LPS-induced imbalanced expression of hepatic vascular stress genes in cirrhosis: possible mechanism of increased susceptibility to endotoxemia

The Intestinal Microbiota in the Development of Chronic Liver Disease: Current Status

Chronic liver disease (CLD) is a significant global health burden, leading to millions of deaths annually. The gut-liver axis plays a pivotal role in this context, allowing the transport of gut-derived products directly to the liver, as well as biological compounds from the liver to the intestine. The gut microbiota plays a significant role in maintaining the health of the digestive system. A change in gut microbiome composition as seen in dysbiosis is associated with immune dysregulation, altered energy and gut hormone regulation, and increased intestinal permeability, contributing to inflammatory mechanisms and damage to the liver, irrespective of the underlying etiology of CLD. The aim of this review is to present the current knowledge about the composition of the intestinal microbiome in healthy individuals and those with CLD, including the factors that affect this composition, the impact of the altered microbiome on the liver, and the mechanisms by which it occurs. Furthermore, this review analyzes the effects of gut microbiome modulation on the course of CLD, by using pharmacotherapy, nutrition, fecal microbiota transplantation, supplements, and probiotics. This review opens avenues for the translation of knowledge about gut-liver interplay into clinical practice as an additional tool to fight CLD and its complications.

Knockdown of circulating C1 inhibitor induces neurovascular impairment, glial cell activation, neuroinflammation, and behavioral deficits

The cross-talk between blood proteins, immune cells, and brain function involves complex mechanisms. Plasma protein C1 inhibitor (C1INH) is an inhibitor of vascular inflammation that is induced by activation of the kallikrein-kinin system (KKS) and the complement system. Knockout of C1INH was previously correlated with peripheral vascular permeability via the bradykinin pathway, yet there was no evidence of its correlation with blood-brain barrier (BBB) integrity and brain function. In order to understand the effect of plasma C1INH on brain pathology via the vascular system, we knocked down circulating C1INH in wild-type (WT) mice using an antisense oligonucleotide (ASO), without affecting C1INH expression in peripheral immune cells or the brain, and examined brain pathology. Long-term elimination of endogenous C1INH in the plasma induced the activation of the KKS and peritoneal macrophages but did not activate the complement system. Bradykinin pathway proteins were elevated in the periphery and the brain, resulting in hypotension. BBB permeability, extravasation of plasma proteins into the brain parenchyma, activation of glial cells, and elevation of pro-inflammatory response mediators were detected. Furthermore, infiltrating innate immune cells were observed entering the brain through the lateral ventricle walls and the neurovascular unit. Mice showed normal locomotion function, yet cognition was impaired and depressive-like behavior was evident. In conclusion, our results highlight the important role of regulated plasma C1INH as it acts as a gatekeeper to the brain via the neurovascular system. Thus, manipulation of C1INH in neurovascular disorders might be therapeutically beneficial.

Effect of sildenafil citrate on the liver structure and function in obstructive jaundice: An experimental study

Objective

We aimed to investigate the effect of 10 mg/kg sildenafil on the structure and function of the liver in a rat model of obstructive jaundice.

Material and Methods

Sixty-two male Wistar albino rats were distributed into six different groups. Obstructive jaundice was performed by legating the common bile duct. 10 mg/kg sildenafil citrate in drinking water was delivered orally after the operation before sacrificing them. Rats were sacrificed either after 10 or 28 days according to the study design. The blood and tissue samples from the liver were obtained to perform a biochemical and histopathological analysis to study functional and structural changes in the liver.

