Doses Of Ultraviolet Radiation Research Articles

Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+ ,Dy3+ co-doped Ba2 MgSi2 O7 phosphors.

In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu2+ -doped and Eu2+ ,Dy3+ -co-doped Ba2 MgSi2 O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2 MgSi2 O7 :Eu2+ showed the peak to be around 381nm and 490nm respectively. The PL excitation spectrum of Ba2 MgSi2 O7 :Eu2+ Dy3+ showed the peak to be around 341nm and 388nm, and the emission spectrum had a broad band around 488nm. These emissions originated from the 4f6 5d1 to 4f7 transition of Eu2+ . TL analysis revealed that the maximum TL intensity was found at 5mol% of Eu2+ doping in Ba2 MgSi2 O7 phosphors after 15min of ultraviolet (UV) light exposure. TL intensity was increased when Dy3+ ions were co-doped in Ba2 MgSi2 O7 :Eu2+ and maximum TL intensity was observed for 2mol% of Dy3+ . TL emission spectra of Ba1.95 MgSi2 O7 :0.05Eu2+ and Ba1.93 MgSi2 O7 :0.05Eu2+ ,0.02Dy3+ phosphors were found at 500nm. TL intensity increased with UV exposure time up to 15min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co-doping. The trap depths were calculated to be 0.54eV for Ba1.95 MgSi2 O7 :0.05Eu2+ and 0.54eV and 0.75eV for Ba1.93 MgSi2 O7 :0.05Eu2+ ,0.02Dy3+ phosphors. It was observed that co-doping with small amounts of Dy3+ enhanced the thermoluminescence properties of Ba2 MgSi2 O7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f6 5d1 ', '4f7' has been corrected to '4f7 ', 'Ba1.95' has been corrected to 'Ba1.95 ' and 'Ba1.93' has been corrected to 'Ba1.93 ' respectively.].

Use of 308 nm excimer laser for the treatment of chronic hand and foot eczema.

Chronic hand and foot eczema (CHFE), a prevalent debilitating disorder affecting approximately 15% of the population, presents a socioeconomic and psychosocial burden for patients and often follows a chronic course, refractory to conventional therapies. Thus, a large need exists for more effective therapeutics; the excimer laser (308 nm) is effective for some inflammatory skin diseases, but its efficacy has not been evaluated for CHFE. The study is a retrospective chart review conducted on 30 patients with recalcitrant CHFE (19 with hand involvement, four with foot involvement, and seven with both) treated twice weekly with excimer laser (308 nm) single wavelength ultraviolet (UV)B radiation between January 2013 and December 2014. Improvements in clinical scores included a 69% reduction in average physician's global assessment (PGA) scores (from 2.77 at baseline to 0.87 after treatment, P < 0.0001) with a parallel reduction in average modified total lesion/symptom scores of 70% (from 10.2 to 3.1, P < 0.0001). Only mild sunburn-like reactions were observed. This report evaluates excimer laser for patients with refractory CHFE and shows excellent and sustained efficacy for this treatment. Compared to other UV therapies, excimer laser offers lower cumulative doses of UV radiation by targeting specific areas. This effective treatment should be considered alone or in combination with other established or newer therapies.

The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans.

Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation.

Modeling ultraviolet dose–response ofBacillusspore clusters in air

ABSTRACTThis article presents a new way to model the narrow band ultraviolet (UV-C, 254.7 nm) radiation dose–response behavior of Bacillus spores in clusters based on knowledge of the UV-C dose–response behavior of the single spores. The approach is demonstrated using experimentally obtained survival rates for Bacillus atrophaeus var. globigii (BG) spores and BG spore clusters of several sizes exposed to UV-C fluence when aerosolized and when deposited on dry surfaces. These results are modeled to derive predicted survival rates for spores in clusters of arbitrary cluster diameter under similar conditions. The essential feature of the approach is accurate accounting for attenuation of incident UV fluence within the spore cluster to derive the fluence incident on individual spores within the cluster. The results suggest that UV fluence attenuation by bacterial spores may increase with increasing fluence, a phenomenon that has not been previously reported for bacterial spores. The results are of utility in ...

