Biomedical subjects

T Suda

Publications and source records attributed to T Suda.

At least 37 records · Page 2Linked to original sources

PubMed2001

Cloning of a new aquaporin (AQP10) abundantly expressed in duodenum and jejunum.

A new aquaporin (AQP10) was identified in human small intestine. This gene encoded a 264-amino-acid protein with high sequence identity with AQP3 (53%), 9 (52%), and 7 (43%). These AQPs constitute one subfamily of AQP family that is differentiated from the other subfamily of AQP (AQP0, 1, 2, 4, 5, 6, and 8) by sequence homology. Ribonuclease protection assay and Northern blotting demonstrated almost exclusive expression of AQP10 mRNA in the duodenum and jejunum. In situ hybridization localized it in absorptive jejunal epithelial cells. Xenopus oocytes expressing AQP10 exhibited an increased osmotic water permeability in a mercury-sensitive manner. Although AQP10 belongs to the AQP subfamily, which has been characterized by permeability to water and neutral solutes such as urea and glycerol, it was not permeable to urea nor glycerol. The specific expression of AQP10 suggests its contribution to the water transport in the upper portion of small intestine.

Amino Acid Sequence↗

PubMed2001

Relativistic effects and two-body currents in (H)((-->)e(')p)n using out-of-plane detection.

Measurements of the (2)H((-->)e,e(')p)n reaction were performed with the out-of-plane magnetic spectrometers (OOPS) at the MIT-Bates Linear Accelerator. The longitudinal-transverse, f(LT) and f(')(LT), and the transverse-transverse, f(TT), interference responses at a missing momentum of 210 MeV/c were simultaneously extracted in the dip region at Q2 = 0.15 (GeV/c)(2). In comparison to models of deuteron electrodisintegration, the data clearly reveal strong effects of relativity and final-state interactions and the importance of two-body meson-exchange currents and isobar configurations. We demonstrate that such effects can be disentangled by extracting these responses using the novel out-of-plane technique.

Journal Article↗

PubMed2001

ALCAM (CD166): its role in hematopoietic and endothelial development.

A critical role for the endothelium of yolk sac and dorsal aorta has been shown in embryonic hematopoiesis. A stromal cell line derived from yolk sac, YSCL-72, has been chosen to search for a novel molecule associated with embryonic hematopoiesis. Analysis between YSCL-72 and an adult aorta-derived endothelial cell line, EOMA, demonstrated that activated leukocyte cell adhesion molecule (ALCAM, or CD166) was specifically expressed in YSCL-72 but not in EOMA. Immunohistochemical study showed that ALCAM was expressed in the endothelium of yolk sac and dorsal aorta but not in adult aorta. ALCAM-transfected EOMA cells supported development of hematopoietic progenitor cells compared with vector-transfected EOMA cells, suggesting that ALCAM appeared to be crucial for hematopoiesis. In addition, ALCAM was found to be involved in capillary tube formation and hemangioblast differentiation. Taken together with these findings, ALCAM is highly associated not only with embryonic hematopoiesis but also vasculoangiogenesis.

Activated-Leukocyte Cell Adhesion Molecule↗

PubMed2001

Endomucin is expressed in embryonic dorsal aorta and is able to inhibit cell adhesion.

Recent studies have suggested the existence of progenitors common to hematopoietic and endothelial cells, called hemangioblasts, in, for instance, embryonic dorsal aorta. To identify a membrane-bound or secretory molecule regulating early hematopoiesis, we screened a cDNA library from dorsal aortas of embryonic day (E) 10.5 mice by a signal sequence trap method and obtained a clone encoding a sialoprotein, endomucin-1. Immunohistochemistry revealed that the endomucin-1 transcript was specifically expressed in the endothelial cells of dorsal aorta of E10.5 mouse embryo. Overexpression of endomucin-1 strongly inhibited adhesion and aggregation of cells, including cultured endothelial cells from E10.5 dorsal aorta. These data suggest that endomucin-1 may play a role in detachment of hematopoietic cells from endothelium during early hematopoiesis.

