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Biomedical subjects

J Katayama

Publications and source records attributed to J Katayama.

At least 19 recordsLinked to original sources
PubMed2001

Increased expression of queuosine synthesizing enzyme, tRNA-guanine transglycosylase, and queuosine levels in tRNA of leukemic cells.

Queuosine is a modified nucleoside located at the first position of the tRNA anticodon, which is synthesized by tRNA-guanine transglycosylase (TGT). Although the levels of queuosine in cancer cells have been reported to be lower than those in normal cells, the expression levels of TGT remain to be determined. We determined the expression levels of a subunit of TGT (TGT60KD). Contrary of our expectations, the results revealed higher levels of expression of TGT60KD than that in normal cells, and the level of queuosine in the tRNA fraction corresponded with that of TGT60KD expression. These results suggest the possibilities that the expression levels of TGT60KD regulate TGT activity and the levels of queuosine, and that TGT60KD plays significant roles in carcinogenesis. To our knowledge, this is a first report of increased expression levels of TGT60KD in human cancer cells.

Humans↗
PubMed2000

A transposon carrying the gene mphB for macrolide 2'-phosphotransferase II.

The mphB gene for macrolide 2'-phosphotransferase II is located on two plasmids, pTZ3721 and pTZ3723, in Escherichia coli BM2506. We examined translocation of mphB that originated from pTZ3721. The transposable element carrying mphB is 39 kb long and has a Tn21-like transposition module at one end and a Tn1721-like transposition module at other. The structure of the transposition modules of this element resembles that of Tn2610. However, the gene arrangement of the internal region on the transposon carrying mphB was reverse to that of Tn2610. The nucleotide sequences of both terminal regions suggested that the inversion of the DNA fragment occurred between the res sites by resolvase-mediated recombination.

Amino Acid Sequence↗
PubMed2000

Changes of the thromboxane A2/prostacyclin balance in the urine of patients with renal diseases analyzed by gas chromatography/selected ion monitoring.

The thromboxane A2/prostacyclin (TX/PGI) ratios were measured in patients with renal diseases to elucidate the relationship between the ratios and the pathological changes of the diseases. Urinary stable metabolites of thromboxane A2 and prostacyclin, 11-dehydro-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1alpha, respectively, were converted to 1-methyl ester-propylamide-9,12,15-tris-dimethylisopropylsilyl ether derivative and 1-methyl ester-6-methoxime-9,12,15-tris-dimethylisopropylsilyl ether derivative, respectively, and applied to a gas chromatography/selected ion monitoring. The TX/PGI ratios of 10 outpatients and 6 inpatients with chronic glomerulonephritis were higher than those of 13 healthy volunteers. In an inpatient with systemic lupus erythematoides, the TX/PGI ratios were gradually lowered to the normal level with the therapies. Furthermore, the ratios seemed to change in advance of the changes of the levels of urinary protein and hematuria. These observations suggested that the TX/PGI ratio was a useful index to assess the pathological condition of renal diseases and the effects of treatment.

Adult↗
PubMed2000

Regulation of transcription of the mph(A) gene for macrolide 2'-phosphotransferase I in Escherichia coli: characterization of the regulatory gene mphR(A).

The synthesis of macrolide 2'-phosphotransferase I [Mph(A)], which inactivates erythromycin, is inducible by erythromycin. The expression of high-level resistance to erythromycin requires the mph(A) and mrx genes, which encode Mph(A) and an unidentified protein, respectively. We have studied the mphR(A) gene, which regulates the inducible expression of mph(A). An analysis of the synthesis of Mph(A) in minicells and results of a complementation test indicated that mphR(A) is located downstream from mrx and that its product, MphR(A), represses the production of Mph(A). DNA sequencing indicated that the mph(A), mrx, and mphR(A) genes exist as a cluster that begins with mph(A) and that the deduced amino acid sequence of MphR(A) can adopt an alpha-helix-turn-alpha-helix structure. To study the regulation of gene expression by MphR(A), we performed Northern blotting and primer extension. A transcript of 2. 9 kb that corresponded to the transcript of mph(A) through mphR(A) was detected, and its level was elevated upon exposure of cells to erythromycin. Gel mobility shift assays and DNase I footprinting indicated that MphR(A) binds specifically to the promoter region of mph(A), and the amount of DNA shifted as a results of the binding of MphR(A) decreased as the concentration of erythromycin was increased. These results indicate that transcription of the mph(A)-mrx-mphR(A) operon is negatively regulated by the binding of a repressor protein, MphR(A), to the promoter of the mph(A) gene and is activated upon inhibition of binding of MphR(A) to the promoter in the presence of erythromycin.

