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T Iida

Publications and source records attributed to T Iida.

At least 37 records · Page 2Linked to original sources
PubMed2002

Particle size analysis of radioactive aerosols formed by irradiation of argon using 65 MeV quasi-monoenergetic neutrons.

The size distributions of 38Cl and 39Cl aerosols formed from the irradiation of argon gas containing di-octyl phthalate (DOP) aerosols by 65 MeV quasi-monoenergetic neutrons were measured to study the formation mechanism of radioactive aerosols in high-energy radiation fields. Both the number size distribution and the activity-weighted size distribution were measured using an electrical low-pressure impactor. It was found that the 35Cl and 39Cl aerosols are formed by attachment of the radioactive atoms generated by the neutron-induced reaction to the DOP aerosol particles.

Aerosols↗
PubMed2001

Capillary gas chromatographic behaviour of tert.-hydroxylated steroids by trialkylsilylation.

Capillary gas chromatographic behaviour was studied for a variety of structurally different bile acids and sterols having one to two tert.-hydroxy groups, together with several sec.-hydroxy groups, at positions C-3, -5, -7, -12, -14, -17, -20, -24, and/or -25. The tert.-hydroxylated steroids were subjected to trimethylsilylation with hexamethyldisilazane/trimethylchlorosilane /pyridine and N,O-bis(trimethylsilyl)acetamide/N-trimethylsilylimidazole/trimethylchlorosilane, and dimethylethylsilylation with N,N,-dimethylethylsilylimidazole. The methylene unit values of the resulting trialkylsilylation products were used for determining their structures of partially and/or fully derivatised ethers. The reactivity of the trialkylsilylation of tert.-hydroxy groups was found to be significantly dependent not only on the derivatisation reagents and conditions used, but also on the position and steric factor of the tert.-hydroxy groups. The following general order of the decreasing reactivity of tert.-hydroxy groups in steroids by trialkylsilyl etherification was observed: 25>20, 24>5beta>17alpha>>14alpha.

Chromatography, Gas↗
PubMed2001

Apoptosis induced by in vitro infection with simian-human immunodeficiency chimeric virus in macaque and human peripheral blood mononuclear cells.

We investigated apoptosis induced by in vitro infection with the chimeric virus of simian immunodeficiency virus and human immunodeficiency virus (SHIV). Macaque and human peripheral blood mononuclear cells (PBMCs) were infected with pathogenic SHIV-89.6p (89.6p) or nonpathogenic SHIV-NM-3rN (NM-3rN). In macaque PBMCs, the extent of virus production and apoptosis induction in CD4(+) cells was much greater in 89.6p infection than in NM-3rN infection. The result was consistent with our previous study of in vivo SHIV infection. In human PBMCs, 89.6p replicated and induced apoptosis more extensively than did NM-3rN, when the cells were infected with the same infectious doses of the viruses. However, in cells infected with a high dose of NM-3rN, the levels of virus production and apoptosis induction were comparable to those in 89.6p infection. There was no significant difference in the extent of apoptosis induction between 89.6p and NM-3rN infection when growth curves of the two viruses matched. Thus, apoptosis induction by SHIV might depend quantitatively on the amount of virus production rather than on the strains of the virus. Moreover, the correlation between the extent of apoptosis induction and virus pathogenicity in macaque PBMCs has also been found in SHIV-infected macaques. This suggests that the profiles of SHIV infection in vitro reflect the in vivo phenomena. Therefore, the in vitro evaluation of apoptosis induction by SHIV could be useful as a safety test for the development of live-attenuated vaccines.

Animals↗
PubMed2001

Synthesis of a muscarinic receptor antagonist via a diastereoselective Michael reaction, selective deoxyfluorination and aromatic metal-halogen exchange reaction.

