bluuebunny/crossref_metadata_2025 huggingface dataset:
Proteasomal Inhibition Promotes ATP-Binding Cassette Transporter A1 (ABCA1) and ABCG1 Expression and Cholesterol Efflux From Macrophages In Vitro and In Vivo
Authors: Ogura Masatsune , Ayaori Makoto , Terao Yoshio , Hisada Tetsuya , Iizuka Maki , Takiguchi Shunichi , Uto-Kondo Harumi , Yakushiji Emi , Nakaya Kazuhiro , Sasaki Makoto , Komatsu Tomohiro , Ozasa Hideki , Ohsuzu Fumitaka , Ikewaki Katsunori
Published: August 2011

Objective—

ATP-binding cassette transporter A1 (ABCA1) and ABCG1 are key molecules in an initial step of reverse cholesterol transport (RCT), a major antiatherogenic property of high-density lipoprotein (HDL). The ubiquitin-proteasome system (UPS) mediates nonlysosomal pathways for protein degradation and is known to be involved in atherosclerosis. However, little is known about the effects of the UPS on these molecules and overall RCT. We therefore investigated whether UPS inhibition affects ABCA1/G1 expression in macrophages and RCT in vitro and in vivo.

Methods and Results—

Various proteasome inhibitors increased ABCA1/G1 expression in macrophages, translating into enhanced apolipoprotein A-I– and HDL-mediated cholesterol efflux from macrophages. ABCA1 and ABCG1 were found to undergo polyubiquitination in the macrophages and HEK293 cells overexpressing these proteins, and pulse-chase analysis revealed that proteasome inhibitors inhibited ABCA1/G1 protein degradation. In in vivo experiments, the proteasome inhibitor bortezomib increased ABCA1/G1 protein levels in mouse peritoneal macrophages, and RCT assays showed that it significantly increased the fecal (54% increase compared with saline) and plasma (23%) appearances of the tracer derived from intraperitoneally injected
3
H-cholesterol-labeled macrophages.

Conclusion—

The present study provided evidence that the UPS is involved in ABCA1/G1 degradation, thereby affecting RCT in vivo. Therefore, specific inhibition of the UPS pathway might lead to a novel HDL therapy that enhances RCT.
Interactions Between Smoking, Pulmonary Surfactant Protein B, and Atherosclerosis in the General Population
Authors: Nguyen Ann B. , Rohatgi Anand , Garcia Christine K. , Ayers Colby R. , Das Sandeep R. , Lakoski Susan G. , Berry Jarett D. , Khera Amit , McGuire Darren K. , de Lemos James A.
Published: August 2011

Objective—

Pulmonary surfactant protein B (SP-B), an alveolar protein normally detectable at only very low concentrations in blood, circulates at higher levels among smokers and those with alveolar injury and inflammation. We hypothesized that SP-B may serve as a marker of the vascular effects of smoking and would thus be associated with subclinical measures of atherosclerosis.

Methods and Results—

Plasma levels of SP-B were measured in 3294 subjects, ages 30 to 65, enrolled in the Dallas Heart Study, a probability-based population sample of Dallas County adults. Coronary artery calcium (CAC) was measured by computed tomography and abdominal aortic plaque (AP) by magnetic resonance imaging. The cohort comprised 29% current and 17% former smokers. The overall prevalence of CAC was 22%, and that of AP was 39%. Median SP-B levels were 5-fold higher among current versus never smokers (
P
<0.0001) and were significantly correlated with estimated pack-years smoked (Spearman ρ=0.35,
P
<0.0001). Increasing levels of SP-B also associated with other traditional cardiac risk factors and higher levels of inflammatory biomarkers. In univariable analyses, increasing SP-B quartiles associated with higher prevalence of both CAC and AP (
P
trend
<0.0001 for each). In multivariable analyses adjusting for traditional cardiovascular risk factors, SP-B remained associated with AP (OR 1.87 for the 4th versus 1st quartiles, 95% confidence interval 1.39 to 2.51;
P
<0.0001) but not CAC. An interaction was observed between SP-B, smoking status, and AP (
P
interaction
=0.01), such that SP-B associated with AP in current smokers (adjusted OR 2.15 for the 4th versus 1st quartile, 95% confidence interval 1.26 to 3.67;
P
=0.005) but not in former or never smokers.

Conclusion—

Circulating levels of SP-B increase with greater smoking burden and independently associate with abdominal AP among current smokers. Our findings support further investigation of the role of SP-B as a marker of the vascular effects of smoking.
Oxidized Low-Density Lipoprotein Activates p66
Shc
via Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1, Protein Kinase C-β, and c-Jun N-Terminal Kinase Kinase in Human Endothelial Cells
Authors: Shi Yi , Cosentino Francesco , Camici Giovanni G. , Akhmedov Alexander , Vanhoutte Paul M. , Tanner Felix C. , Lüscher Thomas F.
Published: August 2011

Objective—

Deletion of the mitochondrial gene p66
Shc
protects from endothelial dysfunction and atherosclerotic plaque formation in mice fed a high-fat diet. However, the molecular mechanisms underlying this beneficial effect have not yet been delineated. The present study was designed to elucidate the proatherogenic mechanisms by which p66
Shc
mediates oxidized low-density lipoprotein (oxLDL) uptake by the endothelium, a critical step in plaque formation.

