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Biomedical subjects

T Matuzaki

Publications and source records attributed to T Matuzaki.

7 recordsLinked to original sources
PubMed2001

Orexin-A suppresses the pulsatile secretion of luteinizing hormone via beta-endorphin.

Orexins, the novel hypothalamic neuropeptides that stimulate feeding behavior, have been shown to suppress the pulsatile secretion of LH in ovariectomized rats. However, the mechanism of this action is still not clear. We examined the effect of naloxone, a specific opioid antagonist, on the suppression of the pulsatile secretion of LH by orexins to determine whether beta-endorphin is involved in this suppressive effect. We administered orexins intracerebroventricularly and injected naloxone intravenously in ovariectomized rats, and we measured the serum LH concentration to analyze the pulsatile secretion. Administration of orexin-A significantly reduced the mean LH concentration and the pulse frequency, but coadministration of naloxone significantly restored the mean LH concentration and the pulse frequency. Administration of orexin-B also significantly reduced the mean LH concentration and the pulse frequency, and coadministration of naloxone did not restore them. These results indicate that orexin-A, but not orexin-B, suppresses GnRH secretion via beta-endorphin.

Animals↗
PubMed1992

Distinct downstream signaling mechanism between erythropoietin receptor and interleukin-2 receptor.

Erythropoietin receptor (EPOR) and interleukin-2 receptor beta chain (IL-2R beta) belong to the same cytokine receptor superfamily and have highly conserved sequences in their intracellular signaling domain. However, common downstream signaling pathways of these receptors have not been demonstrated. In the present study, we introduced and expressed the murine EPOR in murine IL-2-, IL-3- and IL-5-dependent cell lines and analyzed their growth response to EPO. We found that the expression of EPOR induced EPO dependence in IL-3-dependent BAF-B03 and IL-5-dependent Y16 cells but not in IL-2-dependent CTLL-2 cells, although the EPOR-expressing CTLL-2 cell lines could bind and internalize EPO as efficiently as the BAF-B03-derived cell lines. Additional expression of AIC2B, a common signal transducer for IL-3R, IL-5R and GM-CSFR, made no difference to the EPO responsiveness of the EPOR-expressing CTLL-2 cell lines. These results suggest that the cellular components required for the transduction of EPOR signal and IL-2R signal are at least partially different, and this difference cannot be explained solely by the absence of AIC2B.

Animals↗
PubMed1990

Structure of polysaccharide-peptidoglycan complex from the cell wall of Lactobacillus casei YIT9018.

The isolation and analysis of the polysaccharide-peptidoglycan complexes of Lactobacillus casei YIT9018 are presented. Two polysaccharide-peptidoglycan complexes, PS-PG1 and PS-PG2, were solubilized from the heat-killed cell by treatment with N-acetylmuramidase. PS-PG1 was composed of glucose, rhamnose, and small amount of galactose and glucosamine. PS-PG2 was composed of glucose, rhamnose, galactosamine, and glucosamine. The ratio by weight of these fractions was about 1:8. PS-PG2 was analyzed in detail. Smith degradation and deamination of this complex yielded oligosaccharide units. The results of methylation analysis of these units and intact PS-PG2 led to the most probable structure of PS-PG2: (formula; see text)

Carbohydrate Conformation↗
PubMed1990

Increased accumulation of cytosine arabinoside in human leukemic cells and enhancement of its cell-killing activity by uridine.

The effects of uridine(UR) on the cell-killing activity of cytosine arabinoside(ara-C) against human leukemic cells, MOLT-4, and on ara-C accumulation in cells were studied. The 50% lethal dose(LD50) of ara-C as determined by clonogenic assay was decreased to 5.0 x 10(-8) mol from 9.0 x 10(-7) mol after 3 days exposure to 10(-3) mol of UR. The accumulation of 3H-ara-C at 24 and 48 h was significantly increased in culture medium containing 10(-8) mol of 3H-ara-C and 10(-3) mol of UR (5,129 +/- 123.5 vs 2,554 +/- 115.5 cpm/10(5) cells at 24 h, p less than 0.01, and 5,772 +/- 123.2 vs 1,372 +/- 51.8 cpm/10(5) cells at 48 h, p less than 0.01). It is noteworthy that cell-killing activity of ara-C against human leukemic cells was enhanced by the combination with a nucleoside(UR), but not with antileukemic agents.

Cell Survival↗
PubMed1989

[Treatment of acute lymphocytic leukemia in adult].

Since April, 1978 to October, 1988, 66 acute lymphocytic leukemia (ALL) patients aged 15 to 79 (21 L1, 43 L2, 2 L3/6 Ph1+) were treated with 3 different therapeutic protocols. The drugs used for induction were VCR (VDS) + Pred, followed by DNR + VCR (VDS) + 6MP + Pred and VCR (VDS) + L-asp + Pred in protocol I, Ad + VCR + Pred in protocol II and DNR + VCR + Pred in protocol III. Complete remission (CR) was attained in 72.7% of 66 patients. The CR rate of each group as followings; 71.4% in protocol I and 75.0% in protocol II and III, respectively. The median duration of remission was 10.2 months + and the probability of being in continuous CR at 3 years was 21.9%. For the 48 patients in remission the median survival was 17.8 months and the probability of being alive at 3 years was 24.3%. The intensified induction and consolidation therapy is expected in the cure oriented treatment of adult ALL.

Adolescent↗
PubMed1986

Memory changes in the Benton Visual Retention Test between ages 70 and 75.

The influences of education and activity on memory of Japanese older adults were investigated. The Benton Visual Retention Test was given to 302 individuals (145 men and 157 women) aged 69 to 71 (average age 70) living in a suburb of Tokyo. Participants were retested 5 years later (average age 75). Memory as evaluated by Benton correct scores declined in both men and women during the 5 years. The influence of the first time Benton score, education, activity, and sex on the second-time Benton score was analyzed by multiple regression analysis. The second Benton score was strongly influenced by the initial score. Level of education and activity contributed to memory after 5 years. No difference in the magnitude of memory changes was found between men and women. The first time Benton score by education term showed a weak but negative contribution.

Activities of Daily Living↗