228 research outputs found
Specialist versus primary care prostate cancer follow-up:A process evaluation of a randomized controlled trial
Background: A randomized controlled trial (RCT) is currently comparing the effectiveness of specialist- versus primary care-based prostate cancer follow-up. This process evaluation assesses the reach and identified constructs for the implementation of primary care-based follow-up. Methods: A mixed-methods approach is used to assess the reach and the implementation through the Consolidated Framework for Implementation Research. We use quantitative data to evaluate the reach of the RCT and qualitative data (interviews) to indicate the perspectives of patients (n = 15), general practitioners (GPs) (n = 10), and specialists (n = 8). Thematic analysis is used to analyze the interview transcripts. Results: In total, we reached 402 (67%) patients from 12 hospitals and randomized them to specialist- (n = 201) or to primary care-based (n = 201) follow-up. From the interviews, we identify several advantages of primary care- versus specialist-based follow-up: it is closer to home, more accessible, and the relationship is more personal. Nevertheless, participants also identified challenges: guidelines should be implemented, communication and collaboration between primary and secondary care should be improved, quality indicators should be collected, and GPs should be compensated. Conclusion: Within an RCT context, 402 (67%) patients and their GPs were willing to receive/provide primary care-based follow-up. If the RCT shows that primary care is equally as effective as specialist-based follow-up, the challenges identified in this study need to be addressed to enable a smooth transition of prostate cancer follow-up to primary care. Netherlands Trial Registry, Trial NL7068 (NTR7266)
Longitudinal correlations between intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) MRI during radiotherapy in prostate cancer patients
Purpose: Intravoxel incoherent motion (IVIM) is a promising technique that can acquire perfusion information without the use of contrast agent, contrary to the more established dynamic contrast-enhanced (DCE) technique. This is of interest for treatment response monitoring, where patients can be imaged on each treatment fraction. In this study, longitudinal correlations between IVIM- and DCE parameters were assessed in prostate cancer patients receiving radiation treatment.Materials and Methods: 20 prostate cancer patients were treated on a 1.5 T MR-linac with 20 x 3 or 3.1 Gy. Weekly IVIM and DCE scans were acquired. Tumors, the peripheral zone (PZ), and the transition zone (TZ) were delineated on a T2-weighted scan acquired on the first fraction. IVIM and DCE scans were registered to this scan and the delineations were propagated. Median values from these delineations were used for further analysis. The IVIM parameters D, f, D* and the product fD* were calculated. The Tofts model was used to calculate the DCE parameters Ktrans, kep and ve. Pearson correlations were calculated for the IVIM and DCE parameters on values from the first fraction for each region of interest (ROI). For longitudinal analysis, the repeated measures correlation coefficient was used to determine correlations between IVIM and DCE parameters in each ROI.Results: When averaging over patients, an increase during treatment in all IVIM and DCE parameters was observed in all ROIs, except for D in the PZ and TZ. No significant Pearson correlations were found between any pair of IVIM and DCE parameters measured on the first fraction. Significant but low longitudinal correlations were found for some combinations of IVIM and DCE parameters in the PZ and TZ, while no significant longitudinal correlations were found in the tumor. Notably in the TZ, for both f and fD*, significant longitudinal correlations with all DCE parameters were found.Conclusions: The increase in IVIM- and DCE parameters when averaging over patients indicates a measurable response to radiation treatment with both techniques. Although low, significant longitudinal correlations were found which suggests that IVIM could potentially be used as an alternative to DCE for treatment response monitoring.</p
Peptide exchange on MHC-I by TAPBPR is driven by a negative allostery release cycle.
