Shohei Yokoyama

L3/Lhx8 is involved in the determination of cholinergic or GABAergic cell fate

The LIM homeobox family of transcription factors is involved in many processes during the development of the mammalian central nerves system. L3, also called Lhx8 (L3/Lhx8), is a recently identified member of the LIM homeobox gene family and is selectively expressed in the medial ganglionic eminence (MGE). Our previous study demonstrated that L3/Lhx8‐null mice specifically lacked cholinergic neurons in the basal forebrain. In this study, we reduced L3/Lhx8 function in the murine neuroblastoma cell line, Neuro2a (N2a), using L3/Lhx8‐targeted small interfering RNA (siRNA) produced by H1.2 promoter‐driven vector. The levels of cholinergic markers per cell were diminished without a reduction in the number of marker‐positive cells. Intriguingly, GABAergic marker expression and the number of GABAergic cells were dramatically increased in the differentiating L3/Lhx8‐knockdown N2a. These results suggest the possibility that L3/Lhx8 is involved in the determination of transmitter phenotypes (GABAergic or cholinergic cell fate) in a population of neurons during basal forebrain development.

L3/Lhx8 is a pivotal factor for cholinergic differentiation of murine embryonic stem cells.

L3/Lhx8 is a member of the LIM-homeobox gene family. Previously, we demonstrated that L3/Lhx8-null mice specifically lacked cholinergic neurons in the basal forebrain. In the present study, we conditionally suppressed L3/Lhx8 function during retinoic acid-induced neural differentiation of a murine embryonic stem (ES) cell line using an L3/Lhx8-targeted small interfering RNA (siRNA) produced by an H1.2 promoter-driven vector. Our culture conditions induced efficient differentiation of the ES cells into neurons and astrocytes, but far less efficient differentiation into oligodendrocytes. Suppression of L3/Lhx8 expression by siRNA led to a dramatic decrease in the number of cells positive for the cholinergic marker ChAT, and overexpression of L3/Lhx8 recovered this effect. However, no significant changes were observed in the number of Tuj1+ neurons and GABA+ cells. These results strongly suggest that L3/Lhx8 is a key factor in the cholinergic differentiation of murine ES cells and is involved in basal forebrain development.

Influence of Diabetes Mellitus and Cigarette Smoking on Variability of the Clopidogrel-Induced Antiplatelet Effect and Efficacy of Active Management of the Target P2Y12 Reaction Unit Range in Patients Undergoing Neurointerventional Procedures

BACKGROUND Optimal antiplatelet inhibition is essential in patients undergoing neurointerventional procedures; however, variability in response to clopidogrel can contribute to thromboembolic and hemorrhagic complications. The present study evaluated the influence of diabetes mellitus and cigarette smoking on clopidogrel reactivity. METHODS Between 2011 and 2013, 71 consecutive patients underwent aneurysmal coil embolization (CE) or carotid artery stenting (CAS) and received clopidogrel (75 mg daily) and aspirin (100 mg daily) before the treatment. The patients were divided into 2 groups: CE (n = 31) and CAS (n = 40). The patients underwent prospective assessment of preoperative platelet function using VerifyNow assay and received adjunctive cilostazol (200 mg daily, triple antiplatelet therapy) in case of clopidogrel hyporesponse. Patients with clopidogrel hyper-response underwent clopidogrel dose reduction (clopidogrel, 12.5-50 mg daily). RESULTS Clopidogrel resistance was noted in 15 patients (37.5%) in the CAS group and in 4 patients (12.9%) in the CE group (P = .031). Clopidogrel hyper-response was noted in 2 patients (5%) in the CAS group and in 11 patients (54.8%) in the CE group (P < .001). There was a significant difference in the baseline clinical characteristics between the 2 groups. In the multivariate logistic regression analysis, diabetes and age were independent predictors of clopidogrel hyporesponse, whereas current smoker was an independent predictor of clopidogrel hyper-response. CONCLUSIONS Significant differences in baseline clinical characteristics were present when comparing patients undergoing endovascular treatment of unruptured cerebral aneurysms and carotid artery stenosis. Diabetes mellitus and current smoker status were independent factors related to reactivity to clopidogrel.

