An Experimental Model Design for Photoaging.

UNLABELLED: Autologous adipose-derived stem cells have shown great promise in applications that treat photodamaged skin. Adipose-derived stem cells also have an antiwrinkle effect; consequently, they have become a topic of primary interest. Nude mice have been used extensively in studies of adipose-derived stem cells, human dermal fibroblasts, and other filler injections. However, a nude mouse model of photoaging has not yet been developed. Thus, we attempted to develop a nude mouse model of photoaging in this study. MATERIALS AND METHODS: Fourteen, 5-week-old female BALB/c nude mice were irradiated with ultraviolet-B rays, 6 times a week for 6 weeks. The minimum erythema dose was established before the mice underwent ultraviolet irradiation to minimize the inflammation of the irradiated skin and to determine the initial irradiation dosage. The mean sizes of the wrinkled areas of skin and the mean depths of the wrinkles were compared between the study groups using replica analysis. Skin biopsies were performed on the 6th and 10th weeks of the study. RESULTS: The mean sizes of the wrinkled areas of skin and the mean depths of the wrinkles increased significantly in the ultraviolet-B-irradiated nude mice compared with the nonirradiated mice, and the thicknesses of the epidermis and dermis of the skin from the upper and lower back were significantly greater after ultraviolet-B irradiation up to the 6th week of treatment (P < 0.05). Furthermore, the ultraviolet-B-irradiated group demonstrated reduced collagen fiber levels. CONCLUSIONS: We have successfully developed a nude mouse model for research into photoaging, and these results indicate that the nude mouse is a suitable model for investigating the development of photoaging.

Ultraviolet-C irradiation to titanium implants increases peri-implant bone formation without impeding mineralization in a rabbit femur model.

OBJECTIVES: Volume and bone quality of peri-implant supporting bone, in particular, at implant neck region, as well as bone-implant contact ratio, is important for long-term stability of implants. Ultraviolet-C (UVC) irradiation is known to enhance the osseointegration capability of titanium implants. However, the histological determination was performed only on a rat model, but not pre-clinical animal model such as a rabbit model. The purpose of this study was to determine the effects of UVC irradiation on titanium implants on the volume and mineral density of peri-implant supporting bone formation in a rabbit femur model. MATERIALS AND METHODS: Acid-etched pure titanium screw implants with or without 3 mW/cm2 UVC irradiation for 48 h were placed in rabbit femur diaphyses. Peri-implant bone tissue formation was analyzed at 3 and 8 weeks post-operatively by histology and micro-CT-based bone morphometry after calibration with hydroxyl apatite phantoms. RESULTS: UVC pre-irradiated implants accumulated a higher density of cells and thicker and longer bone tissue attachments that continued into the inner basic lamellae of the surface of existing cortical bone at 3 and 8 weeks than the implants without irradiation. Although the bone mineral density around both implants was equivalent to that of the existing cortical bone, bone volume was greater with UVC pre-irradiation in two-thirds or more of the apical region throughout the observation period. CONCLUSIONS: These results indicate that UVC treatment increased the volume of cortical-like bone tissue in the coronal region of titanium implants without deterioration of bone mineral density.

Ultraviolet radiation and cutaneous malignant melanoma.

Essential features of the epidemiology and photobiology of cutaneous malignant melanoma (CMM) in Norway were studied in comparison with data from countries at lower latitudes. Arguments for and against a relationship between ultraviolet radiation (UV) from sun and artificial light and CMM are discussed. Our data indicate that UV is a carcinogen for CMM and that intermittent exposures are notably melanomagenic. This hypothesis was supported both by latitude gradients, by time trends and by changing patterns of tumor density on different body localizations. However, even though UV radiation generates CMM, it may also have a protective action and/or an action that improves prognosis. There appears to be no, or even an inverse latitude gradient for CMM arising on non-UV exposed body localizations (uveal melanoma, CMMs arising in the vulva, perianal/anorectal regions, etc.). Furthermore, CMM prognosis was gradually improved over all years of increasing incidence (up to 1990), but during the past 20 years, incidence rates stabilized and prognosis was not improved significantly. Comparisons of skin cancer data from Norway, Australia and New Zealand indicate that squamous cell carcinoma and basal cell carcinoma are mainly related to annual solar UVB fluences, while UVA fluences play a larger role of CMM.

