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  • 1
    ISSN: 0006-3592
    Keywords: baculovirus ; BTI-TN5B1-4 ; single-cell ; suspension ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sulfated polyanions have been successfully used to rapidly obtain and maintain stable single-cell suspension of BTI-TN5B1-4 cells, a cell line which has a high intrinsic capacity for recombinant protein production but clumps severely in suspension reducing its effectiveness as a host for foreign protein production with the baculovirus expression vector system. The efficacy of inducing single-cell suspension correlated positively with the increase in sulfation of the added polyanion. Unsulfated polyanions, neutral polymers, polycations, disaccharides, and monosaccharides were ineffective in inducing single-cell suspension.Elimination of clumping in suspension culture by adding a dispersing agent can lead to enhanced recombinant protein production. Inducing single-cell suspension with dextran sulfate, a highly sulfated polyanion, resulted in a four-fold increase in volumetric yield of the recombinant glycosylated protein, human secreted alkaline phosphatase, and a two-fold increase in volumetric yield of the recombinant cytoplasmic protein, β-galactosidase. High yields of 82 U/ml (ca. 110 mg/L) for alkaline phosphatase, and 705 U/mL (ca. 2.3 g/L) for β-galactosidase under elevated oxygen have been obtained. The optimum volumetric yield of alkaline phosphatase in BTI-TN5B1-4 dextran sulfate cells under elevated oxygen but unsupplemented medium is 6 to 11-fold higher than attached cultures, and 3-fold higher than the best yield obtained for SF21 cells in suspension at elevated oxygen and with nutrient supplementation. More importantly, cells can be infected at high density without complications from aggregation, which has important implications for scale-up. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54:191-205, 1997.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 206-220 
    ISSN: 0006-3592
    Keywords: baculovirus ; BTI-TN5B1-4 ; infection ; attachment ; polyanions ; model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sulfated polyanions can be used to rapidly induce and maintain single-cell suspensions of BTI-TN5B1-4 insect cells, a cell line which clumps in suspension. Elimination of cell clumping results in a significant increase in volumetric yield of the baculovirus expression vector system. Sulfated polyanions, however, inhibited baculovirus infection of BTI-TN5B1-4. Data from binding studies and fusion assays suggest that the inhibition of infection was not due to the observed reduction in viral attachment rate but to inhibition of viral membrane fusion in the endosome.The three most effective polyanions for inducing single cells are dextran sulfate, pentosan sulfate, and polyvinyl sulfate. At concentrations required for single-cell formation, dextran sulfate and pentosan sulfate did not affect viral infection at multiplicities of infection greater than one plaque forming unit per cell. In contrast, polyvinyl sulfate blocked viral infection even at a high multiplicity of infection of 20 plaque-forming units per cell. To bypass this inhibition, polyvinyl sulfate can be removed by resuspending the cells in fresh medium before virus addition, and then added back to the cell suspension after a substantial amount of virus has been internalized. Alternatively, polyvinyl sulfate can be neutralized with a polycation before virus addition, and an equivalent amount of polyvinyl sulfate added back after most of the virus has been internalized. We present a simple mathematical model of the attachment and entry of baculovirus in BTI-TN5B1-4, which can be used to design appropriate infection regimens. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 206-220, 1997.
    Additional Material: 12 Ill.
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  • 3
    Publication Date: 2013-08-31
    Description: A prototype twin-camera stereo vision system for autonomous robots has been developed at Goddard Space Flight Center. Standard charge coupled device (CCD) imagers are interfaced with commercial frame buffers and direct memory access to a computer. The overlapping portions of the images are analyzed using photogrammetric techniques to obtain information about the position and orientation of objects in the scene. The camera head consists of two 510 x 492 x 8-bit CCD cameras mounted on individually adjustable mounts. The 16 mm efl lenses are designed for minimum geometric distortion. The cameras can be rotated in the pitch, roll, and yaw (pan angle) directions with respect to their optical axes. Calibration routines have been developed which automatically determine the lens focal lengths and pan angle between the two cameras. The calibration utilizes observations of a calibration structure with known geometry. Test results show the precision attainable is plus or minus 0.8 mm in range at 2 m distance using a camera separation of 171 mm. To demonstrate a task needed on Space Station Freedom, a target structure with a movable I beam was built. The camera head can autonomously direct actuators to dock the I-beam to another one so that they could be bolted together.
    Keywords: CYBERNETICS
    Type: NASA, Ames Research Center, Vision Science and Technology at NASA: Results of a Workshop; p 55
    Format: application/pdf
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