Increased dipeptidyl peptidase-4 accelerates chronic stress-related thrombosis in a mouse carotid artery model.

OBJECTIVE: Exposure to chronic psychosocial stress is a risk factor for metabolic cardiovascular disorders. Given that dipeptidyl peptidase-4 (DPP-4) has an important role in human pathobiology, we investigated the role of DPP-4 in stress-related thrombosis in mice, focusing on oxidative stress and the von Willebrand factor (vWF)-cleaving protease ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13). METHODS AND RESULTS: Male mice randomly assigned to nonstress and 2-week immobilized-stress groups underwent iron chloride3 (FeCl3)-induced carotid artery thrombosis surgery for morphological and biochemical studies at specific times. On day 14 post-stress/surgery, stress had enhanced the lengths and weights of arterial thrombi, with alterations of plasma DPP-4, plasminogen activation inhibitor-1 and ADAMTS13. The stressed mice had increased levels of vascular cell adhesion molecule-1, intracellular adhesion molecule-1, monocyte chemoattractant protein-1, gp91phox, p22phox, matrix metalloproteinase-2 (MMP-2), MMP-9, cathepsins S and K mRNAs and/or proteins, and reduced levels of endothelial nitric oxide synthase, catalase and superoxide dismutase-1 mRNAs and/or proteins. Stress also accelerated arterial endothelial cell damage. The DPP-4 inhibitor anagliptin ameliorated the stress-induced targeted molecular and morphological changes and thrombosis. In vitro, DPP-4 inhibition also mitigated the alterations in the targeted ADAMTS13 and other oxidative and inflammatory molecules in human umbilical vein endothelial cells in response to H2O2. CONCLUSION: DPP-4 inhibition appeared to improve the FeCl3-induced thrombosis in mice that received stress, possibly via the improvement of ADAMTS13 and oxidative stress, suggesting that DPP-4 could become a novel therapeutic target for chronic psychological stress-related thrombotic events in metabolic cardiovascular disorders.

Predicting Clinical Outcome After Mechanical Thrombectomy: The GADIS (Gender, Age, Diabetes Mellitus History, Infarct Volume, and Current Smoker [corrected]) Score.

OBJECTIVE: To investigate predictive factors and develop an outcome assessment tool to determine clinical outcome after endovascular mechanical thrombectomy (EMT) in patients presenting with large vessel occlusion (LVO). METHODS: A retrospective analysis was carried out of a prospective cohort of patients presenting with LVO who underwent EMT after adoption of an expanded time window of ≤24 hours. Final cerebral infarction volume (CIV) after EMT was estimated using magnetic resonance imaging segmentation software. Stepwise linear regression models were used to identify factors that determined clinical outcome and to develop a predictive scale. RESULTS: Ninety patients underwent EMT over 19 months (68 within 6 hours and 22 between 6 and 24 hours). Clinical outcome determined using modified Rankin Scale (mRS) score at discharge and 3 months was no different among these subcohorts. A threshold of 16.99 mL of CIV, using the Youden index, resulted in a sensitivity of 90.5% and specificity of 58.1% for predicting mRS score of 0-2. A regression model identified gender, age, diabetes mellitus status, CIV, and smoking status as outcome determinants, which were used to develop the GADIS (Gender, Age, Diabetes Mellitus History, Infarct Volume, and Sex) scoring system to predict good clinical outcome. Using the GADIS score, <6 predicted mRS score 0-2 at discharge with a sensitivity of 83.3% and specificity of 80.6%. CONCLUSIONS: The GADIS score for patients with LVO-related acute ischemic stroke includes CIV after EMT and helps in early short-term prognostication. It is not intended to predict preintervention patient selection or outcome prediction.

Use of Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS) and Ischemic Core Volume to Determine the Malignant Profile in Acute Stroke.

