bluuebunny/crossref_metadata_2025 huggingface dataset:
TH‐C‐BRB‐11: Range‐Guided Proton Prostate Treatment by Anterior Fields
Authors: Tang S , Bentefour H , Gottschalk B , Casio E , Prieels D , Lu H
Published: November 2011

Purpose: Only bi‐lateral fields are used for proton prostate treatment in current practice, often giving less favorable dose conformity and organ sparing than IMRT. Prostate treatment by anterior fields can utilize the sharp distal fall‐off of the Bragg peaks to spare the rectum, but this will require an accurate pre‐treatment “range check” for every fraction. We have developed and validated a range‐guided proton therapy (RGPT) technique for such treatments. Methods: Our technique utilizes the fact that in treatment by passively scattered beams, the time‐resolved dose rate signal at a point in patients encodes the corresponding water‐equivalent pathlenght (WEPL). A characteristic relationship between the r.m.s widths of signals and the corresponding WEPLs is calibrated and validated in a water tank. By measuring the signals at critical points with in‐vivo dosimeters, the WEPLs to these points can be obtained. An anthropomorphic pelvic phantom with a rectal cavity and water‐filled bladder was used in the study. Anterior treatment fields were planned using the CMS/XiO planning system. A detector array (6×3 cm) consisting of 16 diodes was placed directly below the anterior rectal wall supported by an endorectal water balloon. A range‐ check beam of 18 cm was first used, with the treatment hardware (aperture and compensator) in place, to verify the WEPLs to the detectors and hence the beam range for treatment. Finally the treatment beam with the corrected range was used to deliver the prescribed dose. Results: The differences in WEPLs between the measured and those calculated by the planning system were <2 mm at points behind the prostate target volume. The dose used for the range verification was <1 cGy. Potential improvements in data acquisition and analysis could achieve millimeter accuracy. Conclusions: Our study indicates that the RGPT technique is simple, effective and reliable for prostate treatment by anterior fields.
TH‐C‐BRB‐12: Fundamental Technical Performance Acceptance Testing Results of a Commercial High Definition Discrete Pencil Beam Scanning System
Authors: Farr J , Dessy F , Schoenenberg D , Claereboudt Y , Bietzer O , De Wilde O
Published: November 2011

Purpose: This study reports on the basic physics acceptance testing results of a pre‐clinical proton discrete pencil beam scanning (PBS) system (sometimes also known as modulated scanning). Methods: The PBS system tested consists of a 230 MeV cyclotron, a continuous range selector and a dedicated scanning nozzle mounted on two instances of a rotational gantry. The following basic field/beam qualities of the system were determined: maximum field size, lateral and longitudinal field uniformity of a one liter cubic uniform field, output stability over time, gantry angle invariance, monitoring system linearity and reproducibility. Ionization chambers, film and scintillation dosimetry were used. A test scan pattern was irradiated to determine beam in air transverse properties. Results: A 10 × 10 × 10 cm test field was shown to be homogeneous within +/− 3% laterally and longitudinally at high and low energy taking about 2–3 minutes to deliver an approximate physical dose of 2 Gy. The machine output showed variation of 1 % over one month and 1 % dependency over 5 tested gantry angles. Pencil beam alignment to gantry iso‐center was better than 1 mm. The irradiated test pattern analysis indicated that the delivered fluence map when Gaussian blurred for the measured spot profile agreed within 1.5%/1.5mm gamma factor to the physical measurement. The delivery system resolution exceeded the highest test pattern resolution bars that had been spaced at two line pairs per cm. Conclusions: The results suggest that the pre‐clinical PBS system delivers homogeneous fluence under nominal test conditions and gives high performance with respect to accuracy, precision and resolution. A higher resolution test pattern is called for in order to determine the intrinsic PBS resolution.
TH‐C‐BRC‐04: Hierarchical Real‐Time Respiratory Motion Prediction: A Divide‐and‐Conquer Scheme for Application‐Oriented Optimality
Authors: Ruan D
Published: November 2011

Purpose: Motion management applications differ in their measurement rates and prediction length requirement: it is unlikely to find a Universityersally optimal predictor. This study develops a divide‐and‐conquer scheme, by partitioning the operation region and assigning proper predictor to each sub‐ region. Such hierarchical fusion architecture achieves application‐dependent optimal prediction performance. Method and Materials: We parameterize the overall operation region of real‐time prediction in terms of (measurement rate, prediction length) to parameterize the configuration and requirement of various motion management systems. The region of study is set to be [5Hz, 30Hz]*[200ms,600ms], spanning the full scope from non‐ tomographic to tomographic measurement, and for both gating and tracking controls. Four predictor candidates are examined: (a) adaptive linear (b) interactive multiple linear (MLM) (c) KDE (d) local circular motion (LCM); and it is determined that LCM is optimal for low measurement rates and short prediction lengths, while KDE is superior for medium‐to‐high measurement rate and medium‐to‐long prediction length. An operation‐ region specific hybrid model is developed and compared with the individual predictors. Prediction performance is quantified by nRMSE between predicted value and retrospective observations. Normalization with data deviation ensures meaningful population‐based statistics. Results: The proposed method outperforms all individual benchmark methods uniformly. The nRMSE was controlled to be under 0.15 for 200ms prediction and 0.4 for 600ms prediction, translating to sub‐mm prediction accuracy for typical respiratory motions. Conclusion: We have developed a hybrid predictor that adapts to specific motion management applications. This hybrid predictor combines the simplicity of the LCM model under low data rate condition, and the flexibility of the nonparametric KDE approach for long prediction lengths. The general methodology of divide‐and‐conquer extend to incorporate other predictors naturally, should they offer better performance in a sub‐region. The resulting hierarchical predictor uniformly outperforms individual methods, and provides an ideal motion management module for motion‐adaptive radiotherapy.
TH‐C‐BRC‐05: 4DCBCT Reconstruction Using a PCA Based DVF Motion Model
Authors: Staub D , Docef A , Murphy M
Published: November 2011

