bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of Leishmania donovani infectivity in whole blood using riboflavin and ultraviolet light
Authors: Tonnetti Laura , Thorp Aaron M. , Reddy Heather L. , Keil Shawn D. , Doane Suzann K. , Goodrich Raymond P. , Leiby David A.
Published: August 2014

Background

Leishmaniasis is a vector‐borne disease caused by the protozoan parasite Leishmania sp. that is transmitted by sandflies. Travelers to endemic areas, and US military personnel stationed in the Middle East, are at risk for contracting the disease.

Study Design and Methods

Whole blood (WB) units were spiked with human monocytes infected with L. donovani amastigotes to a final concentration of approximately 105 infected cells/mL. After riboflavin (RB) addition, units were exposed to 80 J/mLRBCs ultraviolet (UV) light. One pretreatment (collected after RB addition) and one posttreatment sample were collected, serially diluted in culture medium, and incubated at 22°C for up to 5 weeks. Parasite viability was determined by microscopic observation for replicating promastigote forms.

Results

Mirasol treatment of 3 units of L. donovani–infected WB with RB and UV light resulted in a parasite reduction of 2.3 ± 0.12 log.

Conclusions

Partial reduction of L. donovani can be achieved in WB using RB and UV light. This technology may be useful when potential donors are exposed to Leishmania sp. during residence, travel, or military deployment to an endemic area.
Novel alleles at the Kell blood group locus that lead to Kell variant phenotype in the Dutch population
Authors: Ji Yanli , Veldhuisen Barbera , Ligthart Peter , Haer‐Wigman Lonneke , Jongerius John , Boujnan Mohamed , Ait Soussan Aicha , Luo Guangping , Fu Yongshui , van der Schoot C. Ellen , de Haas Masja
Published: August 2014

Background

Alloantibodies directed against antigens of the Kell blood group system are clinically significant. In the Netherlands, the KEL1 antigen is determined in all blood donors. In this study, after phenotyping of KEL:1‐positive donors, genotyping analysis was conducted in KEL:1,–2 donors to identify possible KEL*02 variant alleles.

Study Design and Methods

A total of 407 donors with the KEL:1,–2 phenotype were genotyped for the KEL*01/02 polymorphism, followed by direct sequencing of the KEL gene if the KEL*02 allele was detected. Two K0 patients were also included. Transcript analysis was conducted in two probands with the KEL*02. M05 allele defined by a synonymous mutation (G573G). Flow cytometry analysis to determine the expression of Kell antigen was performed.

Results

Thirty KEL:1,–2 individuals (30/407, 7.4%) with discrepant KEL*01/02 genotype were identified. Seven novel alleles were identified: KEL*02(R86Q, R281W)mod, KEL*02(L133P)null, KEL*02(436delG)null, KEL*02(F418S)null, KEL*02(R492X)null, KEL*02(L611R)null, and KEL*02(R700X)null. Nine variant alleles described before were detected: KEL*02N.06, KEL*02N.15, KEL*02N.17, KEL*02N.19, KEL*02N.21, KEL*02M.02, KEL*02M.04, KEL*02M.05, and KEL*02(Q362K)mod. A transcript lacking Exon 16 was identified in two probands with the KEL*02M.05 allele as described before. Finally, flow cytometry analysis showed a decreased total Kell expression and a relatively increased KEL1 expression in individuals with the KEL:1,2null or KEL:1,2mod phenotype, compared to KEL:1,2 controls.

Conclusion

In 7.4% of a group of tested KEL:1,–2 Dutch donors, a KEL*02null or KEL*02mod allele was found. A relatively increased KEL1 antigen expression in KEL:1,2null and KEL:1,2mod individuals suggest that the expression of Kell‐XK complexes depends on the availability of the XK protein.
An age‐dependent ABO discrepancy between mother and baby reveals a novel Aweak allele
Authors: Storry Jill R. , Condon Jennifer , Hult Annika K. , Harrison Andrew , Jørgensen René , Olsson Martin L.
Published: August 2014

Background

Discrepancies in ABO grouping arise due to different reasons, posing a threat to patient safety. Underlying causes include mixed‐field agglutination after transfusion, chimerism, fetomaternal exchange, or inheritance of unusual alleles resulting in weak A/B antigen expression. Cord blood from the infant of a group A2B mother typed as group O, H+. Samples were investigated to elucidate this conundrum.

Study Design and Methods

Genomic DNA was analyzed by ABO genotyping and sequencing. Red blood cells (RBCs) were characterized by routine serology and flow cytometry. Glycosyltransferase structure was predicted with 3D‐modeling software.

Results

The mother genotyped as ABO*A1.01/B.01, and the baby, ABO*A1.01/O.01.01. Sequencing revealed a substitution, 311T>A, in the ABO*A1‐like allele, which predicts Ile104Asn. Flow cytometry demonstrated A antigen on the mother's RBCs equivalent to the A2 phenotype while no A was detectable on cord RBCs. However, blood from the 11‐month‐old child demonstrated markedly increased A expression, likely reflecting initiation of carbohydrate chain branching.

