UVB Exposure Research Articles

Two Iranian Scrophularia striata Boiss. ecotypes under UV-B radiation: Germination and initial growth perspective

Concerning the increasing level of ultraviolet (UV) radiation in many parts of the world, researching plant establishment under UV exposure is an essential subject. This experiment was aimed at exploring the effects of UV-B on the germination rate, seedling length, radix and stem's length, seedling's fresh/dry weight, and germination indices of Scrophularia striata seeds (Scrophulariaceae), a native medicinal plant from Iran. Treatments included UV-B exposure times (0/control, 15, 30, and 45 min) on two different ecotypes of S. striata including Lizan (LE) and Pahleh (PE). The UV-B radiation treatment for 45 min significantly enhanced the final germination percentage (FGP) of PE seeds. Maximum TSG (time spread of germination) was achieved under 45 min UV exposure (3.67 Day) in PE, while in LE, increasing radiation caused a significant reduction in TSG. Regarding principle component analysis, PE showed better germination indices under UV-B radiation. The seedling length of S. striata was remarkably changed by UV-B treatment; in this case, enhanced seedling length was observed in LE than PE. The UV-B exposure can have promotive effects on many important germination indices in seeds and some seedling growth parameters in S. striata ecotypes, and this effect could be related to the ecotype differences and ecotype-specific responses.

Combination of acitretin and narrowband UV-B for the treatment of vitiligo: A new treatment modality with an impact on tissue E-cadherin expression

Combination of acitretin and narrowband UV-B for the treatment of vitiligo: A new treatment modality with an impact on tissue E-cadherin expression

A novel circRNA, circRACGAP1, hampers the progression of systemic lupus erythematosus via miR-22-3p-mediated AKT signalling

Background Systemic lupus erythematosus (SLE) is defined as a multisystem autoimmune disease involving various organs, of which exact molecular mechanisms remain elusive. Here, we aimed to investigate a novel circular RNA (circRNA), circRACGAP1, abnormally expressed in SLE and explored its underlying regulatory network. Methods The expression patterns of circRACGAP1 were determined in patients diagnosed with SLE by using a qRT-PCR assay. Spearman correlation analysis was employed to evaluate the correlation between circRACGAP1 and clinicopathological variables in patients with SLE. Flow cytometry and TUNEL assays were subjected to assess the cell apoptosis. Nuclear-cytoplasmic fractionation and luciferase reporter assay was used to verify the circRACGAP1/miR-22-3p/PTEN axis. Western blot analysis was performed to measure the PTEN/AKT signalling-related proteins and apoptotic-related biomarkers. Results Down-regulated circRACGAP1 was observed and correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score, anti-double-stranded (ds) DNA, and complement C3 level in patients with SLE. Overexpression of circRACGAP1 significantly alleviated cell apoptosis in Jurkat cells within UVB exposure. Mechanistic investigation revealed that circRACGAP1 could serve as a sponge of miR-22-3p to regulate PTEN/AKT signalling. Conclusions Collectively, circRACGAP1 regulated the AKT signalling pathway via binding to miR-22-3p in the progression of SLE, suggesting therapeutic targets for SLE treatment.

Inhibition of Fibroblast Growth Factor Receptor Attenuates UVB-Induced Skin Carcinogenesis

Altered fibroblast GF receptor (FGFR) signaling has been shown to play a role in a number of cancers. However, the role of FGFR signaling in the development and progression of UVB-induced cutaneous squamous cell carcinoma remains unclear. In this study, the effect of UVB radiation on FGFR activation and its downstream signaling in mouse skin epidermis was examined. In addition, the impact of FGFR inhibition on UVB-induced signaling and skin carcinogenesis was also investigated. Exposure of mouse dorsal skin to UVB significantly increased the phosphorylation of FGFRs in the epidermis as well as the activation of downstream signaling pathways, including protein kinase B/mTOR, signal transducers and activators of transcription, and MAPK. Topical application of the pan-FGFR inhibitor AZD4547 to mouse skin before exposure to UVB significantly inhibited FGFR phosphorylation as well as mTORC1, signal transducer and activator of transcription 3, and MAPK activation (i.e., phosphorylation). Moreover, AZD4547 pretreatment significantly inhibited UVB-induced epidermal hyperplasia and hyperproliferation and reduced the infiltration of mast cells and macrophages into the dermis. AZD4547 treatment also significantly inhibited mRNA expression of inflammatory genes in the epidermis. Finally, mice treated topically with AZD4547 before UVB exposure showed decreased cutaneous squamous cell carcinoma incidence and increased survival rate. Collectively, the current data support the hypothesis that inhibition of FGFR in the epidermis may provide a new strategy to prevent and/or treat UVB-induced cutaneous squamous cell carcinoma.

