Biomedical subjects

Hauke Rensing

Publications and source records attributed to Hauke Rensing.

13 recordsLinked to original sources

PubMed2006

Induction of heme oxygenase-1 and heat shock protein 70 in rat hepatocytes: the role of calcium signaling.

Stress response genes including heat shock proteins are induced under a variety of conditions to confer cellular protection. This study investigated the role of calcium signaling in the induction of two stress response genes, heme oxygenase-1/hsp32 and hsp70, in isolated rat hepatocytes. Both genes were induced by cellular glutathione depletion. This induction could be inhibited by BAPTA-AM. Culturing in a calcium-free medium prevented the induction of hsp70 gene expression after glutathione depletion without affecting heme oxygenase-1 gene expression. Thapsigargin increased the gene expression of heme oxygenase-1 but not that of hsp70. Thapsigargin-induced heme oxygenase-1 induction was completely inhibited by BAPTA-AM. Incubation with the Ca(2+)-ionophore A23187 augmented heme oxygenase-1 (two-fold) and hsp70 (5.2-fold) mRNA levels. Our data suggests a significant role of Ca(2+)-dependent pathways in the induction of the two stress genes. An increase in the cytoplasmic Ca(2+) activity seems to play a key role in the cascade of signaling leading to the induction of the two genes. However, the source of Ca(2+) that fluxes into the cytoplasm seems to be different. Our data provides evidence for a compartmentalization of calcium fluxes, i.e. the Ca(2+) flux from intracellular stores (e.g. the endoplasmic reticulum) plays a major role in the induction of heme oxygenase-1. By contrast, Ca(2+) flux from the extracellular medium seems to be a mechanism initiating the cellular signaling cascade leading to hsp70 gene induction.

Animals↗

PubMed2006

Dobutamine improves liver function after hemorrhagic shock through induction of heme oxygenase-1.

RATIONALE: Induction of heme oxygenase-1 (HO-1) protects the liver against reperfusion injury after hemorrhagic shock. Previous data suggest that the beta(1)-adrenoceptor agonist dobutamine induces HO-1 in hepatocytes. OBJECTIVES: To investigate the functional significance of dobutamine pretreatment for liver function after hemorrhagic shock in vivo. METHODS: Anesthetized rats received either Ringer's (Vehicle/Shock), 10 microg/kg/min of the beta(1)-adrenoceptor agonist dobutamine (Dob/Shock), or 10 microg/kg/min dobutamine and 500 microg/kg/min of the beta(1)-adrenoceptor antagonist esmolol (Dob/Esmolol/Shock) for 6 h. Hemorrhagic shock was induced thereafter (mean arterial pressure, 35 mm Hg for 90 min). Animals were resuscitated with shed blood and Ringer's. In addition, the HO pathway was blocked after dobutamine pretreatment with 10 micromol/kg tin-mesoporphyrin-IX (Dob/SnMP/Shock) or animals received 100 mg/kg of the carbon monoxide donor dichloromethane (DCM/Shock). MEASUREMENTS: Hepatocellular metabolism and liver blood flow were measured by plasma disappearance rate of indocyanine green (PDR(ICG)) as a sensitive marker of liver function. MAIN RESULTS: Pretreatment with dobutamine induced HO-1 in pericentral hepatocytes and improved PDR(ICG) (Vehicle/Shock: 11.7 +/- 8.12%/min vs. Dob/Shock: 19.7 +/- 2.46%/min, p = 0.006). Blockade of the HO pathway after preconditioning and the combined pretreatment with dobutamine and esmolol decreased PDR(ICG) (Dob/SnMP/Shock: 12.6 +/- 4.24%/min, p = 0.011; Dob/Esmolol/Shock: 10.2 +/- 4.34%/min, p = 0.008). Pretreatment with a carbon monoxide donor improved PDR(ICG) (DCM/Shock: 18 +/- 3.19%/min, p = 0.022) compared with Vehicle/Shock. CONCLUSIONS: These results suggest a beta(1)-adrenoceptor-dependent hepatic up-regulation of HO-1 and a better maintained hepatocellular function after hemorrhagic shock in animals pretreated with dobutamine. The improved hepatocellular function may be in part mediated by carbon monoxide because of up-regulation of HO-1. Pretreatment with dobutamine might be a potential means of pharmacologic preconditioning before ischemia-reperfusion of the liver.

