Rifaximin Prevents Intestinal Barrier Dysfunction and Alleviates Liver Injury in MCT-induced HSOS Mice

OBJECTIVE

Rifaximin is an effective component of treatment strategies for liver and intestinal diseases. However, the efficacy of rifaximin in hepatic sinusoidal obstruction syndrome (HSOS) has not been explored. The present study aimed to investigate the efficacy and mechanism of rifaximin in HSOS.

METHODS

An HSOS model was established in mice through the administration of monocrotaline (MCT, 800 mg/kg), and part of the HSOS mice were intragastrically administered with rifaximin. Then, the efficacy of rifaximin in HSOS was evaluated based on the liver pathological findings, liver proinflammatory cytokines, and alanine aminotransferase and aspartate aminotransferase levels. The Ussing chamber was used to evaluate the intestinal permeability, and tight junction (TJ) proteins were measured by Western blotting and real-time polymerase chain reaction to evaluate the intestinal barrier integrity. Then, the serum proinflammatory cytokine levels were evaluated by enzyme-linked immunosorbent assay. Afterwards, an in vitro experiment was performed to determine the relationship between rifaximin and TJ proteins.

RESULTS

Rifaximin effectively alleviated the MCT-induced HSOS liver injury, suppressed the expression of liver proinflammatory cytokines, and reduced the serum levels of tumor necrosis factor-alpha and interleukin-6. Furthermore, rifaximin reduced the intestinal permeability, improved the intestinal barrier integrity, and promoted the expression of TJ proteins.

CONCLUSION

The results revealed that the intestinal barrier integrity was destroyed in MCT-induced HSOS. The significant alleviation of MCT-induced HSOS induced by rifaximin might be correlated to the repairment of intestinal barrier integrity via the regulation of the TJ protein expression.

Andrographolide attenuated MCT-induced HSOS via regulating NRF2-initiated mitochondrial biogenesis and antioxidant response

Hepatic sinusoidal obstruction syndrome (HSOS) is a death-dealing liver disease with a fatality rate of up to 67%. In the study present, we explored the efficacy of andrographolide (Andro), a diterpene lactone from Andrographis Herba, in ameliorating the monocrotaline (MCT)-induced HSOS and the underlying mechanism. The alleviation of Andro on MCT-induced rats HSOS was proved by biochemical index detection, electron microscope observation, and liver histological evaluation. Detection of hepatic ATP content, mitochondrial DNA (mtDNA) copy number, and protein expression of nuclear respiratory factor-1 (NRF1) and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) demonstrated that Andro strengthened mitochondrial biogenesis in livers from MCT-treated rats. Chromatin immunoprecipitation assay exhibited that Andro enhanced the occupation of nuclear factor erythroid 2-related factor 2 (NFE2L2, also known as NRF2) in the promoter regions of both PPARGC1A and NRF1. Andro also activated the NRF2-dependent anti-oxidative response and alleviated liver oxidative injury. In Nrf2 knock-out mice, MCT induced more severe liver damage, and Andro showed no alleviation in it. Furthermore, the Andro-activated mitochondrial biogenesis and anti-oxidative response were reduced in Nrf2 knock-out mice. Contrastingly, knocking out Kelch-like ECH-associated protein 1 (Keap1), a NRF2 repressor, reduced MCT-induced liver damage. Results from co-immunoprecipitation, molecular docking analysis, biotin-Andro pull-down, cellular thermal shift assay, and surface plasmon resonance assay showed that Andro hindered the NRF2-KEAP1 interaction via directly binding to KEAP1. In conclusion, our results revealed that NRF2-dependent liver mitochondrial biogenesis and anti-oxidative response were essential for the Andro-provided alleviation of the MCT-induced HSOS. Graphical Headlights: 1. Andro alleviated MCT-induced HSOS via activating antioxidative response and promoting mitochondrial biogenesis. 2. Andro-activated antioxidative response and mitochondrial biogenesis were NRF2-dependent. 3. Andro activated NRF2 via binding to KEAP1.

