Synergistic effect of collagen and CXCL12 in the low doses on human platelet activation.

CXCL12, also known as stromal cell-derived factor-1, is a chemokine classified into CXC families, which exerts its function by binding to specific receptors called CXCR4 and CXCR7. Human platelets express CXCR4 and CXCR7 on the plasma membrane. It has been reported that CXCL12 potentiates to induce platelet aggregation in cooperation with agonists including collagen. However, the precise roles and mechanisms of CXCL12 in human platelet activation are not fully elucidated. In the present study, we investigated the effect of simultaneous stimulation with low doses of collagen and CXCL12 on the activation of human platelets. The simultaneous stimulation with collagen and CXCL12 induced the secretion of platelet-derived growth factor (PDGF)-AB and the release of soluble CD40 ligand (sCD40L) from human platelets in addition to their aggregation, despite the fact that the simultaneous stimulation with thrombin receptor-activating peptide (TRAP) or adenosine diphosphate (ADP), and CXCL12 had little effects on the platelet aggregation. The agonist of Glycoprotein (GP) Ⅵ convulxin and CXCL12 also induced platelet aggregation synergistically. The monoclonal antibody against CXCR4 but not CXCR7 suppressed the platelet aggregation induced by simultaneous stimulation with collagen and CXCL12. The phosphorylation of p38 mitogen-activated protein kinase (MAPK), but not p44/p42 MAPK, was induced by the simultaneous stimulation. In addition, the simultaneous stimulation with collagen and CXCL12 induced the phosphorylation of HSP27 and the subsequent release of phosphorylated-HSP27 from human platelets. SB203580, a specific inhibitor of p38 MAPK, attenuated the platelet aggregation, the phosphorylation of p38 MAPK and HSP27, the PDGF-AB secretion, the sCD40L release and the phosphorylated-HSP27 release induced by the simultaneous stimulation with collagen and CXCL12. These results strongly suggest that collagen and CXCL12 in low doses synergistically act to induce PDGF-AB secretion, sCD40L release and phosphorylated-HSP27 release from activated human platelets via p38 MAPK activation.

[A Case Report of Surgical Resection of a Supraseller Granuloma in a Patient with Erdheim-Chester Disease].

Erdheim-Chester disease(E-CD)is a rare pathology characterized by systematic granulomatosis that occasionally involves the central nervous system. We report about a 68-year-old woman with E-CD who presented with right-side visual disturbance. Magnetic resonance imaging showed a suprasellar tumor that elevated the right optic nerve and involved the right internal carotid and right anterior choroidal arteries. The tumor was partially resected via a trans-Sylvian approach and was histologically diagnosed as a granuloma. Considering the abnormal findings of postoperative X-ray and 99 mTc bone scintigraphy of the long bones, the pathology was diagnosed as E-CD. After surgery, her right-side visual disturbances disappeared. However, 1 year later, she died of systemic infection and heart failure. Histological autopsy findings indicated numerous yellowish nodules in the heart, lung, and kidney with pericardial and pleural effusions and whole-body granulomatosis, including the brain. E-CD is a rare but critical disease. This pathological entity should be considered when encountering cases of intracranial granuloma to ensure its early diagnosis and appropriate treatment. Surgical resection of intracranial granulomas in patients with E-CD may promptly improve neurological dysfunction.

Smoking cessation affects human platelet activation induced by collagen.

