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Humans↗
Biomedical subjects
G C Farrell
Publications and source records attributed to G C Farrell.
Molecular epidemiology of hepatitis C in Australia.
The aim of this study was to determine the distribution of hepatitis C virus (HCV) genotypes in Australian patients with hepatitis C and to identify factors associated with particular genotypes. Serum isolates of HCV-RNA were genotyped using a commercial oligonucleotide hybridization (line probe) assay. Relationships between demographic factors, mode of HCV transmission and HCV genotype were assessed by logistic regression analysis. Among 463 patients with hepatitis C, 425 tested positive for HCV-RNA and a single HCV genotype was identified in 420 cases. The patients' places of birth were Australia or New Zealand (62%), Asia (13%), Europe (12%), Mediterranean (6%), Middle East (6%) and other countries (< 1%). The most common genotypes were type 1 (52%) or type 3 (32%); type 2 (9.3%), type 4 (5.5%) and type 6 (1.7%) were less common. Patients with genotype 1b were older (48 +/- 13 years, P< 0.001) and patients with genotype 3 were younger than the remaining patients (37 +/- 11 years vs 42 +/- 12 years, P< 0.001). Among type 1 isolates, 1b was more common for patients born outside Australia compared with those born in Australia (50% vs 13%, P< 0.001) whereas non-1b subtypes were more common among Australian-born patients. Likewise, 21 of 23 (91%) patients with type 4 were from Egypt and six of seven (86%) with type 6 were from Vietnam. The relative importance of parenteral risk factors for HCV also varied according to geographic origin. Thus, a definite risk factor for HCV acquisition was identified in > 95% of Australian-born patients, but in only 33% of Asian or Mediterranean-born patients. Logistic regression analysis indicated that region of birth and risk factor (intravenous drug use or not) would allow 98% of type 4 cases and 76% of type 1b cases to be identified correctly. In summary, region of birth, patterns of migration over time and risk factors for transmission of HCV interact to determine the distribution of HCV genotypes in a multi-racial community like Australia.
Adult↗
Separate and interactive regulation of cytochrome P450 3A4 by triiodothyronine, dexamethasone, and growth hormone in cultured hepatocytes.
CYP3A4, the predominant cytochrome P450 expressed in human liver, is responsible for the metabolism of endogenous steroids and many drugs. On the basis of pharmacokinetic studies in patients with hormonal derangements and the effects of replacement therapy, it has been suggested that iodothyronines decrease CYP3A4-mediated drug metabolism, whereas glucocorticoids and GH enhance CYP3A4 activity. The aim of the present study, using well differentiated human hepatocytes in primary culture, was to examine directly whether hormonal factors regulate CYP3A4 gene expression. Addition of T3 to primary hepatocytes resulted in a marked reduction of CYP3A4-catalyzed testosterone 6 beta-hydroxylase activity and corresponding levels of CYP3A4 protein and messenger ribonucleic acid compared to those in untreated cells. Conversely, both dexamethasone and GH treatment substantially increased CYP3A4 gene expression. None of the hormones studied consistently altered the expression of other human cytochrome P450 genes. We conclude that iodothyronines, glucocorticoids, and GH act directly on human hepatocytes to regulate the expression of CYP3A4, and these effects appear to be exerted at a pretranslational level. Altered regulation of hepatic CYP3A4 is, therefore, likely to account for previous observations concerning the effects of endocrine diseases and hormonal treatments on human cytochrome P450-mediated drug and steroid metabolism.
Cell Survival↗
Sonographic screening for hepatocellular carcinoma in patients with chronic hepatitis or cirrhosis: an evaluation.
