bluuebunny/crossref_metadata_2025 huggingface dataset:
Cascaded analysis of signal and noise propagation through a heterogeneous breast model
Authors: Mainprize James G. , Yaffe Martin J.
Published: September 2010

Purpose:

The detectability of lesions in radiographic images can be impaired by patterns caused by the surrounding anatomic structures. The presence of such patterns is often referred to as anatomic noise. Others have previously extended signal and noise propagation theory to include variable background structure as an additional noise term and used in simulations for analysis by human and ideal observers. Here, the analytic forms of the signal and noise transfer are derived to obtain an exact expression for any input random distribution and the “power law” filter used to generate the texture of the tissue distribution.

Methods:

A cascaded analysis of propagation through a heterogeneous model is derived for x‐ray projection through simulated heterogeneous backgrounds. This is achieved by considering transmission through the breast as a correlated amplification point process. The analytic forms of the cascaded analysis were compared to monoenergetic Monte Carlo simulations of x‐ray propagation through power law structured backgrounds.

Results:

As expected, it was found that although the quantum noise power component scales linearly with the x‐ray signal, the anatomic noise will scale with the square of the x‐ray signal. There was a good agreement between results obtained using analytic expressions for the noise power and those from Monte Carlo simulations for different background textures, random input functions, and x‐ray fluence.

Conclusions:

Analytic equations for the signal and noise properties of heterogeneous backgrounds were derived. These may be used in direct analysis or as a tool to validate simulations in evaluating detectability.
Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detectora)
Authors: Minamisawa R. A. , Rubo R. A. , Seraide R. M. , Rocha J. R. O. , Almeida A.
Published: September 2010

Purpose: Several attempts to determine the transit time of a high dose rate (HDR) brachytherapy unit have been reported in the literature with controversial results. The determination of the source speed is necessary to accurately calculate the transient dose in brachytherapy treatments. In these studies, only the average speed of the source was measured as a parameter for transit dose calculation, which does not account for the realistic movement of the source, and is therefore inaccurate for numerical simulations. The purpose of this work is to report the implementation and technical design of an optical fiber based detector to directly measure the instantaneous speed profile of a source in a Nucletron HDR brachytherapy unit.

Methods: To accomplish this task, we have developed a setup that uses the Cerenkov light induced in optical fibers as a detection signal for the radiation source moving inside the HDR catheter. As the source travels between two optical fibers with known distance, the threshold of the induced signals are used to extract the transit time and thus the velocity. The high resolution of the detector enables the measurement of the transit time at short separation distance of the fibers, providing the instantaneous speed.

Results: Accurate and high resolution speed profiles of the radiation source traveling from the safe to the end of the catheter and between dwell positions are presented. The maximum and minimum velocities of the source were found to be and . The authors demonstrate that the radiation source follows a uniformly accelerated linear motion with acceleration of . In addition, the authors compare the average speed measured using the optical fiber detector to those obtained in the literature, showing deviation up to 265%.

Conclusions: To the best of the authors’ knowledge, the authors directly measured for the first time the instantaneous speed profile of a radiation source in a HDR brachytherapy unit traveling from the unit safe to the end of the catheter and between interdwell distances. The method is feasible and accurate to implement on quality assurance tests and provides a unique database for efficient computational simulations of the transient dose.
Normalized metal artifact reduction (NMAR) in computed tomography
Authors: Meyer Esther , Raupach Rainer , Lell Michael , Schmidt Bernhard , Kachelrieß Marc
Published: September 2010

Purpose:While modern clinical CT scanners under normal circumstances produce high quality images, severe artifacts degrade the image quality and the diagnostic value if metal prostheses or other metal objects are present in the field of measurement. Standard methods for metal artifact reduction (MAR) replace those parts of the projection data that are affected by metal (the so‐called metal trace or metal shadow) by interpolation. However, while sinogram interpolation methods efficiently remove metal artifacts, new artifacts are often introduced, as interpolation cannot completely recover the information from the metal trace. The purpose of this work is to introduce a generalized normalization technique for MAR, allowing for efficient reduction of metal artifacts while adding almost no new ones. The method presented is compared to a standard MAR method, as well as MAR using simple length normalization.

Methods:In the first step, metal is segmented in the image domain by thresholding. A 3D forward projection identifies the metal trace in the original projections. Before interpolation, the projections are normalized based on a 3D forward projection of a prior image. This prior image is obtained, for example, by a multithreshold segmentation of the initial image. The original rawdata are divided by the projection data of the prior image and, after interpolation, denormalized again. Simulations and measurements are performed to compare normalized metal artifact reduction (NMAR) to standard MAR with linear interpolation and MAR based on simple length normalization.

Results:Promising results for clinical spiral cone‐beam data are presented in this work. Included are patients with hip prostheses, dental fillings, and spine fixation, which were scanned at pitch values ranging from 0.9 to 3.2. Image quality is improved considerably, particularly for metal implants within bone structures or in their proximity. The improvements are evaluated by comparing profiles through images and sinograms for the different methods and by inspecting ROIs. NMAR outperforms both other methods in all cases. It reduces metal artifacts to a minimum, even close to metal regions. Even for patients with dental fillings, which cause most severe artifacts, satisfactory results are obtained with NMAR. In contrast to other methods, NMAR prevents the usual blurring of structures close to metal implants if the metal artifacts are moderate.

