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UV Exposure (uv + exposure)
Selected AbstractsUV Exposure of Elementary School Children in Five Japanese Cities,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Masaji Ono ABSTRACT A 1 week UV-exposure measurement and outdoor-activity pattern survey was conducted for elementary school children for four seasons at five sites in Japan, i.e. Sapporo (43°05,N, altitude 40 m), Tsukuba (36°05,N, 20 m), Tokyo (35°40,N, 45 m), Miyazaki (31°60,N, 40 m) and Naha (26°10,N, 5 m), and UV exposure was measured directly and estimated using outdoor-activity records. The study site with largest UV exposure was Miyazaki, a southern rural area. Comparing the results for boys and girls, UV exposure was larger in boys. UV exposure was large in spring and summer and small in winter. The total amount of UV exposure in spring and summer contributed 57.7,73.4% of total exposure for the year. As a whole, 8.1% and 1.8% of the schoolchildren were exposed to more than 1 minimum erythemal dose (MED) and 2 MED of solar UV in a day, respectively. The estimated yearly UV exposure ranged from 49 207 J/m2 in Miyazaki to 31 520 J/m2 in Tsukuba. The actual UV exposure correlated to potential UV exposure, estimated using outdoor-activity records and ambient UV irradiance, but the ratio differed by season and site. The yearly average of percent UV exposure to ambient UV on a horizontal plane ranged from 9.9% in Tokyo to 4.0% in Naha. In the questionnaire survey on outdoor-activity pattern, a short question "How long did you spend time outdoors between 0900 and 1500 h?" gives the best estimates of UV exposure. [source] UV Exposure, Genetic Targets in Melanocytic Tumors and Transgenic Mouse Models,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2005Frank R. de Gruijl ABSTRACT The genetic changes and corruption of kinase activity in melanomas appear to revolve around a central axis: mitogenic signaling along the RAS pathway down to transcription regulation by pRB. Epidemiological studies point to the importance of ultraviolet (UV) radiation in the etiology of melanoma, but where and how UV radiation is targeted to contribute to the oncogenic signaling remains obscure. Animal models of melanoma genesis could serve to clarify this issue, but many of these models are not responsive to UV exposure. Most interesting advances have been made by using transgenic mice that carry genetic defects that are known to be relevant to human melanoma: specifically, dysfunction in the tumor suppressive action of p161NK4a or a receptor tyrosine kinase/RAS pathway, that is constitutively activated in melanocytes. The latter types of mice appear to be most responsive to (neonatal) UV exposure. Whether this is due to a general increase in target cells by melanocytosis and a paucity or complete lack of pigment, or a possible UV-induced response of the promoter,enhancer of the transgene or a genuinely independent and additional genetic alteration caused by UV exposure needs to be established. Importantly, the full effect of UV radiation needs to be ascertained in mice with different pigmentation by varying the wavelengths, UV-B versus UV-A1, and the exposure schedules, i.e. neonatal versus adult and chronic versus intermittent overexposure. Intermittent UV-B overexposure deserves special attention because it most strongly evokes proliferative responses in melanocytes. [source] Suppression of the mouse double minute 4 gene causes changes in cell cycle control in a human mesothelial cell line responsive to ultraviolet radiation exposureENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 9 2009Melisa Bunderson-Schelvan Abstract The TP53 tumor suppressor gene is the most frequently inactivated gene in human cancer identified to date. However, TP53 mutations are rare in human mesotheliomas, as well as in many other types of cancer, suggesting that aberrant TP53 function may be due to alterations in its regulatory pathways. Mouse double minute 4 (MDM4) has been shown to be a key regulator of TP53 activity, both independently as well as in concert with its structural homolog, Mouse Double Minute 2 (MDM2). The purpose of this study was to characterize the effects of MDM4 suppression on TP53 and other proteins involved in cell cycle control before and after ultraviolet (UV) exposure in MeT5a cells, a nonmalignant human mesothelial line. Short hairpin RNA (shRNA) was used to investigate the impact of MDM4 on TP53 function and cellular transcription. Suppression of MDM4 was confirmed by Western blot. MDM4 suppressed cells were analyzed for cell cycle changes with and without exposure to UV. Changes in cell growth as well as differences in the regulation of direct transcriptional targets of TP53, CDKN1A (cyclin-dependent kinase 1,, p21) and BAX, suggest a shift from cell cycle arrest to apoptosis upon increasing UV exposure. These results demonstrate the importance of MDM4in cell cycle regulation as well as a possible role inthe pathogenesis of mesothelioma-type cancers. Environ. Mol. Mutagen. 2009. © 2009 Wiley-Liss, Inc. [source] Improved Comet assay for the assessment of UV genotoxicity in Mediterranean sea urchin eggsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2008Sarah Nahon Abstract Gametes and embryos of broadcast spawners are exposed to a wide range of chemical and physical stressors which may alone, or in conjunction, have serious consequences on reproductive outcomes. In this study, two Mediterranean echinoid species, Paracentrotus lividus and Sphaerechinus granularis, were chosen as models to study the genotoxicity of UV radiation (UVR) on the eggs of broadcast-spawning marine invertebrates. The single cell gel electrophoresis, or Comet assay, was successfully adapted to assess DNA strand breakage in sea urchin eggs. The results demonstrated that the genetic material of sea urchin eggs is susceptible to environmentally realistic UV exposure. The induction of DNA damage in the irradiated unfertilized eggs suggests that the previously described defense mechanisms in sea urchin eggs do not completely protect the egg's DNA against UV toxicity. Taken together, our results suggest that UV-impairment of the genetic integrity of the eggs might have a role in postfertilization failures and abnormal embryonic development. Although both species were vulnerable to UVR, embryonic development was less dramatically impaired in P.Lividus. This observation supports the postulation that species inhabiting shallower environments possess more efficient mechanisms to overcome UV-induced DNA alterations. The present demonstration of the utility and sensitivity of the Comet assay to evaluate DNA integrity in eggs from marine invertebrates opens new perspectives for monitoring the long-term effects of environmental exposure on populations and for the routine screening of substances for genotoxicity in marine systems. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source] Vitamin D and skin: new aspects for dermatologyEXPERIMENTAL DERMATOLOGY, Issue 2004Bodo Lehmann Abstract:, It has been shown that epidermal keratinocytes have the capacity for the UVB-induced photochemical conversion of 7-dehydrocholesterol to vitamin D3, and also for the enzymatically controlled hydroxylation of the photolysis product. This metabolic loop results in the formation of the biologically active final product 1,,25-dihydroxyvitamin D3 (1,,25(OH)2D3, calcitriol). The epidermal synthesis of calcitriol is of fundamental relevance because calcitriol regulates important cellular functions in keratinocytes and immunocompetent cells. Because of their anti-proliferative and prodifferentiating effects, calcitriol and other vitamin D analogs are highly efficient in the treatment of psoriasis vulgaris. In addition, the known therapeutic effect of UVB light therapy in the treatment of psoriasis may, at least in part, be mediated via UVB-induced synthesis of calcitriol. Increasing evidence now indicates that cutaneous vitamin D synthesis is of great importance for the prevention of a broad variety of diseases, including various malignancies. It has been postulated that cancer mortality could be reduced via careful UV exposure or, more safely, via oral substitution with vitamin D. These new findings must be taken into account when establishing new sun protection guidelines for the prevention of skin cancer. In addition, better understanding of the metabolism of vitamin D in the skin has opened up new perspectives for the therapeutic application of vitamin D analogs, e.g. in inflammatory skin diseases. [source] Effects of ultraviolet radiation on the eggs of landlocked Galaxias maculatus (Galaxiidae, Pisces) in northwestern PatagoniaFRESHWATER BIOLOGY, Issue 3 2000M. Battini Summary 1Ultraviolet radiation (UVR) damages early life stages of several fish species. Galaxias maculatus is a small catadromous fish, with landlocked forms occurring in many lakes within the Nahuel Huapi National Park (Patagonia, Argentina). In this work, the vulnerability of G. maculatus eggs exposed to both natural and artificial UVR was investigated in relation to water transparency. 2Field experiments were performed in two lakes differing in UVR attenuation. Galaxias maculatus eggs were exposed to in situ levels of UVR in quartz tubes incubated at various depths. For laboratory experiments, the eggs were exposed to five levels of artificial UVB radiation. 3Exposure to natural UVR causes various degrees of egg mortality depending on water transparency and incubation depth. In the less transparent lake (Kd320 = 3.08 m -1), almost complete mortality was observed near the surface. At a depth of 43 cm the observed mortality was only 22%, but was still significantly different from the dark control. In the most transparent lake (Kd320 = 0.438 m -1), almost total mortality was observed in tubes incubated at 2.56 m or shallower. A gradual decline in mortality was recorded from that depth to 3.78 m where the values approached those in the dark control treatments. 4A monotonic relationship between mortality and UV exposure could be observed both in field and laboratory experiments. Using the results from field incubations, a LD50 of 2.5 J cm -2 nm -1 was estimated. In a few mountain lakes, this value would be exceeded even if the eggs were laid at the maximum depth of the lake. Thus UVR seems a sufficient cause to explain the absence of G. maculatus populations in some mountain lakes. For most lakes, however, UVR is probably one of several important environmental factors, which together determine the habitat suitability. [source] Effects of ultraviolet radiation on litter decomposition depend on precipitation and litter chemistry in a shortgrass steppe ecosystemGLOBAL CHANGE BIOLOGY, Issue 10 2007LESLIE A. BRANDT Abstract We examined the effect of altered levels of ultraviolet (UV) radiation (280,400 nm) and different amounts of precipitation on the decomposition rates of litter of contrasting carbon to nitrogen ratio (C : N) in a 3-year field experiment in a shortgrass steppe (SGS) ecosystem. UV radiation was either blocked or passed under clear plastic tents where precipitation was applied to simulate a very dry or very wet year. These treatments minimized or maximized the abiotic component (UV) or the biotic component (biological activity of decomposer organisms) of decomposition to assess potential interactions between the two. Initial litter chemistry varied in response to having been grown under ambient or elevated atmospheric CO2 concentrations. While precipitation and litter chemistry were the most important drivers in decomposition in this system, UV radiation increased decomposition rates under dry conditions in litter with higher C : N ratios. Exposure to UV radiation slightly increased the amount of holocellulose that was lost from the litter. UV exposure did not affect the decomposition of the lignin fraction. Increased decomposition with UV radiation was accompanied by a decrease in N immobilization over the summer months. These results suggest that the effects of UV radiation on decomposition rates may be primarily abiotic, caused by direct