Most studies addressing the specificity of meridians and acupuncture points have focused mainly on the different neural effects of acupuncture at different points in healthy individuals. This study examined the effect...Most studies addressing the specificity of meridians and acupuncture points have focused mainly on the different neural effects of acupuncture at different points in healthy individuals. This study examined the effects of acupuncture on brain function in a pathological context. Sixteen patients with ischemic stroke were randomly assigned to true point group (true acupuncture at right Waiguan (SJ5)) and sham point group (sham acupuncture). Results of functional magnetic resonance imaging revealed activation in right parietal lobe (Brodmann areas 7 and 19), the right temporal lobe (Brodmann area 39), the right limbic lobe (Brodmann area 23) and bilateral oc-cipital lobes (Brodmann area 18). Furthermore, inhibition of bilateral frontal lobes (Brodmann area 4, 6, and 45), right parietal lobe (Brodmann areas 1 and 5) and left temporal lobe (Brodmann area 21 ) were observed in the true point group. Activation in the precuneus of right parietal lobe (Brodmann area 7) and inhibition of the left superior frontal gyrus (Brodmann area 10) was observed in the sham group. Compared with sham acupuncture, acupuncture at Waiguan in stroke patients inhibited Brodmann area 5 on the healthy side. Results indicated that the altered specificity of sensation-associated cortex (Brodmann area 5) is possibly associated with a central mechanism of acupuncture at Waiguan for stroke patients.展开更多
AIM: To investigate the normal hepatic magnetic resonance spectroscopy findings choline/lipid2 (Cho/Lip2) associated with age and body mass index (BMI).METHODS: A total of 58 single-voxel proton spectra of the liver w...AIM: To investigate the normal hepatic magnetic resonance spectroscopy findings choline/lipid2 (Cho/Lip2) associated with age and body mass index (BMI).METHODS: A total of 58 single-voxel proton spectra of the liver were acquired at 3.0 T using the eightchannel phased array abdominal coil as the receiver coil. Consecutive stacks of breath-hold spectra were acquired using the point resolved spectroscopy technique at a short echo time of 30 ms and a repetition time of 1500 ms. The spectra were processed with the SAGE software package. Areas and heights for metabolite resonance were obtained. Student's t test for unpaired data was used for comparisons of shimming, Cho/Lip2, and lipid content. RESULTS: There were significant negative correlations between the Cho/Lip2 peak height ratios and BMI (r=-0.615) and age (r=-0.398) (all P<0.01). Compared with the high-BMI group, the low-BMI group was younger (39.1±13.0 years vs 47.6±8.5 years, t=-2.954,P=0.005); had better water suppression (93.4%±1.4% vs 85.6%±11.6%, t=2.741, P=0.014); had higher Cho/Lip2 peak heights ratio (0.2±0.14 vs 0.05±0.04,t=6.033,P<0.000); and had lower lipid content (0.03±0.08 vs 0.29±0.31, t=-3.309, P=0.004). Compared with the older group, the younger group had better shimming effects (17.1±3.6 Hz vs 22.0±6.8 Hz, t=-2.919, P=0.008); higher Cho/Lip2 peak heights ratios (0.03±0.05vs 0.09±0.12,t=2.4, P=0.020); and lower lipid content (0.05±0.11 vs 0.23±0.32,t=-2.337,P=0.031). Compared with the lowcholine peak group, the high-choline peak group had lower lipid content (0.005±0.002 vs 0.13±0.23, t=-3.796,P<0.000); lower BMI (19.6±2.4vs 23.9±3.0, t=-4.410, P<0.000); and younger age (34.7±10.0 years vs 43.2±12.5 years, t=-2.088, P=0.041). CONCLUSION: Lipid accumulation could result from the increased fat in the body depending on age and BMI. Lipid can mask the resonance signal of choline.展开更多
Objective Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impact...Objective Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impacts of atmospheric pressure and relative humidity on mortality in Guangzhou, China. Methods This study included 213,737 registered deaths during 2003-2011 in Guangzhou, China. A quasi-Poisson regression with a distributed lag non-linear model was used to assess the effects of atmospheric pressure/relative humidity. Results We found significant effect of low atmospheric pressure/relative humidity on mortality. There was a 1.79% (95% confidence interval: 0.38%-3.22%) increase in non-accidental mortality and a 2.27% (0.07%-4.51%) increase in cardiovascular mortality comparing the 5th and 25th percentile of atmospheric pressure. A 3.97% (0.67%-7.39%) increase in cardiovascular mortality was also observed comparing the 5th and 25th percentile of relative humidity. Women were more vulnerable to decrease in atmospheric pressure and relative humidity than men. Age and education attainment were also potential effect modifiers. Furthermore, low atmospheric pressure and relative humidity increased temperature-related mortality. Conclusion Both low atmospheric pressure and relative humidity are important risk factors of mortality. Our findings would be helpful to develop health risk assessment and climate policy interventions that would better protect vulnerable subgroups of the population.展开更多
The microgravity environment of a long-term space flight may induce acute changes in an astronaut's musculo-skeletal systems. This study explores the effects of simulated microgravity on the mechanical characteristic...The microgravity environment of a long-term space flight may induce acute changes in an astronaut's musculo-skeletal systems. This study explores the effects of simulated microgravity on the mechanical characteristics of articular cartilage. Six rats underwent tail suspension for 14 days and six additional rats were kept under normal earth gravity as controls. Swelling strains were measured using high-frequency ultrasound in all cartilage samples subject to osmotic loading. Site-specific swelling strain data were used in a triphasic theoretical model of cartilage swelling to determine the uniaxial modulus of the cartilage solid matrix. No severe surface irregularities were found in the cartilage samples obtained from the control or tail-suspended groups. For the tail-suspended group, the thickness of the cartilage at a specified site, as determined by ultrasound echo, showed a minor decrease. The uniaxial modulus of articular cartilage at the specified site decreased significantly, from (6.31 ± 3.37) MPa to (5.05 ± 2.98)MPa (p 〈 0.05). The histology- stained image of a cartilage sample also showed a reduced number of chondrocytes and decreased degree of matrix staining. These results demonstrated that the 14 d simulated microgravity induced significant effects on the mechanical characteristics of articular cartilage. This study is the first attempt to explore the effects of simulated microgravity on the mechanical characteristics of articular cartilage using an osmotic loading method and a triphasic model. The conclusions may provide reference information for manned space flights and a better understanding of the effects of microgravity on the skeletal system.展开更多
Mercury sphygmomanometer (MSM) is reliable and widely used in clinics and hospitals. The principle of Korotkoff sounds method (KSM) applied in the MSM is also a gold standard to measure blood pressure. Many efforts ha...Mercury sphygmomanometer (MSM) is reliable and widely used in clinics and hospitals. The principle of Korotkoff sounds method (KSM) applied in the MSM is also a gold standard to measure blood pressure. Many efforts have been made attempting to replace MSM, which is criticized for being not healthy and safe. In this research, an electronic blood pressure monitor, named K-sounds electronic sphygmomanometer (KESM), was designed as a substitute to MSM. The three key elements of KSM were proposed for the first time. We used appropriate electronic components to build the KESM which can fulfill the functions related to the three key elements. The KESM, which was easy to operate and free of mercury, followed the same principle as MSM. The same principle guaranteed the comparable accuracy. We took equivalence test and the results showed that the designed KESM was as accurate as the calibrated standard MSM. The designed KESM passed the certifications of SFDA and is qualified in clinics or hospitals for diagnostic purposes.展开更多
Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform ...Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. The amplitude of sinusoidal motion was set to an amplitude of ±1 cm. The period of the motion was adjustable and set to 3.5 s. Phantom objects of two eggs were placed in a Styrofoam block, which in turn were placed on the motion platform. These objects were used to simulate volumes of interest undergoing ideal periodic motion. CT data of static phantom were acquired using a multi-slice general electric (GE) LightSpeed 16-slice CT scanner in an axial mode. And the CT data of periodical motion phantom were acquired in an axial and cine-mode scan. A software program was developed by using VC++ and VTK software tools to resort the CT data and reconstruct the 4D-CT. Then all of the CT data with same phase were sorted by the program into the same series based on the similarity principle of spatial adjacent images and mutual information measure among them, and 3D reconstruction of different phase CT data were completed by using the software. Results:All of the CT data were sorted accurately into different series based on the similarity principle of spatial adjacent images and mutual information measures among them. Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced significantly, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusion:Time-resolved 4D-CT reconstruction can be implemented with any general multi-slice CT scanners based on the similarity principle of spatial adjacent images and mutual information measure.The process of the 4D-CT data acquisition and reconstruction were not restricted to the hardware or software of the CT scanner and has the feasibility ,which extensive applicability.展开更多
Objective:To investigate the influences of motion artifacts on three-dimensional (3D) reconstruction volume and conformal radiotherapy planning. Methods:A phantom which can mimic the clip motion of lung tumor along th...Objective:To investigate the influences of motion artifacts on three-dimensional (3D) reconstruction volume and conformal radiotherapy planning. Methods:A phantom which can mimic the clip motion of lung tumor along the cranial-caudal direction is constructed by step motor, small ball of polyethylene and potato. Ten different scan protocols were set and CT data of the phantom were acquired by using a commercial GE LightSpeed16 CT scanner. The 3D reconstruction of the CT data was implemented by adopting volume-rendering technology of GE AdvantageSim 6.0 system. The reconstructed volumes of each target in different scan protocols were measured through 3D measuring tools. Thus, relative deviations of the reconstruction volumes between moving targets and static ones were determined. The three-dimensional conformal radiation therapy (3D-CRT) plans and conformal fields were created and compared for a static/moving target with the WiMRT treatment planning system (TPS). Results:For a static target, there was no obvious difference among the 3D reconstruction volumes when the CT data were acquired with different pitches and slices. The appearance of 3D reconstruction volume and 3D conformal field of a moving target was quite different from that of static one. The maximum relative deviation is nearly 90% for a moving target scanned with different scan protocols. The relative deviations are variable among the different targets, about from -39.8% to 89.5% for a smaller target and from -18.4% to 20.5% for a larger one. Conclusion:The motion artifacts have great effects on 3D-CRT planning and reconstruction volume, which will greatly induce distorted conformal radiation fields and false DVHs for a moving target.展开更多
In this paper, a new approach of multimodality image registration is represented with not only image intensity, but also features describing image structure. There are two novelties in the proposed method. Firstly, in...In this paper, a new approach of multimodality image registration is represented with not only image intensity, but also features describing image structure. There are two novelties in the proposed method. Firstly, instead of standard mutual information ( MI ) based on joint intensity histogram, regional mutual information ( RMI ) is employed, which allows neighborhood information to be taken into account. Secondly, a new feature images obtained by means of phase congruency are invariants to brightness or contrast changes. By incorporating these features and intensity into RMI, we can combine the aspects of both structural and neighborhood information together, which offers a more robust and a high level of registration accuracy.展开更多
Objective: Neurons in the cochlear nucleus show different response patterns to the short tone bursts. Because of the limitations of animal experiments, it is hard to explore the principle. Therefore, using a model to ...Objective: Neurons in the cochlear nucleus show different response patterns to the short tone bursts. Because of the limitations of animal experiments, it is hard to explore the principle. Therefore, using a model to simulate CN neurons will be a feasible way. Methods: Based on the initial model mentioned in the previous study, we proposed an improved CN model in MATLAB R2012b. Results: By modifying the parameters of the model we found the interchanges among "primary-like", "chopper",and "onset" response patterns. Furthermore, we simulated the "pauser" response pattern by adding an extra input in our model. Conclusion: The results indicate that the synaptic integrations and the input modes can give rise to different characteristics of CN neurons, which eventually determine the response patterns of CN neurons.展开更多
The C-C method was adopted to analyze the nonlinear characteristics of masseter electromyography (EMG) signals and the chaotic degree by the largest Lyapunov exponent (LLE) of different genders and sides.First,the emb...The C-C method was adopted to analyze the nonlinear characteristics of masseter electromyography (EMG) signals and the chaotic degree by the largest Lyapunov exponent (LLE) of different genders and sides.First,the embedding dimension and the delay time were obtained through this method,then the phase space was reconstructed to resume the chaotic attractor and determine the LLE.The result shows that the trajectory of attractor is denser than Chen's attractor,and the LLE is positive,which means that not only the signal has the character of chaos,but also the chaotic degree of masseter EMG is relatively high.According to the value of the LLE,the chaotic degree of men's masseter EMG is higher than that of women's;when the dentition is normal,the chaotic degree of two sides is almost the same.Then,a conclusion can be deduced that if the LLE of both sides are in great difference,the unilateral mastication is likely to exist,which means that the nonlinear characteristics of masseter EMG can be applied to predict the unilateral mastication.展开更多
