检索结果-内蒙古大学图书馆

Contributors to the Lab on a Chip cell and tissue engineering in microsystems special issue

Lab on a Chip 2007年第6期7卷 667-671页

作者： Bhatia, sangeeta N. Chen, Christoper Bashir, Rashid Beebe, David J. Desai, Tejal Gottwald, Eric Khademhosseini, Ali Langer, Robert S. Piel, Matthieu Takayama, Shuichi Thorsen, Todd Tien, Joe Voldman, Joel Vunjak-Novakovic, Gordana Wu, Mingming Yu, Hanry Massachusetts Institute of Technology Harvard-MIT Division of Health Sciences and Technology Department of Electrical Engineering and Computer Science United States Laboratory for Multiscale Regenerative Technologies United States Department of Innovation University of Pennsylvania Department of Bioengineering United States Cell Biology and Physiology Program Cell Growth and Cancer Program Tissue Microfabrication Laboratory Department of Electrical and Computer Engineering and Biomedical Engineering Purdue University United States Department of Electronics University of Glasgow United Kingdom Department of Physiology and Bioengineering University of California San Francisco CA United States California Institute for Quantitative Biomedical Research UCSF/UC Berkeley Graduate Group in Bioengineering United States Laboratory of Therapeutic Micro and Nanotechnology Institute for Biological Interfaces Germany 3D-Cell Culture Techniques Group Institute for Biological Interfaces Germany Department of Medicine and Health Sciences and Technology Massachusetts Institute of Technology (MIT) United States Institut Curie UMR 144 IC/CNRS France Biomedical Engineering Department University of Michigan United States Department of Biomedical Engineering Macromolecular Science and Engineering Program United States Sibley School of Mechanical and Aerospace Engineering School of Chemical and Molecular Engineering Cornell University United States National University of Singapore Singapore Institute of Bioengineering and Nanotechnology A STAR Singapore

A graphical abstract is available for this content

关键词：

来源：评论

学校读者我要写书评

暂无评论

Regulation of vascular smooth muscle cells and mesenchymal stem cells by mechanical strain

引用

MCB Molecular and Cellular Biomechanics 2006年第1期3卷 21-34页

作者： Kurpinski, Kyle Park, Jennifer Thakar, Rahul G. Li, Song Department of Bioengineering University of California at Berkeley Berkeley CA United States Joint Graduate Program in Bioengineering UC Berkeley Berkeley CA United States Joint Graduate Program in Bioengineering UC San Francisco San Francisco CA United States

Vascular smooth muscle cells (SMCs) populate in the media of the blood vessel, and play an important role in the control of vasoactivity and the remodeling of the vessel wall. Blood vessels are constantly subjected to hemodynamic stresses, and the pulsatile nature of the blood flow results in a cyclic mechanical strain in the vessel walls. Accumulating evidence in the past two decades indicates that mechanical strain regulates vascular SMC phenotype, function and matrix remodeling. Bone marrow mesenchymal stem cell (MSC) is a potential cell source for vascular regeneration therapy, and may be used to generate SMCs to construct tissue-engineered vascular grafts for blood vessel replacements. In this review, we will focus on the effects of mechanical strain on SMCs and MSCs, e.g., cell phenotype, cell morphology, cytoskeleton organization, gene expression, signal transduction and receptor activation. We will compare the responses of SMCs and MSCs to equiaxial strain, uniaxial strain and mechanical strain in three-dimensional culture. Understanding the hemodynamic regulation of SMC and MSC functions will provide a basis for the development of new vascular therapies and for the construction of tissue-engineered vascular, grafts. Copyright © 2006 Tech Science Press.

关键词： Muscle

来源：评论

学校读者我要写书评

暂无评论

Biomimetic in silico devices

Biomimetic in silico devices

引用

International Conference on Computational Methods in Systems Biology, CMSB 2004

作者： Hunt, C. Anthony Ropella, Glen E. P. Roberts, Michael S. Yan, Li Dept. of Biopharmaceutical Sciences Biosystems Group University of California San Francisco CA 94143-0446 United States Department of Medicine University of Queensland Princess Alexandra Hospital Woolloongabba Q 4102 Australia Joint UCSF UC Berkeley Bioengineering Graduate Program

