bluuebunny/crossref_metadata_2025 huggingface dataset:
d
‐ and
f
‐
B
lock Transition Metal Complexes with Bulky Allyl Ligands
Authors: Chmely Stephen C. , Hanusa Timothy P.
Published: December 2011

The allyl anion (C
3
H
5
−
) is often found in combination with other ligands in organometallic complexes. Its compact size, however, means that compounds in which it is the only or principal type of ligand are frequently coordinatively unsaturated and prone to decomposition. Sterically bulky substituents (e.g.,—SiMe
3
) placed on the allyl group will increase its effective size, often enhancing the thermal, and in some cases oxidative, stability of the associated metal complexes. Compounds of the d‐ and f‐block metals containing bulky allyl ligands display a wide range of monomeric, oligomeric, and polymeric structures. Some of these complexes have no counterparts with unsubstituted allyls, and others are active polymerization catalysts. Research in this area has markedly expanded the range of metals, structural types, and associated reactions that can be incorporated into metal–allyl chemistry.
“He Couldn't Have Done It, He Was With Me!”: The Impact of Alibi Witness Age and Relationship
Authors: Dahl Leora C. , Price Heather L.
Published: December 2011

Undergraduate participants who conducted a simulated police investigation were presented with either a child (6 years old) or adult (25 years old) alibi witness, who was either the son or neighbor of the participant's suspect. Replicating previous research, participants were more likely to believe the adult neighbor alibi witness than the adult son. In fact, an alibi provided by the adult son actually proved detrimental to that suspect, as participants thought the suspect was more likely to be guilty after viewing an alibi provided by the adult son. However, child‐provided alibis reduced perceptions of suspect guilt, regardless of that child's relationship to the suspect. The child alibi witnesses were also viewed by the participants as more credible than the adult witnesses. Copyright © 2011 John Wiley & Sons, Ltd.
Structure and property relations between the polyacrylonitrile‐based prestabilized fibers and the partially carbonized fibers
Authors: Yu Meijie , Xu Yong , Wang Chengguo , Zhu Bo , Wang Yanxiang , Hu Xiuying , Lin Xue
Published: December 2011

The structure of polyacrylonitrile‐based prestabilized fibers and partially carbonized fibers prepared in air and nitrogen were studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD), the thermal properties were measured by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA), and the mechanical properties and corrosion properties resistant to concentrated sulfuric acid are also tested. Oxygen functional groups form in the fibers prestabilized in air, providing active sites for dehydrogenation and intermolecular crosslinked reactions, which facilitates the formation of turbostratic graphite structure in partially carbonized fibers. The fibers prestabilized in nitrogen and their corresponding partially carbonized fibers are brittle feature, and have comparatively low tensile strength and elongation. The fibers prestabilized in air did not change the color of concentrated sulfuric acid until being etched in it for 6 h; by contrast, the fibers prestabilized in nitrogen were dissolved out only within 1 min. It indicates that the former has better chemical stability than the latter. The present work provides direct evidence that oxygen containing structure in prestabilized fibers is an essential precondition for obtaining high property carbon fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Development of embedded assessments for learning in biotechnology: Results and design process for dissemination
Authors: Rebello Carina M. , Siegel Marcelle A. , Freyermuth Sharyn K. , Witzig Stephen B. , Izci Kemal
Published: December 2011

Embedded assessments, tasks within the context of instruction, can serve as important tools for improving teaching and learning. In this article, we report on the assessment design principles and a nine‐step development model that guided the construction of innovative embedded assessments. Using multiple sources of data—expert reviews, a conceptual test blueprint, student interviews, focus group interviews, and student responses to assessments—we were able to analyze the extent to which our assessments align with research‐based design principles. Specifically, our results demonstrate that the assessments: (a) align with learning and instructional goals; (b) are cognitively challenging; (c) support student learning; and (d) have reduced potential bias. These assessments were developed in the context of an introductory biochemistry course for nonbiochemistry majors with learning goals in areas of: scientific content, socio‐scientific issues, and evidence‐based decision making skills. The assessment design principles and development model are generalizable to other science disciplines. We discuss how the application of these design principles can generate valid and reliable embedded assessments that can be integrated into a modern classroom. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, 2011
Large‐Scale Controllable Patterning Growth of Aligned Organic Nanowires through Evaporation‐Induced Self‐Assembly
Authors: Bao Rongrong , Zhang Chengyi , Wang Zhongliang , Zhang Xiujuan , Ou Xuemei , Lee Chun‐Sing , Jie Jiansheng , Zhang Xiaohong
Published: December 2011

Organic one‐dimensional nanostructures are attractive building blocks for electronic, optoelectronic, and photonic applications. Achieving aligned organic nanowire arrays that can be patterned on a surface with well‐controlled spatial arrangement is highly desirable in the fabrication of high‐performance organic devices. We demonstrate a facile one‐step method for large‐scale controllable patterning growth of ordered single‐crystal C60 nanowires through evaporation‐induced self‐assembly. The patterning geometry of the nanowire arrays can be tuned by the shape of the covering hats of the confined curve‐on‐flat geometry. The formation of the pattern arrays is driven by a simple solvent evaporation process, which is controlled by the surface tension of the substrate (glass or Si) and geometry of the evaporation surface. By sandwiching a solvent pool between the substrate and a covering hat, the evaporation surface is confined to along the edge of the solvent pool. The geometry of the formed nanowire pattern is well defined by a surface‐tension model of the evaporation channel. This simple method is further established as a general approach that is applicable to two other organic nanostructure systems. The I–V characteristics of such a parallel, organic, nanowire‐array device was measured. The results demonstrate that the proposed method for direct growth of nanomaterials on a substrate is a feasible approach to device fabrication, especially to the fabrication of the parallel arrays of devices.
The structural heterogeneity of radial spokes in cilia and flagella is conserved
Authors: Lin Jianfeng , Heuser Thomas , Carbajal‐González Blanca I. , Song Kangkang , Nicastro Daniela
Published: December 2011

