Delta Hemolysin and Phenol-Soluble Modulins, but Not Alpha Hemolysin or Panton-Valentine Leukocidin, Induce Mast Cell Activation.

Mast cells are located at host interfaces, such as the skin, and contribute to the first-line defense against pathogens by releasing soluble mediators, including those that induce itching and scratching behavior. Here, we show that delta-hemolysin (Hld) and phenol soluble modulins (PSMs) PSMα1 and PSMα3, but not alpha-hemolysin (Hla) or Panton-Valentine leukocidin (PVL), induce dose-dependent tryptase, and lactate dehydrogenase (LDH) release by the HMC-1 human mast cell line. Using supernatants from isogenic strains, we verified that tryptase and LDH release was Hld- and PSMα-dependent. PSMα1 and Hld production was detected in 65 and 17% of human Staphylococcus aureus-infected skin abscess specimens, respectively, but they were produced in vitro by all clinical isolates. The results suggest that Hld and PSM-α1 produced in vivo during S. aureus skin infections induce the release of mast cell mediators responsible for itching and scratching behavior, which may enhance skin to skin transmission of S. aureus via the hands. As Hld and PSMs are upregulated by accessory gene regulator (agr), their association may contribute to the elective transmission of S. aureus strains with a functional agr system.

Dietary polyunsaturated fatty acids and heme iron induce oxidative stress biomarkers and a cancer promoting environment in the colon of rats.

The end products of polyunsaturated fatty acid (PUFA) peroxidation, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE), and isoprostanes (8-iso-PGF2α), are widely used as systemic lipid oxidation/oxidative stress biomarkers. However, some of these compounds have also a dietary origin. Thus, replacing dietary saturated fat by PUFAs would improve health but could also increase the formation of such compounds, especially in the case of a pro-oxidant/antioxidant imbalanced diet. Hence, the possible impact of dietary fatty acids and pro-oxidant compounds was studied in rats given diets allowing comparison of the effects of heme iron vs. ferric citrate and of ω-6- vs. ω-3-rich oil on the level of lipid peroxidation/oxidative stress biomarkers. Rats given a heme iron-rich diet without PUFA were used as controls. The results obtained have shown that MDA and the major urinary metabolite of HNE (the mercapturic acid of dihydroxynonane, DHN-MA) were highly dependent on the dietary factors tested, while 8-iso-PGF2α was modestly but significantly affected. Intestinal inflammation and tissue fatty acid composition were checked in parallel and could only explain the differences we observed to a limited extent. Thus, the differences in biomarkers were attributed to the formation of lipid oxidation compounds in food or during digestion, their intestinal absorption, and their excretion into urine. Moreover, fecal extracts from the rats fed the heme iron or fish oil diets were highly toxic for immortalized mouse colon cells. Such toxicity can eventually lead to promotion of colorectal carcinogenesis, supporting the epidemiological findings between red meat intake and colorectal cancer risk. Therefore, the analysis of these biomarkers of lipid peroxidation/oxidative stress in urine should be used with caution when dietary factors are not well controlled, while control of their possible dietary intake is needed also because of their pro-inflammatory, toxic, and even cocarcinogenic effects.

Phenol-soluble modulin α induces G2/M phase transition delay in eukaryotic HeLa cells.

Staphylococcus aureus is a gram-positive bacterium responsible for a wide range of infections. Host cell cycle alteration is a sophisticated mechanism used by pathogens to hijack the defense functions of host cells. We previously demonstrated that S. aureus MW2 (USA400) bacteria induced a G2/M phase transition delay in HeLa cells. We demonstrate here that this activity is triggered by culture supernatant compounds. Using size exclusion chromatography of the MW2 supernatant, followed by mass spectroscopy analysis of corresponding peaks, we identified phenol-soluble modulin α (PSMα) peptides as the likely candidates for this effect. Indeed, synthetic PSMα1 and PSMα3 caused a G2/M phase transition delay. The implication of PSMα in cell cycle alteration was confirmed by comparison of S. aureus Los Angeles County clone (LAC) wild-type with the isogenic mutant LAC∆psmα, which lacks the psmα operon encoding PSMα1-4. PSMα-induced G2/M transition delay correlated with a decrease in the defensin genes expression suggesting a diminution of antibacterial functions of epithelial cells. By testing the supernatant of S. aureus human clinical isolates, we found that the degree of G2/M phase transition delay correlated with PSMα1 production. We show that PSMs secreted by S. aureus alter the host cell cycle, revealing a newly identified mechanism for fostering an infection.

