bluuebunny/crossref_metadata_2025 huggingface dataset:
Top performers are not the most impressive when extreme performance indicates unreliability
Authors: Denrell Jerker , Liu Chengwei
Published: May 2012

The relationship between performance and ability is a central concern in the social sciences: Are the most successful much more able than others, and are failures unskilled? Prior research has shown that noise and self-reinforcing dynamics make performance unpredictable and lead to a weak association between ability and performance. Here we show that the same mechanisms that generate unpredictability imply that extreme performances can be relatively uninformative about ability. As a result, the highest performers may not have the highest expected ability and should not be imitated or praised. We show that whether higher performance indicates higher ability depends on whether extreme performance could be achieved by skill or requires luck.
Accurate de novo structure prediction of large transmembrane protein domains using fragment-assembly and correlated mutation analysis
Authors: Nugent Timothy , Jones David T.
Published: May 2012

A new de novo protein structure prediction method for transmembrane proteins (FILM3) is described that is able to accurately predict the structures of large membrane proteins domains using an ensemble of two secondary structure prediction methods to guide fragment selection in combination with a scoring function based solely on correlated mutations detected in multiple sequence alignments. This approach has been validated by generating models for 28 membrane proteins with a diverse range of complex topologies and an average length of over 300 residues with results showing that TM-scores > 0.5 can be achieved in almost every case following refinement using MODELLER. In one of the most impressive results, a model of mitochondrial cytochrome
c
oxidase polypeptide I was obtained with a TM-score > 0.75 and an rmsd of only 5.7 Å over all 514 residues. These results suggest that FILM3 could be applicable to a wide range of transmembrane proteins of as-yet-unknown 3D structure given sufficient homologous sequences.
Heart wall myofibers are arranged in minimal surfaces to optimize organ function
Authors: Savadjiev Peter , Strijkers Gustav J. , Bakermans Adrianus J. , Piuze Emmanuel , Zucker Steven W. , Siddiqi Kaleem
Published: May 2012

Heart wall myofibers wind as helices around the ventricles, strengthening them in a manner analogous to the reinforcement of concrete cylindrical columns by spiral steel cables [Richart FE, et al. (1929) Univ of Illinois, Eng Exp Stn Bull 190]. A multitude of such fibers, arranged smoothly and regularly, contract and relax as an integrated functional unit as the heart beats. To orchestrate this motion, fiber tangling must be avoided and pumping should be efficient. Current models of myofiber orientation across the heart wall suggest groupings into sheets or bands, but the precise geometry of bundles of myofibers is unknown. Here we show that this arrangement takes the form of a special minimal surface, the generalized helicoid [Blair DE, Vanstone JR (1978)
Minimal Submanifolds and Geodesics
13–16], closing the gap between individual myofibers and their collective wall structure. The model holds across species, with a smooth variation in its three curvature parameters within the myocardial wall providing tight fits to diffusion magnetic resonance images from the rat, the dog, and the human. Mathematically it explains how myofibers are bundled in the heart wall while economizing fiber length and optimizing ventricular ejection volume as they contract. The generalized helicoid provides a unique foundation for analyzing the fibrous composite of the heart wall and should therefore find applications in heart tissue engineering and in the study of heart muscle diseases.
Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley
Authors: Scanlon Bridget R. , Faunt Claudia C. , Longuevergne Laurent , Reedy Robert C. , Alley William M. , McGuire Virginia L. , McMahon Peter B.
Published: May 2012

Aquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ∼50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains results in sustainable pumpage, whereas lower recharge in the central and southern High Plains has resulted in focused depletion of 330 km
3
of fossil groundwater, mostly recharged during the past 13,000 y. Depletion is highly localized with about a third of depletion occurring in 4% of the High Plains land area. Extrapolation of the current depletion rate suggests that 35% of the southern High Plains will be unable to support irrigation within the next 30 y. Reducing irrigation withdrawals could extend the lifespan of the aquifer but would not result in sustainable management of this fossil groundwater. The Central Valley is a more dynamic, engineered system, with north/south diversions of surface water since the 1950s contributing to ∼7× higher recharge. However, these diversions are regulated because of impacts on endangered species. A newly developed Central Valley Hydrologic Model shows that groundwater depletion since the 1960s, totaling 80 km
3
, occurs mostly in the south (Tulare Basin) and primarily during droughts. Increasing water storage through artificial recharge of excess surface water in aquifers by up to 3 km
3
shows promise for coping with droughts and improving sustainability of groundwater resources in the Central Valley.
Templates are available to model nearly all complexes of structurally characterized proteins
Authors: Kundrotas Petras J. , Zhu Zhengwei , Janin Joël , Vakser Ilya A.
Published: May 2012

Traditional approaches to protein–protein docking sample the binding modes with no regard to similar experimentally determined structures (templates) of protein–protein complexes. Emerging template-based docking approaches utilize such similar complexes to determine the docking predictions. The docking problem assumes the knowledge of the participating proteins’ structures. Thus, it provides the possibility of aligning the structures of the proteins and the template complexes. The progress in the development of template-based docking and the vast experience in template-based modeling of individual proteins show that, generally, such approaches are more reliable than the free modeling. The key aspect of this modeling paradigm is the availability of the templates. The current common perception is that due to the difficulties in experimental structure determination of protein–protein complexes, the pool of docking templates is insignificant, and thus a broad application of template-based docking is possible only at some future time. The results of our large scale, systematic study show that, surprisingly, in spite of the limited number of protein–protein complexes in the Protein Data Bank, docking templates can be found for complexes representing almost all the known protein–protein interactions, provided the components themselves have a known structure or can be homology-built. About one-third of the templates are of good quality when they are compared to experimental structures in test sets extracted from the Protein Data Bank and would be useful starting points in modeling the complexes. This finding dramatically expands our ability to model protein interactions, and has far-reaching implications for the protein docking field in general.
Noninvasive in vivo optical detection of biofilm in the human middle ear
Authors: Nguyen Cac T. , Jung Woonggyu , Kim Jeehyun , Chaney Eric J. , Novak Michael , Stewart Charles N. , Boppart Stephen A.
Published: May 2012

