Serum transaminase elevations as indicators of hepatic injury following the administration of drugs

Clinical significance of liver ischaemia after pancreatic resection

BACKGROUND

Liver ischaemia after pancreatic resection is a rare but potentially serious complication. The aim of this study was to determine the impact of postoperative liver ischaemia after pancreatic resection.

METHODS

All consecutive patients undergoing pancreatic resection between January 2007 and August 2008 in the Department of Surgery in Heidelberg were identified retrospectively from a prospectively collected database and analysed with a focus on postoperative hepatic perfusion failure. Laboratory data, computed tomography (CT) findings, symptoms, therapy and outcome were recorded.

RESULTS

A total of 762 patients underwent pancreatic resection in the study period. Seventeen patients (2·2 per cent) with a postoperative increase in liver enzymes underwent contrast-enhanced CT for suspected liver perfusion failure. The types of perfusion failure were hypoperfusion without occlusion of major hepatic vessels (6 patients) and ischaemia with arterial (5) and/or portal vein (6) involvement. The overall mortality rate was 29 per cent (5 of 17 patients). Therapy included conservative treatment (7), radiological or surgical revascularization and necrosectomy or resection of necrotic liver tissue (10). Outcome varied from full recovery (4 patients) to moderate systemic complications (6) and severe complications (7) including death. Simultaneous involvement of the portal vein and hepatic artery was always fatal.

CONCLUSION

Postoperative liver perfusion failure is a rare but potentially severe complication following pancreatic surgery requiring immediate recognition and, if necessary, radiological or surgical intervention.

Hepatoxicity of major constituents and extractions of Radix Polygoni Multiflori and Radix Polygoni Multiflori Praeparata

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Polygoni Multiflori (RPM) and Radix Polygoni Multiflori Praeparata (RPMP) were traditionally widely used as Chinese herbal medicine. However, liver adverse reactions caused by RPM or RPMP were frequently reported all around the world recent years. The aim of this study was to study the cytotoxicities of RPM, RPMP and their major constituents on human liver cell L-02 simultaneously.

MATERIALS AND METHODS

Multi-assays, including MTT assay, neutral red uptake (NRU) assay, LDH leakage percentage and liver enzyme secretion (AST, ALT and ALP) were used. Cytotoxicities of major chemical constituents of RPM, 2, 3, 5, 4'-tetrahydroxy-stilbene-2-O-β-D-glucoside (TSG), physcion and emodin, were tested. The cytotoxicities of water, 50% ethanol and 95% ethanol extractions of RPM and RPMP were tested. HPLC-DAD analysis was carried to reveal the content change of TSG, physcion and emodin after the processing procedure.

RESULTS

The TD(50) of TSG, physcion and emodin in MTT assay were >10,000 μM, 2853.61 μM and 520.37 μM. In the NRU assay, the TD(50) of TSG, physcion and emodin were much smaller (1401.53 μM, 1140.00 μM, and 3.80 μM). Emodin induced much severe liver enzyme secretion than TSG and physcion. Cell proliferation and LDH leakage rate showed no difference between RPM and RPMP extractions, but ALP, AST and ALT secretions in RPMP extractions were significant lower than that of PMR groups. Water extractions of RPM and RPMP were less toxic than any other solvent in most of the assays. Positive correlation was found between the TSG/emodin ratio and MTT survival rate. The emodin/physcion ratio also showed positive correlation with the LDH leakage percentage.

CONCLUSIONS

In conclusion, Radix Polygonum multiflorum and Radix Polygonum multiflorum Praeparata were not liver injure inducing in our in vitro assays. However, the processing produce of RPM could reduce its effect on both cell proliferation and enzyme secretion of liver cell. Judging from cell proliferation, integrity of cell membrane and enzyme secretion, three major chemical constituents of RPM: TSG, physcion and emodin showed no, moderate and severe cytotoxicity against human liver cell line L-02 respectively. Chemical constituents-cytotoxicity relationship investigation revealed that TSG and physcion probably had attenuating effect to emodin. The attenuating mechanisms were still under investigation.

Rapid development of new protein biosensors utilizing peptides obtained via phage display

There is a consistent demand for new biosensors for the detection of protein targets, and a systematic method for the rapid development of new sensors is needed. Here we present a platform where short unstructured peptides that bind to a desired target are selected using M13 phage display. The selected peptides are then chemically synthesized and immobilized on gold, allowing for detection of the target using electrochemical techniques such as electrochemical impedance spectroscopy (EIS). A quartz crystal microbalance (QCM) is also used as a diagnostic tool during biosensor development. We demonstrate the utility of this approach by creating a novel peptide-based electrochemical biosensor for the enzyme alanine aminotransferase (ALT), a well-known biomarker of hepatotoxicity. Biopanning of the M13 phage display library over immobilized ALT, led to the rapid identification of a new peptide (ALT5-8) with an amino acid sequence of WHWRNPDFWYLK. Phage particles expressing this peptide exhibited nanomolar affinity for immobilized ALT (K(d,app) = 85±20 nM). The newly identified ALT5-8 peptide was then chemically synthesized with a C-terminal cysteine for gold immobilization. The performance of the gold-immobilized peptides was studied with cyclic voltammetry (CV), QCM, and EIS. Using QCM, the sensitivity for ALT detection was 8.9±0.9 Hz/(µg/mL) and the limit of detection (LOD) was 60 ng/mL. Using EIS measurements, the sensitivity was 142±12 impedance percentage change %/(µg/mL) and the LOD was 92 ng/mL. In both cases, the LOD was below the typical concentration of ALT in human blood. Although both QCM and EIS produced similar LODs, EIS is preferable due to a larger linear dynamic range. Using QCM, the immobilized peptide exhibited a nanomolar dissociation constant for ALT (K(d) = 20.1±0.6 nM). These results demonstrate a simple and rapid platform for developing and assessing the performance of sensitive, peptide-based biosensors for new protein targets.

