Biomedical Engineering: Applications, Basis and Communications

The present work aims to simulate and predict the molecular pathway of Parkinson’s disease (PD) initiated by environmental stress. It is designed to predict how protein aggregation and Lewy body (LB) formation leads to dopamine toxicity finally leading to cell death. The Mechanistic electronic modeling using Digital-Analog hybrid technique has been designed and implemented using MULTISIM 8.0 (National Instruments, USA) to simulate and predict the dynamics of PD pathway under environmental stress condition. The electronic network is initiated through an analog comparator circuit that compares the long-term environmental alterations with the cellular set point level of the molecular kinetics. The pattern of neuronal firing is simulated with the help of analog electronic circuit. The simulation results show a slow progressive rise in $\alpha$-synuclein/LB/dopamine toxicity level within the neuronal cells, which is comparable to published experimental and modeling studies associated with PD. Finally, cell death is demonstrated, which leads to neurodegeneration. In conclusion, our model allows a straightforward implementation of qualitative representation for systems where the network topology or pathway is at least moderately known.

A challenging issue that has emerged regarding nonlocal means filtering based on Bayesian formulation in order to remove noises from ultrasound images is the determination of the optimal parameters of this filtration without the involvement of users concurrently before the start of the filtration. This issue is effective in both the filtration quality and the time required for process. This paper, presents an algorithm based on optimization algorithm in order for automatic and concurrent determination of the optimized parameters of this filter. The intravascular ultrasound (IVUS) images used for experiments and evaluation of the results have been taken from seven different individuals. The resolution of these images is $500*500$ pixels that is prepared by a transducer at a frequency of 30Mhz at 0.55m/s. The proposed algorithm works by combining nonlocal means filtering based on Bayesian formulation with genetic optimization algorithm. The cost function of the genetic algorithm is introduced based on the intended filter. In order to evaluate the algorithm proposed in this paper, a two-stage evaluation process was. At the first stage examinations, 50 IVUS images were recorded in 50 experiments of the applied proposed algorithm. The values of evaluation criteria and output images were then recorded and organized in a descending order. Ten preliminary groups of these parameters that had the best results in terms of the intended criteria were chosen for the second stage experiments. The second stage includes 30 experiments on 30 images not seen so far by the proposed algorithm. The details of the results are provided within the paper text extensively together with the obtained tables. In this paper, we have tried to simplify the way nonlocal means filtering should be used to improve the quality of intravascular ultrasound (IVUS) images. To this end, the algorithm proposed in this research calculates the optimal values of the parameters of this filter before filtration automatically with no user involvement. It also carries out the filtration using the optimal values of parameters that are the outputs of the proposed algorithm thereby increasing the quality of filtration by optimized parameters.

A novel poly[($\epsilon$-CL)-co-(GA-alt-L-Asp)] with improved hydrophilicity was prepared. The monomer 3(S)-[(benzyloxycarbony)methyl]-1,4-dioxane-2,5-dione (BMD) was prepared from aspartic acid. The polymer was obtained by ring-opening polymerization of $\epsilon$-caprolactone ($\epsilon$-CL) and BMD. Poly[($\epsilon$-CL)-co-(GA-alt-L-Asp)] was synthesized by deprotection. The structure and properties of the polymer were characterized using ¹H nuclear magnetic resonance, gel permeation chromatography, and differential scanning calorimetry. The melting point and melting enthalpy of the polymer decreased with the increase of BMD. The structural regularity of polycaprolactone was destroyed by the BMD. A laminin-derived peptide [i.e., Arg-Gly-Asp (RGD)] was covalently tethered to the carboxyl groups and the peptide-grafted films. Results indicated that the addition of RGD had beneficial effects for cell growth, as shown by scanning electron microscopy.

Despite their frequent use in our daily life, the expansion and reduction of images are among the least studied research areas in the literature. That is why the present research paper undertakes the study of the different techniques used for reducing and enlarging images, whose combination will be a new protocol (REPro) for the transmission of medical images. The proposed approach consists in reducing the image when sent and enlarging it when received, which allows for consumption saving of the bandwidth allocated to the diagnostics service. To do so, the performance of our new protocol was tested for the transfer of scars images (color images) and ultrasound images (grayscale images) in terms of the resemblance between the original image, on one hand, and the reduced and then enlarged one, on the other hand.

