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Biomedical subjects

M Yamato

Publications and source records attributed to M Yamato.

At least 73 records · Page 4Linked to original sources
PubMed1997

Synthesis and antitumor activity of fused quinoline derivatives. IV. Novel 11-aminoindolo[3,2-b]quinolines.

Indolo[3,2-b]quinoline derivatives (1) having various amine moieties were prepared and their antitumor activities against P388 leukemia in mice were evaluated, for the purpose of gaining an insight into the role of the amine moiety in the antitumor activity and searching for an effective amine moiety. Introduction of a methylene group between the phenyl group and amino or methanesulfonamido group resulted in decrease or loss of activity.

Animals↗
PubMed1996

Intertrabecular pattern of tumors metastatic to bone.

BACKGROUND: The prevalence of radiologically invisible metastatic tumors to bone is not known. To clarify this, the authors examined histologic sections, radiographs, bone scans, and magnetic resonance (MR) images of autopsied patients with bone metastases. METHODS: Complete slices of the vertebral column, including C3-S1, were obtained from 52 cadavers with metastatic tumors to the spine. Macroscopic and histologic features were compared with postmortem roentgenographs (52 patients), bone scans with 99mTc-labelled methylene diphosphonate (17 patients), and MR images (4 patients). Morphologic patterns were classified into intertrabecular, osteoblastic, osteolytic, mixed, small lesion, and compression fracture. RESULTS: Metastatic lesions were found in 734 of the 1194 vertebral bodies. The lesions were intertrabecular in 255 vertebrae, osteoblastic in 185, osteolytic in 114, mixed in 70, small lesion in 83, and compression fracture in 27. Postmortem radiographs demonstrated lesions in 367 (50%) of the 734 vertebrae, bone scans in 103 (34.7%) of the 297 vertebrae examined, and MR images in all 42 (100%) vertebral bodies imaged. Lesions showing an intertrabecular pattern were detected in only 7.1% of the radiographs and 4.5% of the bone scans. CONCLUSIONS: Radiographs and bone scans often fail to show metastatic lesions, especially those with an intertrabecular pattern. The intertrabecular pattern is a unique histologic form that is difficult to detect on radiographs and bone scans.

Adult↗
PubMed1996

Retardation of phenotypic transition of rabbit arterial smooth muscle cells in three-dimensional primary culture.

Three-dimensional gel culture systems represent conditions that mimic the differentiated state of mesenchymal cells in vivo. We examined gel contraction, cell growth, and phenotypic modulation of rabbit arterial SMC in three-dimensional gel culture. The gel contraction rate was dependent on the collagen type; that is, the contraction by freshly isolated SMC was faster and more pronounced in type I collagen than in type III collagen. In contrast, the phenotypic modulation of SMC was independent of collagen type. The major portion of cells in both type I and III collagens with growth factors underwent transition from a contractile (G0 phase) to a synthetic phenotype (G1B phase), but this transition was clearly delayed compared with that on collagens. The cells had hardly begun DNA synthesis in either collagen type and failed to proliferate even after 10 days of culture. These results indicate that collagen type is important in gel contraction by vascular SMC, while the organization of collagen fibrils (two-dimensional vs three-dimensional) is more critical in the phenotypic transition and proliferation of these cells. However, the more specific organization of extracellular matrix than the collagen gel culture system may be necessary to maintain the contractile phenotype of SMC.

Animals↗
PubMed1996

Trabecular trauma of the talus and medial malleolus concurrent with lateral collateral ligamentous injuries of the ankle: evaluation with MR imaging.

OBJECTIVE: The objective of this study was to elucidate the relationship between lateral collateral ligamentous injuries of the ankle (ankle sprain) and bone bruise (trabecular trauma) of the talus and/or malleoli in the patients with twisting injuries of the ankle. DESIGN: Magnetic resonance studies of the ankle were retrospectively reviewed, focusing on the presence or absence of lateral collateral ligamentous injuries and the location of bone bruise in the talus and/or malleoli. PATIENTS: Thirty-five patients with acute twisting injuries of the ankle were studied. RESULTS AND CONCLUSION: Four patterns of bone bruise were found in 14 patients: (1) bone bruise in the talar dome equivalent to osteochondral fracture in two patients, (2) bone bruise in the posteromedial aspect of the talus and the medial malleolus singly or in combination in four, (3) bone bruise in the anteromedial aspect of the talus in six, and (4) bone bruise with a combination of the second and third patterns in two. The second pattern was associated with tear of the anterior talofibular (ATAF) ligament in all patients and injury of the calcaneofibular (CF) ligament in one out of four. The third and fourth patterns were associated with tears of both ATAF and CF ligaments in all patients. The identification of bone bruise was of value in indicating lateral collateral ligamentous injuries.

