Inhibition of platelet aggregation in whole blood by alcohol

The evolving knowledge on primary hemostasis in patients with cirrhosis: A comprehensive review

Patients with cirrhosis develop complex alterations in primary hemostasis that include both hypocoagulable and hypercoagulable features. This includes thrombocytopenia, multiple alterations of platelet function, and increased plasma levels of von Willebrand factor. Contrary to the historical view that platelet dysfunction in cirrhosis might be responsible for an increased bleeding tendency, the current theory posits a rebalanced hemostasis in patients with cirrhosis. Severe thrombocytopenia is not indicative of the bleeding risk in patients undergoing invasive procedures and does not dictate per se the need for pre-procedural prophylaxis. A more comprehensive and individualized risk assessment should combine hemostatic impairment, the severity of decompensation and systemic inflammation, and the presence of additional factors that may impair platelet function, such as acute kidney injury and bacterial infections. Although there are multiple, complex alterations of platelet function in cirrhosis, their net effect is not yet fully understood. More investigations evaluating the association between alterations of platelet function and bleeding/thrombosis may improve risk stratification in patients with decompensated cirrhosis. Besides hemostasis, the assessment of von Willebrand factor Ag and ADP-induced, whole-blood platelet aggregation normalized by platelet count (VITRO score and PLT ratio) are promising biomarkers to predict the risk of hepatic decompensation and survival in both compensated and decompensated patients. Further investigations into the in vivo interplay between platelets, circulating blood elements, and endothelial cells may help advance our understanding of cirrhotic coagulopathy. Here, we review the complex changes in platelets and primary hemostasis in cirrhosis and their potential clinical implications.

Traumatic lingual hematoma after generalized tonic–clonic seizure in a patient with an acquired coagulopathy

Oral lacerations are common complications of seizures and account for 92% of all oral injuries. Seizures are relatively commonly associated with chronic alcohol consumption. It is already known that provoked seizures can occur after a sudden cessation of prolonged alcohol intoxication. Meanwhile, chronic alcohol consumption can disrupt the blood coagulation process on several levels. This report aims to present a case of generalized tonic-clonic seizure in a man with chronic alcoholism and acquired coagulopathy who suffered severe tongue injury during a seizure. A 45-year-old man was brought to the emergency department after a first-in-life generalized tonic-clonic seizure. He gave information that he bit his tongue during the seizure. Shortly afterward, the patient had another generalized seizure during which he stopped breathing and was intubated. On admission, the patient was sedated, intubated, and on mechanical ventilation, with no signs of focal neurological deficit. A detailed physical examination revealed massive tongue swelling, which was significantly moved forward. Laboratory tests revealed coagulopathy (INR 2,10) severe thrombocytopenia with a platelet count of 50x109/L. Electrolyte values were in the reference range. According to the maxillofacial surgeon's recommendation, he was treated conservatively, and after 2 weeks, he was clinically stable with a significant reduction of lingual hematoma and without new epileptic events. In our case, decreased platelet count and probable platelet dysfunction associated with chronic alcohol consumption and tongue bite during generalized tonic-clonic seizure played a significant role in developing lingual hematoma. These fast-developing lingual hematomas can lead to possible airway obstruction; therefore, careful observation and timely intubation are mandatory to prevent possible fatal complications.

Association of the bleeding time test with aspects of traumatic brain injury in patients with alcohol use disorder

BACKGROUND-AIM

Traumatic brain injury (TBI) and alcohol use disorder (AUD) can occur concomitantly and be associated with coagulopathy that influences TBI outcome. The use of bleeding time tests in TBI management is controversial. We hypothesized that in TBI patients with AUD, a prolonged bleeding time is associated with more severe injury and poor outcome.

MATERIAL AND METHODS

Moderate and severe TBI patients with evidence of AUD were examined with bleeding time according to IVY bleeding time on admission during neurointensive care. Baseline clinical and radiological characteristics were recorded. A standardized IVY bleeding time test was determined by staff trained in the procedure. Bleeding time test results were divided into normal (≤ 600 s), prolonged (> 600 s), and markedly prolonged (≥ 900 s). Normal platelet count (PLT) was defined as > 150,000/μL. This cohort was compared with another group of TBI patients without evidence of AUD.

RESULTS

Fifty-two patients with TBI and AUD were identified, and 121 TBI patients without any history of AUD were used as controls. PLT was low in 44.2% and bleeding time was prolonged in 69.2% of patients. Bleeding time values negatively correlated with PLT (p < 0.05). TBI patients with markedly prolonged values (≥ 900 s) had significantly increased hematoma size, and more frequently required intracranial pressure measurement and mechanical ventilation compared with those with bleeding times < 900 s (p < 0.05). Most patients (88%) with low platelet count had prolonged bleeding time. No difference in 6-month outcome between the bleeding time groups was observed (p > 0.05). Subjects with TBI and no evidence for AUD had lower bleeding time values and higher platelet count compared with those with TBI and history of AUD (p < 0.05).

