bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single-Ring Posterior Left Atrial (Box) Isolation Results in a Different Mode of Recurrence Compared With Wide Antral Pulmonary Vein Isolation on Long-Term Follow-Up
Authors: Lim Toon Wei , Koay Choon Hiang , See Valerie A. , McCall Rebecca , Chik William , Zecchin Robert , Byth Karen , Seow Swee-Chong , Thomas Liza , Ross David L. , Thomas Stuart P. 
Published: September 2012

Background—
Electric isolation of the pulmonary veins and posterior left atrium with a single ring of radiofrequency lesions (single-ring isolation [SRI]) may result in fewer atrial fibrillation (AF) recurrences than wide antral pulmonary vein isolation (wide antral isolation [WAI]) by abolishing extravenous AF triggers. The effect of mitral isthmus line (MIL) ablation on outcomes after SRI has not previously been assessed.

Methods and Results—

We randomly assigned 220 consecutive patients (58±10 years old; 82% men) with highly symptomatic AF (61% paroxysmal, 39% persistent/longstanding persistent) to undergo either SRI or WAI. Half of each cohort was also randomly allocated to have left lateral MIL ablation (2×2 factorial study design). Patients were followed clinically and with 7-day Holter studies for arrhythmia recurrences. The primary end points were recurrence of AF and organized atrial tachyarrhythmias. AF-free survival at 2 years was better after SRI (74% [95% CI, 65%–82%]) than WAI (61% [51%–70%];
P
=0.031). Organized atrial tachyarrhythmia–free survival was similar after SRI and WAI (67% [57%–75%] ersus 64% [54%–72%], respectively, at 2 years;
P
=0.988). MIL ablation resulted in better 2-year organized atrial tachyarrhythmia–free survival (71% [62%–79%] versus 60% [50%–69%];
P
=0.07), which approached statistical significance. Survival free of any atrial arrhythmia after one procedure was not significantly affected by isolation technique or MIL ablation.

Conclusions—
SRI resulted in fewer AF recurrences compared with WAI on long-term follow-up but did not reduce the recurrence of all atrial arrhythmias. MIL ablation may reduce organized atrial tachyarrhythmia recurrences.

Clinical Trial Registration—

http://www.anzctr.org.au
; ACTRN12606000467538.
Age-Dependent Effect of β-Blockers in Preventing Vasovagal Syncope
Authors: Sheldon Robert S. , Morillo Carlos A. , Klingenheben Thomas , Krahn Andrew D. , Sheldon Aaron , Rose M. Sarah 
Published: September 2012

Background—
β-blockers have little effectiveness in preventing vasovagal syncope in unselected populations, but they might be effective in older patients. We determined whether β-blockers prevent vasovagal syncope in an age-related fashion.

Methods and Results—

Two populations were studied. A proportional hazards analysis was performed on an observational cohort study of 153 patients with vasovagal syncope, 52 of whom received β-blockers. A multivariable proportional hazards model stratified by center was performed on 208 participants in the randomized Prevention of Syncope Trial (POST), examining the interaction between age group and treatment with metoprolol. Age-specific hazard ratios were estimated for both studies and combined using the inverse variance meta-analytic method. In the cohort study, the hazard ratio for syncope if treated with β-blockers was 1.54 (95% CI, 0.78–3.05) for patients aged <42 years and 0.48 (95% CI, 0.12–1.92) for patients aged ≥42 years. In POST, the proportional hazards model showed interactions between age and treatment effect (
P
=0.026). The hazard ratio for patients aged ≥42 years who received metoprolol was 0.53 (95% CI, 0.25–1.10); in patients aged <42 years, the hazard ratio was 1.62 (95% CI, 0.85–3.10). A pooled analysis of both studies yielded an estimate of the hazard ratio of 1.58 (CI, 1.00–2.31) for patients aged <42 years, and the hazard ratio was 0.52 (CI, 0.27–1.01) for patients aged ≥42 years. The 2 age groups differed significantly in response to β-blockers (
P
=0.007).