ISBN: (纸本)3540253750

We introduce biomimetic in silico devices, and means for validation along with methods for testing and refining them. The devices are constructed from adaptable software components designed to map logically to biological components at multiple levels of resolution. In this report we focus on the liver;the goal is to validate components that mimic features of the lobule (the hepatic primary functional unit) and dynamic aspects of liver behavior, structure, and function. An assembly of lobule-mimetic devices represents an in silico liver. We validate against outflow profiles for sucrose administered as a bolus to isolated, perfused rat livers. Acceptable in silico profiles are experimentally indistinguishable from those of the in situ referent. This new technology is intended to provide powerful new tools for challenging our understanding of how biological functional units function in vivo. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Biomimetic materials

来源：评论

学校读者我要写书评

暂无评论

Simulation of depth of interaction effects for pinhole SPECT

Simulation of depth of interaction effects for pinhole SPECT

引用

IEEE Symposium on Nuclear Science (NSS/MIC)

作者： A.B. Hwang K. Iwata B.H. Hasegawa Bioengineering Graduate Program University of California Berkeley and San Francisco USA Department of Radiology University of California San Francisco San Francisco CA USA Department of Nuclear Engineering University of California Berkeley Berkeley CA USA

Pinhole imaging is receiving attention as a method to enable SPECT of small animals. However, gamma rays passing through the pinhole aperture and entering the detector at an oblique angle can cause parallax errors due to the depth of interaction (DOI) of the incident gamma ray in the absorber layer of the detector. This can cause a displacement and blurring of the position coordinates recorded by the detector, resulting in an error known as the "DOI effect". The DOI effect for projection data can be analytically calculated, but the error due to the DOI effect in reconstructed SPECT images is difficult to predict analytically due to the complexity of reconstruction algorithms. Therefore, we used an analytic model of the DOI effect in the projection data to numerically simulate the acquisition of point sources to determine the point spread function at different points in the object. The resulting projection data were reconstructed using a Feldkamp algorithm, from which point spread functions were extracted to quantify loss in spatial resolution due to the DOI effect. The simulations were performed for 140-keV gamma rays and a 6 mm thick CsI scintillator with a reconstruction volume of (40 mm)/sup 3/. The simulation was repeated with a 10 mm thick high purity germanium (HPGe) detector. These detectors and parameters are representative of a system that can be used for small animal imaging. From these calculations, we estimate tomographic reconstruction contributes a resolution loss of 0.32-0.63 mm FWHM in plane and 0.21-0.42 mm FWHM out of plane of the detector. For the CsI scintillator, the DOI effect contributes a maximum resolution loss of 0.5 mm FWHM in plane and 0.3 mm FWHM out of plane. With the HPGe detector, the DOI effect contributes a spatial resolution loss of 0.6 mm FWHM in plane and 0.5 mm out of plane.

关键词： Image reconstruction Spatial resolution Animals Gamma rays Gamma ray detection Gamma ray detectors Image analysis Algorithm design and analysis Optical imaging Apertures

来源：评论

学校读者我要写书评

暂无评论

Design and utility of a small animal CT/SPECT system

Design and utility of a small animal CT/SPECT system

引用

IEEE Symposium on Nuclear Science (NSS/MIC)

作者： K. Iwata A.B. Hwang M.C. Wu H.R. Tang A.J. Da Silva K.H. Wong M.W. Dae B.H. Hasegawa Department of Radiology University of California San Francisco San Francisco CA USA Bioengineering Graduate Program University of California Berkeley and San Francisco USA Department of Radiology University of California San Francisco San Francisco USA Department of Nuclear Engineering University of California Berkeley Berkeley CA USA

Recent developments in the genetic engineering of small animals have motivated us to design an in vivo dual-modality CT/SPECT system that can be used to localize and quantify uptake of single-photon radiotracers in mice. The CT system includes a 75-W x-ray tube and a CCD camera, while the radionuclide imager incorporates a CsI(TI) scintillator coupled to a Si photodiode array with interchangeable pinhole collimators. These devices are mounted on a slip-ring gantry to image a 40-mm diameter cylindrical volume, where both modalities share a common field of view without moving the table on which the animal lies horizontally. The calculated modulation transfer function of the radionuclide system exceeds 10% at 1.01p/mm. The spatial resolution of the CT system is 0.1 mm with at scan time of 15 min and a contrast resolution of 1% for soft tissue. The high-resolution CT image can be used to provide a priori information to correct both the visual quality and the quantitative accuracy of the SPECT image. This imaging system and technique is designed for in vivo functional assessments of cancer and cardiovascular disease in small animals.

