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Results for “RADIODERMATITIS”

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At least 613 records · Page 34Linked to original sources
PubMed1977

Effects of topically-applied olive oil on the response of hamster skin to single or multiple doses of 230kV X-rays.

The effects of topically-applied olive oil on the response of hamster skin to single or multiple doses of X-rays has been studied. The olive oil was applied either 15 min or 1 hour before the radiation exposures. The treatment did not alter the temporal pattern of development and recovery from the radiation injury. For single exposers, olive oil did not alter the 1- to 30-day average skin response. However, when it was administered at each treatment when three radiation fractions were given over a 4-day interval (3 fractions/4 days), a significant increase in the amount of dose recovered was found compared with control irradiated animals. For controls, the average amount of dose recovered per fractionation interval, (Dn-D1)/(n-1), was about 505 rad. For animals treated with olive oil 15 min before irradiation, it was about 720 rad; and for those treated 1 hour before irradiation, it was 782 rad. The data indicate a definite radioprotective effect of topical administration of olive oil, but at present the mechanism is not known.

Administration, Topical↗
PubMed1983

The relationship between 'early' and 'late' radiation-induced skin reactions as seen in two strains of mice that differ in radiosensitivity.

The acute skin reaction and time-course of skin contraction following graded single doses of X-rays were studied in CBA and C57B1 mice, in order to elucidate the relationship between 'early' and 'late' skin damage in strains that are known to differ in radiosensitivity. A dose-dependent acute reaction and rapid skin contraction was noted 0-50 days after irradiation in both strains, and both parameters of response were greatest in the C57B1 mice. Following this initial shrinkage there was a slight relaxation, which was again more evident in the C57s. A gradual, continuous, dose-independent contraction from 50-466 days was evident in CBA mice, whereas in C57s there was no evidence of late shrinkage. Histological examination at 466 days post-irradiation revealed a greater epidermal hyperplasia in CBA than in C57 mice. Comparison of these results with data on acute intestinal damage and early and late lung damage shows no general relationship between the incidence of early and late radiation damage in these two strains of mice.

Acute Disease↗
PubMed1991

Protection of pig epidermis against radiation-induced damage by the infusion of BW12C.

BW12C, which was developed as an agent for the treatment of sickle cell anaemia, increases the binding of oxygen to haemoglobin and hence reduces the availability of oxygen to tissues. Due to these changes in oxygen availability BW12C could act as a protector against radiation-induced injury to normal tissues. In this study the potential value of BW12C, as a radioprotector, was studied in the irradiated epidermis of the pig. The infusion of BW12C caused an instant left shift of the oxygen dissociation curve, an effect that lasted for approximately 1.5 h. This left shift in the oxygen dissociation curves increased with increasing dose of the drug. There appeared to be no long-term systemic effects produced by doses of 20-100 mg/kg of BW12C. In the first 90 min after the infusion of BW12C skin fields were irradiated with single doses of beta-rays from strontium-90 plaques. The incidence of moist desquamation was used as an endpoint for assessing the severity of the radiation response. With animals breathing approximately 70% oxygen in the anaesthetic gas mixture, the ED50 values for moist desquamation were 30-31 Gy after a dose of 30 and 50 mg/kg, and 37-38 Gy for 75 and 100 mg/kg doses of BW12C. These ED50 values were significantly higher than the value of 27.3 Gy for radiation alone. This indicated dose modification factors (DMF) with mean values of approximately 1.13 and approximately 1.40 for irradiation following the infusion of low (30-50 mg/kg) and high (75-100 mg/kg) doses of the drug, respectively. With the animals breathing air (approximately 21% of oxygen) in the 2% halothane anaesthesia gas mixture, irradiation in the presence of 30 and 50 mg/kg of BW12C resulted in ED50 values of approximately 39 Gy for moist desquamation, which was significantly higher than the value of 31.2 Gy for radiation alone. Surprisingly, a higher dose of 75 mg/kg of BW12C resulted in a lower ED50 value for moist desquamation of 34.38 Gy. Irradiation in the presence of a dose of 100 mg/kg of BW12C produced an ED50 value which was not significantly different from that for radiation alone. In the situation where animals were breathing air (approximately 21% oxygen) during irradiation a DMF of 1.14 was obtained for irradiation alone, when the results were compared with those for irradiation alone with approximately 70% oxygen in the anaesthetic gas mixture.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

Electrohypersensitivity: state-of-the-art of a functional impairment.

