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Y Satou

Publications and source records attributed to Y Satou.

At least 37 records · Page 2Linked to original sources
PubMed2000

Characterization of Brachyury-downstream notochord genes in the Ciona intestinalis embryo.

The notochord has two major roles during chordate embryogenesis, as a source of inductive signals for the patterning of neural tube and paraxial mesoderm and as a supportive organ of the larval tail. Despite the recent identification of mutations that affect the notochord development in vertebrate embryos, little is known about genes that are expressed in the differentiating notochord itself. In the urochordate ascidian Ciona intestinalis, Brachyury (Ci-Bra) plays a key role in notochord differentiation. In a previous study, we isolated cDNA clones for nearly 40 potential Ci-Bra target genes that are expressed in notochord cells (H. Takahashi et al., 1999, Genes Dev. 13, 1519-1523). Here we characterized 20 of them by determining the complete nucleotide sequences of the cDNAs. These genes encode a broad spectrum of divergent proteins associated with notochord formation and function. Two genes encode ascidian homologs of the Drosophila Prickle LIM domain proteins and another encodes the ERM protein, all 3 of which appear to be involved in the control of cytoskeletal architecture. In addition, genes for netrin, leprecan, cdc45, ATP:citrate lyase, ATP sulfurylase/APS kinase, protein tyrosine phosphatase, beta4-galactosyltransferase, fibrinogen-like protein, divergent tropomyosin-like proteins, and Drosophila Pellino-like protein were identified. The observation of the netrin gene expression in the notochord may provide the first molecular evidence that the ascidian notochord is a source of signals as in vertebrates. In addition, the present information should be used to identify nonchordate deuterostome tissues homologous to the notochord as well as genes which are expressed in the notochord cells of vertebrate embryos.

Amino Acid Sequence↗
PubMed2000

Precise measurement of dp elastic scattering at 270 MeV and three-nucleon force effects

The cross section, the deuteron vector A(d)(y) and tensor analyzing powers A(ij), the polarization transfer coefficients K(y('))(ij), and the induced polarization P(y(')) were measured for the dp elastic scattering at 270 MeV. The cross section and A(d)(y) are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, A(ij), K(y('))(ij), or P(y(')) are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models.

Journal Article↗
PubMed2000

Intralobar bronchopulmonary sequestration evaluated by contrast-enhanced three-dimensional MR angiography.

Bronchopulmonary sequestration (PS) is characterized by non-functioning lung tissue fed from one or several aberrant systemic arteries. The condition is diagnosed by visualizing the feeding arteries using non-invasive CT, MRI, colour Doppler sonography or conventional angiography. We present a 5-year-old boy in whom intralobar sequestration was diagnosed using contrast-enhanced 3D MR angiography, which visualised fine blood vessels in the thoraco-abdominal region without arterial puncture. This technique is useful for diagnosing PS.

Bronchopulmonary Sequestration↗
PubMed2000

(beta)-catenin mediates the specification of endoderm cells in ascidian embryos.

In the present study, we addressed the role of (beta)-catenin in the specification of embryonic cells of the ascidians Ciona intestinalis and C. savignyi and obtained the following results: (1) During cleavages, (beta)-catenin accumulated in the nuclei of vegetal blastomeres, suggesting that it plays a role in the specification of endoderm. (2) Mis- and/or overexpression of (beta)-catenin induced the development of an endoderm-specific alkaline phosphatase (AP) in presumptive notochord cells and epidermis cells without affecting differentiation of primary lineage muscle cells. (3) Downregulation of (beta)-catenin induced by the overexpression of cadherin resulted in the suppression of endoderm cell differentiation. This suppression was compensated for by the differentiation of extra epidermis cells. (4) Specification of notochord cells did not take place in the absence of endoderm differentiation. Both the overexpression of (beta)-catenin in presumptive notochord cells and the downregulation of (beta)-catenin in presumptive endoderm cells led to the suppression of Brachyury gene expression, resulting in the failure of notochord specification. These results suggest that the accumulation of (beta)-catenin in the nuclei of endoderm progenitor cells is the first step in the process of ascidian endoderm specification.

