Maki Aihara

Inactivation of Vibrio parahaemolyticus in Effluent Seawater by Alternating-Current Treatment

ABSTRACT Vibrio parahaemolyticus, the cause of gastroenteritis in humans, was inactivated by alternating low-amperage electricity. In this study, the application of alternating low-amperage electric treatment to effluent seawater was investigated for the large-scale disinfection of seawater. This method was able to overcome the problem of chlorine generation that results from treatment with continuous direct current. In conclusion, our results showed that alternating-current treatment inactivates V. parahaemolyticus in effluent seawater while minimizing the generation of chlorine and that this alternating-current treatment is therefore suitable for practical industrial applications.

In Vitro Bioassay of Endotoxin Using Fluorescein as a pH Indicator in a Macrophage Cell Culture System

Based on the biological activity of endotoxin, we propose a possible new method for detecting endotoxin using a pH-indication system of macrophage culture media. After RAW 264.7 macrophage cells were treated with lipopolysaccharide (LPS), the addition of fluorescein to the LPS-treated media reproductively reduced its absorption and emission spectra (it was a dose-dependent reduction). The advantages of this LPS-detection method were compared with the Limulus Amebocyte Lysate (LAL) test by using purified bacterial LPS (Salmonella minnessota, Escherichia coli, and Pseudomonas aeruginosa). Additionally, the absorption and fluorescence intensity of fluorescein, following treatment of RAW 264.7 cells with a high concentration of Staphylococcus aureus (Gram-positive, lysed bacteria), could not generally be detected by the LAL test, but they were found to be reduced, in a dose-response relationship, with this new system. The macrophage culture system-method might be a good supplement to the LAL assay for detection of LPS, Gram-negative and Gram-positive bacteria.

The Influences of β-Glucan Associated with BMP-7 on MC3T3-E1 Proliferation and Osteogenic Differentiation

b-glucan, an immunomodulator, can selectively enhance the immunobiological activities of neutrophils and macrophages without stimulating proinflammatory cytokine production. Biologic response modifiers, like beta-glucan, will modulate immunity, modify neoplastic disease and increase resistance to microbial challenge. Therefore, beta-glucan polymers can be applied in bone induction and regeneration model and have a possibility of association with bone morphogenetic protein (BMP) because of tissue-regenerative and antimicrobial effects of those polymers. In this report, we studied an E. coli expression system for BMP-7 production and the biological activities of b-glucan associated with BMP-7. The proliferation of MC3T3-E1 osteoblastic cells was enhanced by treatment with Aureobasidium b-glucan, while neither mushroom b-glucan nor barley b-glucan increased the cell proliferation. Mushroom b-glucan alone or associated with BMP-7 increased alkaline phosphatase (ALP) activity of MC3T3-E1 cells, one of the osteoblast phenotype markers, but the other b-glucans did not affect ALP activity of the cells. In mineralization assay, a highly significant increase in nodular staining was observed in cultures treated with both mushroom and Aureobasidium b-glucans in the presence of BMP-7 compared with nontreated controls, while barley b-glucan showed a significant decrease in nodule number compared with cultures treated only with BMP-7.

Computer-Assisted Image Processing Techniques for Quantitative Analysis of Cell Migrations on Collagen-Coated Glass

In this study, a computer-assisted cell tracking system including an automatic image processing program for rapid and precise analysis of cell migration in various conditions was self-designed and L-929 cell migration on the glass coated with type I collagen was examined using this cell tracking system. Furthermore, computer-based image processing software, with the capture program to choose the capture interval and period, and analysis techniques were developed for quantitative analysis of the cell migration on extracellular matrices. The results showed that the migration speed of L-929 cells on the collagen-coated glass was significantly (p < 0.05) increased compared to the non-coated control. On the morphological observations, it was showed that the cells on the collagen-coated glass looked much healthier than those on the control. These results suggested that this cell tracking system would provide tools for the analysis of cell migration in various in vitro conditions and might be effective enough to evaluate various biological events including embryonic development as well as physiological and pathological tissue reorganization.