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Biomedical subjects

S Ueda

Publications and source records attributed to S Ueda.

At least 235 records · Page 13Linked to original sources
PubMed1997

Resistance to fas-mediated apoptosis of peripheral T cells in human T lymphocyte virus type I (HTLV-I) transgenic mice with autoimmune arthropathy.

Transgenic mice carrying the env-pX region of human T lymphocyte virus type I (HTLV-I) develop autoimmune arthropathy in high incidence. Adopting the approach that Fas-mediated apoptosis has a critical function in the elimination of self-reactive T cells, we examined the involvement of this apoptosis in the induction of autoimmunity in HTLV-I transgenic mice. Splenic T cells derived from the transgenic mice were more resistant to apoptosis induced by anti-Fas mAb than those of the nontransgenic mice, whereas no appreciable difference in apoptosis was detected for thymocytes from either mouse's type. The resistance of transgenic T cells may be due to Tax coded in the pX region, since Tax mediates the inhibition of anti-Fas- induced apoptosis in mature T cell line, Jurkat. Among the transgenic mice, the extent of the resistance to Fas-mediated apoptosis was further enhanced in transgenic T cells with disease. These results suggest that the escape of self-reactive T cells from Fas-mediated apoptosis in the periphery, is critical for the development of autoimmune arthropathy in HTLV-I transgenic mice.

Animals↗
PubMed1997

Dopaminergic modulation of LTP induction in the dentate gyrus of intact brain.

The effect of the dopamine system on the induction of long-term potentiation (LTP) in the dentate gyrus was studied in anesthetized rats. A subthreshold tetanic train (seven pulses at 100 Hz) given to the perforant pathway, which usually fails to elicit LTP, potentiated a slope of field excitatory postsynaptic potentiation (fEPSP) measured from the hilus of the dentate gyrus when a precursor for catecholamine, L-3,4-dihydroxyphenylalanine (L-DOPA), was administered orally to rats. The increase in the fEPSP slope persisted for at least 60 min. Intraventricular injection of a specific dopamine D1/D5 agonist, SKF38393, mimicked the effect of L-DOPA, suggesting an involvement of D1/D5 receptors in the induction of dentate gyrus LTP. Consistent with this, intraventricular administration of the D1/D5 antagonist SCH23390 resulted in complete inhibition of LTP induction by a longer tetanus (100 pulses at 100 Hz), which usually elicits a robust LTP. Thus, D1/D5 receptor activation appears to modulate LTP induction in vivo.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

Evaluation of learning and memory dysfunction and histological findings in rats with chronic stage contusion and diffuse axonal injury.

We previously reported a modified fluid percussion device capable of consistently producing experimental cortical contusion (CC) and diffuse axonal injury (DAI) in separate groups of rats by lateral and midline fluid percussion, respectively. The purpose of the present study was to compare the differences in learning acquisition and memory retention impairments between these two types of injured rats in the chronic stage using the Morris water maze technique. We also compared the histological differences between these two different types of traumatic brain injury. The results showed a statistically significant difference in learning acquisition impairment between the sham and CC rats and also between the sham and DAI rats. However, a significant difference in memory retention impairment was observed only between the sham and DAI rats. Histologically, the neuronal cell loss of CA3 pyramidal cells in the hippocampus was observed on the ipsilateral side in the CC and bilaterally in DAI. The neuronal cell loss was seen in bilateral entorhinal cortex layer II in DAI, but it was not seen in CC. From these results, we speculate that the marked cell loss in the hippocampus CA3 region in both CC and DAI rats was related to the impairment of spatial learning acquisition. The marked cell loss in entorhinal cortex layer II in DAI rats may be one of the important factors in the impairment of spatial memory retention.

Animals↗
PubMed1997

The CD46 transmembrane domain is required for efficient formation of measles-virus-mediated syncytium.