photochemical degradation of the litter. Our results demonstrate that the role of UV radiation in litter decomposition in semiarid systems depends on the aridity of the system and the chemistry of the litter. [source] Tuning and Transcription of the Supramolecular Organization of a Fluorescent Silsesquioxane Precursor into Silica-Based Materials through Direct Photochemical Hydrolysis,Polycondensation and MicropatterningADVANCED FUNCTIONAL MATERIALS, Issue 3 2009Xavier Sallenave Abstract A new fluorescent silsequioxane precursor with tuned optical properties and controlled aggregation properties is designed. The two cyclohexyl moieties introduced in the molecular structure allow the formation of very good quality films. The J-aggregated structure is transcribed into the solid by photoacid-catalyzed hydrolysis,polycondensation. Aggregation of the chromophores is reduced and highly fluorescent materials are obtained. The photoacid generator lies on the surface of the homogeneous layer of the sol,gel precursor. This phase separation presents several advantages, including UV protection of the chromophore and easy removal of the PAG. The first example of chemical amplification in the photolithography of the conjugated silsesquioxane precursor is demonstrated. As hydrolysis,polycondensation could be achieved in a controlled way by UV exposure, chemically amplified photolithography is achieved by irradiating a composite film (,110,nm thick) on silicon wafer by using a copper TEM grid as shadow mask. The pattern is produced uniformly on a miscroscopic scale of 3,mm, the photopatterned pixels remaining highly fluorescent. The sizes of the photolithographed pixels correspond to the sizes of the rectangular holes of the 300,×,75 mesh grid (hole: 63,<$>,<$>m,×,204,<$>,<$>m). [source] Molecular response to climate change: temperature dependence of UV-induced DNA damage and repair in the freshwater crustacean Daphnia pulicariaGLOBAL CHANGE BIOLOGY, Issue 4 2004Emily J. MacFadyen Abstract In temperate lakes, asynchronous cycles in surface water temperatures and incident ultraviolet (UV) radiation expose aquatic organisms to damaging UV radiation at different temperatures. The enzyme systems that repair UV-induced DNA damage are temperature dependent, and thus potentially less effective at repairing DNA damage at lower temperatures. This hypothesis was tested by examining the levels of UV-induced DNA damage in the freshwater crustacean Daphnia pulicaria in the presence and absence of longer-wavelength photoreactivating radiation (PRR) that induces photoenzymatic repair (PER) of DNA damage. By exposing both live and dead (freeze-killed) Daphnia as well as raw DNA to UV-B in the presence and absence of PRR, we were able to estimate the relative importance and temperature dependence of PER (light repair), nucleotide excision repair (NER, dark repair), and photoprotection (PP). Total DNA damage increased with increasing temperature. However, the even greater increase in DNA repair rates at higher temperatures led net DNA damage (total DNA damage minus repair) to be greater at lower temperatures. Photoprotection accounted for a much greater proportion of the reduction in DNA damage than did repair. Experiments that looked at survival rates following UV exposure demonstrated that PER increased survival rates. The important implication is that aquatic organisms that depend heavily on DNA repair processes may be less able to survive high UV exposure in low temperature environments. Photoprotection may be more effective under the low temperature, high UV conditions such as are found in early spring or at high elevations. [source] Ultraviolet-Assisted Direct-Write Fabrication of Carbon Nanotube/Polymer Nanocomposite MicrocoilsADVANCED MATERIALS, Issue 5 2010Louis Laberge Lebel The UV-assisted direct-write fabrication of microcoils is shown using a UV-photocurable carbon nanotube nanocomposite ink. The method employs the robotically controlled microextrusion of a filament combined with a UV exposure that follows the extrusion point. Upon curing, the increased rigidity of the extruded filament enables the creation of complex multi-directional shapes. [source] The association of use of sunbeds with cutaneous malignant melanoma and other skin cancers: A systematic reviewINTERNATIONAL JOURNAL OF CANCER, Issue 5 2007Article first published online: 27 NOV 200 Abstract Exposure to solar ultraviolet (UV) radiation is a known cause of skin cancer. Sunbed use represents an increasingly frequent source of artificial UV exposure in light-skinned populations. To assess the available evidence of the association between sunbed use and cutaneous malignant melanoma (melanoma) and other skin cancers, a systematic review of the literature till March 2006 on epidemiological and biological studies on sunbed use was performed in Pubmed, ISI Web of Science, Embase, Pascal, Cochrane library, Lilacs and Medcarib. Search for keywords in the title and in the abstract was done systematically and supplemented by manual searches. Only case,control, cohort or cross-sectional studies were selected. Data were abstracted by means of a standardized data-collection protocol. Based on 19 informative studies, ever-use of sunbeds was positively associated with melanoma (summary relative risk, 1.15; 95% CI, 1.00,1.31), although there was no consistent evidence of a dose,response relationship. First exposure to sunbeds before 35 years of age significantly increased the risk of melanoma, based on 7 informative studies (summary relative risk, 1.75; 95% CI, 1.35,2.26). The summary relative risk of 3 studies of squamous cell carcinoma showed an increased risk. For basal cell carcinoma, the studies did not support an association. The evidence does not support a protective effect of the use of sunbeds against damage to the skin from subsequent sun exposure. Young adults should be discouraged from using indoor tanning equipment and restricted access to sunbeds by minors should be strongly considered. © 2006 Wiley-Liss, Inc. [source] Improving cellular function