CONCLUSIONS

Although differences in the bleeding time values between TBI cohorts exist and prolonged values may be seen even in patients with normal platelet count, the bleeding test is a marker of primary hemostasis and platelet function with low specificity. However, it may provide an additional assessment in the interpretation of the overall status of TBI patients with AUD. Therefore, the bleeding time test should only be used in combination with the patient's bleeding history and careful assessment of other hematologic parameters.

Blood platelet function abnormalities in cirrhotic patients with esophageal varices in relation to the variceal bleeding history

Objective: The study aimed at assessing the effect of thrombocytopenia and platelet function abnormalities on the occurrence of variceal bleeding in patients with cirrhosis. Methods: The results of impedance aggregometry, von Willebrand factor antigen level and thromboelastometry (TEM) with and without the addition of a platelet inhibitor (FIBTEM^®, EXTEM^® test, respectively) were compared in two patient groups: Group 1 (n = 32) - patients with moderate or large esophageal or gastric varices, who had never had symptoms of acute gastrointestinal bleeding and Group 2 (n = 26) - patients with history of variceal bleeding. Results: Standard clotting test indicated more hypocoagulable profile in Group 2 compared to Group 1. However, no differences in any TEM component were observed between groups in EXTEM^® test. The contribution of platelets to clot strength was significantly higher in Group 2 than in Group 1 [PLT% = 74.2 (67.5-80.4) versus 68.8 (63.7-76.5) %; p = .039]. The aggregation index was also higher in Group 2 compared to Group 1, although not statistically significant [% of healthy = 96.9 (73.2-140.1) versus 67.6 (52.5-118.8) %, p = .195]. No differences in vWF antigen levels were observed between groups. Conclusions: The results of thromboelastometry and aggregometry indicate increased contribution of platelets in clot formation in patients with a history of variceal bleeding compared to cirrhotic patients who never bled. Comparable effectiveness of hemostasis in both groups is most likely associated with the compensatory role of platelets. Increased platelet activity in this group of patients is probably due to a mechanism independent of the von Willebrand factor antigen level.

Exposing the bidirectional effects of alcohol on coagulation in trauma: Impaired clot formation and decreased fibrinolysis in rotational thromboelastometry

BACKGROUND

Alcohol has been associated with altered viscoelastic testing in trauma, indicative of impaired coagulation. Such alterations, however, show no correlation to coagulopathy-related outcomes. Other data suggest that alcohol may inhibit fibrinolysis. We sought to clarify these mechanisms after traumatic injury using thromboelastometry (ROTEM), hypothesizing that alcohol-related clot formation impairment may be counter-balanced by inhibited fibrinolysis.

METHODS

Laboratory, demographic, clinical, and outcome data were prospectively collected from 406 critically injured trauma patients at a Level I trauma center. ROTEM and standard coagulation measures were conducted in parallel. Univariate comparisons were performed by alcohol level (EtOH), with subsequent regression analysis.

RESULTS

Among 274 (58%) patients with detectable EtOH, median EtOH was 229 mg/dL. These patients were primarily bluntly injured and had lower GCS (p < 0.05) than EtOH-negative patients, but had similar admission pH and injury severity (p = NS). EtOH-positive patients had prolonged ROTEM clotting time and rate of clot formation time (CFT/α); they also had decreased fibrinolysis (max lysis %; all p < 0.05). In linear regression, for every 100 mg/dL increase in EtOH, clotting time increased by 13 seconds and fibrinolysis decreased by 1.5% (both p < 0.05). However, EtOH was not an independent predictor of transfusion requirements or mortality. In high-EtOH patients with coagulopathic ROTEM tracings, transfusion rates were significantly lower than expected, relative to EtOH-negative patients with similar ROTEM findings.

CONCLUSION

As assayed by ROTEM, alcohol appears to have a bidirectional effect on coagulation in trauma, both impairing initial clot formation and inhibiting fibrinolysis. This balancing of mechanisms may explain lack of correlation between altered ROTEM and coagulopathy-related outcomes. Viscoelastic testing should be used with caution in intoxicated trauma patients.

LEVEL OF EVIDENCE

Epidemiological study, level III.

