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Biomedical subjects

K Amano

Publications and source records attributed to K Amano.

At least 307 records · Page 17Linked to original sources
PubMed1986

[Musical murmurs: phonocardiographic, echocardiographic and Doppler echocardiographic study].

Musical murmurs are probably related to the vibrations of some structures in the cardiovascular system, and this may be reflected in the characteristic stripes which are recorded by the fast Fourier transformation (FFT) of the pulsed Doppler echocardiography (so-called FFT stripe). In the present study, we demonstrated new stripes by color Doppler echocardiography, which were composed of multiple warm and cold color bands which we termed color Doppler stripes (CD stripe). An experiment was performed to obtain Doppler signals from the surface of a vibrating tonometer at a frequency of 128 Hz. When the CD stripe was obtained, a similar FFT stripe was also recorded from the same sampling site. Fourteen patients with musical murmurs were selected from 2,000 consecutive phonocardiographic records made during the last one and a half years. The CD stripe was obtained in three and the FFT stripe in six. When both stripes were obtained, the FFT stripe was always obtained if we set carefully the sample site in the CD stripe, and these two were consistent in timing. We concluded that, in view of the close correlation between the CD stripe and the FFT stripe, the newly observed CD stripe is also a characteristic finding reflecting a regularly vibrating structure. The technical feasibility of color Doppler echocardiography to detect fine movements of structures may be helpful in the study of musical murmurs.

Adult↗
PubMed1986

[Association of anorexia nervosa and mitral valve prolapse].

Four cases of anorexia nervosa recently encountered were reported in respect to their cardiovascular manifestations including prolapse of the cardiac valves and other poorly recognized cardiac findings. All four patients, aged 13 to 32 years, were women and had marked emaciation (35 to 44% weight loss of the ideal body weight) with typical hormone abnormalities. Chest radiographs showed a small cardiac shadow, and sinus bradycardia with low voltage was present in their electrocardiograms. One case, 13-year-old, had a mid-systolic click and occasionally a late systolic murmur, and also an abdominal continuous hum. Echocardiography including two-dimensional color flow-mapping disclosed mitral valve prolapse in all, and tricuspid valve prolapse in two. Mild to moderate pericardial effusion was noted in all between the right ventricle and diaphragm, and pericardiocentesis in one case had no effect on the valve movements. No inflammatory changes were observed in the specimen of the pericardium and also of the fluid. An association of mitral valve prolapse and anerexia nervosa was discussed based on the previous studies, but the final conclusion remains unknown.

Adolescent↗
PubMed1986

[Ascending limb of the N20 component of somatosensory evoked potential--an analysis on direct recording from the human midbrain].

Somatosensory evoked potential elicited by median nerve stimulation at the wrist was recorded from five loci on the trajectory of stereotactic rostral mensencephalic reticulotomy. Four distinct positive waves followed by one negative wave, the peak latency being 16.3 msec, were recorded from the rostral midbrain reticular formation near the medial lemniscus. The four positive waves were named as I, II, III, and IV respectively. Peak latency of these positive waves was 12.6, 13.7, 14.7 and 15.8 msec respectively. The first two positive waves (I, II) corresponded to P13 and P15 recorded over the scalp. The other two positive waves (III, IV) changed their polarity to negative at the level of the ventral thalamus and formed the ascending limb of N20 recorded over the scalp. N16 was most prominent at the level of nucleus ventrocaudalis externus. These findings suggest that the ascending limb of N20 is composed of at least three components, wave III, IV, and N16. The present report is compatible with the investigations by Abbruzzese et al.2) and Eisen et al.11) that there are several distinct dipoles between P15 and N20 of somatosensory evoked potential in man.

Afferent Pathways↗
PubMed1986

[Significance probability mapping of brain electrical activity--its problem and specified z-statistic mapping].

