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At least 433 records · Page 24Linked to original sources
PubMed2000

[Development of domain specific search engines].

As cyber space exploding in a pace that nobody has ever imagined, it becomes very important to search cyber space efficiently and effectively. One solution to this problem is search engines. Already a lot of commercial search engines have been put on the market. However these search engines respond with such cumbersome results that domain specific experts can not tolerate. Using a dedicate hardware and a commercial software called OpenText, we have tried to develop several domain specific search engines. These engines are for our institute's Web contents, drugs, chemical safety, endocrine disruptors, and emergent response for chemical hazard. These engines have been on our Web site for testing.

Computers↗
PubMed2004

[Biomedical information on the internet using search engines. A one-year trial].

The internet is a communication medium and content distributor that provide information in the general sense but it could be of great utility regarding as the search and retrieval of biomedical information. Search engines represent a great deal to rapidly find information on the net. However, we do not know whether general search engines and meta-search ones are reliable in order to find useful and validated biomedical information. The aim of our study was to verify the reproducibility of a search by key-words (pediatric or evidence) using 9 international search engines and 1 meta-search engine at the baseline and after a one year period. We analysed the first 20 citations as output of each searching. We evaluated the formal quality of Web-sites and their domain extensions. Moreover, we compared the output of each search at the start of this study and after a one year period and we considered as a criterion of reliability the number of Web-sites cited again. We found some interesting results that are reported throughout the text. Our findings point out an extreme dynamicity of the information on the Web and, for this reason, we advice a great caution when someone want to use search and meta-search engines as a tool for searching and retrieve reliable biomedical information. On the other hand, some search and meta-search engines could be very useful as a first step searching for defining better a search and, moreover, for finding institutional Web-sites too. This paper allows to know a more conscious approach to the internet biomedical information universe.

Information Storage and Retrieval↗
PubMed1985

Noise exposure levels from model airplane engines.

Previous research indicates that noise levels from unmuffled model airplane engines produce sufficient noise to cause TTS. The present study explored SPLs of smaller engines under 3.25 cc (.19 cu. in.) and the effectiveness of engine mufflers. Results showed that model airplanes can exceed a widely used damage risk criterion (DRC) but that engine mufflers can reduce levels below DRC. Handling model gasoline engines should be added to the list of recreational activities such as snow-mobile and motorcycle riding, shooting, etc. in which the participant's hearing may be in jeopardy. Suggestions are presented to the model engine enthusiast for avoiding damage to hearing.

Aircraft↗
PubMed2007

Gene-modified tissue-engineered skin: the next generation of skin substitutes.

Tissue engineering combines the principles of cell biology, engineering and materials science to develop three-dimensional tissues to replace or restore tissue function. Tissue engineered skin is one of most advanced tissue constructs, yet it lacks several important functions including those provided by hair follicles, sebaceous glands, sweat glands and dendritic cells. Although the complexity of skin may be difficult to recapitulate entirely, new or improved functions can be provided by genetic modification of the cells that make up the tissues. Gene therapy can also be used in wound healing to promote tissue regeneration or prevent healing abnormalities such as formation of scars and keloids. Finally, gene-enhanced skin substitutes have great potential as cell-based devices to deliver therapeutics locally or systemically. Although significant progress has been made in the development of gene transfer technologies, several challenges have to be met before clinical application of genetically modified skin tissue. Engineering challenges include methods for improved efficiency and targeted gene delivery; efficient gene transfer to the stem cells that constantly regenerate the dynamic epidermal tissue; and development of novel biomaterials for controlled gene delivery. In addition, advances in regulatable vectors to achieve spatially and temporally controlled gene expression by physiological or exogenous signals may facilitate pharmacological administration of therapeutics through genetically engineered skin. Gene modified skin substitutes are also employed as biological models to understand tissue development or disease progression in a realistic three-dimensional context. In summary, gene therapy has the potential to generate the next generation of skin substitutes with enhanced capacity for treatment of burns, chronic wounds and even systemic diseases.

Animals↗
PubMed2006

Surface engineering approaches to micropattern surfaces for cell-based assays.