Effects of UV-B and Water Deficit on Aroma Precursors in Grapes and Flavor Release during Wine Micro-Vinification and Consumption.

UV-B radiation and water availability can affect amino acids(AAs) concentration in berries, resulting in the evolution of aroma compounds during alcoholic fermentation. This study investigated the effects of UV-B exposure and water availability onwine aroma compounds in Pinot noir, focusing on the role of AAs in the process.Enhanced UV-B radiation significantly decreased total AA concentrations and most individual AAs inberries and wines, while water deficitincreased some individual AAsin wines. Higher alcohols, fatty acids, esters, monoterpenes, and C13-norisoprenoids were affected by UV-B interaction with water deficit in wines. These results suggested individual or combined UV-B exposure and water deficit had direct effects on fruit AAs, leading to significant differences in some wine aroma compounds.

Studying the effects of suberythemal UV doses on the human stratum corneum by in vivo confocal Raman spectroscopy

The stratum corneum (SC) plays an important role in skin barrier function. It acts as a protective barrier against water loss, eliminates foreign substances and micro-organisms and acts against harmful effects of UVR. Our aim was to study the impact of suberythemal doses of UVA and UVB exposure on the molecular structure, organization and barrier function of the SC by following different Raman descriptors. Twenty female volunteers, aged 20-30 years, with healthy skin were enrolled. Doses of 95 mJ/cm²UVA and 15 mJ/cm²UVB were applied to volunteers’ forearms. In vivo Raman measurements were performed at irradiated and control regions. The impact of UVA and UVB irradiation was observed following several Raman descriptors, i.e. the ratio of vasymCH2/vsymCH2 (2885 cm-1/2850 cm-1) corresponding to the organizational order of the lipid bilayer. Water content and mobility descriptors were obtained by calculating vOH/vCH ratio. Finally, protein secondary structure was evaluated based on the 1670 cm-1/1650 cm-1ratio related to β sheets and α helices, respectively. UVA induced a loosening of the lateral packing of lipids immediately after irradiation. In contrast, delayed impact caused a tightening of the lipid barrier, an increase in water content -mainly in the unbound water fraction and a higher relative amount of β sheets in SC proteins. Overall, these observations may explain the thickening of the SC observed in previous studies. A UVB dose of 15 mJ/cm²was apparently below the threshold necessary to induce significant changes despite the trends observed in this study.

Health-Promoting Phenolic Compound Accumulation, Antioxidant Response, Endogenous Salicylic Acid Generation, and Biosynthesis Gene Expression in Germinated Pigeon Pea Seeds Treated with UV-B Radiation.

Germinated pigeon pea seeds (GPPSs) are good dietary supplements with satisfactory nutritional and medicinal values. In this study, UV-B treatment was used to promote the accumulation of health-promoting phenolic compounds (10 flavonoids and 1 stilbene) in GPPS. The total yield of 11 phenolic compounds (235 839.76 ± 17 118.24 ng/g DW) significantly improved (2.53-fold increase) in GPPSs exposed to UV-B radiation (3 W/m2) for 8 h, whereas free amino acid and reducing sugar contents exhibited a decreasing tendency during UV-B exposure. Meanwhile, the positive response in the antioxidant activities of enzymes and nonenzymatic extracts was noticed in UV-B-treated GPPSs. Moreover, UV-B radiation could cause tissue damages in hypocotyls and cotyledons of the GPPSs and enhance the generation of endogenous salicylic acid, thus activating the expression of biosynthesis genes (especially CHS and STS1). Overall, the simple UV-B supplementation strategy makes GPPSs more attractive as functional foods/nutraceuticals in diet for promoting human health.