Evaluation of varying concentrations of nano-oxides as ultraviolet protective agents when incorporated in maxillofacial silicones: an in vitro study.

STATEMENT OF PROBLEM: A silicone prosthesis used to rehabilitate defects caused by cancer does not usually protect the underlying skin from ultraviolet light. Additives to the maxillofacial material may add ultraviolet protection. PURPOSE: The purpose of this study was to evaluate the degree of ultraviolet protection after incorporating varying concentrations of nano-oxides in Cosmesil M511 medical grade silicone elastomer. MATERIAL AND METHODS: Nanosized oxides of Zn and Ti were added in various concentrations (0.5%, 1.0%, 1.5%, 2.0%, and 2.5% by weight) to a silicone elastomer. Cosmesil M511 silicone without nano-oxides served as the control group for 11 experimental groups. All specimens were subjected to ultraviolet radiation with ultraviolet A (>315-400 nm) and ultraviolet B (>280-315 nm), and the percentage transmission was measured with an ultraviolet spectrophotometer. The ultraviolet protection factor was calculated. The Mann-Whitney U test was used to evaluate which of the groups differed significantly (α=.05). The Wilcoxon signed rank test was used to test the difference in values obtained for both ultraviolet ranges. RESULTS: Spectrophotometric analysis indicated that the percentage-of-transmission values decreased for both the nano-oxide groups for the ultraviolet A and B ranges (P<.05) compared with the control group. The ultraviolet protection factor values increased considerably as the percentage concentration of nano-oxides was increased for both ultraviolet ranges (P<.05). CONCLUSIONS: Compared with Ti nano-oxides (2% to 2.5%), Zn nano-oxides in lesser concentrations provided more significant and consistent ultraviolet protection in Cosmesil M511 elastomer.

[Comparison of ultraviolet A and ultraviolet B on 1,25-dihydroxy-vitamin D3 and bone metabolism in ovariectomized rats].

OBJECTIVE: To investigate the effects of ultraviolet A (UVA) and ultraviolet B (UVB) on serum 1,25-dihydroxy-vitamin D3 and bone metabolism of ovariectomized rats and to compare them on bone metabolism. METHODS: In the study, 40 six-month female Sprague-Dawley rats were randomly divided into sham-operated control group (sham), osteoporosis model group (OVX), UVA irradiation group (OVX+UVA) and UVB irradiation group (OVX+UVB). Except the sham-operated control group, the remaining rats were ovariectomized to establish the osteoporosis models. After the model establishment, the UVA and UVB groups were exposed to UV irradiation with wavelengths of 340 nm and 313 nm, respectively. After the 15-week UV irradiation treatment, bone material density and serum 1,25(OH)2D3, osteocalcin (bone gamma-carboxyglutamic acid protein, BGP), calcium (Ca) and phosphorus (P) contents were measured. RESULTS: Compared with the sham group, the body weights [(486.5±55.7) g, (488.3±32.1) g, (494.1±49.8) g, vs. (408.6±36.1) g, P<0.01] were significantly higher in the model group, UVA group and UVB group; proximal femur BMD [(0.318±0.025) g/cm(2), (0.316±0.031) g/cm(2), (0.322±0.036) g/cm(2), vs.(0.386±0.027) g/cm(2), P<0.01], central BMD [(0.321±0.038) g/cm(2), (0.319±0.051) g/cm(2), (0.320±0.053) g/cm(2), vs.(0.347±0.044) g/cm(2), P<0.05], distal femur BMD [(0.320±0.028) g/cm(2), (0.318±0.030) g/cm(2), (0.322±0.036) g/cm(2), vs.(0.361±0.046) g/cm(2), P<0.01] were significantly lower in the model group, UVA group and UVB group. After the 15-week treatment of UV radiation, compared with the sham group, proximal femur BMD [(0.162±0.125) g/cm(2) vs.(0.293±0.076) g/cm(2), P<0.01], central BMD [(0.205±0.102) g/cm(2) vs.(0.306±0.031) g/cm(2), P<0.01] , distal femur BMD [(0.153±0.119) g/cm(2) vs.(0.274±0.017) g/cm(2), P<0.01] were significantly decreased in the model group; serum 1,25(OH)2D3 [(19.80±1.67) ng/L vs. (28.35±4.32) ng/L, P<0.01], BGP [(11.00±0.01) ng/L vs.(16.64±0.01) ng/L,P<0.01] and Ca [(2.14±0.10) mmol/L vs.(2.68±0.16) mmol/L,P<0.01] were significantly lower in the model group. Compared with the model group, proximal femur BMD [(0.248±0.092) g/cm(2), (0.218±0.123) g/cm(2), vs.(0.162±0.125) g/cm(2), P<0.01], central BMD [(0.272±0.010) g/cm(2), (0.275±0.036) g/cm(2), vs.(0.205±0.102) g/cm(2), P<0.01] and distal femur BMD [(0.251±0.009) g/cm(2), (0.242±0.063) g/cm(2), vs.(0.153±0.119) g/cm(2), P<0.01] were significantly increased in the UVA group and UVB group; serum 1,25(OH)2D3 [(29.47±4.54) ng/L, (27.56±6.33) ng/L, vs.(19.80±1.67) ng/L, P<0.01], BGP[(15.70±0.01)ng/L, (15.62±0.02) ng/L, vs.(11.00±0.01) ng/L, P<0.01] and Ca [(2.48±0.22) mmol/L, (2.58±0.13) mmol/L, vs.( 2.14±0.10) mmol/L, P<0.01] were significantly higher in the UVA group and UVB group. There were no statistical differences among the UVA group, UVB group and sham group. CONCLUSION: Both UVA and UVB may improve serum 1,25(OH)2D3 content of ovariectomized rats, promote bone formation, increase bone material density, and relieve bone loss due to osteoporosis.

