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Biomedical subjects

S Nagata

Publications and source records attributed to S Nagata.

At least 559 records · Page 31Linked to original sources
PubMed1990

Improvement in mitral flow dynamics during exercise after percutaneous transvenous mitral commissurotomy. Noninvasive evaluation using continuous wave Doppler technique.

Evaluation of mitral flow dynamics during exercise is critically important in patients who receive percutaneous transvenous mitral commissurotomy (PTMC) because limited mitral flow during exercise provokes hemodynamic deterioration and involves cardiogenic symptoms in patients with mitral stenosis. To examine mitral flow dynamics during exercise, we applied continuous wave Doppler technique in 20 patients with mitral stenosis. Exercise Doppler study was performed 2 days before and 5 days after PTMC. PTMC increased mitral valve area from 1.0 +/- 0.3 (mean +/- SD) to 1.9 +/- 0.5 cm2 and decreased mean transmitral pressure gradient from 8 +/- 2 to 4 +/- 1 mm Hg at rest. Moreover, PTMC decreased mean transmitral pressure gradient from 21 +/- 6 to 11 +/- 4 mm Hg at submaximal exercise. The extent of an increase in mitral valve area by PTMC correlated with a decrease in the mean transmitral pressure gradient at the submaximal exercise (r = -0.76, p less than 0.01) and that at rest (r = -0.52, p less than 0.05). Heart rate after PTMC during exercise was significantly lower than that before PTMC, indicating that the compensatory mechanism (tachycardia) to increase cardiac output during exercise is less necessary after PTMC. Thus, we conclude that the mitral flow dynamics during exercise is improved, as well as the resting mitral flow dynamics 5 days after PTMC, and that exercise Doppler study enabled us to make a noninvasive evaluation of the mitral flow dynamics in patients who receive PTMC.

Adult↗
PubMed1990

Improvement in pulmonary function in mitral stenosis after percutaneous transvenous mitral commissurotomy.

Before and after percutaneous transvenous mitral commissurotomy (PTMC), pulmonary function studies were performed in 25 patients with mitral stenosis, in order to determine the effects of pulmonary hemodynamics on pulmonary function in patients with mitral stenosis. After PTMC, dramatic improvements in pulmonary hemodynamics were seen in all patients. With regard to pulmonary function data, the VC as percent predicted value increased from 87.6 +/- 16.1 percent to 94.7 +/- 14.4 percent (p less than 0.001). Although the ratio of FEV1/FVC was unchanged, the MVV as percent predicted value increased, and the ratio of RV/TLC, CV, and the difference in nitrogen concentration between 750 ml and 1,250 ml of expired volume decreased significantly. According to the maximum expiratory flow-volume curves, V ax 50% and Vmax 25% improved. Despite marked improvements in pulmonary ventilatory function soon after PTMC, the percent predicted diffusing capacity of the lung for carbon monoxide decreased significantly after PTMC. Arterial blood gas data, such as the partial pressure of oxygen and carbon dioxide in arterial blood and the alveolar-arterial differences in partial pressure of oxygen, did not improve within one or two weeks after PTMC. We conclude that in mitral stenosis, the majority of ventilatory function impairments are caused by hemodynamic alterations that are mainly reversible.

Adult↗
PubMed1990

Expression of granulocyte and granulocyte-macrophage colony-stimulating factors by human non-hematopoietic tumor cells.

The expression of granulocyte colony-stimulating factor (G-CSF) mRNA was studied in human non-hematopoietic tumors, including 18 cases of lung cancers 10 cases of stomach cancers, three cases of glioblastomas, and one case each of breast phyllode sarcoma, thyroid cancer, and hepatocellular carcinoma. Northern blot analysis detected G-CSF mRNA in two of the lung cancer cases, in one of the glioblastoma cases, and in both the breast phyllode sarcoma and hepatocellular carcinoma cases. Since G-CSF receptors were not detected on the tumor cells by 125I-G-CSF binding assay, G-CSF autocrine loop are probably not involved in the growth of these G-CSF-producing tumors. Interestingly, granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA was concomitantly expressed in most of these G-CSF-producing tumors. No major gene deletions or rearrangements of G-CSF and GM-CSF genes were demonstrated by Southern blot analysis in the tumors expressing G-CSF and GM-CSF mRNAs except for one of the glioblastomas (G3) in which one chromosome 17 allele was deleted. Although the mechanism of the concomitant expression of G-CSF and GM-CSF mRNA is unknown, relatively high frequency of this phenomenon suggests the presence of common transcriptional factors acting on regulatory regions of G-CSF and GM-CSF genomes.

