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Biomedical subjects

T Inouye

Publications and source records attributed to T Inouye.

At least 37 records · Page 2Linked to original sources
PubMed1995

Potential flow of alpha activity in the human electroencephalogram.

The movement of potential field of alpha activity was investigated with a potential flow technique, alpha activity was divided into slow, medium and fast subbands. The peak-to-peak amplitude and source density distribution of each subband was also constructed. The potential flow of medium alpha was from medial to lateral in the anterior region, and from lateral to medial in the posterior region. The flow patterns of slow and fast alpha were more complicated. Similar flow directions formed a group. Different groups met or diverged at discontinuous grid points around the local maxima of potential distribution. The discontinuous points of medium alpha were centered in the parieto-occipital region, and those of slow and fast alpha were more equally distributed over the scalp. Against potential gradients, several groups of similar flow directions participated in the formation of potential field. The generation of potential field was assumed to be controlled widely for medium alpha and locally for slow and fast alpha.

Adult↗
PubMed1995

A new segmentation method of electroencephalograms by use of Akaike's information criterion.

Non-stationary EEGs, whose statistical properties change with time, were segmented into stationary segments to closely track the behavior of EEG characteristics. We have developed a new segmentation method of optimizing segmentation parameters by using AIC (Akaike's information criterion) as an objective criterion. We applied the segmentation method to EEGs. The instantaneous power spectra of EEGs estimated with wavelet transform were compared with the segmented EEGs. EEGs were recorded from F3, F4, C3, C4, P3, P4, 01 and 02 in 13 normal subjects. Artifact-free 15-s epochs were taken at each electrode location. Each epoch was divided into stationary segments, consisting of several fixed intervals, by optimizing 2 segmentation parameters (interval length and starting point) so that the sum of AICs for several sequences of segments could be the smallest. The EEG segmentation could represent differences in the power spectra between segments. The average length of segments during relaxed wakefulness was 6.0 +/- 3.8 s. The EEG segmentation during mental arithmetic could detect the start of mental arithmetic.

Adolescent↗
PubMed1995

Inter-site EEG relationships before widespread epileptiform discharges.

EEG interactions of the background among locations can start to change just before epileptiform discharges. Such interactions were investigated with relative power contribution analysis based on a multivariate autoregressive model, which permits determination of multiple causal relations of EEGs among locations. EEGs from F3, F4, P3, P4, T3 and T4 were examined in 10 epileptic patients with asymmetric spike and wave complexes (SWCs). A 12.5-s epoch just before SWCs was divided into stationary segments throughout 6 locations with a segmentation method. In segments long before SWCs, most power at each location was generated from its own location. In segments immediately preceding SWCs, contributions from other locations, particularly from the hemisphere with smaller SWCs, increased. Overall EEG relationships among 6 locations were examined by an entropy which measures the uniformness of the spatial distribution of power contribution. The entropy significantly increased gradually toward SWCs. Our findings demonstrated stronger interactions among locations just before epileptiform discharges, suggesting a transitional state from background EEG to epileptiform discharges.

Adolescent↗
PubMed1995

[Effects of transcutaneous silicon injection for aspiration caused by unilateral vocal cord paralysis].

The purpose of this study was to determine the effects of transcutaneous silicon injection on swallowing function in unilateral vocal cord paralysis with aspiration. The preoperative and postoperative swallowing function were evaluated by means of videofluoroscopy and pharyngeal manometry in eight patients who received injection of silicon into the laryngeal vestibule, ventricle and vocal cord. Data analysis compared 1) types of aspiration and pharyngeal clearance, 2) timing of laryngeal closure (complete closure between arytenoid and epiglottic base) that was correlated with the onset of cricopharyngeal (CP) opening as time zero, and 3) swallowing pressure in the pyriform sinus on the side of the paralyzed vocal cord. In seven of the 8 patients, a favorable clinical response was achieved and aspiration and/or penetration were not observed on the fluoroscopic images after the silicon injection. Timing of laryngeal closure could be quantified in six patients, and mean values of the times preceding the onset of CP opening were significantly earlier on the postoperative examinations than preoperative examinations. Pharyngeal clearance on the affected vocal cord side was improved in six of the 8 patients, and swallowing pressure in the pyriform sinus was significantly elevated in four patients following surgery. These results suggested that silicon injection therapy produced earlier laryngeal closure during the swallow and improvement of pharyngeal clearance on the affected side after the swallow, so that aspiration and/or penetration with vocal cord paralysis might be prevented.