Conclusions—
β-blocker treatment may suppress vasovagal syncope in middle-aged patients aged >42 years.
Association of Mild to Moderate Chronic Kidney Disease With Venous Thromboembolism
Authors: Mahmoodi Bakhtawar K. , Gansevoort Ron T. , Næss Inger Anne , Lutsey Pamela L. , Brækkan Sigrid K. , Veeger Nic J.G.M. , Brodin Ellen E. , Meijer Karina , Sang Yingying , Matsushita Kunihiro , Hallan Stein I. , Hammerstrøm Jens , Cannegieter Suzanne C. , Astor Brad C. , Coresh Josef , Folsom Aaron R. , Hansen John-Bjarne , Cushman Mary 
Published: September 2012

Background—
Recent findings suggest that chronic kidney disease (CKD) may be associated with an increased risk of venous thromboembolism (VTE). Given the high prevalence of mild-to-moderate CKD in the general population, in depth analysis of this association is warranted.

Methods and Results—

We pooled individual participant data from 5 community-based cohorts from Europe (second Nord-Trøndelag Health Study [HUNT2], Prevention of Renal and Vascular End-stage Disease [PREVEND], and the Tromsø study) and the United States (Atherosclerosis Risks in Communities [ARIC] and Cardiovascular Health Study [CHS]) to assess the association of estimated glomerular filtration rate (eGFR), albuminuria, and CKD with objectively verified VTE. To estimate adjusted hazard ratios for VTE, categorical and continuous spline models were fit by using Cox regression with shared-frailty or random-effect meta-analysis. A total of 1178 VTE events occurred over 599 453 person-years follow-up. Relative to eGFR 100 mL/min per 1.73 m
2
, hazard ratios for VTE were 1.29 (95% confidence interval, 1.04–1.59) for eGFR 75, 1.31 (1.00–1.71) for eGFR 60, 1.82 (1.27–2.60) for eGFR 45, and 1.95 (1.26–3.01) for eGFR 30 mL/min per 1.73 m
2
. In comparison with an albumin-to-creatinine ratio (ACR) of 5.0 mg/g, the hazard ratios for VTE were 1.34 (1.04–1.72) for ACR 30 mg/g, 1.60 (1.08–2.36) for ACR 300 mg/g, and 1.92 (1.19–3.09) for ACR 1000 mg/g. There was no interaction between clinical categories of eGFR and ACR (
P
=0.20). The adjusted hazard ratio for CKD, defined as eGFR <60 mL/min per 1.73 m
2
or albuminuria ≥30 mg/g, (versus no CKD) was 1.54 (95% confidence interval, 1.15–2.06). Associations were consistent in subgroups according to age, sex, and comorbidities, and for unprovoked versus provoked VTE, as well.

Conclusions—
Both eGFR and ACR are independently associated with increased risk of VTE in the general population, even across the normal eGFR and ACR ranges.
Higher Stroke Unit Volume Associated With Improved Quality of Early Stroke Care and Reduced Length of Stay
Authors: Svendsen Marie Louise , Ehlers Lars Holger , Ingeman Annette , Johnsen Søren Paaske 
Published: September 2012

Background and Purpose—
Specialized stroke unit care improves outcome among patients with stroke, but it is unclear whether there are any scale advantages in costs and clinical outcome from treating a larger number of patients. We examined whether the case volume in stroke units was associated with quality of early stroke care, mortality, and hospital bed-day use.

Methods—
In a nationwide population-based cohort study, we identified 63 995 patients admitted to stroke units in Denmark between 2003 and 2009. Data on exposure, outcome, and covariates were collected prospectively. Comparisons were clustered within stroke units and adjusted for patient and hospital characteristics.

Results—
Patients in high-volume stroke units overall had a better prognostic profile than patients in low-volume stroke units. Patients in high-volume stroke units also received more processes of care in the early phase of stroke compared with patients in low-volume stroke units (unadjusted difference, 9.84 percentage points; 95% CI, 3.98–15.70). High stroke unit volume was associated with shorter length of the initial hospital stay (adjusted ratio, 0.49; 95% CI, 0.41–0.59) and reduced bed-day use in the first year after stroke (adjusted ratio, 0.79; 95% CI, 0.70–0.87). No association between volume and mortality was found.

Conclusions—
Patients admitted to high-volume stroke units received a higher quality of early stroke care and spent fewer days in the hospital compared with patients in low-volume units. We observed no association between volume and mortality.
Detailed Analysis of Periprocedural Strokes in Patients Undergoing Intracranial Stenting in Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS)
Authors: Fiorella David , Derdeyn Colin P. , Lynn Michael J. , Barnwell Stanley L. , Hoh Brian L. , Levy Elad I. , Harrigan Mark R. , Klucznik Richard P. , McDougall Cameron G. , Pride G. Lee , Zaidat Osama O. , Lutsep Helmi L. , Waters Michael F. , Hourihane J. Maurice , Alexandrov Andrei V. , Chiu David , Clark Joni M. , Johnson Mark D. , Torbey Michel T. , Rumboldt Zoran , Cloft Harry J. , Turan Tanya N. , Lane Bethany F. , Janis L. Scott , Chimowitz Marc I. 
Published: September 2012

Background and Purpose—
Enrollment in the Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) trial was halted due to the high risk of stroke or death within 30 days of enrollment in the percutaneous transluminal angioplasty and stenting arm relative to the medical arm. This analysis focuses on the patient and procedural factors that may have been associated with periprocedural cerebrovascular events in the trial.