Background Malignant profiles were identified by imaging profiles and unfavorable outcomes that have poor response to reperfusion therapy. Many trials have used this profile in their inclusion criteria including large-vessel occlusion acute ischemic stroke trials. We aimed to redefine the cutoff values for malignant profile in acute ischemic stroke patients with large-vessel occlusion regardless of reperfusion therapy. Methods and Results Consecutive acute ischemic stroke patients with anterior large-vessel occlusion were prospectively extracted from the National Cerebral and Cardiovascular Center Stroke Registry between March 2014 and December 2017. Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS) and diffusion-weighted imaging lesion ischemic core volume (VolDWI) were measured in acute ischemic stroke patients with large-vessel occlusion with or without treatment. Unfavorable outcome was defined as a modified Rankin Scale score 5 to 6 at 3 months, and optimal DWI-ASPECTS and VolDWI for unfavorable outcome were assessed. In total, 198 patients (111 men, 77±13 years old) were enrolled. Median DWI-ASPECTS was 7 (5-9), and median VolDWI was 55 (6-134) mL. Among the patients, 72 (36%) patients underwent reperfusion therapy, and 83 (42%) had unfavorable outcomes. The threshold values for a malignant profile on receiver operating characteristic curve analysis for DWI-ASPECTS and VolDWI were 4 (area under the curve 0.78, P<0.01; sensitivity 0.71, specificity 0.75) and 71 mL (area under the curve 0.80, P<0.01; sensitivity 0.76, specificity 0.77), respectively. Conclusions The cutoff values for our redefined malignant profile were DWI-ASPECTS 4 and VolDWI 71 mL with no selection bias for reperfusion therapy in the real-world clinical practice. Clinical Trial Registration URL: http://www.clinicaltrials.gov Unique identifier: NCT02251665.

Optimizing in-hospital triage for large vessel occlusion using a novel clinical scale (GAI2AA).

OBJECTIVE: To identify a proximal anterior circulation occlusion for effectively administering immediate mechanical thrombectomy by developing a novel, simple diagnostic scale to predict the occlusion, to compare its validity with available scales, and to assess its utility. METHODS: To develop a novel clinical scale, we retrospectively analyzed a cohort of 429 patients with acute ischemic stroke from a single center. The novel scale GAI2AA was applied to a prospective cohort of 259 patients from 3 stroke centers for external validation. The utility of the scale as an in-hospital triage was compared for the temporal factors of 158 patients with the occlusion. RESULTS: In a scale-developmental phase, those with a proximal anterior circulation occlusion had significantly more frequent signs of hemispheric symptoms, including gaze palsy, aphasia, inattention, arm paresis, and atrial fibrillation. The GAI2AA scale was developed using consolidated hemispheric symptoms and was scored as follows: score = 2, arm paresis score = 1, and atrial fibrillation score = 1. A cutoff value ≥3 was optimal for the correlation between sensitivity (88%) and specificity (81%), with a C statistic of 0.90 (95% confidence interval 0.87-0.93). External validation indicated that discrimination was significantly better than or not different from that of available complex scales. Door-to-puncture time was significantly reduced (91 [82-111] vs 52 [32-75] minutes, p < 0.001). CONCLUSION: The GAI2AA scale showed high sensitivity and specificity when an optimal cutoff score was used and was useful as an in-hospital triage tool.

Interventional recanalization as a treatment of carotid stump syndrome caused by right internal carotid artery occlusion: A case report.

RATIONALE: Carotid stump syndrome is a cerebral infarction caused by an embolus formed subsequent to the vortex of blood flow from the occluded stump, which then moves through the collateral vessels into the brain. The covered stent and stent-assisted coil embolization stump are the effective interventions for the carotid artery stump. PATIENT CONCERNS: A 71-year-old man twice experienced left limb weakness; diffusion weighted imaging confirmed the diagnosis of cerebral infarction. Cervical computed tomography angiography, intracranial magnetic resonance angiography, and digital subtraction angiography were conducted to evaluate collateral circulation, intraluminal composition, and shape of the carotid stump. DIAGNOSES: The patient was diagnosed with cerebral infarction and right carotid stump syndrome. INTERVENTION: The patient underwent interventional recanalization of the occluded internal carotid artery, which relieved his symptoms and led to satisfactory therapeutic outcomes during the clinical follow-up. OUTCOMES: A 9-month clinical follow-up revealed no stroke recurrence. LESSONS: Interventional recanalization for the carotid artery stump syndrome is feasible. Accurate preoperative evaluation including collateral circulation, intraluminal composition, and shape of the carotid stump can assure a successful vascularization and guided management.

