Quantifying the Photosynthetic Quantum Yield of Ultraviolet-A1 Radiation.

Although it powers photosynthesis, ultraviolet-A1 radiation (UV-A1) is usually not defined as photosynthetically active radiation (PAR). However, the quantum yield (QY) with which UV-A1 drives net photosynthesis rate (A) is unknown, as are the kinetics of A and chlorophyll fluorescence under constant UV-A1 exposure. We measured A in leaves of six genotypes at four spectra peaking at 365, 385, 410 and 450 nm, at intensities spanning 0-300 µmol m s-1. All treatments powered near-linear increases in A in a wavelength-dependent manner. QY at 365 and 385 nm was linked to the apparent concentration of flavonoids, implicating the pigment in reductions of photosynthetic efficiency under UV-A1; in several genotypes, A under 365 and 385 nm was negative regardless of illumination intensity, suggesting very small contributions of UV-A1 radiation to CO2 fixation. Exposure to treatment spectra for 30 min caused slow increases in nonphotochemical quenching, transient reductions in A and dark-adapted maximum quantum yield of photosystem II, that depended on wavelength and intensity, but were generally stronger the lower the peak wavelength was. We conclude that UV-A1 generally powers A, but its definition as PAR requires additional evidence of its capacity to significantly increase whole-canopy carbon uptake in nature.

Photoprotective sulfated mannogalactan from heterotrophic Bacillus velezensis blocks UV-A mediated matrix metalloproteinase expression and nuclear DNA damage in human dermal fibroblast.

Prolonged exposure of human dermal fibroblasts (HDF) to ultraviolet (UV) radiation triggers the production of reactive oxygen species by upregulating the expression of matrix metalloproteinases (MMPs), causing type-I collagen degradation and photoaging. A sulfated (1 â†’ 3)/(1 â†’ 4) mannogalactan exopolysaccharide (BVP-2) characterized as [→3)-α-Galp-{(1 â†’ 4)-α-6-O-SO3-Manp}-(1 â†’ 3)-α-6-O-SO3-Galp-(1→] was isolated from seaweed-associated heterotrophic bacterium Bacillus velezensis MTCC13097. Whole genome analysis of B. velezensis MTCC13097 (Accession number JAKYLL000000000) revealed saccharine biosynthetic gene clusters for exopolysaccharide production. BVP-2 administered cells showed noteworthy reduction in mitochondrial superoxide (∼85 %, p < 0.05) and ROS production (62 %) than those exhibited by UV-A irradiated HDF cells. Oxidative imbalance in HDF cells (after UV-A exposure) was recovered with BVP-2 treatment by significantly downregulating nitric oxide (NO) production (98.6 µM/mL, 1.9-fold) and DNA damage (⁓67 %) in comparison with UV-A induced cells (191.8 µM/mL and 98.7 %, respectively). UV-irradiated HDF cells showed a ∼30-50 % downregulation in the expression of MMPs (1, 2, and 9) following treatment with BVP-2. Considerable amount of sulfation (18 %) along with (1 â†’ 3)/(1 â†’ 4) glycosidic linkages in BVP-2 could be pivotal factors for down-regulation of the intracellular MMP-1, which was further supported by molecular docking and structure-activity studies. The (1 â†’ 3)/(1 â†’ 4)-linked bacterial exopolysaccharide (BVP-2) might be used as prospective natural lead to attenuate and mitigate UV-A-induced photoaging.

Bacteria and RNA virus inactivation with a high-irradiance UV-A source.

