bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving first‐time donor attendance rates through the use of enhanced donor preparation materials
Authors: Masser Barbara , France Christopher R. , Foot Jayne , Rozsa Amy , Hayman Jane , Waller Daniel , Hunder Everard
Published: February 2016

BACKGROUND

Many nondonors are positive about blood donation and this motivates booking an appointment to donate. However, as their appointment approaches barriers to donating—such as anxiety—may become salient and deter attendance. Building on research of France and colleagues demonstrating the positive effect of enhanced preparation materials on donor recruitment, this study sought to determine whether these materials could effectively boost first donation appointment attendance.

STUDY DESIGN AND METHODS

A field study comprising a 3 (brochure: none, e‐mail, hard copy) × 2 (national call center [NCC] contact: none, call) between‐subjects design was conducted with 3646 nondonors who had scheduled their first appointment. Participants in the brochure conditions received either a hard copy or an e‐mailed link to electronic materials modeled on the donor preparation research of France and colleagues. Participants in the NCC call condition also received a call scripted in line with these preparation materials. The key outcome was new donor attendance rate.

RESULTS

Although first‐appointment attendance rates were high in the control (no additional contact) condition at 85.07% of those not canceling in advance, dual exposure to the preparation materials through a NCC call and an electronic brochure boosted attendance. The relative risk of attending in the NCC call and electronic brochure condition was 1.0836 (95% confidence interval, 1.0352‐1.1343; p = 0.0006), with attendance 8.36% higher than in the control. This gain in attendance came at a relative increase in recruitment costs of 2%.

CONCLUSION

The use of tailored communication to address new donors' concerns and prepare them for donating bolsters attendance rates.
Blood donation and risk of polycythemia vera
Authors: Edgren Gustaf , Nyrén Olof , Hultcrantz Malin , Nielsen Kaspar Rene , Pedersen Ole B.V. , Björkholm Magnus , Rostgaard Klaus , Hjalgrim Henrik
Published: February 2016

BACKGROUND

It has been suggested that blood donors could have an increased risk of polycythemia vera (PV). However, no study has assessed whether frequent donors have a higher PV risk than less frequent donors.

STUDY DESIGN AND METHODS

From the Scandinavian Donations and Transfusions (SCANDAT2) database, we established a cohort of blood donors who had donated whole blood at least once between 1980 and 2012. Within this cohort we first assessed the risk of PV, comparing the donors to the general population using standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (CIs). To assess the association between frequency of blood donation and risk of PV we then conducted a case‐control study nested within the cohort, where we compared prior donation activity among donors who were diagnosed with PV and matched controls. Here odds ratios (ORs) were used as measures of relative risk comparing donors with different donation frequency.

RESULTS

Among 1.4 million donors in the cohort a total of 271 donors developed PV, yielding a SIR of 1.00 (95% CI, 0.89‐1.13) compared to the general population. The nested case‐control study showed no association between donation frequency and risk of PV. The OR of PV comparing donors who had made at least 33 donations in the period from 3 to 22 years before diagnosis of the case, to donors with one to eight donations in the same period was 1.01 (95% CI, 0.51‐1.97).

CONCLUSIONS

We find no evidence of excess risk of PV among blood donors or of an association between donation frequency and PV risk.
Comparative effects of different types of tank‐mixed adjuvants on the efficacy, absorption and translocation of cyhalofop‐butyl in barnyardgrass (Echinochloa crus‐galli [L.] Beauv.)
Authors: Li Jing , Chen Weitao , Xu Yong , Wu Xuemin
Published: February 2016

The efficacy of cyhalofop‐butyl with tank‐mixed adjuvants on barnyardgrass (Echinochloa crus‐galli [L.] Beauv.), as well as the physico‐chemical properties, absorption and translocation, was evaluated and compared. The efficacy experiment showed that the treatments with tank‐mixed adjuvants were approximately twofold more effective than with cyhalofop‐butyl alone at 2% (v/v) (silwet 625 at 0.05%). The surface tension decreased and the droplets could spread automatically on the leaves after adding the adjuvants. The spreading speed increased significantly with the adjuvants. The epidermal cells and wax layer were damaged by the adjuvants. The absorption of cyhalofop‐butyl was increased significantly after adding the tank‐mixed adjuvants. GY‐T12 and silwet 625 were conducive to upward translocation and all six tank‐mixed adjuvants promoted the downward translocation of the herbicide. The results demonstrate that adjuvants can have a considerable influence on the efficiency of cyhalofop‐butyl on barnyardgrass.
Seasonal dynamics of ground cover in Cirsium arvense – a basis for estimating grazing losses and economic impacts
Authors: Bourdôt G W , Hurrell G A , Trolove M , Saville D J
Published: February 2016

