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Biomedical subjects

N Satoh

Publications and source records attributed to N Satoh.

At least 343 records · Page 19Linked to original sources
PubMed1983

Cell lineage analysis in ascidian embryos by intracellular injection of a tracer enzyme. I. Up to the eight-cell stage.

Cell lineages during development of ascidian embryos were analyzed by injection of horseradish peroxidase as a tracer enzyme into identified cells at the one-, two-, four-, and eight-cell stages of the ascidians, Halocynthia roretzi, Ciona intestinalis, and Ascidia ahodori. Identical results were obtained with eggs of the three different species examined. The first cleavage furrow coincided with the bilateral symmetry plane of the embryo. The second furrow did not always divided the embryo into anterior and posterior halves as each of the anterior and posterior cell pairs gave rise to different tissues according to their destinies, which became more definitive in the cell pairs at the eight-cell stage. Of the blastomeres constituting the eight-cell stage embryo, the a4.2 pair (the anterior animal blastomeres) differentiated into epidermis, brain, and presumably sense organ and palps. Every descendant cell of the b4.2 pair (the posterior animal blastomeres) has been thought to become epidermis; however, the horseradish peroxidase injection probe revealed that the b4.2 pair gave rise to not only epidermis but also muscle cells at the caudal tip region of the developing tailbud-stage embryos. The A4.1 pair (the anterior vegetal blastomeres) developed into endoderm, notochord, brain stem, spinal cord, and also muscle cells next the caudal tip muscle cells. From the B4.1 pair (the posterior vegetal blastomeres) originated muscle cells of the anterior and middle parts of the tail, mesenchyme, endoderm, endodermal strand, and also notochord at the caudal tip region. These results clearly demonstrate that muscle cells are derived not only from the B4.1 pair, as has hitherto been believed, but also from both the b4.2 and A4.1 pairs.

Animals↗
PubMed1983

Spin label measurement of platelet alignment in a clot induced by isometric tension.

A spin label technique was applied to examine the alignment of platelet membranes in the platelet-fibrin clot. The ESR spectrum of the clot in the control experiment was typical of isotropically oriented membranes, while the ESR spectrum of the clot which was kept isometric was quite different from that of the control experiment. These spectra were simulated with a computer and explained to indicate that the shape of platelets in the clot was transformed to a cylindrical form under the isometric tension so that axes of all membrane cylinders were directed parallel to the generated force.

Animals↗
PubMed1982

Timing of gastrulation in fused double-embryos formed from eggs with different cleavage schedules in the starfish, Asterina pectinifera.

The aim of this study is to explore the control mechanism which regulates the timing of gastrulation. We wished to know whether the timing is rigidly determined within the constituting cells of the embryo of whether it is changed by intercellular communication systems. Starfish-fused double-embryos were formed by contact between pairs of denuded eggs with different cleavage schedules, one egg in each pair being distinguished with vital stain. Electron microscopy revealed identical ultrastructural characteristics in every cell contact: Septate junctions were found not only between cells in the contact area between the two counterparts constituting a fused embryo but also between cells within a counterpart. In fused embryos formed from stained eggs and unstained eggs with the former having started the first cleavage 30 min earlier than the latter, the stained counterparts began to invaginate about 30 min earlier than the unstained. When fused embryos were produced by putting stained eggs in contact with unstained eggs which had begun the first cleavage 2 hr later than the stained eggs, gastrulation of the stained counterparts took place about 2 hr earlier than that of the unstained counterparts. These results suggest that the timing of gastrulation is fixed within the cells of an embryo and cannot be altered in spite of the cell-to-cell communication that appears to exist.

Animals↗
PubMed1982

Orientation of platelets on the surfaces of glass and Teflon plates as studied by a spin label technique.

Platelets were found by a spin label technique to orient on flat surfaces of glass as well as of Teflon. This kind of platelet orientation was not caused by centrifugation or partial dehydration of the membrane preparation as employed usually to make oriented planar multilayers of biological membranes on the surface of a supporting plate (1-8), but was considered to be closely related to the adhesion or the aggregation properties of platelets. The amount of oriented platelets varied depending on the platelet treatment and was estimated from a computer simulation of the observed ESR spectra to be about one-half of that of the non-oriented ones in the case of thrombin-treated platelets. This technique may be useful as a new tool to explore the adhesion or aggregation properties of platelets.

Animals↗
PubMed1982

DNA replication is required for tissue-specific enzyme development in ascidian embryos.

