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Biomedical subjects

N Satoh

Publications and source records attributed to N Satoh.

At least 109 records · Page 6Linked to original sources
PubMed1999

Genomic organization and the 5' upstream sequences associated with the specific spatio-temporal expression of HrEpiC, an epidermis-specific gene of the ascidian Halocynthia roretzi.

An epidermis-specific gene HrEpiC of the ascidian Halocynthia roretzi is activated in all presumptive blastomeres by the 64-cell stage. To explore the molecular mechanisms underlying the regulation of the timing of activation of HrEpiC, we studied the genomic organization and the 5' upstream sequences of HrEpiC associated with specific spatio-temporal expression of the gene. The restriction site mapping and sequencing of genomic clones showed that the H. roretzi genome contained two copies of HrEpiC gene, HrEpiC1 and HrEpiC2, aligned tandemly in about 8 kb of the genome. Analysis of various deletion constructs with the 5' flanking sequences of HrEpiC1 revealed that 103 bp of the 5' flanking region was sufficient for the minimal epidermis-specific expression of HrEpiC1 and that the region between -281 bp and -198 bp of the 5' flanking region was associated with the amplification of the minimal expression of the reporter gene in the epidermis. This module between -281 bp and -198 bp was also shown to be associated with the timing of the activation of HrEpiC1 by the 64-cell stage. We discussed how the spatio-temporal expression pattern of HrEpiC1 is regulated by the two modules.

Amino Acid Sequence↗
PubMed1999

[A case of tracheoesophageal fistula cured by surgical therapy after blunt trauma received 38 years ago].

We experienced a case of tracheoesophageal fistula successfully cured by surgical therapy after blunt trauma received 38 years ago. A 71-year-old man was injured blunt trauma at right chest by traffic accident in 1960, and was treated for pneumothorax and ribs fracture. In April, 1998, the patient came to the hospital for hemoptysis. Tracheoesophageal fistula at membranous wall 3 cm upper from the carina was diagnosed and operation was performed. Severe adhesion at 3 cm upper from carina was thought to be fistula. Incision was made at lateral esophageal wall and the fistula was confirmed at the esophageal anterior wall and the esophagus was cut in a circle around the fistula. Trachea was closed 1 layer sutures using esophageal all layers and esophagus was closed with 2 layer sutures. A pedicled 4th intercostal muscle was interposed between the tracheal and esophageal suture lines. Prevention of tracheal stenosis was possible without resection of fistula and closure of trachea using esophageal all layers. This operation was seemed to be effective. This case is supposed to be the longest delay between time of injury and its repair in the world.

Accidents, Traffic↗
PubMed1998

Regulation of the trunk-tail patterning in the ascidian embryo: a possible interaction of cascades between lithium/beta-catenin and localized maternal factor pem.

Embryonic cell specification and pattern formation in the ascidian embryo are controlled by prelocalized egg cytoplasmic determinants. In previous studies, we showed that overexpression of a maternal gene, posterior end mark (pem), whose transcript localizes to posterior-vegetal cytoplasm of the fertilized egg, causes a loss of the anterior and dorsal structures of the larva (Yoshida et al., Development 122, 2005-2012, 1996). In the present study, first we observed that lithium treatment resulted in reduction of the larval tail. Lineage tracing analyses revealed that descendants of the A4.1 blastomere of the 8-cell-stage embryo (which forms the greater part of notochord and nerve cord) were missing from the tail region, that they were translocated anteriorly into the trunk region, and that the fate of the A4.1-line notochord cells had changed to endoderm. These results suggest that lithium treatment affects the trunk-tail patterning during embryogenesis by changing the cell fate of specific cell lineages. Second, we showed that lithium treatment could rescue the anterior and dorsal structures in pem-overexpressed larvae. This result suggests that pem plays a role in the patterning of the ascidian embryo via a signaling cascade that is affected by lithium. Third, we isolated an ascidian beta-catenin gene and found that overexpression of beta-catenin in the A4.1 blastomere had effects very similar to lithium treatment, such as reduction of the tail and anterior translocation of A4.1 descendants. These results suggest that the target of lithium is, at least in part, the Wnt-signaling cascade and that pem may also function via this cascade.

Amino Acid Sequence↗
PubMed1998

Conservation of the developmental role of Brachyury in notochord formation in a urochordate, the ascidian Balocynthia roretzi.