关键词： Animals Computed tomography In vivo Spatial resolution Genetic engineering Mice X-ray imaging Charge coupled devices Charge-coupled image sensors Photodiodes

来源：评论

学校读者我要写书评

暂无评论

Movement dysfunction following repetitive hand opening and closing: Anatomical analysis in owl monkeys

引用

Movement Disorders 2001年第2期14卷

作者： Kimberly S. Topp PhD, PT Nancy N. Byl PhD, PT University of California San Francisco-SFSU Graduate Program in Physical Therapy UCSF Department of Anatomy UCSF-UCB Program in Bioengineering UCSF Department of Family Practice and Community Medicine San Francisco California U.S.A.

Repetitive strain injuries are thought to result from biomechanical stress and tissue microtrauma. The purpose of this study was to investigate the presence of local inflammation, scarring or anatomical variations of the flexor tendons and the median and ulnar nerves in four Owl monkeys behaviorally trained at a repetitive motor or sensory task. Three monkeys were trained to repetitively open and close a handpiece. The two monkeys that used rapid, stereotypical hand squeezing developed a task-specific movement dysfunction (one in 5 weeks and one in 24 weeks). The third monkey used a variable shoulder-pulling strategy and did not develop movement problems. The fourth monkey served as a control subject for the repetitive motor movements, trained on a repetitive sensory task, and did not develop a task-specific movement dysfunction. On dissection and histologic staining, there were no signs of active inflammation in the median nerve, the ulnar nerve, or the flexor tendons in any of the monkeys. However, the monkey that developed movement problems after 5 weeks of repetitive hand squeezing had an anatomical restriction of the flexor profundus tendon on the fourth digit of the trained side and the third digit of the untrained side. Reorganization of the representation of the hand on the contralateral somatosensory cortex (area 3b) was noted in the two monkeys that developed motor control problems and in the monkey performing the repetitive sensory task. These findings suggest that repetitive, stereotypical motor behaviors can lead to motor control problems without local signs of tendon or nerve inflammation. Preexisting anatomical restrictions may modify the time course for the development of movement dysfunction under conditions of stressful repetition. This animal model may simulate clinical focal hand dystonia (or occupational hand cramps) which can develop in human subjects who perform prolonged, repetitive, stereotypical movements.

关键词： Median nerve Ulnar nerve Tendinitis Flexor profundus Somatosensory cortex Repetitive strain injury Dystonia Occupational cramp Writer's cramp

来源：评论

学校读者我要写书评

暂无评论

Characterization of the mechanical and ultrastructural properties of heat-treated cortical bone for use as a bone substitute

引用

Journal of Biomedical Materials Research Part B: Applied Biomaterials 1999年第4期45卷

作者： Joseph Catanese III J. D. B. Featherstone Tony M. Keaveny Orthopaedic Biomechanics Laboratory Department of Mechanical Engineering 6175 Etcheverry Hall University of California Berkeley California 94720-1740 Joint Graduate Program in Bioengineering University of California Berkeley and San Francisco San Francisco California 94143 Department of Restorative Dentistry University of California San Francisco California 94143 Department of Orthopaedic Surgery University of California San Francisco California 94143

Heat-treated bovine cortical bone has been proposed as an alternative to bone grafts and synthetic bone substitutes because it may combine the advantages of allografts (high stiffness and strength) and synthetic materials (abundant supply, reduced risk of rejection and disease transfer). Its mechanical properties and ultrastructure, however, are not well characterized. To address this, we compared the compressive ( n = 20, bovine bone) and tensile ( n = 26, bovine bone) mechanical properties and the ultrastructure ( n = 12, human bone) of intact versus 350°C heat-treated cortical bone. The 350°C heat-treated bone had a mean ± SD elastic modulus similar to the intact bone for both compression (16.3 ± 2.2 GPa, pooled; p = 0.68) and tension (16.3 ± 3.7 GPa, pooled; p = 0.95). It also maintained 63% of the intact strength in compression but only 9% in tension ( p < 0.001). Infrared scans and X-ray diffraction patterns showed no differences between the 350°C heat-treated and intact bone but large differences between ashed (700°C) and intact bone. Similarly, heat-treated bone previously has been shown to be biocompatible and osteoconductive. We conclude, therefore, that 350°C heat-treated cortical bone may be an excellent load-bearing bone substitute provided that it is loaded in compression only in vivo and is shown by future work to have acceptable fatigue properties.© 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 45, 327–336, 1999.

