Ei Kawahara

Na+-coupled transport of l-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney

The mechanism of Na(+)-dependent transport of L-carnitine via the carnitine/organic cation transporter OCTN2 and the subcellular localization of OCTN2 in kidney were studied. Using plasma membrane vesicles prepared from HEK293 cells that were stably transfected with human OCTN2, transport of L-carnitine via human OCTN2 was characterized. Uptake of L-[(3)H]carnitine by the OCTN2-expressing membrane vesicles was significantly increased in the presence of an inwardly directed Na(+) gradient, with an overshoot, while such transient uphill transport was not observed in membrane vesicles from cells that were mock transfected with expression vector pcDNA3 alone. The uptake of L-[(3)H]carnitine was specifically dependent on Na(+) and the osmolarity effect showed that Na(+) significantly influenced the transport rather than the binding. Changes of inorganic anions in the extravesicular medium and of membrane potential by valinomycin altered the initial uptake activity of L-carnitine by OCTN2. In addition, the fluxes of L-carnitine and Na(+) were coupled with 1:1 stoichiometry. Accordingly, it was clarified that Na(+) is coupled with flux of L-carnitine and the flux is an electrogenic process. Furthermore, OCTN2 was localized on the apical membrane of renal tubular epithelial cells. These results clarified that OCTN2 is important for the concentrative reabsorption of L-carnitine after glomerular filtration in the kidney.

Expression of glial fibrillary acidic protein gfap in peripheral nerve sheath tumors a comparative study of immunoreactivity of gfap vimentin s 100 protein and neurofilament in 38 schwannomas and 18 neurofibromas

Immunoreactivity of glial fibrillary acidic protein (GFAP) in 38 schwannomas and 18 neurofibromas was evaluated and compared with the reactivity of vimentin, S-100 protein, and neurofilament protein. All cases were positive for vimentin and S-100 protein. GFAP was positively stained in the neoplastic cells of 15 of 38 schwannomas (38%) and in two of 18 neurofibromas (11%). The extensively stained GFAP-positive tumors tended to be deeply situated in the body. The GFAP-positive cells were usually spindle-shaped and appeared preferentially in the perivascular region of hyalinized, thick blood vessels.

Association of vascular endothelial growth factor expression with angiogenesis and lymph node metastasis in nasopharyngeal carcinoma.

Objective: Recent experimental evidence indicates that angiogenesis affects tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is considered to be an important regulator of tumor angiogenesis. The present study was designed to examine the role of VEGF on angiogenesis and lymph node metastasis in primary nasopharyngeal carcinomas (NPCs). Study Design: Formalin‐fixed paraffin‐embedded biopsy specimens were obtained from 29 primary NPCs that consisted of 22 differentiated nonkeratinizing carcinomas and seven undifferentiated carcinomas. Methods: Microvessels were highlighted by staining endothelial cells with von Willebrand factor (VWF) using immunohistochemical techniques, and were counted (per × 400 field) in the most active area of angiogenesis on light microscopy. The expression of VEGF was also studied with immunohistochemistry. Positive ratio for VEGF was graded on a scale of 1 and 2. Scale 1 represents patients with less than the mean value of the positive ratio, and scale 2 represents patients with more than the corresponding value. Results: There was a significant correlation between increased microvessel count and the progression of regional lymph node involvement. The microvessel counts and the progression of N factor were significantly higher in scale 2 patients than in scale 1 patients. Conclusion: These results suggest that VEGF plays an important role in lymph node metastasis through induction of angiogenesis in NPCs.

Specific Deposition of Serum Amyloid A Protein 2 in the Mouse

The homogenates of amyloid‐laden spleens prepared from CBA mice were analysed by SDS‐PAGE and immunoblotting employing rat anti‐murine monoclonal antibody, MSA 4–26, The results showed that the precursor of amyloid A protein (AA). serum amyloid A protein 2 (SAA2). and SAA intermediates with molecular weights of 10,000, 9000, and 8000 were contained in amyloid‐laden tissues. The experiment using sonicated spleen cells and acute phase murine sera showed a delay in the degradation rate of SAA2 on cell fragments and the remains of SAAI in supernatants. This result can explain disappearance of SAA2 from the murine serum during amyloidogenesis in vivo.

Malignant Melanoma Arising in a Dermoid Cyst of the Ovary

Autopsy findings of primary malignant melanoma arising in an ovarian dermoid cyst in an 86‐year‐old woman are presented. The right ovary was replaced by a dermoid cyst, 14 × 9 × 9 cm in size, in which several nodular tumors with diameters less than 3.2 cm were localized. They comprised diffusely proliferating anaplastic cells with prominent nucleoli. Some of them contained melanin pigments in the cytoplasm. The tumor cells were positive for S‐100 protein and ultrastructurally showed melanosomes. In addition, several benign pigmented lesions resembling dermal nevus, pigmented schwannoma, or cellular blue nevus were present in the dermoid cyst, one of which contained a malignant melanomatous component. Histologic transition between benign and malignant components and the presence of another small focus of atypical melanocytes in the benign lesion suggested that the malignant melanoma arose in close association with the previously existing benign pigmented lesions in the dermoid cyst.