Conclusions:NMAR clearly outperforms the other methods for both moderate and severe artifacts. The proposed method reliably reduces metal artifacts from simulated as well as from clinical CT data. Computationally efficient and inexpensive compared to iterative methods, NMAR can be used as an additional step in any conventional sinogram inpainting‐based MAR method.
Dose modeling in ultraviolet phototherapy
Authors: Grimes David Robert , Robbins Chris , O'Hare Neil John
Published: September 2010

Purpose:

Ultraviolet phototherapy is widely used in the treatment of numerous skin conditions. This treatment is well established and largely beneficial to patients on both physical and psychological levels; however, overexposure to ultraviolet radiation (UVR) can have detrimental effects, such as erythemal responses and ocular damage in addition to the potentially carcinogenic nature of UVR. For these reasons, it is essential to control and quantify the radiation dose incident upon the patient to ensure that it is both biologically effective and has the minimal possible impact on the surrounding unaffected tissue.

Methods:

To date, there has been little work on dose modeling, and the output of artificial UVR sources is an area where research has been recommended. This work characterizes these sources by formalizing an approach from first principles and experimentally examining this model.

Results:

An implementation of a line source model is found to give impressive accuracy and quantifies the output radiation well.

Conclusions:

This method could potentially serve as a basis for a full computational dose model for quantifying patient dose.
Higher‐order phase shift reconstruction approach
Authors: Cong Wenxiang , Wang Ge
Published: September 2010

Purpose:

Biological soft tissues encountered in clinical and preclinical imaging mainly consists of atoms of light elements with low atomic numbers and their elemental composition is nearly uniform with little density variation. Hence, x‐ray attenuation contrast is relatively poor and cannot achieve satisfactory sensitivity and specificity. In contrast, x‐ray phase‐contrast provides a new mechanism for soft tissue imaging. The x‐ray phase shift of soft tissues is about a thousand times greater than the x‐ray absorption over the diagnostic x‐ray energy range, yielding a higher signal‐to‐noise ratio than the attenuation contrast counterpart. Thus, phase‐contrast imaging is a promising technique to reveal detailed structural variation in soft tissues, offering a high contrast resolution between healthy and malignant tissues. Here the authors develop a novel phase retrieval method to reconstruct the phase image on the object plane from the intensity measurements. The reconstructed phase image is a projection of the phase shift induced by an object and serves as input to reconstruct the 3D refractive index distribution inside the object using a tomographic reconstruction algorithm. Such x‐ray refractive index images can reveal structural features in soft tissues, with excellent resolution differentiating healthy and malignant tissues.

Methods:

A novel phase retrieval approach is proposed to reconstruct an x‐ray phase image of an object based on the paraxial Fresnel–Kirchhoff diffraction theory. A primary advantage of the authors’ approach is higher‐order accuracy over that with the conventional linear approximation models, relaxing the current restriction of slow phase variation. The nonlinear terms in the autocorrelation equation of the Fresnel diffraction pattern are eliminated using intensity images measured at different distances in the Fresnel diffraction region, simplifying the phase reconstruction to a linear inverse problem. Numerical experiments are performed to demonstrate the accuracy and stability of the proposed approach.

Results:

The proposed reconstruction formula is a generalization of the transport of intensity equation (TIE). It has the second‐order accuracy compared to the linear model used in the conventional phase retrieval approach. The numerical experiments demonstrate that the accuracy and stability of the proposed phase reconstruction method outperforms the TIE‐based reconstruction method.

Conclusions:

A novel approach has been proposed to retrieve an x‐ray phase shift image induced by an object from intensity images measured at different distances in the Fresnel diffraction region. The authors’ approach has the second‐order accuracy and is able to retrieve the phase shift of an object stably, overcoming the restriction of slow phase variation assumed by the conventional phase retrieval techniques.
Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams
Authors: Wang Lilie L. W. , Klein David , Beddar A. Sam
Published: September 2010

Purpose:

By using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams.

Methods:

Three PSDs were modeled in this study: A plastic scintillator (BC‐400) and a scintillating fiber (BCF‐12), both attached by a plastic‐core optical fiber stem, and a plastic scintillator (BC‐400) attached by an air‐core optical fiber stem with a silica tube coated with silver. The authors then calculated, with low statistical uncertainty, the energy and angular dependences of the PSDs’ responses in a water phantom. For energy dependence, the response of the detectors is calculated as the detector dose per unit water dose. The perturbation caused by the optical fiber stem connected to the PSD to guide the optical light to a photodetector was studied in simulations using different optical fiber materials.

