bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of duplex DNA and RNA by dangling ends studied by free energy simulations
Authors: Kara Mahmut , Zacharias Martin
Published: August 2013

Single unpaired nucleotides at the end of double‐stranded nucleic acids, termed dangling ends, can contribute to duplex stability. Umbrella sampling free energy simulations of dangling cytosine and guanine nucleotides at the end of duplex and single stranded RNA and DNA molecules have been used to investigate the molecular origin of dangling end effects. In unrestraint simulations, the dangling end nucleotides stayed close to placements observed in experimental structures. Calculated free energy contributions associated with the presence of dangling nucleotides were in reasonable agreement with experiment predicting the general trend of a more stabilizing effect of purine vs. pyrimidine dangling ends. In addition, the calculations indicate a more significant stabilizing effect of dangling ends at the 5′‐end vs. 3′‐end in case of DNA and the opposite trend in case of RNA. Both electrostatic and van der Waals interactions contribute to the duplex stabilizing effect of dangling end nucleotides. The free energy simulation scheme could also be used to design dangling end nucleotides that result in enhanced duplex stabilization. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 418–427, 2014.
Effects of organic modifier and temperature on the enantiomeric separation of several azole drugs using supercritical fluid chromatography and the Chiralpak AD column
Authors: Toribio L. , Bernal J. L. , Martín M. T. , Bernal J. , del Nozal M. J.
Published: August 2013

The effects of organic modifier and temperature on the enantioseparation of 10 triazoles and eight imidazoles, using supercritical fluid chromatography with the Chiralpak AD column, have been investigated in this work. For this purpose four different organic modifiers (methanol, ethanol, 2‐propanol and acetonitrile) were evaluated. Only in the case of two compounds could the enantiomeric separation not be achieved with any of the modifiers tested; the rest of compounds were baseline or partially resolved with at least one of the modifiers. The alcohol‐type modifiers provided the best results in terms of retention time and resolution. In general, retention increased in the order methanol < ethanol < 2‐propanol; moreover it was possible to establish a relationship between the retention and the number of aromatic rings and dioxolane groups in the molecule, that is, the higher the number is, the higher the retention time. From the study of the temperature effect, the enthalpy–entropy compensation was demonstrated for all the compounds, except for bifonazole using methanol and miconazole using acetonitrile. This suggested that both analytes are enantiomerically resolved through different mechanisms. Copyright © 2013 John Wiley & Sons, Ltd.
Transcatheter treatment of iatrogenic brachiocephalic‐jugular arteriovenous fistula and aortopulmonary artery fistula: A case report
Authors: Makonkawkeyoon Krit , Thonghong Tasaluck , Woragidpoonpol Surin , Srimahachota Suphot , Lertsapcharoen Pornthep
Published: August 2013

Iatrogenic arteriovenous fistula is not a common complication of central venous catheterization. Duct occluder devices have been developed for patent ductus arteriosus occlusions but they may be used for arteriovenous fistula closures. We report a case of iatrogenic brachiocephalic‐jugular and aortopulmonary artery fistulas after central venous catheter insertion. The fistulas were successfully managed with duct occluder devices. Due to increasing number of central venous catheterizations, physicians should be aware of this uncommon complication. Transcatheter closing of brachiocephalic‐jugular and aortopulmonary artery fistulas by duct occluder devices seems to be a safe and feasible form of treatment. © 2013 Wiley Periodicals, Inc.
Cryptogenic left main thrombosis: Successful mechanical clot retrieval with a self‐expanding trapping device
Authors: Otto Sylvia , Mayer Thomas E. , Figulla Hans R.
Published: August 2013

We present the case of a 52‐year‐old male with ST‐segment elevation myocardial infarction due to a spontaneous large left main thrombosis, without any angiographic evidence for coronary artery disease. After multiple unsuccessful attempts of thrombaspiration the large clot was mechanically retrieved by a flow restoration device that was primarily made for intracranial interventions. Intravascular ultrasound revealed marginal lumen narrowing after the intervention, but the final coronary angiogram showed a patent left main and there was no relevant stenosis remaining. © 2013 Wiley Periodicals, Inc.
How to limit radial artery spasm during percutaneous coronary interventions: The spasmolytic agents to avoid spasm during transradial percutaneous coronary interventions (SPASM3) study
Authors: Rosencher Julien , Chaïb Aurès , Barbou Franck , Arnould Marc‐Antoine , Huber Arthur , Salengro Emmanuel , Jégou Arnaud , Allouch Philippe , Zuily Stéphane , Mihoub Fadila , Varenne Olivier
Published: August 2013

Aims: To compare the efficacy of three vasodilators in preventing radial artery spasm (RAS) in patients undergoing transradial percutaneous coronary interventions (PCI). Methods and Results: 731 patients were randomized to receive diltiazem 5 mg, verapamil 2.5 mg, or isosorbide dinitrate (ISDN) 1 mg before coronary intervention. RAS occurred in 20.1% in the whole population and was significantly reduced by verapamil and ISDN compared to diltiazem (16.2, 17.2, and 26.6%, respectively; P < 0.006). There was also a trend towards less severe pain (more than 8 on a numerical scale from 0 [no pain] to 10 [maximal pain]), and less severe RAS (complete catheter blockage or severe pain), among patients treated by verapamil compared to ISDN and diltiazem (1.3% vs. 2.8% vs. 2.9%, P = 0.43 and 5.1% vs. 6.2% vs. 9.5%, respectively, P = 0.13). No difference was found between the three vasodilators in terms of crossover or safety events. Female gender, failure at first attempt to access the radial artery, emergency procedures, and the use of diltiazem were independent predictors of RAS. Conclusion: Verapamil and ISDN considerably reduce the incidence of RAS compared to diltiazem during transradial PCI. © 2013 Wiley Periodicals, Inc.
Transcatheter patch closure of an atrial septal defect of sinus venosus type using the immediate release patch
Authors: Franke Jennifer , Bertog Stefan C. , Sideris Eleftherios B. , Hofmann Ilona , Wunderlich Nina , Hornung Marius , Sievert Horst
Published: August 2013