Knockdown of the L3/Lhx8 gene suppresses cholinergic differentiation of murine embryonic stem cell-derived spheres

L3/Lhx8, a member of the Lim‐homeobox gene family, is selectively and specifically expressed in the murine embryonic medial ganglionic eminence (MGE). Our previous study demonstrated that L3/Lhx8‐deficient mice specifically lack cholinergic neurons in the basal forebrain. In this manuscript, we report the in vitro effects of reduced L3/Lhx8 gene expression on cholinergic differentiation in murine embryonic stem (ES) cell‐derived spheres without dissociation. The knockdown of L3/Lhx8 gene expression dramatically decreased the cholinergic phenotype of spheres without altering other known phenotypes (TuJ1, GABA and GFAP). These results strongly suggest that L3/Lhx8 is a key factor for cholinergic differentiation of murine ES cell‐derived spheres and is involved in basal forebrain development.

Indocyanine green kinetics with near-infrared spectroscopy predicts cerebral hyperperfusion syndrome after carotid artery stenting

Background Cerebral hyperperfusion syndrome (HPS) is a potentially life-threatening complication following carotid artery stenting (CAS) and carotid endoarterectomy (CEA). Early prediction and treatment of patients at risk for HPS are required in patients undergoing CAS because HPS occurs significantly earlier after CAS than CEA. Near-infrared spectroscopy (NIRS) is often used for monitoring, and indocyanine green (ICG) kinetics by NIRS (ICG-NIRS) can detect reductions in cerebral perfusion in patients with acute stroke. However, whether ICG-NIRS can predict postoperative hyperperfusion phenomenon (HP) after carotid revascularization is unclear. Objective Here, we evaluated whether the blood flow index (BFI) ratio calculated from a time-intensity curve from ICG-NIRS monitoring can predict HPS after CAS. Methods The BFI ratio was prospectively monitored using ICG-NIRS in 135 patients undergoing CAS. Preoperative cerebrovascular reactivity (CVR) and the postoperative asymmetry index (AI) were also assessed with single-photon emission computed tomography before and after CAS, and the correlation was evaluated. In addition, patients were divided into two groups, a non-HP group (n = 113) and an HP group (n = 22), and we evaluated the correlation with hemodynamic impairment in the ipsilateral hemisphere and clinical results. Results Twenty-two cases (16%) showed HP, and four (3%) showed HPS after CAS. The BFI ratio calculated from ICG-NIRS showed a significant linear correlation with preoperative CVR and postoperative AI (r = −0.568, 0.538, P < 0.001, <0.001, respectively). The degree of stenosis, the rate of no cross flow, preoperative CVR, and the incidence of HPS were significantly different between the groups. Conclusions Measurement of ICG kinetics by NIRS is useful for detection of HPS in patients who underwent CAS.

Efficacy of cilostazol-based dual antiplatelet treatment in patients undergoing carotid artery stenting

Abstract Background: It is essential that patients undergoing carotid artery stenting (CAS) receive optimal antiplatelet inhibition. Although a reduction in platelet reactivity and improved clinical outcomes occur when using adjunctive cilostazol with dual antiplatelet therapy, this can lead to an increased risk of hemorrhagic complications. Therefore, our current study examined patients undergoing CAS and evaluated the impact of cilostazol-based dual antiplatelet treatment on the outcomes. Methods: Between 2010 and 2015, 137 consecutive patients underwent CAS. From 2010 to 2011 (period 1), 28 patients underwent CAS in conjunction with aspirin and clopidogrel dual antiplatelet treatment (DAPT). From 2010 to 2013 (period 2), 44 patients underwent a preoperative assessment of their platelet function, with the clopidogrel-resistant patients receiving adjunctive cilostazol in addition to the aspirin and clopidogrel. From 2013 to 2015 (period 3), 65 patients underwent CAS in conjunction with cilostazol and clopidogrel treatment. In all patients, the incidence of new ipsilateral ischemic lesions observed by diffusion-weighted imaging on the day after CAS, and ischemic or hemorrhagic events occurring within 30 days were assessed. Results: Clopidogrel resistance was identified in 43% of the patients in period 1, in 16% in period 2, and in 5% in period 3 (P < 0.001). The on-treatment platelet reactivity results indicated that the PRU value during cilostazol-based DAPT was significantly lower than that observed for the standard DAPT (P < 0.05). New ipsilateral ischemic lesions decreased by 9% and 8% in periods 2 and 3, respectively, versus a 25% decrease in period 1 (P = 0.047). However, there were no significant differences noted for any of the hemorrhagic or thromboembolic events. Conclusions: Compared to the standard aspirin and clopidogrel dual antiplatelet therapy, cilostazol-based dual antiplatelet treatment reduces the rate of clopidogrel resistance and suppresses new ischemic lesions without hemorrhagic complications.

