Home About us Contact
|
Home About us Contact | ||
|
|
||
Photoprotection
Terms modified by Photoprotection Selected AbstractsMolecular response to climate change: temperature dependence of UV-induced DNA damage and repair in the freshwater crustacean Daphnia pulicariaGLOBAL CHANGE BIOLOGY, Issue 4 2004Emily J. MacFadyen Abstract In temperate lakes, asynchronous cycles in surface water temperatures and incident ultraviolet (UV) radiation expose aquatic organisms to damaging UV radiation at different temperatures. The enzyme systems that repair UV-induced DNA damage are temperature dependent, and thus potentially less effective at repairing DNA damage at lower temperatures. This hypothesis was tested by examining the levels of UV-induced DNA damage in the freshwater crustacean Daphnia pulicaria in the presence and absence of longer-wavelength photoreactivating radiation (PRR) that induces photoenzymatic repair (PER) of DNA damage. By exposing both live and dead (freeze-killed) Daphnia as well as raw DNA to UV-B in the presence and absence of PRR, we were able to estimate the relative importance and temperature dependence of PER (light repair), nucleotide excision repair (NER, dark repair), and photoprotection (PP). Total DNA damage increased with increasing temperature. However, the even greater increase in DNA repair rates at higher temperatures led net DNA damage (total DNA damage minus repair) to be greater at lower temperatures. Photoprotection accounted for a much greater proportion of the reduction in DNA damage than did repair. Experiments that looked at survival rates following UV exposure demonstrated that PER increased survival rates. The important implication is that aquatic organisms that depend heavily on DNA repair processes may be less able to survive high UV exposure in low temperature environments. Photoprotection may be more effective under the low temperature, high UV conditions such as are found in early spring or at high elevations. [source] Photoprotection: where do we stand?JOURNAL OF COSMETIC DERMATOLOGY, Issue 4 2006Electra Nicolaidou MD Summary Ultraviolet sun radiation can cause several deleterious effects on the skin, including photoaging and carcinogenesis. Physical protection and sunscreens are currently the two main types of photoprotection. Overall, people seem informed about the dangers of sun exposure, but sometimes they are not willing to implement the right sun-protection measures. Sunscreens are reported to be the most frequently used method worldwide, but they cannot substitute physical protection and a proportion of people do not apply them correctly. Public campaigns, together with fashion and the right role models, can still offer a lot in persuading people to change their habits towards a more sun-protected life. [source] Photoprotection of bacterial-derived melanin against ultraviolet A,induced cell death and its potential application as an active sunscreenJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 7 2008J Geng Abstract Background, The increase in the incidence of non-melanoma skin tumours, photoaging, and immunosuppression demand for more effective sunscreen on ultraviolet A (UVA) irradiation. Objectives, The aim of the study is to evaluate the photoprotective effects of a bacterial-derived melanin against UVA-induced damages in vitro and in vivo. Methods, Human fibroblasts were used to assess the role of the bacterial-derived melanin on cell viability against UVA. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and nuclear morphology were employed to evaluate the photoprotection at the cellular level. Fluorometric assays were performed to detect the formation of reactive oxygen species (ROS) in the cells. Evaluations of the bacterial-derived melanin as a sunscreen were measured by transmission test and persistent pigment darkening on human skin. Results, Bacterial-derived melanin efficiently scavenged ROS in the fibroblasts after UVA irradiation. The cell viability of xeroderma pigmentosum (XP) fibroblast treated with varied doses of melanin increased dramatically in comparison with untreated control and the treated XP fibroblasts became more resistant to UVA-induced apoptosis than normal fibroblasts. Although the relative transmission didn't change too much with different concentration of bacterial-derived melanin, this melanin could keep UVA-irradiated skin from pigment darkening and act as an active sunscreen on skin. Conclusions, The bacterial-derived melanin provided significant protection to fibroblast cell and human skin against the UVA radiation. It has the potential to be developed as an active sunscreen for the patients with photosensitivity skin to sun exposure. [source] Classification of hypotheses on the evolution of autumn coloursOIKOS, Issue 3 2009Marco Archetti I review the hypotheses that have been proposed to explain the adaptive value of autumn leaf colours. The available adaptive hypotheses can be reduced to the following. Photoprotection: pigments protect against photoinhibition or photooxidation allowing a more efficient recovery of nutrients. Drought resistance: pigments decrease osmotic potential allowing leaves to tolerate water stress. Leaf warming: pigments convert light into heat and warm leaves. Fruit flag: colour attracts animals that help disperse seeds. Coevolution: colour signals that the tree is not a suitable host for insects. Camouflage: colour makes leaves less detectable to herbivores. Anticamouflage: colour enhances conspicuousness of parasites