Tyrosinase which is a tissue-specific enzyme in the pigment cells of the brain of the ascidian embryo, is thought to be synthesized with activation of appropriate genes, and the enzyme synthesis begins at the early tailbud stage. If embryos at early cleavage stages up to the 64-cell stage are continuously treated with aphidicolin (a specific inhibitor of DNA synthesis), cleavage of the embryos is arrested and they do not differentiate the enzyme. However, the early gastrulae and embryos at later stage that have been permanently arrested with aphidicolin do produce the enzyme. Alkaline phosphatase, a tissue-specific enzyme of the endodermal cells, has been shown to be synthesized by a preformed maternal mRNA and is first detected histochemically at the late gastrula stage. If embryos at early cleavage stages up to the 16-cell stage are prevented from undergoing further divisions with aphidicolin, the arrested embryos do not form the enzyme. However, embryos at the 32-cell and later stages that have been permanently arrested with aphidicolin are able to differentiate the enzyme activity. These results suggest that several DNA replications are required for the histospecific enzyme development in ascidian embryos.

Alkaline Phosphatase↗
PubMed1982

Timing mechanisms in early embryonic development.

Embryological development takes place in four dimensions and requires the existence of time measuring processes within the embryo. Evidence is accumulating that suggests that the emergence of many events during early embryonic development is controlled by timing mechanisms or developmental clocks. The purpose of this work is to review recent studies on developmental timing with speculations about underlying possible mechanisms. It is an attractive idea that the development of an embryo is timed by a single clock set in motion at fertilization, but this seems not feasible. The clock mechanism which determines the time of initiation of cellular differentiation may be independent of that for the timing of morphogenesis. The clock mechanism for cellular differentiation may be closely associated with the cycles of DNA replication, while the clock which counts the time to onset of early morphogenetic events is found in the cytoplasm. These ideas can provide a framework which may help to organize existing observations and to stimulate new experimental approaches to the problem.

Acetylcholinesterase↗
PubMed1982

Immunohistochemical detection of pregnancy-specific protein (SP1) and placenta-specific tissue proteins (PP5, PP10, PP11 and PP12) in ovarian adenocarcinomas.

By using an immunoglobulin-enzyme bridge method, pregnancy-specific beta 1-glycoprotein (SP1) and placenta-specific tissue proteins (PP5, PP10, PP11, PP12) were investigated in 15 cases of mucinous cystadenocarcinoma and 20 cases of serous cystadenocarcinoma. These proteins could be detected in the cytoplasm of some malignant cells. In mucinous cystadenocarcinomas, SP1, was present in 53.3% of cases, PP5 in 80.0%, PP10 in 20.0%, PP11 in 66.7% and PP12 in 46.7%. In serous cystadenocarcinomas, SP1 was present in 35.0% of cases, PP5 in 76.2%, PP10 in 9.5%, PP11 in 57.1% and PP12 in 23.8%. No proteins were detected in five normal ovaries. All control sections incubated with phosphate-buffered saline or normal, non-pregnant, non-immune rabbit serum in place of the first specific antiserum as well as with the antisera exhaustively absorbed with the corresponding purified antigens were negative for each protein. The detection rates are discussed in relation to the clinical stages and survival rates of the patients. This study suggests that these proteins, especially PP5 and PP11, may be useful as markers in monitoring patients with ovarian adenocarcinomas as well as for their early diagnosis.

Cystadenocarcinoma↗
PubMed1981

A definite number of aphidicolin-sensitive cell-cyclic events are required for acetylcholinesterase development in the presumptive muscle cells of the ascidian embryos.

