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Biomedical subjects

Y Toyoda

Publications and source records attributed to Y Toyoda.

At least 253 records · Page 14Linked to original sources
PubMed1989

In vitro capacitation of boar ejaculated spermatozoa: effect of conditioned media prepared from preincubated sperm suspension.

The fertilizing ability of boar ejaculated spermatozoa was examined in vitro after preincubation at a concentration of 2.5 x 10(8)/ml for 4 hr in several conditioned media (CM). For preparation of CM, boar spermatozoa were incubated in a modified Krebs-Ringer bicarbonate solution (TYH) at concentrations of 20 to 40 x 10(8)/ml for several hours up to 4 hr; then their supernatant fluids were collected by centrifugation. When boar ejaculated spermatozoa were preincubated in TYH alone, 14.1% of oocytes were penetrated by them as we reported previously. On the other hand, preincubating them with CM, their fertilizing ability was elevated according as the incubation time of CM preparation was lengthened. The fertilization rate reached 75.0%, using 4 hr-incubated CM for the preincubation medium. The effect of CM was not deteriorated by heat treatments (56 degrees C, 30 min, or 100 degrees C, 5 min). The components of CM were separated at a molecular weight of 25,000 by ultrafiltration, and high fertilization rate (69.8%) was obtained when low molecular weight fraction was used for the preincubation medium. Sperm extracts prepared from directly frozen-thawed sperm suspension and 0.1-10 mM of taurine or hypotaurine had no effect on the fertilizing ability of boar spermatozoa. These results suggest that substances stimulating boar sperm capacitation were accumulated from viable spermatozoa into the medium during incubation and that the effective substances were heat-stable and of low molecular weight and were not taurine and hypotaurine.

Animals↗
PubMed1989

Effect of route of administration in the micronucleus test with potassium bromate.

The effect of intraperitoneal injection (i.p.) versus oral gavage administration (p.o.) of potassium bromate was examined using the micronucleus test in 2 strains of male mice (MS/Ae and CD-1). First, a small acute toxicity test and a pilot micronucleus experiment were performed to determine the appropriate dose range and sampling time for the full-scale micronucleus test. The full-scale test was carried out using doses of 18.8, 37.5, 75, and 150 mg/kg in the i.p. test and of 37.5, 75, 150, and 300 mg/kg in the p.o. test. The sampling time was 24 h for both mouse strains. Potassium bromate induced micronucleated polychromatic erythrocytes (MNPCEs) dose-dependently by both routes of administration in both mouse strains. No distinct difference in route of administration was observed in the test with MS/Ae mice. In CD-1 mice more MNPCEs were induced by the i.p. route than by the p.o. route.

Administration, Oral↗
PubMed1989

Micronucleus test with potassium chromate(VI) administered intraperitoneally and orally to mice.

The effect of route of administration, intraperitoneal (i.p.) or oral gavage (p.o.), in the mouse micronucleus test was studied with K2CrO4 in 2 mouse strains (MS/Ae and CD-1). A simplified acute toxicity test to estimate the toxic dose levels of K2CrO4 showed that the LD50S were 50 mg/kg i.p. and 300 mg/kg p.o. for MS/Ae and 32 mg/kg i.p. and 180 mg/kg p.o. for CD-1. Based on results of a pilot micronucleus test to determine appropriate dose levels and the optimal sampling time, it was decided to sample bone marrow cells of both strains of mice 24 h after i.p. doses of 10-80 mg/kg and p.o. doses ranging from 20 to 320 mg/kg. K2CrO4 administered i.p. induced micronucleated polychromatic erythrocytes (MNPCEs) dose-dependently in both strains. In contrast, when administered p.o. the chemical failed to induce MNPCEs. These results suggest that this difference between i.p. and p.o. routes is related to a difference of absorption or metabolic fate of chromate in vivo.

Administration, Oral↗
PubMed1989

An enzyme immunoassay for human lymphotoxin.

A highly sensitive and specific enzyme immunoassay (EIA) for human lymphotoxin (hLT) has been developed. The assay is based upon a sandwich system employing two kinds of anti-hLT antibodies with neutralizing activity. One of them was mouse monoclonal antibody raised against Escherichia coli-derived recombinant hLT with a deletion of 20 amino-terminal amino acids and used as labelled antibody. The other was rabbit antibody raised against the carboxyl-terminal portion of hLT and used as solid-phase antibody. The EIA employing such a combination was able to detect less than 50 pg/ml of hLT, showing that this method was approximately 5-10 times higher sensitivity than the conventional bioassay employing L929 cell-lysis. The mean recovery of hLT added to serum specimens was 101% and the coefficients of variation were 3.3-7.8% (intra-assay) and 2.9-17.2% (interassay). There was a good correlation between the present EIA and the bioassay (r = 0.93).

