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Biomedical subjects

Y Toyama

Publications and source records attributed to Y Toyama.

At least 145 records · Page 8Linked to original sources
PubMed1988

[An experimental study on the pathology and role of intervertebral discs in the progression and correction of scoliotic deformity].

This experimental study was designed to clarify the role of the intervertebral disc in the progression and correction of scoliosis. A total of 186 Wistar strain rats were used. Progressive scoliosis-like deformity was produced in tails by fixation of a given strain for a certain period. Changes in the intervertebral disc and epiphysis of one group with removal of the nucleus pulposus, and the other without removal were examined radiologically and pathohistologically. The results are as follows: 1) deformity originated from deviation of the nucleus pulposus toward the convex side and was followed by changes of the concave side, and led to deformities of the epiphysis and vertebral body; 2) on correction of the deformity, deviated nucleus pulposus and contracture of the concave side served as correction-inhibiting factors. The author's results indicate that intervertebral disc affecting the progression and correction of scoliosis are of great clinical significance.

Animals↗
PubMed1987

Periapical cemental dysplasia with multiple lesions.

3 cases of periapical cemental dysplasia with multiple lesions in both maxilla and mandible are reported. All 3 patients are middle-aged females with an average age of 47 years; histological examination of excised tissue revealed that the lesions were composed of fibrous connective tissue and cementum-like hard tissue. The location of the teeth affected were mainly in the premolar-molar regions. A subsequent literature survey of previously described Japanese cases of periapical cemental dysplasia disclosed a similar distribution pattern for the location of PCD lesions. This evidence indicates that the occurrence sites of lesions of periapical cemental dysplasia is predominantly in premolar-molar regions in Japan, contrary to the location of PCD in other ethnic groups.

Adult↗
PubMed1987

Retrovirus produced by a lymphoid cell line from an infant with acute lymphoblastic leukemia.

A lymphoid cell line CK-a was established from peripheral blood of an infant with acute lymphoblastic leukemia of non-T, non-B cell type with mediastinal tumor. The CK-a cells were positive for surface immunoglobulins, Epstein-Barr virus-specific nuclear antigen, HLA-DR and Leu 12 antigens, and negative for sheep erythrocyte-rosette-receptor, and Leu 1, 2, 3 and 4 antigens. Budding particles were detected in electron micrographs of ultrathin sections of the CK-a cells. In the culture media of CK-a cells, particles with a buoyant density of 1.16 g/ml and labeled with [3H]uridine and [35S]methionine but not with [3H]thymidine were found to carry reverse transcriptase activity which preferred Mg2+ to Mn2+. Enveloped particles of 80 to 120 nm in diameter were detected in the fractions at 1.16 g/ml by electron microscopy. Thus, the particles had properties compatible with a definition of Retroviridae, and were tentatively named CK virus (CKV). The genome size of CKV RNA determined by agarose-acrylamide composite gel electrophoresis was 6.1 +/- 0.2 kb. Immune electroblotting assay detected antibody reactive with a CKV protein with a molecular weight of 67,000 in the serum of the patient, but not in sera of an adult T cell leukemia patient and healthy controls. No syncytia were formed by mixed cultures of CK-a and XC cells.

Antibodies, Viral↗
PubMed1986

Effects of colcemid and taxol on microtubules and intermediate filaments in chick embryo fibroblasts.

Reports on how changes in microtubule (MT) distribution or polymerization affect the distribution of intermediate filaments (IFs) differ. Therefore, we have used cytoimmunofluorescence techniques and electron microscopy to systematically examine and compare the arrangements of MTs and IFs in cultures of chick embryo fibroblasts under the following conditions: at different times during the cell cycle, in the presence of Colcemid or of taxol, in the presence of both drugs in succession or simultaneously in varying ratios, and during recovery from treatment with Colcemid or taxol. We have found that depolymerization of MTs by 1 microM Colcemid resulted in the rapid formation of massive IF-cables, structures distinct from "collapsed IFs" or "juxtanuclear coils." Neither the rapid formation of IF-cables nor their dispersion during recovery required protein synthesis. Cells treated with 10 microM taxol rapidly formed MT-bundles, as well as aggregates of intertwining IFs, termed "IF-skeins." MT-bundles and IF-skeins displayed strikingly complementary distributions. This reciprocal distribution of packed MTs and IFs was also obvious in untreated anaphase and telophase cells. When 10 microM taxol and 1 microM Colcemid were applied simultaneously, the complementary distributions of MT-bundles and IF-skeins mimicked those in taxol alone. This ability of taxol to block Colcemid's effects was concentration dependent. Decreasing the taxol: Colcemid ratio allowed the depolymerization of MTs, which correlated with the formation of IF-cables.

