The platelet MDA and plasma TXB2 formation was studied in normal subjects and in patients with obliterative arteriosclerosis of the lower limbs. The increase in platelet MDA and plasma TXB2 formation ...could be found in these patients. It is concluded that these factors as well as the decrease in plasma cAMP level previously reported may play decisive role in the pathogenesis of occlusive arterial disease.
In 7 healthy volunteers, the effect of a single i.v. injection of 52 mg (7,500 IU) of an unfractionated heparin (UFH) and of 52.5 mg (5,000 anti XaU) of a low molecular weight heparin (LMWH) on ...coagulation parameters and platelet function has been studied. Thrombin-induced platelet aggregation was inhibited after the injection of both heparins. There was no significant change of ADP or collagen-induced aggregation after LMWH of UFH. Platelet adhesion to bovine extracellular matrix was not inhibited by UFH but was significantly reduced after addition in vitro and ex vivo after administration of LMWH. Further investigation should establish the time course of LMWH effects on platelet adhesion. A long duration of this effect could be partially correlated with the antithrombotic effects of LMWH.
We investigated the comparative antithrombotic properties of LW 10082, acetylasalicylic acid (Aspisol), low molecular weight heparin (LMWH, CY 216) and sodium heparin using laser-induced thrombosis ...model. The animal model which has been used is well suited to observe platelet reactions to damaged endothelial cells and also to evaluate the effect of drugs on the formation of platelet thrombi. The rat mesenteric venules with a diameter of 20-30 microns were injured by well defined argon laser lesion. The number of laser injuries which were needed to induce a thrombus intermittently occluded the vessel was counted to quantitate the results. LW 10082 was injected sc 2 h prior to testing. The minimal effective dose of LW 10082 which significantly inhibited thrombus formation was 5 mg/kg. The antithrombotic effect of Aspisol has been investigated after its oral application at doses of 1.5 and 10 mg/kg 2 h before studying the antithrombotic effect. The minimal effective dose for Aspisol was 10 mg/kg. The LMWH has been injected into the rat tail vein in doses of 1, 0.2 and 0.1 mg/kg 30 min before testing. 0.1 mg/kg did not have any antithrombotic effect. The minimal effective dose of the sodium heparin which significantly inhibited thrombus formation was 20 U/kg measured 30 min after its iv injection. The combination of minimal effective dose of LW 10082 and LMWH had a significant additive effect. There was a slight but not significant additive effect between LW 10082, Aspisol and heparin sodium. Our results suggest that combinations of LW 10082 with LMWH may provide a new approach to more effective prophylaxis and treatment of venous or arterial thrombosis.
The mode of action by which heparins exert their antithrombotic effect is not fully understood. Antithrombotic action persists much longer than the inhibition of even sensitive coagulation ...parameters. We therefore have investigated antithrombotic and thrombolytic activity of two low molecular weight heparins Fraxiparin (Sanofi) and Clexane (Rhone-Poulenc) in a rat model of laser-induced thrombosis. The antithrombotic effect was measured by the number of laser injuries required to induce a defined venous thrombus which was at least as broad and as high as the vessel diameter. Thrombolytic activity of low molecular weight heparins was investigated by measuring the time from venous occlusion to recanalisation of the vessel. Fraxiparin in minimal dose of 0.001 mg/kg after iv injection showed antithrombotic effect in the laser thrombosis model. After single iv injection of this dose antithrombotic effect of Fraxiparin lasted longer than 6 h but less than 8 h. In higher dose of 0.01 mg/kg after single iv injection thrombolytic activity of Fraxiparin was observed. Also Clexane showed dose dependent antithrombotic and thrombolytic activity in this model. In dose of 0.005 mg/kg after single iv injection of Clexane significant inhibition of thrombus formation was observed. This antithrombotic effect lasted longer than 6 h but less than 8 h. In dose of 0.05 mg/kg after iv injection Clexane showed significant thrombolytic activity. In conclusion, further investigations are needed to optimize prophylactic and therapeutic use of low molecular heparins.
