The Ratio MDA/MDAa as a New Index of Platelet Hyperactivity

Abstract

Since 1979, malonyldialdehyde (MDA) is considered a sensitive index of platelet hyperactivity. Stimulators of phospholipase A2 are used in the procedure of MDA production in order to obtain the final quantity (MDAa) which corresponds to the total amount of arachi-donic acid present; without stimulation the production of MDA is minimal in non-activated platelets (MDA non-activated). Therefore, the more the MDA/MDAa ratio approaches unity, the more activated are the thrombocytes. We utilized for the first time this new index for the investigation of hyperactive platelets, and we studied 56 persons (17 patients with thrombotic or thrombophilic disease as group A, 17 normals as group B and 22 diabetics without ketoacidosis as group C). We proved that the new index (MDA/MDAa) can be used to detect persons with functionally hyperactive platelets because large differences are found between the mean values of normals and the values of patients with established thrombotic disease, at a high confidence limit (x ± 3 SD covering 99% of the samples). Comparing the sensitivity of this new index with the other three methods used for the detection of hyperactive platelets [ratio of circulating platelet aggregates (CPA), aggregation with ADP, spontaneous aggregation] in groups B and C we found that only the ratio MDA/MDAa was able to reveal that (a) the two groups B and C are not identical (a statistical conclusion after comparison with the other methods) and (b) there were 5 diabetics in group C who had more hyperactive platelets than the others (these patients were not detected by any other method).

In vivo Platelet Hyperreactivity, another Risk Factor for Patients under Continuous Ambulatory Peritoneal Dialysis

“…MDA was measured by the thiobarbituric acid method [10], and the MDA/MDA;l index was established as described by Makris et al [8] using N-ethylmaleimide as activator.…”

“…Thromboembolic manifestations in patients under continuous ambulatory peritoneal dialysis (CAPD), although recognized, have been less well documented [7]. The present study was undertaken to evaluate ex vivo the functional state of platelets from CAPD patients, through its aggregatory responses to physiological agonists such as epinephrine and collagen and the ratio of malondialdehyde (MDA) production under basal and stimulated conditions (MDA/MDAa) [8],…”

Effect of lacidipine and nifedipine GITS on platelet function in patients with essential hypertension

“…The test was repeated twice and the values averaged in each case. Measurement of platelet malondialdehyde production: Malondialdehyde was measured by the thiobarbituric acid methods, 15,16 using N-ethylmaleimide (Sigma Chemical Co) as activator, at the end of placebo and active therapy. Venous blood was collected from the antecubital vein and mixed with 3.8% sodium citrate solution.…”

“…The ratio MDA-basal (isotonic saline)/MDA-activated (NEM) was calculated as described by Makris et al 16 …”

Thiobarbituric Acid Reactive Substances as a Biomarker for Coronary Heart Disease

“…More importantly, MDA is also a by-product of cyclooxygenase activity in platelets 8) ; therefore, the measurement of MDA in serum may lead to an over-estimation due to the formation of MDA formation ex-vivo, as platelet activation is required for the formation of serum 9) . When using serum as the sample matrix for analysis of oxidative stress, it is worth considering the issue of specificity for this particular reason.…”