Methods and Results—

Incubation of human aortic endothelial cells with oxLDL led to phosphorylation of p66
Shc
at Ser36. Inhibition of lectin-like oxLDL receptor-1 prevented p66
Shc
phosphorylation, confirming that this effect is mediated by lectin-like oxLDL receptor-1. OxLDL also increased phosphorylation of protein kinase C β
2
(PKCβ
2
) at both Thr641 and Ser660, as well as c-Jun N-terminal kinase (JNK). Furthermore, inhibition of PKCβ
2
prevented the activation of JNK, suggesting that PKCβ2 is upstream of JNK. Finally, p66
Shc
silencing blunted oxLDL-induced O
2
−.
production, underscoring the critical role of p66
Shc
in oxLDL-induced oxidative stress in endothelial cells.

Conclusion—

In this study we provide the molecular mechanisms mediating the previously observed atherogenic properties of p66
Shc
. Taken together, our data set the stage for the design of novel therapeutic tools to retard atherogenesis through the inhibition of p66
Shc
.
Orally Administered Eicosapentaenoic Acid Induces Rapid Regression of Atherosclerosis Via Modulating the Phenotype of Dendritic Cells in LDL Receptor-Deficient Mice
Authors: Nakajima Kenji , Yamashita Tomoya , Kita Tomoyuki , Takeda Masafumi , Sasaki Naoto , Kasahara Kazuyuki , Shinohara Masakazu , Rikitake Yoshiyuki , Ishida Tatsuro , Yokoyama Mitsuhiro , Hirata Ken-ichi
Published: August 2011

Objective—

Eicosapentaenoic acid (EPA) has been shown to have beneficial effects on cardiovascular diseases, although the precise mechanism is unknown. We investigated the effect of EPA on the regression of atherosclerosis.

Methods and Results—

LDL-receptor–deficient mice were fed a high-cholesterol diet for 8 weeks to build up aortic sinus atherosclerotic lesions and then were fed a normal diet with or without 5% EPA for 4 weeks. Atherosclerotic lesions were histologically assessed, and immunologic assays were performed. EPA treatment significantly regressed atherosclerosis (−22.7%,
P
<0.05) and decreased the content of macrophages, CD4
+
T cells, and dendritic cells (DCs) in atherosclerotic lesions, though only changing the chow never induced the regression. Flow cytometric analysis revealed that EPA increased immature DCs (CD11c
+
CD80
−
CD86
−
), increased the indoleamine 2,3-dioxygenase (IDO) in DCs, and decreased the number of CD4
+
T cells. In the presence of the IDO inhibitor, the beneficial effects of EPA on regression were inhibited, suggesting that the effect of EPA was mainly mediated through IDO.

Conclusion—

In addition to lowering plasma cholesterol, EPA regressed atherosclerosis probably due to modulation of DC phenotype and reduction in T cell numbers. The present findings might partly explain the beneficial effects of EPA in clinics and support clinical evidence.
Interleukin-10 Released by CD4
+
CD25
+
Natural Regulatory T Cells Improves Microvascular Endothelial Function Through Inhibition of NADPH Oxidase Activity in Hypertensive Mice
Authors: Kassan Modar , Galan Maria , Partyka Megan , Trebak Mohamed , Matrougui Khalid
Published: August 2011

Objective—

We previously demonstrated that a reduced number of CD

4
+

CD

25
+

-regulatory T cells (Tregs) was associated with microvascular dysfunction in hypertension. However, the underlying mechanism by which Tregs regulate vascular endothelial function remains unknown.

Methods and Results—

Control and interleukin (IL)-10
−/−
knockout mice were infused with angiotensin II (400 ng/kg/min) for 2 weeks (hypertensive [HT] and HT-IL-10
−/−
). Endothelium-dependent relaxation (EDR) in response to acetylcholine was significantly reduced in mesenteric resistance artery (MRA) from HT and HT-IL-10
−/−
compared with control and IL-10
−/−
mice. Importantly, the incubation of MRA from HT mice with the conditioned media of cultured Tregs, isolated from control mice, reduced NADPH oxidase activity and improved EDR, whereas no effect was observed in MRA from control mice incubated with the same media. These effects were reversed when MRAs were preincubated with IL-10 antibody or IL-10 receptor antagonist, whereas incubation with transforming growth factor-β receptor antagonist had no effect. The transfer of cultured Tregs, isolated from control mice, into HT-IL-10
−/−
mice reduced systolic blood pressure (SBP) and NADPH oxidase activity and improved EDR in MRA compared with untreated HT-IL-10
−/−
mice. In vivo treatment of HT mice with IL-10 (1000 ng/mouse) significantly reduced SBP and NADPH oxidase activity and improved EDR in MRA compared with untreated HT mice. The transfer of cultured Tregs, isolated from IL-10
−/−
mice, into HT mice did not reduce SBP or NADPH oxidase activity or improve EDR. The incubation of MRA from HT mice with apocynin improved EDR, whereas NADPH oxidase substrate attenuated EDR in MRA from control mice, which was reversed with exogenous IL-10.

