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Yuki Sato

Publications and source records attributed to Yuki Sato.

60 records · Page 4Linked to original sources
PubMed2002

Pax 2 expression in mesodermal segmentation and its relationship with EphA4 and Lunatic-fringe during chicken somitogenesis.

In the Pax gene family, which encodes DNA-binding proteins, Pax 2 has been known to play important roles in the formation of the midbrain/hindbrain boundary, eye, inner ear and kidney in vertebrates (Bioessays 19 (1997) 755). In this article, we report a segmentally regulated pattern of Pax 2 expression during chicken somitogenesis. Pax 2 mRNA is localized in the rostral end of the unsegmented presomitic mesoderm (PSM), abutting anteriorly on a prospective segmentation border. This pattern repeats every segmentation cycle (90 min) observed in ovo and also in the half embryo culture assay in which one half of PSM along the midline is fixed immediately while the other half is cultured for a given period. We also determined the sequence of changes in Pax 2 expression during a segmentation cycle by comparing the pattern of Pax 2 with that of Lunatic-fringe (L-fringe), known to cycle periodically in posterior PSM. A systematic comparison of the expression patterns between Pax 2, L-fringe and EphA4 further highlighted a close relationship between EphA4 and Pax 2 during a segmentation cycle. Lastly, Pax 2 is not segmentally expressed in mouse PSM, suggestive of species (avian)-specific mechanisms underlying somitic segmentation.

Animals↗
PubMed2002

Morphological boundary forms by a novel inductive event mediated by Lunatic fringe and Notch during somitic segmentation.

Boundary formation plays a central role in differentiating the flanking regions that give rise to discrete tissues and organs during early development. We have studied mechanisms by which a morphological boundary and tissue separation are regulated by examining chicken somite segmentation as a model system. By transplanting a small group of cells taken from a presumptive border into a non-segmentation site, we have found a novel inductive event where posteriorly juxtaposed cells to the next-forming border instruct the anterior cells to become separated and epithelialized. We have further studied the molecular mechanisms underlying these interactions by focusing on Lunatic fringe, a modulator of Notch signaling, which is expressed in the region of the presumptive boundary. By combining DNA in ovo electroporation and embryonic transplantation techniques we have ectopically made a sharp boundary of Lunatic fringe activity in the unsegmented paraxial mesoderm and observed a fissure formed at the interface. In addition, a constitutive active form of Notch mimics this instructive phenomenon. These suggest that the boundary-forming signals emanating from the posterior border cells are mediated by Notch, the action of which is confined to the border region by Lunatic fringe within the area where mRNAs of Notch and its ligand are broadly expressed in the presomitic mesoderm.

Animals↗
PubMed2002

[One-lung anesthesia was successfully maintained by means of Fogarty Catheter in infants].

We experienced one-lung anesthesia using Fogarty catheter as a selective bronchial blocker in two infants. First case was a one-year and ten month-old female who underwent partial resection of the right middle lobe for her giant lung cyst under general anesthesia. Second case was an eight-month-old male who underwent thoracoscopic resection of his left mediastinal tumor under general anesthesia. One-lung anesthesia was successfully established with Fogarty catheters for both cases. Size of the catheter and its balloon was decided beforehand by measuring the diameter and length of the trachea and both bronchi based on the image obtained from computerized tomography (CT) in both cases. Therefore, surgical field was well visible during operation. There was no accidental episode in perioperative period. Bronchoscopy with ultra-thin fiberscope and X-ray fluoroscopy is useful to decide the position of Fogarty catheter and its balloon. Our means is recommendable for maintenance of one-lung anesthesia in infant.

Anesthesia, General↗
PubMed2002

[Antibacterial activity of panipenem against clinical isolates in 2000 and 2001].

