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PubMed1986

A new case of high-molecular-weight kininogen inherited deficiency.

A preoperative hemostasis study discovered a prolonged activated partial thromboplastin time in a 23-year-old Portuguese Caucasian woman without personal or past family history of hemorrhage or thrombosis. This was corrected by pooled plasma that excluded circulating anticoagulant. Activated partial thromboplastin time was prolonged whatever the activator, particularly ellagic acid, and was not corrected by prolonged kaolin incubation. Levels of factors VIII and XII were normal; factor XI and prekallikrein levels were either moderately low or normal according to activators and defective reagents used. High-molecular-weight kininogen (HMWK) level assessed by coagulation and immunological method was virtually nil. Fibrinolysis activity was normal before and after venous occlusion. The programmed operation was performed without any particular preparation and no complication arose. Family investigation found heterozygous HMWK deficiency in the proposita's father and three of her siblings.

Adult↗
PubMed1995

Different evolutionary histories of kringle and protease domains in serine proteases: a typical example of domain evolution.

With the aim of elucidating the evolutionary processes of the kringle and protease domains in serine proteases which are involved with the system of blood coagulation and fibrinolysis, we constructed phylogenetic trees for the kringle and protease domains, separately, by use of amino acid sequence data. The phylogenetic trees constructed clearly showed that the topologies were different between the kringle and protease domains. Because both domains are coded by single peptides of serine proteases, this strongly suggests that the kringle and protease domains must have undergone different evolutionary processes. Thus, these observations imply that serine proteases evolve in a way such that each domain is a unit of evolution, exemplifying a typical mode of domain evolution. A possible relationship between the domain evolution and the exon shuffling theory is also discussed from the viewpoint of gene evolution.

Amino Acid Sequence↗
PubMed1986

Human factor XIa cleaves fibrinogen: effects on structure and function.

Factor XIa, the enzymatic form of the factor XI zymogen, is generated as a result of factor XII-dependent surface activation in plasma. Factor XIa degrades high molecular weight kininogen, its cofactor for activation (which binds factor XIa to the surface), as well as cleaves and activates coagulation factor IX. In this report, we present evidence that factor XIa can also cleave fibrinogen and decrease the thrombin-catalyzed formation of the fibrin clot. Furthermore, the products of factor XIa-digested fibrinogen markedly inhibited the rate of polymerization of fibrin monomers. Factor XIa initially cleaved the A alpha-chain of fibrinogen and subsequently degraded the B beta-chain. However, the cleavage sites on both chains were distinct from those susceptible to thrombin. The gamma-chain was degraded only after prolonged incubation with factor XIa. Furthermore, the profile of fibrinogen proteolysis by factor XIa was distinctly different from that of plasmin-catalyzed fibrinogenolysis. Unlike plasmin, factor XIa was not able to cleave the NH2-terminus of the B beta-chain of fibrinogen. Moreover, factor XIa, unlike plasmin, failed to hydrolyze fibrin. Further study of the proteolytic digests of fibrinogen produced by factor XIa may give additional insight into the mechanism of polymerization of this protein.

Biopolymers↗
PubMed1981

Contact activation of factor XI.

Factor XI is a circulating trace plasma protein composed of two similar or identical chains of about 80 000 daltons which upon activation undergo proteolytic cleavage. Recently, we have shown that trypsin activation leads to an active factor XI (factor XIa) which, on reduction, yields three chains of 46 000, 37 000 and 26 000 daltons. Herein, we re-evaluate the effect of contact activation of factor XI at an activating surface both in normal human plasma and in a mixture of purified factors XI, XII, and high molecular weight kininogen (HMWK). Mixtures were analysed by coagulant activity and by reduced sodium dodecyl sulphate polyacrylamide gel electrophoresis using [125I]factor XI. In the purified system, fully activated factor XI on reduction yielded chains of 46 000, 37 000 and 23 000 daltons. In contrast, factor XI activated by surface contact in plasma yielded on reduction only chains of 46 000 and 37 000 daltons in addition to some uncleaved 80 000 chain. We propose that factor XIa containing only 46 000 and 37 000 chains be designated factor XIa alpha, and that factor XIa containing the third chain of 23 000 daltons be designated factor XI a beta. Sequential elution of contact activated plasma factor XI revealed that factor XIa was attached to the glass surface through the 46 000 dalton chain.

