Stroke awareness decreases prehospital delay after acute ischemic stroke in korea

BACKGROUND: Delayed arrival at hospital is one of the major obstacles in enhancing the rate of thrombolysis therapy in patients with acute ischemic stroke. Our study aimed to investigate factors associated with prehospital delay after acute ischemic stroke in Korea. METHODS: A prospective, multicenter study was conducted at 14 tertiary hospitals in Korea from March 2009 to July 2009. We interviewed 500 consecutive patients with acute ischemic stroke who arrived within 48 hours. Univariate and multivariate analyses were performed to evaluate factors influencing prehospital delay. RESULTS: Among the 500 patients (median 67 years, 62% men), the median time interval from symptom onset to arrival was 474 minutes (interquartile range, 170-1313). Early arrival within 3 hours of symptom onset was significantly associated with the following factors: high National Institutes of Health Stroke Scale (NIHSS) score, previous stroke, atrial fibrillation, use of ambulance, knowledge about thrombolysis and awareness of the patient/bystander that the initial symptom was a stroke. Multivariable logistic regression analysis indicated that awareness of the patient/bystander that the initial symptom was a stroke (OR 4.438, 95% CI 2.669-7.381), knowledge about thrombolysis (OR 2.002, 95% CI 1.104-3.633) and use of ambulance (OR 1.961, 95% CI 1.176-3.270) were significantly associated with early arrival. CONCLUSIONS: In Korea, stroke awareness not only on the part of patients, but also of bystanders, had a great impact on early arrival at hospital. To increase the rate of thrombolysis therapy and the incidence of favorable outcomes, extensive general public education including how to recognize stroke symptoms would be important.ope

Clinical associations and prognostic value of MRI-visible perivascular spaces in patients with ischemic stroke or TIA: a pooled analysis

BACKGROUND AND OBJECTIVES: Visible perivascular spaces are an MRI marker of cerebral small vessel disease and might predict future stroke. However, results from existing studies vary. We aimed to clarify this through a large collaborative multicenter analysis. METHODS: We pooled individual patient data from a consortium of prospective cohort studies. Participants had recent ischemic stroke or transient ischemic attack (TIA), underwent baseline MRI, and were followed up for ischemic stroke and symptomatic intracranial hemorrhage (ICH). Perivascular spaces in the basal ganglia (BGPVS) and perivascular spaces in the centrum semiovale (CSOPVS) were rated locally using a validated visual scale. We investigated clinical and radiologic associations cross-sectionally using multinomial logistic regression and prospective associations with ischemic stroke and ICH using Cox regression. RESULTS: We included 7,778 participants (mean age 70.6 years; 42.7% female) from 16 studies, followed up for a median of 1.44 years. Eighty ICH and 424 ischemic strokes occurred. BGPVS were associated with increasing age, hypertension, previous ischemic stroke, previous ICH, lacunes, cerebral microbleeds, and white matter hyperintensities. CSOPVS showed consistently weaker associations. Prospectively, after adjusting for potential confounders including cerebral microbleeds, increasing BGPVS burden was independently associated with future ischemic stroke (versus 0-10 BGPVS, 11-20 BGPVS: HR 1.19, 95% CI 0.93-1.53; 21+ BGPVS: HR 1.50, 95% CI 1.10-2.06; = 0.040). Higher BGPVS burden was associated with increased ICH risk in univariable analysis, but not in adjusted analyses. CSOPVS were not significantly associated with either outcome. DISCUSSION: In patients with ischemic stroke or TIA, increasing BGPVS burden is associated with more severe cerebral small vessel disease and higher ischemic stroke risk. Neither BGPVS nor CSOPVS were independently associated with future ICH

Impact of Cerebral Microbleeds in Stroke Patients with Atrial Fibrillation

OBJECTIVES: Cerebral microbleeds are associated with the risks of ischemic stroke and intracranial hemorrhage, causing clinical dilemmas for antithrombotic treatment decisions. We aimed to evaluate the risks of intracranial hemorrhage and ischemic stroke associated with microbleeds in patients with atrial fibrillation treated with Vitamin K antagonists, direct oral anticoagulants, antiplatelets, and combination therapy (i.e. concurrent oral anticoagulant and antiplatelet) METHODS: We included patients with documented atrial fibrillation from the pooled individual patient data analysis by the Microbleeds International Collaborative Network. Risks of subsequent intracranial hemorrhage and ischemic stroke were compared between patients with and without microbleeds, stratified by antithrombotic use. RESULTS: A total of 7,839 patients were included. The presence of microbleeds was associated with an increased relative risk of intracranial hemorrhage (aHR 2.74, 95% confidence interval 1.76 - 4.26) and ischemic stroke (aHR 1.29, 95% confidence interval 1.04 - 1.59). For the entire cohort, the absolute incidence of ischemic stroke was higher than intracranial hemorrhage regardless of microbleeds burden. However, for the subgroup of patients taking combination of anticoagulant and antiplatelet therapy, the absolute risk of intracranial hemorrhage exceeded that of ischemic stroke in those with 2-4 microbleeds (25 vs 12 per 1,000 patient-years) and ≥11 microbleeds (94 vs 48 per 1,000 patient-years). INTERPRETATION: Patients with atrial fibrillation and high burden of microbleeds receiving combination therapy have a tendency of higher rate of intracranial hemorrhage than ischemic stroke, with potential for net harm. Further studies are needed to help optimize stroke preventive strategies in this high-risk group. This article is protected by copyright. All rights reserved

Effects of Ce and P addition on as-cast structure and formation mechanism of cerium compounds in Ce-added TWIP steels

