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centrifuge and rcf

Alica Kubesch, Mike Barbeck, Sarah Al-Maawi, Anna Orlowska, Patrick F Booms, Robert A Sader, Richard J Miron, Charles J Kirkpatrick, Joseph Choukroun, Shahram Ghanaati
Platelet-rich fibrin (PRF) is generated from the patients' own venous blood by a single centrifugation step without the additional use of anticoagulants. Based on the previously described LSCC (low-speed centrifugation concept), our group showed that modification of the centrifugation setting, that is, reducing the relative centrifugal force (RCF) and mildly increasing the centrifugation time, resulted in modified solid and liquid PRF-matrices with increased number of platelets, leukocytes, and growth factors' concentrations...
March 6, 2018: Platelets
Simon Wend, Alica Kubesch, Anna Orlowska, Sarah Al-Maawi, Niklas Zender, Andre Dias, Richard J Miron, Robert Sader, Patrick Booms, C James Kirkpatrick, Joseph Choukroun, Shahram Ghanaati
Platelet rich fibrin (PRF) is a blood concentrate system obtained by centrifugation of peripheral blood. First PRF matrices exhibited solid fibrin scaffold, more recently liquid PRF-based matrix was developed by reducing the relative centrifugation force and time. The aim of this study was to systematically evaluate the influence of RCF (relative centrifugal force) on cell types and growth factor release within injectable PRF- in the range of 60-966 g using consistent centrifugation time. Numbers of cells was analyzed using automated cell counting (platelets, leukocytes, neutrophils, lymphocytes and monocytes) and histomorphometrically (CD 61, CD- 45, CD-15+, CD-68+, CD-3+ and CD-20)...
October 25, 2017: Journal of Materials Science. Materials in Medicine
Yan Li, Ran Andy Mei, Zhongqiang Yang
This study demonstrates a new process for preparation of oil-in-water (O/W) emulsion using the high gravity technique. This involves a mixture of oil and water that are passed through a rotating packed bed, under a high shear force, from which oil is emulsified into tiny droplets and subsequently dispersed in water. The process is cycled in order to break the droplets repeatedly and achieve an emulsion with small size and low polydispersity index (PDI). The advantage of the high gravity technique is that the emulsions with a desired size and polydispersity can be rapidly obtained by tuning experimental parameters, such as relative centrifugal force (RCF), cycle times (CT), liquid flow rate (VL) and surfactant concentration (Csurfactant)...
November 15, 2017: Journal of Colloid and Interface Science
Si-Gong Zhang, Yu-Xin Song, Xiao-Ming Shu, Hai-Li Shen, Han-Bo Yang, Rui-Xue Duo, Guo-Chun Wang
OBJECTIVE: Low-density granulocytes (LDGs) can form neutrophil extracellular traps (NETs) spontaneously and excessively. When peripheral blood mononuclear cells (PBMCs) are used for studying T lymphocytes, LDGs contained in the PBMCs may decrease the threshold of activating T lymphocytes by forming NETs. This study focused on the profiles of LDGs in common autoimmune diseases and methods for removing LDGs from PBMCs. METHODS: The percentages of LDGs in PBMCs from 55 patients with dermatomyositis (DM), 15 with polymyositis (PM), 42 with rheumatoid arthritis (RA), 25 with systemic lupus erythematosus (SLE), and 19 healthy controls were determined by flow cytometry...
July 2017: Journal of Zhejiang University. Science. B
K El Bagdadi, A Kubesch, X Yu, S Al-Maawi, A Orlowska, A Dias, P Booms, E Dohle, R Sader, C J Kirkpatrick, J Choukroun, S Ghanaati
Purpose The present study evaluated the platelet distribution pattern and growth factor release (VEGF, TGF-β1 and EGF) within three PRF (platelet-rich-fibrin) matrices (PRF, A-PRF and A-PRF+) that were prepared using different relative centrifugation forces (RCF) and centrifugation times. Materials and methods immunohistochemistry was conducted to assess the platelet distribution pattern within three PRF matrices. The growth factor release was measured over 10 days using ELISA. Results The VEGF protein content showed the highest release on day 7; A-PRF+ showed a significantly higher rate than A-PRF and PRF...
