bluuebunny/crossref_metadata_2025 huggingface dataset:
Culture under low physiological oxygen conditions improves the stemness and quality of induced pluripotent stem cells
Authors: Guo Chao‐Wan , Kawakatsu Miho , Idemitsu Marie , Urata Yoshishige , Goto Shinji , Ono Yusuke , Hamano Kimikazu , Li Tao‐Sheng
Published: April 2013

The ex vivo expansion of stem cells under low physiological oxygen (O2) conditions has been demonstrated to improve the stemness and genomic stability of the cells. We investigated whether low‐oxygen culture would be beneficial for the culture of induced pluripotent stem (iPS) cells. Two human iPS cell lines (201B7 and 253G1) were used for the experiments. Cells expanded from a single colony of each cell line were initiated for culture in 2.5% O2, 5% O2, or 20% O2 and maintained for 2 months in parallel. The levels of intracellular and mitochondrial reactive oxygen species did not differ between the cells cultured under different conditions. More colonies of uniformly smaller size were observed at 2.5% and 5% O2 than at 20% O2. All of these iPS colonies that expanded under the various oxygen conditions stained positively for Oct3/4, Nanog, SSEA‐4, and ALP. However, Western blot analysis showed that the iPS cells cultured at 2.5% and 5% O2 expressed significantly more Nanog but less 53BP1 than those cultured at 20% O2. Data from an array CGH showed no significant chromosomal abnormalities, although some genes involved in cellular and metabolic processes were amplified in the low oxygen culture, particularly at 2.5% O2. Our data suggest that low physiological oxygen culture could improve the stemness and quality of iPS cells, a result that might be associated with the amplification of genes involved in metabolic and cellular processes. Long‐term culture will be necessary to confirm whether low physiological oxygen levels also improve genomic stability. J. Cell. Physiol. 228: 2159–2166, 2013. © 2013 Wiley Periodicals, Inc.
Regulation of the delta and alpha epithelial sodium channel (ENaC) by ubiquitination and Nedd8
Authors: Ly Kevin , McIntosh C. Joy , Biasio Wolfgang , Liu Yongfeng , Ke Ying , Olson Diane R. , Miller John H. , Page Rachel , Snyder Peter M. , McDonald Fiona J.
Published: April 2013

The δ epithelial sodium channel (δENaC) is a proton‐activated, sodium‐selective, amiloride‐sensitive ion channel in the ENaC/degenerin family of ion channels involved in blood pressure regulation and mechanosensation. Other ENaC family members are subject to ubiquitin modification leading to internalization from the cell surface, and degradation of the channel. Here, we show that δENaC is also modified by ubiquitin on three intracellular lysine residues. Absence of these lysines abolished ubiquitin modification of δENaC and increased cell surface levels of δENaC. Although the HECT‐domain ubiquitin ligase Nedd4‐2 reduced amiloride‐sensitive current generated by δβγENaC‐containing channels, δENaC does not contain a binding site for Nedd4‐2; therefore, this effect is probably mediated by the βγENaC subunits. Nedd8, a ubiquitin‐like protein that regulates RING‐domain E3 ubiquitin ligases, promoted δENaC ubiquitination, decreased both the intracellular and cell surface δENaC populations, and decreased δβγENaC amiloride‐sensitive short circuit current (Isc‐amiloride) in a mammalian epithelium. Nedd8 also promoted α− and γENaC ubiquitination, decreased the cell surface pools, and decreased αβγENaC Isc‐amiloride. Conversely, XIAP, a single subunit RING E3 ligase, decreased ubiquitinated δENaC, increased the δENaC cell surface pool and increased δβγENaC Isc‐amiloride. Therefore δ− and α − βγENaC channel function may be influenced by RING‐domain E3 ubiquitin ligases. J. Cell. Physiol. 228: 2190–2201, 2013. © 2013 Wiley Periodicals, Inc.
Markers of cochlear inflammation using MRI
Authors: Floc'h Johann Le , Tan Winston , Telang Ravindra S. , Vlajkovic Srdjan M. , Nuttall Alfred , Rooney William D. , Pontré Beau , Thorne Peter R.
Published: April 2013

Purpose

To quantify spatial and temporal inflammation‐induced changes in vascular permeability and macrophage infiltration in guinea‐pig (GP) cochlea using MRI.

Materials and Methods

GPs were injected with lipopolysaccharide (LPS) to induce cochlear inflammation. One group was injected with a gadolinium based contrast agent (GBCA) and dynamic contrast enhanced (DCE)‐MRI was performed at 4, 7, and 10 days after LPS treatment. A two‐compartment pharmacokinetic model was used to determine the apparent rate constant of GBCA extravasation (Ktrans). A second group was injected with ultrasmall superparamagnetic iron oxide particles (USPIOs) and studied at 2, 3, and 7 days after LPS treatment to detect tissue USPIO uptake and correlate with histology. For both groups, control GPs were scanned similarly.

Results

The signal enhancement increased substantially and more rapidly at day 4 in LPS‐treated than in control cochlea shortly following GBCA injection. Ktrans of LPS‐treated cochlea was maximum on day 4 at 0.0218 ± 0.0032 min−1 and then decreased to control level at 0.0036 ± 0.0004 min−1 by day 10. In the second group, the relative signal intensity and T2 in cochlear perilymphatic spaces on day 2 decreased, on average, by 54% and 45%, respectively, compared with baseline and then remained under control levels by day 7. This suggests the infiltration of inflammatory cells, although unconfirmed by histology.