In TWIP steels, the addition of Ce and P results in the finer as-cast structure which arises from the pinning effect of the Ce-rich compounds against the coalescence of the neighboring columnar grains. Cerium compounds consists of three groups: a multilayered core-shell structure composed of (Ce,Ca)(S,Se), Ce(S,Se,As,P) and CeP, a structure consisting of Ce(As,P) and CeP, and the CeP compound independently formed in the matrix. The Ce(S,Se,As,P), Ce(As,P) and CeP compounds have the same crystal structure as that of they gamma matrix which is Fm (3) over barm, while the (Ce,Ca)(S,Se) compound holds a R (3) over barm CeKS2 crystal structure. The orientation of all the cerium phosphides in the core-shell structures are perfectly identical. The formation sequence of the multilayered core-shell structure depends on the binding forces between Ce and X(S,Se,As,P). (C) 2016 Elsevier Inc. All rights reserved.110Nsciescopu

Determination of Yield Stress in a Duplex Steel with plus Lamellar Structure

Yield stress sigma(y) is evaluated in a duplex steel with + lamellar structure by calculating the stress for the propagation of pile-up dislocations in one phase into another phase. Effective grain size of a lamella is determined to calculate the contribution of each boundary of a lamella to dislocation pile-up. Comparison of stresses required to drive -to- and -to- propagations of pile-up dislocations suggests that + lamellar structure yields by propagation of pile-up dislocations in lamella to lamella. sigma(y) of + lamellar structure is calculated as the sum of friction stress sigma(o) of and the stress component sigma for yielding of lamella at the effective grain size d(,eff) of lamella. The calculated results explain better to the experimental sigma(y) than do results calculated using rule of mixture.11Nsciescopu

Roles of Molybdenum and Tungsten on Reheat Cracking Susceptibility of 2.25Cr Heat Resistant Steels

The rupture time of the tungsten-alloyed steel is much shorter than that of the molybdenum-alloyed steel. The fracture mode of the former steel is typically intergranular, but the latter steel shows a mixed fracture mode of intergranular and ductile. The shorter rupture time of the tungsten-alloyed steel is due to the active carbide formation reaction of tungsten in ferrite which depletes carbon within the matrix; the resulting higher segregation concentration of phosphorus at GCls and carbide-free PAGBs. The longer rupture time of the other steel arises from two factors: the molybdenum segregated at the interfaces as a grain boundary strengthener; the repulsive segregation between carbon and phosphorus which repels phosphorus from the interfaces and produces the lower segregation concentration of phosphorus.110Ysciescopu

Roles of bulk carbon content on grain size, carbide reactions and intergranular rupture life in 2.25cr martensitic heat resistant steels

The steel of a higher bulk carbon content shows the denser precipitation distribution of carbides after the solution treatment followed by tempering. Such a carbide distribution produces the smaller prior austenite grain size after the welding simulation at a high temperature. Because the equilibrium segregation concentration of phosphorus decreases with decreasing prior austenite grain size, the specimen of the higher bulk carbon content shows therefore the longer intergranular rupture life. The rupture life is also increased by the partitioning of phosphorus pre-segregated at prior austenite grain boundary/carbide interfaces onto the fresh surface of precipitates formed on the surface of pre-formed carbides. The intergranular rupture life is additionally increased by the repulsive segregation between carbon and phosphorus which decreases the overall phosphorus segregation concentration at the prior austenite grain boundaries.1142sciescopuskc

Deformation Behavior in Medium Mn Steel of Nanometer-Sized α′ + γ Lamellar Structure

Yielding and work-hardening phenomena in an Fe-10.62Mn-2.84Al-0.17C-0.5Mo steel, which is composed of nanometer-sized lamellae of alpha' and gamma, are described on the basis of the Hall-Petch relations. Unlike the general expectation, yielding in the steel, which consists of lamellae of alpha' and mechanically stable gamma, occurs through the propagation of pileup dislocations from alpha' to gamma. However, when gamma is mechanically unstable, yielding occurs through the stress-assisted martensitic transformation (SAMT) within the unstable gamma region, resulting in a low YS of about 500 MPa. The overall prominent work-hardening behavior of this steel after yielding is due to the active SAMT, which does not accompany the increase in mobile dislocation density and so causes the high elastic strain rate. The carbon partitioning treatment increases the SAMT starting strength to about 980 MPa, which is caused by the mechanical stabilization of gamma. The overall low work-hardening behavior of this case is mainly attributed to the active propagation of pile-up dislocation from alpha' to gamma which causes the high plastic strain rate through the abrupt increase of mobile dislocation density.1110sciescopu

Precipitation correlation between MC carbide and Nb-rich M2P phosphide in a TP347H austenitic stainless steel

The precipitation correlation between Nb-rich MC carbides and Nb-rich M2P phosphides has been investigated in a TP347H austenitic stainless steel during rupture test at 750 degrees C. Needle-like Nb-rich M2P phosphides as well as round-shaped Nb-rich MC is observed during rupture test. The Nb-rich M2P phosphides form an orthorhombic NbNiP-type structure and show the orientation relationship of [0 (1) over bar0]M2P//[100]gamma and (20 (1) over bar )M2P//(0 (11) over bar)gamma. The fraction of the Nb-rich MC carbides decreases abruptly after a critical rupture time, while that of M2P phosphides is roughly little changed. This means that the dissolution of the pre-formed Nb-rich MC carbides into the matrix for meeting the equilibrium phase fraction of each phase activates the active precipitation and growth of the Nb-rich M2P phosphides. Such a precipitation correlation may delay intergranular cracking occurring in the austenitic stainless steel. (C) 2016 Elsevier Inc All rights reserved.1131sciescopu