Role of elevated alpha2-macroglobulin revisited: results of a case-control study in children with symptomatic thromboembolism.

OBJECTIVE: alpha(2)-Macroglobulin (alpha2MG) is a broad-spectrum protease inhibitor that is known to neutralize alpha-thrombin, plasmin, and activated protein C, which suggests that it has anticoagulant as well as procoagulant properties. The present study was conducted to evaluate the role of alpha2MG in children with venous thromboembolism [VTE: paradoxical embolism causing ischemic stroke (IS) or deep-vein thrombosis (DVT)]. METHODS: alpha2MG levels measured after acute VTE onset in white patients were compared with data obtained from age- and gender-matched healthy controls. In addition, to compare the rate of elevated alpha2MG and prothrombotic risk factors [factor V G1691A, prothrombin G20210A, raised lipoprotein (a)] between patients and controls and to evaluate the interaction between elevated alpha2MG levels and other thrombophilias, odds ratios (ORs) together with 95% confidence intervals (CIs) were estimated using a logistic regression model. The model was adjusted for age and fibrinogen. RESULTS: alpha2MG levels were significantly higher in patients than in controls (320/139-524 vs. 302/109-406; P = 0.005). In the group of patients (IS n = 103; DVT n = 92), the risk of symptomatic thromboembolism was significantly increased with elevated alpha2MG levels, with a gradual increase per mg dL(-1). In addition, when elevated alpha2MG levels > 90th percentile were compared with values below the cut-off, including established prothrombotic risk factors in the multivariate analysis, patients had a significantly increased OR/95% CI for fibrinogen-adjusted alpha2MG levels (IS, 5.9/1.9-18.3; DVT, 7.2/2.1-24.4). CONCLUSIONS: The procoagulant properties of elevated alpha2MG levels independently increase the odds of stroke and DVT in white children.

Ischemic stroke in young HIV-positive patients in Kwazulu-Natal, South Africa.

Cerebrovascular disease occurs in HIV-positive individuals, but no relationship between the two has been established. The authors reviewed a cohort of patients aged 15 to 44 years to evaluate stroke in HIV-positive and negative subjects. Patients who were HIV-positive with no other identifiable etiology were compared to age- and race-matched HIV-negative patients. HIV-positive and HIV-negative groups did not differ in angiographic, cardiac, or serologic tests. A positive HIV test does not provide causal information or diagnosis.

Plasma endothelin-1 levels in patients with rheumatic mitral stenosis and a history of cerebral thromboembolism.

BACKGROUND: Increased plasma endothelin-1 concentrations have been observed in patients with rheumatic mitral stenosis. Endothelin-1 levels have never been investigated in patients with mitral stenosis and history of cerebral thromboembolism. METHODS: We measured plasma concentrations of endothelin-1 in the peripheral venous blood samples obtained from 20 patients with moderate to severe rheumatic mitral stenosis (16 with permanent atrial fibrillation and 4 with sinus rhythm). Six patients had history of thromboembolism. The remaining 14 patients did not have history of thromboembolism. Plasma endothelin-1 concentrations were measured using solid phase sandwich enzyme linked-immuno-sorbent assay. RESULTS: The peripheral venous concentrations of endothelin-1 of the six patients with history of thromboembolism did not differ from the concentrations of the 14 patients without history of thromboembolism (2.40 +/- 1.39 pg/ml vs. 2.49 +/- 0.66 pg/ml, p = 0.9). CONCLUSIONS: Although plasma endothelin-1 concentrations were increased in patients with mitral stenosis, plasma endothelin-1 concentrations were not further elevated in patients with mitral stenosis and history of thromboembolism.

Plasma homocyst(e)ine concentrations and the risk of subtypes of cerebral infarction. The Hisayama study.

Moderately elevated plasma total homocyst(e)ine (tHcy) levels have been linked with cardiovascular disease. However, the findings of previous studies regarding the relationship between tHcy levels and subtypes of cerebral infarction (CI) have been conflicting. The aim of the present study was to examine this issue in a community-based case-control study performed in Hisayama Town in Japan. Fasting tHcy levels were compared among 75 CI cases, of which 43 were lacunar (LI), 24 atherothrombotic (ATI) and 8 cardioembolic infarctions (CEI), and 248 age- and sex-matched healthy controls. The mean tHcy concentrations were higher in CI than in controls (13.0 vs. 11.8 micromol/l; p = 0.018). LI and CEI also had significantly higher tHcy levels than did the corresponding controls (12.3 vs. 11.3 micromol/l for LI; p = 0.037 and 16.3 vs. 12.7 micromol/l for CEI; p = 0.036). The same tendency was also observed for ATI, but the difference was only marginally significant probably due to the small number of the cases (13.4 vs. 11.9 micromol/l; p = 0.087). After adjustment for age, sex, hypertension, serum creatinine, total protein, folate and vitamin B(12) levels, the risk of LI was not significant in the second tertile of the tHcy distribution, but significantly increased in the third compared with the first tertile (adjusted odds ratio, AOR, 3.4; 95% confidence limits, CL, 1.3-8.9; p = 0.015), while the risk of ATI was significant even in the second tertile (AOR, 5.0; 95% CL, 1.0-23.7; p = 0.042) and higher in the third tertile (AOR, 7.5; 95% CL, 1.5-38.3; p = 0.015). However, the odds ratios for CEI could not be estimated, as there was no case of CEI in the first tertile. These findings suggest that elevated tHcy is an independent risk factor for all subtypes of CI, but that its impact is higher in ATI and probably in CEI than in LI.