The ability to produce patterns of single or multiple cells through precise surface engineering of cell culture substrates has promoted the development of cellular bioassays that provide entirely new insights into the factors that control cell adhesion to material surfaces, cell proliferation, differentiation and molecular signaling pathways. The ability to control shape and spreading of attached cells and cell-cell contacts through the form and dimension of the cell-adhesive patches with high precision is important. Commitment of stem cells to different specific lineages depends strongly on cell shape, implying that controlled microenvironments through engineered surfaces may not only be a valuable approach towards fundamental cell-biological studies, but also of great importance for the design of cell culture substrates for tissue engineering. Furthermore, cell patterning is an important tool for organizing cells on transducers for cell-based sensing and cell-based drug discovery concepts. From a material engineering standpoint, patterning approaches have greatly profited by combining microfabrication technologies, such as photolithography, with biochemical functionalization to present to the cells biological cues in spatially controlled regions where the background is rendered non-adhesive ("non-fouling") by suitable chemical modification. The focus of this review is on the surface engineering aspects of biologically motivated micropatterning of two-dimensional (flat) surfaces with the aim to provide an introductory overview and critical assessment of the many techniques described in the literature. In particular, the importance of non-fouling surface chemistries, the combination of hard and soft lithography with molecular assembly techniques as well as a number of less well known, but useful patterning approaches, including direct cell writing, are discussed.

Adsorption↗
PubMed2006

Mineralization capacity of Runx2/Cbfa1-genetically engineered fibroblasts is scaffold dependent.

Development of tissue-engineered constructs for skeletal regeneration of large critical-sized defects requires the identification of a sustained mineralizing cell source and careful optimization of scaffold architecture and surface properties. We have recently reported that Runx2-genetically engineered primary dermal fibroblasts express a mineralizing phenotype in monolayer culture, highlighting their potential as an autologous osteoblastic cell source which can be easily obtained in large quantities. The objective of the present study was to evaluate the osteogenic potential of Runx2-expressing fibroblasts when cultured in vitro on three commercially available scaffolds with divergent properties: fused deposition-modeled polycaprolactone (PCL), gas-foamed polylactide-co-glycolide (PLGA), and fibrous collagen disks. We demonstrate that the mineralization capacity of Runx2-engineered fibroblasts is scaffold dependent, with collagen foams exhibiting ten-fold higher mineral volume compared to PCL and PLGA matrices. Constructs were differentially colonized by genetically modified fibroblasts, but scaffold-directed changes in DNA content did not correlate with trends in mineral deposition. Sustained expression of Runx2 upregulated osteoblastic gene expression relative to unmodified control cells, and the magnitude of this expression was modulated by scaffold properties. Histological analyses revealed that matrix mineralization co-localized with cellular distribution, which was confined to the periphery of fibrous collagen and PLGA sponges and around the circumference of PCL microfilaments. Finally, FTIR spectroscopy verified that mineral deposits within all Runx2-engineered scaffolds displayed the chemical signature characteristic of carbonate-containing, poorly crystalline hydroxyapatite. These results highlight the important effect of scaffold properties on the capacity of Runx2-expressing primary dermal fibroblasts to differentiate into a mineralizing osteoblastic phenotype for bone tissue engineering applications.

Animals↗
PubMed2006

Carbon nanotube applications for tissue engineering.

As the field of tissue engineering advances, new tools for better monitoring and evaluating of engineered tissues along with new biomaterials to direct tissue growth are needed. Carbon nanotubes may be an important tissue engineering material for improved tracking of cells, sensing of microenvironments, delivering of transfection agents, and scaffolding for incorporating with the host's body. Using carbon nanotubes for optical, magnetic resonance and radiotracer contrast agents would provide better means of evaluating tissue formation. In addition, monitoring and altering intra and intercellular processes would be useful for design of better engineered tissues. Carbon nanotubes can also be incorporated into scaffolds providing structural reinforcement as well as imparting novel properties such as electrical conductivity into the scaffolds may aid in directing cell growth. Potential cytotoxic effects associated with carbon nanotubes may be mitigated by chemically functionalizing the surface. Overall, carbon nanotubes may play an integral role as unique biomaterial for creating and monitoring engineered tissue.

Animals↗
PubMedDate not supplied

Ethical responsibilities of the clinical engineer.

