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Biomedical subjects

T Takubo

Publications and source records attributed to T Takubo.

At least 19 recordsLinked to original sources
PubMed1992

A peptidergic component to vagally induced tracheal vasodilation in the dog.

The purpose of the study was to determine the extent that peptidergic afferent and efferent pathways contribute to vagally induced vasodilation in the trachea of the dog. The change in vascular resistance of the tracheal branch of the cranial thyroid artery and the trachealis responses were determined in 28 anesthetized, paralyzed, and mechanically ventilated dogs. After propranolol (2 mg/kg) and phentolamine (1.5 mg/kg), stimulation of the superior laryngeal nerves (NS; 15 Hz, 7 V, 2 ms, 30 s) caused a decrease in vascular resistance of 11.7 +/- 0.8% and a tracheal contraction of 5.2 +/- 4.7 cmH2O. Atropine (1.5 mg/kg) reduced the fall in vascular resistance to 4.7 +/- 0.8% (P less than 0.01), whereas tracheal contraction was abolished. Thiorphan (1.5 mg), a neutral endopeptidase inhibitor, augmented the decrease in vascular resistance (8.8 +/- 0.6%; P less than 0.01) to NS. After hexamethonium (0.5 mg/kg), NS still caused a small decrease in TVR (2.9 +/- 0.9%; P less than 0.05), which was abolished by capsaicin. In atropinized dogs, capsaicin reduced the fall in vascular resistance after NS; the residual vasodilation was virtually abolished by hexamethonium. Acetylcholine (10(-3) mg/kg) decreased vascular resistance (15.7 +/- 3.0%), and the effect was abolished by atropine. We conclude that there is noncholinergic nonadrenergic vagally induced tracheal vasodilation that is peptidergic. The peptidergic vasodilation appears to be mediated by both afferent and efferent pathways.

Acetylcholine↗
PubMed1991

Epithelium modulates the potency of vasoactive intestinal peptide in the guinea pig.

The purpose of the study was to evaluate the importance of the epithelium in determining the potency of exogenous vasoactive intestinal peptide (VIP) in inhibiting responses of isolated guinea pig trachea to vagal stimulation. Isolated innervated tracheal preparations (n = 56) were mounted in glass organ baths in Krebs-Henseleit (K-H) solution at 37 degrees C and gassed with 95% O2-5% CO2. The inside of the trachea was separately perfused with K-H solution at 1 ml/min. The vagal nerve trunks were stimulated (20 V, 1-ms pulses, 10-s trains) at low (0.5 Hz) and high frequency (15 Hz) alternately, and the contractile responses were measured as increases in intratracheal pressures. VIP (10(-8)-10(-7) M) inhibited responses to both high- and low-frequency stimulation. VIP was more potent in inhibiting contractions when administered to the outside than the inside surface of the trachea, and disruptionon of the epithelium abolished this difference. The endopeptidase inhibitors phosphoramidon and thiorphan (5 x 10(-6) M) potentiated the action of VIP. These data indicate that the epithelium reduces the efficacy of VIP. We suggest that the epithelium is a site of degradation of VIP by endopeptidase and may also be a diffusion barrier.

Animals↗
PubMed1991

Ventilatory effects of percutaneous magnetophrenic stimulation.

This study was conducted with the purpose of elucidating the ventilatory effect of percutaneous magnetic stimulation of the phrenic nerve and investigating the possibility of clinically utilizing this effect as the mechanism of an artificial respirator. A magnetic stimulator consisting of a flat circular coil generating strong magnetic fields up to a maximum of 1.3 Tesla was developed. Formed from 1.8 mm diameter copper wire, this coil is 40 mm in diameter, 14 mm in thickness and has an inductance of 24 microH. The appurtenant current generator can deliver more than 5000 A to the coil. The capacitor terminal voltage (Vc) of the generator was used as a parameter of the intensity of the stimulus. Ventilatory effects were assessed mainly by diaphragmatic electromyogram and by transdiaphragmatic pressure, ventilation flow and tidal volume measurements. Magnetic stimulation was applied percutaneously to a unilateral phrenic nerve in dogs as well as human subjects and also to a median nerve of the forearm in human subjects. The range of stimulatory intensity Vc necessary to obtain ventilatory effects was 400-500 V, and the tidal volume thus obtained corresponded to normal breathing at rest for both dogs and humans. No pain was felt in the vicinity of point of application of the stimulator and there were no significant adverse effects such as changes in the ECG or heart rate. These results indicated that percutaneous magnetic stimulation of the phrenic nerve could produce adequate ventilatory effects in control applications.

