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Biomedical subjects

Y Kuroda

Publications and source records attributed to Y Kuroda.

At least 991 records · Page 55Linked to original sources
PubMed1981

Change of cycle AMP level in synaptosomes from cerebral cortex; increase by adenosine derivatives.

The endogenous level of cyclic AMP in incubated synaptosomes from cerebral cortex of guinea pigs was investigated after the addition of various agents to the incubation medium. It appeared that the synaptosomal suspension already contained exogenous adenosine. Preincubation with theophylline or with adenosine deaminase (ADase) decreased both the exogenous level of adenosine and the intrasynaptosomal level of cyclic AMP. The level of cyclic AMP was reincreased by the addition of adenosine agonists, especially 2-chloroadenosine. This increase was antagonized by deoxyadenosine and was not inhibited by dipyridamole. These results suggest that the adenosine derivatives in the synaptic cleft regulate the level of cyclic AMP in nerve terminals through adenosine receptor on the presynaptic membrane. ADP, ATP, dopamine, and histamine also stimulate the formation of cyclic AMP in the ADase-treated synaptosomes.

2-Chloroadenosine↗
PubMed1980

[The method of T4 radioimmunoassay using filter paper blood samples and its application for the early detection of neonatal hypothyroidism (author's transl)].

We examined the method of radioimmunoassay of the Disc T4 (dried blood spot T4) for the purpose of mass screening of neonatal hypothyroidism and tried the parallel assay of T4 and TSH in dried blood spotted on filter paper at the fifth day of life, and we compared the results. By changing the volumes of T4 antibody and T4 antigen solutions, it is possible to measure thyroxine using two discs 3mm in diameter. Disc T4 values obtained in 45 unknown samples by this method were in good correlation with serum T4 values of the same subjects (Y = 0.97X + 0.06). The coefficients of variation were 5.6 to 18.9% in the range of 5.3 to 10.7 micrograms/100ml of Disc T4 (within assay), and 7.9 to 20.8% in the range of 2.4 to 10.3 micrograms/100ml of Disc T4 (between assay). We measured both Disc T4 and Disc TSH of 26,067 newborn infants born between June 1978 and May 1979. Out of 26,067 measurements, four cases of primary hypothyroidism, fourteen cases of TBG deficiency and two cases of transient hypothyroidism were discovered. Out of the four cases of primary hypothyroidism, three showed low Disc T4 (1.3 to 4.0 micrograms/100ml) and high Disc TSH (200 to 240 micromicrons/ml), one showed normal Disc T4 (7.1 micrograms/100ml) and high Disc TSH (30 micromicrons/ml). It was thought the last case might be mild hypothyroidism. In 14 cases of TBG deficiency, Disc T4 was not detectable to 3.4 micrograms/100ml while Disc TSH was within the normal range. In two cases of transient hypothyroidism, Disc T4 measurements showed normal range (6.5, 10.6 micrograms/100ml), and Disc TSH showed high values (41, 120 micromicrons/ml). Therefore, Disc TSH was more sensitive and showed less false positive cases than did Disc T4 for screening hypothyroidism. Although no secondary hypothyroidism existed in the 26,067 measurements, it continues to be important to measure Disc T4 for the discovery of secondary or tertiary hypothyroidism.

Congenital Hypothyroidism↗
PubMed1980

Inhibitory action of adenosine and adenosine analogs on neurotransmission in the olfactory cortex slice of guinea pig - structure-activity relationships.

The postsynaptic potential (PSP) was recorded from thin slices of the olfactory cortex of the guinea pig. Application of adenosine and adenine nucleotides such as 5'-ATP, 5'-ADP and 5'-AMP in the incubation medium, depressed the amplitude of the PSP without altering the presynaptic fiber potential. The other purine and pyrimidine derivatives had no inhibitory effect. The inhibitory action of adenosine and adenine nucleotides on the PSP were manifest at concentrations of 5 microM-1 mM. Adenosine, 5'-ATP, 5'-ADP and 5'-AMP were equipotent in evoking depression of PSPs. Inhibition occurred within 10-20 sec after administration of the agents and the depressant effect disappeared rapidly after the removal of the compounds from the medium. Theophylline reversed and prevented the inhibition produced by adenosine and adenine nucleotides. To test the structure-activity relationships of these compounds, adenosine analogs and adenine nucleotide derivatives were applied to the medium. The 6-aminopurine riboside (adenosine radical) was found to be essential for inhibitory action on the PSP. Among adenosine analogs, the presence of at least one hydrogen atom in the amino group at the 6-position of the purine, and the OH group at the 2'-position of the ribose was essential for inhibitory activity.

Action Potentials↗
PubMed1980

Effect of alteration of pheripheral blood flow on the central circulation in man during supine cycling in different ambient temperatures.

