Corrigendum: Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies

[This corrects the article DOI: 10.3389/fimmu.2023.1230049.].

Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies

Iatrogenic vascular air embolism is a relatively infrequent event but is associated with significant morbidity and mortality. These emboli can arise in many clinical settings such as neurosurgery, cardiac surgery, and liver transplantation, but more recently, endoscopy, hemodialysis, thoracentesis, tissue biopsy, angiography, and central and peripheral venous access and removal have overtaken surgery and trauma as significant causes of vascular air embolism. The true incidence may be greater since many of these air emboli are asymptomatic and frequently go undiagnosed or unreported. Due to the rarity of vascular air embolism and because of the many manifestations, diagnoses can be difficult and require immediate therapeutic intervention. An iatrogenic air embolism can result in both venous and arterial emboli whose anatomic locations dictate the clinical course. Most clinically significant iatrogenic air emboli are caused by arterial obstruction of small vessels because the pulmonary gas exchange filters the more frequent, smaller volume bubbles that gain access to the venous circulation. However, there is a subset of patients with venous air emboli caused by larger volumes of air who present with more protean manifestations. There have been significant gains in the understanding of the interactions of fluid dynamics, hemostasis, and inflammation caused by air emboli due to in vitro and in vivo studies on flow dynamics of bubbles in small vessels. Intensive research regarding the thromboinflammatory changes at the level of the endothelium has been described recently. The obstruction of vessels by air emboli causes immediate pathoanatomic and immunologic and thromboinflammatory responses at the level of the endothelium. In this review, we describe those immunologic and thromboinflammatory responses at the level of the endothelium as well as evaluate traditional and novel forms of therapy for this rare and often unrecognized clinical condition.

Resonant Acoustic Rheometry to Measure Coagulation Kinetics in Hemophilia A and Healthy Plasma: A Novel Viscoelastic Method

Compared with conventional coagulation tests and factor-specific assays, viscoelastic hemostatic assays (VHAs) can provide a more thorough evaluation of clot formation and lysis but have several limitations including clot deformation. In this proof-of-concept study, we test a noncontact technique, termed resonant acoustic rheometry (RAR), for measuring the kinetics of human plasma coagulation. Specifically, RAR utilizes a dual-mode ultrasound technique to induce and detect surface oscillation of blood samples without direct physical contact and measures the resonant frequency of the surface oscillation over time, which is reflective of the viscoelasticity of the sample. Analysis of RAR results of normal plasma allowed defining a set of parameters for quantifying coagulation. RAR detected a flat-line tracing of resonant frequency in hemophilia A plasma that was corrected with the addition of tissue factor. Our RAR results captured the kinetics of plasma coagulation and the newly defined RAR parameters correlated with increasing tissue factor concentration in both healthy and hemophilia A plasma. These findings demonstrate the feasibility of RAR as a novel approach for VHA, providing the foundation for future studies to compare RAR parameters to conventional coagulation tests, factor-specific assays, and VHA parameters.

COVID-associated non-vasculitic thrombotic retiform purpura of the face and extremities: A case report

SARS-CoV-2 infection can manifest many rashes. However, thrombotic retiform purpura rarely occurs during COVID-19 illness. Aggressive anti-COVID-19 therapy with a high-dose steroid regimen led to rapid recovery. This immunothrombotic phenomenon likely represents a poor type 1 interferon response and complement activation on the endothelial surface in response to acute infection.

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either-or Proposition

There has been a significant interest in the last decade in the use of viscoelastic tests (VETs) to determine the hemostatic competence of bleeding patients. Previously, common coagulation tests (CCTs) such as the prothrombin time (PT) and partial thromboplastin time (PTT) were used to assist in the guidance of blood component and hemostatic adjunctive therapy for these patients. However, the experience of decades of VET use in liver failure with transplantation, cardiac surgery, and trauma has now spread to obstetrical hemorrhage and congenital and acquired coagulopathies. Since CCTs measure only 5 to 10% of the lifespan of a clot, these assays have been found to be of limited use for acute surgical and medical conditions, whereby rapid results are required. However, there are medical indications for the PT/PTT that cannot be supplanted by VETs. Therefore, the choice of whether to use a CCT or a VET to guide blood component therapy or hemostatic adjunctive therapy may often require consideration of both methodologies. In this review, we provide examples of the relative indications for CCTs and VETs in monitoring hemostatic competence of bleeding patients.

