bluuebunny/crossref_metadata_2025 huggingface dataset:
Medical Care at Mass Gatherings: Emergency Medical Services at Large-Scale Rave Events
Authors: Krul Jan , Sanou Björn , Swart Eleonara L , Girbes Armand R J
Published: April 2012

Objective: The objective of this study was to develop comprehensive guidelines for medical care during mass gatherings based on the experience of providing medical support during rave parties.

Methods: Study design was a prospective, observational study of self-referred patients who reported to First Aid Stations (FASs) during Dutch rave parties. All users of medical care were registered on an existing standard questionnaire. Health problems were categorized as medical, trauma, psychological, or miscellaneous. Severity was assessed based on the Emergency Severity Index. Qualified nurses, paramedics, and doctors conducted the study after training in the use of the study questionnaire. Total number of visitors was reported by type of event.

Results: During the 2006–2010 study period, 7,089 persons presented to FASs for medical aid during rave parties. Most of the problems (91.1%) were categorized as medical or trauma, and classified as mild. The most common medical complaints were general unwell-being, nausea, dizziness, and vomiting. Contusions, strains and sprains, wounds, lacerations, and blisters were the most common traumas. A small portion (2.4%) of the emergency aid was classified as moderate (professional medical care required), including two cases (0.03%) that were considered life-threatening. Hospital admission occurred in 2.2% of the patients. Fewer than half of all patients presenting for aid were transported by ambulance. More than a quarter of all cases (27.4%) were related to recreational drugs.

Conclusions: During a five-year field research period at rave dance parties, most presentations on-site for medical evaluation were for mild conditions. A medical team of six healthcare workers for every 10,000 rave party visitors is recommended. On-site medical staff should consist primarily of first aid providers, along with nurses who have event-specific training on advanced life support, event-specific injuries and incidents, health education related to self-care deficits, interventions for psychological distress, infection control, and disaster medicine. Protocols should be available for treating common injuries and other minor medical problems, and for registration, triage, environmental surveillance and catastrophe management and response.
Association between body composition and conformity to the recommendations of Canada's Food Guide and the Dietary Approaches to Stop Hypertension (DASH) diet in peri-adolescence
Authors: Hajna Samantha , Liu Jian , LeBlanc Paul J , Faught Brent E , Merchant Anwar T , Cairney John , Hay John
Published: April 2012

Objective

The role of following the recommendations of Canada's Food Guide (CFG) and the Dietary Approaches to Stop Hypertension (DASH) diet on body composition in children is unknown. The present study assessed how conformity to the recommendations of these diets was associated with BMI, waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), waist girth (WG), hip girth (HG) and risk of overweight in peri-adolescents.

Design

CFG and DASH indices were derived from responses to a food questionnaire, with a higher index representing greater conformity to CFG and DASH diet recommendations. Body composition was assessed by trained research assistants.

Setting

Schools within the Niagara region (Ontario, Canada).

Subjects

Children (n 1570) aged 12·4 (sd 0·3) years.

Results

After adjustment for age to peak height velocity and total physical activity, a higher CFG index was associated with lower WHtR (b = −0·001, 95 % CI −0·002, −0·0004), WHR (b = −0·001, 95 % CI −0·002, −0·001) and WG (b = −0·18, 95 % CI −0·30, −0·07) in girls. No associations were observed in boys. In contrast, a higher DASH index was associated with decreased body composition measures in both genders. Specifically, the DASH index was negatively associated with BMI (girls: b = −0·07, 95 % CI −0·10, −0·04; boys: b = −0·05, 95 % CI −0·08, −0·02), WHtR (girls: b = −0·001, 95 % CI −0·002, −0·001; boys: b = −0·001, 95 % CI −0·002, −0·0004), WHR (girls: b = −0·001, 95 % CI −0·002, −0·001; boys: b = −0·001, 95 % CI −0·001, −0·00004), WG (girls: b = −0·24, 95 % CI −0·31, −0·16; boys: b = −0·15, 95 % CI −0·24, −0·07) and HG (girls: b = −0·15, 95 % CI −0·23, −0·07; boys: b = −0·12, 95 % CI −0·19, −0·04). A higher DASH index was also associated with lower odds of overweight in girls (OR = 0·70, 95 % CI 0·56, 0·87) and boys (OR = 0·76, 95 % CI 0·62, 0·93).

Conclusions

The DASH diet may prevent overweight in peri-adolescents.
Electrophysiological and neurochemical effects of long-term vagus nerve stimulation on the rat monoaminergic systems
Authors: Manta Stella , El Mansari Mostafa , Debonnel Guy , Blier Pierre
Published: April 2012

