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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 1,729 records · Page 96Linked to original sources
PubMed1980

Receptors for IgG Fc and complement in the mammalian aorta.

The presence of IgG Fc receptors in the tissue sections of aorta and aortic valves of man, ox and pig was demonstrated by means of hemadsorption of human and rabbit IgG antibody sensitized erythrocytes to these sections. C3b receptors in the tissue sections of aortic valves of these three mammals were also demonstrated by using sheep erythrocytes sensitized with rabbit IgM antibody which bound murine complement. 8 of 13 systemic lupus erythematosus sera and 2 of 19 other collagen disease sera were shown to be able to inhibit the adsorption of rabbit IgG antibody sensitized erythrocytes to the human aortic sections upon preincubation of the tissues with the pathologic sera. The amount of immune complexes in the 'inhibition-positive' sera was significantly higher than that in the negative sera.

Adult↗
PubMed1980

Detection of regional cardiac wall motion abnormalities in myocardial infarction by cardiac wall kymography.

The new system of cardiac wall kymography was proposed based on the results with our modified device. The cardiac wall motion kymography taken from a portion of the precordial area was examined for its ability to detect wall motion abnormalities. Furthermore, the 3 dimensional graphic display of the cardiac wall kymogram map was attempted by computer. This new approach looks promising because of the enhanced ability to recognize cardiac wall motion abnormalities in myocardial infarction.

Heart↗
PubMed1980

Liver 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity in pyridoxine-deficient rats.

The activities of 3-hydroxy-3-methylglutaryl-CoA reductase [EC 1.1.1.34] in the livers of pyridoxine-deficient and control rats were compared. The reductase activity, which is known to show a circadian rhythm, was about twice as high in pyridoxine-deficient rats during both the light and dark periods. After administration of cycloheximide the rate of decrease in reductase activity was similar in pyridoxine-deficient and control rats. The Km values from the two groups for DL-DMH-CoA, the heat stabilitied and the microsomal lipid compositions were also similar. The effects of cytosolic activator and inactivator proteins on the reductase activities were also similar. These results show that the increased activity in pyridoxine-deficient rats is due to increased enzyme synthesis or increased specific activity induced by some unknown mechanism, but not to change in the state of phosphorylation of the enzyme.

Animals↗
PubMed1980

Effects of various pharmacologic agents on allergic inflammation of the eye. The roles of chemical mediators in ocular inflammation.

Effects of pharmacologic agents on experimental ocular inflammation induced by reverse passive Arthus reactions were investigated by a slit-lamp technique utilizing fluorescein-labeled rabbet serum albumin as an indicator. Cobra venom factor completely eliminated inflammatory responses, indicating that the complement system is a trigger for this type of ocular inflammation. Antihistamines mainly suppressed the early vascular response. Reserpine and indomethacin remarkably inhibited the increase of the permeability of the blood-aqueous barrier over the first 5 hr. Epinephrine and steroid hormone were also effective. Neither diethylcarbamazine nor isonicotinic acid showed effects on the permeability changes induced in this type of inflammation.

Animals↗
PubMed1980

[Primary endodermal sinus tumor of the fourth ventricle (author's transl)].

A case, a 18-year-old male, of an endodermal sinus tumor (yolk sac tumor) in the fourth ventricle, was reported. The patient had a month history of headache, vomiting and gait disturbance prior to the hospitalization, when he admitted to our service he was in lethargic condition with left cerebellar ataxia and horizontal nystagmus. Lumbar tap revealed clear CSF under normal pressure of 110 mm H2O with the CSF protein of 432.5 mg/dl and cell count of 147/3. The vertebral angiography demonstrated space occupying lesion in the posterior fossa. Plain CT demonstrated only disappearance of the fourth ventricle and slightly dilated bilateral ventricles and third ventricle. However diffuse high density area around the fourth ventricle was demonstrated and the wall of bilateral anterior horn was slightly enhanced, after injection of contrast media. There was no other abnormal findings around the pineal region. Suboccipital craniectomy was performed and the tumor was totally removed macroscopically. The tumor was situated in th floor of the fourth ventricle and infiltrated into the fourth ventricular wall and th adjacent cerebellar tissue. The tumor was with soft, greyish color and extremely vascular. Histologically the tumor was diagnosed as endodermal sinus tumor according to Teilum's classification. There were stellate cells arranged in a loose with vacuolated network which formed cystic cavities and a complicated network of honeycomb appearance with a system of communicating cavities and channels. Various size of intra- and extracellular PAS-positive hyaline globules were also seen. Glomerular-like structure (Schiller-Duval body) was not observed. Immunoperoxidase study clearly demonstrated the presence of intra- and extracytoplasmic alpha-fetoprotein granules in the tumor tissue. The amount of the serum alpha-fetoprotein, measured by radioimmunoassay, showed 400 ng/ml. After irradiation in the posterior fossa (5000 rad) the patient was discharged. Three months later, follow up CT demonstrated small high density area in the anterior horn of the left lateral ventricle, so he was rehospitalised. Irradiation in the whole brain was again administered. The tumor was very radiosensitive. CT, after 800 rad, demonstrated complete disappearance of the tumor. After irradiation totally (3000 rad), he discharged with left cerebellar ataxia.

