Small deep infarcts (SDI), also called lacunar infarcts, resulting from the occlusion of deep branch arteries, account for 25% of ischemic strokes. The physiopathology of the disease remains largely ...unknown. However, evidence about the role of endothelial dysfunction has emerged. Whereas chronic platelet activation is of major importance in acute thrombosis of large atherosclerotic arteries, its role in SDI remains unclear. Frequently associated risk factors are hypertension and diabetes mellitus. The aim of this study was to determine platelet and endothelial activation in patients with recent SDI in comparison to population-based control subjects matched for age, sex and vascular risk factors.
Platelet activation markers (activated glycoprotein IIb/IIIa, P-selectin and platelet microparticles), shear-induced platelet aggregation (SIPA) studied in the SIPAgreg device at 4,000 s(-1), endothelial activation markers including von Willebrand factor (vWF) antigen and homocysteine and high-sensitivity C-reactive protein (hsCRP) were measured in 74 consecutive patients with recent SDI, in whom detectable large artery atherosclerosis or cardiac embolism had been ruled out. Blood samples were collected 1 and 3 months after symptom onset. These factors were also measured in 74 population-based controls with no stroke history and matched for age, sex, hypertension and diabetes.
One month after symptom onset, the patients had similar levels of platelet activation to matched controls (p > 0.40 for all comparisons). In contrast, endothelial activation parameters were increased in patients in comparison to controls (vWF: p = 0.002 and homocysteinemia/creatinemia: p = 0.025). The level of hsCRP was slightly increased in patients compared to controls (p = 0.059). At 3 months, we observed a significant decrease in vWF and hsCRP levels in patients (median change in vWF = 10%, p = 0.004; median change in hsCRP = 0.4 mg/l, p = 0.02). Homocysteine levels and all platelet parameters remained unchanged at this time compared to at 1 month.
Our results confirm that chronic platelet activation, when compared to controls matched for age, sex and vascular risk factors, did not seem to play a central role in the pathophysiology of lacunar stroke. In contrast, we found markers of endothelial dysfunction, the role of which in the occurrence of lacunar infarction has still to be clarified in further studies.
Background
Bleeding originating in the gastrointestinal (
GI
) tract is one of the most common adverse events after left ventricular assist device (
LVAD
) implantation. In these patients,
GI
...bleeding appears to be the consequence of altered hemostasis on the one hand and alterations of the
GI
microvasculature on the other.
Case Report
We report the case of a patient who suffered repeated, severe
GI
bleeding early after implantation of a
HeartMate II
continuous‐flow
LVAD
.
Results
After failure of conventional treatment strategies,
GI
bleeding was controlled using repeated transfusions of a purified von
W
illebrand factor (
VWF
) concentrate, almost devoid of
F
actor
VIII
(
W
ilfactin,
LFB
). No episodes of pump thrombosis were noted. Subsequent to
VWF
transfusions, we observed a progressive normalization of circulating vascular endothelial growth factor levels.
Conclusions
Our data raise the possibility that, in addition to its hemostatic properties, transfusions of
VWF
might have acted as an antiangiogenic factor.
Background: Myeloproliferative neoplasms (MPN) are associated with an increased risk of arterial and venous thrombosis with an annual incidence varying from 1.1% to 6.6% (Patrono, Blood 2013). ...Comparable to that recommended in non-MPN high-risk patients, low-dose aspirin (81-100 mg/day) is recommended in primary and secondary prophylaxis of thrombosis in polycythemia vera and essential thrombocytemia (Tefferi, Am J Hematol 2012). However, the daily dose of aspirin to optimize efficacy and safety for MPN patients has never been challenged.
Aim of the study: Determine the optimal dose of aspirin to achieve biological efficacy in Philadelphia-negative MPN patients.
Methods: Patients with Philadelphia-negative MPN who were treated with low-dose aspirin 75 or 100 mg/day were enrolled in this observational study. Patients without any cytostatic drug and patients treated with either pegylated interferon alpha or hydroxyurea were eligible. Major exclusion criteria included inability to adhere to aspirin therapy and chronic oral anticoagulation. Biological efficacy to aspirin was evaluated by platelet aggregation induced by arachidonic acid 1.33 mM on platelet rich plasma and tested at trough level and 24 hours after last aspirin intake. Resistance to aspirin was defined as a maximal platelet aggregation over 20%. According to the results of platelet aggregation, aspirin dose and dosing regimen were modified as follows: from 100 mg/day to 160 mg/day or 75 mg x2/day. Patients enrolled in this have a median follow up of at least 6 months after the analysis.