Two phosphatidylinositol (PI)-anchored versions of a measles virus (MV) receptor membrane cofactor protein (MCP; CD46) were generated by fusing the extracellular domain of MCP to the decay-accelerating factor (DAF; CD55) or its PI anchor. The PI-anchored forms of MCP expressed on Chinese hamster ovary cells, otherwise non-permissive to MV, conferred a smaller MV cytopathic effect than a wild-type MCP, a Ser/Thr-rich domain-deletion mutant and a cytoplasmic tail-deletion mutant of MCP. Therefore the differences in MV receptor properties between the two PI-anchored and three transmembrane forms were investigated. The PI-anchored forms were predominantly expressed on microvilli as in DAF, whereas the other transmembrane forms were found on intracellular membranes. The PI-anchored forms conferred high MV-binding capacity compared with the transmembrane versions. MV replication was, however, severely suppressed in cells expressing the PI-anchored forms, resulting in ineffective syncytium formation. In contrast, cell-to-cell fusion occurred efficiently after co-transfection of cDNA species encoding MV-H. MV-F and any version of MCP. Thus the PI-anchored forms, despite showing sufficient MV binding and cell-to-cell fusion competence together with MV-H and MV-F, mediate inefficient MV entry or replication, which causes severe suppression of the MV cytopathic effect. A biased receptor distribution on microvilli might participate in the selection of a low MV uptake pathway in the PI-anchored forms of MCP. Taken together, the transmembrane portion of MCP is a critical factor for effective virus-cell fusion and the subsequent MV replication.

Animals↗
PubMed1997

Effects of ion channel blockers on rapid postmortem changes in extracellular dopamine and serotonin levels in the rat nucleus accumbens.

In the present study, we used in vivo brain microdialysis to examine the effects of ion channel blockers tetrodotoxin (TTX), EGTA-free Ca2+ and verapamil on rapid postmortem changes in extracellular levels of dopamine (DA), serotonin (5-HT) and their metabolites dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) in the ACC of freely moving rats. Extracellular ACC DA levels decreased following the perfusion of the three ion channel blockers in freely moving rats, and then, at death by cervical dislocation, maximum respective 220-, 60- and 90-fold increases were observed in the extracellular output of DA in animals treated with EGTA, verapamil and TTX, respectively. Also, ACC 5-HT decreased following perfusion with the three blockers in the freely moving rats, and then maximum increases of 80-, 30- and 45-fold in the extracellular output of 5-HT were observed at death in animals treated with EGTA, verapamil and TTX, respectively, compared to the baseline. Cervical dislocation-induced rapid postmortem changes were inhibited markedly by perfusion with CSF containing the CA2+ entry blocker verapamil. These observations suggested that rapid postmortem changes in ACC DA and 5-HT release were associated with the action of calcium ion channels and/or voltage gated channels in the CNS.

Animals↗
PubMed1997

Serotonin activates electrolyte transport via 5-HT2A receptor in rat colonic crypt cells.

The aim of this study was to demonstrate that 5-HT activates electrolyte transport directly via 5-HT2A receptor in rat colonic crypt cells. Patch-clamp whole cell recording was performed in isolated crypts to measure the 5-HT-induced changes in electrogenic K+ and Cl- currents. Superfusing 5-HT (10 microM) in the bath solution increased both K+ and Cl- currents, which were antagonized by the presence of ketanserin (1 microM), a selective 5-HT2A antagonist, in the bath solution. Mesulergine (1 microM) a 5-HT2A and 5-HT2C antagonist, had no inhibitory effect. Strong chelation of the intracellular Ca2+ by 5 mM BAPTA inhibited 5-HT-induced currents. 5-HT also failed to activate K+ and C1- currents in the presence of GDPbetaS (0.5 mM) in the pipette solution. Intracellular administration of GTPgammaS (0.1 mM) mimicked the stimulatory effect of 5-HT, that was inhibited by 5 mM BAPTA. H-7 (0.05 mM), an inhibitor of protein kinase C, A, and G, did not affect the currents. These data indicate that a G protein-coupled pathway is involved in the activation of electrolyte secretion via 5-HT2A receptor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Minimally invasive hepatic resection using laparoscopic surgery and minithoracotomy.