Conclusion

This provides the first measurement of cochlear vascular permeability using MRI and a quantitative evaluation of the development of cochlear inflammation. MRI holds considerable potential for the assessment of disease processes such as clinical diagnosis of conditions such as labyrinthitis. J. Magn. Reson. Imaging 2014;39:150–161. © 2013 Wiley Periodicals, Inc.
MR elastography for noninvasive assessment of hepatic fibrosis: Reproducibility of the examination and reproducibility and repeatability of the liver stiffness value measurement
Authors: Lee Ye ji , Lee Jeong Min , Lee Jeong Eun , Lee Kyung Bun , Lee Eun Sun , Yoon Jeong‐Hee , Yu Mi Hye , Baek Jee Hyun , Shin Cheong Il , Han Joon Koo , Choi Byung Ihn
Published: April 2013

Purpose

To determine the reproducibility of MR elastography (MRE) and the reproducibility and repeatability of the stiffness measurement of MRE in the staging of liver fibrosis.

Materials and Methods

Ninety‐four patients, who underwent liver MRE, were included in this study. The patients were classified into group 1 (n = 47) and group 2 (n = 47) according to our knowledge of their histologic hepatic fibrosis (HF) stage. To analyze the reproducibility of MRE, the group 1 patients underwent MRE twice. In addition, to evaluate the repeatability and reproducibility of the stiffness measurement of MRE, a single observer measured the stiffness values of the second MREs in group 1 twice, and two observers independently measured the stiffness values of MRE in group 2. A 95% Bland‐Altman limits of agreement and intraclass correlation coefficients (ICCs) were used to evaluate the reproducibility and repeatability of MRE.

Results

In group I, there was no significant difference in the mean liver stiffness values of the first and second MRE examinations, i.e., 3.45 ± 0.25 kPa vs. 3.35 ± 0.23 kPa (p = 0.22). The reproducibility of the MRE examination and the reproducibility and repeatability of the stiffness measurement were high, i.e., the ICCs of each parameter were 0.945, 0.827, and 0.963, respectively, and the 95% limits of agreement were 25.3%, 35.35%, and 18.0%, respectively.

Conclusion

MRE is a promising tool for evaluating HF and has high reproducibility of the examination as well as reproducibility and repeatability of the stiffness measurements. J. Magn. Reson. Imaging 2014;39:326–331. © 2013 Wiley Periodicals, Inc.
MRI for acute chest pain: Current state of the Art
Authors: François Christopher J. , Hartung Michael P. , Reeder Scott B. , Nagle Scott K. , Schiebler Mark L.
Published: April 2013

This article reviews the magnetic resonance imaging (MRI) and angiography (MRA) techniques, imaging findings, and evidence for evaluating patients with acute chest pain due to acute pulmonary embolus (PE), aortic dissection (AD), and myocardial infarction (MI). When computed tomographic angiography (CTA) is contraindicated, MRI and MRA are important alternative imaging modalities for diagnosis and management of patients with acute PE, AD, and MI. Familiarity with the techniques, imaging findings, and evidence is critical to safely and appropriately managing patients presenting with acute chest pain. J. Magn. Reson. Imaging 2013;37:1290–1300. © 2013 Wiley Periodicals, Inc.
UFLC–MS/MS method for simultaneous determination of six lignans of Schisandra chinensis (Turcz.) Baill. in normal and insomniac rats brain microdialysates and homogenate samples: towards an in‐depth study for its sedative‐hypnotic activity
Authors: Wei Binbin , Li Qing , Fan Ronghua , Su Dan , Ou Xiuli , Chen Kelin , Chen Xiaohui , Jia Ying , Bi Kaishun
Published: April 2013

Schisandra chinensis (Turcz.) Baill., a traditional Chinese medicine, has been clinically used for the treatment of insomnia for centuries. The insomnia mechanism and the possible active ingredients of S. chinensis remain largely unknown. The objective of this study was to develop a method to detect its components which could pass through the blood brain barrier (BBB) by determining the brain microdialysate and brain tissue homogenate samples and then obtain the pharmacokinetic profile in brain for comprehensive understanding of its hypnotic clinical efficacy. Therefore, an efficient, sensitive and selective ultra fast liquid chromatography/tandem mass spectrometry method for the simultaneous determination of six sedative and hypnotic lignans (schisandrin, schisandrol B, schisantherin A, deoxyshisandrin, γ‐schisandrin and gomisin N) of Schisandra chinensis (Turcz.) Baill. in rat brain tissue homogenate and brain microdialysates has been developed and validated. The analysis was performed on a Shim‐pack XR‐ODS column (75 mm × 3.0 mm, 2.2 µm) using gradient elution with the mobile phase consisting of acetonitrile and 0.1% formic acid water. The method was validated in brain homogenate and microdialysate samples, which all showed good linearity over a wide concentration range (r2 > 0.99), and the obtained lower limit of quantification was 0.1 ng · ml−1 for the analytes in brain microdialysate samples. The intra‐ and inter‐day assay variability was less than 15% for all analytes. The study proved the six lignans, as sedative and hypnotic ingredients, could pass through the BBB with brain targeting, distributed mainly in the hypothalamus and possessed complete pharmacokinetics process in brain. The results also indicated that significant difference in pharmacokinetic parameters of the analytes was observed between two groups, while absorptions of these analytes in insomniac group were significantly better than those in normal group. Copyright © 2013 John Wiley & Sons, Ltd.
From the mobile proton to wandering hydride ion: mechanistic aspects of gas‐phase ion chemistry
Authors: Bouchoux Guy
Published: April 2013

Structural characterization of molecular species by mass spectrometry supposes the knowledge of the type of ions generated and the mechanism by which they dissociate. In this context, a need for a rationalization of electrospray ionization(+)(−) mass spectra of small molecules has been recently expressed. Similarly, at the other end of the mass scale, efforts are currently made to interpret the major fragmentation processes of protonated and deprotonated peptides and their reduced forms produced in electron capture or electron transfer experiments.