Amino Acid Sequence↗

PubMed2001

Stromal cells expressing ephrin-B2 promote the growth and sprouting of ephrin-B2(+) endothelial cells.

Ephrin-B2 is a transmembrane ligand that is specifically expressed on arterial endothelial cells (ECs) and surrounding cells and interacts with multiple EphB class receptors. Conversely, EphB4, a specific receptor for ephrin-B2, is expressed on venous ECs, and both ephrin-B2 and EphB4 play essential roles in vascular development. The bidirectional signals between EphB4 and ephrin-B2 are thought to be specific for the interaction between arteries and veins and to regulate cell mixing and the making of particular boundaries. However, the molecular mechanism during vasculogenesis and angiogenesis remains unclear. Manipulative functional studies were performed on these proteins in an endothelial cell system. Using in vitro stromal cells (OP9 cells) and a paraaortic splanchnopleura (P-Sp) coculture system, these studies found that the stromal cells expressing ephrin-B2 promoted vascular network formation and ephrin-B2(+) EC proliferation and that they also induced the recruitment and proliferation of alpha-smooth muscle actin (alpha-SMA)-positive cells. Stromal cells expressing EphB4 inhibited vascular network formation, ephrin-B2(+) EC proliferation, and alpha-SMA(+) cell recruitment and proliferation. Thus, these data suggest that ephrin-B2 and EphB4 mediate reciprocal interactions between arterial and venous ECs and surrounding cells to form each characteristic vessel. (Blood. 2001;98:1028-1037)

Animals↗

PubMed2001

Expression of angiopoietin-2 in human glioma cells and its role for angiogenesis.

In highly vascular malignant glioma, glioma cells themselves may express angiogenic factors and induce angiogenesis. Recent studies have shown that novel angiogenic factors, angiopoietin-1 (Ang1) and -2 (Ang2), play important roles in the modulation of vasculogenesis and angiogenesis. In this study, we determined Ang2 mRNA expression in cultured human malignant glioma cells (U105, U251, and U373 MG) by reverse transcriptase-PCR. Western blot analysis and immunocytochemical analysis with antihuman Ang2 antibody revealed that Ang2 protein was expressed and secreted by these cells. Furthermore, hypoxia increased the Ang2 protein level in cultured glioma cells. Serial sections of 32 human glioma tissues (14 glioblastomas, eight anaplastic astrocytomas, seven astrocytomas, and three pilocytic astrocytomas) were immunostained against Ang2, vascular endothelial growth factor, Tie2, von Willebrand factor, and alpha smooth muscle actin. The immunoreactivity of each angiogenic factor was higher in malignant gliomas than in low-grade gliomas. Ang2 protein was detected not only in endothelial cells but also in glioma cells, and its expression was prominent in both the area surrounding the necrosis and the periphery of glioblastomas. In the area surrounding necrosis, Ang2 was highly expressed and tumor vessels showed regression. In the tumor periphery, Ang2 was highly expressed and many small vessels stained positively for von Willebrand factor but not for alpha smooth muscle actin, suggesting angiogenesis. Statistical analysis revealed that the Ang2 expression was negatively correlated with vessel maturation in malignant gliomas and that vascular endothelial growth factor expression was positively correlated with vessel maturation in low-grade gliomas (P < 0.05). These results suggest that glioma cells themselves express Ang2 and that expression may be induced by hypoxic stimulation and may play a crucial role in the vessel maturation, angiogenesis, and vessel regression in malignant glioma.

Adolescent↗

PubMed2001

Correlation between 25-hydroxyvitamin D3 1 alpha-hydroxylase gene expression in alveolar macrophages and the activity of sarcoidosis.