Preclinical safety assessment: current gaps, challenges, and approaches in identifying translatable biomarkers of drug-induced liver injury

Currently, no serum biomarkers, including the biochemical gold standard alanine aminotransferase, can differentiate drug-induced from non-drug-related liver injury, can differentiate liver injury mediated by a specific drug or mechanism, or can accurately predict the progression and outcome of hepatic injury. Efforts have been made by veterinary clinical pathologists, toxicologists, and other scientists to address the gaps in hepatic biomarkers faced during drug development; although there have been no breakthroughs, several novel biomarker candidates have been identified. Efforts to address the gaps in translatable hepatic biomarkers and the challenges and hurdles faced during this process are highlighted in this review.

Liver function alterations after laparoscopy-assisted gastrectomy for gastric cancer and its clinical significance

AIM: To evaluate the factors associated with liver function alterations after laparoscopy-assisted gastrectomy (LAG) for gastric cancer.

METHODS: We collected the data of gastrectomy patients with gastric cancer and divided them into 2 groups: open gastrectomy (OG) and LAG. We also collected the data of patients with colon cancer to evaluate the effect of liver manipulations during surgery on liver function alterations. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, and alkaline phosphatase were measured on the preoperative day and postoperative day 1 (POD1), POD3, POD5, and POD7.

RESULTS: No changes in liver function were observed after the operation in patients with colon cancer (n = 121). However, in gastric cancer patients (n = 215), AST and ALT levels increased until POD5 compared to those in colon cancer patients and these findings were observed both in the LAG and OG without a significant difference except at POD1. The mean hepatic enzyme levels at POD1 in the LAG group were significantly higher than those in the OG group (P = 0.047 for AST and P = 0.039 for ALT). The factors associated with elevated ALT on POD1 in patients with gastric cancer were body mass index (P < 0.001), operation time (P < 0.001), intraoperative hepatic injury (P = 0.048), and ligation of an aberrant left hepatic artery (P = 0.052) but not type of operation (OG vs LAG, P = 0.094).

CONCLUSION: We conclude that the liver function alteration after LAG may have been caused by direct liver manipulation or aberrant hepatic artery ligation rather than the CO₂ pneumoperitoneum.

Dietary free oleic and linoleic acid enhances neutrophil function and modulates the inflammatory response in rats

The high ingestion of oleic (OLA) and linoleic (LNA) acids by Western populations, the presence of inflammatory diseases in these populations, and the importance of neutrophils in the inflammatory process led us to investigate the effects of oral ingestion of unesterified OLA and LNA on rat neutrophil function. Pure OLA and LNA were administered by gavage over 10 days. The doses used (0.11, 0.22 and 0.44 g/kg of body weight) were based on the Western consumption of OLA and LNA. Neither fatty acid affected food, calorie or water intake. The fatty acids were not toxic to neutrophils as evaluated by cytometry using propidium iodide (membrane integrity and DNA fragmentation). Neutrophil migration in response to intraperitoneal injection of glycogen and in the air pouch assay, was elevated after administration of either OLA or LNA. This effect was associated with enhancement of rolling and increased release of the chemokine CINC-2alphabeta. Both fatty acids elevated L-selectin expression, whereas no effect on beta(2)-integrin expression was observed, as evaluated by flow cytometry. LNA increased the production of proinflammatory cytokines (IL-1beta and CINC-2alphabeta) by neutrophils after 4 h in culture and both fatty acids decreased the release of the same cytokines after 18 h. In conclusion, OLA and LNA modulate several functions of neutrophils and can influence the inflammatory process.

Diagnostic performance of traditional hepatobiliary biomarkers of drug-induced liver injury in the rat

Nonclinical studies provide the opportunity to anchor biochemical with morphologic findings; however, liver injury is often complex and heterogeneous, confounding the ability to relate biochemical changes with specific patterns of injury. The aim of the current study was to compare diagnostic performance of hepatobiliary markers for specific manifestations of drug-induced liver injury in rat using data collected in a recent hepatic toxicogenomics initiative in which rats (n = 3205) were given 182 different treatments for 4 or 14 days. Diagnostic accuracy of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (Tbili), serum bile acids (SBA), alkaline phosphatase (ALP), gamma glutamyl transferase (GGT), total cholesterol (Chol), and triglycerides (Trig) was evaluated for specific types of liver histopathology by Receiver Operating Characteristic (ROC) analysis. To assess the relationship between biochemical and morphologic changes in the absence of hepatocellular necrosis, a second ROC analysis was performed on a subset of rats (n = 2504) given treatments (n = 152) that did not cause hepatocellular necrosis. In the initial analysis, ALT, AST, Tbili, and SBA had the greatest diagnostic utility for manifestations of hepatocellular necrosis and biliary injury, with comparable magnitude of area under the ROC curve and serum hepatobiliary marker changes for both. In the absence of hepatocellular necrosis, ALT increases were observed with biochemical or morphologic evidence of cholestasis. In both analyses, diagnostic utility of ALP and GGT for biliary injury was limited; however, ALP had modest diagnostic value for peroxisome proliferation, and ALT, AST, and total Chol had moderate diagnostic utility for phospholipidosis. None of the eight markers evaluated had diagnostic value for manifestations of hypertrophy, cytoplasmic rarefaction, inflammation, or lipidosis.

Potential relationships between transaminase abnormality and valproic acid clearance or serum carnitine concentrations in Japanese epileptic patients

This study tested the hypothesis that the determinants of mild liver injury are prerequisites for more severe idiosyncratic hepatotoxicity. This study verified whether the possible risk factors for rare idiosyncratic valproic acid (VPA)-induced hepatotoxicity, VPA clearance and/or serum carnitine concentrations are common to those for a mild elevation in transaminases in VPA-treated patients. VPA clearance was calculated in 172 Japanese patients with epilepsy, using a non-linear mixed-effects regression program. Carnitine concentrations were determined in a subset of 60 patients. The relationships between VPA clearance, carnitine concentration and levels of transaminases and ammonia were evaluated by Pearson's correlation coefficients. The final model of VPA apparent clearance (CL/F) was as follows: CL/F (L h−1) = 0.012 × (BW/40)0.34 × dose0.55 × 0.90gender × 1.32PHT × 1.11CBZ × 1.12PB, where BW = total body weight (kg); gender = 1 if female, 0 if male; PHT/CBZ/PB = 1 if phenytoin, carbamazepine, or phenobarbital, respectively, is coadministrated, otherwise 0. Either a higher VPA clearance or acyl/free carnitine ratio and a lower total and/or free carnitine concentration, but not VPA concentration, were associated with the mild elevation in transaminases or ammonia. These results support the initial hypothesis, while also helping to clarify the mechanism of severe idiosyncratic hepatotoxicity with VPA.

