bluuebunny/crossref_metadata_2025 huggingface dataset:
Allogeneic Cells and Tissues
Authors: Knight Richard , Ingham Eileen
Published: April 2006

The advent of regenerative medicine and tissue engineering has led to a new generation of biomedical engineers engaged in research in this exciting arena. The biomedical engineer is faced with many new concepts, many of which entail a detailed understanding of complex biological systems. The aims of this chapter are to convey essential information regarding the nature and uses of allogeneic cells and tissues in regenerative medicine. A brief introduction to cells and tissues and their development is followed by a description of histocompatibility genes and proteins. The basics of how the immune system functions, with particular emphasis on transplantation immunology and the mechanisms of rejection of allogeneic cells and tissues are then explained. Current techniques used for tissue typing and immunosuppression are covered as well as their implications. The chapter then focuses on the potential use of allogeneic cells and tissues in regenerative medicine and tissue engineering applications. Current technologies that make use of allogeneic tissues are then discussed, followed by future developments that aim to overcome rejection of allogeneic cells.
American College of Clinical Engineering
Authors: Gieras Izabella A.
Published: April 2006

The American College of Clinical Engineering (ACCE) was established with a special focus on promoting the profession of clinical engineering in the United States and in the international arena. With members across the globe, the ACCE is the only professional society for clinical engineers with international recognition. Clinical engineers are health‐care professionals who work in hospitals, medical device industry, research and development, academic institutions, consulting, regulatory agencies, and other medical technology‐based institutions. Their main focus is to apply engineering and management background to enhance patient care. With this focus in mind, clinical engineers work very closely with biomedical engineering technologists, physicians, clinicians, information technologists, risk managers, system engineers, construction engineers, procurement, and other health‐care professionals. The ACCE's multidisciplinary activities engage ACCE members in national and international conferences, educational workshops, teleconferences, professional partnerships, and medical device industry initiatives, thus further fostering the profession of clinical engineering.
American Institute for Medical and Biological Engineering
Authors: Lee Jen-Shih
Published: April 2006

The American Institute for Medical and Biological Engineering (AIMBE) was established in 1991 to unify the medical and biological engineering community to address public policy issues important to the people and the nation. AIMBE has four constituents: College of Fellows, Council of Societies, Academic Council, and Industry Council. The 19 member societies of the Council of Societies represent some 50,000 engineers, scientists, and scholars. A total of 85 academic departments or education programs are members of the Academic Council. AIMBE organizes an Annual Meeting in Washington, D.C. in the springtime to showcase the scientific and technological progresses in medical and biological engineering and to provide a forum for the deliberation of public policy and its implementation strategies. The advocacy role of AIMBE has contributed to the successful passage of the Biomaterials Availability Act in 1998 and the timely establishment of the National Institute for Biomedical Imaging and Bioengineering as the 19th Institute of the National Institutes of Health to support the development and to accelerate the application of biomedical technologies to improve human health. AIMBE is an organization of volunteers. A capital campaign was kicked off in 2003 for expanding the operation and support of AIMBE. With this new resource, AIMBE is to embark onto its ongoing challenge to activate and energize the unused potential of the membership of its constituents to achieve AIMBE's missions of benefiting our society and nation by influencing public policy in medical and biological engineering.
Analog to Digital Conversion
Authors: Paarmann Larry D.
Published: April 2006

The process of converting an analog, or continuous time, signal into a digital signal is known as analog‐to‐digital conversion (ADC). Many signals are inherently analog. Examples of analog signals obtained from a transducer abound. Other analog signals are inherently electrical, such as those obtained from biomedical electromyography or electroencephalography electrodes. In many cases, it is deemed desirable to process a signal by a microprocessor or computer to extract information, or to store the signal in some digital storage medium such as a hard drive, a floppy disk, or a CD ROM. If the original signal is in analog format, in such cases, it is necessary to convert the analog signal into an equivalent digital signal.

This article describes the process of ADC. It introduces the topic and describes the operation of two of the most common methods of accomplishing ADC: the successive approximation ADC and the flash ADC. The sampling theorem is stated and proved, aliasing is described, and quantization noise is discussed. Oversampling is described, and the resultant improvements in ADC performance are documented.

