Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002874 (aplastic anemia)
 5,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By using a combination of a heterologous antiserum to GPIb/glycocalicin and a radiolabeled monoclonal antibody to GPIb/glycocalicin, we were able to develop a sensitive and specific radioimmunoelectrophoretic assay that can distinguish small amounts of glycocalicin from GPIb. Normal plasmas were found to contain glycocalicin, even in samples treated with protease inhibitors and centrifuged extensively to remove platelets and platelet fragments. Confirmation that the plasma antigen had a relative molecular weight similar or identical to glycocalicin was obtained from studies employing gel chromatography and affinity chromatography. An immunoradiometric assay was developed to quantify plasma glycocalicin, and normal plasma was found to contain approximately 1-3 micrograms/ml. The plasma of a patient with severe thrombocytopenia due to aplastic anemia had less than 12.5% of the normal level of glycocalicin, whereas two patients with thrombocytopenia due to diseases of increased platelet destruction (idiopathic thrombocytopenic purpura and hemolytic-uremic syndrome) had normal levels. Thus, there appears to be ongoing catabolism of platelet GPIb in vivo, and we postulate that the plasma level of glycocalicin reflects a complex function of factors, including platelet count, platelet turnover, and the site of platelet destruction.
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PMID:Evidence that glycocalicin circulates in normal plasma. 623 8

Platelet glycocalicin (GC) is the extramembranous portion of GPIb alpha that can be rapidly cleaved by enzymes such as calpain, plasmin, trypsin, elastase, etc. Quantitative cleavage will ultimately result in an acquired Bernard-Soulier-like bleeding disorder, and circulating GC may act as a potential inhibitor of platelet adhesion. We have developed and standardized a new enzyme-linked immunosorbent assay (ELISA), which uses two monoclonal antibodies (mAbs), both of which bind to the amino-terminal 45-kD fragment of GC and inhibit platelet-von Willebrand interactions and the streptavidin-biotin system. First, the methodology was evaluated and standardized with special emphasis on the anticoagulant and the inhibitors (EDTA, prostaglandin E1 [PGE1], aprotinin, N-ethyl-maleimide), the mode of high-speed centrifugation (to avoid platelet microparticles), and the standards used (purified GPIb and GC). This assay was then used to analyze the GC levels of healthy subjects (2.04 +/- 0.46 micrograms/mL) and of patients with selected diseases. The results of patients with aplastic anemia and thrombocytosis confirmed that GC levels are clearly dependent on the platelet count, which was the basis for the introduction of the GC index, the standardization of GC for a platelet count of 250 x 10(9)/L. The GC index discriminates reliably patients with active immune thrombocytopenic purpura from those in remission. GC levels are elevated in patients on hemodialysis (3.62 +/- 0.75 micrograms/mL, P < .001). The high GC index (6.93 +/- 4.21, P < .001) in cirrhosis patients suggests an increased platelet turnover and/or abnormal proteolysis. In contrast to other groups, we have not found that recombinant tissue plasminogen activator (rtPA) treatment of patients with myocardial infarction increases GC levels. However, concentrations are elevated in leukemia and the highest levels found are approximately 40 micrograms/mL. These studies suggest that GC is a useful platelet marker in certain diseases, which directly reflects platelet damage and possibly platelet dysfunction.
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PMID:Glycocalicin: a new assay--the normal plasma levels and its potential usefulness in selected diseases. 829 32

To detect levels of platelet glycoprotein-specific autoantibody in idiopathic thrombocytopenic purpura (ITP), chronic aplastic anemia (CAA), hematologic malignancies and healthy volunteers, and evaluate the clinical significance of platelet glycoprotein-specific autoantibody level in diagnosis for ITP, anti-GPIb/IX, anti-GPIIb/IIIa, anti-GPIV and anti-GPV auto-antibodies were detected contemporaneously by a modified monoclonal antibody immobilization of platelet antigen assay (modified MAIPA). The results showed that the total positive rate of antibodies against platelet GPIb/IX, GPIIb/IIIa, GPIV, GPV were 69.99%, 10%, 20% and 0% in ITP, CAA, hematologic malignancy group and healthy volunteers respectively. There was significant difference between ITP and CAA (chi(2) = 20.71, P < 0.005), between ITP and hematologic malignancy group (chi(2) = 12.22, P < 0. 005). There was no positive finding in the healthy control. It is concluded that platelet glycoprotein-specific autoantibody has high value for the diagnosis of ITP,many kinds of antibodies detection at one time can enhance sensitivity, MAIPA is a specific assay for the diagnosis of idiopathic thrombocytopenic purpura.
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PMID:[The diagnostic value of platelet glycoprotein-specific autoantibody detection in idiopathic thrombocytopenic purpura]. 1515 34