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Biomedical subjects

N Satoh

Publications and source records attributed to N Satoh.

At least 325 records · Page 18Linked to original sources
PubMed1985

Inhibition of platelet aggregation by synthetic phosphatidylcholines: possible involvement of vesiculation of platelet plasma membranes.

Synthetic phosphatidylcholines inhibited thrombin-induced aggregation of rabbit platelets. The inhibitory effect of the phosphatidylcholines increased with an increase in the chain-length of the constituent fatty acids up to 12, and then decreased, and C14:0PC and C16:0PC did not inhibit platelet aggregation. The activity of synthetic phosphatidylcholines as to induction of vesiculation of platelet plasma membranes (Kobayashi, T., Okamoto, H., Yamada, J.-I., Setaka, M. and Kwan, T. (1984) Biochim. Biophys. Acta 778, 210-218) and the inhibitory effect of these phosphatidylcholines on platelet aggregation showed the same dependence on the constituent fatty acids of the phosphatidylcholines. The amounts of phosphatidylcholines required for 50% inhibition of platelet aggregation correspond very well to those required for 15% exfoliation of acetylcholinesterase activity, suggesting that there is a close relationship between platelet aggregation and vesiculation of the platelet plasma membrane. The possible mechanism of inhibition of platelet aggregation by synthetic phosphatidylcholines is discussed.

Acetylcholinesterase↗
PubMed1985

An autopsy case with Good's syndrome and dermatomyositis.

A 31-year-old male patient complaining of repeated respiratory infections was revealed to be in an immunodeficient state in both humoral and cellular immunity and accompanied by dermatomyositis which was proved by both clinical and histological findings. Persistent diarrhea followed by colonic bleeding due to multiple ulcers and a severe liver dysfunction seemed to bring him to his death. The autopsy revealed the presence of thymoma of spindle cell type, depleted cells in the systemic lymphatic systems and inflammatory lesions in the muscle, liver, lung, kidney and gastrointestinal tract. This is the first report of Good's syndrome accompanied by dermatomyositis.

Adult↗
PubMed1985

Cell lineage analysis in ascidian embryos by intracellular injection of a tracer enzyme. II. The 16- and 32-cell stages.

Cell lineages during development of ascidian embryos were analyzed by injecting horseradish peroxidase as a tracer enzyme into identified cells of the 16-cell and 32-cell stage embryos of Halocynthia roretzi. Most of the blastomeres of these embryos developed more kinds of tissues than have hitherto been reported, and therefore, the developmental fates of each blastomere are more complex. It has been thought that every blastomere of the 64-cell stage ascidian embryo gives rise to only one kind of tissues, but the finding that the several blastomeres at the 32-cell stage developed into at least three different kinds of tissues, clearly indicates that the stage at which the fates of every blastomere are determined to one tissue is later than the 64-cell stage. The results also clearly demonstrate that muscle cells are derived not only from B-line cells (B5.1, B5.2, B6.3, and B6.4) but also from A-line cells (A5.2 and A6.4) and b-line cells (b5.3 and b6.5). Based on the present analysis as well as other studies, complete cell lineages of muscle cells up to their terminal differentiation have been proposed. In addition, lineages of nervous system, notochord, and epidermis are also discussed.

Animals↗
PubMed1985

Protein tyrosine kinase activity of eggs of the sea urchin Strongylocentrotus purpuratus: the regulation of its increase after fertilization.

Protein tyrosine kinase activity in eggs of the sea urchin, Strongylocentrotus purpuratus, increased two- to fourfold as early as several min after fertilization at 8-10 degrees C. Artificial activation of eggs with the divalent cation ionophore, A23187, or with butyric acid induced the increase in enzyme activity. The transfer of eggs to seawater containing either no Na+ or 50 mM Na+ and 10(-4) M amiloride immediately after fertilization did not block the increases in enzyme activity. When eggs were activated with seawater containing NH4OH, enzyme activity did not increase at 1 hr after activation, although the increased activity was detected at 3 hr after activation. Increased enzyme activity also was observed in enucleated egg fragments activated with butyric acid. Puromycin and emetine, inhibitors of protein synthesis, also did not inhibit the initial increases of enzyme activity after fertilization. These results demonstrated that the increased protein tyrosine kinase activity observed after fertilization of S. purpuratus eggs can be initiated independent of various other known events such as fusion with sperm cells and protein and DNA synthesis.

Butyrates↗
PubMed1985

Recent advances in our understanding of the temporal control of early embryonic development in amphibians.

Recent studies on temporal control of early amphibian development are reviewed. It is becoming clear that the development of an embryo is not timed by a single clock set in motion at fertilization, instead each developmental event seems to be timed by its own clock-like mechanism. The timing of developmental events is rigidly determined within embryonic cells, and usually can not be altered experimentally. One exception, however, is the timing of midblastula transition in amphibian embryos; recent studies have shown that its timing is regulated by the nucleocytoplasmic ratio. Several developmental events, particularly those associated with transcriptional activities, require DNA replication prior to their occurrence, suggesting an intimate relationship between DNA replication cycles and their onset. On the other hand, there are many other developmental events where timing is not controlled by the number of cell divisions, DNA replication cycles, or the nucleocytoplasmic ratio. Cytoplasmic machinery with autonomous oscillatory properties is thought to be involved in the timing of these events.

Ambystoma↗
PubMed1985

Histospecific acetylcholinesterase development in the presumptive muscle cells isolated from 16-cell-stage ascidian embryos with respect to the number of DNA replications.