It is firmly established that smoking is a risk factor of cardiovascular disease, stroke and peripheral vascular disease. Although smoking alters the hemostatic process, the influence of smoking on human platelet activation remains controversial. For patients undergoing surgery, cessation of smoking prior to the procedure is recommended as it increases the risk of postoperative morbidity or mortality. The presented study investigated the effects of smoking cessation on human platelet activation induced via collagen (n=19 patients). Blood samples were taken on four occasions: Before smoking cessation, and at 4, 8 and 12 weeks after smoking cessation. Platelet aggregation using citrated platelet-rich plasma (PRP) was monitored using a PA-200 aggregometer, which determined the size of platelet aggregates using laser scattering methods. A low dose of collagen (1 µg/ml) accelerated platelet aggregation at 4 or 8 weeks after smoking cessation when compared with results before cessation. After 12 weeks, levels of platelet aggregation induced by collagen were almost equal to those recorded prior to smoking cessation. The secretion levels of collagen-induced platelet-derived growth factor (PDGF)-AB at 4 or 8 weeks after smoking cessation were significantly higher than those before smoking was stopped. Furthermore, smoking cessation markedly strengthened the collagen-induced phosphorylation of p38 mitogen-activated protein (MAP) kinase after 4 weeks. The results of the current study indicated that smoking cessation causes temporary short-term human platelet hyper-activation. The further suggest that the incidence of complications due to human platelet hyper-reactivity may be lowered by considering the period of smoking abstinence.

[A Case of Glioblastoma that Appeared One Year after the Removal of Subcortical Hematoma].

Subcortical bleeding from brain tumors is not rare. In the majority of cases, tumors are revealed within a few months after bleeding. We herein report a relatively rare case of glioblastoma(GBM)that appeared one year after the removal of a subcortical hematoma. A 70-year-old woman suddenly began experiencing headache, vomiting, and aphasia. CT revealed a subcortical hematoma in the left superior temporal lobe and subarachnoid bleeding. Neither aneurysms nor abnormal signs suggesting a malignant tumor were noted during cerebral angiography. The hematoma was completely removed via craniotomy, and she was discharged with no neurological deficit.(MRI performed seven months after the surgery showed neither space-occupying lesions in the left temporal lobe nor brain edema. Twelve months after the initial surgery, she had aphasia again. CT and MRI revealed an enhanced mass lesion in the left temporal lobe. Positron emission tomography findings strongly indicated the presence of a malignant tumor. Histology of the tumor after removal showed GBM HDH-1 wild-type with an MIB-1 labelling index of approximately 50%. After the surgery, she underwent extensive local radiation therapy(50 Gy)with chemotherapy(temozolomide). The pathological mechanism underlying the appearance of GBM at the site where subcortical bleeding was previously observed is unclear. GBM may have caused bleeding or may have originated from the brain tissue that was damaged during the first surgery. Follow-up using neuroimaging for one year may be needed when subcortical bleeding is observed.

Rac Regulates the TRAP-Induced Release of Phosphorylated-HSP27 from Human Platelets via p38 MAP Kinase but Not JNK.

BACKGROUND/AIMS: Thrombin induces the activation of human platelets through protease-activated receptor (PAR) 1 and PAR4, and Rac, a member of the Rho family of small GTPases, is implicated in PAR activation. We previously reported that phosphorylated-heat shock protein 27 (HSP27) is released from the thrombin receptor-activating peptide (TRAP)-stimulated platelets of diabetic patients. In the present study, we investigated the role of Rac in the TRAP-elicited release of phosphorylated-HSP27 from human platelets. METHODS: Platelet aggregation was measured using an aggregometer with laser scattering. Protein phosphorylation was analyzed by Western blotting. The levels of phosphorylated-HSP27 and platelet-derived growth factor-AB (PDGF-AB) were measured by enzyme-linked immunosorbent assays. RESULTS: NSC23766, an inhibitor of Rac-guanine nucleotide exchange factor interaction, suppressed the TRAP-elicited release of phosphorylated-HSP27 as well as platelet aggregation. The TRAP-induced phosphorylation of HSP27, p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) was attenuated by NSC23766. SB203580, a p38 MAPK inhibitor, but not SP600125, a JNK inhibitor, suppressed the release of phosphorylated-HSP27 in addition to HSP27 phosphorylation. On the other hand, both SB203580 and SP600125 reduced the TRAP-stimulated secretion of PDGF-AB. CONCLUSION: Our results strongly suggest that Rac acts as a positive regulator of the PAR-elicited release of phosphorylated-HSP27 from human platelets via p38 MAPK but not JNK.

