bluuebunny/crossref_metadata_2025_split huggingface dataset:
The importance of colonization pressure in multiresistant Acinetobacter baumannii acquisition in a Greek intensive care unit
Authors: Arvaniti Kostoula , Lathyris Dimitrios , Ruimy Raymond , Haidich Anna-Bettina , Koulourida Vasiliki , Nikolaidis Pavlos , Matamis Dimitrios , Miyakis Spiros 
Published: June 2012

Abstract
Introduction
We investigated the role of colonization pressure on multiresistant Acinetobacter baumannii acquisition and defined patient-related predictors for carriage at admission and acquisition during hospitalization in intensive care unit (ICU) patients.

Methods
This was a 12-month, prospective, cohort study of all patients admitted to a single ICU of a tertiary hospital. Screening samples were collected at ICU admission to identify imported carriers, and weekly during hospitalization to identify acquisition. Colonization pressure (carriers' patient-days × 100/all patients' patient-days) and the absolute number of carriers were calculated weekly, and the statistical correlation between these parameters and acquisition was explored. Multivariable analysis was performed to identify predictors for A. baumannii carriage at admission and acquisition during hospitalization. A. baumannii isolates were genotyped by repetitive-extragenic-palindromic polymerase chain reaction (PCR; rep-PCR).

Results
At ICU admission, 284 patients were screened for carriage. A. baumannii was imported in 16 patients (5.6%), and acquisition occurred in 32 patients (15.7%). Acquisition was significantly correlated to weekly colonization pressure (correlation coefficient, 0.379; P = 0.004) and to the number of carriers per week (correlation coefficient, 0.499; P < 0.001). More than one carrier per week significantly increased acquisition risk (two to three carriers, odds ratio (OR), 12.66; P = 0.028; more than four carriers, OR, 25.33; P = 0.004). Predictors of carriage at admission were infection at admission (OR, 11.03; confidence interval (CI), 3.56 to 34.18; P < 0.01) and hospitalization days before ICU (OR, 1.09; CI, 1.01 to 1.16; P = 0.02). Predictors of acquisition were a medical reason for ICU admission (OR, 5.11; CI, 1.31 to 19.93; P = 0.02), duration of antibiotic administration in the unit (OR, 1.24; CI, 1.12 to 1.38; P < 0.001), and duration of mechanical ventilation (OR, 1.08; CI, 1.04 to 1.13; P = 0.001). All strains were multiresistant. Rep-PCR analysis showed one dominant cluster.

Conclusions
Acquisition of multiresistant A. baumannii in ICU patients is strongly correlated to colonization pressure. High levels of colonization pressure and more than two carriers per week independently increase acquisition risk. Patient-related factors, such as infection at admission and long hospitalization before the ICU, can identify imported A. baumannii carriers. Medical patients with extended administration of antibiotics and long duration of mechanical ventilation in the ICU were the most vulnerable to acquisition.
Should lower respiratory tract secretions from intensive care patients be systematically screened for influenza virus during the influenza season?
Authors: Giannella Maddalena , Rodríguez-Sánchez Belen , Roa Paula López , Catalán Pilar , Muñoz Patricia , de Viedma Darío García , Bouza Emilio ,   the Gregorio Marañón Task Force for Pneumonia (GANG)
Published: June 2012

Abstract
Introduction
Influenza is easily overlooked in intensive care units (ICUs), particularly in patients with alternative causes of respiratory failure or in those who acquire influenza during their ICU stay.

Methods
We performed a prospective study of patients admitted to three adult ICUs of our hospital from December 2010 to February 2011. All tracheal aspirate (TA) samples sent to the microbiology department were systematically screened for influenza. We defined influenza as unsuspected if testing was not requested and the patient was not receiving empirical antiviral therapy after sample collection.