Otitis media (OM), a middle-ear infection, is the most common childhood illness treated by pediatricians. If inadequately treated, OM can result in long-term chronic problems persisting into adulthood. Children with chronic OM or recurrent OM often have conductive hearing loss and communication difficulties and require surgical treatment. Tympanostomy tube insertion, the placement of a small drainage tube in the tympanic membrane (TM), is the most common surgical procedure performed in children under general anesthesia. Recent clinical studies have shown evidence of a direct correspondence between chronic OM and the presence of a bacterial biofilm within the middle ear. Biofilms are typically very thin and cannot be recognized using a regular otoscope. Here we report the use of optical coherent ranging techniques to noninvasively assess the middle ear to detect and quantify biofilm microstructure. This study involves adults with chronic OM, which is generally accepted as a biofilm-related disease. Based on more than 18,537 optical ranging scans and 742 images from 13 clinically infected patients and 7 normal controls using clinical findings as the gold standard, all middle ears with chronic OM showed evidence of biofilms, and all normal ears did not. Information on the presence of a biofilm, along with its structure and response to antibiotic treatment, will not only provide a better fundamental understanding of biofilm formation, growth, and eradication in the middle ear, but also may provide much-needed quantifiable data to enable early detection and quantitative longitudinal treatment monitoring of middle-ear biofilms responsible for chronic OM.
Distinct CD4
+
helper T cells involved in primary and secondary responses to infection
Authors: Weber K. Scott , Li Qi-Jing , Persaud Stephen P. , Campbell Jeff D. , Davis Mark M. , Allen Paul M.
Published: May 2012

Helper T cells are critical for protective immunity, CD8
+
T-cell memory, and CD4
+
recall responses, but whether the same or distinct CD4
+
T cells are involved in these responses has not been established. Here we describe two CD4
+
T cells, LLO118 and LLO56, specific for an immunodominant
Listeria monocytogenes
epitope, with dramatically different responses to primary and secondary infection. Comparing in vivo responses, LLO118 T cells proliferate more strongly to primary infection, whereas surprisingly, LLO56 has a superior CD4
+
recall response to secondary infection. LLO118 T cells provide more robust help for CD8
+
T-cell responses to secondary infection than LLO56. We found no detectable differences in antigen sensitivity, but naive LLO118 T cells have much lower levels of CD5 and their T-cell receptor levels are dramatically down-regulated after their strong primary response. Thus, distinct CD4
+
helper T cells are specialized to help either in primary or secondary responses to infection.
Small RNA binding to the lateral surface of Hfq hexamers and structural rearrangements upon mRNA target recognition
Authors: Sauer Evelyn , Schmidt Steffen , Weichenrieder Oliver
Published: May 2012

The bacterial Sm-like protein Hfq is a central player in the control of bacterial gene expression. Hfq forms complexes with small regulatory RNAs (sRNAs) that use complementary “seed” sequences to target specific mRNAs. Hfq forms hexameric rings, which preferably bind uridine-rich RNA 3′ ends on their proximal surface and adenine-rich sequences on their distal surface. However, many reported properties of Hfq/sRNA complexes could not be explained by these RNA binding modes. Here, we use the RybB sRNA to identify the lateral surface of Hfq as a third, independent RNA binding surface. A systematic mutational analysis and competition experiments demonstrate that the lateral sites have a preference for and are sufficient to bind the sRNA “body,” including the seed sequence. Furthermore, we detect significant structural rearrangements of the Hfq/sRNA complex upon mRNA target recognition that lead to a release of the seed sequence, or of the entire sRNA molecule in case of an unfavorable 3′ end. Consequently, we propose a molecular model for the Hfq/sRNA complex, where the sRNA 3′ end is anchored in the proximal site of Hfq, whereas the sRNA body, including the seed sequence, is bound by up to six of the lateral sites. In contrast to previously proposed arrangements, the presented model explains how Hfq can protect large parts of the sRNA body while still allowing a rapid recycling of sRNAs. Furthermore, our model suggests molecular mechanisms for the function of Hfq as an RNA chaperone and for the molecular events that are initiated upon mRNA target recognition.
Domain activities of PapC usher reveal the mechanism of action of an
Escherichia coli
molecular machine
Authors: Volkan Ender , Ford Bradley A. , Pinkner Jerome S. , Dodson Karen W. , Henderson Nadine S. , Thanassi David G. , Waksman Gabriel , Hultgren Scott J.
Published: May 2012

