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Biomedical subjects

H Shibasaki

Publications and source records attributed to H Shibasaki.

At least 325 records · Page 18Linked to original sources
PubMed1988

Treatment of essential tremor with arotinolol.

We investigated the effect of arotinolol, a new peripherally acting beta-adrenergic blocker, in 15 patients with essential tremor. The patients received 30 mg per day of arotinolol for 8 weeks. Accelerometer readings showed a significant reduction in amplitude of postural tremor after treatment. Action tremor also improved to essentially the same degree as postural tremor. The present findings support the view that the therapeutic effect of beta-blockers in essential tremor is mediated by peripheral beta-adrenergic receptors.

Adrenergic beta-Antagonists↗
PubMed1988

Recording of movement-related potentials from scalp and cortex in man.

Movement-related cortical potentials (MRPs) were recorded from scalp electrodes in 8 normal volunteers and from chronically implanted subdural electrodes in 7 patients who were being evaluated for surgical treatment of epilepsy. From subdural electrodes, a clearly defined, extremely localized slow negative potential preceding the voluntary movement of the middle finger (Bereitschaftspotential, BP) was recorded in the contralateral and ipsilateral hand sensorimotor areas. The negative slope (NS') began approximately 250 to 400 ms before EMG onset and was recorded exclusively from the contralateral hand sensorimotor area. Both BP and NS' were maximum in the hand motor area. Although a negative slope was recorded also from the supplementary motor area, whether that particular slope corresponded to BP or NS', or both, could not be determined. Three kinds of progressively steeper negative potentials starting around the onset of the EMG were identified: (1) the 'hand motor potentials' which were seen in the contralateral hand motor area and started immediately before EMG onset and peaked 130 +/- 32 ms after EMG onset; (2) the 'hand somatosensory potentials' seen in the contralateral hand somatosensory area which started simultaneously or immediately after the EMG onset; and (3) the 'vicinity potentials' seen in the immediate surroundings of the contralateral hand area and which started after the EMG onset. The 'hand motor potentials' had the highest amplitude. From these findings, we concluded that bilateral hand sensorimotor areas and the supplementary motor area participate in the 'preparation' of movements, but that mainly the contralateral cortex generates the discharges necessary to produce the actual movement.

Adolescent↗
PubMed1987

Determination of stable isotopically substituted histidine in human plasma by gas chromatography-mass spectrometry.

A gas chromatographic-electron-impact mass spectrometric method for the determination of stable isotopically substituted histidine in human plasma has been developed. Histidine was derivatized to alpha N-trifluoroacetyl-imN-carbethoxyhistidine n-butyl ester (TCB derivative) by a three-step reaction: an initial esterification by 3 M n-butanolic hydrochloric acid, followed by trifluoroacetylation with trifluoroacetic anhydride and then ethoxycarbonylation with diethyl pyrocarbonate. Quantitation was carried out by selected-ion monitoring on the molecular ions (m/z 379, 383 and 385) of the respective TCB derivatives of histidine, [1-15N,5,beta,beta-2H3]histidine (histidine-[M + 4]) and [1,3-15N2,5,alpha,beta,beta-2H4]histidine (histidine-[M + 6]). The sensitivity, specificity, precision and accuracy of the method were demonstrated to be satisfactory for application to a pharmacokinetic study of histidine after administration of a trace amount of stable isotopically substituted histidine (histidine-[M + 4]) in humans.

Chemical Phenomena↗
PubMed1987

Photic cortical reflex myoclonus.

Three patients with flash-evoked myoclonus were studied electrophysiologically. Myoclonic jerks were elicited at a fixed latency after the application of photic stimuli and were always preceded at a fixed time interval by extremely enhanced cortical evoked potentials. The enhanced electroencephalographic (EEG) responses to flash were widely distributed over the scalp and were maximal at the central region; the occipital response preceded the frontocentral response by 3.4 to 5.1 msec. The interval from the frontocentral EEG response to the flash-evoked myoclonus was similar to that from the giant somatosensory evoked potential to the electrically evoked myoclonus. Investigation of recovery of evoked cortical responses and of myoclonic jerks showed a period of extremely enhanced excitability of both central and peripheral phenomena following stimulus. All of these findings suggest a cortical reflex mechanism. The role of the occipital cortex in the pathogenesis of photic cortical reflex myoclonus remains to be elucidated.