Results
We received TA samples from 105 patients. Influenza was detected in 31 patients and was classified as unsuspected in 15 (48.4%) patients, and as hospital acquired in 13 (42%) patients. Suspected and unsuspected cases were compared, and significant differences were found for age (53 versus 69 median years), severe respiratory failure (68.8% versus 20%), surgery (6.3% versus 60%), median days of ICU stay before diagnosis (1 versus 4), nosocomial infection (18.8% versus 66.7%), cough (93.8% versus 53.3%), localized infiltrate on chest radiograph (6.3% versus 40%), median days to antiviral treatment (2 versus 9), pneumonia (93.8% versus 53.3%), and acute respiratory distress syndrome (75% versus 26.7%). Multivariate analysis showed admission to the surgical ICU (odds ratio (OR), 37.1; 95% confidence interval (CI), 2.1 to 666.6; P = 0.01) and localized infiltrate on chest radiograph (OR, 27.8; 95% CI, 1.3 to 584.1; P = 0.03) to be independent risk factors for unsuspected influenza. Overall mortality at 30 days was 29%. ICU admission for severe respiratory failure was an independent risk factor for poor outcome.

Conclusion
During the influenza season, almost one third of critical patients with suspected lower respiratory tract infection had influenza, and in 48.4%, the influenza was unsuspected. Lower respiratory samples from adult ICUs should be systematically screened for influenza during seasonal epidemics.
Assessment of candidemia-attributable mortality in critically ill patients using propensity score matching analysis
Authors: González de Molina Francisco J , León Cristóbal , Ruiz-Santana Sergio , Saavedra Pedro ,   the CAVA I Study Group
Published: June 2012

Abstract
Introduction
Candidemia in critically ill patients is usually a severe and life-threatening condition with a high crude mortality. Very few studies have focused on the impact of candidemia on ICU patient outcome and attributable mortality still remains controversial. This study was carried out to determine the attributable mortality of ICU-acquired candidemia in critically ill patients using propensity score matching analysis.

Methods
A prospective observational study was conducted of all consecutive non-neutropenic adult patients admitted for at least seven days to 36 ICUs in Spain, France, and Argentina between April 2006 and June 2007. The probability of developing candidemia was estimated using a multivariate logistic regression model. Each patient with ICU-acquired candidemia was matched with two control patients with the nearest available Mahalanobis metric matching within the calipers defined by the propensity score. Standardized differences tests (SDT) for each variable before and after matching were calculated. Attributable mortality was determined by a modified Poisson regression model adjusted by those variables that still presented certain misalignments defined as a SDT > 10%.

Results
Thirty-eight candidemias were diagnosed in 1,107 patients (34.3 episodes/1,000 ICU patients). Patients with and without candidemia had an ICU crude mortality of 52.6% versus 20.6% (P < 0.001) and a crude hospital mortality of 55.3% versus 29.6% (P = 0.01), respectively. In the propensity matched analysis, the corresponding figures were 51.4% versus 37.1% (P = 0.222) and 54.3% versus 50% (P = 0.680). After controlling residual confusion by the Poisson regression model, the relative risk (RR) of ICU- and hospital-attributable mortality from candidemia was RR 1.298 (95% confidence interval (CI) 0.88 to 1.98) and RR 1.096 (95% CI 0.68 to 1.69), respectively.

Conclusions
ICU-acquired candidemia in critically ill patients is not associated with an increase in either ICU or hospital mortality.
Flow structure and transport characteristics of feeding and exchange currents generated by upside-down Cassiopea jellyfish
Authors: Santhanakrishnan Arvind , Dollinger Makani , Hamlet Christina L. , Colin Sean P. , Miller Laura A. 
Published: June 2012

SUMMARY
Quantifying the flows generated by the pulsations of jellyfish bells is crucial for understanding the mechanics and efficiency of their swimming and feeding. Recent experimental and theoretical work has focused on the dynamics of vortices in the wakes of swimming jellyfish with relatively simple oral arms and tentacles. The significance of bell pulsations for generating feeding currents through elaborate oral arms and the consequences for particle capture are not as well understood. To isolate the generation of feeding currents from swimming, the pulsing kinematics and fluid flow around the benthic jellyfish Cassiopea spp. were investigated using a combination of videography, digital particle image velocimetry and direct numerical simulation. During the rapid contraction phase of the bell, fluid is pulled into a starting vortex ring that translates through the oral arms with peak velocities that can be of the order of 10 cm s–1. Strong shear flows are also generated across the top of the oral arms throughout the entire pulse cycle. A coherent train of vortex rings is not observed, unlike in the case of swimming oblate medusae such as Aurelia aurita. The phase-averaged flow generated by bell pulsations is similar to a vertical jet, with induced flow velocities averaged over the cycle of the order of 1–10 mm s–1. This introduces a strong near-horizontal entrainment of the fluid along the substrate and towards the oral arms. Continual flow along the substrate towards the jellyfish is reproduced by numerical simulations that model the oral arms as a porous Brinkman layer of finite thickness. This two-dimensional numerical model does not, however, capture the far-field flow above the medusa, suggesting that either the three-dimensionality or the complex structure of the oral arms helps to direct flow towards the central axis and up and away from the animal.
Body size is not critical for criticalPO2 in scarabaeid and tenebrionid beetles
Authors: Lease Hilary M. , Klok Cornelis J. , Kaiser Alexander , Harrison Jon F. 
Published: June 2012

