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排序方式: 共有1352条查询结果,搜索用时 15 毫秒
31.
Bithalamic hyperintensity on T2-weighted MR: vascular causes and evaluation with MR angiography 总被引:1,自引:0,他引:1
PURPOSE: To determine whether MR angiography can be used to differentiate between the two vascular causes of bithalamic hyperintensity on T2-weighted MR images: "top of the basilar" artery occlusion and deep cerebral vein thrombosis. METHODS: A retrospective review identified six patients with bithalamic T2 hyperintensity of vascular causes. MR angiography was performed in four patients, MR angiography and conventional angiography in one patient, and conventional angiography in one patient. Data pertaining to clinical presentation and hospital course were collected. MR angiographic techniques were multislab overlapping three-dimensional time-of-flight, 2-D time-of-flight, and 2-D phase-contrast. RESULTS: Three cases of top of the basilar artery occlusion and three cases of deep cerebral vein thrombosis were recognized. In all cases, T2 hyperintensity in a vascular distribution suggested cerebral occlusive disease. Infarction involving the thalami and basal ganglia was present in two cases of deep cerebral vein thrombosis. Infarction of the thalami, mesodiencephalic region, and cerebellar hemispheres was present in two cases of basilar artery occlusion. Bithalamic infarction alone was seen in one case of deep cerebral vein thrombosis and one case of basilar artery occlusion. In the five cases in which MR angiography was used, this technique accurately distinguished the vessels involved (arterial or venous). CONCLUSION: MR angiography is a useful adjunct to MR imaging in the evaluation of bithalamic T2 hyperintensity. It does help distinguish between the two vascular causes: top of basilar artery occlusion and deep cerebral vein thrombosis. 相似文献
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33.
Integrins exhibit reversible changes in their ability to bind ligands and these changes enable transient cell adhesion. We recently showed that leukocyte integrin CR3 (complement receptor type three, CD11b/CD18, alpha m beta 2) may be purified in a form that is either capable or incapable of binding soluble, monomeric ligand and that "inactive" CR3 may be rendered capable of binding ligand by addition of an anti-CR3 mAb known as KIM-127 (Cai and Wright, JBC. 270: 14358, 1995). Here, we demonstrate that active CR3 may be rendered inactive by treatment of immobilized receptor with EDTA. EDTA-treated CR3 failed to bind ligand even in the presence of mM Ca2+ and Mg2+, suggesting that EDTA-treatment caused a change in the receptor that is not readily reversed. EDTA-treated receptor did, however, bind ligand upon addition of KIM-127 plus Mg2+ with an affinity (17.8 +/- 4.5 nM) similar to untreated, active receptor (12.5 +/- 4.7 nM). EDTA-treated CR3 thus exhibits the properties of inactive CR3, in which the ligand binding site is cryptic but subject to exposure by KIM-127. A candidate for the cryptic ligand binding site is the I-domain, a Mg2+-binding region in the alpha chain of CR3. We found that monomeric C3bi binds directly to recombinant I-domain in a Mg(2+)-dependent fashion with an affinity of 300 +/- 113 nM. These results thus suggest that CR3 may be inactivated by removing tightly bound divalent cation from a cryptic site in CR3. 相似文献
34.
KK M?kinen CY Chen PL M?kinen CA Bennett PJ Isokangas KP Isotupa HR Pape 《Canadian Metallurgical Quarterly》1996,30(3):180-188
The concern with nursing research in the future work of nurse graduates. Expectations from the viewpoint of the nurse researcher. Keeping in mind the concerns which occupy nurse researchers now and in the future, expectations are raised of the graduates of degree programmes in nursing science which are now also being established in the Federal Republic of Germany. This takes into account the structurally determined areas of self determined action in new fields of professional practice. Nurse graduates will be seen as "change agents" in their future areas of work and will have three essential aspects of involvement with nursing research: 1. they themselves will conduct research 2. they will receive, put into practice and transmit results of nursing research 3. they will initiate and commission nursing research projects. According to the broad topics of nursing research, requirements for nurses to act as professionals in their new working fields are formulated referring to the given structural conditions in Germany. 相似文献
35.
Jiang Wang Chunlei Liu Christian LeinenbachUlrich E. Klotz Peter J. UggowitzerJörg F. Löffler 《Calphad》2011,35(1):82-94
The Cu-Sn-Ti ternary system has been studied via experiments and thermodynamic modelling. In the experimental section, the composition of the alloys was selected based on the preliminary calculations and available literature data. Metallography, scanning electron microscopy and electron probe microanalysis were employed to analyse alloy samples prepared by arc-melting after annealing at 800 °C for 760 h. Solid phase relations at 800 °C were established. In contrast to earlier reports, the CuSn3Ti5 phase was interpreted as a binary intermetallic compound (Sn3Ti5) with extended Cu solubility. In the modelling section, three binary sub-systems were critically evaluated and updated according to the new experimental data and theoretical calculations reported in literature. According to their crystal structures and homogeneity ranges, appropriate sublattice models were proposed for SnTi3,SnTi2,Sn3Ti5 and Sn5Ti6. A set of self-consistent thermodynamic parameters for the Cu-Sn-Ti ternary system was obtained by considering the present experimental results and reported experimental information. The calculated results compare with the available experimental data to validate the present thermodynamic assessment. 相似文献
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37.
