The effect of salicylates on the hemostatic properties of platelets in man

Acute upper-gastrointestinal hemorrhage. New observations on an old problem

In a two-year period, 289 patients with acute upper-gastrointestinal hemorrhage were evaluated. The site of hemorrhage was proven by endoscopy in more than 90% of cases. The frequency of any particular bleeding site was characterized for several subgroups and was found to correlate with: (1) the severity of the bleeding episode; (2) the iatrotropic stimulus of hemorrhage, and (3) the history of ethanol consumption. No difference was found in the frequency of ulcer and acute mucosal lesions as sites of hemorrhage between patients who consumed aspirin and those who did not. A history of symptoms of peptic ulcer correlated with the presence of an ulcer as the bleeding site. It is possible that failure to identify important patient subgroups may be partially responsible for the disagreement between previous reports.

Inhibition of arachidonic acid induced mortality in rabbits with several non-steroidal anti-inflammatory agents

The intravenous administration of arachidonic acid to rabbits is an effective in vivo model for evaluating potential anti-thrombotic drugs. Most of the non-steroidal anti-inflammatory agents (NSAIFA) inhibit this arachidonic acid induced mortality (except sodium salicylate and acetaminophen). However, there is a lack of correlation between the relative potencies from various assays (rabbit anti-thrombotic, anti-inflammatory, alalgesic, ulcerogenic and inhibition of prostaglandin synthetase evaluations). These studies imply other actions with NSAIFA than an effect solely on the prostaglandin biosynthetic pathway.

Effects of nitroblue tetrazolium and vitamin E on platelet ultrastructure, aggregation, and secretion

All agents capable of triggering the platelet release reaction also stimulate prostaglandin biosynthesis in these cells. Information concerning the endoperoxides, thromboxanes, and more stable metabolites generated by the action of cyclooxygenase and lipoxygenase on arachidonic acid has accumulated rapidly, but little is known about the preliminary steps in the cleavage and preparation of arachidonic acid for insertion into the enzymatic pathways of prostaglandin synthesis. Studies in this laboratory have shown that the combination of nitroblue tetrazolium (NBT) and vitamin E which prevents oxygenation of arachidonic acid to a free radical also blocks platelet prostaglandin biosynthesis. The present study has evaluated the influence of NBT, vitamin E, and the combination of NBT and vitamin E on the fine structure and biochemistry of platelets during incubation, and the effects of these compounds on the aggregation and secretion of platelets stimulated by collagen, thrombin, epinephrine, and ADP. Results of the study demonstrate that NBT and vitamin E, rather than injuring platelets, appear to protect them during incubation. Together NBT and vitamin E blocked aggregation by epinephrine, collagen, and thrombin, but permitted a small first wave stimulated by ADP. Both ADP and thrombin induced shape change, pseudopod formation, and limited degrees of internal contraction in vitamin E-NBT-treated platelets, whereas epinephrine and collagen failed to significantly alter discoid form. This pattern of response to aggregating agents was identical to reactions observed in platelets pretreated with aspirin and indomethacin, both potent inhibitors of platelet prostaglandin synthesis. In addition, NBT-vitamin E virtually blocked the first wave of aggregation which is not affected by aspirin and indomethacin. The findings support the concept that conversion of arachidonic acid to an activated state is an important step in prostaglandin synthesis and that electron transfer or oxidation-reduction reactions are intimately involved in the development of platelet stickiness.

Prevention of arterial thromboembolism with acetylsalicylic acid. A controlled clinical study in patients with aortic ball valves

Prevention of arterial thromboembolism with acetylsalicylic acid (ASA) was studied in 148 patients with single Starr-Edwards aortic ball-valve prostheses. These patients are suitable for such a study because they have a high incidence of arterial emboli derived mainly from thrombi formed on the valves. They were given either 1 Gm. of ASA daily or placebo in combination with anticoagulants, and were observed for 2 years. Only two emboli occurred in patients receiving ASA, none of them severe. In the placebo group 12 thromboembolic episodes were diagnosed in 10 patients, and three with cerebral emboli died; in one a subdural hematoma unrelated to the embolus was found. In addition, one fatal and the one nonfatal intracranial bleeding occurred in each group, whereas gastrointestinal complications were seen more frequently in patients taking ASA. It is concluded that ASA combined with anticoagulants offered a significantly better protection against arterial thromboembolism than did anticoagulant therapy alone.

