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Biomedical subjects

F Hayashi

Publications and source records attributed to F Hayashi.

At least 181 records · Page 10Linked to original sources
PubMed1983

The effect of isobutylmethylxanthine on the photoresponse and phosphorylation of phosphatidylinositol in octopus retina.

The effect of isobutylmethylxanthine on the photoresponse and the phosphorylation of phosphatidylinositol was studied. The recovery of photoresponse after a bright flash was greatly altered by the addition of isobutylmethylxanthine. Phosphatidylinositol phosphorylation, assessed by the incorporation of label from [gamma-32P]ATP, was influenced by isobutylmethylxanthine. Incorporation of 32P was decreased into diphosphoinositide and triphosphoinositide, and increased into phosphatidic acid. These changes were interpreted by introducing a parameter, phi, calcium charge of the plasma membrane.

1-Methyl-3-isobutylxanthine↗
PubMed1983

The ventilatory response to hypoxia in the anesthetized rat.

The hypoxic ventilatory response of the anesthetized rat was measured using a progressive hypoxia test whilst end-tidal Pco2 was maintained at a constant level. The ventilatory response to hypoxia was expressed by the equation, VE = Vo + A/(Pao2-C)(VE, total ventilation in l BTPS . min-1; Pao2, arterial Po2 in mm Hg). The hypoxic ventilatory drive, A, averaged 4.1 +/- 2.5 1 . min-1 . mm Hg (mean +/- SD), from which a value of 252 1 . min-1 . mm Hg was calculated on the basis of appropriate allometric relationships, for a 70 kg body mass. This value is higher than those reported for the anesthetized dog and for human subjects. When end-tidal Po2 was gradually decreased from hyperoxia to normoxia, a significant increased in VE due to an increase in breathing frequency was observed, suggesting that the ventilation of the rat is maintained by a considerable 'hypoxic drive' even in normoxia. Furthermore, hypoxic ventilatory depression occurred at a relatively higher Pao2 level (45-60 mm Hg) than in other species. Thus, in the rat, the ventilation vs. end-tidal Po2 curve is shifted to the right compared to other species. After section of the carotid sinus nerve, the hypoxic drive (A) was reduced to 11%, indicating that almost all the ventilatory drive of hypoxia was mediated by the carotid chemoreceptors.

Anesthesia, General↗
PubMed1983

Overall "gain" of the respiratory control system in normoxic humans awake and asleep.

With the addition of external dead space in normoxia, PCO2-ventilation response and CO2 production were determined in 10 healthy male subjects. Overall "gain" (G) of the respiratory control system was calculated from the slope of the CO2-response curve (S) and that of the metabolic hyperbola (SL) at alveolar partial pressure of CO2 (PACO2) of the respective experimental run. We found that 1) despite the depression of ventilation during non-rapid-eye-movement (NREM) sleep, G was generally not changed due to decreased SL, although considerable individual variations were seen; 2) effects of external dead space on PACO2 change during sleep and wakefulness were similar in magnitude; and 3) the above PACO2 changes experimentally induced agreed well with the predicted values estimated from G. Contrary to general opinion, these results demonstrated that overall gain of the respiratory control system is generally not depressed during NREM sleep in normal healthy subjects.

Adult↗
PubMed1983

An assessment of overall "gain" of the O2-feedback control system with and without external dead space breathing.

Overall gain of the O2-ventilation feedback control system (GO2) was determined in 9 male and one female healthy subjects. GO2 progressively increased with decreasing end-tidal PO2 (PETO2). This value did not exceed the overall gain of the CO2-ventilation feedback system (GCO2) even at a PETO2 level of 40 mmHg, suggesting that hypoxic stimulation did not become predominant in the present experimental condition. With addition of 250 ml of external dead space, PETO2 decrement (delta PETO2 X actual) was experimentally observed. The delta PETO2 X actual thus obtained was found to be in good agreement with the PETO2 decrement deduced from GO2 (delta PETO2 X expected). This result was similar to that found in the PETCO2 change previously seen in normoxia.