P pili are prototypical chaperone–usher pathway-assembled pili used by Gram-negative bacteria to adhere to host tissues. The PapC usher contains five functional domains: a transmembrane β-barrel, a β-sandwich Plug, an N-terminal (periplasmic) domain (NTD), and two C-terminal (periplasmic) domains, CTD1 and CTD2. Here, we delineated usher domain interactions between themselves and with chaperone–subunit complexes and showed that overexpression of individual usher domains inhibits pilus assembly. Prior work revealed that the Plug domain occludes the pore of the transmembrane domain of a solitary usher, but the chaperone–adhesin-bound usher has its Plug displaced from the pore, adjacent to the NTD. We demonstrate an interaction between the NTD and Plug domains that suggests a biophysical basis for usher gating. Furthermore, we found that the NTD exhibits high-affinity binding to the chaperone–adhesin (PapDG) complex and low-affinity binding to the major tip subunit PapE (PapDE). We also demonstrate that CTD2 binds with lower affinity to all tested chaperone–subunit complexes except for the chaperone–terminator subunit (PapDH) and has a catalytic role in dissociating the NTD–PapDG complex, suggesting an interplay between recruitment to the NTD and transfer to CTD2 during pilus initiation. The Plug domain and the NTD–Plug complex bound all of the chaperone–subunit complexes tested including PapDH, suggesting that the Plug actively recruits chaperone–subunit complexes to the usher and is the sole recruiter of PapDH. Overall, our studies reveal the cooperative, active roles played by periplasmic domains of the usher to initiate, grow, and terminate a prototypical chaperone–usher pathway pilus.
Inhibition of S-phase kinase-associated protein 2 (Skp2) reprograms and converts diabetogenic T cells to Foxp3
+
regulatory T cells
Authors: Wang Ding , Qin Hanjun , Du Weiting , Shen Yueh-Wei , Lee Wen-Hui , Riggs Arthur D. , Liu Chih-Pin
Published: May 2012

Autoreactive pathogenic T cells (Tpaths) and regulatory T cells (Tregs) express a distinct gene profiles; however, the genes and associated genetic/signaling pathways responsible for the functional determination of Tpaths vs. Tregs remain unknown. Here we show that Skp2, an E3 ubiquitin ligase that affects cell cycle control and death, plays a critical role in the function of diabetogenic Tpaths and Tregs. Down-regulation of Skp2 in diabetogenic Tpaths converts them into Foxp3-expressing Tregs. The suppressive function of the Tpath-converted Tregs is dependent on increased production of TGF-β/IL-10, and these Tregs are able to inhibit spontaneous diabetes in NOD mice. Like naturally arising Foxp3
+
nTregs, the converted Tregs are anergic cells with decreased proliferation and activation-induced cell death. Skp2 down-regulation leads to Tpath–Treg conversion due at least in part to up-regulation of several genes involved in cell cycle control and genes in the Foxo family. Down-regulation of the cyclin-dependent kinase inhibitor p27 alone significantly attenuates the effect of Skp2 on Tpaths and reduces the suppressive function of converted Tregs; its effect is further improved with concomitant down-regulation of p21, Foxo1, and Foxo3. In comparison, Skp2 overexpression does not change Tpath function, but significantly decreases Foxp3 expression and abrogates the suppressive function of nTregs. These findings support the critical role of Skp2 in functional specification of Tpaths and Tregs, and demonstrate an important molecular mechanism mediating Skp2 function in balancing immune tolerance during autoimmune disease development.
Bilayer graphene anode for small molecular organic electroluminescence
Authors: Meng H , Dai Y , Ye Y , Luo J X , Shi Z J , Dai L , Qin G G
Published: May 2012

We demonstrate that bilayer graphene can be used as the anode of a small molecule organic light-emitting diode (OLED). In our OLEDs, bilayer graphene was used as the anode, Sm/Au as the cathode and Alq3 as the emitter. By applying Cs2CO3-doped 4,7-diphenyl-1,10-phenanthroline to partly substitute Alq3 as the electron injection and transport layer, the electron current injected from Sm/Au was enhanced to match the hole current injected from the bilayer graphene anode and consequently improved the light emission efficiency. The maxima of luminance efficiency and power efficiency reached 1.18 cd A−1 and 0.41 lm W−1, respectively. We think that the efficiency of the bilayer graphene anode OLED can be further optimized by finding a more efficient electron injection and transport layer and/or reducing the hole density of the graphene anode.
Characteristics of metal-induced crystallization/dopant activation and its application to junction diodes on single-crystalline silicon
Authors: Jung Woo-Shik , Park Jin-Hong , Jung Hyun-Wook , Saraswat Krishna C
Published: May 2012

In this work, we investigated the effect of p- and n-type dopant atoms (boron and phosphorus) on two- and one-step Ni metal-induced crystallization (MIC) of amorphous Si in the aspects of crystallization rate and crystal quality with XRD, SIMS and sheet resistance measurements. The two- and one-step MIC techniques were first applied to fabricate p+/n and n+/p junction diodes on single-crystalline Si substrates below 500 °C and we compared those with the diodes formed by the solid phase crystallization technique at 750 °C, in order to demonstrate the feasibility of the low-temperature MIC junction diodes for source/drain of p- and n-channel single-crystalline Si TFTs.
Microwave excitation of submerged plasma bubbles
Authors: Gidalevich E , Boxman R L
Published: May 2012

Steady-state models were formulated for spherical plasma bubbles, excited in water by an external microwave radiation source. The bubbles were assumed to be at rest relative to the surrounding water, and the energy absorbed by the plasma was balanced by energy loss through thermal conductance and convection to the surrounding water. Two regimes were considered: (1) bubbles with radii R less than the skin depth δ, i.e. R < δ, and (2) bubbles with R > δ. A self-consistent system of equations was formulated. In the R < δ case, a considerable difference was found between electron temperature and the temperature of the heavy plasma components, but this difference decreased with increasing radius. The calculations showed that the bubble radius decreased with increasing electric field amplitude, but R in the R > δ case obtained for strong electric fields was larger than in the R < δ weak field case. The R > δ bubbles had an isothermal core and power from the microwave field was absorbed in a relatively thin layer in the plasma bubble.
Direct observation of keyhole plasma characteristics in deep penetration laser welding of aluminum alloy 6016
Authors: Jin Xiangzhong , Zeng Licheng , Cheng Yuanyong
Published: May 2012

