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Ryo Takahashi

Publications and source records attributed to Ryo Takahashi.

15 recordsLinked to original sources
PubMed2006

NK cells and gamma delta+ T cells are phenotypically and functionally defective due to preferential apoptosis in patients with atopic dermatitis.

Innate immune cells mediate a first line of defense against pathogens and determine the nature of subsequent acquired immune responses, mainly by producing profound amounts of cytokines. Given these diverse tasks, it is predictable that defective NK and gammadelta(+) T cell responses could be the underlying mechanism for the immunological alterations observed in atopic dermatitis (AD). Indeed, the frequencies of circulating NK cells and gammadelta(+) T cells were profoundly reduced in AD patients. They also displayed a defective ability to sustain TNF-alpha and IFN-gamma, but not IL-4, production after in vitro stimulation, and the defect was restricted to innate immune cells. Surprisingly, on the depletion of CD14(+) monocytes, this selective impairment of TNF-alpha and IFN-gamma production was restored to levels comparable to that observed in controls. Release of IL-10 from monocytes was not a major mechanism of the NK and gammadelta(+) T cell dysfunction. Apoptosis as revealed by annexin V binding, was preferentially observed in NK and gammadelta(+) T cells from AD patients when stimulated in the presence of monocytes, and depletion of monocytes significantly protected these cells from apoptotic cell death. Preferential apoptosis of NK cells by activated monocytes in AD patients was cell-contact-dependent. These results indicate that, once NK and gammadelta(+) T cells in AD patients are in immediate contact with activated monocytes, these cells are specifically targeted for apoptosis, leading to the reduced type 1 cytokine production, thereby directing subsequent acquired immune responses toward a type-2 pattern and increasing susceptibility to infection.

Adult↗
PubMed2006

DRD2/DARPP-32 expression correlates with lymph node metastasis and tumor progression in patients with esophageal squamous cell carcinoma.

BACKGROUND: Dopamine receptors (DRs) are members of seven transmembrane domain trimeric guanosine 5'-triphosphate (GTP)-binding protein-coupled receptor family. Through dopamine receptor activation, dopamine plays a significant role in regulating gene expression, such as induced tumor cell migration. MATERIALS AND METHODS: We investigated DRD1 and DRD2 expressions in patients with esophageal squamous cell carcinoma (ESCC) for immunohistochemistry and analyzed differences between DRD1, DRD2, and DARPP-32 expressions of clinicopathological features in 122 patients with ESCC. RESULTS: DRD1 immunostaining correlated with the pathologic grade (P = 0.0127), and DRD2 immunostaining correlated with the pathologic stage (P = 0.0432) and pN classification (P = 0.0112). A significant correlation was found between DRD1 and DRD2 expression (P = 0.0292). However, no correlation was observed between DRD1/DRD2 expression and DARPP-32 expression (P = 0.4555 and 0.4774, respectively). No correlation was observed between the DRD1/DRD2 expression and patient prognosis. To find the cooperative role between DRD1, DRD2, and DARPP-32 expressions, patients were classified into the different groups. In the DRD2/DARPP-32 combination, the (+/-) group was significantly correlated with pathologic stage (P = 0.0006), lymph node metastasis (P = 0.0001), pT (P = 0.0287), and tumor size (P = 0.0202). Moreover, patients with this combination showed a lower survival rate compared with the other three groups (P = 0.0287). CONCLUSIONS: We conclude that DRD2/DARPP-32 expression is associated with tumor progression and that DRD2/DARPP-32 expressions may help predict prognosis in patients with ESCC.

Adult↗
PubMed2006

The gefitinib-sensitizing mutant epidermal growth factor receptor enables transformation of a mouse fibroblast cell line.