In this paper, we study the Beurling-Ahlfors extensions and prove two results. The first variation of the Beurling-Ahlfors extension is not always harmonic; the Beurling-Ahlfors extension of a quasisymmetric mapping i...In this paper, we study the Beurling-Ahlfors extensions and prove two results. The first variation of the Beurling-Ahlfors extension is not always harmonic; the Beurling-Ahlfors extension of a quasisymmetric mapping is not always harmonic.展开更多
Functional near-infrared spectroscopy(fNIRS),as a new optical functional neuroimaging method,has been widely used in neuroscience research.In some research fields with NIRS,heartrate(HR)(or heartbeat)is needed as usef...Functional near-infrared spectroscopy(fNIRS),as a new optical functional neuroimaging method,has been widely used in neuroscience research.In some research fields with NIRS,heartrate(HR)(or heartbeat)is needed as useful information to evaluate its influence,or to know the state ofsubject,or to remove its artifact.If HR(or heartbeat)can be detected with high accuracy from theoptical intensity,this will undoubtedly benefit a lot to many NIRS studies.Previous studies haveused the moving time window method or mathematical morphology method(MMM)to detectheartbeats in the optical intensity.However,there are some disadvantages in these methods.In thisstudy,we proposed a method combining the periodic information of heartbeats and the operator ofmathematical morphology to automatically detect heartbeats in the optical intensity.First theoptical intensity is smoothed using a moving average flter.Then,the opening operator of math-ematical morphology extracts peaks in the smoothed optical intensity.Finally,one peak is iden-tified as a heartbeat peak if this peak is the maximum in a predefined point range.Throughvalidation on experimental data,our method can overcome the disadvantages of previous methods,and detet heartbeats in the optical signal of fNIRS with nearly 100%accuracy.展开更多
Photodynamic therapy(PDT)is applied as a robust therapeutic option for tumor,which exhibits some advantages of unique selectivity and irreversible damage to tumor cells.Among which,photosensitizer(PS),appropriate lase...Photodynamic therapy(PDT)is applied as a robust therapeutic option for tumor,which exhibits some advantages of unique selectivity and irreversible damage to tumor cells.Among which,photosensitizer(PS),appropriate laser irradiation and oxygen(O_(2))are three essential components for PDT,but the hypoxic tumor microenvironment(TME)restricts the O_(2) supply in tumor tissues.Even worse,tumor metastasis and drug resistance frequently happen under hypoxic condition,which further deteriorate the antitumor effect of PDT.To enhance the PDT efficiency,critical attention has been received by relieving tumor hypoxia,and innovative strategies on this topic continue to emerge.Traditionally,the O_(2) supplement strategy is considered as a direct and effective strategy to relieve TME,whereas it is confronted with great challenges for continuous O_(2) supply.Recently,O_(2)-independent PDT provides a brand new strategy to enhance the antitumor efficiency,which can avoid the influence of TME.In addition,PDT can synergize with other antitumor strategies,such as chemotherapy,immunotherapy,photothermal therapy(PTT)and starvation therapy,to remedy the inadequate PDT effect under hypoxia conditions.In this paper,we summarized the latest progresses in the development of innovative strategies to improve PDT efficacy against hypoxic tumor,which were classified into O_(2)-dependent PDT,O_(2)-independent PDT and synergistic therapy.Furthermore,the advantages and deficiencies of various strategies were also discussed to envisage the prospects and challenges in future study.展开更多
Sea squirt,as a highly invasive species and main biofouling source in marine aquaculture,has seriously threatened the biodiversity and aquaculture economy.On the other hand,a conductive biomaterial with excellent bioc...Sea squirt,as a highly invasive species and main biofouling source in marine aquaculture,has seriously threatened the biodiversity and aquaculture economy.On the other hand,a conductive biomaterial with excellent biocompatibility,and appropriate mechanical property from renewable resources is urgently required for tissue engineering patches.To meet these targets,we presented a novel and robust strategy for sustainable development aiming at the marine pollution via recycling and upgrading the waste biomass-sea squirts and serving as a renewable resource for functional bio-scaffold patch in tissue engineering.We firstly demonstrated that the tunic cellulose derived natural self-conductive scaffolds successfully served as functional cardiac patches,which significantly promote the maturation and spontaneous contraction of cardiomyocytes both in vitro and enhance cardiac function of MI rats in vivo.We believe this novel,feasible and“Trash to Treasure”strategy to gain cardiac patches via recycling the waste biomass must be promising and beneficial for marine environmental bio-pollution issue and sustainable development considering the large-scale consumption potential for tissue engineering and other applications.展开更多
At present,dental implant surgery mainly relies on the clinical experience of the doctor and the assistance of preoperative medical imaging.However,there are some problems in dental implant surgery,such as narrow spac...At present,dental implant surgery mainly relies on the clinical experience of the doctor and the assistance of preoperative medical imaging.However,there are some problems in dental implant surgery,such as narrow space,sight obstruction,inaccurate positioning,and high requirements of doctors’proficiency.Therefore,a dental implant robot system(DIRS)guided by optical navigation is developed in this study,with an x-shaped tool and an irregular pentagonal tracer are designed for spatial registration and needle tip positioning strategy respectively.The coordinate system of each unit in DIRS is unified through system calibration,spatial registration,and needle tip positioning strategy.Then the surgical path is planned on the computed tomography(CT)images in the navigation software before operation.The automatic positioning method and the auxiliary positioning method can be used in the operation to achieve accurate positioning and assist doctors to complete the operation.The errors of spatial registration,needle tip positioning strategy,and the overall accuracy of the system were evaluated respectively,and the results showed that they all met the needs of clinical surgery.This study preliminarily verified the feasibility of the precise positioning method for dental surgery robots and provided certain ideas for subsequent related research.展开更多
A key step of constructing active appearance model is requiring a set of appropriate training shapes with well-defined correspondences.In this paper,we introduce a novel point correspondence method(FB-CPD),which can i...A key step of constructing active appearance model is requiring a set of appropriate training shapes with well-defined correspondences.In this paper,we introduce a novel point correspondence method(FB-CPD),which can improve the accuracy of coherent point drift(CPD) by using the information of image feature.The objective function of the proposed method is defined by both of geometric spatial information and image feature information,and the origin Gaussian mixture model in CPD is modified according to the image feature of points.FB-CPD is tested on the 3D prostate and liver point sets through the simulation experiments.The registration error can be reduced efficiently by FB-CPD.Moreover,the active appearance model constructed by FB-CPD can obtain fine segmentation in 3D CT prostate image.Compared with the original CPD,the overlap ratio of voxels was improved from 88.7% to 90.2% by FB-CPD.展开更多
