Objective To set up the experimemtal model with superior segmentalbone defect in acetabulum and implant the three-fin acetabular component, and examine the Von Mises stresses of pelvis bone with simulating single leg position in vitro using rosette strain gages method(RSGD). Methods Four kinds of three-fin components were made based on measurement of diameter, depth and roof thickness of acetabular specimens. These kinds of threefin acetabular components based on spreaded degrees of lateral fins(0,36,45 and 60°). The superiorsegmental bone defect of acetabulum in 4 cadaver pelvis specimens was made,then simulated the actual position to place implant into acetabular bone.A blank control group was set up.After being fit up the 7 sets of rosette strain gages,then specimen to test the pelvic Von Mises stresses simulating the static load of single leg on the mechanic machine.Progressive load was graded into 150, 300,450, 600, 750 and 900 N.We obtained the strains informations about loaded andun-loaded pelvis bone. Results Based on computed the strains informations,we were informed the Von Mises stresses about pelvis bone.The maximal Von Mises stresses of selected local position was 6.93 MPa and the minimal Von Mises stresses of selected local position was 1.08 MPa. Conclusion Providing the data about the mainpart of threefin acetabular component to optimize spreaded degrees of lateral fins.
ObjectiveTo explore the distribution of multidrug resistant organism in neonates admitted to the hospital through various ways, and analyze the risk factors in order to avoid cross infection of multidrug resistant organism in neonatology department. MethodsA total of 2 124 neonates were monitored from January 2012 to July 2013, among which 1 119 were admitted from outpatient department (outpatient group), 782 were transferred from other departments (other department group), and 223 were from other hospitals (other hospital group). We analyzed their hospital stays, weight, average length of stay, and drug-resistant strains, and their relationship with nosocomial infection. ResultsAmong the 105 drug-resistant strains, there were 57 from the outpatient group, 27 from the other department group, and 21 from the other hospital group. The positive rate in the patients transferred from other hospitals was the highest (9.42%). Neonates with the hospital stay of more than 14 days and weighing 1 500 g or less were the high-risk groups of drug-resistant strains in nosocomial infection. Drug-resistant strains of nosocomial infection detected in the patients admitted through different ways were basically identical. ConclusionWe should strengthen screening, isolation, prevention and control work in the outpatient neonate. At the same time, we can't ignore the prevention and control of the infection in neonates from other departments or hospitals, especially the prevention and control work in neonates with the hospital stay of more than 14 days and weighing 1 500 g or less to reduce the occurrence of multiple drug-resistant strains cross infection.
Objective By observation of the diameter, progression rate, wall thickness, and the opening angle of the abnormal aortic of abdominal aortic aneurysm (AAA) in rats, to observe the effect of saturated hydrogen saline on residual strain of AAA rats, and to investigate its inhibition effect on AAA formation. Methods Twenty healthy male Sprague Dawley rats (weighing, 200-220 g) were randomly divided into 2 groups, which was made the AAA model by infiltration of the abdominal arota with 0.5 mol/L calcium chloride. Saturated hydrogen saline (5 mL/kg) or saline (5 mL/kg) was injected intraperitoneally in the experimental group or control group respectively, every day for 28 days. At 28 days, the diameter, progression rate, wall thickness, and opening angle of the abnormal aorta were mearsured. The aortic tissue was harvested for histological examination (HE staining and aldehyde-fuchsin staining). Results At 28 days after operation, the diameter of abnormal aorta in 2 groups were significantly higher than preoperative ones (P lt; 0.05), the progression rate in experimental group (65% ± 15%) was significantly lower than that in control group (128% ± 54%) (t=3.611, P=0.005). The opening angle and the wall thickness in experimental group were (88.78 ± 29.20)° and (0.14 ± 0.03) mm respectively, had significant differences when compared with the values in control group [(44.23 ± 28.52)° and (0.36 ± 0.05) mm respectively] (P lt; 0.01). The integrity and continuity of the aortic wall in experimental group were superior to that in the control group. Compared with the control group, the injury of elastic fiber in aortic wall and the infiltration of inflammation were all reduced. Conclusion Saturated hydrogen saline can maintain good mechanical properties and reduce dilatation of the aorta by increasing residual strain and reducing the remodeling of it.
