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Biomedical subjects

M Onodera

Publications and source records attributed to M Onodera.

At least 73 records · Page 4Linked to original sources
PubMed1989

Parthenogenetic activation of mouse and rabbit eggs by electric stimulation in vitro.

The present study was undertaken to determine conditions for parthenogenetic activation of mouse and rabbit eggs by electric stimulation in vitro. The cumulus-free eggs were submitted to square direct current pulses at output voltage of 1.0 to 2.5 kV/cm for 25 to 200 microseconds. The best conditions for the activation of mouse eggs were 1.5 kV/cm for 100 microseconds, in which 78% of eggs were activated, 32% of which developed to blastocysts in vitro. When the nonelectric solution (0.3M mannitol) was used for electric stimulation, the activation rate was quite low (16%). Optimal conditions for activation of rabbit eggs were 1.5 kV/cm for 200 microseconds, in which 77% of eggs were activated, 25% of which developed to blastocysts. Unlike mouse eggs, rabbit eggs frequently had three pronuclei after electric stimulation. It is clearly shown that electric stimulus can induce parthenogenetic activation of the mouse and rabbit eggs in vitro.

Animals↗
PubMed1989

Effect of the administration of cycloheximide to thioacetamide-primed rats or partial-hepatectomized rats on the RNA polymerase I activity in isolated nuclei of liver.

1. Twenty-four hours after administration of thioacetamide to normal rats, the activity and amount of RNA polymerase I in isolated liver nuclei were almost doubled. 2. When cycloheximide was administered to the drug-treated rats and normal rats 1 or 2 hr before death, the reduction in the activity was of the same degree, that is, about half of the activity of liver nuclei from normal rats. 3. Partial hepatectomy also caused about 2-fold increase in the RNA polymerase I activity in isolated liver nuclei after 16 hr, but the increased activity was almost completely abolished by injection of cycloheximide 1-3 hr before killing.

Acetamides↗
PubMed1989

[Influence of pregnancy and steroid hormones on interferon production of lymphocytes].

A study was done to investigate the involvement of interferon (IFN) in immunological acceptance of fetal allograft. IFN was induced by stimulating OK-432 from lymphocyte of pregnant and nonpregnant women as well as men. There was no difference in the IFN titer in these groups. In pregnant women there was no difference between trimesters, either. In addition, we examined the influence of sex steroid hormones such as progesterone and estrogen on IFN production by the lymphocytes of women and men. Generally, each steroid hormone suppressed the production of IFN. However, the extent of suppression varied with the concentration of hormones, resulting in different suppression curves for men and women in a physiological concentration. Differences in response by men and women were also noticed when interleukin 2 was added to examine whether it could reduce the suppression by steroid hormone. This unique sensitivity of female lymphocyte to steroid hormones may play a role in successfully taking a fetal allograft in pregnancy.

Adult↗
PubMed1988

Differential sensitivity of mouse pronuclei and zygote cytoplasm to Hoechst staining and ultraviolet irradiation.

The exposure of mouse zygotes pre-stained with Hoechst 33342 to u.v. irradiation for 20-30 sec significantly or completely inhibited development to blastocysts in vitro. However, development to the blastocyst stage of enucleated eggs receiving pronuclei from untreated eggs was as good as that of control reconstituted eggs when the cytoplasm originated from eggs exposed to u.v. irradiation for 20-30 sec, but was significantly lower when the cytoplasm was from eggs exposed for 40 sec. The chromosomes at the second metaphase stage could be removed with 15 sec of exposure to u.v. irradiation under a fluorescence microscope. Most eggs enucleated at the second metaphase that received a single inner cell mass nucleus (75%) showed pronuclear formation 6 h after activation; 23% of them developed to morphologically normal 2-cell eggs and 5% developed to blastocysts. These results demonstrate that the cytoplasm of mouse zygotes is more resistant to u.v. irradiation after Hoechst staining. Eggs at the second metaphase, from which chromosomes have been removed under a fluorescence microscope, can therefore be used as cytoplasm recipients for nuclear transplantation of inner cell mass nuclei.

Animals↗
PubMed1985

Involvement of suppressor cells induced with membrane fractions of trypanosomes in immunosuppression of trypanosomiasis.

