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PubMed2006

Biomanufacturing: a US-China National Science Foundation-sponsored workshop.

A recent US-China National Science Foundation-sponsored workshop on biomanufacturing reviewed the state-of-the-art of an array of new technologies for producing scaffolds for tissue engineering, providing precision multi-scale control of material, architecture, and cells. One broad category of such techniques has been termed solid freeform fabrication. The techniques in this category include: stereolithography, selected laser sintering, single- and multiple-nozzle deposition and fused deposition modeling, and three-dimensional printing. The precise and repetitive placement of material and cells in a three-dimensional construct at the micrometer length scale demands computer control. These novel computer-controlled scaffold production techniques, when coupled with computer-based imaging and structural modeling methods for the production of the templates for the scaffolds, define an emerging field of computer-aided tissue engineering. In formulating the questions that remain to be answered and discussing the knowledge required to further advance the field, the Workshop provided a basis for recommendations for future work.

Biocompatible Materials↗
PubMed2001

A biomechanical analysis of an engineered cell-scaffold implant for cartilage repair.

This study evaluated the biomechanical and physical properties of newly formed cartilage engineered from isolated chondrocytes in combination with matrix components. Four groups of constructs were studied. Group A consisted of lyophilized articular cartilage chips mixed with a cell-fibrinogen solution and thrombin to obtain constructs made of fibrin glue, chondrocytes, and cartilage chips. Group B constructs were prepared using fibrin glue and cartilage chips without cells. Group C contained chondrocytes in fibrin glue without chips, and group D comprised constructs of fibrin glue alone. Specimens were implanted in the subcutaneous tissue of nude mice for 9 weeks. At necropsy the specimens were examined grossly, physically, biomechanically, and histologically. The original, preimplantation mass of the constructs was retained only in experimental group A. Histological analysis of specimens in experimental groups A and C demonstrated the presence of newly formed cartilaginous matrix, whereas only fibrotic tissue was observed in control groups B and D. Biomechanical analysis demonstrated higher mean values of equilibrium modulus in the experimental samples of group A with respect to all control groups. This study demonstrated that adding lyophilized cartilage chips to a fibrin glue-engineered cartilage construct maintains the biomechanical properties and the original mass after medium-/long-term in vivo transplantation.

Animals↗
PubMedDate not supplied

The definition of a clinical engineer.

The American College of Clinical Engineering formed a committee to develop a contemporary definition of a Clinical Engineer. The committee considered existing definitions including that currently used by the Clinical Engineering Board of Examiners of the International Certification Commission. Educators and other societies provided other definitions. Following substantial discussion and revisions, the definition was adopted by the Board of Directors of the ACCE on May 13, 1991.

Biomedical Engineering↗
PubMed2002

In vitro systems for tissue engineering.

Tissue engineering, by necessity, encompasses a wide array of experimental directions and scientific disciplines. In vitro tissue engineering involves the manipulation of cells in vitro, prior to implantation into the in vivo environment. In contrast, in vivo tissue engineering relies on the body's natural ability to regenerate over non-cell-seeded biomaterials. Cells, biomaterials, and controlled incubation conditions all play important roles in the construction and use of modern in vitro systems for tissue engineering. Gene delivery is also an important factor for controlling or supporting the function of engineered cells both in vitro and post implantation, where appropriate. In this review, systems involved in the context of in vitro tissue engineering are addressed, including bioreactors, cell-seeded constructs, cell encapsulation, and gene delivery. Emphasis is placed upon investigations that are more directly linked to the treatment of clinical conditions.

Animals↗
PubMed1999

Functional arteries grown in vitro.

A tissue engineering approach was developed to produce arbitrary lengths of vascular graft material from smooth muscle and endothelial cells that were derived from a biopsy of vascular tissue. Bovine vessels cultured under pulsatile conditions had rupture strengths greater than 2000 millimeters of mercury, suture retention strengths of up to 90 grams, and collagen contents of up to 50 percent. Cultured vessels also showed contractile responses to pharmacological agents and contained smooth muscle cells that displayed markers of differentiation such as calponin and myosin heavy chains. Tissue-engineered arteries were implanted in miniature swine, with patency documented up to 24 days by digital angiography.

Animals↗
PubMed1999

Engineering aspects of hyperthermia therapy.

The continuing accrual of positive results in clinical cancer trials of adjunctive, synergistic hyperthermia therapy remains a strong motivation for the development of improved hyperthermia equipment and software. Indeed, the lack of needed engineering tools can be viewed as the major stumbling block to hyperthermia's effective clinical implementation. Developing clinically effective systems will be difficult, however, because (a) it requires solving several complex engineering problems, for which (b) setting appropriate design and evaluation goals is currently difficult owing to a lack of critical biological, physiological, and clinical knowledge, two tasks which must (c) be accomplished within a complicated social/political structure.

Biomedical Engineering↗
PubMedDate not supplied

Bioengineering at the University of Strathclyde.