PURPOSE: To demonstrate expression of the 25-hydroxyvitamin D3 1 alpha-hydroxylase (1 alpha-hydroxylase) gene in human alveolar macrophages and measure the correlations among the 1 alpha-hydroxylase mRNA level, the activity of sarcoidosis, and calcium metabolism. SUBJECTS AND METHODS: We examined 7 patients with sarcoidosis and 6 control patients with other pulmonary disorders who underwent bronchoalveolar lavage. Levels of 1 alpha-hydroxylase mRNA were measured by semiquantitative polymerase chain reaction amplification. We measured serum levels of calcium, ionized calcium, parathyroid hormone, calcitriol (1,25-dihydroxyvitamin D3), and 25-hydroxyvitamin D3 to evaluate calcium metabolism. To estimate the activity of sarcoidosis, we measured the cell count, the CD4/CD8 ratio in bronchoalveolar lavage cells, and the serum angiotensin-converting enzyme (ACE) activity. RESULTS: Expression of 1 alpha-hydroxylase was demonstrated in purified human alveolar macrophages. The 1 alpha-hydroxylase mRNA levels in bronchoalveolar lavage cells were fivefold higher in sarcoidosis patients than in control patients (10.8 +/- 3.6 vs. 2.2 +/- 1.4, P <0.003). Among all patients studied, there were significant correlations between the 1 alpha-hydroxylase mRNA level in bronchoalveolar lavage samples and the percentage of alveolar lymphocytes (r = 0.83, P <0.005), the CD4/CD8 ratio (r = 0.77, P <0.02), serum ACE level (r = 0.58, P <0.05), serum ionized calcium level (r = 0.58, P <0.05), and the calcitriol/25-hydroxyvitamin D3 ratio (r = 0.57, P <0.05). In the sarcoidosis patients, a significant correlation was also observed between 1 alpha-hydroxylase mRNA and the percentage of alveolar lymphocytes (r = 0.82, P <0.05). CONCLUSION: There is a correlation between 1 alpha-hydroxylase gene expression in alveolar macrophages with the activity of sarcoidosis and its associated disturbances in calcium metabolism.

Adult↗

PubMed2001

Measurement of the elastic magnetic form factor of (3)He at high momentum transfer.

New electron scattering measurements have been made that extend data on the (3)He elastic magnetic form factor up to Q(2) = 42.6 fm(-2). These new data test theoretical conjectures regarding non-nucleonic effects in the three-body system. The very small cross sections, as low as 10(-40) cm(2)/sr, required the use of a high-pressure cryogenic gas target and a detector system with excellent background rejection capability. No existing theoretical calculation satisfactorily accounts for all the available data.

Journal Article↗

PubMed2001

Fluoxetine reduces L-DOPA-derived extracellular DA in the 6-OHDA-lesioned rat striatum.

We investigated the effect of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), on L-DOPA-derived extracellular dopamine (DA) levels in the striatum of rats with nigrostriatal dopaminergic denervation using in vivo microdialysis. Treatment with fluoxetine (10 mg/kg, i.p.) induced a 41% reduction in the cumulative amount of extracellular DA during 300 min following L-DOPA administration (50 mg/kg, i.p.; p < 0.01). This effect was antagonized by pretreatment with WAY-100635, a potent 5-HT1A antagonist, indicating that this effect of fluoxetine is due to its indirect 5-HT1A agonistic property. These results suggest that SSRIs may impair motor functions in patients with Parkinson's disease by reducing efflux of exogenous L-DOPA-derived DA.

Adrenergic Agents↗

PubMed2001

Localization of recombination activating gene 1/green fluorescent protein (RAG1/GFP) expression in secondary lymphoid organs after immunization with T-dependent antigens in rag1/gfp knockin mice.