Recently, a new category of persons, claiming to suffer from exposure to electromagnetic fields, has been described in the literature. In Sweden, electrohypersensitivity (EHS) is an officially fully recognized functional impairment (i.e., it is not regarded as a disease). Survey studies show that somewhere between 230,000-290,000 Swedish men and women report a variety of symptoms when being in contact with electromagnetic field (EMF) sources. The aim of our studies has been to investigate possible alterations, in the cellular and neuronal systems of these person' skin. As controls, age- and sex-matched persons, without any subjective or clinical symptoms or dermatological history, served. Immunohistochemistry using antisera to the previously characterized marker substances of interest has been utilized. In summary, it is evident from our preliminary data that various alterations are present in the electrohypersensitive person' skin. In view of recent epidemiological studies, pointing to a correlation between long-term exposure from power-frequent magnetic fields or microwaves and cancer, our data ought to be taken seriously and further analyzed.

Animals↗
PubMed2006

A double-blind, vehicle-controlled clinical study to evaluate the efficacy of MAS065D (XClair), a hyaluronic acid-based formulation, in the management of radiation-induced dermatitis.

This study was designed to assess the efficacy and tolerability of MAS065D (Xclair) compared to a vehicle control in the management of radiation dermatitis in patients receiving radiotherapy for breast cancer. Twenty patients were randomized blindly to use the two study substances, three times daily, on separate sections of irradiated skin throughout the duration of radiotherapy and for two weeks afterwards. Patients were monitored before therapy, weekly during therapy, and for 2 weeks after radiotherapy was completed. Skin appearance according to National Cancer Institute (NCI) toxicity criteria, erythema rating, transepidermal water loss (TEWL), skin hydration, patients' view of itch, pain, acceptance, and view of each cream and adverse events, were monitored; at the final visit patients and investigators expressed their preference for one of the creams. MAS065D showed statistically significant superiority in the outcomes of NCI grading for radiation dermatitis and erythema. Patients' and investigators' preferences for one of the study substances were statistically in favor of MAS065D. Very few patients recorded nonzero itch and pain scales, so no significant differences emerged between the two groups. It was concluded that MAS065D can provide an effective option for managing radiation dermatitis although further studies are needed to assess its effect on pain and itch.

Breast Neoplasms↗
PubMed2004

The effect of optimization on surface dose in intensity modulated radiotherapy (IMRT).

Although IMRT has been shown clinically to increase skin doses for some patients, it has also been shown that intensity modulated delivery does not, of itself, increase skin doses. The reason for this apparent difference is that inverse planning can result in solutions that give high fluence to tangential beam segments near the skin surface, in an attempt to counter the build-up region. In cases where the clinical target volume (CTV) stops short of the skin surface, but the planning target volume (PTV) does not, there is no clinical reason to treat the skin. The CTV-PTV margin exists purely to ensure that fields are large enough to allow for geometrical uncertainties. With an objective function based on the doses to the PTV, it is possible for a plan that gives excess fluence to the skin to have a lower objective function, and hence to be preferred in an optimization. We describe a technique of plan evaluation, based on analysis of a plan by recalculating several plans in which the isocentre has been offset by a distance equal to the CTV-PTV margin. We demonstrate that changes to a plan that reduce a PTV-based objective can give a worse dose distribution to the CTV when systematic and random set-up errors are accounted for, and increase skin dose. Several possible strategies for avoiding this problem are discussed, including the use of the skin as an organ at risk, modification of the PTV to avoid the skin, and the use of 'pretend bolus' applied in planning but not in treatment. The latter gave the best results. The possibility of using the evaluation method itself, as the basis of an objective function for optimization, is discussed.

Algorithms↗
PubMed2004

Calibration of Kodak EDR2 film for patient skin dose assessment in cardiac catheterization procedures.

