bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Variant PfCRT Isoform Can Contribute to
Plasmodium falciparum
Resistance to the First-Line Partner Drug Piperaquine
Authors: Dhingra Satish K. , Redhi Devasha , Combrinck Jill M. , Yeo Tomas , Okombo John , Henrich Philipp P. , Cowell Annie N. , Gupta Purva , Stegman Matthew L. , Hoke Jonathan M. , Cooper Roland A. , Winzeler Elizabeth , Mok Sachel , Egan Timothy J. , Fidock David A. 
Published: May 2017

ABSTRACT

Current efforts to reduce the global burden of malaria are threatened by the rapid spread throughout Asia of
Plasmodium falciparum
resistance to artemisinin-based combination therapies, which includes increasing rates of clinical failure with dihydroartemisinin plus piperaquine (PPQ) in Cambodia. Using zinc finger nuclease-based gene editing, we report that addition of the C101F mutation to the chloroquine (CQ) resistance-conferring PfCRT Dd2 isoform common to Asia can confer PPQ resistance to cultured parasites. Resistance was demonstrated as significantly higher PPQ concentrations causing 90% inhibition of parasite growth (IC
90
) or 50% parasite killing (50% lethal dose [LD
50
]). This mutation also reversed Dd2-mediated CQ resistance, sensitized parasites to amodiaquine, quinine, and artemisinin, and conferred amantadine and blasticidin resistance. Using heme fractionation assays, we demonstrate that PPQ causes a buildup of reactive free heme and inhibits the formation of chemically inert hemozoin crystals. Our data evoke inhibition of heme detoxification in the parasite’s acidic digestive vacuole as the primary mode of both the
bis
-aminoquinoline PPQ and the related 4-aminoquinoline CQ. Both drugs also inhibit hemoglobin proteolysis at elevated concentrations, suggesting an additional mode of action. Isogenic lines differing in their
pfmdr1
copy number showed equivalent PPQ susceptibilities. We propose that mutations in PfCRT could contribute to a multifactorial basis of PPQ resistance in field isolates.

IMPORTANCE
The global agenda to eliminate malaria depends on the continued success of artemisinin-based combination therapies (ACTs), which target the asexual blood stages of the intracellular parasite
Plasmodium
. Partial resistance to artemisinin, however, is now established in Southeast Asia, exposing the partner drugs to increased selective pressure.
Plasmodium falciparum
resistance to the first-line partner piperaquine (PPQ) is now spreading rapidly in Cambodia, resulting in clinical treatment failures. Here, we report that a variant form of the
Plasmodium falciparum
chloroquine resistance transporter, harboring a C101F mutation edited into the chloroquine (CQ)-resistant Dd2 isoform prevalent in Asia, can confer PPQ resistance in cultured parasites. This was accompanied by a loss of CQ resistance. Biochemical assays showed that PPQ, like CQ, inhibits the detoxification of reactive heme that is formed by parasite-mediated catabolism of host hemoglobin. We propose that novel PfCRT variants emerging in the field could contribute to a multigenic basis of PPQ resistance.
Rationally Designed TLR4 Ligands for Vaccine Adjuvant Discovery
Authors: Gregg Kelsey A. , Harberts Erin , Gardner Francesca M. , Pelletier Mark R. , Cayatte Corinne , Yu Li , McCarthy Michael P. , Marshall Jason D. , Ernst Robert K. 
Published: May 2017

ABSTRACT

Adjuvant properties of bacterial cell wall components like MPLA (monophosphoryl lipid A) are well described and have gained FDA approval for use in vaccines such as Cervarix. MPLA is the product of chemically modified lipooligosaccharide (LOS), altered to diminish toxic proinflammatory effects while retaining adequate immunogenicity. Despite the virtually unlimited number of potential sources among bacterial strains, the number of useable compounds within this promising class of adjuvants are few. We have developed bacterial enzymatic combinatorial chemistry (BECC) as a method to generate rationally designed, functionally diverse lipid A. BECC removes endogenous or introduces exogenous lipid A-modifying enzymes to bacteria, effectively reprogramming the lipid A biosynthetic pathway. In this study, BECC is applied within an avirulent strain of
Yersinia pestis
to develop structurally distinct LOS molecules that elicit differential Toll-like receptor 4 (TLR4) activation. Using reporter cell lines that measure NF-κB activation, BECC-derived molecules were screened for the ability to induce a lower proinflammatory response than
Escherichia coli
LOS. Their structures exhibit varied, dose-dependent, TLR4-driven NF-κB activation with both human and mouse TLR4 complexes. Additional cytokine secretion screening identified molecules that induce levels of tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) comparable to the levels induced by phosphorylated hexa-acyl disaccharide (PHAD). The lead candidates demonstrated potent immunostimulation in mouse splenocytes, human primary blood mononuclear cells (PBMCs), and human monocyte-derived dendritic cells (DCs). This newly described system allows directed programming of lipid A synthesis and has the potential to generate a diverse array of TLR4 agonist candidates.

