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Biomedical subjects

Y Takagi

Publications and source records attributed to Y Takagi.

At least 667 records · Page 37Linked to original sources
PubMed1981

Nucleotide sequence of a ribosomal RNA gene intron from slime mold Physarum polycephalum.

The Physarum polycephalum 26S ribosomal RNA gene contains two intervening sequences (introns). The DNA sequence of one of these introns was analyzed together with that of its flanking regions (exons). In addition, the nucleotide sequence of the corresponding region of the reverse transcript of 26S rRNA was determined, and from comparisons of both sequences the precise location and size of the intron were determined. Our findings, when compared with those for Tetrahymena and Chlamydomonas rRNA gene introns, led to the conclusion that certain characteristics exist near the ends of these introns. (i) An exon ends in T at the exon/intron junction and an intron ends in G at the intron/exon junction in all cases. (ii) For each intron, direct repeats several nucleotides long are present 5 to approximately 30 nucleotides upstream from both the exon/intron and intron/exon junctions.

Base Sequence↗
PubMed1981

Purification and characterization of the Ca2+ plus Mg2+-dependent endodeoxyribonuclease from calf thymus chromatin.

Ca2+ plus Mg2+-dependent endodeoxyribonuclease was extracted from calf thymus chromatin and purified to a state free from contamination by other DNases. This DNase required both Ca2+ and Mg2+, or Mn2+ alone for its activity and the optimum pH for activity was at 6.5-7.5. No specificity for the 5'-base was observed. The molecular weight of the DNase was estimated to be about 25,000-30,000 by glycerol gradient centrifugation. Actin and antibody for pancreatic DNase (DNase I) did not inhibit the enzyme, whereas both strongly inhibited DNase I, suggesting that these two DNases are different enzymes.

Actins↗
PubMed1981

Cloning and characterization of ribosomal RNA gene of Physarum polycephalum.

As a first step in studies on the structure and expression of rRNA gene of Physarum polycephalum, the cloning of the gene in Escherichia coli with plasmid vector DNAs was performed and 8 different kinds of clones containing 26S, 19S, and 5.85 rRNA genes were obtained. Using these cloned fragments, the location of these rRNA genes was determined by the Southern hybridization and S1 mapping method. Cloning of rDNA fragments made it possible to analyze the fine structure of the rDNA.

Cloning, Molecular↗
PubMed1981

Molecular structures of packageable ColE1 hybrids and the generation of deletion mutants from one of the hybrids.

ColE1 derivatives carrying cohesive end sites of lambda phage genome (= cos lambda) can be packaged within lambda phage particles. The DNA structure of the prototype ColE1-cos lambda derivative named pKY2257 was studied because of its potential usefulness in various fields in molecular biology. pKY2257, which carries an intact galactose operon of E. coli, is a convenient replicon to detect Tn3 translocation. It was found that one of the PK2257::Tn3 derivatives, pKY2113, generated various small plasmids in E. coli. The molecular structures of some of these deletion mutants were compared with each other and with those of parental plasmid DNAs by heteroduplex analysis and restriction enzyme digestion. A possible mechanism, which seems to be unique to this kind of deletions, is discussed on the basis of the present results.

Bacteriocin Plasmids↗
PubMed1981

[Tricuspid valve motion and tricuspid valve ring size in normals and patients with atrial septal defect (author's transl)].

To investigate the normal configuration of the tricuspid valve and the normal size of the tricuspid valve ring, 17 normals, 20 patients with atrial septal defect, 4 patients with tricuspid valve prolapse, and 41 patients with various diseased conditions were studied by cross-sectional echocardiography. The tricuspid valve ring diameter in atrial septal defect was judged to be increased in comparison with that of normals. All the patients with tricuspid valve prolapse exhibited an excessive systolic ballooning of the leaflets toward the right atrium. However, a systolic ballooning of the leaflets alone was frequently observed in normals and many other conditions. Therefore, we conclude that cross-sectional echocardiography has some clinical limitations in the differential diagnosis between tricuspid valve prolapse and normals.

Adult↗
PubMed1981

[Cross-sectional and M-mode echocardiographic diagnosis of vegetative endocarditis in the right-sided heart (author's transl)].

M-mode and cross-sectional echocardiograms of 3 cases with vegetative endocarditis in the right-sided heart were reported. The location of vegetative lesions was the tricuspid valve in one, the parietal band of the right ventricle and chordae tendinae in one, and the pulmonary artery wall in the remaining patient. Ruptured chordae tendinae were observed in the patient with tricuspid valve vegetation. M-mode echocardiography detected vegetative lesions in all patients. However, the precise size and location of these lesions, and a complication of the destructive process were not evaluated by M-mode echocardiography. On the other hand, cross-sectional echocardiography not only documented the presence but also assessed the morphologic characteristics of the lesions, since this technique provides spatial orientation concerning moving structures. Furthermore, ruptured chordae tendineae in the patient with tricuspid valve vegetation was correctly estimated. However, the lesions should be differentiated from other conditions including a localized calcified lesion, abscess and thrombus. In conclusion, cross-sectional echocardiography in combination with M-mode echocardiography is recommended in diagnosing vegetative lesions in the right-sided heart.

Adolescent↗
PubMed1981

[Abnormal left ventricular configuration and contraction in patients with mitral stenosis: a cross-sectional echocardiographic study (author's transl)].

To assess left ventricular shape and contraction pattern under the condition of the narrowed mitral orifice, 41 patients with mitral stenosis were studied by cross-sectional and M-mode echocardiography. Abnormal left ventricular configuration and asynergy were observed in 23 patients (56%). The change in configuration persisted during the cardiac cycle and was mainly due to a straightening and abnormal motion of the interventricular septum. Furthermore, hypokinesis or akinesis of the posterior left ventricular wall contributed to the change of left ventricular shape. Consequently the left ventricular shape became from circular to half moon- or pear-like configuration. Of these 23 patients, 19 had a severe degree of subvalvular lesion, whereas such a lesion was noted in only 6 of the 18 patients with normal left ventricular shape and contraction pattern. It is considered that a rigid mitral complex immobilizes the posterior wall of the left ventricle in patients with mitral stenosis. In addition, tricuspid regurgitation, which was frequently observed in our patients, may play an important role in abnormal septal motion. This study showed that abnormal left ventricular shape and asynergy in the posterior wall are not rare in patients with mitral stenosis and are due to a rigid mitral complex and associated tricuspid regurgitation.

Echocardiography↗
PubMed1981

[Cross-sectional echocardiographic features of mobile left ventricular thrombi (author's transl)].

To assess the frequency, characteristics and relation to systemic embolization of mobile left ventricular thrombi, 154 patients with myocardial infarction were studied by cross-sectional echocardiography. In 5 (3%) a mobile left ventricular thrombus was detected. The electrocardiograms of all these patients showed anterior wall myocardial infarction pattern. One had cerebral embolism and two died suddenly. The cause of sudden death was not known, but it may be related to the presence of mobile left ventricular thrombi. In the remaining 149 patients, only 3 (2%) had cerebral or peripheral embolism. Mobile left ventricular thrombi was shown as rotating abnormal echoes arising from the left ventricular wall (infarcted area) by cross-sectional echocardiography. The size of thrombus was variable in each case. We concluded that cross-sectional echocardiography was useful in detecting mobile left ventricular thrombi, and that mobile left ventricular thrombi may be related to cerebral or peripheral emboli secondary to myocardial infraction.

Aged↗