Assessment of Peripheral Airway Function following Chronic Allergen Challenge in a Sheep Model of Asthma

BACKGROUND: There is increasing evidence that the small airways contribute significantly to the pathophysiology of asthma. However, due to the difficulty in accessing distal lung regions in clinical settings, functional changes in the peripheral airways are often overlooked in studies of asthmatic patients. The aim of the current study was to characterize progressive changes in small airway function in sheep repeatedly challenged with house dust mite (HDM) allergen. METHODOLOGY/PRINCIPAL FINDINGS: Four spatially separate lung segments were utilized for HDM challenges. The right apical, right medial, right caudal and left caudal lung segments received 0, 8, 16 and 24 weekly challenges with HDM respectively. A wedged-bronchoscope technique was used to assess changes in peripheral resistance (R(p)) at rest, and in response to specific and non-specific stimuli throughout the trial. Allergen induced inflammatory cell infiltration into bronchoalveolar lavage and increases in R(p) in response to HDM and methacholine were localized to treated lung segments, with no changes observed in adjacent lung segments. The acute response to HDM was variable between sheep, and was significantly correlated to airway responsiveness to methacholine (r(s) = 0.095, P<0.01). There was no correlation between resting R(p) and the number of weeks of HDM exposure. Nor was there a correlation between the magnitude of early-phase airway response and the number of HDM-challenges. CONCLUSIONS: Our findings indicate that airway responses to allergic and non-allergic stimuli are localized to specific treated areas of the lung. Furthermore, while there was a decline in peripheral airway function with HDM exposure, this decrease was not correlated with the length of allergen challenge

Immune response to allergens in sheep sensitized to house dust mite

<p>Abstract</p> <p>Background</p> <p>House dust mite (HDM) allergens are a major cause of allergic asthma. Most studies using animal models of allergic asthma have used rodents sensitized with the 'un-natural' allergen ovalbumin. It has only recently been recognized that the use of animal models based on HDM provide a more relevant insight into the allergen-induced mechanisms that underpin human allergic disease. We have previously described a sheep model of human allergic asthma that uses <it>Dermatophagoides pteronyssinus </it>HDM. The present study extends our understanding of the immune effects of HDM and the allergens Der p 1 and Der p 2 in the sheep model of asthma.</p> <p>Methods</p> <p>Peripheral blood sera from non-sensitized (control) sheep and sheep sensitized to HDM was collected to determine immunoglobulin (Ig) reactivities to HDM, Der p 1 and Der p 2 by ELISA. Bronchoalveolar lavage (BAL) fluid collected following allergen challenge was also assessed for the presence of HDM-specific antibodies. To examine the cellular immune response to HDM allergens, T cell proliferation and cutaneous responses were assessed in sensitized and control sheep.</p> <p>Results</p> <p>Strong HDM- and Der p 1-specific IgE, IgG₁, IgG₂and IgA serum responses were observed in sensitized sheep, while detectable levels of HDM-specific IgG₁and IgA were seen in BAL fluid of allergen-challenged lungs. In contrast, minimal antibody reactivity was observed to Der p 2. Marked T cell proliferation and late phase cutaneous responses, accompanied by the recruitment of eosinophils, indicates the induction of a cellular and delayed-type hypersensitivity (DTH) type II response by HDM and Der p 1 allergen, but not Der p 2.</p> <p>Conclusion</p> <p>This work characterizes the humoral and cellular immune effects of HDM extract and its major constituent allergens in sheep sensitized to HDM. The effects of allergen in HDM-sensitized sheep were detectable both locally and systemically, and probably mediated via enzymatic and immune actions of the major HDM allergen Der p 1. This study extends our understanding of the actions of this important allergen relevant to human allergic asthma and its effects in sheep experimentally sensitized to HDM allergens.</p

Most patients reported positively or neutrally of having served as controls in the trials within cohorts design

Objectives: To evaluate patients’ experience of having served as controls without a notification at the time of randomization in the context of the trial within cohorts (TwiCs) design. Methods: Patients were asked for their opinion on having served as controls in TwiCs, before and after having been provided the trial results. Patients had provided broad consent to randomization at cohort entry and had served as controls in one of two TwiCs (an exercise program after breast cancer treatment or radiotherapy dose-escalation for rectal cancer). Results: Two to 6 years after cohort entry, 15% (n = 16) of all patients remembered having provided broad consent to randomization. Before disclosure of trial results, 47% (n = 52) of patients thought positively, 45% (n = 50) neutrally, and 2% (n = 2) negatively of having served as controls in one of the two trials. Seventeen percent (n = 18) of patients were positive, 65% (n = 71) neutral, and 11% (n = 12) negative about not having been notified when serving as controls. The survey results were comparable after disclosure of trial results. Conclusions: These results support the use of the TwiCs design with the staged-informed consent procedure. Keeping patients engaged and aware of the consents provided might further improve patients’ experience of serving as controls in TwiCs

