Down-regulation of peroxisome proliferator-activated receptor-gamma gene expression by sphingomyelins.

We recently demonstrated that the sphingomyelin (SM) content of adipocyte membranes was negatively correlated with the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) in the subcutaneous adipose tissue of obese women with variable degrees of insulin resistance. We have now investigated whether SM really does have an impact on the expression of PPARgamma in 3T3-F442A adipocytes. Adding SM to the culture medium for 24 h caused a significant increase in SM content of adipocyte membranes and an acyl chain length-dependent decrease in the levels of PPARgamma mRNA and protein. The longer the acyl chain of the fatty acid of SM, the greater was the decrease in PPARgamma. These data suggest that the nature of the fatty acid is important in the regulation of PPARgamma by the SM pathway.

Urinary excretion of free cysteine in critically ill neonates.

UNLABELLED: In preliminary observations, significant amounts of free cysteine, a neurotoxic amino acid, were noted in the urine of asphyxiated or septic-shocked neonates. The present study was conducted to determine whether free urinary cysteine was elevated in these critically ill neonates compared with a control group, and to assess the clinical significance of this generation. Free cysteine was measured in the urine of newborn infants with perinatal asphyxia (n = 16) or neonatal sepsis (n = 14) and the urine of a control group (n = 10) by ion-exchange chromatography. Relationships between cysteine levels and the clinical severity, sulfite supply and neurological outcome of the patients were then studied. Urinary cysteine was 27.6 (15-49) mmol mol(-1) creatinine for the patients but was not detectable in the control group. Cysteine levels were correlated with the severity of neonatal septic shock but not with the grade of perinatal asphyxia and did not have a specific influence on the neurological outcome of these patients. The correlation between cysteine level and the severity of neonatal septic shock was indirect and probably linked to higher sulfite administration in this population. CONCLUSION: The mean daily supply of sulfites is high in critically ill neonates, mainly originating from dopamine and generating significant amounts of cysteine. Although a worsening effect attributable to cysteine on the neurological outcome of the patients could not be demonstrated, the appropriateness of cryptic administration of sulfites by way of drug excipients is called into question.

Adipocyte and erythrocyte plasma membrane phospholipid composition and hyperinsulinemia: a study in nondiabetic and diabetic obese women.

BACKGROUND: The cell functions involved in the action of insulin--receptor binding, enzyme and transporter activities--are controlled by membrane properties. We have previously shown that the fasting plasma insulin (FPI) concentration and the homeostasis model assessment (HOMA) estimate of insulin resistance are associated with the sphingomyelin concentration in the erythrocyte membranes of obese women. OBJECTIVES: (1) To study the distribution of phospholipid classes in the plasma membrane and their association with insulin resistance markers in the adipocyte, an insulin-sensitive cell in obese women. (2) To investigate the influence of diabetes in a small group of obese women treated by diet alone. (3) To compare the distribution of phospholipids in erythrocyte membranes in a subgroup of obese nondiabetic and diabetic women. SUBJECTS: Subcutaneous fat biopsies were taken from the abdominal region of 19 obese non-diabetic and seven obese type 2 diabetic women. Erythrocyte membrane assessment was performed in a subgroup of 10 of the 19 obese nondiabetic and in the seven diabetic patients. METHODS: The phospholipid composition of adipocyte and erythrocyte plasma membranes was analyzed by high performance liquid chromatography. RESULTS: FPI was positively correlated with the adipocyte membrane contents of sphingomyelin (P < 0.001), phosphatidylethanolamine (P < 0.05), and phosphatidylcholine (P < 0.01) in the obese nondiabetic women. Similar correlations were obtained with HOMA. A stepwise multiple regression analysis indicated that sphingomyelin accounted for 45.6 and 43.8% of the variance in FPI and HOMA values as an independent predictor. There was a similar positive independent association between FPI and SM in the erythrocyte membranes of the studied subgroup. Diabetes per se did not influence the independent association between SM membrane contents and FPI in both cell types. CONCLUSION: These results suggest a link between membrane phospholipid composition, especially SM, and hyperinsulinemia in obese women.

Adipocyte membrane phospholipids and PPAR-gamma expression in obese women: relationship to hyperinsulinemia.

