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71.
Manuel J. Steinbauer Richard Field John‐Arvid Grytnes Panayiotis Trigas Claudine Ah‐Peng Fabio Attorre H. John B. Birks Paulo A. V. Borges Pedro Cardoso Chang‐Hung Chou Michele De Sanctis Miguel M. de Sequeira Maria C. Duarte Rui B. Elias José María Fernández‐Palacios Rosalina Gabriel Roy E. Gereau Rosemary G. Gillespie Josef Greimler David E. V. Harter Tsurng‐Juhn Huang Severin D. H. Irl Daniel Jeanmonod Anke Jentsch Alistair S. Jump Christoph Kueffer Sandra Nogué Rüdiger Otto Jonathan Price Maria M. Romeiras Dominique Strasberg Tod Stuessy Jens‐Christian Svenning Ole R. Vetaas Carl Beierkuhnlein 《Global Ecology and Biogeography》2016,25(9):1097-1107
72.
Jemy A Gutierrez Minkui Luo Vipender Singh Lei Li Rosemary L Brown Gillian E Norris Gary B Evans Richard H Furneaux Peter C Tyler Gavin F Painter Dirk H Lenz Vern L Schramm 《ACS chemical biology》2007,2(11):725-734
Transition states can be predicted from an enzyme's affinity to related transition-state analogues. 5'-Methylthioadenosine nucleosidases (MTANs) are involved in bacterial quorum sensing pathways and thus are targets for antibacterial drug design. The transition-state characteristics of six MTANs are compared by analyzing dissociation constants (K(d)) with a small array of representative transition-state analogues. These inhibitors mimic early or late dissociative transition states with K(d) values in the picomolar range. Our results indicate that the K(d) ratio for mimics of early and late transition states are useful in distinguishing between these states. By this criterion, the transition states of Neisseria meningitides and Helicobacter pylori MTANs are early dissociative, whereas Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, and Klebsiella pneumoniae MTANs have late dissociative characters. This conclusion is confirmed independently by the characteristic [1'- (3)H] and [1'- (14)C] kinetic isotope effects (KIEs) of these enzymes. Large [1'- (3)H] and unity [1'- (14)C] KIEs are observed for late dissociative transition states, whereas early dissociative states showed close-to-unity [1'- (3)H] and significant [1'- (14)C] KIEs. K d values of various MTANs for individual transition-state analogues provide tentative information about transition-state structures due to varying catalytic efficiencies of enzymes. Comparing K d ratios for mimics of early and late transition states removes limitations inherent to the enzyme and provides a better predictive tool in discriminating between possible transition-state structures. 相似文献
73.
Douglas E. Rawlings Rosemary A. Dorrington Jürg Rohrer Anne-Marie Clennel 《FEMS microbiology reviews》1993,11(1-3):3-7
Abstract: A 12.4-kb plasmid, pTF-FC2, that was isolated from Thiobacillus ferrooxidans and which is capable of replication in a wide range of Gram-negative bacteria, has been sequenced. The extent of the regions involved in both replication and mobilization have been delineated. The site of initiation of replication ( oriV ) has been localized on a 185-bp fragment and the origin of transfer ( oriT ) on a 138-bp fragment. Three proteins that were essential for replication and four that were essential for mobilization have been identified. The origin of replication was clearly similar to that of the IncQ plasmids although no complementation or incompatibility between pTF-FC2 and the IncQ plasmid, R300B, was detected. There was a clear similarity in the size,location and amino acid sequence of the proteins of the pTF-FC2 mobilization region with those of the TraI region of the IncP plasmids, RP4 and R751.Two inverted repeated sequences which had 37/38-bp and 38/38-bp sequence identity with the Tn 21 transposon were identified. The C-terminal part of a transposase and the N-terminal portion of a resolvase were located between the inverted repeats. These open reading frames are most likely the remnants of a defective transposon. A protein with homology to a mercury- resistance regulator was also present within the transposon-like element although no gene encoding for mercury reductase could be indentified. 相似文献
74.
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76.
Rezaie-Majd S Murar J Nelson DP Kelly RF Hong Z Lang IM Varghese A Weir EK 《American journal of physiology. Regulatory, integrative and comparative physiology》2004,287(5):R1209-R1213
Plasma levels of serotonin are elevated in primary pulmonary hypertension even after bilateral lung transplantation, suggesting a possible etiologic role. Serotonin is released primarily from the small intestine. Anorectic agents, such as dexfenfluramine, which can cause pulmonary hypertension, are known to inhibit potassium channels in vascular smooth muscle cells. We examined the hypothesis that dexfenfluramine may stimulate release of serotonin from the ileum by inhibition of K+ channels. In an isolated loop of rat ileum perfused with a physiological salt solution, the administration of dexfenfluramine, its major metabolite D-norfenfluramine, the potassium channel blocker 4-aminopyridine (5 mM), and caffeine (30 mM) increased serotonin levels in the venous effluent. Potassium chloride (60 mM) tended to increase serotonin levels. In genetically susceptible individuals, dexfenfluramine may induce pulmonary hypertension by increasing cytosolic calcium in enterochromaffin cells of the small intestine, thus releasing serotonin and causing vasoconstriction. This work indicates that dexfenfluramine and its major metabolite d-norfenfluramine can increase serotonin release from the small intestine. 相似文献
77.
