Bioresorbable vascular scaffolds (BVS), the next step in the continuum of minimally invasive vascular interventions present new opportunities for patients and clinicians but challenges as well. As they are comprised of polymeric materials standard imaging is challenging. This is especially problematic as modalities like optical coherence tomography (OCT) become more prevalent in cardiology. OCT, a light-based intracoronary imaging technique, provides cross-sectional images of plaque and luminal morphology. Until recently segmentation of OCT images for BVS struts was performed manually by experts. However, this process is time consuming and not tractable for large amounts of patient data. Several automated methods exist to segment metallic stents, which do not apply to the newer BVS. Given this current limitation coupled with the emerging popularity of the BVS technology, it is crucial to develop an automated methodology to segment BVS struts in OCT images. The objective of this paper is to develop a novel BVS strut detection method in intracoronary OCT images. First, we pre-process the image to remove imaging artifacts. Then, we use a K-means clustering algorithm to automatically segment the image. Finally, we isolate the stent struts from the rest of the image. The accuracy of the proposed method was evaluated using expert estimations on 658 annotated images acquired from 7 patients at the time of coronary arterial interventions. Our proposed methodology has a positive predictive value of 0.93, a Pearson Correlation coefficient of 0.94, and a F1 score of 0.92. The proposed methodology allows for rapid, accurate, and fully automated segmentation of BVS struts in OCT images.
Endothelial dysfunction has found to be related to cardiovascular disease. In the study, we assessed the endothelial flow-mediated vasodilatation (FMD) in three different-sized vessels. The study included 27 healthy volunteers who were asked to experience a 3-minute occlusion of brachial arteries. We found that FMD of radial arteries using the low-pressure oscillometry was significantly larger than that of small arteries together with microvessels in fingers using the photoplethysmography (PPG) (122 +/- 64 versus 87 +/- 56, p < 0.05). In addition, FMD measurements with PPG and laser Doppler flowmetry tended to negatively correlate with pulse pressure and pulse wave velocity. With a less coefficient of variations, the proposed low-pressure oscillometry may be a means for assessing the vascular endothelial function of peripheral circulation.
The use of small specific molecules including nutrients and pharmacological agents has been tried in the modulation of stem cells differentiation to obtain insulin secreting cells. The aim of this study was to investigate the ability of nano-sized collagen I molecules to enhance the differentiation of MSCs toward insulin-secreting cells in combination with nicotinamide and exendin-4. The preliminary results demonstrated that enhanced differentiation of MSCs towards insulin-secreting cells were achieved after an extra treatment with nano-sized collagen I molecules from the RT-PCR analysis and immunofluorescence staining of PDX-1, Nkx-6.1 and insulin markers.
Degeneration or injuries on articular cartilage is hard to self-repair. Physical stimulation, such as electrical, ultrasound or shear stress could be used for promoting chondrocytes proliferation and articular cartilage self-repair. Previous research on ultrasound stimulation used high frequency ultrasound. In this study, low frequency ultrasound stimulation is proposed as the treatment of osteoarthritis. An osteoarthritis model using New Zealand White rabbits was used to investigate whether low frequency ultrasound stimulation of 32.8 kHz is effective for the regeneration of articular cartilage. The evidence shows that low frequency ultrasound of 100mW can promote the regeneration of articular cartilage.
A challenging problem in dental implant surgery is to evaluate the stability of the implant. In this simulation study, an experimental phantom is used to represent a jawbone with a dental implant. It is made of a little pool filled with soft-tissue equivalent material and a disc of fresh Oakwood with a metal screw. Varying levels of contact between screw and wood are simulated by screwing in or out the screw. Initially, the screw is screwed in and fixed firmly in wood. Thereafter, the screw is screwed out, a half turn each time, to increase the gap gradually between wood and screw. Pulse-echo ultrasound is used and the power spectra of the received echo-signals are computed. These spectra are normalized then analyzed by using the partial least squares method to estimate the corresponding implant stiffness grade in terms of number of turns when beginning from the initial tight-screw state then screwing out the screw. A coefficient of determination R2 of 96.4% and a mean absolute error of ±0.23 turns are achieved when comparing real and estimated values of stiffness grades, indicating the efficiency of this approach.
