bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental validation of Monte Carlo (MANTIS) simulated x‐ray response of columnar CsI scintillator screens
Authors: Freed Melanie , Miller Stuart , Tang Katherine , Badano Aldo 
Published: October 2009

Purpose:MANTIS is a Monte Carlo code developed for the detailed simulation of columnar CsI scintillator screens in x‐ray imaging systems. Validation of this code is needed to provide a reliable and valuable tool for system optimization and accurate reconstructions for a variety of x‐ray applications. Whereas previous validation efforts have focused on matching of summary statistics, in this work the authors examine the complete point response function (PRF) of the detector system in addition to relative light output values.Methods:Relative light output values and high‐resolution PRFs have been experimentally measured with a custom setup. A corresponding set of simulated light output values and PRFs have also been produced, where detailed knowledge of the experimental setup and CsI:Tl screen structures are accounted for in the simulations. Four different screens were investigated with different thicknesses, column tilt angles, and substrate types. A quantitative comparison between the experimental and simulated PRFs was performed for four different incidence angles (0°, 15°, 30°, and 45°) and two different x‐ray spectra (40 and 70 kVp). The figure of merit (FOM) used measures the normalized differences between the simulated and experimental data averaged over a region of interest.Results:Experimental relative light output values ranged from 1.456 to 1.650 and were in approximate agreement for aluminum substrates, but poor agreement for graphite substrates. The FOMs for all screen types, incidence angles, and energies ranged from 0.1929 to 0.4775. To put these FOMs in context, the same FOM was computed for 2D symmetric Gaussians fit to the same experimental data. These FOMs ranged from 0.2068 to 0.8029. Our analysis demonstrates that MANTIS reproduces experimental PRFs with higher accuracy than a symmetric 2D Gaussian fit to the experimental data in the majority of cases. Examination of the spatial distribution of differences between the PRFs shows that the main reason for errors between MANTIS and the experimental data is that MANTIS‐generated PRFs are sharper than the experimental PRFs.Conclusions:The experimental validation of MANTIS performed in this study demonstrates that MANTIS is able to reliably predict experimental PRFs, especially for thinner screens, and can reproduce the highly asymmetric shape seen in the experimental data. As a result, optimizations and reconstructions carried out using MANTIS should yield results indicative of actual detector performance. Better characterization of screen properties is necessary to reconcile the simulated light output values with experimental data.
Liquid crystal display response time estimation for medical applications
Authors: Elze Tobias , Tanner Thomas G. 
Published: October 2009

Purpose:Accurate characterization of diagnosis instruments is crucial in medical applications such as radiology and clinical neurosciences. While classical CRT medical displays have been replaced almost exclusively with liquid crystal devices (LCDs), the assessment of their temporal properties (response times) is still largely based on heuristic methods, which have not been evaluated thoroughly yet. The authors introduce a novel approach and show that it improves the accuracy and reliability compared to the common heuristic recommended by ISO 9241‐305 substantially for a wide range of settings.Methods:The approach is based on disentangling the signal from the modulatory backlight through division (division approach). They evaluated this method in two different ways: First, they applied both methods to luminance transition measurements of different LCD monitors. Second, they simulated LCD luminance transitions by modeling the LCD optical responses according to a physical liquid crystal director orientation model. The simulated data were generated for four different response times, each with four different backlight modulation frequencies. Both the novel and the ISO convolution method were applied to the data.Results:Application of the methods to the simulated data shows a bias of up to 46% for the ISO approach, while the novel division approach is biased at most 2%. In accordance with the simulations, estimates for real measurements show differences in the two approaches of more than 200% for some LCD panels.Conclusion:The division approach is robust against periodic backlight fluctuations and can reliably estimate even very short response times or small transitions. Unlike the established method, it meets the accuracy requirements of medical applications. In contrast, the popular convolution approach for estimating response times is prone to misestimations of time by several orders of magnitude and tend to further worsen as advances in LCD technology lead to shorter response times.
Dosimetric comparison of , , and radiocolloids in craniopharyngioma treatments
Authors: Sadeghi Mahdi , Karimi Elham , Hosseini S. Hamed 
Published: October 2009