关键词： bone substitute artificial bone mechanical properties ultrastructure heated bone

来源：评论

学校读者我要写书评

暂无评论

Temporal image database design for outcome analysis of lung nodule

引用

COMPUTERIZED MEDICAL IMAGING AND GRAPHICS 1996年第4期20卷 347-356页

作者： Zhu, XM Lee, KN Levin, DL Wong, STC Huang, HK Hoo, KS Gamsu, G Webb, WR Department of Radiology University of California at San Francisco San Francisco CA 94143 USA Department of Diagnostic Radiology Dong-A University Pusan 602-103 Korea Bioengineering Graduate Program UCSF/UC Berkeley San Francisco CA 94143 USA Department of Radiology Cornell University Medical College New York NY 10021 USA

This paper presents the design of a temporal image database system and its application in thoracic imaging. The design of this information system is based on the client/server architecture. The system consists of a chest imaging database server, a library of image processing modules, a link to the picture archiving and communication system (PACS) archive, and a low end client workstation with motif-based graphic user interface (GUI). The database system can be used to aid the radiologists in quantitating solitary or multiple lung nodules and in assessing effectiveness of therapeutic procedures for these lung cancers. The GUI allows a user to retrieve any patient study from PACS. After a nodule is visually identified, it will be segmented automatically to obtain relevant features, such as the center of mass, volume, and surface area. Such 3D nodule information, together with the patient textual information, is subsequently organized in the chest imaging database to facilitate outcome analysis. Copyright (C) 1996 Elsevier Science Ltd.

关键词： temporal image database image processing image segmentation image display outcome analysis PACS spiral CT lung nodule

来源：评论

学校读者我要写书评

暂无评论

Postfailure compressive behavior of tibial trabecular bone in three anatomic directions

引用

Journal of Biomedical Materials Research Part B: Applied Biomaterials 1996年第3期31卷

作者： J. H. Keyak I. Y. Lee D. S. Nath H. B. Skinner Rehabilitation Research and Development Service Department of Veterans Affairs Medical Center San Francisco California Bioengineering Graduate Group University of California San Francisco/Berkeley Department of Orthopaedic Surgery University of California San Francisco California Bioengineering Undergraduate Program University of California Berkeley Department of Mechanical Engineering University of California Berkeley California Department of Orthopaedic Surgery University of California Irvine California

To obtain information describing the postfailure behavior of human proximal tibial trabecular bone, cube specimens of bone were mechanically tested in compression beyond the point of failure. Tests were performed in the three anatomic directions, plots of stress versus strain were obtained, and measures to describe the stress-strain relations before, during, and after failure were defined. These measures included elastic modulus, strength, postfailure slope, strain during maximum stress, and first postfailure minimum stress. For each anatomic direction, analyses were performed to correlate these parameters with ash density. Each of these measures was significantly correlated with ash density at the p < 0.05 level for all test directions, except for postfailure slope, which was correlated in the mediolateral and superior-inferior directions, and strain during maximum stress, which was correlated only in the superior-inferior direction. The data from this study enable trilinear stress-strain relations to be estimated for proximal tibial trabecular bone of various densities, and can serve as a first step toward modeling the behavior of trabecular bone before, during, and after failure. © 1996 John Wiley & Sons, Inc.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Energy dependent systematic errors in dual-energy X-ray CT

Energy dependent systematic errors in dual-energy X-ray CT

引用

IEEE Symposium on Nuclear Science (NSS/MIC)

作者： K.L. Goh S.C. Liew B.H. Hasegawa Department of Physics National University of Singapore Singapore Program in Computational Science National University of Singapore Singapore Department of Radiology and Bioengineering Graduate Group University of California San Francisco USA

Dual-energy X-ray Computed Tomography (DECT) is a technique which is designed to allow the determination of energy-independent material properties. In this study, results of computer simulation show that energy-dependent systematic errors exist in the values of attenuation coefficient synthesized using the basis material decomposition technique with acrylic and aluminum as the basis materials, especially when iodine (e.g., from radiographic contrast media) is present in the body. The errors are reduced when acrylic and an iodine-water mixture are used as the basis materials. The authors propose a simple model for the calculation of energy-dependent systematic errors using effective energies at the lower and higher energy windows of the X-ray spectrum used in the DECT system. The calculated errors agree well with the errors observed in the simulation. These results suggest that the observed systematic errors are predominantly due to the energy dependence of the basis material coefficients.

关键词： Attenuation Aluminum Computed tomography Computational modeling X-ray imaging Material properties Radiography Computer errors Physics computing Radiology

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：