The new protocol for sequencing the messenger RNA in a cell, named RNA-seq produce millions of short sequence fragments. Next Generation Sequencing technology allows more accurate analysis but increase needs in term of computational resources. This paper describes the optimization of a RNA-seq analysis pipeline devoted to splicing variants detection, aimed at reducing computation time and providing a multi-user/multisample environment. This work brings two main contributions. First, we optimized a well-known algorithm called TopHat by parallelizing some sequential mapping steps. Second, we designed and implemented a hybrid virtual GRID infrastructure allowing to efficiently execute multiple instances of TopHat running on different samples or on behalf of different users, thus optimizing the overall execution time and enabling a flexible multi-user environment
Considering that proteins with similar 3D structures have similar functions or biological actions, classification of proteins based on 3D structure can lead biologists to the investigation of new protein's structural, evolutionary, and functional relatedness. However, 3D protein structure remains a hard task, because different protein classes may have different discriminant features and unbalanced data distribution. This means that standard pairwise distance computation like Euclidean distance does not always have equal strength on features in the feature space. Most existing 3D protein structure classification methods relies on a K-Nearest Neighbor (KNN) classifier with a Euclidean distance, which do not consider the above factors and results on low classification accuracy. To improve the KNN for 3D protein structure classification, we propose the Class Conditional Distance Metric (CCDM), which takes into account the within-class neighborhood distribution of the protein descriptors and iteratively estimates distance update terms, thereby modifying the within-class neighborhood structure. Experimental results show that our approach gives significantly better results than a standard KNN classifier and is comparable the state of the art in terms of accuracy on the FSSP/DALI protein data set.
Inspection, auscultation and olfaction, inquiring, palpation, called si-zhen in Chinese, are four diagnostic methods in Traditional Chinese Medicine (TCM) which reflect a general identification to the variation of human body done by subjective thinking. Face diagnosis is one of the most precious and widely used diagnostic methods in inspection, but with a great deal of subjective information and experiential knowledge of medical physicians in the past. In order to meet the requirement of face diagnosis objectivity, combining with TCM theory and Chinese medical physicians' clinical experience, the framework of assistant face diagnosis is designed, and several methods are proposed to do the objective analysis of face feature and expression, including facial zang-fu respective localization, complexion extraction and classification, complexion transfer and eye expression analysis and eye-sight brightness computing, making use of biometric technology and computer image processing. Experimental results show that these methods are effective and have practical significant for assisting Chinese medical physicians to analyze diagnostic information objectively, as well as a theoretical and methodological support for the quantification, analysis and processing on the face diagnostic information in TCM.
Electromyography (EMG) has been widely used as control commands for prosthesis, powered exoskeletons and rehabilitative robots. In this paper, an EMG-driven state-space model is developed to estimate joint angular velocities and angles throughout elbow flexion/extension. The state equation of the model combines the Hill-based muscle model with the forward dynamics of joint movement, and expresses the kinematic variables as a function of neural activation levels. Then, EMG features including integral of absolute value and waveform length are extracted, and two quadratic equations which associate the kinematic variables with EMG features are fitted to represent the measurement equation. Based on the proposed model, the joint angular velocities and angles are estimated just using the EMG signals with the Extended Kalman Filter (EKF), and the estimation results are used to control a manipulator. The experimental results demonstrate the efficiency of EMG-based motion control with the proposed model.