Because of the growth of medical technology, Clinical Engineers have increased responsibilities in respect to this new technology and so to modern medicine itself. This results in a need to ensure that an ethical consciousness of responsibilities to patients, physicians, and institutions grows within Clinical Engineers as they move into evermore important roles within the health care system. Clinical Engineers must have clearly defined roles, as well as authority acknowledged and supported by other health care professionals. Most importantly, Clinical Engineers themselves must recognize the seriousness of their professional responsibilities as they contribute to the maintenance of equipment, use and design instrumentation, and fulfill roles in administration, management, and research. As members of the health care team, Clinical Engineers must be prepared to face ethical issues arising from defective or inadequate equipment, hazards and incidents, scarcity and resources, conflict of interest, confidentiality, clinical research, "truth-telling," and care of the terminally ill.

Biomedical Engineering↗
PubMedDate not supplied

Am empirical study of selected cost measures of clinical engineering service effectiveness.

The growing demand for more and better healthcare service greatly expands the role of medical equipment in providing health services more effectively. The purpose of introducing clinical engineering programs in hospitals was to improve the effectiveness of healthcare institutions' utilization and management of medical technology. Over the last decade, the role of clinical engineering has grown in importance as a component of hospitals and the healthcare delivery system. Hospital administrators currently put a strong emphasis on cost effectiveness of clinical engineering services, to reduce the cost of acquisition and maintenance of equipment. Unfortunately, the lack of a commonly accepted definition of cost effectiveness has resulted in a certain amount of confusion over how the performance of clinical engineering services can or should be measured. The results presented in this paper should assist hospital administrators and clinical engineering program managers to establish a common understanding of what "cost effectiveness" means and how it can be achieved.

Biomedical Engineering↗
PubMedDate not supplied

Multi-level educational affiliations for a CE (clinical engineer) department.

Educational programs for clinical engineers and biomedical equipment technicians should provide students with an exposure to the clinical environment. Through alliances with educational institutions, hospitals can assist future engineers and technicians in obtaining a well-rounded education. These affiliations provide a hospital with engineering expertise for research projects, as well as a resource for the clinical engineering department. One hospital, Baystate Medical Center in Springfield, Massachusetts, has successfully developed internships for technician candidates in an Associate's degree program and for undergraduate and graduate engineering students through educational affiliations with three different academic institutions. The internships of the students intertwine, giving them a unique educational experience.

Biomedical Engineering↗
PubMed2005

Tissue engineering.

PURPOSE OF REVIEW: Regenerative medicine holds promise for the restoration of tissues and organs damaged by wear, trauma, neoplasm, or congenital deformity. Tissue engineering combines the disciplines of cell biology and biomedical engineering to effect the design and maturation of various tissues. Despite progress in some areas of tissue regeneration, there has not been significant translation to clinical practice. This article reviews the present understanding of and advances in regenerative medicine, as well as describing limitations in current techniques and areas that need further development. A discussion of the state of the art in the regeneration of skin, cartilage, bone, adipose tissue, and neural tissue is included. RECENT FINDINGS: Differences between extracorporeal and in-vitro tissue engineering are discussed, as well as tissue engineering principles, including the use of bioactive scaffolds, progenitor cells and stem cells, the need for cellular and tissue patterning, microcirculation development, and the use of external stimuli for differentiation. Much needs to be learned about progenitor cell biology, cell-cell interactions, cellular interactions with the extracellular matrix, and about the cues needed for differentiation of functional tissues. SUMMARY: The current limitations in regenerative medicine techniques and the gaps in current knowledge of cellular biology and tissue development represent significant research opportunities in tissue engineering.

Biomedical Engineering↗
PubMed2025

Turbo-charging crop improvement: harnessing multiplex editing for polygenic trait engineering and beyond.

Multiplex CRISPR editing has emerged as a transformative platform for plant genome engineering, enabling the simultaneous targeting of multiple genes, regulatory elements, or chromosomal regions. This approach is effective for dissecting gene family functions, addressing genetic redundancy, engineering polygenic traits, and accelerating trait stacking and de novo domestication. Its applications now extend beyond standard gene knockouts to include epigenetic and transcriptional regulation, chromosomal engineering, and transgene-free editing. These capabilities are advancing crop improvement not only in annual species but also in more complex systems such as polyploids, undomesticated wild relatives, and species with long generation times. At the same time, multiplex editing presents technical challenges, including complex construct design and the need for robust, scalable mutation detection. We discuss current toolkits and recent innovations in vector architecture, such as promoter and scaffold engineering, that streamline workflows and enhance editing efficiency. High-throughput sequencing technologies, including long-read platforms, are improving the resolution of complex editing outcomes such as structural rearrangements-often missed by standard genotyping-when targeting repetitive or tandemly spaced loci. To fully realize the potential of multiplex genome engineering, there is growing demand for user-friendly, synthetic biology-compatible, and scalable computational workflows for gRNA design, construct assembly, and mutation analysis. Experimentally validated inducible or tissue-specific promoters are also highly desirable for achieving spatiotemporal control. As these tools continue to evolve, multiplex CRISPR editing is poised to become a foundational technology of next-generation crop improvement to address challenges in agriculture, sustainability, and climate resilience.

