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Biomedical subjects

C Sato

Publications and source records attributed to C Sato.

At least 343 records · Page 19Linked to original sources
PubMed1983

Growth of a cultured leukemia subline was promoted by conditioned medium of thymic reticuloepithelial-like cells (B6TE).

A murine leukemia subline (L17R) was selectively developed in the presence of conditioned medium of a thymic reticuloepithelial-like cell line (B6TE). Cytotoxicity tests and immunofluorescence microscopy showed that L17R cells were negative in the expression of Thy 1.1, Lyt 1.2 and terminal deoxynucleotidyl transferase (TdT), however, 35% positive in Lyt 2.1 phenotype, and 95% positive in the expression of peanut agglutinin (PNA) receptor. B6TE conditioned medium had no activity of interleukin 1 (IL 1), interleukin 2 (IL 2), interleukin 3 (IL 3) and granulocyte/macrophage colony-stimulating factor (GM-CSF). When L17R leukemic cells were plated at a low cell density, their growth was accelerated 40 times by the addition of concentrated B6TE culture supernatant. This growth activity, tentatively designated leukemia-growth-promoting factor (LGPF), was heat sensitive, and its mol. wt was estimated to be approx. 25,000 from the elution pattern of Sephadex G-100 chromatography.

Animals↗
PubMed1983

Microtubule-organizing centers abnormal in number, structure, and nucleating activity in x-irradiated mammalian cells.

Microtubule-organizing centers (MTOCs) in x-irradiated cells were visualized by immunofluorescence using antibody against tubulin. From two to ten reassembly sites of microtubules appeared after microtubule depolymerization at low temperature in an irradiated mitotic cell, in contrast to nonirradiated mitotic cells, which predominantly show 2 MTOCs. A time-course examination of MTOCs in synchronously cultured cells revealed that the multiple MTOCs appeared not immediately after irradiation but at the time of mitosis. Those multiple MTOCs formed at mitosis were inherited by the daughter cells in the next generation. The structure and capacity of the centrosomes to nucleate microtubules in vitro were then examined by electron microscopy of whole-mount preparations as well as by dark-field microscopy. About 70-80% of the centrosomes derived from nonirradiated cells were composed of a pair of centrioles and pericentriolar material, which initiated greater than 100 microtubules. The fraction of fully active complete centrosomes decreased with time of incubation after irradiation. These were replaced by disintegrated centrosomal components such as dissociated centrioles and pericentriolar cloud, a nucleating site with a single centriole, or only an amorphous structure of pericentriolar cloud. Assembly of less than 20 microtubules onto the amorphous cloud without centrioles was seen in 54% of the initiating sites in mitotic cells 2 d after irradiation. These results suggest that x-irradiation causes disintegration of centrosomes at mitosis when the structural and functional reorganization of centrosomes is believed to occur.

Animals↗
PubMed1983

Monoclonal antibody against microtubule associated protein-1 produces immunofluorescent spots in the nucleus and centrosome of cultured mammalian cells.

A monoclonal antibody was raised against the highest molecular weight protein associated with microtubules (MAP-1). Its specific binding to MAP-1 was determined by immunoblotting of the gel electrophoretogram of microtubule proteins prepared from porcine brain. The antibody reacted only with MAP-1, not with MAP-2, tau or tubulin. Indirect immunofluorescent staining by this antibody showed bright intranuclear spots, the centrosome and the faint meshwork of the cytoplasm in several types of cultured mammalian cells; HeLa, PtK2, human skin fibroblasts, mouse melanoma cells, Chinese hamster ovary cells. The nuclear spots in the interphase cells, were replaced by diffuse enhanced fluorescence throughout the cell except for chromosomes during mitosis. They reappeared in late telophase, first in the cytoplasm, late in the nucleus. The punctate pattern of nuclear immunofluorescence was not affected by microtubule-depolymerizing agents. The result that it persisted on residual cell structures after extraction with a high salt concentration buffer containing Triton X-100 followed by digestion with DNase I and RNase A suggests that the antigen is associated with the nuclear skeleton.

Animals↗
PubMed1983

Immunological study of IgA deficiency during anticonvulsant therapy in epileptic patients.

Of 10 epileptic children with IgA deficiency, one showed normal IgA synthesis and secretion on in vitro pokeweed mitogen (PWM) stimulated lymphocyte culture in contrast to IgA deficiency in vivo, two showed IgA synthesis in cytoplasm without any release of IgA into the supernatant and seven failed to synthesize IgA. Co-cultures with allogeneic T or B cells in various combinations with PWM showed intrinsic IgA-B cell defect without T cell defect in two of the second group affected at IgA secretion and in five of the third group, and intrinsic IgA-B defect with dysfunction of T cells in two of the third group. Thus, the IgA deficiency in these epileptic patients was demonstrated to be heterogenous.

Adolescent↗
PubMed1982

Epifluorescent microscopic evidence for maternal inheritance of chloroplast DNA.