Nickel-associated delayed multiple white matter lesions after stent-assisted coil embolization of intracranial unruptured aneurysm

Metal-induced encephalopathy after stent-assisted coil embolization is extremely rare. The present report describes two patients who presented with symptomatic intracranial parenchymal edematous lesions after stent-assisted coil embolization. A 64-year-old woman underwent stent-assisted coil embolization for a left internal carotid artery aneurysm; 21 days after the procedure she presented with right hand weakness and MRI revealed multifocal white matter lesions. Another woman aged 52 years underwent stent-assisted coil embolization for right vertebral artery aneurysm; 18 days after the procedure she presented with left-sided sensory disturbance and MRI demonstrated multiple white matter lesions. Treatment in both cases resulted in improvement of these lesions after steroid pulse therapy, and the patients had no associated morbidity 4 months after the procedures. Clinicians should monitor for neurologic symptoms and postoperative delayed radiologic parenchymal edematous changes associated with the metal allergic reaction after nitinol stent-assisted coil embolization.

Pretreatment with and ongoing use of omega-3 fatty acid ethyl esters reduce the slow-flow phenomenon and prevent in-stent restenosis in patients undergoing carotid artery stenting

Objective: Carotid artery stenting (CAS) is a less invasive alternative to carotid endarterectomy, but it is essential to prevent thromboembolic complications during CAS and to suppress in‐stent restenosis (ISR) after CAS because of the relatively high risk of periprocedural and follow‐up stroke events. Clinical trials have demonstrated the strong relationship of carotid plaque vulnerability with the subsequent risk of ipsilateral ischemic stroke and thromboembolic complications during CAS. Recent studies demonstrated that both low eicosapentaenoic acid (EPA) and low docosahexaenoic acid (DHA) levels were significantly associated with lipid‐rich coronary and carotid plaques, but little is known about the effect of administration of omega‐3 fatty acids (O‐3FAs) containing EPA and DHA before and after CAS for stabilizing carotid plaque, preventing thromboembolic complications, and suppressing ISR. In this study, the efficacy of pretreatment with and ongoing daily use of O‐3FA in addition to statin treatment was evaluated in patients undergoing CAS. Methods: This study was a nonrandomized prospective trial with retrospective analysis of historical control data. From 2012 to 2015, there were 100 consecutive patients with hyperlipidemia undergoing CAS for carotid artery stenosis who were divided into two groups. Between 2012 and 2013 (control period), 47 patients were treated with standard statin therapy. Between 2014 and 2015 (O‐3FA period), patients were treated with statin therapy and add‐on oral O‐3FA ethyl esters containing 750 mg/d DHA and 1860 mg/d EPA from 4 weeks before CAS, followed by ongoing daily use for at least 12 months. In all patients, the plaque morphology by virtual histology intravascular ultrasound, the incidence of new ipsilateral ischemic lesions on the day after CAS, the slow‐flow phenomenon during CAS, and ISR within 12 months after CAS were compared between the periods. Results: The slow‐flow phenomenon during CAS with filter‐type embolic protection devices decreased in the O‐3FA period (1 of 53 patients [2%]) compared with the control period (7 of 47 patients [15%]; P = .02). Furthermore, ISR for 12 months after CAS was significantly decreased in the O‐3FA period (1 of 53 patients [2%]) compared with the control period (10 of 47 patients [21%]; P = .01). On virtual histology intravascular ultrasound analysis, the fibrofatty area was significantly smaller and the fibrous area was significantly greater in the O‐3FA period. On multivariate logistic regression analysis, a low EPA/arachidonic acid ratio and a symptomatic lesion were the factors related to vulnerable plaque (P = .01 [odds ratio, 5.24; 95% confidence interval, 1.65‐16.63] and P = .01 [odds ratio, 11.72; 95% confidence interval, 2.93‐46.86], respectively). Conclusions: Pretreatment with O‐3FA reduces the slow‐flow phenomenon generated by plaque vulnerability during CAS, and on‐going daily use of O‐3FA suppresses ISR after CAS.

