Mechanism of the anticoagulant action of phospholipase A purified from Trimeresurus mucrosquamatus (Formosan habu) snake venom.
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W Jy
Publications and source records attributed to W Jy.
Increase of intraplatelet free calcium ion during extracorporeal circulation with a hollow fiber oxygenator: arterial filter and dynamics of platelet thrombosis on oxygenator and filter in a pig model.
Intraplatelet free calcium (IPFC) ions provide a common pathway for platelet activation leading to thrombosis and embolization. IPFC levels were determined by chlorotetracycline fluorometry during extracorporeal circulation (ECC) with systemic heparin in eight Yorkshire pigs (weighing 30-40 kg; 3 control and 5 ECC); the ratio of slow phase organelle calcium sequestration to fast phase platelet-membrane binding is an index of free calcium. During 3 hr of ECC with a hollow fiber oxygenator (HFO) (Bentley CM-50) and AF (Bentley 1025), seven blood samples were collected 5 min before and during ECC. The platelet deposition (CPM/microCi) on HFO (PDHFO) was simultaneously measured with In-111-labeled autologous platelets (300-400 microCi) and a Geiger probe detector at -5, 0, 5, 30, 45, 60, 120, and 180 min. During ECC, IPFC and HFO thrombus increase significantly (p less than 0.05) at 45 min with respect to control IPFC values of 0.4 +/- 0.1, suggesting direct participation of calcium activated platelets in thrombosis on HFO. The decline of IPFC is due to extrusion and sequestration by dense granules, and decline in HFO thrombus is due to embolization. On the other hand, the embolus in the arterial filter was trapped in a linear fashion, with a consistent increase with time of ECC.
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A higher blood flow window of reduced thrombogenicity and acceptable fragmentation in a hollow fiber hemodialyzer.
The effect of pulsatile blood flow on platelet thrombogenicity and platelet fragmentation (PF) in a hollow fiber hemodialyzer (HFD) was quantified with 111In labeled platelets and 125I labeled fibrinogen; 150 ml of blood was collected from Beagle dogs, Yorkshire pigs, and a human volunteer (non-smoker). Platelets were labeled with 111In tropolone (300 microCi) and fibrinogen was labeled with 125I. Sham dialysis (SHD) was performed with 120 HFDs (0.9 meter2) at 37 degrees C, with flow-rates of 150, 250, 500, and 950 ml/min.; after SHD, the washed HD radioactivity was measured with an ionization chamber. PF was measured by flow cytometry with GP IIb-IIIa murine monoclonal antibody. Platelet deposition decreased significantly for 3 species at higher flow; fibrinogen deposition (10-12%, 55-65 mg/m2), was not affected by flow. Adherent platelet thrombus decreased from (8.2 +/- 3.4) to (3.1 +/- 1.0) with human blood as flow rate increased from 150 to 950 ml/min; platelet thrombus level also decreased significantly (p < 0.005) from (20.3 +/- 6.2) to (4.5 +/- 1.9) with canine blood. Higher values were obtained for canine than human and porcine platelets. Platelet fragmentation, on the other hand, increased from 2.1-2.2% to 10.2-11.3% with increase of flow. Like platelets, deposition of canine fibrinogen was slightly higher than that of pig and human. The studies of adherent thrombus and platelet fragmentation identified an important flow-window of reduced thrombogenicity and acceptable fragmentation, encouraging extracorporeal circulation at higher blood flow.
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