The notochord is one of the characteristic features of the phylum Chordata. The vertebrate Brachyury gene is known to be essential for the terminal differentiation of chordamesoderm into notochord. In the ascidian, which belongs to the subphylum Urochordata, differentiation of notochord cells is induced at the late phase of the 32-cell stage through cellular interaction with adjacent endoderm cells as well as neighboring notochord cells. The ascidian Brachyury gene (As-T) is expressed exclusively in the notochord-lineage blastomeres, and the timing of gene expression at the 64-cell stage precisely coincides with that of the developmental fate restriction of the blastomeres. In addition, experimental studies have demonstrated a close relationship between the inductive events and As-T expression. In the present study, we show that overexpression of As-T by microinjection of the synthesized As-T RNA results in the occurrence, without the induction, of notochord-specific features in the A-line presumptive notochord blastomeres. We also show that overexpression of As-T RNA leads to ectopic expression of notochord-specific features in non-notochord lineages, including those of spinal cord and endoderm. These results strongly suggest that the developmental role of the Brachyury is conserved throughout chordates in notochord formation.

Animals↗
PubMed1998

Satiety effect and sympathetic activation of leptin are mediated by hypothalamic melanocortin system.

Leptin is an adipocyte-derived blood-borne satiety factor that decreases food intake and increases energy expenditure, thereby leading to a substantial decrease in body weight. To explore the possible roles of the hypothalamic melanocortin system in leptin action, we examined the effects of intracerebroventricular (i.c.v.) injection of leptin with or without SHU9119, a potent antagonist of alpha-melanocyte stimulating hormone, on food intake, body weight, and mitochondrial uncoupling protein-1 (UCP-1) mRNA expression in the brown adipose tissue (BAT) in rats. A single i.c.v. injection of leptin decreased cumulative food intake and body weight gain, and increased UCP-1 mRNA expression during 3 h at the onset of the dark phase. Inhibition of food intake and body weight change with leptin was reversed by co-injection of SHU9119 in a dose-dependent manner. Co-injection of SHU9119 also inhibited completely the leptin-induced increase in UCP-1 mRNA expression in the BAT. Treatment with SHU9119 alone did not affect food intake, body weight, and UCP-1 mRNA expression in rats. The present study provides evidence that the hypothalamic melanocortin system plays a central role in both satiety effect and sympathetic activation of leptin.

Adipose Tissue, Brown↗
PubMed1998

Quantity of prelocalized maternal factor is associated with the timing of initiation of an epidermis-specific gene expression of the ascidian embryo.

We produced half-egg-volume ascidian embryos by dividing the unfertilized egg of Halocynthia roretzi at the equatorial plane, and investigated the timing of the initiation of the expression of three tissue-specific genes, a muscle-specific actin gene HrMA4, a notochord-specific gene As-T and an epidermis-specific gene HrEpiC in the half-egg-volume embryos of the animal side and those of the vegetal side. The timing of the onset of HrMA4 and As-T expression in both the animal- and vegetal-half embryos and that of HrEpiC expression in the animal-half embryos were essentially the same as that of normal embryos. In contrast, the timing of HrEpiC expression in the vegetal-half embryos was delayed by one division cycle compared with the normal embryos. This delay was partially recovered by increasing the amount of unfertilized egg cytoplasm of the animal hemisphere, suggesting that the timing of HrEpiC expression is regulated by the amount of a maternal factor which is distributed abundantly in the animal hemisphere of the unfertilized egg.

Actins↗
PubMed1998

Expression of an ascidian gene in the tip of the tail of tail-bud-stage embryos.

The occurrence of tadpole-type larvae is one of the key events used to understand the origin and evolution of chordates, and the tail bud of chordate embryos is thought to be associated with formation of the tip of the tail. Although some transcriptional factor genes including Brachyury are expressed in the tail bud, no structural genes have been reported to be expressed there. We report here that an ascidian gene HrTT-1 is expressed exclusively in the tip of elongating tail of the tail-bud embryo. This gene encodes a possible secreted protein of 415 amino acids with the SCP/TPX family consensus sequences.

Amino Acid Sequence↗
PubMed1998

Early changes in excitation-contraction coupling: transition from compensated hypertrophy to failure in Dahl salt-sensitive rat myocytes.