Adrenergic beta-Agonists↗

PubMed2006

Does the timing of tracheal intubation based on neuromuscular monitoring decrease laryngeal injury? A randomized, prospective, controlled trial.

Vocal cord injuries (VCI) and postoperative hoarseness (PH) are common complications after general anesthesia. Poor muscle relaxation at the moment of tracheal intubation may result in VCI. There is a large interindividual variation in neuromuscular depression after administration of neuromuscular blocking drugs. Therefore, the optimal individual timing of tracheal intubation based on neuromuscular monitoring (monitoring) may decrease VCI. In this prospective trial, 60 patients were randomized into 2 groups: Monitoring group: tracheal intubation at maximum block based on monitoring after atracurium 0.5 mg/kg and 2-min group: tracheal intubation 2 min after injection of atracurium 0.5 mg/kg. Intubating conditions were evaluated with the Copenhagen score. VCI were examined by stroboscopy before and 24 and 72 h after surgery. PH was assessed at 24, 48, and 72 h after surgery by a standardized interview. Excellent intubating conditions were significantly increased in the monitoring group compared with the 2-min group: 8 versus 2 patients, respectively (P = 0.036). The incidence of PH between the study groups was comparable: 7 (monitoring) versus 8 patients (2-min) (P = 0.860). Similar findings were observed for VCI: 9 versus 5 patients; respectively (P = 0.268); type of VCI: thickening of the vocal cords: 8 (monitoring) versus 5 (2-min) patients (P = 0.423), hematomas: 2 patients in each group (not significant). The present study demonstrated that neuromuscular monitoring improved endotracheal intubating conditions. However, tracheal intubation at maximum intensity of neuromuscular block was not associated with a decrease in vocal cord injuries.

Adult↗

PubMed2005

Insulin prevents liver damage and preserves liver function in lipopolysaccharide-induced endotoxemic rats.

BACKGROUND/AIMS: Liver integrity and function are crucial for survival of patients suffering from trauma, operations or infections. Insulin decreased mortality and prevented the incidence of multi organ failure and infection in critically ill patients. The aim of the present study was to determine whether insulin exerts positive effects on hepatic homeostasis and function during endotoxemia. METHODS: Endotoxemic rats received either saline or insulin. Hepatic morphology and function was determined by measuring the effect of insulin on liver proteins, enzymes, hepatocyte apoptosis and proliferation including caspases-3 and -9 and Bcl-2. Intrahepatic ATP, glucose and lactate concentration were determined by bioluminescence. To determine possible molecular changes the effect of insulin on hepatic cytokine mRNA and gene profile analysis were assessed. RESULTS: Insulin significantly improved hepatic protein synthesis by increasing albumin and decreasing c-reactive protein, P<0.05. Insulin attenuated hepatic damage by decreasing AST and ALT, P<0.05. Improved liver morphology was due to decreased hepatocyte apoptosis along with decreased caspase-3 concentration and increased hepatocyte proliferation along with Bcl-2 concentration, P<0.05. Insulin decreased hepatic IL-1beta, IL-6 and MIF mRNA and improved hepatic glucose metabolism and glycolysis, P<0.05. GeneChip analysis revealed an anti-inflammatory effect of insulin. CONCLUSIONS: Insulin improves hepatic integrity, hepatic glucose metabolism and hepatic function by increasing cell survival and attenuating the hepatic inflammatory response in endotoxemic rats.

Acute-Phase Proteins↗

PubMed2005

Influence of heme-based solutions on stress protein expression and organ failure after hemorrhagic shock.

