The hydroperoxides corresponding to the main molecular species of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were 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 bonds, 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 alpha-tocopherol and each hydroperoxide of PC and PE, and this association was particularly strong in PE (P < or = 0.0001). These results suggest that alpha-tocopherol exerts a stabilizing effect toward hydroperoxides, limiting their further degradation into peroxyl radicals. The protective effect of alpha-tocopherol could be more effective in PE because more polyunsaturated fatty acids were present.
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.
The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (Cat) were determined in human fibroblast cultures at four concentrations of exogenous alpha-tocopherol: 0.2, 2.5, 10 and 50 micrograms/ml of culture medium, or without alpha-tocopherol. Relationships between alpha-tocopherol levels and the activities of SOD and GPx were identified. The cellular alpha-tocopherol level correlated with GPx activity (p < or = 0.01) and inversely correlated with SOD activity (p < or = 0.003), but only when alpha-tocopherol was added to the culture medium. The variations in the cellular GPx/SOD ratio depended on the level of cellular alpha-tocopherol (p < or = 0.001). Furthermore, there was a strong inverse correlation between SOD and GPx activity (p < or = 0.0001). Cat activity did not correlate either with cellular alpha-tocopherol concentration, or with SOD or GPx activity. These results underline the complex interplay between alpha-tocopherol and other antioxidant systems in human fibroblast cultures.
Abstract Two types of human fibroblast strains were studied in culture. One was derived from abdomen skin and the other from abdominal muscle aponeurosis. Tissue‐specific differences were found between thése two cell strains. Skin fibroblasts had faster doubling time, smaller cell volume, and lower glucose consumption when compared to aponeurosis fibroblasts. Furthermore, extracellular amino acid variations showed some specific differences, in particular a lack of serine consumption in skin fibroblasts.
