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Biomedical subjects

K Eto

Publications and source records attributed to K Eto.

At least 181 records · Page 10Linked to original sources
PubMed1986

Stage-specific response of the mesenchyme to excess vitamin A in developing rat facial processes.

The effects of excess retinol (vitamin A alcohol) on facial process formation were examined in cultured rat embryos. The embryos were explanted at day 11 of gestation (plug day = 0) and cultured for 72 hr in rat serum containing an additional 1 or 10 micrograms/ml retinol. The reduction of outgrowth in the facial processes was observed in 1 microgram/ml retinol-treated embryos, and this type of malformation was found to be more severe in 10 micrograms/ml retinol-treated embryos. Histological findings of 10 micrograms/ml retinol-treated embryos at the 50-somite stage showed that the nasal epithelium was developed but folded. In the mesenchyme, there were necrotic cells. Thymidine incorporation by mesenchymal cells in the facial processes was also determined. At the 50-somite stage, the uptake was decreased to 66.4% of control value at 1 microgram/ml retinol, whereas the addition of the same dose of retinol did not cause the inhibition at the 36-, 40-, and 42-somite stages. The uptake at the 50-somite stage was decreased to 23.0% as a result of the 10 micrograms/ml retinol treatment. These results show that the response of the facial mesenchyme to excess retinol is dependent on the development stage and the critical stage of the facial mesenchyme for excess retinol in cultured rat embryos is the 42-somite stage.

Animals↗
PubMed1985

Light and electron microscopy study of fusion of facial prominences. A distinctive type of superficial cells at the contact sites.

The contact site between the medial nasal prominence (MNP) and the lateral nasal prominence (LNP) during the period of primary palate formation in the mouse embryo was examined by light and electron microscopy. Throughout this period, a distinctive type of superficial cell was observed at the contact site. These superficial cells had a large nucleus and abundant cytoplasm as well as structural features characteristic of embryonic cells. At earlier stages, these cells were seen at the transitional region between the surface ectoderm and the epithelia of the nasal pit at the end of the isthmus, where initial contact of opposing MNP and LNP took place. At later stages, these superficial cells appeared to bridge the gap between MNP and LNP at the contact sites, which extended to the bottom of the valley formed by MNP and LNP. These cells were also observed on the surface near the contact sites, that is, the presumptive fusion area. These superficial cells displayed well-developed junctional complexes (intermediate and gap junctions, and desmosomes). Many filaments were observed subjacent to the plasma membranes of these superficial cells, some of which were associated with junctional complexes. These observations suggest that this kind of distinctive superficial cell may play critical roles in the contact of MNP and LNP throughout the fusion process.

Animals↗
PubMed1985

Effect of tricyclic drugs on mitochondrial membrane.

The effects of tricyclic drugs (clomipramine, imipramine, chlorpromazine and promethazine) on isolated liver mitochondria of rats were examined. All the drugs tested accelerated state 4 respiration. Their stimulative potency at concentrations below 100 microM was in the order of chlorpromazine greater than clomipramine greater than imipramine, promethazine. On state 3 respiration, the chlorine containing drugs had an inhibitive effect at high concentrations, while the other drugs seemed to have a slightly stimulative effect. These drugs stimulated latent ATPase activity of mitochondria. Clomipramine and chlorpromazine inhibited 2, 4-dinitrophenol-stimulated ATPase activity in a dose-dependent fashion. Imipramine also inhibited 2, 4-dinitrophenol-stimulated ATPase activity at high concentrations. Promethazine, however, had almost no effect. All the drugs induced potassium release from mitochondrial vesicles, and their potency was in the order of clomipramine greater than chlorpromazine greater than imipramine greater than promethazine. These results suggest that clomipramine, imipramine, chlorpromazine and promethazine cause impediments in both mitochondrial respiration and ion compartmentation, and that the chlorine containing drugs are more toxic than others on the functions of the mitochondrial membrane.

Adenosine Triphosphatases↗
PubMed1985

Embryotoxic effects of EGTA-induced hypocalcemic condition on cultured rat embryos.

EGTA-treated rat serum was added to the culture medium and tested the toxic effect of EGTA on development of embryo using 11.5-day-old embryo in vitro. Exposure of the embryo to the medium treated with 25 micrograms/ml of EGTA for 2 or 24 hours caused a variety of teratogenic effects such as tail and hind limb bud deformities and facial anomalies (cleft lip). At a higher concentration of EGTA (50 micrograms/ml), damage of yolk sac (shrinkage type), developmental anomalies and dead fetuses were frequently observed. Embryonic growth and differentiation were only moderately affected under any experimental conditions. Calcium levels in EGTA-treated culture medium at doses of 25 and 50 micrograms/ml were significantly reduced as compared to the non-treated medium. These results suggested that the teratogenic action of EGTA is closely related to the decrease of calcium level in the medium.