Is the Global Solar UV Index an effective instrument for promoting sun protection? A systematic review.

Exposure to ultraviolet radiation is an important risk factor for skin cancer. The Global Solar Ultraviolet Index (UVI) was developed as a tool to visualize the amount of harmful radiation and to encourage people to use sun protection. We conducted a systematic review of the effectiveness of the UVI. We employed a comprehensive search strategy to explore the impact of the UVI on five outcome categories. Twenty-seven of a total of 260 studies met our inclusion criteria; data extraction and quality appraisal were undertaken for 25 studies, comprising 3 randomized controlled trials, 2 non-randomized intervention studies and 20 cross-sectional studies. Nearly half of these studies were from Australia and New Zealand. We found low to intermediate levels of UVI awareness and low levels of UVI understanding. Studies rated moderate or strong suggest that the UVI does not influence knowledge, attitudes, sun protection behavior or sun exposure. Overall, the findings imply that the UVI, as currently implemented, has not been successful at improving sun protection practices and reducing sun exposure among the population at large. Drawing on experience with theory-based sun protection programs, we advocate for more realistic expectations of what the UVI can and cannot achieve.

Photo/photochemical oxidation of cyanide and metal-cyanide complexes: ultraviolet A versus ultraviolet C.

Degradation of free cyanide (CN(-)), weak-acid dissociable (WAD) (Zn(CN)4(2-), Cu(CN)3(2-)) and strong-acid dissociable (SAD) (Fe(CN)6(4-) cyanide complexes by photo and photochemical oxidation with ultraviolet (UV) light and H2O2 was investigated. The experiments were performed in batch reactors under ultraviolet A (UVA; 395 nm) and ultraviolet C (UVC; 254 nm) light; the degradation efficiency was followed in terms of free cyanide, complex and metal concentrations. UVC and UVA photo-oxidations were found to be equally effective in CN(-) and WAD degradation, while the degradation of the SAD complex was more difficult for both UV wavelengths, and UVC was more effective. The initial pH of the solution has influenced the degradation of all cyanide species and the optimum initial pH was evaluated as 10.5 for CN(-) and Cu(CN)3(2-); 12.0 for Zn(CN)4(2-) and 9.0 for Fe(CN)6(4-) degradation. Photochemical oxidation using H202 provided higher degradation at shorter durations with both UVA and UVC. Time-dependent variations in free cyanide and metal concentrations have indicated that metal-cyanide complexes are firstly degraded into metal and CN(-) ions, followed by oxidation of CN(-) ions, while metals in the system were partially removed as hydroxide precipitates. Therefore, depending upon the effluent requirements, the studied UV photo/photochemical oxidations were offered as either a pre-treatment method for the separation of metal and the cyanide, or as an oxidation technology to degrade especially WAD complexes and CN(-). Estimated operational cost of photo-oxidation by UVC was 1.6-2.5-fold higher than UVA degradation, although degradation times were close. In the photochemical oxidation with H2O2, the operational costs of UVC and UVA degradation were closer, owing to peroxide costs, but UVC was still more expensive.

