Dataset Information

Erythematous reactions to two ultraviolet excimer therapy devices with different irradiance levels: Reconsidering the reciprocity law.

ABSTRACT:

Background

Few studies have examined the effectiveness of the reciprocity law in ultraviolet excimer therapy. This study aimed to examine the difference in erythematous reaction in human skin when the irradiance of ultraviolet excimer treatment devices differed while the irradiation dose was constant.

Materials and methods

This study, conducted at the Department of Dermatology, Chiba University, included 15 healthy adults aged 20-65 years (mean age, 46.3 years; seven men). Using ultraviolet excimer treatment devices with different irradiances (50 or 150 mW/cm² ), the upper abdomen of each participant was irradiated with ultraviolet light at set irradiation doses (80, 100, 120, 140, 160, 180, and 200 mJ/cm² ). The erythema index of each irradiated site was measured using a melanin- and erythema-measuring device, and the difference in erythema index before and 24 h after irradiation was the primary endpoint.

Results

The change in erythema index was significantly higher for an irradiance of 150 mW/cm² . Significant differences (p < 0.05) were observed between these irradiance levels at irradiation doses of 100-200 mJ/cm² .

Conclusions

Even for the same irradiation dose, stronger erythematous reactions occurred at higher irradiances in ultraviolet excimer treatment. This suggests that the reciprocity law may not always hold true in excimer therapy.

SUBMITTER: Togawa Y

PROVIDER: S-EPMC10415868 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Publications

Erythematous reactions to two ultraviolet excimer therapy devices with different irradiance levels: Reconsidering the reciprocity law.

Togawa Yaei Y Kawashima Shusuke S Nagai Kazue K Kawasaki Yohei Y Matsue Hiroyuki H

Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) 20230801 8

<h4>Background</h4>Few studies have examined the effectiveness of the reciprocity law in ultraviolet excimer therapy. This study aimed to examine the difference in erythematous reaction in human skin when the irradiance of ultraviolet excimer treatment devices differed while the irradiation dose was constant.<h4>Materials and methods</h4>This study, conducted at the Department of Dermatology, Chiba University, included 15 healthy adults aged 20-65 years (mean age, 46.3 years; seven men). Using u ...[more]

PMID: 37632181

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Project description:BackgroundPulsed ultraviolet (UV)-C light sources, such as excimer lasers, are used in emerging non-thermal food-decontamination methods and also have high potential for use in a wide range of microbial decontamination applications. The acaricidal effect of an experimental UV-C irradiation device was assessed using female adults and eggs of a model organism, the two-spotted spider mite Tetranychus urticae.MethodsUV-C light was generated by a pulsed krypton fluoride excimer laser operating at 248-nm emission wavelength. The pulse energy and pulse repetition rate were 5 mJ and up to 100 Hz, respectively. The distance from the light source to the target was 150 mm; the target surface area was 2.16 cm2. The exposure time for the mites and fresh eggs varied from 1 to 4 min at 5-300 mW, which corresponded to UV doses of 5-80 kJ/m2. Post-irradiation acaricidal effects (mite mortality) were assessed immediately and also measured at 24 h. The effects of UV-C irradiation on the hatchability of eggs were observed daily for up to 12 days post-irradiation.ResultsThe mortality of mites at 5 and 40 kJ/m2 was 26% and 92%, respectively. Mite mortality reached 98% at 80 kJ/m2. The effect of exposure duration on mortality was minimal. The effect of irradiation on egg hatchability was even more significant than that on adult mite mortality, i.e. about 100% egg mortality at an accumulated dose of as little as 5 kJ/m2 for each exposure time.ConclusionsA high rate of mite mortality and lethal egg damage were observed after less than 1 min of exposure to 5 mJ UV-C pulsed irradiation at 60 Hz. Pending further developments (such as beam steering, beam shaping and miniaturisation) and feasibility studies (such as testing with mites in real-life situations), the reported results and characteristics of the UV-C generator (modulation of energy output and adaptability to varying spot sizes) open up the use of this technology for a vast field of acaricidal applications that require long-range radiation.

Project description:(1) The effects of facilitation on the structure and dynamics of plant populations have not been studied so widely as competition. The UV-B radiation, as a typical environmental factor causing stress, may result in direct stress and facilitation. (2) The effects of UV-B radiation on intraspecific competition and facilitation were investigated based on the following three predictions on self-thinning, size inequality, and phenotypic plasticity: i) Self-thinning is the reduction in density that results from the increase in the mean biomass of individuals in crowded populations, and is driven by competition. In this study, the mortality rate of the population is predicted to decrease from UV-B irradiance. ii) The size inequality of a population increases with competition intensity because larger individuals receive a disproportionate share of resources, thereby leaving limited resources for smaller individuals. The second hypothesis assumes that direct stress decreases the size inequality of the population. iii) Phenotypic plasticity is the ability to alter one's morphology in response to environmental changes. The third hypothesis assumes that certain morphological indices can change among the trade-offs between competition, facilitation, and stress. These predictions were tested by conducting a field pot experiment using mung beans, and were supported by the following results: (3) UV-B radiation increased the survival rate of the population at the end of self-thinning. However, this result was mainly due to direct stress rather than facilitation. (4) Just as competitor, facilitation was also asymmetric. It increased the size inequality of populations during self-thinning, whereas stress decreased the size inequality. (5) Direct stress and facilitation influence plants differently on various scales. Stress inhibited plant growth, whereas facilitation showed the opposite on an individual scale. Stress increased survival rate, whereas facilitation increased individual variability on the population scale. (6) Trade-offs between competitions, facilitation, and direct stress varied in different growing stages.

Dataset Information

Erythematous reactions to two ultraviolet excimer therapy devices with different irradiance levels: Reconsidering the reciprocity law.

Background

Materials and methods

Results

Conclusions

Publications

Erythematous reactions to two ultraviolet excimer therapy devices with different irradiance levels: Reconsidering the reciprocity law.

Similar Datasets

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