Most fragmentation processes of molecular and pseudo‐molecular ions produced in the ion source of a mass spectrometer may be described by a combination of several key mechanistic steps: simple bond dissociation, formation of ion‐neutral complex intermediates, hydrogen atom, hydride ion or proton migrations and nucleophilic attack. Selected crucial aspects of these elementary reactions, occurring inside positively charged ions, will be recalled and illustrated by examples taken in recent mass spectrometry literature. Emphasis will be given on the protonation process and its consequence in terms of structure and energetic. Copyright © 2013 John Wiley & Sons, Ltd.
Specificity of squamous cell carcinoma antigen (SCCA)‐IgM detection in patients with HCV infection and rheumatoid factor seropositivity
Authors: Biasiolo Alessandra , Tono Natascia , Zaninotto Martina , Merkel Carlo , Fassina Giorgio , Plebani Mario , Gatta Angelo , Pontisso Patrizia
Published: April 2013

IgM antibodies bound to different cancer antigens have shown recently a higher diagnostic value, compared with the corresponding free molecule, giving rise to a new family of biomarkers. High or increasing levels of Squamous Cell Carcinoma Antigen (SCCA)‐IgM immune complexes were associated with more advanced liver disease and increased risk of development of HCC. Rheumatoid factor (RF) represents a long‐standing problem of interference for immunometric assays. The aim of the present study was to examine the specificity of SCCA‐IgM in relation to the presence of RF reactivity in patients infected with hepatitis C virus (HCV). Sera of 73 patients with cirrhosis, infected with HCV, (mean age ± SD: 66 ± 13 years; M/F: 45/28), including 21 patients with HCC, were studied. SCCA‐IgM immune complexes levels were measured by a commercial ELISA. To evaluate the possible interfering effect of RF, the standard calibrator, positive for SCCA‐IgM, was spiked with serial dilutions of a RF positive or negative serum. SCCA‐IgM immune complexes were positive in 35 out of 73 (48%) patients, while RF activity was found in 10 out of 73 (14%) patients. Patients with cirrhosis with RF activity had significantly higher levels of SCCA‐IgM, compared to RF negative cases; however, no significant correlation between SCCA‐IgM and RF values was observed. In samples created artificially the same results in terms of reactivity for SCCA‐IgM were obtained, regardless of the presence of RF activity. These findings support the lack of correlation between the two parameters found in sera of patients infected with HCV. J. Med. Virol. 85: 1005–1008, 2013. © 2013 Wiley Periodicals, Inc.
Seroprevalence of neutralizing antibodies to human adenoviruses type‐5 and type‐26 and chimpanzee adenovirus type‐68 in healthy Chinese adults
Authors: Zhang Shujun , Huang Wenxiang , Zhou Xiangyang , Zhao Qiquan , Wang Qun , Jia Bei
Published: April 2013

Replication‐defective adenoviruses have been utilized as candidate vaccine vectors. However, clinical application of the best‐studied human adenovirus type‐5 (AdHu5) is limited by the high prevalence of preexisting neutralizing antibodies resulting from natural infection. Therefore, rare adenovirus serotypes, such as human adenovirus type‐26 (AdHu26) and chimpanzee adenovirus type‐68 (AdC68), have been employed as substitutes for AdHu5. However, few studies have described the epidemiology of pre‐existing immunity to these adenoviruses in China. Thus, 1,154 participants from six regions in China were examined to assess the presence of neutralizing antibodies against AdHu5, AdHu26, and AdC68. The seroprevalence rates of neutralizing antibodies were as follows: AdHu5, 73.1% (844/1,154) (95% confidence interval: 70.5–75.6%); AdHu26, 35.3% (407/1,154) (95% confidence interval: 32.6–38.1%); and AdC68, 12.7% (147/1,154) (95% confidence interval: 10.9–14.8%), respectively. The most frequently detected and highest titer antibodies were specific for AdHu5. The results indicate that AdHu26 and AdC68 serve as more suitable vaccine vectors than AdHu5. J. Med. Virol. 85: 1077–1084, 2013. © 2013 Wiley Periodicals, Inc.
Low‐level viremia is associated with non‐B subtypes in patients infected with HIV with virological success following HAART introduction
Authors: Saison Julien , Tardy Jean‐Claude , Scholtes Caroline , Icard Vinca , Trabaud Mary‐Anne , Perpoint Thomas , Chidiac Christian , Ecochard René , André Patrice , Ferry Tristan ,   on behalf of the Lyon HIV Cohort Study
Published: April 2013

This prospective study aimed to determine factors associated with detection of very low‐level viremia in patients infected with HIV‐1 with virological success following HAART introduction. Fifty‐seven patients, mostly (n = 51, 89%) treated with a protease inhibitor‐based regimen, were included and followed for 2 years. Viral loads were monitored by Abbott m2000 RealTime HIV‐1. Patients were classified as (i) HIV‐RNA‐negative if viral loads remained strictly undetectable (0 copies/ml), or (ii) HIV‐RNA‐positive if at least one HIV‐1 RNA could be detected in 1–49 copies/ml during follow‐up. At month 24, 44 patients (77%) were in the HIV‐RNA‐positive group, whereas 13 (23%) remained without very low‐level viremia. Univariate analysis, Kaplan–Meier curves and the Cox proportional hazard model revealed that B subtype was the only predictor of belonging to the HIV‐RNA‐negative group (HR 3.98; 95% CI 1.08–14.7). This association needs to be confirmed. Further study of the reservoir and the mechanisms of viral latency according to HIV‐subtype will also be necessary to develop new therapeutic strategies and eradicate HIV infection. J. Med. Virol. 85: 953–958, 2013. © 2013 Wiley Periodicals, Inc.
Frequent occurrence of parvovirus B19 DNAemia in the first year after kidney transplantation
Authors: Porignaux Roseline , Vuiblet Vincent , Barbe Coralie , Nguyen Yohan , Lavaud Sylvie , Toupance Olivier , Andréoletti Laurent , Rieu Philippe , Lévêque Nicolas
Published: April 2013

