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Query: UMLS:C0849640 (skin damage)
 1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

While assessing the protective effect of broad-spectrum sunscreens against chronic UVA radiation, we observed a paradoxical worsening of skin damage with one product. To further examine this finding, five proprietory broad-spectrum sunscreens were applied to albino hairless mice irradiated thrice weekly for 32 weeks with a UVASUN lamp (> 340 nm). Appropriate age-matched controls were included. After approximately 12 weeks, two sunscreens induced a marked dermatitis. Biopsies showed damage greatly exceeding that found in UVA-irradiated, unprotected controls. Histologically, elastic fibers were hyperplastic, coalescing into elastotic clumps. Glycosaminoglycans also increased. Collagen damage was notable since UVA alone does not induce a histologic change. Electron microscopy confirmed these findings. Two other sunscreens provided nearly complete protection. Against chronic UVB radiation, the two UVA photoirritating sunscreens provided substantial protection. Since the UVA sunfilter, oxybenzone, was the same in all sunscreens, we postulate that an irritating component of the vehicle was responsible for the UVA-induced photoirritation. The fifth sunscreen produced severe damage with UVB and UVA.
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PMID:Photoirritation: a new photobiologic phenomenon induced by long wavelength UVA radiation in hairless mice treated with broad-spectrum sunscreens. 765 81

In this ultrastructural study, albino hairless mice were irradiated with long-wavelength ultraviolet (UVA) (340-400 nm) thrice weekly for 32 weeks for a cumulative dose of 8000 J/cm2. Biopsies were taken from these mice, from age-matched unirradiated controls, and from mice irradiated with UVB for 20-30 weeks with a cumulative dose of approximately 6-9 J/cm2. The most striking UVA-induced changes were 1) elastic fiber hyperplasia without evidence of fiber disintegration, 2) a large increase in randomly deposited microfibrils; 3) massive duplication of vascular basement membrane; 4) extensive endothelial cell damage; and 5) collagen fibers with smaller diameters but without apparent damage. By contrast, after UVB, the hyperplastic elastic fibers frequently appeared to be degraded. Microfibrils were only moderately increased and remained in an organized array. Also, unlike with UVA, the epidermal basement membrane was duplicated whereas that of the vessels was mainly spared. Collagen fibers showed evidence of dissolution. Thus, ultrastructural features provide further evidence that skin damage induced by UVA can be dissimilar to that induced by UVB.
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PMID:UVA-induced ultrastructural changes in hairless mouse skin: a comparison to UVB-induced damage. 842 42

Accidental radiation exposures or radiation therapy can cause internal and external damage including radiodermatitis. Even though radiodermatitis is one of the dose limiting factors in radiotherapy, the immunological nature of it is not yet been clearly understood. In this study, we have examined the alteration in immune cell population during the radiodermatitis process. A radiodermatitis model was established in HR-1 mice by locally exposing a posterior dorsal region to 10 Gy X-ray/day for 4 consecutive days. Collagen accumulation, redness, erythema, and dry desquamation of the skin were detected after X-irradiation. The size and total cell number of the spleen decreased immediately after X-irradiation, compared to those of the sham-irradiated mice, and recovered to the normal levels two weeks later. Reduction and recovery of the bone marrow cell population preceded a similar change of the spleen cell population. The proportion of CD4+ T cell increased, while the proportion of CD8+ T cell decreased ahead of the obvious skin damage, in both lymph node and spleen of the irradiated mice. Interestingly, the proportion of splenic monocytes/macrophages was expanded gradually at a similar kinetics with the aggravation of the radiodermatitis. The infiltration of the CD11b+ monocyte/macrophage to the X-irradiated skin also coincided with the development of radiodermatitis. These altered proportions of immune cells may play important roles in radiodermatitis.
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PMID:Altered immune cell proportions in the radiodermatitis induced hairless mice-1 (HR-1). 1657 14

