Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Von Willebrand factor (vWF) is a glycoprotein that appears to play a major role in subserving the adhesion of platelets to subendothelium during hemostasis. Endothelial cells have been shown capable of synthesizing and releasing this large, multimeric glycoprotein that normally circulates in the plasma in association with the factor VIII coagulant molecule. Megakaryocytes, the precursor cells of blood platelets, also appear to possess vWF biosynthetic capacity, since cultured guinea pig megakaryocytes have been shown to produce a polypeptide precipitable by antibody to vWF. We now report a study of the multimeric structure of vWF in the megakaryocyte, as well as a quantitative comparison of megakaryocyte vWF with that of platelets and plasma in the guinea pig. Multimeric analysis on SDS agarose gels employing 125I-emu anti-human vWF revealed striking homology between human and guinea pig vWF. Platelets and megakaryocytes from the same guinea pigs contained vWF of highly comparable multimeric composition. Moreover, megakaryocytes and platelets both contained a subset of very high molecular weight multimers not present in plasma. Quantitation of vWF in megakaryocytes and platelets was achieved with a radioimmunoassay performed on detergent (NP-40) lysates of washed cells. These measurements showed that megakaryocytes and platelets contain 0.079 and 0.069 U of vWF per mg protein, respectively. The results of these studies suggest that megakaryocytes represent the primary, if in fact not sole, source of platelet vWF.
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PMID:Multimeric analysis of von Willebrand factor in megakaryocytes. 387 63

Laboratory investigation of an acquired haemorrhagic diathesis in a 63-year-old man with malignant lymphoma revealed the classical haemostatic defects found in von Willebrand's disease (vWD). In addition, SDS-agarose gel electrophoresis demonstrated alterations of the von Willebrand factor (vWF) multimeric structure. A profound defect of large and intermediate size multimers was observed which was different from those seen in variants of congenital vWD. In vitro, weak inhibitory activity against factor VIII procoagulant activity and ristocetin cofactor activity was present in the patient's plasma. When patient's plasma was incubated with normal plasma, followed by centrifugation, vWF antigen (vWF:Ag) was precipitated. In vivo, after transfusion of cryoprecipitate, there was rapid plasma clearance of vWF:Ag and ristocetin cofactor and of FVIII coagulant activities.
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PMID:Profound alterations of the multimeric structure of von Willebrand factor in a patient with malignant lymphoma. 392 29

Factor VIII concentrates have been shown to have reduced ability to correct the bleeding time defect in von Willebrand's disease and to have abnormal mobility of their VIIIR:Ag on crossed immunoelectrophoresis. This report concerns the partial characterization of a fragment of VIIIR:Ag that lacks some of the normal antigenic determinants present on VIIIR:Ag. It is present in commercial factor VIII concentrates, but not in cryoprecipitate, and is recovered from the plasma of hemophilic patients who have been infused with these concentrates. The fragment is also produced during disseminated intravascular coagulation. Although it has a similar mobility on SDS agarose electrophoresis to the smallest multimer of VIIIR:Ag, they are not immunologically identical.
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PMID:Specific factor VIII-related antigen fragmentation: an in vivo and in vitro phenomenon. 618 Jul 85

FVIII/VWF in plasma and platelets was studied by various methods in 16 patients with von Willebrand's disease. These methods included measurements of both VIIIR:Ag and VIIIR:RCo levels, radio-crossed immunoelectrophoresis, analysis of the dose-response curves with both fluid-phase and two-site immunoradiometric assays, and SDS-agarose-acrylamide gel electrophoresis. Studies of normal plasma and platelets by the last-named method disclosed the presence of nine to 10 clearly resolvable bands with molecular weights of approximately 1 to 10 X 10(6) and unresolved higher-molecular-weight material, consistent with the previously described multimeric structure of FVIII/VWF. The multimeric structure and antigenic reactivity of FVIII/VWF were normal in 11 patients with type I von Willebrand's disease. However, measurements of the VIIIR:Ag content in plasma and platelets disclosed the presence of three subgroups. In one (type I-1), the VIIIR:Ag content of both plasma and platelets was decreased; in type I-2, VIIIR:Ag was decreased in plasma but normal in platelets, whereas the reverse was found in two patients with type I-3. In five patients with type IIA von Willebrand's disease we observed various abnormalities in the multimeric structure and antigenic reactivity of FVIII/VWF. The distinguishing features in two patients, designated type IIA-1 and IIA-2, were a decreased amount of high-molecular-weight FVIII/VWF and an impaired antigenic reactivity in both plasma and platelets; the defects in type IIA-2 were qualitatively different and more strikingly abnormal than those in type IIA-1. In three other patients, designated type IIIA-3, a less severe deficit of high-molecular-weight FVIII/VWF in plasma was observed and, in addition, the multimeric structure of FVIII/VWF in platelets was normal. The findings in this study demonstrate that a variety of defects in the synthesis, release, antigenic reactivity, and multimerization of FVIII/VWF are probably responsible for the heterogeneous findings in patients with von Willebrand's disease.
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PMID:Heterogeneous abnormalities in the multimeric structure, antigenic properties, and plasma-platelet content of factor VIII/von Willebrand factor in subtypes of classic (type I) and variant (type IIA) von Willebrand's disease. 618 57

