Pub Date : 1992-10-01DOI: 10.1109/IEMBS.1992.5761123
S. Demir, John W. Clark, W. Giles
We have developed a mathematical model for a rabbit crista terminalis cell which is based on experimental results from whole-cell voltage clamp recordings as well as action potential data from enzymatically isolated single pacemaker cells. It consists of two parts, a Hodgkin-Huxley (HH) model of sarcolemma, and a fluid compartment model of the intra- and extracellular media. The HH model includes equations for the known ionic currents (INa, ICa, L, ICa, T, IK, Ito, If, IK1, ICl) in mammalian cardiac pacemaker cells, as well as the Na+ /K+ and Ca2+ pumps and the Na+ /Ca2+ exchanger. The fluid compartment model is based on a material balance for the ion concentrations in the intracellular medium (Na+, K+ and Ca2+); the concentrations are assumed to be constant in the extracellular medium. Provision is made for Ca2+ buffering in the intracellular medium, as well as the uptake and release of Ca2+ by the sarcoplasmic reticulum (SR). We simulate the functional role of each channel by discussing and comparing the model-generated results with the data. Our model is able to provide good fits to experimental data from several published sources, and therefore can be used to provide insights into the biophysical interactions of the ionic currents that generate the pacemaker potential and action potential in a rabbit crista terminalis cell.
{"title":"The crist a terminalis cell in the rabbit heart: A model","authors":"S. Demir, John W. Clark, W. Giles","doi":"10.1109/IEMBS.1992.5761123","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5761123","url":null,"abstract":"We have developed a mathematical model for a rabbit crista terminalis cell which is based on experimental results from whole-cell voltage clamp recordings as well as action potential data from enzymatically isolated single pacemaker cells. It consists of two parts, a Hodgkin-Huxley (HH) model of sarcolemma, and a fluid compartment model of the intra- and extracellular media. The HH model includes equations for the known ionic currents (I<inf>Na</inf>, I<inf>Ca, L</inf>, I<inf>Ca, T</inf>, I<inf>K</inf>, I<inf>to</inf>, I<inf>f</inf>, I<inf>K1</inf>, I<inf>Cl</inf>) in mammalian cardiac pacemaker cells, as well as the Na<sup>+</sup> /K<sup>+</sup> and Ca<sup>2+</sup> pumps and the Na<sup>+</sup> /Ca<sup>2+</sup> exchanger. The fluid compartment model is based on a material balance for the ion concentrations in the intracellular medium (Na<sup>+</sup>, K<sup>+</sup> and Ca<sup>2+</sup>); the concentrations are assumed to be constant in the extracellular medium. Provision is made for Ca<sup>2+</sup> buffering in the intracellular medium, as well as the uptake and release of Ca<sup>2+</sup> by the sarcoplasmic reticulum (SR). We simulate the functional role of each channel by discussing and comparing the model-generated results with the data. Our model is able to provide good fits to experimental data from several published sources, and therefore can be used to provide insights into the biophysical interactions of the ionic currents that generate the pacemaker potential and action potential in a rabbit crista terminalis cell.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"36 1","pages":"587-588"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73422446","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5762036
F. Zhao, D. Jiang
Usually, using high and low energy x-ray images we can decompose into soft tissue image and bone image. That is based on that different materials have different attenuation coefficient ratios of high energy x-ray to low energy x-ray. We apply this principle to different materials in soft tissues with different average atomic number, it can further separate image of different tissues such as lung tissue and connective tissue like bronchus. This method has been proved by experiment and it has potential use for identifying the composition of soft tissues.
{"title":"Multiple decomposition technique for dual energy x-ray image","authors":"F. Zhao, D. Jiang","doi":"10.1109/IEMBS.1992.5762036","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5762036","url":null,"abstract":"Usually, using high and low energy x-ray images we can decompose into soft tissue image and bone image. That is based on that different materials have different attenuation coefficient ratios of high energy x-ray to low energy x-ray. We apply this principle to different materials in soft tissues with different average atomic number, it can further separate image of different tissues such as lung tissue and connective tissue like bronchus. This method has been proved by experiment and it has potential use for identifying the composition of soft tissues.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"1 1","pages":"1778-1779"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79899579","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5760860
J. Berry, A. Rachev, James E. Moore, J. Meister
Arterial wall stresses may play a role in the formation and progression of cardiovascular diseases. The residual stresses present in the unloaded state of arteries have been shown to affect the distribution of stresses in a homogeneous model of the artery wall. It is possible that differences between the mechanical behavior and residual stress states in the media and adventitia further affect the stress distribution. Predictions of the effects of different strain energy density functions and zero stress states in these two layers were made, based on the results of previosly published studies. It was predicted that the circumferential stress at the inner wall was within 2% of the value at the outer wall in the loaded state. These results illustrate the importance of taking into account the mechanical properties and non-circular stress free states in the media and adventitia when analyzing arterial wall stresses.