Use of a Mylar filter to eliminate vacuum ultraviolet pulse pileup in low-energy x-ray measurements

We describe a method to reduce vacuum ultraviolet (VUV) pulse pileup (PPU) in x-ray pulse-height Silicon Drift Detector (SDD) signals. An Amptek FAST SDD, with C1 (Si₃N₄) window, measures bremsstrahlung emitted from PFRC-2 plasma to extract the electron temperature (T_e) and density (n_e). The C1 window has low transmissivity for photons with energy below 200 eV though will transmit some VUV and soft x-ray photons, which PFRC-2 plasmas abundantly emit. Multi-VUV-photon PPU contaminates the interpretation of x rays with energy > 100 eV, particularly in a low-energy exponential tail. The predicted low transmissivity of ∼1 μm thick Mylar [polyethylene terephthalate (PET)] to photons of energy <100 eV led to the selection of Mylar as the candidate filter to reduce VUV PPU. Experiments were conducted on an x-ray tube with a graphite target and on a quasi-Maxwellian tenuous plasma (n_e ∼ 10⁹ cm^-3) with effective temperatures reaching 1500 eV. A Mylar filter thickness of 850 nm is consistent with the results. The Mylar-filter-equipped SDD was then used on the PFRC-2 plasma, showing a substantial reduction in the low-energy x-ray signal, supporting our hypothesis of the importance of VUV PPU. We describe the modeling and experiments performed to characterize the effect of the Mylar filter on SDD measurements.

An update on oral cavity cancer: epidemiological trends, prevention strategies and novel approaches in diagnosis and prognosis

In the UK, the incidence of oral cavity cancer continues to rise, with an increase of around 60% over the past 10 years. Many patients still present with advanced disease, often resulting in locoregional recurrence and poor outcomes, which has not changed significantly for over four decades. Changes in aetiology may also be emerging, given the decline of smoking in developed countries. Therefore, new methods to better target prevention, improve screening and detect recurrence are needed. High-throughput 'omics' technologies appear promising for future individual-level diagnosis and prognosis. However, given this is a relatively rare cancer with significant intra-tumour heterogeneity and variation in patient response, reliable biomarkers have been difficult to elucidate. From a public health perspective, implementing these novel technologies into current services would require substantial practical, financial and ethical considerations. This may be difficult to justify and implement at present, therefore focus remains on early detection using new patient-led follow-up strategies. This paper reviews the latest evidence on epidemiological trends in oral cavity cancer to help identify at risk groups, population-based approaches for prevention, in addition to potential cutting-edge approaches in the diagnosis and prognosis of this disease.

Suboptimal sleep and incident cardiovascular disease among African Americans in the Jackson Heart Study (JHS)

BACKGROUND

Suboptimal sleep, including insufficient/long sleep duration and poor sleep quality, is a risk factor for cardiovascular disease (CVD) common but there is little information among African Americans, a group with a disproportionate CVD burden. The current study examined the association between suboptimal sleep and incident CVD among African Americans.

METHODS

This study included 4,522 African Americans without CVD at baseline (2000-2004) of the Jackson Heart Study (JHS). Self-reported sleep duration was defined as very short (<6 h/night), short (6 h/night), recommended (7-8 h/night), and long (≥9 h/night). Participants' self-reported sleep quality was defined as "high" and "low" quality. Suboptimal sleep was defined by low quality sleep and/or insufficient/long sleep duration. Incident CVD was a composite of incident coronary heart disease and stroke. Associations between suboptimal sleep and incident CVD were examined using Cox proportional hazards models over 15 follow-up years with adjustment for predictors of CVD risk and obstructive sleep apnea.

RESULTS

Sample mean age was 54 years (SD = 13), 64% female and 66% reported suboptimal sleep. Suboptimal sleep was not associated with incident CVD after covariate adjustment [HR(95% CI) = 1.18(0.97-1.46)]. Long [HR(95%CI) = 1.32(1.02-1.70)] and very short [HR(95% CI) = 1.56(1.06-2.30)] sleep duration were associated with incident CVD relative to recommended sleep duration. Low quality sleep was not associated with incident CVD (p = 0.413).

CONCLUSIONS

Long and very short self-reported sleep duration but not self-reported sleep quality were associated with increased hazard of incident CVD.