Analysis of the economics of managing Cirsium arvense in grazed pastures worldwide has been hampered by a lack of data on the within‐year seasonal dynamics of the weed and its impact on the yield of palatable herbage. To redress this, the seasonal pattern in within‐patch percentage ground cover of the weed was determined from measurements on 39 dairy and 66 sheep and/or beef cattle farms in New Zealand during 2009–2010 and 2010–2011. This pattern was then scaled using farmer estimates of peak whole‐farm cover to derive mean monthly covers for dairy, beef, sheep/beef, sheep and deer farms. These monthly covers corresponded, respectively, to mean annual percentage covers of 2.7, 1.7, 3.0, 5.9 and 2.9% and to mean annual percentage losses in pasture growth (palatable herbage yield) of 3.6, 2.3, 4.0, 7.8 and 3.9%. The latter, in combination with 2011–2012 farm statistics, revealed that C. arvense caused a national loss in pastoral farm gross revenue in New Zealand in 2011–2012 of $685 million ($446 m dairy, $233 m sheep/beef, $6 m deer). Beyond the scope of this paper, the monthly covers and their corresponding monthly losses in pasture growth provide a basis for modelling the economic impacts of C. arvense and its management at a farm scale. More generally, the analytical method that we have developed is appropriate for evaluating the economic impact of any weed in a grazed pasture, particularly those exhibiting pronounced seasonal patterns in occupancy, such as annuals and deciduous perennials.
Comparative study of quality of life and psychosocial characteristics in patients with psoriasis and leg ulcers
Authors: Kouris Anargyros , Christodoulou Christos , Efstathiou Vasiliki , Tsatovidou Revekka , Torlidi‐Kordera Evangelia , Zouridaki Eftychia , Kontochristopoulos George
Published: February 2016

Psoriasis and leg ulcers have a marked impact on the patient's quality of life and represent a life‐long burden for affected patients. The aim of this study is to compare the quality of life, anxiety and depression, self‐esteem, and loneliness in patients with psoriasis and leg‐ulcer patients. Eighty patients with leg ulcers, eighty patients with psoriasis, and eighty healthy controls were included in this study. The quality of life, depression and anxiety, loneliness of the patient, and self‐esteem were assessed using the Dermatology Life Quality Index (DLQI), Hospital Anxiety and Depression Scale (HADS), the UCLA loneliness Scale (UCLA‐Version 3), and the Rosenberg's Self‐esteem Scale (RSES), respectively. The DLQI score among patients with psoriasis was 12.74 ± 4.89 and leg ulcer patients was 13.28 ± 2.57. The patients with psoriasis presented statistically significant higher anxiety (9.87 ± 4.56) than both leg ulcer patients (8.26 ± 2.82) and controls (6.45 ± 1.89), while leg ulcer patients also presented higher anxiety than controls. Regarding self‐esteem, although there were no significant differences between the patients with psoriasis (15.25 ± 3.20) and the ones with leg ulcers (15.89 ± 2.93), they both presented statistically significant lower self‐esteem scores than control group (18.53 ± 3.04). The patients with psoriasis presented statistically significant higher levels of loneliness and social isolation (46.18 ± 6.63) compared to leg ulcer patients (43.73 ± 5.68) than controls (42.49 ± 3.41). Psoriasis and leg ulcers are long‐term skin diseases associated with significant impairment of the patient's quality of life, anxiety, and self‐esteem, which are frequently under‐recognized.
Effects of tretinoin on wound healing in aged skin
Authors: de Campos Peseto Danielle , Carmona Erica Vilaça , Silva Kellyn Cristina da , Guedes Flavia Roberta Valente , Hummel Filho Fernando , Martinez Natalia Peres , Pereira José Aires , Rocha Thalita , Priolli Denise Gonçalves
Published: February 2016

Aged and adult populations have differences in the structural, biological, and healing properties of skin. Comparative studies of healing under the influence of retinoids in both these populations are very important and, to the best of our knowledge, have not been performed to date. The purpose of this study was to compare the activities of topical tretinoin in aged and adult animal models of wound healing by secondary intention. Male aged rats (24 months old, n = 7) and adult rats (6 months old, n = 8) were used. The rats were assigned to the following groups according to the dates on which wound samples were excised (day 14 or 21 after model creation): treated group, control group, and naive group. Topical application of tretinoin cream was used only on the proximal wound and was applied daily for 7 days. Wound healing areas were measured using metal calipers, and morphological analysis was performed. Slides were stained with Hematoxylin and Eosin, Masson's trichrome, and periodic acid‐Schiff stains. Statistical analysis adopted a 5% coefficient for rejection of the null hypothesis. Although aged animals showed skin repair, complete reepithelialization was found on day 21 in some animals of both groups (treated and control). In aged rats, the wound area was significantly smaller in treated wounds than in untreated wounds, resulting in a larger scar area compared with the adult group. When treated wounds were compared, no differences were found between the wound areas in adult and aged rats. As expected, the collagen concentration was higher in normal skin from adult rats than in normal skin from aged animals, but there was no difference when aged skin was treated with tretinoin. These results indicate that tretinoin increases collagen synthesis in aged skin and returns the healing process to a normal state of skin healing.
Inositol 1,4,5‐trisphosphate receptors and their protein partners as signalling hubs
Authors: Prole David L. , Taylor Colin W.
Published: February 2016

Inositol 1,4,5‐trisphosphate receptors (IP3Rs) are expressed in nearly all animal cells, where they mediate the release of Ca2+ from intracellular stores. The complex spatial and temporal organization of the ensuing intracellular Ca2+ signals allows selective regulation of diverse physiological responses. Interactions of IP3Rs with other proteins contribute to the specificity and speed of Ca2+ signalling pathways, and to their capacity to integrate information from other signalling pathways. In this review, we provide a comprehensive survey of the proteins proposed to interact with IP3Rs and the functional effects that these interactions produce. Interacting proteins can determine the activity of IP3Rs, facilitate their regulation by multiple signalling pathways and direct the Ca2+ that they release to specific targets. We suggest that IP3Rs function as signalling hubs through which diverse inputs are processed and then emerge as cytosolic Ca2+ signals.