A TMT-based shotgun proteomics uncovers overexpression of thrombospondin 1 as a contributor in pyrrolizidine alkaloid-induced hepatic sinusoidal obstruction syndrome

Hepatic sinusoidal obstruction disease (HSOS) is a rare but life-threatening vascular liver disease. However, its underlying mechanism and molecular changes in HSOS are largely unknown, thus greatly hindering the development of its effective treatment. Hepatic sinusoidal endothelial cells (HSECs) are the primary and essential target for HSOS. A tandem mass tag-based shotgun proteomics study was performed using primary cultured HSECs from mice with HSOS induced by senecionine, a representative toxic pyrrolizidine alkaloid (PA). Dynamic changes in proteome were found at the initial period of damage and the essential role of thrombospondin 1 (TSP1) was highlighted in PA-induced HSOS. TSP1 over-expression was further confirmed in human HSECs and liver samples from patients with PA-induced HSOS. LSKL peptide, a known TSP1 inhibitor, protected mice from senecionine-induced HSOS. In addition, TSP1 was found to be covalently modified by dehydropyrrolizidine alkaloids in human HSECs and mouse livers upon senecionine treatment, thus to form the pyrrole-protein adduct. These findings provide useful information on early changes in HSECs upon PA treatment and uncover TSP1 overexpression as a contributor in PA-induced HSOS.

NRF2 activates growth factor genes and downstream AKT signaling to induce mouse and human hepatomegaly

BACKGROUND & AIMS

Hepatomegaly can be triggered by insulin and insulin-unrelated etiologies. Insulin acts via AKT, but how other challenges cause hepatomegaly is unknown.

METHODS

Since many hepatomegaly-inducing toxicants and stressors activate NRF2, we examined the effect of NRF2 activation on liver size and metabolism using a conditional allele encoding a constitutively active NRF2 variant to generate Nrf2Act-hep mice in which NRF2 is selectively activated in hepatocytes. We also used adenoviruses encoding variants of the autophagy adaptor p62/SQSTM1, which activates liver NRF2, as well as liver-specific ATG7-deficient mice (Atg7Δhep) and liver specimens from patients with hepatic sinusoidal obstruction syndrome (HSOS) and autoimmune hepatitis (AIH). RNA sequencing and cell signaling analyses were used to determine cellular consequences of NRF2 activation and diverse histological analyses were used to study effects of the different manipulations on liver and systemic pathophysiology.

RESULTS

Hepatocyte-specific NRF2 activation, due to p62 accumulation or inhibition of KEAP1 binding, led to hepatomegaly associated with enhanced glycogenosis, steatosis and G2/M cell cycle arrest, fostering hyperplasia without cell division. Surprisingly, all manipulations that led to NRF2 activation also activated AKT, whose inhibition blocked NRF2-induced hepatomegaly and glycogenosis, but not NRF2-dependent antioxidant gene induction. AKT activation was linked to NRF2-mediated transcriptional induction of PDGF and EGF receptor ligands that signaled through their cognate receptors in an autocrine manner. Insulin and insulin-like growth factors were not involved. The NRF2-AKT signaling axis was also activated in human HSOS- and AIH-related hepatomegaly.

CONCLUSIONS

NRF2, a transcription factor readily activated by xenobiotics, oxidative stress and autophagy disruptors, may be a common mediator of hepatomegaly; its effects on hepatic metabolism can be reversed by AKT/tyrosine kinase inhibitors.

LAY SUMMARY

Hepatomegaly can be triggered by numerous etiological factors, including infections, liver cancer, metabolic disturbances, toxicant exposure, as well as alcohol abuse or drug-induced hepatitis. This study identified the oxidative stress response transcription factor NRF2 as a common mediator of hepatomegaly. NRF2 activation results in elevated expression of several growth factors. These growth factors are made by hepatocytes and activate their receptors in an autocrine fashion to stimulate the accumulation of glycogen and lipids that lead to hepatocyte and liver enlargement. The protein kinase AKT plays a key role in this process and its inhibition leads to reversal of hepatomegaly.

