PubMed Health⌕ Search

Biomedical subjects

Y Senba

Publications and source records attributed to Y Senba.

8 recordsLinked to original sources
PubMed2003

Anisotropic ultrafast dissociation probed by the Doppler effect in resonant photoemission from CF4.

The resonant Auger spectrum from the decay of F 1s-excited CF4 is measured. Several lines exhibit a nondispersive kinetic energy as the exciting photon energy is tuned through the resonance region. The F 1s(-1) atomiclike Auger line is split into two components due to the emission of Auger electrons by a fragment in motion, when electron emission is observed along the polarization vector of the light. This Doppler splitting is direct evidence that the core excitation leads to T(d)-->C(3v) symmetry lowering, by elongation of a specific C-F bond preferentially aligned along the polarization vector of the incident photon.

Journal Article↗
PubMed2002

Interference effects in the resonant photoemission channels to the Ne+ 2p(4)(1D2)3p 2P, 2D, and 2F states in the Ne 1s excitation region.

We present measurements of total and partial photoionization cross sections of Ne in the 1s excitation region. The total cross section exhibits resonances with symmetric profiles, whereas the branching ratios to the Ne+ 2p(4)(1D2)3p 2P, 2D, and 2F states present strong oscillations in the interresonance regions. We prove that not only the interference between the direct and resonant ionization processes but also the interference among the ionization processes via different nonisolated resonances are important for this effect.

Journal Article↗
PubMed2001

A novel method of measuring hydroxyl radical-scavenging activity of antioxidants using gamma-irradiation.

A new method using ESR spin trapping was proposed for measuring the scavenging activity of antioxidants for the hydroxyl (OH) radical. (-)-Epigallocatechin gallate (EGCg) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) were used as the antioxidant and spin trapping agent, respectively. The conventional method using a Fenton reaction had problems associated with the estimation of activity, because the antioxidant disturbs the system for generating OH radical by coordinating on Fe2+ and by consuming H2O2, besides scavenging the spin adduct (DMPO-OH). Intense gamma-irradiation was therefore used to generate OH radicals, and the intensity decrease in DMPO-OH after irradiation was followed to obtain the rate constant for the scavenging of DMPO-OH by EGCg. The intensities were extrapolated to zero time to estimate the quantity of DMPO-OH formed during gamma-irradiation. By using these values, the reaction rate constant between OH radical and EGCg was calculated as a ratio to that of DMPO. It was shown that this method is useful for comparing the OH radical-scavenging activity of various antioxidants.

Antioxidants↗
PubMed2001

Spin-trapping study on the hydroxyl radical formed from a tea catechin-Cu(II) system.

A spin-trapping method was applied to examine the formation of the hydroxyl (OH) radical from a tea catechin-Cu(II) system to elucidate a previous result that some tea catechin-Cu(II) systems induced DNA scission. Three tea catechins, (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCg) and (-)-epicatechin (EC), were used. The spin-trapping agent, 5,5'-dimethyl-pyrroline-1-oxide (DMPO), was dissolved in a pH 9 phosphate buffer solution, then a catechin and Cu(II) were added in that order, and the ESR spectral change was monitored for one hour. The order of adding the catechin and Cu(II) was then reversed, and the ESR spectral change was again monitored to examine the coordinating activity of each catechin toward the Cu(II) ion and the effect on OH radical generation. The intensity changes of the spin adducts, DMPO-OH, DMPO-CH3 and DMPO-H, were analyzed, the results suggesting that the OH radical generated in the system decomposed DMPO, resulting in the formation of DMPO-CH3 and DMPO-H. The results show that EGC formed a stable complex with Cu(II) and generated the OH radical. EGCg seemed to have this activity, but the OH radical that was generated was scavenged by the gallate group existing in the complex. EC did not show strong coordinating and OH-generating activities. These characteristics of the three catechins are consistent with the results shown for DNA scission.

Catechin↗
PubMed1987

Effect of N-benzyl-D-glucamine dithiocarbamate on distribution and excretion of cadmium in rats.

The effect of sodium N-benzyl-D-glucamine dithiocarbamate (NBG-DTC) on the distribution and excretion of cadmium in rats exposed to cadmium and the chemical form and intestinal reabsorption of cadmium compound excreted in the bile were studied. Rats were injected intraperitoneally with 109CdCl2 (1 mg Cd and 10 microCi 109Cd/kg) and 24 h later, they were injected with NBG-DTC (400 or 1200 mumol/kg). The biliary excretion of cadmium was remarkably increased by intraperitoneally injection of NBG-DTC, while there was only a small increase in urinary excretion of cadmium. Such an enhancement effect of NBG-DTC on the biliary excretion of cadmium was much larger at the high dose (1200 mumol/kg) of NBG-DTC. The treatment with NBG-DTC significantly decreased the cadmium content in the liver at the dose of 1200 mumol/kg and did not result in the undesirable redistribution of cadmium to the tissues, such as brain, testes, heart and lung. In addition, it was found that the cadmium compound excreted in the bile was mainly characterized as cadmium-NBG-DTC and which was not reabsorbed from the intestinal tracts.

Animals↗
PubMedDate not supplied

Cytokeratin expression in subungual squamous cell carcinoma.

Cytokeratin expression in subungual squamous cell carcinoma was investigated in order to evaluate the origin and state of differentiation of the tumour. The tumour nests contained cytokeratin 14, 16 and 17, which were also expressed in the nail bed. Therefore, cytokeratin expression in subungual squamous cell carcinoma may reflect its indolent clinical prognosis.

Aged, 80 and over↗