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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-N P was prepared by mixing magnetic NP with chitosan FL-80. P article size was determined by scanning and transmissione lectron microscopes, cell viability by MTT assay, cell cycle distribution by cell sorter, synergism with anticancer drugs bycombination index, PGE2 production in human gingivalfibroblast 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 cell population), protect the cells from X-ray-induced damage, nor affected both basal and IL-1β-induced PGE2 production. Conclusion: Chi-NP is biologically inert and shows high affinity to cells, further confirming its superiority as a scaffold for drug delivery. [ABSTRACT FROM AUTHOR]

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)-2,5-diphenyltetrazolium 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. [ABSTRACT FROM AUTHOR]

A higher proportion of polygynous ant species in northern areas suggests that cold climates select for increased queen number per colony. However, the types of social conditions within nests that allow polygynous species to inhabit cold climates are unclear. The Japanese twig-dwelling ant, Camponotus yamaokai Terayama & Satoh, 1990, which has on average two queens per colony, also inhabit colder areas than monogynous related species. C. yamaokai alates remain in natal colonies and always overwinter with workers. A previous study demonstrated that cohabitation by workers facilitates overwintering success of C. yamaokai queens. However, how queen number influences the survival of queens cohabitating with workers and the survival of other castes was not investigated. Here, we compared overwintering survival of queens and workers among experimental groups with different social structures. Wintering experiments revealed that queen survival did not differ between monogynous (one queen) and polygynous (two queens) groups but was correlated positively with worker number. Meanwhile both queen and worker number influenced worker survival, and these factors interacted with worker type (minor or major). Worker survival increased with increasing worker number, but the effect was more pronounced for major workers than for minor workers. With respect to queen number, minor workers survived longer in polygynous groups than in monogynous groups, whereas the opposite pattern was found in major workers. In other words, major worker mortality increased with increasing queen number. These results suggest that cohabitation with workers but not other queens facilitates queen survival, and that queen number increases survival in minor workers but increases mortality in major workers. Possible explanations for this latter pattern are discussed. [ABSTRACT FROM AUTHOR]