Effect of copper overload on the survival of HepG2 and A-549 human-derived cells.

We investigated the effect of copper (Cu) overload (20-160 µM/24 h) in two cell lines of human hepatic (HepG2) and pulmonary (A-549) origin by determining lipid and protein damage and the response of the antioxidant defence system. A-549 cells were more sensitive to Cu overload than HepG2 cells. A marked increase was observed in both the cell lines in the nitrate plus nitrite concentration, protein carbonyls and thiobarbituric acid reactive substances (TBARS). The TBARS increase was consistent with an increment in saturated fatty acids at the expense of polyunsaturated acids in a Cu concentration-dependent fashion. Antioxidant enzymes were stimulated by Cu overload. Superoxide dismutase activity increased significantly in both the cell lines, with greater increases in HepG2 than in A-549 cells. A marked increase in ceruloplasmin and metallothionein content in both the cell types was also observed. Dose-dependent decreases in α-tocopherol and ferric reducing ability were observed. Total glutathione content was lower in A-549 cells and higher in HepG2. Calpain and caspase-3 were differentially activated in a dose-dependent manner under copper-induced reactive oxygen species production. We conclude that Cu exposure of human lung- and liver-derived cells should be considered a reliable experimental system for detailed study of mechanism/mechanisms by which Cu overload exerts its deleterious effects.

n-3 Fatty acid supplementation in burned paediatric patients.

AIM: To determine the effect of dietary supplementation with n-3 fatty acids (FA) in paediatric burned patients who had less than 20% of total body surface affected. METHODS: Burned patients were randomly assigned into two groups, one of them received a supplement of n-3 FA during 5 weeks; the other group was considered as not n-3 supplemented burned group. A third group of no burned patients was selected as control. Blood samples were collected at admission and in burned groups at the final of the study. Plasma and erythrocyte phospholipid FA composition and some biochemical parameters related to the clinical evolution: total plasma proteins and C3 and C4 complement proteins were determined. RESULTS: In the early post-burn patients, there is an increase in saturated and monounsaturated FAs in plasma phospholipids, and a decrease in polyunsaturated FAs compared with control. These alterations are in favour of proinflammatory response to burn injury. In n-3 FA supplemented group, these changes were further reverted, and a favourable response in the amount of total plasma proteins and in C3 and C4 proteins of the complement system was demonstrated. CONCLUSION: Dietary n-3 FA supplementation might be beneficial for patients suffering thermal injury.

Effect of cyclosporine and sirolimus on fatty acid desaturase activities in cultured HEPG2 cells.

The aim of the present work was to evaluate the influence of cyclosporine (CsA) and sirolimus (SRL) on fatty acid (FA) desaturase activities. These enzymes (named Delta9, Delta6, and Delta5 desaturases) catalyze reactions leading to the biosynthesis of n-9, n-6, and n-3 FA families. n-3 FA family, derived from alpha-linolenic acid, is involved in the prevention of vascular events, which appear after successful kidney transplantation. Five groups of HepG(2) cells in culture were treated with either CsA (1 microg/microL and 2 microg/microL) or SRL (10 ng/mL and 20 ng/mL) for 3 days, including a control group without immunosuppressive treatment. We studied the incorporation and metabolic conversion of radioactive [1-(14)C]palmitic, linoleic, and eicosatrienoic acids. We also analyzed fatty acid composition. The distribution of radioactive metabolic products after incubation of these cells with [1-(14)C]palmitic acid revealed a decrease in Delta9 desaturase activity in the presence of each immunosuppressive drug: CsA = 0.61 +/- 0.01; SRL = 0.59 +/- 0.04 versus control = 0.79 +/- 0.05 (P < .01). We observed a significant increase in Delta6 and Delta5 desaturase activities under the influence of the immunosuppressive drugs: radiolabeled linoleic acid (CsA: 0.93 +/- 0.04; SRL: 1.02 +/- 0.03 vs control 0.60 +/- 0.03; P < .01) and eicosatrienoic acid (CsA: 1.12 +/- 0.02; SRL: 1.07 +/- 0.01 vs control 0.75 +/- 0.01; P < .01). In conclusion, CsA and SRL modulated the biosynthesis of polyunsaturated FAs, decreasing Delta9 desaturase and increasing Delta6 and Delta5 desaturase activities.

