119 research outputs found

    Combined Superbase Ionic Liquid Approach to Separate CO2 from Flue Gas

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    [Image: see text] Superbase ionic liquids (ILs) with a trihexyltetradecylphosphonium cation and a benzimidazolide ([P(66614)][Benzim]) or tetrazolide ([P(66614)][Tetz]) anion were investigated in a dual-IL system allowing the selective capture and separation of CO(2) and SO(2), respectively, under realistic gas concentrations. The results show that [P(66614)][Tetz] is capable of efficiently capturing SO(2) in preference to CO(2) and thus, in a stepwise separation process, protects [P(66614)][Benzim] from the negative effects of the highly acidic contaminant. This results in [P(66614)][Benzim] maintaining >53% of its original CO(2) uptake capacity after 30 absorption/desorption cycles in comparison to the 89% decrease observed after 11 cycles when [P(66614)][Tetz] was not present. Characterization of the ILs post exposure revealed that small amounts of SO(2) were irreversibly absorbed to the [Benzim](−) anion responsible for the decrease in CO(2) capacity. While optimization of this dual-IL system is required, this feasibility study demonstrates that [P(66614)][Tetz] is a suitable sorbent for reversibly capturing SO(2) and significantly extending the lifetime of [P(66614)][Benzim] for CO(2) uptake

    Comparison of Synthetic Computed Tomography Generation Methods, Incorporating Male and Female Anatomical Differences, for Magnetic Resonance Imaging-Only Definitive Pelvic Radiotherapy

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    Purpose: There are several means of synthetic computed tomography (sCT) generation for magnetic resonance imaging (MRI)-only planning; however, much of the research omits large pelvic treatment regions and female anatomical specific methods. This research aimed to apply four of the most popular methods of sCT creation to facilitate MRI-only radiotherapy treatment planning for male and female anorectal and gynecological neoplasms. sCT methods were validated against conventional computed tomography (CT), with regard to Hounsfield unit (HU) estimation and plan dosimetry. Methods and Materials: Paired MRI and CT scans of 40 patients were used for sCT generation and validation. Bulk density assignment, tissue class density assignment, hybrid atlas, and deep learning sCT generation methods were applied to all 40 patients. Dosimetric accuracy was assessed by dose difference at reference point, dose volume histogram (DVH) parameters, and 3D gamma dose comparison. HU estimation was assessed by mean error and mean absolute error in HU value between each sCT and CT. Results: The median percentage dose difference between the CT and sCT was &lt;1.0% for all sCT methods. The deep learning method resulted in the lowest median percentage dose difference to CT at −0.03% (IQR 0.13, −0.31) and bulk density assignment resulted in the greatest difference at −0.73% (IQR −0.10, −1.01). The mean 3D gamma dose agreement at 3%/2 mm among all sCT methods was 99.8%. The highest agreement at 1%/1 mm was 97.3% for the deep learning method and the lowest was 93.6% for the bulk density method. Deep learning and hybrid atlas techniques gave the lowest difference to CT in mean error and mean absolute error in HU estimation. Conclusions: All methods of sCT generation used in this study resulted in similarly high dosimetric agreement for MRI-only planning of male and female cancer pelvic regions. The choice of the sCT generation technique can be guided by department resources available and image guidance considerations, with minimal impact on dosimetric accuracy.</p

    Optimisation and validation of an integrated magnetic resonance imaging-only radiotherapy planning solution

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    Background and purpose: Magnetic resonance imaging (MRI)-only treatment planning is gaining in popularity in radiation oncology, with various methods available to generate a synthetic computed tomography (sCT) for this purpose. The aim of this study was to validate a sCT generation software for MRI-only radiotherapy planning of male and female pelvic cancers. The secondary aim of this study was to improve dose agreement by applying a derived relative electron and mass density (RED) curve to the sCT. Method and materials: Computed tomography (CT) and MRI scans of forty patients with pelvic neoplasms were used in the study. Treatment plans were copied from the CT scan to the sCT scan for dose comparison. Dose difference at reference point, 3D gamma comparison and dose volume histogram analysis was used to validate the dose impact of the sCT. The RED values were optimised to improve dose agreement by using a linear plot. Results: The average percentage dose difference at isocentre was 1.2% and the mean 3D gamma comparison with a criteria of 1%/1 mm was 84.0% ± 9.7%. The results indicate an inherent systematic difference in the dosimetry of the sCT plans, deriving from the tissue densities. With the adapted REDmod table, the average percentage dose difference was reduced to −0.1% and the mean 3D gamma analysis improved to 92.9% ± 5.7% at 1%/1 mm. Conclusions: CT generation software is a viable solution for MRI-only radiotherapy planning. The option makes it relatively easy for departments to implement a MRI-only planning workflow for cancers of male and female pelvic anatomy.</p

