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see bloodblood,
fluid pumped by the heart that circulates throughout the body via the arteries, veins, and capillaries (see circulatory system; heart). An adult male of average size normally has about 6 quarts (5.6 liters) of blood.
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The liquid portion that remains when blood is allowed to clot spontaneously and is then centrifuged to remove the blood cells and clotting elements. It has approximately the same volume (55%) as plasma and differs from it only by the absence of fibrinogen. See Fibrinogen

Blood serum contains 6–8% solids, including macromolecules such as albumin, antibodies and other globulins, and enzymes; peptide and lipid-based hormones; and cytokines; as well as certain nutritive organic materials in small amounts, such as amino acids, glucose, and fats. Somewhat less than 1% of the serum consists of inorganic substances. Small amounts of respiratory gases are dissolved in the serum, as is the gas nitric oxide, which serves as a chemical messenger and vasodilator. Small amounts of waste material are also present. These substances, along with other small molecules which are not bound to blood proteins, are filtered out as blood flows through the kidney. See Blood, Kidney

Certain types of sera, both human and animals, are used in clinical medicine. Immune serum and hyperimmune serum either are developed by naturally occurring disease or are deliberately prepared by repeated injection of antigens to increase antibody titer for either diagnostic tests or the treatment of active disease. These sera are referred to as antisera, since they have a specific antagonistic action against specific antigens. See Antibody, Antigen, Biologicals, Immunity

By custom, the clear portion of any liquid material of animal origin separated from its solid or cellular elements is also referred to as sera. These fluids are more properly referred to as effusions. See Serology


The liquid portion that remains when blood clots spontaneously and the formed and clotting elements are removed by centrifugation; it differs from plasma by the absence of fibrinogen.


1. See blood serum
2. antitoxin obtained from the blood serum of immunized animals
3. Physiol zoology clear watery fluid, esp that exuded by serous membranes
References in periodicals archive ?
Impact of 24,25[(OH).sub.2][D.sub.3] in sera from DEQAS samples in percent bias from target values as measured by the NIST reference measurement procedure.
Values for total bilirubin in human and bovine sera enriched with UBIL and DTB, as measured with the reference method and 7 chemistry analyzers.
Serologic tests for acute pulmonary histoplasmosis are helpful to confirm the diagnosis, particularly in patients with mild disease by collection of both acute and convalescent sera; this is true because antibodies usually require at least 1 month to appear after the initial exposure (Wheat 2001).
With the Vitros F[T.sub.3]II assay, the F[T.sub.3] concentrations in sera from 2 patients with antibodies to [T.sub.2], [T.sub.3], or their conjugates decreased 71% and 55% with dilution.
However, despite observation that by immunoblotting the sera of HEW- and CM-sensitized rats showed IgE antibodies to the main allergens in HEW and CM, only a low number of IgE responders were observed as measured by PCA.
The method used here to analyze natural infection can be applied to clinical trials of candidate vaccines, and we expect this test to be equally applicable to animal sera.
The standard growth conditions for these cell lines entail the addition of different sera and their associated proteins, so it is difficult to compare the actual vulnerability of gliotypic and neuronotypic cell lines (1,18).
When sera taken from IDA patients are stored for a long time before being measured, there is a possibility that, in some assay systems, values may be underestimated because TfR free of Tf, which is found predominantly in IDA sera, readily loses its immunologic reactivity.
In the first stage, a set of putative prostate cancer biomarkers was identified by comparing sera from five patients whose prostate cancer showed capsular penetration with sera from five cancer-free controls.
As control sera, we used 200 paired samples from patients with community-acquired pneumonia seen at NTUH from October 2001 to December 2002, 70 serum samples from hospitalized patients with acute respiratory distress syndrome treated in 2002 at the hospital, and 10 serum samples obtained from 10 pregnant women during routine pre-labor check-ups in 2002.
Calibrators were sera containing 1.5, 2.0, 2.5, 3.0, and 4.0 mmol/L calcium, which were prepared by dissolving Ca[Cl.sub.2] in the calcium-free pooled human serum.