Efficacy of favipiravir (T-705) and T-1106 pyrazine derivatives in phlebovirus disease models

Several studies have reported favipiravir (T-705) to be effective in treating a number of viral diseases modeled in rodent systems. Notably, the related pyrazine derivative, T-1106, was found to be more effective than T-705 in treating yellow fever virus infection in hamsters. Based on these findings, we hypothesized that T-1106 may be more effective in treating hepatotropic Punta Toro virus (PTV, Phlebovirus) infection in rodents. In cell culture, the inhibitory concentrations of the compounds against various phleboviruses ranged from 3 to 55microM for T-705 and from 76 to 743microM for T-1106. In PTV-challenged hamsters, a model that generally presents with high liver viral loads, T-1106 was more effective at reducing mortality. However, in mice infected with PTV, a model wherein systemic infection is more prominent, the greater efficacy exhibited by T-1106 in the hamster system was not apparent. In contrast, T-705 was superior in preventing mortality in hamsters challenged with Pichinde virus (PICV, Arenavirus), an infection characterized as diffuse and pantropic. Remarkably, T-1106 has proven more active in vivo than would have been expected from our cell culture results, and our in vivo findings suggest that it is more effective in infections characterized predominantly by high levels of hepatic viral burden.

Punta Toro virus (Bunyaviridae, Phlebovirus) infection in mice: strain differences in pathogenesis and host interferon response

The Adames strain of Punta Toro virus (PTV-A, Bunyaviridae, Phlebovirus) causes an acute lethal disease in hamsters and mice. The Balliet strain of the virus (PTV-B) is generally considered to be avirulent. The difference in hamster susceptibility is likely due to the ability of PTV-A to suppress interferon (IFN)-beta similarly to that described for Rift Valley fever virus. Here we investigated strain differences in PTV pathogenesis and the IFN response in mice. Although PTV-B infection in mice did not induce systemic IFN-beta release, primary macrophages produced dramatically higher levels when exposed to the virus in culture. The importance of IFN in resistance to PTV infection was borne out in studies employing STAT-1 knock-out mice. Also, a number of genes specific to IFN response pathways were upregulated in PTV-B-infected macrophages. Our findings provide new insights into the type I IFN response during PTV infection in the mouse model of phleboviral disease.

Determination of enzymatic source of alanine aminotransferase activity in serum from dogs with liver injury

INTRODUCTION

Increase of serum alanine aminotransferase (ALT) activity is widely used as a surrogate marker for tissue damage. Two ALT isoforms, ALT1 and ALT2, have been cloned recently in mammals. The study investigated the source of elevated ALT activity in serum of dogs treated with a hepatotoxic compound.

METHODS

ALT activity was measured by enzyme assay. Immunoblot analysis was performed using generated specific peptide antibodies against dog ALTs. LC-MS/MS-based proteomics analysis was conducted to independently identify dog ALT peptides. Serum samples immunodepleted of major serum components by Seppro IgY-D11 microbead spin column were evaluated by the immunoblot analysis, and compared with those of the ALT activity.

RESULTS

Involvement of ALT enzyme(s) is consistent with the following observations: 1) all the substrates (L-alanine and alpha-ketoglutarate) were required for serum ALT activity as purified porcine ALT1 needed for activity, 2) serum ALT activity was inhibited by L-cycloserine, a known ALT inhibitor, and 3) apparent Km value for the ALT reaction catalyzed by the serum, liver, and skeletal muscle was roughly similar. Immunoblot analysis showed that ALT1 was detected in liver and both ALTs were detected in the skeletal muscle. The relative expression level of ALTs was -: liver ALT1>skeletal muscle ALT1>skeletal muscle ALT2. LC-MS/MS-based proteomics analysis gave similar results. Immunoblot analysis of the depleted serum samples revealed the presence of ALT1 in compound-treated dogs. Intensity of the ALT1 band detected in the sera correlated well with the ALT activity measured by the enzyme assay.

DISCUSSION

Based on these findings, we conclude that the elevation of serum ALT activity in dogs with liver injury is attributed to elevation of ALT1 protein level in serum. The methodology to directly detect ALT proteins in serum could be a tool to facilitate our understanding of biological and toxicological significance of the ALT isoenzymes.

Intestinal glucose uptake protects liver from lipopolysaccharide and D-galactosamine, acetaminophen, and alpha-amanitin in mice

We have recently observed that oral administration of D-glucose saves animals from lipopolysaccharide (LPS)-induced death. This effect is the likely consequence of glucose-induced activation of the sodium-dependent glucose transporter-1. In this study, we investigated possible hepatoprotective effects of glucose-induced, sodium-dependent, glucose transporter-1 activation. We show that oral administration of D-glucose, but not of either D-fructose or sucrose, prevents LPS-induced liver injury, as well as liver injury and death induced by an overdose of acetaminophen. In both of these models, physiological liver morphology is maintained and organ protection is confirmed by unchanged levels of the circulating markers of hepatotoxicity, such as alanine transaminase or lactate dehydrogenase. In addition, D-glucose was found to protect the liver from alpha-amanitin-induced liver injury. In this case, in contrast to the previously described models, a second signal had to be present in addition to glucose to achieve protective efficacy. Toll-like receptor 4 stimulation that was induced by low doses of LPS was identified as such a second signal. Eventually, the protective effect of orally administered glucose on liver injury induced by LPS, overdose of acetaminophen, or alpha-amanitin was shown to be mediated by the anti-inflammatory cytokine interleukin-10. These findings, showing glucose-induced protective effects in several animal models of liver injury, might be relevant in view of possible therapeutic interventions against different forms of acute hepatic injury.

Effects of simvastatin 40 mg daily on muscle and liver adverse effects in a 5-year randomized placebo-controlled trial in 20,536 high-risk people

BACKGROUND

Simvastatin reduces cardiovascular mortality and morbidity but, as with other HMG-CoA reductase inhibitors, can cause significant muscle toxicity and has been associated with elevations of liver transaminases.