Conclusion—

These data demonstrate that IL-10 released from Tregs attenuates NADPH oxidase activity, which is a critical process in the improvement of microvascular endothelial function in hypertension, suggesting that Tregs/IL-10 could be a therapeutic target for treatment of vasculopathy in hypertension.
Inhibitor of Apoptosis Proteins as Novel Targets in Inflammatory Processes
Authors: Mayer Bettina A. , Rehberg Markus , Erhardt Annette , Wolf Alexander , Reichel Christoph A. , Kracht Michael , Krombach Fritz , Tiegs Gisa , Zahler Stefan , Vollmar Angelika M. , Fürst Robert
Published: August 2011

Objective—

Inhibitor of apoptosis proteins (IAPs), such as X-linked or cellular IAP 1/2 (XIAP, cIAP1/2), are important regulators of apoptosis. IAP antagonists are currently under clinical investigation as anticancer agents. Interestingly, IAPs participate in the inflammation-associated TNF receptor signaling complex and regulate NFκB signaling. This raises the question about the role of IAPs in inflammation. Here, we investigated the anti-inflammatory potential of IAP inhibitors and the role of IAPs in inflammatory processes of endothelial cells.

Methods and Results—

In mice, the small molecule IAP antagonist A-4.10099.1 (ABT) suppressed antigen-induced arthritis, leukocyte infiltration in concanavalin A-evoked liver injury, and leukocyte transmigration in the TNFα-activated cremaster muscle. In vitro, we observed an attenuation of leukocyte–endothelial cell interaction by downregulation of the intercellular adhesion molecule-1. ABT did not impair NFκB signaling but decreased the TNFα-induced activation of the TGF-β–activated kinase 1, p38, and c-Jun N-terminal kinase. These effects are based on the proteasomal degradation of cIAP1/2 accompanied by an altered ratio of the levels of membrane-localized TNF receptor-associated factors 2 and 5.

Conclusion—

Our results reveal IAP antagonism as a profound anti-inflammatory principle in vivo and highlight IAPs as important regulators of inflammatory processes in endothelial cells.
A Unique MicroRNA Signature Associated With Plaque Instability in Humans
Authors: Cipollone Francesco , Felicioni Lara , Sarzani Riccardo , Ucchino Sante , Spigonardo Francesco , Mandolini Claudia , Malatesta Sara , Bucci Marco , Mammarella Chiara , Santovito Donato , de Lutiis Federica , Marchetti Antonio , Mezzetti Andrea , Buttitta Fiamma
Published: August 2011

Background and Purpose—

Atherosclerotic plaque rupture is considered the most important mechanism that underlies the onset of stroke, myocardial infarction, and sudden death. Several evidences demonstrated the pivotal role of inflammatory processes in plaque destabilization. MicroRNAs (miRNAs) are small endogenous RNAs and represent a new important class of gene regulators. Nevertheless, no data exist about the expression profile of miRNAs in atherosclerotic plaques. Thus, the aim of this study was to investigate the expression level of miRNAs in human plaques and to correlate it with clinical features of plaque destabilization.

Methods—

Two separate groups of plaques were collected from patients who underwent carotid endarterectomy in Chieti (n=15) and Ancona (n=38) Hospitals. All the plaques were subdivided in symptomatic (n=22) and asymptomatic (n=31) according to the presence/absence of stroke.

Results—

First, on the plaques collected at Chieti Hospital, we performed large-scale analysis of miRNA expression. Between the 41 miRNAs examined, we discovered profound differences in the expression of 5 miRNAs (miRNA-100, miRNA-127, miRNA-145, miRNA-133a, and miRNA-133b) in symptomatic versus asymptomatic plaques. Remarkably, when we repeated the analysis on the Ancona plaque subset, all these 5 miRNAs confirmed to be significantly more expressed in the symptomatic plaques. Finally, in vitro experiments on endothelial cells transfected with miRNA-145 and miRNA-133a confirmed the importance of these miRNAs in the modulation of stroke-related proteins.

Conclusions—

These results are the first to report alterations in the expression of specific miRNAs in human atherosclerotic plaques and suggest that miRNAs may have an important role in regulating the evolution of atherosclerotic plaque toward instability and rupture. Furthermore, by identifying the specific miRNA signature for stroke now, we are able to use computer algorithms to identify previously unrecognized molecular targets.
Socioeconomic Differences in Quality of Care and Clinical Outcome After Stroke
Authors: Langagergaard Vivian , Palnum Kaare H. , Mehnert Frank , Ingeman Annette , Krogh Birgitte R. , Bartels Paul , Johnsen Søren P.
Published: August 2011

Background and Purpose—

The association among socioeconomic status, quality of care, and clinical outcome after stroke remains poorly understood. In a Danish nationwide follow-up study, we examined whether socioeconomic-related differences in acute stroke care occur and, if so, whether they explain socioeconomic differences in case-fatality and readmission risk.

Methods—

Using population-based public registries, we identified and followed all patients aged ≤65 years admitted with stroke from 2003 to 2007 (n=14 545). We compared the proportion of patients receiving 7 specific processes of care according to income, educational attainment, and employment status. Furthermore, we computed 30-day and 1-year hazard ratios for death and readmission adjusted for patient characteristics and received processes of acute stroke care.

Results—

For low-income patients and disability pensioners, the relative risk of receiving all of the relevant processes of care was 0.82 (95% CI, 0.78 to 0.86) and 0.83 (95% CI, 0.79 to 0.87), respectively, compared with high-income patients and employed patients. Adjusted 30-day and 1-year hazard ratios for death for unemployed patients were 1.57 (95% CI, 1.25 to 1.97) and 1.58 (1.32 to 1.88), respectively, compared with employed patients. Unemployed patients also had a higher risk of readmission. The differences in mortality and readmission risk remained after controlling for received processes of acute stroke care.