Purpose: To develop a 4D cone beam CT (4DCBCT) reconstruction algorithm that produces a time series of images with high spatial and temporal resolution, minimal artifact, and no time averaging of data as compared to standard 4DCBCT reconstruction techniques. Methods: Our algorithm works to constrain a motion model by using it to deform a static prior CT image at multiple time steps. It then adjusts the motion model parameters until digitally reconstructed radiographs (DRRs) taken through the deformed prior optimally match the projections of the raw 4DCBCT data‐set. Once the motion model parameters have been optimized the motion model can be used to animate the static CT, in essence producing a 3D video that serves as the reconstructed 4DCBCT. Our motion model uses principal components analysis (PCA) of a DVF training set to generate eigenvectors characterizing de‐correlated modes of anatomic motion. It produces new DVFs by computing weighted sums of the eigenvectors. Each eigenvector weight, or principal coefficient, varies in time uniquely according to a parameterized version of the patient breathing trace. Results: Our current focus is on proof of concept testing using numerically generated data. We plan to test the algorithm on simulated data with different degrees of motion complexity. In addition, we will test the effect on eigenvector quality of different DVF training set acquisition methods. Early results indicate that when supplied with an ideal DVF training set the model can reproduce simple motion to a high degree of accuracy. Conclusions: Our current task is to test our algorithmˈs reconstruction quality with numerically simulated data of varying complexity. Beyond that we plan to test on phantom and patient data. If our reconstruction algorithm is successful it will produce 4DCBCTs with high spatial and temporal resolution, low artifact, and no time averaging.

This work supported by NIH P01 CA116602.
TH‐C‐BRC‐06: Performance Measures and Pre‐Processing for Respiratory Motion Prediction
Authors: Ernst F , Bruder R , Schlaefer A , Schweikard A
Published: November 2011

Purpose: Much research has been done on prediction of respiratory motion traces for motion compensation in radiotherapy. Unfortunately, the results of different groups cannot be compared easily due to different standards in preprocessing and analysis of the results. Furthermore, it has been speculated that the typically used measure for prediction quality, the RMS error, is not sufficient alone. Methods: We propose a set of guidelines for signal preprocessing (i.e., for scaling, detrending, resampling, and denoising) as well as measures for the analysis of the prediction results. The latter complement the RMS error with confidence intervals, the signalˈs smoothness (called jitter) and a measure for the periodicity of the error (called frequency content). Additionally, we have developed an extendable cross‐platform prediction toolkit for easy analysis of prediction algorithms. Results: We found that very different signals (corrupted by noise, scaled by a constant factor, delayed in time, and scaled by random factors for each respiratory period) feature the exact same RMS error when compared to the original signal. The fundamental difference in the error signals can only be determined when using spectral measures, like the frequency content. Conclusion: Using the guidelines developed, the proposed evaluation measures, as well as the publicly available prediction toolkit, should help the community in establishing a better understanding for the capabilities and shortcomings of individual prediction methods. Additionally, it should allow others to more readily compare newly developed methods to already published algorithms. In the future, it would be desirable to also create a database of motion traces from various sources. If these signals would represent the characteristics of motion traces observed in the clinic, it could serve as a general benchmark for the quality of algorithms for motion prediction.
TH‐C‐BRC‐09: Tracking Moving Tumors with a Scanned Carbon Beam: Robustness to Changing Target Motion Characteristics and Tracking Uncertainties
Authors: Eley J , Lüchtenborg R , Richter D , Durante M , Bert C
Published: November 2011

