Biomedical subjects

Yukiko Doi

Publications and source records attributed to Yukiko Doi.

4 recordsLinked to original sources

PubMed2006

The direct and indirect effects of serofendic acid on neuroprotection.

Serofendic acid is a novel neuroprotective factor isolated from fetal calf serum. To elucidate the mechanisms how serofendic acid exerts neuroprotection, we examined its effects on glutamate-induced excito-toxicity in mouse cortical neurons. The effects of serofendic acid on inflammatory cytokine and neurotrophin production by glial cells were also examined to evaluate the indirect neuroprotection. Serofendic acid significantly and dose dependently increased survival of mouse cortical neurons after 10 muM N-methyl-D-asparate (NMDA) exposure. However, it did not affect production of inflammatory cytokines and neurotrophins by microglia as assessed by reverse transciption polymerase chain reaction (RT-PCR) for mRNA expression and ELISA for protein levels, though it suppressed tumor necrosis factor (TNF)-alpha production by astrocytes. Thus, serofendic acid works directly on neurons to protect against glutamate toxicity. Suppression of TNF-alpha production by astoryctes may also synergistically exert neuroprotective functions of serofendic acid. Serofendic acid may be of use for the future therapeutic strategy against ischemic and degenerative neurological disorders.

Animals↗

PubMed2005

Friction coefficient and structural transition in a poly(acrylamide) gel.

The friction coefficient between the polymer network of an opaque poly(acrylamide) gel and water is measured as a function of the mole fraction of cross linker. The friction coefficients of opaque gels are 4 to 5 orders of magnitude smaller than those of the transparent gels. This drastic decrease in friction occurs when the mole fraction of cross linker is 0.2. In opaque gels, the friction coefficient of gels and the mole fraction of cross linker are related by a power law. The network structure of the opaque gels used in the friction measurements is examined with a confocal laser scanning microscope. The opaque gel network consists of a fractal aggregate of colloidal particles. The radius of particles and the volume occupied by the particles depend on the mole fraction of cross linker. Both relationships are well described by the power laws. The power law of the friction coefficient is well explained in terms of the power laws of the structural parameters and the Stokes equation of the hydrodynamic friction for the spherical particle. It indicates that the friction of the opaque gel is determined simply by the structure of the polymer network.

Journal Article↗

PubMed2005

Real space structure of opaque gel.

The structure of the opaque poly(acrylamide) gels is studied by using a confocal laser scanning microscope. The polymer network of the gel consists of the fractal aggregate of the colloidal particles in the higher concentration region of the cross-linker. The diameter of the colloidal particle, which formed in the gel, increases from 180 to 420 nm with an increase of the concentration of cross-linker. On the other hand, the fractal dimensions of the aggregate remain constant, ranging from 1.5 to 1.7. The densities of the particle are calculated to be 0.7 and 1.2 x 103 kg/m3, which are >10 times larger than the average density of the polymer network of the gel. The results indicate that the monomer and the cross-linker are densely cross-linked into the particles.

Journal Article↗

PubMed2002

Both metabotropic glutamate I and II receptors mediate augmentation of dopamine release from the striatum in methamphetamine-sensitized rats.

The role of metabotropic glutamate receptor (mGluR) on dopamine overflow from the striatum was studied in methamphetamine (MAP)-sensitized rats. The increase of dopamine release by MAP was significantly inhibited by perfusion of a mGluR antagonist R,S-alpha-methyl-4-carboxyphenylglycine. The perfused mGluR agonist [S,3R-1-aminocyclopentane-1,3-dicarboxylic acid enhanced the dopamine level. The enhancement was significantly attenuated by co-perfusion of a mGluR group I antagonist (S)-4-carboxy-3-hydroxyphenylglycine or a mGluR group II antagonist R,S-a-methyl-4-tetrazolylphenylglycine. These suggest that both mGluR group I and II mediate augmentation of dopamine release in MAP-sensitized rats.

Animals↗