Alkaline Phosphatase↗
PubMed1999

posterior end mark 3 (pem-3), an ascidian maternally expressed gene with localized mRNA encodes a protein with Caenorhabditis elegans MEX-3-like KH domains.

Maternal factors localized in the posterior-vegetal cytoplasm of an ascidian egg are essential for cell specification and pattern formation of the embryo. The molecular identification of the localized factors and the elucidation of the machinery associated with the localization are therefore key research subjects. I report here the isolation and characterization of a novel maternally expressed gene, posterior end mark 3 (pem-3). The pem-3 cDNA was obtained from a cDNA library of fertilized egg mRNAs subtracted with gastrula mRNAs of Ciona savignyi. As in the case of pem (Yoshida et al., 1996, Development 122, 2005-2012), the pem-3 maternal transcript was gradually concentrated after fertilization in the posterior-vegetal cytoplasm of the egg, and it later marked the posterior end of developing embryos. The PEM-3 protein was also detected in the posterior end of early embryos. The nucleotide sequence predicted that pem-3 encodes a probable RNA-binding protein with two KH domains that have an extensive similarity with those of Caenorhabditis elegans MEX-3. MEX-3 is also localized in nematode embryos (Draper et al., 1996, Cell 87, 205-216), suggesting that PEM-3 is a candidate homologue of MEX-3. In addition to maternal expression, a zygotic transcript of pem-3 and its gene product were detected in cells of the neural plate, mesenchyme, and epidermis of embryos after the neural-plate stage. Inhibition of zygotic expression using an antisense oligonucleotide resulted in the development of abnormal larvae without sensory pigment cells, suggesting that the zygotic PEM-3 plays a role in the differentiation of the brain of the ascidian larva.

Amino Acid Sequence↗
PubMed1999

Expression cloning of an ascidian syndecan suggests its role in embryonic cell adhesion and morphogenesis.

Expression cloning of maternally expressed genes of the ascidian Ciona savignyi demonstrated that the overexpression of syndecan, a member of a multigene family of integral membrane heparan sulfate proteoglycans, resulted in a disturbance of cell adhesion and morphogenesis. The Ciona syndecan gene was expressed both maternally and zygotically. The maternal transcript was distributed evenly in fertilized eggs and early embryos up to the 32-cell stage without any special localization and then became barely detectable in the 64-cell and gastrula stages. The zygotic transcription became evident during neurulation, mainly in cells of epidermis, the central nervous system, and mesenchyme. Embryos with syndecan overexpression via RNA injection cleaved as did normal embryos, but showed loose blastomere adhesion after the 32-cell stage. Gastrulation occurred, but the closure of the blastopore was markedly delayed, resulting in larvae without normal morphology. About half of the syndecan-overexpressing embryos hatched, and differentiation of epidermis, endoderm, muscle, and notochord was evident. However, the formation of pigment cells of the sensory organs was markedly disturbed. These results indicate that an appropriate level of syndecan expression is required for normal cell adhesion and morphogenesis of the ascidian embryo.

Amino Acid Sequence↗
PubMed1999

Developmental gene activities in ascidian embryos.

The fertilized egg of ascidians develops quickly into a tadpole-type larva consisting of several distinct types of tissues including epidermis, central nervous system, endoderm, mesenchyme, notochord, and muscle. This architecture of the ascidian larva represents the most simplified chordate body plan. Taking advantage of simple, well-defined cell lineages, the expression of developmental genes is analyzed at single-cell level. Advances in the methodology promote the ascidian embryo as a useful system for studying transcriptional control involved in the specification of embryonic cells and pattern formation of the embryo.

Animals↗
PubMed1999

Identification and characterization of maternally expressed genes with mRNAs that are segregated with the endoplasm of early ascidian embryos.

