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Biomedical subjects

T Saku

Publications and source records attributed to T Saku.

At least 19 recordsLinked to original sources
PubMed2004

[Epstein-Barr virus infection in lymphoepithelial carcinoma of salivary glands in Sichuan Chinese].

OBJECTIVE: To determine the prevalence of Epstein-Barr virus (EBV) infection in lymphoepithelial carcinoma (LEC) of salivary glands in Sichuan Chinese and discuss the role of EBV infection in pathogenesis of LEC. METHODS: Paraffin sections of 16 cases of LEC and 4 cases of benign lymphoepithelial lesion (BLEL) of salivary glands, 4 cases of non-specific chronic sialadenitis were examined by in situ hybridization for EBV encoded small RNA-1 (EBER-1) using 30-base synthesized oligonucleotide probe. RESULTS: Strong signals for EBER-1 were obtained in most of tumor cell nuclei in all the specimens of LEC (16/16); in contrast, there were no significant signals observed in the examination of 4 cases of BLEL and 4 cases of non-specific chronic sialadenitis. CONCLUSION: The results indicate that EBV plays an important role in the pathogenesis of LEC of salivary glands in Sichuan Chinese.

Adult↗
PubMed2004

[Epstein-Barr virus infection in benign lymphoepithelial lesions with malignant transformation of salivary glands].

OBJECTIVE: To examine the role of Epstein-Barr virus (EBV) infection in benign lymphoepithelial lesions with malignant transformation of salivary glands. METHODS: 2 cases benign lymphoepithelial lesions with focal malignant transformation (BLEL-FMT), 14 cases of malignant lymphoepithelial lesion (MLEL) and 4 cases of benign lymphoepithelial lesion (BLEL) of salivary glands, 4 cases of nonspecific chronic sialadenitis were examined. Sections were cut from the paraffin blocks and performed in situ hybridization (ISH) for EBV encoded small RNA-1 (EBER-1) using 30-base synthesized oligonucleotide probe and polymerase chain reaction (PCR) for BamHI-W regein of EBV DNA (123 bp). RESULTS: In ISH, strong signals for EBER-1 were obtained in most of epithelial cell nuclei in examined specimens of BLEL-FMT, no matter in benign or malignant areas and in all specimens of MLEL (14/14), PCR demonstrated a DNA fragment of 123 kbp in 2 cases of BLEL-FMT and 12 cases of MLEL (12/14). In contrast, there were no significant ISH/PCR signals in examined BLEL and nonspecific chronic sialadenitis. CONCLUSIONS: A few cases of MLEL may arise from BLEL and EBV may plays an important role in the pathogenesis of BLEL-FMT of salivary glands.

Epstein-Barr Virus Infections↗
PubMed2002

Phase diagram of interacting composite fermions in the bilayer nu=2/3 quantum hall effect.

We study the phase diagram of composite fermions (CFs) in the presence of spin and pseudospin degrees of freedom in the bilayer nu=2/3 quantum Hall (QH) state. Activation studies elucidate the existence of three different QH states with two different types of hysteresis in the magnetotransport. While a noninteracting CF model provides a qualitative account of the phase diagram, the observed renormalization of tunneling gap and a non-QH state at high densities are not explained in the noninteracting CF model, and are suggested to be manifestations of interactions between CFs.

Journal Article↗
PubMed2002

Electrically controlled nuclear spin polarization and relaxation by quantum-Hall states.

We study interactions between electrons and nuclear spins by using the resistance ( Rxx) peak which develops near the Landau-level filling factor nu = 2/3 as a probe. Temporarily tuning nu to a different value, nu(temp), with a gate demonstrates that the Rxx peak regenerates even after complete depletion ( nu(temp) = 0), while it rapidly relaxes on either side of nu(temp) = 1. This indicates that the nu = 2/3 domain morphology is memorized by the nuclear spins which can be rapidly depolarized by Skyrmions. An additional enhancement in the nuclear spin relaxation around nu = 1/2 and 3/2 suggests a Fermi sea of partially polarized composite fermions.

Journal Article↗
PubMed2002

Malignant melanoma of mandibular gingiva; the usefulness of fat-saturated MRI.

Case report of a histologically validated malignant melanoma affecting the mandibular molar gingiva in a 31-year-old woman. Tumour was evaluated by magnetic resonance (MR) imaging at 1.5-T, spin-echo 3 mm slice thickness with T1-weighted and fat-saturated T1-weighted images. The fat-saturated T1-weighted images demonstrated the lesion more clearly than conventional T1-weighted images.

Adult↗
PubMed2001

Charge excitations in easy-axis and easy-plane quantum Hall ferromagnets.

