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At least 649 records · Page 36Linked to original sources
PubMed2001

Tissue engineering's impact on dentistry.

Tissue engineering is a novel and exciting field that aims to re-create functional, healthy tissues and organs in order to replace diseased, dying, or dead tissues. The field has developed due to the inadequate supply of organs and tissues for patients requiring organ and tissue replacement. The following review first describes three major tissue engineering strategies. Although similar in their objectives, these strategies each maintain a unique component. Next, several examples of preclinical and clinical progress engineering oral-maxillofacial tissues are presented. Each of these examples highlights specific tissue engineering applications to different tissues of the oral-maxillofacial apparatus. Finally, practical implications are addressed as well as challenges that must be met in order for tissue engineering to reach its full potential.

Biocompatible Materials↗
PubMed2002

An assessment of the visibility of MeSH-indexed medical web catalogs through search engines.

Manually indexed Internet health catalogs such as CliniWeb or CISMeF provide resources for retrieving high-quality health information. Users of these quality-controlled subject gateways are most often referred to them by general search engines such as Google, AltaVista, etc. This raises several questions, among which the following: what is the relative visibility of medical Internet catalogs through search engines? This study addresses this issue by measuring and comparing the visibility of six major, MeSH-indexed health catalogs through four different search engines (AltaVista, Google, Lycos, Northern Light) in two languages (English and French). Over half a million queries were sent to the search engines; for most of these search engines, according to our measures at the time the queries were sent, the most visible catalog for English MeSH terms was CliniWeb and the most visible one for French MeSH terms was CISMeF.

Abstracting and Indexing↗
PubMed2003

Intratumoral delivery of dendritic cells engineered to secrete both interleukin (IL)-12 and IL-18 effectively treats local and distant disease in association with broadly reactive Tc1-type immunity.

Dendritic cells (DCs) were adenovirally engineered to constitutively and durably secrete the potent Th1-biasing cytokines interleukin (IL)-12 (AdIL12DC) and/or IL-18 (AdIL18DC) and evaluated for their ability to promote therapeutic antitumor immunity in murine sarcoma models. Injection of either AdIL12DC or AdIL18DC into day 7 CMS4 or MethA tumors resulted in tumor rejection or slowed tumor growth when compared with control cohorts. Importantly, intratumoral injection with DCs engineered to secrete both IL-12 and IL-18 (AdIL12/IL18DC) resulted in complete and the most acute rejection of any treatment group analyzed. This strategy was also effective in promoting the regression of contralateral, untreated tumors. Both CD4+ and CD8+ T cells were required for tumor rejection. CD8+ splenic T cells from mice treated with AdIL12/IL18DC produced the highest levels of IFN-gamma in response to tumor rechallenge in vitro and displayed the broadest repertoire of Tc1-type reactivity to acid-eluted, tumor-derived peptides among all treatment cohorts. This apparent enhancement in cross-presentation of tumor-associated epitopes in vivo may result from the increased capacity of engineered DCs to kill tumor cells, survive tumor-induced apoptosis, and present immunogenic MHC/tumor peptide complexes to T cells after intratumoral injection. In support of this hypothesis, cytokine gene-engineered DCs expressed higher levels of MHC and costimulatory molecules, as well as Fas ligand and membrane-bound tumor necrosis factor alpha, with the latter markers associated with elevated tumoricidal activity in vitro. Cytokine gene-engineered DCs appeared to have a survival advantage in situ when injected into tumor lesions, to be found in approximation with regions of tumor apoptosis, and to have the capacity to ingest apoptotic tumor bodies. These results support the ability of combined cytokine gene transfer to enhance multiple effector functions mediated by intralesionally injected DCs that may concertedly promote cross-priming and the accelerated immune-mediated rejection of tumors.

Adenoviridae↗
PubMed2004

A first look at HealthCyberMap medical semantic subject search engine.

HealthCyberMap (http://healthcybermap.semanticweb.org) is a Semantic Web project that aims at mapping selected parts of health information resources in cyberspace in novel semantic ways to improve their retrieval and navigation. This paper describes HealthCyberMap semantic subject search engine methodology and early prototype which attempt to overcome the limitations of conventional free text search engines. Explicit concepts in resource metadata map onto a brokering domain ontology (a clinical terminology or classification) allowing a Semantic Web search engine to infer implicit meanings (synonyms and semantic relationships) not directly mentioned in either the resource or its metadata. Similarly, user queries would map to the same ontology allowing the search engine to infer the implicit semantics of user queries and use them to optimise retrieval. Related issues of metadata, clinical terminologies and automatic vs. manual indexing of medical Web resources are also discussed, together with future methodological directions, which include the use of a true terminology server as an intelligent broker between user queries and HealthCyberMap pool of resource metadata. A comparative evaluation of the new engine based on relevance metrics is also proposed.