Bioengineering is, of course, no longer regarded as 'new'. Many groups exist in many centres in the UK and worldwide. The writer considers himself particularly fortunate in having been involved since 1960 in bioengineering research, teaching and development following a very satisfying period as a lecturer in mechanics for engineering students. On hindsight, the most important feature has been the pleasure of association with a succession of talented, intelligent and strongly motivated academic colleagues and students devoted to research and development in the field of bioengineering.

Biomedical Engineering↗
PubMed1993

Control engineering for planning drug therapy.

An optimal drug input may be defined as producing an ideal therapeutic effect as closely as possible without exceeding predetermined safety limits on any adverse drug effects. The intensity and time patterns of the drug-elicited response are functions of the pharmacodynamic properties of the drug in the patient. Drug input optimisation can be considered as a control problem and the different control engineering techniques may serve to assist in planning/implementing drug dosage regimens. This paper reviews some problems associated with planning optimal drug therapy in different clinical context and illustrates the solution of such problems by clinical examples.

Biomedical Engineering↗
PubMedDate not supplied

Occupational biohazards affecting clinical engineers & BMETs. Part II: Common biohazard questions.

Worldwide concern about AIDS has prompted concern over the prevention of, and protection from, a variety of biological hazards. Healthcare workers are at greater risk for contracting and/or transmitting certain types of contagious disease organisms because of the nature and environment of their work. In response to requests from BMETs, the author developed an educational presentation on work-related biohazards. This article, the second in a five-part series, addresses some questions commonly raised by more than 300 biomedical personnel who have attended the presentation. Recommendations are also made to help BMETs and CEs avoid occupationally acquired illnesses.

Biomedical Engineering↗
PubMed2000

Bioglass 45S5 stimulates osteoblast turnover and enhances bone formation In vitro: implications and applications for bone tissue engineering.

We investigated the concept of using bioactive substrates as templates for in vitro synthesis of bone tissue for transplantation by assessing the osteogenic potential of a melt-derived bioactive glass ceramic (Bioglass 45S5) in vitro. Bioactive glass ceramic and bioinert (plastic) substrates were seeded with human primary osteoblasts and evaluated after 2, 6, and 12 days. Flow cytometric analysis of the cell cycle suggested that the bioactive glass-ceramic substrate induced osteoblast proliferation, as indicated by increased cell populations in both S (DNA synthesis) and G2/M (mitosis) phases of the cell cycle. Biochemical analysis of the osteoblast differentiation markers alkaline phosphatase (ALP) and osteocalcin indicated that the bioactive glass-ceramic substrate augmented osteoblast commitment and selection of a mature osteoblastic phenotype. Scanning electron microscopic observations of discrete bone nodules over the surface of the bioactive material, from day 6 onward, further supported this notion. A combination of fluorescence, confocal, transmission electron microscopy, and X-ray microprobe (SEM-EDAX) examinations revealed that the nodules were made of cell aggregates which produced mineralized collagenous matrix. Control substrates did not exhibit mineralized nodule formation at any point studied up to 12 days. In conclusion, this study shows that Bioglass 45S5 has the ability to stimulate the growth and osteogenic differentiation of human primary osteoblasts. These findings have potential applications for tissue engineering where this bioactive glass substrate could be used as a template for the formation of bioengineered bone tissue.

Alkaline Phosphatase↗
PubMedDate not supplied

Equipment management risk rating system based on engineering endpoints.

The equipment management risk ratings system outlined here offers two significant departures from current practice: risk classifications are based on intrinsic device risks, and the risk rating system is based on engineering endpoints. Intrinsic device risks are categorized as physical, clinical and technical, and these flow from the incoming equipment assessment process. Engineering risk management is based on verification of engineering endpoints such as clinical measurements or energy delivery. This practice eliminates the ambiguity associated with ranking risk in terms of physiologic and higher-level outcome endpoints such as no significant hazards, low significance, injury, or mortality.

Biomedical Engineering↗
PubMedDate not supplied

Justifying and tracking BMET training.

We have outlined the importance of BMET training and how it is a crucial investment for not only the health care facility but also clinical engineering and individual BMETs. Training methods and funding mechanisms are also important aspects of the continuing education process. Being aware of the alternatives helps to achieve the goals of the clinical engineering program. We have also demonstrated management techniques of acquiring training, evaluating courses, and keeping statistics. Courstat manages statistics of training intensity among BMETs. This kind of tool provides managers with an overall picture of departmental expertise.

Biomedical Engineering↗
PubMed2006

Cytochromes P450 as versatile biocatalysts.