Amino Acid Sequence↗
PubMed2000

[Drug Compliance Scale. I. Development of the Drug Compliance Scale].

The failure of patients to comply with treatment regimens recommended by their physicians is a significant clinical problem. Researches on the assessment of compliance have, however, been precluded by methodological difficulties such as lack of adequate measures. The purpose of this study was to develop a self-administered questionnaire to evaluate drug compliance. First, questionnaire containing a 52-items complied by two doctors, a pharmacist and a nurse, was tested on 81 outpatients, all volunteers, attending the departments of psychosomatic medicine and internal medicine. Four items were temporarily removed for later analysis because they directly inquired about drug compliance (drug compliance items). The other 48 items were analyzed and three factors consisting of 26 items were further studied: expectation on taking medicine, rejection to taking medicine and seeking knowledge of drugs. Chronback's alpha coefficients representing internal consistency of the three factors were sufficiently high (ranging from .75 to .84). Furthermore, we preformed a simplified pill count to validate the 4 drug compliance items. There was a weak to moderate correlation between the result of pill count and each of 4 drug compliance items. A new self-administered questionnaire of 30 items was thus developed and named the Drug Compliance Scale.

Drug Administration Schedule↗
PubMed2000

[Drug Compliance Scale. II. Psychological factors affecting drug compliance in the department of psychosomatic medicine].

The purpose of this study was to investigate psychological factors affecting drug compliance in the department of psychosomatic medicine. Seventy-four outpatients were asked to answer a battery of self-administered questionnaire including the Drug Compliance Scale (DCS) that we had recently developed and other questionnaire evaluating psychological and vegetative symptoms, self-efficacy and attributional styles on the promotion of health and personality closely related to interpersonal relationships. Results of path analysis indicated that attributional styles and self-efficacy mainly affected three factors of DCS such as expectation on taking medicine, rejection to taking medicine and seeking knowledge of drugs, through which they influenced drug compliance, and also indicated that personality and self-efficacy mainly affected the stability of mood state, suggesting a further influence on drug compliance.

Adolescent↗
PubMed1999

Excitatory amino acid responses in relay neurons of the rat lateral geniculate nucleus.

