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Y Ikeda

Publications and source records attributed to Y Ikeda.

At least 145 records · Page 8Linked to original sources
PubMed2001

CD34 expression on long-term repopulating hematopoietic stem cells changes during developmental stages.

The CD34 antigen serves as an important marker for primitive hematopoietic cells in therapeutic transplantation of hematopoietic stem cells (HSC) and gene therapy, but it has remained an open question as to whether or not most HSC express CD34. Using a competitive long-term reconstitution assay, the results of this study confirm developmental changes in CD34 expression on murine HSC. In fetuses and neonates, CD34 was expressed on Lin(-)c-Kit(+) long-term repopulating HSC of bone marrow (BM), liver, and spleen. However, CD34 expression on HSC decreased with aging, and in mice older than 10 weeks, HSC were most enriched in the Lin(-)c-Kit(+)CD34(-) marrow cell fraction. A second transplantation was performed from primary recipients who were transplanted with neonatal Lin(-)c-Kit(+) CD34(high) HSC marrow. Although donor-type HSC resided in CD34-expressing cell fraction in BM cells of the first recipients 4 weeks after the first transplantation, the stem cell activity had shifted to Lin(-)c-Kit(+)CD34(-) cells after 16 weeks, indicating that adult Lin(-)c-Kit(+)CD34(-) HSC are the progeny of neonatal CD34-expresssing HSC. Assays for colony-forming cells showed that hematopoietic progenitor cells, unlike HSC, continue to express CD34 throughout murine development. The present findings are important because the clinical application of HSC can be extended, in particular as related to CD34-enriched HSC and umbilical cord blood HSC.

Age Factors↗
PubMed2001

The critical role of the stem region as a functional domain responsible for the oligomerization and Golgi localization of N-acetylglucosaminyltransferase V. The involvement of a domain homophilic interaction.

We demonstrated that a region in the stem of N-acetylglucosaminyltransferase V (GnT-V), a Golgi resident protein, is not required for enzyme activity but serves as functional domain, responsible for intracellular localization. Deletion of the domain led to complete retention of the kinetic properties but resulted in the cell surface localization of the enzyme as well as its efficient secretion into the medium. The lack of this domain concomitantly abolished the disulfide-mediated oligomerization of GnT-V, which appears to confer the Golgi retention. When the domain was inserted into the stem region of a cell surface-localized type II membrane protein, the resulting chimeric protein was substantially oligomerized and predominantly localized in the intracellular organelle. Furthermore, it was found that the presence of this domain is exclusively responsible for homo-oligomer formation. This homophilic interaction appears to involve a hydrophobic cluster of residues in the alpha-helix of the domain, as indicated by secondary structure predictions. These findings suggest that the domain specifically participates in the Golgi retention of GnT-V, probably via inducing homo-oligomer formation, and would also provide a possible mechanism for the oligomerization, which is critical for localization in the Golgi.

Animals↗
PubMed2001

Enhanced low shear stress induced platelet aggregation by Shiga-like toxin 1 purified from Escherichia coli O157.

The effect of Shiga-like toxin 1 (Stx1) produced by Escherichia coli O157 on platelets was studied with an argon laser light-assisted shear-induced platelet aggregometer and with binding assays. Stx1 markedly enhanced the platelet aggregation under low shear stress but did not affect it under high shear stress. Minimal concentration of Stx1 required for the enhancement was 0.25 ng/ml, and almost maximal enhancement was observed at a final concentration of > or =2.5 ng/ml. This enhanced platelet aggregation disappeared after leukocyte depletion from normal platelet-rich plasma with a specific filter. In contrast, a standard platelet aggregometer was unable to detect this enhanced platelet aggregation in either the presence or the absence of ADP. 125I-labeled purified Stx1 did not specifically bind to normal washed platelets depleted of leukocytes, and thin-layer chromatographic analysis of glycolipids extracted from normal platelet lysates also confirmed that leukocyte-depleted normal platelets lack Stx1-specific receptor globotriaosylceramide (Gb3). Supernatant from the monocyte suspension stimulated with Stx1 exhibited the enhanced low shear stress induced platelet aggregation, but that from the polymorphonuclear cell suspension did not. Several cytokines produced from monocytes reproduced this event in vitro. Further, plasmas from six out of seven patients with hemolytic uremic syndrome (HUS) had activity similar to the purified Stx1. This activity was almost totally impaired after treatment of HUS plasmas with Gb3 in accord with reduction of plasma Stx1 levels. Taken together, these results indicate that platelets lack Gb3, and Stx1 appears to modulate platelet aggregation in an indirect fashion, presumably by the release of cytokines or chemical compounds from the target tissues.

