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Takashi Ueda

Publications and source records attributed to Takashi Ueda.

At least 37 records · Page 2Linked to original sources
PubMed2006

[A case of successful treatment with transcatheter arterial embolization for a ruptured aneurysm of the gastroduodenal artery presenting with a hemosuccus pancreaticus].

A 55-year-old male heavy drinker was taken to another hospital because of loss of consciousness. Laboratory data showed anemia and endoscopy of the upper gastrointestinal tract disclosed intraduodenal bleeding from the ampulla of Vater. Further examinations were scheduled. However, three days later, he was given emergency admission to our hospital because of massive rectal bleeding and circulatory shock. Abdominal contrast-enhanced CT showed a pseudoaneurysm in a pseudocyst in the head of the pancreas. Emergency angiography revealed a ruptured pseudoaneurysm of the gastroduodenal artery 15 mm in diameter. He was successfully treated with transcatheter arterial embolization. ERCP demonstrated the pseudocyst communicating from the main pancreatic duct in the pancreatic head. The final diagnosis was ruptured pseudoaneurysm of the gastroduodenal artery into a pseudocyst, presenting with hemosuccus pancreaticus, secondary to chronic pancreatitis.

Ampulla of Vater↗
PubMed2005

Evans blue is a specific antagonist of the human epithelial Na+ channel delta-subunit.

The epithelial Na(+) channel (ENaC) regulates Na(+) homeostasis in cells and across epithelia. Four homologous ENaC subunits (alpha, beta, gamma, and delta) have been isolated in mammals. Combination of alpha-, beta-, and gamma-subunits or delta-, beta-, and gamma-subunits forms fully functional channels. Amiloride is a well known blocker of the ENaC family that inhibits both channel complexes. However, no specific antagonists are currently known that distinguish them. Here, we show that Evans blue, a diagnostic aid for the measurement of blood volume and vascular permeability, inhibits the activity of the delta-subunit expressed in Xenopus oocytes. The inward currents at a holding potential of -60 mV in human ENaCdeltabetagamma-expressing oocytes were inhibited by the application of Evans blue in a concentration-dependent manner with an IC(50) value of 143 muM. Evans blue markedly inhibited the delta-subunit current but did not block the alpha-subunit current. In conclusion, Evans blue is the first known delta-subunit-specific antagonist of ENaC. This finding provides us with a key compound for elucidating the physiological and pathological functions of ENaCdelta in humans and for drug development in the ENaC family.

Animals↗
PubMed2005

Icilin activates the delta-subunit of the human epithelial Na+ channel.

The amiloride-sensitive epithelial Na(+) channel (ENaC) regulates Na(+) homeostasis in cells and across epithelia. Four homologous ENaC subunits (alpha, beta, gamma, and delta) have been isolated in mammals. The chemical activators acting on ENaC, however, are largely unknown. More recently, we have found that capsazepine activates human ENaCdelta (hENaCdelta), which is mainly expressed in the brain. In addition, here we show that icilin, which is a tetrahydropyrimidine-2-one derivative unrelated structurally to capsazepine, markedly enhanced the activity of hENaCdeltabetagamma heteromultimer expressed in Xenopus laevis oocytes. The inward currents at a holding potential of -60 mV in hENaCdeltabetagamma-expressing oocytes were increased by the application of icilin in a concentration-dependent manner with an EC(50) value of 33 microM. The icilin-elicited current was mostly abolished by the addition of 100 microM amiloride or by the removal of external Na(+). Homomeric hENaCdelta was also significantly activated by icilin, whereas hENaCalpha activity was not affected by icilin, and icilin caused a slight inhibition of the hENaCalphabetagamma current. Furthermore, icilin acted together with protons or capsazepine on hENaCdeltabetagamma. These findings identify icilin as a novel chemical activator of ENaCdelta, providing us with a lead compound for drug development in the degenerin/ENaC superfamily.

Amiloride↗
PubMed2005

DRP1A is responsible for vascular continuity synergistically working with VAN3 in Arabidopsis.

