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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 1,261 records · Page 70Linked to original sources
PubMed1988

Activity and stability of recombinant human superoxide dismutase in buffer solutions and hypothermic perfusates.

The stability of recombinant human superoxide dismutase (r-hSOD) in buffer solutions was studied in solutions at various pH and temperatures. Additionally, we studied the effects of incubation with proteases, serum and two types of hypothermic perfusates. R-hSOD was stable in the pH range of 6-11 and at temperatures up to 80 degrees C for 30 min. R-hSOD activity was not affected by incubation with trypsin, aminopeptidase M or serum for 2 h. R-hSOD activity determined at various temperatures (4-37 degrees C) did not vary remarkably. R-hSOD in hypothermic perfusates was stable at 4-37 degrees C for 24 h.

Buffers↗
PubMed1988

Experimental study of vagotomy for prevention of stress ulcer after hepatectomy of cirrhotic livers. Its influence on hepatic regeneration.

We experimentally studied the influence of vagotomy on hepatic regeneration in rats after hepatectomy of cirrhotic livers. In animals that underwent hepatectomy plus vagotomy the reduction in gastric pH was suppressed, but gastric mucosal blood flow was less than that in control animals that received hepatectomy alone. The suppression of 3H-thymidine uptake percentage and thymidine kinase activity after hepatectomy was more marked in animals treated with hepatectomy plus vagotomy than in controls treated with hepatectomy alone. Hepatic DNA level tended to be lower in animals treated with hepatectomy plus vagotomy than in controls. In animals treated with hepatectomy plus vagotomy, the peak level of the mitotic index was lower and the hepatic regeneration rate was evidently suppressed. These results suggest that it is not appropriate to apply vagotomy, during hepatectomy of cirrhotic livers, for the prevention of postoperative stress ulcer because it causes a marked reduction in gastric mucosal blood flow and suppresses hepatic regeneration.

Animals↗
PubMed1988

[A study on the mechanism of activation of peritoneal exudate macrophages from MRL/MpJ-lpr/lpr mice].

MRL/MpJ-lpr/lpr (lpr/lpr) mice are congenic mice of the lpr gene which encodes the massive proliferation of unusual T cells characteristic of Thy 1+, Lyl1+, L3T4-, Lyt2- and B220+ on cell surface. These mice spontaneously develop a progressive autoimmune disease such as glomerulonephritis, arthritis and granulomatous arteritis. Until now, it has been reported that peritoneal exudate macrophages (PEM) from lpr/lpr mice are activated in comparison with those from MRL/MpJ-+/+ (+/+) mice. In this paper, five PEM functions [anti-tumor activity, IL-1 activity, TNF activity, superoxide (O2-) production and proliferative capacity] were analysed to elucidate the mechanism of activation of PEM from lpr/lpr mice. The results indicated that lpr/lpr PEM had a significant increase in cytostasis and O2- production and a significant decrease in proliferative capacity, suggesting that PEM from lpr/lpr mice were activated to the level of primed macrophage. To examine the effect of contaminated nonadherent peritoneal exudate cells (NAPEC) from lpr/lpr mice on PEM activity, cell mixing experiments were performed. B220- cells out of NAPEC from lpr/lpr mice significantly enhanced O2- production by +/+ PEM. Furthermore, Lyt2+ splenic T cells also enhanced O2- production by +/+ PEM. The culture supernatants of spleen cells from lpr/lpr mice contained so called "MAF" activity, because they enhanced O2- production by +/+ PEM significantly. Moreover, the culture supernatants of Con A-stimulated spleen cells from lpr/lpr mice showed higher IFN-gamma activity than those from +/+ mice. Such higher IFN-gamma activity was present in the supernatants of Con A-stimulated B220- splenic T cells. These results suggested that Lyt2+ NAPEC from lpr/lpr mice produced MAF-like-lymphokine, possibly IFN-gamma, which activated PEM in vivo. While the culture supernatants of non-stimulated PEM from MRL mice had no IL-1 and TNF activity, those of recombinant IFN-gamma-stimulated PEM from lpr/lpr mice had higher IL-1 and TNE activity than those from +/+ mice. These data indicated that lpr/lpr PEM were more sensitive to IFN-gamma than +/+ PEM.

