L Bühler

University of Geneva, Genève, Geneva, Switzerland

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Publications (182)463.67 Total impact

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    ABSTRACT: AIM: To study the safety of epidural anesthesia (EA), its effect on pancreatic perfusion and the outcome of patients with acute pancreatitis (AP). METHODS: From 2005 to August 2010, patients with predicted severe AP [Ranson score ≥ 2, C-reactive protein > 100 or necrosis on computed tomography (CT)] were prospectively randomized to either a group receiving EA or a control group treated by patient controlled intravenous analgesia. Pain management was evaluated in the two groups every eight hours using the visual analog pain scale (VAS). Parameters for clinical severity such as length of hospital stay, use of antibiotics, admission to the intensive care unit, radiological/clinical complications and the need for surgical necrosectomy including biochemical data were recorded. A CT scan using a perfusion protocol was performed on admission and at 72 h to evaluate pancreatic blood flow. A significant variation in blood flow was defined as a 20% difference in pancreatic perfusion between admission and 72 h and was measured in the head, body and tail of the pancreas. RESULTS: We enrolled 35 patients. Thirteen were randomized to the EA group and 22 to the control group. There were no differences in demographic characteristics between the two groups. The Balthazar radiological severity score on admission was higher in the EA group than in the control group (mean score 4.15 ± 2.54 vs 3.38 ± 1.75, respectively, P = 0.347) and the median Ranson scores were 3.4 and 2.7 respectively (P = NS). The median duration of EA was 5.7 d, and no complications of the epidural procedure were reported. An improvement in perfusion of the pancreas was observed in 13/30 (43%) of measurements in the EA group vs 2/27 (7%) in the control group (P = 0.0025). Necrosectomy was performed in 1/13 patients in the EA group vs 4/22 patients in the control group (P = 0.63). The VAS improved during the first ten days in the EA group compared to the control group (0.2 vs 2.33, P = 0.034 at 10 d). Length of stay and mortality were not statistically different between the 2 groups (26 d vs 30 d, P = 0.65, and 0% for both respectively). CONCLUSION: Our study demonstrates that EA increases arterial perfusion of the pancreas and improves the clinical outcome of patients with AP.
    Full-text · Article · Nov 2015 · World Journal of Gastroenterology
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    Full-text · Article · Oct 2015 · Journal of Hepatology
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    ABSTRACT: Platelets are involved in the early phases of liver regeneration. Moreover, platelet transfusion and thrombocytosis were recently shown to enhance hepatocyte proliferation. However, the precise mechanisms remain elusive. This review discusses the latest updates regarding the mechanisms by which platelets stimulate liver regeneration, focusing on their interactions with liver sinusoidal endothelial cells and on their fate within the liver. Following liver injury, platelets are recruited to and trapped within the liver, where they adhere to the endothelium. Subsequent platelet activation results in the release of platelet granules, which stimulate hepatocyte proliferation through activation of the Akt and ERK1/2 signalling pathways. Platelets activate liver sinusoidal endothelial cells, leading to the secretion of growth factors, such as interleukin-6. Finally, liver sinusoidal cells and hepatocytes can also internalize platelets, but the effects of this alternate process on liver regeneration remain to be explored. A better understanding of the mechanisms by which platelets stimulate liver regeneration could lead to improvement in post-operative organ function and allow hepatectomies of a greater extent to be performed.