Animals↗
PubMed1989

Bispecific antibody-producing hybrid hybridoma and its use in one-step immunoassays for human lymphotoxin.

A hybrid hybridoma cell line secreting a bispecific monoclonal antibody (MAb) was constructed by fusing horseradish peroxidase (HRPO)-immunized mouse splenocytes with previously established mouse hybridomas secreting anti-human lymphotoxin (hLT). This cell line was grown in ascitic fluid in mice to obtain large quantities of hybrid MAbs and a bispecific antibody, reacting with both HRPO and hLT, was separated from the monospecific antibody or other inactive immunoglobulin populations by hydroxylapatite chromatography. Sodium dodecylsulfate-polyacrylamide gel electrophoresis demonstrated that the bispecific antibody molecule contained two different types of heavy and light chains of both anti-HRPO and anti-hLT origin. The bispecific antibody was used to establish one-step enzyme immunoassays (EIAs) employing competitive and sandwich systems. The simple sandwich EIA was able to detect 1-100 U/ml of hLT and there was good correlation (r = 0.96) between hLT concentrations measured by the one-step EIA and a bioassay using L929 cell-lysis.

Antibodies, Monoclonal↗
PubMed1989

[Hemopoietic factor producing hepatocellular carcinoma in a child].

A 12-year-old boy with hepatocellular carcinoma presented with marked neutrophilia up to 69,200/microliters and elevation of serum colony stimulating activity (CSA) and burst promoting activity (BPA). After resection of the tumor, neutrophil count returned to the normal value and hemopoietic activities in serum decreased. However, on relapse, both elevated to the preoperative levels. Hemopoietic activities in the medium conditioned with tumor tissue were investigated using normal human bone marrow as the target cells, and both CSA and BPA were demonstrated. From these findings, it could be considered that the tumor tissue produced a substance that stimulated both myelopoiesis and erythropoiesis.

Carcinoma, Hepatocellular↗
PubMed1988

Effects of porcine follicular fluid on male pronucleus formation in porcine oocytes matured in vitro.

Porcine follicular oocytes, collected from antral follicles (2-5 mm in diameter) of gilt ovaries, were matured in vitro with or without porcine follicular fluid (pFF), gonadotrophins (GTH) or fetal calf serum (FCS) for 48 hours at 37 degrees C under 5% CO2 in air, and their ability of male pronucleus (mPN) formation was examined after in vitro fertilization. Formation of mPN was observed in 38.6% of penetrated oocytes matured in modified Krebs-Ringer bicarbonate solution (TYH) 18 hours after insemination. The addition of GTH into the maturation medium did not improve the proportion of mPN-formed oocytes (20-30%). In contrast, the mPN formation rate elevated significantly (59.5%) when the oocytes were cultured with pFF, and the addition of follicle-stimulating hormone (FSH) enhanced this pFF action (the rate became 81.0%). In the presence of FSH, significant pFF effect was observable at the concentration of 5%, and its efficiency was elevated with the increase of pFF concentration. When the oocytes were matured with FCS, the mPN formation rate was unchanged or decreased rather than improved (0-25%). These results suggest that pFF, but not FCS, have substance(s) stimulating the ability of mPN formation in porcine oocytes.

Animals↗
PubMed1988

Leucocytosis and severe pain due to ureteral calculi.

We reviewed the outcome of 300 cases without urinary tract infections to determine the relationship between leucocytosis and severe pain due to ureteral calculi. Leucocytosis above 9,000 cells per cmm was seen in 87.7% of the cases. Many patients (61%) had a leucocyte count between 9,000 and 12,000, but none had that exceeding 22,000. This leucocytosis can be attributed to a transient distributional alteration by means of leucopheresis to circulation sites from a storage pool such as the blood vessels in the spleen, liver, lung, etc. Since leucocytosis often accompanies ureteral calculi, caution should be exercised in distinguishing it from appendicitis.

Adult↗
PubMed1987

Anomeric specificity of glucose effect on cAMP, fructose 1,6-bisphosphatase, and trehalase in yeast.

The addition of beta-D-glucose (final concentration, 50 mM) to a cell suspension of Saccharomyces cerevisiae in stationary phase caused a rapid 4-fold increase in the concentration of cAMP, while a 2-fold increase of cAMP was observed by the addition of alpha-D-glucose. beta -D-Glucose was also more effective than alpha-D-glucose in the inactivation of fructose 1,6-bisphosphatase and the activation of trehalase. These results, taken together with the previous report that alpha-D-glucose is transported more rapidly than beta-D-glucose in Saccharomyces cerevisiae, do not support the view currently proposed by some investigators that cotransport of D-glucose with protons causes the depolarization of the cell membrane, resulting in the activation of adenylate cyclase. The present data, however, provides supporting evidence for the view that cAMP-dependent protein kinase is implicated in the inactivation of fructose 1,6-bisphosphatase and the activation of trehalase.

Cyclic AMP↗