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Corticospinal excitability is associated with hypocapnia but not changes in cerebral blood flow
Authors: Hartley Geoffrey L. , Watson Cody L. , Ainslie Philip N. , Tokuno Craig D. , Greenway Matthew J. , Gabriel David A. , O'Leary Deborah D. , Cheung Stephen S.
Published: February 2016

Key points

Reductions in cerebral blood flow (CBF) may be implicated in the development of neuromuscular fatigue; however, the contribution from hypocapnic‐induced reductions (i.e. ) in CBF versus reductions in CBF per se has yet to be isolated.

We assessed neuromuscular function while using indomethacin to selectively reduce CBF without changes in and controlled hyperventilation‐induced hypocapnia to reduce both CBF and .

Increased corticospinal excitability appears to be exclusive to reductions in but not reductions in CBF, whereas sub‐optimal voluntary output from the motor cortex is moderately associated with decreased CBF independent of changes in .

These findings suggest that changes in CBF and have distinct roles in modulating neuromuscular function.

Although reductions in cerebral blood flow (CBF) may be involved in central fatigue, the contribution from hypocapnia‐induced reductions in CBF versus reductions in CBF per se has not been isolated. This study examined whether reduced arterial (), independent of concomitant reductions in CBF, impairs neuromuscular function. Neuromuscular function, as indicated by motor‐evoked potentials (MEPs), maximal M‐wave (Mmax) and cortical voluntary activation (cVA) of the flexor carpi radialis muscle during isometric wrist flexion, was assessed in ten males (29 ± 10 years) during three separate conditions: (1) cyclooxygenase inhibition using indomethacin (Indomethacin, 1.2 mg kg−1) to selectively reduce CBF by 28.8 ± 10.3% (estimated using transcranial Doppler ultrasound) without changes in end‐tidal (); (2) controlled iso‐oxic hyperventilation‐induced reductions in (Hypocapnia),  = 30.1 ± 4.5 mmHg with related reductions in CBF (21.7 ± 6.3%); and (3) isocapnic hyperventilation (Isocapnia) to examine the potential direct influence of hyperventilation‐mediated activation of respiratory control centres on CBF and changes in neuromuscular function. Change in MEP amplitude (%Mmax) from baseline was greater in Hypocapnia tha in Isocapnia (11.7 ± 9.8%, 95% confidence interval (CI) [2.6, 20.7], P = 0.01) and Indomethacin (13.3 ± 11.3%, 95% CI [2.8, 23.7], P = 0.01) with a large Cohen's effect size (d ≥ 1.17). Although not statistically significant, cVA was reduced with a moderate effect size in Indomethacin (d = 0.7) and Hypocapnia (d = 0.9) compared to Isocapnia. In summary, increased corticospinal excitability – as reflected by larger MEP amplitude – appears to be exclusive to reduced , but not reductions in CBF per se. Sub‐optimal voluntary output from the motor cortex is moderately associated with decreased CBF, independent of reduced .
Lower Dimensional Model for Modeling the Heat Transfer and Detailed Reactions Inside Long Channels
Authors: Yadav Rakesh , Meeks Ellen , Goldin Graham , Orsino Stefano
Published: February 2016

A methodology has been developed for coupling the one-dimensional (1D) solution of flow inside the nonpermeable channels with the 3D outer flow in shell and tube type of configurations. In the proposed reacting channel, the 1D channels have detailed reactions while the outer 3D flow can be reactive or nonreactive. The channels are discretized into 1D grid points and a parabolic solver is used to solve the species transport and energy equations inside the channels. Since the walls of the channels are nonpermeable, the two zones are coupled only through the heat transfer. The current approach is tested and validated for a series of problems with increasing complexities. The predictions of the channel model (CM) are compared with 3D modeling of the channels and experimental data. The CM predictions are in excellent agreement with the fully resolved (FR) model with much less computational cost. The discussed methodology is useful for applications such as fuel reformers, hydrocarbon cracking furnaces, heat exchangers, etc.
An Experimental Study and Model Determination of the Mechanical Stiffness of Paper Folds
Authors: Pradier Clémentine , Cavoret Jérôme , Dureisseix David , Jean-Mistral Claire , Ville Fabrice
Published: February 2016

Over the past few decades, folding paper has extended beyond the origami deployable applications to reach the engineering field. Nevertheless, mechanical information about paper behavior is still lacking, especially during folding/unfolding. This article proposes an approach to characterize the paper fold behavior in order to extract the material data that will be needed for the simulation of folding and to go a step further the single kinematics of origami mechanisms. The model developed herein from simple experiments for the fold behavior relies on a macroscopic local hinge with a nonlinear torsional spring. Though validated with only straight folds, the model is still applicable in the case of curved folds thanks to the locality principle of the mechanical behavior. The influence of both the folding angle and the fold length is extracted automatically from a set of experimental values exhibiting a deterministic behavior and a variability due to the folding process. The goal is also to propose a methodology that may extend the simple case of the paper crease, or even the case of thin material sheets, and may be adapted to other identification problems.
Performance and Design Comparison of a Bulk Thermoelectric Cooler With a Hybrid Architecture
Authors: Antonik Margaret , O'Connor Brendan T. , Ferguson Scott
Published: February 2016