Animals↗
PubMed1988

[Recent advances in retinoids studies].

Retinoids are defined as the compounds which elicit the specific biological responses through binding or activating the specific receptor(s). Retinoids modulate the cellular differentiation and proliferation in many types of cells. A series of retinoidal benzoic acids, named retinobenzoic acids, have potent activities on human promyelocytic leukemia cells, HL-60, and other assay systems. Among them, Am80, AM580 and Ch55 are more active than retinoic acid in most cases. As these compounds possess quite different structures or physicochemical properties from retinoic acid or conventional retinoids, they are expected to be applied clinically for the treatments of the diseases in oncology and dermatology. Recently, progresses on the mechanistic studies on retinoidal actions have been reported. One of them is isolation and cloning of human retinoic acid-receptors and the mechanism of retinoidal action was concluded that the retinoid-receptor complex interact directly with DNA to regulate the expression of the gene, like steroid hormone. The other is the establishment of the presence of the retinoid-specific-binding protein (RSBP) by the use of our retinobenzoic acids as the probe.

Animals↗
PubMed1988

Properties of target molecule of murine lymphokine-activated killer (LAK) cells and the clones.

Properties of mouse lymphokine activated-killer (LAK) cells were examined by using polyclonal and monoclonal LAK cells. To identify cell types of LAK cells, LAK cells were induced from various mouse lymphoid tissues and examined for the surface phenotypes by means of negative selection and FACS analysis. Irrespective of the cell sources, LAK cells expressed Thy 1 and lymphocyte function-associated antigen 1 (LFA-1) as common markers but the expressions of asialoGM1 and Lyt antigens were different from their cell sources. The induction of LAK cells from spleen cells was more frequent in asialoGM1+, Lyt 2- (natural killer (NK) cell type) cells than in asialoGM1-, Lyt 2+ (T cell type). To further assess the properties of LAK cells, we established LAK cell clones from LAK cell lines induced from C57BL/6 mouse spleen cells. Although these clones expressed the similar phenotypes to the parent LAK cells, Lyt 2 was expressed in a limited portion of the clones. All clones were found to express T3 and T cell receptor (TcR)-alpha beta, and rearrangement patterns of TcR-beta were the same among the clones derived from the same parent cell line but different in clones derived from different cell lines as determined by using C beta 1 and J beta 2 probes. The molecules responsible for LAK-target cell binding were examined by using killer blocking antibody (KBA) (anti-LFA-1) monoclonal antibody (mAb) and anti-idiotypic polyclonal antibody (Id) to KBA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[Monoclonal antibodies against tumor associated antigens].

By the use of xeno-immunization, syngeneic immunization, or human lymphocytes, we prepared monoclonal antibodies against human epithelial tumors, especially against bladder tumors. Here, we describe results of antigen analyses and application to the tumor diagnosis.

Animals↗
PubMed1988

General pharmacological studies on N-(2,6-dimethylphenyl)-8-pyrrolizidineacetamide hydrochloride hemihydrate. 1st communication: effect on the central nervous system.