Pretreatment of platelets with chymotrypsin dose-dependently decreased glycoprotein (GP)-Ib amounts as measured by SDS-PAGE, ristocetin-induced agglutination and platelet electrophoretic mobility (EPM). Decrease in platelet EPM in response to 0.75 mg/ml ristocetin alone were 7.0 +/- 2.3 and 6.8 +/- 4.3% (M +/- S.E., n = 6) for control and chymotrypsin-treated platelets, respectively (p greater than 0.2). Von Willebrand factor (vWF) alone had no effect on platelet EPM. However, in the presence of 0.75 mg/ml ristocetin, added vWF (2.9 micrograms/ml) caused a further 6.3 +/- 3.8% decrease in control platelet EPM, but caused no significant decrease in the enzyme-treated platelets (p less than 0.05). In the presence of 0.3 mg/ml ristocetin, added vWF (2.9-14.5 micrograms/ml) caused a small but significant decrease in control platelet EPM, but caused no significant decrease in the enzyme-treated platelets. These findings suggested that the GP-Ib carrying negative charge decreased by binding of vWF might facilitate a mutual approach of the GP-Ib molecules and bridge formation by vWF between different platelets.
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PMID:Neutralization of the local negative charge carried by glycoprotein (GP)-Ib in ristocetin-induced platelet agglutination. 623 31

To better define the role of carbohydrate in the structure and ristocetin cofactor activity of von Willebrand factor, we have removed up to 83% of total hexose by sequential treatment of the molecule with endo-beta-N-acetyl-glucosaminidase F (endo F), neuraminidase, and beta-galactosidase. Endo F alone removed 69% of total hexose and D-galactose, and 71% of sialic acid. However, there was no discernible loss of large multimers and the ristocetin cofactor activity was decreased by only 11%. The reduced von Willebrand factor subunit migrated more rapidly in polyacrylamide gels containing SDS, consistent with a 10% decrease of molecular mass. All multimers of unreduced carbohydrate-modified von Willebrand factor migrated more rapidly in SDS-agarose, but the triplet pattern of individual multimers was unchanged. This alteration in multimer migration rate did not resemble alterations found so far in von Willebrand disease variants. Further treatment of von Willebrand factor with neuraminidase and beta-galactosidase reduced the D-galactose to 15% and ristocetin cofactor activity to 57%. A similar decrease in ristocetin cofactor activity was seen if von Willebrand factor was treated only with neuraminidase and beta-galactosidase. In contrast, treating von Willebrand factor with neuraminidase and beta-galactosidase in the presence of protease inhibitors (20 mM benzamidine, 20 U/ml aprotonin, 15 micrograms/ml leupeptin) resulted in a comparable removal of carbohydrate with no change in ristocetin cofactor activity. Moreover, the multimeric structure remained intact in spite of 80% removal of D-galactose. This suggested that carbohydrate was protecting von Willebrand factor against traces of one or more protease contaminants. Evidence in support of this hypothesis was obtained by exposing von Willebrand factor to plasmin after pretreatment with neuraminidase alone or with neuraminidase and beta-galactosidase. A loss of large multimers was observed from von Willebrand factor that had been pretreated with neuraminidase, but this was even greater if pretreatment was also with beta-galactosidase. In contrast, the multimeric structure of von Willebrand factor with intact carbohydrate was not affected by plasmin under similar conditions. These studies suggest that carbohydrate protects von Willebrand factor from disaggregation occurring secondarily to proteolytic attack but does not play a direct role in maintaining its multimeric structure or ristocetin cofactor activity.
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PMID:Carbohydrate moiety of von Willebrand factor is not necessary for maintaining multimeric structure and ristocetin cofactor activity but protects from proteolytic degradation. 623 76

