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101.
102.
Jonathan M Carlson Arijit Chakravarty Radhika S Khetani Robert H Gross 《BMC bioinformatics》2006,7(1):254-17
Background
The identification of statistically overrepresented sequences in the upstream regions of coregulated genes should theoretically permit the identification of potential cis-regulatory elements. However, in practice many cis-regulatory elements are highly degenerate, precluding the use of an exhaustive word-counting strategy for their identification. While numerous methods exist for inferring base distributions using a position weight matrix, recent studies suggest that the independence assumptions inherent in the model, as well as the inability to reach a global optimum, limit this approach. 相似文献103.
Zakrzewski JL Kochman AA Lu SX Terwey TH Kim TD Hubbard VM Muriglan SJ Suh D Smith OM Grubin J Patel N Chow A Cabrera-Perez J Radhakrishnan R Diab A Perales MA Rizzuto G Menet E Pamer EG Heller G Zúñiga-Pflücker JC Alpdogan O van den Brink MR 《Nature medicine》2006,12(9):1039-1047
Immunoincompetence after allogeneic hematopoietic stem cell transplantation (HSCT) affects in particular the T-cell lineage and is associated with an increased risk for infections, graft failure and malignant relapse. To generate large numbers of T-cell precursors for adoptive therapy, we cultured mouse hematopoietic stem cells (HSCs) in vitro on OP9 mouse stromal cells expressing the Notch-1 ligand Delta-like-1 (OP9-DL1). We infused these cells, together with T-cell-depleted mouse bone marrow or purified HSCs, into lethally irradiated allogeneic recipients and determined their effect on T-cell reconstitution after transplantation. Recipients of OP9-DL1-derived T-cell precursors showed increased thymic cellularity and substantially improved donor T-cell chimerism (versus recipients of bone marrow or HSCs only). OP9-DL1-derived T-cell precursors gave rise to host-tolerant CD4+ and CD8+ populations with normal T-cell antigen receptor repertoires, cytokine secretion and proliferative responses to antigen. Administration of OP9-DL1-derived T-cell precursors increased resistance to infection with Listeria monocytogenes and mediated significant graft-versus-tumor (GVT) activity but not graft-versus-host disease (GVHD). We conclude that the adoptive transfer of OP9-DL1-derived T-cell precursors markedly enhances T-cell reconstitution after transplantation, resulting in GVT activity without GVHD. 相似文献
104.
Radhika Tatineni Kiran Kumar Doddapaneni Sailasree Dalavayi Santosh M. Kulkarni Lakshmi Narasu Mangamoori 《Process Biochemistry》2006,41(12):2464-2467
Artemisinin, a sesquiterpene lactone containing an endoperoxide bridge, isolated from Artemisia annua L. is effective against both drug resistant and cerebral malaria causing strains of Plasmodium falciparum. The relative low yields of artemisinin in plants are a serious limitation to the commercialization of the drug. An alternative approach by microbial bioconversion of arteannuin B to artemisinin was carried out by Microbacterium trichotecenolyticum isolated from soil. Crude enzyme extract from cell free extracts were capable of microbial bioconversion of arteannuin B, the immediate precursor of artemisinin, to artemisinin. Attempts have been made to partially purify the proteins involved in bioconversion by ion exchange chromatography. Detection of artemisinin was done by thin layer chromatography, and quantified by HPLC. 相似文献
105.
Kajekar R Undem BJ Myers AC 《American journal of physiology. Lung cellular and molecular physiology》2003,284(4):L581-L587
In vitro antigen challenge has multiple effects on the excitability of guinea pig bronchial parasympathetic ganglion neurons, including depolarization, causing phasic neurons to fire with a repetitive action potential pattern and potentiating synaptic transmission. In the present study, guinea pigs were passively sensitized to the antigen ovalbumin. After sensitization, the bronchi were prepared for in vitro electrophysiological intracellular recording of parasympathetic ganglia neurons to investigate the contribution of cyclooxygenase activation and prostanoids on parasympathetic nerve activity. Cyclooxygenase inhibition with either indomethacin or piroxicam before in vitro antigen challenge blocked the change in accommodation. These cyclooxygenase inhibitors also blocked the release of prostaglandin D(2) (PGD(2)) from bronchial tissue during antigen challenge. We also determined that PGE(2) and PGD(2) decreased the duration of the action potential after hyperpolarization, whereas PGF(2alpha) potentiated synaptic transmission. Thus prostaglandins released during antigen challenge have multiple effects on the excitability of guinea pig bronchial parasympathetic ganglia neurons, which may consequently affect the output from these neurons and thereby alter parasympathetic tone in the lower airways. 相似文献
106.
