bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors relevant to pre‐veliger nutrition ofTridacnidae giant clams
Authors: Waters Charles G. , Lindsay Steve , Costello Mark J.
Published: August 2014

Tridacnid giant clams are of commercial interest for their nutritional, economic, and ecological significance throughout theIndo‐Pacific andOceania. A major impediment to culturing tridacnid giant clams is larval mortality, typically >96%. The effects of suspended and particulate nutrients on tridacnid veliger development have been examined, but factors relevant to the nutritional condition of oocytes and trochophore larvae are unknown. This is significant because the nutritional transition from trochophore to veliger coincides with rises in larval mortality. Our review examines culture techniques known to enhance gamete viability of several marine viable bivalves of commercial interest, and critically assesses whether such methods are applicable to tridacnids in culture conditions. Techniques for optimizing the nutritional requirements of pre‐veliger tridacnids such as broodstock conditioning by supplemental feeding, monitoring the condition of oocytes ready for release, water temperature, egg attributes such as size and biochemical composition, and nutrient loads in culture water chemistry are examined. We include suggestions for optimizing nutritional conditions from gametogenesis through embryonic development, and conclude with a primer of research opportunities based on gaps in our understanding of tridacnid pre‐veliger nutrition compared with other bivalves. A major conclusion is that culture protocols should include pre‐veliger nutritional fitness as a critical factor in enhancing larval survival, growth and development.
Effects of Prolonged in vitro Culture and Cryopreservation on Viability, DNA Fragmentation, Chromosome Stability and Ultrastructure of Bovine Cells from Amniotic Fluid and Umbilical Cord
Authors: da Cunha ER , Martins CF , Silva CG , Bessler HC , Báo SN
Published: August 2014

Contents

The objective of this work was to study cellular types that did not participated in the gastrulation process, amniotic fluid cells (AFCs) and umbilical cord cells (UCCs), in conditions of long‐term culture and cryopreserved with different solutions. The AFCs and UCCs were used in a comparative study with ear fibroblast cells (EFCs) that were cultured in vitro until 20 cellular passages and cryopreserved in 10% dimethylsulphoxide (DMSO), 5% dimethyl formamide (DMF) and 7% glycerol (Gly) solutions. The cellular viability, ultrastructure, DNA fragmentation and chromosome stability were evaluated to determine the cellular type most resistant. In all cell types, it was possible to evaluate the AFCs until 15 passages and UCCs until 20 passages with different periods of cellular growth to reach the confluence phase. Solutions containing 10% DMSO ensured viability of 90.33 ± 5.58%, 90.56 ± 4.40% and 81.90 ± 3.31%, respectively for EFCs, AFCs and UCCs, being significantly more efficient and with less variation than other cryoprotectant solutions. The AFCs were more sensitive to cryopreservation and presented low viability rate at the passage 20 (17.2 ± 8.87%). There was no change in karyotype and nuclear fragmentation was low in all cellular passages studied. With the scanning electron analysis was possible the characterization of AFCs and UCCs in suspension. The three cellular types of cells presented different shapes and characteristics on the surface. The results demonstrate that bovine AFCs and UCCs can be isolated, cultured in vitro and cryopreserved in 10% DMSO, not causing damage to DNA and chromosomes. The UCCs were more resistant than AFCs in all aspects.
Altered Expression of Transforming Growth Factor‐Beta Isoforms in Bovine Cystic Ovarian Disease
Authors: Matiller V , Stangaferro ML , Díaz PU , Ortega HH , Rey F , Huber E , Salvetti NR
Published: August 2014

Contents

Cystic ovarian disease (COD) is one of the main causes of infertility in dairy cattle. It has been shown that intra‐ovarian factors may contribute to follicular persistence. Transforming growth factor‐beta (TGFB) isoforms are important paracrine and autocrine signalling molecules that regulate ovarian follicle growth and physiology. Considering the importance of these factors in the ovarian physiology, in this study, we examined the expression of TGFB isoforms (TGFB1, TGFB2 and TGFB3) in the ovary of healthy cows and animals with spontaneous and adrenocorticotrophic hormone (ACTH)‐induced COD. In the oestrous‐synchronized control group, the expression of TGFB1 in granulosa and theca cells was higher in spontaneous cysts than in atretic or tertiary follicles. When we compared TGFB2 expression in granulosa cells from atretic or tertiary follicles from the oestrous‐synchronized control group with that in ACTH‐induced or spontaneous follicular cysts, we found a higher expression in the latter. The expression of the TGFB isoforms studied was also altered during folliculogenesis in both the spontaneous and ACTH‐induced COD groups. As it has been previously shown that TGFB influences steroidogenesis, ovarian follicular proliferation and apoptosis, an alteration in its expression may contribute to the pathogenesis of this disease.
A novel KIR2DL3 variant allele, KIR2DL3*031, identified from a southern Chinese Han individual
Authors: Zhao J. , Zhen J.‐X. , Deng Z.‐H.
Published: August 2014

The novel KIR2DL3*031 allele differs from KIR2DL3*00101 by a synonymous mutation and a non‐synonymous mutation.
Identity, Causality, and Pronoun Ambiguity
Authors: Sagi Eyal , Rips Lance J.
Published: August 2014

