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Articles by M Yamaguchi
Total Records ( 7 ) for M Yamaguchi
  M Yamaguchi , M Hayashi , S Fujita , T Yoshida , T Utsunomiya , H Yamamoto and K. Kasai

It has previously been reported that low-energy laser irradiation stimulated the velocity of tooth movement via the receptor activator of nuclear factor kappa B (RANK)/RANK ligand and the macrophage colony-stimulating factor/its receptor (c-Fms) systems. Matrix metalloproteinase (MMP)-9, cathepsin K, and alpha(v) beta(3) [(v)β3] integrin are essential for osteoclastogenesis; therefore, the present study was designed to examine the effects of low-energy laser irradiation on the expression of MMP-9, cathepsin K, and (v)β3 integrin during experimental tooth movement.

Fifty male, 6-week-old Wistar strain rats were used in the experiment. A total force of 10g was applied to the rat molars to induce tooth movement. A Ga-Al-As diode laser was used to irradiate the area around the moving tooth and, after 7 days, the amount of tooth movement was measured. To determine the amount of tooth movement, plaster models of the maxillae were made using a silicone impression material before (day 0) and after tooth movement (days 1, 2, 3, 4, and 7). The models were scanned using a contact-type three-dimensional (3-D) measurement apparatus. Immunohistochemical staining for MMP-9, cathepsin K, and integrin subunits of (v)β3 was performed. Intergroup comparisons of the average values were conducted with a Mann–Whitney U-test for tooth movement and the number of tartrate-resistant acid phosphatase (TRAP), MMP-9, cathepsin K, and integrin subunits of (v)β3-positive cells.

In the laser-irradiated group, the amount of tooth movement was significantly greater than that in the non-irradiated group at the end of the experiment (P < 0.05). Cells positively stained with TRAP, MMP-9, cathepsin K, and integrin subunits of (v)β3 were found to be significantly increased in the irradiated group on days 2–7 compared with those in the non-irradiated group (P < 0.05).

These findings suggest that low-energy laser irradiation facilitates the velocity of tooth movement and MMP-9, cathepsin K, and integrin subunits of (v)β3 expression in rats.

  R Yamaguchi , M Tanaka , K Kondo , T Yokoyama , Y Kaneko , M Yamaguchi , Y Ogata , O Nakashima , M Kage and H. Yano

Invasive micropapillary carcinoma of the breast is a distinct variant of breast cancer. In the present study, we analyzed potential immunophenotypic changes in invasive micropapillary carcinoma.


Specimens from 15 patients with invasive micropapillary carcinoma were analyzed using clinicopathological and immunohistochemical methods. We also examined the relationship between clinicopathological factors using the Ki-67 labeling index.


Immunohistochemical staining for cytoplasmic p63 expression was seen in four (27%) tumors, and p63 nuclear expression was also observed in four (27%) tumors. Involucrin and 34betaE12 were expressed in the invasive micropapillary carcinoma component of nine (60%) and four (27%) tumors, respectively. Cytokeratin 5/6 was expressed in three (20%) tumors and cytokeratin 14 staining was negative in all tumors. In one tumor (case 3), vimentin, epithelial membrane antigen and cytokeratin 8/18 were co-expressed. Four tumors (27%) were negative for the estrogen receptor/progesterone receptor/HER2. However, 11 out of 15 (73%) tumors were positive for the estrogen receptor. The Ki-67 labeling index was significantly higher in cases with p63 tumor expression than in those without (P < 0.0001), and also higher in cases with lymph node metastasis than in cases without (P = 0.0029).


Nuclear expression of p63, involucrin and 34betaE12 were detected indicating squamous differentiation. Cytoplasmic p63 expression was also identified. The fact that the Ki-67 labeling index was significantly higher in such cases may have been associated with the aggressive behavior of these tumors. Our findings suggest that the characteristic morphology of invasive micropapillary carcinomas may be due to immunophenotypical and oncogenic changes.

  M Yamaguchi , H Okada and Y. Namiki

A smart and efficient method for freeze substitution and serial sectioning of yeast cells is described. Yeast cells were placed in a single layer between two copper disks, rapidly frozen, freeze substituted and embedded in an epoxy resin. The cell layer was re-embedded by the same resin, the surface trimmed leaving 1 µm above the cell layer, and serially sectioned. The sections were collected on the two-slit grids and placed on a Formvar film mounted to cover the holes of an aluminum supporting rack. The grids were removed from the rack, stained together using a silicon tube and observed in a transmission electron microscope. The images of yeast cells observed were clear and natural, and would be useful for a detailed 3D structural analysis such as structome.