The requirement for unconstrained monitoring of heartbeat during sleep is increasing, but the current detection devices can not meet the requirements of convenience and accuracy. This study designed an unconstrained ballistocardiogram (BCG) detection system using acceleration sensor and developed a heart rate extraction algorithm. BCG is a directional signal which is stronger and less affected by respiratory movements along spine direction than in other directions. In order to measure the BCG signal along spine direction during sleep, a 3-axis acceleration sensor was fixed on the bed to collect the vibration signals caused by heartbeat. An approximate frequency range was firstly assumed by frequency analysis to the BCG signals and segmental filtering was conducted to the original vibration signals within the frequency range. Secondly, to identify the true BCG waveform, the accurate frequency band was obtained by comparison with the theoretical waveform. The J waves were detected by BCG energy waveform and an adaptive threshold method was proposed to extract heart rates by using the information of both amplitude and period. The accuracy and robustness of the BCG detection system proposed and the algorithm developed in this study were confirmed by comparison with electrocardiogram (ECG). The test results of 30 subjects showed a high average accuracy of 99.21% to demonstrate the feasibility of the unconstrained BCG detection method based on vibration acceleration.
Constrained spherical deconvolution can quantify white matter fiber orientation distribution information from diffusion magnetic resonance imaging data. But this method is only applicable to single shell diffusion magnetic resonance imaging data and will provide wrong fiber orientation information in white matter tissue which contains isotropic diffusion signals. To solve these problems, this paper proposes a constrained spherical deconvolution method based on multi-model response function. Multi-shell data can improve the stability of fiber orientation, and multi-model response function can attenuate isotropic diffusion signals in white matter, providing more accurate fiber orientation information. Synthetic data and real brain data from public database were used to verify the effectiveness of this algorithm. The results demonstrate that the proposed algorithm can attenuate isotropic diffusion signals in white matter and overcome the influence of partial volume effect on fiber direction estimation, thus estimate fiber direction more accurately. The reconstructed fiber direction distribution is stable, the false peaks are less, and the recognition ability of cross fiber is stronger, which lays a foundation for the further research of fiber bundle tracking technology.
Sleep-related breathing disorder (SRBD) is a sleep disease with high incidence and many complications. However, patients are often unaware of their sickness. Therefore, SRBD harms health seriously. At present, home SRBD monitoring equipment is a popular research topic to help people get aware of their health conditions. This article fully compares recent state-of-art research results about home SRBD monitors to clarify the advantages and limitations of various sensing techniques. Furthermore, the direction of future research and commercialization is pointed out. According to the system design, novel home SRBD monitors can be divided into two types: wearable and unconstrained. The two types of monitors have their own advantages and disadvantages. The wearable devices are simple and portable, but they are not comfortable and durable enough. Meanwhile, the unconstrained devices are more unobtrusive and comfortable, but the supporting algorithms are complex to develop. At present, researches are mainly focused on system design and performance evaluation, while high performance algorithm and large-scale clinical trial need further research. This article can help researchers understand state-of-art research progresses on SRBD monitoring quickly and comprehensively and inspire their research and innovation ideas. Additionally, this article also summarizes the existing commercial sleep respiratory monitors, so as to promote the commercialization of novel home SRBD monitors that are still under research.