New-onset acute thrombocytopenia in hospitalized patients: pathophysiology and diagnostic approach

Thrombocytopenia is a hematological finding commonly encountered in daily clinical practice from asymptomatic clinic patients to critically ill intensive care unit patients. A broad spectrum of etiologies and variation in clinical presentation often present a diagnostic challenge. Furthermore, concomitant presence of thrombosis and thrombocytopenia, as in cases of thrombotic thrombocytopenia, complicates the management. In hospitalized patients, new-onset thrombocytopenia is an important reason for hematology consultation. Therefore, it is of utmost importance that the etiology is diagnosed accurately. In addition, a basic understanding of the pathophysiology and the differential diagnosis avoids delay in the diagnosis and leads to rapid initiation of treatment. This review will address causes of thrombocytopenia that arises in hospitalized patients with an emphasis on the pathophysiological basis of each disorder.

Hemostatic balance in patients with liver cirrhosis: Report of a consensus conference

Patients with cirrhosis present with hemostatic alterations secondary to reduced availability of pro-coagulant and anti-coagulant factors. The net effect of these changes is a rebalanced hemostatic system. The Italian Association of the Study of the Liver (AISF) and the Italian Society of Internal Medicine (SIMI) promoted a consensus conference on the hemostatic balance in patients with cirrhosis. The consensus process started with the review of the literature by a scientific board of experts and ended with a formal consensus meeting in Rome in December 2014. The statements were graded according to quality of evidence and strength of recommendations, and approved by an independent jury. The statements presented here highlight strengths and weaknesses of current laboratory tests to assess bleeding and thrombotic risk in cirrhotic patients, the pathophysiology of hemostatic perturbations in this condition, and outline the optimal management of bleeding and thrombosis in patients with liver cirrhosis.

Ethyl acetate extract from tissue-cultured mountain ginseng adventitious roots inhibits in vitro platelet aggregation in whole human blood and augments peripheral blood flow in mice

We previously reported that in vitro anti-platelet activity of tissue-cultured mountain ginseng (TCMG) ethanol extracts show improved efficacy when compared with commercial ginseng products such as Korean red ginseng and Panax ginseng. However, information on the anti-platelet activity of the ethyl acetate fraction from TCMG adventitious roots is limited. Therefore, in this study, we further investigated the effects of an ethyl acetate extract of TCMG (EA-TCMG) adventitious roots on in vitro antiplatelet activity in whole human blood and its effect on peripheral blood flow in mice. We found that EA-TCMG inhibited platelet aggregation with IC₅₀ values of 271, 180, and 147 μg/mL induced by collagen, adenosine-5΄-diphosphate, and arachidonic acid, respectively. Among the three agonists used, thromboxane A₂ formation induced by arachidonic acid was markedly suppressed. Furthermore, EA-TCMG improved the peripheral circulatory disturbance by improving vascular blood flow. In conclusion, these results suggest that ethyl acetate extracts from TCMG adventitious roots might inhibit vascular platelet aggregation and thrombus formation.

Effects of ethanol on aggregation, serotonin release, and amyloid precursor protein processing in rat and human platelets

It is known that oxidative stress leads to amyloid precursor protein (APP) dysregulation in platelets. Ethanol (EtOH) is a vascular risk factor and induces oxidative stress. The aim of the present study was thus to investigate whether EtOH affects APP processing in rat and human platelets. Platelets were exposed to 50 mM EtOH with and without 2 mM calcium-chloride (CaCl₂) for 20 or 180 minutes at 37°C. Platelet aggregation, serotonin release and APP isoforms 130 and 106/110 kDa were analyzed. As a control, 100 mM H₂O₂ was tested in rat platelets. Our data show that EtOH alone did not affect any of the analyzed parameters, whereas CaCl₂ significantly increased aggregation of rat and human platelets. In addition, CaCl₂ alone enhanced serotonin release in rat platelets. EtOH counteracted CaCl₂-induced aggregation and serotonin release. In the presence of CaCl₂, EtOH reduced the 130 kDa APP isoform in rat and human platelets. In conclusion, this study shows that in the presence of CaCl₂, EtOH affects the platelet function and APP processing in rat and human platelets.

Guidelines for the prevention of stroke in patients with stroke or transient ischemic attack: a guideline for healthcare professionals from the american heart association/american stroke association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of ischemic stroke among survivors of ischemic stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches for atherosclerotic disease, antithrombotic treatments for cardioembolism, and the use of antiplatelet agents for noncardioembolic stroke. Further recommendations are provided for the prevention of recurrent stroke in a variety of other specific circumstances, including arterial dissections; patent foramen ovale; hyperhomocysteinemia; hypercoagulable states; sickle cell disease; cerebral venous sinus thrombosis; stroke among women, particularly with regard to pregnancy and the use of postmenopausal hormones; the use of anticoagulation after cerebral hemorrhage; and special approaches to the implementation of guidelines and their use in high-risk populations.

