Clotting Activity Of Platelets Research Articles

Omega-3 fatty acids and antioxidants in edible wild plants.

Human beings evolved on a diet that was balanced in the omega-6 and omega-3 polyunsaturated fatty acids (PUFA), and was high in antioxidants. Edible wild plants provide alpha-linolenic acid (ALA) and higher amounts of vitamin E and vitamin C than cultivated plants. In addition to the antioxidant vitamins, edible wild plants are rich in phenols and other compounds that increase their antioxidant capacity. It is therefore important to systematically analyze the total antioxidant capacity of wild plants and promote their commercialization in both developed and developing countries. The diets of Western countries have contained increasingly larger amounts of linoleic acid (LA), which has been promoted for its cholesterol-lowering effect. It is now recognized that dietary LA favors oxidative modification of low density lipoprotein (LDL) cholesterol and increases platelet response to aggregation. In contrast, ALA intake is associated with inhibitory effects on the clotting activity of platelets, on their response to thrombin, and on the regulation of arachidonic acid (AA) metabolism. In clinical studies, ALA contributed to lowering of blood pressure, and a prospective epidemiological study showed that ALA is inversely related to the risk of coronary heart disease in men. Dietary amounts of LA as well as the ratio of LA to ALA appear to be important for the metabolism of ALA to longer-chain omega-3 PUFAs. Relatively large reserves of LA in body fat. as are found in vegans or in the diet of omnivores in Western societies, would tend to slow down the formation of long-chain omega-3 fatty acids from ALA. Therefore, the role of ALA in human nutrition becomes important in terms of long-term dietary intake. One advantage of the consumption of ALA over omega-3 fatty acids from fish is that the problem of insufficient vitamin E intake does not exist with high intake of ALA from plant sources.

Influence of vitamin E administration on platelet functions in hormonal contraceptive users

Platelet functions (aggregation, clotting activity), platelet lipid biosynthesis, sterol composition and phospholipid fatty acids were studied in relation to plasma lipids and fatty acids as well as dietary habits at day 5 and 21 of the menstrual cycle in 30 women having used hormonal contraceptive for several years. The women were studied again on day 21 of the second cycle after they had taken for two months 200 mg vitamin E per day in addition to the contraceptive. At day 21 (after 3 weeks of hormonal contraceptive) as compared to day 5, there was a significant increase in the clotting activity of platelets and the response to ADP-induced aggregation concomitant with a decrease in plasma vitamin E. After vitamin E administration, platelet activity at day 21 was markedly decreased, being similar to the activity at day 5, with a significant increase in the level of vitamin E in plasma and platelets. The high response of platelets to aggregation in women using contraceptives does not seem to be associated with the intake of saturated fat but rather with that of 18:2. The aggregation to throwbin was mostly related to lanosterol biosynthesis and the aggregation to ADP to platelet cholesterol, but not to plasma lipids or apoproteins. The present pilot study suggests that the platelet hyperactivity of long-term hormonal contraceptive users might be dependent upon a low level of platelet α-tocopherol which can be rapidly overcome by giving a supplement of vitamin E.

Nutrients, platelet function and composition in nine groups of French and British farmers

In 260 male farmers (40–45 years) divided into 9 groups from different areas in France and Britain, coagulation, platelet aggregation, lipemia, fatty acids from plasma lipids and platelet phospholipids were determined in relation to the food intake evaluated by recall, weighing and chemical analysis of the diet. The clotting activity of platelets and their response to thrombin aggregation was significantly correlated on an individual basis with the intake of saturated fatty acids both in subsamples as well as in the whole study. Serum cholesterol was also significantly correlated with saturated fats but only on a group basis or on the totality of the study. Calcium, linolenic acid and alcohol in the diet were inversely related to certain platelet functions. Linoleic acid was inversely related to serum cholesterol and triglycerides. Dietary saturated fats were associated, (i) with an increase in the platelet phospholipids not in saturated fatty acids but in 20: (n-9), known to promote platelet aggregation to thrombin, (ii) with a decrease in platelet cholesterol, also apparently regulating platelet functions. The present studies indicate that dietary saturated fats, calcium (hard water) and alcohol, influence platelet behaviour in a way strictly parallel to their known effect on coronary heart disease.