Results

At the 10th day, there was no difference between the sildenafil-treated and control groups with regard to the aspartate aminotransferase and alanine aminotransferase levels (p=0.423, p=0.661). The alkaline phosphatase total bilirubin levels among the groups were statistically different (p<0.001). At the 28th day, liver function tests except alanine aminotransferase showed significant differences among the groups (p<0.001). Liver function tests did not changed significantly between the 10th and 28th day in sildenafil-treated rats (p>0.05). Significant differences were observed among the groups with regard to cholestasis, fibrosis, inflammation, and necrosis (p<0.001). However, edema increased in the sildenafil-treated group (p<0.001). On the 28th day, the severity of structural changes in the liver after obstructive jaundice, except edema, reduced significantly (p<0.001). The sildenafil-treated groups at different time points didn't show any statistical difference in histopathological changes (p>0.05).

Conclusion

Oral administration of 10 mg/kg sildenafil citrate dramatically reverses the biochemical and histopathological liver changes induced by obstructive jaundice in rats.

Effect of nebivolol on liver regeneration in an experimental 70% partial hepatectomy model

BACKGROUND

Factors affecting liver regeneration are still relevant. The purpose of this study is to investigate the effect of nebivolol treatment on liver regeneration in rats in which 70% partial hepatectomy was performed.

METHODS

Three groups were created: the control group, the low dose group, and the high dose group, with 20 rats in each group and 70% hepatectomy was performed in all rats. Immediately after partial liver resection, 2 mL physiological saline solution was administered to the control group via oral gavage, 0.5 mg/kg nebivolol was administered via oral gavage to the low dose group and 2 mg/kg nebivolol was administered via oral gavage to the high dose group. On the 1^st and 5^th days after liver resection, 10 subjects were sacrificed from each group, and liver weights and the mitotic count and Ki-67 were measured.

RESULTS

Regenerating liver weight on the 1^st and 5^th days after partial hepatectomy was statistically different in the low dose and high dose nebivolol groups compared to the control group. Mitotic count on the 1^st day after partial hepatectomy was significantly higher in the low dose and high dose nebivolol groups than the control group. There was no statistically significant difference detected between the three groups for the 5^th day. On the 1^st day, Ki-67 rates were significantly higher in both groups given nebivolol than the control group. However, 5^th day results were not statistically significant.

CONCLUSION

Nebivolol increases regeneration after partial hepatectomy in rats.

Markers of bacterial translocation in end-stage liver disease

Bacterial translocation (BT) refers to the passage of viable bacteria or bacterial products from the intestinal lumen, through the intestinal epithelium, into the systemic circulation and extraintestinal locations. The three principal mechanisms that are thought to be involved in BT include bacterial overgrowth, disruption of the gut mucosal barrier and an impaired host defence. BT is commonly observed in liver cirrhosis and has been shown to play an important role in the pathogenesis of the complications of end stage liver disease, including infections as well as hepatic encephalopathy and hepatorenal syndrome. Due to the importance of BT in the natural history of cirrhosis, there is intense interest for the discovery of biomarkers of BT. To date, several such candidates have been proposed, which include bacterial DNA, soluble CD14, lipopolysaccharides endotoxin, lipopolysaccharide-binding protein, calprotectin and procalcitonin. Studies on the association of these markers with BT have demonstrated not only promising data but, oftentimes, contradictory results. As a consequence, currently, there is no optimal marker that may be used in clinical practice as a surrogate for the presence of BT.

Targeting the gut-liver axis in cirrhosis: antibiotics and non-selective β-blockers

The gut-liver axis in cirrhosis and portal hypertension is gaining increasing attention as a key pathophysiological mechanism responsible for progression of liver failure and development of complications such as spontaneous infections and hepatocellular carcinoma. Antibiotics and non-selective β-blockers (NSBB) intercept this axis and each drug has proven efficacy in clinical trials. A synergistic effect is a hitherto unproven possibility. There is an increasing body of evidence supporting improved outcome with expanded use of NSBB and antibiotic therapy beyond current indications. This review addresses the issue of pharmacological treatment of cirrhosis and portal hypertension with antibiotics and NSBB. We discuss their mechanism of action and suggest that combining the two treatment modalities could potentially reduce the risk of complications.