Significance probability mapping (SPM) of brain electrical activity first described by Duffy et al. is useful tool for studying functional aspects of brain disease. Z-statistic SPM is able to identify the area of brain electrical activity deviated with statistic significance from the control group. The problem of this method is, however, that the nature of deviation, i.e., whether it is increase or decrease of electrical activity, can not be displayed. From this point of view, we attempted to use modified z-statistic method. Statistically deviated region and its nature can be clearly displayed on the same picture by analyzing EEG with this method. This method can be applied to SPM of evoked potentials. SPM is not yet complete method for the assessment of brain electrical activity, but there is much room for adopting other statistic method that is more suitable for the aim of the study. Functional aspects of the brain will be more readily clarified by the use of modified SPM and by combination with findings of CT scan, NMR and PET that can give morphological and metabolic information.

Adult↗
PubMed1986

[Influence of hemisphere lesions on the contralateral blink reflex].

Electrically elicited blink reflexes were investigated in 28 patients with unilateral hemispheral lesion. The reflex evoked by electrical stimulation of the supraorbital nerve contralateral to the side of the hemispheral lesion was absent or depressed in 14 out of 28 cases. The abnormal patterns of the blink reflexes were devided into four different types (Type AB, Type AD, Type EB, and Type AB-EB). The Type AB, recorded in 4 cases, consisted of bilateral absence of late component (R2) when the supraorbital nerve on the non-lesion side was stimulated. In contrast, the reflex responses were almost normal bilatarally when the stimulus was applied to the nerve on the lesion side. The Type AD was observed in 2 cases. When the stimulus applied on the non-lesion side, both ipsilateral and consensual R2 were markedly delayed in latency. The Type EB was seen in one case. In this type the absence of the late component (R2) was confined to the clinically affected side independent of the side of stimulation. The Type AB-EB was observed in 4 cases. This type consisted of bilateral absence of R2 component after stimulation on the non-lesion side as seen in Type AB. However, when the stimulus applied on the lesion side, R2 component was only elicited on the ipsilateral side of stimulation. Based on our results, the authors emphasize that abnormality of the contralateral blink reflex in the patients with unilateral hemispheral lesion showed not only Type AB or Type AD but also Type AB-EB which may indicate lowered excitability of bulbar lateral reticular formation of the lower brain stem as well as spinal trigeminal system. This type was presumably due to loss of facilitatory influences associated with the contralateral hemispheral lesion, closely correlated with the lower postcentral region advocated by Ongerboer de Visser.

Adult↗
PubMed1986

Boron distribution analysis by alpha-autoradiography.

The distribution of the boron-10 compound, Na2 10B12H11SH, which is now in clinical use for boron neutron capture therapy for brain tumors, was studied topographically and quantitatively in rats using neutron-induced alpha-autoradiography. Transplanted intracerebral tumors in Sprague-Dawley rats were used. In the normal brain, only a minute amount of 10B (less than 1 microgram 10B/cm3) was found in the brain parenchyma, except for the infundibulum and area postrema. Boron-10 accumulated in the brain tumors. The tumor-to-blood concentration ratio of 10B increased with time after injection and reached unity 12 hr after injection. The tumor concentration calculated at that time was 18 micrograms 10B/cm3. This study clearly shows that this 10B compound accumulates in the transplanted rat tumors in the brain and that tumor concentration and tumor-to-blood ratio of 10B can provide a sufficient condition for brain tumor treatment.

Animals↗
PubMed1986

[Chronological changes in the blink reflex and MRI in a patient with lateral medullary infarction].

