The influence of chronic lobular hepatitis on pharmacokinetics of cefoperazone--a novel galactose single-point method as a measure of residual liver function

Long-term and short-term effects of hemodialysis on liver function evaluated using the galactose single-point test

Aim. The galactose single-point (GSP) test assesses functioning liver mass by measuring the galactose concentration in the blood 1 hour after its administration. The purpose of this study was to investigate the impact of hemodialysis (HD) on short-term and long-term liver function by use of GSP test. Methods. Seventy-four patients on maintenance HD (46 males and 28 females, 60.38 ± 11.86 years) with a mean time on HD of 60.77 ± 48.31 months were studied. The GSP values were compared in two groups: (1) before and after single session HD, and (2) after one year of maintenance HD. Results. Among the 74 HD patient, only the post-HD Cr levels and years on dialysis were significantly correlated with GSP values (r = 0.280, P < 0.05 and r = −0.240, P < 0.05, resp.). 14 of 74 patients were selected for GSP evaluation before and after a single HD session, and the hepatic clearance of galactose was similar (pre-HD 410 ± 254 g/mL, post-HD 439 ± 298 g/mL, P = 0.49). GSP values decreased from 420.20 ± 175.26 g/mL to 383.40 ± 153.97 g/mL after 1 year maintenance HD in other 15 patients (mean difference: 19.00 ± 37.66 g/mL, P < 0.05). Conclusions. Patients on maintenance HD for several years may experience improvement of their liver function. However, a single HD session does not affect liver function significantly as assessed by the GSP test. Since the metabolism of galactose is dependent on liver blood flow and hepatic functional mass, further studies are needed.

Protective effects of kaempferol on isoniazid- and rifampicin-induced hepatotoxicity

Isoniazid (INH) and rifampicin (RIF) are the first-line drugs for antituberculosis (anti-TB) chemotherapy. The levels of serum transaminases [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] are abnormal in 27% of patients undergoing INH and RIF treatments and in 19% of patients undergoing treatment with INH alone. Cytochrome P450 2E1 (CYP2E1) metabolizes many toxic substrates, including ethanol, carbon tetrachloride, and INH, which ultimately results in liver injury. The objective of this study was to screen for CYP2E1 inhibitors in vitro and investigate whether the selected compound could prevent INH/RIF-induced hepatotoxicity in vivo. We screened 83 known compounds from food and herbal medicines as inhibitors of CYP2E1. The hepatotoxic dose of INH/RIF was 50/100 mg kg(-1) day(-1). Hepatotoxicity was assessed using galactose single-point (GSP) method (a quantitative measurement of liver function), histopathological examination of the liver, malondialdehyde (MDA) assay, and measurement of AST and ALT activities. Kaempferol inhibited CYP2E1 activity in mice by 0.31- to 0.48-fold (p < 0.005). Mice with INH/RIF-induced hepatotoxicity showed significantly abnormal serum levels of AST and ALT, and GSP value, and these values could be decreased by the administration of kaempferol (p < 0.005). Kaempferol significantly reduced the depletion of hepatic glutathione and prevented the increase in MDA formation in mice. Furthermore, kaempferol did not affect the anti-TB effects of INH/RIF. To our knowledge, this is the first report of kaempferol's utility as an adjuvant for preventing CYP2E1-mediated hepatotoxicity induced by drugs such as INH and RIF.

A new approach to facilitate diagnosis of nonalcoholic fatty liver disease through a galactose single point method in rats with fatty liver

BACKGROUND

Liver biopsy reliably diagnoses nonalcoholic fatty liver disease, but its invasiveness and inter- and intra-observer errors limit its usefulness in monitoring.

AIMS

Use a galactose single point method or combined biochemical parameters to improve assessments of nonalcoholic fatty liver disease in a rat model.

METHODS

Three nonalcoholic fatty liver disease severities were generated in 50 rats: a control group (n=18) on a standard diet, and 2 study groups on a choline-deficient diet (n=18), with and without treatment with silymarin (n=14). At weeks 4, 8, and 18, a galactose solution (0.5 g/kg/body weight) was rapidly injected intravenously. Sixty minutes later, internal artery blood was taken for biochemical analyses, including galactose. The livers were then removed for haematoxylin-eosin staining and to measure the hepatic lipid content.

RESULTS

Alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, albumin, and total protein were each significantly correlated with nonalcoholic fatty liver disease severity. Regarding logistic regression, galactose single point method and total protein were significantly predictive. The optimal alanine aminotransferase cutoff point for nonalcoholic fatty liver disease prediction from the receiver-operating characteristic curve had 72.4% sensitivity and 52.4% specificity; galactose single point method alone had 82.8% and 72.4%, whereas galactose single point method+total protein showed 82.8% and 81.0%.

