bluuebunny/crossref_metadata_2025_split huggingface dataset:
A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study
Authors: Greuter M. J. W. , Groen J. M. , Nicolai L. J. , Dijkstra H. , Oudkerk M. 
Published: October 2009

Purpose:The objective of this study is to quantify the influence of linear motion, calcification density, and temporal resolution on coronary calcium determination using multidetector computed tomography (MDCT), dual source CT (DSCT), and electron beam tomography (EBT) and to find a quantitative method which corrects for the influences of these parameters using a linear moving cardiac phantom.Methods:On a robotic arm with artificial arteries with four calcifications of increasing density, a linear movement was applied between 0 and 120 mm/s (step of 10 mm/s). The phantom was scanned five times on 64‐slice MDCT, DSCT, and EBT using a standard acquisition protocol. The average Agatston, volume, and mass scores were determined for each velocity, calcification, and scanner. Susceptibility to motion was quantified using a cardiac motion susceptibility (CMS) index. Resemblance to EBT and physical volume and mass was quantified using a index.Results:Increasing motion artifacts were observed at increasing velocities on all scanners, with increasing severity from EBT to DSCT to 64‐slice MDCT. The calcium score showed a linear dependency on motion from which a correction factor could be derived. This correction factor showed a linear dependency on the mean calcification density with a good fit for all three scoring methods and all three scanners . The slope and offset of this correction factor showed a linear dependency on temporal resolution with a good fit for all three scoring methods and all three scanners . CMS was minimal for EBT and increasing values were observed for DSCT and highest values for 64‐slice MDCT. CMS was minimal for mass score and increasing values were observed for volume score and highest values for Agatston score. For all densities and scoring methods DSCT showed on average the closest resemblance to EBT calcium scores. When using the correction factor, CMS index decreased on average by 15% and index decreased by 35%.Conclusions:Calcium scores determined on DSCT and 64‐slice MDCT are highly susceptible to motion as compared to EBT. The mass score is less susceptible to motion compared to volume and Agatston score. Calcium scores determined on DSCT bear a closer resemblance to EBT obtained calcium scores than 64‐slice MDCT. In addition, the calcium score is highly dependent on the average density of individual calcifications and the dependency of the calcium score on motion showed a linear behavior on calcification density. From these relations, a quantitative method could be derived which corrects the measured calcium score for the influence of linear motion, mean calcification density, and temporal resolution.
Magnetic resonance microwave absorption imaging: Feasibility of signal detection
Authors: Xie Bin , Weaver John B. , Meaney Paul M. , Paulsen Keith D. 
Published: October 2009

Purpose:Magnetic resonance (MR) technique was used to detect small displacements induced by localized absorption of pulsed 434 MHz microwave power as a potential method for tumor detection.Methods:Phase contrast subtraction was used to separate the phase change due to motion from thermoelastic expansion from other contributions to phase variation such as the bulk temperature rise of the medium and phase offsets from the MR scanner itself. A simple set of experiments was performed where the motion was constrained to be one dimensional which provided controls on the data acquisition and motion extraction procedures. Specifically, the MR‐detected motion signal was isolated by altering the direction of the microwave‐induced motion and sampling the response with motion encoding gradients in all three directions when the microwave power was turned on and turned off.Results:Successful signal detection, as evidenced by the recording of a systematic alternating (zigzag) phase pattern, occurred only when the motion encoding was in parallel with either the vertical or horizontal direction of the microwave‐induced motion on both 10 and 4 mm spatial scales.Conclusions:These results demonstrate, for the first time, that motion associated with thermoelastic expansion from the absorption of pulsed microwave power can be detected with MR.
Accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas
Authors: Craciunescu Oana I. , Stauffer Paul R. , Soher Brian J. , Wyatt Cory R. , Arabe Omar , Maccarini Paolo , Das Shiva K. , Cheng Kung‐Shan , Wong Terence Z. , Jones Ellen L. , Dewhirst Mark W. , Vujaskovic Zeljko , MacFall James R. 
Published: October 2009

