bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and validation of an LC‐MS/MS method for quantifying nine antimicrobials in human serum and its application to study the exposure of Chinese pregnant women to antimicrobials
Authors: Li Youran , Yue Xiaofei , Pan Zhifeng , Liu Ying , Shen Min , Zhai Yanhong , Cao Zheng
Published: November 2020

Background

To study the prevalence of the exposure of pregnant women to antimicrobials, a sensitive and reliable liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method was developed and validated to determine nine antimicrobials, namely sulfadimidine, sulfapyridine, sulfadiazine, sulfathiazole, ofloxacin, ciprofloxacin, norfloxacin, tetracycline, and lincomycin, in human serum.

Methods

The sample preparation procedure included protein precipitation followed by a cleanup step with solid phase extraction (SPE). Separation was carried out using a CORTECS T3 column (100 × 2.1 mm, 2.7 µm) by gradient elution with a runtime of 8.0 min. Detection was performed on a triple quadruple tandem mass spectrometer with scheduled multiple reaction monitoring (sMRM) in positive ion scan mode.

Results

The calibration curves were linear over the concentration range of 0.5–50 ng/ml, and the limit of quantitation was between 0.01 and 0.2 ng/ml. For each level of quality control samples, the inter‐ and intra‐assay precision values were less than 12.0%, and the accuracy ranged from 86.1% to 109.0%. No significant matrix effect or carryover was observed. The antimicrobials of interest were stable under all investigated conditions. The validated method was applied to analyze clinical samples from pregnant women in China, and 10 out of 500 samples showed the presence of antimicrobial residues. Moreover, compared with the time‐resolved fluoro‐immunoassay (TRFIA) method, the developed method showed greater sensitivity and specificity.

Conclusion

This study provides a simple and rapid LC‐MS/MS method for the simultaneous measurement of nine antimicrobials in serum samples, which could be a useful tool in clinical utilization.
Antibody‐dependent enhancement (ADE) of dengue virus: Identification of the key amino acid that is vital in DENV vaccine research
Authors: Cui Guohui , Si Lulu , Wang Ying , Zhou Junmei , Yan Huijun , Jiang Lifang
Published: November 2020

Background

The antibody‐dependent enhancement (ADE) of dengue virus (DENV) has critically restricted vaccine development. Prior research suggested pr4 as the probable ADE epitope of DENV.

Methods

Chimeric DENV was constructed by replacing the DENV pr4 gene with the corresponding Japanese encephalitis virus (JEV) gene to determine whether it can reduce ADE activities. An alanine scanning method and bioinformatics analysis were utilized to identify the amino acid of pr4 that was crucial as an ADE epitope.

Results

Chimeric virus reduced ADE and virulence. The amino acids at the following locations on the mutant peptides showed significantly reduced binding ability to prM antibody: pr4.5 (position 5 – leucine), pr4.6 (position 6 – leucine), pr4.7 (position 7 – phenyalanine) and pr4.16 (position 16 – cysteine). The four amino acids had formed a pocket‐like structure, which could increase the possibility of binding to an antibody.

Conclusions

ADE activities could be reduced by replacing the DENV pr4 gene with the corresponding JEV gene. Leucine at position 5, leucine at position 6, phenyalanine at position 7 and cysteine at position 16 were the key amino acid sites in the ADE response of DENV. The occurrence of ADE can potentially be reduced by the replacement of key amino acids, hence highlighting its possible contribution to dengue vaccine design, paving a way for future vaccine research.
Bilateral subdural hematomas and retinal hemorrhages mimicking nonaccidental trauma in a patient with D‐2‐hydroxyglutaric aciduria
Authors: Perales‐Clemente Ester , Hewitt Angela L. , Studinski April L. , Tillema Jan‐Mendelt , Laxen William J. , Oglesbee Devin , Graff Arne H. , Rinaldo Piero , Lanpher Brendan C.
Published: November 2020

Introduction

Nonaccidental trauma (NAT) is considered when pediatric patients present with intracranial injuries and a negative history of an accidental injury or concomitant medical diagnosis. The evaluation of NAT should include the consideration of possible medical causes including coagulation, hematologic, metabolic and other genetic disorders, as well as witnessed and unwitnessed accidental injuries.

Case Presentation

We present a 7‐month‐old male with spells and incidental findings of bilateral subdural hematomas, retinal hemorrhages, and secondary macrocephaly, leading to investigation for NAT. Biochemical analysis showed excretion of a large amount of D‐2‐hydroxyglutaric in urine consistent with a biochemical diagnosis of D‐2‐hydroxyglutaric aciduria, a rare neurometabolic disorder characterized by developmental delay, epilepsy, hypotonia, and psychomotor retardation. None of these symptoms were present in our patient at the time of diagnosis. Molecular genetic testing revealed a pathogenic splice site variant (c.685‐2A>G) and a variant of uncertain significance (c.1256G>T) with evidence of pathogenicity in the D2HGDH gene, consistent with a molecular diagnosis of D‐2‐hydroxyglutaric aciduria type I (OMIM #600721).