In most dicotyledonous plants, vascular tissues in the leaf have a reticulate venation pattern. We have isolated and characterized an Arabidopsis (Arabidopsis thaliana) mutant defective in the vascular network defective mutant, van3. van3 mutants show a discontinuous vascular pattern, and VAN3 is known to encode an ADP-ribosylation-factor-GTPase-activating protein that regulates membrane trafficking in the trans-Golgi network. To elucidate the molecular nature controlling the vein patterning process through membrane trafficking, we searched VAN3-interacting proteins using a yeast (Saccharomyces cerevisiae) two hybrid system. As a result, we isolated the plant Dynamin-Related Protein 1A (DRP1A) as a VAN3 interacting protein. The spatial and temporal expression patterns of DRP1AGUS and VAN3GUS were very similar. The subcellular localization of VAN3 completely overlapped to that of DRP1A. drp1a showed a disconnected vascular network, and the drp1a mutation enhanced the phenotype of vascular discontinuity of the van3 mutant in the drp1a van3 double mutant. Furthermore, the drp1 mutation enhanced the discontinuous vascular pattern of the gnom mutant, which had the same effect as that of the van3 mutation. These results indicate that DRP1 modulates the VAN3 function in vesicle budding from the trans-Golgi network, which regulates vascular formation in Arabidopsis.

ADP-Ribosylation Factors↗
PubMed2005

In situ hybridization evidence for the coexistence of ASIC and TRPV1 within rat single sensory neurons.

The activation of nociceptors by protons plays a crucial role in the initiation and maintenance of acidosis-linked pain. Acid-sensing ion channel (ASIC) and transient receptor potential/vanilloid receptor subtype-1 (TRPV1) encode proton-activated cation channels expressed by nociceptors and the opening of these channels results in nociceptor excitation. Histological relations among ASIC clones and the colocalization of each ASIC subunit and TRPV1 within single sensory neurons were examined on serial sections of rat dorsal root ganglia (DRG) using in situ hybridization histochemistry. ASIC1a transcripts were expressed in 20-25% of the DRG neurons, and most of the neurons had small (<30 microm)-diameter cell bodies. ASIC1b transcripts and ASIC3 transcripts were expressed in approximately 10% and 30-35% of the DRG neurons, respectively, and the greater part of each population was located in small-to-medium (30-50 microm)-diameter cells. The ASIC1a transcripts and ASIC1b transcripts were basically localized in the distinct populations of the DRG neurons, while approximately 20% of the ASIC1a-positive neurons and approximately 10% of the ASIC1b-positive neurons expressed ASIC3 transcripts. TRPV1 transcripts were expressed in 35-40% of the DRG neurons, and most of the TRPV1-positive neurons had small-diameter cell bodies. Intense expression signals for ASIC1a transcripts were detected in 40-45% of the TRPV1-positive neurons. Neurons expressing both ASIC1b and TRPV1 transcripts were barely detected in the DRG. Approximately 30% of the TRPV1-positive neurons expressed ASIC3 transcripts, and the double-labeled neurons were comprised of both small-diameter and medium-diameter cells. Approximately 13% of the TRPV1-positive neurons expressed both ASIC1a and ASIC3 transcripts.

Acid Sensing Ion Channels↗
PubMed2005

VAN3 ARF-GAP-mediated vesicle transport is involved in leaf vascular network formation.

Within the leaf of an angiosperm, the vascular system is constructed in a complex network pattern called venation. The formation of this vein pattern has been widely studied as a paradigm of tissue pattern formation in plants. To elucidate the molecular mechanism controlling the vein patterning process, we previously isolated Arabidopsis mutants van1 to van7, which show a discontinuous vein pattern. Here we report the phenotypic analysis of the van3 mutant in relation to auxin signaling and polar transport, and the molecular characterization of the VAN3 gene and protein. Double mutant analyses with pin1, emb30-7/gn and mp, and physiological analyses using the auxin-inducible marker DR5::GUS and an auxin transport inhibitor indicated that VAN3 may be involved in auxin signal transduction, but not in polar auxin transport. Positional cloning identified VAN3 as a gene that encodes an adenosine diphosphate (ADP)-ribosylation factor-guanosine triphosphatase (GTPase) activating protein (ARF-GAP). It resembles animal ACAPs and contains four domains: a BAR (BIN/amphiphysin/RVS) domain, a pleckstrin homology (PH) domain, an ARF-GAP domain and an ankyrin (ANK)-repeat domain. Recombinant VAN3 protein showed GTPase-activating activity and a specific affinity for phosphatidylinositols. This protein can self-associate through the N-terminal BAR domain in the yeast two-hybrid system. Subcellular localization analysis by double staining for Venus-tagged VAN3 and several green-fluorescent-protein-tagged intracellular markers indicated that VAN3 is located in a subpopulation of the trans-Golgi network (TGN). Our results indicate that the expression of this gene is induced by auxin and positively regulated by VAN3 itself, and that a specific ACAP type of ARF-GAP functions in vein pattern formation by regulating auxin signaling via a TGN-mediated vesicle transport system.