Abnormalities, Drug-Induced↗
PubMed1985

Improved development of rat embryos in culture during the period of craniofacial morphogenesis.

To study the mammalian craniofacial development, the culture conditions of rat whole embryo during the period of major craniofacial morphogenesis were examined. The improved rotating apparatus which is gassed continuously was used. Rat embryos explanted at 11.5 days (plug day 0) developed in vitro for up to 72 hr, that is, throughout the period of major craniofacial morphogenesis, and cultured embryos showed normal facial formation. The medium was equilibrated with a gas mixture of 95% 02, 5% CO2. The 100% rat serum improved the protein content of embryos cultured for 48 hr compared with the medium consisting of 50% rat serum and 50% Tyrode solution, although somite number was not altered. Furthermore, 100% rat serum containing 2 mg/ml glucose was the best medium for supporting growth of embryos when it was measured by protein content. Thus, the best culture medium was pure rat serum containing 50 units/ml penicillin, 50 micrograms/ml streptomycin, and 2 mg/ml glucose. Protein content, body weight, craniofacial formation, and somite number of embryos cultured for 48 hr with continuous gassing were much better than those cultured with noncontinuous gassing.

Animals↗
PubMed1985

The role of the yolk sac in craniofacial development of cultured rat embryos.

To study the role of the yolk sac and amnion in craniofacial development, the effects of opening the yolk sac and amnion on facial formation of rat embryos were examined in vitro. Rat embryos were cultured for 72 hr from day 11.5 of gestation using an improved rotation apparatus. In experiments, the yolk sac and amnion were opened at the time of explantation (day 11.5) in one group (D11 open) and were opened 24 hr after the beginning of the culture (day 12.5) in another group (D12 open). Cleft lip developed in 100% of cultured embryos when the yolk sac and amnion were opened at day 11.5 (D11 open). In the D12 open group, however, cleft lip occurrence decreased to 3.0%. Protein content, wet weight, and somite number of cultured embryos were not significantly different in the two groups. The results of this study demonstrate that it is beneficial to open the yolk sac and amnion after 24 hr in culture for normal facial formation of rat embryo cultured from day 11.5 of gestation.

Amnion↗
PubMed1984

Teratogenicity of aspirin and its metabolite, salicylic acid, in cultured rat embryos.

Rat embryos were exposed to aspirin or its metabolite, salicylic acid in culture. In these embryos acute reduction of heart beat was observed during 4 hours of administration compared to that in non-treated one. Protein contents and crown-rump length of cultured embryos were significantly decreased in aspirin-treated group, but were not so decreased in salicylic acid-treated one. The predominant defects of the embryos exposed to aspirin were edematous facial malformations and abnormality of tail. On the other hand, facial anomalies such as cleft lip and curly tail were observed in the embryos cultured with salicylic acid. Anomalies induced by aspirin were systemic, while salicylic acid induced localized malformations. These results might be due to the differences between aspirin and its metabolite, salicylic acid in their teratogenicity.

Abnormalities, Drug-Induced↗
PubMed1983

Effects of irradiation on grafted skin.

The reaction of grafted skin to irradiation was studied in the rat and the optimum time for irradiation postoperatively was determined. There was a close correlation between the radiosensitivity and the vascularity of the graft and its recipient bed. Grafts showed different reactions depending on the time of irradiation after grafting. Those in the early hypovascular stage showed reactions similar to those of normal control skin. Severe reactions were observed in the hypervascular stage. Grafts in the late hypovascular stage showed more moderate reactions.

Animals↗
PubMed1983

[An experimental study on electrophysiological and histopathological changes in 2,5-hexanedione-intoxicated rats].

An experimental study of neuropathy due to 2,5-hexanedione (2,5-HDione) was performed in rats by using simultaneously both electrophysiological and histopathological methods. Seven rats were given subcutaneously five days a week 200 mg/kg of 2,5-HDione for first 3 weeks and then 300 mg/kg for the next 5 weeks. Nerve conduction velocities in the tail were measured every week and after the respective measurement times one animals was sacrificed for histological study. At the 2nd week of the experiment, 2,5-HDione-treated rat showed a slight morphological changes with swollen axons in the posterior spinal root fiber and tail nerve. A slowing of motor and sensory conduction velocity (MCV and SCV) in the tail was observed in the treated group at the 4th week. Weakness of hindlimbs was apparently seen at the 5th week. At the 6th and 7th week, histological changes including giant axonal swelling, fiber loss, thinning of myelin and demyelination, were prominent in the various regions of the peripheral nervous system. Additionally, degenerative changes of the spermatogenic cells, especially the formation of multinucleated giant spermatids, were markedly observed in the treated rats at the 6th and 7th week.

Animals↗