bluuebunny/crossref_metadata_2025 huggingface dataset:
Intention of future donations: a study of donors versus non‐donors
Authors: Martín‐Santana J. D. , Beerli‐Palacio A.
Published: December 2012

Background

Recent years have seen the level of blood donation at a world level come to a standstill or even decline. This situation requires blood donation services to make efforts to increase donor recruitment and retention, as well as to increase the frequency of donations among current donors. In order to obtain good results, it is essential to understand the factors that affect intention to donate.

Objectives

To determine the explanatory power of a set of factors on intention to donate blood, as well as evaluating the ability of current donors to motivate others.

Methods/Materials

A questionnaire was administered to a sample of 1015 Spanish individuals.

Results

Results indicate that (i) motivations and hindering factors have the greatest explanatory power on intention to donate, (ii) experience as a donor is the most explanatory factor on future intention and (iii) there are significant behavioural and sociodemographic differences between donors and non‐donors.

Conclusion

These findings suggest that it is necessary (i) to enhance the donor retention for maintaining the donation system using a personal and frequent communication with donors not only to remind them to schedule their next donation, but also to attract more donors; (ii) to recapture temporarily deferred donors, as they are less reluctant towards donation; (iii) to describe in detail how donation affects donors and clarify the importance of donation for society and (iv) to develop member get member programs in which current donors act as motivators amongst friends, coworkers and family.
The Magnaporthe oryzae effector AVR1–CO39 is translocated into rice cells independently of a fungal‐derived machinery
Authors: Ribot Cécile , Césari Stella , Abidi Imène , Chalvon Véronique , Bournaud Caroline , Vallet Julie , Lebrun Marc‐Henri , Morel Jean‐Benoit , Kroj Thomas
Published: December 2012

Effector proteins are key elements in plant–fungal interactions. The rice blast fungus Magnaporthe oryzae secretes numerous effectors that are suspected to be translocated inside plant cells. However, their cellular targets and the mechanisms of translocation are still unknown. Here, we have identified the open reading frame (ORF3) corresponding to the M. oryzae avirulence gene AVR1–CO39 that interacts with the rice resistance gene Pi–CO39 and encodes a small secreted protein without homology to other proteins. We demonstrate that AVR1–CO39 is specifically expressed and secreted at the plant–fungal interface during the biotrophic phase of infection. Live‐cell imaging with M. oryzae transformants expressing a translational fusion between AVR1–CO39 and the monomeric red fluorescent protein (mRFP) indicated that AVR1–CO39 is translocated into the cytoplasm of infected rice cells. Transient expression of an AVR1–CO39 isoform without a signal peptide in rice protoplasts triggers a Pi–CO39‐specific hypersensitive response, suggesting that recognition of AVR1–CO39 by the Pi–CO39 gene product occurs in the cytoplasm of rice cells. The native AVR1–CO39 protein enters the secretory pathway of rice protoplasts as demonstrated by the ER localization of AVR1–CO39:mRFP:HDEL translational fusions, and is correctly processed as shown by Western blotting. However, this secreted AVR1–CO39 isoform triggers a Pi–CO39‐specific hypersensitive response and accumulates inside rice protoplasts as shown by Western blotting and localization of AVR1–CO39:mRFP translational fusions. This indicates that AVR1–CO39 is secreted by rice protoplasts and re‐enters into the cytoplasm by unknown mechanisms, suggesting that translocation of AVR1–CO39 into rice cells occurs independently of fungal factors.
Global Imbalances and Petrodollars
Authors: Arezki Rabah , Hasanov Fuad
Published: December 2012

Oil exporters have run large current account surpluses. We explore oil exporters’ role in the global imbalances debate. Current account dynamics are estimated for oil‐exporting countries and the rest of the world. We find that fiscal policy has a much stronger effect on the current account of oil exporters than on current accounts of other countries. The current account adjustment of oil‐exporting countries is also faster. Fiscal policy of oil exporters can have a significant and speedy impact on global imbalances. The impact via the adjustment of exchange rates might not be effective.
On the Role of Imports in Enhancing Manufacturing Exports
Authors: Turco Alessia Lo , Maggioni Daniela
Published: December 2012

Making use of a large panel data set on Italian manufacturing firms, we provide evidence on the effect of imports on the firm's export performance. We distinguish imports of intermediates according to their origin, and we find that inputs sourced from low labour cost countries promote the firm's export activity. Imports from high‐income countries do not significantly contribute to the export orientation of firms, especially when both persistence in export and the possible endogeneity of the import measures are accounted for via system generalised method of moments (GMM) estimation of a linear probability model. Our evidence suggests that the impact of imports on the firms’ export activity works through the cost‐saving channel rather than the technology channel.
Offshoring of Tasks: Taylorism Versus Toyotism
Authors: Lanz Rainer , Miroudot Sébastien , Nordås Hildegunn K.
Published: December 2012

This paper contributes to the recent debate on trade in tasks, drawing on insights from the theory of the firm as well as recent developments in trade theory. Recent empirical literature suggests that between 20 and 30 per cent of all jobs in key OECD countries could be digitised and offshored. This study offers a cluster analysis which documents that offshorable and non‐offshorable tasks tend to be performed together across occupations. Therefore, when assessing the offshorability of a job, one needs to take into account all tasks being performed by the worker and the gains from fragmenting jobs versus the benefits of multi‐tasked workers (taylorism versus toyotism). Furthermore, one needs to distinguish between fragmentation of production and fragmentation of jobs.
Trade Policy Review for China: Continuing Globalisation Amidst the World Financial Crisis
Authors: Yao Shujie , Liu Change
Published: December 2012

