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Academic literature on the topic 'Noninvasive matrice'

Author: Grafiati
Published: 9 March 2023
Last updated: 10 March 2023

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Journal articles on the topic "Noninvasive matrice"

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Yu, Hong Xia, and Chuang Li. "Nonintrusive Efficiency Estimation of Induction Motors Based on an Adaptive Extended Kalman Filter." Applied Mechanics and Materials 446-447 (November 2013): 698–703. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.698.

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In this paper, a new nonintrusive efficiency estimation method without using stray loss approximation value was presented, the efficiency of induction motor was computed using estimated value of speed and load torque by AEKF. In AEKF, the speed and load torque as the state of system are estimated, the noise covariance matrices are estimated adaptively while the state of induction motor system are estimated to overcome the defect that estimation results are affected by the selected noise covariance matrices in EKF, then the estimated speed and the load torque are used to achieve noninvasive efficiency estimation. Experimental results demonstrate that the efficiency estimation results of this method has higher accuracy and are not affected by initial value of noises covariance matrices.
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Pfeifer, B., M. Seger, C. Hintermüller, F. Hanser, R. Modre, B. Tilg, T. Trieb, et al. "Computationally Efficient Noninvasive Cardiac Activation Time Imaging." Methods of Information in Medicine 44, no. 05 (2005): 674–86. http://dx.doi.org/10.1055/s-0038-1634024.

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Summary Objective: The computer model-based computation of the cardiac activation sequence in humans has been recently subject of successful clinical validation. This method is of potential interest for guiding ablation therapy of arrhythmogenic substrates. However, computation times of almost an hour are unattractive in a clinical setting. Thus, the objective is the development of a method which performs the computation in a few minutes run time. Methods: The computationally most expensive part is the product of the lead field matrix with a matrix containing the source pattern on the cardiac surface. The particular biophysical properties of both matrices are used for speeding up this operation by more than an order of magnitude. A conjugate gradient optimizer was developed using C++ for computing the activation map. Results: The software was tested on synthetic and clinical data. The increase in speed with respect to the previously used Fortran 77 implementation was a factor of 30 at a comparable quality of the results. As an additional finding the coupled regularization strategy, originally introduced for saving computation time, also reduced the sensitivity of the method to the choice of the regularization parameter. Conclusions: As it was shown for data from a WPW-patient the developed software can deliver diagnostically valuable information at a much shorter span of time than current clinical routine methods. Its main application could be the localization of focal arrhythmogenic substrates.
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Oleszko-Torbus, Natalia, Marcelina Bochenek, Alicja Utrata-Wesołek, Agnieszka Kowalczuk, Andrzej Marcinkowski, Andrzej Dworak, Agnieszka Fus-Kujawa, Aleksander L. Sieroń, and Wojciech Wałach. "Poly(2-oxazoline) Matrices with Temperature-Dependent Solubility—Interactions with Water and Use for Cell Culture." Materials 13, no. 12 (June 13, 2020): 2702. http://dx.doi.org/10.3390/ma13122702.

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In this work, we studied the stability of matrices with temperature-dependent solubility and their interactions with water at physiological temperature for their application in cell culture in vitro. Gradient copolymers of 2-isopropyl- with 2-n-propyl-2-oxazoline (P(iPrOx-nPrOx)) were used to prepare the matrices. The comonomer ratio during polymerization was chosen such that the cloud point temperature (TCP) of the copolymer was below 37 °C while the glass transition (Tg) was above 37 °C. The role of the support for matrices in the context of their stability in aqueous solution was examined. Therefore, matrices in the form of both self-supported bulk polymer materials (fibrillar mats and molds) and polymer films supported on the silica slides were examined. All of the matrices remained undissolved when incubated in water at a temperature above TCP. For the self-supported mats and molds, we observed the loss of shape stability, but, in the case of films supported on silica slides, only slight changes in morphology were observed. For a more in-depth investigation of the origin of the shape deformation of self-supported matrices, we analyzed the wettability, thickness, and water uptake of films on silica support because the matrices remained undeformed under these conditions. It was found that, above the TCP of P(iPrOx-nPrOx), the wettability of the films decreased, but at the same time the films absorbed water and swelled. We examined how this specific behavior of the supported films influenced the culture of fibroblasts. The temperature-dependent solubility of the matrices and the possibility of noninvasive cell separation were also examined.
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Tickle, Jacqueline A., Harish Poptani, Arthur Taylor, and Divya M. Chari. "Noninvasive imaging of nanoparticle-labeled transplant populations within polymer matrices for neural cell therapy." Nanomedicine 13, no. 11 (June 2018): 1333–48. http://dx.doi.org/10.2217/nnm-2017-0347.

