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排序方式: 共有210条查询结果,搜索用时 15 毫秒
51.
52.
The epidermolytic toxins are serine proteases 总被引:9,自引:0,他引:9
Certain strains of Staphylococcus aureus usually belonging to phage group II produce epidermolytic toxins (ETA and ETB) which cause intraepidermal splitting in mice, neonates and occasionally adults. Amino acid sequences of ETA and ETB have been reported but the mechanism of epidermolysis remains unknown. A search of the NBRF-PIR computer database showed the toxins to have significant sequence similarity with staphylococcal V8 protease and that the catalytic triad of V8 protease is present in ETA and ETB. Comparison of ETA, ETB and V8 protease with other members of the trypsin-like serine protease family revealed little homology save for the immediate vicinity of the residues constituting the catalytic triad. The toxins, therefore, exhibit a distant relationship to mammalian serine proteases. A potential Ca2(+)-binding loop was identified in ETA (but not ETB) on the basis of sequence similarity with the second calcium-binding loop of rat intestinal calcium-binding protein. Epidermolysis produced by ETA in the mouse bioassay was shown to be inhibited by the presence of EDTA consistent with a Ca2(+)-dependent mechanism. 相似文献
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Metastasis of a cancer to another coexisting tumor is a very rare event. A case of primary squamous cell carcinoma of the skin metastatic to lymph nodes replaced by chronic lymphoid leukemia and diagnosed by fine needle aspiration is presented. To our knowledge, this peculiar case represents the first time that these two concurrent tumors were diagnosed by fine needle aspiration. 相似文献
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Mariangela Urbano Miguel Guerrero Jian Zhao Subash Velaparthi S. Adrian Saldanha Peter Chase Zhiwei Wang Olivier Civelli Peter Hodder Marie-Therese Schaeffer Steven Brown Hugh Rosen Edward Roberts 《Bioorganic & medicinal chemistry letters》2012,22(23):7135-7141
Novel small molecule antagonists of NPBWR1 (GPR7) are herein reported. A high-throughput screening (HTS) of the Molecular Libraries-Small Molecule Repository library identified 5-chloro-4-(4-methoxyphenoxy)-2-(p-tolyl)pyridazin-3(2H)-one as a NPBWR1 hit antagonist with micromolar activity. Design, synthesis and structure–activity relationships study of the HTS-derived hit led to the identification of 5-chloro-2-(3,5-dimethylphenyl)-4-(4-methoxyphenoxy)pyridazin-3(2H)-one lead molecule with submicromolar antagonist activity at the target receptor and high selectivity against a panel of therapeutically relevant off-target proteins. This lead molecule may provide a pharmacological tool to clarify the molecular basis of the in vivo physiological function and therapeutic utility of NPBWR1 in diverse disease areas including inflammatory pain and eating disorders. 相似文献
56.
Cleber Witt Saldanha Caio Gomide Otoni Jéssica Laísca Fernanda de Azevedo Leonardo Lucas Carnevalli Dias Mailson Monteiro do Rêgo Wagner Campos Otoni 《Plant Cell, Tissue and Organ Culture》2012,110(3):413-422
In vitro propagated plants under conditions of low gas exchange generally show morphological and physiological anomalies that lead to high mortality rates during ex vitro acclimatization. The use of gas-permeable membranes increases natural ventilation in culture vessels, photosynthesis and growth rates. However, commercial membranes are expensive, which limits their application. In this study, low-cost, simple to manufacture, alternative membranes were developed to promote gas exchange in jars used for in vitro plant tissue culture. The membranes were developed using polytetrafluoroethylene film and two or three layers of microporous tape (Missner & Missner?), and were designed to increase the growth of nodal cultures of Pfaffia glomerata (Brazilian ginseng). Conditions that provided higher gas exchange led to an increase in plant growth and content of photosynthetic pigments compared to a closed system without a gas-permeable membrane. The alternative membranes showed similar results for water vapor loss rate and photosynthetic pigments when compared to a commercial membrane. The alternative membranes were also an efficient barrier against contamination and remained intact after being autoclaved multiple times. Among the membranes tested, the traits of the P. glomerata in vitro-derived plants were similar when propagated using the alternative membrane with three layers of microporous tape or the commercial membrane. However, the alternative membrane has a unit cost that is ten times lower than the commercial membrane. 相似文献
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Reduced-impact Logging has Little Effect on Temporal Activity of Frugivorous Bats (Chiroptera) in Lowland Amazonia 总被引:1,自引:0,他引:1
Steven J. Presley Michael R. Willig Luiz N. Saldanha Joseph M. Wunderle Jr . Ivan Castro-Arellano 《Biotropica》2009,41(3):369-378
Reduced-impact logging (RIL) represents a viable option for sustainable use of Neotropical lowland forests while minimizing negative effects on local biodiversity. Many Neotropical bats of the family Phyllostomidae provide ecosystem services associated with pollination and seed dispersal that promote the regeneration of disturbed areas; therefore, effects of RIL on these species is of particular concern. We determined patterns of temporal activity, degree of temporal overlap of activity, and dispersion in peaks of activity for seven abundant species of frugivorous bat in Tapajós National Forest, Pará, Brazil. In addition, we evaluated the effects of RIL at a harvest level of 18.7 m3 /ha and habitat physiognomy on temporal patterns of activity for these species. Bats were surveyed for four nights at each of 96 sites for a total sampling effort of 64,512 net-m-h. Sites were distributed among four experimental blocks, two blocks of unlogged forest and two blocks of forest subjected to RIL. Half of the sites in each management type were in forest gaps and half were in closed-canopy forest. In general, species exhibited similar patterns of activity, and greater than expected temporal overlap in activity among species. RIL and forest physiognomy had little effect on activity patterns of species. RIL in Amazonia removes fewer trees than do naturally occurring treefalls and such changes in habitat structure do not alter activity patterns of frugivorous bats. Evidence suggests that RIL does not have an appreciable adverse effect on frugivorous bats in Amazonia. 相似文献
59.
The extracellular regions of PSMA and the transferrin receptor contain an aminopeptidase domain: implications for drug design
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Mahadevan D Saldanha JW 《Protein science : a publication of the Protein Society》1999,8(11):2546-2549
The Aeromonas proteolytica aminopeptidase (AMP), Pseudomonas sp. (RS-16) carboxypeptidase G2 (CPG2), and Streptomyces griseus aminopeptidase (SGAP) are zinc dependent proteolytic enzymes with cocatalytic zinc ion centers and a conserved aminopeptidase fold. A BLAST search with the sequence of the solved AMP structure indicated that a similar domain could be found in prostate-specific membrane antigen (PSMA) and the transferrin receptor (TfR). When the PSMA or TfR sequence was input into the THREADER program, the top structural matches were SGAP and AMP confirming that these are structurally conserved domains. Optimal sequence alignment of PSMA and TfR using the known three-dimensional structures of AMP, CPG2, and SGAP shows that the critical amino acids involved in forming the catalytic pocket are conserved in PSMA but absent in the TfR. The specificity pocket in AMP is formed from four aromatic side chains and the equivalent region in CPG2/PSMA has a changed sequence pattern. Since CPG2 and PSMA are folate hydrolases, the changed specificity pocket leaves space to accommodate the large pteroate moiety of folic acid. In contrast, no enzyme function has been ascribed to the TfR. 相似文献
60.
Control mechanisms in the regulation of telomerase reverse transcriptase expression in differentiating human teratocarcinoma cells 总被引:2,自引:0,他引:2