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PubMed2000

[Study of human tissue engineering cartilage].

OBJECTIVE: To investigate the technique of human tissue-engineered cartilage and to study the medical collagen membrane of guided tissue regeneration (GTR) as the carrier of in vitro chondrocytes culture. METHODS: Tissue engineering technique was used to make human Tissue-engineered cartilage, which was examined histologically and functionally. RESULTS: It was found that the chondrocytes seeded on the medical collagen membrane of GTR grew well. A layer of milk white and cartilage-like tissue grew on the surface of medical collagen membrane of GTR after 1 week. It was demonstrated that the cartilage-like tissue was strong enough to be transferred after being implanted for 8 weeks. The cartilage-like tissue was proved to be human tissue engineered cartilage by HE stain and Alcian blue-poncean S stain. The chondrocytes could secrete chondroitin sulfate as proved by Lev-Spicer stain. CONCLUSIONS: The medical collagen membrane of GTR has characteristics of three-dimensional structure and cell reticular function, and it has the possibility to be developed as a natural scaffold for tissue engineering. The results indicate that it is possible to make human tissue-engineered cartilage with tissue-engineering technique.

Animals↗
PubMed2002

Injury occurrence and risk factors in construction engineers and combat artillery soldiers.

OBJECTIVES: This 1-year prospective study compared 125 construction engineers and 188 combat artillery soldiers to determine whether there were differences in injury occurrences/ types because of their diverse occupational tasks and training requirements. Also, intrinsic factors were studied to establish any associations with a soldier's risk for injury. METHODS: Prestudy height, weight, and body mass index and fitness (3.2-km run, sit-ups, push-ups) data were collected prior to the injury medical records review. Approximately 30% of each battalion was studied. RESULTS: For engineers and artillery, 86.0% and 66.0% incurred at least one injury, respectively. Of total soldiers, 64.0% of engineers and 56.4% of artillerymen had injuries associated with limited duty profiles. Total injuries resulted in 743 days of limited duty time (5.9 days per soldier) in engineers and 1,078 days (5.7 days per soldier) in artillery. Odds ratios (OR) and 95% confidence intervals (CI) were also calculated. The odds of traumatic fractures were (OR = 6.5, 95% CI = 1.8-23.7) 6 times higher in engineers than artillery, but strains/sprains and abrasions/lacerations were (OR = 2.3, 95% CI = 1.5-3.7; OR = 2.5, 95% CI = 1.2-5.0) two times higher in artillery than engineers. The number of limited duty days associated with knee injuries was significantly higher in engineers than artillery (p < 0.0001), and number of days for low back injuries was significantly higher in the artillerymen (p < 0.0001). Greater body mass was a risk factor for lower back pain and the body mass index was > or = 25 for strains/sprains in both units. CONCLUSIONS: Significant differences in injuries were reported between the two units. It is plausible that the differences were related to the diverse training exposures of the units. However, it is beyond the scope of this study to make conclusions about the causes of the injury differences. The data also indicate that body mass and body mass index were identified as modifiable injury risk factors for both units, which suggests that these injuries are preventable.

Adult↗
PubMed1997

Biological activity of particle exhaust emissions from light-duty diesel engines.

Whole diesel exhaust has been classified recently as a probable carcinogen, and several genotoxicity studies have found particulate exhaust to be clearly mutagenic. Moreover, genotoxicity of diesel particulate is greatly influenced by fuel nature and type of combustion. In order to obtain an effective environmental pollution control, combustion processes using alternative fuels are being analyzed presently. The goal of this study is to determine whether the installation of exhaust after treatment-devices on two light-duty, exhaust gas recirculation (EGR) valve-equipped diesel engines (1930 cc and 2500 cc) can reduce the mutagenicity associated with particles collected during U.S.A. and European driving cycles. Another interesting object was to compare the ability of alternative biodiesel and conventional diesel fuels to reduce the mutagenic activity associated with collected particles from two light duty diesel engines (both 1930 cc) during the European driving cycle. SOF mutagenicity was assayed using the Salmonella/microsome test (TA 98 and TA 100 strains, +/- S9 fraction). In the first part of our study, the highest mutagenicity was revealed by TA98 strain without enzymatic activation, suggesting a direct-acting mutagenicity prevalence in diesel particulate. The 2500 cc engine revealed twofold mutagenic activity compared with the 1930 cc engine (both EGR valve equipped), whereas an opposite result was found in particulate matter amount. The use of a noncatalytic ceramic trap produced a decrease of particle mutagenic activity in the 2500 cc car, whereas an enhancement in the 1930 cc engine was found. The catalytic converter and the electrostatic filter installed on the 2500 cc engine yielded a light particle amount and an SOF mutagenicity decrease. A greater engine stress was obtained using European driving cycles, which caused the strongest mutagenicity/km compared with the U.S.A. cycles. In the second part of the investigation, even though a small number of assays were available, exhaust emission generation by biodiesel fuel seemed to yield a smaller environmental impact than that of the referenced diesel fuel. The results point out the usefulness of mutagenicity testing in the research of both newer, more efficient automotive aftertreatment devices and less polluting fuels.

