F. Lemonnier

Vitamin E deficiency and lipoperoxidation during adult respiratory distress syndrome.

Vitamin E (Vit E) is an important component of the lungs defense against oxidant injury. The aim of this study was to determine a) if adult respiratory distress syndrome (ARDS) was associated with a decrease in Vit E plasma level linked to an enhancement of plasma lipoperoxidation, and b) if this Vit E deficiency might be explained by malnutrition and/or a consumption defect. Vit E, lipoperoxides (LP), total lipids, and fatty acid plasma levels were measured in 12 patients with ARDS (Pao2 <60 torr with Fio2 0.6 on mechanical ventilation). At the onset of ARDS (T0), the decrease in Vit E plasma level was significant (p < .001) 7.73 ± 0.54 (n = 12) vs. 11.46 ± 0.55 mg/L (n = 7) in the control group (healthy subjects breathing room air). A significant (p < .05) increase in LP was simultaneously observed (4.12 ± 0.35 [In = 12] vs. 2.94 ± 0.30 nmol/ml [n = 17]) in the control group. At T0, LP were inversely correlated with Vit E plasma levels (r = .78, p < .01). Vit E deficiency was associated with low levels of total plasma lipids (3.68 ± 0.25 g/L) and plasma cholesterol (0.97 ± 0.07 g/L). Thus, the Vit E/total lipids ratio (2.18 ± 0.17 mg/g) was always above the accepted normal limit value for this ratio (0.8 mg/g). Significant decreases in essential fatty acid and linoleic acid (p < .01) and arachidonic acid (p < .05); and a significant (p < .05) increase in the oleic/linoleic acid ratio of 1.42 ± 0.16 vs. 0.91 ± 0.51 in the control group (n = 18) were simultaneously observed. During the 24 h after ARDS onset (n = 9), a significant decrease in LP was observed; i.e., −36% (p < .01) 6 h after ARDS onset, to −24% (p < .05) at 12 and 24 h, associated with a slight decrease in Vit E plotted against time, T0, 12, and 24 h after ARDS onset (Y = −0.03X + 7.34, p < .001) without any significant change in the oleic/linoleic acid ratio. We concluded that a) ARDS was associated with Vit E deficiency and enhancement of plasma lipoperoxidation; b) the low basal values of Vit E were linked to the low cholesterol and total lipid plasma levels, probably as a consequence of malnutrition; and c) during the course of ARDS, a significant Vit E plasma level decrease was observed, either as a consequence of increased utilization or as a consequence of decreased absorption.

Simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides obtained by lipoxygenase treatment.

A method for the simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides is described. Hydroperoxides were formed by incubation of phospholipids with lipoxygenase at pH 9.2. Silicic acid column chromatography (silica Sep-Pak column) was used to separate the phospholipids into phosphatidylcholine and phosphatidylethanolamine. A single C−18 reverse-phase column was employed to separate the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their hydroperoxides by high-performance liquid chromatography. The mobile phase consisted of 5% 10 mM ammonium acetate at pH 5 and 95% methanol. The molecular species of phosphatidylcholine and phosphatidylethanolamine were detected at 205 nm; the eluate was mixed with a chemiluminescence reagent (isoluminol and microperoxidase) and monitored by fluorometry. Under the experimental conditions used, three individual molecular species of both soybean phosphatidylethanolamine and phosphatidylcholine (18∶3/18∶2, 18∶2/18∶2 and 16∶0/18∶2), together with their corresponding hydroperoxides, were identified and quantitated.

Plasma Lipid Peroxides in Cholestatic Children

ABSTRACT. Plasma lipid peroxide levels were studied in 40 children with chronic cholestasis comprising 21 with syndromatic paucity of interlobular bile ducts (PILBD) and 19 with biliary atresia. Compared to the controls, mean lipid peroxide values were twice as high in children with biliary atresia (4.56±2.28 nmol/ml) and four times as high in those with PILBD (9.62±3.3 nmol/ml). These differences are highly significant. In patients with biliary atresia, the increase in lipid peroxide levels was clearly related to the bilirubin, cholesterol and phospholipid concentrations. In the PILBD group, however, there was little evidence of such a relationship. Vitamin E treatment seemed to have no effect on these increased lipid peroxide levels during the evolution of chronic cholestasis, and further investigations are necessary to clarify the pathological mechanisms involved.

Plasma Fatty Acid Composition and Lipid Peroxide Levels in Children with Paucity of Interlobular Bile Ducts

The total and free fatty acid composition of plasma and lipid peroxide concentrations was studied in 32 cholestatic children with syndromatic paucity of interlobular bile ducts (Alagilles syndrome). The mean lipid peroxide value in these patients was 8.80 +/- 3.70 nmol/ml, nearly 4 times higher than the mean control value. Compared to the control group, the patients exhibited significant variations in total fatty acids, and in particular a relative decrease in linoleic acid (from 29.5 +/- 6.1% in the controls to 19.1 +/- 8.03% in the patients) compensated by an increase in saturated and monounsaturated fatty acids. The plasma lipid peroxide levels were inversely correlated with the unsaturated/saturated fatty acids ratio in total fatty acids, and with the vitamin E status (vitamin E/total lipids). Most of the total and free fatty acid variations observed were largest in patients with severe jaundice. Dietary fat malabsorption and the increase in lipid peroxidation partly explain these results. Furthermore, in free fatty acids, we observed a marked increase in arachidonic acid (from 1.43 +/- 0.85% in the controls to 4.27 +/- 2.24% in the patients), suggesting abnormal eicosanoid synthesis.

