Search for: pathophysiological
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    Search for critical loading condition of the spine-A meta analysis of a nonlinear viscoelastic finite element model

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 8, Issue 5 , 2005 , Pages 323-330 ; 10255842 (ISSN) Wang, J. L ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
    The relative vulnerability of spinal motion segments to different loading combinations remains unknown. The meta-analysis described here using the results of a validated L2-L3 nonlinear viscoelastic finite element model was designed to investigate the critical loading and its effect on the internal mechanics of the human lumbar spine. A Box-Behnken experimental design was used to design the magnitude of seven independent variables associated with loads, rotations and velocity of motion. Subsequently, an optimization method was used to find the primary and secondary variables that influence spine mechanical output related to facet forces, disc pressure, ligament forces, annulus matrix... 

    Synchronizability of EEG-based functional networks in early alzheimer's disease

    , Article IEEE Transactions on Neural Systems and Rehabilitation Engineering ; Volume 20, Issue 5 , 2012 , Pages 636-641 ; 15344320 (ISSN) Tahaei, M. S ; Jalili, M ; Knyazeva, M. G ; Sharif University of Technology
    IEEE  2012
    Recently graph theory and complex networks have been widely used as a mean to model functionality of the brain. Among different neuroimaging techniques available for constructing the brain functional networks, electroencephalography (EEG) with its high temporal resolution is a useful instrument of the analysis of functional interdependencies between different brain regions. Alzheimer's disease (AD) is a neurodegenerative disease, which leads to substantial cognitive decline, and eventually, dementia in aged people. To achieve a deeper insight into the behavior of functional cerebral networks in AD, here we study their synchronizability in 17 newly diagnosed AD patients compared to 17 healthy... 

    Fluid–structure interaction simulation of a cerebral aneurysm: effects of endovascular coiling treatment and aneurysm wall thickening

    , Article Journal of the Mechanical Behavior of Biomedical Materials ; Volume 74 , 2017 , Pages 72-83 ; 17516161 (ISSN) Shamloo, A ; Nejad, M. A ; Saeedi, M ; Sharif University of Technology
    In the present study, we investigate the effect of the hemodynamic factors of the blood flow on the cerebral aneurysms. To this end, a hypothetical geometry of the aneurysm in the circle of Willis, located in the bifurcation point of the anterior cerebral artery (ACA) and anterior communicating artery (ACoA) is modeled in a three-dimensional manner. Three cases are chosen in the current study: an untreated thin wall (first case), untreated thick wall (second case), and a treated aneurysm (third case). The effect of increasing the aneurysm wall thickness on the deformation and stress distribution of the walls are studied. The obtained results showed that in the second case, a reduction in the... 

    Synthetic ECG generation and bayesian filtering using a Gaussian wave-based dynamical model

    , Article Physiological Measurement ; Volume 31, Issue 10 , 2010 , Pages 1309-1329 ; 09673334 (ISSN) Sayadi, O ; Shamsollahi, M. B ; Clifford, G. D ; Sharif University of Technology
    In this paper, we describe a Gaussian wave-based state space to model the temporal dynamics of electrocardiogram (ECG) signals. It is shown that this model may be effectively used for generating synthetic ECGs as well as separate characteristic waves (CWs) such as the atrial and ventricular complexes. The model uses separate state variables for each CW, i.e. P, QRS and T, and hence is capable of generating individual synthetic CWs as well as realistic ECG signals. The model is therefore useful for generating arrhythmias. Simulations of sinus bradycardia, sinus tachycardia, ventricular flutter, atrial fibrillation and ventricular tachycardia are presented. In addition, discrete versions of... 

    Drug delivery systems and materials for wound healing applications

    , Article Advanced Drug Delivery Reviews ; Volume 127 , 2018 , Pages 138-166 ; 0169409X (ISSN) Saghazadeh, S ; Rinoldi, C ; Schot, M ; Saheb Kashaf, S ; Sharifi, F ; Jalilian, E ; Nuutila, K ; Giatsidis, G ; Mostafalu, P ; Derakhshandeh, H ; Yue, K ; Swieszkowski, W ; Memic, A ; Tamayol, A ; Khademhosseini, A ; Sharif University of Technology
    Elsevier B.V  2018
    Chronic, non-healing wounds place a significant burden on patients and healthcare systems, resulting in impaired mobility, limb amputation, or even death. Chronic wounds result from a disruption in the highly orchestrated cascade of events involved in wound closure. Significant advances in our understanding of the pathophysiology of chronic wounds have resulted in the development of drugs designed to target different aspects of the impaired processes. However, the hostility of the wound environment rich in degradative enzymes and its elevated pH, combined with differences in the time scales of different physiological processes involved in tissue regeneration require the use of effective drug... 