Air Pollutants↗
PubMedDate not supplied

Achieving the promise of clinical engineering.

Clinical engineering has failed to make the impact expected of it in the early 1970's. This failure has occurred because clinical engineering has not matured as any discipline must to achieve professional status. It does not embody a clearly understood set of capabilities. It is not based on a well-defined body of knowledge. It does not have a professional society directly representing it. This condition can be remedied by the establishment of a professional society for clinical engineering that can educate consumers about the capabilities of clinical engineers, guide providers in designing clinical engineering curricula, and promote increased involvement of clinical engineers in all high-technology areas of hospitals and in the decision-making process at their institutions.

Biomedical Engineering↗
PubMedDate not supplied

The profession of clinical engineering.

This paper reviews the sociology of professions, examines the background and historical development of professions, and then reviews the present status of the profession of clinical engineering. The historical components of the professionalization process are investigated along with the societal perceptions, the role of education, and the functions of professional societies. The progress of an occupation toward professionalization involves: the appearance of training schools; establishment of university educational programs; licensure or certification; a formal code of ethics; and establishment of one or more national professional associations. A rationale is presented here for the formation of a clearly identified professional society for clinical engineers based on: (1) The need to identify the territory of the clinical engineer by defining the body of knowledge on which clinical engineering is based; (2) The need to structure the educational system of clinical engineering; (3) The need to represent the clinical engineer in the healthcare system; and (4) The need to gain status as a profession.

Biomedical Engineering↗
PubMedDate not supplied

An open forum on: a national clinical engineering society.

An open forum was held on May 16, 1989 on the topic, A New Clinical Engineering Society? Representatives of the AAMI, IEEE/EMBS, ASHE and the SBET presented descriptions of the roles and services of their societies in support of Clinical Engineers and BMETs. Independent Clinical Engineers described their concerns regarding the development of the field; a proposal was made for the establishment of a new CE society. About 50 professionals, representing a broad cross section of clinical engineering, participated in a debate that touched on educational requirements certification, ethics, independence of action, "marketing" of the roles of CEs and BMETs, and the possible need for a new CE society. A vote was taken to represent the opinion of those present. The idea of immediately forming a new society was voted down and an ad hoc Task Force on Clinical Engineering was formed under the chairmanship of Yadin David, Ph.D. The participants called upon the AAMI, IEEE/EMBS, and the ASHE to appoint representatives to the Task Force. The new Task Force could: (1) recommend the formation of a new society; (2) call for increased cooperation between existing societies and propose long-range plans; or (3) recommend the formation of a College of Clinical Engineering or an umbrella organization to bring existing societies together.

Attitude of Health Personnel↗
PubMedDate not supplied

Education of clinical engineers in the 1990s.

This paper presents definitions of the terms bioengineering, biomedical engineering and clinical engineering. These definitions lead to the conclusion that clinical engineers must be individuals with at least a four-year bachelor's degree in an engineering specialty who are also well versed in the design, modification and testing of medical instrumentation. Educational programs for clinical engineers in the 1990s must be based upon clear definitions of these professionals' roles. Clinical engineering education should include direct professional experience obtained through internship programs similar to the program described here.

Biomedical Engineering↗
PubMedDate not supplied

Medical engineering in Switzerland.