Malondialdehyde adduct to hemoglobin: a new marker of oxidative stress suitable for full-term and preterm neonates.

Oxidative stress may play a central role in the onset of many diseases during the neonatal period. Malondialdehyde (MDA) is a marker of lipid peroxidation. The aim of this study was to evaluate a new marker, the malondialdehyde adduct to hemoglobin (MDA-Hb), which is measured in red blood cells (RBCs) and thus does not require that an additional blood sample be drawn. In this prospective study, we first adapted the measurement method previously described to Hb solutions obtained from washed RBCs and then evaluated the suitability of the method for use in neonates. MDA-Hb concentrations were measured by liquid chromatography-mass spectrometry. We compared the concentrations of MDA-Hb between preterm and term neonates. Erythrocyte samples were collected at birth from 60 healthy neonates (29 full-term and 31 preterm), as well as from 50 preterm neonates with uncomplicated postnatal evolution during the first months of life. We found a significantly higher MDA-Hb concentration at birth in preterm neonates (P = 0.002). During the first months of life, MDA-Hb concentrations were 9.4 nanomol/g Hb in hospitalized preterm neonates. MDA-Hb could be used to assess oxidative stress in preterm neonates. Together with clinical variables, it could be a useful marker for oxidative stress exposition in these higher risk patients.

Adduct of malondialdehyde to hemoglobin: a new marker of oxidative stress that is associated with significant morbidity in preterm infants.

Preterm infants (PT) are particularly exposed to oxidative stress (OS), and a blood-sparing marker, the malondialdehyde adduct to hemoglobin (MDA-Hb), may be useful to accurately assess OS-related neonatal morbidity. In a prospective study, MDA-Hb concentrations were assessed in two groups of PT, one with and one without severe neonatal morbidity as estimated by a composite index of severe morbidity (ISM). All PT born in a single tertiary care NICU (<32 weeks and birth weight <1500 g) were consecutively included. MDA-Hb and blood glutathione (GSH) concentrations were measured by liquid chromatography-mass spectrometry during the first 6 weeks of life. Linear regressions and a multilevel model were fitted to study the relationship between MDA-Hb or GSH and ISM. Of the 83 PT (mean ± SD: 28.3 ± 2 weeks, 1089 ± 288 g), 21% presented severe neonatal morbidity. In the multivariate model, MDA-Hb concentrations were significantly higher in the ISM+ group than in the ISM- group during the first 6 weeks of life (P = 0.009). No significant difference in GSH concentrations was observed between groups (P = 0.180). MDA-Hb is a marker of interest for estimating oxidative stress in PT and could be useful to evaluate the impact of strategies to improve perinatal outcomes.

Estimating glomerular filtration rate in kidney transplant recipients: performance over time of four creatinine-based formulas.

BACKGROUND: The management of kidney transplant recipients requires accurate estimate of glomerular filtration rate (GFR). This study aims at evaluating the performance of four creatinine-based formulas for estimating the GFR (estimated GFR) in this population. METHODS: Performances of Cockcroft and Gault formula, Modification of Diet in Renal Disease (MDRD) simplified formula, Chronic Kidney Disease Epidemiology Collaboration formula, and Nankivell formula were assessed compared with inulin clearance taken as the gold standard for measuring GFR (measured GFR). Performances were assessed using the first measurements of GFR obtained in 1249 subjects. How estimated GFR tracks changes in measured GFR over time since transplantation in those patients with repeated measures was also assessed. RESULTS: The MDRD formula provided the best estimate of GFR with a mean bias of -0.5 mL/min/1.73 m, a standard deviation of bias of 12 mL/min/1.73 m, and a 30% accuracy at 85%. The MDRD formula also seemed to provide the best performance for estimating GFR, irrespective of age, stage of renal failure, and in people whose body mass index was more than 18.5 kg/m. This robustness is important in clinical practice. The performance of the four formulas was not modified by the posttransplant period. CONCLUSION: Even if 30% accuracy was suboptimal in the Kidney Disease Outcomes Quality Initiative guidelines, our results, obtained in a large number of patients, lead us to recommend using the MDRD formula to monitor GFR in kidney transplant recipients.