Inhibition of cholesterol esterification in rabbit aorta by prostaglandin E2

Cholesterol esterification in the arterial wall was investigated with cell-free preparations of intima-media from control rabbits and rabbits rendered atherosclerotic by feeding a diet containing 1% cholesterol. In the presence of 2 mM ATP and 0.1 mM CoA, the major activity for esterification of [4-14C] cholesterol added in vitro was found in the 12,000 g and 105,000 g pellets. In control animals, the activity in the latter pellet was twice that in the former. After cholesterol-feeding for 6 months, the activity increased 5-fold in the 105,000 g pellet and 2-fold in the 12,000 g pellet of the atherosclerotic intima-media. Prostaglandin E2 (PGE2) in concentrations between 2 and 12 X 10(-7) M exhibited a dose-dependent inhibition of the esterifying activity in both particulate preparations. The inhibition was 97% at PGE2 concentrations greater than 1.2 X 10(-6) M in preparations from control animals. Inhibition by PGE2 in preparations from atherosclerotic rabbits was also observed. These results suggest a possible regulatory role of PGE2 in cholesterol esterification in the arterial wall.

Effect of sodium salicylate and acetylsalicylic acid on epicardial ST-segment elevation during coronary artery occlusion in dogs

The effect of sodium salicylate and acetylsalicylic acid (ASA) on myocardial ischaemic injury following acute coronary artery occlusion has been studied in thoracotomized dogs during basal conditions and during elevation of plasma free fatty acid (FFA) concentration induced by intravenous (i.v.) infusion of isoprenaline (0.075-0.15 microgram/kg/min). Ischaemic injury was measured as the sum of ST-segment elevations (sigmaST) in epicardial ECG recordings from 10-15 sites 15 min after occlusion. Both sodium salicylate and ASA (60 mg/kg) significantly reduced sigmaST both before and during isoprenaline infusion. Arterial concentrations of FFA were reduced by either drug during isoprenaline infusion, whereas in the basal state only a significant effect by sodium salicylate could be demonstrated. The reduction in epicardial ST-segment elevation during coronary occlusion could not be explained by reduced mechanical activity of the heart. It is suggested that the reduction by salicylates of myocardial ischaemic injury might be related to reduced utilization of FFA by the myocardium, although a FFA-nondependent mechanism cannot be excluded in the basal state.

Controlled trial of aspirin in cerebral ischemia

Adouble-blind trial of aspirin for the treatment of cerebral ischemia was begun in 1972 and continued for 37 months. This was accomplished despite difficulties in controlling a long-term study of a drug which has widespread availability and consumption. The study design, criteria for selection of patients, follow-up surveillance, and methods of data analysis are presented. We report only subjects without carotid surgery before randomization. Patients (178) who had carotid transient ischemic attacks (TIAs) were randomly allocated to aspirin or placebo and followed to determine the incidence of subsequent TIAs,death, cerebral infarction or retinal infarction. Analysis of the first six months of follow-up revealed a statistically significant differential in favar of aspirin when death or cerebral or retinal infarction and the occurrence of TIAs were grouped and considered together as end points. Significance in favor of aspirin treatment was mainly revealed in patients with a history of multiple TIAs and was most evident in those individuals having carotid lesions appropriate to the TIA symptoms. It cannot be inferred from this study that aspirin prevents stroke because when end points were restriced to death or cerebral or retinal infarction, there was no statistically significant differential between the aspirin and placebo treatments.

von Willebrand's disease and hemorrhagic telangiectasia: association of two complex disorders of hemostasis resulting in life-threatening hemorrhage

The clinical and laboratory findings in a patient with uncontrolled gastrointestinal bleeding secondary to combined hemostatic defects (von Willebrand's disease and hemorrhagic telangiectasia) are described. Evidence for von Willebrand's disease was found in five family members, but no other affected relative was found to have hemorrhagic telangiectasia. Complete assestivity, factor VIII antigen and von Willebrand factor levels. The patient described also was evaluated for her response to transfusion utilizing these same measurements. Previous reports of the coexistence of hemostatic defects with hereditary hemorrhagic telangiectasia are reviewed. The importance of complete hemostatic evaluation of patients with mucocutaneous bleeding is stressed in light or current knowledge of the diagnostic specificity of available laboratory tests.