Chaperones TAPBPR and tapasin associate with class I major histocompatibility complexes (MHC-I) to promote optimization (editing) of peptide cargo. Here, we use solution NMR to investigate the mechanism of peptide exchange. We identify TAPBPR-induced conformational changes on conserved MHC-I molecular surfaces, consistent with our independently determined X-ray structure of the complex. Dynamics present in the empty MHC-I are stabilized by TAPBPR and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized according to the global stability of the final pMHC-I product and anneal in a native-like conformation to be edited by TAPBPR. Our results demonstrate an inverse relationship between MHC-I peptide occupancy and TAPBPR binding affinity, wherein the lifetime and structural features of transiently bound peptides control the regulation of a conformational switch located near the TAPBPR binding site, which triggers TAPBPR release. These results suggest a similar mechanism for the function of tapasin in the peptide-loading complex
No weighting for healthy sustainable local planning: Evaluation of a participatory appraisal tool for rationality and inclusivity
This paper is concerned with the contribution that project, plan and policy appraisal can make to effective decision making when shaping a built environment that needs to respond to the demands of local voices and also concerns for global sustainability and for population well-being. It argues that effectiveness depends on appraisal processes being rational, based on sound science, and also inclusive, involving stakeholders and implementers. A particular problem in all respects is the widespread reliance of decision makers on methods that use weighting. Although these give the appearance of validity, authority and objectivity, the paper argues that such methods are not compatible with the key tenets of appraisal and decision making that can address the challenges of localism, sustainability, health and inclusion. The paper advocates and evaluates a new technique, SPECTRUM, trialled in practice, which has been developed to meet these challenges. Specific attention is paid to its role in the development of the award winning ICON housing scheme in the Houndwood development at Street in Somerset, England. © 2013 Copyright Taylor and Francis Group, LLC
The Amazon Epiphyte Network: A First Glimpse Into Continental-Scale Patterns of Amazonian Vascular Epiphyte Assemblages
Epiphytes are still an understudied plant group in Amazonia. The aim of this study was to identify distributional patterns and conservation priorities for vascular epiphyte assemblages (VEA) across Amazonia. We compiled the largest Amazonian epiphyte plot database to date, through a multinational collaborative effort of 22 researchers and 32 field sites located across four Amazonian countries – the Amazonian Epiphyte Network (AEN). We addressed the following continental-scale questions by utilizing the AEN database comprising 96,448 epiphyte individuals, belonging to 518 vascular taxa, and growing on 10,907 tree individuals (phorophytes). Our objectives here are, first, to present a qualitative evaluation of the geographic distribution of the study sites and highlight regional lacunae as priorities for future quantitative inventories. Second, to present the floristic patterns for Amazonia-wide VEA and third, to combine multivariate analyses and rank abundance curves, controlled by major Amazonian habitat types, to determine how VEA vary geographically and ecologically based on major Amazonian habitat types. Three of the most striking patterns found are that: (1) VEA are spatially structured as floristic similarity decays with geographic distance; (2) a core group of 22 oligarchic taxa account for more than a half of all individuals; and (3) extensive floristic sampling gaps still exist, mainly across the highly threatened southern Amazonian deforestation belt. This work represents a first step toward unveiling distributional pattern of Amazonian VEA, which is important to guide future questions on ecology and species distribution ranges of VEA once the collaborative database grows allowing a clearer view of patterns
Sentinel node procedure to select clinically localized prostate cancer patients with occult nodal metastases for whole pelvis radiotherapy
Background: Accurate identification of men who harbor nodal metastases is neces-sary to select patients who most likely benefit from whole pelvis radiotherapy (WPRT). Limited sensitivity of diagnostic imaging approaches for the detection of nodal micrometastases has led to the exploration of the sentinel lymph node biopsy (SLNB). Objective: To evaluate whether SLNB can be used as a tool to select pathologically node-positive patients who likely benefit from WPRT. Design, setting, and participants: We included 528 clinically node-negative primary prostate cancer (PCa) patients with an estimated nodal risk of >5% treated between 2007 and 2018. Intervention: A total of 267 patients were directly treated with prostate-only radio-therapy (PORT; non-SLNB group), while 261 patients underwent SLNB to remove lymph nodes directly draining from the primary tumor prior to radiotherapy (SLNB group); pN0 patients were treated with PORT, while pN1 patients were offered WPRT. Outcome measurements and statistical analysis: Biochemical recurrence-free survival (BCRFS) and radiological recurrence-free survival (RRFS) were compared using propensity score weighted (PSW) Cox proportional hazard models. Results and limitations: The median follow-up was 71 mo. Occult nodal metastases were found in 97 (37%) SLNB patients (median metastasis size: 2 mm). Adjusted 7-yr BCRFS rates were 81% (95% confidence interval [CI] 77-86%) in the SLNB group and 49% (95% CI 43-56%) in the non-SLNB group. The corresponding adjusted 7-yr RRFS rates were 83% (95% CI 78-87%) and 52% (95% CI 46-59%), respectively. In the PSW multivariable Cox regression analysis, SLNB was associated with improved BCRFS (hazard ratio [HR] 0.38, 95% CI 0.25-0.59, p < 0.001) and RRFS (HR 0.44, 95% CI 0.28-0.69, p < 0.001). Limitations include the bias inherent to the study's Conclusions: SLNB-based selection of pN1 PCa patients for WPRT was associated efit from the addition of pelvis radiotherapy. This strategy results in a longer dura (c) 2023 The Author(s). Published by Elsevier B.V. on behalf of European Association of Urology. This is an open access article under the CC BY license (http://creativecommons.Radiolog
