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Biomedical subjects

M Takeuchi

Publications and source records attributed to M Takeuchi.

At least 199 records · Page 11Linked to original sources
PubMed1999

[Reliability of disc-diffusion susceptibility testing for arbekacin, vancomycin and teicoplanin against methicillin-resistant Staphylococcus aureus].

We investigated the differences in judgments among four disc-diffusion methods on susceptibility testing of arbekacin (ABK), vancomycin (VCM) and teicoplanin (TEIC) against 37 strains of methicillin-resistant Staphylococcus aureus (MRSA). These results were compared with minimum inhibitory concentrations (MICs) obtained from micro broth-dilution method. A marked difference was noted in the judgment of susceptibility to TEIC in Tri-disc method, that is 2 strains (5.4%) fell into sensitive (+3) 34 strains (91.9%) into moderately sensitive (+2) and 1 strain (2.7%) into moderately resistant (+), while in Sensi-disc method all strains fell into sensitive (S). According to the MICs, no strain of the MRSA tested revealed resistance to ABK, VCM and TEIC. Consequently, these three antimicrobial agents were thought to be effective on MRSA infections. From these results, we concluded that Tri-disc method for glycopeptide against MRSA, especially for TEIC, is not recommendable as a disc-diffusion method in susceptibility testing.

Aminoglycosides↗
PubMed1998

Left ventricular regional systolic motion in patients with right ventricular pressure overload.

Left ventricular regional systolic motion was investigated in patients with right ventricular pressure overload and 10 controls using tagged cine magnetic resonance imaging. The regional shortening fraction was determined in four segments (septal, lateral, inferior, and anterior) on the short-axis image. An asynchrony index, nonhomogeneity of regional shortening, was calculated. Septal shortening in these patients was depressed, and showed an inverse correlation with the right-to-left ventricular peak pressure ratio (r=-0.80, P<0.01). Lateral shortening was greater in the patients than in the controls (P<0.01). The asynchrony index was significantly greater in the patients than in the controls (P<0.01), and correlated with the right-to-left systolic pressure ratio (r=0.64, P=0.02) and the left ventricular end-diastolic pressure (r=0.79, P<0.01). The altered distribution of regional circumferential shortening results in an increased heterogeneity of regional systolic motion. These findings may have important implications for the assessment of ventricular function in patients with right ventricular pressure overload.

Adult↗
PubMed1998

Suppression of Erk activation and in vivo growth in esophageal cancer cells by the dominant negative Ras mutant, N116Y.

Our previous studies demonstrated that introduction of a dominant negative H-ras mutant, N116Y, inhibits the growth of various types of cancer cells in vitro. In this study, we tested the efficacy of N116Y in blocking the growth of esophageal cancer cells using an adenoviral vector. Infection with N116Y adenovirus, (AdCMV-N116Y), in which N116Y expression is driven by the cytomegalovirus promoter, significantly reduced the in vitro growth of all esophageal cancer cell lines studied. Esophageal cancer cells that contained wild-type K-ras and H-ras (TE8, SGF3, SGF7) were more sensitive to AdCMV-N116Y than HEC46 cells that expressed mutant K-ras protein. Most importantly, direct injection of AdCMV-N116Y into TE8- or SGF3-induced tumors in nude mice suppressed their growth significantly. To examine the suppressive mechanism of N116Y, cell cycle profile and the activation of extracellular signal-regulated kinase 2 (Erk2) were examined by flow cytometry and Western blot analysis, respectively. In TE8 cells, progression into S phase was clearly blocked after infection with AdCMV-N116Y. Infection with AdCMV-N116Y did not strongly suppress the activation of Erk2 after EGF stimulation in serum-starved HEC46 cells, whereas it completely suppressed activation in TE8, SGF3 and SGF7 cells. Our observations suggest that N116Y reduces growth of human esophageal cancer cells and suppresses the activation of Erk2; they also indicate that N116Y is a potential candidate gene for human esophageal cancer gene therapy.