Preparation and storage of platelet concentrates. II. Storage variables influencing platelet viability and function

Factors affecting the viability and function of stored platelet concentrates have been investigated in a blood component programme. It was found that platelets could be maintained for up to 72 h without bacterial contamination under the following conditions: (1) surgical skin preparation at venipuncture site; (2) blood collection in CPD or ACD anticoagulant in a closed bag system; (3) centrifugation of PRP at 3000 g for 20 min; (4) storage in Fenwal PL-146, Cutter CL-2383, or McGaw plastic bags; (5) resuspension of the platelet pellet in 70 ml residual plasma; (6) storage at 22+/-2 degrees C; and (7) constant gentle mixing throughout storage. Platelet viability as determined by recovery and survival is largely maintained, as is platelet function measured by template bleeding time. Both viability and function of concentrated platelets stored at 4 degrees C are severely compromised.

The effects of four commonly used drugs on platelet function

A number of commonly used drugs have been reportd to inter

Spontaneous hyphema associated with ingestion of aspirin and ethanol

Unilateral hyphema, hematuria, and ecchymoses developed in a previously healthy 42-year-old women after the ingestion of aspirin and ethanol. There was no evidence for ocular trauma, disease, or vascular malformation by slit-lamp examination and gonioscopy. Platelet count and coagulation tests were normal. The patient's bleeding time was prolonged and there was impaired platelet aggregation. Delayed (secondary) aggregation in response to collagen, adenosine diphosphate, and epinephrine was decreased, as was aggregation induced by thrombin and serotonin. These data indicate that the qualitative platelet defect was induced by both aspirin and ethanol. Anterior chamber hemorrhage subsided after discontinuation of aspirin and ethanol, and the hyphema subsequently resolved. Bleeding time and platelet aggregation were normal two weeks after the patient's initial presentation. A prolonged bleeding time in association with normal platelet count, prothrombin time, and partial thromboplastin time indicated a qualitative platelet defect, which is most commonly drug-induced. Defective platelet function resulted in spontaneous hyphema.

Aspirin therapy in angina pectoris: effects on platelet aggregation, exercise tolerance, and electrocardiographic manifestations of ischemia

If altered platelet function contributes to poorly perfused zones of myocardium in patients with angina pectoris, then specific antiplatelet therapy might improve cardiovascular function and exercise performance. Exercise tolerance on a bicycle ergometer, heart rate-blood pressure product, and ischemic ECG changes at exercise end-point were compared before and during oral aspirin therapy (2.4 Gm. per day for 2 weeks) in 11 normal subjecs and in 11 patients with stable angina pectoris. Platelet aggregation threshold in response to ADP and epinephrine was measured. Untreated patients had increased platelet aggregability when compared to normal subjects...

Gingival hemorrhage related to aspirin ingestion. A case report

A case report illustrating the clinical manifestations of platelet defects induced by ingestion of two aspirin tablets has been presented. The specific effects on platelets produced by aspirin ingestion have been summarized and the resultant hemostatic defect explained.

The effect of aspirin on 5-hydroxytryptamine uptake and release by human platelets

The influence of aspirin on 5-hydroxytryptamine (5-HT) uptake and storage by human blood platelets has been investigated. Uptake of 5-HT was strongly inhibited. In 30 min aspirin released 50% of the 5-HT that had been incorporated into the platelets prior to the addition of the aspirin. These results are discussed in terms of possible interference with a 5-HT membrane receptor and the impairment of 5-HT storage in the dense granules.

A standardized bioassay for platelet factor 3 released by kaolin

The test for platelet factor 3 described by Hardisty & Hutton (1975) has been modified to conform to the usual design for a parallel-line bioassay. Manchester Comparative Thromboplastin has been used as assay Standard, allowing an arbitrary unit of activity to be adopted. However, experiments suggested that the platelet activity measured was different from tissue factor activity. Platelets are tested as platelet-rich plasma diluted in a standardized mixture of plasma and fibrinogen, so that differences between the clotting factors of the test samples are eliminated, as verified by experiments on haemophiliacs and patients on anticoagulant treatment. Sonication and repeated freezing and thawing of platelet-rich plasma showed that approximately 15% of the PF3 is released by kaolin. In vivo, a single dose of 600 mg of aspirin reduced the PR3-release to half the previous value in 2 h; initial values were regained in 5-8 days.