Alterations to haemostasis following cardiopulmonary bypass and the relationship of these changes to neurocognitive morbidity.

Cardiopulmonary bypass (CPB) is routinely utilized to provide circulatory support during cardiac surgical procedures. The morbidity of CPB has been significantly reduced since its introduction 50 years ago; however, cerebral injury remains a potentially serious consequence of otherwise successful surgery. The risk of stroke postoperatively is approximately 1-5%. Incidence rates for neurocognitive deficit, however, vary markedly depending on the detection method, although typically it is reported in at least 50% of patients. The aetiology of this cerebral injury remains open to debate, although evidence shows that ischaemia secondary to microembolism may be the principal factor. Emboli originate from bubbles of air, atheroemboli released on aortic manipulation and thromboemboli generated as a result of haemostatic activation. Significant generation of thrombin occurs during CPB resulting in fibrin formation, although the trigger of this activation is not fully understood. Rather than originating from contact activation as previously thought, the primary trigger may be via the activated factor VII/tissue factor pathway of coagulation, with an additional role of contact activation in amplification of coagulation as well as the fibrinolytic response to CPB. Haemostatic activation is inhibited with systemic heparin therapy. The relationship between haemostatic activation and emboli formation during CPB is not known. Interventions to reduce cerebral injury in the context of cardiac surgery depend, in large part, on the minimization of emboli. This review investigates cerebral injury after cardiac surgery and evidence showing that microembolism is the principal causative agent. Fibrin emboli are postulated to be an important source of cerebral embolism. The mechanism of haemostatic activation during CPB is therefore also discussed.

Polymorphism of the lipoprotein lipase gene and risk of atherothrombotic cerebral infarction in the Japanese.

BACKGROUND AND PURPOSE: Lipid and lipoprotein abnormalities have been implicated in the pathogenesis of ischemic cerebrovascular disease and atherosclerosis. Lipoprotein lipase (LPL) plays an important role in plasma lipoprotein metabolism. Several studies have recently reported the presence of a relationship between Ser447Stop mutation of LPL and coronary artery disease. Other polymorphisms (HindIII and PvuII) of the LPL gene have already been shown to correlate significantly with dyslipidemia. We investigated whether these polymorphisms are associated with increased risk of ischemic cerebrovascular disease (CVD). METHODS: We recruited 177 CVD patients (atherothrombotic infarction, n=71; cardioembolic infarction, n=30; lacunar infarction, n=76) and 177 healthy control subjects. Subjects were genotyped for the Ser447Stop mutation and for HindIII/PvuII restriction fragment length polymorphisms of the LPL gene, and the findings were investigated for associations with the clinical subtypes of CVD and with lipid levels. RESULTS: The Ser447Stop mutation correlated significantly with CVD (0.107 versus 0.158; P=0.035). For the CG+GG versus CC genotype, the odds ratio between control subjects and CVD patients with atherothrombotic infarction was 0.42 (95% CI, 0.18 to 0.99) (P=0.046). Serum HDL cholesterol and triglyceride levels did not correlate significantly with the Ser447Stop genotype. HindIII polymorphism correlated significantly with CVD (0.234 versus 0.169; P=0.031), but the frequency of PvuII polymorphism was not significantly different between groups. CONCLUSIONS: Our results suggest that the Ser447Stop mutation of the LPL gene is a novel genetic marker for low risk of atherothrombotic cerebral infarction.

Intraoperative embolus formation during cardiopulmonary bypass affects the release of S100B.

