Bone morphogenetic proteins （Bmp） are well-known to induce bone formation following chondrogenesis, but the direct role of Bmp signaling in the osteoblast lineage is not completely understood. We have recently shown...Bone morphogenetic proteins （Bmp） are well-known to induce bone formation following chondrogenesis, but the direct role of Bmp signaling in the osteoblast lineage is not completely understood. We have recently shown that deletion of the receptor Bmprla in the osteoblast lineage with Dmpl-Cre reduces osteoblast activity in general but stimulates proliferation of preosteoblasts specifically in the cancellous bone region, resulting in diminished periosteal bone growth juxtaposed with excessive cancellous bone formation. Because expression of sclerostin （SOST）, a secreted Wnt antagonist, is notably reduced in the Bmprla- deficient osteocytes, we have genetically tested the hypothesis that increased Wnt signaling might mediate the increase in cancellous bone formation in response to Bmprla deletion. Forced expression of human SOST from a Dmpl promoter fragment partially rescues preosteoblast hyperproliferation and cancellous bone overgrowth in the Bmprla mutant mice, demonstrating functional interaction between Bmp and Wnt signaling in the cancellous bone compat^a-tent. To test whether increased Wnt signaling can compensate for the defect in periosteal growth caused by Bmprla deletion, we have generated compound mutants harboring a hyperactive mutation （A214V） in the Wnt receptor Lrp5. However, the mutant Lrp5 does not restore periosteal bone growth in the Bmprla-deficient mice. Thus, Bmp signaling restricts cancellous bone accrual partly through induction of SOST that limits preosteoblast proliferation, but promotes periosteal bone growth apparently independently of Wnt activation.展开更多
In the application of cancellous bone ultrasound diagnosis based on backscattering method, it is of great importance to estimate fast and accurately whether the valid backscattering signal exists in the received signa...In the application of cancellous bone ultrasound diagnosis based on backscattering method, it is of great importance to estimate fast and accurately whether the valid backscattering signal exists in the received signal. We propose a fast estimation method based on spectrum entropy method. With 984 records of adult calcaneus clinical data, we estimate the validity of the backscatter signal using this method. The results of the proposed method and the results of experience-base judgement were compared and analyzed. And two key parameters, the signal range length and the segment number of the spectrum entropy, were analyzed. The results show when the signal range length is 13 I^s and the segment number is 15 20, this method can get the best result （accuracy〉95%, sensitivity〉99%, specificity〉87%）, while taking little calculation time （1.5 ms）. Therefore, this spectrum entropy method can satisfy the accuracy and real-time requirements in the ultrasonic estimation for cancellous bone.展开更多
The use of global navigation satellite system signals reflected by the sea surface as a remote sensing tool has received considerable attention for over a decade. However, in signal detection processing, the direct-pa...The use of global navigation satellite system signals reflected by the sea surface as a remote sensing tool has received considerable attention for over a decade. However, in signal detection processing, the direct-path interference can potentially introduce a bigger obstacle to ocean surface detection than other interferences, such as clutter and radio signals. In order to improve retrieval of the ocean surface parameters, the direct-path interference signals have to be suppressed. The interference suppression based on the improved subspace projection algorithm is put forward in this paper. First of all, the interferential signal is acquired and tracked, then according to the acquired interferential signal parameter, the corresponding disturbance subspace is constructed. Finally, the interference is eliminated using the improved subspace block projection. This method can not only reduce the influence of interferential performance by the tracking error but also decrease computation greatly. It suits the changeable environment and the multi-data sample situation. The analysis of the simulated results has confirmed the validity of this method and provided a basis for the following system optimization design.展开更多
基金supported by NIH grants AR060456 and AR055923(FL)partly supported by P30 AR057235(Washington University Musculoskeletal Research Center)+1 种基金supported by the George O’Brien Center for Kidney Disease Research(P30 DK079333)Kidney translational Research Core and the Renal Division at the Washington University School of Medicine
文摘Bone morphogenetic proteins （Bmp） are well-known to induce bone formation following chondrogenesis, but the direct role of Bmp signaling in the osteoblast lineage is not completely understood. We have recently shown that deletion of the receptor Bmprla in the osteoblast lineage with Dmpl-Cre reduces osteoblast activity in general but stimulates proliferation of preosteoblasts specifically in the cancellous bone region, resulting in diminished periosteal bone growth juxtaposed with excessive cancellous bone formation. Because expression of sclerostin （SOST）, a secreted Wnt antagonist, is notably reduced in the Bmprla- deficient osteocytes, we have genetically tested the hypothesis that increased Wnt signaling might mediate the increase in cancellous bone formation in response to Bmprla deletion. Forced expression of human SOST from a Dmpl promoter fragment partially rescues preosteoblast hyperproliferation and cancellous bone overgrowth in the Bmprla mutant mice, demonstrating functional interaction between Bmp and Wnt signaling in the cancellous bone compat^a-tent. To test whether increased Wnt signaling can compensate for the defect in periosteal growth caused by Bmprla deletion, we have generated compound mutants harboring a hyperactive mutation （A214V） in the Wnt receptor Lrp5. However, the mutant Lrp5 does not restore periosteal bone growth in the Bmprla-deficient mice. Thus, Bmp signaling restricts cancellous bone accrual partly through induction of SOST that limits preosteoblast proliferation, but promotes periosteal bone growth apparently independently of Wnt activation.
基金supported by the National Natural Science Foundation of China(11327405,11525416,11604054,11504057)
文摘In the application of cancellous bone ultrasound diagnosis based on backscattering method, it is of great importance to estimate fast and accurately whether the valid backscattering signal exists in the received signal. We propose a fast estimation method based on spectrum entropy method. With 984 records of adult calcaneus clinical data, we estimate the validity of the backscatter signal using this method. The results of the proposed method and the results of experience-base judgement were compared and analyzed. And two key parameters, the signal range length and the segment number of the spectrum entropy, were analyzed. The results show when the signal range length is 13 I^s and the segment number is 15 20, this method can get the best result （accuracy〉95%, sensitivity〉99%, specificity〉87%）, while taking little calculation time （1.5 ms）. Therefore, this spectrum entropy method can satisfy the accuracy and real-time requirements in the ultrasonic estimation for cancellous bone.
文摘The use of global navigation satellite system signals reflected by the sea surface as a remote sensing tool has received considerable attention for over a decade. However, in signal detection processing, the direct-path interference can potentially introduce a bigger obstacle to ocean surface detection than other interferences, such as clutter and radio signals. In order to improve retrieval of the ocean surface parameters, the direct-path interference signals have to be suppressed. The interference suppression based on the improved subspace projection algorithm is put forward in this paper. First of all, the interferential signal is acquired and tracked, then according to the acquired interferential signal parameter, the corresponding disturbance subspace is constructed. Finally, the interference is eliminated using the improved subspace block projection. This method can not only reduce the influence of interferential performance by the tracking error but also decrease computation greatly. It suits the changeable environment and the multi-data sample situation. The analysis of the simulated results has confirmed the validity of this method and provided a basis for the following system optimization design.