Adolescent↗
PubMed1996

Fragile bone syndrome associated with craniognathic fibro-osseous lesions and abnormal modeling of the tubular bones: report of two cases and review of the literature.

OBJECTIVE: To report examples of disorders characterized by bone fragility, calvarial and/or gnathic fibro-osseous lesions, and metadiaphyseal undermodeling of the tubular bones. DESIGN: The clinical, radiological, and pathological features of two patients are described and the literature reviewed. PATIENTS: The patients comprised a 10-year-old boy and a 48-year-old woman. The former exhibited multiple fractures starting in early childhood and calvarial masses which developed in late childhood; the latter showed a mandibular mass. RESULTS: Calvarial doughnut lesions, osteopenia with coarse bony trabeculae, and undermodeling of the lower limbs were radiologically demonstrated in the first patient, while multiple sclerotic foci in the maxilla and mandible, spontaneous bowing of the right femur, and minimal undermodeling of the tibiae were demonstrated in the second. Bone biopsy of the iliac crest in the first patient revealed histologically normal bony trabeculae. Bone histomorphometry suggested an increased osteoid surface. Osteoid volume was also slightly increased. The pathological findings of the mass in the jaw in the latter patient were consistent with it being a fibro-osseous lesion. The literature review revealed several patients whose features overlapped with those of our patients. CONCLUSION: These patients may represent a group of fragile bone syndromes which differ from osteogenesis imperfecta.

Bone Diseases, Developmental↗
PubMed1996

Magnetic resonance imaging of clival marrow in patients with anorexia nervosa.

Hematological abnormalities, commonly associated with anorexia nervosa (AN) patients, are thought to be the results of serous atrophy in the bone marrow. Magnetic resonance imaging (MRI) has been utilized to ascertain T1 and T2 prolongation of marrow intensity in the lumbar spine, pelvis and proximal femora. The results correlate well with the severity of hematological abnormalities, and body mass index. More importantly, the propensity for peripheral marrow involvement of T2 prolongation contrasts with the axial involvement in other marrow disorders. MRI undertaken in patients with AN to exclude hypothalamic tumor showed that the clival marrow was equivalent to the peripheral marrow. The signal pattern of clival marrow on sagittal T1 weighted MR images was evaluated in four teenage female patients with AN complicated by hematological abnormalities. Although the clival marrow intensity should be uniformly high in teenagers, three patients, two with pancytopenia and one with leukopenia and anemia, exhibited homogeneous low intensity. One patient who had leukopenia only and the highest body mass index, showed inhomogeneous low intensity. The signal changes returned to normal in all patients but one, who died before examination after 6-11 months, at which time the others had almost recovered their original weight and normal hemogram. T1 prolongation in the clival marrow represents bone marrow dysfunction and the inhomogeneity of the signal change may imply relative preservation of hematopoiesis and body fat composition. Lack of knowledge of this phenomenon may lead to diagnostic confusion with other marrow disorders on cranial MRI.

Adolescent↗
PubMed1995

Identification of integrins involved in cell adhesion to native and denatured type I collagens and the phenotypic transition of rabbit arterial smooth muscle cells.

