Dialysis with prostacyclin (Epoprostenol, PGI2) alone prevents platelet activation and endothelial cell stimulation but not the elevation of fibrinopeptide A (FPA), a sensitive marker of fibrin generation. The generation of FPA may explain why some patients develop clot in the dialysis circuit during PGI2-only dialysis. In combination with heparin, PGI2 augments the anticoagulant effect of the heparin as well as providing platelet protection.
S ummary By the use of light and electron microscopy a quantitative investigation has been made of plastid membrane formation in the primary leaves of bean plants, during germination and growth in the dark. From 4 to 14 days of dark growth there was an eleven‐fold increase in cell number and a twenty‐six‐fold increase in plastid number per leaf. Formation of plastid envelope membrane between 6 and 14 days of dark growth amounted to 98 cm 2 of membrane per leaf while the corresponding formation of internal plastid membrane was 272 cm 2 per leaf. This internal plastid membrane appears to be formed, at least during the early stages of leaf growth, by the invagination of the inner envelope membrane. When a substantial amount of the thylakoid membrane has accumulated in the plastid a condensation process takes place to give the pro‐lamellar body, which is a structure composed of branching membrane tubules. Calculations based on the dimensions of these tubules have established that 1 μ 3 of prolamellar body contains about 44 μ 2 of membrane. Dark‐grown leaves have been found to contain all of the enzymes of the photosynthetic carbon cycle. The course of development, during dark growth, has been determined for the activities of eight enzymes of the photosynthetic carbon cycle and for two enzymes of the cytoplasm.
In 20 hemodialysis patients using mainly flat plate dialyzers, we have conducted a controlled randomized crossover trial of three dose regimens of a low molecular weight heparin (LMWH), "Fragmin" (Kabi 2165), in comparison with a standard dose regimen of commercial unfractionated heparin (UFH) that had previously been shown to provide effective anticoagulation. The aim of the present study was to find the lowest dosage regimen of the LMWH which would be as effective as the standard UFH regimen. The UFH regimen comprised a prime with heparinized saline, an initial intravenous bolus of 5,000 international units (IU) and an infusion of 1,500 IU/h. The three LMWH regimens comprised a LMWH-saline prime, an infusion of 750 anti-factor Xa (aXa) U/h and three different bolus doses: 1) LMWH-low: 3,000 aXa U. 2) LMWH-medium: 4,000 aXa U. 3) LMWH-high: 5,000 aXa U. With the UFH regimen, plasma heparin levels of around 1.0 IU/ml were maintained during the heparin infusion, declining to 0.71 IU/ml an hour after the infusion was terminated. The LMWH-medium regimen produced very similar plasma aXa levels. The LMWH-high regimen also produced similar plasma aXa levels: therefore, it had no advantage over the LMWH-medium regimen. The LMWH-low regimen produced significantly lower levels than the other regimens during the heparin infusion (0.81-0.85 aXa U/ml, p less than 0.025). Dialysis proceeded uneventfully at all times and plasma levels of fibrinopeptide A (FPA) were suppressed well with all 4 regimens (2.77-5.74 pmol/ml) but tended to rise after the infusion was switched off (5.52-8.45 pmol/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
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