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T Hiramoto

Publications and source records attributed to T Hiramoto.

At least 55 records · Page 3Linked to original sources
PubMed1984

Genetic activity of bleomycin in Escherichia coli.

The induction of umuC gene expression, cell lethality, induction of W-reactivation of UV-irradiated lambda-phage and the induction of mutagenesis caused by bleomycin (Blm) were studied in Escherichia coli K-12 strains with special references to the effects of SOS repair deficiencies. (1) The umuC gene is inducible by Blm and the induction is regulated by the lexA and recA genes. (2) The lexA and recA mutants are slightly more sensitive to Blm-killing than wild-type strain. (3) The plating efficiency of UV-irradiated lambda-phage increased by Blm treatment of the host cell. This increase was not observed in the umuC mutant. The plating efficiency of UV-irradiated lambda-phage was drastically reduced in the lexA and recA strains treated with Blm. (4) No significant increase of the reversion of nonsense mutation (his-4 to His+) in AB1157 by the treatment of Blm was observed. Possible implications of these results are discussed.

Bacteriophage lambda↗
PubMed1984

Effects of increasing metabolism by 2,4-dinitrophenol on respiration and pulmonary gas exchange in the duck.

The effects of pharmacologically elevated metabolism on respiration and parabronchial gas exchange were studied in the anesthetized, spontaneously breathing duck using 2,4-dinitrophenol (DNP), injected in successive single doses of 1.2-2.5 mg per kg body mass. Oxygen uptake, MO2, increased with the cumulative amount of DNP, reaching a sevenfold resting level at the highest DNP level tolerated, 15 mg/kg. Ventilation increased nearly as much as MO2, mainly by an increase in respiratory frequency, fresp. Cardiac output increased somewhat less than MO2, mediated by increases in both cardiac frequency and stroke volume. Arterial blood-gases showed little change; however, mixed venous PO2 dropped significantly, and PCO2 increased significantly, with stimulated metabolism. Pulmonary diffusing capacity, DO2, showed a significant rise with MO2, beyond that expected from a reduction of functional lung heterogeneity. The results show that pharmacological stimulation of metabolism can evoke responses in the respiratory and circulatory systems that are comparable to those observed with exercise. The mechanism by which parabronchial diffusing capacity increases during elevated metabolism remains to be investigated.

2,4-Dinitrophenol↗
PubMed1982

Reversal of oleic acid-induced respiratory distress by prostacyclin (PGI2).

The effects of Prostacyclin (PGI2) on gas exchange were investigated in 13 adult mongrel dogs with acute pulmonary edema induced by oleic acid (0.09 ml/kg). The time course of changes in gas exchange was measured during spontaneous ventilation with room air. In the Control group, with oleic acid induced respiratory distress, there were marked decreases in arterial PO2 and PCO2, and marked increases in respiratory frequency, expired minute volume, alveolar (end tidal)-arterial PO2 difference, arterial-alveolar (end tidal) PCO2 difference and physiological dead space to tidal volume ratio. In the Test group, respiratory distress was also induced by the oleic acid injection, however, subsequent infusion of PGI2 (200 ng/kg/min) reversed the values of these parameters, which were significantly different from those in the Control group. The results suggest that PGI2 has a protective action against impairment of gas exchange in the presence of increased pulmonary vascular permeability.

Animals↗
PubMed1982

Interactions between lung stretch and PaCO2 in modulating ventilatory activity in dogs.

The effects of changes in airway pressure (Paw) and arterial PCO2 (PaCO2) on ventilatory activity were studied in anesthetized thoracotomized dogs in which both lungs were ventilated separately. Pulmonary artery occlusion on one side and contralateral vagotomy allowed the reflex effects on ventilation of changes in Paw and PaCO2 to be elicited independently of each other. Ventilatory activity was assessed from integrated efferent phrenic activity, analyzed with respect to burst amplitude (Phr), burst frequency (f), and inspiratory TI) and expiratory duration (TE). While Phr increased linearly with PaCO2, it was independent of Paw. Both PaCO2 and Paw affected f in a complex nonadditive way; this response was entirely mediated by effects on TE, TI being unaffected by either stimulus. The analog of ventilation, estimated as Phr x f, increased linearly with PaCO2 and decreased linearly with Paw, but the effects of both stimuli appeared to be additive. It is concluded that the apparently simple effect of Paw and PaCO2 on ventilation results from more complex effects these stimuli exert on its components.

Airway Resistance↗
PubMed1980

Effects of intrapulmonary CO2 and airway pressure on phrenic activity and pulmonary stretch receptor discharge in dogs.

Intrapulmonary CO2 and stretch sensitivity were studied in anesthetized, thoracotomized dogs in which both lungs were independently ventilated. The left pulmonary artery was occluded so that changes in left (Test) lung CO2 did not alter systemic arterial PCO2. Adequate gas exchange was maintained in the right lung, which was vagally denervated. In one series of experiments, neural activity in the C5 root of the phrenic nerve was integrated to assess ventilatory drive at various levels of Test lung CO2 and airway pressure both during cyclic ventilation and static lung inflation. In a second series, single unit activity in vagal afferents from pulmonary stretch receptors (PSR) was recorded. Both phrenic activity and PSR discharge were strongly affected by changes in airway pressure but not by changes in Test lung CO2 between 2 and 7%. However, when test lung CO2 was decreased below 2%, phrenic activity decreased and PSR activity increased. These changes were invariably accompanied by an increase in peak airway pressure during cyclic ventilation suggesting that lung mechanics had been altered. The results indicate that, in this preparation, the effects of lung stretch on ventilatory drive spans a wide range whereas intrapulmonary CO2 exerts an effect only at very low levels. It appears that the reflex effects of both stimuli can be accounted by an effect on PSR activity.

Afferent Pathways↗
PubMed1979

[Gas flow (4)].

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Airway Resistance↗