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Biomedical subjects

Y Asada

Publications and source records attributed to Y Asada.

At least 37 records · Page 2Linked to original sources
PubMed2001

Selective expression of aquaporin 1, 4 and 5 in the rat middle ear.

The middle ear cavity is an air-filled space that must be maintained for effective sound transmission to the inner ear. To examine the mechanisms of water homeostasis in the middle ear, we investigated whether aquaporins (AQPs), a family of water-permeable channels, were expressed in the middle ear. Reverse transcription-polymerase chain reaction and immunoblot analyses revealed that mRNAs encoding AQP1, 4 and 5 (but not 2 or 3) subtypes were expressed in rat middle ear epithelium; AQP1, 4 and 5 were detected as 28-, 30- and 30-kDa proteins, respectively. Immunohistochemical analysis showed that AQP1 was localized at capillary endothelial cells and fibroblasts in lamina propria mucosae; AQP4 was present solely at the basolateral membrane of ciliated cells, whereas AQP5 was on the apical surface of ciliated cells as well as of flat and columnar epithelial cells. The characteristic different localizations of AQP1, 4 and 5 subtypes in the middle ear suggest that middle ear water homeostasis requires the coordinated operation of these AQPs.

Animals↗
PubMed2001

Morphological architecture and distribution of blood capillaries and elastic fibres in the human skin.

This study was undertaken to clarify the morphological features in the blood capillary and elastic fibre distribution of the human skin in terms of susceptibility to pressure sore development. Skin tissues were obtained from bony areas: the sacrum and ischial tuberosity and non-bony area: the centre of the gluteus maximus of 5 aged subjects post mortem for examination using light and scanning electron microscopy. It was observed that the sacral skin had finger-like papillae and underneath the blood capillary loops were most numerous. In the ischial skin the dermal papillae consisted of a combination of finger-like and trapezoid shapes having moderate density of blood capillaries. In contrast, the dermal papillae in the gluteal skin were almost flat, so that the blood capillaries were scattered. The size of elastic bundles in the papillary layer of the sacral, ischial and gluteal skin ranged from 2 to 3 microns, 5 to 10 microns, and 3 to 5 microns, respectively. The elastic fibres were densely distributed in the ischial skin while less so in the sacral skin.

Aged↗
PubMed2001

Primary cutaneous Langerhans cell histiocytosis showing malignant phenotype in an elderly woman: report of a fatal case.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a proliferating disorder of Langerhans cells (LC) that are characterized by the presence of Birbeck granules. LCH has been considered to be a disease of childhood and there have been limited cases of adult LCH. We report here a fatal case of histiocytic tumor showing Langerhans cell phenotype, arising in the skin of a 74-year-old woman. METHOD: In addition to routine histological and immunohistological sections, electron microscopic examination and human androgen receptor gene (HUMARA) assays were performed. RESULTS: Histological examination revealed a dense dermal infiltrative proliferation of fairly large tumor cells with abundant ill-defined cytoplasms and oval or indented nuclei, in which numerous eosinophils were associated with the tumor nests. Tumor cells were positive with anti-S-100 and CD1a antibodies but negative with HMB-45 antibody or other epithelial or lymphocytic markers. Ultrastructural analysis showed typical Birbeck granules in the cytoplasm of the tumor cells. HUMARA assay of the tumor tissue revealed the nonrandom X inactivation pattern, indicating the clonal proliferation. CONCLUSIONS: We diagnosed this tumor as Langerhans cell histiocytosis with a clonal neoplastic phenotype originated in the skin. Although she demonstrated no recurrence nor metastases for 6 months after surgical resection of primary skin lesion and subsequent radiation therapy, the tumor recurred and extended multisystemically, and she died of multiple organ failure 14 months after initial diagnosis. Therefore, we would like to emphasize this case as LC "sarcoma" or "malignant" LCH.

Aged↗
PubMed2001

Clinical management of intraductal papillary mucinous tumors of the pancreas based on imaging findings.

