bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Sensitive and Selective Basal Plane Pyrolytic Graphite Electrode Modified with 1,4‐Naphthoquinone/MWCNT for Simultaneous Determination of Dopamine, Ascorbate and Urate
Authors: Oliveira Ananda Xavier , Silva Saimon Moraes , Leite Fernando Roberto Figueiredo , Kubota Lauro Tatsuo , Damos Flavio Santos , de Cássia Silva Luz Rita 
Published: February 2013

AbstractThe present work describes the development of a highly selective and sensitive voltammetric sensor for dopamine (DA), ascorbic acid (AA) and uric acid (UA) using a basal plane pyrolytic graphite (BPPG) electrode modified with 1,4‐naphthoquinone (NQ) adsorbed on multiwalled carbon nanotubes (MWCNT). The modified electrode showed an excellent electrochemical activity towards the oxidations of DA, AA and UA. Three well‐defined voltammetric peaks, in a buffered solution at pH 7.5, were obtained by differential pulse voltammetry (DPV) at −0.050, 0.145 and 0.270 V vs. Ag/AgCl for AA, DA and UA, respectively. Linear calibration plots were obtained in the range of 10–70 nmol L−1 for DA, 40–280 µmol L−1 for AA and 2–14 µmol L−1 for UA, with detection limits of 3 nmol L−1, 1.9 µmol L−1 and 0.1 µmol L−1, respectively. The sensor was successfully applied in human urine samples and the results showed that the modified electrode has no interferences from urine sample.
Electrochemical Behavior of Caffeic Acid Assayed with Gold Nanoparticles/Graphene Nanosheets Modified Glassy Carbon Electrode
Authors: Zhang Yanli , Liu Yanpei , He Jiemei , Pang Pengfei , Gao Yuntao , Hu Qiufen 
Published: February 2013

AbstractA gold nanoparticle (AuNP) and graphene nanosheet (GN) modified glassy carbon electrode (GCE) is proposed as voltammetric sensor for caffeic acid assay. The sensor exhibits a surface‐confined and reversible process for oxidation of caffeic acid revealed by cyclic voltammetry. The results show more favorable electron transfer kinetics than the bare GCE. The linear response of the sensor is from 5×10−7 to 5×10−5 M with a detection limit of 5×10−8 M (S/N=3). The AuNP/GN nanocomposite shows more favorable electrochemical activity and should be a kind of more robust and advanced functional material, which provides a promising platform for electrochemical sensors and biosensors. The method was successfully applied to detect caffeic acid in pharmaceutical tablets with satisfactory results.
Confounding effects of coral growth and high SST variability on skeletal Sr/Ca: Implications for coral paleothermometry
Authors: Grove Craig A. , Kasper Sebastian , Zinke Jens , Pfeiffer Miriam , Garbe‐Schönberg Dieter , Brummer Geert‐Jan A. 
Published: February 2013

AbstractMassive corals offer continuous records of climate locked within their skeleton, with the most commonly applied paleo‐thermometer being Sr/Ca. Recently, however, problems with Sr/Ca thermometry indicate that the intrinsic variance of single‐core Sr/Ca time series differs between cores. Here, we compare the Sr/Ca records and growth parameters of two Porites lutea colonies sampled from the same reef zone, 0.72 km apart, with two gridded SST datasets, ERSST and HadISST, off NE Madagascar. Specifically, we address seasonal and interannual variability as well as trend differences between records over the same 43 year period. The two gridded SST datasets showed strong seasonality and weak positive ENSO anomalies on a slow 43 year warming trend at significantly different rates. Both the coral Sr/Ca records showed the same clear seasonality and similar amplitudes in SST. However, on interannual timescales, they displayed diverging 43 year Sr/Ca trends and opposite responses to weak ENSO anomalies. Moreover, their growth response also differed as one coral showed increasing extension/calcification rates and Sr/Ca ratios (cooling) over the 43 years, while the other coral showed decreasing extension/calcification rates and Sr/Ca ratios (warming). Further, during positive ENSO events, the calcification rates of the two corals were negatively correlated, while skeletal density anomalies were opposite. Possible explanations to why these corals are so different may be related to the corals growth response to SST changes. The growth response of individual corals to increasing SST seems to be opposite, which in turn are likely related to biological factors. Consequently, coral growth responses explain much of the inter‐colony Sr/Ca variability.
Coevolution of nonlinear trends in vegetation, soils, and topography with elevation and slope aspect: A case study in the sky islands of southern Arizona
Authors: Pelletier Jon D. , Barron‐Gafford Greg A. , Breshears David D. , Brooks Paul D. , Chorover Jon , Durcik Matej , Harman Ciaran J. , Huxman Travis E. , Lohse Kathleen A. , Lybrand Rebecca , Meixner Tom , McIntosh Jennifer C. , Papuga Shirley A. , Rasmussen Craig , Schaap Marcel , Swetnam Tyson L. , Troch Peter A. 
Published: February 2013

