Studies on the structural abnormality of fibrinogen Paris I.

The structural properties of an inherited fibrinogen abnormality designated fibrinogen Paris I were investigated. Dodecyl sulfate gel electrophoresis of unreduced samples revealed no discernible differences in molecular weight from normal; this implied that in fibrinogen Paris I, the normal fibrinogen architecture of six covalently linked chains per molecule is preserved. Examination of dithiothreitol reduced samples before and after treatment with Reptilase or thrombin revealed that the Aalpha- and Bbeta-chains could release the A and B peptides, respectively. A mutant chain (mol wt 52,500, termed gammaParis I) which replaces a large proportion of gamma-chains (mol wt 49,400) was shown, like normal gamma-chains, to lack thrombin- and Reptilase-sensitive sites. The gamma-chains and alpha-chains of Paris I fibrin underwent Factor XIIIa-catalyzed cross-linking slowly; this behavior was not attributable to an intrinsic abnormality of these chains themselves but rather to the inhibitory effect of the mutant gammaParis I chains on this process. Results of DEAE-cellulose gradient elution chromatography of Paris I fibrinogen preparations revealed the presence of small amounts of normal fibrinogen molecules and also indicated that the gammaParis I chains possessed structural overlap with gamma-chains. Unlike gamma-chains however, the gammaParis I chains did not incorporate dansylcadaverine in the prescence of Factor XIIIa, nor, as previously reported, did they undergo cross-linking. The observations indicate that the amine acceptor site found in the COOH-terminal region of the gamma-chain is either not present on the gammaParis I chain or is unavailable for cross-linking. Further support for localization of the abnormality in the COOH-terminal region of the molecule was obtained from the observation that during plasmic hydrolysis of Paris I fibrinogen, at least one unique form of core Fragment D (DParis I) was evolved, whereas Fragment E did not differ from normal.

The mechanism of activation of human prothrombin by an activator isolated from Dispholidus typus venom.

Purified human prothrombin was activated, both in the absence and in the presence of thrombin inhibitors (diisopropylfluorophosphate or hirudin), by a coagulant principle isolated from Dispholidus typus venom. The process of activation was monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In the absence of thrombin inhibitor, prolonged incubation of prothrombin with the purified venom yielded thrombin, fragment 1 (F 1) and fragment 2 (F 2). In the presence of diisopropylfluorophosphate, which in the experimental conditions used inhibited only partially the thrombin generated activity, products obtained upon activation of prothrombin by venom were F 1 and a two-chain, disulfide-bridged protein of 58 000 daltons called meizothrombin (des F 1). In the presence of hirudin, which fully inhibited thrombin generated activity, prothrombin activation by the venom did not liberate any fragment, but prothrombin was converted to a derivative composed of two disulfide-bridged polypeptide chains of 48 000 and 37 000 daltons, called meizothrombin. These results are similar to those reported by others when studying the process of prothrombin activation by Echis carinatus venom and allow to conclude that Dispholidus typus venom cleaves a bond linking the A and B chains of thrombin, converting prothrombin into meizothrombin. This enzyme is then responsible for the cleavage of the bond linking F 1 and F 2 and the bond linking F2 the A chain of thrombin.

New treatments of von Willebrand disease: plasma derived von Willebrand factor concentrates.

During the past 10 years the quality of plasma derived virus inactivated products containing von Willebrand factor (vWF) has improved and the ratios of ristocetin cofactor activity (vWF:RCo) to von Willebrand factor antigen (vWF:Ag) have increased. There are, however, considerable variations in AHF-vWF products with ranges from 0.25 to 1.4 unit of vWF:RCo for each unit of vWF:Ag, and 0.5 to 5.3 units of vWF:RCo for each factor VIIIC (FVIIIC) unit. The availability of a vWF product depleted of FVIII has allowed pharmacokinetic studies of the vWF protein. There have been no dose response studies, dosage regimens remain empirical and are still, except in rare instances, based on FVIIIC dosage. Current concentrates are as effective as cryoprecipitate in the management of patients with vWD non responsive to DDAVP. These concentrates should be preferred to cryoprecipitate which carries a risk of virus transmission.

A survey of the effectiveness of prothrombin complex concentrates in controlling hemorrhage in patients with hemophilia and anti-Factor VIII antibodies.

The treatment of patients with hemophilia A and anti-Factor VIII antibodies is difficult. Between July 1977 and June 1978, a survey was carried out by an ad hoc working party of the subcommittee on Factor IX concentrates of the International Committee on Thrombosis and Hemostasis to assess the effectiveness of Prothrombin Complex Concentrates in controlling hemorrhage in these patients. The results are presented in this paper and, although subjective, support the view that these concentrates are not as effective in patients with inhibitors as Factor VIII concentrates are in patients without inhibitors.

Haemostatic disorders and respiratory distress in the newborn.

Coagulation and fibrinolysis studies were performed on 64 newborns; 16 premature infants with hyaline membrane disease (HMD), 17 newborns with other forms of respiratory distress syndrome (RDS) (8 of them were premature), 31 healthy newborns (11 of them were premature). All the babies were studied once in the first 48 hours of life. There was no significant difference between sick and healthy babies for 5 parameters; platelet count, factor VIII, fibrinogen, fibrin(ogen) degradation products, euglobulin lysis time. Factor II, VII and X were low in all infants, and premature infants had significantly lower levels compared to full term newborns. Factor V, plasminogen, alpha 2 macroglobulin (alpha 2M) and antithrombin III (AT III) levels were significantly lower in sick infants. Except for AT III, these deficiencies were not related to prematurity. No significant difference was found between HMD and other RDS. Of the 33 sick infants, 5 developed laboratory findings consistent with disseminated intravascular coagulation (DIC). The results indicate that the coagulation and fibrinolytic abnormalities reported are not specific to HMD.

Antithrombin III concentrates.

The general characteristics of antithrombin III (AT III) concentrates available in the United States are described in this article. The effectiveness of AT III concentrates in the prevention and treatment of thrombotic episodes in patients with hereditary AT III deficiency are summarized, and the use of this product in various conditions with acquired AT III deficiency are reported.

Rapid methods for isolation of human plasma fibronectin.

Simplified procedures have been developed for isolation of human plasma fibronectin by affinity chromatography on gelatin-agarose. In one method, fibronectin is eluted with 3 M urea, and this reagent is quickly removed by adsorbing the protein onto heparin-agarose, followed by 0.4 M NaCl elution. In a shorter process, fibronectin is eluted from gelatin-agarose simply by decreasing the buffer pH below 6. After lyophilization the purified protein can be readily dissolved in water. The fraction not adsorbed to gelatin can be used to purify other proteins, including factor VIII whose procoagulant activity is quantitatively recovered.

Safety monitoring and epidemiological surveillance of blood transfusion in the United States.

Safety monitoring and epidemiological surveillance of blood transfusion in the United States is complex and involves government agencies and independent organizations. Several systems of control are in place nationwide to ensure that blood, blood components, and plasma derivatives meet prescribed standards. Control and surveillance of drugs that are biologics, which include human blood, blood components and plasma derivatives, are exercised by the Food and Drug Administration. Epidemiological surveillance involves several agencies and organizations that constitute a network capable of rapidly detecting unusual adverse events.