Platelet hyperaggregability in idiopathic recurrent deep vein thrombosis

Studies of platlet function were performed in 30 patients with idiopathic recurrent venous thrombosis. Evidence of platelet hyperactivity was found in 14 patients who exhibited spontaneous platelet aggregation and in 13 patients who had evidence of circulating platelet aggregates. No other differences in clinical characteristics or coagulation parameters could be elucidated between these two subgroups. In nine patients who had 51Cr-labeled platelet survival studies, there was a good correlation between the platelet hyperactivity and shortened platelet survival. Spontaneous platelet aggregation was inhibited both in vivo and in vitro by aspirin. In addition, the circulating platelet aggregates were normalized by combination treatment with aspirin and dipyridamole. The results indicate that the idiopathic recurrent venous thrombosis patient population could be differentiated by the platelet function tests into subgroup I, in which no platelet abnormality could be detected, and subgroup II, where platelet hyperaggregability was present. These results indicate that the role of platelets should be considered in the pathogenesis of recurrent venous thrombosis and therapy with agents which inhibit platelet aggregation may be beneficial in the patients with platelet hyperaggregability.

Vitamin E. An inhibitor of the platelet release reaction

Formation of lipid peroxides rises sharply when platelets undergo the release reaction. In this study the in vitro effect of vitamin E on platelet aggregation was investigated. alpha-Tocopherol, an anitoxidant of known inhibitory action on lipid peroxidation, was added to platelet suspensions in concentrations up to 1.5 mM. A dose-dependent reduction in platelet aggregation was observed, with complete inhibition of the secondary wave of aggregation at greater than or equal to 0.9 mM alpha-tocopherol. The inhibitory effect of alpha-tocopherol on the platelet release reaction was further documented by the decrease in aggregation-induced release of [14C]5-hydroxytryptamine from prelabeled platelets and by the reduction of N-acetylglucosaminidase activity released into the medium. The sharp rise in lipid peroxides normally associated with platelet aggregation was markedly reduced by alpha-tocopherol and also by acetylsalicylic acid, a known inhibitor of the platelet release reaction. In vivo studies examined the effect of oral vitamin E administration (1,200-2,400 IU daily) on plasma and platelet levels of alpha-tocopherol. Up to 1,800 IU daily, increasing dosages of vitamin E resulted in increasing concentrations of alpha-tocopherol in plasma and platelets, but intake of vitamin E in excess of this dosage failed to show any further increase in plasma or platelet levels.

Inhibition of platelet release reaction by acetylsalicylic acid

The inhibitory potency and duration of action of single doses of aspirin B.P., claradin (a low sodium effervescent preparation of acetylsalicylic acid) and aloxiprin (an aluminium co-polymer of acetylsalicylic acid) on platelet release reaction induced by adenosine diphosphate (ADP) were studied in seventeen volunteers. Aspirin B.P. and claradin at 300 mg and 150 mg inhibited release reaction in all subjects within 24 hr; 75 mg was effective only in some subjects. Aloxiprin gave less marked response and a dose of 300 mg was required to inhibit the effect in all volunteers. Where occurring, inhibition of release reaction persisted for three days after treatment with all preparations and restoration to normal occurred in most subjects by the sixth day.

A daily dose of 50 mg claradin for 12-15 days in five volunteers produced complete inhibition of release reaction for most of the treatment period. Inhibition of release reaction took up to 3 days to occur. Normal aggregation returned within 3 days of discontinuing treatment in all subjects. A daily dose of 25 mg claradin gave inconsistent results.

It is suggested that if a trial of acetylsalicylic acid be undertaken for the prevention of arterial thrombosis based on its ability to inhibit platelet release reaction then a daily dose of 50 mg would be sufficient.