Deep penetration laser welding is associated with violent plasma generation which consists of metal vapour, ionized ions and electrons. The plasma resides both outside and inside the keyhole, known as the plasma plume and keyhole plasma, respectively. Plasma plumes have been studied extensively due to the convenience of observing them. However, very little work has been carried out on the investigation of keyhole plasmas. In this paper, a novel experimental set-up is designed to observe the keyhole plasma directly in CW and PW deep penetration laser welding of aluminum alloy 6016. Then on the basis of the experimentally obtained spectra, the electron temperature distribution of the keyhole plasma both in the radial and depth directions of the keyhole is calculated, and the effects of processing parameters such as laser power, welding velocity and defocus on the keyhole plasma temperature are studied. The results show that the electron temperature of the keyhole plasma both in the radial and depth directions is not uniformly distributed. The temperature increases as the laser power increases, decreases as the welding velocity increases and decreases as the location of the laser beam focal point is moved from within to above the keyhole.
ZnO/Cu2O heterostructure nanopillar arrays: synthesis, structural and optical properties
Authors: Guerguerian Gariné , Elhordoy Fernando , Pereyra Carlos J , Marotti Ricardo E , Martín Francisco , Leinen Dietmar , Ramos-Barrado José R , Dalchiele Enrique A
Published: May 2012

Vertically aligned ZnO/Cu2O heterostructure nanopillar arrays consisting of a ZnO core and a Cu2O shell were fabricated by a two-step electrochemical deposition method. Morphological, structural and optical properties of the nanopillar heterojunctions were investigated. The surface of the single-crystalline ZnO nanopillars was coated uniformly, conformally and densely over the entire nanopillar length by numerous Cu2O nanocrystals (25–35 nm mean diameter), constituting a conformal shell layer 90 nm thick, integrating these two materials into an electronically intimate composite. The optical properties can be interpreted, by appropriate fittings of each feature, as being due to the properties of the bare ZnO nanopillar array plus the increased absorption of Cu2O. This study demonstrates that electrodeposition is a suitable and accessible technique for large-scale fabrication of nanopillar heterostructures and to achieve conformal coverage of nanostructured samples.
Race Composition of Puccinia striiformis f. sp. tritici in Tibet, China
Authors: Hu Xiaoping , Li Jiaojiao , Wang Yating , Wang Baotong , Li Qiang , Kang Zhensheng , Yang Minna , Peng Yueling , Liu Taiguo , Chen Wanquan , Xu Xiangming
Published: May 2012

In Tibet, China, wheat stripe rust (caused by Puccinia striiformis f. sp. tritici) has recently become one of the most destructive diseases on winter wheat. To identify races of the pathogen in Tibet, 261 isolates were obtained in 2010 and tested on seedlings of a standard set of 19 wheat indicator genotypes. Of the 261 isolates, 248 were identified as members of 19 known races (CYR17, CYR20, CYR21, CYR22, CYR23, CYR29, CYR31, CYR32, CYR33, Lov13-6, Su11-1, Su11-2, Su11-3, Su11-4, Su11-5, Su11-6, Su11-7, Su11-8, and Su11-13), and 13 identified as representatives of 4 new races. CYR32 and CYR33 were the most predominant. The number of races and their frequencies in Tibet were more similar to the fungal populations in Sichuan and Gansu provinces than to those in Yunnan, Qinghai, and Shaanxi provinces. The results suggest that Tibet is also a possible center of inoculum source and genetic variation for the stripe rust pathogen in addition to Sichuan and Gansu.
Evaluation of Cultivar Resistance to Soybean Cyst Nematode with a Quantitative Polymerase Chain Reaction Assay
Authors: Lopez-Nicora Horacio D. , Craig James P. , Gao Xuebiao , Lambert Kris N. , Niblack Terry L.
Published: May 2012

Heterodera glycines, the soybean cyst nematode, is a major pathogen of soybean. Effective management of this pathogen is contingent on the use of resistant cultivars; thus, screening for resistant cultivars is essential. The purpose of this research was to develop a method to assess infection of soybean roots by H. glycines with real-time quantitative polymerase chain reaction (qPCR). This method will serve as a prelude to differentiation of resistance levels in soybean cultivars. A reproducible inoculation method was developed by means of a sand column to provide active second-stage juveniles (J2). Two-day-old soybean roots were infested with 0 or 1,000 J2/ml distilled water per seedling. Twenty-four hours after infestation, the roots were surface-sterilized and genomic DNA (gDNA) was extracted. For the qPCR assay, a primer pair for the single copy gene HgSNO, which codes for a protein involved in the production of vitamin B6, was selected for H. glycines gDNA amplification within soybean roots. Compatible ‘Lee 74’, incompatible ‘Peking’, and cultivars with different levels of resistance to H. glycines were infested with 0 or 1,000 J2/ml distilled water per seedling. Twenty-four hours postinfestation, infected seedlings were transplanted into pasteurized soil. Subsequently, they were harvested at 1, 7, 10, 14, and 21 days postinfestation for gDNA extraction. With the qPCR assay, the time needed to differentiate highly resistant cultivars from the rest was reduced. Quantification of H. glycines infection by traditional means (numbers of females produced in 30 days) is a time-consuming practice. This qPCR assay has the potential to replace the traditional Female Index-based screening and improve precision in determining infection levels.
Hot or not? Thermal reactions to social contact
Authors: Hahn Amanda C. , Whitehead Ross D. , Albrecht Marion , Lefevre Carmen E. , Perrett David I.
Published: May 2012