Conclusion

Since several metabolic disorders, including D‐2‐hydroxyglutaric aciduria type I, can present solely with symptoms suggestive of NAT (subdural and retinal hemorrhages), an early metabolic evaluation by urine organic acid analysis should be included in clinical protocols evaluating NAT. A methodical and nonjudgmental approach coordinated between pediatricians and metabolic specialists is also necessary to ensure that rare genetic conditions are not overlooked to prevent devastating social, legal, and financial consequences of suspected child abuse.
Clinical characteristics of pediatric SARS‐CoV‐2 infection and coronavirus disease 2019 (COVID‐19) in Kuwait
Authors: Alsharrah Danah , Alhaddad Fatemah , Alyaseen Munirah , Aljamaan Sarah , Almutairi Nahar , Ayed Mariam , Papenburg Jesse , Alghounaim Mohammad
Published: November 2020

Clinical presentation of coronavirus disease‐2019 (COVID‐19) ranges from asymptomatic to severe and life‐threatening. National‐level registries found that children, generally, have less severe disease when compared with adults. However, most asymptomatically infected children will not present to hospital and may be missed. We aimed to describe the clinical characteristics in pediatric COVID‐19 patients in Kuwait, and to estimate the potential duration of viral shedding. A retrospective cohort study was performed in Jaber Alahmad Hospital (JAH) from February 29 to April 30, 2020. During the study period and as part of the public health measures, all severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐infected patients from 1 month to 18 years old, regardless of symptoms, were hospitalized at JAH, and were included. Polymerase chain reaction (PCR) negativity was defined as having two consecutive negative PCR results from a respiratory specimen. Descriptive statistics and multivariable regression analyses were performed. We found that 67.9% (95% CI, 59.4%–75.3%) of 134 SARS‐CoV‐2‐infected children were asymptomatic. Median PCR positivity was 15 days and did not vary with symptoms. Among patients who had laboratory investigations and chest imaging, symptomatic infection was associated with elevated C‐reactive protein and procalcitonin, and radiographic pneumonia. Asymptomatic SARS‐CoV‐2 infection is very common in children. Among symptomatic patients, the disease seems to be mild. Children exhibit substantial duration of viral shedding, regardless of symptoms.
Reporting of test comparisons in diagnostic accuracy studies: A literature review
Authors: Vali Yasaman , Yang Bada , Olsen Maria , Leeflang Mariska M. G. , Bossuyt Patrick M. M.
Published: November 2020

Comparative accuracy studies evaluate the relative performance of two or more diagnostic tests. As any other form of research, such studies should be reported in an informative manner, to allow replication and to be useful for decision‐making. In this study we aimed to assess whether and how components of test comparisons were reported in comparative accuracy studies. We evaluated 100 comparative accuracy studies, published in 2015, 2016 or 2017, randomly sampled from 238 comparative accuracy systematic reviews. We extracted information on 20 reporting items, pertaining to the identification of the test comparison, its validity, and the actual results of the comparison. About a third of the studies (n = 36) did not report the comparison as a study objective or hypothesis. Although most studies (n = 86) reported how participants had been allocated to index tests, we could often not evaluate whether test interpreters had been blinded to the results of other index tests (n = 40; among 59 applicable studies), nor could we identify the sequence of index tests (n = 52; among 90 applicable studies) or the methods for comparing measures of accuracy (n = 59). Two‐by‐four table data (revealing the agreement between index tests) were only reported by 9 of 90 paired comparative studies. More than half of the studies (n = 64) did not provide measures of statistical imprecision for comparative accuracy. Our findings suggest that components of test comparisons are frequently missing or incompletely described in comparative accuracy studies included in systematic reviews. Explicit guidance for reporting comparative accuracy studies may facilitate the production of full and informative study reports.
Chronic Posttraumatic Stress Disorder and Comorbid Cognitive and Physical Impairments in World Trade Center Responders
Authors: Diminich Erica D. , Clouston Sean A. P. , Kranidis Alexandra , Kritikos Minos , Kotov Roman , Kuan Peifen , Carr Melissa , Bromet Evelyn J. , Luft Benjamin J.
Published: November 2020

Posttraumatic stress disorder (PTSD) has been linked to increased prevalence and incidence of cognitive and physical impairment. When comorbid, these conditions may be associated with poor long‐term outcomes. We examined associations between chronic PTSD and symptom domains with cognitive and physical functioning in World Trade Center (WTC) responders nearly 20 years after the September 11, 2001, terrorist attacks. Participants included a cross‐sectional sample of 4,815 responders who attended a monitoring program in 2015–2018. Montreal Cognitive Assessment scores less than 23 indicated cognitive impairment (CogI); Short Physical Performance Battery scores 9 or lower on a hand‐grip test indicated physical impairment (PhysI). Comorbid cognitive/physical impairment (Cog/PhysI) was defined as having cognitive impairment with at least one objective PhysI indicator. Clinical chart review provided PTSD diagnoses; symptom domains were assessed using the PTSD Checklist. Participants were on average 53.05 years (SD = 8.01); 13.44% had PTSD, 7.8% had CogI, 24.8% had PhysI, and 5.92% had comorbid Cog/PhysI. Multivariable‐adjusted multinomial logistic regression demonstrated that Responders with PTSD have more than three times the risk of Cog/PhysI (adjusted RR = 3.29, 95% CI 2.44‐ 4.44). Domain‐specific analyses revealed that emotional numbing symptoms predicted an increased risk of PhysI (adjusted RR = 1.57, 95% CI 1.08‐2.28), whereas reexperiencing symptoms were associated with comorbid Cog/PhysI (adjusted RR = 3.96, 95% CI, 2.33‐6.74). These results suggest that responders with chronic PTSD may have increased risk of deficits beyond age‐expected impairment characterized by the emergence of comorbid Cog/PhysI at midlife.
Prevalence of Olfactory Dysfunction in Coronavirus Disease 2019 (COVID‐19): A Meta‐analysis of 27,492 Patients
Authors: Saniasiaya Jeyasakthy , Islam Md Asiful , Abdullah Baharudin
Published: November 2020

Objectives/Hypothesis

Olfactory dysfunction has been observed as one of the clinical manifestations in COVID‐19 patients. We aimed to conduct a systematic review and meta‐analysis to estimate the overall pooled prevalence of olfactory dysfunction in COVID‐19 patients.

