Liver factors involved in drug metabolism in experimentally infected rats: deleterious effect of ornithine alpha-ketoisocaproate.

This study was designed to determine the effect of ornithine alpha-ketoisocaproate (O-KIC), a compound reducing muscle protein breakdown in physiological conditions, on liver factors involved in drug metabolism in rats with acute retrograde pyelonephritis. 91 rats were assigned to 7 groups differing in the level of food intake, induced infection, and the treatment by O-KIC (168 mg/kg bw/day). Rats were killed on the third day. O-KIC increased nitrogen balance and weight gain in controls, but not in malnourished infected or non-infected rats. Liver glutathione was significantly reduced by O-KIC in malnourished infected and non-infected rats. Though O-KIC induced a rise in liver microsomal proteins in control and infected animals, it decreased cytochrome P-450 in controls, and aminopyrine demethylase in both control and infected groups.

Liver glutathione and cytochrome P450 activity in experimental infection: study of the relative effects of infectious stress and malnutrition.

OBJECTIVE: To study the effects of infection and malnutrition on liver glutathione and cytochrome P450 (P450) in rats. DESIGN: Controlled experimental groups (12 groups). ANIMALS: Adult male Sprague-Dawley rats. INTERVENTIONS: Experimental endocarditis, pyelonephritis, or peritonitis were caused. Controls included free-fed rats and sham-operated rats, pair-fed to infected animals. Infection was verified by tissue culture. Rats were killed 3 days (acute infection) or 10 days (chronic infection, except endocarditis) after the induction of infection. RESULTS: Sham rats had lower liver weights, liver/body weight, and liver glutathione values than controls. Infected rats had larger liver weights and liver/body weight ratios and liver glutathione content than shams, and larger liver/body weight ratios than controls (acute infection). Infected rats had lower P450 values than both shams and controls. CONCLUSION: The malnutrition associated with infection caused decreased liver weight and glutathione content. Infection increased the liver weight, and liver glutathione content, but caused severe reduction in liver P450. If the same finding is true in infected patients, it could have consequences for the management of such patients.

Effects of ketoacids on liver glutathione and microsomal enzymes in malnourished rats.

The progression of chronic renal failure is delayed by the use of low protein diets, but such diets are deficient in essential amino acids. In order to maintain good nutritional status, branched-chain ketoacids (BCKA) can be added to these diets. The effects of BCKA on protein metabolism in skeletal muscle is well established, but there is little information about their effects on liver metabolism. Protein deprivation affects some aspects of liver function such as drug metabolism (glutathione, cytochrome P-450 and enzymes). In a chronic protein malnutrition model, we have tested the efficacy of BCKA to correct these abnormalities when they are added to a low protein diet. RNA/DNA, liver proteins, microsomal proteins and glutathione were markedly improved; cytochrome P-450 was only partly improved, and aminopyrine demethylase was not affected. In conclusion, this study suggests that BCKA have a beneficial effect and may prevent the deterioration in the nutritional state of the liver in uremic patients.

Rehabilitation of microsomal enzymes in malnourished rats: comparison of parenteral versus oral refeeding.

Protein malnutrition decreases the activity of drug-metabolizing liver microsomal enzymes. In the first part of our study, we evaluated those enzymes during malnutrition and refeeding. Then we compared the effects of different nutritional patterns on these parameters. During malnutrition (M), rats were fed a 5% casein diet. During refeeding, they were randomized in 3 groups: oral refeeding (20% casein diet: A), continuous total parenteral nutrition (TPN: B) and oral energy refeeding (glucose + lipids) + continuous amino-acid infusion (C). Rats were sacrificed before and at various times during malnutrition and refeeding (2 to 28 days). There was no difference in caloric intake between the 3 groups. Nitrogen balance was not different in A and B. It was lower in C, though nitrogen intake was not different. Body and liver weights were not different between the 3 groups. Microsomal proteins and cytochrome P-450 were improved in A and B but not in C compared to M. Our results suggest that TPN (but not continuous amino-acids infusion + oral energy intake) is as effective as oral nutrition on rehabilitation of microsomal enzymes in malnourished rats.