    A robust Pax7EGFP mouse that enables the visualization of dynamic behaviors of muscle stem cells.

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    BACKGROUND: Pax7 is a transcription factor involved in the specification and maintenance of muscle stem cells (MuSCs). Upon injury, MuSCs leave their quiescent state, downregulate Pax7 and differentiate, contributing to skeletal muscle regeneration. In the majority of regeneration studies, MuSCs are isolated by fluorescence-activated sorting (FACS), based on cell surface markers. It is known that MuSCs are a heterogeneous population and only a small percentage of isolated cells are true stem cells that are able to self-renew. A strong Pax7 reporter line would be valuable to study the in vivo behavior of Pax7-expressing stem cells. METHODS: We generated and characterized the muscle properties of a new transgenic Pax7EGFP mouse. Utilizing traditional immunofluorescence assays, we analyzed whole embryos and muscle sections by fluorescence microscopy, in addition to whole skeletal muscles by 2-photon microscopy, to detect the specificity of EGFP expression. Skeletal muscles from Pax7EGFP mice were also evaluated in steady state and under injury conditions. Finally, MuSCs-derived from Pax7EGFP and control mice were sorted and analyzed by FACS and their myogenic activity was comparatively examined. RESULTS: Our studies provide a new Pax7 reporter line with robust EGFP expression, detectable by both flow cytometry and fluorescence microscopy. Pax7EGFP-derived MuSCs have identical properties to that of wild-type MuSCs, both in vitro and in vivo, excluding any positional effect due to the transgene insertion. Furthermore, we demonstrated high specificity of EGFP to label MuSCs in a temporal manner that recapitulates the reported Pax7 expression pattern. Interestingly, immunofluorescence analysis showed that the robust expression of EGFP marks cells in the satellite cell position of adult muscles in fixed and live tissues. CONCLUSIONS: This mouse could be an invaluable tool for the study of a variety of questions related to MuSC biology, including but not limited to population heterogeneity, polarity, aging, regeneration, and motility, either by itself or in combination with mice harboring additional genetic alterations

    A new negative control gene for amino acid biosynthesis in Saccharomyces cerevisiae

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    Enzyme levels in multiple amino acid biosynthetic pathways in yeast are coregulated. This control is effected largely at the transcriptional level by a number. of regulatory genes. We report the isolation and characterization of a new negative regulatory gene, GCD4 , for this general control system. GCD4 mutations are recessive and define a single Mendelian gene on chromosome 111. A gcd4 mutation results in resistance to different amino acid analogs and elevated, but fully inducible, mRNA levels of genes under general control. Epistasis analysis indicates that GCD4 acts more directly than the positive regulators GCN1, GCN2, GCN3 and GCN5 , but less directly than GCN4 , on the transcription of the amino acid biosynthetic genes. These data imply that GCD4 is a negative regulator of the positive effector, GCN4 . Although GCD4 occupies the same position relative to the GCN genes as other GCD genes, it produces a unique phenotype. These results illustrate the diversity of function of negative regulators in general control.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46958/1/294_2004_Article_BF00447382.pd

    Genitourinary quality-of-life comparison between urethral sparing prostate stereotactic body radiation therapy monotherapy and virtual high-dose-rate brachytherapy boost