Influence of vitamins, trace elements, and iron on lipid peroxidation reactions in all-in-one admixtures for neonatal parenteral nutrition.

BACKGROUND: The purpose of this study was to evaluate the effect of vitamins, trace elements, or iron on lipid peroxidation in all-in-one parenteral nutrition (PN) admixtures for preterm neonates. METHODS: Malondialdehyde (MDA) concentrations were analyzed over a 24-hour period (H1-H24) in lipid-containing PN solutions that have a composition identical to that used in the routine clinical care of preterm infants. Six different solutions were prepared and evaluated when exposed to ambient light and light-protected conditions as follows: control (without vitamins [Vit], trace elements [TE], or iron [Fe] [Vit-TE-Fe-]), solution 1 (Vit+TE+Fe-), solution 2 (Vit+TE-Fe-), solution 3 (Vit-TE+Fe-), solution 4 (Vit-TE-Fe+), and solution 5 (Vit+TE+Fe+). RESULTS: MDA concentrations in PN solutions were significantly higher at H24 than at H0 when they contained multivitamins (P < .001), trace elements (P = .002), or iron saccharate (P = .018). MDA concentration was particularly high when all 3 micronutrients were present (P < .001) or when the solutions were exposed to ambient light. In solutions containing iron, MDA concentrations were elevated at H0, and levels did not change whether protected from (P < .001) or exposed to (P < .001) from light. CONCLUSIONS: The addition of vitamins and trace elements to PN solutions induces a significant increase in peroxidation products, which are lowered when admixtures are protected from light. Iron should not be included in these solutions, even if solutions are light-protected. By following these conditions it is possible to use all-in-one admixtures in the nutrition management of preterm infants.

Lipid peroxidation in all-in-one admixtures for preterm neonates: impact of amount of lipid, type of lipid emulsion and delivery condition.

AIM: To evaluate the effect of lipid emulsion composition and delivery condition on lipid peroxidation in typical all-in-one parenteral admixtures for preterm neonates. METHODS: Malonedialdehyde (MDA) concentrations were assessed in different all-in-one admixtures. We evaluated the effects of fat blend (three lipid emulsions) and the amount of lipids, as well as the effects of protecting bags and/or tubing from ambient light and storage for 72 h. MDA was measured by liquid chromatography/mass spectrometry. RESULTS: Three hundred and sixty samples were collected from 114 admixtures. Neither the type of lipid (p = 0.43) nor the interaction between light and type of lipid (p = 0.49) had any influence on final MDA concentrations, but the increase in MDA concentration at 24 h (T(24)) was related to light exposure (p < 0.001). The increase in MDA concentration was related to the increase in lipid amount in the admixture at T(0) (r = 0.77) and T(24) (r = 0.86). MDA concentrations in solutions stored for 72 h showed no significant increase, with no difference between the three lipid emulsions (p = 0.69). CONCLUSION: All-in-one admixtures may be interesting for the parenteral nutrition of preterm neonates. Protection from light and restricting the amount of lipid to what is required for appropriate energy provision are essential to limit lipid peroxidation.

Preserved residual renal function is associated with lower oxidative stress in peritoneal dialysis patients.

BACKGROUND: Residual renal function (RRF) correlates with survival in peritoneal dialysis (PD). We investigated the association between oxidative stress and RRF in PD. METHODS: Adequacy of dialysis, total and free malondialdehydes (MDA), and lipid hydroperoxides (LHP) were obtained from 23 stable PD patients. RESULTS: Free MDA level decreased with total weekly Kt/V urea (r = -0.51, P = 0.013) and urinary Kt/V (KRU) (r = -0.53, P = 0.009), but not with peritoneal Kt/V. Similar results were found with LHP level. In multivariate analysis, total weekly Kt/V urea and KRU remained associated with free MDA and LHP, independently of gender, nutritional or inflammatory status, and peritoneal permeability. CONCLUSION: A preserved RRF is associated with lower serum levels of lipid peroxidation products among PD patients.