dwelling on leaves to predators or parasitoids. Unpalatability: pigments act as direct anti-feedants against herbivores. Reduced nutrient loss: yellow leaves have less to lose against herbivory. Tritrophic mutualism: colour attracts aphids which attract ants that defend the trees from other insects. For each hypothesis I mention the original references, I define assumptions and predictions, and I discuss briefly conceptual problems and available evidence. [source] Photoprotection by Porcine Eumelanin Against Singlet Oxygen Production,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2008Alice Wang Melanin, a major pigment found in retinal pigment epithelium (RPE) cells, is considered to function in dual roles, one protective and one destructive. By quenching free radical species and reactive oxygen species (ROS) melanin counteracts harmful redox stress. However, melanin is also thought to be capable of creating ROS. In this destructive role, melanin increases redox strain in the cell. This study uses readily available eumelanin extracted from porcine RPE cells as a more authentic model than synthetic melanin to determine specific mechanisms of melanin activity with regard to singlet oxygen in the presence and absence of rose bengal, a singlet-oxygen photosensitizer. Optical detection of singlet-oxygen was determined by monitoring the bleaching of p -nitrosodimethylaniline in the presence of histidine. Production of singlet oxygen in aqueous oxygen-saturated solutions of rose bengal without eumelanin was readily accomplished. In contrast, detection of singlet oxygen in oxygen-saturated solutions of eumelanin without rose bengal failed, consistent with results of others. However, a significant decrease in singlet oxygen production by rose bengal was observed in the presence of eumelanin. After correction for light absorption and chemical bleaching of eumelanin, the results show that eumelanin also provides a photoprotective mode arising from chemistry, that is, not just the physical process of light absorption followed by energy dissipation as heat. [source] Photoprotection in Human Skin,A Multifaceted SOS Response,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2008Mark S. Eller Human skin has developed elaborate defense mechanisms for combating a wide variety of potentially damaging environmental factors; principal among these is UV light. Despite these defenses, short-term damage may include painful sunburn and long-term UV damage results in both accelerated skin aging and skin cancers such as basal cell carcinoma, squamous cell carcinoma and even malignant melanoma. While UV radiation damages many cellular constituents, its most lasting effects involve DNA alteration. The following sections briefly review UV-inducible protective responses in bacteria and in skin, thymidine dinucleotides (pTT) as a powerful probe of DNA damage responses, and potential means of harnessing these inducible responses therapeutically to reduce the now enormous burden of cutaneous photodamage in our society. [source] Resveratrol Imparts Photoprotection of Normal Cells and Enhances the Efficacy of Radiation Therapy in Cancer Cells,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2008Shannon Reagan-Shaw Solar radiation spans a whole range of electromagnetic spectrum including UV radiation, which are potentially harmful to normal cells as well as ionizing radiations which are therapeutically beneficial towards the killing of cancer cells. UV radiation is an established cause of a majority of skin cancers as well as precancerous conditions such as actinic keratosis. However, despite efforts to educate people about the use of sunscreens and protective clothing as preventive strategies, the incidence of skin cancer and other skin-related disorders are on the rise. This has generated an enormous interest towards finding alternative approaches for management of UV-mediated damages. Chemoprevention via nontoxic agents, especially botanical antioxidants, is one such approach that is being considered as a plausible strategy for prevention of photodamages including photocarcinogenesis. In this review, we have discussed the photoprotective effects of resveratrol, an antioxidant found in grapes and red wine, against UVB exposure-mediated damages in vitro and in vivo. In addition, we have also discussed studies showing that resveratrol can act as a sensitizer to enhance the therapeutic effects of ionizing radiation against cancer cells. Based on available literature, we suggest that resveratrol may be useful for (1) prevention of UVB-mediated damages including skin cancer and (2) enhancing the response of radiation therapies against hyperproliferative, precancerous and neoplastic conditions. [source] Photosynthesis and Photoprotection in Overwintering PlantsPLANT BIOLOGY, Issue 5 2002W. W. Adams III Abstract: Seasonal differences in the capacity of photosynthetic electron transport, leaf pigment composition, xanthophyll cycle characteristics and chlorophyll fluorescence emission were investigated in two biennial mesophytes (Malva neglecta and Verbascum thapsus) that grow in full sunlight, and in leaves/needles of sun and shade populations of several broad-leafed evergreens and conifers (Vinca minor, Euonymus kiautschovicus, Mahonia repens, Pseudotsuga menziesii [Douglas fir], and Pinus ponderosa). Both mesophytic species maintained or upregulated photosynthetic capacity in the winter and exhibited no upregulation of photoprotection. In contrast, photosynthetic