Low UV Doses Research Articles

Development of an Anthracene-Coated SMF-MMF-SMF Sensor for Low-Dose UV Radiation Detection and Dosimetry

Development of an Anthracene-Coated SMF-MMF-SMF Sensor for Low-Dose UV Radiation Detection and Dosimetry

Revealing the UV response of melanocytes in xeroderma pigmentosum group A using patient-derived induced pluripotent stem cells

BackgroundXeroderma pigmentosum (XP) is characterized by photosensitivity that causes pigmentary disorder and predisposition to skin cancers on sunlight-exposed areas due to DNA repair deficiency. Patients with XP group A (XP-A) develop freckle-like pigmented maculae and depigmented maculae within a year unless strict sun-protection is enforced. Although it is crucial to study pigment cells (melanocytes: MCs) as disease target cells, establishing MCs in primary cultures is challenging. ObjectiveElucidation of the disease pathogenesis by comparison between MCs differentiated from XP-A induced pluripotent stem cells (iPSCs) and healthy control iPSCs on the response to UV irradiation. MethodsiPSCs were established from a XP-A fibroblasts and differentiated into MCs. Differences in gene expression profiles between XP-A-iPSC-derived melanocytes (XP-A-iMCs) and Healthy control iPSC-derived MCs (HC-iMCs) were analyzed 4 and 12 h after irradiation with 30 or 150 J/m2 of UV-B using microarray analysis. ResultsXP-A-iMCs expressed SOX10, MITF, and TYR, and showed melanin synthesis. Further, XP-A-iMCs showed reduced DNA repair ability. Gene expression profile between XP-A-iMCs and HC-iMCs revealed that, numerous gene probes that were specifically upregulated or downregulated in XP-A-iMCs after 150-J/m2 of UV-B irradiation did not return to basal levels. Of note that apoptotic pathways were highly upregulated at 150 J/m2 UV exposure in XP-A-iMCs, and cytokine-related pathways were upregulated even at 30 J/m2 UV exposure. ConclusionWe revealed for the first time that cytokine-related pathways were upregulated even at low-dose UV exposure in XP-A-iMCs. Disease-specific iPSCs are useful to elucidate the disease pathogenesis and develop treatment strategies of XP.

Acute exposure to ultraviolet radiation targets proteins involved in collagen fibrillogenesis.

Introduction: Exposure to chronic, low-dose UV irradiation (UVR) can lead to premature ageing of the skin. Understanding which proteins are affected by acute UVR and photo-dynamically produced reactive oxygen species (ROS) could help to inform strategies to delay photoageing. Conventional biochemical analyses can be used to characterize UVR/ROS-induced damage on a protein-by-protein basis and we have previously shown using SDS-PAGE that collagen I and plasma fibronectin are respectively resistant and susceptible to physiological doses of UVR. The aim of this study was to screen a complex proteome for UVR-affected proteins. Methods: This study employed a sensitive mass spectrometry technique (peptide location fingerprinting: PLF) which can identify structure associated differences following trypsin digestion to characterize the impact of UVR exposure on purified collagen I and tissue fibronectin and to identify UVR-susceptible proteins in an ECM-enriched proteome. Results: Using LC/MS-MS and PLF we show that purified mature type-I collagen is resistant to UVR, whereas purified tissue fibronectin is susceptible. UV irradiation of a human dermal fibroblast-deposited ECM-enriched proteome in vitro, followed by LC/MS-MS and PLF analysis revealed two protein cluster groups of UV susceptible proteins involved in i) matrix collagen fibril assembly and ii) protein translation and motor activity. Furthermore, PLF highlighted UV susceptible domains within targeted matrix proteins, suggesting that UV damage of matrix proteins is localized. Discussion: Here we show that PLF can be used to identify protein targets of UVR and that collagen accessory proteins may be key targets in UVR exposed tissues.