Results:

For the energy dependence of the PSDs in photon beams, the PSDs with plastic‐core fiber have excellent energy independence within about 0.5% at photon energies ranging from 300 keV (monoenergetic) to 18 MV (linac beam). The PSD with an air‐core optical fiber with a silica tube also has good energy independence within 1% in the same photon energy range. For the angular dependence, the relative response of all the three modeled PSDs is within 2% for all the angles in a 6 MV photon beam. This is also true in a 300 keV monoenergetic photon beam for PSDs with plastic‐core fiber. For the PSD with an air‐core fiber with a silica tube in the 300 keV beam, the relative response varies within 1% for most of the angles, except in the case when the fiber stem is pointing right to the radiation source in which case the PSD may over‐response by more than 10%.

Conclusions:

At ±1% level, no beam energy correction is necessary for the response of all three PSDs modeled in this study in the photon energy ranges from 200 keV (monoenergetic) to 18 MV (linac beam). The PSD would be even closer to water equivalent if there is a silica tube around the sensitive volume. The angular dependence of the response of the three PSDs in a 6 MV photon beam is not of concern at 2% level.
Experimental determination of the radial dose distribution in high gradient regions around wires: Comparison of electron paramagnetic resonance imaging, films, and Monte Carlo simulations
Authors: Kolbun N. , Levêque Ph. , Abboud F. , Bol A. , Vynckier S. , Gallez B.
Published: September 2010

Purpose:

The experimental determination of doses at proximal distances from radioactive sources is difficult because of the steepness of the dose gradient. The goal of this study was to determine the relative radial dose distribution for a low dose rate wire source using electron paramagnetic resonance imaging (EPRI) and to compare the results to those obtained using Gafchromic EBT film dosimetry and Monte Carlo (MC) simulations.

Methods:

Lithium formate and ammonium formate were chosen as the EPR dosimetric materials and were used to form cylindrical phantoms. The dose distribution of the stable radiation‐induced free radicals in the lithium formate and ammonium formate phantoms was assessed by EPRI. EBT films were also inserted inside in ammonium formate phantoms for comparison. MC simulation was performed using theMCNP4C2 software code.

Results:

The radical signal in irradiated ammonium formate is contained in a single narrow EPR line, with an EPR peak‐to‐peak linewidth narrower than that of lithium formate ( and 1.4 mT, respectively). The spatial resolution of EPR images was enhanced by a factor of 2.3 using ammonium formate compared to lithium formate because its linewidth is about 0.75 mT narrower than that of lithium formate. The EPRI results were consistent to within 1% with those of Gafchromic EBT films and MC simulations at distances from 1.0 to 2.9 mm. The radial dose values obtained by EPRI were about 4% lower at distances from 2.9 to 4.0 mm than those determined by MC simulation and EBT film dosimetry.

Conclusions:

Ammonium formate is a suitable material under certain conditions for use in brachytherapy dosimetry using EPRI. In this study, the authors demonstrated that the EPRI technique allows the estimation of the relative radial dose distribution at short distances for a wire source.
Surface applicator calibration and commissioning of an electronic brachytherapy system for nonmelanoma skin cancer treatmenta)
Authors: Rong Yi , Welsh James S.
Published: September 2010

Purpose:

The Xoft Axxent® x‐ray source has been used for treating nonmelanoma skin cancer since the surface applicators became clinically available in 2009. The authors report comprehensive calibration procedures for the electronic brachytherapy (eBx) system with the surface applicators.

Methods:

The Xoft miniature tube (model S700) generates 50 kVp low‐energy x rays. The new surface applicators are available in four sizes of 10, 20, 35, and 50 mm in diameter. The authors’ tests include measurements of dose rate, air‐gap factor, output stability, depth dose verification, beam flatness and symmetry, and treatment planning with patient specific cutout factors. The TG‐61 in‐air method was used as a guideline for acquiring nominal dose‐rate output at the skin surface. A soft x‐ray parallel‐plate chamber (PTW T34013) and electrometer was used for the output commissioning. GafChromic® EBT films were used for testing the properties of the treatment fields with the skin applicators. Solid water slabs were used to verify the depth dose and cutout factors. Patients with basal cell or squamous cell carcinoma were treated with eBx using a calibrated Xoft system with the low‐energy x‐ray source and the skin applicators.

Results:

The average nominal dose‐rate output at the skin surface for the 35 mm applicator is 1.35 Gy/min with ±5% variation for 16 sources. The dose‐rate output and stability (within ±5% variation) were also measured for the remaining three applicators. For the same source, the output variation is within 2%. The effective source‐surface distance was calculated based on the air‐gap measurements for four applicator sizes. The field flatness and symmetry are well within 5%. Percentage depth dose in water was provided by factory measurements and can be verified using solid water slabs. Treatment duration was calculated based on the nominal dose rate, the prescription fraction size, the depth dose percentage, and the cutout factor. The output factor needs to be measured for each case with varying shapes of cutouts.