Purpose:In the radionuclide treatment of some forms of brain tumors such as craniopharyngiomas, the selection of the appropriate radionuclide for therapy is a key element in treatment planning. The aim was to study the influence by considering the beta‐emitter radionuclide dose rate in an intracranial cyst.Methods:Dosimetry was performed using the MCNP4C radiation transport code. Analytical dosimetry was additionally performed using the Loevinger and the Berger formulas in the MATLAB software. Each result was compared under identical conditions. The advantages and disadvantages of using versus and were investigated.Results:The dose rate at the inner surface of the cyst wall was estimated to be for a concentration of . Under identical conditions of treatment, the corresponding dose rates were for and for . For a well‐defined cyst radius and identical wall thickness, higher dose rates resulted for .Conclusions:To achieve the same radiological burden, the required amount of physical activity of injectable solution is lower for. This is found to be a consequence of both the radionuclide physical half‐life and the pattern of energy deposition from the emitted radiation. According to the half‐life and dose‐rate results, would be a good substitute for .
Influence of Tigecycline on Expression of Virulence Factors in Biofilm-Associated Cells of Methicillin-Resistant
Staphylococcus aureus
Authors: Smith Karen , Gould Katherine A. , Ramage Gordon , Gemmell Curtis G. , Hinds Jason , Lang Sue 
Published: October 2009

ABSTRACT

Methicillin-resistant
Staphylococcus aureus
(MRSA) infections are complicated by the ability of the organism to grow in surface-adhered biofilms on a multitude of abiotic and biological surfaces. These multicellular communities are notoriously difficult to eradicate with antimicrobial therapy. Cells within the biofilm may be exposed to a sublethal concentration of the antimicrobial due to the metabolic and phenotypic diversity of the biofilm-associated cells or the protection offered by the biofilm structure. In the present study, the influence of a sublethal concentration of tigecycline on biofilms formed by an epidemic MRSA-16 isolate was investigated by transcriptome analysis. In the presence of the drug, 309 genes were upregulated and 213 genes were downregulated by more than twofold in comparison to the levels of gene regulation detected for the controls not grown in the presence of the drug. Microarray data were validated by real-time reverse transcription-PCR and phenotypic assays. Tigecycline altered the expression of a number of genes encoding proteins considered to be crucial for the virulence of
S. aureus
. These included the reduced expression of
icaC
, which is involved in polysaccharide intercellular adhesin production and biofilm development; the upregulation of
fnbA
,
clfB
, and
cna
, which encode adhesins which attach to human proteins; and the downregulation of the
cap
genes, which mediate the synthesis of the capsule polysaccharide. The expression of
tst
, which encodes toxic shock syndrome toxin 1 (TSST-1), was also significantly reduced; and an assay performed to quantify TSST-1 showed that the level of toxin production by cells treated with tigecycline decreased by 10-fold (
P
< 0.001) compared to the level of production by untreated control cells. This study suggests that tigecycline may reduce the expression of important virulence factors in
S. aureus
and supports further investigation to determine whether it could be a useful adjunct to therapy for the treatment of biofilm-mediated infections.
Φm46.1, the Main
Streptococcus pyogenes
Element Carrying
mef
(A) and
tet
(O) Genes
Authors: Brenciani Andrea , Bacciaglia Alessandro , Vignaroli Carla , Pugnaloni Armanda , Varaldo Pietro E. , Giovanetti Eleonora 
Published: October 2009