Radiation Curing of Phosphorus Telomer-Based Coatings Using UV LEDs or Medium-Pressure Mercury Lamp

In the presented study, UV LEDs (365 nm) or a medium-pressure mercury lamp (UV-ABC) were verified as UV radiation sources initiating the photocrosslinking process of varnishes based on novel photopolymerizable phosphorus (meth)acrylate oligomers. Coating formulations were composed of (meth)acrylic/styrene telomers with terminal P-atoms (prepared via a UV phototelomerization process) and different photoinitiators (HAPs, APOs, or APO blends). The kinetics of the UV crosslinking process of the coating formulations depending on UV irradiation and the UV range was investigated by the photo-DSC method. Moreover, the hardness of the varnishes and the conversion of double bonds using the FTIR method were tested. The photopolymerization rate and the photoinitiation index, depending on the type of photoinitiator, were as follows: APOs < APO blends < HAPs. However, the highest coating hardness results were obtained using the least reactive photoinitiator from the APO group, i.e., Omnirad TPOL, or a mixture of three different types of acylphosphine (Omnirad BL 750). The greater effectiveness of the above-mentioned APOs over HAP was also demonstrated when using a UV LED lamp at 365 nm with a low UV dose and UV irradiance, thanks to the presence of phosphoric acid diester in the coating composition, acting as both a telogen and an antioxidant.

Fine-tuned photochromic WO3-x thin films: A detailed study from structural analysis to UV photo-sensing application

The oxygen substoichiometry of as-prepared WO3 (tungsten trioxide) nano-powders (NPs) from a polyol process was tuned via peptization of the NPs in aqueous solutions of different Cr2O72− oxidizing concentrations. The as-synthesized materials have been characterized by X-ray scattering (XRD and PDF), transmission electron microscopy (TEM), X-ray photoelectron (XPS), and UV-VIS photochromic activity. The local atomic structure of WO3-X was investigated using total scattering atomic pair distribution function (PDF) analysis based on X-ray total scattering data collected on powder at ambient conditions. The PDF analysis confirms that the crystal structure of all studied samples can be described in terms of very small crystallites with a P21/n space-group monoclinic framework but with anomalous unit cell distortion parameters, indicating that small crystallite sizes resulted in a larger monoclinic distortion (as measured by the beta angle of the unit cell). The nanometer dimension of the crystallites combined as well as the oxygen-tungsten stoichiometric ratio control, are key features for optimized photochromic properties. Moreover, we present the fabrication of a WO3-x thin film based UV photosensor, which was carried out on silica glass substrates via the dip-coating method. The obtained films exhibited a UV photoresponse and photoelectric characteristics at 5 V bias voltages able to detect very low UV doses, inferior to 10 W/m2. The photo-detection measurements prove the usability of our device as a UV photodetector with a good responsivity of 0.37 A/W and external quantum efficiency of more than 100% even at a very low power density (9.2 W/m2) of UV illumination.

Live cell transcription-coupled nucleotide excision repair dynamics revisited

Transcription–blocking lesions are specifically targeted by transcription-coupled nucleotide excision repair (TC-NER), which prevents DNA damage-induced cellular toxicity and maintains proper transcriptional processes. TC-NER is initiated by the stalling of RNA polymerase II (RNAPII), which triggers the assembly of TC-NER-specific proteins, namely CSB, CSA and UVSSA, which collectively control and drive TC-NER progression. Previous research has revealed molecular functions for these proteins, however, exact mechanisms governing the initiation and regulation of TC-NER, particularly at low UV doses have remained elusive, partly due to technical constraints. In this study, we employ knock-in cell lines designed to target the endogenous CSB gene locus with mClover, a GFP variant. Through live cell imaging, we uncover the intricate molecular dynamics of CSB in response to physiologically relevant UV doses. We showed that the DNA damage-induced association of CSB with chromatin is tightly regulated by the CSA-containing ubiquitin-ligase CRL complex (CRL4CSA). Combining the CSB-mClover knock-in cell line with SILAC-based GFP-mediated complex isolation and mass-spectrometry-based proteomics, revealed novel putative CSB interactors as well as discernible variations in complex composition during distinct stages of TC-NER progression. Our work not only provides molecular insight into TC-NER, but also illustrates the versatility of endogenously tagging fluorescent and affinity tags.