Previous studies using thermal imaging have suggested that face and body temperature increase during periods of sexual arousal. Additionally, facial skin temperature changes are associated with other forms of emotional arousal, including fear and stress. This study investigated whether interpersonal social contact can elicit facial temperature changes. Study 1: infrared images were taken during a standardized interaction with a same- and opposite-sex experimenter using skin contact in a number of potentially high–intimate (face and chest) and low–intimate (arm and palm) locations. Facial skin temperatures significantly increased from baseline during the face and chest contact, and these temperature shifts were larger when contact was made by an opposite-sex experimenter. Study 2: the topography of facial temperature change was investigated in five regions: forehead, periorbital, nose, mouth and cheeks. Increased temperature in the periorbital, nose and mouth regions predicted overall facial temperature shifts to social contact. Our findings demonstrate skin temperature changes are a sensitive index of arousal during interpersonal interactions.
Biologically meaningful coverage indicators for eliminating malaria transmission
Authors: Kiware Samson S. , Chitnis Nakul , Devine Gregor J. , Moore Sarah J. , Majambere Silas , Killeen Gerry F.
Published: May 2012

Mosquitoes, which evade contact with long-lasting insecticidal nets and indoor residual sprays, by feeding outdoors or upon animals, are primary malaria vectors in many tropical countries. They can also dominate residual transmission where high coverage of these front-line vector control measures is achieved. Complementary strategies, which extend insecticide coverage beyond houses and humans, are required to eliminate malaria transmission in most settings. The overwhelming diversity of the world's malaria transmission systems and optimal strategies for controlling them can be simply conceptualized and mapped across two-dimensional scenario space defined by the proportion of blood meals that vectors obtain from humans and the proportion of human exposure to them which occurs indoors.
Three-dimensional cellular structures with negative Poisson's ratio and negative compressibility properties
Authors: Grima Joseph N. , Caruana-Gauci Roberto , Attard Daphne , Gatt Ruben
Published: May 2012

A three-dimensional cellular system that may be made to exhibit some very unusual but highly useful mechanical properties, including negative Poisson's ratio (auxetic), zero Poisson's ratio, negative linear and negative area compressibility, is proposed and discussed. It is shown that such behaviour is scale-independent and may be obtained from particular conformations of this highly versatile system. This model may be used to explain the auxetic behaviour in auxetic foams and in other related cellular systems; such materials are widely known for their superior performance in various practical applications. It may also be used as a blueprint for the design and manufacture of new man-made multifunctional systems, including auxetic and negative compressibility systems, which can be made to have tailor-made mechanical properties.
Kin selection, quorum sensing and virulence in pathogenic bacteria
Authors: Rumbaugh Kendra P. , Trivedi Urvish , Watters Chase , Burton-Chellew Maxwell N. , Diggle Stephen P. , West Stuart A.
Published: May 2012

Bacterial growth and virulence often depends upon the cooperative release of extracellular factors excreted in response to quorum sensing (QS). We carried out an
in vivo
selection experiment in mice to examine how QS evolves in response to variation in relatedness (strain diversity), and the consequences for virulence. We started our experiment with two bacterial strains: a wild-type that both produces and responds to QS signal molecules, and a
lasR
(signal-blind) mutant that does not release extracellular factors in response to signal. We found that: (i) QS leads to greater growth within hosts; (ii) high relatedness favours the QS wild-type; and (iii) low relatedness favours the
lasR
mutant. Relatedness matters in our experiment because, at relatively low relatedness, the
lasR
mutant is able to exploit the extracellular factors produced by the cells that respond to QS, and hence increase in frequency. Furthermore, our results suggest that because a higher relatedness favours cooperative QS, and hence leads to higher growth, this will also lead to a higher virulence, giving a relationship between relatedness and virulence that is in the opposite direction to that usually predicted by virulence theory.
Dibenzylazanium (oxalato-κ2
O,O′)triphenylstannate(IV)
Authors: Gueye Ndongo , Diop Libasse , Molloy Kieran C. , Kociok-Köhn Gabrielle
Published: May 2012

The title compound, (C14H16N)[Sn(C6H5)3(C2O2)], was synthesised by allowing C2O4(Bz2NH2)2 (Bz = benzyl) to react with SnPh3Cl. The asymmetric unit is built up by four SnPh3C2O4 anions and four Bz2NH2 cations which are related by a pseudo-inversion centre. Each SnIV cation is five-coordinated by the three phenyl groups and two O atoms belonging to the chelating oxalate ligand; the coordination geometry is that of a distorted trigonal bipyramid. Anions and cations are linked through N—H...O hydrogen bonds into a layer structure parallel to (001). Moreover, the anion–cation pairs are associated by two bifurcated N—H...O hydrogen bonds, generating pseudo-dimers. One of the phenyl groups of one anion is disordered over two sets of sites in a 0.69:0.31 ratio. The Flack parameter value of 0.44 (1) indicates racemic twinning.
Methyl 3-aminobut-2-enoate
Authors: Wang Xiao , Zhang Li-Zhu
Published: May 2012

The title compound, C5H9NO2, is almost planar (r.m.s. deviation for the non-H atoms = 0.036 Å) and an intramolecular N—H...O hydrogen bond generates an S(6) ring. In the crystal, N—H...O interactions link the molecules into C(6) chains propagating along [010].
1-Ethyl-4-[1-(1-phenylethylidene)hydrazin-2-ylidene]-3,4-dihydro-1H-2λ6,1-benzothiazine-2,2-dione
Authors: Shafiq Muhammad , Khan Islam Ullah , Arshad Muhammad Nadeem , Bukhari Iftikhar Hussain , Ejaz
Published: May 2012

