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Ultraviolet B Radiation (ultraviolet + b_radiation)
Selected AbstractsUltraviolet B Radiation of Human Skin Generates Platelet-activating Factor Receptor AgonistsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2010Jared B. Travers Ultraviolet B radiation (UVB) is a potent stimulator of epidermal cytokine production. In addition to cytokines, such as tumor necrosis factor-alpha (TNF-,), UVB generates bioactive lipids including platelet-activating factor (PAF). Our previous in vitro studies in keratinocytes or epithelial cell lines have demonstrated that UVB-mediated production of PAF agonists is due primarily to the pro-oxidative effects of this stimulant, resulting in the nonenzymatic production of modified phosphocholines (oxidized glycerophosphocholines). The current studies use human skin to assess whether UVB irradiation generates PAF-receptor agonists, and the role of oxidative stress in their production. These studies demonstrate that UVB irradiation of human skin results in PAF agonists, which are blocked by the antioxidant vitamin C and the epidermal growth factor receptor inhibitor PD168393. Inasmuch as UVB-generated PAF agonists have been implicated in animal model systems as being involved in photobiologic processes including systemic immunosuppression and cytokine (TNF-,) production, these studies indicate that this novel activity could be involved in human disease. [source] Impairment of Eye Lens Cell Physiology and Optics by Broadband Ultraviolet A,Ultraviolet B Radiation,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2002O. M. Oriowo ABSTRACT The phototoxicity of ultraviolet A (UVA) alone and UVA plus ultraviolet B (UVB) combined on cultured porcine lenses was investigated by analyzing cellular function as measured with a fluorescence bioassay approach and optical integrity, in terms of sharpness of the lens focus as measured with a scanning laser system. The bioassay consisted of carboxyfluorescein diacetate-acetoxymethyl ester and alamarBlue fluorescent dyes. Aseptically dissected porcine lenses were maintained in modified medium 199 without phenol red supplemented with 1% penicillin,streptomycin and 4% porcine serum. At 1 week of preincubation, baseline measurements were obtained. Then the lenses were treated with single exposures of different UVA and UVB energy levels. The lenses treated with 86 J/cm2 UVA alone showed a significant (P < 0.05) decrease in cellular and optical integrity at 48 h after exposure, whereas those treated with 43 J/cm2 UVA alone did not show significant phototoxic effect. Lenses treated with 15.63 J/cm2 UVA plus 0.019 J/cm2 UVB combined showed significant adverse effects beginning from 48 h after exposure. Also, there was no recovery. These findings show that a high UVA dose alone and relatively low UVA in combination with low UVB radiant exposure can impair lens cellular and optical functions, respectively. [source] Activation of HIV in Human Skin by Ultraviolet B Radiation and its Inhibition by NF,B Blocking Agents,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2001Joan Breuer-McHam ABSTRACT To determine whether ultraviolet B (UVB) irradiation leads to activation of HIV in human skin, we conducted prospective and controlled studies in two academic medical centers in Texas from July 1995 to April 1999. HIV-positive patients with UV-treatable skin diseases were enrolled at each center, 18 subjects at one and 16 at the other. In one center, specimens from lesional and nonlesional skin biopsies were taken before and after sham- or UVB-irradiation administered in vivo or in vitro. In the other center, UVB phototherapy was administered three times weekly and specimens from skin biopsies were taken before and after 2 weeks (six treatments). Cutaneous HIV load was assessed using reverse transcriptase-polymerase chain reaction and reverse transcriptase-polymerase chain reaction in situ hybridization. UVB irradiation led to a 6,10-fold increase in the number of HIV in skin. To ascertain a role for nuclear factor kappa B (NF,B) in UVB-inducible HIV activation, two types of blockers, NF,B oligonucleotide decoy and sodium salicylate, were tested; each inhibited UVB-inducible HIV activation in skin partially. We conclude that UVB irradiation leads to increased numbers of HIV in human skin via processes that include release of cytoplasmic NF,B. [source] Ultraviolet B Radiation of Human Skin Generates Platelet-activating Factor Receptor AgonistsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2010Jared B. Travers Ultraviolet B radiation (UVB) is a potent stimulator of epidermal cytokine production. In addition to cytokines, such as tumor necrosis factor-alpha (TNF-,), UVB generates bioactive lipids including platelet-activating factor (PAF). Our previous in vitro studies in keratinocytes or epithelial cell lines have demonstrated that UVB-mediated production of PAF agonists is due primarily to the pro-oxidative effects of this stimulant, resulting in the nonenzymatic production of modified phosphocholines (oxidized glycerophosphocholines). The current studies use human skin to assess whether UVB irradiation generates PAF-receptor agonists, and the role of oxidative stress in their production. These studies demonstrate that UVB irradiation of human skin results in PAF agonists, which are blocked by the antioxidant vitamin C and the epidermal growth factor receptor inhibitor PD168393. Inasmuch as UVB-generated PAF agonists have been implicated in animal model systems as being involved in photobiologic processes including systemic immunosuppression and cytokine (TNF-,) production, these studies indicate that this novel activity could be involved in human disease. [source] Ultraviolet B radiation suppresses Langerhans cell migration in the dermis by down-regulation of ,4 integrinPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2006Motoko Hamakawa Background/Purpose: Ultraviolet B (UVB) radiation affects the migration and function of epidermal Langerhans cells (LC) and causes immunosuppression of contact hypersensitivity. It is known that LC leaves the epidermis after exposure to UVB. To know the behavior of LC in the dermis after UVB radiation, we studied the effect of UVB radiation on the expression of integrin families on freshly isolated or cultured murine LC. We also examined whether UVB radiation affects the migration of LC to secondary lymphoid tissue chemokine (SLC/6Ckine). Methods: Integrin expressions of murine LC cultured in epidermal cell suspension were analyzed using flowcytometry. We used murine LC sorted flowcytometrically for binding assay to extracellular matrix and for migration assay to chemokine. Skin explant assay and immnohistochemical staining for ,cords formation' were performed as previously described. Results: Twenty and 40 mJ/cm2 of UVB radiation down-regulated the expression of ,4 integrin on 24 h-cultured LC, but not that of ,6, ,1, or ,4 integrin. The number of cultured LC adhered to fibronectin, a ligand for ,4 integrin, was decreased after UVB irradiation, while that to laminin, a ligand for ,6 integrin, was not influenced. UVB radiation reduced the number of migrating LC to SLC. Furthermore, skin sheet explant experiments showed that UVB radiation inhibited the ,cords' formation in dermal vessels of the 48 h-cultured skin. Conclusions: These data suggest that UVB radiation may suppress the migration of LC from the dermis to lymphatic vessels. UVB radiation may downregulate the adherence of LC to dermal fibronectin and migration to SLC, and consequently suppress the migration of LC from the UVB-irradiated dermis to lymphatics. [source] Ultraviolet B radiation improves serum levels of vitamin D in patients with cystic fibrosisACTA PAEDIATRICA, Issue 5 2005Eva Gronowitz Abstract Background: Ultraviolet B (UVB) radiation can be used in the prevention and treatment of vitamin D deficiency. Aim: To investigate, in a controlled study of patients with cystic fibrosis (CF), whether regular UVB radiation would improve serum levels of calcidiol during the dark season (October,April). Methods: Thirty patients with mild to moderate disease were included (aged 9,40 y). All patients had cholecalciferol supplementation. One group (15 patients) was given UVB one to three times a week for 6 mo and one group (15 sex- and age-matched patients) served as controls. The radiation source consisted of three TL 12/40W UVB fluorescent lamps. Initial treatment duration was 1 min, subsequently increased by 0.5,1 min/treatment to a maximum of 10 min. Results: The mean initial serum calcidiol levels were 21 ng/ml in the controls and 22 ng/ml in the intervention group. Serum calcidiol levels increased to 44 ng/ml after 8 wk and to 50 ng/ml after 24 wk of UVB radiation; the corresponding serum levels in the controls were 19 and 25 ng/ml, respectively. The mean serum calcitriol levels increased in the treated group and were unaltered in the control group. Conclusions: UVB radiation was effective in increasing vitamin D levels in patients with CF. The study results imply that UVB radiation is valuable in chronic conditions associated with vitamin D deficiency. [source] Cooler temperatures increase sensitivity to ultraviolet B radiation in embryos and larvae of the frog Limnodynastes peroniiGLOBAL CHANGE BIOLOGY, Issue 6 2007VINCENT O. Van UITREGT Abstract Recent studies suggest that complex interacting processes are driving global amphibian declines. Increased ultraviolet B (UVB) radiation in the solar spectrum associated with ozone depletion has been implicated in declines, and evidence suggests that the effects of UVB radiation on amphibians may be greater at cooler temperatures. We tested the thermal sensitivity of UVB effects on amphibians in a controlled factorial experiment using the striped marsh frog, Limnodynastes peronii as a model species. We compared survival, growth and locomotor performance of embryonic and larval L. peronii reared under low and high UVB exposures at both 20 and 30 °C. Embryonic and larval L. peronii proved extremely sensitive to UVB damage and exhibited greater sensitivity at 20 °C compared with 30 °C. Embryonic survival to Gosner stage 25 was unaffected by UVB exposure at 30 °C, but at 20 °C survival was reduced to 52% under high UVB. Larval survival exhibited a similar trend. At 20 °C, all tadpoles survived under low UVB, whereas under high UVB there was 100% mortality after 15 days of exposure. At 30 °C, 86% survived under low UVB, but only 46% survived under high UVB. Sublethal effects such as, embryonic malformation, retarded larval growth and reduced larval swimming performance were also greater at 20 °C compared with 30 °C. Our results strongly indicate that UVB damage in amphibians is markedly increased at cooler temperatures. Thus, populations of UVB sensitive species occurring at cold climates may be at greater risk of declines due to increased solar UVB radiation. [source] Narrow-band ultraviolet B radiation: a review of the current literatureINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 8 2004Grace D. Bandow MD First page of article [source] Sensitivity of Crops to Increased Ultraviolet Radiation in Northern Growing ConditionsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2002K. Hakala Crops growing at high latitudes are adapted to low intensities of solar ultraviolet B radiation (UV-B). As a result of destruction of stratospheric ozone layer especially at the Polar Regions of the globe, the intensity of UV-B is projected to increase at high latitudes. In order to find out the consequences of increased UV-B on crops, the sensitivity of different varieties of barley, wheat, oats, clover, timothy, meadow fescue, tall fescue and potato was tested in Jokioinen, Finland. The experiment was conducted in the field, under natural light, with a continuous 30 % increase in UV-B. Both increased UV-B and the control with slightly increased UV-A radiation affected the number of lateral shoots in cereals, and the specific leaf area and the content of phenolic substances in grasses. The effects varied according to plant variety and time of growing season. However, no visible damage, nor changes in biomass and yield production were found in any of the crops. Long-term effects on, e.g. genetic stability and germination of crop seed remain to be studied. Empfindlichkeit von Kulturpflanzenbeständen gegenüber einer Erhöhung der ultravioletten Einstrahlung unter nördlichen Wachstumsbedingungen Kulturpflanzenbestände, die unter hohen Breitengraden wachsen, sind an geringe Intensitäten der solaren ultravioletten B Einstrahlung (UV-B) angepasst. Aufgrund der Destruktion der Stratosphäre, insbesondere der Ozonschicht, im Bereich der polaren Gebiete der Erde, ist eine zunehmende Intensität der UV-B Strahlung in hohen Breitengraden festzustellen. Um die Konsequenzen einer Erhöhung von UV-B auf Kulturpflanzenbestände zu bestimmen, wurde die Empfindlichkeit unterschiedlicher Arten wie Gerste, Weizen, Hafer, Klee, Wiesenlieschgras, Wiesenschwingel, Rohrschwingel und Kartoffel in Jokioinen, Finnland, untersucht. Das Experiment wurde im Felde durchgeführt unter natürlichen Lichtbedingungen mit einer kontinuierlichen Zunahme von 30 % für UV-B. Sowohl eine Erhöhung der UV-B als auch die Kontrolle mit leicht erhöhten UV-B Strahlungen beeinflussten die Anzahl der Nebenwurzeln bei den Getreidepflanzen und die spezifische Blattfläche sowie den Gehalt an phenolischen Substanzen