bluuebunny/crossref_metadata_2025 huggingface dataset:
Repeated‐sprint performance and vastus lateralis oxygenation: Effect of limited O2 availability
Authors: Billaut F. , Buchheit M.
Published: January 2013

This study examined the influence of muscle deoxygenation and reoxygenation on repeated‐sprint performance via manipulation of O2 delivery. Fourteen team‐sport players performed 10 10‐s sprints (30‐s recovery) under normoxic (NM: FIO2 0.21) and acute hypoxic (HY: FIO2 0.13) conditions in a randomized, single‐blind fashion and crossover design. Mechanical work was calculated and arterial O2 saturation (SpO2) was estimated via pulse oximetry for every sprint. Muscle deoxyhemoglobin concentration ([HHb]) was monitored continuously by near‐infrared spectroscopy. Differences between NM and HY data were analyzed for practical significance using magnitude‐based inferences. HY reduced SpO2 (–10.7 ± 1.9%, with chances to observe a higher/similar/lower value in HY of 0/0/100%) and mechanical work (–8.2 ± 2.1%; 0/0/100%). Muscle deoxygenation increased during sprints in both environments, but was almost certainly higher in HY (12.5 ± 3.1%, 100/0/0%). Between‐sprint muscle reoxygenation was likely more attenuated in HY (–11.1 ± 11.9%; 2/7/91%). The impairment in mechanical work in HY was very largely correlated with HY‐induced attenuation in muscle reoxygenation (r = 0.78, 90% confidence limits: 0.49; 0.91). Repeated‐sprint performance is related, in part, to muscle reoxygenation capacity during recovery periods. These results extend previous findings that muscle O2 availability is important for prolonged repeated‐sprint performance, in particular when the exercise is taken in hypoxia.
Generation of an artificial ring chromosome in Arabidopsis by Cre/LoxP‐mediated recombination
Authors: Murata Minoru , Shibata Fukashi , Hironaka Akiko , Kashihara Kazunari , Fujimoto Satoru , Yokota Etsuko , Nagaki Kiyotaka
Published: January 2013

A eukaryotic chromosome consists of a centromere, two telomeres and a number of replication origins, and ‘artificial chromosomes’ may be created in yeast and mammals when these three elements are artificially joined and introduced into cells. Plant artificial chromosomes (PACs) have been suggested as new vectors for the development of new crops and as tools for basic research on chromosomes. However, indisputable PAC formation has not yet been confirmed. Here, we present a method for generating PACs in the model plant Arabidopsis thaliana using the Cre/LoxP and Activator/Dissociation element systems. The successfully generated PAC, designated AtARC1 (A. thaliana artificial ring chromosome 1), originated from a centromeric edge of the long arm of chromosome 2, but its size (2.85 Mb) is much smaller than that of the original chromosome (26.3 Mb). Although AtARC1 contains only a short centromere domain consisting of 180 bp repeats approximately 250 kb in length, compared with the 3 Mb domain on the original chromosome 2, centromere‐specific histone H3 (HTR12) was detected on the centromeric region. This result supported the observed stability of the PAC during mitosis in the absence of selection, and transmission of the PAC to the next generation through meiosis. Because AtARC1 contains a unique LoxP site driven by the CaMV 35S promoter, it is possible to introduce a selectable marker and desired transgenes into AtARC1 at the LoxP site using Cre recombinase. Therefore, AtARC1 meets the criteria for a PAC and is a promising vector.
The cost‐effectiveness of platelet additive solution to prevent allergic transfusion reactions
Authors: Kacker Seema , Ness Paul M. , Savage William J. , Frick Kevin D. , McCullough Jeffrey , King Karen E. , Tobian Aaron A.R.
Published: January 2013

Background

Allergic transfusion reactions (ATRs) are among the most common complications of transfusion. Storage in platelet additive solution (PAS) has been shown to reduce ATRs from apheresis platelets (APs). This study evaluated the cost‐effectiveness of using PAS storage as an alternative method to reduce ATRs.

Study Design and Methods

A Markov‐based decision tree was constructed to compare ATR rates and associated costs expected from current practice and from alternative strategies of using APs stored in PAS. The potential use of pretransfusion medication was also incorporated. Using a hospital perspective and including direct medical expenses only (US$2012), Monte Carlo microsimulations were run to evaluate outcomes under a base‐case analysis. One‐way and probabilistic sensitivity analyses were used to assess outcome uncertainty.

Results

Under base‐case variables, using APs stored in PAS for all patients as an initial transfusion protocol is expected to avert ATRs and associated costs, compared to current practice. Using PAS for all patients along with pretransfusion medication would be cost‐saving only when the additional cost of PAS is below $9.14. If PAS storage could eliminate pretransfusion medication use, it is expected to result in cost savings when the additional unit cost of PAS is under $11.90. At a PAS cost of $15, averting one ATR would cost $701.95. Using PAS storage only in response to recurring mild ATRs is associated with cost savings under all costs of PAS evaluated.