Structural equations to model relationships between pulmonary function, fatty acids and oxidation in cystic fibrosis.

OBJECTIVE: To illustrate the advantages of structural equation models in biomedical research using the complex example of cystic fibrosis. MATERIAL AND METHODS: 595 blood samples from 312 patients were tested. The model studied the effects of age, BMI and clinical condition on seven major latent variables: pulmonary function, lipid oxidation status, vitamins A and E, glutathione, carotenoids, two essential fatty acids and arachidonic acid. RESULTS: The model confirmed previous associations: positive (fatty acids, arachidonic acid, carotenoids and vitamins with pulmonary function and with lipid oxidation) and negative (glutathione with pulmonary function). It also verified the decrease in fatty acids during bronchial exacerbation and the increase in fatty acids and lipid oxidation after antibiotic treatment. Above all, the model revealed new positive associations between lipid oxidation and carotenoid levels and between lipid oxidation and vitamin A and E levels. CONCLUSIONS: Structural equations dealt easily with the great number of outcome variables of the example. They deserve a central place in biomedical issues involving too many correlated factors to help physicians and statisticians conceive biological models that best represent reality.

Sensitization by docosahexaenoic acid (DHA) of breast cancer cells to anthracyclines through loss of glutathione peroxidase (GPx1) response.

Docosahexaenoic acid (DHA, a lipid of marine origin) has been found to enhance the activity of several anticancer drugs through an oxidative mechanism. To examine the relation between chemosensitization by DHA and tumor cells antioxidant status, we used two breast cancer cell lines: MDA-MB-231, in which DHA increases sensitivity to doxorubicin, and MCF-7, which does not respond to DHA. Under these conditions, reactive oxygen species (ROS) level increased on anthracycline treatment only in MDA-MB-231. This was concomitant with a decreased cytosolic glutathione peroxidase (GPx1) activity, a crucial enzyme for protection against hydrogen and lipid peroxides, while major antioxidant enzyme activities increased in both cell lines in response to ROS. GPx-decreased activity was accompanied by an accumulation of glutathione, the GPx cosubstrate, and resulted from a decreased amount of GPx protein. In rat mammary tumors, when a DHA dietary supplementation led to an increased tumor sensitivity to anthracyclines, GPx1 activity was similarly decreased. Furthermore, vitamin E abolished both DHA effects on chemotherapy efficacy enhancement and on GPx1 inhibition. Thus, loss of GPx response to an oxidative stress in transformed cells may account for the ability of peroxidizable targets such as DHA to enhance tumor sensitivity to ROS-generating anticancer drugs.

Bacterial adhesion to conventional hydrogel and new silicone-hydrogel contact lens materials.

BACKGROUND: As bacterial adhesion to contact lenses may contribute to the pathogenesis of keratitis, the aim of our study was to investigate in vitro adhesion of clinically relevant bacteria to conventional hydrogel (standard HEMA) and silicone-hydrogel contact lenses using a bioluminescent ATP assay. METHODS: Four types of unworn contact lenses (Etafilcon A, Galyfilcon A, Balafilcon A, Lotrafilcon B) were incubated with Staphylococcus epidermidis (two different strains) and Pseudomonas aeruginosa suspended in phosphate buffered saline (PBS). Lenses were placed with the posterior surface facing up and were incubated in the bacterial suspension for 4 hours at 37 degrees C. Bacterial binding was then measured and studied by bioluminescent ATP assay. Six replicate experiments were performed for each lens and strain. RESULTS: Adhesion of all species of bacteria to standard HEMA contact lenses (Etafilcon A) was found to be significantly lower than that of three types of silicone-hydrogel contact lenses, whereas Lotrafilcon B material showed the highest level of bacterial binding. Differences between species in the overall level of adhesion to the different types of contact lenses were observed. Adhesion of P. aeruginosa was typically at least 20 times greater than that observed with both S. epidermidis strains. CONCLUSIONS: Conventional hydrogel contact lenses exhibit significantly lower bacterial adhesion in vitro than silicone-hydrogel ones. This could be due to the greater hydrophobicity but also to the higher oxygen transmissibility of silicone-hydrogel lenses.