Genetically determined oxidation polymorphism and drug hepatotoxicity. Study of 51 patients.

The influence of genetically determined oxidation polymorphism on drug hepatotoxicity has been poorly investigated and results are controversial. We studied drug oxidation capacity in 51 patients with hepatitis caused mainly by drugs undergoing oxidative metabolism, using dextromethorphan, a test compound recently proposed as a substitute for debrisoquine. Phenotyping was performed using the metabolic ratio (MR) calculated as MR = 0-10 h urinary output of dextromethorphan/0-10 h urinary output of dextrorphan (the main oxidative metabolite), after oral administration of 40 mg dextromethorphan hydrobromide. Dextromethorphan oxidation capacity was similar in patients and in 103 control subjects as judged by: (a) the prevalence of each phenotype (5.9% versus 3.9% for the poor metabolizer phenotype and 94.1% versus 96.1% for the extensive metabolizer phenotype; (b) the frequency distribution histograms of log metabolic ratio; (c) the mean values of dextromethorphan and dextrorphan urinary outputs and of log metabolic ratio for each phenotype. These results show that hepatotoxicity of several drugs, including amineptine, amodiaquine and Plethoryl, is related neither to an impairment in dextromethorphan oxidation capacity nor to an unusually high capacity to oxidize this drug.

The hepatotoxicity of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) in rats. Ultrastructural evidence of a delayed microtubular toxicity.

A few cases of liver involvement have been reported in patients receiving treatment with the antineoplastic nitrosourea CCNU. A single oral dose of 20 or 50 mg/kg CCNU in female Wistar rats induced an important increase in transaminases between day 2 and day 6, followed by a second, moderate increase between day 21 and day 28. Alkaline phosphatases and conjugated hyperbilirubinemia (threefold-increase) were noted for the two doses and were greater for the highest dose. Histological and ultrastructural studies disclosed hepatic lesions of two types: during the first phase of transaminase increase, inflammation of the portal tracts; during the second phase marked dilation of bile canaliculi and numerous filamentous bundles distributed at random throughout the liver cell cytoplasm like normal microtubules. Thus, CCNU induced pericholangitis and intrahepatic cholestasis with microtubular abnormalities. The long-term evolution of hepatic alterations revealed that in the 3rd month after a single oral dose of 20 mg/kg CCNU, lesions were persistent but stable; no reversibility was observed in the 3rd month after 50 mg/kg CCNU, and evolution towards cholangiolysis and biliary cirrhosis was noted. We suggest that CCNU causes a bimodal hepatotoxicity in rats: an early and prolonged ductal injury and a delayed anti-liver cell microtubule toxicity.

Inactivation of cytochrome P-450 by the drug methoxsalen.

Administration of methoxsalen (50 mumol X kg-1 i.p.) increased 4-fold the hexobarbital sleeping time in rats; at this low dose, SKF 525-A, piperonyl butoxide and cimetidine had little or no effect. In vitro, the concentration of methoxsalen inhibiting by 50% monooxygenase activities ranged from 10 microM (for benzo(a)-pyrene and hexobarbital hydroxylases] to 25 microM for 7-ethoxy-coumarin deethylase and aminopyrine demethylase); these values were in the range of those observed with SKF 525-A (1-50 microM) or piperonyl butoxide (10-100 microM) but much lower than those for cimetidine (100-500 microM). Methoxsalen (25-1000 microM) decreased cytochrome P-450 in vitro, in the presence of EDTA; this effect required NADPH and oxygen, was decreased by piperonyl butoxide and was increased by phenobarbital pretreatment. Similarly, administration of methoxsalen (125 mumol X kg-1 i.p.) decreased cytochrome P-450 and monooxygenase activities in vivo; the decrease in cytochrome P-450 was enhanced by phenobarbital pretreatment and was prevented by piperonyl butoxide. There was no evidence for lipid peroxidation, denaturation into cytochrome P-420, formation of cytochrome P-450-metabolite complexes, destruction of heme or formation of green pigments. In contrast, a reactive metabolite of methoxsalen covalently bound to microsomal proteins; covalent binding required NADPH and oxygen, was decreased by piperonyl butoxide and was increased by phenobarbital pretreatment. We conclude that methoxsalen is activated into a metabolite which destroys cytochrome P-450.