The clinical engineering or medical engineering departments in the hospitals in Switzerland are in a phase of rapid development. In particular, staffing, as well as official recognition by hospital management, needs improvement in many of the hospitals, as is also found in other countries. An overview is given of the current state of affairs in medical engineering in Switzerland, and of the amount of annual investment in medical equipment in the public hospitals. The activities of the Swiss Association of Hospital Engineers in this field are described. The main goals, responsibilities, and tasks of medical engineering departments are presented. The importance of the integration of the medical engineering operation in the management decision process is stressed.

Biomedical Engineering↗
PubMedDate not supplied

A systems engineering approach to technology assessment.

This paper presents a technology assessment process based on systems engineering methodologies used in the aerospace and defense industries. Systems engineering, defined in the U.S. military manual for engineering management, is a logical sequence of activities and decisions transforming an operational need into a description of system performance parameters and a preferred system configuration. Like systems engineering, technology assessment is driven by a single, clear need. The objective of systems engineering is to design a new system configuration; technology assessment assesses existing technologies to address this need. A six-step technology assessment model based on systems engineering principles is presented, including: (1) needs assessment; (2) clinical feasibility analysis; (3) systems assessment; (4) approval; (5) implementation; and (6) follow-up/CQI.

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↗
PubMed2026

Engineering CRISPR for Point-of-Care Tests.

CRISPR-based molecular diagnostics have emerged as powerful and programmable platforms that enable sensitive and specific detection for disease management and epidemiological surveillance. Advances in CRISPR engineering and assay design are driving the emergence of next-generation detection platforms that are highly sensitive, rapid, and amenable to field deployment. These engineering breakthroughs have the potential to reshape point-of-care tests (POCT) and transform how emerging and persistent health threats are monitored in decentralized and resource-limited settings. Herein, we systematically review the recent advancements in CRISPR engineering strategies aimed at improving detection sensitivity and specificity, eliminating the dependence on preamplification, and enabling robust POC deployment. The discussed strategies encompass both the rational engineering of CRISPR ribonucleoproteins (RNPs) and the optimization of downstream signaling modules for molecular diagnostic applications. We further highlight key challenges and future perspectives that may inspire impactful research directions and accelerate the advancement of CRISPR engineering strategies toward robust, field-deployable POCT platforms.

CRISPR-Cas Systems↗
PubMed2000

Tissue-engineered skin (Apligraf) in the healing of patients with epidermolysis bullosa wounds.

BACKGROUND: At present, wound treatment of inherited epidermolysis bullosa (EB) is only supportive. OBJECTIVE: To determine the safety and clinical effects of tissue-engineered skin (Apligraf; Organogenesis Inc, Canton, Mass) in the healing of wounds of patients with different types of EB. DESIGN: An open-label uncontrolled study of 15 patients with EB treated with tissue-engineered skin. Each patient received tissue-engineered skin on up to 2 wounds on each of 3 clinic visits: day 1, week 6, and week 12. They were evaluated 7 (+/- 3) days and 6 weeks after each round of treatment. A quality-of-life survey was administered during week 6. SETTING: University of Miami, Miami, Fla. PATIENTS: Volunteers with EB. MAIN OUTCOME MEASURE: Safety and wound healing. RESULTS: A total of 69 different acute wounds received tissue-engineered skin at the day-1 (24 wounds), week-6 (23 wounds), and week-12 (22 wounds) visits. Overall, 63 wounds (79%) were found healed at the day-7 visit. Of the acute wounds, 82% (51/62) were healed 6 weeks after being treated, 75% (27/36) after 12 weeks, and 79% (11/14) after 18 weeks. Nine chronic wounds were also treated. Four were healed at 6 weeks; however, 7 were still open at the last clinic visit (week 18). There were no signs of rejection or clinical infection and no adverse events related to the tissue-engineered skin. The quality of life for most patients improved after treatment. Compared with patients' recollection of wounds treated with standard dressings, healing was faster and less painful. CONCLUSION: In this series of patients, tissue-engineered skin induced very rapid healing, was not clinically rejected, and was devoid of adverse effects. It was felt by the patients and families to be more effective than conventional dressings for EB wounds.

Biomedical Engineering↗
PubMedDate not supplied

Metabolic engineering: techniques for analysis of targets for genetic manipulations.

