排序方式: 共有21条查询结果,搜索用时 15 毫秒
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Roseane Borner Jo?o Bento-Torres Diego RV Souza Danyelle B Sadala Nonata Trevia José Augusto Farias Nara Lins Aline Passos Amanda Quintairos José Ant?nio Diniz Victor Hugh Perry Pedro Fernando Vasconcelos Colm Cunningham Cristovam W Pican?o-Diniz 《朊病毒》2011,5(3):215-227
Behavioral and neuropathological changes have been widely investigated in murine prion disease but stereological based unbiased estimates of key neuropathological features have not been carried out. After injections of ME7 infected (ME7) or normal brain homogenates (NBH) into dorsal CA1 of albino Swiss mice and C57BL6, we assessed behavioral changes on hippocampal-dependent tasks. We also estimated by optical fractionator at 15 and 18 weeks post-injections (w.p.i.) the total number of neurons, reactive astrocytes, activated microglia and perineuronal nets (PN) in the polymorphic layer of dentate gyrus (PolDG), CA1 and septum in albino Swiss mice. On average, early behavioral changes in albino Swiss mice start four weeks later than in C57BL6. Cluster and discriminant analysis of behavioral data in albino Swiss mice revealed that four of nine subjects start to change their behavior at 12 w.p.i. and reach terminal stage at 22 w.p.i and the remaining subjects start at 22 w.p.i. and reach terminal stage at 26 w.p.i. Biotinylated dextran-amine BDA-tracer experiments in mossy fiber pathway confirmed axonal degeneration and stereological data showed that early astrocytosis, microgliosis and reduction in the perineuronal nets are independent of a change in the number of neuronal cell bodies. Statistical analysis revealed that the septal region had greater levels of neuroinflammation and extracellular matrix damage than CA1. This stereological and multivariate analysis at early stages of disease in an outbred model of prion disease provided new insights connecting behavioral changes and neuroinflammation and seems to be important to understand the mechanisms of prion disease progression.Key words: prion disease, optical fractionator, neuropathology, behavioral changes, albino Swiss mice 相似文献
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Nagaraj P. Shetti 《Inorganica chimica acta》2009,362(7):2270-2442
The oxidation of an anticancer drug 5-fluorouracil (5-FU) by diperiodatoargentate(III) (DPA) was carried out both in the absence and presence of osmium(VIII) catalyst in alkaline medium at 27 °C and a constant ionic strength of 0.20 mol dm−3 spectrophotometrically attached with HI-TECH SFA-12 stopped flow accessory. The oxidation products in both the cases were identified as fluoroketene and Ag(I). The stoichiometry is same in both cases, i.e., [5-FU]:[DPA] = 1:1. The reaction was of first order in both catalysed and uncatalysed cases, with respect to [DPA] and was less than unit order in [5-FU] and negative fraction in [alkali]. The order in Os(VIII) was unity. In both cases [Ag(H3IO6)2]− itself is the active species of DPA. The uncatalysed reaction in alkaline medium has been shown to proceed via a DPA-5-fluorouracil complex, which decomposes in a rate determining step to give the products. In catalysed reaction, it has been shown to proceed via a Os(VIII)-5-fluorouracil complex, which further reacts with one molecule of DPA in a rate determining step to give the products. The reaction constants involved in the different steps of the mechanisms were calculated for both the reactions. The catalytic constant (kCat.const.) was also calculated for catalysed reaction at different temperatures. The activation parameters with respect to slow step of the mechanisms were computed and discussed for both the cases. The thermodynamic quantities were also determined for both reactions. 相似文献
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Ian PG Marshall Dusty RV Berggren Mohammad F Azizian Luke C Burow Lewis Semprini Alfred M Spormann 《The ISME journal》2012,6(4):814-826
