bluuebunny/crossref_metadata_2025 huggingface dataset:
The Arabidopsis lectin receptor kinase LecRK‐I.9 enhances resistance to Phytophthora infestans in Solanaceous plants
Authors: Bouwmeester Klaas , Han Miao , Blanco‐Portales Rosario , Song Wei , Weide Rob , Guo Li‐Yun , van der Vossen Edwin A.G. , Govers Francine
Published: August 2013

Late blight caused by the plant pathogenic oomycete Phytophthora infestans is known as one of the most destructive potato diseases. Plant breeders tend to employ NB‐LRR‐based resistance for introducing genetically controlled late blight resistance in their breeding lines. However, P. infestans is able to rapidly escape this type of resistance, and hence, NB‐LRR‐based resistance in potato cultivars is often not durable. Previously, we identified a novel type of Phytophthora resistance in Arabidopsis. This resistance is mediated by the cell surface receptor LecRK‐I.9, which belongs to the family of L‐type lectin receptor kinases. In this study, we report that expression of the Arabidopsis LecRK‐I.9 gene in potato and Nicotiana benthamiana results in significantly enhanced late blight resistance. Transcriptional profiling showed strong reduction in salicylic acid (SA)‐mediated defence gene expression in LecRK‐I.9 transgenic potato lines (TPLs). In contrast, transcripts of two protease inhibitor genes accumulated to extreme high levels, suggesting that LecRK‐I.9‐mediated late blight resistance is relying on a defence response that includes activation of protease inhibitors. These results demonstrate that the functionality of LecRK‐I.9 in Phytophthora resistance is maintained after interfamily transfer to potato and N. benthamiana and suggest that this novel type of LecRK‐based resistance can be exploited in breeding strategies to improve durable late blight resistance in Solanaceous crops.
The epithelium specific cell cycle regulator 14‐3‐3sigma is required for preventing entry into mitosis following ultraviolet B
Authors: Vogel Sandra , Herzinger Thomas
Published: August 2013

Background

Deoxyribonucleic acid damage activates cell cycle checkpoints in order to maintain genomic stability. We assessed the role of different checkpoint genes in response to ultraviolet B irradiation.

Methods

Cell lines expressing a dominant negative mutant of ataxia telangiectasia and Rad3 related (Atr) protein or overexpressing Cdc25A, cells deficient for 14‐3‐3σ, Nijmegen breakage syndrome (Nbs), or Ataxia telangiectasia mutated (Atm) were treated with ultraviolet B (UVB) and harvested after 12 h, 24 h, or 48 h for analysis by flow cytometry.

Results

Functional loss of Atm, Atr, or Nbs did not result in a significant alteration of the cell cycle profile. Overexpression of Cdc25A led to a delayed arrest at the G1/S transition in response to low doses of UVB. Loss of 14‐3‐3σ, a negative cell cycle regulator and downstream target of p53, caused a transient arrest at the G2/M boundary.

Conclusions

Loss of 14‐3‐3σ sensitizes cells to UVB. After a transient cell cycle arrest, 14‐3‐3σ‐deficient cells die by undergoing mitotic catastrophe. Cdc25A overexpression causes a delayed arrest in response to low doses of UVB. After higher doses, Cdc25A is no longer able to overrun the checkpoint. Atm, Atr, or Nbs are not essential for the checkpoint response to UVB, suggesting the existence of redundant signaling pathways.
The behavioral impact of baroreflex function: A review
Authors: Duschek Stefan , Werner Natalie S. , Reyes del Paso Gustavo A.
Published: August 2013

The baroreflex consists of a negative feedback loop adjusting heart activity to blood pressure fluctuations. This review is concerned with interactions between baroreflex function and behavior. In addition to changes in baroreflex cardiac control subject to behavioral manipulations, interindividual differences in reflex function predicted psychological and central nervous features. The sensitivity of the reflex was inversely related to cognitive performance, evoked potential amplitudes, experimental pain sensitivity, and the severity of clinical pain. Possible variables moderating the strength of the associations are tonic blood pressure, gender, and psychiatric disease. It is suggested that these observations reflect inhibition of higher brain function by baroreceptor afferents. While in many cases increased baroreflex function implies stronger inhibition, individual and situational factors modulate the behavioral impact of cardiac regulation.
Redefining the damselfly families: a comprehensive molecular phylogeny of Zygoptera (Odonata)
Authors: DIJKSTRA KLAAS‐DOUWE B. , KALKMAN VINCENT J. , DOW RORY A. , STOKVIS FRANK R. , VAN TOL JAN
Published: August 2013

