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Protection Factor (protection + factor)
Kinds of Protection Factor Selected AbstractsA novel approach to excellent UV protecting cotton fabric with functionalized MWNT containing water vapor permeable PU coatingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007S. Mondal Abstract This research paper presented a novel approach of developing excellent protection from ultraviolet (UV) radiation of cotton fabrics by means of water vapor permeable (WVP) coatings containing multiwall carbon nanotube (MWNT), a stable and strongly UV absorbing species. The WVP of MWNT containing UV protective coatings of the present development are formed from solution polymer of hydrophilic polyurethane (HPU). MWNTs were dispersed in HPU solution by functionalization of MWNT. The nanotube containing HPU coating shows excellent protection against UV radiation, with only 1 wt % of MWNT (calculated based on solid content of the polymer), a UV Protection Factor (UPF) of 174 and with 2.5 wt % of MWNT a UPF of 421 was obtained, which stated excellent protection (UPF ,50) according to the Australian/New Zealand standards. Scanning electron micrographs of coated fabrics surface showed a film like polymer coating, confirming the fabric surface was successfully coated by polyurethane. The coated fabrics would maintain very good water vapor permeability, hence confirmed the wearing comfort. Room temperature (20,23°C) range soft segment crystal melting of HPU enhances the permeability of coated fabrics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3370,3376, 2007 [source] Determination of Wavelength-Specific UV Protection Factors of Sunscreens in Intact Skin by EPR Measurement of UV-Induced Reactive Melanin RadicalPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Leslie Lund ABSTRACT There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus. We show that we are able to use this assay to determine the monochromatic protection factors (mPF) of research and commercial sunscreens at specific narrow wavebands of UVB, UVA and blue visible light. Both commercial sunscreens, a sun protection factor (SPF) 4 and an SPF 30 product, had mPFs in the UVB range that correlated well with their claimed SPF. However, their mPF in the UVA ranges were only about one-third of claimed SPF. This technique can be used to design and assay sunscreens with optimally balanced UVA and UVB protection. [source] 4% hydroquinone versus 4% hydroquinone, 0.05% dexamethasone and 0.05% tretinoin in the treatment of melasma: a comparative studyINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 7 2005Reyhaneh Astaneh PharmD A randomized, controlled, double-blind clinical study was conducted on 64 patients (phototypes III to V) with melasma, in order to compare 4% hydroquinone cream with a combination product, containing 4% hydroquinone, 0.05% tretinoin and 0.05% dexamethasone, that can be applied as a single cream. The aim of this study was to determine whether hydroquinone provides additional improvement when combined with tretinoin and dexamethasone. Patients were randomly divided into two groups of 32 individuals. One group received 4% hydroquinone (group A) in a cream base. The other received a cream that contains 4% hydroquinone, 0.05% tretinoin and 0.05% dexamethasone (group B). The creams were applied once daily at night and a broad spectrum sunscreen (sun protection factor 15) was used every morning. Patients were evaluated by a clinical investigator subjectively at baseline and after 4, 8 and 12 weeks of therapy. At the baseline visit, the history of melasma, such as duration of disease, patient's age, type of melasma, distribution of melasma, family history, association with pregnancy, sun exposure, genetic factors and oral contraceptive consumption, was taken. Improvement was determined subjectively compared with baseline, on a three-point scale as follows: worse, same and improved (excellent, good, moderate and slight). Descriptive statistics (the ,2 test) were used to report the characteristics of the patients in the two groups. [source] The European standard for sun-protective clothing: EN 13758JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 2 2006T Gambichler Abstract Clothing is considered one of the most important tools for sun protection. Contrary to popular opinion, however, some summer fabrics provide insufficient ultraviolet (UV) protection. The European Committee for Standardization (CEN), has developed a new standard on requirements for test methods and labelling of sun-protective garments. This document has now been completed and is published. Within CEN, a working group, CEN/TC 248 WG14 ,UV protective clothing', was set up with the mission to produce standards on the UV-protective properties of textile materials. This working group started its activities in 1998 and included 30 experts (dermatologists, physicists, textile technologists, fabric manufacturers and retailers of apparel textiles) from 11 European member states. Within this working group, all medical, ethical, technical and economical aspects of standardization of UV-protective clothing were discussed on the basis of the expertise of each member and in consideration of the relevant literature in this field. Decisions were made in consensus. The first part of the standard (EN 13758-1) deals with all details of test