Conclusions—

Low socioeconomic status was associated with a lower chance of receiving optimal acute stroke care. However, the differences in acute care did not appear to explain socioeconomic differences in mortality and readmission risk.
Intraventricular Fibrinolysis Versus External Ventricular Drainage Alone in Intraventricular Hemorrhage
Authors: Gaberel Thomas , Magheru Cristian , Parienti Jean-Jacques , Huttner Hagen Bernhard , Vivien Denis , Emery Evelyne
Published: August 2011

Background and Purpose—

The purpose of this study was to analyze the effect of intraventricular fibrinolysis (IVF) compared with external ventricular drainage alone on mortality and functional outcome in the management of intraventricular hemorrhage secondary to spontaneous supratentorial intracerebral hemorrhage.

Methods—

The authors conducted a systematic review and performed a meta-analysis. They reviewed the PubMed, Cochrane Library, and Liliacs databases. In addition, they conducted a manual review of article bibliographies.

Results—

Using a prespecified search strategy, 4 randomized and 8 observational studies were included in a meta-analysis. These studies involved a total of 316 patients with intraventricular hemorrhage at baseline, of whom 167 had IVF (52·8%). Pooled odds ratios of the impact of IVF on patient mortality, functional outcomes, and complications were calculated. The overall mortality risk decreased from 46·7% in the external ventricular drainage alone group to 22.7% in the external ventricular drainage+IVF group, corresponding to an overall pooled Peto OR of 0.32 (95% CI, 0.19 to 0.52). This result was highly significant with urokinase, not with recombinant tissue-type plasminogen activator. IVF was also associated with an increase in good functional outcome. There was no difference between the 2 groups in terms of shunt dependence and complications.

Conclusions—

The combination of IVF and external ventricular drainage in the management of severe intraventricular hemorrhage secondary to small intracerebral hemorrhage in young patients was associated with better survival and functional outcome results. Urokinase and recombinant tissue-type plasminogen activator could not have the same therapeutic effects. Well-designed randomized trials with special considerations to the fibrinolytic agents are needed.
Predictors of Early and Late Case-Fatality in a Nationwide Danish Study of 26 818 Patients With First-Ever Ischemic Stroke
Authors: Andersen Klaus Kaae , Andersen Zorana Jovanovic , Olsen Tom Skyhøj
Published: August 2011

Background and Purpose—

Predictors of early case-fatality (3-day, 7-day, and 30-day) in first-ever ischemic stroke were identified and compared with predictors of late case-fatality (90-day and 1-year).

Methods—

A registry designed to register hospitalized patients with stroke in Denmark 2000 to 2007 holds 26 818 patients with first-ever ischemic stroke with information on stroke severity (Scandinavian Stroke Scale), CT scan, cardiovascular risk factors, marital status, and fatality within 1 year. Multiple logistic regression was used in identifying predictors.

Results—

Mean age was 71.2 years; 48.5% were women; mean Scandinavian Stroke Scale score was 43.9. Early case-fatality showed stroke severity and age were significant predictors of 3-day, 7-day, and 30-day case-fatality (nonlinear effect). In addition, atrial fibrillation (OR, 1.56) predicted 30-day case-fatality. For late case-fatality, significant predictors of 90-day and 1-year case-fatality were age, stroke severity (nonlinear effect), atrial fibrillation (OR, 1.37 and 1.57), and diabetes (OR, 1.35 and 1.33), respectively. Male gender (OR, 1.28), previous myocardial infarction (OR, 1.40), and smoking (OR, 1.21) were also associated with 1-year case-fatality. Alcohol consumption, hypertension, intermittent arterial claudication, and marital state had no influence. All case-fatality rates accelerated with increasing age, but 3-day and 7-day case-fatality rates tended to level off or decline at the highest ages.

Conclusions—

Age and stroke severity were the only significant predictors of fatality within the first poststroke week; they were associated with late case-fatality as well. Cardiovascular risk factors were associated with late case-fatality; with the exception of atrial fibrillation, they were not significantly associated with early case-fatality rates.
Preclinical Evidence Toward the Use of Ketamine for Recombinant Tissue-Type Plasminogen Activator-Mediated Thrombolysis Under Anesthesia or Sedation
Authors: Gakuba Clement , Gauberti Maxime , Mazighi Mikael , Defer Gilles , Hanouz Jean-Luc , Vivien Denis
Published: August 2011

Background and Purpose—

Endovascular treatment of ischemic stroke usually involves recombinant tissue-type plasminogen activator (rtPA)-mediated thrombolysis in anesthetized patients. Paradoxically, differential influences of anesthetic agents on thrombolysis outcome remain unknown.

Methods—

In situ thrombotic stroke was induced in mice by local injection of thrombin. Four hours after the ischemic onset, mice underwent rtPA-mediated thrombolysis either awake or subjected to different anesthetic regimens (propofol, isoflurane/N
2
O, ketamine). Infarct volume and arterial recanalization were assessed by MRI at 24 hours.

Results—

Whatever the anesthetic regimen, infarct volumes measured at 24 hours were not affected. However, in contrast with other anesthetic agents tested, ketamine dramatically reduced infarct volume when combined with rtPA.

Conclusions—

Altogether these data suggest that ketamine significantly improves the benefit of rtPA-induced thrombolysis after stroke.
Self-Reported Atrial Fibrillation and Risk of Stroke in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study
Authors: Soliman Elsayed Z. , Howard George , Meschia James F. , Cushman Mary , Muntner Paul , Pullicino Patrick M. , McClure Leslie A. , Judd Suzanne , Howard Virginia J.
Published: August 2011

Background and Purpose—

We compared the associations of self-reported atrial fibrillation (AF) and ECG-detected AF with incident stroke in the Risk of Stroke in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study.