through modulation of energy metabolismINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2004D. Maes The ambivalent consequences of mitochondrial stimulation on cellular activity have been well established. Mitochondria supply the cell with energy through a process of oxidative phosphorylation but thereby generate free radicals, resulting in the accumulation of hydrogen peroxide in the cytoplasm. We have investigated the impact of cellular senescence as well as UV irradiation, on the balance between these two activities. The adenosine triphosphate (ATP) level, DNA and protein synthesis in fibroblasts obtained from donors between 30 and 90 years of age appeared to be significantly influenced by the aging process. Both DNA and protein synthesis could be stimulated by increasing intracellular ATP levels. In-vitro senescent fibroblasts showed a reduction in the level of ATP as well as a shift in mitochondrial membrane potential. At the same time, there was an increase in intracellular hydrogen peroxide with increasing population doubling, indicating a clear dysfunction of the metabolic machinery in the mitochondria of senescent cells. To counteract this degradation of the energy pool, we treated cells with creatine, which is known to restore the pool of phosphocreatine in the mitochondria. Creatine treatment significantly increased cell survival after UV exposure, stimulated the repair of UVB-induced DNA damage in keratinocytes and caused a significant reduction in the number of sunburn cells in a UVB-exposed reconstituted skin model. These results clearly indicate that restoration of the energy pool in mitochondria increased cellular self-defense mechanism. These data show the important role played by the mitochondrial energy metabolism on the aging process, and indicate a possible therapy that can be used to counteract this negative effect. Treatment with creatine seems to provide the necessary boost to the cellular metabolism, which leads to an induction of a significant amount of protection and repair to human skin cells. [source] Effect of UV and hygrothermal aging on the mechanical performance of polyurethane elastomersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008H. Aglan Abstract In this study, the effects of environmental aging on the mechanical performance of elastomeric polyurethane (PU) were investigated using two accelerated aging techniques, namely, ultraviolet (UV) and hygrothermal (HT). Samples were prepared and subjected to UV and HT exposure for a period of 5 months and removed and mechanically tested at different time intervals. Differential scanning calorimetry (DSC) was performed. A noticeable change in the chemical structure of the PU after 1 month of UV exposure was found, however, that was not the case after 1 month of HT exposure. The stress and strain to failure, tearing energy, and storage modulus were evaluated at different intervals for both aging techniques. It was found that the UV exposure caused severe degradation of the PU in comparison with the HT. A reduction of more than 98% in the tearing energy was observed for the UV-exposed samples after 5 months when compared with only a 35% reduction in the tearing energy for the HT-exposed samples. A similar trend was observed for tear strength and storage modulus. The degradation mechanisms of the PU elastomers have been identified using SEM and correlated with the tearing energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A positive-working photosensitive polyimide based on thermal cross-linking and acidolytic cleavageJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Myung-Sup Jung Abstract A novel positive-working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three-component PSPI was synthesized from 4,4,-oxydiphthalic anhydride and 2,2,-bis(3-amino-4-hydroxyphenyl)hexafluoropropane through ring-opening polymerization and subsequent thermal cyclization. 2,2,-bis(4-(2-(vinyloxy)ethoxy)phenyl)propane (BPA-DEVE) was used as a vinylether compound and diphenyliodonium 5-hydroxynaphthalene-1-sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA-DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA-DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 ,m in a 3.7-,m-thick film was obtained from the three-component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Differential expression of the two distinct replication protein A subunits from Cryptosporidium parvumJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008Stanley Dean Rider Jr. Abstract Apicomplexan parasites differ from their host by possessing at least two distinct types (long and short) of replication protein A large subunits (RPA1). Different roles for the long and short types of RPA1 proteins have been implied in early biochemical studies, but certain details remained to be elucidated. In the present study, we have found that the Cryptosporidium parvum short-type RPA1 (CpRPA1A) was highly expressed at S-phase in parasites during the early stage of merogony (a cell multiplication process unique to this group of parasites), but otherwise present in the cytosol at a much lower level in other cell-cycle stages. This observation indicates that CpRPA1A is probably responsible for the general DNA replication of the parasite. On the other hand, the long-type CpRPA1B protein was present in a much lower level in the early life cycle stages, but elevated at later stages involved in sexual development, indicating that CpRPA1B may play a role in DNA recombination. Additionally, CpRPA1B could be up-regulated by UV exposure, indicating that this long-type RPA1 is probably involved in DNA repair. Collectively, our data implies that the two RPA1 proteins in C. parvum are performing different roles during DNA replication, repair and recombination in this parasite. J. Cell. Biochem. 