Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Engineering”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed2006

Is a collagen scaffold for a tissue engineered nucleus replacement capable of restoring disc height and stability in an animal model?

The idea of a tissue engineered nucleus implant is to seed cells in a three-dimensional collagen matrix. This matrix may serve as a scaffold for a tissue engineered nucleus implant. The aim of this study was to investigate whether implantation of the collagen matrix into a spinal segment after nucleotomy is able to restore disc height and flexibility. The implant basically consists of condensed collagen type-I matrix. For clinical use, this matrix will be used for reinforcing and supporting the culturing of nucleus cells. In experiments, matrixes were concentrated with barium sulfate for X-ray purposes and cell seeding was disclaimed in order to evaluate the biomechanical performance of the collagen material. Six bovine lumbar functional spinal units, aging between 5 and 6 months, were used for the biomechanical in-vitro test. In each specimen, an oblique incision was performed, the nucleus was removed and replaced by a collagen-type-I matrix. Specimens were mounted in a custom-built spine tester, and subsequently exposed to pure moments of 7.5 Nm to move within the three anatomical planes. Each tested stage (intact, nucleotomy and implanted) was evaluated for range of motion, neutral zone and change in disc height. Removal of the nucleus significantly reduced disc height by 0.84 mm in respect to the intact stage and caused an instability in the segment. Through the implantation of the tissue engineered nucleus it was possible to restore this height and stability loss, and even to increase slightly the disc height of 0.07 mm compared with the intact stage. There was no statistical difference between the stability provided by the implant and intact stage. Results of movements in lateral bending and axial rotation showed the same trend compared to flexion/extension. However, implant extrusions have been observed in three of six cases during the flexibility assessment. The results of this study directly reflect the efficacy of vital nucleus replacement to restore disc height and to provide stability to intervertebral discs. However, from a biomechanical point of view, the challenge is to employ an appropriate annulus fibrosus sealing method, which is capable to keep the nucleus implant in place over a long-time period. Securing the nucleus implant inside the disc is one of the most important biomechanical prerequisites if such a tissue engineered implant shall have a chance for clinical application.

Absorbable Implants↗
PubMed2002

[Clinical application of tissue-engineered autologous oral mucosa transplants].

BACKGROUND: Tissue engineering of autogenous oral mucosa is a significant enrichment for various indications in oral and maxillofacial surgery. Besides preprosthetic surgery and prelamination of microvascular fasciocutaneous flaps, interdisciplinary work such as reconstruction procedures in cases of hypospadias and epispadias are the main indications for tissue-engineered oral mucosa. RESULTS: One main advantage of this technique is the reduction of second surgical procedures. The morbidity is decreased and the quality of life may be significantly increased. The manufacture of tissue-engineered autogenous oral mucosa up to 15 cm(2) requires a small biopsy of oral mucosa (4-8 mm(3)) and 40 ml of autogenous serum. DISCUSSION: The clinical and morphological long-term follow-up after different surgical procedures with tissue-engineered oral mucosa establishes this technique as an excellent additional tool in oral and maxillofacial surgery.

Female↗
PubMed2004

Diffusion in musculoskeletal tissue engineering scaffolds: design issues related to porosity, permeability, architecture, and nutrient mixing.

The field of tissue engineering continues to advance with the discovery of new biomaterials, growth factors and scaffold fabrication techniques. However, for the ultimate success of a tissue engineered construct the issue of nutrient transport to the scaffold interior needs to be addressed. Often, the requirements for adequate nutrient supply are at odds with other scaffold design parameters such as mechanical properties as well as scaffold fabrication techniques, leading to incongruities in finding optimal solutions. The goal of this review article is to provide an overview of the various engineering design factors that promote movement of nutrients, waste and other biomolecules in scaffolds for musculoskeletal tissue engineering applications. The importance of diffusion in scaffolds and how it is influenced by porosity, permeability, architecture, and nutrient mixing has been emphasized. Methods for measuring porosity and permeability have also been outlined. The different types of biomaterials used, scaffold fabrication techniques implemented and the pore sizes/porosities obtained over the past 5 years have also been addressed.

Animals↗
PubMed2005

Effects of initial cell seeding density for the tissue engineering of the temporomandibular joint disc.