SUMMARYConstraints on oxygen delivery potentially limit animal body size. Because diffusion rates are highly distance dependent, and because tracheal length increases with size, gas exchange was traditionally thought to be more difficult for larger insects. As yet the effect of body size on critical oxygen partial pressure (Pcrit) has not been measured for any clade of insect species for which there are interspecific data on tracheal scaling. We addressed this deficiency by measuring Pcrit over a 4150-fold mass range (ratio of largest to smallest species mean) of two families of Coleoptera (Tenebrionidae and Scarabaeidae). We exposed adult beetles to progressively lower oxygen levels and measured their ability to maintain CO2 release rates. Absolute metabolic rates increased hypometrically with beetle body mass (M) at both normoxic (M0.748) and hypoxic (M0.846) conditions. Pcrit, however, was independent of body size. Maximum overall conductances for oxygen from air to mitochondria (GO2,max) matched metabolic rates as insects became larger, likely enabling the similar Pcrit values observed in large and small beetles. These data suggest that current atmospheric oxygen levels do not limit body size of insects because of limitations on gas exchange. However, increasing relative investment in the tracheal system in larger insects may produce trade-offs or meet spatial limits that constrain insect size.
Metabolism in the age of ‘omes’
Authors: Suarez Raul K. , Moyes Christopher D. 
Published: June 2012

SummaryMuch research in comparative physiology is now performed using ‘omics’ tools and many results are interpreted in terms of the effects of changes in gene expression on energy metabolism. However, ‘metabolism’ is a complex phenomenon that spans multiple levels of biological organization. In addition rates and directions of flux change dynamically under various physiological circumstances. Within cells, message level cannot be equated with protein level because multiple mechanisms are at play in the ‘regulatory hierarchy’ from gene to mRNA to enzyme protein. This results in many documented instances wherein change in mRNA levels and change in enzyme levels are unrelated. It is also known from metabolic control analysis that the influence of single steps in pathways on flux is often small. Flux is a system property and its control tends to be distributed among multiple steps. Consequently, change in enzyme levels cannot be equated with change in flux. Approaches developed by Hans Westerhoff and colleagues, called ‘hierarchical regulation analysis’, allow quantitative determination of the extent to which ‘hierarchical regulation’, involving change in enzyme level, and ‘metabolic regulation’, involving the modulation of the activity of preexisting enzyme, regulate flux. We outline these approaches and provide examples to show their applicability to problems of interest to comparative physiologists.
Acclimatization of seasonal energetics in northern cardinals (Cardinalis cardinalis) through plasticity of metabolic rates and ceilings
Authors: Sgueo Carrie , Wells Marion E. , Russell David E. , Schaeffer Paul J. 
Published: June 2012

SUMMARY
Northern cardinals (Cardinalis cardinalis) are faced with energetically expensive seasonal challenges that must be met to ensure survival, including thermoregulation in winter and reproductive activities in summer. Contrary to predictions of life history theory that suggest breeding metabolic rate should be the apex of energetic effort, winter metabolism exceeds that during breeding in several temperate resident bird species. By examining whole-animal, tissue and cellular function, we ask whether seasonal acclimatization is accomplished by coordinated phenotypic plasticity of metabolic systems. We measured summit metabolism (V̇O2,sum), daily energy expenditure (DEE) and muscle oxidative capacity under both winter (December to January) and breeding (May to June) conditions. We hypothesize that: (1) rates of energy utilization will be highest in the winter, contrary to predictions based on life history theory, and (2) acclimatization of metabolism will occur at multiple levels of organization such that birds operate with a similar metabolic ceiling during different seasons. We measured field metabolic rates using heart rate telemetry and report the first daily patterns in avian field metabolic rate. Patterns of daily energy use differed seasonally, primarily as birds maintain high metabolic rates throughout the winter daylight hours. We found that DEE and V̇O2,sum were significantly greater and DEE occurred at a higher fraction of maximum metabolic capacity during winter, indicating an elevation of the metabolic ceiling. Surprisingly, there were no significant differences in mass or oxidative capacity of skeletal muscle. These data, highlighting the importance of examining energetic responses to seasonal challenges at multiple levels, clearly reject life history predictions that breeding is the primary energetic challenge for temperate zone residents. Further, they indicate that metabolic ceilings are seasonally flexible as metabolic effort during winter thermoregulation exceeds that of breeding.
Blowfly flight characteristics are shaped by environmental features and controlled by optic flow information
Authors: Kern Roland , Boeddeker Norbert , Dittmar Laura , Egelhaaf Martin 
Published: June 2012