To the Editor:Adipose tissue occurs in at least two different entities in mammals and humans:brown adipose tissue(BAT)and white adipose tissue(WAT).BAT is characterized by a unique uncoupling protein 1(UCP1)in the mit...To the Editor:Adipose tissue occurs in at least two different entities in mammals and humans:brown adipose tissue(BAT)and white adipose tissue(WAT).BAT is characterized by a unique uncoupling protein 1(UCP1)in the mitochondria that enables the uncoupling of the respiratory chain from adenosine triphosphate synthesis.Thus,energy is dissipated as heat to reduce fat accumulation.BAT is also considered a highly heterogeneous tissue with abundant oxygen,blood supply,and iron-rich mitochondria.[1,2]Activation of BAT via exposure to a cold environment is considered to be a means of reducing triglycerides to fight obesity.[3]The alterations in cells and tissues of activated BAT include increased iron content and UCP1 expression in mitochondrial,blood perfusion,and lipid utilization.[4]Therefore,accurate identification and quantitative analysis of inactive and activated BAT are of great significance for the treatment of metabolic diseases that target BAT,such as obesity.展开更多
Background: The zone of calcified cartilage (ZCC) plays an important role in the pathogenesis of osteoarthritis (OA) but has never been imaged in vivo with magnetic resonance (MR) imaging techniques. We investigated t...Background: The zone of calcified cartilage (ZCC) plays an important role in the pathogenesis of osteoarthritis (OA) but has never been imaged in vivo with magnetic resonance (MR) imaging techniques. We investigated the feasibility of direct imaging of the ZCC in both cadaveric whole knee specimens and in vivo healthy knees using a 3-dimensional ultrashort echo time cones (3D UTE-Cones) sequence on a clinical 3T scanner. Methods: In all, 12 cadaveric knee joints and 10 in vivo healthy were collected. At a 3T MR scanner with an 8-channel knee coil, a fat-saturated 3D dual-echo UTE-Cones sequence was used to image the ZCC, following with a short rectangular pulse excitation and 3D spiral sampling with conical view ordering. The regions of interests (ROIs) were delineated by a blinded observer. Singlecomponent T2* and T2 values were calculated from fat-saturated 3D dual-echo UTE-Cones and a Carr-Purcell-Meiboom-Gill (T2 CPMG) data using a semi-automated MATLAB code. Results: The single-exponential fitting curve of ZCC was accurately obtained with R2 of 0.989. For keen joint samples, the ZCC has a short T2* ranging from 0.62 to 2.55 ms, with the mean ±standard deviation (SD) of 1.49 ±0.66 ms, and with 95% confidence intervals (CI) of 1.20-1.78 ms. For volunteers, the short T2* ranges from 0.93 to 3.52ms, with the mean±SD of 2.09±0.56 ms, and the 95% CI is 1.43 to 2.74ms in ZCC. Conclusions: The high-resolution 3D UTE-Cones sequence might be used to directly image ZCC in the human knee joint on a clinical 3T scanner with a scan time of more than 10 min. Using this non-invasive technique, the T2* relaxation time of the ZCC can be further detected.展开更多
The purpose of this study was to explore the triphasic mechanical properties of osteoarthritic cartilage with different pathological grades.First,samples of cartilage from rabbits with different stages of osteoarthrit...The purpose of this study was to explore the triphasic mechanical properties of osteoarthritic cartilage with different pathological grades.First,samples of cartilage from rabbits with different stages of osteoarthritis (OA) were graded.Following this,the cartilage was strained by a swelling experiment,and changes were measured using a high-frequency ultrasound system.The result,together with fixed charge density and water volume fraction of cartilage samples,was used to estimate the uniaxial modulus of the cartilage tissue,based on a triphasic model.For the control cartilage samples,the uniaxial elastic modulus on the cartilage surface was lower than those in the middle and deep layers.With an increase in the OA grade,the uniaxial elastic modulus of the surface,middle and deep layers decreased.A significant difference was found in the surface elastic modulus of different OA grades (P<0.01),while no significant differences were identified for OA cartilages of Grades 1 and 2 in the middle and deep layers (P<0.01).Compared with Grades 1 and 2,there was a significant reduction in the elastic modulus in the middle and deep layers of Grade 3 OA cartilage (P<0.05).Overall,this study may provide a new quantitative method to evaluate the severity of OA using the mechanical properties of cartilage tissue.展开更多
For the segmentation of X-ray angiograms (XRA), the essential feature and the prior knowledge of angiographic image were analyzed, and a multi-feature based fuzzy recognition (MFFR) algorithm was proposed to infer...For the segmentation of X-ray angiograms (XRA), the essential feature and the prior knowledge of angiographic image were analyzed, and a multi-feature based fuzzy recognition (MFFR) algorithm was proposed to infer the local vessel structure in this paper. Guided by the prior knowledge of artery vessel, a probability tracking operator (PTO) can rapidly track along the artery tree, and walk across the weak region or gaps because of disturbance or preprocessing to angiographic image. Another, the accurate measurement of the vascular axis-lines and diameters can be synchronously implemented in the tracking process. To correctly evaluate the proposed method, a simulated image of CAT and some clinical XRA images were used in the experimentations. The algorithms performed better than the conventional one: given one start-point, on average 92.7% of the visible segments or branches was automatically delineated; the correctness ratio of vessel structure inference reached to 90.0% on the average.展开更多
基金the State Plan for Development of Basic Research in Key Areas(973 Program)in China,No.2006CB504505,2012CB518504the Key Subject Construction Project of"211 Engineering"III Stage of Guangdong Province in Chinathe Guangdong Provincial"College Students’Innovative Experiment Plan"Project in China,No.1212112038
文摘Most studies addressing the specificity of meridians and acupuncture points have focused mainly on the different neural effects of acupuncture at different points in healthy individuals. This study examined the effects of acupuncture on brain function in a pathological context. Sixteen patients with ischemic stroke were randomly assigned to true point group (true acupuncture at right Waiguan (SJ5)) and sham point group (sham acupuncture). Results of functional magnetic resonance imaging revealed activation in right parietal lobe (Brodmann areas 7 and 19), the right temporal lobe (Brodmann area 39), the right limbic lobe (Brodmann area 23) and bilateral oc-cipital lobes (Brodmann area 18). Furthermore, inhibition of bilateral frontal lobes (Brodmann area 4, 6, and 45), right parietal lobe (Brodmann areas 1 and 5) and left temporal lobe (Brodmann area 21 ) were observed in the true point group. Activation in the precuneus of right parietal lobe (Brodmann area 7) and inhibition of the left superior frontal gyrus (Brodmann area 10) was observed in the sham group. Compared with sham acupuncture, acupuncture at Waiguan in stroke patients inhibited Brodmann area 5 on the healthy side. Results indicated that the altered specificity of sensation-associated cortex (Brodmann area 5) is possibly associated with a central mechanism of acupuncture at Waiguan for stroke patients.
