Toshiyuki Hosokawa

Mechanism of apoptosis induced by copper in PC12 cells

Copper, an essential trace element, induces apoptosis in mammalian cells. However, the precise mechanism of copper-induced apoptosis is still unclear. In this study, to determine the apoptotic pathway initiated by copper treatment, apoptotic factors such as Bax, Bad and Bcl-2, and the caspase family in PC12 cells treated with copper were measured by Western blot and RT-PCR analyses. The expression of Bax, Bad, cytochrome c and caspases 3 and 9 were increased by copper treatment. From these results, two pathways for copper-induced apoptosis were suggested. At first, an increase of Bax induces the release of cytochrome c from the mitochondria into the cytoplasm owing to binding to apoptotic activating caspase 9 leading to the activation of caspases 3. In the other pathway an increase of Bax and reactive oxygen species activates the release of AIF from the mitochondria. The AIF induces apoptosis via a caspase-independent pathway.

Immunohistochemical determination of the Wilson Copper-transporting P-type ATPase in the brain tissues of the rat.

Immunohistochemical localization of Copper-transporting P-type ATPase (ATP7B), a gene product responsible for Wilson disease, was visualized in the brain tissues of the Long-Evans agouti rat in detail using tissue-blotting technique and confocal laser microscopy. The ATP7B was intensely detected in neuronal cells of the hippocampal formation, olfactory bulbs, cerebellum, cerebral cortex and nuclei in the brainstem in which high amounts of copper and cuproenzymes, dopamine beta hydroxylase and Cu,Zn-superoxide dismutase (Cu,Zn-SOD) were detected. The present results suggest that ATP7B plays key roles in neurotransmissions of catecholamine pathway and preventing brain tissues from injury by superoxide radicals to regulate the cellular Cu concentration and/or activities of cuproenzymes related to neurotransmissions and a free radical metabolism. Furthermore, it is reasonable to assume that neurotoxicity due to abnormal copper accumulation or irregular regulation of cuproenzymes in the critical brain regions by mutation of the ATP7B gene leads to neurological failures of Wilson disease.

Combined effects of working environmental conditions in VDT work

The combined effects of city noise and luminance of the computer display were evaluated from the changes in lymphocytes and mental activities of participants. Healthy male students were tested under the following four experimental conditions: (1) a calculating task on a video display terminal (VDT) with luminance of 90 cd m-2 without city noise; (2) a calculating task on a VDT with luminance of 20 cd m-2 without city noise; (3) a calculating task on a VDT with luminance of 90 cd m-2 with city noise of 70 dB(A); and (4) a calculating task on a VDT with luminance of 20 cd m-2 with city noise of 70 dB(A). A visual reaction test (VRT) was performed, and critical flicker fusion frequency (CFF), heart rate (HR), numbers of circulating white blood cells (WBCs), lymphocyte subsets and subjective symptoms of fatigue were measured (1) before; (2) just after; and (3) 30 min after each 60 min test. Subjective symptoms of fatigue significantly increased just after experiments conducted under the two noisy conditions. VRT and CFF showed significant changes in the case of the highluminance display with noise. WBCs and neutrophils showed significant increases in the two quiet conditions. These results suggested that high luminance with noise had the most effect on subjective fatigue and mental activities.

Protective effect of taurine against renal interstitial fibrosis of rats induced by cisplatin

Abstract. This study was undertaken to investigate the effect of taurine on the infiltration of macrophages and the progression of renal interstitial fibrosis in the kidneys of rats treated with cisplatin (CDDP). Male rats in different groups were treated as follows: (1) saline as control, (2) CDDP and (3) CDDP plus taurine in drinking water. At weeks 2, 4 and 6 after the fifth CDDP injection, we examined platinum content, the kinetics of macrophages and the areas of fibrosis. In the histologic analyses, fibrotic areas were found to have developed around dilated or atrophic tubules in the corticomedullary junction in the kidneys of CDDP-treated rats, while CDDP-plus-taurine-treated rats showed a reduction of the extent and magnitude of damage. These findings reflect the fact that the percentage of fibrotic areas in the kidney of CDDP-plus-taurine-treated rats was significantly lower than in that of CDDP-injected rats throughout the recovery period (P<0.05). Compared with normal rats, the macrophages in CDDP-injected rats showed significant increases in number at weeks 2, 4 and 6 (P<0.05). In contrast, the number of macrophages in CDDP-plus-taurine-treated rats was significantly smaller than that of CDDP-injected rats. These results suggested that taurine suppressed the increase of infiltrating macrophages, and led to the attenuation of renal interstitial fibrosis (P<0.05).

Bisphenol-A suppresses neurite extension due to inhibition of phosphorylation of mitogen-activated protein kinase in PC12 cells

An endocrine disrupter, bisphenol-A is widely used in the production of plastics and coatings. Recently, it was reported that bisphenol-A affected neurotransmitters in the mammalian brain. On the basis of these reports, it was considered that bisphenol-A affected neuronal differentiation. In this study, the morphological changes in nerve growth factor (NFG)-induced differentiation caused by bisphenol-A were confirmed using a PC12 cell system. When a low concentration of bisphenol-A was added to medium containing NGF, it inhibited neurite extension. In addition, to clarify whether bisphenol-A affects the early and late stages of the NGF-signaling pathway in cell differentiation, changes of phosphorylation of MAP kinases and cAMP-response element binding protein (CREB) in PC12 cells treated with and without BPA in medium containing NGF were investigated using western blot analysis. As results, bisphenol-A significantly inhibited phosphorylation of CREB and ERK1/2 MAPK.

