scholarly journals An important source of preanalytical error in medical laboratories: centrifugation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Cigdem Sonmez ◽  
Alper Gümüş ◽  
Mehmet Senes ◽  
Guzin Aykal ◽  
Fatma Taneli ◽  
...  
Keyword(s):  
Centrifugal Force ◽  
Gravitational Acceleration ◽  
Medical Laboratories ◽  
Electric Device ◽  
Preanalytical Phase ◽  
Plasma And Urine Samples ◽  
Relative Centrifugal Force ◽  
Technical Specifications ◽  
Physical Impact ◽  
Rotor Type

Abstract Centrifugation separates particles within the specimen according to their shape, dimensions, and density and basically can be defined as a separation method. The centrifuge is an essential device in medical laboratories to prepare the serum, plasma, and urine samples for analysis. It is basically an electric device composed of the stationary (motor) and the motile (rotor) part. The centrifugation depends on two main variables: relative centrifugal force (RCF) and centrifugation time. The physical impact separating the specimen into its components in the centrifuge known as RCF is expressed as the multiples of gravitational acceleration (×g). RPM, defined as the number of rotations of the centrifuge per minute, shows the speed of the centrifuge. RCF value can be calculated by using RPM, and the centrifuge radius. Because models and sizes of centrifuges vary considerably, the use of gravity (g) forces instead of RPM is suggested. The centrifuges can be classified according to their usage, speed, technical specifications, and rotor type. An accurate and precise centrifugation process is essential to prevent errors in the preanalytical phase. The purpose of this document is to ensure the standardization of a good, precise protocol for the centrifugation process among the medical laboratories.

scholarly journals Histological characteristics of Platelet-Rich Fibrin clots obtained under various modes of blood centrifugation

2020 ◽  
Vol 22 (99) ◽  
pp. 84-93
Author(s):  
S. N. Shevchenko ◽  
M. V. Rublenko
Keyword(s):  
Centrifugal Force ◽  
Platelet Rich Plasma ◽  
Fibrin Clot ◽  
Biological Properties ◽  
Platelet Rich Fibrin ◽  
Optimal Value ◽  
Relative Centrifugal Force ◽  
Histological Characteristics ◽  
First And Second Generation ◽  
Fibrin Clots

Autologous products of the first and second generation, namely platelet-rich plasma and platelet-rich fibrin, are considered promising for regenerative medicine. They differ from each other in physical properties, as well as in the way they are obtained. The key procedure of all techniques is centrifugation; changing its parameters affects the biological properties of these biomaterials. The aim of the work is to determine and histologically characterize the area of concentration cells of autologous fibrin enriched with platelets, depending on the change in centrifugation parameters. The studies were carried out on rabbits. Blood was collected and platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) were obtained using different values of relative centrifugal force: 100 g, 400 g, 735 g, 906 g, 1843 g. Due to the fact that it is impossible to determine the number of platelets in PRF clots, the counting was performed in platelet-rich plasma obtained by a single centrifugation with the corresponding parameters that were used to obtain PRF. The length of the formed clots was compared and a histological assessment of the cell composition in different layers (lower, middle and upper) was carried out. The highest platelet concentrations were observed in PRP obtained at 100 g and 400 g. Application of different values of centrifugal force showed obvious differences in the formation of platelet-rich fibrin clots. After preparation of I-PRF, its volume was significantly less than that of standard PRF, and the border between erythrocytes was less distinct. During the histological examination of fibrin clots, a change in the distribution of cellular elements in different parts was found with a change in the centrifugation parameters. With an increase in the parameter of relative centrifugal force, the length of the fibrin clot significantly increases, but the concentration of platelets in it significantly decreases. That is, it was found that the most optimal value of the relative centrifugal force for obtaining platelet mass is 100 g, which makes it possible to achieve the number of platelets greater than 800×109/L.

scholarly journals Effects of High g Values on Growth and Chlorophyll Content in Hydrated and Dehydrated Wheat Seeds