Conclusions

Using PAS storage for all AP transfusions to prevent ATRs may be financially and clinically beneficial, compared to current practice.
Discrimination of phase altered targets by an echolocating Atlantic bottlenose dolphin
Authors: Ibsen Stuart D. , Muller Mark W. , Au Whitlow W. L. , Nachtigall Paul E. , Breese Marlee
Published: January 2013

Sensitivity of echolocating dolphins to phase changes within echoes may be a vital piece of information when constructing echolocation models. Previous experiments have yielded ambiguous results leaving it unclear what cues might have been used by passively listening dolphins to discriminate between different phase altered signals. This study used a phantom echo generator to produce computer controlled echoes. The dolphin interacted with the system in a real echolocation task to discriminate between simulated targets that were unaltered and those that had a 180° phase shift. The frequency amplitude spectral content between the two targets was the same. There were no temporal differences between the two targets. The only cue that the dolphin could use to discriminate between them was the 180° phase shift. The dolphin preformed at a success level of 40% in discriminating the two echoes. This indicates that the 180° phase shift was not perceived.
Analysis of concert hall acoustics via visualizations of time-frequency and spatiotemporal responses
Authors: Pätynen Jukka , Tervo Sakari , Lokki Tapio
Published: January 2013

Acousticians and other practitioners alike often describe acoustic conditions in performance spaces with standard objective parameters. Apart from a few exceptions, the parameters are calculated by integrating the sound energy of the impulse responses over time; this makes them inadequate for researching the acoustics in detail, especially in the early part of the room impulse response. This paper proposes a method based on time-frequency and spatiotemporal presentations to overcome the lack of detail in the standard analysis. In brief, the proposed methods visualize the cumulative development of the sound field as a function of frequency or direction by forward-integrating the energy in the impulse response in short time frames. Analysis on the measurements from six concert halls concentrates particularly on interpreting the results in light of the seat dip effect. Earlier research has concluded that the seat dip effect is reduced by reflection from low overhead surfaces. In contrast, the current results indicate that the seat dip attenuation in the frequency response is corrected the best when the hall provides most lateral reflections. These findings suggest that the proposed analysis is suitable for explaining concert hall acoustics in detail.
Localization and tracking of moving objects in two-dimensional space by echolocation
Authors: Matsuo Ikuo
Published: January 2013

Bats use frequency-modulated echolocation to identify and capture moving objects in real three-dimensional space. Experimental evidence indicates that bats are capable of locating static objects with a range accuracy of less than 1 μs. A previously introduced model estimates ranges of multiple, static objects using linear frequency modulation (LFM) sound and Gaussian chirplets with a carrier frequency compatible with bat emission sweep rates. The delay time for a single object was estimated with an accuracy of about 1.3 μs by measuring the echo at a low signal-to-noise ratio (SNR). The range accuracy was dependent not only on the SNR but also the Doppler shift, which was dependent on the movements. However, it was unclear whether this model could estimate the moving object range at each timepoint. In this study, echoes were measured from the rotating pole at two receiving points by intermittently emitting LFM sounds. The model was shown to localize moving objects in two-dimensional space by accurately estimating the object's range at each timepoint.
Analytical approximations for low frequency band gaps in periodic arrays of elastic shells
Authors: Krynkin Anton , Umnova Olga , Taherzadeh Shahram , Attenborough Keith
Published: January 2013

This paper presents and compares three analytical methods for calculating low frequency band gap boundaries in doubly periodic arrays of resonating thin elastic shells. It is shown that both Foldy-type equations (derived with lattice sum expansions in the vicinity of its poles) and a self-consistent scheme could be used to predict boundaries of low-frequency (below the first Bragg band gap) band gaps due to axisymmetric (n=0) and dipolar (n=1) shell resonances. The accuracy of the former method is limited to low filling fraction arrays, however, as the filling fraction increases the application of the matched asymptotic expansions could significantly improve approximations of the upper boundary of band gap related to axisymmetric resonance. The self-consistent scheme is shown to be very robust and gives reliable results even for dense arrays with filling fractions around 70%. The estimates of band gap boundaries can be used in analyzing the performance of periodic arrays (in terms of the band gap width) without using full semi-analytical and numerical models. The results are used to predict the dependence of the position and width of the low frequency band gap on the properties of shells and their periodic arrays.
Voice quality and tone identification in White Hmong
Authors: Garellek Marc , Keating Patricia , Esposito Christina M. , Kreiman Jody
Published: January 2013

This study investigates the importance of source spectrum slopes in the perception of phonation by White Hmong listeners. In White Hmong, nonmodal phonation (breathy or creaky voice) accompanies certain lexical tones, but its importance in tonal contrasts is unclear. In this study, native listeners participated in two perceptual tasks, in which they were asked to identify the word they heard. In the first task, participants heard natural stimuli with manipulated F0 and duration (phonation unchanged). Results indicate that phonation is important in identifying the breathy tone, but not the creaky tone. Thus, breathiness can be viewed as contrastive in White Hmong. Next, to understand which parts of the source spectrum listeners use to perceive contrastive breathy phonation, source spectrum slopes were manipulated in the second task to create stimuli ranging from modal to breathy sounding, with F0 held constant. Results indicate that changes in H1-H2 (difference in amplitude between the first and second harmonics) and H2-H4 (difference in amplitude between the second and fourth harmonics) are independently important for distinguishing breathy from modal phonation, consistent with the view that the percept of breathiness is influenced by a steep drop in harmonic energy in the lower frequencies.
Doppler-based motion compensation algorithm for focusing the signature of a rotorcraft
Authors: Goldman Geoffrey H.
Published: January 2013