The 2008 world financial crisis had led many industrialised countries to endure a significant decline in their GDPs. Though the Chinese government arranged a 4 trillion RMB stimulus package coupled with 30 trillion RMB of new bank credits in 2008–2010 to mitigate the impact of the world financial crisis, the growth of China’s international trade declined to a single‐digit level after 10 years of rapid growth at more than 20% per annum since its WTO accession. The latest WTO Trade Policy Review for China is a timely piece of literature which provides excellent information on China’s current economic situation, its trade and investment policies and government’s priorities of policy support. In this article, we intend to reveal the latest development in the Chinese economy from the second half of 2011 and to predict what it may happen in the next a couple of years. China’s determination to ‘go global’ has not faded and China can only become more open in the future.
Greece's Neoliberal Experiment and Working Class Resistance
Authors: Kretsos Lefteris
Published: December 2012

Greece has become an international point of reference and analysis due to its unfortunate pioneering role in the course of the current economic crisis. Since 2010, legal reforms linked to the “competitiveness” agenda set out in the main propagandists of neoliberal reforms (e.g., International Monetary Fund and Organization for Economic Cooperation and Development) have been promoted as a cure for the rising levels of public debt and deficit. The aim of this article is first to explore the competing views of the Greek labor market. As it is argued, Greece was not more heavily regulated than many other European Union member states, and labor law cannot in any sense be said to have caused the Greek sovereign debt crisis. Second, the analysis argues that deregulatory dynamics and welfare state retrenchment have turned unions and voters more radical, even if austerity policies are still winning. Such changes are driven by the meteoric rise of Syriza, and the decline of social democratic unionism in contrast to a stronger grassroots trade union movement with high mobilization and organizing capacities is another sign of the collapse of the old political order.
Investigating Some Technical Issues on Cohesive Zone Modeling of Fracture
Authors: Wang John T.
Published: December 2012

This study investigates some technical issues related to the use of cohesive zone models (CZMs) in modeling the fracture of materials with negligible plasticity outside the fracture process zone. These issues include: (1) why cohesive laws of different shapes can produce similar fracture predictions, (2) under what conditions CZM predictions have a high degree of agreement with linear elastic fracture mechanics (LEFM) analysis results, (3) when the shape of cohesive laws becomes important in the fracture predictions, and (4) why the opening profile along the cohesive zone length (CZL) needs to be accurately predicted. Two cohesive models were used in this study to address these technical issues. They are the linear softening cohesive model and the Dugdale perfectly plastic cohesive model. Each cohesive model uses five cohesive laws of different maximum tractions. All cohesive laws have the same cohesive work rate (CWR) defined by the area under the traction–separation curve. The effects of the maximum traction on the cohesive zone length and the critical remote applied stress are investigated for both models. The following conclusions from this study may provide some guidelines for the prediction of fracture using CZM. For a CZM to predict a fracture load similar to that obtained by an LEFM analysis, the cohesive zone length needs to be much smaller than the crack length, which reflects the small-scale yielding condition requirement for LEFM analysis to be valid. For large-scale cohesive zone cases, the predicted critical remote applied stresses depend on the shape of the cohesive models used and can significantly deviate from LEFM results. Furthermore, this study also reveals the importance of accurately predicting the cohesive zone profile for determining the critical remote applied load.
Analysis of Inverse Method Applied on Sandwich Probes
Authors: Berrich Emna , Aloui Fethi , Legrand Jack
Published: December 2012

Parallel plate disks (PPD) are often used for analyzing the effect of small amplitude oscillations with different frequencies. These devices allow the imposing of a well-known flow kinematics. Mass transfer problems and, particularly, convection-diffusion problems relating wall shear rate to mass transfer can thus be studied. Mass transfer signals can be determined from a sandwich electrodiffusion (ED) sensor frequency response. The experimental database constructed was used to check the inverse method. Indeed, the inverse method (Rehimi et al., 2006, “Inverse Method for Electrochemical Diagnostics of Flows,” Int. J. Heat Mass Transfer, 49, pp. 1242–1254) applied on a sandwich ED sensor was analyzed by comparing its instantaneous numerical wall shear rates to the known local and instantaneous experimental wall shear rate. Oscillatory flows amplitudes, frequencies effects, and flow direction effect have been studied in order to test the robustness of the inverse method to such effects. The little difference between experimental and numerical results is probably caused by the sensitivity of the sandwich sensor to such flow directions or to the neglecting of the insulating gap effect on the inverse method.
Specialized Algorithm for Navigation of a Micro Hopping Air Vehicle Using Only Inertial Sensors
Authors: Scheuermann Edward , Costello Mark
Published: December 2012

The need for accurate and reliable navigation techniques for micro air vehicles plays an important part in enabling autonomous operation. Traditional navigation systems typically rely on periodic global positioning system updates and provide little benefit when operating indoors or in other similarly shielded environments. Moreover, direct integration of the onboard inertial measurement unit data stream often results in substantial drift errors yielding virtually unusable positional information. This paper presents a new strategy for obtaining an accurate navigation solution for the special case of a micro hopping air vehicle, beginning from some known location and heading, using only one triaxial accelerometer and one triaxial gyroscope. Utilizing the unique dynamics of the hopping vehicle, a piece-wise navigation solution is constructed by selectively integrating the inertial data stream for only those short periods of time while the vehicle is airborne. Interhop data post processing and sensor bias recalibration are also used to further improve estimation accuracy. To assess the performance of the proposed algorithm, a series of tests were conducted in which the estimated vehicle position following a sequence of 10 consecutive hops was compared with measurements from an optical motion-capture system. On average, the final estimated vehicle position was within 0.70 m or just over 6% from its actual location based on a total traveled distance of approximately 11 m.
Study of Quantitative Numerical Prediction of Cavitation Erosion in Cavitating Flow
Authors: Ochiai Naoya , Iga Yuka , Nohmi Motohiko , Ikohagi Toshiaki
Published: December 2012