Sildenafil accelerates liver regeneration after partial hepatectomy in rats

OBJECTIVE

The regeneration process causes the liver to achieve an adequate volume and function after major hepatectomy or living donor liver transplantation. Sildenafil, a selective phosphodiesterase-5 inhibitor used for erectile dysfunction, impacts the liver by enhancing the effects of nitric oxide. The aim of this study was to investigate the influence of sildenafil on liver regeneration in rats after partial hepatectomy.

METHODS

Sixty young female Wistar Albino rats were randomly divided into three equal groups before 70% hepatectomy. Thereafter, we administered intraperitoneal saline to the control group (G1); 10 μg/kg sildenafil to the low-dose group (G2) and 100 μg/kg to the high-dose sildenafil group (G3). Half of the rats per group were sacrificed on the first and the other half on the fifth postoperative day after partial hepatectomy. Regeneration was assessed using three methods: (1) the formula described by Kwon et al formula, (2) the average number of mitotic figures in 10 microscopic fields, and (3) the average of Ki-67-positive nuclei in 1000 cells using immunohistochemistry.

RESULTS

Although, the hepatic regeneration and mitosis rates were similar in all three groups, Ki-67 levels were significantly higher in both G2 and G3 than the control group on the first postoperative day. Hepatic regeneration was significantly greater in G2 and G3 than the control group as was the mitosis rate in the G2 group versus the two groups. By the 5th postoperative day Ki-67 levels were similar in the three groups.

CONCLUSION

Sildenafil treatment accelerated hepatic regeneration after partial hepatectomy in rats.

Pathological bacterial translocation in cirrhosis: pathophysiology, diagnosis and clinical implications

Bacterial translocation (BT) is defined by the passage of viable indigenous bacteria from the intestinal lumen to mesenteric lymph nodes (MLNs) and other territories, and its diagnostic criteria rely on the isolation of viable bacteria in MLNs. Small intestinal overgrowth, increased intestinal permeability and immunological alterations are the main factors involved in its pathogenesis. BT is obviously difficult to identify in patients with cirrhosis, and alternative methods have been proposed instead. Bacterial DNA detection and species identification in serum or ascitic fluid has been proposed as a reliable marker of BT. Bacterial products, such as endotoxin, or bacterial DNA can translocate to extra-intestinal sites and promote an immunological response similar to that produced by viable bacteria. Therefore, pathological BT plays an important role in the pathogenesis of the complications of cirrhosis, not only in infections, but by exerting a profound inflammatory state and exacerbating the haemodynamic derangement. This may promote in turn the development of hepatorenal syndrome, hepatic encephalopathy and other portal hypertension-related complications. Therapeutic approaches for the prevention of BT in experimental and human cirrhosis are summarized. Finally, new investigations are needed to better understand the pathogenesis and consequences of translocation by viable bacteria (able to grow in culture), or non-viable BT (detection of bacterial fragments with negative culture) and open new therapeutic avenues in patients with cirrhosis.

Nitric oxide and prostaglandin as mediators in the pathogenesis of hyperkinetic circulatory state in a model of endotoxemia-induced portal hypertension

AIMS

To evaluate the participation of nitric oxide (NO) and prostaglandin (PGI2) on hyperdynamic state in endotoxemia-induced portal hypertension (EIP) induced by chronic endotoxemia.

METHODS

The portal pressure (PP) and mean arterial pressure (MAP) were recorded, in vivo before and after administration of L-NAME (NOS inhibitor) and indomethacin (specific blocker of COX). The vasoactive responses to acetylcholine of thoracic rat aortic rings were studied in vitro before and after nitric oxide and cyclooxygenase blockade using multichannel organ bath. The mRNA expression for isoforms of (cyclooxygenase) COX and nitric oxide synthase (NOS) were analyzed using RT-PCR.

