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Biomedical subjects

A Iritani

Publications and source records attributed to A Iritani.

At least 55 records · Page 3Linked to original sources
PubMed1988

Development of hamster two-cell embryos in the isolated mouse oviduct in organ culture system.

Hamster early two-cell embryos developed to the expanded blastocyst stage within the isolated mouse ampulla maintained in organ culture system. Mouse ampullae isolated at different times after treating the mice with human chorionic gonadotropin (hCG) (0-72 h) or pregnant mare's serum gonadotropin (PMSG) (30-32 h) were flushed with culture medium, and hamster early two-cell embryos were introduced into these ampullae. Mouse ampullae isolated at 14-32 h after hCG injection were more favorable for the development of the embryos than those isolated at 70-72 h. When mouse ampullae were isolated 30-32 h after hCG or PMSG treatment, 39% of the cultured eggs developed, some of them to the expanded blastocyst stage after additional culture for 65-70 h. These results indicate that unknown oviductal factors stimulate the development of hamster early two-cell embryos, and these factors are under the control of hCG or PMSG. In addition, these factors are common to the mouse and hamster.

Animals↗
PubMed1986

Nucleotide sequence of exon I of the rat c-K-ras gene.

We have isolated a DNA fragment containing exon I of rat cellular proto-oncogene of K-ras and sequenced the exon I. The obtained sequence was compared with that of the corresponding region in viral oncogene of Kirsten strain of murine sarcoma virus (Ki-MSV). The results showed that the exon I sequences of cellular K-ras genes in rat and human cells could encode the same amino acid sequence, while the viral K-ras gene could code for two different amino acids corresponding to the 12th and 37th positions from the N-terminus of K-ras gene product. The amino acid substitutions found between viral and cellular K-ras genes are discussed in relation to the transforming ability of Ki-MSV.

Animals↗
PubMed1985

Early events of in-vitro fertilization of cat eggs by epididymal spermatozoa.

Newly ovulated eggs from mature queens treated with PMSG and hCG were inseminated in modified KRB solution with spermatozoa recovered from the cauda epididymidis of male cats. When 5 eggs were examined 15 min after insemination, no signs of sperm penetration into the vitellus were observed. However, in an egg examined before fixation 20 min after insemination, a spermatozoon whose head had passed through the zona pellucida was observed. Very high proportions (90-100%) of the eggs were penetrated when they were examined 0.5-5 h after insemination. Male and female pronuclei were first observed in eggs examined 4 h after insemination.

Animals↗
PubMed1984

Effect of sperm concentration during preincubation in a defined medium on fertilization in vitro of pig follicular oocytes.

Pig follicular oocytes cultured in a defined medium for 28-29 h were inseminated in vitro by epididymal or ejaculated boar spermatozoa that were preincubated in a modified KRB solution at various sperm concentrations for 4 h at 37 degrees C. Sperm concentration at insemination was 2 X 10(6) cells/ml. When epididymal spermatozoa were preincubated at concentrations of 4-16 X 10(8) cells/ml, 71-75% of oocytes were penetrated. In contrast, preincubation at a low concentration (0.8 X 10(8) cells/ml) resulted in a low penetration rate (11%). Epididymal spermatozoa preincubated at a concentration of 4 X 10(8) cells/ml could also penetrate denuded oocytes. None of the oocytes were penetrated by epididymal spermatozoa that were exposed to seminal plasma before preincubation or by ejaculated spermatozoa. After preincubation, whiplash motility was observed in the epididymal spermatozoa, but not in the ejaculated spermatozoa.

Animals↗
PubMed1984

Fertilization in vitro of cattle follicular oocytes with ejaculated spermatozoa capacitated in a chemically defined medium.

Cattle follicular oocytes were collected from the ovarian follicles and cultured for 28 h in m-KRB solution in a CO2 incubator (5% CO2 in air at 37 degrees C, 95% humidity). After further culture for 15-18 h with spermatozoa, 78.6% of the oocytes had matured to the second metaphase. The highest fertilization rates (36-58%) were obtained when spermatozoa were collected 1 day before insemination, kept for 14-18 h at 20 degrees C in a test tube (10 X 10(8)/ml), preincubated in m-KRB solution (1-1.2 X 10(8)/ml) in a CO2 incubator for 0-12 h, and then inseminated at a concentration of 1.5-2.0 X 10(6)/ml. The optimum period of preincubation in the CO2 incubator was 8 h: 6/15 denuded oocytes (40%) were fertilized with spermatozoa preincubated for 8 h. No polyspermic fertilization was observed in any of the 139 penetrated oocytes. When spermatozoa were preincubated in the uteri of oestrous cows and gilts for 4-4.5 h instead of the m-KRB solution, the fertilization rates were 80 and 86%, respectively. However, in this system, 13 and 24% of the penetrated oocytes were polyspermic. These results indicate that ejaculated bull spermatozoa can be capacitated in a chemically defined isotonic medium, and about half of the oocytes matured in culture are normally fertilized in vitro.

