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Biomedical subjects

R Poupon

Publications and source records attributed to R Poupon.

At least 91 records · Page 5Linked to original sources
PubMed1995

Metabolism of ornithine, alpha-ketoglutarate and arginine in isolated perfused rat liver.

Ornithine (Orn; alpha-ketoglutarate (alpha KG) salt) and arginine (Arg) supplementation of enteral diets has been advocated in the treatment of hypercatabolism of trauma patients, but both compounds are subject to extensive hepatic metabolism. To compare the metabolism of these two compounds and to evaluate the possible influence of the alpha KG moiety, livers were perfused with alpha KG, Orn, ornithine alpha-ketoglutarate (OKG) or Arg (n 6 in each group) for 1 h. Arg uptake was nearly fourfold higher than Orn uptake (690 (SD 162) v. 178 (SD 30) nmol/min per g liver), and Orn uptake was not modified by alpha KG. Orn was totally metabolized by the liver, whereas Arg led to Orn release (408 (SD 159) nmol/min per g liver) and a threefold stimulation of urea production (Arg 1.44 (SD 0.22) v. Orn 0.45 (SD 0.09) mumol/min per g liver). alpha KG alone only increased hepatic aspartate uptake but, when associated with Orn as OKG, it led to an increase in glutamate release and in proline content in the liver and to a decrease in proline uptake. From these findings we conclude that (1) Arg load is extensively metabolized by the liver, inducing urea production, (2) in enteral use, Orn supplementation appears preferable to Arg as it is less ureogenic (as also recently demonstrated in vivo in stressed rats receiving isomolar amounts of Arg and Orn), (3) the liver participates in the Orn-alpha KG metabolic interaction, mostly in proline metabolism, which occurs in the splanchnic area.

Animals↗
PubMed1995

Absence of anti-LKM-1 antibody in hepatitis C viral infection in the United States of America.

Several studies from Europe have observed a relationship between hepatitis C virus infection and anti-liver/kidney microsome-1 (anti-LKM-1) positive chronic hepatitis. It has been suggested that hepatitis C may induce an autoimmune phenomenon that leads to the development of a specific type (type II anti-LKM-1 positive) autoimmune chronic hepatitis. We evaluated 204 sera from patients with well-documented hepatitis C infection from two centres in the United States of America and compared them with sera from 428 French patients from three centres. We evaluated the serological prevalence of anti-smooth muscle antibodies, anti-nuclear antibodies, anti-liver cytosol antibodies, and anti-mitochondrial antibodies subtype anti-M2 in patients with chronic hepatitis C. The two groups were matched in their ages, gender, mode of transmission of hepatitis C infection and severity of liver disease. Anti-LKM-1 was not observed in the patients from the USA at a time when it was noted in 3.7% of French patients. There were no differences, however, in the expression of other auto-antibodies, which were often in low titres. Absence of anti-LKM-1 in USA sera in comparison with French sera suggests that there may be differences in induction of anti-LKM-1 related to environmental and/or host genetic factors, and/or genomic variation in the hepatitis C virus.

Age Factors↗
PubMed1995

Metabolism of alpha-ketoisocaproic acid in isolated perfused liver of cirrhotic rats.

To determine the hepatic fate of alpha-ketoisocaproate (KIC) in cirrhosis, six groups of isolated rat livers were perfused with 0, 0.5, 1 (with or without alpha-[1-14C]KIC), 2, and 5 mM KIC; control livers from healthy rats were studied in parallel under similar conditions. KIC was rapidly removed by the normal livers, whereas uptake was lower in the cirrhotic livers at all concentrations tested (at 2 mM, 4.04 +/- 0.33 vs. 6.32 +/- 0.58 mumol/min; P < or = 0.05). The transamination pathway, evaluated by leucine exchanges, was more important in the cirrhotic livers (25.4 vs. 6.8% in controls at 2 mM). The incorporation of alpha-[1-14C]KIC in proteins of cirrhotic liver was increased compared with controls (0.25 +/- 0.04% of alpha-[1-14C]KIC was incorporated in proteins excreted in perfusate vs. 0.20 +/- 0.04 in controls; P < or = 0.05). In addition, a line of evidence suggests that glutamine rather than glutamate is the N donor for leucine synthesis from KIC. The decarboxylation pathway evaluated by beta-hydroxybutyrate production and by 14CO2 release from alpha-[1-14C]KIC was reduced, respectively, by 40-85% (according to KIC dose) and by 24% at 90 min in cirrhotic livers compared with healthy livers. These results indicate a dramatic modification of KIC metabolism in the cirrhotic liver; its uptake by the liver is decreased and its incorporation into proteins is increased via an enhancement of transamination to leucine, probably as a consequence of an inhibition of branched-chain keto acid dehydrogenase.