Comparison of general water quality of rivers in Indonesia and Japan

In Java and Kalimantan in Indonesia, river water plays important roles in human life; for example, for transportation, and economic activities of the inhabitants. However, industrial, agricultural and domestic water is discarded into rivers directly in many developing countries, including Indonesia, since drainage systems have not been completely constructed. In this study, to evaluate the water quality and to compare those levels of environmental contaminants in developing and developed countries, water quality and contents of endocrine disrupters were measured in a total of 64 water samples (Indonesia; 28 samples and Japan; 36 samples) from 53 sites. The results indicated that, rivers in both capital cities, Jakarta and Tokyo, were contaminated. Water in rivers in Indonesia was not so heavily polluted as in Japan. Pollution in the river water in Indonesia appeared to be caused by the lack of sewerage systems. In addition, the findings on endocrine disrupters indicated that the concentration of alkylphenol in water samples was large enough to affect living organisms.

Bcl-2-linked apoptosis due to increase in NO synthase in brain of SAMP10.

We examined the linkage of nitric oxide (NO)-induced apoptosis to acceleration of brain aging of senescence-accelerated mouse prone 10 (SAMP10). The expression of neuronal nitric oxide synthase (nNOS) increased in the cerebral cortex of the brain of SAMP10 in an age-dependent manner and significantly higher levels of neuronal nitric oxide synthase (nNOS) were observed in both young and old SAMP10 as compared to age-matched controls. Moreover, a lower level of anti-apoptotic protein Bcl-2 and a higher level of pro-apoptotic protein cytochrome c in cytosol were observed in SAMP10 compared to the control. However, there was no significant difference in the expression of pro-apoptotic protein p53 between SAMP10 and the control. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive apoptotic cells were more abundant in the cerebral cortex of aged SAMP10 than in the control. The present results suggest that an age-dependent increase of NO by up-regulation of nNOS promotes the Bcl-2-linked apoptosis in the cerebral cortex of SAMP10 and this may cause the acceleration of brain aging of SAMP10.

Removal of Cadmium and Chromium Ions Using Modified α, β, and γ-Cyclodextrin Polymers

The adsorption of cadmium and chromium from aqueous solutions with epichlorohydrin cross-linked α, β, and γ-cyclodextrin polymers (CDPs) was investigated under a wide range of experimental conditions including pH, metal concentration, and CDP amounts. Recent studies have shown that α, β, and γ-CDPs follow the Freundlich, Langmuir, and Brunauer–Emmett–Teller models and are capable of reducing heavy metal ion concentrations in water to desirable levels with enhanced sorption capabilities. The removal of cadmium and chromium achieved equilibrium in 4 h. The pH of effective cadmium removal was 6.5 to 7.5, and phosphate buffer favored the removal of cadmium in the presence of potassium ion. Chromium removal was optimal at pH 3.6 to 6.5. Current technologies can remove 99% cadmium ions from solution, yet this process is not very efficient for chromium ions. Furthermore, a small amount of CDPs can remove large quantities of heavy metal ions and can then be regenerated with acid for reuse. The present results are promising for using inexpensive CDPs as a low-cost material that is effective in remediating waters contaminated with heavy metal species. The sorption kinetics of CDPs along with the conditions to adsorb cadmium and chromium are reported here for the first time.

Basic study of the portable fatigue meter : effects of illumination, distance from eyes and age

Several aspects of a new, small and inexpensive fatigue assessment tool, the Portable Fatigue Meter (PFM), were studied. In the first experiment the effects of room illumination and distance between the PFM and the eyes on critical flicker fusion frequency (CFF) values were examined. The results revealed that the PFM CFF value varied significantly as a function of the distance between the indicator and the eyes, but it was not affected by room illumination. The effect of ageing on the PFM CFF value was assessed in a second experiment. The results suggested that PFM CFF values are significantly smaller in middle-aged females than in younger females.

2,4,5-Trichlorophenoxyacetic acid inhibits apoptosis in PC12 cells.

2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) is an endocrine disrupter that exerts cytotoxic effects on organisms. In this study, the influence of 2,4,5-T at low concentrations on apoptosis in PC 12 cells was investigated. Although no apoptotic features were observed in PC12 cells treated with 2,4,5-T, it inhibited the DNA fragmentation induced by serum deprivation. In addition, the cell viability of PC12 cells increased after treatment with 2,4,5-T. In conclusion, 2,4,5-T suppressed the apoptosis of the cultured cells. Since apoptosis is a morphological and biochemical description of a physiological mechanism of cell death that is commonly associated with programmed events necessary for development of individuals and organs, the inhibitory effect of 2,4,5-T on apoptosis might cause serious damage to cell homeostasis and differentiation.