capacity was downregulated in sun leaves/needles of V. minor, Douglas fir, and Ponderosa pine, and even in shade needles of Douglas fir. Interestingly, photosynthetic capacity was upregulated during the winter in shade leaves/needles of V. minor, Ponderosa pine and Euonymus kiautschovicus. Nocturnal retention of zeaxanthin and antheraxanthin, and their sustained engagement in a state primed for energy dissipation, were observed largely in the leaves/needles of sun-exposed evergreen species during winter. Factors that may contribute to these differing responses to winter stress, including chloroplast redox state, the relative levels of source and sink activity at the whole plant level, and apoplastic versus symplastic phloem loading, are discussed. [source] Topical and systemic photoprotectionDERMATOLOGIC THERAPY, Issue 1 2003Cheryl F. Rosen ABSTRACT: Sunscreens are a valuable method of sun protection. Several new compounds are now available. It is important to remember, however, that photoprotection includes more than the use of sunscreens. There are a number of sun-protective behaviors that people can use to decrease their exposure to ultraviolet (UV) radiation. Dermatologists and other health professionals can work toward changing public policy, greatly increasing the ability of people to access shade. In addition, there is growing evidence about the effectiveness of other sun-protective agents. The only systemic medication for sun protection is ,-carotene, which is effective in erythropoietic protoporphyria (EPP). [source] Frontiers in sebaceous gland biology and pathologyEXPERIMENTAL DERMATOLOGY, Issue 6 2008Christos C. Zouboulis Abstract:, The development of experimental models for the in vitro study of human sebaceous gland turned down the theory of a phylogenetic relict and led to the identification of several, unknown or disregarded functions of this organ. Such functions are the production of foetal vernix caseosa, the influence of three-dimensional organization of the skin surface lipids and the integrity of skin barrier and the influence on follicular differentiation. In addition, the sebaceous gland contributes to the transport of fat-soluble antioxidants from and to the skin surface, the natural photoprotection, the pro- and antiinflammatory skin properties and to the innate antimicrobial activity of the skin. It is mainly responsible for skin's independent endocrine function, the hormonally induced skin ageing process, the steroidogenic function of the skin as well as its thermoregulatory and repelling properties and for selective control of the hormonal and xenobiotical actions of the skin. Interestingly, sebocytes, at least in vitro, preserve characteristics of stem-like cells despite their programming for terminal differentiation. This review reports on various sebaceous gland functions, which are currently under investigation, including its role on the hypothalamus,pituitary,adrenal-like axis of the skin, the impact of acetylcholine on sebocyte biology, the activity of ectopeptidases as new targets to regulate sebocyte function, the effects of vitamin D on human sebocytes, the expression of retinoid metabolizing cytochrome P450 enzymes and the possible role of sebum as vehicle of fragrances. These multiple homeostatic functions award the sebaceous gland the role ,brain of the skin' and the most important cutaneous endocrine gland. [source] New measures of photoprotectionEXPERIMENTAL DERMATOLOGY, Issue 2002Margaret Kripke No abstract is available for this article. [source] Molecular response to climate change: temperature dependence of UV-induced DNA damage and repair in the freshwater crustacean Daphnia pulicariaGLOBAL CHANGE BIOLOGY, Issue 4 2004Emily J. MacFadyen Abstract In temperate lakes, asynchronous cycles in surface water temperatures and incident ultraviolet (UV) radiation expose aquatic organisms to damaging UV radiation at different temperatures. The enzyme systems that repair UV-induced DNA damage are temperature dependent, and thus potentially less effective at repairing DNA damage at lower temperatures. This hypothesis was tested by examining the levels of UV-induced DNA damage in the freshwater crustacean Daphnia pulicaria in the presence and absence of longer-wavelength photoreactivating radiation (PRR) that induces photoenzymatic repair (PER) of DNA damage. By exposing both live and dead (freeze-killed) Daphnia as well as raw DNA to UV-B in the presence and absence of PRR, we were able to estimate the relative importance and temperature dependence of PER (light repair), nucleotide excision repair (NER, dark repair), and photoprotection (PP). Total DNA damage increased with increasing temperature. However, the even greater increase in DNA repair rates at higher temperatures led net DNA damage (total DNA damage minus repair) to be greater at lower temperatures. Photoprotection accounted for a much greater proportion of the reduction in DNA damage than did repair. Experiments that looked at survival rates following UV exposure demonstrated that PER increased survival rates. The important implication is that aquatic organisms that depend heavily on DNA repair processes may be less able to survive high UV exposure in low temperature environments. Photoprotection may be more effective under the low temperature, high UV conditions such as are found in early spring or at high elevations. [source] Fading of artificial hair colour and its prevention by photofiltersINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2006B. Locke