Protective effects of gelsolin in acute pulmonary thromboembolism and thrombosis in the carotid artery of mice.

The present study provides first evidence on the role of plasma gelsolin in protecting pulmonary thromboembolism and thrombosis in a mouse model. Gelsolin is the most abundant actin depolymerizing protein in plasma and its significantly depleted values have been reported in metabolic disorders including cardiovascular diseases and myocardial infarction. Though gelsolin replacement therapy (GRT) has been shown to be effective in some animal models, no such study has been reported for thrombotic diseases that are acutely in need of bio-therapeutics for immediate and lasting relief. Here, using mice model and recombinant human gelsolin (rhuGSN), we demonstrate the antithrombotic effect of gelsolin in ferric chloride induced thrombosis in carotid artery and thrombin induced acute pulmonary thromboembolism. In thrombosis model, arterial occlusion time was significantly enhanced upon subcutaneous (SC) treatment with 8 mg of gelsolin per mice viz. 15.83 minutes vs. 8 minutes in the placebo group. Pertinently, histopathological examination showed channel formation within the thrombi in the carotid artery following injection of gelsolin. Fluorescence molecular tomography imaging further confirmed that administration of gelsolin reduced thrombus formation following carotid artery injury. In thrombin-induced acute pulmonary thromboembolism, mice pretreated with aspirin or gelsolin showed 100 and 83.33% recovery, respectively. In contrast, complete mortality of mice was observed in vehicle treated group within 5 minutes of thrombin injection. Overall, our studies provide conclusive evidence on the thrombo-protective role of plasma gelsolin in mice model of pulmonary thromboembolism and thrombosis.

Predictive value of transcranial evoked potentials during mechanical endovascular therapy for acute ischaemic stroke: a feasibility study.

BACKGROUND AND PURPOSE: Mechanical endovascular therapy (MET) is a promising adjuvant or stand-alone therapy for acute ischaemic stroke caused by occlusion of a large vessel. Real-time monitoring of recanalisation success with regard to functional outcome is usually not possible because these procedures are mainly performed under general anaesthesia. We present a novel application for evoked potential monitoring for real-time evaluation of reperfusion success with respect to functional outcome during MET for acute ischaemic stroke. METHODS: Prospective observational study from March 2012 to April 2013 of patients presenting with acute ischaemic stroke who were eligible for MET. Transcranial motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) were measured bilaterally during MET throughout the intervention. The electrophysiological data of the contralateral side served as control. Neurological outcome was assessed by the modified Rankin Scale and National Institutes of Health Stroke Scale at 0, 7 and 90 days following intervention. RESULTS: 20 patients were examined. MEPs and SSEPs were technically successful in 19 (95%) and 9 (45%) cases, respectively. Successful reperfusion was achieved in 16 cases. Functional recovery was observed in 14 patients. MEPs and SSEPs recovery status was a better predictor of functional recovery than successful reperfusion with a positive predictive value of 92%, 83% and 75% for MEPs, SSEPs and reperfusion, respectively. CONCLUSIONS: MEPs and SSEPs are safe and feasible methods of real-time monitoring of reperfusion success with respect to functional outcome during MET for acute ischaemic stroke.

Direct interaction of kindlin-3 with integrin αIIbß3 in platelets is required for supporting arterial thrombosis in mice.