Endoderm cells of the ascidian embryo are specified autonomously dependent on maternal cytoplasmic information or determinants that are localized in the endoplasm. In the present study, we identified three maternally expressed genes (CsEndo-1, CsEndo-2 and CsEndo-3) by screening a cDNA library of Ciona savignyi fertilized egg mRNAs subtracted with gastrula mRNAs. CsEndo-1 encoded a protein with nuclear localization signals, CsEndo-3 predicted a protein containing both a potential transmembrane domain and the PDZ domain, and CsEndo-2 suggested a protein with no similarity to known proteins. The maternal transcripts of all of these genes were not concentrated during early stages of embryogenesis up to the 8-cell stage, but were concentrated at the endoplasmic region by the 16-cell stage and then segregated later with the endoplasm. At the 110-cell stage, the maternal transcript of CsEndo-1 was evident only in the primordial endoderm cells, while those of CsEndo-2 and CsEndo-3 were found in the primordial endoderm cells as well as the primordial notochord cells. All of the transcripts became barely detectable during gastrulation and neurulation. Later, zygotic expression of the three genes became evident again in the endoderm and notochord cells, suggesting developmental roles in the formation of these types of cell. Although we were not able to deduce their functions, this is the first report of maternal genes with mRNAs that are segregated with the endoplasm of ascidian embryos.

Amino Acid Sequence↗
PubMed1998

Four acylated triterpenoid saponins from Albizia procera.

Four new oleanane-type triterpene glycosides, proceraosides A-D (1-4), were isolated from the seeds of Albizia procera. Their structures were established by extensive NMR experiments and chemical methods. Compounds 1-3 comprised acacic acid as the aglycon and a monoterpenic carboxylic acid linked to a monoterpene quinovoside as the acyl moiety at C-21. The common oligosaccharide moiety linked to C-28 in 1-3 was determined as alpha-l-arabino- furanosyl-(1-->4)-[beta-D-glucopyranosyl-(1-->3)]-alpha-L-rhamnopyranosy l- (1-->2)-beta-D-glucopyranosyl ester. These compounds differed in the C-3-linked sugar unit or in the configuration of C-6' of the inner monoterpene moiety in the C-21-linked acyl unit. Compound 4 was established as the 16-deoxy analogue of 1.

Carbohydrate Sequence↗
PubMed1998

[Hyperbaric oxygenation therapy in idiopathic sudden sensory neural hearing loss].

We analyzed statistically the prognosis of hearing impairment in patients with idiopathic sudden sensory neural hearing loss. 119 patients (HBO group) were treated with a combination of hyperbaric oxygenation (HBO) and stellate ganglion block (SGB), as well as oral administration of vasodilator and vitamins. Another 107 patients (control group) were treated with various other therapies. Collectively, the therapeutic outcome in the HBO group was better than in the control group. In addition, the recovery rate of hearing in the HBO group was superior to that in the control group for those cases which had severe hearing loss at the first medical examination, had been seen more than two weeks after onset, and had resisted other treatments. As a result of this study, we conclude that HBO is an effective therapeutic tool.

Acute Disease↗
PubMed1998

[A case of pulmonary infection with mycobacterium xenopi].

A 42-year-old man with pulmonary disease caused by Mcobacterium xenopi is described. He had a history of alcohol use of over 20 years. He was admitted to another hospital for evaluation of an abnormal chest shadow. A chest X-ray showed a cavitary shadow with infiltration in the right upper lung field. Acid-fast organisms were recognized in sputum and M. xenopi was identified by DNA-DNA hybridization. Although he had been treated with isoniazid, rifampicin, and ethanbutol for 5 years, sputum remained positive on culture and chest X-ray findings did not improve. He was later admitted to our hospital for surgery, and right upper lobectomy was performed. He has remained well for 18 months since the operation. In Japan, cases of the pulmonary infection with M. xenopi are rare. Surgical resection is required when chemotherapy is unsuccessful.

Adult↗
PubMed1997

Posterior end mark 2 (pem-2), pem-4, pem-5, and pem-6: maternal genes with localized mRNA in the ascidian embryo.

