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PubMed2001

A new system for understanding modes of mechanical ventilation.

Numerous ventilation modes and ventilation options have become available as new mechanical ventilators have reached the market. Ventilator manufacturers have no standardized terminology for ventilator modes and ventilation options, and ventilator operator's manuals do not help the clinician compare the modes of ventilators from different manufacturers. This article proposes a standardized system for classifying ventilation modes, based on general engineering principles and a small set of explicit definitions. Though there may be resistance by ventilator manufacturers to a standardized system of ventilation terminology, clinicians and health care equipment purchasers should adopt such a system in the interest of clear communication--the lack of which prevents clinicians from fully understanding the therapies they administer and could compromise the quality of patient care.

Biomedical Engineering↗
PubMed2000

Matrix-mixed culture: new methodology for chondrocyte culture and preparation of cartilage transplants.

For cartilage engineering a variety of biomaterials were applied for 3-dimensional chondrocyte embedding and transplantation. In order to find a suitable carrier for the in vitro culture of chondrocytes and the subsequent preparation of cartilage transplants we investigated the feasibility of a combination of the well-established matrices fibrin and alginate. In this work human articular chondrocytes were embedded and cultured either in alginate, a mixture of alginate and fibrin, or in a fibrin gel after the extraction of the alginate component (porous fibrin gel) over a period of 30 days. Histomorphological analysis, electron microscopy, and immunohistochemistry were performed to evaluate the phenotypic changes of the chondrocytes, as well as the quality of the newly formed cartilaginous matrix. Our experiments showed that a mixture of 0.6% alginate with 4.5% fibrin promoted sufficient chondrocyte proliferation and differentiation, resulting in the formation of a specific cartilage matrix. Alginate served as a temporary supportive matrix component during in vitro culture and can be easily removed prior to transplantation. The presented tissue engineering method on the basis of a mixed alginate-fibrin carrier offers the opportunity to create stable cartilage transplants for reconstructive surgery.

Alginates↗
PubMed2002

Short monolithic columns as stationary phases for biochromatography.

Monolithic supports represent a novel type of stationary phases for liquid and gas chromatography, for capillary electrochromatography, and as supports for bioconversion and solid phase synthesis. As opposed to individual particles packed into chromatographic columns, monolithic supports are cast as continuous homogeneous phases. They represent an approach that provides high rates of mass transfer at lower pressure drops as well as high efficiencies even at elevated flow rates. Therefore, much faster separations are possible and the productivity of chromatographic processes can be increased by at least one order of magnitude as compared to traditional chromatographic columns packed with porous particles. Besides the speed, the nature of the pores allows easy access even in the case of large molecules, which make monolithic supports a method of choice for the separation of nanoparticles like pDNA and viruses. Finally, for the optimal purification of larger biomolecules, the chromatographic column needs to be short. This enhances the speed of the separation process and reduces backpressure, unspecific binding, product degradation and minor changes in the structure of the biomolecule, without sacrificing resolution. Short Monolithic Columns (SMC) were engineered to combine both features and have the potential of becoming the method of choice for the purification of larger biomolecules and nanopartides on the semi-preparative scale.

Biomedical Engineering↗
PubMed1995

Tissue-engineered cartilage for implantation and grafting.

Facial plastic and reconstructive surgeons are continually faced with the dilemma of what material to use for implantation and grafting. Tissue-engineered cartilage is a relatively new and exciting concept which utilizes chondrocytes and cultures them on a three-dimensional biodegradable template. This template/cell complex is first briefly incubated in vitro, then implanted into a recipient host. In situ the template resorbs and is replaced with new cartilage that is viable, compatible, and mature. This paper discusses the biochemical composition of cartilage, the concept of tissue engineering, advances in template quality, and cartilage immunogenicity. Future clinical applications of this type of graft research include microtia repair, facial reconstruction, rhinoplasty, and other facial cosmetic procedures.