A computationally efficient algorithm was developed and tested to compensate for the effects of motion on the acoustic signature of a rotorcraft. For target signatures with large spectral peaks that vary slowly in amplitude and have near constant frequency, the time-varying Doppler shift can be tracked and then removed from the data. The algorithm can be used to preprocess data for classification, tracking, and nulling algorithms. The algorithm was tested on rotorcraft data. The average instantaneous frequency of the first harmonic of a rotorcraft was tracked with a fixed-lag smoother. Then, state space estimates of the frequency were used to calculate a time warping that removed the effect of a time-varying Doppler shift from the data. The algorithm was evaluated by analyzing the increase in the amplitude of the harmonics in the spectrum of a rotorcraft. The results depended upon the frequency of the harmonics and the processing interval duration. Under good conditions, the results for the fundamental frequency of the target (∼11 Hz) almost achieved an estimated upper bound. The results for higher frequency harmonics had larger increases in the amplitude of the peaks, but significantly lower than the estimated upper bounds.
The effects of unmodulated carrier fringes on the detection of frequency modulation
Authors: Byrne Andrew J. , Viemeister Neal F. , Stellmack Mark A.
Published: January 2013

Detection thresholds for 100 ms of either 5- or 20-Hz frequency modulation (FM) were measured at various temporal positions within a 600-ms, 4-kHz pure-tone carrier. The results indicated that the temporal position of the signal relative to the fringe influences detection thresholds, including an effect that is reminiscent of auditory backward recognition masking. A task involving frequency increments, rather than sinusoidal FM, yielded similar results. Additional manipulation of total carrier duration indicated that FM detection thresholds improve as the duration of the forward fringe increases, while a backward fringe only degrades performance in the absence of any forward fringe. The results suggest that listeners are insensitive to subtle frequency changes that occur at the onset of a longer stimulus and that the interaction between the opposing effects of the forward and backward fringes is not additive.
Near-field to far-field projection algorithm for free-field or buried scatterer
Authors: Sarkissian Angie , Houston Brian , Bucaro Joseph , Kraus Larry
Published: January 2013

A near-field to far-field projection algorithm is applied to a structure in the free-field case and generalized to a buried scatterer. The method of superposition is applied where the scattered field produced by the target may be approximated by the field produced by a number of point sources placed near the target. The source strengths are determined by requiring the field they produce to satisfy boundary conditions on the measurement surface. In the free-field case, the expression of the Green's function is simple. In the buried case, the two-domain Green's function may be expressed as an integral over special functions. Once the source strengths are determined, the far-field is computed as a superposition of the fields produced by the individual sources. The algorithm is tested on numerically generated data.
Paralinguistic mechanisms of production in human “beatboxing”: A real-time magnetic resonance imaging study
Authors: Proctor Michael , Bresch Erik , Byrd Dani , Nayak Krishna , Narayanan Shrikanth
Published: January 2013

Real-time Magnetic Resonance Imaging (rtMRI) was used to examine mechanisms of sound production by an American male beatbox artist. rtMRI was found to be a useful modality with which to study this form of sound production, providing a global dynamic view of the midsagittal vocal tract at frame rates sufficient to observe the movement and coordination of critical articulators. The subject's repertoire included percussion elements generated using a wide range of articulatory and airstream mechanisms. Many of the same mechanisms observed in human speech production were exploited for musical effect, including patterns of articulation that do not occur in the phonologies of the artist's native languages: ejectives and clicks. The data offer insights into the paralinguistic use of phonetic primitives and the ways in which they are coordinated in this style of musical performance. A unified formalism for describing both musical and phonetic dimensions of human vocal percussion performance is proposed. Audio and video data illustrating production and orchestration of beatboxing sound effects are provided in a companion annotated corpus.
Determining probability distribution of coherent integration time near 133 Hz and 1346 km in the Pacific Ocean
Authors: Spiesberger John L.
Published: January 2013

The hypothesis tested is that internal gravity waves limit the coherent integration time of sound at 1346 km in the Pacific ocean at 133 Hz and a pulse resolution of 0.06 s. Six months of continuous transmissions at about 18 min intervals are examined. The source and receiver are mounted on the bottom of the ocean with timing governed by atomic clocks. Measured variability is only due to fluctuations in the ocean. A model for the propagation of sound through fluctuating internal waves is run without any tuning with data. Excellent resemblance is found between the model and data's probability distributions of integration time up to five hours.
Simulations of ultrasound propagation in random arrangements of elliptic scatterers: Occurrence of two longitudinal waves
Authors: Mézière Fabien , Muller Marie , Dobigny Blandine , Bossy Emmanuel , Derode Arnaud
Published: January 2013