    Full-text · Article · Oct 2015 · Journal of Hepatology
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    ABSTRACT: The treatment of acute liver failure, a condition with high mortality, comprises optimal clinical care, and in severe cases liver transplantation. However, there are limitations in availability of organ donors. Hepatocyte transplantation is a promising alternative to fill the medical need, in particular the bridge-to-transplant, and as source porcine donors are proposed. In this approach, cell encapsulation is proposed to eliminate or reduce immunosuppression. Besides patients with acute liver failure, patients with alcoholic hepatitis who are unresponsive to a short course of corticosteroids are a target for hepatocyte transplantation. In this review we present an overview of the innate immune barriers in hepatocyte xenotransplantation, including the role of complement and natural antibodies; the role of phagocytic cells and ligands like CD47 in the regulation of phagocytic cells; and the role of Natural Killer cells. We present also some illustrations of physiological species incompatibilities in hepatocyte xenotransplantation, such as incompatibilities in the coagulation system. An overview of the methodology for cell microencapsulation is presented, followed by proof-of-concept studies in rodent and nonhuman primate models of fulminant liver failure: these studies document the efficacy of microencapsulated porcine hepatocytes which warrants progress towards clinical application. Lastly, we present an outline of a provisional clinical trial, that upon completion of preclinical work could start within the upcoming 2-3 years.
    Full-text · Article · Sep 2015 · International Journal of Surgery (London, England)
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    Full-text · Article · Aug 2015 · Journal of Hepatology
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    ABSTRACT: Platelets are involved in the early phases of liver regeneration. Moreover, platelet transfusion and thrombocytosis were recently shown to enhance hepatocyte proliferation. However, the precise mechanisms remain elusive. This review discusses the latest updates regarding the mechanisms by which platelets stimulate liver regeneration, focusing on their interactions with liver sinusoidal endothelial cells and on their fate within the liver. Following liver injury, platelets are recruited to and trapped within the liver, where they adhere to the endothelium. Subsequent platelet activation results in the release of platelet granules, which stimulate hepatocyte proliferation through activation of the Akt and ERK1/2 signalling pathways. Platelets activate liver sinusoidal endothelial cells, leading to the secretion of growth factors, such as interleukin-6. Finally, liver sinusoidal cells and hepatocytes can also internalize platelets, but the effects of this alternate process on liver regeneration remain to be explored. A better understanding of the mechanisms by which platelets stimulate liver regeneration could lead to improvement in post-operative organ function and allow hepatectomies of a greater extent to be performed. Copyright © 2015. Published by Elsevier B.V.
    Full-text · Article · Jul 2015 · Journal of Hepatology
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    ABSTRACT: Spleen gathers numerous functions and plays a critical role in immunity against encapsulated bacteria. Anatomical injuries or physiological spleen dysfunctions can lead to complete (asplenism) or partial (hyposplenism) functional deficits and expose the patient to the risk of fulminant sepsis, as well as to thromboembolic complications. The purpose of this article is to provide the primary care physician with the tools needed to identify functional disorders of the spleen and to prevent their complications. The latest recommendations for antibiotic prophylaxis and immunization are also addressed.
    Full-text · Article · Jun 2015 · Revue médicale suisse
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    ABSTRACT: Two novel types of hydrogel microspheres (MS) are presented. First, one-component microspheres (1-comMS) were produced from sodium alginate (Na-alg) equipped with thiol-functionalized hydroxyl groups. The functionalization pathway included the conversion of Na-alg into tetrabutylammonium alginate, insertion of new carboxyl groups, grafting of α-amine-ω-thiol poly(ethylene glycol), and restoration of the sodium salt. This modification conserves all original carboxyl groups of Na-alg and allows for covalent disulfide bond formation in addition to ionic crosslinking. Second, two-component microspheres (2-comMS) were obtained from a mixture of Na-alg and Na-alg functionalized with cysteamine. This functionalization was achieved by grafting cystamine dihydrochloride on some carboxyl groups followed by the reduction to cysteamine. Using the one-step MS formation process developed for both MS types, very fast ionic gelation with calcium ions conserves the spherical shape of the polymer solution droplets upon extrusion into the gelation bath, while simultaneously occurring slow covalent crosslinking reinforces the hydrogels. The physical properties of both MS types are adjustable by varying the polymer concentration, the degree of grafting, and the mixing ratio. In vitro cell microencapsulation studies confirmed the cytocompatibility of 1-comMS and 2-comMS.
