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PubMedDate not supplied

Guidelines for clinical engineering programs--Part I: guidelines for electrical isolation; Part II: performance evaluation of clinical engineering programs.

This series presents guidelines for: electrically isolated inputs and outputs; measuring the performance of hospital biomedical engineering programs; evaluating the risk of electric shock in hospitals; and for isolated power in anesthetizing locations. In Part I, specific recommendations are given for the use of insulated approach, battery-powered monitors in surgery, and for isolation requirements for devices connected to cardiac leads. In Part II, checklists are provided for the self-evaluation of an in-house, biomedical engineering staff. Parts III and IV, in future issues of this Journal, will include discussion of the theoretical electrical hazard potential in reference to the use of isolated power systems. The question of whether isolated power should be required in all anesthetizing locations will be discussed in Part IV.

Accident Prevention↗
PubMed2000

A useful marker for evaluating tissue-engineered products: gap-junctional communication for assessment of the tumor-promoting action and disruption of cell differentiation in tissue-engineered products.

An in vitro system for evaluating the safety of tissue-engineered products is a convenient because of its rapidity and low cost. On the basis of recent studies, intercellular channels called gap-junctions are considered to play an important role on the tumor-promotion stage during the tumorigenesis induced by polyurethanes. Further, we also demonstrate the significance of the intercellular communication during neuronal cell differentiation. From these results, we propose a survey of the function of the gap-junctional communication as a probable useful marker for evaluating the safety of tissue-engineered products.

Animals↗
PubMed2004

Formation of tissue-engineered human auricular cartilage via tissue engineering technique for future use in ear surgery.

To date there is no optimal approach to reconstruct an external ear. However, advances in tissue engineering technologies have indicated that in vitro autologous elastic cartilage might be of great importance in the future treatment of these patients. The aim of this study was to observe monolayer expansion of auricular cartilage and to evaluate engineered cartilage using standard histochemical study.

Cartilage↗
PubMed2006

Effects of Runx2 genetic engineering and in vitro maturation of tissue-engineered constructs on the repair of critical size bone defects.

Genetic and tissue engineering strategies are being pursued to address the clinical limitations of current bone grafting materials. Based on our previous work demonstrating that overexpression of the Runx2 osteoblastic transcription factor and in vitro construct maturation synergistically enhanced in vivo mineralization in an ectopic site (Byers et al., Tissue Eng 2004;10:1757-1766), we examined the effects of these two parameters on the repair of critical size bone defects. Primary rat bone marrow stromal cells transduced with Runx2 or control (no Runx2 insert) retroviral vector were seeded onto 3D fused deposition-modeled polycaprolactone scaffolds. Runx2-modified cells produced biologically-equivalent mineralized matrices at nearly 2-fold higher rates than control cells. Constructs cultured in vitro for 1 day (immature) or 21 days (mineralized) were subsequently implanted into critical size calvaria defects in syngeneic rats, and bone healing was analyzed by micro-CT and histomorphometry at 28 days. Runx2-modified and control constructs precultured for 1 day healed to a greater extent than defects receiving no implant. Cell-free scaffolds yielded equivalent levels of bone formation as constructs precultured for 1 day. Interestingly, defects treated with control cell-seeded constructs precultured for 21 days exhibited low bone formation compared to other construct treatments, and repair was comparable to empty defects. In contrast, Runx2-modified constructs precultured for 21 days contained twice as much bone as control constructs precultured for 21 days and equivalent levels of new bone as cell-free and 1 day precultured constructs. These results demonstrate interplay between Runx2 genetically-modified cells and in vitro construct maturation in bone healing responses.

Absorbable Implants↗
PubMed2006

Engineering controllable anisotropy in electrospun biodegradable nanofibrous scaffolds for musculoskeletal tissue engineering.

