Description: Background and Purpose— Predictors of progression of intracranial atherosclerotic stenosis have not been clearly identified. We investigated whether poststroke changes in lipid profiles would affect the prognosis of symptomatic intracranial atherosclerotic stenosis. Methods— This is a substudy of Trial of cilOstazol in Symptomatic intracranial Stenosis 2 (TOSS-2). From 10 centers we enrolled 230 subjects with acute symptomatic stenosis in the M1 segment of the middle cerebral artery or basilar artery. At baseline and 7 months after stroke, subjects underwent MR angiogram and assessment of cardiovascular risk factors including lipoprotein levels. Progression of intracranial atherosclerotic stenosis was determined by comparing stenosis on the baseline and follow-up MR angiograms. Results— Cilostazol treatment was more frequently seen in the nonprogression group (109 of 198 [55.1%]) than in the progression group (11 of 32 [34.4%]). At 7 months after stroke when compared with baseline, low-density lipoprotein cholesterol and total cholesterol levels decreased in both groups. However, only nonprogressors showed increase in high-density lipoprotein cholesterol levels between baseline and follow-up. Changes in apolipoprotein B/apolipoprotein A-I levels were not different between the groups, although apolipoprotein B/A-I at 7 months was higher in progressors than in nonprogressors. Remnant lipoprotein cholesterol levels decreased in nonprogressors, whereas they did not change in progressors. In multivariable analyses, after adjusting for cilostazol treatment and remnant lipoprotein cholesterol reduction or apolipoprotein B/A-I at 7 months, high-density lipoprotein cholesterol elevation remained as a significant predictor for the nonprogression. Conclusions— This is the first prospective multicenter study to demonstrate that high-density lipoprotein cholesterol elevation, along with remnant lipoprotein cholesterol reduction and low apolipoprotein B/A-I, is associated with prevention of angiographic progression of symptomatic intracranial atherosclerotic stenosis. Clinical Trial Registration Information— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00130039.

Description: Rationale: The peptide ligand apelin and its receptor APJ constitute a signaling pathway with numerous effects on the cardiovascular system, including cardiovascular development in model organisms such as xenopus and zebrafish. Objective: This study aimed to characterize the embryonic lethal phenotype of the Apj –/– mice and to define the involved downstream signaling targets. Methods and Results: We report the first characterization of the embryonic lethality of the Apj –/– mice. More than half of the expected Apj –/– embryos died in utero because of cardiovascular developmental defects. Those succumbing to early embryonic death had markedly deformed vasculature of the yolk sac and the embryo, as well as poorly looped hearts with aberrantly formed right ventricles and defective atrioventricular cushion formation. Apj –/– embryos surviving to later stages demonstrated incomplete vascular maturation because of a deficiency of vascular smooth muscle cells and impaired myocardial trabeculation and ventricular wall development. The molecular mechanism implicates a novel, noncanonical signaling pathway downstream of apelin-APJ involving Gα13, which induces histone deacetylase (HDAC) 4 and HDAC5 phosphorylation and cytoplasmic translocation, resulting in activation of myocyte enhancer factor 2. Apj –/– mice have greater endocardial Hdac4 and Hdac5 nuclear localization and reduced expression of the myocyte enhancer factor 2 (MEF2) transcriptional target Krüppel-like factor 2 . We identify a number of commonly shared transcriptional targets among apelin-APJ, Gα13, and MEF2 in endothelial cells, which are significantly decreased in the Apj –/– embryos and endothelial cells. Conclusions: Our results demonstrate a novel role for apelin-APJ signaling as a potent regulator of endothelial MEF2 function in the developing cardiovascular system.

Description: Objective— The influence of high-dose statin therapy on the serial stent healing process has not been fully investigated. Using optical coherence tomography, the effect of high-dose statin therapy on stent strut coverage was evaluated in drug-eluting stent–treated patients. Approach and Results— Sixty patients were randomly assigned to 2 groups according to the statin dose (atorvastatin 40 mg as high-dose statin therapy [n=29] versus pravastatin 20 mg as low-dose statin therapy [n=31]). Serial optical coherence tomographic evaluation post procedure and at the 3-month and 12-month follow-ups was performed in 50 patients with 54 stents (23 atorvastatin-treated patients versus 27 pravastatin-treated patients). The percentage of uncovered struts was defined as the ratio of uncovered struts/total struts. The primary end point was the percentage of uncovered struts at the 12-month follow-up. The secondary end point was the percentage of uncovered struts at the 3-month follow-up and the comparative percentage change () of uncovered struts at the 3- and 12-month follow-ups between the different dose statin therapies. The percentage of uncovered struts was 7.4% (range, 4.3%–10.4%) in atorvastatin-treated patients versus 10.6% (range, 5.7%–22.6%) in pravastatin-treated patients at the 3-month follow-up ( P =0.13) and 1.3% (0.3%–3.8%) versus 2.5% (0.9%–9.7%), respectively, at the 12-month follow-up ( P =0.01). The percentage of uncovered struts from 3 to 12 months of follow-up was –7.9±8.5% in atorvastatin-treated patients versus –9.3±12.5% in pravastatin-treated patients ( P =0.67). Conclusions— This study suggested that high-dose statin therapy might provide a beneficial effect for the vascular healing process after drug-eluting stent implantation.