A specific inhibitor of the Epidermal Growth Factor Receptor (EGFR), Gefitinib, displays significant antitumor effects against non-small cell lung cancers (NSCLC) that express EGFR with mutations in their tyrosine kinase domain. Although previous reports have already demonstrated that oncogenic transformation can be induced by some mutant EGFR forms, the precise differences between mutant and wild-type EGFR in terms of mechanisms of transformation have not been fully elucidated. We show here that a murine fibroblast cell line, NR6 becomes transformed by an expression level of the mutant EGFR form lacking E746-A750 that is far less than that needed with transfected wild-type EGFR. However, the mutant EGFR was unable to transform NR6 in a ligand-independent manner, as was seen with the wild-type EGFR. The consequent biological features after transformation, including DNA synthesis or cell cycle progression and biochemical characteristics such as MAPK activation mediated by the mutant EGFR are comparable and equivalent to those mediated by wild-type EGFR. These data suggest that the mutant EGFR possesses greater ligand-dependent transformation when compared with wild-type EGFR, although the exact mechanisms to account for this characteristic remain to be defined.

Animals↗
PubMed2006

Non-steroidal anti-inflammatory drugs selectively inhibit cytokine production by NK cells and gamma delta T cells.

Non-steroidal anti-inflammatory drugs (NSAIDs) are known to be risk factors for a systemic inflammatory syndrome in viral infections. Innate immune cells are likely to represent the preferential targets for the deleterious effects of NSAIDs in patients with viral infections. We therefore examined whether various classes of NSAIDs could selectively inhibit cytokine production by innate immune cells. NSAIDs selectively inhibited interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha production by natural killer (NK) and gammadelta T cells with each NSAID displaying its own unique pattern of inhibition, while sparing that by acquired immune cells. These inhibitions were independent on cyclooxygenase inhibition. These NSAIDs directly inhibited the cytokine production by the purified gammadelta T-cell population without involving other cell populations. The selective inhibition of the early generation of IFN-gamma and TNF-alpha from NK and gammadelta T cells by NSAIDs may serve to drive the subsequent acquired immune responses towards a Th2 phenotype, leading to the aggravation of allergic symptoms. Our results provide a mechanism to explain the deleterious effects of NSAIDs on clinical symptoms of viral infections and allergic diseases and suggest more targeted use depending on the type of disease.

Adult↗
PubMed2005

Pigment epithelium-derived factor gene therapy inhibits human pancreatic cancer in mice.

PURPOSE: Pigment epithelium-derived factor (PEDF), which has recently been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, is also expressed in the pancreas. Previously, we have screened the expression of PEDF by immunohistochemical analysis and showed that low expression of PEDF is associated with increased risk of hepatic metastasis and short survival. The purpose of this study was to investigate whether PEDF gene is a potent tumor suppressor and a potential candidate for cancer gene therapy. EXPERIMENTAL DESIGN: We investigated both in vitro and in vivo growth characteristics of human pancreatic adenocarcinoma cell lines that were stably transfected to overexpress human PEDF and therapeutic effects of lentivirus-based vectors expressing PEDF on tumor growth in murine s.c. tumor model. RESULTS: We discovered that cells secreted PEDF protein in the media and this exhibited strong inhibitory effects on proliferation and migration of human umbilical vein endothelial cells. The size of PEDF-overexpressing pancreatic adenocarcinoma tumors was significantly smaller than that of control tumors in s.c. tumor models. Moreover, the growth of PEDF-overexpressing pancreatic adenocarcinoma cells was significantly suppressed in comparison with control cells in peritoneal metastasis models. In gene transfer models, intratumoral injection of a lentivirus vector encoding PEDF (LV-PEDF) caused significant inhibition of tumor growth. The antitumor effect observed after treatment with LV-PEDF was associated with decreased microvessel density in tumors. CONCLUSION: Our data suggest that PEDF may exert a biological effect on tumor angiogenesis and PEDF gene therapy may provide a new approach for treatment of pancreatic adenocarcinoma.

Adenocarcinoma↗
PubMed2005

Spontaneous rupture of adrenal pheochromocytoma: review and analysis of prognostic factors.