Results: Between January 2012 and February 2014, 77 patients with Philadelphia-negative MPN were included. 53 were treated with aspirin 75 mg/day (69%) and 24 with aspirin 100 mg/day (31%).
Out of the 53 patients treated with aspirin 75 mg/day, 12 patients (23%) were resistant to aspirin.
Resistance to aspirin was not correlated to sex, age, presentation, JAK2 status, treatment, history of thrombotic or bleeding and hematologic values (see following table). Table 1:The MPN Grade 1 Fibrosis PhenotypePMF (N:33)PV/ET (N:58)Total (N:91)Median age63 yrs55 yrs58 yrsSex1:31:11:2JAK V617F +16/33: (49%)40/58: (69%)56/91: (62%)Median Hgb(g/dL)11.9 (range 7.9-16.4)12.5 (range 8.0-19.8)12.2 (range 7.9-19.8)Median WBC(X10 (9))26.9 (range 1.3-188)8.9 (range 3.5-51.3)10.8 (range 1.3-188 )Median Platelet(X10 (9))179 (range 18.0-1194)505 (range 67-2286)370 (range 18-2286)Leukoerythroblastic Blood Smear15/33 (45%)PV: 17 ET: 5 Total: 22/58 (38%)37/91 (41%)Splenomegaly(cm below costal margin)18/33: (55%) Median: 1025/58: (43%) Median: 643/91(48%) Median: 4Transfusion dependence6/33: (18%)2/58: (4%)8/91: (9%)Presence Of ³ 1 symptom17/33: (52%)33/58: (57%)50/91: (55%)DIPSS risk intermediate 2 or higher13/33: (39%)17/58: (29%)30/91: (33%)2 or more prior therapies9/33: (27%)36/58: (62%)45/91: (49%)Vital Status (Alive)25/33: (76%)53/58: (91%)78/90: (86%)Median follow up time (yrs)1.9 (range 0.1-9.8)5.7 (range 0-34.5)3.1 (range 0-34.5)
An increased dose of 100 mg/day for at least 7 days overcame this biological resistance in 8 out of 8 re-tested patients. The 2 remaining 75mg resistant patients received an increased dose of aspirin but were not retested.
Out of the 24 patients under 100 mg/day, only two (8%) were resistant to aspirin. In these patients, increasing the dose to 160 mg/day did not modify their biological response. However a 75 mgx2 /day was effective to overcome biological resistance.
No thrombotic or bleeding event was observed during the 6-month follow-up regardless of the aspirin dose.
Conclusions: This is the first study to measure in standardized conditions the biological resistance of aspirin in 77 well-characterized Philadelphia-negative MPN patients. Although this does not reach statistical significance a higher proportion of patients treated with aspirin 75mg/day was resistant to anti-platelet therapy compared to patients treated with aspirin 100 mg/day. Increasing the dose of aspirin from 75 to 100 mg once daily overcomes this biological resistance without increasing bleeding side effects and seems the best compromise. Interestingly in rare cases of extreme resistance to 100mg doubling the dose twice daily (75mgX2) was better than an increase of 160mg in one take. This pilot study on a small number of patients with a limited 6-month follow up compared to the low annual incidence of thromboses in these MPNs will be followed by a prospective study on a larger number of patients with an extended follow-up period to determine if biological resistance to aspirin is correlated to the occurrence of thrombotic events.
No relevant conflicts of interest to declare.
•JAK2V617F mutation contributes to hemorrhagic lesions and to mortality in an experimental model of cerebral venous thrombosis.•JAK2V617F mutation exacerbates thromboinflammatory response during ...cerebral venous thrombosis.