An extensive molecular phylogenetic reconstruction of the suborder Zygoptera of the Odonata is presented, based on mitochondrial (16S, COI) and nuclear (28S) data of 59% of the 310 genera recognized and all (suspected) families except the monotypic Hemiphlebiidae. A partial reclassification is proposed, incorporating morphological characters. Many traditional families are recovered as monophyletic, but reorganization of the superfamily Coenagrionoidea into three families is proposed: Isostictidae, Platycnemididae and Coenagrionidae. Archboldargia Lieftinck, Hylaeargia Lieftinck, Palaiargia Förster, Papuargia Lieftinck and Onychargia Selys are transferred from Coenagrionidae to Platycnemididae, and Leptocnemis Selys, Oreocnemis Pinhey and Thaumatagrion Lieftinck from Platycnemididae to Coenagrionidae. Each geographically well‐defined clade of Platycnemididae is recognized as a subfamily, and thus Disparoneurinae (i.e. Old World ‘Protoneuridae’) is incorporated, Calicnemiinae is restricted, and Allocnemidinae (type genus: Allocnemis Selys) subfam.n., Idiocnemidinae (type genus: Idiocnemis Selys) subfam.n. and Onychargiinae (type genus: Onychargia Selys) subfam.n. and Coperini trib.n. (type genus: Copera Kirby) are described. Half of Coenagrionidae belongs to a well‐supported clade incorporating Coenagrion Kirby and the potential subfamilies Agriocnemidinae, Ischnurinae and Pseudagrioninae. The remainder is less well defined, but includes the Pseudostigmatidae and New World Protoneuridae that, with Argiinae and Teinobasinae, may prove valid subfamilies with further evidence. Ninety‐two per cent of the genera formerly included in the polyphyletic Amphipterygidae and Megapodagrionidae were studied. Pentaphlebiidae, Rimanellidae and Devadattidae fam.n. (type genus: Devadatta Kirby) are separated from Amphipterygidae, and Argiolestidae, Heteragrionidae, Hypolestidae, Philogeniidae, Philosinidae and Thaumatoneuridae from Megapodagrionidae. Eight further groups formerly placed in the latter are identified, but are retained as incertae sedis; the validity of Lestoideidae, Philogangidae and Pseudolestidae is confirmed. For some families (e.g. Calopterygidae, Chlorocyphidae) a further subdivision is possible; Protostictinae subfam.n. (type genus: Protosticta Selys) is introduced in Platystictidae. Numerous new combinations are proposed in the Supporting Information. Many long‐established families lack strong morphological apomorphies. In particular, venation is incongruent with molecular results, stressing the need to review fossil Odonata taxonomy: once defined by the reduction of the anal vein, Protoneuridae dissolves completely into six clades from five families.
Cryptococcal meningitis presenting as sinusitis in a renal transplant recipient
Authors: Iyer S.P. , Movva K. , Wiebel M. , Chandrasekar P. , Alangaden G. , Carron M. , Tranchida P. , Revankar S.G.
Published: August 2013

Cryptococcal meningitis is a relatively common invasive fungal infection in immunocompromised patients, especially in solid organ transplant recipients. Clinical presentation typically includes fever, headache, photophobia, neck stiffness, and/or altered mental status. Unusual presentations may delay diagnosis. Therapy is challenging in renal transplant patients because of the nephrotoxicity associated with amphotericin B, the recommended treatment. We present a case of cryptococcal meningitis in a renal transplant recipient presenting as acute sinusitis with successful treatment using fluconazole as primary therapy.
International survey on plasma transfusion practices in critically ill children
Authors: Karam Oliver , Tucci Marisa , Lacroix Jacques , Rimensberger Peter C. ,   Canadian Critical Care Trials Group and of the Pediatric Acute Lung Injury and Sepsis Investigator Network
Published: August 2013

Background

Studies have shown heterogeneity in red blood cell transfusion practices. Although plasma transfusion is common in intensive care, there are no data on plasma transfusion practices in pediatric critical care units.

Study Design and Methods

A scenario‐based survey was sent to 718 pediatric critical care physicians working in Europe, North America, Australia, and New Zealand. Respondents were asked to report their decisions regarding plasma transfusion practice with respect to four scenarios: pneumonia, septic shock, traumatic brain injury (TBI), and postoperative care after a Tetralogy of Fallot correction.

Results

The response rate was 187 of 718 (26%); half of the responders worked in North America. The proportion of physicians who transfused plasma to nonbleeding patients, solely based on abnormal international normalized ratio (INR), varied from 66% for pneumonia to 84% for TBI (p < 0.001). In such nonbleeding patients, the median INR threshold that would trigger plasma transfusion was 2.5 for pneumonia and septic shock patients and 2.0 for TBI and the cardiac postoperative patients (p < 0.001). Minor bleeding, minor surgery, insertion of a femoral line, hypotension, abnormal activated partial thromboplastin time, thrombocytopenia, and anemia levels were important determinants of plasma transfusion, whereas none of the respondents' demographic characteristics were important.

Conclusion

More than two‐thirds of responding pediatric critical care physicians prescribe plasma transfusions for nonbleeding critically ill children. Additionally, there is a significant variation in transfusion practice patterns with respect to plasma transfusion thresholds.
Predicting blood donation maintenance: the importance of planning future donations
Authors: van Dongen Anne , Ruiter Robert , Abraham Charles , Veldhuizen Ingrid
Published: August 2013

Background

Interventions to retain blood donors need to target the most influential and changeable factors. This study tested antecedents of three successive donation decisions.

Study Design and Methods

Participants were donors who had donated for the first time 1 year previous (n = 1018). Intention to continue donating, vasovagal reactions, deferral, anxiety, and planning failure were measured. Analyses distinguished between 1) those who registered for donation after questionnaire completion, versus those who did not; 2) those who did or did not register for donation a second time after questionnaire completion; and 3) those who did or did not register for donation a third time after questionnaire completion.

Results

Three logistic regression analyses showed that the first donation decision was influenced by intention (odds ratio [OR], 1.70; 95% confidence interval [CI], 1.30‐2.21), number of donations made in the first year (OR, 2.35; 95% CI, 1.81‐3.06), vasovagal reactions (OR, 0.92; 95% CI, 0.87‐0.97), and planning failure (OR, 0.81; 95% CI, 0.70‐0.95). The second donation decision was influenced by intention (OR, 1.44; 95% CI, 1.06‐1.95) and planning failure (OR, 0.67; 95% CI, 0.57‐0.78), while the third decision was influenced only by planning failure (OR, 0.85; 95% CI, 0.73‐1.00).