    No preview · Article · May 2015 · Chemistry of Materials
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    ABSTRACT: The expression of plasma proteins changes dramatically as a result of cytokine induction, particularly interleukin-6, and their levels are used as clinical markers of inflammation. miRNAs are important regulators of gene expression and play significant roles in many inflammatory diseases and processes. The interactions between miRNAs and the genes that they regulate during the acute phase response have not been investigated. We examined the effects of IL-6 stimulation on the transcriptome and miRNome of human and mouse primary hepatocytes and the HepG2 cell line. Using an integrated analysis, we identified differentially expressed miRNAs whose seed sequences are significantly enriched in the 3' untranslated regions of differentially expressed genes, many of which are involved in inflammation-related pathways. Our finding that certain miRNAs may de-repress critical acute phase proteins within acute timeframes has important biological and clinical implications. Copyright © 2015. Published by Elsevier Inc.
    Full-text · Article · May 2015 · Genomics

  • No preview · Conference Paper · May 2015
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    ABSTRACT: Background Lymph node involvement in pancreatic adenocarcinoma is a key prognostic factor. Therefore, extending the number of lymph node stations excised in pancreatoduodenectomy may be beneficial to patients with pancreatic adenocarcinoma. This systematic review and meta-analysis examines the outcomes of extended versus standard lymphadenectomy in the published literature.MethodsA meta-analysis of randomized controlled trials (RCTs) comparing extended with standard lymphadenectomy in patients undergoing pancreatoduodenectomy for pancreatic adenocarcinoma was performed. Perioperative outcomes were assessed as pooled odds ratios (ORs) and weighted mean differences. Overall survival was analysed for patients with positive and negative lymph nodes. Results were reported according to the PRISMA statement.ResultsFive RCTs were included, accounting for 724 patients. Extended lymphadenectomy was associated with greater operative time [mean difference: 63 min, 95% confidence interval (CI) 29–96; P < 0.001], increased need for blood transfusions (mean difference: 0.20, 95% CI 0.01–0.30; P = 0.030) and greater postoperative morbidity (OR 1.5, 95% CI 1.25–2.00; P = 0.030), as well as with prolonged diarrhoea after circumferential autonomic nerve dissection around major vessels (OR 12.2, 95% CI 5.3–28.5; P < 0.001). Median survival was similar across the groups in the whole cohort, as well as in subgroups of patients with, respectively, positive and negative lymph node patients.Conclusions Extended lymphadenectomy has a harmful impact on patients undergoing oncological pancreatoduodenectomy compared with standard lymphadenectomy.
    No preview · Article · Apr 2015 · HPB
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    M. Jung · P. Morel · L. Buehler · N. C. Buchs · M. E. Hagen
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    ABSTRACT: Robotic technology commenced to be adopted for the field of general surgery in the 1990s. Since then, the da Vinci surgical system (Intuitive Surgical Inc, Sunnyvale, CA, USA) has remained by far the most commonly used system in this domain. The da Vinci surgical system is a master-slave machine that offers three-dimensional vision, articulated instruments with seven degrees of freedom, and additional software features such as motion scaling and tremor filtration. The specific design allows hand-eye alignment with intuitive control of the minimally invasive instruments. As such, robotic surgery appears technologically superior when compared with laparoscopy by overcoming some of the technical limitations that are imposed on the surgeon by the conventional approach. This article reviews the current literature and the perspective of robotic general surgery. While robotics has been applied to a wide range of general surgery procedures, its precise role in this field remains a subject of further research. Until now, only limited clinical evidence that could establish the use of robotics as the gold standard for procedures of general surgery has been created. While surgical robotics is still in its infancy with multiple novel systems currently under development and clinical trials in progress, the opportunities for this technology appear endless, and robotics should have a lasting impact to the field of general surgery.