Vagus nerve stimulation (VNS) is an adjunctive treatment for resistant epilepsy and depression. Electrophysiological recordings in the rat brain have already shown that chronic VNS increases norepinephrine (NE) neuronal firing activity and, subsequently, that of serotonin (5-HT) neurons through an activation of their excitatory α1-adrenoceptors. Long-term VNS was shown to increase the tonic activation of post-synaptic 5-HT1A receptors in the hippocampus. This study was aimed at examining the effect of VNS on extracellular 5-HT, NE and dopamine (DA) levels in different brain areas using in vivo microdialysis, on NE transmission in the hippocampus, and DA neuronal firing activity using electrophysiology. Rats were implanted with a VNS device and stimulated for 14 d with standard parameters used in treatment-resistant depression (0.25 mA, 20 Hz, 500 µs, 30 s on–5 min off). The results of the present study revealed that 2-wk VNS significantly increased extracellular NE levels in the prefrontal cortex and the hippocampus and enhanced the tonic activation of post-synaptic α2-adrenoceptors on pyramidal neurons. The electrophysiological experiments revealed a significant decrease in ventral tegmental area DA neuronal firing rate after long-term VNS; extracellular DA levels were nevertheless increased in the prefrontal cortex and nucleus accumbens. Chronic VNS significantly increased extracellular 5-HT levels in the dorsal raphe but not in the hippocampus and prefrontal cortex. In conclusion, the effect of VNS in increasing the transmission of monoaminergic systems targeted in the treatment of resistant depression should be involved, at least in part, in its antidepressant properties observed in patients not responding to many antidepressant strategies.
Modeling the ENSO impact of orbitally induced mean state climate changes
Authors: Salau O. R. , Schneider B. , Park W. , Khon V. , Latif M.
Published: April 2012

The sensitivity of the El Niño–Southern Oscillation (ENSO) phenomenon to changes in the tropical Pacific mean climate is investigated with a coupled atmosphere‐ocean‐sea ice general circulation model (AOGCM), the Kiel Climate Model (KCM). Different mean climate states are generated by changing the orbital forcing that causes a redistribution of solar energy, which was a major driver of both the Holocene and the Eemian climates. We find that the ENSO amplitude is positively correlated with both the Equatorial Pacific sea surface temperature (SST) and the equatorial zonal SST contrast. The latter is controlled by the upwelling‐induced damping of the SST changes in the Eastern Equatorial Pacific (EEP), and by the vertical ocean dynamical heating and zonal heat transport convergence in the Western Equatorial Pacific. The ENSO amplitude also correlates positively with the seasonal SST amplitude in the EEP and negatively with the strength of the easterly Trades over the Equatorial Pacific. However, the ENSO period is rather stable and stays within 3–4 years. Enhanced ENSO amplitude is simulated during the late‐Holocene, in agreement with paleoproxy records. The tight positive correlation (r = 0.89) between the ENSO strength and the Western Pacific Warm Pool (WPWP) SST suggests that the latter may provide an indirect measure of the ENSO amplitude from proxy data that cannot explicitly resolve interannual variability.
Development of a soil moisture analysis for subseasonal forecasting: Soil moisture validation
Authors: Boisserie M. , Cocke S.
Published: April 2012

The goal of this study is to produce a new soil moisture analysis for subseasonal forecasting. An accurate soil moisture initialization is today widely recognized as having a great potential to increase summertime subseasonal forecasting skill. In this study, soil moisture initial conditions are generated using the Precipitation Assimilation Reanalysis (PAR) technique. This technique consists mainly of nudging precipitation in a coupled land‐atmosphere model by adjusting the vertical air humidity profile based on the difference between model and observed precipitation rates in a continuous assimilation period of a few months. The effect of the PAR technique on the model soil moisture estimates is evaluated using (1) a benchmark in global soil moisture analysis produced by the Global Soil Wetness Project Phase 2 (GSWP‐2) and (2) in‐situ observations from the state of Illinois. Using PAR, we find that the coupled land‐atmosphere FSU/COAPS model reproduces with a reasonable accuracy the seasonal cycle and the temporal variability of monthly soil moisture anomalies produced by GSWP‐2 across most of the globe. The temporal structure of monthly soil moisture anomalies match also fairly well with in‐situ observations from the Illinois state deep into the soil. Finally, overall the PAR technique shows better results than the NCEP/DOE Reanalysis 2. Therefore, in this study we have developed a new soil moisture analysis product that (1) is physically consistent with the atmospheric physics of the coupled land‐atmosphere FSU/COAPS model, (2) is globally comparable with GSWP‐2 and (3) better fits in‐situ observed soil moisture characteristics than R2 over Illinois.
Magnetic and seismic reflection study of Lake Cheko, a possible impact crater for the 1908 Tunguska Event
Authors: Gasperini L. , Cocchi L. , Stanghellini C. , Stanghellini G. , Del Bianco F. , Serrazanetti M. , Carmisciano C.
Published: April 2012

A major explosion occurred on 30 June 1908 in the Tunguska region of Siberia, causing the destruction of over 2,000 km2 of taiga; pressure and seismic waves detected as far as 1,000 km away; bright luminescence in the night skies of Northern Europe and Central Asia; and other unusual phenomena. This “Tunguska Event” is probably related to the impact with the Earth of a cosmic body that exploded about 5–10 km above ground, releasing in the atmosphere 10–15 Mton of energy. Fragments of the impacting body have never been found, and its nature (comet or asteroid) is still a matter of debate. We report here results from a magnetic and seismic reflection study of a small (∼500 m diameter) lake, Lake Cheko, located about 8 km NW of the inferred explosion epicenter, that was proposed to be an impact crater left by a fragment of the Tunguska Cosmic Body. Seismic reflection and magnetic data revealed a P wave velocity/magnetic anomaly close to the lake center, about 10 m below the lake floor; this anomaly is compatible with the presence of a buried stony object and supports the impact crater origin for Lake Cheko.
A new mechanism for the generation of quasi‐zonal jets in the ocean
Authors: Wang Jinbo , Spall Michael A. , Flierl Glenn R. , Malanotte‐Rizzoli Paola
Published: April 2012

