Pub Date : 2002-12-01DOI: 10.1109/IEMBS.2002.1106483
B. Hoffmeister, B.S. Sheals, A. de Jongh, R. Malkin
Medical equipment can unintentionally allow the flow of power line current through the patient causing complete hemodynamic collapse without fibrillation. This study tests the hypothesis that static wall thickening accompanies AC induced collapse via an isovolumic state. In 3 dogs, we delivered AC current stimulation ranging from 10-160 Hz and 10-1000 /spl mu/A to the right ventricle. A steerable, quadripolar catheter was placed in the apex of the left ventricle and deflected towards the basal region to measure left ventricular volume. Two dimensional, short-axis ultrasound images of the LV endocardial walls were recorded to measure wall thickness. Our results indicate that wall thickness during collapse is significantly greater than during systole (/spl Delta/ thickness =11.7/spl plusmn/12 mm, p<0.001) and diastole (/spl Delta/ thickness=23.6/spl plusmn/13 mm, p<0.001). In addition, the volume of the left ventricle is significantly smaller during collapse than the average volume during normal sinus rhythm (/spl Delta/ impedance=0.152/spl plusmn/0.006 no units, p<0.001).
{"title":"Ventricular wall thickness and volume during hemodynamic collapse produced by AC leakage current","authors":"B. Hoffmeister, B.S. Sheals, A. de Jongh, R. Malkin","doi":"10.1109/IEMBS.2002.1106483","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1106483","url":null,"abstract":"Medical equipment can unintentionally allow the flow of power line current through the patient causing complete hemodynamic collapse without fibrillation. This study tests the hypothesis that static wall thickening accompanies AC induced collapse via an isovolumic state. In 3 dogs, we delivered AC current stimulation ranging from 10-160 Hz and 10-1000 /spl mu/A to the right ventricle. A steerable, quadripolar catheter was placed in the apex of the left ventricle and deflected towards the basal region to measure left ventricular volume. Two dimensional, short-axis ultrasound images of the LV endocardial walls were recorded to measure wall thickness. Our results indicate that wall thickness during collapse is significantly greater than during systole (/spl Delta/ thickness =11.7/spl plusmn/12 mm, p<0.001) and diastole (/spl Delta/ thickness=23.6/spl plusmn/13 mm, p<0.001). In addition, the volume of the left ventricle is significantly smaller during collapse than the average volume during normal sinus rhythm (/spl Delta/ impedance=0.152/spl plusmn/0.006 no units, p<0.001).","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"53 1","pages":"1461 vol.2-"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73785381","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1053285
Y. Petrov, D. Prough, D. Hilbert, D. Deyo, M. Motamedi, R. Esenaliev
Noninvasive monitoring of blood oxygenation (oxyhemoglobin saturation) offers great promise in the management of life-threatening illnesses including traumatic brain injury. We proposed and built a two-wavelength optoacoustic system to accurately and noninvasively monitor blood oxygenation in veins. The system includes nanosecond Nd:YAG and Alexandrite lasers and a specially designed optoacoustic probe. We tested the system in vitro in sheep blood with experimentally varied oxygenation and total hemoglobin concentration. Our results demonstrated that the system is capable of blood oxygenation measurements with high accuracy despite variation of total hemoglobin concentration. These results suggest that the two-wavelength optoacoustic technique can be used for patients with different or changing hemoglobin concentrations as may happen during infusion of blood-free fluids or as a consequence of hemorrhage.
{"title":"Two-wavelength optoacoustic technique for accurate, noninvasive, and continuous measurement of blood oxygenation","authors":"Y. Petrov, D. Prough, D. Hilbert, D. Deyo, M. Motamedi, R. Esenaliev","doi":"10.1109/IEMBS.2002.1053285","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1053285","url":null,"abstract":"Noninvasive monitoring of blood oxygenation (oxyhemoglobin saturation) offers great promise in the management of life-threatening illnesses including traumatic brain injury. We proposed and built a two-wavelength optoacoustic system to accurately and noninvasively monitor blood oxygenation in veins. The system includes nanosecond Nd:YAG and Alexandrite lasers and a specially designed optoacoustic probe. We tested the system in vitro in sheep blood with experimentally varied oxygenation and total hemoglobin concentration. Our results demonstrated that the system is capable of blood oxygenation measurements with high accuracy despite variation of total hemoglobin concentration. These results suggest that the two-wavelength optoacoustic technique can be used for patients with different or changing hemoglobin concentrations as may happen during infusion of blood-free fluids or as a consequence of hemorrhage.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"71 1","pages":"2287-2288 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85427693","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1106235
T. Collier, A. Lacy, A. Malpica, M. Follen, R. Richards-Kortum
Invasive carcinoma of the uterine cervix is preceded by a number of morphological intraepithelial changes. Real-time confocal microscopy has been demonstrated to be successful in imaging subcellular detail in-vivo. The purpose of this pilot study is to image ex-vivo tissue using a near real time confocal microscope and determine whether the images can be used to distinguish between normal and dysplastic tissue. Biopsies from 19 patients were imaged at various depths with our confocal microscope. Nuclear morphologic features were extracted from the confocal images. The morphologic feature measurements compare well with the pathologic examination. Discriminating the images for the presence of dysplasia using morphologic feature detection resulted in a sensitivity and specificity of 100% and 91%, respectively.