Responses to glutamate receptor agonists were recorded from identified relay neurons in the dorsal lateral geniculate nucleus of the rat, using the nystatin-perforated patch-clamp technique. Rapid application of glutamate, N-methyl-D-aspartate, (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and kainate induced inward currents at a holding potential of -44 mV. The responses to low concentrations of each agonist were composed only of steady-state currents, but the responses to high concentrations were additionally composed of a rapid transient peak component except in the kainate-induced current. The currents induced by 10(-3)M N-methyl-D-aspartate in the external solution containing 0 mM Mg2+ and 10(-6)M glycine were reduced in amplitude when the external solution contained 1 mM Mg2+, and were abolished when the solution contained no glycine. The currents induced by a neurotransmitter candidate at retinogeniculate synapses, N-acetyl-aspartyl-glutamate, were markedly reduced in amplitude when the solution contained 1 mM Mg2+ or 10(-4)M DL-2-amino-5-phosphonovaleric acid. The current abolished in the Mg2+-containing, glycine-free solution (N-methyl-D-aspartate component) and the current remaining in the same solution (non-N-methyl-D-aspartate component) of the N-acetyl-aspartyl-glutamate response were both increased in a concentration-dependent manner, as the N-acetyl-aspartyl-glutamate concentration was increased. The current-voltage relationship of the currents induced by N-methyl-D-aspartate and N-acetyl-aspartyl-glutamate was characterized by Mg2+-dependent block at hyperpolarized potentials. The inward currents induced by 3 x 10(-4)M AMPA and 3 x 10(-4)M glutamate were markedly potentiated by 10(-4)M cyclothiazide, but the currents induced by 3 x 10(-4)M kainate and 10(-3)M N-acetyl-aspartyl-glutamate (non-N-methyl-D-aspartate component) were little affected. The currents induced by any agonist were not affected by 3 x 10(-4)g/ml concanavalin A. The current induced by 10(-4)M kainate was markedly suppressed by pretreatment with 10(-4)M AMPA or 10(-4)M glutamate, but only weakly by 10(-3)M N-acetyl-aspartylglutamate. The Ca2+ permeability (PCa/PCs) of the N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors was 9.57 and 0.16, respectively. These results suggest that dorsal lateral geniculate nucleus relay neurons of the rat possessed both Ca2+-permeable N-methyl-D-aspartate receptors and less permeable non-N-methyl-D-aspartate (presumably AMPA) receptors, and that N-acetyl-aspartyl-glutamate mainly acts at N-methyl-D-aspartate receptors with a weak kainate-like action on non-N-methyl-D-aspartate receptors.

Animals↗
PubMed1999

Auditory and visual P300 topography from a 3 stimulus paradigm.

OBJECTIVE: The P300 event-related brain potential (ERP) was elicited with auditory and visual stimuli in a separate session of a 3 stimulus oddball paradigm, and the scalp topography was assessed with 15 electrode locations. METHODS: Target (0.10), standard (0.80), and infrequent non-target (0.10) stimuli in the auditory task were 2000, 1000 and 500 Hz tone, and in the visual task, 'X', 'O', and 'H', respectively. The stimuli were presented in a random series, once every 2 s, and participants responded only to the target (N = 12). RESULTS: Target stimuli elicited larger P300 components than non-target did in both stimulus modalities. For both target and non-target stimuli, P300 amplitude was larger and latency longer for the visual compared with the auditory stimulus. Analysis of normalized P300 amplitude data indicated that the target and non-target P300s from both modalities had identical topography. CONCLUSION: The findings suggest that both target and non-target stimuli in 3 stimulus oddball paradigm elicited the same type of P300 (P3b) for both stimulus modalities.

Acoustic Stimulation↗
PubMed1999

Nucleotide sequence of the gene cluster containing the mphB gene for macrolide 2'-phosphotransferase II.

Escherichia coli BM2506 produced macrolide 2'-phosphotransferase II [MPH (2') II]. A gene for MPH (2') II, designated mphB, is located on plasmids pTZ3721 and pTZ3723 in E. coli BM2506. In the present study, we determined the nucleotide sequence of the 6.5-kb EcoRI-PstI fragment containing mphB on pTZ3721. The DNA region of 6.5-kb EcoRI-PstI fragment contained five open reading frames (ORFs). ORF4 corresponded to mphB. Respective products deduced from ORF1, ORF2, ORF3, and ORF5 were similar to the penicillin-binding protein 4 of Streptomyces lactamduras, the repressor protein AcrR of the acrAB operon, the enzyme RdmC involved in the biosynthesis of the antibiotic aklavinone, and IS801 transposase-like protein from Pseudomonas pseudoalcakigenes, respectively. Among these genes, ORF2, ORF3, and mphB formed a gene cluster with ORF2 in the lead sequence. Our results suggest that mphB may originate from an operon related to antibiotic biosynthesis.

Base Sequence↗
PubMed1998

Expression of the mphB gene for macrolide 2'-phosphotransferase II from Escherichia coli in Staphylococcus aureus.

