Generation of annexin V-positive platelets and shedding of microparticles with stimulus-dependent procoagulant activity during storage of platelets at 4 degrees C.

BACKGROUND: The ability of propyl gallate to activate platelet factor 3 has been determined through the activated partial thromboplastin time, but its effect on phosphatidylserine has not been established. STUDY DESIGN AND METHODS: A novel platelet activator, propyl gallate, was introduced to a study of platelets stored at 4 degrees C. The effects of storage on platelet coagulation activity, on phosphatidylserine, and on the shedding of activated and activable membrane particles (microparticles) were examined by activated plasma clotting time, and the effect on annexin V binding was examined by gated flow cytometry. The ratios of annexin V binding and microparticle shedding in stored platelet samples were compared with those in fresh platelets stimulated with propyl gallate. RESULTS: Microparticle shedding by stored platelets compensated for the diminished procoagulant potential of intact platelets (shown as the total propyl gallate-dependent platelet factor 3 activity), which did not change during prolonged (20-day) storage, but levels of phosphatidylserine confined to microparticles increased dramatically as platelet counts fell. Both annexin V binding and microparticle shedding increased spontaneously with storage and artificially with propyl gallate stimulation. However, at the same level of annexin V binding, stored platelets shed more microparticles than did fresh platelets stimulated with propyl gallate. CONCLUSION: Propyl gallate induces platelet procoagulant activity and annexin V binding. Stored platelets differ from fresh platelets in a lower reactivity to propyl gallate activation and a higher rate of microparticle shedding.

Supraventricular tachycardia with edema, ascites, and hydrops in fetal sheep.

Continuous supraventricular tachycardia was induced in 13 fetal sheep for 72 to 216 hours. The PaO2 decreased from 18.1 +/- 1.2 (SEM) to 15.4 +/- 0.9 mm Hg and the PaCO2 increased from 41.5 +/- 1.2 (SEM) to 46.0 +/- 1.0 (SEM) mm Hg with pacing. The hematocrit, total protein, albumin, serum [Na+] and [K+], and osmolality remained unchanged throughout the study. All study fetuses showed signs of ascites (mean = 88 +/- 67.5 [SD] ml), and one was grossly hydropic. Six fetuses, all of which had greater than or equal to 50 ml of ascites, died as the results of pacing. Gross pathologic findings in 13 fetuses included: cardiomegaly in seven, cyanotic myocardium in two, hepatomegaly in seven, pulmonary congestion in two, generalized edema in three, and massive edema (hydrops) in one. None of these conditions was found in the 14 control animals. There was no correlation of the severity of effects upon the fetus and the induced heart rate, the duration of tachycardia, or the site of implantation of the pacemaker. The conclusion was that organomegaly, generalized edema, and hydrops fetalis were the direct result of supraventricular tachycardia in utero; the exact mechanism of production and the reasons for the variable manifestations of tachycardia remain unclear.

Addition of triglyceride to serum for use in quality control and reference.

We describe a simple method in which a water-soluble mixture of triocatanoin and a surfactant, "Triton X-114," are used in preparing solutions of triglycerides (triacylglycerols) in either human serum, solutions of albumin, or water. Analytical recovery added triglyceride was quantitative by two methods. The addition did not affect results of analyses for 18 other commonly measured constitutents of serum. When the triglyceride was added to either lipid-depleted human serum or bovine serum albumin solution and lyophilized, subsequent solutions were clear. The triglyceride/protein preparation was stable in lyophilized form for a year and in reconstituted serum for five days at 5 degrees C. Aquenous solutions appear to be stable indefinitely at room temperature.