SUMMARYBlowfly flight consists of two main components, saccadic turns and intervals of mostly straight gaze direction, although, as a consequence of inertia, flight trajectories usually change direction smoothly. We investigated how flight behavior changes depending on the surroundings and how saccadic turns and intersaccadic translational movements might be controlled in arenas of different width with and without obstacles. Blowflies do not fly in straight trajectories, even when traversing straight flight arenas; rather, they fly in meandering trajectories. Flight speed and the amplitude of meanders increase with arena width. Although saccade duration is largely constant, peak angular velocity and succession into either direction are variable and depend on the visual surroundings. Saccade rate and amplitude also vary with arena layout and are correlated with the ‘time-to-contact’ to the arena wall. We provide evidence that both saccade and velocity control rely to a large extent on the intersaccadic optic flow generated in eye regions looking well in front of the fly, rather than in the lateral visual field, where the optic flow at least during forward flight tends to be strongest.
A unique alkaline pH-regulated and fatty acid-activated tandem pore domain potassium channel (K2P) from a marine sponge
Authors: Wells Gregory D. , Tang Qiong-Yao , Heler Robert , Tompkins-MacDonald Gabrielle J. , Pritchard Erica N. , Leys Sally P. , Logothetis Diomedes E. , Boland Linda M. 
Published: June 2012

SUMMARY
A cDNA encoding a potassium channel of the two-pore domain family (K2P, KCNK) of leak channels was cloned from the marine sponge Amphimedon queenslandica. Phylogenetic analysis indicated that AquK2P cannot be placed into any of the established functional groups of mammalian K2P channels. We used the Xenopus oocyte expression system, a two-electrode voltage clamp and inside-out patch clamp electrophysiology to determine the physiological properties of AquK2P. In whole cells, non-inactivating, voltage-independent, outwardly rectifying K+ currents were generated by external application of micromolar concentrations of arachidonic acid (AA; EC50 ∼30 μmol l–1), when applied in an alkaline solution (≥pH 8.0). Prior activation of channels facilitated the pH-regulated, AA-dependent activation of AquK2P but external pH changes alone did not activate the channels. Unlike certain mammalian fatty-acid-activated K2P channels, the sponge K2P channel was not activated by temperature and was insensitive to osmotically induced membrane distortion. In inside-out patch recordings, alkalinization of the internal pH (pKa 8.18) activated the AquK2P channels independently of AA and also facilitated activation by internally applied AA. The gating of the sponge K2P channel suggests that voltage-independent outward rectification and sensitivity to pH and AA are ancient and fundamental properties of animal K2P channels. In addition, the membrane potential of some poriferan cells may be dynamically regulated by pH and AA.
Conditioned response to a magnetic anomaly in the Pekin duck (Anas platyrhynchos domestica) involves the trigeminal nerve
Authors: Freire Rafael , Dunston Emma , Fowler Emmalee M. , McKenzie Gary L. , Quinn Christopher T. , Michelsen Jacob 
Published: June 2012