Purpose:To establish accuracy of real time noninvasive temperature measurements using magnetic resonance thermal imaging in patients treated for high grade extremity soft tissue sarcomas.Methods:Protocol patients with advanced extremity sarcomas were treated with external beam radiation therapy and hyperthermia. Invasive temperature measures were compared to noninvasive magnetic resonance thermal imaging (MRTI) at 1.5 T performed during hyperthermia. Volumetric temperature rise images were obtained using the proton resonance frequency shift (PRFS) technique during heating in a 140 MHz miniannular phased array applicator. MRTI temperature changes were compared to invasive measurements of temperature with a multisensor fiber optic probe inside a #15 g catheter in the tumor. Since the PRFS technique is sensitive to drifts in the primary imaging magnetic field, temperature change distributions were corrected automatically during treatment using temperature‐stable reference materials to characterize field changes in 3D. The authors analyzed MRT images and compared, in evaluable treatments, MR‐derived temperatures to invasive temperatures measured in extremity sarcomas. Small regions of interest (ROIs) were specified near each invasive sensor identified on MR images. Temperature changes in the interstitial sensors were compared to the corresponding ROI PRFS‐based temperature changes over the entire treatment and over the steady‐state period. Nonevaluable treatments (motion/imaging artifacts, noncorrectable drifts) were not included in the analysis.Results:The mean difference between MRTI and interstitial probe measurements was for the entire heating time and for the time at steady state. These values were obtained from both tumor and normal tissue ROIs. When the analysis is done on just the tumor ROIs, the mean difference for the whole power on time was and during the period of steady state was .Conclusions:The data show that for evaluable treatments, excellent correlation of MRTI‐ROI and invasive measurements can be achieved, but that motion and other artifacts are still serious challenges that must be overcome in future work.
A design methodology using signal‐to‐noise ratio for plastic scintillation detectors design and performance optimization
Authors: Lacroix Frédéric , Beddar A. Sam , Guillot Mathieu , Beaulieu Luc , Gingras Luc 
Published: October 2009

Purpose: The design of novel plastic scintillation detectors (PSDs) is impeded by the lack of a suitable framework to simulate and predict their performance. The authors propose to use the signal‐to‐noise ratio (SNR) to model the performance of PSDs that use charge‐coupled devices (CCDs) as photodetectors.Methods: In PSDs using CCDs, the SNR is inversely related to the normalized standard deviation of the dose measurement. Thus, optimizing the SNR directly optimizes the system's precision. In this work, a model of SNR as a function of the system parameters is derived for optical fiber‐based PSD systems. Furthermore, this proposed model is validated using experimental results. A formula for the efficiency of fiber coupling to CCDs is derived and used to simulate the performance of a PSD under varying magnifications.Results: The proposed model is shown to simulate the experimental performance of an actual PSD to a suitable degree of accuracy under various conditions.Conclusions: The SNR constitutes a useful tool to simulate the dosimetric precision of PSDs. Using the SNR model, recommendations for the design and optimization of PSDs are provided. Using the same framework, recommendations for non‐fiber‐based PSDs are also provided.
Projection space denoising with bilateral filtering and CT noise modeling for dose reduction in CT
Authors: Manduca Armando , Yu Lifeng , Trzasko Joshua D. , Khaylova Natalia , Kofler James M. , McCollough Cynthia M. , Fletcher Joel G. 
Published: October 2009

