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At least 595 records · Page 33Linked to original sources
PubMed2005

[Therapeutic effect of tissue engineered tendon in repairing old calcaneal tendon rupture and defects].

OBJECTIVE: To probe into the surgical methods and therapeutic effect of repairing old calcaneal tendon rupture and defects with tissue engineered tendons. METHODS: The tissue engineered tendons were prefabricated by co-cultivating allogeneic tendon cells with composite of carbon fiber and polyglycolic acid for 5 days. From August 1999 to June 2002, 7 patients with calcaneal tendon rupture and defects (5-7 cm in length) were treated with tissue engineered tendons. The defects were repaired by suturing repeatedly with tissue engineered tendons. Meanwhile, the defects were covered by gastrocnemius fascial flap for protection and strengthening. After surgery, the ankle joints were fixed with plaster 4 to 6 weeks, and then the functional exercise was done. RESULTS: All the patients were followed up 22 to 56 months (46.9 months on average). Six patients achieved healing by the first intention, only one patient had delayed union. No local or systemic complication occurred in all the cases. No patients were given the second operation for adhesion. In accordance with YIN Qingshui's criterion for therapeutic effect, the results were excellent in 5 cases, good in 1 case and moderate in 1 case. CONCLUSION: Repairing old rupture and defects of calcaneal tendon with tissue engineered tendons can achieve good clinical outcome, it is an optional therapy.

Achilles Tendon↗
PubMed2005

Development and potential of a biomimetic chitosan/type II collagen scaffold for cartilage tissue engineering.

BACKGROUND: Damaged articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair. Creation of an appropriate cell carrier is one of the critical steps for successful tissue engineering. With the supposition that a biomimetic construct might promise to generate better effects, we developed a novel composite scaffold and investigated its potential for cartilage tissue engineering. METHODS: Chitosan of 88% deacetylation was prepared via a modified base reaction procedure. A freeze-drying process was employed to fabricate a three-dimensional composite scaffold consisting of chitosan and type II collagen. The scaffold was treated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. Ultrastructure and tensile strength of the matrix were carried out to assess its physico-chemical properties. After subcutaneous implantation in rabbits, its in vivo biocompatibility and degradability of the scaffold were determined. Its capacity to sustain chondrocyte growth and biosynthesis was evaluated through cell-scaffold co-culture in vitro. RESULTS: The fabricated composite matrix was porous and sponge-like with interconnected pores measuring from 100-250 microm in diameter. After cross-linking, the scaffold displayed enhanced tensile strength. Subcutaneous implantation results indicated the composite matrix was biocompatible and biodegradable. In intro cell-scaffold culture showed the scaffold sustained chondrocyte proliferation and differentiation, and maintained the spheric chondrocytic phenotype. As indicated by immunohistochemical staining, the chondrocytes synthesized type II collagen. CONCLUSIONS: Chitosan and type II collagen can be well blended and developed into a porous 3-D biomimetic matrix. Results of physico-chemical and biological tests suggest the composite matrix satisfies the constraints specified for a tissue-engineered construct and may be used as a chondrocyte carrier for cartilage tissue engineering.

Animals↗
PubMed2006

The experimental study of genetic engineering human neural stem cells mediated by lentivirus to express multigene.

OBJECTIVE: To explore the feasibility to construct genetic engineering human neural stem cells (hNSCs) mediated by lentivirus to express multigene in order to provide a graft source for further studies of spinal cord injury (SCI). METHODS: Human neural stem cells from the brain cortex of human abortus were isolated and cultured, then gene was modified by lentivirus to express both green fluorescence protein (GFP) and rat neurotrophin-3 (NT-3); the transgenic expression was detected by the methods of fluorescence microscope, dorsal root ganglion of fetal rats and slot blot. RESULTS: Genetic engineering hNSCs were successfully constructed. All of the genetic engineering hNSCs which expressed bright green fluorescence were observed under the fluorescence microscope. The conditioned medium of transgenic hNSCs could induce neurite flourishing outgrowth from dorsal root ganglion (DRG). The genetic engineering hNSCs expressed high level NT-3 which could be detected by using slot blot. CONCLUSIONS: Genetic engineering hNSCs mediated by lentivirus can be constructed to express multigene successfully.

Animals↗
PubMedDate not supplied

Tissue-engineered bone for lateral alveolar ridge augmentation: a case report.