METHODS

Muscle and liver adverse effects of simvastatin 40 mg daily were evaluated in a randomized placebo-controlled trial involving 20,536 UK patients with vascular disease or diabetes (in which a substantial reduction of cardiovascular mortality and morbidity has previously been demonstrated).

RESULTS

The excess incidence of myopathy in the simvastatin group was < 0.1% over the 5 years of the trial, and there were no significant differences between the treatment groups in the incidence of serious hepatobiliary disease.

CONCLUSION

Among the many different types of high-risk patient studied (including women, older individuals and those with low cholesterol levels), there was a very low incidence (< 0.1%) of myopathy during 5 years treatment with simvastatin 40 mg daily. The risk of hepatitis, if any, was undetectable even in this very large long-term trial. Routine monitoring of liver function tests during treatment with simvastatin 40 mg is not useful.

Diminished acute phase response and increased hepatic inflammation of aged rats in response to intraperitoneal injection of lipopolysaccharide

Aging is associated with a deterioration of the acute phase response to inflammatory challenges. However, the nature of these defects remains poorly defined. We analyzed the hepatic inflammatory response after intraperitoneal administration of lipopolysaccharide (LPS) given to Fisher 344 rats aged 6, 15, and 22-23 months. Induction of the acute phase proteins (APPs), haptoglobin, alpha-1-acid glycoprotein, and T-kininogen was reduced and/or retarded with aging. Initial induction of interleukin-6 in aged rats was normal, but the later response was increased relative to younger counterparts. An exacerbated hepatic injury was observed in aged rats receiving LPS, as evidenced by the presence of multiple microabscesses in portal tracts, confluent necrosis, higher neutrophil accumulation, and elevated serum levels of alanine aminotransferase, relative to younger animals. Our results suggest that aged rats displayed a reduced expression of APPs and increased hepatic injury in response to the inflammatory insult.

The early effects of short-term dexamethasone administration on hepatic and serum alanine aminotransferase in the rat

Dexamethasone (DEXA) administration has been associated with serum alanine aminotransferase (ALT) elevations that may result from enhanced ALT expression. The aim of our current study was to compare liver vs. serum ALT activity and to examine the onset of any hepatocellular changes. Groups of 4 male Sprague-Dawley rats were administered a single dose of DEXA or corn oil at 12, 16, and 24 h prior to euthanasia or once-daily for 2, 3, or 4 days. All (nonfasted) rats were necropsied together on Day 5. While DEXA incrementally increased liver ALT activity in the 1-, 2-, 3-, and 4-day treatment groups (maximal, 3.7-fold), liver aspartate aminotransferase (AST) never exceeded 1.4-fold over control. Significant hepatic glycogen elevations were detected after DEXA treatment, which correlated with microscopic observations. Serum ALT, AST, sorbitol dehydrogenase, and glutamate dehydrogenase (GLDH) increased after 2, 3, and 4 days of DEXA dosing (1.3-10.3-fold). DEXA-related necropsy findings included pale livers consistent with glycogen deposition. The relative percent liver to body weight was elevated in all DEXA-treated rats. Hepatocellular necrosis was observed in 1/4 rats at 12 h, 2/4 rats at 2 days, 4/4 rats at 3 days, and 3/4 rats at 4 days. DEXA treatment <2 days failed to produce consistent evidence of hepatic injury, as detected by serum biomarkers and pathology assessment. However, early DEXA treatment did correlate with apparent ALT induction. Ultimately, this may explain some early asymptomatic serum ALT elevations seen clinically.

Drug-virus interaction: effect of administration of recombinant adenoviruses on the pharmacokinetics of docetaxel in a rat model

Modern cancer therapy combines recombinant viruses with traditional chemotherapeutic agents that are metabolized by hepatic cytochrome P450 3A4 (CYP3A4). A single dose of recombinant adenovirus (Ad) expressing beta-galactosidase (AdlacZ) significantly alters CYP3A2, the correlate of CYP3A4, in rats for 14 days. Recombinant adenovirus expressing human p53 (Adp53) also suppresses CYP3A2. Plasma clearance of docetaxel (DTX) in animals given AdlacZ (3.38 ± 0.22 L/h/kg) was significantly lower than that of those given DTX alone (6.41 ± 1.10 L/h/kg, p≤0.05). Area under the plasma concentration-time curve of DTX in rats given AdlacZ (2,987.37 ± 197.97 ng/ml/h) was significantly greater than those given drug alone (1,666.59 ± 317.04 ng/ml/h, p≤0.05). Both viruses prolonged DTX half-life (t_1/2). Ad infection may cause significant variability in the pharmacokinetics and pharmacodynamics of anti-cancer agents and should be considered when designing therapeutic regimens for patients with viral infection and those enrolled in clinical trials employing recombinant viruses.

Prophylaxis with cationic liposome-DNA complexes protects hamsters from phleboviral disease: importance of liposomal delivery and CpG motifs

Cationic liposome-DNA complexes (CLDC) are cationic/neutral lipid carriers complexed with plasmid DNA that when administered systemically results in a robust T(H)1 cytokine response. CLDC have been shown to be effective in prophylaxis and therapeutic treatment of animal models of viral disease. To determine the contribution of liposomal delivery and CpG content of the plasmid DNA to the efficacy of CLDC; plasmid, CpG-free plasmid DNA, or CpG-containing oligodeoxynucleotides (ODN) with and without liposomes, as well as poly(I:C(12)U), were evaluated for their ability to elicit protection against lethal Punta Toro virus (PTV, Bunyaviridae, phlebovirus) challenge in hamsters. CLDC-containing plasmid significantly improved survival, decreased systemic and liver viral loads, and reduced liver damage due to progression of viral infection. Mouse-reactive ODNs complexed with liposomes failed to protect hamsters, whereas ODNs known to cross-react with human and mouse (CpG 2006) or non-liposomal poly(I:C(12)U) showed survival benefit but did not limit liver injury. Liposomes complexed with a non-CpG motif-containing plasmid reduced liver viral load and tissue damage, but did not protect hamsters from death. To evaluate the mechanisms of the enhanced activity of CLDC, microarray experiments examined differences in the gene expression profile. The results suggest a broad T(H)1 response elicited by liposomal delivery of a diverse sequence containing CpG and non-CpG elements may be a more effective antiviral treatment than other nucleic acid based immunotherapeutics.