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Cerebral venous sinus thrombosis (CVST) is an uncommon venous thromboembolic event accounting for <1% of strokes resulting in brain parenchymal injuries. JAK2V617F mutation, the most frequent driving mutation of myeloproliferative neoplasms, has been reported to be associated with worse clinical outcomes in patients with CVST. We investigated whether hematopoietic JAK2V617F expression predisposes to specific pathophysiological processes and/or worse prognosis after CVST. Using an in vivo mouse model of CVST, we analyzed clinical, biological, and imaging outcomes in mice with hematopoietic-restricted Jak2V617F expression, compared with wild-type Jak2 mice. In parallel, we studied a human cohort of JAK2V617F-positive or -negative CVST. Early after CVST, mice with hematopoietic Jak2V617F expression had increased adhesion of platelets and neutrophils in cerebral veins located in the vicinity of CVST. On day 1, Jak2V617F mice had a worse outcome characterized by significantly more frequent and severe intracranial hemorrhages (ICHs) and higher mortality rates. Peripheral neutrophil activation was enhanced, as indicated by higher circulating platelet–neutrophil aggregates, upregulated CD11b expression, and higher myeloperoxydase plasma level. Concurrently, immunohistological and brain homogenate analysis showed higher neutrophil infiltration and increased blood-brain barrier disruption. Similarly, patients with JAK2V617F-positive CVST tended to present higher thrombotic burden and had significantly higher systemic immune-inflammation index, a systemic thromboinflammatory marker, than patients who were JAK2V617F-negative. In mice with CVST, our study corroborates that Jak2V617F mutation leads to a specific pattern including increased thrombotic burden, ICH, and mortality. The exacerbated thromboinflammatory response, observed both in mice and patients positive for JAK2V617F, could contribute to hemorrhagic complications.
We aimed to determine if elevations in serum neuron-specific enolase are associated with brain injury and outcomes in adults who require venoarterial extracorporeal membrane oxygenation.
Prospective ...observational study.
Two ICUs of a university hospital, Paris, France.
Consecutive adult patients treated with venoarterial extracorporeal membrane oxygenation for refractory cardiogenic shock or in-hospital refractory cardiac arrest.
None.
Serum sampled 1, 3, and 7 days after venoarterial extracorporeal membrane oxygenation cannulation was stored at -80°C and neuron-specific enolase concentrations were measured in batches at the end of the study. The association between neuron-specific enolase concentrations and outcomes (28-d mortality and poor outcome, defined by a score of 4-6 on the modified Rankin scale at 90 d) were explored by multivariable logistic regression, with neuron-specific enolase concentrations dichotomized according to median values. One-hundred three patients were included, of whom 26 (25%) received preextracorporeal membrane oxygenation cardiopulmonary resuscitation. Median (interquartile range) day-1, day-3, and day-7 neuron-specific enolase serum concentrations were 37 μg/L (26-51 μg/L), 25 μg/L (19-37) μg/L, and 22 μg/L (17-31 μg/L). After adjustment for Simplified Acute Physiology Score II, preextracorporeal membrane oxygenation cardiopulmonary resuscitation, and Sepsis Organ Failure Assessment score at time of cannulation, a day-3 neuron-specific enolase greater than 25 μg/L remained independently associated with 28-day mortality (adjusted odds ratio, 4.98; 95% CI, 1.86-13.32) and poor outcome at 90 days (adjusted odds ratio, 4.63; 95% CI, 1.81-11.84). A day-3 neuron-specific enolase threshold greater than 80 μg/L had a 100% specificity for prediction of both mortality (95% CI, 92-100%) and poor functional outcome (95% CI, 89-100%). In a subset of patients who underwent brain CT, neuron-specific enolase concentrations were significantly higher in patients diagnosed with stroke, as compared with those without stroke.
In adult patients under venoarterial extracorporeal membrane oxygenation, day-3 serum neuron-specific enolase concentrations are independently associated with short-term mortality and poor functional outcomes. These findings deserve validation in a multicenter setting.