Conclusion

We unraveled a novel Aweak allele (ABO*AW.29) in a case of apparent nonmaternity. Residue 104 is far from the catalytic site and may be involved in stabilizing the glycosyltransferase by dimerization. Our data support that the group AB mother's B‐transferase stabilizes the altered A‐transferase by heterodimerization, exemplifying the allelic enhancement phenomenon.
THE SOCIOLOGY AND THEOLOGY OF CREATIONIST OBJECTIONS TO EVOLUTION: HOW BLOOD MARKS THE BOUNDS OF THE CHRISTIAN BODY
Authors: Rogers Eugene F.
Published: August 2014

The staying power of creationist objections to evolution needs explanation. It depends on the use of “blood” language. Both William Jennings Bryan and, a century later, Ken Ham connect evolution with the blood of predation and the blood of apes, and both also connect evolution with the blood of atonement. Drawing on Mary Douglas and Bettina Bildhauer, I suggest that blood becomes important to societies that image the social body on the human body. Blood reveals the body as porous and vulnerable and therefore needing social work to be constructed as whole and bounded. Blood is the place where society conducts this work. I conclude that blood language is ineliminable from Christian discourse and indeed from discourses that model the social on the individual body. The solution, I suggest, is not to avoid the language of blood, but to continue to use it in ways that broaden its focus from human sin to human and animal suffering.
A PEIRCEAN RESPONSE TO THE EVOLUTIONARY DEBUNKING OF MORAL KNOWLEDGE
Authors: Slater Gary
Published: August 2014

The evolutionary debunking argument advanced by Sharon Street, Michael Ruse, and Richard Joyce employs the logic of Paul Griffiths and John Wilkins to contend that humans cannot have knowledge of moral truths, since the evolutionary process that has produced our basic moral intuitions lacks causal connections to those (putative) truths. Yet this argument is self‐defeating, because its aim is the categorical, normative claim that we should suspend our moral beliefs in light of the discoveries about their non‐truth‐tracking origins, when it is precisely this claim that relies upon the normativity under attack. This article cites Charles S. Peirce (1839–1914) to argue that such self‐defeat can be avoided by expanding upon the basic structure of the argument put forth by Griffiths and Wilkins, provided that one embraces a version of realism that corresponds with Peirce's doctrine of final causation. So construed, final causation reconciles real generals (including real moral values) with natural selection and undergirds further speculation of moral facts within values per se.
ENTHEOGENS, MYSTICISM, AND NEUROSCIENCE
Authors: Cole‐Turner Ron
Published: August 2014

Entheogens or psychedelic drugs such as lysergic acid diethylamide (LSD) and psilocybin are associated with mystical states of experience. Drug laws currently limit research, but important new work is under way at major biomedical research facilities showing that entheogens reliably occasion mystical experiences and thereby allow research into brain states during these experiences. Are drug‐occasioned mystical experiences neurologically the same as more traditional mystical states? Are there phenomenological and theological differences? As this research goes forward and the public becomes more widely aware of its achievements, religious scholars and experts in science and religion will be called upon to interpret the philosophical and theological presuppositions that underpin this research and the significance of the findings that flow from it.
DEFINING “RELIGION” AS NATURAL: A CRITICAL INVITATION TO ROBERT McCAULEY
Authors: Aghapour Andrew Ali
Published: August 2014

Previous critics have argued that Robert McCauley defines religion and science selectively and arbitrarily, cutting them to fit his model in Why Religion Is Natural and Science Is Not. McCauley has responded that final definitions are “overrated” and that artificial distinctions can serve an important role in naturalistic investigation. I agree with this position but argue that a genealogy of the category of religion is crucial to the methodology that McCauley describes. Since the inherent ambiguity of religion will undermine any essential claims about its cognitive naturalness, I invite McCauley to consider how his research might investigate scientific and religious cognition in new terms.
EXPLANATORY MODESTY
Authors: McCauley Robert N.
Published: August 2014

Although I certainly have differences with some of my commentators, I am grateful for the time, effort, and attention that each has devoted to my book, Why Religion Is Natural and Science Is Not. They have helpfully pointed out features of my positions that need clarification and elaboration. I am also grateful to the editor of Zygon, Willem Drees, for this opportunity to undertake that task here.
ON THINKING THEOLOGICALLY ABOUT ANIMALS: A RESPONSE
Authors: Clough David
Published: August 2014

In response to evaluations of On Animals: Volume 1, Systematic Theology by Margaret Adams, Christopher Carter, David Fergusson, and Stephen Webb, this article argues that the theological reappraisals of key doctrines argued for in the book are important for an adequate theological discussion of animals. The article addresses critical points raised by these authors in relation to the creation of human beings in the image of God, the doctrine of the incarnation, the theological ordering of creatures, anthropocentrism, and the doctrine of God. It concludes that, given previous neglect, much more discussion by theologians is required in order to think better concerning the place of animals in Christian theology, but acting better toward fellow animal creatures is an important next step toward this goal.
Light extraction enhancement in GaN-based vertical light-emitting diodes with hemispherical bumps
Authors: Wang Yujin , Zhu Chuanrui , Shen Yan , Yang Haifang , Liu Zhe , Gu Changzhi , Liu Baoli , Xu Xiangang
Published: August 2014

Ion beam etching technology was applied to the surfaces of GaN-based vertical light-emitting diodes (V-LEDs). The ability to control morphology using this technology resulted in very uniform, hexagonal, closely packed hemispherical bumps on the n-type GaN layer. The textured V-LEDs showed a remarkable increase (130%) in light output power compared to the original, and no electrical deterioration was noted. This study demonstrates that ion beam etching is an effective approach for fabricating hemispherical bumps to achieve increased light extraction efficiency in GaN-based V-LEDs, and potentially other optical devices.
Development of a PET/Cerenkov‐light hybrid imaging system
Authors: Yamamoto Seiichi , Hamamura Fuka , Watabe Tadashi , Ikeda Hayato , Kanai Yasukazu , Watabe Hiroshi , Kato Katsuhiko , Ogata Yoshimune , Hatazawa Jun
Published: August 2014

Purpose:

Cerenkov‐light imaging is a new molecular imaging technology that detects visible photons from high‐speed electrons using a high sensitivity optical camera. However, the merit of Cerenkov‐light imaging remains unclear. If a PET/Cerenkov‐light hybrid imaging system were developed, the merit of Cerenkov‐light imaging would be clarified by directly comparing these two imaging modalities.