AbstractFeedbacks among vegetation dynamics, pedogenesis, and topographic development affect the “critical zone”—the living filter for Earth's hydrologic, biogeochemical, and rock/sediment cycles. Assessing the importance of such feedbacks, which may be particularly pronounced in water‐limited systems, remains a fundamental interdisciplinary challenge. The sky islands of southern Arizona offer an unusually well‐defined natural experiment involving such feedbacks because mean annual precipitation varies by a factor of five over distances of approximately 10 km in areas of similar rock type (granite) and tectonic history. Here we compile high‐resolution, spatially distributed data for Effective Energy and Mass Transfer (EEMT: the energy available to drive bedrock weathering), above‐ground biomass, soil thickness, hillslope‐scale topographic relief, and drainage density in two such mountain ranges (Santa Catalina: SCM; Pinaleño: PM). Strong correlations exist among vegetation‐soil‐topography variables, which vary nonlinearly with elevation, such that warm, dry, low‐elevation portions of these ranges are characterized by relatively low above‐ground biomass, thin soils, minimal soil organic matter, steep slopes, and high drainage densities; conversely, cooler, wetter, higher elevations have systematically higher biomass, thicker organic‐rich soils, gentler slopes, and lower drainage densities. To test if eco‐pedo‐geomorphic feedbacks drive this pattern, we developed a landscape evolution model that couples pedogenesis and topographic development over geologic time scales, with rates explicitly dependent on vegetation density. The model self‐organizes into states similar to those observed in SCM and PM. Our results highlight the potential importance of eco‐pedo‐geomorphic feedbacks, mediated by soil thickness, in water‐limited systems.
Rapid differentiation of isomeric lipids by photodissociation mass spectrometry of fatty acid derivatives
Authors: Pham Huong T. , Trevitt Adam J. , Mitchell Todd W. , Blanksby Stephen J. 
Published: February 2013

RATIONALEBoth traditional electron ionization and electrospray ionization tandem mass spectrometry have demonstrated limitations in the unambiguous identification of fatty acids. In the former case, high electron energies lead to extensive dissociation of the radical cations from which little specific structural information can be obtained. In the latter, conventional collision‐induced dissociation (CID) of even‐electron ions provides little intra‐chain fragmentation and thus few structural diagnostics. New approaches that harness the desirable features of both methods, namely radical‐driven dissociation with discrete energy deposition, are thus required.METHODSHerein we describe the derivatization of a structurally diverse suite of fatty acids as 4‐iodobenzyl esters (FAIBE). Electrospray ionization of these derivatives in the presence of sodium acetate yields abundant [M + Na]+ ions that can be mass‐selected and subjected to laser irradiation (λ = 266 nm) on a modified linear ion‐trap mass spectrometer.RESULTSPhotodissociation (PD) of the FAIBE derivatives yields abundant radical cations by loss of atomic iodine and in several cases selective dissociation of activated carbon–carbon bonds (e.g., at allylic positions) are also observed. Subsequent CID of the [M + Na – I]•+ radical cations yields radical‐directed dissociation (RDD) mass spectra that reveal extensive carbon–carbon bond dissociation without scrambling of molecular information.CONCLUSIONSBoth PD and RDD spectra obtained from derivatized fatty acids provide a wealth of structural information including the position(s) of unsaturation, chain‐branching and hydroxylation. The structural information obtained by this approach, in particular the ability to rapidly differentiate isomeric lipids, represents a useful addition to the lipidomics tool box. Copyright © 2013 John Wiley & Sons, Ltd.
Training effects on motor–cognitive dual-task performance in older adults
Authors: Wollesen Bettina , Voelcker-Rehage Claudia 
Published: February 2013