Central retinal artery thromboembolism without ophthalmic artery occlusion during stent-assisted coil embolization of an ophthalmic artery aneurysm

BACKGROUND Recent reports have described that endovascular treatment of coil embolization of opththalmic artery (OphA) aneurysms has a relative risk of visual disruption caused by thromboembolic infarction of the central retinal artery (CRA), especially the OphA when it originates within the body of the aneurysm. Patent microthrombus in the OphA might also cause retinal infarction that affects visual acuity. We describe stent-assisted coil embolization of an OphA aneurysm complicated with a severe visual disturbance, although normal flow was scrupulously maintained in the OphA during the procedure. The visual disturbance was recovered by early treatment. CASE DESCRIPTION A 40-year-old woman who presented with an intracranial aneurysm arising from the right OphA underwent stent-assisted coil embolization under general anesthesia. Although the area around the origin of the OphA was intentionally avoided and anterograde flow in the OphA was monitored by repeated angiography during this procedure, sight in the right eye was lost immediately thereafter. The immediate application of ocular massage and intraarterial fibrinolysis improved vision in the right eye to essentially normal status after discharge. CONCLUSIONS Despite good anterograde flow in the OphA during aneurysm embolization, the procedural risk of a visual disturbance due to thromboembolic complications of CRA occlusion cannot be avoided. Anterograde flow in the OphA and retinochoroidal blush should be monitored by repeated angiography during coil embolization to prevent vision loss. Should vision be lost, a rapid response including ocular massage and intraarterial fibrinolysis is required for recovery.

Successful Coil Embolization of Pediatric Carotid Cavernous Fistula Due to Ruptured Posttraumatic Giant Internal Carotid Artery Aneurysm

BACKGROUND The goal of the treatment of direct carotid cavernous fistula (CCF) is to occlude the arteriovenous shunt and to preserve the patency of the concerned internal carotid artery. However, for the ipsilateral posttraumatic fragile cerebrum, coil embolization plus parent artery occlusion for the high-flow direct CCF is better for the prevention of hyperperfusion syndrome and intracranial hemorrhage. We experienced such a case and managed it successfully. CASE DESCRIPTION A 6-year-old boy had severe head trauma caused by being hit by a car. He was transferred to our department and diagnosed as having left acute subdural hematoma and acute brain swelling. Emergent evacuation of hematoma and external decompression were performed. He was treated for severe brain swelling in the intensive care unit for 2 months. Cranioplasty was performed 3 months after the injury. His right hemiparesis and aphasia persisted, so he was transferred to a rehabilitation hospital. However, 2 years after the head injury, he was referred to our department because of abducens nerve palsy. He was diagnosed as having a symptomatic posttraumatic direct CCF, which was caused by a ruptured left cavernous giant internal carotid artery aneurysm. The direct CCF was treated with coil embolization of the giant aneurysm and parent artery occlusion. CONCLUSIONS Coil embolization of the aneurysm and parent artery occlusion for the posttraumatic direct CCF was a good option to manage the abducens nerve palsy and to prevent postoperative hyperperfusion.