Search PubMed⌕ Search

Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 883 records · Page 49Linked to original sources
PubMed1981

Relative contributions of chemical and non-chemical drives to the breath-holding time in breath-hold divers (Ama).

Relative contributions of chemical and non-chemical respiratory stimulations to breath-holding time (BHT) were examined in assisted (Funado) and unassisted (Kachido) breath-hold divers (Ama). In the Funado the magnitude of the chemical contribution was reduced, though statistically not significantly. On the other hand, in the Kachido no difference in chemical contribution was seen from the control. This was considered to be due to the fact that ventilatory response to CO2 was reduced in the Funado, but not in the Kachido. Despite the decreased contribution of CO2 drive to BHT, absolute BHT in the Funado was no prolonged. This may be related to sensitization of the respiratory centers to non-chemical stimulation. Such adaptation would be effective for preventing the danger of losing consciousness in the Funado who face extreme hypoxia on returning to the surface from a dive.

Adaptation, Physiological↗
PubMed1981

The ventilatory responses to hypoxia and hypercapnia in the Ama.

The ventilatory responses to hypoxia and hypercapnia of 5 Amas (Kachido) were compared with those of 5 controls of similar ages, physical characteristics and lung volumes. The responses to hypoxia and hypercapnia were analyzed by the equations originally proposed [a] by Lloyd et al. and [b] by Kronenberg et al. as follows: (See the formula in the text) The CO2-response slope in hyperoxia, D, of the Ama (1.820 +/- 0.441 liters . min-1 . Torr-1) was slightly higher than that of the control (1.148 +/- 0.586 liters . min-1 . Torr-1), but the difference was not significant. However, the slope of CO2-response in hypoxia at PETO2 = 44 Torr, S44, was almost the same in the two groups (Ama, 1.822 +/- 0.689 liters . min-1 . Torr-1; control, 1.742 +/- 0.902 liters . min-1 . Torr-1). The ratio of S44 to D was significantly lower (p greater than 0.05) in the Ama (1.039 +/- 0.377) than in the control (1.529 +/- 0.249). Comparing the hypoxic response in terms of the ventilation ratio (VR), the elevation of ventilation with augmentation of hypoxia in the Ama was exceeded by that in the control. Thus, it was suggested that the difference in the ventilatory response to hypoxia between the Ama (Kachido) and the control may have been derived from the respiratory adaptation of the Ama (Kachido) acquired by their daily diving activities.

Adaptation, Physiological↗
PubMed1981

High performance liquid chromatographic determination of aclacinomycin a and its related compounds. II. Reverse phase HPLC determination of aclacinomycin A and its metabolites in biological fluids using fluorescence detection.

A sensitive, simple and selective reverse phase high performance liquid chromatographic method was applied to the determination of aclacinomycin A (ACM) and its metabolites in plasma. The chromatography was performed on a microparticulate phenethyl derivative of silica using a mobile phase of acetonitrile-0.03 M ammonium formate buffer (pH 5.0), (50:50, v/v) and monitoring with fluorescence detector (excitation 435 nm-emission 505 nm). High reproducibility and linear calibration curves were obtained from 20 ng/ml to 100 ng/ml of ACM and its metabolites in plasma by use of internal standard methods.

Aclarubicin↗
PubMed1981

Pancreatic arteriovenous malformation in a patient with gastrointestinal hemorrhage.

A 39-year old woman, with a pancreatic arteriovenous malformation (AVM) which ruptured into the pancreatic duct, was treated successfully with distal pancreatectomy and splenectomy. Histological examinations revealed an AVM with extravasation into the pancreatic ducts. A review of the cases reported to date emphasizes the importance of physical signs, individual histories and angiographic studies for early diagnosis and surgery.

Adult↗
PubMed1981

[Visualization of the false tendon in the left ventricle with echocardiography and its clinical significance (author's transl)].

Echocardiographic features of the false tendon in th left ventricle and its clinical significance were reported. The subjects consisted of 132 consecutive patients, in whom the left ventricle was satisfactorily examined from various aspects with two-dimensional echocardiography. In general, the false tendon was detected in the long axis view of the left ventricle from the apical approach. It was detected in 61 of 132 consecutive patients with echocardiography. The incidence did not seem to be related to the kinds of underlying conditions. The false tendon was usually a string, a few millimeters in width, crossing the ventricular cavity from the vicinity of the papillary muscles to the interventricular septum. In a few patients it looked as Y-figure and net like. Sometimes, several sticks of the false tendon were detected. It was observed to be stretched in diastole and relaxed in systole. On the M-mode echocardiogram the false tendon was displayed as a linear echo moving with heart beat. The false tendon revealed near the interventricular septum, exhibited a motion so similar to that of the interventricular septum that it should be carefully differentiated from the echo of the left ventricular surface of the septum. In 2 patients of valvular heart disease, it was observed to be fluttered in diastole. Echocardiography was more useful in detecting the false tendon than left ventriculography.

Aged↗
PubMed1981

[Mechanism of the systolic anterior motion of the mitral valve and site of the intraventricular pressure gradient in hypertrophic obstructive cardiomyopathy (author's transl)].