Cell Line↗
PubMed1990

Selective determination of L-lysine with L-lysine epsilon-dehydrogenase.

Simple and sensitive spectrophotometric methods were developed for the selective determination of L-lysine. The assay methods were based on the spectrophotometric determination of NADH formed in the reaction catalyzed by L-lysine epsilon-dehydrogenase (Procedure A) or the formazan produced on coupling of the dehydrogenase reaction with the reduction of a tetrazolium salt (Procedure B). Procedure B was applicable to the direct determination of L-lysine in rabbit serum.

Amino Acid Oxidoreductases↗
PubMed1990

Leucine dehydrogenase from Corynebacterium pseudodiphtheriticum: purification and characterization.

Leucine dehydrogenase [EC 1.4.1.9] was purified to homogeneity from Corynebacterium pseudodiphtheriticum ICR 2210. The enzyme consisted of a single polypeptide with a molecular weight of about 34,000. Stepwise Edman degradation provided the N-terminal sequence of the first 24 amino acids, and carboxypeptidase Y digestion provided the C-terminal sequence of the last 2 amino acids. Although the enzyme catalyzed the reversible deamination of various branched-chain L-amino acids, L-valine was the best substrate for oxidative deamination at pH 10.9 and the saturated concentration. The enzyme, however, had higher reactivity for L-leucine, and the kcat/Km value for L-leucine was higher than that for L-valine. The enzyme required NAD+ as a natural coenzyme. The NAD+ analogs 3-acetylpyridine-NAD+ and deamino-NAD+ were much better coenzymes than NAD+. The enzyme activity was significantly reduced by sulfhydryl reagents and pyridoxal 5'-phosphate. D-Enantiomers of the substrate amino acids competitively inhibited the oxidation of L-valine.

Amino Acid Oxidoreductases↗
PubMed1990

Cloning and expression of endo-beta-1,3-glucanase gene from Flavobacterium dormitator in Escherichia coli and characterization of the gene product.

The beta-1,3-glucanase (1,3-beta-D-glucan glucanohydrolase, EC 3.2.1.6) gene from Flavobacterium dormitator var. glucanolyticae was cloned into Escherichia coli C600 with a vector plasmid, pBR322. The E. coli cells carrying a recombinant plasmid, pKU beta G1 (8.2 kb), showed a high beta-1,3-glucanase activity and a lytic activity on viable yeast cells. These activities were found in the periplasmic space of E. coli clone cells. Southern hybridization analysis showed that the cloned gene was derived from F. dormitator chromosomal DNA. The gene products were purified from the periplasmic fraction of E. coli by ammonium sulfate fractionation and ion-exchange chromatography. The purified enzymes were demonstrated to be identical with a lytic endo-beta-1,3-glucanase II and a nonlytic endo-beta-1,3-glucanase I from F. dormitator from their enzymological and immunological properties. In the E. coli cells, endo-beta-1,3-glucanase I was also formed by a proteolytic digestion of endo-beta-1,3-glucanase II during the cultivation as in F. dormitator. Thus, the only endo-beta-1,3-glucanase II was coded for in the cloned gene.

Cloning, Molecular↗
PubMed1990

[Doppler echocardiographic features of the atrial and ventricular filling modes and their significance in restrictive myocardial diseases].