methods (e.g. spectrophotometric measurements) for textile materials and part 2 (EN 13758-2) covers classification and marking of apparel textiles. UV-protective cloths for which compliance with this standard is claimed must fulfill all stringent instructions of testing, classification and marking, including a UV protection factor (UPF) larger than 40 (UPF 40+), average UVA transmission lower than 5%, and design requirements as specified in part 2 of the standard. A pictogram, which is marked with the number of the standard EN 13758-2 and the UPF of 40+, shall be attached to the garment if it is in compliance with the standard. The dermatology community should take cognizance of this new standard document. Garment manufacturers and retailers may now follow these official guidelines for testing and labelling of UV-protective summer clothes, and the sun-aware consumer can easily recognize garments that definitely provide sufficient UV protection. [source] In Vitro Sunscreen Transmittance Measurement with Concomitant Evaluation of Photostability: Evolution of a MethodPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Robert M. Sayre The recent paper by Miura et al. (Photochem. Photobiol. 84[6], 1569,1575) offers a re-examination of extant in vitro methods for dynamically measuring sunscreen photodegradation under continuous irradiation in situ. We commend the authors' efforts toward developing an improved system for accurate in vitro sunscreen assessment. This work describes an alternate derivative apparatus incorporating an improved detector which may prove an exceptionally valuable contribution toward that goal. Unfortunately their report suffers from insufficient detail in instrumentation description and lacks requisite calibration procedures. Their utilization of a solar simulator filtered for conventional in vivo sun protection factor (SPF) testing poses transmittance measurement limitations at short wavelengths that are not adequately addressed and is also deficient, relative to sunlight, in longer UVA wavelengths shown to contribute to sunscreen photoinstability. We concur that the in vitro sunscreen testing should utilize continuous or multiple irradiation doses and should ideally use the same 2 mg cm,2 product application amount as does the human SPF test. We encourage their proposal that methodology, which simultaneously measures sunscreen spectral transmittance and photodegradation under continuous irradiation to an accumulated erythemic endpoint, as we previously described, be developed into a consensus test standard. [source] Determination of Wavelength-Specific UV Protection Factors of Sunscreens in Intact Skin by EPR Measurement of UV-Induced Reactive Melanin RadicalPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Leslie Lund ABSTRACT There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus. We show that we are able to use this assay to determine the monochromatic protection factors (mPF) of research and commercial sunscreens at specific narrow wavebands of UVB, UVA and blue visible light. Both commercial sunscreens, a sun protection factor (SPF) 4 and an SPF 30 product, had mPFs in the UVB range that correlated well with their claimed SPF. However, their mPF in the UVA ranges were only about one-third of claimed SPF. This technique can be used to design and assay sunscreens with optimally balanced UVA and UVB protection. [source] Sunscreens: expectation and realizationPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2009Brian Diffey Background: The technical performance of sunscreens has improved dramatically over the past 20 years, so have we now succeeded in delivering protection that meets consumers' expectations? Methods: From a public health perspective, the desire to prevent sunburn and protect against skin cancer are the two major drivers for using sunscreen. This review examines how well consumers can expect to realize these expectations. Results: Sunscreens are used regularly by a minority of people, even during recreational summer exposure. The failure of sunscreen to prevent sunburn is almost always due to the way that sunscreens are applied rather than technical failure of the product. The mismatch between the labelled protection (sun protection factor) and that delivered in practice is a contributory factor to this ,failure'. Sunscreens have been shown to be effective in reducing the incidence of squamous cell cancer and with promising benefits for basal cell cancer. However, the evidence that they are effective in melanoma remains lacking. Conclusion: The formulation and extinction of sunscreens have undoubtedly improved over recent years. Yet the notion that sunscreens provide unequivocal protection against the deleterious effects of sun exposure by everyone who uses them remains elusive. [source] The influence of the amount of sunscreen applied and its sun protection factor (SPF): evaluation of two sunscreens including the same ingredients at different concentrationsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2009Sergio Schalka Background: To estimate labeled sun protection factor (SPF) for sunscreen, the amount of product applied on volunteers, according to food and drug administration (FDA) and International protocols, is 2 mg/cm2. However, different studies have shown that consumers actually apply much less product when exposed to the sun. Previous