Disinfection with LED lamps is a promising ecological and economical substitute for mercury lamps. However, the optimal time/dose relationship needs to be established. Pathogen inactivation by UV-A primarily relies on induced reactive oxygen species (ROS) formation and subsequent oxidative damage. While effective against bacteria and enveloped viruses, non-enveloped viruses are less sensitive. In this study, we explored the disinfection properties of 10 W UV-A LED, emitting in the 365-375 nm range. UV-A at high values of irradiance (~ 0.46 W/cm2) can potentially induce ROS formation and direct photochemical damage of the pathogen nucleic acids, thus improving the disinfection. The UV-A inactivation was evaluated for the bacterium Escherichia coli (E. coli), non-enveloped RNA bacteriophage MS2, and enveloped mammalian RNA virus-Semliki Forest virus (SFV). The 4 log10 reduction doses for E. coli and SFV were 268 and 241 J/cm2, respectively. Furthermore, in irradiated E. coli, ROS production positively correlated with the inactivation rate. In the case of MS2 bacteriophage, the 2.5 log10 inactivation was achieved by 679 J/cm2 within 30 min of irradiation. The results demonstrate significant disinfection efficiency of non-enveloped virus MS2 using high-irradiance UV-A. This suggests a potential strategy for improving the inactivation of UV-A-unsusceptible pathogens, particularly non-enveloped viruses. Additionally, the direct UV-A irradiation of self-replicating viral RNA from SFV led to a significant loss of viral gene expression in cells transfected with the irradiated RNA. Therefore, the virus inactivation mechanism of high-irradiance UV-A LED can be partially determined by the direct damage of viral RNA.

UV light and the ocular lens: a review of exposure models and resulting biomolecular changes.

UV light is known to cause damage to biomolecules in living tissue. Tissues of the eye that play highly specialised roles in forming our sense of sight are uniquely exposed to light of all wavelengths. While these tissues have evolved protective mechanisms to resist damage from UV wavelengths, prolonged exposure is thought to lead to pathological changes. In the lens, UV light exposure is a risk factor for the development of cataract, which is a condition that is characterised by opacity that impairs its function as a focusing element in the eye. Cataract can affect spatially distinct regions of the lens. Age-related nuclear cataract is the most prevalent form of cataract and is strongly associated with oxidative stress and a decrease in the antioxidant capacity of the central lens region. Since UV light can generate reactive oxygen species to induce oxidative stress, its effects on lens structure, transparency, and biochemistry have been extensively investigated in animal models in order to better understand human cataract aetiology. A review of the different light exposure models and the advances in mechanistic understanding gained from these models is presented.

UV-A Flexible LEDs Based on Core-Shell GaN/AlGaN Quantum Well Microwires.

Nanostructured ultraviolet (UV) light sources represent a growing research field in view of their potential applications in wearable optoelectronics or medical treatment devices. In this work, we report the demonstration of the first flexible UV-A light emitting diode (LED) based on AlGaN/GaN core-shell microwires. The device is based on a composite microwire/poly(dimethylsiloxane) (PDMS) membrane with flexible transparent electrodes. The electrode transparency in the UV range is optimized: namely, we demonstrate that single-walled carbon nanotube electrodes provide a stable electrical contact to the membrane with high transparency (70% at 350 nm). The flexible UV-A membrane demonstrating electroluminescence around 345 nm is further applied to excite Zn-Ir-BipyPDMS luminophores: the UV-A LED is combined with the elastic luminophore-containing membrane to produce a visible amber emission from 520 to 650 nm. The obtained results pave the way for flexible inorganic light-emitting diodes to be employed in sensing, detection of fluorescent labels, or light therapy.

Impact of low-dose UV-A in Caenorhabditis elegans during candidate bacterial infections.

Ultraviolet radiation is a non-ionizing radiation produced by longer wavelength energy sources with lower frequency and is categorized into UV-A, UV-B, and UV-C. Minimal exposure to this radiation has several health benefits, which include treating microbial contaminations and skin therapies. However, the antimicrobial action of low-dose UV-A during pathogenic bacterial infections is still unrevealed. In this study, the impact of low-dose UV-A as pre- or post-treatment using the model organism, Caenorhabditis elegans with candidate pathogens (Acinetobacter baumannii and Staphylococcus aureus) mediated infections was investigated. The results indicated enrichment of metabolites, reduced level of antioxidants, increased expression of dopamine biosynthesis and transportation, and decrease in serotonin biosynthesis when the organism was exposed to low-dose UV-A for 5 min. This, in turn, elevated the expression of candidate regulatory proteins involved in lifespan determination, innate immunity, and cAMP-response element binding protein (CREB), which appear to increase the lifespan and brood size of C. elegans during A. baumannii and S. aureus infections. The findings suggested that the low-dose UV-A treatment during A. baumannii and S. aureus infections prolonged the lifespan and increased the egg-laying capacity of C. elegans.

