Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.94514
J. Newell, D. Isaacson, D. Gisser, K. Cheng, J. Goble
The authors have designed, built, and tested an electric current tomograph suitable for applying the adaptive current algorithm described by D. Isaacson et al. (1988). Usable images can be obtained by a relatively primitive reconstruction algorithm. Demonstrable improvement in these images is obtained when optimal current patterns are used.<>
{"title":"Images from an adaptive current tomograph","authors":"J. Newell, D. Isaacson, D. Gisser, K. Cheng, J. Goble","doi":"10.1109/IEMBS.1988.94514","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.94514","url":null,"abstract":"The authors have designed, built, and tested an electric current tomograph suitable for applying the adaptive current algorithm described by D. Isaacson et al. (1988). Usable images can be obtained by a relatively primitive reconstruction algorithm. Demonstrable improvement in these images is obtained when optimal current patterns are used.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116164580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.94905
V. Goel, Yusung Kim, T. Lim, J. Weinstein
The finite-element technique is used to analyze the response of an intact ligamentous motion segment in axial compression mode. The three-dimensional nonlinear intact model is modified to simulate spinal stabilization using the Steffee screw-plate system. The results of the two models are compared to study the mechanics of load transfer across the Steffee system. The clinical implications of the results are described.<>
{"title":"Effects of spinal fixation devices on the motion segment mechanics","authors":"V. Goel, Yusung Kim, T. Lim, J. Weinstein","doi":"10.1109/IEMBS.1988.94905","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.94905","url":null,"abstract":"The finite-element technique is used to analyze the response of an intact ligamentous motion segment in axial compression mode. The three-dimensional nonlinear intact model is modified to simulate spinal stabilization using the Steffee screw-plate system. The results of the two models are compared to study the mechanics of load transfer across the Steffee system. The clinical implications of the results are described.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123906127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.94597
M.R. Islam, B. Towe
The problem of image reconstruction of multiple bioelectric dipolar current sources is considered. The authors report a novel image reconstruction method which is capable of finding not only the magnitude but also the orientation of dipoles for simple dipole combinations. The input simulated data is provided by a magnetoacoustic technique of noninvasive current measurement. The reconstruction method, called the vectorized iterative least-squares technique (V-ILST), is based on the classical ILST approach used in computerized tomography.<>
{"title":"Computer image reconstruction of bioelectric currents from magneto-acoustic measurements","authors":"M.R. Islam, B. Towe","doi":"10.1109/IEMBS.1988.94597","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.94597","url":null,"abstract":"The problem of image reconstruction of multiple bioelectric dipolar current sources is considered. The authors report a novel image reconstruction method which is capable of finding not only the magnitude but also the orientation of dipoles for simple dipole combinations. The input simulated data is provided by a magnetoacoustic technique of noninvasive current measurement. The reconstruction method, called the vectorized iterative least-squares technique (V-ILST), is based on the classical ILST approach used in computerized tomography.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122493028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.95269
D. Durand, H. Kayyali, E. Warman
Electrical fields applied to the cerebellum and the hippocampus have been shown to modulate the excitability of neurons provided that the electrical field is properly oriented with the dendritic structure. The effect of electrical fields has been tested on epileptiform electrical activity in order to determine the feasibility of blocking or reducing this type of abnormal neuronal firing. The experiments were done using the hippocampal slice in-vitro preparation, since it allows direct visual control of the position of the electrodes in order to align the electrical field with the dendrites. Epileptiform electrical activity was generated by adding 3500 units/ml of penicillin to the artificial cerebrospinal fluid solution. Low-intensity electrical fields were then applied with a monopolar or a tripolar electrode using constant current pulses. It is shown that it is possible to achieve a reduction in the amplitude of the electrical activity greater than 80%. Preliminary results have confirmed that neuronal firing is decreased by the applied fields.<>
{"title":"Control of abnormal electrical cavity with applied electrical fields","authors":"D. Durand, H. Kayyali, E. Warman","doi":"10.1109/IEMBS.1988.95269","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.95269","url":null,"abstract":"Electrical fields applied to the cerebellum and the hippocampus have been shown to modulate the excitability of neurons provided that the electrical field is properly oriented with the dendritic structure. The effect of electrical fields has been tested on epileptiform electrical activity in order to determine the feasibility of blocking or reducing this type of abnormal neuronal firing. The experiments were done using the hippocampal slice in-vitro preparation, since it allows direct visual control of the position of the electrodes in order to align the electrical field with the dendrites. Epileptiform electrical activity was generated by adding 3500 units/ml of penicillin to the artificial cerebrospinal fluid solution. Low-intensity electrical fields were then applied with a monopolar or a tripolar electrode using constant current pulses. It is shown that it is possible to achieve a reduction in the amplitude of the electrical activity greater than 80%. Preliminary results have confirmed that neuronal firing is decreased by the applied fields.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131398476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.95298