Many musculoskeletal tissues exhibit significant anisotropic mechanical properties reflective of a highly oriented underlying extracellular matrix. For tissue engineering, recreating this organization of the native tissue remains a challenge. To address this issue, this study explored the fabrication of biodegradable nanofibrous scaffolds composed of aligned fibers via electrospinning onto a rotating target, and characterized their mechanical anisotropy as a function of the production parameters. The characterization showed that nanofiber organization was dependent on the rotation speed of the target; randomly oriented fibers (33% fiber alignment) were produced on a stationary shaft, whereas highly oriented fibers (94% fiber alignment) were produced when rotation speed was increased to 9.3m/s. Non-aligned scaffolds had an isotropic tensile modulus of 2.1+/-0.4MPa, compared to highly anisotropic scaffolds whose modulus was 11.6+/-3.1MPa in the presumed fiber direction, suggesting that fiber alignment has a profound effect on the mechanical properties of scaffolds. Mechanical anisotropy was most pronounced at higher rotation speeds, with a greater than 33-fold enhancement of the Young's modulus in the fiber direction compared to perpendicular to the fiber direction when the rotation speed reached 8m/s. In cell culture, both the organization of actin filaments of human mesenchymal stem cells and the cellular alignment of meniscal fibroblasts were dictated by the prevailing nanofiber orientation. This study demonstrates that controllable and anisotropic mechanical properties of nanofibrous scaffolds can be achieved by dictating nanofiber organization through intelligent scaffold design.

Absorbable Implants↗
PubMed2005

Challenge-based instruction in biomedical engineering: a scalable method to increase the efficiency and effectiveness of teaching and learning in biomedical engineering.

Vanderbilt University, Northwestern University, the University of Texas and the Harvard/MIT Health Sciences Technology Program have collaborated since 1999 to develop means to improve bioengineering education. This effort, funded by the National Science Foundation as the VaNTH Engineering Research Center in Bioengineering Educational Technologies, has sought a synthesis of learning science, learning technology, assessment and the domains of bioengineering in order to improve learning by bioengineering students. Research has shown that bioengineering educational materials may be designed to emphasize challenges that engage the student and, when coupled with a learning cycle and appropriate technologies, can lead to improvements in instruction.

Biomedical Engineering↗
PubMed2005

Novel ultrasonic evaluation of tissue-engineered cartilage for large osteochondral defects--non-invasive judgment of tissue-engineered cartilage.

Although numerous methods for regenerating articular cartilage have been investigated, the regenerated tissue showed various histological findings from hyaline-like cartilage to fibrous tissue. Without biopsy, we are unable to know whether the cartilage regeneration method was histologically successful or not. We developed a new ultrasonic evaluation system for articular cartilage using the maximum magnitude (MM) from ultrasonic analysis. The purpose of this study was to investigate the usefulness of ultrasonic judgment of the cartilage regeneration procedure. Using our system we quantitatively evaluated tissue-engineered cartilage in rabbit cartilage defects. The specimens were retrospectively divided into two groups on the basis of histological findings and investigated whether significant differences in ultrasonic analysis could be found between the two (group H: hyaline-like cartilage group, successful; group F: fibrous tissue group, failure). In the ultrasonic findings, the MM was 1.11+/-0.32 in group H and 0.65+/-0.18 in group F and these differences were significant (P=0.00061). Our results suggest that the ultrasonic evaluation system used in the present study is capable of judging the success or failure of cartilage regeneration procedures, and therefore, it could be a valuable tool arthroscopic diagnosis of cartilage regeneration.

Animals↗
PubMed1997

A cell-based immunobiosensor with engineered molecular recognition--Part III: Engineering molecular recognition.