Oncology patients were found to understand and accept the Trials within Cohorts design

Background and Objective: The Trials within Cohorts design aims to reduce recruitment difficulties and disappointment bias in pragmatic trials. On cohort enrollment, broad informed consent for randomization is asked, after which cohort participants can be randomized to interventions or serve as controls without further notification. We evaluated patients' recollection, understanding, and acceptance of broad consent in a clinical oncology setting. Methods: We surveyed 610 patients with cancer participating in ongoing TwiCs; 482 patients (79%) responded, of which 312 patients shortly after cohort enrollment, 108 patients after randomization to an intervention (12-18 months after cohort enrollment), and a random sample of 62 cohort participants who had not been selected for interventions (1-6 months after cohort enrollment). Results: Shortly after providing cohort consent, 76% of patients (238/312) adequately remembered whether they had given broad consent for randomization. Of patients randomly offered interventions, 76% (82/108) remembered giving broad consent for randomization; 41% (44/108) understood they were randomly selected, 44% (48/108) were not interested in selection procedures, and 10% (11/108) did not understand selection was random. Among patients not selected for interventions, 42% (26/62) understood selection was random; 89% felt neutral regarding the scenario of "not being selected for an intervention while your data were being used in comparison with patients receiving interventions,"10% felt reassured (6/62) and 2% scared/insecure (2/62). Conclusion: Patients adequately remember giving broad consent for randomization shortly after cohort enrollment and after being offered an intervention, but recollection is lower in those never selected for interventions. Patients are acceptant of serving as control without further notifications. (c) 2020 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Accumulated bladder wall dose is correlated with patient-reported acute urinary toxicity in prostate cancer patients treated with stereotactic, daily adaptive MR-guided radiotherapy

Background and purpose: Magnetic resonance (MR)-guided linear accelerators (MR-Linac) enable accurate estimation of delivered doses through dose accumulation using daily MR images and treatment plans. We aimed to assess the association between the accumulated bladder (wall) dose and patient-reported acute urinary toxicity in prostate cancer (PCa) patients treated with stereotactic body radiation therapy (SBRT). Materials and methods: One-hundred-and-thirty PCa patients treated on a 1.5 T MR-Linac were included. Patients filled out International Prostate Symptom Scores (IPSS) questionnaires at baseline, 1 month, and 3 months post-treatment. Deformable image registration-based dose accumulation was performed to reconstruct the delivered dose. Dose parameters for both bladder and bladder wall were correlated with a clinically relevant increase in IPSS (≥ 10 points) and/or start of alpha-blockers within 3 months using logistic regression. Results: Thirty-nine patients (30%) experienced a clinically relevant IPSS increase and/or started with alpha-blockers. Bladder D5cm3, V10–35Gy (in %), and Dmean and Bladder wall V10–35Gy (cm3 and %) and Dmean were correlated with the outcome (odds ratios 1.04–1.33, p-values 0.001–0.044). Corrected for baseline characteristics, bladder V10–35Gy (in %) and Dmean and bladder wall V10–35Gy (cm3 and %) and Dmean were still correlated with the outcome (odds ratios 1.04–1.30, p-values 0.001–0.028). Bladder wall parameters generally showed larger AUC values. Conclusion: This is the first study to assess the correlation between accumulated bladder wall dose and patient-reported urinary toxicity in PCa patients treated with MR-guided SBRT. The dose to the bladder wall is a promising parameter for prediction of patient-reported urinary toxicity and therefore warrants prospective validation and consideration in treatment planning

Clinical utility of convolutional neural networks for treatment planning in radiotherapy for spinal metastases

