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Biomedical subjects

T Osawa

Publications and source records attributed to T Osawa.

At least 487 records · Page 27Linked to original sources
PubMed1975

Carbohydrate-binding specificity of the so-called galactose-specific phytohemagglutinins.

The carbohydrate-binding specificities of various so-called galactose-specific phytohemagglutinins were investigated by means of hemagglutination-inhibition assays. As hapten inhibitors, glycopeptides prepared by pronase-digestion of various glycoproteins (porcine submaxillary mucin, bovine submaxillary mucin, and porcine thyroglobulin), and several glycosides of D-galactose and 2-acetamido-2-deoxy-D-galactose were employed. The results indicate that these galactose-specific phytohemagglutinins may recognize the sugar residue penultimate to D-galactose or 2-acetamido-2-deoxy-D-galactose residues of the sugar chain with which they interact, and that they can be classified into three groups based on the type of sugar sequence which they primarily recognize.

Animals↗
PubMed1975

Recurrent spontaneous seizure state induced by prefrontal kindling in senegalese baboons, Papio papio.

In our earlier study of amygdaloid kindling in Papio papio (Pp), the development of partial complex seizure and of focal motor seizure was correlated with bifrontal theta discharge and increasing Rolandic spike discharge respectively and the final stage was characterized by primary generalized convulsive seizure. Since the latter seizure pattern is known to originate from the frontal focus in man, the frontal cortex became suspect in the development of the final stage seizure pattern. Daily prefrontal stimulation showed that Pp can be kindled from this site, culminating in a recurrent spontaneous seizure state identical to that induced by amygdaloid kindling in this species. However, our observation did not support our original assumption regarding the genesis of primary generalized convulsive seizure. Prefrontal and amygdaloid kindling are significantly different with respect to morphology, distribution and propagation of after discharge and interictal spike discharge, and speed and pattern of clinical seizure development. Most intriguingly, inter-ictal behavioral aberration associated with depth EEG changes was observed only in the prefrontal animals and not in the amygdaloid animals.

Action Potentials↗
PubMed1975

Photoaffinity labeling of concanavalin A. Preparation of a concanavalin A derivative with reduced valence.

Concanavalin A (Con A) was labeled with p-azidophenyl alpha-D-mannopyranoside under ultraviolet irradiation and the reaction products were separated by affinity chromatography on Sephadex G-100 at pH 5. One of the Con A derivatives thus obtained was characterized as a monovalent dimer at pH 5 and a divalent tetramer at pH 7 by sedimentation equilibrium and equilibrium dialysis, indicating that this photoaffinity labeling did not alter the quaternary structure of Con A. In agreement with these results, the labeled Con A did not show the capacity to precipitate glycogen at pH 5, but it formed precipitates with glycogen at pH 7. Although its hemagglutinating activity was found to be weaker than that of the native Con A, the dose-response cure of the labeled Con A in the mitogenic stimulation of human peripheral lymphocytes was almost identical to that of the native con A.

Affinity Labels↗
PubMed1975

Purification and characterization of guinea pig lymphotoxin produced by lymph node cells stimulated by phytohemagglutinin.

Guinea pig lymphotoxin (LT) produced by stimulation of lymph node cells with Phaseolus vulgaris phytohemagglutinin was purified approximately 1,000-fold in specific activity by ammonium sulfate fractionation, DEAE-Sephadex column chromatography, and gel filtration on Sephadex G-100. The properties of LT tested at the various stages of purification revealed that the LT was a heat-sensitive, protease-sensitive proteinaceous substance, and its approximate molecular weight was estimated to be 50,000 by means of gel filtration. The most purified fraction (Fr. D) was found to be devoid of the activities of migration inhibitory and mitogenic factors, clearly indicating that these activities are mediated by different substances.

Ammonium Sulfate↗
PubMed1975

Effects of taurine on kindled amygdaloid seizures in rats, cats, and photosensitive baboons.

Acute administration of taurine produced a transient loss of susceptibility to photically induced seizures in photosensitive baboons, but failed to affect kindled amygdaloid convulsions in baboons, rats, and cats. In addition, it was totally ineffective in changing the course of spontaneous status epilepticus in kindled cats. These results suggest that a taurine-deficiency model of epilepsy applies only to certain types of seizure-generating conditions, apparently excluding kindled amygdaloid convulsions.

Amygdala↗
PubMed1975

Effects of tetrahydrocannabinols on kindled amygdaloid seizures and photogenic seizures in Senegalese baboons, Papio papio.

Intraperitoneal injections of delta 8-tetrahydrocannabinol (THC) and delta 9-THC failed to affect myoclonic response to photic stimulation in Senegalese baboons (Papio papio). However, both isomers of THC exerted dose-related antiepileptic effects upon established kindled convulsions provoked by electrical stimulation of amygdala in the same species. Delta 9-THC was more potent than delta 8-THC, in terms of both antiepileptic effects and general toxicity. The antiepileptic effects of the THC isomers appear to be due mainly to the suppression of propagation of the induced afterdischarge to distant cerebral structures, although high doses also seem to suppress afterdischarge at the site of stimulation.

Amygdala↗
PubMed1975

Correlation between mature and immature thymocytes. Immature thymocyte potentiating factor (IMPF) produced by mature thymocytes.

Low-dense mature thymocytes (MT) and high-dense immature thymocytes (IMT) were investigated. Immature thymocyte-potentiating factor (IMPF) was found in the supernatant from MT stimulated by Con A. On the other hand, suppressing activity was present in the supernatant from the unstimulated IMT. IMPF was different from Con A itself. Sephadex G-100 gel chromatography of IMPF revealed that the activity was recovered at the position between bovine serum albumin and ovalbumin.

Animals↗
PubMed1975

Purification and characterization of a hemagglutinin from Arachis hypogeae.

A. hypogaea hemagglutinin was purified by ammonium sulfate fractionation and Sepharose 6 B column chromatography. The homogeneity of the purified hemagglutinin was ascertained by ultracentrifugal analysis and polyacrylamide gel electrophoresis. It has a molecular weight of 106.500 and is a tetramer of a subunit with a molecular weight of 27.000. The purified hemagglutinin agglutinated neuraminidase-treated human erythrocytes regardless of their ABO group type, but did not agglutinate intact erythrocytes. In hapten inhibition assays with simple sugars, the so-called Mäkelä's group 2 sugars, which bear the same configuration of hydroxy groups at C-3 and C-4 as D-galactopyranose, were inhibitors for this hemagglutinin. It does not contain any carbohydrate, in contrast to most phytohemagglutinins except concanavalin A and wheat germ agglutinin.

ABO Blood-Group System↗
PubMed1974

Toxaphene insecticide: a complex biodegradable mixture.

Adsorption and gas-liquid chromatography separate toxaphene into at least 175 polychlorinated 10-carbon compounds including Cl(6), Cl(7), Cl(8), Cl(9), and Cl(10) derivatives. One toxic component is 2,2,5-endo,6-exo,8,9,10-heptachlorobornane. Rats metabolically dechlorinate toxaphene, removing about half of the chlorine from the technical insecticide and from each of seven subfractions of varying composition and toxicity.

Animals↗