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Biomedical subjects

T Mikawa

Publications and source records attributed to T Mikawa.

At least 109 records · Page 6Linked to original sources
PubMed1983

Changes in myosin isozymes during development of chicken gizzard muscle.

The distribution of myosin isozymes in embryonic and adult chicken gizzard muscle were examined by electrophoresis in a non-denaturing gel system (pyrophosphate acrylamide gel electrophoresis), and both light and heavy chains of embryonic and adult myosin isozymes were compared. In pyrophosphate acrylamide gel electrophoresis, there were three isozyme components in embryonic gizzard myosin, but only one isozyme in adult gizzard myosin. The mobility of the fastest migrating embryonic isozyme was similar to that of the adult isozyme. The three embryonic isozymes differ from each other in the light chain distribution. Two of them contain an embryo-specific myosin light chain, which is characterized by its molecular weight and isoelectric point, whereas the other embryonic myosin isozyme contained the same light chains as the adult myosin. The pattern of peptide fragments of embryonic heavy chain produced by digestion with alpha-chymotrypsin in the presence of SDS was not distinguishable from that of adult myosin heavy chain. Thus there are myosin isozymes specific to embryonic gizzard muscle which exhibit embryo-specific light chain compositions, but are similar to adult gizzard myosin in their heavy chain structure.

Animals↗
PubMed1983

Separation and identification of Drosophila myosin light chains.

Myosin was extracted from the larvae and adult flies of Drosophila melanogaster, and purified by column chromatography in the presence of KI. Myosin light chains were separated from heavy chains by column chromatography after treatment of the myosin with urea, and they were identified by 2D-gel electrophoresis. Tubular muscles and fibrillar muscles have different light chains. Lt1 (Mw = 31,000), Lt2 (Mw = 30,000), Lt2' (Mw = 30,000), and Lt3 (Mw = 20,000) exist in the tubular myosin of both larvae and adult flies; Lf1 (Mw = 34,000), Lf2 (Mw = 30,000), Lf2' (Mw = 30,000), and Lf3 (Mw = 20,000) exist in the fibrillar myosin. Polyacrylamide gel electrophoresis of myosin under nondissociating conditions revealed that there was one major myosin isozyme in each type of adult muscle, and the re-electrophoresis of each isozyme on SDS gel confirmed our identification of the light chains.

Animals↗
PubMed1983

[Mode of production of the splitting of the second heart sound in post-extrasystolic beats].

The changes in left and right ventricular systolic time intervals (LV- and RVSTIs) and split interval of the second heart sound (IIA-IIP interval) associated with post-extrasystolic potentiation were studied in 48 patients including 37 without a significant intracardiac shunt or valvular regurgitation or pulmonary hypertension, 7 with aortic stenosis (AS) and 4 with hypertrophic obstructive cardiomyopathy (HOCM). In 19 out of 37 patients mentioned above, LV- and RVSTIs were measured from carotid pulse and pulmonary arterial pulse waves, and IIA-IIP interval of post-extrasystolic beat with a compensatory pause was compared to that of the preceding sinus beat. In the other 29 patients including AS and HOCM, LVSTI, total electromechanical systole of the right ventricle (Q-IIP) and IIA-IIP interval were compared. There was no significant difference in the coupling index [(compensatory pause-coupling interval)/preceding RR interval X 100(%)] among three groups. The following results were obtained: In all patients without HOCM, post-extrasystolic beats showed wider IIA-IIP interval than the control beats independent upon the diseased entity and severity of cardiac function. In pts with HOCM, a IIA-IIP interval was shortened in post-extrasystolic beats. A IIA-IIP interval at post-extrasystolic beats was prolonged in proportion to the augmentation of coupling index. However, this finding was no longer observed in cases with the coupling index of more than 80%. LVSTI: In patients without HOCM, almost no change or prolongation of left ventricular ejection time (LVET) and shortening of left ventricular preejection period (LPEP) were observed in post-extrasystolic beats. The degree of changes in LVET and LPEP was greater in patients with the abnormal left-sided PEP/ET than in patients with the normal PEP/ET. The degree of changes in LPEP was always greater than that in LVET, therefore, total electromechanical systole of the left ventricle (Q-IIA) was shortened in all patients. In HOCM, a marked prolongation of LVET and a shortening of LPEP were observed. The degree of changes in LVET was greater than that in LPEP, therefore, Q-IIA was prolonged in all patients. RVSTI: Prolongation of right ventricular ejection time (RVET) and shortening of right ventricular preejection period (RPEP) were observed in all patients in post-extrasystolic beats. The degree of changes in RVET and RPEP was increased in patients with the increased right-sided PEP/ET. The degree of changes in RVET was greater than or equal to that in LPEP, therefore, Q-IIP showed slight prolongation or no change.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

Localization of Z-protein in isolated Z-disk sheets of chicken leg muscle.