{"title":"Analysis of the effects of a non-circular two layer stress-free state on arterial wall stresses","authors":"J. Berry, A. Rachev, James E. Moore, J. Meister","doi":"10.1109/IEMBS.1992.5760860","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5760860","url":null,"abstract":"Arterial wall stresses may play a role in the formation and progression of cardiovascular diseases. The residual stresses present in the unloaded state of arteries have been shown to affect the distribution of stresses in a homogeneous model of the artery wall. It is possible that differences between the mechanical behavior and residual stress states in the media and adventitia further affect the stress distribution. Predictions of the effects of different strain energy density functions and zero stress states in these two layers were made, based on the results of previosly published studies. It was predicted that the circumferential stress at the inner wall was within 2% of the value at the outer wall in the loaded state. These results illustrate the importance of taking into account the mechanical properties and non-circular stress free states in the media and adventitia when analyzing arterial wall stresses.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"53 1","pages":"65-66"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82167278","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5761102
Weiqun Yang, L. Horan, N. Flowers
A method for beat-by-beat recording of late potentials using adaptive filters is presented. An orthogonal lead set viewed as individual XYZ leads is employed for better detection of late potentials. The use of bidirectional and finite impulse response filters prevent filter ringing at the terminal QRS. Beat-by-beat late potentials detected from patients with ventricular tachycardia indicate the potential of this method, yet optimal filter parameters and quantitative criteria for detecting late potential are to be further investigated.
{"title":"Adaptive enhancement of ventricular late potentials using orthogonal beat-by-beat recordings","authors":"Weiqun Yang, L. Horan, N. Flowers","doi":"10.1109/IEMBS.1992.5761102","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5761102","url":null,"abstract":"A method for beat-by-beat recording of late potentials using adaptive filters is presented. An orthogonal lead set viewed as individual XYZ leads is employed for better detection of late potentials. The use of bidirectional and finite impulse response filters prevent filter ringing at the terminal QRS. Beat-by-beat late potentials detected from patients with ventricular tachycardia indicate the potential of this method, yet optimal filter parameters and quantitative criteria for detecting late potential are to be further investigated.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"7 1","pages":"547-548"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82559129","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5761950
O. Hiwaki, S. Ueno
This study focuses on the properties of nerve excitation elicited by time-varying magnetic fields. We analyzed the effects of trapezoidal magnetic fields on the nerve transmembrane potential. Nerve excitation processes were simulated, changing the rise-time, the duration of plateau and fall-time of the trapezoid. The results show that exciting point and threshold for nerve excitation change with the time course of the magnetic fields, even if stimulating intensity is at same level.
{"title":"Nerve excitation processes stimulated by trapezoidal magnetic fields","authors":"O. Hiwaki, S. Ueno","doi":"10.1109/IEMBS.1992.5761950","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5761950","url":null,"abstract":"This study focuses on the properties of nerve excitation elicited by time-varying magnetic fields. We analyzed the effects of trapezoidal magnetic fields on the nerve transmembrane potential. Nerve excitation processes were simulated, changing the rise-time, the duration of plateau and fall-time of the trapezoid. The results show that exciting point and threshold for nerve excitation change with the time course of the magnetic fields, even if stimulating intensity is at same level.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"25 1","pages":"1614-1615"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82593468","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5761280
Bernhard Hirsch, G. Thallinger, H. Maresch
In the course of the project Neurosurgical Expert System for the Support of Decisins in Dignosis and Therpy research work has also been done to facilitate an efcient integration of the expert system within the environment of a clinical information retrieval system. The achieved improvement of the interface concern the way of Inserting new patient data in the information system, the portability of the sofware in relation to the underlying database management system and performance increasing measures with regard to extracting information out of the datbase as the input facts of the expert system.
{"title":"Expert system for a neurosurgical clinic — Standardization and optimization of the interface between clinical information retrieval system and expert system","authors":"Bernhard Hirsch, G. Thallinger, H. Maresch","doi":"10.1109/IEMBS.1992.5761280","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5761280","url":null,"abstract":"In the course of the project Neurosurgical Expert System for the Support of Decisins in Dignosis and Therpy research work has also been done to facilitate an efcient integration of the expert system within the environment of a clinical information retrieval system. The achieved improvement of the interface concern the way of Inserting new patient data in the information system, the portability of the sofware in relation to the underlying database management system and performance increasing measures with regard to extracting information out of the datbase as the input facts of the expert system.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"3 1","pages":"860-861"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81457707","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5761349
B. Davies, R. Hibberd, W. Ng, A. Timoney, J. Wickham
This paper describes the work on a prototype robotic system for removal of prostate tissue. The Robotic system has been specifically designed for the purpose and has been tried clinically. This represents a world first in the removal of quantities of tissue from human patients using a robotic system. The background to the design of the system hardware and software is discussed, together with the system constraints which have led to the series of clinical experiments.