Purpose: Beam tracking of moving tumors with scanned carbon ion radiotherapy achieves uniform target dose by adapting carbon pencil beams to follow moving tissues using real‐time lateral magnetic deflection and range modulation. The purpose of the current study was to establish the robustness of target dose coverage that can be achieved in the presence of changing target motion characteristics and uncertainties in the motion tracking system. Methods: A 4D research treatment planning system code for ion therapy was extended to compute the resulting target dose coverage when various random and systematic uncertainties were introduced to ideal tracking dose simulations. Treatment plans were prepared using the in‐ house code for a hypothetical sphere target volume with sinusoidal motion in a water phantom. Uncertainties were simulated by shifting pencil beam coordinates and modifying target motion signals. To simulate imperfect tracking, we considered variations to the following: (1) respiratory period, (2) starting respiratory phase, (3) target position drift, (4) random tracking offsets, (5) range tracking wedge acceleration, and (6) external respiratory motion signal phase delay. We also considered imperfect tracking with combinations of varying target motion characteristics and tracking uncertainties. A total of 13713 dose distributions were computed. For all cases, mean, standard deviation, minimum, and maximum of target dose were analyzed. Results: For perfect tracking of the moving sphere, mean and standard deviation of target dose were 98.2 and 0.8 % of the prescription dose, respectively. Of the variations considered, systematic drifts of target position of up to 5 mm had the most significant effect on target coverage ((6.6 ± 20.3) % decrease), and range tracking wedge accelerations above 1.0 g had the least effect on target dose ((0.0 ±1.1) %). Conclusions: The results provide insight into beam tracking precision requirements and the need to monitor and mitigate changes in patient motion.

Work supported by research grant from the Deutscher Akademischer Austausch Dienst, Bonn, Germany.
TH‐C‐214‐02: MRI for Radiation Treatment Planning
Authors: Cao Y
Published: November 2011

The advantages of MRI for radiation treatment planning, such as soft tissue discrimination and multi‐contrast capability, are well recognized. It is routine practice to use MRI for tumor target definition of brain tumors, with or without a corresponding CT scan. Superior soft tissue visualization has led to the emergence of MRI‐guided brachytherapy for cervical and prostate cancers. In addition, functional and physiological MR imaging can aid assessment of tumor and normal tissue response for adaptive RT as well as pre‐treatment boost target definition. Several past limitations of MRI have hindered its wide application in radiation therapy, including concerns about geometric accuracy, high resolution volumetric acquisition, acquisition speed, motion‐sensitivity, small bore size, and lack of definition of bony structures and electron density. Many of these shortcomings have been overcome or will be overcome by new MRI technologies.

This lecture will provide an overview on new MRI technologies and their application for radiation treatment planning. The limitations of these techniques will also be discussed.

Learning objectives:

1. Understand new MRI technologies that are relevant to radiation treatment planning;

2. Understand the influence of imaging parameters on image quality and contrast.

3. Understand clinical applications and limitations.
TH‐C‐214‐04: This House Believes That the Use of Functional Imaging for Treatment Planning of Head and Neck Tumors Needs to Be Carefully Considered
Authors: Gregoire V , Geets X , Lee J
Published: November 2011

Biological image‐guided radiotherapy aims at specifically irradiating biologically relevant sub‐volumes within the tumor, as determined for instance by PET imaging. This approach requires that PET imaging be sensitive and specific enough to image various biological pathways of interest, e.g. tumor metabolism, proliferation and hypoxia. In this framework, the use of PET imaging for adaptive radiotherapy needs to be evaluated in term of accuracy and added value in comparison with standard procedures.

It first requires the optimization of the PET image quality during the acquisition and the reconstruction, to try to improve the spatial resolution, the level of noise and the contrast, that are typical features of PET imaging. Thereafter, it requires robust and validated tools for accurate segmentation of the regions of interest. The blur effect related to the poor spatial resolution of the camera and the high level of noise severely corrupt the images, and consequently interfere with the tumor segmentation. The use of “image restoration tools” for deblurring and denoising PET images before any segmentation represents an elegant way to improve image quality. Associated with a gradient‐based segmentation technique, this approach has been shown to outperform the conventional threshold‐based methods. However, even when using optimal procedures for image acquisition, reconstruction and segmentation, one has to keep in mind that there will always exist some discrepancies between the information from a PET image and the underlying microscopic reality. Such differences may be of critical importance when considering giving boost doses to small and highly active PET regions. This issue should be carefully looked at before applying on a clinical routine basis sub‐volume segmentation with some form of dose‐ painting. Last outcome studies should be ideally performed as an ultimate endpoint to ascertain the clinical benefit of the use of functional imaging in routine practice.
TH‐C‐110‐01: Current and Future Clinical Applications of Quantitative CT
Authors: Boone J
Published: November 2011

Computed tomography (CT) is the only current clinical modality which is fundamentally quantitative. While other modalities can in many cases be calibrated to deliver a linear response, the normalization with respect to water of the Hounsfield Unit is the standard in clinical CT imaging. Furthermore, gray scale in CT is linearly related to the concentration of injected iodine contrast agent, which is useful for CT‐based organ function assessment. In addition to a quantitative gray scale, CT is a robust quantitative tool in regards to distances in three dimensions. Because of the straight‐line assumption used in x‐ray imaging including CT, in the absence of patient motion, distances, areas, and volumes can in principle be measured with accuracy. Modern multi‐slice CT scanners allow thin section imaging, and thus the volume data sets produce near‐isotropic spatial resolution. These properties of CT have led to a number of quantitative applications: CT has been used to quantify bone mineral density for almost 30 years, and this tool has proven useful in quantitative risk assessment in patients with osteoporosis. Researchers in pulmonary function have used CT to measure changes in the lung parenchyma over time. Organ perfusion measurements are commonly performed in the head for the evaluation in patients suspected of stroke or vasospasm, and abdominal organ perfusion measurements have also been studied in cancer patients. Computed tomography remains a primary tool for the assessment of tumor size, in monitoring the response to chemotherapy in cancer patients. While linear dimension assessment is a RECIST criterion, there has been a recent move towards tumor volume assessment to better capture tumor response. After a brief review of the fundamental properties of CT pertinent to its quantitative performance, a number of clinically used quantitative CT applications will be discussed. Issues of accuracy and precision will also be addressed. A discussion of the expansion of CT as a quantitative tool in other clinical applications will conclude this presentation.