RESULTS

Administration of both L-NAME and indomethacin in EIP rabbits significantly reduced (p < 0.05) the PP and reversed the MAP to normal as compared to sham-operated (SO) rabbits. There was impaired vasodilatory response to acetylcholine in EIP rabbits. L-NAME caused a significant reduction in acetylcholine-induced vasorelaxation in SO rabbits than EIP due to preexisting hyperemia in EIP. Indomethacin partially restored vasoresponsiveness to acetylcholine in EIP group. The mRNA expression of eNOS (endothelial NOS) and COX-1 (constitutive COX) were significantly higher in SO than EIP rabbits. iNOS (inducible NOS) and COX-2 (inducible COX) mRNA expression was seen only in EIP rabbits.

CONCLUSIONS

A significant component of acetylcholine-mediated vasorelaxation in EIP model is modulated by eNOS. There was increased production of contractile prostaglandin in EIP rabbits. iNOS and COX-2 play an important role in the hemodynamic abnormalities of PHT. This novel model of PHT produced by chronic splanchnic endotoxemia in rabbit, mimics impaired vasodilation and vasoreactivity akin to other models of PHT.

Udenafil enhances the recovery of erectile function and ameliorates the pathophysiological consequences of cavernous nerve resection

INTRODUCTION

Radical prostatectomy is the treatment of choice for prostate cancer patients. Despite the introduction of nerve-sparing surgical techniques, its success is not entirely guaranteed and the majority of patients report compromised erectile function following surgical procedures.

AIM

This study was performed to investigate the effect of repeated dosing of udenafil, a novel phosphodiesterase type 5 inhibitor, on penile hypoxia and fibrosis induced by bilateral cavernous nerve resection (BCNR) in rats.

METHODS

Thirty male Sprague-Dawley rats (300-320 g) were used in this study. The animals were divided into three groups; group I consisted of sham-operated animals (N = 10), animals in group II underwent BCNR alone (N = 10), and animals in group III were orally treated with 10 mg/kg udenafil b.i.d. for 8 weeks following BCNR (N = 10).

MAIN OUTCOME MEASURES

The expression of transforming growth factor-beta1, hypoxia-inducible factor-1 alpha, endothelial nitric oxide synthase, neuronal nitric oxide synthase, and endothelin B receptor in penile tissue was examined at gene level. Additionally, erectile function, measured by intracavernous pressure (ICP), and pathological changes in the corpus cavernosum were examined.

RESULTS

While fibrosis, apoptosis, and the expression of TGF-beta1, HIF-1 alpha, and ET(B) were significantly increased, and the expression of eNOS and nNOS were significantly decreased in group II, compared with the sham-operated animals, repeated dosing of udenafil significantly ameliorated these changes. Erectile function was profoundly impaired in animals that underwent BCNR alone, and udenafil treatment significantly attenuated this impairment as measured by ICP.

CONCLUSIONS

These results demonstrate that long-term administration of udenafil ameliorates penile hypoxia and fibrosis induced by cavernous nerve resection. This study also suggests the potential beneficial role of repeated dosing of udenafil in the recovery of erectile function in patients with neuronal erectile dysfunction.

Innate immune dysfunction in acute and chronic liver disease

Liver cirrhosis is a common disease causing great public-health concern because of the frequent complications requiring hospital care. Acute liver failure is also prone to several complications but is rare. One of the main complications for both acute and chronic liver diseases is infection, which regularly causes decompensation of cirrhosis, possibly leading to organ failure and death. This review focuses on innate immune function in cirrhosis, acute-on-chronic liver failure and acute liver failure. The known defects of Kupffer cells, neutrophils and monocytes are discussed, together with the pathophysiological importance of gut permeability, portal hypertension and intrinsic cellular defects, and the role of endotoxin, albumin, lipoproteins and toll-like receptors. Based on these different pathomechanisms, the available information on therapeutic strategies is presented. Antibiotic and probiotic treatment, nutritional support, artificial liver support, and experimental strategies such as inhibition of toll-like receptors and use of albumin and colony-stimulating factors are highlighted.

