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1.
The goal of this study was to develop a new implantable transducer for measuring anterior cruciate ligament (ACL) graft tension postoperatively in patients who have undergone ACL reconstructive surgery. A unique approach was taken of integrating the transducer into a femoral fixation device. To devise a practical in vivo calibration protocol for the fixation device transducer (FDT), several hypotheses were investigated: (1) The use of a cable versus the actual graft as the means for applying load to the FDT during calibration has no significant effect on the accuracy of the FDT tension measurements; (2) the number of flexion angles at which the device is calibrated has no significant effect on the accuracy of the FDT measurements; (3) the friction between the graft and femoral tunnel has no significant effect on measurement accuracy. To provide data for testing these hypotheses, the FDT was first calibrated with both a cable and a graft over the full range of flexion. Then graft tension was measured simultaneously with both the FDT on the femoral side and load cells, which were connected to the graft on the tibial side, as five cadaver knees were loaded externally. Measurements were made with both standard and overdrilled tunnels. The error in the FDT tension measurements was the difference between the graft tension measured by the FDT and the load cells. Results of the statistical analyses showed that neither the means of applying the calibration load, the number of flexion angles used for calibration, nor the tunnel size had a significant effect on the accuracy of the FDT. Thus a cable may be used instead of the graft to transmit loads to the FDT during calibration, thus simplifying the procedure. Accurate calibration requires data from just three flexion angles of 0, 45, and 90 deg and a curve fit to obtain a calibration curve over a continuous range of flexion within the limits of this angle group. Since friction did not adversely affect the measurement accuracy of the FDT, the femoral tunnel can be drilled to match the diameter of the graft and does not need to be overdrilled. Following these procedures, the error in measuring graft tension with the FDT averages less than 10 percent relative to a full-scale load of 257 N. 相似文献
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A composite transposon 3'' to the cow fetal globin gene binds a sequence specific factor. 总被引:2,自引:2,他引:0 下载免费PDF全文
Two unusual sequence organizations were found within the beta-globin locus of the cow. Each was a composite, consisting of closely linked Alu-type repeats with a short stretch of genomic non-repetitive sequence, called a lagan, sandwiched between. One lagan was found 3' to the fetal globin gene, while the second lay between the adult globin gene and a globin pseudogene. Southern blot analysis indicated that both lagans appeared twice within the cow haploid genome, with the second copies lying outside the cow beta-globin locus. One of these non-globin locus homologues was cloned and subjected to sequence analysis. Comparison of the DNA sequence data showed that the lagan-Alu composite was transposed as a unit. The lagan 3' to the cow fetal globin gene contains the recognition site for a sequence specific DNA binding factor. This factor was present in extracts from fetal, but not from adult cow tissues. 相似文献
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Ruth Duncan Pavla Rejmanova Jindrich Kopeček John B. Lloyd 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(1):143-150
Synthetic 125I-labelled N-(2-hydroxypropyl)methacrylamide copolymers containing four different, potentially degradable peptidyl side chains were incubated with rat visceral yolk sacs cultured in vitro. All copolymers were captured by fluid-phase pinocytosis and three of the side chains were susceptible to lysosomal hydrolysis, resulting in release of [125I]iodotyrosine back into the culture medium. Uptake and degradation was completely inhibited by 2,4-dinitrophenol. The thiol-proteinase inhibitor leupeptin did not affect the rate of pinocytosis, but caused different degrees of inhibition of hydrolysis depending on side chain composition. 相似文献
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Inhibition of prostaglandin F 2a or LH induced luteolysis in the pseudopregnant rabbit by 17 -estradiol 总被引:1,自引:0,他引:1
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Duncan T. Patten 《American journal of botany》1978,65(8):891-895
During years with good winter rainfall, ephemeral plants can contribute considerably to primary production in the upper Sonoran Desert. This study was designed to compare ephemeral community productivity and production efficiency within the different microhabitats created by trees, shrubs and open spaces in a Sonoran Desert ecosystem. Ephemerals were periodically harvested in the different habitats and dried for biomass and caloric determinations. The caloric data were compared to total solar input into the different microhabitats in order to determine production efficiencies of each stand. Productivity rates were also determined for the total community for the sample period, winters of 1972-74. Both productivity and production efficiency were highest under the shade of Cercidium. The highest production efficiency occurring in the shaded sites was 5.03% which approaches the theoretical maximum photosynthetic efficiency level. The production efficiency of the entire ephemeral community for the whole growing season was only 0.17% during an optimal year, demonstrating the influence of the environment in the interspaces on productivity and solar conversion in the desert. 相似文献
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