A new, relatively simple technique has been developed in order to study the multimers of factor VIII/von Willebrand factor (VIII/vWF). It involves electrophoresis on SDS agarose gels and electrophoretic transfer (electroblotting) of the separated protein bands onto nitrocellulose membranes, to which they are non-covalently bound. VIII/vWF multimers are then detected by 125I-labelled antibodies to VIII/vWF, and autoradiography. Optimum electrophoretic transfer occurred at 0.5 A, for 18 h, on 0.8% agarose gels, thus enabling detection of the multimeric profile of VIII/vWF in 5 microliters of normal plasma. The multimeric profile for haemophilia A patients was identical to that for normal plasma. In plasma from patients with von Willebrand's disease (vWd), various patterns were seen, with a preponderance of smaller multimers in type II (atypical) vWd, similar to those seen in cryosupernatant. Heterogeneity within a particular type of vWd was also evident. Investigation of commercial factor VIII concentrates showed the presence of 'doublets' of VIII/vWF. Unlike other reported techniques, the rapid transfer and fixing of the protein bands to the nitrocellulose, minimizes loss of resolution, and handling of the paper is easier. It is possible to cut a sample electrophoresis strip into several areas, for incubation with different antibodies. Preliminary experiments also suggest that double antibody techniques are possible, or even removal of a first radiolabelled antibody by low pH, and then incubation of the separated proteins with a second, unrelated antibody.
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PMID:An electroblotting technique for the detection of factor VIII/von Willebrand factor multimers in plasma. 640 25

The nature of sugar chain of factor VIII/von Willebrand factor in plasma of normal subjects and patients with von Willebrand's disease (vWd) was examined by crossed affinoimmunoelectrophoresis using anti-human factor VIII rabbit serum, with inserted Ricinus communis agglutinin-120 (RCA-120) agarose layer (RCA - CIE). Molecular weights of factor VIII-related antigen (VIIIR:Ag) were estimated by SDS polyacrylamide gel electrophoresis - crossed affinoimmunoelectrophoresis (SDS PAGE - RCA - CIE). VIIIR:Ag, in normal plasma and in classical form of vWd, showed two precipitin peaks on RCA - CIE. The slower moving component of VIIIR:Ag with molecular weights over 3 x 10(6) daltons from normal subjects and patients with classical form of vWd showed a high affinity for RCA-120. The faster moving component of VIIIR:Ag below 3 x 10(6) daltons from the above-mentioned subjects and patients with a variant form (Type IIA) showed a very weak affinity for RCA-120. These results suggested that all of VIIIR:Ag in these variant cases may have a deficiency of galactose residues reactive with RCA, in addition to an incomplete polymerization of VIIIR:Ag, similar to that of the faster moving component of normal subjects.
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PMID:Heterogeneity of sugar composition of factor VIII/von Willebrand factor in von Willebrand's disease: analysis by crossed affinoimmunoelectrophoresis using lectin (ricinus communis agglutinin-120). 640 53

Platelet-type von Willebrand's disease is a recently described autosomal dominant bleeding disorder characterized by decreased ristocetin cofactor activity, lack of the higher molecular weight von Willebrand Factor (vWF) multimers on SDS agarose gel electrophoresis, increased platelet aggregation with low concentrations of ristocetin, and increased ristocetin-induced binding of normal vWF to patient platelets. In this report the authors describe a 17-month-old male with Platelet-type von Willebrand's disease, inherited from the paternal side of his family, who developed an inhibitor specific to Factor VIII:C. The patient's plasma inhibited normal plasma VIII:C and partially purified VIII:C; it did not appear directed against normal VIIIR:Ag or ristocetin cofactor. This antibody is therefore similar to inhibitors that develop in some transfused hemophilia A patients. Since low VIII:C, VIII:CAg, and VIII:C/VIIIR:Ag ratio were encountered in his mother, it is likely that this patient has inherited hemophilia A in addition to Platelet-type von Willebrand's disease.
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PMID:Development of an inhibitor specific to factor VIII: coagulant activity in a patient with platelet-type von Willebrand's disease. 641 54

The von Willebrand factor antigen (factor VIII-related antigen, VIIIR:Ag) multimer pattern has been analysed by SDS-agarose electrophoresis of plasmas from 116 patients (47 families) with von Willebrand's disease. In addition to previously recognized patterns, a subclassification was established between plasmas that had a type Ia pattern (VIIIR:Ag multimer pattern like that of normal plasma) and those that had a type Ib pattern in which there was a relative reduction in the concentration of the larger VIIIR:Ag multimers even though all multimeric forms were present. The different patterns were consistent within families and were inherited by autosomal dominant transmission. Von Willebrand's disease heterogeneity was apparent in the distribution of these plasmas: type Ia, 43 patients in 18 families; type Ib, 39 patients in 15 families; type II, 22 patients in 10 families, one of which was further classified as type IIB, one of which was type IIC, and three were IIA. Seven patients with severe von Willebrand's disease were also studied. In general, the interpretation of SDS-agarose multimer patterns corresponded to those previously obtained by crossed immunoelectrophoresis, but the former technique was more sensitive and could identify differences that were not apparent by crossed immunoelectrophoresis.
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PMID:Von Willebrand factor multimer patterns in von Willebrand's disease. 641 88


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