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Biomedical subjects

H Ochiai

Publications and source records attributed to H Ochiai.

At least 253 records · Page 14Linked to original sources
PubMed1981

Study on the single radial complement fixation (SRC-fix) test.

We examined whether the single radial complement fixation (SRC-fix) test is applicable to serological diagnosis of viruses. The viruses used for the examination were influenza A and herpes simplex viruses. SRC-fix test was shown to be a very simple method, that is, serum samples were added to agarose plate A containing complement and CF antigen, and agarose plate B, containing antibody-coated erythrocytes, was layered on top of the plate A to form zone areas of unlysed cells. CF titres of the samples were determined from the square of the zone diameter of unlysed cells. Thus SRC-fix test is suggested as a new method for diagnosis of viral diseases.

Antibodies, Viral↗
PubMed1981

Developmentally regulated glycoprotein alterations in Dictyostelium discoideum.

We have studied the changes in glycoprotein patterns on the surface of Dictyostelium discoideum cells during development on a membrane filter and in suspension culture. Cell-surface carbohydrates were detected by a periodate-[3H]borohydride method. The appearance and the increase of some glycoproteins during the early developmental stage on a membrane filter were induced 6 h after the onset of starvation. In suspension culture the same proteins appeared about 2 h earlier and less copies per cell were made. Some glycoproteins present in growth-phase cells, especially with high molecular weights, partially disappear during development on a membrane filter. However, the latter changes were not observed in suspension culture. Pulses of cAMP, which generally accelerate cell development, induced only the appearance of one glycoprotein. We conclude that the changes in patterns of plasma membrane glycoproteins during early development are regulated by several factors; starvation, pulses of cAMP, cell-cell contact and transfer onto a membrane filter.

Cell Membrane↗
PubMed1981

Drastic changes in accumulation and synthesis of plasma-membrane proteins during aggregation of Dictyostelium discoideum.

Protein compositions of plasma membranes of Dictyostelium discoideum and their developmental changes during aggregation were analyzed by two-dimensional polyacrylamide gel electrophoresis. More than 150 polypeptide species could be detected with the growth-phase cells by staining. Most of them (about 120 spots) were conserved during aggregation, although their relative intensities of staining changes. On the initiation of cell differentiation, new polypeptides were accumulated on the plasma membrane and at least 110 new polypeptides were detected at the late-aggregation stage. This accumulation of new components was completely inhibited when the growth-phase cells were incubated in a liquid medium containing 5 mM EDTA. Studies on protein synthesis suggested that the accumulation and appearance of the new protein components was due to de novo synthesis. Pulse-label experiments with [35S]methionine showed that out of 200 proteins detected during aggregation, about 90 proteins showed various stage-specific patterns of synthesis and the rest were synthesized consistently. Actin and discoidin present in the plasma membrane were identified by reference to purified actin and discoidin. Actin synthesized de novo accumulated progressively on the plasma membrane during aggregation. Discoidin also accumulated on the plasma membrane, but a large amount was also recovered in a cytoplasmic soluble fraction. Discoidin I was separated into two spots with different pI values on a two-dimensional gel.

Cell Membrane↗
PubMed1980

"Living electrode" as a long-lived photoconverter for biophotolysis of water.

Living blue-green algae (Mastigocladus laminosus), immobilized on an SnO(2) optically transparent electrode with calcium alginate, functioned as an anodic photoelectrode on continuous illumination for periods of time adequate for use in a conventional electrochemical cell. This "living electrode" shows promise of use as a long-lived photoconverter of solar radiant energy to electric energy and as a suitable replacement for unstable chloroplast systems.

Journal Article↗
PubMed1980

Surface labeling of membrane glycoproteins and their drastic changes during development of Dictyostelium discoideum.

Surface glycoproteins on plasma membranes from Dictyostelium discoideum were labeled by sodium metaperiodate oxidation and sodium boro[3H]hydride reduction. The amount of incorporation of tritium from NaB3H4 reached a plateau after 10 min at a periodate concentration of 20 mM. The density analysis carried out by sucrose density-gradient centrifugation showed that the plasma membranes were selectively labeled by this technique. About 84% of the radioactivity incorporated was released by hydrolysis with 0.25 M H2SO4 for 3 h at 100 degrees C. The released materials were eluted at a bed volume after chromatography using a Sephadex G-50 column. From the paper chromatographic analysis of the eluate, four radioactive spots were detected. Two of them were glycerol and glyceraldehyde and the other two spots seemed to be oligosaccharides. Using the above method, the plasma membranes from aggregation-phase cells were labeled four times more than those from growth-phase cells. The labeled plasma membrane fraction during the aggregation phase was separated into at least 39 distinct glycoprotein bands on a one-dimensional dodecylsulfate/polyacrylamide gel. Six of the 39 bands increased markedly in density and two new bands appeared. In contrast, four bands decreased in density in the aggregation phase. Using this method, the surface glycoproteins can be analyzed directly be gel electrophoresis of the lysate of labeled whole cells without preparing the plasma membranes. Changes during development of glycoproteins on outer cell surfaces were also confirmed by O'Farrell's method of two-dimensional polyacrylamide gel electrophoresis. Utilizing this technique, glycoproteins on plasma membranes of D. discoideum were separated into 63 individual spots; 45 of these 63 spots changed during the early developmental course of D. discoideum. This is in contrast to the slight change in the soluble and membrane proteins during this phase. This fact also suggests that the glycoproteins have important roles in the process of aggregation.

