Background: Mast cells are prevalent in the shoulder of unstable atheromas; cardiac mast cells secrete proteases capable of activating matrix metalloproteinases. Histamine is essential in the inflammatory cascade of the unstable plaque. Ascorbate depletion has been correlated with histaminemia which has been shown to impair endothelial‐dependent vasodilation. This study evaluates whether oxidative stress as measured by isoprostanes (PGF2α) coupled with an inflammatory state characterized by histaminemia predisposes patients to acute coronary syndrome (ACS). Methods: Whole blood histamine, serum vitamin C, and serum PGF2α levels were drawn on 50 patients with ACS as determined by standard diagnostic criteria, 50 patients with stable coronary artery disease (SCAD), and 50 age and sex matched normal controls (C). Results: Data were analyzed by stepwise discriminant and Spearman's rank correlation coefficient. A significant relationship exists between histamine and PGF2α. As PGF2α rises above 60 pg/mL, an increase in histamine occurs in both the ACS and SCAD groups. A significant inverse relationship exists between ascorbate and histamine in the ACS versus C groups (P < 0.01) and the SCAD versus C groups (P < 0.01). Conclusion: Histamine and isoprostane levels increase in SCAD and ACS patients. Mast cell activation and lipid oxidation generated during atherosclerosis manifest this inflammatory response. Accelerated isoprostane formation and depleted ascorbate paired with histaminemia is active in CAD and predispose patients to acute coronary syndrome. Blood histamine alone may be a better risk factor for coronary events, and a better prognostic indicator than CRP even when combined with lipid indexes.

Analysis of 437 human blood samples has shown that when the plasma-reduced ascorbic acid level falls below 1 mg/100 ml, the whole blood histamine level increases exponentially as the ascorbic acid level decreases. When the ascorbic acid level falls below 0.7 mg/100 ml, there is a highly significant increase in the blood histamine level. Oral administration of ascorbic acid (1 g daily for 3 days) to 11 selected volunteers resulted in a reduction of the blood histamine level in every instance.

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AND J. CHURCHMAN, B.Sc.THE passage of amino-acids across the placenta has been studied for many years. Morel and Mouriquand (1 9 13), using the Van Slyke (1 9 12) method of amino-acid estimation, found no difference between human foetal and maternal whole blood amino-acid levels, and were thus able to postulate simple diffusion of amino-acids across the placenta. Rabinovitch (1914), using the same method, found the foetal to exceed the maternal levels.Morse (1917) studied 17 pregnant women, and found a higher level of presumed amino-acid nitrogen in plasma from the umbilical cord than in the maternal plasma. His mean values, using the gasometric nitrous acid method of Van Slyke (1912) which estimates all primary aliphatic amines, were 6 . 4 mg./100 ml. in the maternal and 8 -7 mg./100 ml. in the foetal plasma. Hellmuth (1924) and Plass and Matthew (1925), using the Fohn (1922) method, also found higher foetal than maternal plasma levels, suggesting either a diffusion gradient from foetus to mother, or an active process involved in the transfer of amino-acids from mother to foetus. Luck and Engle (1929) disputed this evidence, and revived the simple diffusion theory.Settlement of this question awaited the development by Hamilton and Van Slyke (1943) of an analytical method which was more specific for amino-acids. Christensen and Streicher (1948), using this manometric ninhydrin method, showed that the amino-acid level of foetal plasma was considerably higher than that of the mother, foetal/maternal ratios being 5/1 for the J . biol. Chem., 149, 255. Chem., 150, 231.C. (1951): Human Biol., 23, 61. 88,230.Paris, 75, 643. Brit. Emp., 58, 701. Hopk. Hosp., 36, 393. Gynaec.

Studies of the electrolyte concentrations of uterine fluid samples from spayed rats, after injection of ovarian hormones, showed a much higher potassium concentration after treatment with oestrogen (42\m=.\3 m -e q u i v . / 1 . ) than with progesterone (20\m=.\8 m -e q u i v . / 1 . ) .