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T Maeda

Publications and source records attributed to T Maeda.

At least 19 recordsLinked to original sources
PubMed1995

Cloning and characterization of seven cDNAs for hyperosmolarity-responsive (HOR) genes of Saccharomyces cerevisiae.

Yeast cells can respond and adapt to osmotic stress. In our attempt to clarify the molecular mechanisms of cellular responses to osmotic stress, we cloned seven cDNAs for hyperosmolarity-responsive (HOR) genes from Saccharomyces cerevisiae by a differential screening method. Structural analysis of the clones revealed that those designated HOR1, HOR3, HOR4, HOR5 and HOR6 encoded glycerol-3-phosphate dehydrogenase (Gpd1p), glucokinase (Glk1p), hexose transporter (Hxt1p), heat-shock protein 12 (Hsp12p) and Na+, K+, Li(+)-ATPase (Ena1p), respectively. HOR2 and HOR7 corresponded to novel genes. Gpd1p is a key enzyme in the synthesis of glycerol, which is a major osmoprotectant in S. cerevisiae. Cloning of HOR1/GPD1 as a HOR gene indicates that the accumulation of glycerol in yeast cells under hyperosmotic stress is, at least in part, caused by an increase in the level of GPDH protein. We performed a series of Northern blot analyses using HOR cDNAs as probes and RNAs prepared from cells grown under various conditions and from various mutant cells. The results suggested that all the HOR genes are regulated by common signal transduction pathways. However, the fact that they exhibited certain distinct responses indicated that they might also be regulated by specific pathways in addition to the common pathways. Ca2+ seemed to be involved in the signaling systems. In addition, Hog1p, one of the MAP kinases in yeast, appeared to be involved in the regulation of expression of HOR genes, although its function seemed to be insufficient for the overall regulation of expression of these genes.

Adenosine Triphosphatases↗
PubMed1995

Expression and localization of glucose transporter 1 (GLUT1) in the rat oviduct: a possible supplier of glucose to embryo during early embryonic development.

The oviduct fluid mainly derived from the oviduct epithelium is reported to provide the environment necessary for embryonic development. To elucidate the origin of glucose in the oviduct fluid, we examined the expression and localization of glucose transporter 1 (GLUT1) in the rat oviduct by Northern blot analysis, immunoblot analysis and immunohistochemistry using both light and electron microscopy. Northern blot and immunoblot analyses both showed the presence of the GLUT1 mRNA and protein. Specific staining for GLUT1 was observed in the ampulla and the isthmus, but only slightly in the fimbria and the utero-tubal junction. Staining was confined to the luminal surface of the epithelial mucosa. Immunoelectron microscopic analysis revealed that GLUT1 was observed only on the surface of the microvilli in non ciliated secretory cells, but not in ciliated cells. These findings suggest that GLUT1 plays an important role in the glucose transfer from the oviduct epithelium into the lumen and in maintaining the adequate glucose concentration of the oviduct fluid for embryonic development in rat oviduct.

Animals↗
PubMed1995

Three-dimensional structure in solution of the calcium channel blocker omega-conotoxin MVIIA.

The three-dimensional solution structure of omega-conotoxin MVIIA, a 25-mer peptide antagonist of N-type calcium channels, was determined by two-dimensional 1H NMR spectroscopy with simulated annealing calculations. A total of 13 converged structures of omega-conotoxin MVIIA were obtained on the basis of 273 experimental constraints, including 232 distance constraints obtained from nuclear Overhauser effect (NOE) connectivities, 22 torsion angle (phi, chi 1) constraints, and 19 constraints associated with hydrogen bonds and disulfide bonds. The atomic root mean square difference about the averaged coordinate positions is 0.47 +/- 0.08 A for the backbone atoms (N, C alpha, C) and 1.27 +/- 0.14 A for all heavy atoms of the entire peptide. The molecular structure of omega-conotoxin MVIIA is composed of a short triple-stranded antiparallel beta-sheet. The overall beta-sheet topology is +2x, -1, which is the same as that reported for omega-conotoxin GVIA, another N-type calcium channel blocker. The orientation of beta-stranded structure is similar to each other, suggesting that the conserved disulfide bond combination is essential for the molecular folding. We have recently determined by using alanine substitution analyses that Tyr 13 is essential for the activity of both toxins. On the basis of functional and structural analysis, it is shown that both omega-conotoxin MVIIA and GVIA retain a similar conformation to locate Tyr 13 in the appropriate position to allow binding to N-type calcium channels. These results provide a molecular basis for understanding the mechanism of calcium channel modulation through the toxin-channel interaction and insight into the discrimination of different subtypes of calcium channels.

