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Biomedical subjects

M Okayasu

Publications and source records attributed to M Okayasu.

At least 19 recordsLinked to original sources
PubMed1989

[Role of plasma histamine and neutrophil chemotactic factor in exercise-induced asthma].

The mechanism of exercise-induced asthma (EIA) is still controversial, although the role of chemical mediator is strongly suspected. In the present study, 50 asthmatic patients were observed after exercise on bicycle ergometer during dry air breathing, and changes of plasma histamine and neutrophil chemotactic factor (NCF) were measured and effect of anti-allergic drugs was examined. 31 patients developed postexertional bronchoconstriction and their % reduction of FEV1 after exercise correlated significantly with the degree of airway hyperresponsiveness to inhaled methacholine determined by Astograph. Plasma histamine levels were examined in 20 EIA positive cases and 13 EIA negative cases, but no significant changes were observed between pre- and post-histamine levels in either group. On the other hand, NCF was elevated significantly after exercise in both EIA positive and negative cases, but postexertional NCF levels were significantly higher in EIA positive than in EIA negative cases. The relationship between % increase of NCF and the % reduction of FEV1 after exercise was significant (r = 0.472, p less than 0.05). DSCG and Azelastine protected the development of EIA in 14 out on 19 cases and 7 out of 12 cases, respectively. Pretreatment with DSCG significantly reduced the increase of NCF after exercise. These results indicates that one of the chemical mediator, NCF, may play an important role in producing postexertional bronchoconstriction in asthmatic patients.

Adolescent↗
PubMed1988

Airway hyperresponsiveness after endotoxin inhalation depends on leukocyte infiltration.

We have investigated the relationship between acute airway hyperresponsiveness and polymorphonuclear cell (PMN) migration in airways following saline or endotoxin (ET) aerosol inhalation in 63 guinea pigs. In 20 of these animals, granulocytopenia was induced by prior treatment with hydroxyurea (HU). Airway responsiveness (AR) to inhaled methacholine, together with leukocyte counts in bronchoalveolar lavage fluid (BALF) and in tracheal epithelium, was also examined before and at 30 min, 1, 3 and 6 hr after saline or ET inhalation. In saline inhalation groups, AR and PMN counts in BALF and in tracheal epithelium did not differ from control animals at any time points. However, in ET inhalation groups AR increased significantly at 1 and 3 hr and returned to the pre-exposure level at 6 hr. This period of hyperresponsiveness was associated with an increment of PMN migration into tracheal epithelium. However, the increment of PMN counts in BALF was delayed to 3 and 6 hr after ET. In HU treated animals, AR and PMN counts in BALF and in tracheal epithelium did not change during 6 hr after ET inhalation. These results suggest that the hyperresponsiveness induced by ET inhalation either depends upon PMN migration into the tracheal epithelium.

Administration, Inhalation↗
PubMed1987

Temperature affects lung fluid and recoil during high tidal ventilation at low resting volume.

Effects of tidal volume (VT), end-expiratory pressure (EEP), and environmental temperature (Tenv) on elastic recoil force (Pel) and edema formation were examined in open-chest anesthetized rabbits. Sixty-two rabbits in four groups were ventilated for 3 h with VT of either 10 or 25 ml/kg body wt, EEP of 0 or 2 cmH2O, and Tenv of 18 or 35 degrees C. After ventilation, Pel at 80% of total lung capacity (P80) was significantly increased when ventilation was performed with the combination of large VT, 0 EEP, and low Tenv. This change was prevented by altering any one of the three conditions, e.g., small VT, positive EEP, or high Tenv. Similarly, elevation of minimum surface tension and reduction of surface activity index of lavages from excised lungs after ventilation were observed only when increased P80 was noted. Additionally, the increase of P80 was well correlated with increment of wet weight-to-dry weight ratio and degree of perivascular cuffing and alveolar edema formation of excised lungs. These results indicate that elevation of Pel after high tidal ventilation in open-chest animals in vivo was influenced by level of EEP and Tenv and that the degree of edema formation was closely related to the increase of Pel. The increased Pel is presumably primary and causes fluid accumulation.

Animals↗
PubMed1985

[In vitro sensitivity test of anti-neoplastic agents and their enhancement by biscoclaurine alkaloid].

UNLABELLED: We tried an in vitro sensitivity test for the purpose of examining the effect of anti-neoplastic agents and their enhancement by Biscolaurine Alkaloid (Cepharanthin). Methods, HeLa cells were synchronized by excess of thymidine and hydroxyurea, and resuspended in Eagle's MEM with 10% FCS. The cells were mixed with Mitomycin C or Bleomycin and added to the wells of a microtiter plate. When required, Cepharanthin (the effect of this drug is considered to change the plasma membrane liquidity) was added to the medium, and then cultured for 24 hours in a CO2 incubator. After culture, each well received 3H-thymidine, and was incubated for 8 hours. The cells were harvested for the assay of 3H-thymidine. RESULTS: MMC or BLM suppressed the uptake of 3H-thymidine in relation to its concentration. MMC or BLM with various concentrations of Cepharanthin showed strong suppression compared with the same concentrations of MMC or BLM alone. From the above results, this experimental method is regarded as an useful model for selecting sensitive anti-neoplastic agents. In addition, Cepharanthin showed enhancing effects on anti-neoplastic agents.

Alkaloids↗