Aged↗
PubMed1994

Changes in the fractal dimension of alpha envelope from wakefulness to drowsiness in the human electroencephalogram.

Changes in the fractal dimension of the waxing and waning of alpha activity from wakefulness to drowsiness were investigated in 10 normal subjects. The envelope of filtered alpha activity was estimated with the Hilbert transform. A subset time series was constructed from the alpha envelope data taken at an interval (k). The points of the logarithm of interval k vs. the logarithm of the curve length of the subset time series (log L(k)) were fitted by a two-segment curve, consisting of small and long line segments (segments 1 and 2). The fractal dimension was estimated from the slope of straight line for each segment by using Higuchi's method. The mean fractal dimension was 1.16 for segment 1 and 1.95 for segment 2 during wakefulness and 1.15 for segment 1 and 1.89 for segment 2 during drowsiness. The fractal dimension significantly decreased in both segments during drowsiness, thus, indicating decreases in the complexity of alpha envelope.

Adult↗
PubMed1994

Increases in the power spectral slope of background electroencephalogram just prior to asymmetric spike and wave complexes in epileptic patients.

Moment-to-moment electroencephalogram (EEG) changes just before spike and wave complexes (SWCs) were investigated by using a non-stationary power spectral analysis in 10 epileptic patients with asymmetric SWCs. The instantaneous power spectra of background EEG were estimated for a 10-s period just before SWCs in 10 locations. The spectral shape, showing a l/f amplitude characteristic, was assessed by the negative slope (spectral slope) of a straight line on a plot of log power versus frequency. Spectral slope significantly increased toward SWCs at locations with greater SWCs. This finding suggested structural changes in EEG frequency composition just before SWCs because of an epileptogenic process.

Adolescent↗
PubMed1994

Potential flow of frontal midline theta activity during a mental task in the human electroencephalogram.

The movement of potential field (potential flow) of frontal midline theta activity (Fm theta) as well as its potential distribution was examined in 7 subjects by using optical flow detection techniques in image processing. Electroencephalograms (EEGs) over the fronto-central region were recorded from 13 electrodes near the frontal midline (Fz) while the subjects were performing a mental task. The potential flow of Fm theta was estimated on a frame consisting of a square grid with Fz at its center. In regions anterior to Fz, the direction of potential flow was from lateral to medial, whereas it was from medial to lateral in regions posterior to Fz. The peak-to-trough amplitude distribution was round or oval with a maximum just anterior to Fz. The source density distribution showed the greatest potential along the midline in the frontal region and bilaterally symmetric smaller maximum areas mostly in the prefrontal regions. Our findings suggested the presence of 2 different source areas of opposite direction in each hemisphere in spite of a round or oval amplitude distribution.

Brain Mapping↗
PubMed1994

Moving potential field of frontal midline theta activity during a mental task.

The movement of potential field (potential flow) of frontal midline theta activity (Fm theta) was examined by using optical flow detection techniques in image processing in 6 normal subjects. Electroencephalograms (EEGs) over the fronto-central region were recorded from 13 electrodes around Fz. The potential flow of Fm theta was estimated on a frame which consisted of a square grid of 19 x 19 points in which each of the 13 electrodes was positioned with Fz at the center of grid. The peak-to-trough amplitude distribution was rounded or oval with a maximum just anterior to Fz. In each hemisphere, potential field moved medially in a region anterior to Fz, posteriorly near or at the midline and laterally in a region posterior to Fz. In the temporal sequence of potential field, at each point velocity directions tended to change progressively clockwise or counterclockwise. In the whole frame, a rotary movement of potential flow was found with a center at the middle on each side. Our findings suggested that a potential maximum at the midline may be due to overlapping of fields of opposite direction over the frontal scalp, arising from sources of similar orientation in both hemispheres. It can be assumed that Fm theta propagates in a clockwise direction in the left hemisphere and in a counterclockwise direction in the right hemisphere.