Amino Acid Sequence↗
PubMed1995

Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of an SH3-containing osmosensor.

The role of mitogen-activated protein (MAP) kinase cascades in integrating distinct upstream signals was studied in yeast. Mutants that were not able to activate PBS2 MAP kinase kinase (MAPKK; Pbs2p) at high osmolarity were characterized. Pbs2p was activated by two independent signals that emanated from distinct cell-surface osmosensors. Pbs2p was activated by MAP kinase kinase kinases (MAPKKKs) Ssk2p and Ssk22p that are under the control of the SLN1-SSK1 two-component osmosensor. Alternatively, Pbs2p was activated by a mechanism that involves the binding of its amino terminal proline-rich motif to the Src homology 3 (SH3) domain of a putative transmembrane osmosensor Sho1p.

Amino Acid Sequence↗
PubMed1995

Peptide ligands for integrin alpha v beta 3 selected from random phage display libraries.

The integrin alpha v beta 3 binds promiscuously to cell-adhesive proteins: vitronectin, fibronectin, and several others containing the RGD motif. We have explored molecular recognition by alpha v beta 3 through selection of ligands from large random libraries of peptides displayed on phage. Ligands bound by alpha beta 3 consisted primarily of RGD peptides; however, these peptides showed considerable heterogeneity with respect to the identities of amino acids flanking RGD. The tolerance of alpha v beta 3 for RGD peptides of diverse composition is consistent with its role in vivo as a versatile receptor for RGD-containing extracellular matrix proteins. Peptide ligands for alpha v beta 3 also included a novel binding sequence, identical to a tetrapeptide found in vitronectin, which is a candidate for a synergistic site in this adhesive protein that may act in concert with RGD to promote molecular recognition.

Amino Acid Sequence↗
PubMed1995

Small hepatocellular carcinoma of single nodular type: a specific reference to its surrounding cancerous area undetected radiologically and macroscopically.

A total of 128 surgically resected small hepatocellular carcinomas, measuring less than or equal to 3 cm in diameter, were studied by both macroscopic and histologic examinations. In 95 single nodular-type tumors of the 128 lesions, eight tumors were associated with the cancerous areas of well differentiated hepatocellular carcinoma around the nodule. These surrounding cancerous areas went undetected by both the preoperative radiological examinations and the gross findings of resected specimens. Based on the immunohistochemical findings, the labeling index, both of the proliferating cell nuclear antigen (PCNA) and of the Ki-67 in the surrounding cancerous areas, were lower than that of the main nodules but higher than in the nontumorous liver parenchyma in seven of eight cases. These results suggest that the main nodule was generated from the surrounding cancerous area, supporting the hypothesis of a stepwise progression of HCC. Even if the tumor seems to be a small and single nodular type, it is recommended that its surrounding areas should be closely examined and the surgical cutting margin should be made more than 1.0 cm away from the main nodule at hepatic resection.

Carcinoma, Hepatocellular↗
PubMed1995

A 69-kDa membrane protein associated with lipopolysaccharide (LPS)-induced signal transduction in the human monocytic cell line THP-1.