Kodak EDR2 film has been calibrated across the range of exposure conditions encountered in our cardiac catheterization laboratory. Its dose-response function has been successfully modelled, up to the saturation point of 1 Gy. The most important factor affecting film sensitivity is the use of beam filtration. Spectral filtration and kVp together account for a variation in dose per optical density of -10% to +25%, at 160 mGy. The use of a dynamic wedge filter may cause doses to be underestimated by up to 6%. The film is relatively insensitive to variations in batch, field size, exposure rate, time to processing and day-to-day fluctuations in processor performance. Overall uncertainty in the calibration is estimated to be -20% to +40%, at 160 mGy. However, the uncertainty increases at higher doses, as the curve saturates. Artefacts were seen on a number of films, due to faults in the light-proofing of the film packets.

Body Burden↗
PubMed2001

Green tea polyphenol (-)-epigallocatechin-3-gallate treatment of human skin inhibits ultraviolet radiation-induced oxidative stress.

The use of naturally occurring botanicals with substantial antioxidant activity to afford protection to human skin against UV damage is receiving increasing attention. The green tea constituent (-)-epigallocatechin-3-gallate (EGCG) is a potent antioxidant and has shown remarkable preventive effects against photocarcinogenesis and phototoxicity in mouse models. In this study we have investigated the effects of topical application of EGCG, the major polyphenol present in green tea, to human skin before UV irradiation on UV-induced markers of oxidative stress and antioxidant enzymes. Using immunohistochemistry and analytical enzyme assays, we found that application of EGCG (mg/cm(2) skin) before a single UV exposure of 4x minimal erythema dose (MED) markedly decreases UV-induced production of hydrogen peroxide (68-90%, P < 0.025-0.005) and nitric oxide (30-100%, P < 0.025-0.005) in both epidermis and dermis in a time-dependent manner. EGCG pretreatment also inhibits UV-induced infiltration of inflammatory leukocytes, particularly CD11b(+) cells (a surface marker of monocytes/macrophages and neutrophils), into the skin, which are considered to be the major producers of reactive oxygen species. EGCG treatment was also found to inhibit UV-induced epidermal lipid peroxidation at each time point studied (41-84%, P < 0.05). A single UV exposure of 4x MED to human skin was found to increase catalase activity (109-145%) and decrease glutathione peroxidase (GPx) activity (36-54%) and total glutathione (GSH) level (13-36%) at different time points studied. Pretreatment with EGCG was found to restore the UV-induced decrease in GSH level and afforded protection to the antioxidant enzyme GPx. Further studies are warranted to study the preventive effects of EGCG against multiple exposures to UV light of human skin.

Adult↗
PubMed2001

Induction of p53 expression in skin by radiotherapy and UV radiation: a randomized study.

BACKGROUND: p53 protein plays an important role in the response to DNA damage, and radiotherapy can cause radiation dermatitis. p53 and p21 levels increase in vitro when DNA is damaged by UVA, UVB, or gamma-radiation. To determine whether this response occurs in human skin and predicts the level of radiation dermatitis, we investigated levels of p53 and p21 in skin exposed to different types of radiation as part of a randomized study of women with breast cancer to evaluate topical steroid or emollient cream treatments for radiation dermatitis of their irradiated breast. METHODS: After surgery but before receiving tangential 5-mV photo-beam radiotherapy (2 Gy and 54 Gy) to the affected breast parenchyma, multiple areas on the backs of 50 women were irradiated with UVA and other areas were irradiated with UVB. Skin biopsy samples were taken from areas of normal unirradiated skin and all irradiated areas, and p53 and p21 were detected immunohistochemically. All statistical tests are two-sided. RESULTS: In skin irradiated with UVA or UVB, medians of 4.4% (range = 0%-40.5%) or 45.5% (range = 5.3%-74.6%) p53-positive keratinocytes, respectively, were observed. Radiotherapy produced medians of 31.0% (range = 0%-79.3%) p53-immunoreactive cells after 2 Gy of radiation and 83.2% (range = 37.6%-95.2%) after 54 Gy of radiation. Despite large interindividual differences in p53 response, comparable increases in epidermal p53 response were independent of the type of radiation. A correlation between p53 and p21 was also evident (r(s) =.78). In breast skin, there was no association between the p53 response and the degree of erythema (a measure of radiation dermatitis) and no statistically significant difference between treatment arms and p21/p53 responses. CONCLUSIONS: Individual responses to radiation-induced DNA damage varied widely and may be independent of the type of radiation. The epidermal p53 response does not predict the degree of radiation dermatitis.

Aged↗