Methods—

In this analysis, 27 109 participants aged 45 years or older without previous stroke were included. Stroke cases were identified and adjudicated during an average of 4.4 years of follow-up. Cox proportional hazards analysis was used to calculate hazard ratios (HR) of self-reported AF, ECG-detected AF, and AF detected by either method with incident stroke. We also examined the predictive ability of the Framingham Stroke Risk Score (FSRS) when the component AF was defined by different methods.

Results—

After adjustment for components of the FSRS, self-reported AF, ECG-detected AF, and AF by either method were predictive of incident stroke (HR, 1.41; 95% CI, 1.05–1.88; HR, 1.90; 95% CI, 1.10–3.27; HR, 1.53; 95% CI, 1.16–2.01, respectively). When self-report, ECG, or either method, separately, were considered as the method of AF ascertainment in the FSRS, the HR per 1% increase in the FSRS were identical across AF ascertainment methods (HR, 1.04; 95% CI, 1.03–1.04; HR, 1.04; 95% CI, 1.04–1.05; HR, 1.04; 95% CI, 1.03–1.04; respectively).

Conclusions—

Self-reported AF is a strong predictor of stroke that can be used interchangeably or in combination with ECG-detected AF in stroke risk prediction models.
Progression of Magnetic Resonance Imaging-Defined Brain Vascular Disease Predicts Vascular Events in Elderly
Authors: Longstreth W.T. , Arnold Alice M. , Kuller Lewis H. , Bernick Charles , Lefkowitz David S. , Beauchamp Norman J. , Manolio Teri A.
Published: August 2011

Background and Purpose—

To determine whether progression of MRI-defined vascular disease predicts subsequent vascular events in the elderly.

Methods—

The Cardiovascular Health Study, a longitudinal cohort study of vascular disease in the elderly, allows us to address this question because its participants had 2 MRI scans ≈5 years apart and have been followed for ≈9 years since the follow-up scan for incident vascular events.

Results—

Both MRI-defined incident infarcts and worsened white matter grade were significantly associated with heart failure, stroke, and death, but not transient ischemic attacks, angina, or myocardial infarction. Strongest associations occurred when both incident infarcts and worsened white matter grade were present for heart failure (hazard ratio, 1.79; 95% confidence interval, 1.18–2.73), stroke (hazard ratio, 2.58; 95% confidence interval, 1.53–4.36), death (hazard ratio, 1.69; 95% confidence interval, 1.28–2.24), and cardiovascular death (hazard ratio, 1.97; 95% confidence interval, 1.24–3.14).

Conclusions—

Progression of MRI-defined vascular disease identifies elderly people at increased risk for subsequent heart failure, stroke, and death. Whether aggressive risk factor management would reduce risk is unknown.
Estimating Atmospheric Boundary Layer Depth Using COSMIC Radio Occultation Data
Authors: Guo P. , Kuo Y.-H. , Sokolovskiy S. V. , Lenschow D. H.
Published: August 2011

This study presents an algorithm for estimating atmospheric boundary layer (ABL) depth from Global Positioning System (GPS) radio occultation (RO) data. The algorithm is applied to the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) RO data and validated using high-resolution radiosonde data from the island of St. Helena (16.0°S, 5.7°W), tropical (30°S–30°N) radiosondes collocated with RO, and European Centre for Medium-Range Weather Forecasts (ECMWF) high-resolution global analyses. Spatial and temporal variations of the ABL depth obtained from COSMIC RO data for a 1-yr period over tropical and subtropical oceans are analyzed. The results demonstrate the capability of RO data to resolve geographical and seasonal variations of ABL height. The spatial patterns of the variations are consistent with those derived from ECMWF global analysis. However, the ABL heights derived from ECMWF global analysis, on average, are negatively biased against those estimated from COSMIC GPS RO data. These results indicate that GPS RO data can provide useful information on ABL height, which is an important parameter for weather and climate studies.
The Basic Ingredients of the North Atlantic Storm Track. Part II: Sea Surface Temperatures
Authors: Brayshaw David James , Hoskins Brian , Blackburn Michael
Published: August 2011

The impact of North Atlantic SST patterns on the storm track is investigated using a hierarchy of GCM simulations using idealized (aquaplanet) and “semirealistic” boundary conditions in the atmospheric component (HadAM3) of the third climate configuration of the Met Office Unified Model (HadCM3). This framework enables the mechanisms determining the tropospheric response to North Atlantic SST patterns to be examined, both in isolation and in combination with continental-scale landmasses and orography.

In isolation, a “Gulf Stream” SST pattern acts to strengthen the downstream storm track while a “North Atlantic Drift” SST pattern weakens it. These changes are consistent with changes in the extratropical SST gradient and near-surface baroclinicity, and each storm-track response is associated with a consistent change in the tropospheric jet structure. Locally enhanced near-surface horizontal wind convergence is found over the warm side of strengthened SST gradients associated with ascending air and increased precipitation, consistent with previous studies.