[Hepatitis due to pirprofen; 3 cases, 1 fatality]. / Hépatite au pirprofène; 3 cas dont 1 mortel.

We report three cases of jaundice in women taking 800 mg pirprofen.day-1 during 6 weeks to 4 months and a half. Two of them presented cutaneous side effects: one case was rapidly better with corticosteroids. Fatal case possibility incite to transaminase surveillance.

Hepatic antipyrine metabolism in malnourished patients: influence of the type of malnutrition and course after nutritional rehabilitation.

The present study of hepatic mixed function oxidase activity was carried out by determining antipyrine clearance in 49 patients presenting with energy malnutrition (group E, n = 26) or global protein-calorie malnutrition (group P, n = 23). A control group (group C, n = 25) was composed of subjects with good nutritional status. The metabolic clearance rate and weight-corrected clearance in group P were significantly lower than those in groups E and C. The weight clearances in the latter two groups were not significantly different, suggesting that mixed function oxidase activity decreases only in protein-calorie malnutrition. Antipyrine clearance was studied again in 27 patients after nutritional rehabilitation with artificial nutrition for 31 +/- 4 days (means +/- SEM). Concomitant with an improvement in nutritional state, clearances tended towards normal values in group P (n = 17) and were not significantly modified in group E (n = 10). It is thus important to take the type of malnutrition into account in pharmacological studies of malnourished humans in order to correctly adapt therapeutic doses.

[Postoperative gastrointestinal transit. Results of the measurement of segmental transit times]. / Transit gastrointestinal post-opératoire. Résultats de la mesure des temps de transit segmentaires.

The postoperative transit times of radioopaque markers through the gastrointestinal tract where measured in 6 patients after gastric surgery, in 13 patients after cholecystectomy, in 10 patients after appendicectomy and in 7 other patients who underwent general anesthesia without laparotomy. After ingestion of 20 markers, overall and segmental transit times were calculated according to their distribution on serial plain films of the abdomen taken 6 and 24 h after the operation, and every 24 h thereafter until complete evacuation of the markers. Overall transit times of the 3 groups of patients with laparotomy (171, 130 and 113 h respectively) were greater than overall transit times of patients without laparotomy (25 h). Overall transit times of patients with gastric operations were greater than overall transit times of patients with cholecystectomy (p less than 0.05) or appendicectomy (p less than 0.01). The increase in overall transit time was mainly due to an increased gastric transit time in patients after gastric surgery and an increased transit time through the right colon in patients who underwent cholecystectomy and appendicectomy. Once markers began to be defecated, their disappearance rate was the same in the 4 groups of patients. These results show that an increased overall transit time may be the consequence either of an increased transit time through the stomach or through the right colon, depending on the type of operation. As well, when digestive propulsive activity returns, it is de novo normal.

Mechanism for isaxonine hepatitis. I. Metabolic activation by mouse and human cytochrome P-450.

The metabolism of isaxonine was first investigated in mice. Incubation, under air, of [2-14C] isaxonine (1 mM) with mouse liver microsomes and an NADPH-generating system resulted in the irreversible binding of a [14C] isaxonine metabolite to microsomal proteins; binding required active microsomes, NADPH and oxygen, it was inhibited by 4 mM piperonyl butoxide or by a CO-O2 (80:20) atmosphere. In the presence of various concentrations of isaxonine (0.125-2 mM), binding followed Michaelis-Menten kinetics; the Vmax was increased by both phenobarbital and 3-methylcholanthrene pretreatments. In vivo, 2.5 hr after the administration of [2-14C] isaxonine (4 mmol X kg-1 i.p.), a [14C] isaxonine material was irreversibly bound to mouse liver proteins; this binding was decreased by piperonyl butoxide and increased by phenobarbital or 3-methylcholanthrene pretreatments. Irreversible binding also occurred in the kidney. Unlike their effects in the liver, piperonyl butoxide and phenobarbital did not modify significantly in vitro metabolic activation by kidney microsomes and in vivo covalent binding to kidney proteins; pretreatment with 3-methylcholanthrene increased both in vitro and in vivo binding in the kidney. In a second series of experiments, in vitro metabolic activation was demonstrated with human liver microsomes; as in mice, covalent binding required NADPH and was markedly inhibited by piperonyl butoxide. We conclude that isaxonine is activated by mouse and human cytochromes P-450 into a reactive metabolite. In vivo covalent binding to mouse liver and kidney proteins appears to result mainly from the in situ binding of the metabolite formed in each organ.