Humans↗
PubMed2004

[Assessment of acoustic environment and its effect on hearing in jet engine technical personnel].

BACKGROUND: Noise produced by jet engines may be harmful to aircraft servicing personnel because of high levels of acoustic pressure. The aim of the study was to assess the acoustic environment of persons exposed to jet engine noise and its effect on hearing. MATERIALS AND METHODS: Noise measurements were performed on three jet engines. During the target practice, the following parameters were measured: equivalent noise, pressure level A, maximum sound pressure level A, and peak sound pressure level C. The spectro-analysis covering the range from 0.1 to 20 kHz was conducted. Hearing was assessed in 50 noise-exposed men, aged 24-51 years (mean age, 35.5 years), using PTA, tympanometry and DPOAE. The control group consisted of 40 non-exposed persons with good hearing condition. RESULTS: Maximum levels of acoustic pressure exceeded Polish standards. Comparison between two groups showed that PTA was higher in the exposed persons by 6.3-6.8 dB on average and DPOAE was reduced in the group exposed to jet engine noise more than it could have been expected. CONCLUSIONS: Even during a single test, aircraft technical personnel was exposed to (audible) noise that significantly exceeded admissible values. The reduction in DPOAE values in persons exposed to noise of jet engines was incommensurably higher than changes in PTA.

Acoustic Impedance Tests↗
PubMed1990

Genetic engineering of the pseudorabies virus genome to construct live vaccines.

Pseudorabies virus (PRV) is a herpesvirus of pigs. Homologous recombination with plasmids offers a method to engineer precise changes in the PRV genome to produce advantageous live vaccines. Safety can be ensured by using a non-reverting deletion to inactivate the thymidine kinase gene. One particularly important feature of new PRV vaccines is deletion of an antigen, so that vaccinated pigs are serologically distinguishable from infected pigs. We have constructed a live vaccine strain with deletions in the thymidine kinase gene and in the gene for a glycoprotein, gX. Molecular engineering techniques made it possible to choose deletion of gX, which has no known immunological significance, over deletion of other glycoproteins that contribute to protective immunity. Extensive experiments in pigs with isogenic virus pairs show that deletion of gX does not compromise efficacy of a vaccine as gI deletions do. Deletion of gX also suggests a site for replacement with antigens from other pathogens. In addition to molecular engineering of a live vaccine strain, research on PRV glycoproteins has led to the discovery that expression of the glycoprotein gp50 makes cells resistant to PRV infection. Perhaps this observation could be extrapolated to the level of a whole animal to allow engineering of pigs to become an alternative to engineered vaccines.

Animals↗
PubMedDate not supplied

[Thermodynamic principles and physiologic criteria for the use of heat engines to drive the ventricles of an artificial heart].

The authors review the thermodynamic bases and physiological limitations of the applicability of thermal engines for driving artificial heart ventricles. Show that the thermodynamic characteristics of Stirling and Brighton cycles do not make it possible to effectively use cycle-based engines in the artificial heart. A steam engine operating in accordance with the Rankine cycle may be regarded as an optimum type engine for that purpose. Demonstrate that according to the rules of physiology, use should be made of a separate driving of artificial heart ventricles by two independently operating steam engines. Provide the characteristics of the Soviet artificial heart "MIKRON" acceptable for implantation into the orthotopic position.

Equipment Design↗
PubMed1989

[Inference engines of expert systems for designing removable partial dentures].

The expert system for designing removable partial dentures has a great potentiality for clinical and educational use. The system sorts out several solutions for clinical problems with the aid of logic and data bases stored in the memory bank. The most important part of this system is the inference engine. Production system and frame system are often used as the inference engine. The purpose of this report was to compare different types of inference engine in practical situations. Following conclusion were obtained. 1) Since each type of inference engine has its own advantages and disadvantages, one has to select most suitable one for the purpose of the system. 2) One must select the inference engine type which will help potential user's understanding.

Denture Design↗
PubMed1993

Evolution of hospital industrial engineering: from scientific management to total quality management.