Radiologic contrast media may influence processes of hemostasis resulting in increased thrombotic or bleeding tendency. A number of clinical case reports suggest that the use of nonionic contrast ...media is associated with thrombotic complications. In vitro studies have indicated that nonionic contrast media may induce generation of thrombin in blood whereas ionic contrast agents do not show such an effect. Not much is known about the effects of contrast media on the coagulation and fibrinolytic systems in vivo. The aim of this study was to evaluate the systemic effects of markers for activation of fibrinolysis with a nonionic contrast medium (Iopromid/Ultravist-300/Schering AG) and ionic contrast medium (Uropolinum, Polfa) in 82 patients undergoing angiography. We measured tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor (PAI), using COA-SET, t-PA and COA-TEST PAI (Chromogenix). Fibrinogen concentration and euglobulin lysis time (ELT) were also estimated. Both contrast agents caused a significant decrease in fibrinogen concentrations. A marked difference was seen for PAI activity. A statistically significant increase was seen in the Iopromid group and no statistically significant rise was seen in the Uropolinum group. t-PA activity remained virtually unchanged in both groups. ELT has been significantly prolonged in patients who received Iopromid but not in those who received Uropolinum. It is likely that nonionic contrast medium could release PAI from platelets and endothelial cells. The changes in fibrinolysis may result from endothelial cell dysfunction.
Circulating blood monocytes, which are a source of foam cells contribute to the vascular lesions. Von Willebrand factor (vWF) is an adhesive multimeric glycoprotein that is synthesized only by ...endothelial cells and megakaryocytes. In the present study we assessed the ability of human platelets to secrete vWF after incubation with blood monocytes in vitro. Monocytes derived from blood of healthy adults were cultured and next incubated with washed platelets. von Willebrand factor antigen (vWF:Ag) was measured in the supernatant by Laurell immunoelectrophoresis. The study showed that Triton X-100 treated platelets released 82-112% of vWF:Ag. The levels of vWF:Ag in the supernatant with untreated platelets and incubated with monocytes without LPS were respectively 36-48% and 45-72%. After incubation washed platelets with LPS stimulated monocytes a significant decrease in vWF:Ag level was observed (7-11%).
In this work, the main aim was to determine the effect of Mg addition on the crystallization kinetics and microstructure of Zn-10Al-1Cu alloy. The effectiveness of magnesium addition was detected on ...the basis of microstructure morphology investigations and changes occurring in the cooling curves of the investigated alloys. To describe the phenomena that occurred in the material during solidification under various conditions caused by a change in the chemical composition as a result of the appliance of modifiers, it was decided to use methods of thermal derivative analysis, allowing to effectively and accurately describe the crystallization kinetics of the tested materials. The scientific goal of the presented work was examination of the impact of magnesium addition and effect of the crystallization kinetics on the examined alloys. Determining the relationship between the changes in the derivative curve and the related microstructure, the influence of modifiers addition was analysed. The addition of Mg caused a shift of the solidification temperature values of phases and eutectics and monotectoid transformation (???) to lower temperature values, as well as the change of the morphology of the occurring eutectic ??+?.
Multifunctional materials have become an important research subject in recent years. Zinc oxide nanoparticles (ZnO NP) deposited on iron oxide (Fe
3
O
4
) allow to obtain material with photocatalytic ...and magnetic properties. The mass share of Fe
3
O
4
in the composite was 30%. Saturation magnetization for this sample was about 9.5 emu/g. The use of magnetic material allows to recover the photocatalyst after the photodegradation process and reuse it. The possibility of recovery of Fe
3
O
4
nanoparticles with a magnet was estimated at 94.80%, while the recovery of Fe
3
O
4
/ZnO achieved 83.91%. The effects of the type of dyes (Methylene Blue, Methyl Orange, Quinoline Yellow, Eriochromic Black T and Trypanic Blue) on their photodegradation efficiency in terms of molar mass of the dye, the solvent in which the processes were carried out and the type of dye charge were investigated. The photocatalytic material showed higher photodegradation activity of dyes while increasing their molar mass. ZnO NPs deposited on Fe
3
O
4
presented 95.61% photocatalytic efficiency against Trypan Blue and 63.02% against Methylene Blue. Increasing the surface area of the catalyst to 39 m
2
/g and the presence of micro-, meso- and macropores had a positive effect on the sorption process of dyes, especially those of larger sizes, allowing their degradation in the photodegradation process.
PDF