Immunohistochemical studies on the tissue localization of collagen types I, III, IV, V and VI in schwannomas: Correlation with ultrastructural features of the extracellular matrix

SummaryThe distinctive tissue localization of collagen types in typical schwannomas with Antoni type A and B areas was demonstrated immunohistochemically using affinity-purified antibodies against types I, III, IV, V and VI collagen and comparative ultrastructural studies were made on the extracellular matrix components. Antoni type A tissue, which was composed of tightly packed spindle cells with long cytoplasmic processes surrounded by a continuous basement membrane and a few fibrillar components of the extracellular matrix, was almost exclusively immunoreactive for type IV collagen, presumably representing the basement membrane. Verocay bodies, which are organoid structures of Antoni type A tissue, had a variety of more abundant extracellular fibrous components, such as banded collagen fibrils, fibrous longspacing fibrils and microfibrils. These were positive for type I and III, as well as type IV collagen. In Antoni type B areas, where two types to tumor cells designated Schwann cell-like and fibroblastlike were scattered in large amounts of amorphous extracellular matrix containing microfibrils and thick banded collagen fibrils, type VI collagen as well as types I, III and IV collagen were consistently detected. Type V collagen was localized in dense fibrous tissue areas and around blood vessels. These findings indicate that the differently organized cellular patterns of schwannomas, identified as Antoni types A and B, are characterized not only by the ultrastructural features of the extracellular matrix, but also by the distinctive collagen types produced by neoplastic Schwann cells.

Differential diagnosis of pleomorphic adenoma by immunohistochemical means

Immunohistochemical study of major salivary gland tumours was performed on 60 pleomorphic adenomas, five basal cell adenomas and 10 adenoid cystic carcinomas to determine the diagnostic value of each antigen. Immunoreactivity examined were intermediate filaments (keratin, vimentin, desmin and glial fibrillary acidic protein [GFAP]) and related substances (actin, S-100 protein and secretory component). In pleomorphic adenomas, there was positive immunoreactivity for GFAP which was not observed in normal tissue or other neoplastic tissues. Immunoreactivity of GFAP was closely related to myxomatous and early chondromatous differentiation in pleomorphic adenoma. It is considered that GFAP immunoreactivity should be assessed in the occasional differential diagnostic dilemma of pleomorphic adenoma versus adenoid cystic carcinoma and basal cell adenoma, because of its ability to show potential and definite myxochondromatous differentiation.

Overexpression of E2F1 associated with LOH at RB locus and hyperphosphorylation of RB in non-small cell lung carcinoma

Purpose E2F1 plays a critical role in cell proliferation, and its function is controlled by the retinoblastoma (RB) protein. We examined the expression of E2F1 and the aberration of RB gene and protein to elucidate what factors contribute to the overexpression of E2F1 in non-small cell lung carcinomas.Methods The expression level of E2F1 in tissues of non-small cell lung carcinomas was measured by means of quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. For RB, we examined loss of heterozygosity (LOH) by PCR-restriction fragment length polymorphism and a variable number of tandem repeats, and protein expression by immunohistochemistry.Results Fifteen cases of carcinoma (46%) showed high transcription levels of E2F1 gene. Immunohistochemically, almost all (14 of 15) cases overexpressing E2F1 mRNA were positive for E2F1 protein. LOH at the RB locus was found in 13 of 30 informative cases. In 13 cases with LOH, ten showed overexpression of E2F1 mRNA and protein. Immunohistochemical positivity for phosphorylated RB protein was also closely correlated with overexpression of E2F1.Conclusions Our results suggest that overexpression of E2F1, induced both by LOH at the RB locus and anomalous phosphorylation of the RB protein, is involved in the development of non-small cell lung carcinoma.

Spindle epithelial tumor with thymus-like differentiation (SETTLE) of the thyroid

Tumors of the so‐called intrathyroidal epithelial thymoma type are a rare group of thyroid neoplasm tumors. Of this type of tumor, spindle epithelial tumor with thymuslike differentiation (SETTLE) has been reported only 17 times in English literature.

Carcinosarcoma of the esophagus. An immunohistochemical and electron microscopic study.

Immunohistochemical and electron microscopic examinations were made of a carcinosarcoma of the esophagus in an 80‐year‐old man. An immunohistochemical examination showed that sarcomatous spindle cells were vimentinpositive, whereas squamous carcinoma cells were keratin‐positive. No coexistence of vimentin and keratin in a single tumor cell was found. Electron microscopically, the sarcomatous spindle cells were characterized by well‐developed rough endoplasmic reticulum, abundant intermediate filaments, and the occasional presence of peripheral aggregates of microfilaments. No definite desmosomes were identified among these cells. These results appear to indicate that most of the spindle‐shaped tumor cells assume fibroblastic cellular features and synthesize the intermediate filament protein usually expressed in mesenchymal cells, even though such tumor cells could be epithelial in origin.