When the combined SST pattern is introduced into the semirealistic framework (including the “North American” continent and the “Rocky Mountains”), the results suggest that the topographically generated southwest–northeast tilt in the North Atlantic storm track is enhanced. In particular, the Gulf Stream shifts the storm track south in the western Atlantic whereas the strong high-latitude SST gradient in the northeastern Atlantic enhances the storm track there.
Kinematics of the Secondary Eyewall Observed in Hurricane Rita (2005)
Authors: Didlake Anthony C. , Houze Robert A.
Published: August 2011

Airborne Doppler radar data collected from the concentric eyewalls of Hurricane Rita (2005) provide detailed three-dimensional kinematic observations of the secondary eyewall feature. The secondary eyewall radar echo shows a ring of heavy precipitation containing embedded convective cells, which have no consistent orientation or radial location. The axisymmetric mean structure has a tangential wind maximum within the reflectivity maximum at 2-km altitude and an elevated distribution of its strongest winds on the radially outer edge. The corresponding vertical vorticity field contains a low-level maximum on the inside edge, which is part of a tube of increased vorticity that rises through the center of the reflectivity tower and into the midlevels. The secondary circulation consists of boundary layer inflow that radially overshoots the secondary eyewall. A portion of this inflowing air experiences convergence and supergradient forces that cause the air to rise and flow radially outward back into the center of the reflectivity tower. This mean updraft stretches and tilts the vorticity field to increase vorticity on the radially inner side of the tangential wind maximum. Radially outside this region, perturbation motions decrease the vorticity at a comparable rate. Thus, both mean and perturbation motions actively strengthen the wind maximum of the secondary eyewall. These features combine to give the secondary eyewall a structure different from the primary eyewall as it builds to become the new replacement eyewall.
Multiple Changepoint Detection via Genetic Algorithms
Authors: Li Shanghong , Lund Robert
Published: August 2011

This paper studies genetic algorithms as a means of estimating the number of changepoints and their locations in a climatic time series. Such methods bypass classic subsegmentation algorithms, which sometimes yield suboptimal conclusions. Minimum description length techniques are introduced. These techniques require optimizing an objective function over all possible changepoint numbers and location times. The general objective functions allow for correlated data, reference station aspects, and/or nonnormal marginal distributions, all common features of climate time series. As an exhaustive evaluation of all changepoint configurations is not possible, the optimization is accomplished via a genetic algorithm that randomly walks through a subset of good models in an intelligent manner. The methods are applied in the analysis of 173 yr of annual precipitation measurements from New Bedford, Massachusetts, and the North Atlantic basin tropical cyclone record.
Influence of Twenty-First-Century Atmospheric and Sea Surface Temperature Forcing on West African Climate
Authors: Skinner Christopher B. , Ashfaq Moetasim , Diffenbaugh Noah S.
Published: August 2011

The persistence of extended drought events throughout West Africa during the twentieth century has motivated a substantial effort to understand the mechanisms driving African climate variability as well as the possible response to elevated greenhouse gas (GHG) forcing. An ensemble of global climate model experiments is used to examine the relative roles of future direct atmospheric radiative forcing and SST forcing in shaping potential future changes in boreal summer precipitation over West Africa. The authors find that projected increases in precipitation throughout the western Sahel result primarily from direct atmospheric radiative forcing. The changes in atmospheric forcing generate a slight northward displacement and weakening of the African easterly jet (AEJ), a strengthening of westward monsoon flow onto West Africa, and an intensification of the tropical easterly jet (TEJ). Alternatively, the projected decreases in precipitation over much of the Guinea Coast region are caused by SST changes induced by the atmospheric radiative forcing. The changes in SSTs generate a weakening of the monsoon westerlies and the TEJ as well as a decrease in low-level convergence and resultant rising air throughout the midlevels of the troposphere. Experiments suggest a potential shift in the regional moisture balance of West Africa should global radiative forcing continue to increase, highlighting the importance of climate system feedbacks in shaping the response of regional-scale climate to global-scale changes in radiative forcing.
A Bayesian ANOVA Scheme for Calculating Climate Anomalies, with Applications to the Instrumental Temperature Record
Authors: Tingley Martin P.
Published: August 2011

Climate datasets with both spatial and temporal components are often studied after removing from each time series a temporal mean calculated over a common reference interval, which is generally shorter than the overall length of the dataset. The use of a short reference interval affects the temporal properties of the variability across the records, by reducing the standard deviation within the reference interval and inflating it elsewhere. For an annually averaged version of the Climate Research Unit’s (CRU) temperature anomaly product, the mean standard deviation is 0.67°C within the 1961–90 reference interval, and 0.81°C elsewhere.

The calculation of anomalies can be interpreted in terms of a two-factor analysis of variance model. Within a Bayesian inference framework, any missing values are viewed as additional parameters, and the reference interval is specified as the full length of the dataset. This Bayesian scheme is used to re-express the CRU dataset as anomalies with respect to means calculated over the entire 1850–2009 interval spanned by the dataset. The mean standard deviation is increased to 0.69°C within the original 1961–90 reference interval, and reduced to 0.76°C elsewhere. The choice of reference interval thus has a predictable and demonstrable effect on the second spatial moment time series of the CRU dataset. The spatial mean time series is in this case largely unaffected: the amplitude of spatial mean temperature change is reduced by 0.1°C when using the 1850–2009 reference interval, while the 90% uncertainty interval of (−0.03, 0.23) indicates that the reduction is not statistically significant.
Application of Thin-Plate Splines in Two Dimensions to Oceanographic Tracer Data
Authors: Trossman David S. , Thompson LuAnne , Hautala Susan L.
Published: August 2011