Industrial engineering applications in the hospital industry first began in 1910. This paper traces the evolution of hospital industrial engineering in five distinct phases. For each of the major phases, this paper presents the contributions made by industrial engineers. Many of the techniques advocated by industrial engineers are now being taught to hospital employees as hospitals introduce total quality management (TQM) within the health-care industry. TQM introduction has meant a new role for industrial engineers, as that of a teacher, coach, and a facilitator. This new role holds much promise for the improvement of quality and productivity in health care.

Efficiency, Organizational↗
PubMed1996

Enhanced detection, maintenance, and differentiation of primitive human hematopoietic cells in cultures containing murine fibroblasts engineered to produce human steel factor, interleukin-3, and granulocyte colony-stimulating factor.

To determine whether the sensitivity of the human long-term culture-initiating cell (LTC-IC) assay could be increased, we have evaluated a spectrum of different fibroblast cell lines for their abilities to influence the number of cells detectable as LTC-IC, to influence LTC-IC maintenance, and/or to influence LTC-IC differentiation into colony-forming cells (CFC) in cocultures containing various sources of LTC-IC. In a series of initial experiments with highly purified subpopulations of CD34+ cells from normal human marrow, no significant difference could be found between any of 3 different murine stromal fibroblast cells in terms of their support of either LTC-IC detection (CFC production) or maintenance (over a 6-week period), and all were equivalent to primary human marrow feeders (HMF). On the other hand, murine M2-10B4 fibroblasts engineered to produce high levels of both human granulocyte colony-stimulating factor (G-CSF) and interleukin-3 (IL-3; 190 and 4 ng/mL, respectively), either alone or mixed 1:1 with SI/SI fibroblasts engineered to produce high levels of soluble Steel factor (SF), with or without production of the transmembrane form of SF (60 and 4 ng/ mL, respectively), stimulated the production of up to 20-fold more CFC in LTC of cells from normal human marrow, G-CSF-mobilized blood or cord blood when compared with parallel cocultures containing HMF. Limiting dilution analysis of the CFC output from all three sources of LTC-IC showed that most of this increase was due to an ability of the engineered feeders to increase the plating efficiency of the LTC-IC assay (approximately 14-fold for marrow LTC-IC and approximately 4-fold for cord blood or mobilized blood LTC-IC). Analysis of the phenotype of these additionally recruited LTC-IC from marrow showed they had the same primitive CD34+CD45RA-CD71- phenotype as conventionally defined LTC-IC. The limiting dilution studies also showed that the average number of CFC produced per LTC-IC was additionally and independently increased to yield values of 18 CFC per LTC-IC in marrow, 28 for LTC-IC in cord blood, and 25 for LTC-IC in G-CSF-mobilized blood. Replating of cells from primary LTC with different feeders into secondary LTC-IC assays containing the best combination of engineered feeders showed that LTC-IC maintenance could be significantly enhanced (up to 7-fold as compared with primary cocultures containing HMF). However, this enhancement was still not sufficient to amplify the number of LTC-IC present after 6 weeks above the input value. Thus, engineering murine fibroblasts to produce sufficient SF, G-CSF, and IL-3 can markedly enhance the detection as well as the maintenance in vitro of a very primitive population of human progenitor cells present in normal adult marrow, mobilized blood, and cord blood by providing the most sensitive assay conditions thus far described. The present findings also provide new evidence of biologic heterogeneity between different cell populations that can be operationally identified as LTC-IC, thus re-emphasizing the importance of limiting dilution analyses to distinguish between quantitative and qualitative effects on these cells.

Animals↗
PubMed1990

Clinical engineering in Italy: the activity of the National Research Council.

The results of a five-year effort to rationalise the process of acquisition and management of medical instrumentation in Italy are reported and discussed. The research programme, sponsored by the National Research Council of Italy, was completed in 1988 and focused on (1) acquisition of technology by hospitals; (2) assessment of performance evaluation and preventive maintenance procedures for biomedical equipment; (3) cost analysis of high-technology health services; (4) analysis of clinical engineering activities in Italy. The present situation and guidelines for the future are outlined. In Italy there are no official positions for clinical engineers in public hospitals; however seven health-delivery institutions have established some activity in the field and a total of 15 engineers are involved in it. Despite the obvious advantage shown by the experience of these pilot institutions, the field has serious difficulties in developing due to the policy of the Ministry of Health and the consequent lack of positions. To reach the level of service provided in other European or North American countries, Italy would need at least 500 clinical engineers and 2500 biomedical equipment technicians. However, the lack of professional opportunities does not encourage training activities in the field.

