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Biomedical subjects

W Naka

Publications and source records attributed to W Naka.

29 records · Page 2Linked to original sources
PubMed1993

Solitary cutaneous malignant schwannoma. Immunohistochemical and ultrastructural studies.

We describe two cases of malignant schwannoma in the skin that did not originate from a nerve trunk and was not associated with neurofibromatosis. Light microscopy showed that both tumors were composed predominantly of atypical spindle-shaped cells. Immunohistochemical analysis was performed with various monoclonal antibodies against mesenchymal determinants. In both patients, tumor cells were positive for S-100 alpha and S-100 beta, neuron-specific enolase, vimentin, neurofilament protein, and myelin basic protein, and negative for HMB-45, glial fibrillary acidic protein, epithelial membrane antigen, and desmin. Electron microscopy revealed that the tumor cells possessed indented nuclei with an electron-lucent cytoplasm. Immunoelectron microscopy showed diffuse fine granular staining for S-100 alpha, not detectable in normal Schwann cells, in the cytoplasm of the tumor cells.

Female↗
PubMed1989

Deoxyribonucleic acid hybridization studies of Exophiala dermatitidis and Exophiala jeanselmei.

Exophiala dermatitidis and Exophiala jeanselmei share similar morphological features and have been confused with each other. To clarify the relationship between the two fungi, we conducted a deoxyribonucleic acid (DNA)-DNA hybridization study using a dot blot method. Between E. dermatitidis and E. jeanselmei, only a very low level of DNA relatedness was seen and it was confirmed that these two fungi are distinct species based on DNA similarity. Close correspondence of DNA from the isolates of E. dermatitidis was obtained, whereas the isolates of E. jeanselmei were divided into 6 groups according to their DNA similarity and a possibility was shown that E. jeanselmei is composed of genetically heterogeneous groups. The subdivision of the species E. jeanselmei by the DNA-DNA hybridization method was in agreement with serotyping exoantigens. This result suggests that DNA-DNA hybridization studies provide an excellent tool for the identification and grouping of pathogenic dematiaceous fungi.

DNA, Fungal↗
PubMed1989

Angiosarcoma with dermal melanocytosis.

We report a case of angiosarcoma and dermal melanocytosis occurring simultaneously in the same lesion. We examined the primary and 2 metastatic lesions. Histopathologically, the anaplastic angiosarcoma cells had a tendency to form irregularly shaped small cavities. Immunohistochemically, they were strongly reactive with Ulex europaeus agglutinin (UEAI) stain. The mid and deep dermis of the same lesion had spindle or elongated slender melanocytes containing melanin granules. The melanocytes were positive with S-100 protein stain. Ultrastructurally, pinocytotic vesicles, fine filaments, and Weibel-Palade body-like dense granules were observed in the cytoplasm of angiosarcoma cells. Dermal melanocytes had external lamina and melanosomes in various stages. The melanocytes showed no similarity to the neoplastic tumor cells and there was no apparent intermediate form between the 2 kinds of cells. The etiological implications of dermal melanocytosis with a tumor of vascular origin are discussed.

Cell Division↗
PubMedDate not supplied

Differential expression of the 45 kDa protein (actin) during the dimorphic transition of Sporothrix schenckii.

We investigated the gene expression of a protein during the dimorphic transition from yeast to mycelial form of Sporothrix schenckii. Yeast cells were converted to mycelial cells in Sabouraud glucose broth at 25 degrees C. After 1, 3 and 5 days of culture, the intermediate form of cells between yeast and mycelium was obtained, and after 7 days these cells were morphologically similar to the mycelial cells. Proteins having the molecular weight of 45 kDa were found to by synthesized preferentially by intermediate form of day 7 and mycelial cells. On the other hand, the 45 kDa proteins were predominantly translated by the RNA isolated from the intermediate of day 7 and mycelial cells using in vitro cell-free translation assay. The 45 kDa proteins synthesized by mycelial cells were found to be identical with the 45 kDa translation products directed by the mRNA isolated from the intermediate and mycelial cells by V8 protease peptide mapping. The 45 kDa protein was considered to be actin by Western blot analysis using an anti-actin monoclonal antibody. These results suggest that the intermediate form of day 7 has the same phenotypes in the morphology and biosynthesis of actin as those of mycelial cells. The expression of the actin gene may be involved in the dimorphic transition of S. schenckii.

Actins↗
PubMedDate not supplied

Neutral red assay in minimum fungicidal concentrations of antifungal agents.

We assayed the fungicidal effects of antifungal agents using neutral red staining. Fungal elements of Trichophyton mentagrophytes and T. rubrum were treated with various concentrations of antifungal agents in 96-well filtration plates and then stained with neutral red. The amount of neutral red incorporated by the surviving viable cells was determined from the automated spectrophotometric readings at 550 nm. The minimum fungicidal concentrations (MFCs) of antifungal agents determined by this assay correlated well with those determined by conventional assay. This newly developed procedure should provide a rapid, reproducible, quantitative, qualitative and semi-automated susceptibility test for determination of the MFCs of the fungicidal agents.

Antifungal Agents↗
PubMedDate not supplied

Fonsecaea pedrosoi isolated from skin crusts of Bowen's disease.

Fonsecaea pedrosoi was isolated from scaly crusts of plaque lesions on the left thigh of a 60-year-old Japanese man. Histological examination confirmed these lesions to be due to Bowen's disease, and sclerotic cells were recognized in the stratum corneum. To our knowledge, this is the first study to demonstrate superficial colonization of a pre-existing skin lesion by F. pedrosoi.

Bowen's Disease↗
PubMedDate not supplied

Ultrastructure of Trichophyton mentagrophytes stained with neutral red.

The ultrastructure of Trichophyton mentagrophytes cells stained with neutral red was investigated using electron microscopy and X-ray microanalysis. Fixatives containing molybdenum and chromium were used to prevent the outflow of neutral red. Electron-dense particles composed of metals and dye were observed exclusively in the vacuoles, which were increased in number and size, but not near the cell wall. Results indicate that neutral red passes directly through the fungal cell wall and is incorporated into the vacuoles.

Electron Probe Microanalysis↗