AIM:To investigate the in vivo effect of atrial natriureticpeptide(ANP)and its signaling pathway during ortho-topic rat liver transplantation.METHODS:Rats were infused with NaCl,ANP(5 μg/kg),wortmannin(WM,16 μg/kg),...AIM:To investigate the in vivo effect of atrial natriureticpeptide(ANP)and its signaling pathway during ortho-topic rat liver transplantation.METHODS:Rats were infused with NaCl,ANP(5 μg/kg),wortmannin(WM,16 μg/kg),or a combination ofboth for 20 min.Livers were stored in UW solution(4°C)for 24 h,transplanted and reperfused.Apoptosis wasexamined by caspase-3 activity and TUNEL staining.Phosphorylation of Akt and Bad was visualized by West-ern blotting and phospho-Akt-localization by confocalmicroscopy.RESULTS:ANP-pretreatment decreased caspase-3activity and TUNEL-positive cells after cold ischemia,indicating antiapoptotic effects of ANP in vivo.The an-tiapoptotic signaling of ANP was most likely caused byphosphorylation of Akt and Bad,since pretreatment withPI 3-kinase inhibitor WM abrogated the ANP-inducedreduction of caspase-3 activity.Interestingly,analysis ofliver tissue by confocal microscopy showed translocationof phosphorylated Akt to the plasma membrane of hepa-tocytes evoked by ANP.CONCLUSION:ANP activates the PI-3-kinase pathwayin the liver in vivo leading to phosphorylation of Bad, an event triggering antiapoptotic signaling cascade inischemic liver.展开更多
AIM:To investigate the effects of intravenous administration of the antioxidant glutathione (GSH) on reperfusion injury following liver transplantation.METHODS:Livers of male Lewis rats were transplanted after 24 h of...AIM:To investigate the effects of intravenous administration of the antioxidant glutathione (GSH) on reperfusion injury following liver transplantation.METHODS:Livers of male Lewis rats were transplanted after 24 h of hypothermic preservation in University of Wisconsin solution in a syngeneic setting. During a 2-h reperfusion period either saline (controls,n=8) or GSH (50 or 100μmol/(h·kg),n=5 each) was continuously administered via the jugular vein.RESULTS:Two hours after starting reperfusion plasma ALT increased to 1 457±281U/L (mean±SE) in controls but to only 908_+187 U/L (P<0.05) in animals treated with 100μmol GSH/(h·kg).No protection was conveyed by 50μmol GSH/(h·kg).Cytoprotection was confirmed by morphological findings on electron microscopy:GSH treatment prevented detachment of sinusoidal endothelial cells (SECs) as well as loss of microvilli and mitochondrial swelling of hepatocytes. Accordingly, postischemic bile flow increased 2-fold. Intravital fluorescence microscopy revealed a nearly complete restoration of sinusoidal blood flow and a significant reduction of leukocyte adherence to sinusoids and postsinusoidal venules. Following infusion of 50μmol and 100 μmol GSH/(h·kg),plasma GSH increased to 65±7mol/L and 97±18μmol/L,but to only 20±3mol/L in untreated recipients.Furthermore, plasma glutathione disulfide (GSSG) increased to 7.5±1.0mol/L in animals treated with 100μmol/(h·kg) GSH but infusion of 50μmol GSH/(h·kg) did not raise levels of untreated controls (1.8±0.5mol/L vs 2.2±0.2mol/L).CONCLUSION:Plasma GSH levels above a critical level may act as a “sink” for ROS produced in the hepatic vasculature during reperfusion of liver grafts.Therefore, GSH can be considered a candidate antioxidant for the prevention of reperfusion injury after liver transplantation, in particular since it has a low toxicity in humans.展开更多
Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused ...Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused on the epigenetic control of transcriptional processes, especially of tumor suppressor genes,by interfering with the acetylation status of nuclear histone proteins,hence the name histone deacetylase inhibitors was coined.Yet,this view could not explain the high specificity for tumor cells and recent evidence now suggests that non-histone proteins represent major targets for protein deacetylase inhibitors and that the post-translational modification of the acetylome is involved in various cellular processes of differentiation,survival and cell death induction.展开更多
Liver regeneration after major surgery may activate occult micrometastases and facilitate tumor growth,leading to liver tumor recurrence.Molecular changes during liver regeneration can provide a microenvironment that ...Liver regeneration after major surgery may activate occult micrometastases and facilitate tumor growth,leading to liver tumor recurrence.Molecular changes during liver regeneration can provide a microenvironment that stimulates intrahepatic tumor propagation through alterations in cellular signaling pathways,where activation and proliferation of mature hepatocytes,hepatic progenitor cells,non-parenchymal liver cells might favor both liver regeneration and tumor growth.This review highlights recent advances of tumor growth and development in the regenerating liver,possible mechanisms and clinical implications.展开更多