This article looks at the way people determine the antecedent of a pronoun in sentence pairs, such as: Albert invited Ron to dinner. He spent hours cleaning the house. The experiment reported here is motivated by the idea that such judgments depend on reasoning about identity (e.g., the identity of the he who cleaned the house). Because the identity of an individual over time depends on the causal‐historical path connecting the stages of the individual, the correct antecedent will also depend on causal connections. The experiment varied how likely it is that the event of the first sentence (e.g., the invitation) would cause the event of the second (the house cleaning) for each of the two individuals (the likelihood that if Albert invited Ron to dinner, this would cause Albert to clean the house, versus cause Ron to clean the house). Decisions about the antecedent followed causal likelihood. A mathematical model of causal identity accounted for most of the key aspects of the data from the individual sentence pairs.
Prediction of Erosion of Polyetherimide and Its Composites Using Response Surface Methodology
Authors: Thakre Avinash A.
Published: August 2014

This paper presents an approach to establish the model for predicting the steady-state erosion rate of polyetherimide and its glass fiber composites. Three-factor and two-level, face-centered composite design is used for experimentation. The parameters which affect the erosion rate are selected as glass fiber percentage (0–40%), impingement angle (30 deg–90 deg), and impact velocity (30–90 m/s). Response surface methodology is used to derive second-order quadratic model with interactions. Investigation showed all the parameters have significant effect on controlling steady-state erosion rate of these composites. The interactions of impact velocity-fiber percentage and impact velocity-impingement angle are significant. The increase in erosion rate with the increase in impact velocity is found to be satisfying a power law. Maximum erosion rate for these composites found at around 45 deg–60 deg impingement angle indicates their semiductile erosion behavior. Scanning electron microscopy photographs indicate ploughing, microcutting, development of cracks, and exposure of fibers as the dominating erosion mechanisms for these composites.
Order Tracking Analysis Using Generalized Fourier Transform With Nonorthogonal Basis
Authors: Alsalaet Jaafar , Najim Saleh , Ali Abduladhem
Published: August 2014

The nonorthogonal basis generalized Fourier transform is used as orders extraction technique during machinery speed-up and slow-down tests due to nonstationary nature of vibration signals in these tests. The kernels of this transform have time-dependent frequency which is related to the operating speed of the machine. Since these kernels may belong to different groups or shafts, they are generally nonorthogonal. The actual amplitudes and phases of the orders can be found by solving the system of linear equations resulting from decomposition process which is proposed in this work as an improvement to the time variant discrete Fourier transform (TVDFT) method. The proposed scheme is proved to be efficient and the processing time is very small as compared to other schemes such as the Vold–Kalman order tracking (VKOT) method. The accuracy and efficiency of the proposed scheme are investigated using simulated vibration signal and also actual signals.
Experimental Investigation of Nano-Biomaterial Applications for Heavy Oil Recovery in Shaly Porous Models: A Pore-Level Study
Authors: Mohebbifar Mahdi , Ghazanfari Mohammadi Hossein , Vossoughi Manouchehr
Published: August 2014

Application of nano or biomaterials for enhanced oil recovery (EOR) has been recently much attended by petroleum engineering researchers. However, how would be the displacement mechanisms and how would change the recovery efficiency while nano and biomaterials are used simultaneously is still an open question. To this end, a series of injection tests performed on micromodel containing shale strikes. Three types of biomaterials including biosurfactant, bioemulsifier, and biopolymer beside two types of nanoparticles including SiO2 and TiO2 at different concentrations were used as injection fluids. The microscopic as well as macroscopic efficiency of displacements were observed from analysis of images recorded during the tests. Microscopic observations revealed different mechanisms responsible for oil recovery including: wettability alteration, thinning oil film, interfacial tension (IFT) reduction, and water in oil emulsion formation. Contact angle experiments showed changes in the surface wetness from an oil-wet to neutral-wet/water-wet conditions when a layer of nano-biomaterial covered thin sections of a shaly sandstone. Also the results showed that the presence of shales causes early breakthrough and ultimate oil recovery reduction. Shales act as flow barriers and enhance injection fluid viscous fingering. Displacement efficiency in shaly systems is sharply related to the shale distribution. Oil recovery after breakthrough in shaly systems is progressive and considerable volume of oil in place is recovered after breakthrough. The highest efficiency, 78%, observed while injecting one pore volume of biopolymer and SiO2 nanoparticles. This work illustrates for the first time the mechanisms involved in nano-biomaterial-crude oil displacements.
Comprehensive Hydromechanical Specific Energy Calculation for Drilling Efficiency
Authors: Mohan Kshitij , Adil Faraaz , Samuel Robello
Published: August 2014

Over the last few years, different types of bits have been introduced to meet the challenges of steerable as well as rotary steerable systems; and it is imperative that bits be utilized optimally in these systems. As challenges increase with increasing depths, it becomes even more important for one to efficiently utilize the available energy (Robello, S., 2013, “Modeling and Analysis of Drillstring Vibration in Riserless Environment,” ASME J. Energy Res. Technol., 135(1), p. 013101). A new correlation identifying inefficient drilling conditions is presented in this paper. Mechanical specific energy (MSE) has been used to improve drilling rates, with mixed results. Hydro MSE (HMSE), which is introduced here, encompasses hydraulic as well as mechanical energy. HMSE quantifies the amount of energy required to drill a unit volume of rock and remove it from underneath the bit. HMSE includes axial, torsional, and hydraulic energy and is different from MSE because it includes a hydraulic term. The initial MSE correlation (Teale, R., 1965, “The Concept of Specific Energy in Rock Drilling,” Int. J. Rock Mech. Min. Sci., 2, pp. 57–73.) was modified to accommodate the new hydraulic term. This paper attempts to better model downhole drilling by introducing the hydraulic energy term in the MSE correlation by defining it as HMSE. While the majority of the drilling occurs because of the bit, it is a well-known fact that some drilling occurs due to the “jet impact impingement” caused by the drilling fluid as well. Experimental and field data presented in this paper show that HMSE can identify inefficient drilling conditions. The new hydraulic term included in the specific energy correlation is the key to correctly match the amount of energy required to drill and overcome the strength and stresses of formation being drilled. Also, this new term illustrates how much hydraulic energy is needed to drill faster when the mechanical energy (axial and torsional) is increased. The results also show the importance of including the bit hydraulic energy term into any specific energy analysis for drilling optimization. Field results reveal specific patterns for inefficient drilling conditions and also reveal a good correlation between calculated HMSE and the expected requirements for rock removal under existent conditions of stress at the bit face (Mohan, K., and Robello Samuel, F. A., 2009, “Tracking Drilling Efficiency Using Hydro-Mechanical Specific Energy,” SPE/IADC Drilling Conference and Exhibition, March 17–19, Amsterdam, The Netherlands, No. SPE 119421).
A Shape Parameterization Method Using Principal Component Analysis in Applications to Parametric Shape Optimization
Authors: Yonekura Kazuo , Watanabe Osamu
Published: August 2014