Following promising preclinical studies, we report our first clinical experience with transcatheter closure of an atrial septal defect of sinus venosus type in a 65‐year‐old patient using the Immediate Release Patch. © 2015 Wiley Periodicals, Inc.
Efficacy and safety of renal denervation in elderly patients with resistant hypertension
Authors: Ziegler Ann‐Kathrin , Bertog Stefan , Kaltenbach Benjamin , Id Dani , Franke Jennifer , Hofmann Ilona , Vaskelyte Laura , Sievert Horst
Published: August 2013

Background: Catheter‐based renal sympathetic denervation (RD) causes significant blood pressure (BP) reductions in patients with resistant hypertension (rHTN). However, hypertensive elderly patients reportedly have a lower sympathetic tone than younger patients and a BP lowering effect of RD in this population has not yet been demonstrated. The purpose of this study was to assess the efficacy and safety of RD in elderly patients. Methods: We reviewed all consecutive patients aged ≥ 75 years (mean: 78 years) with rHTN treated with RD. Twenty‐four patients were included in this prospective study. Office and ambulatory BPs were assessed at baseline and 6‐months follow‐up. Primary endpoint was the change in office systolic BP at 6 months. Results: Baseline mean office BP was 173/86 ± 21/13 mm Hg. Baseline 24‐hr mean ambulatory BP, available in 22 patients, was 158/80 ± 20/13 mm Hg. Baseline creatinine was 1.0 ± 0.18 mg/dl and mean number of antihypertensive agents at baseline 4.3 ± 1.4. No device‐ or procedure‐related adverse events occurred. At 6‐months follow‐up, the mean office BP decreased by 19/11 ± 29/16 mm Hg (P < 0.01 compared to baseline). Mean systolic 24 hr ambulatory BP, available in 17 patients, decreased by 9/5 ± 13/13 mm Hg. Antihypertensive medications could be reduced in nine patients. Furthermore, renal function was not impaired. Conclusion: According to our findings, a similar magnitude of BP reduction as reported in previous trials can be expected in elderly patients. Elderly patients with rHTN should not be excluded from renal denervation. © 2015 Wiley Periodicals, Inc.
Angiographic fate of side branch dissections in bifurcation lesions treated with a provisional single stenting strategy: A post‐hoc analysis of the international multicenter randomized DEBIUT study
Authors: Belkacemi Anouar , Stella Pieter R. , Chunlai Shao , Uiterwijk Marcelle , Ali Danish , Agostoni Pierfrancesco
Published: August 2013

Background

The provisional single stenting strategy is currently the preferred treatment strategy in bifurcation lesions. However, in case of nonflow limiting side branch (SB) dissections, it is not clear whether outcomes may be inferior to coronaries without a SB dissection, whether it can be safe to leave a SB dissection untreated, and whether bail‐out SB stenting provides benefits over conservative treatment.

Methods

Bifurcation lesions treated with a provisional single stenting in the randomized DEBIUT were screened according to the presence or absence of SB dissections. Additional treatment (with possible stent implantation) or conservative management was left to the discretion of the operator.

Results

Out of the 117 lesions included, 18 (15.4%) angiographic SB dissections were seen following intervention (type A = 3, B = 7, C = 6, D/E = 2), 9 (50%) were treated with additional stenting, while 9 (50%) were left untreated. At 6‐month follow up, all dissections that were left untreated were healed. The late‐luminal loss was similar (P = 0.33) between patients without dissection (0.11 mm [−0.22 to 0.43 mm]) and with dissection (0.29 mm [−0.28 to 0.88 mm]). The late‐luminal loss was nonsignificantly lower (P = 0.40) in the nonstented dissection group (−0.01 mm [−0.33 to 0.87 mm]), than in the stented dissection group (0.41 mm [−0.20 to 0.97 mm]), while binary restenosis was 1 (13%) and 2 (25%), respectively.

Conclusion

Coronary SB dissections have similar 6‐month angiographic late‐luminal loss as lesions without SB dissection, with complete angiographic healing of the dissections. Moreover, this study suggests that in case of a dissection, if operators consider it safe not to stent the dissection, this can lead to a satisfactory result at mid‐term follow‐up. © 2013 Wiley Periodicals, Inc.
Echocardiographic predictors of cardiac erosion after amplatzer septal occluder placement
Authors: Amin Zahid
Published: August 2013