March 21, 2017: European Journal of Trauma and Emergency Surgery: Official Publication of the European Trauma Society
J Choukroun, S Ghanaati
PURPOSE: The aim of this study was to analyze systematically the influence of the relative centrifugation force (RCF) on leukocytes, platelets and growth factor release within fluid platelet-rich fibrin matrices (PRF). MATERIALS AND METHODS: Systematically using peripheral blood from six healthy volunteers, the RCF was reduced four times for each of the three experimental protocols (I-III) within the spectrum (710-44 g), while maintaining a constant centrifugation time...
March 10, 2017: European Journal of Trauma and Emergency Surgery: Official Publication of the European Trauma Society
Chia-Wei Chang, Ying-Chih Liao
In this work, the long-term stability of titanium oxide nanowire suspensions was accessed by an accelerated sedimentation with centrifugal forces. Titanium oxide (TiO2) nanoparticle (NP) and nanowire (NW) dispersions were prepared, and their sizes were carefully characterized. To replace the time-consuming visual observation, sedimentation velocities of the TiO2 NP and NW suspensions were measured using an analytical centrifuge. For an aqueous TiO2 NP suspension, the measured sedimentation velocities were linearly dependent on the relative centrifugal forces (RCF), as predicted by the classical Stokes law...
December 27, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Wei Jiang, Rui Hua, Mengping Wei, Chenhong Li, Zilong Qiu, Xiaofei Yang, Chen Zhang
Lentiviral technology has proven to be a powerful tool to express exogenous genes in dividing and non-dividing cells. Currently, most protocols for generating high-titer lentivirus require ultracentrifugation, which can be an instrumental barrier for routine operations in a laboratory. In this study, the effect of relative centrifugal force (RCF) on the concentration efficiency of the lentivirus was systematically explored, and it was found that sucrose gradient centrifugation with a relatively low speed (≤10,000 g) robustly produces a high-titer virus (up to 2×10(8) TU/ml)...
2015: Scientific Reports
Qian Li, Chen-Guang Liu, Yu Yu
Four batches of oleoyl alginate ester (OAE) nanoparticles with narrow size distribution were rapidly separated from the initial batch of nanoparticles by means of centrifugation at the relative centrifugal force (RCF) between 270×g and 6750×g after adjusting the zeta potential. The size of nanoparticles decreased with increasing speed of centrifugation, and the polydispersity of nanoparticles significantly decreased. As particle size increased the loading capacity also increased, while transport across Caco-2 cells and the cellular uptake of nanoparticles in jejunum decreased...
June 25, 2015: Carbohydrate Polymers
M Delahaye, K Lawrence, S J Ward, M Hoare
An ultra scale-down method is described to determine the response of cells to recovery by dead-end (batch) centrifugation under commercially defined manufacturing conditions. The key variables studied are the cell suspension hold time prior to centrifugation, the relative centrifugal force (RCF), time of centrifugation, cell pellet resuspension velocities, and number of resuspension passes. The cell critical quality attributes studied are the cell membrane integrity and the presence of selected surface markers...
May 2015: Biotechnology and Bioengineering
Amal S Abu Almakarem, Katie L Heilman, Heather L Conger, Yury M Shtarkman, Scott O Rogers
BACKGROUND: When samples are collected in the field and transported to the lab, degradation of the nucleic acids contained in the samples is frequently observed. Immediate extraction and precipitation of the nucleic acids reduces degradation to a minimum, thus preserving accurate sequence information. An extraction method to obtain high quality DNA in field studies is described. FINDINGS: DNA extracted immediately after sampling was compared to DNA extracted after allowing the sampled tissues to air dry at 21°C for 48 or 72 hours...
2012: BMC Research Notes
M Merolla, M A Nardi, J S Berger
BACKGROUND: Light transmission aggregometry (LTA) is considered the gold standard for investigating platelet activity ex vivo. However, LTA protocols are not standardized, and differences in LTA procedure are a potential source of variance in results. Centrifugation speed is an essential component of platelet preparation in LTA, has yet to be standardized, and may affect platelet aggregation results. We sought to investigate the effect of relative centrifugal force (RCF) intensity on LTA results...