Chlorogenic acid suppresses monocrotaline-induced sinusoidal obstruction syndrome: The potential contribution of NFκB, Egr1, Nrf2, MAPKs and PI3K signals

Hepatic sinusoidal obstruction syndrome (SOS) is a highly lethal liver disease. This study aims to observe the protection and its engaged mechanism of chlorogenic acid (CGA) against monocrotaline (MCT)-induced SOS. Results of detecting liver ascites, measuring serum transaminases, liver histological evaluation and scanning electron microscope observation all demonstrated that CGA prevented MCT-induced SOS in rats. CGA reduced MCT-induced increased liver myeloperoxidase (MPO) activity, tumor necrosis factor (TNF)α and interleukin (IL)-1β mRNA expression, toll-like receptor (TLR)-2,3,6,9 expression, and nuclear factor κB (NFκB) transcriptional activation. CGA also decreased MCT-induced early growth response1 (Egr1) activation. CGA reduced MCT-induced elevated liver malondialdehyde (MDA) amount and enhanced nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). CGA blocked MCT-induced PI3K and MAPKs activation. In conclusion, this study demonstrates the protection of CGA against MCT-induced SOS. Transcriptional factor NFκB, Egr1 and Nrf2-regulated inflammation, coagulation-fibrinolysis, and antioxidant, and PI3K and MAPKs all contribute to such protection.

Sorafenib attenuates monocrotaline-induced sinusoidal obstruction syndrome in rats through suppression of JNK and MMP-9

BACKGROUND & AIMS

Sinusoidal obstruction syndrome (SOS) is a drug-induced liver injury that occurs with oxaliplatin treatment and is associated with postoperative morbidity after hepatectomy. The aim of this study was to investigate the effects of sorafenib in a monocrotaline (MCT)-induced model of SOS in rats.

METHODS

Rats were divided into groups treated with sorafenib (2mg/kg) or vehicle, 36 h and 12h before MCT (90 mg/kg) administration by gavage. Liver tissues and blood were sampled 48 h after MCT administration to evaluate SOS. Survival after hepatectomy was examined and immunohistochemistry and electron microscopy were performed to assess sinusoidal injury.

RESULTS

In the vehicle group, liver histology showed sinusoidal dilatation, coagulative necrosis of hepatocytes, endothelial damage of the central vein, and sinusoidal hemorrhage. In the sorafenib group, these changes were significantly suppressed, total SOS scores were significantly decreased, and the elevation of serum transaminase levels observed in the vehicle group was significantly reduced. Survival after hepatectomy was significantly higher in the sorafenib group compared to the vehicle group (45% vs. 20%, p=0.0137). Immunohistochemistry and electron microscopy revealed a protective effect of sorafenib on sinusoidal endothelial cells at 6h after MCT treatment. Sorafenib also attenuated the activity of metallopeptidase-9 (MMP-9) and phosphorylation of c-Jun N-terminal kinase (JNK).

CONCLUSIONS

Sorafenib reduced the severity of MCT-induced SOS in rats through suppression of MMP-9 and JNK activity, resulting in improvement of survival after hepatectomy.

Defibrotide for the treatment of severe hepatic veno-occlusive disease and multiorgan failure after stem cell transplantation: a multicenter, randomized, dose-finding trial

Therapeutic options for severe hepatic veno-occlusive disease (VOD) are limited and outcomes are dismal, but early phase I/II studies have suggested promising activity and acceptable toxicity using the novel polydisperse oligonucleotide defibrotide. This randomized phase II dose-finding trial determined the efficacy of defibrotide in patients with severe VOD following hematopoietic stem cell transplantation (HSCT) and identified an appropriate dose for future trials. Adult and pediatric patients received either lower-dose (arm A: 25 mg/kg/day; n = 75) or higher-dose (arm B: 40 mg/kg/day; n = 74) i.v. defibrotide administered in divided doses every 6 hours for > or =14 days or until complete response, VOD progression, or any unacceptable toxicity occurred. Overall complete response and day +100 post-HSCT survival rates were 46% and 42%, respectively, with no significant difference between treatment arms. The incidence of treatment-related adverse events was low (8% overall; 7% in arm A, 10% in arm B); there was no significant difference in the overall rate of adverse events between treatment arms. Early stabilization or decreased bilirubin was associated with better response and day +100 survival, and decreased plasminogen activator inhibitor type 1 (PAI-1) during treatment was associated with better outcome; changes were similar in both treatment arms. Defibrotide 25 or 40 mg/kg/day also appears effective in treating severe VOD following HSCT. In the absence of any differences in activity, toxicity or changes in PAI-1 level, defibrotide 25 mg/kg/day was selected for ongoing phase III trials in VOD.