Maternal inheritance of chloroplast genes occurs in the isogamous green alga Chlamydomonas reinhardii. It has been shown using biochemical techniques that the chloroplast DNA of male origin is preferentially lost by 6 h after mating. DNAs in the chloroplast are organized by proteins into about 10 chloroplast nucleoids. Therefore, if chloroplast DNA in zygotes is preferentially destroyed, the disappearance of chloroplast nucleoids from male gametes should be observable during zygote formation by high resolution epifluorescent microscopy. Here we present the first fluorescent microscopic evidence that in C. reinhardii, about eight chloroplast nucleoids from the male parent disappear during the first 40-50 min after mating, while those from the female parent persist and finally fuse together to form one large chloroplast nucleoid.

Cell Fusion↗
PubMed1982

In vitro nucleation of microtubules from microtubule-organizing center prepared from cellular slime mold.

Nucleus associated bodies (NABs) were isolated from Dictyostelium discoideum or Dictyostelium mucoroides and their ability to nucleate microtubules in vitro was examined. NABs were localized at the tapered ends of the nuclei and released from lysed cells in complex with the nuclei. Microtubules radiating from the NAB could also be isolated with the complex under microtubule stabilizing conditions. The ultrastructure of the isolated NAB showed it to be composed of a core structure surrounded by an amorphous matrix. The ability of isolated NABs to nucleate microtubules in vitro was demonstrated by incubation with exogenous brain microtubule protein. Microtubule assembly was easily visualized by dark-field or immunofluorescence microscopy. Polymerization of microtubules seemed to be initiated not from the core structure but from the surrounding matrix. The number of microtubules polymerized from the NAB was directly counted in whole-mount preparations by electron microscopy, which provided a quantitative assay for the NAB activity. The nucleating activity of NAB was quite unstable and its half-life was calculated as about 5 hours. The activity was sensitive to protease digestion and was also temperature sensitive but could be stabilized by addition of glycerol or storage at - 80 degrees C or in liquid nitrogen. These characteristics are analogous to those of the centrosomes in cultured mammalian cells and a possible explanation of their similarity is discussed.

Cell Fractionation↗
PubMed1982

Specific association of bromocresol purple anions with a magnesium complex of a phosphorylated intermediate during steady-state hydrolysis of ATP by the Mg2+ + Ca2+-dependent ATPase of sarcoplasmic reticulum.

The mechanism of dimeric binding of bromocresol purple (BCP) anions to Mg2+ + Ca2+-ATPase of the sarcoplasmic reticulum (SR) and the resulting partial inhibition of the ATPase activity were studied. BCP anions in three states, free monomer, bound monomer, and bound dimer, were spectrophotometrically calculated by solving simultaneous equations, delta A lambda 1-lambda 2 = sigma delta ai (epsilon i lambda 1-epsilon i lambda 2), and concentration changes of these states were analyzed. The addition of ATP caused an increase in the bound dimer and a decrease in the free monomer, but the change of the bound monomer was slight. The decrease in delta A (decrease phase) on the addition of ATP on dual-wavelength spectrophotometry at 585-610 nm was related to an increase in the amount of dimer bound to the SR membranes. The magnitude of the decrease phase increased with an increase in Mg2+ concentration and decreased with an increase in the concentration of Ca2+. BCP anions at the probe concentration partially inhibited the ATPase activity, and brought about a decrease in the ADP-sensitive E-P (E1P) and an increase in the ADP-insensitive E-P (E2P), though BCP anions did not affect the amount of total E-P. On elimination of Mg2+ at the steady-state E-P level both E2P and E2P . (BCP)2 were decomposed, suggesting that the enzyme form binding the BCP dimer was Mg . E-P. An increase in Mg2+ concentration increased E2P but an increase in Ca2+ concentration decreased E2P. Decomposition of E2P to P1 was inhibited by BCP anions. The following simple scheme was suggested to explain the partial inhibition of the ATPase activity, (Formula: see text). Application of BCP anions was discussed for use as a probe for Mg . E-P in the steady-state ATP hydrolysis.

Adenosine Triphosphate↗
PubMed1981

Rapid isolation and lipid characterization of plasma membranes from normal and malignant lymphoid cells of mouse.

A rapid isolation method was developed for plasma membranes from mouse lymphoid cells such as lymph node lymphocytes, thymocytes, radiation-induced thymoma cells and L1210 cells. Lysates of these lymphoid cells were prepared by Dounce homogenization under hypotonic conditions and directly layered on sucrose step density gradients containing 2 mM CaCl2 and 5 mM MgCl2, and centrifuged at 52 000 X g for 1 h. Plasma membrane fractions appeared at the interface between 20 and 42% sucrose in the gradients. The procedure permitted purified membranes from cells to be obtained within 3 h, and the preparations appeared to be uniform by electron microscopy. Specific activities of (Na+ + K+)-ATPase, Mg2+-ATPase and 5'-nucleotidase of the isolated plasma membranes were enriched 23- to 61-fold, 12- to 15-fold and 18- to 34-fold, respectively, in comparison with those of the corresponding cell homogenates. Cholesterol content of the malignant cell membranes was lower than that of the normal membranes and the molar ratio of cholesterol to phospholipid of the malignant cell membranes was also lower than that of the normal membranes. A decreased plasmalogen content was observed in the malignant plasma membranes, together with a higher percentage of phosphatidylethanolamine and a lower percentage of phosphatidylserine. In the normal cell membranes, thymocytes contained a higher percentage of phosphatidylcholine and a lower percentage of sphingomyelin than those of the lymph node lymphocytes. At all temperature ranges (5 to 40 degrees C) the plasma membranes of the malignant cells had lower microviscosity than those of the normal cells.