Intestinal decontamination improves liver haemodynamics in patients with alcohol-related decompensated cirrhosis

BACKGROUND

Endotoxaemia is commonly seen in cirrhotic patients with ascites and this may be associated with increased portal pressure.

AIM

To investigate the effect of intestinal decontamination on liver haemodynamics in alcohol-related cirrhotic patients with ascites.

METHODS

We included 30 patients. At day 0, systemic and splanchnic circulation endotoxin levels were determined and HVPG measurement performed. Patients received rifaximin (1200 mg/day) for 28 days. At day 29, systemic and splanchnic circulation endotoxin levels were determined and HVPG measurement performed again.

RESULTS

Median (range) plasma endotoxin levels decreased significantly after rifaximin administration both in systemic [1.45(0-3.1) vs. 0.7(0-2.7), P < 0.0001] and splanchnic circulation [1.8(0-3.4) vs. 0.8(0-2.1), P < 0.0001]. Meanwhile, the difference seen in endotoxin levels between the splanchnic and systemic circulation at day 0 (P = 0.001) was not noted at day 29 (P = 0.137). HVPG measurement was possible in 28 patients. Median (range) HVPG values were 18 mmHg (12.7-26.3) on day 0 vs. 14.7 mmHg (7-20) on day 29 (P < 0.0001). HVPG decreased after rifaximin in 23, remained stable in two and increased in three patients.

CONCLUSION

Hepatic venous pressure gradient values decreased significantly after intestinal decontamination with rifaximin in patients with alcohol-related decompensated cirrhosis and this might have been achieved through significant reduction of plasma endotoxin levels.

Effect of pyrrolidine dithiocarbamate on hepatic vascular stress gene expression during ischemia and reperfusion

Pyrrolidine dithiocarbamate, an antioxidant and a potent inhibitor of nuclear factor-kappa B (NF-kappaB), is known to have protective effect against ischemia and reperfusion injury. This study examined the cytoprotective mechanism of pyrrolidine dithiocarbamate against the microcirculatory failure caused by hepatic ischemia and reperfusion. Rats were subjected to 60 min of hepatic ischemia followed by 5 h of reperfusion. Pyrrolidine dithiocarbamate (100 mg/kg) or the vehicle was administered intraperitoneally 24 h before ischemia. The level of serum aminotransferases and hepatic lipid peroxides significantly increased, and the glutathione contents fell in the ischemia/reperfusion group. Pyrrolidine dithiocarbamate prevented the increase in the level of serum enzymes and hepatic lipid peroxides, and the decrease in the glutathione contents. The NF-kappaB DNA-binding activity was inhibited by a pre-treatment with pyrrolidine dithiocarbamate. Ischemia and reperfusion significantly increased the mRNA expression of the endothelin-1 and endothelin ET(B) receptor, which was prevented by pyrrolidine dithiocarbamate. There were significant increases in the mRNA expressions of inducible nitric oxide synthase, tumor necrosis factor-alpha, and cyclooxygenase-2, in the livers after ischemia and reperfusion. These increases were attenuated by the pyrrolidine dithiocarbamate treatment. In a rat model of hepatic ischemia and reperfusion, our results suggest that the hepatoprotective actions of pyrrolidine dithiocarbamate may be mediated in part through the modulation of imbalanced expression of vascular stress genes.

LPS exacerbates endothelin-1 induced activation of cytosolic phospholipase A2 and thromboxane A2 production from Kupffer cells of the prefibrotic rat liver

BACKGROUND/AIMS

Thromboxane A2 (TXA2) has been suggested to play a significant role in the development of portal hypertension in fibrosis, and Kupffer cell (KC) derived TXA2 has been shown to mediate the hyperresponsiveness of the portal circulation to the vasoconstrictive actions of endothelin-1 (ET-1) during endotoxemia. The aim of this study was to determine whether the double stresses of prefibrotic changes and endotoxemia additively activate KC to increase release of TXA2 in response to ET-1, resulting in elevated portal resistance.