Alcohol consumption and risk of heart failure: a meta-analysis

BACKGROUND

Heart failure is highly prevalent among older adults and is associated with high treatment costs. Identifying modifiable determinants of heart failure may help in prevention. Alcohol consumption has emerged as a modifiable risk factor for cardiovascular diseases. Although many studies have suggested a positive association between heavy drinking and cardiomyopathy, the association between infrequent or light-to-moderate drinking and heart failure risk has been less conclusive.

PURPOSE

To examine the relation between various levels of alcohol intake and incident heart failure.

METHODS

We conducted a meta-analysis of 6 studies obtained through a PubMed literature search. Alcohol drinkers were classified as never, former, and current drinkers of 0.1 to 0.9, 1 to 7, 8 to 14, and > 14 drinks per week.

RESULTS

Compared with never drinkers, the pooled relative risks were 1.16 (95% confidence interval [CI], 0.90-1.51) for former drinkers, 0.90 (95% CI, 0.83-0.98), 0.80 (95% CI, 0.73-0.88), 0.78 (95% CI, 0.65-0.95), and 0.77 (95% CI, 0.63-0.95) for current drinkers of 0.1 to 0.9, 1 to 7, 8 to 14, and > 14 drinks per week, respectively, in a random effects model.

CONCLUSION

These data suggest that infrequent and light-to-moderate drinking is associated with a lower risk of heart failure.

Hormetic acute response and chronic effect of ethanol on adenine nucleotide hydrolysis in rat platelets

The objective of this study was to verify the acute and chronic effects of ethanol on platelet NTPDase and 5'-nucleotidase activities. These enzymes modulate platelet function by regulating adenine nucleotide bioavailability and adenosine production. In the acute treatment, doses of 0.8, 2.0, 4.0, 6.0 and 8.0 g/kg ethanol were administered via orogastric tube, and induced a biphasic or hormetic effect on ATP, ADP and AMP platelet hydrolysis. Ethanol at a dose of 0.8 and 2.0 g/kg increased NTPDase activity (44 and 35%, P < 0.0001) with ATP as substrate, whereas when ADP was used there was only a tendency for NTPDase activity to increase. ATP and ADP hydrolysis decreased by 31-77% (P < 0.0001) in 4.0, 6.0 and 8.0 g/kg of ethanol compared to the control. AMP hydrolysis showed a tendency to increase at ethanol doses of 0.8 and 2.0 g/kg, but was inhibited by 45-100% (P < 0.0001) at the higher doses. Chronic treatment consisted of the oral administration of 20% ethanol solution during 31 weeks as the only source of liquid and inhibited NTPDase activity (15 and 20%, P < 0.05) with ATP and ADP as substrate, respectively. However, AMP hydrolysis by 5'-nucleotidase increased by 40% (P < 0.05). Thus, we speculate that the effects of ethanol on NTPDase and 5'-nucleotidase activities could be related with the platelets alterations commonly observed in alcohol users.

Review article: blood platelet number and function in chronic liver disease and cirrhosis

BACKGROUND

The liver plays a central role in coagulation and fibrinolysis but is also closely intertwined with the function and number of blood platelets.

AIM

To describe and integrate all literature concerning blood platelets and liver disease by performing a thorough literature research.

METHODS

A thorough literature research on 'blood platelets' and 'liver disease' was performed.

RESULTS

Thrombocytopenia is a marked feature of chronic liver disease and cirrhosis. Traditionally, this thrombocytopenia was attributed to passive platelet sequestration in the spleen. More recent insights suggest an increased platelet breakdown and to a lesser extent decreased platelet production plays a more important role. Besides the reduction in number, other studies suggest functional platelet defects. This platelet dysfunction is probably both intrinsic to the platelets and secondary to soluble plasma factors. It reflects not only a decrease in aggregability, but also an activation of the intrinsic inhibitory pathways. The net effect, finally, is a decreased platelet function in the various types of chronic liver diseases and cirrhosis. Finally, recent data suggest that platelets are not only affected by but can also contribute to the liver disease process, as for instance, in viral hepatitis and cholestatic liver disease.

CONCLUSION

Platelet research in liver disease is a growing area of investigation and could provide new pathophysiological insights.

Alcohol consumption and heart failure: a systematic review

Heart failure (HF) remains a major public health issue. It is estimated that about 500,000 Americans per year are diagnosed with HF. Despite advanced medical and surgical treatments for HF, mortality after the onset of HF is still high, thereby underscoring the importance of primary prevention. Among modifiable lifestyle factors, alcohol consumption appears to play a role in the development of HF. Although excessive drinking has been known to lead to alcoholic cardiomyopathy and light-to-moderate drinking may confer some cardiovascular benefits, recent studies suggest it is not only the quantity, but also drinking patterns and genetic factors, that may influence the relation between alcohol consumption and cardiovascular disease. This article reviews current evidence on the association between alcohol consumption and HF.