We study charge excitations in quantum Hall ferromagnets realized in a symmetric quantum well. Landau levels (LLs) with different subband and orbital indices crossing at the Fermi level act as up and down pseudospin levels. The activation energy measured as a function of the pseudospin Zeeman energy, Delta(Z), reveals easy-plane and easy-axis ferromagnetism for LL filling of nu = 3 and 4, respectively, for which the crossing levels have parallel and antiparallel spin. For nu = 4, we observe a sharp reduction in the gap for Delta(Z)-->0, which we discuss in terms of a topological excitation in domain walls akin to Skyrmions.

Journal Article↗
PubMed2001

Vascular invasion in squamous cell carcinomas of human oral mucosa.

The process of vascular invasion of human oral squamous cell carcinomas was histologically and immunohistochemically studied in surgical and autopsy specimens. Hematoxylin-eosin, Masson's trichrome, and immunohistochemical stainings for Ulex europaeus I lectin binding, CD31, and type IV collagen were done to differentiate lymphatic and blood vessels and to demonstrate basement membranes in vascular walls and around carcinoma cell nests was observed. With growth of tumor, there was mechanical disruption of vascular walls and endothelial cells by carcinoma cell nests. After disrupting vascular walls, they invaded into the lumen as clusters, not as single cells. At the blood vessel invasion sites, inflammatory reactions were seen around carcinoma cell nests inside as well as outside lumina with microthrombotic reactions due to endothelial injury. At the lymphatic invasion sites, carcinoma cell nests maintained their volume inside the lumen and the cells adhered tightly to each other, and inflammatory reaction was scarcely seen. These findings showed that mechanical pressure has an important role in the vascular invasion of human oral squamous cell carcinoma.

Animals↗
PubMed2001

Enhanced expression of basement-membrane-type heparan sulfate proteoglycan in tumor fibro-myxoid stroma of intrahepatic cholangiocarcinoma.

To investigate the molecular mechanism for enhanced fibrous stroma formation in intrahepatic cholangiocarcinoma (ICC), we surveyed the expression pattern of basement-membrane-type heparan sulfate proteoglycan (HSPG; also known as perlecan) at the core protein and the mRNA level in ICC as well as in other liver neoplasms and reactive hepatic diseases. Immunohistochemistry of paraffin-embedded liver sections with hyaluronidase pretreatment showed that HSPG was present in small amounts in normal liver around the bile ducts and the blood vessels within the portal area. There was no evident expression within the hepatic lobules. Intense immunoexpression of HSPG was seen in the tumor-specific fibro-myxoid stroma of ICC and metastatic liver cancer originating from the colon. However, tumor-specific stroma of hepatocellular carcinomas showed little or no expression of HSPG. At the mRNA level, signals for HSPG were found in tumor cells of cholangiocarcinoma and metastatic colonic carcinomas, and in myofibroblasts in the tumor fibro-myxoid-specific stroma. From immunoprecipitation and reverse transcription-polymerase chain reaction (RT-PCR) analyses, a cultured human intrahepatic cholangiocarcinoma cell line (CCKS1), was found to express high levels of HSPG core protein and mRNA. These findings suggest that biliary and metastatic colon carcinoma cells as well as stromal myofibroblasts have a potential for HSPG production. In order to investigate the growth, invasion and metastatic ability of ICC, further study of the 'self-made' stromal component of ICC may provide a new approach.

Adult↗
PubMed2000

Perlecan (heparan sulfate proteoglycan) gene expression reflected in the characteristic histological architecture of salivary adenoid cystic carcinoma.

In order to determine the role of the basement membrane-type heparan sulfate proteoglycan (HSPG), known as perlecan, in the formation of the characteristic cribriform 'structures of salivary adenoid cystic carcinomas, the mode of expression of mRNA for the core protein of HSPG was investigated by using in situ hybridization (ISH) both in surgical specimens and in a cell system (ACC3) of adenoid cystic carcinomas. In the surgical specimens, the mRNA for the HSPG core was more intensely expressed in solid tumor cell nests, especially in smaller ones. Within the nests, the signals were detected almost exclusively in cuboidal cells forming small pseudocysts. In contrast, signals were absent in flat cells forming large pseudocysts or in carcinoma cell nests attaching to the peripheral nerves or blood vessels. In normal salivary gland tissues, myoepithelial cells expressed the mRNA at a high level, but acinar and duct epithelial cells did not. In the time-course experiment of ACC3 cells, signals for HSPG core increased with time and reached the maximum on day 4, decreasing thereafter in a culture condition in which cells reached confluence in a week. The results indicate that HSPG is biosynthesized by adenoid cystic carcinoma cells which are in the proliferation phase, and that tumor cells producing HSPG tend to form initial structures of stromal pseudocysts.

Carcinoma, Adenoid Cystic↗
PubMed2000

Enamel proteins and extracellular matrix molecules are co-localized in the pseudocystic stromal space of adenomatoid odontogenic tumor.