studies have reported contradictory findings in an attempt to correlate the amount applied in relation to SPF. The objective of the present study was to estimate the influence of the quantity of sunscreen applied in the determination of SPF, according to the FDA methodology. Subjects and methods: Forty volunteers were included in two groups (SPF 15 and 30). The selected sunscreen was then applied in four different quantities (2, 1.5, 1.0 and 0.5 mg/cm2). All areas were irradiated with a solar simulator. After 24 h, the minimal erythemal dose (MED) and SPF were determined. Results: In both groups, we observed that the SPF decreased when the amount of sunscreen applied was decreased. The differences between the 2 mg/cm2 area and the others were significant in both groups (P<0.001). The correlation between specified SPF and applied amount grew exponentially. Conclusion: The protection provided by sunscreen is related to the amount of product applied. It is essential to educate consumers to apply larger amounts of sunscreen for adequate photoprotection. [source] Sunscreens containing the broad-spectrum UVA absorber, Mexoryl® SX, prevent the cutaneous detrimental effects of UV exposure: a review of clinical study resultsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2008Anny Fourtanier Background: UVA exposure of human skin mainly produces reactive oxygen species (ROS) leading to DNA, cell and tissue damage. It alters immune function, pigmentation and it is certainly responsible for a large part of photoaging changes. Moreover UVA is implicated in the etiology of several photodermatoses. As a consequence, to provide adequate protection, sunscreens or skin care products for daily use protective products need UVA absorbers combined with UVB ones. Aim: To assess the efficacy of sunscreens containing a broad-spectrum UVA absorber the Mexoryl® SX or ecamsule and to compare formulations with and without it through a large number of clinical studies in human volunteers and patients. Methods: The following assessments were conducted: ,Prevention of excessive pigmentation induced by UV exposure in Caucasian and Asian skins using a method that measures pigmentation protection factors (PPF). ,Efficacy against DNA damage by measurement of pyrimidine dimer formation and p53 protein accumulation. ,Protection of immune system using delayed type hypersensitivity (DTH) reactions to recall antigens, isomerization of urocanic acid (UCA), alteration of Langerhans cells (LC) density, morphology and function. ,Reduction of epidermal and dermal alterations induced by repeated UVA or UV solar simulated radiation (SSR) using histology or immunohistology. ,Prevention of the polymorphous light eruption (PMLE) in patients prone to develop this disease. Results: Mexoryl® SX-containing formulations showed a dose-dependent level of protection against pigmentation. For a same sun protection factor (SPF) the higher the UVA protection was, the higher was the PPF. Pyrimidine dimer formation and p53 accumulation were significantly reduced by formulations with Mexoryl® SX. In the studies looking at the suppression of DTH reactions to recall antigens by the different UV spectra, the LC alterations and the cis UCA formation, Mexoryl® SX formulations always showed a higher protective potency than sunscreen without it even when the protection against erythema was similar (products with same SPF). Mexoryl® SX formulations also prevented or significantly decreased to minimal, ferritin, tenascin and lysozyme expression induced by repeated UVA or SSR exposure. It also reduced the enhancement of collagenase 2 mRNA expression induced by SSR exposure. Finally PMLE study demonstrated that UVA protection was essential for the prevention of this photodermatose. Conclusion: Mexoryl® SX formulated in sunscreens or daily use products have been shown to be an effective UV absorber, leading to an increased efficacy of these products against a large number of biological damage induced by UVA, SSR or sun exposure. [source] Testing high SPF sunscreens: a demonstration of the accuracy and reproducibility of the results of testing high SPF formulations by two methods and at different testing sitesPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2002Patricia Poh Agin Background/Purpose: The goals of this study were (i) to demonstrate that existing and widely used sun protection factor (SPF) test methodologies can produce accurate and reproducible results for high SPF formulations and (ii) to provide data on the number of test-subjects needed, the variability of the data, and the appropriate exposure increments needed for testing high SPF formulations. Methods: Three high SPF formulations were tested, according to the Food and Drug Administration's (FDA) 1993 tentative final monograph (TFM) ,very water resistant' test method and/or the 1978 proposed monograph ,waterproof' test method, within one laboratory. A fourth high SPF formulation was tested at four independent SPF testing laboratories, using the 1978 waterproof SPF test method. All laboratories utilized xenon arc solar simulators. Results: The data illustrate that the testing conducted within one laboratory, following either the 1978 proposed or the 1993 TFM SPF test method, was able to reproducibly determine the SPFs of the formulations tested, using either the statistical analysis method in the proposed monograph