A simple barotropic quasi‐geostrophic model is used to demonstrate that instabilities radiated from an unstable eastern boundary current can generate zonal striations in the ocean interior with realistic wavelengths and amplitudes. Nonlinear transfer of energy from the more unstable trapped modes is important for radiating modes to overcome friction. The dynamics shown here are generic enough to point to the eastern boundary current as a likely source of the observed striations extending from oceanic eastern boundaries.
Modeling the effects of silica deposition and fault rupture on natural geothermal systems
Authors: Dempsey D. E. , Rowland J. V. , Zyvoloski G. A. , Archer R. A.
Published: April 2012

Natural geothermal convection abounds within the Taupo Volcanic Zone (TVZ) of New Zealand's Central North Island. In many locations the highly porous eruptive products that blanket the landscape have been altered by the throughput of hydrothermal fluids and the consequent deposition of silica. We detail a numerical model that considers the evolution of a geothermal plume in the presence of silica deposition/dissolution that controls an evolving permeability distribution. Precipitation of silica occurs according to a gradient reaction regime, in which the dissolved silica concentration is controlled by the temperature dependent silica solubility. Over a period of 120 kyr, continuous geothermal circulation leads to the development of a low permeability cap‐zone, approximately 200 m thick, above the main geothermal upflow zone. The cap‐zone encourages lateral flow of rising fluids, increasing the area across which geothermal expression is observed. It also has an insulating effect on fluids below the cap, causing increases in temperature, enthalpy, and the reservoir potential of the field. A second model is constructed to consider the specific scenario of fault rupture through the impermeable cap‐zone. Coseismic increases in permeability along the fault plane produce vigorous, renewed flow through the center of the geothermal field, temporarily reducing lateral flows. However, resealing of near surface permeability is rapid, and the restoration of lateral flows and recovery of the geothermal reservoir occurs within ∼10 kyr. These effects are discussed in the context of two TVZ geothermal fields: the extinct Ohakuri field, and Te Kopia, which is situated on a major active normal fault.
Annual variability in a conceptual climate model: Snapshot attractors, hysteresis in extreme events, and climate sensitivity
Authors: Bódai Tamás , Tél Tamás
Published: April 2012

In a conceptual model of global atmospheric circulation, the effects of annually periodic driving are investigated. The driven system is represented in terms of snapshot attractors, which may remain fractal at all times. This is due to the transiently chaotic behavior in the regular parameter regimes of the undriven system. The driving with annual periodicity is found to be relatively fast: There is a considerable deviation from the undriven case. Accordingly, the existence of a hysteresis loop is identified, namely, the extremal values of a given variable depend not only on the actual strength of the insolation but also on the sign of its temporal change. This hysteresis is due to a kind of internal memory. In the threshold-dependence of mean return times of various extreme events, a roughly exponential scaling is found. Climate sensitivity parameters are defined, and the measure of certain types of extremal behavior is found to be strongly susceptible to changes in insolation.
Switching through intermediate states seen in a single nickel nanorod by cantilever magnetometry
Authors: Lee SangGap , Moore Eric W. , Hickman Steven A. , Longenecker Jonilyn G. , Marohn John A.
Published: April 2012

In-plane to out-of-plane magnetization switching in a single nickel nanorod affixed to an attonewton-sensitivity cantilever was studied at cryogenic temperatures. We observe multiple sharp, simultaneous transitions in cantilever frequency, dissipation, and frequency jitter associated with magnetic switching through distinct intermediate states. These findings suggest a new route for detecting magnetic fields at the nanoscale.
Interfacial and coexistence properties of soft spheres with a short-range attractive Yukawa fluid: Molecular dynamics simulations
Authors: González-Melchor Minerva , Hernández-Cocoletzi Gregorio , López-Lemus Jorge , Ortega-Rodríguez Alejandro , Orea Pedro
Published: April 2012

Molecular dynamics simulations have been carried out to obtain the interfacial and coexistence properties of soft-sphere attractive Yukawa (SAY) fluids with short attraction range, κ = 10, 9, 8, 7, 6, and 5. All our simulation results are new. These data are also compared with the recently reported results in the literature of hard-core attractive Yukawa (HAY) fluids. We show that the interfacial and coexistence properties of both potentials are different. For the surveyed systems, here we show that all coexistence curves collapse into a master curve when we rescale with their respective critical points and the surface tension curves form a single master curve when we plot γ* vs. T/Tc.
Temperature dependence of the electron spin g factor in CdTe and InP
Authors: Pfeffer Pawel , Zawadzki Wlodek
Published: April 2012