In the title compound, C18H19N3O2S, the thiazine ring adopts an envelope conformation, with the S atom displaced by 0.732 (1) Å from the other atoms of the ring. The phenyl ring is oriented at a dihedral angle of 79.33 (7)° with respect to the fused benzene ring. The conformations about the two double bonds in the R
2C=N—N=C(CH3)Ar grouping are Z and E, respectively. In the crystal, inversion dimers linked by pairs of C—H...O interactions generate R
2
2(8) and R
2
2(12) loops, as parts of infinite chains along the a-axis direction.
2-Amino-4-(4-fluorophenyl)-6-methoxy-4H-benzo[h]chromene-3-carbonitrile
Authors: Al-Dies Al-Anood M. , Amr Abdel-Galil E. , El-Agrody Ahmed M. , Chia Tze Shyang , Fun Hoong-Kun
Published: May 2012

In the title molecule, C21H15FN2O2, the dihedral angle between the fluoro-substituted benzene ring and the mean plane of the 4H-benzo[h]chromene ring system [maximum deviation = 0.109 (2) Å] is 83.35 (7)°. The pyran ring adopts a slight sofa conformation with the tertiary C(H) atom forming the flap. The methoxy group is slightly twisted from the attached benzene ring of the 4H-benzo[h]chromene moiety [C—O—C—C = −4.3 (3)°]. In the crystal, molecules are linked by intermolecular N—H...N hydrogen bonds into infinite wave-like chains along the b axis. The crystal packing is further stabilized by π–π interactions [centroid–centroid distance = 3.7713 (9) Å].
Poly[diaqua(μ5-pyridine-3,5-dicarboxylato)strontium]
Authors: Li Dan , Duan Chaowen
Published: May 2012

In the structure of the title compound, [Sr(C7H3NO4)(H2O)2]
n
, the SrII cation is eight-coordinated in form of a distorted dodecahedron by two water O atoms and by five O atoms and one N atom from five pyridine-3,5-dicarboxylate anions. The bridging mode of the anions leads to the formation of a layered network parallel to (100). O—H...O hydrogen bonding between the coordinating water molecules and the carboxylate groups of adjacent layers consolidates the crystal packing. Weak C—H...O interactions are also observed.
3-O-Methyl-1-isomangostin
Authors: Boonnak Nawong , Chantrapromma Suchada , Fun Hoong-Kun
Published: May 2012

In the title xanthone derivative [systematic name: 9-hydroxy-5,10-dimethoxy-2,2-dimethyl-11-(3-methylbut-2-en-1-yl)-2,3,4,12-tetrahydro-1,7-dioxatetraphen-12-one], C25H28O6, the xanthone ring system is roughly planar, with an r.m.s. deviation of 0.1038 (1) Å. The chromane ring is in a half-chair conformation and the 3-methylbut-2-enyl substituent is axially attached with an (+)-anticlinal conformation. Two weak intramolecular C—H...O interactions generate two S(6) ring motifs. In the crystal, molecules are linked into ribbons along the c axis by O—H...O and weak C—H...O hydrogen bonds. A π–π interaction, with a centroid–centroid distance of 3.5413 (8) Å, is also observed.
2-(2-Hydroxy-3-methoxyphenyl)-1H-benzimidazol-3-ium perchlorate
Authors: Chen Chuan , Li Hong-Xing , Hou Guang-Feng , Li Guang-Ming
Published: May 2012

In the title molecular salt, C14H13N2O2
+·ClO4
−, the ring systems in the cation are almost coplanar [dihedral angle = 5.53 (13)°]. Intramolecular N—H...O and O—H...O hydrogen bonds generate S(6) and S(5) rings, respectively. In the crystal, the two H atoms involved in the intramolecular hydrogen bonds also participate in intermolecular links to acceptor O atoms of the perchlorate anions. A simple intermolecular N—H...O bond also occurs. Together, these form a double-chain structure along [101].
1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-aminium bromide monohydrate
Authors: Yang Yan-Yun , Xu Liang , Kang Ting-Guo , Chen Ting , Wu Ping
Published: May 2012

In the title hydrated molecular salt, C11H14N3O+·Br−·H2O, the Br− anion is split and appears as two independent half-occupied Br− anions on twofold rotation axes. The dihedral angle between the phenyl ring and the mean plane of the 2,3-dihydro-1H-pyrazole ring (r.m.s. devation = 0.014 Å) is 62.43 (7)°. In the crystal, the components are connected via O—H...Br and N—H...O hydrogen bonds to form a one-dimensional polymeric structure propagating along [001].
L-Alanylglycylhistamine dihydrochloride
Authors: Selmeczi Katalin , Gizzi Patrick , Wenger Emmanuel , Henry Bernard
Published: May 2012

In the title compound {systematic name: 4-[2-({N-[(2S)-2-ammoniopropanoyl]glycyl}amino)ethyl]-1H-imidazol-3-ium dichloride}, C10H19N5O2
2+·2Cl−, the pseudo-tripeptide L-alanylglycylhistamine is protonated at both the terminal amino group and the histidine N2 atom. The resulting positive charges are neutralized by two chloride anions. In the crystal, the organic cation adopts a twisted conformation about the CH2—CH2 bond of histamine and about the C—N bond in the main chain, stabilized by a short intramolecular C—H...O contact. In the crystal, N+—H...O and N+—H...Cl− hydrogen bonds link the molecules into infinite sheets parallel to the (100) plane. The stacking of these sheets along the a axis is supported by Namide—H...Cl− hydrogen bonds.
4-Hydroxyanilinium 2-carboxyacetate
Authors: Wang Ying-Chun
Published: May 2012