Rabbit smooth muscle cells (SMC) in primary culture attached to and started proliferating on native and heat-denatured type I collagens, although the amount of cell attachment to denatured collagen was significantly lower. The cells adhered poorly and were unable to grow on commercial gelatin. In contrast, synthetic SMC in secondary culture could adhere to gelatin and grew as well on gelatin as on native type I collagen. The SMC in the contractile state adhered to native type I collagen through the alpha 1 beta 1 and alpha 3 beta 1 integrins. The cells in the intermediate phenotype also adhered to the substrate through the alpha 1 beta 1 and alpha 3 beta 1 integrins, but the relative amount of alpha 3 integrin decreased. The initial adhesion of cells in secondary culture to native type I collagen was mediated only by the alpha 1 beta 1 integrin. The cell-binding sequences did not contain DGEA (Asp-Gly-Glu-Ala) or RGD (Arg-Gly-Asp). In contrast, cell adhesion to heat-denatured type I collagen was mediated only by the alpha 1 beta 1 integrin in the contractile state and by the alpha 1 beta 1, alpha 2 beta 1, and alpha 3 beta 1 integrins in the synthetic state. In heat-denatured type I collagen, the sequences DGEA and RGD served as a recognition site for the alpha 2 beta 1 and alpha 3 beta 1 integrins. Our results suggest that rabbit SMC can recognize the native and denatured type I collagens through interactions with the triple helix-binding receptors and alpha chain-binding receptors and that the expression pattern of integrins changes in conjunction with the phenotypic properties of vascular SMC.

Amino Acid Sequence↗
PubMed1995

Immunochemical analysis and localisation of a cell wall antigen of Streptococcus rattus with a specific monoclonal antibody.

A monoclonal antibody specific to a cell wall antigen of Streptococcus rattus (S. rattus) was prepared after cell fusion of mouse myeloma cells to the spleen cells of mice immunized with whole cells of strain FA1. The monoclonal antibody reacted with a crude and purified polysaccharide antigen of S. rattus in precipitin reactions as well as in a solid phase enzyme assay (EIA). It also reacted in the EIA with whole cells of S. rattus strains, but did not react with any other species of the mutans group or of other oral and streptococcal species. Moreover, among many haptenic sugars and their derivatives tested, D-galactosamine and D-glucosamine strongly inhibited the reaction in a competitive enzyme immunoassay using the purified antigen and whole cells, indicating that the type-specific antigenic determinant of the organism has a structure similar to the amino group of the sugar molecules. Furthermore, immunoelectron microscopy revealed that the antigen epitopes formed an irregular fibrous structure over the entire surface of individual cells.

Animals↗
PubMed1995

Condensation of collagen fibrils to the direct vicinity of fibroblasts as a cause of gel contraction.

Fibroblasts were cultured within FITC-prelabeled type I collagen. Cells initially round in shape protruded processes, and began to collect the fibrils into their vicinity. Repeated protrusion and withdrawal of cell processes was observed. Consequently, condensed fluorescence was observed on the elongated bipolar cells stained with rhodamine-phalloidin. Concomitantly with these events, the gel began to contract in overall size, with an increase of fluorescence intensity. Scanning electron micrographs of the contracted gel showed a disproportional distribution of collagen fibrils: a highly condensed region surrounding cell bodies and a moderately condensed region. A major portion of condensed fibrils may have been derived from reconstituted collagen fibrils, since fibroblasts within collagen gel synthesized little collagen. When the gel adhered to glass tightly, so that overall contraction was prevented, the fluorescence in a range of scores of micrometers from the cells disappeared owing to depletion of fibrils by the cells. The combined spaces with null fluorescence in total under repressed contraction corresponded well to the reduction in volume due to gel contraction. It seems likely that the fibril condensation onto the cells causes the overall gel contraction.

Actins↗
PubMed1995

Chromatographic study of spirosin by use of monoclonal antibodies to spirosin of Yersinia enterocolitica.

Two monoclonal antibodies (MAbs) reacting with spirosins from Enterobacteriaceae were obtained in a course of screening MAbs to spirosin from Yersinia enterocolitica SYT-11-72 (YE72). The antibodies were designated MAbs-S44 and S50. They were IgG2b and IgG2a, respectively, both with kappa light chains. On Western blotting after limited proteolysis of YE72 spirosin with Staphylococcus aureus V8 protease, they reacted markedly with peptide fragments of 27 and 35 kDa, suggesting the presence of an antigenic determinant on the fragments. When supernatant cell lysate from Escherichia coli K12 was chromatographed on DEAE-cellulose and Sepharose CL-6B columns successively, a 96-kDa protein with alcohol dehydrogenase (ADH) activity was always associated with reactivity to MAb-S50. These findings combined with N-terminal amino acid sequences clearly indicate the identity of spirosin to ADH in E. coli.

Alcohol Dehydrogenase↗
PubMed1995

[Intravenous MR arthrography of the knee].