Shining light on multi-drug resistant Candida auris: Ultraviolet-C disinfection, wavelength sensitivity, and prevention of biofilm formation of an emerging yeast pathogen.

Candida auris is an emerging fungal superbug of worldwide interest. It is associated with high mortality rates and exhibits increased resistance to antifungals. Ultraviolet subtype C (UVC) light can be used to disinfect surfaces to mitigate its spread. The objectives of this study were (1) To investigate UVC disinfection performances and wavelength sensitivity of C. auris. (2) To evaluate the UVC dose required for the prevention of biofilm formation on stainless-steel, plastic (polystyrene), and poly-cotton fabric surfaces. C. auris was grown following standard procedures. The study utilized six different UVC LED arrays with wavelengths between 252 and 280 nm. Arrays were set at similar intensities, to obtain doses of 5-40 mJ cm-2 and similar irradiation time. Disinfection performance for each array was determined using log reduction value (LRV) and percentage reduction by comparing the controls against the irradiated treatments. Evaluation of the ability of 267 nm UVC LEDs to prevent C. auris biofilm formation was investigated using stainless-steel, plastic coupons, and poly-cotton fabric. Peak sensitivity to UVC disinfection was between 267 and 270 nm. With 20 mJ cm-2 , the study obtained ≥LRV3. On stainless-steel coupons, 30 mJ cm-2 was sufficient to prevent biofilm formation, while on plastic, this required 10 mJ cm-2 . A dose of 60 mJ cm-2 reduced biofilms on poly-cotton fabric significantly (R2 = 0.9750, p = 0.0002). The study may allow for the design and implementation of disinfection systems.

[Comprehensive hygienic assessment of solaria].

The paper gives data on the positive and negative effects of human exposure to ultraviolet radiation (UVR). It provides the hygienic characteristics of solaria used to produce an artificial tan. This device has been found to present a high health risk to its users. There are considerable problems in the hygienic assessment of this type of exposure. The ways of solving the arising problems in developing the metrological monitoring of UVR and compiling a document regulating the sanitary-and-epidemiological surveillance of solaria are defined.

Differences in the Effects of Broad-Band UVA and Narrow-Band UVB on Epidermal Keratinocytes.

BACKGROUND: The sun is a natural source of UV radiation. It can be divided into three bands, UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm), where the radiation up to 290 nm is very effectively eliminated by the stratospheric ozone. Although UV radiation can have a beneficial effect on our organism and can be used in the treatment of several skin diseases, it must primarily be considered harmful. METHODS: In the presented work, we focused on the study of the longer-wavelength UV components (UVA and UVB) on the human epidermal keratinocyte line HaCaT. As UVA and UVB radiation sources, we used commercially available UVA and UVB tubes from Philips (Philips, Amsterdam, The Netherlands), which are commonly employed in photochemotherapy. We compared their effects on cell viability and proliferation, changes in ROS production, mitochondrial function and the degree of DNA damage. RESULTS: Our results revealed that UVB irradiation, even with significantly lower irradiance, caused greater ROS production, depolarization of mitochondrial membrane potential and greater DNA fragmentation, along with significantly lowering cell viability and proliferative capacity. CONCLUSIONS: These results confirm that UV radiation causes severe damages in skin cells, and they need to be protected from it, or it needs to be applied more cautiously, especially if the component used is UVB.

Printable UV-Light Sensor for Human Eye Protection.

Light-emitting diode based electronic screens emit near-ultraviolet radiation, which causes harm to the human eye after prolonged exposure. Thus, it is of paramount importance to prepare a sensitive and adjustable visible near-ultraviolet sensor for retinal warning. Herein, a series of bipyridine derivatives were synthesized to investigate effects of substituent groups and anions on photochromic properties via both experimental and theoretical studies. The introduction of dual hydrogen bonding urea onto substituted groups significantly accelerated the photochromic rate due to strong intermolecular interactions, which reduces molecular spacing and promotes the electron-transfer effect. Moreover, the photochromic rate was tuned by changing the size of the anion. Larger anions widen the molecular spacing and weaken the electron transfer and eventually lead to a decrease in the photochromic rate. Finally, bipyridine derivatives were printed on a polyethylene terephthalate film or paper as a sensitive, adjustable, and visible sensor to monitor near-ultraviolet radiation emitted by an light-emitting diode screen.