Radial spokes (RSs) are ubiquitous components of motile cilia and flagella and play an essential role in transmitting signals that regulate the activity of the dynein motors, and thus ciliary and flagellar motility. In some organisms, the 96 nm axonemal repeat unit contains only a pair of spokes, RS1 and RS2, while most organisms have spoke triplets with an additional spoke RS3. The spoke pairs in Chlamydomonas flagella have been well characterized, while spoke triplets have received less attention. Here, we used cryoelectron tomography and subtomogram averaging to visualize the three‐dimensional structure of spoke triplets in Strongylocentrotus purpuratus (sea urchin) sperm flagella in unprecedented detail. Only small differences were observed between RS1 and RS2, but the structure of RS3 was surprisingly unique and structurally different from the other two spokes. We observed novel doublet specific features that connect RS2, RS3, and the nexin‐dynein regulatory complex, three key ciliary and flagellar structures. The distribution of these doublet specific structures suggests that they could be important for establishing the asymmetry of dynein activity required for the oscillatory movement of cilia and flagella. Surprisingly, a comparison with other organisms demonstrated both that this considerable RS heterogeneity is conserved and that organisms with RS pairs contain the basal part of RS3. This conserved RS heterogeneity may also reflect functional differences between the spokes and their involvement in regulating ciliary and flagellar motility. © 2011 Wiley Periodicals Inc.
Increasing incidence of enteropathy‐associated T‐cell lymphoma in the United States, 1973‐2008
Authors: Sharaiha Reem Z. , Lebwohl Ben , Reimers Laura , Bhagat Govind , Green Peter H. , Neugut Alfred I.
Published: December 2011

BACKGROUND:

Enteropathy‐associated T‐cell lymphoma (EATL) is a rare lymphoma subtype that is strongly associated with celiac disease (CD), an autoimmune disease triggered by the ingestion of gluten. Because CD rates are increasing in the United States, the authors sought to determine whether the incidence rates of EATL also are increasing.

METHODS:

The authors identified patients with primary, pathologically confirmed lymphoma in the Surveillance, Epidemiology, and End Results database registries from 1973 to 2008. To ensure capture of all cases of EATL, the following lymphoma subtypes, limited to the small bowel, were included: non‐Hodgkin lymphoma not otherwise specified (NOS) T‐cell, peripheral T‐cell lymphoma NOS, and enteropathy type T‐cell lymphoma, and their age‐adjusted and sex‐adjusted incidence rates were calculated over time. Survival was estimated using Kaplan‐Meier curves.

RESULTS:

In total, the authors identified 161 small bowel lymphomas that were diagnosed between 1973 and 2008. The overall age‐adjusted and sex‐adjusted annual incidence for all bowel lymphomas was 0.016 per 100,000 population, which increased over the study period from 0.006 to 0.024 per 100,000 population. These tumors were most common in men (age‐adjusted incidence rate, 0.021 per 100,000) with the highest incidence rate in Hispanics (age‐adjusted incidence rate, 0.033 per 100,000). The median overall survival was 7 months. There was no difference in survival by race/ethnicity (P = .09) or sex (P = .06).

CONCLUSIONS:

The current results indicated a significant increase in the incidence of EATL in the United States, which may reflect the increasing seroprevalence of CD and better recognition of rare types of T‐cell lymphomas. The incidence may continue to rise given the large ratio of undiagnosed‐to‐diagnosed individuals with CD in the United States. Cancer 2012. © 2011 American Cancer Society.
Emerging therapies in the treatment of rheumatoid arthritis
Authors: Liu Jinqi , Mehmet Huseyin
Published: December 2011

Rheumatoid arthritis (RA) is an autoimmune disease with a significant morbidity defined by marked destruction and deformity of joints. It is characterized by autoantibody production, synovial inflammation, and erosion of the cartilage and bone. The current first‐line treatment for RA is methotrexate (MTX), an orally active disease‐modifying anti‐rheumatic drug (DMARD). Biologic DMARDs that target tumor necrosis factor (TNF) or other molecules have emerged as potent alternative therapies for patients with inadequate response to MTX therapy. Despite the huge success of MTX and/or biologics, there is still a significant unmet medical need in RA. Approximately one‐third of RA patients are nonresponsive to currently available therapies. With their critical roles in mediating multiple inflammatory pathways, small‐molecule tyrosine kinase (TK) inhibitors are gaining attention as candidates for oral RA drugs with positive outcomes for a number of late‐stage clinical trials of small‐molecule Jak (Tasocitinib) or Syk (fostamatinib) inhibitors. With the potential for attenuating multiple inflammatory pathways activated in RA, tasocitinib and fostamatinib may represent new and welcome additions to the RA therapeutic landscape. Drug Dev Res 72:805–816, 2011. © 2011 Wiley Periodicals, Inc.
Regulatory versus coding signatures of natural selection in a candidate gene involved in the adaptive divergence of whitefish species pairs (Coregonus spp.)
Authors: Jeukens Julie , Bernatchez Louis
Published: December 2011