Phototherapeutic modalities pose no significantly increased risk of oxidative damage to DNA in dark skinned individuals.

8-oxoguanine, a major product of DNA oxidation, is considered a key parameter in measuring the carcinogenic effects of ultraviolet radiation. To assess and compare the carcinogenic potential of different photo (chemo) therapeutic modalities in photoresponsive skin diseases by measuring the levels of 8-oxoguanine in dark-skinned individuals before and after photo (chemo) therapy. A prospective, randomized controlled pilot study was conducted in 63 patients of skin types III-V with photo-responsive dermatoses including vitiligo, psoriasis and mycosis fungoides. Patients were divided into three groups; Group 1 (received narrowband ultraviolet-B), Group 2 (received psoralen plus ultraviolet-A) and Group 3 (received broadband ultraviolet-A). Biopsies were taken before and after phototherapy to measure 8-oxoguanine levels using enzyme-linked immunosorbent assay. Biopsies were also taken from the sun-protected skin in 21 controls subjects who had no dermatological disease. Regardless of the disease, a significantly higher level of 8-oxoguanine was found after treatment when compared to the pre-treatment baseline levels; however, these levels were comparable to those in control subjects. A weakly significant positive correlation was found between cumulative dose and 8-oxoguanine levels following psoralen plus ultraviolet-A therapy. In controls, comparing the 8-oxoguanine levels between skin types III and IV showed significantly lower 8-oxoguanine in skin type IV. Therapeutic doses of ultraviolet radiation are relatively safe in dark skinned patients; however, minimizing the cumulative dose of phototherapeutic modalities (particularly psoralen plus ultraviolet-A) is recommended.

Acute Ultraviolet Radiation Perturbs Epithelialization but not the Biomechanical Strength of Full-thickness Cutaneous Wounds.

We hypothesized that priming of the skin with ultraviolet radiation (UVR) before being injured would enhance wound healing. Four groups, each comprising 20 immunocompetent hairless mice, were exposed to simulated solar irradiation in escalating UVR doses; 0 standard erythema dose (SED)=control, 1 SED, 3 SED and 5 SED. Twenty-four hours after UV irradiation, inflammation was quantified by skin reflectance (erythema) and myeloperoxidase (MPO) tissue levels, and two 6mm full-thickness excisional wounds and one 3cm incisional wound were inflicted. Epidermal hyperplasia was assessed by quantitative histology. Five days after wounding, wound coverage by neoepithelium and wound width of the excisional wounds was quantified in hematoxylin-eosin sections, and breaking strength was measured in strips from incisional wounds. Erythema (P<0.001), MPO levels (P<0.0005) and epidermal cell layers (P<0.001) increased dose-dependently by UV exposure of dorsal skin. In the excisional wounds, epithelial coverage decreased (P=0.024) by increasing the UVR dose, whereas there was no significant difference (P=0.765) in wound MPO levels. Neither wound width (P=0.850) nor breaking strength (P=0.320) differed among the groups. Solar-simulated UVR 24h before wounding impaired epithelialization but was not detrimental for surgical incisional wound healing.

Oxidative stress in Microcystis aeruginosa as a consequence of global climate change