Autosegmentation of the rectum on megavoltage image guidance scans

Autosegmentation of image guidance (IG) scans is crucial for streamlining and optimising delivered dose calculation in radiotherapy. By accounting for interfraction motion, daily delivered dose can be accumulated and incorporated into automated systems for adaptive radiotherapy. Autosegmentation of IG scans is challenging due to poorer image quality than typical planning kilovoltage computed tomography (kVCT) systems, and the resulting reduction of soft tissue contrast in regions such as the pelvis makes organ boundaries less distinguishable. Current autosegmentation solutions generally involve propagation of planning contours to the IG scan by deformable image registration (DIR). Here, we present a novel approach for primary autosegmentation of the rectum on megavoltage IG scans acquired during prostate radiotherapy, based on the Chan-Vese algorithm. Pre-processing steps such as Hounsfield unit/intensity scaling, identifying search regions, dealing with air, and handling the prostate, are detailed. Post-processing features include identification of implausible contours (nominally those affected by muscle or air), 3D self-checking, smoothing, and interpolation. In cases where the algorithm struggles, the best estimate on a given slice may revert to the propagated kVCT rectal contour. Algorithm parameters were optimised systematically for a training cohort of 26 scans, and tested on a validation cohort of 30 scans, from 10 patients. Manual intervention was not required. Comparing Chan-Vese autocontours with contours manually segmented by an experienced clinical oncologist achieved a mean Dice Similarity Coefficient of 0.78 (SE < 0.011). This was comparable with DIR methods for kVCT and CBCT published in the literature. The autosegmentation system was developed within the VoxTox Research Programme for accumulation of delivered dose to the rectum in prostate radiotherapy, but may have applicability to further anatomical sites and imaging modalities.

A method for acquiring random range uncertainty probability distributions in proton therapy

In treatment planning we depend upon accurate knowledge of geometric and range uncertainties. If the uncertainty model is inaccurate then the plan will produce under-dosing of the target and/or overdosing of OAR. We aim to provide a method for which centre and site-specific population range uncertainty due to inter-fraction motion can be quantified to improve the uncertainty model in proton treatment planning. Daily volumetric MVCT data from previously treated radiotherapy patients has been used to investigate inter-fraction changes to water equivalent path-length (WEPL). Daily image-guidance scans were carried out for each patient and corrected for changes in CTV position (using rigid transformations). An effective depth algorithm was used to determine residual range changes, after corrections had been applied, throughout the treatment by comparing WEPL within the CTV at each fraction for several beam angles. As a proof of principle this method was used to quantify uncertainties for inter-fraction range changes for a sample of head and neck patients of [Formula: see text] mm, [Formula: see text] mm and overall [Formula: see text] mm. For prostate [Formula: see text] mm, [Formula: see text] mm and overall [Formula: see text] mm. The choice of beam angle for head and neck did not affect the inter-fraction range error significantly; however this was not the same for prostate. Greater range changes were seen using a lateral beam compared to an anterior beam for prostate due to relative motion of the prostate and femoral heads. A method has been developed to quantify population range changes due to inter-fraction motion that can be adapted for the clinic. The results of this work highlight the importance of robust planning and analysis in proton therapy. Such information could be used in robust optimisation algorithms or treatment plan robustness analysis. Such knowledge will aid in establishing beam start conditions at planning and for establishing adaptive planning protocols.

Automatic contour propagation using deformable image registration to determine delivered dose to spinal cord in head-and-neck cancer radiotherapy

To determine delivered dose to the spinal cord, a technique has been developed to propagate manual contours from kilovoltage computed-tomography (kVCT) scans for treatment planning to megavoltage computed-tomography (MVCT) guidance scans. The technique uses the Elastix software to perform intensity-based deformable image registration of each kVCT scan to the associated MVCT scans. The registration transform is then applied to contours of the spinal cord drawn manually on the kVCT scan, to obtain contour positions on the MVCT scans. Different registration strategies have been investigated, with performance evaluated by comparing the resulting auto-contours with manual contours, drawn by oncologists. The comparison metrics include the conformity index (CI), and the distance between centres (DBC). With optimised registration, auto-contours generally agree well with manual contours. Considering all 30 MVCT scans for each of three patients, the median CI is \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$0.759 \pm 0.003$ \end{document}0.759±0.003, and the median DBC is (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$0.87 \pm 0.01$ \end{document}0.87±0.01) mm. An intra-observer comparison for the same scans gives a median CI of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$0.820 \pm 0.002$ \end{document}0.820±0.002 and a DBC of (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$0.64 \pm 0.01$ \end{document}0.64±0.01) mm. Good levels of conformity are also obtained when auto-contours are compared with manual contours from one observer for a single MVCT scan for each of 30 patients, and when they are compared with manual contours from six observers for two MVCT scans for each of three patients. Using the auto-contours to estimate organ position at treatment time, a preliminary study of 33 patients who underwent radiotherapy for head-and-neck cancers indicates good agreement between planned and delivered dose to the spinal cord.