While gene expression divergence is known to be involved in adaptive phenotypic divergence and speciation, the relative importance of regulatory and structural evolution of genes is poorly understood. A recent next‐generation sequencing experiment allowed identifying candidate genes potentially involved in the ongoing speciation of sympatric dwarf and normal lake whitefish (Coregonus clupeaformis), such as cytosolic malate dehydrogenase (MDH1), which showed both significant expression and sequence divergence. The main goal of this study was to investigate into more details the signatures of natural selection in the regulatory and coding sequences of MDH1 in lake whitefish and test for parallelism of these signatures with other coregonine species. Sequencing of the two regions in 118 fish from four sympatric pairs of whitefish and two cisco species revealed a total of 35 single nucleotide polymorphisms (SNPs), with more genetic diversity in European compared to North American coregonine species. While the coding region was found to be under purifying selection, an SNP in the proximal promoter exhibited significant allele frequency divergence in a parallel manner among independent sympatric pairs of North American lake whitefish and European whitefish (C. lavaretus). According to transcription factor binding simulation for 22 regulatory haplotypes of MDH1, putative binding profiles were fairly conserved among species, except for the region around this SNP. Moreover, we found evidence for the role of this SNP in the regulation of MDH1 expression level. Overall, these results provide further evidence for the role of natural selection in gene regulation evolution among whitefish species pairs and suggest its possible link with patterns of phenotypic diversity observed in coregonine species.
Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes
Authors: Schauer Phil A. , Low Paul J.
Published: December 2011

Transition‐metal σ‐alkynyl complexes are valuable functional materials that have found application as sructural units in the assembly of polymetallic arrays and large molecular structures, reagents for the transfer, oligomerisation or functionalisation of alkynes, magnetic or optical materials and putative components for use in a future molecular‐based electronics platform. Many σ‐alkynyl complexes are redox‐active, undergoing facile oxidation (reduction) at moderate potentials to generate radical cations (anions) in which the charge and spin density can be tuned from being largely metal‐centred to alkynyl ligand‐centred by variation of the nature of the metal, supporting ligands and alkynyl substituents. This review summarises the diverse chemical behaviour of metal‐supported σ‐alkynyl radicals, and some selected closely related systems, which can often be rationalised in terms of the distribution of electron‐spin density over the metal–alkynyl scaffold.
Electrocatalytic Oxidation of Some Hydrazine Compounds at Glassy Carbon Electrode Modified with Co‐Gluconate Complex
Authors: Casella Innocenzo G. , Contursi Michela
Published: December 2011

Cobalt oxyhydroxide modified glassy carbon electrodes (GC/Co) prepared by anodic electrodepostion in alkaline solution containing gluconate ions as ligand species have been characterized and proposed as sensing probes for the detection of hydrazine compounds. Under cyclic voltammetry and chronoamperometric conditions, the electrooxidation processes of hydrazines on the GC/Co are severely attenuated indicating strong and irreversible adsorption of the analyte on the electrode surface with subsequent formation of stable films with fouling effects on the catalytic sites. On the contrary, under flowing conditions the hydrazine compounds show well‐defined and reproducible peaks with good analytical performance. Flow injection analysis (FIA) carried out at constant applied potential of 0.3 V vs. Ag/AgCl (4 M KCl) and using a flowing stream of 0.1 M NaOH solution containing 50 µM Co2L22− as “on‐line” modifier, shows limits of detection (LODs) comprised between 0.5 µM for hydrazine and 2 µM for 1,2‐dimethyhydrazine. Regression analysis, shows linear ranges spanning over about three orders of magnitude above the detection limits with coefficients of correlation better than 0.96.
CCD‐Type Sodium Ion Image Sensor: Dynamic Observation of Ion‐Exchange Reactions of a Single Na‐Type Cation‐Exchange Resin Bead
Authors: Hattori Toshiaki , Yoshitomo Masaki , Mori Satoshi , Miyamoto Daichi , Kato Ryo , Sawada Kazuaki
Published: December 2011

A new sodium ion image sensor containing a CCD‐type semiconductor and a plasticized PVC sodium ion selective membrane was developed. The output potential slope was linear for sodium ion concentrations from 10−1 to 10−5 M. The optimum membrane possessed a near Nernstian response and high selectivity to sodium ions. The sensor can take sodium ion images with a fast response, 0.2 s per image, allowing it to easily monitor the ion‐exchange reactions of a single Na‐type cation‐exchange resin bead. It was found that Na+‐Ba2+ ion‐exchange was faster than Na+‐Ca2+ ion‐exchange in the initial period.
Sediment modelling with fine temporal and spatial resolution for a hilly catchment
Authors: Elliott A. H. , Oehler F. , Schmidt J. , Ekanayake J. C.
Published: December 2011