Bacterial Toxins↗
PubMed2001

Induction of antigen-specific human CD4(+) T cell anergy by peripheral blood DC2 precursors.

Dendritic cells (DC) are antigen (Ag)-presenting cells that are essential for initiation of T cell-dependent immunity, and distinct DC subsets are known to direct different classes of immune responses. DC2 precursors (pDC2) or plasmacytoid DC were recently identified as a Th2-skewing and IFN-alpha-producing human DC subset. Here, we demonstrate that pDC2 enriched from human peripheral blood have a capacity to induce an anergic state in human Ag-specific CD4(+) T cell lines. Tetanus toxoid-specific T cell lines incubated with tetanus toxoid-pulsed autologous pDC2 failed to proliferate in secondary cultures with optimal Ag stimulation. T cell anergy induction required TCR engagement with Ag/MHC complex presented on pDC2. T cells rendered anergic lost IL-2 production but produced IFN-gamma and IL-10 upon stimulation. The pDC2-induced unresponsiveness was completely or partially reversible when a high concentration of exogenous IL-2 was added in the secondary cultures. Autoreactive CD4(+) T cell clones specific for topoisomerase I derived from a patient with scleroderma were also rendered anergic after co-culture with topoisomerase I-pulsed autologous pDC2,resulting in failure to proliferate or provide help to B cells. These results suggest that pDC2 are involved in maintenance of peripheral T cell tolerance and have potential for use in the suppression of pathogenic T cell responses in autoimmune diseases and organ transplantation.

Autoantigens↗
PubMed2001

A glycomic approach to the identification and characterization of glycoprotein function in cells transfected with glycosyltransferase genes.

The transfection of glycoprotein glycosyltransferase genes into cells leads to modification of both the structure and function of the glycoproteins and as a result, changes in glycome patterns. N-glycan branching enzymes hold some promise as a model system for the identification of glycome patterns. Both N-acetylglucosaminyltransferase III and alpha 1-6 fucosyltransferase are typical glycosyltransferases, which are involved in the branching of N-glycans. The resulting enzymatic products, bisecting N-GlcNAc and alpha 1-6 fucose residues, are no longer modified by other glycosyltransferases and it is a relatively simple task to identify their modification by means of lectins. In this review, the glycome patterns of glycosyltransferase gene transfectants and the non-transfectants were compared by two-dimensional gel electrophoresis and lectin staining, and the biological significance of the two genes are described. Analyses of glycome patterns by transfecting glycosyltransferase genes will lead to new fields of study in the area of postgenome research.

Animals↗
PubMed2001

Comparative localization of Dax-1 and Ad4BP/SF-1 during development of the hypothalamic-pituitary-gonadal axis suggests their closely related and distinct functions.