Then delta‐sigma ADCs are introduced and described. Conventional first‐order and second‐order delta‐sigma ADCs are described and evaluated. Performance comparisons among simple oversampling, first‐order delta‐sigma, and second‐order delta‐sigma ADCs are documented. The article concludes with an example of a higher order delta‐sigma ADC performance evaluation.
Anesthesia Machines
Authors: Roca-Dorda Joaquin , Álvarez-Gômez José , Roca-González Joaquín , Jiménez-Martínez Jacinto , Gil-Sánchez Francisco J.
Published: April 2006

Since the introduction of general anesthesia in 1846, surgical procedures may be carried out while the patient remains insensitive to pain and other external stimuli. As with many other manufactured products, the machines used for anesthesia have changed as technology developed within the industrial and military fields. In this sense, it is easy to understand that modern anesthesia machines include accurate electronic sensors, complex embedded computers, and high‐precision mechanic elements in order to ease the operative procedures to the anesthesiologists and, at the same time, grant the security of the patient. Although anesthesia has been generally described as the part of the medical profession that ensures that the patient remains insensitive to pain and other stimuli during surgical operations, the currently accepted role for the anesthesiologist includes all of the procedures that have to be performed to offer a completely balanced anesthesia. For this purpose, the anesthetic equipment used in many operating rooms includes the machines required for the delivery of vaporized and intravenous agents in order to allow the proper sedation method for each patient and surgical procedure. This chapter will try to provide an operationally centered review of the different elements such as the gas supply system, the gas mixing subsystem, the vaporizer for inhaled agents, the mechanical ventilator, the breathing circuit of the patient, the absorber of CO
2
removal, the infusion pumps required for intravenous anesthesia, and the monitoring subsystem for patient and equipment supervision.
Atomic Force Microscopy
Authors: Myhra Sverre
Published: April 2006

Atomic force microscopy, AFM, has emerged as the most widely used member of a group of related techniques known as scanning probe microscopy, SPM. The physical principle of the technique consists of a surface being probed by a sharp tip, in a manner where the strength of interaction between surface and tip is sensed by a lever transducer. In the context of biomedical engineering AFM has the particular merit of being able to image and manipulate bio‐systems with molecular spatial resolution and at strengths of interactions down to the low‐pN range. The versatility and richness of AFM analysis arise from the range of operational modes. Those include contact, lateral force and intermitting contact imaging modes, where the contrast arises, respectively, from topography, lateral chemical differentiation, and mapping of variations in mechanical stiffness. In the force‐sensing/imposing modes the probe‐to‐surface interaction is monitored as a function of distance and can provide insight into molecular binding and recognition, bio‐molecular folding, intra‐cellular structure and dynamics. The AFM system also constitutes a platform for exploration of novel bio‐sensor concepts.
Biochemical Pathways Research
Authors: Sherley James L.
Published: April 2006

All life on the planet is based on a set of basic biochemical reactions that provide energy transformation, biosynthesis, metabolism, and catabolism in cells. A unique feature of biochemistry is that chemical reactions are catalyzed by enzymes, which are chemistry‐specific in their action. Conceptually, enzymes and the biomolecules on which they act are arranged in pathways of sequential biochemical reactions. Biochemical pathway research has been a major force in the development of the principles of biomedicine and has greatly impacted medical knowledge and practice. In recent years, engineering disciplines like biomedical engineering have set their sights on elucidation and manipulation of cells as a strategy to making advances in biomedical research and medicine. However, in large part, these early efforts have been divorced of longstanding knowledge and scientific principles that are the fruits of biochemical pathway research. Improved progress in cell and tissue engineering in the future will require recognition that the failure to incorporate biochemical pathway concepts and knowledge in biomedical engineering pursuits is a severely limiting oversight. Such a paradigmatic shift in intellectual framework and approach will not be without significant challenges, but the certain gains in biological knowledge and effective medical applications more than outweigh such reservations.
Biocompatibility of Engineering Materials
Authors: Baier Robert
Published: April 2006

After 30 years of human implantation of various commodity materials, backed up byin vitroand animal studies along the way, a secure knowledge base now exists regarding the critical bioadhesive phenomena encountered by biomedical devices that must resist or develop secure biological attachments. Well‐healed “osseointegrated” implants in human jaws signaled the significant—and, in many ways, surprising—advances that attention to surface properties and, especially, to surface cleanliness and surface energy of biomedical materials could foster for related systems.

Two of the many active, successful areas of current patient benefits from biocompatible engineering materials are dental restoratives and prosthetic implants. Others include the continuing development of surgical adhesives, extracorporeal circuits, cardiovascular devices, fixed‐film processors, bioreactors, and even improved coatings for the prevention of marine fouling on commercial ships. A short review of the fundamental issues in some of these areas follows to illustrate the branches of medicine that are being addressed and how the technology of biocompatibility control assists in each of them.

It is emphasized that principles of adhesion science and technology, respected at the earliest stages of these efforts, were and remain the key principles allowing safe and effective interfacing of engineering materials with biological systems.