Fading of artificial hair colour has been investigated by simulating actual usage conditions through exposure to artificial radiation in a weatherometer, with 0.35 mW (m2nm),1 at 340 nm, for 16,48 h, and by periodical washing. Hair colour was produced by using commercial two-part, permanent hair dyes with light auburn, medium auburn and dark auburn shades. Formulations based on red couplers, such as 4-amino-2-hydroxytoluene and 1-naphthol, as well as primary intermediates, such as 1-hydroxyethyl-4,5-diamino pyrazole sulphate, were employed. Results indicate that the extent of fading, as measured by the total colour change parameter, dE, is greatest for coloured hair subjected to both irradiation and shampooing, and significantly smaller for hair undergoing only irradiation or washing. Colour loss has been also found to be dependent upon the hair type employed, with coloured natural white and bleached hair undergoing much greater change than coloured brown hair. It has been also shown that hair colour based on pyrazole intermediates displayed the deepest fading as a result of shampooing (dE 4,6 after 10 shampooings) and irradiation per shampooing (dE 14,16 after 32 h of light exposure and four shampooings). The contribution of UV light (UVB + UVA) to the artificial hair-colour loss was found experimentally to be dependent upon the irradiation dose and varied from 63% at 16 h of irradiation time to 27% at 48 h of light exposure. The theoretical extent of photoprotection by a formulation was assessed by calculating the percentage of UV light it attenuates in the wavelength range from 290 to 400 nm. The results indicate that UVB photofilters, such as octyl methoxy cinnamate, absorb <25% of the total UV irradiation at concentrations as high as 30 mg (g hair),1. UVA absorbers were found to be more effective, with benzophenone-3 and benzophenone-4 absorbing about 40% of UV at the same concentration. Corresponding experimental data were in reasonable agreement with the theoretical predictions. The data are also presented for colour protection with treatments containing two photo-absorbers: benzophenone-3,ZnO; benzophenone-4,ZnO; octyl methoxy cinnamate,ZnO; and dimethylpabaimidopropyl laurdimonium tosylate-benzophenone-3. [source] Protective effects of a topical antioxidant mixture containing vitamin C, ferulic acid, and phloretin against ultraviolet-induced photodamage in human skinJOURNAL OF COSMETIC DERMATOLOGY, Issue 4 2008Christian Oresajo PhD Summary Background, Ultraviolet (UV) irradiation of the skin leads to acute inflammatory reactions, such as erythema, sunburn, and chronic reactions, including premature skin aging and skin cancer. Aim, In this study, the effects of a topical antioxidant mixture consisting of vitamin C, ferulic acid, and phloretin on attenuating the harmful effects of UV irradiation on normal healthy volunteers were studied using biomarkers of skin damage. Subjects/methods, Ten subjects (age, 18,60 years; Fitzpatrick skin types II and III) were randomized and treated with antioxidant product or vehicle control on the lower back for four consecutive days. On day 3, the minimal erythema dose (MED) was determined for each subject at a different site on the back. On day 4, the two test sites received solar-simulated UV irradiation 1,5× MED at 1× MED intervals. On day 5, digital images were taken, and 4-mm punch biopsies were collected from the two 5× MED test sites and a control site from each subject for morphology and immunohistochemical studies. Results, UV irradiation significantly increased the erythema of human skin in a linear manner from 1× to 5× MED. As early as 24 h after exposure to 5× MEDs of UV irradiation, there were significant increases in sunburn cell formation, thymine dimer formation, matrix metalloproteinase-9 expression, and p53 protein expression. All these changes were attenuated by the antioxidant composition. UV irradiation also suppressed the amount of CD1a-expressing Langerhans cells, indicating immunosuppressive effects of a single 5× MED dose of UV irradiation. Pretreatment of skin with the antioxidant composition blocked this effect. Conclusion, This study confirms the protective role of a unique mixture of antioxidants containing vitamin C, ferulic acid, and phloretin on human skin from the harmful effects of UV irradiation. Phloretin, in addition to being a potent antioxidant, may stabilize and increase the skin availability of topically applied vitamin C and ferulic acid. We propose that antioxidant mixture will complement and synergize with sunscreens in providing photoprotection for human skin. [source] Photoprotection: where do we stand?JOURNAL OF COSMETIC DERMATOLOGY, Issue 4 2006Electra Nicolaidou MD Summary Ultraviolet sun radiation can cause several deleterious effects on the skin, including photoaging and carcinogenesis. Physical protection and sunscreens are currently the two main types of photoprotection. Overall, people seem informed about the dangers of sun exposure, but sometimes they are not willing to implement the right sun-protection measures. Sunscreens are reported to be the most frequently used method worldwide, but they cannot substitute physical protection and a proportion of people do not apply them correctly. Public campaigns, together with fashion and the right role models, can still offer a lot in persuading people to change their habits towards a more sun-protected life. [source] PHOTOINHIBITION IN RED ALGAL SPECIES WITH DIFFERENT CAROTENOID