Página 18 dos resultados de 1523 itens digitais encontrados em 0.001 segundos

‣ Bioengineering and Imaging Research Opportunities Workshop V: Summary of Findings on Imaging and Characterizing Structure and Function in Native and Engineered Tissues

Hendee, William R.; Cleary, Kevin; Ehman, Richard L.; Fullerton, Gary D.; Grundfest, Warren S.; Haller, John; Kelley, Christine A.; Meyer, Anne E.; Murphy, Robert F.; Phillips, William; Torchilin, Vladimir P.
Fonte: Radiological Society of North America Publicador: Radiological Society of North America
Tipo: Artigo de Revista Científica
Publicado em /08/2008 Português
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‣ Evaluation of Kinematics of Anterior Cruciate Ligament-Deficient Knees with Use of Advanced Imaging Techniques, Three-Dimensional Modeling Techniques, and Robotics

Van de Velde, Samuel K.; Gill, Thomas J.; Li, Guoan
Fonte: Journal of Bone and Joint Surgery, Inc Publicador: Journal of Bone and Joint Surgery, Inc
Tipo: Artigo de Revista Científica
Publicado em 01/02/2009 Português
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Measuring knee biomechanics in six degrees of freedom with acceptable accuracy has been proven to be technically challenging. At our bioengineering laboratory, we have employed both an in vitro robotic testing system and an in vivo combined dual fluoroscopic and magnetic resonance imaging technique to analyze the impact of anterior cruciate ligament rupture on the knee joint.

‣ FieldML: concepts and implementation

Christie, G. Richard; Nielsen, Poul M.F.; Blackett, Shane A.; Bradley, Chris P.; Hunter, Peter J.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 28/05/2009 Português
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The field modelling language FieldML is being developed as a standard for modelling and interchanging field descriptions in software, suitable for a wide range of computation techniques. It comprises a rich set of operators for defining generalized fields as functions of other fields, starting with basic domain fields including sets of discrete objects and coordinate systems. It is extensible by adding new operators and by their arbitrary combination in expressions, making it well suited for describing the inherent complexity of biological materials and organ systems. This paper describes the concepts behind FieldML, including a simple example of a spatially varying finite-element field. It outlines current implementations in established, open source computation and visualization software, both drawing on decades of bioengineering modelling software development experience.

‣ Bioconjugated nanoparticle detection of respiratory syncytial virus infection

Tripp, Ralph A; Alvarez, Rene; Anderson, Blake; Jones, Les; Weeks, Craig; Chen, Wei
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
Português
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The integration of nanotechnology with biology has produced major advances in molecular diagnostics, therapeutics, and bioengineering. Recent advances have led to the development of functionalized nanoparticles (NPs) that are covalently linked to biological molecules such as antibodies, peptides, proteins, and nucleic acids. These functionalized NPs allow for development of novel diagnostic tools and methods, particularly for pathogens, as rapid and sensitive diagnostics are essential for defining the emergence of infection, determining the period that preventive measures should be applied, for evaluating drug and vaccine efficacy, and for controlling epidemics. In this study, we show that functionalized NPs conjugated to monoclonal antibodies can be used to rapidly and specifically detect respiratory syncytial virus in vitro and in vivo. These results suggest that functionalized NPs can provide direct, rapid, and sensitive detection of viruses and thereby bridge the gap between current cumbersome virus detection assays and the burgeoning need for more rapid and sensitive detection of viral agents.

‣ Single-Chain Insulins as Receptor Agonists

Rajpal, Gautam; Liu, Ming; Zhang, Yi; Arvan, Peter
Fonte: The Endocrine Society Publicador: The Endocrine Society
Tipo: Artigo de Revista Científica
Português
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Single-chain insulins (SCIs) are single polypeptide chains in which the insulin B-chain links contiguously with the insulin A-chain via an uncleaved connecting peptide. Although direct linkage of insulin B- and A-chains produces SCIs with little insulin receptor binding, biologists have been interested in bioengineering linker peptides that form a flexible reverse turn, allowing SCIs to activate insulin receptors. In this report, we have investigated a series of cDNAs intended to explore the significance of linker length, cleavability, and the impact of certain site-dependent residues for the bioactivity of recombinant SCIs on insulin receptors. SCI concentration is readily measured by RIA with a (proinsulin plus insulin)-specific polyclonal antibody. Although dibasic flanking residues may result in potential endoproteolytic susceptibility, a linker with -Gln-Arg- flanking sequences resisted cleavage even in secretory granules, ensuring single-chain behavior. Effective SCIs exhibit favorable and specific binding with insulin receptors. SCIs with linkers bearing an Arg residue immediately preceding the A-chain were most bioactive, although efficient receptor interaction was inhibited as SCI linker length increased, approaching that observed for proinsulin. SCIs activate downstream metabolic signaling...