Two nuclear receptors, Ad4BP/SF-1 and Dax-1, are essential regulators for development and function of the mammalian reproductive system. Similarity in expression sites, such as adrenal glands, gonads, pituitary, and hypothalamus, suggests a functional interaction, and the phenotype similarities were manifested in Ad4BP/SF-1-deficient mice and in cases of natural human mutations of Dax-1. In this study, quantitative reverse transcriptase polymerase chain reaction analyses revealed that expression profiles of Dax-1 in embryonic gonads are different between the two sexes and also from those of Ad4BP/SF-1. Immunohistochemical analyses clarified the spatial and temporal expressions of the Dax-1 protein during development of tissues composing the hypothalamic-pituitary-gonadal axis. During gonadal development, Dax-1 occurred after Ad4BP/SF-1 exhibiting a sexually dimorphic expression pattern at indifferent stages, indicating a possibility of Dax-1 involvement in earliest sex differentiation. When cord formation begins in the testis at embryonic day 12.5 (E12.5), Dax-1 was expressed strongly in Sertoli cells, but its expression level markedly decreased in Sertoli cells and increased in interstitial cells between E13.5 and E17.5. In the female, Dax-1 was strongly expressed in the entire ovarian primordium from E12.5 until E14.5, and then its expression level was decreased and limited to cells near the surface epithelium between E17.5 and postnatal day 0 (P0). During postnatal development of the testis, the variable staining of Dax-1 in Sertoli cells was detected as early as P7 and Dax-1-expressing Leydig cells became rare. In the postnatal ovary, Dax-1 expression was detected in granulosa cells with variable staining intensity, and occasionally in interstitial cells. During pituitary organogenesis, Dax-1 but not Ad4BP/SF-1 was expressed in the dorsal part of Rathke's pouch from E9.5. Later in development after E14.5, the distribution of Dax-1 overlapped with that of Ad4BP/SF-1, being restricted to gonadotropic cells in the anterior pituitary. In the ventromedial hypothalamus (VMH), Dax-1 and Ad4BP/SF-1 were mostly colocalized throughout the embryonic and postnatal development. Thus, the coexpression of Dax-1 and Ad4BP/SF-1 indicates their closely related functions in the development of the reproductive system. Furthermore, we noticed the presence of cells that express Dax-1 but not Ad4BP/SF-1, further indicating additional functions of Dax-1 in an Ad4BP/SF-1-independent molecular mechanism.

Animals↗
PubMed2001

Neonatal estrogen exposure inhibits steroidogenesis in the developing rat ovary.

Treatment of newborn female rats with estrogens significantly inhibits the growth and differentiation of the ovary. To understand the molecular mechanism of estrogen action in the induction of abnormal ovary, we examined the expression profiles of steroidogenic factor 1 (SF-1) and several of its target genes in the developing ovaries after neonatal exposure to synthetic estrogen, estradiol benzoate (EB) by using reverse transcriptase polymerase chain reaction, in situ hybridization, and immunohistochemistry. Morphologic examination indicated inhibitory effects of estrogen on the stratification of follicles and development of theca and interstitial gland during postnatal ovarian differentiation. The expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage cytochrome P450 (P450(SCC)), which are both essential for steroid biosynthesis, markedly decreased in theca and interstitial cells throughout the postnatal development of the EB-treated ovary. However, expression of the transcriptional activator of the two genes, SF-1 was unaffected in theca and interstitial cells, although the number of these cells was lower in the EB-treated ovary than in the control ovary. The expression of the estrogen mediator, estrogen receptor-alpha (ER-alpha), diminished specifically in theca cells at P6 and recovered by P14 in the EB-treated ovary. These results indicate that the effect of estrogens is mediated by means of ER-alpha resulting in the down-regulation of StAR and P450(SCC) genes during early postnatal development of the ovary. These results suggest that the abnormal ovarian development by neonatal estrogen treatment is closely correlated with the reduced steroidogenic activity, and the data obtained by using this animal model may account in part the mechanism for aberrant development and function of the ovary in prenatally estrogen-exposed humans.

Animals↗
PubMed2001

Embryogenesis of the dipluran Lepidocampa weberi Oudemans (hexapoda: diplura, campodeidae): formation of dorsal organ and related phenomena.

The developmental changes of embryonic membranes of a dipluran Lepidocampa weberi, with special reference to dorsal organ formation, are described in detail by light, scanning, and transmission electron microscopies. Newly differentiated germ band and serosa secrete the blastodermic cuticle at the entire egg surface beneath the chorion. Soon after, the serosal cells start to move dorsad. All the serosal cells finally concentrate at the dorsal side of the egg and form the dorsal organ. During their concentration, the serosal cells attenuate their cytoplasm to form filaments. The extensive area from which the serosa has receded is occupied by a second embryonic membrane, the amnion, which originates from the embryonic margin. The embryo and newly emerged amnion then secrete three fine cuticular layers, "cuticular lamellae I, II, and III," above which the filaments of the (developing) dorsal organ are situated. With the progression of definitive dorsal closure, the amnion reduces its extension, the dorsal organ is incorporated into the body cavity of the embryo, and the amnion and dorsal organ finally degenerate. The dorsal organ of diplurans is formed by the concentration of whole serosal cells, while that of collembolans is formed by the direct differentiation of a part of serosal cells. However, the dorsal organs of diplurans and collembolans closely resemble each other in major aspects, including that of ultrastructural features, and there is no doubt regarding their homology. The amnion, which has been regarded as being a characteristic of Ectognatha, also develops in the Diplura. This might suggest a closer affinity between the Diplura and Ectognatha than previously believed.