Ultrasound propagation in clusters of elliptic (two-dimensional) or ellipsoidal (three-dimensional) scatterers randomly distributed in a fluid is investigated numerically. The essential motivation for the present work is to gain a better understanding of ultrasound propagation in trabecular bone. Bone microstructure exhibits structural anisotropy and multiple wave scattering. Some phenomena remain partially unexplained, such as the propagation of two longitudinal waves. The objective of this study was to shed more light on the occurrence of these two waves, using finite-difference simulations on a model medium simpler than bone. Slabs of anisotropic, scattering media were randomly generated. The coherent wave was obtained through spatial and ensemble-averaging of the transmitted wavefields. When varying relevant medium parameters, four of them appeared to play a significant role for the observation of two waves: (i) the solid fraction, (ii) the direction of propagation relatively to the scatterers orientation, (iii) the ability of scatterers to support shear waves, and (iv) a continuity of the solid matrix along the propagation. These observations are consistent with the hypothesis that fast waves are guided by the locally plate/bar-like solid matrix. If confirmed, this interpretation could significantly help developing approaches for a better understanding of trabecular bone micro-architecture using ultrasound.
Suppression tuning of distortion-product otoacoustic emissions: Results from cochlear mechanics simulation
Authors: Liu Yi-Wen , Neely Stephen T.
Published: January 2013

This paper presents the results of simulating the acoustic suppression of distortion-product otoacoustic emissions (DPOAEs) from a computer model of cochlear mechanics. A tone suppressor was introduced, causing the DPOAE level to decrease, and the decrement was plotted against an increasing suppressor level. Suppression threshold was estimated from the resulting suppression growth functions (SGFs), and suppression tuning curves (STCs) were obtained by plotting the suppression threshold as a function of suppressor frequency. Results show that the slope of SGFs is generally higher for low-frequency suppressors than high-frequency suppressors, resembling those obtained from normal hearing human ears. By comparing responses of normal (100%) vs reduced (50%) outer-hair-cell sensitivities, the model predicts that the tip-to-tail difference of the STCs correlates well with that of intra-cochlear iso-displacement tuning curves. The correlation is poorer, however, between the sharpness of the STCs and that of the intra-cochlear tuning curves. These results agree qualitatively with what was recently reported from normal-hearing and hearing-impaired human subjects, and examination of intra-cochlear model responses can provide the needed insight regarding the interpretation of DPOAE STCs obtained in individual ears.
An experimental evaluation of the impact of scattering on sound field diffusivity
Authors: Prodi Nicola , Visentin Chiara
Published: January 2013

This work provides a systematic experimental evaluation of the impact of scattering on sound field diffusivity in a proportionate medium-small sized room. A scale model is set up in many ways by increasing the amount of scattering, and detailing measurements of the reverberation time in each case. With the aid of statistical tools, the role of scattering in the process of achieving a diffuse sound field from initially non-diffuse conditions is outlined and a set of reference scattering threshold values is derived. It is found that the same values ensure the validity of the Sabine formula when corrections are adopted in its application. Reverberation time is also predicted in non-diffuse conditions by the Nilsson approach, and its performance is systematically compared with measurements. The Nilsson method was a better predictor of reverberation time under non-diffuse conditions than classical reverberation time formulas. However, for diffuse sound fields, the same method tended to diverge from measured values. An application using more realistic room conditions is developed together with computer simulations. The results outline that there is limited benefit to using computer-aided design models instead of simple formulas to predict reverberation time for non-diffuse sound fields in proportionate medium-small sized rooms.
Retrieval of Green's function in the radiative transfer regime
Authors: Weaver Richard L.
Published: January 2013

The field–field correlation function of an imperfectly diffuse acoustic field is shown to equal the (time derivative of) Green's function times the specific intensity of the noise at the position of the pseudo-source directed toward the pseudo-receiver. The identity is established in a high frequency limit in which stations are separated by distances large compared to a wavelength and in which equal-time correlations vary smoothly in space. The specific intensity is governed by a radiative transport equation. This observation permits interpretation of correlation amplitudes and promises to facilitate the retrieval of attenuation, site amplification factors, and scattering strengths from noise correlations.
Nonlinear resonance behavior and linear shell estimates for Definity™ and MicroMarker™ assessed with acoustic microbubble spectroscopy
Authors: Helfield Brandon L. , Goertz David E.
Published: January 2013