Diallyl trisulfide (DATS) effectively attenuated oxidative stress-mediated liver injury and hepatic mitochondrial dysfunction in acute ethanol-exposed mice

The protective effects of diallyl trisulfide (DATS) on acute ethanol-induced liver injury were investigated. Mice were pretreated with DATS (30mg/kgbw) for 7d before being exposed to ethanol (4.8g/kgbw). The biochemical indices (aspartate amino transferase, AST; alanine amino transferase, ALT; triglyceride, TG) were examined to evaluate the protective effects. Mitochondria were isolated for the mitochondrial permeability transition (MPT), membrane potential (DeltaPsi(m)) and adenosine nucleotide pool assay. The lipid peroxidation (malondialdehyde, MDA), non-enzymatic antioxidant (glutathione, GSH) and enzymatic antioxidants (superoxide dismutase, SOD; catalase, CAT; glutathione reductase, GR; glutathione peroxidase, GSH-Px) were measured both in the liver homogenate and isolated mitochondria. Acute ethanol exposure resulted in the significant increase of the ALT, AST and TG levels and hepatic mitochondria dysfunction shown as MPT, and the decreases of DeltaPsi(m), ATP and energy charge (EC). However, DATS pretreatment dramatically attenuated these adverse effects. Beside this, DATS was found to significantly inhibit the increase of the hepatic and mitochondrial MDA levels, which were decreased by 33.3% (P<0.01) and 39.0% (P<0.01), respectively. In addition, DATS pretreatment markedly suppressed the ethanol-induced decrease of the hepatic GSH level and increased the mitochondrial GSH level. Moreover, the activities of the hepatic antioxidant enzymes (SOD, CAT, and GR) and the mitochondrial antioxidant enzymes (SOD, GR, and GSH-Px) were significantly boosted. Thus, we concluded that DATS dramatically attenuated acute ethanol-induced liver injury and mitochondrial dysfunction. The increase of the hepatic and mitochondrial GSH levels and the elevation of the antioxidant enzymes activities should account for the preventive effects.

Expression, purification, and initial characterization of human alanine aminotransferase (ALT) isoenzyme 1 and 2 in High-five insect cells

Alanine aminotransferase (ALT) is a key enzyme for gluconeogenesis as well as a widely used serum marker for liver injury. We have identified two ALT isoenzymes, ALT1 and ALT2, which are encoded by separate genes. In this study, we described the expression, purification and initial characterization of human ALT1 and ALT2 proteins in High-five insect cells. Human ALT1 and ALT2 were expressed as His-tagged fusion proteins by recombinant baculovirus in insect cells and purified into homogeneity in one step by using immobilized Ni2+-affinity chromatography. Tag-free ALT1 and ALT2 were obtained by cleavage of enterokinase digestion and used for initial characterization of the enzymes. The specific ALT activity of purified fusion or His-tag-removed ALT1 was about 15-fold higher than that of ALT2 and their enzymatic activities decreased quickly at 37 degrees C and -20 degrees C, but were well preserved at -80 degrees C. Nevertheless, the ALT1 and ALT2 activities remained stable in a buffer containing 25% glycerol. The pH profile was similar between hALT1 and hALT2 in that both enzymes remained fully active between pH 6.5 and 8.0. The purified ALT recombinant proteins can not only be used as a reference protein standard for the ALT assay in clinical chemistry, but also will be useful for understanding the biochemical and biological significance of the isoenzymes and for developing ALT isoform-specific assays for clinical or preclinical diagnostic use.

Identification of novel toxicity-associated metabolites by metabolomics and mass isotopomer analysis of acetaminophen metabolism in wild-type and Cyp2e1-null mice

CYP2E1 is recognized as the most important enzyme for initiation of acetaminophen (APAP)-induced toxicity. In this study, the resistance of Cyp2e1-null mice to APAP treatment was confirmed by comparing serum aminotransferase activities and blood urea nitrogen levels in wild-type and Cyp2e1-null mice. However, unexpectedly, profiling of major known APAP metabolites in urine and serum revealed that the contribution of CYP2E1 to APAP metabolism decreased with increasing APAP doses administered. Measurement of hepatic glutathione and hydrogen peroxide levels exposed the importance of oxidative stress in determining the consequence of APAP overdose. Subsequent metabolomic analysis was capable of constructing a principal components analysis (PCA) model that delineated a relationship between urinary metabolomes and the responses to APAP treatment. Urinary ions high in wild-type mice treated with 400 mg/kg APAP were elucidated as 3-methoxy-APAP glucuronide (VII) and three novel APAP metabolites, including S-(5-acetylamino-2-hydroxyphenyl)mercaptopyruvic acid (VI, formed by a Cys-APAP transamination reaction in kidney), 3,3'-biacetaminophen (VIII, an APAP dimer), and a benzothiazine compound (IX, originated from deacetylated APAP), through mass isotopomer analysis, accurate mass measurement, tandem mass spectrometry fragmentation, in vitro reactions, and chemical treatments. Dose-, time-, and genotype-dependent appearance of these minor APAP metabolites implied their association with the APAP-induced toxicity and potential biomarker application. Overall, the oxidative stress elicited by CYP2E1-mediated APAP metabolism might significantly contribute to APAP-induced toxicity. The combination of genetically modified animal models, mass isotopomer analysis, and metabolomics provides a powerful and efficient technical platform to characterize APAP-induced toxicity through identifying novel biomarkers and unraveling novel mechanisms.