This study explores the utility of the thin-plate spline (TPS) as a mapping procedure for oceanographic sections of bottle data in comparison with objective mapping (OM), sometimes referred to as objective interpolation. Standard OM techniques in oceanography require a priori assumptions about the structure of the errors associated with mapping when interpolating irregularly spaced data. Alternatively, the TPS can be used to approximate mapping errors by fitting a nonparametric model using multiple covariates with a less rigid, physically consistent, spatial correlation structure. The case is made that these errors reflect the sparsity of the data coverage and quantify mapping error better than the estimates using OM. It is demonstrated that the maps from the TPS recreate the essential large-scale features of chlorofluorocarbon- or freon-11 (CFC-11) concentrations and inferred “ages,” but smooth over smaller-scale features, such as eddies. The TPS can outperform OM when either the distance between the samples is larger than the correlation length scale or the signal-to-noise ratio is small. With more data, OM and TPS estimates yield increasingly similar results, but differ most markedly where there are extrema in the mapped fields, particularly at the domain boundaries. The TPS is recommended over OM when the spatial domain is sparsely sampled but the full range of covariates is known to be spanned by these samples.
Impacts of Mountain–Plains Solenoid on Diurnal Variations of Rainfalls along the Mei-Yu Front over the East China Plains
Authors: Sun Jianhua , Zhang Fuqing
Published: August 2011

Convection-permitting numerical experiments using the Weather Research and Forecasting (WRF) model are performed to examine the impact of a thermally driven mountain–plains solenoid (MPS) on the diurnal variations of precipitation and mesoscale convective vortices along the mei-yu front over the east China plains during 1–10 July 2007. The focus of the analyses is a 10-day simulation that used the 10-day average of the global analysis at 0000 UTC as the initial condition and the 10-day averages every 6 h as lateral boundary conditions (with diurnal variations only). Despite differences in the rainfall intensity and location, this idealized experiment successfully simulated the observed diurnal variation and eastward propagation of rainfall and mesoscale convective vortices along the mei-yu front. It was found that the upward branch of the MPS, along with the attendant nocturnal low-level jet, is primarily responsible for the midnight-to-early-morning rainfall enhancement along the mei-yu front. The MPS is induced by differential heating between the high mountain ranges in central China and the low-lying plains in east China. Diabatic heating from moist convection initiated and/or enhanced by the solenoid circulation subsequently leads to the formation of a mesoscale convective vortex that further organizes and amplifies moist convection while propagating eastward along the mei-yu front. The downward branch of the MPS, on the other hand, leads to the suppression of precipitation over the plains during the daytime. The impacts of this regional MPS on the rainfall diurnal variations are further attested to by another idealized WRF simulation that uses fixed lateral boundary conditions.
Probabilistic Wind Gust Forecasting Using Nonhomogeneous Gaussian Regression
Authors: Thorarinsdottir Thordis L. , Johnson Matthew S.
Published: August 2011

A joint probabilistic forecasting framework is proposed for maximum wind speed, the probability of gust, and, conditional on gust being observed, the maximum gust speed in a setting where only the maximum wind speed forecast is available. The framework employs the nonhomogeneous Gaussian regression (NGR) statistical postprocessing method with appropriately truncated Gaussian predictive distributions. For wind speed, the distribution is truncated at zero, the location parameter is a linear function of the wind speed ensemble forecast, and the scale parameter is a linear function of the ensemble variance. The gust forecasts are derived from the wind speed forecast using a gust factor, and the predictive distribution for gust speed is truncated according to its definition. The framework is applied to 48-h-ahead forecasts of wind speed over the North American Pacific Northwest obtained from the University of Washington mesoscale ensemble. The resulting density forecasts for wind speed and gust speed are calibrated and sharp, and offer substantial improvement in predictive performance over the raw ensemble or climatological reference forecasts.
Can Lagrangian Extrapolation of Radar Fields Be Used for Precipitation Nowcasting over Complex Alpine Orography?
Authors: Mandapaka Pradeep V. , Germann Urs , Panziera Luca , Hering Alessandro
Published: August 2011

In this study, a Lagrangian radar echo extrapolation scheme (MAPLE) was tested for use in very short-term forecasting of precipitation over a complex orographic region. The high-resolution forecasts from MAPLE for lead times of 5 min–5 h are evaluated against the radar observations for 20 summer rainfall events by employing a series of categorical, continuous, and neighborhood evaluation techniques. The verification results are then compared with those from Eulerian persistence and high-resolution numerical weather prediction model [the Consortium for Small-scale Modeling model (COSMO2)] forecasts. The forecasts from the MAPLE model clearly outperformed Eulerian persistence forecasts for all the lead times, and had better skill compared to COSMO2 up to lead time of 3 h on average. The results also showed that the predictability achieved from the MAPLE model depends on the spatial structure of the precipitation patterns. This study is a first implementation of the MAPLE model over a complex Alpine region. In addition to comprehensive evaluation of precipitation forecast products, some open questions related to the nowcasting of rainfall over a complex terrain are discussed.
Prevalence, Characteristics, and Risk Factors of Elevated Triglyceride Levels in US Children
Authors: Christian Jennifer B. , Juneja Maneesh X. , Meadowcroft Amy M. , Borden Spencer , Lowe Kimberly A.
Published: August 2011

