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

Both healthy female rats of the Wistar strain (VELAZ breed) and those irradiated with a single whole-body dose of 5 Gy gamma radiation (60Co) were exposed on the back to non-contact infrared radiation (IR lamp with an output of 250 W: skin surface temperature at a distance of 3 cm from the crown of the lamp = magnitude of 110 +/- 2 degrees C) for time periods of 40 s, 20 s, 10 s (healthy) and 20 s (irradiated animals). The surface range of thermic damage to the skin was determined using planimetry and measuring the length and the width of the burn with the respect to an immediate contraction. The mean values of an immediate retraction of the burnt skin and the interval of reliability of their estimate (p < 0.05) were significantly lower in 10 s exposure and in whole-body irradiation rats after 20 s (magnitude of 5.6 +/- 2.5 % ... 10 s; magnitude of 12.56 +/- 3.86 % ... in irradiated animals) than the retraction of non-irradiated rats (magnitude of 15.98 +/- 4.86 % ... in 20 s; magnitude of 31.88 +/- 7.34 % ... in 40 s). For a period of 90 min after burning, no substantial changes were found in rectal temperature (33.4 degrees C to 35.4 degrees C). Before a thermic trauma the drop in the temperature from the skin surface reached cca 2 degrees C subcutaneously, after burning in the centre of the burn about 17 degrees C and 9 degrees C in other exposures using the IR lamp. The mean time of burn healing in non-irradiated animals was the shortest in 10 s exposure (magnitude of 17 +/- 2 days), the damage in the centre reaching II b degree while after 40 s exposure the burn reached IV degree and also the longest healing time (magnitude of 60 +/- 4 days). After 20 s exposure, the mean healing times in irradiated rats were longer (magnitude of 39 +/- 3) days and so the skin damage (III to IV degree) as compared with non-irradiated animals where the mean healing time amounted to (34 +/- 4) days, the burns being of III degree.
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PMID:[Non-contact experimental burns in rats]. 143 89

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

The major side effect of photodynamic therapy (PDT) using Photofrin is enhanced skin sensitivity for sunlight, which persists for 3-8 weeks after injection. Formation of singlet oxygen and radicals is believed to be involved in the basic mechanism of inducing skin damage. Reducing this side effect would make PDT more widely acceptable, particularly for palliative use. Hairless dorsal skin patches of mice, injected with 10 mg kg-1 photofrin intraperitoneally (i.p.) 24 h before illumination, were used to evaluate the effect of increasing light doses. The light was obtained from a halogen lamp and transmitted via a fiber optic to illuminate a field of 2.5 cm2. After establishing a dose-response relationship for single or fractionated light dose illumination of the skin, drugs known to scavenge radicals, quench singlet oxygen or interfere with histamine release were tested for their protective effect. N-acetyl-cysteine (NAC), a radical scavenger, administered i.p. (1000 and 2000 mg kg-1) 1 h before illumination produced a significant decrease in skin damage at light doses > 50 J cm-2 (protection factor of 1.3-1.8). When NAC was administered in a dose of 500 mg kg-1, no protection was observed. Fractionated illumination experiments in combination with multiple injections of NAC (1000 mg kg-1) also failed to show any protection. The addition of Ranitidine, a histamine blocking agent (25-100 mg kg-1), given prior to illumination, resulted in a limited protection at higher light doses. From this study we conclude that NAC could be of value in amelioration of the photosensitivity in patients treated with PDT.
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PMID:Partial protection of photodynamic-induced skin reactions in mice by N-acetylcysteine: a preclinical study. 802 87

UV radiation is known to cause acute and chronic eye and skin damage. The present case report describes a 90 min accidental exposure to UV-C radiation of 26 medical school students. Germicidal lamps were lit due to a malfunctioning of the timer system. Several hours after irradiation exposure, all subjects reported the onset of ocular symptoms, subsequently diagnosed as photokeratitis, and skin damage to the face, scalp and neck. While the ocular symptoms lasted 2-4 days, the sunburn-like condition produced significant erythema followed by deep skin exfoliation. The irradiation was calculated to be approximately 700 mJ cm(-2) absorbed energy, whereas the actual radiation emitted by the lamps was 0.14 mW cm(-2) (the radiometric measurements confirmed these calculi, because the effective irradiance measured from the height of the autopsy table to about 1 m under the UV-C lamp varied from 0.05 to 0.25 mW cm(-2)) but, more likely, the effective irradiance, according to skin phototype and symptoms, was between 50 and 100 mJ cm(-2). The ocular and skin effects produced by such a high irradiation (largely higher than that accepted by the American Conference of Governmental Industrial Hygienists [ACGIH] threshold limit values [TLVs]) appeared reversible in a relatively short time.
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PMID:Unusual high exposure to ultraviolet-C radiation. 1720 32

We have previously shown that 207-nm ultraviolet (UV) light has similar antimicrobial properties as typical germicidal UV light (254 nm), but without inducing mammalian skin damage. The biophysical rationale is based on the limited penetration distance of 207-nm light in biological samples (e.g. stratum corneum) compared with that of 254-nm light. Here we extended our previous studies to 222-nm light and tested the hypothesis that there exists a narrow wavelength window in the far-UVC region, from around 200-222 nm, which is significantly harmful to bacteria, but without damaging cells in tissues. We used a krypton-chlorine (Kr-Cl) excimer lamp that produces 222-nm UV light with a bandpass filter to remove the lower- and higher-wavelength components. Relative to respective controls, we measured: 1. in vitro killing of methicillin-resistant Staphylococcus aureus (MRSA) as a function of UV fluence; 2. yields of the main UV-associated premutagenic DNA lesions (cyclobutane pyrimidine dimers and 6-4 photoproducts) in a 3D human skin tissue model in vitro; 3. eight cellular and molecular skin damage endpoints in exposed hairless mice in vivo. Comparisons were made with results from a conventional 254-nm UV germicidal lamp used as positive control. We found that 222-nm light kills MRSA efficiently but, unlike conventional germicidal UV lamps (254 nm), it produces almost no premutagenic UV-associated DNA lesions in a 3D human skin model and it is not cytotoxic to exposed mammalian skin. As predicted by biophysical considerations and in agreement with our previous findings, far-UVC light in the range of 200-222 nm kills bacteria efficiently regardless of their drug-resistant proficiency, but without the skin damaging effects associated with conventional germicidal UV exposure.
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PMID:Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light. 2822 54