Described for the first time in 1986, Parvovirus B19 (B19V) infection in kidney transplant recipients remains little‐known and probably underestimated. The aims of this study were to establish B19V infection frequency during the first year after kidney transplant and to determine predisposing factors and manifestations of the infection in renal transplant recipients. Sixty consecutive adult patients, transplanted less than a year before, were included in this study. B19V and other opportunistic viral infections were detected retrospectively in plasma samples collected every 15 days during the first 3 months and every month from 3 months to 1 year following the kidney transplant. Demographic characteristics, immunosuppressive treatment and biological findings were recorded on each sampling date. Six patients (10%) presented B19V viremia, while eight CMV (13.3%), seven EBV (11.7%), five HHV‐6 (8.3%), five BKV (8.3%), and two adenovirus (3.3%) infections were detected. The mean value of B19V viral load was 149 UI/ml. B19V infections were either reactivation or reinfection due to genotype two in five cases, while one case of primary infection with genotype 1 was observed. Neither risk factors nor biological consequences of B19V infection have been identified. These results rank B19V third among opportunistic viral infections occurring during the first year after a kidney transplant. With regard to this high incidence, and even if the risk factors and biological consequences of the infection should be assessed in larger studies, the question of systematic screening and follow‐up of B19V infection in kidney transplant recipients is relevant. J. Med. Virol. 85: 1115–1121, 2013. © 2013 Wiley Periodicals, Inc.
Monitoring of KI and WU polyomaviruses in hematopoietic stem cell transplant patients
Authors: Porrovecchio Rosa , Babakir‐Mina Muhammed , Rapanotti Maria Cristina , Arcese William , Perno Carlo Federico , Ciotti Marco
Published: April 2013

Primary infection with KIPyV and WUPyV polyomaviruses occurs early in childhood followed by lifelong persistence in the body. Polyomavirus reactivation can occur in the presence of impaired immunity as in hematological malignancies or during immunosuppresssion induced by medications. In this study, reactivation of KIPyV and WUPyV was monitored by conventional PCR in plasma samples of 26 stem cell transplant patients and in 26 related bone marrow donors. Plasma samples from transplant patients were collected immediately after the end of conditioning regimen and up to 270 days after transplant. All plasma samples from transplant patients were negative for KIPyV and WUPyV DNA. Instead, KIPyV DNA was detected in two bone marrow donors. There was no evidence of KIPyV transmission from the donor to the recipient. The data suggest that detection of KIPyV in plasma is sporadic and that KPIyV and WUPyV do not affect the post‐transplant clinical course. However, further studies on a larger sample size and more sensitive PCR methods are needed to confirm these observations. J. Med. Virol. 85: 1122–1124, 2013. © 2013 Wiley Periodicals, Inc.
Vibrational spectroscopy investigation of swelling phenomena in cyclodextrin nanosponges
Authors: Castiglione Franca , Crupi Vincenza , Majolino Domenico , Mele Andrea , Rossi Barbara , Trotta Francesco , Venuti Valentina
Published: April 2013

The swelling behaviour of β‐cyclodextrin nanosponges, a new class of polymers obtained by reacting β‐cyclodextrin with pyromellitic dianhydride, has been here investigated by the analysis of the vibrational dynamics performed by using Fourier‐transform infrared spectroscopy in Attenuated Total Reflectance geometry and Raman scattering. The measurements have been carried out at different hydration levels and in the temperature range 250 K–310 K. The decomposition and assignment of the spectral components of the O–H stretching band have been discussed in terms of water molecules engaged in different hydrogen bonding networks, allowing us to recognize three different ‘types’ of water, namely ‘bonded’, ‘intermediate'and ‘free’. By following this approach, a detailed picture of the connectivity pattern of water molecules inside the polymeric matrix is achieved. The analysis of HOH bending vibrational band gives further information perfectly consistent with the results obtained from the analysis of the O–H stretching spectral region. Copyright © 2013 John Wiley & Sons, Ltd.
Use of the Trifunctional Cyclic Initiator, DEKTP, as the Radical Initiator in the Modification of Poly(propylene) in the Presence of Different Branching/Crosslinking Co‐Agents
Authors: García L. , Morales G. , Avalos B F. , Acuña P.
Published: April 2013

Homopolypropylene was modified in the molten state using a new cyclic multifunctional peroxide as the initiator, the Diethyl Ketone Triperoxide (DEKTP), in the presence of different branching/crosslinking co‐agents: Trimethylolpropane Triacrylate (TM), Trimethylolpropane Triacrylate Propoxylate (TMPP), Pentaerythritol Tetraacrylate (PETA) and N′N′‐1,3‐Phenylene Dimaleimida (FDM). Experiments were carried out in an internal mixer at 180 °C, using two different concentrations of co‐agent/initiator; [0.250/0.025] and [0.50/0.05], molar rate = [co‐agent]/[initiator] constant equal to 10. The modified PP′s were evaluated by GPC, FTIR, DSC, WAXD, and MOP. Torque and MFI were also evaluated. The results showed the presence of branches in the backbone of PP when it was modified with TM and PETA.
Aromatic Polyamides Density from Molecular Dynamics Simulation
Authors: Santiago García José Luis , Bastarrachea María Isabel Loría , de Jesús Aguilar Vega Manuel
Published: April 2013