Description: Background and Purpose— Most patients with cerebral infarction die of brain edema because of the breakdown of the blood–brain barrier (BBB) in ischemic tissue. Caveolins (a group of proteins) are key modulators of vascular permeability; however, a direct role of caveolin-1 (Cav-1) in the regulation of BBB permeability during ischemic injury has yet to be identified. Methods— Cav-1 expression was measured by immunoblotting after photothrombotic ischemia. A direct functional role of Cav-1 in cerebral edema and BBB permeability during cerebral ischemia was investigated by genetic manipulation (gene disruption and re-expression) of Cav-1 protein expression in mice. Results— There was a significant correlation between the extent of BBB disruption and the Cav-1 expression. In Cav-1–deficient (Cav-1 –/– ) mice, the extent of BBB disruption after cerebral ischemia was increased compared with wild-type (Cav-1 +/+ ) mice, whereas the increase in cerebral edema volume was ameliorated by lentiviral-mediated re-expression of Cav-1. Furthermore, Cav-1 –/– mice had significantly higher degradation of tight junction proteins and proteolytic activity of matrix metalloproteinase than Cav-1 +/+ mice. Conversely, re-expression of Cav-1 in Cav-1 –/– mice restored tight junction protein expression and reduced matrix metalloproteinase proteolytic activity. Conclusions— These results indicate that Cav-1 is a critical determinant of BBB permeability. Strategies for regulating Cav-1 represent a novel therapeutic approach to controlling BBB disruption and subsequent neurological deterioration during cerebral ischemia.

Description: Background and Purpose— We investigated clinical and radiological characteristics of ischemic stroke patients with Takotsubo-like myocardial dysfunction. Methods— From multicenter stroke registry database, ischemic stroke patients who underwent transthoracic echocardiography were found. Among these, patients were classified if they had specific ventricular regional wall motion abnormalities discording with coronary artery distribution, such as apical (typical pattern) or nonapical ballooning (atypical pattern), considered as echocardiographic findings of Takotsubo cardiomyopathy. Patients with ischemic heart disease history, myocarditis, or pheochromocytoma were excluded. We compared patients with Takotsubo-like myocardial dysfunction with those without and further performed systematic literature review on those with Takotsubo cardiomyopathy. Results— This study included 23 patients (0.42%). The mean age was 70.7±13.9 years, with predominance of women (73.9%) and typical pattern of Takotsubo-like myocardial dysfunction (91.3%). They were associated with short-term poor functional outcomes, including high mortality, neurological deterioration, and functional status at discharge, compared with those without (39.1% versus 2.4%, 47.8% versus 7.4%; and median [interquartile range], 5 [5–6] versus 3 [2–4]; all P 〈0.001). They had a higher inflammatory marker level and lower triglyceride level. Ischemic lesions were more commonly found in the right anterior circulation with specific dominant regions being the insula and peri-insular areas. In addition, a trend toward a remarkable mortality rate and higher prevalence of insular involvement was observed in the propensity-score matching, subgroup fulfilling the strict Takotsubo cardiomyopath criteria, and was as reported in literature review. Conclusion— Stroke patients with Takotsubo-like myocardial dysfunction may differ from those without in clinical outcomes, laboratory findings, and radiological features.

Description: Background and Purpose— The aim of this study was to investigate differences in risk factors and stroke mechanisms between intracranial atherosclerosis (ICAS) and extracranial atherosclerosis (ECAS) and between anterior and posterior circulation atherosclerosis. Methods— A multicenter, prospective, Web-based registry was performed on atherosclerotic strokes using diffusionweighted magnetic resonance imaging and magnetic resonance angiography. Stroke mechanisms were categorized as artery-to-artery embolism, in situ thrombo-occlusion, local branch occlusion, or hemodynamic impairment. Results— Onethousand patients were enrolled from 9 university hospitals. Age (odds ratio [OR], 1.033; 95% confidence interval [CI], 1.018–1.049), male gender (OR, 3.399; 95% CI, 2.335–4.949), and hyperlipidemia (OR, 1.502; 95% CI, 1.117–2.018) were factors favoring ECAS (vs ICAS), whereas hypertension (OR, 1.826; 95% CI, 1.274–2.618; P =0.001) and diabetes mellitus (OR, 1.490; 95% CI, 1.105–2.010; P =0.009) were related to posterior (vs anterior) circulation diseases. Metabolic syndrome was a factor related to ICAS (vs ECAS) only in posterior circulation strokes (OR, 2.433; 95% CI, 1.005–5.890; P =0.007). Stroke mechanisms included arterytoartery embolism (59.7%), local branch occlusion (14.9%), in situ thrombo-occlusion (13.7%), hemodynamic impairment (0.9%), and mixed (10.8%). Anterior ICAS was more often associated with artery-to-artery embolism (51.8% vs 34.0%) and less often associated with local branch occlusion (12.3% vs 40.4%) than posterior ICAS ( P 〈0.001). Conclusions— The prevalence of risk factors and stroke mechanisms differ between ICAS and ECAS, and between anterior and posterior circulation atherosclerosis. Posterior ICAS seems to be closely associated with metabolic derangement and local branch occlusion. Prevention and management strategies may have to consider these differences.