ADP-Ribosylation Factors↗
PubMed2005

No mortality among 100 consecutive pancreaticoduodenectomies in a middle-volume center.

Mortality rate following pancreaticoduodenectomy has markedly decreased in high-volume centers. We achieved zero mortality among 100 pancreaticoduodenectomies in a middle-volume center. The purpose of this study was to review our experience and analyze factors contributing to the zero mortality. Patient backgrounds, intraoperative variables, postoperative complications, and surgical, radiologic, and other medical interventions for the complications were retrospectively analyzed for 100 consecutive pancreaticoduodenectomies for malignant or benign disease. The mean age of the patients was 63 years. Altogether, 59 patients had preoperative co-morbidity, and 35 had a past history of abdominal surgery. The median operating time and blood loss were 525 minutes and 1215 ml, respectively. Postoperative complications occurred in 42 patients. The most frequent complication was pancreatic stump leak (n = 12), but no life-threatening pancreatic anastomotic leak occurred. This may result from the duct invagination anastomosis applied to 67 pancreases with a small duct. Serious complications were seen in six patients; two patients required surgical intervention, but four were successfully treated with the help of interventional radiologists or internists. Radiologic intervention was applied to 13 patients: drainage of an intraabdominal abscess/collection and vascular intervention. In addition to advances in surgical techniques to reduce local complications, particularly pancreatic anastomotic leak, intimate collaboration with experienced interventional radiologists and internists allows zero mortality even in middle-volume centers.

Adult↗
PubMed2005

Actin-based motility of endosomes is linked to the polar tip growth of root hairs.

Plant tip growth has been recognized as an actin-based cellular process requiring targeted exocytosis and compensatory endocytosis to occur at the growth cone. However, the identity of subcellular compartments involved in polarized membrane trafficking pathways remains enigmatic in plants. Here we characterize endosomal compartments in tip-growing root hair cells. We demonstrate their presence at the growing tip and differential distribution upon cessation of tip growth. We also show that both the presence of endosomes as well as their rapid movements within the tip region depends on an intact actin cytoskeleton and involves actin polymerization. In conclusion, actin-propelled endosomal motility is tightly linked to the polar tip growth of root hairs.

Actins↗
PubMed2005

Biochemical and molecular characterization of a periplasmic hydrolase for oxidized polyvinyl alcohol from Sphingomonas sp. strain 113P3.

Oxidized polyvinyl alcohol hydrolase (OPH) and polyvinyl alcohol dehydrogenase were found to be constitutively present in the periplasm of Sphingomonas sp. strain 113P3 (formerly Pseudomonas sp. 113P3). The OPH was purified to homogeneity with a yield of 40 % and a 5.9-fold increase in specific activity. The enzyme was a homodimer consisting of 35 kDa subunits. Its activity was inhibited by PMSF, Hg(2+) and Zn(2+). The enzyme hydrolysed oxidized polyvinyl alcohol (oxidized PVA) and p-nitrophenyl acetate (PNPA), but did not hydrolyse any of the mono- or diketones tested. K(m) and V(max) values for oxidized PVA and PNPA were 0.2 and 0.3 mM, and 0.1 and 3.4 micromol min(-1) mg(-1), respectively. The gene for OPH was cloned and sequenced. Sequencing analysis revealed that the open reading frame consisted of 1095 bp, corresponding to a protein of 364 amino acids residues, encoding a signal peptide and a mature protein of 34 and 330 amino acids residues, respectively. The presence of a serine-hydrolase motif (a lipase box; Gly-X-Ser-X-Gly) strongly suggested that the enzyme belongs to the serine-hydrolase family. The protein exhibited homology with OPH of the Pseudomonas sp. strain VM15C (63 % identity) and the polyhydroxybutyrate depolymerases from Mesorhizobium loti, Rhizobium sp. and Sinorhizobium meliloti (29-32 % identity). The oph gene was expressed in Escherichia coli under the control of the lac promoter. The recombinant protein had the same molecular mass and N-terminal amino acid sequence as the purified OPH from strain 113P3.

