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Biomedical subjects

H Miyata

Publications and source records attributed to H Miyata.

At least 433 records · Page 24Linked to original sources
PubMed1978

Relationship between extracellular enzymes and cell growth during the cell cycle of the fission yeast Schizosaccharomyces pombe: acid phosphatase.

By using the intact cells of the fission yeast Schizosaccharomyces pombe, the activity of acid phosphatase (EC 3.1.3.2) was compared through the cell cycle with the growth in cell length as a measure of cell growth. The cells of a growing asynchronous culture increased exponentially in number and in total enzyme activity, but remained constant in average length and in specific activity, In a synchronous culture prepared by selection or by induction, the specific activity was periodic in parallel with the increase in average cell length. When hydroxyurea was added to an asynchronous or a synchronous culture by selection, both specific and total activity followed the same continuous pattern as the growth in cell length after the stoppage of cell division. When oversized cells produced by a hydroxyurea pulse treatment to the culture previously syndronized by selection were transferred to a poor medium, they divided synchronously but could hardly grow in the total cell length. In this experimental situation, the total enzyme activity also scarcely increased through three division cycles. These results suggested that the increase in acid phosphatase in dependent on cell elongation.

Acid Phosphatase↗
PubMed1975

Vestibular end organ mapping in the squirrel monkey.

Vestibular end organ mapping (surface preparation) was performed in squirrel monkeys by using succinic dehydrogenase staining. Comparing sensory hair cell counts and surface area measurements of the squirrel monkey to those of man and the guinea pig, the values obtained from the squirrel monkey were between those of man and the guinea pig. When regional (central versus peripheral) cell density was compared, the density of the peripheral area was 1.62X more on the average than that of the central portion.

Animals↗
PubMed1975

Superior vestibular nerve sectioning. Experimental studies in squirrel monkeys.

Spontaneous, positional, and paroxysmal positional nystagmus were studied before and after sectioning the superior division of the vestibular nerve and the anterior vestibular artery in squirrel monkeys. Histopathologic study of the temporal bones confirmed the degeneration of the macula utriculi with release of statoconia, but failed to identify the released utricular statoconia within the vestibular endolymphatic space in any animal. Postoperatively the animals consistently demonstrated direction-fixed spontaneous nystagmus until the end of the experiment (five months). Positional tests and Dix-Hallpike maneuver occasionally changed the intensity of the spontaneous nystagmus, but never elicited paroxysmal positional nystagmus. Possible reasons for not demonstrating paroxysmal positional nystagmus in the squirrel monkey are as follows: a resorption of statoconia; slight morphological alteration of the sensory epithelia of the posterior cristae; interference of the posterior crista function due to partial collapse of the membranous ampulla; the existence of interspecies difference; or possibly a faulty hypothesis regarding the etiologic mechanism of benign paroxysmal positional vertigo.

Animals↗
PubMed1975

Parametric study of postrotatory nystagmus in normal squirrel monkeys.

In order to find the most consistent nystagmic parameter following rotation, 16 healthy young adult squirrel monkeys were rotated from 0 to 200 degrees/sec with 1 degrees/sec2 constant angular acceleration and then abruptly stopped. This centric horizontal rotation was performed in a dark room without the eyes being covered. Horizontal eye movement of the postrotatory nystagmic response was recorded: maximum slow and quick phase eye speeds, nystagmic duration, amplitude, number of beats, and maximum average frequencies were studied. The maximum frequency of the nystagmic beats was statistically confirmed at the least variable parameter among the seven parameters. The importance of baseline establishment in the animal nystagmus experiment was emphasized.

Acceleration↗