The modified Je-Ho-Tang, Korean herbal medicine, inhibits whole-blood aggregation and platelet adhesion to collagen under flow

We investigated the in vitro effect of modified Je-Ho-Tang (MJHT) hot-water extract on platelet aggregation and activation induced by agonists in human whole blood, and on platelet adhesion to a collagen-coated surface under flow shear stress conditions. MJHT extract potently inhibited the collagen-induced platelet aggregation in human whole blood in a dose-dependent manner, with a half-maximal inhibitory dose (IC(50)) value of 526 microg/mL. We accessed several markers of platelet activation using receptor expression on platelet membranes, including GPIIb/IIIa-like expression (PAC-1) and P-selectin (CD62); we monitored the intracellular calcium mobilization response by flow cytometry in healthy subjects. A significant decrease in PAC-1 (P=0.002), CD62 (P=0.002), and intracellular calcium mobilization (P<0.001) were seen in the presence of MJHT extract. In addition, we have used image analysis to study human platelet adhesion to collagen under physiologic flow conditions in a perfusion chamber. MJHT extract markedly decreased platelet adhesion to the collagen-coated surface. These results show that MJHT has potent anti-platelet activity.

Alcohol consumption and risk of heart failure in the Physicians' Health Study I

BACKGROUND

Heart failure (HF) is the leading cause of hospitalization among the elderly, and 1 in 5 adults aged 40 years will develop HF in their lifetime. Data on the effects of moderate alcohol consumption on the risk of HF have been sparse and inconsistent. This study sought to evaluate the association between moderate alcohol consumption and incident HF.

METHODS AND RESULTS

A total of 21,601 participants of the Physicians' Health Study I who were free of HF and provided data on alcohol intake at baseline were prospectively followed up from 1982 to 2005. Incident HF cases were ascertained through annual follow-up questionnaires and validated with the use of Framingham criteria. During an average follow-up of 18.4 years, 904 incident cases of HF occurred. The crude incidence rates of HF were 25.0, 20.0, 24.3, and 20.6 cases per 10,000 person-years for alcohol categories of <1, 1 to 4, 5 to 7, and >7 drinks per week, respectively. Corresponding hazard ratios (95% CI) were 1.0 (reference), 0.90 (0.76 to 1.07), 0.84 (0.71 to 0.99), and 0.62 (0.41 to 0.96), respectively, with P for trend=0.012 adjusted for age, body mass index, smoking, and history of valvular heart disease. There was no evidence for a strong association between moderate alcohol consumption and HF without antecedent coronary artery disease.

CONCLUSIONS

Although heavy drinking should be discouraged, our data indicate that moderate drinking may lower the risk of HF. The lack of an association between moderate alcohol intake and HF without antecedent coronary artery disease suggests that possible benefits of moderate drinking on HF may be mediated through beneficial effects of alcohol on coronary artery disease.

Inhibition of PAR4 Signaling Mediates Ethanol-Induced Attenuation of Platelet Function In Vitro

BACKGROUND

Reduction in coronary heart disease morbidity in response to moderate consumption of alcoholic beverages may be partly mediated by ethanol-induced inhibition of platelet function. However, the precise mechanisms by which ethanol modulates platelet activation induced by thrombin, which plays a central role in hemostasis, remain unclear. The goal of this study was to investigate ethanol-induced changes in platelet function and clarify the underlying mechanisms including PAR1 and PAR4 activity and [Ca2+]i dynamics in vitro.

METHODS

Platelet aggregation, increase in intracellular calcium ([Ca2+]i), and release of platelet factor 4 and beta-thromboglobulin induced by alpha-thrombin, PAR1-agonist peptide (AP), or PAR4-AP were assessed in the presence or absence of ethanol.

RESULTS

Ethanol exposure inhibited low-dose thrombin (0.5 nM)-induced aggregation but not an increase in [Ca2+]i. In contrast, ethanol had no effect on high-dose thrombin (10 nM)-induced aggregation or the [Ca2+]i increase. Ethanol did not significantly inhibit thrombin-induced release of platelet factor 4 and beta-thromboglobulin. Ethanol reduced PAR1-AP-induced aggregation, but did not affect the spike form of [Ca2+]i increase. In contrast, ethanol inhibited the increase in [Ca2+]i as well as the aggregation in response to PAR4-AP and resulted in delayed [Ca2+]i peak time. Furthermore, ethanol inhibited both PAR1-AP- and PAR4-AP-induced platelet factor 4 and beta-thromboglobulin release.