In vivo anti-inflammatory and antioxidant effects of microbial polysaccharides extracted from Euganean therapeutic muds

Therapeutic thermal mud produced by spas of the Euganean Thermal District (Italy) is used as a treatment for arthro-rheumatic diseases. Its production involves the growth of a specific microbiota embedded in a polysaccharidic matrix. Polysaccharides (Microbial-PolySaccharides, M-PS) released in the mud by the resident microorganisms were extracted and analyzed. The monosaccharidic composition analysis showed the presence of galacturonic acid, mannose, xylose, ribose and glucose and a high percentage of sulfated groups in the polymers. To assess their involvement in the therapeutic efficacy of the mud, the M-PS were tested using the model organism zebrafish (Danio rerio). The anti-inflammatory and antioxidant activities were evaluated after confirming the lack of toxic effects during development. Inflammatory state was induced chemically with copper sulfate, or through tail fin amputation procedure and UVB exposure. Recovery from inflammatory condition after exposure to M-PS was always observed with specific morphometric analyses, and further supported by qPCR. Genes linked with the inflammatory and oxidative stress response were investigated confirming the M-PS treatment's efficacy.

Analysis of the effects of UVB radiation on bone density and behavior of hatchling false water cobras, Hydrodynastes gigas.

In herpetoculture, there is debate as to whether ultraviolet-B, UVB, lighting is required for providing adequate welfare for snakes in human care. Many believe this supplemental lighting is unnecessary and is not utilized by the snakes, stating that snakes survive and breed in its absence. Previous studies using pythons and corn snakes have demonstrated that offering UVB lighting appears to have a significant effect on their physiology. These studies focused on the increase of 25-hydroxyvitamin D3 concentrations in the blood after UVB exposure. In the present study, false water cobras, Hydrodynastes gigas, were chosen because they are active, diurnal snakes and are therefore more likely to seek out UVB in the wild in comparison with other fossorial snakes. The level of UVB that will be provided is based on the tropical climate of the range for H. gigas. Twelve hatchling H. gigas will be divided into two groups with Arcadia T5 14% UVB lights provided for one group and LED lights provided for the other. The behavior of the snakes will be monitored through video recording to determine the effects of UVB lighting on basking behavior and total time exposed to the UVB lighting. To identify physiological effects, radiographs will be taken to determine any change in bone density. This study aims to find if offering UVB lighting promotes basking behavior and affects bone density in H. gigas. The results of this study can be used to further increase welfare standards for snakes in captivity.

Age-Defying and Photoprotective Potential of Geranium/Calendula Essential Oil Encapsulated Vesicular Cream on Biochemical Parameters against UVB Radiation Induced Skin Aging in Rat

UVB irradiation promotes the production of reactive oxygen species, which can lead to an increase in oxidative stress in the cell and the generation of toxic components, resulting in photoaging. Essential oils (EOs) are well-known in the cosmetics sector for their beneficial effects, as they have a wide range of biological activities. Considering this fact, the current study investigates the photoprotective potential of geranium essential oil (GEO)/calendula essential oil (CEO) encapsulated vesicular cream on the biochemical parameters of the skin of albino rats exposed to UVB radiation. After 30 days of treatment with cream formulations and UVB irradiation, the skin tissue was assayed for several biochemical parameters and histopathology analysis. The results of biochemical study revealed that, in comparison to non-vesicular creams, vesicular cream formulations were able to protect the endogenous skin natural antioxidant system by maintaining superoxide dismutase, catalase, total protein, ascorbic acid, and hydroxyproline levels and by decreasing malondialdehyde levels in the skin after UVB exposure. Changes in various cellular structures along with the change in the epidermis and dermis of the skin after UVB exposure in the treated group were observed by a histopathology of skin tissue and compared to the non-treated group, which revealed the skin damaging effect of UVB radiation and the protective effect of vesicular creams. The results suggest that the GEO/CEO-encapsulated vesicular creams have the potential to protect the skin against harmful UVB radiation by maintaining the natural antioxidant defence mechanism of the skin. In conclusion, this research presents novel herbal cosmetic formulations with improved antioxidant capacity and photoprotective potential that may help to slow down the skin aging process.