Metabolic engineering has been defined as the purposeful modification of intermediary metabolism using recombinant DNA techniques. With this definition metabolic engineering includes: (1) inserting new pathways in microorganisms with the aim of producing novel metabolites, e.g., production of polyketides by Streptomyces; (2) production of heterologous peptides, e.g., production of human insulin, erythropoitin, and tPA; and (3) improvement of both new and existing processes, e.g., production of antibiotics and industrial enzymes. Metabolic engineering is a multidisciplinary approach, which involves input from chemical engineers, molecular biologists, biochemists, physiologists, and analytical chemists. Obviously, molecular biology is central in the production of novel products, as well as in the improvement of existing processes. However, in the latter case, input from other disciplines is pivotal in order to target the genetic modifications; with the rapid developments in molecular biology, progress in the field is likely to be limited by procedures to identify the optimal genetic changes. Identification of the optimal genetic changes often requires a meticulous mapping of the cellular metabolism at different operating conditions, and the application of metabolic engineering to process optimization is, therefore, expected mainly to have an impact on the improvement of processes where yield, productivity, and titer are important design factors, i.e., in the production of metabolites and industrial enzymes. Despite the prospect of obtaining major improvement through metabolic engineering, this approach is, however, not expected to completely replace the classical approach to strain improvement-random mutagenesis followed by screening. Identification of the optimal genetic changes for improvement of a given process requires analysis of the underlying mechanisms, at best, at the molecular level. To reveal these mechanisms a number of different techniques may be applied: (1) detailed physiological studies, (2) metabolic flux analysis (MFA), (3) metabolic control analysis (MCA), (4) thermodynamic analysis of pathways, and (5) kinetic modeling. In this article, these different techniques are discussed and their applications to the analysis of different processes are illustrated.

Animals↗
PubMed1999

Morphology and mechanical function of long-term in vitro engineered cartilage.

Cartilage tissue can be engineered in vitro with articular chondrocytes and poly(glycolic acid) nonwoven scaffolds as previously shown over 12 weeks in vitro. This study addressed whether engineered cartilage would further evolve and approach natural cartilage in extracellular matrix organization and biomechanical properties, especially aggregate modulus through longer term in vitro cultivation. Cellularity, cell size, compressive modulus, and permeability of the in vitro engineered cartilage stabilized within the 12-week cultivation time and remained at the same levels as those of natural cartilage thereafter. The linear range of the stress-strain curve was from 0 to a strain value between 5 and 10% for all the engineered cartilage tissues that were in vitro cultured for longer than 2 weeks, which was the same linear range for natural cartilage. The aggregate modulus further increased from week 12 to week 20 and remained approximately the same value thereafter during a 25-week in vitro cultivation. The aggregate modulus of the engineered cartilage reached 179+/-9 kPa after 20 weeks of in vitro cultivation, which was 40% that of natural articular cartilage. To our knowledge this is the highest aggregate modulus value yet reported of any in vitro engineered cartilage tissue.

Animals↗
PubMed2002

Effects of oxygen on engineered cardiac muscle.

Concentration gradients associated with the in vitro cultivation of engineered tissues that are vascularized in vivo result in the formation of only a thin peripheral tissue-like region (e.g., approximately 100 microm for engineered cardiac muscle) around a relatively cell-free interior. We previously demonstrated that diffusional gradients within engineered cardiac constructs can be minimized by direct perfusion of culture medium through the construct. In the present study, we measured the effects of medium perfusion rate and local oxygen concentration (p(O2)) on the in vitro reconstruction of engineered cardiac muscle. Neonatal rat cardiomyocytes were seeded onto biodegradable polymer scaffolds (fibrous discs, 1.1 cm diameter x 2 mm thick, made of polyglycolic acid, 24 x 10(6) cells per scaffold). The resulting cell-polymer constructs were cultured for a total of 12 days in serially connected cartridges (n = 1-8), each containing one construct directly perfused with culture medium at a flow rate of 0.2-3.0 mL/min. In all groups, oxygen concentration decreased due to cell respiration, and depended on construct position in the series and medium flow rate. Higher perfusion rates and higher p(O2) correlated with more aerobic cell metabolism, and higher DNA and protein contents. Constructs cultured at p(O2) of 160 mm Hg had 50% higher DNA and protein contents, markedly higher expression of sarcomeric alpha-actin, better organized sarcomeres and cell junctions, and 4.5-fold higher rate of cell respiration as compared to constructs cultured at p(O2) of 60 mm Hg. Contraction rates of the corresponding cardiac cell monolayers were 40% higher at p(O2) of 160 than 60 mm Hg. The control of oxygen concentration in cell microenvironment can thus improve the structure and function of engineered cardiac muscle. Experiments of this kind can form a basis for controlled studies of the effects of oxygen on the in vitro development of engineered tissues.