Cavitation erosion is a material damage phenomenon caused by the repeated application of impulsive pressure on a material surface induced by bubble collapse, and the establishment of a method by which to numerically predict cavitation erosion is desired. In the present study, a numerical quantitative prediction method of cavitation erosion in a cavitating flow is proposed. In the present method, a one-way coupled analysis of a cavitating flow field based on a gas-liquid two-phase Navier–Stokes equation (Eulerian) and bubbles in the cavitating flow by bubble dynamics (Lagrangian) is used to treat temporally and spatially different scale phenomena, such as the macroscopic phenomenon of a cavitating flow and the microscopic phenomenon of bubble collapse. Impulsive pressures acting on a material surface are evaluated based on the bubble collapse position, time, and intensity, and the erosion rate is quantitatively predicted using an existing material-dependent relationship between the impulsive energy (square of the impulsive force) and the maximum erosion rate. The erosion rate on a NACA0015 hydrofoil surface in an unsteady transient cavitating flow is predicted by the proposed method. The distribution of the predicted erosion rate corresponds qualitatively to the distribution of an experimental surface roughness increment of the same hydrofoil. Furthermore, the predicted erosion rate considering the bubble nuclei distribution is found to be of the same order of magnitude as the actual erosion rate, which indicates that considering bubble nuclei distribution is important for the prediction of cavitation erosion and that the present prediction method is valid to some degree.
Multicondition Optimization and Experimental Measurements of a Double-Blade Centrifugal Pump Impeller
Authors: Liu Houlin , Wang Kai , Yuan Shouqi , Tan Minggao , Wang Yong , Dong Liang
Published: December 2012

In order to improve internal unsteady flow in a double-blade centrifugal pump (DBCP), this study used major geometric parameters of the original design as the initial values, heads at three conditions (i.e., 80% design flow rate, 100% design flow rate, and 120% design flow rate) as the constraints conditions, and the maximum of weighted average efficiency at the three conditions as the objective function. An adaptive simulated annealing algorithm was selected to solve the energy performance calculation model and the supertransitive approximation method was applied to fix optimal weight factors of individual objectives. On the basis of hydraulic performance optimization, three-condition automatic computational fluid dynamics (CFD) optimization of impeller meridional plane for the DBCP was realized by means of Isight software integrated Pro/E, Gambit, and Fluent software. The shroud arc radii R0 and R1, shroud angle T1, hub arc radius R2, and hub angle T2 on the meridional plane were selected as the design variables and the maximum of weighted average hydraulic efficiency at the three conditions was chosen as the objective function. Performance characteristic test and particle image velocimetry (PIV) measurements of internal flow in the DBCP were conducted. Performance characteristic test results show that the weighted average efficiency of the impeller after the three-condition optimization has increased by 1.46% than that of original design. PIV measurements results show that vortex or recirculation phenomena in the impeller are distinctly improved under the three conditions.
Effect of oxygen plasma treatment on nonalloyed Al/Ti-based contact for high power InGaN/GaN vertical light-emitting diodes
Authors: Lim Wantae , Sung Youngkyu , Kim Sung-Joon , Shin Young-Chul , Jang Tae-Sung , Park Tae-Young , Kim Gi-Bum , Song Sang-Yeob , Lee Wan-Ho , Kim Yong-Il , Kim Sung-Tae , Pearton Stephen J.
Published: December 2012

InGaN/GaN vertical light emitting diodes (LEDs) with argon (Ar) and oxygen (O2) plasma-treated nonalloyed Al/Ti electrodes were fabricated on sapphire substrates. At the operating current of 350 mA, the forward voltage (VF) for O2 plasma-treated Al/Ti-based devices with dimensions 1360 × 1360 μm2 was improved, whose value was comparable or lower to that of nonalloyed Cr/Au-based devices. The Al/Ti electrodes resulted in improvement in optical output power of LEDs due to their high reflectivity (typically 10%–15% higher based on our data) compared to LEDs with conventional Cr/Au-based electrodes. The x-ray photoelectron spectroscopy showed the increase in Ga-O peak intensity during O2 plasma treatment. These results demonstrate that O2 plasma-treated Al/Ti electrodes reduced the contact resistance by forming a thin conductive GaOxN1−x layer at n-GaN surface.
Effect of buffer structures on AlGaN/GaN high electron mobility transistor reliability
Authors: Liu Lu , Lo Chien-Fong , Xi Yuyin , Ren Fan , Pearton Stephen J. , Laboutin Oleg , Cao Yu , Johnson J. Wayne , Kravchenko Ivan I.
Published: December 2012