Conclusion

This indicates that for new donors, retention efforts should focus on the promotion of a positive intention and decreasing vasovagal reactions. However, decreasing planning failure could be an even better investment since planning seems to determine long‐term retention.
Enhanced Groove Geometry for Herringbone Grooved Journal Bearings
Authors: Schiffmann J.
Published: August 2013

Although gas-lubricated herringbone grooved journal bearings (HGJB) are known for high rotordynamic stability thresholds, small clearance to diameter ratios are required for stable rotor operation. Tight clearances not only increase bearing losses but also yield challenging manufacturing and assembly tolerances, which ultimately translate into cost. Traditionally, the grooves of HGJB are of helical nature with constant cross section and pitch. The current paper aims at increasing the clearance to diameter ratio and the stability threshold of grooved bearings by introducing enhanced groove geometries. The axial evolution of groove width, depth, and local pitch are described by individual third order polynomials with four interpolation points. The expression for the smooth pressure distribution resulting from the narrow groove theory is modified to enable the calculation of bearing properties with modified groove patterns. The reduced order bearing model is coupled to a linear rigid body rotordynamic model for predicting the whirl speed map and the corresponding stability. By introducing a critical mass parameter as a measure for stability, a criterion for the instability onset is proposed. The optimum groove geometry is found by coupling the gas bearing supported rotor model with a multiobjective optimizer. By maximizing both the clearance to diameter ratio and the rotordynamic stability it is shown that with optimal groove geometry, which deviates from helicoids with constant pitch and cross section, the critical mass parameter can be improved by more than one order of magnitude compared to traditional HGJB geometries. The clearance to diameter ratio can be increased by up to 80% while keeping the same stability margin, thus reducing both losses and manufacturing constraints. The optimum groove pattern distributions (width ratio, angle, and depth) are summarized for a variety of L/D ratios and for different compressibility numbers in a first attempt to set up general design guidelines for enhanced gas-lubricated HGJB.
Thermoacoustic Shape Optimization of a Subsonic Nozzle
Authors: Giauque Alexis , Huet Maxime , Clero Franck , Ducruix Sébastien , Richecoeur Franck
Published: August 2013

Indirect combustion noise originates from the acceleration of nonuniform temperature or high vorticity regions when convected through a nozzle or a turbine. In a recent contribution (Giauque et al., 2012, “Analytical Analysis of Indirect Combustion Noise in Subcritical Nozzles,” ASME J. Eng. Gas Turbies Power, 134(11), p. 111202) the authors have presented an analytical thermoacoustic model providing the indirect combustion noise generated by a subcritical nozzle when forced with entropy waves. This model explicitly takes into account the effect of the local changes in the cross-section area along the configuration of interest. In this article, the authors introduce this model into an optimization procedure in order to minimize or maximize the thermoacoustic noise emitted by arbitrarily shaped nozzles operating under subsonic conditions. Each component of the complete algorithm is described in detail. The evolution of the cross-section changes are introduced using Bezier's splines, which provide the necessary freedom to actually achieve arbitrary shapes. Bezier's polar coordinates constitute the parameters defining the geometry of a given individual nozzle. Starting from a population of nozzles of random shapes, it is shown that a specifically designed genetic optimization algorithm coupled with the analytical model converges at will toward a quieter or noisier population. As already described by Bloy (Bloy, 1979, “The Pressure Waves Produced by the Convection of Temperature Disturbances in High Subsonic Nozzle Flows,” J. Fluid Mech., 94(3), pp. 465–475), the results therefore confirm the significant dependence of the indirect combustion noise with respect to the shape of the nozzle, even when the operating regime is kept constant. It appears that the quietest nozzle profile evolves almost linearly along its converging and diverging sections, leading to a square evolution of the cross-section area. Providing insight into the underlying physical reason leading to the difference in the noise emission between two extreme individuals, the integral value of the source term of the equation describing the behavior of the acoustic pressure of the nozzle is considered. It is shown that its evolution with the frequency can be related to the global acoustic emission. Strong evidence suggest that the noise emission increases as the source term in the converging and diverging parts less compensate each other. The main result of this article is the definition and proposition of an acoustic emission factor, which can be used as a surrogate to the complex determination of the exact acoustic levels in the nozzle for the thermoacoustic shape optimization of nozzle flows. This acoustic emission factor, which is much faster to compute, only involves the knowledge of the evolution of the cross-section area and the inlet thermodynamic and velocity characteristics to be computed.
SIMS of organics—Advances in 2D and 3D imaging and future outlook
Authors: Gilmore Ian S.
Published: August 2013

Secondary ion mass spectrometry(SIMS) has become a powerful technique for the label-free analysis of organics from cells to electronic devices. The development of cluster ion sources has revolutionized the field, increasing the sensitivity for organics by two or three orders of magnitude and for large clusters, such as C60 and argon clusters, allowing depth profiling of organics. The latter has provided the capability to generate stunning three dimensional images with depth resolutions of around 5 nm, simply unavailable by other techniques. Current state-of-the-art allows molecular images with a spatial resolution of around 500 nm to be achieved and future developments are likely to progress into the sub-100 nm regime. This review is intended to bring those with some familiarity with SIMS up-to-date with the latest developments for organics, the fundamental principles that underpin this and define the future progress. State-of-the-art examples are showcased and signposts to more in-depth reviews about specific topics given for the specialist.
Surface characterization of nanomaterials and nanoparticles: Important needs and challenging opportunities
Authors: Baer Donald R. , Engelhard Mark H. , Johnson Grant E. , Laskin Julia , Lai Jinfeng , Mueller Karl , Munusamy Prabhakaran , Thevuthasan Suntharampillai , Wang Hongfei , Washton Nancy , Elder Alison , Baisch Brittany L. , Karakoti Ajay , Kuchibhatla Satyanarayana V. N. T. , Moon DaeWon
Published: August 2013

