Comparison of cytotoxicity of various surfactants tested on normal human fibroblast cultures using the neutral red test, MTT assay and LDH release.

We used the neutral red test, MTT assay and lactate dehydrogenase (LDH) release to compare the potential cytotoxicity of six surfactants belonging to different classes--three non-ionic surfactants (Triton x100, octylphenoxypolyethoxy alcohol, from Orion; Tween 60, polyoxyethylene (20) sorbitan monostearate, from ICI Speciality Chemicals; Tween 80, polyoxyethylene (20) sorbitan monolaurate, from Labosi), two anionic surfactants (Texapon K1298, sodium lauryl sulphate, from Henkel; Texapon N40, sodium laurylether sulphate, from Henkel) and one cationic surfactant (benzethonium chloride, from Siber Hegner)--on human fibroblast cultures. According to the LC50 (microg ml(-1)), the tested surfactants can be classified in the following order of increasing cytotoxicity: Tween 80 < Texapon N40 < Tween 60 < Texapon K1298 < Triton x100 < benzethonium chloride.

In vitro correlation between two colorimetric assays and the pyruvic acid consumption by fibroblasts cultured to determine the sodium laurylsulfate cytotoxicity.

The target of this research was to determine the cytotoxicity of sodium laurylsulfate on single-layer cultures of human fibroblasts, using two colorimetric methods (neutral red and MTT tests) and the evaluation of the pyruvic acid consumption by the cells. For the determination of the cytotoxicity by colorimetric tests, we have determined the absorbance at 540 nm using a spectrophotometer. Pyruvic acid, present in the culture medium, is the mitochondria's C3 energetic metabolite. So, a measure of the cell's consumption of pyruvic acid was developed. The reaction is as follows: Pyruvic acid + NADH --> Lactic acid + NAD+ and the enzyme employed is the LDH (lactate dehydrogenase). This method can be used to measure cytotoxicity, proliferation, and the cell's activation. The method is rapid, precise, and lacks any toxic byproduct. The absorbance was measured using a spectrophotometer at 340 nm. The consumption of pyruvic acid follows upon the fibroblast's growth. Sodium laurylsulfate cytotoxicity test after 24 h shows that the NR colorimetric test and the pyruvic acid consumption are correctly correlated (r = 0.91, alpha = 0.05). This dosage can be used to study the barrier properties of the corneocyte layer without destroying the artificial skin.

[Determination of physicochemical characteristics and evaluation of decontaminating efficacy and in vitro safety of cleaning products for contact lenses]. / Détermination des caractéristiques physicochimiques et evaluation de l'efficacité décontaminante et de l'innocuité in vitro de produits d'entretien pour lentilles de contact.

PURPOSE: This work aims to characterize products designed for cleaning contact lenses and particularly their physicochemical properties, their efficiency and their ocular irritancy potential compared to the main requirements of eye-washes. MATERIAL AND METHODS: The physicochemical controls include pH determination, viscosity and freezing point depression. In addition, we carried out the hydrogen peroxide assay for products containing this active substance. A microbiological control was performed when opening the product and after simulation of a 21-day aging. We determined the decontaminating efficacy of the products on four bacterial strains and a fungal strain. Finally, we tested their ocular allowance by an in vitro test. RESULTS: The pH values obtained ranged from 3.2 (oxygenated water solutions) to 7.6. The viscosity was close to a water solution one (about 1 centipoise). The different assays showed hydrogen peroxide content similar to that stated on the package: rate averaged to 3% and was negligible after neutralization. At opening and after simulation the bacteriological quality was excellent. Finally, decontaminating efficiency against germs was very good for the products tested. The products were classified as non-irritant by the ocular irritancy test. CONCLUSION: The results obtained show that the products tested met the reference criteria, particularly eye-wash criteria.

[Characteristics, stability and in vitro efficacy of cleaning products for contact lenses]. / Caractéristiques, stabilité et efficacité in vitro de produits destinés à l'entretien des lentilles de contact.

OBJECTIVE OF THE STUDY: We characterized some market products designed for cleaning contact lenses and we compared their properties to the main requirements of eye-washes. MATERIAL AND METHODS: We performed several physicochemical controls including pH determination, viscosity with a Baume apparatus and the decreasing of the freezing point following the method described by the French Pharmacopea. In addition, we carried out certain analytical controls, concerning three active principles (thiomersal, chlorhexidin digluconate, hydrogen peroxide), at the opening of the different package and after accelerated aging. A microbiological control was performed when opening the product and after a simulation of a 5-day aging. We finally determined the efficacy of the products on four bacterial strains for tests and of deproteinizing products on artificial dust. RESULTS: The pH values obtained ranged from 4.0 (oxygenated water solutions) to 7.8. The viscosity was close to a water solution one. Contents in active substances were usually similar to those stated on the package. At opening, the bacteriological quality was excellent. But, the multidose package were highly contaminated when used. Finally decontaminating efficacy against some germs was very good for the products tested. CONCLUSION: The results obtained show that the rincing products best answer the eye-wash criteria taken as references. Their main disadvantage is their contamination in the case of multidose packaging.

Microbiological study of lyophilized dairy kefir.

Preservation of the intrinsic inhibitory power of dairy kefir after lyophilization by testing several desiccation substrates and several regeneration media was studied. The tested cryoprotectors were ribitol, sodium glutamate and glycerol. After lyophilization, the pellets of kefir were regenerated in water or milk. Glycerol was the best cryoprotector because of its high efficiency and its low cost, white sodium glutamate was unsatisfactory.

Cytotoxicity tests of antibacterial agents on human fibroblasts cultures.

The authors tried to determine and compare the cytotoxicity of several primary substances used in cosmetic or pharmaceutic industry as antimicrobial agents, on single-layer cultures of human fibroblasts. The cytotoxic effect of Germall 115*, Kathon CG* and Pentonium* was pointed out using the colorimetric method with MTT (3-[4-5-dimethyl thiazol 2-yl]-2,5 diphenyl tetrazolium bromide). For each one of these substances, we tested different concentrations with variable contact times. These trials allowed us to classify these products by increasing toxicity as follows: Kathon CG* and Pentonium*. In our experimental conditions, Germall 115* was not cytotoxic.

Evaluation de l'activité antifongique de deux dérivés et test d'innocuitéin vivo de shampooings à visée antipelliculaire ainsi formulés.

Synopsis Two thirds of the population suffer more or less severely from dandruff, a dermatological disease associated with the yeast Pityrosporum ovale. This paper demonstrates the anti-fungal activity of two substances commonly used in hair cosmetics: zinc pyrithione and piroctone olamine, at several concentrations. Based on an optimum concentration, two shampoos were formulated in order to determine the cutaneous tolerance of the finished cosmetics. A profilometry study was carried out using negative impressions obtained from skin prints to calculate the cutaneous tolerance. This study revealed the superiority of the piroctone olamine as an anti-fungal substance and its cutaneous tolerance was also better.