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P Guiraud

Publications and source records attributed to P Guiraud.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Effect of zinc supplementation on resistance of cultured human skin fibroblasts toward oxidant stress.

In purified system zinc has been shown to have an antioxidant role. Its effects on the resistance of cultured cells towards oxidative stress in vitro were examined. Diploid human skin fibroblasts were grown for 21 d in culture media (RPMI 1640 containing 15% fetal calf serum) added with different zinc (Zn) concentrations (100, 125, and 150 microM as Zinc chlorur ZnCl2). In comparison, cell controls were grown in standard culture media (6.5 microM Zn). The intracellular zinc levels of treated fibroblasts increased from 3- to 7-fold (2330 +/- 120 ng/mg protein in 150-microM Zn-treated cells versus 331 +/- 21 ng/mg protein in control cells). The intracellular copper increased 3- fold whereas the iron content slightly but not significantly decreased. The index of basal lipid peroxidation measured as thiobarbituric acid reactants (TBARs) of zinc-supplemented cells was lower than that of non zinc supplemented controls (0.89 mumol/g protein in 150 microM Zn-treated cells versus 1.59 mumol/g protein in controls). At these high doses of zinc, fibroblasts expressed lower antioxidant metalloenzymes activities. Diminished TBARs in Zn treated cells tends to support that Zn acts protectively against free radical mediated damage. However when the cells were challenged with extracellular oxidant stresses mediated by hypoxanthine/xanthine oxidase or hydrogen peroxide (H2O2), an increased toxicity in Zn-supplemented cells was observed. When we applied an intracellular oxidative stress as UV-B or UV-A radiation, Zn-treated fibroblasts were more resistant than cells grown in normal medium. If Zn has shown antioxidant effect in some in vitro or in vivo systems our observations clearly demonstrate that this role is not mediated by antioxidant metalloenzymes.

Cell Survival↗
PubMedDate not supplied

Cultured human skin fibroblasts absorb 65Zn. Optimization of the method and study of the mechanisms involved.

The radioactive isotope 65Zn was used to study the incorporation of zinc by cultured human skin fibroblasts. The development of the method for studying cell uptake of 65Zn in a minimal synthetic medium is presented. Kinetics carried out on control cultures up to 240 min indicated that zinc uptake occurred in three phases, the first being the most rapid. Temperature and pH affect zinc uptake, in favor of an active transport process. In addition, the rate of incorporation is considerably decreased during the first phases after adding potassium cyanide, during the last phases after adding sodium iodoacetate, and during all the phases if dithioerythritol is used. A hypothesis is therefore proposed according to which several types of mechanisms would be involved in zinc uptake by fibroblasts. At least a part of these mechanisms is energy-dependent.

Adult↗
PubMedDate not supplied

Removal of herbicides from liquid media by fungi isolated from a contaminated soil.

Fungi were isolated from soil samples corresponding to pesticide-contaminated soil (CS) and noncontaminated soil (NCS) in the Annaba vicinity (Algeria) and identified. The number of isolates obtained from CS and NCS were 263 and 288, respectively. The most frequent species (Aspergillus fumigatus, A. niger, A. terreus, Absidia corymbifera, and Rhizopus microsporus var microsporus) were not sensitive to the pesticides. The growth of the genus Trichoderma was inhibited by the pesticides, while genera Absidia and Fusarium were stimulated. The 53 species isolated were assayed for their ability to remove metribuzin from liquid medium. Only Botrytis cinerea from NCS and Sordaria superba and Absidia fusca from CS removed more than 50% of the compound after 5 d. Metamitron was very resistant. Among the 21 species tested, only Alternaria solani (from NCS), Drechslera australiensis (from CS and NCS), and Absidia fusca (from CS) reduced the concentration in the medium more than 10% (10-16%). Twelve species were grown with linuron, seven of them were inefficient in removing this compound. The two strains of Sordaria macrospora yielded 22 to 25% depletion, while Botrytis cinerea depleted linuron almost completely. Among the 31 species assayed for their ability to eliminate metobromuron, Botrytis cinerea (from CS and NCS) depleted almost completely the chemical from the medium. Rhizopus oryzae and Absidia fusca from CS removed 40 and 47% of the compound, respectively. No systematic relationships were observed between the soil contamination and herbicide elimination capacities of soil fungi. Absidia fusca and Botrytis cinerea were particularly interesting for bioremediation purposes because they were able to transform efficiently three of the four compounds assayed.