Recently, the brainstem pathways of bilateral late reflexes (R2) of electrically elicited blink reflex have been well established. An afferent delay or block of the late reflexes is closely related to a lesion of the lateral medullary portion. The chronological alteration of blink reflex (BR) was studied to compare with radiological abnormalities on MRI in a patient with lateral medullary infarction on the right side. A diagnosis of Wallenberg syndrome was made clinically and location of the lesion was identified in detail by MRI. The infarcted region which was well demonstrated as an increased intensity area on SE images obtained 52 days after the onset of symptoms was much smaller than that on SE as well as on IR image 21 days after the onset of symptoms. Therefore, it was concluded that more than half of the increased intensity area on the SE images obtained 21 days after the onset of symptoms recovered from the condition of being extremely damaged by ischemia on the right lateral medullary portion in this patient. On the other hand, in the initial BR 26 days after the onset of symptoms, the late reflexes (R2) were consistently absent bilaterally when the affected side (right) was stimulated and normal when the normal side (left) was stimulated. This type of BR abnormality is compatible with an afferent block of late reflexes (R2). The early reflex (R1) was normal on either side. Whereas in the second BR at 55 days after the onset of symptoms, the late reflexes turned to be normal in latency when the right side was stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Blinking↗
PubMed1986

Assessment of outcome prediction in severe brain damage patients with brainstem auditory evoked response.

Patients with various neurological disease resulting in severe brain damage and having Glasgow Coma Scale (G.C.S.) score of less than ten (mean 5.6) were studied with brainstem auditory evoked response (BAER) during the first few days of onset. Among them were subarachnoid hemorrhage, head injury, intracerebral hemorrhage, pontine hemorrhage, intraventricular hemorrhage and bleeding tumor. BAERs were graded into four levels from one (normal) to four (most abnormal). Outcomes were categorized through the Glasgow Outcome Scale. Comparison of the results between BAER and G.C.S. as predictors of outcome was quite similar. Both were reliable in terms of predicting a correctly pessimistic outcome (90% or more), but not a correctly optimistic outcome (40% or less).

Adolescent↗
PubMed1985

[Evidence for the internalization and degradation of insulin in cultured Bri-7K human lymphocytes].

We have studied the internalization of insulin and the mechanism of insulin degradation in cultured Bri-7K human lymphocytes. The internalization of 125I-insulin was observed by using an acid extraction technique by Heigler's method which removed surface-bound insulin, leaving only intracellular insulin associated with cells. Insulin binding to Bri-7K cells reached a peak at 15 min and showed a gradual fall thereafter at 37 degrees C. Internalization of insulin rose with a peak in 30 min, and its rate was nearly 25% of the total specific cell-associated radioactivity. Insulin degrading activities in Bri-7K cells were examined as to precipitability with trichloroacetic acid (TCA method), Sephadex G-50 column chromatography (gel chromatography method) and the ability to bind to specific receptors on Bri-7K cells (rebinding method). Under conditions demonstrating that the insulin degradation didn't take place in the medium but was cell-mediated, the insulin degradation was not demonstrated by the TCA method. Chromatographic studies showed that the extractable radioactivity consisted almost entirely of intact insulin, whereas the supernatant and the nonextractable radioactivities consisted of large molecular weight material and intact insulin. Thus, the apparent degradation of insulin was not detectable by the TCA and gel chromatography methods, however, using the rebinding method, we could obtain results demonstrating that fair amounts of insulin in the supernatant were degraded. These results suggest that the products of insulin degradation are peptides with a molecular size similar to insulin itself but with little or no receptor binding activity. In conclusion, insulin internalizes into Bri-7K cells at physiological temperature, and the mechanism of insulin degradation in Bri-7K cells seems to be a limiting proteolysis of insulin by specific enzyme(s).

Cell Membrane↗
PubMed1985

Electron microscopic studies of lipopolysaccharides from phase I and phase II Coxiella burnetii.

Lipopolysaccharides from phase I (LPSI) Coxiella burnetii Ohio and Nine Mile strains and from phase II (LPSII) Nine Mile stain were negatively and positively and examined with the electron microscope. The ultrastructure of LPSI and LPSII positively stained with uranyl formate or uranyl acetate was ribbon-like. When negatively stained with uranyl acetate, LPSI was ribbon-like but LPSII exhibited hexagonal lattice structures. However, LPSII stained negatively with sodium phosphotungstate and ammonium molybdate exhibited hexagonal lattice ultrastructures which were not identical to those observed when negatively stained with uranyl acetate. The hexagonal lattice structures formed in vitro were due to the interactions of LPSII and the staining reagents rather than to protein-LPS interactions. The differences in the ultrastructures of LPSI and LPSII are undoubtedly based on variations in their chemical composition.