Investigation of photoluminescence, thermoluminescence, and energy transfer mechanism in Ce/Dy co-doped Sr2Al2SiO7

In the present manuscript, we report the luminescence properties and energy transfer mechanism of Ce/Dy co-doped Sr2Al2SiO7 (SASO) phosphors prepared through the solid-state reaction method. Phase identification was done through a powder X-Ray diffraction tool and the obtained diffractogram confirms the formation of the desired phase. The Photoluminescence excitation and emission spectra of the prepared samples were investigated. Photoluminescence studies revealed that the luminescence intensity rises with increasing Dy concentration and optimized intensity was observed at 1 mol%. The energy transfer in the host has been attained successfully to produce color tunability. The Commission International de I'Eclairage (CIE) chromaticity coordinates and correlated color temperature (CCT) has been calculated. The energy transfer mechanism is further investigated via Thermoluminescence (TL) spectra. Further, the TL properties of synthesized phosphors were analyzed via the glow curve method along with varying UV doses. As compared to the single-doped phosphors, the TL glow curve indicates that very high intensity is observed at very low UV doses and the major TL peak is located in a higher temperature region. The calculated kinetic parameter indicates that Ce/Dy co-doped SASO has both shallow and deeper traps. All these findings suggest the potential applicability of synthesized phosphors as a low UV dosimeter.

Performance of the SolWat system operating in static mode vs. dynamic for wastewater treatment: Power generation and obtaining reclaimed water

Two hybrid SolWat systems operating in static (without flow circulation) versus dynamic (with flow circulation) mode were simultaneously compared. This work aims to demonstrate the viability of SolWat in dynamic mode to: a) adapt to the operation of the WWTP with a continuous flow, in which the wastewater flows continuously for treatment, b) treat a larger volume of water in the system and c) increase the cooling of the PV modules thanks to the cooling of the temperature of the water sample to improve the energy efficiency in the system. Real secondary wastewater effluents from wastewater treatment plants were used, using solar energy for water disinfection and photovoltaic energy production, in order to use the SolWat systems and implement it as a tertiary treatment. A total of five experiments were performed during autumn, winter, spring and summer. Solar disinfection of Escherichia coli, Enterococcus faecalis and Clostridium perfringens was assessed, and physicochemical parameters were also analysed. The UV dose received by the SolWat systems was the same, but not for the microorganisms in the water sample. The static SolWat irradiated a particle (microorganism) for 4 h, while the dynamic SolWat irradiated intermittently, so the latter system received a shorter UV exposure time, and therefore a lower UV dose. Results indicated that, although the microorganisms did not obtain the absolute bacterial inactivation during the SODIS treatment in any SolWat system, adequate inactivation levels were achieved to allow the reuse of the water for various uses (Royal Decree 1620/2007, Regulation (EU) 2020/741), although to a lesser extent for SolWat in dynamic mode, which treated twice the volume of water and reached cooler temperatures. C. perfringens proved to be the most resistant bacterium tested. The total photovoltaic energy production in the dynamic mode system was more energy efficient than the static mode, being even more efficient than the single PV reference system during the spring (3.5%) and summer (2.7%) test, due to the compensating effect by the cooling of the water on the photovoltaic module against the losses caused by radiation.

Formation Mechanism of Microbial Diversity in Artificial Intelligence Devices due to Intermediate Disturbance by Low-Dose UV Radiation for Complementary Medicine.

The development of artificial intelligence devices in the complementary medicine field is rapid and the surface microbial diversity pollution was found with periodic low-dose ultraviolet radiation (LDUVR). Since artificial intelligence devices do not have enough different types of substrates for microbial communities, it is unclear how the great microbial diversity can emerge and persist, as this clearly defies the competitive exclusion principle of ecology. In this study, the 5 most common genera in the artificial intelligence devices, Escherichia, Pseudomonas, Streptococcus, Staphylococcus and Aeromonas have been sampled without and with periodic LDUVR, respectively. A new hypothesis was put up to clarify the construction and maintenance process of high microbiological diversity in artificial intelligence devices by comparing and evaluating the variations between the dynamic response characteristics of their relative abundances in the two scenarios as follows: the periodic LDUVR can be regarded as an adverse factor with intermediate disturbance, causing stronger microbial stochastic growth responses (SGR) which would inevitably give rise to stronger random variation of the other important processes tightly correlated with SGR, such as intra- and interspecific competition process, and substrates production and consumption process, which could effectively diminish the auto- and cross-correlation of stochastic processes of microbial populations, alleviating the intra- and inter-specific competitions. In artificial intelligence devices with LDUVR, these crucial succession processes can propel the microbial communities to generate and sustain a high species diversity. Finally, thorough Monte Carlo simulations were used to thoroughly confirm the idea. This research can build the theoretical groundwork, offer fresh viewpoints, and suggest potential microbial prevention strategies for the succession of microbial communities in LDUVR.

