摘要:

Highly purified bovine factor VIII prepared according to our technique and having a specific activity of 500 U/mg protein has been studied. The chemical analysis of the preparation revealed it to be composed of amino acids, lipids (8–10%) and carbohydrates (7 %). The lipid moiety can be removed by chromatography. Different mechanisms of inactivation of bovine factor VIII and the possible molecular changes induced by the inactivating agents were studied. EDTA and EGTA provoke a weakening of the bonds linking the structural elements of the molecule, which allows for the separation of two different components of the molecule by gel filtration. Upon treatment with thrombin, the carbohydrate content of bovine factor VIII decreases without any apparent degradation of the protein moiety of the molecule. The fact that precipitating and neutralizing antisera against factor VIII were obtained, shows that the molecules modified by EDTA and thrombin still have the antigenic properties of factor VIII. The inhibitor developed by hemophiliacs transfused with human factor VIII is bound to bovine factor VIII, forming a complex which is stable upon agarose gel filtration. Immunological studies of the purified complex reveal that it is composed of bovine factor VIII and human γ-globulin. Bovine factor VIII in the complex retains some antigenic determinants which bind rabbit anti-serum against bovine factor VIII, as shown by neutralization of the antiserum and by precipitation studi

ISSN:1424-8832    

DOI:10.1159/000214113

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The aim of this work was to discover to what extent cigarette smoking and oral contraceptives, either separately or in association, are responsible for platelet adhesiveness changes in humans. Platelet adhesiveness has been measured in 77 subjects, smokers and nonsmokers. 47 of these subjects were women both using and not using oral contraceptives. Cigarette smoking significantly increases platelet adhesiveness both in men and women. On the contrary, if no distinction is made in the smoking habits of female volunteers and they are only divided into two groups according to the use or nonuse of oral contraceptives, no significant change in platelet adhesiveness occurs following intake of oral contraceptives.

ISSN:1424-8832    

DOI:10.1159/000214114

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Chlorpromazine is known to inhibit platelet function in vitro. The intramuscular injection of 50 mg to human volunteers caused only minor changes in platelet function. There was a small, but significant, reduction in the platelet count, the second phase of the double-wave of adenosine diphosphate-induced aggregation and the rate of 5-hydroxytryptamine-induced aggregation. Patients on high doses of chlorpromazine had no demonstrable abnormality of platelet function. This suggests that chlorpromazine, despite its inhibitory effect on platelet function in vitro, is unlikely to interfere with either haemostasis or thrombogenesis after its administration to man.

ISSN:1424-8832    

DOI:10.1159/000214115

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Acetylsalicylic acid and phenylbutazone increased the bleeding significantly from standardized wounds in dogs defibrinogenated with Defibrase. Administration of dipyridamole and Xylocain® had no effect. The results were the same in dogs treated with warfarin sodium. The results demonstrate the value of using laboratory animals with an induced coagulopathy when establishing the effect on the haemostasis exerted by drugs known in vitro to interfere with platelet functions. Acetylsalicylic acid and dipyridamole did not alter the activity of the K-vitamin-dependent coagulation factors, factors V, VIII, platelet count or fibrinogen concentration

ISSN:1424-8832    

DOI:10.1159/000214116

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Although anti-platelet serum is frequently used to produce thrombocytopenia, the mechanism of how platelets are removed from the circulation is poorly understood. In vitro studies indicated that anti-platelet serum caused platelet aggregation, whereas normal rabbit serum did not. The aggregation was dose related; at the lower dose, aggregated platelets were shown to deaggregate and platelets released from the aggregates responded normally to ADP but not to collagen. In mice whose platelets were previously labeled with Na235SO4, anti-platelet serum caused an increase in the amount of 35S mucopolysaccharides (MPS) recovered from the kidneys. No increase in radioactivity was found in the lungs, livers, or spleens of similarly treated mice. The data suggest that platelet specific anti-serum causes platelets to aggregate leading to ADP (and consequently 35S-MPS) release; the accumulation of 35S in kidneys may be due to removal of MPS and/or platelets from the circulation.

ISSN:1424-8832    

DOI:10.1159/000214117

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

In the PRP of anaphylactic rats, ADP, collagen and thrombin induced platelet aggregation was considerably reduced. Reduced aggregability could be transferred to normal platelets by suspending them in the PPP of anaphylactic animals and the impaired aggregation of platelets from animals undergoing anaphylaxis could be restored by exchanging their plasma for that of normal controls. Ellagíc acid, a known activator of factor XII, produced similar alterations as obtained in anaphylactic shock. It is suggested that the inhibition of platelet aggregation is due to the anaphylactic activation of factor XII and this mechanism may be of importance in rat anaphylaxis

ISSN:1424-8832    

DOI:10.1159/000214118

出版商:S. Karger AG    

年代:1976

数据来源: Karger