Tunning self-assembled phases of bovine serum albumin via hydrothermal process to synthesize novel functional hydrogel for skin protection against UVB

Abstract Ultraviolet rays – B (UVB) can be efficiently absorbed by the cellular molecules of skin inducing damage within skin cells and a major cause of melanoma cancer. In recent years, several studies have reported the adverse effects of traditionally used organic and inorganic material-based sunscreens and UVB blockers. In this study, bovine serum albumin (BSA) has been used as a precursor to synthesize temperature- and pressure-dependent phase transition from sol (globular aggregates) – gel (hydrogels) – sol (carbon quantum dots) using a single-step hydrothermal method with an objective to develop an efficient and effective UVB blocker. The synthesized hydrogels exhibit UV – attenuation, self-fluorescence, and high biocompatibility properties that make them a suitable candidate for UV-blocker or sunscreen material. The biological efficacy of the hydrogels was studied through cyto-toxicity studies. Also, UVB blocking efficiency of developed hydrogel in primary mice skin cell culture as well as in vivo in mice model was studied. In vivo study on mice further demonstrated prominent thickening of stratum corneum and epidermis with perivascular edema in the dermis after 5 days of UVB exposure. Hence, this suggesting that hydrogel could be a potential candidate for protecting the skin from UVB exposure and reducing the threat of skin cancer.

Production of Microsclerotia by Metarhizium sp., and Factors Affecting Their Survival, Germination, and Conidial Yield.

Microsclerotia (MS) produced by some species of Metarhizium can be used as active ingredients in mycoinsecticides for the control of soil-dwelling stages of geophilic pests. In this study, the MS production potential of two Metarhizium brunneum strains and one M. robertsii strain was evaluated. The three strains were able to produce MS in liquid fermentation, yielding between 4.0 × 106 (M. robertsii EAMa 01/158-Su strain) and 1.0 × 107 (M. brunneum EAMa 01/58-Su strain) infective propagules (CFU) per gram of MS. The EAMa 01/58-Su strain was selected for further investigation into the effects of key abiotic factors on their survival and conidial yield. The MS were demonstrated to be stable at different storage temperatures (−80, −18, and 4 °C), with a shelf-life up to one year. The best temperature for MS storage was −80 °C, ensuring good viability of MS for up to one year (4.9 × 1010 CFU/g MS). Moreover, soil texture significantly affected CFU production by MS; sandy soils were the best driver of infective propagule production. Finally, the best combination of soil temperature and humidity for MS germination was 22.7 °C and 7.3% (wt./wt.), with no significant effect of UV-B exposure time on MS viability. These results provide key insights into the handling and storage of MS, and for decision making on MS dosage and timing of application.

Association of Latitude and Exposure to Ultraviolet B Radiation With Severity of Multiple Sclerosis: An International Registry Study.

The severity of multiple sclerosis (MS) varies widely among individuals. Understanding the determinants of this heterogeneity will help clinicians optimize the management of MS. The aim of this study was to investigate the association between latitude of residence, UV B radiation (UVB) exposure, and the severity of MS. This observational study used the MSBase registry data. The included patients met the 2005 or 2010 McDonald diagnostic criteria for MS and had a minimum dataset recorded in the registry (date of birth, sex, clinic location, date of MS symptom onset, disease phenotype at baseline and censoring, and ≥1 Expanded Disability Status Scale score recorded). The latitude of each study center and cumulative annualized UVB dose at study center (calculated from National Aeronautics and Space Administration's Total Ozone Mapping Spectrometer) at ages 6 and 18 years and the year of disability assessment were calculated. Disease severity was quantified with Multiple Sclerosis Severity Score (MSSS). Quadratic regression was used to model the associations between latitude, UVB, and MSSS. The 46,128 patients who contributed 453,208 visits and a cumulative follow-up of 351,196 patient-years (70% women, mean age 39.2 ± 12 years, resident between latitudes 19°35' and 56°16') were included in this study. Latitude showed a nonlinear association with MS severity. In latitudes <40°, more severe disease was associated with higher latitudes (β = 0.08, 95% CI 0.04-0.12). For example, this translates into a mean difference of 1.3 points of MSSS between patients living in Madrid and Copenhagen. No such association was observed in latitudes <40° (β = -0.02, 95% CI -0.06 to 0.03). The overall disability accrual was faster in those with a lower level of estimated UVB exposure before the age of 6 years (β = - 0.5, 95% CI -0.6 to 0.4) and 18 years (β = - 0.6, 95% CI -0.7 to 0.4), as well as with lower lifetime UVB exposure at the time of disability assessment (β = -1.0, 95% CI -1.1 to 0.9). In temperate zones, MS severity is associated with latitude. This association is mainly, but not exclusively, driven by UVB exposure contributing to both MS susceptibility and severity.

