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ABSTRACT: To verify the usefulness of the Veris III system, which is said to be problematic in clinical applications for recording multifocal electroretinograms (mfERG) by an ophthalmologist.
A test wave was input to the system and the data were analyzed using Veris Science software. The items tested were overlapping, spatial averaging, combination procedures, and emission properties of the cathode ray tube (CRT) monitor (B 4).
Overlapping was not observed under the standard stimulus conditions. The data resulting from both spatial averaging and combination procedures coincided with the theoretical calculated data defined by both procedures. Analysis of the emission properties of the CRT monitor showed that it took 85 mu seconds from the beginning to the end of the bright emission.
No clinical problems were found in the M-sequence program, the spatial averaging procedure, or the combination procedure using several test waves. It is necessary to pay attention to the configuration of pattern stimulation on the CRT monitor (B 4), because it has a very steep emission during a very short time.
Nippon Ganka Gakkai zasshi 10/2007; 111(9):722-7.
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ABSTRACT: As tri-n-butyltin (TBT), one of the environmental pollutants, is accumulated in wild animals, concern regarding the toxicity of TBT in both wildlife and human is increasing. TBT has been reported to increase intracellular Ca(2+) concentration in several types of cells. In order to examine how Ca(2+) is involved in TBT-induced cell death, the effect of TBT on rat thymocytes has been compared with that of A23187, a calcium ionophore, under various concentrations of external Ca(2+) using a flow cytometer and fluorescent probes. Although both TBT and A23187 were toxic to cells under normal Ca(2+) condition, under external Ca(2+)-free condition the cytotoxic action of TBT was potentiated without changing the threshold concentration while that of A23187 was completely abolished. A23187 attenuated the TBT-induced descent in cell viability under normal Ca(2+) concentration despite intracellular Ca(2+) concentration was increased. As external Ca(2+) concentration increased, the TBT-induced increase in number of dead cells gradually decreased whereas the number of cells in an early stage of apoptosis increased. Results suggest that Ca(2+) has contradictory actions on the process of TBT-induced cell death in rat thymocytes.
Environmental Toxicology and Pharmacology 01/2003; 13(1):29-36. · 1.47 Impact Factor
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Hiromi Hayashi,
Hitomi Sakai,
Wakako Minakuchi-Fujiwara,
Miki Takayama,
Michiko Nakamura-Murata,
Ryoko Kamo,
Kanako Funakoshi,
Keisuke Fukumoto,
Kaori Kanemaru,
Hideyuki Nakagawa,
Yasuo Oyama,
Nobuyuki Shinohara,
Yoshihiro Ito
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ABSTRACT: Cell growth of anaerobic protozoan Tritrichomonas foetus was analyzed. This protozoan usually proliferates in extremely high density, but protozoan parasites were dispersed uniformly in F-bouillon medium and cell division stopped temporarily. However, nuclear fission continued and giant polynucleated cells formed. Later, cell division resumed and cells returned to normal form. In conditioned medium, cytokinesis of the dispersed parasites did not stop. Results indicated that T. foetus cells secreted an extracellular factor that influenced cytokinesis.
ZOOLOGICAL SCIENCE 11/2002; 19(10):1089-94. · 0.95 Impact Factor
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ABSTRACT: The biomedical and industrial uses of organobismuth compounds have become widespread, although there is limited information concerning their cytotoxicity. Therefore, the actions of triphenylbismuth on rat thymocytes were examined using a flow cytometer with ethidium bromide, annexin V-FITC, fluo-3-AM, and 5-chloromethylfluorescein (5CMF) diacetate. Triphenylbismuth at 3-30 microM increased the population of cells stained with ethidium, indicating a decrease in cell viability. Organobismuth at 30 microM increased the population of cells positive to annexin V, suggesting an increase in the population of apoptotic cells. Triphenylbismuth at 3 microM or more decreased cellular glutathione content (5CMF fluorescence intensity) and increased intracellular Ca(2+) concentration ([Ca(2+)](i), fluo-3 fluorescence intensity) in a dose-dependent manner. Because an increase in [Ca(2+)](i) is linked to cell death or cell injury and a decrease in cellular glutathione content increases cell vulnerability to oxidative stress, the triphenylbismuth-induced changes in cellular parameters may be responsible for triphenylbismuth-induced cytotoxicity. Bismuth chloride at 10-30 microM did not significantly affect cell viability. These results suggest that triphenylbismuth at micromolar concentrations exerts cytotoxic action on rat thymocytes, possibly related to a health hazard. Although the cytotoxicity of triphenylbismuth was less than that of triphenyltin, one of the environmental pollutants, it is necessary to direct our attention to the use and disposal of organobismuth compounds.
Environmental Toxicology 11/2002; 17(5):472-7. · 2.41 Impact Factor
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ABSTRACT: The effect of methylmercury on mouse thymocytes was examined using fluorescent dyes for membrane potential and intracellular Ca2+. Methylmercury at concentrations of 1 ωM or higher (up to 30 ωM) produced hyperpolarization in a dose-dependent fashion. Charybdotoxin and quinine, but not 4-aminopyridine and tetraethylammonium, greatly suppressed methylmercury-induced hyperpolarization. Removal of external Ca2+ reduced the degree of hyperpolarization. Pretreatment of thymocytes with A23187 under Ca2+-free conditions abolished the hyperpolarization induced by methylmercury. Under both normal and Ca2+-free conditions methylmercury increased the intracellular concentration of Ca2+. The results suggest that the increase in intracellular Ca2+ is mediated through a Ca2+ release from intracellular stores as well as through influx of external Ca2+. Therefore, it is likely that methylmercury increases the intracellular concentration of Ca2+, resulting in activation of Ca2+-dependent K+ conductance of mouse thymocytes.
European Journal of Pharmacology: Environmental Toxicology and Pharmacology.