In order to examine the functional differentiation of tumor cells of adenomatoid odontogenic tumor (AOT) as ameloblasts and to determine the participation of the extracellular matrix (ECM) in the formation of its characteristic histologic architecture, tissue samples from five cases of adenomatoid odontogenic tumor were examined by immunohistochemical staining for enamel proteins and ECM molecules. Amelogenin, enamelin, laminin, heparan sulfate proteoglycan, fibronectin, collagen type IV and type V were immunolocalized within the luminal space and along the inner rim of duct-like structures. Eosinophilic hyaline droplets within the whorled or rosette masses of tumor cells showed basically the same staining pattern as the luminal contents. High columnar tumor cells that formed duct-like structures were immunopositive for amelogenin, while the staining intensity decreased with flattening of the cells, which was a result of luminal growth. The findings suggest that the constituent cells of duct-like structures are differentiated once to ameloblasts but fail to mature further due instead to increased production of ECM molecules and due to their retention in the lumina. It is possible to regard these special structures in AOT as stromal pseudocysts.

Amelogenin↗
PubMed2000

Melanotic neuroectodermal tumor of infancy in the mandible: report of a case.

A case of melanotic neuroectodermal tumor of infancy occurring in the mandible is described. The patient was a 1-month-old boy with a rapidly growing tumor of the mandible. Computed tomography showed 2 well-defined osteolytic lesions in the right mandible. Histopathologic diagnosis of a biopsy specimen was melanotic neuroectodermal tumor of infancy. The tumor was excised with removal of the surrounding bone, but 1(1/2) months later it recurred, and segmental mandibulectomy and reconstruction of the defect with a titanium miniplate was performed. Retrospectively, evidence of recurrence was noted on computed tomography taken on the tenth postoperative day. The recurrence was caused by incomplete removal of the tumor. Histopathologically, the tumor cells of the recurrent lesion were dispersed extensively in the bone marrow, and bone remodeling was active. The surgical procedure may have stimulated tumor cell proliferation and reactive bone formation. The patient was followed for 2 years with no evidence of recurrence or metastasis.

Humans↗
PubMed1999

Intracortical hemangioma of the mandible. Case report.

We describe the first reported case of an intracortical hemangioma of the mandible in a 13-year-old Japanese girl. Panoramic radiography and CT demonstrated a small osteolytic lesion which had expanded and thinned the cortex at the inferior border of the left mandible. The lesion enhanced on post-contrast T1-weighted MRI. The diagnosis was confirmed by histopathology following block excision. Intracortical hemangioma should be considered in the differential diagnosis of radiolucent lesions orf the mandible

Adolescent↗
PubMed1999

Basement membrane heparan sulfate proteoglycan (perlecan) synthesized by ACC3, adenoid cystic carcinoma cells of human salivary gland origin.

The biosynthesis of basement membrane heparan sulfate proteoglycan (HSPG), known as perlecan, in ACC3 cells established from a adenoid cystic carcinoma of the human salivary gland was studied using metabolic labeling and immunoprecipitation with discriminative antibodies specific for HSPG core protein. Treatment of immunoprecipitated HSPG with HNO2, heparitinase, and chondroitinase ABC revealed that ACC3 cells synthesized HSPG molecules composed of 470-kDa core protein and heparan sulfate but not of chondroitin sulfate. The core protein was shown to contain complex type N-linked oligosaccharides by digestion with N-glycanase and endoglycosidase H. Pulse-chase experiments showed that the mature form of HSPG was formed in the cells in 30 min and released into the medium thereafter. Degradation of HSPG was also found in the chase period of 3 h. In time course experiments, HSPG was found to be synthesized maximally at day 4 after plating, deposited in the cell layer maximally at day 6, and secreted maximally at day 8. This was also confirmed by immunofluorescence, Northern blotting, and in-situ hybridization. The results indicate that ACC3 cells synthesize, secrete and degrade basement membrane type HSPG, which is analogous to those produced by other cell types, and that the biosynthesis and secretion of HSPG in ACC3 cells are strictly regulated by the cell growth, that may be reflected in the characteristic histology of adenoid cystic carcinomas.

Basement Membrane↗
PubMed1999

High-molecular-weight fibronectin synthesized by adenoid cystic carcinoma cells of salivary gland origin.