Conclusions:

Together with TG‐61, the authors’ methodology provides comprehensive calibration procedures for medical physicists for using the Xoft eBx system and skin applicators for nonmelanoma skin cancer treatments.
Quantitative comparison of thermal dose models in normal canine brain
Authors: Yung Joshua P. , Shetty Anil , Elliott Andrew , Weinberg Jeffrey S. , McNichols Roger J. , Gowda Ashok , Hazle John D. , Stafford R. Jason
Published: September 2010

Purpose:

Minimally invasive thermal ablative therapies as alternatives to conventional surgical management of solid tumors and other pathologies is increasing owing to the potential benefits of performing these procedures in an outpatient setting with reduced complications and comorbidity. Magnetic resonance temperature imaging (MRTI) measurement allows existing thermal dose models to use the spatiotemporal temperature history to estimate the thermal damage to tissue. However, the various thermal dose models presented in the literature employ different parameters and thresholds, affecting the reliability of thermal dosimetry. In this study, the authors quantitatively compared three thermal dose models (Arrhenius rate process,, and threshold temperature) using the dice similarity coefficient (DSC).

Methods:

The DSC was used to compare the spatial overlap between the region of thermal damage as predicted by the models forin vivo normal canine brain during thermal therapy to the region of thermal damage as revealed by contrast‐enhanced T1‐weighted images acquired immediately after therapy . The outer edge of the hyperintense rim of the ablation region was used as the surrogate marker for the limits of thermal coagulation. The DSC was also used to investigate the impact of varying the thresholds on each models’ ability to predict the zone of thermal necrosis.

Results:

At previously reported thresholds, the authors found that all three models showed good agreement (defined as) with post‐treatment imaging. All three models examined across the range of commonly applied thresholds consistently showed highly accurate spatial overlap, low variability, and little dependence on temperature uncertainty. DSC values corresponding to cited thresholds were not significantly different from peak DSC values.

Conclusions:

Thus, the authors conclude that the all three thermal dose models can be used as a reliable surrogate for postcontrast tissue damage verification imaging in rapid ablation procedures and can also be used to enhance the capability of MRTI to control thermal therapy in real time.
Iterative reconstruction of Fourier‐rebinned PET data using sinogram blurring function estimated from point source scans
Authors: Tohme Michel S. , Qi Jinyi
Published: September 2010

Purpose:

The accuracy of the system model that governs the transformation from the image space to the projection space in positron emission tomography (PET) greatly affects the quality of reconstructed images. For efficient computation in iterative reconstructions, the system model in PET can be factored into a product of geometric projection and sinogram blurring function. To further speed up reconstruction, fully 3D PET data can be rebinned into a stack of 2D sinograms and then be reconstructed using 2D iterative algorithms. The purpose of this work is to develop a method to estimate the sinogram blurring function to be used in reconstruction of Fourier‐rebinned data.

Methods:

In a previous work, the authors developed an approach to estimating the sinogram blurring function of nonrebinned PET data from experimental scans of point sources. In this study, the authors extend this method to the estimation of sinogram blurring function for Fourier‐rebinned PET data. A point source was scanned at a set of sampled positions in the microPET II scanner. The sinogram blurring function is considered to be separable between the transaxial and axial directions. A radially and angularly variant 2D blurring function is estimated from Fourier‐rebinned point source scans to model the transaxial blurring with consideration of the detector block structure of the scanner; a space‐variant 1D blurring kernel along the axial direction is estimated separately to model the correlation between neighboring planes due to detector intrinsic blurring and Fourier rebinning. The estimated sinogram blurring function is incorporated in a 2D maximuma posteriori (MAP) reconstruction algorithm for image reconstruction.

Results:

Physical phantom experiments were performed on the microPET II scanner to validate the proposed method. The authors compared the proposed method to 2D MAP reconstruction without sinogram blurring model and 2D MAP reconstruction with a Monte Carlo based blurring model. The results show that the proposed method produces images with improved contrast and spatial resolution. The reconstruction time is unaffected by the new method since the blurring component takes a relatively negligible part of the overall reconstruction time.

Conclusions:

The proposed method can estimate sinogram blurring matrix for Fourier‐rebinned PET data and can be used to improve contrast and spatial resolution of reconstructed images. The method can be applied to other human and animal scanners.
Why University-Industry Partnerships Matter
Authors: Boccanfuso Anthony M.
Published: September 2010

Optimizing the process by which discoveries are translated to innovative products requires enhanced links between academia and industry.
Bacterial Exploitation of Host Cell Signaling
Authors: Lu Richard , Goldberg Marcia B.
Published: September 2010

A new bacterial phosphatase that perturbs host-cell signaling circuits highlights a class of pathogen proteins that may serve as potent therapeutic targets.
Improving Stem Cell Survival, One Hurdle at a Time
Authors: Ahmad Shama
Published: September 2010

Inhibition of nonmuscle myosin II improves survival and supports self-renewal of human pluripotent stem cells.
Rewiring the Brain After Stroke
Authors: Minzenberg Michael J.
Published: September 2010

A new study finds altered communication between the brain’s hemispheres after stroke.
Multiplex Assay Detection of Immunoglobulin G Antibodies That RecognizeGiardia intestinalisandCryptosporidium parvumAntigens
Authors: Priest Jeffrey W. , Moss Delynn M. , Visvesvara Govinda S. , Jones Cara C. , Li Anna , Isaac-Renton Judith L.
Published: September 2010