Polyunsaturated fatty acids modulate NOX 4 anion superoxide production in human fibroblasts.

The strong ROS (reactive oxygen species) production, part of an antioxidant response of human fibroblasts triggered by DHA (docosahexaenoic acid; C(22:6,n-3), served as a model for deciphering the relative contribution of NOX (NADPH oxidase) to ROS production, as the role of this enzymatic system remains controversial. Using hydroxyethidium fluorescence for fibroblast ROS production, RT (reverse transcriptase)-PCR for NOX 4 mRNA quantification and mRNA silencing, we show that ROS production evolves in parallel with the catalytic activity of NOX and is suppressed by siNOX 4 (small interference oligonucleotide RNA directed against NOX 4) silencing. Apocynin and plumbagin, specific inhibitors of NOX, prevent ROS production in this cellular model and confirm the role of NOX 4 for this production. Furthermore, we show that, in cell lysates, NOX 4 activity can be modulated by PUFAs (polyunsaturated fatty acids) at the micromolar level in the presence of calcium: NOX 4 activity is increased by arachidonic acid (C20:4,n-6) (approximately 175% of the control), and conjugated linoleic acid (C18:2 [9Z,11E]) is a potent inhibitor (50% of the control). Unexpectedly, intracellular superoxide dismutase does not participate in the modulation of this ROS production and the opposite effects of some PUFAs, described in our experiments, could suggest another way of regulating NOX activity.

Fatty acids platelets and oxidative markers following intravenous n-3 fatty acids administration in cystic fibrosis: An open pilot observational study.

BACKGROUND: An imbalance in the ratio of arachidonic acid and docosahexaenoic acid (DHA) was found in cystic fibrosis (CF) affected tissues and was suggested to promote inflammation. Several studies have shown that the long chain n-3 fatty acids reduced inflammatory activity while others have highlighted prooxidant activity of DHA at high concentrations. The aim of our study was to evaluate the effects of an intravenous fish-oil emulsion enriched with n-3 FA in patients with CF on plasma and platelet FA composition and peroxidation markers. METHODS: 13 patients with CF received one IV emulsion per week of 2 mL/kg fish-oil n-3 emulsion for 12 weeks. RESULTS: There was a significant increase in 20:5 n-3 and 22:6 n-3 platelet FA composition, no variation in 20:4 n-6, a decrease in n-9. There was no variation in plasma FA composition. Specific urinary markers of lipid peroxidation derived from n-3 and n-6 showed a very high level before infusion compared with usual values in healthy subjects which was not affected by treatment. A significant weight loss and a decrease in reduced glutathione were observed in adult patients. CONCLUSIONS: The intravenous administration of n-3 FA in CF patients induced a significant modification in platelet FA composition but no modification of oxidative markers. However, the weight loss and the decreased level in reduced glutathione observed in adult patients may suggest a potential deleterious activity for some patients. Further studies are necessary to determine the optimal dose and route for long chain FA administration required to reach a potential beneficial effect.

Conjugated linoleic acid, unlike other unsaturated fatty acids, strongly induces glutathione synthesis without any lipoperoxidation.