Coxiella↗
PubMed1985

A new apparatus for CT-guided stereotactic surgery.

Combining whole-body CT scan with a stereotactic system, the authors have developed and applied clinically an apparatus which readily provides intraoperative CT images, making it possible to confirm the location of the target point and ascertain the intraoperative environment. It takes about 9 s to obtain a CT image. Our purpose is to make stereotactic surgery, a kind of blind surgery, as safe and reliable as a visualized procedure by intraoperative CT scanning. By the method, in which there is very little invasion under local anesthesia, evacuation of deep-seated intracerebral hematomas as well as brain abscesses and also biopsy or brachytherapy of brain tumors in the brain can be done with safety and reliability.

Cerebral Hemorrhage↗
PubMed1985

Cerebral-evoked responses elicited by direct stimulation of the lateral spinothalamic tract in the human.

The authors recorded cerebral-evoked responses elicited by direct stimulation of the human lateral spinothalamic tract (LST) during percutaneous cordotomy to investigate central conduction of noxious stimuli. These responses consisted of four negative potentials, peak latency being 3.8 (N1), 8.4 (N2), 12.2 (N3) and 21.9 (N4) ms respectively. N1 showed wide distribution over the scalp and was considered to be of subcortical origin. N2-N4 were distributed in both the temporal and central area. The different distribution pattern of N2-N4 from conventional somatosensory-evoked potential suggested a different projection of LST from the medial lemniscus system.

Adult↗
PubMed1985

CT-guided stereotactic surgery for evacuation of hypertensive intracerebral hematoma.

During the last 3 years, 46 cases of hypertensive intracerebral hemorrhage were treated by CT-guided stereotactic surgery. Our present report is concerned with the evaluation of this procedure in the treatment of hypertensive intracerebral hematoma, in terms of the rate of aspirated hematoma and follow-up study of patients. It is difficult to draw any definite conclusion about the operative indications. CT-guided stereotactic aspiration, however, can be evaluated as a less invasive and more definitive treatment of intracerebral hematoma in the basal ganglia and thalamus.

Aged↗
PubMed1985

[Mechanism of systolic anterior motion and left ventricular outflow obstruction in hypertrophic obstructive cardiomyopathy].

Two-dimensional echocardiographic studies were performed for 22 patients with asymmetric septal hypertrophy and systolic anterior motion (SAM) of the mitral valve to clarify the mechanism of SAM and left ventricular outflow obstruction. The long-axis view of the left ventricle showed that a distal portion of the anterior mitral leaflet became surplus when the mitral valve was closed in 15 of 16 patients with SAM-septal contact and in four of six patients without it. In these patients, the mitral leaflet coaptation was displaced anteriorly, and/or the anterior leaflet was elongated, showing an anterior motion. In an unusual patient with SAM-septal contact, a distal portion of the long posterior mitral leaflet was surplus. The remaining two patients without SAM-septal contact had a rather widely coapted portion of the mitral leaflets. The distal surplus portion and the coapted portion of the mitral valve were displaced anteriorly prior to the onset of ejection, and moved forward and protruded into the outflow tract more rapidly and more excessively than the papillary muscles during early to mid systole in all patients. Then, the distal mitral valve and the chordae tendineae adopted the configuration of an inverted V in mid systole. The tip of the surplus leaflet contacted the interventricular septum in patients with SAM-septal contacts. In the short-axis view of the left ventricle, the central portion of the distal mitral valve moved forward excessively and bent like an inverted U during early to mid systole. Therefore, SAM of the distal mitral valve is thought to be caused by the hydrodynamic force generated by the ejection flow. This force is supposed to be not only due to the Venturi effect, but is more properly understood as a "pushing force". Left ventricular outflow obstruction is considered to be formed by the protruding distal mitral valve and the hypertrophied septum.

Adolescent↗