Animals↗
PubMed1981

Thyroid hormones effects on RNA synthesis in brain and liver of neonatal hypothyroid rats.

The effect of replacement therapy with thyroid hormones upon RNA transcription was studied in isolated nuclei of cerebrum and liver from hypothyroid rats. The chronic administration of T4 to hypothyroid rats, from the 5th day of life, during ten days, corrected the RNA synthesis in isolated nuclei from cerebrum and liver. The injection of a single dose of T3 to neonatally thyroidectomized rats, ten days after birth, enhanced the endogeneous activity of RNA polymerase I and II of cerebrum and liver. In cerebrum the transcription of ribosomal RNA increased 40 minutes after T3 injection, this activity being constant during the whole period studied. On the other hand, the synthesis of heterogeneous RNA showed an increase only 5 hrs. after the beginning of the treatment. In liver, the lag period is higher for both enzymes, being the maximal response achieved 5 hs. after the hormonal administration.

Animals↗
PubMed1981

Effects of hyperthermia on cell surface charge and cell survival in mastocytoma cells.

Changes in the structure of the surface of mastocytoma cells were induced by hyperthermia and were investigated by means of cell electrophoresis. A decrease in the cell electrophoretic mobility was detected as early as 15 min after treatment at 42 degrees and progressed more rapidly under hypoxic conditions than under oxic conditions. Subsequent recovery of electrophoretic mobility at 37 degrees was dependent on the length of heat treatment and oxygenation. The surviving fraction of cells detected by their colony-forming ability and the fraction of electrophoretically recovered cells 24 hr after exposure to hyperthermia showed a good statistical correlation. It was suggested that the mechanism of electrophoretic mobility reduction by heating was the vertical translocation of hyaluronidase-sensitive charge from the peripheral layer into a deeper layer by combined use of specific enzymes and stepwise different ionic strengths. These results suggest the importance of irreparable changes of membrane conformation in the loss of colony-forming ability of heated tumor cells.

Animals↗
PubMed1981

Glucocorticoid-induced membrane alteration of thymocytes and thymic phagocytosis.

Electrophoretic mobility (EPM) of thymocytes progressively decreased after an i.p. injection of 10 mg hydrocortisone, and reached its lowest value 3 hr later. The degree of the decrease in the EPM of thymocytes was dependent on the dose of hydrocortisone. Thymic phagocytic cells began to ingest thymocytes in vivo 2 hr after hydrocortisone injection, and thymic phagocytosis continued up to 8 hr. Glucocorticoid-induced phagocytosis was also detected in vitro, i.e., primarily cultured thymic phagocytic cells ingested membrane-altered viable thymocytes from 10-mg hydrocortisone-treated mice 4 to 10 times more than control thymocytes. It was considered from these results that the decrease in the negative surface charge of thymocytes is closely associated with the phagocytosis of thymocytes by thymic phagocytic cells.

Animals↗
PubMed1981

Increased hepatotoxicity of acetaminophen after chronic ethanol consumption in the rat.

This study was undertaken to evaluate the effects of chronic ethanol consumption on the hepatotoxicity of acetaminophen. Male Sprague-Dawley rats were pair fed a nutritionally adequate liquid diet containing either ethanol or isocaloric carbohydrate for 4-6 wk. Acetaminophen (0.5 g/kg body wt) was given intraperitoneally 12 h after ethanol withdrawal. By 36 h, frank hepatic centrilobular necrosis and a decrease in hepatic aminopyrine N-demethylase activity were observed in the ethanol-fed rats, whereas in controls the changes were minimal. Serum glutamyl oxaloacetic transaminase and glutamate dehydrogenase activities were significantly increased in ethanol-fed rats. Hepatic damage in ethanol fed rats was apparent already at 6 h, as evidenced by elevated serum enzyme activities and ultrastructural changes, particularly of the mitochondria. The depletion of hepatic glutathione content and the covalent binding of acetaminophen metabolite(s) were significantly greater in ethanol-fed rats than in controls. Urinary excretion of mercapturic acid conjugate during the first 12 h was also increased in ethanol-fed rats. In an in vitro study, covalent binding of acetaminophen metabolite(s) to microsomal protein was increased after ethanol feeding for 4-6 wk. Thus, chronic ethanol feeding increases the hepatotoxicity of acetaminophen; enhanced production of reactive metabolite(s) may be responsible.

Acetaminophen↗