Antibacterial efficacy interference of the photocatalytic TiO2 nanoparticle and the lytic bacteriophage vb_EcoS_bov25_1D on the Enterohaemorragic Escherichia coli strain Sakai.

Post-antibiotic era requires the use of alternative pesticides against bacterial infections. One potential application field is agriculture, where pesticides are routinely applied in combinations. In this study we tested the interference of antibacterial effects of two alternative antimicrobials with basically different mode of actions if applied together in vitro by using the Enterohemorrhagic E. coli strain Sakai as a modelorganism, one strain of a pathotype that is frequently associated with meat and plant derived infections. TiO2 is a photocatalytically active nanomaterial, which can generate reactive oxygen species (ROS), exerting destructive effects on macromolecules, while the vb_EcoS_bov25_1D bacteriophage has a specific lytic action. Both, bacteriophages and Sakai were sensitive against ROS if tested separately, during that PFUs of bacteriophages dropped from 5 × 105 to 0 in 4 h, while in case of Sakai CFUs decreased with 5 and 2 logs of magnitude in the presence of 0,05 % and 0,025 % of TiO2 respectively. In Sakai by the sixth minute of ROS exposition the expressions of superoxide dismutases and catalases were boosted, as revealed by whole transcriptomic analyses, but the elevated levels rclC and bshA support some roles of these genes under this stress situation. Combined application of phages and TiO2 under UV-A exposure have revealed that beside the inner enzymatic defence mechanisms presenting phage particles served as shields and spoiled the antimicrobial effect of TiO2 (0,0125 %). As a consequence, phages became sacrificed as during exposition a 3-log drop (5 × 105→5 × 102) in their PFUs was revealed. Survived bacteriophages however in the system remained active and under the subsequent dark phase the 3-log drop in the PFU was compensated in 24 h. Our results show that joint application of the two alternative antimicrobial agents TiO2 and a bacteriophage can have two consequences depending on the circumstances they were used. From one side they complement each other's effects in that TiO2 can exert its effect on UV-A or sunlight exposed areas, whereas the bacteriophage on non-exposed surfaces. On the other hand, they also can spoil each others effect as phages can bind generated ROS and by that protect target bacteria, but bacteria themselves can serve as shields and by that protect phages from the destroying effect of ROS, phages however can exert their antibacterial effects on bacteria.

Pulsed corneal crosslinking in the treatment of Keratoconus: a systematic review and meta-analysis.