The current state of serum biomarkers of hepatotoxicity

The level of serum alanine aminotransferase (ALT) activity reflects damage to hepatocytes and is considered to be a highly sensitive and fairly specific preclinical and clinical biomarker of hepatotoxicity. However, an increase in serum ALT activity level has also been associated with other organ toxicities, thus, indicating that the enzyme has specificity beyond liver in the absence of correlative histomorphologic alteration in liver. Thus, unidentified non-hepatic sources of serum ALT activity may inadvertently influence the decision of whether to continue development of a novel pharmaceutical compound. To assess the risk of false positives due to extraneous sources of serum ALT activity, additional biomarkers are sought with improved specificity for liver function compared to serum ALT activity alone. Current published biomarker candidates are reviewed herein and compared with ALT performance in preclinical and on occasion, clinical studies. An examination of the current state of hepatotoxic biomarkers indicates that serum F protein, arginase I, and glutathione-S-transferase alpha (GSTalpha) levels, all measured by ELISA, may show utility, however, antibody availability and high cost per run may present limitations to widespread applicability in preclinical safety studies. In contrast, the enzymatic markers sorbitol dehydrogenase, glutamate dehydrogenase, paraxonase, malate dehydrogenase, and purine nucleoside phosphorylase are all readily measured by photometric methods and use reagents that work across preclinical species and humans and are commercially available. The published literature suggests that these markers, once examined collectively in a large qualification study, could provide additional information relative to serum ALT and aspartate aminotransferase (AST) values. Since these biomarkers are found in the serum/plasma of treated humans and rats, they have potential to be utilized as bridging markers to monitor acute drug-induced liver injury in early clinical trials.

How shall we use the proteomics toolbox for biomarker discovery?

Biomarker discovery for clinical purposes is one of the major areas in which proteomics is used. However, despite considerable effort, the successes have been relatively scarce. In this perspective paper, we try to highlight and analyze the main causes for this limited success, and to suggest alternate strategies, which will avoid them, without eluding the foreseeable weak points of these strategies. Two major strategies are analyzed, namely, the switch from body fluids to cell and tissues for the initial biomarker discovery step or, if body fluids must be analyzed, the implementation of highly selective protein selection strategies.

Influence of Different Atropine Therapy Strategies on Fenthion-Induced Organ Dysfunction in Rats

We studied the influence of dose and timing of atropine therapy on fenthion-induced organ dysfunction. Thirty-six rats were randomized into six groups. All rats in the five groups except the control group were intoxicated with fenthion. The high-dose atropine group received 2 mg/kg of atropine, whereas the low-dose group received 100 microg/kg of atropine every hour for 24 hr. One group received 2 mg/kg of atropine in the first 4 hr of intoxication while the other group received 2 mg/kg of atropine in the last 4 hr before killed, which for all rats was 24 hr after intoxication. Pseudocholinesterase and aspartate aminotransferase and alanine aminotransferase levels and histopathological markers of lung, brain and liver were studied. None of our atropine therapy strategies in this study totally prevented harm on the three organs. Although the high dose of atropine administered for 24 hr had the least harmful markers for lung, it also had the most harmful markers for brain and liver. We did not succeed in finding a unique therapy strategy in our models beneficial for all studied organs in fenthion intoxication in rats. Atropine administration strategy should be oriented for the most affected organ pathology in fenthion intoxication.

An official ATS statement: hepatotoxicity of antituberculosis therapy

Drug-induced liver injury (DILI) is a problem of increasing significance, but has been a long-standing concern in the treatment of tuberculosis (TB) infection. The liver has a central role in drug metabolism and detoxification, and is consequently vulnerable to injury. The pathogenesis and types of DILI are presented, ranging from hepatic adaptation to hepatocellular injury. Knowledge of the metabolism of anti-TB medications and of the mechanisms of TB DILI is incomplete. Understanding of TB DILI has been hampered by differences in study populations, definitions of hepatotoxicity, and monitoring and reporting practices. Available data regarding the incidence and severity of TB DILI overall, in selected demographic groups, and in those coinfected with HIV or hepatitis B or C virus are presented. Systematic steps for prevention and management of TB DILI are recommended. These include patient and regimen selection to optimize benefits over risks, effective staff and patient education, ready access to care for patients, good communication among providers, and judicious use of clinical and biochemical monitoring. During treatment of latent TB infection (LTBI) alanine aminotransferase (ALT) monitoring is recommended for those who chronically consume alcohol, take concomitant hepatotoxic drugs, have viral hepatitis or other preexisting liver disease or abnormal baseline ALT, have experienced prior isoniazid hepatitis, are pregnant or are within 3 months postpartum. During treatment of TB disease, in addition to these individuals, patients with HIV infection should have ALT monitoring. Some experts recommend biochemical monitoring for those older than 35 years. Treatment should be interrupted and, generally, a modified or alternative regimen used for those with ALT elevation more than three times the upper limit of normal (ULN) in the presence of hepatitis symptoms and/or jaundice, or five times the ULN in the absence of symptoms. Priorities for future studies to develop safer treatments for LTBI and for TB disease are presented.

Hepatoprotective effect of manual acupuncture at acupoint GB34 against CCl4-induced chronic liver damage in rats

AIM: To investigate the hepatoprotective effect of manual acupuncture at Yanglingquan (GB34) on CCl₄-induced chronic liver damage in rats.

METHODS: Rats were injected intraperitoneally with CCl₄ (1 mL/kg) and treated with manual acupuncture using reinforcing manipulation techniques at left GB34 (Yanglingquan) 3 times a week for 10 wk. A non-acupoint in left gluteal area was selected as a sham point. To estimate the hepatoprotective effect of manual acupuncture at GB34, measurement of liver index, biochemical assays including serum ALT, AST, ALP and total cholesterol, histological analysis and blood cell counts were conducted.

RESULTS: Manual acupuncture at GB34 reduced the liver index, serum ALT, AST, ALP and total cholesterol levels as compared with the control group and the sham acupuncture group. It also increased and normalized the populations of WBC and lymphocytes.

CONCLUSION: Manual acupuncture with reinforcing manipulation techniques at left GB34 reduces liver toxicity, protects liver function and liver tissue, and normalizes immune activity in CCl₄-intoxicated rats.