Secondary rearrangements of immunoglobulin gene segments that generate a new antibody repertoire in peripheral B cells have been described as receptor revision and occur by as yet unknown mechanisms. To determine the importance of recombination activating gene (RAG) expression in receptor revision, heterozygous rag1/green fluorescent protein (gfp) knockin mice were used to examine the location of RAG1 expression in the germinal centers (GCs) of lymphoid follicles after immunization with a variety of T-cell-dependent antigens. Immunization of rag1/gfp heterozygous mice or rag1 homozygous knockout mice reconstituted with rag1/gfp heterozygous spleen cells caused the down-regulation of RAG1/GFP signal in GCs. Although some RAG1/GFP(+) cells appeared in regions surrounding the peanut agglutinin (PNA)(+)GL-7(+) GC area, RAG1/GFP(+) cells did not accumulate in the central region. In addition, the stimulation of spleen B cells with anti-mu antibody plus interleukin-4 (IL-4) or with anti-CD40 monoclonal antibody plus IL-7 did not induce GFP signals at detectable levels in vitro. These results clearly demonstrate that RAG1 re-expression either does not occur or is at extremely low levels in antigen-driven B cells in GCs of secondary lymphoid follicles, suggesting that other mechanisms may mediate the gene rearrangements observed in receptor revision.

Animals↗

PubMed2001

An oxidized derivative of cholesterol increases the release of soluble vascular cell adhesion molecule-1 from human umbilical vein endothelial cells in culture.

Treatment of human umbilical vein endothelial cells (HUVECs) with 7-ketocholesterol resulted in an increased release of soluble vascular cell adhesion molecule-1 (VCAM-1) into culture medium. 7-Ketocholesterol did not enhance the expression of mRNA for VCAM-1. 7 beta-Hydroxy- or 25-hydroxycholesterol had no effect on soluble VCAM-1 levels. Western blot analysis revealed that soluble VCAM-1, in the conditioned medium of both 7-ketocholesterol-stimulated and control cells, had a molecular size of 100 kDa. Stimulation of the TNF-alpha-treated HUVECs with 7-ketocholesterol further increased the levels of soluble VCAM-1 in the culture medium. Again, 7-ketocholesterol did not affect the VCAM-1 mRNA level, which was enhanced by TNF-alpha. Pretreatment of the cells with tissue inhibitor of membrane metalloproteinase-2 (TIMP-2) completely inhibited the release of VCAM-1 in response to 7-ketocholesterol but TIMP-1 had no effect. Adherence of mononuclear cells to TNF-stimulated HUVEC monolayers was slightly inhibited by 7-ketocholesterol, but this oxysterol did not affect the basal adherence to non-stimulated HUVECs. Immunofluorescent staining of the cells confirmed diffuse perinuclear distribution of VCAM-1 in HUVECs treated with TNF-alpha, but 7-ketocholesterol did not affect the intensity or distribution of immunofluorescence. We conclude that 7-ketocholesterol releases VCAM-1 from the endothelium probably by a proteolytic process.

Blotting, Western↗

PubMed2001

A significant participation of orexin-A, a potent orexigenic peptide, in the preovulatory luteinizing hormone and prolactin surges in the rat.

Orexins are novel hypothalamic peptides which stimulate food intake. In view of the well-known tight connection between the nutritional state and the reproductive function, in this study we examined a possible role of orexin-A in the generation of ovarian steroid-induced luteinizing hormone (LH) and prolactin (PRL) surges in ovariectomized rats. Experiments were performed on both normally-fed and 3-day-fasted rats. Although fasting led to abolition of both LH and PRL surges, intracerebroventricular administration of orexin-A (0.3 and 3.0 nmol) resulted in a dose-dependent recovery of the hormonal surges. In addition, anti-orexin-A antisera given to normally-fed rats completely abrogated the surges of both hormones. These results demonstrate for the first time a significant participation of orexin-A in the preovulatory LH and PRL surges in the rat.

Animals↗

PubMed2001

Agouti-related peptide prevents steroid-induced luteinizing hormone and prolactin surges in female rats.

We studied the effect of Agrp (agouti-related peptide) on LH (luteinizing hormone) and PRL (prolactin) surges in ovariectomized rats primed with estradiol and progesterone. The rats displayed characteristic LH and PRL surges that were completely abolished by starving. Injection of either 1 nmol or 3 nmol Agrp (83-132), a potent antagonist of the orexigenic MC3 and MC4 receptors, completely prevented both the LH and PRL surges. We also investigated the effects of either a single or double injection of anti-Agrp serum to fasted animals, which were without LH and PRL surges. A single injection of the antiserum was without effect, but the rats that received double injection of anti-Agrp serum partially reinstated both the LH and PRL surges. Although the onset of LH and PRL surges was significantly delayed in the double treated group, the highest levels of the surges for both hormones were statistically indistinguishable compared with the control group. These data give a clear indication that endogenous Agrp may be involved in LH and PRL surges during starvation, providing further evidence that the melanocortin system is important for these hormonal surges in female rats.