Abstract Introduction The polysaccharide fraction from the skin of the ray Raja radula was extracted, characterized and assayed for anticoagulant activity. Materials and methods A whole ...polysaccharidic fraction was extracted from the skin of the ray Raja radula by papain digestion followed by cetylpyridinium chloride and ethanol precipitation and was subjected to gel chromatography and anion exchange chromatography, acetate cellulose electrophoresis and characterized by physicochemical procedures. APTT and anti Xa assays were performed to assess the anticoagulant activity of the polysaccharidic fractions in comparison with unfractionated heparin. Results Gel and anion-exchange chromatography revealed two negatively charged polysaccharidic populations different in both molecular weight and charge. Infrared spectra suggested the occurrence of uronic acids and acetylated hexosamines. The second polysaccharide was highly sulfated, with a sulfate content of approximately 29%. These data suggested that dermatan sulfate (DS) is the sulfate rich polysaccharide whereas hyaluronic acid (HA) is the polysaccharide devoid of sulfate groups. Molecular mass characterization indicated that their average molecular masses were 22 kDa and 85 kDa, respectively. The sulfated polysaccharide, i.e. presumably DS, accounted alone for the observed concentration-dependent anticoagulant activity which was, as measured by APTT, 2 to 3-fold lower than that of heparin. In addition, it had a significant anti-Xa activity. Conclusion A major-sulfated polysaccharide, likely a dermatan sulfate, was extracted from the ray Raja radula skin. The results indicated that it exhibited a high anticoagulant activity and suggested that it was mediated by both heparin cofactor II and antithrombin.
The aim of our study was to characterise heparin-binding properties of mutated von Willebrand factor (VWF) in 24 patients plasmas with type 2 von Willebrand disease (VWD). and in 15 recombinant VWF ...(rVWF) with the corresponding mutations. Binding of mutated rVWF or plasma VWF was compared to that of WT-rVWF or normal pool plasma VWF. Four mutations, at positions C509, V551, R552 and R611 lead to significantly decreased binding to heparin in both plasma and rVWF. Interestingly, whereas these four residues are distant in the primary structure of VWF-A1domain, they are close to each other in its three-dimensional structure. Structural analysis suggested how folding problems and destabilisation due to these mutations could induce reorganisation of surface regions involved in heparin binding. In contrast, no heparin-binding defect was found associated with different type 2 VWF mutants, at positions G561, E596, I662, R543, R545, V553, R578 or L697.
The dermatan sulfate (DS) isolated from the ray skin
Raja montagui was identified and characterized. Its average molecular weight (Mw) and sulfate content were 39
kDa and 25% w/w, respectively. This ...DS prolonged thrombin time and activated partial thromboplastin time and inhibited the thrombin generation in a concentration-dependent manner whereas it had no effect on the anti-Xa assay and on platelet function. Data from the anti-IIa assay allowed the assessment of the specific anticoagulant activity which was 40
units/mg. The kinetics of the thrombin inhibition by heparin cofactor II (HCII) has been studied as a function of DS concentration according to a kinetic model in which the polysaccharide binds quickly to the inhibitor and forms a complex more reactive than the free inhibitor towards thrombin. This DS accelerated thrombin inhibition exclusively by HCII. The dissociation constant of the DS–HCII complex,
K
DSHCII, and the rate constant of the thrombin inhibition by this complex,
k, were (2.93
±
0.25)
×
10
−
6
M and (2.2
±
0.35)
×
10
9M
−
1
min
−
1
, respectively.
Our findings indicated that the major polysaccharide in the skin of the ray
Raja montagui was a DS endowed with a high anticoagulant effect mediated by HCII and which may constitute an anticoagulant drug of interest in anticoagulant therapy.
Abstract 3194
In the blood, platelets are normally prevented from activation by endothelial inhibitors (i.e. prostacycline, ectonucleotidase). Dysfunctional endothelial cells loose their protective ...properties and favor platelet adhesion to matrix proteins, platelet aggregation and thrombus growth. Collagen fibers are highly thrombogenic and the platelet Glycoprotein (GP)VI predominantly mediates collagen-induced platelet responses. GPVI is a platelet specific receptor of the immunoglobulin (Ig) superfamily containing two extracellular Ig domains, a single transmembrane domain and a short cytoplasmic tail. GPVI signals through the immunoreceptor tyrosine-based activation motifs (ITAM) of the non-covalently associated immune receptor adaptor FcRg dimer. There is growing evidence that optimal binding of GPVI to collagen depends on the formation of GPVI dimers at the platelet surface: only dimeric GPVI binds to collagen and inhibits collagen-induced platelet aggregation and not monomeric GPVI. Moreover, crystallographic data showed dimerization of GPVI ectodomains. However, the valence of GPVI on resting and activated platelets is still debated.