ABSTRACT

Φm46.1, the recognized representative of the most common variant of mobile, prophage-associated genetic elements carrying resistance genes
mef
(A) (which confers efflux-mediated erythromycin resistance) and
tet
(O) (which confers tetracycline resistance) in
Streptococcus pyogenes
, was fully characterized. Sequencing of the Φm46.1 genome (55,172 bp) demonstrated a modular organization typical of tailed bacteriophages. Electron microscopic analysis of mitomycin-induced Φm46.1 revealed phage particles with the distinctive icosahedral head and tail morphology of the
Siphoviridae
family. The chromosome integration site was within a 23S rRNA uracil methyltransferase gene. BLASTP analysis revealed that the proteins of Φm46.1 had high levels of amino acid sequence similarity to the amino acid sequences of proteins from other prophages, especially Φ10394.4 of
S. pyogenes
and λSa04 of
S. agalactiae
. Phage DNA was present in the host cell both as a prophage and as free circular DNA. The lysogeny module appears to have been split due to the insertion of a segment containing
tet
(O) (from integrated conjugative element 2096-RD.2) and
mef
(A) (from a Tn
1207.1
-like transposon) into the unintegrated phage DNA. The phage attachment sequence lies in the region between
tet
(O) and
mef
(A) in the unintegrated form. Thus, whereas in this form
tet
(O) is ∼5.5 kb upstream of
mef
(A), in the integrated form,
tet
(O), which lies close to the right end of the prophage, is ∼46.3 kb downstream of
mef
(A), which lies close to the left end of the prophage.
Klebsiella pneumoniae
AcrAB Efflux Pump Contributes to Antimicrobial Resistance and Virulence
Authors: Padilla Emma , Llobet Enrique , Doménech-Sánchez Antonio , Martínez-Martínez Luis , Bengoechea José Antonio , Albertí Sebastián 
Published: October 2009

ABSTRACT

Respiratory infections caused by
Klebsiella pneumoniae
are characterized by high rates of mortality and morbidity. Management of these infections is often difficult, due to the high frequency of strains that are resistant to multiple antimicrobial agents. Multidrug efflux pumps play a major role as a mechanism of antimicrobial resistance in Gram-negative pathogens. In the present study, we investigated the role of the
K. pneumoniae
AcrRAB operon in antimicrobial resistance and virulence by using isogenic knockouts deficient in the AcrB component and the AcrR repressor, both derived from the virulent strain 52145R. We demonstrated that the AcrB knockout was more susceptible, not only to quinolones, but also to other antimicrobial agents, including β-lactams, than the wild-type strain and the AcrR knockout. We further showed that the AcrB knockout was more susceptible to antimicrobial agents present in human bronchoalveolar lavage fluid and to human antimicrobial peptides than the wild-type strain and the AcrR knockout. Finally, the AcrB knockout exhibited a reduced capacity to cause pneumonia in a murine model, in contrast to the wild-type strain. The results of this study suggest that, in addition to contributing to the multidrug resistance phenotype, the AcrAB efflux pump may represent a novel virulence factor required for
K. pneumoniae
to resist innate immune defense mechanisms of the lung, thus facilitating the onset of pneumonia.
An Albumin-Conjugated Peptide Exhibits Potent Anti-HIV Activity and LongIn VivoHalf-Life
Authors: Xie Dong , Yao Cheng , Wang Li , Min Wenjie , Xu Jiahong , Xiao Jiahai , Huang Mingxian , Chen Bo , Liu Bin , Li Xiaolin , Jiang He 
Published: October 2009

ABSTRACTThe clinical application of conventional peptide drugs often is limited by their shortin vivohalf-life and potential immunogenicity. Frequent injection presents challenges to the treatment of chronic diseases, such as HIV infection. We chemically modified a peptide HIV fusion inhibitor with 3-maleimidopropionic acid (MPA), which allows rapid and irreversible conjugation with serum albumin at a 1:1 molar ratio. FB006M, with an MPA modification at the 13th amino acid, rapidly formed conjugate with albumin upon intravenous injection, and it exhibited a remarkably extendedin vivohalf-life. The albumin conjugate of FB006M displayed potent inhibitory activity against a number of laboratory and clinical isolates of HIV-1in vitroandin vivo. No immunogenicity or antibody formation was detected after repeated dosing. The clinical application of FB006M may decrease the cost of treatment and improve treatment compliance and patient quality of life.
Genetic Fusions of Heat-Labile (LT) and Heat-Stable (ST) Toxoids of Porcine EnterotoxigenicEscherichia coliElicit Neutralizing Anti-LT and Anti-STa antibodies
Authors: Zhang Weiping , Zhang Chengxian , Francis David H. , Fang Ying , Knudsen David , Nataro James P. , Robertson Donald C. 
Published: October 2009