Biodegradation, Environmental↗
PubMedDate not supplied

Influence of copper, iron, and zinc on the physicochemical properties of parenteral admixture.

A parenteral admixture composed of 25% of 20% Intralipid, 25% of Azonutril 25, 37.5% of 30% Glucose and 12.5% of 50% Glucose was supplemented with copper, iron and zinc in the organic (gluconate) or inorganic (chloride) form at the following usual final concentrations: copper 0.24 mg/L, iron 0.50 mg/L, zinc 2.00 mg/L. The mixture was stored at 4 degrees C and at 25 degrees C for 24, 48, and 72 hours, and for one week. Determination of the pH indicated good stability of the mixture containing the trace elements in the gluconate form. A significant decrease in the pH of the mixture containing the trace elements as chlorides was noted after one week of storage at both temperatures. Particle size analysis revealed no significant variations between the two formulations after one week of storage. Flocculation kinetics confirmed the results obtained with the other two methods used to determine physicochemical stability. In addition, the kinetics indicated that the possibilities of coalescence processes are highly reduced in all cases. It may be concluded that the two type of mixtures remain stable for Seven days at 4 degrees C and 25 degrees C. However, mixtures containing trace elements in gluconate form should be chosen in cases of longer storage.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Effect of oestrone on the natural killer (NK) cell activity, antioxidant status and tumour growth in athymic mice xenografted with human tumours.

Natural killer (NK) cells have been described as being very sensitive to oxidative stress. Thus it has been previously shown that chronic administration of oestrone in drinking water of athymic mice xenografted with a wide variety of human tumours, increases their growth and development. In this study an investigation was made to see whether oestrone supplementation could influence the NK cell activity by changes in the antioxidant defences which result in an oxidative stress and influence the proliferation of tumours. Supplementary oestrone was administered in drinking water of athymic mice xenografted with two different human tumours which lack oestrogen receptors: a bladder carcinoma and a small-cell lung carcinoma. The growth of the urothelial carcinoma was poorly affected by oestrone, but oestrone significantly (p<0.01) increased the proliferation of the small-cell lung carcinoma. The average uterus weight was increased by 62% in oestrone treated mice with no modifications in plasma zinc and selenium status, nor in erythrocyte copper zinc superoxide dismutase level. Nevertheless a slight decrease in erythrocyte glutathione peroxidase activity was noted. Trace elements and antioxidant enzymes in liver homogenates remained unchanged. Oestrone treatment also had no effect on plasma and liver lipid peroxides. The immune response was evaluated by measuring NK activity of splenocytes against 51Cr labelled YAC-I target cells. A 35.5% decrease in the NK activity (p<0.001) was observed after oestrone treatment and may be responsible for graft tolerance. However, the results of these experiments seem to exclude the role of oxidative stress in the modulation of NK activity.

Animals↗
PubMedDate not supplied

[Dose adaptation during training of intracavernous self-injections of prostaglandin E1].

OBJECTIVE: Dose adaptation in self-administered intracavernous PGE1 injections is poorly defined in learning protocols and its degree of difficulty depends on the aetiology of the erectile dysfunction. The authors tried to standardize this phase by studying the results and complications of a protocol using an identical initial dose of PGE1 regardless of the aetiology of erectile dysfunction. MATERIAL AND METHODS: 101 patients consulting for erectile dysfunction participated in a learning protocol of self-administered intracavernous PGE1 injections, consisting of 3 injections systematically starting with 10 micrograms of PGE1, following assessment of the aetiology. RESULTS: For an efficacy of 58.4%, 79.2% and 88.1% after one, two or three injections, respectively, the prolonged erection rate (> or = 6 hours) was 2.7% after the first injection and 0% after the other injections. However, erection durations of 2 to 6 hours have frequently been reported in neurological patients. Discontinuations during the learning phase were only observed in patients presenting with tumescence without rigidity after one injection (5.4%) or two injections (21%). CONCLUSION: In the light of these results and to minimize prolonged erections and discontinuations, while ensuring efficacy, PGE1 dose adaptation can be simply performed by starting with 10 micrograms in all patients except for neurogenic patients (5 micrograms) with an increase to 20 or 30 micrograms in the case of failure.

Adult↗