104: 2207,2216, 2008. © 2008 Wiley-Liss, Inc. [source] Immune protective effect of a moisturizer with DNA repair ingredientsJOURNAL OF COSMETIC DERMATOLOGY, Issue 2 2008Cheré R Lucas MD Summary Ultraviolet (UV) light damages DNA and impairs immune surveillance. The faulty repair of DNA after UV exposure is associated with immune suppression and facilitates photodamage that leads to photoaged skin and the growth of skin cancer. Sunscreens have been developed to filter UV light from entering the skin, but are not beneficial once DNA damage has occurred. Enhancing DNA repair after UV radiation may provide added advantage and prevent UV immunosuppression. This study was performed to determine whether a product with DNA repair ingredients prevents UV-induced suppression of contact hypersensitivity responses in vivo. Solar simulated radiation was delivered on skin with and without topical treatment with a moisturizer containing DNA repair enzymes (Advanced Night Repair Concentrate). Subjects were then sensitized to the hapten dinitrochlorobenzene, and the level of resultant contact hypersensitivity response was elicited 2 weeks later. Contact hypersensitivity response measured by skin fold thickness was significantly suppressed in untreated UV-irradiated subjects but not in subjects treated with DNA repair moisturizer after solar simulated radiation. Our results indicate that DNA repair ingredients significantly prevent UV-induced immune suppression. [source] Predominant formation of heavily pigmented dermal melanocytomas resembling ,animal-type' melanomas in hepatocyte growth factor (C57BL/6 × C3H)F1 mice following neonatal UV irradiationJOURNAL OF CUTANEOUS PATHOLOGY, Issue 9 2007Scott R. Florell Background:, Transgenic mice expressing hepatocyte growth factor (HGF) develop cutaneous melanocytic tumors following neonatal UV exposure. Here, we examined the histologic spectrum of UV-induced melanocytic tumors in HGF mice on a pigmented (C57BL/6 × C3H/HeN)F1 background. Methods:, Neonatally irradiated (4000 J/m2) mice were monitored for 43 weeks, and 31/34 (91%) animals developed a total of 163 melanocytic tumors. Results:, Of 54 primary tumors analyzed, most (49/54, 91%) demonstrated exclusively dermal collections of epithelioid cells with voluminous densely pigmented cytoplasm. Seven of these also demonstrated a population of spindled cells with mitoses. Several (3/54, 6%) tumors exhibited a junctional component with melanocytes present in the epidermis. Staining with PEP8 confirmed the presence of interfollicular melanocytes at the dermal-epidermal junction in neonatal skin. Conclusions:, In contrast to HGF animals on an albino (FVB) background, HGF animals on the pigmented (C57BL/6 × C3H/HeN)F1 background do not develop classic radial growth phase melanoma but rather predominantly develop dermal melanocytomas resembling the ,animal-type' melanoma occasionally seen in humans. These results demonstrate the influence of genetic background on histologic pattern of UV-induced melanomas in mice. [source] Vitamin D and Bone Physiology: Demonstration of Vitamin D Deficiency in an Implant Osseointegration Rat ModelJOURNAL OF PROSTHODONTICS, Issue 6 2009James Kelly DDS Abstract Purpose: The patient population varies in nutritional deficiencies, which may confound the host response to biomaterials. The objective of this study was to evaluate the effect of a common deficiency of vitamin D on implant osseointegration in the rat model. Materials and Methods: Male Sprague-Dawley rats were maintained under the cessation of vitamin D intake and UV exposure. The serum levels of 1,25(OH)2D3, 25 OHD3, Ca, and P were determined. Miniature cylindrical Ti6Al4V implants (2-mm long, 1-mm diameter) were fabricated with double acid-etched (DAE) surface or modified DAE with discrete crystalline deposition (DCD) of hydroxyapatite nanoparticles. DAE and DCD implants were placed in the femurs of vitamin D-insufficient and control rats. After 14 days of healing, the femur-implant samples were subjected to implant push-in test and nondecalcified histology. The surfaces of recovered implant specimens after the push-in test were further evaluated by scanning electron microscopy (SEM). Results: The decreased serum level of 25 OHD3 demonstrated the establishment of vitamin D insufficiency in this model. The implant push-in test revealed that DAE and DCD implants in the vitamin D-insufficient group (15.94 ± 8.20 N, n = 7; 15.63 ± 3.96 N, n = 7, respectively) were significantly lower than those of the control group (24.99 ± 7.92 N, n = 7, p < 0.05; 37.48 ± 17.58 N, n = 7, p < 0.01, respectively). The transcortical bone-to-implant contact ratio (BIC) was also significantly decreased in the vitamin D-insufficient group. SEM analyses further suggested that the calcified tissues remaining next to the implant surface after push-in test appeared unusually fragmented. Conclusions: The effect of vitamin D insufficiency significantly impairing the establishment of Ti6Al4V implant osseointegration in vivo was unexpectedly profound. The outcome of Ti-based endosseous implants may be confounded by the increasing prevalence of vitamin D insufficiency in our patient population. [source] Interaction of Phytochemical-Quercetin with the Other Antioxidant, Ascorbic Acid and their Protective Effect in Tilapia after Ultraviolet IrradiationJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 5 2009Gustavo A. Rodriguez-Montes De Oca Semi-purified, casein-gelatin-based diets were prepared and supplemented with quercetin (Q) and/ or ascorbic acid (AA): control diet C,Q,(100 mg/kg AA), diet C ,Q+ (100 mg/kg AA + quercetin 10 g/kg), diet C +Q, (1000 mg/kg AA), and diet C +Q+ (1000 mg/kg AA + quercetin 10 g/kg). These diets were fed to tilapia for 19 wk and then fish were divided into controls and ultraviolet (UV) treatments. Fish were exposed to UV radiation. Control groups were protected with a MYLAR® polyester film and plexiglass. At week 20, the same fish were re-exposed to UV radiation. Control groups of fish were protected by a double layer of MYLAR® and the UV groups were exposed with no protection. Before UV exposure, 24 h after, and 7 d after the second treatment, fish liver and skin were dissected for Q and AA analyses. The proportion of oxidized ascorbate was significantly increased in fish