This review examines characterization challenges inherently associated with understanding nanomaterials and the roles surface and interface characterization methods can play in meeting some of the challenges. In parts of the research community, there is growing recognition that studies and published reports on the properties and behaviors of nanomaterials often have reported inadequate or incomplete characterization. As a consequence, the true value of the data in these reports is, at best, uncertain. With the increasing importance of nanomaterials in fundamental research and technological applications,it is desirable that researchers from the wide variety of disciplines involved recognize the nature of these often unexpected challenges associated with reproducible synthesis and characterization of nanomaterials, including the difficulties of maintaining desired materials properties during handling and processing due to their dynamic nature. It is equally valuable for researchers to understand how characterization approaches (surface and otherwise) can help to minimize synthesis surprises and to determine how (and how quickly) materials and properties change in different environments. Appropriate application of traditional surface sensitive analysis methods (including x-ray photoelectron and Auger electron spectroscopies, scanning probe microscopy, and secondary ion mass spectroscopy) can provide information that helps address several of the analysis needs. In many circumstances, extensions of traditional data analysis can provide considerably more information than normally obtained from the data collected. Less common or evolving methods with surface selectivity (e.g., some variations of nuclear magnetic resonance, sum frequency generation, and low and medium energy ion scattering) can provide information about surfaces or interfaces in working environments (operando or in situ) or information not provided by more traditional methods. Although these methods may require instrumentation or expertise not generally available, they can be particularly useful in addressing specific questions, and examples of their use in nanomaterial research are presented.
Band offsets, Schottky barrier heights, and their effects on electronic devices
Authors: Robertson John
Published: August 2013

The authors review the band line-ups and band offsets between semiconductors, dielectrics, and metals,including the theory, experimental data, and the chemical trends. Band offsets have been critical in the choice of high dielectric constant oxides to be used in advanced metal oxide semiconductor field effect transistors. It turns out that band offsets are also critical in the theory of doping limits, design of transparent conducting oxides, organic semiconductors, and electrodes to use in light emitting devices, photovoltaic cells, and photochemical cells. It is shown how band line-ups can be understood in terms of charge neutrality levels. These are also related to states due to interstitial hydrogen.
A visual‐search model observer for multislice‐multiview SPECT images
Authors: Gifford Howard C.
Published: August 2013

Purpose:

Mathematical model observers are intended for efficient assessment of diagnostic image quality, but model‐observer studies often are not representative of clinical realities. Model observers based on a visual‐search (VS) paradigm may allow for greater clinical relevance. The author has compared the performances of several VS model observers with those of human observers and an existing scanning model observer for a study involving nodule detection and localization in simulated Tc‐99m single‐photon emission computed tomography (SPECT) lung volumes.

Methods:

A localization receiver operating characteristic (LROC) study compared two iterative SPECT reconstruction strategies: an all‐corrections (AllC) strategy with compensations for attenuation, scatter, and distance‐dependent camera resolution and an “RC” strategy with resolution compensation only. Nodules in the simulation phantom were of three different relative contrasts. Observers in the study had access to the coronal, sagittal, and transverse displays of the reconstructed volumes. Three human observers each read 50 training volumes and 100 test volumes per reconstruction strategy. The same images were analyzed by a channelized nonprewhitening (CNPW) scanning observer and two VS observers. The VS observers implemented holistic search processes that identified focal points of Tc‐99m uptake for subsequent analysis by the CNPW scanning model. The level of prior knowledge about the background structure in the images was a study variable for the model observers. Performance was scored by area under the LROC curve.

Results:

The average human‐observer performances were respectively 0.67 ± 0.04 and 0.61 ± 0.03 for the RC and AllC strategies. Given approximate knowledge about the background structure, both VS models scored 0.69 ± 0.08 (RC) and 0.66 ± 0.08 (AllC). The scanning observer reversed the strategy ranking in scoring 0.73 ± 0.08 with the AllC strategy and 0.64 ± 0.08 with the RC strategy. The VS observers exhibited less sensitivity to variations in background knowledge compared to the scanning observer.

Conclusions:

The VS framework has the potential to increase the clinical similitude of model‐observer studies and to enhance the ability of existing model observers to quantitatively predict human‐observer performance.
Maternal Hyperglycemia Activates an ASK1–FoxO3a–Caspase 8 Pathway That Leads to Embryonic Neural Tube Defects
Authors: Yang Peixin , Li Xuezheng , Xu Cheng , Eckert Richard L. , Reece E. Albert , Zielke Horst Ronald , Wang Fang
Published: August 2013

Interference with a cell death–promoting signaling pathway could prevent neural tube defects in the children of diabetic women.
Activation Loop Dynamics Determine the Different Catalytic Efficiencies of B Cell– and T Cell–Specific Tec Kinases
Authors: Joseph Raji E. , Kleino Iivari , Wales Thomas E. , Xie Qian , Fulton D. Bruce , Engen John R. , Berg Leslie J. , Andreotti Amy H.
Published: August 2013

Just six amino acid residues prevent the T cell kinase Itk from being as active as its B cell counterpart, Btk.
Steroid Receptor Signaling
Authors: Hines Pamela J.
Published: August 2013

Crystal structures reveal why the brassinosteroid receptor kinase requires another kinase helper protein for activation.
ER-Derived ROS and Mitochondrial Dysfunction
Authors: VanHook Annalisa M.
Published: August 2013

