Browsing by Subject "Biomedical engineering"
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Item A neurotechnological aid for semi-autonomous suction in robotic-assisted surgery(Springer, 2022-03-16) Barragan, Juan Antonio; Yang, Jing; Yu, Denny; Wachs, Juan P.; Surgery, School of MedicineAdoption of robotic-assisted surgery has steadily increased as it improves the surgeon’s dexterity and visualization. Despite these advantages, the success of a robotic procedure is highly dependent on the availability of a proficient surgical assistant that can collaborate with the surgeon. With the introduction of novel medical devices, the surgeon has taken over some of the surgical assistant’s tasks to increase their independence. This, however, has also resulted in surgeons experiencing higher levels of cognitive demands that can lead to reduced performance. In this work, we proposed a neurotechnology-based semi-autonomous assistant to release the main surgeon of the additional cognitive demands of a critical support task: blood suction. To create a more synergistic collaboration between the surgeon and the robotic assistant, a real-time cognitive workload assessment system based on EEG signals and eye-tracking was introduced. A computational experiment demonstrates that cognitive workload can be effectively detected with an 80% accuracy. Then, we show how the surgical performance can be improved by using the neurotechnological autonomous assistant as a close feedback loop to prevent states of high cognitive demands. Our findings highlight the potential of utilizing real-time cognitive workload assessments to improve the collaboration between an autonomous algorithm and the surgeon.Item Computational Methods and Models in Circulatory and Reproductive Systems(Hindawi, 2016) Tian, Fang-Bao; Sui, Yi; Zhu, Luoding; Shu, Chang; Sung, Hyung J.; Department of Mathematical Sciences, School of ScienceItem Developing a Neural Signal Processor Using the Extended Analog Computer(2013-08-21) Soliman, Muller Mark; Yoshida, Ken; Eberhart, Russell C.; Mills, Jonathan W. (Jonathan Wayne); Berbari, Edward J.Neural signal processing to decode neural activity has been an active research area in the last few decades. The next generation of advanced multi-electrode neuroprosthetic devices aim to detect a multiplicity of channels from multiple electrodes, making the relatively time-critical processing problem massively parallel and pushing the computational demands beyond the limits of current embedded digital signal processing (DSP) techniques. To overcome these limitations, a new hybrid computational technique was explored, the Extended Analog Computer (EAC). The EAC is a digitally confgurable analog computer that takes advantage of the intrinsic ability of manifolds to solve partial diferential equations (PDEs). They are extremely fast, require little power, and have great potential for mobile computing applications. In this thesis, the EAC architecture and the mechanism of the formation of potential/current manifolds was derived and analyzed to capture its theoretical mode of operation. A new mode of operation, resistance mode, was developed and a method was devised to sample temporal data and allow their use on the EAC. The method was validated by demonstration of the device solving linear diferential equations and linear functions, and implementing arbitrary finite impulse response (FIR) and infinite impulse response (IIR) linear flters. These results were compared to conventional DSP results. A practical application to the neural computing task was further demonstrated by implementing a matched filter with the EAC simulator and the physical prototype to detect single fiber action potential from multiunit data streams derived from recorded raw electroneurograms. Exclusion error (type 1 error) and inclusion error (type 2 error) were calculated to evaluate the detection rate of the matched filter implemented on the EAC. The detection rates were found to be statistically equivalent to that from DSP simulations with exclusion and inclusion errors at 0% and 1%, respectively.Item Effects of Collagen Gel Stiffness on Cdc42 Activities of Endothelial Colony Forming Cells during Early Vacuole Formation(2013-08-14) Kim, Seung Joon; Na, Sungsoo; Xie, Dong; Li, JiliangRecent preclinical reports have provided evidence that endothelial colony forming cells (ECFCs), a subset of endothelial progenitor cells, significantly improve vessel formation, largely due to their robust vasculogenic potential. While it has been known that the Rho family GTPase Cdc42 is involved in this ECFC-driven vessel formation process, the effect of extracellular matrix (ECM) stiffness on its activity during vessel formation is largely unknown. Using a fluorescence resonance energy transfer (FRET)-based Cdc42 biosensor, we examined the spatio-temporal activity of Cdc42 of ECFCs in three-dimensional (3D) collagen matrices with varying stiffness. The result revealed that ECFCs exhibited an increase in Cdc42 activity in a soft (150 Pa) matrix, while they were much less responsive in a rigid (1 kPa) matrix. In both soft and rigid matrices, Cdc42 was highly activated near vacuoles. However, its activity is higher in a soft matrix than that in a rigid matrix. The observed Cdc42 activity was closely associated with vacuole formation. Soft matrices induced higher Cdc42 activity and faster vacuole formation than rigid matrices. However, vacuole area is not dependent on the stiffness of matrices. Time courses of Cdc42 activity and vacuole formation data revealed that Cdc42 activity proceeds vacuole formation. Collectively, these results suggest that matrix stiffness is critical in regulating Cdc42 activity in ECFCs and its activation is an