Animals↗
PubMed1984

Biochemical and serological studies on oral ureaplasma.

This study was conducted to study chemically and serologically the characteristics of the Ureaplasmas isolated from the human oral cavity. Two hundred and fifty-one healthy and 12 periodontitis subjects were examined for the incidence of the isolation of Ureaplasmas from their oral cavity. A total of twenty-six strains was isolated from the healthy human saliva. But no strains could be isolated from a variety of clinical specimens obtained from the patients. The serological properties of the isolates were tested by the method of metabolism inhibition test (MI test). Seven out of 26 isolates were serologically identical with either one of the ATCC standard strains. However, the serological types of the other strains could not be demonstrated by the MI test. The biological characteristics of 4 isolates and ATCC strains were tested by the usual method. The isolates did not metabolize glucose and arginine, while all strains hydrolyzed urea. On the other hand, none of the isolates lysed skimmed milk and gelatin. The proteolytic activity of the isolates could be demonstrated by using casein and horse serum proteins as substrates. Zymogram patterns from one of the isolates and Streptococcus salivarius were obtained by polyacrylamide gel electrophoresis of the cells lysed with digitonin or cell protein extracts. On the basis of the gel electrophoresis patterns, it is clear that the urease of the Ureaplasma is different from that of the Streptococcus salivarius.

Animals↗
PubMed1983

Protective effect of sucrose on the survival of mouse and rat embryos stored at 0 degree C.

Mouse and rat embryos were stored at 0 degree C for 24-120 h in PBS containing sucrose. Higher proportions of mouse morulae developed into expanded blastocysts in culture when they were stored in 0.25, 0.5 or 0.75 M-sucrose than in 0, 0.1 or 1.0 M-sucrose. The greatest survival rates were obtained with 0.75 M-sucrose when examined after 48 (72%), 72 (62%) and 96 (41%) h of storage. No rat morulae developed after storage at 0 degree C for 24 h in PBS, but when 0.5 or 0.75 M-sucrose was added to the storage medium, 50-68% of embryos developed into blastocysts in culture, the proportions decreasing until they reached 15-21% after 120 h of storage. Mouse and rat embryos stored at 0 degree C for 3-4 days were transferred to recipients, and 2/2 mice and 1/2 rats delivered full-term young. When mouse embryos stored in 0.75 M-sucrose were frozen to -196 degrees C or when freshly collected frozen-thawed embryos were stored at 0 degree C, embryonic survival was improved when the embryos were incubated for 1-6 h between the two treatments.

Animals↗
PubMed1982

The effect of sperm concentrations during preincubation and at insemination on fertilization of rat eggs in vitro.

Rat epididymal spermatozoa, at a concentration of 40-65 X 10(4) cells/ml, were preincubated for 5-5, 5 hr and then added to eggs from superovulated, immature rats. By 10-12 hr after insemination, 86% of the eggs had undergone fertilization, but many of them (41%) were polyspermic. When sperm were preincubated at almost the same concentration and for the time stated above, but then diluted to 1-3 X 10(4) cells/ml before insemination, the number of fertilized eggs and the incidence of polyspermy were both reduced, being 56% and 5%, respectively. When a sperm concentration of 1-3 X 10(4) cells/ml was used both during preincubation and at insemination, the fertilization rate of 60% or more, with polyspermy not in excess of 10%, a sperm concentration of 30-100 X 10(4) cells/ml during preincubation and then diluted to approximately 1-3 X 10(4) cells/ml at insemination appears to be optimal.

Animals↗
PubMed1982

The importance of the presence of metabolizable sugars in a medium for in vitro fertilization of hamster eggs with postovulatory oviduct contents.

Hamster eggs with postovulatory oviduct contents were added to a simple defined medium, without serum albumin, but supplemented with different combinations of energy sources. They were then inseminated by epididymal spermatozoa. In a medium containing D-glucose but without pyruvate and/or lactate, high proportions of acrosome-reacted spermatozoa (78-94%) and eggs undergoing fertilization (89-96%) were obtained 9-9.5 h after insemination. With only pyruvate or lactate as substrates, or with both pyruvate and lactate, acrosome reactions occurred in only 2-4% of the sperm. When D-glucose ranging in concentration from 2.78 to 8.34 mM was added, a high proportion (82-95%) of the eggs inseminated were found to be fertilized. Substituting D-galactose, L-glucose, L-fucose, D-lactose, or D-saccharose for D-glucose resulted in very low numbers of acrosome-reacted sperm (0-12%) and fertilized eggs (0-7%). However, in the presence of metabolizable sugars, such as D-mannose or D-fructose, the acrosome reaction was seen in 78-85% of the sperm examined and 87-95% of the eggs tested were fertilized.

