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Biomedical subjects

T Yasuda

Publications and source records attributed to T Yasuda.

At least 919 records · Page 51Linked to original sources
PubMed1981

Asymmetric division of lymphoid cells of the thymus of embryonic guinea-pigs. A cell kinetic study.

Cell division of thymus lymphoid cells from 30- to 60-day-old embryonic guinea-pigs, as well as young adults was investigated on cell smears stained with Giemsa. Asymmetrically dividing cells were found in the developmental stage of thymocytes. At the telophase of such cells, the cytoplasma of one of two immature daughter cells was apparently larger in amount than that of the counterpart cell. When 40-day embryonic lymphoid cells were examined, most of the asymmetrically dividing cells at telophase belonged to the larger cell population (mean diameter 15.7 micrometer). The mean diameters of the larger and smaller immature daughter cells of these dividing cells were estimated as 12.0 and 9.2 micrometer, respectively. Ultrastructural study also revealed a lymphoid cell which was under-going in situ apparent symmetric division at telophase. One of two immature daughter cells alone possessed a large cytoplasmic protrusion with few organella. The frequence of asymmetric division calculated by a rough estimation was around 10% of the total cell division between days 30 and 40 of embryonic development, and decreased thereafter. During this developmental period, thymic lymphoid cells were shown to progressively transform into smaller cells. A scheme regarding the mode of thymocyte proliferation during the embryonic period is proposed. and the biological meaning of the present phenomenon is discussed.

Animals↗
PubMed1981

Myocardial imaging with 9-[Te-123m]telluraheptadecanoic acid.

The distribution of radioactivity in the myocardium of rats and dogs infarcted by ligation of the left anterior coronary artery has been determined after intravenous injection of 9-[Te-123m]telluraheptadecanoic acid (Te-123m HDA]. In rats the normal myocardium concentrated radioactivity (3.7% +/- 0.28 injected dose/g) to nearly three times that in the zones of infarction (1.12% +/- 0.18 dose/g0. The focal defects detected in the gamma-camera images of rats and dogs correspond well with areas of infarction identified in the excised hearts by staining with triphenyltetrazolium chloride. The distribution of radioactivity from Te- 123m HDA in dog hearts sectioned at autopsy showed a linear correlation (r = 0.94) with blood flow as determined with scandium-46-labeled microspheres.

Animals↗
PubMed1980

Safe limit of hemodilution in cardiopulmonary bypass -comparative analysis between cyanotic and acyanotic congenital heart disease.

A safe limit of hemodilution in cardiopulmonary bypass (CPB) for open heart surgery was investigated by analyzing of the perfusion results of 100 patients with tetralogy of Fallot (TOF) and ventricular septal defect (VSD). The higher perfusion flow was necessary to compensate for the reduced oxygen carrying capacity and to maintain adequate arterial pressure in proportion to the increase in hemodilution. Once the dilution ratio reached over 40% in TOF and 50% in VSD, however, adequate oxygen transfer and stable hemodynamic conditions could not be maintained. The former was due to inadequate oxygen delivery and the latter to an impaired venous return. In these cases, various complications caused by residual diluent in the body space despite of extensive diuretic therapy occurred immediately postop. The safe limit of hemodilution is 50%. However, that of cyanotic disease, even in the presence of remarkable polycythemia, must be limited to less than 40%.

Cardiopulmonary Bypass↗
PubMed1980

Isolation and some properties of a new fiber-forming protein from Tetrahymena pyriformis.

Isolation and characterization of a fibrous protein component which might be associated with contractile ring of a dividing Tetrahymena cell were attempted by making use of coprecipitation of the protein with rabbit skeletal muscle myosin. The protein was purified to homogeneity by ammonium sulfate fractionation between 40--70% saturation and column chromatography of Sephadex G-200, starting from KCl-extract of Tetrahymena acetone powder. Its molecular weight was calculated to be 38,000, based on the electrophoretic mobility in sodium dodecyl sulfate (SDS)-polyacrylamide gel, whereas molecular weight of its native state was determined to be 140,000 by gel filtration on Sephadex G-200, and its sedimentation coefficient was about 9S as estimated by sucrose density gradient centrifugation. The latter was a particle of 7.7 nm in diameter under an electron microscope and supposed to be a tetramer of the 38,000-dalton protein. The protein is considered to be a new, unique protein, since it is definitely different from the ubiquitous non-muscle actin in molecular weight, polymerizability in KCl solution and amino acid composition, and it also different from tropomyosin and tubulin in immunological characteristics and amino acid composition.

Actins↗
PubMed1980

Localization of a new fiber-forming protein within Tetrahymena pyriformis.