This paper compares the economic viability and performance outcomes of two different thermoelectric device architectures to determine the advantages and appropriate use of each configuration. Hybrid thermoelectric coolers (TECs) employ thin-film thermoelectric materials sandwiched between a plastic substrate and form a corrugated structure. Roll-to-roll (R2R) manufacturing and low-cost polymer materials offer a cost advantage to the hybrid architecture at the sacrifice of performance capabilities while conventional bulk devices offer increased performance at a higher cost. Performance characteristics and cost information are developed for both hybrid and conventional bulk single-stage thermoelectric modules. The design variables include device geometry, electrical current input, and thermoelectric material type. The tradeoffs between cooling performance and cost will be explored, and the thermoelectric system configuration is analyzed for both hybrid and conventional bulk TECs.
Effect of High-Temperature Corrosion on the Service Life of P91 Piping in Biomass Co-firing
Authors: O'Hagan C. P. , Barrett R. A. , Leen S. B. , Monaghan R. F. D.
Published: February 2016

Co-firing biomass with traditional fuels is becoming increasingly relevant to thermal power plant operators due to increasingly stringent regulations on greenhouse gas emissions. It has been found that when biomass is co-fired, an altered ash composition is formed, which leads to increased levels of corrosion of the superheater tube walls. Synthetic salt, which is representative of the ash formed in the co-firing of a 70% peat and 30% biomass mixture, has been produced and applied to samples of P91 at 540 °C for up to 28 days. This paper presents results for oxide layer thickness and loss of substrate from testing. Scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDX) element maps are obtained and presented in order to gain an understanding of the complex corrosion mechanism which occurs. A finite-element (FE) methodology is presented which combines corrosion effects with creep damage in pressurized tubes. The effects of corrosion tube wall loss and creep damage on tube stresses and creep life are investigated.
State Estimation Algorithm Based on a Disturbance Observer for a Free-Piston Engine Linear Generator
Authors: Goto Shigeaki , Moriya Kazunari , Kosaka Hidemasa , Akita Tomoyuki , Hotta Yoshihiro , Nakakita Kiyomi
Published: February 2016

In order to realize a thin, compact, efficient, and fuel-flexible power-generation system, we have been developing and investigating a free-piston engine linear generator (FPEG), which consists of a two-stroke combustion chamber and an adjustable gas spring chamber. This paper proposes a novel observer algorithm that has two advantages. First, the piston position can be interpolated at high accuracy beyond the resolution of the piston position sensor, which improves the accuracy and stability in controlling the combustion parameters, such as ignition timing and compression ratio. Second, the pressure in the gas spring chamber and the coefficient of damping (lubrication condition) are estimated simultaneously and independently. In this paper, the principle of the developed observer algorithm is described and tested through simulation and experimentation using the developed FPEG system. Based on the simulation, the output of the position sensor (resolution: 0.55 mm) was interpolated with an accuracy of ±0.1 mm. Based on the experimental results for the estimation of pressure in the gas spring chamber and the coefficient of damping, the feasibility of sensorless monitoring of the pressure in the gas spring chamber and the coefficient of damping has been verified.
Minority carrier lifetimes in very long-wave infrared InAs/GaInSb superlattices
Authors: Haugan Heather J. , Brown Gail J. , Olson Benjamin V. , Kadlec Emil A. , Kim Jin K. , Shaner Eric A.
Published: February 2016

Significantly improved carrier lifetimes in very-long wave infrared InAs/GaInSb superlattice (SL) absorbers are demonstrated by using time-resolved microwave reflectance (TMR) measurements. A nominal 47.0 Å InAs/21.5 Å Ga0.75In0.25Sb SL structure that produces an approximately 25 μm response at 10 K has a minority carrier lifetime of 140 ± 20 ns at 18 K, which is markedly long for SL absorber with such a narrow bandgap. This improvement is attributed to the strain-engineered ternary design. Such SL employs a shorter period with reduced gallium in order to achieve good optical absorption and epitaxial advantages, which ultimately leads to the improvements in the minority carrier lifetime by reducing Shockley–Read–Hall (SRH) defects. By analyzing the temperature-dependence of TMR decay data, the recombination mechanisms and trap states that currently limit the performance of this SL absorber have been identified. The results show a general decrease in the long-decay lifetime component, which is dominated by the SRH recombination at temperature below ∼30 K, and by Auger recombination at temperatures above ∼45 K.
An assessment of the direction-finding accuracy of bat biosonar beampatterns
Authors: Gilani Uzair S. , Müller Rolf
Published: February 2016

In the biosonar systems of bats, emitted acoustic energy and receiver sensitivity are distributed over direction and frequency through beampattern functions that have diverse and often complicated geometries. This complexity could be used by the animals to determine the direction of incoming sounds based on spectral signatures. The present study has investigated how well bat biosonar beampatterns are suited for direction finding using a measure of the smallest estimator variance that is possible for a given direction [Cramér-Rao lower bound (CRLB)]. CRLB values were estimated for numerical beampattern estimates derived from 330 individual shape samples, 157 noseleaves (used for emission), and 173 outer ears (pinnae). At an assumed 60 dB signal-to-noise ratio, the average value of the CRLB was 3.9°, which is similar to previous behavioral findings. Distribution for the CRLBs in individual beampatterns had a positive skew indicating the existence of regions where a given beampattern does not support a high accuracy. The highest supported accuracies were for direction finding in elevation (with the exception of phyllostomid emission patterns). No large, obvious differences in the CRLB (greater 2° in the mean) were found between the investigated major taxonomic groups, suggesting that different bat species have access to similar direction-finding information.
Modeling human echolocation of near-range targets with an audible sonar
Authors: Kuc Roman , Kuc Victor
Published: February 2016