or the statistical method described in the TFM. When one formulation was tested at four different laboratories, the anticipated variation in the data owing to the equipment and other operational differences was minimized through the use of the statistical method described in the 1993 monograph. Conclusions: The data illustrate that either the 1978 proposed monograph SPF test method or the 1993 TFM SPF test method can provide accurate and reproducible results for high SPF formulations. Further, these results can be achieved with panels of 20,25 subjects with an acceptable level of variability. Utilization of the statistical controls from the 1993 sunscreen monograph can help to minimize lab-to-lab variability for well-formulated products. [source] UV-induced immune suppression and sunscreenPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2000E. M. Gil Sun protection factor (SPF) that measures sunscreen protection against erythema and edema may not be enough to measure a sunscreen's activity against many other biologic reactions induced by ultraviolet radiation (UV). It may be better to evaluate sunscreen efficacy using various tools including immune protection factor (IPF), mutation protection factor (MPF) and protection against photocarcinogenesis. In terms of immune protection, sunscreens protected against UV-induced immune suppression significantly. But protection in some cases was partial and often the IPF of sunscreens were less than the SPF. IPF may differ with various immunological endpoints, and it may be better to use a couple of different assays to measure sunscreen protection more objectively. Sunscreen use protects against most UV-induced non-melanoma skin cancers and actinic keratoses but its activity against melanoma is not clear. More studies with broad-spectrum stable sunscreens and better models for the investigation of malignant melanoma are required. [source] Evaluation of efficacy and safety of rucinol serum in patients with melasma: a randomized controlled trialBRITISH JOURNAL OF DERMATOLOGY, Issue 5 2007A. Khemis Summary Background, Melasma is a hyperpigmentation disorder predominantly affecting sun-exposed areas in women, which is often refractory to treatment. Most commercially available treatments incorporate inhibitors of tyrosinase, a key enzyme in melanin production within the melanocyte. In general, however, the efficacy of these therapies is somewhat limited. Recent studies have identified other enzymes that play an important role in melanogenesis, including tyrosinase-related protein-1 (TRP-1), which catalyses the oxidation of the melanogenetic intermediate 5,6-dihydroxyindole-2-carbolylic acid. Rucinol (4- n -butylresorcinol) has been shown to inhibit the activity of both tyrosinase and TRP-1. Objectives, To assess the efficacy of rucinol serum 0·3% vs. the corresponding vehicle as a treatment for melasma. Secondary objectives were to evaluate local and general tolerability and to assess the skin acceptability of rucinol serum in the target population. Methods, In this prospective, single-centre, double-blind, randomized, vehicle-controlled, bilateral (split-face) comparative trial, 32 women with melasma were provided with two identical tubes containing rucinol serum 0·3% or vehicle. The products were each applied to one-half of the face, according to the randomization scheme, twice daily for 12 weeks (phase 1). A broad-spectrum sunscreen (sun protection factor 60) was also applied daily. Assessments at baseline, 4, 8 and 12 weeks included clinical evaluations by a dermatologist, chromametry, ultraviolet and standard photography, and assessments of skin acceptability and tolerability. After 12 weeks, patients were given the option of an additional 3-month treatment period of open full-face rucinol treatment, with reviews at 16, 20 and 24 weeks (phase 2). Results, Twenty-eight patients completed phase 1 and 26 patients completed phase 2. After 12 weeks, the clinical pigmentation score for rucinol-treated skin was significantly lower than for vehicle-treated skin (P = 0·027). During phase 2, rucinol induced a significant reduction in mean pigmentation score on the half of the face previously treated with vehicle. There was also a further, significant improvement on the rucinol-treated side of the face. Chromametry measurements showed that skin was significantly lighter and less yellow, with a strong trend towards reduced redness, following rucinol therapy compared with vehicle. Rucinol serum showed good tolerability and acceptability and was considered to have good or fair efficacy by 78% of the patient population. Conclusions, Rucinol serum was shown to have significant efficacy compared with vehicle alone in improving melasma after 3 months of treatment, according to clinical and objective assessments of skin colour. [source] Sunscreen ingredients and labelling: a survey of products available in the UKCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 4 2007S. Wahie Summary Background., In Europe, where sunscreens are classified as cosmetics, products may contain one or several of 27 permitted ,ultraviolet filters'. We were unable to find published data on the frequency of usage of individual ultraviolet (UV)-absorbing chemicals in currently available sunscreens. Aim., To record the active ingredients and labelling characteristics of sunscreens available in the