Lipopolysaccharide (LPS) triggers a wide range of cellular responses in mammalian cells. Several proteins, including CD14, have been reported to possess LPS binding capacity. However, the signal transduction molecule(s) and pathway(s) through which LPS induces cellular responses have not been identified. A rabbit antiserum (5299), which had been made against the N-terminal 20-amino-acid sequence of the cytokine, soluble immune response suppressor, unexpectedly activated the human monocyte cell line THP-1 as assessed by tumor necrosis factor (TNF alpha) production. Normal rabbit serum or IgG caused no TNF production, while antiserum 5299 induced TNF at a 1:10(4) dilution. The activity of antiserum 5299 was not due to endotoxin contamination, since antiserum 5299 contained less endotoxin than required for activation of THP-1 and the TNF-inducing activity disappeared when the antiserum was boiled. Moreover, the activity was recovered in purified immunoglobulin G fraction from the antiserum (5299 IgG). These results suggest that antiserum 5299 contains an antibody which recognizes a signal-transducing molecule. THP-1 desensitized by incubation with LPS for 24 hr could not respond to LPS or antiserum 5299 while responsiveness to phorbol ester remained, suggesting that the signals induced by the antiserum 5299 and LPS are transduced through at least a partially common pathway. Western blotting with antiserum 5299 showed a 69-kDa protein which rapidly appeared in Triton X-100-insoluble fraction after stimulation with LPS or 5299 IgG, suggesting an association of 69-kDa protein with the cytoskeleton. Furthermore, two mutant cell lines were isolated (T-15 and T-25) from gamma-irradiated THP-1 which lack responsiveness to LPS. In these mutant cell lines, the 69-kDa protein was not observed in Triton X-100-insoluble fraction after stimulation with LPS. It is proposed that this protein may play an important role in LPS-stimulated signal transduction.

Blotting, Western↗
PubMed1995

Up-regulation of integrin alpha 5 beta 1 expression by interleukin-6 in rabbit corneal epithelial cells.

Interleukin-6 (IL-6) has been shown to promote the attachment of rabbit corneal epithelial cells to fibronectin-coated substratum and ex vivo migration of the cells on the corneal stroma. To examine whether IL-6 promotes cell attachment through up-regulation of expression of integrin alpha 5 beta 1, i.e., the major cell surface fibronectin receptor, we quantified the levels of both alpha 5 and beta 1 subunit transcripts by reverse transcription-polymerase chain reaction in cultured rabbit corneal epithelial cells pretreated with various concentrations of IL-6. The levels of both alpha 5 and beta 1 mRNAs were dose-dependently elevated by IL-6, attaining 1.5- and 1.8-fold increases, respectively, at 10 ng/ml. The stimulatory effect of IL-6 was transient; the levels of both subunit mRNAs reached a maximum 1 h after the addition of IL-6 and returned to the basal levels after 6 h. The IL-6-induced up-regulation of integrin alpha 5 and beta 1 mRNAs was also confirmed by Northern blot analysis. These results indicate that the increased attachment of corneal epithelial cells to fibronectin and enhanced ex vivo migration on corneal stroma by IL-6 is, at least in part, due to the temporal up-regulation of integrin alpha 5 beta 1 expression in corneal epithelial cells.

Amino Acid Sequence↗
PubMed1995

Neurochemical heterogeneity of the primate nucleus accumbens.