The filling modes into the right atrium and both ventricles were observed using pulsed Doppler echocardiography in six cases of restrictive myocardial diseases, and these were compared with those of 13 cases of constrictive pericarditis, six cases of lone atrial fibrillation and 16 healthy subjects. Special attention was paid to the mechanical properties of the cardiac walls which might be reflected in the filling modes. 1. In the restrictive cases, right atrial filling from the superior caval vein during ventricular systole was reduced in velocity and duration, but the atrial filling during ventricular diastole was not appreciably changed. This flow pattern was similar to that of lone atrial fibrillation, indicating reduced distensibility or impaired contraction and ejection fraction of the right atrium. In constrictive pericarditis, the right atrial filling time was shortened both in ventricular systole and diastole, reflecting stiffening of the pericardium. 2. In the restrictive cases, the first half of the left ventricular rapid filling wave was steep and the skirt of the descending limb was prolonged, while there was no such tendency in the right ventricle. In constrictive pericarditis, the rapid filling time was shortened in the right ventricle, and was not significantly changed in the left ventricle. 3. The differences in the atrial and ventricular filling patterns between restrictive myocardial disease and constrictive pericarditis may serve to distinguish these two disease entities.

Adult↗
PubMed1990

[Assessment of myocardial damage in cardiomyopathy using 111In-antimyosin Fab myocardial scintigraphy].

111In-antimyosin Fab (AM) myocardial scintigraphy was carried out in (A) 10 patients with idiopathic dilated cardiomyopathy, (B) 7 with dilated phase of hypertrophic cardiomyopathy and (C) 8 with normal (control) individuals. Imaging was taken 48 hours after intravenous injection of 74 MBq of AM. Myocardial uptake of AM was evaluated qualitatively and quantitatively. Positive uptake was observed in 9/10 (90%), 7/7 (100%) and 0/8 (0%) in group A, B and C, respectively. AM index (heart/lung ratio) in group A and B were 2.04 +/- 0.24 and 2.46 +/- 0.49, values significantly higher than that obtained in the control patient without cardiomyopathy (1.51 +/- 0.13) (p less than 0.01). Positive monoclonal antimyosin antibody studies were highly prevalent in dilated cardiomyopathic and dilated phase of hypertrophic cardiomyopathic patients, even in the presence of negative right ventricular biopsy. It is suggested that this method was useful for the noninvasive assessment of active myocardial damage in these patients.

Adult↗
PubMed1990

[Progression of idiopathic mitral valve prolapse estimated by echocardiography].

To evaluate the progression of idiopathic mitral valve prolapse (MVP), a long time follow-up study (mean 7.1 years) was performed using echocardiography in 27 cases (11 males, 16 females, mean age: 50.4 years). Morphological changes, the degree of prolapse of the mitral valve, left atrial dimension (LAD) and left ventricular end-diastolic dimension (LVDd) were estimated at the first and last examinations. The degree of prolapse was assessed by measuring the distance of the dislocation between the anterior and posterior leaflets at the area of coaptation (degree I:5 mm or less, degree II: 6 to 10 mm, degree III: 11 mm or greater). The results were as follows: 1. The degree of prolapse did not progress in all 27 cases. 2. LAD increased with an advance of age. A remarkable increase of LAD was recorded in cases older than 45 years with atrial fibrillation or prolapse of degree II and III or with ruptured chordae tendineae. 3. The mitral ring was enlarged over 5 mm in six of 15 cases with prolapse of degree II and III. 4. Mitral regurgitation evaluated by Doppler echocardiography in patients with posterior leaflet prolapse was more severe than that in patients with anterior leaflet prolapse in the last examination. 5. LVDd increased gradually. In the present study, LAD was increased in most cases of MVP and it seemed to depend on complications (atrial fibrillation and ruptured chordae tendineae) or severity of regurgitation rather than the degree of prolapse.

Adult↗
PubMed1989

Molecular cloning and characterization of a chromosomal gene for human eosinophil peroxidase.