UK. Methods., In 2005, two dermatologists visited seven retail outlets, which stocked a large range of sunscreens. Manufacturers were also contacted. For each product, the names of UV-protective ingredients and the labelling information, including sun protection factor (SPF), UVA protection and age group for which the product was marketed were recorded. Results., Data on 308 skin sunscreen products and 21 lip sunscreens were recorded. For skin products, the SPF ranged from 2 to 60. In total, 23 different UV-absorbing ingredients were found, 4 of which were found in >,25% of products. The child and baby skin sunscreens (n = 52) had a significantly higher median SPF of 40, compared with 15 for the remaining 256 adult products (P < 0.001). The number of UV-absorbing chemicals and the frequency of those commonly used did not differ substantially between child and adult products. Of skin sunscreens marketed for babies, 60% contained 2,6 UV-absorbing chemicals. Nearly half of the skin sunscreens contained at least one of nine UV-absorbing chemicals not available in patch testing formulations from commercial suppliers. Conclusions., The results of this survey indicate current sunscreen content and labelling, and are a benchmark from which new developments can be tracked. More standard sunscreen labelling, particularly separate listing of active ingredients, would be helpful. It was surprising to find UV-absorbing chemicals in products sold for use on babies. [source] In vitro evaluation of sun protection factors of sunscreen agents using a novel UV spectrophotometric techniqueINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2008M. D. Bleasel Synopsis A method for the in vitro determination of low- and high-value sun protection factors (SPF) of sunscreens using artificial substrates and a novel pseudo double beam (PDB) mode of operation of a standard double beam UV spectrophotometer is described. The method allows transmittance to be calculated from detector responses of reference and sample beams measured at different gain levels and facilitates the accurate quantification of low levels of electromagnetic radiation transmitted through highly absorbing samples. The spectrophotometer was modified to hold quartz diffusing plates on which a substrate [TransporeÔ adhesive tape or human stratum corneum obtained from a skin surface biopsy (SSB)] and the sunscreens to be tested were applied. The PDB mode of operation increased the effective linear range of the detector response of the spectrophotometer by a factor of approximately 20000-fold, enabling the in vitro SPF determination technique to be applied to both high and low SPF value sunscreens. Eight commercial sunscreens with known SPF values ranging from 4 to 77, previously determined by in vivo methods, were tested in vitro using both test substrates and correlations between the in vivo and in vitro values were determined. SPF values determined using the in vitro method correlated well with the known in vivo results (TransporeÔ tape, R2 = 0.611; SSB, R2 = 0.7928). The in vitro SPF obtained for one of the tested products differed substantially from the cited in vivo SPF value. Independent in vitro and in vivo re-evaluation of the SPF of this product matched the value predicted by the present method much more closely than the originally cited in vivo value. All determined SPFs were ordered correctly in comparison to in vivo ranking and the technique appeared to correctly identify a sunscreen that had a labelled SPF value that was significantly higher than its true SPF. Résumé Une méthode destinée à déterminer in vitro les facteurs de protection solaire (SPF) d'écrans solaires de faible et haut indice est décrite. Elle met en ,uvre des substrats artificiels et un nouveau mode opératoire reposant sur l'utilisation du pseudo double faisceau (PDB) d'un spectrophotomètre UV double faisceau standard. La méthode permet le calcul de la transmittence à partir des réponses du détecteur de référence et la mesure en simple faisceau à différents niveaux de gain facilitant ainsi la quantification précise des faibles niveaux de radiation électromagnétique (EMR) transmis à travers des échantillons hautement absorbants. Le spectrophotomètre a été modifié de façon à fixer des plaques diffusantes en quartz sur lesquelles un substrat (ruban adhésif Transport TM ou du stratum corneum humain obtenu à partir de biopsie de surface de peau (SSB) et les écrans solaires testés ont été appliqués. Le mode opératoire PTB augmente la gamme linéaire effective de la réponse du détecteur du spectrophotomètre d'un facteur approximatif 20.000 permettant, à cette technique de détermination des SPF in vitro, d'être appliquée à la fois sur les écrans solaires de haut et bas SPF. Huit écrans solaires commerciaux de SPF connus allant de 4 à 77, préalablement déterminés par des méthodes in vivo, ont été testés in vitro en utilisant les deux substrats, et les corrélations entre les valeurs in vivo et in vitro ont été déterminées. Les valeurs SPF déterminées en utilisant la méthode in vitro est bien corrélée avec les résultats in vivo connus (ruban transport, R2 = 0.611; SSB, R2 = .7928). Le SPF in vitro pour l'un des produits testés diffère fortement des valeurs SPF citées in vivo. Une réévaluation indépendante des SPF in vitro et in vivo de ce produit ajuste la valeur prédite par la présente méthode de façon