The problem of thrombosis associated with the use of synthetic materials implanted in the blood stream continues to be serious.
The surface properties of biomedical implants have been widely studied and many hypothesis proposed concerning to their antithrombogenicity on the basis of experimental results.
In this paper, the antithrombogenicity of pharmacologically active surfaces and physicochemically innert surfaces are discussed. This article also refers to the development of useful novel methods for the analysis of the interaction between blood components and polymer surfaces.

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The peripheral circulatory disturbances caused by long term use of vibratory instruments, characterized typically by the development of Raynaud's phenomenon on the fingers have been recognized as occupational vibration syndrome (VS).
In order to elucidate the possible mechanisms of these peripheral disturbances, we studied the molecular markers of coagulation and fibrinolysis in patients with VS.
Seventy one patients and 111 healthy persons as a control were used in this study.
The following results were obtained;
1. The Thrombin-antithrombin complex (TAT)/plasmin α₂ plasmin inhibitor complex (PIC) ratio of patients with VS was significantly higher than that of the control.
2. The TAT/PIC ratio of the Raynaud's phenomenon positive group was higher than that of the Raynaud's phenomenon negative group in the patients with VS.
3. The TAT/PIC ratio increased parallel to the severity of Raynaud's phenomenon.
4. Other parameters such as fibrinogen, TAT, fibrinopeptide A (FPA), fibrinopeptide Bβ_15-42 (FPB) and PIC of the Raynaud's phenomenon positive group were also higher than those of the Raynaud's phenomenon negative one.
These results suggest that both the activity of coagulation and fibrinolysis were elevated in the patients with VS.
Moreover, the activation markers of coagulation such as TAT were apparently more dominant than the activation markers of fibrinolysis such as PIC.
Thus from these findings it is deduced that hypercoagulability may play an important role in the development of peripheral circulatory disturbances in patients with VS.

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Prothrombin time (PT) is an established screening method for hemorrhagic disorders. Recent progress of the biochemistry of tissue factor (TF)-dependent coagulation pathway revealed that TF/factor VIIa complex activated factor IX rather than factor X. However, PT does not reflect the activity of factors IX and VIII, because of excess amount of TF reagent in the assay system. In this study, we evaluated PT using highly diluted TF reagent (Dil-PT) and its clinical application. Coexistence of magnesium with calcium ion resulted in the shortening of Dil-PT. Dil-PT prolonged in accordance with the decrease of TF reagent, and prolongation was observed in factor VIII-and factor IX-deficient plasmas similarly to the factor X-, factor V-, factor VII-and factor II-deficient plasmas. On the contrary, prolonged clotting time of factor XI-, factor XII-, high molecular weight kininogen-and plasma prekallikrein-deficient plasmas were the same as that of normal pooled plasma in the Dil-PT system. In the clinical samples, significant shortenings of Dil-PT and PT were observed in the patients with rhabdomyolysis. On the other hand, Dil-PT showed significant shortning in gestational toxicosis, but PT did not. These results suggest that Dil-PT reflect the activity of factors IX and VIII besides factors VII, X, V and II, and Dil-PT is an useful screening method that does not require specific reagents and apparatus for the detection of hypercoagulable state.

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A heterozygous dysfibrinogen, fibrinogen Kumamoto, derived from a 29-year-old woman with episodes of recurrent blurred vision accompanied by weakness of the ipsilateral lower extremity was found to have an Arg-19 to Gly substitution. Both the thrombin and ancrod times were prolonged, and fibrin monomer polymerization profiles were abnormal with a slightly prolonged lag phase and a moderately reduced amplitude. When analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis, thrombin-catalyzed cleavage of both fibrinopeptides A and B was only minimally delayed and factor XIIIa-catalyzed cross-linking of the fibrin γ-chains was obviously altered. Nevertheless, that of the fibrinogen γ-chains was identical with the normal control in the early stage of the reaction, but was substantially delayed in the later stage. These results may imply that the initial contact between two adjacent D domains of different fibrinogen molecules took place normally, but that the molecular realignment of partially cross-linked single-stranded fibrinogen oligomers to create double-strands was perturbed. In addition to these dysfunctions, decreased adsorption of thrombin to fibrin gels was observed. This finding suggests that immobilization of thrombin onto fibrin clots is incomplete, and thus thrombin action on fibrinogen and platelets in blood circulation is seemingly potentiated, accounting for the transient ischemic attacks in the patient. This type of amino acid substitution has been shown in two dysfibrinogens, Aarhus and Mannheim I, and a transient ischemia was observed in fibrinogen Aarhus I as well.

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