As a step to study the biological function of a new protein, fiber-forming protein-38,000 (FFP-38), which was previously isolated from Tetrahymena pyriformis, its intracellular localization was investigated by using antiserum specific for FFP-38. Double immunodiffusion tests revealed that the anti-FFP-38 serum reacted with the protein(s) in isolated organelles such as oral apparatus, pellicles and mitochondria, to give rise to a precipitin line confluent with the line formed between the antiserum and the FFP-38. Furthermore, indirect fluorescent antibody staining showed that fluorescence was intensely localized in the oral apparatus and faintly distributed throughout the cytoplasm. In particular, distinct fluorescence was found along the division furrow of dividing Tetrahymena.

Animals↗
PubMed1980

In vitro filament formation of a new fiber-forming protein from Tetrahymena pyriformis.

Using a 38,000-dalton protein (FFP-38) purified from Tetrahymena acetone powder, we have succeeded in the polymerization of this protein into 14-nm filaments. The polymerization was initiated by incubating the purified FFP-38 fraction in a buffer containing 5 mM Mes (2-(N-Morpholino)ethanesulfonic acid), 50 mM KCl, 1.2 mM CaCl2, 0.6 mM ATP, pH 6.6, and by shifting the incubation temperature from 0 degrees C to 37 degrees C. The 14-nm filament is considered to consist of 7-nm globular subunits regularly arranged into 2 start, helical strands with 4 subunits per turn. The subunit may correspond to 9S tetramer of FFP-38, a native form of FFP-38. Since the subunit arrangement and subunit protein component of this 14-nm filament obviously differ from those of actin filament, 10-nm intermediate filament and microtubule, the 14-nm filament appears to be a newly found intracellular filament. Concerning the FFP-38 polymerization, some polymorphism appeared: we found ring structures having the diameters of 0.3--3.7 micrometers and latticed sheet structure, besides typical straight filaments.

Animals↗
PubMed1980

Recognition of heterologous cells by macrophages. I. Species recognition by mouse and guinea pig macrophages in the phagocytosis of heterologous thymocytes.

The ability of macrophages to recognize homologous and various heterologous cells was studied in mice, rats, and guinea pigs, in terms of the in vitro phagocytosis of non-opsonized viable thymocytes by macrophages. Mouse, rat, and guinea pig macrophages were found to phagocytize actively thymocytes from certain heterologous animals, including chickens. For instance, mouse macrophages displayed conspicuous phagocytic activities against chicken and duck thymocytes, moderate activities against guinea pig and frog thymocytes and weak activities against rat and mouse thymocytes. On the other hand, guinea pig macrophages revealed a different behaviour: they ingested only chicken thymocytes. These observations strongly suggested that mammalian macrophages possess some ability to discriminate homologous from certain heterologous thymocytes. The results, however, did not necessarily support the idea that the degree of phagocytosis is simply related to the phylogenetic distance between the animal species from which thymocytes and macrophages originated, because of the apparent exception in the mode of phagocytosis by guinea pig macrophages. Evidence demonstrating that antibodies are not involved in this phenomenon will be presented in the accompanying paper.

Animals↗
PubMed1980

Combined use of phenoxybenzamine and dopamine for low cardiac output syndrome in children at withdrawal from cardiopulmonary bypass.

The combined use of phenoxybenzamine and dopamine was applied in infants and children when it was difficult to come off cardiopulmonary bypass for low cardiac output. The rationale of this method is to prevent the alpha-adrenergic action of dopamine by phenoxybenzamine and to encourage the beta-adrenergic and direct specific action of dopamine. Dopamine was used in dosage of 10 to 30 micrograms/kg per min after the additional administration of a half of the initial dosage of phenoxybenzamine; this was infused by drip always in a dosage of 0.5 to 1.0 mg/kg during the first half of cardiopulmonary bypass. It was possible to come off cardiopulmonary bypass with a stable haemodynamic state (mean arterial pressure more than 60 mmHg and total peripheral vascular resistance less than 2000 bynes s cm-5) and a good urinary output.

Cardiac Output, Low↗
PubMed1980

Studies on protein binding of antibiotics. I. Effect of cefazolin on protein binding and pharmacokinetics of cefoperazone.

The effect of cefazolin (CEZ) on the protein binding and the pharmacokinetics of cefoperazone (T-1551) was investigated. For the simultaneous determination of T-1551 and CEZ, high pressure liquid chromatography (HPLC) was used. The extent of protein binding, the number of binding sites and the association constant to human serum albumin were 90.4%, 0.87 and 2.16 X 10(4) in T-1551, and 89.2%, 0.78 and 2.46 X 10(4) in CEZ, respectively. T-1551 and CEZ appeared to bind to the same site on the protein, since each drug competitively inhibited the binding of the other to serum protein. The mode of the binding of T-1551 to serum protein was similar to that of CEZ. When T-1551 and CEZ were co-administered, the serum level of T-1551 was lower than that with the single administration, while, urinary excretion was higher. These results suggested that the concomitantly administered drugs influenced one another's binding to serum protein in vivo and subsequently an increase in the concentration of the unbound drug in the serum made the drug available for glomerular filtration. It seemed that the high protein binding of T-1551 to serum was an important factor affecting its pharmacokinetics.

Animals↗