CONCLUSIONS

These data suggest that ethanol inhibits platelet aggregation via inhibition of PAR4 signaling and subsequent inhibition of Ca2+ influx and granule release. This phenomenon may contribute to the reduction in coronary heart disease morbidity in response to consumption of alcoholic beverages.

Anti-platelet effects of bioactive compounds isolated from the bark of Rhus verniciflua Stokes

It has previously been shown that EtOAc extracts of Rhus verniciflua Stokes (RVS) inhibit the platelet aggregation response. In this report, bioassay-guided fractionation using ADP-, arachidonic acid-, and collagen-induced human platelet aggregation by a whole blood aggregometer yielded the bioactive compounds isomaltol and pentagalloyl glucose from different highly effective fractions. In addition, column chromatography of fractions from RVS yielded another five compounds: butin, fisetin, sulfuretin, butein and 3,4',7,8-tetrahydroxyflavone. We investigated the effects of bioactive compounds from RVS fractions on several markers of platelet activation using receptor expression on platelet membranes, including glycoprotein IIb/IIIa (CD41), GPIIb/IIIa-like expression (PAC-1) and P-selectin (CD62), and intracelluar calcium mobilization responses by flow cytometry in healthy subjects. Dose-dependent inhibition of platelet aggregation and significantly decreased platelet activation were observed for the isomaltol- and pentagalloyl glucose-treated platelets, respectively. These results show that isomaltol and pentagalloyl glucose from the bark of Rhus verniciflua Stokes have potent anti-platelet activity and emphasize the need to further examine the mechanism of these active compounds for platelet modulation.

Primary Prevention of Ischemic Stroke

Background and Purpose— This guideline provides an overview of the evidence on various established and potential stroke risk factors and provides recommendations for the reduction of stroke risk.

Methods— Writing group members were nominated by the committee chair on the basis of each writer’s previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee. The writers used systematic literature reviews (covering the time period since the last review published in 2001 up to January 2005), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations based on standard American Heart Association criteria. All members of the writing group had numerous opportunities to comment in writing on the recommendations and approved the final version of this document. The guideline underwent extensive peer review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

Results— Schemes for assessing a person’s risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to their potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic factors. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, alcohol abuse, drug abuse, oral contraceptive use, sleep-disordered breathing, migraine headache, hyperhomocysteinemia, elevated lipoprotein(a), elevated lipoprotein-associated phospholipase, hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

Conclusion— Extensive evidence is available identifying a variety of specific factors that increase the risk of a first stroke and providing strategies for reducing that risk.

Guidelines for Prevention of Stroke in Patients With Ischemic Stroke or Transient Ischemic Attack

The aim of this new statement is to provide comprehensive and timely evidence-based recommendations on the prevention of ischemic stroke among survivors of ischemic stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches for atherosclerotic disease, antithrombotic treatments for cardioembolism, and the use of antiplatelet agents for noncardioembolic stroke. Further recommendations are provided for the prevention of recurrent stroke in a variety of other specific circumstances, including arterial dissections; patent foramen ovale; hyperhomocysteinemia; hypercoagulable states; sickle cell disease; cerebral venous sinus thrombosis; stroke among women, particularly with regard to pregnancy and the use of postmenopausal hormones; the use of anticoagulation after cerebral hemorrhage; and special approaches for the implementation of guidelines and their use in high-risk populations.

Rapid intake of alcohol (binge drinking) inhibits platelet adhesion to fibrinogen under flow

BACKGROUND

Moderate alcohol consumption is associated with decreased mortality from cardiovascular disease. Drinking large amounts in a short period (binge drinking) is associated with increased cardiovascular morbidity. We tested whether rapid consumption of a large dose of alcohol affects platelet aggregation and adhesion.

METHODS

Healthy volunteers (n = 20) were asked to drink three glasses of alcohol or red wine in a 45-min period. Thereafter, another 45 min was allowed for absorption of alcohol. Ninety minutes after the start of the experiment, blood was collected. This entire cycle was repeated once, resulting in consumption of six alcohol-containing drinks in 3 hr. Adenosine-diphosphate (ADP)-induced aggregation was measured and platelet adhesion to fibrinogen and collagen was measured in a perfusion chamber at shear rates of 300/sec and 1600/sec. Platelet coverage and aggregate size were measured.

RESULTS

Acute alcohol intake significantly increased platelet aggregation in suspension when stimulated with low concentrations of ADP (0.1 and 0.5 microg/ml). This effect was not observed when consuming red wine. In contrast, adhesion to fibrinogen was significantly inhibited by alcohol but not red wine at high shear rate after six drinks (p = 0.025). The inhibition was accompanied by a reduction in aggregate size at 90 and 180 min after the start of the experiment. Adhesion to collagen was not altered by either alcohol or red wine.