There is a growing interest in microbubble based ultrasound contrast imaging applications in the 5–15 MHz range. In this study, individual microbubbles were insonified at low pressures (≤ 25 kPa) using an “acoustic spectroscopy” approach which entailed transmitting a sequence of tone bursts with center frequencies ranging from 4 to 13.5 MHz. The fundamental (transmit) frequency radial excursion amplitude was calculated from the scattered signals to produce a resonance curve for each bubble. For diameters between 2.5 to 4 μm, 69% of Target-Ready MicroMarker™ (Bracco, Geneva; Visualsonics, Canada) exhibited asymmetric resonance, characterized by a skewing of the resonance curve and indicative of nonlinear behavior. For Definity™ (Lantheus Medical Imaging, N. Billerica, MA), these responses were observed for 8% of diameters between 1.7 to 3.1 μm. For the subset of bubbles exhibiting linear, symmetric resonance curves, resonant frequencies, shell elasticity, and viscosity values were estimated. Between 10 to 12 MHz, for example, Target-Ready MicroMarker between 2.7 to 3.3 μm in diameter was resonant, where Definity was resonant between 1.7 to 2.6 μm. From 4 to 13.5 MHz, Target-Ready MicroMarker is characterized by a stiffer shell (3 < χ0 < 5) N/m than Definity (0.5 < χ0 < 2.5) N/m, and distinct strain-softening and shear-thinning rheological behavior. For Definity, no clear strain or shear-rate dependence of the shell properties is evident.
Success May Require Being Direct
Authors: Oviedo-Orta Ernesto
Published: January 2013

Injection of tuberculosis vaccine directly into the lymph nodes is more effective than subcutaneous vaccination.
Cultivation of an Obligate Fe(II)-Oxidizing Lithoautotrophic Bacterium Using Electrodes
Authors: Summers Zarath M. , Gralnick Jeffrey A. , Bond Daniel R.
Published: January 2013

Fe(II)-oxidizing aerobic bacteria are poorly understood, due in part to the difficulties involved in laboratory cultivation. Specific challenges include (i) providing a steady supply of electrons as Fe(II) while (ii) managing rapid formation of insoluble Fe(III) oxide precipitates and (iii) maintaining oxygen concentrations in the micromolar range to minimize abiotic Fe(II) oxidation. Electrochemical approaches offer an opportunity to study bacteria that require problematic electron donors or acceptors in their respiration. In the case of Fe(II)-oxidizing bacteria, if the electron transport machinery is able to oxidize metals at the outer cell surface, electrodes poised at potentials near those of natural substrates could serve as electron donors, eliminating concentration issues, side reactions, and mineral end products associated with metal oxidation. To test this hypothesis, the marine isolate
Mariprofundus ferrooxydans
PV-1, a neutrophilic obligate Fe(II)-oxidizing autotroph, was cultured using a poised electrode as the sole energy source. When cells grown in Fe(II)-containing medium were transferred into a three-electrode electrochemical cell, a cathodic (negative) current representing electron uptake by bacteria was detected, and it increased over a period of weeks. Cultures scraped from a portion of the electrode and transferred into sterile reactors consumed electrons at a similar rate. After three transfers in the absence of Fe(II), electrode-grown biofilms were studied to determine the relationship between donor redox potential and respiration rate. Electron microscopy revealed that under these conditions,
M. ferrooxydans
PV-1 attaches to electrodes and does not produce characteristic iron oxide stalks but still appears to exhibit bifurcate cell division.

IMPORTANCE
Electrochemical cultivation, supporting growth of bacteria with a constant supply of electron donors or acceptors, is a promising tool for studying lithotrophic species in the laboratory. Major pitfalls present in standard cultivation methods used for metal-oxidizing microbes can be avoided by the use of an electrode as the sole electron donor. Electrochemical cultivation also offers a window into the poorly understood metabolism of microbes such as obligate Fe(II), Mn(II), or S
0
oxidizers by replacing the electron source with the controlled surface of an electrode. The elucidation of redox-dependent behavior of these microbes could enhance industrial applications tuned to oxidation of specific metals, provide insight into how bacteria evolved to compete with oxygen for reactive metal species, and model geochemical impacts of their metabolism in the environment.
Control of Candida albicans Metabolism and Biofilm Formation by Pseudomonas aeruginosa Phenazines
Authors: Morales Diana K. , Grahl Nora , Okegbe Chinweike , Dietrich Lars E. P. , Jacobs Nicholas J. , Hogan Deborah A.
Published: January 2013

Candida albicans
has developmental programs that govern transitions between yeast and filamentous morphologies and between unattached and biofilm lifestyles. Here, we report that filamentation, intercellular adherence, and biofilm development were inhibited during interactions between
Candida albicans
and
Pseudomonas aeruginosa
through the action of
P. aeruginosa
-produced phenazines. While phenazines are toxic to
C. albicans
at millimolar concentrations, we found that lower concentrations of any of three different phenazines (pyocyanin, phenazine methosulfate, and phenazine-
1
-carboxylate) allowed growth but affected the development of
C. albicans
wrinkled colony biofilms and inhibited the fungal yeast-to-filament transition. Phenazines impaired
C. albicans
growth on nonfermentable carbon sources and led to increased production of fermentation products (ethanol, glycerol, and acetate) in glucose-containing medium, leading us to propose that phenazines specifically inhibited respiration. Methylene blue, another inhibitor of respiration, also prevented the formation of structured colony biofilms. The inhibition of filamentation and colony wrinkling was not solely due to lowered extracellular pH induced by fermentation. Compared to smooth, unstructured colonies, wrinkled colony biofilms had higher oxygen concentrations within the colony, and wrinkled regions of these colonies had higher levels of respiration. Together, our data suggest that the structure of the fungal biofilm promotes access to oxygen and enhances respiratory metabolism and that the perturbation of respiration by bacterial molecules such as phenazines or compounds with similar activities disrupts these pathways. These findings may suggest new ways to limit fungal biofilms in the context of disease.