As the post-marketing surveillance of panipenem/betamipron (Carbenin), MICs of panipenem (PAPM) against 1355 clinical isolates of 28 species from 15 medical institutions all over Japan from June 2000 to March 2001 were measured using the broth microdilution method approved by the Japanese Society of Chemotherapy and compared with those of parenteral carbapenem antibacterials, imipenem (IPM) and meropenem (MEPM), and parenteral cephem antibacterials, cefozopran, cefepime, and sulbactam/cefoperazone. The activity of PAPM was comparable to that of IPM against almost all species tested. Compared with MEPM, PAPM was more active against Gram-positive bacteria and Bacteroides spp., and less active against Gram-negative bacteria. Compared with the parenteral cephems, PAPM was more active against most of species tested and its MIC ranges were narrower than those of the cephems as were those of other carbapenems. In this surveillance study, the incidence of resistance in various species were as follows: 39.3% for methicillin-resistant Staphylococcus aureus, 47.3% for penicillin-intermediate Streptococcus pneumoniae (PISP), 15.1% for penicillin-resistant S. pneumoniae (PRSP), 0.9% for extended-spectrum beta-lactamase (ESBL) producing Escherichia coli, 3.4% for ESBL producing Klebsiella pneumoniae, 19.2% for beta-lactamase producing Haemophilus influenzae, 24.0% for beta-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae, and 1.0% for metallo-beta-lactamase producing Pseudomonas aeruginosa. Against these resistant strains, carbapenems including PAPM showed generally more potent activity than cephems. It was noted that PAPM showed the most potent activity against PISP and PRSP, which showed high incidence of 62.4% totally, among tested drugs. Metallo-beta-lactamase producing P. aeruginosa exhibited high resistance and BLNAR H. influenzae also exhibited low susceptibility against all tested drugs. But no remarkable change in the activity of PAPM against other species was observed in this study compared with that in the studies before the marketing of Carbenin. Furthermore, it is necessary to pay much attention to the trend of resistant strains such as PRSP, metallo-beta-lactamase producing bacteria, and BLNAR H. influenzae.

Adolescent↗
PubMed2002

[Antibacterial activity of cefpodoxime against clinical isolates in 2000 and 2001].

As the post-marketing surveillance of cefpodoxime proxetil (Banan), MICs of cefpodoxime (CPDX, an active form of Banan) against 1090 clinical isolates of 22 species from 15 medical institutions all over Japan from June 2000 to March 2001 were measured using the broth microdilution method approved by the Japanese Society of Chemotherapy and compared with those of oral cephem antibacterials, cefaclor, cefdinir, cefditoren, and cefcapene. In this study, remarkable change in the activity of CPDX was observed in Streptococcus pneumoniae and Haemophilus influenzae compared with the susceptibility in the studies before Banan was launched. This cause is considered to be the increase in the incidence of the following resistant strains: penicillin-intermediate S. pneumoniae (47.3%), penicillin-resistant S. pneumoniae (PRSP, 15.1%), and beta-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae (24.0%), which were scarcely isolated in 1989 when Banan was launched. Other tested drugs also exhibited low activity against these resistant strains. However, CPDX showed comparatively good activity with MIC90 of 2 micrograms/mL against PRSP. Against methicillin-susceptible Staphylococcus spp., Streptococcus pyogenes, Streptococcus agalactiae, and Moraxella catarrhalis, CPDX also showed comparatively good activity with MIC90 of < or = 4 micrograms/mL, which was almost equal to that in the studies before its marketing. Against quinolones-resistant Neisseria gonorrhoeae, CPDX showed excellent activity with MIC90 of 0.5 microgram/mL. Against members of the family Enterobacteriaceae except for Citrobacter freundii, Enterobacter spp., Proteus vulgaris, and Morganella morganii, CPDX showed good activity. However, in Escherichia coli, Klebsiella spp. Proteus spp., and Providencia spp., there are some high-resistant strains to all tested drugs including CPDX. Against Peptostreptococcus spp., MIC90 of CPDX was 8 micrograms/mL and its MIC range was widely distributed from 0.03 to 32 micrograms/mL, which were similar to those in the studies before its marketing. In this study, CPDX showed the decrease in the activity against several species as did other drugs tested, but against most of species tested, CPDX maintained good activity. Furthermore, it is necessary to pay much attention to the trend of resistant strains.

Adolescent↗