AlGaN/GaN high electron mobility transistors (HEMTs) with three different types of buffer layers, including a GaN/AlGaN composite layer, or 1 or 2 μm GaN thick layers, were fabricated and their reliability compared. The HEMTs with the thick GaN buffer layer showed the lowest critical voltage (Vcri) during off-state drain step-stress, but this was increased by around 50% and 100% for devices with the composite AlGaN/GaN buffer layers or thinner GaN buffers, respectively. The Voff - state for HEMTs with thin GaN and composite buffers were ∼100 V, however, this degraded to 50–60 V for devices with thick GaN buffers due to the difference in peak electric field near the gate edge. A similar trend was observed in the isolation breakdown voltage measurements, with the highest Viso achieved based on thin GaN or composite buffer designs (600–700 V), while a much smaller Viso of ∼200 V was measured on HEMTs with the thick GaN buffer layers. These results demonstrate the strong influence of buffer structure and defect density on AlGaN/GaN HEMT performance and reliability.
Comparison of beam angle selection strategies for intracranial IMRT
Authors: Bangert Mark , Ziegenhein Peter , Oelfke Uwe
Published: December 2012

Purpose:

Various strategies to select beneficial beam ensembles for intensity‐modulated radiation therapy (IMRT) have been suggested over the years. These beam angle selection (BAS) strategies are usually evaluated against reference configurations applying equispaced coplanar beams but they are not compared to one another. Here, the authors present a meta analysis of four BAS strategies that incorporates fluence optimization (FO) into BAS by combinatorial optimization (CO) and one BAS strategy that decouples FO from BAS, i.e., spherical cluster analysis (SCA). The underlying parameters of the BAS process are investigated and the dosimetric benefits of the BAS strategies are quantified.

Methods:

For three intracranial lesions in proximity to organs at risk (OARs) the authors compare treatment plans applying equispaced coplanar beam ensembles with treatment plans using five different BAS strategies, i.e., four CO techniques and SCA, to establish coplanar and noncoplanar beam ensembles. Treatment plans applying 5, 7, 9, and 11 beams are investigated. For the CO strategies the authors perform BAS runs with a 5°, 10°, 15°, and 20° angular resolution, which corresponds to a minimum of 18 coplanar and a maximum of 1400 noncoplanar candidate beams. In total 272 treatment plans with different BAS settings are generated for every patient. The quality of the treatment plans is compared based on the protection of OARs yet integral dose, target homogeneity, and target conformity are also considered.

Results:

It is possible to reduce the average mean and maximum doses in OARs by more than 4 Gy (1 Gy) with optimized noncoplanar (coplanar) beam ensembles found with BAS by CO or SCA. For BAS including FO by CO, the individual algorithm used and the angular resolution in the space of candidate beams does not have a crucial impact on the quality of the resulting treatment plans. All CO algorithms yield similar target conformity and slightly improved target homogeneity in comparison to equispaced coplanar setups. Furthermore, optimized coplanar (noncoplanar) beam ensembles enabled more than a 6% (5%) reduction of the integral dose. For SCA, however, integral dose was increased and target conformity was decreased in comparison to equispaced coplanar setups—especially for a small number of beams.

Conclusion:

Both BAS strategies incorporating FO by CO and independent BAS strategies excluding FO provide dose savings in OARs for optimized coplanar and especially noncoplanar beam ensembles; they should not be neglected in the clinic.
Antimicrobial Susceptibility and Resistance Patterns among Helicobacter pylori Strains from The Gambia, West Africa
Authors: Secka Ousman , Berg Douglas E. , Antonio Martin , Corrah Tumani , Tapgun Mary , Walton Robert , Thomas Vivat , Galano Juan J. , Sancho Javier , Adegbola Richard A. , Thomas Julian E.
Published: December 2012

Helicobacter pylori
is a globally important and genetically diverse gastric pathogen that infects most people in developing countries. Eradication efforts are complicated by antibiotic resistance, which varies in frequency geographically. There are very few data on resistance in African strains. Sixty-four Gambian
H. pylori
strains were tested for antibiotic susceptibility. The role of
rdxA
in metronidazole (Mtz) susceptibility was tested by DNA transformation and sequencing; RdxA protein variants were interpreted in terms of RdxA structure. Forty-four strains (69%) were resistant to at least 8 μg of Mtz/ml. All six strains from infants, but only 24% of strains from adults, were sensitive (
P
= 0.0031). Representative Mtz-resistant (Mtz
r
) strains were rendered Mtz susceptible (Mtz
s
) by transformation with a functional
rdxA
gene; conversely, Mtz
s
strains were rendered Mtz
r
by
rdxA
inactivation. Many mutations were found by Gambian
H. pylori
rdxA
sequencing; mutations that probably inactivated
rdxA
in Mtz
r
strains were identified and explained using RdxA protein's structure. All of the strains were sensitive to clarithromycin and erythromycin. Amoxicillin and tetracycline resistance was rare. Sequence analysis indicated that most tetracycline resistance, when found, was not due to 16S rRNA gene mutations. These data suggest caution in the use of Mtz-based therapies in The Gambia. The increasing use of macrolides against respiratory infections in The Gambia calls for continued antibiotic susceptibility monitoring. The rich variety of
rdxA
mutations that we found will be useful in further structure-function studies of RdxA, the enzyme responsible for Mtz susceptibility in this important pathogen.
Pharmacokinetics, Safety, and Tolerability of GS-9851, a Nucleotide Analog Polymerase Inhibitor for Hepatitis C Virus, following Single Ascending Doses in Healthy Subjects
Authors: Denning Jill , Cornpropst Melanie , Flach Stephen D. , Berrey Michelle M. , Symonds William T.
Published: December 2012