Animals↗
PubMed2001

Successful combination therapy--flunarizine, pentoxifylline, and cholestyramine--for spur cell anemia.

Spur cell anemia, a hemolytic anemia observed in patients with alcoholic cirrhosis, is characterized by unusual erythrocyte morphology and an increased ratio of free cholesterol to phospholipid in the erythrocyte membrane. The prognosis of spur cell anemia is usually extremely poor, however, we describe here a patient with spur cell anemia who was successfully treated with combination therapy consisting of flunarizine, pentoxifylline, and cholestyramine. Initial therapy with flunarizine alone for 6 weeks did not significantly decrease the number of spur cells on peripheral blood smears. So pentoxifylline was added to the regimen. The patient recovered from the anemia, showed remarkable improvement with regard to the hyperbilirubinemia, and the changes were accompanied by a significant decrease in the number of spur cells in peripheral blood smears. To correct the hypercholesterolemia, cholestyramine was added to the regimen, which resulted in a reduction in the serum level of free cholesterol and an increase in the molar ratio of free cholesterol to phospholipid in erythrocyte membrane. However, 6 months later a skin eruption developed that was considered an adverse reaction to the drugs, so the flunarizine and pentoxifylline were discontinued. With cholestyramine therapy alone, the remission of spur cell anemia was maintained for more than 11 months. These observations suggest that non-invasive combination therapy with flunarizine, pentoxifylline, and cholestyramine is effective and valuable in the treatment of patients with spur cell anemia.

Adult↗
PubMed2001

Quantitative evaluation of the enhanced green fluorescent protein displayed on the cell surface of Saccharomyces cerevisiae by fluorometric and confocal laser scanning microscopic analyses.

The number of foreign protein molecules expressed on the cell surface of the budding yeast Saccharomyces cerevisiae by cell surface engineering was quantitatively evaluated using enhanced green fluorescent protein (EGFP). The emission from EGFP on the cell surface was affected by changes in pH. The amount of EGFP on the cell surface, displayed as alpha-agglutinin-fusion protein under control of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) promoter, was determined at the optimum pH of 7.0. The fluorometric analysis and the image analysis by confocal laser scanning microscopy (CLSM) showed a similar number of molecules displayed on the cell surface, demonstrating that 10(4)-10(5) molecules of alpha-agglutinin-fused molecules per cell were expressed. Furthermore, the amount of fluorescent protein expressed on cells harboring a multicopy plasmid was three to four times higher than that on cells harboring the gene integrated into the genome.

Arabidopsis↗
PubMed2001

T-helper (Th)1/Th2 imbalance in patients with previously untreated B-cell diffuse large cell lymphoma.

T-helper (Th)1/Th2 imbalance has been observed in a variety of pathological conditions, including malignant diseases. We evaluated the Th1/Th2 balance in peripheral blood Th cells by means of intracellular cytokine analysis in 19 patients with previously untreated B-cell diffuse large cell lymphoma (DLCL) and in 18 patients with B-cell DLCL who had achieved complete remission (CR) after chemotherapy. The mean percentage of Th2 in CD4 cells in patients with DLCL (5.00 +/- 2.20) and that of Th1 in CD4+ cells in patients in CR (32.42 +/- 11.30) were significantly increased in comparison with those in healthy volunteers, respectively (Th1; 23.02 +/- 9.45, Th2; 3.25 +/- 0.90; P<0.01). The mean ratio of Th1/Th2 was significantly lower in patients with DLCL (4.74 +/- 0.52) than in patients in CR (9.31 +/- 1.06; P<0.01) and in healthy volunteers (7.25 +/- 0.65; P<0.01). We conclude that the Th1/Th2 balance was polarized to Th2 in untreated DLCL patients and to Th1 in patients in CR, which suggests that a Th1/Th2 imbalance could play a role in lymphomagenesis and durable remission.

