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M Tokuyama

Publications and source records attributed to M Tokuyama.

11 recordsLinked to original sources
PubMed2002

On the slow dynamics of density fluctuations near the colloidal glass transition.

Slow dynamics of density fluctuations near the colloidal glass transition is discussed from a new viewpoint by numerically solving a nonlinear stochastic diffusion equation for the density fluctuations recently proposed by one of the present authors (MT). The effects of spatial heterogeneities on the dynamics of density fluctuations are then investigated in an equilibrium system. The spatial heterogeneities are generated by the nonlinear density fluctuations, while in a nonequilibrium system they are described by a nonlinear deterministic equation for the average number density. The dynamics of equilibrium density fluctuations is thus shown to be quite different from that of nonequilibrium ones, leading to a logarithmic decay followed by less distinct alpha- and beta-relaxation processes.

Journal Article↗
PubMed2001

Disappearance of clonally expanded T cells after allogeneic leukocyte immunotherapy in peripheral blood of patients with habitual abortion.

Allogeneic leukocyte immunotherapy is often used to improve fertility of patients with habitual abortion (HA), which probably acts through immune-mediated mechanisms. However, the involvement of T cells is not clear. This study examined the effect of allogeneic immunotherapy on T cells of patients with HA. Peripheral blood mononuclear cells were obtained from 5 healthy women and 14 women with HA. RNA was isolated from mononuclear blood cells. Reverse transcription-polymerase chain reaction (RT-PCR), followed by single-strand conformational polymorphism (SSCP) were used to analyze the gene segments of T-cell receptor beta chain (TCRbetaV) variable regions. Oligoclonal accumulation of T cells was identified in peripheral blood of nonpregnant patients with a history of HA. It was also revealed, however, that immunostimulation reduced the number of accumulating T-cell clones (p = 0.0004). The results, together with the clinical effectiveness of immunotherapy, suggest that accumulation of T-cell clonotypes, which probably resulted from antigenic stimulation, is involved in the pathogenesis of HA.

Abortion, Habitual↗
PubMed2000

Slow dynamics of equilibrium density fluctuations in suspensions of colloidal hard spheres near the glass transition

A mean-field theory for the dynamics of equilibrium suspensions of colloidal hard spheres near the glass transition is presented based on the standpoint recently proposed by the present author. It is shown that although the relative magnitude of the density fluctuations to the mean equilibrium density is small even near the glass transition, they are described by a nonlinear stochastic equation which originates from the long-range hydrodynamic interactions between particles. A nonlinear mean-field equation for the particle mean-square displacement is then derived. This equation is used to analyze the recent experimental data for equilibrium colloidal suspensions. Analyses show that no divergence of the alpha- and beta-relaxation times is found in the experimental data, although the dynamic properties of the colloidal liquid exhibit a drastic slowing down in the so-called supercooled region.

Journal Article↗
PubMed1996

Time course analysis of alpha+ beta+ T cell clones during normal pregnancy.

During normal pregnancy, the fetus continues to mature inside the uterus without rejection. Inherited paternal antigens could be targeted by the maternal immune system. These reactions are believed to play a role in a number of habitual abortions. However, the precise maternal mechanisms preventing fetal tissue rejection are not well understood. Maternal T cells should recognize fetal antigens, so it is conceivable that antigen-specific T cell response to fetal antigens would occur by proliferation and accumulation of certain T cell clones in the pregnant mother. To elucidate the maternal immune response to the fetus we investigated the clonality of expanded T cells in peripheral blood lymphocytes in ten normal pregnant women. We employed reverse transcriptase-polymerase chain reaction for T cell receptor beta chain gene and subsequently analyzed the PCR product by single-strand conformation polymorphism analysis. A large number of distinctly expanded T cell clones were detected during pregnancy. These accumulations were observed as early as the ninth to tenth week post-conception and reached a maximum during the second trimester, suggesting the existence of dynamic antigen-specific T cell responses in the pregnant mother. However, after the 30th week of gestation, nearly all expanded T cell clones disappeared before parturition and the degree of clonality reached almost normal levels. Our results clearly indicate the existence of dynamic maternal T cell responses during pregnancy.

Adult↗
PubMed1992

Adrenal and circulating renin-angiotensin system in stroke-prone hypertensive rats.

The plasma and adrenal renin-angiotensin system in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats were examined in animals at 5, 11, 18, and 25 weeks of age. Plasma active renin was significantly increased in 18- and 25-week-old SHRSP with impaired renal function, whereas there was no difference in the plasma prorenin level or renal renin content between the two strains at all ages examined. Thus, the rate of activation of prorenin seems to be enhanced in the kidney of SHRSP with malignant hypertension. Adrenal renin contents were severalfold higher in SHRSP than WKY rats at all ages. However, adrenal angiotensin peptides were not increased in SHRSP aged 5 and 11 weeks. In 18-week-old SHRSP, adrenal angiotensin II (Ang II) and III (Ang III) levels were fourfold and 1.8-fold higher, respectively, than in WKY rats, accompanied by 1.5-fold higher plasma aldosterone. Increased adrenal angiotensin and plasma aldosterone were also found in 25-week-old SHRSP. Zonal distribution studies indicated that the elevated Ang II and III in SHRSP were derived mainly from the capsular tissue (the zona glomerulosa). To examine the contribution of circulating angiotensin to the adrenal angiotensin content, effects of bilateral nephrectomy on adrenal angiotensin and renin were examined in 18-week-old rats. At 24 hours after nephrectomy, plasma angiotensin, prorenin, and active renin were decreased to almost negligible concentrations. Conversely, in both adrenal capsular and decapsular tissues of SHRSP and WKY rats, neither angiotensin nor renin was significantly decreased after nephrectomy. These results suggest that the increase in adrenal capsular Ang II contents in SHRSP may be partly due to an enhanced local production of Ang II.

Adrenal Glands↗
PubMed1986

Chondroid syringoma in the hypothenar region.

A case of chondroid syringoma in the palm, probably the fourth to be reported, is presented. There was a large cystic cavity in the center of the tumor. The peculiar findings of hyaline, myxoid, or chondroid degeneration of the abundant stroma were observed histologically. This tumor should be considered in the differential diagnosis of painless, slow-growing palm tumors.

Adenoma, Sweat Gland↗