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    Purpose: Although radiation dose escalation improves prostate cancer disease control, it can cause increased toxicity. Genitourinary (GU) symptoms after prostate radiation therapy affect patient health-related quality of life (QoL). We compared patient-reported GU QoL outcomes following 2 alternative urethral sparing stereotactic body radiation therapy regimens. Methods and Materials: Expanded Prostate Cancer Index Composite (EPIC)–26 GU scores were compared between 2 urethral sparing stereotactic body radiation therapy trials. The SPARK trial prescribed a “Monotherapy” dose of 36.25 Gy in 5 fractions to the prostate. The PROMETHEUS trial prescribed 2 phases: a 19- to 21-Gy in 2 fractions “Boost” to the prostate, followed by 46 Gy in 23 fractions or 36 Gy in 12 fractions. The biological effective dose (BED) for urethral toxicity was 123.9 Gy for Monotherapy and 155.8 to 171.2 Gy for Boost. Mixed effects logistic regression models were utilized to estimate the difference in the odds of a minimal clinically important change from baseline EPIC-26 GU score between regimens at each follow-up. Results: 46 Monotherapy and 149 Boost patients completed baseline EPIC-26 scoring. Mean EPIC-26 GU scores revealed statistically superior urinary incontinence outcomes for Monotherapy at 12 months (mean difference, 6.9; 95% confidence interval [CI], 1.6-12.1; P = .01) and 36 months (mean difference, 9.6; 95% CI, 4.1-15.1; P < .01). Monotherapy also revealed superior mean urinary irritative/obstructive outcomes at 12 months (mean difference, 6.9; 95% CI, 2.0-12.9; P < .01) and 36 months (mean difference, 6.3; 95% CI, 1.9-10.8; P < .01). For both domains and at all time points, the absolute differences were <10%. There were no significant differences in the odds of reporting a minimal clinically important change between regimens at any time point. Conclusions: Even in the presence of urethral sparing, the higher BED delivered in the Boost schedule may have a small adverse effect on GU QoL compared with Monotherapy. However, this did not translate to statistically significant differences in minimal clinically important changes. Whether the higher BED of the boost arm offers an efficacy advantage is being investigated in the Trans Tasman Radiation Oncology Group 18.01 NINJA randomized trial

    Validation of an MRI-only planning workflow for definitive pelvic radiotherapy

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    Purpose: Previous work on Magnetic Resonance Imaging (MRI) only planning has been applied to limited treatment regions with a focus on male anatomy. This research aimed to validate the use of a hybrid multi-atlas synthetic computed tomography (sCT) generation technique from a MRI, using a female and male atlas, for MRI only radiation therapy treatment planning of rectum, anal canal, cervix and endometrial malignancies. Patients and methods: Forty patients receiving radiation treatment for a range of pelvic malignancies, were separated into male (n = 20) and female (n = 20) cohorts for the creation of gender specific atlases. A multi-atlas local weighted voting method was used to generate a sCT from a T1-weighted VIBE DIXON MRI sequence. The original treatment plans were copied from the CT scan to the corresponding sCT for dosimetric validation. Results: The median percentage dose difference between the treatment plan on the CT and sCT at the ICRU reference point for the male cohort was − 0.4% (IQR of 0 to − 0.6), and − 0.3% (IQR of 0 to − 0.6) for the female cohort. The mean gamma agreement for both cohorts was &gt; 99% for criteria of 3%/2 mm and 2%/2 mm. With dose criteria of 1%/1 mm, the pass rate was higher for the male cohort at 96.3% than the female cohort at 93.4%. MRI to sCT anatomical agreement for bone and body delineated contours was assessed, with a resulting Dice score of 0.91 ± 0.2 (mean ± 1 SD) and 0.97 ± 0.0 for the male cohort respectively; and 0.96 ± 0.0 and 0.98 ± 0.0 for the female cohort respectively. The mean absolute error in Hounsfield units (HUs) within the entire body for the male and female cohorts was 59.1 HU ± 7.2 HU and 53.3 HU ± 8.9 HU respectively. Conclusions: A multi-atlas based method for sCT generation can be applied to a standard T1-weighted MRI sequence for male and female pelvic patients. The implications of this study support MRI only planning being applied more broadly for both male and female pelvic sites. Trial registration This trial was registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) (www.anzctr.org.au) on 04/10/2017. Trial identifier ACTRN12617001406392.</p