Adult↗
PubMed2001

Two novel genes encoding SNF-1 related protein kinases from Arabidopsis thaliana: differential accumulation of AtSR1 and AtSR2 transcripts in response to cytokinins and sugars, and phosphorylation of sucrose synthase by AtSR2.

We searched for genes encoding members of the group-3 SNF1-related protein kinase (SnRK3) family in the Arabidopsis thaliana database, and seven independent sequences were identified. Transcripts of two of them were found to accumulate differentially upon treatment with light, cytokinins and sugars. Full-length cDNAs were isolated and designated as AtSR1 and AtSR2; they encode polypeptides of 442 and 429 amino acids with relative molecular masses of 50.3 kDa and 48.2 kDa, respectively. In etiolated seedlings, no transcripts of either gene were observed. However, upon exposure to light or cytokinins, transcripts of AtSR1 but not AtSR2 began to accumulate. The induction with light was greatly reduced in the presence of a cytokinin antagonist, suggesting that cytokinins are involved in light-signaling pathways. In contrast, transcription of AtSR2, but not of AtSR1, was greatly increased by sucrose, as well as glucose and fructose. AtSR2 expressed in E. coli efficiently phosphorylated sucrose synthase in the presence of manganese ions. These results suggest that, although SnRK3 proteins may generally be involved in sugar metabolism, expression of AtSR1 and AtSR2 is differentially and distinctly regulated by various external signals, and AtSR2 may function in the regulation of sucrose synthase by specific phosphorylation.

Amino Acid Sequence↗
PubMed2001

Mucin-producing tumor of the pancreas associated with pyothorax: report of a case.

We report herein the case of a 76-year-old man for whom an invasive mucin-producing tumor of the pancreas (MPTP) was successfully treated by surgery. A cystic lesion of the pancreas had been found by computed tomography (CT) 9 years earlier, 2 years following which suction drainage for left pyothorax had been carried out. A pancreatic cyst fistula to the thorax had subsequently been found during decortication for recurrent pyothorax 2 years later. Methicillin-resistant Staphylococcus aureus was detected in the pleural discharge after the thoracotomy, and thoracic fenestration was performed. A CT scan done 4 years later showed enlargement of the pancreatic cysts and a cystography revealed communication to the duodenum via the main pancreatic duct. Endoscopic retrograde cholangiopancreatography (ERCP) showed dilatation of the main pancreatic duct. The pancreatic cyst fistulated to the stomach and to the fenestrated thorax. Since MPTP was suspected from this clinical course, a distal pancreatectomy, partial gastrectomy, and omentopexy to the thorax were performed. The pathological diagnosis was intraductal papillary-mucinous tumor of the pancreas with a megacyst. While MPTP is recognized as a low-grade malignancy, some cases of invasive disease have been reported. To the best of our knowledge, this is the first case of MPTP associated with pyothorax due to fistula formation.

Aged↗
PubMed2001

Further development of a recombinant feline herpesvirus type 1 expressing the Gag protein of feline immunodeficiency virus.

We have previously reported the construction of a recombinant feline herpesvirus type 1 (FHV-1), designated C7301ddlTK-gag, expressing the Gag precursor protein of feline immunodeficiency virus (FIV). In this study, we report the construction of a further recombinant FHV-1 (ddlTK(gBp)-gag) which carries an FHV-1 gB promoter sequence upstream of the FIV gag gene of C7301ddlTK-gag. Strong expression of the FIV Gag protein by ddlTK(gBp)-gag was confirmed by immunoblot analyses and enzyme-linked immunosorbent assays. Although C7301ddlTK-gag and ddlTK(gBp)-gag failed to induce anti-FIV Gag antibodies in cats, we confirmed the infectivity and stability of these recombinants in cats.