According to statistics in Taiwan, the proportion of students engaged in regular exercise has declined drastically with the increase in education level. This study thus aims to provide a platform for monitoring of group cardiorespiratory fitness to allow users such as teachers or coaches to easily monitor a group’s exercise condition, intensity and duration to increase exercise efficiency, promote exercise motivation and reduce exercise risk. Based on group measurement concept and wearable chest strap textiles integrated with heart rate monitoring devices, teachers or coaches can immediately acquire and display all heart rate information on a notebook computer together with synchronous field projection display. The acquired heart rate data can also be automatically recorded and analyzed to assist in assessing the physical fitness. Our proposed platform aims to monitor the cardiorespiratory fitness in group mainly for college students and young office worker. To validate the stability of our platform in the long term, we recruited the college students in a physical fitness class, 35 in total, as the subjects for long term observation. In the experiments the subjects are divided into “varsity group” and “sedentary group” according to whether they are with or without regular exercise habits. Subjects wearing chest straps were instructed to take the 3-minute Step Test and the 5-minute constant intensity exercise test. The results show that the “varsity group” has a lower resting heart rate ($67.8\pm 6.1$bpm vs. $80.6\pm 2.4$bpm), a lower exercise heart rate ($138.8\pm 9.2$bpm vs. $179.1\pm 6.7$bpm) and a lower mean heart rate ($131.5\pm 8.2$bpm vs. $160.1\pm 7.8$bpm). The “Varsity group” also has a higher heart rate recovery percentage at the first minute ($33.8\pm 5.0\%$ vs. $19.0\pm 2.5\%$) and the second minute ($43.9\pm 5.1\%$ vs. $30.4\pm 2.7\%$). Moreover, all these indexes have a high correlation with the fitness index in the 3-minute Step Test, among which the percentage of heart rate recovery in the first minute shows the highest positive correlation ($r=0.948$, $p<0.05$). Our wearable heart rate monitoring system can thus be deemed as effective to provide a platform for measurement of group heart rates and for assessment of cardiorespiratory fitness.

There is ambiguity on the quantitative validity of the predictions revealed by musculoskeletal models for muscle forces. This study investigated the consistency between the predictions of a musculoskeletal model of the upper limb and the experimental data for a number of different subjects and functional tasks. Six normal subjects performed isokinetic eccentric or isotonic concentric contraction tests of the wrist muscles in well controlled conditions, using a robotic apparatus, and the net joint torque and angular velocities, as well as the surface electromyograms (EMG) signals of the muscles, were recorded. The experiments were then simulated using a parametric musculoskeletal model of hand and forearm, scaled for each subject. Muscle activation was determined based on the optimization of a polynomial or min-max objective function. Comparison of the model predictions with the normalized EMGs revealed more consistent results for the polynomial objective function. In general, the model could reflect the change of the net joint torque on the activation level, but the effects associated with the velocity of movement were not sufficiently reflected. Stronger correlations between model predictions and normalized EMGs, were obtained for subjects with smaller body mass indices (BMIs), 0.738, and those who experienced higher muscular excitations, 0.908. The sensitivity analysis of the model also indicated a high sensitivity (9.5%) to the joint torque but a minimal sensitivity (0.3%) to the joint velocity. The sensitivity indices for the muscle’s length and physiological cross-sectional area (PCSA) were 11.2 and 5.3%, respectively. It was concluded that our musculoskeletal model was highly sensitive to the anatomical data, as well as the muscles’ excitation levels, but not to the contraction velocity.

According to statistics, up to 40% of emergency admissions are due to chest tightness or chest pain. However, merely based on the patient’s current symptoms such as chest pain, it is difficult for a physician to give an instant diagnosis as most cardiovascular diseases are chronic. To address this issue, it is necessary to provide a set of tools to indicate the patient’s status during hospitalization to help the physician in diagnosis. It is thus our primary objective to design and develop a wearable heart rate monitoring system and prediction tool that can measure the patient’s heart rate parameters, allow him/her to move around easily, and which also can effectively improve the medical personnel’s working efficiency. This research utilizes conductive filament to design textile to integrate electric circuit with clothing. Using a conductive vest and chest belt that can be worn comfortably, our system can continuously record patients’ physiological index parameters during their hospitalization. Physiological index parameters of multiple patients can then be transmitted wirelessly and recorded in a physician-end computer. At the end of their hospitalization, the patient’s original physiological indices together with the recorded heart rate variability (HRV) parameters can then be summarized to assess the risk score of their discharging from hospital. This paper adopts the concept of TIMI risk score, while adding every index of HRV measured when subjects are hospitalized. The risk score can hence be used to provide emergency physicians as a basis for an early prognosis and subsequently a better hospital-discharging assessment of patients with chest pain. The accuracy of the proposed prognosis has been verified with the 3-day and 30-day recall rate of the patients and the result has been shown to be promising for chest pain patients in emergency admission units.