PROFILES,JOURNAL OF PHYCOLOGY, Issue 6 2008Nadine Schubert Members of the Rhodophyta present different carotenoid profiles. In a majority of the species, lutein constitutes >50% of the total carotenoid content, while in other species, it is replaced by zeaxanthin or antheraxanthin. Given that carotenoids have specific roles in photoprotection, different carotenoid profiles of red algae species could be related to their capacity to cope with photoinhibitory stress. Therefore, in the present work, the sensitivity to light stress of red algal species with different carotenoid profiles was investigated. Photoinhibition of photosynthesis induced by high-light stress and the subsequent recovery in dim-light conditions was measured using maximal PSII quantum efficiency (Fv/Fm). The degree of decrease and recovery of Fv/Fm and their respective kinetics were related to the carotenoid profile of the species. Although no relationship between sensitivity to high-light stress and the carotenoid profile was observed, there were clear carotenoid profile-related differences in the decrease and recovery kinetics. In species with zeaxanthin or antheraxanthin as the major carotenoid, Fv/Fm reduction and recovery was principally associated with slowly activated and relaxed processes. In contrast, in species with lutein as the major carotenoid, rapidly activated processes appear to play a major role in the down-regulation of photosynthesis during light-stress conditions. In these species, the repair of D1 is also important during light-stress conditions. This finding could imply differential expression of mechanisms involved in photoprotection in red algae that seems to be related to the carotenoid profile of the species. [source] PHOTOSYNTHETIC PERFORMANCE, LIGHT ABSORPTION, AND PIGMENT COMPOSITION OF MACROCYSTIS PYRIFERA (LAMINARIALES, PHAEOPHYCEAE) BLADES FROM DIFFERENT DEPTHS,JOURNAL OF PHYCOLOGY, Issue 6 2006María Florencia Colombo-Pallotta Macrocystis pyrifera (L.) C. Agardh is a canopy-forming species that occupies the entire water column. The photosynthetic tissue of this alga is exposed to a broad range of environmental factors, particularly related to light quantity and quality. In the present work, photosynthetic performance, light absorption, pigment composition, and thermal dissipation were measured in blades collected from different depths to characterize the photoacclimation and photoprotection responses of M. pyrifera according to the position of its photosynthetic tissue in the water column. The most important response of M. pyrifera was the enhancement of photoprotection in surface and near-surface blades. The size of the xanthophyll cycle pigment pool (XC) was correlated to the nonphotochemical quenching (NPQ) of chl a fluorescence capacity of the blades. In surface blades, we detected the highest accumulation of UV-absorbing compounds, photoprotective carotenoids, ,XC, and NPQ. These characteristics were important responses that allowed surface blades to present the highest maximum photosynthetic rate and the highest PSII electron transport rate. Therefore, surface blades made the highest contribution to algae production. In contrast, basal blades presented the opposite trend. These blades do not to contribute significantly to photosynthetate production of the whole organism, but they might be important for other functions, like nutrient uptake. [source] Photoprotection of bacterial-derived melanin against ultraviolet A,induced cell death and its potential application as an active sunscreenJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 7 2008J Geng Abstract Background, The increase in the incidence of non-melanoma skin tumours, photoaging, and immunosuppression demand for more effective sunscreen on ultraviolet A (UVA) irradiation. Objectives, The aim of the study is to evaluate the photoprotective effects of a bacterial-derived melanin against UVA-induced damages in vitro and in vivo. Methods, Human fibroblasts were used to assess the role of the bacterial-derived melanin on cell viability against UVA. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and nuclear morphology were employed to evaluate the photoprotection at the cellular level. Fluorometric assays were performed to detect the formation of reactive oxygen species (ROS) in the cells. Evaluations of the bacterial-derived melanin as a sunscreen were measured by transmission test and persistent pigment darkening on human skin. Results, Bacterial-derived melanin efficiently scavenged ROS in the fibroblasts after UVA irradiation. The cell viability of xeroderma pigmentosum (XP) fibroblast treated with varied doses of melanin increased dramatically in comparison with untreated control and the treated XP fibroblasts became more resistant to UVA-induced apoptosis than normal fibroblasts. Although the relative transmission didn't change too much with different concentration of bacterial-derived melanin, this melanin could keep UVA-irradiated skin from pigment darkening and act as an active sunscreen on skin. Conclusions, The bacterial-derived melanin provided significant protection to fibroblast cell and human skin against the UVA radiation. It has the potential to be developed as an active sunscreen for the patients with photosensitivity skin to sun exposure. [source] Measurement of protection afforded by ultraviolet-absorbing window film using an in vitro model of photodamageLASERS IN SURGERY AND MEDICINE, Issue 4 2006Eric F. Bernstein MD Abstract Background and Objectives