The genes mphA and mphB encode macrolide 2'-phosphotransferases I and II, respectively, and they confer resistance to macrolide antibiotics in Escherichia coli. To study the expression of these genes in Gram-positive bacteria, we constructed recombinant plasmids that consisted of an mph gene and the pUB110 vector in Bacillus subtilis. When these plasmids were introduced into Staphylococcus aureus, the mphB gene was active and macrolide 2'-phosphotransferase II was produced. The gene endowed S. aureus with high-level resistance to spiramycin, a macrolide antibiotic with a 16-membered ring. Moreover, transcription of the mphB gene in S. aureus began at the promoter that was active in E. coli.

Escherichia coli↗
PubMed1998

ERPs, semantic processing and age.

ERPs (N400, LPC and CNV) were elicited in two sets of subjects grouped according to age (young vs. elderly) using a word-pair category matching paradigm. Each prime consisted of a Japanese noun (constructed from two to four characters of the Hiragana) followed by one Chinese character (Kanji) as the target, this latter representing one of five semantic categories. There were two equally probable target conditions: match or mismatch. Each target was preceded by a prime, either belonging to, or not belonging to, the same semantic category. The subjects were required to respond with a specified button press to the given target according to the condition. We found RTs to be longer in the elderly subjects and under the mismatch condition. N400 amplitude was reduced in the elderly subjects under the mismatch condition and there was no difference between match and mismatch response, which were similar in amplitude to that under match condition for the young subjects. In addition, the CNV amplitudes were larger in the elderly subjects. These results suggested that functional changes in semantic processing through aging (larger semantic networks and diffuse semantic activation) were the cause of this N400 reduction, attributing a subsidiary role to attentional disturbance. We also discuss the importance of taking age-related changes into consideration in clinical studies.

Adult↗
PubMed1998

Expression in Pseudomonas aeruginosa of an erythromycin-resistance determinant that encodes the mphA gene for macrolide 2'-phosphotransferase I from Escherichia coli.

We studied the expression in Pseudomonas aeruginosa of an erythromycin-resistance (EMr) determinant that included the mphA gene for macrolide 2'-phosphotransferase I and originated in Escherichia coli. A recombinant plasmid, pTZ3609, that consisted of the EMr determinant and a broad-host-range vector RSF1010, endowed P. aeruginosa with high-level resistance to erythromycin. Furthermore, the EMr determinant on a self-transferable plasmid, RP1, was transferred from E. coli to P. aeruginosa by conjugation.

Anti-Bacterial Agents↗
PubMed1998

Isolation and characterization of two plasmids that mediate macrolide resistance in Escherichia coli: transferability and molecular properties.

Escherichia coli BM2506 is highly resistant to macrolide antibiotics; it produces macrolide 2'-phosphotransferase II [MPH(2')II] which inactivates such drugs. We investigated the localization and the transfer of the macrolide-resistance determinant that encoded the mphB gene for MPH(2')II in strain BM2506. Although we detected no clear band of plasmid DNA after agarose gel electrophoresis, transformation analysis using satellite DNA that corresponded to plasmid DNA after CsCl-ethidium bromide gradient centrifugation and restriction analysis of plasmid DNA in transformants showed that strain BM2506 harbored two plasmids, pTZ3721 (84 kb) and pTZ3723 (24 kb), that specified resistance to macrolides, ampicillin, streptomycin, tetracycline and sulfonamide and to macrolides and ampicillin, respectively. Southern hybridization showed that the mphB gene hybridized to both plasmids. Furthermore, pTZ3721 was transferred by conjugation to another strain of E. coli and pTZ3723 was mobilized with a self-transferable plasmid RP1 to other strains of E. coli. Therefore, it appears that the mphB gene is located on two plasmids in BM2506 and can be transferred to other strains of E. coli by conjugation or mobilization.

Anti-Bacterial Agents↗
PubMed1998

Stimulus context determines P3a and P3b.