Blind humans echolocate nearby targets by emitting palatal clicks and perceiving echoes that the auditory system is not able to resolve temporally. The mechanism for perceiving near-range echoes is not known. This paper models the direct mouth-to-ear signal (MES) and the echo to show that the echo enhances the high-frequency components in the composite MES/echo signal with features that allow echolocation. The mouth emission beam narrows with increasing frequency and exhibits frequency-dependent transmission notches in the backward direction toward the ears as predicted by the piston-in-sphere model. The ears positioned behind the mouth detect a MES that contains predominantly the low frequencies contained in the emission. Hence the high-frequency components in the emission that are perceived by the ears are enhanced by the echoes. A pulse/echo audible sonar verifies this model by echolocating targets from 5 cm range, where the MES and echo overlap significantly, to 55 cm. The model predicts that unambiguous ranging occurs over a limited range and that there is an optimal range that produces the highest range resolution.
Releasing aldolase from the cytoskeleton
Authors: Prabakaran Sudhakaran
Published: February 2016

Phosphoinositide 3-kinase (PI3K) had an AKT- and mTOR-independent role in promoting metabolism.
Combination of Amphotericin B and Flucytosine against Neurotropic Species of Melanized Fungi Causing Primary Cerebral Phaeohyphomycosis
Authors: Deng S. , Pan W. , Liao W. , de Hoog G. S. , Gerrits van den Ende A. H. G. , Vitale R. G. , Rafati H. , Ilkit M. , Van der Lee A. H. , Rijs A. J. M. M. , Verweij P. E. , Seyedmousavi S.
Published: February 2016

Primary central nervous system phaeohyphomycosis is a fatal fungal infection due mainly to the neurotropic melanized fungi
Cladophialophora bantiana
,
Rhinocladiella mackenziei
, and
Exophiala dermatitidis.
Despite the combination of surgery with antifungal treatment, the prognosis continues to be poor, with mortality rates ranging from 50 to 70%. Therefore, a search for a more-appropriate therapeutic approach is urgently needed. Our
in vitro
studies showed that with the combination of amphotericin B and flucytosine against these species, the median fractional inhibitory concentration (FIC) indices for strains ranged from 0.25 to 0.38, indicating synergy. By use of Bliss independence analysis, a significant degree of synergy was confirmed for all strains, with the sum ΔE ranging from 90.2 to 698.61%. No antagonism was observed. These results indicate that amphotericin B, in combination with flucytosine, may have a role in the treatment of primary cerebral infections caused by melanized fungi belonging to the order
Chaetothyriales
. Further
in vivo
studies and clinical investigations to elucidate and confirm these observations are warranted.
Amino Acid Substitutions Account for Most MexS Alterations in Clinical
nfxC
Mutants of Pseudomonas aeruginosa
Authors: Richardot Charlotte , Juarez Paulo , Jeannot Katy , Patry Isabelle , Plésiat Patrick , Llanes Catherine
Published: February 2016

Multidrug-resistant mutants of
Pseudomonas aeruginosa
that overproduce the active efflux system MexEF-OprN (called
nfxC
mutants) have rarely been characterized in the hospital setting. Screening of 221 clinical strains exhibiting a reduced susceptibility to ciprofloxacin (a substrate of MexEF-OprN) and imipenem (a substrate of the negatively coregulated porin OprD) led to the identification of 43 (19.5%)
nfxC
mutants. Subsequent analysis of 22 nonredundant mutants showed that, in contrast to their
in vitro
-selected counterparts, only 3 of them (13.6%) harbored a disrupted
mexS
gene, which codes for the oxidoreductase MexS, whose inactivation is known to activate the
mexEF-oprN
operon through a LysR-type regulator, MexT. Nine (40.9%) of the clinical
nfxC
mutants contained single amino acid mutations in MexS, and these were associated with moderate effects on resistance and virulence factor production in 8/9 strains. Finally, the remaining 10 (45.5%)
nfxC
mutants did not display mutations in any of the regulators known to control
mexEF-oprN
expression (the
mexS
,
mexT
,
mvaT
, and
ampR
genes), confirming that other loci are responsible for pump upregulation in patients. Collectively, these data demonstrate that
nfxC
mutants are probably more frequent in the hospital than previously thought and have genetic and phenotypic features somewhat different from those of
in vitro
-selected mutants.
Cell Wall Changes in Amphotericin B-Resistant Strains from Candida tropicalis and Relationship with the Immune Responses Elicited by the Host
Authors: Mesa-Arango Ana C. , Rueda Cristina , Román Elvira , Quintin Jessica , Terrón María C. , Luque Daniel , Netea Mihai G. , Pla Jesus , Zaragoza Oscar
Published: February 2016

We have morphologically characterized
Candida tropicalis
isolates resistant to amphotericin B (AmB). These isolates present an enlarged cell wall compared to isolates of regular susceptibility. This correlated with higher levels of β-1,3-glucan in the cell wall but not with detectable changes in chitin content. In line with this, AmB-resistant strains showed reduced susceptibility to Congo red. Moreover, mitogen-activated protein kinases (MAPKs) involved in cell integrity were already activated during regular growth in these strains. Finally, we investigated the response elicited by human blood cells and found that AmB-resistant strains induced a stronger proinflammatory response than susceptible strains. In agreement, AmB-resistant strains also induced stronger melanization of
Galleria mellonella
larvae, indicating that the effect of alterations of the cell wall on the immune response is conserved in different types of hosts. Our results suggest that resistance to AmB is associated with pleiotropic mechanisms that might have important consequences, not only for the efficacy of the treatment but also for the immune response elicited by the host.
5-Azacytidine Enhances the Mutagenesis of HIV-1 by Reduction to 5-Aza-2′-Deoxycytidine
Authors: Rawson Jonathan M. O. , Daly Michele B. , Xie Jiashu , Clouser Christine L. , Landman Sean R. , Reilly Cavan S. , Bonnac Laurent , Kim Baek , Patterson Steven E. , Mansky Louis M.
Published: February 2016