The endoplasmic reticulum is the major source of reactive oxygen species in yeast with mitochondrial dysfunction.
Iatrogenic Cushing's Syndrome Induced by Posaconazole
Authors: Pilmis Benoit , Coignard-Biehler Hélène , Jullien Vincent , Hermine Olivier , Touraine Philippe , Lecuit Marc , Lortholary Olivier
Published: August 2013

Iatrogenic Cushing's syndrome is an undesirable outcome of glucocorticoids treatment. It can be increased by pharmacologic interactions. Glucocorticoid therapy, given in association with ritonavir, and some azole treatments are causes of iatrogenic Cushing's syndrome. We present a patient with common-variable immunodeficiency who received 7 years of itraconazole therapy for bronchial colonization with
Aspergillus
in combination with inhaled fluticasone without any Cushingoid symptoms. After a switch to posaconazole, the patient developed Cushingoid symptoms.
Evaluation of Intravenous Anthrax Immune Globulin for Treatment of Inhalation Anthrax
Authors: Mytle Nutan , Hopkins Robert J. , Malkevich Nina V. , Basu Subhendu , Meister Gabriel T. , Sanford Daniel C. , Comer Jason E. , Van Zandt Kristopher E. , Al-Ibrahim Mohamed , Kramer William G. , Howard Cris , Daczkowski Nancy , Chakrabarti Ajoy C. , Ionin Boris , Nabors Gary S. , Skiadopoulos Mario H.
Published: August 2013

Bacillus anthracis
toxins can be neutralized by antibodies against protective antigen (PA), a component of anthrax toxins. Anthrivig (human anthrax immunoglobulin), also known as AIGIV, derived from plasma of humans immunized with BioThrax (anthrax vaccine adsorbed), is under development for the treatment of toxemia following exposure to anthrax spores. The pharmacokinetics (PK) of AIGIV was assessed in naive animals and healthy human volunteers, and the efficacy of AIGIV was assessed in animals exposed via inhalation to aerosolized
B. anthracis
spores. In the clinical study, safety, tolerability, and PK were evaluated in three dose cohorts (3.5, 7.1, and 14.2 mg/kg of body weight of anti-PA IgG) with 30 volunteers per cohort. The elimination half-life of AIGIV in rabbits, nonhuman primates (NHPs), and humans following intravenous infusion was estimated to be approximately 4, 12, and 24 days, respectively, and dose proportionality was observed. In a time-based treatment study, AIGIV protected 89 to 100% of animals when administered 12 h postexposure; however, a lower survival rate of 39% was observed when animals were treated 24 h postexposure, underscoring the need for early intervention. In a separate set of studies, animals were treated on an individual basis upon detection of a clinical sign or biomarker of disease, namely, a significant increase in body temperature (SIBT) in rabbits and presence of PA in the serum of NHPs. In these trigger-based intervention studies, AIGIV induced up to 75% survival in rabbits depending on the dose and severity of toxemia at the time of treatment. In NHPs, up to 33% survival was observed in AIGIV-treated animals. (The clinical study has been registered at
ClinicalTrials.gov
under registration no. NCT00845650.)
Transdermal Glyceryl Trinitrate as an Effective Adjunctive Treatment with Artemether for Late-Stage Experimental Cerebral Malaria
Authors: Orjuela-Sánchez Pamela , Ong Peng Kai , Zanini Graziela M. , Melchior Benoît , Martins Yuri C. , Meays Diana , Frangos John A. , Carvalho Leonardo J. M.
Published: August 2013

Cerebral malaria (CM) is associated with low nitric oxide (NO) bioavailability, cerebrovascular constriction, occlusion, and hypoperfusion. Administration of exogenous NO partially prevents the neurological syndrome and associated vascular pathology in an experimental CM (ECM) mouse model. In this study, we evaluated the effects of transdermal glyceryl trinitrate in preventing ECM and, in combination with artemether, rescuing late-stage ECM mice from mortality. The glyceryl trinitrate and/or artemether effect on survival and clinical recovery was evaluated in C57BL/6 mice infected with
P. berghei
ANKA. NO synthase (NOS) expression in mouse brain was determined by Western blots. Mean arterial pressure (MAP) and pial arteriolar diameter were monitored using a tail-cuff blood pressure system and a cranial window preparation, respectively. Preventative administration of glyceryl trinitrate at 0.025 mg/h decreased ECM mortality from 67 to 11% and downregulated inducible NOS expression in the brain. When administered as adjunctive rescue therapy with artemether, glyceryl trinitrate increased survival from 47 to 79%. The adjunctive therapy caused a sustained reversal of pial arteriolar vasoconstriction in ECM mice, an effect not observed with artemether alone. Glyceryl trinitrate induced a 13% decrease in MAP in uninfected mice but did not further affect MAP in hypotensive ECM mice. Glyceryl trinitrate, when combined with artemether, was an effective adjunctive rescue treatment for ECM. This treatment ameliorated pial arteriolar vasospasm and did not significantly affect MAP. These results indicate that transdermal glyceryl trinitrate has potential to be considered as a candidate for adjunctive therapy for CM.
Bioengineered Lysozyme Reduces Bacterial Burden and Inflammation in a Murine Model of Mucoid Pseudomonas aeruginosa Lung Infection
Authors: Teneback Charlotte C. , Scanlon Thomas C. , Wargo Matthew J. , Bement Jenna L. , Griswold Karl E. , Leclair Laurie W.
Published: August 2013