Using human myeloperoxidase cDNA as a probe, a chromosomal gene related to myeloperoxidase was isolated from a human gene library. Comparison of the amino acid sequence deduced from the nucleotide sequence of the cloned gene with that of human eosinophil peroxidase purified from buffy coats has indicated that the isolated gene is the chromosomal gene for human eosinophil peroxidase. Like human myeloperoxidase gene, human eosinophil peroxidase gene consists of 12 exons and 11 introns spanning about 12 kilobases. The gene can code for a protein of 715 amino acids with a calculated Mr of 81,036. The heavy chain and the light chain of eosinophil peroxidase were located on the COOH and NH2 terminus of the protein, respectively. The coding sequences of eosinophil peroxidase and myeloperoxidase show homologies of 72.4% at the nucleotide and 69.8% at the amino acid level, while little homology was found in the 5'-flanking region. Northern hybridization and S1 mapping analysis of RNA from human leukemic cells have indicated that the eosinophil peroxidase gene is expressed in the eosinophilic subline of human HL-60 cells but not in the neutrophilic subline or in parental HL-60 cells.

Amino Acid Sequence↗
PubMed1989

The beta subunit of tryptophan synthase. Clarification of the roles of histidine 86, lysine 87, arginine 148, cysteine 170, and cysteine 230.

Our studies, which are aimed at understanding the catalytic mechanism of the beta subunit of tryptophan synthase from Salmonella typhimurium, use site-directed mutagenesis to clarify the functional roles of several putative active site residues. Although previous chemical modification studies have suggested that histidine 86, arginine 148, and cysteine 230 are essential residues in the beta subunit, our present findings that beta subunits with single amino acid replacements at these positions have partial activity show that these 3 residues are not essential for catalysis or substrate binding. These conclusions are consistent with the recently determined three-dimensional structure of the tryptophan synthase alpha 2 beta 2 complex. Amino acid substitution of lysine 87, which forms a Schiff base with pyridoxal phosphate in the wild type beta subunit, yields an inactive form of the beta subunit which binds alpha subunit, pyridoxal phosphate, and L-serine. We also report a rapid and efficient method for purifying wild type and mutant forms of the alpha 2 beta 2 complex from S. typhimurium from an improved enzyme source. The enzyme, which is produced by a multicopy plasmid encoding the trpA and trpB genes of S. typhimurium expressed in Escherichia coli, is crystallized from crude extracts by the addition of 6% poly(ethylene glycol) 8000 and 5 mM spermine. This new method is also used in the accompanying paper to purify nine alpha 2 beta 2 complexes containing mutant forms of the alpha subunit.

Arginine↗
PubMed1989

The alpha subunit of tryptophan synthase. Evidence that aspartic acid 60 is a catalytic residue and that the double alteration of residues 175 and 211 in a second-site revertant restores the proper geometry of the substrate binding site.

Our studies, which are aimed at understanding the catalytic mechanism of the alpha subunit of tryptophan synthase from Salmonella typhimurium, use site-directed mutagenesis to explore the functional roles of aspartic acid 60, tyrosine 175, and glycine 211. These residues are located close to the substrate binding site of the alpha subunit in the three-dimensional structure of the tryptophan synthase alpha 2 beta 2 complex. Our finding that replacement of aspartic acid 60 by asparagine, alanine, or tyrosine results in complete loss of activity in the reaction catalyzed by the alpha subunit supports a catalytic role for aspartic acid 60. Since the mutant form with glutamic acid at position 60 has partial activity, glutamic acid 60 may serve as an alternative catalytic base. The mutant form in which tyrosine 175 is replaced by phenylalanine has substantial activity; thus the phenolic hydroxyl of tyrosine 175 is not essential for catalysis or substrate binding. Yanofsky and colleagues have identified many missense mutant forms of the alpha subunit of tryptophan synthase from Escherichia coli. Two of these inactive mutant forms had either tyrosine 175 replaced by cysteine or glycine 211 replaced by glutamic acid. Surprisingly, a second-site revertant which contained both of these amino acid changes was partially active. These results indicated that the second mutation must compensate in some way for the first. We now extend the studies of the effects of specific amino acid replacements at positions 175 and 211 by two techniques: 1) characterization of several mutant forms of the alpha subunit from S. typhimurium prepared by site-directed mutagenesis and 2) computer graphics modeling of the substrate binding site of the alpha subunit using the x-ray coordinates of the wild type alpha 2 beta 2 complex from S. typhimurium. We conclude that the restoration of alpha subunit activity in the doubly altered second-site revertant results from restoration of the proper geometry of the substrate binding site.