Molecular dynamics simulations have been performed on seven aromatic polyamides to understand the structure‐property relationships on their densities. The aromatic polyamides studied in this work are based on poly(hexafluoroisopropylidene) isophthalamide, HFAISO. The aim of this research is to investigate the effect of the side groups attached to the diacid monomer on the density of the aromatic polyamides. Densities were obtained via NVT and NPT molecular dynamics simulation using the COMPASS forcefield. Reliability and accuracy of the simulations were compared with the experimental density data from HFAISO and HFATERT aromatic polyamides, which are in good agreement.
Cyclometalated Ruthenium(II) Complex as a Versatile Catalyst for Living/Controlled Radical Polymerization of Hydrophobic and Hydrophilic Monomers
Authors: Alfredo Nelson Vargas , Aguilar‐Lugo Carla , Gonzalez Ortencia Diaz , Le Lagadec Ronan , Alexandrova Larissa
Published: April 2013

Cyclometalated complex, cis‐[Ru(phpy)(phen)(MeCN)2]PF6, bearing strongly bound ligands (phpy = 2‐phenylpyridine, phen = 1, 10‐ phenantroline) and relatively labile (MeCN) ligands, in conjunction with ethyl 2‐bromoisobutyrate (EBiB), was used for radical polymerization of three hydrophobic, styrene (St), methyl methacrylate (MMA), n‐butyl acrylate (BA), and one hydrophilic, 2‐hydroxyethyl methacrylate (HEMA), monomers. The polymerizations were fast and reasonably controlled; the molecular weights increased with conversion and were close to the calculated values. The best control was achieved in polymerization of St. The complex was able to mediate this polymerization with acceptable rate and level of control even at a monomer/catalyst ratio of 2000. The living character of the polymerizations was confirmed by chain extension experiments; the degree of polymer “livingness” was less for PMMA than for PSt. Because of ionic nature, the complex was well soluble in MeOH and thus catalyzed polymerization of HEMA under homogeneous conditions at 50 °C.
Anionic Synthesis of α‐Functionalized Polymers by Combination of 1,1‐Diphenylethylene and Hydrosilation Chemistry
Authors: Quirk Roderic P. , Sahoo Sujata
Published: April 2013

A new general anionic functionalization method (GFM) for preparing α‐chain‐end functionalized polymers utilizes the initiator formed from sec‐butyllithium and dimethyl[4‐(1‐phenylvinyl)‐phenyl]silane (DPESiH) followed by hydrosilation with substituted alkenes. α‐(4‐dimethylsilyl hydride)phenyl‐functionalized polystyrene and poly(methyl methacrylate) were synthesized in quantitative yield by living anionic polymerization. These α‐silyl hydride‐functionalized polymers were further functionalized by reaction with tridecafluorooctene in the present of Karstedt's hydrosilation catalyst. These tridecafluorooctane‐functionalized polymers were characterized by SEC, FTIR, 1H‐, 13C‐ and 19F‐NMR spectroscopy.
Nanoscale versus Microscale Gelation for Crosslinked Polyurethanes
Authors: Wang Chenyu , Zhang Wei , Wynne Kenneth J.
Published: April 2013

In analyzing morphology of modified surfaces it is important to distinguish between features attributable to the matrix and those for the modifier. This study focused on an examination of the surface morphology of closely related linear and network polyurethanes intended for use as bulk coating constituents. A process dependent morphology is found for the crosslinked polyurethane matrix. Microscale gelation was found when reagents were added simultaneously, while nanoscale gelation occurs when the cross‐linker is added last. Furthermore, the coating formed by sequential addition had 50% less extractables. Future work on modified networks will focus on the matrix with nanoscale gelation as it presents a “cleaner” canvas for surface modification.
What Makes a Blockbuster Video Game? An Empirical Analysis of US Sales Data
Authors: Cox Joe
Published: April 2013

This study uses a unique data set of individual video game titles to estimate the effect of an exhaustive set of observable characteristics on the likelihood of a video game becoming a blockbuster title. Due to the long‐tailed distribution of the sales data, both ordinary least squares and logistic regression models are estimated. The results consistently show that blockbuster video games are more likely to be released by one of the major publishers for popular hardware platforms. Results also show that games of higher quality are significantly more likely to sell a greater number of units than those of a lower quality. Copyright © 2013 John Wiley & Sons, Ltd.
Preemptive Bidding in Takeover Auctions: An Experimental Study
Authors: Khoroshilov Yuri , Dodonova Anna
Published: April 2013

This paper presents the results of an experimental study on jump bidding in takeover auctions with entry costs. It provides support for signaling hypothesis behind jump bidding and analyzes how the size of the entry costs affects the bidders' behavior and their expected profits. It also shows that jump bidding allows the reallocation of the surplus from the seller to the first bidder but has little effect on the social surplus and the profits of the second bidder. Copyright © 2013 John Wiley & Sons, Ltd.
Neuronal vulnerability, pathogenesis, and Parkinson's disease
Authors: Sulzer David , Surmeier D. James
Published: April 2013