An efficient synthesis of a structurally unique, novel M(3) antagonist 1 is described. Compound 1 is conveniently disconnected retrosynthetically at the amide bond to reveal the acid portion 2 and the amine fragment 3. The synthesis of key intermediate 2 is highlighted by a ZnCl(2)-MAEP complex 19 catalyzed diastereoselective Michael reaction of dioxolane 7 with 2-cyclopenten-1-one (5) to establish the contiguous quaternary-tertiary chiral centers and a subsequent geminal difluorination of ketone 17 using Deoxofluor in the presence of catalytic BF(3).OEt(2). The synthesis of the amine moiety 3 is highlighted by the discovery of a novel n-Bu(3)MgLi magnesium-halogen exchange reaction for selective functionalization of 2,6-dibromopyridine. This new and practical metalation protocol obviated cryogenic conditions and upon quenching with DMF gave 6-bromo-2-formylpyridine (26) in excellent yield. Further transformations afforded the amine fragment 3 via reductive amination with 35, Pd-catalyzed aromatic amination, and deprotection. Finally, the highly convergent synthesis of 1 was accomplished by coupling of the two fragments. This synthesis has been used to prepare multi-kilogram quantities of the bulk drug.

Amides↗
PubMed2001

Expression of hMTH1 in the hippocampi of control and Alzheimer's disease.

The oxidized purine nucleoside triphosphatase, hMTH1, has a critical role towards preventing errors caused by oxidized purine nucleoside triphosphates such as 8-oxo-dGTP and 2-hydroxy-dATP. We investigated the immunohistochemical expression of hMTH1 in human hippocampal postmortem tissues representing non-neurological disease and Alzheimer's disease (AD). In the non-neurological subjects the hMTH1 protein was enriched in the stratum lucidum at CA3 corresponding to mossy fiber synapses. In AD subjects, the synaptic immunoreactivities at CA3 were significantly decreased, whereas they tended to be increased at the entorhinal cortex. We suggest that the expression of hMTH1 indicates indirect evidence of oxidative stress and its regulation is regionally differentiated in AD.

Aged↗
PubMed2001

A large outbreak of foodborne infection attributed to Providencia alcalifaciens.

The enteropathogenicity of Providencia alcalifaciens, a member of the family Enterobacteriaceae, has not yet been well established. In November 1996, a large outbreak of foodborne infection occurred in Fukui, Japan. In this study, the etiology of the outbreak was investigated. No other recognized enteropathogens were detected in patient fecal samples, but P. alcalifaciens was detected in 7 of 18 samples. The isolates were found to be clonal by pulsed-field gel electrophoresis. The patients who presented with gastroenteritis had elevated levels of specific antibody against the isolated P. alcalifaciens. The isolates showed invasion of Caco-2 cells and fluid accumulation in rabbit ileal loops. This study strongly suggests that the outbreak was caused by P. alcalifaciens. This is the first report of a large outbreak of foodborne infection attributed to the organism and provides definitive evidence that P. alcalifaciens is a causative agent of gastroenteritis.

Animals↗
PubMed2001

FK506-binding protein of the hyperthermophilic archaeum, Thermococcus sp. KS-1, a cold-shock-inducible peptidyl-prolyl cis-trans isomerase with activities to trap and refold denatured proteins.

The FK506 (tacrolimus)-binding protein (FKBP) type peptidyl-prolyl cis-trans isomerase (PPIase) in the hyperthermophilic archaeum Thermococcus sp. KS-1 was shown to be induced by temperature downshift to growth temperatures lower than the optimum. This PPIase (TcFKBP18) showed chaperone-like protein refolding activity in addition to PPIase activity in vitro. It refolded unfolded citrate synthase (CS) and increased the yield of the refolded protein. At a molar ratio of 15:1 ([TcFKBP18] to [CS]) in the refolding mixture, the recovered yield of folded CS was maximal at 62%, whereas that of spontaneous refolding was 11%. Increasing FKBP above a 15:1 ratio decreased the final yield, whereas the aggregation of unfolded CS was suppressed. A cross-linking analysis showed the formation of a complex between TcFKBP18 and unfolded CS (1:1 complex) at molar ratios of 3:1 to 15:1. However, molar ratios of 15:1 or 60:1 induced the binding of multiple FKBP molecules to an unfolded CS molecule (multimeric complex). Disrupting hydrophobic interaction by adding ethylene glycol at a molar ratio of 60:1 ([TcFKBP18] to [CS]) suppressed the formation of this multimeric complex, simultaneously enhancing CS refolding. FK506 also suppressed the formation of the multimeric complex while increasing the chaperone-like activity. These results suggest that the hydrophobic region of TcFKBP18, probably the FK506-binding pocket, was important for the interaction with unfolded proteins. No cross-linked product was detected between TcFKBP18 and native dimeric CS. TcFKBP18 probably traps the unfolded protein, then refolds and releases it in a native form. This FKBP might be important at growth temperatures lower than the optimum in Thermococcus sp. KS-1 cells.