The risk of erosion after Amplatzer septal occluder (ASO) device placement in atrial septal defects is well described. Aortic rim deficiency and use of over‐sized device increase the risk of erosion. This study attempts to describe device characteristics, anatomical features and echocardiographic predictors that increase the risk of erosion. Methods: From 2005 through 2012, 12 new cases, with nine confirmed and three suspected device erosions where pre‐procedural, intra‐procedural, and/or post‐procedural echocardiograms were available and, were reviewed. Following parameters were evaluated: ASD location (high or low), rims deficiency and consistency, septal mal‐alignment, dynamic nature of the defect; device edge relationship toward the transverse sinus (TS), atrial free wall tenting and the size of the defect compared with the size of the device used for closure. Results: We found poor posterior rim consistency, aortic rim absence (in multiple views) and absent aortic rim at O degree in 100% of the patients. Septal mal‐alignment and dynamic ASD was present in nearly 50% of the cases. The device was over‐sized in three patients only. A 26‐mm device was the most common device that resulted in erosion. In cases, where patient had experienced bloody pericardial effusion and the device was in place, device tenting in the TS was observed. Surgical explantation of the device confirmed presence of erosion in all cases. Conclusion: Aortic rim absence in multiple views, poor posterior rim consistency, septal mal‐alignment, and dynamic ASD appear to be factors where erosion risk increases significantly. A thorough assessment of the device edge by echocardiography in short‐axis may show device tenting of the atrial free wall into the TS. This finding should be a strong indictor to recommend surgical removal of device after occurrence of pericardial effusion. © 2013 Wiley Periodicals, Inc.
Copper(II) Triflate Catalyzed Allylic Arylation of Allylic Alcohols: Direct and Selective Access to C‐Allylanilines
Authors: Chen Ke , Chen Houguang Jeremy , Wong Jonathan , Yang Jinglei , Pullarkat Sumod A.
Published: August 2013

Copper(II) triflate was used as a simple and commercially available catalyst in the direct amination of allylic alcohols with anilines to provide C‐allylanilines. A wide range of functional groups were tolerated under the reaction conditions, and the products were obtained regioselectivity without the need of an activator. A detailed mechanistic investigation was undertaken. The efficacy of this protocol was demonstrated in the conversion of the 2‐allylanilines into substituted quinolines through an oxidative cycloaddition reaction.
The Genetics of Dilated Cardiomyopathy: A Prioritized Candidate Gene Study of LMNA, TNNT2, TCAP, and PLN
Authors: Hirtle‐Lewis Marika , Desbiens Katia , Ruel Isabelle , Rudzicz Nicholas , Genest Jacques , Engert James C. , Giannetti Nadia
Published: August 2013

Background

Dilated cardiomyopathy (DCM), which is characterized by left ventricular enlargement and systolic dysfunction, is divided into cases with a clear predisposing condition (eg, hypothyroidism, chemotherapeutic agents, alcoholism, ischemia) and those of unknown cause (idiopathic DCM). Many cases (20%–35%) of DCM are familial, implicating a genetic contribution to the etiology. More than 30 genes have been identified, many involving “private” mutations not shared among families. Evidence suggests that nonfamilial cases also have a genetic predisposition, again involving many genes. The goal of this study was to identify mutations in genes associated with DCM in a Québec study sample including familial and nonfamilial DCM cases.

Hypothesis

A prioritized gene study conducted within a framework for the classification of identified genetic variants could yield etiological information even in the absence of family data.

Methods

We sequenced 4 previously identified genes: lamin A/C (LMNA), cardiac troponin T type 2 (TNNT2), titin‐cap (TCAP), and phospholamban (PLN).

Results

We discovered a nonsense mutation in the LMNA gene and a frameshift mutation in the TNNT2 gene, as well as other clinically significant variants that were not observed in publicly available databases or in Québec‐based controls. PLN was sequenced to investigate a previously published promoter variant. However, our data confirm that this variant does not have a causal role in DCM.

Conclusions

Despite high locus and allele heterogeneity, we demonstrate that a prioritized gene study, combined with next‐generation exome‐sequencing data, can be fruitful for the identification of DCM mutations.
Differences in Coronary Blood Flow in Aortic Regurgitation and Systemic Arterial Hypertension Have Implications for Diastolic Blood Pressure Targets: A Systematic Review and Meta‐Analysis
Authors: Rabkin Simon W.
Published: August 2013

The objective was to evaluate coronary blood flow (CBF) in patients with systemic arterial hypertension (HTN) and to compare it with CBF in patients with aortic regurgitation (AR). A systematic literature search was conducted using the reference terms “coronary blood flow” and either “aortic regurgitation” or “hypertension.” The selection criteria included CBF measurement in a concomitant control group, except studies evaluating CBF with aortic‐valve replacement surgery. Twenty‐two studies met the inclusion criteria. There were 318 persons with HTN, with 185 controls; and 102 persons with AR, with 144 controls. Despite an overall increase in CBF in HTN, CBF per gram of left ventricular mass was significantly (P < 0.0001) reduced. In contrast, CBF per gram of left ventricular mass was significantly (P = 0.004) increased in AR. Aortic regurgitation was associated with a significant (P < 0.0001) increase in CBF during systole and away from diastole, in contrast to persons with HTN. Aortic‐valve replacement reversed the increase in systolic CBF. These data suggest that patients with HTN are more vulnerable than patients with AR to lower diastolic blood pressure (DBP), because resting CBF is compromised in HTN. Furthermore, patients with HTN may not compensate for DBP reductions by shifting CBF to systole, such as can occur with the low DBP in AR. Lower DBP in patients with AR cannot be used to justify treating patients with HTN to similar DBP because of the dramatic differences in CBF between the 2 conditions.
Methamphetamine‐Associated Cardiomyopathy
Authors: Won Sekon , Hong Robert A. , Shohet Ralph V. , Seto Todd B. , Parikh Nisha I.
Published: August 2013