OBJECTIVE: The purposes of this study were to determine the incidence of hepatocellular carcinoma (HCC) in patients with chronic hepatitis or cirrhosis and to assess the cost and benefit of sonographic screening for HCC. MATERIALS AND METHODS: We reviewed 647 sonograms of 232 patients obtained over an 8-year period. One hundred fifty-two patients had at least two sonograms. One hundred fifty-four men and 78 women with a mean age of 51 years were included. Most patients (n = 207) had biopsy-proven cirrhosis. Ethnicity, age, gender, type of liver disease, and alpha-fetoprotein levels were analyzed to determine factors associated with HCC detection. The costs of sonography and other tests were calculated using the Australian government Medicare benefits schedule. RESULTS: Thirty-one patients (13%) had elevated alpha-fetoprotein levels. Liver masses were found in 25 (11%) patients. Six (2.6%) patients had HCC on biopsy (n = 3) or other tests. All cases of HCC were inoperable because of tumor multicentricity or metastases (n = 2) or both, or because of the relatively large size or poor physical condition of the patient (n = 4) or both. The only variable associated with detection of HCC was alcohol-related liver disease (p = .01). Of the six patients with HCC, one had an elevated alpha-fetoprotein level. The yearly incidence of HCC was 1.4%. Other masses shown by sonography included regenerating nodules (n = 5), hemangiomas (n = 5), focal fat sparing (n = 4), metastases (n = 2), and other lesions (n = 3). No patient underwent surgical resection, which precluded calculation of a survival benefit. The cost of our screening program was $8472 (United States dollars) per HCC. CONCLUSION. Sonographic screening is superior to alpha-fetoprotein assay for detection of HCC, but in this study, screening did not decrease mortality.
Adult↗
Therapy of hepatitis C: interferon alfa-n1 trials.
Interferon alfa-n1 is produced from a lymphoid cell line and consists of multiple alpha interferon subtypes. Early studies indicated that interferon alfa-n1 was effective against hepatitis C, and a meta-analysis of published trials indicated that it was equally likely as recombinant alpha interferons to produce an end-of-treatment biochemical and histological response. However, there appeared to be a lower rate of posttreatment relapse after a 6-month course of interferon alfa-n1, so that the sustained response rate was 25% compared with 16% for recombinant alpha interferons. Subsequently, the efficacy of interferon alfa-n1 has been compared with recombinant alpha interferon directly in two large multicenter studies. The 096 International Hepatitis Comparative Study compared alfa-n1 with interferon alfa-2b in doses of 3 million units (MU) three times weekly for 24 weeks in a total of 1,071 patients. Biochemical end-of-treatment response rates were similar (35% for alfa-n1; 38% for alfa-2b), as were virological and histological responses. Relapse occurred more frequently after interferon alfa-2b, so that sustained biochemical (10.3% vs. 6.7%) and virological responses at 12 months were higher for alfa-n1. In a second study from Italy, interferon alfa-n1 was compared with interferon alfa-2a, using higher doses (6 MU three times weekly) until a biochemical response was obtained, and then using 3 MU three times weekly for a total of 12 months. The combined biochemical and virological sustained response rates were higher than reported with 6 months of treatment and were similar for alfa-n1 (17%) as for alfa-2a (16%). The superiority of 12 versus 6 months of treatment was also confirmed in the large multicenter 091 European Comparative Treatment Schedules study of 440 patients given four different regimens of therapy. Sustained biochemical response rates were 6% in patients who received 3 MU three times weekly for 6 months and 19% in those who received this dose for 12 months. When given for 12 months, there was no advantage to a slightly higher dose of interferon alfa-n1 (5 MU three times weekly). Thus, therapy with interferon alfa-n1 produces sustained response rates equivalent to the best obtained with recombinant alpha interferon. The optimal treatment regimen appears to be 3 MU given three times weekly for 12 months.
Antiviral Agents↗
Time-dependent expression of cytochrome P450 genes in primary cultures of well-differentiated human hepatocytes.
