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Biomedical subjects

S Nagata

Publications and source records attributed to S Nagata.

At least 667 records · Page 37Linked to original sources
PubMed1985

Activation of the alternative complement pathway by intraocular lenses.

To determine if posterior chamber polymethylmethacrylate lenses with polypropylene loops activate complement, the authors measured levels of C3a, C4a and C5a by radioimmunoassay in human sera incubated with and without these lenses. Human sera incubated with intraocular lenses showed elevated levels of C3a and C5a but no change in C4a. There were no statistically significant differences in the generation of activated complement by polypropylene loops vs polymethylmethacrylate optics. The authors also compared the ability of intraocular lenses to activate complement with that of zymosan and endotoxin, known activators of the alternative pathway. Our results suggest that polymethylmethacrylate lenses with polypropylene loops generate C3a and C5a by activation of the alternative complement pathway.

Adult↗
PubMed1985

[Two-dimensional echocardiography in diagnosing the region of myocardial infarction: a comparative study by several independent examiners].

The efficacy of two-dimensional echocardiography in diagnosing the localization of myocardial infarction (MI) was studied by comparing the echocardiographic and pathological findings of 28 patients having MI. The ventricular wall was divided into 18 segments including three segments of the right ventricular wall. The regional wall motion abnormalities for each of the 504 segments were diagnosed by visual assessment. The echocardiographic recordings were reviewed individually by four examiners using the same protocol to assess the interobserver's variation. The receiver operating characteristics (ROC) curves differed by examiners. However, when the subjects were limited to anterior MI patients, the ROC curves established by the echo-trained physicians did not differ significantly. It was concluded that the echocardiographic diagnosis of regional wall motion by visual assessment has universal validity. Individual differences are thought mainly to depend on the sites of infarction. Sensitivities for detecting transmural (TM), non-transmural (non-TM) infarcted segments and intact segments were 90, 70 and 70%, respectively. Most of the underestimated TM or overestimated intact segments corresponded to the sites adjacent to MI. As the unexpectedly misdiagnosed segments, the mimic inward motion of the inferior wall drawn by the intact anteroapical wall was observed in a inferior MI patient, or the mimic anterior motion of the anteroapical wall by a swinging motion of the heart, or the paradoxical motion of the interventricular septum was observed in a right ventricular MI case. In the two third of the overestimated non-TM segments, it was considered that the wall motion was affected by the myocardial ischemia, which was not revealed by pathological examination. The underestimated non-TM segments located adjacent to the intact segments or opposite to the severely ischemic segments. From the echocardiographic viewpoint, nearly 90% of segments showing akinetic or dyskinetic motion had MI. However, one third of segments diagnosed as normal were actually MI segments.

Aged↗
PubMed1984

Polypeptide chain elongation factor 1 alpha (EF-1 alpha) from yeast: nucleotide sequence of one of the two genes for EF-1 alpha from Saccharomyces cerevisiae.

Messenger RNA for yeast cytosolic polypeptide chain elongation factor 1 alpha (EF-1 alpha) was partially purified from Saccharomyces cerevisiae. Double-stranded complementary DNA (cDNA) was synthesized and cloned in Escherichia coli with pBR327 as a vector. Recombinant plasmid carrying yEF-1 alpha cDNA was identified by cross-hybridization with the E. coli tufB gene and the yeast mitochondrial EF-Tu gene (tufM) under non-stringent conditions. A yeast gene library was then screened with the EF-1 alpha cDNA and several clones containing the chromosomal gene for EF-1 alpha were isolated. Restriction analysis of DNA fragments of these clones as well as the Southern hybridization of yeast genomic DNA with labelled EF-1 alpha cDNA indicated that there are two EF-1 alpha genes in S. cerevisiae. The nucleotide sequence of one of the two EF-1 alpha genes (designated as EF1 alpha A) was established together with its 5'- and 3'-flanking sequences. The sequence contained 1374 nucleotides coding for a protein of 458 amino acids with a calculated mol. wt. of 50 300. The derived amino acid sequence showed homologies of 31% and 32% with yeast mitochondrial EF-Tu and E. coli EF-Tu, respectively.

Amino Acid Sequence↗
PubMed1984

Constitutive production of human interferons by mouse cells with bovine papillomavirus as a vector.