Animals↗
PubMedDate not supplied

Review: application of stem cells for vascular tissue engineering.

As the prevalence of vascular disease has continued to expand, the need for a suitable arterial replacement has prompted researchers to look beyond synthetic and autologous grafts toward the field of tissue engineering. Advances in vascular tissue engineering have utilized both mesenchymal and hematopoietic stem cells as a cell source in an attempt to create a fully engineered small-diameter graft. Stem cells offer enormous potential as a cell source because of their proliferative and growth potential, and the application of stem cell technology has far-reaching implications for future applications. The innovative use of stem cells for vascular tissue engineering has opened new possibilities for a fully engineered blood vessel. The purpose of this review is to summarize the current perspective on the use of stem cells for vascular tissue engineering. It focuses principally on the classes of stem cells used, techniques for differentiation scaffolding technology, and the successes and failures of models.

Animals↗
PubMedDate not supplied

Clinical engineering's role in managing clinical alarm risk.

This manuscript highlights the role that clinical engineering can play to minimize the risk of problems associated with clinical alarms. AAMI held a town meeting on clinical alarm management and integration during its 2005 Annual Conference & Expo. The meeting highlighted some excellent suggestions on how the whole concept of improving clinical alarm design and implementation must be addressed in a systematic way. Examples of how the clinical engineering profession can contribute to this effort include participation in more AAMI town hall meetings and other conferences, providing design suggestions to medical device manufacturers, and participation in the development of alarm-related standards.

Biomedical Engineering↗
PubMedDate not supplied

Tissue engineering of autologous cartilage transplants for rhinology.

In reconstructive surgery there is increasing demand for cartilage transplants to fill defects, especially nose and/or outer ear defects. Tissue engineering is one of the most modern pathways to generate autologous cartilage transplants. Isolated chondrocytes obtained from a tiny patient's biopsy were seeded on bioresorbable preshaped cell carriers to provide a 3-dimensional cell arrangement as in vivo. The combined use of these cell carriers in form of a non-woven mesh and a constant medium perfusion was performed to generate a cartilage-like cell-polymer-construct, which was finally subcutanously implanted in nude mice for full maturation. After explantation of 6 months, expression of cartilage specific extracellular matrix molecules was obvious by using histochemical and immunohistochemical methods. These data show that tissue engineering with isolated multiplied human chondrocytes from a tiny biopsy seeded on bioresorbable polymer is a promising system to generate autologous cartilage transplants for replacements in reconstructive surgery.

Animals↗
PubMed1994

Electromagnetic interference: causes and concerns in the health care environment.

In the past 15 years there has been a dramatic increase in the number of radio frequency emission sources that have entered medical treatment areas. Personal computers, digital pagers, hand-held radios, cellular phones, and wireless input devices have all become more prevalent in the contemporary clinical environment. Because of the productivity gains these devices promise, it is unlikely that the use of electronic instrumentation and wireless technologies will diminish--in fact greater uses are projected. Along with the benefits these devices provide, they also create a greater opportunity for increased electromagnetic interference among devices. It is important that engineering and professional staff are aware of some of the complex interactions these devices can create. Managing this emerging problem should be a concern for the medical community. Engineering staff should be able to communicate effectively with medical staff, patients, and visitors regarding potential interactions and how to recognize them and mitigate their consequences.

Academies and Institutes↗
PubMedDate not supplied

[Development of instrumental technologies of assessment of higher mental functions in health and disease].

The current increase in the incidence of nervous and mental diseases makes it necessary to use monitoring means for dysfunctions of the central nervous system. The paper analyzes promising ways of development of medical engineering technologies for studies, diagnosis, and rehabilitation in higher mental dysfunctions. Particular emphasis is laid on the instrumental methods for examining the higher nervous performance and relevant technical means.

Adolescent↗
PubMed1988

Effective use of physics services in the NHS.