Enhancement of the redox status of cells is a cytoprotective strategy against oxidative damage. We recently showed that DHA upregulates glutathione (GSH) content via an induction of its related enzymes gamma-glutamylcysteine ligase and glutathione reductase. In the present study, we investigated the effects of eight other fatty acids on the redox status and lipid peroxidation of human fibroblasts. After 48 h, only arachidonic acid and conjugated linoleic acid (CLA) enhanced GSH content through an induction of gamma-glutamylcysteine ligase. CLA was more potent than arachidonic acid in inducing GSH synthesis. For all the fatty acids tested, lipoperoxidation, estimated by cell malondialdehyde measurement, did not differ from that of controls at 48 h but dramatically increased at 7 d, except for CLA. Lipoperoxidation is associated at 7 d with a high level of reactive oxygen species and with increased haemoxygenase-1 and cyclooxygenase-2 mRNA expression. As demonstrated by a tert-butylhydroperoxide cytotoxicity test, the GSH synthesis obtained with arachidonic acid is not sufficient to protect the cells, whereas this protective effect was obvious with CLA at 48 h as well as at 7 d. The present results show that CLA is the only PUFA able to induce GSH synthesis without any change in oxidative balance, whereas an upregulation of cyclooxygenase-2 by other PUFA is concomitant with an overproduction of malondialdehyde and reactive oxygen species. The particular hairpin conformation obtained for CLA by molecular modelling could account for this specific biological effect.

Systemic markers of the redox balance and apolipoprotein E polymorphism in atherosclerosis: the relevance for an integrated study.

Prospective studies have demonstrated that an imbalance between oxidative damage and antioxidative protection can play a role in the development and progression of atherosclerosis. Also, genotypes with the apolipoprotein E epsilon4 allele have been associated with an increase risk for this pathology. Based on this knowledge, the aim of this study was to evaluate indicators of the redox balance, trace elements, and apolipoprotein E allelic profile in subjects from the Lisbon population with clinically stable atherosclerosis, at risk for atherosclerotic events, and in healthy subjects for comparison. The activities of superoxide dismutase in erythrocytes and glutathione peroxidase in whole blood, plasma total thiols, and serum ceruloplasmin were kept unchanged among the three groups. Serum alpha- tocopherol was increased in atherosclerotic patients. Total malondialdehyde in serum and protein carbonyls in plasma, which are indicators of lipid and protein oxidative damage, respectively, reached their highest values in risk subjects. The concentrations of potassium and calcium, in plasma and in blood cells, were slightly elevated in patients and might reflect an electrolytic imbalance. Regarding the apolipoprotein E polymorphism, atherosclerotic patients had an increased incidence of the high-risk genotypes for atherogenesis (epsilon3/epsilon4 and epsilon4/epsilon4). A multivariate model applied to the general population using most of the parameters clearly separated the three groups at study (i.e., the healthy group from the steady-state group of risk disease and from the atherosclerotic one). As shown by us, the usefulness of biochemical and complementary genetic markers is warranted for a better knowledge on atherosclerosis molecular basis.

Evaluation of IGL-1 preservation solution using an orthotopic liver transplantation model.

AIM: To compare, in a pig liver transplantation model, the protective effect of UW with that of IGL-1, a high-sodium preservation solution containing polyethylene glycol (PEG) as an oncotic supply. METHODS: All livers were harvested and grafted orthotopically according to standard techniques. The livers were washed out and preserved for 7 h in IGL-1 (n = 6) or in UW solution (n = 7) at 4 degree centigrade. In a sham group (n = 4), the livers underwent a 60-min warm ischemia at 37 degree centigrade. The hepatocellular injury was assessed in organ preservation solution washed out from the graft at the end of ischemic storage (before revascularization), and in serum 2 h after reperfusion and daily for up to 6 d. RESULTS: Livers preserved in IGL-1 solution released markedly less AST than that preserved in the UW solution before and after revascularization (P < 0.05). Besides, the activity of creatine kinase-BB, a marker of sinusoidal lining cells injury, was higher in the UW group than in the IGL-1 group (P < 0.05). Histological results showed less necrotic regions in livers preserved in IGL-1 solution; however, no difference was observed for inflammation. CONCLUSION: IGL-1 liquid effectively protects parenchymal and non-parenchymal cells against preservation-reperfusion injuries.

Docosahexaenoic acid enhances the antioxidant response of human fibroblasts by upregulating gamma-glutamyl-cysteinyl ligase and glutathione reductase.