Learning Objectives:

1. The physical basis for quantitative CT will be described

2. Current applications of quantitative CT will be outlined

3. The precision and accuracy of volume and HU metrics will be described

4. A list of potential future applications in quantitative CT will be presented.
TH‐C‐301‐05: Practical Medical Physics Session
Authors: Lewis D
Published: November 2011

Among dosimetry tools radiographic films have the unique advantage of providing the capability for dose measurements at very high spatial resolution; and between dosimetry films, radiochromic films are particularly advantageous for their versatility. Thus radiochromic films can be handled in light, easily cut to any size and shape, bent to conform to curved surfaces and immersed in water. All these attributes are embodied in the GAFCHROMIC® family of dosimetry films as used in a broad spectrum of medical applications including external beam therapy, brachytherapy, machine quality assurance and radiology.

Current trends in external beam therapy are towards ever more precise treatment protocols with less dose fractionation. Both these factors increase the importance of pre‐treatment validation of treatment plans and place a high and increasing value on those measurement techniques that are able to deliver the ability for excellent resolution in the spatial frequency and dose domains.

The talk will show, by example, the range of medical applications covered by radiochromic dosimetry films. It will demonstrate how the attributes of these films are being used to advantage in a full spectrum of radiotherapy applications. The presentation will finish by introducing another advantage of radiochromic film and showing the benefit of multi‐channel film dosimetry as a means for improving the integrity of dose measurements by separating dose‐independent artifacts and removing them from the response measurement.
TH‐C‐220‐12: Biochemical Radiation Response of Irradiated Human Tumour Cells Observed via Raman Spectroscopy
Authors: Matthews Q , Jirasek A , Brolo A , Lum J
Published: November 2011

Purpose: To use non‐invasive single‐cell Raman spectroscopy (RS) and principal component analysis (PCA) to analyze radiation‐induced biochemical changes in human tumour cell lines, and to correlate results with known radiosensitivity. Methods: Six human tumour cell lines, derived from prostate (DU145, PC3, and LNCaP), breast (MDA‐MB‐231 and MCF7) and lung (H460), were irradiated with single fractions (15, 30 or 50 Gy) of 6 MV photons. Remaining live cells were harvested for RS analysis at 0, 24, 48, and 72 hours post‐irradiation, along with unirradiated controls. Single‐cell Raman spectra were acquired from 20 cells per sample with a Raman microscope utilizing a 785 nm excitation laser. All spectra (200 per cell line) were post‐processed, and the total data set for each cell line was analyzed with PCA using standard algorithms. Results: One unique radiation‐induced PCA component was detected for each cell line by identification of statistically significant changes in the PCA score distributions for irradiated samples, as compared to unirradiated samples, in the first 24 to 72 hours post‐irradiation. Correlation analysis between radiation‐induced PCA components from the different cell lines shows that these RS radiation response signatures fall into 3 distinct RS categories: R1 (H460 and MCF7), R2 (MDA‐MB‐231 and PC3), and R3 (DU145 and LNCaP). These RS categories segregate according to radiosensitivity and p53 gene status. The R1 and R2 cell lines are radioresistant (SF2 > 0.6), whereas the R3 cell lines are radiosensitive (SF2 < 0.5). The R1 and R2 cell lines further segregate according to p53 status, as verified by cell cycle analysis post‐irradiation. Conclusions: This study demonstrates that RS is a powerful tool for non‐invasive radiobiological investigations, and is a promising technique for advancing the field of personalized radiation therapy.
TH‐E‐BRB‐01: Significant Improvement of Plan Quality, Delivery Efficiency and Plan Consistency by VMAT Combined with Automated Inverse Planning Algorithm for Stereotactic Body Radiation Therapy in Centrally/superiorly Located Stage I Non‐Small‐Cell Lung Cancer
Authors: Li X , Chang J , Liu W , Quan E , Balter P , Zhang X
Published: November 2011

