Hepatocytes from obese and lean Zucker rats adapted to a control (C) or a high-fat (HF) diet were prepared for the study of fatty acid (FA) uptake, partition between oxidation and esterification, and very low density lipoprotein (VLDL) production. A first 2-h kinetic study showed higher oleate uptake on a C diet by obese rat cells and an almost exclusive esterification to triacylglycerol (TG), VLDL secretion being 2.5-fold higher in obese rat cells and enhanced 1.4-fold in both genotypes in the presence of 0.7 mM oleate vs. 0.1 mM or no oleate. Fat feeding 1) decreased oleate uptake, esterification, incorporation into VLDL-TG, and mass VLDL-TG secretion and 2) abolished the VLDL-TG increase by 0.7 mM oleate. Similar but more pronounced effects were obtained in fat-fed lean animals. A second kinetic study using very short incubation times up to 1 h confirmed that fat feeding decreased oleate uptake and esterification, greatly stimulating its oxidation and production of acetoacetate (obese) or acetoacetate and beta-hydroxybutyrate (lean). Synthesis of lactate and pyruvate greatly decreased under HF feeding, remaining higher in obese rat cells. The drastic inhibition of labeled and total hepatic VLDL-TG secretion in obese and lean Zucker rats by the HF diet could be partly explained by decreased exogenous FA availability for VLDL-TG synthesis through its greater channeling toward oxidation and, indirectly, by the altered hepatocyte metabolic state.

Introduction. Without magnesium, vitamin D cannot be converted to its biolo- gically active form, a relationship that is often overlooked. Objective. The aim of this study was to estimate the frequency of hypovitaminosis D and that of hypomagnese-mia on the one hand, and to analyze the relationship between vitamin D status, magnesium, and plasma parathormone on the other hand. Population and methods. A retrospective descriptive-analytical,and epidemiological study was conducted on a 112 apparently healthy young adult subjects. For this purpose, bioassays of 25-hydroxy-vitamin D, magnesium and plasma parathormone were performed. Results. The frequency of hypovitaminosis D (serum 25-hydroxyvitamin D  30ng/mL) represented 88.39%. Hypomagnesemia affeted 43.75% of the studied population. A highly significant positive correlation was noted between plasma magnesium levels and vitamin D status of the subjects (R= 0.849; P = 0.000), whereas, a very significant negative correlation was observed between magnesium and plasma parathormone levels (R=-0.92 ; P = 0.000). Conclusion. A high frequency of hypovitamin D, a significant frequency of hypomagne-semia, and a positive correlation between plasma magnesium and vitamin D status are observed. Magnesium level is a determining factor in the variation of serum calcidiol concentrations that should be considered in the assessment of vitamin D status.

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Background: Hypovitaminosis D is a global public health problem. In Algeria, little work is done on the epidemiology of vitamin D deficiency targeting all at-risk populations. Objectives: The main objective of this study is to estimate the prevalence of hypovitaminosis D in healthy young adults. The secondary objectives are to identify the determinants of vitamin D status and to analyze the correlations between plasma calcidiol levels and other parameters of phosphocalcic metabolism. Material and methods: Cross-sectional descriptive, prospective and multicentric epidemiological survey of 945 subjects belonging to the Region of Blida (Algeria), assessment of 25-hydroxy-vitamin D, calcium, phosphorus, parathormone, alkaline phosphatase and albumin for each subject. The study also included a questionnaire to identify the determinants of vitamin D status in this population. Results: There is a high prevalence of hypovitaminosis D (calcidiol < 30 ng/ml), with 92.6% of subjects affected, of whom 27.5% had an insufficiency (calcidiol 20 -29 ng/ ml), however 65.1% of subjects were deficient (calcidiol < 20 ng/ml). No significant correlation was detected between 25-hydroxy-vitamin D and plasma calcium (R=0.051; P=0.115), a significant positive correlation was found between 25-hydroxy-vitamin D and phosphorus (R=0.146; P< 0,05). A negative correlation was detected between calcidiol and parathormone (R= -0.886; P< 0,05) and between calcidiol and alkaline phosphatase (R= -0.828; P< 0,05). Based on multivariate analysis, the 3 top risk factors that were associated with hypovitaminosis D are sun exposure time <30 min (adjusted OR =202.11, [95% CI]: 48.91; 835.10; P< 0,05), lack of knowledge about vitamin D (adjusted OR =46.45; [95% CI]: 20.84 ;103.52; P< 0,05), and dark phototype (adjusted OR =39.67; [95% CI]: 14.31; 109.99; P< 0,05). Conclusions: Hypovitaminosis D can be considered a public health problem in Algeria affecting young healthy populations. It is necessary to develop multisectorial programs in order to better address risk factors, particularly modifiable ones, and develop a strategy for prevention and care.