Animals↗
PubMed2001

Importance of thymus to maintain operational tolerance to fully allogeneic cardiac grafts.

BACKGROUND: The effectiveness of donor-specific blood transfusion (DST) before transplantation has been established. Anti-CD4 monoclonal antibody (anti-CD4) augments the ability of DST to induce indefinite prolongation. Therefore, we investigated the importance of thymus to maintain the unresponsiveness to alloantigens. METHODS: CBA mice were pretreated with 0.25 mL of DST or two doses of anti-CD4 before transplantation of a C57BL/10 heart. Some mice were thymectomized. RESULTS: Naive CBA mice rejected C57BL/10 grafts acutely with a median survival time of 7 days. When mice were pretreated with anti-CD4 plus DST 4 weeks before transplantation, all grafts survived indefinitely (>100 days), whereas mice treated with DST alone or anti-CD4 alone rejected acutely (median survival time, 7 and 12 days, respectively). To investigate the importance of thymus, mice pretreated with anti-CD4 plus DST 4 weeks before transplantation were thymectomized or underwent a sham operation 1 day before grafting. Mice with the sham operation accepted grafts indefinitely, whereas thymectomized mice rejected the majority of the grafts (median survival time, 20 days). CONCLUSIONS: The thymus is important in maintaining the operational tolerance induced by anti-CD4 plus DST 4 weeks before grafting.

Adoptive Transfer↗
PubMed2001

PR-39, a proline/arginine-rich antimicrobial peptide, exerts cardioprotective effects in myocardial ischemia-reperfusion.

OBJECTIVE: PR-39, a proline/arginine-rich antimicrobial peptide, has been shown to inhibit the NADPH oxidase activity of polymorphonuclear leukocytes (PMNs) by blocking assembly of this enzyme. We hypothesized that PR-39 could attenuate PMN-induced cardiac dysfunction by suppression of superoxide production. METHODS: We examined the effects of PR-39 in isolated ischemic (20 min) and reperfused (45 min) rat hearts administered PMNs at the onset of reperfusion. RESULTS: PR-39 (4 or 10 microg/ml) given i.v. 30 min prior to ischemia-reperfusion (I-R) significantly improved left ventricular developed pressure (LVDP, P<0.01) and the maximal rate of development of LVDP (i.e. +dP/dt max, P<0.01) compared to I-R hearts obtained from rats given 0.9% NaCl. PR-39-treated PMNs (10 microg/ml) also significantly attenuated cardiac contractile dysfunction after I-R (P<0.01). Superoxide release was significantly reduced (P<0.01) in N-formylmethionyl-leucylphenylalanine stimulated PMNs pretreated with 4 or 10 microg/ml PR-39. PR-39 also significantly attenuated P-selectin expression on the rat coronary microvascular endothelium and CD18 upregulation in rat PMNs. In addition, PR-39 significantly reduced PMN vascular adherence and infiltration into the post-ischemic myocardium. CONCLUSION: These results provide evidence that PR-39 significantly attenuates PMN-induced cardiac contractile dysfunction in the I-R rat heart at least in part via suppression of superoxide release. This cardioprotection occurred both by inhibition of PMN and endothelial NADPH oxidase.

Animals↗
PubMed2001

Measurement of serum digitoxin in patients by radioimmunoassay using specific antiserum.

INTRODUCTION: Digitoxin is used to treat patients with heart failure. METHODS: A radioimmunoassay procedure for the specific determination for digitoxin in serum was developed using the antiserum (antiserum (A)) raised against digitoxin 3'-hemisuccinate-BSA conjugate. RESULTS: The intra- and interassay variability were <10% in the range of 5-100 ng/ml. The specificities of antiserum (A) and the commercial anti-digitoxin antiserum (antiserum (B)) were assessed by cross-reactivity studies with various related compounds. Antiserum (A) was highly specific for digitoxin. Mean digitoxin concentrations in serum samples (n=34) from digitalized patients by RIA using these antisera were 10.0 and 12.4 ng/ml, respectively. CONCLUSION: This RIA using antiserum (A) measure unmetabolized digitoxin and may be applicable for pharmacokinetic studies.

Animals↗