from treatments C ,Q, and C ,Q+ . Q concentrations in fish after exposures were negligible in skin, whereas liver concentrations were significantly different among control (34 ± 10 ,g/g) and UV-irradiated fish (11 ± 6 ,g/g), respectively. The interaction between these two dietary antioxidants may change after chronic UV irradiation. [source] Stimulation of DNA repair and increased light output in response to UV irradiation in Escherichia coli expressing lux genesLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2007Kerry L. Cutter Abstract It has previously been suggested that the evolutionary drive of bacterial bioluminescence is a mechanism of DNA repair. By assessing the UV sensitivity of Escherichia coli, it is shown that the survival of UV-irradiated E. coli constitutively expressing luxABCDE in the dark is significantly better than either a strain with no lux gene expression or the same strain expressing only luciferase (luxAB) genes. This shows that UV resistance is dependent on light output, and not merely on luciferase production. Also, bacterial survival was found to be dependent on the conditions following UV irradiation, as bioluminescence-mediated repair was not as efficient as repair in visible light. Moreover, photon emission revealed a dose-dependent increase in light output per cell after UV exposure, suggesting that increased lux gene expression correlates with UV-induced DNA damage. This phenomenon has been previously documented in organisms where the lux genes are under their natural luxR regulation but has not previously been demonstrated under the regulation of a constitutive promoter. Copyright © 2007 John Wiley & Sons, Ltd. [source] Photoinduced Microphase Separation in Block Copolymers: Exploring Shape Incompatibility of Mesogenic Side GroupsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 11 2010Yi Zhao Abstract Photoinduced microphase separation in block copolymers (BCP) was achieved for the first time, using a rationally designed diblock copolymer composed of two side-chain liquid crystalline polymers (SCLCP). The miscibility of the two blocks was promoted by the miscibility between the two types of mesognic side groups, while upon UV exposure inducing the trans,cis isomerization of azobenzene mesogens on one SCLCP, the shape incompatibility of bent cis isomers with an ordered liquid crystalline phase drove the separation of the two blocks resulting in a microphase separated morphology. This result shows the perspective of using light to process and organize BCP morphology and related nanostructures in a lithography-free manner. [source] Kinetic Study and New Applications of UV Radiation CuringMACROMOLECULAR RAPID COMMUNICATIONS, Issue 18 2002Christian Decker Abstract Highly crosslinked polymers can be readily synthesized by photoinitiated polymerization of multifunctional monomers or functionalized polymers. The reaction can be followed in situ by real-time infrared (RT-IR) spectroscopy, a technique that records conversion versus time curves in photosensitive resins undergoing ultrafast polymerization upon UV exposure. For acrylate-based resins, UV-curing proceeds with long kinetic chains (7700 mol/radical) in spite of the high initiation rate. RT-IR spectroscopy proved very valuable in assessing the influence of various parameters, such as initiation efficiency, chemical structure of the telechelic oligomer, light intensity, inhibitory effect of oxygen, on polymerization kinetics. Interpenetrating polymer networks can be rapidly synthesized by means of UV irradiation of a mixture of difunctional acrylate and epoxy monomers in the presence of both radical and cationic-type photoinitiators. The same UV technology can be applied to crosslink solid polymers at ambient temperature, which bear different types of reactive groups (acrylate and vinyl double bonds, epoxy ring). UV radiation curing has been successfully used to produce within seconds weathering resistant protective coatings, high-resolution relief images, glass laminates and nanocomposites materials. Photoinitiated crosslinking polymerization. [source] Cyclooxygenase-2 deficiency increases epidermal apoptosis and impairs recovery following acute UVB exposureMOLECULAR CARCINOGENESIS, Issue 5 2007Jacqueline K. Akunda Abstract The cyclooxygenases, COX-1 and COX-2, are involved in cutaneous responses to both acute and chronic UV exposure. In the present study, wild-type (WT), COX-1,/, and COX-2,/, mice were used to determine the influence of the individual isoform on mouse skin responses to acute UVB treatment. Immunohistochemistry and Western analysis indicated that COX-2, and not COX-1, was induced by UVB (2.5 or 5.0 kJ/m2), but that COX-1 remained the major source of prostaglandin E2 production. UVB exposure significantly increased epidermal apoptosis in all genotypes compared to untreated mice. However, while the number of apoptotic cells in WT and COX-1,/, mice were about equal, the number of apoptotic cells was 2.5-fold greater in COX-2,/, mice. Apoptosis in WT and COX-2,/, mice peaked at 24 h post-exposure. The increased apoptosis and reduced proliferation in COX-2,/, mice resulted in about a 50% decrease in epidermal thickness at 24,48 h post-exposure compared to about a 50% increase in epidermal thickness in WT mice. UVB-induced cell replication, as measured by BrdU labeling, was reduced in COX-2,/, compared to WT mice at 24,96 h. However, by 96 h post-exposure, both WT and COX-2,/, mice showed epidermal hyperplasia. The data indicate that COX-2 induction initially protects against the acute sunburn effects of UVB, but that continuous induction of COX-2 may contribute to skin cancer in chronic UVB exposure. © 2007 Wiley-Liss, Inc. [source] Protective effect of vitamin E on ultraviolet B light,induced damage in keratinocytesMOLECULAR CARCINOGENESIS, Issue 3 2002Samar Maalouf Abstract Ultraviolet (UV) B radiation is the most common environmental factor in the pathogenesis of skin cancer. Exposure of human skin to UVB radiation leads to the depletion of cutaneous antioxidants, the activation