Although there have been significant advances, pathogenesis in Parkinson's disease (PD) is still poorly understood. Potential clues about pathogenesis that have not been systematically pursued are suggested by the restricted pattern of neuronal pathology in the disease. In addition to dopaminergic neurons in the substantia nigra pars compacta (SNc), a significant number of other central and peripheral neuronal populations exhibit Lewy pathology (LP), phenotypic dysregulation, or frank degeneration in PD patients. Drawing on this literature, there appears to be a small number of risk factors contributing to vulnerability. These include autonomous activity, broad action potentials, low intrinsic calcium buffering capacity, poorly myelinated long highly branched axons and terminal fields, and use of a catecholamine neurotransmitter, often with the catecholamine‐derived neuromelanin pigment. Of these phenotypic traits, only the physiological ones appear to provide a reachable therapeutic target at present. © 2013 Movement Disorder Society
A novel nonsense mutation in keratin 10 causes a familial case of recessive epidermolytic ichthyosis
Authors: Gutierrez Jeydith A. , Hannoush Zeina C. , Vargas Luis G. , Momany Allison , Garcia Carmen C. , Murray Jeffrey C. , Dunnwald Martine
Published: April 2013

Epidermolytic ichthyosis (EI) is a rare skin disorder characterized by generalized erythroderma and cutaneous blistering at birth, which is substituted by hyperkeratosis later in life. It is caused by autosomal dominant mutations in highly conserved regions of KRT1 and KRT10. To date, only four mutations with autosomal recessive inheritance of EI have been described in consanguineous families. All of them affect the 2B domain of KRT10. In the present study, we describe four patients with EI (including one lethal case) born from unaffected parents in a consanguineous family of a native Venezuelan community. The objective of this study was to characterize the clinical, genetic, and morphological aspects of the disease in this family, as well as understand its functional implications. Genomic DNA was sequenced for KRT10 and KRT1. Immunofluoresence for keratin expression was performed on cutaneous biopsies. After examination of cutaneous biopsies histology, our results showed hyperkeratosis and acantholysis with an expanded granular layer. Sequencing of KRT10 demonstrated a nonsense mutation (p.Tyr282Ter.) corresponding to the 1B domain of the protein in patients and a heterozygous pattern in other family members, resulting in complete absence of K10. The loss of K10 was compensated by upregulation of K14 and K17. In conclusion, this novel mutation in KRT10 is the first recessive genetic variation that is not located in the so called “hot spot” for recessive EI, suggesting that other areas of the gene are also susceptible for such mutations.
Clinical Adjusted Photodynamic Therapy
Authors: Ziolkowska Maria , Carsten Carsten M. , Mueller Ute , Urban Peter , Berlien H.‐Peter
Published: April 2013

Lasers are currently used in diagnostics, for example in metabolic monitoring (fluorescence diagnosis, laser Doppler) and optical imaging (laser scanning microscopy, optical coherence tomography, infrared diaphanoscopy). One main research focus remains therapeutic applications — on one hand using lasers as a surgical instrument, on the other as a central, independent therapy method. Historically, the traditional indication for photodynamic therapy (PDT) has been malignant tumors, but experience of photodynamic therapy in this field and understanding of the biochemical metabolic processes involved, has expanded the use of this therapeutic principle to benign diseases. But even as developments in surgical applications (for example, the development of “laser scalpels”) are recorded in the last few years advancements have also been made in other areas, such as virtual endoscopy in MRI.
Acceleration Profile of a Flat Flyer Driven by Detonation Isentrope
Authors: Lim Seokbin
Published: April 2013

In the design of explosive devices, understanding of the behavior of explosively propelled matter is one of the important steps to optimize the performance of the device. In a typical flat, metallic flyer and explosives charge system, the flyer reaches its maximum velocity after a certain degree of expansion of the detonation gas. During this expansion, the flyer is deformed in an arced‐shape by the incoming rarefaction from nearby surfaces. In this work, an acceleration/deformation profile of an explosively propelled flat, metallic plate was studied based on the isentropic expansion of detonation gas and subsequent rarefaction intrusion to the center of the flyer. In order to properly describe the arced deformation of the flyer, a rather simplified new term of the pressure release ratio behind the flyer η is introduced based on the expansion of the detonation isentrope behind the flyer. A theoretical model was built to predict the behavior of an explosively driven flyer and the rarefaction intrusion into the center of the explosives charge. The results are compared to a hydrocode simulation and exhibit favorable agreement in a limited application.
Predictive 3D modelling of the interactions of pyrethroids with the voltage‐gated sodium channels of ticks and mites
Authors: O'Reilly Andrias O , Williamson Martin S , González‐Cabrera Joel , Turberg Andreas , Field Linda M , Wallace B A , Davies T G Emyr
Published: April 2013

BACKGROUND

The pyrethroid insecticides are a very successful group of compounds that target invertebrate voltage‐gated sodium channels and are widely used in the control of insects, ticks and mites. It is well established that some pyrethroids are good insecticides whereas others are more effective as acaricides. This species specificity is advantageous for controlling particular pest(s) in the presence of another non‐target invertebrate, for example controlling the Varroa mite in honeybee colonies.

RESULTS

We applied in silico techniques to compare the voltage‐gated sodium channels of insects versus ticks and mites and their interactions with a range of pyrethroids and DDT analogues. We identified a single amino acid difference within the pyrethroid binding pocket of ticks/mites that may have significant impact on the effectiveness of pyrethroids as acaricides. Other individual amino acid differences within the binding pocket in distinct tick and mite species may provide a basis for future acaricidal selectivity.