Mechanisms and pathophysiological implications of sinusoidal endothelial cell gap formation following treatment with galactosamine/endotoxin in mice

Neutrophil extravasation from sinusoids is a critical step for acute inflammatory tissue injury. However, the role of sinusoidal endothelial cells (SECs) in this process remains unclear. Matrix metalloproteinases (MMPs) have been shown to involve gap formation in SECs in several liver diseases. Therefore, the present study examined SEC modifications elicited by galactosamine (Gal)/endotoxin (ET). Treatment of male C3Heb/FeJ mice with Gal/ET or Gal/TNF caused the formation of numerous gaps in SECs at 4 h when no neutrophil extravasation occurred. Six hours after Gal/ET or Gal/TNF treatment, blood elements started to penetrate to the extrasinusoidal space through large gaps. Treatment with ET alone caused sinusoidal neutrophil accumulation but no gap formation, neutrophil extravasation, or hemorrhage. Gal/ET treatment increased hepatic MMP-2 and MMP-9 mRNA expression (6.7- and 11-fold, respectively). Pretreatment with 2-[(4-biphenylsulfonyl) amino]-3-phenyl-propionic acid, an MMP-2/MMP-9 inhibitor (5 mg/kg), minimized gap formation after Gal/ET and Gal/TNF treatment. The MMP inhibitor reduced injury only in the Gal/ET model mainly due to reduced TNF formation. The MMP inhibitor attenuated sinusoidal neutrophil accumulation at 6 h but failed to attenuate Gal/TNF-induced liver injury at 7 h due to excessive apoptosis. These results suggest that Gal/ET or Gal/TNF activates MMPs, which are responsible for SEC gap formation. Although the initial appearance of gap formation is independent of neutrophils, the gaps allow initial contact of neutrophils with damaged hepatocytes. In addition, MMP activation promotes neutrophil accumulation in sinusoids.

The hemochromatosis C282Y allele: a risk factor for hepatic veno-occlusive disease after hematopoietic stem cell transplantation

Hepatic veno-occlusive disease (HVOD) is a serious complication of hematopoietic stem cell transplantation (HSCT). Since the liver is a major site of iron deposition in HFE-associated hemochromatosis, and iron has oxidative toxicity, we hypothesized that HFE genotype might influence the risk of HVOD after myeloablative HSCT. We determined HFE genotypes in 166 HSCT recipients who were evaluated prospectively for HVOD. We also tested whether a common variant of the rate-limiting urea cycle enzyme, carbamyl-phosphate synthetase (CPS), previously observed to protect against HVOD in this cohort, modified the effect of HFE genotype. Risk of HVOD was significantly higher in carriers of at least one C282Y allele (RR=3.7, 95% CI 1.2-12.1) and increased progressively with C282Y allelic dose (RR=1.7, 95% CI 0.4-6.8 in heterozygotes; RR=8.6, 95% CI 1.5-48.5 in homozygotes). The CPS A allele, which encodes a more efficient urea cycle enzyme, reduced the risk of HVOD associated with HFE C282Y. We conclude that HFE C282Y is a risk factor for HVOD and that CPS polymorphisms may counteract its adverse effects. Knowledge of these genotypes and monitoring of iron stores may facilitate risk-stratification and testing of strategies to prevent HVOD, such as iron chelation and pharmacologic support of the urea cycle.