Agouti-Related Protein↗

PubMed2001

Further evidence for a significant participation of the melanocortin 4 receptor in the preovulatory prolactin surge in the rat.

We previously reported that the melanocortin 4 receptor may play a significant role in mediating the preovulatory surges of luteinizing hormone and prolactin in the rat. In order to confirm this previous finding, in the present study we examined and compared the effects of intracerebroventricular administrations of 1.0 nmol of MT II (a non-selective melanocortin 3 and 4 receptor agonist) and 10 nmol of gamma(1)-melanocyte-stimulating hormone (a selective melanocortin 3 receptor agonist) on luteinizing hormone and prolactin surges in starved, gonadal steroid-primed ovariectomized female rats, which is a model deprived of inherent surges of the two hormones. MT II significantly recovered the surge of prolactin, but not of luteinizing hormone (although a tendency to increase was seen), and gamma(1)-melanocyte-stimulating hormone was without effect on both hormones. This study corroborated our previous report through a different and direct approach that the melanocortin 4 receptor, but not the melanocortin 3 receptor, plays a significant role in mediating the preovulatory prolactin surge in the rat.

Animals↗

PubMed2001

Exogenous clustered neuropilin 1 enhances vasculogenesis and angiogenesis.

Neuropilin 1 (NP-1) is a receptor for vascular endothelial growth factor (VEGF) 165 (VEGF165) and acts as a coreceptor that enhances VEGF165 function through tyrosine kinase VEGF receptor 2 (VEGFR-2). Transgenic overexpression of np-1 results in an excess of capillaries and blood vessels and a malformed heart. Thus, NP-1 may have a key role in vascular development. However, how NP-1 regulates vascular development is not well understood. This study demonstrates how NP-1 can regulate vasculogenesis and angiogenesis in vitro and in vivo. In homozygous np-1 mutant (np-1(-/-)) murine embryos, vascular sprouting was impaired in the central nervous system and pericardium. Para-aortic splanchnopleural mesoderm (P-Sp) explants from np-1(-/-) mice also had vascular defects in vitro. A monomer of soluble NP-1 (NP-1 tagged with Flag epitope) inhibited vascular development in cultured wild-type P-Sp explants by sequestering VEGF165. In contrast, a dimer of soluble NP-1 (NP-1 fused with the Fc part of human IgG) enhanced vascular development in cultured wild-type P-Sp explants. Moreover, the NP-1-Fc rescued the defective vascular development in cultured np-1(-/-) P-Sp explants. A low dose of VEGF alone did not promote phosphorylation of VEGFR-2 on endothelial cells from np-1(-/-) embryos, but simultaneous addition of a low dose of VEGF and NP-1-Fc phosphorylated VEGFR-2 significantly. Moreover, NP-1-Fc rescued the defective vascularity of np-1(-/-) embryos in vivo. These results suggest that a dimer form of soluble NP-1 delivers VEGF165 to VEGFR-2-positive endothelial cells and promotes angiogenesis.

Animals↗

PubMed2001

The molecular basis of osteoclast differentiation and activation.