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Lin, Shuyu, Wenzhuo Yu, Bo Wang, Yichao Zhao, Ke En, Jialun Zhu, Xuanbing Cheng, et al. "Noninvasive wearable electroactive pharmaceutical monitoring for personalized therapeutics." Proceedings of the National Academy of Sciences 117, no. 32 (July 27, 2020): 19017–25. http://dx.doi.org/10.1073/pnas.2009979117.

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To achieve the mission of personalized medicine, centering on delivering the right drug to the right patient at the right dose, therapeutic drug monitoring solutions are necessary. In that regard, wearable biosensing technologies, capable of tracking drug pharmacokinetics in noninvasively retrievable biofluids (e.g., sweat), play a critical role, because they can be deployed at a large scale to monitor the individuals’ drug transcourse profiles (semi)continuously and longitudinally. To this end, voltammetry-based sensing modalities are suitable, as in principle they can detect and quantify electroactive drugs on the basis of the target’s redox signature. However, the target’s redox signature in complex biofluid matrices can be confounded by the immediate biofouling effects and distorted/buried by the interfering voltammetric responses of endogenous electroactive species. Here, we devise a wearable voltammetric sensor development strategy—centering on engineering the molecule–surface interactions—to simultaneously mitigate biofouling and create an “undistorted potential window” within which the target drug’s voltammetric response is dominant and interference is eliminated. To inform its clinical utility, our strategy was adopted to track the temporal profile of circulating acetaminophen (a widely used analgesic and antipyretic) in saliva and sweat, using a surface-modified boron-doped diamond sensing interface (cross-validated with laboratory-based assays,R2∼ 0.94). Through integration of the engineered sensing interface within a custom-developed smartwatch, and augmentation with a dedicated analytical framework (for redox peak extraction), we realized a wearable solution to seamlessly render drug readouts with minute-level temporal resolution. Leveraging this solution, we demonstrated the pharmacokinetic correlation and significance of sweat readings.
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Turlewicz-Podbielska, Hanna, Jan Włodarek, and Małgorzata Pomorska-Mól. "Noninvasive strategies for surveillance of swine viral diseases: a review." Journal of Veterinary Diagnostic Investigation 32, no. 4 (July 2020): 503–12. http://dx.doi.org/10.1177/1040638720936616.

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In view of the intensive development of the swine industry, monitoring and surveillance of infectious diseases require low-cost, effective, and representative population sampling methods. We present herein the state of knowledge, to date, in the use of alternative strategies in the monitoring of swine health. Blood sampling, the most commonly used method in veterinary medicine to obtain samples for monitoring swine health, is labor-intensive and expensive, which has resulted in a search for alternative sampling strategies. Oral fluid (OF) is a good alternative to serum for pooled sample analysis, especially for low-prevalence pathogens. Detection of viral nucleic acids or antiviral antibodies in OF is used to detect numerous viruses in the swine population. Meat juice is used as an alternative to serum in serologic testing. Processing fluid obtained during processing of piglets (castration and tail-docking) may also be used to detect viruses. These matrices are simple, safe, cost-effective, and allow testing of many individuals at the same time. The latest methods, such as snout swabs and udder skin wipes, are also promising. These alternative samples are easy to acquire, and do not affect animal welfare negatively.
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Artioli, Gilberto, and Daniel S. Hussey. "Imaging with Neutrons." Elements 17, no. 3 (June 1, 2021): 189–94. http://dx.doi.org/10.2138/gselements.17.3.189.

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By exploiting the penetration, attenuation, and scattering properties of neutrons, images of matter in two or three dimensions reveal information unobtainable using other probes. Despite the limitation in brilliance of neutron sources, several neutron-based imaging techniques are essential to different aspects of modern geoscience. Typical examples include the evaluation of porosity in rocks and sediments, mapping of light elements in solids, noninvasive probing of cultural heritage objects, investigations of thick engineering components, and the exploration of diffusion and percolation processes of fluids within porous matrices, organo-inorganic composites, and living organisms. Techniques under development include simultaneous neutron and X-ray tomography in heterogeneous media, Bragg-edge imaging, and the possibility of porosimetry from dark-field imaging.
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Mitrea, Delia, Paulina Mitrea, Sergiu Nedevschi, Radu Badea, Monica Lupsor, Mihai Socaciu, Adela Golea, Claudia Hagiu, and Lidia Ciobanu. "Abdominal Tumor Characterization and Recognition Using Superior-Order Cooccurrence Matrices, Based on Ultrasound Images." Computational and Mathematical Methods in Medicine 2012 (2012): 1–17. http://dx.doi.org/10.1155/2012/348135.