CONCLUSIONS

Both galactose single point method and galactose single point method+total protein had greater diagnostic sensitivity and specificity for nonalcoholic fatty liver disease than traditional biochemical tests.

A novel mechanism underlies the hepatotoxicity of pyrazinamide

Relatively little is known about the hepatotoxicity of pyrazinamide (PZA). PZA requires activation by amidase to form pyrazinoic acid (PA). Xanthine oxidase then hydroxylates PA to form 5-hydroxypyrazinoic acid (5-OH-PA). PZA can also be directly oxidized to form 5-OH-PZA. Before this study, it was unclear which metabolic pathway or PZA metabolites led to hepatotoxicity. This study determines whether PZA metabolites are responsible for PZA-induced hepatotoxicity. PZA metabolites were identified and cytotoxicity in HepG2 cells was assessed. Potential PZA and PA hepatotoxicity was then tested in rats. Urine specimens were collected from 153 tuberculosis (TB) patients, and the results were evaluated to confirm whether a correlation existed between PZA metabolite concentrations and hepatotoxicity. This led to the hypothesis that coadministration of amidase inhibitor (bis-p-nitrophenyl phosphate [BNPP]) decreases or prevents PZA- and PZA metabolite-induced hepatotoxicity in rats. PA and 5-OH-PA are more toxic than PZA. Electron microscopy showed that PZA and PA treatment of rats significantly increases aspartate transaminase (AST) and alanine aminotransferase (ALT) activity and galactose single-point (GSP) levels (P < 0.005). PA and 5-OH-PA levels are also significantly correlated with hepatotoxicity in the urine of TB patients (P < 0.005). Amidase inhibitor, BNPP, decreases PZA-induced, but not PA-induced, hepatotoxicity. This is the first report of a cell line, animal, and clinical trial confirming that the metabolite 5-OH-PA is responsible for PZA-induced hepatotoxicity.

Quantitative rat liver function test by galactose single point method

Summary

The purpose of this study was to investigate the galactose single point (GSP) method, a residual liver function test recently recommended by the US Food and Drug Administration, which can be a useful tool for rat liver function measurement. Rats were treated either with carbon tetrachloride (CCl4) alone (1 mL/kg, intraperitoneally [i.p.]) for one day or with isoniazid (INH) alone (150 mg/kg, i.p.) or (in order to ameliorate the effects of INH) with a combination of INH and bis- p-nitrophenyl phosphate (BNPP) (25 mg/kg, i.p.) for 21 days. Hepatotoxicity was assayed by plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and scores of histological activity index-necroinflammation (HAI-NI) of the respective liver specimens. The GSP method in rats was defined by the galactose blood level after 60 min. Significant differences in GSP values were observed between controls and the CCl4-treated rats. After 21 days of treatment, no significant changes in AST and ALT values were observed among the control, INH and INH-BNPP groups. There were significant differences in average GSP values for controls ( P < 0.001) and INH-BNPP ( P < 0.001) compared with INH alone. Highly significant correlations ( P < 0.001) were obtained between GSP and scores of HAI-NI for all the groups. GSP was concluded to be a more sensitive biomarker of INH-induced hepatotoxicity than AST or ALT in the rats. The GSP method has been proved to be a simple and useful tool for the quantitative determination of liver function in rats, which can possibly be extended to other animals.

Effects of hyperglycemia on quantitative liver functions by the galactose load test in diabetic rats

Blood galactose clearance after an intravenous galactose load has been widely used as a quantitative liver function test. We have developed a novel quantitative rat liver function test, the galactose single point (GSP) method, to assess residual liver function with various injuries by measuring single time point galactose concentration in blood after an intravenous bolus injection of galactose. The goal of this study was to evaluate the influence of nonhepatic factors such as hyperglycemia on GSP and galactose elimination capacity (GEC) in rats. Four groups of animal studies were carried out, as follows: (1) normal control (NC), (2) streptozotocin-induced diabetes (DM), (3) carbon tetrachloride-induced hepatotoxicity (CCl(4)), and (4) streptozotocin-induced diabetes with CCl(4)-induced hepatotoxicity (DM + CCl(4)). The serum glucose levels in the diabetic groups (DM and DM + CCl(4)) were significantly increased compared with the NC and CCl(4) groups (P < .001). A significant increase in hepatic activities of aspartate aminotransferase and alanine aminotransferase was observed in the CCl(4)-treated groups (CCl(4) and DM + CCl(4)) compared with the NC and DM groups (P < .001). In comparison with the NC group, the values of GSP and GEC in the diabetic groups (DM and DM + CCl(4)) were significantly reduced (P < .001) and increased (P < .01), respectively. Galactose single point had highly significant correlations with GEC (P < .001). These results suggest that galactose metabolism tests-as quantitative parameters of liver function-should be interpreted with caution in the condition of a significant hyperglycemia.