Diploid-associated adaptation to chronic low-dose UV irradiation requires homologous recombination in Saccharomyces cerevisiae.

Ultraviolet-induced DNA lesions impede DNA replication and transcription and are therefore a potential source of genome instability. Here, we performed serial transfer experiments on nucleotide excision repair-deficient (rad14Δ) yeast cells in the presence of chronic low-dose ultraviolet irradiation, focusing on the mechanisms underlying adaptive responses to chronic low-dose ultraviolet irradiation. Our results show that the entire haploid rad14Δ population rapidly becomes diploid during chronic low-dose ultraviolet exposure, and the evolved diploid rad14Δ cells were more chronic low-dose ultraviolet-resistant than haploid cells. Strikingly, single-stranded DNA, but not pyrimidine dimer, accumulation is associated with diploid-dependent fitness in response to chronic low-dose ultraviolet stress, suggesting that efficient repair of single-stranded DNA tracts is beneficial for chronic low-dose ultraviolet tolerance. Consistent with this hypothesis, homologous recombination is essential for the rapid evolutionary adaptation of diploidy, and rad14Δ cells lacking Rad51 recombinase, a key player in homologous recombination, exhibited abnormal cell morphology characterized by multiple RPA-yellow fluorescent protein foci after chronic low-dose ultraviolet exposure. Furthermore, interhomolog recombination is increased in chronic low-dose ultraviolet-exposed rad14Δ diploids, which causes frequent loss of heterozygosity. Thus, our results highlight the importance of homologous recombination in the survival and genomic stability of cells with unrepaired lesions.

Carcinogenic effects of prolonged daily low-emission phototherapy in psoriasis.

BackgroundLow‐dose UV treatment has been shown to be effective in mild psoriasis. However, the prolonged use of this treatment modality may raise concerns about its safety. These concerns are mainly focused on potential carcinogenic risks and overuse of this treatment modality.ObjectivesThis study was set out to evaluate possible carcinogenic risks of prolonged low‐dose phototherapy.MethodsThree groups of psoriasis patients were evaluated: patients with local treatment only (n = 15); low‐dose UV treatment at home for at least 18 months (n = 39); and patients with conventional NB‐UVB (n = 8). Patients underwent visual inspection for signs of photoageing, and p53, CPDs and γH2AX were measured in skin biopsies. Patients undergoing low‐dose phototherapy answered a survey about their recent patterns of use in a survey.ResultsIn the skin biopsies, low‐dose UV treatment caused a lower amount of CPDs (p = .016) and p53 (p = .015) than NB‐UVB. γH2AX did not show a significant difference. Self‐report in patients undergoing low‐dose phototherapy showed only one case of overuse (2.7%). Visual skin inspection showed no difference in signs of photoageing in the three groups.ConclusionProlonged treatment with low‐dose UV for 18 months appears at least as safe as a course of conventional NB‐UVB.

308-nm excimer laser in the treatment of a localized recalcitrant form of perioral dermatitis: Case report

In the last two decades, 308-nm excimer laser has been increasingly recognized as a therapeutic alternative for several dermatological conditions, being currently FDA approved for the treatment of localized vitiligo and moderately severe localized psoriasis unresponsive to topical treatments. We describe the case of a 17-year-old with a recalcitrant form of dermatitis occupying the entire perioral region, previously unresponsive to several treatments, who was treated with 308-nm excimer laser with an excellent result. 308-nm monochromatic excimer laser has several advantages over other types of phototherapy, including lower UV dose exposure, shorter courses of therapy and a better sparing of adjacent tissue. Although infrequently used, 308-nm excimer laser certainly has a vast potential in Dermatology, particularly regarding recalcitrant and localized inflammatory conditions, such as the one we present.