    A novel distributed model of the heart under normal and congestive heart failure conditions

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 4 , 2013 , Pages 362-372 ; 09544119 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Conventional models of cardiovascular system frequently lack required detail and focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the cardiovascular system. It utilizes noninvasive blood flow and pressure seed data and temporal cardiac muscle regional activity to predict the operation of the heart under normal and congestive heart failure conditions. The analysis considers specific regions of the heart, namely, base, mid and apex of left ventricle. The proposed method of parameter estimation for hydraulic electric analogy model is recursive least squares algorithm. Based on simulation results and comparison... 

    Design and development of a hand robotic rehabilitation device for post stroke patients

    , Article Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference ; 2009 , Pages 5026-5029 ; 1557170X (ISSN) Rashedi, E ; Mirbagheri, A ; Taheri, B ; Farahmand, F ; Vossoughi, G. R ; Parnianpour, M ; Sharif University of Technology
    Robot-mediated rehabilitation is a rapidly advancing discipline that seeks to develop improved treatment procedures using new technologies, e.g., robotics, coupled with modern theories in neuroscience and rehabilitation. A robotic device was designed and developed for rehabilitation of upper limbs of post stroke patients. A novel force feedback bimanual working mode provided real-time dynamic sensation of the paretic hand. Results of the preliminary clinical tests revealed a quantitative evaluation of the patient's level of paresis and disability  

    Computer simulation of knee arthrometry to study the effects of partial ACL injury and tibiofemoral contact

    , Article 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08, Vancouver, BC, 20 August 2008 through 25 August 2008 ; 2008 , Pages 895-898 ; 9781424418152 (ISBN) Rahemi, H ; Farahmand, F ; Rezaeian, T ; Parnianpour, M ; Sharif University of Technology
    IEEE Computer Society  2008
    We simulated the knee arthrometry test to obtain a deeper understanding of the joint's stability behavior and interpret the arthrometric results more effectively. A 2D sagittal plane finite element model of the lower limb in the standard configuration of knee arthrometry was developed using ANSYS APDL. A detailed model of the knee joint was considered including the femoral articulating contour represented by an ellipse, the tibial plateau represented by a circular arc, and four major knee ligaments and their individual bundles represented by linear and nonlinear tensile springs. A deformable layer of articular cartilage was also considered over the tibial plateau to simulate the bones... 

    Individual differences in nucleus accumbens dopamine receptors predict development of addiction-like behavior: A computational approach

    , Article Neural Computation ; Volume 22, Issue 9 , 2010 , Pages 2334-2368 ; 08997667 (ISSN) Piray, P ; Keramati, M. M ; Dezfouli, A ; Lucas, C ; Mokri, A ; Sharif University of Technology
    Clinical and experimental observations show individual differences in the development of addiction. Increasing evidence supports the hypothesis that dopamine receptor availability in the nucleus accumbens (NAc) predisposes drug reinforcement. Here, modeling striatal-midbrain dopaminergic circuit, we propose a reinforcement learning model for addiction based on the actor-critic model of striatum. Modeling dopamine receptors in the NAc as modulators of learning rate for appetitive-but not aversive-stimuli in the critic-but not the actor-we define vulnerability to addiction as a relatively lower learning rate for the appetitive stimuli, compared to aversive stimuli, in the critic. We... 

    Rehabilitation after ACL injury: A fluoroscopic study on the effects of type of exercise on the knee sagittal plane arthrokinematics

    , Article BioMed Research International ; Volume 2013 , July , 2013 ; 23146133 (ISSN) Norouzi, S ; Esfandiarpour, F ; Shakourirad, A ; Salehi, R ; Akbar, M ; Farahmand, F ; Sharif University of Technology
    A safe rehabilitation exercise for anterior cruciate ligament (ACL) injuries needs to be compatible with the normal knee arthrokinematics to avoid abnormal loading on the joint structures. The objective of this study was to measure the amount of the anterior tibial translation (ATT) of the ACL-deficient knees during selective open and closed kinetic chain exercises. The intact and injured knees of fourteen male subjects with unilateral ACL injury were imaged using uniplanar fluoroscopy, while the subjects performed forward lunge and unloaded/loaded open kinetic knee extension exercises. The ATTs were measured from fluoroscopic images, as the distance between the tibial and femoral reference... 