    Full-text · Article · Feb 2015 · Langenbeck s Archives of Surgery
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    ABSTRACT: In vivo, bone marrow-derived multipotent mesenchymal stromal cells (MSC) have been identified at sites of tumors, suggesting that specific signals mobilize and activate MSC to migrate into areas surrounding tumors. The signals and migratory mechanisms that guide MSC are not well understood. Here, we investigated migration of human MSC induced by conditioned medium of Huh-7 hepatoma cells (Huh-7 CM). Using a transwell migration system, we showed that human MSC migration was increased in the presence of Huh-7 CM. Using a human cytokine antibody array, we detected increased levels of MIP-1δ and MIP-3α in Huh-7 CM. Recombinant chemokines MIP-1δ and MIP-3α induced MSC migration in 3 out of 5 MSC donors. Anti-MIP-1δ and anti-MIP-3α antibodies added to Huh-7 CM decreased MSC migration, further suggesting that MIP-1δ and MIP-3α were implicated in the Huh-7 CM-induced MSC migration. By real-time PCR, we observed an absence of chemokine receptors CCR2 and CXCR2 and low expression of CCR1, CCR5 and CCR6 in MSC. Expression of these chemokine receptors were not regulated by Huh-7 CM. Furthermore, matrix metalloproteinase 1 (MMP-1) expression was strongly increased in MSC after incubation with Huh-7 CM, suggesting that MSC migration depends on MMP-1 activity. The signaling pathway MAPK/ERK was activated by Huh-7 CM but its inhibition by PD98059 did not impair Huh-7 CM-induced MSC migration. Further, long-term incubation of MSC with MIP-1δ increased α-smooth muscle actin expression, suggesting its implication in the Huh-7 CM-induced evolvement of MSC into myofibroblast. In conclusion, we reported that two inflammatory cytokines, MIP-1δ and MIP-3α are able to increase MSC migration in vitro. These cytokines might be responsible for migration and evolvement of MSC into myofibroblasts in the stromal reaction around tumors.
    No preview · Article · Jan 2015 · Stem Cells and Development
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    ABSTRACT: Background & aims: Mesenchymal stem cell (MSC) transplantation was shown to be effective for the treatment of liver fibrosis, but the mechanisms of action are not yet fully understood. We transplanted encapsulated human MSCs in two mouse models of liver fibrosis to determine the mechanisms behind the protective effect. Methods: Human bone marrow-derived MSCs were microencapsulated in novel alginate-polyethylene glycol microspheres. In vitro, we analyzed the effect of MSC-conditioned medium on the activation of hepatic stellate cells and the viability, proliferation, cytokine secretion, and differentiation capacity of encapsulated MSCs. The level of fibrosis induced by bile duct ligation (BDL) or carbon tetrachloride (CCl4) was assessed after intraperitoneal transplantation of encapsulated MSCs, encapsulated human fibroblasts, and empty microspheres. Results: MSC-conditioned medium inhibited hepatic stellate cell activation and release of MSC secreted anti-apoptotic (IL-6, IGFBP-2) and anti-inflammatory (IL-1Ra) cytokines. Viability, proliferation, and cytokine secretion of microencapsulated MSCs were similar to those of non-encapsulated MSCs. Within the microspheres, MSCs maintained their capacity to differentiate into adipocytes, chondrocytes, and osteocytes. 23% (5/22) of the MSC clones were able to produce anti-inflammatory IL-1Ra in vitro. Microencapsulated MSCs significantly delayed the development of BDL- and CCl4-induced liver fibrosis. Fibroblasts had an intermediate effect against CCl4-induced fibrosis. Mice transplanted with encapsulated MSCs showed lower mRNA levels of collagen type I, whereas levels of matrix metalloproteinase 9 were significantly higher. Human IL-1Ra was detected in the serum of 36% (4/11) of the mice transplanted with microencapsulated MSCs. Conclusions: MSC-derived soluble molecules are responsible for an anti-fibrotic effect in experimental liver fibrosis.