Arabidopsis mediator subunit 17 connects transcription with DNA repair after UV-B exposure.

Mediator 17 (MED17) is a subunit of the Mediator complex that regulates transcription initiation in eukaryotic organisms. In yeast and humans, MED17 also participates in DNA repair, physically interacting with proteins of the nucleotide excision DNA repair system, but this function in plants has not been investigated. We studied the role of MED17 in Arabidopsis plants exposed to UV-B radiation. Our results demonstrate that med17 and OE MED17 plants have altered responses to UV-B, and that MED17 participates in various aspects of the DNA damage response (DDR). Comparison of the med17 transcriptome with that of wild-type (WT) plants showed that almost one-third of transcripts with altered expression in med17 plants were also changed by UV-B exposure in WT plants. Increased sensitivity to DNA damage after UV-B in med17 plants could result from the altered regulation of UV-B responsive transcripts but MED17 also physically interacts with DNA repair proteins, suggesting a direct role of this Mediator subunit during repair. Finally, we show that MED17 is necessary to regulate the DDR activated by ataxia telangiectasia and Rad3 related (ATR), and that programmed cell death 5 (PDCD5) overexpression reverts the deficiencies in DDR shown in med17 mutants. Our data demonstrate that MED17 is an important regulator of DDR after UV-B irradiation in Arabidopsis.

Ultraviolet-B Radiation Represses Primary Root Elongation by Inhibiting Cell Proliferation in the Meristematic Zone of Arabidopsis Seedlings.

In Arabidopsis thaliana plants, exposure to UV-B induces an inhibition of primary root elongation. Different mutants have been isolated that are deficient in this response; however, little is known about the cellular and molecular mechanisms that regulate inhibition of root elongation in seedlings exposed to UV-B. In this work, we investigated the effect UV-B irradiation of different organs on primary root elongation. Our results demonstrate that irradiation of the leaves and shoots only induce a partial inhibition of primary root elongation, while when only roots are exposed to this radiation, primary root inhibition is similar as that measured when the complete seedling is irradiated. The consequences of exposure at different root developmental stages and times after the end of the treatment was also studied. We here show that inhibition of primary root elongation is a consequence of a decrease in cell proliferation in the meristematic zone of the primary roots, while the elongation zone size is not affected by the treatment. The decrease in cell number after UV-B exposure is partially compensated by an increase in cell length in the root meristem; however, this compensation is not enough to maintain the meristem size. We also here demonstrate that, similarly as what occurs in developing leaves, GROWTH REGULATING FACTOR 3 (GRF3) transcription factor regulates cell proliferation in UV-B irradiated roots; however, and in contrast to what occurs in the leaves, this response does not depend on the presence of MITOGEN ACTIVATED PROTEIN KINASE 3 (MPK3). Inhibition of primary root elongation by UV-B under our experimental conditions is also independent of the UV-B photoreceptor UV RESISTANT LOCUS 8 (UVR8) or ATAXIA TELANGIECTASIA MUTATED (ATM); but a deficiency in ATM AND RAD3-RELATED (ATR) expression increases UV-B sensitivity in the roots. Finally, our data demonstrate that UV-B affects primary root growth in various Arabidopsis accessions, showing different sensitivities to this radiation.