PURPOSE: Corneal crosslinking (CXL) procedures are the treatment of choice in halting progressive corneal ectasia and preserving visual acuity due to keratoconus. Pulsed crosslinking (P-CXL) was developed using intermittent pulsing ultraviolet (UV) light to mitigate the depletion of oxygen levels that occurs with continuous UV exposure in standard crosslinking protocols (C-CXL). This study aimed to explore the use of P-CXL in the treatment of keratoconus and determine whether the availability of oxygen in P-CXL carries superior efficacy outcomes as an alternative to C-CXL modalities. METHODS: This review was undertaken in accordance with PRISMA guidelines. A search of several databases conducted with two separate reviewers resulted in 29 papers meeting inclusion criteria for the review, 14 selected for meta-analysis. Primary outcomes assessed by the included papers included maximum keratometry (Kmax), corrected and uncorrected distance visual acuity (CDVA, UDVA), and secondary outcomes included central corneal thickness (CCT), endothelial cell count and demarcation line. Statistical analyses were carried out on Review Manager 5.4 and the meta-analysis employed a random-effects model, which estimated the weighted effect size of raw means using inverse variance weights. RESULTS: At 12 months P-CXL showed statistically significant reductions in Kmax (-0.75 D; p < 0.001) and improvement in CDVA (-0.10 logMAR; p < 0.001) compared to baseline. The meta-analysis of comparative studies determined that mean differences in Kmax, CDVA, UDVA, Kmean and CCT after 12 months were not statistically significant between pulsed and continuous crosslinking groups. CONCLUSIONS: Overall, P-CXL is effective in improving visual acuity and keratometry outcomes in keratoconus. The meta-analysis did not show a statistically significant difference in Kmax and CDVA between P-CXL and C-CXL, indicating a non-inferiority of P-CXL. However, findings of the meta-analysis are limited by the fact that different energy levels and exposure times were used for P-CXL in comparison to C-CXL in some studies, making it unsuitable to determine whether the efficacy of CXL is improved by the use of pulsed light. KEY MESSAGES: What is Known • Pulsed crosslinking (P-CXL) uses intermittent UV light to prevent oxygen depletion when using higher energy protocols, unlike continuous UV exposure in standard continuous crosslinking (C-CXL). • This should theoretically enhance the efficacy of the treatment by maintaining higher oxygen levels that are crucial to the cross-linking process. • There are no systematic reviews or meta-analyses directly comparing the efficacy or safety of P-CXL to C-CXL. What is New • Meta-analysis revealed differences in keratometry between P-CXL and C-CXL groups with equivalent fluence (7.2 J/cm2) at 12 months were not statistically significant (Kmax -0.04 dioptres; p = 0.84). • Meta-analysis revealed differences in visual acuity between P-CXL and C-CXL groups with equivalent fluence (7.2 J/cm2) at 12 months were not statistically significant (CDVA -0.01 logMAR letters; p = 0.57). • The use of intermittent pulsing in higher energy CXL protocols renders statistically similar outcomes as continuous light exposure at equivalent fluence (7.2 J/cm2).

Degradation of antipyrine in water with activated persulfate aided with biochar of olive pomace.

The degradation of antipyrine (AP) in water has been studied using persulfate activated with biochar obtained from gasification of olive pomace (BC) combined with ferric salts in the presence of UV-A radiation. Firstly, the adsorption of AP on biochar was evaluated. The data were adjusted using various kinetic models verifying that AP adsorption on BC occurs in three stages and follows pseudo-second order kinetics. Degradation tests show that the presence of iron or persulfate (PS) in binary systems with BC produces increases AP degradation when no radiation is used, reaching 75.7 % due to the ability of BC to donate electrons. On the other hand, addition of PS showed an increase in efficiency in the presence of BC (up to 79%). For ternary systems the best result was found when UVA/PS/Fe was used (100% of AP degradation in 30 min). The addition of UV-A radiation to the BC/PS system improves the degradation of the contaminant by only 6.7%, while the presence of iron in the studied conditions does not cause any improvement. A Central Composite Factorial Design of experiments was used to optimize the UVA/BC/PS/Fe system, leading to an 89.3% AP degradation rate in 90 min (k = 0.0134 min-1) under optimal conditions ([Fe(III)] = 10 mg/L, [PS] = 379 mg/L, [BC] = 500 mg/L). Although the best results were obtained for the UVA/PS/Fe process without BC, systems based on BC/PS can be considered as an alternative in cloudy days or when simple processes are selected due to economical/technical reasons.

Topical nanoencapsulated cannabidiol cream as an innovative strategy combating UV-A-induced nuclear and mitochondrial DNA injury: A pilot randomized clinical study.

