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Antimicrobial Preservative Efficacy and Microbial Content Testing*
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Scott V.W. Sutton, Philip A. Geis
In a somewhat opinionated article, Gilbert et al. describe several aspects of inocula preparation of concern for reducing variability in antimicrobial tests through tight control of the inocula (76). Of particular interest in this article are the discussions on the growth on solid agar and the difficulties in generating reproducible inocula due to differences in growth rates. Liquid growth is recommended, however, in another article (77). Gilbert et al. describe injury to the challenge organism Pseudomonas aeruginosa by centrifugation. One is left with a dilemma: how to grow organisms in liquid media (and so enhance reproducibility) while avoiding problems of media carry-over into the product tested. The pharmacopeias have elected to allow centrifugation.
Definition of HLA-Dw Determinants Using Homozygous Typing Cells and the Mixed Lymphocyte Culture
Published in M. Kam, Jeffrey L. Bidwell, Handbook of HLA TYPING TECHNIQUES, 2020
The frozen vials are rapidly placed in a rack in a 37°C water bath. In order to prevent explosion of the vials, the tops of the tubes should be loosened before placing them in the water bath. Immediately after thawing, each cell suspension is transferred to a sterile culture tube and diluted with a minimum of 5 ml of cold RPMI 1640 medium containing 10% PHS. Cells should never be left at room temperature in the presence of DMSO as it is toxic. The cell suspension is washed twice and then resuspended in 2 ml of culture medium. Cell concentration is adjusted to 10 × 106 cells per milliliter and the viability checked by the trypan blue exclusion method or by using a phase contrast microscope. If the viablity is <80%, the dead cells should be removed by Ficoll-Hypaque gradient centrifugation.
Alternative drug combination to treat chronic myeloid leukemia resistance in developing countries
Published in Ade Gafar Abdullah, Isma Widiaty, Cep Ubad Abdullah, Medical Technology and Environmental Health, 2020
A.F. Sumantri, A. Oehadian, M.H. Bashari
Procedure for mononuclear cell isolation was carried out using Ficoll-Paqque media and then inserted into centrifugation tubes of 3 ml and carefully poured 4 ml of peripheral blood specimens to form layers of blood samples and Ficoll-Paqque media. Centrifugation was carried out at a speed of 400 g for 30–40 minutes at a temperature of 18–20°C. After that, the researchers moved the mononuclear cell layer into a sterile centrifugation tube and then calculated viability of the cells before the cells were treated, and then analyzed by researchers.
Effects of platelet-rich fibrin produced by three centrifugation protocols on bone neoformation in defects created in rat calvaria
Published in Platelets, 2023
Débora de Souza Ferreira Sávio, Lucia Moitrel Pequeno da Silva, Gabriel Guerra David Reis, Ricardo Junior Denardi, Natacha Malu Miranda da Costa, Flávia Aparecida Chaves Furlaneto, Sérgio Luís Scombatti de Souza, Carlos Fernando de Almeida Barros Mourão, Richard J. Miron, Roberta Okamoto, Michel Reis Messora
The present study produced PRF matrices using high and low-speed centrifugation. In vitro, studies have demonstrated better cellular and molecular characteristics in low-speed centrifugation protocols.1,28,49,50 It is thus assumed that structural changes in PRF clots may alter their regenerative potential. In all parameters analyzed in this study, no statistically significant differences were found between the L-PRF and A-PRF groups, which supports the findings of Silva et al. (2022),37 where the two different types of PRF matrices promoted greater bone neoformation compared to the control group, in microtomographic and histomorphometric parameters, but there were no significant differences between them. Higher rates of release of important growth factors for the promotion of bone neoformation have been demonstrated in low-speed centrifugation protocols compared to the original high-speed centrifugation protocols.24,28
Enrichment of plasma in platelets and extracellular vesicles by the counterflow to erythrocyte settling
Published in Platelets, 2022
Darja Božič, Domen Vozel, Matej Hočevar, Marko Jeran, Zala Jan, Manca Pajnič, Ljubiša Pađen, Aleš Iglič, Saba Battelino, Veronika Kralj-Iglič
Mathematical model is an important tool for interpretation of measurements. It provides insight into the mechanism why and how parameters influence the quantities of interest. For example, based on the model, the CP and the time of centrifugation can be estimated for an individual sample (Equation (4)) for which the highest yield of platelets and/or EVs can be expected (Equation (6)). The model was constructed based on the experimental part of this study, which was set by a previously used protocol that was equal for all samples [8]. It was however observed during the study that the volumes of EPP obtained by the same CP and time of centrifugation of blood differed considerably although the hematocrit values of the samples did not vary much. This indicated that the efficiency of centrifugation could be increased by individualization of the centrifuge setting. To achieve the optimal setting, the model is necessary. In the future, a prospective clinical study should be made to validate the prediction and possibly imply improvements in the model to finally get to a practical advice (a formula or a computer application) how to determine CP and the centrifugation time in clinical practice for a given sample, based on the results of the standard laboratory blood test.
Small extracellular vesicles (sEVs): discovery, functions, applications, detection methods and various engineered forms
Published in Expert Opinion on Biological Therapy, 2021
Manica Negahdaripour, Hajar Owji, Sedigheh Eskandari, Mozhdeh Zamani, Bahareh Vakili, Navid Nezafat
Indeed, traditional sEV isolation techniques and technical standardized methods suffer from several disadvantages resulting in undesirable outcomes. Recent surveys have therefore focused on improving traditional methods especially toward the establishment of nano-based techniques (Table 2). Various sEV characteristics including density, shape, size, and surface proteins are employed in traditional methods. The methods such as centrifugation, filtration, precipitation, immunoisolation, and liquid chromatography techniques fall into the traditional category [122]. Differential centrifugation is rationally the most basic method that could be used widely for the isolation of sEVs from cell-culture medium or body fluids (urine, saliva, semen, blood, and so on). The vesicle size overlapping of sEVs, microvesicles, and apoptotic bodies prevents sEV isolation from microvesicles and apoptotic bodies through differential centrifugation [123].