‣ Bioengineering to Enhance Progenitor Cell Therapeutics

Tongers, Jörn; Webber, Matthew J.; Losordo, Douglas W.
Fonte: Texas Heart Institute Publicador: Texas Heart Institute
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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‣ Quantitative Evaluation of His-Tag Purification and Immunoprecipitation of Tristetraprolin and Its Mutant Proteins from Transfected Human Cells

Cao, Heping; Lin, Rui
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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Histidine (His)-tag is widely used for affinity purification of recombinant proteins, but the yield and purity of expressed proteins are quite different. Little information is available about quantitative evaluation of this procedure. The objective of current study was to evaluate His-tag procedure quantitatively and to compare it with immunoprecipitation using radiolabeled tristetraprolin (TTP), a zinc finger protein with anti-inflammatory property. Human embryonic kidney 293 cells were transfected with wild-type and nine mutant plasmids with single or multiple phosphorylation site mutation(s) in His-TTP. These proteins were expressed and mainly localized in the cytosol of transfected cells by immunocytochemistry and confocal microscopy. His-TTP proteins were purified by Ni-NTA beads with imidazole elution or precipitated by TTP antibodies from transfected cells after being labeled with [32P]-orthophosphate. The results showed that 1) His-tag purification was more effective than immunoprecipitation for TTP purification; 2) mutations in TTP increased the yield of His-TTP by both purification procedures; and 3) mutations in TTP increased the binding affinity of mutant proteins for Ni-NTA beads. These findings suggest that bioengineering phosphorylation sites in proteins can increase the production of recombinant proteins.

‣ Silk-Based Electrospun Tubular Scaffolds for Tissue-Engineered Vascular Grafts

Soffer, Leah; Wang, Xianyan; Zhang, Xiaohui; Kluge, Jonathan; Dorfmann, Luis; Kaplan, David L.; Leisk, Gary
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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Electrospinning was used to fabricate nonwoven nanofibrous tubular structures from Bombyx mori silk fibroin using an all aqueous process. The tubes were prepared for cell studies related to the bioengineering of small diameter vascular grafts. Prior to cell culture, the structures displayed a burst strength of 811±77.2 mmHg, sufficient to withstand arterial pressures. The tensile properties were similar to native vessels, with an ultimate tensile strength of 2.42± 0.48 MPa and a linear modulus of 2.45±0.47 MPa. Human endothelial cells and smooth muscle cells were successfully cultured on the electrospun silk, demonstrating the potential utility of these scaffolds for vascular grafts due to the combination of impressive mechanical properties and biological compatibility.

‣ Medical Biofilms

Bryers, James D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/05/2008 Português
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For more than two decades, Biotechnology and Bioengineering has documented research focused on natural and engineered microbial biofilms within aquatic and subterranean ecosystems, wastewater and waste-gas treatment systems, marine vessels and structures, and industrial bioprocesses. Compared to suspended culture systems, intentionally engineered biofilms are heterogeneous reaction systems that can increase reactor productivity, system stability, and provide inherent cell: product separation. Unwanted biofilms can create enormous increases in fluid frictional resistances, unacceptable reductions in heat transfer efficiency, product contamination, enhanced material deterioration, and accelerated corrosion. Missing from B&B has been an equivalent research dialogue regarding the basic molecular microbiology, immunology, and biotechnological aspects of medical biofilms. Presented here are the current problems related to medical biofilms; current concepts of biofilm formation, persistence, and interactions with the host immune system; and emerging technologies for controlling medical biofilms.