beaucoup plus proche que la valeur originale citée in vivo. Tous les SPF ainsi déterminés sont ordonnés correctement en comparaison au classement in vivo et la technique semble identifier correctement un écran solaire qui possède un SPF libellé significativement plus haut que son vrai SPF. [source] Photostability of UV Absorber Systems in Sunscreens,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Bernd Herzog Sunscreens are used to protect the human skin against harmful UV radiation. Today there is a trend toward higher sun protection factors (SPF) and better UVA protection. Methods for the assessment of SPF and UVA protection involve irradiation of the product, and the photostability properties of the sunscreen have an influence on its performance. Sunscreens often contain more than one UV filter. Thus it is important to understand the photostability properties of the complete system. The filter combinations used may exhibit destabilizing, stabilizing or inert interactions. For that reason, besides assessment of the properties of the single filters, photostabilities of binary filter combinations are investigated. Destabilization occurs when two UV absorbers undergo a chemical reaction after absorption of UV radiation. Stabilization may be achieved when the optical density of the system is very high, giving rise to a self-protection effect of the sunscreen film. Photounstable UV absorbers may be additionally stabilized by employing triplet quenchers. Being aware of these mechanisms and applying them for specific UV filter combinations can help in designing efficient sunscreens. [source] Determination of Wavelength-Specific UV Protection Factors of Sunscreens in Intact Skin by EPR Measurement of UV-Induced Reactive Melanin RadicalPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Leslie Lund ABSTRACT There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus. We show that we are able to use this assay to determine the monochromatic protection factors (mPF) of research and commercial sunscreens at specific narrow wavebands of UVB, UVA and blue visible light. Both commercial sunscreens, a sun protection factor (SPF) 4 and an SPF 30 product, had mPFs in the UVB range that correlated well with their claimed SPF. However, their mPF in the UVA ranges were only about one-third of claimed SPF. This technique can be used to design and assay sunscreens with optimally balanced UVA and UVB protection. [source] Sunscreens containing the broad-spectrum UVA absorber, Mexoryl® SX, prevent the cutaneous detrimental effects of UV exposure: a review of clinical study resultsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2008Anny Fourtanier Background: UVA exposure of human skin mainly produces reactive oxygen species (ROS) leading to DNA, cell and tissue damage. It alters immune function, pigmentation and it is certainly responsible for a large part of photoaging changes. Moreover UVA is implicated in the etiology of several photodermatoses. As a consequence, to provide adequate protection, sunscreens or skin care products for daily use protective products need UVA absorbers combined with UVB ones. Aim: To assess the efficacy of sunscreens containing a broad-spectrum UVA absorber the Mexoryl® SX or ecamsule and to compare formulations with and without it through a large number of clinical studies in human volunteers and patients. Methods: The following assessments were conducted: ,Prevention of excessive pigmentation induced by UV exposure in Caucasian and Asian skins using a method that measures pigmentation protection factors (PPF). ,Efficacy against DNA damage by measurement of pyrimidine dimer formation and p53 protein accumulation. ,Protection of immune system using delayed type hypersensitivity (DTH) reactions to recall antigens, isomerization of urocanic acid (UCA), alteration of Langerhans cells (LC) density, morphology and function. ,Reduction of epidermal and dermal alterations induced by repeated UVA or UV solar simulated radiation (SSR) using histology or immunohistology. ,Prevention of the polymorphous light eruption (PMLE) in patients prone to develop this disease. Results: Mexoryl® SX-containing formulations showed a dose-dependent level of protection against pigmentation. For a same sun protection factor (SPF) the higher the UVA protection was, the higher was the PPF. Pyrimidine dimer formation and p53 accumulation were significantly reduced by formulations with Mexoryl® SX. In the studies looking at the suppression of DTH reactions to recall antigens by the different UV spectra, the LC alterations and the cis UCA formation, Mexoryl® SX formulations always showed a higher protective potency than sunscreen without it even when the protection against erythema was similar (products with same SPF). Mexoryl® SX formulations also prevented or significantly decreased to minimal, ferritin, tenascin and lysozyme expression induced by repeated UVA or SSR exposure. It also reduced the enhancement of collagenase 2 mRNA expression induced by SSR exposure. Finally PMLE study demonstrated that UVA protection was essential for the prevention of this photodermatose. Conclusion: Mexoryl® SX formulated in sunscreens or daily use products have been shown to be an effective UV absorber, leading to an increased efficacy of these products against a large number of biological damage induced by UVA, SSR or sun