    Lower extremity kinematic analysis in male athletes with unilateral anterior cruciate reconstruction in a jump-landing task and its association with return to sport criteria

    , Article BMC Musculoskeletal Disorders ; Volume 20, Issue 1 , 2019 ; 14712474 (ISSN) Norouzi, S ; Esfandiarpour, F ; Mehdizadeh, S ; Yousefzadeh, N. K ; Parnianpour, M ; Sharif University of Technology
    BioMed Central Ltd  2019
    Background: Return to sport (RTS) criteria are widely being used to identify anterior cruciate ligament reconstructed (ACLR) athletes ready to return to sportive activity and reduce risk of ACL re-injury. However, studies show a high rate of ACL re-injury in athletes who passed RTS criteria. This indicates that the current RTS criteria might not be sufficient to determine return to sport time in ACLR athletes. Previous studies have reported a close association between altered lower limb kinematics and ACL re-injury. However, it is not clear how lower extremity kinematics differs between ACLR athletes who passed the RTS-criteria and who failed. This study compared lower extremity kinematics... 

    Anxiety and cognitive load affect upper limb motor control in Parkinson's disease during medication phases

    , Article Annals of the New York Academy of Sciences ; Volume 1494, Issue 1 , 2021 , Pages 44-58 ; 00778923 (ISSN) Nodehi, Z ; Mehdizadeh, H ; Azad, A ; Mehdizadeh, M ; Reyhanian, E ; Saberi, Z. S ; Meimandi, M ; Soltanzadeh, A ; Roohi Azizi, M ; Vasaghi Gharamaleki, B ; Parnianpour, M ; Khalaf, K ; Taghizadeh, G ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Anxiety is among the most debilitating nonmotor symptoms of Parkinson's disease (PD). This study aimed to determine how PD patients with low and high levels of anxiety (LA-PD and HA-PD, respectively) compare with age- and sex-matched controls at the level of motor control of reach-to-grasp movements during single- and dual-task conditions with varying complexity. Reach-to-grasp movement kinematics were assessed in 20 LA-PD, 20 HA-PD, and 20 sex- and age-matched healthy controls under single- as well as easy and difficult dual-task conditions. Assessment of PD patients was performed during both the on- and off-drug phases. The results obtained during dual-task conditions reveal deficits in... 

    A new framework based on recurrence quantification analysis for epileptic seizure detection

    , Article IEEE Journal of Biomedical and Health Informatics ; Volume 17, Issue 3 , 2013 , Pages 572-578 ; 21682194 (ISSN) Niknazar, M ; Mousavi, S. R ; Vosoughi Vahdat, B ; Sayyah, M ; Sharif University of Technology
    This study presents applying recurrence quantification analysis (RQA) on EEG recordings and their subbands: delta, theta, alpha, beta, and gamma for epileptic seizure detection. RQA is adopted since it does not require assumptions about stationarity, length of signal, and noise. The decomposition of the original EEG into its five constituent subbands helps better identification of the dynamical system of EEG signal. This leads to better classification of the database into three groups: Healthy subjects, epileptic subjects during a seizure-free interval (Interictal) and epileptic subjects during a seizure course (Ictal). The proposed algorithm is applied to an epileptic EEG dataset provided... 

    A multi-scale model for determining the effects of pathophysiology and metabolic disorders on tumor growth

    , Article Scientific Reports ; Volume 10, Issue 1 , 20 February , 2020 Nikmaneshi, M. R ; Firoozabadi, B ; Mozafari, A ; Munn, L. L ; Sharif University of Technology
    Nature Research  2020
    The search for efficient chemotherapy drugs and other anti-cancer treatments would benefit from a deeper understanding of the tumor microenvironment (TME) and its role in tumor progression. Because in vivo experimental methods are unable to isolate or control individual factors of the TME and in vitro models often do not include all the contributing factors, some questions are best addressed with systems biology mathematical models. In this work, we present a new fully-coupled, agent-based, multi-scale mathematical model of tumor growth, angiogenesis and metabolism that includes important aspects of the TME spanning subcellular-, cellular- and tissue-level scales. The mathematical model is... 

    A regenerative approach towards recovering the mechanical properties of degenerated intervertebral discs: Genipin and platelet-rich plasma therapies

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 231, Issue 2 , 2017 , Pages 127-137 ; 09544119 (ISSN) Nikkhoo, M ; Wang, J. L ; Abdollahi, M ; Hsu, Y. C ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
    SAGE Publications Ltd  2017
    Degenerative disc disease, associated with discrete structural changes in the peripheral annulus and vertebral endplate, is one of the most common pathological triggers of acute and chronic low back pain, significantly depreciating an individual's quality of life and instigating huge socioeconomic costs. Novel emerging therapeutic techniques are hence of great interest to both research and clinical communities alike. Exogenous crosslinking, such as Genipin, and platelet-rich plasma therapies have been recently demonstrated encouraging results for the repair and regeneration of degenerated discs, but there remains a knowledge gap regarding the quantitative degree of effectiveness and... 