Temperature dependence of the electron spin g factors in bulk CdTe and InP is calculated and compared with experiment. It is assumed that the only modification of the band structure related to temperature is a dilatation change in the fundamental energy gap. The dilatation changes of fundamental gaps are calculated for both materials using available experimental data. Computations of the band structures in the presence of a magnetic field are carried out employing five-level P·p model appropriate for medium-gap semiconductors. In particular, the model takes into account spin splitting due to bulk inversion asymmetry (BIA) of the materials. The resulting theoretical effective masses and g factors increase with electron energy due to band nonparabolicity. Average g values are calculated by summing over populated Landau and spin levels properly accounting for the thermal distribution of electrons in the band. It is shown that the spin splitting due to BIA in the presence of a magnetic field gives observable contributions to g values. Our calculations are in good agreement with experiments in the temperature range of 0 K to 300 K for CdTe and 0 K to 180 K for InP. The temperature dependence of g is stronger in CdTe than in InP due to different signs of band-edge g values in the two materials. Good agreement between the theory and experiments strongly indicates that the temperature dependence of spin g factors is correctly explained. In addition, we discuss formulas for the energy dependence of spin g factor due to band nonparabolicity, which are liable to misinterpretation.
Optically controlled spin-dependent Andreev reflection and spin accumulation in a quantum dot
Authors: Pan Hui , Lü Rong
Published: April 2012

We theoretically investigate the Andreev reflection and the spin accumulation in a quantum dot subjected to a continuous circularly polarized optical irradiation. Due to the optical pumping effects, electrons having a certain spin experience the Rabi oscillation and their energy levels are shifted by the Rabi frequency. Correspondingly, only electrons with certain spin can contribute to the current by adjusting the dot level and the bias voltage. The Andreev reflection current thus becomes spin dependent and exhibits a tunable spin polarization. Furthermore, the electron occupation number in the quantum dot also becomes spin dependent and exhibits a strong spin accumulation. The magnitude and direction of the spin accumulation in the quantum dot can be easily controlled by tuning the dot level and the bias voltage. This provides an efficient mechanism to control the Andreev reflection and spin accumulation in the quantum dot.
Growth of triangle-shape graphene on Cu(111) surface
Authors: Chen Xiu , Liu Shuyi , Liu Lacheng , Liu Xiaoqing , Liu Xiaoming , Wang Li
Published: April 2012

Triangle-shape graphene has been grown on Cu(111) surface by thermal decomposition of 1,1′-ferrocenedicarboxylic acid molecules in an ultrahigh vacuum chamber. The observations of Moiré patterns and honeycomb structure unambiguously reveal that such triangle-shape graphene is a single-crystalline one-layer domain with zigzag edge structure. Graphene islands can extend up to 17 nm until the growth process is hindered by the edges of the atomic terraces.
Strategies for tuning phonon transport in multilayered structures using a mismatch-based particle model
Authors: Le Nam Q. , Duda John C. , English Timothy S. , Hopkins Patrick E. , Beechem Thomas E. , Norris Pamela M.
Published: April 2012

The performance of many micro- and nanoscale devices depends on the ability to control interfacial thermal transport, which is predominantly mediated by phonons in semiconductor systems. The phonon transmissivity at an interface is therefore a quantity of interest. In this work, an empirical model, termed the thermal mismatch model, is developed to predict transmissivity at ideal interfaces between semiconductor materials, producing an excellent agreement with molecular dynamics simulations of wave packets. To investigate propagation through multilayered structures, this thermal mismatch model is then incorporated into a simulation scheme that represents wave packets as particles, showing a good agreement with a similar scheme that used molecular dynamics simulations as input [P. K. Schelling and S. R. Phillpot, J. Appl. Phys. 93, 5377 (2003)]. With these techniques validated for both single interfaces and superlattices, they are further used to identify ways to tune the transmissivity of multilayered structures. It is shown that by introducing intermediate layers of certain atomic masses, the total transmissivity can either be systematically enhanced or reduced compared to that of a single interface. Thus, this model can serve as a computationally inexpensive means of developing strategies to control phonon transmissivity in applications that may benefit from either enhancement (e.g., microelectronics) or reduction (e.g., thermoelectrics) in thermal transport.
MHC class I antigen processing distinguishes endogenous antigens based on their translation from cellular vs. viral mRNA
Authors: Dolan Brian P. , Sharma Aditi A. , Gibbs James S. , Cunningham Tshaka J. , Bennink Jack R. , Yewdell Jonathan W.
Published: April 2012

To better understand the generation of MHC class I-associated peptides, we used a model antigenic protein whose proteasome-mediated degradation is rapidly and reversibly controlled by Shield-1, a cell-permeant drug. When expressed from a stably transfected gene, the efficiency of antigen presentation is ∼2%, that is, one cell-surface MHC class I–peptide complex is generated for every 50 folded source proteins degraded upon Shield-1 withdrawal. By contrast, when the same protein is expressed by vaccinia virus, its antigen presentation efficiency is reduced ∼10-fold to values similar to those reported for other vaccinia virus-encoded model antigens. Virus infection per se does not modify the efficiency of antigen processing. Rather, the efficiency difference between cellular and virus-encoded antigens is based on whether the antigen is synthesized from transgene- vs. virus-encoded mRNA. Thus, class I antigen-processing machinery can distinguish folded proteins based on the precise details of their synthesis to modulate antigen presentation efficiency.
Superessential reactions in metabolic networks
Authors: Barve Aditya , Rodrigues João Frederico Matias , Wagner Andreas
Published: April 2012