Animals↗
PubMed1982

Sperm penetration in vitro of human oocytes matured in a chemically defined medium.

Human oocytes were obtained randomly from the ovaries excised from 28 patients at different stages of the menstrual cycle. When 114 oocytes were cultured for 40-40.5 h in a chemically defined medium 80 showed degeneration. When 16 of the remaining 64 oocytes were examined for their maturation, germinal vesicle breakdown (GVBD) had occurred in 11 oocytes. Another 48 oocytes were inseminated by ejaculated spermatozoa which were washed twice and preincubated for 3 h. When examined 10 h later, 19 (39.6%) were penetrated with an enlarged sperm head or male pronucleus(ei) and its corresponding sperm tail(s).

Adult↗
PubMed1982

Survival of rat embryos after freezing.

The effects of cryoprotectants and freeze-thawing procedures on the survival of frozen rat morulae were examined. In the samples frozen and thawed in the presence of DMSO, ethylene glycol or glycerol, higher proportions of the embryos developed into blastocysts in culture when they were frozen slowly (50--71%) than when they were frozen rapidly (20--39%), but the thawing rates of the slowly frozen samples did not affect the viability of the embryos. When erythritol was used as a cryoprotectant, all of the embryos frozen-thawed slowly were killed but rapidly thawed embryos survived regardless of the freezing rate (36--52%). The morulae frozen slowly with ethylene glycol or glycerol and those frozen rapidly with DMSO or erythritol were transferred to recipients after thawing and full-term young were obtained with all 4 cryoprotectants.

Animals↗
PubMed1982

Purification and action sites of a follicle stimulating hormone inhibitor from bovine follicular fluid.

The purification and action sites of a follicle stimulating hormone (FSH) inhibitor obtained from bovine follicular fluid were examined. Bovine follicular fluid was salted out with ammonium sulfate as a concentration of 14.5 to 18.5%, and the salted out fraction was separated into two peaks by Sephadex G-200 column chromatography. The second peak, detectable as a single band by polyacrylamide gel disc electrophoresis, contained all the inhibitory activity to compensatory ovarian hypertrophy in mice. Serum FSH levels of unilaterally ovariectomized mice given injections of the inhibitor were lower than those of unilaterally ovariectomized mice given injections of saline. The inhibitor also suppressed FSH binding to granulosa cells in vitro. These results suggest that this inhibitor has two modes of action: suppression of FSH levels in serum and suppression of FSH binding to granulosa cells.

Animals↗
PubMed1981

Effects of various cryoprotective agents on the survival of unfrozen and frozen mouse embryos.

The effects of DMSO, ethylene glycol, glycerol, erythritol, dimethylformamide and sucrose on the survival of unfrozen and frozen mouse morulae were examined. All the agents had a deleterious effect on survival of the unfrozen morulae at 20 degrees C. The harmful effect of erythritol was lower at 0 degrees C and sucrose had a protective effect at that temperature. Dimethylformamide and DMSO were more harmful than ethylene glycol and glycerol at both temperatures. Higher proportions of the morulae frozen in DMSO developed into expanded blastocysts when slowly frozen samples were thawed slowly (82%) than when they were thawed rapidly (85%) than when they were thawed slowly (4%). When the samples were frozen in the presence of ethylene glycol or glycerol, higher survival rates were obtained after slow (80--94%) than rapid (1--59%) freezing. When erythritol was used, only embryos thawed rapidly developed (31--50%) in subsequent cultures. Sucrose and dimethylformamide did not afford cryoprotection. Morulae frozen--thawed rapidly in the presence of ethylene glycol, glycerol or erythritol and transferred to recipients developed into normal young.

Animals↗
PubMed1981

Immunosuppressive action of oral Streptococci.

The study on the immunosuppressive activity of the cytoplasmic component (SF) from Streptococcus mitis on the immune response of mice to the sheep red blood cells (SRBC) was carried out. The bacterial cell suspension was disrupted in a Braun shaker. The disrupted cell suspension was diluted and centrifuged at 10,000 x g for 30 minutes to remove the cell walls. The supernatant was centrifuged at 31,000 x g for 45 minutes and the final supernatant was dialyzed against distilled water, frozen and lyophilized. These products were employed as the cytoplasmic component (SF). The SF in the extracts of Streptococcus mitis suppresses the antibody formation in mice against SRBC. It is effective to inject it just one day before the inoculation with SRBC.

Animals↗