BACKGROUND: UV-A radiation contributes to photoaging/photocarcinogenesis by generating inflammation and oxidative damage. Current photoprotective strategies are limited by the availability/utilization of UV-A filters, highlighting an unmet need. Cannabidiol (CBD), having anti-inflammatory/antioxidant properties via regulation of nuclear erythroid 2-related factor, heme oxygenase 1, and peroxisome proliferator-activated receptor gamma, could potentially mitigate damage from UV-A exposure. OBJECTIVE/METHODS: This is a prospective, single-center, pilot clinical trial (NCT05279495). Nineteen participants applied nano-CBD (nCBD) or vehicle (VC) cream to randomized, blinded buttock sites twice daily for 14 days; then, the treated sites were irradiated with ≤3× UV-A minimal erythema dose. After 24 hours, punch biopsies were obtained for histology, immunohistochemistry, and real-time polymerase chain reaction. RESULTS: At 24 hours, 21% of participants had less observed erythema on CBD-treated skin than on VC skin. Histologically, nCBD-treated skin had reduced UV-A-induced epidermal hyperplasia than VC (P = .01). Immunohistochemistry detected reduced cytoplasmic/nuclear 8-oxoguanine glycosylase 1 staining in nCBD-treated skin compared with VC (P < .01). Quantitative mtDNA polymerase chain reaction demonstrated that UV-A-induced deletion of ND4 (proxy:4977 bp deletion; P = .003) and ND1 (proxy:3895 bp deletion; P = .002) was significantly reduced by in vivo nCBD treatment compared with VC. LIMITATIONS: Small sample size is this study's limitation. CONCLUSION: Topically applied nCBD cream reduced UV-A-induced formation of a frequent mutagenic nuclear DNA base lesion and protected against mtDNA mutations associated with UV-A-induced skin aging. To our knowledge, this trial is the first to identify UV-protective capacity of CBD-containing topicals in humans.

Synthesis and characterization of X (X = Ni or Fe) modified BaTiO3 for effective degradation of Reactive Red 120 dye under UV-A light and its biological activity.

For the sustainable advancement of industrial expansion that is environmentally conscious, harmful dyes must be removed from wastewater. Untreated effluents containing colors have the potential to harm the ecosystem and pose major health risks to people, animals, and aquatic life. Here, we have fabricated Ni or Fe modified with BaTiO3 materials and effectively utilized them for Reactive Red 120 (RR 120) dye degradation under UV-A light. The synthesized materials were characterized, and their structural, and photo-physical properties were reported. Phase segregation was not present in the XRD pattern, as evidenced by the absence of secondary phase peaks linked to iron, nickel, or oxides. Low metal ion concentrations may be the cause of this, and the presence of those elements was confirmed by XPS measurements. The Raman spectra of the BaTiO3/Ni and BaTiO3/Fe samples show a widened peak at 500 cm-1, which suggests that Ni or Fe are efficiently loaded onto the BaTiO3. RR 120 dye photodegradation under UV light conditions was effectively catalyzed by BaTiO3/Fe, as evidenced by its superior performance in the UV irradiation technique over both BaTiO3 and BaTiO3/Ni. Compared to bare BaTiO3, both metal-modified materials efficiently degraded the RR 120 dye. Acidic pH facilitated the degradation process, which makes sense given that the heterogeneous photo-Fenton reaction was the mechanism of degradation along with BaTiO3 sensitization. High-acidity sewage can be dangerous and carcinogenic, and conventional biological treatment methods are not appropriate for managing it. In the current investigation, it may be used to treat color effluents with extremely low pH levels. Additionally, the ability of the produced nanocomposites to inhibit the growth of twenty pathogens was examined, along with two fungi, fifteen Gram-negative Bacilli (GNB), one Gram-positive Bacilli (GPB), and two Gram-positive Cocci (GBC).

Exploring the complexities of plant UV responses; distinct effects of UV-A and UV-B wavelengths on Arabidopsis rosette morphology.