Tailored Strategies in Carotid Artery Stenting to Avoid Periprocedural Complications.

Carotid artery stenting (CAS) has been widely accepted as a valuable therapeutic alternative to carotid endarterectomy (CEA) for high-grade carotid stenosis. Because carotid revascularization including CAS is usually performed in patients with minimal or no neurological deficits, utmost care should be taken to avoid periprocedural complications. The major concerns associated with CAS are embolic stroke, hyperperfusion syndrome (HPS), and perioperative myocardial infarction.Plaque characteristics, cerebral blood flow (CBF) in the affected cerebral hemisphere, and concomitant coronary artery disease prior to CAS are all important to assess the risks of these complications and are routinely evaluated.Tailored CAS is planned based on findings of preoperative evaluation, as follows. (1) If the plaque component is thought vulnerable, proximal embolic protection methods, use of a closed-cell-type stent, or referral to CEA should be considered to avoid embolic complications. (2) If patients have severe CBF impairment, staged angioplasty is an effective strategy to prevent postoperative HPS. (3) If concomitant cardiac diseases are present, the optimal treatment sequence should be discussed between cardiologists and neurointerventionalists.These tailored strategies based on preoperative risk evaluations may lead to safer procedures and better clinical outcome in CAS patients.

Optimal platelet function test for in-stent tissue protrusion following carotid artery stenting.

Purpose To determine the best platelet function test for in-stent tissue protrusion following carotid artery stenting (CAS). Methods Patients who underwent CAS were recruited prospectively in this observational study. Combination of aspirin 100 mg/day and clopidogrel 75 mg/day was administered for a minimum of 7 days prior to procedure. Platelet aggregation was measured by light transmittance aggregometry (LTA) following stimulation by adenosine diphosphate (ADP), collagen, and thrombin receptor activating peptide (TRAP) and by the point of care assay, VerifyNow which measures aspirin and thienopyridine reaction units. Results In-stent tissue protrusion with maximum projection area of ≥1 mm2 was detected by optical coherence tomography (OCT) in 10/28 (36%) patients. Baseline characteristics were not significantly different between the two in-stent size groups (i.e., ≥1 mm2 vs. <1 mm2) but after stimulation by collagen at 10 and 20 µg/ml, platelet reactivity as measured by LTA was significantly higher in the ≥1 mm2 group compared with the <1 mm2 group. No other differences in platelet function were detected. Conclusions Collagen-induced platelet reactivity was related to in-stent tissue protrusion size following CAS.

Sphingosine 1-phosphate (S1P) suppresses the collagen-induced activation of human platelets via S1P4 receptor.

Sphingosine 1-phosphate (S1P) is as an extracellular factor that acts as a potent lipid mediator by binding to specific receptors, S1P receptors (S1PRs). However, the precise role of S1P in human platelets that express S1PRs has not yet been fully clarified. We previously reported that heat shock protein 27 (HSP27) is released from human platelets accompanied by its phosphorylation stimulated by collagen. In the present study, we investigated the effect of S1P on the collagen-induced platelet activation. S1P pretreatment markedly attenuated the collagen-induced aggregation. Co-stimulation with S1P and collagen suppressed collagen-induced platelet activation, but the effect was weaker than that of S1P-pretreatment. The collagen-stimulated secretion of platelet-derived growth factor (PDGF)-AB and the soluble CD40 ligand (sCD40L) release were significantly reduced by S1P. In addition, S1P suppressed the collagen-induced release of HSP27 as well as the phosphorylation of HSP27. S1P significantly suppressed the collagen-induced phosphorylation of p38 mitogen-activated protein kinase. S1P increased the levels of GTP-bound Gαi and GTP-bound Gα13 coupled to S1PPR1 and/or S1PR4. CYM50260, a selective S1PR4 agonist, but not SEW2871, a selective S1PR1 agonist, suppressed the collagen-stimulated platelet aggregation, PDGF-AB secretion and sCD40L release. In addition, CYM50260 reduced the release of phosphorylated-HSP27 by collagen as well as the phosphorylation of HSP27. The selective S1PR4 antagonist CYM50358, which failed to affect collagen-induced HSP27 phosphorylation, reversed the S1P-induced attenuation of HSP27 phosphorylation by collagen. These results strongly suggest that S1P inhibits the collagen-induced human platelet activation through S1PR4 but not S1PR1.