Limited information is available on the epidemiology of hypertriglyceridemia (HTG; 150-499 mg/dL) and severe HTG (SHTG; >500 mg/dL) in children. This study estimates the prevalence of HTG and SHTG, evaluates factors that may be associated with these conditions, and describes the use of dyslipidemic agents in children. The sample included children 12 to 19 years old who participated in National Health and Nutrition Examination Survey (NHANES) 2001-2008 (n = 3248) and children 5 to 19 years of age who were part of a large managed-care claims database in the United States (n = 65 258). Results from NHANES confirm the rarity of SHTG in the US pediatric population (ie, 0.2%). Factors statistically significantly associated with having HTG or SHTG in the claims database were being male, 12 to 19 years old, having high low-density lipoprotein (LDL), having low high-density lipoprotein (HDL), diabetes, and psychological disorders. Fibrates were the most commonly prescribed triglyceride-lowering agent among children with SHTG, followed by statins and Lovaza.
On the Relationship Between Differential Item Functioning and Item Difficulty
Authors: Santelices María Verónica , Wilson Mark
Published: August 2011

The relationship between differential item functioning (DIF) and item difficulty on the SAT is such that more difficult items tended to exhibit DIF in favor of the focal group (usually minority groups). These results were reported by Kulick and Hu, and Freedle and have been enthusiastically discussed by more recent literature. Examining the validity of the original reports of this systematic relationship is important so that we can move on to investigating more effectively its causes and the consequences associated to test score use. This article explores the hypothesis that the observed relationship between DIF and item difficulty observed in the SAT could be because of one of the following explanations: (a) the confounding of DIF and impact by the shortcomings of the standardization approach and/or (b) by random guessing. The relationship between DIF and item difficulty is examined using item response theory, which better controls for differences between impact and DIF than the standardization approach and also allows us to test the importance of guessing. The results obtained generally find evidence in support of the relationship between item difficulty and DIF suggesting that the phenomenon reported by earlier research is not a mere artifact of the statistical methodologies used to study DIF.
Examining Rounding Rules in Angoff-Type Standard-Setting Methods
Authors: Wyse Adam E. , Reckase Mark D.
Published: August 2011

This study investigates how different rounding rules and ways of providing Angoff standard-setting judgments affect cut-scores. A simulation design based on data from the National Assessment of Education Progress was used to investigate how rounding judgments to the nearest whole number (e.g., 0, 1, 2, etc.), nearest 0.05, or nearest two decimal places for individual items or clusters of items affected cut-scores for individual panelists and a group of panelists across four different pools of items. For the simulated ratings from a group of panelists, the recovery of the cut-scores was examined using the mean and the median. Results showed that rounding to nearest whole number had the potential to produce fairly large statistical biases in cut-score estimates. Biases were less when judgments were simulated across cluster of items. The largest biases were found at the advanced cut-score, but the greatest potential changes in the percentage of students that would be above the cut-score were found for the basic cut-score. Rounding to the nearest 0.05 or nearest two decimals places did not have a large impact on cut-score estimates and had little effect on the percentage of students above the cut-score. Implications for policy and future standard-setting practices are provided.
Investigating Flash memory wear levelling and execution modes
Authors: Zertal Soraya , Harrison Peter G
Published: August 2011

The impact of wear levelling on a Flash storage package and its access operations’ execution modes is investigated. First, a simple, static logical-to-physical mapping function is proposed and its implied wear levelling is assessed for different distributions of addresses, covering both uniform access and hotspots, as well as the Flash chip utilization within the whole package. Second, for each access mode, different preemptive and non-preemptive priority schemes are considered with a range of IO arrival rates, using Poisson-, Erlang- and Pareto-based arrival processes. The analysis of the impact of the execution modes on the performance of the Flash memory is undertaken using a hardware simulator. The results show clearly the good wear levelling obtained by the mapping functions, even in the presence of hotspots. In addition, the impact of the chosen execution mode on the whole storage package for each IO workload type is assessed, both qualitatively and quantitatively.
The Intersection of War and Politics
Authors: Marsh Kevin P.
Published: August 2011

This study examines the decision-making process of the George W. Bush administration which led to the decision in late 2006 to order the Iraq troop surge. The study analyzes whether the bureaucratic politics model of foreign policy decision making can accurately explain the events of the case. The study seeks to further test the explanatory power and descriptive accuracy of the bureaucratic politics model, while also attaining a more textured, academic understanding of the decision-making process leading to the Iraq troop surge. The decision to order the troop surge in Iraq is one of the more important decisions in post-9/11 U.S. foreign policy and continues to impact U.S. strategy in Iraq, Afghanistan, and overall military doctrine. Finally, the author endeavors to contribute to the further development and refinement of the bureaucratic politics model of foreign policy decision making.
Impact of Residency Programs on Professional Socialization of Newly Licensed Registered Nurses
Authors: Kramer Marlene , Maguire Patrica , Halfer Diana , Brewer Barbara , Schmalenberg Claudia
Published: August 2011

Do Nurse Residency Programs (NRPs) reflect the professional socialization process? Residency facilitators in 34 Magnet hospitals completed Residency Program Questionnaires constructed to reflect the goals, themes, components, and strategies of the professional socialization process described in the literature. NRPs in 4 hospitals exemplified the complete two-stage (role transition and role/community integration) process. In 14 hospitals, NRPs were of sufficient length and contained components that reflected the professional socialization process. In 16 hospitals, NRPs exemplified the “becoming” role transition stage. What components are most effective in the professional socialization of new graduate nurses? A total of 907 new and experienced nurses, nurse managers, and educators working on clinical units with confirmed healthy work environments in 20 Magnet hospitals with additional “excellence designations” were interviewed. Components identified as most instrumental were precepted experience, reflective seminars, skill acquisition, reflective practice sessions, evidence-based management projects, and clinical coaching–mentoring sessions. Suggestions for improvement of NRPs are offered.