To investigate the pharmacokinetics, safety, and tolerability of GS-9851 (formerly PSI-7851), a new nucleotide analog inhibitor of hepatitis C virus (HCV), we conducted a double-blind, parallel, placebo-controlled, randomized, single-ascending-dose study. Healthy subjects received oral doses of 25 to 800 mg GS-9851. Peak concentrations of GS-9851 in plasma were achieved more rapidly than those of the metabolites GS-566500 (formerly PSI-352707) and GS-331007 (formerly PSI-6206), with time to maximum concentration of drug in plasma (
t
max
) values of 1.0 to 1.8 h, 1.5 to 3.0 h, and 3.0 to 6.0 h, respectively. The majority of systemic drug exposure was from the nucleoside GS-331007, with maximum concentration of drug in plasma (
C
max
) and area under the concentration-time curve to the last measurable concentration (AUC

0–
t

) values at least 7- and 41-fold higher, respectively, than those obtained for GS-9851 after adjusting for differences in molecular weight. The terminal elimination half-life (
t
1/2
) of GS-331007 increased with the dose, achieving a
t
1/2
of 25.7 h at 800 mg GS-9851. Dose proportionality was not observed for GS-331007. The majority of drug recovered in urine was in the form of GS-331007, with the percentage of this metabolite in urine samples ranging from 57% to 27% with increasing dose. GS-9851 was generally well tolerated, with no maximum tolerated dose identified. In conclusion, GS-9851 and its metabolites demonstrated a favorable pharmacokinetic profile consistent with once-daily dosing, and therefore, further clinical studies evaluating GS-9851 in HCV-infected patients are warranted.
Pharmacokinetics, Pharmacodynamics, and Tolerability of GS-9851, a Nucleotide Analog Polymerase Inhibitor, following Multiple Ascending Doses in Patients with Chronic Hepatitis C Infection
Authors: Lawitz Eric , Rodriguez-Torres Maribel , Denning Jill M. , Albanis Efsevia , Cornpropst Melanie , Berrey Michelle M. , Symonds William T.
Published: December 2012

We conducted this double-blind, parallel-group, placebo-controlled, randomized, multiple-ascending-dose study to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of GS-9851 (formerly PSI-7851) in treatment-naïve patients infected with hepatitis C virus (HCV) genotype 1. Thirty-two patients received active doses up to 400 mg of GS-9851 once daily for 3 days. GS-9851 and the metabolite GS-566500 (formerly PSI-352707) were rapidly cleared from the plasma, with half-life (
t
1/2
) values of approximately 1 h for GS-9851 and 3 h for GS-566500. Accumulation (21%) was observed only for GS-331007 (formerly PSI-6206) after multiple dosing. GS-331007 was the primary drug-related moiety in the plasma and urine. Increases in the GS-9851, GS-566500, and GS-331007 maximum concentrations in plasma (
C
max
) and area under the concentration-time curve (AUC) were less than dose proportional, particularly at the highest doses. The decline in plasma HCV RNA levels was dose dependent, and a mean maximal change from the baseline of −1.95 log
10
IU/ml was obtained for 400 mg GS-9851, compared with −0.090 log
10
IU/ml for the placebo. Most patients had a decrease in HCV RNA of ≥1.0 log
10
IU/ml after 3 days' dosing with 400 mg GS-9851. No virologic resistance was observed. GS-9851 was generally well tolerated, with no notable differences in adverse event frequency across doses. The pharmacokinetic profile observed in this study was similar to that seen in a single-ascending-dose study in healthy subjects.
Multiscale Distribution and Bioaccumulation Analysis of Clofazimine Reveals a Massive Immune System-Mediated Xenobiotic Sequestration Response
Authors: Baik Jason , Stringer Kathleen A. , Mane Gerta , Rosania Gus R.
Published: December 2012

Chronic exposure to some well-absorbed but slowly eliminated xenobiotics can lead to their bioaccumulation in living organisms. Here, we studied the bioaccumulation and distribution of clofazimine, a riminophenazine antibiotic used to treat mycobacterial infection. Using mice as a model organism, we performed a multiscale, quantitative analysis to reveal the sites of clofazimine bioaccumulation during chronic, long-term exposure. Remarkably, between 3 and 8 weeks of dietary administration, clofazimine massively redistributed from adipose tissue to liver and spleen. During this time, clofazimine concentration in fat and serum significantly decreased, while the mass of clofazimine in spleen and liver increased by >10-fold. These changes were paralleled by the accumulation of clofazimine in the resident macrophages of the lymphatic organs, with as much as 90% of the clofazimine mass in spleen sequestered in intracellular crystal-like drug inclusions (CLDIs). The amount of clofazimine associated with CLDIs of liver and spleen macrophages disproportionately increased and ultimately accounted for a major fraction of the total clofazimine in the host. After treatment was discontinued, clofazimine was retained in spleen while its concentrations decreased in blood and other organs. Immunologically, clofazimine bioaccumulation induced a local, monocyte-specific upregulation of various chemokines and receptors. However, interleukin-1 receptor antagonist was also upregulated, and the acute-phase response pathways and oxidant capacity decreased or remained unchanged, marking a concomitant activation of an anti-inflammatory response. These experiments indicate an inducible, immune system-dependent, xenobiotic sequestration response affecting the atypical pharmacokinetics of a small molecule chemotherapeutic agent.
In Vitro
Interaction between Alginate Lyase and Amphotericin B against Aspergillus fumigatus Biofilm Determined by Different Methods
Authors: Bugli Francesca , Posteraro Brunella , Papi Massimiliano , Torelli Riccardo , Maiorana Alessandro , Paroni Sterbini Francesco , Posteraro Patrizia , Sanguinetti Maurizio , De Spirito Marco
Published: December 2012