Methamphetamine and related compounds are now the second most commonly used illicit substance worldwide, after cannabis. Reports of methamphetamine‐associated cardiomyopathy (MAC) are increasing, but MAC has not been well reviewed. This analysis of MAC will provide an overview of the pharmacology of methamphetamine, historical perspective and epidemiology, a review of case and clinical studies, and a summary of the proposed mechanisms for MAC. Clinically, many questions remain, including the appropriate therapeutic interventions for MAC, the incidence and prevalence of cardiac pathology in methamphetamine users, risk factors for developing MAC, and prognosis of these patients. In conclusion, recognition of the significance of MAC among physicians and other medical caregivers is important given the growing use of methamphetamine and related stimulants worldwide.
Neoadjuvant chemotherapy followed by concurrent chemoradiation for locoregionally advanced nasopharyngeal carcinoma
Authors: Kong Lin , Hu Chaosu , Niu Xiaoshuang , Zhang Youwang , Guo Ye , Tham Ivan W. K. , Lu Jiade Jay
Published: August 2013

BACKGROUND

The authors studied the efficacy of neoadjuvant chemotherapy, consisting of a taxane, cisplatin, and 5‐fluorouracil (5‐FU) (the TPF regimen) followed by concurrent chemoradiation, in 2 separately designed and synchronously executed phase 2 trials for stage III and IVA/IVB nasopharyngeal cancer (NPC).

METHODS

Patients with newly diagnosed NPC were accrued to 2 trials, 1 for patients with stage III disease and the other for patients with IVA/IVB disease. All patients received TPF (docetaxel 75 mg/m2, cisplatin 75 mg/m2, and 5‐FU 2500 mg/m2 every 3 weeks for 3 cycles) followed by cisplatin 40 mg/m2 per week concurrently with either 3‐dimentional conformal radiation therapy or intensity‐modulated radiation therapy.

RESULTS

From January 2007 to July 2011, 52 eligible patients with stage III NPC and 64 eligible patients with nonmetastatic stage IV NPC were accrued. With a median follow‐up of 32.9 months, the 3‐year overall survival rates were 94.8% (95% confidence interval [CI], 87.6%‐100%) and 90.2% (95% CI, 81.8%‐98.6%) for the stage III NPC group and the IVA/IVB NPC group, respectively. The 3‐year progression‐free survival, distant metastasis‐free survival, and local progression‐free survival rates were 78.2% (95% CI, 64.6%‐91.8%), 90.5% (95% CI, 79.7%‐100%), and 93.9%(87.1%‐100%), respectively, for patients with stage III NPC and 85.1% (95% CI, 75.1%‐95.1%), 88% (95% CI, 78.6%‐97.4%), and 100%, respectively, for patients with stage IVA/IVB NPC. The most common severe (grade 3/4) hematologic and nonhematologic adverse events were neutropenia (64 patients; 55.2%) and nausea/vomiting (23 patients; 19.8%).

CONCLUSIONS

Neoadjuvant TPF followed by concurrent chemoradiation was well tolerated and produced encouraging outcomes in patients with locally advanced NPC in this hypothesis‐generating study. The authors concluded that randomized controlled trials are warranted to definitively confirm this aggressive and potentially efficacious strategy. Cancer 2013;119:4111–4118. © 2013 American Cancer Society.
Interior Least Tern (Sternula antillarum) breeding distribution and ecology: implications for population‐level studies and the evaluation of alternative management strategies on large, regulated rivers
Authors: Lott Casey A. , Wiley Robert L. , Fischer Richard A. , Hartfield Paul D. , Scott J. Michael
Published: August 2013

Interior Least Terns (Sternula antillarum) (ILT) are colonial, fish‐eating birds that breed within active channels of large sand bed rivers of the Great Plains and in the Lower Mississippi Valley. Multipurpose dams, irrigation structures, and engineered navigation systems have been present on these rivers for many decades. Despite severe alteration of channels and flow regimes, regulation era floods have remained effective at maintaining bare sandbar nesting habitat on many river segments andILTpopulations have been stable or expanding since they were listed as endangered in 1985. We usedILTbreeding colony locations from 2002 to 2012 and dispersal information to identify 16 populations and 48 subpopulations. More than 90% ofILTand >83% of river km with suitable nesting habitat occur within the two largest populations. However, replicate populations remain throughout the entire historical, geophysical, and ecological range ofILT. Rapid colonization of anthropogenic habitats in areas that were not historically occupied suggests metapopulation dynamics. The highest likelihood of demographic connectivity amongILTpopulations occurs across the Southern Plains and the Lower Mississippi River, which may be demographically connected with Least Tern populations on the Gulf Coast. Paired ecological and bird population models are needed to test whether previously articulated threats limitILTpopulation growth and to determine if management intervention is necessary and where. Given current knowledge, the largest sources of model uncertainty will be: (1) uncertainty in relationships between high flow events and subsequent sandbar characteristics and (2) uncertainty regarding the frequency of dispersal among population subunits. We recommend research strategies to reduce these uncertainties.
Metathesis Reactions: Recent Trends and Challenges
Authors: Deraedt Christophe , d'Halluin Martin , Astruc Didier
Published: August 2013

Metathesis reactions are now essential for the synthesis of complex organic molecules; a large variety of useful materials are available, and progress in this field is growing rapidly. Emphasis in this review on metathesis is placed on the recent developments of stereoselectivity aspects by using new families of molybdenum (Schrock type) and ruthenium (Grubbs type) catalysts for olefin metathesis. Recent progress in alkyne metathesis catalysts (Fürstner type) and their properties and impressive synthetic applications are highlighted as well as new terminal alkyne metathesis catalysts (Tamm type). The various strategies involved in recovering the catalyst and removing metal impurities from products towards “green chemistry” are briefly reviewed. The relationship of olefin metathesis is shown with the alkyne metathesis reaction that was exploited by Fürstner, with alkane metathesis that was achieved by using surface organometallic chemistry and highlighted by Basset, and with the use of classic organometallic catalysts by the Goldman and Brookhart groups. Finally, recent developments in polymer chemistry that involve stereochemical control, low polydispersities, and applications are summarized.
Sensitive Stripping Determination of Cadmium(II) and Lead(II) on Disposable Graphene Modified Screen‐Printed Electrode
Authors: Huangfu Chao , Fu Liang , Li Yuzhi , Li Xueling , Du Haijun , Ye Jianshan
Published: August 2013