Mouse C127I cells were transformed with a chimeric plasmid consisting of bovine papillomavirus and human interferon (HuIFN) gene (either IFN-gamma or IFN-alpha 5) placed under the control of simian virus 40 early promoter. The transformed cells retained 30-50 copies each of the hybrid plasmid extrachromosomally and secreted a high level of HuIFNs constitutively up to 3-4 X 10(5) international units/ml. The secreted HuIFN-gamma had no detectable activity on mouse cells, whereas HuIFN-alpha 5 was slightly active on mouse cells. Each IFN was neutralized either by anti-HuIFN-gamma or anti-HuIFN-alpha antiserum. The partially purified 35S-labeled HuIFN-gamma produced by the transformed cells showed heterogeneous bands with apparent Mrs of 22,000-25,000 on NaDodSO4/polyacrylamide gel electrophoresis. This value is similar to that of natural IFN-gamma and larger than the molecular weight calculated from the amino acid sequence, which suggests that HuIFN-gamma secreted by transformed mouse cells was glycosylated. The 35S-labeled IFN-alpha 5, immunoprecipitated with anti-HuIFN-alpha antiserum from the supernatant of the transformed cells, had a molecular weight of mature protein. These results suggest that the bovine papillomavirus vector can be used to produce a large quantity of foreign proteins in mammalian cells.

Animals↗
PubMed1984

Molecular cloning and nucleotide sequence of cDNA for rat ornithine carbamoyltransferase precursor.

Messenger RNA of rat ornithine carbamoyltransferase (EC 2.1.3.3), a mitochondrial matrix enzyme, was enriched by immunoprecipitation of rat liver free polysomes, and recombinant plasmids were prepared from the enriched mRNA by a vector-primer method. The cDNA clones for ornithine carbamoyltransferase were identified by hybrid-arrested translation and hybrid-selected translation. One of the clones, designated pOTC-1, contained a 1.6-kilobase insert and hybridized to a mRNA of approximately equal to 1.8 kilobases in rat liver. The cDNA clone was subjected to nucleotide sequence analysis. The deduced amino acid sequence indicates that the ornithine carbamoyltransferase precursor consists of the mature enzyme of 322 amino acid residues and an NH2-terminal peptide extension (presequence) of 32 amino acid residues. The presequence contains 8 basic amino acid residues, no acidic residues, and no hydrophobic amino acid stretch. The amino acid sequence of the rat ornithine carbamoyltransferase was compared with the recently reported sequence of the human enzyme [Horwich, A. L., Fenton, W. A., Williams, K. R., Kalousek, F., Kraus, J. P., Doolittle, R. F., Konigsberg, W. & Rosenberg, L. E. (1984) Science 224, 1068-1074]. The sequences of the mature enzyme portion are 93% identical, whereas those of the presequences are 69% identical. There are two highly conserved segments in the presequences of the rat and human enzymes. One of the two conserved segments is significantly similar to a segment of the presequence of yeast mitochondrial elongation factor EF-Tu. These results suggest that the homologous segments are important for the proteins that are synthesized in the cytosol to be transported into the mitochondrial matrix.

Amino Acid Sequence↗
PubMed1984

Complete amino acid sequence of Scytalidium lignicolum acid protease B.

The acid protease B (SLB) of Scytalidium lignicolum was reduced and carboxymethylated and then subjected to tryptic digestion. Five fragments were isolated and some of them were further digested with alpha-chymotrypsin, thermolysin, and dilute acetic acid. The sequence analysis of these fragments and the peptides by conventional methods established the complete amino acid sequence of SLB. The enzyme was composed of 204 amino acid residues with threonine and valine as its amino- and carboxyl-termini, respectively. Locations of three disulfide bridges were also established to be Cys47-126, Cys140-163, and Cys192-201 by enzymatic fragmentation of the denatured and unmodified SLB. Only a slight homology was found in the sequences of SLB and other acid proteases hitherto reported.

Amino Acid Sequence↗
PubMed1984

Echocardiographic features of bioprosthetic valve endocarditis.