The posterior-vegetal cytoplasm of an ascidian egg contains maternal factors required for pattern formation and cell specification of the embryo. We report here the isolation and characterization of cDNA clones for novel maternal genes, posterior end mark 2 (pem-2), pem-4, pem-5, and pem-6. We obtained these clones from a cDNA library of Ciona savignyi fertilized egg mRNAs subtracted with gastrula mRNAs by examining the localization of the corresponding mRNAs of randomly selected clones by whole-mount in situ hybridization. As in the case of pem, all of these mRNAs were localized in the posterior-vegetal cytoplasm of the egg, and they later marked the posterior end of early embryos. The predicted amino acid sequence suggested that PEM-2 contains a signal for nuclear localization, an src homology 3 (SH3) domain, and a consensus sequence of the CDC24 family guanine nucleotide dissociation stimulators (GDSs). PEM-4 has a signal for nuclear localization and three C2H2-type zinc finger motifs, while PEM-5 and PEM-6 show no similarity to known proteins. These results provide further evidence that the ascidian egg contains maternal messages that are localized in the posterior-vegetal cytoplasm.

Amino Acid Sequence↗
PubMed1996

An intrinsic genetic program for autonomous differentiation of muscle cells in the ascidian embryo.

The B-line presumptive muscle cells of ascidian embryos have extensive potential for self-differentiation dependent on determinants prelocalized in the myoplasm of fertilized eggs. Ascidian larval muscle cells therefore provide an experimental system with which to explore an intrinsic genetic program for autonomous specification of embryonic cells. Experiments with egg fragments suggested that maternal mRNAs are one of the components of muscle determinants. Expression of larval muscle actin genes begins as early as the 32-cell stage, prior to the developmental fate restriction of the cells. The timing of initiation of the actin gene expression proceeds the expression of an ascidian homologue of vertebrate MyoD by a few hours. Mutations in the proximal E-box of the 5' flanking region of the actin genes did not alter the promoter activity for muscle-specific expression of reporter gene. These results, together with results of deletion constructs of fusion genes, suggest that muscle determinants regulate directly, or indirectly via regulatory factors other than MyoD, the transcription of muscle-specific structural genes leading to the terminal differentiation.

Actins↗
PubMed1995

[Long term remission following relapsed CNS lymphoma].

A case of NHL which has been in long-term remission following vigorous treatment for CNS relapse with intrathecal administration of Ara-C and focal irradiation to the brain is presented. The patient was a 61-year-old man, who was successfully treated with CHOP followed by MACOP-B for diffuse large cell NHL in 1988. Five months later he was admitted to our hospital because of loss of visual acquity and numbness in the right upper and lower extremities. The presence of lymphoma cells in CSF, abnormal shadow in the left frontal lobe on a cranial CT scan and MRI scan, and positive Ga scintigraphy yielded a diagnosis of CNS relapse of NHL. Twenty one whole brain and additional 1.0Gy to the left frontal lobe of irradiation were performed. Eight days later the left tumor disappeared. Neurological remission was obtained and has continued until now.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

[Comparison between the mammographic extent of microcalcifications and the virtual extent of breast carcinoma, and observation of changes in mammographic features with time].

In 26 nonpalpable breast carcinoma cases showing microcalcifications not accompanied by any associated mass on mammograms, the maximum diameter of the area of microcalcifications was measured and then compared with the histological extent of carcinoma. The extent of carcinoma was larger than the diameter of the area of microcalcifications in 14 cases (53.8%) and almost equal in five cases. When the maximum diameter of the area of microcalcifications was less than 2.5cm, carcinoma extended no more than 1.5cm beyond the diameter of the microcalcifications. Employing 24 cases subjected to excision biopsy, the extent of carcinoma was compared with the diameter of the area of microcalcifications on sectioned material containing microcalcifications, and it was found that carcinoma tended to extend further than the extent of calcifications (62.5%). Mammographic microcalcifications obtained from 37 breast cancer cases not accompanied by any associated mass were analyzed in contrast to their previous survey films. Twelve cases were found to have shown several extremely faint calcifications on the previous survey films. Follow-up study that focused on such faint calcifications had been performed in 43 cases from 1990 to 1992, resulting in the successful detection of four cases of breast cancer.

Adult↗