Tissue engineering may provide a better treatment modality for postoperative discectomy patients. The TMJ disc is an ideal candidate for tissue engineering approaches because of its lack of an intrinsic regenerative ability. Unfortunately, basic knowledge related to TMJ disc tissue engineering is still at an infancy level and not on par to that related to articular cartilage tissue engineering. The objective of this study was to examine the effects of initial cell density of TMJ disc cells seeded in nonwoven poly-glycolic acid (PGA) scaffolds on the biochemical and biomechanical properties of constructs examined at 0, 3, and 6 weeks after seeding. Low, medium, and high seeding densities were chosen to be 15, 30, and 120 million cells per ml of scaffold, which were seeded using a spinner flask. Significant differences were found temporally and as a function of seeding density in morphology, total collagen, GAG content, and permeability of the constructs, but not in aggregate modulus. The high seeding density group outperformed the low and medium groups in collagen and GAG content at all time points measured. The high-density group produced a total of 55.37 +/- 3.56 microg of collagen per construct, maintained 15.77 +/- 1.86 microg of GAG per construct, and only shrunk to 50% of the original scaffold size. Permeability of the constructs at 6 weeks was decreased by 70% compared to 0 weeks.

Animals↗
PubMed2005

Computer-aided tissue engineering of a human vertebral body.

Tissue engineering is developing into a less speculative science involving the careful interplay of numerous design parameters and multidisciplinary professionals. Problem solving abilities and state of the art research tools are required to develop solutions for a wide variety of clinical issues. One area of particular interest is orthopedic biomechanics, a field that is responsible for the treatment of over 700,000 vertebral fractures in the United States alone last year. Engineers are currently lacking the technology and knowledge required to govern the subsistence of cells in vivo, let alone the knowledge to create a functional tissue replacement for a whole organ. Despite this, advances in computer-aided tissue engineering are continually growing. Using a combinatory approach to scaffold design, patient-specific implants may be constructed. Computer-aided design, optimization of geometry using voxel finite element models or other optimization routines, creation of a library of architectures with specific material properties, rapid prototyping, and determination of a defect site using imaging modalities highlight the current availability of design resources. This study proposes a novel methodology from start to finish which could, in the future, be used to design a tissue-engineered construct for the replacement of an entire vertebral body.

Biocompatible Materials↗
PubMed2005

Tissue engineering of human heart valve leaflets: a novel bioreactor for a strain-based conditioning approach.

Current mechanical conditioning approaches for heart valve tissue engineering concentrate on mimicking the opening and closing behavior of the leaflets, either or not in combination with tissue straining. This study describes a novel approach by mimicking only the diastolic phase of the cardiac cycle, resulting in tissue straining. A novel, yet simplified, bioreactor system was developed for this purpose by applying a dynamic pressure difference over a closed tissue engineered valve, thereby inducing dynamic strains within the leaflets. Besides the use of dynamic strains, the developing leaflet tissues were exposed to pre-strain induced by the use of a stented geometry. To demonstrate the feasibility of this strain-based conditioning approach, human heart valve leaflets were engineered and their mechanical behavior evaluated. The actual dynamic strain magnitude in the leaflets over time was estimated using numerical analyses. Preliminary results showed superior tissue formation and non-linear tissue-like mechanical properties in the strained valves when compared to non-loaded tissue strips. In conclusion, the strain-based conditioning approach, using both pre-strain and dynamic strains, offers new possibilities for bioreactor design and optimization of tissue properties towards a tissue-engineered aortic human heart valve replacement.

Aortic Valve↗
PubMed2005

Chitosan particles agglomerated scaffolds for cartilage and osteochondral tissue engineering approaches with adipose tissue derived stem cells.

It is well accepted that natural tissue regeneration is unlikely to occur if the cells are not supplied with an extracellular matrix (ECM) substitute. With this goal, several different methodologies have been used to produce a variety of 3D scaffolds as artificial ECM substitutes suitable for bone and cartilage tissue engineering. Furthermore, osteochondral tissue engineering presents new challenges since the combination of scaffolding and co-culture requirements from both bone and cartilage applications is required in order to achieve a successful osteochondral construct. In this paper, an innovative processing route based on a chitosan particles aggregation methodology for the production of cartilage and osteochondral tissue engineering scaffolds is reported. An extensive characterization is presented including a morphological evaluation using Micro-Computed Tomography (microCT) and 3D virtual models built with an image processing software. Mechanical and water uptake characterizations were also carried out, evidencing the potential of the developed scaffolds for the proposed applications. Cytotoxicity tests show that the developed chitosan particles agglomerated scaffolds do not exert toxic effects on cells. Furthermore, osteochondral bilayered scaffolds could also be developed. Preliminary seeding of mesenchymal stem cells isolated from human adipose tissue was performed aiming at developing solutions for chondrogenic and osteogenic differentiation for osteochondral tissue engineering applications.