Matrix metalloproteinase-2 and -9 secretion by the equine ovary during follicular growth and prior to ovulation 总被引:3,自引:0,他引:3
Riley SC Thomassen R Bae SE Leask R Pedersen HG Watson ED 《Animal reproduction science》2004,81(3-4):329-339
Profound hormonally controlled tissue remodelling occurs in the equine ovary for follicle growth and development, and also for the alteration in follicle shape directed towards the ovulation fossa, the site where ovulation occurs. The aim of this study was to examine the spatial and temporal regulation of matrix metalloproteinases (MMP)-2 and MMP-9, important enzymes in tissue remodelling, during follicle growth, and ovulation. Using gelatin substrate zymography, we measured these MMPs in follicular fluid of large anovulatory follicles collected during spring transition, early dominant follicles (> 23 mm), and at oestrus in follicles approximately 3 days prior to ovulation, and post-hCG treatment when ovulation was predicted in approximately 4 h. The most abundant activity detected in follicular fluid was MMP-2, although there were no changes in secretion or activation in association with ovulation. The activity of MMP-9 was detected in lower amounts, with no changes prior to ovulation, although it decreased significantly (P < 0.05) post-hCG treatment. At oestrus, when different regions of the ovary were maintained in explant culture for 24 h, there were no significant changes in either MMP-2 or MMP-9 secretion by stromal tissues collected at the ovarian fossa, adjacent to the preovulatory follicle but away from the fossa, and a further site remote from the preovulatory follicle. Over this same time period, follicular progesterone (P < 0.01) and oestradiol (P < 0.05) increased significantly, although oestradiol tended to decrease after hCG administration. These findings indicate that MMP-2 and MMP-9 are not key acute regulators for the changes in follicle shape immediately prior to ovulation. 相似文献
78.
Dyatkin AB Hoekstra WJ Kinney WA Kontoyianni M Santulli RJ Kimball ES Fisher MC Carolyn Fisher M Prouty SM Abraham WM de Garavilla L Andrade-Gordon P Hlasta DJ He W Hornby PJ Damiano BP Maryanoff BE 《Bioorganic & medicinal chemistry letters》2004,14(3):591-596
The design, synthesis, and biological activity of novel alpha(4)beta(1) and alpha(4)beta(7) integrin antagonists, containing a bridged azabicyclic nucleus, are reported. Conformational analysis of targets containing an azabicyclo[2.2.2]octane carboxylic acid and known integrin antagonists indicated that this azabicycle would be a suitable molecular scaffold. Variation of substituents on the pendant arylsulfonamide and phenylalanine groups resulted in potent alpha(4)beta(1)-selective and dual alpha(4)beta(1)/alpha(4)beta(7) antagonists. Potent compounds 11i, 11h, and 14 were effective in the antigen-sensitized sheep model of asthma. 相似文献
79.
Chen P Norris D Das J Spergel SH Wityak J Leith L Zhao R Chen BC Pitt S Pang S Shen DR Zhang R De Fex HF Doweyko AM McIntyre KW Shuster DJ Behnia K Schieven GL Barrish JC 《Bioorganic & medicinal chemistry letters》2004,14(24):6061-6066
A series of substituted 2-(aminoheteroaryl)-thiazole-5-carboxamide analogs have been synthesized as novel, potent inhibitors of the Src-family kinase p56Lck. Among them, compound 2 displayed superior in vitro potency and excellent in vivo efficacy. 相似文献
80.
Model of angiogenesis in mice with severe combined immunodeficiency (SCID) and xenoengrafted with Epstein-Barr virus-transformed B cells 总被引:1,自引:0,他引:1
Xenoengraftment of human cells in mice with severe combined immunodeficiency (SCID) has been used as a model system to study the mechanisms of B-cell lymphomagenesis. In the study reported here, we determined that SCID mice can also be used as a model to study angiogenesis in B-cell lymphomas. The C.B-17 scid/scid mice were xenotransplanted with Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL), and we determined whether CD31, a marker found on endothelial cells, was detected in the human B-cell lymphomas that developed in these mice. Microvessel formation was identified by use of immunohistochemical staining for CD31. To assess possible mechanisms of angiogenic stimulus, we analyzed the expression of interleukin 8 (IL-8), a chemokine documented to promote angiogenesis, in non-small-cell lung cancer and bronchogenic carcinomas. We observed that a panel of LCL and LCL-lymphomas expressed IL-8 mRNA and protein. Neutralization of IL-8, however, did not inhibit lymphomagenesis, suggesting that IL-8 is not essential for angiogenesis in this model. To examine other parameters of angiogenesis, we identified expression of vascular endothelial growth factor in the lymphomas. These data suggest that angiogenesis accompanies EBV-associated B-cell lymphoma development, but IL-8 is not essential for this process. Thus, the SCID mouse model is amenable to testing of anti-angiogenic factors. 相似文献