The Associations Between Light Exposure During Pumping and Holder Pasteurization and the Macronutrient and Vitamin Concentrations in Human Milk.

BACKGROUND: During pumping, storage, and pasteurization human milk is exposed to light, which could affect the concentrations of light-sensitive vitamins. Currently, milk banks do not regulate light exposure. RESEARCH AIM: The aim of this paper was to determine the influence of light exposure during pumping, storage, and pasteurization on (1) macronutrients, (2) select water-soluble vitamins, and (3) select fat-soluble vitamins. METHODS: All 13 participants donated 4 milk samples each. Each sample underwent 1 of 4 treatments: raw and light protected, raw and light exposed, pasteurized and light protected, and pasteurized and light exposed. Samples were analyzed for macronutrients and Vitamins B1, B2, retinol, γ-tocopherol, α-tocopherol, and ß-carotene. RESULTS: ß-carotene concentrations were not influenced by light exposure. Vitamin B1 was significantly (p < 0.05) affected by light-exposure (M = 0.23, SD = 0.01mg/L) compared to light-protected (M = 0.27, SD = 0.01mg/L) samples. Vitamin B2 concentrations were reduced (p < 0.05) by light-exposure in raw (M = 62.1, SD = 0.61µg/L) and pasteurized (M = 73.7, SD = 0.72µg/L) samples compared to light-protected raw samples (M = 99.7, SD = 0.66µg/L). No other tested nutrients were affected by light exposure. CONCLUSIONS: If milk is exposed to excessive amounts of light, Vitamins B1 and B2 concentrations may degrade below the current Adequate Intake recommendations for infants 0-6 months of age, increasing the risk of insufficient vitamin supply to the exclusively human milk-fed infant. Thus, pumped or processed human milk should be protected from light to preserve milk vitamin concentrations.

Photocatalytic antibacterial effect of TiO(2) film of TiAg on Streptococcus mutans.

OBJECTIVE: To test through various oxidation procedures the differences in antibacterial activities against Streptococcus mutans (S mutans) of Titanium (Ti) and Titanium silver (TiAg) metals coated with TiO(2). MATERIALS AND METHODS: This study examined the photocatalytic antibacterial effects on S mutans of Ti and TiAg ubstrates coated with two crystalline forms of TiO(2) by thermal and anodic oxidation. A bacterial suspension of S mutans was pipetted onto TiO(2)-coated metal specimens and uncoated specimens with ultraviolet A (UVA) illumination for 20 to 100 minutes. The same specimen without UVA was used as the control. The level of colony-forming units of S mutans after UVA illumination was compared with that of the control. RESULTS: The level of colony-forming units of S mutans was significantly lower on TiO(2)-coated Ti and TiAg metal specimens after UVA illumination than on uncoated Ti and TiAg specimens. The level of colony-forming units of S mutans was significantly lower on the metals coated by anodic oxidation than on those coated by thermal oxidation. The TiO(2) coating on TiAg had a significantly higher and more rapid antibacterial effect than did the TiO(2) coating on Ti. CONCLUSIONS: The antibacterial effect of a TiO(2) film formed by anodic oxidation was superior to that formed by thermal oxidation. The addition of Ag to the Ti specimen indicated a synergistic effect on the photocatalytic antibacterial property against S mutans.

Is Vitamin D Level at Melanoma Diagnosis Associated With Stage Of Tumor? An Observational Study of Melanoma Patients Living in a High Ultraviolet Radiation Environment.

OBJECTIVES: This study will assess the relationship between vitamin D concentration at melanoma diagnosis and melanoma tumor characteristics, in individuals in a high ultraviolet radiation (UVR) environment. METHODS: We aim to recruit 600 recently diagnosed melanoma patients from Queensland, Australia, a high UVR location with one of the world's highest melanoma incidence rates. Patients are recruited through general practitioner, skin cancer specialist, dermatological and hospital-based practices. As close as possible to diagnosis, participants provide a blood sample for vitamin D analysis and have their sun exposure/sun protection behavior, melanoma risk factors and dietary vitamin D intake assessed by questionnaire and phone interview. Details of tumor pathology, including tumor level, thickness, and ulceration, are abstracted from cancer registry records. Here, we describe the study methods and present preliminary findings from early participants. RESULTS: As of December 2017, we have recruited 128 participants (48% male, mean age 60.2 years, mean Breslow thickness 0.63 mm). CONCLUSIONS: When complete, this study will give insights into the association between vitamin D at diagnosis and melanoma tumor characteristics whilst adjusting for recent sun exposure and sun protection use. This study may impact military sun exposure and nutrition policies as vitamin D may play a role in melanomagenesis.