Aspergillus fumigatus
biofilms represent a problematic clinical entity, especially because of their recalcitrance to antifungal drugs, which poses a number of therapeutic implications for invasive aspergillosis, the most difficult-to-treat
Aspergillus
-related disease. While the antibiofilm activities of amphotericin B (AMB) deoxycholate and its lipid formulations (e.g., liposomal AMB [LAMB]) are well documented, the effectiveness of these drugs in combination with nonantifungal agents is poorly understood. In the present study,
in vitro
interactions between polyene antifungals (AMB and LAMB) and alginate lyase (AlgL), an enzyme degrading the polysaccharides produced as extracellular polymeric substances (EPSs) within the biofilm matrix, against
A. fumigatus
biofilms were evaluated by using the checkerboard microdilution and the time-kill assays. Furthermore, atomic force microscopy (AFM) was used to image and quantify the effects of AlgL-antifungal combinations on biofilm-growing hyphal cells. On the basis of fractional inhibitory concentration index values, synergy was found between both AMB formulations and AlgL, and this finding was also confirmed by the time-kill test. Finally, AFM analysis showed that when
A. fumigatus
biofilms were treated with AlgL or polyene alone, as well as with their combination, both a reduction of hyphal thicknesses and an increase of adhesive forces were observed compared to the findings for untreated controls, probably owing to the different action by the enzyme or the antifungal compounds. Interestingly, marked physical changes were noticed in
A. fumigatus
biofilms exposed to the AlgL-antifungal combinations compared with the physical characteristics detected after exposure to the antifungals alone, indicating that AlgL may enhance the antibiofilm activity of both AMB and LAMB, perhaps by disrupting the hypha-embedding EPSs and thus facilitating the drugs to reach biofilm cells. Taken together, our results suggest that a combination of AlgL and a polyene antifungal may prove to be a new therapeutic strategy for invasive aspergillosis, while reinforcing the EPS as a valuable antibiofilm drug target.
Apoptotic Marker Expression in the Absence of Cell Death in Staurosporine-Treated Leishmania donovani
Authors: Foucher Aude L. , Rachidi Najma , Gharbi Sarah , Blisnick Thierry , Bastin Philippe , Pemberton Iain K. , Späth Gerald F.
Published: December 2012

The protozoan parasite
Leishmania donovani
undergoes several developmental transitions in its insect and vertebrate hosts that are induced by environmental changes. The roles of protein kinases in these adaptive differentiation steps and their potential as targets for antiparasitic intervention are only poorly characterized. Here, we used the generic protein kinase inhibitor staurosporine to gain insight into how interference with phosphotransferase activities affects the viability, growth, and motility of
L. donovani
promastigotes
in vitro
. Unlike the nonkinase drugs miltefosine and amphotericin B, staurosporine strongly reduced parasite biosynthetic activity and had a cytostatic rather than a cytotoxic effect. Despite the induction of a number of classical apoptotic markers, including caspase-like activity and surface binding of annexin V, we determined that, on the basis of cellular integrity, staurosporine did not cause cell death but caused cell cycle arrest and abrogated parasite motility. In contrast, targeted inhibition of the parasite casein kinase 1 (CK1) protein family by use of the CK1-specific inhibitor D4476 resulted in cell death. Thus, pleiotropic inhibition of
L. donovani
protein kinases and possibly other ATP-binding proteins by staurosporine dissociates apoptotic marker expression from cell death, which underscores the relevance of specific rather than broad kinase inhibitors for antiparasitic drug development.
In Vivo
Therapeutic Efficacy of Chloroquine Alone or in Combination with Primaquine against Vivax Malaria in Kolkata, West Bengal, India, and Polymorphism in
pvmdr1
and
pvcrt-o
Genes
Authors: Ganguly Swagata , Saha Pabitra , Guha Subhasish K. , Das Sonali , Bera Dilip K. , Biswas Asit , Kundu Pratip K. , Saha Bibhuti , Ray Krishnangshu , Maji Ardhendu K.
Published: December 2012

Plasmodium vivax
malaria, though benign, has now become a matter of concern due to recent reports of life-threatening severity and development of parasite resistance to different antimalarial drugs. The magnitude of the problem is still undetermined. The present study was undertaken to determine the
in vivo
efficacy of chloroquine (CQ) and chloroquine plus primaquine in
P. vivax
malaria in Kolkata and polymorphisms in the
pvmdr1
and
pvcrt-o
genes. A total of 250 patients with
P. vivax
monoinfection were recruited and randomized into two groups, A and B; treated with chloroquine and chloroquine plus primaquine, respectively; and followed up for 42 days according to the WHO protocol of 2009. Data were analyzed using per-protocol analyses. We assessed polymorphisms of the
pvmdr1 and pvcrt-o
genes by a DNA-sequencing method. Out of the 250 patients recruited, 204 completed a 42-day follow-up period, 101 in group A and 103 in group B. In group A, the non-PCR-corrected efficacy of CQ was 99% (95% confidence interval [CI], 0.944 to 1.00), and in group B, all cases were classified as adequate clinical and parasitological response (ACPR). Day 3 positivity was observed in 11 (5.3%) cases. No specific mutation pattern was recorded in the
pvcrt-o
gene. Eight nonsynonymous mutations were found in the
pvmdr1
gene, three of which were new. The Y976F mutation was not detected in any isolate. Chloroquine, either alone or in combination with primaquine, is still effective against
P. vivax
malaria in the study area. (The study protocol was registered in CTRI [Clinical Trial Registry-India] of the Indian council of Medical Research under registration no. CTRI/2011/09/002031.)
Fosfomycin Synergy
In Vitro
with Amoxicillin, Daptomycin, and Linezolid against Vancomycin-Resistant Enterococcus faecium from Renal Transplant Patients with Infected Urinary Stents
Authors: Descourouez Jillian L. , Jorgenson Margaret R. , Wergin Justine E. , Rose Warren E.
Published: December 2012