One major difficulty that had to be overcome in many early studies of biomedical implants for any use, be it in the dental, orthopedic, or cardiovascular environment, had been the tendency of the investigators to focus mainly on either the mid‐term (hours to days) and the longer term behavior of the materials—from weeks to months to years post‐implantation. There are numerous active research programs to provide proper characterization and detailed knowledge of the original surface states of these implants at their time of placement and of the early bioadhesive sequela (over minutes, hours, and days) converting the initial surface properties to others that promote or inhibit adhesion of formed biological elements (such as tissue cells or bacteria).
Resorbable Materials in Orthopedic Surgery
Authors: Borden Mark
Published: April 2006

Current techniques in orthopedic surgery use of a variety of implants that are specifically designed to aid in the healing of bones, ligaments, and tendons throughout the skeleton. These implants are commonly used to provide temporary mechanical support and stabilization to the site of the injury while the tissue heals. However, once their function is complete, the implants remain and can be a source of long‐term complications. Resorbable implants, on the other hand, are a unique class of devices that have the ability to breakdown into harmless byproducts that are absorbed by the body. Composed of polymers, ceramics, or composites, these versatile materials have different mechanisms of resorption, degradation profiles, and mechanical properties. As a result, they have been used in a variety of clinical applications including fracture repair, sports medicine, and bone grafting. This chapter discusses the requirements and function of resorbable orthopedic devices and reviews the properties and healing behavior of common resorbable materials.
Bioimpedance
Authors: Grimnes Sverre , Martinsen Ørjan G.
Published: April 2006

Bioimpedance describes the passive electrical properties of biological materials and serves as an indirect transducing mechanism for physiological events, often in cases where no specific transducer for that event exists.

The studied biomaterial may be living tissue, dead tissue, or organic material. Tissue is composed of cells with poorly conducting, thin‐cell membranes; therefore, tissue has capacitive properties: the higher the frequency, the lower the impedance. Tissue is also anisotropic. Impedance spectroscopy, hence, gives important information about tissue and membrane structures, as well as intra‐ and extracellular liquid distributions.

The three most common electrode systems are described. Typical results obtained with three‐ and four‐electrode systems are shown, and dispersion is explained. The effect of electrode polarization is demonstrated.

The importance of system geometry, sensitivity, and reciprocity is explained. How bioimpedance can be used for volume measurements (plethysmography) is described. The sensitivity field of an electrode system is defined and explained and examples are provided.

Bioimpedance electrical models are based on tissue showing relaxation, but not resonance, phenomena. The choice between an impedance or admittance model is underlined. The Constant Phase Element (CPE) and the Cole models are critically described, and a new general model is introduced.

Some electrode design concepts are treated. Lock‐in amplifiers are the preferred instrumentation for bioimpedance measurements, together with advanced software for data analysis. The electrical safety aspects are treated.

Selected applications and future trends are described. Bibliography and sources for reference data are given.
Biomedical Transducers
Authors: Togawa Tatsuo
Published: April 2006

A transducer is a device that converts a measured object quantity into an electrical signal. Biomedical transducers are transducers with specific uses in biomedical applications, such as physiological measurement and patient monitoring, and in health care. The object quantities in biomedical measurements are physical and chemical quantities that reflect the physiological functions in a living body. Although some quantities, such as blood composition, can be determined from a sample extracted from the body, real‐time and continuous measurements can be achieved if a transducer is attached to the body, and use of a transducer attached to the body is essential when continuous monitoring of an object quantity is required.
Blood Flow Measurement
Authors: Masood Sharmeen , Yang Guang-Zhong
Published: April 2006

The measurement of blood flow is important to the understanding and management of cardiovascular disease. The development of new imaging methods has allowed detailed quantification of
in vivo
blood flow that has traditionally been difficult. Both invasive and noninvasive methods have been used to measure blood flow, and this chapter outlines the main techniques of blood flow measurement for cardiovascular research and practical clinical applications. A brief history and the basic principles of each of the methods are presented along with their relative merits and potential pitfalls. Recent development of noninvasive imaging techniques has allowed detailed depiction and quantification of
in vivo
flow patterns, the main focus of this chapter is therefore directed towards Doppler ultrasound and cardiovascular magnetic resonance (CMR). The future trend of combining different imaging modalities for investigating the relationships between morphological structure and the hemodynamic properties of flow is also outlined.
Bulk Modulus
Authors: Aritan Serdar
Published: April 2006

Understanding and characterizing the mechanical response of soft biological tissues is a fundamental problem in biomechanics. Adequate models are needed to allow the study of both normal tissue function and the effects of disease and injury on these tissues.

