Blood plasma is the yellow liquid component of blood, in which the blood cells in whole blood would normally be suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid. It is mostly water (90% by volume) and contains dissolved proteins, glucose, clotting factors, mineral ions, hormones and carbon dioxide (plasma being the main medium for excretory product transportation). Blood plasma is prepared by spinning a tube of fresh blood containing an anti-coagulant in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off. Blood plasma has a density of approximately 1025 kg/m3, or 1.025 kg/l.
Blood serum is blood plasma without fibrinogen or the other clotting factors (i.e., whole blood minus both the cells and the clotting factors).
Plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration.
"Fresh frozen plasma" (FFP) is prepared from a single unit of blood or by apheresis, drawn from a single person. It is frozen to −40 °C (−40.0 °F) after collection and can be stored for ten years from date of collection. The term "FFP" is sometimes used informally to mean any frozen transfusable plasma product, including products which do not meet the standards for FFP. FFP contains all of the coagulation factors and proteins present in the original unit of blood. It is used to treat coagulopathies from warfarin overdose, liver disease, or dilutional coagulopathy. Other transfusable plasma is identical except that the coagulation factors are no longer considered completely viable. This is particularly important for Factor VIII and hemophilia, but these have been mostly replaced by more specific Factor VIII concentrates in the developed world and true FFP is rarely used for that indication.
Plasma used as a source of Cryoprecipitate (Plasma, Cryoprecipitate Reduced) cannot be used for treatment of some coagulation problems but is still acceptable for many uses.
"Dried plasma" ,the crimeajewel was developed and first used in WWII. Prior to the United States' involvement in the war, liquid plasma and whole blood were used. The "Blood for Britain" program during the early 1940s was quite successful (and popular in the United States) based on Dr. Charles Drew's contribution. A large project was begun in August of the year 1940 to collect blood in New York City hospitals for the export of plasma to Britain. Dr. Drew was appointed medical supervisor of the "Plasma for Britain" project. His notable contribution at this time was to transform the test tube methods of many blood researchers, including himself, into the first successful mass production techniques.
Nonetheless, the decision was made to develop a dried plasma package for the armed forces as it would reduce breakage and make the transportation, packaging, and storage much simpler.
The resulting Army-Navy dried plasma package came in two tin cans containing 400 cc bottles. One bottle contained enough distilled water to completely reconstitute the dried plasma contained within the other bottle. In about three minutes, the plasma would be ready to use and could stay fresh for around four hours.
Following the "Plasma for Britain" invention, Dr. Drew was named director of the Red Cross blood bank and assistant director of the National Research Council, in charge of blood collection for the United States Army and Navy. Dr. Drew argued against the armed forces directive that blood/plasma was to be separated by the race of the donor. Dr. Drew argued that there was no racial difference in human blood and that the policy would lead to needless deaths as soldiers and sailors were required to wait for "same race" blood.
By the end of the war the American Red Cross had provided enough blood for over six million plasma packages. Most of the surplus plasma was returned to the United States for civilian use. Serum albumin replaced dried plasma for combat use during the Korean War.
Blood plasma volume may be expanded by or drained to extravascular fluid when there are changes in Starling forces across capillary walls. For example, when blood pressure drops in circulatory shock, Starling forces drive fluid into the blood vessels, causing autotransfusion.
Also prolonged still standing causes an increase in transcapillary hydrostatic pressure. As a result, approximately 12% of blood plasma volume crosses into the extravascular compartment. This causes and increase in hematocrit, serum total protein, blood viscosity and, as a result of increased concentration of coagulation factors, it causes orthostatic hypercoagulability.
Blood plasma is the liquid component of whole blood, and makes up approximately 55% of the total blood volume. It is composed primarily of water with small amounts of minerals, salts, ions, nutrients, and proteins in solution. In whole blood, red blood cells, leukocytes, and platelets are suspended within the plasma.