of nuclear factor kappa B (NF-,B), and programmed cell death (apoptosis). Although antioxidant supplementation has been shown to prevent UVB-induced photooxidative damage, its effect on components of cell signaling pathways leading to gene expression has not been clearly established. In the present study, the effect of the antioxidant vitamin, ,-tocopherol (,-T), and its acetate analog, ,-tocopherol acetate (,-TAc), on UVB-induced damage in primary and neoplastic mouse keratinocytes was investigated. The ability of both vitamins to modulate UVB-induced apoptosis and activation of the transcription factor NF-,B were studied. Treatment of normal and neoplastic mouse epidermal keratinocytes (308 cells) with 30,60 mJ/cm2 UVB markedly decreased viable cell number and was accompanied by DNA fragmentation. When both vitamins were applied to cells at times before and after UVB radiation, a significant increase in the percentage of viable cells and concomitant decrease in the number of apoptotic cells was noted, with vitamin pretreatment providing a better protection than posttreatment. Simultaneous posttreatment of irradiated cells with ,-TAc abolished the cytotoxic effects of UVB and restored cell viability to control levels. In addition, simultaneous posttreatment of irradiated cells with ,-T reduced the number of apoptotic cells by half, indicating a synergistic effect of two such treatments compared with any single one. Flow cytometry analysis indicated that vitamin treatment suppressed both an increase in pre-G0 cells and a decrease in cycling cells by UVB exposure. In addition, NF-,B activation was detected 2 h after UV exposure and was maintained for up to 8 h. Pretreatment with vitamins significantly inhibited NF-,B activation at 4 and 8 h. These results indicate that vitamin E and its acetate analog can modulate the cellular response to UVB partly through their action on NF-,B activation. Thus, these antioxidant vitamins are potential drugs for the protection from or the reduction of UVB-associated epidermal damage. © 2002 Wiley-Liss, Inc. [source] UV Exposition During Typical Lifestyle Behavior in an Urban EnvironmentPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2010Alois W. Schmalwieser In this study the personal exposure to solar UV radiation in an urban environment was measured. Lifestyle in an urban environment is characterized by staying indoors during most of the day. Furthermore, the ambient UV radiation is mitigated by shadowing by buildings. The aim of the study was to find out activities which may contribute to UV-induced health risk in a low exposure environment. Exposure was measured during typical outdoor activities: shopping, walking, sitting in a sidewalk café, cycling, sightseeing and at an open-air pool (solar elevation: 10°,70°). Measurements were taken with an optoelectronic device which was fixed on the chest. Besides the UV Index we used the sun burn time (SBT) for risk assessments. Generalization of our results was made by calculating ratios of personal exposure to the ambient UV radiation. UV exposure was by far the highest when our study subject stayed at the swimming pool. The SBT was around 30 min for melano-compromised skin type. For all other activities, except shopping, the SBT range up to 1 h. With respect to photodamage we found that at high solar elevation (>45°) photoprotective measures should be applied for certain activities even within a city. [source] Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV RadiationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009Paul J. Janknegt Photoacclimation properties were investigated in two marine microalgae exposed to four ambient irradiance conditions: static photosynthetically active radiation (PAR: 400,700 nm), static PAR + UVR (280,700 nm), dynamic PAR and dynamic PAR + UVR. High light acclimated cultures of Thalassiosira weissflogii and Dunaliella tertiolecta were exposed outdoors for a maximum of 7 days. Dynamic irradiance was established by computer controlled vertical movement of 2 L bottles in a water filled basin. Immediate (<24 h), short-term (1,3 days) and long-term (4,7 days) photoacclimation was followed for antioxidants (superoxide dismutase, ascorbate peroxidase and glutathione cycling), growth and pigment pools. Changes in UVR sensitivity during photoacclimation were monitored by measuring UVR-induced inhibition of carbon assimilation under standardized UV conditions using an indoor solar simulator. Both species showed immediate antioxidant responses due to their transfer to the outdoor conditions. Furthermore, upon outdoor exposure, carbon assimilation and growth rates were reduced in both species compared with initial conditions; however, these effects were most pronounced in D. tertiolecta. Outdoor UV exposure did not alter antioxidant levels when compared with PAR-only controls in both species. In contrast, growth was significantly affected in the static UVR cultures, concurrent with significantly enhanced UVR resistance. We conclude that antioxidants play a minor role in the reinforcement of natural UVR resistance in T. weissflogii and D. tertiolecta. [source] Zoospores of Three Arctic Laminariales Under Different UV Radiation and Temperature Conditions: Exceptional Spectral Absorbance Properties and Lack of Phlorotannin InductionPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Ruth Müller Phlorotannins have often been considered to act as UV-protective compounds in zoospores of brown algae. However, only the absorption characteristics of zoospores under UV exposure have been determined and no data are available on the actual content of phlorotannins or on temperature,UV interactions. Therefore, we determined the absorbance spectra and the phlorotannin contents in zoospore suspensions of three Arctic species (Saccharina latissima, Laminaria digitata, Alaria esculenta), and in the media surrounding zoospores after exposure to different radiation (400,700, 320,700, 295,700 nm) and temperature (2,18°C) conditions for 8 h. Absorption typical of phlorotannins with a maximum