The mechanical behavior of biological materials is determined by their structure. The factors which control mechanical response include the gross (bulk) and microscopic tissue morphology, the chemical composition of the tissue, fluid flow in the tissue, directionality of tissue fibre structures, and the interfaces between various structures.
Computer Aided Design
Authors: Knopf George K. , Johnson James A.
Published: April 2006

Computer‐aided design (CAD) plays a key role in a variety of medical applications including prosthesis design, surgical implant design, blood flow analysis, preoperative planning for surgical operations, and computer‐assisted surgery. CAD tools and technology developed for mechanical design have been successfully applied to geometric modeling, visualizing, animating, and analyzing the natural functional behavior of anatomical structures including human skeletal and vascular systems. These shape modeling and visualization tools provide a significant amount of design information concerning object shape, dimensional parameters, component materials, material flow, and interference checking. New developments in virtual reality (VR) and rapid prototyping (RP) technologies have also enabled biomedical engineers to create detailed three‐dimensional (3‐D) models of anatomical structures directly from the CAD database. The immersive VR environments provide designers, physicians, and surgeons with the ability to interactively manipulate the geometric CAD models with 3‐D displays and haptic devices. In contrast, the fabricated RP prototypes give surgeons a realistic hard copy of complex structures before a medical implant is inserted or a surgical procedure is performed. The shift from the purely graphical interpretation of complex geometric models displayed on a computer monitor to an interactive visual‐tactile representation of the anatomical structure has the ability to deliver a new level of spatial understanding to designers and medical personnel.
Cancer
Authors: Yang Jia-Lin , Yu Yan
Published: April 2006

Cancer is a group of lethal diseases caused by uncontrolled growth and spread of abnormal cells. The cause is often not clear, which makes early diagnosis and effective treatment very difficult. Advances in biomedical engineering have allowed for the development of novel diagnostic and therapeutic methods via different approaches ranging from engineered biomolecules to cells to tissues that have improved cancer research and treatment dramatically. This chapter introduces some applications of biomedical engineering in cancer diagnosis and treatment.
Cell Adhesion Molecules – Conversational Signalers
Authors: Douglas Mike R. , Buckley Christopher D.
Published: April 2006

Cellular actions and fates—gene expression, differentiation, proliferation, apoptosis, and migration—are modulated by a sequence of signals that include the multiple adhesive contacts found between cells and their extracellular environment. A family of cell surface proteins, termed cell adhesion molecules, are important in mediating interactions. These proteins are segregated into distinct families with a wide range of physical properties. Some members exhibit strong binding properties, important for the maintenance of tissue integrity, whereas other members form weaker, more dynamic binding interactions, which are important during cellular migration processes. Research has demonstrated that these proteins are extremely versatile biological players, not only providing a form of cellular glue but also providing a means for coordinating a wide range of intracellular signaling events (including receptor tyrosine kinases and phosphatases), which have important functional consequences for processes as diverse as gene expression, cellular differentiation, migration, proliferation, and apoptosis. This review will briefly highlight the physical and biochemical properties that categorize cell surface molecules as adhesion molecules and demonstrate how these proteins form important modulators of cellular conversation by acting as assembly points for cytosolic adaptor proteins. The examples in this review are restricted to the signaling events coordinated by the integrin, immunoglobulin superfamily (Ig) cell adhesion molecules, cadherin/catenin families, and the selectins. These families exhibit a broad spectrum of biophysical and biochemical characteristics and yet all clearly demonstrate common dynamic interactions, forming multiprotein complexes linked to intracellular proteins and resultant signaling events.
Chaos
Authors: Cohen Maurice E.
Published: April 2006

The theory of chaos was developed approximately 30 years ago and initially applied in meteorology. Chaotic systems are characterized by nonlinear representations whose long‐term behavior is sensitive to initial conditions. Although the results may appear random, the systems are in fact deterministic and repeatable if all conditions remain the same. Chaos theory has been applied to the analysis of biomedical time series, especially in electrocardiogram analysis for examination of cardiac disorders. Chaotic analysis is based on the use of one or more measures of chaos that include both graphical and numerical representations. Most chaotic models are discrete in nature.