In order to further investigate the neurochemical anatomy of the primate nucleus accumbens (NAC), the distributions of the neuropeptides leucine-enkephalin (Leu-ENK), neurotensin (NT), and substance P (SP) and of haloperidol-induced c-fos expression were investigated in the macaque monkey using immunohistochemical methods. To define the boundaries of the NAC, dopamine (DA) and tyrosine hydroxylase (TH) immunohistochemistry was performed. In addition, to formulate the distinction between subdivisions of the nucleus accumbens, immunohistochemistry for calbindin-D28 (CBD) and SP was employed. In general, the medial part of NAC, which consisted of small to medium-sized cells, was low for CBD immunoreactivity and moderate to high for SP immunoreactivities, while the dorsolateral part, which was composed of small cells, showed the opposite pattern of immunostaining for CBD and SP. Many Leu-ENK-immunoreactive perikarya were observed in the dorsal NAC at its middle and caudal levels. There were moderate densities of Leu-ENK-positive fibers throughout the medial part of the NAC. At the dorsolateral margin of the NAC, Leu-ENK-positive fibers formed patches. Most NT-positive perikarya were found in the dorsolateral subdivision. SP-positive perikarya were scarce in the NAC. Dense distribution of NT- and SP-containing fibers or puncta were observed in the mediodorsal part (medial subdivision), where a dense field of DA-immunoreactive fibers was observed. The ventral part (ventral subdivision) contained moderate numbers of NT- and SP-immunoreactive fibers. Haloperidol-induced c-fos expression was very extensive in the medial half of NAC, particularly in the mediodorsal region, which overlapped with the DA- and peptide-rich region. The present study indicates that the NAC of the primate can be subdivided into at least three subterritories, the dorsolateral, medial and ventral subdivision, by neuropeptide histochemistry as well as by the response of its constituent neurons to haloperidol.

Animals↗
PubMed1995

Auxiliary heterotopic partial liver transplantation in pigs with acute liver failure.

Fulminant hepatic failure is usually fatal without liver transplantation; however, orthotopic liver transportation is often difficult to perform due to the high risk of coagulopathy and the development of multiple organ failure. Auxiliary heterotopic partial liver transplantation (APLT), However, has the potential to provide an effective hepatic support system considering that the host liver is left in situ and the surgical procedure is less invasive. In this report, we describe the beneficial effects of performing 60% APLT on the hepatic function and survival of pigs with acute hepatic failure induced by hepatic artery ligation. The pigs were divided into a control group of nine animals (group 1) that had portal vein and hepatic artery ligation with a side-to-side portacaval shunt, and an APLT group of seven animals (group 2) that had portal vein and hepatic artery ligation with APLT. The two left lateral lobes of the donor liver were resected, reducing the liver weight to about 60%, and the graft was placed in the right subhepatic space. No deaths occurred intraoperatively. In group 1, eight pigs died of massive liver necrosis within 48 h and one died between 48 and 72 h (median survival 23 h). In group 2, two pigs died within 72 h due to preservation or anesthetic problems, but five survived for more than 3 days (median survival 13.4 days), with a significant difference between the two groups (P < 0.05). One animal was killed 30 days after APLT and excellent graft function was demonstrated by the synthesis of clotting factors, ammonia detoxification, and glucohomeostasis. Moreover, evidence of hepatic regeneration was found in the transplanted livers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Interleukin-6 stimulates cell proliferation of rat pituitary clonal cell lines in vitro.

We investigated the effect of recombinant human IL-6 (rhIL-6) on cell proliferation using the MtT/E rat pituitary tumor cell line, which was recently established by Inoue et al. This cell line expresses the homeodomain protein Pit-1/GHF 1 and does not produce any significant amount of pituitary hormones, but retains its tumorigenicity by back-transplantation into rats, resulting in production of prolactin. MtT/E cells were seeded into Falcon 24-well plates at a density of 2 x 10(4) cells/well in a cultured medium, containing 10% horse serum and 2.5% fetal bovine, with test drug. After four-days (12 days for the time-course study) incubations, the cells were counted using a hemocytometer. Incubation for 4 days with rhIL-6 caused concentration-dependent stimulation of MtT/E cell growth and [3H]-thymidine incorporation into MtT/E cells. Addition of 20 ng/ml rhIL-6 to the culture medium stimulated MtT/E cell growth in a time-dependent manner, withdrawal of rhIL-6 from the culture medium reduced MtT/E cell growth, and re-addition of rhIL-6 to the culture medium again stimulated MtT/E cell growth. Among the cytokines tested, granulocyte colony-stimulating factor (rh G-CSF) also showed a slight but significant mitogenic activity on the MtT/E cells. Analysis of 125I-rhIL-6 binding to the MtT/E cells indicated a dissociation constant of 0.953 x 10(-9) mmol/l and the presence of 968 binding sites per cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Combined hepatocellular and cholangiocarcinoma: proposed criteria according to cytokeratin expression and analysis of clinicopathologic features.