We have shown that membrane sphingomyelin (SM) is an independent predictor of the variance of fasting plasma insulin (FPI) concentrations and the homeostasis model assessment (HOMA) estimate of insulin resistance in obese women. The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a key component in adipocyte differentiation that may also contribute to the sensitivity of cells to insulin. PPAR-gamma is activated by fatty acids, and the membrane composition may have an impact on the activity of PPAR-gamma and thus on the sensitivity of adipocytes to insulin. We investigated these possible links by determining the phospholipid contents of adipocyte membranes, the mRNA expression of PPAR-gamma, and the FPI and HOMA estimate of insulin resistance in obese women. The mRNA levels of tumor necrosis factor-alpha (TNF-alpha), which is suspected to play a role in insulin resistance and which downregulates PPAR-gamma expression, were also quantified. FPI and HOMA were strongly positively correlated with membrane SM (P < 0.005) and cholesterol (P < 0.005). PPAR-gamma mRNA levels were negatively correlated with FPI (P < 0.05) and HOMA (P < 0.05) and positively correlated with high-density lipoprotein (HDL) cholesterol (P < 0.05), membrane SM (P < 0.05), and cholesterol contents (P < 0.05). TNF-alpha mRNA levels were not correlated with membrane parameters. In stepwise multiple regression analysis, the variations in PPAR-gamma mRNA levels were mainly explained by HDL cholesterol (31.9%) and membrane SM (17.7%). Our study shows that the expression of PPAR-gamma, a major factor controlling adipocyte functions, the lipid composition of the membrane, and insulin sensitivity are probably closely associated in the adipose tissue of obese women.

Amphotericin B resistance and membrane fluidity in Kluyveromyces lactis strains.

The membrane fluidity of reduced-amphotericin B (AmB)-sensitivity Kluyveromyces lactis mutant strain is higher than that of the wild-type K. lactis strain. After culture of the K. lactis and K. lactis mutant cells in the presence of subinhibitory doses of AmB (10 and 125 mg/liter, respectively), the plasma membranes of both yeast strains also showed a higher fluidity than did those of control cells. High membrane fluidity was associated with changes in the structural properties of the membranes. Culture of the K. lactis and K. lactis mutant cells in the presence of AmB induced changes in membrane lipid contents. In particular, phospholipid contents were increased in both strains treated with AmB, compared with their corresponding counterparts. As a result, the sterol/phospholipid ratio decreased. The relative proportion of monounsaturated fatty acids also increased after AmB treatment. The saturated fatty acid/monounsaturated fatty acid ratio decreased in K. lactis and K. lactis mutant cells treated with AmB but also in K. lactis mutant control cells compared to that in the K. lactis wild strain. These changes in lipid composition explain the higher fluidity, which could represent a process of metabolic resistance of the yeasts to AmB.

Replication status and histological features of patients with triple (B, C, D) and dual (B, C) hepatic infections.

In patients with multiple hepatotropic viral infections (B and C, or B, C and D), the reciprocal influence of each virus remains controversial. The aims of this study were twofold: first, to determine the impact of multiple infection on the replication status of B, C and D viruses and on histological features; and second, to compare patients with multiple infection to patients infected only with the hepatitis C virus (HCV). We retrospectively included 50 patients with multiple infection and 50 control HCV patients, who were matched on independent factors associated with fibrosis, such as age, gender, alcohol consumption and duration of infection. The replication status of hepatitis B virus (HBV), HCV and hepatitis D virus (HDV), and histological lesions, were determined. In patients with multiple infection, HCV RNA was present less frequently (44% vs 98%, P < 0.001) and the prevalence of cirrhosis was higher (35% vs 8%, P < 0.001). Among patients with triple infection (n = 16), HBV replication was observed in 25%, HCV RNA was detectable in only two (P < 0.0001) and HCV viremia was significantly lower than in the matched HCV patients (0 vs 54.7, P < 0.0001). Among patients with dual infection (n = 34), HCV RNA was present less frequently in those with serological markers of active HBV infection than in those without (30% vs 79%, P = 0.01). Hence, multiple infection is associated with a decrease of HCV replication. Cirrhosis seems to be more frequently observed in patients with multiple infection. In patients with triple infection, serum HCV RNA and markers of HBV replication were absent in 80%, suggesting that HDV acts as a dominant virus. In patients with dual infection, HBV and HCV exert an alternative, dominant replication.

Outcome of Budd-Chiari syndrome: a multivariate analysis of factors related to survival including surgical portosystemic shunting.

The aim of this study was to assess the factors, including surgical portosystemic shunts, which affect survival in adults with Budd-Chiari syndrome. Multivariate retrospective analysis was performed using characteristics recorded at the time of diagnosis in 120 patients admitted from 1970 to 1992, of whom 82 were treated with surgical portosystemic shunts and 38 received only medical therapy. The 1-, 5-, and 10-year survival rates were 77 +/- 4%, 64 +/- 5%, and 57 +/- 6%, respectively. Survival was significantly better in the subgroup of patients diagnosed after versus before 1985. In both subgroups, and in patients with, as well as in patients without surgical shunts, 4 factors were found to be inversely and independently related to survival: age, response of ascites to diuretics, Pugh score, and serum creatinine. In patients diagnosed since 1985, an index combining these 4 factors allowed to differentiate patients with a good outcome (5-year survival 95%) from those with a poor outcome (5-year survival 62%; P <.05). There was no statistically significant and independent influence of surgical portosystemic shunts on survival. In conclusion, age, severity of liver failure, and presence of refractory ascites are the main prognostic factors in Budd-Chiari syndrome. Increased survival in recent years is consistent with improved management of hypercoagulable states as well as improved general care. It is uncertain whether surgical portosystemic shunting favorably modifies survival. Therefore, we recommend that surgical shunting should be restricted to management of refractory ascites or variceal bleeding in patients with otherwise good prognostic factors.