The protein crystallization is a complex physical and chemical process. The high-quality protein crystal is still a persistent bottleneck to the application of X-ray crystallography in structural biology. The additives may promote formation of crystal nucleus and subsequent growth in protein crystallization. As a distinct material, ionic liquids (ILs) have aroused great attentions and interests for protein crystallization due to their unique properties. In this paper, the application of ILs into protein crystallization has been reviewed in this paper. A research about lysozyme morphology control by ionic liquids, as crystal growth template, in aqueous solutions has been performed. It is worth noting that ILs encourage changes in some cases in terms of growth morphology and crystal size. The effect of ILs on lysozyme growth morphology can be attributed to changing interaction among lysozyme molecules in aqueous solutions. A study on molecular interaction in the presence ILs based on solubility and Raman spectroscopy were performed. Our study is especially helpful to control crystal growth and morphology for protein and to gain initial insight into the preparation of high quality crystal and the development of new crystal form as well as the design optimization of protein crystallization.
An efficient microwave-assisted extraction (MAE) technique has been developed to recover polysaccharide from Palmaria palmata through an orthogonal experiment (L9(3)4). The content of polysaccharide was determined by phenol-sulphuric acid method and the antioxidant activities were evaluated by DPPH/ Hydroxyl radical-scavenging activity. Under the optimum parameters of microwave power of 500W, extraction temperature of 70°C, extraction time of 10 min and solid-to liquid ratio of 1:70, the yield of crude polysaccharides (CP) reached to 17.01%. The CP was further purified by DEAE52 cellulose ion-exchange chromatography to afford three fractions (Fl to F3). F12 with higher purity was isolated from Fl fraction using Sephadex G-75 gel chromatography. Using the vitamin C as the positive control, the antioxidant activities of CP and F12 were investigated. In the antioxidant tests, CP and F12 exhibited higher DPPH radical scavenging activity and hydroxyl radical scavenging activity than vitamin C in the concentrations ranges of 2.5 μg/mL to 25.0 μg/mL and 9.3 μg/mL to 93.0 μg/mL, respectively. The results demonstrated potential antioxidant activities effect of polysaccharide, providing scientific support for the empirical use of polysaccharide as an antioxidant for diseases caused by reactive oxygen species.
The phylogenetic median-joining (MJ) network algorithm which offers new features compared with reduced median (RM) network algorithm in that it can handle larger sets of genetic data, as well as multistate data such as amino acid sequences. We investigated phylogeny of 211 goat individuals from South China based on the MJ network analysis of mtDNA D-loop HVI fragments (481 bp) in conjunction with corresponding 33 sequences as references. The goats from South China were classified into only two genetic lineages (lineage A and lineage B). No haplotypes of Chinese goats were included in lineage C, lineage D, lineage F or lineage G. One hundred and sixty-six goat individuals belonged to one lineage A, and forty-five belonged to lineage B. Therefore, we proposed that goats from South China were originated from lineage A and lineage B in matrilineal lineages. The population from lineage A had experienced population expansion, while the those from lineage B had not experienced population expansion.
Correspondence problem is a basic problem in stereoscopic vision, but it still remain unsolved for the Wheatstone-Panum limiting case. By replacing the straight lines in traditional stimulus configurations with fold lines that have characteristics of both line and plane, a kind of fold-line Wheatstone-Panum configuration of large horizontal scale are created and slant effect can therefore be used as the index of dichoptic fusion. The results show that two fold-lines are perceived slant consistently, which provides solid evidence for double fusion in the Wheatstone-Panum limiting case.
Ultrasonic scan conversion (SC) is one of the most important and widely-used technology in Medical Ultrasound Imaging. However, real-time processing of SC is computationally intensive, involving in calculation of inverse tangents, square roots to determine the scanning angle and depth of a beam followed by interpolation both in axial and lateral directions. In this paper, a very efficient implementation of ultrasonic scan conversion on the Compute Unified Device Architecture (CUDA™) platform developed by NVIDIA® and using the interoperability of Direct3D (D3D) and CUDA to display is presented. By exploiting the implicit parallelism and reasonable performance optimization strategies based on the graphics hardware, this parallel scan conversion algorithm obtains a high speed up. It achieves a frame rate of about more than 746 fps with the picture size of 3121* 936, which is about 300 times faster than the CPU implementation.