Randomised clinical trial: addition of alginate-antacid (Gaviscon Double Action) to proton pump inhibitor therapy in patients with breakthrough symptoms

BACKGROUND

Symptomatic breakthrough in proton pump inhibitor (PPI)-treated gastro-oesophageal reflux disease (GERD) patients is a common problem with a range of underlying causes. The nonsystemic, raft-forming action of alginates may help resolve symptoms.

AIM

To assess alginate-antacid (Gaviscon Double Action, RB, Slough, UK) as add-on therapy to once-daily PPI for suppression of breakthrough reflux symptoms.

METHODS

In two randomised, double-blind studies (exploratory, n=52; confirmatory, n=262), patients taking standard-dose PPI who had breakthrough symptoms, assessed by Heartburn Reflux Dyspepsia Questionnaire (HRDQ), were randomised to add-on Gaviscon or placebo (20 mL after meals and bedtime). The exploratory study endpoint was change in HRDQ score during treatment vs run-in. The confirmatory study endpoint was "response" defined as ≥3 days reduction in the number of "bad" days (HRDQ [heartburn/regurgitation] >0.70) during treatment vs run-in.

RESULTS

In the exploratory study, significantly greater reductions in HRDQ scores (heartburn/regurgitation) were observed in the Gaviscon vs placebo (least squares mean difference [95% CI] -2.10 [-3.71 to -0.48]; P=.012). Post hoc "responder" analysis of the exploratory study also revealed significantly more Gaviscon patients (75%) achieved ≥3 days reduction in "bad" days vs placebo patients (36%), P=.005. In the confirmatory study, symptomatic improvement was observed with add-on Gaviscon (51%) but there was no significant difference in response vs placebo (48%) (OR (95% CI) 1.15 (0.69-1.91), P=.5939).

CONCLUSIONS

Adding Gaviscon to PPI reduced breakthrough GERD symptoms but a nearly equal response was observed for placebo. Response to intervention may vary according to whether symptoms are functional in origin.

Delivered dose can be a better predictor of rectal toxicity than planned dose in prostate radiotherapy

Background and purpose

For the first time, delivered dose to the rectum has been calculated and accumulated throughout the course of prostate radiotherapy using megavoltage computed tomography (MVCT) image guidance scans. Dosimetric parameters were linked with toxicity to test the hypothesis that delivered dose is a stronger predictor of toxicity than planned dose.

Material and methods

Dose–surface maps (DSMs) of the rectal wall were automatically generated from daily MVCT scans for 109 patients within the VoxTox research programme. Accumulated-DSMs, representing total delivered dose, and planned-DSMs, from planning CT data, were parametrised using Equivalent Uniform Dose (EUD) and ‘DSM dose-width’, the lateral dimension of an ellipse fitted to a discrete isodose cluster. Associations with 6 toxicity endpoints were assessed using receiver operator characteristic curve analysis.

Results

For rectal bleeding, the area under the curve (AUC) was greater for accumulated dose than planned dose for DSM dose-widths up to 70 Gy. Accumulated 65 Gy DSM dose-width produced the strongest spatial correlation (AUC 0.664), while accumulated EUD generated the largest AUC overall (0.682). For proctitis, accumulated EUD was the only reportable predictor (AUC 0.673). Accumulated EUD was systematically lower than planned EUD.

Conclusions

Dosimetric parameters extracted from accumulated DSMs have demonstrated stronger correlations with rectal bleeding and proctitis, than planned DSMs.

Nonsurgical treatment and early return to activity leads to improved Achilles tendon fatigue mechanics and functional outcomes during early healing in an animal model

Achilles tendon ruptures are common and devastating injuries; however, an optimized treatment and rehabilitation protocol has yet to be defined. Therefore, the objective of this study was to investigate the effects of surgical repair and return to activity on joint function and Achilles tendon properties after 3 weeks of healing. Sprague-Dawley rats (N = 100) received unilateral blunt transection of their Achilles tendon. Animals were then randomized into repaired or non-repaired treatments, and further randomized into groups that returned to activity after 1 week (RTA1) or after 3 weeks (RTA3) of limb casting in plantarflexion. Limb function, passive joint mechanics, and tendon properties (mechanical, organizational using high frequency ultrasound, histological, and compositional) were evaluated. Results showed that both treatment and return to activity collectively affected limb function, passive joint mechanics, and tendon properties. Functionally, RTA1 animals had increased dorsiflexion ROM and weight bearing of the injured limb compared to RTA3 animals 3-weeks post-injury. Such functional improvements in RTA1 tendons were evidenced in their mechanical fatigue properties and increased cross sectional area compared to RTA3 tendons. When RTA1 was coupled with nonsurgical treatment, superior fatigue properties were achieved compared to repaired tendons. No differences in cell shape, cellularity, GAG, collagen type I, or TGF-β staining were identified between groups, but collagen type III was elevated in RTA3 repaired tendons. The larger tissue area and increased fatigue resistance created in RTA1 tendons may prove critical for optimized outcomes in early Achilles tendon healing following complete rupture. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2172-2180, 2016.