Animals↗
PubMed1990

Development and clinical application of a portable oxygen concentrator.

We have produced a compact, lightweight oxygen concentrator, using a newly-developed polymer of poly [1-(trimethylsilyl)-1-propyne] with a performance, i.e. oxygen permeability, of 61 x 10 cm3 (STP) cm/cm2 s cmHg, which is 17 times higher than that of the membrane material of conventional concentrators. The oxygen and nitrogen selectivity was 1.80. The dimensions of the apparatus are 325 x 180 x 150 mm and it weighs about 4.0 kg. It is actuated by a battery (DC 12 V, 5.6 Ah), with a 100 V AC source and a car battery (12 V) source also available. The power consumption is 70 W. The generated oxygen concentration is about 30%, and the maximum flow rate is 41/min. Applying 10 samples of various chronic pulmonary diseases to the subject, the suction of oxygen from the apparatus in the patients' rest state was conducted. An increase in the PaO2, from an average of 59.1 Torr before the suction to an average of 68.5 Torr after the suction, together with easing of breathing, was indicated. The usefulness of this apparatus for supplying portable oxygen-treatment to patients with chronic respiratory disease is shown.

Berylliosis↗
PubMed1988

Serum doxapram and respiratory neuromuscular drive in normal man.

To investigate the means by which doxapram affects the control of ventilation, ventilatory function and P0.1 have been related to serum doxapram concentration during a 45-min infusion of doxapram hydrochloride in 7 healthy, conscious subjects under normoxic conditions. Serum doxapram concentrations increased during the infusion: 1.88, 2.48, 3.42, and 3.97 micrograms/ml after 5, 10, 30 and 45 min, respectively. The majority of significant changes in the measurements from the baseline were observed at 30 and 45 min: VE, VT, P0.1, P0.1/end-tidal CO2 tension, VT/Ti and blood pressure were increased, and end-tidal CO2 tension was decreased. No significant changes in Pdimax, Ti/Ttot, VE/P0.1, and P0.1/(VT/Ti) were observed. A correlation was observed between the % increases in P0.1 and VE and doxapram concentration, and between VE and P0.1. The doxapram-induced increase in VE appears to be caused by increased neural drive. It is related to the serum drug concentration in the conscious subject.

Adult↗
PubMed1987

A case of lowered eosinophilic leucocyte peroxidase activity found unexpectedly using an automated haematology analyser (the Technicon H6000 system)

The Technicon H6000 system simultaneously determines blood cell and leucocyte differential counts automatically using cytochemistry and cell size measurements. Part of the information provided by this instrument is a plot of peroxidase staining intensity against leucocyte cell size called 'the leucocyte peroxidase distribution display'. Recently, an abnormal leucocyte peroxidase distribution display was observed, on a sample from a post-operative lung cancer patient, in which eosinophilic leucocytes did not react with peroxidase. Neutrophils reacted in a normal way with this sample. The eosinophils were further examined by electron microscopy and manual peroxidase staining. Some peroxidase positive granules were observed in the eosinophilic leucocytes. The abnormal leucocyte peroxidase distribution display was found to be due to a separate group of eosinophilic leucocytes with lowered peroxidase activity.

Blood Cell Count↗
PubMed1986

Differential count of 5,000 leukocytes for acute nonlymphocytic leukemia patients during remission.

In order to find the level of leukemic cells during remission a differential count of 5,000 leukocytes was made in 91 acute nonlymphocytic leukemia cases during their first complete remission. Patients were divided into three groups according to the level of leukemic cells, i.e., 0-1/5,000, 2-4/5,000 and 5-/5,000. A close correlation was observed between the survival of patients and the level of leukemic cells and their tendency to decrease or increase during remission. All patients in whom leukemic cells rose from 0-1/5,000 to a level higher than 8/5,000 suffered a documented relapse after 4-8 weeks. This method appears to be a good supportive examination for acute leukemia patients during remission.

Acute Disease↗