In order to determine whether or not a crucial number of DNA replications are prerequisite for cellular differentiation, we have studied development of a tissue-specific enzyme, muscle acetylcholinesterase (AChE) in the presumptive muscle cells of cleavage-arrested ascidian embryos. Embryos were cleavage-arrested with cytochalasin B (an inhibitor of cytokinesis) and aphidicolin (an inhibitor of DNA synthesis). The 64-cell-stage embryos which had been permanently cleavage-arrested with cytochalasin B developed AChE in all the eight presumptive muscle cells, but the same stage embryos which had been prevented from undergoing further divisions by simultaneous treatment with aphidicolin and cytochalasin did not produce AChE at all. Cytochalasin-arrested 76-cell-stage embryos were able to differentiate AChE in the ten presumptive muscle cells, while aphidicolin-cytochalasin-arrested 76-cell stages in as many as four cells. The early gastrulae which had been arrested with cytochalasin B produced AChE in all the sixteen presumptive muscle cells, while the same stage embryos arrested with aphidicolin and cytochalasin in as many as twelve cells. Cytochalasin-arrested late gastrulae developed AChE in twenty blastomeres, while aphidicolin-cytochalasin-arrested late gastrulae in eighteen cells. The presumptive muscle cells at these four stages consist of three different (seventh, eighth, and ninth) generations, and the relative positions of the blastomeres in the cleavage-arrested embryos remained fixed. Judging from the relative positions of the blastomeres, the AChE-producing cells in aphidicolin-cytochalasin-arrested embryos were always at eighth or ninth generation, while those with no AChE activity were certainly at seventh generation. Based on these findings it was supposed that aphidicolin-sensitive cell-cycle events, presumably DNA replication, are closely associated with AChE development and that the eighth cleavage cycle may be 'quantal' for the histospecific enzyme development.

Acetylcholinesterase↗
PubMed1981

On the 'clock' mechanism determining the time of tissue-specific enzyme development during ascidian embryogenesis. II. Evidence for association of the clock with the cycle of DNA replication.

Acetylcholinesterase (AChE) is a tissue-specific enzyme of the muscle cells of ascidian embryos and its synthesis begins at the neurula stage. Embryos which had been permanently cleavage-arrested with cytochalasin B could develop AChE activity. The time of first AChE occurrence in embryos which had been arrested in the 32-cell stage with cytochalasin was about the same as in normal embryos. The nucleus in the cell of cytochalasin-arrested embryos divided in good synchrony with that of normal embryos. Embryos which had been continuously arrested with colchicine could also produce AChE activity at nearly the same time as did normal embryos. In the cell of colchicine-arrested embryos normal nuclear divisions did not occur, but the cell showed repeated cycles of nuclear envelope breakdown and nuclear envelope reformation in almost parallel with cell cycles of normal embryos. The cell of colchicine-arrested embryos incorporated [3H]thymidine. Aphidicolin, a specific inhibitor of DNA synthesis, prevented cleavages of ascidian eggs. Embryos which had been permanently arrested with aphidicolin in the cleavage stages up to the 64-cell stage did not develop AChE activity, while embryos which had been treated with it from the 76-cell stage onwards were found to be able to differentiate AChE activity. Based on these findings it was proposed that DNA replication is prerequisite for development of the histospecific protein and that the cycle of DNA replication is closely associated with the clock mechanism which is determining the time of initiation of the enzyme development.

Acetylcholinesterase↗
PubMed1979

On the 'clock' mechanism determining the time of tissue-specific enzyme development during ascidian embryogenesis. I. Acetylcholinesterase development in cleavage-arrested embryos.

During ascidian embryogenesis a tissue-specific enzyme, muscle acetylcholinesterase (AChE) may first be detected histochemically in the presumptive muscle cells of the neurula. In order to investigate the 'clock' or counting mechanism that is determining the time when AChE first appears, Whittaker's experiment (1973) has been repeated using eggs of the ascidian, Halocynthia roretzi. Embryos that had been permanently cleavage-arrested with cytochalasin B were able to differentiate AChE in their muscle lineage blastomeres. The time of first AChE occurrence in embryos that had been cleavage-arrested in the 32-cell stage with cytochalasin B was about the same as in normal embryos. This result indicates that the clock is not apparently regulated by the events of cytokinesis. The early gastrulae which had been arrested with colchicine or with colcemid could develop AChE activity, although no histochemically detectable AChE activity was observed in the cleavage-stage embryos that had been arrested with either drug. Therefore the clock does not seem to be controlled by the mitotic cycle of the nucleus. It is suggested that the cycle of DNA replication may be related to the regulation of the clock that is determining the time of development of histospecific protein.

Acetylcholinesterase↗
PubMed1978

A radioimmunoassay of serum 16alpha-hydroxypregnenolone with specific antiserum.

A radioimmunoassay for plasma 16alpha-hydroxypregnenolone has been developed using anti-16alpha-hydroxypregnenolone antiserum produced in rabbits immunized with 16 alpha-hydroxypregnenolone-3-succinate-bovine serum albumin. Radioimmunoassay data were processed and analysed for its validity using a four parameter logistic curve fitting routine with use of the IBM call system. The assay system was satisfactory for a routine use. The 16alpha-hydroxypregnenolone concentrations in the umbilical cord blood at term ranged from 223 to 324 ng/ml. Gas liquid chromatographic analysis revealed a similar result, and also the presence of this steroid in the adrenal gland of the human fetus at midtrimester was confirmed. It is speculated that this steroid is secreted from fetal adrenals.