Study Design

Systematic review and meta‐analyses.

Methods

PubMed, Scopus, Web of Science, Embase, and Google Scholar databases were searched to identify studies published between 1 December 2019 and 23 July 2020. We used random‐effects model to estimate the pooled prevalence with 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 statistic and Cochran's Q test. Robustness of the pooled estimates was checked by different subgroup and sensitivity analyses This study is registered with PROSPERO (CRD42020183768).

Results

We identified 1162 studies, of which 83 studies (n = 27492, 61.4% female) were included in the meta‐analysis. Overall, the pooled prevalence of olfactory dysfunction in COVID‐19 patients was 47.85% [95% CI: 41.20–54.50]. We observed olfactory dysfunction in 54.40% European, 51.11% North American, 31.39% Asian, and 10.71% Australian COVID‐19 patients. Anosmia, hyposmia, and dysosmia were observed in 35.39%, 36.15%, and 2.53% of the patients, respectively. There were discrepancies in the results of studies with objective (higher prevalence) versus subjective (lower prevalence) evaluations. The discrepancy might be due to false‐negative reporting observed in self‐reported health measures.

Conclusions

The prevalence of olfactory dysfunction in COVID‐19 patients was found to be 47.85% based on high‐quality evidence. Due to the subjective measures of most studies pooled in the analysis, further studies with objective measures are advocated to confirm the finding.

Level of Evidence

2 Laryngoscope, 131:865–878, 2021
Responses of plant, soil bacterial and fungal communities to grazing vary with pasture seasons and grassland types, northern Tibet
Authors: Zhang Haorui , Fu Gang
Published: November 2020

Synthetic responses of plant and soil microbial communities to grazing are indefinite in alpine grasslands on the Tibetan Plateau. Three paired, fenced and free grazing sites (alpine steppe meadow for winter pasture [ASMWP]; alpine steppe meadow for summer pasture [ASMSP]; alpine meadow for summer pasture [AMSP]) were used to compare how pasture season and grassland type affect responses of the α‐diversity and community composition of plant, soil bacteria and fungi to grazing. Cold‐season grazing reduced soil moisture by 12.10%, ammonium nitrogen (NH4+‐N) by 53.71%, the ratio of available nitrogen to phosphorus by 64.11%, species richness (SR) by 31.4% and the Shannon by 11.9% of plant community on the ASMWP. Warm‐season grazing reduced nitrate nitrogen by 30.45%, SR of soil bacterial community by 21.98% on the ASMSP, but increased soil NH4+‐N by 90.02% on the AMSP. Warm‐season grazing‐induced changes in plant community composition were mainly related to the composition of forbs on the AMSP. Grazing‐induced changes in the community composition of soil bacteria were mainly related to Proteobacteria, Acidobacteria, Bacteroidetes, Firmicutes and Verrucomicrobia on the ASMWP, and Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi and TM7 on the ASMSP. Grazing‐induced changes in the community composition of soil fungi were mainly related to Ascomycota and Basidiomycota on the ASMWP, Basidiomycota on the ASMSP and Ascomycota on the AMSP. Therefore, the effects of grazing on plant and soil microbial communities may vary with grassland types and pasture seasons, which may be related to grazing‐induced changes in available nitrogen, the ratio of available nitrogen to phosphorus and soil moisture.
The potential role of turbulence in modulating the migration of demersal zooplankton
Authors: Tanaka Mamoru , Genin Amatzia , Endo Yoshinari , Ivey Gregory N. , Yamazaki Hidekatsu
Published: November 2020

Despite suggestions that turbulence can affect the migration of zooplankton, field observations of such effects are scarce. This is especially the case for bottom‐associated (demersal) zooplankton that reside in the typically turbulent near‐bottom environment. Using moored sensors deployed at two coastal sites in the North Pacific and the Red Sea, we present observations of the effects of turbulence on the nocturnal emergence of demersal zooplankton. A cabled observatory consisting of a plankton camera, an acoustic current profiler and environmental sensors, was deployed near bottom in 20 m of water near Oshima Island, Japan. Observations were also obtained from a second site near a coral reef in 16 m of water in the Red Sea. Acoustic backscatter data obtained from current profilers at both sites provided a proxy for zooplankton density. Combined with simultaneous estimates of turbulence intensity, the observations suggest that the nocturnal emergence of demersal zooplankton was hindered by elevated levels of turbulence. While our findings are inferred from acoustic data, agreement between the two different sites supports our hypothesis that demersal zooplankton may remain near the bed during times of strong turbulence.
Biodegradable oxygen biosensors via electrospinning
Authors: Cybyk Daniel B. , Reinsch Bonnie M. , Presley Kayla F. , Schweller Ryan M. , Tedeschi Andrea , Burns Teresa , Chaparro Francisco J. , Ly Jack T. , Dalton Matthew J. , Lozano Monica , Grusenmeyer Tod A. , Lannutti John J.
Published: November 2020

