Biomedical Engineering: Applications, Basis and Communications

This study employs relational analysis and the GreyART network to identify and study the characteristics of electroencephalogram signals of sleep apnea syndrome (SAS). Seventeen raw electroencephalogram data records from the sleep database compiled by Massachusetts Institute of Technology (MIT) and Beth Israel Hospital (BIH) were used in conjunction with four wavelet decomposition steps to obtain the cD4 wavelet coefficient as input for the GreyART network. The GreyART network was then used for simulation training and testing in order to achieve the best recognition results. This study achieved an average recognition rate of 93.33% for electroencephalogram data record slp01b, and recognition rates during the training and testing stage for this record were 95.80% and 92.12%, respectively. This was the best recognition result for any of the 17 records. The overall average recognition rate for all 17 records was 78.10%. In comparison with past literature, this study's use of the GreyART network to recognize electroencephalogram signal characteristics of SAS possesses excellent reference value. To further reduce the costs and the physiological signal measurement items to make it easier for patients to use, this research also proposes to use a single type of physiological signals, electroencephalographic (EEG) signals, as the sole input as identification information to identify SAS diseases. EEG signal detection is utilized because it is nonintrusive, suitable for long-term monitoring and most importantly, it can be used to detect various types of abnormal physiological conditions in SAS, moods, sleep stages, heart rate abnormalities and mental states. In addition, constant monitoring of users in their familiar home environment can also be utilized as self-screening at home to reduce the burden of sleep medicine centers.

Diabetic maculopathy is one of the complications of diabetes mellitus that is considered as one of the major cause of vision loss among people around the world. Compulsory screening of eye will help to identify the maculopathy at early stage and reduce the risk of severe vision loss. A new automated method for the detection and grading of diabetic maculopathy severity level without any manual intervention is presented. Based on the location of exudates in marked macular region the severity level is classified into mild, moderate and severe. Digital color retinal images at different levels of maculopathy were used to evaluate the method. An overall sensitivity of 95.6% and specificity of 96.15% were achieved by the method.

Every year many people suffer from knee injuries. Previous studies on patients with knee injuries have shown that about 40% of knee injuries are Ligament injuries, and about 50% of the ligament injuries are the Anterior Cruciate Ligament (ACL) injuries. Along with other methods, knee arthrometers are widely used to diagnose ACL injuries. In the current research, a knee arthrometer was designed and developed to provide a reliable and repeatable measurement of knee laxity under anterior–posterior applied loads. Test–retest configurations to examine repeatability of the device resulted in less than 1.5-mm difference for more than 97% of tests under applied loads of up to 90 N. These tests included 166 tests on the left knees and 147 tests on the right knees of 37 healthy subjects. Also, this device was tested on 27 confirmed ACL ruptured patients, and the results were analyzed to find a better criterion than standard criteria to diagnose ACL rupture using knee arthrometers by finding specificity and sensitivity of the device using those criteria. Among the 20 criteria evaluated, a combination of side-to-side difference under 150 N of applied load, and CI@90-60 (compliance index calculated between 90 N, and 60 N) resulted in the best sensitivity (96.4%) and specificity (100%).

Surface modification is believed to be an effective way to control the biodegradation rate of magnesium alloys and improve their biological properties. In the present work, a calcium phosphate (Ca-P) coating was prepared on the AZ31B magnesium alloy by a chemical deposition method to integrate the mechanical advantages of the magnesium substrate and the good bioactivity of the ceramic coating. It was shown that the coating was mainly composed of magnesium and calcium phosphates. Scanning electron microscope coupled with the energy dispersive spectrum analyses showed that rough and crystallined Ca-P coatings with different Ca/P ratios and thickness were formed on the alloy by variation of deposition time. The corrosion resistance of AZ31B alloy was significantly improved by the Ca-P coating. Electrochemical impedance spectroscopy test was used to illustrate the reaction process of Ca-P coating on the alloy. Upon the above results, Ca-P formation mechanism on the AZ31B alloy was proposed. The heterogeneous nucleation and growth of the calcium phosphate coating may be catalyzed by the anodic dissolution of the magnesium alloy substrate in the early stage of deposition, and the deposition coating is mainly composed of the magnesium phosphate. Then calcium phosphate deposition on the alloy becomes dominant with the increase of time. Tensile test in simulated body environment results showed that the time of fracture and ultimate tensile strength for the coated AZ31B Mg alloy were higher than those of the uncoated, which is beneficial in supporting fractured bone for a longer time.

Background: Exogenous enzyme cannot cross the blood brain barrier to eliminate accumulated glycogen and brain involvement by Pompe disease is worth of attention before starting enzyme-replacement therapy.