Immunoblotting studies with antisera against Z-protein, desmin, and alpha-actinin showed that Z-protein is clearly distinguishable from desmin and alpha-actinin. Z-protein is not a proteolytic product of another protein but is an intrinsic component of chicken breast muscle myofibrils. In these experiments, an SDS extract of intact muscle was first electrophoresed in a polyacrylamide gel, and then proteins were transferred to a nitrocellulose paper sheet. Detection of each protein on the sheet was made possible by the application of the indirect immunofluorescence technique with the respective antiserum. Immunofluorescence microscope studies using these antisera revealed that Z-protein has the same distribution as alpha-actinin in isolated Z-disk sheets. Anti-Z-protein antiserum and anti-alpha-actinin antiserum stained the interior of Z-disks. On the other hand, antiserum against desmin stained the periphery of Z-disks in isolated Z-disk sheets.

Actinin↗
PubMed1982

Changes in myosin isozymes during development of chicken breast muscle.

The patterns of myosin isozymes in embryonic and adult chicken pectoralis muscle were examined by electrophoresis in a non-denaturing gel system (pyrophosphate acrylamide gel electrophoresis), and both light chains and heavy chains of embryonic and adult myosin isozymes were compared. In pyrophosphate acrylamide gel electrophoresis, the predominant isozyme component in embryonic pectoralis myosin could be clearly distinguished from adult myosin isozymes. SDS-polyacrylamide gel electrophoresis indicated that the light chain composition of embryonic myosin was also different from that of adult myosin. The pattern of peptide fragments produced by myosin digestion with a-chymotrypsin differed significantly between embryonic and adult skeletal myosin. These results suggest that myosin in the embryonic pectoralis muscle is different in both light and heavy chain composition from myosin in the same adult tissue.

Animals↗
PubMed1981

Gene expression of myofibrillar proteins in single muscle fibers of adult chicken: micro two dimensional gel electrophoretic analysis.

Using a micro two dimensional gel electrophoretic system and silver stain method, we examined the isoform patterns of myofibrillar proteins in single muscle fibers of adult chicken. Several isoforms of myosin light chains, tropomyosin, troponin T, troponin I, and troponin C were identified. Analysis of pectoral, anterior latissimus dorsi, sartorius and soleus muscle revealed that single fibers contained either fast or slow form of each of the troponin subunits, indicating that troponin exists as a 'homocomplex.' The form of troponin in a given cell was associated with that of myosin light chains. The form of tropomyosin, however, was not associated with those of myosin light chains and troponin, but was tissue specific. Overall, we found four combinations of isoforms of myosin light chains, troponin subunits and tropomyosin subunits. In adult dystrophic chicken the isoform patterns of tropomyosin and troponin T in single fibers of pectoral muscle markedly deviated from the normal patterns.

Animals↗
PubMed1979

'Freezing' of the calcium-regulated structures of gizzard thin filaments by glutaraldehyde.

Reconstituted thin filaments (the actin-tropomyosin-leiotonin complex) of chicken gizzard were cross-linked with glutaraldehyde either in the presence or absence of Ca2+. The ability of resultant thin filaments to activate myosin ATPase was 'frozen' in the activated or inactivated state, respectively. This result clearly indicates the existence of actin-linked regulation in smooth muscle.

Actins↗
PubMed1979

Crystallization and preliminary crystallographic data of chicken gizzard G-actin . DNase I complex and Physarum G-actin . DNase I complex.

Smooth muscle G-actin from chicken gizzard and Physarum plasmodium G-actin both interact with DNase I and form 1 : 1 complexes. These complexes were crystallized by using polyethylene glycol 6000 as a precipitant. Both crystals belong to the same orthorhombic space group P2(1)2(1)2(1). The cell dimensions of chicken gizzard G-actin.DNase I complex are a=42.00 +/- 0.07 A, b=225.3 +/- 0.4 A, and c=77.4 +/- 0.1 A, while those of Physarum G-actin.DNase I complex are a=42 A, b=221 A, and c=77 A.

Actins↗
PubMed1977

Ca2+ regulation in vascular smooth muscle.

Regulation of aorta smooth muscle contraction by Ca ion requires the collaboration of the 80,000 dalton factor and tropomyosin. A method for preparing pure actin from aorta smooth muscle is described.

Actins↗