Search PubMed⌕ Search

Biomedical subjects

Y Shioya

Publications and source records attributed to Y Shioya.

11 recordsLinked to original sources
PubMed1992

In vitro fertilization and development of frozen-thawed bovine oocytes.

Bovine oocytes were vitrified (V-oocytes) or frozen slowly (S-oocytes) at the germinal vesicle (GV) stage or after maturation in vitro (IVM) and their survival assessed morphologically and also by in vitro fertilization (IVF) and culture. The morphological survival of S-oocytes was 30.7% after freezing at the GV stage and 53.3% after IVM. The corresponding survival rates of V-oocytes were significantly lower, viz. 14.6 and 14.0%, respectively. The fertilization rate of S-oocytes frozen after IVM (51.0%) was lower than that of unfrozen controls (75.8%), but higher than after other treatments. Development continued in 16.0% of the fertilized S-oocytes, compared to 39.4% of control IVF zygotes and 1.6% developed into morulae or blastocysts (4.5% in controls). Only 0.8% of frozen-thawed GV stage oocytes and 4.6% of post-IVM V-oocytes cleaved after IVF and none formed morulae or blastocysts. Transfer of four embryos (two morulae and two blastocysts) derived from post-IVM S-oocytes into a recipient heifer resulted in pregnancy and the birth of twin calves.

Animals↗
PubMed1990

Two sensitivity levels of cattle oocytes to puromycin.

Germinal vesicle breakdown (GVBD) in cumulus-enclosed and denuded cattle oocytes was sensitive to puromycin at concentrations at or above 50 micrograms/ml. Media supplemented with 5-25 micrograms/ml of puromycin did not significantly reduce either rate or sequence of GVBD after 8 h of culture (82-96% GVBD). In concentrations of 50, 75, and 100 micrograms/ml, GVBD occurred in 15, 4, and 2% of oocytes, respectively. However, 50 micrograms puromycin/ml did postpone the time sequence of GVBD, since all treated oocytes underwent GVBD after 20 h of culture. Oocytes arrested in the germinal vesicle (GV) stage possessed GV filled with highly condensed bivalents. The puromycin block (100 micrograms/ml) was fully reversible, and the time sequence of GVBD was two times faster than in control medium. Proteins important for GVBD were synthesized during the first 4 h of culture, and 81% of oocytes underwent GVBD when puromycin (100 micrograms/ml) was added after 4 h of preincubation in control medium. The first polar body (I PB) expulsion was more sensitive to inhibition of protein synthesis, as shown by the observation that 2.5 and 5 micrograms puromycin/ml significantly (69 and 61%) reduced the incidence of Metaphase II, and 10 micrograms/ml highly significantly (31%) reduced it. The I PB expulsion in concentrations of 25 and 37 micrograms puromycin/ml was less than 5%. The subsequent culture in puromycin (8 h) and 6-dimethylaminopurine (8 h) proved that nuclear membrane breakdown is less sensitive to inhibition of protein phosphorylation than the process of chromatin condensation.

Adenine↗
PubMed1989

Incidence of chromosomal anomalies in early bovine embryos derived from in vitro fertilization.

The incidence of chromosomal anomalies in early bovine embryos derived from follicular oocytes fertilized in vitro using sperm separated by Percoll density gradient centrifugation was investigated. Overall, chromosomal anomalies were observed in 13.7% (138/1005) of embryos. There were 14 haploids (1.4%), 2 hypodiploids (0.2%), 6 hyperdiploids (0.6%), 101 triploids (10.0%), 12 tetraploids (1.2%), 2 diploid/triploid mosaics (0.2%), and 1 diploid/tetraploid mosaic (0.1%). The frequency of triploidy was caused mainly by polyspermy. There was a significant difference in the frequency of embryos with abnormal chromosomes between the two bulls used (P less than 0.005), but Percoll centrifugation did not affect the observed incidence of anomalies. The frequency of chromosomal anomalies in embryos at each stage increased with delay or arrest of development. These results suggest that the incidence of chromosomal anomalies depended on the conditions of in vitro fertilization and the arrest of development.

Aneuploidy↗
PubMed1988

In-vitro fertilization of pig oocytes by frozen boar spermatozoa.

In Exp. 1 pig oocytes matured in vitro were used to evaluate the fertilizability in vitro of frozen epididymal (4 boars) and ejaculated (3 boars) spermatozoa that were preincubated in modified TCM-199 for 4 h at 37 degrees C. The percentages of penetrated oocytes with the frozen epididymal spermatozoa were 0-40%. In contrast, none of the oocytes were penetrated with the frozen ejaculated spermatozoa. In Exp. 2, oocytes matured in vivo were inseminated in vitro with the frozen epididymal spermatozoa that were known to penetrate oocytes matured in vitro. The penetration rate was 79% and the percentage of polyspermic oocytes was 57%. Culture for 30 h of oocytes matured in vivo and fertilized in vitro resulted in 51% (34/67) developing to the 2-cell stage. These embryos were transferred to 2 recipient gilts. One gilt became pregnant and a litter of 3 (1 live and 2 dead) was born. These results indicate that frozen epididymal spermatozoa can be used for in-vitro fertilization in the pig.

Animals↗
PubMed1982

[Interactions between buprenorphine, narcotic analgesic, and centrally acting drugs in prolongation of halothane-induced sleeping and analgesia (author's transl)].

Interactions between buprenorphine, narcotic analgesic, and centrally acting drugs were studied in prolongation of halothane-induced sleeping and analgesia using the D'Amour-Smith method in mice, and the effect of buprenorphine on monoamine metabolism was studied in rat brain. Diazepam and chlorpromazine prolonged the halothane-induced sleeping time dose-dependently. Buprenorphine (0.01, 0.1, and 1 mg/kg s.c.) inhibited the effect of diazepam, but not that of chlorpromazine. Pentazocine and naloxone also inhibited the effect of diazepam, but morphine did not. It is suggested that the inhibitory effect of buprenorphine on prolongation of halothane-induced sleeping time by diazepam is due to its opiate antagonistic property. Since narcotic antagonists inhibited the effect of diazepam, the endogenous opiate system seems to be involved in this effect. Diazepam or droperidol had no effect on the analgesia of buprenorphine, morphine, and pentazocine. Buprenorphine analgesia was inhibited by reserpine and p-chlorophenylalanine, potentiated by 5-hydroxytryptophan, and not affected by alpha-methyl-p-tyrosine or 3,4-dihydroxyphenylalanine. These results suggest that the serotonergic system plays a modulating role in buprenorphine analgesia. Imipramine and nialamide inhibited buprenorphine analgesia in the test at low stimulus intensity, but potentiated at high stimulus intensity. Buprenorphine (0.1, 1 and 10 mg/kg s.c.) increased the dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, in various brain areas and the serotonin metabolite, 5-hydroxyindoleacetic acid, in midbrain.

Analgesia↗
PubMed1969

[Colotomy].

Explore the source record for details and available documents.

Colectomy↗