bei den Gräsern. Die Wirkungen variierten entsprechend der Pflanzenvarietät und der Anbauzeit. Allerdings wurden keine erkennbare Schädigungen noch Änderungen in der Biomasse und in der Ertragsproduktion bei einer der untersuchten Pflanzenbestände gefunden. Langzeitwirkungen auf die genetische bedingte Stabilität und Keimung der Kulturpflanzen sollte weiterhin untersucht werden. [source] UVR8 in Arabidopsis thaliana regulates multiple aspects of cellular differentiation during leaf development in response to ultraviolet B radiationNEW PHYTOLOGIST, Issue 2 2009Jason J. Wargent Summary ,,Responses specific to ultraviolet B (UV-B) wavelengths are still poorly understood, both in terms of initial signalling and effects on morphogenesis. Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) is the only known UV-B specific signalling component, but the role of UVR8 in leaf morphogenesis is unknown. ,,The regulatory effects of UVR8 on leaf morphogenesis at a range of supplementary UV-B doses were characterized, revealing both UVR8-dependent and independent responses to UV irradiation. ,,Inhibition of epidermal cell division in response to UV-B is largely independent of UVR8. However, overall leaf growth under UV-B irradiation in wild-type plants is enhanced compared with a uvr8 mutant because of a UVR8-dependent compensatory increase of cell area in wild-type plants. UVR8 was also required for the regulation of endopolyploidy in response to UV-B, and the uvr8 mutant also has a lower density of stomata than the wild type in the presence of UV-B, indicating that UVR8 has a regulatory role in other developmental events. ,,Our findings show that, in addition to regulating UV-protective gene expression responses, UVR8 is involved in controlling aspects of leaf growth and morphogenesis. This work extends our understanding of how UV-B response is orchestrated at the whole-plant level. [source] Time series analysis of ultraviolet B radiation and type 1 diabetes in NewfoundlandPEDIATRIC DIABETES, Issue 2 2008Scott Sloka Background:, Type 1 diabetes mellitus (T1DM) has been previously been associated with decreased levels of vitamin D. This study investigates the temporal association between average daily ultraviolet B (UVB) irradiance and T1DM in Newfoundland. Methods:, A complete list of patients diagnosed with T1DM in the province of Newfoundland and Labrador was constructed using multiple sources. Pooled and unpooled monthly incidence data along with monthly UVB measurements were used to build a time series transfer function model. The model was used to predict the future incidence of T1DM based on previous monthly trends, and these predictions were compared with actual measured incidences. Results:, A seasonal variation in pooled monthly incidence was observed. The transfer function model was able to reasonably predict the future incidence of T1DM based on previous observations and monthly UVB measurements. Tests of seasonality demonstrated a significant seasonal trend (p = 0.0003). Conclusions:, This study suggests that erythemal UVB radiation may be temporally associated with the incidence of T1DM. [source] Temperature Effects on Survival and DNA Repair in Four Freshwater Cladoceran Daphnia Species Exposed to UV RadiationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2009Sandra J. Connelly The biological responses of four freshwater daphniid species, Daphnia middendorffiana, D. pulicaria, D. pulex and D. parvula, to a single acute dose of ultraviolet B radiation (UVB) were compared. In addition to survival, we compared the induction of DNA damage (i.e. cyclobutane pyrimidine dimers) between species as well as the ability to repair this damage in the presence or absence of photoreactivating light. All four species showed high levels of shielding against DNA damage when compared to damage induced in purified DNA dosimeters at the same time and dose. Significant variation in survival was observed between species depending on temperature and light conditions. Contrary to our expectations, all species showed significantly higher survival and light-dependent DNA damage removal rates at 10°C compared to 20°C, suggesting that the enhanced rate of photoenzymatic repair (PER) at the lower temperature contributed significantly to the recovery of these organisms from UVB. PER was highly effective in promoting survival of three of the four species at 10°C, but at 20°C it was only partially effective in two species, and ineffective in two others. None