Adolescent↗
PubMed1994

Endoscopic laser surgery for subglottic and tracheal stenosis.

Seventeen patients with subglottic and tracheal stenosis were treated with laser surgery. Six patients had airway stenosis caused by malignant tumors. Out of 16 patients who required emergency endolaryngeal laser surgery, satisfactory results were achieved in 12, obtaining a sufficient lumen for ventilation. Five cases with airway tumors underwent laser surgery to increase the airway lumen, however, only one patient showed excellent results, with a sufficient airway lumen not being obtained in the others. Airway obstructions due to tumor can be treated satisfactorily by laser surgery, though long-term postoperative follow-up confirmed recurrence of tumor in some cases, which is a problem that must be overcome in the future.

Head and Neck Neoplasms↗
PubMed1993

Localization of activated areas and directional EEG patterns during mental arithmetic.

In a search for the physiological correlates of mental activity, localized EEG desynchronization induced by mental arithmetic was assessed by the entropy of the EEG power spectrum (irregularity index II). The topographic mapping of II can show a localized cortical activation. Directional EEG patterns during mental arithmetic were further examined with a directed mutual information measure (information flow). These two information measures were compared between resting and mental arithmetic conditions in 10 right-handed subjects as well as one left-handed subject. II significantly increased during mental arithmetic in the left temporo-centro-parietal region in right-handed subjects, thus exhibiting its activation. Significant changes in information flow during mental arithmetic were found in the directions mostly from the temporo-centro-parietal region to other areas and within the frontal region in right-handed subjects: information flow from the left temporal and the mid-frontal areas increased and information flow mostly from the left hemisphere decreased. One left-handed subject showed greater II in right post-temporal area. These findings suggest that the left temporo-centro-parietal activation is specific to calculation processing, and the frontal information flow is related to the active performance of mental arithmetic.

Adolescent↗
PubMed1993

Laryngeal closure at the level of the false cord for the treatment of aspiration.

A new procedure for aspiration which closes the larynx at the level of the false cords is reported. This method is not harmful to the vocal folds and maintains arytenoid movement, thus preserving phonatory function. With the advance of the operative technique for aspiration and swallowing rehabilitation, patients who have recovered from aspiration can be helped. Our procedure can be recommended for such cases.

Aged↗
PubMed1993

Distinctive increases in HLA-DR+ and CD8+57+ lymphocyte subsets in Wegener's granulomatosis.

Lymphocyte subset abnormalities have been observed in a series of patients diagnosed with Wegener's granulomatosis (WG). Fifteen patients with WG were evaluated for lymphocyte subset abnormalities by two-color immunofluorescence flow cytometry. The WG group showed a decrease in CD4+ cells and an extraordinary increase in HLA-DR+ cells. The average percentages of HLA-DR+ cells of the normal group and WG group were 11.0 +/- 4.0 and 40.5 +/- 13.9% (CD3+HLA-DR+ = 20.3 + 9.4%). Within the CD8 family, CD8+57+, CD8+38+ and CD8+HLA-DR+ cells were markedly elevated. Our findings differ from other series which reported that the lymphocyte subsets in the peripheral blood of patients with WG were normal.

Adult↗
PubMed1993

Preservation of alpha rhythm shortly after photic driving.

EEG responsiveness to intermittent photic stimulation (IPS) with repetitive flashes was examined just after the pause of IPS. By omitting 5, 10, 15 and 20 flashes in the course of IPS at 10 Hz, 2 s IPS responses at the midline occipital area were compared between flash trains before (train 1) and after the pause (train 2). Amplitude, peak frequency and bandwidth (reflecting the degree of rhythmicity) of an alpha peak in the power spectrum of averaged IPS responses were each obtained every 50 ms with the power spectrum based on a time-varying AR model. Bandwidth was more sensitive to IPS responses, because significant differences in bandwidth between trains 1 and 2 occurred earlier than differences in amplitude. There were greater differences in bandwidth for the omission of 5, 10 and 15 flashes, suggesting increased responsiveness to train 2, while there were no significant differences in bandwidth for the omission of 20 flashes. These findings show that rhythmicity in IPS responses can be preserved up to 1.6 s after the pause of IPS.

Adult↗
PubMed1993

[Relationship between cervical osteophytes and globus sensation--a study based on altered swallowing function].