{"title":"Near real time confocal microscopy of amelanotic tissue: detection of dysplasia in ex-vivo cervical tissue","authors":"T. Collier, A. Lacy, A. Malpica, M. Follen, R. Richards-Kortum","doi":"10.1109/IEMBS.2002.1106235","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1106235","url":null,"abstract":"Invasive carcinoma of the uterine cervix is preceded by a number of morphological intraepithelial changes. Real-time confocal microscopy has been demonstrated to be successful in imaging subcellular detail in-vivo. The purpose of this pilot study is to image ex-vivo tissue using a near real time confocal microscope and determine whether the images can be used to distinguish between normal and dysplastic tissue. Biopsies from 19 patients were imaged at various depths with our confocal microscope. Nuclear morphologic features were extracted from the confocal images. The morphologic feature measurements compare well with the pathologic examination. Discriminating the images for the presence of dysplasia using morphologic feature detection resulted in a sensitivity and specificity of 100% and 91%, respectively.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"22 1","pages":"979-981 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81649412","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1137109
G. C. Engelmayr, Daniel K. Hildebrand, Fraser W. H. Sutherland, J. Mayer, M. Sacks
A novel bioreactor was developed for the purpose of studying the effect of dynamic flexural stimulation on the properties of tissue engineered heart valve (TEHV) scaffolds and constructs. While pulse duplicator and flow loop bioreactors have shown promise in the development of functional tissue engineered cardiovascular constructs, these devices present several drawbacks when applied to the study of fundamental biomechanical phenomena, including: small sample capacity, anatomical sample geometry, and coupled mechanical stimuli. In contrast, our bioreactor was designed to provide a simple, user-controllable mode of mechanical stimulation; cyclic three-point bending; offer a sufficient sample capacity for statistically significant comparisons at multiple time points, and accommodate a simple sample geometry amenable to mechanical testing. The bioreactor has the capacity to dynamically flex twelve rectangular samples (2.5 /spl times/ 0.75 /spl times/ 0.2 cm) under sterile conditions in a humidified cell culture incubator operating at 37/spl deg/C and 5 % CO/sub 2/.
{"title":"A novel bioreactor for the dynamic flexural stimulation of tissue engineered heart valve biomaterials","authors":"G. C. Engelmayr, Daniel K. Hildebrand, Fraser W. H. Sutherland, J. Mayer, M. Sacks","doi":"10.1109/IEMBS.2002.1137109","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1137109","url":null,"abstract":"A novel bioreactor was developed for the purpose of studying the effect of dynamic flexural stimulation on the properties of tissue engineered heart valve (TEHV) scaffolds and constructs. While pulse duplicator and flow loop bioreactors have shown promise in the development of functional tissue engineered cardiovascular constructs, these devices present several drawbacks when applied to the study of fundamental biomechanical phenomena, including: small sample capacity, anatomical sample geometry, and coupled mechanical stimuli. In contrast, our bioreactor was designed to provide a simple, user-controllable mode of mechanical stimulation; cyclic three-point bending; offer a sufficient sample capacity for statistically significant comparisons at multiple time points, and accommodate a simple sample geometry amenable to mechanical testing. The bioreactor has the capacity to dynamically flex twelve rectangular samples (2.5 /spl times/ 0.75 /spl times/ 0.2 cm) under sterile conditions in a humidified cell culture incubator operating at 37/spl deg/C and 5 % CO/sub 2/.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"16 1","pages":"853 vol.1-"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82207743","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1136994
D. Tschumperlin, J. Drazen
The epithelial lining of the asthmatic airway is exposed to compressive stress as a consequence of smooth muscle constriction. We have shown previously that in vitro compression of bronchial epithelial cells stimulates extracellular signal-regulated kinase (ERK) phosphorylation and downstream gene expression. Here we show that inhibition of signaling through the epidermal growth factor receptor (EGFR) with a tyrosine kinase inhibitor (AG1478) or a neutralizing antibody to the ligand-binding domain of the EGFR blocks compression-induced ERK phosphorylation. A metalloprotease inhibitor (Galardin) and a neutralizing antibody to heparin binding epidermal growth factor (HB-EGF), but not EGF, also attenuates the compression-induced ERK activation. Our results demonstrate that compressive activation of the ERK signaling pathway requires signaling through the EGFR, and involves metalloprotease-dependent shedding of HB-EGF.