Citrate (si)-Synthase↗
PubMed2001

Cytokine-independent Jak3 activation upon T cell receptor (TCR) stimulation through direct association of Jak3 and the TCR complex.

Jak3 is responsible for growth signals by various cytokines such as interleukin (IL)-2, IL-4, and IL-7 through association with the common gamma chain (gammac) in lymphocytes. We found that T cells from Jak3-deficient mice exhibit impairment of not only cytokine signaling but also early activation signals and that Jak3 is phosphorylated upon T cell receptor (TCR) stimulation. TCR-mediated phosphorylation of Jak3 is independent of IL-2 receptor/gammac but is dependent on Lck and ZAP-70. Jak3 was found to be assembled with the TCR complex, particularly through direct association with CD3zeta via its JH4 region, which is a different region from that for gammac association. These results suggest that Jak3 plays a role not only in cell growth but also in T cell activation and represents cross-talk of a signaling molecule between TCR and growth signals.

Animals↗
PubMed2001

Isolation and characterization of acetoacetyl-CoA thiolase gene essential for n-decane assimilation in yeast Yarrowia lipolytica.

Yarrowia lipolytica is a yeast which can utilize n-alkane as a sole carbon source. We isolated a Y. lipolytica peroxisomal acetoacetyl-CoA thiolase gene, PAT1, by complementation of a mutant that cannot utilize n-decane as a sole carbon source. We found that the putative PAT1 product had conserved features of peroxisomal acetoacetyl-CoA thiolase. We showed that the PAT1 disruptant was not able to grow on n-decane, and that n-decane-inducible acetoacetyl-CoA thiolase activity largely depended on PAT1. The original mutant carried a mutation involving the replacement of Gly382 with Glu. This mutation inactivated the ability of PAT1 to complement the defective n-decane utilization of the disruptant. These results indicate that PAT1 encodes peroxisomal acetoacetyl-CoA thiolase and is essential for n-decane utilization in Y. lipolytica.

Acetyl-CoA C-Acetyltransferase↗
PubMed2001

Monodansylcadaverine inhibits cytotoxicity of Vibrio parahaemolyticus thermostable direct hemolysin on cultured rat embryonic fibroblast cells.

The mechanism of action of Vibrio parahaemolyticus thermostable direct hemolysin (TDH) on cultured cells still remains unclear. We show that addition of osmotic stabilizers, such as polyethylene glycol and dextran, could not protect cultured rat embryonic fibroblast cells (Rat-1) against cytotoxicity induced by TDH, unlike their protection against the hemolytic activity of TDH. By contrast, 100 microM monodansylcadaverine, as well as the presence of 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) in medium, protected the cells against cytotoxicity of TDH. Binding of TDH to Rat-1 cells and intracellular localization of TDH were affected by monodansylcadaverine and EGTA as analyzed by flow cytometry and confocal microscopy. On the hemolytic activity of TDH, monodansylcadaverine and EGTA had no effect. These results suggest that the mechanism of cytotoxicity of TDH on Rat-1 cells was different from that of hemolytic activity of TDH on red blood cells.

Animals↗
PubMed2001

Complete genome sequence of enterohemorrhagic Escherichia coli O157:H7 and genomic comparison with a laboratory strain K-12.

Escherichia coli O157:H7 is a major food-borne infectious pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Here we report the complete chromosome sequence of an O157:H7 strain isolated from the Sakai outbreak, and the results of genomic comparison with a benign laboratory strain, K-12 MG1655. The chromosome is 5.5 Mb in size, 859 Kb larger than that of K-12. We identified a 4.1-Mb sequence highly conserved between the two strains, which may represent the fundamental backbone of the E. coli chromosome. The remaining 1.4-Mb sequence comprises of O157:H7-specific sequences, most of which are horizontally transferred foreign DNAs. The predominant roles of bacteriophages in the emergence of O157:H7 is evident by the presence of 24 prophages and prophage-like elements that occupy more than half of the O157:H7-specific sequences. The O157:H7 chromosome encodes 1632 proteins and 20 tRNAs that are not present in K-12. Among these, at least 131 proteins are assumed to have virulence-related functions. Genome-wide codon usage analysis suggested that the O157:H7-specific tRNAs are involved in the efficient expression of the strain-specific genes. A complete set of the genes specific to O157:H7 presented here sheds new insight into the pathogenicity and the physiology of O157:H7, and will open a way to fully understand the molecular mechanisms underlying the O157:H7 infection.