Adult↗
PubMed1987

Elimination of EKG artifacts from EEG records: a new method of non-cephalic referential EEG recording.

A new method for eliminating EKG artifacts from EEGs was reported. Based on the simultaneously recorded EEGs and EKG, the procedure consisted of 4 steps: synchronized partition of the raw EEG record into segments with respect to the QRS complex of the EKG, averaging of the segments time-locked to EKG, repetition of the average artifact synchronized to EKG and subtraction of the estimate of the artifacts from the raw data. This method enabled the elimination of EKG artifacts from EEGs recorded by using the chin or the hand electrode as a reference. Features of the proposed method include: all signals are processed in digital instead of analogue form, the average EKG wave form is computed throughout the subtraction part of the recording instead of being computed only before the subtraction starts, in case of an on-line algorithm, the average EKG wave form is always updated to the point immediately preceding the real time of EKG subtraction, and by using the recursive form of exponential weighted averaging equation, the average EKG wave form can adapt appropriately to a change of the artifact wave form. By the high speed implementation of the procedure, the processed data of multi-channel EEGs can be obtained on-line with a delay of only 200 msec.

Adult↗
PubMed1987

Scalp topography of photic evoked potentials. Application of wave form decomposition technique.

A new method of wave form decomposition by using an evoked potential model was applied to the study of scalp topography of photic evoked potentials in 3 normal subjects. The parameters of the evoked potential model were composed of gain, natural frequency, damping ratio and time lag, and were determined in the frequency domain to minimize the square sums of the modeling error. By using the optimal model parameters, the wave form was decomposed into basic components. At least 4 components occurring within the initial 200 msec period after the stimulus onset were identified in all subjects and were shown to have different scalp distributions, suggesting different generator sources.

Adult↗
PubMed1987

Human auditory and somatosensory event-related potentials: effects of response condition and age.

In order to develop an experimental paradigm for clinical application of cognitive event-related potentials we have recorded these potentials in a group of 27 healthy Japanese, aged 20-78 years, using all 4 stimulus/response combinations of auditory or somatosensory stimuli requiring a counting or button-press response. In an oddball paradigm we recorded N1 and P2 components to frequent auditory stimuli and P100, N150 and P200 components to frequent somatosensory stimuli. These components were also observed in the target responses for their respective modalities together with N2, P270, P3 and slow-wave components. P3 latency increased linearly with age for all 4 experimental conditions, although this increase was not statistically significant for the somatosensory stimulus/button-press response combination. The latency of P270 also increased significantly with age for the auditory stimulus/button-press response combination but did not do so in either of the counting response conditions. The principal difference between the latencies of ERPs to auditory compared with somatosensory stimuli was that P3 was significantly longer for somatosensory stimulation, although differences in task difficulty may have influenced this finding. With regard to amplitude, N2, P3 and slow-wave were all significantly more positive for somatosensory compared with auditory stimulation. The topography of P3 evoked by somatosensory stimuli was most predominant at central electrodes, whereas the auditory P3 was larger parietally. The button-press response was associated with potentials which were smaller in amplitude and shorter in latency than those associated with the count response. The button-press response had a marked effect on the amplitude of P3 recorded at the vertex and the central electrode contralateral to the moving finger.

Adult↗
PubMed1987

Generator mechanisms of giant somatosensory evoked potentials in cortical reflex myoclonus.