Induction of endogenous pathways by antiepileptics and clinical implications

The aim of this study was to review modifications of the endogenous pathways (e.g. enzyme elevations, normal body constituent depletion or higher formation/excretion of endogenous metabolites) which could be ascribed to enzyme induction by antiepileptic drugs (AEDs). Information on older (e.g. phenobarbital, phenytoin and carbamazepine) and newer drugs (where information is available) is discussed together with clinical implications. The enzymes involved in the endogenous pathways and induced by the AEDs will not be limited to the hepatic microsomal enzymes; extrahepatic enzymes and/or enzymes present in other subcellular fractions will also be discussed, if pertinent. The induction of endogenous pathways by AEDs has been taken into account in the past, but much less emphasis has been given compared with the extensive literature on induction by AEDs of the metabolism of concomitantly administered drugs, either of the same or of different classes. Not all of the endogenous pathways examined and induced by AEDs appear to result in serious clinical consequences (e.g. induction of hepatic ALP, increased excretion of d-glucaric acid or of 6 beta-hydroxycortisol). In some cases, induction of some pathways (e.g. increase of high-density lipoprotein cholesterol or of conjugated bilirubin) might even be a beneficial side-effect, however enzyme induction is considered rather a detrimental aspect for an AED, as induction is generally a broad and a non-specific phenomenon. The new AEDs have generally less induction potential than the older agents. Yet some (felbamate, topiramate, oxcarbazepine and lamotrigine) have the potential for inducing enzymes, whereas others (levetiracetam, gabapentin and vigabatrin) appear to be completely devoid of enzyme inducing characteristics, at least as far as the enzymes investigated are concerned.

Changes in nevirapine plasma concentrations over time and its relationship with liver enzyme elevations

Liver enzyme elevations are frequently seen in patients treated with nevirapine (NVP). Both elevated NVP plasma levels and hepatitis C virus (HCV) infection seem to favor the development of NVP-related liver toxicity. We have examined variation on NVP C(trough) over time, as well as the impact of NVP C(trough) concentrations and the role of chronic hepatitis C on the incidence of liver enzyme elevations over a 48-week study period in HIV-infected patients on NVP therapy. Thirty-seven patients who initiated a triple regimen of NVP (200 mg bid) plus two nucleoside reverse transcriptase inhibitors (NRTI) were analyzed. A significant increase in serum transaminase levels occurred progressively over time. However, no significant variations in NVP plasma C(trough) were noticed in 48 weeks. In total population, maximum fold increase (MFI) in serum AST, ALT, and GGT was correlated with 24 week NVP C(trough). In HCV+ subjects, 12-week NVP C(trough) was closely correlated with maximum transaminase elevations, whereas in HCV- patients, 24-week concentrations were correlated with maximum transaminase increase. However, no differences in either NVP plasma C(trough) or in MFI in transaminase levels could be determined when comparing patients with and without hepatitis C at any time point.

In silico prediction of drug safety: despite progress there is abundant room for improvement

Predictive models for drug safety are crucial for helping to avoid costly late-stage failures. We review recent work on models for genotoxicity, liver toxicity, CYP450 inhibition and cardiotoxicity. These models have improved somewhat in recent years, and research has expanded into new frontiers, such as the prediction of liver toxicity. However, much more needs to be done.:

Hepatic injury, liver monitoring and the beta-interferons for multiple sclerosis

This review explores the salient issues surrounding liver injury and liver monitoring associated with beta-interferon (IFNB) treatment for multiple sclerosis (MS). Post-marketing studies have found a higher proportion of IFNB-treated MS patients with elevated aminotransferases than reported in the pivotal clinical trials. Although the risk of severe liver injury appears small, the true incidence is unknown. Post-marketing studies have shown that the greatest period of risk for the development of liver test abnormalities appears to be in the first year of IFNB treatment. The risk also increases with the more frequently administered, higher-dosage IFNBs. Males are more likely than females to develop elevated aminotransferases (> upper normal limit), although females appear at a greater risk of severe liver injury. Of the commonly used biochemical liver tests, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP) and bilirubin appear the most useful for routine monitoring of IFNB treatment. Whilst many other factors can affect liver test results, including obesity, alcohol, concomitant medications, co-morbidities and theoretically even MS itself, regular liver testing both prior and during IFNB therapy might help minimise Type A or dose/frequency dependent aminotransferase elevations. However, testing will probably not prevent the Type B idiosyncratic reactions which can result in severe hepatic injury; hence patients need to be aware, and to report hepatic side effects promptly.

Comparative anti-inflammatory activities of antagonists to C3a and C5a receptors in a rat model of intestinal ischaemia/reperfusion injury

1. Complement activation is implicated in the pathogenesis of intestinal ischaemia-reperfusion injury (I/R), although the relative importance of individual complement components is unclear. A C3a receptor antagonist N(2)-[(2,2-diphenylethoxy)acetyl]-l-arginine (C3aRA) has been compared with a C5a receptor antagonist (C5aRA), AcF-[OPdChaWR], in a rat model of intestinal I/R. 2. C3aRA (IC(50)=0.15 microm) and C5aRA (IC(50)=0.32 microm) bound selectively to human polymorphonuclear leukocyte (PMN) C3a and C5a receptors, respectively. Effects on circulating neutrophils and blood pressure in the rat were also assessed. 3. Anaesthetised rats, subjected to intestinal ischaemia (30 min) and reperfusion (120 min), were administered intravenously with either (A) the C3aRA (0.1-1.0 mg x kg(-1)); the C5aRA (1.0 mg x kg(-1)); the C3aRA+C5aRA (each 1.0 mg x kg(-1)); or vehicle, 45 min prior, or (B) the C3aRA (1.0 mg x kg(-1)) or vehicle, 120 min prior to reperfusion. 4. The C3aRA and C5aRA, administered 45 min prior to reperfusion, displayed similar efficacies at ameliorating several disease markers (increased oedema, elevated ALT levels and mucosal damage) of rat intestinal I/R. The combination drug treatment did not result in greater injury reduction than either antagonist alone. However, doses of the C3aRA (0.01-10 mg x kg(-1)) caused transient neutropaenia, and the highest dose (10 mg x kg(-1)) also caused a rapid and transient hypertension. 5. The C3aRA (1.0 mg x kg(-1)), delivered 120 min prior to reperfusion to remove the global effect of C3aRA-induced neutrophil sequestration, did not attenuate the markers of intestinal I/R, despite persistent C3aR antagonism at this time. 6. C3aR antagonism does not appear to be responsible for the anti-inflammatory actions of this C3aRA in intestinal I/R in the rat. Instead, C3aRA-mediated global neutrophil tissue sequestration during ischaemia and early reperfusion may account for the protective effects observed.