CONCLUSIONS

Rapid intake of alcohol increases platelet aggregation, which might contribute to the increased mortality associated with binge drinking. Red wine does not show increased platelet aggregation, which might support the reduction of cardiovascular disease in red wine consumers. However, alcohol inhibits platelet adhesion to fibrinogen-coated surface under flow. The diminished adhesion might contribute to the cardioprotective effects of alcohol.

BLOOD COAGULATION TESTS IN TOXICOLOGICAL STUDIES-REVIEW OF METHODS AND THEIR SIGNIFICANCE FOR DRUG SAFETY ASSESSMENT-

In general toxicological studies, prothrombin time and activated partial thromboplastin time are routinely measured to assess blood coagulation. Special (problem-driven) tests for blood coagulation are of significance to detect abnormalities and investigate the mechanism of toxicity in detail. In this review, we compiled widely scattered information on blood coagulation testing from different fields in the biological area, and reviewed the methods available and their significance in toxicological studies. The relevant literature cited here reports large species differences in platelet aggregation, coagulation factors or fibrinolysis, and technical limitations. However, the following tests are basically applicable to laboratory animals; (1) assays for individual coagulation factors and protein induced by vitamin K absence or antagonists (PIVKA) to investigate coagulation factor abnormalities; (2) platelet aggregation-, platelet adhesion-, platelet release-tests and von Willebrand factor assay to screen and/or investigate platelet dysfunction; (3) fibrin/fibrinogen degradation products (FDP), D-dimer and thromboelastogram to detect fibrinolitic abnormalities, and assays for plasminogen, plasmin and their activator/inhibitor to investigate fibrinolysis in detail; and (4) bleeding-time to grossly evaluate blood coagulation capability in vivo. An appropriate battery of these tests provides significant information for risk assessment of drugs.

Alcohol consumption and risk of ischemic stroke: The Framingham Study

BACKGROUND AND PURPOSE

Stroke is a major cause of death in the United States. The association between alcohol consumption and ischemic stroke (IS) remains controversial.

METHODS

We used data collected on participants in the Framingham Study to assess the association between total alcohol intake and type of alcoholic beverage and development of IS, overall and according to age.

RESULTS

A total of 196 men and 245 women developed IS during three 10-year follow-up periods. In the categories of never drinkers, drinkers of 0.1 to 11, 12 to 23, and > or =24 g/d of ethanol (a "typical drink" is approximately 12 g of ethanol), and former drinkers of 0.1 to 11 and > or =12 g/d, crude incidence rates of IS were 6.5, 5.9, 4.9, 5.0, 6.7, and 17.8 cases per 1000 person-years, respectively, for men and 5.9, 4.1, 4.1, 4.3, 8.3, and 7.1, respectively, for women. Overall, compared with never drinkers in a multivariate Cox regression, current alcohol consumption was not related significantly to IS in either sex. Former drinking of > or =12 g/d of alcohol was associated with a 2.4 times higher risk of IS among men but not among women. When stratified by age, alcohol intake was associated with lower risk of IS among subjects aged 60 to 69 years. In beverage-specific analysis, only wine consumption was related to a decreased risk of IS.

CONCLUSIONS

Our data showed no significant association between total alcohol and IS overall but showed a protective effect of alcohol among subjects aged 60 to 69 years.

Beneficial effect of moderate alcohol consumption on vascular disease: myth or reality?

Moderate ethanol consumption (1-3 drinks/day on 5-6 days/week) has a favourable effect on vascular disease-related mortality and morbidity [especially ischaemic heart disease (IHD)]. This cardioprotective effect may be due to significant effects on cardiovascular risk factors such as high density cholesterol (HDL) concentration (HDL protects from IHD) and an inhibition of platelet aggregation (increased platelet aggregability predicts coronary events). In contrast, alcoholics and problem drinkers have an excess of IHD-related, and possibly stroke-related, mortality. Excessive alcohol intake may raise the blood pressure. Prolonged alcohol abuse can also result in alcoholic heart muscle disease. Alcohol is the major cause of non-ischaemic cardiomyopathy in Western society. Although there is a widespread belief that red wine protects more than other alcoholic beverages, several studies do not support this interpretation.

Light-to-moderate alcohol consumption and the risk of stroke among U.S. male physicians

BACKGROUND

Several studies have shown U- or J-shaped relations between alcohol consumption and the risk of stroke. We evaluated the effect of light-to-moderate alcohol intake on the risk of stroke, with separate analyses of ischemic stroke and hemorrhagic stroke.