OBJECTIVE: Kindlin-3 is a critical supporter of integrin function in platelets. Lack of expression of kindlin-3 protein in patients impairs integrin αIIbß3-mediated platelet aggregation. Although kindlin-3 has been categorized as an integrin-binding partner, the functional significance of the direct interaction of kindlin-3 with integrin αIIbß3 in platelets has not been established. Here, we evaluated the significance of the binding of kindlin-3 to integrin αIIbß3 in platelets in supporting integrin αIIbß3-mediated platelet functions. APPROACH AND RESULTS: We generated a strain of kindlin-3 knockin (K3KI) mice that express a kindlin-3 mutant that carries an integrin-interaction defective substitution. K3KI mice could survive normally and express integrin αIIbß3 on platelets similar to their wild-type counterparts. Functional analysis revealed that K3KI mice exhibited defective platelet function, including impaired integrin αIIbß3 activation, suppressed platelet spreading and platelet aggregation, prolonged tail bleeding time, and absence of platelet-mediated clot retraction. In addition, whole blood drawn from K3KI mice showed resistance to in vitro thrombus formation and, as a consequence, K3KI mice were protected from in vivo arterial thrombosis. CONCLUSIONS: These observations demonstrate that the direct binding of kindlin-3 to integrin αIIbß3 is involved in supporting integrin αIIbß3 activation and integrin αIIbß3-dependent responses of platelets and consequently contributes significantly to arterial thrombus formation.

Mechanical thrombectomy with Solitaire stent for acute internal carotid artery occlusion without atherosclerotic stenosis: dissection or cardiogenic thromboembolism.

BACKGROUND: In acute ischemic stroke patients, internal carotid artery occlusion with middle cerebral artery (ICA/MCA) occlusion in succession predicts a poor outcome after systemic thrombolysis. It is not known whether this occlusion subtype of the anterior circulation is due to dissections or cardiogenic thromboembolism. We aimed to find useful evidence to judge the condition with accuracy and establish reasonable treatment protocols. PATIENTS AND METHODS: This retrospective study included 7 consecutive patients with acute ICA/MCA occlusion in succession who had undergone mechanical thrombectomy with a Solitaire stent retrieval between January 2012 and June 2013. Then we also reviewed the current literature. RESULTS: The patients had a mean age of 56 years and a mean baseline National Institutes of Health Stroke Scale (NIHSS) score of 20. The procedure resulted in thrombolysis in cerebral ischemia (TICI) scores of 2a or better in all patients, but complete recanalization of the ICA occlusion segment was achieved in only 2 patients. Stenting was not performed in all patients. At 90 days, 1 patient was dead and 4 of the 7 patients had favorable functional outcomes (modified Rankin score (mRS) ≥ 2). We identified 9 studies with 85 patients with nonatherosclerotic acute ICA occlusion who underwent mechanical thrombectomy with Solitaire stent. The mean age was 65 years with a mean baseline National Institute Health Stroke Scale (NIHSS) score of 16 and mean time to treatment of 242 minutes. The mean time of the procedures ranged from 40-160 minutes in 9 studies. Successful recanalization was achieved in 69.4% of the patients and mortality was 16.5%. Favorable outcome (mRS ≤ 2) occurred in 42.4% of patients. Few studies stated whether complete recanalization was achieved in patients with ICA occlusion. CONCLUSIONS: Our results and the literature review suggest that mechanical thrombectomy in acute stroke due to ICA/MCA occlusion is feasible and safe, with high rates of recanalization and favorable functional outcomes. More patients with ICA/MCA occlusion in succession could obtain favorable functional outcomes with accurate judgment of the lesion location and appropriate treatment protocols. However, there is no consensus on how to judge the correct location of the ICA dissected portion and whether stenting is appropriate.

Detection of activated platelets in a mouse model of carotid artery thrombosis with 18 F-labeled single-chain antibodies.