Abstract
This systematic review investigated whether healthy older adults benefit from training interventions in motor–cognitive dual-task (DT) situations and which specific aspects of the intervention and/or task selection contribute to training benefits. Training effects were analysed with regard to the training programme (e.g., general ST or DT training) and task conditions (e.g., standing or walking, complexity of secondary cognitive task). Literature was searched via OVIDsp (Medline, EMBASE, PsycINFO). DT studies were included by the following criteria: (1) investigation of at least one motor task, (2) assessment of DT performance outcomes on standing or walking, (3) conduction of an intervention, and (4) investigation of older adults in an experimental–control group design or an old–young comparison. Thirteen studies met all inclusion criteria. Four types of interventions were identified: (1) general single-task (ST) motor training, (2) specific ST motor training, (3) general DT training, and (4) task-related (specific) DT training. For DT standing conditions only DT interventions improved motor performance, whereas DT walking also benefits by ST training. Most benefits on motor and cognitive performance seem to be reached by DT training interventions whereas a GST produced lowest effects. Thus, balance orientated motor and cognitive DT performance in healthy older adults can be improved by performance related exercises. Furthermore, to reach beneficial effects, it seems necessary that the training intervention includes a certain level of exercise load such as rising difficulties, appropriate intensity and duration, a certain level of task specificity, and variable task prioritization. The transfer of training effects into everyday situations needs to be further investigated.
Bone Fracture Exacerbates Murine Ischemic Cerebral Injury
Authors: Degos Vincent , Maze Mervyn , Vacas Susana , Hirsch Jan , Guo Yi , Shen Fanxia , Jun Kristine , van Rooijen Nico , Gressens Pierre , Young William L. , Su Hua 
Published: February 2013

Abstract

Background:
Bone fracture increases alarmins and proinflammatory cytokines in the blood, and provokes macrophage infiltration and proinflammatory cytokine expression in the hippocampus. We recently reported that stroke is an independent risk factor after bone surgery for adverse outcome; however, the impact of bone fracture on stroke outcome remains unknown. We tested the hypothesis that bone fracture, shortly after ischemic stroke, enhances stroke-related injuries by augmenting the neuroinflammatory response.

Methods:
Tibia fracture (bone fracture) was induced in mice one day after permanent occlusion of the distal middle cerebral artery (stroke). High-mobility-group box chromosomal protein-1 (HMGB1) was tested to mimic the bone fracture effects. HMGB1 neutralizing antibody and clodrolip (macrophage depletion) were tested to attenuate the bone fracture effects. Neurobehavioral function (n = 10), infarct volume, neuronal death, and macrophages/microglia infiltration (n = 6–7) were analyzed after 3 days.

Results:
We found that mice with both stroke and bone fracture had larger infarct volumes (mean percentage of ipsilateral hemisphere ± SD: 30±7% vs.12±3%, n = 6, P < 0.001), more severe neurobehavioral dysfunction, and more macrophages/microglia in the periinfarct region than mice with stroke only. Intraperitoneal injection of HMGB1 mimicked, whereas neutralizing HMGB1 attenuated, the bone fracture effects and the macrophage/microglia infiltration. Depleting macrophages with clodrolip also attenuated the aggravating effects of bone fracture on stroke lesion and behavioral dysfunction.

Conclusions:
These novel findings suggest that bone fracture shortly after stroke enhances stroke injury via augmented inflammation through HMGB1 and macrophage/microglia infiltration. Interventions to modulate early macrophage/microglia activation could be therapeutic goals to limit the adverse consequences of bone fracture after stroke.
Emerging markers in cardiovascular disease: Where does angiotensin‐converting enzyme 2 fit in?
Authors: Patel Sheila K , Velkoska Elena , Burrell Louise M 
Published: February 2013

Summary

The renin–angiotensin system plays a major role in the pathophysiology of cardiovascular disease (CVD). The enzyme angiotensin‐converting enzyme (ACE) converts angiotensin (Ang) I into the vasoconstrictor AngII and was thought, until recently, to be the main effector of the system.

