Search PubMed⌕ Search

Biomedical subjects

D L Aronson

Publications and source records attributed to D L Aronson.

68 records · Page 4Linked to original sources
PubMed1975

Activation of human prothrombin by a procoagulant fraction from the venom of Echis carinatus. Identification of a high molecular weight intermediate with thrombin activity.

In the presence of a procoagulant fraction (Echis carinatus procoagulant) isolated from the venom of the saw-scaled viper Echis carinatus sochureki, purified human prothrombin (P1) is completely converted to thrombin. The first step is the removal of an NH2-terminal peptide (F1) representing approximately one-third of the prothrombin molecule. The remaining peptide (P2) is then cleaved by the action of E.c. procoagulant to yield a two-chain, disulfide-bridged protein (P'2) which has the same molecular weight as P2. P'2 has enzymic (thrombin) activity, as evidence by incorporation of radiolabeled diisopropylphosphate into its heavy chain (TB), hydrolysis of p-toluenesulfonylarginine methyl ester, and clotting of fibrinogen. Relative to thrombin, its esterolytic activity greatly exceeds its clot-promoting activity. Examination of the polypeptide chains obtained by reducing P'2 has shown that its larger chain (TB) is indistinguishable from the heavy chain of thrombin. Its other chain (F2TA) consists of the light chain (TA) of thrombin bound by peptide linkage to the protion of the prothrombin molecule which had been adjacent to F1. Removal of this portion (F2) is catalyzed by thrombin (and, evidently, by P'2), but not by the E.c. procoagulant. When F2 is removed from P'2, the remaining two-chian protein is indistinguishable from thrombin by any of the criteria applied--molecular weight, subunit chain composition, or enzymic activity. Polyacrylamide gel electrophoresis was carried out in sodium dodecyl sulfate before and after disulfide reduction of samples generated in the presence and in the absence of diisopropylphosphorofluoridate, which inhibits thrombin but not the E.c. procoagulant. Such experiments showed that thrombin (and probably P'2), as well as E.c. procoagulant, catalyzes the release of F1. Furthermore, thrombin brings about the cleavage of F1 to yield a two-chain, disulfidebridged protein (F'1). These observations, particularly those made in the course of characterizine P'2, have led to the conclusion that cleavage of the peptide bond connecting the TA and TB portions of the prothrombin molecule (or its derivatives) produces a serine active center and, hence, a molecule possessing thrombin activity. This cleavage is catalyzed by the E.c. procoagulant but not by thrombon itself.

Animals↗
PubMed1975

Potentially thrombogenic materials in factor IX concentrates.

Factor XI concentrates manufactured from human plasma and intended for therapeutic infsuion in man have been suspected for some time of being potentially thrombogenic. In the current studies, assays were carried out in vitro and in vivo for potentially thrombognic materials. It was possible to rank the various materials tested according to the amount of thromboninic material detected. For concentrates not containing heparin, there was substantial agreement between the in vivo and in vitro assays, with a coefficient of correlation of 0.77. There was no correlation between the assays for thrombogenicity and the antithrombin III content. We conclude that many presently availabel concentrates of Factor IX contain substantial amounts of potentially thrombogenic enzymes, and that this fact must be considered in arriving at the decision whether or not to use them therapeutically.

Animals↗
PubMedDate not supplied

Plasma derivatives and viral hepatitis.

Plasma derivatives can be separated into those with either a low or a high risk of transmitting viral hepatitis. Low-risk products, with few exceptions, will remain low-risk irrespective of the plasma from which they are manufactured because they are heated at 60 degrees C for 10 hours (Albumin, Plasma Protein Fraction) or because they contain protective antibodies (Immune Globulin). This would appear to be the case not only for hepatitis B but also for non-A, non-B hepatitis. The risk of hepatitis B associated with plasma derivatives is reduced but not eliminated by HBsAg screening of donors. Further decreasing the risk of hepatitis B associated with AHF or Factor IX lots, as well as newer products like AT-III, alpha-1 antitrypsin, Fibronectin, C-1 Inactivator, and Factor XIII, may be accomplished either by the combination of stabilization and heating or by assuring that these products contain an excess of anti-HBS. For highly-purified products with little residual immunoglobulin it may be necessary to add anti-HBs. The addition of antibodies against non-A, non-B hepatitis agents when they are identified, could prevent transmission of both forms of viral hepatitis by plasma derivatives. Methods to stabilize and heat high-risk plasma derivatives to inactivate hepatitis viruses have the potential to remove both hepatitis B and non-A, non-B hepatitis infectivity.

Animals↗