Proteomic Signatures of Microbial Adaptation to the Highest Ultraviolet-Irradiation on Earth: Lessons From a Soil Actinobacterium.

In the Central Andean region in South America, high-altitude ecosystems (3500–6000 masl) are distributed across Argentina, Chile, Bolivia, and Peru, in which poly-extremophilic microbes thrive under extreme environmental conditions. In particular, in the Puna region, total solar irradiation and UV incidence are the highest on Earth, thus, restraining the physiology of individual microorganisms and the composition of microbial communities. UV-resistance of microbial strains thriving in High-Altitude Andean Lakes was demonstrated and their mechanisms were partially characterized by genomic analysis, biochemical and physiological assays. Then, the existence of a network of physiological and molecular mechanisms triggered by ultraviolet light exposure was hypothesized and called “UV-resistome”. It includes some or all of the following subsystems: (i) UV sensing and effective response regulators, (ii) UV-avoidance and shielding strategies, (iii) damage tolerance and oxidative stress response, (iv) energy management and metabolic resetting, and (v) DNA damage repair. Genes involved in the described UV-resistome were recently described in the genome of Nesterenkonia sp. Act20, an actinobacterium which showed survival to high UV-B doses as well as efficient photorepairing capability. The aim of this work was to use a proteomic approach together with photoproduct measurements to help dissecting the molecular events involved in the adaptive response of a model High-Altitude Andean Lakes (HAAL) extremophilic actinobacterium, Nesterenkonia sp. Act20, under artificial UV-B radiation. Our results demonstrate that UV-B exposure induced over-abundance of a well-defined set of proteins while recovery treatments restored the proteomic profiles present before the UV-challenge. The proteins involved in this complex molecular network were categorized within the UV-resistome subsystems: damage tolerance and oxidative stress response, energy management and metabolic resetting, and DNA damage repair.

Efficient fucoidan extraction and purification from Sargassum cristaefolium and preclinical dermal biological activity assessments of the purified fucoidans

BackgroundFucoidan is a heterologous polysaccharide consisting mainly of L-fucose with sulfuric acid functional groups, and it is considered to be a repository of bioactive compounds with excellent therapeutic and medical potential, such as antioxidant, anti-inflammatory, antiangiogenic, antitumor, and antibacterial capabilities. MethodsSubcritical water extraction was used to extract fucoidan from Sargassum. Fucoidans with different molecular weight (LMW) fractions were obtained by H2O2 hydrolysis, and the effect of LMW on their bio-functions was investigated. Significant FindingsMetal chelating, iron-reducing and free radical scavenging properties of purified fucoidans demonstrated outstanding anti-oxidative capacities of SWE fractions. In cellular viability assay, SWE was not inhibitory towards RAW 264.7, HaCaT, and Hs68 cells, even when high dosages were used. Anti-inflammatory activity was brought about by SWE administration after UVB exposure, demonstrating that the injured skin tissue was repaired and collagen was regenerated, as shown by in vitro and in vivo tests.

Durability and Performance of Encapsulant Films for Bifacial Heterojunction Photovoltaic Modules.

Energy recovery from renewable sources is a very attractive, and sometimes, challenging issue. To recover solar energy, the production of photovoltaic (PV) modules becomes a prosperous industrial certainty. An important material in PV modules production and correct functioning is the encapsulant material and it must have a good performance and durability. In this work, accurate characterizations of performance and durability, in terms of photo- and thermo-oxidation resistance, of encapsulants based on PolyEthylene Vinyl Acetate (EVA) and PolyOlefin Elastomer (POE), containing appropriate additives, before (pre-) and after (post-) lamination process have been carried out. To simulate industrial lamination processing conditions, both EVApre-lam and POEpre-lam sheets have been subjected to prolonged thermal treatment upon high pressure. To carry out an accurate characterization, differential scanning calorimetry, rheological and mechanical analysis, FTIR and UV-visible spectroscopy analyses have been performed on pre- and post-laminated EVA and POE. The durability, in terms of photo- and thermo-oxidation resistance, of pre-laminated and post-laminated EVA and POE sheets has been evaluated upon UVB exposure and prolonged thermal treatment, and the progress of degradation has been monitored by spectroscopy analysis. All obtained results agree that the lamination process has a beneficial effect on 3D-structuration of both EVA and POE sheets, and after lamination, the POE shows enhanced rigidity and appropriate ductility. Finally, although both EVA and POE can be considered good candidates as encapsulants for bifacial PV modules, it seems that the POE sheets show a better resistance to oxidation than the EVA sheets.

