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Biomedical subjects

Y Umegaki

Publications and source records attributed to Y Umegaki.

At least 19 recordsLinked to original sources
PubMed1992

Effect of sleep on binaural interaction in auditory brainstem response and middle latency response.

Binaural interaction (BI) in auditory brainstem response (ABR) and middle latency response (MLR) was measured in 14 adults with normal hearing in the awake and asleep states. The ABR and MLR were recorded with click stimuli given monaurally and binaurally. Four peak-to-peak amplitudes of the response waveforms were measured, and the BI was determined from the amplitude difference between the summed monaural and binaural responses expressed in percent of the summed monaural responses. The magnitude of BI was smallest in ABR (waves I'-V) and largest in the later component of MLR (Pa-Nb) in both the waking and sleeping states. BI values for the peak-to-peak amplitudes in the ABR and MLR were significantly lower (p less than 0.025) in the sleeping state than in the waking state.

Acoustic Stimulation↗
PubMed1991

Effect of sleep on binaural interaction in human auditory evoked potentials.

Binaural interaction (BI) in ABR, MLR and two kinds of 40-Hz steady-state responses (SSRs) were measured in the waking and sleeping states in normal adults. Eleven samples each were collected from 20 subjects. The ABR and MLR were elicited with 500-Hz tone pips. The SSRs were elicited with the same tone pips (pipSSR) or sinusoidally amplitude-modulated tones of the same frequency (samSSR). The amplitude differences between the summed monaural and binaural responses relative to the summed monaural responses were referred to as BI. ANOVA showed that the mean BI in the responses tested was significantly lower (p < 0.005) in the sleeping state than in the waking state. Ad hoc analysis revealed that the significant difference (p < 0.05) in BI between the waking and sleeping states occurred in the pipSSR and samSSR. The BI became larger in the order, ABR, samSSR, pipSSR, MLR, in both the waking and sleeping states. Significant differences (p < 0.05) were detected in the BI during sleep between the MLR and each of the other three responses, whereas in the waking state no significant difference was found between the MLR and tone-pip SSR.

Acoustic Stimulation↗
PubMed1978

Design and development of a comprehensive computer system for radiotherapy departments.

An analysis of computer requirements in radiation therapy departments is presented. The performance and structure of an effective computer system designed for large or small radiotherapy departments are described. The system is composed of two or three sets of minicomputer-based subsystems of which can be operated alone or connected to other subsystems. The size of the system can be adjusted to the size of the radiotherapy department. The system covers treatment planning, automatic control, and record processing.

Computers↗
PubMed1977

Proposed system for ultrafast computed tomography.

Construction of a new ultrafast scanner system suitable for dynamic computed tomography is now under consideration, with development soon to begin. This system will be characterized by an electronically controlled X-ray generator with wide angle double diffraction, which will permit transverse axial images to be taken in times as short as 0.01 second.

Computers↗
PubMed1977

Automated diagnosis of congenital dislocation of the hip.

A study of the automated diagnosis of luxatio coxae congenita (LCC) was performed to establish an automated screening system for hip radiographs. A specific parameter with high diagnostic accuracy was selected by the use of information theory. Pattern recognition programs were written to extract the parameter from digitized hip radiographs. Parameter measurement was performed on 10 radiographs and compared with manual measurements. Results showed good agreement with measurements obtained by specialists. This study confirms the possibilities of automated diagnosis of LCC.

Diagnosis, Computer-Assisted↗
PubMed1977

[Experimental studies on clinical application of 13N-ammonia; a metabolic model and functional image based on animal experiment].

Ammonia has been known to be an inducing agent of hepatic coma associated with liver cirrhosis. In order to establish a non-invasive method of investigating the portal circulation and the metabolism of ammonia at liver the following studies were performed, by using cyclotron produced 13N-labeled ammonia and delayed line-camera interphased with on-line computer system. 1) Animal experiment. Dynamic scintigraphy of thoraco-abdominal region of a rabbit after intrasigmoidal as well as intravenous administration of 13N-ammonia were performed. 2) Theoretical consideration on the functional image of liver: According to the results of the animal experiments, a model of ammonia metabolism having the minimal complexity necessary to represent data in the case of intrasigmoidal administration was proposed. Starting from the solution to the differential equation describing the model, relevant parameters characterizing the dynamic curve of liver were duded.

Ammonia↗
PubMed1977

[Experimental studies on clinical application of 13N-ammonia; clinical application of the functional image].

1) Clinical application: Dynamic scintigraphy of liver and heart of a patient having liver cirrhosis after intrasigmoidal administration of 13N-ammonia (pH 8.1) were performed. Simultaneously, continuous measurments of radioactivity at the left side abdomen and the left temporal region were done by using a scintillation detector for renography. Successive measurement of radioactivity of blood was also carried out. 2) Comstruction of functional images of liver and heart: By using digital radioisotope image of liver and heart of the patient after intrasigmoidal administration of 13N-ammonia, the maps with respect to parameters described in the pervious paper were constructed.

Ammonia↗