We sought to establish an in vitro system to study the regulation of highly differentiated hepatocellular functions, and specifically the time-dependent expression of four cytochrome P450 (P450) genes at the messenger RNA (mRNA) and protein levels. When seeded onto matrigel, hepatocytes could be maintained for 8 days in media that were free of serum and hormones (except for insulin). Cells retained a spherical phenotype; they secreted albumin and not alpha-fetoprotein; and the cellular RNA/DNA ratio rose progressively in culture. The isolation procedure and the duration of culture affected expression of specific P450s differently. CYP1A2, CYP2C9, and CYP2E1 mRNAs were not altered by cell isolation, and levels of CYP1A2 and CYP2C9 mRNA were also maintained for 8 days in culture, whereas CYP2E1 mRNA declined to 9% of values in fresh hepatocytes by day 8. CYP3A4 mRNA content was considerably decreased in freshly isolated hepatocytes compared with normal liver, and expression of this gene during the course of culture was more variable than that of the other P450s. Use of Williams' E medium considerably enhanced accumulation of CYP3A4 mRNA, compared with modified Waymouth 752/1 medium, but had a detrimental effect on levels of the other P450 mRNAs. Despite high levels of expression at the mRNA level, the microsomal protein contents of CYP1A2, CYP2C9, CYP2E1, and CYP3A4 declined progressively during the course of culture; this decline was most rapid for CYP3A4. These results confirm the potential of primary cultures of well-differentiated human hepatocytes for studies of P450 gene regulation in humans, but they also demonstrate that culture conditions are variables that must be carefully controlled when examining liver-specific gene expression in vitro. In particular, time in culture may variably affect expression of P450 enzyme changes at both the mRNA and protein levels.
Cell Differentiation↗
Ethanol perturbs receptor-operated cytosolic free calcium concentration signals in cultured rat hepatocytes.
BACKGROUND & AIMS: Studies of the acute effects of ethanol on hepatocellular free calcium concentration, [Ca2+]i, and on receptor-operated [Ca2+]i signals have produced conflicting results. The effects of ethanol on basal and receptor-operated [Ca2+]i signals in rat hepatocytes cultured on two different extracellular matrices were examined. METHODS: [Ca2+]i was determined by digitized fluorescence microscopy and inositol 1,4,5-trisphosphate (Ins[1,4,5]P3) by high-performance liquid chromatography (HPLC). RESULTS: Ethanol induced an increase in [Ca2+]i in hepatocytes cultured on collagen I but not on the more physiological substratum, matrigel. Compared with hepatocytes cultured on matrigel, cells on collagen I exerted less responsiveness and lower amplitude of [Ca2+]i signals to vasopressin or phenylephrine. The effects of ethanol on receptor-operated [Ca2+]i signals were examined in hepatocytes cultured on matrigel. Incubation of hepatocytes with physiologically attainable concentrations of ethanol (20-30 mmol/L) for 30 minutes to 48 hours perturbed epidermal growth factor, phenylephrine, and lower concentration (< or = 1 nmol/L) of vasopressin-induced [Ca2+]i signaling by reducing the amplitude and changing the pattern of [Ca2+]i signals. Alcohol induced-impairment of [Ca2+]i signaling was associated with decreased production of Ins(1,4,5)P3. CONCLUSIONS: Alcohol does not itself evoke an increase in [Ca2+]i in hepatocytes cultured on matrigel but perturbs receptor-operated [Ca2+]i signaling. This is associated with and could be caused by impaired generation of Ins(1,4,5)P3.
Adrenergic alpha-Agonists↗
Drug-induced hepatic injury.
Drugs and other chemical toxins account for less than 5% of cases of jaundice or acute hepatitis and fewer cases of chronic liver disease, but they are an important cause of more severe types of hepatic injury. Drug reactions produce an array of hepatic lesions that mimic all known hepatobiliary diseases; this poses a diagnostic challenge for physicians and pathologists. Diagnosis of drug-induced hepatic injury is circumstantial, with positive rechallenge being the only factor that unequivocally implicates a particular agent. Nonetheless, other aspects of the temporal relationship between drug ingestion and adverse reaction, exclusion of other diseases, the presence of extrahepatic features of drug hypersensitivity and some findings on liver biopsy can lend support to the diagnosis. Some of these issues will be explored in this review by considering contemporary paradigms of drug-induced hepatic injury. Factors that predispose to dose-dependent hepatic injury will be considered in relation to acetaminophen, an example of acute hepatotoxicity, and methotrexate, an agent that can produce hepatic fibrosis. Flucloxacillin will be discussed as an example of drug-induced cholestatic hepatitis often associated with prolonged cholestasis and the vanishing bile duct syndrome. Minocycline and diclofenac will be mentioned as two drugs for which drug hepatitis is an exceedingly rare complication. Finally, the evidence that Chinese herbal medicines can be hepatotoxic will be reviewed.