基金Supported by The Science Foundation of Guangdong Province for Dr. Startup Project, No. S2012040006618Postdoctoral Fund of Guangzhou University of Traditional Chinese Medicine,No. 20120621+2 种基金Traditional Chinese Medicine and Integration of Traditional Chinese and Western Medicine Research Project of Guangzhou, No. 20122A011032The National Natural Science Foundation of China, No. 30700184, 61172034, 81271654,81271569 and 81171329Science and Technology Planning Project of Guangdong Province, China, No. 2008B080703041,2010B080701025 and 2011B031700014
文摘AIM: To investigate the normal hepatic magnetic resonance spectroscopy findings choline/lipid2 (Cho/Lip2) associated with age and body mass index (BMI).METHODS: A total of 58 single-voxel proton spectra of the liver were acquired at 3.0 T using the eightchannel phased array abdominal coil as the receiver coil. Consecutive stacks of breath-hold spectra were acquired using the point resolved spectroscopy technique at a short echo time of 30 ms and a repetition time of 1500 ms. The spectra were processed with the SAGE software package. Areas and heights for metabolite resonance were obtained. Student's t test for unpaired data was used for comparisons of shimming, Cho/Lip2, and lipid content. RESULTS: There were significant negative correlations between the Cho/Lip2 peak height ratios and BMI (r=-0.615) and age (r=-0.398) (all P<0.01). Compared with the high-BMI group, the low-BMI group was younger (39.1±13.0 years vs 47.6±8.5 years, t=-2.954,P=0.005); had better water suppression (93.4%±1.4% vs 85.6%±11.6%, t=2.741, P=0.014); had higher Cho/Lip2 peak heights ratio (0.2±0.14 vs 0.05±0.04,t=6.033,P<0.000); and had lower lipid content (0.03±0.08 vs 0.29±0.31, t=-3.309, P=0.004). Compared with the older group, the younger group had better shimming effects (17.1±3.6 Hz vs 22.0±6.8 Hz, t=-2.919, P=0.008); higher Cho/Lip2 peak heights ratios (0.03±0.05vs 0.09±0.12,t=2.4, P=0.020); and lower lipid content (0.05±0.11 vs 0.23±0.32,t=-2.337,P=0.031). Compared with the lowcholine peak group, the high-choline peak group had lower lipid content (0.005±0.002 vs 0.13±0.23, t=-3.796,P<0.000); lower BMI (19.6±2.4vs 23.9±3.0, t=-4.410, P<0.000); and younger age (34.7±10.0 years vs 43.2±12.5 years, t=-2.088, P=0.041). CONCLUSION: Lipid accumulation could result from the increased fat in the body depending on age and BMI. Lipid can mask the resonance signal of choline.
基金funded by National Nature Science Foundation of China[81102207]Science and Technology Planning Project of Guangdong Province,China[2013B021800041]GUO Yu Ming is supported by NHMRC Centre for air quality and health research and evaluation,Australia[APP 1030259]
文摘Objective Although many studies have examined the effects of ambient temperatures on mortality, little evidence is on health impacts of atmospheric pressure and relative humidity. This study aimed to assess the impacts of atmospheric pressure and relative humidity on mortality in Guangzhou, China. Methods This study included 213,737 registered deaths during 2003-2011 in Guangzhou, China. A quasi-Poisson regression with a distributed lag non-linear model was used to assess the effects of atmospheric pressure/relative humidity. Results We found significant effect of low atmospheric pressure/relative humidity on mortality. There was a 1.79% (95% confidence interval: 0.38%-3.22%) increase in non-accidental mortality and a 2.27% (0.07%-4.51%) increase in cardiovascular mortality comparing the 5th and 25th percentile of atmospheric pressure. A 3.97% (0.67%-7.39%) increase in cardiovascular mortality was also observed comparing the 5th and 25th percentile of relative humidity. Women were more vulnerable to decrease in atmospheric pressure and relative humidity than men. Age and education attainment were also potential effect modifiers. Furthermore, low atmospheric pressure and relative humidity increased temperature-related mortality. Conclusion Both low atmospheric pressure and relative humidity are important risk factors of mortality. Our findings would be helpful to develop health risk assessment and climate policy interventions that would better protect vulnerable subgroups of the population.
