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Laminin-coated poly(L-lactide) filaments induce robust neurite growth while providing directional orientation

Journal of biomedical Materials Research Part B: Applied Biomaterials 2000年第4期51卷

作者： Nagarathnamma Rangappa Andres Romero Kevin D. Nelson Robert C. Eberhart George M. Smith Department of Anesthesiology and Pain Management University of Texas Southwestern Medical Center Dallas Texas 75235-9130 Joint Biomedical Engineering Program University of Texas Southwestern Medical Center Dallas Texas 75235-9130 and University of Texas at Arlington Arlington Texas 76019-0138

Cellular channels during development and after peripheral nerve injury are thought to provide guidance cues to growing axons. In tissue culture where these cues are absent, neurites from dorsal root ganglion neurons grow with a radial distribution. To induce directional axonal growth and to enhance the rate of axonal growth after injury, we have designed microfilaments of poly( L -lactide). We demonstrate that dorsal root ganglia grown on these filaments in vitro extend longitudinally oriented neurites in a manner similar to native peripheral nerves. The extent of neurite growth was significantly higher on laminin-coated filaments compared with uncoated and poly- L -lysine–coated filaments. As high as 5.8 ± 0.2 mm growth was observed on laminin-coated filaments compared with 2.0 ± 0.2 mm on uncoated and 2.2 ± 0.3 mm on poly- L -lysine–coated filaments within 8 days. Schwann cells were found to grow on all types of filaments. They were, however, absent in the leading edges of growth on laminin-coated filaments. Photolysis of Schwann cells caused a significant reduction in the neurite length on all types of filaments. Laminin-coated filaments, however, induced significantly longer neurites compared with uncoated and/or poly- L -lysine–coated filaments even in the absence of Schwann cells. Our results suggest that laminin-coated poly( L -lactide) filaments are suitable for inducing directional and enhanced axonal growth. Implants designed by arranging these microfilaments into bundles should aid regenerating axons by providing guidance cues and channels to organize matrix deposition, cell migration, axon growth, and improve functional recovery. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 51, 625–634, 2000.

关键词： PLLA filaments bioresorbable polymers dorsal root ganglia laminin PNS regeneration

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FIRST PASSAGE MEASUREMENTS OF DISPERSION COEFFICIENTS FOR SUSPENSION FLOWS

FIRST PASSAGE MEASUREMENTS OF DISPERSION COEFFICIENTS FOR SU...

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ASME 1999 International Mechanical engineering Congress and Exposition, IMECE 1999

作者： Eckstein, Eugene C. Leggas, Mark School of Biomedical Engineering Joint Program in BME University of Tennessee Memphis MemphisTN United States School of Biomedical Engineering Joint Program in BME University of Memphis MemphisTN United States

ISBN: (纸本)9780791816400

We report resuls of an experimental protocol for determining effective diffusion coefficients in suspension flows in thin channels. The method is based on the first-passage method (FPM), a well-known aspect of probability theory. Images of identifiable individual particles are collected at a regular rate by a video camera. The times needed for individual particles to move selected distances on either side of the original position are measured. Such events are individually the "first passage" for the selected net distances. Repeated evaluation of this statistic for the same initial conditions is done so that the history of axial motion can be summarized in a statistical manner. All images are collected in a moving frame of reference in order to limit more precisely the initial time and to make observations in a specified region of the flow. The protocol has been used in rectangular channels approximately 50 micrometers high and 500 micrometers wide to collect observations that were located approximately 12 microns in the narrow direction down from the upper surface. The local shear rate is estimated to be 100 inverse seconds. A dilute suspension of beads and a 25% suspension (volume/volume) of erythrocytes was used. Values that were measured compared well with those predicted by the Stokes-Einstein equation and with published data for blood flows. © 1999 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Suspensions (fluids)

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First passage measurements of dispersion coefficients for suspension flows

American Society of Mechanical Engineers, Bioengineering Div...

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American Society of Mechanical Engineers, Bioengineering Division (Publication) BED 1999年 43卷 57-58页

作者： Eckstein, Eugene C. Leggas, Mark School of Biomedical Engineering Joint Program in BME University of Tennessee Memphis Memphis TN United States School of Biomedical Engineering Joint Program in BME University of Tennessee Memphis TN United States

ISBN: (纸本)0791816400

We report results of an experimental protocol for determining effective diffusion coefficients in suspension flows in thin channels. The method is based on the first-passage method (FPM), a well-known aspect of probability theory. Images of identifiable individual particles are collected at a regular rate by a video camera. The times needed for individual particles to move selected distances on either side of the original position are measured. Such events are individually the 'first passage' for the selected net distances. Repeated evaluation of this statistic for the same initial conditions is done so that the history of axial motion can be summarized in a statistical manner. All images are collected in a moving frame of reference in order to limit more precisely the initial time and to make observations in a specified region of the flow. The protocol has been used in rectangular channels approximately 50 micrometers high and 500 micrometers wide to collect observations that were located approximately 12 microns in the narrow direction down from the upper surface. The local shear rate is estimated to be 100 inverse seconds. A dilute suspension of beads and a 25% suspension (volume/volume) of erythrocytes was used. Values that were measured compared well with those predicted by the Stokes-Einstein equation and with published data for blood flows.

关键词： Hemodynamics

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Rapid and slow potassium currents in a sinoatrial node cell model

Rapid and slow potassium currents in a sinoatrial node cell ...