‣ Acute Stroke Imaging Research Roadmap

Wintermark, Max; Albers, Gregory W.; Alexandrov, Andrei V.; Alger, Jeffry R.; Bammer, Roland; Baron, Jean-Claude; Davis, Stephen; Demaerschalk, Bart M.; Derdeyn, Colin P.; Donnan, Geoffrey A.; Eastwood, James D.; Fiebach, Jochen B.; Fisher, Marc; Furie, K
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/2008 Português
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The recent “Advanced Neuroimaging for Acute Stroke Treatment” meeting on September 7 and 8, 2007 in Washington DC, brought together stroke neurologists, neuroradiologists, emergency physicians, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke (NINDS), the National Institute of Biomedical Imaging and Bioengineering (NIBIB), industry representatives, and members of the US Food and Drug Administration (FDA) to discuss the role of advanced neuroimaging in acute stroke treatment. The goals of the meeting were to assess state-of-the-art practice in terms of acute stroke imaging research and to propose specific recommendations regarding: (1) the standardization of perfusion and penumbral imaging techniques, (2) the validation of the accuracy and clinical utility of imaging markers of the ischemic penumbra, (3) the validation of imaging biomarkers relevant to clinical outcomes, and (4) the creation of a central repository to achieve these goals. The present article summarizes these recommendations and examines practical steps to achieve them.

‣ Meningomylocele: An update

Kapoor, R.; Agrawal, S.
Fonte: Medknow Publications Publicador: Medknow Publications
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
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Therapy-resistant overactivity of detrusor or small capacity and poor compliance, will usually need to be treated by bladder augmentation. Ileal or colonic patches are used frequently for augmenting the bladder, with either intestinal segment appearing to be equally useful. Stomach is rarely used because of the associated complications, but it is the only available intestinal segment for patients with impaired renal function. Concerns regarding long-term effects of associated metabolic acidosis, including abnormalities in linear growth and bone metabolism are misplaced. Ureterocystoplasty offers an attractive urothelium-preserving alternative, avoiding the metabolic complications, mucus production and cancer risk of heterotopic epithelium associated with enterocystoplasty. Though ideal for patients with dilated ureter and nonfunctioning kidney, in patients with functioning kidney it carries added risks associated with transuretero-ureterostomy, mainly obstruction. Ureteral dilatation in meningomyelocele patients is avoidable with proper follow-up and treatment. Therefore they rarely should be candidates for this operation. Alternative urothelium-preserving techniques, such as auto augmentation and seromuscular cystoplasty, have not proven to be as successful as standard augmentation with intestinal segment. Work is in progress on various bioengineering techniques to culture and combine bladder cells in tissue culture for regeneration. Early efforts are exciting...

‣ Mechanosensitivity of fibroblast cell shape and movement to anisotropic substratum topography gradients

Kim, Deok-Ho; Han, Karam; Gupta, Kshitiz; Kwon, Keon Woo; Suh, Kahp-Yang; Levchenko, Andre
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/2009 Português
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In this report, we describe using ultraviolet (UV)-assisted capillary force lithography (CFL) to create a model substratum of anisotropic micro- and nanotopographic pattern arrays with variable local density for the analysis of cell-substratum interactions. A single cell adhesion substratum with the constant ridge width (1 µm), and depth (400 nm) and variable groove widths (1 µm to 9.1 µm) allowed us to characterize the dependence of cellular responses, including cell shape, orientation, and migration, on the anisotropy and local density of the variable micro- and nanotopographic pattern. We found that fibroblasts adhering to the denser pattern areas aligned and elongated more strongly along the direction of ridges, vs. those on the sparser areas, exhibiting a biphasic dependence of the migration speed on the pattern density. In addition, cells responded to local variations in topography by altering morphology and migrating along the direction of grooves biased by the direction of pattern orientation (short term) and pattern density (long term). Molecular dynamic live cell imaging and immunocytochemical analysis of focal adhesions and actin cytoskeleton suggest that variable substratum topography can result in distinct types of cytoskeleton reorganization. We also demonstrate that fibroblasts cultured as monolayers on the same substratum retain most of the properties displayed by single cells. This result...