Influence of long-term diet modification on platelet function and composition in Moselle farmers

Platelet function and composition, lipemia, and dietary habits were evaluated yearly in 98 male farmers from Moselle (East of France) before and after decreasing, in half of them, dietary saturated fats from 16.2% to 9.9% of calories (P/S from 0.32 to 0.97). One year after these dietary changes, cholesterol and triglycerides decreased by approximately 10%, platelet aggregation to thrombin by 81%, and their clotting activity by 30%. However, ADP aggregation was enhanced by 54%. At 2 yr the P/S was decreased to 0.7 and diet also modified in controls, with 18:2 being increased mostly in one group (P/S = 0.81 ) and 18:3 in another (P/S = 0.59). In both groups, the main platelet function tests were significantly depressed 1 yr later. Considering the whole study, the intake of saturated fat was mostly correlated (group and individual) with platelet aggregation to thrombin, platelet clotting activity, and 20:3 (n-9) in plasma and platelet lipids.

Protective effects of dietary calcium and magnesium on platelet function and atherosclerosis in rabbits fed saturated fat

Male rabbits were fed for 6 months a purified diet rich in fat (45% of calories), mostly saturated (butter) containing per 100 g either 354 mg of calcium and 46 mg of magnesium (group I), 948 mg of calcium and 46 mg of magnesium (group II), or 354 mg of calcium and 356 mg of magnesium (group III). In group II, fed the additional calcium, significant ( P < 0.001) changes were observed; i.e. prolongation of clotting time (platelet clotting activity), decrease in platelet aggregation to thrombin, and in the concentration of the plasma total cholesterol, with a less significant ( P < 0.05) decrease in plasma triglycerides. A significant ( P < 0.01) decrease in the ratio monoemes/ 18:2 in the plasma cholesterol esters but not in the plasma or platelet phospholipids was also found in these rabbits. In relation to their lower activity, platelets from group II exhibited a significant increase in 22:4n-6 (phospholipids) and in the ratio cholesterol/phospholipids, both significantly correlated with the platelet function tests. In this same group, the excretion of fecal lipids and saturated fatty acid 18:0 was increased by 4.3-fold and 7.6-fold, respectively. The severity of atherosclerosis and the accumulation of cholesterol in the aorta were significantly lower in group II, while the plasma level of calcium was similar to that of group I. In group III, fed additional magnesium, results were similar to those of group II, but less significant. It seems that calcium (and magnesium) markedly decreased the atherogenicity of saturated fats by promoting their fecal excretion, thus decreasing their untoward effects on serum lipids and platelet functions. These results may be related to the known protective effect of hard water on coronary heart disease.

Inhibitory effect of alcohol on platelet functions of rats fed saturated fats

The consumption of alcohol in man appears to be inversely related to the incidence of.coronary heart disease (CHD) (1). It seems that this beneficial effect of alcohol is not related to a lowering of blood lipids since alcohol is known to be hypertriglyceridemic (2). Studies in French farmers (3), confirmed in more extensive investigations in French and British farmers (4) have shown that platelet clotting activity and platelet aggregation induced by thrombin, but mostly by ADP, epinephrine and collagen, were inversely related to the alcohol intake. Platelets appear to be closely associated with CW being involved not only in thrombosis but also in early atherosclerotic lesions (5). In our studies in farmers, we have shown that platelet functions were the only blood parameter significantly correlated with the intake of sa' turated fat (4), the environmental factor the most closely assotiiated with CHD (6). In the present study in rats fed saturated or polyunsaturated fats, we have observed that alcohol, both in vivo and in vitro, inhibits certain platelet functions, chiefly in animals fed a saturated diet.