Cyanobacteria are phototrophic organisms with great ecological and economical importance. Species of the genus Microcystis are known for their potential ability to synthesize toxins, notably microcystins. There is a growing interest in the evaluation of oxidative stress in relation to the impact of global climate change on natural ecosystems in different trophic levels. Several studies have focused on the analysis of organismal responses to mitigate the damage by controlling the generation of reactive oxygen species. Variations in environmental factors caused by climate change generate a situation of oxidative damage in Microcystis aeruginosa as a direct or indirect consequence. In this study we evaluate the effects of ultraviolet radiation and temperature on physiological and biochemical responses of a native M. aeruginosa (strain CAAT 2005-3). The results from the exposure to ultraviolet radiation doses and temperature changes suggest a high ability of M. aeruginosa to detect a potential stress situation as a consequence of reactive species production and to rapidly initiate antioxidant defenses. Increased catalase activity is an antioxidant protection mechanism in M. aeruginosa for short and long term exposure to different changes in environmental conditions. However, we found a ultraviolet-B radiation threshold dose above which oxidative stress exceeds the antioxidant protection and damage occurs. In addition our results are in agreement with recent findings suggesting that microcystins may act as protein-modulating metabolites and protection against reactive oxygen species. It is concluded that cyanobacteria have adaptative mechanisms that could lead to the replacement of species highly susceptible to oxidative stress by others with a higher system of antioxidant protection.

Mitochondria can orchestrate sex differences in cell fate of vascular smooth muscle cells from rats.

BackgroundIn basal conditions, vascular smooth muscle cells freshly isolated from aortas of male and female rats display marked sex differences in terms of redox balance and susceptibility to ultraviolet radiation-induced cell death. In particular, in the same experimental conditions, cells from male rats are more susceptible to oxidative stress and underwent apoptosis, while cells from female rats underwent premature senescence. In the present work, the mechanism involved in cell fate after ultraviolet radiation exposure is investigated.MethodsVascular smooth muscle cells, isolated from the descending aortas of both female and male Sprague–Dawley young rats, were exposed to a single sub-cytotoxic dose of ultraviolet radiation (200 mJ/cm2). The distribution and the expression of molecules involved in cell survival and mitochondrial physiology were evaluated by static and flow cytometry using commercial kits and antibodies. Statistical analyses were performed by using Student’s t test and two-way ANOVA.ResultsAfter exposure to ultraviolet radiation, an upregulation of survival proteins such as BclxL, survivin and the presence in the nucleus of NF-κB were found in cells from females. Conversely, pro-apoptotic proteins such as Bax, caspase-3, and caspase-9 as well as loss of mitochondrial membrane potential were found in cells from male rats.ConclusionsOur results suggest that (i) mitochondria, being producers of ROS, can orchestrate sex differences in cell fate of VSMC and (ii) mitochondrial dysfunction may be a significant mechanism by which cardiovascular risk factors lead to the formation of vascular lesions in a sex-specific way.

Skin tumor development after UV irradiation and photodynamic therapy is unaffected by short-term pretreatment with 5-fluorouracil, imiquimod and calcipotriol. An experimental hairless mouse study

BackgroundPhotodynamic therapy (PDT) delays ultraviolet (UV) radiation-induced squamous cell carcinomas (SCCs) in hairless mice. Efficacy may be enhanced by combining PDT with antineoplastic or pro-differentiating agents. We investigated if pretreatment with 5-fluorouracil (5FU), imiquimod (IMIQ) or calcipotriol (CAL) before PDT further delays tumor onset. MethodsHairless mice (n=224) were exposed 3 times weekly to 3 standard erythema doses (SED) of UV radiation. Methyl-aminolevulinate (MAL)-PDT sessions were given on days 45 and 90 before SCC development. Three applications of topical 5FU, IMIQ or CAL were given before each PDT session. Fluorescence photography quantified protoporphyrin IX (PpIX) formation. ResultsPDT delayed UV-induced SCC development by 59days (212days UV-MAL-PDT vs. 153days UV-control, P<0.001). Pretreatment with 5FU, IMIQ or CAL before PDT did not further delay SCC onset compared to PDT alone (207days UV-5FU-MAL-PDT, 215days UV-IMIQ-MAL-PDT, 206days UV-CAL-MAL-PDT vs. 212days UV-MAL-PDT, P=ns). PpIX fluorescence intensified by 5FU-pretreatment (median 21,392au UV-5FU-MAL-PDT, P=0.011), decreased after IMIQ-pretreatment (12,452au UV-IMIQ-MAL-PDT, P<0.001), and was unaffected by CAL-pretreatment (19,567au UV-CAL-MAL-PDT, P=ns) compared to MAL alone (18,083au UV-MAL-PDT). ConclusionsShort-term three-day pretreatment with 5FU, IMIQ and CAL before PDT does not further delay tumor onset in UV-exposed hairless mice.