Giardiasis and cryptosporidiosis are common enteric parasitic diseases that have similar routes of transmission. In this work, we have identified epitopes within theGiardiavariant-specific surface protein (VSP) sequences that are recognized by IgG antibodies from 13 of 14 (93%) sera from patients with stool-confirmed giardiasis. The conserved epitopes are shared among VSPs from both of the assemblages that commonly infect humans, and they are likely to be structural, as both sodium dodecyl sulfate treatment and dithiothreitol reduction decrease antibody recognition. In a multiplex bead assay (MBA), we used three VSP fragments from an assemblage AGiardiastrain, three VSP fragments from assemblage B strains, and the α-1 giardin structural antigen to detect IgG antibodies toGiardiaand used the recombinant 17- and 27-kDa antigens to simultaneously detect IgG antibodies toCryptosporidium. The MBA differentiated between sera fromGiardiaandCryptosporidiumoutbreaks and also identified a giardiasis outbreak that may have included cryptosporidiosis cases. Approximately 40% of cryptosporidiosis outbreak samples had high MBA responses for both the 27- and 17-kDa antigens, while <10% of nonoutbreak and giardiasis outbreak samples had high responses. At least 60% of giardiasis outbreak samples were positive for antibodies to multipleGiardiaantigens, while ≤12% of nonoutbreak samples and samples from U.S. and British Columbia cryptosporidiosis outbreaks met our definition forGiardiaseropositivity. A MBA using multiple parasite antigens may prove useful in the epidemiologic analysis of future waterborne or food-borne outbreaks of diarrheal disease.
Preexisting Antibody Response against 2009 Pandemic Influenza H1N1 Viruses in the Taiwanese Population
Authors: Chi Chia-Yu , Liu Ching-Chuan , Lin Chia-Chun , Wang Hsuan-Chen , Cheng Yung-Tsung , Chang Chung-Ming , Wang Jen-Ren
Published: September 2010

A novel pandemic influenza H1N1 (pH1N1) virus spread rapidly across the world in 2009. Due to the important role of antibody-mediated immunity in protection against influenza infection, we used an enzyme-linked immunosorbent assay-based microneutralization test to investigate cross-reactive neutralizing antibodies against the 2009 pH1N1 virus in 229 stored sera from donors born between 1917 and 2008 in Taiwan. The peak of cumulative geometric mean titers occurred in donors more than 90 years old and declined sharply with decreasing age. Sixteen of 27 subjects (59%) more than 80 years old had cross-reactive antibody titers of 160 or more against the 2009 pH1N1 virus, whereas none of the donors from age 9 to 49 had an antibody titer of 160 or more. Interestingly, 2 of 51 children (4%) from 6 months to 9 years old had an antibody titer of 40. We further tested the antibody responses in 9 of the 51 pediatric sera to three endemic seasonal influenza viruses isolated in 2006 and 2008 in Taiwan, and the results showed that only the 2 sera from children with antibody responses to the 2009 pH1N1 virus had high titers of neutralizing antibody against recent seasonal influenza virus strains. Our study shows the presence of some level of cross-reactive antibody in Taiwanese persons 50 years old or older, and the elderly subjects who may already have been exposed to the 1918 virus had high titers of neutralizing antibody to the 2009 pH1N1 virus. Our data also indicate that natural infection with the Taiwan 2006 and 2008 seasonal H1N1 viruses may induce a cross-reactive antibody response to the 2009 pH1N1 virus.
The effect on collisions with injuries of a reduction in traffic citations issued by police officers
Authors: Blais Étienne , Gagné Marie-Pier
Published: September 2010

Objective

To assess the effect on collisions with injuries of a 61% reduction in the number of traffic citations issued by police officers over a 21-month period.

Methods

Using descriptive analyses as well as ARIMA intervention time-series analyses, this study estimated the impact of this reduction in citations issued for traffic violations on the monthly number of collisions with injuries.

Results

Simple descriptive analysis reveals that the 61% reduction in the number of citations issued for traffic violations during the experimental period coincided with an increase in collisions with injuries. Results from the interrupted time-series analyses reveal that, on average, eight additional collisions with injuries occurred every month during which the number of tickets issued for traffic violations was lower than normal. As this pressure tactic was applied for 21 months, it is estimated that this situation was associated with approximately 184 additional collisions with injuries: equivalent to 239 traffic injuries (either deaths, minor or serious injuries).

Conclusion

In the province of Quebec, police officers are an important component of road safety policy. Issuing citations prevents drivers from adopting reckless driving habits such as speeding, running red lights and failing to fasten their seat belt.
The association of road safety knowledge and risk behaviour with paediatric road traffic injury in Guangzhou, China
Authors: Dong Xiaomei , Peek-Asa Corinne , Yang Jingzhen , Wang Shengyong , Chen Xiongfei , Chi Guibo , Ramirez Marizen
Published: September 2010

Background

This study describes road traffic injuries among school-aged children in Guangzhou, China, and examines the effect of road safety knowledge and risk behaviours on road traffic injuries.