INTRODUCTION: Activated platelets are key players in thrombosis and inflammation. We previously generated single-chain antibodies (scFv) against ligand-induced binding sites (LIBS) on the highly abundant platelet glycoprotein integrin receptor IIb/IIIa. The aim of this study was the construction and characterisation of a novel (18)F PET radiotracer based on this antibody. METHODS: ScFv(anti-LIBS) and control antibody mut-scFv were reacted with N-succinimidyl-4-[(18)F]fluorobenzoate (S[(18)F]FB). Radiolabeled scFv was incubated with in vitro formed platelet clots and injected into mice with FeCl(3) induced thrombus in the left carotid artery. Clots were imaged in the PET scanner and amount of radioactivity measured using an ionization chamber and image analysis. Assessment of vessel injury as well as the biodistribution of the radiolabeled scFv was studied. RESULTS: After incubation with increasing concentrations of (18)F-scFv(anti-LIBS) clots had retained significantly higher amounts of radioactivity compared to clots incubated with radiolabeled (18)F-mut-scFv (13.3 ± 3.8 vs. 3.6 ± 1 KBq, p < 0.05, n = 9, decay corrected). In the in vivo experiments we found an high uptake of the tracer in the injured vessel compared with the non-injured vessel, with 12.6 ± 4.7% injected dose per gram (ID/g) uptake in the injured vessel and 3.7 ± 0.9% ID/g in the non-injured vessel 5 minutes after injection (p < 0.05, n = 6). CONCLUSIONS: Our results show that the novel antibody radiotracer (18)F-scFv(anti-LIBS) is useful for the sensitive detection of activated platelets and thrombosis. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: We describe the first (18)F variant of a scFv(anti-LIBS) against activated platelets. This diagnostic agent could provide a powerful tool for the assessment of acute thrombosis and inflammation in patients in the future.

Comparison of cognitive performance between two rat models of vascular dementia.

BACKGROUND AND PURPOSE: An ideal animal model to explore that pathogenesis and prevention of dementia is essential. The present study was designed to compare the difference of behavior and cerebral blood flow of the two vascular dementia rat models at different time intervals. METHODS: The rats were randomly allocated to three groups: bilateral common carotid artery occlusion (BCCAO) group, thromboembolism (TE) group and sham-operated (SHAM) group. The performance in the Morris water maze (MWM) was analyzed at 7, 14 and 28 d after operation and cerebral blood flow (CBF) was analyzed at 28 days after operation. RESULT: The results showed that the two models exhibited longer latency, less times to crossing platform in MWM and lower CBF than the SHAM rats. Compared with the TE rats, the BCCAO rats have a significant prolongation of escape latency at 7 days and 28 days. In the probe trial, the BCCAO rats showed less number of times across the platform. CONCLUSION: The BCCAO rats maybe provide a more useful model to study the physiopathological mechanisms of cognitive impairment related to chronic cerebral ischemia.

Iridoid glycosides extracted from zhizi (fructus gardeniae) decrease collagen-induced platelet aggregation and reduce carotid artery thrombosis in an in vivo rat model.

OBJECTIVE: To investigate the anti-platelet aggregation and antithrombotic effects in rats of iridoid glycosides extracted from Zhizi (Fructus Gardeniae). METHODS: The present study evaluated the antithrombotic activity of iridoid glycosides (IGs) in a rat model of carotid artery thrombosis. The effects on coagulation, such as thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT), and the effect on collagen-induced platelet aggregation in vivo were investigated. Rats were intragastrically administered IGs (50, 100 or 200 mg/ kg) twice daily for 3 days. RESULTS: IGs were shown for the first time to have an antithrombotic action through the inhibition of platelet aggregation, with little effect on the coagulation time of peripheral blood. Our results also showed that IGs may significantly and dose-dependently reduce arterial thrombus load in a model of carotid artery thrombosis and inhibit collagen-induced platelet aggregation in rats. IGs (100 or 200 mg/kg) had no significant effect on APTT and PT, but did lengthen TT at a higher dose. CONCLUSION: These data, together with the previously reported neuroprotective effects of IGs in rats with cerebral ischemia, suggest that the antithrombotic action of IGs may potentially contribute to the treatment of cerebral ischemic diseases, including cerebral apoplexy.

Spontaneous free floating carotid artery thrombosis.

A 64-year-old man, with no history of trauma, presented with transient visual loss. He was diagnosed with amaurosis fugax and started on dipyridamole and simvastatin. An inconclusive ultrasound (US) Doppler was followed by CT angiogram (CTA) and MRI, which demonstrated free floating intraluminal thrombus in the distal right common carotid artery. ECG showed sinus rhythm and an echocardiogram showed no cardiac thrombus. Following discussion at the vascular multidisciplinary team the decision was made to treat with intravenous heparin followed by warfarin. He has been regularly followed up with CTA/USS, the most recent (Oct 2012) showing no evidence of thrombus. He has had no further symptoms. Despite no initial aetiology being found we suggest that his undiagnosed oesophageal carcinoma (diagnosed 5 months after initial presentation) could have been responsible for a hypercoagulability state giving an increased risk of thrombosis and leading to the thrombus in the common carotid artery.