Methods:

The authors developed and tested a PET/Cerenkov‐light hybrid imaging system that consists of a dual‐head PET system, a reflection mirror located above the subject, and a high sensitivity charge coupled device (CCD) camera. The authors installed these systems inside a black box for imaging the Cerenkov‐light. The dual‐head PET system employed a 1.2 × 1.2 × 10 mm3 GSO arranged in a 33 × 33 matrix that was optically coupled to a position sensitive photomultiplier tube to form a GSO block detector. The authors arranged two GSO block detectors 10 cm apart and positioned the subject between them. The Cerenkov‐light above the subject is reflected by the mirror and changes its direction to the side of the PET system and is imaged by the high sensitivity CCD camera.

Results:

The dual‐head PET system had a spatial resolution of ∼1.2 mm FWHM and sensitivity of ∼0.31% at the center of the FOV. The Cerenkov‐light imaging systemˈs spatial resolution was ∼275μm for a 22Na point source. Using the combined PET/Cerenkov‐light hybrid imaging system, the authors successfully obtained fused images from simultaneously acquired images. The image distributions are sometimes different due to the light transmission and absorption in the body of the subject in the Cerenkov‐light images. In simultaneous imaging of rat, the authors found that 18F‐FDG accumulation was observed mainly in the Harderian gland on the PET image, while the distribution of Cerenkov‐light was observed in the eyes.

Conclusions:

The authors conclude that their developed PET/Cerenkov‐light hybrid imaging system is useful to evaluate the merits and the limitations of Cerenkov‐light imaging in molecular imaging research.
Incorporating learning goals about modeling into an upper-division physics laboratory experiment
Authors: Zwickl Benjamin M. , Finkelstein Noah , Lewandowski H. J.
Published: August 2014

Implementing a laboratory activity involves a complex interplay among learning goals, available resources, feedback about the existing course, best practices for teaching, and an overall philosophy about teaching labs. Building on our previous work, which described a process of transforming an entire lab course, we now turn our attention to how an individual lab activity on the polarization of light was redesigned to include a renewed emphasis on one broad learning goal: modeling. By using this common optics lab as a concrete case study of a broadly applicable approach, we highlight many aspects of the activity development and show how modeling is used to integrate sophisticated conceptual and quantitative reasoning into the experimental process through the various aspects of modeling: constructing models, making predictions, interpreting data, comparing measurements with predictions, and refining models. One significant outcome is a natural way to integrate an analysis and discussion of systematic error into a lab activity.
Near field of an oscillating electric dipole and cross-polarization of a collimated beam of light: Two sides of the same coin
Authors: Aiello Andrea , Ornigotti Marco
Published: August 2014

We address the question of whether there exists a hidden relationship between the near-field distribution generated by an oscillating electric dipole and the so-called cross-polarization of a collimated beam of light. We find that the answer is affirmative by showing that the complex field distributions occurring in both cases have a common physical origin: the requirement that the electromagnetic fields must be transverse.
The electromagnetic momentum of static charge-current distributions
Authors: Franklin Jerrold
Published: August 2014

The origin of electromagnetic momentum for general static charge-current distributions is examined. The electromagnetic momentum for static electromagnetic fields is derived by implementing conservation of momentum for the sum of mechanical momentum and electromagnetic momentum. The external force required to keep matter at rest during the production of the final static configuration produces the electromagnetic momentum. Examples of the electromagnetic momentum in static electric and magnetic fields are given. The center-of-energy theorem is shown to be violated by electromagnetic momentum. Hidden momentum is shown to be generally absent and not to cancel electromagnetic momentum.
Influence of boundary conditions on the existence and stability of minimal surfaces of revolution made of soap films
Authors: Salkin Louis , Schmit Alexandre , Panizza Pascal , Courbin Laurent
Published: August 2014

Because of surface tension, soap films seek the shape that minimizes their surface energy and thus their surface area. This mathematical postulate allows one to predict the existence and stability of simple minimal surfaces. After briefly recalling classical results obtained in the case of symmetric catenoids that span two circular rings with the same radius, we discuss the role of boundary conditions on such shapes, working with two rings having different radii. We then investigate the conditions of existence and stability of other shapes that include two portions of catenoids connected by a planar soap film and half-symmetric catenoids for which we introduce a method of observation. We report a variety of experimental results including metastability—an hysteretic evolution of the shape taken by a soap film—explained using simple physical arguments. Working by analogy with the theory of phase transitions, we conclude by discussing universal behaviors of the studied minimal surfaces in the vicinity of their existence thresholds.
Why students still can't solve physics problems after solving over 2000 problems
Authors: Byun Taejin , Lee Gyoungho
Published: August 2014