5-Azacytidine (5-aza-C) is a ribonucleoside analog that induces the lethal mutagenesis of human immunodeficiency virus type 1 (HIV-1) by causing predominantly G-to-C transversions during reverse transcription. 5-Aza-C could potentially act primarily as a ribonucleotide (5-aza-CTP) or as a deoxyribonucleotide (5-aza-2′-deoxycytidine triphosphate [5-aza-dCTP]) during reverse transcription. In order to determine the primary form of 5-aza-C that is active against HIV-1, Illumina sequencing was performed using proviral DNA from cells treated with 5-aza-C or 5-aza-dC. 5-Aza-C and 5-aza-dC were found to induce highly similar patterns of mutation in HIV-1 in terms of the types of mutations observed, the magnitudes of effects, and the distributions of mutations at individual sequence positions. Further, 5-aza-dCTP was detected by liquid chromatography–tandem mass spectrometry in cells treated with 5-aza-C, demonstrating that 5-aza-C was a substrate for ribonucleotide reductase. Notably, levels of 5-aza-dCTP were similar in cells treated with equivalent effective concentrations of 5-aza-C or 5-aza-dC. Lastly, HIV-1 reverse transcriptase was found to incorporate 5-aza-CTP
in vitro
at least 10,000-fold less efficiently than 5-aza-dCTP. Taken together, these data support the model that 5-aza-C enhances the mutagenesis of HIV-1 primarily after reduction to 5-aza-dC, which can then be incorporated during reverse transcription and lead to G-to-C hypermutation. These findings may have important implications for the design of new ribonucleoside analogs directed against retroviruses.
Characterization of SlyA in Shigella flexneri Identifies a Novel Role in Virulence
Authors: Weatherspoon-Griffin Natasha , Wing Helen J.
Published: February 2016

The SlyA transcriptional regulator has important roles in the virulence and pathogenesis of several members of the
Enterobacteriaceae
family, including
Salmonella enterica
serovar Typhimurium and
Escherichia coli
. Despite the identification of the
slyA
gene in
Shigella flexneri
nearly 2 decades ago, as well as the significant conservation of SlyA among enteric bacteria, the role of SlyA in
Shigella
remains unknown. The genes regulated by SlyA in closely related organisms often are absent from or mutated in
S. flexneri
, and consequently many described SlyA-dependent phenotypes are not present. By characterizing the expression of
slyA
and determining its ultimate effect in this highly virulent organism, we postulated that novel SlyA-regulated virulence phenotypes would be identified. In this study, we report the first analysis of SlyA in
Shigella
and show that (i) the
slyA
gene is transcribed and ultimately translated into protein, (ii)
slyA
promoter activity is maximal during stationary phase and is negatively autoregulated and positively regulated by the PhoP response regulator, (iii) the exogenous expression of
slyA
rescues transcription and virulence-associated deficiencies during virulence-repressed conditions, and (iv) the absence of
slyA
significantly decreases acid resistance, demonstrating a novel and important role in
Shigella
virulence. Cumulatively, our study illustrates unexpected parallels between the less conserved
S. flexneri
and
S
. Typhimurium
slyA
promoters as well as a unique role for SlyA in
Shigella
virulence that has not been described previously in any closely related organism.
Flagellar Cap Protein FliD Mediates Adherence of Atypical Enteropathogenic Escherichia coli to Enterocyte Microvilli
Authors: Sampaio Suely C. F. , Luiz Wilson B. , Vieira Mônica A. M. , Ferreira Rita C. C. , Garcia Bruna G. , Sinigaglia-Coimbra Rita , Sampaio Jorge L. M. , Ferreira Luís C. S. , Gomes Tânia A. T.
Published: February 2016

The expression of flagella correlates with different aspects of bacterial pathogenicity, ranging from adherence to host cells to activation of inflammatory responses by the innate immune system. In the present study, we investigated the role of flagella in the adherence of an atypical enteropathogenic
Escherichia coli
(aEPEC) strain (serotype O51:H40) to human enterocytes. Accordingly, isogenic mutants deficient in flagellin (FliC), the flagellar structural subunit; the flagellar cap protein (FliD); or the MotAB proteins, involved in the control of flagellar motion, were generated and tested for binding to differentiated Caco-2 cells. Binding of the aEPEC strain to enterocytes was significantly impaired in strains with the
fliC
and
fliD
genes deleted, both of which could not form flagella on the bacterial surface. A nonmotile but flagellated MotAB mutant also showed impaired adhesion to Caco-2 cells. In accordance with these observations, adhesion of aEPEC strain 1711-4 to Caco-2 cells was drastically reduced after the treatment of Caco-2 cells with purified FliD. In addition, incubation of aEPEC bacteria with specific anti-FliD serum impaired binding to Caco-2 cells. Finally, incubation of Caco-2 cells with purified FliD, followed by immunolabeling, showed that the protein was specifically bound to the microvillus tips of differentiated Caco-2 cells. The aEPEC FliD or anti-FliD serum also reduced the adherence of prototype typical enteropathogenic, enterohemorrhagic, and enterotoxigenic
E. coli
strains to Caco-2 cells. In conclusion, our findings further strengthened the role of flagella in the adherence of aEPEC to human enterocytes and disclosed the relevant structural and functional involvement of FliD in the adhesion process.
Pathophysiological Mechanisms in Gaseous Therapies for Severe Malaria
Authors: Kayano Ana Carolina A. V. , Dos-Santos João Conrado K. , Bastos Marcele F. , Carvalho Leonardo J. , Aliberti Júlio , Costa Fabio T. M.
Published: February 2016