IMPORTANCE
Many of the infections caused by
Candida albicans
, a major human opportunistic fungal pathogen, involve both morphological transitions and the formation of surface-associated biofilms. Through the study of
C. albicans
interactions with the bacterium
Pseudomonas aeruginosa
, which often coinfects with
C. albicans
, we have found that
P. aeruginosa
-produced phenazines modulate
C. albicans
metabolism and, through these metabolic effects, impact cellular morphology, cell-cell interactions, and biofilm formation. We suggest that the structure of
C. albicans
biofilms promotes access to oxygen and enhances respiratory metabolism and that the perturbation of respiration by phenazines inhibits biofilm development. Our findings not only provide insight into interactions between these species but also provide valuable insights into novel pathways that could lead to the development of new therapies to treat
C. albicans
infections.
NEAT1 Long Noncoding RNA and Paraspeckle Bodies Modulate HIV-1 Posttranscriptional Expression
Authors: Zhang Quan , Chen Chia-Yen , Yedavalli Venkat S. R. K. , Jeang Kuan-Teh
Published: January 2013

Most of the human genome is transcribed into protein-noncoding RNAs (ncRNAs), including small ncRNAs and long ncRNAs (lncRNAs). Over the past decade, rapidly emerging evidence has increasingly supported the view that lncRNAs serve key regulatory and functional roles in mammal cells. HIV-1 replication relies on various cell functions. To date, while the involvement of host protein factors and microRNAs (miRNAs) in the HIV-1 life cycle has been extensively studied, the relationship between lncRNAs and HIV-1 remains uncharacterized. Here, we have profiled 83 disease-related lncRNAs in HIV-1-infected T cells. We found NEAT1 to be one of several lncRNAs whose expression is changed by HIV-1 infection, and we have characterized its role in HIV-1 replication. We report here that the knockdown of NEAT1 enhances virus production through increased nucleus-to-cytoplasm export of Rev-dependent instability element (INS)-containing HIV-1 mRNAs.

IMPORTANCE
Long protein-noncoding RNAs (lncRNAs) play roles in regulating gene expression and modulating protein activities. There is emerging evidence that lncRNAs are involved in the replication of viruses. To our knowledge, this report is the first to characterize a role contributed by an lncRNA, NEAT1, to HIV-1 replication. NEAT1 is essential for the integrity of the nuclear paraspeckle substructure. Based on our findings from NEAT1 knockdown, we have identified the nuclear paraspeckle body as another important subcellular organelle for HIV-1 replication.
Host Pathways Important for Coxiella burnetii Infection Revealed by Genome-Wide RNA Interference Screening
Authors: McDonough Justin A. , Newton Hayley J. , Klum Scott , Swiss Rachel , Agaisse Hervé , Roy Craig R.
Published: January 2013

Coxiella burnetii
is an intracellular pathogen that replicates within a lysosome-like vacuole. A Dot/Icm type IVB secretion system is used by
C. burnetii
to translocate effector proteins into the host cytosol that likely modulate host factor function. To identify host determinants required for
C. burnetii
intracellular growth, a genome-wide screen was performed using gene silencing by small interfering RNA (siRNA). Replication of
C. burnetii
was measured by immunofluorescence microscopy in siRNA-transfected HeLa cells. Newly identified host factors included components of the retromer complex, which mediates cargo cycling between the endocytic pathway and the Golgi apparatus. Reducing the levels of the retromer cargo-adapter VPS26-VPS29-VPS35 complex or retromer-associated sorting nexins abrogated
C. burnetii
replication. Several genes, when silenced, resulted in enlarged vacuoles or an increased number of vacuoles within
C. burnetii-
infected cells. Silencing of the
STX17
gene encoding syntaxin-17 resulted in a striking defect in homotypic fusion of vacuoles containing
C. burnetii
, suggesting a role for syntaxin-17 in regulating this process. Lastly, silencing host genes needed for
C. burnetii
replication correlated with defects in the translocation of Dot/Icm effectors, whereas, silencing of genes that affected vacuole morphology, but did not impact replication, did not affect Dot/Icm translocation. These data demonstrate that
C. burnetii
vacuole maturation is important for creating a niche that permits Dot/Icm function. Thus, genome-wide screening has revealed host determinants involved in sequential events that occur during
C. burnetii
infection as defined by bacterial uptake, vacuole transport and acidification, activation of the Dot/Icm system, homotypic fusion of vacuoles, and intracellular replication.