Animals↗
PubMed1995

Plasma alpha-glutathione S-transferase assessed as a marker of liver damage in patients with chronic hepatitis C.

alpha-Glutathione S-transferase (alpha-GST; EC 2.5.1.18) has been advocated as a better marker of hepatocellular damage than the transaminases in toxic and autoimmune hepatitis. We have assessed the potential interest of plasma alpha-GST determination in 94 anti-hepatitis C virus-positive patients with histologically proven chronic hepatitis C (34 women, 60 men, ages 40.0 +/- 11.9 years). Blood samples were assayed for aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase, alkaline phosphatase, and alpha-GST on the same day a liver biopsy was performed. alpha-GST concentrations were significantly above reference values in 64% of patients (compared with 58% for AST, 68% for ALT), and this increase was seen in 52% of patients with normal values for transaminases and a Knodell score > 3. Furthermore, there was a significant correlation between alpha-GST and lobular necrosis score (r = 0.31; P < 0.01). Our findings suggest that association of plasma alpha-GST with ALT may improve the biochemical assessment of liver damage in patients with chronic hepatitis C.

Adult↗
PubMed1995

[Chronic viral hepatitis C. Anatomoclinical and biological correlations].

OBJECTIVES: The relations between the severity of histopathological lesions and epidemiological, clinical and biological data were studied in 86 patients with chronic viral hepatitis C. PATIENTS AND METHODS: None of the patients had any clinical signs of decompensated liver disease. Three groups of patients were individualized according to histopathological findings: 17 (20%) had chronic persistent hepatitis, 48 (56%) had chronic active hepatitis without cirrhosis, and 21 (24%) had cirrhosis. RESULTS: Patients with cirrhosis differed significantly from patients in the two other groups for all biological parameters. With multivariate analysis, alkaline phosphatase activity and serum hyaluronic acid were two independent parameters significantly associated with cirrhosis. A serum hyaluronic acid level above 150 micrograms/L or alkaline phosphatase activity above normal were predictive of cirrhosis with a sensitivity of 87% and a specificity of 93%. None of the parameters in this study provided a clear distinction between patients with chronic persistent and chronic active hepatitis. CONCLUSION: Determination of serum hyaluronic acid and alkaline phosphatase activity as a non invasive index of cirrhosis could be useful for diagnosis and follow-up in patients with chronic viral hepatitis C.

Adult↗
PubMed1995

Effects of ursodeoxycholic acid and chenodeoxycholic acid on human hepatocytes in primary culture.

Hepatic bile acid concentrations are elevated in chronic cholestasis because of reduced canalicular excretion and active ileal absorption of the fraction eliminated in the gut. Ursodeoxycholic acid (UDCA) reduces the intestinal absorption of endogenous bile acids, thereby diminishing the concentrations to which liver cells are exposed. In the isolated perfused liver (in which vectorial bile acid transport is maintained), UDCA reduces the cytotoxic and cholestatic effects of endogenous bile acids. As a result, it has been suggested that UDCA or one of its conjugates could have a direct protective effect on hepatocyte structure and function. We therefore studied the effects of chenodeoxycholic acid (CDCA) and tauroursodeoxycholic acid (TUDCA) alone and in combination on the viability and certain functions of human hepatocytes in primary culture. TUDCA did not affect intracellular concentrations of CDCA when added concomitantly. In other experiments, CDCA (100 to 500 mumol/L) induced concentration-dependent increases in lactate dehydrogenase (LDH) leakage and decreases in cellular protein synthesis and albumin secretion. Neither TUDCA nor UDCA had similar effects at the same concentrations, nor did they have a protective effect when added concomitantly with CDCA at equimolar or twice-equimolar concentrations. These results suggest that UDCA has no direct cytoprotective effect when the bile acid concentrations to which human hepatocytes are exposed are unchanged. They also suggest that the hepatoprotective effect of UDCA in cholestatic human liver diseases and in the isolated perfused liver loaded with hydrophobic bile acids occurs through its effect on intestinal and hepatocyte transport systems.

Bile Acids and Salts↗
PubMed1995

Prevalence, severity, and risk factors of liver disease in blood donors positive in a second-generation anti-hepatitis C virus screening test.