2020 ◽  
Vol 21 (2) ◽  
pp. 82
Author(s):  
Sagar Shankar Jagtap ◽  
P. B. Vidyasagar
Keyword(s):  
Chlorophyll Content ◽  
Centrifugal Force ◽  
Present Observation ◽  
Water Medium ◽  
Gravitational Acceleration ◽  
Initial Experiment ◽  
Agar Gel ◽  
Wheat Seedlings ◽  
G Value ◽  
Wheat Seeds

Higher g value stimuli (gravitational acceleration more than 1 g and referred as hyper gravity) caused by centrifugation have been shown to inhibit elongation growth of various plants. In the present study, effects of high g values were studied on wheat seeds with and without water medium at the time of exposure to high g values. Wheat seeds (variety: LOK-1) were washed with 0.5% fungicide and then 4-5 times with distilled water (D/W). Seeds were then soaked in D/W for 24 hrs. Two different experiments were performed. In initial experiment, soaked seeds were taken into the centrifuge tubes filled with 1 ml D/W. Seeds were exposed to hypergravity ranging from 500 g to 2500 g for 10 minutes. In another experiment, soaked seeds were taken into the centrifuge tubes without water or any other medium and then exposed to high g values. After exposure seeds were immediately sowed on 0.8% agar gel. Results obtained showed that exposure to high g values suppressed growth in wheat seedlings when seeds were exposed to high g values with water as a medium. Chlorophyll content also decreased with increase in g. However, no change in growth and chlorophyll content were observed when seeds were exposed without water medium up to g values as high as 2500. Thus, effects of high g value stimuli depend not only on how much centrifugal force is applied to the seeds but also depends upon how much force is experienced by the inner part of the seeds.  Present observation shows that effective centrifugal force experienced by the seeds is different when applied with and without medium.

scholarly journals Relative Centrifugal Force (RCF; G-Force) Affects the Distribution of TGF-β in PRF Membranes Produced Using Horizontal Centrifugation

2020 ◽  
Vol 21 (20) ◽  
pp. 7629
Author(s):  
Zahra Kargarpour ◽  
Jila Nasirzade ◽  
Layla Panahipour ◽  
Richard J. Miron ◽  
Reinhard Gruber
Keyword(s):  
Centrifugal Force ◽  
High Speed ◽  
Target Genes ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Buffy Coat ◽  
Platelet Poor Plasma ◽  
Nadph Oxidase 4 ◽  
Relative Centrifugal Force ◽  
Coat Layer

Solid platelet-rich fibrin (PRF) is produced with centrifugation tubes designed to accelerate clotting. Thus, activated platelets may accumulate within the fibrin-rich extracellular matrix even before centrifugation is initiated. It can thus be assumed that platelets and their growth factors such as transforming growth factor-β (TGF-β) are trapped within PRF independent of their relative centrifugal force (RCF), the gravitation or g-force. To test this assumption, we prepared PRF membranes with tubes where clotting is activated by a silicone-coated interior. Tubes underwent 210 g, 650 g and 1500 g for 12 min in a horizontal centrifuge. The respective PRF membranes, either in total or separated into a platelet-poor plasma and buffy coat fraction, were subjected to repeated freeze-thawing to prepare lysates. Gingival fibroblasts were exposed to the PRF lysates to provoke the expression of TGF-β target genes. We show here that the expression of interleukin 11 (IL11) and NADPH oxidase 4 (NOX4), and Smad2/3 signaling were similarly activated by all lysates when normalized to the size of the PRF membranes. Notably, platelet-poor plasma had significantly less TGF-β activity than the buffy coat fraction at both high-speed protocols. In contrast to our original assumption, the TGF-β activity in PRF lysates produced using horizontal centrifugation follows a gradient with increasing concentration from the platelet-poor plasma towards the buffy coat layer.