This paper proposes a shape parameterization method using a principal component analysis (PCA) for shape optimization. The proposed method is used as a preprocessing tool of parametric optimization algorithms, such as genetic algorithms (GAs) or response surface methods (RSMs). When these parametric optimization algorithms are used, the number of parameters should be small while the design space represented by the parameters should be able to represent a variety of shapes. In order to define the parameters, PCA is applied to shapes. In many industrial fields, a large amount of data of shapes and their performance is accumulated. By applying PCA to these shapes included in a database, important features of the shapes are extracted. A design space is defined by basis vectors which are generated from the extracted features. The number of dimensions of the design space is decreased without omitting important features. In this paper, each shape is discretized by a set of points and PCA is applied to it. A shape discretization method is also proposed and numerical examples are provided.
Modeling Aggregate Choice for Form and Function Through Metaconjoint Analysis
Authors: Sylcott Brian , Cagan Jonathan
Published: August 2014

In the previous work, meta-attributes have been used to model the relationship between two groups of disparate product attributes. There, preference for form, function, and the relationship between the two were modeled for individual consumers. However, this approach is limited as designers are often called on to choose a design that best appeals to a group of consumers, not individuals. This work expands on the concept and makes it more generally applicable by adapting metaconjoint to model aggregate choice for consumer groups. The results from this work show that a metaconjoint approach can be used to model aggregate choice for form and function and can yield better results on holdout sample predictions than form or function alone.
In-Plane Compliances of Planar Flexure Hinges With Serially Connected Straight- and Circular-Axis Segments
Authors: Lobontiu Nicolae
Published: August 2014

The paper introduces a new category of planar flexure hinges that are formed by serially connecting variable cross-sectional segments of straight longitudinal axes with segments of circular longitudinal axes. The small-displacement compliance analytical model is derived for a general hinge configuration using a matrix approach that sums the transformed local-frame compliance matrices of individual component segments. The particular class of antisymmetric flexure hinges is studied using the general model and the corresponding global-frame compliance matrix is calculated as a linear combination of compliances defining the half-hinge configuration. A serpentine (folded) flexure hinge is introduced to illustrate the generic antisymmetric design and model. Finite element simulation is used to validate the analytic compliances of this particular configuration and the compliance sensitivity to geometric parameters variation is further analyzed. The translation stiffnesses of a planar-motion stage with two identical serpentine hinges are calculated based on hinge compliances. The optimum hinge design is subsequently identified, which realizes minimum-resistance motion along the stage axial motion direction.
Mention and Focus Organism Detection and Their Applications for Scalable Systematic Bio-Ideation Tools
Authors: Vandevenne Dennis , Verhaegen Paul-Armand , Duflou R. Joost
Published: August 2014

More and more approaches for systematic biologically inspired design (BID) aim to scalably leverage large biological databases. To support the scalable systematic BID process, an automated method for mention and focus organism (FO) detection in biological strategy documents is proposed and validated to perform with 85% precision and 81% recall. Furthermore, a number of potential applications of mention and FO detection are presented, and the biodiversity of two corpora is measured.
Peak sound pressure and sound exposure level from underwater explosions in shallow water
Authors: Soloway Alexander G. , Dahl Peter H.
Published: August 2014

Experimental measurements of the peak pressure and sound exposure level (SEL) from underwater explosions collected 7 km off the coast of Virginia Beach, Virginia are presented. The peak pressures are compared to results from previous studies and a semi-empirical equation that is a function of measurement range and charge weight, and are found to be in good agreement. An empirical equation for SEL that similarly employs a scaling approach involving charge weight and range is also presented and shows promise for the prediction of SEL in shallow water.
Assessment and Monitoring of Ballistic and Maximal Upper-Body Strength Qualities in Athletes
Authors: Young Kieran P. , Haff G. Gregory , Newton Robert U. , Gabbett Tim J. , Sheppard Jeremy M.
Published: August 2014

Purpose:

To evaluate whether the dynamic strength index (DSI: ballistic peak force/isometric peak force) could be effectively used to guide specific training interventions and detect training-induced changes in maximal and ballistic strength.

Methods:

Twenty-four elite male athletes were assessed in the isometric bench press and a 45% 1-repetition-maximum (1RM) ballistic bench throw using a force plate and linear position transducer. The DSI was calculated using the peak force values obtained during the ballistic bench throw and isometric bench press. Athletes were then allocated into 2 groups as matched pairs based on their DSI and strength in the 1RM bench press. Over the 5 wk of training, athletes performed either high-load (80–100% 1RM) bench press or moderate-load (40–55% 1RM) ballistic bench throws.