IMPORTANCE
Q fever in humans is caused by the bacterium
Coxiella burnetii
. Infection with
C. burnetii
is marked by its unique ability to replicate within a large vacuolar compartment inside cells that resembles the harsh, acidic environment of a lysosome. Central to its pathogenesis is the delivery of bacterial effector proteins into the host cell cytosol by a Dot/Icm type IVB secretion system. These proteins can interact with and manipulate host factors, thereby leading to creation and maintenance of the vacuole that the bacteria grow within. Using high-throughput genome-wide screening in human cells, we identified host factors important for several facets of
C. burnetii
infection, including vacuole transport and membrane fusion events that promote vacuole expansion. In addition, we show that maturation of the
C. burnetii
vacuole is necessary for creating an environment permissive for the Dot/Icm delivery of bacterial effector proteins into the host cytosol.
Malaria and the conducting system of the heart
Authors: Bhat Smitha , Kumar Madhu , Alva Jayaprakash
Published: January 2013

We report the case of an adult male patient who was admitted to our hospital with a diagnosis of vivax malaria complicated with renal insufficiency and acute respiratory distress syndrome (ARDS). The patient was treated with intravenous artesunate. He was intubated and mechanically ventilated and taken up for haemodialysis in view of worsening renal parameters. He developed tachycardia a few hours later. ECG showed sinus tachycardia. Tachycardia persisted though the blood pressure was normal, there was no evidence of bleeding, and the heart was clinically normal. We tried to control the heart rate with diltiazem, adenosine and metoprolol but the tachycardia persisted. The heart rate was finally controlled with amiodarone. The patient improved, was weaned off from the ventilator and extubated. His renal functions gradually improved. Oral amiodarone was continued and there was no recurrence of tachycardia. We present this case to highlight the interesting association of vivax malaria with persistent, difficult to treat tachycardia.
Congenital familial myasthenic syndromes: disease and course in an affected dizygotic twin pair
Authors: Pavone Piero , Praticò Andrea Domenico , Pavone Vito , Falsaperla Raffaele
Published: January 2013

The present report describes clinical variability in an affected dizygotic twin pair. Twin 1 showed classical features of the congenital myasthenic syndromes (CMS), that is, ptosis, dysphonia, asthenia and hypotonia. In twin 2, these clinical signs were less pronounced, but subtle resulting in severe lumbar hyperlordosis. Molecular analysis, performed for both twins, revealed the presence of three polymorphisms in the heterozygous form in RAPSN gene. The present report highlights the clinical variability of the CMS.
A tale of two pelvises
Authors: Eisenstein Neil M
Published: January 2013

Two female doctors who were undergoing officer training at the Royal Military Academy Sandhurst sustained pubic ramus stress fractures. This report looks at the reasons why these medical officers may have sustained these fractures and how they may be prevented in future.
Osteosarcoma arising on a background of Paget's disease report of an unusual case
Authors: Qureshi Asim , Zahid Khawaja Farhan , Ibrahim Sinan Ismail , Burney Ikram
Published: January 2013

One of the serious complications of Paget's disease (PD) is a significant increase in the risk of developing osteosarcoma. Approximately 1% of the patients with PD develop osteosarcoma. This contributes significantly to the mortality and morbidity of the patients with PD. We present the case of an elderly person, who developed osteosarcoma 1 year after being diagnosed to have PD. The patient had been diagnosed to have lymphoma 8 years prior to the diagnosis of PD. The association between PD and follicular lymphoma is discussed.
Home-care nurses’ perceptions of unmet information needs and communication difficulties of older patients in the immediate post-hospital discharge period
Authors: Romagnoli Katrina M , Handler Steven M , Ligons Frank M , Hochheiser Harry
Published: January 2013

Objective

To understand home-care nurses’ perceptions of the post-hospitalisation information needs and communication problems of older patients, and how these factors might contribute to undesirable outcomes including poor patient reintegration into prior living environments and unplanned hospital readmissions.

Design

A ranked list of information needs experienced by patients was developed by two Nominal Group Technique (NGT) sessions from the perspective of home-care nurses. The list was combined with results from previously published work to develop a web-based survey administered to home-care nurses to elicit perceptions of patients’ post-hospitalisation information needs.

Results

Seventeen nurses participated in the NGT sessions, producing a list of 28 challenges grouped into five themes: medications, disease/condition, non-medication care/treatment/safety, functional limitations and communication problems. The survey was sent to 220 home-care nurses, with a 54.1% (119/220) response rate. Respondents identified several frequent, high-impact information and communication needs that have received little attention in readmission literature, including information about medication regimens; the severity of their condition; the hospital discharge management process; non-medication care regimens such as wound care, use of durable medical equipment and home safety; the extent of care needed; and which providers are best suited to provide that care. Responses also identified several communication difficulties that may play a role in readmissions.

Conclusions

Information needs and communication problems identified by home-care nurses expanded upon and reinforced results from prior studies. These results might be used to develop interventions that may improve information sharing among clinicians, patients and caregivers during care transitions to ensure patient reintegration into prior living environments, potentially preventing unplanned hospital readmissions.
Living with advanced cancer and an uncertain disease trajectory: an emerging patient population in palliative care?
Authors: Lobb Elizabeth A , Lacey Judith , Kearsley John , Liauw Winston , White Lesley , Hosie Annmarie
Published: January 2013

Objective

This study explored how patients diagnosed with advanced cancer cope with an uncertain disease trajectory.

