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Biomedical subjects

K Nakata

Publications and source records attributed to K Nakata.

At least 577 records · Page 32Linked to original sources
PubMed1979

The application of the Gierer-Meinhardt equations to the development of the retinotectal projection.

Model calculations are presented for the several properties of the development of the retinotectal projection in amphibians and fishes, using the Gierer-Meinhardt equations. One of these properties is the maintenance of topographic mapping between the retina and the tectum during their development despite the fact that the two tissues grow in morphologically different ways. Another is the existence of a "critical period", at which the coordinates of the retina with respect to the tectum are irrevocably determined. It is assumed that the connections between the retinal and the tectal cells are made on the correspondence of positional markers which are given as a form of the distribution of a specific activator, the dynamics of which is described by the Gierer-Meinhardt equations. The monotonic distributions of the activator and the existence of the critical period are shown by a computer simulation of the proliferating retina. Several changes of the retinotectal projection after surgical operations on the retina or the tectum are also explained.

Amphibians↗
PubMed1979

Effect of low protein diet and surplus of essential amino acids on the serum concentration and the urinary excretion of methylguanidine and guanidinosuccinic acid in chronic renal failure.

20 patients with moderate renal failure (serum creatinine 4.5--12.0 mg/dl) and some uremic symptoms on a diet ad libitum were treated with a high caloric diet containing 0.5--0.7 g/kg/day protein, supplemented with eight essential amino acids and histidine in the form of solution and/or granules. During the treatment uremic symptoms subsided or diminished without the signs of malnutrition, SUN and the ratio SUN/S-creatinine fell and the nitrogen balance and the ratio N-balance/intake N improved. The serum concentration and the urinary excretion of MG and GSA of the 12 patients were determined by Stein's method using the modified Sakaguchi reaction. In all patients, the serum concentration and the urinary excretion of MG and GSA diminished remarkably during the treatment with a low protein diet alone and furthermore with a low protein diet and essential amino acid supply. We concluded that conservative treatment -- low nitrogen diet supplemented with sufficient calories and essential amino acids -- improved the nutritional state of uremic subjects, and decreased the metabolic production of MG and GSA. The results show that the supplementation of essential amino acids to uremic patients may be a useful treatment.

Adult↗
PubMed1979

Quantitative analysis of dermatoglyphics. (2) Dermatoglyphic patterns.

Using medical students as controls, we devised a method of quantitative analysis of dermatoglyphic patterns. We calculated the frequency of appearance of each of the patterns and obtained the probability of occurrence of the dermatoglyphics of each of the controls. We showed usefulness of this method by presenting some examples of congenital anomalies where this has been put to use. Furthermore, patients with congential heart disease were compared with controls by this method.

Dermatoglyphics↗
PubMed1979

[Vaginal smear cycle in 4-day cyclic Chinese hamsters, Cricetulus griseus].

The contents of vaginal smear of 4-day cyclic Chinese hamster (Cricetulus griseus) was investigated every 3 hours for 5 days. A light-dark cycle of 14--10 hr was used with the lights turned on at 6 : 00 a.m. Estrous cycle of the Chinese hamster determined by vaginal smears can be divided into 6 periods. The proestrous phase started at about 0 : 00 of day 1, the day of the proestrous phase was designated as day 1 of the estrous cycle. In the afternoon of the same day 1, nucleated epithelial cells gradually increased in number (proestrus : I), and the vaginal contents became to consist solely of nucleated epithelial cells at about 18 : 00 to 21 : 00 (estrus : II). At about 0 : 00 of day 2, however, nucleated epithelial cells were superseded suddenly by cornified epithelial cells, and this phase lasted for 9 to 12 hr (metestrus I : III). Towards the end of the cornified stage, nucleated cells appeared in short duration (metestrus II : IV). And then, in the evening of day 2, leucocytes gradually increased in number with degeneration of nucleated cells (diestrus I : V-1). On day 3, vaginal smear contained a large amount of mucus as well as degenerated nucleated cells and leucocytes (diestrus II : V-2). At about 21 : 000 of day 4, some cornified epithelial cells were seen and then proestrous stage was returned. The females were mated with 3 to 5 males in the evening of day 1, copulation was confirmed in 83.7% females in the next morning,thus the copulation in the Chinese hamster may be thought to occur during the vaginal smear stage of nucleated epithelial cells (estrous phase), i.e. about 18 : 00 to 24 : 00 of day 1.

Animals↗
PubMed1979

[Intracranial hemorrhage in autopsy cases with occlusion of the circle of Willis (author's transl)].

Seventeen autopsy cases with occlusion of the circle of Willis were examined clinicopathologically. These patients ranged in age from 8 years to 64 years and consisted of 6 males and 11 females. The following results were obtained. 1. Fresh and massive intracerebral hemorrhage was confirmed in 13 of 17 patients and cerebral infarct in 4 of 17 patients. 2. Among these 13 patients, massive hemorrhage was found in basal ganglia, thalamus and hypothalamus of 9 patients, and in thalamus, cerebral peduncle and midbrain of 4 patients. 3. Rupture of the dilated muscular-type arteries was noted in the thalamus and basal ganglia in 2 of 13 patients. Ruptured arteries with organization of the lumen were found in the old hemorrhagic foci in one of them. 4. Overgrown and dilated arteries, branching off from the circle of Willis, were confirmed in 11 patients. These arteries consisted of "perforating" arteries well developed as collateral circulation. 5. No ruture in these arteries of the subarachnoidal spaces was found in 11 patients. In one of them, a small saccular aneurysm was found. These findings strongly suggest that in patients with occlusion of the circle of Willis intracerebral rupture of overgrown "perforating" arteries as collateral circulation may be the main cause of intracranial hemorrhage and intracerebral hemorrhage due to rupture of the arteries may be repeated.

Adolescent↗
PubMed1978

Effect of arginine or creatinine administration on the urinary excretion of methylguanidine.

The metabolic pathway of methylguanidine (MG) is mainly speculated from the change in urinary excretion of MG in the arginine (Arg)-injected normal rat, the creatinine (Cr)-injected normal rat, and the Arg-injected uremic rat. 15N-Arg was ingested to 2 uremic patients. Arg administration resulted in marked increase in urinary MG excretion both in the uremic rat and patient, but not in the normal rat. In the first phase of the 15N-Arg ingestion experiment, a rapid rise of 15N atom percent excess of urinary MG was observed in the uremic patient. In the second phase of this study, after 24 h of 15N-Arg ingestion, the 15N atom percent excess of urinary Cr and that of MG closely paralleled. These findings imply that there might be two metabolic origins of MG: one is a formation of MG from Arg itself or an Arg metabolite other than Cr, the other a pathway producing MG via Cr. The former is compatible with the hypothesis by Cohen.

Animals↗