Aspartic Acid↗
PubMed1989

Isolation and characterization of the human chromosomal gene for polypeptide chain elongation factor-1 alpha.

The cDNA for human elongation factor-1 alpha was isolated from a cDNA library of human fibroblast cells. Using the cDNA as a probe, a number of chromosomal genes encoding the human elongation factor-1 alpha were isolated. Characterization of the clones by restriction enzyme mapping and nucleotide sequence analysis has revealed that only one of them is an active gene, whereas all of the other genes are processed pseudogenes. The active gene consists of 8 exons and 7 introns spanning about 3.5 kilobases, and the sequence of its exons is completely identical to that of the human elongation factor-1 alpha cDNA. The first non-coding exon of 33 base pairs is separated by a 943-base pair intron from the coding exons. The primer extension of human elongation factor-1 alpha mRNA has indicated that the transcription of human elongation factor-1 alpha gene starts from a C residue, and a "TATA" box was found 24 base pairs upstream of the initiation site. Three and five Sp1 binding sites are present on the 5'-flanking region and the 1st intron, respectively. Furthermore, one Ap-1 binding site is located in the 1st intron. By using nuclear extracts from HeLa cells, the promoter of human elongation factor-1 alpha gene could stimulate in vitro transcription better than the adenovirus major late promoter.

Amino Acid Sequence↗
PubMed1989

Gene structure and function of granulocyte colony-stimulating factor.

In the last few years, the molecular and genetic nature of the granulocyte colony-stimulating factor, which controls proliferation and differentiation of neutrophils, has been characterized. Recent clinical application of G-CSF proves that this hormone is effective in the treatment of patients suffering from neutropenia.

Amino Acid Sequence↗
PubMed1989

Surgical treatment for paediatric patients with moyamoya disease by indirect revascularization procedures (EDAS, EMS, EMAS).

Surgical results of paediatric patients with Moyamoya disease who were treated by indirect revascularization procedures are reported. Encephalo-duro-arterio-synangiosis (EDAS), encephalomyo-arterio-synangiosis (EMAS), and/or encephalo-myo-synangiosis (EMS) were performed on 47 sides of 29 children with Moyamoya disease. The results of those non-anastomotic EC-IC bypass procedures were evaluated clinically, angiographically, and by computed tomography (CT). Postoperative external carotid angiograms showed a good collateral formation through EDAS, EMAS, or EMS in about 70-80 percent of all surgically treated sides. The symptoms such as TIA, RIND, and/or involuntary movements disappeared in the cases with a good collateral formation but not in those with insufficient development of the collateral circulation. The indirect EC-IC bypass surgery seems effective for most of the children with Moyamoya disease who present with ischaemic signs.

Angiography↗
PubMed1989

Concurrence of mouthing movement and rapid eye movement/non-rapid eye movement phases with advance in gestation of the human fetus.

To evaluate whether mouthing movement in the human fetus is related to advance in gestational age and whether such movement is concurrent with rapid eye movement or non-rapid eye movement phases, 26 fetuses from 28 to 41 weeks' gestation were observed for 60 continuous minutes with real-time ultrasonography. It was evident that regular mouthing movement every 300 to 600 msec concurred with the non-rapid eye movement period, from 35 weeks' gestation to term. Random mouthing movements that occurred at a wide range of intervals from 300 msec to approximately 525 seconds were observed predominantly during the rapid eye movement period and were unrelated to advance in gestational age. These observations were discussed in relation to biologic implications.

Eye Movements↗