Background and purpose: Spine delineation is essential for high quality radiotherapy treatment planning of spinal metastases. However, manual delineation is time-consuming and prone to interobserver variability. Automatic spine delineation, especially using deep learning, has shown promising results in healthy subjects. We aimed to evaluate the clinical utility of deep learning-based vertebral body delineations for radiotherapy planning purposes. Materials and methods: A multi-scale convolutional neural network (CNN) was used for automatic segmentation and labeling. Two approaches were tested: the combined approach using one CNN for both segmentation and labeling, and the sequential approach using separate CNN's for these tasks. Training and internal validation data included 580 vertebrae, external validation data included 202 vertebrae. For quantitative assessment, Dice similarity coefficient (DSC) and Hausdorff distance (HD) were used. Axial slices from external images were presented to radiation oncologists for subjective evaluation. Results: Both approaches performed comparably during the internal validation (DSC: 96.7%, HD: 3.6 mm), but the sequential approach proved more robust during the external validation (DSC: 94.5% vs 94.4%, p < 0.001, HD: 4.5 vs 7.1 mm, p < 0.001). Subsequently, subjective evaluation of this sequential approach showed that experienced radiation oncologists could distinguish automatic from human-made contours in 63% of cases. They rated automatic contours clinically acceptable in 77% of cases, compared to 88% of human-made contours. Conclusion: We present a feasible approach for automatic vertebral body delineation using two variants of a multi-scale CNN. This approach generates high quality automatic delineations, which can save time in a clinical radiotherapy workflow

Remineralization of lytic spinal metastases after radiotherapy

BACKGROUND CONTEXT: Palliative radiotherapy (RT) can lead to remineralization of osteolytic lesions thereby potentially restoring some of the weight-bearing capacity and preventing vertebral collapse. It is not clear, however, under which circumstances remineralization of osteolytic lesions occurs. PURPOSE: The aim of this study was to investigate the change in bone mineral density in spinal metastases after RT compared to a reference region, and find associated factors. STUDY DESIGN: Retrospective analysis within prospective observational cohort OUTCOME MEASURES: change in bone mineral density measured in Hounsfield Units (HU). PATIENT SAMPLE: patients treated with RT for (painful) bone metastases. METHODS: Patients with spinal metastases were included if computed tomography scans both pre- and post-RT were available. Bone density was measured in HU. A region of interest (ROI) was drawn manually in the metastatic lesion. As a reference, a measurement of bone density in adjacent, unaffected, and non-irradiated vertebrae was used. Factors tested for association were origin of the primary tumor, RT dose and fractionation scheme, and concomitant use of bisphosphonates. RESULTS: A total of 31 patients with 49 spinal metastases, originating from various primary tumors, were included. The median age on baseline was 58 years (IQR: 53–63) and median time between baseline and follow-up scan was 8.2 months (IQR: 3.0–18.4). Difference in HU in the lesion before and after treatment was 146.9 HU (95% CI 68.4–225.4; p<.01). Difference in HU in the reference vertebra between baseline and first follow-up was 19.1 HU (95% CI -47.9 to 86.0; p=.58). Difference between reference vertebrae and metastatic lesions on baseline was -194.1 HU (95% CI -276.2 to -112.0; p<.01). After RT, this difference was reduced to -50.3 HU (95% CI -199.6 to 99.0; p=.52). Patients using bisphosphonates showed a greater increase in HU, 194.1 HU versus 60.6 HU, p=.01. CONCLUSIONS: Palliative radiation of osteolytic lytic spinal metastases is positively associated with an increased bone mineral density at follow-up. The use of bisphosphonates was linked to an increased bone mineral density when used during or after RT

Stereotactic Radiotherapy Followed by Surgical Stabilization Within 24 h for Unstable Spinal Metastases; A Stage I/IIa Study According to the IDEAL Framework

Background: Routine treatment for unstable spinal metastases consists of surgical stabilization followed by external beam radiotherapy (EBRT) or stereotactic body radiotherapy (SBRT) after a minimum of 1–2 weeks to allow for initial wound healing. Although routine treatment, there are several downsides. First, radiotherapy induced pain relief is delayed by the time interval required for wound healing. Second, EBRT often requires multiple hospital visits and only 60% of the patients experience pain relief. Third, spinal implants cause imaging artifacts hindering SBRT treatment planning and delivery. Reversing the order of surgery and radiotherapy, with dose sparing of the surgical area by SBRT, could overcome these disadvantages and by eliminating the interval between the two treatments, recovery, and palliation may occur earlier.Design: The safety of SBRT followed by surgical stabilization within 24 h for the treatment of unstable spinal metastases was investigated. Safety was evaluated using the Common-Toxicity-Criteria-Adverse-Events-4.0, with the occurrence of wound complications within 90-days being the primary concern.Results: Between June-2015 and January-2017, 13 patients underwent SBRT followed by surgical stabilization for unstable spinal metastases. The median time between SBRT and surgery was 17-h (IQR 5–19). None of the patients experienced wound complications. Improvements in pain and quality of life were observed over time for all patients.Conclusion: SBRT followed by surgical stabilization within 24 h for the treatment of unstable spinal metastases is safe. Palliation may be experienced earlier and with both treatments being performed in one hospital admission the treatment burden decreases