[Intracranial aneurysms and epilepsy]. / Aneurismas intracraneales y epilepsia.

TITLE: Aneurismas intracraneales y epilepsia.

α(1,3)-Fucosyltransferases FUT4 and FUT7 control murine susceptibility to thrombosis.

The α(1,3)-fucosyltransferases, types IV and VII (FUT4 and FUT7, respectively), are required for the synthesis of functional selectin-type leukocyte adhesion molecule ligands. The selectins and their ligands modulate leukocyte trafficking, and P-selectin and its ligand, P-selectin glycoprotein ligand-1, can modulate hemostasis and thrombosis. Regulation of thrombosis by FUT4 and/or FUT7 activity was examined in mouse models of carotid artery thrombosis and collagen/epinephrine-induced thromboembolism. Mice lacking both FUT4 and FUT7 (Fut(-/-) mice) had a shorter time to occlusive thrombus formation in the injured carotid artery and a higher mortality due to collagen/epinephrine-induced pulmonary thromboemboli. Mice lacking P-selectin or P-selectin glycoprotein ligand-1 did not have a prothrombotic phenotype. Whole blood platelet aggregation was enhanced, and plasma fibrinogen content, clot weight, and clot strength were increased in Fut(-/-) mice, and in vitro clot lysis was reduced compared with wild type. Fut4(-/-), but not Fut7(-/-), mice had increased pulmonary thromboembolism-induced mortality and decreased thromboemboli dissolution in vivo. These data show that FUT4 and FUT7 activity regulates thrombosis in a P-selectin- and P-selectin glycoprotein ligand-1-independent manner and suggest that FUT4 activity is important for thrombolysis.

Atherosclerotic geometries exacerbate pathological thrombus formation poststenosis in a von Willebrand factor-dependent manner.

Rupture of a vulnerable atherosclerotic plaque causes thrombus formation and precipitates cardiovascular diseases. In addition to the thrombogenic content of a plaque, also the hemodynamic microenvironment plays a major role in thrombus formation. How the altered hemodynamics around a plaque promote pathological thrombus formation is not well understood. In this study, we provide evidence that plaque geometries result in fluid mechanical conditions that promote platelet aggregation and thrombus formation by increased accumulation and activity of von Willebrand factor (vWF) at poststenotic sites. Resonant-scanning multiphoton microscopy revealed that in vivo arterial stenosis of a damaged carotid artery markedly increased platelet aggregate formation in the stenotic outlet region. Complementary in vitro studies using microfluidic stenotic chambers, designed to mimic the flow conditions in a stenotic artery, showed enhanced platelet aggregation in the stenotic outlet region at 60-80% channel occlusion over a range of input wall shear rates. The poststenotic thrombus formation was critically dependent on bloodborne vWF and autocrine platelet stimulation. In stenotic chambers containing endothelial cells, flow provoked increased endothelial vWF secretion in the stenotic outlet region, contributing to exacerbated platelet aggregation. Taken together, this study identifies a role for the shear-sensitive protein vWF in transducing hemodynamic forces that are present around a stenosis to a prothrombogenic microenvironment resulting in spatially confined and exacerbated platelet aggregation in the stenosis outlet region. The developed stenotic microfluidic chamber offers a realistic platform for in vitro evaluation of shear-dependent thrombus formation in the setting of atherosclerosis.

The cell motility modulator Slit2 is a potent inhibitor of platelet function.