The effects of chronic sun damage including telangiectasias, solar lentigos, rhytides, enlarged pores, sagging skin, and pre-cancerous and cancerous growths are among the most common presenting complaints in a dermatologist's office. These changes are often worse on the driver's side of the face, emphasizing the role of UVA exposure received while driving in producing these changes. This study was undertaken to measure the ability of car window glass alone and in combination with ultraviolet (UV)-absorbing film to reduce UV-damage as measured using an established in vitro model of photoprotection. Study Design Materials and Methods Using the 3T3 neutral red uptake photoprotection assay with solar simulating radiation (SSR) administered by a xenon arc solar simulator, we measured the photoprotection ability of auto glass, window film that filters UV radiation, and the combination of window film and auto glass. Results As measured by the 3T3 neutral red uptake photoprotection assay, auto glass reduced cell death from SSR by 29%, while window film reduced it 90%, and the combination of auto glass and film reduced cell death by 93%, when compared to unfiltered SSR. Conclusions Window film that filters UV radiation results in dramatic reductions in cytotoxicity when measured by the neutral red uptake photoprotection assay. Widespread use of window film provides an ever-present barrier to ultraviolet A (UVA) exposure and could potentially reduce the detrimental effects of UVA, including photoaging, skin cancer, and ocular damage, such as cataracts. In addition, such film is essential for patients suffering from conditions sensitive to UV radiation, such as lupus erythematosis. Lasers Surg. Med. 38:337,342, 2006. © 2006 Wiley-Liss, Inc. [source] Multiple functional roles of flavonoids in photoprotectionNEW PHYTOLOGIST, Issue 4 2010Giovanni Agati First page of article [source] Winter down-regulation of intrinsic photosynthetic capacity coupled with up-regulation of Elip-like proteins and persistent energy dissipation in a subalpine forestNEW PHYTOLOGIST, Issue 2 2006C. Ryan Zarter Summary ,,Overwintering, sun-exposed and photosynthetically inactive evergreens require powerful photoprotection. The goal of this study was to seasonally characterize photosynthesis and key proteins/components involved in electron transport and photoprotection. ,,Maximal photosystem II (PSII) efficiency and photosynthetic capacity, amounts of zeaxanthin (Z), antheraxanthin (A), pheophytin and proteins (oxygen-evolving 33 kDa protein (OEC), PSII core protein D1 and subunit S (PsbS) protein, and members of the early light-inducible protein (Elip) family) were assessed in five conifer species at high altitude and in ponderosa pine (Pinus ponderosa) at moderate altitude during summer and winter. ,,Relative to summer, winter down-regulation of photosynthetic capacity and loss of PSII efficiency at the high-altitude sites were paralleled by decreases in OEC, D1, and pheophytin; massive nocturnal retention of (Z + A) and up-regulation of two to four proteins cross-reactive with anti-Elip antibodies; and no change in PsbS amount. By contrast, ponderosa pine at moderate altitude exhibited no down-regulation of photosynthetic capacity, smaller depressions in PSII efficiency, and less up-regulation of Elip family members. ,,These results support a function for members of the Elip family in the acclimation of sun-exposed needles that down-regulate photosynthesis during winter. A possible role in sustained photoprotection is considered. [source] In Vitro Antioxidant and In Vivo Photoprotective Effects of an Association of Bioflavonoids with Liposoluble VitaminsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2006Patrícia M. B. G. Maia Campos ABSTRACT A new tendency in cosmetic formulations is the association of botanical extracts and vitamins to improve skin conditions by synergic effects. The objective of this study was to determine the antioxidant activity of associated bioflavonoids, retinyl palmitate (RP), tocopheryl acetate (TA) and ascorbyl tetra-isopalmitate (ATIP), as well as their photoprotective effects in preventing increased erythema, transepidermal water loss (TEWL) and sunburn cell formation in hairless mouse skin. The antioxidant activity of solutions containing the association or each substance separately was evaluated in vitro by a chemiluminescence assay. The photoprotective effect was evaluated by means of in vivo tests. Dorsal skin of hairless mice was treated daily by topical applications for 5 days with formulations containing or not containing (vehicle) the flavonoid-vitamins association (5%). The skin was irradiated (UVA/B) 15 minutes after the last application. The results showed that bioflavonoids had in vitro antioxidant properties and also that when they were associated with vitamins their antioxidant activity was more pronounced. On the other hand, erythema and UV damage to the permeability barrier function (TEWL) was not significantly reduced by previous treatment with the flavonoid-vitamin-association formulations, when compared to the irradiated vehicle-treated area. However, the treatment protected the skin from UV damage because it reduced the number of sunburn cells, when compared to the vehicle-treated area. Finally, the association of vitamins and bioflavonoids added to a dermocosmetic formulation showed a relevant biological activity in terms of photoprotection, because the association of bioflavonoids and vitamins acted by different