METHODS

Our analyses were based on a prospective cohort study of 22,071 male physicians, 40 to 84 years old, who were participating in the Physicians' Health Study. At base line, the participants reported that they had no history of stroke, transient ischemic attack, or myocardial infarction and were free of cancer. Alcohol intake, reported by 21,870 participants at base line, ranged from none or almost none to two or more drinks per day.

RESULTS

During an average of 12.2 years of follow-up, 679 strokes were reported. As compared with participants who had less than one drink per week, those who drank more had a reduced overall risk of stroke (relative risk, 0.79; 95 percent confidence interval, 0.66 to 0.94) and a reduced risk of ischemic stroke (relative risk, 0.77; 95 percent confidence interval, 0.63 to 0.94). There was no statistically significant association between alcohol consumption and hemorrhagic stroke. The overall relative risks of stroke for the men who had one drink per week, two to four drinks per week, five or six drinks per week, or one or more drinks per day were 0.78 (95 percent confidence interval, 0.59 to 1.04), 0.75 (95 percent confidence interval, 0.58 to 0.96), 0.83 (95 percent confidence interval, 0.62 to 1.11), and 0.80 (95 percent confidence interval, 0.64 to 0.99), respectively, in an analysis in which we controlled for major risk factors for stroke.

CONCLUSIONS

Light-to-moderate alcohol consumption reduced the overall risk of stroke and the risk of ischemic stroke in men. The benefit is apparent with as little as one drink per week. Greater consumption, up to one drink per day, does not increase the observed benefit.

Moderate drinking and cardiovascular health

Moderate alcohol consumption (1-2 drinks a day) can be beneficial in reducing the risk of coronary artery disease. This article focuses on cellular and molecular mechanisms underlying the beneficial effect of moderate drinking, including increased plasma high-density lipoprotein levels, changes in cellular signaling, reduction in platelet function, stimulation of fibrinolysis, and reduction in ischemia-reperfusion injury. While moderate drinking may be protective against coronary artery disease for some individuals, populations such as pregnant women and individuals who are about to operate motor vehicles or heavy machinery should not drink alcoholic beverages. People with family histories of alcoholism should exercise extreme caution in their decision to drink.

Inhibition of platelet aggregation in whole blood after exposure of rats to alcohol by inhalation

The dose-effect relationship between blood alcohol concentration (BAC) and altered platelet function was examined in whole blood in a rat model of alcohol exposure by inhalation, using the impedance method of ex vivo whole blood platelet aggregation. With rates of alcohol addition to the chamber air inflow from 29 to 56 mg ethanol/l air/min, BAC was dependent on duration of exposure and concentration of alcohol in the air. Next, 3, 6, and 9 h exposures to the highest delivery rate were used, and platelet aggregability was tested. After 9 h, BAC reached 453 +/- 16 mg% and aggregation responses to three doses of collagen were significantly lower than in control blood (p < 0.01). Less consistent inhibition was observed with arachidonic acid and ADP, and also when exposure duration was reduced. However, some significant inhibition of collagen-induced aggregation (p < 0.05) was observed with BAC as low as 127 +/- 15 mg%. These experiments demonstrate that in vivo alcohol exposure inhibits, in a concentration-dependent manner, ex vivo rat whole blood platelet aggregation, at BACs readily attained in humans by ingestion.

Inhibitory effect of alcohol on cyclic GMP accumulation in human platelets

The effects of ethanol on cyclic GMP (cGMP) in washed human platelets were studied in the presence and absence of sodium nitroprusside (SNP), nitric oxide donor which stimulates guanylate cyclase. SNP stimulated cGMP accumulation in a dose-dependent fashion. After 1 min exposure to 100 microM SNP, the level of cGMP was approximately four-fold that in vehicle-treated platelets. Alcohol had no effect on basal cGMP, but inhibited SNP-induced cGMP accumulation at 17, 85 and 170 mM. In further experiments, platelets were incubated for 0, 0.5, 1 2 or 5 min with 10 microM SNP, with or without 100 microM zaprinast, a selective cGMP-phosphodiesterase (PDE) inhibitor and 85 mM ethanol. In the presence of zaprinast but not alcohol, cGMP levels rose continuously, to 10-fold the basal level at 5 min. Without zaprinast, cGMP levels were lower and reached a plateau by 2 min. Accumulation of cGMP was attenuated by alcohol 2 and 5 min after SNP addition, both in zaprinast-treated platelets and those without zaprinast. Thus, alcohol inhibits platelet cGMP accumulation stimulated by nitric oxide donor. Its mechanism probably does not involve a major effect on PDE, because the inhibition was observed in the presence or absence of zaprinast. We hypothesize that alcohol inhibits guanylate cyclase, contributing to its complex functional effects in platelets.