Cilostazol ameliorates collagenase-induced cerebral hemorrhage by protecting the blood-brain barrier.

Intracranial hemorrhage remains a devastating disease. Among antiplatelet drugs, cilostazol, a phosphodiesterase 3 inhibitor, was recently reported to prevent secondary hemorrhagic stroke in patients in a clinical trial. The aim of this study was to evaluate whether pre-treatment with cilostazol could decrease the intracranial hemorrhage volume and examine the protective mechanisms of cilostazol. We evaluated the pre-treatment effects of the antiplatelet drug cilostazol on the collagenase-induced intracranial hemorrhage volume and neurological outcomes in mice. To estimate the mechanism of collagenase injury, we evaluated various vascular components in vitro, including endothelial cells, vascular smooth muscle cells, pericytes, and a blood-brain barrier model. Cilostazol pre-treatment reduced the intracranial hemorrhage volume with sufficient inhibition of platelet aggregation, and motor function was improved by cilostazol treatment. Blood-brain barrier permeability was increased by collagenase-induced intracranial hemorrhage, and cilostazol attenuated blood-brain barrier leakage. Terminal deoxynucleotidyl transferase dUTP nick-end labeling and western blot analysis showed that cilostazol prevented pericyte cell death by inducing cyclic adenosine monophosphate-responsive element-binding protein phosphorylation. Cilostazol also prevented endothelial cell death and protected collagen type 4, laminin, and vascular endothelial- and N-cadherins from collagenase injury. In conclusion, cilostazol reduced collagenase-induced intracranial hemorrhage volume by protecting the blood-brain barrier.

Diabetes mellitus and carotid artery plaques exhibiting high-intensity signals on MR angiography are related to increased platelet reactivity after carotid artery stenting.

BACKGROUND: Increased platelet reactivity after carotid artery stenting (CAS) may cause thromboembolic complications. OBJECTIVE: This study aimed to investigate the incidence of increased platelet reactivity after CAS and to determine the factors related to it. METHODS: Patients who underwent CAS were recruited prospectively. They received pre-procedural antiplatelet therapy comprising some combination of aspirin (100 mg/day), clopidogrel (75 mg/day), and/or cilostazol (200 mg/day) for a minimum of 7 days. ADP- and collagen-induced platelet aggregation were measured before and 4 days after CAS. Changes in platelet reactivity were reported as changes in the categorized platelet reactivity grade based on the effective dose 50%. Clinical characteristics of patients with and without increased platelet reactivity were compared. RESULTS: Among 38 consecutive patients who underwent CAS, 18 (47%) exhibited increased platelet reactivity. Diabetes mellitus (OR 15.0; 95% CI 2.1 to 106.5; p=0.007) and carotid artery plaques exhibiting high-intensity signals (HIS) on time-of-flight MR angiography (TOF-MRA) (OR 25.2; 95% CI 2.0 to 316.2; p=0.013) were independently associated with increased platelet reactivity in a multivariate analysis. CONCLUSIONS: Increased platelet reactivity occurred in nearly half of the studied patients subjected to CAS and was independently associated with diabetes mellitus and carotid artery plaques exhibiting HIS on TOF-MRA.

AICAR reduces the collagen-stimulated secretion of PDGF-AB and release of soluble CD40 ligand from human platelets: Suppression of HSP27 phosphorylation via p44/p42 MAP kinase.

