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排序方式: 共有399条查询结果,搜索用时 15 毫秒
91.
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92.
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
93.
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
94.
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
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Desikan R Cheung MK Bright J Henson D Hancock JT Neill SJ 《Journal of experimental botany》2004,55(395):205-212
Increased synthesis and redistribution of the phytohormone abscisic acid (ABA) in response to water deficit stress initiates an intricate network of signalling pathways in guard cells leading to stomatal closure. Despite the large number of ABA signalling intermediates that are known in guard cells, new discoveries are still being made. Recently, the reactive oxygen species hydrogen peroxide (H2O2) and the reactive nitrogen species nitric oxide (NO) have been identified as key molecules regulating ABA-induced stomatal closure in various species. As with many other physiological responses in which H2O2 and NO are involved, stomatal closure in response to ABA also appears to require the tandem synthesis and action of both these signalling molecules. Recent pharmacological and genetic data have identified NADPH oxidase as a source of H2O2, whilst nitrate reductase has been identified as a source of NO in Arabidopsis guard cells. Some signalling components positioned downstream of H2O2 and NO are calcium, protein kinases and cyclic GMP. However, the exact interaction between the various signalling components in response to H2O2 and NO in guard cells remains to be established. 相似文献
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Bhavana L Ajimon VJ Radhika SL Sindhu M Iyer CS 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,803(2):363-366
Thyroxine (3,5,3',5'-tetraiodo thyronine) is administered to patients suffering from endemic goiter as also in cases of non-iodine deficient ethiology and hypothyroidism. It is suggested that the uptake of thyroxine can be monitored by assessing the levels of the same in the urine of patients under treatment. For the purpose, a highly sensitive and selective ion chromatographic procedure is developed. The sample of urine is treated with sodium hydroxide and UV irradiated to convert iodine in thyroxine to iodide. Subsequently, iodide is separated on an anion exchanger AS 4A column using 50 mM NaOH as the eluent and determined spectrophotometrically at 226 nm. 相似文献