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Restenosis is a serious therapeutic problem after percutaneous transluminal angioplasty (PTA). Strategies for the prevention of late restenosis include the use of antiaggregatory and anticoagulant drugs, aggressive lipid-lowering, intravascular radiation and others. As some of these therapeutic options are not without side effects it is important to identify patients with an increased risk to develop restenosis. Major clinically recognizable risk factors for restenosis are advanced disease stage and female gender. Elevated plasma levels of fibrinogen, Lp(a), CRP, and migration-inducing activity appear to indicate an unfavorable clinical outcome, and so does post-interventional increase of vWF and PAI-1 antigen. For peripheral arterial disease, only one study has addressed the influence of homocysteine levels upon the restenosis rate after PTA. Although homocysteine levels were elevated in50% of patients at entry, they were not associated with a higher restenosis rate. Currently the available data allow a rough approximation of a patient's individual risk.

The formation of prostacyclin (PGI2) and thromboxane A2 and the release of beta-thromboglobulin (beta-TG) at the site of platelet-vessel wall interaction, i.e. in blood emerging from a standardized injury of the microvasculature made to determine bleeding time, was studied in patients with end-stage chronic renal failure undergoing regular haemodialysis and in normal subjects. In the uraemic patients, levels of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were 1.3-fold to 6.3-fold higher than the corresponding values in the control subjects indicating an increased PGI2 formation in chronic uraemia. Formation of thromboxane B2 (TxB2) at the site of plug formation in vivo and during whole blood clotting in vitro was similar in the uraemic subjects and in the normals excluding a major defect in platelet prostaglandin metabolism in chronic renal failure. Significantly smaller amounts of beta-TG were found in blood obtained from the site of vascular injury as well as after in vitro blood clotting in patients with chronic renal failure indicating an impairment of the alpha-granule release in chronic uraemia. We therefore conclude that the haemorrhagic diathesis commonly seen in patients with chronic renal failure is--at least partially--due to an acquired defect of the platelet alpha-granule release and an increased generation of PGI2 in the microvasculature.

An assay system has been developed that allows consecutive quantification of tissue-type plasminogen activator (t-PA) activity and t-PA antigen in the same plasma sample. In the first step t-PA is bound to an immobilized IgM monoclonal anti-t-PA antibody and functional activity of bound t-PA is quantified by its plasminogen-activating activity. In the second step the amount of bound t-PA antigen is determined by using a different peroxidase-labeled monoclonal anti-t-PA antibody. In this combined assay system t-PA functional activity was found to depend not only on the amount of t-PA antigen but also on the amount of plasminogen activator inhibitor (PAI), whereas in the t-PA antigen assay PAI did not affect the results. In plasma samples obtained from normal controls t-PA activity was detected only in post-venous occlusion plasma (3.7 +/- 2.5 IU/ml), whereas 2.7 +/- 0.5 ng/ml t-PA antigen was found before and 12.6 +/- 4.4 ng/ml after venous occlusion. Using this combined assay system to study plasma samples from patients who did not respond to venous occlusion with shortening of the euglobulin clot lysis time (ECLT), it was possible not only to confirm that in none of these patients could t-PA activity be detected in the postocclusion plasma samples but also to subdivide that group of patients into a group of about 39% not reacting with normal t-PA antigen release to venous occlusion and into a second group of about 61% that reacted with normal t-PA antigen release.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibodies to tissue type plasminogen activator (t-PA), urokinase (u-PA) and alpha-2-antiplasmin were obtained by immunizing Balb C mice with the respective purified antigens and fusion of spleen cells with mouse myeloma cells (NSO). The selected monoclonal antibodies reacted exclusively with the respective antigens used for immunization. 3 out of 7 monoclonal antibodies directed against t-PA inhibited plasminogen activation by t-PA and 6 of 7 interfered with the fibrin potentiating effect. Only one out of 5 monoclonal antibodies directed against u-PA inhibited plasminogen activation by u-PA. None of the monoclonal antibodies directed against t-PA or u-PA inhibited the cleavage of low molecular weight paranitroanilide substrates by the respective plasminogen activators. Likewise, the 3 monoclonal antibodies to alpha-2-antiplasmin did not functionally inhibit alpha-2-antiplasmin. The selected monoclonal antibodies were used to develop sensitive test systems for the respective antigens. The lower detection limit for determination of t-PA was found to be 0.5 ng/ml, for determination of u-PA 0.05 ng/ml, and for determination of alpha-2-antiplasmin 5 ng/ml.

Efficacy of percutaneous transluminal angioplasty (PTA) is limited by restenosis occurring in a large proportion of patients. Smooth muscle cell (SMC) migration is a major pathomechanism of restenosis. We studied SMC migration inducing activity of plasma from patients with peripheral arterial occlusive disease (PAOD) undergoing PTA.SMC migration was determined in a two-dimensional assay system after addition of 1/25 plasma dilutions. Mean increase in migration area was 65.5 +/- 33.8% in normal controls and 67.7 +/- 53.2% in patients with PAOD. 6 hours after PTA, plasmatic migration inducing activity was largely unchanged. In 19/30 patients with restenosis (6 months after PTA) migration promoting activity (82.7 +/- 60.0) was significantly higher than in 11/30 patients with patent vessels (41.8 +/- 21.0; p = 0.03). No correlation of clinical risk factors with outcome was observed. A weak correlation was found between plasmatic migration promoting activity and levels of epidermal growth factor and transforming growth factor-beta.The capacity of human plasma to stimulate SMC migration in tissue culture can be used to assess the risk for restenosis after PTA in patients with PAOD.