The effect of deprivation on the incidence of mandibular fractures in a British city

AIM

To examine the relationship between social and material deprivation and mandibular fractures.

METHOD

Three hundred and forty three consecutive patients who underwent mandibular fracture fixation were selected for the study. After exclusions, 290 were divided into age groups and ranked according to their Index of Multiple Deprivation (IMD) score. Rankings were determined using postcodes, and divided into quintiles for statistical analysis.

RESULTS

Ages ranged from 7 to 82 with 146 (50%) patients aged between 20 and 29. Males accounted for 85% of cases. The most common site of fracture was the angle (n = 195) and assault was shown to be the most common mechanism of injury (63.3%). A strong relationship was demonstrated between fractures of the mandible and worsening deprivation, with the most striking relationship seen with fractures sustained as a consequence of assault. Females were less likely than males to sustain a fracture of the mandible as a consequence of assault; however, when assault was the mechanism of injury they were also likely to be from a deprived background.

CONCLUSION

This study has demonstrated that a strong relationship exists between deprivation and the incidence of mandibular fractures in our catchment area. Fractures that resulted from interpersonal violence were shown to have a particularly strong correlation with deprivation.

Randomized clinical trial of postoperative chewing gum versus standard care after colorectal resection

Background

Chewing gum may stimulate gastrointestinal motility, with beneficial effects on postoperative ileus suggested in small studies. The primary aim of this trial was to determine whether chewing gum reduces length of hospital stay (LOS) after colorectal resection. Secondary aims included examining bowel habit symptoms, complications and healthcare costs.

Methods

This clinical trial allocated patients randomly to standard postoperative care with or without chewing gum (sugar‐free gum for at least 10 min, four times per day on days 1–5) in five UK hospitals. The primary outcome was LOS. Cox regression was used to calculate hazard ratios for LOS.

Results

Data from 402 of 412 patients, of whom 199 (49·5 per cent) were allocated to chewing gum, were available for analysis. Some 40 per cent of patients in both groups had laparoscopic surgery, and all study sites used enhanced recovery programmes. Median (i.q.r.) LOS was 7 (5–11) days in both groups (P = 0·962); the hazard ratio for use of gum was 0·94 (95 per cent c.i. 0·77 to 1·15; P = 0·557). Participants allocated to gum had worse quality of life, measured using the EuroQoL 5D‐3L, than controls at 6 and 12 weeks after operation (but not on day 4). They also had more complications graded III or above according to the Dindo–Demartines–Clavien classification (16 versus 6 in the group that received standard care) and deaths (11 versus 0), but none was classed as related to gum. No other differences were observed.

Conclusion

Chewing gum did not alter the return of bowel function or LOS after colorectal resection. Registration number: ISRCTN55784442 (http://www.controlled-trials.com).

No advantage observed

Interaction of a dengue virus NS1-derived peptide with the inhibitory receptor KIR3DL1 on natural killer cells

Killer immunoglobulin-like receptors (KIRs) interact with human leucocyte antigen (HLA) class I ligands and play a key role in the regulation and activation of NK cells. The functional importance of KIR-HLA interactions has been demonstrated for a number of chronic viral infections, but to date only a few studies have been performed in the context of acute self-limited viral infections. During our investigation of CD8(+) T cell responses to a conserved HLA-B57-restricted epitope derived from dengue virus (DENV) non-structural protein-1 (NS1), we observed substantial binding of the tetrameric complex to non-T/non-B lymphocytes in peripheral blood mononuclear cells (PBMC) from a long-standing clinical cohort in Thailand. We confirmed binding of the NS1 tetramer to CD56(dim) NK cells, which are known to express KIRs. Using depletion studies and KIR-transfected cell lines, we demonstrated further that the NS1 tetramer bound the inhibitory receptor KIR3DL1. Phenotypical analysis of PBMC from HLA-B57(+) subjects with acute DENV infection revealed marked activation of NS1 tetramer-binding natural killer (NK) cells around the time of defervescence in subjects with severe dengue disease. Collectively, our findings indicate that subsets of NK cells are activated relatively late in the course of acute DENV illness and reveal a possible role for specific KIR-HLA interactions in the modulation of disease outcomes.