We herein evaluated 36 cases of combined hepatocellular and cholangiocarcinoma (cHCC-CC) (including 29 surgically resected and seven autopsy cases) by the immunohistochemical methods of anticytokeratin antibodies 7 and 19, and then analyzed the clinicopathologic features by comparing cHCC-CC with ordinary hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). The results indicated that even if mucin production could not be confirmed, nine cases with HCC areas that showed a histological resemblance to CC also showed immunohistological biliary differentiation. Therefore, we advocate that these HCC with biliary differentiation based on an immunohistochemical analysis should thus be included in the criteria of cHCC-CC in broad terms. Regardless of the extent of mucin production, the cHCC-CCs as indicated by an immunohistochemical analysis are considered to have a similar background to that of ordinary HCCs regarding such factors as the average age, male:female ratio, hepatitis B surface antigen (HBsAg) and hepatitis C virus antibody (HCVAb) positivity, alpha-fetoprotein level, and the presence of cirrhosis. However, cHCC-CCs tend to metastasize to many organs and the lymph nodes, and, as a result, have a poor prognosis.

Bile Duct Neoplasms↗
PubMed1995

Heterogeneity, polyploidy, aneusomy, and 9p deletion in human glioblastoma multiforme.

The short arm of chromosome 9 is frequently deleted in malignant gliomas. We used locus-specific probes for interferon-A (IFNA) and D9S3 in combination with a chromosome 9 centromeric probe to detect genetic aberrations on a cell-by-cell basis in touch preparations of 30 glioblastomas by fluorescence in situ hybridization. Seven (23%) of 30 tumors had deletions in > 70% of cells; the IFNA locus was deleted in all seven, but the D9S3 locus was deleted in only five of the seven. The latter data confirm that a tumor suppressor gene on 9p relevant to glioblastoma multiforme lies between D9S3 and IFNA. Eleven tumors had deletions in 20-40% of cells, more than three standard deviations above the level in control tissues. The remaining tumors had deletions in < 20% of cells. The seven tumors with the lowest percentage of deleted cells each had more than one genetically abnormal population of cells. In total, 10 cases were of this type (i.e., aneusomic for chromosome 9). Three of these 10 tumors had hybridization patterns consistent with polyploidy.

Adult↗
PubMed1995

T cell autoreactivity against a 28 kD biliary protein (B1-p28) in primary biliary cirrhosis.

BACKGROUND/AIMS: Cellular immune responses against biliary epithelial cells are important in understanding the pathogenesis of primary biliary cirrhosis. We previously reported a biliary antigen B1 which stimulated peripheral T lymphocytes of primary biliary cirrhosis as a possible, non-mitochondrial target of biliary epithelial cells. Further characterization of B1 was performed. METHODS: To confirm localization of B1 in biliary epithelial cells, a mouse monoclonal antibody was raised against B1. As B1 could be separated into two main components by SDS-PAGE under reducing condition, these components were individually cut out from Western blots and converted into antigen-bearing particles for a proliferation assay to detect the antigenic component responsible for stimulating lymphocytes. The relation of this proliferation to HLA DR antigens was also analyzed. RESULTS: Immunohistochemically, B1 was shown to be specifically expressed on biliary epithelial cells of human liver tissue. Of two components from B1 under reducing condition, prominent proliferation against B1-p28, a 28 kD component of B1 was detected in primary biliary cirrhosis. The reactivities were significantly higher than chronic liver diseases (p < 0.001) or normal controls (p < 0.001). Furthermore, high responders to B1-p28 were observed frequently in primary biliary cirrhosis patients with HLA DR8 (p < 0.02), which was susceptible to the development of primary biliary cirrhosis. CONCLUSIONS: These data suggest B1-p28 expressed on biliary epithelial cells is a candidate for the target antigen of primary biliary cirrhosis in addition to mitochondrial autoantigens. Further characterization of B1-p28 may provide new insight into the autoimmune mechanisms of primary biliary cirrhosis.