The spread of drug-resistant bacterial pathogens is a growing global concern and has prompted an effort to explore potential adjuvant and alternative therapies derived from nature's repertoire of bactericidal proteins and peptides. In humans, the airway surface liquid layer is a rich source of antibiotics, and lysozyme represents one of the most abundant and effective antimicrobial components of airway secretions. Human lysozyme is active against both Gram-positive and Gram-negative bacteria, acting through several mechanisms, including catalytic degradation of cell wall peptidoglycan and subsequent bacterial lysis. In the infected lung, however, lysozyme's dense cationic character can result in sequestration and inhibition by polyanions associated with airway inflammation. As a result, the efficacy of the native enzyme may be compromised in the infected and inflamed lung. To address this limitation, we previously constructed a charge-engineered variant of human lysozyme that was less prone to electrostatic-mediated inhibition
in vitro
. Here, we employ a murine model to show that this engineered enzyme is superior to wild-type human lysozyme as a treatment for mucoid
Pseudomonas aeruginosa
lung infections. The engineered enzyme effectively decreases the bacterial burden and reduces markers of inflammation and lung injury. Importantly, we found no evidence of acute toxicity or allergic hypersensitivity upon repeated administration of the engineered biotherapeutic. Thus, the charge-engineered lysozyme represents an interesting therapeutic candidate for
P. aeruginosa
lung infections.
Effect of a High-Calorie, High-Fat Meal on the Bioavailability and Pharmacokinetics of PA-824 in Healthy Adult Subjects
Authors: Winter Helen , Ginsberg Ann , Egizi Erica , Erondu Ngozi , Whitney Karl , Pauli Elliott , Everitt Daniel
Published: August 2013

PA-824 is a novel nitroimidazo-oxazine being developed as an antituberculosis agent. Two randomized studies evaluated the pharmacokinetics and safety of a single oral dose of PA-824 administered to healthy adult subjects 30 min after a high-calorie, high-fat meal (fed state) versus after a minimum 10-h fast (fasted state). A total of 48 subjects were dosed in the two studies in a randomized crossover design with PA-824 at dose levels of 50, 200, or 1,000 mg in the fed state or fasted state. After the administration of PA-824, the geometric mean ratios of
C
max
and AUC
0–∞
revealed an increase in exposure with the addition of a high-calorie, high-fat meal compared to the fasted state by 140 and 145% at 50 mg, 176 and 188% at 200 mg, and 450 and 473% at 50, 200, and 1,000 mg, respectively. The median
T
max
in the fed state was 4 h for the 50-mg dose and 5 h for the 200- and 1,000-mg doses. In the fasted state, the median
T
max
was 4 h for the 50- and 200-mg doses and 6.5 h for the 1,000-mg dose. All doses were well tolerated, and no serious adverse events occurred in either study. (This study has been registered at
ClinicalTrials.gov
under registration numbers NCT01828827 and NCT01830439.)
Human Herpesvirus 6 U69 Kinase Phosphorylates the Methylenecyclopropane Nucleosides Cyclopropavir, MBX 2168, and MBX 1616 to Their Monophosphates
Authors: Komazin-Meredith Gloria , Cardinale Steven C. , Williams John D. , Peet Norton P. , Prichard Mark N. , Bowlin Terry L.
Published: August 2013

Dihydroxymethyl and monohydroxymethyl methylenecyclopropane nucleosides are effective inhibitors of both variants of human herpesvirus 6 (HHV-6). We investigated involvement of HHV-6 U69 protein kinase in their mechanism of action. Phosphorylation of the dihydroxymethyl analogue cyclopropavir and monohydroxymethyl nucleosides with either a 6-ether moiety (MBX 2168) or a 6-thioether moiety (MBX 1616) with purified U69 was examined. All three compounds were substrates of this viral kinase and had similar Michaelis-Menten kinetic parameters.
In VitroCross-Resistance Profile of Nucleoside Reverse Transcriptase Inhibitor (NRTI) BMS-986001 against Known NRTI Resistance Mutations
Authors: Li Zhufang , Terry Brian , Olds William , Protack Tricia , Deminie Carol , Minassian Beatrice , Nowicka-Sans Beata , Sun Yongnian , Dicker Ira , Hwang Carey , Lataillade Max , Hanna George J. , Krystal Mark
Published: August 2013

BMS-986001 is a novel HIV nucleoside reverse transcriptase inhibitor (NRTI). To date, little is known about its resistance profile. In order to examine the cross-resistance profile of BMS-986001 to NRTI mutations, a replicating virus system was used to examine specific amino acid mutations known to confer resistance to various NRTIs. In addition, reverse transcriptases from 19 clinical isolates with various NRTI mutations were examined in the Monogram PhenoSense HIV assay. In the site-directed mutagenesis studies, a virus containing a K65R substitution exhibited a 0.4-fold change in 50% effective concentration (EC50) versus the wild type, while the majority of viruses with the Q151M constellation (without M184V) exhibited changes in EC50versus wild type of 0.23- to 0.48-fold. Susceptibility to BMS-986001 was also maintained in an L74V-containing virus (0.7-fold change), while an M184V-only-containing virus induced a 2- to 3-fold decrease in susceptibility. Increasing numbers of thymidine analog mutation pattern 1 (TAM-1) pathway mutations correlated with decreases in susceptibility to BMS-986001, while viruses with TAM-2 pathway mutations exhibited a 5- to 8-fold decrease in susceptibility, regardless of the number of TAMs. A 22-fold decrease in susceptibility to BMS-986001 was observed in a site-directed mutant containing the T69 insertion complex. Common non-NRTI (NNRTI) mutations had little impact on susceptibility to BMS-986001. The results from the site-directed mutants correlated well with the more complicated genotypes found in NRTI-resistant clinical isolates. Data from clinical studies are needed to determine the clinically relevant resistance cutoff values for BMS-986001.
High-Level Pacidamycin Resistance in Pseudomonas aeruginosa Is Mediated by an Opp Oligopeptide Permease Encoded by the
opp-fabI
Operon
Authors: Mistry Anita , Warren Mark S. , Cusick John K. , Karkhoff-Schweizer RoxAnn R. , Lomovskaya Olga , Schweizer Herbert P.
Published: August 2013

