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Biomedical subjects

K Amano

Publications and source records attributed to K Amano.

At least 415 records · Page 23Linked to original sources
PubMed1978

[Bulbar reticular control on DSCT activity in decerebrate cats (author's transl)].

Effects of bulbar reticular tetanic stimulation on the responses of dorsal spinocerebellar tract (DSCT) units were studied in the decerebrate cat. The conditioning stimulation of lateral or paramedian reticular nucleus was found to reduce polysynaptic activation of DSCT cells (type 3 response) selectively without affecting either the spontaneous background discharge or the monosynaptic activation (type 1 response) or inhibition (type 2 response) by afferent inputs from the peripheral nerves of hindleg. These results show that the descending inhibition to the polysynaptic activation of DSCT cells occurs presynaptically by reticulospinal pathways from brain-stem reticular formation.

Animals↗
PubMed1977

The action of lysozyme on peptidoglycan with N-unsubstituted glucosamine residues. Isolation of glycan fragments and their susceptibility to lysozyme.

1. A peptidoglycan preparation N-acetylated at about 30% of glucosamine residues was obtained by the treatment of the lysozyme-resistant cell wall paptidoglycan of Bacillus cereus with acetic anhydride at pH 7. Fractionation of dialyzable material resulting from lysozyme digestion of the glycan component of this peptidoglycan preparation yielded five oligosaccharides designated as S1 to S5 besides the disaccharide GlcNAc-MurAc. 2. Oligosaccharide S3, which accounted for about 30% of the disaccharide units recovered as disaccharides and oligosaccharides, was identified as GlcN-MurAc-GlcNAc-MurAc. Oligosaccharide S1, accounting for about 20% of the disaccharide units recovered, was characterized as GlcN-MurAc-GlcN-MurAc-GlcNAc-MurAc, while oligosaccharide S2, present in a smaller amount, as GlcNAc-MurAc-GlcN-MurAc-glcNAc-MurAc. Oligosaccharides S4, and S5, present in small amounts, were identified as GlcNAc-MurAc-GlcNAc-MurAc and MurAc-GlcNAc-MurAc, respectively. 3. Oligosaccharides S1, S3 and S5 proved to be completely insusceptible to lysozyme, whereas S2 was digsted by lysozyme to produce GlcNAc-MurAc and S3. S1 was found to act as a more potent inhibitor than S3 in lysozyme-catalyzed digestion of polysaccharides. 4. The results obtained show that the lysozyme-catalyzed hydrolysis of peptidoglycan oligosaccharides had an obligatory requirement for the N-acetyl group on the glucosamine residue located in subsite C in the enzyme-substrate complex.

Bacillus cereus↗
PubMed1977

Echocardiogram of the pulmonary valve. Variability of the pattern and the related technical problems.

In order to examine the variability of the pattern due to the location and direction of the ultrasonic transducer, echocardiograms of the pulmonary valve were obtained from different precordial areas in 28 patients with various diseases and in 3 normal subjects. By higher positioning of the transducer, the diastolic slope became slower or upward and the 'a' wave became indiscernible, giving the pattern of pulmonary hypertension even in the normotensives. The anterior cusp was also detected by tilting of the transducer in some cases. Systolic time intervals (STI) of the right ventricle, however, were not influenced by the beam angle. The present data strongly suggests that the echocardiogram of the pulmonary valve should be carefully evaluated in the light of the spatial relationship of the echo beam and the valve in order to give the diagnostic importance.

Adult↗
PubMed1977

Human chorionic gonadotropin produced by ectopic pinealoma in a girl with precocious puberty. Case report.

A case is reported in which a human chorionic gonadotropin (HCG-)-producing ectopic pinealoma was found in a 5-year-old girl with precocious puberty. Physical examination revealed abnormal breast enlargement. Endocrinological study disclosed a high plasma HCG concentration of 1192 ng/ml with a normal follicular stimulating hormone (FSH) level. The HCG content of the tumor was as high as 400 ng/mg of acetone dried tissue, but no FSH was detectable. This is the first reported case of precocious puberty associated with pineal tumor in a female.

Cerebral Ventricle Neoplasms↗
PubMed1977

[A case of HCG-producing ectopic pinealoma in a girl with precocious puberty (author's transl)].