Abstract： Objective To use tissue Doppler strain rate imaging to evaluate the impact of low dose dopamine and milrinone on systolic and diastolic function of the left ventricle of patients undergoing heart valve replacement. Methods Forty patients undergoing selective heart valve replacement in West China Hospital of Sichuan University between March and May 2011 were included in this study. All the patients were randomized into 2 groups with 20 patients in each group： milrione group and dopamine group. After anesthesia induction and before cardiopulmonary bypass setup， left ventricular ejection fraction （LVEF） was measured by echocardiography. Tissue Doppler strain rate imaging was used to measure the left ventricular lateral wall and midventricular segment from the four-chamber view， which was compared with Doppler parameters. Results LVEF， ratio of early-diastolic to end-diastolic velocity （E/A） of transmitral flow， ratio of mitral inflow velocity to early diastolic velocity in the annulus （E/Et） of both 2 groups were significantly different between before and after dopamine and milrinone administration （P＜0. 05）. In the milrinone group， 4 segments systolic peak velocity （Vs）， 1 segment early diastolic peak velocity （Ve）， 4 segments late diastolic peak velocity （Va）， 3 segments Ve/Va ratio， 2 segments systolic peak strain rate （SRs）， 2 segments late diastolic peak strain rate （SRa）， and 3 segments early diastolic peak strain rate SRe/SRa ratio after dopamine and milrinone administration were significantly higher than those before dopamine and milrinone administration （P＜0. 05）. In the dopamine group， 4 segments systolic peak velocity （Vs）， 1 segment Ve， 4 segments Va， 1 segment Ve/Va ratio， 2 segments SRs， 1 segment SRe， 1 segment SRa， and 1 segment SRe/SRa ratio after dopamine and milrinone administration were significantly higher than those before dopamine and milrinone administration （P＜0.05）. To compare the milrione group and dopamine group after medication administration， 2 segments Vs， 4 segments Va， 1 segment SRe， 1 segment SRa， 2 segments Ve/Va ratio， and 2 segments SRe/SRa ratio of the milrione group were significantly higher than those of the dopamine group （P＜0.05）， and 1 segment Vs， two segments SRs of the milrione group were significantly lower than those of the dopamine group （P＜0.05）. Conclusion Both milrinone and dopamine can improve left ventricular systolic function of perioperative patients undergoing heart valve replacement assessed by tissue Doppler strain rate imaging， while milrinone can improve the diastolic function of the left ventricle on the long axis more significantly.
To evaluate the fatigue behavior of nitinol stents, we used the finite element method to simulate the manufacture processes of nitinol stents, including expanding, annealing, crimping, and releasing procedure in applications of the clinical treatments. Meanwhile, we also studied the effect of the crown area dimension of stent on strain distribution. We then applied a fatigue diagram to investigate the fatigue characteristics of nitinol stents. The results showed that the maximum strain of all three stent structures, which had different crown area dimensions under vessel loads, located at the transition area between the crown and the strut, but comparable deformation appeared at the inner side of the crown area center. The cause of these results was that the difference of the area moment of inertia determined by the crown dimension induced the difference of strain distribution in stent structure. Moreover, it can be drawn from the fatigue diagrams that the fatigue performance got the best result when the crown area dimension equaled to the intermediate value. The above results proved that the fatigue property of nitinol stent had a close relationship with the dimension of stent crown area, but there was no positive correlation.
We aimed to establish an optical coherence tomography (OCT) system to measure the strain of blood vessels. A general OCT system was constructed firstly and its reliability was confirmed by comparing the OCT imaging of the porcine coronary and the corresponding histological slices. The strain of the porcine coronary was induced by static flow pressure and correlation algorithm was used to calculate the strain field of blood vessels within OCT images. The results suggest that bright-dark stratification of blood vessels displayed in OCT images is consistent with the intima and media layers of histological image. Furthermore, the strain of media layer is greater than that of the intima layer under the same static pressure. The optical coherence imaging system could not only measure the histological structure of the blood vessels, but also qualify the vessel strain under flow pressure.
By using Urist s method four types of BMG from the long bones of the rabbit、 pig、sheep、 and human being were prepared. Each of them was implanted into the pectoralis and thigh muscles in 25 adult rats, respectiely. Two-eight weeks after implantation, the unoreaction and inductive osteogensis potential in the tissues were observed under mieroscope. The result showed that aBMG had inductive osteogenesis potential. However, rejection in varying digree existed around aBMG. It was important to further decrease the antingenicity digree exised around a BMG . and enhance its osteogennic potential before the possibility of its clinical application.