The work of medical physics departments in the national health service encompasses physics, electronic and mechanical engineering, computing, mathematics, biophysics and bioengineering. In some cases, there are separate bioengineering departments, but for the purpose of this article, no distinction is made.

Biomedical Engineering↗
PubMedDate not supplied

Development phases for medical devices.

An orderly procedure for analyzing potential new medical devices to determine whether or not they should be commercially developed is presented. A product checklist screens devices to determine their need and whether they will be economically viable. A design specification ensures that design engineers, marketing personnel, and financial personnel agree on function and costs. Reviews during the design, development, pre-production, and production provide continual management of the project to keep it on course.

Biomedical Engineering↗
PubMedDate not supplied

The orthopedic surgeon and rehabilitation engineering.

Rapid advancements in technology in the past 30 years have brought about a close relationship between medicine and engineering. Part of this has been the close association of orthopedics and the prosthetics and orthotics technologies. In recent years, advances in other aspects of rehabilitation engineering have taken place; these have been partly based on the technology established by research in prosthetics and orthotics. The rapid progress in rehabilitation engineering now demands the attention of orthopedists. The role of the rehabilitation engineer is defined, and some examples are given of the kinds of problems confronted by the rehabilitation engineering clinic team. Especially as further progress takes place, the orthopedic surgeon and the prosthetist-orthotist need to obtain more knowledge of the technical aids needed to restore independence to the disabled.

Biomedical Engineering↗
PubMed2002

[Novel scaffold materials for tissue engineering].

In this paper, the resorbable and degradable biomaterials often used in recent years are reviewed. These materials include natural and synthetical ones such as collagen, protein fiber, chitosan, polylactic acid (PLA), polyglycolic acid(PGA), polyanlydrides, etc.

Biocompatible Materials↗
PubMed1998

Creation of viable pulmonary artery autografts through tissue engineering.

BACKGROUND: "Repair" of many congenital cardiac defects requires the use of conduits to establish right ventricle to pulmonary artery continuity. At present, available homografts or prosthetic conduits lack growth potential and can become obstructed by tissue ingrowth or calcification leading to the need for multiple conduit replacements. Tissue engineering is an approach by which cells are grown in vitro onto biodegradable polymers to construct "tissues" for implantation. A tissue engineering approach has recently been used to construct living cardiac valve leaflets from autologous cells in our laboratory. This study assesses the feasibility of a tissue engineering approach to constructing tissue-engineered "living" pulmonary artery conduits. MATERIALS AND METHODS: Ovine artery (group A, n = 4) or vein (group V, n = 3) segments were harvested, separated into individual cells, expanded in tissue culture, and seeded onto synthetic biodegradable (polyglactin/polyglycolic acid) tubular scaffolds (20 mm long x 15 mm diameter). After 7 days of in vitro culture, the autologous cell/polymer vascular constructs were used to replace a 2 cm segment of pulmonary artery in lambs (age 68.4 +/- 15.5 days, weight 18.7 +/- 2.0 kg). One other control animal received an acellular polymer tube sealed with fibrin glue without autologous cells. Animals were sacrificed at intervals of 11 to 24 weeks (mean follow-up 130.3 +/- 30.8 days, mean weight 38.9 +/- 13.0 kg) after echocardiographic and angiographic studies. Explanted tissue-engineered conduits were assayed for collagen (4-hydroxyproline) and calcium content, and a tissue deoxyribonucleic acid assay (bis-benzimide dye) was used to estimate number of cell nuclei as an index of tissue maturity. RESULTS: The acellular control graft developed progressive obstruction and thrombosis. All seven tissue-engineered grafts were patent and demonstrated a nonaneurysmal increase in diameter (group A = 18.3 +/- 1.3 mm = 95.3% of native pulmonary artery; group V = 17.1 +/- 1.2 mm = 86.8% of native pulmonary artery). Histologically, none of the biodegradable polymer scaffold remained in any tissue-engineered graft by 11 weeks. Collagen content in tissue-engineered grafts was 73.9% +/- 8.0% of adjacent native pulmonary artery. Histologically, elastic fibers were present in the media layer of tissue-engineered vessel wall and endothelial specific factor VIII was identified on the luminal surface. Deoxyribonucleic acid assay showed a progressive decrease in numbers of cell nuclei over 11 and 24 weeks, suggesting an ongoing tissue remodeling. Calcium content of tissue-engineered grafts was elevated (group A = 7.95 +/- 5.09; group V = 13.2 +/- 5.48; native pulmonary artery = 1.2 +/- 0.8 mg/gm dry weight), but no macroscopic calcification was found. CONCLUSIONS: Living vascular grafts engineered from autologous cells and biodegradable polymers functioned well in the pulmonary circulation as a pulmonary artery replacement. They demonstrated an increase in diameter suggesting growth and development of endothelial lining and extracellular matrix, including collagen and elastic fibers. This tissue-engineering approach may ultimately allow the development of viable autologous vascular grafts for clinical use.