Gene Editing↗
PubMed2005

Evolutionary programming as a platform for in silico metabolic engineering.

BACKGROUND: Through genetic engineering it is possible to introduce targeted genetic changes and hereby engineer the metabolism of microbial cells with the objective to obtain desirable phenotypes. However, owing to the complexity of metabolic networks, both in terms of structure and regulation, it is often difficult to predict the effects of genetic modifications on the resulting phenotype. Recently genome-scale metabolic models have been compiled for several different microorganisms where structural and stoichiometric complexity is inherently accounted for. New algorithms are being developed by using genome-scale metabolic models that enable identification of gene knockout strategies for obtaining improved phenotypes. However, the problem of finding optimal gene deletion strategy is combinatorial and consequently the computational time increases exponentially with the size of the problem, and it is therefore interesting to develop new faster algorithms. RESULTS: In this study we report an evolutionary programming based method to rapidly identify gene deletion strategies for optimization of a desired phenotypic objective function. We illustrate the proposed method for two important design parameters in industrial fermentations, one linear and other non-linear, by using a genome-scale model of the yeast Saccharomyces cerevisiae. Potential metabolic engineering targets for improved production of succinic acid, glycerol and vanillin are identified and underlying flux changes for the predicted mutants are discussed. CONCLUSION: We show that evolutionary programming enables solving large gene knockout problems in relatively short computational time. The proposed algorithm also allows the optimization of non-linear objective functions or incorporation of non-linear constraints and additionally provides a family of close to optimal solutions. The identified metabolic engineering strategies suggest that non-intuitive genetic modifications span several different pathways and may be necessary for solving challenging metabolic engineering problems.

Algorithms↗
PubMed2005

Quantitative ultrasound can assess the regeneration process of tissue-engineered cartilage using a complex between adherent bone marrow cells and a three-dimensional scaffold.

Articular cartilage (hyaline cartilage) defects resulting from traumatic injury or degenerative joint disease do not repair themselves spontaneously. Therefore, such defects may require novel regenerative strategies to restore biologically and biomechanically functional tissue. Recently, tissue engineering using a complex of cells and scaffold has emerged as a new approach for repairing cartilage defects and restoring cartilage function. With the advent of this new technology, accurate methods for evaluating articular cartilage have become important. In particular, in vivo evaluation is essential for determining the best treatment. However, without a biopsy, which causes damage, articular cartilage cannot be accurately evaluated in a clinical context. We have developed a novel system for evaluating articular cartilage, in which the acoustic properties of the cartilage are measured by introducing an ultrasonic probe during arthroscopy of the knee joint. The purpose of the current study was to determine the efficacy of this ultrasound system for evaluating tissue-engineered cartilage in an experimental model involving implantation of a cell/scaffold complex into rabbit knee joint defects. Ultrasonic echoes from the articular cartilage were converted into a wavelet map by wavelet transformation. On the wavelet map, the percentage maximum magnitude (the maximum magnitude of the measurement area of the operated knee divided by that of the intact cartilage of the opposite, nonoperated knee; %MM) was used as a quantitative index of cartilage regeneration. Using this index, the tissue-engineered cartilage was examined to elucidate the relations between ultrasonic analysis and biochemical and histological analyses. The %MM increased over the time course of the implant and all the hyaline-like cartilage samples from the histological findings had a high %MM. Correlations were observed between the %MM and the semiquantitative histologic grading scale scores from the histological findings. In the biochemical findings, the chondroitin sulfate content increased over the time course of the implant, whereas the hydroxyproline content remained constant. The chondroitin sulfate content showed a similarity to the results of the %MM values. Ultrasonic measurements were found to predict the regeneration process of the tissue-engineered cartilage as a minimally invasive method. Therefore, ultrasonic evaluation using a wavelet map can support the evaluation of tissue-engineered cartilage using cell/scaffold complexes.