Adult↗
PubMed1982

CO2-ventilatory response of the anesthetized rat by rebreathing technique.

The ventilatory response to CO2 in rats under sodium pentobarbital anesthesia has been measured using the rebreathing technique. The animal rebreathed through a tracheal cannula for a period of 4 min from an apparatus of 200-400 ml capacity, containing 5-6% CO2 in O2. Pco2 in the rebreathing apparatus (PappCO2), instantaneously Vt, f, and Ve were monitored before, during, and after rebreathing. During the rebreathing run, PappCO2 and Paco2 rose linearly from 35-40 to 65-70 mm Hg; there was no significant difference between PappCO2 and Paco2 at any time during rebreathing. Vt and Ve increases almost linearly with the rise of PappCO2, while f increased to a maximum within 2 min of rebreathing. In the rat, Vt regulation seemed to operate exclusively as a proportional control system in response to linearly increasing CO2 stimulus. The slopes of PappCO2, Vt or Ve response curves varied considerably during the time course of the experiment, depending upon the level of anesthesia, even though there was no large change in Ve in the control periods which were under hyperoxic conditions. However, a significant linear relationship was seen between f in the respective control period and the slope of PappCO2-Vt response at various levels of anesthesia. We concluded that the rebreathing technique can be applied in small experimental animals and that changes in the sensitivity of the respiratory control system to a CO2 stimulus by anesthesia can be easily monitored by repeating the rebreathing test.

Anesthesia, General↗
PubMed1982

Conjugation of drug-resistance plasmids from vibrio anguillarum to Vibrio parahaemolyticus.

Drug-resistant strains of Vibrio anguillarum, a fish pathogen, were isolated from diseased fish in culture ponds. In investigations of these strains, the transfer of resistance to chloramphenicol, tetracycline, and sulfanilamide from multiple resistant organisms to laboratory recipients was observed. The plasmid from V. anguillarum was stably maintained in both recipient strains of Vibrio parahaemolyticus and Escherichia coli. The plasmids isolated from Vibrio anguillarum belong to incompatibility group C. The molecular weight of these plasmids determined by electron microscopic observation was about 103 to 113 megadaltons.

Chloramphenicol↗
PubMed1982

Ventilatory response and drive due to carbon dioxide stimulation in idiopathic scoliosis.

Ten patients with idiopathic scoliosis and seven controls were studied for the purpose of investigating the ventilatory response and drive due to CO2 inhalation by the steady state CO2 response test. To evaluate the ventilatory drive for the respiratory output mouth occlusion pressure (P0.1) was used. The ventilatory response to CO2 of the patients was not significantly different from that of the controls. P0.1 for a given PCO2 stimulation or tidal volume in the patients was significantly higher than the control. Ventilatory output against P0.1, however, was not different in the two groups. The small tidal volume of the scoliotic patients seemed to be compensated by the high respiratory frequency with a large ventilatory drive in order to maintain adequate ventilation.

Adolescent↗
PubMed1982

Attenuated ventilatory responses to hypercapnia and hypoxia in assisted breath-hold drivers (Funado).

The steady-state ventilatory responses to hypercapnia and hypoxia in 7 assisted breath-hold divers (Funado) were compared with those in 7 normal sedentary controls. Ventilatory response to hypercapnia was measured from the slope of the hyperoxic VN-PETCO2 line, where VN was normalized minute ventilation using the allometric coefficient and PETCO2 end-Tidal PCO2. The slope of this line in the Funado (1.48 +/- 0.54 liters . min-1 . Torr-1) was significantly less than in the control (2.70 +/- 1.08 liters . min-1 . Torr-1) (p less than 0.025). On the other hand, hypoxic sensitivity estimated by hyperbolic and exponential mathematical equations was not found to be significantly different between the two groups, although estimated increments in ventilation using the hyperbolic equation exhibited significantly lower response in the Funado than in the control only when PETO2 decreased lower than 50 Torr (p less than 0.05). These findings in the Funado were different from our previous observations obtained in unassisted breath-hold divers (Kachido), in whom no obvious attenuations in CO2 sensitivity were seen. This difference was assumed to be derived from more hypercapnic and hypoxic conditions produced in the Funado than in the Kachido during diving activities.