Adenoviridae↗
PubMed1998

New alternatively spliced variants of calmodulin-dependent protein kinase II from rabbit liver.

Polymerase chain reaction analysis revealed four alternatively spliced variants of each of the gamma and delta isoforms of calmodulin-dependent protein kinase II (CaM-kinase II) in rabbit liver. Among the four variants of the gamma isoform, two were novel ones, designated as CaM-kinase II gamma-H and gamma-I. The gamma-I variant possessed both of the two deletable exons; D2a and D2b, which had never been found together in any variant. Sequence analysis of the gamma-I indicated that the D2a was upstream of the D2b and that they were contiguous with each other in the gamma-I. Among the four variants of the delta isoform, two were also novel ones, designated as CaM-kinase II delta-11 and delta-12, and the other two were the already-reported ones, delta-2 and delta-6. The delta-11 and delta-12 were identical to the delta-2 and delta-6, respectively, except that three bases (CAG) located at a splicing junction was deleted in the delta-11 and delta-12, suggesting two splicing sites of a single intron. Thus, the diverse splicing patterns may produce many more variants than those so far considered.

Alternative Splicing↗
PubMed1998

BEGAIN (brain-enriched guanylate kinase-associated protein), a novel neuronal PSD-95/SAP90-binding protein.

PSD-95/SAP90 is a synaptic membrane-associated guanylate kinase with three PDZ, one SH3, and one guanylate kinase (GK) domain. PSD-95/SAP90 binds various proteins through the PDZ domains and organizes synaptic junctions. PSD-95/SAP90 also interacts with the postsynaptic density (PSD) fraction-enriched protein, named SAPAP (also called GKAP and DAP), through the GK domain. SAPAP is Triton X-100-insoluble and recruits PSD-95/SAP90 into the Triton X-100-insoluble fraction in the transfected cells, suggesting that SAPAP may fix PSD-95/SAP90 to the PSD. Here we report a novel protein interacting with the GK domain of PSD-95/SAP90, BEGAIN. BEGAIN is specifically expressed in brain and enriched in the PSD fraction. BEGAIN is Triton X-100-soluble in the transfected cells but is recruited to the Triton X-100-insoluble fraction by SAPAP when coexpressed with PSD-95/SAP90. BEGAIN may be a novel PSD component associated with the core complex of PSD-95/SAP90 and SAPAP.

Amino Acid Sequence↗
PubMed1998

Production of human compatible high mannose-type (Man5GlcNAc2) sugar chains in Saccharomyces cerevisiae.

A yeast mutant capable of producing Man5GlcNAc2 human compatible sugar chains on glycoproteins was constructed. An expression vector for alpha-1,2-mannosidase with the "HDEL" endoplasmic reticulum retention/retrieval tag was designed and expressed in Saccharomyces cerevisiae. An in vitro alpha-1,2-mannosidase assay and Western blot analysis showed that it was successfully localized in the endoplasmic reticulum. A triple mutant yeast lacking three glycosyltransferase activities was then transformed with an alpha-1, 2-mannosidase expression vector. The oligosaccharide structures of carboxypeptidase Y as well as cell surface glycoproteins were analyzed, and the recombinant yeast was shown to produce a series of high mannose-type sugar chains including Man5GlcNAc2. This is the first report of a recombinant S. cerevisiae able to produce Man5GlcNAc2-oligosaccharides, the intermediate for hybrid-type and complex-type sugar chains.

Amino Acid Sequence↗
PubMed1998

A novel multiple PDZ domain-containing molecule interacting with N-methyl-D-aspartate receptors and neuronal cell adhesion proteins.