Effects of ultraviolet radiation on properties of films from whey protein concentrate treated before or after film formation

Properties (water vapour permeability, solubility in water, colour, mechanical properties and microstructure) of whey protein concentrate films treated with ultraviolet radiation were evaluated.Ultraviolet treatments at different doses (0.12, 4.0 and 12.0 J cm−2) were applied to film-forming solution or to preformed films. These films were compared to untreated films and heat treated films (from solutions subjected to heat treatment). Besides, some structural changes induced to proteins (free sulfhydryl groups, degree of aggregation and denaturation and secondary structure) by radiation have also been investigated.Ultraviolet treatment only affected significantly most mechanical properties and solubility when was applied to film-forming solution and at the highest dose. These films showed significantly higher tensile strength, puncture strength and puncture deformation and lower solubility than untreated films. Films treated with the highest dose of ultraviolet radiation in solution showed tensile strength similar to heat-treated films. Ultraviolet radiation caused that the films were more yellow, greener and darker than untreated films, although the effect of the treatment on colour was higher when was applied to the film-forming solution. Ultraviolet radiation of solutions at high doses increased the concentration of free sulfhydryl groups and induced aggregates formation comparing to untreated films but the changes were lower than those observed in heat-treated films; the denaturation was higher in α-lactalbumin than in β-lactoglobulin. No changes in the secondary structure of proteins were detected. Differences in microstructure were found among films. According to the results, ultraviolet radiation modifies the properties of the films and in different way that heat treatment.

Maximum Incident Erythemally Effective UV Exposure Received by Construction Workers, in Valencia, Spain.

This article analyzes the influence of Ultraviolet Erythematic Radiation (UVER) dose received by construction workers in Valencia highlighting the upper limit of the dose received for a worker in different periods of a year. Building construction usually implies workers to stand for several hours outdoors while working until roof top is finished. In Valencia, construction carried out near the coastline has been very intense in the last few years with the construction of a great amount of summer flats. This article focuses on the maximum values UVER can reach in different seasons of the year for cities with similar latitude to Valencia (39°28'N, 0°22'W), as an important way of warning construction workers about the necessity of taking preventive actions. Viospor dosimeters placed on a mannequin have been used in this study. The measurements took place between 2012 December and 2013 July.

Low doses of ultraviolet radiation and oxidative damage induce dramatic accumulation of mitochondrial DNA replication intermediates, fork regression, and replication initiation shift.

Mitochondrial DNA is prone to damage by various intrinsic as well as environmental stressors. DNA damage can in turn cause problems for replication, resulting in replication stalling and double-strand breaks, which are suspected to be the leading cause of pathological mtDNA rearrangements. In this study, we exposed cells to subtle levels of oxidative stress or UV radiation and followed their effects on mtDNA maintenance. Although the damage did not influence mtDNA copy number, we detected a massive accumulation of RNA:DNA hybrid-containing replication intermediates, followed by an increase in cruciform DNA molecules, as well as in bidirectional replication initiation outside of the main replication origin, OH. Our results suggest that mitochondria maintain two different types of replication as an adaptation to different cellular environments; the RNA:DNA hybrid-involving replication mode maintains mtDNA integrity in tissues with low oxidative stress, and the potentially more error tolerant conventional strand-coupled replication operates when stress is high.