The mechanism of the systolic anterior motion (SAM) of the mitral valve and the relationship between SAM and the intraventricular pressure gradient in hypertrophic cardiomyopathy were analyzed. The subjects were 15 cases, in which SAM was observed on the M-mode echocardiograms. Real-time two-dimensional echocardiography was performed at the time of cardiac catheterization and the measurement of left ventricular pressure was made with observing the spatial relationship between the tip of of the catheter and the surrounding intracardiac structures. There were two modes of the systolic anterior motion of the mitral valve in cases with SAM as follows: (1) The hypertrophied papillary muscle protruded into the left ventricular cavity in systole and it caused the displacement of the chordae tendineae, but also the tips of both anterior and posterior mitral leaflets were anterosuperiorly pulled up by the enlarged papillary muscles and the leaflets seemed apparently to intersect the left ventricular outflow tract (type II). These two types seem to make a continuous spectrum. Seven of the 15 cases examined exhibited type I and 8 cases exhibited type II or the intermediate condition. In the cases of type I, the pressure gradient was noted at the level of the tip of the papillary muscles. The inflow tract and the suprapapillary of the outflow tract exhibited a low pressure, while the apical cavity exhibited a high pressure. It is suggested that the enlarged papillary muscles make the ventricular cavity much more narrowly, resulting in the development of pressure gradient at their level. In the cases of type II, the pressure gradient was noted across the anterior and posterior mitral leaflets perpendicular to the outflow tract (subaortic area). The inflow tract exhibited a high pressure in contrast to that in the cases of type I. It is suggested that the anterosuperiorly pulled anterior and posterior leaflets dam up the ventricular cavity, resulting in the development of pressure gradient across them. Here, it should be emphasized that not only the anterior mitral leaflet, but also the posterior leaflet participates to yield the SAM and the intraventricular pressure gradient.

Adult↗
PubMed1981

Effects of 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810) and some antiepileptics on the kindled seizures in the neocortex, hippocampus and amygdala in rats.

Effect of 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810) on kindled seizures in the neocortex, hippocampus and amygdala was studied in comparison with that of clinically proved antiepileptics, and the differences in kindled seizure development in the three areas were also studied. The amygdala more rapidly developed a generalized seizure (kindled seizure) than the hippocampus and the neocortex. Although more days of stimulation were needed, the neocortex also developed a kindled seizure similar to limbic kindled seizures. Phenobarbital, carbamazepine, dipropylacetate and diazepam showed a depressant effect on the neocortical kindled seizures. Phenytoin showed a depressant effect only when it was administered intravenously. Phenobarbital and carbamazepine depressed the hippocampal kindled seizures, while phenytoin and diazepam had little effect. Phenobarbital and diazepam caused marked depression on the amygdaloid kindled seizures, but the effect of phenytoin, carbamazepine and dipropylacetate on them was weak or negligible. AD-810 showed a depressant effect on neocortical and hippocampal kindled seizures, but not on amygdaloid ones. The profile of AD-810 is similar to that seen with carbamazepine.

Amygdala↗
PubMed1981

Evidence for a synergistic interaction between phenytoin and phenobarbital in experimental animals.

Combined anticonvulsant effects of phenytoin and phenobarbital in mice and rabbits were studied using the isobolographic method which was based on the plasma concentrations of these drugs. Anticonvulsant activity of test drugs alone or in combination was determined by the method of maximal electroshock seizure test. Response of each animal to drug action was recorded as abolition of the tonic hindlimb extensor component of maximal electroshock seizure. It was demonstrated that the minimal effective plasma concentrations of phenytoin and phenobarbital alone for protection against maximal electroshock seizure was 5.9 +/- 0.2 and 18.1 +/- 0.4 microgram/ml (+/- SE) in mice and 14.7 +/- 0.5 and 17.5 +/- 0.6 microgram/ml (+/-SE) in rabbits, respectively. Isobolograms for mice and rabbits were constructed by identifying and plotting each responder and nonresponder for its corresponding plasma phenytoin and phenobarbital concentrations when these drugs were given in combination. The isoboles in mice and rabbits were concave bowing toward the origin, indicated synergism (potentiation). The apparent synergism between phenytoin and phenobarbital cannot be explained by changes in the amount of these drugs entering into the brain from the blood, since the relationship between brain and plasma concentrations of either drug was not altered by the presence of the other. These results, therefore, suggest that the synergistic action between these two anticonvulsants occurs within the central nervous system; this provides experimental support for the combined use of phenytoin and phenobarbital in the clinical treatment of epilepsy.

Animals↗
PubMed1981

[Echocardiographic features of the eustachian valve and its clinical significance (author's transl)].

The detailed informations and clinical significance of the Eustachian valve have not yet been elucidated. Real-time two-dimensional echocardiography has enabled one to investigate the Eustachian valve non-invasively. The valve was usually very small. The larger valve was a few cm in length and moved with heart beat. Its motion was analyzed with M-mode echocardiography. In the cases with sinus rhythm, the valve opened gradually in systole, and opened further in rapid filling phase,. followed by the rapid closing at the time of atrial contraction. In the cases of atrial fibrillation with severe tricuspid regurgitation, the valve remained at the semi-closed position throughout systole and opened in rapid filling phase. In one case of tricuspid regurgitation the valve was observed to flutter in systole. After the surgical repair of the tricuspid valve, systolic opening of the valve was noted, though atrial fibrillation persisted.

Adolescent↗