Animals↗
PubMed2000

The living shunt: a tissue engineering approach in the treatment of hydrocephalus.

Tissue engineering is the use of cultured cells seeded into biodegradable polymers to create custom designed, living implantable devices. As a first approach to the use of this technique in the treatment of hydrocephalus, we have prepared chondrocyte-seeded polyglycolic acid (PGA) tubes coated with polylactic glycolic acid (PGLA), implanted initially with thin silastic stents removed four weeks after shunt insertion. The use of bovine xenograft cells in athymic (nude) rats resulted in more efficient seeding with chondrocytes, stiffer tube walls, and better patency. When implanted in 6-week-old rats made hydrocephalic by cisternal injection of kaolin at 4 weeks of age, six of eight 'living shunts' remained patent to radio-opaque contrast injection at two weeks after stent removal. At four weeks after stent removal, all four of the shunts had occluded at the ventricular end, three of the four apparently due to growth of the animal. We conclude that polymer type, cell type, and cell density will require considerable optimization, but a working tissue engineered shunt is feasible and may one day address some problems of interactions of living tissue and inert polymer.

Animals↗
PubMed1993

Tissue engineering.

The loss or failure of an organ or tissue is one of the most frequent, devastating, and costly problems in human health care. A new field, tissue engineering, applies the principles of biology and engineering to the development of functional substitutes for damaged tissue. This article discusses the foundations and challenges of this interdisciplinary field and its attempts to provide solutions to tissue creation and repair.

Animals↗
PubMed2005

Professor Joseph Warren Horton (1889-1967): biological engineer.

Joseph Warren Horton graduated with a degree in electrical engineering from the Massachusetts Institute of Technology (MIT) in 1914. He became involved in the early development of electrical measurement devices, televised image transmission, and the detection of underwater sound transmission. In the mid-1930s he was appointed the first leader of the newly created Department of Biological Engineering at MIT and in this position he made major contributions to the application of physics to human physiology, in particular by increasing the safety of explosive inhalational anaesthetic agents.

Academies and Institutes↗
PubMed2003

On the modelling bone tissue fracture and healing of the bone tissue.

This paper reviews the available literature on computational modelling in two areas of bone biomechanics: fracture and healing. Bone fracture analysis attempts to predict the failure of musculoskeletal structures by several possible mechanisms under different loading conditions. However, as opposed to structurally inert materials, bone is a living tissue that can repair itself. An exciting new field of research is being developed to better comprehended these mechanisms and the mechanical behaviour of bone tissue. One of the main goals of this work is to demonstrate, after a review of computational models, the main similarities and differences between normal engineering materials and bone tissue from a structural point of view. We also underline the importance of computational simulations in biomechanics due to the difficulty of obtaining experimental or clinical results.

Biomechanical Phenomena↗