The aim of this study was to assess the imaging findings of pathologically proven intraductal papillary-mucinous tumors of the pancreas and the natural history of follow-up cases, and to optimize the therapeutic management of patients with these tumors according to their imaging findings. All nine patients with main duct type tumors were histologically diagnosed as having adenocarcinoma or adenoma, with no hyperplastic lesion. The images failed to discriminate between the two histologic types. In 26 patients with branch duct type tumors, all but one with intraductal mural nodules or tumors of > or = 30 mm had adenocarcinoma or adenoma, regardless of the caliber of the main duct. Of the nine patients with tumors < 30 mm and no mural nodules. three had adenoma, and six had hyperplasia. All of four patients had hyperplasia, with the additional caliber of the main duct being < 6 mm. In a series of 23 cases in which the patient was followed-up, no apparent progression was found in 17 patients who had no mural nodules and tumors of < 30 mm. Given these results, patients with main duct type tumors, and those with branch duct type tumors showing mural nodules or a tumor diameter of > or = 30 mm, are at high risk of developing neoplasms, including adenocarcinoma, for which surgical resection should be considered, whereas those patients with tumors < 30 mm and no mural nodules can be followed.

Adenocarcinoma↗
PubMed2001

Adrenomedullin and proadrenomudullin N-terminal 20 peptide (PAMP) are present in human colonic epithelia and exert an antimicrobial effect.

The hypotensive and vasorelaxing peptides adrenomedullin (AM) and its gene-related peptide, proadrenomedullin N-terminal 20 peptide (PAMP), were found to be distributed on the surface of the colonic mucosa. AM and PAMP showed dose-dependent antimicrobial activity against E. coli. The results suggest that the novel vasoactive peptides AM and PAMP play an important role in mucosal defence.

Adrenomedullin↗
PubMed2001

5 alpha-reductase type 2 is constitutively expressed in the dermal papilla and connective tissue sheath of the hair follicle in vivo but not during culture in vitro.

Recent studies suggest that 5 alpha-reductase type 2 (5 alpha R2) rather than 5 alpha R1 plays a key role in the pathogenesis of male-pattern baldness. To clarify the localization of the androgen receptor (AR), 5 alpha R1, and 5 alpha R2 in the hair follicle, we investigated the expression of the corresponding genes by RT-PCR using microdissected hair follicles. AR and 5 alpha R1 mRNAs were expressed in all portions of the hair follicle. By contrast, 5 alpha R2 mRNA was expressed only in mesenchymal portions that included the dermal papilla and connective tissue sheath, and hardly any was expressed in epithelial portions. The intensity of expression of these genes in each portion of the hair follicles did not differ between follicles from balding and nonbalding scalp. We also examined the expression of these genes in cultured fibroblasts derived from the dermal papilla and connective tissue sheath. Although expression of AR and 5 alpha R1 mRNAs was easily detected, there was no obvious expression of 5 alpha R2 mRNA in either type of cell. Type-specific inhibition of 5 alpha R activity by MK386 and MK906 confirmed these patterns of expression of 5 alpha R mRNA. Thus, the expression of 5 alpha R2 mRNA seems to be characteristic of freshly microdissected mesenchymal portions of the hair follicle, but such expression might not be maintained in culture.

Adult↗
PubMed2001

Identification of amino acid residues essential for the substrate specificity of Flavobacterium sp. endo-beta-N-acetylglucosaminidase.

The gene encoding the endo-beta-N-acetylglucosaminidase from Flavobacterium sp. (Endo-Fsp) was sequenced. The Endo-Fsp gene was overexpressed in Escherichia coli cells, and was purified from inclusion bodies after denaturation by 8 M urea. The renatured Endo-Fsp had the same optimum pH and substrate specificity as the native enzyme. Endo-Fsp had 60% sequence identity with the endo-beta-N-acetylglucosaminidase from Streptomyces plicatus (Endo-H), and the putative catalytic residues were conserved. Site-directed mutagenesis was done at conserved residues based on the three-dimensional structure and mutagenesis of Endo-H. The mutant of Glu-128, corresponding to Glu-132 in Endo-H and identified as an active site residue, was inactivated. Mutagenesis around the predicted active site of Endo-Fsp reduced the enzymatic activity. Moreover, the hydrolytic activity toward hybrid-type oligosaccharides was decreased compared to that toward high-mannose type oligosaccharides by mutagenesis of Asp-126 and Asp-127. Therefore, site-directed mutagenesis of some of these conserved residues indicates that the predicted active sites are essential to the enzymatic activity of Endo-Fsp, and may have similar roles in catalysis as their counterparts in Endo-H.