L. Narici, G. Romani, P. Rossini, I. Modena
Recent neuromagnetic studies indicate that suitable kinds of sensory stimulation can elicit enhanced responses correlated with underlying spontaneous activity, and that the study of these responses can shed light on the present preliminary results of a totally noninvasive neuromagnetic study on the spatial structure of these enhanced responses (in the somatosensory and visual modalities). Using the spatially discriminating capability of the neuromagnetic method, they provide evidence of the generation of these responses from the same sources responsible for the natural rhythms.<>
{"title":"Synchronized spontaneous brain activity: spatial and frequency content resolved via neuromagnetic measurements","authors":"L. Narici, G. Romani, P. Rossini, I. Modena","doi":"10.1109/IEMBS.1988.95298","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.95298","url":null,"abstract":"Recent neuromagnetic studies indicate that suitable kinds of sensory stimulation can elicit enhanced responses correlated with underlying spontaneous activity, and that the study of these responses can shed light on the present preliminary results of a totally noninvasive neuromagnetic study on the spatial structure of these enhanced responses (in the somatosensory and visual modalities). Using the spatially discriminating capability of the neuromagnetic method, they provide evidence of the generation of these responses from the same sources responsible for the natural rhythms.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114681263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.95028
G. T. Anderson, J. W. Valvano, R. R. Santos
Self-heated thermistor techniques to measure perfusion suffer from the lack of a widely accepted perfusion model. It has been previously proposed that perfusion be modeled as an effective thermal conductivity. It has also been proposed that effective and intrinsic tissue conductivities can be simultaneously measured using sinusoidal heating of thermistors embedded in tissue. A microcomputer-based instrument was built to measure effective and intrinsic thermal conductivity simultaneously. Measurements in alcohol-fixed canine kidneys supports both of the above hypotheses. It was determined that the optimal sinusoidal heating period to measure intrinsic conductivity in perfused tissue is 20 seconds.<>
{"title":"A self-heated thermistor technique to measure perfusion","authors":"G. T. Anderson, J. W. Valvano, R. R. Santos","doi":"10.1109/IEMBS.1988.95028","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.95028","url":null,"abstract":"Self-heated thermistor techniques to measure perfusion suffer from the lack of a widely accepted perfusion model. It has been previously proposed that perfusion be modeled as an effective thermal conductivity. It has also been proposed that effective and intrinsic tissue conductivities can be simultaneously measured using sinusoidal heating of thermistors embedded in tissue. A microcomputer-based instrument was built to measure effective and intrinsic thermal conductivity simultaneously. Measurements in alcohol-fixed canine kidneys supports both of the above hypotheses. It was determined that the optimal sinusoidal heating period to measure intrinsic conductivity in perfused tissue is 20 seconds.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132470895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.95324
R. Trenary
The reference neuron model of memory is predicted on a molecular mechanism which allows a pattern of neural activity to be controlled by a single (reference) neuron. This control is established through simultaneous activity of a reference neuron and neurons whose activity reflects environmental input. A computer simulation of a system navigating in an environment is used to explore the capabilities provided by memory processing based on the reference neuron. Simple manipulation of the memory structures demonstrates cognition corresponding to very-short-, short-, and long-term memory.<>
{"title":"Cognitive processes based on a molecular memory mechanism","authors":"R. Trenary","doi":"10.1109/IEMBS.1988.95324","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.95324","url":null,"abstract":"The reference neuron model of memory is predicted on a molecular mechanism which allows a pattern of neural activity to be controlled by a single (reference) neuron. This control is established through simultaneous activity of a reference neuron and neurons whose activity reflects environmental input. A computer simulation of a system navigating in an environment is used to explore the capabilities provided by memory processing based on the reference neuron. Simple manipulation of the memory structures demonstrates cognition corresponding to very-short-, short-, and long-term memory.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132130564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.94441
E.D. Morris, G. Saidel, G. Chisolm
Atherosclerosis is associated with an accumulation of low-density lipoprotein (LDL) in the arterial wall. To quantify transport processes involved in this phenomenon, tracer experiments are performed by exposing the arterial wall to labeled LDL. Distributed mathematical models are needed to describe the resulting LDL profiles in the tissue. Parameter values can be estimated by fitting model-generated profiles to experimental data. The authors believe that in vivo parameter estimates can be made more practical through the application of optimal experiment design analysis. Their analysis was based on an examination of the sensitivity coefficients and the Hessian matrix. Two experiment designs were considered. The findings indicate that it is possible to improve the precision of the estimates of in vivo transport parameters by designing experiments which use a labeled LDL tracer and a distinguishable, labeled LDL, chemically modified with tyramine-cellobiose.<>