Subjects

27 patients with advanced cancer and with a prognosis of 12 months or more were recruited from the medical/radiation oncology and palliative care service at three metropolitan hospitals.

Methods

A semistructured face-to-face interview was conducted. Interviews were audio-taped and transcribed verbatim. Data analysis was based on Grounded Theory using the constant comparison method.

Results

Results indicate that patients cope by avoidance, remaining positive, maintaining as normal a life as possible, minimising the impact of the disease on their daily lives, comparing themselves favourably with others in a similar situation and focusing on the outcome of treatment to control disease progression. Most did not wish to discuss prognosis or have detailed information on disease progression.

Conclusions

Participants in this study represent an emerging cancer patient population who are receiving palliative therapies. While they have incurable cancer, they self-report as clinically well, they describe a good quality of life and the trajectory of their disease, while unpredictable, may extend over many months to years. Our study suggests that a flexible model of care is needed to support the needs of people who may still be receiving some form of chemotherapy and/or radiotherapy, and remain well. This model may need to take more of an intermittent approach, that is, as required for specific symptom management, rather than patients being linked continuously to a palliative care service for long periods of time.
In situ time-resolved X-ray diffraction study of the synthesis of Mo2C with different carburization agents
Authors: Guzmán Héctor J. , Xu Wenqian , Stacchiola Dario , Vitale Gerardo , Scott Carlos E. , Rodríguez José A. , Pereira-Almao Pedro
Published: January 2013

Toluene, n-heptane, and methane were studied as carbon sources during the synthesis of Mo2C. Ammonium heptamolybdate ((NH4)6Mo7O24·4H2O), molybdenum dioxide (MoO2), orthorhombic molybdenum trioxide (α-MoO3), and a low crystallinity molybdenum oxide (MoOx) were employed as metal precursors and their conversion into the carbide phase was followed by time-resolved X-ray diffraction from synchrotron radiation. Thermal treatment was carried out from 298 K up to 1023 K and the evolution of gases analyzed by mass spectrometry. The resulting carbidic phase obtained using methane/H2 was hexagonal β-Mo2C, while in contrast, cubic molybdenum carbide (α-MoC1–x) was obtained when toluene/H2 or n-heptane/H2 were employed, which occurred independently of the original metal precursor. Molybdenum carbide was first detected, on average, at about 923 K. Mass spectrometry results show the formation of CO when methane was used as a carbon source, while methyl radicals and benzene and mainly methyl radicals were detected when toluene and n-heptane were employed, respectively.
Effects of column stiffness irregularity on the seismic response of bridges in the longitudinal direction
Authors: Tehrani Payam , Mitchell Denis
Published: January 2013

The longitudinal seismic responses of 4-span continuous bridges designed based on the 2006 Canadian Highway Bridge Design Code were studied using elastic response spectrum and inelastic time-history analyses. Several boundary conditions including unrestrained horizontal movements at the abutments and different abutment stiffnesses were considered in the nonlinear analyses. The seismic response of more than 2600 bridges were studied to determine the effects of different design and modelling parameters including the effects of different column heights, column diameters, and superstructure mass as well as different abutment stiffnesses. The bridges were designed using two different force modification factors of 3 and 5. The effects of column stiffness ratios on the elastic and inelastic analysis results, maximum ductility demands, concentration of ductility demands, and demand to capacity ratios were investigated. The results indicate that the seismic response and maximum ductility demands in the longitudinal direction are influenced by important parameters such as the total stiffness of the substructure, the column stiffness ratio, and the aspect ratio of the columns.
Important open-ocean areas for northern Atlantic salmon (Salmo salar) — as estimated using a simple ambient-temperature approach
Authors: Chittenden Cedar M. , Fauchald Per , Rikardsen Audun H.
Published: January 2013

Tracking salmon migratory behaviour in the open ocean has been a challenge to researchers. As the marine phase essentially determines the size and survival of individuals and populations, it is arguably the most influential life cycle period for salmon population dynamics. Thus, methods providing an understanding of the spatial and temporal patterns of salmon marine migratory behaviour could improve the species' management and conservation. A model was developed that correlated temperature data from archival tags with sea-surface temperatures (SSTs) to identify the probable marine feeding areas of a northeastern Atlantic salmon (Salmo salar) population over 3 years. The marine distribution of the tagged population extended from the Greenland Sea, north to Svalbard, and into the eastern Barents Sea. Higher probability occupancy zones overlapped with the polar front area from September to April during all 3 years. While the migratory behaviour appeared similar between years and seasons, the fish were distributed farther south and west during the autumn of 2007 than during the autumns of 2006 and 2008. This may have been related to warmer summer SSTs and an earlier annual maximum SST. The ambient-temperature approach developed here is a cost-effective way to monitor the open-ocean migratory patterns of surface-oriented marine fishes.