Bone matrix derived from mandibular periosteal cells and cultivated by tissue engineering on a polymer fleece has recently been used for sinus floor elevation and augmentation. This case report focuses on clinical and histologic results after lateral ridge augmentation of a localized non-space maintaining defect in the right posterior area of the mandible using tissue-engineered bone. Implant supported prosthetic rehabilitation of a partially edentulous 32-year-old woman was planned involving a fixed partial denture. Preoperative investigations revealed a transversely reduced alveolar ridge width on the right side of the posterior mandible. Lateral augmentation was performed using tissue-engineered bone obtained by autogenous periosteum cells from the same area. Six months after augmentation 2 implants were placed and a bone biopsy was obtained from the augmented area. Transverse ridge dimensions were found to be enhanced. Histologic examination of the biopsy revealed dense lamellar bone. Wound healing was uneventful after all surgical interventions. This case report demonstrates the successful clinical application of tissue-engineered bone for lateral augmentation of the transversely reduced alveolar ridge. The results suggest that periosteum-derived tissue-engineered bone can be used to create a sufficient implant site not only for the sinus floor elevation and augmentation procedure for vertical bone enhancement but also for lateral augmentation.

Adult↗
PubMed2006

[Progress on engineered strains for ethanol production].

With the 21 century's coming, the era of cheap oil is coming to the end. There has been an increasing worldwide interest in fuel ethanol. In the last two decades, lots of work has been done to develop strains for ethanol producing. Research progress on metabolic engineering of strains for fuel ethanol production is summarized, including genetically engineered Saccharomyces cerevisiae to utilize starch, pentose and cellulose, Zymomonas mobilis to ferment arabinose and xylose, Escherichia coli and Klebsiella oxytoca to introduce heterogenous ethanol production pathway. The aim of engineering these strains is to obtain an ideal microorganism which can converse the available carbon sources to ethanol rapidly and efficiently with high tolerance to ethanol and to inhibitory components in the cheap materials such as lignocellulose hydrolysate. The importance of fuel ethanol will be a stimulus to develop engineered hardy strains to utilize cheap materials for high ethanol concentration production. Since both Saccharomyces cerevisiae and Zymomonas mobilis are generally regarded as safe (GRAS), genetically engineered Saccharomyces cerevisiae which can utilize raw starch directly and recombinant Zymomonas mobilis which can ferment glucose, arabinose and xylose in the lignocellulose hydrolysate have potential application to industry in the near future.

Biotechnology↗
PubMed1982

Biomedical engineering in cardiology.

There are numerous and quite controversial opinions on what should be covered by the term 'biomedical engineering'. Therefore, it seems necessary to define and reflect on what biomedical engineering really means. Our definition is: biomedical engineering is the application of engineering sciences in clinical medicine. Several examples of 10 years of cooperation between engineers and physicians in Aachen are presented under the confines of the above definition.

Animals↗
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↗
PubMedDate not supplied

The burned-out clinical engineer.

Considerable stress can be induced within hospital-based clinical engineers whenever unrealized expectations combine with a dynamic, goal-oriented personality. Unmanaged, this stress becomes the mental overload that eventually burns these clinical engineers out. As a result, in part, clinical engineering is losing its most valuable resource; for as clinical engineers( and BMETs) burn out, they tend to migrate from the hospital to industry, taking a wealth of talent and leadership with them. Understanding the etiology of clinical engineering burnout and its symptoms can alert personnel to modify expectations and life-styles to cope with the problem. Prevention techniques include self-awareness of expectations and needs, vacations, peer group discussions, outside interests-and ultimately job or career changes.

Biomedical Engineering↗
PubMed1998

Tissue engineering: the first decade and beyond.

This article reviews the important developments in the field of tissue engineering over the last 10 years. Research in the area of biomaterials is examined from the perspective of providing the foundation for the development of tissue engineering. Early efforts combining cells with biocompatible materials are described and applications of this technology presented, with particular focus on uses in orthopaedics and maxillofacial surgery. The basic principles of tissue engineering and state-of-the-art technology in cell biology and materials science as used currently in the field are presented. Finally, futures challenges are outlined from the perspective of integrating technologies from medicine, biology, and engineering, in hopes of translating tissue engineering to clinical applications.

Animals↗
PubMed2005

Global physiological understanding and metabolic engineering of microorganisms based on omics studies.

Through metabolic engineering, scientists seek to modify the metabolic pathways of living organisms to facilitate optimized, efficient production of target biomolecules. During the past decade, we have seen notable improvements in biotechnology, many of which have been based on metabolically engineered microorganisms. Recent developments in the fields of functional genomics, transcriptomics, proteomics, and metabolomics have changed metabolic engineering strategies from the local pathway level to the whole system level. This article focuses on recent advances in the field of metabolic engineering, which have been powered by the combined approaches of the various "omics" that allow us to understand the microbial metabolism at a global scale and to develop more effectively redesigned metabolic pathways for the enhanced production of target bioproducts.

Biomedical Engineering↗
PubMed2025

Hierarchical metabolic engineering for rewiring cellular metabolism.