The suitability of the physically based model SHETRAN for simulating sediment generation and delivery with a high degree of spatial (20 m) and temporal (sub‐hourly) resolution was assessed through application of the model to a 167‐km2 catchment leading to an estuary in New Zealand. By subdividing the catchment and conducting calculations on a computer cluster for a 6‐month hydrology initialisation period, it was possible to simulate a large rainfall event and its antecedent conditions in 24 h of computation time. The model was calibrated satisfactorily to catchment outlet flow and sediment flux for a large rainfall event in two subcatchments (~2 km2). Validation for a separate subcatchment was successful for flow (Nash–Sutcliff efficiency of 0.84) with a factor 2.1 over‐prediction for sediment load. Validation for sediment at full catchment scale using parameters from the subcatchment scale was good for flow but poor for sediment, with gross under‐estimation of the dominant stream sources of sediment. After recalibration at catchment scale, validation for a separate event gave good results for flow (Nash–Sutcliff efficiency of 0.93) and sediment load within a factor of two of measurements. An exploratory spatially explicit landslide model was added to SHETRAN, but it was not possible to test this fully because no landslides were observed in the study period. Application to climate change highlighted the non‐linear response to extreme rainfall. However, full exploration of land use and climate change and the evaluation of uncertainty were severely constrained by computational limitations. Subdivision of the catchment with separate stream routing is suggested as a way forward to overcome these limitations. Copyright © 2011 John Wiley & Sons, Ltd.
Phase Separation Dynamics of Aqueous Poly [(2‐ethoxy) ethoxy ethyl vinyl ether] Solutions as Explored using the Laser T‐Jump Technique Combined With Photometry
Authors: Tsuboi Yasuyuki , Kikuchi Kanae , Kitamura Noboru , Shimomoto Hiroaki , Kanaoka Shokyoku , Aoshima Sadahito
Published: December 2011

Poly[(2‐ethoxy) ethoxy ethyl vinyl ether] (poly(EOEOVE)) is a representative thermoresponsive polymer in aqueous solution for which the time constants of the phase separation (PS) are determined with high accuracy. It is revealed that the PS dynamics of the polymer are entirely different from those of the poly(N‐isopropylacrylamide) (PNIPAM) system, which is an alternative representative thermoresponsive polymer. Poly(EOEOVE) exhibits complicated PS behavior that is described using double exponential functions. The PS of poly(EOEOVE) is much faster than the PS of PNIPAM in aqueous solutions and becomes faster with increasing concentration of the polymer. PS behavior that is particular to the present system is successfully understood within the framework of the aggregation mechanism.
On the strong stability of symplectic matrices
Authors: Dosso M. , Sadkane M.
Published: December 2011

The strong stability of a symplectic matrix is investigated from algorithmic and numerical viewpoints using a theory developed by S.K. Godunov. This theory is based on a different formulation of the Krein‐Gelfand‐Lidskii characterization of strong stability, better suited for numerical calculations. Copyright © 2011 John Wiley & Sons, Ltd.
Reactive murine lymph nodes uniquely permit parenchymal access for T cells that enter via the afferent lymphatics
Authors: Eidsmo Liv , Stock Angus T , Heath William R , Bedoui Sammy , Carbone Francis R
Published: December 2011

Whereas naïve T cells access the lymph nodes predominantly via the high endothelial venules, their effector counterparts can also enter via the afferent lymphatics. It is unclear if such cells are confined to the lymphatic spaces during their transit through the lymph node or whether they can access the lymphocyte‐ and dendritic cell‐rich parenchyma with its potentially stimulatory environment. We used a flank HSV inoculation model that featured neuronal‐mediated movement of virus to distinct areas of skin to study the lymphatic‐mediated transit of activated T cells between different skin‐draining lymph nodes. These experiments showed that activated T cells released from the brachial lymph node, draining the primary site of inoculation, entered the downstream axillary lymph node. These activated T cells accessed the subcapsular areas of the axillary lymph node via lymphatic vessels exiting the upstream brachial node regardless of whether the former drained skin that was associated with active infection. However, T cells remained within the sinusoidal network of the axillary lymph node unless it was directly associated with peripheral infection. Thus, activated T cells that enter a given lymph node using the afferent lymphatics do not have automatic access to the parenchyma unless it is a reactive node involved with peripheral inflammation or infection. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Salicylaldiminato nickel(II) catalysts with 5‐halo‐3‐methoxy groups for ethylene polymerization
Authors: Kolhatkar Nikhil A. , Monfette Amber M. , Lin Shuo , Miri Massoud J.
Published: December 2011

Two neutral salicylaldiminato methyl pyridine nickel(II) complexes were synthesized and evaluated for ethylene polymerization. Each catalyst bears a methoxy group in the 3‐position and a halogen atom in the 5‐position of the salicyl ligand, chlorine in case of catalyst 3a and bromine in 3b. Molecular structures of the catalysts were obtained by X‐ray crystallography. The resulting polymerization activities, for example, indicated by a maximum turnover frequency of 4,870 mol ethylene/(mol Ni × h) for 1‐h runs obtained with 3a, were higher than those of similar catalysts at comparable conditions reported in the literature. Catalyst 3a was slightly more active than catalyst 3b. The polymers are branched as measured by 1H NMR and 13C NMR. This was also reflected in the melting temperatures between 76 and 113 °C obtained by differential scanning calorimetry. By using gel permeation chromatography measurements, it was determined that the Mw of the polymers ranges between about 5,400 and 21,600 g/mol. In particular, the effect of the polymerization temperature on the catalyst activity, degree of branching, and molecular weight properties has been described. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Control of aggregate formation in poly(3‐hexylthiophene) by solvent, molecular weight, and synthetic method
Authors: Scharsich Christina , Lohwasser Ruth H. , Sommer Michael , Asawapirom Udom , Scherf Ullrich , Thelakkat Mukundan , Neher Dieter , Köhler Anna
Published: December 2011