Autoradiography↗
PubMed1979

Coagulation studies in extremely premature infants.

Evidence of developmental evolution of coagulation can be seen when the studies of 10 thriving extremely premature (EPT) infants are compared to normal full-term (FT) infants. The prothrombin time, partial thromboplastin time, and thrombin time all became shorter with increasing gestational age. Fibrinogen levels and platelet counts appear to be comparable to term infant and adult levels. Fibrin degradation products (FDP) of 10 micrograms/ml or less were found in the thriving EPT infants. When compared to healthy full-term infants, there is a definite gestational dependency of anti-thrombin III levels. Factors II and VII appear to be related to intrauterine maturation after the age of viability (24 wk), but factor VII-X complex does not. The contact factors XI, XII, high molecular weight kininogen (Fitzgerald factor), and prekallikrein (Fletcher factor) are all markedly decreased in thriving EPT infants. The mean factor V level is lower than that found in FT infants. This study confirms a gestational age dependency of factor VIII activity. The ratio of factor VIII antigen to factor VIII clotting activity is increased (2.8 vs 1.01 in FT and adults). Thriving small for gestational age (SGA) infants had coagulation studies which were not statistically different from those of thriving EPT infants. The coagulation changes which occurred in severely ill EPT were mainly in the factors which decrease during intravascular coagulation (factors I, V, and VIII). The present study suggests that because of the high antigen to activity ratio seen in thriving EPT infants, a dysfunctional or fetal factor VIII may have been produced. However, the further elevation of this ratio in the severely ill EPT infants is in keeping with a pathologic proteolysis or increased endothelial release of factor VIII antigen.

Blood Coagulation Factors↗
PubMed1961

Hageman factor.

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Blood Coagulation Factors↗
PubMed1990

[Activated prothrombin complex preparations for the treatment of anticoagulant hemophilia. Preparation--method of operation--supply possibility].

The mechanism of the bypass activity of prothrombin complex preparatives for treatment of haemophiliacs with circulating anticoagulants remains unclear up to now. The following parameters had been tested with preparatives produced in a different manner (absorption by DEAE-Sephadex A 50, Molselekt A 50, tricalcium phosphate or aluminium hydroxide): Coagulation factors II, VII, IX, X and XII, activated factors VIIa and Xa as well as the FEIB activity. The bypass activity is strongly correlated to the factor VIIa content of the preparatives, however. These results agree with the statements by HEDNER and KISIEL, which had used a factor VII a concentrate for treatment of haemophilia complicated by circulating anticoagulants with success. According to farther investigations factor VII is correlated with the lipid content of the starting plasma. This knowledge is important for optimizing the production procedure of prothrombin complex preparatives with bypassing activity.

Absorption↗
PubMed1977

[Direct action of extracorporeal circulation on platelets and coagulation factors].

Concerning a study carried out in 250 patients, the authors confirm the classical notions concerning the fall in platelets, fibrinogenesis, factor II, XII AT3 and plasminogen during ECC. A more precise study of platelet levels shows important variations depending on the patients, whereas the length of time of ECC, the degree of importance of aspiration the first minutes of ECC, appear to be aggravating factors. There is no correlation between the type and the length of the circuit. Furthermore, from the morphological standpoint, thrombocytic changes are also noted. The same can be said of platelet function. In the last part of the work, the authors studied the causes of platelet consumption and their prevention. On the whole, and in practice, consumption of coagulation factors during ECC remains a little disturbing. It is, however, worth continuing to study their prevention.

Blood Cell Count↗