To our knowledge, we introduce a new technique to treat a patient with hepatocellular carcinoma having a main tumor and a small satellite nodule in segments IV and VI, respectively. The liver was laparoscopically mobilized; the dissection line was adequately exposed through a 12-cm anterior thoracic incision. Segment VI was resected without hilar dissection or parenchymal compression. The satellite nodule was coagulated with microwaves. The patient had an uneventful postoperative recovery. This technique potentially alleviates postoperative adhesion and allows a minimally invasive surgery.

Carcinoma, Hepatocellular↗
PubMed1997

Evaluation of metabolic heterogeneity in brain tumors using 1H-chemical shift imaging method.

Seventeen brain tumors were measured by 1H-CSI (chemical shift imaging) in a 1.5 T clinical magnetic resonance scanner. The metabolic peaks obtained were evaluated by two methods. One method was to obtain the percentage of each metabolite relative to the combined choline, creatine and NAA peak areas, and the other method was to obtain a ratio of the tumor to contralateral brain. The percentage of choline (%Cho) and choline ratio increased, and the %NAA and NAA ratio decreased in the gliomas and malignant tumors. In relation to grading, %Cho increased but the choline ratio did not. We believed the reason for this was that there were many foci of microscopic necrosis in the glioma grade IV. Free lipids were observed in most of the high grade gliomas and in a malignant tumor. Lactate increased in higher grade tumors. Meningiomas showed the highest %Cho. Statistical differences between the grades of glioma were not detected because many tumors had heterogeneous tissue. One resolution to this problem was metabolite mapping. Mapping of the percentage of metabolites was suitable because it described the regional metabolic changes and the resulting signal to noise ratio was better than that achieved by other methods of evaluation.

Aspartic Acid↗
PubMed1997

Temporal and spatial expression of an intestinal Na+/PO4 3- cotransporter correlates with epithelial transformation during thyroid hormone-dependent frog metamorphosis.

The amphibian intestine has two morphologically distinct structures during development. Early embryogenesis generates a simple, tube-like intestine in the tadpole whereas after thyroid hormone (T3)-dependent metamorphosis a newly remodeled adult intestine is formed similar to that of higher vertebrates. This change requires a drastic transformation of the epithelial layer We have isolated a Na+/PO4 3- cotransporter gene that may contribute to this transformation. The deduced amino acid sequence of this gene shows a high degree of homology to the mammalian renal Na+/PO4 3- cotransporters, which have little or no expression in organs other than the kidney. The frog gene is highly expressed and regulated by T3 in the intestine with little expression and/or regulation by T3 in most other organs. Its mRNA is restricted to the differentiated epithelial cells both in tadpoles and postmetamorphic frogs. Interestingly, its expression is low in premetamorphic tadpoles, but up-regulated when metamorphosis is initiated by endogenous T3. As the larval epithelium undergoes programmed cell death (apoptosis), the mRNa level drops to a minimum. Subsequently, the gene is reactivated at the tip region of the newly formed adult intestinal folds and a crest-trough polarity of expression is established by the end of metamorphosis. This temporal regulation profile is also reproduced when premetamorphic tadpoles are treated with T3 to induce precocious intestinal remodeling. These results suggest a possible role of the Na+/PO 4 3- cotransporter during metamorphosis and demonstrate that the adult epithelial cell differentiation pattern is established in the direction of crest-to-trough of the intestinal fold, concurrent with the epithelial morphogenic process.

Amino Acid Sequence↗
PubMed1997

Temporal and spatial regulation of a putative transcriptional repressor implicates it as playing a role in thyroid hormone-dependent organ transformation.

