1. A radioimmunoassay has been developed for measuring endothelin-like immunoreactivity in human plasma using an antibody raised against endothelin-1 which also cross-reacts with big endothelin-1 and endothelin-2 but not endothelin-3. 2. The sensitivity of the assay was 1 fmol/tube with inter- and intra-assay coefficients of variation of 13% and 9%, respectively. Cross-reactivity with endothelin-3 and non-endothelin peptides was less than 1%. 3. Endothelin-like immunoreactivity was present in the plasma of hypertensive patients (n = 25) at a concentration of 5.7 +/- 0.5 pmol/l (mean +/- SEM), which was not significantly different from that of age-matched control subjects (5.1 +/- 0.5 pmol/l). At these levels, endothelin-1 is unlikely to function as a circulating hormone. 4. Within the normotensive group, the concentration of endothelin-like immunoreactivity in plasma was positively correlated with mean arterial blood pressure, but in hypertensive patients it showed a significant negative correlation.
Descartes's claim that the eternal truths were freely created by God is fraught with interpretive difficulties. The main arguments in the literature are classified as concerning the ontological status or the modalities of possibility and necessity of the eternal truths. The views of the principal defenders of the Creation Doctrine – Robert Desgabets, Pierre Sylvain Régis, and Antoine Le Grand are contrasted with those of Nicolas Malebranche. In clarifying the theological, ontological, and logical terms of the debate we can see that what was at stake was the objectivity and certainty of the truths of mathematics and physics. I conclude by suggesting that this issue might fruitfully be used to clarify the disparate discussions in the contemporary literature.
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