Adipose Tissue↗
PubMed2006

Ethical concepts regarding the genetic engineering of laboratory animals: A confrontation with moral beliefs from the practice of biomedical research.

Intrinsic value and animal integrity are two key concepts in the debate on the ethics of the genetic engineering of laboratory animals. These concepts have, on the one hand, a theoretical origin and are, on the other hand, based on the moral beliefs of people not directly involved in the genetic modification of animals. This 'external' origin raises the question whether these concepts need to be adjusted or extended when confronted with the moral experiences and opinions of people directly involved in the creation or use of transgenic laboratory animals. To answer this question, 35 persons from the practice of biomedical research who are directly involved in genetic engineering (scientists, biotechnicians, animal caretakers and laboratory animal scientists) were interviewed. They were asked to give their moral opinion on different aspects of the genetic engineering of animals and to react to statements about the concepts of intrinsic value and animal integrity. Analysis of the interviews showed that, contrary to what is often assumed, the respondents embraced these concepts, even those senses that (more) specifically apply to genetic engineering. And although the respondents raised some objections that go beyond issues of animal welfare, these objections could quite well be expressed in terms of the concepts of intrinsic value and animal integrity. In short, the results of the present study strongly suggest that these concepts do not have to be adjusted or extended in the light of the moral experiences and opinions from practice.

Animals↗
PubMed2000

An approach to integrating "professional responsibility" in engineering into the capstone design experience.

ABET 2000 Criteria encourages development of proficiency in professional responsibility in engineering as part of the undergraduate curriculum. This paper discusses the use of industrially sponsored capstone design projects to encourage active discussion of professional responsibility in engineering that naturally occurs during the engineering design process. The paper also discusses student participation in designing responses and approaches to issues such as engineering ethics. The paper includes specific examples of topics addressed by students and the approaches developed (by students) in addressing these issues.

Curriculum↗
PubMed2000

Examples of real world engineering ethics problems.

Nine examples are presented illustrating the kinds of problems encountered in actual practice by conscientious engineers. These cases are drawn fom the records of the IEEE Ethics Committee, and from the experience of the ethics helpline initiated recently by the Online Ethics Center for Engineering and Science. They range from situations in which companies try to cheat one another to those in which human health and safety are jeopardized. In one case, an engineer learned that even a quiet resignation can prove very costly in a personal sense. Some ways in which professional societies might make ethical practice of engineering somewhat easier are mentioned.

Academies and Institutes↗
PubMed2001

The greening of engineers: a cross-cultural experience.

Experience with a group of mechanical engineering seniors at the University of Colorado led to an informal experiment with engineering students in India. An attempt was made to qualitatively gauge the students' ability to appreciate a worldview different from the standard engineering worldview--that of a mechanical universe. Qualitative differences between organic and mechanical systems were used as a point of discussion. Both groups were found to exhibit distinct thought and behavior patterns which provide important clues for sensitizing engineers to environmental issues in future educational initiatives. Cross-cultural and global dimensions of these initiatives are discussed.

Colorado↗
PubMed2001

Software Engineering Code of Ethics and Professional Practice.

The Software Engineering Code of Ethics and Professional Practice, intended as a standard for teaching and practicing software engineering, documents the ethical and professional obligations of software engineers. The code should instruct practitioners about the standards society expects them to meet, about what their peers strive for, and about what to expect of one another. In addition, the code should also inform the public about the responsibilities that are important to the profession. Adopted in 2000 by the IEEE Computer Society and the ACM--two leading international computing societies--the code of ethics is intended as a guide for members of the evolving software engineering profession. The code was developed by a multinational task force with additional input from other professionals from industry, government posts, military installations, and educational professions.

Ethics, Professional↗
PubMed2002

Representation and misrepresentation: Tufte and the Morton Thiokol engineers on the Challenger.

This paper examines the role of the Morton Thiokol engineers in the decisions surrounding the launch of the Challenger, particularly with reference to an analysis of this event by Edward Tufte. The engineers at Morton Thiokol recommended against the launch of Challenger because the projected launch temperature between 26 degrees F to 29 degrees F was far outside their field database of successful launches. The engineers had asked for, but not received, data necessary to determine the cause of massive blow-by on the launch the previous January, and they had informed their managers and NASA that continuing flights could be catastrophic if the cause of the problems with the launches was not discovered. The authors conclude that the engineers thus did what they were ethically as well as professionally obligated to do.