  M Yamaguchi and M. Kopecka

Phenotypes of the two temperature-sensitive actin mutants of Saccharomyces cerevisiae act1-1 and act1-2 at permissive, restrictive and semi-restrictive temperatures were studied by freeze fracture and thin section electron microscopy, and fluorescent microscopy. In contrast to secretory mutants where accumulations of either secretory vesicles, Golgi apparatus, or endoplasmic reticulum were reported, act1-1 and act1-2 mutants revealed accumulation of all the three components, even at permissive temperature. However, more distinct accumulation of secretory organelles was evident during cultivation at the sub-restrictive temperature of 30°C. At the restrictive temperature of 37°C, many cells died, and their empty cell walls remained. Some of the few living cells showed features of apoptosis. From the present study, actin cables are concluded to be necessary for (i) correct spatial positioning and orientation of secretary pathway to the bud and septum, and (ii) vectorial movement of vesicles of the secretory pathway along the actin cables to the bud and septum.

  M Yamaguchi , S. K Biswas , Y Kuwabara , M Ohkusu , M Shimizu and K. Takeo

The spindle pole body (SPB) in the interphase cell of the pathogenic yeast Cryptococcus neoformans was studied in detail by freeze-substitution and serial ultrathin sectioning electron microscopy. The SPB was located on the outer nuclear envelope and appeared either dumbbell- or bar shaped. The dumbbell-shaped SPBs were 228–365 nm long with amorphous spheres on each end, each sphere being 78–157 nm in diameter. The bar-shaped SPBs were 103–260 nm long and 32–113 nm thick. They consisted of filamentous materials. The dumbbell-shaped SPBs were more frequent (61%) than the bar-shaped SPBs. The bar-shaped SPBs may be regarded as dumbbell-shaped SPBs whose spherical parts became sufficiently small. There seemed to be no relationship between the SPB shape and the cell cycle stage of G1–G2, since both types of SPB appeared not only in unbudded cells but also in budded cells and their appearance seems to be random. It is not clear at present whether morphological changes between dumbbell- and bar shapes have any physiological function. The SPB tended to be localized away from the nucleolus (141° ± 44°), but localized randomly to the bud (97° ± 50°). The present study highlights the necessity of observing a large number of micrographs in three dimensions to describe accurately the ultrastructure of the SPB in yeast.

  S Tsutsui , M Yamaguchi , A Hirasawa , O Nakamura and T. Watanabe

A lactose-specific lectin with a molecular mass of about 25 kDa was purified from the skin mucus of a cartilaginous fish—the common skate (Raja kenojei). The complementary DNA sequence of the lectin was 1540 bp long and contained a reading frame encoding 226 amino acids, which showed ~38% identity to pentraxins of mammals and teleosts. Gene expression was observed in the skin, gill, stomach and intestine in the healthy skate. We also identified an isotype gene from the liver whose deduced amino-acid sequence shared 69.0% identity with the skin type gene. The antiserum detected protein in the skin, where the lectin is localized in the epidermal cells, and in the blood plasma. The lectin genes are multicopied in the common skate genome. Although pentraxins are acute phase proteins, mRNAs of both the isotypes were not upregulated after the in vivo challenge with formalin-killed Escherichia coli, which suggests that they are constantly present in the skin mucus and blood plasma to protect against pathogenic invasion. This lectin is the fifth type of lectin found in the cutaneous secretions of fish, demonstrating that skin mucus lectins have evolved with marked molecular diversity in fish.

  M Yamaguchi , S Takemori , M Kimura , Y Tanishima , T Nakayoshi , S Kimura , T Ohno , N Yagi , J. F. Y Hoh and Y. Umazume

To characterize the structure of jaw muscle fibres expressing masticatory (superfast) myosin, X-ray diffraction patterns of glycerinated fibres of dog masseter were compared with those of dog tibialis anterior in the relaxed state. Meridional reflections of masseter fibres were laterally broad, indicating that myosin filaments are staggered along the filament axis. Compared with tibialis anterior fibres, the peak of the first myosin layer line of masseter fibres was lower in intensity and shifted towards the meridian, while lattice spacings were larger at a similar sarcomere length. These suggest that the myosin heads of masticatory fibres are mobile, and tend to protrude from the filament shaft towards actin filaments. Lowering temperature or treating with N-phenylmaleimide shifted the peak of the first myosin layer line of tibialis anterior fibres towards the meridian and the resulting profile resembled that of masseter fibres. This suggests that the protruding mobile heads in the non-treated masticatory fibres are in the ATP-bound state. The increased population of weakly binding cross-bridges may contribute towards the high specific force of masticatory fibres during contraction. Electron micrographs confirmed the staggered alignment of thick filaments along the filament axis within sarcomeres of masticatory fibres, a feature that may confer efficient force development over a wide range of the sarcomere lengths.

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