A randomized controlled trial of green tea catechins in protection against ultraviolet radiation–induced cutaneous inflammation

Background: Safe systemic protection from the health hazards of ultraviolet radiation (UVR) in sunlight is desirable. Green tea is consumed globally and is reported to have anti-inflammatory properties, which may be mediated through the impact on cyclooxygenase and lipoxygenase pathways. Recent data suggest that green tea catechins (GTCs) reduce acute UVR effects, but human trials examining their photoprotective potential are scarce.Objective: We performed a double-blind, randomized, placebo-controlled trial to examine whether GTCs protect against clinical, histologic, and biochemical indicators of UVR-induced inflammation.Design: Healthy adults (aged 18–65 y, phototypes I–II) were randomly allocated to 1350 mg encapsulated green tea extract (540 mg GTC) with 50 mg vitamin C or placebo twice daily for 3 mo. Impact on skin erythema, dermal leukocytic infiltration, and concentrations of proinflammatory eicosanoids was assessed after solar-simulated UVR challenge, and subject compliance was determined through assay of urinary GTC metabolite epigallocatechin glucuronide.Results: Volunteers were assigned to the active (n = 25) or the placebo (n = 25) group. After supplementation, median (IQR) sunburn threshold (minimal erythema dose) was 28 (20–28) and 20 (20–28) mJ/cm2 in the active and placebo groups, respectively (nonsignificant), with no difference in AUC analysis for measured erythema index after a geometric series of 10 UVR doses. Skin immunohistochemistry showed increased neutrophil and CD3+ T-lymphocyte numbers post-UVR in both groups (P < 0.01) with no statistically significant differences between groups after supplementation. Cyclooxygenase and lipoxygenase metabolites prostaglandin E2 (vasodilator) and 12-hydroxyeicosatetraenoicacid (chemoattractant), respectively, increased after UVR (P < 0.05), with no differences between supplementation groups.Conclusion: Oral GTC (1080 mg/d) with vitamin C over 3 mo did not significantly reduce skin erythema, leukocyte infiltration, or eicosanoid response to UVR inflammatory challenge. This trial was registered at clinicaltrials.gov as NCT01032031.

Sun behaviour and personal UVR exposure among Europeans on short term holidays

Solar ultraviolet radiation (UVR) is known to be the main cause of skin cancer, the incidence of which is rising with national differences across Europe. With this observation study we aimed to determine the impact of nationality on sun behaviour and personal UVR exposure on sun and ski holidays. 25 Danish and 20 Spanish sun-seekers were observed during a sun holiday in Spain, and 26 Danish and 27 Austrian skiers were observed during a ski holiday in Austria. The participants recorded their location and clothing in diaries. Personal time-logged UVR data were recorded as standard erythema doses (SEDs) by an electronic UVR dosimeter worn on the wrist. Danish sun-seekers were outdoors for significantly longer, received significant higher percentages of ambient UVR, and received greater accumulated UVR doses than Spanish sun-seekers. Danish skiers were also outdoors for significantly longer than Austrian skiers, but the behaviour of the Danish skiers did not result in significantly greater accumulated UVR doses. Both Danish and Spanish sun-seekers and Danish and Austrian skiers received substantial UVR doses. The behaviour’s influence on the UVR doses received by the Danish participants may indicate an explanation of the higher skin cancer incidence among Scandinavians compared with other European populations.

Skin Cancers as Contraindication to Organ Transplantation

The period of preparing patients for organ transplantation is a suitable time for dermatologic screening and examination that guarantee early diagnosis and easier treatment of precancerous states and skin cancers. In most cases, diagnosis of skin cancer in the pretransplantation period is not a contraindication to transplantation. Knowledge of risk factors and etiopathogenesis of skin cancers after transplantation make it easier to point out patients with increased risk of skin carcinogenesis. Patients with skin phototype I–III (Fitzpatrick classification) and with high cumulative doses of ultraviolet radiation have an increased risk of skin cancers. Patients who had skin cancers in the past should be carefully examined, and the skin cancer histopathology should be analyzed in detail. These examinations have to be done from the clinical, surgical, and histopathologic aspects. It helps dermatologists to estimate the risk and predict the patient's health after a possible organ transplantation. Basal cell carcinoma and squamous cell carcinoma that are present before transplantation indicate the possibility of similar cancer occurrence after transplantation; however, they are not a contraindication to transplantation after treatment of the primary foci. The waiting period to transplantation in the case of melanoma in situ takes 2 years, but in more serious forms of melanoma this time is prolonged to ≥5–10 years. Different skin cancers have a 3-year asymptomatic period to renewed indication for transplantation.