Purpose: SBRT has been reported to result in excellent local control in stage I non‐small‐cell lung cancer (NSCLC) using 3D‐CRT. However, toxicity could be significant for lesions located centrally/superiorly and the delivery time for each fraction takes about 35–40 minutes. In order to minimize the normal tissue dose and the risk of the intra‐fractional motion, VMAT plans generated by our in‐house developed automated inverse planning (AIP) method are studied and compared to 3D‐CRT plans for SBRT to treat NSCLC. Methods and materials: Treatment plans for 11 patients with central or superior stage I NSCLC treated by 3D‐CRT SBRT were selected for this study. The central/superior tumors are those located within 2cm from the bronchial tree, esophagus, heart, major vessels, trachea or brachial plexus but 1cm away from the spinal cord. All the patients underwent 4D CT simulation, and daily CT‐on‐rail guided CT. The AIP algorithm was implemented as a plug‐in of Pinnacle (9.100) and therefore all the plans generated were deliverable plans which could be directly employed to treat patients. The prescribed dose was 50 Gy in 4 fractions to the target volume. Iso‐dose line distributions and dose volume histograms for both plans were compared also. Maximum tolerable dose (MTD) was defined as the preset critical‐structure dose‐volume constraints. Results: With the similar target coverage, the clinical plans for only 7 patients satisfied all the MTD constrains, whereas the AIP‐generated VMAT plans did for all the patients. The VMAT plans remarkably reduced the dose to nearly all the critical structures and resulted in approximately 37% more monitor units but could be delivered with 8 minutes. Conclusion: Compared to 3D‐CRT, VMAT with AIP method for SBRT has superior plan quality, excellent delivery efficiency and exceptional plan consistency. It is the preferred modality to treat the patients with NSCLC located centrally/superiorly.
Science Signaling
Podcast: 8 November 2011
Authors: Sabatini David M. , VanHook Annalisa M.
Published: November 2011

The vacuolar ATPase is required for amino acid–mediated activation of mTORC1.
Exercise for Life
Authors: Hurtley Stella M.
Published: November 2011

Gentle exercise can ameliorate disease severity in a mouse model of a fatal neurodegenerative disease.
Downregulation of Mitogen-Activated Protein Kinase 1 of Leishmania donovani Field Isolates Is Associated with Antimony Resistance
Authors: Ashutosh  , Garg Mansi , Sundar Shyam , Duncan Robert , Nakhasi Hira L. , Goyal Neena
Published: November 2011

Emergence of resistance to pentavalent antimonials has become a severe obstacle in the treatment of visceral leishmaniasis (VL) on the Indian subcontinent. The mechanisms operating in laboratory-generated strains are somewhat known, but the determinants of clinical antimony resistance are not well understood. By utilizing a DNA microarray expression profiling approach, we identified a gene encoding mitogen-activated protein kinase 1 (MAPK1) for the kinetoplast protozoan
Leishmania donovani
(LdMAPK1) that was consistently downregulated in antimony-resistant field isolates. The expression level of the gene was validated by real-time PCR. Furthermore, decreased expression of LdMAPK1 was also confirmed at the protein level in resistant isolates. Primary structure analysis of LdMAPK1 revealed the presence of all of the characteristic features of MAPK1. When expressed in
Escherichia coli
, the recombinant enzyme showed kinase activity with myelin basic protein as the substrate and was inhibited by staurosporine. Interestingly, overexpression of this gene in a drug-sensitive laboratory strain and a resistant field isolate resulted in increased the sensitivity of the transfectants to potassium antimony tartrate, suggesting that it has a role in antimony resistance. Our results demonstrate that downregulation of LdMAPK1 may be in part correlated with antimony drug resistance in Indian VL isolates.
Low Prevalence of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Isolates among Connecticut Veterans
Authors: Fink Susan L. , Martinello Richard A. , Campbell Sheldon M. , Murray Thomas S.
Published: November 2011

The Etest glycopeptide resistance detection identified two potential heterogeneous vancomycin-intermediate
Staphylococcus aureus
(hVISA) isolates from a screen of 288 methicillin-resistant
Staphylococcus aureus
(MRSA) isolates from patients at a Connecticut Veterans Hospital. However, the two isolates did not meet the criteria for hVISA by the population analysis profile-area under the curve analysis, arguing against routine screening for hVISA in this low prevalence population.
Simulated Antibiotic Exposures in an
In Vitro
Hollow-Fiber Infection Model Influence Toxin Gene Expression and Production in Community-Associated Methicillin-Resistant Staphylococcus aureus Strain MW2
Authors: Pichereau Solen , Pantrangi Madhulatha , Couet William , Badiou Cedric , Lina Gerard , Shukla Sanjay K. , Rose Warren E.
Published: November 2011