{"title":"Transduction of compressive stress by bronchial epithelium","authors":"D. Tschumperlin, J. Drazen","doi":"10.1109/IEMBS.2002.1136994","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1136994","url":null,"abstract":"The epithelial lining of the asthmatic airway is exposed to compressive stress as a consequence of smooth muscle constriction. We have shown previously that in vitro compression of bronchial epithelial cells stimulates extracellular signal-regulated kinase (ERK) phosphorylation and downstream gene expression. Here we show that inhibition of signaling through the epidermal growth factor receptor (EGFR) with a tyrosine kinase inhibitor (AG1478) or a neutralizing antibody to the ligand-binding domain of the EGFR blocks compression-induced ERK phosphorylation. A metalloprotease inhibitor (Galardin) and a neutralizing antibody to heparin binding epidermal growth factor (HB-EGF), but not EGF, also attenuates the compression-induced ERK activation. Our results demonstrate that compressive activation of the ERK signaling pathway requires signaling through the EGFR, and involves metalloprotease-dependent shedding of HB-EGF.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"135 2 1","pages":"641-642 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79625708","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1136886
M. A. Sweigart, C. Zhu, C. M. Agrawal, T.C. Clanton, K. Athanasiou
The material properties of the baboon, bovine, canine, human, lapine, and porcine medial meniscus were determined in six locations: the anterior, central, and posterior portions of the femoral and tibial sides of the tissue. In situ creep and recovery indentation experiments were performed using a creep indentation apparatus. The entire creep curve was fitted with a finite element optimization method to determine the material properties. Results show significant variations in the aggregate modulus, Poisson's ratio, permeability, and shear modulus between the six testing locations both intraspecies and interspecies. In general, the canine model exhibits the highest aggregate and shear moduli, whereas the lapine model has the highest permeability and Poisson's ratio. The aggregate modulus and shear modulus in the human is the most similar to bovine. The human permeability values are the closest to the canine and baboon model. Overall, this study shows that caution must be exercised when comparing the menisci between different animal models.
{"title":"Biomechanical properties of the medial meniscus in experimental animal models","authors":"M. A. Sweigart, C. Zhu, C. M. Agrawal, T.C. Clanton, K. Athanasiou","doi":"10.1109/IEMBS.2002.1136886","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1136886","url":null,"abstract":"The material properties of the baboon, bovine, canine, human, lapine, and porcine medial meniscus were determined in six locations: the anterior, central, and posterior portions of the femoral and tibial sides of the tissue. In situ creep and recovery indentation experiments were performed using a creep indentation apparatus. The entire creep curve was fitted with a finite element optimization method to determine the material properties. Results show significant variations in the aggregate modulus, Poisson's ratio, permeability, and shear modulus between the six testing locations both intraspecies and interspecies. In general, the canine model exhibits the highest aggregate and shear moduli, whereas the lapine model has the highest permeability and Poisson's ratio. The aggregate modulus and shear modulus in the human is the most similar to bovine. The human permeability values are the closest to the canine and baboon model. Overall, this study shows that caution must be exercised when comparing the menisci between different animal models.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"16 1","pages":"442-443 vol.1"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80893882","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1053471
D. Silverthorn
Physiology is recognized as a core topic for biomedical engineering but the physiology courses taught to bioengineering students vary widely in scope and depth from institution to institution. As part of the NSF-sponsored VaNTH Engineering Research Center in Bioengineering Educational Technologies curriculum project, a group of bioengineering, physiology, and learning science faculty have been developing a physiology taxonomy that could guide curriculum development. The initial efforts focused on a systems-based taxonomy but we have now changed to a concepts-based taxonomy that will be cross-referenced with topics taught in system physiology courses. The final product will include resources for developing a learner-centered bioengineering physiology curriculum.