In the present work, a sensitive, facile and disposable sensing platform for trace analysis of heavy metal ions was developed at the Bi modified graphene‐poly(sodium 4‐styrenesulfonate) composite film screen printed electrode (GR/PSS/Bi/SPE). The GR/PSS/Bi/SPE improved sensitivity and linearity due to the functionalization of graphene with negatively charged PSS providing more absorbing sites. The detection limit of the GR/PSS/Bi/SPE is found to be 0.042 µg L−1 for Cd2+ and 0.089 µg L−1 for Pb2+ with linear responses of Cd2+ and Pb2+ in the range of 0.5–120 µg L−1. Finally, the practical application was confirmed in real water with satisfactory results.
Electrochemical Determination of the Anticancer Herbal Drug Shikonin at a Nanostructured Poly(hydroxymethylated‐3,4‐ethylenedioxythiophene) Modified Electrode
Authors: Wu Liping , Lu Limin , Zhang Long , Xu Jingkun , Zhang Kaixin , Wen Yangping , Duan Xuemin , Yang Fan
Published: August 2013

A simple and sensitive method is described for the electrochemical determination of shikonin, a widely used anti‐tumoral agent, based on its electrochemical oxidation at a nanostructured poly(hydroxymethylated‐3,4‐ethylenedioxy‐thiophene) (PEDOT‐MeOH) electrode, which was fabricated by a facile electropolymerization method. Compared with bare and poly(3,4‐ethylenedioxythiophene) (PEDOT) electrodes, the PEDOT‐MeOH film exhibited a distinctly higher activity for the electrooxidation of shikonin. The PEDOT‐MeOH electrode showed a wide linear response for shikonin in the concentration range from 1.0 nM to 10.0 µM with detection limit of 0.3 nM. Furthermore, the PEDOT‐MeOH electrode displayed high stability, good reproducibility and high sensitivity for the detection of shikonin.
Antibiotic Detection in Urine Using Electrochemical Sensors Based on Vertically Aligned Carbon Nanotubes
Authors: Moraes Fernando C. , Silva Tiago A. , Cesarino Ivana , Lanza Marcos R. V. , Machado Sergio A. S.
Published: August 2013

A sensitive way to determine levofloxacin using a sensor based on vertical aligned carbon nanotubes is described. The morphology and the electrochemical performance of the electrodes were characterised by atomic force microscopy, cyclic voltammetry and square wave voltammetry. A scan‐rate study and electrochemical impedance spectroscopy showed that the levofloxacin oxidation product is adsorbed on the electrode surface. Differential pulse voltammetry in phosphate‐buffer solution allowed the development of a method to determine levofloxacin levels in the range of 1.0–10.0 µmol L−1, with a detection limit of 75.2 nmol L−1. The proposed sensor was successfully applied in the determination of levofloxacin in urine, and the obtained results were in full agreement with those from the HPLC procedure.
Fullerene‐β‐Cyclodextrin Conjugate Based Electrochemical Sensing Device for Ultrasensitive Detection of p‐Nitrophenol
Authors: Rather Jahangir Ahmad , Debnath Pradip , De Wael Karolien
Published: August 2013

The article describes the use of a fullerene (C60)‐β‐cyclodextrin conjugate, synthesized via 1,3‐dipolar cycloaddition, for the ultrasensitive electrochemical detection of p‐nitrophenol. This conjugate was successfully immobilized on the surface of a glassy carbon electrode and the developed device showed high activity towards p‐nitrophenol due to the synergetic effect of C60, the latter becoming highly conductive upon reduction. The determination of p‐nitrophenol was performed by using square wave voltammetry over a concentration range from 2.8×10−9 mol L−1 to 4.2×10−7 mol L−1 and the detection limit was calculated to be 1.2×10−9 mol L−1.
Bi‐Directional Electrocatalytic Detection of Dopamine at an Electrode Modified with Ferrocene‐Filled Carbon Nanotube Peapods
Authors: Cheng Huiming , Guan Lunhui , Shi Zujin , Zhu Zhiwei , Gu Zhennan , Li Meixian
Published: August 2013

A glassy carbon electrode (GCE) was modified with nanopeapods formed by ferrocene filled single‐walled carbon nanotubes (Fc@SWNTs). The modified electrode showed bi‐directional electrocatalysis toward dopamine (DA), which suggested a synergistic effect of ferrocene and carbon nanotubes. Bi‐directional detection of DA was realized based on the modified electrode.
Van Allen Probes observation of localized drift resonance between poloidal mode ultra‐low frequency waves and 60 keV electrons
Authors: Claudepierre S. G. , Mann I. R. , Takahashi K. , Fennell J. F. , Hudson M. K. , Blake J. B. , Roeder J. L. , Clemmons J. H. , Spence H. E. , Reeves G. D. , Baker D. N. , Funsten H. O. , W. Friedel R. H. , Henderson M. G. , Kletzing C. A. , Kurth W. S. , MacDowall R. J. , Smith C. W. , Wygant J. R.
Published: August 2013