Thyroid hormone (T3) induces both larval cell death and adult cell proliferation and differentiation during amphibian metamorphosis. We have previously isolated a bZip transcription factor (TH/bZip) as a T3 response gene in the metamorphosing Xenopus intestine. We demonstrate that the Xenopus TH/bZip gene is a direct T3-response gene and ubiquitously regulated by T3 in tadpoles. Developmental in situ hybridization analyses have shown that TH/bZip gene is regulated in a cell-type-specific manner that correlates with tissue transformation. In particular, it is found to be expressed in the larval intestinal epithelial cells prior to their apoptotic degeneration and in the proliferating adult cell types. However, the gene is repressed again upon adult cell differentiation. This regulation pattern mimics that of the thyroid hormone receptor (TR)beta genes. Since the TH/bZip gene is a direct T3-response gene, such a correlation suggests that TR beta may be involved in the regulation of the TH/bZip gene. More importantly, in situ hybridization reveals a strong spatiotemporal correlation of TH/bZip expression with the tissue-specific remodeling in the intestine, suggesting that TH/bZip gene may participate, depending on the cell types, in both inducing apoptosis and stimulating cell proliferation. A similar role has been reported for the proto-oncogene c-myc, another leucine-zipper-containing transcription factor, in tissue culture cell systems.

Animals↗
PubMed1997

Clinical trial of prophylactic endoscopic variceal ligation for esophageal varices.

Endoscopic variceal ligation is an effective therapy for variceal bleeding, and use of the method has recently been increasing. We evaluated the clinical usefulness of prophylactic endoscopic variceal ligation. Twenty-two patients with enlarged, tortuous varices and "red color signs" were selected. These patients were treated with ligation therapy alone and the varices were eradicated, i.e., reduced to small, straight varices without red color signs. Ligation therapy was withdrawn if the general condition of the patient worsened or if the varices could not be removed by suction. Follow-up endoscopy was performed every 4 months, and another ligation was performed if there were recurrent varices or variceal bleeding. The total reduction rate was 86.4%, and eradication required two sessions of therapy and 30 days of hospitalization on average. Complications included esophageal injury in 1 patient and treatment-induced bleeding in 1 patient; both complications were easily controlled. No variceal bleeding occurred after the eradication. There was no mortality due to gastrointestinal bleeding during the median follow-up period of 346 days. Prophylactic endoscopic variceal ligation made it possible to prevent fatal variceal bleeding with a minimum risk of complications, suggesting that this could be an alternative method for the prevention of first-time variceal bleeding.

Adult↗
PubMed1997

Eradication of minimal residual disease during graft-versus-host reaction induced by abrupt discontinuation of immunosuppression following bone marrow transplantation in a patient with Ph1-ALL.

We observed a patient in whom graft-versus-host disease (GVHD) appeared to induce a positive effect. This 32-year-old male with Philadelphia chromosome-positive acute lymphoblastic leukemia received a bone marrow transplant (BMT) from an HLA-identical sibling donor. We analyzed the bone marrow with the reverse transcriptase-polymerase chain reaction to screen for the minor bcr/abl transcript, which indicates the presence of minimal residual disease (MRD). MRD was present in the pre- and post-transplant phases. There was no evidence of acute GVHD by post-transplant day 45. We abruptly discontinued the immunosuppressive therapy in an attempt to eliminate MRD by inducing an antileukemic reaction during GVHD. GVHD associated with diarrhea and liver dysfunction developed on day 64. On day 105, MRD disappeared and GVHD was treated with prednisolone and cyclosporin. The disappearance of MRD may have been due to the graft-versus-leukemia (GVL) effect mediated by the alloimmune response of donor T lymphocytes. These findings suggest that induction of the GVL effect may be useful for eliminating MRD after BMT in leukemia patients at high risk of recurrence of the disease.

Adult↗
PubMed1997

Multiple EDAS (encephalo-duro-arterio-synangiosis). Additional EDAS using the frontal branch of the superficial temporal artery (STA) and the occipital artery for pediatric moyamoya patients in whom EDAS using the parietal branch of STA was insufficient.