Pacidamycins (or uridyl peptide antibiotics) possess selective
in vivo
activity against
Pseudomonas aeruginosa
. An important limitation for the therapeutic use of pacidamycins with
P. aeruginosa
is the high frequency (10
−6
to 10
−7
) at which resistant mutants emerge. To elucidate the mechanism(s) of this resistance, pacidamycin-resistant
P. aeruginosa
mutants were isolated. Two types of mutants were obtained. Type 1, or high-level resistance mutants with a pacidamycin MIC of 512 μg/ml, were more abundant, with a frequency of ∼2 × 10
−6
, and did not show cross-resistance with other antibiotics. Type 2, low-level resistance mutants, were isolated with a frequency of ∼10
−8
and had a pacidamycin MIC of 64 μg/ml (the MIC for the wild-type strain was 4 to 16 μg/ml). These mutants were cross-resistant to levofloxacin, tetracycline, and erythromycin and were shown to overexpress either the MexAB-OprM or MexCD-OprJ multidrug resistance efflux pumps. High-level resistant mutants were isolated by transposon mutagenesis and one insertion was localized to
oppB
, one of two periplasmic binding protein components of an oligopeptide transport system which is encoded by the
opp-fabI
operon. The Opp system is required for uptake of pacidamycin across the inner membrane, since various
opp
, but not
fabI
, mutants were resistant to high levels of pacidamycin. Both of the two putative Opp periplasmic binding proteins, OppA and OppB, were required for pacidamycin uptake. Although both impaired uptake into and efflux from the cell can cause pacidamycin resistance in
P. aeruginosa
, our data suggest that impaired uptake is the primary reason for the high-frequency and high-level pacidamycin resistance.
Biological Markers of Pseudomonas aeruginosa Epidemic High-Risk Clones
Authors: Mulet Xavier , Cabot Gabriel , Ocampo-Sosa Alain A. , Domínguez M. Angeles , Zamorano Laura , Juan Carlos , Tubau Fe , Rodríguez Cristina , Moyà Bartolomé , Peña Carmen , Martínez-Martínez Luis , Oliver Antonio
Published: August 2013

A limited number of
Pseudomonas aeruginosa
genotypes (mainly ST-111, ST-175, and ST-235), known as high-risk clones, are responsible for epidemics of nosocomial infections by multidrug-resistant (MDR) or extensively drug-resistant (XDR) strains worldwide. We explored the potential biological parameters that may explain the success of these clones. A total of 20 isolates from each of 4 resistance groups (XDR, MDR, ModR [resistant to 1 or 2 classes], and MultiS [susceptible to all antipseudomonals]), recovered from a multicenter study of
P. aeruginosa
bloodstream infections performed in 10 Spanish hospitals, were analyzed. A further set of 20 XDR isolates belonging to epidemic high-risk clones (ST-175 [
n
= 6], ST-111 [
n
= 7], and ST-235 [
n
= 7]) recovered from different geographical locations was also studied. When unknown, genotypes were documented through multilocus sequence typing. The biological parameters evaluated included twitching, swimming, and swarming motility, biofilm formation, production of pyoverdine and pyocyanin, spontaneous mutant frequencies, and the
in vitro
competition index (CI) obtained with a flow cytometry assay. All 20 (100%) XDR, 8 (40%) MDR, and 1 (5%) ModR bloodstream isolate from the multicenter study belonged to high-risk clones. No significant differences were observed between clonally diverse ModR and MultiS isolates for any of the parameters. In contrast, MDR/XDR high-risk clones showed significantly increased biofilm formation and mutant frequencies but significantly reduced motility (twitching, swimming, and swarming), production of pyoverdine and pyocyanin, and fitness. The defined biological markers of high-risk clones, which resemble those resulting from adaptation to chronic infections, could be useful for the design of specific treatment and infection control strategies.
In Vitro
Activity of Ceftaroline-Avibactam against Gram-Negative and Gram-Positive Pathogens Isolated from Patients in Canadian Hospitals from 2010 to 2012: Results from the CANWARD Surveillance Study
Authors: Karlowsky James A. , Adam Heather J. , Baxter Melanie R. , Lagacé-Wiens Philippe R. S. , Walkty Andrew J. , Hoban Daryl J. , Zhanel George G.
Published: August 2013