Adolescent↗
PubMed1980

The continuous and quantitative observation of permeability changes of the blood-aqueous barrier in allergic inflammation of the eye.

Permeability changes of the blood-aqueous barrier were studied in the eyes of rabbits subjected to immunologic inflammation. The changes were investigated by slit-lamp microphotometers. The leakage of fluorescein-labeled rabbit serum albumin into the anterior chamber was observed in eyes inflamed by reverse passive Arthus reactions. The permeability of the blood-aqueous barrier changed in biphasic pattern in allergic inflammations; the first phase began 5 min after the antigen challenge and lasted for 1 hr, followed by the late phase at which the dye concentration reached a peak 2 hr after the challenge and then gradually decreased.

Animals↗
PubMed1980

Synthesis and mutagenicity of 4-(N-butylnitrosamino)-4-hydroxybutyric acid lactone, a possible activated metabolite of the proximate bladder carcinogen N-butyl-N-(3-carboxypropyl)nitrosamine.

4-(N-Butylnitrosamino)-4-hydroxybutyric acid lactone (BBAL) was synthesized as a possible intermediate produced by metabolic activation of a selective bladder carcinogen, N-butyl-N-(3-carboxypropyl)nitrosamine. BBAL was stable in neutral sodium phosphate buffer (ionic strength, 0.2), having a half-life of more than 30 hr at 25 degrees. The mutagenic effects of BBAL were tested with the use of Salmonella typhimurium TA1535 and Escherichia coli B/rWP2-try-, WP2-try-hcr-, and Sd4. The gene-damaging effects were assayed by repair tests with Bacillus subtilis H17 (rec+) and M45 (rec-). BBAL showed potent effects in the mutation and repair tests on all the strains tested without activation. A possibility is suggested for the metabolic activation of N-butyl-N-(3-carboxypropyl)nitrosamine to BBAL by alpha-hydroxylation at the site of the 3-carboxypropyl chain followed by lactonization in target tissues prior to interaction with macromolecules to lead to carcinogenesis.

Bacillus subtilis↗
PubMed1980

Mutagenic and DNA-damaging effects of N-(omega-acetoxyalkyl and omega-methoxycarbonylalkyl)-N-(alpha-acetoxyalkyl)nitrosamines, models for metabolically activated N,N-dialkylnitrosamines with an omega-functional group.

Mutagenic and DNA-damaging effects of a series of N,N-dialkylnitrosamines having an alpha-acetoxy group together with an alpha-acetoxy or an omega-methoxycarbonyl group were tested in Salmonella typhimurium, Escherichia coli, and Bacillus subtilis without metabolic activation. The compounds comprised each of 3 N-(omega-acetoxyalkyl)-N-(acetoxymethyl)nitrosamines, N-(omega-methoxycarbonylalkyl)-N-(acetoxymethyl)nitrosamines, and N-(omega-methoxycarbonylalkyl)-N-(alpha-acetoxybutyl)nitrosamines. All the compounds gave positive results in these mutagenicity and repair tests. No definite differences were observed in the mutagenic and DNA-damaging effects between the model compounds derived from the carcinogenic compounds and those derived from the non-carcinogenic counterparts. The strongest mutagenic activity was observed so far with N-(2-methoxycarbonylethyl)-N-(l-acetoxybutyl)nitrosamine in all of the four bacterial strains.

Bacillus subtilis↗
PubMed1980

Formation, deoxygenation and mutagenicity of alpha-hydroperoxydialkylnitrosamines.

N-Nitroso-N-alkyl-alpha-hydroperoxyalkylamines were prepared either by treatment of N-nitroso-N-alkyl-alpha-acetoxyalkylamines with hydrogen peroxide in acetic acid or by oxygenation of lithiated N-nitrosodialkylamines with oxygen. They were strongly mutagenic towards S. typhimurium TA1535 and E. coli WP2 strains without metabolic activation. Treatment of the alpha-hydroperoxy compounds with deoxygenating agents, such as sodium bisulfite, gave the alpha-hydroxynitrosamine, which could be isolated in aprotic solvents and characterized. The alpha-hydroperoxy compounds can possibly be formed from N-nitrosodialkylamines by biochemical and environmental routes and can serve as precursors for the alpha-hydroxynitrosamines.

Chemical Phenomena↗