Examination of continuous models shows that some chaotic behavior is from the discrete representation, and the methods derived from continuous modeling can be used in both chaotic and nonchaotic situations. Chaos, nonlinear dynamics, and complex systems have become linked and have expanded into new areas of application in biomedicine, including examination of interactions of multiple components from the cellular to the body system level.
Clinical Trials
Authors: Bartoo Grace T.
Published: April 2006

Human subject studies or clinical trials of a medical device are often required before a new device can be sold in the marketplace. The goal of a human subject study is to show safety and efficacy of a new device. However, the history of using human subjects in experiments has had a checkered past, resulting in a mass of governmental regulation aimed at ensuring reasonable subject safety while enforcing reliable scientific method. This article offers a brief overview of the structure, relevant regulations, and major steps that make up a clinical trial. It defines the roles of the various participants and emphasizes the responsibilities required of the sponsor and the clinical investigator. A brief overview of relevant regulations, standards, and guidance documents is given, with specific links to useful websites. In addition, the different regulatory requirements of significant versus nonsignificant risk devices are discussed. Finally, a synopsis of the preparation, execution, and analysis and reporting of clinical studies is given. Human clinical trials are complex, but when methodical efforts are made to follow and comply with regulatory and scientific requirements, reliable data can be generated while treating human subjects in an ethical and safety‐conscious manner.
Closed‐Loop System Identification
Authors: Baselli Giuseppe , Bolzern Paolo
Published: April 2006

System identification concerns modeling of system dynamics through the choice of suitable mathematical laws and the estimate of their parameters from experimental data. General issues of open‐loop identification and input/output prediction error methods are briefly recalled in order to introduce the problems of closed‐loop identification. The main approaches to closed‐loop identification of feedback control systems are mentioned: direct, indirect, and joint process. Hypotheses required for each approach are stressed and asymptotic results concerning estimate consistency, accuracy, and bias in the frequency domain are provided. Major classes of biomedical application problems are introduced: modeling of physiological control systems, artificial control of physiological variables, and human/machine interaction.
Cochlear Implants
Authors: McDermott Hugh J.
Published: April 2006

Cochlear implants (CIs) are electronic systems that provide a partial replacement of the sense of hearing to people who have hearing impairment that cannot be alleviated adequately by means of conventional acoustic aids. In most cases of hearing loss, conventional aids that function principally as sound amplifiers are satisfactory. However, if the loss of hearing sensitivity in both ears is severe or profound, particularly across a wide range of frequencies, then amplification with conventional hearing aids may be inadequate. CIs have been developed to bypass the dysfunctional parts of the auditory system. They create hearing sensations by delivering electric stimuli directly to the auditory nerve via one or more electrodes located inside the cochlea (or inner ear). Recipients of CIs wear a device similar in appearance to an acoustic hearing aid on the external ear. This device contains a microphone, a signal processor, and a battery. In most existing CI systems, the external device transmits digitally encoded signals to an implanted receiver‐stimulator via a pair of inductively coupled coils. The implanted device decodes these signals and generates precisely controlled pulses of current that are delivered to the electrodes to stimulate the auditory neurons. The patterns of current pulses are designed to represent selected components of the sound signal received by the microphone. Over the past 30 years, a considerable research effort has led to the development of various algorithms that convert sound signals into electric stimuli for CIs. The most successful of these schemes enable numerous CI users to understand speech and recognize many other types of sound by hearing alone, at least in favorable listening conditions. By the end of 2005, over 70,000 adults and children around the world were recipients of CI systems.
Coherence
Authors: Ropella Kristina M. , Imas Olga A.
Published: April 2006

Coherence is a frequency‐domain measure of the linear correlation between two time series that has been used extensively in biomedical signal processing applications. A number of numerical methods exist for estimating coherence from two or more time series, including time‐frequency implementations for nonstationary processes. Coherence may also be used for system identification. Examples of coherence spectra applied to the description of cardiac arrhythmias, and electrical and hemodynamic brain activity are emphasized in this article.
Blood Flow Simulation, Patient‐Specificin‐vivo
Authors: Merrifield Robert , Long Quan , Xu Yun , Yang Guang-Zhong
Published: April 2006

The blood flow patternsin vivoare complex. They vary considerably from subject to subject and even more so in patients with cardiovascular diseases. Despite the importance of studying such flow patterns, the field is relatively immature primarily because of previous limitations in the methodologies involved in acquiring and calculating expected flow details. Althoughin vivoimaging provides a valuable investigative tool, the range of hemodynamic properties that can be measured is limited. Computational fluid dynamics (CFD), on the other hand, offers a complementary approach that permits the simulation of blood flow within patient specific cardiovascular models. It allows the calculation of high‐resolution flow fields and hemodynamic indices that cannot be measured using imaging alone. The parallel advancement of magnetic resonance imaging and CFD has now come to a stage that their combined application will allow for a more accurate and detailed measurement of complex flow patterns. This article introduces the main processes involved in flow simulation including imaging, segmentation, meshing, and numerical simulation. For each of these issues, the current approach and remaining challenges are discussed.
Computer Aided Surgery
Authors: Cleary Kevin , Buersmeyer Todd , Wood Bradford J. , Glossop Neil
Published: April 2006

Computer‐aided surgery, in which computers are used to provide image guidance to physicians for invasive procedures, is still a relatively new field. Most developments have come over the last 10 years. Systems based on bony landmarks for applications such as the brain, spine, and ear, nose, and throat are now commercially available, and some institutions use them as the standard for care. However, systems for abdominal interventions and for other procedures with substantial organ motion and deformation have not yet been developed, and they constitute an area of current research.