Material And Methods: Before treatment, we recruited 10 infantile-onset Pompe patients and divided them into 2 groups. Group A (n = 6) had truncal hypotonia, while group B (n = 4) did not. The control group included another 10 age-matched subjects. The maps of first (EV1), second (EV2), and third eigenvalues (EV3), trace apparent diffusion coefficient, and fractional anisotropy (FA) were generated. We compared regions of interest in the right cerebellar peduncle, central pons, posterior limb of the right internal capsule, right thalamus, right superior corona radiata near the level of the lateral ventricular bodies, and genu and splenium of the corpus callosum between the Pompe patients and control subjects.

Results: On diffusion tensor images (DTIs), we found increased EV3 at the central pons (0.570 ± 0.116 versus 0.434 ± 0.154, p = 0.03) and genu of the corpus callosum (0.707 ± 0.181 versus. 0.447 ± 0.184, p = 0.03) in group A, but not in group B, as compared with age-matched controls. EV2 (0.961 ± 0.241 versus. 0.755 ± 0.138, p = 0.04) increased significantly but FA (0.485 ± 0.125 versus. 0.716 ± 0.121, p = 0.03) decreased significantly at the splenium of the corpus callosum of group A patients both not in group B.

Conclusion: In our Pompe patients younger than nine months, DTIs could not disclose significant changes of diffusion indices at the supratentorial white matters in group B patients without truncal hypotonia. Further progressive hypomyelination of supertentorial white matter may be prevented with adequate and early enzyme replacement treatment applied to infant-onset Pompe patients.

Gender and handedness differences in cognitive functions and brain structures are well recognized. Recent research has reported different white matter structures between male and female subjects. Yet it is unknown whether the gender and handedness effects on different white matter tracts are comparable or disparate. In this study, we focus on three main tracts in the fronto-striato-thalamic circuit, namely, the cingulum bundles (CG), fornices (FXs) and anterior thalamic radiations (ATR). These are the primary connections among the frontal lobe, the limbic system, and the thalamus, integrating functions of emotion control, memory, and decision-making. A total of 40 healthy adults were recruited in this study. There was no significant difference in demographic variables between males and females. Images were acquired on a 3-T Magnetic resonance imaging (MRI) system with an eight-channel head coil. The diffusion spectrum imaging (DSI) experiment was performed by applying 203 diffusion gradient vectors. DSI maps the angular distribution of water molecule displacement by acquiring diffusion MR signals in a more comprehensive way. The theory of DSI is based on the Fourier transform relationship between diffusion MR signals and the average propagator of water molecule displacement. Isotropic spatial resolution was obtained by setting both in-plane and through-plane resolutions as 2.7 mm. A total of 45 trans-axial slices were acquired encompassing the whole brain. DSI analysis was computed based on the Fourier relationship between diffusion echo signals and the probability density function (PDF). Fiber tracking was used to define the targeted tracts. All fiber orientations of the nearest voxels were used to decide the proceeding orientation for the next step. Tracking stopped if there was no coinciding orientation in the nearest voxels. Mean path analysis, a method that projected the anisotropy of PDF [generalized fractional anisotropy (GFA)] onto a single mean path of the specific white matter tract bundle, was used to analyze subtle changes in microstructure coherence along individual tract bundles. The asymmetric differences of targeted tracts were assessed statistically by calculating GFA values and lateralization indices (LIs). The handedness factor of the LI values in CG and ATR showed a trend for significance. The gender factor of the LI values was investigated in FX also. Different white matter tract bundles manifested different degrees of gender effect on GFA distributions. Our results suggest that the gender and handedness factors should be considered when one evaluates the impairment of the fronto-striato-thalamic circuit.

Neurons within spinal cord injury (SCI) are prevented from regeneration because of scar formation. Chondroitinase ABC (ChABC) was reported to promote functional recovery after spinal cord injury. However, the mechanism and the role of ChABC in the recovery are not clear. In this research, we used second harmonic generation (SHG) and two-photon excitation fluorescence (2PEF) images as probes to observe cell–matrix interaction on fibrosis after SCI followed by ChABC treatment. According to our experimental results, the enzyme ChABC could decrease cystic formation dramatically and consequently allow the spinal cord to regenerate. Using immunohistological analysis, we found that treatment with ChABC at the lesion area resulted in fewer chondroitin sulfate proteoglycans (CSPGs) remaining, longer axonal re-growth, and more new developmental neurons. Furthermore, ChABC 1 U/ml was more effective than 5 U/ml treatment. Using the noninvasive technology, SHG and 2PEF images, we could observe cell–matrix interaction clearly, not only in fixed samples but also in unfixed ex vivo samples. This technology presents a potential for clinical use in the near future.