Results:

The DSI was sensitive to disparate training methods, with the bench-press group increasing isometric bench-press peak force (P = .035, 91% likely), and the ballistic-bench-throw group increasing bench-throw peak force to a greater extent (P ≤ .001, 83% likely). A significant increase (P ≤ .001, 93% likely) in the DSI was observed for both groups.

Conclusions:

The DSI can be used to guide specific training interventions and can detect training-induced changes in isometric bench-press and ballistic bench-throw peak force over periods as short as 5 wk.
Effects of a Very Congested Match Schedule on Body-Load Impacts, Accelerations, and Running Measures in Youth Soccer Players
Authors: Arruda Ademir F.S. , Carling Christopher , Zanetti Vinicius , Aoki Marcelo S. , Coutts Aaron J. , Moreira Alexandre
Published: August 2014

Purpose:

To analyze the effects of a very congested match schedule on the total distance (TD) covered, high-intensity-running (HIR) distance, and frequency of accelerations and body-load impacts (BLIs) performed in a team of under-15 soccer players (N = 10; 15.1 ± 0.2 y, 171.8 ± 4.7 cm, 61 ± 6.0 kg) during an international youth competition.

Methods:

Using global positioning systems, player performances were repeatedly monitored in 5 matches performed over 3 successive days.

Results:

Significant differences were observed between matches (P < .05) for the frequency of accelerations per minute, BLIs, and BLIs per minute. No differences were observed for the TD covered, TD run per minute, number of high-intensity runs, distance covered in HIR, per-minute peak running speed attained, or frequency of accelerations. The frequency of accelerations per minute decreased across the competition while BLIs were higher during the final than in all other matches.

Conclusions:

These results suggest that BLIs and acceleration might be used as an alternative means to represent the external load during congested match schedules rather than measures related to running speed or distance covered.
Anthropometric and Physiological Profiling of Youth Soccer Goalkeepers
Authors: Rebelo-Gonçalves Ricardo , Coelho-e-Silva Manuel João , Severino Vítor , Tessitore Antonio , Figueiredo António José Barata
Published: August 2014

Studies focused on position-related characteristics of young soccer players often ignore the goalkeepers. The aim of this study was to examine the effect of playing position on anthropometry, physiological attributes, soccer skills, and goal orientation across adolescence. One hundred forty-five soccer players age 11–19 y were assessed in training experience, body size, maturation, physiological parameters, soccer skills, and goal orientation. Factorial ANOVA was used to test the effect of age group, playing position, and respective interaction terms, while analysis of variance was used to compare goalkeepers vs outfielders in middle (under 13 [U-13] and U-15) and late (U-17 and U-19) adolescence. Discriminant analysis was used to identify the variables that contributed to explaining playing positions. Age group was a consistent source of variation for all variables except task and ego orientations. Fat mass, agility, endurance, dribbling speed, shooting accuracy, and passing were affected by the gradient derived from the classification between goalkeepers and outfielders. It was possible to correctly classify the playing position based on fat-free mass and 3 manipulative skills in younger players and on 4 skills in U-17 and U-19 soccer players. Future research should include longitudinal information to improve our understanding of the factors that contribute to distinguish goalkeepers from outfielders.
Type IV collagen is an activating ligand for the adhesion G protein–coupled receptor GPR126
Authors: Paavola Kevin J. , Sidik Harwin , Zuchero J. Bradley , Eckart Michael , Talbot William S.
Published: August 2014

Type IV collagen activates the cell surface receptor GPR126, an orphan receptor that is crucial for Schwann cell differentiation and myelination.
Lipocalin 2 as a Membrane-Reorganizing Agent
Authors: Lingwood Daniel
Published: August 2014

A protein that binds to diverse hydrophobic substrates reorganizes the sperm plasma membrane in preparation for fertilization.
Bad Cholesterol: Bad for Bacteria, Too?
Authors: Mueller Kristen L.
Published: August 2014

Antiviral immune responses induce an oxysterol that suppresses interleukin-1–mediated inflammation.
How to Plumb the Root Is the Problem
Authors: Hines Pamela J.
Published: August 2014

A genetic network integrates hormonal inputs to establish a stable tissue pattern within a growing plant tissue.
Biofilm Positive Feedback
Authors: VanHook Annalisa M.
Published: August 2014

A two-component tyrosine kinase mediates positive feedback of exopolysaccharide production during biofilm formation.
Going a Notch More Beige
Authors: Wong Wei
Published: August 2014

The “browning” of white adipose tissue is induced upon suppression of Notch signaling.
Ascorbate Peroxidase, a Key Molecule Regulating Amphotericin B Resistance in Clinical Isolates of Leishmania donovani
Authors: Kumar Ashish , Das Sushmita , Purkait Bidyut , Sardar Abul Hasan , Ghosh Ayan Kumar , Dikhit Manas Ranjan , Abhishek Kumar , Das Pradeep
Published: August 2014