A typical computer‐aided surgery system has three major components: a control computer, a localizer for tracking instruments, and software for image processing and display. The localizer can be optical or electromagnetic; however, most commercial systems use optical localizers. Electromagnetic localizers show promise for future applications, including tracking of internal organs, but recent technological advances have only now rendered them serious contenders for this purpose.

Computer‐aided surgery is an active area of research and emphasizes collaborations between biomedical engineers and clinical experts. Research areas include integration of real‐time modalities, such as ultrasound, to provide intraoperative updates; modeling of soft‐tissue deformation and respiratory motion; new registration and tracking techniques; multimodal image fusion; and improvement of visualization methods.
Electrical Impedance Technique for Cryosurgery Monitoring
Authors: Abboud Shimon , Radai Michal M. , Zlochiver Sharon
Published: April 2006

Monitoring the extent of the forming ice‐ball, used for destroying cancerous tissue, during cryosurgery procedures is of great importance, especially where the destruction of healthy tissue might cause irreversible functional damage (e.g., in brain cryosurgery). As a result of the extremely high electrical resistivity of a frozen tissue, impedance technique and electrical impedance tomography (EIT) have been suggested as global monitoring and imaging modalities, as a substitute to existing monitoring methods such as magnetic resonance imaging (MRI), computed tomography (CT), or ultrasound (US). In this review, the implications of using the suggested monitoring techniques are discussed, including advantages and limitations with respect to other imaging/monitoring modalities. A concise description of the physical model and mathematical formulation of the forward and inverse problems of EIT is depicted. The results obtained from several theoretical and experimental studies are presented, and the feasibility and prospective issues of impedance technique in cryosurgery is argued.
Data Mining
Authors: Kothari Ravi
Published: April 2006

Organized data banks and inexpensive computation prompt the use of data mining techniques for improving our understanding of biological organisms. This article provides a broad overview of data mining using three reference applications: mining of sequence data, mining of gene expression (micro‐array) data, and the mining of biomedical literature.
Biological Database Integration
Authors: Miled Zina Ben , Liu Yang , Li Nianhua , Bukhres Omran
Published: April 2006

Many biomedical databases have rapidly become a central part of knowledge discovery in numerous fields including genomics, proteomics, and drug design. These databases are distributed, heterogeneous, and autonomous. This article by presenting a brief overview of some widely used databases to motivate the need for the integration of the distributed biological databases. Supporting this integration faces numerous challenges including various levels of heterogeneity, limited accessibility and redundancy, or conflicts in the data. These challenges are discussed, and different approaches to addressing these issues are presented. The article also includes a comparison among some integration systems that have been proposed for biological databases.
Electrocardiogram (ECG): Automated Diagnosis
Authors: Fotiadis Dimitris , Likas Aristidis , Michalis Lampros , Papaloukas Costas
Published: April 2006

Electrocardiogram (ECG) is one of the most common signals used in medical practice because of its noninvasive nature and the information it contains. Its analysis can be used to assess the pathophysiological condition of the heart. Several systems for ECG recording and analysis have been developed for more than a century. Early ECG systems included recording and printing of the signal. Modern systems use computer technology to provide automated diagnosis. The latter is a significant research field and many methods and approaches have been proposed for the detection of ischemia, arrhythmia detection and classification, and diagnosis of chronic myocardial diseases. Those methods are based on the processing of the signal to remove noise and artifacts, extraction of certain features related to diseases, and analysis of the features to obtain the final decision. The analysis is usually based on signal processing, fuzzy logic, and artificial neural networks concepts, mixed with knowledge provided by medical experts. Today, those systems are evaluated using standard databases and must be introduced in clinical practice to be further validated.
Ectopic Activity
Authors: Saiz Javier , Monserrat Marta , Ferrero José María , Gomis-Tena Julio , Chorro Francisco J.
Published: April 2006