Biomedical Engineering↗
PubMed2004

Tissue engineering: current state and perspectives.

Tissue engineering is an interdisciplinary field that involves cell biology, materials science, reactor engineering, and clinical research with the goal of creating new tissues and organs. Significant advances in tissue engineering have been made through improving singular aspects within the overall approach, e.g., materials design, reactor design, or cell source. Increasingly, however, advances are being made by combining several areas to create environments which promote the development of new tissues whose properties more closely match their native counterparts. This approach does not seek to reproduce all the complexities involved in development, but rather seeks to promote an environment which permits the native capacity of cells to integrate, differentiate, and develop new tissues. Progenitors and stem cells will play a critical role in understanding and developing new engineered tissues as part of this approach.

Animals↗
PubMed2001

Metabolic engineering.

Metabolic engineering has developed as a very powerful approach to optimising industrial fermentation processes through the introduction of directed genetic changes using recombinant DNA technology. Successful metabolic engineering starts with a careful analysis of cellular function; based on the results of this analysis, an improved strain is designed and subsequently constructed by genetic engineering. In recent years some very powerful tools have been developed, both for analysing cellular function and for introducing directed genetic changes. In this paper, some of these tools are reviewed and many examples of metabolic engineering are presented to illustrate the power of the technology. The examples are categorised according to the approach taken or the aim: (1) heterologous protein production, (2) extension of substrate range, (3) pathways leading to new products, (4) pathways for degradation of xenobiotics, (5) improvement of overall cellular physiology, (6) elimination or reduction of by-product formation, and (7) improvement of yield or productivity.

Biotechnology↗
PubMed2026

Unlocking the molecular engineering of Geobacillus glycoside hydrolases as a source of industrial biocatalysts.

This review examines Geobacillus sensu stricto as a source of thermostable glycoside hydrolases (GH) for biomass conversion, food processing, and enzyme engineering. Recent peer-reviewed literature was assessed with emphasis on taxonomy, genome-based Carbohydrate-Active Enzymes (CAZyme) prediction, biochemical validation, structural data, and engineering case studies. Taxonomic boundaries were interpreted using current Anoxybacillaceae frameworks, with Parageobacillus treated as a related comparator rather than as Geobacillus. The strongest evidence supports GH13 alpha-amylases, xylan-active systems, beta-xylosidases, and selected accessory enzymes. Recent studies also show that genome mining must be coupled with enzymatic assays and product profiling because CAZyme annotation alone does not prove industrial function. Molecular engineering has improved relevant traits, including the longer thermal half-life of engineered G. stearothermophilus alpha-amylase variants, the increased catalytic efficiency of oligo-alpha-1,6-glucosidase variants, and improved AmyS expression in Bacillus subtilis. Geobacillus glycoside hydrolases are best interpreted as process-specific, engineerable biocatalytic templates. Their translation requires reliable taxonomy, functional validation, structural interpretation, scalable expression and testing on realistic substrates. This synthesis also recognises current limitations: many predicted CAZymes still lack biochemical validation, complete cellulolytic systems remain less mature than xylan- and starch-active systems, and scale-up data remain scarce.

Geobacillus↗
PubMed2025

Combinatorial genome engineering of pseudorabies virus Bartha by developing a reverse genetic system based on three overlapping genomic segments.

INTRODUCTION: The 138-kilobase genome of pseudorabies virus vaccine strain Bartha K61 harbors many nonessential genes for replication and exhibits remarkable capacity for incorporating foreign genes for therapeutic applications. However, the large size of the Bartha genome complicates its efficient engineering. OBJECTIVES: Development of a reverse genetic system for pseudorabies virus Bartha based on three overlapping genomic segments to facilitate multiplex genome engineering. METHODS: The 138-kb genome of Bartha was split into three overlapping segments (42 kb, 43 kb, and 53 kb), each cloned in a bacterial artificial chromosome (BAC) to facilitate genome engineering. The infectious virus was reconstituted by transfecting the 3 genomic fragments released from the BACs into Vero cells in which a complete virus genome was assembled using 2-kb overlaps between adjacent pieces. RESULTS: Employing the reverse genetic system, we individually deleted 15 candidate nonessential genes and confirmed that 10 were dispensable for viral growth in cell culture. Deletion of 7 nonessential genes had no impact on viral growth, whereas UL47 deletion reduced viral growth rate and deletions of UL44, UL47, or US3 resulted in smaller viral plaques. A total of 45 viral genomes with double deletions of nonessential genes were constructed, among which 22 were successfully rescued into infectious virions. Fifteen double-deletion mutant viruses had a viral titer comparable with the wild-type Bartha, while the remaining 7 showed a lower titer. Additionally, expressions of the mNeonGreen reporter gene at nonessential gene loci were evaluated. Cells infected with recombinant viruses carrying mNeonGreen at 8 loci showed strong green fluorescence, whereas those with mNeonGreen at 2 loci exhibited very weak fluorescence. CONCLUSION: The reverse genetic system developed in this study enables rapid and combinatorial engineering of viruses with the large DNA genome, and will accelerate development of large DNA virus-based therapeutics including live-attenuated vaccines, vector vaccines, and oncolytic herpesviruses.

