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1.
Studies on the mechanism of intrinsic resistance to beta-lactam antibiotics in group D streptococci 总被引:14,自引:0,他引:14
R Williamson S B Calderwood R C Moellering A Tomasz 《Journal of general microbiology》1983,129(3):813-822
Six penicillin-binding proteins (PBPs) were detected in clinical isolates of each one of three group D streptococci: Streptococcus bovis, S. faecalis and S. faecium. When examined in whole organisms, the PBPs of S. faecium, the most penicillin-resistant species of group D streptococci, generally had lower affinities for the antibiotic than those of S. faecalis (intermediate penicillin resistance), which in turn were of lower affinity than those of S. bovis (penicillin-sensitive). On the other hand, no quantitative correlation could be established between the binding of penicillin to any one PBP or group of PBPs, and the penicillin MIC value for the corresponding micro-organism. Examination of the amounts of antibiotic bound and the rates of binding to PBPs of equal numbers of protoplasts and whole bacteria of S. faecalis and S. faecium, indicated that there was no permeability barrier to benzylpenicillin in the cell walls of these species. The lower antibacterial effectiveness of cephalothin compared with ampicillin in group D streptococci was paralleled by the higher concentrations of cephalothin needed in competition assays to inhibit the lower molecular size PBPs of these bacteria. 相似文献
2.
Susan DJ Chapple Anna M Crofts S Paul Shadbolt John McCafferty Michael R Dyson 《BMC biotechnology》2006,6(1):49-15
Background
A variety of approaches to understanding protein structure and function require production of recombinant protein. Mammalian based expression systems have advantages over bacterial systems for certain classes of protein but can be slower and more laborious. Thus the availability of a simple system for production and rapid screening of constructs or conditions for mammalian expression would be of great benefit. To this end we have coupled an efficient recombinant protein production system based on transient transfection in HEK-293 EBNA1 (HEK-293E) suspension cells with a dot blot method allowing pre-screening of proteins expressed in cells in a high throughput manner. 相似文献3.
Richard GH Immink Isabella AN Tonaco Stefan de Folter Anna Shchennikova Aalt DJ van Dijk Jacqueline Busscher-Lange Jan W Borst Gerco C Angenent 《Genome biology》2009,10(2):R24-16
Background
Plant MADS box proteins play important roles in a plethora of developmental processes. In order to regulate specific sets of target genes, MADS box proteins dimerize and are thought to assemble into multimeric complexes. In this study a large-scale yeast three-hybrid screen is utilized to provide insight into the higher-order complex formation capacity of the Arabidopsis MADS box family. SEPALLATA3 (SEP3) has been shown to mediate complex formation and, therefore, special attention is paid to this factor in this study. 相似文献4.
Christopher M. Harris Anna M. Ericsson Maria A. Argiriadi Claude Barberis David W. Borhani Andrew Burchat David J. Calderwood George A. Cunha Richard W. Dixon Kristine E. Frank Eric F. Johnson Joanne Kamens Silvia Kwak Biqin Li Kelly D. Mullen Denise C. Perron Lu Wang Neil Wishart Xiaoyun Wu Xiaolei Zhang Robert V. Talanian 《Bioorganic & medicinal chemistry letters》2010,20(1):334-337
We describe structure-based optimization of a series of novel 2,4-diaminopyrimidine MK2 inhibitors. Co-crystal structures (see accompanying Letter) demonstrated a unique inhibitor binding mode. Resulting inhibitors had IC50 values as low as 19 nM and moderate selectivity against a kinase panel. Compounds 15, 31a, and 31b inhibit TNFα production in peripheral human monocytes. 相似文献
5.
6.
Maria A. Argiriadi Anna M. Ericsson Christopher M. Harris David L. Banach David W. Borhani David J. Calderwood Megan D. Demers Jennifer DiMauro Richard W. Dixon Jennifer Hardman Silvia Kwak Biqin Li John A. Mankovich Douglas Marcotte Kelly D. Mullen Baofu Ni M. Pietras Ramkrishna Sadhukhan Silvino Sousa Medha J. Tomlinson Robert V. Talanian 《Bioorganic & medicinal chemistry letters》2010,20(1):330-333
MK2 is a Ser/Thr kinase of significant interest as an anti-inflammatory drug discovery target. Here we describe the development of in vitro tools for the identification and characterization of MK2 inhibitors, including validation of inhibitor interactions with the crystallography construct and determination of the unique binding mode of 2,4-diaminopyrimidine inhibitors in the MK2 active site. Use of these tools in the optimization of a potent and selective inhibitor lead series is described in the accompanying Letter. 相似文献
7.
