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Robust Process (robust + process)
Selected AbstractsCross-priming of CD8+ T,cells by viral and tumor antigens is a robust phenomenonEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2004Weisan Chen Abstract "Cross-priming" refers to the activation of naive CD8+ T,cells by antigen-presenting cells that have acquired nominal antigens from another cell. The biological relevance of cross-priming of CD8+ T,cells has recently been challenged (Zinkernagel, R. M., Eur. J. Immunol. 2002. 32: 2385,2392), on the basis that responses are weak or poorly quantitated, and the determinants recognized are undefined. Here we show that cross-priming is a robust process that elicits vigorous primary responses to multiple peptides in two well-defined systems. Our findings support the relevance of cross-priming in CD8+ T,cell responses to viruses and tumor cells, and demonstrate that cross-priming elicits CD8+ T,cells to determinants generated by the endogenous processing pathway. [source] Appointments to boards and committees via lottery, a pathway to fairness and diversityJOURNAL OF PUBLIC AFFAIRS, Issue 2 2009Lyn Carson Public appointments for committees or boards can be controversial due to cronyism or pandering to demands of noisy or powerful interest groups. One relatively unexplored method for selecting committee or board members is random selection which has advantages beyond interrupting cronyism. This paper canvasses the strengths and weaknesses of an unusual selection method and makes a case for the use of a lottery as a robust process that will lend legitimacy and credibility to committee or board governance. Copyright © 2009 John Wiley & Sons, Ltd. [source] pH measurement and a rational and practical pH control strategy for high throughput cell culture systemBIOTECHNOLOGY PROGRESS, Issue 3 2010Haiying Zhou Abstract The number of therapeutic proteins produced by cell culture in the pharmaceutical industry continues to increase. During the early stages of manufacturing process development, hundreds of clones and various cell culture conditions are evaluated to develop a robust process to identify and select cell lines with high productivity. It is highly desirable to establish a high throughput system to accelerate process development and reduce cost. Multiwell plates and shake flasks are widely used in the industry as the scale down model for large-scale bioreactors. However, one of the limitations of these two systems is the inability to measure and control pH in a high throughput manner. As pH is an important process parameter for cell culture, this could limit the applications of these scale down model vessels. An economical, rapid, and robust pH measurement method was developed at Eli Lilly and Company by employing SNARF-4F 5-(-and 6)-carboxylic acid. The method demonstrated the ability to measure the pH values of cell culture samples in a high throughput manner. Based upon the chemical equilibrium of CO2, HCO, and the buffer system, i.e., HEPES, we established a mathematical model to regulate pH in multiwell plates and shake flasks. The model calculates the required %CO2 from the incubator and the amount of sodium bicarbonate to be added to adjust pH to a preset value. The model was validated by experimental data, and pH was accurately regulated by this method. The feasibility of studying the pH effect on cell culture in 96-well plates and shake flasks was also demonstrated in this study. This work shed light on mini-bioreactor scale down model construction and paved the way for cell culture process development to improve productivity or product quality using high throughput systems. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Windows of operation for bioreactor design for the controlled formation of tissue-engineered arteriesBIOTECHNOLOGY PROGRESS, Issue 3 2009Spyridon Gerontas Abstract The availability of large numbers of units of artificial arteries would offer significant benefits to the clinical management of bypass surgery. Tissue engineering offers the potential of providing vessels that can mimic the morphology, function, and physiological environment of native vessels. Ideally this would involve culturing stem cells in vitro within a biodegradable tubular scaffold so as to construct tissue for implantation. Essential to establishing a robust process for the production of tissue-engineered arteries is the understanding of the impact of changes in the operating conditions and bioreactor design on the construct formation. In this article, models of transport phenomena were developed to predict the critical flow rates and mass transfer requirements of a prototype bioreactor for the formation of tissue-engineered arteries. The impact of the cell concentration, tube geometry, oxygen effective diffusivity in alginate, substrate and metabolite concentration levels, feed rate, and recycle rate on the design of the bioreactor was visualized using windows of operation and contour plots. The result of this analysis determined the best configuration of the bioreactor that meets the cellular transport requirements as well as being reliable in performance while seeking to reduce the amount of nutrients to be used. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Evaluation of Production Parameters with the Vaccinia Virus Expression System Using Microcarrier Attached HeLa CellsBIOTECHNOLOGY PROGRESS, Issue 2 2005Nicole A. Bleckwenn Parameters that affect production of the recombinant reporter protein, EGFP, in the T7 promoter based VOTE vaccinia virus-HeLa cell expression system were examined. Length of infection phase, inducer concentration, and timing of its addition relative to infection were evaluated in 6-well plate monolayer cultures. One hour infection with 1.0 mM IPTG added at the time of infection provided a robust process. For larger scale experiments, anchorage-dependent HeLa cells were grown on 5 g/L Cytodex 3 microcarriers. The change to this dynamic culture environment, with cell-covered microcarriers suspended in culture medium in spinner flasks, suggested a re-examination of the multiplicity of infection (MOI) for this culture type that indicated a need for an increase in the number of virus particles per cell to 5.0, higher than that needed for complete infection in monolayer tissue flask culture. Additionally, dissolved oxygen level and temperature during the protein production phase were evaluated for their effect on EGFP expression in microcarrier spinner flask culture. Both increased dissolved oxygen, based on surface area to volume (SA/V) adjustments, and decreased temperature from 37 to 31 °C showed increases in EGFP production over the course of the production phase. The level of production achieved with this system reached approximately 17 ,g EGFP/106 infected cells. [source] Microarray-based gene expression analysis as a process characterization tool to establish comparability of complex biological products: Scale-up of a whole-cell immunotherapy productBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009Min Wang Abstract Whole-cell immunotherapies and other cellular therapies have shown promising results in clinical trials. Due to the complex nature of the whole cell product and of the sometimes limited correlation of clinical potency with the proposed mechanism of action, these cellular immunotherapy products are generally not considered well characterized. Therefore, one major challenge in the product development of whole cell therapies is the ability to demonstrate comparability of product after changes in the manufacturing process. Such changes are nearly inevitable with increase in manufacturing experience leading to improved and robust processes that may have higher commercial feasibility. In order to comprehensively assess the impact of the process changes on the final product, and thus establish comparability, a matrix of characterization assays (in addition to lot release assays) assessing the various aspects of the cellular product are required. In this study, we assessed the capability of DNA-microarray-based, gene-expression analysis as a characterization tool using GVAX cancer immunotherapy cells manufactured by Cell Genesys, Inc. The GVAX immunotherapy product consists two prostate cancer cell lines (CG1940 and CG8711) engineered to secrete human GM-CSF. To demonstrate the capability of the assay, we assessed the transcriptional changes in the product when produced in the presence or absence of fetal bovine serum, and under normal and hypoxic conditions, both changes intended to stress the cell lines. We then assessed the impact of an approximately 10-fold process scale-up on the final product at the transcriptional level. These data were used to develop comparisons and statistical analyses suitable for characterizing culture reproducibility and cellular product similarity. Use of gene-expression data for process characterization proved to be a reproducible and sensitive method for detecting differences due to small or large changes in culture conditions as might be encountered in process scale-up or unanticipated bioprocess failures. Gene expression analysis demonstrated that cell products of representative lots under the same production process and at the same production scale were statistically identical. Large process changes that resulted from the artificial stress conditions used (absence of FBS and induction of hypoxia) displayed profoundly different gene expression patterns. We propose the use of simple t -test analysis in combination with the herein introduced expression ratio with mean intensity (ERMI) analysis as useful tools for process characterization by global gene expression analysis. Biotechnol. Bioeng. 2009; 104: 796,808 © 2009 Wiley Periodicals, Inc. [source] Processes of Language Acquisition in Children With Autism: Evidence from Preferential LookingCHILD DEVELOPMENT, Issue 2 2007Lauren D. Swensen Two language acquisition processes (comprehension preceding production of word order, the noun bias) were examined in 2- and 3-year-old children (n=10) with autistic spectrum disorder and in typically developing 21-month-olds (n=13). Intermodal preferential looking was used to assess comprehension of subject,verb,object word order and the tendency to map novel words onto objects rather than actions. Spontaneous speech samples were also collected. Results demonstrated significant comprehension of word order in both groups well before production. Moreover, children in both groups consistently showed the noun bias. Comprehension preceding production and the noun bias appear to be robust processes of language acquisition, observable in both typical and language-impaired populations. [source] | ||||||||||