exposure. [source] Determination of UVA protection factors using the persistent pigment darkening (PPD) as the end pointPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 6 2000(Part 1) Calibration of the method Background/Aims: The accuracy and reliability of any method to assess the UVA protection effectiveness of sunscreens needs to be demonstrated. The aim of the present study was to calibrate the effectiveness of a biological end point (Persistent Pigment Darkening, PPD) to assess UVA photoprotection. Methods: Persistent Pigment Darkening was selected as the end point because its action spectrum extends across the UVA. A broad UVA source was chosen to challenge all UVA wavelengths. Attenuation of UVA was performed with neutral density filters (equally absorbing at all wavelengths). Human subjects were tested with a series of UVA beams attenuated by the neutral density filters. The UVA protection effectiveness of a standard sunscreen was also tested with four panels of volunteers to assess the reproducibility of the method. Results: The attenuation factors of the neutral density filters were found to correspond to the UVA protection factors arrived at with PPD as the end point. The repetitive tests showed a good internal consistency of the method. Conclusions: The calibration procedure proposed shows threshold PPD, used as an end point in a UVA-PF test method, to be a reliable endogenous dosimeter for UVA radiation that enters the skin. [source] Accumulated p53 protein and UVA protection level of sunscreensPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 1 2000S. Seité Nuclear p53 expression is a sensitive parameter for the detection of ultraviolet (UV)-induced skin damage, and it has been used as an endpoint to evaluate the effectiveness of sunscreens. In this study, we compared the protection provided by two sunscreens having identical sun protection factors (SPF) but different UVA protection factors (UVA-PF) measured by the persistent pigment darkening method (PPD). The SPF of the sunscreens was 7 and the UVA-PF were respectively 7 and 3. Nuclear p53 protein was quantified in human skin biopsies treated with sunscreens and exposed 8 times to 5 MED of solar simulated radiation (SSR). The results showed that both sunscreens offered only partial protection against the increased expression of nuclear p53 protein induced by repetitive SSR exposures. However, a significantly lower level of p53-positive cells was found in areas protected with the sunscreen having the higher UVA-PF compared to the other sunscreen protected areas. In order to verify whether the difference in efficacy of these products was due to the difference in UVA absorption capacity, we quantified epidermal p53 protein accumulation after 8 exposures to either UVA (320,400 nm) or UVA1 (340,400 nm). We showed that as with SSR, repetitive exposures to 12.5 and 25 J/cm2 of UVA or UVA1 induced a significant increase in p53-positive cells in the human epidermis. These results confirmed that SPF determined on the basis of an acute erythemal reaction does not predict the level of protection against cumulative damage. They also showed that the protection provided by two sunscreens with different UVA protection factors is different (based on nuclear p53 protein accumulation), and that the PPD method can distinguish varying levels of sunscreen efficacy against UVA-induced cell damage. [source] Near Infrared Spectroscopy as a Tool for the Determination of Eumelanin in Human HairPIGMENT CELL & MELANOMA RESEARCH, Issue 4 2004Marina Zoccola Eumelanins are brown-black pigments present in the hair and in the epidermis which are acknowledged as protection factors against cell damage caused by ultraviolet radiation. The quantity of eumelanin present in hair has recently been put forward as a means of identifying subjects with a higher risk of skin tumours. For epidemiological studies, chromatographic methods of determining pyrrole-2,3,5-tricarboxylic acid (PTCA; the principal marker of eumelanin) are long, laborious and unsuitable for screening large populations. We suggest near infrared (NIR) spectroscopy as an alternative method of analysing eumelanin in hair samples. PCTA was determined on 93 samples of hair by means of oxidizing with hydrogen peroxide in a basic environment followed by chromatographic separation. The same 93 samples were then subjected to NIR spectrophotometric analysis. The spectra were obtained in reflectance mode on hair samples which had not undergone any preliminary treatment, but had simply been pressed and placed on the measuring window of the spectrophotometer. The PTCA values obtained by means of HPLC were correlated with the near infrared spectrum of the respective samples. A correlation between the PTCA values obtained by means of HPLC and the PTCA values obtained from an analysis of the spectra was obtained using the principal component regression (PCR) algorithm. The correlation obtained has a coefficient of regression (R2) of 0.89 and a standard error of prediction (SEP) of 13.8 for a mean value of 108.6 ng PTCA/mg hair. Some considerations about the accuracy of the obtained correlation and the main sources of error are made and some validation results are shown. [source] Amide proton hydrogen exchange rates for sperm whale myoglobin obtained from 15N- 1H NMR spectraPROTEIN SCIENCE, Issue 1 2000Silvia Cavagnero Abstract The