A Simplified Preparation for Adenosine Triphosphatase Determination in Gill Tissue

1982 ◽  
Vol 39 (1) ◽  
pp. 215-217 ◽  
Author(s):  
W. S. Zaugg
Keyword(s):  
Centrifugal Force ◽  
High Speed ◽  
Adenosine Triphosphatase ◽  
Room Temperature ◽  
Gill Tissue ◽  
Low Speed ◽  
Relative Centrifugal Force

A simplified preparation from gill tissue that yields adenosine triphosphatase activities comparable to some microsomal fractions is described. The procedure uses two short (6 and 7 min), low speed (2000 Relative Centrifugal Force) centrifugations at room temperature in contrast to long, high speed, refrigerated centrifugations usually associated with microsomal preparations.Key words: gill ATPase, ATPase, fish

scholarly journals Static Mantle Density Distribution 1 Equation

2019 ◽  
pp. 1-8 ◽  
Author(s):  
Tian Quan Yun
Keyword(s):  
Potential Energy ◽  
Density Distribution ◽  
Centrifugal Force ◽  
Seismic Waves ◽  
Vertical Direction ◽  
Gravitational Acceleration ◽  
Minimum Potential Energy ◽  
Fredholm Type ◽  
Minimum Potential ◽  
Two Parameters

The study of mantle distribution does relate to the reflecting of seismic waves, and has important meaning. Using Archimedes Principle of Sink or Buoyancy (APSB), Newton’s gravitation, buoyancy, lateral buoyancy, centrifugal force and the Principle of Minimum Potential Energy (PMPE), we derive equation of static mantle density distribution. It is a set of double-integral equations of Volterra/Fredholm type.  Some new results are: (1) The mantle is divorced into sink zone, neural zone and buoyed zone. The sink zone is located in a region with boundaries of a inclined line, with angle α1=35°15’ apex at  0(0,0,0) revolving around the z-axis, inside the crust involving the equator. The buoyed zone is located in the remainder part, inside the crust involving poles. The neural zone is the boundary between the buoyed and sink zones. The shape of core (in sink zone) is not a sphere. (2) The Potential energy inside the Earth is calculated by Newton’s gravity, buoyancy, centrifugal force and lateral buoyancy. (3) The gravitational acceleration above/on the crust is tested by formula with two parameters reflecting gravity and centrifugal force, and the phenomenon of “heavier substance sinks down in vertical direction due to attraction force, and moves towards to edges in horizontal direction due to centrifugal force” is tested by a cup of stirring coffee.

Effect of Relative Centrifugal Force on the Apparent Size of DNA from Escherichia coli Cells

1973 ◽  
Vol 51 (4) ◽  
pp. 397-406 ◽  
Author(s):  
D. K. Myers ◽  
L. D. Johnson ◽  
K. G. Chetty
Keyword(s):  
Centrifugal Force ◽  
Sedimentation Coefficient ◽  
Apparent Size ◽  
Factors Affecting ◽  
E Coli ◽  
Phage Dna ◽  
Relative Centrifugal Force ◽  
T4 Phage ◽  
Standard Marker ◽  
Marked Dependence

Sedimentation coefficients were determined for the DNA from E. coli cells that had been lysed on top of alkaline sucrose gradients and some of the factors affecting the apparent size of the DNA were explored. Parallel experiments were carried out with the DNA from lysed T4 phage as a standard marker. The apparent size of single-stranded DNA from E. coli is strongly dependent on relative centrifugal force; regardless of the initial size, whether 50 or 140 S, all preparations sedimented at the same rate at high rotor speeds. The size of T4 phage DNA appeared to be too small to show an equally marked dependence of sedimentation coefficient on rotor speed under the conditions tested.Cells washed with EDTA solutions yielded DNA of a smaller size, while cells lysed on alkaline 25–40% sucrose gradients containing 1 M sodium ion yielded DNA with very high sedimentation coefficients.

Sign in / Sign up

Export Citation Format

Share Document