Biomedical subjects

Kazuharu Yoshizuka

Publications and source records attributed to Kazuharu Yoshizuka.

4 recordsLinked to original sources

PubMed2006

Micro flow injection analysis combined with a separation technique for the urinary glucose assay.

A urinary glucose assay has been investigated, employing a micro flow injection analysis (microFIA) combined with a separation technique of glucose from the analyte. The adsorption part using activated alumina for the glucose in the analyte can be successively integrated onto a microFI chip. The selective adsorption-desorption of glucose in the artificial urine can progress on the adsorption part. Along with this selective preconcentration of glucose, the typical FI peak of glucose can be obtained just by feeding the sample and deionized water as an elutant sandwiched with the reagent on the carrier stream. The glucose concentration in artificial urine can be quantitatively determined with the present microFIA system, while the interference of other components coexisting in urine occurs in the case of the conventional FIA system without any separation part. The described method serves as a template for improving the selectivity for the analyte in the multi-component system.

Calibration↗

PubMed2005

Action of aluminum, novel TPC1-type channel inhibitor, against salicylate-induced and cold-shock-induced calcium influx in tobacco BY-2 cells.

Previously, effect of Al ions on calcium signaling was assessed in tobacco cells expressing a Ca2+-monitoring luminescent protein, aequorin and a newly isolated putative plant Ca2+ channel protein from Arabidopsis thaliana, AtTPC1 (two-pore channel 1). TPC1 channels were shown to be the only channel known to be sensitive to Al and they are responsive to reactive oxygen species and cryptogein, a fungal elicitor protein. Thus, involvement of TPC1 channels in calcium signaling leading to development of plant defense mechanism has been suggested. Then, the use of Al as a specific inhibitor of TPC1-type plant calcium channels has been proposed. Here, using transgenic tobacco BY-2 cells expressing aequorin, we report on the evidence in support of the involvement of Al-sensitive signaling pathway requiring TPC1-type channel-dependent Ca2+ influx in response to salicylic acid, a key plant defense-inducing agent, but not to an elicitor prepared from the cell wall of rice blast disease fungus Magnaporthe grisea. In addition, involvement of Al-sensitive Ca2+ channels in response to cold shock was also tested. The data suggested that the elicitor used here induces the Ca2+ influx via Al-insensitive path, while salicylic acid and cold-shock-stimulate the influx of Ca2+ via Al-sensitive mechanism.

Aequorin↗

PubMed2004

Advance of computational technology for simulating solvent extraction.

Due to recent significant enhancement of computer performance as well as computational techniques, molecular modeling and molecular simulations using computational chemistry can be achieved at the level of practical applications. Even in solvent extraction, the application of computational chemistry to simulations of extraction processes and the molecular design of high-performance extracting agents have gradually been increasing during the last decade. With combining the quantitative structure-property relationship between the molecule properties calculated by the computational chemistry methods and the thermodynamic properties obtained from experiments, researchers can precisely predict the next-generation of extracting agents and novel extraction processes. In this review, the concept of computational chemistry, such as molecular mechanics, molecular orbitals and molecular dynamics calculations, frequently used in the filed of solvent extraction, are outlined. Our systematic research on the solvent-extraction process utilizing MM, MO and MD calculations is also presented.

Journal Article↗

PubMedDate not supplied

Effects of fifteen rare-earth metals on Ca2+ influx in tobacco cells.

Effects of naturally existing rare-earth metals (REMs; atomic numbers, 39, 57-60, 62-71; Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), added as chloride salts, on Ca2+ influx induced by two different stimuli, namely hypoosmotic shock and hydrogen peroxide, were examined in a suspension-cultured transgenic cell line of BY-2 tobacco cells expressing aequorin, a Ca(2+)-sensitive luminescent protein in cytosol. Most REM salts used here showed inhibitory effect against Ca2+ influx. Especially NdCl3, SmCl3, EuCl3, GdCl3 and TbCl3 showed the most robust inhibitory action. In contrast, LuCl3, YbCl3, ErCl3 and YCl3 were shown to be poor inhibitors of Ca2+ influx. Since REMs tested here form a sequential range of ionic radii from 86.1 to 103.2 pm and the optimal range of ionic radii required for blocking the flux of Ca2+ was determined for each stimulus. The hydrogen peroxide-induced Ca2+ influx was optimally blocked by REMs with a broad range of ionic radii (93.8-101 pm) which is slightly smaller than or similar to that of Ca2+ (100 pm), while the hypoosmotically induced flux of Ca2+ was inhibited optimally by few REMs with a narrower range of relatively smaller ionic radii around that of Gd3+ (93.8 pm) a well known inhibitor of stretch-activated channels. Possible applications of such series of channel blockers in elucidation of plant signal transduction pathways are encouraged.

Biological Transport↗