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The noninvasive diagnosis of the malignant tumors is an important issue in research nowadays. Our purpose is to elaborate computerized, texture-based methods for performing computer-aided characterization and automatic diagnosis of these tumors, using only the information from ultrasound images. In this paper, we considered some of the most frequent abdominal malignant tumors: the hepatocellular carcinoma and the colonic tumors. We compared these structures with the benign tumors and with other visually similar diseases. Besides the textural features that proved in our previous research to be useful in the characterization and recognition of the malignant tumors, we improved our method by using the grey level cooccurrence matrix and the edge orientation cooccurrence matrix of superior order. As resulted from our experiments, the new textural features increased the malignant tumor classification performance, also revealing visual and physical properties of these structures that emphasized the complex, chaotic structure of the corresponding tissue.
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Lamoureux, M. M., J. C. Hutton, D. L. Styris, and R. L. Gordon. "Noninvasive Quantitative Chromium(III) Speciation in Neat Solid Mixtures by Extended X-ray Absorption Fine Structure Spectroscopy." Applied Spectroscopy 49, no. 6 (June 1995): 808–12. http://dx.doi.org/10.1366/0003702953964471.

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A procedure that uses extended X-ray absorption fine structure (EXAFS) spectroscopy for quantitative chromium(III) speciation in neat solid mixtures is described. The procedure uses the full, filtered EXAFS, e.g., 4 ≤ k ≤ 12 Å−1, rather than the smaller k-range associated with a single coordination sphere. Concentration is determined by a simple correlation of full, filtered EXAFS of standards with full, filtered EXAFS of mixtures. Under optimized conditions, calibration curves for mixtures of Cr2O3 and Cr(NO3)3·9H2O have slopes of 1.002, respective intercepts of −0.7% and 0.5%, and correlation coefficients of 0.9991. Fluorescence EXAFS from mixtures must be compared to fluorescence EXAFS from standards, and the matrices and thicknesses of standards and mixtures must be closely matched. Transmission EXAFS of standards must be obtained to correct for self-absorption effects.
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Vivaldi, F., A. Dallinger, N. Poma, A. Bonini, D. Biagini, P. Salvo, F. Borghi, A. Tavanti, F. Greco, and F. Di Francesco. "Sweat analysis with a wearable sensing platform based on laser-induced graphene." APL Bioengineering 6, no. 3 (September 1, 2022): 036104. http://dx.doi.org/10.1063/5.0093301.

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The scientific community has shown increasing interest in laser scribing for the direct fabrication of conductive graphene-based tracks on different substrates. This can enable novel routes for the noninvasive analysis of biofluids (such as sweat or other noninvasive matrices), whose results can provide the rapid evaluation of a person's health status. Here, we present a wearable sensing platform based on laser induced graphene (LIG) porous electrodes scribed on a flexible polyimide sheet, which samples sweat through a paper sampler. The device is fully laser manufactured and features a two layer design with LIG-based vertical interconnect accesses. A detailed characterization of the LIG electrodes including pore size, surface groups, surface area in comparison to electroactive surface area, and the reduction behavior of different LIG types was performed. The bare LIG electrodes can detect the electrochemical oxidation of both uric acid and tyrosine. Further modification of the surface of the LIG working electrode with an indoaniline derivative [4-((4-aminophenyl)imino)-2,6-dimethoxycyclohexa-2,5-dien-1-one] enables the voltammetric measurement of pH with an almost ideal sensitivity and without interference from other analytes. Finally, electrochemical impedance spectroscopy was used to measure the concentrations of ions through the analysis of the sweat impedance. The device was successfully tested in a real case scenario, worn on the skin during a sports session. In vitro tests proved the non-cytotoxic effect of the device on the A549 cell line.
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Dissertations / Theses on the topic "Noninvasive matrice"

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FUSI, JASMINE. "REPRODUCTION AND PERINATOLOGY IN COMPANION ANIMALS INVESTIGATED BY USE OF NONINVASIVE MATRICES." Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/809893.