Methods

A stratified cluster sample of 3747 children from six primary schools and six middle schools in Guangzhou, China, was surveyed. Data were collected on sociodemographic factors and road traffic injuries during the past year. Knowledge about road safety rules was assessed using a 14-item road safety knowledge index, and risky road safety behaviours were measured using a 25-item road safety behaviour index.

Results

A total of 403 (10.8%) students reported having at least one road traffic injury during the past 12 months. A high proportion of injuries was found among children who were boys, in primary school and from the suburbs. Bicycle-related injuries were the most common (46.0% of all injuries). Motor vehicle-related injuries had higher hospitalisation rates and worse psychological impact than bicycle or pedestrian injuries. Children with low and medium road safety knowledge had 1.5 to 3 times the odds of injury compared with students with high road safety knowledge. Students with high scores on the risky road behaviour index had twice the odds of injury (OR 2.04, 95% CI 1.47 to 2.84) compared with students with low scores.

Conclusion

Better road safety knowledge and the avoidance of walking or cycling-related risk behaviours are protective factors for road traffic injuries among Chinese school children. More injury prevention programmes are needed to improve road safety knowledge and reduce risk behaviours.
Adolescent development and risk of injury: using developmental science to improve interventions: Figure 1
Authors: Johnson Sara B , Jones Vanya C
Published: September 2010

In adolescence, there is a complex interaction among physical, cognitive, and psychosocial developmental processes, culminating in greater risk-taking and novelty-seeking. Concurrently, adolescents face an increasingly demanding environment, which results in heightened vulnerability to injury. In this paper, we provide an overview of developmental considerations for adolescent injury interventions based on developmental science, including findings from behavioural neuroscience and psychology. We examine the role that typical developmental processes play in the way adolescents perceive and respond to risk and how this integrated body of developmental research adds to our understanding of how to do injury prevention with adolescents. We then highlight strategies to improve the translation of developmental research into adolescent injury prevention practice, calling on examples of existing interventions including graduated driver licensing.
Child pedestrian injuries and urban change
Authors: Yiannakoulias Nikolaos , Scott Darren M , Rowe Brian H , Voaklander Donald C
Published: September 2010

Background

The health impacts of rapid changes in urban environments due to economic growth and/or retraction are not widely known. This study looks at the effects of urban change on the risk of child pedestrian injury in Edmonton, Alberta, a city that has experienced large economic and population growth following the expansion of the oil and gas industry in Canada.

Methods

A longitudinal ecological study design was used to model the relationships between several built and social environmental variables and the risk of child pedestrian injury and severe child pedestrian injury between 1996 and 2007.

Results

The incidence of child pedestrian injury was stable, but the incidence of severe injury increased over the study period. Areas with higher proportions of families on low incomes had higher injury incidence. While new residential development is associated with a lower incidence of injury in most areas, in poor areas, new residential development is associated with a higher incidence, even after controlling for urban planning features and traffic intensity.

Conclusion

While suburban areas have a lower incidence of child pedestrian injury, residential development in poorer areas is associated with a higher child pedestrian injury risk. Child pedestrians may be less able to adapt to changes in the urban environment due to rapid growth and increasing income, and as a result, may be at greater risk of injury.
Comparative DFT study for molecular geometries and spectra of methyl pheophorbides-a: test of M06-2X and two other functionals
Authors: Huh Do Sung , Choe Sang Joon
Published: September 2010

The recent interest in the application of density functional theory (DFT) has prompted us to test several functions in molecular geometries of methyl pheophorbides-a (MPa), an important starting material in photodynamic therapy (PDT). In this study, we report on tests for three popular DFT methods: M06-2X, B3LYP, and LSDA. Based on the standard deviation and the mean value, and by using the difference between optimized calculated value and experimental value in geometries, we drew the following conclusions: M06-2X/6-311+G(d,p) attained the smallest standard deviation of difference among the tested DFT methods in terms of bond length, whereas the standard deviation of bond angle in LSDA/6-311+G(d,p) was the smallest. In terms of absolute value, the mean value of LSDA/6-311+G(d,p) calculation was larger than that of M06-2X/6-311+G(d,p). We found that M06-2X/6-311+G(d,p) gave the best performance for MPa in the molecular geometries. The UV-visible spectrum was calculated with time-dependent density-functional theory (TD-DFT). Time-dependent M06-2X/6-311+G(d,p) gave the best performance for MPa in CH2Cl2 solution. In general, TD-DFT calculations in CH2Cl2 solution were more red-shifted compared with those in the solid state.
Electrochemical, spectroscopic and microscopic studies of new manganese phthalocyanine complexes in solution and as self-assembled monolayers on gold
Authors: Coates Megan , Antunes Edith , Nyokong Tebello
Published: September 2010

Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
ATOMISTICALLY-INFORMED MESOSCALE MODEL OF DEFORMATION AND FAILURE OF BIOINSPIRED HIERARCHICAL SILICA NANOCOMPOSITES
Authors: SEN DIPANJAN , BUEHLER MARKUS J.
Published: September 2010