UV-B radiation can substantially impact plant growth. To study UV-B effects, broadband UV-B tubes are commonly used. Apart from UV-B, such tubes also emit UV-A wavelengths. This study aimed to distinguish effects of different UV-B intensities on Arabidopsis thaliana wildtype and UVR8 mutant rosette morphology, from those by accompanying UV-A. UV-A promotes leaf-blade expansion along the proximal-distal, but not the medio-lateral, axis. Consequent increases in blade length: width ratio are associated with increased light capture. However, petiole length is not affected by UV-A exposure. This scenario is distinct from the shade avoidance driven by low red to far-red ratios, whereby leaf blade elongation is impeded but petiole elongation is promoted. Thus, the UV-A mediated elongation response is phenotypically distinct from classical shade avoidance. UV-B exerts inhibitory effects on petiole length, blade length and leaf area, and these effects are mediated by UVR8. Thus, UV-B antagonises aspects of both UV-A mediated elongation and classical shade avoidance. Indeed, this study shows that accompanying UV-A wavelengths can mask effects of UV-B. This may lead to potential underestimates of the magnitude of the UV-B induced morphological response using broadband UV-B tubes.

Mixed Metal Oxide W-TiO2 Nanopowder for Environmental Process: Synergy of Adsorption and Photocatalysis.

A mixed metal oxide W-TiO2 nanopowder photocatalyst was prepared by using the sol-gel method with a broad range of elemental compositions x = CW/(CW + CTi), including TiO2 and WO3. The material was structurally characterized and evaluated in adsorption and photocatalytic processes by testing its removal capacity of a representative pollutant methylene blue (MB) in aqueous solutions and under UV-A and sunlight illuminations. The nanopowders appeared to be more effective adsorbents than pure TiO2 and WO3 materials, showing a maximum at 15 mol% W, which was set as the tungsten solubility limit in anatase titania. At the same time, the photocatalytic decomposition of MB peaked at 2 mol% W. The examination of different compositions showed that the most effective MB removal took place at 15 mol% W, which was attributed to the combined action of adsorption and heterogeneous photocatalysis. Moreover, MB decomposition under sunlight was stronger than under UV-A, suggesting photocatalyst activation by visible light. The pollutant removal efficiency of the material with 15 mol% W was enhanced by a factor of ~10 compared to pure TiO2 at the beginning of the process, which shows its high potential for use in depollution processes in emergency cases of a great pollutant leak. As a result, a Wx=0.15-TiO2 catalyst could be of high interest for wastewater purification in industrial plants.

Effect of UV-A Irradiation on Bioactive Compounds Accumulation and Hypoglycemia-Related Enzymes Activities of Broccoli and Radish Sprouts.

In the present study, different intensities of UV-A were applied to compare their effects on growth, bioactive compounds and hypoglycemia-related enzyme activities in broccoli and radish sprouts. The growth of sprouts was decreased after UV-A irradiation. A total of 12 W of UV-A irradiation resulted in the highest content of anthocyanin, chlorophyll, polyphenol and ascorbic acid in broccoli and radish sprouts. The highest soluble sugar content was recorded in sprouts under 8 W of UV-A irradiation, while no significant difference was obtained in soluble protein content among different UV-A intensities. Furthermore, 12 W of UV-A irradiation induced the highest glucosinolate accumulation, especially glucoraphanin and glucoraphenin in broccoli and radish sprouts, respectively; thus, it enhanced sulforaphane and sulforaphene formation. The α-amylase, α-glucosidase and pancrelipase inhibitory rates of two kinds of sprouts were enhanced significantly after UV-A irradiation, indicating UV-A-irradiation-treated broccoli and radish sprouts have new prospects as hypoglycemic functional foods.

Recent insights into extracorporeal photopheresis for graft-versus-host disease.

INTRODUCTION: Extracorporeal Photopheresis (ECP) may be considered the unique large-scale cell therapy currently available. It is currently employed mainly as second-line treatment, especially in steroid-resistant or steroid-dependent Graft versus Host Disease (GvHD) with good results and very few limitations. AREAS COVERED: Many points need to be clarified regarding the ECP mechanism of action, that conditions the lack of uniqueness among the different centers, essentially cycle frequency, treatment duration, and the number of cells to be treated to obtain a response, according to the organs involved. Moreover, reliable biomarkers for prediction of response are lacking, as well as the best pharmacological combination. We will focus on the recent advances concerning ECP for GvHD treatment. We performed a systematic literature research in Pubmed and Embase as of September 2023. EXPERT OPINION: The recent studies on ECP mechanism of action along with the promising biomarkers of response, and the synergistic benefit of ECP in association with the new drugs render this therapy an important weapon for GvHD resistant to conventional treatment and can be proposed as a valid first-line therapy option with promising results. We believe that it should be used early in all categories of patients, considering its high safety profile.