Bioactive substances in the stratum corneum of the epidermis found as indicators of skin damage due to sun exposure.

Background/PurposeAlthough an inflammatory response upon acute injury caused by ultraviolet radiation (UV) can be observed immediately, the influence of long‐term, repetitive low‐dose UV exposure on the skin cannot be precisely perceived, making early detection of chronic damage difficult. This study investigated bioactive substances in the stratum corneum as a potential early and sensitive indicator of the influence of sun exposure on the skin using receiver operating characteristic (ROC) analysis.MethodsReceiver operating characteristic analysis was performed to assess the responsiveness of cytokines [interleukin (IL)‐1α, IL‐1 receptor antagonist (IL‐1ra), IL‐10, tumor necrosis factor (TNF)‐α], BCL2‐associated protein X (Bax), Toll‐like receptor (TLR)3, and TLR4 in the stratum corneum of healthy people exposed (dorsum of the hand) and unexposed (inner arm) to UV. Sunscreen was applied to patients with photodermatosis for 4 weeks to evaluate changes in IL‐1ra/IL‐1α, TNF‐α, Bax, and TLR3 levels after sunscreen application, as these molecules exhibited high responsiveness to sun exposure according to ROC analysis. In addition, IL‐1ra, IL‐1α, and IL‐10 levels were quantified by enzyme‐linked immunosorbent assay, and TNF‐α, Bax, TLR3, and TLR4 levels were semi‐quantitatively assessed by immunocytochemistry.ResultsReceiver operating characteristic analysis identified IL‐1ra/IL‐1α, TNF‐α, Bax, and TLR3 in the stratum corneum as highly responsive to sun exposure. Moreover, in participants, including patients with photodermatosis, IL‐1ra/IL‐1α, TNF‐α, and Bax levels decreased significantly after sunscreen application.ConclusionThe results revealed that IL‐1ra/IL‐1α, TNF‐α, and Bax in the stratum corneum represent sensitive indicators of the influence of sun exposure on the skin.

FANCI functions as a repair/apoptosis switch in response to DNA crosslinks.

Cells counter DNA damage through repair or apoptosis, yet a direct mechanism for this choice has remained elusive. When facing interstrand crosslinks (ICLs), the ICL-repair protein FANCI heterodimerizes with FANCD2 to initiate ICL excision. We found that FANCI alternatively interacts with a pro-apoptotic factor, PIDD1, to enable PIDDosome (PIDD1-RAIDD-caspase-2) formation and apoptotic death. FANCI switches from FANCD2/repair to PIDD1/apoptosis signaling in the event of ICL-repair failure. Specifically, removing key endonucleases downstream of FANCI/FANCD2, increasing ICL levels, or allowing damaged cells into mitosis (when repair is suppressed) all suffice for switching. Reciprocally, apoptosis-committed FANCI reverts from PIDD1 to FANCD2 after a failed attempt to assemble the PIDDosome. Monoubiquitination and deubiquitination at FANCI K523 impact interactor selection. These data unveil a repair-or-apoptosis switch in eukaryotes. Beyond ensuring the removal of unrepaired genomes, the switch's bidirectionality reveals that damaged cells can offset apoptotic defects via de novo attempts at lesion repair.

Release of nitrogenous disinfection by-product precursors in algae-laden water under UV radiation

Abstract Nitrogen-containing organic compounds and nitrogenous disinfection by-products (N-DBPs) in drinking water have attracted attention in the field of water treatment. Metabolites released during algae growth contain a variety of organic nitrogen species, which are called N-DBP precursors. The aim of this paper is to elucidate how N-DBP precursors are released under UV radiation, as well as investigate the variations of their chemical properties. The results show that through UV radiation, the physiological metabolism of algal cells was disordered and the properties of their metabolites were changed. The dissolved organic nitrogen (DON) compound concentration increased rapidly from 5.38 at the beginning to 11.11 mg/L after 30 min of radiation, and then increased steadily from 11.11 to 23.71 mg/L during a further 210 min of radiation. Derivation results of the curves for algae and DON concentration variations shows that when 1 × 1010 algal cells were destroyed, 8.31 mg DON was released into the solution during the first 30 min of radiation. Low dose UV radiation brought a slight decline of the specific N-DBP formation potential due to changes in the extracellular organic matter (EOM) structure without destroying the algal cells, which was conducive to controlling the formation potential of N-DBPs. Long-time UV radiation can bring a significant increase in N-DBP formation potential. After 4 hours of ultraviolet radiation, the total formation potential of N-DBPs in the solution increased from about 84.9 μg/L to about 213.5 μg/L, 2.5 times higher than the initial solution. The N-DBP formation potential increases obviously during the first 10–30 min UV radiation, and then decreases slightly in the subsequent 30–240 min radiation.