We present NASA Van Allen Probes observations of wave‐particle interactions between magnetospheric ultra‐low frequency (ULF) waves and energetic electrons (20–500 keV) on 31 October 2012. The ULF waves are identified as the fundamental poloidal mode oscillation and are excited following an interplanetary shock impact on the magnetosphere. Large amplitude modulations in energetic electron flux are observed at the same period (≈ 3 min) as the ULF waves and are consistent with a drift‐resonant interaction. The azimuthal mode number of the interacting wave is estimated from the electron measurements to be ~40, based on an assumed symmetric drift resonance. The drift‐resonant interaction is observed to be localized and occur over 5–6 wave cycles, demonstrating peak electron flux modulations at energies ~60 keV. Our observation clearly shows electron drift resonance with the fundamental poloidal mode, the energy dependence of the amplitude and phase of the electron flux modulations providing strong evidence for such an interaction. Significantly, the observation highlights the importance of localized wave‐particle interactions for understanding energetic particle dynamics in the inner magnetosphere, through the intermediary of ULF waves.
Earthquake early warning for southern Iberia: A P wave threshold‐based approach
Authors: Carranza M. , Buforn E. , Colombelli S. , Zollo A.
Published: August 2013

The south of the Iberian Peninsula is a region in which large, damaging earthquakes occur separated by long time intervals. An example was the great 1755 Lisbon earthquake (intensity Imax = X) which occurred SW of San Vicente Cape (SW Iberian Peninsula). Due to this risk of damaging earthquakes, the implementation of Earthquake Early Warning System (EEWS) technologies is of considerable interest. With the aim of investigating the feasibility of an EEWS in this region of the Iberian Peninsula, empirical scaling relationships have been derived between the early warning parameters and the earthquake size and/or its potential damaging effects for this region. An appropriate and suitable strategy is proposed for an EEWS in the SW Iberian Peninsula, which takes into account the limitations of the existing seismological networks.
Scale dependence and frontal formation of nighttime medium‐scale traveling ionospheric disturbances
Authors: Yokoyama Tatsuhiro
Published: August 2013

Scale dependence of nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) is studied with the midlatitude ionosphere electrodynamics coupling model by changing initial perturbation scales. It is shown that both sporadic E (Es) layer and Perkins instabilities have the scale dependence that a shorter wavelength mode tends to stop growing within a shorter period, whereas a very long wavelength mode grows so slowly in the E region that it does not effectively seed the Perkins instability in the F region. As a result, the typical wavelength of MSTIDs (100–200 km) can be spontaneously generated without scale‐dependent forcing. It is also shown that long frontal structures of MSTIDs can be formed by the Pedersen polarization process along the wavefront of MSTIDs by which the wavefront is forced to be uniformly distributed.
Identifying health insurance predictors and the main reported reasons for being uninsured among US immigrants by legal authorization status
Authors: Vargas Bustamante Arturo , Chen Jie , Fang Hai , Rizzo John A. , Ortega Alexander N.
Published: August 2013

This study identifies differences in health insurance predictors and investigates the main reported reasons for lacking health insurance coverage between short‐stayed (≤10 years) and long‐stayed (>10 years) US immigrant adults to parse the possible consequences of the Affordable Care Act among immigrants by length of stay and documentation status. Foreign‐born adults (18‐64 years of age) from the 2009 California Health Interview Survey are the study population. Health insurance coverage predictors and the main reasons for being uninsured are compared across cohorts and by documentation status. A logistic‐regression two‐part multivariate model is used to adjust for confounding factors. The analyses determine that legal status is a strong health insurance predictor, particularly among long‐stayed undocumented immigrants. Immigration status is the main reported reason for lacking health insurance. Although long‐stayed documented immigrants are likely to benefit from the Affordable Care Act implementation, undocumented immigrants and short‐stayed documented immigrants may encounter difficulties getting health insurance coverage. Copyright © 2013 John Wiley & Sons, Ltd.
Effects of nitrogen limitation on hydrological processes in CLM4‐CN
Authors: Lee Eungul , Felzer Benjamin S. , Kothavala Zavareh
Published: August 2013

The role of nitrogen limitation on photosynthesis downregulation and stomatal conductance has a significant influence on evapotranspiration and runoff. In the current Community Land Model with coupled Carbon and Nitrogen cycles (CLM4‐CN), however, the carbon and water coupling in stomata is not linked to nitrogen limitation. We modify the incomplete linkages between carbon, nitrogen, and water, and examine how nitrogen limitation affects hydrological processes in CLM4‐CN. We then evaluate if the modification can improve the simulation of carbon and water fluxes. Applying the effects of nitrogen limitation on stomatal conductance significantly decreases leaf photosynthesis. It leads to a reduction in canopy transpiration, thereby increasing total runoff, mainly due to increasing subsurface runoff. More available soil water for vegetation from the reduced transpiration helps increase gross primary productivity (GPP) in the relatively moisture‐limited regions of grassland/steppe and savanna. However, in the tropics and boreal forest regions, changes in soil water by nitrogen limitation are insignificant, and GPP decreases directly by down‐regulated leaf photosynthesis. Decreasing canopy transpiration and increasing runoff from nitrogen limitation improve simulating latent heat flux and runoff by reducing high biases for latent heat flux in the tropics and low biases for runoff in the tropics and northern high latitudes. In addition, the CLM4‐CN with leaf‐level nitrogen limitation reduces model biases in tropical GPP. Nitrogen limitation on the leaf‐level significantly affects hydrological processes in CLM4‐CN and improves the simulation of carbon and water fluxes. This process should be included with other recent improvements to reduce model biases as much as possible.
Does convective aggregation need to be represented in cumulus parameterizations?
Authors: Tobin Isabelle , Bony Sandrine , Holloway Chris E. , Grandpeix Jean‐Yves , Sèze Geneviève , Coppin David , Woolnough Steve J. , Roca Rémy
Published: August 2013