The overall survival for patients with advanced hepatocellular carcinoma(HCC)is still limited.Although the multi-kinase inhibitor sorafenib has recently been approved for this disease,response rates are still low and ...The overall survival for patients with advanced hepatocellular carcinoma(HCC)is still limited.Although the multi-kinase inhibitor sorafenib has recently been approved for this disease,response rates are still low and patients often face dose-limiting toxicities which lead to a reduction in prognosis and treatment success.We here report a patient with metastasized HCC who shows a sustained response for more than 30 mo to sorafenib therapy after failure of a first line therapy with gemcitabine,oxaliplatin and bevacizumab.展开更多
AIM To investigate viability assessment of segmental small bowel ischemia/reperfusion in a porcine model.METHODS In 15 pigs, five or six 30-cm segments of jejunum were simultaneously made ischemic by clamping the mese...AIM To investigate viability assessment of segmental small bowel ischemia/reperfusion in a porcine model.METHODS In 15 pigs, five or six 30-cm segments of jejunum were simultaneously made ischemic by clamping the mesenteric arteries and veins for 1 to 16 h. Reperfusion was initiated after different intervals of ischemia(1-8 h) and subsequently monitored for 5-15 h. The intestinal segments were regularly photographed and assessed visually and by palpation. Intraluminal lactate and glycerol concentrations were measured by microdialysis, and samples were collected for light microscopy and transmission electron microscopy. The histological changes were described and graded.RESULTS Using light microscopy, the jejunum was considered as viable until 6 h of ischemia, while with transmission electron microscopy the ischemic muscularis propria was considered viable until 5 h of ischemia. However, following ≥ 1 h of reperfusion, only segments that had been ischemic for ≤ 3 h appeared viable, suggesting a possible upper limit for viability in the porcine mesenteric occlusion model. Although intraluminal microdialysis allowed us to closely monitor the onset and duration of ischemia and the onset of reperfusion, we were unable to find sufficient level of association between tissue viability and metabolic markers to conclude that microdialysis is clinically relevant for viability assessment. Evaluation of color and motility appears to be poor indicators of intestinal viability.CONCLUSION Three hours of total ischemia of the small bowel followed by reperfusion appears to be the upper limit for viability in this porcine mesenteric ischemia model.展开更多
AIM: To determine functional consequences of this activation, whereby we focused on a potential regulation of the hepatocyte cytoskeleton during ischemia and reperfusion.METHODS: For in vivo experiments, animals recei...AIM: To determine functional consequences of this activation, whereby we focused on a potential regulation of the hepatocyte cytoskeleton during ischemia and reperfusion.METHODS: For in vivo experiments, animals received ANP (5 μg/kg) intravenously. In a different experimental setting, isolated rat livers were perfused with KH-buffer ±ANP (200 nmol/L)±SB203580 (2 μmol/L). Liverswere then kept under ischemic conditions for 24 h, and either transplanted or reperfused. Actin, Hsp27, and phosphorylated Hsp27 were determined by Western blotting, p38 MAPK activity by in vitro phosphorylation assay. F-actin distribution was determined by confocal microscopy.RESULTS: We first confirmed that ANP preconditioning leads to an activation of p38 MAPK and observedalterations of the cytoskeleton in hepatocytes of ANPpreconditioned organs. ANP induced an increase of hepatic F-actin after ischemia, which could be prevented by the p38 MAPK inhibitor SB203580 but had no effect on bile flow. After ischemia untreated livers showed a translocation of Hsp27 towards the cytoskeleton and an increase in total Hsp27, whereas ANP preconditioning prohibited translocation but caused an augmentation of Hsp27 phosphorylation. This effect is also mediated via p38 MAPK, since it was abrogated by the p38 MAPK inhibitor SB203580.CONCLUSION: This study reveals that ANP-mediated p38 MAPK activation leads to changes in hepatocyte cytoskeleton involving an elevation of phosphorylated Hsp27 and thereby for the first time shows functional consequences of ANP-induced hepatic p38 MAPK activation.展开更多
基金Supported by the DFG(FOR 440/1)the Alexander von Humboldt Foundation(A.K.K).