SUMMARY
There have been recent calls to develop protocols that collect unambiguous measures of behaviour using automatic techniques in conditioning experiments on magnetic orientation. Here, we describe an automated technique for recording the behaviour of Pekin ducks in a conditioning test that allows them to express unrestricted searching behaviour. Pekin ducks were trained to find hidden food in one corner of a square arena below which was placed a magnetic coil that produced a local magnetic anomaly. The trigeminal nerve was anaesthetised by injection of lignocaine hydrochloride 2–3 mm caudal to the medial canthus of each eye, medial to the globe, prior to the presentation of unrewarded tests. Lignocaine-treated ducks showed no initial preference for the magnetic anomaly whereas saline-treated control ducks showed a significant preference at the same age. A second experiment was undertaken in which the trigeminal nerve was surgically severed and 2–3 mm removed, and this surgery abolished the previously observed preference for the corner with the magnetic coil in a small number of ducks. These data show that Pekin ducks are able to detect and use magnetic stimuli to guide unrestricted search behaviour and are consistent with a hypothesis of magnetoreception involving a putative cluster of magnetite in the upper beak.
Directional cues inDrosophila melanogasteraudition: structure of acoustic flow and inter-antennal velocity differences
Authors: Morley Erica L. , Steinmann Thomas , Casas Jérôme , Robert Daniel 
Published: June 2012

SUMMARYDrosophila melanogaster have bilateral antisymmetric antennae that receive the particle velocity component of an acoustic stimulus. Acoustic communication is important in their courtship, which takes place in the acoustic near-field. Here, the small size of the dipole sound source (the male wing) and the rapid attenuation rate of particle velocity produce a spatially divergent sound field with highly variable magnitude. Also, male and female D. melanogaster are not usually stationary during courtship, resulting in a variable directionality of the acoustic stimulus. Using both particle image velocimetry and laser Doppler vibrometry, we examined the stimulus flow around the head of D. melanogaster to identify the actual geometry of the acoustic input to the antennae and its directional response. We reveal that the stimulus changes in both magnitude and direction as a function of its angle of incidence. Remarkably, directionality is substantial, with inter-antennal velocity differences of 25 dB at 140 Hz. For an organism whose auditory receivers are separated by only 660±51 μm (mean ± s.d.), this inter-antennal velocity difference is far greater than differences in intensity observed between tympanal ears for organisms of similar scale. Further, the mechanical sensitivity of the antennae changes as a function of the angle of incidence of the acoustic stimulus, with peak responses along axes at 45 and 315 deg relative to the longitudinal body axis. This work indicates not only that the flies are able to detect differential cues in signal direction, but also that the male song structure may not be the sole determinant of mating success; his spatial positioning is also crucial to female sound reception and therefore also perhaps to her decision making.
Decreased expression of adipose CD36 and FATP1 are associated with increased plasma non-esterified fatty acids during prolonged fasting in northern elephant seal pups (Mirounga angustirostris)
Authors: Viscarra Jose Abraham , Vázquez-Medina José Pablo , Rodriguez Ruben , Champagne Cory D. , Adams Sean H. , Crocker Daniel E. , Ortiz Rudy M. 
Published: June 2012

SUMMARY
The northern elephant seal pup (Mirounga angustirostris) undergoes a 2–3 month post-weaning fast, during which it depends primarily on the oxidation of fatty acids to meet its energetic demands. The concentration of non-esterified fatty acids (NEFAs) increases and is associated with the development of insulin resistance in late-fasted pups. Furthermore, plasma NEFA concentrations respond differentially to an intravenous glucose tolerance test (ivGTT) depending on fasting duration, suggesting that the effects of glucose on lipid metabolism are altered. However, elucidation of the lipolytic mechanisms including lipase activity during prolonged fasting in mammals is scarce. To assess the impact of fasting and glucose on the regulation of lipid metabolism, adipose tissue and plasma samples were collected before and after ivGTTs performed on early (2 weeks, N=5) and late (6–8 weeks; N=8) fasted pups. Glucose administration increased plasma triglycerides and NEFA concentrations in late-fasted seals, but not plasma glycerol. Fasting decreased basal adipose lipase activity by 50%. Fasting also increased plasma lipase activity twofold and decreased the expressions of CD36, FAS, FATP1 and PEPCK-C by 22–43% in adipose tissue. Plasma acylcarnitine profiling indicated that late-fasted seals display higher incomplete LCFA β-oxidation. Results suggest that long-term fasting induces shifts in the regulation of lipolysis and lipid metabolism associated with the onset of insulin resistance in northern elephant seal pups. Delineation of the mechanisms responsible for this shift in regulation during fasting can contribute to a more thorough understanding of the changes in lipid metabolism associated with dyslipidemia and insulin resistance in mammals.