Back pain can affect up to 65% of the American population and cost the health care system approximately fifty billion dollars each year. Due to the difficulty with recording spine/trunk movement, several methods and models exist. The myriad of methods and the need for understanding of spine/trunk motion has led to a lack in a ‘gold-standard’ of treatment for individuals with back pain. Therefore, the purpose of this study was to examine the effect of different activities of daily living on the kinematics of individual trunk segments in young adults to determine how common ambulatory tasks will alter trunk motion compared to level walking.

Young healthy adults completed, in a random order, four activities of daily living: level walking, obstacle crossing, stair ascent and descent using a previously validated model. Subjects were outfitted with a full body marker set which included a segmented trunk. Multi-segmented trunk angles between the three inferior segments, sacrum to lower lumbar [SLL], lower lumbar to upper lumbar [LLUL] and upper lumbar to lower thorax [ULLT], were calculated and compared between tasks. Peak flexion angles, instance of peak angle and range of motion were analyzed.

The overall hypothesis that different spine levels will have altered kinematics during various activities of daily living was supported. Stair descent had smaller peak flexion angles than obstacle crossing and stair ascent. The instance of peak angle were different depending on trunk angle and daily task. The most inferior trunk angle — Sacrum-to-Lower Lumbar — had the largest range of motion during all four tasks in all three (sagittal, frontal and transverse) planes of motion.

This study was able to show how various activities of daily living produce different motions in the three inferior segments of a multi-segmented trunk method. The results of this study are the first steps in understanding how the trunk responds on a daily basis and how those responses could lead to back pain.

Dual-task obstacle crossing gait paradigms are commonly adopted to examine how attentional demands are associated with sensory-motor processing during obstacle crossing. Various attention tasks have been used with mixed findings. This raises a question whether and how different attention tasks would affect motor function differently. Therefore, we examined and compared the effects of two visual attention tasks on obstacle crossing in healthy young adults. In the first experiment, 10 young adults responded to a 200ms visuospatial attention task during the approaching phase of obstacle crossing. In the second experiment, another 10 young adults responded to a visual Stroop task while approaching and crossing an obstacle. In both experiments, subjects completed an obstacle crossing only, a visual attention only, or a dual-task obstacle crossing condition in a random order. Dual-task costs were calculated for each visual attention task on the accuracy rates, toe-obstacle clearances and gait velocities. Two tripping incidences occurred only in the dual-task condition with visuospital attention task. Trailing toe-obstacle clearance reduced in the dual-task condition with visuospital attention task, but toe-obstacle clearances of both limbs increased in the dual-task condition with Stroop task. Gait velocities were not affected by the visuospatial attention task but were significantly reduced when concurrently performing the Stroop task. Dual-task costs were significantly different between two experiments on the gait velocity and toe clearances, but not on the accuracy rate. Our findings demonstrated that different visual attention tasks lead to distinct modifications on obstacle crossing behaviors.

Fusion has been the gold standard treatment for treating lumbar degenerative disc disease. Many clinical studies have demonstrated that adjacent segment degeneration was observed in patients over time. Various instrumentations of pedicle screw-based stabilization systems have been investigated using numerical approaches. However, numerical models developed in the past were simplified to reduce computational time. The aim of this study was to evaluate and to compare the biomechanical performance of rigid, semi-rigid, and dynamic posterior instrumentations using a more realistic numerical model. Three-dimensional nonlinear finite element models of the T11-S1 multilevel spine with various posterior instrumentations were developed. The intersegmental rotation, the maximum disc stress, and the maximum implant stress were calculated. The results indicated that the rigid instrumentation resulted in greater fixation stability but also a greater risk of adjacent segment degeneration and implant failure. The biomechanical performance of the dynamic instrumentation was closer to that of the intact spine model compared with the rigid and semi-rigid instrumentations. The results of this study could help surgeons understand the biomechanical characteristics of different posterior instrumentations for the treatment of lumbar degenerative disc diseases.