文摘AIM:To investigate the in vivo effect of atrial natriureticpeptide(ANP)and its signaling pathway during ortho-topic rat liver transplantation.METHODS:Rats were infused with NaCl,ANP(5 μg/kg),wortmannin(WM,16 μg/kg),or a combination ofboth for 20 min.Livers were stored in UW solution(4°C)for 24 h,transplanted and reperfused.Apoptosis wasexamined by caspase-3 activity and TUNEL staining.Phosphorylation of Akt and Bad was visualized by West-ern blotting and phospho-Akt-localization by confocalmicroscopy.RESULTS:ANP-pretreatment decreased caspase-3activity and TUNEL-positive cells after cold ischemia,indicating antiapoptotic effects of ANP in vivo.The an-tiapoptotic signaling of ANP was most likely caused byphosphorylation of Akt and Bad,since pretreatment withPI 3-kinase inhibitor WM abrogated the ANP-inducedreduction of caspase-3 activity.Interestingly,analysis ofliver tissue by confocal microscopy showed translocationof phosphorylated Akt to the plasma membrane of hepa-tocytes evoked by ANP.CONCLUSION:ANP activates the PI-3-kinase pathwayin the liver in vivo leading to phosphorylation of Bad, an event triggering antiapoptotic signaling cascade inischemic liver.
基金Supported in part by a grant from the Friedrich-Baur Stiftung,the Muenchener Medizinische Wochenschrift (MMW)the Deutsche Forschungsgemeinschaft (DFG Scha 857/1-1DFG FOR 440-717)
文摘AIM:To investigate the effects of intravenous administration of the antioxidant glutathione (GSH) on reperfusion injury following liver transplantation.METHODS:Livers of male Lewis rats were transplanted after 24 h of hypothermic preservation in University of Wisconsin solution in a syngeneic setting. During a 2-h reperfusion period either saline (controls,n=8) or GSH (50 or 100μmol/(h·kg),n=5 each) was continuously administered via the jugular vein.RESULTS:Two hours after starting reperfusion plasma ALT increased to 1 457±281U/L (mean±SE) in controls but to only 908_+187 U/L (P<0.05) in animals treated with 100μmol GSH/(h·kg).No protection was conveyed by 50μmol GSH/(h·kg).Cytoprotection was confirmed by morphological findings on electron microscopy:GSH treatment prevented detachment of sinusoidal endothelial cells (SECs) as well as loss of microvilli and mitochondrial swelling of hepatocytes. Accordingly, postischemic bile flow increased 2-fold. Intravital fluorescence microscopy revealed a nearly complete restoration of sinusoidal blood flow and a significant reduction of leukocyte adherence to sinusoids and postsinusoidal venules. Following infusion of 50μmol and 100 μmol GSH/(h·kg),plasma GSH increased to 65±7mol/L and 97±18μmol/L,but to only 20±3mol/L in untreated recipients.Furthermore, plasma glutathione disulfide (GSSG) increased to 7.5±1.0mol/L in animals treated with 100μmol/(h·kg) GSH but infusion of 50μmol GSH/(h·kg) did not raise levels of untreated controls (1.8±0.5mol/L vs 2.2±0.2mol/L).CONCLUSION:Plasma GSH levels above a critical level may act as a “sink” for ROS produced in the hepatic vasculature during reperfusion of liver grafts.Therefore, GSH can be considered a candidate antioxidant for the prevention of reperfusion injury after liver transplantation, in particular since it has a low toxicity in humans.
基金Supported by Supported by a Research Grant of the University Medical Center Giessen and Marburg
文摘Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused on the epigenetic control of transcriptional processes, especially of tumor suppressor genes,by interfering with the acetylation status of nuclear histone proteins,hence the name histone deacetylase inhibitors was coined.Yet,this view could not explain the high specificity for tumor cells and recent evidence now suggests that non-histone proteins represent major targets for protein deacetylase inhibitors and that the post-translational modification of the acetylome is involved in various cellular processes of differentiation,survival and cell death induction.