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Reproduction in companion animals is a topic of growing interest for scientific research, but knowledge about some aspects is still lacking. This is likely due to the need of collecting a large number of serial samples in order to perform longitudinal studies of the longer-lasting reproductive phases, which is now incompatible with the current concept of animal welfare, according to which any distress must be avoided, especially where pregnant and neonatal subjects are concerned. For these reasons, complying with the need of respecting animal welfare and aiming to study reproductive phases that are still incompletely explored in companion animals, the project lines of the present PhD thesis were focused on three crucial phases of reproduction: pregnancy and post-partum, perinatology and puberty. This was achieved by using matrices, like coat and the claws, and, to a lesser extent, fetal fluids obtained by noninvasive sampling. The sudden Covid-19 pandemic and the consequent lockdown rules have partially impaired the sample collection and laboratory analyses, but some interesting and satisfactory data were provided nonetheless. In the pregnancy and post-partum study, the results showed changes in the concentrations of cortisol (C) in coat from mating to 60 days post- partum, in line with what was reported for cats, suggesting that canine maternity could be considered as a challenge for the bitches, and dehydroepiandrosterone-sulfate DHEA(S) was also analyzed. About perinatology, the claws concentrations of C, DHEA(S), E2 and T tended to decrease from birth until 60 days of age, adding precious information about the perinatal physiology. In fetal fluids, leptin amniotic concentrations were higher in smaller-seized breeds, highlighting the role of breed body-size in affecting the intrauterine fetal metabolism. In the puberty study, in cats 17β-estradiol (E2) and testosterone (T) concentrations were assessed in coat and dewclaws. The concentrations of T in coat significantly differed between pubertal males and females and between gonadectomized males and females. The concentrations of T in coat were higher in pubertal than prepubertal male cats. In dogs, the analyses of the concentrations of C, DHEA(S), T and E2 in coat showed lower DHEA(S) concentration in pubertal than prepubertal and gonadectomized female dogs. In males, T concentrations in coat were higher in pubertal than prepubertal dogs, and C concentrations in coat were higher in pubertal than prepubertal and gonadectomized dogs, suggesting that pubertal status leads to a higher activation of the HPA axis in male dogs. The results shown in the present thesis evidenced the usefulness of these matrices for longitudinal and long-term hormonal studies of reproduction in dogs and cats, providing useful data about crucial reproductive phases and new interesting insights. Further investigations are needed to better understand some pending questions about the use of these matrices.
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Li, Yanfang. "A study on the use of polarized light in application to noninvasive tissue diagnostics." University of Toledo / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1134596719.

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Book chapters on the topic "Noninvasive matrice"

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del Rosario Sánchez Valerio, María. "Current Diagnostic Tests for Dry Eye Disease in Sjögren’s Syndrome." In Eye Diseases - Recent Advances, New Perspectives and Therapeutic Options [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103671.

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Sjogren’s syndrome (Sicca Syndrome) is mainly characterized by the presence of dry eye disease (DED). The diagnosis of DED in patients with Sjogren’s syndrome has been limited to tests such as the Schirmer test, tear breakup time (TBUT), and corneal stains; however, currently we can evaluate the functional unit in detail lacrimal, which is affected in patients with dry eye and Sjögren’s syndrome; thanks to technology that provides objective details for this difficult diagnostic. The newer evaluations that provide the greatest diagnostic value for Sjogren’s syndrome are: noninvasive keratograph tear rupture time (NIKBUT), tear meniscus height (TMH), Schirmer’s test, meibography, ocular surface disease index (OSDI), Vital stains of the ocular surface, Matrix Metalloproteinase 9 (MMP-9), Tear osmolarity (TearLab); all of these are important complements to the existing tests, which, although less objective, are not substitutable.
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Conference papers on the topic "Noninvasive matrice"

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Barbur, J. L., J. Birch, and A. J. Harlow. "Threshold and Suprathreshold Responses to Chromatic Stimuli Using Psychophysical and Pupillometeric Methods." In Noninvasive Assessment of the Visual System. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/navs.1992.suc5.