Exploiting biological and physical determinants of radiotherapy toxicity to individualize treatment

The recent advances in radiation delivery can improve tumour control probability (TCP) and reduce treatment-related toxicity. The use of intensity-modulated radiotherapy (IMRT) in particular can reduce normal tissue toxicity, an objective in its own right, and can allow safe dose escalation in selected cases. Ideally, IMRT should be combined with image guidance to verify the position of the target, since patients, target and organs at risk can move day to day. Daily image guidance scans can be used to identify the position of normal tissue structures and potentially to compute the daily delivered dose. Fundamentally, it is still the tolerance of the normal tissues that limits radiotherapy (RT) dose and therefore tumour control. However, the dose-response relationships for both tumour and normal tissues are relatively steep, meaning that small dose differences can translate into clinically relevant improvements. Differences exist between individuals in the severity of toxicity experienced for a given dose of RT. Some of this difference may be the result of differences between the planned dose and the accumulated dose (DA). However, some may be owing to intrinsic differences in radiosensitivity of the normal tissues between individuals. This field has been developing rapidly, with the demonstration of definite associations between genetic polymorphisms and variation in toxicity recently described. It might be possible to identify more resistant patients who would be suitable for dose escalation, as well as more sensitive patients for whom toxicity could be reduced or avoided. Daily differences in delivered dose have been investigated within the VoxTox research programme, using the rectum as an example organ at risk. In patients with prostate cancer receiving curative RT, considerable daily variation in rectal position and dose can be demonstrated, although the median position matches the planning scan well. Overall, in 10 patients, the mean difference between planned and accumulated rectal equivalent uniform doses was -2.7 Gy (5%), and a dose reduction was seen in 7 of the 10 cases. If dose escalation was performed to take rectal dose back to the planned level, this should increase the mean TCP (as biochemical progression-free survival) by 5%. Combining radiogenomics with individual estimates of DA might identify almost half of patients undergoing radical RT who might benefit from either dose escalation, suggesting improved tumour cure or reduced toxicity or both.

Defining robustness protocols: a method to include and evaluate robustness in clinical plans

We aim to define a site-specific robustness protocol to be used during the clinical plan evaluation process. Plan robustness of 16 skull base IMPT plans to systematic range and random set-up errors have been retrospectively and systematically analysed. This was determined by calculating the error-bar dose distribution (ebDD) for all the plans and by defining some metrics used to define protocols aiding the plan assessment. Additionally, an example of how to clinically use the defined robustness database is given whereby a plan with sub-optimal brainstem robustness was identified. The advantage of using different beam arrangements to improve the plan robustness was analysed. Using the ebDD it was found range errors had a smaller effect on dose distribution than the corresponding set-up error in a single fraction, and that organs at risk were most robust to the range errors, whereas the target was more robust to set-up errors. A database was created to aid planners in terms of plan robustness aims in these volumes. This resulted in the definition of site-specific robustness protocols. The use of robustness constraints allowed for the identification of a specific patient that may have benefited from a treatment of greater individuality. A new beam arrangement showed to be preferential when balancing conformality and robustness for this case. The ebDD and error-bar volume histogram proved effective in analysing plan robustness. The process of retrospective analysis could be used to establish site-specific robustness planning protocols in proton therapy. These protocols allow the planner to determine plans that, although delivering a dosimetrically adequate dose distribution, have resulted in sub-optimal robustness to these uncertainties. For these cases the use of different beam start conditions may improve the plan robustness to set-up and range uncertainties.

Evaluating competing and emerging technologies for stereotactic body radiotherapy and other advanced radiotherapy techniques

Stereotactic body radiotherapy (SBRT) refers to the precise irradiation of an image-defined extracranial lesion, using a high total radiation dose delivered in a small number of fractions. A significant proportion of SBRT treatment has been successfully delivered using conventional gantry-based linear accelerators with appropriate image guidance and motion management techniques, although a number of specialist systems are also available. Evaluating the competing SBRT technologies is difficult due to frequent refinements to all major platforms. Comparison of geometric accuracy or treatment planning performance can be hard to interpret and may not provide much useful information. Nevertheless, a general specification overview can provide information that may help radiotherapy providers decide on an appropriate system for their centre. A number of UK randomised controlled trials (RCTs) have shown that better radiotherapy techniques yield better results. RCTs should play an important part in the future evaluation of SBRT, especially where there is a smaller volume of existing data, and where outcomes from conventional radiotherapy are very good. RCT comparison of SBRT with surgery is more difficult due to the radically different treatment arms, although successful recruitment can be possible if the lessons from previous failed trials are learned. The evaluation of new technology poses a number of challenges to the conventional RCT methodology, and there may be situations where it is genuinely not possible, with careful observational studies or decision modelling being more appropriate. Further development in trial design may have an important role in providing clinical evidence in a more timely manner.