In the title compound, C6H8NO+·C3H3O4
−, the amino N atom is protonated, and one of the carboxyl groups is deprotonated to maintain the charge balance. In the crystal, classical N—H...O and O—H...O hydrogen bonds connect the ions into a two-dimensional network parallel to the ac plane. In addition, the structure is further stabilized by C—H...O and π–π interactions [centroid–centroid distance = 4.115 (2) Å].
2-{2-[4-(Dimethylamino)phenyl]diazen-1-ium-1-yl}pyridinium tetrachloridozincate
Authors: Leesakul Nararak , Runrueng Wassana , Saithong Saowanit , Pakawatchai Chaveng
Published: May 2012

The title compound, (C13H16N4)[ZnCl4], consists of a tetrahedral [ZnCl4]2− anion and a 2-{2-[4-(dimethylamino)phenyl]diazen-1-ium-1-yl}pyridinium dication. The pyridinium-N atom is syn to the azo bond which allows for the formation of an intramolecular N—H...N hydrogen bond. In the crystal, the cation and anion are held together by N—H...Cl hydrogen-bond interactions involving the pyridinium and diazen-1-ium N atoms. π–π stacking interactions occur between the pyridine and benzene rings of adjacent cations [centroid–centroid distances = 3.6270 (18) and 3.8685 (18) Å]; the stacks are parallel to the a axis.
Poly[bis(μ7-3-sulfonato-L-alaninato)sodiumzinc]
Authors: Li Xiao-lin , Yu Jing , Liu Li
Published: May 2012

The hydrothermal reaction of Zn(CH3COO)2, NaOH and L-cysteic acid produced the title compound, [Na2Zn(C3H5NO5S)2]
n
. The ZnII cation is situated on an inversion centre and is in a distorted octahedral environment, being chelated by two deprotoned L-cysteic acid ligands through two amino N atoms and two carboxylic O atoms, with the two axial positions occupied by two carboxylic O atoms from two other L-cysteic acid ligands. Each L-cysteic acid ligand bridges five NaI ions via its sulfonate group and two ZnII ions via its carboxyl group, forming a three-dimensional framework. Weak N—H...O hydrogen bonding is observed in the crystal structure.
KMg0.09Fe1.91(PO4)2
Authors: Yatskin Michael M. , Zatovsky Igor V. , Baumer Vyacheslav N. , Ogorodnyk Ivan V. , Slobodyanik Nikolay S.
Published: May 2012

KMg0.09Fe1.91(PO4)2, potassium [iron(II)/magnesium] iron(III) bis(orthophosphate), is a solid solution derived from compounds with general formula KM
IIFe(PO4)2 (M
II = Fe, Cu), in which the Mg atoms substitute Fe atoms only in the octahedrally surrounded sites. The framework of the structure is built up from [FeO5] trigonal bipyramids and [MO6] (M = (Fe, Mg) octahedra sharing corners and edges and connected by two types of bridging PO4 tetrahedra. The K+ cations are nine-coordinated and are situated in channels running along [101].
4-{1-[4-(4-Bromophenyl)-1,3-thiazol-2-yl]-5-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-3-yl}-5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazole
Authors: Abdel-Wahab Bakr F. , Mohamed Hanan A. , Ng Seik Weng , Tiekink Edward R. T.
Published: May 2012

In the title compound, C28H22BrFN6S, the central pyrazole ring has an envelope conformation, with the methine C atom being the flap atom. The dihedral angles between the least-squares plane through this ring and the adjacent thiazole [18.81 (15)°] and triazole [1.83 (16)°] rings indicate a twist in the molecule. A further twist is evident by the dihedral angle of 64.48 (16)° between the triazole ring and the attached benzene ring. In the crystal, C—H...N, C—H...F, C—H...π and π–π interactions [occurring between the thiazole and triazole rings, centroid–centroid distance = 3.571 (2) Å] link molecules into a three-dimensional architecture. The sample studied was a non-merohedral twin; the minor twin component refined to 47.16 (7)%.
N-(4-Methylphenyl)formamide
Authors: Zhao Min-Min
Published: May 2012

In the title compound, C8H9NO, the amide group makes a dihedral of 32.35 (1)° with the benzene ring. In the crystal, pairs of strong N—H...O hydrogen bonds link the molecules into inversion dimers. Weak C—H...O interactions further connect the molecules into chains along the a axis.
(E)-3-(4-Cyclohexyl-3-fluorobenzylidene)chroman-4-one
Authors: Gopaul Kaalin , Shaikh Mahidansha M. , Koorbanally Neil A. , Ramjugernath Deresh , Omondi Bernard
Published: May 2012

The title compound, C22H21FO2, exhibits substitutional disorder of the F atom and a H atom in the asymmetric unit with different occupancies, the refined F:H ratio being 0.80 (2):0.20 (2). The dihedral angle between the fluorinated benzene ring and the benzene ring of the chromanone system is 37.30°. There are two relatively high residual electron-density peaks associated with the disorder.
Relationship between body size and habitat complexity preference in age‐0 and ‐1 year winter flounder Pseudopleuronectes americanus
Authors: Pappal A. L. , Rountree R. A. , MacDonald D. G.
Published: May 2012