Aggregate formation in poly(3‐hexylthiophene) depends on molecular weight, solvent, and synthetic method. The interplay of these parameters thus largely controls device performance. In order to obtain a quantitative understanding on how these factors control the resulting electronic properties of P3HT, we measured absorption in solution and in thin films as well as the resulting field effect mobility in transistors. By a detailed analysis of the absorption spectra, we deduce the fraction of aggregates formed, the excitonic coupling within the aggregates, and the conjugation length within the aggregates, all as a function of solvent quality for molecular weights from 5 to 19 kDa. From this, we infer in which structure the aggregated chains pack. Although the 5 kDa samples form straight chains, the 11 and 19 kDa chains are kinked or folded, with conjugation lengths that increase as the solvent quality reduces. There is a maximum fraction of aggregated chains (about 55 ± 5%) that can be obtained, even for poor solvent quality. We show that inducing aggregation in solution leads to control of aggregate properties in thin films. As expected, the field‐effect mobility correlates with the propensity to aggregation. Correspondingly, we find that a well‐defined synthetic approach, tailored to give a narrow molecular weight distribution, is needed to obtain high field effect mobilities of up to 0.01 cm2/Vs for low molecular weight samples (=11 kDa), while the influence of synthetic method is negligible for samples of higher molecular weight, if low molecular weight fractions are removed by extraction. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Lung function among infants born preterm, with or without bronchopulmonary dysplasia
Authors: Sanchez‐Solis Manuel , Garcia‐Marcos Luis , Bosch‐Gimenez Vicente , Pérez‐Fernandez Virginia , Pastor‐Vivero Maria D. , Mondéjar‐Lopez Pedro
Published: December 2011

Objective

Both healthy preterm infants and those with bronchopulmonary dysplasia (BPD) have poor lung function during childhood and adolescence, although there is no evidence whether prematurity alone explains the reduction in lung function found in BPD infants. Our study seeks to know if lung function, measured in infancy by means of rapid thoracic compression with raised volume technique, is different between preterm infants with and without BPD.

Methods

Lung function was measured in 43 preterm infants with BPD and in 32 preterm infants without BPD at a chronological age range of 2–28 months. Forced vital capacity (FVC), forced expiratory volume at 0.5 sec, and forced expiratory flows at 50, 75, 85%, and 25–75% of FVC were obtained from maximal expiratory volume curves by means of rapid thoracic compression with raised volume technique. Maximal flow at functional residual capacity was measured using rapid thoracic compression at tidal volume. Multiple regression analysis and generalized least squares (GLS) random‐effects regression model were used to control for variables such as gender, weeks of gestation, age, birth weight, and tobacco smoke exposure. A sub‐analysis was performed in infants born at 28+ weeks of gestation.

Results

BPD was associated to significantly lower flows (regression coefficients: −0.51, −0.54, −57, −0.53, and −0.82, respectively for FEF50, FEF75, FEF85, FEF25–75). This association was driven by males and maintained in the subgroup of infants born at 28+ weeks of gestation.

Conclusion

BPD is associated with an additional decrease of lung function during the first 2 years of life in infants born preterm. Pediatr Pulmonol. 2012; 47:674–681. © 2011 Wiley Periodicals, Inc.
The Sensitivity of Lung Disease Surrogates in Detecting Chest CT Abnormalities in Children With Cystic Fibrosis
Authors: Sanders Don B. , Li Zhanhai , Rock Michael J. , Brody Alan S. , Farrell Philip M.
Published: December 2011

Rationale

Chest CT scans detect structural abnormalities in children with cystic fibrosis (CF), even when pulmonary function tests (PFTs) are normal. The use of chest CT is limited in clinical practice, because of concerns over expense, increased resource utilization, and radiation exposure. Quantitative chest radiography scores are useful in detecting mild lung disease, but whether they are sensitive to the presence of CT scan abnormalities has not been evaluated.

Objective

To determine in a cross‐sectional study if quantitative chest radiography is a more sensitive marker of chest CT abnormalities than other lung disease surrogates.

Methods

Brody chest CT scores were calculated for 81 children enrolled in the Wisconsin CF Neonatal Screening Project. We determined the sensitivity for Wisconsin (WCXR) and Brasfield (BCXR) chest radiography scores, PFTs, positive cultures forP. aeruginosa(PA), and parental report of symptoms to detect a Brody score worse than the median score for study participants.

Measurements and Main Results

The mean FEV1for the study population was 91% predicted. Abnormal WCXR and BCXR scores had the highest sensitivity to detect a chest CT score worse than the median; abnormal PFTs, parental report of symptoms, and the presence of PA had much lower sensitivity (P < 0.001).

Conclusions

In this cross sectional study, quantitative chest radiography has excellent sensitivity to detect an abnormal chest CT and may have a role in monitoring lung disease progression in children with CF. Pediatr Pulmonol. 2012; 47:567–573. © 2011 Wiley Periodicals, Inc.
Validating the vitality strategy for fighting drug resistance
Authors: Singh Nidhi , Frushicheva Maria P. , Warshel Arieh
Published: December 2011