Amphotericin B (AmB), a polyene macrolide, is now a first-line treatment of visceral leishmaniasis cases refractory to antimonials in India. AmB relapse cases and the emergence of secondary resistance have now been reported. To understand the mechanism of AmB, differentially expressed genes in AmB resistance strains were identified by a DNA microarray and real-time reverse transcriptase PCR (RT-PCR) approach. Of the many genes functionally overexpressed in the presence of AmB, the ascorbate peroxidase gene from a resistant
Leishmania donovani
strain (LdAPx gene) was selected because the gene is present only in
Leishmania
, not in humans. Apoptosis-like cell death after exposure to AmB was investigated in a wild-type (WT) strain in which the LdAPx gene was overexpressed and in AmB-sensitive and -resistant strains. A higher percentage of apoptosis-like cell death after AmB treatment was noticed in the sensitive strain than in both the resistant isolate and the strain sensitive to LdAPx overexpression. This event is preceded by AmB-induced formation of reactive oxygen species and elevation of the cytosolic calcium level. Enhanced cytosolic calcium was found to be responsible for depolarization of the mitochondrial membrane potential and the release of cytochrome
c
(Cyt
c
) into the cytosol. The redox behavior of Cyt
c
showed that it has a role in the regulation of apoptosis-like cell death by activating metacaspase- and caspase-like proteins and causing concomitant nuclear alterations, as determined by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and DNA fragmentation in the resistant strain. The present study suggests that constitutive overexpression of LdAPx in the
L. donovani
AmB-resistant strain prevents cells from the deleterious effect of oxidative stress, i.e., mitochondrial dysfunction and cellular death induced by AmB.
Evolution of Oseltamivir Resistance Mutations in Influenza A(H1N1) and A(H3N2) Viruses during Selection in Experimentally Infected Mice
Authors: Pizzorno Andrés , Abed Yacine , Plante Pier-Luc , Carbonneau Julie , Baz Mariana , Hamelin Marie-Ève , Corbeil Jacques , Boivin Guy
Published: August 2014

The evolution of oseltamivir resistance mutations during selection through serial passages in animals is still poorly described. Herein, we assessed the evolution of neuraminidase (NA) and hemagglutinin (HA) genes of influenza A/WSN/33 (H1N1) and A/Victoria/3/75 (H3N2) viruses recovered from the lungs of experimentally infected BALB/c mice receiving suboptimal doses (0.05 and 1 mg/kg of body weight/day) of oseltamivir over two generations. The traditional phenotypic and genotypic methods as well as deep-sequencing analysis were used to characterize the potential selection of mutations and population dynamics of oseltamivir-resistant variants. No oseltamivir-resistant NA or HA changes were detected in the recovered A/WSN/33 viruses. However, we observed a positive selection of the I222T NA substitution in the recovered A/Victoria/3/75 viruses, with a frequency increasing over time and with an oseltamivir concentration from 4% in the initial pretherapy inoculum up to 28% after two lung passages. Although the presence of mixed I222T viral populations in mouse lungs only led to a minimal increase in oseltamivir 50% enzyme-inhibitory concentrations (IC50s) (by a mean of 5.7-fold) compared to that of the baseline virus, the expressed recombinant A/Victoria/3/75 I222T NA protein displayed a 16-fold increase in the oseltamivir IC50level compared to that of the recombinant wild type (WT). In conclusion, the combination of serialin vivopassages under neuraminidase inhibitor (NAI) pressure and temporal deep-sequencing analysis enabled, for the first time, the identification and selection of the oseltamivir-resistant I222T NA mutation in an influenza H3N2 virus. Additionalin vivoselection experiments with other antivirals and drug combinations might provide important information on the evolution of antiviral resistance in influenza viruses.
Pharmacokinetics ofpara-Aminosalicylic Acid in HIV-Uninfected and HIV-Coinfected Tuberculosis Patients Receiving Antiretroviral Therapy, Managed for Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis
Authors: de Kock Lizanne , Sy Sherwin K. B. , Rosenkranz Bernd , Diacon Andreas H. , Prescott Kim , Hernandez Kenneth R. , Yu Mingming , Derendorf Hartmut , Donald Peter R.
Published: August 2014

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR)Mycobacterium tuberculosisprompted the reintroduction ofpara-aminosalicylic acid (PAS) to protect companion anti-tuberculosis drugs from additional acquired resistance. In sub-Saharan Africa, MDR/XDR tuberculosis with HIV coinfection is common, and concurrent treatment of HIV infection and MDR/XDR tuberculosis is required. Out of necessity, patients receive multiple drugs, and PAS therapy is frequent; however, neither potential drug interactions nor the effects of HIV infection are known. Potential drug-drug interaction with PAS and the effect of HIV infection was examined in 73 pulmonary tuberculosis patients; 22 (30.1%) were HIV coinfected. Forty-one pulmonary MDR or XDR tuberculosis patients received 4 g PAS twice daily, and in a second crossover study, another 32 patients were randomized, receiving 4 g PAS twice daily or 8 g PAS once daily. A PAS population pharmacokinetic model in two dosing regimens was developed; potential covariates affecting its pharmacokinetics were examined, and Monte Carlo simulations were conducted evaluating the pharmacokinetic-pharmacodynamic index. The probability of target attainment (PTA) to maintain PAS levels above MIC during the dosing interval was estimated by simulation of once-, twice-, and thrice-daily dosing regimens not exceeding 12 g daily. Concurrent efavirenz (EFV) medication resulted in a 52% increase in PAS clearance and a corresponding >30% reduction in mean PAS area under the concentration curve in 19 of 22 HIV-M. tuberculosis-coinfected patients. Current practice recommends maintenance of PAS concentrations at ≥1 μg/ml (the MIC ofM. tuberculosis), but the model predicts that at only a minimum dose of 4 g twice daily can this PTA be achieved in at least 90% of the population, whether or not EFV is concomitantly administered. Once-daily dosing of 12 g PAS will not provide PAS concentrations exceeding the MIC over the entire dosing interval if coadministered with EFV, while 4 g twice daily ensures concentrations exceeding MIC over the entire dosing interval, even in HIV-infected patients who received EFV.
Chloroquine Has a Cytotoxic Effect on Acanthamoeba Encystation through Modulation of Autophagy
Authors: Jha Bijay Kumar , Jung Hui-Jung , Seo Incheol , Kim Hyun Ah , Suh Seong-Il , Suh Min-Ho , Baek Won-Ki
Published: August 2014