At synaptic junctions, pre- and postsynaptic membranes are connected by cell adhesion and have distinct structures for specialized functions. The presynaptic membranes have a machinery for fast neurotransmitter release, and the postsynaptic membranes have clusters of neurotransmitter receptors. The molecular mechanism of the assembly of synaptic junctions is not yet clear. Pioneering studies identified postsynaptic density (PSD)-95/SAP90 as a prototypic synaptic scaffolding protein to maintain the structure of synaptic junctions. PSD-95/SAP90 belongs to a family of membrane-associated guanylate kinases and binds N-methyl-D-aspartate receptors, potassium channels, and neuroligins through the PDZ domains and GKAP/SAPAP/DAP through the guanylate kinase (GK) domain. We performed here a yeast two-hybrid screening for SAPAP-interacting molecules and identified a novel protein that has an inverse structure of membrane-associated guanylate kinases with an NH2-terminal GK-like domain followed by two WW and five PDZ domains. It binds SAPAP through the GK-like domain and NMDA receptors and neuroligins through the PDZ domains. We named this protein S-SCAM (synaptic scaffolding molecule) because S-SCAM may assemble receptors and cell adhesion proteins at synaptic junctions.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Beta-casomorphin-5 stimulates neurite outgrowth in a mouse neuroblastoma cell line (Neuro-2a).

We studied the effect of beta-casomorphin-5 (mu-acting opioid peptides derived from milk protein beta-casein) on neurite outgrowth of mouse neuroblastoma cell line, Neuro-2a. Beta-casomorphin-5 stimulated neurite outgrowth of Neuro-2a cells in a naloxone-reversible manner. The stimulating effect of beta-casomorphin-5 was observed even at picomolar concentrations. The selective mu-agonist, (D-Ala2, N-Me-Phe4, Gly5-ol)-enkephalin (DAMGO) exhibited the similar stimulating effect only at micromolar concentrations. On the other hand, (D-Pen(2,5))-enkephalin (DPDPE) (a delta-agonist), U-50,488 (a kappa-agonist), and endogenous opioid peptides, such as enkephalins and dynorphin A (1-13), showed no such stimulating effect. These results suggest that the neurite outgrowth-stimulating action of beta-casomorphin-5 may be mediated via a receptor which has mu-like characteristics and high sensitivity to beta-casomorphin-5, and that beta-casomorphins may play a role as a neurite elongation factor during the suckling period.

Animals↗
PubMed1998

Regional ventricular systolic abnormalities caused by a rudimentary chamber in patients with univentricular hearts.

Previous studies have demonstrated that regional wall motion abnormalities are common in univentricular hearts; however, the mechanism of this abnormality and its relation to hemodynamics remain unclear. The aim of this study was to document and analyze the etiology of regional wall motion abnormality and its relation to hemodynamics in univentricular hearts. Sixteen patients (age 11+/-6 years) were examined. A tagged cine magnetic resonance imaging method that superimposes "tags" on myocardium was used to assess regional systolic motion. The tags were traced from end-diastole to end-systole, and the percent regional shortening fraction was calculated as the shortening ratio. The tags were positioned on 6 segments. Normal ranges for wall motion were established from 10 normal volunteers. An asynchrony index was calculated as the SD divided by the mean regional shortening fraction to quantify asynchronous regional motion. Hemodynamic parameters were also obtained by cardiac catheterization. In patients, regional shortening fraction was significantly lower in segments adjacent to the rudimentary chamber compared with normal values in both circumferential and longitudinal directions (p <0.05 and p <0.01, respectively). The asynchrony index was much greater in patients than in controls (62+/-25 vs 27+/-10, p <0.01). The index correlated with rudimentary chamber volume and the rudimentary/main chamber volume ratio (r = 0.58, r = 0.79, respectively). Furthermore, the index correlated with end-diastolic pressure (r = 0.82). The rudimentary chamber may play an important role in causing asynchronous regional motion, and this motion may contribute to ventricular diastolic dysfunction.