A study was undertaken to determine whether or not intravenous MR arthrography can be used in clinical practice. Forty patients with internal derangement of the knee (11-68 years old) were imaged with MRI before and after intravenous injection of Gd-DTPA. In all knees there was enhancement of joint fluid, regardless of the amount of fluid. The peak enhancement of joint fluid was reached at 30 minutes after the administration of the contrast agent. The contrast between joint fluid and meniscus/cartilage was higher in MR arthrography than in proton density images. There was an increase in contrast between grade III lesions in the meniscus and intact meniscus on MR arthrography. It was concluded that intravenous MR arthrography can be a useful alternative to intra-articular arthrography.

Adolescent↗
PubMed1994

Dynamic magnetic resonance imaging for the evaluation of synovitis in patients with rheumatoid arthritis.

OBJECTIVE: To investigate whether the findings of magnetic resonance imaging (MRI) reflect rheumatoid synovitis. METHODS: Dynamic imaging enhanced with gadolinium-diethylenetriamine pentaacetic acid was performed on 10 affected knees of 9 patients with rheumatoid arthritis. Changes in signal intensity were correlated with pathologic findings in synovial biopsy specimens obtained during total knee arthroplasty. RESULTS: Enhancement was greater in regions with a higher degree of fibrin exudation, cellular infiltration, villous hypertrophy, vascular proliferation, and granulation formation. CONCLUSION: Dynamic MRI can be used for assessing local disease activity in rheumatoid synovium.

Aged↗
PubMed1994

Monoclonal antibodies to spirosin of Yersinia enterocolitica and analysis of the localization of spirosome by use of them.

Two hybridomas producing monoclonal antibodies (MAbs) were prepared by fusing myeloma cells (Sp2/0-Ag14) with mouse spleen cells immunized with purified spirosin from Yersinia enterocolitica SYT-11-72 (YE72). The antibodies produced by them were designated MAbs-S5 and S27. They were IgG2a and IgG1, respectively, both with kappa light chains. MAbs-S5 and S27 reacted specifically with spirosin from YE72. On Western blotting after limited proteolysis with Staphylococcus aureus V8 protease, YE72 spirosin revealed peptide fragments of 35 and 37 kDa reacting markedly with MAb-S5, which suggested the presence of an antigenic determinant on these fragments. By cellular fractionation of YE72 and subsequent EIA and Western blot analysis, spirosome was shown to be present in the cytoplasm of YE72.

Amino Acid Sequence↗
PubMed1993

[MR imaging of bone bruise associated with ACL tear].

The authors reviewed 56 MR studies of the knee performed for suspected cruciate ligament tear at the Tokyo Metropolitan Hiroo Hospital from April 1990 to March 1991. There were 10 patients with abnormal signal in the subcortical bone marrow. Eight of these patients had concomitant anterior cruciate ligament (ACL) tear with no evidence of fracture on plain radiographs of the knee. The abnormal signals were all seen in the lateral compartment, almost invariably in the middle third of the lateral femoral condyle and posterolateral aspect of the tibial plateau, and were of low intensity on T1-weighted and proton density images and of high intensity on T2-weighted images. It was speculated that these abnormalities resulted from impaction of the lateral femoral condyle into the posterior lip of the tibial plateau due to rotary subluxation of the tibia. One patient had a follow-up study three months later, which revealed complete resolution of bone bruise. It was concluded that bone bruise associated with ACL tear is seen specific locations, which may be a useful secondary sign of acute ACL tear.

Adolescent↗
PubMed1993

Age-related changes in collagen gel contraction by cultured human lung fibroblasts resulting in cross-over of contraction curves between young and aged cells.

We examined the effects of population doubling levels on collagen gel contraction by human lung fibroblasts (TIG-1). The sizes of gels at day 4 of culture, when the number of cells was the same as the initial number, were smaller with young cells than with aged cells. Therefore, retractive force had decreased with in vitro cellular aging. On the other hand, the lag time until gel contraction began became shorter with aging, resulting in the cross-over of contraction curves of young and aged cells. Morphological changes, such as pseudopodia protrusion, were suppressed in collagen gel. The surrounding collagen fibrils prevented young cells from moving more than aged cells. The weakened omnidirectional interaction with collagen fibrils on the entire surface of aged cells might result in an earlier occurrence of morphological change and, thereby, gel contraction.

Cell Division↗