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Intelligently exploiting the material properties of polymers can lead to multifunctional components that are commercially and functionally superior to previous designs. This article explains how to achieve this.
Recent developments in biomedical informatics research have afforded possibilities for great advances in health care delivery. These exciting opportunities also present a number of challenges to the implementation and integration of technologies in the workplace. As in most domains, there is a gulf between technologic artifacts and end users, which compromises the culture of safety in the workplace. Because clinical practice is a human endeavor, there is a need for bridging disciplines to enable clinicians to benefit from rapid technologic advances. This, in turn, necessitates a broadening of disciplinary boundaries to consider cognitive and social factors related to the design and use of technology. The authors argue for a place of prominence for cognitive science in understanding nursing factors associated with patient safety. Cognitive science provides a framework for the analysis and modeling of complex human performance. Studies of clinical cognition can meaningfully inform and shape design, development and assessment of information systems. Furthermore, they have a decisive impact on whether information technology has a positive influence on human performance and are especially important in understanding and promoting safe practices. These issues are discussed in the context of clinical informatics with a focus on nursing practice.
Reports bear witness that a significant proportion of all healthcare equipment in developing countries is not in use. There are many and varied reasons this, including inappropriateness or a lack of basic maintenance. This report addresses these issues, including guidelines for procurement staff and end-users and a bibliography. Examples of the considerations involved are given in the specialties of therapy oxygenation, laboratory tests and solar-powered equipment.
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The RADIUS study opened up controversial discussions of the applications of ultrasound technology in patient management, screening, and outcomes analysis. Advances in technology may ultimately resolve national policy issues.
Better communication between physicians and manufacturers of medical devices is becoming increasingly important due to wider usage of these devices, as well as more intense scrutiny by consumer interest groups. Physicians should therefore have more complete knowledge of techniques of new product development. A new product typically passes through at least six stages, as follows: (1) idea conception; (2) merit and feasibility study; (3) design and testing; (4) production preparation; (5) market preparation; and (6) marketing. These steps are completed over a period of several years at an ever increasing cost. We propose that interaction procedures be undertaken so as to enhance direct physician-manufacturer communications in the medical device arena. Some possible techniques of improving these communications include the direct training of physicians and manufacturers in each other's problems, the establishment of hospital engineering groups, the placement of medical consultants in industry, and the active participation in device standards-generating groups and other groups of mutual interest.
New tissue engineering technologies will rely on biomaterials that physically support tissue growth and stimulate specific cell functions. The goal of this study was to create a biomaterial that combines inherent biological properties which can specifically trigger desired cellular responses (e.g., angiogenesis) with electrical properties which have been shown to improve the regeneration of several tissues including bone and nerve. To this end, composites of the biologically active polysaccharide hyaluronic acid (HA) and the electrically conducting polymer polypyrrole (PP) were synthesized and characterized. Electrical conductivity of the composite biomaterial (PP/HA) was measured by a four-point probe technique, scanning electron microscopy was used to characterize surface topography, X-ray photoelectron spectroscopy and reflectance infrared spectroscopy were used to evaluate surface and bulk chemistry, and an assay with biotinylated hyaluronic acid binding protein was used to determine surface HA content. PP/HA materials were also evaluated for in vitro cell compatibility and tissue response in rats. Smooth, conductive, HA-containing PP films were produced; these films retained HA on their surfaces for several days in vitro and promoted vascularization in vivo. PP/HA composite biomaterials are promising candidates for tissue engineering and wound-healing applications that may benefit from both electrical stimulation and enhanced vascularization.
Global gene regulation throughout the Escherichia coli stress response to overexpression of each of five recombinant proteins was evaluated. Reverse-transcriptase polymerase chain reaction-amplified mRNA from induced and control cells were hybridized with a DNA array of Kohara clones representing 16% (700 genes) of the E. coli genome. Subsequently, Northern analysis was performed for quantification of specific gene dynamics and statistically significant overlap in the regulation of 11 stress-related genes was found using correlation analysis. The results reported here establish that there are dramatic changes in the transcription rates of a broad range of stress genes (representing multiple regulons) after induction of recombinant protein. Specifically, the responses included significantly increased upregulation of heat shock (ftsH, clpP, lon, ompT, degP, groEL, aceA, ibpA), SOS/DNA damage (recA, lon, IS5 transposase), stationary phase (rpoS, aceA), and bacteriophage life cycle (ftsH, recA) genes. Importantly, similarities at the microscopic (gene) level were not clearly reflected at the macroscopic (growth rate, lysis) level. The use of such dynamic data is critical to the design of gene-based sensors, the engineering of metabolic pathways, and the determination of parameters (harvest and induction times) needed for successful recombinant E. coli fermentations.