Methods—
Bivariate and multivariate analyses were performed to evaluate whether patient and procedural variables were associated with cerebral ischemic or hemorrhagic events occurring within 30 days of enrollment (termed periprocedural) in the percutaneous transluminal angioplasty and stenting arm.

Results—

Of 224 patients randomized to percutaneous transluminal angioplasty and stenting, 213 underwent angioplasty alone (n=5) or with stenting (n=208). Of these, 13 had hemorrhagic strokes (7 parenchymal, 6 subarachnoid), 19 had ischemic stroke, and 2 had cerebral infarcts with temporary signs within the periprocedural period. Ischemic events were categorized as perforator occlusions (13), embolic (4), mixed perforator and embolic (2), and delayed stent occlusion (2). Multivariate analyses showed that higher percent stenosis, lower modified Rankin score, and clopidogrel load associated with an activated clotting time above the target range were associated (
P
≤0.05) with hemorrhagic stroke. Nonsmoking, basilar artery stenosis, diabetes, and older age were associated (
P
≤0.05) with ischemic events.

Conclusions—
Periprocedural strokes in SAMMPRIS had multiple causes with the most common being perforator occlusion. Although risk factors for periprocedural strokes could be identified, excluding patients with these features from undergoing percutaneous transluminal angioplasty and stenting to lower the procedural risk would limit percutaneous transluminal angioplasty and stenting to a small subset of patients. Moreover, given the small number of events, the present data should be used for hypothesis generation rather than to guide patient selection in clinical practice.

Clinical Trial Registration Information—

URL:
http://clinicaltrials.gov
. Unique Identifier: NCT00576693.
Mutant Erythropoietin Without Erythropoietic Activity Is Neuroprotective Against Ischemic Brain Injury
Authors: Gan Yu , Xing Juan , Jing Zheng , Stetler R. Anne , Zhang Feng , Luo Yumin , Ji Xunming , Gao Yanqin , Cao Guodong 
Published: September 2012

Background and Purpose—
Erythropoietin (EPO) confers potent neuroprotection against ischemic injury. However, treatment for stroke requires high doses and multiple administrations of EPO, which may cause deleterious side effects due to its erythropoietic activity. This study identifies a novel nonerythropoietic mutant EPO and investigates its potential neuroprotective effects and underlying mechanism in an animal model of cerebral ischemia.

Methods—

We constructed a series of mutant EPOs, each containing a single amino acid mutation within the erythropoietic motif, and tested their erythropoietic activity. Using cortical neuronal cultures exposed to
N
-methyl
-d-
aspartate neurotoxicity and a murine model of transient middle cerebral artery occlusion, neuroprotection and neurofunctional outcomes were assessed as well as activation of intracellular signaling pathways.

Results—

The serine to isoleucine mutation at position 104 (S104I-EPO) completely abolished the erythropoietic and platelet-stimulating activity of EPO. Administration of S104I-EPO significantly inhibited
N
-methyl-
d
-aspartate-induced neuronal death in primary cultures and protected against cerebral infarction and neurological deficits with an efficacy similar to that of wild-type EPO. Both S104-I-EPO and wild-type EPO activated similar prosurvival signaling pathways such as phosphatidylinositol 3-kinase/AKT, mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2, and STAT5. Inhibition of phosphatidylinositol 3-kinase/AKT or mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 signaling pathways significantly attenuated the neuroprotective effects of S104-I-EPO, indicating that activation of these pathways underlies the neuroprotective mechanism of mutant EPO against cerebral ischemia.