The enzyme ACE2, discovered in 2000, can counterbalance the effects of ACE through degradation of AngII and generation of Ang‐(1–7). Angiotensin‐converting enzyme 2 is abundantly expressed in the heart and localized to the endothelial cells of coronary vessels and smooth muscle cells. Its catalytically active ectodomain undergoes shedding, resulting in ACE2 in the circulation.

There are 10 studies to date that have measured circulating ACE2 activity in humans, including in healthy subjects and those with heart failure, Type 1 diabetes, implantable cardioverter/defibrillator, elderly subjects undergoing emergency orthopaedic surgery and kidney transplant patients. The results suggest that circulating ACE2 activity may be a marker of CVD, with low levels in healthy individuals and increased levels in those with cardiovascular risk factors or disease. Whether increased plasma ACE2 activity reflects increased synthesis from tissue ACE2 mRNA or increased shedding of tissue ACE2 remains to be determined.

Angiotensin‐converting enzyme 2 is located on the X‐chromosome and circulating ACE2 levels are higher in men than in women.

Large clinical studies in CVD are needed to more precisely clarify the role of ACE2 as a biomarker of CVD, determine the prognostic significance of circulating ACE2 activity and assess whether the measurement of ACE2 will improve CVD risk prediction.
Vitamin D supplementation reduces airway hyperresponsiveness and allergic airway inflammation in a murine model
Authors: Agrawal T. , Gupta G. K. , Agrawal D. K. 
Published: February 2013

SummaryBackgroundAsthma is a chronic disease associated with airway hyperresponsiveness (AHR), airway obstruction and airway remodelling. NF‐κB is a transcriptional factor that regulates and co‐ordinates the expression of various inflammatory genes. The NF‐κB subunits, p50 and Rel‐A, are translocated to the nucleus by importin α3 and importin α4. There is growing evidence that vitamin D is a potent immunomodulator. However, the evidence for beneficial or adverse effects of vitamin D in asthma is still unclear.ObjectiveIn this study, we examined the effect of vitamin D status on AHR, airway inflammation and cytokines in the bronchoalveolar lavage fluid (BALF) in a murine model of allergic asthma.MethodsFemale BALB/c mice were fed with special vitamin D‐deficient or vitamin D‐sufficient (2000 IU/kg) or vitamin D‐supplemented (10 000 IU/kg) diet for 13 weeks. Mice were sensitized and challenged with ovalbumin (OVA). The effect of vitamin D on lung histology, AHR, T regulatory cells (Tregs) and BALF cytokines was examined. The expression of importin‐α3 and Rel‐A in the lung of OVA‐sensitized mice was analysed using immunofluorescence.ResultsVitamin D deficiency was associated with higher AHR in OVA‐sensitized and challenged mice than those in vitamin D‐sufficient mice. This was accompanied with marked signs of airway remodelling, high BALF eosinophilia, increased BALF pro‐inflammatory cytokines, reduced BALF IL‐10 levels, reduced blood Tregs, increased expression of importin‐α3 and Rel‐A in the lung tissue. Vitamin D supplementation attenuated the pro‐inflammatory effects, but did not completely reverse the features of allergic airway inflammation.Conclusion and Clinical RelevanceVitamin D could be beneficial as an adjunct therapy in the treatment of allergic asthma.
Speed isn't everything: complex processing speed measures mask individual differences and developmental changes in executive control
Authors: Cepeda Nicholas J. , Blackwell Katharine A. , Munakata Yuko 
Published: February 2013