OBJECTIVE: The aims were to (1) define the early changes in excitation-contraction coupling during the transition from cardiac hypertrophy to heart failure, and (2) to clarify the causal relationship between mechanical dysfunction and abnormal Ca2+ handling in the Dahl salt-sensitive rat model. METHODS: Myocardial contractile function was assessed in whole heart perfusion studies. In separate experiments, isolated left ventricular myocytes from Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats were paced at a physiological rate of 5Hz and cell shortening (CS) and [Ca2+]i measured simulataneously by video-edge detection and fura-2 fluorescence. RESULTS: DS hearts developed hypertrophy after 4 weeks of a high-salt diet (4WHSD), as indicated by a 26% increase (p < 0.01) in the heart to body weight ratio and a 21% increase (p < 0.01) in cell width. Heart failure developed after 12 weeks of a high-salt diet (12WHSD), as indicated by an 11% increase (p < 0.01) in the lung wet to dry weight ratio. Furthermore, in DS-12WHSD hearts, the diastolic pressure-volume relationship had shifted rightward. DR rats did not develop hypertension and seved as age-matched controls. A 31% (p < 0.05) increase in the %CS in DS-4WHSD myocytes compared to DR-4WHSD myocytes with a trend of a parallel increase in Ca2+ transient amplitude was found. There was no difference in the Ca2+ transient parameters between DR and DS at 12WHSD, but an 18% (p < 0.01) decrease occurred in peak [Ca2+]i in DS myocytes between 4WHSD and 12WHSD. In DS-12WHSD, the time to peak shortening and the time from peak shortening to 50% and 90% relaxation was significantly prolonged by 27%, 44%, and 38%, respectively, as compared to the age-matched DR myocytes. CONCLUSION: Our results indicated that: (I) normal Ca2+ homeostasis is preserved at the stage of compensated hypertrophy; (2) the early signs of isolated myocyte dysfunction were a prolongation of the shortening and relaxation time course without an abnormal time course of the Ca2+ transient. Thus, in the hypertensive Dahl salt rat model, abnormal Ca2+ handling appears neither to precede nor initiate the transition to failure.

Animals↗
PubMed1998

The significance of the Trp 64 Arg mutation of the beta3-adrenergic receptor gene in impaired glucose tolerance, non-insulin-dependent diabetes mellitus, and insulin resistance in Japanese subjects.

It has been reported that the Trp 64 Arg mutation of the human beta3-adrenergic receptor (beta3-AR) gene is related to an earlier age of onset of non-insulin-dependent diabetes mellitus (NIDDM) and features of insulin resistance and weight gain in morbidly obese patients. However, such findings have not been consistent in varying ethnic populations. In the present study, we investigated the frequency of the Trp 64 Arg mutation of the human beta3-AR gene in Japanese control subjects (n = 253) and in NIDDM (n = 314) and impaired glucose tolerance (IGT) patients (n = 100). We compared the frequency of the mutation with the body-mass index (BMI) in these groups and with the metabolic clearance rate (MCR) of glucose in the NIDDM patients. A Trp 64 Arg mutation was observed in 36.7%, 31.6%, and 37.0% of the control, NIDDM, and IGT subjects, respectively. The frequency of the homozygotes for the mutation was 4.3%, 4.8%, and 3.0%, respectively. Neither the genotype frequency (Trp/Arg, Arg/Arg) nor the frequency of the mutated allele was significantly different among the three groups. The BMI of the subjects with the mutation was not significantly higher than that of the subjects without the mutation in each group. Furthermore, the allele frequency (A) was not different among the subjects with different BMIs (BMI < 22.0, 22.0 < or = BMI < or = 26.4, BMI > 26.4) in each group. In a separate group of NIDDM patients, the MCR of the subjects with intermediate BMIs (22.0 < or = BMI < or = 26.4) with the mutation tended to be lower than that of those without the mutation. In addition, the MCR of the subjects with the mutation in this group was significantly lower compared with that of those with a BMI less than 22. These results indicate that the Trp 64 Arg mutation of the beta3-AR gene may not contribute to the development of NIDDM or be a determinant of obesity in the Japanese population. However, the mutation may contribute to insulin resistance in NIDDM patients with an intermediate BMI.