OBJECTIVE: Hemoglobin-based oxygen carriers (e.g., diaspirin-cross-linked hemoglobin [DCLHb] and hemoglobin glutamer-200 [HbG]) may have potential in the treatment of hemorrhagic shock. The nitric oxide scavenging and direct vasoconstrictive side effects of free hemoglobin of currently available preparations may increase organ injury after shock in contrast to non-oxygen-carrying heme solutions (e.g., hemin arginate [HAR]). However, both classes of substances might induce the protective enzyme heme oxygenase (HO)-1, particularly in the liver. The aim of the study was to assess the role of pretreatment with DCLHb, HbG, or HAR on HO-1 expression and organ injury after hemorrhagic shock. DESIGN: Prospective controlled laboratory study. SETTING: Animal research laboratory at a university hospital. SUBJECTS: Male Sprague-Dawley rats (200-300 g body weight, n = 5-12/group). INTERVENTIONS: Twenty-four hours after different doses of DCLHb, HbG (each 1, 2, or 3 g/kg of body weight), or HAR (5, 25, or 75 mg/kg of body weight), the protein expression of HO-1 and heat shock protein-70 in liver, kidney, heart, lungs, and aorta was determined. Twenty-four hours after pretreatment with DCLHb, HbG, or HAR, rats were subjected to hemorrhage (mean arterial blood pressure, 35-40 mm Hg for 1 or 2 hrs)/resuscitation (5 or 4 hrs, respectively). Animals treated with Ringer's solution (30 mL/kg of body weight) served as controls. In additional experiments, HO activity was blocked with tin mesoporphyrin-IX. MEASUREMENTS AND MAIN RESULTS: DCLHb, HbG, and HAR dose-dependently induced HO-1 protein but not heat shock protein-70. Pretreatment with DCLHb or HbG shortened the onset of decompensation in shock (DCLHb, 40 +/- 11 mins; HbG, 36 +/- 4 mins) compared with vehicle (68 +/- 4 mins, p < .05) and HAR pretreatment (81 +/- 7 mins, p < .05). High doses of DCLHb pretreatment increased mortality (2 hrs of shock, 80%; p < .05 vs. vehicle or HAR). Pretreatment with HAR led to higher shed blood volumes (p < .05) and higher hepatocellular ATP levels (2 hrs of shock, p < .05 vs. DCLHb and HbG). Blockade of HO activity by tin mesoporphyrin-IX abolished the protection mediated by HAR. CONCLUSIONS: Although DCLHb, HbG, and HAR induce HO-1 in the absence of an unspecific stress response, only HAR pretreatment protects against shock-induced organ failure. Although the underlying mechanisms of positive HAR priming are not completely understood, the induction of HO-1 expression and the lack of nitric oxide scavenging through HAR may play an important role.

Animals↗

PubMed2004

Heme oxygenase-1 gene expression in pericentral hepatocytes through beta1-adrenoceptor stimulation.

Induction of heme oxygenase (HO)-1 may confer hepatocellular protection, e.g., in reperfusion injury. Previous reports suggest that intracellular cAMP up-regulates HO-1. The aim of the present study was to assess the role of adrenoceptor agonists as a means to induce HO-1 and to assess molecular mechanisms of HO-1 gene expression by adrenoceptor agonists. Induction of HO-1 in primary cultures of hepatocytes and in rat liver in vivo was assessed by Northern blot, Western blot, and immunohistochemistry. The beta-receptor agonists (+/-)isoproterenol and (-)isoproterenol induced HO-1 in primary cultures of hepatocytes but not the inactive enantiomer (+)isoproterenol. No induction of HO-1 was observed after alpha1, alpha2, beta2, or beta 3 agonists. beta1-Receptor agonists dobutamine and xamoterol induced HO-1 dose dependently, whereas the beta1-receptor antagonist metoprolol attenuated HO-1 induction by beta1-receptor agonists. Furthermore, 8 Br-cAMP and forskolin induced HO-1. Inhibition of protein kinase A (PKA) abolished induction by dobutamine and 8 Br-cAMP. Parallel changes were observed for the transcription factor AP-1. In vivo infusion of dobutamine for 6 h induced HO-1 in rat livers. Immunohistochemical detection of HO-1 revealed a pericentral expression pattern of HO-1 in hepatocytes, i.e., the area at risk for ischemia/reperfusion injury. These results suggest induction of HO-1 by beta1-adrenoceptor agonists via the PKA pathway in hepatocytes, reflecting a potential means for "pharmacological preconditioning."

Adrenergic Agonists↗

PubMed2003

Recovery of hepatocellular ATP and "pericentral apoptosis" after hemorrhage and resuscitation.