IMPORTANCE
There is an urgent need to develop effective vaccines against infectious diseases that continue to be major causes of morbidity and mortality worldwide. Making effective vaccines requires selecting an adjuvant to strengthen an appropriate and protective immune response. This work describes a practical method, bacterial enzymatic combinatorial chemistry (BECC), for generating functionally diverse molecules for adjuvant use. These molecules were analyzed in cell culture for their ability to initiate immune stimulatory activity. Several of the assays described herein show promising
in vitro
cytokine production and costimulatory molecule expression results, suggesting that the BECC molecules may be useful in future vaccine preparations.
Primary care services co-located with Emergency Departments across a UK region: early views on their development
Authors: Ablard Suzanne , O’Keeffe Colin , Ramlakhan Shammi , Mason Suzanne M 
Published: May 2017

BackgroundCo-location of primary care services with Emergency Departments (ED) is one initiative aiming to reduce the burden on EDs of patients attending with non-urgent problems. However, the extent to which these services are operating within or alongside EDs is not currently known.This study aimed to create a typology of co-located primary care services in operation across Yorkshire and Humber (Y&H) as well as identify early barriers and facilitators to their implementation and sustainability.MethodsA self-report survey was sent to the lead consultant or other key contact at 17 EDs in the Y&H region to establish the extent and configuration of co-located primary care services. Semi-structured interviews were then conducted with urgent and unscheduled care stakeholders across five hospital sites to explore the barriers and facilitators to the formation and sustainability of these services.ResultsThirteen EDs completed the survey and interviews were carried out with four ED consultants, one ED nurse and three general practitioners (GPs). Three distinct models were identified: ‘Primary Care Services Embedded within the ED’ (seven sites), ‘Co-located Urgent Care Centre’ (two sites) and ‘GP out-of-hours’ (nine sites). Qualitative data were analysed using framework analysis. Four interview themes emerged (justification for the service, level of integration, referral processes and sustainability) highlighting some of the challenges in implementing these co-located primary care services.ConclusionCreating a service within or alongside the ED in which GPs can use their distinct skills and therefore add value to the existing skill mix of ED staff is an important consideration when setting up these systems. Effective triage arrangements should also be established to ensure appropriate patients are referred to GPs. Further research is required to identify the full range of models nationally and to carry out a rigorous assessment of their impact.
HER2 Reactivation through Acquisition of the HER2 L755S Mutation as a Mechanism of Acquired Resistance to HER2-targeted Therapy in HER2+ Breast Cancer
Authors: Xu Xiaowei , De Angelis Carmine , Burke Kathleen A. , Nardone Agostina , Hu Huizhong , Qin Lanfang , Veeraraghavan Jamunarani , Sethunath Vidyalakshmi , Heiser Laura M. , Wang Nicholas , Ng Charlotte K.Y. , Chen Edward S. , Renwick Alexander , Wang Tao , Nanda Sarmistha , Shea Martin , Mitchell Tamika , Rajendran Mahitha , Waters Ian , Zabransky Daniel J. , Scott Kenneth L. , Gutierrez Carolina , Nagi Chandandeep , Geyer Felipe C. , Chamness Gary C. , Park Ben H. , Shaw Chad A. , Hilsenbeck Susan G. , Rimawi Mothaffar F. , Gray Joe W. , Weigelt Britta , Reis-Filho Jorge S. , Osborne C. Kent , Schiff Rachel 
Published: May 2017