Pharmacokinetics of omeprazole in patients with liver cirrhosis and extrahepatic portal venous obstruction

Omeprazole is frequently used in patients with cirrhosis of the liver to treat peptic ulcer disease. It is also used for the healing of mucosal lesions after endoscopic sclerotherapy of esophageal varices in cirrhosis and extraheptic portal vein obstruction (EHPVO). This study was carried out with the aim of determining the pharmacokinetics of omeprazole in different degrees of liver cirrhosis and in patients with EHPVO, compared with healthy volunteers. Ten healthy volunteers, 30 patients with cirrhosis of the liver, divided into 3 groups of 10 depending on severity (according to Child-Pugh classification A, B and C) and ten patients with EHPVO participated in the study. The subjects received an omeprazole 20 mg capsule after an overnight fast. Blood samples were collected at 0, 0.5, 1, 1.5, 2, 2.5, 3, 6, 9 and 24 h after drug administration. Omeprazole level in plasma was estimated by reverse-phase high performance liquid chromatography (HPLC). The elimination half-life was significantly (p < 0.05) increased to 2.38 +/- 0.16, 3.26 +/- 0,12, 3.58 +/- 0.31 and 2.59 +/- 0.22 h in patients with different grades of cirrhosis (A, B and C) and also in patients with EHPVO, respectively, compared with 1.054 + 0.10 h in healthy volunteers. A similar significant increase (p < 0.05) was observed in the AUC(0alpha), while C(max) was significantly increased to 400.40 +/- 27.89 and 602 +/- 55.13 ng/ml in only grade C cirrhosis patients and EHPVO patients, compared with 303.5 +/- 36.42 ng/ml in healthy volunteers. No significant difference was observed in T(max). It was concluded that the metabolism of omeprazole was significantly impaired in both liver cirrhosis and EHPVO in comparison with healthy volunteers.

N-acetylcysteine for hepatic veno-occlusive disease after allogeneic stem cell transplantation

Three patients developed veno-occlusive disease of the liver (VOD) after allogeneic stem cell transplantation. On the day after diagnosis, N-acetylcysteine (NAC) was given, initially in loading doses and thereafter 50-150 mg/kg/day for 12 to 31 days. The maximum bilirubin levels were 137, 58 and 138 mmol/l in the three patients, respectively. After the introduction of NAC, bilirubin, aspartate aminotransferase, sIL-2 receptor and IL-8 decreased. All three patients achieved normal bilirubin levels and prothrombin times. To conclude, NAC may be useful for treatment of VOD.

Glutathione defense in non-parenchymal cells

Toxicity to nonparenchymal cells can result in disruption of the hepatic microcirculation, altered production of cytokines, and hepatic fibrosis. Many of the relevant insults produce oxidative stress or toxic metabolites that require glutathione detoxification. This article reviews the role of sinusoidal endothelial cell glutathione (GSH) in reperfusion injury, cytomegalovirus infection, and hepatic venoocclusive disease. The effects of oxidative stress and antioxidants on Kupffer cell production of cytokines and, in particular the potential benefit of antioxidants in the setting of reperfusion injury, are discussed. Oxidative stress upregulates collagen gene expression by stellate cells, and this is modulated by antioxidants. Current thinking on intrahepatic GSH and cysteine homeostasis is discussed. Finally, I review the published data on nonparenchymal GSH levels, glutathione S-transferase activity and isoenzyme pattern, and glutathione peroxidase activity.

Hepatic stellate cells (Ito cells) in veno-occlusive disease of the liver after allogeneic bone marrow transplantation

AIMS

To evaluate the role of activated hepatic stellate cells (HSCs) in hepatic veno-occlusive disease (VOD) after bone marrow transcription (BMT), we studied the distribution and area of activated HSCs by immunohistochemistry for alpha-smooth muscle actin (SMA).