The swallowing function of ten patients showing marked cervical osteophytes were studied by double contrast pharyngogram and manometric examinations. In five cases in which the pharyngeal clearance was B type according to Shuzaki's classification, a significant increase in the maximal swallowing pressure value on the oral side ipsilateral to the osteophytes was often observed. In five cases in which the pharyngeal clearance showed A + A' type (marked impairment), the frequency of significantly decreased maximal swallowing pressure on the oral side ipsilateral to the osteophytes and abnormal waveforms of the swallowing pressure were high. However, no definite correlation was noted between these changes in swallowing function and osteophyte site. Therefore, there are two possible outcomes of the changes in swallowing function caused by cervical osteophytes: one is a compensatory increase in pharyngeal constriction aimed at maintaining relatively good pharyngeal clearance, the other is impaired pharyngeal constriction and the pharyngeal clearance. These changes in swallowing function would impact on globus sensation.

Aged↗
PubMed1992

Half-field sinusoidally modulated light stimulation at subject's alpha frequency.

Interhemispheric responses of alpha activity were investigated by use of half-field sinusoidally modulated light (SML) stimulation at the subject's alpha frequency. The left and right visual half-fields as well as full-field were separately stimulated by the SML. The power spectrum of SML responses, averaged with Wiener filtering, was obtained at the left and the right occipital area (O1 and O2) in 11 normal subjects. Power in each hemisphere, phase difference and coherence between O1 and O2 were estimated at an alpha frequency. A laterality index of power was defined as (P(l)-P(r))/(P(l) + P(r)) where P(l) is a power value at O1, and P(r) at O2. In most of the subjects, laterality index decreased in the order: left half-field, full-field and right half-field stimulation. This relationship revealed greater SML responses on the ipsilateral occipital area. There were significant differences in laterality index among 3 visual field conditions, thus showing that full-field responses ranged in lateralization between the left and right half-field responses in most of the subjects. This hemispheric distribution suggests that half-field SML stimulation affected alpha activity selectively in each hemisphere, mostly in the ipsilateral hemisphere.

Adult↗
PubMed1992

Abnormality of background EEG determined by the entropy of power spectra in epileptic patients.

Relationships between epileptiform discharges and background activity were examined by power spectral entropy (PSE), measuring a degree of EEG irregularity. The EEGs were recorded from 10 electrodes placed at F3, F4, C3, C4, T3, T4, P3, P4, O1 and O2 in 11 epileptic patients with widespread lateralized spike and wave complexes (SWCs). Bipolar records were also made from the antero-posterior derivations. The locations of the maximum PSE coincided with those of the maximum amplitude of SWC in most of the patients. Bipolar derivations with the maximum PSE always included the locations with the maximum PSE obtained from a linked ears reference. Pearson's correlation coefficient between PSE and SWC amplitude was 0.62 +/- 0.14 (mean +/- S.D.) in 11 patients, thus indicating that the scalp distribution of PSE was closely related to that of the amplitude of SWC. These findings suggest that the background EEG is disorganized in or near the epileptogenic focus. A focal background abnormality can therefore be estimated by PSE.

Adolescent↗
PubMed1992

AIDS-like disproportion of minor T-cell subsets in Japanese patients with Wegener's granulomatosis.

Fifteen Japanese patients with Wegener's granulomatosis (WG) were evaluated according to their lymphocyte subset abnormalities. Two colour immunofluorescent flow cytometry was used to distinguish the lymphocyte subset alterations. WG group showed a decrease in the percentage of CD4+ cells and the increase of CD8+ cells. Within the NK cell family, the functionally unidentified CD8+57+ cells were markedly elevated. The disproportion of the lymphocyte subsets (CD4+ decreases CD8+57+ increases) were similar to those of Acquired Immunodeficiency Syndrome (AIDS) and AIDS relating complexes (ARC). To assess silent infection of Human immunodeficiency virus (HIV), the polymerase chain reaction (PCR) was done for all patients to selectively amplify specific HIV proviral DNA sequences in peripheral blood mononuclear cells, HIV-1 proviral DNA was not found in any patients but these changes of WG might suggest a possible adaptive response to unknown viral infection.

AIDS-Related Complex↗