Amino Acid Sequence↗
PubMed2001

Biosynthesis and secretion of adrenomedullin and proadrenomedullin N-terminal 20 peptide in a rat model of endotoxin shock.

To study the biosyntheses and pathophysiological roles of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) in septic shock, we compared the time course of plasma concentrations of these peptides and blood pressure in rats injected with either 0.9% saline (control group) or lipopolysaccharide (LPS group). The plasma AM concentration in the LPS group did not increase 30 and 60 min after LPS injection, at which time points the blood pressure remained low. Thereafter, AM rapidly increased, and it amounted to 35 times the basal value 4 h after injection, when the blood pressure returned to the basal level. The increment of plasma PAMP in the LPS group was lower than that of AM. We also examined the tissue concentration of AM and PAMP--as well as the tissue expression of proadrenomedullin (proAM) mRNA--in the LPS and control groups. LPS significantly increased the tissue concentrations of AM and PAMP in the lung, but decreased them in the adrenal gland and cardiac atrium. The LPS injection augmented proAM gene transcription in the lung, adrenal gland and aorta. In an immunohistochemical examination, AM staining was intense in alveolar endothelial cells of the lung in the LPS group. Thus, this septic shock model had high plasma levels of PAMP as well as AM, while the biosynthesis and secretion of the two peptides may have been differentially regulated in various tissues of rats injected with LPS. The present results suggest that these two bioactive peptides may play different roles in the pathophysiology of septic shock.

Adrenomedullin↗
PubMed2000

Roles of His-79 and Tyr-180 of D-xylose/dihydrodiol dehydrogenase in catalytic function.

Mammalian dimeric dihydrodiol dehydrogenase is identical with d-xylose dehydrogenase and belongs to a protein family with prokaryotic proteins including glucose-fructose oxidoreductase. Of the conserved residues in this family, either His-79 or Tyr-180 of d-xylose/dihydrodiol dehydrogenase has been proposed to be involved in the catalytic function. Site-directed mutagenesis was used to examine the roles of the two residues of the monkey enzyme. A mutant, Y180F, was almost inactive, but, similarly to the wild-type enzyme, exhibited high affinity for NADP(H) and fluorescence energy transfer upon binding of NADPH. The H79Q mutation had kinetically largest effects on K(d) (>7-fold increase) and K(m) (>25-fold increase) for NADP(H), and eliminated the fluorescence energy transfer. Interestingly, the dehydrogenase activity of this mutant was potently inhibited with a 190-fold increase in the K(m) for NADP(+) by high ionic strength, which activated the activity of the wild-type enzyme. These results suggest a critical role of Tyr-180 in the catalytic function of this class of enzymes, in addition to functions of His-79 in the coenzyme binding and chemical steps of the reaction.

Animals↗
PubMed2000

Construction of a physical and transcript map flanking the imprinted MEST/PEG1 region at 7q32.

MEST/PEG1, a gene expressed paternally in mesodermal derivatives in early embryonic stages, is the first imprinted gene mapped to chromosome 7q32. Since imprinted genes are clustered in general at a chromosomal region, we speculated that a similar imprinted-gene cluster may exist at chromosome region 7q32 and that the functions of some such genes may contribute to the phenotype of Silver-Russell syndrome including maternal uniparental disomy for chromosome 7 (maternal UPD7). As an initial step toward the isolation of imprinted genes at 7q32, we adopted an integrated approach involving the construction of a PAC contig and ESTs mapping in the vicinity of MEST. Here, we have constructed a complete contig of PAC and BAC clones and a transcript map spanning the entire approximately 1-Mb region between D7S530 and D7S649. We developed 60 novel STSs and precisely mapped 47 genes/ESTs. This map contains a putative autistic disorder locus that has been suggested to be localized near markers D7S530 and D7S684. This integrated physical and transcript map provides a valuable resource for identification of an imprinted gene(s) in this region as well as a candidate gene(s) for autistic disorder.

Base Sequence↗
PubMed2000

Heterologous expression of clostridial hydrogenase in the Cyanobacterium synechococcus PCC7942.