BACKGROUND AND OBJECTIVES: Because of its rarity, the clinical characteristics of the manifestation of a ruptured pheochromocytoma and factors influencing on treatment outcomes in patients are still unclear. METHODS: A comprehensive MEDLINE review of the literature on pheochromocytomas, rupture and hemorrhage was performed. Based on the review and one additional case of our hospital, statistical analysis was undertaken to analyze the association of clinical outcome with clinical presentation, preoperative diagnosis, and treatment modality. RESULTS: We identified 49 other cases of hemorrhagic pheochromocytoma in the literature. After our case was added, a review of all 50 cases revealed that 17 of 38 that could not undergo adequately prepared (elective) surgery died, while all 12 patients who underwent elective surgery survived (P = 0.004). An accurate preoperative diagnosis of pheochromocytoma was associated with elective surgery (P < 0.0001), and hemodynamic instability (shock status) was a significant factor for a failed diagnosis and inadequate management, resulting in a poor prognosis (P = 0.023). CONCLUSIONS: Although it is a very rare condition, physicians should be aware that a pheochromocytoma can bleed and present acutely in the abdomen with shock; an accurate diagnosis and adequately prepared surgical removal are important for a good postoperative prognosis.

Adolescent↗
PubMed2004

Expression of pigment epithelium-derived factor decreases liver metastasis and correlates with favorable prognosis for patients with ductal pancreatic adenocarcinoma.

Pigment epithelium-derived factor (PEDF) is expressed in several normal organs and identified as an inhibitor of neovascularization. In the present study, we screened the expression of PEDF immunohistochemically and investigated its correlation with clinicopathological features in patients who underwent surgery for ductal pancreatic adenocarcinoma. Of the 80 patients, 22 cases (27.5%) were positive for PEDF. A significant association was found between the PEDF expression and low microvessel density (P = 0.0003). No correlation was found between PEDF expression and age, gender, depth of invasion, tumor diameter, lymphatic invasion, venous, invasion or histopathological grading. The patients in pathological stage II had a significantly higher incidence of PEDF-positive expression than those in pathological stage III or IVA (P = 0.0418). PEDF immunoreactivity was inversely associated with liver metastasis (P = 0.0422). The survival of patients that were PEDF positive was significantly longer than that of those with negative expression (P = 0.0026). Multivariate analysis using the Cox regression model indicated that PEDF-positive expression was an independent favorable prognostic factor (risk ratio, 0.394; P = 0.0016). We conclude that PEDF expression suggests a more favorable prognosis than in patients whose carcinomas lack PEDF expression.

Adult↗
PubMed2004

Subcellular localization and regulation of hypoxia-inducible factor-2alpha in vascular endothelial cells.

The hypoxia-inducible factors 1alpha (HIF-1alpha) and 2alpha (HIF-2alpha) have extensive structural homology and have been identified as transcription factors that mediate hypoxia-inducible gene expression through hypoxia-responsive element (HRE). They play critical roles not only in normal development, but also in tumor progression. Endothelial cells (EC) express both HIF-1alpha and -2alpha. In this study, we examined the subcellular localization of HIF-1alpha and -2alpha in bovine arterial EC (BAEC) by immunoblotting and immunocytostaining analysis and found that even under normoxic conditions, as with its heterodimeric partner ARNT, HIF-2alpha was stable, and was localized in the nucleus of BAEC differently than HIF-1alpha. HIF-2alpha might be regulated by a different mechanism than HIF-1alpha and might mediate the expression of some EC-specific genes under normoxic conditions. We further found that cardiovascular helix-loop-helix factor (CHF) 2, which had been identified as an ARNT-interacting protein, was expressed in BAEC and suppressed HRE-dependent gene expression both under normoxia and hypoxia. CHF2 might be one of the key regulators of HIF-2alpha-mediated gene expression in normoxic EC.

Amino Acid Sequence↗
PubMed2004

Selective formation of stable triplexes including a TA or a CG interrupting site with new bicyclic nucleoside analogues (WNA).