Conclusions—
S104-I-EPO confers neuroprotective effects comparable to those of wild-type EPO against ischemic brain injury with the added benefit of lacking erythropoietic and platelet-stimulating side effects. Our novel findings suggest that the nonerythropoietic mutant EPO is a legitimate candidate for ischemic stroke intervention.
Evaluating Linkages of Weather Patterns and Water Quality Responses in South Florida Using a Synoptic Climatological Approach
Authors: Sheridan Scott C. , Pirhalla Douglas E. , Lee Cameron C. , Ransibrahmanakul Varis 
Published: September 2012

AbstractCoastal ocean ecosystems are impacted by atmospheric conditions and events, including episodic severe systems such as hurricanes as well as more regular seasonal events. The complexity of the atmosphere–ocean relationship makes establishing concrete connections difficult. In this paper, this relationship is assessed through synoptic climatological methods, a technique well established in applied climatological research but heretofore rarely used in assessing coastal ocean water quality and ecological status. Historical sea level pressure data are used to define 10 circulation patterns across the southeastern United States and adjacent Gulf of Mexico, based on the spatial pattern of sea level pressure, which can then be associated with the presence of cyclones, precipitation, and wind stress. The frequency of these patterns, and their deviation from climatological means, is then compared with Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) chlorophyll observations over the Florida Bay and south Florida shelf for the period 1997–2010. Several circulation patterns indicative of cyclonic activity over the broader region are associated with increased chlorophyll levels in the study area, while several other patterns, indicative of anticyclonic conditions, are associated with decreased chlorophyll levels. These relationships are spatially and temporally variable, generally with stronger correlations observed in winter and spring, and farther north in the study region when compared with more southern locations near the Florida Keys. The results here demonstrate the potential of using synoptic analysis and derived statistics for tracking and modeling changes in chlorophyll and other indicators related to water quality and biological health.
Large-Eddy Simulation of Roll Vortices in a Hurricane Boundary Layer
Authors: Nakanishi Mikio , Niino Hiroshi 
Published: September 2012

Abstract
For the last decade, horizontal roll vortices have been often observed in hurricane boundary layers (HBLs). In this study, a large-eddy simulation is performed to explore the formation mechanism of the horizontal roll vortices and their significance in a near-neutrally stratified HBL at 40 km (R40) and 100 km (R100) from the center of the hurricane. Results are examined through turbulence statistics and empirical orthogonal function (EOF) analysis. The EOF analysis and budgets of turbulent kinetic energy demonstrate that an inflection-point instability in the radial velocity profile is responsible for the roll vortices with horizontal wavelengths of 1.5–2.4 km in the HBL both for R40 and R100. The roll vortices for R40 are nearly aligned with the gradient wind, while those for R100 are oriented slightly to the left of that wind. Also the horizontal distributions of velocity fluctuations suggest the presence of streaklike structures at horizontal intervals of several hundred meters near the ground surface. Internal gravity waves, Kelvin–Helmholtz waves, and entrainments occur above the HBL and are partly coupled with the roll vortices in the HBL, implying an enhancement of vertical transports of momentum and other quantities between the HBL and the free atmosphere.
Zonal-Mean Dynamics of Extended Recoveries from Stratospheric Sudden Warmings
Authors: Hitchcock Peter , Shepherd Theodore G. 
Published: September 2012

AbstractThe recovery of the Arctic polar vortex following stratospheric sudden warmings is found to take upward of 3 months in a particular subset of cases, termed here polar-night jet oscillation (PJO) events. The anomalous zonal-mean circulation above the pole during this recovery is characterized by a persistently warm lower stratosphere, and above this a cold midstratosphere and anomalously high stratopause, which descends as the event unfolds. Composites of these events in the Canadian Middle Atmosphere Model show the persistence of the lower-stratospheric anomaly is a result of strongly suppressed wave driving and weak radiative cooling at these heights. The upper-stratospheric and lower-mesospheric anomalies are driven immediately following the warming by anomalous planetary-scale eddies, following which, anomalous parameterized nonorographic and orographic gravity waves play an important role. These details are found to be robust for PJO events (as opposed to sudden warmings in general) in that many details of individual PJO events match the composite mean.A zonal-mean quasigeostrophic model on the sphere is shown to reproduce the response to the thermal and mechanical forcings produced during a PJO event. The former is well approximated by Newtonian cooling. The response can thus be considered as a transient approach to the steady-state, downward control limit. In this context, the time scale of the lower-stratospheric anomaly is determined by the transient, radiative response to the extended absence of wave driving. The extent to which the dynamics of the wave-driven descent of the stratopause can be considered analogous to the descending phases of the quasi-biennial oscillation (QBO) is also discussed.
The Troposphere-to-Stratosphere Transition in Kinetic Energy Spectra and Nonlinear Spectral Fluxes as Seen in ECMWF Analyses
Authors: Burgess B. H. , Erler Andre R. , Shepherd Theodore G. 
Published: September 2012