AbstractPurpose: Resistance to anti-HER2 therapies in HER2+ breast cancer can occur through activation of alternative survival pathways or reactivation of the HER signaling network. Here we employed BT474 parental and treatment-resistant cell line models to investigate a mechanism by which HER2+ breast cancer can reactivate the HER network under potent HER2-targeted therapies.Experimental Design: Resistant derivatives to lapatinib (L), trastuzumab (T), or the combination (LR/TR/LTR) were developed independently from two independent estrogen receptor ER+/HER2+ BT474 cell lines (AZ/ATCC). Two derivatives resistant to the lapatinib-containing regimens (BT474/AZ-LR and BT474/ATCC-LTR lines) that showed HER2 reactivation at the time of resistance were subjected to massive parallel sequencing and compared with parental lines. Ectopic expression and mutant-specific siRNA interference were applied to analyze the mutation functionally. In vitro and in vivo experiments were performed to test alternative therapies for mutant HER2 inhibition.Results: Genomic analyses revealed that the HER2L755S mutation was the only common somatic mutation gained in the BT474/AZ-LR and BT474/ATCC-LTR lines. Ectopic expression of HER2L755S induced acquired lapatinib resistance in the BT474/AZ, SK-BR-3, and AU565 parental cell lines. HER2L755S-specific siRNA knockdown reversed the resistance in BT474/AZ-LR and BT474/ATCC-LTR lines. The HER1/2–irreversible inhibitors afatinib and neratinib substantially inhibited both resistant cell growth and the HER2 and downstream AKT/MAPK signaling driven by HER2L755S in vitro and in vivo.Conclusions: HER2 reactivation through acquisition of the HER2L755S mutation was identified as a mechanism of acquired resistance to lapatinib-containing HER2-targeted therapy in preclinical HER2-amplified breast cancer models, which can be overcome by irreversible HER1/2 inhibitors. Clin Cancer Res; 23(17); 5123–34. ©2017 AACR.
Head-to-Head Comparison of Inflammation and Neovascularization in Human Carotid Plaques
Authors: Demeure Fabian , Bouzin Caroline , Roelants Véronique , Bol Anne , Verhelst Robert , Astarci Parla , Gerber Bernhard L. , Pouleur Anne-Catherine , Pasquet Agnès , de Meester Christophe , Vanoverschelde Jean-Louis J. , Vancraeynest David 
Published: May 2017

Background—
Inflammation and intraplaque neovascularization are acknowledged to be 2 features of plaque vulnerability, although their temporal expression and their respective value in predicting clinical events are poorly understood. To determine their respective temporal associations, we conducted a comprehensive assessment of inflammation and intraplaque neovascularization in the carotid plaque of symptomatic and asymptomatic patients.

Methods and Results—

Thirty patients with severe carotid stenosis underwent
18
F-fluorodeoxyglucose-positron emission tomography/computed tomographic imaging. Plaque
18
F-fluorodeoxyglucose-uptake, indicative of inflammation, was measured by calculating the target:background ratio. The presence of intraplaque neovascularization during contrast-enhanced ultrasound was judged semiquantitatively; low-grade contrast enhancement (CE) suggested its absence, and high-grade CE, the presence of neovascularization. Carotid surgery was performed 1.6±1.8 days after completing both imaging modalities in all patients, and the presence of macrophages and neovessels was quantified by immunohistochemistry. We identified a significant correlation between the target:background ratio and macrophage quantification (
R
=0.78;
P
<0.001). The number of vessels was also significantly higher in carotid plaque with high-CE (
P
<0.001). Surprisingly, immunohistochemistry showed that high-CE and vessel number were neither associated with an elevated target:background ratio (
P
=0.28 and
P
=0.60, respectively) nor macrophage infiltration (
P
=0.59 and
P
=0.40, respectively). Finally, macrophage infiltration and target:background ratio were higher in the carotid plaque of symptomatic patients (
P
=0.021 and
P
=0.05, respectively), whereas CE grade and the presence of neovessels were not.

Conclusions—
Inflammation and intraplaque neovascularization are not systematically associated in carotid plaques, suggesting a temporal separation between the 2 processes. Inflammation seems more pronounced when symptoms are present. These data highlight the challenges that face any imaging strategy designed to assess plaque vulnerability.
Enhanced Detection of Edema in Malignant Anterior Circulation Stroke (EDEMA) Score
Authors: Ong Charlene Jennifer , Gluckstein Jeffrey , Laurido-Soto Osvaldo , Yan Yan , Dhar Rajat , Lee Jin-Moo 
Published: May 2017

Background and Purpose—
Rapid recognition of those at high risk for malignant edema after stroke would facilitate triage for monitoring and potential surgery. Admission data may be insufficient for accurate triage decisions. We developed a risk prediction score using clinical and radiographic variables within 24 hours of ictus to better predict potentially lethal malignant edema.