Alkaloids↗
PubMed1985

Ultrastructural change of the thymocyte surface after treatment with specific antibodies. A rapid-freezing and deep-etching study.

A specific surface change of mouse thymocytes induced by treatment with anti-Thy-1 antibody was ultrastructurally demonstrated by a rapid-freezing and deep-etching technique. Round elevations, 30 nm in diameter, were found on the exoplasmic surface (ES) face of the cell membrane of BALB/c mouse thymocytes (expressing Thy-1.2 on the cell surface) after treatment with non-labelled monoclonal anti-Thy-1.2 antibody, whereas the ES face without the treatment gave a smooth appearance. Immunological studies indicated that the elevation was induced by the specific antigen-antibody reaction. Further, the elevation was demonstrated to be located at the site of antigen-antibody reaction by the results of the protein A-gold test. It was also supported by the fact that the elevations showed cluster formations under capping conditions. Accordingly, the elevations were assumed to be antibody molecules or antigen-antibody complexes.

Animals↗
PubMed1983

Taxol induces microtubule-rough endoplasmic reticulum complexes and microtubule-bundles in cultured chondroblasts.

Taxol induces a vast increase in the number of microtubules (MTs) in functional chondroblasts. The drug also induces a marked change in MT distribution. In control cultures, anti-tubulin stains long, fine, sinuous filaments radiating from a perinuclear center. In taxol-treated cells, anti-tubulin stains stubby, straight, chevron-like structures that assume a striking antipodal distribution. Such MT-bundles are relatively stable: they persist for over 48 h after removal of taxol, and even for 16-24 h in Colcemid. Many of these supernumerary MTs bind to, and align on, the cytoplasmic face of the rough endoplasmic reticulum (RER). In binding, the MTs displace the numerous ribosomes that normally stud the surface of the cisternae of the RER. The bound MTs form a remarkably uniform layer with center-to-center spacings of 40 nm. The attached parallel arrays of MTs achieve lengths of over 10 microns. These bound MTs not only dislodge ribosomes from the RER surface, but they also zip together adjacent ER complexes, forming tiers of two to eight cisternae. Numerous cytoplasmic bundles of hexagonally-ordered MTs are also induced. When closely aligned, the MTs assume a crystalline configuration with a six-fold symmetry, a central MT being surrounded by six equidistant MTs. A single cell can have over 100 MT-bundles and the number of MTs per bundles varies from 2-30. The forces aggregating cytoplasmic MT-bundles probably differ from those that bind MTs to the RER. Taxol also fragments the prominent Golgi complex that characterizes actively secreting chondroblasts. No obvious morphologic relationship has yet been detected between these induced MTs and other organelles such as intermediate-sized filaments, microfilaments, mitochondria, Golgi cisternae, or secretory vesicles.

Alkaloids↗
PubMed1983

Altered cell spreading in cytochalasin B: a possible role for intermediate filaments.

Trypsinized chicken embryo dermal fibroblasts plated in the presence of cytochalasin B (CB) quickly attached to the substrate and within 24 h obtained an arborized morphology. This morphology is the result of the pushing out of pseudopodial processes along the substrate from the round central cell body. There were no microfilament bundles in the processes of these cells plated in the presence of CB; however, the processes were packed with highly oriented, parallel-aligned intermediate filaments. Only a few scattered microtubules were seen in these processes. These results demonstrated that in CB, cells are capable of a form of movement, i.e., the extension of pseudopodial processes, without the presence of the microfilament structures usually associated with extensions of the cytoplasm and pseudopodial movements. We also found that arborization did not depend on fibronectin since cells plated in CB did not have fibronectin fibers associated with the processes. Chicken fibroblasts transformed with tsLA24A, a Rous sarcoma virus which is temperature sensitive for pp60src, formed arborized cells with properties similar to those of uninfected fibroblasts when plated in the presence of CB at the nonpermissive temperature (41 degrees C). At the permissive temperature for transformation (36 degrees C), the cells attached to the substrate but remained round. These round cells were not only deficient in microfilament bundles but also lacked the highly organized intermediate filaments found in the processes of the arborized cells at 41 degrees C. Although both microfilament bundles and the fibronectin matrix were decreased after transformation with Rous sarcoma virus, neither was involved in the formation of processes in normal cells plated in CB. Therefore, the inability of the transformed cells to form or maintain processes in CB must be the result of another structural alteration in the transformed cells, such as that of the intermediate filaments.