AbstractGlobal horizontal wavenumber kinetic energy spectra and spectral fluxes of rotational kinetic energy and enstrophy are computed for a range of vertical levels using a T799 ECMWF operational analysis. Above 250 hPa, the kinetic energy spectra exhibit a distinct break between steep and shallow spectral ranges, reminiscent of dual power-law spectra seen in aircraft data and high-resolution general circulation models. The break separates a large-scale “balanced” regime in which rotational flow strongly dominates divergent flow and a mesoscale “unbalanced” regime where divergent energy is comparable to or larger than rotational energy. Between 230 and 100 hPa, the spectral break shifts to larger scales (from n = 60 to n = 20, where n is spherical harmonic index) as the balanced component of the flow preferentially decays. The location of the break remains fairly stable throughout the stratosphere. The spectral break in the analysis occurs at somewhat larger scales than the break seen in aircraft data. Nonlinear spectral fluxes defined for the rotational component of the flow maximize between about 300 and 200 hPa. Large-scale turbulence thus centers on the extratropical tropopause region, within which there are two distinct mechanisms of upscale energy transfer: eddy–eddy interactions sourcing the transient energy peak in synoptic scales, and zonal mean–eddy interactions forcing the zonal flow. A well-defined downscale enstrophy flux is clearly evident at these altitudes. In the stratosphere, the transient energy peak moves to planetary scales and zonal mean–eddy interactions become dominant.
Climatology of Non-Gaussian Atmospheric Statistics
Authors: Perron Maxime , Sura Philip 
Published: September 2012

Abstract
A common assumption in the earth sciences is the Gaussianity of data over time. However, several independent studies in the past few decades have shown this assumption to be mostly false. To be able to study non-Gaussian climate statistics, one must first compile a systematic climatology of the higher statistical moments (skewness and kurtosis; the third and fourth central statistical moments, respectively). Sixty-two years of daily data from the NCEP–NCAR Reanalysis I project are analyzed. The skewness and kurtosis of the data are found at each spatial grid point for the entire time domain. Nine atmospheric variables were chosen for their physical and dynamical relevance in the climate system: geopotential height, relative vorticity, quasigeostrophic potential vorticity, zonal wind, meridional wind, horizontal wind speed, vertical velocity in pressure coordinates, air temperature, and specific humidity. For each variable, plots of significant global skewness and kurtosis are shown for December–February and June–August at a specified pressure level. Additionally, the statistical moments are then zonally averaged to show the vertical dependence of the non-Gaussian statistics. This is a more comprehensive look at non-Gaussian atmospheric statistics than has been taken in previous studies on this topic.
The Relationship of Rainfall Variability in Western Equatorial Africa to the Tropical Oceans and Atmospheric Circulation. Part I: The Boreal Spring
Authors: Nicholson Sharon E. , Dezfuli Amin K. 
Published: September 2012

Abstract
This paper examines the factors governing rainfall variability in western equatorial Africa (WEA) during the April–June rainy season. In three of the five regions examined some degree of large-scale forcing is indicated, particularly in the region along the Atlantic coast. Interannual variability in this coastal sector also demonstrates a strong link to changes in local sea surface temperatures (SSTs) and the South Atlantic subtropical high.
To examine potential causal mechanisms, various atmospheric parameters are evaluated for wet and dry composites. The results suggest that the intensity of the zonal circulation in the global tropics is a crucial control on rainfall variability over WEA. A La Niña (El Niño)–like signal in both SSTs and zonal circulation over the Pacific is apparent in association with the wet (dry) conditions in the western sector. However, remote forcing from the Pacific modulates the circulation over Africa indirectly by way of synchronous changes in the entire Indian or Atlantic Ocean.
Anomalies in the local zonal winds are similar in all three regions: the wet (dry) composite is associated with an intensification (weakening) of the upper-tropospheric easterlies and low-level westerlies, but a weakening (intensification) of the midlevel easterlies. This work also suggests that, in most cases, the relationship between local SSTs and rainfall reflects a common remote forcing by the large-scale atmosphere–ocean system. This forcing is manifested via changes in the zonal circulation. Thus, the statistical associations between rainfall and SSTs do not indicate direct forcing by local SSTs. One point of evidence for this conclusion is the stronger association with atmospheric parameters than with SSTs.