BACKGROUND: Vascular injury and atherothrombosis involve vessel infiltration by inflammatory leukocytes, migration of medial vascular smooth muscle cells to the intimal layer, and ultimately acute thrombosis. A strategy to simultaneously target these pathological processes has yet to be identified. The secreted protein, Slit2, and its transmembrane receptor, Robo-1, repel neuronal migration in the developing central nervous system. More recently, it has been appreciated that Slit2 impairs chemotaxis of leukocytes and vascular smooth muscle cells toward diverse inflammatory attractants. The effects of Slit2 on platelet function and thrombus formation have never been explored. METHODS AND RESULTS: We detected Robo-1 expression in human and murine platelets and megakaryocytes and confirmed its presence via immunofluorescence microscopy and flow cytometry. In both static and shear microfluidic assays, Slit2 impaired platelet adhesion and spreading on diverse extracellular matrix substrates by suppressing activation of Akt. Slit2 also prevented platelet activation on exposure to ADP. In in vivo studies, Slit2 prolonged bleeding times in murine tail bleeding assays. Using intravital microscopy, we found that after mesenteric arteriolar and carotid artery injury, Slit2 delayed vessel occlusion time and prevented the stable formation of occlusive arteriolar thrombi. CONCLUSIONS: These data demonstrate that Slit2 is a powerful negative regulator of platelet function and thrombus formation. The ability to simultaneously block multiple events in vascular injury may allow Slit2 to effectively prevent and treat thrombotic disorders such as myocardial infarction and stroke.

Repeated doses of oral and subcutaneous heparins have similar antithrombotic effects in a rat carotid arterial model of thrombosis.

Although heparins are usually injected intravenously or subcutaneously, antithrombotic activity is observed in rat models following single oral heparin doses. Since repetitive dosing is usually needed for thromboprophylaxis, study objectives were to determine whether repetitive oral heparin prevented arterial thrombosis and to compare effectiveness to subcutaneous administration. Wistar rats were given subcutaneous or oral unfractionated heparin ([UFH] 1 mg/kg per 48 h), low-molecular-weight heparin ([LMWH] tinzaparin, 0.1 mg/kg per 12 h), or saline for 30 days. On the last day, thrombosis was initiated by placing 30% FeCl(3)-soaked filter paper on the distal carotid. Subsequent flow measurements, for a 60-minute period, included recorded time of initial thrombus formation (time till thrombus begins [TTB]), and time until carotid occlusion (time till occlusion [TTO]). The formed thrombus was dried and weighed. The activated partial thromboplastin time (aPTT), anti-factor Xa, and antithrombin activity were determined from the plasma. Both oral and subcutaneous heparins significantly increased TTB and TTO. Time of initial thrombus formations were 12.6 ± 1.1, 21.2 ± 2.2, 25.3 ± 3.9, 21.7 ± 3.1, and 21.3 ± 1.7 minutes and TTOs were 29.3 ± 3.6, 54.8 ± 4.0, 60.0 ± 0.3, 56.7 ± 3.3, and 58.3 ± 1.7 minutes (mean ± SEM) for control, subcutaneous UFH, oral UFH, subcutaneous LMWH, and oral LMWH, respectively. Thrombus weight was 2.52 ± 0.29 g in control and was reduced to 43%, 23%, 33%, and 28% of control weight for subcutaneous UFH, oral UFH, subcutaneous LMWH, and oral LMWH, respectively. Thrombus weight was significantly less for oral compared to subcutaneous UFH. The aPTT for oral UFH, and anti-factor Xa activity in the LMWH-treated groups were significantly greater than control (two-tailed t tests). These findings confirm that orally administered heparins are absorbed. Repeated treatment with oral heparin showed similar antithrombotic activity compared to subcutaneous heparin. Oral heparin use for arterial thromboprophylaxis should be further investigated.

A malignant case of acute promyelocytic leukemia with occlusion of carotid artery by tumor thrombus.

We report an unusual and malignant presentation of acute promyelocytic leukemia (APL) resulting in thrombosis of a cervicocephalic artery by tumor in a healthy 37-year-old woman. The patient's rapid decline and multiorgan involvement proved to be a diagnostic and therapeutic challenge, and despite the efforts of a coordinated multidisciplinary health care team, she suffered a cardiac arrest and died within 48 hours of presentation to the emergency department. Autopsy revealed an APL-related tumor thrombus obstructing the left internal carotid artery, which to the best of our knowledge has not yet been described as a cause of fatal stroke.