Collagen sheets were used in a unique evaluation method to examine skin damage caused by ultraviolet (UV) light of short wavelength during a season of the Antarctic ozone hole. The collagen sheets were exposed outdoors for 25 and 50 d, in the spring when the ozone hole was formed and in the ozone-hole-free autumn. Extracts from the exposed collagen sheets were analyzed for total protein and terminal amino acid concentrations as an index of collagen fragmentation. The results show that the amount of extractable collagen and terminal amino acid concentration in the spring exposure were approximately double and five times higher, respectively, when compared with those in the autumn exposure. During the ozone hole occurrence, the terminal amino acid concentration of the extracted collagen was about five times higher when exposure lasted 50 d from mid-September to the end of October compared to when exposure lasted 25 d from mid-September to early October. This result could be attributed to a limited amount of short-wavelength UV radiation reaching the ground surface as a result of the low height of the sun in September, when the ozone hole occurred. In fact, UV radiation measurements taken at Syowa Station indicate that short-wavelength UV radiation in the range 290-295 nm was not detected until approximately 1-2 months after the beginning of the ozone hole occurrence.
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PMID:Measurement of solar UV radiation in Antarctica with collagen sheets. 2241 56

The efficacy of wheat extract oil (WEO), standardized to glucosylceramides, for protecting against ultraviolet B (UVB)-induced damage of skin barrier function was assessed using the SHK-1 hairless mouse model and two human skin cell lines, namely, CCD-986sk and HeCaT. The ability of repeated oral administration of 30, 60, and 120 mg of WEO/kg/day for 12 weeks to prevent skin damage of SKH-1 hairless mice induced by UVB irradiation was evaluated. The results demonstrated that UVB-induced water evaporation (transepidermal water loss, TEWL) was significantly decreased by WEO. Similarly, UVB-induced losses in moisture and skin elasticity were improved by WEO supplementation. WEO attenuated the tissue procollagen type I, hyaluronic acid (HA), and ceramide reductions induced by UVB treatment as well. Collagen concentrations in skin tissue were increased in the WEO-treated mice, while UVB-induced epidermal thickening was reduced. In vitro studies using HeCaT human keratinocytes confirmed increased HA and collagen synthesis in response to WEO treatment. This may occur via WEO suppression of matrix metallopeptidase-1 (MMP-1), since its induction by UVB treatment was diminished in treated CCD-986sk cells. Oral administration of WEO improves skin barrier function in UVB-irradiated mice by attenuating damage typically observed in photoaging. This research further clarifies the clinical benefits previously observed by dietary WEO consumption.
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PMID:Wheat Extract Oil (WEO) Attenuates UVB-Induced Photoaging via Collagen Synthesis in Human Keratinocytes and Hairless Mice. 3197 27

A number of studies have demonstrated that marine carbohydrates display anti-oxidant, anti-melanogenic, and anti-aging activities in the skin. Laminarin (LA), a low-molecular-weight polysaccharide, is found in brown algae. The benefits of LA in ultraviolet B (UVB) induced photodamage of the skin have not been reported. The aim of this study was to investigate the effects of pre-treated LA on histopathological changes and oxidative damage in mouse dorsal skin on day 5, following repeated UVB exposure. Histopathology, Western blot analysis and immunohistochemical studies showed that epidermal thickness in the UVB group was significantly increased; however, the thickness in the UVB group treated with LA (LA/UVB group) was less compared with that of the UVB group. Collagen fibers in the dermis of the UVB group were significantly decreased and destroyed, whereas, in the LA/UVB group, the density of collagen fibers was significantly increased compared with that of the UVB group. Oxidative stress due to superoxide anion production measured via dihydroethidium fluorescence staining was dramatically increased in the UVB group, whereas in the LA/UVB group, the oxidative stress was significantly decreased. Expressions of SOD1, glutathione peroxidase and catalase were markedly reduced in the UVB group, whereas in the LA/UVB group, they were significantly higher along with SOD2 than in the control group. Taken together, our results indicate that LA pretreatment prevents or attenuates skin damage, by decreasing oxidative stress and increasing antioxidant enzymes in mouse dorsal skin.
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PMID:Laminarin Attenuates Ultraviolet-Induced Skin Damage by Reducing Superoxide Anion Levels and Increasing Endogenous Antioxidants in the Dorsal Skin of Mice. 3262 14