This study investigates the belief that solving a large number of physics problems helps students better learn physics. We investigated the number of problems solved, student confidence in solving these problems, academic achievement, and the level of conceptual understanding of 49 science high school students enrolled in upper-level physics classes from Spring 2010 to Summer 2011. The participants solved an average of 2200 physics problems before entering high school. Despite having solved so many problems, no statistically significant correlation was found between the number of problems solved and academic achievement on either a mid-term or physics competition examination. In addition, no significant correlation was found between the number of physics problems solved and performance on the Force Concept Inventory (FCI). Lastly, four students were selected from the 49 participants with varying levels of experience and FCI scores for a case study. We determined that their problem solving and learning strategies was more influential in their success than the number of problems they had solved.
T cell receptor stimulation impairs IL-7 receptor signaling by inducing expression of the microRNA
miR-17
to target Janus kinase 1
Authors: Katz Gil , Pobezinsky Leonid A. , Jeurling Susanna , Shinzawa Miho , Van Laethem Francois , Singer Alfred
Published: August 2014

Induction of a microRNA that targets a critical kinase enables the T cell receptor to inhibit cytokine receptor signaling.
Diacylglycerol kinase α establishes T cell polarity by shaping diacylglycerol accumulation at the immunological synapse
Authors: Chauveau Anne , Le Floc’h Audrey , Bantilan Niels S. , Koretzky Gary A. , Huse Morgan
Published: August 2014

Corralling a lipid second messenger within a focused zone in T cells ensures their efficient activation by antigen-presenting cells.
Phenyl-1-Pyridin-2yl-Ethanone-Based Iron Chelators Increase IκB-α Expression, Modulate CDK2 and CDK9 Activities, and Inhibit HIV-1 Transcription
Authors: Kumari Namita , Iordanskiy Sergey , Kovalskyy Dmytro , Breuer Denitra , Niu Xiaomei , Lin Xionghao , Xu Min , Gavrilenko Konstantin , Kashanchi Fatah , Dhawan Subhash , Nekhai Sergei
Published: August 2014

HIV-1 transcription is activated by the Tat protein, which recruits CDK9/cyclin T1 to the HIV-1 promoter. CDK9 is phosphorylated by CDK2, which facilitates formation of the high-molecular-weight positive transcription elongation factor b (P-TEFb) complex. We previously showed that chelation of intracellular iron inhibits CDK2 and CDK9 activities and suppresses HIV-1 transcription, but the mechanism of the inhibition was not understood. In the present study, we tested a set of novel iron chelators for the ability to inhibit HIV-1 transcription and elucidated their mechanism of action. Novel phenyl-1-pyridin-2yl-ethanone (PPY)-based iron chelators were synthesized and examined for their effects on cellular iron, HIV-1 inhibition, and cytotoxicity. Activities of CDK2 and CDK9, expression of CDK9-dependent and CDK2-inhibitory mRNAs, NF-κB expression, and HIV-1- and NF-κB-dependent transcription were determined. PPY-based iron chelators significantly inhibited HIV-1, with minimal cytotoxicity, in cultured and primary cells chronically or acutely infected with HIV-1 subtype B, but they had less of an effect on HIV-1 subtype C. Iron chelators upregulated the expression of IκB-α, with increased accumulation of cytoplasmic NF-κB. The iron chelators inhibited CDK2 activity and reduced the amount of CDK9/cyclin T1 in the large P-TEFb complex. Iron chelators reduced HIV-1 Gag and Env mRNA synthesis but had no effect on HIV-1 reverse transcription. In addition, iron chelators moderately inhibited basal HIV-1 transcription, equally affecting HIV-1 and Sp1- or NF-κB-driven transcription. By virtue of their involvement in targeting several key steps in HIV-1 transcription, these novel iron chelators have the potential for the development of new therapeutics for the treatment of HIV-1 infection.
In Vivo
Monitoring of Staphylococcus aureus Biofilm Infections and Antimicrobial Therapy by [
18
F]Fluoro-Deoxyglucose–MicroPET in a Mouse Model
Authors: Garrido Victoria , Collantes María , Barberán Montserrat , Peñuelas Iván , Arbizu Javier , Amorena Beatriz , Grilló María-Jesús
Published: August 2014

A mouse model was developed for
in vivo
monitoring of infection and the effect of antimicrobial treatment against
Staphylococcus aureus
biofilms, using the [
18
F]fluoro-deoxyglucose–MicroPET ([
18
F]FDG-MicroPET) image technique. In the model, sealed Vialon catheters were briefly precolonized with
S. aureus
strains ATCC 15981 or V329, which differ in cytotoxic properties and biofilm matrix composition. After subcutaneous implantation of catheters in mice, the
S. aureus
strain differences found in bacterial counts and the inflammatory reaction triggered were detected by the regular bacteriological and histological procedures and also by [
18
F]FDG-MicroPET image signal intensity determinations in the infection area and regional lymph node. Moreover, [
18
F]FDG-MicroPET imaging allowed the monitoring of the rifampin treatment effect, identifying the periods of controlled infection and those of reactivated infection due to the appearance of bacteria naturally resistant to rifampin. Overall, the mouse model developed may be useful for noninvasive
in vivo
determinations in studies on
S. aureus
biofilm infections and assessment of new therapeutic approaches.
The
msaABCR
Operon Regulates Resistance in Vancomycin-Intermediate Staphylococcus aureus Strains
Authors: Samanta Dhritiman , Elasri Mohamed O.
Published: August 2014