The interaction between body size, habitat complexity and interstice width on habitat preference of age‐0 and ‐1 year Pseudopleuronectes americanus was examined using continuous remote video observation. The habitat choices of juvenile P. americanus were recorded over a 6 h period in tanks with four treatments: bare sand, sand with low complexity cobble, sand with intermediate complexity cobble and sand with high complexity cobble. Both age‐0 and ‐1 year fish preferred cobble to bare sand. Within cobble treatments, age‐0 year fish preferred intermediate complexity cobble, with a 1·59 ratio of interstitial space to body width. The largest age‐1 year fish (123–130 mm standard length, LS) preferred low complexity cobble. While a significant preference was not detected, medium age‐1 year fish (83–88 mm LS) tended to select low complexity cobble, whereas small age‐1 year fish (73–82 mm LS) tended to select low and intermediate cobble, with an interstitial space to body width ratio of 1·05. For medium and large age‐1 year fish, there was an increased selection of low complexity cobble, corresponding to larger interstitial space to body size ratios. This study indicates that juvenile P. americanus prefer complex habitat to unstructured habitat and that this preference is mediated by a relationship between fish body size and the size of structure interstices. These results contribute to the growing body of knowledge of complex habitat selection and drivers of habitat choice in flatfishes.
Therapeutic upregulation of Class A scavenger receptor member 5 inhibits tumor growth and metastasis
Authors: Yan Nv , Zhang Shuang , Yang Yang , Cheng Lin , Li Can , Dai Lixia , Dai Lei , Zhang Xiaomei , Fan Ping , Tian Hongwei , Wang Ruibo , Chen Xiaolei , Su Xiaolan , Li Yiming , Zhang Junfeng , Du Tao , Wei Yuquan , Deng Hongxin
Published: May 2012

Class A scavenger receptor member 5 (SCARA5) is a new member of the Class A scavenger receptors that has been proposed recently as a novel candidate tumor suppressor gene in human hepatocellular carcinoma. In the present study, we found that SCARA5 expression was frequently downregulated in various cancer cell lines and tumor samples. In addition, upregulation of SCARA5 expression in human cancer cell line (U251) led to a significant decrease in cell proliferation, clone formation, migration, and invasion in vitro. Furthermore, systemic treatment of tumor‐bearing mice with SCARA5–cationic liposome complex not only reduced the growth of subcutaneous human glioma tumors, but also markedly suppressed the spontaneous formation of lung metastases. Similar results were obtained in another experiment using mice bearing experimental A549 lung metastases. Compared with the untreated control group, mice treated with SCARA5 exhibited reductions in both spontaneous U251 and experimental A549 lung metastases rates of 77.3% and 70.2%, respectively. Western blot analysis was used to explore the molecular mechanisms involved and revealed that SCARA5 physically associated with focal adhesion kinase. Interestingly, upregulation of SCARA5 inactivated signal transducer and activator of transcription 3, as well as downstream signaling including cyclinB1, cyclinD1, AKT, survivin, matrix metalloproteinase‐9 and vascular endothelial growth factor‐A. Overall, the findings of the present study provide the first evidence that SCARA5 might be a promising target for the development of new antimetastatic agents for the gene therapy of cancer.
Alcohol licensing in Scotland: a historical overview
Authors: Nicholls James
Published: May 2012

Aim  This paper provides a historical overview of licensing law in Scotland. It seeks to put important contemporary policy developments into their historical context and to draw attention to key themes in licensing policy debates across the United Kingdom.

Design  Based on a survey of statutes, commissions of enquiry and consumption and retail data, this paper draws together historical evidence to present a synopsis of Scottish licensing history.

Settings  The article focuses on Scotland, but also discusses UK‐wide licensing policy over a 250‐year period.

Findings  Scottish licensing has diverged from licensing in England and Wales and has addressed some historical licensing weaknesses, including problems of accountability, overprovision and systemic oversight regarding off‐sales. Distinctive features of current Scottish legislation include public health protection as a statutory licensing objective; local Licensing Forums and Licensing Standards Officers; a requirement for explicit policies on the ‘overprovision’ of licensed premises; mandatory restrictions on price promotions in the on‐ and off‐trades; and limitations on opening hours for off‐licences.

Conclusion  Scotland has developed alcohol policies several times addressing long‐standing licensing weaknesses throughout the United Kingdom. Some Scottish alcohol policies have later become the norm in England and Wales.
Endogenous oestradiol as a positive correlate of plasma fibrinogen among older postmenopausal women: a population‐based study (the Three‐City cohort study)
Authors: Canonico Marianne , Brailly‐Tabard Sylvie , Gaussem Pascale , Setiao Julie , Rouaud Olivier , Ryan Joanne , Carcaillon Laure , Guiochon‐Mantel Anne , Scarabin Pierre‐Yves
Published: May 2012

Background

Plasma fibrinogen is a strong predictor of ischaemic arterial disease in women. Sex steroid hormones including hormone therapy may play an important role in the development of cardiovascular disease. However, whether endogenous sex steroid hormones influence the plasma fibrinogen concentrations among postmenopausal women remains unclear.

Objectives

To investigate the association of plasma fibrinogen levels with endogenous sex steroid hormones and sex hormone binding globulin (SHBG) among postmenopausal women.

Methods

We used data from the French prospective Three‐City cohort study that included 9294 noninstitutionalized men and women over 65 years of age. Total 17β‐oestradiol (E2, pg/ml), total testosterone (T, ng/ml), SHBG (nm) and fibrinogen (g/l) were measured in stored plasmas in a subcohort of 602 randomly selected postmenopausal women who used neither hormone medication nor anticoagulation therapy. Multivariate linear regression models were used to estimate the regression coefficients assessed in fibrinogen unit by 1 SD increase in log‐distribution of sex steroid hormones and SHBG.

Results

E2 but neither T nor SHBG was positively associated with plasma fibrinogen levels (β = 0·148, P < 0·001). Adjustment for cardiovascular risk factors including diabetes made no substantial change to the results (β = 0·145, P < 0·001). The association of fibrinogen with E2 was stronger among women with body mass index over 25 kg/m2 compared with those with normal weight (β = 0·156, P < 0·001 and β = 0·092, P = 0·02, respectively, P for interaction = 0·04).

Conclusion

E2 emerges as a positive and independent correlate of plasma fibrinogen among postmenopausal women, especially in subjects who are overweight. These findings suggest a deleterious effect of endogenous oestrogens on cardiovascular risk profile among postmenopausal women.