Methods—
Patients admitted with diagnosis codes of cerebral edema and ischemic stroke, NIHSS score (National Institute of Health Stroke Score) of ≥8 and head computed tomographies within 24 hours of stroke onset were included. Primary outcome of potentially lethal malignant edema was defined as death with midline shift ≥5 mm or decompressive hemicraniectomy. We performed multivariate analyses on data available within 24 hours of ictus. Bootstrapping was used to internally validate the model, and a risk score was constructed from the results.

Results—
Thirty-three percent of 222 patients developed potentially lethal malignant edema. The final model C statistic was 0.76 (confidence interval, 0.68–0.82) in the derivation cohort and 0.75 (confidence interval, 0.72–0.77) in the bootstrapping validation sample. The EDEMA score (Enhanced Detection of Edema in Malignant Anterior Circulation Stroke) was developed using the following independent predictors: basal cistern effacement (=3); glucose ≥150 (=2); no tPA (tissue-type plasminogen activator) or thrombectomy (=1), midline shift >0 to 3 (=1), 3 to 6 (=2), and 6 to 9 (=4); >9 (=7); and no previous stroke (=1). A score over 7 was associated with 93% positive predictive value.

Conclusions—
The EDEMA score identifies patients at high risk for potentially lethal malignant edema. Although it requires external validation, this scale could help expedite triage decisions in this patient population.
ASPECTS (Alberta Stroke Program Early CT Score) Measurement Using Hounsfield Unit Values When Selecting Patients for Stroke Thrombectomy
Authors: Mokin Maxim , Primiani Christopher T. , Siddiqui Adnan H. , Turk Aquilla S. 
Published: May 2017

Background and Purpose—
The ASPECTS (Alberta Stroke Program Early CT Score) is a quantitate score that measures the extent of early ischemic changes. Our aim was to investigate how measurement of ASPECTS using Hounsfield unit (HU) values on initial noncontrast head computerized tomography (CT) correlates with the extent of final infarct on follow-up imaging.

Methods—
Cases of acute stroke from the middle cerebral artery M1 occlusion in which complete recanalization (TICI [Thrombolysis in Cerebral Infarction] 3) was achieved were included for analysis. Using HU ratio (HU affected/HU control hemisphere) and HU difference (HU control−HU affected hemisphere) values, ASPECTS was measured on initial CT imaging and correlated with final ASPECTS at 24 hours. The study cohort consisted of 41 patients with acute stroke from the M1 occlusion. The mean time from stroke symptoms onset to baseline head CT imaging was 264 minutes and from CT to TICI 3 recanalization was 142 minutes.

Results—

HU ratio within the 0.94 to 0.96 ranges showed the highest correlation coefficient and lowest mean and median errors with the final ASPECTS. The difference of 2.0 HU between the 2 hemispheres demonstrated the higher correlation coefficient (
r
=0.71;
P
<0.0001) and the lowest mean and median absolute errors (1.4 and 1, respectively).

Conclusions—
We established a simple algorithm for rapid and accurate assessment of ASPECTS on baseline CT imaging to predict the extent of final stroke in patients with emergent large vessel occlusion who undergo endovascular revascularization.
Hemorrhage Risk of Brain Arteriovenous Malformations During Pregnancy and Puerperium in a North American Cohort
Authors: Porras Jose L. , Yang Wuyang , Philadelphia Eunice , Law Jody , Garzon-Muvdi Tomas , Caplan Justin M. , Colby Geoffrey P. , Coon Alexander L. , Tamargo Rafael J. , Huang Judy 
Published: May 2017

Background and Purpose—
Conclusions reached in existing literature about risk of arteriovenous malformation (AVM) hemorrhage during pregnancy are controversial. This study compares the risk of hemorrhage in pregnant and nonpregnant female patients with AVM in a North American cohort.

Methods—
We retrospectively reviewed female patients with AVM evaluated from 1990 to 2015. Exposure period for pregnancy and puerperium was calculated as 40 and 6 weeks, respectively, for each full-term pregnancy and 6 weeks for each abortion. Hemorrhage events and patient-years were calculated during an exposure period (pregnancy and puerperium), and a nonexposure period defined as either the interval from birth until AVM obliteration or until last follow-up after subtracting exposure period. Poisson rate ratio test was used to compare rate of hemorrhage between exposure and nonexposure periods.