Vancomycin-intermediate
Staphylococcus aureus
(VISA) strains present an increasingly difficult problem in terms of public health. However, the molecular mechanism for this resistance is not yet understood. In this study, we define the role of the
msaABCR
operon in vancomycin resistance in three clinical VISA strains, i.e., Mu50, HIP6297, and LIM2. Deletion of the
msaABCR
operon resulted in significant decreases in the vancomycin MIC (from 6.25 to 1.56 μg/ml) and significant reductions of cell wall thickness in strains Mu50 and HIP6297. Growth of the mutants in medium containing vancomycin at concentrations greater than 2 μg/ml resulted in decreases in the growth rate, compared with the wild-type strains. Mutation of the
msaABCR
operon also reduced the binding capacity for vancomycin. We conclude that the
msaABCR
operon contributes to resistance to vancomycin and cell wall synthesis in
S. aureus
.
Effect of Fosamprenavir-Ritonavir on the Pharmacokinetics of Dolutegravir in Healthy Subjects
Authors: Song Ivy , Borland Julie , Chen Shuguang , Peppercorn Amanda , Wajima Toshihiro , Piscitelli Stephen C.
Published: August 2014

Dolutegravir (DTG) is an HIV integrase inhibitor (INI) with demonstrated activity in INI-naive and INI-resistant patients. The objective of this open-label, 2-period, single-sequence study was to evaluate the effect of fosamprenavir-ritonavir (FPV-RTV) on the steady-state plasma pharmacokinetics of DTG. Twelve healthy subjects received 50 mg DTG once daily for 5 days (period 1), followed by 10 days of 50 mg DTG once daily in combination with 700/100 mg FPV-RTV every 12 h (period 2). All doses were administered in the fasting state. Serial pharmacokinetic samples for DTG and amprenavir and safety assessments were obtained throughout the study. Noncompartmental pharmacokinetic analysis was performed, and geometric least-squares mean ratios and 90% confidence intervals were generated for within-subject treatment comparison. Fosamprenavir-ritonavir decreased the DTG area under the concentration-time curve, maximum concentration in plasma, and concentration in plasma at the end of the dosing interval by 35%, 24%, and 49%, respectively. Both DTG and DTG with FPV-RTV were well tolerated; no subject withdrew because of adverse events. The most frequently reported drug-related adverse events were rash, abnormal dreams, and nasopharyngitis. The modest decrease in DTG exposure when it was coadministered with FPV-RTV is not considered clinically significant, and DTG dose adjustment is not required with coadministration of FPV-RTV in INI-naive patient populations on the basis of established “no-effect” boundaries of DTG. In the INI-resistant population, as a cautionary measure, alternative combinations that do not include FPV-RTV should be considered. (This study has been registered at
ClinicalTrials.gov
under identifier NCT01209065.)
Plasmodium falciparum and Plasmodium vivax Genotypes and Efficacy of Intermittent Preventive Treatment in Papua New Guinea
Authors: Barnadas Celine , Senn Nicolas , Iga Jonah , Timinao Lincoln , Javati Sarah , Malau Elisheba , Rarau Patricia , Reeder John C. , Siba Peter , Karunajeewa Harin , Zimmerman Peter A. , Davis Timothy M. , Mueller Ivo
Published: August 2014

Intermittent preventive treatment of infants (IPTi) reduces early childhood malaria-related morbidity. While genotypic drug resistance markers have proven useful in predicting the efficacy of antimalarial drugs in case management, there are few equivalent data relating to their protective efficacy when used as IPTi. The present data from an IPTi trial in Papua New Guinea demonstrate how these markers can predict protective efficacy of IPTi for both
Plasmodium falciparum
and
Plasmodium vivax
.
Linezolid-Resistant Staphylococcus aureus Strain 1128105, the First Known Clinical Isolate Possessing thecfrMultidrug Resistance Gene
Authors: Locke Jeffrey B. , Zuill Douglas E. , Scharn Caitlyn R. , Deane Jennifer , Sahm Daniel F. , Denys Gerald A. , Goering Richard V. , Shaw Karen J.
Published: August 2014

The Cfr methyltransferase confers resistance to six classes of drugs which target the peptidyl transferase center of the 50S ribosomal subunit, including some oxazolidinones, such as linezolid (LZD). The mobilecfrgene was identified in European veterinary isolates from the late 1990s, although the earliest report of a clinicalcfr-positive strain was the 2005 Colombian methicillin-resistantStaphylococcus aureus(MRSA) isolate CM05. Here, through retrospective analysis of LZDrclinical strains from a U.S. surveillance program, we identified acfr-positive MRSA isolate, 1128105, from January 2005, predating CM05 by 5 months. Molecular typing of 1128105 revealed a unique pulsed-field gel electrophoresis (PFGE) profile most similar to that of USA100,spatype t002, and multilocus sequence type 5 (ST5). In addition tocfr, LZD resistance in 1128105 is partially attributed to the presence of a single copy of the 23S rRNA gene mutation T2500A. Transformation of the ∼37-kb conjugative p1128105cfr-bearing plasmid from 1128105 intoS. aureusATCC 29213 background strains was successful in recapitulating the Cfr antibiogram, as well as resistance to aminoglycosides and trimethoprim. A 7-kbcfr-containing region of p1128105 possessed sequence nearly identical to that found in the Chinese veterinaryProteus vulgarisisolate PV-01 and in U.S. clinicalS. aureusisolate 1900, although the presence of IS431-like sequences is unique to p1128105. Thecfrgene environment in this early clinicalcfr-positive isolate has now been identified in Gram-positive and Gram-negative strains of clinical and veterinary origin and has been associated with multiple mobile elements, highlighting the versatility of this multidrug resistance gene and its potential for further dissemination.
Population Pharmacokinetics of Ciprofloxacin in Neonates and Young Infants Less than Three Months of Age
Authors: Zhao Wei , Hill Helen , Le Guellec Chantal , Neal Tim , Mahoney Sarah , Paulus Stephane , Castellan Charlotte , Kassai Behrouz , van den Anker Johannes N. , Kearns Gregory L. , Turner Mark A. , Jacqz-Aigrain Evelyne
Published: August 2014

