The aim of our study was to determine whether the minor polar components of virgin olive oil could have favorable effects (1) on fasting and postprandial lipid profile and (2) on low-density lipoprotein (LDL) composition and susceptibility to oxidation in vitro. Ten normolipidic subjects were included in a crossover study (two diet periods of 3 weeks) and received either virgin olive oil (OO diet) or oleic acid rich sunflower oil. An oral fat load was performed at the end of each period. The plasma lipid levels were not significantly different after both diets in the fasting and postprandial states. A few minor variations of the LDL composition were observed only in the postprandial lipemia, and they were different after both diets. The LDL oxidation susceptibility was evaluated by the formation of conjugated dienes. With LDL isolated in the fasting state, the diene production decreased (p = 0.0573) only after the OO diet. The dienes determined at time 0 and the maximal dienes obtained during the oxidation reaction decreased (p = 0.0145 and p = 0.0184, respectively) only after the OO fat load. Nevertheless, the diene production decrease was not significant (p = 0.0848). Our results suggest a mild effect of minor components of virgin olive oil related to a decrease of LDL susceptibility to oxidation; further analyses are necessary to give clear conclusions about their role.
1 alpha, 25-dihydroxyvitamin D3 was previously shown to induce cell death in brain tumour cell lines when added to the medium at micromolar concentration. In this paper we show that Cholecalciferol, a poor ligand of the vitamin D receptor, also induces cell death of HU197 human glioblastoma cell line and early passages cultures derived from a recurrent human glioblastoma. This finding suggests that the effects of vitamin D metabolites on brain tumour cells are at least partially independent from the activation of the classic nuclear receptor pathway. Vitamin D metabolites have been shown to activate the sphingomyelin pathway inducing an increase in cellular ceramide concentration. We determined the levels of sphingomyelin ceramide and ganglioside GD3 in Hu197 cells after treatment with cholecalciferol. A significant increase in ceramide concentration and a proportional decrease in sphingomyelin was already present after 6 hours of cholecalciferol treatment when no morphological changes were visible in the cultures. Treatment with ceramides (N-acetylsphingosine or natural ceramide from bovine brain) of the same cells also induces cell death. Similarly, treatment of the same cells with bacterial Sphingomyelinase also results in cell death. The demonstration of an increase in intracellular ceramide after cholecalciferol treatment and the ability of ceramide to induce cell death suggest that the sphingomyelin pathway may be implicated in the effect of vitamin D metabolites on human glioblastoma cells. Inhibition of ceramide biosynthesis by fumonisin B1 treatment did not alter the dose response curve of HU197 cells to cholecalciferol. Insensitivity to fumonisin B1 together with a decrease in sphingomyelin content after cholecalciferol treatment indicate that activation of sphingomyelinase should be responsible for the increase in intracellular ceramide concentration.
Five young patients with Niemann-Pick disease type B were treated with repeated implantations of amniotic epithelial cells, as a source of exogenous sphingomyelinase. This treatment abolished the recurrent infections, mainly of the respiratory tract, and led to other improvements of the general conditions of the patients. In particular, we noticed a disappearance of vomiting, a recovery from muscular hypotrophy, and significantly reduced pulmonary distress. In four subjects, who were in a prepuberal state, there was a puberal spurt with a concomitant burst of growth. In two cases, characterized by a greater than normal content of sphingomyelin in urinary sediments, a single implantation caused a sustained normalization of sphingomyelin and total phospholipids in the urine. Finally, sphingomyelinase activity of peripheral leukocytes, when assayed 0.5 to 4 months after some of the implantations, showed a rise to heterozygous values in 30-40% of the assays.
Partial or total loss of chromosome 22 is often associated with tumors of the central nervous system and in particular with meningiomas. As in the case of other tumors, the ganglioside pattern is modified in transformed tissues. Cytogenetic analysis of 30 human meningiomas has been performed and the results compared to biochemical analysis of ganglioside distribution on the membrane surface. The meningiomas were divided into 2 groups on the basis of the presence or absence of chromosome 22. Thirteen tumors exhibited partial or total monosomy of the chromosome, whereas 17 were normal or showed other chromosomal anomalies. The GM3 and GD3 content of the meningiomas belonging to the 2 groups revealed a significant correlation between amount and reciprocal ratio of these 2 gangliosides and cytogenetic data. Tumors with monosomy 22 had a higher content of ganglioside GD3 than samples without monosomy 22, where the main ganglioside was GM3. Other gangliosides such as GM1, GD1a, GD1b and GT were present in various amounts in the 2 groups. Considering the biosynthetic pathway of gangliosides, we hypothesize the involvement of a gene located on chromosome 22 in the regulation of the enzymes which catalyze either GD3 synthesis (sialyltransferase 2, SAT-2) or its degradation to GM3 (neuraminidase).
In a sample of meningosarcoma, obtained at the time of surgery, the amount of total gangliosides and phospholipids was examined, together with the cholesterol content and the distribution of different ganglioside and phospholipid species. The phosphatidylinositol, phosphatidylinositol-4-phosphate, phosphatidylinositol-4, 5-bisphosphate and phosphatidylcholine fatty acid composition was also analyzed. The ganglioside pattern in the meningosarcoma was different from the previously reported pattern in meningiomas of different histological origin, showing a higher concentration of GD3, indicating that the so-called b pathway of ganglioside biosynthesis was the preferred one in this type of tumor; moreover the percentage content of polysialylated gangliosides was very low. Cholesterol and phospholipid content was lower than in meningiomas; the phosphatidylcholine increase and the sphingomyelin decrease would indicate a lower membrane microviscosity, a characteristic of tumor cells. Phosphoinositide and phosphatidylcholine fatty acid analysis revealed a considerable amount of docosahexaenoic acid. This abnormal presence of this fatty acid could lead to the production, after receptor stimulation, of a diacylglycerol containing docosahexaenoic acid, which, in turn, could be responsible for an altered activation pattern of protein kinase C, in this way promoting carcinogenesis.
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