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991.
The function of SmpB protein in the trans-translation system was evaluated using the well-defined cell-free translation system consisting of purified ribosome, alanyl-tRNA synthetase and elongation factors. The analysis showed that SmpB protein enhances alanine-accepting activity of tmRNA and that SmpB protein and tmRNA are sufficient to complete the trans-translation process in the presence of translational components. Moreover, SmpB is indispensable in the addition of tag-peptide onto ribosomes by tmRNA. In particular, the A-site binding of tmRNA is inhibited in the absence of SmpB. 相似文献
992.
Minamiyama Y Takemura S Nishino Y Okada S 《Redox report : communications in free radical research》2002,7(5):339-342
The mechanism of nitrate tolerance is poorly defined. We studied the rat P450 (CYP)-catalyzed conversion of organic nitrate to nitric oxide (NO) by purified CYP isoforms and the relationship between P450 expression and nitrate tolerance following continuous infusion of organic nitrates in rats. CYP1A2 effectively formed NO from isosorbide dinitrate and nitroglycerine (NTG). The hypotensive effect of an NTG bolus injection was abolished in rats which had been previously given a continuous 48 h infusion of NTG. Nitrate tolerance was reversible to control levels 2 days after cessation of the continuous infusion. At 48 h after infusion, NTG-induced NO generation of the vessels increased in acetone (a P450 inducer)-pretreated rats, and nitrite and nitrate levels were markedly greater than in normal rats. The appearance and disappearance of P450 isoforms paralleled the conversion of organic nitrates to NO as assessed by immunohistochemistry and Western blotting. Our observations indicate that nitrate tolerance is in large part the result of decreased P450 expression and activity. Interventions that maintain or increase P450 activity may be a useful strategy to provide sustained relief from ischemic conditions in humans. 相似文献
993.
The relation between the energies of ion movement and ATP hydrolysis is unknown in tissues with widely varying electric potentials. Consequently, we measured the concentration of the nine major inorganic ions in the extra- and intracellular phases in heart, liver, and red cells with resting electrical potentials, E(N), of -86, -28, and -6 mV, respectively, under six different physiological conditions. We calculated the Nernst electric potential and the energy of ion movement between the phases. We found that the energy of ATP hydrolysis was essentially constant, between -54 and -58 kJ/mol, in all tissues and conditions. In contrast, as E(N) decreased, the energies of the Na+ and K+ gradients decreased, with slopes approximating their valence. The difference between the energies of Na+ and K+ gradients remained constant at 17 kJ/mol, which is approximately one third of the energy of ATP hydrolysis, demonstrating near-equilibrium of the Na+/K+ ATPase in all tissues under all conditions. All cations, except K+, were pumped out of cells and all anions, except Cl- in liver and red cell, were pumped into cells. We conclude that the energy of ATP was expressed in Na+/K+ ATPase and its linked inorganic ion transporters to create a Gibbs-Donnan near-equilibrium system, an inherent part of which was the electric potential. 相似文献
994.
Kawai Y Ishizuka T Kajita K Miura A Ishizawa M Natsume Y Uno Y Morita H Yasuda K 《IUBMB life》2002,54(6):365-370
Pretreatment with glucocorticoids for 60 min depressed insulin-stimulated uptake of 2-[3H] deoxyglucose (2-DOG), an effect that neither cycloheximide, an inhibitor of protein synthesis, nor RU38486, a glucocorticoid receptor antagonist, could restore. Preincubation with conventional PKC inhibitors restored dexamethasone-induced insulin resistance. We also examined the dexamethasone-mediated inhibitory effect on insulin-induced 2-DOG uptake in adipocytes overexpressed with wild-type and dominant negative forms of PKCbeta. The dexamethasone-mediated inhibitory effect on insulin-induced 2-DOG uptake was abrogated in adipocytes overexpressed with dominant-negative PKCbeta. These results indicate that PKCbeta may play an important role in glucocorticoid-induced insulin resistance. 相似文献
995.
Uzawa H Kamiya S Minoura N Dohi H Nishida Y Taguchi K Yokoyama S Mori H Shimizu T Kobayashi K 《Biomacromolecules》2002,3(3):411-414
A simple globobiosyl (Gb2) ceramide mimic carrying a monoalkyl chain (C18) was applied for a monolayer Langmuir-Blodgett (L-B) technique to detect Shiga toxins (Stxs) by a quartz crystal microbalance (QCM) method. The artificial glycolipid, synthesized from penta-O-acetyl-D-galactopyranose via a conventional glycosidation pathway, was developed at the air-water surface for the formation of the monolayer film. Then, the film was transferred onto a QCM cell surface modified with alkanethiols. Upon the addition of each of Stx-1 and Stx-2, the decrease of frequency reached saturation within 45 min at a few nanogram order per quartz cell. Binding constants (Ka) estimated for each of Stx-1 and Stx-2 showed little difference between the two toxins. On the other hand, in the presence of an artificial acrylamido Gb2 copolymer as a competitive inhibitor, the two toxins showed a large difference in the binding behavior to the L-B monolayer. 相似文献
996.