The metabolic genotype of an organism can change through loss and acquisition of enzyme-coding genes, while preserving its ability to survive and synthesize biomass in specific environments. This evolutionary plasticity allows pathogens to evolve resistance to antimetabolic drugs by acquiring new metabolic pathways that bypass an enzyme blocked by a drug. We here study quantitatively the extent to which individual metabolic reactions and enzymes can be bypassed. To this end, we use a recently developed computational approach to create large metabolic network ensembles that can synthesize all biomass components in a given environment but contain an otherwise random set of known biochemical reactions. Using this approach, we identify a small connected core of 124 reactions that are absolutely superessential (that is, required in all metabolic networks). Many of these reactions have been experimentally confirmed as essential in different organisms. We also report a superessentiality index for thousands of reactions. This index indicates how easily a reaction can be bypassed. We find that it correlates with the number of sequenced genomes that encode an enzyme for the reaction. Superessentiality can help choose an enzyme as a potential drug target, especially because the index is not highly sensitive to the chemical environment that a pathogen requires. Our work also shows how analyses of large network ensembles can help understand the evolution of complex and robust metabolic networks.
Intramembrane proteolysis ofToxoplasmaapical membrane antigen 1 facilitates host-cell invasion but is dispensable for replication
Authors: Parussini Fabiola , Tang Qing , Moin Syed M. , Mital Jeffrey , Urban Sinisa , Ward Gary E.
Published: April 2012

Apical membrane antigen 1 (AMA1) is a conserved transmembrane adhesin of apicomplexan parasites that plays an important role in host-cell invasion.Toxoplasma gondiiAMA1 (TgAMA1) is secreted onto the parasite surface and subsequently released by proteolytic cleavage within its transmembrane domain. To elucidate the function of TgAMA1 intramembrane proteolysis, we used a heterologous cleavage assay to characterize the determinants within the TgAMA1 transmembrane domain (ALIAGLAVGGVLLLALLGGGCYFA) that govern its processing. Quantitative analysis revealed that the TgAMA1L/Gmutation enhanced cleavage by 13-fold compared with wild type. In contrast, the TgAMA1AG/FFmutation reduced cleavage by 30-fold, whereas the TgAMA1GG/FFmutation had a minor effect on proteolysis; mutating both motifs in a quadruple mutant blocked cleavage completely. We then complemented a TgAMA1 conditional knockout parasite line with plasmids expressing these TgAMA1 variants. Contrary to expectation, variants that increased or decreased TgAMA1 processing by >10-fold had no phenotypic consequences, revealing that the levels of rhomboid proteolysis in parasites are not delicately balanced. Only parasites transgenically expressing or carrying a true knock-in allele of the uncleavable TgAMA1AG/FF+GG/FFmutant showed a growth defect, which resulted from inhibiting invasion without perturbing intracellular replication. These data demonstrate that TgAMA1 cleavage plays a role in invasion, but refute a recently proposed model in which parasite replication within the host cell is regulated by intramembrane proteolysis of TgAMA1.
Evidence of a large-scale mechanosensing mechanism for cellular adaptation to substrate stiffness
Authors: Trichet Léa , Le Digabel Jimmy , Hawkins Rhoda J. , Vedula Sri Ram Krishna , Gupta Mukund , Ribrault Claire , Hersen Pascal , Voituriez Raphaël , Ladoux Benoît
Published: April 2012

Cell migration plays a major role in many fundamental biological processes, such as morphogenesis, tumor metastasis, and wound healing. As they anchor and pull on their surroundings, adhering cells actively probe the stiffness of their environment. Current understanding is that traction forces exerted by cells arise mainly at mechanotransduction sites, called focal adhesions, whose size seems to be correlated to the force exerted by cells on their underlying substrate, at least during their initial stages. In fact, our data show by direct measurements that the buildup of traction forces is faster for larger substrate stiffness, and that the stress measured at adhesion sites depends on substrate rigidity. Our results, backed by a phenomenological model based on active gel theory, suggest that rigidity-sensing is mediated by a large-scale mechanism originating in the cytoskeleton instead of a local one. We show that large-scale mechanosensing leads to an adaptative response of cell migration to stiffness gradients. In response to a step boundary in rigidity, we observe not only that cells migrate preferentially toward stiffer substrates, but also that this response is optimal in a narrow range of rigidities. Taken together, these findings lead to unique insights into the regulation of cell response to external mechanical cues and provide evidence for a cytoskeleton-based rigidity-sensing mechanism.
Lysocardiolipin acyltransferase 1 (ALCAT1) controls mitochondrial DNA fidelity and biogenesis through modulation of MFN2 expression
Authors: Li Jia , Liu Xiaolei , Wang Huayan , Zhang Weiping , Chan David C. , Shi Yuguang
Published: April 2012