We developed a broad-ranging method for identifying key hydrogen-producing and consuming microorganisms through analysis of hydrogenase gene content and expression in complex anaerobic microbial communities. The method is based on a tiling hydrogenase gene oligonucleotide DNA microarray (Hydrogenase Chip), which implements a high number of probes per gene by tiling probe sequences across genes of interest at 1.67 × –2 × coverage. This design favors the avoidance of false positive gene identification in samples of DNA or RNA extracted from complex microbial communities. We applied this technique to interrogate interspecies hydrogen transfer in complex communities in (i) lab-scale reductive dehalogenating microcosms enabling us to delineate key H2-consuming microorganisms, and (ii) hydrogen-generating microbial mats where we found evidence for significant H2 production by cyanobacteria. Independent quantitative PCR analysis on selected hydrogenase genes showed that this Hydrogenase Chip technique is semiquantitative. We also determined that as microbial community complexity increases, specificity must be traded for sensitivity in analyzing data from tiling DNA microarrays. 相似文献
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LILIAN JÄRVEKÜLG JÜRI SõBER RIIVO SINIJÄRV INDREK TOOTS MART SAARMA 《The Annals of applied biology》1989,114(2):279-291
Mouse monoclonal antibodies (MAbs) specific for potato virus M (PVM) were prepared and the properties of three of them were studied. MAb M4C1 is IgG2b, it binds with high affinity to PVM coat protein, to purified virus preparations and recognises PVM in infected potato leaves and tubers. MAb M6D5 is IgG2a and also reacts with PVM coat protein, purified PVM and with PVM in potato leaf and tuber extracts. In double-antibody sandwich ELISA (DAS ELISA) MAbs M4C1 and M6D5 reacted with all 17 PVM isolates tested. MAb M7 is IgG2b and recognises PVM only in indirect dot ELISA on nitrocellulose filters and viral coat protein on Western blots. MAbs against PVM were used as capture antibodies and europium-labelled MAbs as conjugates in time-resolved fluoroimmunoassay (EuTRFIA). The standard EuTRFIA curve of PVM detection is approximately linear over a range of PVM concentrations from 0.5 ng/ml to 1000 ng/ml. The lowest PVM concentration detectable in EuTRFIA was 0.5 ng/ml and correspondingly 6 ng/ml in DAS ELISA. The use of the europium chelate label allows PVM detection in potato leaf and tuber sap at dilutions greater than 10--4 with very low background fluorescence. EuTRFIA with MAbs, with either one or two incubations is about 10–20 times more sensitive for PVM detection than is DAS ELISA. PVM and PVX, mixed with healthy potato tuber sap, were simultaneously tested in a single sample at concentrations lower than 10 ng/ml by double-label TRFIA using europium-labelled MAbs to PVM and samarium-labelled MAbs to PVX. 相似文献
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Martin Wilmking Marieke van der Maaten‐Theunissen Ernst van der Maaten Tobias Scharnweber Allan Buras Christine Biermann Marina Gurskaya Martin Hallinger Jelena Lange Rohan Shetti Marko Smiljanic Mario Trouillier 《Global Change Biology》2020,26(6):3212-3220
Tree‐ring records provide global high‐resolution information on tree‐species responses to global change, forest carbon and water dynamics, and past climate variability and extremes. The underlying assumption is a stationary (time‐stable), quasi‐linear relationship between tree growth and environment, which however conflicts with basic ecological and evolutionary theory. Indeed, our global assessment of the relevant tree‐ring literature demonstrates non‐stationarity in the majority of tested cases, not limited to specific proxies, environmental parameters, regions or species. Non‐stationarity likely represents the general nature of the relationship between tree‐growth proxies and environment. Studies assuming stationarity however score two times more citations influencing other fields of science and the science–policy interface. To reconcile ecological reality with the application of tree‐ring proxies for climate or environmental estimates, we provide a clarification of the stationarity concept, propose a simple confidence framework for the re‐evaluation of existing studies and recommend the use of a new statistical tool to detect non‐stationarity in tree‐ring proxies. Our contribution is meant to stimulate and facilitate discussion in light of our results to help increase confidence in tree‐ring‐based climate and environmental estimates for science, the public and policymakers. 相似文献
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Ananworanich J Schuetz A Vandergeeten C Sereti I de Souza M Rerknimitr R Dewar R Marovich M van Griensven F Sekaly R Pinyakorn S Phanuphak N Trichavaroj R Rutvisuttinunt W Chomchey N Paris R Peel S Valcour V Maldarelli F Chomont N Michael N Phanuphak P Kim JH;RV/SEARCH Study Group 《PloS one》2012,7(3):e33948