We have previously reported that collagen-induced phosphorylation of heat shock protein (HSP) 27 via p44/p42 mitogen-activated protein (MAP) kinase in human platelets is sufficient to induce the secretion of platelet-derived growth factor (PDGF)-AB and the release of soluble cluster of differentiation 40 ligand (sCD40L). Adenosine monophosphate-activated protein kinase (AMPK), which is known to regulate energy homeostasis, has a crucial role as an energy sensor in various eukaryotic cells. The present study investigated the effects of 5-aminoimidazole-4-carboxamide-1-ß-d-ribofuranosyl 5'-monophosphate (AICAR), which is an activator of AMPK, on the collagen-induced activation of human platelets. It was demonstrated that AICAR dose-dependently reduced collagen-stimulated platelet aggregation up to 1.0 µM. Analysis of the size of platelet aggregates demonstrated that AICAR decreased the ratio of large aggregates (50-70 µm), whereas the ratio of small aggregates (9-25 µm) was increased by AICAR administration. AICAR markedly attenuated the phosphorylation levels of p44/p42 MAP kinase and HSP27, which are induced by collagen. Furthermore, AICAR significantly decreased the secretion of PDGF-AB and the collagen-induced release of sCD40L. These results indicated that AICAR-activated AMPK may reduce the secretion of PDGF-AB and the collagen-induced release of sCD40L by inhibiting HSP27 phosphorylation via p44/p42 MAP kinase in human platelets.

Thrombin Receptor-Activating Protein (TRAP)-Activated Akt Is Involved in the Release of Phosphorylated-HSP27 (HSPB1) from Platelets in DM Patients.

It is generally known that heat shock protein 27 (HSP27) is phosphorylated through p38 mitogen-activated protein (MAP) kinase. We have previously reported that HSP27 is released from human platelets associated with collagen-induced phosphorylation. In the present study, we conducted an investigation into the effect of thrombin receptor-activating protein (TRAP) on the release of HSP27 in platelets in type 2 diabetes mellitus (DM) patients. The phosphorylated-HSP27 levels induced by TRAP were directly proportional to the aggregation of platelets. The levels of phosphorylated-HSP27 (Ser-78) were correlated with the levels of phosphorylated-p38 MAP kinase and phosphorylated-Akt in the platelets stimulated by 10 µM TRAP but not with those of phosphorylated-p44/p42 MAP kinase. The levels of HSP27 released from the TRAP (10 µM)-stimulated platelets were correlated with the levels of phosphorylated-HSP27 in the platelets. The released platelet-derived growth factor-AB (PDGF-AB) levels were in parallel with the HSP27 levels released from the platelets stimulated by 10 µM TRAP. Although the area under the curve (AUC) of small aggregates (9-25 µm) induced by 10 µM TRAP showed no significant correlation with the released HSP27 levels, AUC of medium aggregates (25-50 µm), large aggregates (50-70 µm) and light transmittance were significantly correlated with the released HSP27 levels. TRAP-induced phosphorylation of HSP27 was truly suppressed by deguelin, an inhibitor of Akt, in the platelets from a healthy subject. These results strongly suggest that TRAP-induced activation of Akt in addition to p38 MAP kinase positively regulates the release of phosphorylated-HSP27 from human platelets, which is closely related to the platelet hyper-aggregation in type 2 DM patients.

Factor Xa Inhibitor Suppresses the Release of Phosphorylated HSP27 from Collagen-Stimulated Human Platelets: Inhibition of HSP27 Phosphorylation via p44/p42 MAP Kinase.