‣ The role of predictive modelling in rationally re-engineering biological systems

Koide, Tie; Pang, Wyming Lee; Baliga, Nitin S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
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Technologies to synthesize and transplant a complete genome into a cell have opened limitless potential to redesign organisms for complex, specialized tasks. However, large-scale re-engineering of a biological circuit will require systems-level optimization that will come from a deep understanding of operational relationships among all the constituent parts of a cell. The integrated framework necessary for conducting such complex bioengineering requires the convergence of systems and synthetic biology. Here, we review the status of these rapidly developing interdisciplinary fields of biology and provide a perspective on plausible venues for their merger.

‣ Prevascularization of cardiac patch on the omentum improves its therapeutic outcome

Dvir, Tal; Kedem, Alon; Ruvinov, Emil; Levy, Oren; Freeman, Inbar; Landa, Natalie; Holbova, Radka; Feinberg, Micha S.; Dror, Shani; Etzion, Yoram; Leor, Jonathan; Cohen, Smadar
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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The recent progress made in the bioengineering of cardiac patches offers a new therapeutic modality for regenerating the myocardium after myocardial infarction (MI). We present here a strategy for the engineering of a cardiac patch with mature vasculature by heterotopic transplantation onto the omentum. The patch was constructed by seeding neonatal cardiac cells with a mixture of prosurvival and angiogenic factors into an alginate scaffold capable of factor binding and sustained release. After 48 h in culture, the patch was vascularized for 7 days on the omentum, then explanted and transplanted onto infarcted rat hearts, 7 days after MI induction. When evaluated 28 days later, the vascularized cardiac patch showed structural and electrical integration into host myocardium. Moreover, the vascularized patch induced thicker scars, prevented further dilatation of the chamber and ventricular dysfunction. Thus, our study provides evidence that grafting prevascularized cardiac patch into infarct can improve cardiac function after MI.

‣ Isolation of a Variant of Subtilosin A with Hemolytic Activity▿

Huang, Tai; Geng, Hao; Miyyapuram, Venugopal R.; Sit, Clarissa S.; Vederas, John C.; Nakano, Michiko M.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
Português
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Bacillus subtilis produces an anionic bacteriocin called subtilosin A that possesses antibacterial activity against certain gram-positive bacteria. In this study, we uncovered a hemolytic mutant of B. subtilis that produces an altered form of subtilosin A. The mutant bacteriocin, named subtilosin A1, has a replacement of threonine at position 6 with isoleucine. In addition to the hemolytic activity, subtilosin A1 was found to exhibit enhanced antimicrobial activity against specific bacterial strains. The B. subtilis albB mutant that does not produce a putative immunity peptide was more sensitive to both subtilosin A and subtilosin A1. A spontaneous suppressor mutation of albB that restored resistance to subtilosin A and subtilosin A1 was obtained. The sbr (subtilosin resistance) mutation conferring the resistance is not linked to the sboA-alb locus. The sbr mutation does not increase the resistance of B. subtilis to other cell envelope-targeted antimicrobial agents, indicating that the mutation specifically confers the resistance to subtilosins. The findings suggest possible bioengineering approaches for obtaining anionic bacteriocins with enhanced and/or altered bactericidal activity. Furthermore, future identification of the subtilosin-resistant mutation could provide insights into the mechanism of subtilosin A activity.

‣ “Opening” The Mesenchymal Stem Cell Tool Box

Zeidán-Chuliá, Fares; Noda, Mami
Fonte: Dental Investigations Society Publicador: Dental Investigations Society
Tipo: Artigo de Revista Científica
Publicado em /07/2009 Português
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Adult mesenchymal stem cells (MSCs) are adherent stromal cells able to self-renew and differentiate into a wide variety of cells and tissues. MSCs can be obtained from distinct tissue sources and have turned out to be successfully manipulated in vitro. As adult stem cells, MSCs are less tumorigenic than their embryonic correlatives and posses another unique characteristic which is their almost null immunogenicity. Moreover, these cells seem to be immunosuppressive in vitro. These facts together with others became MSCs a promising subject of study for future approaches in bioengineering and cell-based therapy. On the other hand, new strategies to achieve long-term integration as well as efficient differentiation of these cells at the area of the lesion are still challenging, and the signalling pathways ruling these processes are not completely well characterized. In this review, we are going summarize the general landscape and current status of the MSC tool as well as their wide potential in tissue engineering, from neuronal to tooth replacement. Highlights and pitfalls for further clinical applications will be discussed.