BACKGROUND: Intraoperative thromboembolism and the systemic inflammatory reaction are thought to play a role in causing cerebral dysfunction following cardiopulmonary bypass (CPB). Increased levels of S100B, an astroglial protein, have been linked to neuropsychological deficits after CPB. The present study investigated whether S100B release correlates with intraoperative embolus formation, thrombin formation, or the release of inflammatory parameters. METHODS: 40 patients undergoing coronary artery bypass grafting were included. Blood samples were taken before, during, and after CPB, and levels of S100B, thrombin-antithrombin complex (TAT), complement C5a, and interleukin 8 were analysed. Embolus formation was assessed by Doppler ultrasound at the arterial line of CPB. RESULTS: The release of S100B correlated with embolus count (r = 0.42; p = 0.009) and TAT formation (r = 0.71; p = 0.0001). The correlation of S100B with interleukin 8 (r = 0.58; p = 0.0001) was due to the dependence of both parameters on bypass time (r = 0.29; p = 0.075, partial correlation). A correlation of S100B with C5a formation could not be observed. CONCLUSIONS: S100B release is related to embolus and thrombin formation during CPB, indicating that thrombofibrinous embolism is involved in perioperative brain damage. Inflammatory parameters (i.e. interleukin 8 and C5a) seem to have no influence on S100B release.

Low levels of heparin-releasable tissue factor pathway inhibitor in young patients with thrombosis.

An association between deficiency of tissue factor pathway inhibitor (TFPI) and thrombosis has not been clearly demonstrated in humans, but previous studies have focused on the measurement of plasma TFPI, which is only a small part of the total body TFPI. The major fraction of this natural anticoagulant can be measured in plasma after release by heparin injection. To investigate if deficiency of heparin-releasable TFPI is associated with thrombosis. we measured TFPI activity in plasma before and 10 min after intravenous injection of 7500 IU unfractionated heparin in 64 young patients with venous thrombosis, 49 young patients with arterial thrombosis and 38 healthy individuals. Post-heparin TFPI activity levels were significantly lower in the group of patients with venous thrombosis than in controls (mean+/-SD: 230%+/-39 vs 260%+/-34, p = 0.0002), whereas there was no difference for patients with arterial thrombosis. Defining the normal range as the mean+/-2 SD of TFPI activity in controls, twelve patients had low post-heparin TFPI activity levels, seven with venous and five with arterial thrombosis. Low levels of TFPI activity were confirmed by immunoassay in six of the seven patients with venous thrombosis and two of the five patients with arterial thrombosis, and were present also in at least one first degree relative of six patients, suggesting that the defect might be inheritable. However, the causative role of low heparin-releasable TFPI remains uncertain, because co-segregation of the defect with thrombotic symptoms could not be demonstrated in the small number of families studied.

A novel free radical scavenger, nicaraven, inhibits human platelet aggregation in vitro.

The present study was undertaken to investigate whether or not radical scavengers can inhibit platelet aggregation in humans. Toward this end, nicaraven was selected for this study because it has been shown to specifically scavenge hydroxyl radicals that are implicated in platelet aggregation. Ten healthy volunteers and 10 patients with cerebral thrombosis were enrolled in this study. The antiplatelet activities in vitro of nicaraven were examined. The concentrations of nicaraven tested were 3.50 x 10(-5) mol/L, 1.75 x 10(-4) mol/L, 3.50 x 10(-4) mol/L, and 1.75 x 10(-3) mol/L, respectively. The maximum aggregation rate induced by adenosine diphosphate (ADP) was significantly inhibited by nicaraven at concentration ranges of 3.50 x 10(-4) mol/L or higher in the healthy volunteer platelets. The maximum aggregation rate induced by collagen was significantly inhibited by 1.75 x 10(-3) mol/L of nicaraven. Using platelets from patients with cerebral thrombosis, the maximum aggregation rate induced by ADP was significantly inhibited by 1.75 x 10(-3) mol/L of nicaraven. Furthermore, the maximum aggregation rate induced by collagen were significantly reduced by 1.75 x 10(-3) mol/L of nicaraven. Nicaraven induces dose-dependent inhibition of platelet aggregation in both healthy volunteers and patients with cerebral thrombosis.

The white blood cell and plasma fibrinogen in thrombotic stroke. A significant correlation.

OBJECTIVES: Thrombotic stroke is a common disorder with considerable mortality and morbidity. Risk factors for stroke include cigarette smoking, hypertension and hyperlipidaemia and these have been linked to abnormalities of haemorrheology and coagulation such as increased fibrinogen. Other haemorrheological abnormalities have also been documented. These include an elevation in the white blood cell (WBC) count. The aim of our study was to evaluate plasma fibrinogen, WBC aggregation and the release of free radicals in thrombotic stroke. EXPERIMENTAL DESIGN: Thirty-four patients with thrombotic stroke were enrolled in the study. The data were compared to 58 matched controls. SETTING: This study was carried out in Ninewells Hospital, Dundee on patients previously admitted to the medical wards with acute stroke. MEASURES: Plasma fibrinogen, WBC aggregation and plasma malondialdehyde (MDA) were measured in this study. RESULTS: As expected, the stroke patients have a significantly higher fibrinogen level (4.3+/-1.2 g/dl versus 3.1+/-0.6, p<0.001). WBC aggregation is also increased in the patient group (47.5+/-10.4% versus 42.7+/-10.6, p=0.036), as is plasma MDA (8.6+/-2.0 micromol/l versus 7.1+/-1.07, p<0.001). The factor VIII von Willebrand factor antigen measured as a marker as vascular damage was also significantly higher in the patient group (251+/-87% versus 182+/-64, p<0.001). There was also a statistically significant correlation between fibrinogen level and WBC aggregation, and fibrinogen and MDA. These are both statistically significant p=0.012 and p<0.001 respectively. CONCLUSIONS: We believe our study suggests that enhanced WBC aggregation/adhesion with release of free radicals may be another mechanism whereby fibrinogen exerts its known detrimental effect in stroke development. This may allow planning of therapeutic strategies as yet undeveloped.