Encystation of
Acanthamoeba castellanii
is associated with resistance to chemotherapeutic agents. Blocking the encystation process could potentiate the efficacy of chemotherapeutic agents and biocides. During encystation, autophagy is highly stimulated and required for proper encystation of
Acanthamoeba
. In this study, the cytotoxic effect of chloroquine, a well-known autophagy-inhibitory drug, was tested in
A. castellanii
. Chloroquine was able to selectively reduce cell survival during the encystation of
A. castellanii
. However,
A. castellanii
trophozoites and mature cysts were resistant to chloroquine. Chloroquine treatment led to an increase in the number and size of lysosomes in encysting cells. Moreover, chloroquine inhibited the degradation of long-lived proteins in the encysting cells. Decreased autophagic flux, indicated by an increased number of lysosomes and decreased degradation of long-lived proteins, may be the mechanism by which cell death is induced by chloroquine in encysting
Acanthamoeba
. These results suggest a potential novel therapeutic application of chloroquine as an anti-
Acanthamoeba
drug. Our findings also suggest that targeting autophagy could be a therapeutic strategy against
Acanthamoeba
infection.
Comparison of the Antibiotic Activities of Daptomycin, Vancomycin, and the Investigational Fluoroquinolone Delafloxacin against Biofilms from Staphylococcus aureus Clinical Isolates
Authors: Siala Wafi , Mingeot-Leclercq Marie-Paule , Tulkens Paul M. , Hallin Marie , Denis Olivier , Van Bambeke Françoise
Published: August 2014

Biofilm-related infections remain a scourge. In an
in vitro
model of biofilms using
Staphylococcus aureus
reference strains, delafloxacin and daptomycin were found to be the most active among the antibiotics from 8 different pharmacological classes (J. Bauer, W. Siala, P. M. Tulkens, and F. Van Bambeke, Antimicrob. Agents Chemother. 57:2726–2737, 2013, doi:10.1128/AAC.00181-13). In this study, we compared delafloxacin to daptomycin and vancomycin using biofilms produced by 7 clinical strains (
S. aureus
epidemic clones CC5 and CC8) in order to rationalize the differences observed between the antibiotics and strains. The effects of the antibiotics on bacterial viability (resazurin reduction assay) and biomass (crystal violet staining) were measured and correlated with the proportion of polysaccharides in the matrix, the local microenvironmental pH (micro-pH), and the antibiotic penetration in the biofilm. At clinically meaningful concentrations, delafloxacin, daptomycin, and vancomycin caused a ≥25% reduction in viability against the biofilms formed by 5, 4, and 3 strains, respectively. The antibiotic penetration within the biofilms ranged from 0.6 to 52% for delafloxacin, 0.2 to 10% for daptomycin, and 0.2 to 1% for vancomycin; for delafloxacin, this was inversely related to the polysaccharide proportion in the matrix. Six biofilms were acidic, explaining the high potency of delafloxacin (lower MICs at acidic pH). Norspermidine and norspermine (disassembling the biofilm matrix) drastically increased delafloxacin potency and efficacy (50% reduction in viability for 6 biofilms at clinically meaningful concentrations) in direct correlation with its increased penetration within the biofilm, while they only modestly improved daptomycin efficacy (50% reduction in viability for 2 biofilms) and penetration, and they showed marginal effects with vancomycin. Delafloxacin potency and efficacy against biofilms are benefited by its penetration into the matrix and the local acidic micro-pH.
Identification of Acinetobacter baumannii Serum-Associated Antibiotic Efflux Pump Inhibitors
Authors: Blanchard Catlyn , Barnett Pamela , Perlmutter Jessamyn , Dunman Paul M.
Published: August 2014

Adaptive antibiotic resistance is a newly described phenomenon by which
Acinetobacter baumannii
induces efflux pump activity in response to host-associated environmental cues that may, in part, account for antibiotic treatment failures against clinically defined susceptible strains. To that end, during adaptation to growth in human serum, the organism induces approximately 22 putative efflux-associated genes and displays efflux-mediated minocycline tolerance at antibiotic concentrations corresponding to patient serum levels. Here, we show that in addition to minocycline, growth in human serum elicits
A. baumannii
efflux-mediated tolerance to the antibiotics ciprofloxacin, meropenem, tetracycline, and tigecycline. Moreover, using a whole-cell high-throughput screen and secondary assays, we identified novel serum-associated antibiotic efflux inhibitors that potentiated the activities of antibiotics toward serum-grown
A. baumannii
. Two compounds,

A

cinetobacter

b

aumannii
e
fflux
p
ump
i
nhibitor 1 (ABEPI1) [(
E
)-4-((4-chlorobenzylidene)amino)benezenesulfonamide] and ABEPI2 [
N
-tert-butyl-2-(1-tert-butyltetrazol-5-yl)sulfanylacetamide], were shown to lead to minocycline accumulation within
A. baumannii
during serum growth and inhibit the efflux potential of the organism. While both compounds also inhibited the antibiotic efflux properties of the bacterial pathogen
Pseudomonas aeruginosa
, they did not display significant cytotoxicity toward human cells or mammalian Ca
2+
channel inhibitory effects, suggesting that ABEPI1 and ABEPI2 represent promising structural scaffolds for the development of new classes of bacterial antibiotic efflux pump inhibitors that can be used to potentiate the activities of current and future antibiotics for the therapeutic intervention of Gram-negative bacterial infections.
Epithelial Innate Immune Response to Acinetobacter baumannii Challenge
Authors: Feng Zhimin , Jia Xun , Adams Mark D. , Ghosh Santosh K. , Bonomo Robert A. , Weinberg Aaron
Published: August 2014