In a cohort of 483 blood donors positive for antibody to hepatitis C virus on second-generation enzyme-linked immunosorbent, the confirmatory second-generation recombinant immunoblot assay (Ortho Diagnostic Systems) was positive in 172 cases (36%), indeterminate in 113 (23%), and negative in 198 (41%). We further studied 94 of the donors (recombinant immunoblot assay positive in 85, indeterminate in 6, and negative in 3). Alanine transaminase (ALT) activity, assayed on three occasions, was elevated in at least one assay in 85% of the 85 recombinant immunoblot assay-positive donors. Liver disease was present in 95% of these patients (chronic persistent hepatitis, 35%; chronic active hepatitis, 53%; cirrhosis, 7%). Ten of the 13 recombinant immunoblot assay-positive donors with normal ALT activity had liver disease; polymerase chain reaction testing for viral RNA was predictive of liver disease in most cases. Donors with cirrhosis differed significantly from cirrhosis-free donors in terms of age, sex ratio, ALT activity, and excessive alcohol consumption. Three of the 6 recombinant immunoblot assay-indeterminate donors (isolated C 22) who underwent histological examination had elevated ALT activity and liver disease. The 3 recombinant immunoblot assay-negative donors evaluated were free of liver disease. This study shows that anti-HCV second-generation enzyme-linked immunosorbent positivity is confirmed in fewer than 40% of blood donors by the second-generation recombinant immunoblot assay, and that liver disease is present in 95% of recombinant immunoblot assay-positive donors. Recombinant immunoblot assay positivity combined with viremia is frequently associated with the existence of liver disease, regardless of transaminase activity. Excessive alcohol consumption may be an important factor in the onset of cirrhosis in anti-HCV-positive blood donors.

Adult↗
PubMed1994

Ursodiol for the long-term treatment of primary biliary cirrhosis. The UDCA-PBC Study Group.

BACKGROUND: Ursodiol (ursodeoxycholic acid) therapy leads to major improvements in patients with primary biliary cirrhosis. The benefit of long-term treatment is uncertain. METHODS: We randomly assigned 145 patients with biopsy-proved primary biliary cirrhosis to receive ursodiol (13 to 15 mg per kilogram of body weight per day) (72 patients) or placebo (73 patients). After two years of follow-up, because of the benefit from ursodiol, all patients completing the study received ursodiol in an open trial and were monitored for two more years. The end points in the assessment of efficacy were as follows: progression of disease, as defined by the presence of hyperbilirubinemia, variceal bleeding, ascites, or encephalopathy; liver transplantation or a referral for that procedure; and liver transplantation (or a referral) or death. RESULTS: Disease progressed significantly less frequently in the ursodiol group than in the placebo group (P < 0.002; relative risk, 0.28; 95 percent confidence interval, 0.12 to 0.63). The probability of liver transplantation or a referral for that procedure and the probability of transplantation or death were significantly lower in the group assigned to ursodiol than in the group assigned to placebo (for transplantation alone, P = 0.003; relative risk, 0.21; 95 percent confidence interval, 0.07 to 0.66; for transplantation or death, P = 0.005; relative risk, 0.32; 95 percent confidence interval, 0.14 to 0.74). High bilirubin levels and, to a lesser extent, signs of cirrhosis at entry into the trial were predictive of disease progression, liver transplantation or a referral, and transplantation or death. CONCLUSIONS: Long-term ursodiol therapy slows the progression of primary biliary cirrhosis and reduces the need for liver transplantation.

Double-Blind Method↗
PubMed1994

Effects of bile acids and cholestasis on major histocompatibility complex class I in human and rat hepatocytes.

BACKGROUND/AIMS: Major histocompatibility complex (MHC) class I molecules, which are normally poorly expressed on the surface of hepatocytes, are overexpressed during cholestasis. The mechanisms responsible for this overexpression were examined. METHODS: The expression of class I molecules, assessed by flow cytofluorimetry, and the class I messenger RNA (mRNA) transcripts, assessed by Northern blot analysis, were measured on normal human hepatocytes in primary culture. RESULTS: Chenodeoxycholic acid induced an overexpression of MHC class I molecules, whereas ursodeoxycholic acid did not. The level of class I mRNA closely reflected that of the membrane protein. Moreover, cholestasis, induced in the rat by ligation-section of the common bile duct, increased the MHC class I mRNA level. Actinomycin D inhibited bile acid-induced class I transcription of rat hepatocytes in primary culture, whereas cycloheximide did not. Finally, class I mRNA expression was induced in hepatocytes by phorbol myristate acetate and by forskolin. This hyperexpression, as well as that observed with chenodeoxycholic acid, was suppressed by an inhibitor of protein kinase C and protein kinase A. CONCLUSIONS: Taken together, these results suggest that chenodeoxycholic acid, as interferon, activates protein kinase C and protein kinase A, resulting in the induction of MHC class I expression.