Mechanism for isaxonine hepatitis. II. Protective role of glutathione and toxicological studies in mice.

Coincubation of 0.4 mM [3H]glutathione with 4 mM isaxonine , an NADPH-generating system, glutathione S-transferase and mouse liver microsomes, followed by thin-layer chromatography of the incubation mixture, resulted in the appearance of a 3H-labeled peak with characteristics consistent with a glutathione- isaxonine metabolite adduct: this peak was absent if either isaxonine or the NADPH-generating system was omitted and was decreased if the transferase was omitted. In vivo, the concentrations of hepatic glutathione and glutathione disulfide were markedly decreased 2.5 hr after administration of isaxonine (4 mmol X kg-1 i.p.); this depletion of glutathione was prevented essentially by pretreatment with piperonyl butoxide. In vitro, addition of 4 mM glutathione decreased markedly the amount of [14C] isaxonine metabolite that bound to microsomal proteins during incubation of 1 mM [2-14C] isaxonine with hepatic microsomes and an NADPH-generating system. In vivo, pretreatment with diethylmaleate decreased further hepatic glutathione concentration and markedly increased the amount of [14C] isaxonine metabolite covalently bound to hepatic proteins, 2.5 hr after administration of [2-14C] isaxonine (4 mmol X kg-1 i.p.). Administration of isaxonine (4 mmol X kg-1 i.p.) decreased hepatic cytochrome P-450 concentration, but failed to produce liver cell necrosis, even in mice pretreated with phenobarbital, 3-methylcholanthrene or diethylmaleate, despite high levels of in vivo covalent binding in pretreated animals. We conclude that the reactive metabolite of isaxonine may be conjugated with glutathione or may covalently bind to hepatic proteins. The metabolite, however, has limited hepatotoxic potential in mice.

Effects of oral methoxy-psoralen photochemotherapy (PUVA) on liver function and antipyrin kinetics.

Standard liver function tests and antipyrin kinetics were studied in 19 non-alcoholic patients before and after a four-week PUVA treatment with oral methoxy-psoralen. Whereas liver function remained normal in all subjects, antipyrin clearance was significantly reduced at the end of PUVA therapy. Although the mechanism of this pharmacological effect remains unclarified, these results suggest that there is considerable potential for interactions to occur with other drugs metabolized by the same hepatic pathways (cytochrome P 450) in patients undergoing PUVA therapy.

Hepatic alterations during total parenteral nutrition in patients with inflammatory bowel disease: a possible consequence of lithocholate toxicity.

In order to understand the mechanism of hepatic abnormalities appearing during total parenteral nutrition, biliary bile acid composition and liver function tests were examined serially in 15 patients undergoing total parenteral nutrition for inflammatory bowel disease. In all 12 patients who underwent duodenal intubation before initiation of total parenteral nutrition, lithocholic acid accounted for less than 1% of total biliary bile acids. After 11-22 days of total parenteral nutrition, lithocholic acid accounted for 7%-15% of biliary bile acids in 5 patients and less than 1% of biliary bile acids in 10 patients. In the 5 patients with elevated levels of biliary lithocholic acid, serum alkaline phosphatase and aminotransferase activities rose progressively at serial determinations, the increase being significant after 2 wk of total parenteral nutrition. These results suggest that lithocholic acid may be involved in the hepatic lesions observed in patients undergoing total parenteral nutrition.