Animals↗
PubMed2002

In vivo evaluation of a bioactive scaffold for bone tissue engineering.

Revision cases of total hip implants are complicated by the significant amount of bone loss. New materials and/or approaches are needed to provide stability to the site, stimulate bone formation, and ultimately lead to fully functional bone tissue. Porous bioactive glasses (prepared from 45S5 granules, 45% SiO2, 24.5% Na2O, 24.5% CaO, and 6% P2O5) have been developed as scaffolds for bone tissue engineering and have been studied in vitro. In this study, we investigated the incorporation of tissue-engineered constructs utilizing these scaffolds in large, cortical bone defects in the rat simulating revision conditions. With implantation times of 2, 4, and 12 weeks the results were compared to those using the bioactive ceramic scaffold alone. Two tissue-engineered constructs were studied: osteoprogenitor cells that were either seeded onto the scaffold prior to implantation ("primary") or those that were culture expanded to form bonelike tissue on the scaffold prior to implantation ("hybrid"). Defects treated with the hybrid had the greatest amount of bone in the available pore space of the defect over all other groups at 2 weeks (p < 0.05). For both the primary and hybrid groups, woven and lamellar bone was present along the interface of the scaffold and the host cortex and within the porous space of the scaffold at 2 weeks. By 4 weeks, very uniform, lamellar bone was present throughout the scaffold for both tissue-engineered groups. The amount of bone significantly increased over time for all groups while the bioactive ceramic gradually resorbed by 40% at 12 weeks (p < 0.05). Structural properties of the treated long bones improved over time. Long bones treated with the hybrid had an early return in torsional stiffness by 2 weeks. Both tissue-engineered constructs achieved normal torsional strength and stiffness by 4 weeks as compared to the scaffold alone, which achieved this by 12 weeks. Porous, surface modified bioactive ceramic is a promising scaffold material for tissue-engineered bone repair.

Animals↗
PubMed2001

Flux estimation using isotopic tracers: common ground for metabolic physiology and metabolic engineering.

Metabolic physiologists and metabolic engineers share the need to estimate flux. However, the physiologist often works with systems that do not maintain steady state for long. Many sites cannot be sampled, and calculating mass and isotopic balance for the entire system may not be feasible. To deal with these constraints, metabolic physiologists have developed specialized isotopic techniques that may be unfamiliar to metabolic engineers. A selection of these techniques is presented here, not because it is anticipated that they would be used by engineers exactly as in the physiologist's setting, but because they illustrate novel applications of tracer methodology. Creative engineers may find new adaptations of these tools in metabolic engineering and opportunities to increase redundancy. Physiologists, entering into a dialog with engineers, may see more clearly the potential of comprehensive models and revisit the impediments to a more complete analysis of human metabolic systems.

Animals↗
PubMed1986

Legal and regulatory aspects of genetically engineered animals.

The commercialization of genetically engineered food animals will pose a number of legal and regulatory questions. These may be grouped into questions of process and questions of products. The process of animal genetic engineering with artificially constructed vectors will probably be regulated in much the same manner as other veterinary procedures. There may be some discussion, however, as to whether animal drug or animal biologic regulations are more applicable. The products of animal genetic engineering, i.e., transgenic food animals and food products made from them, also raise important questions about product safety and identity. These include whether and how genetically engineered food animals will be subject to federal inspection for wholesomeness, whether artificial vectors, foreign genes, or gene products will adulterate recipient animal tissues, and how food products made from such animals will be labeled. Prior federal experience with the inspection of interspecific hybrids of cattle and buffalo provides a useful basis for further policy developments in the inspection and labeling of genetically engineered food animals. In particular, the inspection of cattle/buffalo hybrids has established a phenotypic (based on appearance) criterion for deciding how novel food animals should be inspected. As the genetic engineering of food animals on a production basis draws nearer, it may be necessary to supplement the phenotypic criterion with genetic (based on pedigree) criteria to assure that the essential characteristics of animals slaughtered under current food statutes are maintained.

Animal Husbandry↗