CONCLUSIONS

Three–dimensional modelling of the pyrethroid/DDT receptor site has led to a new hypothesis to explain the preferential binding of acaricidal pyrethroids to the sodium channels of ticks/mites. This is important for understanding pyrethroid selectivity and the potential effects of mutations that can give rise to resistance to pyrethroids in commercially‐important pest species. © 2013 Society of Chemical Industry
Sensitivity of Phakopsora pachyrhizi towards quinone‐outside‐inhibitors and demethylation‐inhibitors, and corresponding resistance mechanisms
Authors: Schmitz Helena K , Medeiros Carlos‐Antonio , Craig Ian R , Stammler Gerd
Published: April 2013

BACKGROUND

Since the invasion of Phakopsora pachyrhizi (Syd. & P. Syd.) in Brazil, there have been detrimental yield losses of soybeans [Glycine max (L.) Merr.]. Disease management is mainly based on fungicide treatment. The sensitivity of single P. pachyhrizi isolates towards different demethylation‐inhibitors (DMIs) and quinone‐outside‐inhibitors (QoI) was surveyed and the corresponding resistance mechanisms were analysed.

RESULTS

The QoI‐response remained stable, while a loss of sensitivity towards DMIs occurred. Molecular analyses of cytochrome b showed an intron after codon 143 which is reported to prevent the development of a G143A mutation. Analysis of cyp51 revealed that point mutations and overexpression are involved in the sensitivity reduction towards DMIs. Of the detected mutations, Y131F and Y131H, respectively, and K142R are likely homologous to mutations found in other pathogens. As suggested by modelling studies, these three mutations as well as additional mutations F120L, I145F and I475T correlate to increased effective doses of 50%, ED50‐values, towards all tested DMIs. Furthermore, a constitutive up‐regulation of the cyp51‐gene up to ten‐fold was noticed in some of the DMI‐adapted isolates, while all sensitive isolates responded as the wild type.

CONCLUSION

The G143A mutation is thought to result in significant as well as stable resistance factors towards QoIs, while other mutations play only a minor role. Since G143A development is prevented in Phakopsora pachyhrizi, a stable control of soybean rust with QoIs in future is rather likely. In contrast, a shifting in sensitivity towards DMIs has been observed, which is due to multiple independent mechanisms. © 2013 Society of Chemical Industry
Interface structural stability of Zr on the AIN(0001) surface: An ab‐initio study
Authors: Escorcia‐Salas Gene E. , Rivera‐Julio Jagger , López‐Pérez William , González‐Hernández Rafael , Sierra‐Ortega José
Published: April 2013

Ab‐initio density functional theory calculations are carried out to investigate the role of zirconium (Zr) impurity atoms during AlN(0001) surface growth. Adsorption and diffusion of Zr atoms on AlN(0001)‐2 × 2 surface is examined and it is shown that Zr atoms preferentially adsorb at the T4 sites at low and high coverage (from 1/4 up to 1 monolayer). We found that the Zr adatom diffusion energy barrier between the T4 and H3 sites is around ∼0.4 eV, which is an indication of a significant Zr adatom diffusion on this surface. In addition, calculating the relative surface energy of several configurations and various Zr concentrations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the Zr and Al chemical potentials. Based on these results, we find that incorporation of Zr adatoms in the Al‐substitutional site is energetically more favorable compared with the adsorption on the top layers. This effect leads to the formation of a non‐reactive interfacial ZrN(111) layer on the AlN(0001) surface, which can offer a good interfacial combination between AlN substrate and other metal contacts, i.e. zirconium.
Monitoring phosphodiesterase‐4 inhibitors using liquid chromatography/(tandem) mass spectrometry in sports drug testing
Authors: Thevis Mario , Krug Oliver , Schänzer Wilhelm
Published: April 2013

RATIONALE

The recent discovery of resveratrol's capability to inhibit cAMP‐specific phosphodiesterases (PDEs) and, as a consequence, to enhance particularly the activity of Sirt1 in animal models has reinforced the interest of preventive doping research organizations, especially in PDE4 inhibitors. Among these, the archetypical PDE4‐inhibitor rolipram significantly increased the number of mitochondria in laboratory rodents, which further demonstrated a performance increase in a treadmill‐test (time‐to‐exhaustion) of approximately 40%. Besides rolipram, a variety of new PDE4‐inhibiting substances including cilomilast, roflumilast, and numerous additional new drug entities were described, with roflumilast being the first‐in‐class having received clinical approval for the treatment of chronic obstructive pulmonary disease (COPD). Due to the availability of these substances, and the fact that a misuse of such compounds in sport cannot be excluded, it deems relevant to probe for the prevalence of these compounds in sports drug testing programs.

METHODS

Known urinary phase‐I metabolites of rolipram, roflumilast, and cilomilast were generated by in vitro incubations employing human liver microsomal preparations. The metabolites obtained were studied by liquid chromatography with high‐resolution/high‐accuracy tandem mass spectrometry (LC/MS/MS) and the reference product ion mass spectra of established and most relevant metabolites were utilized to provide the information necessary for comprehensive doping controls. The analytical procedure was based on conventional routine doping control assays employing enzymatic hydrolysis followed by liquid–liquid extraction and subsequent LC/MS/MS measurement.

RESULTS

Structures of diagnostic product ions and dissociation pathways of target analytes were elucidated, providing the information required for implementation into an existing test method for routine sports drug testing. The established method allowed for detection limits for the intact drugs of 1–5 ng/mL, and further assay characteristics (intraday precision 1.5–13.7%, interday precision 7.3–18.6%, recovery 20–100%, ion suppression/enhancement, and specificity) were determined. In addition, proof‐of‐concept analyses concerning roflumilast were conducted with a urine sample obtained from a COPD patient under roflumilast treatment. Copyright © 2013 John Wiley & Sons, Ltd.
Sensitive low‐pressure dielectric barrier discharge ion source
Authors: Sugiyama Masuyuki , Kumano Shun , Nishimura Kazushige , Hasegawa Hideki , Hashimoto Yuichiro
Published: April 2013

RATIONALE

We developed a novel highly sensitive soft ionization method: a low‐pressure dielectric barrier discharge ionization (LP‐DBDI) source. In this configuration, samples pass through the inside of a dielectric barrier discharge (DBD). Since samples pass through a DBD and its plasma jet, high ionization efficiency is expected. Furthermore, high transmission efficiency from the ion source to the mass spectrometer is also expected since the ion source is placed in a vacuum.