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation.

Airborne bacteria-containing bioaerosols have attracted increased research attention on account of their adverse effects on human health. Ultraviolet germicidal irradiation (UVGI) is an effective method to inactivate airborne microorganisms. The present study models and compares the inactivation performance of three UV sources in the UVGI for aerosolized Escherichia coli. Inactivation efficiency of 0.5, 2.2 and 3.1 logarithmic order was obtained at an exposure UV dose of 370 J/m3 under UVA (365 nm), UVC (254 nm) and UVD (185 nm) sources, respectively. A Beer-Lambert law-based model was developed and validated to compare the inactivation performances of the UV sources, and modeling enabled prediction of inactivation efficiency and analysis of the sensitivity of several parameters. Low influent E. coli concentrations and high UV doses resulted in high energy consumption (EC). The change in airborne endotoxin concentration during UV inactivation was analyzed, and UVC and UVA irradiation showed no marked effect on endotoxin degradation. By contrast, both free and bound endotoxins could be removed by UVD treatment, which is attributed to the ozone generated by the UVD source. The results of this study can provide a better understanding of the air disinfection and airborne endotoxin removal processes.

Commentary on 'UVB-SPF': the SPF labels of sunscreen products convey more than just UVB protection.

The FDA recently published a proposed amendment of the Final Monograph for OTC Sunscreen Products. Among the proposals, FDA revised solar simulator performance specifications and additional labeling for sunscreen products. The maximum allowable labeled sun protection factor (SPF) was increased to SPF 50 while simultaneously requiring it to be called 'UVB-SPF'. UVB accounts for 80-91% of the erythemic effectiveness of the UV solar simulator specified in the amendment. Analysis of the specified solar simulator spectrum used to determine SPF indicates that if 100% of the UVB is blocked, it is mathematically impossible to achieve an SPF in excess of approximately 11 without also blocking at least some UVA. Consequently significant UVA protection must be provided for sunscreen products to achieve SPFs of 15 and higher. At the maximum allowed SPF 50, where only 2% or less of the effective UV risk remains, the minimum reduction of UVA erythemal effectiveness must by definition be 78-90%. While mandating UVA protection criteria is doubtless important, especially as it relates to sunscreen photostability, there is no utility in, or basis for, the proposed 'UVB-SPF' descriptor as existing high SPF labeling indicates both UVB and UVA protection.

Sunscreens containing the broad-spectrum UVA absorber, Mexoryl SX, prevent the cutaneous detrimental effects of UV exposure: a review of clinical study results.

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 Mexoryls 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: Mexoryls 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 Mexoryls 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, Mexoryls SX formulations always showed a higher protective potency than sunscreen without it even when the protection against erythema was similar (products with same SPF). Mexoryls 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: Mexoryls 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.

Sun Exposure Public Health Directives.

There have been many public health recommendations for avoiding UV radiation exposures. This is primarily due to concerns about skin cancer and especially melanoma, the most serious type of skin cancer. However, UV radiation is also known as the primary source of vitamin D and other compounds needed for good health. This brief commentary lists several of the many important recent studies of adverse health effects associated with low sun exposure, including some specific cancers, multiple sclerosis, diabetes, cardiovascular disease, autism, Alzheimer's disease, and age-related macular degeneration. Our conclusion is that non-burning UV exposure is a health benefit and-in moderation-should be recommended as such.

The interaction of UVA and UVB wavebands with particular emphasis on signalling.

The molecular response mechanisms and signalling pathways activated upon exposure to ultraviolet (UV) radiation have been extensively studied within the last two decades. Although many signalling pathways can be activated by both UVA as well as UVB, there are several distinctions indicating wavelength-specific response patterns accommodated by the terms UVA response and UVB response. Given that human skin is primarily exposed to UV light from solar radiation consisting of both UVA and UVB, we sought to explore a potential interaction between the distinct UVA and UVB responses at the level of MAPK. Our results indicate that the two distinct stress responses elicited by UVA or UVB interact with each other, producing a "third" response that is different from either alone and cannot be explained by a simple addition of effects.