Adolescent↗
PubMed1998

Synthesis and NK1 receptor antagonistic activity of (+/-)-1-acyl-3-(3,4- dichlorophenyl)-3-[2-(spiro-substituted piperidin-1'-yl)ethyl]piperidines.

(+/-)-1-Acyl-3-(3,4-dichlorophenyl)-3-[2-(spiro-substituted piperidin-1'-yl)ethyl]piperidines and their quaternary ammonium salts were prepared and evaluated for their NK1 receptor antagonistic activity. Some of these inhibited SP-induced contraction in guinea pig ileum with IC50 values at a level of 10(-9) M and showed potent inhibitory activity against selective NK1 receptor agonist-induced bronchoconstriction in guinea pigs.

Animals↗
PubMed1998

cDNA cloning and expression of bovine UDP-N-acetylglucosamine: alpha1, 3-D-mannoside beta1,4-N-acetylglucosaminyltransferase IV.

UDP-N-acetylglucosamine:alpha1,3-D-mannoside beta1, 4-N-acetylglucosaminyltransferase (GnT-IV) is one of the essential enzymes in the production of tri- and tetra-antennary Asn-linked sugar chains. Recently, we have successfully purified GnT-IV from bovine small intestine. Based on the partial amino acid sequence of the purified bovine GnT-IV enzyme, its cDNA has been cloned from bovine small intestine. The open reading frame is 1,605 base pairs long, and this sequence produced GnT-IV activity on transient expression in COS-7 cells. Although the deduced amino acid sequence does not have any significant homology with other known N-acetylglucosaminyltransferases (GnTs), the hydrophobicity profile showed a typical type II transmembrane protein structure, which is common to many glycosyltransferases. N-terminal amino acid sequencing of the purified GnT-IV revealed that 92 amino acids, including a transmembrane region, were truncated during purification. Of the three potential N-glycosylation sites Asn-458 was actually glycosylated in the purified enzyme, although this N-glycosylation site could be abolished without any reduction in GnT-IV activity. Serial deletions at both the N and C termini proved that the catalytic domain of GnT-IV is located in the central region of the enzyme. The GnT-IV mRNA level correlated with enzymatic activity in the various bovine tissues tested.

Amino Acid Sequence↗
PubMed1998

Trace analysis of tributyltin and triphenyltin compounds in sea water by gas chromatography-negative ion chemical ionization mass spectrometry.

An analytical gas chromatography-mass spectrometry (GC-MS) method using negative ion chemical ionization (NICI) has been investigated for the determination of trace tributyltin (TBT) and triphenyltin (TPhT) compounds in sea water. TBT and TPhT were extracted from samples as chloride under the acidic condition of HCl. Doping of the GC system with a dilute HBr-methanolic solution resulted in direct detection of the chlorides of TBT, TPhT and tripentyltin (TPenT, internal standard). As the result of HBr doping, a sharp peak of the respective organotin bromides appeared: during GC analysis, halogen exchange from the chloride to the bromide occurred. NICI-MS was highly selective and sensitive for the detection of TBT. TPhT and TPenT bromides. In the selected ion monitoring mode of NICI-MS, the minimum detectable amounts defined as the signal equal to three times the standard deviation (3 sigma) of the baseline noise were 20 and 25 pg ml-1 for TBT and TPhT, respectively. These amounts are approximately 250-400 times better than those in electron impact mode. The combination of GC using an apolar capillary column doped with a dilute HBr-methanolic solution and NICI-MS made it possible to determine TBT and TPhT at less than the ng l-1 level in sea water.

Gas Chromatography-Mass Spectrometry↗
PubMed1998

Interleukin-18 activates the IRAK-TRAF6 pathway in mouse EL-4 cells.