Structural hierarchies are universal design paradigms of biological materials, e.g., several materials in nature used for carrying mechanical load or impact protection such as bone, nacre, dentin show structural design at multiple length scales from the nanoscale to the macroscale. Another example is the case of diatoms, microscopic mineralized algae with intricately patterned silica-based exoskeletons, with substructure from the nanometer to micrometer length scale. Previous studies on silica nano-honeycomb structures inspired from these diatom substructures at the nanoscale have shown a great improvement in plasticity, ductility and toughness through these designs over macroscopic silica, though along with a substantial reduction in stiffness. Here, we extend the study of these structural designs to the micron length scale by introducing additional hierarchy levels to implement a multilevel composite design. To facilitate our computational experiments we first develop a mesoscale particle-spring model description of the mechanics of bulk silica/nano-honeycomb silica composites. Our mesoscale description is directly derived from constitutive material behavior found through atomistic simulations at the nanoscale with the first principles-based ReaxFF force field, but is capable of describing deformation and failure of silica materials at tens of micrometer length scales. We create several models of randomly-dispersed fiber-composite materials with a small volume fraction of the nano-honeycomb phase, and analyze the fracture mechanics using J-integral and R-curve studies. Our simulations show a dominance of quasi-brittle fracture behavior in all cases considered. For particular materials with a small volume fraction of the nano-honeycomb phase dispersed as fibers within a bulk silica matrix, we find a large improvement (≈4.4 times) in toughness over bulk silica, while retaining the high stiffness (to 70%) of the material. The increase in toughness is observed to arise primarily from crack path deflection and crack bridging by the nano-honeycomb fibers. The first structural hierarchy at the nanometer scale (nano-honeycomb silica) provides large improvements in ductility and toughness at the cost of a large reduction in stiffness. The second structural hierarchy at the micron length scale (bulk silica/nano-honeycomb composite) recovers the stiffness of bulk silica while substantially improving its toughness. The results reported here provide direct evidence that structural hierarchies present a powerful design paradigm to obtain heightened levels of stiffness and toughness from multiscale engineering a single brittle — and by itself a functionally inferior material — without the need to introduce organic (e.g., protein) phases. Our model sets the stage for the direct simulation of multiple hierarchical levels to describe deformation and failure of complex biological composites.
Vitamin D homeostasis is compromised due to increased urinary excretion of the 25-hydroxycholecalciferol-vitamin D-binding protein complex in the Zucker diabetic fatty rat
Authors: Anderson R. L. , Ternes S. B. , Strand K. A. , Rowling M. J.
Published: September 2010

Altered serum concentrations of the major circulating form of vitamin D [25-hydroxycholecalciferol (25D3)] and its active hormone derivative [1,25-dihydroxycholecalciferol (1,25D3)] have been linked to non-insulin-dependent diabetes mellitus (NIDDM). However, a mechanistic basis for this occurrence has not been fully elucidated. Normally, renal reabsorption of vitamin D-binding protein-bound 25D3absolutely requires receptor-mediated endocytosis via a receptor complex containing megalin, cubilin, and disabled-2 (Dab2), whereas an absence of megalin or its endocytic partners can lead to a marked urinary loss of 25D and severe vitamin D deficiency. Therefore, we hypothesized that reduced serum vitamin D status in NIDDM may be due to reduced expression of megalin and/or its endocytic partners and increased urinary excretion of protein-complexed 25D3. In the present study, we utilized Zucker diabetic fatty Rats (ZDF) to demonstrate that renal reuptake of the 25D3-DBP complex was compromised in ZDF animals, which was reflected by a reduction in expression of megalin and Dab2. Moreover, serum levels of both 25D3and 1,25D3were reduced, and urinary 25D3, 1,25D3, and DBP excretion were elevated in the ZDF animals compared with their lean controls regardless of vitamin D levels in the diet. Taken together, these are the first reports to our knowledge that associate compromised renal reabsorption of the 25D3-DBP complex with expression of megalin and its endocytic partners in NIDDM, which in turn can lead to compromised vitamin D status.
Different effects of oleate vs. palmitate on mitochondrial function, apoptosis, and insulin signaling in L6 skeletal muscle cells: role of oxidative stress
Authors: Yuzefovych Larysa , Wilson Glenn , Rachek Lyudmila
Published: September 2010