Oxidative stress causes mitochondrial fragmentation and dysfunction in age-related diseases through unknown mechanisms. Cardiolipin (CL) is a phospholipid required for mitochondrial oxidative phosphorylation. The function of CL is determined by its acyl composition, which is significantly altered by the onset of age-related diseases. Here, we examine a role of acyl-CoA:lysocardiolipin acyltransferase lysocardiolipin acyltransferase 1 (ALCAT1), a lysocardiolipin acyltransferase that catalyzes pathological CL remodeling, in mitochondrial biogenesis. We show that overexpression of ALCAT1 causes mitochondrial fragmentation through oxidative stress and depletion of mitofusin mitofusin 2 (MFN2) expression. Strikingly, ALCAT1 overexpression also leads to mtDNA instability and depletion that are reminiscent of MFN2 deficiency. Accordingly, expression of MFN2 completely rescues mitochondrial fusion defect and respiratory dysfunction. Furthermore, ablation of ALCAT1 prevents mitochondrial fragmentation from oxidative stress by up-regulating MFN2 expression, mtDNA copy number, and mtDNA fidelity. Together, these findings reveal an unexpected role of CL remodeling in mitochondrial biogenesis, linking oxidative stress by ALCAT1 to mitochondrial fusion defect.
Robustness and accuracy of cell division in
Escherichia coli
in diverse cell shapes
Authors: Männik Jaan , Wu Fabai , Hol Felix J. H. , Bisicchia Paola , Sherratt David J. , Keymer Juan E. , Dekker Cees
Published: April 2012

Cell division in typical rod-shaped bacteria such as
Escherichia coli
shows a remarkable plasticity in being able to adapt to a variety of irregular cell shapes. Here, we investigate the roles of the Min system and the nucleoid-occlusion factor SlmA in supporting this adaptation. We study “squeezed”
E. coli
in narrow nanofabricated channels where these bacteria exhibit highly irregular shapes and large volumes. Despite the severely anomalous morphologies we find that most of these bacteria maintain their ability to divide into two equally sized daughters with an accuracy comparable to that of normal rod-shaped cells (about 4%). Deletion of either
slmA
or
minC
shows that the molecular systems associated with these genes are largely dispensable for accurate cell division in these irregular cell shapes. Using fluorescence time-lapse microscopy, we determine that the functionality of the Min system is affected by the cell shape, whereas the localization of a nucleoid relative to the cell division proteins (the divisome) remains unperturbed in a broad spectrum of morphologies, consistent with nucleoid occlusion. The observed positioning of the nucleoid relative to the divisome appears not to be affected by the nucleoid-occlusion factor SlmA. The current study underscores the importance of nucleoid occlusion in positioning the divisome and shows that it is robust against shape irregularities.
Uniform hexagonal graphene flakes and films grown on liquid copper surface
Authors: Geng Dechao , Wu Bin , Guo Yunlong , Huang Liping , Xue Yunzhou , Chen Jianyi , Yu Gui , Jiang Lang , Hu Wenping , Liu Yunqi
Published: April 2012

Unresolved problems associated with the production of graphene materials include the need for greater control over layer number, crystallinity, size, edge structure and spatial orientation, and a better understanding of the underlying mechanisms. Here we report a chemical vapor deposition approach that allows the direct synthesis of uniform single-layered, large-size (up to 10,000 μm
2
), spatially self-aligned, and single-crystalline hexagonal graphene flakes (HGFs) and their continuous films on liquid Cu surfaces. Employing a liquid Cu surface completely eliminates the grain boundaries in solid polycrystalline Cu, resulting in a uniform nucleation distribution and low graphene nucleation density, but also enables self-assembly of HGFs into compact and ordered structures. These HGFs show an average two-dimensional resistivity of 609 ± 200 Ω and saturation current density of 0.96 ± 0.15 mA/μm, demonstrating their good conductivity and capability for carrying high current density.
Pyruvate kinase M2 promotes de novo serine synthesis to sustain mTORC1 activity and cell proliferation
Authors: Ye Jiangbin , Mancuso Anthony , Tong Xuemei , Ward Patrick S. , Fan Jing , Rabinowitz Joshua D. , Thompson Craig B.
Published: April 2012

Despite the fact that most cancer cells display high glycolytic activity, cancer cells selectively express the less active M2 isoform of pyruvate kinase (PKM2). Here we demonstrate that PKM2 expression makes a critical regulatory contribution to the serine synthetic pathway. In the absence of serine, an allosteric activator of PKM2, glycolytic efflux to lactate is significantly reduced in PKM2-expressing cells. This inhibition of PKM2 results in the accumulation of glycolytic intermediates that feed into serine synthesis. As a consequence, PKM2-expressing cells can maintain mammalian target of rapamycin complex 1 activity and proliferate in serine-depleted medium, but PKM1-expressing cells cannot. Cellular detection of serine depletion depends on general control nonderepressible 2 kinase-activating transcription factor 4 (GCN2-ATF4) pathway activation and results in increased expression of enzymes required for serine synthesis from the accumulating glycolytic precursors. These findings suggest that tumor cells use serine-dependent regulation of PKM2 and GCN2 to modulate the flux of glycolytic intermediates in support of cell proliferation.
Intracerebral inoculation of pathological α-synuclein initiates a rapidly progressive neurodegenerative α-synucleinopathy in mice
Authors: Luk Kelvin C. , Kehm Victoria M. , Zhang Bin , O’Brien Patrick , Trojanowski John Q. , Lee Virginia M.Y.
Published: April 2012