The term ectopic activity is used to indicate situations in which the electrical stimulus responsible for the contraction of the heart originates in a zone of the cardiac tissue (ectopic focus) different from the normal one (the sinoatrial node). Two main mechanisms exist that may induce ectopic activity: automaticity (generally subdivided into normal and abnormal) and triggered activity. Ectopic activity caused by normal automaticity appears in cardiac cells in which the automaticity (spontaneous generation of electrical impulses) is an intrinsic property. In normal situations, the potential pacemaker activity in cells different from those in the sinoatrial node is inactive because the spontaneous frequency of impulse generation is higher in the sinoatrial node. However, when the frequency of the sinoatrial node decreases below the spontaneous frequency of a subsidiary pacemaker, this pacemaker takes the control of the heart rate and becomes an ectopic focus. Under several pathological situations, any cell in the heart, even those that normally have no spontaneous activity, could become abnormally automatic. Another mechanism for ectopic activity is known as triggered activity, which consists of an impulse (or a train of impulses) provoked by after‐depolarizations, which are abnormal oscillations of the action potential. Two types of after‐depolarizations exist: early (EADs), which appear during the repolarization phase of action potential, and delayed (DADs), which occur when the repolarization phase of the action potential is completed. The main characteristic of the ectopic activity induced by after‐depolarizations is that a previous electrical impulse is necessary to trigger one or more ectopic beats.
Education
Authors: Demir Semahat
Published: April 2006

Biomedical Engineering (BME) education is unique; it is not a traditional education field yet. BME is an interdisciplinary field. BME is the application of engineering and physical sciences into medicine to understand the medical problems and to develop new medical technologies. In detail, BME consists of the basic and clinical applications of biology, chemistry, physics, and mathematics and engineering in medical sciences and life sciences to understand living systems and to provide diagnoses and treatment methods for medical problems.

BME education and training opportunities exist in academia, industry, and government. A formal BME education can be obtained in engineering schools or medical schools. The education can be at the undergraduate level (BS), graduate level (MS, PhD, MD), and post‐doctoral level. The degrees granted in BME are Bachelor of Science (BS), Master of Science (MS), PhD, and medical doctor (MD). Some academic programs can offer dual doctorate (MD/PhD) degrees.
Electrical Safety
Authors: Fernández Chimeno Mireya , Riu Pere J. , Silva Martínez Ferran
Published: April 2006

Electrical safety assessment is mandatory for most electrical equipment in almost all countries. For medical devices, electrical safety is regarded in medical safety standards. There is a broad range of medical devices, so the regulations of different countries (European directives, U.S. Food and Drug Administration (FDA) regulations, etc.) provide a classification of medical devices based on the risk. The medical safety assessment depth depends on the equipment class. Many medical devices safety standards in different countries are usually based on the IEC
60601 family standards, so more or less the tests for safety assessment are the same everywhere. In this article, after a brief revision of the effects of electrical current in the human body, we describe the classification of medical devices in Europe (from the medical devices European directives) and in United States (from the FDA). Finally, some IEC 60601 electrical safety topics are explained.
Electrodes
Authors: Aubert André E. , Beckers Frank , Verheyden Bant , van de Voorde Paul
Published: April 2006

Electrodes are the interface between an energy source (electrical stimulator) and tissue (place where the stimulus has to be delivered). Electrode technology is a vast and difficult domain; it involves aspects of material science, biocompatibility, design techniques for geometry and implantation, fixation at tissue layers, electro‐chemical reactions, physiology, cardiology, and all other body functions prone to be stimulated. All these aspects are briefly presented in this article. Biocompatibility and materials will be discussed related to electrodes, as this topic is also covered in other articles of this encyclopedia. Basically, electrodes are used externally (applied to the skin) as well as internally. Electrical stimulation is used for many functions. The major applications are in cardiology, for pain relief, for treatment of Parkinson's disease, for treatment of incontinence, and for gastroparesis. Cardiac applications will be highlighted more in this article.

Physiological, geometrical, and physical constraints must all be considered by bioengineers and medical doctors, thus leading to optimal sensing, stimulation, adequate thresholds, and long‐term behavior after chronic clinical implantation.
Electrogastrography (EGG)
Authors: Lin Zhiyue , Chen J.D.Z.
Published: April 2006

Electrogastrography (EGG) is a noninvasive technique for the cutaneous recording of gastric myoelectrical activity. Since the first measurement of the electrogastrogram (EGG), a great deal of research has investigated its validation, interpretation, and application. Recently, EGG has received more and more attention. EGG has become an attractive tool to study the electrophysiology of the stomach and pathophysiology of gastric motility disorders. It is currently used in both research settings and clinical settings. The following areas are discussed: the refined methods of EGG, the advanced techniques for processing and analyzing the EGG, and the physiological and clinical applications of EGG.
Event‐Related Potentials
Authors: Bressler Steven L. , Ding Mingzhou
Published: April 2006