Monitoring oxygenation in vivo is critical to ensuring human health, particularly in the context of ‘silent’ hypoxia. Utilizing blends of biodegradable polycaprolactone (PCL) and gelatine, we sought to develop an electrospun oxygen sensor that maintains the advantages of robust, phosphorescent oxygen‐sensing chromophores while providing resorbable polymeric scaffolds benefiting from tailorable degradation times ranging from hours to weeks. Electrospun sensors successfully provide accurate oxygen measurements for periods >1 month. In vitro testing took place in a custom aqueous testing system over five weeks in 37°C phosphate‐buffered saline (PBS); dissolved oxygen concentrations were maintained at 0–5% O2 where physoxia characteristic of the subdermal environment is defined as 2–5% O2. Excited state chromophore lifetime (τ) is quenched in the presence of dissolved diatomic oxygen and is influenced by characteristics of the surrounding matrix. The observed final deoxygenated τ (τ0) values were split into 3 groups: polysulphone (PSU)‐PCL (~397 µs) >75:25, 50:50 and 25:75 PCL:gelatine (~191–182 µs) > PCL, 10:90 PCL:gelatine, 1:99 crosslinked PCL:gelatine (~145–135 µs). Highly linear Stern–Volmer activity enabling accurate and precise calibration was observed even after 35 days of exposure; this proves that non‐core–shell fibres consisting of blends of PCL and gelatine can yield predictable lifetime values for >30 days in vitro. Scanning electron microscopy and mass loss data revealed that sensor degradation is highly tailorable, allowing for the fabrication of sensors engineered for a specific biomedical time frame. In contrast, core–shell fibre sensors showed more variability in lifetime following internal degradation likely caused by caproic acid entrapment by the PCL ‘shell’. This work demonstrates that biodegradable and biocompatible optically monitored sensors can be fabricated to provide direct, accurate assessments of oxygenation, even as the sensor platform degrades in a controlled manner. Such technologies have the potential to substantially change respiratory disease management.
NYC pilot to respond to MH crises needs peer de‐escalators, advocates say
Authors: Canady Valerie A.
Published: November 2020

A New York City pilot proposal to include emergency medical services (EMS) and mental health crisis workers to be dispatched through 911 to respond to mental health emergencies has raised concerns among advocates who say the effort does not go far enough and does not take the responsibility for handling mental health crisis calls away from police.
Single pencil beam benchmark of a module for Monte Carlo simulation of proton transport in the PENELOPE code
Authors: Verbeek Nico , Wulff Jörg , Bäumer Christian , Smyczek Sabrina , Timmermann Beate , Brualla Lorenzo
Published: November 2020

Background and purpose

PENH is a recently coded module for simulation of proton transport in conjunction with the Monte Carlo code PENELOPE. PENELOPE applies class II simulation to all type of interactions, in particular, to elastic collisions. PENH uses calculated differential cross sections for proton elastic collisions that include electron screening effects as well as nuclear structure effects. Proton‐induced nuclear reactions are simulated from information in the ENDF‐6 database or from alternative nuclear databases in ENDF format. The purpose of this work is to benchmark this module by simulating absorbed dose distributions from a single finite spot size proton pencil beam in water.

Materials and methods

Monte Carlo simulations with PENH are compared with simulation results from TOPAS Monte Carlo (v3.1p2) and RayStation Monte Carlo (v6). Different beam models are examined in terms of mean energy and energy spread to match the measured profiles. The phase‐space file is derived from experimental measurements. Simulated absorbed dose distributions are compared to experimental data obtained with the ionization chamber array MatriXX 2D detector (IBA Dosimetry) in a water tank. The experiments were conducted with a clinical IBA pencil beam scanning dedicated nozzle. In all simulations a Fermi‐Eyges phase‐space representation of a single finite spot size proton pencil beam is used.

Results

In general, there is a good agreement between simulated results and experimental data up to a distance of 3 cm from the central axis. In the core region (region where the dose is more than 10% of the maximum dose) PENH shows, overall, the smallest deviations from experimental data, with the largest radial rms (root mean square) smaller than 0.2. The results achieved by TOPAS and RayStation in that region are very close to those of PENH. For the halo region, that is the area of the dose distribution outside the core region reaching down to 0.01% of the maximum intensity, the largest rms achieved by TOPAS is always smaller than 0.5, yielding better results than the rest of the codes.

Conclusion

The physics modeling of the PENELOPE/PENH code yields results consistent with measurements in the dose range relevant for proton therapy. The discrepancies between PENH appearing at distances larger than 3 cm from the central‐beam axis are accountable to the lack of neutron simulation in this code. In contradistinction, TOPAS has a better agreement with experimental data at large distances from the central‐beam axis because of the simulation of neutrons.
Imaging of polarized components of Cerenkov light and luminescence of water during carbon‐ion irradiation
Authors: Yamamoto Seiichi , Yabe Takuya , Akagi Takashi , Hirano Yoshiyuki
Published: November 2020

Purpose

The luminescence image of water during the irradiation of carbon ions showed higher intensity at shallow depths than dose distribution due to the contamination of Cerenkov light from secondary electrons. Since Cerenkov light is coherent and polarized for the light produced during the irradiation of carbon ions to water, the reduction of Cerenkov light may be possible with a polarizer. In addition, there is no information on the polarization of the luminescence of water. To clarify these points, we measured the optical images of water during the irradiation of carbon ions with a polarizer by changing the directions of the transmission axis.

Methods

Imaging was conducted using a cooled charge‐coupled device (CCD) camera during the irradiation of 241.5 MeV/n energy carbon ions to a water phantom with a polarizer in front of the lens by changing the transmission axis parallel and perpendicular to the carbon‐ion beam.

Results

With the polarizer parallel to the carbon‐ion beam, the intensity at the shallow depth was ~26% higher than that measured with the polarizer perpendicular to the beam. We found no significant intensity difference between these two images at deeper depths where the Cerenkov light was not included. The difference image of the parallel and perpendicular directions showed almost the same image as the simulated Cerenkov light distribution. Using the measured difference image, correction of the Cerenkov component was possible from the measured luminescence image of water during the irradiation of carbon ions.