Geant4 simulation of the Elekta XVI kV CBCT unit for accurate description of potential late toxicity effects of image-guided radiotherapy

This paper describes the modelisation of the Elekta XVI Cone Beam Computed Tomography (CBCT) machine components with Geant4 and its validation against calibration data taken for two commonly used machine setups. Preliminary dose maps of simulated CBCTs coming from this modelisation work are presented. This study is the first step of a research project, GHOST, aiming to improve the understanding of late toxicity risk in external beam radiotherapy patients by simulating dose depositions integrated from different sources (imaging, treatment beam) over the entire treatment plan. The second cancer risk will then be derived from different models relating irradiation dose and second cancer risk.

Prophylactic radiotherapy against heterotopic ossification following internal fixation of acetabular fractures: a comparative estimate of risk

OBJECTIVE

Radiotherapy (RT) is effective in preventing heterotopic ossification (HO) around acetabular fractures requiring surgical reconstruction. We audited outcomes and estimated risks from RT prophylaxis, and alternatives of indometacin or no prophylaxis.

METHODS

34 patients underwent reconstruction of acetabular fractures through a posterior approach, followed by a 8-Gy single fraction. The mean age was 44 years. The mean time from surgery to RT was 1.1 days. The major RT risk is radiation-induced fatal cancer. The International Commission on Radiological Protection (ICRP) method was used to estimate risk, and compared with a method (Trott and Kemprad) specifically for estimating RT risk for benign disease. These were compared with risks associated with indometacin and no prophylaxis.

RESULTS

28 patients (82%) developed no HO; 6 developed Brooker Class I; and none developed Class II-IV HO. The ICRP method suggests a risk of fatal cancer in the range of 1 in 1000 to 1 in 10,000; the Trott and Kemprad method suggests 1 in 3000. For younger patients, this may rise to 1 in 2000; and for elderly patients, it may fall to 1 in 6000. The risk of death from gastric bleeding or perforation from indometacin is 1 in 180 to 1 in 900 in older patients. Without prophylaxis risk of death from reoperation to remove HO is 1 in 4000 to 1 in 30,000.

CONCLUSION

These results are encouraging, consistent with much larger series and endorse our multidisciplinary management. Risk estimates can be used in discussion with patients.

ADVANCES IN KNOWLEDGE

The risk from RT prophylaxis is small, it is safer than indometacin and substantially overlaps with the range for no prophylaxis.

Evaluation of dengue virus strains for human challenge studies

Discordance between the measured levels of dengue virus neutralizing antibody and clinical outcomes in the first-ever efficacy study of a dengue tetravalent vaccine (Lancet, Nov 2012) suggests a need to re-evaluate the process of pre-screening dengue vaccine candidates to better predict clinical benefit prior to large-scale vaccine trials. In the absence of a reliable animal model and established correlates of protection for dengue, a human dengue virus challenge model may provide an approach to down-select vaccine candidates based on their ability to reduce risk of illness following dengue virus challenge. We report here the challenge of flavivirus-naïve adults with cell culture-passaged dengue viruses (DENV) in a controlled setting that resulted in uncomplicated dengue fever (DF). This sets the stage for proof-of-concept efficacy studies that allow the evaluation of dengue vaccine candidates in healthy adult volunteers using qualified DENV challenge strains well before they reach field efficacy trials involving children. Fifteen flavivirus-naïve adult volunteers received 1 of 7 DENV challenge strains (n=12) or placebo (n=3). Of the twelve volunteers who received challenge strains, five (two DENV-1 45AZ5 and three DENV-3 CH53489 cl24/28 recipients) developed DF, prospectively defined as ≥2 typical symptoms, ≥48h of sustained fever (>100.4°F) and concurrent viremia. Based on our study and historical data, we conclude that the DENV-1 and DENV-3 strains can be advanced as human challenge strains. Both of the DENV-2 strains and one DENV-4 strain failed to meet the protocol case definition of DF. The other two DENV-4 strains require additional testing as the illness approximated but did not satisfy the case definition of DF. Three volunteers exhibited effusions (1 pleural/ascites, 2 pericardial) and 1 volunteer exhibited features of dengue (rash, lymphadenopathy, neutropenia and thrombocytopenia), though in the absence of fever and symptoms. The occurrence of effusions in milder DENV infections counters the long-held belief that plasma leakage syndromes are restricted to dengue hemorrhagic fever/dengue shock syndromes (DHF/DSS). Hence, the human dengue challenge model may be useful not only for predicting the efficacy of vaccine and therapeutic candidates in small adult cohorts, but also for contributing to our further understanding of the mechanisms behind protection and virulence.