Over 200 million people worldwide suffer from malaria every year, a disease that causes 584,000 deaths annually. In recent years, significant improvements have been achieved on the treatment of severe malaria, with intravenous artesunate proving superior to quinine. However, mortality remains high, at 8% in children and 15% in adults in clinical trials, and even worse in the case of cerebral malaria (18% and 30%, respectively). Moreover, some individuals who do not succumb to severe malaria present long-term cognitive deficits. These observations indicate that strategies focused only on parasite killing fail to prevent neurological complications and deaths associated with severe malaria, possibly because clinical complications are associated in part with a cerebrovascular dysfunction. Consequently, different adjunctive therapies aimed at modulating malaria pathophysiological processes are currently being tested. However, none of these therapies has shown unequivocal evidence in improving patient clinical status. Recently, key studies have shown that gaseous therapies based mainly on nitric oxide (NO), carbon monoxide (CO), and hyperbaric (pressurized) oxygen (HBO) alter vascular endothelium dysfunction and modulate the host immune response to infection. Considering gaseous administration as a promising adjunctive treatment against severe malaria cases, we review here the pathophysiological mechanisms and the immunological aspects of such therapies.
Listeria monocytogenes σHContributes to Expression of Competence Genes and Intracellular Growth
Authors: Medrano Romero Veronica , Morikawa Kazuya
Published: February 2016

The alternative sigma factor σHhas two functions in Gram-positive bacteria: it regulates sporulation and the development of genetic competence.Listeria monocytogenesis a nonsporulating species in which competence has not yet been detected. Nevertheless, the main competence regulators and a series of orthologous genes that form the competence machinery are present in its genome; some of the competence genes play a role in optimal phagosomal escape. In this study, strains overexpressing σHand strains with a σHdeletion were used to elucidate the contribution of σHto the expression of the competence machinery genes inL. monocytogenes. Gene expression analysis showed that σHis, indeed, involved incomGandcomEregulation. Unexpectedly, we observed a unique regulation scheme in which σHand the transcription factor ComK were involved. Population-level analysis showed that even with the overexpression of both factors, only a fraction of the cells expressed the competence machinery genes. Although we could not detect competence, σHwas crucial for phagosomal escape, which implies that this alternative sigma factor has specifically evolved to regulate theL. monocytogenesintracellular life cycle.

IMPORTANCEListeria monocytogenescan be an intracellular pathogen capable of causing serious infections in humans and animal species. Recently, the competence machinery genes were described as being necessary for optimal phagosomal escape, in which the transcription factor ComK plays an important role. On the other hand, our previous phylogenetic analysis suggested that the alternative sigma factor σHmight play a role in the regulation of competence genes. The present study shows that some of the competence genes belong to the σHregulon and, importantly, that σHis essential for intracellular growth, implying a unique physiological role of σHamongFirmicutes.
Rapid Evolution of Citrate Utilization by Escherichia coli by Direct Selection Requires
citT
and
dctA
Authors: Van Hofwegen Dustin J. , Hovde Carolyn J. , Minnich Scott A.
Published: February 2016

The isolation of aerobic citrate-utilizing
Escherichia coli
(Cit
+
) in long-term evolution experiments (LTEE) has been termed a rare, innovative, presumptive speciation event. We hypothesized that direct selection would rapidly yield the same class of
E. coli
Cit
+
mutants and follow the same genetic trajectory: potentiation, actualization, and refinement. This hypothesis was tested with wild-type
E. coli
strain B and with K-12 and three K-12 derivatives: an
E. coli
Δ
rpoS
::
kan
mutant (impaired for stationary-phase survival), an
E. coli
Δ
citT
::
kan
mutant (deleted for the anaerobic citrate/succinate antiporter), and an
E. coli
Δ
dctA
::
kan
mutant (deleted for the aerobic succinate transporter).
E. coli
underwent adaptation to aerobic citrate metabolism that was readily and repeatedly achieved using minimal medium supplemented with citrate (M9C), M9C with 0.005% glycerol, or M9C with 0.0025% glucose. Forty-six independent
E. coli
Cit
+
mutants were isolated from all
E. coli
derivatives except the
E. coli
Δ
citT
::
kan
mutant. Potentiation/actualization mutations occurred within as few as 12 generations, and refinement mutations occurred within 100 generations. Citrate utilization was confirmed using Simmons, Christensen, and LeMaster Richards citrate media and quantified by mass spectrometry.
E. coli
Cit
+
mutants grew in clumps and in long incompletely divided chains, a phenotype that was reversible in rich media. Genomic DNA sequencing of four
E. coli
Cit
+
mutants revealed the required sequence of mutational events leading to a refined Cit
+
mutant. These events showed amplified
citT
and
dctA
loci followed by DNA rearrangements consistent with promoter capture events for
citT
. These mutations were equivalent to the amplification and promoter capture CitT-activating mutations identified in the LTEE.

