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Y Sugi

Publications and source records attributed to Y Sugi.

33 records · Page 2Linked to original sources
PubMed1992

Onset of expression and regional deposition of alpha-smooth and sarcomeric actin during avian heart development.

The sequential appearance of mRNAs for smooth, cardiac, and skeletal alpha-actin has been described during development of the chicken heart (Ruzicka, D.L., and R.J. Schwartz 1988 J. Cell Biol., 107:2575-2586). To assess whether this reflects the deposition of corresponding isoproteins, we have immunocytochemically localized smooth and sarcomeric (cardiac and skeletal) alpha-actin in Hamburger-Hamilton (H-H) stage 7-18 embryos using monoclonal antibodies. Within the developing embryo at stage 9-, smooth muscle alpha-actin was exclusively detected in the developing heart, upon fusion of the endocardial tubes; sarcomeric alpha-actin was observed later (stage 9). By the onset of contraction at stage 10+, intense immunostaining of both smooth and sarcomeric isoproteins was observed in the ventricle; at this time smooth muscle alpha-actin was also detected in splanchnic mesoderm of the pre-vitelline area, in a cellular layer adjacent to the only embryonic cells that exhibited factor VIII (von Willebrand factor) antigens. Double immunostaining of the myocardium at stage 11, at which time striations were first detected, revealed the co-existence of smooth and sarcomeric actin in developing sarcomeres. Intense expression of sarcomeric actin continued in the heart after stage 11, whereas smooth muscle alpha-actin was down-regulated in the ventricle and became regionalized to the inflow and outflow tracts. As expected, smooth muscle alpha-actin was detected around intra- and extra-embryonic vascular structures at later developmental stages, while sarcomeric actin was observed in somites.

Actins↗
PubMed1992

[Studies on the erythrocyte membrane skeleton in a patient with chorea-acanthocytosis--theoretical speculation on the mechanism of neurological involvement].

Patients with chorea-acanthocytosis exhibit symptoms of self-biting, choreic movement, and acanthocytosis, but not dementia. The mechanism of choreic movements is still unknown. In order to clarify the etiologic mechanism underlying these movements, we evaluated the erythrocyte membrane in one patient with chorea-acanthocytosis. A 35-year-old female was admitted to Saitama Medical School Hospital because of involuntary movements. She was alert, well-oriented, and had no gross memory defects. She had slurred speech, choreic movements and lip biting. Laboratory examination showed acanthocytes in her peripheral red blood cells, normal serum lipid values, and caudate atrophy on her brain CT scan. In analyzing the acanthocytes, we initially evaluated the size of the acanthocyte population by incubating her red blood cells with plasma. The cell population approximately doubled after 2 hours incubation. Next we examined the protein composition of erythrocyte ghost by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). There was no significant difference between the patient's erythrocyte ghosts and those of a control. Then we investigated morphological changes in the patient's erythrocyte by scanning and transmission electron microscopy (SEM and TEM). SEM showed the typical acanthocyte shape. The quick-freeze, freeze-substitution method confirmed that the routine TEM section was not artifactual, and was in fact in accurate reflection of the actual features of acanthocytes. TEM of the sections prepared from erythrocyte ghosts demonstrated that spectrin tended to be accumulated in the thorn region. Furthermore, TEM of quick-freeze, deep-etched replica of the ghost revealed more clearly a spectrin network densely packed on the inner hydrophilic surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Acanthocytes↗
PubMed1991

Cytoskeletal filaments in embryonic chick myocardial cells as revealed by the quick-freeze deep-etch method combined with immunocytochemistry.

The three-dimensional organization of cytoskeletal filaments associated with the myofibrils and sarcolemma of the myocardial cells of early chick embryos was studied by the rapid-freeze deep-etch method combined with immunocytochemistry. In the endoplasmic region of saponin-treated myocardial cells, 12-14 nm filaments formed a loose network surrounding nascent myofibrils. These 12-14 nm filaments attached to the myofibrils and some of them converged into Z disc regions. In the non-junctional cytocortical region thinner 8-11 nm filaments composed a dense network just beneath the sarcolemma. In myofibril terminating regions at the sarcolemma, i.e., the fascia adherens, 3-5 nm cross-bridges were observed among the thin filaments. In Triton-permeabilized and myosin subfragment 1 (S1)- treated samples, subsarcolemmal 8-11 nm filaments proved to be S1-decorated actin filaments under which there was a loose network of S1-undecorated filaments. Subsarcolemmal S1-decorated actin filaments had mixed polarity and attached to the sarcolemma at one end. A loose network of S1-undecorated filaments among myofibrils in the endoplasmic region was revealed to consist of desmin-containing intermediate filaments after immuno-gold staining for desmin. These networks connecting myofibrils with sarcolemma were assumed to play an important role in integrating and transmitting the contractile force of individual myofibrils within early embryonic myocardial cells.