In order to clarify the generator mechanisms for giant cortical evoked potentials, scalp topographies of somatosensory evoked potentials (SEPs) following various types of stimulation, including electrical nerve trunk and finger stimulation and mechanical stimulation, were investigated in 5 patients with cortical reflex myoclonus. For SEPs evoked by median nerve stimulation, not only the P25 and N34 components in central and parietal regions but also N25 in the frontal region were markedly enlarged in each patient. Their scalp distributions were not significantly different from those of normal subjects. P25 and N25, but not N34, were considerably attenuated by interfering tactile stimulation applied to the hand. The components corresponding to P25, N25 and N34 following electrical stimulation of the digital nerves as well as mechanical stimulation of the finger were also remarkably large and showed scalp distributions similar to those for median nerve SEPs. It is therefore concluded that the giant cortical SEPs of cortical reflex myoclonus are generated in those areas of the primary sensory cortex which generate normal SEPs, in response to an input, at least in part, from cutaneous afferents on the basis of an extremely enhanced cortical excitability.

Biomechanical Phenomena↗
PubMed1987

Somatosensory evoked potentials following stimulation of the lower limb in cortical reflex myoclonus.

Generating mechanisms of giant somatosensory evoked potentials (SEPs) following stimulation of the posterior tibial nerve as well as the big toe were investigated in three patients with cortical reflex myoclonus. Scalp distributions of recognisable components were very similar to those in normal subjects, except that their amplitude was much larger. The tibial nerve SEPs were remarkably attenuated by interfering tactile stimulation. Therefore, the giant SEPs observed in the present cases seem to be, at least partially, due to input from cutaneous nerve fibres on the background of extremely enhanced excitability in area 3b of the primary sensory cortex where normal SEPs are generated.

Adolescent↗
PubMed1987

Voice tremor: dysregulation of voluntary expiratory muscles.

We studied three patients: two with voice and hand tremor, and one with voice tremor. Voice tremor was associated with synchronous rhythmic contraction of cricothyroid and rectus abdominis muscles, but not always vocalis muscle. Voice tremor was manifested only in voluntary phonation or expiration, not in involuntary phonation, voluntary inspiration, or involuntary expiration and inspiration (breathing at rest). Impaired regulation of the CNS programs innervating the voluntary expiratory muscles probably causes voice tremor. Clonazepam and propranolol were helpful in blinded studies.

Clonazepam↗
PubMed1987

Incidence of antibody to HTLV-I is not increased in Japanese MS patients.

To examine the association between MS and anti-human T-cell lymphotropic virus-I (HTLV-I) antibody, we studied serum and CSF antibody to HTLV-I in 27 Japanese MS patients by an indirect immunofluorescence method sensitive and specific enough to detect carriers of HTLV-I. The antibody was detected in 3 of 27 MS patients (11.1%), in 4 of 48 patients (8.3%) with other neurologic diseases, and in 8.3% of 2,500 healthy blood donors. There was no significant difference in the incidence between the three groups. The titer of the antibody was low in CSF when compared with that in serum in all seropositive MS patients. Fluctuations in the CSF antibody titer were not observed in any of 14 MS patients sampled repeatedly.

Adult↗
PubMed1987

CSF mononuclear cell subsets in active MS: lack of disease-specific alteration.

We studied CSF mononuclear cell subsets in MS and acute aseptic meningoencephalitis, using seven monoclonal antibodies. Ia-bearing cells were more frequent in active MS than in stable MS. In active MS, the percentage of Ia-bearing cells was higher than M5 cells or B7 cells, suggesting that Ia-positive T cells appear when the disease is active. However, there was no difference in the proportion of CSF cell subsets in active MS and acute aseptic meningoencephalitis; the changes in MS are similar to acute inflammatory reactions.

Adolescent↗
PubMed1987

A case of myasthenia gravis associated with thymoma, multiple schwannomas and monoclonal IgA gammopathy.

Myasthenia gravis, malignant thymoma, multiple schwannomas and monoclonal IgA gammopathy coexisted in a 54-year-old Japanese man. Serum acetylcholine receptor antibody activity was located in the IgG fraction, but not in the paraprotein peak. It was speculated that all these disorders might fall under the spectrum of the diseases associated with thymic abnormality or that some growth factors might induce neoplasms and activation of B cell clones of autoantibodies (including acetylcholine receptor antibody) in this case.

Autoantibodies↗