important step in early vacuole formation.Item Electro-Quasistatic Animal Body Communication for Untethered Rodent Biopotential Recording(Springer Nature, 2021-02-08) Sriram, Shreeya; Avlani, Shitij; Ward, Matthew P.; Sen, Shreyas; Medicine, School of MedicineContinuous multi-channel monitoring of biopotential signals is vital in understanding the body as a whole, facilitating accurate models and predictions in neural research. The current state of the art in wireless technologies for untethered biopotential recordings rely on radiative electromagnetic (EM) fields. In such transmissions, only a small fraction of this energy is received since the EM fields are widely radiated resulting in lossy inefficient systems. Using the body as a communication medium (similar to a ’wire’) allows for the containment of the energy within the body, yielding order(s) of magnitude lower energy than radiative EM communication. In this work, we introduce Animal Body Communication (ABC), which utilizes the concept of using the body as a medium into the domain of untethered animal biopotential recording. This work, for the first time, develops the theory and models for animal body communication circuitry and channel loss. Using this theoretical model, a sub-inch3 [1″ × 1″ × 0.4″], custom-designed sensor node is built using off the shelf components which is capable of sensing and transmitting biopotential signals, through the body of the rat at significantly lower powers compared to traditional wireless transmissions. In-vivo experimental analysis proves that ABC successfully transmits acquired electrocardiogram (EKG) signals through the body with correlation >99% when compared to traditional wireless communication modalities, with a 50× reduction in power consumption.Item Exploring arterial tissue microstructural organization using non-Gaussian diffusion magnetic resonance schemes(Springer Nature, 2021-11-15) Shahid, Syed Salman; Johnston, Robert D.; Smekens, Celine; Kerskens, Christian; Gaul, Robert; Tornifoglio, Brooke; Stone, Alan J.; Lally, Caitríona; Radiology and Imaging Sciences, School of MedicineThe purpose of this study was to characterize the alterations in microstructural organization of arterial tissue using higher-order diffusion magnetic resonance schemes. Three porcine carotid artery models namely; native, collagenase treated and decellularized, were used to estimate the contribution of collagen and smooth muscle cells (SMC) on diffusion signal attenuation using gaussian and non-gaussian schemes. The samples were imaged in a 7 T preclinical scanner. High spatial and angular resolution diffusion weighted images (DWIs) were acquired using two multi-shell (max b-value = 3000 s/mm2) acquisition protocols. The processed DWIs were fitted using monoexponential, stretched-exponential, kurtosis and bi-exponential schemes. Directionally variant and invariant microstructural parametric maps of the three artery models were obtained from the diffusion schemes. The parametric maps were used to assess the sensitivity of each diffusion scheme to collagen and SMC composition in arterial microstructural environment. The inter-model comparison showed significant differences across the considered models. The bi-exponential scheme based slow diffusion compartment (Ds) was highest in the absence of collagen, compared to native and decellularized microenvironments. In intra-model comparison, kurtosis along the radial direction was the highest. Overall, the results of this study demonstrate the efficacy of higher order dMRI schemes in mapping constituent specific alterations in arterial microstructure.Item Exploring Chondrocyte Integrin Regulation of Growth Factor IGF-I Expression from a Transient pAAV Vector(2013-08-20) Ratley, Samantha Kay; Trippel, Stephen B.; Lin, Chien-Chi; Stocum, David L.Insulin-like Growth Factor I (IGF-I) is a growth factor that stimulates both mitogenic and anabolic responses in articular chondrocytes. While it has been shown that exogenous IGF-I can regulate chondrocyte integrins, little is known regarding regulatory effects of IGF-I produced from a transiently expressed plasmid based adeno-associated virus (pAAV) vector. Because chondrocytes are using cellular machinery to overexpress IGF-I, it is of interest to see whether or not pAAV IGF-I will significantly upregulate or downregulate chondrocyte integrins. Additionally, it is of interest to know whether chondrocyte adhesion through integrins will have any regulatory effects on the production of IGF-I from the transgene. Therefore, this study will ascertain if pAAV IGF-I will have similar effects that exogenous IGF-I has on integrin regulation and if integrin silencing mechanisms will affect the production of IGF-I from the transgene. To test these hypotheses, adult articular chondrocytes were doubly transfected with the pAAV vector for IGF-I and short interference ribonucleic acid (siRNA) for integrins beta 1 and alpha V. Gene products were monitored at the transcriptional levels using quantitative real time polymerase chain reactions (qPCR) and IGF-I protein production was monitored at the translational level using enzyme linked immunoabsorbant assays (ELISAs). Adult articular chondrocytes doubly transfected were encapsulated in a three dimensional hydrogel system to simulate an in vivo environment. Samples were collected for analysis at days 2, 4, and 6 post encapsulation. Results show that IGF-I treatment with the pAAV vector does not cause significant changes in the transcriptional regulation of the beta 1 integrin in a three dimensional hydrogel system. The pAAV IGF-I vector did not cause significant regulatory changes on integrin alpha V at any time point during the experiment. Additionally, by knocking down