Ciprofloxacin is used in neonates with suspected or documented Gram-negative serious infections. Currently, its use is off-label partly because of lack of pharmacokinetic studies. Within the FP7 EU project TINN (Treat Infection in NeoNates), our aim was to evaluate the population pharmacokinetics of ciprofloxacin in neonates and young infants <3 months of age and define the appropriate dose in order to optimize ciprofloxacin treatment in this vulnerable population. Blood samples were collected from neonates treated with ciprofloxacin and concentrations were quantified by high-pressure liquid chromatography–mass spectrometry. Population pharmacokinetic analysis was performed using NONMEM software. The data from 60 newborn infants (postmenstrual age [PMA] range, 24.9 to 47.9 weeks) were available for population pharmacokinetic analysis. A two-compartment model with first-order elimination showed the best fit with the data. A covariate analysis identified that gestational age, postnatal age, current weight, serum creatinine concentration, and use of inotropes had a significant impact on ciprofloxacin pharmacokinetics. Monte Carlo simulation demonstrated that 90% of hypothetical newborns with a PMA of <34 weeks treated with 7.5 mg/kg twice daily and 84% of newborns with a PMA ≥34 weeks and young infants receiving 12.5 mg/kg twice daily would reach the AUC/MIC target of 125, using the standard EUCAST MIC susceptibility breakpoint of 0.5 mg/liter. The associated risks of overdose for the proposed dosing regimen were <8%. The population pharmacokinetics of ciprofloxacin was evaluated in neonates and young infants <3 months old, and a dosing regimen was established based on simulation.
PBP2a Mutations Causing High-Level Ceftaroline Resistance in Clinical Methicillin-Resistant Staphylococcus aureus Isolates
Authors: Long S. Wesley , Olsen Randall J. , Mehta Shrenik C. , Palzkill Timothy , Cernoch Patricia L. , Perez Katherine K. , Musick William L. , Rosato Adriana E. , Musser James M.
Published: August 2014

Ceftaroline is the first member of a novel class of cephalosporins approved for use in the United States. Although prior studies have identified eight ceftaroline-resistant methicillin-resistant
Staphylococcus aureus
(MRSA) isolates in Europe and Asia with MICs ranging from 4 to 8 mg/liter, high-level resistance to ceftaroline (>32 mg/liter) has not been described in MRSA strains isolated in the United States. We isolated a ceftaroline-resistant (MIC > 32 mg/liter) MRSA strain from the blood of a cystic fibrosis patient and five MRSA strains from the respiratory tract of this patient. Whole-genome sequencing identified two amino acid-altering mutations uniquely present in the ceftaroline-binding pocket of the transpeptidase region of penicillin-binding protein 2a (PBP2a) in ceftaroline-resistant isolates. Biochemical analyses and the study of isogenic mutant strains confirmed that these changes caused ceftaroline resistance. Thus, we identified the molecular mechanism of ceftaroline resistance in the first MRSA strain with high-level ceftaroline resistance isolated in the United States.
Efficacy of Entecavir-Tenofovir Combination Therapy for Chronic Hepatitis B Patients with Multidrug-Resistant Strains
Authors: Lee Yun Bin , Lee Jeong-Hoon , Lee Dong Hyeon , Cho Hyeki , Ahn Hongkeun , Choi Won-Mook , Cho Young Youn , Lee Minjong , Yoo Jeong-Ju , Cho Yuri , Cho Eun Ju , Yu Su Jong , Kim Yoon Jun , Yoon Jung-Hwan , Kim Chung Yong , Lee Hyo-Suk
Published: August 2014

The emergence of multidrug-resistant (MDR) strains of hepatitis B virus (HBV) is a major concern. This study aimed to investigate the efficacy and safety of combination therapy with entecavir (ETV) plus tenofovir disoproxil fumarate (TDF) against MDR HBV. To adjust for differences in baseline characteristics, inverse probability weighting (IPW) using propensity scores for the entire cohort and weighted Cox proportional hazards models were applied. Ninety-three consecutive patients who were treated with ETV-TDF combination therapy for >6 months were included; at baseline, 45 were infected with HBV strains with genotypic resistance to lamivudine (LAM) and ETV (the LAM/ETV-R group), 28 with strains resistant to LAM and adefovir (ADV) (the LAM/ADV-R group), and 20 with strains resistant to LAM, ETV, and ADV (the LAM/ETV/ADV-R group). The median duration of rescue therapy was 13.0 (range, 6.7 to 31.7) months. Seventy-four of 93 patients (79.6%) achieved complete virologic suppression, after a median of 4.5 (95% confidence interval, 3.0 to 6.0) months. The cumulative probability of complete virologic suppression at month 6 was 63.6% (55.7%, 75.0%, and 65.0% in the LAM/ETV-R, LAM/ADV-R, and LAM/ETV/ADV-R groups, respectively). During the treatment period, these probabilities were not significantly different across the resistance profiles before and after IPW (P= 0.072 andP= 0.510, respectively). In multivariate analysis, a lower baseline HBV DNA level, but not resistance profiles, was an independent predictor of complete virologic suppression. Renal dysfunction was not observed during the treatment period. In conclusion, rescue therapy with ETV-TDF combination is efficient and safe in patients infected with MDR HBV strains regardless of the antiviral drug resistance profiles.
Dose Response of Listeria monocytogenes Invasion, Fetal Morbidity, and Fetal Mortality after Oral Challenge in Pregnant and Nonpregnant Mongolian Gerbils
Authors: Roulo Rebecca M. , Fishburn Jillian D. , Amosu Mayowa , Etchison Ashley R. , Smith Mary Alice
Published: August 2014