Although parietal EDAS or STA-MCA anastomosis are effective in pediatric moyamoya disease, they do not adequately prevent ischemia in the frontal and occipital lobes. Some additional methods that can prevent ischemia in the frontal and occipital lobes are sometimes needed. We investigated whether EDAS using a frontal branch of the superficial temporal artery (frontal EDAS) or EDAS using the occipital artery (occipital EDAS) is preferable. Frontal or occipital EDAS was performed at 15 sites in seven patients with pediatric moyamoya disease. The outcome was estimated by angiography 3 months later, CT findings 3 months later, neurological findings during the follow up period and perioperative complications. The mean follow up period was 14 +/- 6 months after frontal or occipital EDAS. As results, good revascularization from frontal or occipital EDAS was shown in ten of fourteen surgical sites (71%) in angiography. None of the patients showed deterioration of symptoms after frontal or occipital EDAS during the follow up period. None of the patients developed surgical complications. In conclusion, multiple EDAS using the frontal branch of STA and the occipital artery is an effective and safe method for preventing ischemia in the frontal and occipital lobe in pediatric moyamoya disease.

Blood Flow Velocity↗
PubMed1997

Long-term follow up of a growing skull fracture treated by dura and cranioplasty with artificial dura mater and methylmethacrylate.

We report the long-term follow up of a growing skull fracture treated by duraplasty and cranioplasty with artificial dura mater and methylmethacrylate. The patient had undergone duraplasty and cranioplasty 19 years earlier at the age of 1 year and 11 months old. We examined the growth of the skull and the long-term adaptation between his own skull and methylmethacrylate 19 years after cranioplasty.

Adolescent↗
PubMed1997

Local disturbance of neuronal migration in the S-100beta-retarded mutant mouse.

Homozygotes of a mouse strain with genetic polydactyly (Pdn) show disrupted cortical lamination and a significant decrease of S-100beta-immunoreactive elements in a particular area of the brain. In order to understand the abnormal cortical formation at the cellular level, the migration of cortical neurons and the development of glial cells were studied using bromodeoxyuridine (BrdU), S-100beta, and glial fibrillary acidic protein (GFAP) immunohistochemistry. Homozygous mice (Pdn/Pdn) displayed a variable pattern of abnormalities. Irregular GFAP-positive radial glial cells and disturbance of neuronal migration were found in a circumscribed area of the caudo-dorsal cortex of newborn Pdn mouse. The number of S-100beta-positive cells was reduced in this area. The present results suggest that abnormal cortical lamination closely correlates with disturbance of neuronal migration and abnormalities of glial cells, especially a significant decrease of S-100beta-immunoreactive cells.

Animals↗
PubMed1997

Cultured retinal pericytes stimulate in vitro angiogenesis of endothelial cells through secretion of a fibroblast growth factor-like molecule.

Interaction between cultured endothelial cells (EC) and pericytes (PC) was studied in vitro to clarify the mechanism of diabetic proliferative retinopathy. Conditioned medium (CM) from retinal PC strongly increased the proliferation and moderately stimulated migration of retinal EC. Moreover, CM from PC caused stimulation of angiogenesis of retinal EC and umbilical cord vein EC in vitro at the same extent as basic fibroblast growth factor (bFGF). PC also stimulated angiogenesis by EC in mixed cultures. The angiogenic, proliferative and migration activities in CM from PC were inhibited by an antibody to bFGF. These data suggest that PC play an important role in angiogenesis through secretion of an FGF-like molecule.

Animals↗
PubMed1997

A new balloon-controlled temporary vascular clip.

We devised a temporary clip that is manipulated by inflation or deflation of a balloon. Prior application of this temporary clip to the proximal artery is convenient for controlling distal bleeding during microsurgery.

Arterial Occlusive Diseases↗