Background: In order to investigate the combination effect of anticancer drugs and X-ray irradiation on neurotoxic side-effects (neurotoxicity), a method that provides homogeneously X-ray-irradiated cells was newly established. Materials and Methods: PC12 cell suspension was irradiated by X-ray (0.5 Gy) in serum-supplemented medium, immediately inoculated into 96-microwell plates and incubated overnight. The medium was replaced with fresh serum-depleted medium containing 50 ng/ml nerve growth factor to induce differentiation toward nerve-like cells with characteristic neurites according to the overlay method without changing the medium. The differentiated cells were treated by anticancer drugs as well as antioxidants, oxaliplatin or bortezomib, and the viable cell number was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide method. Results: Antioxidants and anticancer drugs were cytotoxic to differentiating PC12 cells. Combination of anticancer drugs and X-ray irradiation slightly reduced cell viability. Conclusion: The present 'population irradiation method' may be useful for the investigation of the combination effect of X-ray irradiation and any pharmaceutical drug. X-Rays are used for many purposes in various fields. This includes the visualization of the distribution and therapeutic effects of drugs by X-ray computed tomography (1); the assessment of chemical element changes by energy dispersive X-ray spectrometry (2); the analysis of crystal structure by Xray diffraction (3); the analysis of oral mucosal distribution of trace metal elements by X-ray fluorescence with synchrotron radiation and particle-induced X-ray emission, and the estimation of chemical states of elements by X-ray absorption fine-structure analysis (4); the visual inspection of passenger baggage in airports by X-ray images (5); and therapeutic applications in medicine (6). Radiation, such as X-rays, and drugs, are reported to exert dose-dependent biphasic effects (7). X-Ray irradiation has been reported to stimulate the production of reactive oxygen-species such as superoxide and nitrite (8, 9), the secretion of Fas ligand (10), the accumulation of cells in the G 2 +M phase in the cell cycle (11), and the shortening of telomeres (12). On the other hand, at lower doses of X-irradiation, beneficial effects (known as hormesis) can be induced. For example, Xirradiation at 10 mGy (but not 50 or 100 mGy) reduced the frequency of micronucleated cells in human lymphocytes to below the spontaneous level (13). Recently, we discovered that among anticancer drugs, platinum preparations (cisplatin, carboplatin, oxaliplatin) and proteasome inhibitor bortezomib showed potent cytotoxicity not only against normal oral keratinocytes (14) but also against PC12 nerve-like cells (Iijima et al., unpublished data). The neurotoxicity of anticancer agents and X-ray irradiation is a recent research topic in today's aging society. In the present study, we investigated whether cytotoxic doses of X-ray irradiation further augment neurotoxicity...

Background/Aim: Chitosan-coated iron oxide nanoparticles (Chi-NP) have gained attention because of their biocompatibility, biodegradability, low toxicity and targetability under magnetic field. In this study, we investigated various biological properties of Chi-NP. Materials and Methods: Chi-NP was prepared by mixing magnetic NP with chitosan FL-80. Particle size was determined by scanning and transmission electron microscopes, cell viability by MTT assay, cell cycle distribution by cell sorter, synergism with anticancer drugs by combination index, PGE 2 production in human gingival fibroblast was assayed by ELISA. Results: The synthetic process of Chi-NP from FL-80 and magnetic NP increased the affinity to cells, up to the level attained by nanofibers. Upon contact with the culture medium, Chi-NP instantly formed aggregates and interfered with intracellular uptake. Aggregated Chi-NP did not show cytotoxicity, synergism with anticancer drugs, induce apoptosis (accumulation of subG1 cell population), protect the cells from X-ray-induced damage, nor affected both basal and IL-1β-induced PGE 2 production. Conclusion: Chi-NP is biologically inert and shows high affinity to cells, further confirming its superiority as a scaffold for drug delivery.

Background/Aim: COVID-19 pandemic caused the rapid dissemination of ultraviolet C (UVC) sterilization apparatuses. Prolonged exposure to UVC, however, may exert harmful effects on the human body. The aim of the present study was to comprehensively investigate the anti-UVC activity of a total of 108 hot-water soluble herb extracts, using human dermal fibroblast and melanoma cell lines, for the future development of skin care products. Materials and Methods: Exposure time to UVC was set to 3 min, and cell viability was determined using the MTT assay. Anti-UVC activity was determined using the selective index (SI), a ratio of 50% cytotoxic concentration for unirradiated cells to 50% effective concentration that restored half of the UVC-induced decrease of viability. Results: Dermal fibroblasts at any population doubling level were more resistant to UVC irradiation than melanoma cells. Both 49 herb extracts recommended by Japan Medical Herb Association (JAMHA) and 59 additional herb extracts showed comparable anti-UVC activity. SI values of selected herbs (Butterbur, Cloves, Curry Tree, Evening Primrose, Rooibos, Stevia, Willow) were several-fold lower than those of vitamin C and vanillin. Their potent anti-UVC activity was maintained for at least 6 h post irradiation, but declined thereafter to the basal level, possibly due to cytotoxic ingredients. Conclusion: UVC sensitivity may be related to the growth potential of target cells. Removal of cytotoxic ingredients of herb extracts may further potentiate and prolong their anti-UVC activity.SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection caused the coronavirus disease of 2019 (COVID-19) pandemic, accompanied by serious morbidity and mortality (1). This triggered the rapid dissemination of various types of ultraviolet C (UVC) sterilization apparatuses in hospital emergency department waiting rooms, clinics, nursing homes, prison common areas, public libraries (providing the sterilization box for cleaning books), schools, restaurants, and bedrooms (2). While UVC has strong bactericidal (3) and virucidal (4) activity, the prolonged exposure to UVC may have harmful effects on the human body, causing various diseases such as skin cancer (5) and cataracts (6). Therefore, the search for nontoxic UVC protective substances is crucial. Sakagami et al. recently reported that (i) human normal cells (gingival, periodontal, and dermal fibroblasts and pulp cells] are generally resistant to UVC irradiation, as compared with human cancer cell lines (oral squamous cell carcinoma, lung cancer, glioblastoma, leukemia, and melanoma) (7); and that (ii) 1540