A missense Glu298Asp variant in the endothelial nitric oxide synthase gene is associated with coronary spasm in the Japanese 总被引:42,自引:0,他引:42
Michihiro Yoshimura H. Yasue Masafumi Nakayama Yukio Shimasaki Hitoshi Sumida Seigo Sugiyama Kiyotaka Kugiyama Hisao Ogawa Yoshihiro Ogawa Yoshihiko Saito Yoshihiro Miyamoto Kazuwa Nakao 《Human genetics》1998,103(1):65-69
Coronary spasm plays an important role in the pathogenesis of not only variant angina but also ischemic heart disease in
general. However, the precise mechanism(s) by which coronary spasm occurs remains to be elucidated. Coronary spasm may arise
from interactions between environmental and genetic factors. Endothelial derived nitric oxide (NO) has been implicated in
the control of vascular tone. We have recently shown that both basal and acetylcholine (ACh)-induced NO activities are impaired
in the coronary arteries of patients with coronary spasm. The purpose of this study has been to elucidate the possible variants
that occur in the coding region of the endothelial nitric oxide synthase (eNOS) gene and that may be associated with coronary
spasm. After initial screening in the entire 26 coding regions of the eNOS gene, we found a missense Glu298Asp variant in
exon 7 in patients with coronary spasm. We subsequently performed a larger scale study involving 113 patients with coronary
spasm and 100 control subjects, who were all diagnosed by intracoronary injection of ACh. The analysis revealed a significant
difference in the distribution of the variant between the coronary spasm group (21.2%) and control group (9.0%; P=0.014 for dominant effect). Thus, we have found the missense Glu298Asp variant in the eNOS gene by the analysis of its entire
26 coding regions. The variant is significantly associated with coronary spasm.
Received: 2 February 1998 / Accepted: 9 April 1998 相似文献
997.
Production of Uninfectious Human Immunodeficiency Virus Type 1 Containing Viral Protein R Fused to a Single-Chain Antibody against Viral Integrase
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A single-chain antibody (scAb) against human immunodeficiency virus type 1 (HIV-1) integrase was expressed as a fusion protein of scAb and HIV-1 viral protein R (Vpr), together with the HIV-1 genome, in human 293T cells. The expression did not affect virion production much but markedly reduced the infectivity of progeny virions. The fusion protein was found to be incorporated into the virions. The incorporation appears to account for the reduced infectivity. 相似文献
998.
Vaccination with a Recombinant Vesicular Stomatitis Virus Expressing an Influenza Virus Hemagglutinin Provides Complete Protection from Influenza Virus Challenge 总被引:20,自引:12,他引:8
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Anjeanette Roberts Evelyne Kretzschmar Archibald S. Perkins John Forman Ryan Price Linda Buonocore Yoshihiro Kawaoka John K. Rose 《Journal of virology》1998,72(6):4704-4711
Since the development of a system for generating vesicular stomatitis virus (VSV) from plasmid DNAs, our laboratory has reported the expression of several different glycoproteins from recombinant VSVs. In one of these studies, high-level expression of an influenza virus hemagglutinin (HA) from a recombinant VSV-HA and efficient incorporation of the HA protein into the virions was reported (E. Kretzschmar, L. Buonocore, M. J. Schnell, and J. K. Rose, J. Virol. 71:5982–5989, 1997). We report here that VSV-HA is an effective intranasal vaccine vector that raises high levels of neutralizing antibody to influenza virus and completely protects mice from bronchial pneumonia caused by challenge with a lethal dose of influenza A virus. Additionally, these recombinant VSVs are less pathogenic than wild-type VSV (serotype Indiana). This vector-associated pathogenicity was subsequently eliminated through introduction of specific attenuating deletions. These live attenuated recombinant VSVs have great potential as vaccine vectors. 相似文献
999.
Isao Nagano Miyuki Kunishima Yoshihiro Itoh Zhiliang Wu Yuzo Takahashi 《Microbiology and immunology》1998,42(5):371-376
We constructed primers for multiplex polymerase chain reaction (PCR) to detect verotoxin-producing Escherichia coli (VTEC) O157:H7. The multiplex PCR primers were designed from the sequence of the flagellin structural gene of Escherichia coli flagellar type H7 (GenBank under accession number L07388), and from the sequence of the rfbE gene of Escherichia coli O157:H7 (GenBank under accession number S83460). In addition to these primers, we used a primer pair reported by Karch and Meyer (J. Clin, Microbiol. 27: 2751-2757, 1989) to amplify various VT genes from VTEC. All of the examined specimens (18 isolates) of VT-producing E. coli O157:H7 showed a positive result by the multiplex PCR test with the three sets of primers. The sensitivity of detection for VT-producing E. coli O157:H7 was shown to be at least 3,000 cells per PCR tube. 相似文献
1000.
Narusaka Yoshihiro; Narusaka Mari; Kobayashi Hirokazu; Satoh Kimiyuki 《Plant & cell physiology》1998,39(6):620-626
Random mutations were introduced into the DNA fragment of thepsbA2 gene of Synechocystis sp. PCC 6803, which encodes thecarboxyl-terminal 178 amino acid region of the Dl protein ofthe PSII reaction center, by in vitro random mutagenesis toobtain Dl species resistant to herbicides and to understandthe protein-herbicide interactions. The mutants were screenedon the criterion of resistance to either 1 µM DCMU or10 µM atrazine. In these mutants, amino acid substitutionswere distributed throughout the entire area of the targetedregion in the Dl protein. However, in every mutant, except forone case, the substitution was present in the region describedas the "herbicide-binding niche", i.e., between Phe211 and Leu275,although some amino acid substitutions which were not previouslydescribed were found at residues known to be involved with herbicideaffinity. Thus, the result of random mutagenesis basically supportsthe validity of the proposed structural model for the Dl protein,as well as of the herbicide-binding niche. Preliminary characterizationof the herbicide-resistant mutants obtained in this study hasalso been conducted. (Received December 8, 1997; ) 相似文献