Aged↗
PubMed1995

Patch sensor detection of glutamate release evoked by a single electrical shock.

We tried to detect minimal stimulation-induced glutamate overflow from the surface of a hippocampal slice using an outside-out patch electrode excised from pyramidal cell membranes. The amplitude of the stimulation-induced patch current was dependent on the distance between the slice surface and the tip of patch sensor. The current-voltage relations of the stimulation-induced patch current were similar to those of the current evoked puff by application of L-glutamate to the patch. This indicates that the stimulation-induced patch current was produced by glutamate released from presynaptic terminals, and thus this technique may be useful in the study of transmitter release evoked by minimal electrical stimulation in brain slices.

Action Potentials↗
PubMed1995

Primary leiomyosarcoma of the maxilla with regional lymph node metastasis. Report of a case and review of the literature.

A rare case of oral leiomyosarcoma diagnosed with the aid of immunohistochemical and electron microscopic examinations together with a review of the literature are reported. The patient was a 70-year-old Japanese man. The primary tumor involved the maxillary gingiva and bone and metastasized to the cervical lymph nodes. On histologic examination the tumor showed invasive growth into the maxillary bone. It was composed of interlacing fascicles of spindle-shaped cells with eosinophilic cytoplasm and elongated, blunt-ended nuclei. The tumor formed extensive metastatic foci in the cervical lymph nodes. On immunohistochemical examination most of the tumor cells were positive for desmin, smooth muscle-specific actin, and myosin. The ultrastructural characteristics of the tumor cells were abundant microfilaments, pinocytotic vesicles, and basement membrane formation. The findings were indicative of a tumor demonstrating myogenic differentiation. A review of the literature during the past 50 years disclosed a total of 60 oral leiomyosarcomas, including our case.

Actin Cytoskeleton↗
PubMed1995

Evidence for a calcium regulated, bidirectional intronic promoter in the murine TCR V alpha 1 gene.

Previous studies of the TCR alpha chain gene have located promoter elements 5' to the start of the various V alpha genes. The only fully characterized enhancer for the entire alpha chain gene (V, J and C genes) has been located approximately 3 kb from the 3' end of C alpha. We now report the existence of additional regulatory elements located in the introns of several murine V alpha genes (V alpha 1, V alpha 3 and V alpha B6.2.16). In the case of V alpha 1, this element appears to be a promoter with bidirectional activity that is not T cell specific. Interestingly, upstream of the promoter in the antisense strand, an open reading frame has been found that codes for a small molecular weight protein (approximately 60 amino acids) that contains a proline-rich region and a tyrosine-isoleucine motif that has homology to Ig beta (the B29 gene product). A rabbit antiserum made against this sequence has confirmed its existence by Western blot and immunoprecipitation. Thus this V alpha 1 intronic promoter has the potential not only to induce the formation of a truncated V alpha 1 gene product, but also regulates the expression of a small molecular weight protein that may be involved in lymphocyte antigen receptor signaling. The activity of this promoter is regulated by changes in intracellular calcium. In the presence of ionomycin the promoter is down-regulated in the sense direction and its activity is enhanced in the antisense direction. This result suggests that this promoter can act differentially to produce two very different gene products. The bidirectional V alpha 1 promoter appears to be the first in the Ig superfamily to induce potentially functional proteins in both directions.

Amino Acid Sequence↗