Evaluation of Cutaneous Damage and Repair Following Acute Solar Ultraviolet Radiation Exposure: Experiments with anIn VitroReconstructed Human Skin Model and Excised Human Skin

Abstract Overexposure of human skin to solar ultraviolet radiation (UVR) is known to produce deleterious effects including cutaneous photoaging and cancers. The present studies were conducted to confirm the utility of a commercially available full-thickness reconstructed human skin model (EpiDermFT) for reproducing tissue and cellular effects involved in cutaneous responses to acute solar UVR exposure. EpiDermFT tissues were irradiated with a single acute UVR dose approximately equivalent to either 6 or 9.5 minimal erythemal doses. Cutaneous damage and recovery were then monitored for a period of 7 days. Excised human skin specimens were treated under identical conditions for comparison. The UVR exposures resulted in pronounced structural and morphological alterations in both the EpiDermFT and excised skin tissues. Both models demonstrated a similar timecourse of sunburn cell (SBC) formation, epidermal necrosis, acantholysis and parakeratosis, and regeneration. The EpiDermFT model also reproduced key aspe...

New approach for a reliable in vitro sun protection factor method Part I: Principle and mathematical aspects.

Development of an international harmonized in vitro method for sun protection factor (SPF) assessment is currently in progress because of the lack of both reproducibility and accuracy in the current methodology. The aim of this article was to focus on the principle and mathematical aspects (Part I) of a new approach for a reproducible and correlated in vitro test method to obtain results similar to the in vivo SPF for labelling purposes. The currently used in vitro test is based on the spectroradiometric measurement of the residual ultraviolet (UV) transmitted through a thin layer of sunscreen spread on a substrate. To reach the goals of reproducibility and accuracy, the specifications of the key parameters and different steps of the procedure are clearly described in this study. Once reproducibility is obtained with an ad hoc procedure, the accuracy of the SPF values for a large number of products can be demonstrated with the prerequisite of a single UV irradiation dose and a multisubstrate solution. Using a total of 27 samples, the mean coefficient of variation was found to be <10% and the coefficient of correlation with the SPF clinical value reached approximately 0.81. The first part of the article revealed a relevant tool for the in vitro SPF assessment that can be closely correlated to the in vivo SPF for labelling purposes. The second part study will focus on the practical aspects and implementation (Part II) achieved using the present method, will validate the robustness of the models and demonstrate the need to have different product categories to reach a reliable in vitro SPF method adaptable for all products available in the market.

Isolation and characterization of a novel strain of genus Dietzia capable of multiple-extreme resistance

An ultraviolet (UV) radiation resistant gram-positive bacterium, Dietzia sp. MG4 strain, was isolated from the Sirch Hot Spring (Kerman, Iran), then it was identified on the basis of morphological and biochemical characteristics, and 16S rRNA gene sequencing. The effects of temperature, pH, desiccation, different percentage of NaCl, hydrogen peroxide (H2O2), mitomycin C (MMC) and high levels of radiation on viability or growth rate of MG4 strain were investigated. Also heavy metal tolerance of MG4 strain was assayed. 16S rDNA sequence of the isolate exhibited 99.69% similarity with Dietzia sp. and this result was confirmed by phylogenetic analysis. Viability of this strain was obtained D91 according to D index after exposure to 25 J/cm2 UV radiation dose, and D30 after desiccation stress (for 28 days) using flow cytometery. The D10 value for a microorganism is defined as the stress dose necessary to provide 10% survivors. Therefore, this strain showed high resistance to UV-C radiation and moderate resistance to desiccation. Optimal growth of MG4 strain was observed at pH 9, temperature of 30°C and 5% (w/v) NaCl. Isolated Dietzia was resisted up to 3 mM of nickel and 0.2 mM of mercury ions. Also this strain could tolerate 1–4% (v/v) H2O2 and 8 µg/mL of MMC as oxidant agents. To the best of our knowledge, this is the first study on multiple extreme resistant Dietzia sp. MG4 strain.