Progressive liver dysfunction contributes significantly to the development of multiple organ failure after trauma/hemorrhage. This study tested the relative impact of necrotic and apoptotic cell death in a graded model of hemorrhagic shock (mean arterial blood pressure=35+/-5 mmHg for 1, 2, or 3 h, followed by 2 h, 1 h, or no resuscitation, respectively) in rats. Prolonged periods of hemorrhagic hypotension (3 h) were paralleled by a profound decrease of hepatic ATP levels and occurrence of pericentral necrosis. Resuscitation after shorter periods of hemorrhagic hypotension resulted in restoration of tissue ATP whereas hepatocellular function as assessed by indocyanine green clearance remained depressed (49.9+/-1.6 mL/(min x kg) at baseline, 28.8+/-1.2 mL/(min x kg) after 2 h of resuscitation; P<0.05). Under these conditions, induction of caspase activity and DNA fragmentation were observed in pericentral hepatocytes that could be prevented by the radical scavenger tempol. Pretreatment with z-Val-Ala-Asp(O-methyl)-flouromethylketone prevented de novo expression of caspase-generated cytokeratin 18, DNA fragmentation, and depression of hepatocellular indocyanine green clearance. These data suggest that prolonged low flow/hypoxia induces ATP depletion and pericentral necrosis and restoration of oxygen supply and ATP levels after shorter periods of low flow ischemia propagate programmed cell death or "pericentral apoptosis."

Adenosine Triphosphate↗

PubMed2003

Perflubron emulsion in prolonged hemorrhagic shock: influence on hepatocellular energy metabolism and oxygen-dependent gene expression.

BACKGROUND: Liver dysfunction as a result of impaired oxygen availability frequently occurs following hemorrhage and contributes to delayed mortality. Artificial oxygen carriers may improve oxygen supply to vital organs while avoiding the need for allogeneic transfusion. METHODS: Rats were subjected to hemorrhagic hypotension (mean arterial pressure = 35-40 mmHg for 120 min) and were subsequently resuscitated with (1) stored whole rat blood, (2) pentastarch, or (3) pentastarch combined with perflubron emulsion (PFE; 2.7 or 5.4 g/kg body weight), a second-generation artificial oxygen carrier. Recovery of liver adenosine triphosphate, hepatocellular injury, and expression of glutamine synthetase 1, a gene that is induced by exposure of hepatocytes to low partial pressure of oxygen, were studied at 4 h of resuscitation. RESULTS: Stored whole blood or pentastarch failed to restore liver adenosine triphosphate concentrations after prolonged shock as compared to sham controls and resulted in increased gene expression of glutamine synthetase 1. Addition of 2.7 g PFE/kg restored liver adenosine triphosphate to control, whereas 5.4 g PFE/kg resulted in adenosine triphosphate concentrations significantly above control. Improved hepatocellular oxygen supply was also confirmed by restoration of the physiologic expression pattern of glutamine synthetase 1. Serum enzyme concentrations were highest after resuscitation with stored blood, whereas addition of PFE failed to further decrease enzyme concentrations as compared to pentastarch alone. CONCLUSIONS: Resuscitation with PFE is superior to stored blood or asanguineous resuscitation with respect to restoration of hepatocellular energy metabolism. The improved hepatocellular oxygen availability is reflected in normalization of oxygen-dependent gene expression. However, improved oxygen availability failed to affect early hepatocellular injury.

Acid-Base Equilibrium↗

PubMed2003

Expression pattern and regulation of heme oxygenase-1/heat shock protein 32 in human liver cells.

