Plasma and Serum
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Blood consists of plasma in which erythrocytes, leucocytes and thrombocytes (platelets) are suspended.
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Plasma, in turn consists of serum and fibrinogen.
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Action of thrombin on fibrinogen separates out fibrin.
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Serum is rich in albumin and globulin.
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Thus, plasma is recovered from unclotted blood by centrifugation, whereas serum is obtained from clotted blood.
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It may be noted that normal blood clotting time of most domestic animals is 3 to 6 minutes.
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Only from those abattoirs where slaughter is carried out on bleeding rails blood can be collected for human use.
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Trocar knife (with hollow handle) and canula are used for hygienic recovery of blood, which is collected in clean and sterile stainless containers.
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An ideal vessel should have a diameter of 45 cm and a depth of 15 cm.
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It can be washed with hypochlorite or steam sterilized.
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To prepare plasma
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To prepare serum
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blood is collected carefully and allowed to clot and subjected to further processing in a cold room.
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Chilled clotted blood is cut into smaller lumps to bring about quick contraction of clots.
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Serum collected in first 12 hours is generally clear except for some suspended RBCs.
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It is centrifuged in a bucket centrifuge at 100 rpm and filtered through Seitz filter.
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The yield of serum is about 10-12% of the weight of whole blood.
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It keeps well at 4-5oC for one month and at –20oC for six months.
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Dried blood serum is referred as blood albumen and is used as the cheapest substitute for dried egg albumen powder in the industry.
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To prepare it, to clear yellow serum is added 0.05% phenol on weight basis.
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It is sprayed or vacuum dried to soluble fine powder.
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The yield of albumen is 10-20% of the weight of the serum.
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It is stable in airtight containers in cool places for several months.
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Last modified: Thursday, 16 September 2010, 6:23 AM