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Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 1,027 records · Page 57Linked to original sources
PubMed1983

Immunomodulating activity of thymosin fraction 5 and thymosin alpha 1 in immunosuppressed mice.

We found that both thymosin from calf thymus and its constituent peptide alpha 1 prepared by chemical synthesis restore cell-mediated immunity following its suppression in mice by injection of 5-FU. Conditions suitable for assessing the thymosin activity by means of footpad reaction were established in such immunosuppressed mice. In this new animal model, thymosin alpha 1-peptide showed activity at a low dose of 5-50 micrograms/kg, which was 100-1,000 times less than that required for thymosin F-5 preparations. Further studies utilizing the adoptive transfer technique showed that alpha 1-peptide corrects the 5-FU-induced suppression of mature T cells, transferring the DTH response as well as that of macrophage function responsible for the expression of footpad reaction. Furthermore, regeneration of lymph node and bone marrow cells as well as CFU-c (progenitor cells of macrophages and granulocytes) was enhanced by thymosin alpha 1 in the 5-FU-treated mice. All these results indicate that thymosin alpha 1 accelerates the replenishment and maturation of haematopoietic cells, including not only T cells but also macrophages, when they have been severely damaged by the 5-FU treatment.

Animals↗
PubMed1983

A case report of abetalipoproteinemia (Bassen-Kornzweig syndrome)--the first case in Japan.

The clinical and pathophysiological features of a case of abetalipoproteinemia in a 34-year-old patient are described. This patient is the first case reported in Japan. The patient was diagnosed as abetalipoproteinemia by confirming the Apo-B deficiency in the patient's serum and the slightly high cholesterol level in his mother's and borderline normal level in his father's. The patient had remarkably low lipid levels, acanthocytosis, and lipid malabsorption. An unusual feature of this case was that the patient had no neuromuscular or ocular manifestations. This was possibly related to his normal plasma vitamin A and E levels.

Abetalipoproteinemia↗
PubMed1983

Multiplicity of functional behavior of human intercostal muscles.

Single motor unit activity from the 6th intercostal space in five healthy adults was analyzed during rebreathing, voluntary deep inspiration, Valsalve maneuver and phonation. Action potentials and pneumotach flow were stored on tape and fed to the computer for subsequent analysis. Spike-by-spike analyses revealed three functional types of intercostal motor units. One unit fired almost exclusively during inspiration and its firing was augmented by rebreathing and voluntary deep inspiration (phasic I unit). The second type fired continuously throughout the respiratory cycle with an increase in firing during expiration (tonic E unit); its activity was disrupted during phonation but not during rebreathing, suggesting a postural rather than respiratory function. The third type, silent during quiet breathing, was recruited during rebreathing, voluntary deep inspiration or Valsalve maneuver; its firing started in late inspiration and ceased in early expiration (phase-spanning I-E unit). The relationships between tidal volume and inspiratory time during rebreathing showed that the third type was recruited when tidal volume reached a critical 'volume threshold', suggesting that vagal volume feedback is essential for its activation.

Adult↗
PubMed1983

The regulation of actin polymerization by the 88K protein/actin complex and cytochalasin B.

The action of the 88K protein/actin complex (88K/A) and cytochalasin B on various aspects of actin polymerization kinetics was investigated, and the results were interpreted in terms of the condensation polymerization and treadmilling mechanism for actin polymerization. A substoichiometric concentration of 88K/A promotes actin nucleation under physiological salt conditions, especially in the presence of Ca2+. In addition, it reduces both the elongation rate and the depolymerization rate by up to 70% and inhibits annealing of the actin filaments. As a consequence, the average length of actin filaments polymerized with 88K/A becomes less than that of a control. These data indicate that 88K/A caps one end of actin filaments or actin oligomers where in the absence of 88K/A the rates for both association and dissociation of monomers are faster than at the other end. In a KCl/MgCl2 medium, 88K/A increases the steady state monomer concentration (the critical concentration) to a limited extent. This is explained by assuming that 88K/A caps the lengthening end (in treadmilling) of actin filaments, where the critical concentration is lower than at the other end (the shortening end). Moreover, cytochalasin B which has been shown to bind to the barbed end of actin filaments does not affect the 88K/A-nucleated actin polymerization. Therefore, it is strongly suggested that 88K/A caps the barbed end of actin filaments and that the barbed end is the lengthening end as well as the rapidly growing and rapidly depolymerizing end. The result obtained in the study on the action of cytochalasin B was consistent with this suggestion.

Actins↗