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An in vitro model of immediate pigment darkening and its activity towards lipid peroxydation induced by an azo compound
Posters - Phorodermatology Day skin at day 3.4 and 5, using UVA doses of 3,5 and 8 times the unprotected MPD value. The sunscreens can be ranked according to three levels of protection. First, two formula of the short UVA filter reinforced line, protected respectively 100% and 50% of the volunteers following 3 and 8 MPD irradiation doses. Second, the third formula belonging to the same line protected 100% of the subjects after 3 MPD and 50% after 8 MPD. Third, the two others sunscreens, based on different UVA filtering systems, protected 50 to 90% and 0 to 10% following respectively 3 and 8 MPD UVA doses. These results clearly showed that a broad spectrum UVA filtration reinforced in the short UVA domain offers a more efficient protection against phototoxicity Benzoyl Peroxyde and Clhorpromazine, even in conditions of very high UVA exposure. I P573 Prevention of solar urticaria using a
broadspectrum sunscreen and determination of a solar urticaria protecting factor (SUPF)
J.L. Peyron’, D. Moyalz, A. Rougie?, C. Hourseau2. ‘Departement of Dermatology, Saint Eloi Hospital, Montpellier; 21’Ort!al Reseamh, Clichy; 3Ln Roche-Posay Pharmaceutical Laboratories, Courbevoie, France Solar urticaria (SU) is a rare photodermatose whose preventive treatment remains difficult. An alternative would the use sunscreens products. Unfortunately, up to now, most them were found poorly effective as SU is known to be ellicited mainly in the UVA. In this study we determine the Solar Urticaria Protection Factor (SUPF) using a broadspectrum sunscreen (SPF (UVB) = 60; IPD/PPD (UVA) = 55/12). 10 patients were investigated. SU was determined in each patient following irradiation with a xenon arc solar simulator (Dermolum UM. W., Germany) equiped with a grating monochromator. The following wavelenghts were used: 360 nm (long UVA), 335 nm (short UVA), 310 (UVB). The Minimal Urticarial Dose (MUD) was assessed for each patient in his triggering spectral band. SUPF was then determined after topical application of the sunscreen formulation or its vehicle according to an arythmetical ratio of 2 MUD. Clinical assessment of erythema and swelling was performed in the early minutes following each irradiation dose. 6 patients responded to UVA, 1 to UVB and 3 to UVA + UVB. The MUD ranged from 80 mJ to 1 J/cm2 in the long UVA, from 40 mJ to 2 J/cm2 in the short UVA and from 40 to 60 m J/cm* in the UVB. The SUPF of the vehicle ranged from 2 to 4, werheas that of the sunscreen formulation reached respectively 90 and 50 in the long UVA and in the short UVA, and 133 in the UVB. These results demonstrate that SU can be effectively prevented when using a highly protective UVB and UVA sunscreen.
IP574
S321
Reduced reactivity of skin prick test after ultraviolet B irradiation
E. Vocks, K. Stander, J. Rakoski, J. Ring. Dept. of Dermatology, Techn. University Munich, Germany The aim of the investigation was to study the influence of ultraviolet B (UVB) irradiation on skin prick test (SPT) reactivity. Method: Atopic volunteers (n = 21) without atopic eczema were prick tested with birch, grass pollen or house dust mite corresponding to individual sensitization using commercial allergen solutions (undiluted, diluted 1:lO and 1:lOO). For WB irradiation subjects were divided in two groups: Group A (n = 8) received local UVB irradiation of the prick test area [e local UV effect], group B (n = 13) received whole body UVB irradiation covering the prick test area [e systemic W effect]. UVB dosage regimen: 3 suberythematous irradiations on 3 consecutive days (mean doses: single: 0.11 J/cm*, cumulative: 0.33 J/cm*, source: Waldmann UV6/UV21). SPT was performed: (1) before, (2) 24 hrs after one and (3) 24 hrs after three WB irradiations. Results: In SPT with diluted allergen solutions weal reactions (ratio allergen/histamine weal size) were significantly decreased by 28% (1: 10 dilution) and 45% (1: 100 dil.) after one suberythematous local UVB irradiation of the prick test area (p = 0.01 resp. 0.02). Comment: The results confirm a short term suppressive effect of UVB radiation on SPT allergen reactions. Possible mechanisms could be due to direct UV effect on mastcells. Conclusion: UV irradiation including even an unique sunbath prior to skin testing might reduce SPT validity. I P575 An in vitro model of immediate pigment
darkening and its activity towards lipid peroxydation induced by an azo compound
C. Routaboul’, S. Fery-Forgues*, A. Lattes*, A. Denis’, A. Vinche’ . ‘Bioderma, 69447 Lyon cedex 3; * UniversitP P. Sabatier 31062 Toulouse cedtx, France In vivo inhibition of immediate pigment darkening (IPD) is commonly used to determine the UVA sun protecting factors of cosmetic preparations. But little information is available concerning this phenomenon. As melanin oxidation is thought to participate, we tried to reproduce WA induced spectroscopic changes in an in vita, system using melanogenic compounds: DOPA (soluble) and pheomelanin (UVA absorbant). WA irradiation of solutions of DOPA and pheomelanin (ratio 190/l) induce an increase in the solution absorbance, with a maximum at 480 nm, inhibited in absence of oxygen and partially reversible, just as IPD do in vivo. Involved radical reactions are discussed. Introduction of irradiated model solutions in lipid suspension prevent their peroxidation up to 95% for 0.3 mM DOPA et 1.6 PM pheomelanin. DOPA and pheomelanins are present at any time subject with whatever phototype, thus the process described in vitro should occur in vivo. This confirms the involvement of melanin precursors in IPD suggested by different authors and provide useful tool for IPD studies.