Membrane fouling control by UV/persulfate in tertiary wastewater treatment with ultrafiltration: A comparison with UV/hydroperoxide and role of free radicals

The membrane fouling caused by effluent organic matter (EfOM) is a bottleneck for application of ultrafiltration (UF) in tertiary wastewater treatment. In this study, two ultraviolet-based oxidation pretreatments, i.e., ultraviolet/persulfate (UV/PS) and ultraviolet/hydrogen peroxide (UV/H2O2), were used to alleviate EfOM fouling at a low UV dose of 2.36 × 103 mJ cm−2, in consideration of the widely use of UV radiation for disinfection in wastewater treatment plants. Effects of the pretreatments on characteristics of EfOM were investigated in terms of fluorescence spectrum, molecular weight distribution, and hydrophobicity. Moreover, filtration tests were performed to assess impacts of the oxidation pretreatments on flux decline, fouling reversibility, and fouling mechanisms. The results showed that the UV/PS pretreatment substantially reduced flux decline and improved fouling reversibility during filtration of the secondary effluent, attributed to efficient degradation (~67%, in terms of UV254) and partial mineralization (~39%, in terms of DOC) of EfOM. In particular, the irreversible resistance was decreased by nearly one order of magnitude at the PS dose of 1.0 mM. UV/H2O2 was not effective in EfOM fouling control under the conditions investigated. The UV/PS pretreatment resulted in a shift of mechanisms for EfOM fouling from successive pore blocking and cake filtration to single standard blocking, attributing to preferential degradation of macromolecular components in EfOM and a weakened role of cake interception. The radical quenching experiment showed that the sulfate radicals played a dominant role in EfOM fouling control by UV/PS, and that transformation of sulfate radicals into hydroxyl radicals negatively affected EfOM fouling control.

Boosting up printability of biomacromolecule based bio-ink by modulation of hydrogen bonding pairs

This study describes low dose UV curable and bioprintable new bioink made of hydrogen bond donor-acceptor adaptor molecule 2-isocyanatoethyl methacrylate (NCO)modified gelatin (NCO-Gel). Our theoretical calculations demonstrate that insertion of 2-isocyanatoethyl methacrylate doubles the interaction energy (500 meV) between gelatin chains providing significant contribution in interchain condensation and self-organization as compared to methacrylic anhydride modified gelatin (GelMA). The NCO-Gel exhibits peak around 1720 cm−1 referring to bidentate hydrogen bonding between H-NCO and its counterpart OCNH. These strong interchain interactions drive chains to be packed and thereby facilitating UV crosslinking. The NCO-Gel is exhibiting a rapid, 10 s gelation process by the exposure of laser (3 W, 365 nm). The dynamic light scattering characterization also reveals that NCO-Gel has faster sol to gel transition as compared to GelMA depending on the UV curing time. The NCO-Gel was found to be more firm and mechanically strong that provides advantages in molding as well as bioprinting processes. Bioprinted NCO-Gel has shown sharp borders and stable 3D geometry as compared to GelMA ink under 10 s UV curing time. The cell viability tests confirm that NCO-Gel facilitates cell proliferation and supports cell viability. We foresee that NCO-Gel bioink formulation provides a promising opportunity when low dose UV curing and rapid printing are required.