    Full-text · Article · Oct 2014 · Journal of Hepatology
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    ABSTRACT: Advanced surgical procedures have traditionally been a domain of open surgery. However, minimally invasive approaches are evolving with the development of robotic technology which appears capable to overcome technical limitations of conventional laparoscopy. While traditionally perceived as impossible indications for minimally invasive surgery, reports on robotic organ transplantations have surfaced with promising results.
    Full-text · Article · Jun 2014 · Revue médicale suisse
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    ABSTRACT: Regenerative medicine aims to replace a body function or specific cell loss. It includes therapies at the forefront of modem medicine, issuing from translational biomedical research. Transplantation of organs and cells has revolutionized the management of patients for whom medical treatment is a failure. Unfortunately, organ shortage is limiting treatment possibility. As an example, among the 15,000 patients with type I diabetes in Switzerland, only approximately 30 can receive a pancreas or an islet transplant per year. Second example, 500 patients die each year in Switzerland from alcoholic cirrhosis because no treatment is available. Transplantation of islet cells, hepatocytes, mesenchymal stem cells or dopaminergic neurons represents hope fora therapy available for large populations of patients.
    Full-text · Article · Jun 2014 · Revue médicale suisse
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    ABSTRACT: Bone marrow was recently proposed as an alternative and potentially immune-privileged site for pancreatic islet transplantation. The aim of the present study was to assess the survival and rejection mechanisms of free and encapsulated xenogeneic islets transplanted into the medullary cavity of the femur, or under the kidney capsule of streptozotocin-induced diabetic C57BL/6 mice. The median survival of free rat islets transplanted into the bone marrow or under the kidney capsule was 9 and 14 days, respectively, whereas that of free human islets was shorter, 7 days (bone marrow) and 10 days (kidney capsule). Infiltrating CD8+ T cells and redistributed CD4+ T cells, and macrophages were detected around the transplanted islets in bone sections. Recipient mouse splenocytes proliferated in response to donor rat stimulator cells. One month after transplantation under both kidney capsule or into bone marrow, encapsulated rat islets had induced a similar degree of fibrotic reaction and still contained insulin positive cells. In conclusion, we successfully established a small animal model for xenogeneic islet transplantation into the bone marrow. The rejection of xenogeneic islets was associated with local and systemic T cell responses and macrophage recruitment. Although there was no evidence for immune-privilege, the bone marrow may represent a feasible site for encapsulated xenogeneic islet transplantation.
    Full-text · Article · Mar 2014 · PLoS ONE
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    ABSTRACT: Magnetic resonance imaging (MRI) gadolinium-perfusion was applied in simulated Donation after Cardiac Death (DCD) in porcine kidneys to measure intrarenal perfusion. Adenosine triphosphate (ATP) resynthesis during oxygenated hypothermic perfusion was compared to evaluate the "ex vivo organ viability". Adenine nucleotide (AN) was measured by P nuclear magnetic resonance (NMR) spectroscopy. Whereas this latter technique requires sophisticated hardware, gadolinium-perfusion can be realized using any standard proton-MRI scanner. The aim of this work was to establish a correlation between the two methods. Twenty-two porcine kidneys presenting up to 90 min warm ischemia were perfused with oxygenation at 4°C using our magnetic resonance-compatible machine. During the perfusion, P NMR spectroscopy and gadolinium-perfusion sequences were performed. Measures obtained from the gadolinium-perfusion were the speed of elimination of the cortical gadolinium and the presence or absence of a corticomedullar shunt. For ATP resynthesis analysis, P chemical shift imaging was acquired and analyzed. All the kidneys have been submitted to histologic examination. ATP resynthesis was observed in all organs presenting a cortical gadolinium elimination slope of (-) 23° or greater. In organs with lower gadolinium elimination, no AN or only precursors were detected. This study reveals a link between the two methods and demonstrates ex vivo viability in 93% of the analyzed kidneys. Benefits and side effects of both methods are discussed. Oxygenated hypothermic perfusion enables the evaluation of kidneys in DCD simulated situation; gadolinium-perfusion can be introduced into any center equipped with a proton-MRI scanner allowing results superposable with ATP measurement.