of the species showed significant dark repair at 20°C and only D. pulicaria showed a significant capacity at 10°C. Two species, D. middendorffiana and D. pulex, showed some short-term survival at 10°C in absence of PER despite their inability to repair any appreciable amount of DNA damage in the dark. All species died rapidly at 20°C in absence of PER, as predicted from complete or near-absence of nucleotide excision repair (NER). Overall, the protective effects of tissue structure and pigmentation were similar in all Daphnia species tested and greatly mitigated the absorption of UVB by DNA and its damaging effects. Surprisingly, the visibly melanotic D. middendorffiana was not better shielded from DNA damage than the three non-melanotic species, and in fact suffered the highest damage rates. Melanin content in this species was not temperature dependent under the experimental growth conditions, and so did not contribute to temperature-dependent responses. It is evident that different species within the same genus have developed diverse biological responses to UVB. Our data strongly suggest that DNA damage is lethal to Daphnia and that photoenzymatic repair is the primary mechanism for removing these lesions. In the absence of light, few species are capable of removing any DNA damage. Surprisingly, the single species in which significant excision repair was detected did so only at reduced temperature. This temperature-dependence of excision repair is striking and may reflect adaptations of certain organisms to stress in a complex and changing environment. [source] Ultraviolet A exposure might increase metastasis of mouse melanoma: a pilot studyPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2005Riikka Pastila Background: The major sources of long-wave ultraviolet A radiation (UVA; 320,400 nm) exposure are extensive sunbathing and tanning in solaria. While the carcinogenic effects of mid-wave ultraviolet B radiation (UVB; 280,320 nm) are well recognized, the potentially hazardous effects of UVA are less understood. Several studies have shown that a variety of physiological processes in the cell are modified by UVA exposure, some of which might be involved in the regulation of tumor metastasis. In this study we suggest that UVA radiation could lead to the increase of metastatic capability of melanoma cells in mice. Method/result: A pilot in vivo study was executed using C57BL/6 mice and syngeneic B16 melanoma cell lines. Mice were intravenously (i.v.) injected with either B16-F1 or B16-F10 melanoma cells into the tail vein and then immediately exposed to UVA. Fourteen days after melanoma injection, lungs were collected and the quantity and quality of metastases were determined under a dissecting microscope. As an outcome of the pilot study we observed that i.v. injected melanoma cells formed more lung metastases in the UVA-exposed mice in comparison with the control mice. Conclusion: This result suggests that the UVA exposure of mice, with melanoma cells present in blood circulation, increases the formation of melanoma metastases in lungs. Further studies should determine whether a similar pro-metastatic effect, as observed in mice, could occur in humans and whether other than melanoma tumors might be susceptible. [source] Sunscreen protection in the ultraviolet A region: how to measure the effectivenessPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 1 2001C. Cole Products containing ultraviolet (UV) radiation absorbing or scattering ingredients provide varying degrees of protection from sunlight (or other UV sources), thus minimizing the deleterious effects on the skin. The "sun protection factor" (SPF) of sunscreen products has become a well recognized indicator of protection against sunburn induced predominantly by ultraviolet B radiation (UVB: 290,320 nm). A similar system of denoting sunscreen protection from ultraviolet A (UVA: 320,400 nm) radiation has not been universally recognized. A variety of test methods have been proposed, both in vitro and in vivo, each with specific virtues and shortcomings. Regulatory agencies and industry have been reviewing the available methods over the past decade in an effort to develop consumer meaningful claims and appropriate substantiation methods. This article reviews these test methodologies, in vitro and in vivo, as well as the biological background that establishes the need for UVA protection, and the UVA content of solar radiation and its variability. [source] | |||||||||||||