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Biomedical subjects

K Sasaki

Publications and source records attributed to K Sasaki.

At least 19 recordsLinked to original sources
PubMed1979

Partial purificationand characterizationof a factor which stimulates an increase in ornithine decarboxylase activity in the liver from tumor cell-free ascites fluid.

A factor responsible for stimulating an increase in ornithine decarboxylase activity in the liver of mice was found in tumor cell-free ascites fluid of mice 3 days after inoculation of tumor cells. The factor was purified about 70-fold in 25% yield from tumor cell-free ascites fluid. As little as 1 microgram of protein of purified fraction, injected intraperitoneally into normal mice, significantly increased the activity of ornithine decarboxylase in the liver. The most active preparation of the factor formed two major protein bands on analytical polyacrylamide gel electrophoresis and both these bands stained with periodic acid-Schiff's reagent. The factor was a heat-labile, alkaline-stable, acidic protein with a molecular weight of more than 300 000. It was inactivated by treatment with 10 mM dithiothreitol, 5 M urea, pronase or mixed glycosidase, but was stable on treatment with DNAase, RNAase or neuraminidase.

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PubMed1979

Projection of the cerebellar dentate nucleus onto the frontal association cortex in monkeys.

Stimulation of the cerebellar dentate nucleus in monkeys elicited responses in the frontal association cortex (area 9) on the contralateral side to the stimulation, in addition to those in the motor (area 4) and premotor (area 6) cortices which were reported previously. The responses in the frontal association cortex were characterized by surface positive-deep negative field potentials in the cortex. They contrasted with surface negative-deep positive potentials in the motor and premotor cortices on the same dentate nucleus stimulation. In the rostral part of the premotor cortex (area 6) on the border of area 9, both types of responses were induced and admixed. The relay nucleus of the thalamus was suggested for the dentate-induced responses in the frontal association cortex.

Animals↗
PubMed1979

Influences of cerebellar hemispherectomy on slow potentials in the motor cortex preceding self-paced hand movements in the monkey.

With chronically implanted electrodes, surface negative and deep positive, slowly increasing potentials were recorded in the forelimb area of the motor cortex prior to self-paced movements of the contralateral hand in monkeys. The slow premovement potentials were markedly reduced in size after ablation of the cerebellar hemisphere on the contralateral side to the motor cortex under recording. It was suggested that the cerebellar hemisphere (neocerebellum) participates in preparing the activity of the motor cortex prior to voluntary movements.

Animals↗
PubMed1979

Retrograde transport of horseradish peroxidase in sciatic nerve of rats and dystrophy mice.

The relationship between nerve or muscle activity and retrograde HRP transport was studied in rat Sciatic nerve and in dystrophy mice. sciatic nerve stimulation facilitated transport to 250% of control level, while colchicine decrease transport depending on dosage. Tendonectomy as well as colchicine treatment ultimately decreased HRP transport, but before the decrease, there was a transient facilitatory phase in both colchicine treated and tendonectomized rats. In dystrophy mice, almost twice as much nerve trunk injected HRP was transported as in control mice. This suggests that retrograde transport level increases in some stage of dystrophy.

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PubMed1979

Slow potentials preceding self-paced hand movements in the parietal cortex of monkeys.

In our previous paper, surface negative-deep positive slow potentials were reported to appear prior to self-paced hand movements in the premotor and the forelimb motor cortices of unanesthetized, freely moving monkeys, as recorded with the elctrodes implanted chronically in the cortices. The present study revealed that similar slow potentials were recorded also in the somatosensory cortex in most cases, but infrequently and unmarkedly in area 7, never in area 19.

Animals↗
PubMed1979

Cytometric analysis of small lymphocytes in the bone marrow and lymphatic tissues in neonatally thymectomized and nude mice, with particular reference to differentiation of B-lymphocytes.

In neonatally thymectomized mice and nude mice, small lymphocytes in the bone marrow, Peyer's patches, lymph nodes and spleen were studied qualitatively and quantitatively by electron microscopy. Marrow lymphocytes which are mostly small lymphocytes are classified into dark and light types. The greater proportion of marrow small lymphocytes are of the dark type. Small lymphocytes in Peyer's patches, lymph nodes and spleen are of the light type. The nuclear and cellular sizes of small lymphocytes were estimated stereologically. The nucleus-cell ratio, the volumetric proportions of mitochondria, Golgi apparatus, tubular complexes and dense bodies to the cell body and the proportions of nucleoli and nuclear bodies to the nucleus were also determined. The quantitative results thus obtained suggest that light small lymphocytes in the bone marrow are cytometrically similar to small lymphocytes in Peyer's patches, lymph nodes and spleen and that dark small lymphocytes in the bone marrow are different from other small lymphocytes. The findings are discussed in particular relation to morphological differentiation of B-lymphocytes.

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