Description: Background and Purpose— To elucidate the mechanisms and prognosis of rotational vertebral artery occlusion (RVAO). Methods— We analyzed clinical and radiological characteristics, patterns of induced nystagmus, and outcome in 21 patients (13 men, aged 29–77 years) with RVAO documented by dynamic cerebral angiography during an 8-year period at 3 University Hospitals in Korea. The follow-up periods ranged from 5 to 91 months (median, 37.5 months). Most patients (n=19; 90.5%) received conservative treatments. Results— All the patients developed vertigo accompanied by tinnitus (38%), fainting (24%), or blurred vision (19%). Only 12 (57.1%) patients showed the typical pattern of RVAO during dynamic cerebral angiography, a compression of the dominant vertebral artery at the C1-2 level during contralateral head rotation. The induced nystagmus was mostly downbeat with horizontal and torsional components beating toward the compressed vertebral artery side. None of the patients with conservative treatments developed posterior circulation stroke, and 4 of them (21.1%) showed resolution of symptoms during the follow-ups. Conclusions— RVAO has various patterns of vertebral artery compression, and favorable long-term outcome with conservative treatments. In most patients with RVAO, the symptoms may be ascribed to asymmetrical excitation of the bilateral labyrinth induced by transient ischemia or by disinhibition from inferior cerebellar hypoperfusion. Conservative management might be considered as the first-line treatment of RVAO.

Description: Objective— Although stem cell factor (SCF) has been shown to play a critical role in hematopoiesis, gametogenesis, and melanogenesis, the function of SCF in the regulation of vascular integrity has not been studied. Approach and Results— We demonstrated that SCF binds to and activates the cKit receptor in endothelial cells, thereby increasing the internalization of vascular endothelial-cadherin and enhancing extravasation of dyes to a similar extent as vascular endothelial growth factor. SCF-mediated cKit activation in endothelial cells enhanced the phosphorylation of endothelial nitric oxide (NO) synthase via the phosphoinositide 3-kinase/Akt signaling pathway and subsequently increased the production of NO. Inhibition of endothelial NO synthase expression and NO synthesis using small interfering RNA knockdown and chemical inhibitors substantially diminished the ability of SCF to increase the internalization of vascular endothelial-cadherin and in vitro endothelial permeability. SCF-induced increase in extravasation of the dyes was abrogated in endothelial NO synthase knockout mice, which indicates that endothelial NO synthase–mediated NO production was responsible for the SCF-induced vascular leakage. Furthermore, we demonstrated that the expression of SCF and cKit was significantly higher in the retina of streptozotocin-injected diabetic mice than in the nondiabetic control animals. Depletion of SCF by intravitreous injection of anti-SCF–neutralizing immunoglobulin G significantly prevented vascular hyperpermeability in the retinas of streptozotocin-injected diabetic mice. Conclusions— Our data reveal that SCF disrupts the endothelial adherens junction and enhances vascular leakage, as well as suggest that anti-SCF/cKit therapy may hold promise as a potential therapy for the treatment of hyperpermeable vascular diseases.

Description: Objective— Apelin and its cognate receptor Aplnr/Apj are essential for diverse biological processes. However, the function of Apelin signaling in lymphatic development remains to be identified, despite the preferential expression of Apelin and Aplnr within developing blood and lymphatic endothelial cells in vertebrates. In this report, we aim to delineate the functions of Apelin signaling during lymphatic development. Approach and Results— We investigated the functions of Apelin signaling during lymphatic development using zebrafish embryos and found that attenuation of Apelin signaling substantially decreased the formation of the parachordal vessel and the number of lymphatic endothelial cells within the developing thoracic duct, indicating an essential role of Apelin signaling during the early phase of lymphatic development. Mechanistically, we found that abrogation of Apelin signaling selectively attenuates lymphatic endothelial serine–threonine kinase Akt 1/2 phosphorylation without affecting the phosphorylation status of extracellular signal–regulated kinase 1/2. Moreover, lymphatic abnormalities caused by the reduction of Apelin signaling were significantly exacerbated by the concomitant partial inhibition of serine–threonine kinase Akt/protein kinase B signaling. Apelin and vascular endothelial growth factor-C (VEGF-C) signaling provide a nonredundant activation of serine–threonine kinase Akt/protein kinase B during lymphatic development because overexpression of VEGF-C or apelin was unable to rescue the lymphatic defects caused by the lack of Apelin or VEGF-C, respectively. Conclusions— Taken together, our data present compelling evidence suggesting that Apelin signaling regulates lymphatic development by promoting serine–threonine kinase Akt/protein kinase B activity in a VEGF-C/VEGF receptor 3–independent manner during zebrafish embryogenesis.