The accumulation of misfolded proteins is a fundamental pathogenic process in neurodegenerative diseases. However, the factors that trigger aggregation of α-Synuclein (α-Syn), the principal component of the intraneuronal inclusions known as Lewy bodies (LBs), and Lewy neurites (LNs), which characterize Parkinson’s disease (PD) and dementia with LBs (DLB), are poorly understood. We show here that in young asymptomatic α-Syn transgenic (Tg) mice, intracerebral injections of brain homogenates derived from older Tg mice exhibiting α-Syn pathology accelerate both the formation of intracellular LB/LN-like inclusions and the onset of neurological symptoms in recipient animals. Pathological α-Syn propagated along major central nervous system (CNS) pathways to regions far beyond injection sites and reduced survival with a highly reproducible interval from injection to death in inoculated animals. Importantly, inoculation with α-Syn amyloid fibrils assembled from recombinant human α-Syn induced identical consequences. Furthermore, we show for the first time that synthetic α-Syn fibrils are wholly sufficient to initiate PD-like LBs/LNs and to transmit disease in vivo. Thus, our data point to a prion-like cascade in synucleinopathies whereby cell–cell transmission and propagation of misfolded α-Syn underlie the CNS spread of LBs/LNs. These findings open up new avenues for understanding the progression of PD and for developing novel therapeutics.
pIRS: Profile-based Illumina pair-end reads simulator
Authors: Hu Xuesong , Yuan Jianying , Shi Yujian , Lu Jianliang , Liu Binghang , Li Zhenyu , Chen Yanxiang , Mu Desheng , Zhang Hao , Li Nan , Yue Zhen , Bai Fan , Li Heng , Fan Wei
Published: April 2012

Motivation: The next-generation high-throughput sequencing technologies, especially from Illumina, have been widely used in re-sequencing and de novo assembly studies. However, there is no existing software that can simulate Illumina reads with real error and quality distributions and coverage bias yet, which is very useful in relevant software development and study designing of sequencing projects.

Results: We provide a software package, pIRS (profile-based Illumina pair-end reads simulator), which simulates Illumina reads with empirical Base-Calling and GC%-depth profiles trained from real re-sequencing data. The error and quality distributions as well as coverage bias patterns of simulated reads using pIRS fit the properties of real sequencing data better than existing simulators. In addition, pIRS also comes with a tool to simulate the heterozygous diploid genomes.

Availability: pIRS is written in C++ and Perl, and is freely available at ftp://ftp.genomics.org.cn/pub/pIRS/.

Contact:  fanweisz09@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
Beyond the cardiorenal anaemia syndrome: recognizing the role of iron deficiency
Authors: Macdougall Iain C. , Canaud Bernard , de Francisco Angel L.M. , Filippatos Gerasimos , Ponikowski Piotr , Silverberg Donald , van Veldhuisen Dirk J. , Anker Stefan D.
Published: April 2012

Growing awareness that heart failure, renal impairment, and anaemia are frequent co‐morbidities which can exacerbate one another in a vicious circle of clinical deterioration has led to the concept of the cardiorenal anaemia syndrome (CRAS). The role of iron deficiency within this complex interplay has been less well examined. Scrutiny of data from the recent FAIR‐HF trial raises a new hypothesis: is it time for ‘CRAS’ to be supplemented with new acronyms such as CRIDS (cardiorenal–iron deficiency syndrome) or even CRAIDS (cardiorenal–anaemia–iron deficiency syndrome)? Iron deficiency occurs frequently in heart failure patients with or without anaemia. It not only impairs oxygen transport through reduced erythropoiesis, but adversely affects oxidative metabolism, cellular energetics, and immune mechanisms, and the synthesis and degradation of complex molecules such as DNA. One large observational study in patients with heart failure found iron deficiency to be an independent predictor of death or urgent heart transplantation (hazard ratio 1.58, 95% confidence interval 1.14–2.17, P = 0.005). In the FAIR‐HF trial, i.v. iron therapy was associated with significant improvements in physical functioning in iron‐deficient patients with heart failure, even in non‐anaemic patients in whom haemoglobin levels did not change following i.v. iron administration. Key questions regarding the use of i.v. iron supplementation in the setting of heart failure merit exploration and could readily be answered by appropriately designed clinical trials. It is to be hoped that these important clinical trials are conducted, to permit a more subtle characterization of the patient's pathological condition and interventional requirements.
Steady-state Mantle–Melt Interactions in One Dimension: I. Equilibrium Transport and Melt Focusing
Authors: Asimow P. D. , Stolper E. M.
Published: April 2012

Mantle–melt interaction during melt transport is explored in one dimension and steady state. We reconsider the equivalence between one-dimensional steady equilibrium transport and batch melting. In the absence of diffusion and radioactivity, conservation of mass flux requires that the major and trace element compositions of melt and solid at each point are the same as is generated by batch melting the source composition at the same pressure and temperature. Energy conservation requires that temperature and extent of melting are independent of melt migration except for irreversible source terms related to viscous compaction and gravitational energy release. The equivalence of phase compositions at each pressure between steady-state equilibrium transport and batch melting simplifies melt transport calculations. We examine the effects of increasing the melt flux to simulate melt focusing by channeling or by two-dimensional flow with converging melt streamlines. Melt focusing modifies the mineralogy of both residual matrix and erupted melt. We use MELTS calculations to model the formation of dunite by this mechanism and quantify the melt flux required to exhaust orthopyroxene from the residue as a function of pressure. The model dunites are found to be similar to natural dunites observed in the mantle section of ophiolite sequences.
Multidimensional regulation of gene expression in the C. elegans embryo
Authors: Murray John Isaac , Boyle Thomas J. , Preston Elicia , Vafeados Dionne , Mericle Barbara , Weisdepp Peter , Zhao Zhongying , Bao Zhirong , Boeck Max , Waterston Robert H.
Published: April 2012