Community-associated methicillin-resistant
Staphylococcus aureus
(CA-MRSA) strain MW2 harbors a plethora of toxins to mediate its virulence. However, toxin expression and regulation with simulated clinical antimicrobial exposures are unclear. This study evaluated these relationships using an
in vitro
pharmacodynamic hollow-fiber infection model. Clinical doses of clindamycin, linezolid, minocycline, trimethoprim-sulfamethoxazole (SXT), and vancomycin were simulated over 72 h against MW2 in the hollow fiber model. Expression levels of
lukSF-PV
and enterotoxin genes
sec4
,
sek
,
seq
, and
sel2
were quantified by real-time PCR. Panton-Valentine leukocidin (PVL) was quantified by enzyme-linked immunosorbent assay (ELISA), and cytotoxicity was determined on polymorphonuclear cells (PMNs). Vancomycin produced the maximum MW2 killing (2.53 log
10
CFU/ml) after the first dose, but the greatest sustained killing over 72 h occurred with linezolid and clindamycin. Vancomycin and minocycline induced gene upregulation from 0 to 8 h, followed by downregulation for the remaining simulation period. Clindamycin decreased gene expression in the first 24 h, followed by moderate increases (2.5-fold) thereafter. Linezolid increased gene expression 11.4- to 200.4-fold but inhibited PVL production (0.6 ± 0.3 versus 5.9 ± 0.2 μg/ml, linezolid versus control at 72 h;
P
< 0.05). Similar effects on PVL production occurred with clindamycin and minocycline. SXT increased PVL production at 48 h (2.8-fold) and 72 h (4.9-fold) of treatment (
P
< 0.05), resulting in increased PVL cytotoxicity on PMNs. Linezolid, clindamycin, and minocycline were the most effective agents on decreasing the virulence potential in CA-MRSA, notably after 8 h of treatment. SXT had minimal effects on toxin gene regulation, but it increased production and cytotoxicity of PVL toxin in the model and may enhance virulence when it is used to treat severe infections.
Distribution of Spontaneous
gyrA
Mutations in 97 Fluoroquinolone-Resistant Helicobacter pylori Isolates Collected in France
Authors: Garcia Magali , Raymond Josette , Garnier Martine , Cremniter Julie , Burucoa Christophe
Published: November 2011

We determined the prevalence of
gyrA
mutations conferring fluoroquinolone resistance in 97
Helicobacter pylori
isolates collected in France from 2007 to 2010. Ninety-four harbored one or two mutations already found in the quinolone resistance determining region (QRDR) of
gyrA
(for T87I,
n
= 23; for N87K,
n
= 32; for D91N,
n
= 30; for D91G,
n
= 7; for D91Y,
n
= 6), 2 harbored a mutation never previously described (D91H and A88P), and one strain was resistant (ciprofloxacin MIC of 8 mg/liter) without a detected mutation conferring this resistance in
gyrA
or
gyrB
genes.
Zinc Acetate/Carrageenan Gels Exhibit Potent Activity
In Vivo
against High-Dose Herpes Simplex Virus 2 Vaginal and Rectal Challenge
Authors: Fernández-Romero José A. , Abraham Ciby J. , Rodriguez Aixa , Kizima Larisa , Jean-Pierre Ninochka , Menon Radhika , Begay Othell , Seidor Samantha , Ford Brian E. , Gil Pedro I. , Peters Jennifer , Katz David , Robbiani Melissa , Zydowsky Thomas M.
Published: November 2011

Topical microbicides that block the sexual transmission of HIV and herpes simplex virus 2 (HSV-2) are desperately needed to reduce the incidence of HIV infections worldwide. Previously we completed phase 3 testing of the carrageenan-based gel Carraguard. Although the trial did not show that Carraguard is effective in preventing HIV transmission during vaginal sex, it did show that Carraguard is safe when used weekly for up to 2 years. Moreover, Carraguard has
in vitro
activity against human papillomavirus (HPV) and HSV-2 and favorable physical and rheological properties, which makes it a useful vehicle to deliver antiviral agents such as zinc acetate. To that end, we previously reported that a prototype zinc acetate carrageenan gel protects macaques against vaginal challenge with combined simian-human immunodeficiency virus reverse transcriptase (SHIV-RT). Herein, we report the safety and efficacy of a series of zinc acetate and/or carrageenan gels. The gels protected mice (75 to 85% survival;
P
< 0.001) against high-dose (10
6
-PFU) HSV-2 vaginal or rectal challenge. In contrast, zinc acetate formulated in HEC (hydroxyethylcellulose; or the Universal Placebo) failed to protect mice against the high-dose vaginal HSV-2 challenge (similar to aqueous zinc acetate solution and the placebo controls). The gels were found to be effective spreading gels, exhibited limited toxicity
in vitro
, caused minimal damage to the architecture of the cervicovaginal and rectal mucosae
in vivo
, and induced no increased susceptibility to HSV-2 infection in a mouse model. Our results provide a strong rationale to further optimize and evaluate the zinc acetate/carrageenan gels for their ability to block the sexual transmission of HIV and HSV-2.
Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein
Authors: Giuntini Serena , Reason Donald C. , Granoff Dan M.
Published: November 2011

Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density.
Comparison of iron acquisition from Fe–pyoverdine by strategy I and strategy II plants
Authors: Shirley Matt , Avoscan Laure , Bernaud Eric , Vansuyt Gérard , Lemanceau Philippe
Published: November 2011