{"title":"Developing a concepts-based physiology curriculum for bioengineering: a VaNTH project","authors":"D. Silverthorn","doi":"10.1109/IEMBS.2002.1053471","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1053471","url":null,"abstract":"Physiology is recognized as a core topic for biomedical engineering but the physiology courses taught to bioengineering students vary widely in scope and depth from institution to institution. As part of the NSF-sponsored VaNTH Engineering Research Center in Bioengineering Educational Technologies curriculum project, a group of bioengineering, physiology, and learning science faculty have been developing a physiology taxonomy that could guide curriculum development. The initial efforts focused on a systems-based taxonomy but we have now changed to a concepts-based taxonomy that will be cross-referenced with topics taught in system physiology courses. The final product will include resources for developing a learner-centered bioengineering physiology curriculum.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"17 1","pages":"2646-2647 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89623543","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1053210
K. Momose, M. Saito
In order to develop a practical and rapid method to measure the chromatic contrast sensitivity function (CCSF), the sweet parameter technique (Norcia and Tyler, 1985) with an iso-luminant chromatic grating was investigated to determine whether this method can be applied to both normal subjects and subjects with defective color vision. Vertical sinusoidal isoluminant chromatic gratings presented on a color monitor were used as stimuli. The two colors for the gratings were selected from the colors on the dichromatic iso-chromatic lines. Steady-state VFPs were recorded during a continuous decrease of chromatic contrast at 10%/s. The amplitudes of the VEP component at twice of the temporal frequency of the stimulus were evaluated. VEPs elicited by 6, 8, and 10 Hz temporal frequencies, and 0.5, 1, and 2 c/deg spatial frequencies were recorded. For all stimulus conditions, the VEP amplitudes reproducibly decreased with a decrease of chromatic contrast. The modified sweep parameter technique resulted in large amplitudes and reproducible CCSF curves which should be effective for measuring defective color vision.
为了开发一种实用、快速的测量彩色对比灵敏度函数(CCSF)的方法，研究了采用等亮度彩色光栅的甜参数技术(Norcia and Tyler, 1985)，以确定该方法是否可以同时适用于正常受试者和色视觉缺陷受试者。用彩色显示器上呈现的垂直正弦等光彩色光栅作为刺激。光栅的两种颜色是从二色同色线上的颜色中选择的。在色对比度以10%/s的速度连续下降时记录稳态VFPs。在刺激时间频率的两倍处，评估了VEP分量的振幅。记录6、8、10 Hz时间频率和0.5、1、2 c/℃空间频率诱发的vep。在所有刺激条件下，VEP振幅均可再现性地随着色差的降低而降低。改进的扫描参数技术获得了幅值大、可重现的CCSF曲线，可以有效地测量色觉缺陷。
{"title":"Determination of the chromatic contrast sensitivity using sweep VEP technique","authors":"K. Momose, M. Saito","doi":"10.1109/IEMBS.2002.1053210","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1053210","url":null,"abstract":"In order to develop a practical and rapid method to measure the chromatic contrast sensitivity function (CCSF), the sweet parameter technique (Norcia and Tyler, 1985) with an iso-luminant chromatic grating was investigated to determine whether this method can be applied to both normal subjects and subjects with defective color vision. Vertical sinusoidal isoluminant chromatic gratings presented on a color monitor were used as stimuli. The two colors for the gratings were selected from the colors on the dichromatic iso-chromatic lines. Steady-state VFPs were recorded during a continuous decrease of chromatic contrast at 10%/s. The amplitudes of the VEP component at twice of the temporal frequency of the stimulus were evaluated. VEPs elicited by 6, 8, and 10 Hz temporal frequencies, and 0.5, 1, and 2 c/deg spatial frequencies were recorded. For all stimulus conditions, the VEP amplitudes reproducibly decreased with a decrease of chromatic contrast. The modified sweep parameter technique resulted in large amplitudes and reproducible CCSF curves which should be effective for measuring defective color vision.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"1 1","pages":"2145-2146 vol.3"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88620112","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1106370
D. D. Soerensen, T.B.N. Christensen, Z. He, S. He, A. Yoganathan
Three mitral valves (MV) with annulus, leaflets, chordae tendineae (CT) and papillary muscles (PM) were extracted intact from fresh porcine hearts. The valves were inserted in an in vitro left heart simulator that provided physiological flow and transmitral pressures. Four C-shaped chordal force transducers were attached to four chordae tendineae; anterior strut, basal posterior, marginal posterior stem and a commissure. All four chordae originated from the posteromedial papillary muscle. The force transducers measured the force exerted on the four individual chordae during cardiac cycles, under different conditions: two peak transmitral pressures (120 mmHg and 150 mmHg) and three papillary muscle positions (normal, taut and slack). Taut was 5 mm from normal position, and slack 3 mm from normal position. The chordal force distribution changed with papillary muscle displacement. The anterior strut and the basal posterior chordae bore the biggest tension in normal and taut position, whereas the posterior marginal stem bore most of the tension in the slack papillary muscle position. Increasing transmitral pressure increased the magnitude of the chordal forces, but not the force distribution between the chordae.