Purpose:To investigate a novel locally adaptive projection space denoising algorithm for low‐dose CT data.Methods:The denoising algorithm is based on bilateral filtering, which smooths values using a weighted average in a local neighborhood, with weights determined according to both spatial proximity and intensity similarity between the center pixel and the neighboring pixels. This filtering is locally adaptive and can preserve important edge information in the sinogram, thus maintaining high spatial resolution. A CT noise model that takes into account the bowtie filter and patient‐specific automatic exposure control effects is also incorporated into the denoising process. The authors evaluated the noise‐resolution properties of bilateral filtering incorporating such a CT noise model in phantom studies and preliminary patient studies with contrast‐enhanced abdominal CT exams.Results:On a thin wire phantom, the noise‐resolution properties were significantly improved with the denoising algorithm compared to commercial reconstruction kernels. The noise‐resolution properties on low‐dose (40 mA s) data after denoising approximated those of conventional reconstructions at twice the dose level. A separate contrast plate phantom showed improved depiction of low‐contrast plates with the denoising algorithm over conventional reconstructions when noise levels were matched. Similar improvement in noise‐resolution properties was found on CT colonography data and on five abdominal low‐energy (80 kV) CT exams. In each abdominal case, a board‐certified subspecialized radiologist rated the denoised 80 kV images markedly superior in image quality compared to the commercially available reconstructions, and denoising improved the image quality to the point where the 80 kV images alone were considered to be of diagnostic quality.Conclusions:The results demonstrate that bilateral filtering incorporating a CT noise model can achieve a significantly better noise‐resolution trade‐off than a series of commercial reconstruction kernels. This improvement in noise‐resolution properties can be used for improving image quality in CT and can be translated into substantial dose reduction.
Identification of Optimal Renal Dosage Adjustments for Traditional and Extended-Infusion Piperacillin-Tazobactam Dosing Regimens in Hospitalized Patients
Authors: Patel N. , Scheetz M. H. , Drusano G. L. , Lodise T. P. 
Published: October 2009

ABSTRACTThis study examined the effect of various levels of renal impairment on the probability of achieving free drug concentrations that exceed the MIC for 50% of the dosing interval (50%fT > MIC) for traditional and extended-infusion piperacillin-tazobactam (TZP) dosing strategies. It also identified optimal renal dosage adjustments for traditional and extended-infusion dosing schemes that yielded probability of target attainment (PTA) and exposure profiles that were isometric to those of the parent regimens. Data from 105 patients were analyzed using the population pharmacokinetic modeling program BigNPAG. To assess the effect of creatinine clearance (CLCR) on overall clearance, TZP clearance was made proportional to the estimated CLCR. A Monte Carlo simulation (9,999 subjects) was performed for the traditional dosing scheme (4.5 g infused during 30 min every 6 h) and the extended-infusion TZP dosing scheme (3.375 g infused during 4 h every 8 h). The fraction of simulated subjects who achieved 50%fT > MIC was calculated for the range of piperacillin MICs from 0.25 to 32 mg/liter and stratified by CLCR. The traditional TZP regimen displayed the greatest variability in PTA across MIC values, especially for MIC values exceeding 4 mg/liter, when stratified by CLCR. In contrast, the PTA for the extended-infusion TZP regimen exceeded ≥80% for MIC values of ≤8 mg/liter across all CLCRstrata. All regimens were associated with suboptimal PTA for MIC values of ≥32 mg/liter irrespective of the CLCR. The CLCRadjustments for traditional and extended-infusion TZP dosing regimens should be considered at a CLCRof ≤20 ml/min.
Pharmacometrics-Based Dose Selection of Levofloxacin as a Treatment for Postexposure Inhalational Anthrax in Children
Authors: Li Fang , Nandy Partha , Chien Shuchean , Noel Gary J. , Tornoe Christoffer W. 
Published: October 2009

ABSTRACT
Levofloxacin was recently (May 2008) approved by the U.S. Food and Drug Administration as a treatment for children following inhalational exposure to anthrax. Given that no clinical trials to assess the efficacy of a chosen dose was conducted, the basis for the dose recommendation was based upon pharmacometric analyses. The objective of this paper is to describe the basis of the chosen pediatric dose recommended for the label. Pharmacokinetic (PK) data from 90 pediatric patients receiving 7 mg/kg of body weight levofloxacin and two studies of 47 healthy adults receiving 500 and 750 mg/kg levofloxacin were used for the pharmacometric analyses. Body weight was found to be a significant covariate for levofloxacin clearance and the volume of distribution. Consistently with developmental physiology, clearance also was found to be reduced in pediatric patients under 2 years of age due to immature renal function. Different dosing regimens were simulated to match adult exposure (area under the concentration-time curve from 0 to 24 h at steady state, maximum concentration of drug in serum at steady state, and minimum concentration of drug in serum at steady state) following the approved adult dose of 500 mg once a day. The recommended dose of 8 mg/kg twice a day was found to match the exposure of the dose approved for adults in a manner that permitted confidence that this dose in children would achieve efficacy comparable to that of adults.
A Single Mutation in Enzyme I of the Sugar Phosphotransferase System Confers Penicillin Tolerance to
Streptococcus gordonii
Authors: Bizzini A. , Entenza J. M. , Michielin O. , Arnold I. , Erni B. , Moreillon P. 
Published: October 2009