Platelet phospholipid in stroke

A study of platelet phospholipids in patients with stroke has been undertaken comparatively with patients without predisposition to thrombosis. An increase in the phospholipid/protein ratio in platelets was observed in patients with acute cerebrovascular accident. A significant increase of palmitoleic acid is observed in platelet phospholipids of these patients; it is accompanied by a decrease of linoleic acid. These modifications are reflected in plasma where linoleic acid is greatly diminished but where an important increase of palmitic acid is noted besides palmitoleic acid. A possible relation between higher clotting activity of platelets and those modifications in their phospholipids is discussed.

Platelet Functions in Relation to Dietary Fats in Farmers from two Regions of France

To determine whether the long-term feeding of dietary fats affect platelet functions in man, platelet aggregation (to thrombin ADP, collagen, epinephrine) and clotting activity of platelet-rich plasma (PRP), platelet-poor plasma and of washed platelets were studied in a mobile-laboratory in 44 healthy male farmers (40--45 years) from two French regions Var and Moselle, in relation to lipemia, glycemia, dietary nutriments, and platelet phospholipid composition. In the Moselle subjects, the platelet clotting activity of PRP and of washed platelets, the platelet aggregation to thrombin and ADP, were highly significantly (p less than 0.001) increased as compared to those of Var, but not the plasma cholesterol, which was identical in the two regions. In Moselle, the intake of total calories, total lipids and saturated fats was higher than in the Var. However, it was only with the saturated fat intake (mostly stearic acid) that the platelet clotting activity (p less than 0.01) and the platelet aggregation (p less than 0.001) were highly significantly correlated. The platelet clotting activity was also significantly (p less than 0.001) correlated with the fatty acid composition of the platelet phospholipid fractions phosphatidyl serine + phosphatidyl inositol.

Platelet Factor 3 Activity in Washed Platelets

SummaryPlatelets collected with an EDTA solution and simply washed in an incomplete Tyrode’s presented clotting times in the recalcification (man and rat) and the Stypven (rat) tests that were practically identical to those of the PRP when slow speed centrifugation was used (800 G in man, 1000 G in rat). This was demonstrated, in 6 pools of 5 rats each and in 6 men, by comparing the clotting activity of the citrated platelet-rich plasma to that of the platelets washed and resuspended in the citrated platelet-poor plasma, for platelet counts ranging from 1 × 105 to 10 × 105/mm3. In contrast, centrifugation of platelets at 3000 G markedly affected these clotting activities, as was shown in an additional study comprising 6 pools of 3 rats.Finally, the clotting activity of platelets totally disrupted by sonication appears to be identical quantitatively in both man and rats to that of the total phospholipids extracted from these platelets and separated from the other lipids by thin-layer chromatography and resuspended in plasma by sonication.

Thromboplastin as a Clotting Factor

SummaryThe clotting activity of platelets can be sensitively measured by the prothrombin consumption time using normal platelet-depleted plasma as the assay medium. Such plasma when clotted in a glass tube shows no demonstrable consumption of prothrombin but as platelets are added in increasing amounts, the utilization of prothrombin is increased in an approximately straight-line proportion. Similar results are obtained when certain agents such as the Bell-Alton reagent, Inosithin and hemolysate, all of which have a high concentration of phospholipids and are employed in the thromboplastin generation test as platelet substitutes, were assayed by the prothrombin consumption test. Both Inosithin and the Bell-Alton reagent fail to cause significant consumption of prothrombin when the plasma is clotted in silicone-coated tubes, thereby demonstrating the need of a contact factor which is probably thrombin. Since Inosithin which is of plant origin functions efficiently as a platelet substitute in the thromboplastin generation test and in the prothrombin consumption assay test, it presents the probability that the clotting factor in platelets could be of exogenous origin. Its release from platelets requires the action of thrombin.