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) strains are a major cause of diarrheal disease in humans and farm animals.E. colifimbriae, or colonization factor antigens (CFAs), and enterotoxins, including heat-labile enterotoxins (LT) and heat-stable enterotoxins (ST), are the key virulence factors in ETEC diarrhea. Unlike fimbriae or LT, STa has not often been included as an antigen in development of vaccines against ETEC diarrhea because of its poor immunogenicity. STa becomes immunogenic only after being coupled with a strongly immunogenic carrier protein. However, native or shorter STa antigens either had to retain toxic activity in order to become antigenic or elicited anti-STa antibodies that were not sufficiently protective. In this study, we genetically mutated the porcine LT (pLT) gene for a pLT192(R→G)toxoid and the porcine STa (pSTa) gene for three full-length pSTa toxoids [STa11(N→K), STa12(P→F), and STa13(A→Q)] and used the full-length pLT192as an adjuvant to carry the pSTa toxoid for pLT192:pSTa-toxoid fusion antigens. Rabbits immunized with pLT192:pSTa12or pLT192:pSTa13fusion protein developed high titers of anti-LT and anti-STa antibodies. Furthermore, rabbit antiserum and antifecal antibodies were able to neutralize purified cholera toxin (CT) and STa toxin. In addition, preliminary data suggested that suckling piglets born by a sow immunized with the pLT192:pSTa13fusion antigen were protected when challenged with an STa-positive ETEC strain. This study demonstrated that pSTa toxoids are antigenic when fused with a pLT toxoid and that the elicited anti-LT and anti-STa antibodies were protective. This fusion strategy could provide instructive information to develop effective toxoid vaccines against ETEC-associated diarrhea in animals and humans.
A Monoclonal Immunoglobulin G Antibody Directed against an Immunodominant Linear Epitope on the Ricin A Chain Confers Systemic and Mucosal Immunity to Ricin
Authors: Neal Lori M. , O'Hara Joanne , Brey Robert N. , Mantis Nicholas J. 
Published: October 2009

ABSTRACTDue to the potential use of ricin and other fast-acting toxins as agents of bioterrorism, there is an urgent need for the development of safe and effective antitoxin vaccines. A candidate ricin subunit vaccine (RiVax) consisting of a recombinant attenuated enzymatic A chain (RTA) has been shown to elicit protective antitoxin antibodies in mice and rabbits and is currently being tested in phase I human clinical trials. However, evaluation of the efficacy of this vaccine for humans is difficult for a number of reasons, including the fact that the key neutralizing B-cell epitopes on RTA have not been fully defined. Castelletti and colleagues (Clin. Exp. Immunol.136:365-372, 2004) recently identified a linear epitope on RTA, spanning residues L161 to I175, as a primary target of serum antibodies derived from humans who had been treated with ricin immunotoxin. While affinity-purified polyclonal IgG antibodies against this region of RTA were capable of neutralizing ricinin vitro, their capacity to confer protection against ricin challengein vivowas not determined. In this report, we describe the production and characterization of GD12, a murine monoclonal IgG1 antibody specifically directed against residues 163 to 174 (TLARSFIICIQM) of RTA. GD12 bound ricin holotoxin with high affinity (KD[dissociation constant], 2.9 × 10−9M) and neutralized it with a 50% inhibitory concentration of ∼0.25 μg/ml, as determined by a Vero cell-based cytotoxicity assay. Passive administration of GD12 was sufficient to protect BALB/c mice against intraperitoneal and intragastric ricin challenges. These data are important in terms of vaccine development, since they firmly establish that preexisting serum antibodies directed against residues 161 to 175 on RTA are sufficient to confer both systemic and mucosal immunity to ricin. The potential of GD12 to serve as a therapeutic following ricin challenge was not explored in this study.
Development of Immunoglobulin M Memory to Both a T-Cell-Independent and a T-Cell-Dependent Antigen following Infection withVibrio choleraeO1 in Bangladesh
Authors: Kendall Emily A. , Tarique Abdullah A. , Hossain Azim , Alam Mohammad Murshid , Arifuzzaman Mohammad , Akhtar Nayeema , Chowdhury Fahima , Khan Ashraful I. , LaRocque Regina C. , Harris Jason B. , Ryan Edward T. , Qadri Firdausi , Calderwood Stephen B. 
Published: October 2009