Triplex-forming oligonucleotides (TFOs) are potential DNA-targeting molecules and would become powerful tools for genomic research. As the stabilization of the TFO is partially provided by hydrogen bonds to purine bases, the most stable triplexes form with homopurine/homopyrimidine sequences, and a pyrimidine base in the purine strand of the duplex interrupts triplex formation. If a TFO can recognize sequences including such an interrupting site, the target regions in the genome would be expanded to a greater extent. However, this problem has not been generally solved despite extensive studies. We have previously reported a new base analogue (WNA) constructed of three parts, a benzene ring, a heterocyclic ring, and a bicyclic skeleton to hold these two parts. In this study, we have further investigated modification of WNA systematically and determined two useful WNA analogues, WNA-beta T and WNA-beta C, for selective stabilization of triplexes at a TA and a CG interrupting site, respectively. The triplexes with WNA analogues have exhibited an interesting property in that they are more stable than natural-type triplexes even at low Mg(2+) concentration. From comparison of the results with H-WNA-beta T lacking benzene and those with WNA-H without thymine, it has been suggested that benzene is a major contributor for triplex stability and thymine provides selectivity. Thus, it has been successfully demonstrated that WNA-beta T/TA and WNA-beta C/CG combinations may expand triplex recognition codes in addition to the natural A/AT and G/GC base triplet codes. The results of this study will provide useful information for the design of new WNA analogues to overcome inherent problems for further expansion of triplex recognition codes.

Base Pairing↗
PubMed2003

In vitro differentiation from naive to mature E-selectin binding CD4 T cells: acquisition of skin-homing properties occurs independently of cutaneous lymphocyte antigen expression.

We previously showed that skin-homing CD4 T cells in peripheral blood can be subdivided into three populations on the basis of the expression pattern of the cutaneous lymphocyte Ag (CLA) and fucosyltransferase VII (FucT-VII): FucT-VII(+)CLA(-), FucT-VII(+)CLA(+), and FucT-VII(-)CLA(+). In view of the known late appearance of CLA during T cell differentiation, T cells programmed to attain skin-homing properties may start to generate E-selectin-binding epitopes at early stages of differentiation before induction of CLA expression. To this end, the in vitro differentiation from naive to CLA(+) memory T cells was followed after activation with anti-CD3 mAb. Here we demonstrate that naive skin-homing CD4 T cell precursors undergo a linear differentiation process from the FucT-VII(+)CLA(-) phenotype to the FucT-VII(+)CLA(+) phenotype and eventually to the FucT-VII(-)CLA(+) phenotype. The appearance of the FucT-VII(+)CLA(-) subset coincided with or could be immediately followed by the generation of E-selectin binding epitopes, and even after E-selectin-binding epitopes were no longer detectable, CLA remained expressed for prolonged periods of time, suggesting that induction of functional E-selectin ligands depends primarily on the expression of FucT-VII, but not CLA. Immunofluorescence and confocal microscopy studies of these T cells confirm that most E-selectin ligands were found independently of CLA expression.

Adult↗
PubMed2003

Solubilization of fullerene into water with fluoroalkyl end-capped amphiphilic oligomers-novel fluorescence properties.

Solubilization of fullerene into water was studied by the use of fluoroalkyl end-capped acryloylmorpholine oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers. In these fluorinated oligomers, fluoroalkyl end-capped acryloylmorpholine oligomers were more effective in solubilizing fullerene into water. Interestingly, the aqueous solutions of fullerene were applicable to fluorescence analyses.

Acrylamides↗
PubMed2002

Selective formation of non-natural type triplexes containing TA interrupting sites with the TFO incorporating W-shape nucleic acid (WNA) analogs.

Novel nucleoside analogs have been desired for selective formation of non-natural type triplexes containing TA or CG interrupting sites. We have previously reported that the W-shaped nucleic acid (WNA) would be a useful skeleton to develop new base analog for the formation of non-natural triplexes of antiparallel motif. In this study, we have found that triplex forming oligonucleotide (TFO) incorporating the new WNA analog, WNA-beta T, formed more stable triplex than natural triplex with high selectivity to the TA site. It is also noted that the TFO containing WNA-beta T did not form aggregates at the physiological condition of K+.

Electrophoresis, Polyacrylamide Gel↗