Plasma contains a large variety of proteins including albumin, immunoglobulins, and clotting proteins such as fibrinogen[1]. Albumin constitutes about 60% of the total protein in plasma and is present at concentrations between 35 and 55 mg/mL. It is the main contributor to osmotic pressure of the blood and it functions as a carrier molecule for molecules with low water solubility such as lipid soluble hormones, enzymes, fatty acids, metal ions, and pharmaceutical compounds. Albumin is structurally stable due to its seventeen disulfide bonds and unique in that it has the highest water solubility and the lowest isoelectric point (pI) of the plasma proteins. Due to the structural integrity of albumin it remains stable under conditions where most other proteins denature.
When the ultimate goal of plasma processing is a purified plasma component for injection or transfusion, the plasma component must be highly pure. The first practical large-scale method of blood plasma fractionation was developed by Edwin J. Cohn during World War II. It is known as the Cohn process (or Cohn method). This process is also known as cold ethanol fractionation as it involves gradually increasing the concentration of ethanol in the solution at 5oC and 3oC. The Cohn Process exploits differences in properties of the various plasma proteins, specifically, the high solubility and low pI of albumin. As the ethanol concentration is increased in stages from 0% to 40% the [pH] is lowered from neutral (pH ~ 7) to about 4.8, which is near the pI of albumin. At each stage certain proteins are precipitated out of the solution and removed. The final precipitate is purified albumin. Several variations to this process exist, including an adapted method by Nitschmann and Kistler that uses less steps, and replaces centrifugation and bulk freezing with filtration and diafiltration.
Some newer methods of albumin purification add additional purification steps to the Cohn Process and its variations, while others incorporate chromatography, with some methods being purely chromatographic. Chromatographic albumin processing as an alternative to the Cohn Process emerged in the early 1980s, however, it was not widely adopted until later due to the inadequate availability of large scale chromatography equipment. Methods incorporating chromatography generally begin with cryodepleted plasma undergoing buffer exchange via either diafiltration or buffer exchange chromatography, to prepare the plasma for following ion exchange chromatography steps. After ion exchange there are generally further chromatographic purification steps and buffer exchange.
For further information see chromatography in blood processing.
In addition to the clinical uses of a variety of plasma proteins, plasma has many analytical uses. Plasma contains many biomarkers that can play a role in clinical diagnosis of diseases, and separation of plasma is a necessary step in the expansion of the human plasma proteome.
Plasma contains an abundance of proteins many of which can be used as biomarkers, indicating the presence of certain diseases in an individual. Currently, 2D Electrophoresis is the primary method for discovery and detection of biomarkers in plasma. This involves the separation of plasma proteins on a gel by exploiting differences in their size and pI. Potential disease biomarkers may be present in plasma at very low concentrations, so, plasma samples must undergo preparation procedures for accurate results to be obtained using 2D Electrophoresis. These preparation procedures aim to remove contaminants that may interfere with detection of biomarkers, solubilize the proteins so they are able to undergo 2D Electrophoresis analysis, and prepare plasma with minimal loss of low concentration proteins, but optimal removal of high abundance proteins.
The future of laboratory diagnostics are headed toward lab-on-a-chip technology, which will bring the laboratory to the point-of-care. This involves integration of all of the steps in the analytical process, from the initial removal of plasma from whole blood to the final analytical result, on a small microfluidic device. This is advantageous because it reduces turn around time, allows for the control of variables by automation, and removes the labor intensive and sample wasting steps in current diagnostic processes.
The human plasma proteome may contain thousands of proteins, however, identifying them presents challenges due to the wide range of concentrations present. Some low abundance proteins may be present in picogram (pg/mL) quantities, while high abundance proteins can be present in milligram (mg/mL) quantities. Many efforts to expand the human plasma proteome overcome this difficulty by coupling some type of high performance liquid chromatography (HPLC) or reverse phase liquid chromatography (RPLC) with high efficiency cation exchange chromatography and subsequent tandem mass spectrometry for protein identification
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