Technical note: A preliminary assessment of UV-C imaging using the Full Spectrum Imaging System (FSIS-II) for the detection of latent fingermarks.

The Full Spectrum Imaging System (FSIS-II) was assessed for the detection of latent fingermarks on a variety of substrates, specifically focusing on UV-C imaging for untreated marks and those that have been treated with cyanoacrylate (CA). The use of UV-C was effective at the detection of latent fingermarks on a variety of substrates and UV-C imaging may be effective when UV-A does not provide any fingermark detections on thermal paper. A Phase 2 and a small Phase 3 trials on aluminium cans were carried out with a detection sequence of UV-C imaging, CA fuming, UV-C imaging, UV-A imaging and BY40. For Phase 2 laboratory trials, the use of initial UV-C reflection was effective at removing the background and was a useful tool for initial screening. The use of UV-C was superior to UV-A after CA fuming and provided the highest overall number of high-quality marks. For phase 3 trials, the results showed that BY40 fluorescence was marginally more effective than UV-C imaging of CA-treated marks. This preliminary study shows that the FSIS-II and UV-C imaging can complement other methods for the detection of latent fingermarks.

The comparative effects of visible light and UV-A radiation on the combined toxicity of P25 TiO2 nanoparticles and polystyrene microplastics on Chlorella sp.

The ubiquitous presence of TiO2 nanoparticles (nTiO2) and microplastics (MPs) in marine ecosystems has raised serious concerns about their combined impact on marine biota. This study investigated the combined toxic effect of nTiO2 (1 mg/L) and NH2 and COOH surface functionalized polystyrene MPs (PSMPs) (2.5 and 10 mg/L) on Chlorella sp. All the experiments were carried out under both visible light and UV-A radiation conditions to elucidate the impact of light on the combined toxicity of these pollutants. Growth inhibition results indicated that pristine nTiO2 exhibited a more toxic effect (38%) under UV-A radiation when compared to visible light conditions (27%). However, no significant change in the growth inhibitory effects of pristine PSMPs was observed between visible light and UVA radiation conditions. The combined pollutants (nTiO2 + 10 mg/L PSMPs) under UV-A radiation exhibited more growth inhibition (nTiO2 + NH2 PSMPs 66%; nTiO2 + COOH PSMPs 50%) than under visible light conditions (nTiO2 + NH2 PSMPs 55%; TiO2 + COOH PSMPs 44%). Independent action modeling indicated that the mixture of nTiO2 with PSMPs (10 mg/L) exhibited an additive effect on the algal growth inhibition under both the light conditions. The photoactive nTiO2 promoted increased production of reactive oxygen species under UV-A exposure, resulting in cellular damage, lipid peroxidation, and impaired photosynthesis. The effects were more pronounced in case of the mixtures where PSMPs added to the oxidative stress. The toxic effects of the binary mixtures of nTiO2 and PSMPs were further confirmed through the field emission electron microscopy, revealing specific morphological abnormalities. This study provides valuable insights into the potential risks associated with the combination of nTiO2 and MPs in marine environments, considering the influence of environmentally relevant light conditions and the test medium.

A Vicious NGF-p75NTR Positive Feedback Loop Exacerbates the Toxic Effects of Oxidative Damage in the Human Retinal Epithelial Cell Line ARPE-19.