Alcohol Oxidoreductases↗
PubMed2005

Effect of benzalkonium chloride on transscleral drug delivery.

PURPOSE: To investigate the effect and safety of benzalkonium chloride on transscleral drug delivery in the rabbit after continuous intrascleral administration. METHODS: Betamethasone 21-phosphate (BP) aqueous solutions, with or without benzalkonium chloride (BAK), were continuously administered to albino rabbit sclera with an osmotic pump for 1 week. The BP concentrations in the aqueous humor, vitreous, and retina-choroid were measured by high-performance liquid chromatography (HPLC). To investigate the effect of BAK on scleral permeability of BP in vitro, penetration of BP aqueous solution with or without BAK across the rabbit sclera was evaluated using a two-chamber Ussing apparatus. To determine the effects of BAK on transscleral delivery of large molecules, 20- and 70-kDa fluorescein isothiocyanate (FITC)-dextran (FD-20 and -70, respectively) aqueous solutions, with or without BAK, were continuously administered to the sclera by an osmotic pump. The intensity of fluorescence in the aqueous humor, vitreous, and retina-choroid was measured by fluorescence spectrophotometry at 1 week after implantation of the pump. The retinal toxicity of BAK was evaluated electrophysiologically and histologically. RESULTS: BAK increased concentrations of BP in the vitreous and retina-choroid compared with the control. BP was not detected in the aqueous humor. In the in vitro study, BAK did not increase the scleral permeability of BP. In the retina-choroid, BAK significantly increased concentrations of FD-20 but did not increase those of FD-70. The addition of BAK did not increase concentrations of FD-20 or -70 in the vitreous. No substantial toxic reactions were observed in the retina in electrophysiological or histologic examinations after the addition of BAK. CONCLUSIONS: The results of this study demonstrate that BAK may improve the ocular penetration of a drug in a transscleral drug delivery system without producing toxic reactions.

Animals↗
PubMed2005

Japanese normative set of 359 pictures.

This study provides Japanese normative measures for 359 line drawings, including 260 pictures (44 redrawn) taken from Snodgrass and Vanderwart (1980). The pictures have been standardized on voice key naming times, name agreement, age of acquisition, and familiarity. The data were compared with American, Spanish, French, and Icelandic samples reported in previous studies. In general, the correlations between variables in the present study and those in the other studies were relatively high, except for name agreement. Naming times were predicted in multiple regression analyses by name agreement. The full set of the norms and the new pictures may be downloaded from www.psychonomic.org/archive/.

Cognition↗
PubMed2004

Resection of the colon simultaneously with pancreaticoduodenectomy for tumors of the pancreas and periampullary region: short-term and long-term results.