Drug export and allosteric coupling in a multidrug transporter revealed by molecular simulations
Multidrug resistance is a serious problem in current chemotherapy. The efflux system largely responsible for resistance in Escherichia coli contains the drug transporter, AcrB. The structures of AcrB were solved in 2002 as the symmetric homo-trimer, and then in 2006 as the asymmetric homo-trimer. The latter suggested a functionally rotating mechanism. Here, by molecular simulations of the AcrB porter domain, we uncovered allosteric coupling and the drug export mechanism in the AcrB trimer. Allosteric coupling stabilized the asymmetric structure with one drug molecule bound, which validated the modelling. Drug dissociation caused a conformational change and stabilized the symmetric structure, providing a unified view of the structures reported in 2002 and 2006. A dynamic study suggested that, among the three potential driving processes, only protonation of the drug-bound protomer can drive the functional rotation and simultaneously export the drug
Permissivity of the NCI-60 cancer cell lines to oncolytic Vaccinia Virus GLV-1h68
<p>Abstract</p> <p>Background</p> <p>Oncolytic viral therapy represents an alternative therapeutic strategy for the treatment of cancer. We previously described GLV-1h68, a modified Vaccinia Virus with exclusive tropism for tumor cells, and we observed a cell line-specific relationship between the ability of GLV-1h68 to replicate in vitro and its ability to colonize and eliminate tumor in vivo.</p> <p>Methods</p> <p>In the current study we surveyed the in vitro permissivity to GLV-1h68 replication of the NCI-60 panel of cell lines. Selected cell lines were also tested for permissivity to another Vaccinia Virus and a vesicular stomatitis virus (VSV) strain. In order to identify correlates of permissity to viral infection, we measured transcriptional profiles of the cell lines prior infection.</p> <p>Results</p> <p>We observed highly heterogeneous permissivity to VACV infection amongst the cell lines. The heterogeneity of permissivity was independent of tissue with the exception of B cell derivation. Cell lines were also tested for permissivity to another Vaccinia Virus and a vesicular stomatitis virus (VSV) strain and a significant correlation was found suggesting a common permissive phenotype. While no clear transcriptional pattern could be identified as predictor of permissivity to infection, some associations were observed suggesting multifactorial basis permissivity to viral infection.</p> <p>Conclusions</p> <p>Our findings have implications for the design of oncolytic therapies for cancer and offer insights into the nature of permissivity of tumor cells to viral infection.</p
Single blind randomized Phase III trial to investigate the benefit of a focal lesion ablative microboost in prostate cancer (FLAME-trial): study protocol for a randomized controlled trial
Background: The treatment results of external beam radiotherapy for intermediate and high risk prostate cancer patients are insufficient with five-year biochemical relapse rates of approximately 35%. Several randomized trials have shown that dose escalation to the entire prostate improves biochemical disease free survival. However, further dose escalation to the whole gland is limited due to an unacceptable high risk of acute and late toxicity. Moreover, local recurrences often originate at the location of the macroscopic tumor, so boosting the radiation dose at the macroscopic tumor within the prostate might increase local control. A reduction of distant metastases and improved survival can be expected by reducing local failure. The aim of this study is to investigate the benefit of an ablative microboost to the macroscopic tumor within the prostate in patients treated with external beam radiotherapy for prostate cancer.Methods/Design: The FLAME-trial (Focal Lesion Ablative Microboost in prostatE cancer) is a single blind randomized controlled phase III trial. We aim to include 566 patients (283 per treatment arm) with intermediate or high risk adenocarcinoma of the prostate who are scheduled for external beam radiotherapy using fiducial markers for position verification. With this number of patients, the expected increase in five-year freedom from biochemical failure rate of 10% can be detected with a power of 80%. Patients allocated to the standard arm receive a dose of 77 Gy in 35 fractions to the entire prostate and patients in the experimental arm receive 77 Gy to the entire prostate and an additional integrated microboost to the macroscopic tumor of 95 Gy in 35 fractions. The secondary outcome measures include treatment-related toxicity, quality of life and disease-specific survival. Furthermore, by localizing the recurrent tumors within the prostate during follow-up and correlating this with the delivered dose, we can obtain accurate dose-effect information for both the macroscopic tumor and subclinical disease in prostate cancer. The rationale, study design and the first 50 patients included are described.Biological, physical and clinical aspects of cancer treatment with ionising radiatio
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