Accumulated melanin in molds provides wavelength-dependent UV tolerance.

Fungal contamination poses a serious threat to public health and food safety because molds can grow under stressful conditions through melanin accumulation. Although ultraviolet (UV) irradiation is popular for inhibiting microorganisms, its effectiveness is limited by our insufficient knowledge about UV tolerance in melanin-accumulating molds. In this study, we first confirmed the protective effect of melanin by evaluating the UV sensitivity of young and mature spores. Additionally, we compared UV sensitivity between spores with accumulated melanin and spores prepared with melanin biosynthesis inhibitors. We found that mature spores were less UV-sensitive than young spores, and that reduced melanin accumulation by inhibitors led to reduced UV sensitivity. These results suggest that melanin protects cells against UV irradiation. To determine the most effective wavelength for inhibition, we evaluated the wavelength dependence of UV tolerance in a yeast (Rhodotorula mucilaginosa) and in molds (Aspergillus fumigatus, Cladosporium halotolerans, Cladosporium sphaerospermum, Aspergillus brasiliensis, Penicillium roqueforti, and Botrytis cinerea). We assessed UV tolerance using a UV-light emitting diode (LED) irradiation system with 13 wavelength-ranked LEDs between 250 and 365 nm, a krypton chlorine (KrCl) excimer lamp device, and a low pressure (LP) Hg lamp device. The inhibition of fungi peaked at around 270 nm, and most molds showed reduced UV sensitivity at shorter wavelengths as they accumulated pigment. Absorption spectra of the pigments showed greater absorption at shorter wavelengths, suggesting greater UV protection at these wavelengths. These results will assist in the development of fungal disinfection systems using UV, such as closed systems of air and water purification.

Development of a standard evaluation method for microbial UV sensitivity using light-emitting diodes.

Ultraviolet (UV) light is an effective disinfection method. In particular, UV light-emitting diodes (UV-LEDs) are expected to have many applications as light sources owing to their compact form factor and wide range of choices of wavelengths. However, the UV sensitivity of microorganisms for each UV wavelength has not been evaluated comprehensively because standard experimental conditions based on LED characteristics have not been established. Therefore, it is necessary to establish a standard evaluation method based on LED characteristics. Here, we developed a new UV-LED device based on strictly controlled irradiation conditions using LEDs for each wavelength (250-365 nm), checked the validity of the device characteristics and evaluated the UV sensitivity of Escherichia coli using this new evaluation method. For this new device, we considered accurate irradiance, accurate spectra, irradiance uniformity, accurate dose, beam angle, surrounding material reflections, and sample condition. From our results, the following UV irradiation conditions were established as standard: 1 mW/cm2 irradiance, bacterial solution with absorbance value of A600 = 0.5 diluted 10 times solution, solution volume of 1 mL, working distance (WD) of 100 mm. In order to compare the effects of irradiation under uniform conditions on inactivation of microorganisms, we assessed inactivation effect of E. coli by LED irradiation at each wavelength using the U280 LED as a standard wavelength. The inactivation effect for U280 LED irradiation was -0.95 ± 0.21 log at a dose of 4 mJ/cm2. Under this condition of dose, our results showed a high wavelength dependence of the inactivation effect at each UV wavelength peaking at 267 nm. Our study showed that this irradiation system was validated for the standard UV irradiation system and could be contributed to the establishment of food and water hygiene control methods and the development of equipment for the prevention of infectious diseases.

Reliability and validity of the Japanese version of the Quality of Life Index for patients with cancer.

This study was designed to evaluate the psychometric properties of the newly completed Japanese translation of the Ferrans and Powers Quality of Life Index Cancer Version III (QLI). Using a cross-sectional descriptive design, 136 ambulatory patients with gastrointestinal cancer (55 receiving chemotherapy, 76 with stable health status after treatment, and five status not known) completed a questionnaire at a one-time point, and 26 patients (stable health status) completed the questionnaire again 2 weeks later. Internal consistency reliability was supported by Cronbach's α of .96 for the total scale, with subscales ranging from .83 to .93. A test-retest correlation of 0.76 (total scale) provided evidence of stability reliability over a 2-week period, with subscale retest correlations ranging from 0.70 to 0.83. Confirmatory factor analysis showed the same four domains for the Japanese translation as the original QLI, supporting construct validity. We also assessed construct validity by examining the relationships between the Japanese QLI and six other concepts known to be related to the quality of life. As hypothesized, all correlations were moderate and in the expected direction (pain -0.39, anxiety -0.54, depression -0.63, stress -0.51, pain interfering with functioning -0.52, and general health 0.62). This evidence of the reliability and validity of the Japanese translation of the QLI supports its use in research and clinical practice to evaluate the impact of cancer and treatment. This new translation can be used to assess the patient's perspective of their quality of life, both within Japan and in cross-cultural studies with the QLI in other languages.