Metabolic engineering is a key enabling technology for rewiring cellular metabolism to enhance production of chemicals, biofuels, and materials from renewable resources. However, how to make cells into efficient factories is still challenging due to its robust metabolic networks. To open this door, metabolic engineering has realized great breakthroughs through three waves of technological research and innovations, especially the third wave. To understand the third wave of metabolic engineering better, we discuss its mainstream strategies and examples of its application at five hierarchies, including part, pathway, network, genome, and cell level, and provide insights as to how to rewire cellular metabolism in the context of maximizing product titer, yield, and productivity. Finally, we highlight future perspectives on metabolic engineering for the successful development of cell factories.

Metabolic Engineering↗
PubMed2004

Occupational exposure to diesel and gasoline engine exhausts and risk of lung cancer among Finnish workers.

BACKGROUND: Studies on engine exhausts and lung cancer have given inconsistent results. METHODS: Economically active Finns were followed-up for lung cancer during 1971-95 (33,664 cases). Their Census occupations in 1970 were converted to exposures to diesel and gasoline engine exhausts with a job-exposure matrix. The relative risks (RRs) for cumulative exposure (CE) were defined by Poisson regression, adjusted for smoking, asbestos, and quartz dust exposure, and socioeconomic status. RESULTS: RR for engine exhausts among men did not increase with increasing CE. In women, RR for gasoline engine exhaust was 1.58 (95% CI 1.10-2.26) in the CE-category of 1-99 mg/m(3)-y and 1.66 (1.11-2.50) among those with > or =100 mg/m(3)-y (lag 20 years). With a lag of 10 years RR for the middle/highest diesel exhaust category in women was 1.42 (0.94-2.13). CONCLUSIONS: Occupational exposure to engine exhausts was not consistently associated with lung cancer in this study, possibly due to low exposure levels.

Adult↗
PubMed2007

Shape-engineered fibroblasts: cell elasticity and actin cytoskeletal features characterized by fluorescence and atomic force microscopy.

The regulation of cell shape, which determines cell behaviors including adhesion, spreading, migration, and proliferation in an engineered artificial extracellular milieu, is an important task in tissue engineering and in development of functional biomaterials. To deepen the understandings of shape-dependent cell mechanics, the cell elasticity and structural features of the actin cytoskeleton (CSK) were characterized for shape-engineered fibroblasts; round and spindle-shaped cells cultured on photolithographically microprocessed surfaces, employing the cellular microindentation tests and fluorescence observation of actin CSK by the combination of atomic force microscopy (AFM) and fluorescence microscopy (FM). The relationships among cell elasticity, the structural features of actin CSK, and engineered cell shape were analyzed and compared with those of control cells that had been cultured on nonprocessed surfaces (termed naturally extended cells). Results showed that the spindle-shaped cells with sparse or no apical stress fibers (ASFs) exhibited similar stiffness to that of the naturally extended cells with dense ASFs. The elasticity of spindle-shaped cells was affected only slightly by the stress fiber (SF) density, which is in marked contrast to the significant correlation shown between cell elasticity and SF density in naturally extended cells. This result implies that the elasticity of regionally restricted adhesion-surface-induced shape-engineered cells, particularly of highly elongated cells, is affected predominantly by cell shape rather than by structural features of SFs.

3T3 Cells↗
PubMed1996

Cancer incidence among male railway engine-drivers and conductors in Sweden, 1976-90.

During recent years, the relationship between exposure to magnetic fields and cancer has attracted increasing interest. In Sweden, train personnel are exposed to comparatively strong magnetic fields in their work. The aim of the present study was to investigate cancer incidence, particularly leukemia and brain tumors, among male railway engine drivers and conductors, respectively, and to compare their cancer incidence with that of the general male population. The study population comprised all male railway engine drivers (n = 7,466) and conductors (n = 2,272) who were ever employed at the Swedish State Railways during the period 1976-90. The study population was observed with regard to cancer incidence by means of the National Cancer Register for the period 1976-90. The total cancer incidence (all tumors included) among railway engine drivers was lower than in the general Swedish population. An increased incidence of lymphocytic leukemia was observed among railway engine drivers and conductors combined (relative risk = 2.3; 95 percent confidence interval = 1.3-3.2), with the same point estimate for both occupational groups. For brain tumor (astrocytoma), the observed relative risk was close to one. The study provides evidence of an excess risk of lymphocytic leukemia in railway engine drivers and conductors, workers with known occupational exposure to magnetic fields.

Adult↗
PubMed1991

Evaluating the human engineering of microprocessor-controlled operating room devices.