Iron is an essential micronutrient for plants and associated microorganisms. However, the bioavailability of iron in cultivated soils is low. Plants and microorganisms have thus evolved active strategies of iron uptake. Two different iron uptake strategies have been described in dicotyledonous and monocotyledonous graminaceous species. In bacteria, this strategy relies on the synthesis of siderophores. Pyoverdines, a major class of siderophores produced by fluorescent pseudomonads, were previously shown to promote iron nutrition of the dicotyledonous species Arabidopsis thaliana L. (Heynh.), whereas contradictory reports were made on the contribution of those siderophores to the nutrition of graminaceous annuals. Furthermore, no information has so far been available on graminaceous perennials. Here, the contribution of purified pyoverdine of Pseudomonas fluorescens C7R12 to the iron nutrition of two annual and perennial graminaceous plants was assessed and compared with that of two dicotyledonous plant species. Fe–Pyoverdine promoted the iron status of all plant species tested. With the exception of wheat, this promotion was more dramatic in graminaceous species than in dicotyledonous species and was the highest in fescue, a perennial species. The incorporation of 15N-labeled pyoverdine was consistent with the effect on the iron status of the plants tested.
Ecology and productivity of Cantharellus cibarius var. roseocanus in two eastern Canadian jack pine stands
Authors: Rochon Caroline , Paré David , Pélardy Nellia , Khasa Damase P. , Fortin J. André
Published: November 2011

Despite the economic importance of chanterelles, much remains to be known about their habitat requirements. Cantharellus cibarius var. roseocanus Redhead, Norvell & Danell sporocarp productivity was measured during three growing seasons in two Pinus banksiana Lamb. stands of boreal forest. The objective was to determine how the variability in stand, plant association, edaphic, and meteorological conditions was related to sporocarp productivity. DNA of this species was detected in organic and mineral soil horizons. Sporocarp productivity was similar for both stands, but the absence of colonies on trails at one of the sites likely reflects microenvironmental conditions that are unsuitable for chanterelle growth. Under the prevailing site conditions, preferred microhabitats were characterized by high stand density, high C:N ratio, and frequent moss presence. The Solidago puberula Nutt. – Comptonia peregrina (L.) Coulter – Pinus banksiana association, lichen presence, and as much clay and silt content as can possibly be found on this moderately acidic sandy soil favoured the productivity of this chanterelle, whereas ericaceous species presence was negatively correlated with chanterelle productivity. Positive correlations were found between total rainfall 1 week prior to fructification, air temperature 2 weeks prior to fructification, and sporocarp productivity. Results highlight the specific conditions favourable to Cantharellus cibarius var. roseocanus fructifications within these stands.
Photoionization of Al-like Si using the R-matrix method
Authors: Singh Jagjit , Aggarwal Sunny , Jha A.K.S. , Singh A.K. , Mohan M.
Published: November 2011

Relativistic calculations are made for photoionization of the ground state 3s23p ([Formula: see text]) and the lowest six excited states 3s23p ([Formula: see text]), 3s3p2 (4P1/2,3/2,5/2), and 3s3p2 (2D3/2,5/2) of Al-like Si, using the Breit–Pauli Hamiltonian within the R-matrix method. Cross sections are determined by the Rydberg series of autoionizing resonances converging to various ionic states. Relativistic effects as well as all the important physical effects like exchange, channel coupling, and short-range correlations have been considered in the present calculations. The present relativistic calculations for this ion using the lowest 20 target levels of Si III in the LSJ coupling scheme will enhance the database sufficiently for practical applications of photoionization cross sections of Si II.
The polylogarithm and the Lambert W functions in thermoelectrics
Authors: Molli Muralikrishna , Venkataramaniah K. , Valluri S.R.
Published: November 2011

In this work, we determine the conditions for the extremum of the figure of merit, θ2, in a degenerate semiconductor for thermoelectric (TE) applications. We study the variation of the function θ2 with respect to the reduced chemical potential μ* using relations involving polylogarithms of both integral and nonintegral orders. We present the relevant equations for the thermopower, thermal, and electrical conductivities that result in optimizing θ2 and obtaining the extremum equations. We discuss the different cases that arise for various values of r, which depends on the type of carrier scattering mechanism present in the semiconductor. We also present the important extremum conditions for θ2 obtained by extremizing the TE power factor and the thermal conductivity separately. In this case, simple functional equations, which lead to solutions in terms of the Lambert W function, result. We also present some solutions for the zeros of the polylogarithms. Our analysis allows for the possibility of considering the reduced chemical potential and the index r of the polylogarithm as complex variables.
The association between Northern Hemisphere climate patterns and interannual variability in Canadian wildfire activity
Authors: Beverly J.L. , Flannigan M.D. , Stocks B.J. , Bothwell P.
Published: November 2011