文摘Liver regeneration after major surgery may activate occult micrometastases and facilitate tumor growth,leading to liver tumor recurrence.Molecular changes during liver regeneration can provide a microenvironment that stimulates intrahepatic tumor propagation through alterations in cellular signaling pathways,where activation and proliferation of mature hepatocytes,hepatic progenitor cells,non-parenchymal liver cells might favor both liver regeneration and tumor growth.This review highlights recent advances of tumor growth and development in the regenerating liver,possible mechanisms and clinical implications.
文摘The overall survival for patients with advanced hepatocellular carcinoma(HCC)is still limited.Although the multi-kinase inhibitor sorafenib has recently been approved for this disease,response rates are still low and patients often face dose-limiting toxicities which lead to a reduction in prognosis and treatment success.We here report a patient with metastasized HCC who shows a sustained response for more than 30 mo to sorafenib therapy after failure of a first line therapy with gemcitabine,oxaliplatin and bevacizumab.
基金Supported by the Norwegian Research Council through the Integrisc project number 219819Sensocure AS,Langmyra 11,3185 Skoppum,Norway
文摘AIM To investigate viability assessment of segmental small bowel ischemia/reperfusion in a porcine model.METHODS In 15 pigs, five or six 30-cm segments of jejunum were simultaneously made ischemic by clamping the mesenteric arteries and veins for 1 to 16 h. Reperfusion was initiated after different intervals of ischemia(1-8 h) and subsequently monitored for 5-15 h. The intestinal segments were regularly photographed and assessed visually and by palpation. Intraluminal lactate and glycerol concentrations were measured by microdialysis, and samples were collected for light microscopy and transmission electron microscopy. The histological changes were described and graded.RESULTS Using light microscopy, the jejunum was considered as viable until 6 h of ischemia, while with transmission electron microscopy the ischemic muscularis propria was considered viable until 5 h of ischemia. However, following ≥ 1 h of reperfusion, only segments that had been ischemic for ≤ 3 h appeared viable, suggesting a possible upper limit for viability in the porcine mesenteric occlusion model. Although intraluminal microdialysis allowed us to closely monitor the onset and duration of ischemia and the onset of reperfusion, we were unable to find sufficient level of association between tissue viability and metabolic markers to conclude that microdialysis is clinically relevant for viability assessment. Evaluation of color and motility appears to be poor indicators of intestinal viability.CONCLUSION Three hours of total ischemia of the small bowel followed by reperfusion appears to be the upper limit for viability in this porcine mesenteric ischemia model.
基金Supported by the Deutsche Forschungsgemeinschaft, DFG-FOR 440/1. M.K. was supported by the LMU Munich, grant GVBI.S.527
文摘AIM: To determine functional consequences of this activation, whereby we focused on a potential regulation of the hepatocyte cytoskeleton during ischemia and reperfusion.METHODS: For in vivo experiments, animals received ANP (5 μg/kg) intravenously. In a different experimental setting, isolated rat livers were perfused with KH-buffer ±ANP (200 nmol/L)±SB203580 (2 μmol/L). Liverswere then kept under ischemic conditions for 24 h, and either transplanted or reperfused. Actin, Hsp27, and phosphorylated Hsp27 were determined by Western blotting, p38 MAPK activity by in vitro phosphorylation assay. F-actin distribution was determined by confocal microscopy.RESULTS: We first confirmed that ANP preconditioning leads to an activation of p38 MAPK and observedalterations of the cytoskeleton in hepatocytes of ANPpreconditioned organs. ANP induced an increase of hepatic F-actin after ischemia, which could be prevented by the p38 MAPK inhibitor SB203580 but had no effect on bile flow. After ischemia untreated livers showed a translocation of Hsp27 towards the cytoskeleton and an increase in total Hsp27, whereas ANP preconditioning prohibited translocation but caused an augmentation of Hsp27 phosphorylation. This effect is also mediated via p38 MAPK, since it was abrogated by the p38 MAPK inhibitor SB203580.CONCLUSION: This study reveals that ANP-mediated p38 MAPK activation leads to changes in hepatocyte cytoskeleton involving an elevation of phosphorylated Hsp27 and thereby for the first time shows functional consequences of ANP-induced hepatic p38 MAPK activation.