Heme oxygenase-1 (HO-1) is a stress response protein that is highly inducible under various conditions, such as oxidative or heat stress. The present study investigated expression pattern and regulation of HO-1 in human liver. Expression pattern of HO-1 immunoreactive protein was studied in liver biopsies by immunohistochemistry, revealing constitutive expression in Kupffer cells but not in hepatocytes. HO-1 was, however, inducible in hepatocytes and vascular tissue under pathological conditions, e.g. associated with fatty degeneration or liver malignancies. Regulation of HO-1 gene expression was further studied by Northern blot analysis in HepG2 cells and freshly isolated peripheral blood mononuclear cells as model systems of parenchymal and nonparenchymal liver cell populations, respectively. HO-1 mRNA was inducible in HepG2 cells and mononuclear cells by various agents inducing oxidative stress. However, HO-1 gene expression was not inducible by heat shock. Pyrrolidine dithiocarbamate, an inhibitor of nuclear factor kappaB-dependent gene expression, dose dependently decreased HO-1 mRNA transcripts in human mononuclear cells subjected to oxidative stress while slightly increasing HO-1 gene expression in HepG2 cells. In contrast, HO-1 induction upon oxidative stress was attenuated in HepG2 cells by cycloheximide and dexamethasone. Although activator protein-1 has been reported as the predominant redox-sensitive transcription factor inducing HO-1 expression in murine macrophages, nuclear factor kappaB seems to play a significant role in human mononuclear cells. Our data are consistent with a role for activator protein-1 in HO-1 induction in human HepG2 hepatoma cells. These data suggest a differential regulation of HO-1 gene expression in parenchymal and non-parenchymal human liver cells and may provide a topographic basis for the understanding of the role of the heme oxygenase/carbon monoxide pathway in human liver disease.

Blotting, Northern↗

PubMed2002

Endothelin-1 and heme oxygenase-1 as modulators of sinusoidal tone in the stress-exposed rat liver.

Heme oxygenase (HO)-1 is up-regulated after ischemia/reperfusion and contributes to maintenance of hepatic perfusion and integrity. Blockade of HO-1 leads to an increased portal pressor response in the stress-exposed liver. We tested whether the increase in portal pressure reflects unmasking of a concomitant up-regulation of the vasoconstrictor endothelin (ET)-1. Hemorrhagic shock induced messenger RNAs encoding HO-1 (16-fold) and ET-1 (9-fold) with a similar time course in the liver. At maximum induction of both mediators, rats received either vehicle or the endothelin ET(A/B) antagonist bosentan (10 mg/kg intravenously). Subsequently, the HO pathway was blocked in all animals by tin-protoporphyrin (SnPP)-IX (50 micromol/kg intravenously). Portal and sinusoidal hemodynamics were measured using microflow probes and intravital microscopy, respectively. Blockade of the HO pathway led to a significant increase in portal resistance (sham/SnPP-IX, 0.17 +/- 0.046 mm Hg. min. mL(-1); shock/vehicle/SnPP-IX, 0.57 +/- 0.148 mm Hg. min. mL(-1); P <.05) and a decrease in sinusoids conducting flow (shock/vehicle/SnPP-IX: baseline, 28.3 +/- 0.85 sinusoids/mm; 10 minutes after SnPP-IX, 23.1 +/- 1.09 sinusoids/mm; P <.05). Intravital microscopy showed narrowing of failing sinusoids colocalizing with stellate cells after blockade of the HO pathway. Blockade of ET(A/B) receptors attenuated the increase in portal resistance (shock/bosentan/SnPP-IX, 0.29 +/- 0.051 mm Hg. min. mL(-1)) and prevented sinusoidal perfusion failure (shock/bosentan/SnPP-IX: baseline, 28.2 +/- 0.97 sinusoids/mm; 10 minutes after SnPP-IX, 28.8 +/- 1.18 sinusoids/mm) as well as sinusoidal narrowing. In conclusion, a functional interaction of the up-regulated vasodilatory HO system and the vasoconstrictor ET-1 on the sinusoidal level exists under stress conditions. Both mediator systems affect sinusoidal diameter via direct action on hepatic stellate cells in vivo.

Animals↗

PubMed2002

Hepatic redox regulation of transcription factors activator protein-1 and nuclear factor-kappaB after hemorrhagic shock in vivo.