The current challenge in designing effective drugs against HIV‐1 is to find novel candidates with high potency, but with a lower susceptibility to mutations associated with drug resistance. Trying to address this challenge, we developed in our previous study (Ishikita and Warshel, Angew Chem Int Ed Engl 2008; 47:697–700) a novel computational strategy for fighting drug resistance by predicting the likely moves of the virus through constraints on binding and catalysis. This has been based on calculating the ratio between the vitality values ((Ki kcat/KM)mutant/(Ki kcat/KM)wild‐type) and using it as a guide for predicting the moves of the virus. The corresponding calculations of the binding affinity, Ki , were carried out using the semi‐macroscopic version of the protein dipole Langevin dipole (PDLD/S) in its linear response approximation (LRA) in its β version (PDLD/S‐LRA/β). We also calculate the proteolytic efficiency, kcat/KM, by evaluating the transition state (TS) binding free energies using the PDLD/S‐LRA/β method. Here we provide an extensive validation of our strategy by calculating the vitality of six existing clinical and experimental drug candidates. It is found that the computationally determined vitalities correlate reasonably well with those derived from the corresponding experimental data. This indicates that the calculated vitality may be used to identify mutations that would be most effective for the survival of the virus. Thus, it should be possible to use our approach in screening for mutations that would provide the most effective resistance to any proposed antiviral drug. This ability should be very useful in guiding the design of drug molecules that will lead to the slowest resistance. Proteins 2012; © 2011 Wiley Periodicals, Inc.
Molecular insight into substrate recognition by human cytosolic sialidase NEU2
Authors: Mozzi Alessandra , Mazzacuva Pietro , Zampella Giuseppe , Forcella Matilde Emma , Fusi Paola Alessandra , Monti Eugenio
Published: December 2011

Sialidases or neuramidases are glycoside hydrolases removing terminal sialic acid residues from sialo‐glycoproteins and sialo‐glycolipids. Viral neuraminidases (NAs) have been extensively characterized and represent an excellent target for antiviral therapy through the synthesis of a series of competitive inhibitors that block the release of newly formed viral particles from infected cells. The human cytosolic sialidase NEU2 is the only mammalian enzyme structurally characterized and represents a valuable model to study the specificity of novel NA inhibitory drugs. Moreover, the availability of NEU2 3D structure represents a pivotal step toward the characterization of the molecular basis of natural substrates recognition by the enzyme. In this perspective, we have carried out a study of molecular docking of NEU2 active site using natural substrates of increasing complexity. Moreover, selective mutations of the residues putatively involved into substrate(s) interaction/recognition have been performed, and the resulting mutant enzymes have been preliminary tested for their catalytic activity and substrate specificity. We found that Q270 is involved in the binding of the disaccharide α(2,3) sialyl‐galactose, whereas K45 and Q112 bind the distal glucose of the trisaccharide α(2,3) sialyl‐lactose, corresponding to the oligosaccharide moiety of GM3 ganglioside. In addition, E218, beside D46, is proved to be a key catalytic residue, being, together with Y334, the second member of the nucleophile pair required for the catalysis. Overall, our results point out the existence of a dynamic network of interactions that are possibly involved in the recognition of the glycans bearing sialic acid. Proteins 2012; © 2011 Wiley Periodicals, Inc.
The effects of rigid motions on elastic network model force constants
Authors: Lezon Timothy R.
Published: December 2011

Elastic network models provide an efficient way to quickly calculate protein global dynamics from experimentally determined structures. The model's single parameter, its force constant, determines the physical extent of equilibrium fluctuations. The values of force constants can be calculated by fitting to experimental data, but the results depend on the type of experimental data used. Here, we investigate the differences between calculated values of force constants and data from NMR and X‐ray structures. We find that X‐ray B factors carry the signature of rigid‐body motions, to the extent that B factors can be almost entirely accounted for by rigid motions alone. When fitting to more refined anisotropic temperature factors, the contributions of rigid motions are significantly reduced, indicating that the large contribution of rigid motions to B factors is a result of over‐fitting. No correlation is found between force constants fit to NMR data and those fit to X‐ray data, possibly due to the inability of NMR data to accurately capture protein dynamics. Proteins 2012; © 2011 Wiley Periodicals, Inc.
Restoring cerebral dopamine homeostasis by electrical forepaw stimulation: An FMRI study
Authors: Chen Y. Iris , Ren Jia‐Qian , Kaptchuk Ted J. , Kwong Kenneth K.
Published: December 2011

Deviation of dopamine homeostasis is known to be associated with disorders like drug addiction and Parkinson's disease. As dopamine function is tightly regulated within the basal ganglia circuitry, cortical perturbation would lead to modulation of dopaminergic activity in the striatum. We proposed and tested if somatosensory activity such as forepaw stimulation could modulate dopaminergic function. Specifically, we tested in rats if electrical forepaw stimulation (EFS) could attenuate dopamine release in the brain if dopamine is excessive, and boost dopamine release if dopamine is deficient. We had previously demonstrated that EFS effectively attenuated excessive DA concentration in the striatum. We now show in this manuscript with fMRI that EFS boosted DA release on two DA deficient conditions: (1) with quinpirole challenge, and (2) partial Parkinsonism model (PD). Quinpirole alone decreased dopamine release and thus the cerebral blood volume (CBV) that was restored by EFS. EFS also succeeded in increasing CBV in the basal‐ganglia circuitry of the PD rats, but not in the controls. Context‐dependent connectivity analysis showed increased connectivity during the basal state in the PD rats, compared with the controls. This “enhanced” yet abnormal connectivity of PD rats was reduced post‐EFS. Our results suggest that EFS resets the deficient DA system by partially increasing DA release, in the meanwhile lessening the need for recruiting extra functional network in the basal ganglia circuitry. This study shows not only the capacity of peripheral stimulation to perturb neurotransmitter function, but also the potential of peripheral stimulation to restore neurotransmitter homeostasis. Synapse, 2012. © 2011 Wiley Periodicals, Inc.
Dendritic morphology of neurons in prefrontal cortex and ventral hippocampus of rats with neonatal amygdala lesion
Authors: Vázquez‐Roque Rubén Antonio , Solis Oscar , Camacho‐Abrego Israel , Rodríguez‐Moreno Antonio , De La Cruz Fidel , Zamudio Sergio , Flores Gonzalo
Published: December 2011