The type of free fatty acids (FFAs), saturated or unsaturated, is critical in the development of insulin resistance (IR), since the degree of saturation correlates with IR. We compared the effects of the saturated FFA palmitate, the unsaturated FFA oleate, and a mixture of each on the production of mitochondrial reactive oxygen species (mtROS), mitochondrial DNA (mtDNA) damage, mitochondrial function, apoptosis, and insulin-signaling pathway in skeletal muscle cells. Only palmitate caused a significant increase of mtROS production, which correlated with concomitant mtDNA damage, mitochondrial dysfunction, induction of JNK, apoptosis, and inhibition of insulin signaling. Blocking de novo synthesis of ceramide abolished the effects of palmitate on mtROS production, viability, and insulin signaling. Oleate alone did not cause mtROS generation and mtDNA damage, and its addition to palmitate prevented palmitate-induced mtDNA damage, increased total ATP levels and cell viability, and prevented palmitate-induced apoptosis and inhibition of insulin-stimulated Akt (Ser473) phosphorylation. The peroxisome proliferator activator receptor-γ coactivator 1α (PGC-1α) protein level and promoter activity were decreased at concentrations of palmitate ≥0.5 mM, whereas addition of oleate increased both PGC-1α level and promoter activity. Expression of the mitochondrial transcription factor (TFAM) was significantly diminished after palmitate but not oleate treatment. Addition of the ROS scavenger, N-acetylcystein (NAC), to palmitate restored both the expression and promoter activity of PGC-1α as well as TFAM expression. We propose that 1) mtROS generation is the initial event in the induction of mitochondrial dysfunction and consequent apoptosis and the inhibition of insulin signaling and that 2) oleate ameliorates palmitate-induced mitochondrial dysfunction and thus may contribute to the prevention of palmitate-induced IR.
Aerobic Glycolysis Suppresses p53 Activity to Provide Selective Protection from Apoptosis upon Loss of Growth Signals or Inhibition of BCR-Abl
Authors: Mason Emily F. , Zhao Yuxing , Goraksha-Hicks Pankuri , Coloff Jonathan L. , Gannon Hugh , Jones Stephen N. , Rathmell Jeffrey C.
Published: September 2010

Unlike the growth factor dependence of normal cells, cancer cells can maintain growth factor–independent glycolysis and survival through expression of oncogenic kinases, such as BCR-Abl. Although targeted kinase inhibition can promote cancer cell death, therapeutic resistance develops frequently, and further mechanistic understanding is needed. Cell metabolism may be central to this cell death pathway, as we have shown that growth factor deprivation leads to decreased glycolysis that promotes apoptosis via p53 activation and induction of the proapoptotic protein Puma. Here, we extend these findings to show that elevated glucose metabolism, characteristic of cancer cells, can suppress protein kinase Cδ (PKCδ)–dependent p53 activation to maintain cell survival after growth factor withdrawal. In contrast, DNA damage–induced p53 activation was PKCδ independent and was not metabolically sensitive. Both stresses required p53 Ser18 phosphorylation for maximal activity but led to unique patterns of p53 target gene expression, showing distinct activation and response pathways for p53 that were differentially regulated by metabolism. Consistent with oncogenic kinases acting to replace growth factors, treatment of BCR-Abl–expressing cells with the kinase inhibitor imatinib led to reduced metabolism and p53- and Puma-dependent cell death. Accordingly, maintenance of glucose uptake inhibited p53 activation and promoted imatinib resistance. Furthermore, inhibition of glycolysis enhanced imatinib sensitivity in BCR-Abl–expressing cells with wild-type p53 but had little effect on p53-null cells. These data show that distinct pathways regulate p53 after DNA damage and metabolic stress and that inhibiting glucose metabolism may enhance the efficacy of and overcome resistance to targeted molecular cancer therapies. Cancer Res; 70(20); 8066–76. ©2010 AACR.
Tumor Antigen Acrosin Binding Protein Normalizes Mitotic Spindle Function to Promote Cancer Cell Proliferation
Authors: Whitehurst Angelique W. , Xie Yang , Purinton Scott C. , Cappell Kathryn M. , Swanik Jackie T. , Larson Brittany , Girard Luc , Schorge John O. , White Michael A.
Published: September 2010

Cancer cells manage to divide in the context of gross chromosomal abnormalities. These abnormalities can promote bypass of normal restraints on cell proliferation but at a cost of mitotic vulnerabilities that can be attacked by chemotherapy. Determining how cancer cells balance these issues may permit chemotherapeutic sensitivity to be leveraged more efficiently. From a pan-genomic small interfering RNA screen for modifiers of chemoresponsiveness, we identified the tumor antigen acrosin binding protein (ACRBP)/OY-TES-1 as a specifier of paclitaxel resistance. ACRBP expression is normally restricted to the testes but is detected in a wide variety of cancers, including most ovarian cancers. We found that ACRBP is both necessary and sufficient for paclitaxel resistance in ovarian cancer cell lines and ovarian tumor explants. Moreover, high ACRBP expression correlated with reduced survival time and faster relapse among ovarian cancer patients. We identified the mitotic spindle protein NuMA as an ACRBP-interacting protein that could account for the effects of ACRBP on paclitaxel sensitivity. In cancer cells, ACRBP restricted a NuMA-dependent abrogation of a mitotic spindle assembly that is otherwise pathologic. As a consequence, ACRBP depletion resulted in mitotic errors and reduced proliferative fitness that could be rescued by NuMA codepletion. We propose that the codependent relationship of ACRBP and NuMA in cancer cells reflects their passage through a selection bottleneck during tumor evolution, one which requires the acquisition of traits that normalize mitotic perturbations that originally drove the plasticity of a preneoplastic genome. The molecular definition of such traits as defined by the ACRBP-NuMA complex may represent conceptually ideal intervention targets based on the wide therapeutic windows they may offer. Cancer Res; 70(19); 7652–61. ©2010 AACR.