Selective inhibitors of factor Xa (FXa) are widely recognized as useful therapeutic tools for stroke prevention in non-valvular atrial fibrillation or venous thrombosis. Thrombin, which is rapidly generated from pro-thrombin through the activation of factor X to FXa, acts as a potent activator of human platelets. Thus, the reduction of thrombin generation by FXa inhibitor eventually causes a suppressive effect on platelet aggregation. However, little is known whether FXa inhibitors directly affect the function of human platelets. We have previously reported that collagen induces the phosphorylation of heat shock protein 27 (HSP27), a low-molecular weight heat shock protein via Rac-dependent activation of p44/p42 mitogen-activated protein (MAP) kinase in human platelets, eventually resulting in the release of HSP27. In the present study, we investigated the direct effect of FXa inhibitor on the collagen-induced human platelet activation. Rivaroxaban as well as edoxaban significantly reduced the collagen-induced phosphorylation of both HSP27 and p44/p42 MAP kinase without affecting the platelet aggregation. Rivaroxaban significantly inhibited the release of phosphorylated HSP27 from collagen-stimulated platelets but not the secretion of platelet derived growth factor-AB. In patients administrated with rivaroxaban, the collagen-induced levels of phosphorylated HSP27 were markedly diminished after 2 days of administration, which failed to affect the platelet aggregation. These results strongly suggest that FXa inhibitor reduces the collagen-stimulated release of phosphorylated HSP27 from human platelets due to the inhibition of HSP27 phosphorylation via p44/p42 MAP kinase.

Delayed Stenosis in the Intracranial Vessels following Endovascular Treatment for Acute Stroke.

PURPOSE: To evaluate delayed stenosis of the vessels after endovascular thrombectomy using magnetic resonance (MR) angiography. MATERIALS AND METHODS: Of 82 consecutive patients who underwent successful endovascular treatment for acute intracranial large vessel occlusion between October 2010 and October 2014 at a single institution, 57 patients for whom 3-month radiologic follow-up examinations using MR angiography were available were included in the analysis. MR angiography images were assessed to detect delayed stenosis, which was defined as a decrease in the diameter of treated vessels > 50% compared with MR angiography images obtained 24 hours after endovascular treatment. RESULTS: MR angiography images obtained 3 months after endovascular treatment revealed delayed stenosis of treated vessels in five (8.8%) of 57 patients. All cases of delayed stenosis were asymptomatic and occurred in the middle cerebral artery (MCA). Further serial radiologic follow-up showed gradual improvement of all delayed stenosis over 12 months. CONCLUSIONS: Endovascular treatment poses a risk of delayed stenosis of treated vessels, especially in the MCA. MR angiography is a useful modality in long-term follow-up to evaluate delayed stenosis after endovascular treatment.

Release of Phosphorylated HSP27 (HSPB1) from Platelets Is Accompanied with the Acceleration of Aggregation in Diabetic Patients.

We investigated the relationship between HSP27 phosphorylation and collagen-stimulated activation of platelets in patients with diabetes mellitus (DM). Platelet-rich plasma was prepared from blood of type 2 DM patients. The platelet aggregation was analyzed in size of aggregates by an aggregometer using a laser scattering method. The protein phosphorylation was analyzed by Western blotting. Phosphorylated-HSP27 and PDGF-AB released from platelets were measured by ELISA. The phosphorylated-HSP27 levels at Ser-78 and Ser-82 induced by collagen were directly proportional to the platelet aggregation. Total HSP27 levels in platelets were decreased concomitantly with the phosphorylation. The released HSP27 levels were significantly correlated with the phosphorylated levels of HSP27 in the platelets stimulated by 0.3 µg/ml collagen. The low dose collagen-stimulated release of HSP27 was detected but relatively small in healthy donors. The released levels of PDGF-AB were in parallel with the levels of released HSP27. Area under the curve (AUC) of small aggregation (9-25 µm) induced by 0.3 µg/ml collagen was inversely proportional to the levels of released HSP27. AUC of large aggregation (50-70 µm) was directly proportional to the levels of released HSP27. Exogenous recombinant phosphorylated- HSP27 hardly affected the aggregation or the released levels of PDGF-AB induced by collagen. These results strongly suggest that HSP27 is released from human platelets accompanied with its phosphorylation induced by collagen, which is correlated with the acceleration of platelet aggregation in type 2 DM patients.