    Studying the effect of kinematical pattern on the mechanical performance of paraplegic gait with reciprocating orthosis

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 226, Issue 8 , 2012 , Pages 600-611 ; 09544119 (ISSN) Nakhaee, K ; Farahmand, F ; Salarieh, H ; Sharif University of Technology
    SAGE  2012
    Paraplegic users of mechanical walking orthoses, e.g. advanced reciprocating gait orthosis (ARGO), often face high energy expenditure and extreme upper body loading during locomotion. We studied the effect of kinematical pattern on the mechanical performance of paraplegic locomotion, in search for an improved gait pattern that leads to lower muscular efforts. A three-dimensional, four segment, six-degrees-of-freedom skeletal model of the advanced reciprocating gait orthosis-assisted paraplegic locomotion was developed based on the data acquired from an experimental study on a single subject. The effect of muscles was represented by ideal joint torque generators. A response surface analysis... 

    Translation and validation study of the Persian version of the Arthritis Impact Measurement Scales 2 (AIMS2) in patients with osteoarthritis of the knee

    , Article BMC Musculoskeletal Disorders ; Volume 10, Issue 1 , 2009 ; 14712474 (ISSN) Mousavi, S. J ; Parnianpour, M ; Askary Ashtiani, A. R ; Hadian, M. R ; Rostamian, A ; Montazeri, A ; Sharif University of Technology
    Background. The Arthritis Impact Measurement Scales 2 (AIMS2) has not been translated and validated for Persian-speaking patients with osteoarthritis of the knee. This was to provide a validated instrument to measure functional disability and health-related quality of life in patients with osteoarthritis of the knee in Iran. The aim of this study was to culturally adapt and validate the AIMS2 for Persian-speaking patients with osteoarthritis of the knee in Iran. Methods. A consecutive sample of patients with knee osteoarthritis were asked to complete the AIMS2, the Short Form Health Survey (SF-36) and four visual analog scales for pain, joint stiffness, patient's and physician's global... 

    The effect of angle and level of exertion on trunk neuromuscular performance during multidirectional isometric activities

    , Article Spine ; Volume 34, Issue 5 , 2009 , Pages E170-E177 ; 03622436 (ISSN) Mousavi, J ; Olyaei, G. R ; Talebian, S ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
    STUDY DESIGN.: To quantify trunk muscle capability and controllability in different angles and levels of isometric exertion using a torque tracking system. OBJECTIVE.: To investigate the effect of biaxial isometric exertions on the maximum capability of trunk and to examine the effect of angle and level of isometric exertion on trunk controllability during the tracking task in upright posture. SUMMARY OF BACKGROUND DATA.: Combined motions of trunk at varying exertion levels occur in most daily and occupational activities and are important risk factors of low back pain. Few studies have investigated trunk capability and controllability during multidirectional activities with different... 

    Trunk coordination in healthy and chronic nonspecific low back pain subjects during repetitive flexion-extension tasks: Effects of movement asymmetry, velocity and load

    , Article Human Movement Science ; Volume 45 , 2016 , Pages 182-192 ; 01679457 (ISSN) Mokhtarinia, H. R ; Sanjari, M. A ; Chehrehrazi, M ; Kahrizi, S ; Parnianpour, M ; Sharif University of Technology
    Multiple joint interactions are critical to produce stable coordinated movements and can be influenced by low back pain and task conditions. Inter-segmental coordination pattern and variability were assessed in subjects with and without chronic nonspecific low back pain (CNSLBP). Kinematic data were collected from 22 CNSLBP and 22 healthy volunteers during repeated trunk flexion-extension in various conditions of symmetry, velocity, and loading; each at two levels. Sagittal plane angular data were time normalized and used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify lumbar-pelvis and... 

    The potential role of auditory prediction error in decompensated tinnitus: An auditory mismatch negativity study

    , Article Brain and Behavior ; Volume 9, Issue 4 , 2019 ; 21623279 (ISSN) Mohebbi, M ; Daneshi, A ; Asadpour, A ; Mohsen, S ; Farhadi, M ; Mahmoudian, S ; Sharif University of Technology
    John Wiley and Sons Ltd  2019
    Introduction: Some tinnitus subjects habituate to their tinnitus but some others do not and complain of its annoyance tremendously. Normal sensory memory and change detection processes are needed for detecting the tinnitus signal as a prediction error and habituation to tinnitus. The purpose of this study was to compare auditory mismatch negativity as the index of sensory memory and change detection among the studied groups to search for the factors involving in the perception of tinnitus and preventing habituation in decompensated tinnitus subjects. Methods: Electroencephalography was recorded from scalp electrodes in compensated tinnitus, decompensated tinnitus, and no tinnitus control...