Adult↗
PubMed1998

Novel pattern of Brachyury gene expression in hemichordate embryos.

Together with echinoderms and chordates, hemichordates constitute the third major group of the deuterostomes, which share a number of common developmental features. The Brachyury gene is responsible for the formation of notochord, the most defining feature of chordates. Therefore, isolation and characterization of the hemichordate homolog of Brachyury is key to understand the origin and evolution of chordates. Here we show that the hemichordate Brachyury gene (PfBra) is expressed in two regions of the gastrula and young tornaria larva, the archenteron invagination region and the stomodeum invagination region.

Amino Acid Sequence↗
PubMed1998

An ascidian gene encoding an SH2-domain protein is expressed in the notochord cells of the embryo.

Differentiation of notochord cells in the ascidian embryo requires cell-cell interactions and signal transduction pathways. Isolation and characterization of an ascidian gene (HrSH2) from Halocynthia roretzi is reported. Sequence analysis suggests that HrSH2 encodes a polypeptide with an SH2 domain and a tyrosine kinase phosphorylation site, that are implicated in signaling pathways through tyrosine phosphorylation. Zygotic expression of HrSH2 was transient. The gene expression began at the 110-cell stage but was downregulated by the larval stage. Whole-mount in situ hybridization, taking advantage of well-known lineage, revealed that the HrSH2 transcript first appeared in primordial notochord cells as well as a few endoderm cells of the 110-cell embryo. During gastrulation and neurulation, expression in the endoderm was downregulated, and instead HrSH2 transcript became evident in notochord cells, nerve cord cells, endodermal strand cells and epidermal cells of the tail. These results suggest the possibility that HrSH2 is involved in the signal transduction pathways required for notochord formation and for differentiation of other cells in conjunction with the notochord.

Amino Acid Sequence↗
PubMed1998

Recurrent varicella-zoster virus retinitis in a patient treated with systemic corticosteroids.

A case of recurrent unilateral varicella-zoster virus (VZV) retinitis is reported. The retinitis was characterized by arteriolitis and retinal necrosis with secondary chorioretinal atrophy localized in the periphery of the supratemporal quadrant of the retina. Polymerase chain reaction analysis of aqueous humor demonstrated VZV DNA in both the initial and recurrent episode. The Goldmann-Witmer coefficient for VZV IgG was elevated. The initial VZV retinitis was successfully treated with acyclovir and corticosteroids. Three years later, high-dose corticosteroids alone were used to treat idiopathic facial nerve palsy. One month after concluding corticosteroids therapy, the VZV retinitis recurred in the same eye, suggesting that administration of the high-dose corticosteroids caused VZV reactivation and induced recurrence of VZV retinitis.

Acyclovir↗
PubMed1998

The mitochondrial genome of the hemichordate Balanoglossus carnosus and the evolution of deuterostome mitochondria.

The complete nucleotide sequence of the mitochondrial genome of the hemichordate Balanoglossus carnosus (acorn worm) was determined. The arrangement of the genes encoding 13 protein, 22 tRNA, and 2 rRNA genes is essentially the same as in vertebrates, indicating that the vertebrate and hemichordate mitochondrial gene arrangement is close to that of their common ancestor, and, thus, that it has been conserved for more than 600 million years, whereas that of echinoderms has been rearranged extensively. The genetic code of hemichordate mitochondria is similar to that of echinoderms in that ATA encodes isoleucine and AGA serine, whereas the codons AAA and AGG, whose amino acid assignments also differ between echinoderms and vertebrates, are absent from the B. carnosus mitochondrial genome. There are three noncoding regions of length 277, 41, and 32 bp: the larger one is likely to be equivalent to the control region of other deuterostomes, while the two others may contain transcriptional promoters for genes encoded on the minor coding strand. Phylogenetic trees estimated from the inferred protein sequences indicate that hemichordates are a sister group of echinoderms.

Animals↗
PubMed1998

6-Phosphogluconate dehydrogenase is a 45-kDa antigen recognized by S4D5, a monoclonal antibody specific to vanadocytes in the vanadium-rich ascidian Ascidia sydneiensis samea.