Continuously monitoring patient's cardiac performance during anesthesia induction and intubations is significant and essential in order to control the risk of anesthesia and intubations, because almost all anesthetic agents decrease myocardial loading conditions and contractility, and bring reversible and irreversible ischemic myocardial damage. A noninvasive, high benefit/cost ratio, easy operating and continuous cardiac function evaluation is still in high demand in clinical anesthesia monitoring system. Although phonocardiography could be a promising alternative cardiac function evaluation tool, the impact of general anesthesia and endotracheal intubations on cardiac performance has seldom been studied clinically by phonocardiogram. In this pilot research, we continuously monitored the heart sound of 103 patients from rest state to anesthesia induction state and to intubations state by phonocardiogram combined with electrocardiograph. The amplitude and timing indicators of heart sound were compared at three states. The results showed that the amplitude of first heart sound S1 and second heart sound S2, systole pressure, diastole pressure and heart rate fell down obviously while S1/S2, the diastole duration D and the ratio of diastole to systole duration D/S increased obviously when patients were anesthetized. On the contrary, the indicators rebounded greatly but still could not recover to the level of baseline shortly after endotracheal intubations.

Contrast-Enhanced Magnetic Resonance Imaging (CE-MRI) has been widely used in the diagnosis of lesions. Many contrast agents with various chemical and pharmacokinetic properties have been developed for clinical use. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) after the contrast agent administration depend on many factors, e.g. category and injected dosage of contrast agents, field strength of magnetic resonance (MR) scanner, slew rate of gradient, type of radiofrequency coil, reconstruction algorithm, pulse sequences, and so on. Gadovist is a newly developed contrast agent with high formulation of 1.0 M. It has been used in MR angiography and perfusion studies. The aim of this study is to investigate the optimal concentrations of Gadovist in MR T₁-weighted (T1W) images from phantom study and computer simulation. A phantom made of 21 test tubes with various concentrations of Gadovist (0–160 mM) was investigated. All the studies were performed on a 1.5-T clinical whole-body scanner. Four T1W pulse sequences, including two-dimensional spoiled gradient echo (2DSPGR), three-dimensional fast spoiled gradient echo (3DFSPGR), conventional spin echo (CSE), and inversion recovery (IR) were employed to produce T1W images. The CNR values were calculated from regions of interest (ROIs) of all test tubes and the optimal concentration for each pulse sequence was determined. The T₁ and T₂ values of the phantom were also measured to obtain the relaxivities (r₁ and r₂). Afterward, the optimal concentration for each pulse sequence could be obtained from computer simulation by using the r₁ and r₂ values. The results showed that the measured optimal concentrations for 2DSPGR, 3DFSPGR, CSE and IR are 10, 20, 2.5, and 2.5 mM, respectively. The r₁ and r₂ values of the Gadovist phantom are 4.1 and 5.7 mM^-1s^-1, respectively. The optimal concentrations obtained from computer simulation are 13.5, 22.8, 2.0, and 2.7 mM for 2DSPGR, 3DFSPGR, CSE, and IR, respectively. The optimal concentrations obtained from computer simulation and phantom study are in good agreement.

Chondroitin sulfate C (CSC) is an important extracellular matrix (ECM) component of native cartilage tissue. Since ECM is considered to play an important role in guiding proper cellular functions, such as proliferation, differentiation, migration, synthesis or degradation of ECM, in specific tissues, we would like to elucidate the effects of CSC on chondrocytes are cultured on type-II collagen (COL II) scaffolds in this study. In particular, we want to investigate if the oligosaccharides of CSC (O-CSC) have much stronger effects on the chondrocytes. In this in vitro study, human articular chondrocytes were cultured on porous scaffolds made of COL II, cross-linked by genipin. Media containing different molecular weights of CSC were used to cultivate the cells. The results were examined mainly from the gene expression profiles of the cultured cells. The expression levels of several genes were examined by real-time PCR. These included genes of COL II, aggrecan, SRY-related high mobility group-box gene 9 (SOX9) and cartilage oligo matrix protein (COMP), alkaine phosphtase (ALP), a disintegrin and metalloproteinases with thrombospondin motifs 4 (ADAMTS-4), a disintegrin and metalloproteinases with thrombospondin motifs 5 (ADAMTS-5), matrix metalloproteinases 3 (MMP-3) and tissue inhibitors of metalloproteinases 3 (TIMP-3). The results suggested that O-CSC is more potent in upregulating genes that promote chondrogenesis and downregulating genes that degrade cartilage ECM. The results suggest low-molecular-weight glycosaminoglycans may have therapeutic values in osteoarthritis treatment and may lead to further understanding of the basic mechanism of the interactions between the chondrocytes and their ECM.