Anti-Bacterial Agents↗
Chronic ethanol administration to rats decreases receptor-operated mobilization of intracellular ionic calcium in cultured hepatocytes and inhibits 1,4,5-inositol trisphosphate production: relevance to impaired liver regeneration.
We tested the hypothesis that ethanol impairs liver regeneration by abrogating receptor-mediated elevation of cytosolic free calcium ([Ca2+]i). In rats fed for 16 weeks with ethanol, hepatocellular proliferation induced by partial hepatectomy was greatly impaired. Similarly, EGF-induced DNA synthesis was reduced in cultured hepatocytes from ethanol-fed rats. There was no change in the number or affinity of EGF receptors on hepatocytes from ethanol-fed rats. Despite this, EGF-mediated production of inositol 1,4,5-trisphosphate (Ins[1,4,5]P3) was lower in hepatocytes from ethanol-fed rats, and the EGF-induced [Ca2+]i transient appeared to be abrogated. When vasopressin or phenylephrine were used as cell surface receptor ligands, hepatocytes cultured from ethanol-fed rats exhibited major reductions in Ins(1,4,5)P3 synthesis. This was associated with greatly truncated [Ca2+]i transients. These changes were not due to an effect on the Ins(1,4,5)P3 receptor on the endoplasmic reticulum or to a decrease in the size of the Ins(1,4,5)P3-mobilizable intracellular Ca+2 store. Further, mobilization of the same Ca2+ store by 2,5-di-tert-butylhydroquinone or thapsigargin restored the ability of hepatocytes from ethanol-fed rats to proliferate when exposed to EGF. It is concluded that chronic ethanol consumption inhibits liver regeneration by a mechanism that is, at least partly, the result of impaired receptor-operated [Ca2+]i signaling due to reduced generation of Ins(1,4,5)P3.
Alcoholism↗
Effects of metyrapone on expression of CYPs 2C11, 3A2, and other 3A genes in rat hepatocytes cultured on matrigel.
Hepatocytes cultured on matrigel express many liver-specific functions, but the levels and activities of the predominant male-specific rat hepatic CYPs, 3A2 and 2C11, decline rapidly in culture. Metyrapone maintains the level of total cytochrome P450 of rat hepatocytes in primary culture, but the mechanism underlying this effect has not been completely elucidated. The present study sought to determine whether metyrapone acts solely to stabilise CYP proteins in rat hepatocytes cultured on matrigel, or whether it also influences mRNA levels of the encoding genes. Metyrapone maintained the level of total cytochrome P450 in cultured hepatocytes so that values were > 200% of those found in untreated control cells 24 hr after isolation. At this time, CYP3A2-mediated testosterone 6 beta-hydroxylation was approximately 7-fold higher in hepatocytes cultured in the presence of metyrapone than in control cells, and CYP2C11-dependent testosterone 2 alpha- and 16 alpha-hydroxylation activities were between 2 and 3-fold greater. The results inferred from catalytic activities were supported by immunoquantitation of CYP3A and 2C11 proteins. The trend of increased CYP protein levels in metyrapone-treated cells continued throughout the 48-hr culture period. In control cells, CYP3A2 and 2C11 mRNA levels fell abruptly in culture to reach values at 24 hr that were < 30% of those in freshly isolated cells; addition of metyrapone failed to arrest this fall. However, treatment of cells with metyrapone considerably elevated levels of one or more CYP3A subfamily mRNA species, as detected by a riboprobe based on the cDNA for CYP3A1 ("CYP3A1-like mRNA') that were demonstrated, by another riboprobe, not to be CYP3A2 or RNCYP3AM. RT-PCR of mRNA prepared from cultured hepatocytes, followed by restriction mapping of the cloned cDNAs was used to characterise the CYP3A induced by metyrapone. This revealed that elevated levels of the CYP3A1-like mRNA were attributable to induction of RL33/cDEX mRNA; there were no CYP3A1 cDNAs isolated from these cells. These data are interpreted as indicating that metyrapone stabilises the expression of cytochrome P450 in culture by both pre- and posttranslational mechanisms. The particular mechanism employed is gene-specific, whereby even the highly homologous genes CYP3A2, RL33/cDEX and, possibly, RNCYP3AM are subject to different types of regulation in the presence of metyrapone.