We previously prepared a monoclonal antibody, S4D5, specific to vanadocytes, vanadium-containing blood cells, in the vanadium-rich ascidian Ascidia sydneiensis samea. Here, we demonstrate that a 45-kDa antigen recognized by S4D5 is 6-phosphogluconate dehydrogenase (6-PGDH), an enzyme of the pentose phosphate pathway, based on cDNA isolation of RNA samples from blood cells of the ascidian. Western blot analysis confirmed an abundance of 6-PGDH protein in the vanadocytes and localization of 6-PGDH in the soluble extract of the blood cells. Soluble protein exhibited a correspondingly high level of 6-PGDH enzymatic activity. Ascidians are known to selectively accumulate high levels of vanadium in vanadocytes, and the highest recorded concentration of accumulated vanadium is 350 mM, which is 10(7) times the concentration in sea water. Almost all vanadium ions are reduced to the +3 oxidation state via the +4 oxidation state in vanadocytes, indicating that reducing agents must participate in the accumulation. On the other hand, vanadium ions in the +5 oxidation state are reduced to the +4 oxidation state by the presence of NADPH in vitro. Together, these observations suggest that NADPH produced in the pentose phosphate pathway may conjugate the reduction of vanadium from the +5 oxidation state through the +4 oxidation state in vanadocytes of ascidians.

Amino Acid Sequence↗
PubMed1998

A negative component on event related potential recorded in the drowsy state.

Behavior of event related potential (ERP) components in the drowsy state was examined in nine subjects using oddball paradigm. A component with peak latency of 300 msec, N300, was superimposed on ERP in the drowsy state. N300 appeared also in stage 1 of NREM sleep and closely resembled vertex sharp wave evoked by sound stimulation in both scalp distribution and peak latency. It was suggested that N300 recorded in the drowsy state and vertex sharp wave recorded in stage 1 of NREM sleep are generated by the identical synchronizing mechanism in the brain.

Adult↗
PubMed1998

Some sensory stimuli generate spontaneous K-complexes.

The present study was performed in order to determine whether spontaneous K-complex are induced by sensory stimuli. Electroencephalogram (EEG) segments in stage 2 sleep containing an evoked K-complex or spontaneous K-complex were separately averaged with respect to the peak of N300, one of the main components constituting the K-complex. Small negative and positive components were found immediately before the main components of spontaneous K-complex in averaged EEG. These two components were judged to correspond to N100 and P200 induced by the sound stimulus. The present findings suggest that the spontaneous K-complex is not a spontaneous phenomenon but that it is induced by sensory stimuli.

Adult↗
PubMed1998

Tripartite organization of the ancestral chordate brain and the antiquity of placodes: insights from ascidian Pax-2/5/8, Hox and Otx genes.

Ascidians and vertebrates belong to the Phylum Chordata and both have dorsal tubular central nervous systems. The structure of the ascidian neural tube is extremely simple, containing less than 400 cells, among which less than 100 cells are neurons. Recent studies suggest that, despite its simple organization, the mechanisms patterning the ascidian neural tube are similar to those of the more complex vertebrate brain. Identification of homologous regions between vertebrate and ascidian nervous systems, however, remains to be resolved. Here we report the expression of HrPax-258 gene: an ascidian homologue of vertebrate Pax-2, Pax-5 and Pax-8 genes. Molecular phylogenetic analyses indicate that HrPax-258 is descendant from a single precursor gene that gave rise to the three vertebrate genes. The expression pattern of HrPax-258 suggests that this subfamily of Pax genes has conserved roles in regional specification of the brain. Comparison with expression of ascidian Otx (Hroth) and a Hox gene (HrHox1) by double-staining in situ hybridizations indicate that the ascidian brain region can be subdivided into three regions; the anterior region marked by Hroth probably homologous to the vertebrate forebrain and midbrain, the middle region marked by HrPax-258 probably homologous to the vertebrate anterior hindbrain (and maybe also midbrain) and the posterior region marked by Hox genes which is homologous to the vertebrate hindbrain and spinal cord. Later expression of HrPax-258 in atrial primordia implies that basal chordates such as ascidians have already acquired a sensory organ that develops from epidermal thickenings (placodes) and expresses HrPax-258; we suggest it is homologous to the vertebrate ear. Therefore, placodes are not likely to be a newly acquired feature in vertebrates, but may have already been possessed by the earliest chordates.

Amino Acid Sequence↗