Salicylates in saliva

The possible excretion of acetylsalicylic acid and salicylic acid into human whole-mouth saliva was studied after the ingestion of 1.0 g of acetylsalicylic acid in gelatine capsules. In addition, the oral clearance of both salicylates was determined after a sham intake of acetylsalicylic acid in solution. No acetylsalicylic acid was excreted in saliva. The maximum concentration of 1.2 mug/ml of the metabolite, salicylic acid, was excreted after 3 hours. Considerable concentrations of both salicylates were retained from 2 to 3 hours in the mouth after the sham intake of the drug in solution. During the retention period, part of the acetylsalicylic acid was hydrolyzed to salicylic acid. In vitro, at low concentration levels about 50% of salicylic acid was bound to salivary proteins. The degree of binding was dependent on the drug concentration. The reason for the absence of excreted acetylsalicylic acid from the saliva was evidently its hydrolysis in the body. Protein binding in the oral cavity may explain the slow clearance of locally applied salicylates. Retention of salicylates in the mouth after the use of drug solutions or effervescent preparations should be considered in, e.g. evaluations of local analgesic effects or bleeding disorders.

Antithrombotic drugs: part II

The defibrinating agent ancrod has had limited clinical trial, but appears to give no advantages over heparin. Intravenous infusion of dextran, a glucose polymer, has been shown to have an antithrombotic effect in many experimental models of thrombosis. However, the evidence that dextran is a clinically valuable antithrombotic drug is conflicting. A number of controlled randomized studies have shown that dextran can prevent postoperative venous thromboembolism when a large volume of dextran 40 or 70 was infused rapidly during and after surgery. However, blood volume expansion during dextran treatment prohibits its use in patients with reduced cardiac reserve, and infrequent though sometimes severe, allergic reactions have been reported. Evidence that dextran is of value for the treatment of venous or arterial thromboembolism comes from uncontrolled studies and is not convincing. Many compounds have been shown to inhibit platelet function in vitro but only five of these drugs have been extensively evaluated as prophylactic or therapeutic antithrombotic agents in man. These are aspirin, sulphinpyrazone, dipyridamole, hydroxychloroquine and clofibrate. They have been evaluated mainly in patients with cerebral vascular disorders, coronary artery disease, peripheral artery ischaemia, venous thromboembolism, prosthetic heart valves, and in patients with arteriovenous shunts. The evaluation of the clinical effect of the platelet function suppressing drugs is in its early stages, but they appear to differ from each other in the spectrum of their clinical effectiveness, and they may be more effective in arterial than in venous thromboembolic disorders. Their role in the management of cerebral vascular disease and coronary artery disease is still uncertain, and should be clarified by the results of a number of multi-centre, prospective, randomized studies which are currently in progress. Three types of thrombolytic drugs have been evaluated clinically; the plasminogen activators streptokinase and urokinase, proteolytic enzymes such as plasmin, and agents which increase the level of endogenous plasminogen activator (e.g. anabolic steroids). Of these, the plasminogen activators now have a definite place in clinical practice. The plasminogen activators accelerate the lysis of recent venous thrombi and pulmonary emboli, and of arterial thrombi or emboli. Thrombolytic therapy with these agents should be considered particularly in patients with recent major pulmonary embolism, as lysis of recent emboli is rapid and substantial. It should also be considered in patients with recent extensive venous thrombosis, because total lysis of venous thrombi has been reported to result in long-term preservation of valve function, and is likely to prevent postphlebitic syndrome, though this has not been proven. However, plasminogen activator therapy carries a higher risk of bleeding than heparin treatment...

Paracetamol/codeine in relieving pain following removal of impacted mandibular third molars

A double-blind clinical study of analgesic drugs was conducted involving 47 healthy adults requiring removal of 90 bony impacted mandibular third molars. The analgesic effect of paracetamol plus codeine (P + C) 350 + 20 mg was compared to that of acetylsalicylic acid (ASA) 500 mg and placebo. A standardized surgical procedure under local anesthesia was used. Insufficient analgesic effect was noted in 16% of the ASA group and in 69% of the placebo group but in none in the P+C group. On the first postoperative day, patients given P+C suffered less pain compared with those given ASA (P less than 0.01). No relationship could be demonstrated between the type of impaction and intensity of pain. Trismus, however, was found to be associated with difficulty of extirpation. Drowsiness and an increased sleeping tendency were the main side effects found in the P+C group. The incidence of secondary hemorrhage was high in the ASA group, compared with the P+C group a significance of 0.01 less than P less than 0.05 was found on various postoperative days. Registration of swelling revealed less postoperative edema in the P+C group than in the ASA group (0.01less thanPless than0.05). The main conclusion from this study is that the analgesic effect of P+C orally administered after a specific oral surgical procedure is superior to ASA and placebo. P+C also appears to have a more marked antiphologistic effect than ASA.