Cytochromes P450 are ubiquitously distributed enzymes, which were discovered about 50 years ago and which possess high complexity and display a broad field of activity. They are hemoproteins encoded by a superfamily of genes converting a broad variety of substrates and catalysing a variety of interesting chemical reactions. This enzyme family is involved in the biotransformation of drugs, the bioconversion of xenobiotics, the metabolism of chemical carcinogens, the biosynthesis of physiologically important compounds such as steroids, fatty acids, eicosanoids, fat-soluble vitamins, bile acids, the conversion of alkanes, terpenes, and aromatic compounds as well as the degradation of herbicides and insecticides. There is also a broad versatility of reactions catalysed by cytochromes P450 such as carbon hydroxylation, heteroatom oxygenation, dealkylation, epoxidation, aromatic hydroxylation, reduction, dehalogenation (Sono, M., Roach, M.P., Coulter, E.D., Dawson, J.H., 1996. Heme-containing oxygenases. Chem. Rev. 96, 2841-2888), (Werck-Reichhart, D., Feyereisen, R., 2000. Cytochromes P450: a success story. Genome Biol. 1 (REVIEWS3003)), (Bernhardt, R., 2004. Cytochrome P-450. Encyclopedia Biol. Chem. 1, 544-549), (Bernhardt, R., 2004. Optimized chimeragenesis; creating diverse P450 functions. Chem. Biol. 11, 287-288), (Guengerich, F.P., 2004. Cytochrome P450: what have we learned and what are the future issues? Drug Metab. Rev. 36, 159-197). More than 5000 different P450 genes have been cloned up to date (for details see: ). Members of the same gene family are defined as usually having > or =40% sequence identity to a P450 protein from any other family. Mammalian sequences within the same subfamily are always >55% identical. The numbers of individual P450 enzymes in different species differ significantly, showing the highest numbers observed so far in plants. The structure-function relationships of cytochromes P450 are far from being well understood and their catalytic power has so far hardly been used for biotechnological processes. Nevertheless, the set of interesting reactions being catalysed by these systems and the availability of new genetic engineering techniques allowing to heterologously express them and to improve and change their activity, stability and selectivity as well as the increasing interest of the industry in life sciences makes them promising candidates for biotechnological application in the future.

Animals↗
PubMed2004

Some new directions in control theory inspired by systems biology.

This paper, addressed primarily to engineers and mathematicians with an interest in control theory, argues that entirely new theoretical problems arise naturally when addressing questions in the field of systems biology. Examples from the author's recent work are used to illustrate this point.

Biomedical Engineering↗
PubMed1998

Tissue engineered neocartilage using plasma derived polymer substrates and chondrocytes.

This study demonstrates that fibrin monomers can be polymerized into moldable gels and used for the encapsulation of isolated chondrocytes. This biologically derived scaffold will maintain three-dimensional spatial support, allowing new tissue development in a subcutaneous space. Chondrocytes isolated from the glenohumeral and humeroradioulnar joints of a calf were combined with cyroprecipitate and polymerized with bovine thrombin to create a fibrin glue gel with a final cell density of 12.5 x 10(6) cells/ml. The polymer-chondrocyte constructs were implanted subcutaneously in 12 nude mice and incubated for 6 and 12 weeks in vivo. Histologic and biochemical analysis including deoxyribonucleic acid (DNA) and glycosaminoglycan quantitation confirmed the presence of actively proliferating chondrocytes with production of a well-formed cartilaginous matrix in the transplanted samples. Control specimens from 12 implantation sites consisting of chondrocytes alone or fibrin glue substrates did not demonstrate any gross or histologic evidence of neocartilage formation. Moldable autogenous fibrin glue polymer systems have a potential to serve as alternatives to current proprietary polymer systems used for tissue engineering cartilage as well as autogenous grafts and alloplastic materials used for facial skeletal and soft-tissue augmentation.

Animals↗
PubMed1997

Engineering a concept: the creation of tissue engineering.

Tissue engineering is a fashionable phrase and a new concept. This article analyses what is meant by this term and discusses some of the products that may emerge from the translation of this concept into clinical reality.

Artificial Organs↗
PubMed2005

'Healthcare Estates' to focus on reforms. Harrogate International Centre, 1-2 November 2005.

The Institute of Healthcare Engineering and Estate Management's (IHEEM) Healthcare Estates Conference and Exhibition is the leading national event for professionals in the field of estate planning, facilities management and healthcare engineering. According to IHEEM president Richard Nugent, the time is now right for estates and facilities professionals to seize the "once in a lifetime" opportunity to play their part increating a health service with facilities that are the envy of the world.

Biomedical Engineering↗
PubMedDate not supplied

Cardiac pacing--from then to now.

Progress in both the health sciences and engineering sciences has been necessary for the development of the cardiac pacemaker. From the invention of the vacuum tube triode amplifier in 1906 to that of the oscillator just a few years later; from the early electrocardiograph in 1906 and the first stimulation of a dog's heart in 1927 to the application of electricity to the heart of a stillborn infant only 2 years later, engineering and medicine have progressed together to solve problems in pacemakers. The semiconductor transistor emerged in 1948, and in 1950 work was published on the open heart resuscitation of dogs with voltage pulses to the heart, work whose principle was applied soon after in a human patient with complete heart block. The development of the modern pacemaker has run an exciting course, including such phenomena as one engineer helping to design his own pacemaker. In the past 20 years, science has change the package, the power source, pacing mode, electrodes, and leads of pacemakers; it has improved their reliability and longevity, their programming, telemetry, and instrumentation.

Biomedical Engineering↗

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