The pleiotropic biological activities of interleukin-18 (IL-18) are mediated by IL-18 receptor (IL-18R). When the ligand binds to the IL-18R, IL-18R initiates a signaling cascade that results in the activation of nuclear factor kappa B (NF-kappa B). When mouse EL-4 cells were exposed to IL-18, IL-1 receptor-associated kinase (IRAK) was recruited to IL-18R and was phosphorylated. In addition, tumor necrosis factor receptor-associated factor-6 (TRAF6) was associated with IRAK. Therefore, we concluded that IL-18/IL-18R-mediated signaling may share the IRAK/TRAF6 pathway through NF-kappa B activation with the IL-1/IL-1 receptor system.

Animals↗
PubMed1998

TGF-beta promotes immune deviation by altering accessory signals of antigen-presenting cells.

Macrophages incubated with OVA in the presence of TGF-beta2 induce immune deviation in vivo (impaired delayed hypersensitivity and IgG2a Ab production) when injected into naive, syngeneic mice. OVA-specific TCR transgenic naive T cells (DO11.10 T cells) produce Th1-type cytokines when stimulated in vitro with OVA-pulsed peritoneal exudate cells (PEC), but if PEC are first treated with TGF-beta2 and then pulsed with OVA, the T cells secrete Th2-type cytokines instead. In this study, we investigated the mechanisms that are involved in the modified Ag-presenting functions of macrophages by TGF-beta2 pretreatment. We have found that: 1) TGF-beta2 impaired the capacity of PEC to produce IL-12 and to express CD40; 2) reduced CD40 expression on TGF-beta2-treated PEC impaired IL-12 production when the cells were cocultured with DO11.10 T cells; 3) the failure of TGF-beta2-treated PEC to stimulate DO11.10 T cells to secrete IFN-gamma was due to their impaired IL-12 production. From these results, we conclude that TGF-beta2 treatment impairs the ability of macrophages to produce IL-12 and to express CD40. As a consequence, TGF-beta2-treated PEC fail to promote development of pT cells toward the Th1 phenotype.

Animals↗
PubMed1998

Molecular cloning and characterization of rat lin-10.

In Caenorhabditis elegans, the vulval induction is mediated by tyrosine kinase receptor/Ras signal transduction pathway composed of the lin-3, let-23, and let-60 products. In addition to these gene products, the lin-2, lin-7, and lin-10 products are also implicated in this pathway. Lin-2 encodes a MAGUK and lin-7 encodes a small protein with one PDZ domain. The lin-10 product has no homology to known proteins. Here, we have cloned a rat homologue of the lin-10 product and characterized it. Rat lin-10 is ubiquitously expressed in various rat tissues and distributed in both the cytosol and membrane fractions. In brain, however, rat lin-10 is distributed only in the membrane fraction and enriched in the synaptic plasma membrane and postsynaptic density fractions. These results suggest that rat lin-10 is involved at least in synaptic functions in brain.

Animals↗
PubMed1998

Telomerase activity in hepatocellular carcinoma and adjacent liver tissues.

BACKGROUND AND OBJECTIVES: Activation of telomerase and stabilization of telomeres are considered necessary for immortalization of tumor cells. Telomerase activity was analyzed in 69 hepatocellular carcinomas and adjacent chronic liver disease tissues. The telomerase activity level was examined in relation to clinicopathologic features. METHODS: Telomerase activity was determined by a telomeric repeat amplification protocol. Immature and mature leukocytes were removed from homogenized tissue of adjacent livers using anti-CD45 and anti-CD15 monoclonal antibody-coated magnetic beads. RESULTS: Telomerase activity was detected in hepatocellular carcinomas and leukocytes, but not in liver cells from adjacent chronic liver disease tissues after the separation of leukocytes. All hepatocellular carcinomas displayed telomerase activity, and the activity level correlated with the degree of differentiation (P=0.021) and patient survival (P=0.039). CONCLUSIONS: These results indicate that activation of telomerase may be required as a critical step in hepatocarcinogenesis and tumor development, and detection of telomerase activity with removal of contaminating leukocytes may be useful in the characterization or prognostication of hepatocellular carcinoma.

Adult↗