Adult↗
PubMed1994

Independent and combined actions of interleukin-1 beta, tumor necrosis factor alpha, and glucagon on amino acid metabolism in the isolated perfused rat liver.

Conflicting reports concerning the hepatic effects of interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) in the metabolic response to injury led us to investigate the influence of physiological concentrations of these cytokines on amino acid metabolism in the isolated perfused rat liver. IL-1 beta was ineffective at a concentration of 1 ng/mL, whereas TNF alpha (0.7 ng/mL) reduced the uptake of some of the main gluconeogenic amino acids (alanine, -55.3 +/- 4.9 v -72.9 +/- 13.7 nmol.min-1.g-1 in controls, P < .05) without affecting urea synthesis. TNF alpha increased glucose uptake by 237% and inhibited that of free fatty acids (-1.6 +/- 1.4 v -9.9 +/- 6.7 nmol.min-1.g-1 in controls, P < .05). IL-1 beta and TNF alpha potentiated glucagon-induced total amino acid uptake by 56% and 87%, respectively. They also affected glucagon-activated gluconeogenesis, leading to an initial potentiation of glucose release. Thereafter, IL-1 beta inhibited glucagon action, leading to an hepatic uptake of glucose. These results indicate that (1) in the conditions of the study, IL-1 beta has no direct effect on hepatic amino acid exchanges and utilization; (2) TNF alpha which exerted an inhibitory effect on these parameters, could be involved in the reduced amino acid exchanges during the end stage of sepsis; (3) the TNF alpha-induced increase in glucose uptake could be related to an inhibition of gluconeogenesis and/or to the activation of glucose utilization by Kupffer cells; (4) IL-1 beta and TNF alpha both potentiate the action of glucagon on hepatic amino acid uptake and utilization; and (5) complex interactions between Kupffer cells and hepatocytes on the one hand and between cytokines and hormones on the other hand could account for the differences in hepatic metabolism according to the stage of the response to injury.

Amino Acids↗
PubMed1994

Albumin messenger RNA as a marker of circulating hepatocytes in hepatocellular carcinoma.

BACKGROUND/AIMS: Hepatocellular carcinoma is one of the most frequent malignancies. Liver transplantation is theoretically the treatment of choice because it eliminates both the hepatocellular carcinoma and the cirrhosis. High frequency of relapse observed after liver transplantation may be explained by the existence of undetectable metastasis before transplantation. The aim of this study was to determine whether albumin messenger RNA (mRNA), a specifically hepatocyte-expressed gene, could be a marker of metastasis in hepatocellular carcinoma. METHODS: Albumin mRNA from circulating malignant hepatocytes was detected in the blood by reverse transcription followed by enzymatic amplification. RESULTS: Albumin mRNA was found in the blood of 3 patients with histologically proven metastatic hepatocellular carcinoma and in 9 of 21 patients with hepatocellular carcinoma and undetectable metastases, giving a percentage rate of 43, similar to the relapse rate following liver transplantation for hepatocellular carcinoma. None of the 8 patients with secondary liver cancer had detectable albumin mRNA. CONCLUSIONS: These results suggest that patients with hepatocellular carcinoma and no detectable albumin mRNA in the blood may be a subgroup with a low risk of relapse following liver transplantation.

Base Sequence↗
PubMed1994

Differential effects of chenodeoxycholic and ursodeoxycholic acids on expression of procoagulant activity by human monocytes.

Cell-mediated immunity is impaired during cholestasis, and there is evidence for the involvement of endogenous bile acids. The aim of this study was to evaluate the effects of individual bile acids on immunity and to determine whether monocytes are a target. The effects of bile acids on the procoagulant activity of human monocytes, a lymphocyte-dependent model of monocyte activation, were assessed. Chenodeoxycholic acid, one of the main human primary bile acids, had a concentration-dependent inhibitory effect on procoagulant activity expressed by endotoxin-stimulated mononuclear cells, with half-maximal and maximal inhibitions at 100 and 250 microM, respectively. The inhibitory concentrations were similar for the procoagulant activity of unstimulated mononuclear cells and for endotoxin-stimulated isolated monocytes. In contrast, ursodeoxycholic acid, a bile acid which has beneficial effects in cholestatic diseases, had no significant inhibitory effects at concentrations up to 250 microM. These results indicate that endogenous bile acids tend to inhibit monocyte activation, suggesting a potential role for primary endogenous bile acids in the immune defect associated with cholestasis; ursodeoxycholic acid, which is devoid of effects on the immune system, may potentially reverse cholestasis-induced immunodeficiency.

Blood Coagulation Factors↗