Long-chain polyunsaturated fatty acids in breast milk in La Plata, Argentina: relationship with maternal nutritional status.

Milk fat is the major source of energy for breastfed infants; it also supplies polyunsaturated fatty acids (PUFAs) essential for the development of brain, retina, and other organs. Maternal nutritional status is critical for the newborn, and little information exists regarding the PUFA status of vulnerable populations living in Southern regions. We studied the relationship between maternal nourishment and milk fatty acid composition. Mother nutritional status (normal, overweight or obese) was estimated on the body mass index. Milk protein, total lipid, and fatty acid composition were determined. Milk protein was not affected by mother's nutritional status. In obese mothers an increase in lipid content, linoleic acid, total n-6 and total PUFAs was observed comparing to the other groups. Disregarding the nutritional status, the ratio n-6/n-3 fatty acids was very high and the 22:6n-3 content was very low, when compared with those of mothers from other countries. This finding led us to urge Public Health officers to promote changes in the dietary habits of nursing women.

Role of lipopolysaccharide on the structure and function of alpha-hemolysin from Escherichia coli.

alpha-Hemolysin (HlyA) is a protein toxin (107 kDa) secreted by some pathogenic strains of E. coli. Several studies suggested the relationship between HlyA and lipopolysaccharide (LPS). We have studied experimentally the role of LPS on the stability and function of this toxin. The HlyA conformation in both, LPS-free and LPS-bound forms was investigated by tryptophan fluorescence. Studies about HlyA thermal and chemical denaturation indicated that its stability increased in the presence of LPS. On the other hand, the presence of negative and polar residues on the LPS reduced the tendency of HlyA to self-aggregation, and they may be the reservoir of calcium, cation essential for the lytic action of this toxin on red blood cells. These results suggest that HlyA and LPS are combined mainly via hydrophobic force to form an active toxin which stability is favored by the LPS.

Effect of simvastatin on the uptake and metabolic conversion of palmitic, dihomo-gamma-linoleic and alpha-linolenic acids in A549 cells.

It is well known that simvastatin affects cholesterol synthesis. Furthermore it inhibits growth and proliferation and perturbs fatty acid metabolism in some cell lines. We have studied the effects of simvastatin on the uptake and metabolism of exogenous fatty acid in the human lung adenocarcinoma A549 cells. Simvastatin inhibited the proliferation of A549, and caused an increment in phospholipid/cholesterol ratio due to an increment in phospholipid content without affecting cholesterol content. All the fatty acids were uptaken and metabolized in both control and treated cells. The conversion of palmitic, linoleic and dihomo-gamma-linoleic acids to their metabolites and products/precursor ratios for the desaturation and elongation reactions showed that simvastatin enhanced the Delta5 desaturation step and altered some elongating steps. The machinery for unsaturated fatty acid synthesis in A549 is quite sensitive to simvastatin and its effects could have important implication taking into account that highly unsaturated fatty acids are involved in the regulation of diverse cellular functions by themselves or through their metabolites.

The restoring effect of trifluralin and benznidazole on the abnormal fatty-acid pattern induced by Trypanosoma cruzi in the liver microsomes of infected mice.

The fatty-acid composition of liver lipids from mice infected with Trypanosoma cruzi (clone H510C8C3) or uninfected mice was investigated. The infected animals were treated orally for 30 days, with trifluralin (TFL) or benznidazole (BNZ), each at 100mg/kg.day, or only with the peanut oil used as the drug vehicle. The uninfected mice were also given the peanut oil. The treatments were stopped 10 days before the animals were killed. The liver microsomal lipids of each mouse were isolated and then analysed by gas-liquid chromatography. In terms of the total lipids, untreated infection evoked a significant increase in saturated fatty acids and the members of the n-9 fatty-acid family, with a concomitant decrease in the polyenoates of the n-3 and n-6 fatty-acid series. Each lipid subclass was affected to a different extent, the phospholipids being affected most. All lipid fractions, apart from the cholesterol esters, showed a significant increase in the proportion of n-9 isomers. Infection also produced a marked increase in the absolute amounts of triacylglycerides, cholesterol and cholesterol esters in liver microsomal membranes. After BNZ or TFL treatment, the fatty-acid pattern of mice that had been infected was indistinguishable from that of the control mice. The possible role of desaturase activity in the alterations observed is discussed.