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Results for “Ultraviolet B radiation”

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At least 19 recordsLinked to original sources
PubMed2026

UVB photoprotection by thiourea and (thio)semicarbazone derivatives: cellular and molecular evidence.

BACKGROUND: Ultraviolet B (UVB) radiation is a major environmental stressor that contributes to oxidative stress, inflammation, DNA damage, and ultimately an increased risk of skin carcinogenesis. The development of safer, multifaceted UV filters with improved photostability and bioprotective properties remains an important research priority. Here, alkyl chain-conjugated thiourea (I-XIX) and aryl-linked (thio)semicarbazone (XX-XXV) derivatives have been systematically assessed for their photoprotective potential against UVB-induced cellular damage. METHODS: The UV absorption properties, molar absorptivity, and photostability of the test compounds were assessed through spectroscopic studies. Cytotoxicity, effective concentrations, and bioprotective effects of the compounds were evaluated using in vitro cellular methods. RESULTS: Several compounds exhibited robust UVB absorption with high molar absorptivity, particularly semicarbazone derivatives, while displaying minimal cytotoxicity to normal human dermal fibroblasts. Among the evaluated compounds, ten compounds were found to be more photostable than benzophenone (reference compound). Selected compounds significantly reduced UVB-induced intracellular reactive oxygen species and nitric oxide production, signifying effective attenuation of oxidative and nitrosative stress. In addition, compounds IV, XXI, and XXIII alleviated UVB-induced inflammatory cascades by diminishing Interleukin-1 beta (IL-1β) and Tumor Necrosis Factor alpha (TNF-α) levels. Therefore, these compounds also protected fibroblast morphology. Moreover, the same compounds protected from DNA damage by preventing UVB-induced genomic DNA fragmentation and formation of cyclobutane pyrimidine dimers. In particular, compound XXIII displayed selective UVB absorption, better photostability, low cytotoxicity, and moderate biological photoprotection (SPF 16). CONCLUSION: Together, the results suggest that thiourea and (thio)semicarbazone derivatives, notably compound XXIII, represent promising photoprotective scaffolds requiring further formulation, in vivo, permeability, phototoxicity, and safety studies to validate their potential as UV-filtering agents.

Humans↗
PubMed2025

Prevalence and determinants of profound vitamin D deficiency (25-hydroxyvitamin D <10 nmol/L) in the UK Biobank and potential implications for disease association studies.

BACKGROUND: 25-hydroxyvitamin D (25OHD) is the principal biomarker of vitamin D status. Values below the assay detection limit (<10 nmol/L) are often reported as missing. Thus the most severely deficient participants are excluded from research which can lead to inaccurate findings such as underestimated prevalence of deficiency, overlooked risk factors, and biased evaluation of disease associations. METHODS: In total 369,626 individuals from the UK Biobank cohort were included in this study. Data on 25OHD concentration and relevant demographic and lifestyle factors such as age, supplement intake, diet, and time spent outdoors were used in the analyses. Ambient UVB radiation was approximated for each participant. 25OHD was evaluated as a categorical outcome and we reintroduced participants with 25OHD values <&#x202f;10 nmol/L (conventionally reported as missing values) back to the dataset. Adjusted regression models were used to investigate the determinants of profound (25OHD <10 nmol/L) and severe (10-25 nmol/L) vitamin D deficiency and to assess disease associations (with 25-50 nmol/L as the reference category). RESULTS: 1,784 (0.48&#x202f;%) individuals were profoundly deficient and a further 47,226 (12.78 %) individuals were severely vitamin D deficient. The proportions of profoundly and severely deficient were highest among Asians, 9&#x202f;% and 47&#x202f;%, respectively. Ambient UVB radiation was the second strongest predictor: comparing the lowest vs. highest quartile, the risk of profound deficiency was 17-fold increased and that of severe deficiency 7.5-fold increased. Use of vitamin D supplements substantially reduced risk of profound (4.4-fold) and severe (2.5-fold) deficiency, as did fish intake (5- and 1.9-fold, respectively). Profound deficiency was more strongly associated with chronic illness, diabetes, and emphysema compared to severe deficiency. CONCLUSION: The prevalence of profound and severe vitamin D deficiency among Asian and Black ethnicities in the UK is high and requires targeted action. Solar radiation is potent in protecting against profound and severe vitamin D deficiency. Studies evaluating the relationship between vitamin D status and other health outcomes may be biased if profoundly deficient participants are excluded.