Moderate ovarian hyperstimulation syndrome complicated by deep cerebrovascular thrombosis.

This report describes two cases that developed moderate ovarian hyperstimulation syndrome (OHSS) without evidence of haemoconcentration. Both patients developed serious cerebrovascular thrombosis resulting in hemiparesis, and recovered after treatment with anticoagulants. This report emphasizes that other factors may contribute to vascular thrombosis, and illustrates that cerebrovascular accidents may complicate even moderate OHSS.

Cerebral emboli and serum S100beta during cardiac operations.

BACKGROUND: The glial protein S100beta has been used to estimate cerebral damage in a number of clinical settings. The purpose of this investigation was to determine the correlation between cerebral microemboli and S100beta levels during cardiac operations. METHODS: Transcranial Doppler ultrasonography was used to measure emboli in the right middle cerebral artery. Emboli counts (n = 111) were divided into five time periods: (1) incision to aortic cannulation; (2) aortic cannulation to cross-clamp onset; (3) cross-clamp onset to cross-clamp release; (4) cross-clamp release to decannulation; and (5) decannulation to chest closure. The level of S100beta (n = 156) was measured at baseline, at the end of cardiopulmonary bypass, then 150 and 270 minutes after cross-clamp release. RESULTS: The level of S100beta correlated with age, cardiopulmonary bypass time, cross-clamp time, and number of emboli at time period 2. Although cardiopulmonary bypass time was univariately associated with S100beta level, it became nonsignificant in a multivariable model that included age and cross-clamp time. CONCLUSIONS: The correlation of S100beta level with emboli measured during cannulation (time period 2) supports the hypothesis that cannulation is a high-risk time period for cerebral injury.

Cerebrovascular disease risk factors: neuroradiologic findings in patients with activated protein C resistance.

PURPOSE: To assess the patterns of abnormal neuroradiologic findings in patients with a hypercoagulable state related to activated protein C (APC) resistance. MATERIALS AND METHODS: Records in 23 patients with a hypercoagulable state related to APC resistance (18 women, five men; average age, 44.5 years) were reviewed for cerebrovascular disease risk factors and other causes of a hypercoagulable state. Computed tomographic scans, magnetic resonance (MR) images, angiograms, and transesophageal echocardiograms were also reviewed. RESULTS: Stroke risk factors or other causes of a hypercoagulable state were found in 12 patients. Arterial infarcts were seen in 18 patients. Hyperintense white matter foci were seen on MR images in six patients. Dural sinus thrombosis was found in four patients. Angiograms of intracranial circulation in six patients showed major artery occlusions in four. MR angiograms in four patients showed internal carotid artery occlusion in one. No major abnormalities were seen in extracranial cerebral vasculature in 15 patients. Transesophageal echocardiograms in 11 patients showed a patent foramen ovale in one patient but no systemic source of embolism. Seven patients had non-central nervous system thrombotic events. CONCLUSION: Patients with APC resistance and stroke appear to differ from the general stroke population in terms of age and frequency of extracranial sources of cerebrovascular disease.

Increased rate of factor V Leiden mutation in patients with cerebral venous thrombosis.

We investigated the association between cerebral venous thrombosis and hereditary resistance to activated protein C (APC) in 12 consecutive German patients with non-fatal cerebral venous thrombosis and in 187 controls without a history of thrombotic disorder. Three patients (25%) had a mutation in the factor V Leiden gene against only one subject in the control group. This difference was significant (P < 0.05), with an odds ratio of 11.7 (1.5-87; 95% confidence interval). Two patients carrying the mutation had additional common risk factors for thrombosis, and 2 had a positive family history of thromboembolism. We conclude that inherited APC resistance by a mutation in factor V Leiden is an important risk factor in non-fatal cerebral venous thrombosis. We recommend testing for APC resistance and, if abnormal for factor V Leiden mutation in patients with cerebral venous thrombosis.