Listeria monocytogenes
is a food-borne pathogen that can result in adverse pregnancy outcomes, such as stillbirth or premature delivery. The Mongolian gerbil was recently proposed as the most appropriate small-animal model of listeriosis due to its susceptibility to the same invasion pathways as humans. The objectives of this study were to investigate invasion and adverse pregnancy outcomes in gerbils orally exposed to
L. monocytogenes
, to compare the dose-response data to those of other animal models, and to investigate differences in the responses of pregnant versus nonpregnant gerbils. Gerbils were orally exposed to 0 (control), 10
3
, 10
5
, 10
7
, or 10
9
CFU
L. monocytogenes
in whipping cream.
L. monocytogenes
was recovered in a dose-dependent manner from fecal samples, adult organs, and pregnancy-associated tissues. Dams exposed to 10
9
CFU had more invaded organs and higher concentrations of
L. monocytogenes
in almost all organs than nonpregnant animals, though no differences in fecal shedding were seen between the two groups. Adverse pregnancy outcomes occurred only in the dams treated with 10
9
CFU. A 50% infectivity dose (ID
50
) of 2.60 × 10
6
CFU for fetuses was calculated by fitting the data to a logistic model. Our results suggest that the 50% lethal dose (LD
50
) falls within the range of 5 × 10
6
to 5 × 10
8
CFU. This range includes the guinea pig and nonhuman primate LD
50
s, but the observation that
L. monocytogenes
-induced stillbirths can be seen in guinea pigs and primates exposed to lower doses than those at which stillbirths were seen in gerbils indicates that gerbils are not more sensitive to
L. monocytogenes
invasion.
SSP3 Is a Novel Plasmodium yoelii Sporozoite Surface Protein with a Role in Gliding Motility
Authors: Harupa Anke , Sack Brandon K. , Lakshmanan Viswanathan , Arang Nadia , Douglass Alyse N. , Oliver Brian G. , Stuart Andrew B. , Sather D. Noah , Lindner Scott E. , Hybiske Kevin , Torii Motomi , Kappe Stefan H. I.
Published: August 2014

Plasmodiumsporozoites develop within oocysts in the mosquito midgut wall and then migrate to the salivary glands. After transmission, they embark on a complex journey to the mammalian liver, where they infect hepatocytes. Proteins on the sporozoite surface likely mediate multiple steps of this journey, yet only a few sporozoite surface proteins have been described. Here, we characterize a novel, conserved sporozoite surface protein (SSP3) in the rodent malaria parasitePlasmodium yoelii. SSP3 is a putative type I transmembrane protein unique toPlasmodium. By using epitope tagging and SSP3-specific antibodies in conjunction with immunofluorescence microscopy, we showed that SSP3 is expressed in mosquito midgut oocyst sporozoites, exhibiting an intracellular localization. In sporozoites derived from the mosquito salivary glands, however, SSP3 localized predominantly to the sporozoite surface as determined by immunoelectron microscopy. However, the ectodomain of SSP3 appeared to be inaccessible to antibodies in nonpermeabilized salivary gland sporozoites. Antibody-induced shedding of the major surface protein circumsporozoite protein (CSP) exposed the SSP3 ectodomain to antibodies in some sporozoites. Targeted deletion ofSSP3adversely affectedin vitrosporozoite gliding motility, which, surprisingly, impacted neither their cell traversal capacity, host cell invasionin vitro, nor infectivityin vivo. Together, these data reveal a previously unappreciated complexity of thePlasmodiumsporozoite surface proteome and the roles of surface proteins in distinct biological activities of sporozoites.
Involvement of Stress-Related Genes
polB
and
PA14_46880
in Biofilm Formation of Pseudomonas aeruginosa
Authors: Alshalchi Sahar A. , Anderson Gregory G.
Published: August 2014

Chronic infections of
Pseudomonas aeruginosa
are generally established through production of biofilm. During biofilm formation, production of an extracellular matrix and establishment of a distinct bacterial phenotype make these infections difficult to eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behind
P. aeruginosa
biofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genes
polB
and
PA14_46880
reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the Δ
polB
and Δ
PA14_46880
strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression of
algR
, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation of
polB
and
PA14_46880
may inhibit transition of
P. aeruginosa
from a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding of
P. aeruginosa
biofilm formation and chronic biofilm infections.
Acidosis Potentiates the Host Proinflammatory Interleukin-1β Response to Pseudomonas aeruginosa Infection
Authors: Torres Iviana M. , Patankar Yash R. , Shabaneh Tamer B. , Dolben Emily , Hogan Deborah A. , Leib David A. , Berwin Brent L.
Published: August 2014