METHODS

One week Bile duct ligation (BDL) rats and sham-operated controls were subjected to isolated liver perfusions following LPS or saline for 6h. In a separate experiment, KC were isolated from BDL or sham rats and incubated with LPS or saline for 6h before the ET-1 treatment.

RESULTS

The double stresses of early fibrosis and LPS resulted in a greater sustained increase in portal pressure in response to ET-1 in BDL rats, and this increase correlated well with the much enhanced release of TXA2 in the perfusate. Media from the cultured KC showed significantly greater TXA2 release in response to ET-1 in BDL group than those in sham group, and LPS exacerbated this effect. Protein levels of cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2, and thromboxane synthase were also significantly elevated in KC from BDL rats. ET-1 produced a marked increase in cPLA2 activation as measured by the phosphorylation of cPLA2 in KC of both BDL and sham groups. LPS greatly exacerbated the activation of cPLA2.

CONCLUSIONS

The data suggest that the double stresses additively activate KC with an upregulation of the key enzymes in the TXA2 biosynthesis and release increased amount of TXA2 via the augmented activation of cPLA2 in response to ET-1, which leads to the increased portal resistance and ultimately hepatic microcirculatory dysfunction.

Infection et rupture de varice œsophagienne au cours de la cirrhose

Endotoxemia and bacterial infection are frequent in patients with cirrhosis. They alter systemic and splanchnic hemodynamics, worsen coagulation disorders, impair liver function and thus may induce variceal bleeding. In variceal bleeding, bacterial infection favours failure to control bleeding, early rebleeding, and death. In patients with cirrhosis and variceal bleeding, antibiotic-prophylaxis decreases bacterial infection and the incidence of early rebleeding, and, more important, significantly decreases the death rate in these patients.

Inhibition of endothelin-1-mediated up-regulation of iNOS by bosentan ameliorates endotoxin-induced liver injury in cirrhosis

Endothelin-1 (ET-1) has been shown to regulate the expression of various genes in addition to its vasoconstrictor role in the liver. Elevated levels of ET-1 during cirrhosis play an important role in the observed microcirculatory dysfunction; however, its role as a transcription regulator remains unclear. This study aimed to determine the role of ET-1 in the hepatic gene expression of vasomediators after cirrhosis in response to LPS. Cirrhosis was induced by bile duct ligation (BDL) for 1 or 3 weeks in male Sprague-Dawley rats. Following 1 or 3 weeks of BDL or sham operation (sham), rats received an intravenous (i.v.) injection of bosentan, a dual-selective ETA/B receptor antagonist (30 mg/kg bw) or saline, and an intraperitoneal (i.p.) injection of LPS (1 mg/kg bw). Plasma alanine aminotransferase (ALT) levels were significantly elevated in 1- and 3-week BDL animals. Six hours following LPS, the elevated ALT levels were markedly exacerbated in 3-week BDL animals, which were significantly ameliorated with bosentan treatment. LPS resulted in increased ET-1, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2 mRNA expressions in both sham and BDL rats. Bosentan significantly inhibited the up-regulations of ET-1, iNOS, and COX-2 mRNA. Our data strongly suggest that ET-1 plays an important role in up-regulating the expression of iNOS, COX-2, and ET-1 itself in hepatic tissue following LPS challenge, which may contribute to the observed hepatocellular injury during endotoxemia in cirrhosis. Thus, due to significant increases in ET-1 levels during cirrhosis, ET-1 receptor blockade may prove to be of great therapeutic value in the treatment of cirrhotic patients exposed to secondary injuries such as endotoxemia.