{"title":"A robotics assistant for prostate surgery","authors":"B. Davies, R. Hibberd, W. Ng, A. Timoney, J. Wickham","doi":"10.1109/IEMBS.1992.5761349","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5761349","url":null,"abstract":"This paper describes the work on a prototype robotic system for removal of prostate tissue. The Robotic system has been specifically designed for the purpose and has been tried clinically. This represents a world first in the removal of quantities of tissue from human patients using a robotic system. The background to the design of the system hardware and software is discussed, together with the system constraints which have led to the series of clinical experiments.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"24 1","pages":"1052-1053"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81769136","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5762057
P. Charbonnier, M. Barlaud, L. Blanc-Féraud
A new iterative method using regularization and designed to preserve sharp edges is compared to classical reconstruction techniques in SPECT.
与传统的SPECT图像重建方法相比，提出了一种新的正则化迭代方法。
{"title":"Iterative SPECT reconstruction using a regularization which preserves sharp edges: Comparison to classical methods","authors":"P. Charbonnier, M. Barlaud, L. Blanc-Féraud","doi":"10.1109/IEMBS.1992.5762057","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5762057","url":null,"abstract":"A new iterative method using regularization and designed to preserve sharp edges is compared to classical reconstruction techniques in SPECT.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"25 1","pages":"1823-1824"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81891986","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5760963
J. Ryaby, R. Fitzsimmons, F. P. Magee, A. Weinstein, D. Baylink
Cells and tissues respond to a large variety of extracellular signals, including electromagnetic fields (EMF). Recent studies have demonstrated that combined AC and DC magnetic fields may couple specifically to ion dependent cellular processes. This coupling suggests an extraordinary potential for use of these combined magnetic fields for tissue healing applications in clinical situations. To this end, we have perfomed studies on in vitro osteoblast and in vivo rat osteoporosis model systems. Since osteoporosis is a result of impaired bone formation/bone resoprtion, we proposed to test whether direct osteoblast activation via calcium-dependent pathways would prevent bone loss in a model of hormonally induced osteoporosis. The cellular studies addressed the question of whether combined magnetic fields could induce cell proliferation, and whether this effect was based on autocrine growth factor (insulin-like growth factor; IGF-II) stimulation by osteoblasts.
{"title":"Biophysical stimulation of tissue healing mediated by IGF-II","authors":"J. Ryaby, R. Fitzsimmons, F. P. Magee, A. Weinstein, D. Baylink","doi":"10.1109/IEMBS.1992.5760963","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5760963","url":null,"abstract":"Cells and tissues respond to a large variety of extracellular signals, including electromagnetic fields (EMF). Recent studies have demonstrated that combined AC and DC magnetic fields may couple specifically to ion dependent cellular processes. This coupling suggests an extraordinary potential for use of these combined magnetic fields for tissue healing applications in clinical situations. To this end, we have perfomed studies on in vitro osteoblast and in vivo rat osteoporosis model systems. Since osteoporosis is a result of impaired bone formation/bone resoprtion, we proposed to test whether direct osteoblast activation via calcium-dependent pathways would prevent bone loss in a model of hormonally induced osteoporosis. The cellular studies addressed the question of whether combined magnetic fields could induce cell proliferation, and whether this effect was based on autocrine growth factor (insulin-like growth factor; IGF-II) stimulation by osteoblasts.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"6 1","pages":"278-278"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82121192","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 : 1992-10-01DOI: 10.1109/IEMBS.1992.5761897
J. Walter, J. Wheeler, C. Morgan, P. Zaszczurynski, M. Plishka
Urodynamic evaluation of stress incontinence has failed to result in consistent diagnostic parameters. Using retrospective female bladder pressure and urine flow data, we evaluated two parameters based on a conductance formula. This formula was derived from fitting a classical fluid dynamic equation to published data of voiding cystourethography. The Area Equivalent Factor-female at maximal flow represents maximal urethral opening and this value further divided by the pressure is the urethral compliance. A stress incontinent group had a strong trend toward greater maximal urethral opening and urethral compliance than a continent group. These parameters may, therefore, have potential in the evaluation and understanding of stress urinary incontinence.
{"title":"Measurement of urethral compliance in females with stress incontinence","authors":"J. Walter, J. Wheeler, C. Morgan, P. Zaszczurynski, M. Plishka","doi":"10.1109/IEMBS.1992.5761897","DOIUrl":"https://doi.org/10.1109/IEMBS.1992.5761897","url":null,"abstract":"Urodynamic evaluation of stress incontinence has failed to result in consistent diagnostic parameters. Using retrospective female bladder pressure and urine flow data, we evaluated two parameters based on a conductance formula. This formula was derived from fitting a classical fluid dynamic equation to published data of voiding cystourethography. The Area Equivalent Factor-female at maximal flow represents maximal urethral opening and this value further divided by the pressure is the urethral compliance. A stress incontinent group had a strong trend toward greater maximal urethral opening and urethral compliance than a continent group. These parameters may, therefore, have potential in the evaluation and understanding of stress urinary incontinence.","PeriodicalId":6457,"journal":{"name":"1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society","volume":"16 1","pages":"1502-1503"},"PeriodicalIF":0.0,"publicationDate":"1992-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82471718","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：