the expression levels of integrins by using siRNA, it was shown that integrin knockdown does not have a significant regulatory effect on transcriptional or translational expression levels of IGF-I from the pAAV vector.Item In-situ cryo-immune engineering of tumor microenvironment with cold-responsive nanotechnology for cancer immunotherapy(Springer Nature, 2023-01-24) Ou, Wenquan; Stewart, Samantha; White, Alisa; Kwizera, Elyahb A.; Xu, Jiangsheng; Fang, Yuanzhang; Shamul, James G.; Xie, Changqing; Nurudeen, Suliat; Tirada, Nikki P.; Lu, Xiongbin; Tkaczuk, Katherine H. R.; He, Xiaoming; Medical and Molecular Genetics, School of MedicineCancer immunotherapy that deploys the host’s immune system to recognize and attack tumors, is a promising strategy for cancer treatment. However, its efficacy is greatly restricted by the immunosuppressive (i.e., immunologically cold) tumor microenvironment (TME). Here, we report an in-situ cryo-immune engineering (ICIE) strategy for turning the TME from immunologically “cold” into “hot”. In particular, after the ICIE treatment, the ratio of the CD8+ cytotoxic T cells to the immunosuppressive regulatory T cells is increased by more than 100 times in not only the primary tumors with cryosurgery but also distant tumors without freezing. This is achieved by combining cryosurgery that causes “frostbite” of tumor with cold-responsive nanoparticles that not only target tumor but also rapidly release both anticancer drug and PD-L1 silencing siRNA specifically into the cytosol upon cryosurgery. This ICIE treatment leads to potent immunogenic cell death, which promotes maturation of dendritic cells and activation of CD8+ cytotoxic T cells as well as memory T cells to kill not only primary but also distant/metastatic breast tumors in female mice (i.e., the abscopal effect). Collectively, ICIE may enable an efficient and durable way to leverage the immune system for combating cancer and its metastasis.Item An integrated sensor system for early fall detection(2013-05) Bandi, Ajay Kumar; Rizkalla, Maher E.; Salama, Paul; Kim, Dongsoo StephenPhysical activity monitoring using wearable sensors give valuable information about patient's neuro activities. Fall among ages of 60 and older in US is a leading cause for injury-related health issues and present serious concern in the public health care sector. If the emergency treatments are not on time, these injuries may result in disability, paralysis, or even death. In this work, we present an approach that early detect fall occurrences. Low power capacitive accelerometers incorporated with microcontroller processing units were utilized to early detect accurate information about fall events. Decision tree algorithms were implemented to set thresholds for data acquired from accelerometers. Data is then verified against their thresholds and the data acquisition decision unit makes the decision to save patients from fall occurrences. Daily activities are logged on an onboard memory chip with Bluetooth option to transfer the data wirelessly to mobile devices. In this work, a system prototype based on neurosignal activities was built and tested against seven different daily human activities for the sake of differentiating between fall and non-fall detection. The developed system features low power, high speed, and high reliability. Eventually, this study will lead to wearable fall detection system that serves important need within the health care sector. In this work Inter-Integrated Circuit (I2C) protocol is used to communicate between the accelerometers and the embedded control system. The data transfer from the Microcontroller unit to the mobile device or laptop is done using Bluetooth technology.Item Large-scale open-source three-dimensional growth curves for clinical facial assessment and objective description of facial dysmorphism(Springer Nature, 2021-06-09) Matthews, Harold S.; Palmer, Richard L.; Baynam, Gareth S.; Quarrell, Oliver W.; Klein, Ophir D.; Spritz, Richard A.; Hennekam, Raoul C.; Walsh, Susan; Shriver, Mark; Weinberg, Seth M.; Hallgrimsson, Benedikt; Hammond, Peter; Penington, Anthony J.; Peeters, Hilde; Claes, Peter D.; Biology, School of ScienceCraniofacial dysmorphism is associated with thousands of genetic and environmental disorders. Delineation of salient facial characteristics can guide clinicians towards a correct clinical diagnosis and understanding the pathogenesis of the disorder. Abnormal facial shape might require craniofacial surgical intervention, with the restoration of normal shape an important surgical outcome. Facial anthropometric growth curves or standards of single inter-landmark measurements have traditionally supported assessments of normal and abnormal facial shape, for both clinical and research applications. However, these fail to capture the full complexity of facial shape. With the increasing availability of 3D photographs, methods of assessment that take advantage of the rich information contained in such images are needed. In this article we derive and present open-source three-dimensional (3D) growth curves of the human face. These are sequences of age and sex-specific expected 3D facial shapes and statistical models of the variation around the expected shape, derived from 5443 3D images. We demonstrate the use of these growth curves for assessing patients and show that they identify normal and abnormal facial morphology independent from age-specific facial features. 3D growth curves can facilitate use of state-of-the-art 3D facial shape assessment by the broader clinical and biomedical research community. This advance in phenotype description will support clinical diagnosis and the understanding of disease pathogenesis including genotype–phenotype relations.