METHODS AND RESULTS

We examined the liver of seven autopsy cases with hepatic VOD or without VOD after allogeneic BMT and five autopsy cases without liver disease as a control both microscopically and immunohistochemically. In normal liver tissues, SMA-positive cells were observed around the central veins, while they were more frequently noted along the sinusoidal walls as well as around the central veins in liver tissues with or without VOD after BMT. The area of activated HSCs increased significantly in zones 1 and 2, and more prominently in zone 3 of the liver tissues after BMT than normal liver tissues, and was much larger in zone 3 of liver tissues with VOD. The activated HSCs were immunohistochemically negative for the regulatory contractile proteins (heavy caldesmon and calponin).

CONCLUSIONS

These results indicated that the activated HSCs may play an important role in sinusoidal fibrosis and luminal narrowing or occlusion of the central veins in VOD after BMT.

Serum hyaluronic acid level reflects volume and ATP levels of the liver after extended hepatectomy with and without preoperative portal vein occlusion

The purpose of this study was to examine the hypothesis that the serum hyaluronic acid (HA) level reflects the volume and adenosine triphosphate (ATP) levels of the liver after extended hepatectomy (ExHx) with and without preoperative portal vein occlusion (PVO). Rats were randomly divided into two groups, PVO-ExHx and sham-ExHx. At the first stage, they underwent PVO or sham surgery by an occlusion of the portal vein supplying the left lateral and median lobes or by similar manipulation but without PVO, respectively. Seven days after first-stage surgery, both groups received ExHx exceeding portal vein-occluded lobes, which was the excision of the left lateral, median, and right lateral lobes of the liver reported as a 90% hepatectomy model. On Days 0, 1, 2, and 3 after ExHx, the serum HA concentrations, liver weights, and hepatic ATP levels were determined. Liver volumes were restored to similar levels in both groups, but restoration was faster in the PVO-ExHx group because preoperative PVO allowed the excised liver less volume. Lower serum HA levels were significantly associated with significantly higher hepatic ATP levels and with a lower mortality rate in the PVO-ExHx group. The serum HA level correlated significantly (P < 0.001) with the liver weight and hepatic ATP level. The serum HA level serves as a proxy for clinically important parameters following major hepatic surgery.

Cellular target of cyclophosphamide toxicity in the murine liver: role of glutathione and site of metabolic activation

Hepatic venoocclusive disease (HVOD) is caused by the disruption of the microcirculation by an as-yet unknown mechanism. Previous in vitro studies with azathioprine, monocrotaline, and dacarbazine suggested that toxins that cause HVOD initially causing HVOD target sinusoidal endothelial cells (SEC) perhaps via profound glutathione (GSH) depletion. The current study examines cyclophosphamide toxicity in SEC and hepatocytes, as well as the interplay between the two cell types. Cyclophosphamide was not directly toxic to SEC, but in coculture of SEC and hepatocytes, cyclophosphamide was significantly more toxic to SEC. Two cyclophosphamide metabolites, 4-hydroperoxycyclophosphamide and acrolein, were equally toxic to SEC, and toxicity occurred at 20-fold-lower concentrations than in hepatocytes. 4-Hydroperoxycyclophosphamide depleted GSH by greater than 95% before inducing cell death in SEC. When hepatocyte-GSH levels were sustained with supplemental methionine and serine in coculture, toxicity in both cell types was diminished. In coculture, SEC are significantly more susceptible than hepatocytes to cyclophosphamide toxicity, and this is likely caused by acrolein generated by the hepatocyte. As seen with other toxins implicated in HVOD, the profound depletion of SEC GSH precedes the onset of toxicity. The degree of cyclophosphamide toxicity induced in SEC is determined by both metabolic activation and GSH detoxification in the hepatocytes.