基金supported by the National Natural Science Foundation of China (31170896)State Key Laboratory of Software Development Environment (SKLSDE-2011ZX-11)
文摘The microgravity environment of a long-term space flight may induce acute changes in an astronaut's musculo-skeletal systems. This study explores the effects of simulated microgravity on the mechanical characteristics of articular cartilage. Six rats underwent tail suspension for 14 days and six additional rats were kept under normal earth gravity as controls. Swelling strains were measured using high-frequency ultrasound in all cartilage samples subject to osmotic loading. Site-specific swelling strain data were used in a triphasic theoretical model of cartilage swelling to determine the uniaxial modulus of the cartilage solid matrix. No severe surface irregularities were found in the cartilage samples obtained from the control or tail-suspended groups. For the tail-suspended group, the thickness of the cartilage at a specified site, as determined by ultrasound echo, showed a minor decrease. The uniaxial modulus of articular cartilage at the specified site decreased significantly, from (6.31 ± 3.37) MPa to (5.05 ± 2.98)MPa (p 〈 0.05). The histology- stained image of a cartilage sample also showed a reduced number of chondrocytes and decreased degree of matrix staining. These results demonstrated that the 14 d simulated microgravity induced significant effects on the mechanical characteristics of articular cartilage. This study is the first attempt to explore the effects of simulated microgravity on the mechanical characteristics of articular cartilage using an osmotic loading method and a triphasic model. The conclusions may provide reference information for manned space flights and a better understanding of the effects of microgravity on the skeletal system.
基金Supported by the Innovation Fund Project from Ministry of Science and Technology of China (08C26214401239)
文摘Mercury sphygmomanometer (MSM) is reliable and widely used in clinics and hospitals. The principle of Korotkoff sounds method (KSM) applied in the MSM is also a gold standard to measure blood pressure. Many efforts have been made attempting to replace MSM, which is criticized for being not healthy and safe. In this research, an electronic blood pressure monitor, named K-sounds electronic sphygmomanometer (KESM), was designed as a substitute to MSM. The three key elements of KSM were proposed for the first time. We used appropriate electronic components to build the KESM which can fulfill the functions related to the three key elements. The KESM, which was easy to operate and free of mercury, followed the same principle as MSM. The same principle guaranteed the comparable accuracy. We took equivalence test and the results showed that the designed KESM was as accurate as the calibrated standard MSM. The designed KESM passed the certifications of SFDA and is qualified in clinics or hospitals for diagnostic purposes.
基金Guangzhou Municipal Medicine &Health ProgramGrant number:2006-YB-177+1 种基金Guangdong Province Medicine Scientific Research ProgramGrant number:A2007290
文摘Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. The amplitude of sinusoidal motion was set to an amplitude of ±1 cm. The period of the motion was adjustable and set to 3.5 s. Phantom objects of two eggs were placed in a Styrofoam block, which in turn were placed on the motion platform. These objects were used to simulate volumes of interest undergoing ideal periodic motion. CT data of static phantom were acquired using a multi-slice general electric (GE) LightSpeed 16-slice CT scanner in an axial mode. And the CT data of periodical motion phantom were acquired in an axial and cine-mode scan. A software program was developed by using VC++ and VTK software tools to resort the CT data and reconstruct the 4D-CT. Then all of the CT data with same phase were sorted by the program into the same series based on the similarity principle of spatial adjacent images and mutual information measure among them, and 3D reconstruction of different phase CT data were completed by using the software. Results:All of the CT data were sorted accurately into different series based on the similarity principle of spatial adjacent images and mutual information measures among them. Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced significantly, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusion:Time-resolved 4D-CT reconstruction can be implemented with any general multi-slice CT scanners based on the similarity principle of spatial adjacent images and mutual information measure.The process of the 4D-CT data acquisition and reconstruction were not restricted to the hardware or software of the CT scanner and has the feasibility ,which extensive applicability.
基金Grant sponsor:Guangzhou Municipal Medicin &Health ProgramGrant number:2006-YB-177
文摘Objective:To investigate the influences of motion artifacts on three-dimensional (3D) reconstruction volume and conformal radiotherapy planning. Methods:A phantom which can mimic the clip motion of lung tumor along the cranial-caudal direction is constructed by step motor, small ball of polyethylene and potato. Ten different scan protocols were set and CT data of the phantom were acquired by using a commercial GE LightSpeed16 CT scanner. The 3D reconstruction of the CT data was implemented by adopting volume-rendering technology of GE AdvantageSim 6.0 system. The reconstructed volumes of each target in different scan protocols were measured through 3D measuring tools. Thus, relative deviations of the reconstruction volumes between moving targets and static ones were determined. The three-dimensional conformal radiation therapy (3D-CRT) plans and conformal fields were created and compared for a static/moving target with the WiMRT treatment planning system (TPS). Results:For a static target, there was no obvious difference among the 3D reconstruction volumes when the CT data were acquired with different pitches and slices. The appearance of 3D reconstruction volume and 3D conformal field of a moving target was quite different from that of static one. The maximum relative deviation is nearly 90% for a moving target scanned with different scan protocols. The relative deviations are variable among the different targets, about from -39.8% to 89.5% for a smaller target and from -18.4% to 20.5% for a larger one. Conclusion:The motion artifacts have great effects on 3D-CRT planning and reconstruction volume, which will greatly induce distorted conformal radiation fields and false DVHs for a moving target.
文摘In this paper, a new approach of multimodality image registration is represented with not only image intensity, but also features describing image structure. There are two novelties in the proposed method. Firstly, instead of standard mutual information ( MI ) based on joint intensity histogram, regional mutual information ( RMI ) is employed, which allows neighborhood information to be taken into account. Secondly, a new feature images obtained by means of phase congruency are invariants to brightness or contrast changes. By incorporating these features and intensity into RMI, we can combine the aspects of both structural and neighborhood information together, which offers a more robust and a high level of registration accuracy.
基金National Natural Science Foundation of Chinagrant number:31171059
文摘Objective: Neurons in the cochlear nucleus show different response patterns to the short tone bursts. Because of the limitations of animal experiments, it is hard to explore the principle. Therefore, using a model to simulate CN neurons will be a feasible way. Methods: Based on the initial model mentioned in the previous study, we proposed an improved CN model in MATLAB R2012b. Results: By modifying the parameters of the model we found the interchanges among "primary-like", "chopper",and "onset" response patterns. Furthermore, we simulated the "pauser" response pattern by adding an extra input in our model. Conclusion: The results indicate that the synaptic integrations and the input modes can give rise to different characteristics of CN neurons, which eventually determine the response patterns of CN neurons.