Whether the alteration of peripheral circulation caused by changing ambient temperature (Ta) affects central circulatory changes in man during supine cycling was investigated in four well-trained men, who exercised at two levels (117.7 or 176.6 W). Exercise metabolic rate (VO2) in cold (0 degree C or 10 degrees C) was the same as it was at 20 degrees C, whereas the cardiac output (CO; CO2 rebreathing technique) and heart rate were significantly lower (e.g.,176.6 W at 0 degree C, both p < 0.01). In heat (30 degrees C or 40 degrees C), the VO2 reduced with falling CO and mean arterial blood pressure from those at 20 degrees C (e.g., 176.6 W at 40 degrees C, all cases p < 0.01), whereas the peak post-exercise calf blood (CBFp) increased (p < 0.01). The VO2 and stroke volume (SV) were inversely proportional to the ratio of CBFp to CO/kg body weight (CBFp/CO) (r > -0.78, p < 0.001). Total peripheral resistance (TPR) was related to arteriovenous oxygen difference (A-VO2 difference) (r > 0.78, p < 0.001). The TPR and A-VO2 difference decreased as Ta rose, while CBFp/CO was almost the same. As CBFp/CO had exceeded 50 and further progressed, however, the two parameters elevated until the same level as that at 0 degree C. The present results suggest that during moderately prolonged (16--60 min) supine cycling in different Ta's the central circulatory changes are mainly affected by the altered peripheral blood flow in competing between skin and muscle for blood flow.

Blood Circulation↗
PubMed1980

Unexpected problems of external choledochoduodenostomy. Fiberscopic examination in 15 patients.

Fiberscopic examination was carried out to investigate the condition of the stoma and bile duct and to assess the postoperative effects of the procedure on the upper gastrointestinal tract in 15 patients who received external side-to-side choledochoduodenostomy. The stoma remained patent, with a round or oval shape, in all 15 patients. Residual sutures were found at the stoma in 4 of 15 patients, 3 of whom had inflamed stomal mucosa. Food debris was found in the blind segment in four of seven patients. but all 4 had large stomas. In three patients food debris was floating and easily discharged through a stoma. In the other patient much food debris had accumulated and was firmly attached to the mucosal surface. Gastroduodenal lesions were noted in 9 of 15 patients: redness at the antrum in 3, multiple erosions at the antrum in 2, gastric ulcer in 1, redness at the bulbus in 1 and duodenal ulcer in 2. Bile reflux into the stomach was found in 9 of 15 patients, 5 of whom had gastric lesions, and duodenal mucosa was constantly exposed to bile in all 15 patients.

Adult↗
PubMed1980

Concanavalin A inhibits the development of experimental allergic encephalomyelitis in guinea pigs.

The effect of concanavalin A (Con A) on experimental allergic encephalomyelitis (EAE) was assessed in guinea pigs with a various time, dose and route schedule. EAE was significantly suppressed when 5 mg of Con A was injected in the sensitizing injection sites within 3 days before or after sensitization with bovine spinal cord in complete Freund's adjuvant. The EAE-suppressive activity of Con A was shown by significant reductions in incidence and severity of EAE, a delayed onset of EAE and low mortality. The proliferative response of draining lymph node cells (LNC) to myelin basic protein (BP), the growth of the draining lymph nodes (LN) and the proliferation of active rosette-forming T cells in the draining LN were all significantly suppressed in Con A-treated animals than those of unsuppressed animals. The depressed LNC reactivity to BP in Con A-treated animals was not increased when nylon wool adherent cells were removed, whereas there was a significant increase in unsuppressed animals. These results suggest that Con A suppressed EAE by inhibiting the proliferation of BP-sensitized T cells in the draining LN and that the interaction between T cell subsets could exert an inhibitory effect on EAE.

Animals↗
PubMed1980

Effect of bisulfite on cell-to-substratum adhesion of Chinese hamster cells in culture.

The direct action of bisulfite on cultured mammalian cells was studied. Chinese hamster cells precultured in plastic dishes for 2 hr were treated for 1 hr with balanced salt solutions containing bisulfite. Then they were washed, and their colony-forming ability in normal medium was determined. Significant decrease in the colony formation was observed upon treatment with bisulfite solutions over 30 mM concentration. The decrease in the colony number was found to be due to detachment of the cells from the dishes during treatment with bisulfite and subsequent washing. When the preculture time was prolonged to allow the cells to adhere to the dish more firmly, the effect of bisulfite was no longer observable. These results indicate that factors required for cell-substratum adhesion are susceptible to bisulfite.

Animals↗
PubMed1980

FR-900130, a novel amino acid antibiotic. I. Discovery, taxonomy, isolation, and properties.

A new antibiotic, designated FR-900130, has been discovered in the culture filtrate of Streptomyces. The producing organism has been identified as Streptomyces catenulae. The antibiotic was purified by adsorption onto Duolite C-20, passage through Amberlite IRC-50, final purification and desalting on Sephadex G-25. It shows antimicrobial activity against Gram-positive bacteria and synergy with D-cycloserine. The antibiotic is very labile in alkaline solution above pH 8.0 and decomposed during lyophilization or solvent precipitation. It was converted to an acetyl derivative and the biological properties of the derivative were examined.

Acetylation↗