{"title":"Configuration of the mitral valves subvalvular complex and its effect on the chordal force distribution","authors":"D. D. Soerensen, T.B.N. Christensen, Z. He, S. He, A. Yoganathan","doi":"10.1109/IEMBS.2002.1106370","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1106370","url":null,"abstract":"Three mitral valves (MV) with annulus, leaflets, chordae tendineae (CT) and papillary muscles (PM) were extracted intact from fresh porcine hearts. The valves were inserted in an in vitro left heart simulator that provided physiological flow and transmitral pressures. Four C-shaped chordal force transducers were attached to four chordae tendineae; anterior strut, basal posterior, marginal posterior stem and a commissure. All four chordae originated from the posteromedial papillary muscle. The force transducers measured the force exerted on the four individual chordae during cardiac cycles, under different conditions: two peak transmitral pressures (120 mmHg and 150 mmHg) and three papillary muscle positions (normal, taut and slack). Taut was 5 mm from normal position, and slack 3 mm from normal position. The chordal force distribution changed with papillary muscle displacement. The anterior strut and the basal posterior chordae bore the biggest tension in normal and taut position, whereas the posterior marginal stem bore most of the tension in the slack papillary muscle position. Increasing transmitral pressure increased the magnitude of the chordal forces, but not the force distribution between the chordae.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"7 1","pages":"1246-1247 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86984913","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 : 2002-12-01DOI: 10.1109/IEMBS.2002.1106611
J. Winter, C. E. Flynn, T.S. Liu, A. Belcher, B. Korgel, C. Schmidt
Continued advances in the design of prosthetic devices will demand increasingly smaller and more precise connections. We are developing a single cell device capable of specific molecular interactions using semiconductor quantum dots (qdots). The qdots are placed in direct proximity to individual cellular receptors using biorecognition molecules. These molecules may be incorporated into the passivation layer of the quantum dot or may be presented as an external molecule. In this manner, we have successfully created qdot-nerve cell interfaces utilizing both peptides and antibodies. Ultimately, the qdots will be excited optically, eliciting a change in the nerve cell membrane potential. The change in nerve cell membrane potential will be measured using a microelectrode array currently under development. These devices will allow researchers to determine the effect of electrical excitation on individual nerve-cell receptors and enhance development of molecular neuroprosthetics.
{"title":"Semiconductor-neural interfaces","authors":"J. Winter, C. E. Flynn, T.S. Liu, A. Belcher, B. Korgel, C. Schmidt","doi":"10.1109/IEMBS.2002.1106611","DOIUrl":"https://doi.org/10.1109/IEMBS.2002.1106611","url":null,"abstract":"Continued advances in the design of prosthetic devices will demand increasingly smaller and more precise connections. We are developing a single cell device capable of specific molecular interactions using semiconductor quantum dots (qdots). The qdots are placed in direct proximity to individual cellular receptors using biorecognition molecules. These molecules may be incorporated into the passivation layer of the quantum dot or may be presented as an external molecule. In this manner, we have successfully created qdot-nerve cell interfaces utilizing both peptides and antibodies. Ultimately, the qdots will be excited optically, eliciting a change in the nerve cell membrane potential. The change in nerve cell membrane potential will be measured using a microelectrode array currently under development. These devices will allow researchers to determine the effect of electrical excitation on individual nerve-cell receptors and enhance development of molecular neuroprosthetics.","PeriodicalId":60385,"journal":{"name":"中国地球物理学会年刊","volume":"26 1","pages":"1704-1705 vol.2"},"PeriodicalIF":0.0,"publicationDate":"2002-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87060062","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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