The pharmacological actions of N-(2,6-dimethylphenyl)-8-pyrrolizidineacetamide hydrochloride hemihydrate (SUN 1165), a new antiarrhythmic agent, on the central nervous system were studied in various experimental animals as compared with those of disopyramide, mexiletine and lidocaine, and the following results were obtained. 1. Acute toxicity of SUN 1165 in mice was similar to that of mexiletine, and twice as potent as compared with that of disopyramide and lidocaine. Main acute toxic symptoms of SUN 1165 were muscle relaxation, ataxia, clonic convulsions, tremor and a decrease in spontaneous activity in mice, rats and rabbits. In addition to these symptoms, vomiting in dogs was observed. These toxic symptoms were similar to those of lidocaine. In the case of disopyramide, ataxia, tremor and a decrease in spontaneous activity were observed in mice and rats. On the other hand, mexiletine caused central nervous excitatory symptoms, that is, tremor, Straub tail, clonic convulsions, jumping, running and opisthotonus in mice and rats, and vomiting in dogs. 2. SUN 1165 even at large doses (50-100 mg/kg p.o.) exerted no significant effects on the following changes: hexobarbital-induced induced hypnosis, oxotremorine-induced tremor, apomorphine-induced hypothermia, reserpine-induced ptosis and hypothermia, 5-hydroxytryptophan syndrome and fighting behavior in mice, and conditioned avoidance response in rats. 3. An ineffective dose of SUN 1165 (12.5 mg/kg p.o.) on spontaneous locomotor activity was lower than of disopyramide and lidocaine, however, higher than that of mexiletine. 4. SUN 1165 at large doses showed antagonistic action on toxic extensor seizures induced by maximal electroshock, picrotoxin, or strychnine in mice, but anticonvulsive effects of SUN 1165 were less potent than those of mexiletine and lidocaine. SUN 1165 had no effect on clonic convulsions induced by pentetrazol and pictrotoxin in mice, while both mexiletine and lidocaine prolonged the duration of clonic convulsions. 5. The muscle relaxant effect of SUN 1165 (50%-toxic dose, TD50 = 30 mg/kg p.o.) was more marked than that of lidocaine (TD50 = 92 mg/kg p.o.) on traction test in mice. However, effect of SUN 1165 (TD50 = 62 mg/kg p.o.) on motor incoordination was similar to that of disopyramide, mexiletine and lidocaine on the rotarod test in mice. 6. The analgesic effect of SUN 1165 was as weak as that of disopyramide, mexiletine and lidocaine on chemically and mechanically-induced pain response in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

Increased thymidylate synthase (EC 2.1.1.45) activity in normal and neoplastic proliferation.

Thymidylate (dTMP) synthase (EC 2.1.1.45) activity was measured in 100,000 x g supernatant fluid with a sensitive, rapid radio assay. The activity in normal rat liver was low (0.098-0.204 nmol/hr/mg protein). dTMP synthase specific activities in rat thymus, spleen, bone marrow, testis, lung, heart, brain, kidney, and small intestine were 6297, 1842, 1500, 788, 215, 76, 61, 39 and 24%, respectively, of that of the liver. The activity in 5-day-old rat liver was 16-fold higher than in adult. dTMP synthase activity increased in rat hepatomas to 7- to 125-fold of that of normal rat liver. There was a significant correlation between the increase in synthase activity and the proliferation rates of the hepatomas. In 8 human colon carcinomas, dTMP synthase activity increased to 2.9- to 8-fold of that of normal human colon mucosa. In leukemic leukocytes from 3 leukemia patients, activity was 8- to 10-fold higher than in normal leukocytes.

Aging↗
PubMed1988

Characterization of resident peritoneal cells in MRL mice.

Detection of cell surface markers and cell surface receptors of resident peritoneal cells in MRL/Mp-1pr/1pr (MRL/1) and MRL/Mp-+/+ (MRL/n) mice was made by cytotoxic assay using anti-Thy1.2 and anti-IAk or anti-IE antibodies and rabbit anti-sheep red blood cell IgG coated sheep erythrocytes, respectively. MRL/1 mice showed a remarkable increase in the number of peritoneal cells, the main cells of which were not macrophages but T-cells. The cell surface Fc gamma-receptors on the peritoneal macrophages increased and their immune phagocytosis mediated by Fc gamma-receptors was enhanced. Ia expression of the macrophages showed a high value from in early life, but decreased at the end of life. On the contrary, MRL/n mice showed a low value in early life, which then increased after 15 weeks and continued at a high value until 25 weeks, the end of the experimental period. We described the characteristic increment of T-cells in the peritoneal cavity of MRL/1 mice and discussed the relationship between Ia expression and development of autoimmune symptoms in MRL/1 and MRL/n mice.

Animals↗