This paper present a low-cost wearable ultrasound bladder volume measurement and alarm system based on ARM9 and DSP. The system used a new volume computing method to estimate bladder volume based on the ultrasound echo obtained by only one phased-array ultrasonic transducer. The main signal processing task of ultrasound echo are performed using a DSP chip. The estimated value of bladder volume was transmitted to an alarm system based on Zigbee radio link. The system can be used for continuous monitoring of bladder volume and nursing on unconsciousness elders, handicapped with spinal cord injury, other urological patients, and children with nocturnal enuresis through setting alarm threshold.
Because of its non-destructive, real-time and ease of use, medical ultrasound becomes an important instrument of modern medical imaging modalities. Due to unresolved tissue scatterers limited by the resolution of the ultrasound probe, the formed image shows granular-like speckle noise which will deteriorate the quality of ultrasound images and result in difficulties in diagnosis. In order to reduce the speckle noise, this paper presents a bilateral filtering adjusted from the detection of speckle statistics derived from local histogram matching. The proposed algorithm can reduce the speckle noise and, at the same time, maintain the tissue structure. Ultrasound phantom testing and in vivo imaging show that the proposed method can improve the quality of ultrasound image in terms of tissue SNR and CNR values.
In HIFU therapy, it is very important to determine the ultrasound attenuation of different tissue from skin to target in HIFU beampath for predicting in advance the dose. So the reduction in acoustic radiation force in the presence of different tissue in HIFU beampath has been studied by a radiation force method. At a room temperature 20°C, the acoustic radiation force in the presence and absence of the prepared different tissue such as bovine liver of various thickness, skin, intercostal tissue closed to liver (including skin, fat, intercostal muscle, ribs and parietal pleura) and ribs in front of absorber in degassed water was measured at same acoustic power at transducer surface. Then the ratio of radiation force in the presence of different tissue relative to degassed water in HIFU beampath and the ultrasound attenuation were calculated. The ratio of radiation force in the presence of skin, intercostal tissue and ribs of pig relative to degassed water in HIFU beampath was 10%, 85.5% and 57.5% respectively. The ultrasound attenuation coefficient α in bovine liver was shown to be frequency f dependent, fitting the equation as follows α=0.43f 1.05 [dB.cm -1 .s 1.05 ]. The results showed that the ultrasound energy was attenuated markedly when HIFU traveled through intercostal tissue, especially ribs in HIFU beampath. This work offered experimental data that should be useful for future HIFU dosage studies.
Microarrays have become an important technology for the global analysis of gene expression in organisms. For discovery of differentially expressed genes, many cDNA microarray experiments gave a fixed threshold based on a fold change of signal intensity in relative expression level and/or a P value, the deviation of the fixed threshold could be observed by microarray experiments of self-versus-self hybridization. In order to accurately identify differentially expressed genes in two-channel microarray, control experiments through the self-versus-self hybridizations were performed with wheat cDNA microarrays in this study, distribution of extremes of expression levels was obtained from data analysis of the control experiments, and a threshold level was assigned based on the moment distribution method, the differentially expressed genes can be identified when the changes of expression levels of a gene at different treatments falls outside the threshold. This method could be appropriate to estimate the threshold limits and can be applied for cDNA microarray.
Objective To know the status of organic pollution in Urumqi surface water and treated water. Methods In early August 2009, 20L water were collected from the three main water plants respectively in Urumqi. According to the mass spectrums and the NIST library researching, organic compounds were identified. The relative quantities of the organic compounds were calculated by the area of peaks of the organic compounds. Conclusion 39 varieties of 8 categories water organisms were detected in the surface water and the treated water. Alkanes, esters, carboxylic acids, aromatic compounds were detected. The quantities of carboxylic organic compounds were detected in the largest.