The chemopreventive effects of dietary n-3 PUFA in various pathologies has so far remained controversial, and we were interested in studying their potential influence on cell redox status. DHA (22 : 6n-3), a typical highly unsaturated n-3 PUFA, was used at 30 micromol/l in a model of human fibroblast cell culture. A dose-response effect, roughly linear, was checked for DHA between 0 and 60 micromol/l, and was accompanied by a large increase in intracellular GSH content. A time course study of this effect shows that, after a short fall, as soon as 4 h after the beginning of the experiment, the large increase in the GSH content was associated with elevated catalytic activities of gamma-glutamyl-cysteinyl ligase, glutathione reductase and glutathione S-transferase. This coordinated response is characteristic of an antioxidant response and was confirmed by the induction of expression of mRNA for gamma-glutamyl-cysteinyl ligase, glutathione reductase and haem-oxygenase. This large increase in the GSH content contributes to decreasing the reactive oxygen species level, as assessed by the decreased accumulation of dichlorofluorescein inside cells. To our knowledge, this is the first report on a specific and potent effect of DHA for decreasing the oxidative stress of human fibroblasts.

Differential sensitization of cancer cells to doxorubicin by DHA: a role for lipoperoxidation.

Polyunsaturated fatty acids have been reported to enhance the cytotoxic activity of several anticancer drugs. In the present study, we observed that doxorubicin chemosensitization of breast cancer cell lines by docosahexaenoic acid (DHA, a long-chain omega-3 polyunsaturated fatty acid) was cell-line selective, affecting MDA-MB-231 and MCF-7 dox (a doxorubicin-resistant cell line) but not the parental MCF-7 cell line. DHA supplementation led to an increase in membrane phospholipid DHA level, but did not induce changes in intracellular [(14)C]doxorubicin accumulation. In MDA-MB-231, doxorubicin efficacy enhancement by DHA was linked to an increase in malondialdehyde level, a final product of lipid peroxidation. DHA elicited by itself a 3.7-fold malondialdehyde level increase, additive to that induced by doxorubicin. Addition of doxorubicin to DHA further increased the glutathione level, indicative of the generation of an oxidative stress. In contrast to MDA-MB-231, doxorubicin did not increase the malondialdehyde level in MCF-7, although DHA induced lipid peroxidation. Therefore in MCF-7, lipid peroxidation induced by DHA itself was not sufficient to trigger an oxidative stress and to subsequently increase sensitivity to doxorubicin. These data indicate that the differential effect of DHA among cells on drug toxicity results from a differential oxidative response to doxorubicin. Chemosensitization through fatty acids appears as a new promising adjuvant therapeutic paradigm, since omega-3 fatty acids are physiological molecules found in food and are nontoxic in vivo.

[Evaluation of IGL-1, a new organ preservation solution: preclinical results in renal transplantation]. / Evaluation de IGL-1, une nouvelle solution de conservation d'organes: résultats pré-cliniques en transplantation rénale.

INTRODUCTION: Renal ischaemia and reperfusion lesions partly determine short-term and long-term graft survival. Organ preservation conditions appear to play a decisive role. This article presents the preclinical experimental results obtained in renal transplantation with an extracellular organ preservation solution, in which polyethylene glycol (PEG) is used as colloid. METHODS AND RESULTS: The effects of inversion of Na+ and K+ gradients in the IGL-1 preservation solution compared to UW and replacement of hydroxylethyl starch (HES) by PEG were evaluated in an ex vivo isolated, perfused rat kidney model and then in a pig renal autotransplantation model. In these experimental models, after 24 hours of static storage, the sodium reabsorption fraction correlated with the quality of tubular function of the kidney and the glomerular filtration rate were constantly better in the IGL-1 group than in the UW group. In vivo, in the pig, resumption of renal function was significantly better in the IGL-1 group and histological examination demonstrated a significant reduction of expression of Major Histocompatibility Complex (MHC) type II, an indirect marker of inflammation, but also a reduction of markers of apoptosis and fibrosis for kidneys preserved in IGL-1. CONCLUSION: In animal renal transplantation, IGL-1 ensures better resumption of renal function than UW, which currently remains the "gold standard"preservation solution. Further studies must be conducted to determine whether this new generation solution can replace UW as the reference solution.