ABSTRACTVibrio choleraeO1 can cause severe watery diarrhea that can be life-threatening without treatment. Infection results in long-lasting protection against subsequent disease. Development of memory B cells of the immunoglobulin G (IgG) and IgA isotypes toV. choleraeO1 antigens, including serotype-specific lipopolysaccharide (LPS) and the B subunit of cholera toxin (CTB), after cholera infection has been demonstrated. Memory B cells of the IgM isotype may play a role in long-term protection, particularly against T-cell-independent antigens, but IgM memory has not been studied inV. choleraeO1 infection. Therefore, we assayed acute- and convalescent-phase blood samples from cholera patients for the presence of memory B cells that produce cholera antigen-specific IgM antibody upon polyclonal stimulation in in vitro culture. We also examined the development of serological and antibody-secreting cell responses following infection. Subjects developed significant IgM memory responses by day 30 after infection, both to the T-cell-independent antigen LPS and to the T-cell-dependent antigen CTB. No significant corresponding elevations in plasma IgM antibodies or circulating IgM antibody-secreting cells to CTB were detected. In 17 subjects followed to day 90 after infection, significant persistence of elevated IgM memory responses was not observed. The IgM memory response to CTB was negatively correlated with the IgG plasma antibody response to CTB, and there was a trend toward negative correlation between the IgM memory and IgA plasma antibody responses to LPS. We did not observe an association between the IgM memory response to LPS and the vibriocidal titer.
The effect of non-contingent and accurate performance feedback on pacing and time trial performance in 4-km track cycling
Authors: Mauger A R , Jones A M , Williams C A 
Published: October 2009

ObjectiveTo determine whether the provision of comparative performance feedback during 4 km track cycling affects completion time.DesignFive highly trained male cyclists first performed a baseline (BL) 4-km time trial (TT) on a velodrome track, followed by two further randomised 4-km TT, during which riders received either correct (COR) or non-contingent (FAL) feedback based on their BL performance.ResultsParticipants completed the COR TT in a significantly faster time (t4=−3.10, p<0.05) than the FAL TT (341 (8) s vs 350 (12) s). Over the TT, a significant difference in mean speed was apparent between the two conditions (F15,60=1.95, p<0.05) on the second (t4=4.71, p<0.05), 15th (t4=3.45, p<0.05) and final lap (t4=3.30, p<0.05).ConclusionThe significant difference in completion time and pacing strategy between the two conditions suggests that accurate, comparative performance feedback is beneficial to performance, especially during the start and end of an exercise bout. The results support the previously unfounded assumption that performance feedback is advantageous during exercise and highlights the importance of an athlete's support team during an event.
Setting standards for the prevention and management of travellers’ diarrhoea in elite athletes: an audit of one team during the Youth Commonwealth Games in India
Authors: Tillett E , Loosemore M 
Published: October 2009

Objective:Devise and implement evidence-based guidelines for the prevention and management of travellers’ diarrhoea (TD), and establish the incidence of TD during an elite sporting trip to India.Design:Literature review and audit.Setting:Youth Commonwealth Games in India 2008.Participants:All members of the Team England Squad.Main outcome measures:Hygiene guidelines included only drinking bottled water, eating hot food and regular hand washing with alcohol gel. Ciprofloxacin was offered to non-athlete team members as prophylaxis but not to athletes due to its possible association with tendon disease. Following implementation of these guidelines, the incidence of travellers’ diarrhoea (TD) in the whole squad was 24/122 (20%), compared with 7/14 (50%) on the reconnaissance trip (preguidelines). In those taking prophylactic ciprofloxacin, the incidence was 4/33 (12%), compared with 20/89 (23%) in those not taking ciprofloxacin. No athlete missed their event due to TD.Conclusions:The incidence of TD was less during the event than on the reconnaissance trip. The relative contribution to this reduction in strict hygiene guidelines as compared with potentially improved catering hygiene arrangements is unknown. Prophylactic ciprofloxacin also reduced the incidence of TD but it is probably not appropriate for use in elite athletes. Rifaximin may be an alternative for this group.