PH-responsive UV crosslinkable chitosan hydrogel via “thiol-ene” click chemistry for active modulating opposite drug release behaviors

Numbers of UV crosslinkable chitosan hydrogels through chemical modification had drawn increasing attention, however most of these chitosan hydrogels lost the pH-responsive performance because plenty of amino groups (‒NH2) in chitosan were consumed by reacting with other functional groups. To construct a pH-responsive UV-crosslinkable chitosan hydrogel for active modulating drug release with desired behavior, C6-OH selectively modified chitosan via protection/deprotection strategy to amino groups was synthesized, the allyl groups on C6 site and amino groups on C2 site endowed chitosan with UV crosslinking capability and pH responsiveness, respectively. Rapid UV crosslinking gelation (30 s) with low-dose UV irradiation (4 mW/cm2) via “thiol-ene” click chemistry were demonstrated for the patterned microgel and in-situ formed hydrogel in vivo. The swelling and shrinkage of hydrogel could active modulate the opposite release behaviors of doxorubicin (DOX) and bovine serum albumin (BSA) in different pH medium. The smart UV-crosslinkable chitosan hydrogel via click chemistry might provide a new drug carrier for active modulating opposite drug release behaviors.

Noninvasive Assessment of Epidermal Genomic Markers of UV Exposure in Skin

The measurement of UV-induced DNA damage as a dosimeter of exposure and predictor of skin cancer risk has been proposed by multiple groups. Although UV-induced mutations and adducts are present in normal-appearing UV-exposed epidermis, sampling normal nonlesional skin requires noninvasive methods to extract epidermal DNA for analysis. Here, we demonstrate the feasibility of such an approach, termed surfactant-based tissue acquisition for molecular profiling. Sampling in patients was performed using a felt-tip pen soaked in a mixture of surfactants (Brij-30/N-decyl-N,N-dimethyl-3-ammonio-1-propanesulfonate). In mice, we show that the epidermis can be selectively removed without scarring, with complete healing within 2 weeks. We exposed hairless mice to low-dose UV radiation over a period of 3 months and serially sampled them through up to 2 months following the cessation of UV exposure, observing a progressive increase in a UV signature mutational burden. To test whether surfactant-based tissue acquisition for molecular profiling could be applied to human patients, samples were collected from sun-exposed and sun-protected areas, which were then subjected to high-depth targeted exome sequencing. Extensive UV-driven mosaicism and substantially increased mutational loads in sun-exposed versus sun-protected areas were observed, suggesting that genomic measures, as an integrated readout of DNA damage, repair, and clonal expansion, may be informative markers of UV exposure.

Low-dose UV radiation before running wheel access activates brown adipose tissue

In previous preclinical studies, low (non-burning) doses of UV radiation (UVR) limited weight gain and metabolic dysfunction in mice fed with a high-fat diet. Here, we explored the effects of low-dose UVR on physical activity and food intake and mechanistic pathways in interscapular brown adipose tissue (iBAT). Young adult C57Bl/6J male mice, housed as individuals, were fed a high-fat diet and exposed to low-dose UVR (sub-oedemal, 1 kJ/m2 UVB, twice-a-week) or 'mock' treatment, with or without running wheel access (2 h, for 'moderate' physical activity) immediately after phototherapy. There was no difference in distance run in mice exposed to UVR or mock-treated over 12 weeks of exposure to running wheels (P = 0.14). UVR (alone) did not significantly affect food intake, adiposity, or signs of glucose dysfunction. Access to running wheels increased food intake (after 10 weeks, P ≤ 0.02) and reduced gonadal white adipose tissue and iBAT mass (P ≤ 0.03). Body weight and hepatic steatosis were lowest in mice exposed to UVR with running wheel access. In the iBAT of mice exposed to UVR and running wheels, elevated Atgl, Cd36, Fasn, Igf1, Pparγ, and Ucp1 mRNAs and reduced CD11c on F4-80 + MHC class II+ macrophages were observed, while renal Sglt2 mRNA levels were increased, compared to high-fat diet alone (P ≤ 0.03). Blood levels of 25-hydroxyvitamin D were not increased by exposure to UVR and/or access to running wheels. In conclusion, when combined with physical activity, low-dose UVR may more effectively limit adiposity (specifically, body weight and hepatic steatosis) and modulate metabolic and immune pathways in iBAT.