Implication of cell wall constituents in the sensitivity of Kluyveromyces lactis strains to amphotericin B.

In Kluyveromyces lactis, the cell wall compositions of Kl (ATCC 96897), a wild sensitive strain, and Klm (ATCC 96896), a strain resistant to amphotericin B (AmB), were shown to be very different, since the walls in the latter were significantly enriched in hexosamine, but had a reduced content in phosphate and amino acid. In both strains, the cell walls limited their sensitivity to this antifungal agent. The absence of cell wall increased the sensitivity of the cells to this polyene by 5 to 10-fold. When the cells were treated with enzymes such as pronase and chitinase in order to change the cell wall structure just before inoculation, the yeasts appeared more resistant to the antibiotic. However, treatments with chymopapain and phospholipase C did not significantly change the sensitivity of the two strains to this agent. Cells treated with acid phosphatase displayed a longer lag phase than the control cells. In addition, when cultured in the presence of AmB, the cells were less sensitive to this agent. The present results reveal that both a change in the ionic charges of the cell wall and an alteration in the cell wall structure modified the sensitivity of these yeast strains to AmB.

Hepatic venous outflow block caused by short-length hepatic vein stenoses.

In contrast with the well-recognized membranous obstruction of the inferior vena cava, short-length hepatic vein stenoses are not well-recognized causes of hepatic venous outflow block. The aim of this study was to ascertain the prevalence, causes, manifestations, and outcome of short-length hepatic vein stenoses. We performed a retrospective study of patients with short-length hepatic vein stenosis among 86 patients with hepatic venous outflow block who were seen between 1970 and 1992. There were 25 patients with short-length hepatic vein stenosis. A thrombogenic condition was identified in 14 patients (56%). The lesions of the accompanying hepatic veins in these patients were variable (short-length stenoses, thromboses, or nonspecific changes) and similar to that seen in patients without short-length hepatic vein stenosis. In 3 necropsied cases, the venous lesions were suggestive of fibrous sequela of prior thromboses. In patients with short-length hepatic vein stenosis, splenomegaly (28% vs. 55%, P < .05) and hypersplenism were significantly less common; serum transaminase (P < .001) and creatinine levels (P < .02) were lower, prothrombin was higher (P < .001), and 5-year survival was significantly better (Kaplan-Meier estimates: 80% vs. 50%, P < .05). In patients with hepatic venous outflow block, short-length hepatic vein stenosis is a common lesion that appears to be the sequela of localized thrombosis. Long-term anticoagulation and percutaneous angioplasty (with or without stenting) are potentially applicable in these lesions. The long-term results of these treatments merit further evaluation.

Flumazenil therapy for hepatic encephalopathy in cirrhotic patients: a double-blind pragmatic randomized, placebo study.

OBJECTIVE: To evaluate the effects of flumazenil on hepatic encephalopathy in patients with cirrhosis. DESIGN: Double-blind randomized study. SETTING: Liver intensive care unit over a 2-year period. PATIENTS: Fourteen patients with cirrhosis (median age 54 years, range 41-73 years), comprising 10 men and four women enrolled during 18 episodes of hepatic encephalopathy. METHODS: Placebo or flumazenil (1 mg at 0.1 mg/min infusion rate) was infused in coded vials. The patients' hepatic encephalopathy was graded clinically and by electroencephalography (EEG). RESULTS: In eight episodes of hepatic encephalopathy the placebo was infused first and no improvement occurred (0%). During 12 episodes of hepatic encephalopathy, flumazenil was administered and the EEG recording improved within 7 min (range 4-47 min; 12 out of 18 cases; 66 versus 0% for flumazenil versus placebo, respectively; P < 0.01); a modest clinical improvement in hepatic encephalopathy was observed within 83 min (range 30-340 min). The amount of flumazenil infused averaged 0.7 mg (range 0.4-1 mg). CONCLUSIONS: The infusion of 0.4-1 mg flumazenil results in a modest but rapid improvement in the EEG grading of hepatic encephalopathy and to a moderate but delayed improvement in the clinical grade of hepatic encephalopathy.