Search PubMed⌕ Search

Biomedical subjects

A Nishi

Publications and source records attributed to A Nishi.

At least 73 records · Page 4Linked to original sources
PubMed1985

[3H]5-hydroxytryptamine binding to reconstituted fraction with sulphatides, phosphatidylserine and phosphatidylinositol.

As a first step toward the examination of the involvement of sulphatides, phosphatidylserine and phosphatidylinositol in 5-HT receptor mechanisms, we performed [3H]5-HT binding experiments on the various reconstituted fractions with these acidic lipids. A binding assay of [3H]5-HT to these fractions was carried out by Sephadex LH20 column chromatography. Among various reconstituted fractions, only the reconstitution system with the three acidic lipids exhibited a saturable [3H]5-HT binding capacity, whereas no binding was seen with [3H]-spiperone. When the binding of [3H]5-HT to this fraction was plotted as a function of the ligand concentration, a multiple binding mode with three classes of binding components (or sites) was observed. Furthermore, the double reciprocal plot indicated that this reconstitution system had three apparent KD values of 4.7, 15 and 59 nM. The displacement studies with various compounds indicated that only a few 5-HT agonists (5-methoxytryptamine and tryptamine) and neurotransmitters (DA and ACh) inhibited the [3H]5-HT binding to this fraction, but 5-HT antagonists, LSD analogues and neuroleptics had no effect. Moreover, GTP, GDP and Gpp(NH)p clearly inhibited the [3H]5-HT binding in spite of their weak potencies, while GMP did not have any effect.

Animals↗
PubMed1984

Differentiation response of Physarum polycephalum to macrocysts at various times in nuclear cycle.

Macrocyst (spherule) formation was induced in synchronized suspension cultures of microplasmodia of Physarum polycephalum under conditions where DNA synthesis was inhibited. Plasmodia in early G2 phase of nuclear cycle were able to differentiate to spherules in the presence of an inhibitor of DNA synthesis, whereas those in late G2 phase required another round of DNA replication before they could enter into the spherulation process. These facts suggest that commitment to DNA synthesis occurred about halfway through G2 phase. The idea was also supported by the results of autoradiographic study in which spherulating plasmodia were fed with radioactive thymidine and labelled plasmodia were scored at the terminal differentiation stage.

Aphidicolin↗
PubMed1981

Hexosamine metabolism during spherule formation in Physarum polycephalum.

Hexosamine metabolism in relation to the spherule-wall synthesis in Physarum polycephalum was studied by the incorporation of labeled sugar into the wall and intermediary compounds in the biosynthesis of wall polysaccharide. The incorporation of [14C]galactosamine into the wall material occurred after a lag period of about 10 h in an induction medium. Nucleotides and sugar phosphates in the acid-soluble fraction of spherulating plasmodia were analyzed by column chromatography on Dowex 1-X8 (formate). The primary labeled products formed in the spherulating plasmodia after incubation with [14C]galactosamine were galactosamine 1-phosphate, UDP-galactosamine, N-acetylhexosamine 6-phosphate and UDP-N-acetylhexosamine. Spherulation was insensitive to polyoxin D, while it was completely blocked by cycloheximide. The activity of galactokinase and galactose-1-phosphate uridyltransferase increased 4--5-fold during the spherulation.

Anti-Bacterial Agents↗
PubMed1979

Morphological studies on liver lymphatics.

Form, distribution and structure of liver lymphatics were studied in pig, calf, kid, dog, rabbit and human using both light and electron microscopes. The relation of the lymphatics to both blood vessel and connective tissue was the same throughout the material. The lymphatic capillaries were supported by a lattice of the coarse bundles, composed of collagenous fibers. The endothelial cells of the lymphatic capillaries lying in the meshes of the lattice showed a marked change in the volume and a phagocytotic activity. The results were discussed in relation to the function.

Animals↗
PubMed1975

Protein kinase in cultured plant cells.

A protein kinase (EC 2.7.1.37) which phosphorylates histones was purified partially from the soluble fractions of cultured plant cells. The optimum pH was 7.5 to 9.0. The activity wasnot stimulated by exogeneous cyclic AMP. It was thermolabile and completely dependent on the presence of Mg2+ or Mn2+ for activity. p-Chloromercuribenzoate inactivated this enzyme and this inactivation was overcome by mercaptoethanol.

Cyclic AMP↗
PubMed1965

Protein turnover in the cell cycle of Escherichia coli.

Nishi, Arasuke (University of Tokyo, Tokyo, Japan), and Tokio Kogoma. Protein turnover in the cell cycle of Escherichia coli. J. Bacteriol. 90:884-890. 1965.-Protein metabolism and enzyme formation throughout the cell cycle were investigated in synchronized cultures of Escherichia coli. The cells showed a temporary cessation of the net increase of bulk protein and of constitutive beta-galactosidase activity during the division period. By contrast, when tested by short-term experiments performed with cells at different growth stages, the bacteria displayed a constant incorporation of labeled protein precursors into the protein fraction, even during the fission period. Similar results were obtained with respect to the capacities for induced enzyme formation. On the other hand, when the cells were previously labeled and then subjected to synchronization in a nonradioactive medium, the radioactivity of the protein fraction decreased temporarily by nearly 10% during the fission period and then regained its previous level at the beginning of the ensuing phase of growth. This indicates that the products of partial degradation of protein were again utilized for protein synthesis in the next cell cycle. It was concluded that the temporary lagging of net increase of bulk protein may be due to the partial breakdown of protein occurring during the fission period.

Bacterial Proteins↗