Conclusion

We could measure the difference of the Cerenkov light component by changing the transmission axis of the polarizer. Also we clarified that there was no difference in the luminescence of water by changing the transmission axis of the polarizer.
Internal dosimetry of [99mTc]NTP15‐5 radiotracer for cartilage imaging in preclinical and clinical models using the GATE Monte Carlo platform
Authors: Fois Giovanna Rosa , Valla Clémence , Jouberton Elodie , Sas Nicolas , Billoux Tommy , Auzeloux Philippe , Cachin Florent , Miot‐Noirault Elisabeth , Maigne Lydia
Published: November 2020

Purpose

This study aims to perform dosimetry for [99mTc]NTP15‐5 radiotracer used in imaging of articular cartilage in rabbits and humans. The radiotracer (covered by a world patent WO 01/00621 A1) has been proposed in the previous years for the study of cartilage in osteoarthritis diseases. A sensitive imaging approach is essential to quantify osteoarthritis progression and monitor response to new therapies. [99mTc]NTP15‐5 binds to cartilage proteoglycans whose decreased content is associated to a loss of biomedical function of cartilage. We have implemented the whole dosimetry study concerning this new radiotracer for rabbits and humans using the GATE Monte Carlo platform.

Materials and methods

Absorbed doses to critical organs are determined using the MIRD formalism. Biodistribution data are obtained by organ sampling, measuring the activity in organs for three rabbits sacrificed at various times postadministration, and by SPECT/CT imaging at different times after injection. Most important sources are cartilages (in knees and intervertebral discs), due to localization together with the liver and kidneys due to excretion of the agent. S‐values are calculated from rabbit’s CT scan and human CT scan using the GATE v8.0 Monte Carlo platform. Cumulated activity in humans is extrapolated from animals using the %kg‐dose/g method. Particular attention is given to dose calculation in bones, bone marrow and organs at risk.

Results

The dosimetry performed in rabbits shows highest absorbed doses for liver and kidneys with respectively 22.5 and 43.8 µGy per MBq of injected activity. In humans, we found absorbed doses for a maximum injected activity of 15 MBq/kg, that is, 1050 MBq for an adult of 70 kgs of 9.03 mGy for kidneys and 4.16 mGy for knee cartilages. Effective dose is 2.69 µSv/MBq.

Conclusions

The dosimetry profile of [99mTc]NTP15‐5 in the context of preclinical trials is of major importance in order to make sure that organs at risk are not overexposed. GATE provides all the capability needed to calculate dose profiles for internal dosimetry. The extrapolation of the dose for a human model is a first step towards clinical trials.
Source position measurement by Cherenkov emission imaging from applicators for high‐dose‐rate brachytherapy
Authors: Yogo Katsunori , Noguchi Yumiko , Okudaira Kuniyasu , Nozawa Marika , Ishiyama Hiromichi , Okamoto Hiroyuki , Yasuda Hiroshi , Oguchi Hiroshi , Yamamoto Seiichi
Published: November 2020

Purpose

We developed a novel and simple method to measure the source positions in applicators directly for high‐dose‐rate (HDR) brachytherapy based on Cherenkov emission imaging, and evaluated the performance.

Methods

The light emission from plastic applicators used in cervical cancer treatments, irradiated by an 192Ir γ‐ray source, was captured using a charge‐coupled device camera. Moreover, we attached plastics of different shapes, including tapes, tubes, and plates to a metal applicator, to use as screens for the Cherenkov imaging. We determined the source positions and dwell intervals from the light profiles along with the applicator and compared these with preset values and dummy marker measurements.

Results

The source positions and dwell intervals measured from the light images were comparable to the dummy marker measurements and preset values. The distance from the applicator tip to the first source positions agreed with the dummy marker measurements within 0.2 mm for the plastic tandem. The dwell intervals measured using the Cherenkov method agreed with the preset values within 0.6 mm. The distances measured with three plastic types on the metal applicator also agreed with the dummy marker measurements within 0.2 mm. The dwell intervals measured using the plastic tape agreed with the preset values within 0.7 mm.

Conclusions

The proposed method should be suitable for rapid and easy quality assurance (QA) investigations in HDR brachytherapy, as it enables source position using a single image. The method allows for real‐time, filmless measurements of the source positions to be obtained and is useful for rapid feedback in QA procedures.
Performance of a multileaf collimator system for a 1.5T MR‐linac
Authors: Zhang Ke , Tian Yuan , Li Minghui , Men Kuo , Dai Jianrong
Published: November 2020

Purpose

The purpose of this study was to evaluate the performance of a multileaf collimator (MLC) system for the high magnetic field of the Elekta Unity magnetic resonance linear accelerator (MR‐linac).

Methods

Performance was evaluated as recommended in AAPM Report Nos. 72 and 142, and MLC motor radiofrequency (RF) shielding was also evaluated. Fields of 99.8 × 99.8 mm2 and 199.6 × 199.6 mm2 were examined to calculate the leaf width. Profiles of 28.4 × 28.4 mm2, 57.0 × 57.0 mm2, 99.8 × 99.8 mm2, and 199.6 × 199.6 mm2 fields at center and off‐axis positions were measured using a microDiamond detector and BEAMSCAN® MR water phantom to determine the field penumbra. EBT3 film was exposed to a 190.0 × 220.0 mm2 field composed of two strip segments to assess the tongue‐and‐groove (T&G) effect. Outputs of 100.0 × 100.0 mm2 open and blocked fields at center and off‐axis positions were measured using a PTW TW31021 ion chamber and a film with the full MLC‐blocked field to determine transmission. The minimum gap fields were also exposed on EBT3 film at center and off‐axis positions to assess leakage between leaf tips in the “closed” position. The picket fence test was performed using a megavoltage imager to analyze leaf positional reproducibility. RF shielding was measured via real‐time MR imaging of a homogeneous phantom and quantified using the signal‐to‐noise ratio (SNR).