Hydroperoxides of erythrocyte phospholipid molecular species formed by lipoxygenase correlate with α-tocopherol levels

The hydroperoxides corresponding to the main molecular species of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) where determined after lipoxygenase treatment of erythrocyte membranes from healthy children. This work was a preliminary study prior to applying this analytical procedure to erythrocyte membranes from children with diseases associated with vitamin E deficiency. The total molecular species corresponding to 20:4 and 22:6 associated with 16:0 and 18:0 were significantly higher in PE (26.94±4.70 nmol/mg protein) than in PC (20.14±6.70 nmol/mg protein); these concentrations represented 63% of the total molecular species in PE and 22% in PC. However, the concentrations of hydroperoxides produced from these polyunsaturated fatty acid molecular species were in the same order of magnitude in PC (3.98±1.56 nmol/mg protein) and in PE (3.61±1.63 nmol/mg protein). In contrast, the molecular species concentrations containing two double bounds, such as 16:0/18:2 and 18:0/18:2 and their corresponding hydroperoxides, were clearly more elevated in PC than in PE. There was a positive relationship between the concentrations of α-tocopherol and each hydroperoxide of PC and PE, and this association was particularly strong in PE (P≤0.0001). These results suggest that α-tocopherol exerts a stabilizing effect toward hydroperoxides, limiting their further degradation into peroxyl radicals. The protective effect of α-tocopherol could be more effective in PE because more polyunsaturated fatty acids were present.

Comparative study of extracellular amino acids in culture of human liver and fibroblastic cells

SummaryAmino acid concentrations are studied in the extracellular media of ten series of human fibroblast and liver cell monolayer cultures. These two cell types consume and produce ostensively the same amino acids. Among the nonessential amino acids, the most significant variations involve serine and aspartate which are decreased; α-alanine, glutamate, ornithine and proline are, on the contrary, increased. Among the essential amino acids, leucine, isoleucine and glutamine are preferentially decreased. The variations of some amino acids are correlated with the cell density. The interrelations which may exist between the variations of these different amino acids are discussed. Furthermore, the glycolytic activity of the cells studied is very high: 85% of glucose consumed is found in the form of lactate.

Modifications de ľamino-acidémie des cirrhotiques sous ľinfluence de sels d’ornithine

The plasma amino acid pattern of cirrhotic patients was determined before and after 24 h of continuous infusions of glucose, ornithine α-ketoglutarate (OαKG), ornithine chlorhydrate (ORN HCl) and sodiThe plasma amino acid pattern of cirrhotic patients was determined before and after 24 h of continuous infusions of glucose, ornithine alpha-ketoglutarate (O alpha KG), ornithine chlorhydrate (ORN HCl) and sodium ketoglutarate (alpha CGNa). Before treatment, leucine, isoleucine, valine and glutamine levels were low. Tyrosine and methionine levels were high. (See formula in text) was low. Glucose infusions had no effect. O alpha KG increased levels of leucine, isoleucine, valine, alanine and arginine. Threonine, serine, glycine, aspartic acid, methionine, hemicystine, tyrosine and phenylalanine were significantly lowered. (See formula in text) increased. ORN HCl and alpha CGNa did not induce similar changes.

Plasma vitamin E levels in children with cholestasis.

Plasma vitamin levels were assayed in 58 children presenting with chronic cholestasis. In the infants who developed cholestasis during the first weeks of life, vitamin E levels dropped below normal values after the age of 4 months. In the older children, vitamin E levels were not correlated with the etiology of cholestasis but with the degree of cholestasis, as expressed by serum bilirubin, serum bile acids, and fat absorption coefficient. We did not find any relationship between vitamin E levels and other biological parameters such as alkaline phosphatases, triglycerides, phospholipids, and cholesterol. These results further support the importance of vitamin E deficiency in chronic cholestasis of infants and children.

Comparative metabolic effects of fructose and glucose in human fibroblast cultures.

SummaryThe comparative metabolic effects of fructose and glucose were determined in human fibroblast cultures. Cells were grown in four different media containing 5.5 and 27.5 mM of glucose and fructose, respectively. For these two hexoses, we compared their uptake, consumption, and conversion into14CO2 and14C-lipids.D-Fructose was taken up in fibroblasts by an unsaturable process and its consumption was much smaller than that ofD-glucose. Whatever the experimental procedure, the glycogen content of cells grown in fructose media was significantly lower than of those grown in glucose media. Labeling of fructose and glucose with14C showed that more carbon from fructose than from glucose was incorporated into CO2 and glycerolipids. The relative distribution of14C in the different lipid fractions was similar for both hexoses.These results indicated that the pathways of intermediary metabolism in fibroblast cultures were influenced by the nature of the carbohydrate present in the culture medium and that fructose was a better lipogenic substrate than glucose in human fibroblast cultures.

Methionine metabolism and ultrastructural changes with D-galactosamine in isolated rat hepatocytes

The biochemical and morphological effects of 2, 10 and 100 mM of D-galactosamine (GalN) were studied in isolated rat hepatocytes during 2 h of incubation. Lactate dehydrogenase (LDH), alanine aminotransferase (ALAT) and cell viability did not change, whatever the concentration used. The variations observed, which were dose dependent, included a large drop in ATP levels and inhibition of RNA and protein synthesis. A very high concentration of GalN was necessary, however, to induce a significant decline in methionine adenosyltransferase activity compared to control cells. The use of L-[methyl-14C]methionine during cell incubation with GalN demonstrated a decrease of S-adenosyl-L-methionine (SAMe) and an accumulation of L-methionine content related to the GalN concentration. These results suggested that an hepatotoxic agent such as GalN was able to induce disturbances of methionine metabolism. Some of the ultrastructural changes observed were different from those previously found in vivo, in rats given GalN intraperitoneally, underlining the marked difference between in vivo and in vitro intoxication.