at 276 nm was monitored in zoospore suspensions as well as in the media surrounding zoospores, but the results depended strongly on radiation treatments and on zoospore densities. Surprisingly, the content of UV-absorbing phlorotannins subsequent to different exposures did not change in any of the three species. The observed exceptional absorption properties could, therefore, not be related to phlorotannin contents. These findings are discussed in light of a strong phlorotannin investment from sporophytes during spore release and a minor UV-protective role of phlorotannins for zoospores of Arctic kelp species. [source] UV-induced Immunosuppression in the Balance,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2008Frank R. De Gruijl Around 1980, experiments with hairless mice showed us that UV-induced actinic keratoses (AK) and ensuing skin carcinomas did not arise independently: the rate of occurrence in one skin area was increased considerably if AKs had already been induced separately in another distant skin area, i.e. a systemic effect. The ground laying work of Margaret Kripke in the 1970s provided a fitting explanation: UV-induced immunosuppression and tolerance toward the UV-induced tumors. From Kripke's work a new discipline arose: "Photoimmunology." Enormous strides were made in exploring and expanding the effects from UV carcinogenesis to infectious diseases, and in elucidating the mechanisms involved. Stemming from concerns about a depletion of the ozone layer and the general impact of ambient UV radiation, the groups I worked in and closely collaborated with explored the anticipated adverse effects of UV-induced immunosuppression on healthy individuals. An important turning point was brought about in 1992 when the group of Kevin Cooper reported that immunosuppression could be induced by UV exposure in virtually all human subjects tested, suggesting that this is a normal and sound physiological reaction to UV exposure. This reaction could actually protect us from illicit immune responses against our UV-exposed skin, such as observed in idiopathic polymorphic light eruption. This premise has fruitfully rekindled the research on this common "sun allergy," affecting to widely varying degrees about one in five Europeans with indoor professions. [source] Protective Effect of Sanguinarine on Ultraviolet B-mediated Damages in SKH-1 Hairless Mouse Skin: Implications for Prevention of Skin CancerPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Haseeb Ahsan Excessive exposure of solar ultraviolet (UV) radiation, particularly its UVB component (280,320 nm), to human skin is the major cause of skin cancers. UV exposure also leads to the development of precancerous conditions such as actinic keratosis and elicits a variety of other adverse effects such as sunburn, inflammation, hyperplasia, immunosuppression and skin aging. Therefore, there is a need to intensify our efforts towards the development of novel mechanism-based approaches/agents for the protection of UVB-mediated damages. Chemoprevention is being investigated as a potential approach for the management of UV damages including skin cancer. We have earlier shown that sanguinarine, a benzophenanthridine alkaloid, inhibits UVB exposure-mediated damages in HaCaT keratinocytes. In this study, to determine the relevance of our in vitro findings to in vivo situations, we assessed the effects of sanguinarine on UVB-mediated damages in SKH-1 hairless mice. Our data demonstrated that a topical application of sanguinarine (5 ,mol 0.3 mL,1 ethanol per mouse), either as a pretreatment (30 min prior to UVB) or posttreatment (5 min after UVB), resulted in a significant decrease in UVB-mediated increases in skin edema, skin hyperplasia and infiltration of leukocytes. Further, sanguinarine treatments (pre and post) also resulted in a significant decrease in UVB mediated (1) generation of H2O2 and (2) increases in the protein levels of markers of tumor promotion/proliferation viz. ornithine decarboxylase (ODC), proliferating cell nuclear antigen (PCNA) and Kiel antigen-67. Based on this data, we suggest that sanguinarine could be developed as an agent for the management of conditions elicited by UV exposure including skin cancer. However, further detailed studies are needed to support this suggestion. [source] Detection of Modified Tyrosines as an Inflammation Marker in a Photo-aged Skin ModelPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2007Yukiko Ishitsuka Reactive nitrogen species, produced during the process of inflammation induced by various factors including UV radiation, modify amino acids in crucial proteins. It is assumed that skin tissue is more likely to be modified, as it is located at the outer layer of a body that is exposed to UV radiation on a daily basis. To investigate the influence of the modified tyrosine on UV-exposed skin, we detected the nitrotyrosine or halogenated tyrosine and dityrosine in photo-aged model mice. The back skin of mice was exposed to a dose of 10 J cm,2 day,1 every day for 15 weeks. Samples exhibiting typical symptoms of photo aging were provided to the immunofluorescence study. The quantification of modified proteins was accomplished through a chemical analytical method known as HPLC-tandem mass spectrometry. Analysis of the irradiated skin samples showed that all modified tyrosine except nitrotyrosine demonstrated statistically significant increases. The molecular weights of major modified proteins, confirmed as 25,50 kDa, were measured using Western blot analysis with an anti-nitrotyrosine antibody. Furthermore, the immunofluorescence study verified that the localization of myeloperoxidase conformed to that of nitrotyrosine. This result suggests that the modified tyrosine was produced during the process of inflammation by UV irradiation. In this study, we used a low dose of UV irradiation to which we are exposed in daily life. Our results suggest that UV exposure in daily life may induce the production of modified tyrosines and skin aging. [source] | ||||||||||||||||||||||||||||||||||