Results

The leaf widths were 7.00 ± 0.00 and 7.10 ± 0.00 mm for 99.8 × 99.8 and 199.6 × 199.6 mm2 fields, respectively. The leaf side penumbra ranged from 5.11 ± 0.08 to 11.28 ± 0.29 mm and the leaf tips penumbra ranged from 4.47 ± 0.03 to 6.25 ± 0.15 mm for the field size range of 28.4 × 28.4 mm2 to 199.6 × 199.6 mm2. The T&G effect resulted in an underdose of up to 23.41 ± 0.88%. The max leaf transmission was 0.33 ± 0.00% when MLCs were all closed and diaphragms were all opened, and this value was reduced to 0.18 ± 0.00% when the diaphragm blocked the field with a minimum MLC gap. The leaf tip leakage rates were 60.08 ± 0.05% at field center and 2.94 ± 0.00% approximately 100 mm off‐axis. At 6 months, the short‐term leaf position reproducibility was 0.11 mm (2σ), and the long‐term leaf position reproducibility was 0.19 mm (2σ). Leaf motion led to small fluctuations of the SNR of up to 1.64%.

Conclusion

The new MLC system has a comparable T&G effect, low radiation leakage, high positioning reproducibility, and good RF shielding for the Elekta Unity MR‐linac. However, more attention is required for the positional change of the leaf side penumbra.
Deconvolution‐based distortion correction of EPI using analytic single‐voxel point‐spread functions
Authors: Patzig Franz , Mildner Toralf , Schlumm Torsten , Müller Roland , Möller Harald E.
Published: November 2020

Purpose

To develop a postprocessing algorithm that corrects geometric distortions due to spatial variations of the static magnetic field amplitude, B0, and effects from relaxation during signal acquisition in EPI.

Theory and Methods

An analytic, complex point‐spread function is deduced for k‐space trajectories of EPI variants and applied to corresponding acquisitions in a resolution phantom and in human volunteers at 3 T. With the analytic point‐spread function and experimental maps of B0 (and, optionally, the effective transverse relaxation time, ) as input, a point‐spread function matrix operator is devised for distortion correction by a Thikonov‐regularized deconvolution in image space. The point‐spread function operator provides additional information for an appropriate correction of the signal intensity distribution. A previous image combination algorithm for acquisitions with opposite phase blip polarities is adapted to the proposed method to recover destructively interfering signal contributions.

Results

Applications of the proposed deconvolution‐based distortion correction (“DecoDisCo”) algorithm demonstrate excellent distortion corrections and superior performance regarding the recovery of an undistorted intensity distribution in comparison to a multifrequency reconstruction. Examples include full and partial Fourier standard EPI scans as well as double‐shot center‐out trajectories. Compared with other distortion‐correction approaches, DecoDisCo permits additional deblurring to obtain sharper images in cases of significant effects.

Conclusion

Robust distortion corrections in EPI acquisitions are feasible with high quality by regularized deconvolution with an analytic point‐spread function. The general algorithm, which is publicly released on GitHub, can be straightforwardly adapted for specific EPI variants or other acquisition schemes.
Efficient reliability analysis of slopes integrating the random field method and a Gaussian process regression‐based surrogate model
Authors: Zhu Bin , Hiraishi Tetsuya , Pei Huafu , Yang Qing
Published: November 2020

Efficient evaluation of slope stability is a frontier in geo‐disaster prevention fields. While many slope stability evaluation methods, ranging from deterministic to probabilistic, have been proposed, reliability methods are particularly advantageous as they can account for uncertainties during slope stability evaluation. To address the problem of the low efficiency of direct Monte Carlo simulations and overcome the defects of the traditional response surface method, in this work, a novel probabilistic procedure that integrates a Gaussian process regression‐based surrogate model and the random limit equilibrium method for slope stability evaluation while accounting for the spatial variability of soil strength is proposed. The novel Gaussian process regression‐based surrogate model is efficiently used in the Monte Carlo simulation to reduce the number of calls for direct stability analysis of a slope with spatially varied soil strength. To verify the accuracy and efficiency of the proposed procedure, it was applied to three case studies: the first one is a slope in saturated clay under undrained conditions; the second one is a slope for which the friction angle and cohesion values are cross‐correlated; and the third one is a real slope with multiple soil layers. The results obtained from the comparisons with other methods confirmed the precision and feasibility of the proposed procedure.
Recent progress in Bi2WO6‐Based photocatalysts for clean energy and environmental remediation: Competitiveness, challenges, and future perspectives
Authors: Zhu Zheng , Wan Shipeng , Zhao Yunxia , Qin Yong , Ge Xinlei , Zhong Qin , Bu Yunfei
Published: November 2020