To understand the morphogenesis of characteristic cribriform structures and the frequent invasion of salivary adenoid cystic carcinomas (ACC) along such basement membrane-rich structures as peripheral nerves, we have isolated fibronectin (FN) from the culture media of ACC3 cells established from a parotid ACC and characterized its glycosylation and alternative splicing status. FN isolated from ACC3 cells (ACC-FN) showed a molecular mass of 315 kDa in SDS-PAGE and was less heterogeneous and larger than plasma FN (pFN) or FNs from other cell sources. Differential enzymatic treatments of immunoprecipitated ACC-FN with neuraminidase, peptide-N-glycosidase F and endo-alpha-N-acetylgalactosaminidase revealed that ACC-FN was composed of a polypeptide chain of 270 kDa, with 10 kDa each of N-linked and O-linked oligosaccharide chains. Reverse transcription polymerase chain reaction (RT-PCR), in-situ hybridization, and immunofluorescence studies showed that most ACC-FNs contained ED-A, ED-B and IIICS regions in the molecules. This alternative splicing status of ACC-FN seemed to contribute to its less heterogeneous and larger molecular form. Cell attachment assay demonstrated that ACC-FN was more potent than pFN in adhesion of ACC3 cells. The results indicated that ACC-FN may function as a substrate for attachment of ACC3 cells, or that ACC3 cells trap and retain ACC-FN in their pericellular space. This isoform of FN may play an important role in the mode of invasion of ACC and the formation of stromal pseudocysts in the characteristic cribriform structure of ACC.

Alternative Splicing↗
PubMed1998

Intracellular transport of basement membrane-type heparan sulphate proteoglycan in adenoid cystic carcinoma cells of salivary gland origin: an immunoelectron microscopic study.

ACC3, a human adenoid cystic carcinoma cell system of salivary gland origin, is able to synthesize and secrete a large amount of basement membrane molecules in vitro. To define the ultrastructural secreting pathway of these molecules, we immunolocalized heparan sulphate proteoglycan (HSPG) in ACC3 for 7 days of culture. In the early stage of culture, the main compartments immunolabelled were rough endoplasmic reticulum (rER) and small secretory vesicles. From days 3 to 4 after plating, it was noticed that HSPG was localized in partially dilated spaces of the perinuclear, rER and Golgi cisternae and in lysosomes or those fused with multivesicular bodies and endosomes. On and after day 5, almost every Golgi apparatus showed marked dilatation of the cisternae and HSPG was immunolocalized in these dilated spaces. In the later stage of culture, autophagic vacuoles or secondary lysosomes, which were simultaneously labelled for HSPG and cathepsin D, were accumulated in the cytoplasm. HSPG deposition in the intercellular space was clearly demonstrated from day 1 and increased during the culture. The results indicate that ACC3 cells have an enhanced turnover cycle for HSPG: not only its biosynthesis but also degradation of both endogenous or exogenous HSPG. Such intracellular events may be reflected in the characteristic histology and biological behaviour of adenoid cystic carcinomas.

Biological Transport↗
PubMed1998

Adenosquamous carcinoma of the tongue: report of a case with histochemical, immunohistochemical, and ultrastructural study and review of the literature.

A rare case of oral adenosquamous carcinoma in a 78-year-old woman is reported. The tumor occurred in her tongue and metastasized to the submandibular and cervical lymph nodes. Histologically, the tumor showed invasive growth involving the submucosal and muscle layers. Its solid carcinomatous nests exhibited ductal differentiation in the deeper aspects and squamous differentiation toward the surface. Histochemical examination revealed an accumulation of acid mucopolysaccharide in the ductal lumina, and the ductal cells were immunohistochemically positive for carcinoembryonic antigen, epithelial membrane antigen, cancer antigen 15-3 and Ulex europaeus agglutinin I. Ultrastructurally, tonofibrils, desmosomes and numerous cytoplasmic processes were common features of the tumor cells. In addition, true glandular structures and pseudocysts were seen in areas. Clinical features of 13 adenosquamous carcinomas in the literature were analyzed.

Aged↗
PubMed1998

Effects of the anticancer drug cocktail "UFT" on metastatic potentials of squamous cell carcinoma (O-1N) in a hamster model.

UFT, a mixture of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) and uracil, is one of the most widely used anticancer agents. The tissue localization and the efficacy of UFT in preventing lymph node metastasis were studied in hamsters transplanted with oral squamous cell carcinoma (termed "O-1N") which has high lymph node metastatic potency. After UFT administration for 14 consecutive days, the incidence of lymph node metastasis was significantly decreased (16% vs 58%). When UFT was administered orally for 3 consecutive days to hamsters bearing O-1N, and tissue concentrations of tegafur and 5-FU were measured by gas chromatography, the value of 5-FU was significantly higher in the primary transplant tumour, cervical lymph nodes with or without metastasis, and liver, than in the normal oral tissues. When 14C-UFT(14C-tegafur + uracil, a uracil/FT molar ratio of 4) was administered orally for 3 consecutive days to hamsters bearing O-1N, the 14C-tegafur level of tissue homogenates in the buccal and metastatic tumours was within the range of normal oral tissues, but the localization of silver grains was significantly higher in tumour cells than in the oral normal tissues. The results suggest that UFT would be useful for treatment and prevention of lymph node metastasis of oral carcinomas because of the high accumulation of active metabolites in metastatic and non-metastatic lymph nodes.

Administration, Oral↗