Low-Cost Naked-Eye UVB and UVC Dosimetry Based on 3,3',5,5'-Tetramethylbenzidine.

Ultraviolet radiation (UVR) is both useful to human beings and can cause irreversible harm of varying degrees (UVA, UVB, and UVC). Especially, in areas with excessive sunlight, the appearance of UVB results in an increased risk of skin cancer. On the other hand, UV lamps (254 nm, UVC) are widely used in disinfection (air, water, and factory food) and hospital sterilization; the leakage of UVC is thus sometimes inevitable, which may cause fatal injuries to the related staff. Therefore, low-cost UV dosimetry-based personal protective equipment (PPE) and industrial monitoring devices are of great importance. Here, for the first time, we found that 3,3',5,5'-tetramethylbenzidine (TMB) could be rapidly oxidized upon UVB and UVC irradiation in a dose-dependent manner, in which TMB acts as a self-photosensitizer. Since TMB is a typical and widely used chromogenic substrate in enzyme-linked immunosorbent assay (ELISA), it is well-commercialized with low cost and vast availability worldwide, which permitted the development of low-cost naked-eye UVB and UVC dosimetry. A wearable bracelet mounted with TMB-loaded paper was developed for successful indication of whether the UVB exposure in the sunlight exceeded the minimum erythema dose (MED). In addition, we also developed a clock dial equipped with a TMB solution for unattended detection of UVC leakage from UVC disinfection lamps. The UVB- and UVC-selective coloration and low cost of TMB offered remarkable potential in facile detection of UVR in our daily life.

Title: Understanding a Low Vitamin D State in the Context of COVID-19.

While a low vitamin D state has been associated with an increased risk of infection by SARS-CoV-2 in addition to an increased severity of COVID-19 disease, a causal role is not yet established. Here, we review the evidence relating to i) vitamin D and its role in SARS-CoV-2 infection and COVID-19 disease ii) the vitamin D status in the Irish adult population iii) the use of supplemental vitamin D to treat a deficient status and iv) the application of the Bradford-Hill causation criteria. We conclude that reverse causality probably makes a minimal contribution to the presence of low vitamin D states in the setting of COVID-19. Applying the Bradford-Hill criteria, however, the collective literature supports a causal association between low vitamin D status, SARS-CoV-2 infection, and severe COVID-19 (respiratory failure, requirement for ventilation and mortality). A biologically plausible rationale exists for these findings, given vitamin D’s role in immune regulation. The thresholds which define low, deficient, and replete vitamin D states vary according to the disease studied, underscoring the complexities for determining the goals for supplementation. All are currently unknown in the setting of COVID-19. The design of vitamin D randomised controlled trials is notoriously problematic and these trials commonly fail for a number of behavioural and methodological reasons. In Ireland, as in most other countries, low vitamin D status is common in older adults, adults in institutions, and with obesity, dark skin, low UVB exposure, diabetes and low socio-economic status. Physiological vitamin D levels for optimal immune function are considerably higher than those that can be achieved from food and sunlight exposure alone in Ireland. A window exists in which a significant number of adults could benefit from vitamin D supplementation, not least because of recent data demonstrating an association between vitamin D status and COVID-19. During the COVID pandemic, we believe that supplementation with 20-25ug (800–1000 IU)/day or more may be required for adults with apparently normal immune systems to improve immunity against SARS-CoV-2. We expect that higher monitored doses of 37.5–50 ug (1,500–2,000)/day may be needed for vulnerable groups (e.g., those with obesity, darker skin, diabetes mellitus and older adults). Such doses are within the safe daily intakes cited by international advisory agencies.