Animals↗
Impaired bile flow and disordered hepatic calcium homeostasis are early features of halothane-induced liver injury in guinea pigs.
To characterize the early events in liver injury produced by halothane, experiments were performed in genetically susceptible guinea pigs 19 hours after halothane exposure. Serum bile acid concentrations were fourfold increased in halothane-exposed animals compared with controls. In isolated perfused liver experiments, livers from halothane-exposed animals did not differ in hepatic oxygen uptake or in perfusion pressure at the end of experiments, but bile flow and biliary bile salt concentrations were reduced. Hepatic calcium content was increased in halothane-exposed guinea pigs compared with controls, and further experiments were performed to explore the reason for this. As determined by infusion of 45Ca to steady-state perfusate concentrations, hepatic calcium clearance was increased in halothane-exposed guinea pigs compared with controls (0.37 +/- 0.06 vs. 0.28 +/- 0.02 mL/min, P < .01). Decreased biliary excretion of calcium was also noted and was entirely attributable to reduced bile flow. However, although decreased excretion contributed to hepatic accumulation of calcium, it was quantitatively less important than enhanced hepatic uptake. As indicated by passage of a bolus of horseradish peroxidase from perfusate into bile, hepatic tight junction permeability was increased five-fold after halothane exposure. It is concluded that cholestasis, as exemplified by reduced bile flow, is an early feature of the liver injury produced by halothane in guinea pigs and is associated with increased tight junction permeability. Although the decrease in bile flow contributes to an early increase in hepatic calcium content, entry of calcium from the perfusion compartment is quantitatively more important.
Animals↗
Interferon gamma down-regulates cytochrome P450 3A genes in primary cultures of well-differentiated rat hepatocytes.
Administration of interferons of both the gamma and alfa/beta classes down-regulates hepatic cytochrome P450 (CYP) genes when administered to humans or rats. In male rats, interferons decrease expression of CYP3A2 at a pretranslational level, but because interferons also release other cytokines in vivo, it is unclear whether this is a direct effect on hepatocytes. We therefore examined the effects of rat recombinant interferon gamma (IFN-gamma) on CYP3A2, other 3A genes, and 2C11 in stable primary cultures of male rat hepatocytes. Hepatocytes were cultured on matrigel in Williams' E, and messenger RNAs (mRNAs) for 3A2, 3A1-like CYPs, and 2C11 mRNA were determined by RNase protection assays. CYP3A and 2C11 proteins were immunoquantified, and their catalytic activities were estimated by testosterone hydroxylation pathways. In control cells, 3A2 mRNA decreased initially but then recovered, and stable levels (15% of freshly isolated cells) were attained between days 3 and 7. Phenobarbital increased 3A2 mRNA to 60-120% values of freshly isolated cells, and mRNA for 3A1-like CYPs were increased 20-fold. In both control and phenobarbital-treated hepatocytes, rat recombinant IFN-gamma (33 U/mL) reduced mRNA for 3A2 and 3A1-like CYPs, as well as 3A protein and testosterone 6 beta-hydroxylase activity. Interferon had no effect on CYP2C11 at mRNA or protein levels in untreated cells, although a reduction in 2C11 protein was evident in phenobarbital-treated cultures. It is concluded that interferon directly alters expression of constitutive and inducible CYP3A genes in well-differentiated male rat hepatocytes in culture, but has no effect on constitutive expression of CYP2C11.