IMPORTANCE
E. coli
cannot use citrate aerobically. Long-term evolution experiments (LTEE) performed by Blount et al. (Z. D. Blount, J. E. Barrick, C. J. Davidson, and R. E. Lenski, Nature 489:513–518, 2012,
http://dx.doi.org/10.1038/nature11514
) found a single aerobic, citrate-utilizing
E. coli
strain after 33,000 generations (15 years). This was interpreted as a speciation event. Here we show why it probably was not a speciation event. Using similar media, 46 independent citrate-utilizing mutants were isolated in as few as 12 to 100 generations. Genomic DNA sequencing revealed an amplification of the
citT
and
dctA
loci and DNA rearrangements to capture a promoter to express CitT, aerobically. These are members of the same class of mutations identified by the LTEE. We conclude that the rarity of the LTEE mutant was an artifact of the experimental conditions and not a unique evolutionary event. No new genetic information (novel gene function) evolved.
The SOS Response Master Regulator LexA Regulates the Gene Transfer Agent of Rhodobacter capsulatus and Represses Transcription of the Signal Transduction Protein CckA
Authors: Kuchinski Kevin S. , Brimacombe Cedric A. , Westbye Alexander B. , Ding Hao , Beatty J. Thomas
Published: February 2016

The gene transfer agent of
Rhodobacter capsulatus
(RcGTA) is a genetic exchange element that combines central aspects of bacteriophage-mediated transduction and natural transformation. RcGTA particles resemble a small double-stranded DNA bacteriophage, package random ∼4-kb fragments of the producing cell genome, and are released from a subpopulation (<1%) of cells in a stationary-phase culture. RcGTA particles deliver this DNA to surrounding
R. capsulatus
cells, and the DNA is integrated into the recipient genome though a process that requires homologs of natural transformation genes and RecA-mediated homologous recombination. Here, we report the identification of the LexA repressor, the master regulator of the SOS response in many bacteria, as a regulator of RcGTA activity. Deletion of the
lexA
gene resulted in the abolition of detectable RcGTA production and an ∼10-fold reduction in recipient capability. A search for SOS box sequences in the
R. capsulatus
genome sequence identified a number of putative binding sites located 5′ of typical SOS response coding sequences and also 5′ of the RcGTA regulatory gene
cckA
, which encodes a hybrid histidine kinase homolog. Expression of
cckA
was increased >5-fold in the
lexA
mutant, and a
lexA cckA
double mutant was found to have the same phenotype as a Δ
cckA
single mutant in terms of RcGTA production. The data indicate that LexA is required for RcGTA production and maximal recipient capability and that the RcGTA-deficient phenotype of the
lexA
mutant is largely due to the overexpression of
cckA
.

IMPORTANCE
This work describes an unusual phenotype of a
lexA
mutant of the alphaproteobacterium
Rhodobacter capsulatus
in respect to the phage transduction-like genetic exchange carried out by the
R. capsulatus
gene transfer agent (RcGTA). Instead of the expected SOS response characteristic of prophage induction, this
lexA
mutation not only abolishes the production of RcGTA particles but also impairs the ability of cells to receive RcGTA-borne genes. The data show that, despite an apparent evolutionary relationship to lambdoid phages, the regulation of RcGTA gene expression differs radically.
Arm-in-Arm Response Regulator Dimers Promote Intermolecular Signal Transduction
Authors: Baker Anna W. , Satyshur Kenneth A. , Moreno Morales Neydis , Forest Katrina T.
Published: February 2016

Bacteriophytochrome photoreceptors (BphPs) and their cognate response regulators make up two-component signal transduction systems which direct bacteria to mount phenotypic responses to changes in environmental light quality. Most of these systems utilize single-domain response regulators to transduce signals through unknown pathways and mechanisms. Here we describe the photocycle and autophosphorylation kinetics of RtBphP1, a red light-regulated histidine kinase from the desert bacterium
Ramlibacter tataouinensis
. RtBphP1 undergoes red to far-red photoconversion with rapid thermal reversion to the dark state. RtBphP1 is autophosphorylated in the dark; this activity is inhibited under red light. The RtBphP1 cognate response regulator, the
R. tataouinensis
bacteriophytochrome response regulator (RtBRR), and a homolog, AtBRR from
Agrobacterium tumefaciens
, crystallize unexpectedly as arm-in-arm dimers, reliant on a conserved hydrophobic motif, hFWAhL (where h is a hydrophobic M, V, L, or I residue). RtBRR and AtBRR dimerize distinctly from four structurally characterized phytochrome response regulators found in photosynthetic organisms and from all other receiver domain homodimers in the Protein Data Bank. A unique cacodylate-zinc-histidine tag metal organic framework yielded single-wavelength anomalous diffraction phases and may be of general interest. Examination of the effect of the BRR stoichiometry on signal transduction showed that phosphorylated RtBRR is accumulated more efficiently than the engineered monomeric RtBRR (RtBRR
mon
) in phosphotransfer reactions. Thus, we conclude that arm-in-arm dimers are a relevant signaling intermediate in this class of two-component regulatory systems.

IMPORTANCE
BphP histidine kinases and their cognate response regulators comprise widespread red light-sensing two-component systems. Much work on BphPs has focused on structural understanding of light sensing and on enhancing the natural infrared fluorescence of these proteins, rather than on signal transduction or the resultant phenotypes. To begin to address this knowledge gap, we solved the crystal structures of two single-domain response regulators encoded by a region immediately downstream of that encoding BphPs. We observed a previously unknown arm-in-arm dimer linkage. Monomerization via deletion of the C-terminal dimerization motif had an inhibitory effect on net response regulator phosphorylation, underlining the importance of these unusual dimers for signal transduction.