Actins↗
PubMed1982

Further observations on the Sertoli cell junctions of the mouse testis after metal contract freeze-fracture, and comparisons with cellular junctions of other epithelial cells.

Using a metal contact freezing methods, the junctional complexes of Sertoli cells and other epithelial cells (intestine, liver, and epididymis) in the mouse were studied by freeze-fracture in unfixed and in aldehyde-fixed specimens. The tight junctions of the Sertoli cells without fixation consists of discrete rows of particles located preferentially on the E face. Continuous furrows with or without tight-junctional particles are found on both fractured faces. The majority of the tight-junctional particles of th Sertoli cells are situated at one side of the furrow rather than in the center. The "aisle" configuration of the gap junction is seen in developing Sertoli cells prepared without fixation. Tight junctions of epithelial cells other than Sertoli cells consists of discrete rows of particles on the E face and furrows on the P face when prepared without fixation. The tight and gap junctions of the Sertoli cells are not affected by fixation, but the tight junctions of other types of epithelial cells are effected as previously suggested. A distribution pattern of the gap-junctional particles of the Sertoli cells and of other cells shows a pleomorphism. Changes in gap junctions produced by fixation could not be detected clearly. Characteristics of the Sertoli-cell junctions are discussed. Desmosomes between the intestinal epithelial cells without fixation are presented.

Animals↗
PubMed1982

Effects of taxol and Colcemid on myofibrillogenesis.

To determine the relationship between thin filaments, Z-bands, microtubules, intermediate filaments (IFs), T-tubules, and sarcoplasmic reticulum (SR) during myofibrillogenesis, myotubes were selectively depleted of their myofibrils with 12-tetradecanoylphorbol 13-acetate (TPA) and then were allowed to regenerate in (i) normal medium, (ii) taxol, and (iii) Colcemid. Myofibrils assembled in normal medium formed typical A-, I-, Z-, M-, and H-bands and associated IFs, T-tubules, and SR. Myofibrils assembled in taxol formed "A-bands" of aligned thick filaments interdigitating with long microtubules and "I-bands" consisting only of microtubules. These unprecedented sarcomeres lacked thin filaments, Z-bands, and associated IFs and SR. "Solitary A-bands," consisting exclusively of laterally aligned bipolar thick filaments 1.6 microM in length without either thin filaments or microtubules, were observed. Myofibrils assembled in Colcemid formed all myofibrillar components in the absence of microtubules but these did not achieve rigorous lateral alignment. Colcemid and taxol induced the formation of patchy Z-bands that invariably served as insertion sites for thin filaments, irrespective of the presence or absence of adjacent thick filaments. Z-bands may function as actin-organizing centers for each sarcomere.

Actins↗
PubMed1982

The response of chicken embryo dermal fibroblasts to cytochalasin B is altered by Rous sarcoma virus-induced cell transformation.

The drug cytochalasin B (CB), which disrupts the cellular microfilament network, allows the identification of as yet unclassified structural differences between normal and Rous sarcoma virus-transformed chicken embryo fibroblasts. When exposed to CB, normal chick fibroblasts attain an arborized or dendritic morphology. This results as the cytoplasm collapses upon the remaining structural and adhesive components of the cell. Rous sarcoma virus-transformed cells did not form or maintain these dendritic-like processes in the presence of CB and, as a result, rounded up but still remained attached to the substrate. With a temperature-sensitive mutant of Rous sarcoma virus, LA24A, it was possible to show that these effects are completely reversible and dependent on the expression of pp60src. The cytoskeleton in these CB-treated cells was examined by both immunofluorescence and electron microscopy. After exposure to CB, the microfilaments were found to be disrupted similarly throughout both the transformed and the nontransformed cells. In the nontransformed cells arborized by exposure to CB, the extended processes were found to contain intermediate filaments in an unusually high concentration and degree of organization. The distribution of these filaments in the central body of the arborized cells was random. This lower concentration and random distribution was similar to that seen throughout the transformed cells rounded up by exposure to CB. The failure of these transformed cells to arborize in CB indicates that the structural component(s) which is necessary for the formation or maintenance or both of the arborized state is altered by the expression of pp60src.

Animals↗