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Biomedical subjects

M C Poelman

Publications and source records attributed to M C Poelman.

16 recordsLinked to original sources
PubMed1998

Correlation between percutaneous penetration of methyl nicotinate and sensitive skin, using laser Doppler imaging.

Cutaneous penetration of methyl nicotinate has been investigated in 20 women divided into reactors and non-reactors on the basis of response to 10% aqueous solution of lactic acid. The vasodilation induced was measured using a laser Doppler perfusion imager (LDPI) every 5 min for 1 h after application of methyl nicotinate. The intensity and duration of inflammation generated by methyl nicotinate were used to assess penetration of this chemical in persons with sensitive skin compared to those with normal skin. Significant differences were found between reactors and non-reactors. Reactors showed a significantly increased intensity of response to methyl nicotinate as early as 5 min after application, and for 30 min afterwards, though the duration of inflammation in these 2 groups was the same. Correlation between increased penetration of methyl nicotinate and skin response to lactic acid may suggest increased penetration of water-soluble chemicals in individuals with sensitive skin.

Administration, Cutaneous↗
PubMed1997

pH measurements during lactic acid stinging test in normal and sensitive skin.

Because of the lack of objective signs, the phenomenon of sensitive skin is hard to document. The measurement of the skin pH variations in the nasolabial fold, and on the forearm, after a single application of lactic acid on a preselected sensitive skin population, versus a control one, is proposed as a useful test to detect this kind of population.

Adult↗
PubMed1995

Scavenger effect of vitamin E and derivatives on free radicals generated by photoirradiated pheomelanin.

The free radical scavenger properties of vitamin E (DL-alpha-tocopherol), a natural antioxidant, and derivatives were studied using an original in vitro method consisting of free radical production by photoirradiation of pheomelanin and direct detection of the free radicals by a physical, specific technique, electron spin resonance. Validation of this method has been realized using well-known biological free radical scavengers, superoxide dismutase and reduced glutathione. DL-alpha-Tocopherol, tocopheryl acetate, tocopheryl linoleate, and tocopheryl polyoxyethylene (POE) succinate induced a significant diminution of the free radical production. In order of efficiency, tocopheryl POE succinate was the best scavenger (37.6% inhibition at 0.25%) followed by tocopheryl linoleate (25.6% inhibition at 1%) and tocopheryl acetate (23.9% inhibition at 0.5%) and finally DL-alpha-tocopherol (16.2% inhibition at 0.05%). The results reported a decrease of the inhibitory effect for high concentrations of DL-alpha-tocopherol (0.1%) and tocopheryl acetate (1%), showing a tendency of this compound to act as a prooxidant. Used in optimal concentrations in cosmetologic or dermatologic formulations, Vitamin E and these derivatives should prevent or reduce the harmful activity of free radicals in the skin.

Animals↗
PubMed1992

Toxic effects and detection of oxygen free radicals on cultured articular chondrocytes generated by menadione.

The aim of this work was to study the proliferation pathological perturbations of cultured chondrocytes in response to menadione, an oxygen free radicals producing drug. Rabbit articular chondrocytes in monolayer culture were treated with 10(-5) M, 1.5.10(-5) M and 2.10(-5) M of menadione during three days. A dose dependent decrease of the proliferative capacity was observed. Flow cytometry analysis revealed a perturbation of the cell cycle progression consisting in an accumulation of cells in the S and G2 + M phases. This growth perturbation was due to oxygen radicals production since a treatment with catalase suppressed these toxic effects. Furthermore, to identify oxygen derived radicals in the cellular suspension of cultures treated with menadione, we used a technique of spin-trapping coupled with electron spin resonance (ESR). The ESR signal corresponding to the DMPO hydroxyl radical adduct (DMPO-OH) has been detected. The spectra observation indicated the actual production of hydroxyl radical. However, superoxide anions have not been identified; this fact can be explained by the low reactivity of these anions with DMPO and by the decomposition of signal DMPO-OOH to DMPO-OH.

Animals↗
PubMed1989

Assessment of topical non-steroidal anti-inflammatory drugs.

A new non-invasive technique for assessing the efficacy of topical non-steroidal anti-inflammatory drugs (NSAID) in man is proposed. The NSAID are initially applied to the skin under occlusion before inflammation is induced by a methyl nicotinate solution. The inflammatory response is quantified in terms of cutaneous blood flow by a laser Doppler velocimeter (LDV). The efficacy of NSAID preparations is calculated by comparing the responses of the LDV to the methyl nicotinate challenge on the pretreated and the non-treated skin sites. This protocol has been used to investigate the effect of three different NSAID preparations (indomethacin, niflumic acid, palmitoyl collagenic acid) and the influence of the vehicle on the efficacy of indomethacin. The three preparations tested gave positive results but with different amplitudes in response. The efficacy of indomethacin varied with the vehicle used.

Administration, Topical↗
PubMed1988

Are corneocytes elastic?

By using a microhandling system, we have recorded the force necessary to elongate isolated corneocytes. According to certain hypothesis, it appears that the elastic modulus of corneocyte is far higher than that of stratum corneum itself. Aggregates of corneocytes are disassembled by forces with a wide range of intensity. In the light of these experiments, stratum corneum appears as a very supple material where the deformations occur more by a plastification of the intercellular medium and an unfolding of the microrelief lines than an elongation of the corneocytes themselves. Moreover, desmosomes remnants could play a certain role in the corneocytes cohesiveness.

Cell Adhesion↗
PubMed1985

New experimental approach to measure the skin-reflected light. Application to cutaneous erythema and blanching.

By modifying the blood supply in the upper part of the dermis, the colour of the skin is changed by any material in contact with it. This is a great difficulty when we want to measure the colour intensity in erythema or blanching. To avoid this problem, we designed and built a device which measures the skin reflectance value without any contact with the skin. The use of this device on man to study the skin blanching after application of dermocorticoids allows us to determine the more potent drug among a series (clobetasol propionate) and, for a given drug (betamethasone), the more efficient preparation (oil-in-water emulsion). The study of the effect of increasing irradiation doses of ultraviolet light show that the sensitivity of the device is equivalent to that of the clinical assessment and that the relationship between the irradiation dose and the skin reflectance is sigmoidal.

Betamethasone Valerate↗
PubMed1984

Objective determination of the bioavailability of dermocorticoids--influence of the formulation.

In order to quantify the intensity of skin blanching and thus predict the bioavailability of topical corticoids, a physical device allowing the measurement of light reflected from skin without any contact between the probe and the skin was used (Leveque et al., 1984). Three series of experiments were carried out: firstly, to assess the vasoconstrictor potency of four corticoids; secondly, to show the influence of the vehicle on the bioavailability of the same drug under various galenic forms, such as fatty ointments or water in oil (W/O) and oil in water (O/W) creams; thirdly, to determine the reservoir effects, if any, of some of these formulations. The results confirm previous findings about the potency of hydrocortisone acetate, triamcinolone 17-acetonide, betamethasone 17-valerate, diflucortolone valerate and clobetasol 17-propionate.

Administration, Topical↗