Currently,
Acinetobacter baumannii
is recognized as one of the major pathogens seriously threatening our health care delivery system. Aspects of the innate immune response to
A. baumannii
infection are not yet well understood. Human β-defensins (hBDs) are epithelial cell-derived cationic antimicrobial peptides (AMPs) that also function to bridge the innate and adaptive immune system. We tested the induction of hBD-2 and -3 by
A. baumannii
on primary oral and skin epithelial cells and found that
A. baumannii
induces hBD-3 transcripts to a greater extent than it induces hBD-2 transcripts on both types of cells. In addition, we found that
A. baumannii
is susceptible to hBD-2 and -3 killing at submicromolar concentrations. Moreover, hBD-3 induction by
A. baumannii
was found to be dependent on epidermal growth factor receptor (EGFR) signaling. Inhibition of mitogen-activated protein kinase resulted in reduced expression of both hBD-2 and -3. Lastly, a disintegrin and metalloprotease 17 (ADAM17; also known as TACE) was found to be critical for hBD-3 induction, while ADAM10 and dual oxidase 1 (Duox1) were not required for hBD-3 induction. Induction of AMPs is an important component of innate sensing of pathogens and may play an important role in triggering systemic immune responses to
A. baumannii
infection. Further studies on the interactions between epithelial cells and
A. baumannii
will help us understand early stages of infection and may shed light on why some individuals are more vulnerable to
A. baumannii
infection.
Polymorphonuclear Leukocytes Restrict Growth of Pseudomonas aeruginosa in the Lungs of Cystic Fibrosis Patients
Authors: Kragh Kasper N. , Alhede Morten , Jensen Peter Ø. , Moser Claus , Scheike Thomas , Jacobsen Carsten S. , Seier Poulsen Steen , Eickhardt-Sørensen Steffen Robert , Trøstrup Hannah , Christoffersen Lars , Hougen Hans-Petter , Rickelt Lars F. , Kühl Michael , Høiby Niels , Bjarnsholt Thomas
Published: August 2014

Cystic fibrosis (CF) patients have increased susceptibility to chronic lung infections by
Pseudomonas aeruginosa
, but the ecophysiology within the CF lung during infections is poorly understood. The aim of this study was to elucidate the
in vivo
growth physiology of
P. aeruginosa
within lungs of chronically infected CF patients. A novel, quantitative peptide nucleic acid (PNA) fluorescence
in situ
hybridization (PNA-FISH)-based method was used to estimate the
in vivo
growth rates of
P. aeruginosa
directly in lung tissue samples from CF patients and the growth rates of
P. aeruginosa
in infected lungs in a mouse model. The growth rate of
P. aeruginosa
within CF lungs did not correlate with the dimensions of bacterial aggregates but showed an inverse correlation to the concentration of polymorphonuclear leukocytes (PMNs) surrounding the bacteria. A growth-limiting effect on
P. aeruginosa
by PMNs was also observed
in vitro
, where this limitation was alleviated in the presence of the alternative electron acceptor nitrate. The finding that
P. aeruginosa
growth patterns correlate with the number of surrounding PMNs points to a bacteriostatic effect by PMNs via their strong O
2
consumption, which slows the growth of
P. aeruginosa
in infected CF lungs. In support of this, the growth of
P. aeruginosa
was significantly higher in the respiratory airways than in the conducting airways of mice. These results indicate a complex host-pathogen interaction in chronic
P. aeruginosa
infection of the CF lung whereby PMNs slow the growth of the bacteria and render them less susceptible to antibiotic treatment while enabling them to persist by anaerobic respiration.
Human Monocyte Subsets at Homeostasis and Their Perturbation in Numbers and Function in Filarial Infection
Authors: Tolouei Semnani Roshanak , Moore Vanessa , Bennuru Sasisekhar , McDonald-Fleming Renee , Ganesan Sundar , Cotton Rachel , Anuradha Rajamanickam , Babu Subash , Nutman Thomas B.
Published: August 2014

To characterize the function and plasticity of the major human circulating monocyte populations and to explore their role in systemic helminth infection, highly purified (by flow-based sorting) human monocyte subsets (CD14hi/CD16neg[classical], CD14+ or hi/CD16med[intermediate], and CD14neg/CD16hi[nonclassical]) were examined at homeostasis and after activation. Among these three subsets the classical and intermediate subsets were found to be the major sources of inflammatory and regulatory cytokines, as well as cytokines/chemokines associated with alternative activation, whereas the nonclassical and classical populations demonstrated an ability to transmigrate through endothelial monolayers. Moreover, it was primarily the classical subset that was the most efficient in promoting autologous T cell proliferation. The distribution of these subsets changed in the context of a systemic helminth (Wuchereria bancrofti) infection such that patent infection altered the frequency and distribution of these monocyte subsets with the nonclassical monocytes being expanded (almost 2-fold) in filarial infection. To understand further the filarial/monocyte interface,in vitromodeling demonstrated that the classical subset internalized filarial antigens more efficiently than the other two subsets but that the parasite-driven regulatory cytokine interleukin-10 was exclusively coming from the intermediate subset. Our data suggest that monocyte subsets have a differential function at homeostasis and in response to helminth parasites.
New Insights into the Antimicrobial Effect of Mast Cells against Enterococcus faecalis
Authors: Scheb-Wetzel Matthias , Rohde Manfred , Bravo Alicia , Goldmann Oliver
Published: August 2014