Osteoclasts develop from haemopoietic cells of the monocyte-macrophage lineage. Osteoblasts or stromal cells are essentially involved in osteoclastogenesis through cell-cell interaction with osteoclast progenitor cells. Recent findings indicate that osteoblasts/stromal cells express osteoclast differentiation factor (ODF, also called RANKL, TRANCE and OPGL) as a membrane-associated factor in response to several osteotropic factors to support osteoclast differentiation. ODF is a new member of the tumour necrosis factor (TNF) ligand family. Osteoclast precursors, which express RANK, a TNF receptor family member, recognize ODF through cell-cell interactions with osteoblasts/stromal cells, and differentiate into osteoclasts in the presence of macrophage colony-stimulating factor (M-CSF). Osteoclastogenesis inhibitory factor (OCIF, also called OPG), is a secreted TNF receptor, which acts as a decoy receptor for ODF. ODF is responsible for inducing not only differentiation, but also activation of osteoclasts. Interleukin 1 alpha (IL-1 alpha) can be substituted for ODF in inducing the activation of osteoclasts. Recently, it was shown that mouse TNF alpha stimulated the differentiation of M-CSF-dependent mouse bone marrow macrophages into osteoclasts in the presence of M-CSF without any help of osteoblasts/stromal cells. Osteoclast formation induced by TNF alpha was inhibited by antibodies against TNF type 1 receptor (TNFR1) or TNFR2, but not by OCIF. Osteoclasts induced by TNF alpha formed resorption pits on dentine slices only in the presence of IL-1 alpha. These results demonstrate that TNF alpha stimulates osteoclast differentiation through a mechanism independent of the ODF-RANK interaction. TNF alpha and IL-1 alpha may play an important role in pathological bone resorption due to inflammation.

Animals↗

PubMed2001

Expression of Fas ligand is an early event in colorectal carcinogenesis.

BACKGROUND AND OBJECTIVES: Fas ligand (FasL) is expressed in many cancers and plays an important role in establishing immunologically privileged environments that allow tumors to escape the host's immune surveillance. We investigate the expression of FasL in human colorectal cancer and colorectal adenoma and elucidate the relationship between FasL expression and the clinicopathological characteristics of colorectal cancers. METHODS: We examined 214 colorectal cancer specimens and 83 colorectal adenoma specimens. Expression of FasL was determined by immunohistochemical staining using a specific monoclonal antibody. We analyzed the relationship between the results of FasL expression and clinicopathological data statistically. RESULTS: FasL expression was detected in 173 (80.8%) of 214 colorectal carcinomas and 34 (40.9%) of 83 colorectal adenomas. The status of FasL expression in colorectal carcinoma was independent of clinicopathological features including tumor stage, histologic grade, lymphatic invasion, venous invasion, lymph node metastasis, liver metastasis, and Dukes stage. In colorectal adenoma, FasL expression was more frequently observed in high-grade atypia than in low-grade atypia (P = 0.05). CONCLUSIONS: FasL expression is commonly observed not only in cancer but also in highly dysplastic tissue. These observations suggest that FasL expression may be an important event in the transformation process leading to adenocarcinoma.

Adenocarcinoma↗

PubMed2001

The membrane-bound but not the soluble form of human Fas ligand is responsible for its inflammatory activity.

The ectopic expression of Fas ligand (FasL/CD95L) in tissues or tumors induces neutrophil infiltration and the destruction of the tissues or the rejection of tumors. It has been suggested that the infiltrated neutrophils are responsible for the latter phenomena. FasL is synthesized as a type II transmembrane protein, and soluble FasL is produced by a proteolytic mechanism from the membrane-bound form. We previously demonstrated that uncleavable membrane-bound FasL of mice induces IL-1 beta release from inflammatory cells, and suggested that the IL-1 beta enhances neutrophil infiltration. However, recent papers reported that human soluble FasL is directly chemoattractive to neutrophils in vitro and proposed that the soluble form of FasL is responsible for its inflammatory activity. Therefore, in this report, we investigated which form is responsible for the inflammatory activities of human FasL. We produced tumor cell lines expressing one or both forms of human FasL. Cells expressing both forms or only the membrane-bound form of FasL induced neutrophil infiltration when transplanted into the peritoneal cavity of syngeneic mice, while cells expressing only the soluble form did not. Purified soluble FasL failed to induce neutrophil infiltration in vivo. IL-1 beta release from inflammatory peritoneal exudate and acceleration of tumor rejection were also mediated by membrane-bound but not soluble FasL. These results indicate that the membrane-bound form of FasL is primarily responsible for its inflammatory activity.

Animals↗