mechanisms, such as antioxidation and absorption of UV radiation, which suggests its use in antiaging and photoprotective products. [source] Radiation Sources Providing Increased UVNUVB Ratios Induce Photoprotection Dependent on the UVA Dose in Hairless MicePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2006Vivienne E. Reeve ABSTRACT In studies involving mice in which doses of UVA (320,400 nm) and UVB (290,320 nm) radiation were administered alone or combined sequentially, we observed a protective effect of UVA against UVB-induced erythemdedema and systemic suppression of contact hypersensitivity. The UVA immunoprotection was mediated by the induction of the stress enzyme heme oxygenase-1 (HO-1) in the skin, protection of the cutaneous Th1 cytokines interferon-gM (IFN-,) and IL-12 and inhibition of the UVB-induced expression of the Th2 cytokine IL-10. In this study, we seek evidence for an immunological waveband interaction when UVA and UVB are administered concurrently to hairless mice as occurs during sunlight exposure in humans. A series of spectra providing varying ratios of UVA/UVB were developed, with the UVA ratio increased to approximately 3.5 times the UVA component in solar simulated UV (SSUV). We report that progressively increasing the UVA component of the radiation while maintaining a constant UVB dose resulted in a reduction of both the erythemdedema reaction and the degree of systemic immunosuppression, as measured as contact hypersensitivity. The UVA-enhanced immunoprotection was abrogated in mice treated with a specific HO enzyme inhibitor. UVA-enhanced radiation also upregulated the expression of cutaneous IFN-, and IL-12 and inhibited expression of both IL-6 and IL-10, compared with the activity of SSUV. The results were consistent with the previously characterized mechanisms of photoprotection by the UVA waveband alone and suggest that the UVA component of solar UV may have beneficial properties for humans. [source] Zeolite Encapsulation Decreases TiO2 -photosensitized ROS Generation in Cultured Human Skin Fibroblasts,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2006Biao Shen ABSTRACT Sunscreens protect skin against sunburn. However, studies have demonstrated that UV-irradiated sunscreen components such as titanium dioxide (TiO2) promote the photogeneration of reactive oxygen species (ROS). Because encapsulation of TiO2 within zeolites alters its photocatalytic activity, supra-molecular composites based on NaY zeolite hosts containing TiO2 guests were prepared, and the effects on ROS formation in cells under UVA-irradiation evaluated. DCFH-DA (2,,7,-dichlorofluorescein diacetate) was used as a profluorescent probe to monitor intracellular ROS. The detection of in-tracellular 2,,7,-dichlorofluorescein (DCF) fluorescence by confocal microscopy revealed that DCFH-DA was taken up, hydrolyzed and oxidized by yeast cells and cultured human skin fibroblasts within 20 and 6 min, respectively. Higher DCF fluorescence was observed in fibroblasts following UVA irra-diation in the absence but not in the presence of the radical nitroxide, TEMPOL (4-hydroxy-2,2,6,6-tetramethylpipery-dine-1-oxyl), which exhibits superoxide dismutase-mimetic and catalase-mimetic activity. UVA-induced fluorescence increased by -50% in the presence of 32-nm anatase TiO2 particles and decreased by essentially an equal amount in the presence of TiO2 encapsulated within NaY zeolites (TiO2@NaY). Addition of the uncomplexed NaY host also decreased (by ,30%) the amount of UVA-induced fluorescence but, un-expectedly, the combination of the free guest and host (TiO2@NaY) caused a doubling of the fluorescence. Protection of cells against TiO2 -induced intracellular ROS by encapsulation suggests that supramolecular species may be beneficial in photoprotection of the skin. In contrast, the potentiation of TiO2 -induced ROS by uncomplexed NaY points to a critical role for formulation when free TiO2 is used as a sun screen ingredient. [source] Photostabilization of an Entomopathogenic Fungus Using Composite Clay Matrices,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2003Ephraim Cohen ABSTRACT To provide photostabilization for entomopathogenic fungi by anionic dyes, composite matrices based on clay,biopolymer combinations were prepared. In the first step, the negative surface charge of various clays (montmorillonite, attapulgite, bentonite and kaolinite) was reversed to positive by adsorption to the polycationic biopolymer chitosan. The second step involved adsorption of the toxicologically safe anionic dyes fast green (FG) and naphthol yellow S (NYS) to the clay complexes. Compared with cytotoxic photoprotectants like berberine, palmatine and acriflavine, the anionic dyes have no adverse effects up to a concentration of 1 M. In assays using various clay,chitosan,dye matrices and UV irradiation from a lamp source, it was evident that both FG and NYS provided considerable photostabilization for conidia of the entomopathogenic fungus Aschersonia spp. that served as a model biocontrol agent. Apparently, because of the light-dispersing property, bentonite and attapulgite per se provided significant photoprotection. All clay matrices containing FG provided a substantial photostabilization effect. [source] A New Model Using Liposomes That Allow to Distinguish Between Absorption and Oxidative Properties of Sunscreens,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2002Christian Tran ABSTRACT We have developed a new model using liposome-encapsulated