Tropical deep convection exhibits a variety of levels of aggregation over a wide range of scales. Based on a multisatellite analysis, the present study shows at mesoscale that different levels of aggregation are statistically associated with differing large‐scale atmospheric states, despite similar convective intensity and large‐scale forcings. The more aggregated the convection, the dryer and less cloudy the atmosphere, the stronger the outgoing longwave radiation, and the lower the planetary albedo. This suggests that mesoscale convective aggregation has the potential to affect couplings between moisture and convection and between convection, radiation, and large‐scale ascent. In so doing, aggregation may play a role in phenomena such as “hot spots” or the Madden‐Julian Oscillation. These findings support the need for the representation of mesoscale organization in cumulus parameterizations; most parameterizations used in current climate models lack any such representation. The ability of a cloud system‐resolving model to reproduce observed relationships suggests that such models may be useful to guide attempts at parameterizations of convective aggregation.
Evaluation of a mPEG‐polyester‐based hydrogel as cell carrier for chondrocytes
Authors: Peng Sydney , Yang Shu‐Rui , Ko Chao‐Yin , Peng Yu‐Shiang , Chu I‐Ming
Published: August 2013

Temperature‐sensitive hydrogels are attractive alternatives to porous cell‐seeded scaffolds and is minimally invasive through simple injection and in situ gelling. In this study, we compared the performance of two types of temperature‐sensitive hydrogels on chondrocytes encapsulation for the use of tissue engineering of cartilage. The two hydrogels are composed of methoxy poly(ethylene glycol)‐ poly(lactic‐co‐valerolactone) (mPEG‐PVLA), and methoxy poly(ethylene glycol)‐poly(lactic‐ co‐glycolide) (mPEG‐PLGA). Osmolarity and pH were optimized through the manipulation of polymer concentration and dispersion medium. Chondrocytes proliferation in mPEG‐PVLA hydrogels was observed as well as accumulation of GAGs and collagen. On the other hand, chondrocytes encapsulated in mPEG‐PLGA hydrogels showed low viability and chondrogenesis. Also, mPEG‐PVLA hydrogel, which is more hydrophobic, retained physical integrity after 14 days while mPEG‐PLGA hydrogel underwent full degradation due to faster hydrolysis rate and more pronounced acidic self‐catalyzed degradation. The mPEG‐PVLA hydrogel can be furthered tuned by manipulation of molecular weights to obtain hydrogels with different swelling and degradation characteristics, which may be useful as producing a selection of hydrogels compatible with different cell types. Taken together, these results demonstrate that mPEG‐PVLA hydrogels are promising to serve as three‐dimensional cell carriers for chondrocytes and potentially applicable in cartilage tissue engineering. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 3311‐3319, 2013.
Increased Osteopontin Contributes to Inhibition of Bone Mineralization in FGF23-Deficient Mice
Authors: Yuan Quan , Jiang Yan , Zhao Xuefeng , Sato Tadatoshi , Densmore Michael , Schüler Christiane , Erben Reinhold G , McKee Marc D , Lanske Beate
Published: August 2013

Excessive FGF23 has been identified as a pivotal phosphaturic factor leading to renal phosphate-wasting and the subsequent development of rickets and osteomalacia. In contrast, loss of FGF23 in mice (Fgf23−/−) leads to high serum phosphate, calcium, and 1,25-vitamin D levels, resulting in early lethality attributable to severe ectopic soft-tissue calcifications and organ failure. Paradoxically, Fgf23−/− mice exhibit a severe defect in skeletal mineralization despite high levels of systemic mineral ions and abundant ectopic mineralization, an abnormality that remains largely unexplained. Through use of in situ hybridization, immunohistochemistry, and immunogold labeling coupled with electron microscopy of bone samples, we discovered that expression and accumulation of osteopontin (Opn/OPN) was markedly increased in Fgf23−/− mice. These results were confirmed by qPCR analyses of Fgf23−/− bones and ELISA measurements of serum OPN. To investigate whether elevated OPN levels were contributing to the bone mineralization defect in Fgf23−/− mice, we generated Fgf23−/−/Opn−/− double-knockout mice (DKO). Biochemical analyses showed that the hypercalcemia and hyperphosphatemia observed in Fgf23−/− mice remained unchanged in DKO mice; however, micro-computed tomography (µCT) and histomorphometric analyses showed a significant improvement in total mineralized bone volume. The severe osteoidosis was markedly reduced and a normal mineral apposition rate was present in DKO mice, indicating that increased OPN levels in Fgf23−/− mice are at least in part responsible for the osteomalacia. Moreover, the increased OPN levels were significantly decreased upon lowering serum phosphate by feeding a low-phosphate diet or after deletion of NaPi2a, indicating that phosphate levels contribute in part to the high OPN levels in Fgf23−/− mice. In summary, our results suggest that increased OPN is an important pathogenic factor mediating the mineralization defect and the alterations in bone metabolism observed in Fgf23−/− bones. © 2014 American Society for Bone and Mineral Research.
Female Mice Lacking Estrogen Receptor-Alpha in Osteoblasts Have Compromised Bone Mass and Strength
Authors: Melville Katherine M , Kelly Natalie H , Khan Sohaib A , Schimenti John C , Ross F Patrick , Main Russell P , van der Meulen Marjolein C H
Published: August 2013