Neonatal basolateral amygdala (nBLA) lesions in rats have been widely used as a neurodevelopmental model that mimics schizophrenia‐like behaviors. Recently, we reported that nBLA lesions result in significant decreases in the dendritic spine number of layer 3 prefrontal cortex (PFC) pyramidal cells and medium spiny neurons of the nucleus accumbens (NAcc), which all changes after puberty. At present, we aimed to evaluate the effect of this lesion in pyramidal neurons of CA1 of the ventral hippocampus (VH) and layer 5 of the PFC. In order to assess the effects of nBLA lesions on the dendritic morphology of the PFC and VH neurons, we carried out nBLA lesions in rats on postnatal day (PD) 7, and then we studied the dendritic morphology of these two limbic subregions at prepubertal (PD35) and postpubertal (PD60) ages. Dendritic characteristics were measured by Golgi‐Cox procedure followed by Sholl analysis. We also evaluated the effects of nBLA lesions on the prepulse inhibition (PPI) and acoustic startle responses. The nBLA lesion induced a significant increase in dendritic length of layer 5 pyramidal neurons of the PFC at both ages, with a decrease in the dendritic spines density after puberty. The spine density of CA1 VH pyramidal neurons showed significant decreases at both ages. PPI was decreased in adulthood in the animals with an nBLA lesion. These results show that an nBLA lesion alters the dendritic morphology at the level of the PFC and VH in distinct ways before puberty, suggesting a disconnection between these limbic structures at an early age, and increasing our understanding of the implications of the VH in early amygdala dysfunction in schizophrenia. Synapse, 2012. © 2011 Wiley Periodicals, Inc.
Positron emission tomography experience with 2‐[18F]fluoro‐3‐(2(s)‐azetidinylmethoxy)pyridine (2‐[18F]fa) in the living human brain of smokers with paranoid schizophrenia
Authors: Brašić James Robert , Cascella Nicola , Kumar Anil , Zhou Yun , Hilton John , Raymont Vanessa , Crabb Andrew , Guevara Maria Rita , Horti Andrew G. , Wong Dean Foster
Published: December 2011

Utilizing postmortem data (Breese et al. [2000] Neuropsychopharmacology 23:351–364), we hypothesized that the densities of high‐affinity neuronal α4β2 nicotinic acetylcholine receptors (nAChRs) in the brain exist in a continuum from highest to lowest as follows: smokers without schizophrenia > smokers with schizophrenia > nonsmokers without schizophrenia > nonsmokers with schizophrenia. Application of the Kruskal‐Wallis Test (Statacorp, 2003) to the postmortem data (Breese et al. [2000] Neuropsychopharmacology 23:351‐364) confirmed the hypothesized order in the cortex and the hippocampus and attained significance in the caudate and the thalamus. Positron emission tomography (PET) was performed for 60 min at 6 h after the intravenous administration of 444 megabequerels [MBq] (12 mCi) 2‐[18F]fluoro‐3‐(2(S)‐azetidinylmethoxy)pyridine (2‐[18F]FA), a radiotracer for high‐affinity neuronal α4β2 nAChRs, as a bolus plus continuous infusion to 10 adults (seven men and three women) (six smokers including five with paranoid schizophrenia and four nonsmokers) ranging in age from 22 to 56 years (mean 40.1, standard deviation 13.6). The thalamic nondisplaceable binding potential (BPND) was 1.32 ± 0.19 (mean ± standard deviation) for healthy control nonsmokers; 0.50 ± 0.19 for smokers with paranoid schizophrenia; and 0.51 for the single smoker without paranoid schizophrenia. The thalamic BPNDs of nonsmokers were significantly higher than those of smokers who smoked cigarettes a few hours before the scans (P = 0.0105) (StataCorp, 2003), which was likely due to occupancy of nAChRs by inhaled nicotine in smokers. Further research is needed to rule out the effects of confounding variables. Synapse 2012. © 2011Wiley Periodicals, Inc.
Chest X‐ray after Tracheostomy Is Not Necessary Unless Clinically Indicated
Authors: Tobler William D. , Mella Juan R. , Ng Joanna , Selvam Anand , Burke Peter A. , Agarwal Suresh
Published: December 2011

Background

Chest radiography is routinely used post‐tracheostomy to evaluate for complications. Often, the chest X‐ray findings do not change clinical management. The present study was conducted to evaluate the utility of post‐tracheostomy X‐rays.

Method

This retrospective review of 255 patients was performed at a single‐center, university, level I trauma center. All patients underwent tracheostomy and were evaluated for postprocedure complications.

Results

Of the 255 patients, 95.7% had no change in postprocedure chest X‐ray findings. New significant chest X‐ray findings were found in 4.3% of patients, including subcutaneous emphysema, pneumothorax, and new significant consolidation. Only three of these patients required change in clinical management, and all changes were based on clinical presentation alone.