HCG-producing ectopic pinealoma of two cell pattern type was demonstrated in a 5-year old girl who presented precocious puberty and bilateral choked discs. The tumor was localized at the anterior third ventricle and suprasellar region. Endocrinological findings are as following: Plasma basal LH was markedly elevated to 306 mIU/ml and HCG was elevated to 1,192 ng/ml. Provocative test of hypophyseal function revealed low response. Plasma estrogen was not detectable. HCG content of resected tumor tissue was elevated to 400 ng/mg. FSH, however, was not detectable. Histological findings of this tumor showed atypical teratoma, so-called two cell pattern pinealoma. Electron microscopic findings revealed two types of cells, dark and clear cells. Many secreting granules were found in the dark cells. In this case, HCG in plasma, CSF and tumor tissue was remarkably elevated. In addition, plasma FSH was also elevated to 8.9 mIU/ml. Precocious puberty associated with tumor in the pineal-suprasellar region has been seen only in boys. There has been no case report of precocious puberty in girls. This case is the first female case is which HCG-producing ectopic penealoma is caused in precocious puberty.

Brain Neoplasms↗
PubMed1977

[Computerized tomography (CT), EMI scanner, in the diagnosis of acute traumatic intracranial hematomas (author's transl)].

Eighteen examinations of acute head trauma have been performed using computerized tomography (CT), EMI scanner, before and after operation in our department since September, 1975. Diagnostic findings in CT before emergency operations of 5 cases including epidural hematoma (1), subdural hematoma (2), intracerebral hematoma (1), and combined hematoma (1) were presented and the diagnostic value of this new method was compared with that of cerebral angiography. CT was proved to be highly valuable in the diagnosis of not only intracranial hematomas but also cerebral edema, cerebral contusion and other abnormalities of the brain structures in head injury.

Adolescent↗
PubMed1977

[A study of excitability changes in DSCT neurons of the cat (author's transl)].

Excitability changes in the dorsal spinocerebellar tract (DSCT) neurons of the cat were extracellularly studied with correlation analysis. Most of the interval histograms were classifed as normal distribution, and occasionally bimodal distributions were observed, which resulted from an occasional "double spiking" in the spontaneous background discharge (BD). The conduction velocity was measured in 72 DSCT fibers. The histogram showed a peak at 40-50 M/S. The majority of the units had BD with coefficient of variation less than 0.2, which suggest BD with regular firing. Based on cross-correlelograms, DSCT responses to electrical stimulation of the muscle nerves of the hind leg were classified into at least three types. Type 1 response, constituted approximately one-fifth of the total, is monosynaptic activation. Type 2 response, observed most frequently (47%), is inhibition of DSCT cells with a short latency. Type 3 responses, observed nearly as often as type 2 (34%), is a long latency excitation, undoubtedly polysynaptic. Changes in stimulation intensity showed complex changes in the pattern of response. Type 1 and 2 responses were unaffected by increasing stimulus rate. Peak correlations in type 3 response were reduced by increase in stimulus rate. There were no data demonstrating feedback circuitry associated with collaterals of DSCT axons. This suggest that axon collaterals have no direct effect on the activity of Dsct cells.

Afferent Pathways↗
PubMed1977

Echocardiogram in pulsus paradoxus. Respiration dependent cyclic changes in mitral and aortic valve motion: a case report.

The mechanism of production of pulsus paradoxus was echocardiographically studied in a 74-year-old male with subacute effusive-constrictive pericarditis which developed to constrictive pericarditis under the observation. Echocardiography disclosed the following phenomena during inspiration: 1) mitral valve did not open until the atrial systole, probably because of the lack of antegrade mitral flow during rapid filling phase (the E wave was not observed), 2) concomitantly, aortic valve opening decreased markedly in its grade, and 3) left ventricular ejection time (LVET) decreased and pre-ejection period (PEP) increased, resulting in a higher PEP/LVET ratio (up to 1.32). The opposite was true during expiration (PEP/LVET ratio was 0.40). This is probably the first case, in which the mechanism of pulsus paradoxus was investigated by aortic and mitral valve echograms.

Aged↗