Bacterial Proteins↗
PubMed2001

Vibrio parahaemolyticus thermostable direct hemolysin can induce an apoptotic cell death in Rat-1 cells from inside and outside of the cells.

Rat-1 cells exposed to Vibrio parahaemolyticus thermostable direct hemolysin (TDH) developed morphological changes including shrinkage of the cells and reduction in the size of nuclei. Cells either microinjected with TDH or transfected with the tdh gene also showed morphological changes similar to those induced by externally added toxin. Furthermore, TDH-exposed or tdh-transfected cells both showed chromatin condensation and DNA fragmentation which suggest cells undergoing apoptosis. In contrast, expression of a TDH mutant (R7) did not reveal any cytotoxic effects. We demonstrate that expressed TDH was distributed in the cytoplasm. The interleukin-1beta-converting enzyme-related protease inhibitor ZVAD-FMK did not inhibit TDH cytotoxicity. Our results suggest that TDH can induce its cytotoxicity both from outside and from inside the cells and killed the cells through apoptosis.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Amino acid sequence and D/L-configuration determination methods for D-amino acid-containing peptides in living organisms.

D-amino acid-containing peptides with biological activities have been isolated from invertebrates and amphibians, and partial racemization of amino acid residues in mammalian peptides associated with aging and diseases have been discussed. Here, we review the amino acid configuration determination methods in these peptides and recent progress of simultaneous determination method for sequence and configuration of amino acid residues. The applicability of C-terminus sequence analysis and mass spectrometry to configuration determination of amino acids is also discussed.

Amino Acid Sequence↗
PubMed2001

Influence of tilapia mast cell lysate on vascular permeability.

Kinetics of vascular permeability was determined by measuring the amount of Evans blue leaked into the tilapia mast cell (tMC)-lysate injection site. Injection with tMC lysate enhanced the vascular permeability. The response consisted of three distinct phases, the first started immediately after the injection, the second started at about 2 h, reaching its maximum at 4 h, and the third response started at 12 h and continued for more than 24 h. Heating of the tMC lysate at 100 degrees C for 10 min had no effect on the first response, while the second response was significantly reduced by heating at 50 degrees C for 10 min. The tMCs seem to have two kinds of factors that enhance vascular permeability. The tMC lysate induced Ca2+ uptake by cultured tilapia endothelial cells, indicating that tMC products directly activate the endothelial cells and increase vascular permeability similar to products of mammalian mast cells. These results indicate that with respect to influence on vascular permeability tilapia mast cells resemble the mast cells of mammals.

Animals↗
PubMed2001

Portal vein thrombosis successfully treated with a colectomy in active ulcerative colitis: report of a case.

Portal vein thrombosis is a rare complication in ulcerative colitis. We present a patient with portal vein thrombosis in ulcerative colitis who was successfully treated with colectomy. A 38-year-old Japanese female was admitted to our hospital because of an exacerbation of colitis. Abdominal ultrasonography performed because of liver dysfunction showed the thrombus in an umbilical portion of the portal vein. The patient underwent a subtotal colectomy and ileostomy because her colitis did not respond to intensive intravenous therapy. Although portal vein thrombus was treated with an intravenous infusion of urokinase before the operation, no change in the thrombus size was found. Approximately three months after the colectomy, the thrombus of the portal vein disappeared without anticoagulant therapy. Although a resection of an inflamed colon may be theoretically effective in the thrombosis in the inflammatory bowel disease, its benefit has not been confirmed. Our case suggests that the resection of the diseased bowel may have a favorable effect on the course of portal vein thrombosis in acute attacks of ulcerative colitis.

Adult↗