Flow Cytometry is a measurement technique used in Quality Control and in-process measurements of biomanufactured Cell and Gene Therapy products. However, it contains a number of sources of measurement variation at; sample preparation, instrument setup, analysis, and post-analytical data analysis stages. The latter sees variation introduced from operator subjectivity, which is investigated here to understand what effects the interpretation of diagrammatical protocols have on inter-operator analysis.36 operators from different sites were given a series of histograms to analyse, gating a shifting peak. This was repeated with diagrammatical protocols to apply gates which reduced inter-operator variation by up to 92%. Various control limits include and exclude different results and when adjusted with a log transform differences in outlier discrimination have been found. This research supports the use of Flow Cytometry diagrammatical protocols to reduce the contribution of inter-operator variation and measurement uncertainty associated within Cell and Gene Therapy manufacturing scenarios.
Measured variability of product within Cell and Gene Therapy (CGT) manufacturing arises from numerous sources across pre-analytical to post-analytical phases of testing. Operators are a function of the manufacturing process and are an important source of variability as a result of personal differences impacted by numerous factors. This research uses measurement uncertainty in comparison to Coefficient of Variation to quantify variation of participants when they complete Flow Cytometry data analysis through a 5-step gating sequence. Two study stages captured participants applying gates using their own judgement, and then following a diagrammatical protocol, respectively. Measurement uncertainty was quantified for each participant (and analysis phase) by following Guide to the Expression of Uncertainty in Measurement protocols, combining their standard deviations in quadrature from each gating step in the respective protocols. When participants followed a diagrammatical protocol, variation between participants reduced by 57%, increasing confidence in a more uniform reported cell count percentage. Measurement uncertainty provided greater resolution to the analysis processes, identifying that most variability contributed in the Flow Cytometry gating process is from the very first gate, where isolating target cells from dead or dying cells is required. This work has demonstrated the potential for greater usage of measurement uncertainty within CGT manufacturing scenarios, due to the resolution it provides for root cause analysis and continuous improvement.
T HE technique of relaxing selection by random mating in a population or sample of the population after selection for particular traits has a number of useful purposes. The most significant of these is answering the question; how permanent are the genetic gains in the selected trait? From a commercial point of view, if such gains are permanent a purchaser of chicks could keep on reproducing them for a considerable time without loss of performance. This technique has been used by geneticists in selection experiments to help shed light on a number of factors which affect selection. A principal consideration is some estimation of the effect of natural selection which opposes artificial selection if there is negative correlation between the selected trait and fitness components. The subject of relaxed or attenuated selection is discussed rather extensively by Lerner (1950) and by other authors in recent reports of selection experiments. * Published as Paper No. 4150. Scientific Journal Series of the Minnesota Agricultural Experiment Station, St. Paul 1, Minnesota. stad, 1957. Effects of selenium in preventing exudative diathesis in chicks. Proc. Soc. Exp. Biol. Med. 95: 617-620. Reid, B. L., M. M. Rahman, B. G. Creech and J. R. Couch, 1958. Selenium and development of exudative diathesis in chicks. Proc. Soc. Exp. Biol. Med. 97: 590-593. Schwartz, K., J. G. Bieri, G. M. Briggs and M. L. Scott, 1957. Prevention of exudative diathesis in chicks by factor 3 and selenium. Proc. Soc. Exp. Biol. Med. 95: 621-625.The objective of this study was to observe and measure empirically the results of relaxed selection in a strain of White Leghorns previously selected for egg production. The physical facilities available made it impossible to compare more than three generations. DESIGN The genetic stock on which these comparisons were made was secured from a commercial breeder who has been selecting for egg production as well as egg quality factors for a period of approximately twenty-five generations. During this time individual and family selections were made on a closed flock basis. While there is no accurate estimate of how much progress has been made, undoubtedly some has, since this particular stock is well accepted and enjoys a good reputation among commercial egg producers. It was suspected that the parent population performance had reached a plateau since comparative records of the past few years indicated little or no change in egg numbers. During the
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