Biomedical subjects

Kazuo Harada

Publications and source records attributed to Kazuo Harada.

24 records · Page 2Linked to original sources

PubMed2003

Decomposition of ethylene, a flower-senescence hormone, with electrolyzed anode water.

Electrolyzed anode water (EAW) markedly extended the vase life of cut carnation flowers. Therefore, a flower-senescence hormone involving ethylene decomposition by EAW with potassium chloride as an electrolyte was investigated. Ethylene was added externally to EAW, and the reaction between ethylen and the available chlorine in EAW was examined. EAW had a low pH value (2.5), a high concentration of dissolved oxygen, and extremely high redox potential (19.2 mg/l and 1323 mV, respectively) when available chlorine was at a concentration of about 620 microns. The addition of ethylene to EAW led to ethylene decomposition, and an equimolar amount of ethylene chlorohydrine with available chlorine was produced. The ethylene chlorohydrine production was greatly affected by the pH value (pH 2.5, 5.0 and 10.0 were tested), and was faster in an acidic solution. Ethylene chlorohydrine was not produced after ethylene had been added to EAW at pH 2.6 when available chlorine was absent, but was produced after potassium hypochlorite had been added to such EAW. The effect of the pH value of EAW on the vase life of cut carnations was compatible with the decomposition rate of ethylene in EAW of the same pH value. These results suggest that the effect of EAW on the vase life of cut carnations was due to the decomposition of ethylene to ethylene chlorohydrine by chlorine from chlorine compounds.

Electrolysis↗

PubMed2002

RNA LEGO: magnesium-dependent assembly of RNA building blocks through loop-loop interactions.

We describe the construction of nano-molecular assemblies using RNA building blocks the human immunodeficiency virus type 1 (HIV-1) dimerization initiation site (DIS) RNA, that forms stable base pairing through a magnesium-dependent loop-loop interaction ("kissing"). RNA building blocks containing two DIS or DIS-like hairpins connected by a two nucleotide linker self-assembled to form specific structures as observed by non-denaturing polyacrylamide gel electrophoresis (PAGE). Furthermore, observation of "real time" formation of the molecular assemblies by circular dichroism (CD) spectroscopy was attempted.

Base Sequence↗

PubMed2002

Microbial growth-promotion activity of 3-hydroxymonoazine- and N-hydroxydiazine-type heterocycles.

Three 3-hydroxymonoazine- and three N-hydroxydiazine-type heterocycles were tested whether they act as artificial siderophores toward Aureobacterium flavescens JG-9 (ATCC No. 25091). Among them, 1-hydroxy-3,5,6-trimethyl-2(1H)-pyrazinone (3) showed the highest growth-promotion activity comparable to desferrioxamine B (DFB), a natural trihydroxamate siderophore, at 48.5 microM or above, followed by 1-hydroxy-5,6-dimethyl-2(1H)-pyrazinone (2), 1-hydroxy-4,6-dimethyl-2(1H)-pyrimidinone (1), and 3-hydroxy-2-methyl-1-phenyl-4(1H)-pyridinone (6), while 3-hydroxy-1,2-dimethyl-4(1H)-pyridinone (5) did not show the bioactivity. These results are the first examples of N-hydroxydiazine-type heterocycles acting as artificial siderophores for A. flavescens JG-9.

Dose-Response Relationship, Drug↗

PubMed2002

Behavior of hydrogen peroxide in electrolyzed anode water.

Oxygen electrodes and spectrophotometric analysis have been used to evaluate the contribution of H2O2, in addition to available chlorine, to the high redox potential of electrolyzed anode water (EAW) with potassium chloride as an electrolyte. H2O2 was added externally to EAW, and the reaction between H2O2 and the available chlorine in the water was examined. EAW has a low pH (2.5), a high concentration of dissolved oxygen, and extremely high redox potentials (19 mg/l and 1,319 mV) when the available chlorine is at the concentration of about 580 microM. The addition of H2O2 to EAW led to H2O2 decomposition, and the amount of oxygen produced was equivalent to the amount of available chlorine. Oxygen production was reduced by ascorbic acid, and completely inhibited by 600 microM ascorbate. The rate of oxygen production was much affected by pH, and was slowest at or near pH 5.0. Rates were particularly high in alkaline solution. Absorbance at 235 nm (pH 3.0 and 5.0) and 292 nm (pH 10.0) decreased when H2O2 was added to the EAW at these pHs, and the extent of decrease was similar pH dependency to that of the oxygen production rate. Oxygen was not produced after H2O2 was added to EAW at pH 2.6 when available chlorine was absent, but oxygen was produced after potassium hypochlorite was added to such EAW. The oxygen production rates in EAW without available chlorine at pH 5.0 and 2.0, pH adjustment with KOH and HCl, respectively, were faster than the rate at pH 2.6, and fastest at pH 2.0. These results suggest that H2O2 or hydroxyl radicals derived from Fenton's reaction did not contribute to the high redox potential of EAW prepared with chlorine compounds as an electrolyte, so that the decomposition of H2O2 occurred rapidly with the reactions of chlorine and hypochlorite ions in EAW.

Ascorbic Acid↗

PubMedDate not supplied

Feasibility of polysaccharide hybrid materials for scaffolds in cartilage tissue engineering: evaluation of chondrocyte adhesion to polyion complex fibers prepared from alginate and chitosan.

The ideal cell-carrier material for cartilage regeneration should be one that closely mimics the natural environment in a living articular cartilage matrix. In the current study, we considered that alginate-based chitosan hybrid biomaterials could provide excellent supports for chondrocyte adhesion. To test this hypothesis, we investigated the adhesion behavior of rabbit chondrocytes onto an alginate polymer versus the adhesion of the chondrocytes onto some alginate-based chitosan hybrid polymer fibers in vitro. We demonstrated that the alginate-based chitosan hybrid polymer fibers showed much improved adhesion capacity with chondrocytes in comparison with alginate polymer fiber. Additionally, morphologic studies revealed maintenance of the characteristic round morphology of the chondrocyte and the dense fiber of the type II collagen produced by the chondrocytes in the hybrid polymer. On the basis of these results, we conclude that an alginate-based chitosan hybrid polymer fiber has considerable potential as a desirable biomaterial for cartilage tissue scaffolds.

Alginates↗

PubMedDate not supplied

In vivo 15N-enrichment of metabolites in suspension cultured cells and its application to metabolomics.

The incorporation of stable isotopes in suspension cultured cells is very simple and useful as a preliminary experimental method in the experimental scene of plant metabolomics to elucidate the metabolic profiles of mutants and transformants. Stable isotope methods would afford a dynamic explanation of turnover speed that would concern the metabolic flux. Utilization of suspension cultured cells allows genes to be easily induced or suppressed, culture conditions to be controlled, and samples to be easily prepared. Stable isotope tracing allows an index of metabolic flux to be obtained. Here we present an experiment feeding (15)N-labeled inorganic salts to Arabidopsis (cell line T87) and Coptis cultured cells. Results of a comparison of (15)N labeling ratios of amino acids derived from T87 cells cultured under light with those cultured in the dark corresponded to transcriptional expressions revealed by microarray experiments published previously, demonstrating the validity of this procedure. Furthermore, (15)N labeling ratios of Coptis cultured cells revealed arginine and lysine metabolism inhibition, which should result in inhibition of polyamine biosynthesis and cell division. This very simple experiment allowed us to uncover metabolic dynamic features of the plant cell. Therefore this method is very useful for forming working hypotheses and experimental design.

Amino Acids↗