αB-crystallin reduces ristocetin­induced soluble CD40 ligand release in human platelets: suppression of thromboxane A2 generation.

Our group has previously shown that αB-crystallin (HSPB5), a small heat shock protein, inhibits human platelet aggregation by ristocetin, an activator of glycoprotein Ib/IX/V. In addition, it was demonstrated that glycoprotein Ib/IX/V activation induces soluble CD40 (sCD40) ligand release via thromboxane (TX) A2. In the present study, the effect of αB-crystallin on the ristocetin-induced sCD40 ligand release in human platelets was investigated. The ristocetin-induced release of sCD40 ligand was suppressed by αB-crystallin. In addition, αB-crystallin reduced the ristocetin-stimulated production of 11-dehydro-TX B2, a stable metabolite of TXA2. αB-crystallin did not suppress the platelet aggregation induced by U46619, a TXA2 receptor agonist. αB-crystallin had little effect on the U46619-induced phosphorylation of p38 mitogen-activated protein kinase or sCD40 ligand release. In addition, αB-crystallin failed to reduce the binding of SZ2, a monoclonal antibody against the sulfated sequence in the α-chain of glycoprotein Ib, to the ristocetin-stimulated platelets. These results strongly suggest that αB-crystallin extracellularly suppresses ristocetin-stimulated release of sCD40 ligand by inhibiting the TXA2 production in human platelets.

Preliminary experience with air transfer of patients for rescue endovascular therapy after failure of intravenous tissue plasminogen activator.

The present report describes our experience with air transfer of patients with acute ischemic stroke in whom intravenous tissue plasminogen activator (IV t-PA) failed for rescue endovascular therapy (EVT). Twenty-three consecutive patients in whom IV t-PA failed were transferred to our hospital for rescue EVT between February 2011 and April 2013. The amount of time required for transfer, distance, clinical outcomes, and complications were compared between patients transferred by ground (TG group; n = 17) and by air (TA group; n = 6). Computed tomography imaging on arrival revealed hemorrhagic transformation in 1 (5.9%) patient in the TG group, whereas none of the patients in the TA group developed any type of complication. The remaining 22 patients received rescue EVT. The elapsed time from the request call to arrival at our hospital did not significantly differ between the TG and TA groups (45.8 ± 4.9 min vs. 41.6 ± 2.3 min). However, the distance from the primary hospital to our institution was significantly longer for the TA group than for the TG group (38.8 ± 10.4 km vs. 13.5 ± 1.2 km, p = 0.001). The frequency of favorable outcomes (modified Rankin Scale 0-1 at 90 days after onset) in the TG and TA groups were 25.0% and 50.0%, respectively (p = 0.267). Air transfer for patients after IV t-PA failure allowed for more rapid delivery of patients over longer distances than ground transfer.

Rho-kinase regulates human platelet activation induced by thromboxane A2 independently of p38 MAP kinase.

We have previously demonstrated that ristocetin, an activator of GPIb/IX/V, induces the release of soluble CD40 ligand (sCD40L) via thromboxane A2 production in human platelets. It has been shown that thromboxane A2 induces the activation of Rho-kinase, a downstream effector of Rho, in human platelets. In the present study, we investigated the exact roles of Rho-kinase in thromboxane A2-induced platelet activation. We found that U46619, a thromboxane receptor (TP) agonist, induced the phosphorylation of cofilin, a target of Rho-kinase signaling, and that the cofilin phosphorylation by U46619 was suppressed by Y27632 or fasudil, specific inhibitors of Rho-kinase. Y27632 and fasudil markedly decreased large platelet aggregate formation by U46619. The release of sCD40L and secretion of platelet-derived growth factor (PDGF)-AB stimulated by U46619 were inhibited by Y27632 and fasudil. SB203580, a specific inhibitor of p38 mitogen-activated protein (MAP) kinase, reduced the sCD40L release and PDGF-AB secretion. Y27632 and fasudil failed to affect the phosphorylation of p38 MAP kinase whereas SB203580 had little effect on the phosphorylation of cofilin induced by U46619. In conclusion, our results strongly suggest that Rho-kinase regulates thromboxane A2-induced human platelet activation independently of p38 MAP kinase.