fluorescent probes, aiming at assessing both the physical and the biological protection provided by filter molecules such as those incorporated in sunscreens. The fluorescent indicator Indo-1 or 2,,7,-dichlorofluorescin (DCFH) was inside the liposomes, in the aqueous inner compartment, whereas the filter molecules octyl methoxycinnamate (OMC), benzophenone-3 (BP3) or avobenzone, widely used in sunscreens, were incorporated into liposome membranes. When liposome suspensions were placed in a fluorometer cuvette exposed to an incident UV beam, the decrease of Indo-1 fluorescence as a function of filter concentration was related to the extinction coefficient of the filters. On the other hand, when liposome suspensions were exposed to moderate UVB doses allowing Indo-1 photobleaching, the remaining intact Indo-1 was linked to the protection provided by filter-containing liposome membranes. Finally, when liposome-encapsulated DCFH was exposed to UVB, the degree of photo-oxidation of the fluorescent probe into 2,,7,-dichlorofluorescein accounted for the photoprotection provided by the filter contained in liposome membranes. BP3 was more potent and slightly less efficient than the other two filters in preventing Indo-1 fluorescence; all three filters provided a similar concentration-dependent protection of Indo-1 photobleaching, whereas only OMC was able to prevent the photooxidation of DCFH. The liposome model presented here has the advantage of combining both physical and biological parameters to assess the photoprotection provided by filter molecules, and the lack of photoprotection by two sunscreen molecules having a good filter capacity highlights the need for such a biological parameter when talking about the safety of sunscreens. [source] Vitamin D in health and diseasePHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2010Matteo C. LoPiccolo Background/purpose: Investigations have revealed that vitamin D plays an important role in many areas of health and disease. Questions over whether sun avoidance and sunscreen use will decrease vitamin D levels may concern clinicians when counseling patients at risk for vitamin D insufficiency. A review of the role of vitamin D in health and disease, the impact of photoprotection and skin type on vitamin D levels, and recommendations for adequate vitamin D intake is provided to aid clinicians in counseling patients regarding these issues. Results: Review of the literature indicates that adequate vitamin D intake is associated with decreased risk of falls and bone fractures in the elderly, breast and gastrointestinal cancer risk, cardiovascular disease, and possibly all cause mortality, diabetes, and multiple sclerosis. While skin type does affect vitamin D levels, regular use of sunscreen is not associated with vitamin D insufficiency. Conclusions: Adequate intake of vitamin D is important for maintenance of good health, and may be achieved through diet and oral supplementation. Intentional or prolonged exposure to ultraviolet light should not be used as a means of obtaining vitamin D. [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] Anti-wrinkling effects of the mixture of vitamin C, vitamin E, pycnogenol and evening primrose oil, and molecular mechanisms on hairless mouse skin caused by chronic ultraviolet B irradiationPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2007Ho-Song Cho Background: Naturally occurring antioxidants were used to regulate the skin damage caused by ultraviolet (UV) radiation because several antioxidants have demonstrated that they can inhibit wrinkle formation through prevention of matrix metalloproteinases (MMPs) and/or increase of collagen synthesis. Objective: We examined the effect of oral administration of the antioxidant mixture of vitamin C, vitamin E, pycnogenol, and evening primrose oil on UVB-induced wrinkle formation. In addition, we investigated the possible molecular mechanism of photoprotection against UVB through inhibition of collagen-degrading MMP activity or through enhancement of procollagen synthesis in mouse dorsal skin. Methods: Female SKH-1 hairless mice were orally administrated the antioxidant mixture (test group) or vehicle (control group) for 10 weeks with UVB irradiation three times a week. The intensity of irradiation was gradually increased from 30 to 180 mJ/cm2. Microtopographic and histological assessment of the dorsal skins was carried out at the end of 10 weeks to evaluate wrinkle formation. Western blot analysis and EMSA were also carried out to investigate the changes in the balance of collagen synthesis and collagen degradation. Results: Our antioxidant mixture significantly reduced UVB-induced wrinkle formation, accompanied by significant reduction of epidermal thickness, and UVB-induced hyperplasia, acanthosis, and hyperkeratosis. This antioxidant mixture significantly prevented the UVB-induced expressions of MMPs, mitogen-activated protein (MAP) kinase, and activation of activator protein (AP)-1 transcriptional factor in addition to enhanced type I procollagen and transforming growth factor-,2 (TGF-,2) expression. Conclusion: Oral administration of the antioxidant mixture significantly inhibited wrinkle formation caused by chronic UVB irradiation through significant inhibition of UVB-induced MMP activity accompanied by enhancement of collagen synthesis. [source] An update on photoprotectionPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 1 2002Gillian M. Murphy First page of article [source] | |||||||||||||||||||||||||