17-alpha-Hydroxypregnenolone↗
PubMed1978

Cellular morphology and architecture during early morphogenesis of the ascidian egg: an SEM study.

1. Cellular morphology and architecture during early morphogenesis of the ascidian embryo were examined by SEM. 2. The outer surface of the embryo was essentially smooth. The blastocoel could be seen in the dissected blastula. On the cell surface bordering the blastocoel, numerous pseudopodia extended from cells onto adjacent cells. These pseudopodia were suggested to contribute to cell-to-cell adhesion. 3. Before the initiation of gastrulation, a layer of the cells of the animal (ventral) hemisphere and that of the cells of the vegetal (dorsal) hemisphere adhered closely together. The blastocoel could no longer be observed. 4. The gastrulation began during the seventh cleavage. The gastrocoel was formed by a folding of the two layers of the cells. Examinations of the dissected gastrulae suggested two cooperative forces for the gastrulation: first, the epibolic or enfolding movement of the ventral ectoderm cells and secondly, the change in shape of the constituent cells. 5. The neural tube formation progressed in a similar fashion to that of vertebrates.

Animals↗
PubMed1978

Studies on dwarf larvae developed from isolated blastomeres of the starfish. Asterina pectinifera.

Not only a whole denuded egg, but also blastomeres isolated from 2-, 4- and 8-cell starfish embryos developed into morphologically normal, but dwarf bipinnariae, the sizes of which were roughly proportionate to that of the respective original blastomeres. Some of the blastomeres isolated from the 16-cell stage were also capable of developing into the larval stage. All isolated blastomeres divided in good synchrony with the control embryos. Blastulae of all groups gastrulated within quite a short range of time, around 14-5 h after insemination at 20+/-1 degrees C, although one-third of the 1/8-blastula missed this chance but gastrulated by 19.5 h. The number of constituent cells of the 1/8-gastrula was counted to be about 560, which corresponds roughly to one-half that of the 1/4-, one-fourth of the 1/2- and one-eight of the 1/1-gastrula. This ratio also fitted roughly for the total cell volume. The results are compared with those of other invertebrate species, as well as of some vertebrates, and are discussed in connexion not only with the concepts of 'regulative' and 'mosaic' eggs, but also with a criterion that does not fit into either of these; the developmental system of the mammals.

Animals↗
PubMed1977

Sound spectroanalytic diagnosis of malfunctioning prosthetic heart valve.

Sound spectroanalysis was carried out for diagnosis of malfunctioning prosthetic heart valves in 50 cases, which consisted of 31 mitral, 14 aortic, 4 mitral+aortic and 1 tricuspid valve replacements with the age ranging from 17 to 57 years. Types of prosthetic valves used in this series were Starr-Edwards silicon ball valves, metal ball valves, disc valves, Kay-Shiley valves, Smeloff-Cutter valves and a Björk-Shiley valve. The system used in this study consisted of a moving coil microphone, a preamplifier, a filter (160/24 db octave) and a sound spectrograph (Rion Co. S.G. (7). Contour sound spectrograms (SSG) were drawn and peak frequency, wave pattern and frequency-intensity curves were investigated as characteristics of implanted valvular function. Peak frequencies of valvular opening and closing sounds were recorded between 1800 to 5000 Hz and differed according to the types of prosthesis. In mitral+aortic valve replacements, valvular sounds of two prostheses were clearly separated and this finding was very useful for determining the prosthesis which fell into malfunction. Decrease in peak frequency of valvular sounds or abnormal wave patterns in contour SSG were observed in 9 cases (18%). Of 9 cases, 4 cases underwent re-replacement and 2 cases died of congestive heart failure. Operative or autopsy findings gave proof to the findings in sound spectroanalysis.

Adolescent↗
PubMed1977

Fusion of dissociated fish embryonic cells.

The induction of a frequent fusion in dissociated fish embryonic cells is reported. Fusion was induced during mechanical isolation of blastomeres in normal saline solution or Ca2+-free saline solution by quickly bringing about physical contact between cells within about 1-5 min of dissociation. Fused blastomeres were obtained in about 18% yield from early morula cells in about 68% yield from early blastula cells and in about 5% yield from early gastrula cells.

Animals↗