Humans↗
PubMed1979

Reticular erythematous mucinosis syndrome. Report of two cases.

Two female patients had eruptions with the morphologic and histologic features of reticular erythematous mucinosis syndrome. However, both cases had features that differed from previous descriptions. In one case the eruption developed three to four weeks after a single erythemogenic sun exposure and faded after two to three weeks. The rash could be reproduced by exposure to ultraviolet B (UVB) or UVC radiation. In the other patient, the eruption involved the arms and face and spared the trunk, which is a more characteristic site of involvement; it was associated with a history of exacerbation following sun exposure, but the rash could not be reproduced on phototesting.

Adult↗
PubMed1978

Ultraviolet phototherapy and photochemotherapy of acne vulgaris.

The therapeutic value of various ultraviolet treatments was assessed in patients with moderately severe papulopustular acne. The results did not verify the common belief that ultraviolet radiation is highly beneficial. In no instance was the comedo count appreciably reduced. Modest improvement was observed with sunburn rays (UV-B) and slightly more with the combination of long ultraviolet radiation (UV-A) and UV-B. UV-A alone had the least effect. Photosensitization with coal tar and UV-A greatly aggravated acne and was notably comedogenic. Photosensitization with methoxsalen (8-methoxypsoralen) applied topically was neither harmful nor helpful.

Acne Vulgaris↗
PubMed2026

The OsUVR8-OsNAC3-OsERF117 signaling module mediates metabolic acclimation and climate adaptation in rice.

Ultraviolet-B (UV-B; 280 to 315&#xa0;nanometers) radiation increasingly threatens crop productivity, yet the genetic basis of plant adaptation remains poorly understood. We delineate a UV-B signaling module in rice that links photoreceptor activation to transcriptional reprogramming and metabolic acclimation. The AP2/ERF transcription factor OsERF117 acts as a central regulator, directly activating flavonoid and melatonin biosynthetic genes to drive photoprotective metabolite accumulation and enhance UV-B stress tolerance. Promoter variation in OsERF117 defines 10 haplotypes across 4093 rice accessions, with high-expression haplotypes enriched in high-UV-B regions and correlated with adaptive divergence. OsERF117 is transcriptionally activated by OsNAC3, with a cis-regulatory SNP at an OsNAC3-binding site modulating responsiveness and contributing to subspecies diversification. Genetic and biochemical evidence supports a model in which UV-B-activated OsUVR8 promotes OsNAC3 activity and antagonizes OsCOP1-mediated ubiquitination and degradation in rice. This OsUVR8-OsCOP1-OsNAC3-OsERF117 module reveals how UV-B perception drives regulatory and metabolic diversification, offering targets for breeding UV-B-resilient crops.

Oryza↗
PubMed1977

Tissue changes resulting from the injection of gamma-irradiated cells into the gynogenetic teleost, Poecilia formosa.

In previous studies a clone of the gynogenetic fish, Poecilia formosa (the Amazon molly), was successfully used as a test animal to identify ultraviolet-induced damage. This work has been extended, and the fish system was used to detect damage caused byionizing radiation. Fish cells, exposed in vitro to 250 and 500 rads, were injected into young isogenic recipients, and 9 months later the fish were examined grossly and histologically. Two of the most conspicuous changes that resulted were the development of extensive invasive thyroid hyperplasia and hypertrophy body, with an apparent reduction in the amount of hemato-poietic tissue in the head kidney and spleen. We discuss the difference between the responses of the recipient fish to cells exposed to ionizing radiation and to cells exposed to ultraviolet light.

Animals↗