The presumptive muscle cells (B5.1 blastomeres) were isolated from 16-cell-stage embryos of the ascidian, Ciona intestinalis. The isolated cells were allowed to divide either twice or three times thereafter. Then further divisions of the cells were continuously inhibited by a simultaneous treatment with aphidicolin (a specific inhibitor of DNA synthesis) and cytochalasin B (an inhibitor of cytokinesis). When development of muscle-specific acetylcholinesterase in these division-arrested progeny cells of B5.1 blastomeres was examined histochemically, the B5.1 blastomeres which had been allowed two further divisions did not produce any detectable acetylcholinesterase activity. Whereas those which had been allowed three further divisions showed the tissue-specific enzyme activity. These results provide further evidence for the presence of a quantal DNA replication cycle for the tissue-specific enzyme development, which is qualitatively different from the other DNA replication cycles.

Acetylcholinesterase↗
PubMed1984

Three-dimensional distribution of vasoactive intestinal polypeptide-containing structures in the rat stomach and their origins using whole mount tissue.

The three-dimensional distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactive (VIPLI) structures in rat stomach and their origins were investigated using the indirect immunofluorescence method in whole mounted tissue. The present study demonstrates a very dense VIPLI fiber meshwork in the circular muscle layer, longitudinal muscle layer and myenteric plexus. In the muscle layers VIPLI immunoreactive fibers run parallel to the muscle. VIPLI fibers are distributed evenly throughout the entire stomach. We have also shown by experimental manipulations that the fibers in the stomach originate from VIPLI neurons in the myenteric plexus.

Animals↗
PubMed1984

Autonomous muscle cell differentiation in partial ascidian embryos according to the newly verified cell lineages.

Recent analysis of cell lineages in ascidian embryos by the intracellular injection of a tracer enzyme has clearly demonstrated that muscle cells are derived not only from the B4.1-cell pair of the eight-cell stage embryo, as has hitherto been believed, but also from both the b4.2- and A4.1-cell pairs (H. Nishida and N. Satoh, 1983, Dev. Biol. 99, 382-394). In order to reexamine the developmental autonomy in muscle lineage cells, the B4.1 pair was isolated from the eight-cell stage embryo. The progeny cells of the B4.1 pair, as well as those of the six other blastomeres, were then allowed to develop in isolation into partial embryos. Autonomous muscle cell differentiation not only in partial embryos originating from the B4.1 cells but also in those from the six other blastomeres was substantiated by (a) occurrence of localized histospecific muscle acetylcholinesterase and (b) development of myofibrils. These results support the validity of the recent cell lineage study and confirmed the self-differentiation potency of muscle lineage cells in ascidian embryos according to the newly verified cell lineages.

Acetylcholinesterase↗
PubMed1984

Periodic appearance and disappearance of microvilli associated with cleavage cycles in the egg of the ascidian, Halocynthia roretzi.

The surface of eggs of the ascidian Halocynthia roretzi, observed with SEM, is essentially smooth until immediately before cell division when numerous microvilli appear and remain during cytokinesis. As the dividing blastomeres become closely adherent, however, the microvilli disappear and the eggs recover their smooth surface. This periodic appearance-disappearance of microvilli is repeated at each cleavage cycle up to at least the 32-cell stage. During blastomere adhesion, microvilli that have appeared near the plane of the first cleavage or of the bilateral symmetry seem to fuse together across the plane to form a zipper-like complex of cytoplasmic processes, which might be responsible for attachment of the two halves of these bilaterally symmetrical embryos via the blastomeres bordering the plane of symmetry.

Animals↗
PubMed1984

Embryoid bodies cultured in in vivo diffusion chambers show reduced tumorigenicity while retaining expression of F9 antigens.

Embryoid bodies of the mouse teratocarcinoma OTT6050 were dissociated into single cells and cultured in diffusion chambers implanted into the peritoneal cavities of mice. The syngeneic host mice, into which the cells of embryoid bodies cultured in the diffusion chambers had been injected, survived much longer than those which received the original cells of embryoid body. But in the case of the F9 cells, obtained in the same culture conditions, only a slight decrease in tumorigenicity was observed. By contrast, the F9 antigenic expression was observed on both F9 and embryoid body cells cultured in diffusion chambers. Judging from the determination of adult-type antigenic expressions, the differentiation of the cells in chamber was negligible. These results suggest that the tumorigenic activity of the embryoid body cells cultured in vivo in a diffusion chamber is almost suppressed, but that they continue in an undifferentiated state.

Animals↗
PubMed1984

[The interaction of oxytocin-prostaglandin receptors in human myometrium and amnio-decidua throughout pregnancy and in labor].

This study was designed to investigate the interaction of oxytocin and prostaglandin F2 alpha at the receptor level (OXT-R and PGF2 alpha-R) between the myometrium and amnio-decidua throughout pregnancy and at parturition in an effort to clarify which of the two is the first and/or triggering factor involved in the instigation of myometrial contractions. In rat myometria, it was recognized that PGF2 alpha-R increased from day 20 of pregnancy and preceded that of OXT-R from day 22 and thereafter both reached peak levels at delivery. In human myometria, on the other hand, OXT-R showed an increase as gestation advanced and when labor was initiated, a significant decrease was found regardless of the route of labor, while the PGF2 alpha-R the binding capacity of which was only 1/20-1/30 of OXT-R, did not change throughout pregnancy or in labor. The binding affinity of OXT-R in amnio-decidua increased as gestation advanced, while its binding capacity remained unchanged and after the onset of labor that of the amnion decreased significantly even though it was only 1/6-1/7 that of the myometrium. The binding affinity of myometrial OXT-R was elevated following the addition of PGF2 alpha before the onset of labor, but the converse could not be shown. These findings suggest that the instigation and maintenance of human labor may be firstly and/or initially dependent on the increase of the binding activity between OXT and OXT-R in the myometrium, and the PGF2 alpha may facilitate such activity by the allosteric effect on OXT-R directly or on the plasma membrane to increase its binding affinity.

Amnion↗