Differentiation of human hepatoma cells during confluence as revealed by gene expression profiling

Certain human hepatocarcinoma cells undergo differentiation when grown at confluence. In order to understand the basis for this differentiation, we investigated the phenotypic changes occurring during confluent growth of the human hepatoma B16A2 cell line. The global gene expression profile of B16A2 cells grown during confluence for 5 weeks was investigated using microarrays containing complementary sequences corresponding to approximately 10,000 genes, and compared with profiles of adult human liver and HepG2 cells. The major part of gene products detected were shared by all three systems and the hepatoma cell lines expressed surprisingly high levels of liver-enriched transcription factors. During confluence of B16A2 cells, the majority of transcriptional changes monitored were directed towards the phenotype of adult human liver in vivo, although the changes accounted for less than 10% of those necessary to acquire a native hepatic phenotype. Several markers of liver differentiation and regeneration were changed in similar manner as observed in developing liver and during liver regeneration. In conclusion, the data indicate that differentiation in vitro of the B16A2 cell line during confluence partially resembles that of hepatic differentiation and regeneration in vivo, implying a partial normalization of a low differentiated phenotype.

First dose of potential new medicines to humans: how animals help

The need for careful testing of new drugs in animal models before study in humans has been recognised by physicians since the First World War. Now, first human studies on new drugs are subject to detailed government guidelines, which in the European Union are presently being reinforced through the wide-ranging Clinical Trials Directive. However, despite their long history and widespread application, these guidelines are empirical and have been formulated with a paucity of critical scientific evidence. Here, we review the principles and the available, albeit limited, evidence that support the design and conduct of preclinical studies in a way that permits effective and safe first-dose studies of potential new medicines in humans.

Endothelial cells require STAT3 for protection against endotoxin-induced inflammation

Endothelial cells (ECs) are believed to be an important component in the protection from lipopolysaccharide (LPS)-induced endotoxic shock. However, the cellular and molecular mechanism is not well defined. Here, we report that signal transducer and activator of transcription (STAT) 3 is an essential regulator of the antiinflammatory function of ECs in systemic immunity. Because STAT3 deficiency results in early embryonic lethality, we have generated mice with a conditional STAT3 deletion in endothelium (STAT3^E−/−). STAT3^E−/− mice are healthy and fertile, and isolated ECs initiate normal tube formation in vitro. Conditional endothelial but not organ-specific (i.e., hepatocyte or cardiomyocyte) STAT3 knockout mice show an increased susceptibility to lethality after LPS challenge. The LPS response in STAT3^E−/− mice shows exaggerated inflammation and leukocyte infiltration in multiple organs combined with elevated activity of serum alanine aminotransferase and aspartate aminotransferase, indicating organ damage. Concomitantly, proinflammatory cytokines are produced at an exaggerated level and for a prolonged period. This defect cannot be explained by lack of antiinflammatory cytokines, such as interleukin 10 and transforming growth factor β. Instead, we have shown that a soluble activity derived from endothelia and dependent on STAT3 is critical for suppression of interferon γ. These data define STAT3 signaling within endothelia as a critical antiinflammatory mediator and provide new insight to the protective function of ECs in inflammation.

Evaluation of the cohort size in phase I dose escalation trials based on laboratory data

A survey of Phase I dose escalation trials published since 1995 shows that there is great disparity in all aspects of the design of the studies, and the cohort sizes range from 2 to 16 subjects with a great variety in the distribution between active and placebo-treated subjects. This study investigates the impact of the cohort size on Type I error and power in Phase I dose escalation trials based on laboratory data, with the hospitalization-induced increase in hepatic enzyme levels taken into consideration. The power of a Phase I dose escalation trial is very low, and only events with a very high probability of occurrence are detectable with acceptable power. For studies with cohort sizes smaller than 6 active subjects, there is much to gain with the inclusion of 1 extra subject, but for more than 10 subjects, little is gained by increasing the cohort size. With increasing cohort sizes, the probability of spontaneous non-drug-related events also increases, and this background rate needs to be considered when evaluating the trial.

Drug-induced liver disease

The incidence of drug-induced liver disease appears to be increasing, reflecting the increasing number of new agents that have been introduced into clinical use over the past several decades. Among the topics covered, the author discusses incidence, diagnosis, risk factors, clinical presentations, hepatitis, and vascular injury. The author also reviews the hepatic injury seen with commonly prescribed drugs, emphasizing newer developments in the field and recent publications and reports.

Enzyme induction and inhibition by new antiepileptic drugs: a review of human studies

The aim of this paper is to review a number of new antiepileptic agents (i.e. felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide) for their inducing and/or inhibitory properties in humans, mainly considering the interactions where they are involved as the cause rather than the object of such interactions. Two aspects have been particularly taken into account: the changes or absence of changes in plasma/serum concentrations of concomitant drugs and the direct or indirect evidence of induction, inhibition or lack of effect on the six major human hepatic CYP isozymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4), as well as on other CYP isozymes or enzyme systems. Felbamate clearly affects the pharmacokinetics of a number of drugs, generally increasing but also decreasing their concentrations. It induces enzymes such as CYP3A4 and inhibits enzymes such as CYP2C19 and those of the beta-oxidation pathway. Topiramate is not devoid of potential interaction properties: it decreases the plasma concentrations of ethinylestradiol, induces CYP3A4 and inhibits CYP2C19. For oxcarbazepine, no inhibitory, only inductive effects have been observed thus far. Felbamate. topiramate and oxcarbazepine may induce the metabolism of steroidal oral contraceptives. In this respect, tiagabine has been studied at a rather low dose. Pharmacodynamic or pharmacokinetic interaction seems to exist between lamotrigine and carbamazepine. Lamotrigine appears to be a weak inducer of UGTs, whereas induction of CYP3A4 seems improbable as the compound does not change the concentrations of oral contraceptives or the urinary excretion of 6beta-hydroxycortisol. Zonisamide has very peculiar pharmacokinetics and an extensive metabolism. Additional information on its enzyme inducing or inhibiting properties would be necessary, as data so far collected on its effect on the pharmacokinetics of other drugs are conflicting. Gabapentin, vigabatrin and in particular levetiracetam appear to be devoid of significant enzyme inducing or inhibiting properties.