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Colour difference thresholds reflect the sensitivity of the channels involved in chromatic discrimination and have been measured elegantly by MacAdam for several directions of modulation in the CIE (x,y) - chromaticity diagram from estimates of standard deviation associated with successive colour matches (MacAdam, 1942). The extent of isochromatic regions, formally associated with the direction of colour confusion lines (Pitt, 1935, Wright, 1952) can in principle be mapped out in colour discrimination experiments although in practice the luminance contrast of the test pattern as seen by colour deficient observers makes such measurements difficult to carry out. Mollon and Reffin (1989) have developed a test which overcomes largely these difficulties by following the techniques described by Stilling (Stilling, 1877) which are based on the relative insensitivity of the visual system when required to judge luminance differences between spatially discountinuous target elements, presented on a dark background field and varying randomly in luminance. We have extended this approach and eliminated the need to use a dark background field by developing a Random, spatiotemporal Luminance Masking (RLM) technique. The method employs a matrix of spatially discrete elements which form part of the uniform background field and are equal in time-averaged luminance to that of the background.
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Namani, Ravi, Matthew Wood, Shelly E. Sakiyama-Elbert, and Philip V. Bayly. "Anisotropic Mechanical Properties of Soft Tissues by Magnetic Resonance Elastography." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206290.

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Structure-function relationships incorporate anisotropy of soft tissues, to account for their direction-dependent loading response [1]. Empirical measures: fiber alignment and distribution have been used to describe soft tissue response due to cell-matrix interactions and applied loads [2, 3]. To complement these measures, noninvasive estimation of anisotropic mechanical properties is essential. Magnetic resonance elastography (MRE) is a noninvasive technique to obtain elastic properties form propagating shear waves [4]. Wave propagation patterns in MRE were found to vary with direction of tissue excitation and fiber orientation [5]. Accurate estimates of anisotropic elastic properties of soft tissues have yet to be obtained by MRE.
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Lee, Hack-Jin, Hakseung Kim, Dong-Ho Lee, Xiao ke Yang, Eun-Jin Jeong, Dae-Hyeon Park, Young-Tak Kim, and Dong-Joo Kim. "Noninvasive assessment of intracranial pressure using functional matrix estimation method." In 2015 3rd International Winter Conference on Brain-Computer Interface (BCI). IEEE, 2015. http://dx.doi.org/10.1109/iww-bci.2015.7073052.

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Nossal, Ralph. "Photon Migration in Biological Tissue." In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.mc4.

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In recent years considerable effort has been given to developing noninvasive diagnostic procedures which utilize light to penetrate optically turbid biological tissues. Among these are pulse oximetry1,2 and time-resolved absorption spectroscopy3–5 to assess regional blood oxygenation, laser Doppler techniques to measure peripheral blood flow,6 and imaging modalities to discern tumours or other tissue inhomogenities.7–9 These methods, which are directed towards the analysis of living tissues, rely upon photons which have migrated through a highly scattering tissue matrix before being re-emitted and detected at an accessible surface.
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Meo, Marianna, Vicente Zarzoso, Olivier Meste, Decebal G. Latcu, and Nadir Saoudi. "Nonnegative matrix factorization for noninvasive prediction of catheter ablation outcome in persistent atrial fibrillation." In ICASSP 2012 - 2012 IEEE International Conference on Acoustics, Speech and Signal Processing. IEEE, 2012. http://dx.doi.org/10.1109/icassp.2012.6287955.

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Novak, Tyler, Jamie Canter, Dafang Chen, Joel Hungate, Sherry Voytik-Harbin, and Corey Neu. "Magnetic Alignment of Type I Collagen as a Method for Altering Tensile Mechanical Properties." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80907.

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To date, ligament and tendon replacements largely utilize autograft/allograft transplantation, although the use of tissue engineered materials remain a promising solution [10]. The development of an engineered solution may depend on the choice of scaffold materials with optimal fiber alignment. Type I collagen is an abundant extracellular matrix component in musculoskeletal tissues. The controlled alignment of type I collagen for tissue engineering and regenerative medicine applications enables the fabrication of unique scaffolds that emulate the ultrastructure of their native counterparts. Moreover, the alignment of type I collagen has become a common technique to manipulate mechanical properties of tissue constructs and the biological response of embedded cells [1,2]. It is additionally important to develop noninvasive methods to align collagen structures while maintaining inherent structural integrity and biological activity.
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Ni, Qingwen, and Shuo Chen. "Assessing the Effect of Matrix Metalloproteinase-9 on the Growth of Mice Teeth." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53708.