Study design
A prospective treatment study with a new brace was conducted Objective. To evaluate radiological and subjective clinical results after one year conservative brace treatment with pressure onto lordosis at the thoracolumbar joint in children with scoliosis and kyphosis.Summary of background data
Conservative brace treatment of adolescent scoliosis is not proven to be effective in terms of lasting correction. Conservative treatment in kyphotic deformities may lead to satisfactory correction. None of the brace or casting techniques is based on sagittal forces only applied at the thoracolumbar spine (TLI= thoracolumbar lordotic intervention). Previously we showed in patients with scoliosis after forced lordosis at the thoracolumbar spine a radiological instantaneous reduction in both coronal curves of double major scoliosis.Methods
A consecutive series of 91 children with adolescent scoliosis and kyphosis were treated with a modified symmetric 30 degrees Boston brace to ensure only forced lordosis at the thoracolumbar spine. Scoliosis was defined with a Cobb angle of at least one of the curves [greater than or equal to] 25 degrees and kyphosis with or without a curve <25 degrees in the coronal plane. Standing radiographs were made i) at start, ii) in brace at beginning and iii) after one year treatment without brace.Results
Before treatment start ??in brace?? radiographs showed a strong reduction of the Cobb angles in different curves in kyphosis and scoliosis groups (sagittal n = 5 all p < 0.001, pelvic obliquity p < 0.001). After one year of brace treatment in scoliosis and kyphosis group the measurements on radiographs made without brace revealed an improvement in 3 Cobb angles each.Conclusion
Conservative treatment using thoracolumbar lordotic intervention in scoliotic and kyphotic deformities in adolescence demonstrates a marked improvement after one year also in clinical and postural criteria. An effect not obtained with current brace techniques. 相似文献8.
Analysis of gene expression in a human cell line stably transduced with herpesvirus saimiri 下载免费PDF全文
Hall KT Giles MS Goodwin DJ Calderwood MA Carr IM Stevenson AJ Markham AF Whitehouse A 《Journal of virology》2000,74(16):7331-7337
Herpesvirus saimiri (HVS) is the prototype gamma-2 herpesvirus; it has significant homology to the human gammaherpesviruses Kaposi's sarcoma-associated virus and Epstein-Barr virus and the murine gammaherpesvirus murine herpesvirus 68. HVS causes a persistent asymptomatic infection in its natural host, the squirrel monkey. Both subgroups A and C possess the ability to immortalize common marmoset T lymphocytes to interleukin-2-independent proliferation. However, only subgroup C is capable of transforming human, rabbit, and rhesus monkey lymphocytes in vitro. In addition, HVS can stably transduce a variety of human cell lines where the virus persists as a nonintegrating circular episome. In this study, we have developed a system in which the HVS DNA is stably maintained as a nonintegrated circular episome in the human lung carcinoma cell line A549. Virus production can be reactivated using chemical inducing agents, including tetradecanoyl phorbol acetate and n-butyrate, suggesting that the infection in human A549 cells is latent. To analyze virus gene expression in these stably transduced cells, Northern blot analysis was performed using a series of probes produced from restriction fragments spanning the entire coding region of the HVS genome. This demonstrated that an adjacent set of genes containing open reading frames (ORFs) 71 to 73 are expressed in this stably transduced cell line. Moreover, these genes are transcribed as a polycistronic mRNA species produced from a common promoter upstream of ORF 73. This model may serve as a useful tool in the further analysis of the role of ORFs 71 to 73 in gamma-2 herpesvirus latency. 相似文献
9.
The ITS sequences of Acropora spp. are the shortest so far identified in
any metazoan and are among the shortest seen in eukaryotes; ITS1 was 70-80
bases, and ITS2 was 100-112 bases. The ITS sequences were also highly
variable, but base composition and secondary structure prediction indicate
that divergent sequence variants are unlikely to be pseudogenes. The
pattern of variation was unusual in several other respects: (1) two
distinct ITS2 types were detected in both A. hyacinthus and A. cytherea,
species known to hybridize in vitro with high success rates, and a putative
intermediate ITS2 form was also detected in A. cytherea; (2) A. valida was
found to contain highly (29%) diverged ITS1 variants; and (3) A.
longicyathus contained two distinct 5.8S rDNA types. These data are
consistent with a reticulate evolutionary history for the genus Acropora.
相似文献
10.