Infection byPseudomonas aeruginosa, and bacteria in general, frequently promotes acidification of the local microenvironment, and this is reinforced by pulmonary exertion and exacerbation. However, the consequence of an acidic environment on the host inflammatory response toP. aeruginosainfection is poorly understood. Here we report that the pivotal cellular and host proinflammatory interleukin-1β (IL-1β) response, which enables host clearance of the infection but can produce collateral inflammatory damage, is increased in response toP. aeruginosainfection within an acidic environment. Synergistic mechanisms that promote increased IL-1β release in response toP. aeruginosainfection in an acidic environment are increased pro-IL-1β induction and increased caspase-1 activity, the latter being dependent upon a functional type III secretion system of the bacteria and the NLRC4 inflammasome of the host. Using anin vivoperitonitis model, we have validated that the IL-1β inflammatory response is increased in mice in response toP. aeruginosainfection within an acidic microenvironment. These data reveal novel insights into the regulation and exacerbation of inflammatory responses toP. aeruginosa.
Immunoproteomic Analysis To Identify Shiga Toxin-Producing Escherichia coli Outer Membrane Proteins Expressed during Human Infection
Authors: Montero David , Orellana Paz , Gutiérrez Daniela , Araya Daniela , Salazar Juan Carlos , Prado Valeria , Oñate Ángel , del Canto Felipe , Vidal Roberto
Published: August 2014

Shiga-toxin producing
Escherichia coli
(STEC) is the etiologic agent of acute diarrhea, dysentery, and hemolytic-uremic syndrome (HUS). There is no approved vaccine for STEC infection in humans, and antibiotic use is contraindicated, as it promotes Shiga toxin production. In order to identify STEC-associated antigens and immunogenic proteins, outer membrane proteins (OMPs) were extracted from STEC O26:H11, O103, O113:H21, and O157:H7 strains, and commensal
E. coli
strain HS was used as a control. SDS-PAGE, two-dimensional-PAGE analysis, Western blot assays using sera from pediatric HUS patients and controls, and matrix-assisted laser desorption ionization–tandem time of flight analyses were used to identify 12 immunogenic OMPs, some of which were not reactive with control sera. Importantly, seven of these proteins have not been previously reported to be immunogenic in STEC strains. Among these seven proteins, OmpT and Cah displayed IgG and IgA reactivity with sera from HUS patients. Genes encoding these two proteins were present in a majority of STEC strains. Knowledge of the antigens produced during infection of the host and the immune response to those antigens will be important for future vaccine development.
The Acinetobacter baumannii Omp33-36 Porin Is a Virulence Factor That Induces Apoptosis and Modulates Autophagy in Human Cells
Authors: Rumbo Carlos , Tomás María , Fernández Moreira Esteban , Soares Nelson Cruz , Carvajal Micaela , Santillana Elena , Beceiro Alejandro , Romero Antonio , Bou Germán
Published: August 2014

Acinetobacter baumannii
is an extracellular opportunistic human pathogen that is becoming increasingly problematic in hospitals. In the present study, we demonstrate that the
A. baumannii
Omp 33- to 36-kDa protein (Omp33-36) is a porin that acts as a channel for the passage of water. The protein is found on the cell surface and is released along with other porins in the outer membrane vesicles (OMVs). In immune and connective cell tissue, this protein induced apoptosis by activation of caspases and modulation of autophagy, with the consequent accumulation of p62/SQSTM1 (sequestosome 1) and LC3B-II (confirmed by use of autophagy inhibitors). Blockage of autophagy enables the bacterium to persist intracellularly (inside autophagosomes), with the subsequent development of cytotoxicity. Finally, we used macrophages and a mouse model of systemic infection to confirm that Omp33-36 is a virulence factor in
A. baumannii
. Overall, the study findings show that Omp33-36 plays an important role in the pathogenesis of
A. baumannii
infections.
Monoclonal Antibodies against Vibrio vulnificus RtxA1 Elicit Protective Immunity through Distinct Mechanisms
Authors: Lee Tae Hee , Cha Sun-Shin , Lee Chang-Seop , Rhee Joon Haeng , Chung Kyung Min
Published: August 2014

Vibrio vulnificus
causes rapidly progressing septicemia with an extremely high mortality rate (≥50%), even with aggressive antibiotic treatment. The bacteria secrete multifunctional autoprocessing repeats-in-toxin (MARTX) toxins, which are involved in the pathogenesis of Gram-negative
Vibrio
species. Recently, we reported that immunization with the C-terminal region of
V. vulnificus
RtxA1/MARTX
Vv
, RtxA1-C, elicits a protective immune response against
V. vulnificus
through a poorly defined mechanism. In this study, we generated a panel of new monoclonal antibodies (MAbs) against
V. vulnificus
RtxA1-C and investigated their protective efficacies and mechanisms in a mouse model of infection. Prophylactic administration of seven MAbs strongly protected mice against lethal
V. vulnificus
infection (more than 90% survival). Moreover, three of these MAbs (21RA, 24RA, and 47RA) demonstrated marked efficacy as postexposure therapy. Notably, 21RA was therapeutically effective against lethal
V. vulnificus
infection by a variety of routes. Using Fab fragments and a neutropenic mouse model, we showed that 21RA and 24RA mediate protection from
V. vulnificus
infection through an Fc-independent and/or neutrophil-independent pathway. In contrast, 47RA-mediated protection was dependent on its Fc region and was reduced to 50% in neutropenic mice compared with 21RA-mediated and 24RA-mediated protection. Bacteriological study indicated that 21RA appears to enhance the clearance of
V. vulnificus
from the blood. Overall, these studies suggest that humoral immunity controls
V. vulnificus
infection through at least two different mechanisms. Furthermore, our panel of MAbs could provide attractive candidates for the further development of immunoprophylaxis/therapeutics and other therapies against
V. vulnificus
that target the MARTX toxin.