Conclusions

Routine chest X‐ray following tracheostomy fails to provide additional information beyond clinical examination. Therefore radiographic examination should be performed only after technically difficult procedures or if the patient experiences clinical deterioration. Significant cost savings and minimization of radiation exposure can be achieved when chest radiography after tracheostomy is performed exclusively for clinical indications.
Epiploic Appendagitis: Is There Need for Surgery to Confirm Diagnosis in Spite of Clinical and Radiological Findings?
Authors: Hasbahceci Mustafa , Erol Cengiz , Seker Mehmet
Published: December 2011

Background

The present retrospective study was conducted to review the authors’ experience and describe clinical and radiologic features of epiploic appendagitis (EA), which is an uncommon, self‐limiting clinical entity mimicking acute appendicitis and diverticulitis. Awareness of the features of EA would allow a correct diagnosis and avoid unnecessary surgical interventions.

Methods

Patients diagnosed as EA in one regional medical center between June 2006 and June 2010 were included. Clinical, laboratory, and imaging features of EA were studied, with particular attention to its unique radiologic appearances.

Results

Twenty patients (13 men and 7 women; average age 43.2 years) diagnosed with EA were included in the study. Localized abdominal pain without nausea, vomiting, and fever were the major presenting symptoms for all patients. Laboratory blood tests were normal, except in one patient with leukocytosis and two patients with increased serum C‐reactive protein (CRP) levels. A noncompressible hyperechoic ovoid mass with hypoechoic border and without central blood flow on Doppler ultrasound (US) was detected in five of six patients. In all patients, the computed tomography (CT) scans revealed an ovoid fatty mass with hyperattenuating rim and disproportionate adjacent fat stranding. Central dot sign, concomitant old infarct, and lobulation were present in 75%, 20%, and 10% of the patients, respectively. All of the patients were treated conservatively. No recurrences occurred during the follow‐up period (average: 24.8 months) in 18 (90%) of the patients.

Conclusions

In patients with localized abdominal pain without other symptoms, diagnosis of EA should be considered. Recognizing the US and CT features of EA may allow an accurate diagnosis and avoid unnecessary surgery.
Effects of mud fiddler crabs (Uca pugnax) on the recruitment of halophyte seedlings in salt marsh dieback areas of Cape Cod (Massachusetts, USA)
Authors: Smith Stephen M. , Tyrrell Megan C.
Published: December 2011

The effects of bioturbation by the mud fiddler crab (Uca pugnax) on salt marsh seedling recruitment were investigated experimentally in this study. Burrowing and foraging activity caused a large amount of soil disturbance, which in turn negatively impacted the establishment of seedlings. Either seeds did not germinate or seedlings were uprooted or buried. Although the majority of the published literature suggests a positive influence of Uca spp. on salt marsh plant growth, at high densities they have the potential to hinder the re‐colonization of areas made bare by previous disturbance. This study illustrates the perhaps underappreciated role that bioturbators can have on vegetation patterns in salt marshes and other ecosystems.
Multifunctional Acyltransferases from Tetrahymena thermophila
Authors: Biester Eva‐Maria , Hellenbrand Janine , Frentzen Margrit
Published: December 2011

Multifunctional acyltransferases are able to catalyze the esterification of various acyl‐acceptors with activated fatty acids. Here we describe the identification of four proteins from Tetrahymena thermophila that share certain properties with mammalian acyltransferases regarding their predicted transmembrane structure, their molecular mass and the typical acyltransferase motif. Expression of the Tetrahymena sequences results in production of triacylglycerols and wax esters in recombinant yeast when appropriate substrates are provided. The in vitro characterization shows, that these enzymes are capable of esterifying different acyl‐acceptors including fatty alcohols, diols, diacylglycerols and isoprenols with acyl‐CoA thioesters. Based on these catalytic activities and the sequence similarities of the Tetrahymena proteins with acyl‐CoA:diacylglycerol acyltransferase 2 (DGAT2) family members, we conclude that we identified a new group of DGAT2‐related multifunctional acyltransferases from protozoan organisms.
Fish Oil Supplementation Improves Neutrophil Function During Cancer Chemotherapy
Authors: Bonatto Sandro J. R. , Oliveira Heloisa H. P. , Nunes Everson A. , Pequito Daniele , Iagher Fabiola , Coelho Isabela , Naliwaiko Katya , Kryczyk Marcelo , Brito Gleisson A. P. , Repka João , Sabóia Luciano V. , Fukujima George , Calder Philip C. , Fernandes Luiz C.
Published: December 2011

Cancer chemotherapy is associated with neutropenia and impaired neutrophil function. This study aimed to investigate whether supplementation with low dose fish oil (FO), providing n‐3 polyunsaturated fatty acids, in cancer patients receiving chemotherapy after surgical tumor (mainly gastrointestinal) removal is able to improve the function of blood neutrophils. Patients (n = 38) receiving chemotherapy (5‐fluorouracil and leucovorin) were randomized into two groups; one group (control) did not receive a supplement, while the other group (FO) received 2 g FO/day for 8 weeks; the FO provided 0.3 g eicosapentaenoic acid plus 0.4 g docosahexaenoic acid per day. Patients in the control group lost an average of 2.5 kg of weight over the 8 weeks of the study. The number of blood polymorphonuclear cells (PMNC), mainly neutrophils, and their functions (phagocytosis and hydrogen peroxide production) decreased in the control group (average decreases of approximately 30, 45 and 17%, respectively). FO prevented these decreases and actually increased body weight (average of 1.7 kg weight gain; p < 0.002 vs. control group), PMNC number (average 29% increase), phagocytosis (average 14% increase) and superoxide production (average 28% increase). FO may be useful in preventing chemotherapy‐induced decline in neutrophil number and function.