The
in vitro
activities of ceftaroline-avibactam, ceftaroline, and comparative agents were determined for a collection of bacterial pathogens frequently isolated from patients seeking care at 15 Canadian hospitals from January 2010 to December 2012. In total, 9,758 isolates were tested by using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method (document M07-A9, 2012), with MICs interpreted by using CLSI breakpoints (document M100-S23, 2013). Ceftaroline-avibactam demonstrated potent activity (MIC
90
, ≤0.5 μg/ml) against
Escherichia coli
,
Klebsiella pneumoniae
,
Klebsiella oxytoca
,
Proteus mirabilis
,
Enterobacter cloacae
,
Enterobacter aerogenes
,
Serratia marcescens
,
Morganella morganii
,
Citrobacter freundii
, and
Haemophilus influenzae
; >99% of isolates of
E. coli
,
K. pneumoniae
,
K. oxytoca
,
P. mirabilis
,
M. morganii
,
C. freundii
, and
H. influenzae
were susceptible to ceftaroline-avibactam according to CLSI MIC interpretative criteria for ceftaroline. Ceftaroline was less active than ceftaroline-avibactam against all species of
Enterobacteriaceae
tested, with rates of susceptibility ranging from 93.9% (
P. mirabilis
) to 54.0% (
S. marcescens
). All isolates of methicillin-susceptible
Staphylococcus aureus
(MIC
90
, 0.25 μg/ml) and 99.6% of methicillin-resistant
S. aureus
isolates (MIC
90
, 1 μg/ml) were susceptible to ceftaroline; the addition of avibactam to ceftaroline did not alter its activity against staphylococci or streptococci. All isolates of
Streptococcus pneumoniae
(MIC
90
, 0.03 μg/ml),
Streptococcus pyogenes
(MIC
90
, ≤0.03 μg/ml), and
Streptococcus agalactiae
(MIC
90
, 0.015 μg/ml) tested were susceptible to ceftaroline. We conclude that combining avibactam with ceftaroline expanded its spectrum of activity to include most isolates of
Enterobacteriaceae
resistant to third-generation cephalosporins, including extended-spectrum β-lactamase (ESBL)- and AmpC-producing
E. coli
and ESBL-producing
K. pneumoniae
, while maintaining potent activity against staphylococci and streptococci.
Azole Resistance in Cryptococcus gattii from the Pacific Northwest: Investigation of the Role of
ERG11
Authors: Gast Charles E. , Basso Luiz R. , Bruzual Igor , Wong Brian
Published: August 2013

Cryptococcus gattii
is responsible for an expanding epidemic of serious infections in Western Canada and the Northwestern United States (Pacific Northwest). Some patients with these infections respond poorly to azole antifungals, and high azole MICs have been reported in Pacific Northwest
C. gattii
. In this study, multiple azoles (but not amphotericin B) had higher MICs for 25 Pacific Northwest
C. gattii
than for 34 non-Pacific Northwest
C. gattii
or 20
Cryptococcus neoformans
strains. We therefore examined the roles in azole resistance of overexpression of or mutations in the gene (
ERG11
) encoding the azole target enzyme.
ERG11
/
ACT1
mRNA ratios were higher in
C. gattii
than in
C. neoformans
, but these ratios did not differ in Pacific Northwest and non-Pacific Northwest
C. gattii
strains, nor did they correlate with fluconazole MICs within any group. Three Pacific Northwest
C. gattii
strains with low azole MICs and 2 with high azole MICs had deduced Erg11p sequences that differed at one or more positions from that of the fully sequenced Pacific Northwest
C. gattii
strain R265. However, the azole MICs for conditional
Saccharomyces cerevisiae
erg11
mutants expressing the 5 variant
ERG11
s were within 2-fold of the azole MICs for
S. cerevisiae
expressing the
ERG11
gene from
C. gattii
R265, non-Pacific Northwest
C. gattii
strain WM276, or
C. neoformans
strains H99 or JEC21. We conclude that neither
ERG11
overexpression nor variations in
ERG11
coding sequences was responsible for the high azole MICs observed for the Pacific Northwest
C. gattii
strains we studied.
In VitroEffects of Novel Ruthenium Complexes in Neospora caninum and Toxoplasma gondii Tachyzoites
Authors: Barna Fabienne , Debache Karim , Vock Carsten A. , Küster Tatiana , Hemphill Andrew
Published: August 2013

Upon the screening of 16 antiproliferative compounds againstToxoplasma gondiiandNeospora caninum, two hydrolytically stable ruthenium complexes (compounds 16 and 18) exhibited 50% inhibitory concentrations of 18.7 and 41.1 nM (T. gondii) and 6.7 and 11.3 nM (N. caninum). To achieve parasiticidal activity with compound 16, long-term treatment (22 to 27 days at 80 to 160 nM) was required. Transmission electron microscopy demonstrated the rapid impact on and ultrastructural alterations in both parasites. These preliminary findings suggest that the potential of ruthenium-based compounds should thus be further exploited.
The RNA Chaperone Hfq Is Required for Virulence of Bordetella pertussis
Authors: Bibova Ilona , Skopova Karolina , Masin Jiri , Cerny Ondrej , Hot David , Sebo Peter , Vecerek Branislav
Published: August 2013

Bordetella pertussisis a Gram-negative pathogen causing the human respiratory disease called pertussis or whooping cough. Here we examined the role of the RNA chaperone Hfq inB. pertussisvirulence. Hfq mediates interactions between small regulatory RNAs and their mRNA targets and thus plays an important role in posttranscriptional regulation of many cellular processes in bacteria, including production of virulence factors. We characterized anhfqdeletion mutant (Δhfq) ofB. pertussis18323 and show that the Δhfqstrain produces decreased amounts of the adenylate cyclase toxin that plays a central role inB. pertussisvirulence. Production of pertussis toxin and filamentous hemagglutinin was affected to a lesser extent.In vitro, the ability of the Δhfqstrain to survive within macrophages was significantly reduced compared to that of the wild-type (wt) strain. The virulence of the Δhfqstrain in the mouse respiratory model of infection was attenuated, with its capacity to colonize mouse lungs being strongly reduced and its 50% lethal dose value being increased by one order of magnitude over that of the wt strain. In mixed-infection experiments, the Δhfqstrain was then clearly outcompeted by the wt strain. This requirement for Hfq suggests involvement of small noncoding RNA regulation inB. pertussisvirulence.