broadspectrum sunscreen and determination of a solar urticaria protecting factor (SUPF)
J.L. Peyron’, D. Moyalz, A. Rougie?, C. Hourseau2. ‘Departement of Dermatology, Saint Eloi Hospital, Montpellier; 21’Ort!al Reseamh, Clichy; 3Ln Roche-Posay Pharmaceutical Laboratories, Courbevoie, France Solar urticaria (SU) is a rare photodermatose whose preventive treatment remains difficult. An alternative would the use sunscreens products. Unfortunately, up to now, most them were found poorly effective as SU is known to be ellicited mainly in the UVA. In this study we determine the Solar Urticaria Protection Factor (SUPF) using a broadspectrum sunscreen (SPF (UVB) = 60; IPD/PPD (UVA) = 55/12). 10 patients were investigated. SU was determined in each patient following irradiation with a xenon arc solar simulator (Dermolum UM. W., Germany) equiped with a grating monochromator. The following wavelenghts were used: 360 nm (long UVA), 335 nm (short UVA), 310 (UVB). The Minimal Urticarial Dose (MUD) was assessed for each patient in his triggering spectral band. SUPF was then determined after topical application of the sunscreen formulation or its vehicle according to an arythmetical ratio of 2 MUD. Clinical assessment of erythema and swelling was performed in the early minutes following each irradiation dose. 6 patients responded to UVA, 1 to UVB and 3 to UVA + UVB. The MUD ranged from 80 mJ to 1 J/cm2 in the long UVA, from 40 mJ to 2 J/cm2 in the short UVA and from 40 to 60 m J/cm* in the UVB. The SUPF of the vehicle ranged from 2 to 4, werheas that of the sunscreen formulation reached respectively 90 and 50 in the long UVA and in the short UVA, and 133 in the UVB. These results demonstrate that SU can be effectively prevented when using a highly protective UVB and UVA sunscreen.
IP574
S321
Reduced reactivity of skin prick test after ultraviolet B irradiation
E. Vocks, K. Stander, J. Rakoski, J. Ring. Dept. of Dermatology, Techn. University Munich, Germany The aim of the investigation was to study the influence of ultraviolet B (UVB) irradiation on skin prick test (SPT) reactivity. Method: Atopic volunteers (n = 21) without atopic eczema were prick tested with birch, grass pollen or house dust mite corresponding to individual sensitization using commercial allergen solutions (undiluted, diluted 1:lO and 1:lOO). For WB irradiation subjects were divided in two groups: Group A (n = 8) received local UVB irradiation of the prick test area [e local UV effect], group B (n = 13) received whole body UVB irradiation covering the prick test area [e systemic W effect]. UVB dosage regimen: 3 suberythematous irradiations on 3 consecutive days (mean doses: single: 0.11 J/cm*, cumulative: 0.33 J/cm*, source: Waldmann UV6/UV21). SPT was performed: (1) before, (2) 24 hrs after one and (3) 24 hrs after three WB irradiations. Results: In SPT with diluted allergen solutions weal reactions (ratio allergen/histamine weal size) were significantly decreased by 28% (1: 10 dilution) and 45% (1: 100 dil.) after one suberythematous local UVB irradiation of the prick test area (p = 0.01 resp. 0.02). Comment: The results confirm a short term suppressive effect of UVB radiation on SPT allergen reactions. Possible mechanisms could be due to direct UV effect on mastcells. Conclusion: UV irradiation including even an unique sunbath prior to skin testing might reduce SPT validity. I P575 An in vitro model of immediate pigment
darkening and its activity towards lipid peroxydation induced by an azo compound
C. Routaboul’, S. Fery-Forgues*, A. Lattes*, A. Denis’, A. Vinche’ . ‘Bioderma, 69447 Lyon cedex 3; * UniversitP P. Sabatier 31062 Toulouse cedtx, France In vivo inhibition of immediate pigment darkening (IPD) is commonly used to determine the UVA sun protecting factors of cosmetic preparations. But little information is available concerning this phenomenon. As melanin oxidation is thought to participate, we tried to reproduce WA induced spectroscopic changes in an in vita, system using melanogenic compounds: DOPA (soluble) and pheomelanin (UVA absorbant). WA irradiation of solutions of DOPA and pheomelanin (ratio 190/l) induce an increase in the solution absorbance, with a maximum at 480 nm, inhibited in absence of oxygen and partially reversible, just as IPD do in vivo. Involved radical reactions are discussed. Introduction of irradiated model solutions in lipid suspension prevent their peroxidation up to 95% for 0.3 mM DOPA et 1.6 PM pheomelanin. DOPA and pheomelanins are present at any time subject with whatever phototype, thus the process described in vitro should occur in vivo. This confirms the involvement of melanin precursors in IPD suggested by different authors and provide useful tool for IPD studies.