Animals↗
The central role of sinusoidal endothelial cells in hepatic hypoxia-reoxygenation injury in the rat.
The role of individual cell types in hepatic hypoxia-reoxygenation (reperfusion) injury has not been completely defined. We therefore examined the effects of hypoxia and hypoxia-reoxygenation on the viability of rat hepatocytes, Kupffer cells, and sinusoidal endothelial cells (SECs) in primary culture and whether direct exposure to hypoxia followed by reoxygenation activated Kupffer cells. Cultures of hepatocytes (purity > 99%), Kupffer cells (97%), and endothelial cells (> 93%) were established as single-cell types and as cocultures. Hypoxia was achieved by culturing cells under 95% N2/5% CO2, and cell viability was estimated by lactate dehydrogenase (LDH) leakage and Trypan blue exclusion. Kupffer cells and endothelial cells were more resistant to hypoxia than hepatocytes. Following 4-8 hours of hypoxia, reoxygenation accentuated cell death in endothelial cells. In contrast, reoxygenation did not accentuate cell death in hepatocytes or in resting Kupffer cells. The activation of Kupffer cells by the addition of lipopolysaccharide failed to alter their response to hypoxia-reoxygenation. The addition of phorbol myristate acetate to Kupffer cells stimulated the production of superoxide as expected, and the medium from these activated cells augmented the cellular injury of hypoxic hepatocytes. In contrast, hypoxia-reoxygenation did not stimulate Kupffer cells to produce superoxide or other hepatotoxic products. Moreover, Kupffer cells in coculture with hepatocytes did not augment hepatocyte injury after hypoxia-reoxygenation. Likewise, in cocultures of Kupffer cells and SECs, the presence of the Kupffer cell failed to enhance endothelial injury following hypoxia-reoxygenation, and these cocultures did not produce superoxide after reoxygenation. Thus, despite other evidence that Kupffer cells are activated in the intact liver during reperfusion injury, when present in isolation, only endothelial cells possess the innate capacity to undergo hypoxia-reoxygenation injury. Furthermore, changes in oxygen tension alone are not sufficient to activate Kupffer cells to secrete superoxides or other cell products that are toxic to hepatocytes or endothelial cells. It is concluded that SECs play a central role in hypoxia-reoxygenation injury, and the factors that activate Kupffer cells in vivo require further study.
Animals↗
Two years versus six months of interferon therapy for chronic hepatitis C.
Short-term (end-of-treatment) responses (ETR) to interferon (IFN) therapy for chronic hepatitis C are encouraging; however, the relapse rate is high, and long-term response is obtained in only 12-25% of patients. The Australian Hepatitis C Study Group conducted a trial of 230 patients that compared the standard 3 MU three times a week six-month course of IFN-alpha2b with 5 MU three times a week for six months (5 MU group) or 3 MU three times a week for two years (two-year group). ETR (normalization of serum aminotransferase level until the end of treatment) rates based on an intent-to-treat analysis were 64% for the 5 MU group and 58% for the combined 3 MU groups. After six months of treatment, the overall relapse rate was 71%, and the long-term response (LTR; continued normal aminotransferase until six month follow up) rate did not differ significantly between the 3 MU (17% of all treated, 27% ETR) and 5 MU groups (20% of all treated, 31% ETR). In contrast, among the 46 patients who exhibited an ETR in the two-year group, 27 (59%) had a LTR to IFN, resulting in an overall LTR rate of 33% for all patients treated for up to two years (P < 0.001 compared with 3 MU group). Among these 46 subjects, 11 did not complete the full two-year course, including eight who withdrew due to adverse effects. Nine of these 11 patients had received at least 12 months of therapy. All 18 LTR subjects tested (irrespective of treatment group) were serum HCV-RNA negative at the 12-month follow-up evaluation. Improvement in hepatic inflammation was significantly greater among those treated for two years compared with six months, but there was no reduction in fibrosis score in any group. Among the entire study group, treatment duration, liver histology, and liver function (assessed by antipyrine clearance test) were the only independent predictors of ETR, although HCV genotype was closely related to histological severity (eg, cirrhosis was present in 60% of type 1 and 18% of type 3). Viral load and duration of infection were additional predictors of LTR; however, there were insufficient data to determine whether prolonging treatment beyond six months overcomes the negative impact of these predictors. Continuing IFN therapy for at least 12 months decreases the relapse rate by 50% and thereby improves the LTR rate compared with a six-month treatment course. However, our experience of 24 months of treatment indicates that initial IFN treatment courses of this duration are not well tolerated by approximately 20% (8/46) of patients and are unlikely to improve the results obtained with 12-18 months of treatment.