We showed that infection with Trypanosoma congolense in mice led to suppression of listeria-induced delayed type hypersensitivity (DTH). Mice were pre-treated with irradiated T. evansi, which caused rapid and effective suppression of DTH. A membrane fraction obtained by homogenizing T. evansi variant in a hypotonic buffer solution and centrifuging it at 150,000g produced suppression of listeria-induced DTH when injected i.p. into mice as early as 1 day before listeria immunization. Furthermore, we demonstrated by an adoptive transfer system that the suppressor cells involved in this suppression had developed in the spleen and that the activity of the splenic suppressor cells was due to the presence of a macrophage population.

Animals↗
PubMed1983

Determination of prostaglandin E2 and the main prostaglandin E metabolite by micro high-performance liquid chromatography using fluorescence derivatization with dansyl hydrazine.

A micro high-performance liquid chromatographic method for the determination of prostaglandin E2(PGE2) and the main prostaglandin E metabolite (PGEMT) in rat organs and human urine has been developed. Prednisolone was added to the sample as the internal standard. The isolated PG's and the internal standard were subjected to reaction with dansyl hydrazine, separated by liquid chromatography on a mu Fine pack SIL C18 and determined fluorimetrically. The standard deviation of the method was +/- 6.5% for PGE2, and +/- 8.4% for PGEMT. The detection and simultaneous quantitation of less than 10 ng of PGE2 and PGEMT is possible. The proposed method is suitable for the pharmacological analysis of PGE2 and PGEMT in various rat tissues and human urine.

Animals↗
PubMed1983

Properties of three creatine kinases MM from porcine skeletal muscle.

The properties of three fractions (FI, FII, and FIII) of porcine creatine kinase MM, which have been isolated by isoelectric focusing, were compared. Sugars were not detected in them. Their carboxyl-terminal sequences were identical and were determined to be -Thr-Lys by digestion with carboxypeptidases A and B. Immunodiffusion and competitive radioimmunoassay could not differentiate the three fractions from one another. Their amino-terminal sequences revealed that they had different primary structures. At residue 1, although all the three fractions had Pro, FI and FIII had an additional amino acid, Ser. At residue 23, only FI had Leu in addition to Ser, the amino acid common to the three fractions. These results indicate that differences among the three fractions of porcine creatine kinase MM are based on differences in the primary structures of the subunits in their dimer structures, and confirm the conclusion that FII is a homodimer and FI and FIII are heterodimers, which was reported in the preceding paper [Takasawa, T. & Shiokawa, H. (1983) J. Biochem. 93, 383-388].

Amino Acid Sequence↗
PubMed1981

[The protective effect of vitamin E on the hepatotoxic effects of CS2 in male albino rats of Wistar strain (author's transl)].

In Vitamin E deficient rats, which had received an oral CS2 administration of the dose at 1 mg/kg following a peritoneal injection of phenobarbital sodium and a fasting period of 24 hours, histopathological changes such as vacuolar degeneration and fatty infiltration of the liver were observed along with the increases in liver weight and liver/body weight ratio. On the other hand, no such effects could be found in Vitamin E supplemented rats which otherwise received the same treatment as the Vitamin E deficient group.

Alanine Transaminase↗
PubMed1981

Antigenic variation and the surface glycoproteins of Trypanosoma congolense.

Two Trypanosoma congolense variant-specific glycoproteins, which are expressed sequentially during a relapsing infection, have been purified. The proteins, termed VSG-1 and VSG-2, both have a molecular weight of 53,000 as determined by SDS polyacrylamide electrophoresis. When either antigen is electrophoresed through a pH gradient on an isoelectric focusing (IEF) gel, it gives a characteristic spectrotype of three bands. The IEF components of each VSG are antigenically similar to each other but not identical. The components of VSG-1 are immunologically distinct from the components of VSG-2, as shown by lack of cross-reactivity. The three spectrotypes may reflect microheterogeneity in amino acid sequence among the components. Both VSG-1 and VSG-2 are selectively cleaved by trypsin near their carboxy-terminal ends, indicating the existence of a possible common VSG region. Significant homology in the aminoterminal amino acid sequences of VSG-1 and VSG-2 suggests that sequentially reduplicated genes are sequentially expressed by trypanosomes during relapsing infections.

Amino Acid Sequence↗