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Biomedical subjects

O Yamada

Publications and source records attributed to O Yamada.

At least 289 records · Page 16Linked to original sources
PubMed1977

The effect of onset, offset and rise-decay times of tone bursts on brain stem response.

Auditory-evoked brain stem responses (BSRs) were recorded from the scalp in 4 cats and 10 human subjects. Auditory stimuli consisted of 1 kHz tone bursts and their duration, intensity and rise--decay time were varied. The BSR evoked by the tone bursts consisted of on- and off-responses. The off-responses showed different intensity--amplitude and different intensity--latency functions from the on-responses. In the feline subjects, an increase in rise time as an input resulted in an increase in the number of recorded sharp waves of the on-responses, indicating that several cycles of tone bursts during the rise time take part in generating on-responses. In both the feline and human subjects, BSRs were evoked by tone bursts with a rise time of as long as 10 msec; an increase in the rise time resulted in an increased latency and broadened waveforms of the on-responses. These demonstrated properties of BSR may provide useful information in determining input parameters, such as rise--decay time, appropriate for audiometric assessment.

Acoustic Stimulation↗
PubMed1976

[Traumatic aneurysm of the peripheral cerebral artery].

Two cases of traumatic aneurysm of peripheral cerebral artery were reported. Case 1. A 6-year-old girl was severely injured on her head by automobile accident. Plain skull films showed depressed fracture in the left frontal region. Left common carotid angiogram 25 days after the injury revealed small aneurysm of a cortical branch of the anterior cerebral artery. Cranioplasty and removal of the aneurysm was performed. Postoperative course of this patient was uneventful. Case 2. A 4-year-old girl fell downstaris and struck her left temporal region. On admission, she was unconscious and plain skull films showed multiple linear fractures. No aneurysm was demonstrated in the right common carotid angiogram immediately after the head trauma. Since her general condition gradually improved, she discharged 23 days after the head trauma. 63 days after the injury, she developed sudden onset of severe headache, vomiting, and status epilepticus. Right common carotid angiogram showed a large aneurysm arising from a branch of right pericallosal artery at the free edge of the falx. Parent artery of the aneurysm was clipped. Postoperatively, the patient made uneventful recovery. 60 reported cases of traumatic aneurysm of peripheral cerebral artery were reviewed and analyzed in etiology, diagnosis, clinical course, treatment and pathogenesis.

Brain Injuries↗
PubMedDate not supplied

Longitudinal observations of left ventricular end-diastolic dimension in children using echocardiography.

Previous studies have evaluated left ventricular dimensions in children using two-dimensional echocardiography, but there is little information on gender differences and on the longitudinal development of the dimensions of the left ventricle. Our objective was to assess, by two-dimensional echocardiography, the normal size of the left ventricular end-diastolic dimension (LVDd) in children, its differences by sex, and the rate of its development using height, weight, and body surface area as indices. The study group consisted of 437 patients (264 males, 173 females) with a history of Kawasaki disease but with no coronary artery lesions, as determined by repeated echocardiographic and other examinations. A total of 1595 examinations were done over an average of 6.7 years. The increase in LVDd was significantly more rapid in (1) children below 2 years of age than in older children of either sex and (2) in males who were 11 and 12 years old than in males who were 10 years old. Significant gender differences were observed in the increase in LVDd by all indices (p < 0.001).

Adolescent↗
PubMedDate not supplied

The relation between right ventricular function and left ventricular morphology in hypoplastic left heart syndrome: angiographic and pathological studies.

Cases of hypoplastic left heart syndrome (HLHS) were studied angiographically in 18 patients and pathologically in 22 patients. They were divided into three subgroups according to the morphological features of the left heart: mitral atresia with aortic atresia (MA/AA), mitral stenosis with aortic atresia (MS/AA) and mitral stenosis with severe aortic stenosis (MS/AS). Patients with MS/AA had a significantly lower right ventricular end-diastolic volume index and more hypokinesis of the right ventricular posterior wall than those with MA/AA. MS/AA not only increased the thickness of the left ventricular posterior wall and interventricular septum but also increased endocardial thickness compared with MA/AA. Myocardial histology revealed more frequent abnormal findings such as myocardial necrosis, calcification and interstitial fibrosis in the mitral stenosis groups (i.e., MS/AA and MS/AS) than in MA/AA. Right ventricular function appeared to be greatly influenced by left heart structure. The presence of larger left ventricular muscle bulk and frequent myocardial damage seen in MS/AA seems disadvantageous to right ventricular end-diastolic volume and right ventricular wall motion.

Analysis of Variance↗