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Collateral growth after acute occlusion of an intracranial artery is triggered by increasing shear stress in preexisting collateral pathways. Recently, sphingosine-1-phosphate receptor-1 (S1PR1) on endothelial cells was reported to be essential in sensing fluid shear stress. Here, we evaluated the expression of S1PR1 in the hypoperfused mouse brain and investigated the effect of a selective S1PR1 agonist on leptomeningeal collateral growth and subsequent ischemic damage after focal ischemia.In C57Bl/6 mice (n = 133) subjected to unilateral common carotid occlusion (CCAO) and sham surgery. The first series examined the time course of collateral growth, cell proliferation, and S1PR1 expression in the leptomeningeal arteries after CCAO. The second series examined the relationship between pharmacological regulation of S1PR1 and collateral growth of leptomeningeal anastomoses. Animals were randomly assigned to one of the following groups: LtCCAO and daily intraperitoneal (i.p.) injection for 7 days of an S1PR1 selective agonist (SEW2871, 5 mg/kg/day); sham surgery and daily i.p. injection for 7 days of SEW2871 after surgery; LtCCAO and daily i.p. injection for 7 days of SEW2871 and an S1PR1 inverse agonist (VPC23019, 0.5 mg/kg); LtCCAO and daily i.p. injection of DMSO for 7 days after surgery; and sham surgery and daily i.p. injection of DMSO for 7 days. Leptomeningeal anastomoses were visualized 14 days after LtCCAO by latex perfusion method, and a set of animals underwent subsequent permanent middle cerebral artery occlusion (pMCAO) 7 days after the treatment termination. Neurological functions 1 hour, 1, 4, and 7 days and infarction volume 7 days after pMCAO were evaluated.In parallel with the increase in S1PR1 mRNA levels, S1PR1 expression colocalized with endothelial cell markers in the leptomeningeal arteries, increased markedly on the side of the CCAO, and peaked 7 days after CCAO. Mitotic cell numbers in the leptomeningeal arteries increased after CCAO. Administration of the S1PR1 selective agonist significantly increased cerebral blood flow (CBF) and the diameter of leptomeningeal collateral vessels (42.9 ± 2.6 μm) compared with the controls (27.6 ± 5.7 μm; P < 0.01). S1PR1 inverse agonist administration diminished the effect of the S1PR1 agonist (P < 0.001). After pMCAO, S1PR1 agonist pretreated animals showed significantly smaller infarct volume (17.5% ± 4.0% vs. 7.7% ± 4.0%, P < 0.01) and better functional recovery than vehicle-treated controls.These results suggest that S1PR1 is one of the principal regulators of leptomeningeal collateral recruitment at the site of increased shear stress and provide evidence that an S1PR1 selective agonist has a role in promoting collateral growth and preventing of ischemic damage and neurological dysfunction after subsequent stroke in patients with intracranial major artery stenosis or occlusion.

In-stent stenosis (ISS) triggered by a metal-induced allergic reaction of Pipeline embolization device (PED) placement is extremely rare. The present report describes a patient who presented with delayed parent artery occlusion and refractory ISS after PED placement due to cobalt allergy. A patient in her 70s underwent PED placement for a right internal carotid artery (ICA) large aneurysm; 4 months later, the patient presented with left-sided hemiparesis, and MRI revealed right ICA occlusion even though antiplatelet therapy was optimal. She underwent mechanical thrombectomy, and successful recanalization was achieved. However, follow-up angiography 6 months after the thrombectomy revealed severe ISS, and the patch testing showed a positive reaction for cobalt. As a result of long-term administration of oral steroids and antihistamine, progression of ISS was suppressed. It was supposed that a delayed hypersensitivity reaction to cobalt might induce refractory ISS after PED placement. [ABSTRACT FROM AUTHOR]

Graves' disease (GD) accounts for a large proportion of pediatric hyperthyroidism, and the first-line treatment is antithyroid drug (ATD) therapy. Methimazole (MMI) is effective in most patients but is associated with significant adverse events (AEs). We reviewed the medical records of GD patients (n = 56) with onset age of <15 yr and investigated the relationship between MMI dose and AEs. The study population comprised 11 male and 45 female patients and the median age at diagnosis was 11 yr. All patients were initially treated with ATDs. Among the 52 patients initially treated with MMI, 20 received a low dose, and 32 received a high dose of MMI (< 0.7 vs > 0.7 mg/kg/ day., respectively). AEs occurred in 20% of the patients in the low-dose MMI group, and in 50% patients in the high-dose MMI group (p = 0.031). A greater variety of AEs was observed in the high-dose group. Neutropenia and rash were observed in both groups. With treatment transition to low-dose MMI according to the Japanese Society for Pediatric Endocrinology guidelines, we expect a decrease in the incidence of AEs in future. However, we should be careful as neutropenia and rash can occur independently of the MMI dose. [ABSTRACT FROM AUTHOR]