We have been studying the feasibility of exploiting the recognition and amplification abilities of living immune cells for the development of hybrid immunosensors. Our group has previously reported that cell metabolic activation responses, induced by calcium ionophore A23187, can be directly transduced using calorimetric transducers, and that enzyme systems can be integrated to enhance sensing response time and output. In this study our goal was to determine the feasibility of transducing the thermal activation responses of mast cells molecularly engineered to a specific antigen. Rat peritoneal mast cells were sensitized to the model antigenic analyte dinitrophenylated-albumin (DNP-A), with monoclonal anti-DNP-A IgE, and challenged with antigen at final concentrations of 10 or 100 ng/ml. The addition of antigen resulted in the molecular triggering of cell activation, yielding thermal responses similar to those obtained previously with the ionophore model. A peak thermal response of 1.7 microW/5 x 10(5) cells was obtained within approximately 7 min of addition of antigen. The incorporation of selected amplification enzyme systems increased peak thermal outputs approximately three-fold, and reduced peak thermal response times to less than 3 min. A preliminary regression analysis of these data suggests a quantitative relationship exists between analyte concentration and peak thermal response (R = 0.988). These results support the feasibility and potential versatility of cell-based immunobiosensors for the selective detection and quantification of immunological analytes of interest.

Animals↗
PubMed1998

Cofactor engineering: a novel approach to metabolic engineering in Lactococcus lactis by controlled expression of NADH oxidase.

NADH oxidase-overproducing Lactococcus lactis strains were constructed by cloning the Streptococcus mutans nox-2 gene, which encodes the H2O-forming NADH oxidase, on the plasmid vector pNZ8020 under the control of the L. lactis nisA promoter. This engineered system allowed a nisin-controlled 150-fold overproduction of NADH oxidase at pH 7.0, resulting in decreased NADH/NAD ratios under aerobic conditions. Deliberate variations on NADH oxidase activity provoked a shift from homolactic to mixed-acid fermentation during aerobic glucose catabolism. The magnitude of this shift was directly dependent on the level of NADH oxidase overproduced. At an initial growth pH of 6.0, smaller amounts of nisin were required to optimize NADH oxidase overproduction, but maximum NADH oxidase activity was twofold lower than that found at pH 7.0. Nonetheless at the highest induction levels, levels of pyruvate flux redistribution were almost identical at both initial pH values. Pyruvate was mostly converted to acetoin or diacetyl via alpha-acetolactate synthase instead of lactate and was not converted to acetate due to flux limitation through pyruvate dehydrogenase. The activity of the overproduced NADH oxidase could be increased with exogenously added flavin adenine dinucleotide. Under these conditions, lactate production was completely absent. Lactate dehydrogenase remained active under all conditions, indicating that the observed metabolic effects were only due to removal of the reduced cofactor. These results indicate that the observed shift from homolactic to mixed-acid fermentation under aerobic conditions is mainly modulated by the level of NADH oxidation resulting in low NADH/NAD+ ratios in the cells.

Acetoin↗
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↗
PubMed2002

Engineering and cell attachment properties of human fibronectin-fibrinogen scaffolds for use in tissue engineered blood vessels.

Tissue engineered constructs reported to date have been prepared primarily from poly(glycolic) acid or collagen scaffolds onto which cells are grown and matured. In this paper we report experimental data to demonstrate the use of a natural, human protein, as a tubular scaffold for vascular grafting. Using a manual and a scalable dip-coating technique we prepared fibronectin-based tubes up to 12 cm in length and up to 3 mm in diameter. The tubes were flexible and their mechanical properties, measured in terms of tensile strength and burst pressure as a function of humidity, demonstrated their suitability as scaffolds for use in vascular grafting, e.g. coronary artery by pass grafting. In vitro tests involved the attachment of endothelial cells pumped under laminar flow conditions through the tube lumen and the adherence of smooth muscle cells on the outer surface of the tubes. These tests, carried out in multiwells, showed that the scaffolds had excellent cell attachment and guidance characteristics.

Journal Article↗
PubMed2006

Evidence-based re-engineering: re-engineering the evidence--a systematic review of the literature on business process redesign (BPR) in hospital care.