How cells adopt different expression patterns is a fundamental question of developmental biology. We quantitatively measured reporter expression of 127 genes, primarily transcription factors, in every cell and with high temporal resolution in C. elegans embryos. Embryonic cells are highly distinct in their gene expression; expression of the 127 genes studied here can distinguish nearly all pairs of cells, even between cells of the same tissue type. We observed recurrent lineage-regulated expression patterns for many genes in diverse contexts. These patterns are regulated in part by the TCF-LEF transcription factor POP-1. Other genes' reporters exhibited patterns correlated with tissue, position, and left–right asymmetry. Sequential patterns both within tissues and series of sublineages suggest regulatory pathways. Expression patterns often differ between embryonic and larval stages for the same genes, emphasizing the importance of profiling expression in different stages. This work greatly expands the number of genes in each of these categories and provides the first large-scale, digitally based, cellular resolution compendium of gene expression dynamics in live animals. The resulting data sets will be a useful resource for future research.
Information sources at play
Authors: Rivano Eckerdal Johanna
Published: April 2012

Purpose

The aim of this article is to suggest that the information interaction between midwives and young women during counselling meetings about contraceptives can be approached as loci of knowledge production and discuss the consequences this has for the understanding of information practices. The overarching question is: how is knowledge produced during the interaction between the midwives and the young women and what roles do their bodies play in this interaction?

Design/methodology/approach

Qualitative methods inspired by ethnography were used, including conversation transcripts of ten counselling meetings, 19 interviews and participatory observations at five youth centres in the South of Sweden. The study took place over a period of nine months. The feministic conceptual framework presented by Donna Haraway concerning knowledge production was used to analyse the material.

Findings

As they meet, both midwives and young women are information sources to each other, and the information conveyed is negotiated in both words and actions. Both parties are involved in a careful negotiation to establish what information is needed and appropriate for the situation at hand, but the midwives have the final say. However, the midwives balance between exerting a generalised expertise and entering in a situated dialogue with the young women.

Practical implications

This study may contribute to awareness among information professionals of counselling meetings as information interactions where both words and actions are important as well as the inequality of power in that interaction.

Originality/value

This study contributes to library and information studies by broadening the understanding of what an information source may be and by exploring the usefulness of feminist researcher Donna Haraway's analytical tools for understanding information interactions as knowledge producing negotiations.
The role of social cognition in downsizing decisions
Authors: Dwyer Dale J. , Arbelo Morgan
Published: April 2012

Purpose

The purpose of this paper is to learn how managers make downsizing decisions.

Design/methodology/approach

Participants read a created organizational scenario and 25 hypothetical employee profiles and then chose five employees to lay off.

Findings

Older and minority applicants were chosen most often. No significance was found for performance. Rater group membership in race, gender, and age were significant predictors of layoff decisions.

Research limitations/implications

Because the participants were in a controlled environment they may have disregarded other information often available to decision makers. The majority of the sample was students who may be unrepresentative of managers who make layoff decisions. The inclusion of managers who have made downsizing decisions was designed to help address this limitation.

Practical implications

An employer's use of personal characteristics in making downsizing decisions may ultimately affect the aftermath of downsizing.

Originality/value

This is one of the first studies to study the decision‐making process of layoffs.
Perceptions of international students on service quality delivery in a Malaysian public university
Authors: Njie Baboucarr , Asimiran Soaib , Baki Roselan
Published: April 2012

Purpose

The purpose of this study is to explore the perceptions of international students of service quality delivery (SQD) in a Malaysian public university.

Design/methodology/approach

The study was limited to the University's immediate physical environment and its associated human and systems‐based services. The physical environment in this study focused on the University buildings and all their contents, for example, the physical structures and infrastructure and related services. Qualitative methods were used and purposeful sampling was employed to select six international students from three different regions who were attending graduate level programs in a Malaysian public university to give their views on the quality of service delivery directly linked to the physical environment of the university. An understanding of students' thoughts and expectations of the quality of services offered, especially given that they were from varied social and cultural settings, is crucial to the adoption of measures for continuous improvement in today's customer driven higher educational market.

Findings

The results show that the university is appreciated for its environmental friendly vegetation, numerous facilities and several policies and regulations allied to its environment but they also show gaps between the well developed policies and their corresponding implementation; the results also evoke the differences in understanding and implementation of services, requiring empathy in today's education world, between senior staff and their junior counterparts as well as interpretation of experiences of services encountered by international students.

Originality/value

The findings and discussion, especially with regard to the systems and human related service responses, could serve as a base for understanding some of the thoughts of international students and could be replicated on other campuses with a view to understanding how other students feel about their physical environments and the related services as well.