LPS inhibits endothelin-1-induced endothelial NOS activation in hepatic sinusoidal cells through a negative feedback involving caveolin-1

During endotoxemia, liver microcirculation disruption is characterized by a hypersensitivity to the constrictor effects of endothelin 1 (ET-1). The shift of ET-1-mediated effects toward vasoconstriction may result from depressed ET-1-mediated vasodilation through decreased ET-1-induced nitric oxide (NO) production. We have previously shown that lipopolysaccharide (LPS) pretreatment abrogates ET-1-induced endothelial nitric oxide synthase (eNOS) translocation, but its effects on eNOS activation are yet to be determined. Our aim was to assess the effects of LPS on ET-1-mediated eNOS activation in hepatic sinusoidal endothelial cells (SECs) and to investigate the molecular mechanisms involved. SECs were treated with LPS (100 ng/mL) for 6 hours followed by 30 minutes ET-1 (10 nmol/L) stimulation. LPS significantly inhibited ET-1-mediated eNOS activation. This inhibition was associated with upregulation of Caveolin-1 (CAV-1) and a shift in ET-1-mediated eNOS phosphorylation from an activation (Ser1177) to an inhibition (Thr495). LPS treatment has been shown to induce ET-1 expression and secretion from endothelial cells. We therefore investigated the role of endogenous ET-1 in the inhibition of ET-1 activation of eNOS after LPS. Antagonizing ET-1 effects and blocking its activation in LPS pretreated SECs decreased the LPS-induced overexpression of CAV-1 as well as the inhibition of ET-1-induced NOS activity. Furthermore, 6 hours of ET-1 treatment exerted the same effects on eNOS activity, phosphorylation, and CAV-1 expression as LPS treatment. In conclusion, LPS-induced suppression of ET-1-mediated eNOS activation is ET-1 dependent and suggest a pivotal role of CAV-1 in eNOS induction inhibition under stress.

Influence of inhalation anesthesia assessed by comprehensive gene expression profiling

Although general anesthesia is routinely used as an essential surgical procedure and its harmlessness has been evaluated and endorsed by clinical outcomes, little is known about its comprehensive influence that is not reflected in mortality and morbidity. In this paper, we have shown that inhalation anesthesia affected the expression of <1.5% of >10,000 genes, by analyzing the expression profiles for multiple organs of rats anesthetized with sevoflurane. The small number of transcripts affected by the inhalation anesthesia comprised those specific to single and common in multiple organs. The former included genes mainly associated with drug metabolism in the liver and influenced by agents such as amphetamine in the brain. The latter contained multiple circadian genes. In the brain, we failed to detect the alteration of the clock gene expression with the exception of Per2, assuming that anesthesia perturbs circadian rhythms. Our findings provide the first assessment for the influence of inhalation anesthesia by approaches of experimental biology and genome science.

Effects of sildenafil citrate on hepatic function and regeneration in normal and alcohol-fed rats

Sildenafil citrate is a potent inhibitor of specific phosphodiesterase-5, which mediates metabolism of intracellular second message -- cGMP. Sildenafil citrate has been widely used for erectile dysfunction in men. Moreover, it is known that men with liver diseases have higher rate of erectile dysfunction. Furthermore, it has been demonstrated that nitric oxide plays an important role in liver function and regeneration. The present study evaluates effects of sildenafil citrate on hepatic function and regeneration in normal and alcohol-fed rats. In normal rats sildenafil citrate has a trend to improve hepatic function after partial hepatectomy (PHx). Moreover, sildenafil citrate significantly reduces hepatic regenerative activity at the concentration of 5 mg/kg body weight. However, sildenafil had no effects on hepatic function and regeneration of alcohol-fed rats. In general, sildenafil citrate did not induce significant changes in hepatic function and regenerative activity after PHx in normal and alcohol-fed rats, except at concentration of 5 mg/kg sildenafil citrate significantly inhibit hepatic regeneration in normal rats.

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.