Orthodontics and dentistry for the hemophilic patient

In this presentation we have contrasted the normal blood-clotting mechanism with the failure to form blood clots in hemophiliacs due to the absence of protein factors necessary for conversion of prothrombin to thrombin. The statistics, hereditary basis, and long-term disabling consequences of hemophilia to the severely ffected patient are described. The systemic means of minimizing severe joint disabilities and serious internal bleeding hazards by employing concentrates of antihemophilic factors to reverse the bleeding defects are discussed. Availability and advantages of the types of concentrates are explained. The fatalistic attitude of hemophiliacs toward hepatitis is discussed, along with admonitions to avoid the use of aspirin, alcohol, and buttock injections. Alternative medications for pain are recommended; and injection sites for pediatric patients are suggested. The details of simplified oral surgical management of hemophilic patients without hospitalization are described, including local anesthetic injection technique, method of performing extractions, general anesthesia techniques when indicated, materials for packing of extraction sockets, regimen and precautions in use of Amicar administration for clot maintenance, postoperative diet, and postsurgical activity guidelines. Also noted is the self-administration of intravenous concentrate infusions at home in the event of hemorrhagin, so that bleeding is on the way to bein controlled even before the patient reaches the hospital. We avoided orthodontic treatment of hemophilic patients in the past; however, recently developed bracket-fixation techniques and auxiliary aids; along with an enlightened understanding that gingival bleeding is ot to be feared, have changed our attitude, and we now treat hemophilic patients in much the same manner as otherwise normal orthodontic patients...

Impaired interaction (adhesion-aggregation) of platelets with the subendothelium in storage-pool disease and after aspirin ingestion. A comparison with von Willebrand's disease

Possible defects in the interaction of platelets with the subendothelial surface were evaluated in six patients with storeage-pool disease, nine patients with von Willebrand's disease and seven normal subjects who ingested aspirin. Citrated blood was perfused through a chamber containing everted segments of rabbit aorta previously denuded of endothelium by means of a ballon catheter. With normal blood, 83.3 +/- 1.9 per cent (S.E.M.) of the surface was covered by adherent platelets. Platelet adhesion was normal after aspirin ingestion (89.7 +/- 4.6 per cent) and decreased in some patients with storage-pool disease. The most striking defect in both circumstances was the virtual absence of platelet thrombi. In contrast, decreased adhesion (57.3 +/- 3.4 per cent), but normal thrombus formation, was characteristic of von Willebrand's disease. These types of defects in platelet adhesion and aggregation may account for the hemostatic defects in a variety of bleeding disorders. The findings further suggest the possible usefulness of aspirin as an antithrombotic agent.

[The effect of acetylsalicylic acid, extremely restricted movement and a cholesterol-rich diet on atheromatosis of the rabbit aorta: comparative investigations (author's transl)]

A multifactorial model for demonstrating the pathogenesis of the diet-induced atheromatosis of the rabbit is described. We examined the effect of various diets (atherogenetic, rich in fibre, mixed, normal) and of extreme restriction of movement, with and without doses of acetylsalicylic acid. The aorta showed uniforms morphological findings; 1. Acetylsalicilic acid no influence on the cholesterol-induced atheromatosis of the rabbit; 2. An atherogenic diet and a diet rich in raw fibre caused different degrees of sclerosis of the aorta; this was related to the cholesterol content of the mixed diet, which was 50% less than the cholesterol content of the atherogenic diet; 3. Macro- and microscopic examination showed that extreme restriction of movement alone has no demonstrable effect on the aorta of the rabbit; 4. The cholesterol-induced atheromatosis showed significantly less involvement of the aorta when there was extreme restriction of movement in addition to the diet; 5. In none of the test groups could we demonstrate any effect of PAT I on platelet adhesiveness; 6. The test conditions did not result in an activation of the contact phase of the haemocoagulation system.