文摘The C-C method was adopted to analyze the nonlinear characteristics of masseter electromyography (EMG) signals and the chaotic degree by the largest Lyapunov exponent (LLE) of different genders and sides.First,the embedding dimension and the delay time were obtained through this method,then the phase space was reconstructed to resume the chaotic attractor and determine the LLE.The result shows that the trajectory of attractor is denser than Chen's attractor,and the LLE is positive,which means that not only the signal has the character of chaos,but also the chaotic degree of masseter EMG is relatively high.According to the value of the LLE,the chaotic degree of men's masseter EMG is higher than that of women's;when the dentition is normal,the chaotic degree of two sides is almost the same.Then,a conclusion can be deduced that if the LLE of both sides are in great difference,the unilateral mastication is likely to exist,which means that the nonlinear characteristics of masseter EMG can be applied to predict the unilateral mastication.
基金The NSF (11101290) for Young Scientists of China,the NSF (11071179,10871211) of ChinaScientific Research Starting Foundation (00035242) of Shenzhen University
文摘In this paper, we study the Beurling-Ahlfors extensions and prove two results. The first variation of the Beurling-Ahlfors extension is not always harmonic; the Beurling-Ahlfors extension of a quasisymmetric mapping is not always harmonic.
基金support from the PhD research startup foundation of Guangdong Medical University(2XB14006).
文摘Functional near-infrared spectroscopy(fNIRS),as a new optical functional neuroimaging method,has been widely used in neuroscience research.In some research fields with NIRS,heartrate(HR)(or heartbeat)is needed as useful information to evaluate its influence,or to know the state ofsubject,or to remove its artifact.If HR(or heartbeat)can be detected with high accuracy from theoptical intensity,this will undoubtedly benefit a lot to many NIRS studies.Previous studies haveused the moving time window method or mathematical morphology method(MMM)to detectheartbeats in the optical intensity.However,there are some disadvantages in these methods.In thisstudy,we proposed a method combining the periodic information of heartbeats and the operator ofmathematical morphology to automatically detect heartbeats in the optical intensity.First theoptical intensity is smoothed using a moving average flter.Then,the opening operator of math-ematical morphology extracts peaks in the smoothed optical intensity.Finally,one peak is iden-tified as a heartbeat peak if this peak is the maximum in a predefined point range.Throughvalidation on experimental data,our method can overcome the disadvantages of previous methods,and detet heartbeats in the optical signal of fNIRS with nearly 100%accuracy.
文摘Photodynamic therapy(PDT)is applied as a robust therapeutic option for tumor,which exhibits some advantages of unique selectivity and irreversible damage to tumor cells.Among which,photosensitizer(PS),appropriate laser irradiation and oxygen(O_(2))are three essential components for PDT,but the hypoxic tumor microenvironment(TME)restricts the O_(2) supply in tumor tissues.Even worse,tumor metastasis and drug resistance frequently happen under hypoxic condition,which further deteriorate the antitumor effect of PDT.To enhance the PDT efficiency,critical attention has been received by relieving tumor hypoxia,and innovative strategies on this topic continue to emerge.Traditionally,the O_(2) supplement strategy is considered as a direct and effective strategy to relieve TME,whereas it is confronted with great challenges for continuous O_(2) supply.Recently,O_(2)-independent PDT provides a brand new strategy to enhance the antitumor efficiency,which can avoid the influence of TME.In addition,PDT can synergize with other antitumor strategies,such as chemotherapy,immunotherapy,photothermal therapy(PTT)and starvation therapy,to remedy the inadequate PDT effect under hypoxia conditions.In this paper,we summarized the latest progresses in the development of innovative strategies to improve PDT efficacy against hypoxic tumor,which were classified into O_(2)-dependent PDT,O_(2)-independent PDT and synergistic therapy.Furthermore,the advantages and deficiencies of various strategies were also discussed to envisage the prospects and challenges in future study.
基金This work was supported by the National Natural Science Foundation of China(32071363,52003113,U1601221)Science and Technology Projects of Guangzhou City(201804020035)+1 种基金Guangdong Province Science and Technology Projects(2016B090913004)Key Research&Development Program of Guangzhou Regenerative Medicine and Health Guangdong Laboratory(2018GZR110104002).
文摘Sea squirt,as a highly invasive species and main biofouling source in marine aquaculture,has seriously threatened the biodiversity and aquaculture economy.On the other hand,a conductive biomaterial with excellent biocompatibility,and appropriate mechanical property from renewable resources is urgently required for tissue engineering patches.To meet these targets,we presented a novel and robust strategy for sustainable development aiming at the marine pollution via recycling and upgrading the waste biomass-sea squirts and serving as a renewable resource for functional bio-scaffold patch in tissue engineering.We firstly demonstrated that the tunic cellulose derived natural self-conductive scaffolds successfully served as functional cardiac patches,which significantly promote the maturation and spontaneous contraction of cardiomyocytes both in vitro and enhance cardiac function of MI rats in vivo.We believe this novel,feasible and“Trash to Treasure”strategy to gain cardiac patches via recycling the waste biomass must be promising and beneficial for marine environmental bio-pollution issue and sustainable development considering the large-scale consumption potential for tissue engineering and other applications.
基金Natural Science Foundation of Guangdong Province(Grant No.2021A1515011208)National Natural Scientific Foundation of China(Grant No.81671788)+1 种基金National Science Foundation for Young Scientists of China(Grant No.81701662)The Joint Found of National Science Foundation of China and GuangDong Provincial Government(Grant No.U1301258).
文摘At present,dental implant surgery mainly relies on the clinical experience of the doctor and the assistance of preoperative medical imaging.However,there are some problems in dental implant surgery,such as narrow space,sight obstruction,inaccurate positioning,and high requirements of doctors’proficiency.Therefore,a dental implant robot system(DIRS)guided by optical navigation is developed in this study,with an x-shaped tool and an irregular pentagonal tracer are designed for spatial registration and needle tip positioning strategy respectively.The coordinate system of each unit in DIRS is unified through system calibration,spatial registration,and needle tip positioning strategy.Then the surgical path is planned on the computed tomography(CT)images in the navigation software before operation.The automatic positioning method and the auxiliary positioning method can be used in the operation to achieve accurate positioning and assist doctors to complete the operation.The errors of spatial registration,needle tip positioning strategy,and the overall accuracy of the system were evaluated respectively,and the results showed that they all met the needs of clinical surgery.This study preliminarily verified the feasibility of the precise positioning method for dental surgery robots and provided certain ideas for subsequent related research.