{"title":"Optimal design of experiments for estimating arterial wall transport parameters","authors":"E.D. Morris, G. Saidel, G. Chisolm","doi":"10.1109/IEMBS.1988.94441","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.94441","url":null,"abstract":"Atherosclerosis is associated with an accumulation of low-density lipoprotein (LDL) in the arterial wall. To quantify transport processes involved in this phenomenon, tracer experiments are performed by exposing the arterial wall to labeled LDL. Distributed mathematical models are needed to describe the resulting LDL profiles in the tissue. Parameter values can be estimated by fitting model-generated profiles to experimental data. The authors believe that in vivo parameter estimates can be made more practical through the application of optimal experiment design analysis. Their analysis was based on an examination of the sensitivity coefficients and the Hessian matrix. Two experiment designs were considered. The findings indicate that it is possible to improve the precision of the estimates of in vivo transport parameters by designing experiments which use a labeled LDL tracer and a distinguishable, labeled LDL, chemically modified with tyramine-cellobiose.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121502830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.95050
P. Yager, J. Person, K. Seib
As a step in developing the potential of polymerizable lipids for stabilization of bilayers for biosensor applications, the authors have demonstrated that asymmetric bilayers consisting of one monolayer of polymerized diacetylenic lecithin and the other monolayer consisting of asolectin can support the function of alamethicin, although this function is somewhat modified. Single monolayers of 1, 2-bis- (10, 12-tricosadiynoyl)-sin-glycero- 3-phosphocholine (DC/sub 23/PC) were formed at the air-water interface and polymerized with a low-pressure mercury lamp. Other monolayers were formed from asolectin, and a patch electrode was passed through them to form an asymmetric bilayer. Membrane stabilization in the form of a substantial increase in the bilayer breakdown voltage was seen. When the ion-channel-forming peptide alamethicin was presented to the asolectin monolayer it formed channels through such bilayers, although the turn-on voltage for the channels was substantially higher and the conductivity lower than for symmetric asolectin bilayers.<>
{"title":"Development of ion-channel based biosensors using polymerizable lipids","authors":"P. Yager, J. Person, K. Seib","doi":"10.1109/IEMBS.1988.95050","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.95050","url":null,"abstract":"As a step in developing the potential of polymerizable lipids for stabilization of bilayers for biosensor applications, the authors have demonstrated that asymmetric bilayers consisting of one monolayer of polymerized diacetylenic lecithin and the other monolayer consisting of asolectin can support the function of alamethicin, although this function is somewhat modified. Single monolayers of 1, 2-bis- (10, 12-tricosadiynoyl)-sin-glycero- 3-phosphocholine (DC/sub 23/PC) were formed at the air-water interface and polymerized with a low-pressure mercury lamp. Other monolayers were formed from asolectin, and a patch electrode was passed through them to form an asymmetric bilayer. Membrane stabilization in the form of a substantial increase in the bilayer breakdown voltage was seen. When the ion-channel-forming peptide alamethicin was presented to the asolectin monolayer it formed channels through such bilayers, although the turn-on voltage for the channels was substantially higher and the conductivity lower than for symmetric asolectin bilayers.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133512910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-11-01DOI: 10.1109/IEMBS.1988.94400
A. Guerci, R. Beyar
To determine the anti-ischemic mechanism of intermittent occlusion of the coronary sinus (ICSO), the authors measured coronary arterial and sinus pressure and coronary arterial oxygen saturation before and after coronary artery litigation, with and without ICSO. In dogs, ICSO produced a systolic pressure gradient between the coronary artery and coronary sinus of -20+or-9 mm Hg (higher venous pressure, p<0.001) and a reduction in the oxygen of 20+or-13% (p<0.005). In parallel studied the authors constructed a mathematical model of known physiology to test the possibility of venoarterial flow. Predicted and experimental data were similar, indicating a reversal of flow at the microcirculatory level of ischemic regions during ISCO. These data indicate that alternating arteriovenous and venoarterial flow over the ischemic territory is the anti-ischemic mechanism of ICSO.<>
为了确定间歇性冠状窦闭塞(ICSO)的抗缺血机制，作者测量了冠状动脉阻塞前后、有ICSO和没有ICSO的冠状动脉动脉压和冠状动脉血氧饱和度。在犬中，ICSO使冠状动脉和冠状窦之间的收缩压梯度为-20+或9 mm Hg(静脉压升高，p>)
{"title":"Intermittent coronary sinus occlusion: hemodynamic and anti-ischemic effects","authors":"A. Guerci, R. Beyar","doi":"10.1109/IEMBS.1988.94400","DOIUrl":"https://doi.org/10.1109/IEMBS.1988.94400","url":null,"abstract":"To determine the anti-ischemic mechanism of intermittent occlusion of the coronary sinus (ICSO), the authors measured coronary arterial and sinus pressure and coronary arterial oxygen saturation before and after coronary artery litigation, with and without ICSO. In dogs, ICSO produced a systolic pressure gradient between the coronary artery and coronary sinus of -20+or-9 mm Hg (higher venous pressure, p<0.001) and a reduction in the oxygen of 20+or-13% (p<0.005). In parallel studied the authors constructed a mathematical model of known physiology to test the possibility of venoarterial flow. Predicted and experimental data were similar, indicating a reversal of flow at the microcirculatory level of ischemic regions during ISCO. These data indicate that alternating arteriovenous and venoarterial flow over the ischemic territory is the anti-ischemic mechanism of ICSO.<<ETX>>","PeriodicalId":227170,"journal":{"name":"Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132230963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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