Toxicity of azathioprine and monocrotaline in murine sinusoidal endothelial cells and hepatocytes: the role of glutathione and relevance to hepatic venoocclusive disease

The mechanisms leading to hepatic venoocclusive disease (HVOD) remain largely unknown. Azathioprine and monocrotaline were studied as part of a series of studies looking at a variety of toxins that induce HVOD to find common features that might be of pathogenic significance. In a previous study, dacarbazine showed selective in vitro toxicity to sinusoidal endothelial cells (SEC) compared with hepatocytes and a key role for SEC glutathione (GSH) was demonstrated. Murine SEC and hepatocytes were isolated and studied in culture. Azathioprine and monocrotaline were found to be selectively more toxic to SEC than to hepatocytes. The relative resistance of hepatocytes to azathioprine was due to enhanced GSH defense: hepatocytes exposed to azathioprine maintained intracellular GSH levels better than SEC, particularly when supplemental GSH precursors were added, and hepatocyte resistance was completely overcome by depletion of intracellular GSH. In contrast, monocrotaline toxicity in hepatocytes was largely unaffected by depletion of GSH, which suggests that selectivity of monocrotaline for SEC may be attributable to differences in metabolic activation. Both compounds are detoxified by GSH in SEC, as demonstrated by enhanced toxicity in the presence of buthionine sulfoximine (BSO) and attenuation of toxicity with exogenous GSH. SEC GSH levels were more than 70% to 80% depleted by monocrotaline and azathioprine, respectively, before cell death. Azathioprine and monocrotaline are selectively toxic to SEC; the mechanism of toxicity in the SEC may be caused by profound GSH depletion.

The safety of total hepatic vascular occlusion in rabbits with acute extrahepatic cholestasis

The technique of normothermic total hepatic vascular occlusion (THVO) is achieved by concomitant clamping of the inferior vena cava above and below the liver in addition to portal inflow occlusion. In this study we investigated the use of THVO for 45 min in a rabbit model with acute cholestasis of 10 days' duration. In rabbits with normal preoperative liver functions (control group), serum total bilirubin, glutamic-pyruvic transaminase (SGPT), glutamic-oxaloacetic transaminase (SGOT), alkaline phosphate, and gamma-glutamyltranspeptidase levels returned to normal ranges within a week after THVO. In the group with persistent cholestasis THVO was performed 10 days after ligation of the extrahepatic bile duct. Total bilirubin and canalicular enzymes remained high while the SGOT and SGPT peaked and almost returned to the preoperative levels at 7 days following THVO in this group. A third group of animals also underwent THVO 10 days after ligation of their extrahepatic bile ducts with relief of the obstruction with a Teflon stent immediately after THVO. This group also showed the trend of normalization of liver canalicular and parenchymal enzymes and bilirubin by the end of 7 days. This study demonstrated the feasibility of THVO in rabbits with acute extrahepatic cholestasis whether the extrahepatic biliary obstruction persisted or not.

Busulfan disposition and hepatic veno-occlusive disease in children undergoing bone marrow transplantation

Hepatic veno-occlusive disease (HVOD) is a frequent life-threatening toxicity in patients undergoing bone marrow transplantation (BMT) after the administration of a high-dose busulfan-containing regimen. Recent studies have shown that the morbidity and mortality of HVOD may be reduced in adults by pharmacologically guided dose adjustment of busulfan. We analyzed the pharmacodynamic relationship between busulfan disposition and HVOD in 61 children (median age, 5.9 years) with malignant disease. Busulfan, given at a dose ranging from 16 mg/kg to 600 mg/m2, was combined with one or two other alkylating agents (cyclophosphamide, melphalan, thiotepa). Only 3 patients received the standard busulfan/cyclophosphamide (BUCY) regimen. A total of 24 patients (40%) developed HVOD, which resolved in all cases. A pharmacokinetics study confirmed the previously reported wide interpatient variability in busulfan disposition but did not reveal any significant alteration in children with HVOD. The mean area under the concentration-time curve (AUC) after the first dose of busulfan was higher in patients with HVOD (6,811 +/- 2,943 ng h ml-1) than in patients without HVOD (5,760 +/- 1,891 ng h ml-1., P = 0.10). This difference reflects the higher dose of busulfan given to patients with HVOD. No toxic level could be defined and, moreover, none of the toxic levels identified in adults were relevant. The high incidence of HVOD in children given 600 mg/m2 busulfan may be linked to the use of more intensive than usual high-dose chemotherapy regimens and/or drug interactions. Before the prospective evaluation of busulfan dose adjustment in children, further studies are required to demonstrate firmly the existence of a pharmacodynamic relationship in terms of toxicity and allogeneic engraftment, especially when busulfan is combined with cyclophosphamide. The maximal tolerated and minimal effective AUCs in children undergoing BMT are likely to depend mainly upon the disease, the nature of the combined high-dose regimen, and the type of bone marrow transplant.