Abnormal echocardiographic findings in seven cases of bioprosthetic valve endocarditis were confirmed in six at operation. The echocardiograms showed three cases with thickening and increased echo intensity (group 1) and four (group 2) in which vegetations were seen initially without either of the two features in group 1. Two patients in group 1 had vegetations, the causative organism being a streptococcus. Staphylococcus epidermidis was the causative organism in three of the four cases in group 2; in two of these rapidly growing vegetations were detected. The large vegetations obstructed the ostium of the bioprosthetic valve. Thus if vegetations are detected in cases in which staphylococci are the causative bacteria surgery should be performed as soon as possible. In patients who develop a fever after bioprosthetic valve replacement and especially in those with evident bacteraemia echocardiography should be repeated frequently so that lesions may be detected early.

Adult↗
PubMed1984

Mitral valve abnormalities in patients with right ventricular pressure overload. Analysis by real time cross sectional echocardiography.

Abnormalities of the mitral valve in patients with pulmonary stenosis, tetralogy of Fallot, and pulmonary hypertension with right ventricular pressure overload were studied by real time cross sectional echocardiography. Dislocation of the anterior and posterior mitral leaflets at the coaptation zone in systole was present in 16 of 46 cases: nine of 11 (82%) cases of pulmonary hypertension, four of 20 (20%) cases of tetralogy of Fallot, and three of 15 (20%) cases of pulmonary stenosis. The incidence was highest in patients with pulmonary hypertension. In eight of the 16 patients with mitral valve lesions, mitral regurgitation was seen on left ventriculograms or cross sectional Doppler echocardiograms. The dislocation was located near the posteromedial commissure of the anterior mitral leaflet in all cases. These findings are similar to the mitral valve abnormalities seen in patients with secundum atrial septal defect, and therefore may be due to a common cause. No relation could be found between the left ventricular deformity index and the incidence of dislocation of the mitral leaflets. Thus, the reason why this mitral valve abnormality occurs in conditions with right ventricular pressure overload could not be established.

Adolescent↗
PubMed1984

Clinical features of rheumatic heart disease in Bangladesh.

The clinical features of 205 cases of rheumatic heart disease in Bangladesh, including unique two-dimensional echocardiographic findings, were reported, and these were compared with those of 387 Japanese cases. The percentage of mitral stenosis (MS), aortic valvular diseases including both aortic stenosis and aortic regurgitation (A), mitral stenosis with aortic valvular diseases (MS + A) were almost the same between the two countries, but that of mitral regurgitation (MR) was higher, mitral stenosis and regurgitation (MSR) was lower in Bangladesh. The mean age of the patients with mitral valvular diseases was very young and the incidence of atrial fibrillation was very low in Bangladesh. Males predominated over females in MS (male/female = 1.2/1) and the incidence of pulmonary hypertension in MS was higher in Bangladesh. A two-dimensional echocardiographic examination showed that the rough zone was heavily involved in the rheumatic process with having a narrow mitral valve orifice while the clear zone was relatively spared and pliable in many patients with MS in Bangladesh. In MR, posterior mitral leaflets were shortened and made immobile by its submitral complex which were also thickened, fused and shortened, and these resulted in a gap or non-coaptation of the two leaflets in many patients.

Adolescent↗
PubMed1984

Clinical features of intracardiac thrombosis based on echocardiographic observation.

The nature of intracardiac thrombi were studied, which were the clinical underlying conditions, relation to systemic embolism, growth of thrombus and effect of anticoagulant therapy on the size of the thrombi, in 818 patients with mitral valve disease and 1000 patients with myocardial infarction by two-dimensional echocardiography. (1) Common underlying conditions were atrial fibrillation, enlarged left atrial cavity and predominance of mitral stenosis in cases with left atrial thrombi, and apical asynergy and low ejection fraction in cases with ventricular thrombi. The blood stasis should be the major factor in the formation of intracardiac thrombi. In a condition of blood stasis, dynamic intracavitary echoes which may represent erythrocyte aggregation were observed. (2) The incidence of systemic embolism in patients with thrombi was higher than that in patients without thrombi in cardiac disease. (3) The intracardiac thrombi were living. They grew and/or reduced their size spontaneously and sometimes became detached from the cardiac wall in the form of ball thrombi. (4) The effect of anticoagulant therapy on the regression of thrombi depends on its age.

Adult↗