AbstractThe rate at which people process information appears to influence many aspects of cognition across the lifespan. However, many commonly accepted measures of ‘processing speed’ may require goal maintenance, manipulation of information in working memory, and decision‐making, blurring the distinction between processing speed and executive control and resulting in overestimation of processing speed contributions to cognition. This concern may apply particularly to studies of developmental change, as even seemingly simple processing speed measures may require executive processes to keep children and older adults on task. We report two new studies and a re‐analysis of a published study, testing predictions about how different processing speed measures influence conclusions about executive control across the lifespan. We find that the choice of processing speed measure affects the relationship observed between processing speed and executive control, in a manner that changes with age, and that choice of processing speed measure affects conclusions about development and the relationship among executive control measures. Implications for understanding processing speed, executive control, and their development are discussed.
An exploratory study of contrast agents for soft tissue visualization by means of high resolution X‐ray computed tomography imaging
Authors: PAUWELS E. , VAN LOO D. , CORNILLIE P. , BRABANT L. , VAN HOOREBEKE L. 
Published: February 2013

SummaryHigh resolution X‐ray computed tomography (CT), or microCT, is a promising and already widely used technique in various scientific fields. Also for histological purposes it has great potential. Although microCT has proven to be a valuable technique for the imaging of bone structures, the visualization of soft tissue structures is still an important challenge due to their low inherent X‐ray contrast. One way to achieve contrast enhancement is to make use of contrast agents. However, contrary to light and electron microscopy, knowledge about contrast agents and staining procedures is limited for X‐ray CT. The purpose of this paper is to identify useful X‐ray contrast agents for soft tissue visualization, which can be applied in a simple way and are also suited for samples larger than (1 cm)3. And 28 chemical substances have been investigated. All chemicals were applied in the form of concentrated aqueous solutions in which the samples were immersed. First, strips of green Bacon were stained to evaluate contrast enhancement between muscle and adipose tissue. Furthermore it was also tested whether the contrast agents remained fixed in the tissue after staining by re‐immersing them in water. Based on the results, 12 contrast agents were selected for further testing on postmortem mice hind legs, containing a variety of different tissues, including muscle, fat, bone, cartilage and tendons. It was evaluated whether the contrast agents allowed a clearer distinction between the different soft tissue structures present. Finally also penetration depth was measured. And 26 chemicals resulted in contrast enhancement between muscle and adipose tissue in the Bacon strips. Mercury(II)chloride (HgCl2), phosphotungstic acid (PTA), phosphomolybdic acid (PMA) and ammonium orthomolybdate ((NH4)2MoO4) remained fixed after re‐immersion in water. The penetration tests showed that potassium iodide (KI) and sodium tungstate can be most efficiently used for large samples of the order of several tens of cm3. PMA, PTA, HgCl2and also to a lesser extent Na2WO4and (NH4)2MoO4allowed a clearer distinction between the different soft tissue structures present.
General Dentist Characteristics Associated With Rural Practice Location
Authors: McKernan Susan C. , Kuthy Raymond A. , Kavand Golnaz 
Published: February 2013

AbstractPurposeTo examine whether there is a difference in the likelihood that a general dentist practices in a rural location based on individual characteristics, including dental school attended, birth state, practice arrangement, sex, and age.MethodsAll private practice, general dentists in Iowa were included in this study. Data were extracted from the year 2010 version of the Iowa Dentist Tracking System, which monitors practice patterns of active dentists. Rurality of primary office location, categorized using Rural‐Urban Commuting Area codes, served as the outcome variable. Chi‐square tests and multivariable logistic regression were used to explain associations between rural practice location and dentist characteristics.FindingsFifteen percent of the state's population resided in isolated small rural towns, but only 8% of general dentists practiced here. Approximately 17% of dentists in isolated small rural towns were age 40 or younger, compared to 32% of dentists in urban areas. Among male dentists, those who were born in Iowa (P = .002) were older (P = .020), and graduated from dental schools other than the University of Iowa (P = .009) were more likely to practice in rural areas than were their counterparts. Conversely, among female dentists, solo practice (P = .016) was the only variable significantly associated with rural practice location.ConclusionsThe dentist workforce in rural areas of Iowa is dominated by older males who were born in Iowa. As this generation retires and increasing numbers of women enter the profession, state policy makers and planners will need to monitor changing trends in the rural workforce.