Hemodynamics and hepatic energy metabolism in canine model of acute hepatic venous occlusion with mesocaval shunt

The relationship between portal hemodynamics and the energy metabolism of the liver with acute hepatic venous occlusion (HVO) was investigated by assessing the changes in the hepatic blood flow, arterial blood ketone body ratio (AKBR) and adenylate energy charge potential (ECP) of the liver tissue in canine model. Acute HVO was induced by the ligation of both the supra- and infrahepatic inferior vena cava (IVC) over the protruding ends of a heparin-coated polyethylene cannula inserted into the IVC. All dogs with only HVO (n = 5) died within 30 min. HVO dogs with additional mesocaval (MC) shunt (n = 10) survived longer than 7 days, during which time their AKBR were maintained in the normal range (over 1.0). ECP was also maintained above the normal level (over 0.850) during the 28-day period. Along with increasing portal pressure caused by the narrowing of the shunt anastomosis, the hepatic blood flow decrease gradually, resulting in a sudden decrease in AKBR and ECP when the portal pressure increased over 11 mm Hg. It is suggested that the normalization of portal pressure is one of the most important factors for maintaining the hepatic energy metabolism and that MC shunt is an effective therapy for maintaining the function of the liver with HVO, as long as portal pressure can be kept within normal range.

Ground-glass hepatocytes with Lafora body like inclusions--histochemical, immunohistochemical and electronmicroscopic characterization

We report two adult patients whose liver biopsy specimens revealed numerous ground-glass hepatocytes due to inclusions resembling Lafora bodies. The inclusions were large, intracytoplasmic, pale, eosinophilic and kidney-shaped and were periodic acid-Schiff positive and HBsAg negative. Immunoperoxidase studies showed that the inclusions were positive for cytokeratins and alpha 1-antitrypsin. In case 1, the inclusions were not membrane-bound and consisted of secondary lysosomes and degenerate organelles including rough and smooth endoplasmic reticulum. In case 2, electronmicroscopy showed the inclusions were not membrane-bound, but consisted of dense granules, fibrils and vacuoles, with appearances very similar to Lafora bodies. Neither patient had myoclonus or epilepsy. Electronmicroscopy is important in differentiating the type of Lafora body like inclusions found in liver biopsies.

Hepatic veno-occlusive disease after bone marrow transplantation. Immunohistochemical identification of the material within occluded central venules

The authors immunostained autopsy liver tissue from 31 marrow transplant recipients, 19 with hepatic veno-occlusive disease (VOD) and 12 without VOD. A panel of monoclonal and polyclonal antibodies was used to characterize the materials within the occluded venous lesions and to define the location and types of injured cells. Most patients with early VOD (survival less than 50 days, n = 11) had dense periadventitial and intramural immunostaining of terminal hepatic and sublobular central venules (CV) with anti-Factor VIII (9/11) and anti-fibrinogen (4/4) but had no immunostaining with antibody to platelet GPIb. Early VOD patients also had marked loss of Zone 3 hepatocyte cytokeratin (8/9) versus late VOD (1/5) or non-VOD (2/7). Patients with late VOD lesions (n = 8, survival greater than 50 days) had increased collagen within occluded VOD lesions. Type III much greater than Type I, and increased sinusoidal collagens Types I, III, and IV. These studies and other data suggest the following events in the genesis of VOD. Initial injury to endothelium of CV and/or sinusoids and possibly also to Zone 3 hepatocytes triggers the coagulation cascade in the periadventitial zone of CV. The late sequela, collagenous CV occlusion, results from activated mural myofibroblasts and/or embolized Ito cells and hepatocytes.