Although human engineering features are widely appreciated as a potential cause of operating room incidents, evaluating the human engineering features of devices is not widely understood. Standards, guidelines, laboratory and field testing, and engineering discipline are all proposed methods for improving the human engineering of devices. New microprocessor technology offers designers great flexibility in the design of devices, but this flexibility is often coupled with complexity and more elaborate user interaction. Guidelines and standards usually do not capture these features of new equipment, in part because technology improvements occur faster than meaningful guidelines can be developed. Professional human engineering of new devices relies on a broad, user-centered approach to design and evaluation. Used in the framework of current knowledge about human operator performance, these techniques offer guidance to new equipment designers and to purchasers and users of these devices.

Anesthesiology↗
PubMed1999

Joint cartilage regeneration by tissue engineering.

The research field of tissue engineering combines cells biology, biomaterial science, and surgery. Major long-term goals are tissue and organ replacement therapies using the patients' own cells. Our work is focused on the treatment of severe joint defects and on plastic surgery using in vitro engineered cartilage tissues. The practical approaches in cartilage engineering face problems with three-dimensional cell distribution or cell immobilization raising biocompatibility problems. The tissue engineering of cartilage is based on combining biocompatible cell embedding substances such as fibrin, agarose, alginate, hyaluronic acid and fiber fleece scaffolds of poly alpha-hydroxy acids (PLLA/PGLA). Different technical approaches were established: a) three-dimensional in vitro cultures of chondrocytes for the development of vital tissue transplants and b) interacting three-dimensional cultures consisting of different cell populations, such as BMP-transfected mesenchymal cells. The preshaped artificial tissue constructs were cultured in perfusion chambers to maintain a stable diffusion of nutrients during the in vitro pre-formation step. Subsequently, pre-formed tissues were implanted into nude mice and into 4 mm articular joint defects of rabbits. Transplants were found to produce cartilage typic morphological patterns and matrix. 80% of the transplants remained stable in vivo. However, 20% of the tissues are resorbed or replaced by a fibrous tissue. These results demonstrate that current artificial cartilage transplants are already feasible for plastic reconstruction. The treatment of severe joint defects, however, faces additional problems which are addressed in ongoing studies: (a) the fixation of engineered cartilage in joints, (b) the protection against chronic inflammatory degradation, and (c) the required enormous mechanical stability.

Animals↗
PubMed2000

Can a tissue-engineered skin graft improve healing of lower extremity foot wounds after revascularization?

A bilayered tissue-engineered skin graft composed of human neonatal foreskin fibroblasts and keratinocytes in a type I bovine collagen matrix has been developed. We sought to determine if this graft improves wound healing after lower extremity revascularization. Thirty-one previously ischemic foot wounds were randomly assigned to moist dressing changes or tissue-engineered skin graft within 60 days of revascularization. In the grafted group, 10 received meshed and 11 received unmeshed graft. Wound healing was followed by wound area measurements and photography. There were no statistically significant differences between groups in patient age, sex, diabetes or renal failure risk factors, revascularization procedure, or wound location or size. Treatment with tissue-engineered skin graft was significantly more effective than moist dressing in the percentage of wounds healed (62 vs. 0% at 8 weeks, 86 vs. 40% at 12 weeks, p < 0.01) and the median time to complete wound closure (7 vs. 15 weeks, p = 0.0021, rank-sum test). There was no difference in the wound closure rate of meshed and unmeshed graft at 4, 8, 12, or 24 weeks (p > 0.05). Three indolent localized wound infections in the tissue-engineered skin graft group were the only complication. Tissue-engineered skin grafting can be used safely in previously ischemic wounds after lower extremity revascularization. Treatment with this graft promotes healing more rapidly and in more patients than standard moist dressings. It obviates the risk, inconvenience, and expense of donor skin harvesting, anesthesia, and hospitalization associated with autologous skin grafting. This graft may represent an advance in the treatment of previously ischemic lower extremity foot wounds.

Aged↗
PubMed1992

Industrial safety engineering--challenges of the future.

Safety management is now entering an era quite different to that which marked its foundation. The multiple challenges facing safety engineering are focused upon. In the United States, France, Britain, and Brazil, safety engineering has experienced fast growth over the past two decades. An increased questioning of the traditional assumptions of the profession in both traditional and postindustrial work has accompanied this growth. New directions of reflection and research are being pursued. Recent research in sociology, where worker perceptions of tasks and their dangers are incorporated into the analysis of accident production, brings promising but still incipient new perspectives to accident research and theory. Simultaneously, novel challenges for safety engineering are posed by the emergence of postindustrial technologies. Some of these threaten large civilian populations, and the knowledge is not currently available to guarantee accident prevention. In this way the responsibilities of safety engineering, both ethical and with regards the provision of information to the public, are brought under the spotlight. The face of safety engineering is being changed.

Accident Prevention↗