ABSTRACT

Tolerance is a poorly understood phenomenon that allows bacteria exposed to a bactericidal antibiotic to stop their growth and withstand drug-induced killing. This survival ability has been implicated in antibiotic treatment failures. Here, we describe a single nucleotide mutation (
tol1
) in a tolerant
Streptococcus gordonii
strain (Tol1) that is sufficient to provide tolerance in vitro and in vivo. It induces a proline-to-arginine substitution (P483R) in the homodimerization interface of enzyme I of the sugar phosphotransferase system, resulting in diminished sugar uptake. In vitro, the susceptible wild-type (WT) and Tol1 cultures lost 4.5 and 0.6 log
10
CFU/ml, respectively, after 24 h of penicillin exposure. The introduction of
tol1
into the WT (WT P483R) conferred tolerance (a loss of 0.7 log
10
CFU/ml/24 h), whereas restitution of the parent sequence in Tol1 (Tol1 R483P) restored antibiotic susceptibility. Moreover, penicillin treatment of rats in an experimental model of endocarditis showed a complete inversion in the outcome, with a failure of therapy in rats infected with WT P483R and the complete disappearance of bacteria in animals infected with Tol1 R483P.
Antifungal Activity of Colistin against
Mucorales
Species
In Vitro
and in a Murine Model of
Rhizopus oryzae
Pulmonary Infection
Authors: Ben-Ami Ronen , Lewis Russell E. , Tarrand Jeffrey , Leventakos Konstantinos , Kontoyiannis Dimitrios P. 
Published: October 2009

ABSTRACT

In immunosuppressed hosts, mucormycosis is a life-threatening infection with few treatment options. We studied the activity of colistin (polymyxin E) against
Mucorales
species
in vitro
and in a murine model of pulmonary
Rhizopus oryzae
infection. Colistin exhibited fungicidal activity
in vitro
against
Mucorales
spores and mycelia. At the colistin MIC, initial
R. oryzae
hyphal damage was followed by rapid regrowth; however, regrowth was prevented by combining colistin with a subinhibitory concentration of amphotericin B. Using electron microscopy and FM4-64 staining, we demonstrated that colistin disrupts
R. oryzae
cytoplasmic and vacuolar membranes, resulting in the leakage of intracellular contents. The prophylactic intranasal treatment of immunosuppressed mice with colistimethate significantly reduced the mortality rate and pulmonary fungal burden resulting from inhalational challenge with
R. oryzae
spores, whereas intraperitoneal colistimethate treatment had no effect. We conclude that colistin has modest
in vitro
and
in vivo
fungicidal activity against
Mucorales
spp. Further studies are warranted to assess the use of this drug in the prevention and treatment of mucormycosis.
Inhibition of B Virus (Macacine herpesvirus1) by Conventional and Experimental Antiviral Compounds
Authors: Krug P. W. , Schinazi R. F. , Hilliard J. K. 
Published: October 2009