Fosfomycin is a potential option for vancomycin-resistant enterococcus (VRE) infections despite limited
in vitro
and clinical data. In this study, 32 VRE isolates from renal transplant patients with urinary stent infections were susceptible to fosfomycin, daptomycin, and linezolid and resistant to amoxicillin, minocycline, and nitrofurantoin based on their MIC
50
s and MIC
90
s. Fosfomycin was bacteriostatic at 0.5 to 16× the MIC (32 to 2,048 μg/ml); synergy occurred when fosfomycin was combined with daptomycin (2.8 to 3.9 log
10
CFU/ml kill;
P
< 0.001) or amoxicillin (2.6 to 3.4;
P
< 0.05). These combinations may be potent options to treat VRE urinary infections pending investigation of clinical efficacy.
Outcomes of Appropriate Empiric Combination versus Monotherapy for Pseudomonas aeruginosa Bacteremia
Authors: Bowers Dana R. , Liew Yi-Xin , Lye David C. , Kwa Andrea L. , Hsu Li-Yang , Tam Vincent H.
Published: December 2012

Pseudomonas aeruginosa
bacteremia is associated with high hospital mortality. Empirical combination therapy is commonly used to increase the likelihood of appropriate therapy, but the benefits of employing >1 active agent have yet to be established. The purpose of this study was to compare outcomes of patients receiving appropriate empirical combination versus monotherapy for
P. aeruginosa
bacteremia. This was a retrospective, multicenter, cohort study of hospitalized adult patients with
P. aeruginosa
bacteremia from 2002 to 2011. The primary endpoint (30-day mortality) was assessed using multivariate logistic regression, adjusting for underlying confounding variables. Secondary endpoints of hospital mortality and time to mortality were assessed by Fisher's exact test and the Cox proportional hazards model, respectively. A total of 384 patients were analyzed. Thirty-day mortality was higher for patients receiving inappropriate therapy than for those receiving appropriate empirical therapy (43.8% versus 21.5%;
P
= 0.03). However, there were no statistical differences in 30-day mortality following appropriate empirical combination versus monotherapy after adjusting for baseline APACHE II scores and lengths of hospital stay prior to the onset of bacteremia (
P
= 0.55). Observed hospital mortality was 36.6% for patients administered combination therapy, compared with 28.7% for monotherapy patients (
P
= 0.17). After adjusting for baseline APACHE II scores, the relationship between time to mortality and combination therapy was not statistically significant (
P
= 0.59). Overall, no significant differences were observed for 30-day mortality, hospital mortality, and time to mortality between combination and monotherapy for
P. aeruginosa
bacteremia. Empirical combination therapy did not appear to offer an additional benefit, as long as the isolate was susceptible to at least one antimicrobial agent.
Evidence for Broad-Spectrum Biofilm Inhibition by the Bacterium Bacillus sp. Strain SW9
Authors: Wu Zhuoying , Ye Chengsong , Guo Feng , Zhang Shenghua , Yu Xin
Published: December 2012

We isolated a
Bacillus
sp. strain that could display broad-spectrum biofilm inhibition. The broad biofilm prevention could be achieved mainly by direct contact between inhibitor and target cells or was accompanied by an interaction with secreted inhibitory compounds. The repression of cell surface fimbria-like appendages of a biofilm producer was also observed; this was considered to contribute to the reduction in mixed biofilms.
Sanitizer Efficacy against Murine Norovirus, a Surrogate for Human Norovirus, on Stainless Steel Surfaces when Using Three Application Methods
Authors: Bolton Stephanie L. , Kotwal Grishma , Harrison Mark A. , Law S. Edward , Harrison Judy A. , Cannon Jennifer L.
Published: December 2012

Human noroviruses are major etiologic agents of epidemic gastroenteritis. Outbreaks are often accompanied by contamination of environmental surfaces, but since these viruses cannot be routinely propagated in laboratory cultures, their response to surface disinfectants is predicted by using surrogates, such as murine norovirus 1 (MNV-1). This study compared the virucidal efficacies of various liquid treatments (three sanitizer liquids, 5% levulinic acid plus 2% SDS [LEV/SDS], 200 ppm chlorine, and an isopropanol-based quaternary ammonium compound [Alpet D2], and two control liquids, sterile tap water and sterile tap water plus 2% SDS) when delivered to MNV-1-inoculated stainless steel surfaces by conventional hydraulic or air-assisted, induction-charged (AAIC) electrostatic spraying or by wiping with impregnated towelettes. For the spray treatments, LEV/SDS proved effective when applied with hydraulic and AAIC electrostatic spraying, providing virus reductions of 2.71 and 1.66 log PFU/ml, respectively. Alpet D2 provided a 2.23-log PFU/ml reduction with hydraulic spraying, outperforming chlorine (1.16-log PFU/ml reduction). Chlorine and LEV/SDS were equally effective as wipes, reducing the viral load by 7.05 log PFU/ml. Controls reduced the viral load by <1 log with spraying applications and by >3 log PFU/ml with wiping. Results indicated that both sanitizer type and application methods should be carefully considered when choosing a surface disinfectant to best prevent and control environmental contamination by noroviruses.
Nutrient Environments Influence Competition among Aspergillus flavus Genotypes
Authors: Mehl Hillary L. , Cotty Peter J.
Published: December 2012