Molecular cloning, expression, and characterization of a functional single-chain Fv antibody to the mycotoxin zearalenone 总被引:1,自引:0,他引:1
Q Yuan JR Clarke HR Zhou JE Linz JJ Pestka LP Hart 《Canadian Metallurgical Quarterly》1997,63(1):263-269
The heavy-chain and kappa light-chain variable region genes of an antizearalenone hybridoma cell line (2G3-6E3-2E2) were isolated by PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a single-chain Fv (scFv) DNA fragment. The scFv DNA fragment was cloned into a phagemid (pCANTAB5E) and expressed as a fusion protein with E tag and phage M13 p3 in Escherichia coli TG1. In the presence of helper phage M13K07, the scFv fusion protein was displayed on the surfaces of recombinant phages. High-affinity scFv phages were enriched through affinity selection in microtiter wells coated with zearalenone-ovalbumin conjugate. The selected recombinant phages were used to infect E. coli HB2151 for the production of soluble scFv antibodies. One selected clone (pQY1.5) in HB2151 secreted a soluble scFv antibody (QY1.5) with a high zearalenone-binding affinity (concentration required for 50% inhibition of binding, 14 ng/ml), similar to that of parent monoclonal antibody in a competitive indirect enzyme-linked immunosorbent assay. However, scFv QY1.5 exhibited higher cross-reactivity with zearalenone analogs and had greater sensitivity to methanol destabilization than the parent monoclonal antibody did. Nucleotide sequence analyses revealed that the light-chain portion of scFv QY1.5 had a nucleotide sequence identity of 97% to a mouse germ line gene VK23.32 in mouse kappa light-chain variable region subgroup V, whereas the heavy-chain nucleotide sequence was classified as mouse heavy-chain subgroup III (D) but without any closely related members having highly homologous complementarity-determining region sequences. The potential of soluble scFv QY1.5 for routine screening of zearalenone and its analogs was demonstrated with zearalenone-spiked corn extracts. 相似文献
38.
Univ.-Prof. DI Dr. Helmut Habersack DI Marlene Haimann Ass. Prof. Dr. Sándor Baranya Prof. Dr. János Józsa Mag. Angelika Riegler Dr Christine Sindelar DI Marcel Liedermann Johanna Ficsor Gabriella Mohácsiné Simon HR DI Dr. Michael Hengl 《?sterreichische Wasser- und Abfallwirtschaft》2014,66(9-10):340-347
The multiple uses of the Danube River for navigation, hydropower production and as a drinking water supply influence its ecological quality. Flow restrictions due to regulation as well as impacts on the sediment regime such as retention in the catchment area and interruption of the sediment continuum result in changes of the hydromorphological structures and can produce major problems in the context of sediment management. In light of these facts, cross-border investigations of sediment transport at the Danube River are called for. As there are no uniform research approaches shared by Austria and Hungary, the EU-funded project SEDDON (Sediment Research and Management at the Danube River) aims to compare different monitoring and modeling techniques used to determine sediment transport, and to develop mutual solutions. Further, the laboratory equipment currently used for hydraulic model experiments is evaluated and a research channel with a free flowing discharge of up to 10 m3/s without pumping will be constructed, allowing large-scale joint laboratory tests concerning sediment to be performed. 相似文献
39.
李福刚 《沈阳理工大学学报》1995,(4)
介绍了跟踪式热平衡温度测量的原理:当检测头与被测体靠近时,通过对流换热形成梯度为零的温度场,因而二者温度相等。这种梯度为零的温度场是通过对检测头的一端制冷(或加热)跟踪被测体的温度形成的.最后给出了静态和动态实验的测试结果。 相似文献
40.
In the current era of critical-organ shortage, one of the most controversial questions facing transplantation teams is whether hepatic retransplantation, which has historically been associated with increased resource utilization and diminished survival, should be offered to a patient whose first allograft is failing. Retransplantation effectively denies access to orthotopic liver transplantation (OLT) to another candidate and further depletes an already-limited organ supply. The study group was comprised of 1,356 adults undergoing hepatic retransplantation in the United States between 1990 and 1996 as reported to the United Network for Organ Sharing (UNOS). We analyzed numerous donor and recipient variables and created Cox proportional-hazards models on 900 randomly chosen patients, validating the results on the remaining cohort. Five variables consistently provided significant predictive power and made up the final model: age, bilirubin, creatinine, UNOS status, and cause of graft failure. Although both hepatitis C seropositivity and donor age were significant by univariate and multivariate analyses, neither contributed independently to the estimation of prognosis when added to the final model. The final model was highly predictive of survival (whole model chi2 = 139.63). The risk scores for individual patients were calculated, and patients were assigned into low-, medium-, and high-risk groups (P <.00001). The low degree of uncertainty in the probability estimates as reflected by confidence intervals, even in our high-risk patients, underscores the applicability of our model as an adjunct to clinical judgment. We have developed and validated a model that uses five readily accessible "bedside" variables to accurately predict survival in patients undergoing liver retransplantation. 相似文献