Chronic Disease↗
Increased hepatocyte CYP2E1 expression in a rat nutritional model of hepatic steatosis with inflammation.
BACKGROUND & AIMS: Nonalcoholic steatohepatitis is morphologically identical to alcoholic hepatitis and has multiple etiologic associations and an unknown pathogenesis. The present study used a rat nutritional model of hepatic steatosis with inflammation to test the hypothesis that induction of the alcohol-inducible hepatic cytochrome P450 (CYP) 2E1 is associated with production of steatohepatitis. METHODS: Rats received a diet devoid of methionine-choline. CYP2E1 protein was detected in liver sections by immunohistochemistry and in hepatic microsomal fractions by immunoblotting; CYP2E1 activity was detected by N-demethylation of N,N-dimethylnltrosamine (NDMA). CYP2E1 messenger RNA was analyzed by Northern blotting and slot blot hybridization. RESULTS: After 4 weeks of methionine-choline devoid diet, macrovesicular steatosis and an inflammatory infiltrate were prominent in hepatic acinar zone 3. CYP2E1 immunostaining was increased and had a more extensive acinar distribution corresponding to that of the steatosis. Microsomal CYP2E1 protein, NDMA activity, and hepatic CYP2E1 messenger RNA levels were all correspondingly increased. CONCLUSIONS: CYP2E1 is induced, partly at a pretranslational level, in this experimental form of steatohepatitis. The finding of biochemical and histological similarities between this nutritional model of hepatic steatosis with inflammation and alcoholic hepatitis indicates possible clues to common pathogenetic mechanisms. The relevance of this finding to human nonalcoholic steatohepatitis remains uncertain and requires further investigation of human liver specimens.
Animals↗
Virus and host factors are both important determinants of response to interferon treatment among patients with chronic hepatitis C.
Virus and host factors have both been linked to the response to interferon treatment among patients with chronic hepatitis C but their relative importance and potential interactions are unclear. Hepatitis C virus genotype and level of viraemia were determined in pretreatment sera from 65 Australian patients treated with interferon-alpha 2b (IFN-alpha 2b), 3 MU tiw for 6 months. Hepatitis C viraemia was quantitated by a competitive reverse transcription-polymerase chain reaction (RT-PCR) method and genotype was determined by a line probe assay. By univariate analysis, there were positive associations between initial (short-term) responses to IFN treatment and younger age (P = 0.004), absence of cirrhosis (P = 0.01), and injecting drug use as risk factor for infection (P = 0.05) but not gender, duration of infection, or level of viraemia. Genotype appeared to be important (P = 0.06) but failed to reach statistical significance. By multivariate analysis, absence of cirrhosis was the only significant independent predictor of treatment response (P = 0.01). Among initial responders, the factors associated with long-term response were the pretreatment HCV RNA titre and the duration of infection. There was a close association between viral genotype, but not viral load, and the severity of liver disease. An interplay of factors determines the outcome of a 6-month course of interferon treatment for hepatitis C. Severity of liver disease, but not the viral load, is the most crucial determinant of initial response to interferon, and histological severity appeared to be influenced by the viral genotype. The level of hepatitis C virus (HCV) viraemia and the duration of infection are independent determinants of long-term response by affecting the relapse rate after interferon treatment.