The efficient utilization of photocatalytic technology is essential for clean energy and environmental remediation. Bismuth tungstate (Bi2WO6), an appealing Aurivillius phase perovskite, has arisen widespread attention as a visible light responsive photocatalyst applied in environment due to its low cost, nontoxicity, modifiable morphology, and outstanding optical and chemical properties. Nevertheless, the photocatalytic activity of pure Bi2WO6 is unsatisfactory because of its relative small specific surface area, poor quantum yield, and the rapid recombination of photogenerated carriers. Therefore, many strategies, namely, morphological control, dopant or defect introduction, metal deposition, semiconductor combination and surface modification by carbon‐based materials with conjugated π‐structures, have been systematically studied to enhance the photocatalytic performance of Bi2WO6 in the past few years. In order to better explore and study the application of bismuth‐based perovskite oxides in the field of photocatalysis, this review summarizes the recent research progress on Bi2WO6‐based photocatalysts. Moreover, in terms of the improved photocatalytic activity of Bi2WO6‐based photocatalysts, three main applications, including water splitting, pollutants removal, and CO2 reduction, are introduced in detail and critically reviewed. Eventually, the prospects, opportunities, and challenges of Bi2WO6‐based photocatalysts are pointed out. This comprehensive review is expected to put forward valuable suggestions for designing of Bi2WO6‐based photocatalysts applied in clean energy production and environmental remediation on the premise of consolidating the existing theoretical basis of photocatalysis.
Evaluation of interrater reliability of different muscle segmentation techniques in diffusion tensor imaging
Authors: Forsting Johannes , Rehmann Robert , Rohm Marlena , Froeling Martijn , Schlaffke Lara
Published: November 2020

Introduction

Muscle diffusion tensor imaging (mDTI) is a quantitative MRI technique that can provide information about muscular microstructure and integrity. Ultrasound and DTI studies have shown intramuscular differences, and therefore separation of different muscles for analysis is essential. The commonly used methods to assess DTI metrics in muscles are manual segmentation and tract‐based analysis. Recently methods such as volume‐based tractography have been applied to optimize muscle architecture estimation, but can also be used to assess DTI metrics.

Purpose

To evaluate diffusion metrics obtained using three different methods—volume‐based tractography, manual segmentation‐based analysis and tract‐based analysis—with respect to their interrater reliability and their ability to detect intramuscular variance.

Materials and methods

30 volunteers underwent an MRI examination in a 3 T scanner using a 16‐channel Torso XL coil. Diffusion‐weighted images were acquired to obtain DTI metrics. These metrics were evaluated in six thigh muscles using volume‐based tractography, manual segmentation and standard tractography. All three methods were performed by two independent raters to assess interrater reliability by ICC analysis and Bland‐Altman plots. Ability to assess intramuscular variance was compared using an ANOVA with muscle as a between‐subjects factor.

Results

Interrater reliability for all methods was found to be excellent. The highest interrater reliability was found for volume‐based tractography (ICC ≥ 0.967). Significant differences for the factor muscle in all examined diffusion parameters were shown in muscles using all methods (main effect p < 0.001).

Conclusions

Diffusion data can be assessed by volume tractography, standard tractography and manual segmentation with high interrater reliability. Each method produces different results for the investigated DTI parameters. Volume‐based tractography was superior to conventional manual segmentation and tractography regarding interrater reliability and detection of intramuscular variance, while tract‐based analysis showed the lowest coefficients of variation.
Identification of variable stages in murine pancreatic tumors by a multiparametric approach employing hyperpolarized 13C MRSI, 1H diffusivity and 1H T1 MRI
Authors: Martinho Ricardo P. , Bao Qingjia , Markovic Stefan , Preise Dina , Sasson Keren , Agemy Lilach , Scherz Avigdor , Frydman Lucio
Published: November 2020

This study explored the usefulness of multiple quantitative MRI approaches to detect pancreatic ductal adenocarcinomas in two murine models, PAN‐02 and KPC. Methods assayed included 1H T1 and T2 measurements, quantitative diffusivity mapping, magnetization transfer (MT) 1H MRI throughout the abdomen and hyperpolarized 13C spectroscopic imaging. The progress of the disease was followed as a function of its development; studies were also conducted for wildtype control mice and for mice with induced mild acute pancreatitis. Customized methods developed for scanning the motion‐ and artifact‐prone mice abdomens allowed us to obtain quality 1H images for these targeted regions. Contrasts between tumors and surrounding tissues, however, were significantly different. Anatomical images, T2 maps and MT did not yield significant contrast unless tumors were large. By contrast, tumors showed statistically lower diffusivities than their surroundings (≈8.3 ± 0.4 x 10−4 for PAN‐02 and ≈10.2 ± 0.6 x 10−4 for KPC vs 13 ± 1 x 10−3 mm2 s−1 for surroundings), longer T1 relaxation times (≈1.44 ± 0.05 for PAN‐02 and ≈1.45 ± 0.05 for KPC vs 0.95 ± 0.10 seconds for surroundings) and significantly higher lactate/pyruvate ratios by hyperpolarized 13C MR (0.53 ± 0.2 for PAN‐02 and 0.78 ± 0.2 for KPC vs 0.11 ± 0.04 for control and 0.31 ± 0.04 for pancreatitis‐bearing mice). Although the latter could also distinguish early‐stage tumors from healthy animal controls, their response was similar to that in our pancreatitis model. Still, this ambiguity could be lifted using the 1H‐based reporters. If confirmed for other kinds of pancreatic tumors this means that these approaches, combined, can provide a route to an early detection of pancreatic cancer.
Psychometric properties of the Persian version of Instrument of Professional Attitude for Student Nurses (IPASN)
Authors: Eghbali Mohammad , Bandari Razieh , Heravi‐Karimooi Majideh , Ghaesemzadeh Fariba , Montazeri Ali
Published: November 2020

Aim

To evaluate nursing students’ professionalism attitude, it is necessary to use a validated and reliable instrument.