Long-term magnetic resonance angiography follow-up for recanalized vessels after mechanical thrombectomy.

BACKGROUND: Mechanical thrombectomy is an effective revascularization therapy for acute intracranial large vessel occlusion. We retrospectively evaluated magnetic resonance angiography (MRA) follow-up data to assess the long-term patency of recanalized vessels after mechanical thrombectomy. METHODS: We retrospectively reviewed medical records of consecutive patients who had undergone mechanical thrombectomy for intravenous tissue plasminogen activator-failed/ineligible acute intracranial major vessel occlusion between October 2010 and April 2013 at our institution. MRA follow-up was performed at baseline and at 24 ± 6 hours and 3 months after mechanical thrombectomy. RESULTS: Forty-nine patients underwent mechanical thrombectomy for acute intracranial major vessel occlusion. Mean age was 69.7 ± 11.5 years, and baseline median National Institute of Health Stroke Scale score was 15 (range, 8-24). Occlusion was found in the internal carotid artery in 18 patients (36.7%), middle cerebral artery in 26 patients (53%), and vertebral-basilar arteries in 5 patients (10.2%). Successful recanalization, as defined by a thrombolysis in cerebral infarction flow grade of 2b or 3, was achieved in 40 patients (81.6%). MRA follow-up at 24 hours after the treatment revealed that reocclusion of recanalized vessels was observed in 3 of 38 patients (7.9%). Long-term MRA follow-up showed that 2 of 27 patients (8.3%) developed diffuse severe stenosis of treated vessels. Both the patients had undergone treatment for middle cerebral artery occlusion with the Merci retriever and had been administered only anticoagulants, but not any antiplatelets. CONCLUSIONS: Reocclusion or late stenosis of successfully recanalized vessels was observed in 16.2% of patients. Long-term MRA follow-up of recanalized vessels will be useful, in particular, for the patient with middle cerebral artery occlusion who undergoes mechanical thrombectomy.

STA-MCA/STA-PCA Bypass Using Short Interposition Vein Graft.

BACKGROUND AND AIMS: Superficial temporal artery (STA) is the mainstay of donor vessels for extra-intracranial bypass (EC-IC bypass) in cerebral revascularization. However, the typically used STA frontal or parietal branch is not always adequate in its flow-carrying capacity. In the present study, we provide an update on an alternative strategy: the use of the STA main trunk as a donor vessel, with a short vein interposition graft. METHODS: Seven patients in whom the STA main trunk was used as a donor site for anastomosis of a short interposition vein graft were included. The grafts were implanted into the M2 of the middle cerebral artery for adjunctive treatment of IC anterior wall blood-blister aneurysms in two patients, for revascularization of an internal carotid artery occlusion in one patient, into the P2/3 of the posterior cerebral artery (PCA) for adjunct treatment of complex PCA aneurysms in three patients and into the P3 of PCA for adjunct treatment of basilar artery (BA) trunk giant aneurysm in one patient. RESULTS: All the bypasses were patent. Intraoperative flow measurements confirmed a moderate flow-carrying capacity of the STA main trunk-interposition short vein graft (20-50 ml; mean 43 ml/min). CONCLUSION: The STA main trunk has a larger diameter than the distal branch; therefore, it would be expected to have a significantly higher flow capacity than its branches. STA main trunk to proximal MCA/PCA bypass using short interposition vein grafts can provide sufficient blood flow, and may be a reasonable alternative to ECA to MCA/PCA bypass using long vein grafts.