基金National Basic Research Program of China(973 Program)grant number:2010CB732505+1 种基金National Natural Science Foundation of Chinagrant number:30900380
文摘A key step of constructing active appearance model is requiring a set of appropriate training shapes with well-defined correspondences.In this paper,we introduce a novel point correspondence method(FB-CPD),which can improve the accuracy of coherent point drift(CPD) by using the information of image feature.The objective function of the proposed method is defined by both of geometric spatial information and image feature information,and the origin Gaussian mixture model in CPD is modified according to the image feature of points.FB-CPD is tested on the 3D prostate and liver point sets through the simulation experiments.The registration error can be reduced efficiently by FB-CPD.Moreover,the active appearance model constructed by FB-CPD can obtain fine segmentation in 3D CT prostate image.Compared with the original CPD,the overlap ratio of voxels was improved from 88.7% to 90.2% by FB-CPD.
基金National Natural Science Foundation of China(No.81801653)
文摘To the Editor:Adipose tissue occurs in at least two different entities in mammals and humans:brown adipose tissue(BAT)and white adipose tissue(WAT).BAT is characterized by a unique uncoupling protein 1(UCP1)in the mitochondria that enables the uncoupling of the respiratory chain from adenosine triphosphate synthesis.Thus,energy is dissipated as heat to reduce fat accumulation.BAT is also considered a highly heterogeneous tissue with abundant oxygen,blood supply,and iron-rich mitochondria.[1,2]Activation of BAT via exposure to a cold environment is considered to be a means of reducing triglycerides to fight obesity.[3]The alterations in cells and tissues of activated BAT include increased iron content and UCP1 expression in mitochondrial,blood perfusion,and lipid utilization.[4]Therefore,accurate identification and quantitative analysis of inactive and activated BAT are of great significance for the treatment of metabolic diseases that target BAT,such as obesity.
文摘Background: The zone of calcified cartilage (ZCC) plays an important role in the pathogenesis of osteoarthritis (OA) but has never been imaged in vivo with magnetic resonance (MR) imaging techniques. We investigated the feasibility of direct imaging of the ZCC in both cadaveric whole knee specimens and in vivo healthy knees using a 3-dimensional ultrashort echo time cones (3D UTE-Cones) sequence on a clinical 3T scanner. Methods: In all, 12 cadaveric knee joints and 10 in vivo healthy were collected. At a 3T MR scanner with an 8-channel knee coil, a fat-saturated 3D dual-echo UTE-Cones sequence was used to image the ZCC, following with a short rectangular pulse excitation and 3D spiral sampling with conical view ordering. The regions of interests (ROIs) were delineated by a blinded observer. Singlecomponent T2* and T2 values were calculated from fat-saturated 3D dual-echo UTE-Cones and a Carr-Purcell-Meiboom-Gill (T2 CPMG) data using a semi-automated MATLAB code. Results: The single-exponential fitting curve of ZCC was accurately obtained with R2 of 0.989. For keen joint samples, the ZCC has a short T2* ranging from 0.62 to 2.55 ms, with the mean ±standard deviation (SD) of 1.49 ±0.66 ms, and with 95% confidence intervals (CI) of 1.20-1.78 ms. For volunteers, the short T2* ranges from 0.93 to 3.52ms, with the mean±SD of 2.09±0.56 ms, and the 95% CI is 1.43 to 2.74ms in ZCC. Conclusions: The high-resolution 3D UTE-Cones sequence might be used to directly image ZCC in the human knee joint on a clinical 3T scanner with a scan time of more than 10 min. Using this non-invasive technique, the T2* relaxation time of the ZCC can be further detected.
基金supported by the National Natural Science Foundation of China (Grant No.31170896)Natural Science Foundation of Shandong Province (Grant No.ZR2009CMO32)
文摘The purpose of this study was to explore the triphasic mechanical properties of osteoarthritic cartilage with different pathological grades.First,samples of cartilage from rabbits with different stages of osteoarthritis (OA) were graded.Following this,the cartilage was strained by a swelling experiment,and changes were measured using a high-frequency ultrasound system.The result,together with fixed charge density and water volume fraction of cartilage samples,was used to estimate the uniaxial modulus of the cartilage tissue,based on a triphasic model.For the control cartilage samples,the uniaxial elastic modulus on the cartilage surface was lower than those in the middle and deep layers.With an increase in the OA grade,the uniaxial elastic modulus of the surface,middle and deep layers decreased.A significant difference was found in the surface elastic modulus of different OA grades (P<0.01),while no significant differences were identified for OA cartilages of Grades 1 and 2 in the middle and deep layers (P<0.01).Compared with Grades 1 and 2,there was a significant reduction in the elastic modulus in the middle and deep layers of Grade 3 OA cartilage (P<0.05).Overall,this study may provide a new quantitative method to evaluate the severity of OA using the mechanical properties of cartilage tissue.
基金Supported by the National Basic Research Program of China (Grant No. 2003CB716101)the National Natural Science Foundation of China (Grant No. 60772120)the Key National Science Foundation of China (Grant No. 30730026)
文摘For the segmentation of X-ray angiograms (XRA), the essential feature and the prior knowledge of angiographic image were analyzed, and a multi-feature based fuzzy recognition (MFFR) algorithm was proposed to infer the local vessel structure in this paper. Guided by the prior knowledge of artery vessel, a probability tracking operator (PTO) can rapidly track along the artery tree, and walk across the weak region or gaps because of disturbance or preprocessing to angiographic image. Another, the accurate measurement of the vascular axis-lines and diameters can be synchronously implemented in the tracking process. To correctly evaluate the proposed method, a simulated image of CAT and some clinical XRA images were used in the experimentations. The algorithms performed better than the conventional one: given one start-point, on average 92.7% of the visible segments or branches was automatically delineated; the correctness ratio of vessel structure inference reached to 90.0% on the average.