Ischemia and reperfusion result in a hepatocellular stress gene response, characterized by a zonal heterogeneity with pericentral hepatocytes being the primary target. In the present study, we assessed cell type-specific and zonal pattern of activation of redox-sensitive transcription factors nuclear factor-kappaB (NFkappaB) and activator protein-1 (AP-1) in a graded model of hemorrhage and their modulation by the antioxidants trolox and tempol. Hemorrhagic hypotension (35-40 mm Hg) up to 3 h without subsequent resuscitation led to an only moderate activation of NFkappaB and AP-1. In contrast, fluid resuscitation after 1 or 2 h of hemorrhage induced a profound activation of AP-1 within the first hour of reperfusion. Consistent with a regulation by oxygen free radicals, activation of AP-1 was substantially attenuated by antioxidants. The faint activation of NFkappaB with various intervals of hemorrhage was unaffected by antioxidants and did not exceed activation with sham operation. Immunohistochemistry for the AP-1 subunit c-Jun revealed a predominant expression in nuclei of pericentral and midzonal hepatocytes. These data suggest activation of AP-1 in hepatocytes most susceptible to injury and reprogramming of gene expression in low-flow ischemia. Whereas activation of NFkappaB is weak in this model and is not modulated by either reperfusion or antioxidants, regulation of AP-1 after hemorrhage and subsequent resuscitation seems to depend on oxygen free radical formation because it requires reperfusion and is inhibitable by antioxidants.

Animals↗

PubMed2002

Impact of alloantigens and storage-associated factors on stimulated cytokine response in an in vitro model of blood transfusion.

BACKGROUND: Transfusion of blood may contribute to immunosuppression in major surgery. The authors assessed the impact of alloantigens and storage on function of peripheral blood mononuclear cells cultured in their physiologic environment. METHODS: Blood units (whole blood, packed erythrocytes) were prepared with or without prestorage leukodepletion and stored for 24-26 days. Blood samples were coincubated with allogeneic fresh blood, autologous, or allogeneic stored blood. Endotoxin-stimulated release of tumor necrosis factor-alpha (TNF-alpha) and interleukin 10 (IL-10) was measured after 24 h of culture by enzyme-linked immunosorbent assay. RESULTS: Coincubation with equal amounts of allogeneic fresh blood showed almost no influence on TNF-alpha (-12%, not significant) and IL-10 (+11%, not significant) release. Stored allogeneic whole blood resulted in a significant TNF-alpha depression (-61%) and IL-10 induction (+221%). These effects were diminished but not prevented by prestorage leukodepletion (TNF-alpha -42%, IL-10 +110%) and required the presence of soluble factors (TNF-alpha suppression) and cellular components (IL-10 induction). TNF-alpha decrease and IL-10 increase were in the same order of magnitude (-40%, +134% with, -65%, +314% without leukodepletion) after coincubation with autologous blood. In contrast, allogeneic erythrocytes had only little effects (TNF-alpha -6%, IL-10 +36%) even at this high transfusion equivalent. CONCLUSION: These data suggest that banked whole blood has an immunosuppressive effect that is largely attributable to storage-dependent factors. These factors are partially removed by prestorage leukodepletion, while the contribution of alloantigens is of minor significance. Immunosuppressive effects are least apparent with leukodepleted erythrocytes, suggesting that the presence of plasma during storage is required for the immunosuppressive effect to develop.

Blood Preservation↗

PubMed2002

Monocyte deactivation in severe human sepsis or following cardiopulmonary bypass.

We investigated the specificity for gram-negative stimuli as well as the contribution of signal transduction pathways for leukocyte hyporesponsiveness in sepsis or following cardiopulmonary bypass (CPB). Whole blood of nine patients undergoing CPB and 25 patients with severe sepsis was stimulated ex vivo with LPS (E. coli O111:B4) or with Staphylococcus aureus Cowan strain I (SAC-I) lysate in the absence or presence of inhibitors of protein kinase C (PKC), protein-tyrosine kinase (PTK), or protein-tyrosine phosphatase (PTP). Both toxins stimulated a TNF-alpha response through PTK signaling. Although suppression of the cytokine response was similar for LPS and SAC-I after CPB, it was significantly more pronounced for SAC-I in sepsis. Inhibition of PTP failed to increase TNF-alpha upon LPS, whereas a moderate increase was observed with SAC-I. Impaired TNF-alpha responses occur in sepsis and after CPB. Although this has primarily been reported for gram-negative stimuli, our data suggest that this is even more pronounced for gram-positive stimuli in severe sepsis. Although PTK was the predominant signaling pathway, inhibition of PTP only partially restored the TNF-alpha response to SAC-I. Our results suggest that cellular mechanisms underlying monocyte deactivation are different in sepsis or following CPB and are discriminate for gram-positive and gram-negative toxins.

Adult↗