METHODS

Mass spectrometric detection was carried out in positive ion mode using an ion trap mass spectrometer. The LP‐DBDI source or a conventional atmospheric pressure chemical ionization (APCI) source was attached to the mass spectrometer. Samples were vaporized and sent to ion sources with air flowing at a constant flow rate of 1.5 L/min. The LP‐DBDI source was compared with a conventional APCI source.

RESULTS

Mass spectra of methyl salicylate, 2‐undecanone and methamphetamine were acquired using the LP‐DBDI source. Protonated molecules were mainly observed in the mass spectra. The sensitivities for methyl salicylate and 2‐undecanone obtained using the LP‐DBDI source were 44 times and 39 times higher, respectively, than those obtained using an APCI source.

CONCLUSIONS

LP‐DBDI is a soft ionization method characterized by only minor fragmentation, similar to APCI. The sensitivity of the LP‐DBDI source was found to be about 40 times higher than that of the conventional APCI source. Copyright © 2013 John Wiley & Sons, Ltd.
Using Drawings of the Brain Cell to Exhibit Expertise in Neuroscience: Exploring the Boundaries of Experimental Culture
Authors: HAY DAVID B. , WILLIAMS DARREN , STAHL DANIEL , WINGATE RICHARD J.
Published: April 2013

This paper explores the research perspective of neuroscience by documenting the brain cell (neuron) drawings of undergraduates, trainee scientists, and leading neuroscience researchers in a single research‐intensive university. Qualitative analysis, drawing‐sorting exercises, and hierarchical cluster analysis are used to answer two related questions: Are there categorical differences in drawings of participants; and if differences exist, can they be objectively recognized as measures of research experience? The analysis strongly suggests that (1) a willingness/ability to hybridize extant brain cell knowledge with imaginative conjecture grounded by experience of experimental plausibility gives rise to drawings that are recognized as being “expert signatures” by all classes of participants; (2) the drawings of PhD students and postdoctoral researchers’ are influenced by a more mechanical observation style where faithfulness to actual observation work is prioritized; and (3) while a subset of undergraduates recognize the images of “experts,” their own drawings are invariably textbook reproductions. Nevertheless, teaching interventions designed to engender a research perspective free‐up undergraduates’ creative drawing potential so that sometimes their postintervention drawings are indistinguishable from those of principal investigators. We explore the teaching implications of our data, emphasizing the distinctive role of the principal investigator who is able to index an otherwise invisible process of experimental knowledge making. © 2013 Wiley Periodicals, Inc. Sci Ed 97:468–491, 2013
Investigating College and Graduate Students’ Multivariable Reasoning in Computational Modeling
Authors: WU HSIN‐KAI , WU PAI‐HSING , ZHANG WEN‐XIN , HSU YING‐SHAO
Published: April 2013

Drawing upon the literature in computational modeling, multivariable reasoning, and causal attribution, this study aims at characterizing multivariable reasoning practices in computational modeling and revealing the nature of understanding about multivariable causality. We recruited two freshmen, two sophomores, two juniors, two seniors, four master's students, and four PhD students in atmospheric sciences as participants. Participants’ reasoning practices and understanding of multivariable causality were examined using semistructured interviews and recordings of their computer activities. Analyses show that participants with high expertise tended to take a mechanism approach to predict and identify relationships, focused more on multivariable relationships, and purposefully selected and tested variables. The findings also indicate that understanding about multiple causality involved recognition and identification of the integration rules of multiple effects and the attributes of variables (e.g., interactive and reciprocal) and relationships (e.g., direction and feedback loop). Additionally, this study suggests an interaction between participants’ reasoning practices and their understanding of multivariable causality; participants’ understanding about the integration rules and the attributes could initiate reasoning practices, and by the enactment of practices, the rules and attributes were confirmed and examined. This study provides insight into the nature of multivariable reasoning and the design of computer‐based modeling tools. © 2013Wiley Periodicals, Inc. Sci Ed 97:337–366, 2013
Learning to Assess Science in Linguistically Diverse Classrooms: Tracking Growth in Secondary Science Preservice Teachers’ Assessment Expertise
Authors: LYON EDWARD G.
Published: April 2013

Although studies have documented teachers’ growth in assessing science resulting from professional development or science methods courses, little attention has been given to growth while being prepared to assess a linguistically diverse student population. In this study, the growth of 11 secondary science preservice teachers is documented by expanding the analytical lens—looking at not only how teachers understand and plan to use assessment formatively but also their consideration of assessment design and assessment equity for English learners. Drawing on interviews, open‐ended prompts, and program artifacts collected throughout the yearlong teacher education program, quantitative and qualitative findings indicate that the teachers demonstrated the most growth in their expertise at using assessment to support learning. Although quantitative analyses indicate that changes in the teachers’ expertise at designing assessment and considering equity in assessment were not statistically significant, additional analyses revealed nuanced ways in which the teachers’ expertise grew: expanding their repertoire of assessment tasks, considering alignment of assessment tasks with learning objectives, and becoming more knowledgeable of the role of language while assessing. I argue that broadening how we analyze assessment, combined with an expanded time frame, provides new information about the extent to which teachers are prepared to assess science in linguistically diverse classrooms. © 2013 Wiley Periodicals, Inc. Sci Ed 97:442–467, 2013