Accidents, Aviation↗
PubMed2003

Towards emergent ethical action and the culture of engineering.

With the advent of the newest technologies, it is necessary for engineering to incorporate the integration of social responsibility and technical integrity. A possible approach to accomplishing this integration is by expanding the culture of the engineering profession so that it is more congruent with the complex nature of the technologies that are now being developed. Furthermore, in order to achieve this expansion, a shift in thinking is required from a linear or reductionist paradigm (atomistic, deterministic and dualistic) to a nonlinear paradigm (holistic, chaotic and subjective). Three aspects of such a nonlinear paradigm (holism, transparency and responsiveness) enable an engineer to shift from "applying ethics" to "being ethical". This culture change can be a basis for developing new curricula to satisfy the ABET-2000 requirements as well as for the practice of engineering in the 21st Century.

Engineering↗
PubMed2003

An effective strategy for integrating ethics across the curriculum in engineering: an ABET 2000 challenge.

This paper describes a one-day workshop format for introducing ethics into the engineering curriculum prepared at the University of Puerto Rico at Mayagüez (UPRM). It responds to the ethics criteria newly integrated into the accreditation process by the Accreditation Board of Engineering and Technology (ABET). It also employs an ethics across the curriculum (EAC) approach; engineers identify the ethical issues, write cases that dramatize these issues, and then develop exercises making use of these cases that are specially tailored to mainstream engineering classes. The different activities and strategies employed in this workshop are set forth. Specific references are made to the cases and exercises developed as a result of these workshops. The paper ends by summarizing the different assessments made of the workshop by addressing the following questions: how did it contribute to the overall ABET effort at UPRM; could other universities benefit from a similar activity; and how did the participants evaluate the workshop?

Accreditation↗
PubMed2004

Teaching business ethics to professional engineers.

Without question "business ethics" is one of the hot topics of the day. Over the past months we have seen business after business charged with improper practices that violate commonly-accepted ethical norms. This has led to a loss of confidence in corporate management, and has had severe economic consequences. From many quarters business educators have heard the call to put more emphasis on ethical practices in their business courses and curricula. Engineering educators are also heeding this call, since the practice of engineering usually involves working for (or leading) a business and/or engaging in business transactions. In the summer of 2002, Auburn University's Engineering Professional Development program made the decision to produce--based on the author's Executive MBA course in Business Ethics--a distance-delivered continuing education program for professional engineers and surveyors. Participants across the USA now may use the course to satisfy continuing education requirements with respect to professional licensing and certification. This paper outlines the purpose and content of the course and describes its production, distribution, application, and evaluation.

Commerce↗
PubMed2005

Topics and cases for online education in engineering.

When considering offering online education for engineering ethics instruction, making choices necessary for the effective development and delivery of an engineering ethics curriculum is an important first step. Selecting the topics and types of cases for the most effective ethics education of engineering students is a vital step in preparing an effective program. Examples are presented for topics which are considered good candidates for online presentation, and the adaptability of these topics for web-based instruction is discussed. Types of cases which are useful in engineering ethics education are presented. Methods of teaching applied ethics, as well as ideas for web-based ethics course design are suggested. The market for web-based instruction is discussed

Computer-Assisted Instruction↗
PubMed2006

Engineering ethics, individuals, and organizations.

This article evaluates a family of criticism of how engineering ethics is now generally taught. The short version of the criticism might be put this way: Teachers of engineering ethics devote too much time to individual decisions and not enough time to social context. There are at least six version of this criticism, each corresponding to a specific subject omitted. Teachers of engineering ethics do not (it is said) teach enough about: 1) the culture of organizations; 2) the organization of organizations; 3) the legal environment of organizations; 4) the role of professions in organizations; 5) the role of organizations in professions; or 6) the political environment of organizations. My conclusion is that, while all six are worthy subjects, there is neither much reason to believe that any of them are now absent from courses in engineering ethics nor an obvious way to decide whether they (individually or in combination) are (or are not) now being given their due. What we have here is a dispute about how much is enough. Such disputes are not to be settled without agreement concerning how we are to tell we have enough of this or that. Right now we seem to lack that agreement and not to have much reason to expect it any time soon.

Engineering↗