Expression,purification, and characterization of minimized chicken riboflavin carrier protein from a synthetic gene in Escherichia coli 总被引:1,自引:0,他引:1
Subramanian S Kondaiah P Radhakantha Adiga P 《Protein expression and purification》2002,26(2):284-289
Minimized proteins have long been used to elicit immune response to particular regions of a protein antigen. Most efforts to derive minimized proteins have employed synthetic peptide fragments. Here we describe molecular cloning and production of a minimized chicken riboflavin carrier protein (mini-RCP) sequence that harbours all the four neutralizing epitopes but lacks the sequences that otherwise elicit undesirable antibodies. The gene encoding mini-RCP is engineered by contiguous alignment of nucleotide sequences coding for selected epitopes of chicken RCP separated by leucyl alanine residues. The gene has been constructed from eight oligonucleotides by employing overlapping PCR strategy and expressed in Escherichia coli, using the T7 promoter system. The recombinant protein could be purified to homogeneity by a single step Ni2+ affinity chromatography. Western blot experiments using epitope specific antisera confirm that the corresponding linear amino acid sequences are available for immunorecognition in the engineered protein. This methodology enables continuous production and purification in bulk amounts of the minimized RCP as a source of candidate immunocontraceptive vaccine in mammals. 相似文献
107.
108.
Arginine decarboxylase (arginine carboxy-lyase EC 4.1.1.19) of Cucumis sativus cotyledons, has a pH optimum of 8.3 and a temperature optimum of 40°. Among the various plant hormones administered to excised cotyledons in culture, benzyladenine and its riboside were most effective in increasing the arginine decarboxylase activity and putrescine content. The enzyme activity and putrescine content were significantly increased on acid feeding of the cotyledons and decreased by KCl treatment. The KCl effect could be only partially reversed by benzyladenine. Abscisic acid inhibited cotyledon growth and also reduced arginine decarboxylase and putrescine levels. This effect was overcome by cytokinins. The half life of the enzyme using cycloheximide was 3.7 hr. Dibutyryl cyclic AMP and 5′-AMP also marginally stimulated the enzyme and putrescine levels. Mixing experiments indicate that there is neither a non-dialysable activator nor inhibitor of the enzyme. 相似文献
109.
Diamine oxidase (EC 1.4.3.6) was purified from 5-day-old etiolated seedlings ofLathyrus sativus by MnCl2 treatment, (NH4)2SO4 and acetone fractionations, DEAE-Sephadex chromatography followed by gel filtration on Sephadex G-200. A single step purification
of the enzyme was achieved by using an immunoaffinity column, wherein rabbit antibodies to the homogeneous diamine oxidase
were coupled to CNBr-activated Sepharose. The enzyme thus obtained was homogeneous by electrophoretic, immunological and ultracentrifugal
criteria. It had anM
r of 148,000 (6.46S) and was a dimer with similar sub-units (M
r 75,000). Amino acid analysis showed the absence of cysteine residues although it contained five disulphide bonds. The enzyme
had copper (2.7 g atom/mol enzyme) but was not a glycoprotein. No absorption maximum in the visible region was detectable.
Ethylenediamine 1,3-diaminopropane and histamine were potent competitive inhibitors for the substrate putrescine. The addition
of monospecific antibodies to the enzyme increased the Km for benzyl amine without any change in the Vmax Diamine oxidase from pea seedling, partially purified, exhibited complete crossreactivity with the antibodies to theL. sativus enzyme. 相似文献
110.
A diamine oxidase has been purified (ca 40-fold) from 5-day old etiolated seedlings of L. sativus by MnCl2 treatment, (NH4)2SO4 and Me2CO fractionations, positive adsorption on alumina Cγ-gel followed by column chromatography on DEAE-Sephadex. This cytosol enzyme oxidatively deaminates a number of aliphatic and aryl alkylamines but not histamine. NSD-1055, semicarbazide and other carbonyl reagents, α,α'bipyridyl, 1,10-phenanthroline and 8-hydroxyquinoline inhibit the enzyme. Pargyline, SKF trans-385, atabrine were without effect on the enzyme. 相似文献