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The Benefits of UV Light Read and discuss all the great news about UV light and Vitamin D. |
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05-08-2008, 08:13 PM | #1 (permalink) |
Join Date: Feb 10 2005
Posts: 8,304
Rep Power: 35 | P53's -- Repeated UV irradiation protects against UV induced DNA damage. Dermatol. 2008 Mar 23; : 18363705 (P,S,E,B,D) Cyclobutane pyrimidine dimer formation and p53 production in human skin after repeated UV irradiation. [My paper] Yuji Yamaguchi, Sergio G Coelho, Barbara Z Zmudzka, Kaoruko Takahashi, Janusz Z Beer, Vincent J Hearing, Sharon A Miller Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. Substantial differences in DNA damage caused by a single UV irradiation were found in our previous study on skin with different levels of constitutive pigmentation. In this study, we assessed whether facultative pigmentation induced by repeated UV irradiation is photoprotective. Three sites on the backs of 21 healthy subjects with type II-III skin were irradiated at 100-600 J/m(2) every 2-7 days over a 4- to 5-week period. The three sites received different cumulative doses of UV (1900, 2900 or 4200 J/m(2)) and were biopsied 1 day after the last irradiation. Biomarkers examined included pigment content assessed by Fontana-Masson staining, melanocyte function by expression of melanocyte-specific markers, DNA damage as cyclobutane pyrimidine dimers (CPD), nuclear accumulation of p53, apoptosis determined by TUNEL assay, and levels of p21 and Ser46-phosphorylated p53. Increases in melanocyte function and density, and in levels of apoptosis were similar among the 3 study sites irradiated with different cumulative UV doses. Levels of CPD decreased while the number of p53-positive cells increased as the cumulative dose of UV increased. These results suggest that pigmentation induced in skin by repeated UV irradiation protects against subsequent UV-induced DNA damage but not as effectively as constitutive pigmentation. SOURCE LINK: http://lib.bioinfo.pl/pmid:18363705
__________________ "under exposure to UV rays is as dangerous as overexposure....this is D life" eileen |
05-08-2008, 08:16 PM | #2 (permalink) |
Join Date: Feb 10 2005
Posts: 8,304
Rep Power: 35 | Re: P53's -- Repeated UV irradiation protects against UV induced DNA damage. Don shouldn't this add more validity to Dr. Fisher's findings?
__________________ "under exposure to UV rays is as dangerous as overexposure....this is D life" eileen |
05-08-2008, 08:26 PM | #4 (permalink) |
Join Date: Feb 10 2005
Posts: 8,304
Rep Power: 35 | Re: P53's -- Repeated UV irradiation protects against UV induced DNA damage. I interpret it as more good news based on scientific studies. I'm sure Don will help us out with it. :)
__________________ "under exposure to UV rays is as dangerous as overexposure....this is D life" eileen |
05-08-2008, 09:52 PM | #5 (permalink) |
Join Date: Feb 25 2000 Location: Tucson, AZ
Posts: 1,643
Rep Power: 26 | Re: P53's -- Repeated UV irradiation protects against UV induced DNA damage. The paper is well worth getting for your library. It is "good news" because it shows what salon owners already know--that the development of facultative pigmentation, a.k.a., a tan, via controlled ultraviolet radiation exposure provides protection in direct proportion to the level of tan. In this study they compared three "protocols" / Protocol A had a cumulative dose of 1900 J/m^2 (19 SED); Protocol B had a cumulative dose of 2900 J/m^2 (29 SED); and Protocol C had a cumulative dose of 4200 J/m^2 (42 SED). [Note: These doses were calculated using the CIE AS, not the FDA EAS.] I am meeting with some of the authors in Washington, DC later this month and, after I get some answers to some questions I have regarding the data in this paper, I will have more to say about this important paper. In the meantime, "be comforted" by the fact that this is a good "3rd party reference" showing that a tan is photoprotective (even if the dermatolgists don't/won't/can't/are too stupid to agree). |
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