    No preview · Article · Jan 2014 · Transplantation
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    ABSTRACT: Minimally invasive approaches for cholecystectomy are evolving in a surge for the best possible clinical outcome for the patients. As one of the most recent developments, a robotic set of instrumentation to be used with the da Vinci Si Surgical System has been developed to overcome some of the technical challenges of manual single incision laparoscopy. From February 2011 to February 2013, all consecutive robotic single site cholecystectomies (RSSC) were prospectively collected in a dedicated database. Demographic, intra- and postoperative data of all patients that underwent RSSC at our institution were analyzed. Data were evaluated for the overall patient cohort as well as after stratification according to patient BMI (body mass index) and surgeon's experience. During the study period, 82 patients underwent robotic single site cholecystectomy at our institution. The dominating preoperative diagnosis was cholelithiasis. Mean overall operative time was 91 min. Intraoperative complications occurred in 2.4% of cases. One conversion to open surgery due to the intraoperative finding of a gallbladder carcinoma was observed and two patients needed an additional laparoscopic trocar. The rate of postoperative complications was 4.9% with a mean length of stay of 2.4 days. No significant differences were observed when comparing results between robotic novices and robotic experts. Patients with higher BMI trended towards longer surgical console and overall operative time, but resulted in similar rates of conversions and complications when compared to normal weight patients. Robotic Single-Site cholecystectomy can be performed safely and effectively with low rates of complications and conversions in patients with differing BMI and by surgeons with varying levels of experience.
    Full-text · Article · Jan 2014 · Journal of Hepato-Biliary-Pancreatic Sciences
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    ABSTRACT: The progress of medical therapies, which rely on the transplantation of microencapsulated living cells, depends on the quality of the encapsulating material. Such material has to be biocompatible, and the microencapsulation process must be simple and not harm the cells. Alginate-poly(ethylene glycol) hybrid microspheres (alg-PEG-M) were produced by combining ionotropic gelation of sodium alginate (Na-alg) using calcium ions with covalent crosslinking of vinyl sulfone-terminated multi-arm poly(ethylene glycol) (PEG-VS). In a one-step microsphere formation process, fast ionotropic gelation yields spherical calcium alginate gel beads, which serve as a matrix for simultaneously but slowly occurring covalent cross-linking of the PEG-VS molecules. The feasibility of cell microencapsulation was studied using primary human foreskin fibroblasts (EDX cells) as a model. The use of cell culture media as polymer solvent, gelation bath, and storage medium did not negatively affect the alg-PEG-M properties. Microencapsulated EDX cells maintained their viability and proliferated. This study demonstrates the feasibility of primary cell microencapsulation within the novel microsphere type alg-PEG-M, serves as reference for future therapy development, and confirms the suitability of EDX cells as control model.
    Full-text · Article · Dec 2013 · Materials

Publication Stats

3k Citations
463.67 Total Impact Points

Institutions

  • 1993-2015
    • University of Geneva
      • • Department of Surgery
      • • Division of Transplantation
      • • Division of Visceral Surgery
      • • Department of Internal Medicine
      • • Division of Nephrology
      • • Department of Pharmacology
      Genève, Geneva, Switzerland
  • 2009
    • Sichuan University
      • Department of General Surgery
      Hua-yang, Sichuan, China
  • 2001-2009
    • Harvard University
      Cambridge, Massachusetts, United States
  • 1997-2008
    • Hôpitaux Universitaires de Genève
      • Département de chirurgie
      Genève, Geneva, Switzerland
  • 2004
    • Nordmark Arzneimittel GmbH & Co.
      Ütersen, Schleswig-Holstein, Germany
  • 2000-2003
    • Harvard Medical School
      • Department of Surgery
      Boston, Massachusetts, United States
  • 1999-2003
    • Massachusetts General Hospital
      • Transplantation Biology Research Center
      Boston, MA, United States