Enterococcus faecalishas emerged as an important cause of life-threatening multidrug-resistant bacterial infections in the hospital setting. The pathogenesis of enterococcal infections has remained a relatively neglected field despite their obvious clinical relevance. The objective of this study was to characterize the interactions between mast cells (MCs), an innate immune cell population abundant in the intestinal lamina propria, andE. faecalis. This study was conducted with primary bone marrow-derived murine MCs. The results demonstrated that MCs exerted an antimicrobial effect againstE. faecalisthat was mediated both by degranulation, with the concomitant discharge of the antimicrobial effectors contained in the granules, and by the release of extracellular traps, in whichE. faecaliswas snared and killed. In particular, the cathelicidin LL-37 released by the MCs had potent antimicrobial effect againstE. faecalis. We also investigated the specific receptors involved in the recognition ofE. faecalisby MCs. We found that Toll-like receptors (TLRs) are critically involved in the MC recognition ofE. faecalis, since MCs deficient in the expression of MyD88, an adaptor molecule required for signaling by most TLRs, were significantly impaired in their capacity to degranulate, to reduceE. faecalisgrowth as well as to release tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) after encountering this pathogen. Furthermore, TLR2 was identified as the most prominent TLR involved in the recognition ofE. faecalisby MCs. The results of this study indicate that MCs may be important contributors to the host innate immune defenses againstE. faecalis.
Role of Pathogen-Derived Cell Wall Carbohydrates and Prostaglandin E
2
in Immune Response and Suppression of Fish Immunity by the Oomycete Saprolegnia parasitica
Authors: Belmonte Rodrigo , Wang Tiehui , Duncan Gary J. , Skaar Ida , Mélida Hugo , Bulone Vincent , van West Pieter , Secombes Christopher J.
Published: August 2014

Saprolegnia parasitica
is a freshwater oomycete that is capable of infecting several species of fin fish. Saprolegniosis, the disease caused by this microbe, has a substantial impact on Atlantic salmon aquaculture. No sustainable treatment against saprolegniosis is available, and little is known regarding the host response. In this study, we examined the immune response of Atlantic salmon to
S. parasitica
infection and to its cell wall carbohydrates.
Saprolegnia
triggers a strong inflammatory response in its host (i.e., induction of interleukin-1β
1
[IL-1β
1
], IL-6, and tumor necrosis factor alpha), while severely suppressing the expression of genes associated with adaptive immunity in fish, through downregulation of T-helper cell cytokines, antigen presentation machinery, and immunoglobulins. Oomycete cell wall carbohydrates were recognized by fish leukocytes, triggering upregulation of genes involved in the inflammatory response, similar to what is observed during infection. Our data suggest that
S. parasitica
is capable of producing prostaglanding E
2
(PGE
2
)
in vitro
, a metabolite not previously shown to be produced by oomycetes, and two proteins with homology to vertebrate enzymes known to play a role in prostaglandin biosynthesis have been identified in the oomycete genome. Exogenous PGE
2
was shown to increase the inflammatory response in fish leukocytes incubated with cell wall carbohydrates while suppressing genes involved in cellular immunity (gamma interferon [IFN-γ] and the IFN-γ-inducible protein [γ-IP]). Inhibition of
S. parasitica
zoospore germination and mycelial growth by two cyclooxygenase inhibitors (aspirin and indomethacin) also suggests that prostaglandins may be involved in oomycete development.
Functional and Structural Analysis of HicA3-HicB3, a Novel Toxin-Antitoxin System of Yersinia pestis
Authors: Bibi-Triki Sabrina , Li de la Sierra-Gallay Inès , Lazar Noureddine , Leroy Arnaud , Van Tilbeurgh Herman , Sebbane Florent , Pradel Elizabeth
Published: August 2014

The mechanisms involved in the virulence of
Yersinia pestis
, the plague pathogen, are not fully understood. In previous research, we found that a
Y. pestis
mutant lacking the HicB3 (YPO3369) putative orphan antitoxin was attenuated for virulence in a murine model of bubonic plague. Toxin-antitoxin systems (TASs) are widespread in prokaryotes. Most bacterial species possess many TASs of several types. In type II TASs, the toxin protein is bound and neutralized by its cognate antitoxin protein in the cytoplasm. Here we identify the
hicA3
gene encoding the toxin neutralized by HicB3 and show that HicA3-HicB3 constitutes a new functional type II TAS in
Y. pestis
. Using biochemical and mutagenesis-based approaches, we demonstrate that the HicA3 toxin is an RNase with a catalytic histidine residue. HicB3 has two functions: it sequesters and neutralizes HicA3 by blocking its active site, and it represses transcription of the
hicA3B3
operon. Gel shift assays and reporter fusion experiments indicate that the HicB3 antitoxin binds to two operators in the
hicA3B3
promoter region. We solved the X-ray structures of HicB3 and the HicA3-HicB3 complex; thus, we present the first crystal structure of a TA complex from the HicAB family. HicB3 forms a tetramer that can bind two HicA3 toxin molecules. HicA3 is monomeric and folds as a double-stranded-RNA-binding domain. The HicB3 N-terminal domain occludes the HicA3 active site, whereas its C-terminal domain folds as a ribbon-helix-helix DNA-binding motif.