Herpesvirus 1, Suid↗
PubMed2005

[Cartilage tissue engineering: state-of-the-art and future approaches].

Lesions of the articular cartilage have a large variety of causes among which traumatic damage, osteoarthritis and osteochondritis dissecans are the most frequent. Returning damaged cartilage in articular joints back to a functionally normal state has been a major challenge for orthopaedic surgeons. This interest results in large part because cartilage defects cannot adequately heal themselves. Current techniques used in orthopaedic practice to repair cartilage give variable and unpredictable results. Bone marrow stimulation techniques such as abrasion arthroplasty, drilling and microfracture produce mostly fibrocartilage. Autologous osteochondral transplant systems (mosaicplasty) have shown encouraging results. Autologous chondrocyte transplantation has led to a hyaline articular cartilage repair but little is known about the predictability and reliability of the procedure. The rapidly emerging field of tissue engineering promises creation of viable substitutes for failing cartilage tissue. Current tissue engineering approaches are mainly focused on the restoration of pathologically altered tissue structure based on the transplantation of cells in combination with supportive matrices and molecules. Among natural and synthetic matrices, collagen and polysaccharidic biomaterials have been extensively used with promising results. Recently, interest has switched to the use of mesenchymal stem cells instead of chondrocytes. Tissue engineering offers the possibility to treat localised cartilage lesions. Genetic engineering techniques using genetically modified chondrocytes offer also the opportunity to treat diffuse cartilage lesions occurring in osteoarthritis or inflammatory joint diseases. Electroporation is specially a reliable and inexpensive technique that shares with electrochemotherapy an ability to target the chondrocytes despite the barrier effect of the extracellular matrix without viral vectors. The authors review recent research achievements and highlight the potential clinical applications of new technologies in the treatment of patients with cartilage injuries.

Animals↗
PubMed2026

In vivo immune cell engineering from bench to clinical reality.

Adoptive immune cell therapies, exemplified by chimeric antigen receptor T cells, have transformed the treatment of hematological malignancies. However, their broader clinical application is limited by complex ex vivo manufacturing, high cost, and safety concerns. In vivo immune cell engineering has emerged as an alternative strategy that delivers genetic instructions directly to immune cells, thereby generating or modulating therapeutic immune cells within the body and reducing the reliance on individualized in vitro operations. These advances underscore the need for a systematic evaluation of this emerging field. Therefore, this review systematically summarizes the mechanistic principles and delivery strategies underlying in vivo immune cell engineering, with an emphasis on in vivo CAR-T cell generation and the engineering of other immune cells. We then discuss major viral and non-viral delivery platforms and clarify how these platforms influence cargo delivery, cell specificity, and functional immune-cell programming. We further discuss recent preclinical and emerging clinical advances across cancer, autoimmune diseases, and degenerative diseases, while examining key translational challenges, including delivery specificity, off-target effects, controllability, persistence, and manufacturing standardization. Overall, although the field of in vivo immune cell engineering is advancing rapidly, its clinical success will depend on coordinated improvements in delivery precision, therapeutic efficacy, safety, and controllable immune-cell programming.

Cancer immunotherapy↗
PubMed2004

Therapeutic cloning and tissue engineering.

A severe shortage of donor organs available for transplantation in the United States leaves patients suffering from diseased and injured organs with few treatment options. Scientists in the field of tissue engineering apply the principles of cell transplantation, material science, and engineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for tissue engineering applications. The present chapter reviews recent advances that have occurred in therapeutic cloning and tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.

Animals↗