In spite of its variety of biological activities, the clinical exploitation of human NGF (hNGF) is currently limited to ocular pathologies. It is therefore interesting to test the effects of hNGF in preclinical models that may predict their efficacy and safety in the clinical setting of ocular disorders and compare the effects of hNGF with those of its analogs. We used a human retinal pigment cell line, ARPE-19 cells, to investigate the effects of hNGF and its analogs, mouse NGF (mNGF) and painless NGF (pNGF), on cell viability under basal conditions and after exposure to oxidative stimuli, i.e., hydrogen peroxide (H2O2) and ultraviolet (UV)-A rays. The effects of hNGF and pNGF were also tested on the gene expression and protein synthesis of the two NGF receptor subtypes, p75 neurotrophic receptors (p75NTR) and tyrosine kinase A (TrkA) receptors. We drew the following conclusions: (i) the exposure of ARPE-19 cells to H2O2 or UV-A causes a dose-dependent decrease in the number of viable cells; (ii) under baseline conditions, hNGF, but not pNGF, causes a concentration-dependent decrease in cell viability in the range of doses 1-100 ng/mL; (iii) hNGF, but not pNGF, significantly potentiates the toxic effects of H2O2 or of UV-A on ARPE-19 cells in the range of doses 1-100 ng/mL, while mNGF at the same doses presents an intermediate behavior; (iv) 100 ng/mL of hNGF triggers an increase in p75NTR expression in H2O2-treated ARPE-19 cells, while pNGF at the same dose does not; (v) pNGF, but not hNGF (both given at 100 ng/mL), increases the total cell fluorescence intensity for TrkA receptors in H2O2-treated ARPE-19 cells. The present findings suggest a vicious positive feedback loop through which NGF-mediated upregulation of p75NTR contributes to worsening the toxic effects of oxidative damage in the human retinal epithelial cell line ARPE-19. Looking at the possible clinical relevance of these findings, one can postulate that pNGF might show a better benefit/risk ratio than hNGF in the treatment of ocular disorders.

Interaction of Rosmarinus officinalis L. with UV-A radiation by preserving its morphological traits and modifying its phenolic composition.

This study investigated the effects of supplemental ultraviolet-A (UV-A) radiation on phenolic compounds, antioxidant properties, and agro-morphological characteristics of Rosmarinus officinalis L. Greenhouse plants were exposed to UV-A for 1, 2, and 4 h daily, 40 days. Based on the results, UV-A radiation had no significant effect on agro-morphological traits, while it remarkably altered chlorophyll content, total phenolic and flavonoid contents, as well as radical scavenging activity. Plants exposed to UV-A (4h) had the highest total phenolic and flavonoid contents, antioxidant activity, as well as the content of rosmarinic, carnosic, vanillic, and caffeic acids, and naringin. Conversely, carnosol, cirsimaritin, and hispulin levels decreased in treated plants. Overall, UV-A radiation had a positive effect on the medicinal aspects of R. officinalis L., which is important in the pharmaceutical industry. Therefore, it is suggested application of UV-A emitting LEDs for commercial purposes, with a lower risk level than UV-B and UV-C.

Indoor Air Pollutant (Toluene) Reduction Based on Ultraviolet-A Irradiance and Changes in the Reactor Volume in a TiO2 Photocatalyst Reactor.

This study experimentally confirmed the effect of TiO2 photocatalysts on the removal of indoor air pollutants. In the experiment, toluene, a representative indoor air pollutant, was removed using a coating agent containing TiO2 photocatalysts. Conditions proposed by the International Organization for Standardization (ISO) were applied mutatis mutandis, and a photoreactor for an experiment was manufactured. The experiment was divided into two categories. The first experiment was conducted under ISO conditions using the TiO2 photocatalyst coating agent. In the second experiment, the amount of ultraviolet-A (UV-A) light was varied depending on the lamp's service life, and the volume of the reactor was varied depending on the number of contaminants. The results showed that the TiO2 photocatalytic coating agent reduced the effect of toluene. This reduction effect can be increased as a primary function depending on the changes in the amount of UV-A light and reactor volume. However, because toluene is decomposed in this study, additional organic pollutants such as benzene and butadiene can be produced. Because these pollutants are decomposed by the TiO2 photocatalysts, the overall reduction performance may change. Nonetheless, TiO2 photocatalysts can be used to examine the effect of indoor pollutant reduction in indoor ventilation systems and building materials.