Cell Membrane↗
PubMed1977

Fine structure of ependymal cells in the median eminence of the frog and mouse revealed by freeze-etching.

Freeze-etched preparations of the ventricular surfaces of ependymal cells clearly reveal the presence of pinocytotic vesicles opening into the third ventricle and large vacuoles formed by broad cell projections. The density of the vesicular openings is approximately 20 per micron2. The ependymal cells in the median eminence of the frog are adjoined by tight junctions comprised of five to eight interconnected junctional strands, whereas near the median eminence in the mouse only one to two such strands form the tight junction of the ependymal cells. Gap junctions between the adjacent ependymal cells are detected near the median eminence in the mouse but not in the frog.

Animals↗
PubMed1977

Cytological evidence for different types of cerebrospinal fluid-contacting subependymal cells in the preoptic and infundibular recesses of the frog.

Blue-green fluorescent subependymal cells with intraventricular processes were shown by the fluorescent histochemical method to be distributed from the preoptic recess to the infundibular recess of the frog hypothalamus. Electron microscopy revealed at least two types of CSF-contacting subependymal cells, type 1 containing large dense granules (about 100-200 nm in diameter) and type 2 containing small dense core vesicles (about 60-100 nm in diameter). Subsequent to fixation in permanganate solution, the small dense core vesicles in type 2 cells reacted with the fixative and consistently showed a dense content. However, the large granules in type 1 cells were mostly pale or less dense after this fixation. Two hours after intraventricular injection of 3H-dopamine, a large number of silver grains appeared only in the cytoplasm of intraventricular processes possessing dense core vesicles (type 2 cells). A few grains were also found in the perikarya. It is concluded that type 2 cells are catecholamine-storing cells. It is suggested that type 1 cells in the infundibular recess are peptidergic neurons which may secrete some hypothalamic regulating hormones of the anterior pituitary. Most of these cells in the preoptic recess belong to the neurosecretory cells of the preoptic nucleus, while some cells probably function similarly to those in the infundibular recess.

Animals↗
PubMed1977

Resistance mechanism of chloramphenicol in Streptococcus haemolyticus, Streptococcus pneumoniae and Streptococcus faecalis.

The chloramphenicol resistance of Streptococcus haemolyticus, Streptococcus pneumoniae and Streptococcus faecalis isolated from clinical materials was proved to be due to an inactivating enzyme produced by these bacteria. The inactivated products of chloramphenicol were identified as 1-acetoxy, 3-acetoxy and 1,3-diacetoxy derivatives by thin-layer chromatography and infrared spectroscopy. The responsible enzyme was thus confirmed to be chloramphenicol acetyltransferase. The enzyme was inducible. It was partially purified by ammonium sulfate precipitation, DEAE-cellulose chromatography and gel filtration on Sephadex G-150. The enzymes obtained from S. haemolyticus, S. pneumoniae and S. faecalis have been compared with the conclusion that they are identical with respect to molecular weight (approximately 75,000-80,000), optimum pH and heat stability.

Acetyltransferases↗
PubMed1977

Fine-structural and functional aspects of the cerebrospinal fluid-contacting subependymal cells in the anuran hypothalamus.

Cytological characteristics of the cerebrospinal fluid (CSF)-contacting subependymal cells in the frog hypothalamus were investigated to decide whether they should be classified as neurons, sensory cells or secretory (endocrine) cells. The CSF-contacting subependymal cells exhibited morphological characteristics similar to neurons or sensory cells, which are usually supplied with axo-somatic and -dendoritic synapses from other neurons and possess somato-dendritic synapses to other neurons. Furthermore, they were provided with so-called sensory cilia. The CSF-contacting subependymal cells also exhibited several cytological secretory cell characteristics: the presence of numerous secretory granules, well-developed granular endoplasmic reticulum and Golgi apparatus in the perikaryon as well as intraventricular processes, and some figures which may be regarded as microapocrine or diacrine secretions of the secretory granules. Furthermore, the CSF-contacting subependymal cells probably sent basal cell processes to the area around the blood vessels in the neurohypophysis and, perhaps, in the infundibulum. It seemed likely that CSF-contacting subependymal cells had two or three functions of a paraneuronic nature. They were sensory to chemical or physical stimuli frmones just as endocrine cells do.

Animals↗
PubMed1976

[Bacteriological studies on doxycycline (Bonnamycin 'Cipan') (author's transl)].

Bonnamycin which is a new tetracycline group antibiotic isolated from a variant strain of Streptomyces rimosus and is identified chemically as doxycycline was investigated, comparing with tetracycline. The results are as follows: (1) In in vitro studies of anti-bacterial spectrum, doxycycline is widely effective against standard strains kept in our department. (2) The distribution of susceptibility of 75 Staphylococci, 62 Salmonella and 64 Shigella strains isolated from clinical materials was similar to that of tetracycline. (3) As to the therapeutic experiment in acute infection of Klebsiella pneumoniae in mice, the drugs were equally effective and the ED50 was both 70.8 mcg. (4) Doxycycline administrated orally or subcutaneously in rats was distributed in kidneys, livers, lungs and spleens at relatively high concentration among organs.

Acute Disease↗