February 2012: International Journal of Laboratory Hematology
Zhanwen Xing, Jinrui Wang, Hengte Ke, Bo Zhao, Xiuli Yue, Zhifei Dai, Jibin Liu
Novel biocompatible nanobubbles were fabricated by ultrasonication of a mixture of Span 60 and polyoxyethylene 40 stearate (PEG40S) followed by differential centrifugation to isolate the relevant subpopulation from the parent suspensions. Particle sizing analysis and optical microscopy inspection indicated that the freshly generated micro/nanobubble suspension was polydisperse and the size distribution was bimodal with large amounts of nanobubbles. To develop a nano-sized contrast agent that is small enough to leak through tumor pores, a fractionation to extract smaller bubbles by variation in the time of centrifugation at 20g (relative centrifuge field, RCF) was suggested...
April 9, 2010: Nanotechnology
(no author information available yet)
This appendix provides r(max) values (the maximum value of the rotating radius between the particle being centrifuged and the axis of rotation) for commonly used rotors manufactured by Du Pont (Sorvall), Beckman, Fisher, and IEC. Additionally, nomograms are provided for determining the relative centrifugal force (RCF) where speed and r(max) are known, or the speed where RCF and r(max) are known.
May 2001: Current Protocols in Protein Science
(no author information available yet)
This appendix provides rmax (the distance between the axis of rotation and the bottom of the centrifuge tube as it sits in the well or bucket of the rotor) values for commonly used rotors manufactured by Du Pont (Sorvall), Beckman, Fisher, and IEC. Nomograms are also given to determine the relative centrifugal force (RCF) where speed and rmax are known, or the speed where RCF and rmax are known.
May 2001: Current Protocols in Human Genetics
Tae-Wan Kim, Jung-Won Keum, In-Seok Oh, Cha-Yong Choi, Chang-Gil Park, Dong-Myung Kim
In this study, as a part of our efforts to improve the robustness and economical feasibility of cell-free protein synthesis, we developed a simple method of preparing the cell extracts used for catalyzing cell-free protein synthesis reactions. We found that the high-speed centrifugation, pre-incubation, and dialysis steps of the conventional procedures could be omitted without losing the translational activity of the resulting cell extract. Instead, a simple centrifugation step at low speed (12,000 RCF for 10 min) followed by a brief period of incubation was sufficient for the preparation of an active extract to support cell-free protein synthesis with higher productivity and consistency...
December 1, 2006: Journal of Biotechnology
Catherine D Reyes, Andrés J García
A quantitative analysis of cell adhesion is essential in understanding physiological phenomena and designing biomaterials, implant surfaces, and tissue-engineering scaffolds. The most common cell adhesion assays used to evaluate biomaterial surfaces lack sensitivity and reproducibility and/or require specialized equipment and skill-intensive operation. We describe a modified centrifugation cell adhesion assay that uses simple and convenient techniques with standard laboratory equipment and provides reliable, quantitative measurements of cell adhesion...
October 1, 2003: Journal of Biomedical Materials Research. Part A
John M Graham
The formation of self-generated gradients of iodixanol from a solution of uniform concentration requires the use of vertical or near-vertical rotors. The density profile that is generated depends upon the sedimentation path length of the rotor, centrifugation time, RCF and temperature. Modulation of the starting concentration changes the density range of the gradient. This Protocol Article illustrates the effect of these parameters on gradient shape in a few selected rotors. Because the gradients are formed by the centrifugal field, they are highly reproducible and easy to execute...
May 16, 2002: TheScientificWorldJournal
J Perera, D M Arachchi
Direct microscopy is the only available method for diagnosis of tuberculosis in most centres in developing countries. Methods to improve the sensitivity of direct smear are an urgent requirement. Sputum specimens artificially seeded with known concentrations of Mycobacterium tuberculosis were liquefied and decontaminated with sodium hydroxide-sodium citrate-N-actyl-L-cysteine solutions. They were subjected to different centrifugation forces and centrifugation times after which the centrifuged deposits were examined by smear and culture...
July 1999: Transactions of the Royal Society of Tropical Medicine and Hygiene
H C Margolis, Y P Zhang, J van Houte, E C Moreno
Pooled plaque samples were obtained from (1) coronal surfaces of two groups of caries-free (CF) subjects, (2) coronal 'white-spot' surface areas of a group of caries-positive (CP) subjects, and (3) exposed, sound root surfaces of root caries-free (RCF) and root caries-positive (RCP) subjects. The plaque samples were obtained before and 3 min after a 1 min rinse with a 0.5, 1, 2, 5 and 10% sucrose solution. Plaque fluid was then isolated from each plaque sample by centrifugation and analyzed for inorganic ions, organic acids, and pH values...
1993: Caries Research
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