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Computers in Cardiology (CinC)

作者： C.S. Oehmen S.S. Demir University of Tennessee Memphis USA Joint Graduate Program in Biomedical Engineering University of Memphis USA

The sinoatrial node (SAN) model of Demir et al. (Amer. J. Physiol, vol. 266, p. C832-52, 1994) was extended to include two potassium channels. A channel with fast and slow activation components and rapid inactivation (I/sub Kr/) and a channel with slow activation (I/sub Ks/) were investigated by Lei & Brown (1996) and Ono & Ito (1995). New K/sup +/ current descriptions were incorporated into the model. The simulated action potentials were in agreement with the action potentials recorded by Irasawa et al. (1993). The sum of I/sub Kr/ and I/sub Ks/ was comparable to the potassium delayed rectifier (I/sub K/) of Demir et al. with the exception that the sum did not totally inactivate. Simulations showed that I/sub Kr/ is essential for pacing, as seen in the experiments of Lei & Brown. Voltage clamp experiments were also accurately simulated. In conclusion, two distinct potassium channels were necessary to accurately simulate the K/sup +/ ionic mechanisms in the rabbit SAN cells.

关键词： Biomembranes Computational modeling Storage area networks Voltage Clamps Rabbits Calcium Delay Rectifiers Equations

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Platelet response to cardiopulmonary bypass studied by gamma scintigraphy and platelet aggregometry

Platelet response to cardiopulmonary bypass studied by gamma...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： J. Li R.C. Eberhart F.B. Harris B.P. Smith S. Rajasubramanian A. Pandit M.E. Jessen R. Chao A. Constantinescu Joint Biomedical Engineering Program University of Texas Southwestern Medical Center Dallas Dallas TX USA University of Texas at Dallas Richardson TX US

Platelet response to surface modified (SMA) Cobe Duo membrane oxygenators was evaluated in a pig model of cardiopulmonary bypass (CPB) by gamma scintigraphic imaging and platelet impedance aggregometry (PIA). Comparisons of platelet deposition, blood pool platelet counts and platelet aggregation were made between SMA coated CPB circuits and uncoated circuits. The SMA-coated oxygenators exhibited decreases in foreign surface induced platelet aggregation and platelet deposition.

关键词： Cardiology Blood Circuits Coatings biomedical measurements biomedical imaging Biomembranes Impedance Time measurement Adhesives

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A mixed gas sensor system based on thin film SAW sensor array and neural network 12

A mixed gas sensor system based on thin film SAW sensor arra...

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12th Southern biomedical engineering Conference, SBEC 1993

作者： Li, Jun Joint Biomedical Engineering Program University of Texas Southwestern Medical Center at Dallas University of Texas at Arlington United States

ISBN: (纸本)0780309766

A mixed gases (NOx and CO) measurement system based on surface acoustic wave (SAW) sensor array and neural network with continuous valued output style was developed. Sensor unit optimal designing sensor array and neural network construction were studied and the evaluation of the system was undertaken. This method could improve the precision of the measurement to 8% in the range of 0-30 p.p.M. © 1993 IEEE.

关键词： Acoustic waves

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A mixed gas sensor system based on thin film SAW sensor array and neural network

A mixed gas sensor system based on thin film SAW sensor arra...

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Southern biomedical engineering Conference

作者： Jun Li Joint Biomedical Engineering Program University of Texas Southwestern Medical Center Dallas USA

A mixed gases (NO/sub x/ and CO) measurement system based on surface acoustic wave (SAW) sensor array and neural network with continuous valued output style was developed. Sensor unit optimal designing sensor array and neural network construction were studied and the evaluation of the system was undertaken. This method could improve the precision of the measurement to 8% in the range of 0-30 p.p.M.< >

关键词： Sensor arrays Gas detectors Thin film sensors Surface acoustic waves Sensor systems Neural networks Acoustic sensors Acoustic measurements Gases Acoustic waves

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Noninvasive blood pressure measurements on the temporal artery 14

Noninvasive blood pressure measurements on the temporal arte...

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14th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBS 1992

作者： Von Maltzahn, Wolf W. Buckey, Jay Shenoy, Damodar Joint Biomedical Engineering Program University of Texas at Arlington University of Texas Southwestern Medical Center at Dallas United States

ISBN: (纸本)0780307852

Systolic and diastolic blood pressures were recorded noninvasively on the temporal artery and compared with systolic and diastolic blood pressures obtained from the brachial artery. Both types of measurements were based on the detection of Korotkoff sounds. Data was collected from five subjects with the subjects lying in a supine position, sitting at rest. and sitting immediately after moderate exercise. This comparative study showed that both pressure measurements track each other within a difference margin of ±10%. which is comparable to the generally accepted accuracy of noninvasive blood pressure measurements. © 1992 IEEE.

关键词： Pressure measurement

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Robust control of induced paralysis 14

Robust control of induced paralysis

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14th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBS 1992

作者： Behbehani, Khosrow Klein, Kevin W. Ramakrishna, Deepak Joint Biomedical Engineering Program University of Texas - Arlington University of Texas Southwestern Medical Center - Dallas United States Anesthesiology University of Texas Southwestern Medical School - Dallas United States

ISBN: (纸本)0780307852

Performance of an adaptive controller for automatic regulation of level of induced paralysis during surgery, using vecuronium bromide, is presented. In addition to adapting to variations in patient dynamic response parameters, the controller accommodates any variation in the pure time delays of the response. The performance results are obtained from a computer simulation of the nonlinear patients pharmacokinetic and pharmacodynamic response to the drug. © 1992 IEEE.

关键词： Robust control

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Noninvasive blood pressure measurements on the temporal artery

Noninvasive blood pressure measurements on the temporal arte...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Wolf W. von Mateahn Jay Buckey Damodar Shenoy Joint Biomedical Engineering Program University of Texas at Arlington and University of Texas Southwestern Medical Center at Dallas Southwestern Medical Center Dallas University of Texas Arlington USA

关键词： Extraterrestrial measurements Frequency measurement Pressure measurement Blood Arteries Position measurement Skin

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