This paper reviews three areas of the author's research. The first area concerns the development of technologies to release macromolecules continuously from solid polymers. By embedding solid protein (or other macromolecule) powders at the correct concentration in hydrophobic polymers, prolonged release for over 100 days can be achieved. The second area involves the synthesis of new biodegradable polymers specifically designed for drug delivery. A novel family of polymers, polyanhydrides, now being explored in a number of medical applications is examined. The use of these polymers to deliver chemotherapeutic agents locally may provide a new approach to treat brain cancer. The final research topic is in the area of tissue engineering. By placing mammalian cells on biodegradable polymer scaffolds, a variety of tissues have been created in animal models. Cartilage is discussed as a model tissue.
OBJECTIVE: In tissue engineering, three-dimensional biodegradable scaffolds are generally used as a basic structure for cell anchorage, cell proliferation and cell differentiation. The currently used biodegradable scaffolds in cardiovascular tissue engineering are potentially immunogenic, they show toxic degradation and inflammatory reactions. The aim of this study is to establish a new three-dimensional cell culture system within cells achieve uniform distribution and quick tissue development and with no toxic degradation or inflammatory reactions. METHODS: Human aortic tissue is harvested from the ascending aorta in the operation room and worked up to pure human myofibroblasts cultures. These human myofibroblasts cultures are suspended in fibrinogen solution and seeded into 6-well culture plates for cell development for 4 weeks and supplemented with different concentrations of aprotinin. Hydroxyproline assay and histological studies were performed to evaluate the tissue development in these fibrin gel structures. RESULTS: The light microscopy and the transmission electron microscopy studies for tissue development based on the three-dimensional fibrin gel structures showed homogenous cell growth and confluent collagen production. No toxic degradation or inflammatory reactions could be detected. Furthermore, fibrin gel myofibroblasts structures dissolved within 2 days in medium without aprotinin, but medium supplemented with higher concentration of aprotinin retained the three-dimensional structure and had a higher collagen content (P<0.005) and a better tissue development. CONCLUSIONS: A three-dimensional fibrin gel structure can serve as a useful scaffold for tissue engineering with controlled degradation, excellent seeding effects and good tissue development.
The field of neuroscience has always been attractive to engineers. Neurons and their connections, like tiny circuit elements, process and transmit information in a dramatic way that is intimately curious to researchers in the computer science and engineering fields. Of particular interest has been the recent push in applying microtechnology to the field of neuroscience. This review is meant to provide an overview of some of the subtle nuances of the nervous system and outline recent advances in lab on a chip applications in neurobiology. It also aims to highlight some of the challenges the field faces in the hopes of encouraging new engineering researchers to collaborate with neurobiologists to help advance our basic understanding of the nervous system and create novel applications based on neuroengineering principles.
Morphogenesis is the developmental cascade of pattern formation, body plan establishment, and the architecture of mirror-image bilateral symmetry of many structures and asymmetry of some, culminating in the adult form. Tissue engineering is the emerging discipline of design and construction of spare parts for the human body to restore function based on principles of molecular developmental biology and morphogenesis governed by bioengineering. The three key ingredients for both morphogenesis and tissue engineering are inductive signals, responding stem cells, and the extracellular matrix. Among the many tissues in the human body, bone has considerable powers for regeneration and is a prototype model for tissue engineering based on morphogenesis. Implantation of demineralized bone matrix into subcutaneous sites results in local bone induction. This model mimics sequential limb morphogenesis and permitted the isolation of bone morphogens. Although it is traditional to study morphogenetic signals in embryos, bone morphogenetic proteins (BMPs), the inductive signals for bone, were isolated from demineralized bone matrix from adults. BMPs and related cartilage-derived morphogenetic proteins (CDMPs) initiate, promote, and maintain chondrogenesis and osteogenesis and have actions beyond bone. The symbiosis of bone inductive and conductive strategies are critical for tissue engineering, and is in turn governed by the context and biomechanics. The context is the microenvironment, consisting of extracellular matrix, which can be duplicated by biomimetic biomaterials such as collagens, hydroxyapatite, proteoglycans, and cell adhesion proteins including fibronectins. Thus, the rules of architecture for tissue engineering are an imitation of the laws of developmental biology and morphogenesis, and thus may be universal for all tissues, including bones and joints.
The psychophysical aspects of the color experience and the clinical significance of color during video endoscopy are introduced in this paper. This introduction includes a description of how colors are rendered in video endoscope systems along with basic colorimetry, the science of color. Together these provide the clinical engineer with an understanding of color and a method of effectively communicating color information. The ability to standardize color rendition in video endoscopy systems is not yet available. Nonetheless, an argument is presented in favor of the clinical engineer normalizing color rendition in video endoscope systems in the hospital and educating the clinicians on managing endoscopic system color performance in the clinical setting.