Simultaneous resection of the colon with pancreaticoduodenectomy (PD) is occasionally inevitable to accomplish curative resection in instances when a periampullary tumor involves the mesentery of the colon. However, there is little information regarding short- and long-term outcomes of this aggressive surgery. Among 95 consecutive patients who underwent PD for periampullary malignant tumors, 12 had simultaneous resection of the right colon (group 1) and 83 underwent PD alone (group 2). Intraoperative variables, postoperative morbidity and mortality, and the length of the hospital stay were comparatively analyzed. Survival was also compared between the groups in a subset of 36 pancreatic adenocarcinoma patients. Group 1 included more patients with pancreatic cancer, and portal vein resection was more frequently performed, which seemed to be associated with a significantly longer operating time (640 vs. 510 minutes) and increased total blood loss (1965 vs. 1220 ml). However, morbidity and mortality rates did not differ between the groups (50,0% and 0%, respectively, in group 1; 44.6% and 1.2%, respectively, in group 2). The median hospital stays were 67 and 48 days in groups 1 and 2, respectively. In a subset of 36 pancreatic adenocarcinoma patients, the median progression-free survivals were 6 months in both groups 1 and 2; the median overall survivals were 14 months in group 1 and 12 months in group 2. There was no statistically significant difference in survival between the groups. Simultaneous right hemicolectomy with curative intent at the time of PD could thus be performed safely and may offer a survival benefit even for individuals who have advanced pancreatic cancers with involvement of the transverse mesocolon.

Adenocarcinoma↗
PubMed2004

Capsazepine is a novel activator of the delta subunit of the human epithelial Na+ channel.

The amiloride-sensitive epithelial Na+ channel (ENaC) regulates Na+ homeostasis into cells and across epithelia. So far, four homologous subunits of mammalian ENaC have been isolated and are denoted as alpha, beta, gamma, and delta. The chemical agents acting on ENaC are, however, largely unknown, except for amiloride and benzamil as ENaC inhibitors. In particular, there are no agonists currently known that are selective for ENaCdelta, which is mainly expressed in the brain. Here we demonstrate that capsazepine, a competitive antagonist for transient receptor potential vanilloid subfamily 1, potentiates the activity of human ENaCdeltabetagamma (hENaCdeltabetagamma) heteromultimer expressed in Xenopus oocytes. The inward currents at a holding potential of -60 mV in hENaCdeltabetagamma-expressing oocytes were markedly enhanced by the application of capsazepine (> or =1 microM), and the capsazepine-induced current was mostly abolished by the addition of 100 microM amiloride. The stimulatory effects of capsazepine on the inward current were concentration-dependent with an EC50 value of 8 microM. Neither the application of other vanilloid compounds (capsaicin, resiniferatoxin, and olvanil) nor a structurally related compound (dopamine) modulated the inward current. Although hENaCdelta homomer was also significantly activated by capsazepine, unexpectedly, capsazepine had no effect on hENaCalpha and caused a slight decrease on the hENaCalphabetagamma current. In conclusion, capsazepine acts on ENaCdelta and acts together with protons. Other vanilloids tested do not have any effect. These findings identify capsazepine as the first known chemical activator of ENaCdelta.

Amiloride↗
PubMed2004

Protons activate the delta-subunit of the epithelial Na+ channel in humans.

The amiloride-sensitive epithelial Na(+) channel (ENaC) controls Na(+) transport into cells and across epithelia. So far, four homologous subunits of mammalian ENaC have been isolated and are denoted as alpha, beta, gamma, and delta. ENaCdelta can associate with beta and gamma subunits and generate a constitutive current that is 2 orders of magnitude larger than that of homomeric ENaCdelta. However, the distribution pattern of ENaCdelta is not consistent with that of the beta and gamma subunits. ENaCdelta is expressed mainly in the brain in contrast to beta and gamma subunits, which are expressed in non-neuronal tissues. To explain this discrepancy, we searched for novel functional properties of homomeric ENaCdelta and investigated the detailed tissue distribution in humans. When human ENaCdelta was expressed in Xenopus oocytes and Chinese hamster ovary cells, a reduction of extracellular pH activated this channel (half-maximal pH for an activation of 5.0), and the acid-induced current was abolished by amiloride. The most striking finding was that the desensitization of the acid-evoked current was much slower (by approximately 10% 120 s later), dissociating from the kinetics of acid-sensing ion channels in the degenerin/epithelial Na(+) channel family, which were rapidly desensitized during acidification. RNA dot-blot analyses showed that ENaCdelta mRNA was widely distributed throughout the brain and was also expressed in the heart, kidney, and pancreas in humans. Northern blotting confirmed that ENaCdelta was expressed in the cerebellum and the hippocampus. In conclusion, human ENaCdelta activity is regulated by protons, indicating that it may contribute to the pH sensation and/or pH regulation in the human brain.

Animals↗