Adult↗
PubMed1982

Ventilatory response to CO2 after brief stimulations of the peripheral chemoreceptors in man.

Whether or not stimulation of the peripheral chemoreceptors by hypercapnic-hypoxic exposure results in a long-lasting increase in ventilatory activities was studied using the steady state CO2 response test on 12 human subjects. The degree of hypercapnic hypoxia was end-tidal PCO2 (PETCO2) 42.1 +/- 3.0 and PO2 (PETO2) 39.8 +/- 4.7 mmHg, lasting for 5 min. Minute ventilation values at PETCO2 45 mmHg (V45) and PETCO2 at minute volume 15 liter . min-1 (P15) were calculated from the respective CO2 response curves. The differences in V45 and P15 between the control and the 30 min test group were found to be significant (p less than 0.05). These results suggested the left- and upward-shift of the CO2 response curve of the 30 min test group. On the other hand, in 5 of the 12 subjects, three successive CO2 response tests conducted at 0, 30, and 90 min without hypercapnic-hypoxic exposure showed fairly reproducible results, and no statistically significant differences were found between any of the above trials with the parameters S, B, V45, and P15. These results indicated that the CO2 response curve obtained by using the steady state method can be effected for at least 30 min even if the stimulation of the peripheral chemoreceptors is only for brief periods.

Adolescent↗
PubMed1982

High ventilatory response to hypoxia observed in obese Judo athletes.

Fifty-two active Judo athletes were examined using an isocapnic progressive hypoxia test. The results were analyzed by the hyperbola ventilation equation V = VO + A/(PETO2--C), where V is observed ventilation, VO the horizontal asymptote in ventilation for infinite end-tidal PO2(PETO2), A the slope constant indicating magnitude of hypoxic sensitivity, and C the vertical asymptote in PETO2 for infinite ventilation. Hypoxic sensitivity, A, was positively correlated with body weight (BW). Such correlation in the light and middleweight groups (BW less than 95 kg) and the heavyweight group (BW greater than 95 kg) with Röhrer's index being less than 200 became insignificant when the A value was recalculated after normalization of ventilation for 70 kg body mass. However, the heavyweight group with Röhrer index of higher than 200 still exhibited a significantly higher A value than the light and middleweight groups after normalization of ventilation. These results indicated that body weight plus obesity were determining factors in the increase of hypoxic sensitivity in our subjects.

Adolescent↗
PubMed1981

Analysis of pressure profile in the occluded airway obtained at the beginning of inspiration in steady state hypercapnia.

Using the steady state CO2 response test, we measured inspiratory mouth occlusion pressure and ventilatory volume in 38 normal subjects. At each degree of hypercapnia, 5 occlusion trials were performed. Occlusion pressure (Pt) and the timed differentials (dp/dtt) measured at 0.025-s intervals from the onset of inspiration until 0.2 s, dp/dt at 1 cmH2O pressure (dp/dt1 cmH2O), and peak dp/dt (dp/dtpeak) were determined. To evaluate the usefulness of these indexes, coefficients of variation and correlation coefficients with VT, normalized VE (VN), PACO, and inspiratory flow without occlusion were calculated. Coefficients of variation in Pt decreased with time from the onset of inspiration, being lowest at P.2. In contrast, those for dp/dtt were lowest at 0.075 sec, and thereafter rapidly increased. Correlation coefficients between Pt and respiratory parameters were high (0.94 to 0.98) for most times except at the very beginning of inspiration. Those between dp/dt and respiratory parameters were somewhat lower (0.91 to 0.97). Correlation of tidal volume with occlusion pressure was poor, thus the occlusion analysis was considered inappropriate to evaluate tidal volume output.

Adolescent↗