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Ultraviolet light
About: Ultraviolet light is a research topic. Over the lifetime, 49494 publications have been published within this topic receiving 843151 citations.
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TL;DR: The oncoproteins E6 and E7 from beta HPV38 significantly contribute to SCC development in the skin rendering keratinocytes more susceptible to UV-induced carcinogenesis.
Abstract: Cutaneous beta human papillomavirus (HPV) types appear to be involved in the development of non-melanoma skin cancer (NMSC); however, it is not entirely clear whether they play a direct role. We have previously shown that E6 and E7 oncoproteins from the beta HPV type 38 display transforming activities in several experimental models. To evaluate the possible contribution of HPV38 in a proliferative tissue compartment during carcinogenesis, we generated a new transgenic mouse model (Tg) where HPV38 E6 and E7 are expressed in the undifferentiated basal layer of epithelia under the control of the Keratin 14 (K14) promoter. Viral oncogene expression led to increased cellular proliferation in the epidermis of the Tg animals in comparison to the wild-type littermates. Although no spontaneous formation of tumours was observed during the lifespan of the K14 HPV38 E6/E7-Tg mice, they were highly susceptible to 7,12-dimethylbenz(a)anthracene (DMBA)/12-0-tetradecanoylphorbol-13-acetate (TPA) two-stage chemical carcinogenesis. In addition, when animals were exposed to ultraviolet light (UV) irradiation, we observed that accumulation of p21WAF1 and cell-cycle arrest were significantly alleviated in the skin of Tg mice as compared to wild-type controls. Most importantly, chronic UV irradiation of Tg mice induced the development of actinic keratosis-like lesions, which are considered in humans as precursors of squamous cell carcinomas (SCC), and subsequently of SCC in a significant proportion of the animals. In contrast, wild-type animals subjected to identical treatments did not develop any type of skin lesions. Thus, the oncoproteins E6 and E7 from beta HPV38 significantly contribute to SCC development in the skin rendering keratinocytes more susceptible to UV-induced carcinogenesis.
138 citations
TL;DR: A continuous post-irradiation treatment with non-toxic levels of caffeine enhanced the lethal effect of UV light in both xeroderma pigmentosum variant cell strains but not in cells from normal individuals.
Abstract: • A uniform response to UV of four normal cell strains was demonstrated. One excision-proficient xeroderma pigmentosum variant strain (XP7TA) had a wild-type UV response but a second (XP30RO) was more sensitive. An excision-deficient xeroderma pigmentosum strain XP4LO was substantially more sensitive than wild-type cell strains. • A continuous post-irradiation treatment with non-toxic levels of caffeine enhanced the lethal effect of UV light in both xeroderma pigmentosum variant cell strains but not in cells from normal individuals. There was no detectable effect on cells from a xeroderma pigmentosum individual from complementation group A. These results correlate well with observations on the influence of caffeine on post-replication repair in the three classes of cells.
138 citations
TL;DR: In this paper, a Pechini so-gel process was used to produce CaIn2O4:Eu3+ phosphors, which were then used for X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL), cathodolumine (CL) spectra as well as lifetimes were utilized to characterize the samples.
Abstract: CaIn2O4:Eu3+ phosphors were prepared by a Pechini so-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL), cathodoluminescence (CL) spectra as well as lifetimes were utilized to characterize the samples. The XRD results reveal that the samples begin to crystallize at 800 degrees C, and the crystallinity increases upon raising the annealing temperature. The FE-SEM images indicate that the CaIn2O4:Eu3+ samples consist of fine and spherical grains with size around 200-400 nm. Under the excitation of ultraviolet light and low-voltage electron beams, the CaIn2O4:Eu3+ phosphors show the characteristic emissions of Eu3+ ((DJ-7FJ ')-D-5 J, J ' = 0, 1, 2, 3 transitions). The luminescence color can be tuned from white to orange to red by adjusting the doping concentration of EU3+. The corresponding luminescence mechanisms have been proposed.
138 citations
TL;DR: It is concluded that an excision-repair mechanism operates on nuclear but not mitochondrial DNA in repair-proficient yeast, and that the rad1-2 mutant is defective in this process.
138 citations
TL;DR: In this paper, the authors demonstrate the unique potential and the versatility of the PEEM approach, and review the current status with a certain emphasis on experiments with soft x-ray excitation.
Abstract: The imaging of surfaces by means of photoexcitation electron emission microscopy (PEEM) has recently received considerable interest. This is mainly due to the extended use and availability of brilliant synchrotron radiation in the soft x-ray regime which generally facilitates studies with surface specificity and chemical selectivity. The most popular application of the x-ray PEEM (XPEEM) technique concerns studies of magnetic systems and phenomena. By exploiting the high degree of circular or linear polarization of the synchrotron light, the magnetic microstructure in both ferromagnets and antiferromagnets can be visualized. In this contribution we demonstrate the unique potential and the versatility of the PEEM approach, and review the current status with a certain emphasis on experiments with soft x-ray excitation. In some cases, the high-energy excitation studies can be complemented by laboratory experiments employing threshold photoemission with ultraviolet light (UV-PEEM). Current limitations and future developments and perspectives of the PEEM technique applied to magnetic systems are discussed.
138 citations