The Clostridium pasteurianum hydrogenase I has been expressed in the cyanobacterium Synechococcus PCC7942. The Shine-Dalgarno sequence of the structural gene encoding hydrogenase I from C. pasteurianum was changed to that of the cat (chloramphenicol acetyltransferase) gene. The hydrogenase gene was cloned downstream of a strong promoter, isolated from Synechococcus PCC7942, with the cat gene as a reporter gene. Expression of clostridial hydrogenase was confirmed by Western and Northern blot analyses in Synechococcus and Escherichia coli, whereas in vivo/in vitro measurements and activity staining of soluble proteins separated on non-denaturing polyacrylamide gels revealed functional expression of hydrogenase only in cyanobacterial cells. The changed Shine-Dalgarno sequence appeared to be essential for the functional expression of clostridial hydrogenase in Synechococcus, but had no influence on the expression and activity of clostridial hydrogenase expressed in E. coli.

Blotting, Northern↗
PubMed2000

Synthesis of neoglycoenzymes with homogeneous N-linked oligosaccharides using immobilized endo-beta-N-acetylglucosaminidase A.

A procedure for the enzymatic synthesis of neoglycoenzymes is described. The gene encoding endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) was overexpressed in Escherichia coli as a fusion protein linked to glutathione S-transferase (GST). GST-Endo-A fusion was extracted as a soluble protein. The fusion protein was purified to homogeneity with glutathione-Sepharose 4B and showed transglycosylation activity toward high-mannose-type glycopeptides without removing the GST moiety. The GST-Endo-A immobilized on glutathione-Sepharose 4B retained its transglycosylation activity. The immobilized enzyme could transfer (Man)(6)GlcNAc en bloc to partially deglycosylated ribonuclease B without damaging its enzyme activity. The immobilized GST-Endo-A should be very useful for synthesizing active neoglycoenzymes attached with homogeneous N-linked oligosaccharides.

Animals↗
PubMed2000

Reduction of blood loss using tranexamic acid in total knee and hip arthroplasties.

There have been several attempts to reduce postoperative blood loss in patients undergoing total arthroplasty. Benoni et al. reported the usefulness of tranexamic acid in total knee arthroplasty (TKA). We investigated its effect in TKA and total hip arthroplasty (THA). Blood loss was significantly reduced in patients given tranexamic acid in both the TKA and THA groups, and no severe complications, such as venous or pulmonary thrombosis, were noted in any of the patients who received the agent. Administration of tranexamic acid seems to be useful for reducing postoperative blood loss in TKA and THA.

Antifibrinolytic Agents↗
PubMed2000

Flavonoid constituents from Glycyrrhiza glabra hairy root cultures.

An unusual biflavonoid named licoagrodin was isolated from the hairy root cultures of Glycyrrhiza glabra (Leguminosae) along with three prenylated retrochalcones, licoagrochalcones B, C, D, a prenylated aurone, licoagroaurone and four known prenylated flavonoids, licochalcone C, kanzonol Y, glyinflanin B and glycyrdione A. From the glycosidic fraction, a isoflavone glycoside, licoagroside A, and a maltol glycoside, licoagroside B were isolated together with four known isoflavone glycosides, two flavone C-glycosides, and three other glycosides. Their structures were elucidated on the basis of spectroscopic evidence.

Chalcones↗
PubMed2000

Plate assay for endo-beta-N-acetylglucosaminidase activity using a chromogenic substrate synthesized by transglycosylation with Arthrobacter endo-beta-N-acetylglucosaminidase.

The transglycosylation activity of Arthrobacter endo-beta-N-acetylglucosaminidase (Endo-A) was used for the enzymatic synthesis of a novel oligosaccharide, Man6GlcNAc-5-bromo-4-chloro-3-indolyl-beta-glucoside (Man6GlcNAc-Glc-beta-X). Various endo-beta-N-acetylglucosaminidases hydrolyzed this oligosaccharide, producing Man6GlcNAc and Glc-beta-X. The E. coli strains coexpressing Endo-A and beta-glucosidase formed blue colonies in the presence of Man6GlcNAc-Glc-beta-X. Therefore, endo-beta-N-acetylglucosaminidase activity could be directly detected by the plate assay. This simple plate assay is useful for screening microorganisms for endo-beta-N-acetylglucosaminidase activity.

Journal Article↗