Reduced bioavailability of estrogen increases skeletal fracture risk in postmenopausal women, but the mechanisms by which estrogen regulates bone mass are incompletely understood. Because estrogen signaling in bone acts, in part, through estrogen receptor alpha (ERα), mice with global deletion of ERα (ERαKO) have been used to determine the role of estrogen signaling in bone biology. These animals, however, have confounding systemic effects arising from other organs, such as increased estrogen and decreased insulin-like growth factor 1 (IGF-1) serum levels, which may independently affect bone. Mice with tissue-specific ERα deletion in chondrocytes, osteoblasts, osteocytes, or osteoclasts lack the systemic effects seen in the global knockout, but show that presence of the receptor is important for the function of each cell type. Although bone mass is reduced when ERα is deleted from osteoblasts, no study has determined if this approach reduces whole bone strength. To address this issue, we generated female osteoblast-specific ERαKO mice (pOC-ERαKO) by crossing mice expressing a floxed ERα gene (ERαfl/fl) with mice transgenic for the osteocalcin-Cre promoter (OC-Cre). Having confirmed that serum levels of estrogen and IGF-1 were unaltered, we focused on relating bone mechanics to skeletal phenotype using whole bone mechanical testing, microcomputed tomography, histology, and dynamic histomorphometry. At 12 and 18 weeks of age, pOC-ERαKO mice had decreased cancellous bone mass in the proximal tibia, vertebra, and distal femur, and decreased cortical bone mass in the tibial midshaft, distal femoral cortex, and L5 vertebral cortex. Osteoblast activity was reduced in cancellous bone of the proximal tibia, but osteoclast number was unaffected. Both femora and vertebrae had decreased whole bone strength in mechanical tests to failure, indicating that ERα in osteoblasts is required for appropriate bone mass and strength accrual in female mice. This pOC-ERαKO mouse is an important animal model that could enhance our understanding of estrogen signaling in bone cells in vivo. © 2014 American Society for Bone and Mineral Research.
Saturn chorus intensity variations
Authors: Menietti J. D. , Schippers P. , Katoh Y. , Leisner J. S. , Hospodarsky G. B. , Gurnett D. A. , Santolik O.
Published: August 2013

Whistler mode chorus plasma wave emissions have been observed at Saturn near the magnetic equator and the source region. During crossings of the magnetic equator along nearly constant L shells, the Cassini Radio and Plasma Wave Science Investigation often observes a local decrease in whistler mode intensity and bandwidth closest to the magnetic equator, where linear growth appears to dominate, with nonlinear structures appearing at higher latitudes and higher frequencies. We investigate linear growth rate using the Waves in a Homogeneous, Anisotropic, Multi‐component Plasma dispersion solver and locally observed electron phase space density measurements from the Electron Spectrometer sensor of the Cassini Plasma Spectrometer Investigation to determine the parameters responsible for the variation in chorus intensity and bandwidth. We find that a temperature anisotropy (T⊥/T∥ ~ 1.3) can account for linear spatiotemporal growth rate of whistler mode waves, which provides a majority of the observed frequency‐integrated power. At the highest frequencies, intense, nonlinear, frequency‐drifting structures (drift rates ~ 200 Hz/s) are observed a few degrees away from the equator and can account for a significant fraction of the total power. Chorus emission at higher frequencies is distinct from lower frequency whistler mode emission and is sometimes correlated with simultaneously observed low‐frequency electromagnetic ion cyclotron waves. These electromagnetic ion cyclotron waves appear to modulate a slow frequency drift (~15 Hz/s) which develops into nonlinear growth with much larger frequency drift associated only with the higher‐frequency chorus.
Solar cycle dependence of High‐Intensity Long‐Duration Continuous AE Activity (HILDCAA) events, relativistic electron predictors?
Authors: Hajra R. , Echer E. , Tsurutani B. T. , Gonzalez W. D.
Published: August 2013

High‐Intensity, Long‐Duration, Continuous AE Activity (HILDCAA) events are studied using long‐term geomagnetic and solar wind/interplanetary databases. We use the strict definition of a HILDCAA event, that it occurs outside of the main phase of a magnetic storm, the peak AE is >1000 nT, and the duration is at least 2 days long. One hundred thirty‐three events have been identified from the AE indices in the 1975 to 2011 interval, a ~3½ solar cycle span. Of the 133 events, 99 had simultaneous interplanetary data available. The overwhelmed majority (94%) of these latter cases were associated with high‐speed solar wind stream (HSS) events. The remaining 6% of the cases occurred after the passage of interplanetary coronal mass ejections (ICMEs). The HSS‐related events were typically associated with large interplanetary magnetic field (IMF) Bz variances. The ICME‐related events were characterized by steady southward Bz intervals or low‐frequency fluctuations, both of which we view as possible different interplanetary phenomena. HILDCAA events have been found to have their largest occurrence frequency in the solar cycle descending phase (~6.8/year) with the second largest at solar minimum (~3.5/year). The occurrence frequencies were considerably lower in the ascending phase (~2.5/year) and at solar maximum (~2.2/year). Thus, HILDCAAs can occur during all phases of the solar cycle, with the descending phase approximately three times more likely to have an event than at solar maximum and the ascending phase. The HILDCAA events that occurred in the declining phase and at solar minimum were >20% longer in duration than those in the ascending phase and solar maximum, respectively. The events during the recent solar and geomagnetic minima, 2007–2009, were, on the average, ~17% and 14% weaker in peak AE than the events during the previous two minima of 1995–1997 and 1985–1987, respectively. The recent minimum events were ~35% and 41% shorter in durations, respectively, than the events during those previous minima. The yearly occurrence of the events exhibited statistically significant correlation (>0.70) with yearly average speed and number of HSSs. No seasonal dependence of HILDCAA was noted.