The population dynamics of
Aspergillus flavus
, shaped in part by intraspecific competition, influence the likelihood and severity of crop aflatoxin contamination. Competition for nutrients may be one factor modulating intraspecific interactions, but the influences of specific types and concentrations of nutrients on competition between genotypes of
A. flavus
have not been investigated. Competition between paired
A. flavus
isolates on agar media was affected by varying concentrations of carbon (sucrose or asparagine) and nitrogen (nitrate or asparagine). Cocultivated isolate percentages from conidia and agar-embedded mycelia were quantified by measurements of isolate-specific single-nucleotide polymorphisms with quantitative pyrosequencing. Compositions and concentrations of nutrients influenced conidiation resulting from cocultivation, but the percentages of total conidia from each competing isolate were not predicted by sporulation of isolates grown individually. Success during sporulation did not reflect the outcomes of competition during mycelial growth, and the extents to which isolate percentages from conidia and mycelia differed varied among both isolate pairs and media. Whether varying concentrations of sucrose, nitrate, or asparagine increased, decreased, or had no influence on competitive ability was isolate dependent. Different responses of
A. flavus
isolates to nutrient variability suggest genotypes are adapted to different nutrient environments that have the potential to influence
A. flavus
population structure and the epidemiology of aflatoxin contamination.
Identification of One Novel Candidate Probiotic Lactobacillus plantarum Strain Active against Influenza Virus Infection in Mice by a Large-Scale Screening
Authors: Kechaou Noura , Chain Florian , Gratadoux Jean-Jacques , Blugeon Sébastien , Bertho Nicolas , Chevalier Christophe , Le Goffic Ronan , Courau Stéphanie , Molimard Pascal , Chatel Jean Marc , Langella Philippe , Bermúdez-Humarán Luis G.
Published: December 2012

In this study, we developed a large-scale screening of bacterial strains in order to identify novel candidate probiotics with immunomodulatory properties. For this, 158 strains, including a majority of lactic acid bacteria (LAB), were screened by two different cellular models: tumor necrosis factor alpha (TNF-α)-activated HT-29 cells and peripheral blood mononuclear cells (PBMCs). Different strains responsive to both models (pro- and anti-inflammatory strains) were selected, and their protective effects were tested
in vivo
in a murine model of influenza virus infection. Daily intragastric administrations during 10 days before and 10 days after viral challenge (100 PFU of influenza virus H1N1 strain A Puerto Rico/8/1934 [A/PR8/34]/mouse) of
Lactobacillus plantarum
CNRZ1997, one potentially proinflammatory probiotic strain, led to a significant improvement in mouse health by reducing weight loss, alleviating clinical symptoms, and inhibiting significantly virus proliferation in lungs. In conclusion, in this study, we have combined two cellular models to allow the screening of a large number of LAB for their immunomodulatory properties. Moreover, we identified a novel candidate probiotic strain,
L. plantarum
CNRZ1997, active against influenza virus infection in mice.
Integration of Vibrio vulnificus into Marine Aggregates and Its Subsequent Uptake by Crassostrea virginica Oysters
Authors: Froelich Brett , Ayrapetyan Mesrop , Oliver James D.
Published: December 2012

Marine aggregates are naturally forming conglomerations of larvacean houses, phytoplankton, microbes, and inorganics adhered together by exocellular polymers. In this study, we show
in vitro
that the bacterial pathogen
Vibrio vulnificus
can be concentrated into laboratory-generated aggregates from surrounding water. We further show that environmental (E-genotype) strains exhibit significantly more integration into these aggregates than clinical (C-genotype) strains. Experiments where marine aggregates with attached
V. vulnificus
cells were fed to oysters (
Crassostrea virginica
) resulted in greater uptake of both C and E types than nonaggregated controls. When C- and E-genotype strains were cocultured in competitive experiments, the aggregated E-genotype strains exhibited significantly greater uptake by oyster than the C-genotype strains.
Engineering the Substrate Specificity of a Thermophilic Penicillin Acylase from Thermus thermophilus
Authors: Torres Leticia L. , Cantero Ángel , del Valle Mercedes , Marina Anabel , López-Gallego Fernando , Guisán José M. , Berenguer José , Hidalgo Aurelio
Published: December 2012

A homologue of the
Escherichia coli
penicillin acylase is encoded in the genomes of several thermophiles, including in different
Thermus thermophilus
strains. Although the natural substrate of this enzyme is not known, this acylase shows a marked preference for penicillin K over penicillin G. Three-dimensional models were created in which the catalytic residues and the substrate binding pocket were identified. Through rational redesign, residues were replaced to mimic the aromatic binding site of the
E. coli
penicillin G acylase. A set of enzyme variants containing between one and four amino acid replacements was generated, with altered catalytic properties in the hydrolyses of penicillins K and G. The introduction of a single phenylalanine residue in position α188, α189, or β24 improved the

K
m

for penicillin G between 9- and 12-fold, and the catalytic efficiency of these variants for penicillin G was improved up to 6.6-fold. Structural models, as well as docking analyses, can predict the positioning of penicillins G and K for catalysis and can demonstrate how binding in a productive pose is compromised when more than one bulky phenylalanine residue is introduced into the active site.