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Biomedical subjects

S Sakata

Publications and source records attributed to S Sakata.

At least 325 records · Page 18Linked to original sources
PubMed1979

Localization and verification by synthesis of five antigenic sites of bovine serum albumin.

Recently we have shown that the major antigenic sites of bovine serum albumin exhibit functional equivalence progessively increasing with the time at which antibodies are obtained after the first immunization. Analysis of our recent immunochemical findings and the known covalent structure of bovine serum albumin have enabled us to predict the locations of five antigenic sites of bovine serum albumin. The predicted locations were synthesized, and immunochemical studies with late-course antisera showed them to constitute antigenic sites of native bovine serum albumin.

Animals↗
PubMed1979

Immunochemistry of serum albumin. VI. A dynamic approach to the immunochemical cross reactions of proteins using serum albumins from various species as models.

Antisera against bovine serum albumin were raised in two rabbits. Serial bleedings were obtained at different times after the first immunization, and antisera from these serial bleedings were not mixed but were kept and studied separately. The immunochemical cross-reactions of these antisera with serum albumins from bovine, goat, sheep, porcine, horse, human and chicken were determined by immunoadsorbent studies. These were done by titration so that the values of maximum (plateau) binding by each albumin of radioiodinated antibodies were determined. In each rabbit, the immunochemical cross-reactivity was not static but increased progressievly with time after the first immunization. In the interval 7 days to 398 days the increases in cross-reaction were extremely large. pH dissociation studies revealed that, together with the increase in cross-reactivity of a given albumin with time after immunization, there was a restriction in the antibody heterogeneity towards populations possessing higher affinity. These results provide a rational explanation for the different values of cross-reactivities for a given albumin from different laboratories. The findings are analyzed in relation to the antigenic structure of albumin and their significance in evolutionary studies discussed.

Animals↗
PubMed1979

Genetic control of the immune response to hen's egg-white lysozyme in mice. I. Antibody and T-lymphocyte proliferative responses to the native protein.

We have initiated studies to determine whether the antibody and T-lymphocyte proliferative responses to lysozyme and its antigenic sites is genetically controlled in mice. Mice of the H-2f, H-2k and H-2p were high responders, while haplotypes H-2b, H-2d, H-2r and H-2s were low responders. Studies with recombinants indicated that the immune response is controlled by two H-2I region loci, one being in the I-A subregion and the other may be in the I-C subregions.

Animals↗
PubMed1979

In vitro antiherpesviral activity of 5-alkyl derivatives of 1-beta-D-arabinofuranosyluracil.

Several 5-alkyl derivatives of 1-beta-d-arabinofuranosyluracil (araU) were tested for antiherpesviral activity and inhibitory action on cell growth in human embryonic lung fibroblasts. 1-beta-d-Arabinofuranosylcytosine, 9-beta-d-arabinofuranosyladenine, and 5-iododeoxyuridine (IUdR) were included as reference materials. Among the 5-alkyl derivatives of araU, arabinosylthymine was the most active, followed by 5-ethyl- and 5-propyl-araU. 5-Ethyl-araU was as active as IUdR and more active than 9-beta-d-arabinofuranosyladenine against herpes simplex virus (HSV) type 1 and did not inhibit cell growth at a concentration as high as 1,000 mug/ml. 5-Butyl- and 5-methoxymethyl-araU, as well as araU, exhibited relatively low activity. The araU derivatives tested were as active against HSV WT-34, an isolate from a patient with keratitis, as against HSV type 1. Against an IUdR-resistant isolate, HSV WT-20, arabinosylthymine was less inhibitory than IUdR. Deoxyribonucleic acid synthesis in HSV type 1-infected cells was markedly inhibited by arabinosylthymine, IUdR, and 5-ethyl-araU, whereas cellular deoxyribonucleic acid synthesis in uninfected cells was significantly inhibited by IUdR but not by arabinosylthymine or 5-ethyl-araU.

Arabinofuranosyluracil↗
PubMed1979

[Single photon radioisotope emission computed tomography image using gamma camera (author's transl)].

