Some aspects of medical ethics from the perspective of bioengineering.
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Out of a number of important methods used in laboratory angiology, only a limited group was selected to be discussed in this symposium. Phonoangiography is reviewed from the qualitative and quantitative viewpoint for its practical value and accessibility. Various aspects of pressure and volume detection of the eye pulse are discussed from the viewpoint of carotid artery disease and its noninvasive diagnosis, with special reference to oculoplethysmography as well as the Gee-pneumooculoplethysmography. Impedance plethysmography (IPG) is one of the controversial techniques used in laboratory angiology, with its main application currently in the area of diagnosis of venous obstructive disease. The dilemma of application of IPG in the diagnosis of arterial disease is discussed mainly from an engineering point of view. Spectral analysis will be covered in view of the fast emergence of Doppler Duplex scanning as the major diagnostic mode in extracranial carotid artery disease.
BACKGROUND: This paper cites the development of the principles of photoelastic stress analysis, contemporary to the life of Samuel Haughton. Subsequent studies of bone and joint replacements are discussed, with reference to hypotheses regarding bone, including the coincidence of trabecular structure with principal stresses. Issues regarding assumptions of homogeneous and isotropic properties in photoelastic modelling are acknowledged. AIM: Awareness of photoelastic methods is often through the visual appeal of the coloured fringe patterns. The aim of this paper is to complement this awareness by demonstration of the quantitative analyses that may be conducted through biomechanical examples. METHODS: Examples of new pseudo three-dimensional model analyses are presented together with a method for photoelastic study of cancellous bone, which entails novel procedures for preparation of replicate models and for optical evaluation of fringes. CONCLUSION: Photoelastic analysis offers novel solutions to studies in biomechanics, which are facilitated by contemporary modelling materials.
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Over 30 000 patients die annually in the United States from liver failure. In fulminant hepatic failure, a clinical syndrome associated with high mortality, orthotopic liver transplantation is the primary therapeutic option for patients not responding to supportive therapy. However, the persistent scarcity of donor organs has limited this therapeutic modality, resulting in a continued increase in the number of patients who die waiting for a donor liver. An extracorporeal bioartificial liver device could provide vital support to a liver failure patient until a donor liver was available or until the patient's own liver regenerated. Although it is unclear which liver-specific functions must be provided by such a device to be effective, a constant challenge has been to obtain stable, well-differentiated, and normally functioning hepatocytes that can be cultured at high cell densities. Many of the devices currently undergoing clinical trials are limited by designs which are prone to substrate limitations, resulting in compromised hepatocyte function. In devices that avoid substrate limitations, hepatocyte functions can be optimized, thereby leading to increased device efficiency. In this overview, the authors describe the critical issues involved in bioartificial liver development and discuss their experiences in hepatocyte culture optimization within the context of a microchannel, flat-plate bioartificial liver device with an internal membrane oxygenator.
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A plasmid has been constructed containing the DNA sequences that direct the expression of the aphthovirus RNA-dependent RNA polymerase (virus infection-associated antigen, VIAA) in its native form. The aphthovirus polypeptide was designed to contain only a single additional amino acid, the N-terminal methionine. The recombinant protein has been purified and used in enzyme-linked immunoelectrotransfer blots to detect aphthovirus-specific antibodies in the sera of persistently infected animals. Furthermore, studies were carried out to test the hypothesis that antibodies against other nonstructural antigens appear in the sera of these animals. It was established that antibodies against polypeptides 3A and 3B can serve as complementary markers for late aphthovirus-carrier state detection. The considerable potential of this approach to detect aphthovirus-specific antibodies, when the isolation of infectious virus is not possible, was demonstrated. Negative results were obtained in animals from virus-free areas and in vaccinated cattle. This assay has the added advantage that no infectious or noninfectious virus is involved during antigen production.
Eight boars 11 months of age that were seronegative to pseudorabies virus were trained for hand collection of semen. A genetically engineered pseudorabies virus vaccine was given to 7 of 8 boars, while the eighth was left unvaccinated to serve as a control. Semen samples were collected at 7 day intervals from 42 days prior to vaccination through 49 days after vaccination. Rectal temperatures and general health of the boars were clinically normal throughout the trial, and no clear differences were observed in the quality of semen collected from the boars before or after vaccination. The semen samples were tested for vaccine virus and none was detected.
Through the active transfer of technology, the National Aeronautics and Space Administration (NASA) Technology Utilization (TU) Program assists private companies, associations, and government agencies to make effective use of NASA's technological resources to improve U.S. economic competitiveness and to provide societal benefit. Aerospace technology from areas such as digital image processing, space medicine and biology, microelectronics, optics and electrooptics, and ultrasonic imaging have found many secondary applications in medicine. Examples of technology spinoffs are briefly discussed to illustrate the benefits realized through adaptation of aerospace technology to solve health care problems. Successful implementation of new technologies increasingly requires the collaboration of industry, universities, and government, and the TU Program serves as the liaison to establish such collaborations with NASA. NASA technology is an important resource to support the development of new medical products and techniques that will further advance the quality of health care available in the U.S. and worldwide.