The apparatus described in this communication enables the force-velocity relationship to be determined for whole rabbit muscles in vivo and their resistance to fatigue to be assessed at specified rates of external work. The ergometer generates constant-velocity motion, controlling a force of up to 50 N, over a range of velocity up to 500 mm/s and a distance of 20 mm. This distance corresponds to the range of shortening of the rabbit tibialis anterior muscle from full plantar flexion to full dorsiflexion of the foot, equivalent to approximately 28% fiber shortening. Activated muscles can be allowed to shorten at constant velocity from any point on their isometric force trajectory. Cyclic releases for fatigue testing can be made at rates up to 30 releases/min over a period of 6-8 h. The timing of the release and return strokes of the ergometer is under the control of a digital programmer that also synchronizes the delivery of activating stimuli to the muscle nerve and trigger signals to the recording equipment. An electrohydraulic design was chosen because it is simpler to engineer than an electromagnetic actuator, is reliable in continuous cyclic use, and can be assembled, at least in part, from available industrial components.
Work on cochlear prostheses for the auditory rehabilitation of the profoundly deaf represents a challenging problem. Some early, but perhaps premature, surgical attempts have helped to bring the entire issue into focus. Systemic studies are now under way in many different places. Although the purely engineering problems as well as the surgical ones appear solvable at this time, the remaining unsolved problems lie in two areas: 1) the bioengineering interfacing, i.e., the search for methods needed to connect an engineering (electronic) device to the neural auditory system in an efficient manner; and 2) clinical tests for the assessment of the functional state of the cochlear nerve.
The engineering of a functional blood vessel substitute has for a quarter of a century been a "holy grail" within the cardiovascular research community. Such a substitute must exhibit long term patency, and the critical issues in this area in many ways are influenced by biomechanics. One of the requirements is that it must be non-thrombogenic, which requires an "endothelial-like" inner lining. It also must have mechanical strength, i.e. a burst pressure, sufficient to operate at arterial pressures. Ideally, however, it must be more than this. It also must have viscoelastic properties that match those of the native vessel being replaced. Finally, if it is to be able to adapt to changing blood flow conditions, it must exhibit vasoactivity, a function which in and of itself can be viewed as biomechanical in nature. To achieve this requires having, as part of the construct, vascular smooth muscle cells, which are contractile in nature and oriented in a circumferential direction. Only if an engineered blood vessel substitute possesses all of these functional characteristics, can one say that the functionality exhibited by a native vessel is being mimicked.
As the Agenda for Change unfolds, several major changes will take place. Organizations seeking accreditation will face potentially greater pressure to improve as accreditation and performance data become more available to the public and payers. Future accreditation decisions will be based more on observed, demonstrated, and measured performance than on statements of policy and practice. Key to this in the survey process are the new unit-based survey and the use of indicators. Finally, accreditation evaluation activities provided by the Joint Commission will become a more persistent part of the life of accredited organizations. New activities will include an annual contact to update demographic information, the random, unannounced survey process, and frequent data and information exchanges based on the indicator database. The goal of these changes is to get closer to the real work of patient care through measurement and assessment of organizational competence, performance, and ability to change. The challenge facing clinical engineers as equipment or technology managers is to extend their vision of the equipment management process beyond the engineering needs of medical equipment. The key focus of the new Joint Commission standards and accreditation process is the acquisition and use of information. Equipment, as it becomes more complex, requires more user knowledge to be applied effectively. As part of the information highway, the clinical engineer of tomorrow must focus on the information content of the equipment being introduced and determine the most effective method of transferring the information into user "brainwave."
Bone marrow stromal cells (BMSC) are pluripotent progenitor cells that can regenerate different skeletal tissues in response to environmental signals. In this study, we used highly porous, structurally stable three-dimensional polymer foams in conjunction with specific regulatory molecules to selectively differentiate mammalian BMSC into either cartilaginous or bone-like tissues. Bovine BMSC were expanded in monolayers and cultured on 5-mm-diameter, 2-mm-thick foams made of poly(lactic-co-glycolic acid) and poly(ethylene glycol). Constructs maintained their original size and shape for up to 4 weeks of culture and supported BMSC growth and production of extracellular matrix (ECM). By proper use of chondrogenic (dexamethasone, insulin, transforming growth factor-beta1) or osteogenic (dexamethasone, beta-glycerophosphate) medium supplements, we could control whether the generated ECM was cartilaginous (containing collagen type II and sulfated glycosaminoglycans) or bone-like (containing osteocalcin, osteonectin, and mineralized foci). After 4 weeks of cultivation, cartilaginous and bone-like ECM were uniformly distributed throughout the construct volume and respectively represented 34.2 +/- 9.3% and 12.6 +/- 3.2% of the total available area. BMSC culture on poly(lactic-co-glycolic acid)/poly(ethylene glycol) foams provides a three-dimensional model system to study the development of mesenchymal tissues in vitro and has potential applications in engineering autologous grafts for skeletal tissue repair.