ABSTRACTB virus infection of humans results in high morbidity and mortality in as many as 80% of identified cases. The main objective of this study was to conduct a comparative analysis of conventional and experimental antiviral drug susceptibilities of B virus isolates from multiple macaque species and zoonotically infected humans. We used a plaque reduction assay to establish the effective inhibitory doses of acyclovir, ganciclovir, and vidarabine, as well as those of a group of experimental nucleoside analogs with known anti-herpes simplex virus activity. Four of the experimental drugs tested were 10- to 100-fold more potent inhibitors of B virus replication than conventional antiviral agents. Drug efficacies were similar for multiple B virus isolates tested, with variations within 2-fold of the median effective concentration (EC50) for each drug, and each EC50was considerably lower than those for B virus thymidine kinase (TK) mutants. We observed no differences in the viral TK amino acid sequence between B virus isolates from rhesus monkeys and those from human zoonoses. Differences in the TK protein sequence between cynomolgus and pigtail macaque B virus isolates did not affect drug sensitivity except in the case of one compound. Taken together, these data suggest that future B virus zoonoses will respond consistently to conventional antiviral treatment. Further, the considerably higher potency of FEAU (2′-fluoro-5-ethyl-Ara-U) than of conventional antiviral drugs argues for its compassionate use in advanced human B virus infections.
Division of theSalmonella-Containing Vacuole and Depletion of Acidic Lysosomes inSalmonella-Infected Host Cells Are Novel Strategies ofSalmonella entericaTo Avoid Lysosomes
Authors: Eswarappa Sandeepa M. , Negi Vidya Devi , Chakraborty Sangeeta , Chandrasekhar Sagar B. K. , Chakravortty Dipshikha 
Published: October 2009

ABSTRACTSalmonellahas evolved several strategies to counteract intracellular microbicidal agents like reactive oxygen and nitrogen species. However, it is not yet clear howSalmonellaescapes lysosomal degradation. Some studies have demonstrated thatSalmonellacan inhibit phagolysosomal fusion, whereas other reports have shown that theSalmonella-containing vacuole (SCV) fuses/interacts with lysosomes. Here, we have addressed this issue from a different perspective by investigating if the infected host cell has a sufficient quantity of lysosomes to targetSalmonella. Our results suggest that SCVs divide along withSalmonella, resulting in a single bacterium per SCV. As a consequence, the SCV load per cell increases with the division ofSalmonellainside the host cell. This demands more investment from the host cell to counteractSalmonella. Interestingly, we observed thatSalmonellainfection decreases the number of acidic lysosomes inside the host cell bothin vitroandin vivo. These events potentially result in a condition in which an infected cell is left with insufficient acidic lysosomes to target the increasing number of SCVs, which favors the survival and proliferation ofSalmonellainside the host cell.
Use of an elastic stain to show venous invasion in colorectal carcinoma: a simple technique for detection of an important prognostic factor
Authors: Howlett C J , Tweedie E J , Driman D K 
Published: October 2009

Background:Venous invasion (VI) is an important prognostic factor in colorectal cancer; it is positively associated with visceral metastases and may affect the decision to treat with adjuvant therapy.Aims:To evaluate whether an elastic tissue (Movat) stain facilitates identification of VI, the number of Movat-stained blocks needed to detect VI, and whether VI identified with a Movat stain is prognostically equivalent to VI identified on H&E-stained slides.Methods:H&E-stained sections from colorectal carcinomas from the year 2000 (n = 92) were examined for VI and compared to Movat-stained slides. Clinical charts were reviewed to compare rates of metastases in VI-positive versus VI-negative patients.Results:With the Movat stain, VI was identified in 44% of cases previously categorised as negative (p<0.001) on review of H&E slides alone. One Movat-stained section was often sufficient to identify VI, with a statistically significant benefit to performing multiple stains if necessary. In H&E sections, two clues helped identify VI: the “unaccompanied artery” sign, where large arteries were seen without an accompanying vein; and the “protruding tongue” sign, where smooth tongues of tumour extended into pericolic/rectal fat. Metastases were present in 61% of cases positive for VI compared to 35% in VI-negative cases (p = 0.03). 45% of cases positive for intramural VI only developed metastases (p = 0.39), while 65% of cases positive for extramural VI only developed metastases (p = 0.03).Conclusions:Pathologists should look for morphological clues of VI in H&E stained sections; when VI is not apparent, an elastic tissue stain on all tumour blocks significantly improves identification of VI. Morphological clues include the “unaccompanied artery” and “protruding tongue” signs.