangrenosum, uveitis, spondylarthropathy – axial arthropathy – and primary sclerosing cholangitis, which have also been described in quiescent Crohn’s disease. Few new drugs for the treatment of extraintestinal manifestations of Crohn’s disease have been developed in the past and only the role of infliximab has increased in Crohn’s disease-related extraintestinal manifestations. Drugs specifically aimed at this treatment, stemming from a few randomized controlled studies or case series, are sulfasalazine, 5-ASA, corticosteroids, azathioprine or 6-mercaptopurine, methotrexate, infliximab, adalimumab, etanercept and cyclosporine or tacrolimus. Unfortunately, because of the paucity of data in this field, the best evidence presented and discussed in this article for the treatment of these extraintestinal manifestations is extrapolated from patients that for the most part did not suffer from Crohn’s disease.


Journal of Viral Hepatitis | 2006

HCV-related advanced fibrosis/cirrhosis: randomized controlled trial of pegylated interferon alpha-2a and ribavirin.

Beat Helbling; Wolfram Jochum; Ivan Stamenic; Marina Knöpfli; Andreas Cerny; Jan Borovicka; Jean-Jacques Gonvers; Martin Wilhelmi; Sabine Dinges; Beat Müllhaupt; Alicia Esteban; Beat Meyer-Wyss; Eberhard L. Renner

Summary.  In patients with hepatitis C virus (HCV)‐related advanced fibrosis/cirrhosis, 30% of sustained HCV clearance has been reported with pegylated interferon α‐2a (PEG‐IFN) alone, but the efficacy and tolerability of the PEG‐IFN/ribavirin (RBV) combination remain poorly defined. A total of 124 treatment‐naïve patients with biopsy proved HCV‐related advanced fibrosis/cirrhosis (Ishak score F4–F6, Child–Pugh score ≤7) were randomized to 48 weeks of PEG‐IFN (180 μg sc weekly) and standard dose of RBV (1000/1200 mg po daily, STD) or PEG‐IFN (180 μg sc weekly) and low‐dose of RBV (600/800 mg po daily, LOW). Sustained virologic response (SVR) rates with PEG‐IFN/STD RBV (52%) were higher – albeit not significantly – than that with PEG‐IFN/LOW RBV (38%, P = 0.153). In multivariate analysis, genotype 2/3 and a baseline platelet count ≥150 × 109/L were independently associated with SVR. The likelihood of SVR was <7% if viraemia had not declined by ≥2 log or to undetectable levels after 12 weeks. Nine adverse events in the STD RBV and 15 in the LOW RBV group were classified as severe (including two deaths); dose reductions for intolerance were required in 78% and 57% (P = 0.013), and treatment was terminated early in 23% and 27% of patients (P = n.s.). The benefit/risk ratio of treating compensated HCV‐cirrhotics with STD PEG‐IFN/RBV is favourable.


Gastrointestinal Endoscopy | 1997

Overuse of upper gastrointestinal endoscopy in a country with open-access endoscopy: a prospective study in primary care

Florian Froehlich; Bernard Burnand; Isabelle Pache; Jean-Paul Vader; Michael Fried; Catherine Schneider; Jacqueline Kosecoff; Marvin Kolodny; Robert W. Dubois; Robert H. Brook; Jean-Jacques Gonvers

BACKGROUND This prospective observational study was aimed at evaluating the appropriateness of use of upper gastrointestinal endoscopy (UGE) in primary care in a country with open access to and high availability of the procedure. METHODS Outpatients were consecutively included in two clinical settings: Setting A (20 primary care physicians during 4 weeks) and B (university-based outpatient clinic during 3 weeks). In patients undergoing UGE, appropriateness of referral was judged by explicit Swiss criteria developed by the RAND/UCLA panel method. RESULTS Patient visits (8135) were assessed. Six hundred eleven patients complained of upper gastrointestinal symptoms. Physicians decided to perform UGE in 63 of these patients. Twenty-five (40%) of the endoscopies were rated appropriate, 7 (11%) equivocal, and 31 (49%) inappropriate. Overuse of UGE occurred in 5.1% (setting A: 4.7%; setting B:6.5%; p = 0.39) of the patients who presented with upper gastrointestinal symptoms. The decision to perform UGE in previously untreated dyspeptic patients was the most common clinical situation resulting in overuse. CONCLUSIONS Inappropriate use of UGE is high in Switzerland. However, to better reflect primary care decision making, overuse should be related not only to patients referred for a medical test, but also to the number of patients who complain of the symptoms that would be investigated by the procedure.


European Journal of Immunology | 2005

Differences in HCV‐specific T cell responses between chronic HCV infection and HIV/HCV co‐infection

Valérie Dutoit; Donatella Ciuffreda; Denis Comte; Jean-Jacques Gonvers; Giuseppe Pantaleo

Hepatitis C virus (HCV)‐specific CD4+ and CD8+ T cell responses were investigated using a panel of 728 overlapping peptides spanning the whole HCV genome in 47 HCV mono‐infected and 26 HIV/HCV co‐infected individuals using the IFN‐γ ELISPOT assay and flow cytometry. The frequency of HCV‐specific T cell responses was similar (∼40%) in both groups, but the breadth of the T cell responses tended to be reduced in HIV/HCV co‐infected individuals. Of interest, 23 new HCV‐derived epitopes were identified, and CD4+ HCV‐specific T cell responses were detected overall in a proportion similar to CD8+ T cell responses. A tendency towards a dominant CD8+ T cell response was associated with HIV/HCV co‐infection. HCV‐specific CD8+ T cells secreted both IL‐2 and IFN‐γ, although a reduction in the percentage of IL‐2/IFN‐γ‐secreting cells was observed in HIV/HCV co‐infected individuals. The increase in CD4+ T cell counts after antiretroviral therapy in HIV/HCV co‐infected individuals was not associated with restoration of HCV‐specific T cell responses. Altogether, these results provide new insights into the characterization of HCV‐specific T cell responses in HCV mono‐infected and HIV/HCV co‐infected individuals.


Digestion | 2005

Fistulizing Crohn’s Disease

Christian Felley; Christian Mottet; Pascal Juillerat; Florian Froehlich; Bernard Burnand; John-Paul Vader; Pierre Michetti; Jean-Jacques Gonvers

Fistulas are common in Crohn’s disease. A population-based study has shown a cumulative risk of 33% after 10 years and 50% after 20 years. Perianal fistulas were the most common (54%). Medical therapy is the main option for perianal fistula once abscesses, if present, have been drained, and should include antibiotics (both ciprofloxacin and metronidazole) and immunomodulators. Infliximab should be reserved for refractory patients. Surgery is often necessary for internal fistulas.

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