It has long been known that the living brains of humans and other mammals generate macroscopic electromagnetic activity that can be recorded from both within and outside the head. From the earliest days of recording this activity, researchers have sought to understand its relation to brain function and to use it to monitor and assess brain state. Continuous records of brain activity, examined without regard to particular points in time, are often useful for determining brain state. However, more detailed knowledge of brain function depends on precise temporal registration of the activity to specific events, either in the external environment or self‐generated. The Event‐Related Potential (ERP) is a temporal signature of macroscopic brain electrical activity related to a sensory, motor, or cognitive event. The Event‐Related Field (ERF) is the magnetic correlate of this activity.
Evolutionary Algorithms
Authors: Repperger Daniel W.
Published: April 2006

A brief tutorial on evolutionary algorithms (EAs) is presented. It is demonstrated that such methods are useful for solving certain complex optimization problems and are more general than traditional techniques. There are many possible applications of this procedure within the context of biomedical engineering, and one is presented here with the goal of improving the design of a human–machine interface. The power in this approach is that many different types of variables can be simultaneously optimized, and new solutions develop using the EA methods that may not be found by conventional methods. The objective function to be optimized can be complex when EAs are used, which makes this approach more applicable to systems that occur in nature, which cannot be simply described in terms of linear equations and convex objective functions.
Exercise Hyperpnea
Authors: Ward Susan A.
Published: April 2006

Control schemes of ventilationduring moderate exercise [i.e., below the lactate threshold (θL)] have classically incorporated both proportional humoral feedback (carotid and central chemoreflex) and neurogenic feed forward (central command, muscle, cardiocirculatory) to provide stability of arterial PCO2(PaCO2) pH (pHa), and PO2(PaO2). In response to a step work‐rate (WR) forcing from prior rest in the upright posture,increases abruptly for some 15–20 s, this being followed by a subsequent more‐prominent exponential component (consistent with first‐order kinetics). The lack of any sustained error signals in the mean levels of PaCO2, pHa, or PaO2, coupled with the dynamic matching ofwith pulmonary CO2outputbut not O2uptake or WR, suggests that the controller operates as if it incorporates an errorless humoral feedback element proportional to(or some close proxy). In addition, thecontroller seems to evidence considerable redundancy, with particular sensory deficits having little effect on the steady‐stateresponse to exercise or the stability of PaCO2between rest and exercise. AboveθL,kinetics become markedly nonlinear, with steady states being either delayed or not attained, which reflects the influence of the developing metabolic acidemia (1) indirectly, via bicarbonate‐mediated body CO2stores washout, which augments; and (2) directly, to effect respiratory compensation for the falling pHa (this being constrained by the falling PaCO2that results fromincreasing out of proportion to). The carotid bodies are important in mediating this respiratory compensation, although with surprisingly slow kinetics, In conclusion, despite there now being general agreement regarding the overall characteristics of theresponse to exercise, the precise details of the control process(es) remain unresolved.
Exercise Physiology
Authors: Whipp Brian J.
Published: April 2006

Exercise intolerance occurs when a person cannot sustain a required work rate sufficiently long for the successful completion of the task. The ability to sustain an exercise task depends largely on the ability to transport oxygen to its utilization site as the terminal oxidant of the mitochondrial electron transport chain in skeletal muscle, and to clear the resulting metabolically produced carbon dioxide and lactic acid. This process requires the kinetics of the associated ventilatory, pulmonary gas exchange, and cardiovascular system responses to be closely coordinated with the intramuscular requirements for ATP utilization and resynthesis. As the kinetic features of these system responses are highly intensity dependent, any meaningful interpretational frame of reference has to provide a rigorous definition of exercise intensity that takes into account individual differences in the threshold for blood lactate increase relative to maximal aerobic capacity. This article provides an introduction to the fundamentals of normal operation of these systems and their integrated patterns of response to particular stress profiles.
Flow Measurement
Authors: Fontaine Arnold A. , Deutsch Steven , Manning Keefe B.
Published: April 2006

Fluid flow occurs throughout biomedical engineering ranging from air flow in the lungs to diffusion of nutrients through membranes and involves bothin vivoandin vitromeasurements. Flows involve fluid media in the form of gas, liquid, or multiphase flows of liquids and gas together or in combination with solid matter. They can involve relatively benign flows like that of saline through an intravenous tube to a biochemically active flow of a nonNewtonian fluid such as blood. Many biomedical or bioengineering processes require the quantification of some flow field that may be directly or indirectly related to the process. Such quantification can involve the measurement of volume or mass flow, the static and dynamic pressures, the local velocity of the fluid, the motion (speed and direction) of particles such as cells, the flow‐related shear, or the diffusion of a chemical species.