Design

This study aimed to develop the Persian version of the eight‐dimensional professionalism attitude questionnaire for student nurses (Instrument of Professional Attitude for Student Nurses).

Methods

In this cross‐sectional study during March to April 2017, after being translated into Persian and receiving experts’ comments face, content, and construct validity of the questionnaire were sought among nursing students. Internal consistency reliability was examined by estimating the Cronbach's alpha coefficient and stability was estimated by calculating intraclass correlation coefficinet.

Results

A total of 750 students with an average age of 24.15 (SD = 1.32) years participated in the study. Both exploratory and confirmatory factor analyses confirmed the construct of the questionnaire. Cronbach's alpha coefficient for the entire instrument was 0.89 and more than 0.70 for all dimensions.

Also the intraclass correlation coefficient for the questionnaire was found to be 0.92, well above acceptable threshold. The findings approved that the Iranian version of Instrument of Professional Attitude for Student Nurses is a reliable and valid questionnaire. Hence, using this questionnaire to conduct studies is recommended.
Job demands and functional resources moderating assistant and Registered Nurses' intention to leave
Authors: Eriksson Andrea , Jutengren Göran , Dellve Lotta
Published: November 2020

Aims

To investigate how job demands and resources interact with each other to predict intention to leave among assistant nurses and Registered Nurses.

Design

Longitudinal study.

Methods

Questionnaire data were collected yearly during three years (October 2012–December 2014) from Registered Nurses (RN) and assistant nurses (N = 840) employed in Swedish hospitals. Associations and interaction effects of demands and resources were assessed with correlation analyses and regression models.

Results

Job demands predicted assistant nurses' intentions to leave, while resources predicted RNs' intention to leave. For RNs, several resources were functional in moderating the associations between demands and intention to leave: social support, vertical trust, and humanity moderated work pace and workflow moderated emotional demands. For assistant nurses, organizational clarity and interprofessional collaboration moderated emotional demands. None of the resources had a moderating effect on the associations between quantitative demands or illegitimate tasks and intention to leave.
An efficient numerical approach for fractional multidimensional diffusion equations with exponential memory
Authors: Singh Jagdev , Kumar Devendra , Purohit Sunil Dutt , Mishra Aditya Mani , Bohra Mahesh
Published: November 2020

In this article, we suggest a numerical approach based on q‐homotopy analysis Elzaki transform method (q‐HAETM) to solve fractional multidimensional diffusion equations which represents density dynamics in a material undergoing diffusion. We take the noninteger derivative in the Caputo–Fabrizio kind. The proposed method, q‐HAETM is an advanced adaptation in q‐HAM and Elzaki transform method which makes mathematical calculation very effective additionally more accurate. Since, in classical perturbation scheme, the scheme restricted to the small parameter whereas the q‐HAETM is not restricted to the small parameter. By theoretical and numerical evaluation it is observed that q‐HAETM yields an analytical solution in the form of a convergent series. By taking three examples and applying q‐HAETM, the numerical results reveal that the suggested method is straightforward to apply and computationally very effective.
Role of bone marrow biopsy for staging new patients with Ewing sarcoma: A systematic review
Authors: Campbell Kevin M. , Shulman David S. , Grier Holcombe E. , DuBois Steven G.
Published: November 2020

The incidence of bone marrow metastasis (BMM) in newly diagnosed Ewing sarcoma (ES) is variable across studies. An optimal staging strategy for detecting BMM is not defined. While bone marrow (BM) biopsy and/or aspirate (BMBA) have been the gold standard, [F‐18]fluorodeoxyglucose positron emission tomography (FDG‐PET) to detect BMM may decrease reliance on BMBA. We conducted a systematic review to assess incidence of BMM and the role of FDG‐PET. We observed a pooled incidence of BMM by BMBA of 4.8% in all newly diagnosed ES patients and 17.5% among patients with metastatic disease. Only 1.2% of patients had BMM as their sole metastatic site. FDG‐PET detection of BMM compared to BMBA demonstrated pooled 100% sensitivity and 96% specificity, positive predictive value of 75%, and negative predictive value of 100%. In the era of FDG‐PET imaging, omission of BMBA may be considered in patients with otherwise localized disease after initial staging studies.
Design of heat‐triggered shape memory polymers based on ethylene‐acrylic acid copolymer/nitrile‐butadiene rubber thermoplastic vulcanizates
Authors: Sun Yingtao , Hua Jing , Wang Zhaobo
Published: November 2020

Heat‐triggered shape memory polymers (HSMPs) consisting of ethylene‐acrylic acid copolymer (EAA) and nitrile‐butadiene rubber (NBR) were fabricated by peroxide‐induced dynamic vulcanization; meanwhile, in order to realize rapid and reconfigurable shape fixity and shape recovery, a facile and effective strategy was designed. Morphological structure and interface interaction are decisive factors for HSMPs, the FE‐SEM images showed the average diameter of NBR particles in EAA/NBR TPVs was 5 to 8 μm and the strong interface interaction between EAA matrix and NBR particles provided critical assistance in keeping the temporary shape of deformed rubber particles and storing stronger elastic driving force. The shape memory behavior of EAA/NBR TPVs was characterized and the result demonstrated that excellent shape‐fixity (>91%), shape‐recovery (>93%), and fast recovery speed (<30 s) could be obtained at suitable deformation temperature of 95°C. The results of dynamic mechanical analysis and shape memory research showed that the high modulus value supported the improvement of shape‐fixity ratio and the appropriate ratios of EAA/NBR TPVs were the key factors for excellent shape memory performance. The novel HSMPs expected to open up potential applications in the field of sensors and self‐assembling smart devices.