Animals↗
PubMed2003

[Research advances in gene-enhanced tissue engineering].

Gene-enhanced engineering deals with the scientific and technologic endeavour to produce cultured cells or polymer matrices transduced with multiple gene vectors encoding cytokine cDNA by means of genetic engineering technique, to make transduced cells or gene activated matrices highly express according cytokine, and then to enhance certain abilities of the artificial tissue. Up to now, various genes encoding modulatory species of ribonucleic of proteins such as growth factors, receptors, and transcription factors have been used in the context of gene-enhanced tissue engineering and expressed within numerous tissues, including artificial blood vessels, bone, cartilage, skin and urinary system, etc. Many experiments in vitro or in vivo have begun to show good prospects and great potential application of the new approach. We believe great changes will take place in the research field of tissue engineering due to the induction the of genetic engineering, and the new approach will become a very promising and valuable tool for therapy.

Blood Vessel Prosthesis↗
PubMed1998

Engineering smooth muscle tissue with a predefined structure.

Nonwoven meshes of polyglycolic acid (PGA) fibers are attractive synthetic extracellular matrices (ECMs) for tissue engineering and have been used to engineer many types of tissues. However, these synthetic ECMs lack structural stability and often cannot maintain their original structure during tissue development. This makes it difficult to design an engineered tissue with a predefined configuration and dimensions. In this study, we investigated the ability of PGA fiber-based matrices bonded at their fiber crosspoints with a secondary polymer, poly-L-lactic acid (PLLA), to resist cellular contractile forces and maintain their predefined structure during the process of smooth muscle (SM) tissue development in vitro. Physically bonded PGA matrices exhibited a 10- to 35-fold increase in the compressive modulus over unbonded PGA matrices, depending on the mass of PLLA utilized to bond the PGA matrices. In addition, the bonded PGA matrices degraded much more slowly than the unbonded matrices. The PLLA bonding of PGA matrices had no effect on the ability of cells to adhere to the matrices. After 7 weeks in culture, the bonded matrices maintained 101 +/- 4% of their initial volume and an approximate original shape while the unbonded matrices contracted to 5 +/- 1% of their initial volume with an extreme change in their shape. At this time the bonded PGA matrices had a high cellularity, with smooth muscle cells (SMCs) and ECM proteins produced by these cells (e.g., elastin) filling the pores between PGA fibers. This study demonstrated that physically bonded PGA fiber-based matrices allow the maintenance of the configuration and dimensions of the original matrices and the development of a new tissue in a predefined three-dimensional structure. This approach may be useful for engineering a variety of tissues of various structures and shapes, and our study demonstrates the importance of matching both the initial mechanical properties and the degradation rate of a matrix to the specific tissue one is engineering.

Animals↗
PubMed2003

Differentiated chondrocytes for cartilage tissue engineering.

Trauma to the articular cartilage surface of the joint represents a challenging clinical problem due to the very limited ability of this tissue to self-repair. Moreover, repair techniques such as microfracture, which introduce cells into the joint, have unpredictable clinical outcomes as they produce a fibrocartilage tissue that degenerates with time. Alternative treatments include tissue reconstruction with autograft and allograft tissue. However, these procedures are restricted by the availability of suitable donor tissue. These limitations have been the driving force behind the emerging field of articular cartilage tissue engineering. This paper will highlight and contrast the key challenges associated with the tissue engineering of this neo-tissue using differentiated adult cells. The various components of the tissue engineering process will be described including the choice of donor cell/tissue type and the selection of scaffolds that guide the formation of tissue. The ability of the tissue engineered implants to stimulate the repair of defects in vivo will also be discussed. Tissue engineering approaches may, in the future, provide an ideal alternative to the current surgical treatments for cartilage repair.

Adult↗
PubMed2001

Tissue engineering strategies for adipose tissue repair.

Tissue engineering is a relatively young field that combines engineering, clinical science, and life sciences to, in part, repair or regrow tissues. Adipose tissue has recently become a focus area for tissue engineering, encouraged by the large number of reconstructive, cosmetic, and correctional indications that could be addressed with clinically translatable adipose tissue engineering strategies. This review discusses the three aspects of an adipose construct, namely cell types, scaffold, and microenvironment, and presents current tissue engineering strategies under pursuit.

Adipose Tissue↗