Actin Cytoskeleton↗
PubMed1989

Visualization and identification of cytoskeletal filaments in embryonic chick heart by the quick-freeze deep-etch method combined with immunocytochemistry.

Cytoskeletal filaments in myocardial cells of chick embryo (stage 18-20, day 3) were studied by immunocytochemical and rapid-freeze deep-etch methods. A three-dimensional network of cytoplasmic filaments surrounding nascent myofibrils was visualized in saponin-treated myocardial cells. The major part of the network was composed of 12 to 14 nm filaments in platinum replicas. To identify the filaments, the myocardial cells were permeabilized with Triton X-100 and treated with myosin subfragment-1 (S1) for actin or immunogold-labeled antibody for desmin. A large number of filaments in myofibrils and a few cytoplasmic filaments were decorated with S1. A loose network surrounding the myofibrils was not decorated with S1 but with gold particles. This finding means that the majority of filaments occupying the interfibrillar space were desmin-containing filaments.

Actin Cytoskeleton↗
PubMed1986

Freeze-fracture studies of the sinoatrial and atrioventricular nodes of the caprine heart, with special reference to the nexus.

The caprine sinoatrial node (SAN) and atrioventricular node (AVN) were studied by freeze-fracture techniques, and their nexus or gap junction structure were compared with that of ordinary atrial and ventricular muscle cells. The general features of the nexus in both the SAN and AVN were essentially identical. Approximately two-thirds of the nexuses observed in the nodal cells consisted of typical macular arrangements of nexal particles, and the remaining third, of atypical configurations of either circular arrangements or linear arrays of particles in continuity with the macular nexuses. Such atypical nexuses were never observed in the ordinary adult myocardial cells. Quantitative analysis revealed that all of the nexuses in the nodal cells measured, were less than 0.1 micron 2, whereas the majority of the nexuses in ordinary myocardial cells (64% in the atrium and 76% in the ventricle) were larger than 0.1 micron 2. No significant differences in diameter and center-to-center distance of nexal particle were found between the nodal cells and ordinary myocardial cells.

Animals↗
PubMed1986

Ultrastructural quantitative characterisation of sinus and atrioventricular nodal cells in the developing caprine heart compared with ordinary atrial and ventricular myocardial cells.

Cellular growth and changes in subcellular components as well as in intercellular junction structure were investigated quantitatively in sinus and atrioventricular nodes in comparison with right atrial and left ventricular myocardial cells of the goat heart in fetuses aged 6, 8, 10, 12, 14, 16 and 18 gestational weeks, young animals aged 1 and 3 postnatal weeks, and adults. At the earliest stage examined (sixth gestational week) no clear difference was recognised, in the patterns of star diagrams representing cellular characteristics, between nodal cells and ordinary cardiac muscle cells, except for a larger number of myofibrils in the ordinary cells. Atrial specific granules also appeared in the atrial cells at this stage. In general, initial signs of differentiation in ordinary cardiac muscle cells were detected at the sixteenth gestational week when transverse tubule formation occurred in the ventricular muscle cells. Throughout the developmental period, no appreciable alterations in the ultrastructural features were found in the sinus nodal cells whereas the atrioventricular nodal cells revealed slight changes at the later fetal and adult stages.

Animals↗
PubMed1985

Electron-microscopic study of the collagen fibrils of the rat tail tendon as revealed by freeze-fracture and freeze-etching techniques.

The ultrastructure of the collagen of rat tail tendon was investigated by the freeze-fracture technique. Collagen fibers were pretreated with the digestive enzymes, alpha-amylase, elastase and collagenase to remove matrix substances. Some of the samples were etched for 20 min. Fibrils had an average diameter of 318 +/- 12 nm and a banded structure with a mean periodicity of 64.2 +/- 0.9 mm; the banding was most marked in alpha-amylase/elastase-treated specimens, although the periodicity was independent of pretreatment. Microfibrils were well-displayed following alpha-amylase/elastase and collagenase pretreatments. A difference in the diameters of microfibrils was, however, observed between etched specimens (8.3 +/- 0.3 nm) and those prepared by other experimental methods (11.4 +/- 0.5 nm). In replicas of collagenase-treated and etched specimens, the interconnecting filaments in the interfibrillar region formed a network that was continuous with the microfibrils of collagen fibrils. The diameter of the interconnecting filaments was the same as that of microfibrils. Microfibrillar bundles were observed in the interfibrillar region.

Amylases↗
PubMed1983

Calcium detection in secretion granules of avian oviduct by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX).

Secretion granules in the shell gland, isthmus, and albumin-secreting region of the hen oviduct were analyzed with WET-scanning electron microscopy (SEM) and EDX, a combination of wide-angle backscattered electron detector (BED) and energy-dispersive X-ray microanalyzer (EDX). Glutaraldehyde-fixed but unhydrated, unstained, and uncoated samples were analyzed; Ca was localized in all secretion granules in all three sections of the hen oviduct studied.

Animals↗