PURPOSE: Business process redesign (BPR) is used to implement organizational transformations towards more customer-focused and cost-effective care. Ideally, these innovations should be carefully described and evaluated so that "best practices" can be re-applied. To investigate this, available evidence was collected on patient care redesign projects. DESIGN/METHODOLOGY/APPROACH: The Ebsco Business Source Premier, Embase and Medline databases were searched. Studies on innovations related to re-engineering patient care that used before-after design as minimum prerequisites were selected. General characteristics, logistic parameters and other outcome measures to determine the objectives and results and interventions used were looked at. FINDINGS: A total of 86 studies that conformed to the criteria were found: a minority mentioned measurable parameters in their objectives. In the majority of studies, multiple interventions were combined within single studies, making it impossible to compare the effects of individual interventions. Only three randomized controlled trials were found. Furthermore, inconsistencies were noted between the study objectives and the reported results. Many more issues were reported in the results than were mentioned in the study aims. It would appear that publications were hard to find owing to a lack of specific MeSH headings. Nearly 7,500 abstracts were scanned and from these it was concluded that clear and univocal research methods, terms and reporting guidelines are advisable and must be developed in order to learn and benefit from BPR innovations in health care organizations. ORIGINALITY/VALUE: This appears to be the first time available evidence about redesign projects in hospitals has been systematically collected and assessed.

Evidence-Based Medicine↗
PubMed2006

[Nanogel engineering and chaperone engineering].

Chaperone-like activity (to trap proteins in biomaterials without their aggregations and to control release of proteins in a native form) is important to design protein delivery systems as well as protein engineering. In general, irreversible adsorption of proteins is unavoidable in trapping them in hydrogel biomaterials because it is difficult to control the mesh size of the hydrogel matrix. We suggested that physically cross-linked nanogels with a size comparable to that of proteins are useful for these purposes. Tailor-made functional nanogels and hydrogels were designed by self-assembly of functional associating polysaccharides such as cholesterol-bearing pullulans. The nanogels can trap hydrophobic molecules, proteins and nucleic acids. They are useful as artificial molecular chaperones and also polymeric nanocarriers in DDS.

Hydrogel, Polyethylene Glycol Dimethacrylate↗
PubMed1997

Toward a virtual-labo-system for metabolic engineering: development of biochemical engineering system analyzing tool-kit (BEST-KIT).

BEST-KIT is an efficient and user-friendly "biochemical engineering system analyzing tool-kit" integrated the following key modules: 1) mathematical modeling and editing of reaction-scheme, 2) automatic derivation of differential equations, 3) numerical calculation, 4) nonlinear optimization, 5) visualization, 6) retrieve the information on reaction mechanism and kinetic parameters from data-base of metabolic pathways. The users of this simulator are assumed to be unfamiliar with computer technology and with computer programming. The integrated interface (UNIX version) is based on Xlib, XToolkit and OSF/Motif Widget.

Biochemistry↗
PubMed1999

Antibody engineering via genetic engineering of the mouse: XenoMouse strains are a vehicle for the facile generation of therapeutic human monoclonal antibodies.

The major impediment to the development of murine monoclonal antibodies (mAbs) for therapy in humans has been the difficulty in reducing their potential immunogenicity. XenoMouse¿trade mark omitted¿ mice obviate this problem while retaining the relative ease of generating mAbs from a mouse. XenoMouse strains include germline-configured, megabase-sized YACs carrying portions of the human IgH and Igkappa loci, including the majority of the variable region repertoire, the genes for Cmicro, Cdelta and either Cgamma1, Cgamma2, or Cgamma4, as well as the cis elements required for their function. The IgH and Igkappa transgenes were bred onto a genetic background deficient in production of murine immunoglobulin. The large and complex human variable region repertoire encoded on the Ig transgenes in XenoMouse strains support the development of large peripheral B cell compartments and the generation of a diverse primary immune repertoire similar to that from adult humans. Immunization of XenoMouse mice with human antigens routinely results in a robust secondary immune response, which can ultimately be captured as a large panel of antigen-specific fully human IgGkappa mAbs of sub-nanomolar affinities. Monoclonal antibodies from XenoMouse animals have been shown to have therapeutic potential both in vitro and in vivo, and appear to have the pharmacokinetics of normal human antibodies based on human clinical trials. The utility of XenoMouse strains for the generation of large panels of high-affinity, fully human mAbs can be made available to researchers in the academic and private sectors, and should accelerate the development and application of mAbs as therapeutics for human disease.

Animals↗