‣ A Tribute to Professor Van C. Mow: A Wonderful Scholar and Leader in Bioengineering

Chien, Shu
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Português
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‣ Neural Crest Lineage Segregation: a Blueprint for Periodontal Regeneration

Luan, X.; Dangaria, S.; Ito, Y.; Walker, C.G.; Jin, T.; Schmidt, M.K.; Galang, M.T.; Druzinsky, R.
Fonte: SAGE Publications Publicador: SAGE Publications
Tipo: Artigo de Revista Científica
Publicado em /09/2009 Português
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During the recent decade, the periodontal attachment apparatus has become one of the premier areas of the body for the development of novel tissue-engineering strategies. In the present review, we describe a developmental biology approach to characterize current concepts in periodontal regeneration and to discuss strategies for future applications in periodontal therapies. To decipher the developmental make-up of the periodontal region, we have followed the path of the migratory neural crest, since it gives rise to periodontal progenitor tissues, which in turn are subjected to the influence of diverse craniofacial extracellular matrices and peptide growth factors. Based on this developmental perspective, we have conducted a systematic analysis of the factors, progenitor cells, and matrices used in current periodontal tissue-engineering approaches. We propose that the developmental history of a tissue is a highly instructive design template for the discovery of novel bioengineering tools and approaches.

‣ Synthetic organisms and living machines: Positioning the products of synthetic biology at the borderline between living and non-living matter

Deplazes, Anna; Huppenbauer, Markus
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
Português
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The difference between a non-living machine such as a vacuum cleaner and a living organism as a lion seems to be obvious. The two types of entities differ in their material consistence, their origin, their development and their purpose. This apparently clear-cut borderline has previously been challenged by fictitious ideas of “artificial organism” and “living machines” as well as by progress in technology and breeding. The emergence of novel technologies such as artificial life, nanobiotechnology and synthetic biology are definitely blurring the boundary between our understanding of living and non-living matter. This essay discusses where, at the borderline between living and non-living matter, we can position the future products of synthetic biology that belong to the two hybrid entities “synthetic organisms” and “living machines” and how the approaching realization of such hybrid entities affects our understanding of organisms and machines. For this purpose we focus on the description of three different types of synthetic biology products and the aims assigned to their realization: (1) synthetic minimal cells aimed at by protocell synthetic biology, (2) chassis organisms strived for by synthetic genomics and (3) genetically engineered machines produced by bioengineering. We argue that in the case of synthetic biology the purpose is more decisive for the categorization of a product as an organism or a machine than its origin and development. This has certain ethical implications because the definition of an entity as machine seems to allow bypassing the discussion about the assignment and evaluation of instrumental and intrinsic values...

‣ Novel Internal Regions of Fluorescent Proteins Undergo Divergent Evolutionary Patterns

Gruber, David F.; DeSalle, Rob; Lienau, E. Kurt; Tchernov, Dan; Pieribone, Vincent A.; Kao, Hung-Teh
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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Over the past decade, fluorescent proteins (FPs) have become ubiquitous tools in biological research. Yet, little is known about the natural function or evolution of this superfamily of proteins that originate from marine organisms. Using molecular phylogenetic analyses of 102 naturally occurring cyan fluorescent proteins, green fluorescent proteins, red fluorescent proteins, as well as the nonfluorescent (purple-blue) protein sequences (including new FPs from Lizard Island, Australia) derived from organisms with known geographic origin, we show that FPs consist of two distinct and novel regions that have evolved under opposite and sharply divergent evolutionary pressures. A central region is highly conserved, and although it contains the residues that form the chromophore, its evolution does not track with fluorescent color and evolves independently from the rest of the protein. By contrast, the regions enclosing this central region are under strong positive selection pressure to vary its sequence and yet segregate well with fluorescence color emission. We did not find a significant correlation between geographic location of the organism from which the FP was isolated and molecular evolution of the protein. These results define for the first time two distinct regions based on evolution for this highly compact protein. The findings have implications for more sophisticated bioengineering of this molecule as well as studies directed toward understanding the natural function of FPs.