Results—

For 270 female patients with AVM, mean age was 35.0±19.6 years, and race distribution was white (n=165, 61.1%), black (n=59, 21.9%), Hispanic (n=9, 3.3%), Asian (n=6, 2.2%), and other (n=31, 11.5%). From 191 total pregnancies occurring before AVM obliteration, there were 175 (91.6%) term deliveries and 16 (8.4%) abortions. Overall annual hemorrhage rate for 149 total hemorrhages during an average of 11 097 patient-years was 1.34%. There were 140 hemorrhages in nonexposed women and 9 hemorrhages in pregnant women, translating to an annual hemorrhage rate of 1.3% in nonpregnant women versus 5.7% in pregnant women (
P
<0.001). Identical analysis for reproductive age patients (15–50) demonstrated a rate of 1.3% versus 7.0% (
P
<0.001).

Conclusions—
Our results conflict with those from a recent study describing no increased rate of rupture during pregnancy. This difference may reflect unique population attributes influencing brain AVM hemorrhage during pregnancy.
Super-Clausius–Clapeyron Scaling of Extreme Hourly Convective Precipitation and Its Relation to Large-Scale Atmospheric Conditions
Authors: Lenderink G. , Barbero R. , Loriaux J. M. , Fowler H. J. 
Published: May 2017

AbstractPresent-day precipitation–temperature scaling relations indicate that hourly precipitation extremes may have a response to warming exceeding the Clausius–Clapeyron (CC) relation; for the Netherlands the dependency on surface dewpoint temperature follows 2 times the CC relation (2CC). The authors’ hypothesis—as supported by a simple physical argument presented here—is that this 2CC behavior arises from the physics of convective clouds. To further investigate this, the large-scale atmospheric conditions accompanying summertime afternoon precipitation events are analyzed using surface observations combined with a regional reanalysis. Events are precipitation measurements clustered in time and space. The hourly peak intensities of these events again reveal a 2CC scaling with the surface dewpoint temperature. The temperature excess of moist updrafts initialized at the surface and the maximum cloud depth are clear functions of surface dewpoint, confirming the key role of surface humidity on convective activity. Almost no differences in relative humidity and the dry temperature lapse rate were found across the dewpoint temperature range, supporting the theory that 2CC scaling is mainly due to the response of convection to increases in near-surface humidity, while other atmospheric conditions remain similar. Additionally, hourly precipitation extremes are on average accompanied by substantial large-scale upward motions and therefore large-scale moisture convergence, which appears to accelerate with surface dewpoint. Consequently, most hourly extremes occur in precipitation events with considerable spatial extent. Importantly, this event size appears to increase rapidly at the highest dewpoint temperature range, suggesting potentially strong impacts of climatic warming.
The Structure, Evolution, and Dynamics of a Nocturnal Convective System Simulated Using the WRF-ARW Model
Authors: Blake Benjamin T. , Parsons David B. , Haghi Kevin R. , Castleberry Stephen G. 
Published: May 2017

AbstractPrevious studies have documented a nocturnal maximum in thunderstorm frequency during the summer across the central United States. Forecast skill for these systems remains relatively low and the explanation for this nocturnal maximum is still an area of active debate. This study utilized the WRF-ARW Model to simulate a nocturnal mesoscale convective system that occurred over the southern Great Plains on 3–4 June 2013. A low-level jet transported a narrow corridor of air above the nocturnal boundary layer with convective instability that exceeded what was observed in the daytime boundary layer. The storm was elevated and associated with bores that assisted in the maintenance of the system. Three-dimensional variations in the system’s structure were found along the cold pool, which were examined using convective system dynamics and wave theory. Shallow lifting occurred on the southern flank of the storm. Conversely, the southeastern flank had deep lifting, with favorable integrated vertical shear over the layer of maximum CAPE. The bore assisted in transporting high-CAPE air toward its LFC, and the additional lifting by the density current allowed for deep convection to occur. The bore was not coupled to the convective system and it slowly pulled away, while the convection remained in phase with the density current. These results provide a possible explanation for how convection is maintained at night in the presence of a low-level jet and a stable boundary layer, and emphasize the importance of the three-dimensionality of these systems.