Single photon radioisotope computed tomography (RCT) images were obtained using the following devices such as conventional gamma camera, data processer for exclusive use of nuclear medicine (C.D.S.-4096), magnetic tape and medium size electronic computer FACOM 230-28S (48K) for multipurposes, which are routinely used for clinical purpose. To reconstruct the RCT image we made absorption correction by geometric mean of opposing counts considering the thickness of source and used the convolution integral method. The reconstructed images of phantom study resolved one centimeter clearly and were very similar to original. The RCT image of patient was acquired by the rotation of patients using the revolving chair and the handmade implement which settles the center of patient's head. Three dimensional informations were obtained by one examination with a gamma camera which collects two dimensional images. When using a gamma camera, therefore, not only a transaxial but an arbitraly RCT image will be important to contribute for diagnosis.

Brain Neoplasms↗
PubMed1978

Enflurane-induced hypotension modifies transmural blood flow distribution in the canine left ventricle.

Coronary and systemic circulations, and contractility and oxygen consumption of the left ventricular myocardium were depressed as arterial enflurane concentration increased in acute experiments with 22 adult mongrel dogs. Uneven transmural blood flow in the left ventricular free wall did not appear and the inner/outer ratio remained near 1.0 until a very deep stage of the anesthesia was attained and as far as diastolic aortic pressure was maintained above 40 mmHg, according to the microsphere injection study. Once diastolic pressure fell below 35--40 mmHg, the ratios started to be reduced significantly. When arterial enflurane content reached 53.0 +/- 2.1 mg/100 ml (mean +/- s.e.), the ratio became 0.84 +/- 0.08 (p less than 0.001), and simultaneously calculated DPTI/TTI ratio also showed a significant redution from the control (0.79 +/- 0.03, p less than 0.001). The I/O and DPTI/TTI ratios, however, did not correlate significantly with each other until very deep enflurane anesthesia was attained. The lower limit of autoregulation of coronary vascular bed was suggested to be near 35--40 mmHg of diastolic aortic pressure during deep enflurane anesthesia in the dog. Among systolic time intervals measured directly during the study, PEP and ICT showed significant negative correlations with Vmax and LV dp/dt max, while LVET neither changed nor correlated significantly with stroke volume or other parameters representing myocardial contractility during the course of enflurane anesthesia.

Animals↗
PubMed1978

[Molecular ageing in bovine plasma albumin I. Exposure of disulfide bonds in the N-B transition (author's transl)].

An accessibility of the disulfide bonds of defatted SH-blocked bovine plasma albumin (BPA) to reduction by dithiothreitol was studied at 4 degree C. Upon reduction SH-blocked BPA acquired one SH per mole in the pH range from 4.0 to 6.0. Above pH 6.5 (the pH range of the N-B transition) an increasing number of the disulfide bonds became susceptible to reduction by dithiothreitol. Chemicals, such as KC1, fatty acid, sodium dodecylsulfate which suppress the structural fluctuation of BPA in the alkaline region decreased the accessibility of the disulfide bonds to reduction. The conversion of buried disulfide bonds into exposed ones is interpreted as being due to conformational changes in the N-B transition (pH 7.0 approximately 9.0).

Animals↗
PubMed1977

Effects of halothane on coronary and systemic circulations, myocardial metabolism and blood flow distribution within the canine heart.

Myocardial metabolism, blood flow distribution within the heart, and coronary and systemic circulations were observed during halothane anesthesia using 15 mongrel dogs. Pao2 and Paco2 were maintained near 100 and 40 torr respectively throughout the study. As arterial halothane content increased, most parameters of systemic circulation were depressed significantly. Coronary blood flow was reduced in parallel with myocardial oxygen consumption (MVo2) (r=+0.89, pless than0.001). Myocardial contractility decreased significantly as anesthesia deepened. MVo2 and myocardial CO2 production were reduced as arterial halothane concentration rose. Arterial-coronary venous difference in blood oxygen content remained unchanged even in deep stage. Lactate and pyruvate were continuously taken up by the myocardium, although the amounts of uptake were reduced as anesthesia progressed. Calculated excess lactate and redox potential did not show any signs of myocardial hypoxia even in deep halothane anesthesia. Among major hemodynamic parameters, left ventricular dp/dt max showed the closest correlation with MVo2. Microsphere injection method was used to observe blood flow distribution within the heart. Halothane did not influence the distribution significantly and I/O ratio of the left ventricular free wall remained near 1.0 during the study.

Animals↗