We have obtained an anti-human GPVI monoclonal antibody (9E18), that binds to dimeric GPVI with a 200 fold higher affinity than to monomeric GPVI. In flow cytometry on whole blood, while the 3J24 antibody labels >95% platelets, 9E18 hardly binds to resting platelets with less than 3% positive platelets. The level of 9E18-positive platelets moderately increased (10-15%) after platelet isolation suggesting it could reflect platelet activation. Binding of 9E18 was indeed significantly increased on ADP- or TRAP-activated washed platelets (25±1.9 % and 36±7% positive platelets respectively). Additionally, increased binding of 9E18 was triggered by the GPVI agonists, collagen, convulxin or the activating 9O12 IgG. At sites of vascular lesion, platelet adhesion is initiated by the shear-dependent interaction of GPIb with vWF, assumed to favor GPVI-collagen interaction. When a platelet rich plasma was submitted to a shear of 4000 s-1 for 5 min, 9E18-positive platelets increased from 3.6±1.6% to 7±2% in the whole platelet population and to 26±7.7% on small aggregates (p<0.05).When a2b1 and aIIbb3 were blocked, the relation between the 9E18 binding to stimulated platelets and platelet binding to collagen was linear (r2 = 0.847, p=0.0012, n=8). Interestingly, the cAMP elevating agent PGE1 further lowered the level of 9E18-binding to resting platelets and dropped it to basal values on ADP- or TRAP-treated platelets. Apyrase reduced by 50% TRAP-induced binding of 9E18 whereas indomethacin had no effect. PMA triggered binding of 9E18 on platelets (p<0.001) while the Tyr-phosphatase inhibitor PAO, strongly inhibited PMA-induced 9E18 binding to platelets (p<0.0019) and GPVI-dependent platelet adhesion to collagen.
Altogether, these data indicate that 9E18 permit to quantify GPVI dimers on platelets. They show that (i) GPVI is mainly monomeric on resting platelets, (ii) dimerisation is an active process triggered by shear, soluble agonists and matrix proteins, (iii) the level of GPVI dimers is related to the capacity of platelets to adhere to collagen, (iv) GPVI dimerisation is completely prevented in the presence of agents increasing cAMP or by PAO. These data suggested that the formation of GPVI dimer is strictly controlled on resting platelets and that GPVI dimers could thus represent a new marker of platelet activation and susceptibility to collagen. Indeed, in a population of hospitalized patient, a positive correlation was observed between 9E18 binding and P-selectin exposure on platelets.
No relevant conflicts of interest to declare.
Background: Idarucizumab has been included in guidelines for the management of bleeding or surgical procedure in dabigatran-treated patients without need for biological monitoring. The aim of the ...study was to assess the prognostic value of dabigatran plasma level before reversal to test the hemostatic efficacy of idarucizumab. The secondary objectives were (i) to analyze plasma dabigatran level according to the risk of rebound and (ii) to evaluate the incidence of post-reversal non-favorable clinical outcomes (including thromboembolism, bleeding, antithrombotic, and death) and antithrombotic resumption. Methods and Results: This was an observational multicentric cohort study, which included all French patients who required idarucizumab for dabigatran reversal. Between May 2016 and April 2019, 87 patients from 21 French centers were enrolled. Patients received idarucizumab for overt bleeding ( n = 61), urgent procedures ( n = 24), or overdose without bleeding ( n = 2). Among patients with major bleeding ( n = 57), treatment with idarucizumab was considered effective in 44 (77.2%) of them. Patients who did not achieve effective hemostasis after reversal had a significantly higher mean level of plasma dabigatran at baseline (524.5 ± 386 vs. 252.8 ng/mL ± 235, p = 0.033). Furthermore, patients who did not achieve effective hemostasis after reversal had less favorable outcomes during follow-up (46.2 vs. 81.8%, p = 0.027). ROC curve identified a cutoff of 264 ng/mL for dabigatran level at admission to be predictive of ineffective hemostasis. No plasma dabigatran rebound was observed after reversal in patients with dabigatran plasma level < 264 ng/mL at baseline. Conclusion: This retrospective study shows that dabigatran level before reversal could predict hemostatic effectiveness and dabigatran plasma rebound after idarucizumab injection.
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