P300 differences for target (.10), nontarget (.10), and standard tones (.80) were assessed using a three-stimulus oddball paradigm in which participants responded only to the target (n = 12). Target/standard (easy or difficult) and nontarget/standard (large or small) pitch differences were manipulated orthogonally. In all conditions, target tones elicited a parietal P300, which was affected only by the target/standard discrimination ease. Nontarget in the easy/large and difficult/small conditions elicited a parietal but smaller P300 than the target but in the easy/small condition elicited similar ERPs to the standard. However, nontarget stimuli in the difficult/large condition elicited an anterior maximum and earlier P300 (P3a) component. The findings suggest that target P300s are not influenced by the nontarget stimulus configuration, whereas the nontarget P300 outcomes are determined directly by the stimulus context. The theoretical implications are discussed.

Acoustic Stimulation↗
PubMed1997

A solid-phase assay to screen monoclonal antibodies against DNA-binding protein.

A method is described for selecting monoclonal antibodies (mAb) against DNA-binding protein. The protocol involves a non-radioactive solid-phase DNA binding assay using a 96-well plate. Because the solid-phase assay is highly specific and sensitive, partially purified antigen is sufficient for the immunization, and mAb screening can be performed with crude cell extract as the antigen. MAbs obtained by this method could supershift the DNA-protein complex in the electromobility shift assay, and were sufficient for immunoscreening of a cDNA expression library.

Animals↗
PubMed1997

Characterization of the K+ current mediated by 5-HT1A receptor in the acutely dissociated rat dorsal raphe neurons.

The action of 5-hydroxytryptamine (5-HT) via the 5-HT1A receptor on dissociated rat dorsal raphe neurons was characterized under the whole-cell mode by using the nystatin-perforated patch-clamp technique. Under voltage-clamp conditions, 5-HT induced an inwardly rectifying K+ current (I5-HT) in a concentration-dependent manner. I5-HT was mimicked by 8-OH-DPAT and buspirone, which are both 5-HT1A receptor agonists. I5-HT was reversibly blocked by such 5-HT1A receptor antagonists as (S)-UH-301 a 5-HT4 receptor antagonist. I5-HT was antagonized concentration-dependently by such K+ channel blockers as quinine, Ba2+ and 4-aminopyridine but was relatively insensitive to both CS+ and tetraethylammonium. When the neurons were loaded with guanosine 5'-O-3-thiotriphosphate through a patch pipette, the K+ current induced by 5-HT became irreversible. N-ethylmaleimide (NEM), a sulfhydryl alkylating agent, irreversibly blocked I5-HT. The intracellular perfusion with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a Ca2+ chelator, or neomycine, a phospholipase C inhibitor, never significantly affected the 5-HT-induced response. 12-Myristate 13-acetate diester (PMA), a protein kinase C (PKC) activator, had only a weak inhibitory effect on I5-HT, and staurosporine, a PKC inhibitor, failed to significantly occlude I5-HT. Therefore, the K+ conductance activated via the 5-HT1a receptor of dorsal raphe neurons was thus characterized by the sensitivity to such K+ channel blockers as quinine, Ba2+ and 4-aminopyridine. Moreover, G protein which is NEM-sensitive and can couple to the 5-HT1A receptor, is thus considered to activate the inwardly rectifying K+ conductance without being mediated by such second messengers as Ca2+ and PKC.

Animals↗
PubMed1997

Discovery of a novel thrombopoietin mimic agonist peptide.

A random phage peptide library was constructed for the filamentous bacteriophage fuse5. The library was made by inserting a degenerate oligonucleotide which encodes 15 variable amino acids into the NH2-terminal region of the phage gene III protein. This library, containing 1x10(9) different phages, was screened with a human immunoglobulin fusion protein containing the extracellular region of human thrombopoietin receptor. Several phages were isolated following four cycles of enrichment and amplification. These phages specifically bound to the fusion protein. One phage peptide acted as an agonist of the thrombopoietin receptor, since it stimulated the proliferation of thrombopoietin-dependent cells and the differentiation of mouse bone marrow cells to megakaryocytes. The amino acid sequence of this peptide is not present in the primary amino acid sequence of thrombopoietin. This discovery may lead to the design of a small-molecular mimic of thrombopoietin.

Amino Acid Sequence↗