    The purple line as a measure of labour progress: a longitudinal study

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    Background: Vaginal examination (VE) and assessment of the cervix is currently considered to be the gold standard for assessment of labour progress. It is however inherently imprecise with studies indicating an overall accuracy for determining the diameter of the cervix at between 48-56%. Furthermore, VEs can be unpleasant, intrusive and embarrassing for women, and are associated with the risk of introducing infection. In light of increasing concern world wide about the use of routine interventions in labour it may be time to consider alternative, less intrusive means of assessing progress in labour. The presence of a purple line during labour, seen to rise from the anal margin and extend between the buttocks as labour progresses has been reported. The study described in this paper aimed to assess in what percentage of women in labour a purple line was present, clear and measurable and to determine if any relationship existed between the length of the purple line and cervical dilatation and/or station of the fetal head. Methods: This longitudinal study observed 144 women either in spontaneous labour (n=112) or for induction of labour (n=32) from admission through to final VE. Women were examined in the lateral position and midwives recorded the presence or absence of the line throughout labour immediately before each VE. Where present, the length of the line was measured using a disposable tape measure. Within subjects correlation, chi-squared test for independence, and independent samples t-test were used to analyse the data. Results: The purple line was seen at some point in labour for 109 women (76%). There was a medium positive correlation between length of the purple line and cervical dilatation (r=+0.36, n=66, P=0.0001) and station of the fetal head (r=+0.42, n=56, P&lt;0.0001). Conclusions: The purple line does exist and there is a medium positive correlation between its length and both cervical dilatation and station of the fetal head. Where the line is present, it may provide a useful guide for clinicians of labour progress along side other measures. Further research is required to assess whether measurement of the line is acceptable to women in labour and also clinicians

    Protocol for Northern Ireland Caries Prevention in Practice Trial (NIC-PIP) trial: a randomised controlled trial to measure the effects and costs of a dental caries prevention regime for young children attending primary care dental services

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    <p>Abstract</p> <p>Background</p> <p>Dental caries is a persistent public health problem with little change in the prevalence in young children over the last 20 years. Once a child contracts the disease it has a significant impact on their quality of life. There is good evidence from Cochrane reviews including trials that fluoride varnish and regular use of fluoride toothpaste can prevent caries.</p> <p>The Northern Ireland Caries Prevention in Practice Trial (NIC-PIP) trial will compare the costs and effects of a caries preventive package (fluoride varnish, toothpaste, toothbrush and standardised dental health education) with dental health education alone in young children.</p> <p>Methods/Design</p> <p>A randomised controlled trial on children initially aged 2 and 3 years old who are regular attenders at the primary dental care services in Northern Ireland. Children will be recruited and randomised in dental practices. Children will be randomised to the prevention package of both fluoride varnish (twice per year for three years), fluoride toothpaste (1,450 ppm F) (supplied twice per year), a toothbrush (supplied twice a year) or not; both test and control groups receive standardised dental health education delivered by the dentist twice per year. Randomisation will be conducted by the Belfast Trust Clinical Research Support Centre ([CRSC] a Clinical Trials Unit).</p> <p>1200 participants will be recruited from approximately 40 dental practices. Children will be examined for caries by independent dental examiners at baseline and will be excluded if they have caries. The independent dental examiners will examine the children again at 3 years blinded to study group.</p> <p>The primary end-point is whether the child develops caries (cavitation into dentine) or not over the three years. One secondary outcome is the number of carious surfaces in the primary dentition in children who experience caries. Other secondary outcomes are episodes of pain, extraction of primary teeth, other adverse events and costs which will be obtained from parental questionnaires.</p> <p>Discussion</p> <p>This is a pragmatic trial conducted in general dental practice. It tests a composite caries prevention intervention, which represents an evidence based approach advocated by current guidance from the English Department of Health which is feasible to deliver to all low risk (caries free) children in general dental practice. The trial will provide valuable information to policy makers and clinicians on the costs and effects of caries prevention delivered to young children in general dental practice.</p> <p>Trial registration</p> <p>EudraCT No: 2009 - 010725 - 39</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN36180119">ISRCTN36180119</a></p> <p>Ethics Reference No: 09/H1008/93:</p
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