Chronic Disease↗
Influence of clinicopathological variables on CYP protein expression in human liver.
Drug metabolism is usually impaired in malnourished patients with decompensated cirrhosis, but the separate influence of clinicopathological variables, including nutritional status, on the expression of hepatic cytochrome P450 proteins has not been well characterized. We determined the hepatic content of CYP1A2, CYP2C8/10, CYP2E1 and CYP3A proteins in 71 subjects, 21 with histologically normal livers and 50 with chronic liver disease, and then tested for potential relationships between patient variables and individual CYP proteins by multivariate linear regression analysis. Variables analysed included nutritional status (determined by experienced clinicians), serum albumin and bilirubin concentrations, prothrombin time, the grade of ascites and hepatic encephalopathy, and the Child-Pugh score. Impaired nutrition and cachexia were associated with reductions of CYP2C8/10 levels of approximately 19 and 39%, respectively, relative to cases in which nutrition was replete. Similarly, CYP2E1 protein was reduced by approximately 13 and 26%, according to the apparent severity of nutritional impairment. In contrast, nutritional status did not contribute to variability in expression of CYP1A2 or CYP3A proteins. Of the clinicopathological variables analysed, only serum bilirubin was shown to have an independent influence on CYP protein content. Thus, elevated serum bilirubin concentrations were associated with significant declines in the contents of CYP1A2 and CYP2C8/10 but not CYP3A or CYP2E1. The mechanisms for the effects of nutritional status and serum bilirubin concentration on the levels of CYP proteins are unclear, but could be mediated by factors such as cytokines, dietary composition and alterations in the level of serum bile acids. Knowledge of the influence of clinicopathological factors and nutritional status on CYP expression should lead to more rational drug prescribing in patients with hepatic disease.
Bilirubin↗
Sequential changes in serum levels of individual bile acids in patients with chronic cholestatic liver disease.
In order to determine the value of serum bile acids in predicting the course of chronic cholestatic liver diseases, we measured individual serum bile acids serially, using high-performance liquid chromatography, over a 4 year observation period in 12 patients with primary biliary cirrhosis and six patients with primary sclerosing cholangitis. The changes in individual serum bile acids and the ratios thereof, conventional liver tests and Child-Turcotte and Mayo scores were compared between survivors (n = 10) and patients who underwent liver transplantation for (n = 3) or died of the liver disease (n = 5). Patients with a serum total chenodeoxycholic acid concentration at study entry that exceded 15 mumol/L were 10 times more likely to die or need a liver transplant in the following 4 years than those with chenodeoxycholic acid levels < 15 mumol/L (P < 0.05). None of the other biochemical parameters or clinicopathological scores could similarly discriminate between the two groups at entry. Time-dependent analyses for the cholic acid/chenodeoxycholic acid ratio, serum total bilirubin and albumin concentrations and Child-Turcotte and Mayo scores were able to differentiate between primary sclerosing cholangitis patients who died or were transplanted and those who were not, whereas age of the patients and other parameters did not. The taurocholic acid/taurochenodeoxycholic acid ratio fell during progression of primary biliary cirrhosis but rose in temporal relationship with primary sclerosing cholangitis. This differential pattern of change was unique compared with other clinical and laboratory indices. In conclusion, serum chenodeoxycholic acid levels and the cholic acid/chenodeoxycholic acid ratio in both diseases were independent indices that allowed for the prediction of survival or the need for liver transplantation. These indices are worthy of further examination in a larger group of patients as prognostic criteria for chronic cholestatic liver disease and in the assessment of the efficacy of therapeutic interventions, including liver transplantations.
Adult↗