A potential role for endogenous proteins as sacrificial sunscreens and antioxidants in human tissues

Excessive ultraviolet radiation (UVR) exposure of the skin is associated with adverse clinical outcomes. Although both exogenous sunscreens and endogenous tissue components (including melanins and tryptophan-derived compounds) reduce UVR penetration, the role of endogenous proteins in absorbing environmental UV wavelengths is poorly defined. Having previously demonstrated that proteins which are rich in UVR-absorbing amino acid residues are readily degraded by broadband UVB-radiation (containing UVA, UVB and UVC wavelengths) here we hypothesised that UV chromophore (Cys, Trp and Tyr) content can predict the susceptibility of structural proteins in skin and the eye to damage by physiologically relevant doses (up to 15.4J/cm2) of solar UVR (95% UVA, 5% UVB). We show that: i) purified suspensions of UV-chromophore-rich fibronectin dimers, fibrillin microfibrils and β- and γ-lens crystallins undergo solar simulated radiation (SSR)-induced aggregation and/or decomposition and ii) exposure to identical doses of SSR has minimal effect on the size or ultrastructure of UV chromophore-poor tropoelastin, collagen I, collagen VI microfibrils and α-crystallin. If UV chromophore content is a factor in determining protein stability in vivo, we would expect that the tissue distribution of Cys, Trp and Tyr-rich proteins would correlate with regional UVR exposure. From bioinformatic analysis of 244 key structural proteins we identified several biochemically distinct, yet UV chromophore-rich, protein families. The majority of these putative UV-absorbing proteins (including the late cornified envelope proteins, keratin associated proteins, elastic fibre-associated components and β- and γ-crystallins) are localised and/or particularly abundant in tissues that are exposed to the highest doses of environmental UVR, specifically the stratum corneum, hair, papillary dermis and lens. We therefore propose that UV chromophore-rich proteins are localised in regions of high UVR exposure as a consequence of an evolutionary pressure to express sacrificial protein sunscreens which reduce UVR penetration and hence mitigate tissue damage.

Weekend personal ultraviolet radiation exposure in four cities in Australia: Influence of temperature, humidity and ambient ultraviolet radiation

PurposeTo examine the effects of meteorological factors on weekend sun exposure behaviours and personal received dose of ultraviolet radiation (UVR) in Australian adults. MethodsAustralian adults (n=1002) living in Townsville (19°S, 146°E), Brisbane (27°S, 153°E), Canberra (35°S, 149°E) and Hobart (43°S, 147°E) were recruited between 2009 and 2010. Data on sun exposure behaviours were collected by daily sun exposure dairies; personal UVR exposure was measured with a polysulphone dosimeter. Meteorological data were obtained from the Australian Bureau of Meteorology; ambient UVR levels were estimated using the Ozone Monitoring Instrument data. ResultsHigher daily maximum temperatures were associated with reduced likelihood of wearing a long-sleeved shirt or wearing long trousers in Canberra and Hobart, and higher clothing-adjusted UVR dose in Canberra. Higher daily humidity was associated with less time spent outdoors in Canberra. Higher ambient UVR level was related to a greater clothing-adjusted personal UVR dose in Hobart and a greater likelihood of using sunscreen in Townsville. ConclusionThe current findings enhance our understanding of the impact of weather conditions on the population’s sun exposure behaviours. This information will allow us to refine current predictive models for UVR-related diseases, and guide future health service and health promotion needs.