hydrogen exchange behavior of exchangeable protons in proteins can provide important information for understanding the principles of protein structure and function. The positions and exchange rates of the slowly-exchanging amide protons in sperm whale myoglobin have been mapped using 15N- 1H NMR spectroscopy. The slowest-exchanging amide protons are those that are hydrogen bonded in the longest helices, including members of the B, E, and H helices. Significant protection factors were observed also in the A, C, and G helices, and for a few residues in the D and F helices. Knowledge of the identity of slowly-exchanging amide protons forms the basis for the extensive quench-flow kinetic folding experiments that have been performed for myoglobin, and gives insights into the tertiary interactions and dynamics in the protein. [source] Effects of low-dose ultraviolet radiation on in vivo human cutaneous recall responsesAUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 3 2001Diona L Damian SUMMARY Relatively few studies have examined the effects of low-dose ultraviolet (UV) radiation on in vivo human cutaneous immunity, or the ability of sunscreens to prevent UV-induced immunosuppression. We have studied the effects of solar-simulated UV radiation on nickel contact hypersensitivity (CHS) in nickel-allergic volunteers, and on delayed type hypersensitivity responses in Mantoux-positive volunteers. Nickel CHS and Mantoux responses were significantly suppressed by acute, suberythemal UV exposures equivalent to less than 8 min summer sunlight. Both UVA and UVB wavebands were immunosuppressive, but UVA-induced immunosuppression was transient, whereas UVB had a more sustained effect. Dose,responses for UV immunosuppression were determined using the nickel method, enabling calculation of in vivo sunscreen immune protection factors in a manner analogous with sun protection factor measurement. Sunscreens were found to confer significantly less protection against UV-induced immunosuppression than against UV-induced erythema. [source] Glycerol-induced folding of unstructured disulfide-deficient lysozyme into a native-like conformationBIOPOLYMERS, Issue 8 2009Keiko Sakamoto Abstract 2SS[6-127,64-80] variant of lysozyme which has two disulfide bridges, Cys6-Cys127 and Cys64-Cys80, and lacks the other two disulfide bridges, Cys30-Cys115 and Cys76-Cys94, was quite unstructured in water, but a part of the polypeptide chain was gradually frozen into a native-like conformation with increasing glycerol concentration. It was monitored from the protection factors of amide hydrogens against H/D exchange. In solution containing various concentrations of glycerol, H/D exchange reactions were carried out at pH* 3.0 and 4°C. Then, 1H- 15N-HSQC spectra of partially deuterated protein were measured in a quenching buffer for H/D exchange (95% DMSO/5% D2O mixture at pH* 5.5 adjusted with dichloroacetate). In a solution of 10% glycerol, the protection factors were nearly equal to 10 at most of residues. With increasing glycerol concentration, some selected regions were further protected, and their protection factors reached about a 1000 in 30% glycerol solution. The highly protected residues were included in A-, B-, and C-helices and ,3-strand, and especially centered on Ile 55 and Leu 56. In 2SS[6-127,64-80], long-range interactions were recovered due to the preferential hydration by glycerol in the hydrophobic box of the ,-domain. Glycerol-induced recovering of the native-like structure is discussed from the viewpoint of molten globules growing with the protein folding. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 665,675, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Prevalence of allergy, patterns of allergic sensitization and allergy risk factors in rural and urban childrenALLERGY, Issue 9 2007B. Majkowska, Wojciechowska Background:, We aimed to compare the prevalence of allergic diseases and sensitization in children living in urban and rural areas and to identify potential risk/protection factors associated with allergy. Methods:, School children 12,16 years old, from urban community (n = 201) and rural area (n = 203) were recruited. The data obtained by questionnaire were referred to doctors' diagnosis, skin prick tests (SPTs), and serum specific and total IgE assessment. Results:, The prevalence of allergic diseases in urban children was significantly higher as compared with rural children [asthma 16.42%vs 1.97% (P < 0.001) allergic rhinitis 38.81%vs 10.84% (P < 0.001)]. Positive SPTs to at least one allergen was found in 63.7% of urban and 22.7% rural children (P < 0.001). Significantly higher percentage of allergic rural than urban children were monosensitized or sensitized to 2,4 allergens, but almost a fourfold higher percentage of allergic urban children was found to be sensitized to five or more allergens (P < 0.0001). The history of frequent upper respiratory factor (URT) infections, antibiotic therapy, tonsiltectomy/adenoidectomy were positively associated with development of atopy and sensitization. Conclusion:, Our findings confirm that residence of rural area is associated with a significant lower prevalence of allergic sensitization and symptoms in school children. Several risk and protective factors related to environment and style of life could be identified in both environments. [source] | ||||||||||||||||