Wildfire impacts on ecological and socioeconomic systems are regulated, in part, by climate. Association between hemispheric-scale climate patterns and annual wildfire activity can be obscured by local factors that also control the initiation and spread of fires. Vegetation, topography, and fire suppression can be expected to influence conventional measures of annual wildfire activity such as area burned, effectively concealing evidence of broad-scale climate influences. This study investigates alternatives to area-burned statistics for quantifying annual wildfire activity in Canada in relation to Northern Hemisphere climate variability represented by the Atlantic Multidecadal Oscillation (AMO). We depart from conventional approaches by including socioeconomic measures of wildfire activity and by assessing spatially referenced wildfire data over units of observation chosen explicitly to diminish variability caused by factors unrelated to broad-scale climate. Our data-centred approach, combined with linear regression modelling, revealed that the AMO was positively correlated with national time series of very large fires (≥10 000 ha), wildfire-related evacuations, and fire suppression expenditures over the period 1975–2007. The AMO and wildfire activity were most closely coupled during a period of predominantly positive-phase Arctic Oscillation (AO) and Pacific Decadal Oscillation (PDO) between 1989 and 2001. Positive correlation between maximum evacuation wind speed and the AMO suggests that wind may be a causal factor in the AMO–wildfire relationship.
Movements of wintering American marten (Martes americana): relative influences of prey activity and forest stand age
Authors: Vigeant-Langlois Charles , Desrochers André
Published: November 2011

American marten (Martes americana (Turton, 1806)) was traditionally associated with old-growth forests, but recent evidence suggests that they are frequently found in younger forests as well. To better understand habitat requirements by this economically important furbearer, we investigated its fine-scale movement behavior in relation to local prey activity (tracks) and stand age. We georeferenced 34 marten tracks (57 km), associated prey tracks, and subnivean forays in a balsam fir forest of southern Québec, Canada. Marten movements were more tortuous in the presence of high numbers of prey tracks and near subnivean foraging sites. The latter relationships were stronger at a fine spatial scale (10 m movement steps) than at coarser scales (20 or 40 m movement steps). Marten movement tortuosity was unrelated to forest stand age after accounting for prey activity. These results support the hypothesis that the American marten does not hunt mainly in old-growth forests but appears to concentrate its foraging behaviour in areas with high prey activity.
Using rich social media information for music recommendation via hypergraph model
Authors: Tan Shulong , Bu Jiajun , Chen Chun , Xu Bin , Wang Can , He Xiaofei
Published: November 2011

There are various kinds of social media information, including different types of objects and relations among these objects, in music social communities such as Last.fm and Pandora. This information is valuable for music recommendation. However, there are two main challenges to exploit this rich social media information: (a) There are many different types of objects and relations in music social communities, which makes it difficult to develop a unified framework taking into account all objects and relations. (b) In these communities, some relations are much more sophisticated than pairwise relation, and thus cannot be simply modeled by a graph. We propose a novel music recommendation algorithm by using both multiple kinds of social media information and music acoustic-based content. Instead of graph, we use hypergraph to model the various objects and relations, and consider music recommendation as a ranking problem on this hypergraph. While an edge of an ordinary graph connects only two objects, a hyperedge represents a set of objects. In this way, hypergraph can be naturally used to model high-order relations.
Video accessibility enhancement for hearing-impaired users
Authors: Hong Richang , Wang Meng , Yuan Xiao-Tong , Xu Mengdi , Jiang Jianguo , Yan Shuicheng , Chua Tat-Seng
Published: November 2011

There are more than 66 million people suffering from hearing impairment and this disability brings them difficulty in video content understanding due to the loss of audio information. If the scripts are available, captioning technology can help them in a certain degree by synchronously illustrating the scripts during the playing of videos. However, we show that the existing captioning techniques are far from satisfactory in assisting the hearing-impaired audience to enjoy videos. In this article, we introduce a scheme to enhance video accessibility using a
Dynamic Captioning
approach, which explores a rich set of technologies including face detection and recognition, visual saliency analysis, text-speech alignment, etc. Different from the existing methods that are categorized as static captioning, dynamic captioning puts scripts at suitable positions to help the hearing-impaired audience better recognize the speaking characters. In addition, it progressively highlights the scripts word-by-word via aligning them with the speech signal and illustrates the variation of voice volume. In this way, the special audience can better track the scripts and perceive the moods that are conveyed by the variation of volume. We implemented the technology on 20 video clips and conducted an in-depth study with 60 real hearing-impaired users. The results demonstrated the effectiveness and usefulness of the video accessibility enhancement scheme.
Automatic creation of photo books from stories in social media
Authors: Rabbath Mohamad , Sandhaus Philipp , Boll Susanne
Published: November 2011

Photos are a special way to tell stories of our best memories and moments. The representation of those photos in appealing physical photo books is highly appreciated by many people. Today, many photos are shared via social networking sites, where people upload their photos and share their stories with their friends. The members of social networks comment on each other's photos, add tags or descriptions and upload new photos of the same events to their albums. While the media of different personal events are available on the social network, there is no easy way to collect and bundle them into a story and print this story as a photo book. We propose an approach to automatically detect media elements that match a query (where, when, what, who) in the user's social network and intelligently arrange and compose them into a printable photo book. We combine content analysis of text and images to automatically and semi-automatically select photos of a specific story. We calculate the probabilities of each two photos to belong to the same event using an Expectation-Maximization algorithm that we propose in order to be able to retrieve them easily when receiving the user queries, and we address the differences between our model and other models that use similar proposed algorithms. People's tags and the interaction between the users and the photos as well as other semantic information are exploited to select important photos that are suitable to create the photo book. The selected photos and derived semantics are then employed to automatically create an appealing layout for the photo book.