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Dentin and bone are formed when odontoblasts and osteoblasts synthesize and secrete collagen type I-rich extracellular matrix that mineralizes in a highly controlled manner. A wide spectrum of mouse and human disorders affecting tooth and bone biomineralization shows that dentin and bone formation are under strict genetic control. Although the controlling mechanisms of dentinogenesis and osteogenesis require further study, a large body of evidence points to the importance of the matrix metalloproteinases (MMPs) participate in a wide variety of extracellular matrix degradation. Detailed knowledge of MMPs may be important for understanding the pathogenesis of tooth development. Some researchers have pointed MMP-9 is an extracelluar proteinase that is highly expressed in osteoclasts and has been postulated to play an important role in their resorptive activity. Although MMP-9 has been reported to play a role in bone resorption, the association of this enzyme during deciduous tooth resorption has not yet been clarified. Based on accumulating evidence, we hypothesized that MMP-9 should play a role in teeth attrition. In this study, we have applied NMR relaxation technique to assess age-related MMP-9 KO tooth quality in vitro by quantifying changes in dentin and pulp simultaneously. The major hypothesis in this paper was that whether noninvasive NMR relaxation time measurements could be used to characterize MMP-9 KO changes in dentin and pulp, and to predict tooth quality. Specifically, we tested that age-related MMP-9 KO tooth changes result in an alteration of the NMR spin-spin (T2) relaxation time signal due to the structural changes in the tooth matrix. This signal can be further processed to produce a T2 relaxation distribution spectrum related to dentin and pulp, and their derived parameters can be used as descriptors of age-related MMP-9 KO tooth changes. In this study, the proton liquid-like NMR spin-spin (T2) relaxation decay signal was obtained from the Carr-Purcell-Meiboom-Gill (CPMG) NMR spin echo train method [1,2], then the relaxation decay signal was converted to T2 relaxation distribution spectra describing the size domain of dentin and pulp. Therefore, we can calibrate the intensities in NMR inversion T2 relaxation distribution spectra corresponding to the amount of dentin and pulp related to the structural changes. Here, we propose an NMR calibration method “NMR standard estimation” — the ratio of the amount of pulp to the amount of dentin obtained from NMR T2 distribution spectra that can be used to measure the age-related MMP-9 KO structural changes in teeth [3]. We are cognizant of the biological and physiological variability manifest in teeth size variations, but feel that this kind of NMR standard estimation — the ratio of amount of dentin to amount of pulp from the NMR T2 inversion spectrum can be used to determine age-related MMP-9 KO structural changes in teeth and eliminate any variations in size of teeth.
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Gonzales, Silvia D., Chong Wang, Amaris A. Genemaras, and C. Y. Charles Huang. "Novel Measuring System of ATP-Induced Transmembrane Potential Change of Nucleus Pulposus Cells." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80539.

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Low back pain is a serious concern in industrialized societies that affects millions of people around the world [1]. It can be attributed to several spine disorders; intervertebral disc (IVD) degeneration being one of the most common causes [2]. IVDs are the largest avascular tissue in the body and are composed of two differentiated anatomical structures: the nucleus pulposus (NP) and the annulus fibrosus (AF). The ability to withstand compressive loads due to weight and bending is provided by the swelling of the NP structure, while the ability to resist tensile forces during bending and twisting is provided by the AF fibers [3]. The biomechanical functions of NP and AF rely on their extracellular matrix (ECM) structure and composition. Previous studies have demonstrated that static and dynamic compressive loading alters ATP production, which may have an effect on ECM synthesis [2]. In addition, dynamic loading has shown an increase in ATP release from NP cells, which may contribute to endplate calcification and therefore to IVD degeneration [2, 4]. When tissue is damaged, ATP, which is found in millimolar concentrations in all cells, leaks or is released into the extracellular milieu [5, 6]. Extracellular ATP is a powerful signaling molecule that can regulate cell metabolism, survival, and growth [7]. However, IVD cell response to ATP has not been investigated. The receptors involved in transducing responses to ATP are found in many tissues throughout the body and are responsible for different kinds of intercellular communication. ATP receptor subtypes are ligand-gated ion channels (P2X) and G-protein coupled receptors (P2Y). P2X receptors show calcium permeability while P2Y receptors mediate calcium release from intracellular stores in response to ATP [6]. Direct ATP application to the cell has been reported to cause a change in membrane conductance in a variety of tissues [8]. The voltage sensitive dye di-8-ANEPPS allows for a noninvasive method of measuring fluorescence changes of the cell membrane, which are proportional to variations of the transmembrane potential [8]. Therefore, the objectives of this study were (1) to develop a novel transmembrane potential measuring system using di-8-ANEPPS dye and (2) to investigate the response of NP cells to ATP by measuring the change in transmembrane potential.
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