The efficacy and safety of a pharmacologic protocol for maintaining coronary artery bypass patients at a higher mean arterial pressure during cardiopulmonary bypass. 1998

A recent randomized trial of higher versus lower mean arterial pressure (MAP) during cardiopulmonary bypass (CPB) showed that higher MAP on CPB was associated with a lower incidence of overall cardiac and neurologic morbidity and mortality in coronary artery bypass graft surgery (CABG) patients. Cardiopulmonary bypass MAP was controlled pharmacologically while CPB flow was held constant for any given period. The objective of the present study was to assess the efficacy and safety of this pharmacologic protocol. Two hundred forty-eight patients participated in the study; the mean age was 65.8 ± 9.4 years, 20% were women, and the mean preoperative ejection fraction was 48%. The low-flow corrected CPB MAP attained for the low and high MAP groups was 56.7 ± 5.0 mmHg and 77.7 ± 7.1 mmHg, respectively (p = 0.0001). Major cardiac and neurologic outcomes, postoperative blood loss, renal dysfunction, intensive care unit (ICU) stay, and duration of intubation were not found to be significantly associated with any drug in the pharmacologic protocol. These findings support that the pharmacologic protocol used to maintain CABG patients at higher MAP on CPB is both efficacious and safe.

Consideration of the likely benefit from implementation of prostate image-guided radiotherapy using current margin sizes: a radiobiological analysis

OBJECTIVE

To estimate the benefit of introduction of image-guided radiotherapy (IGRT) to prostate radiotherapy practice with current clinical target volume-planning target volume (PTV) margins of 5-10 mm.

METHODS

Systematic error data collected from 50 patients were used together with a random error of σ=3.0 mm to model non-IGRT treatment. IGRT was modelled with residual errors of Σ=σ=1.5 mm. Population tumour control probability (TCP(pop)) was calculated for two three-dimensional conformal radiotherapy techniques: two-phase and concomitant boost. Treatment volumes and dose prescriptions were ostensibly the same. The relative field sizes of the treatment techniques, distribution of systematic errors and correlations between movement axes were examined.

RESULTS

The differences in TCP(pop) between the IGRT and non-IGRT regimes were 0.3% for the two-phase and 1.5% for the concomitant boost techniques. A 2-phase plan, in each phase of which the 95% isodose conformed to its respective PTV, required fields that were 3.5 mm larger than those required for the concomitant boost plan. Despite the larger field sizes, the TCP (without IGRT) in the two-phase plan was only 1.7% higher than the TCP in the concomitant boost plan. The deviation of craniocaudal systematic errors (p=0.02) from a normal distribution, and the correlation of translations in the craniocaudal and anteroposterior directions (p<0.0001) were statistically significant.

CONCLUSIONS

The expected population benefit of IGRT for the modelled situation was too small to be detected by a clinical trial of reasonable size, although there was a significant benefit to individual patients. For IGRT to have an observable population benefit, the trial would need to use smaller margins than those used in this study. Concomitant treatment techniques permit smaller fields and tighter conformality than two phases planned separately.

Clinical medical sciences for undergraduate dental students in the United Kingdom and Ireland - a curriculum

The technical aspects of dentistry need to be practised with insight into the spectrum of human diseases and illnesses and how these impact upon individuals and society. Application of this insight is critical to decision-making related to the planning and delivery of safe and appropriate patient-centred healthcare tailored to the needs of the individual. Provision for the necessary training is included in undergraduate programmes, but in the United Kingdom and Ireland there is considerable variation between centres without common outcomes. In 2009 representatives from 17 undergraduate dental schools in the United Kingdom and Ireland agreed to move towards a common, shared approach to meet their own immediate needs and that might also be of value to others in keeping with the Bologna Process. To provide a clear identity the term 'Clinical Medical Sciences in Dentistry' was agreed in preference to other names such as 'Human Disease' or 'Medicine and Surgery'. The group was challenged to define consensus outcomes. Contemporary dental education documents informed, but did not drive the process. The consensus curriculum for undergraduate Clinical Medical Sciences in Dentistry teaching agreed by the participating centres is reported. Many of the issues are generic and it includes elements that are likely to be applicable to others. This document will act as a focus for a more unified approach to the outcomes required by graduates of the participating centres and act as a catalyst for future developments that ultimately aim to enhance the quality of patient care.

Rotator cuff tears: what have we learned from animal models?

Rotator cuff tendon tears are among the most common soft tissue injuries that occur at the shoulder. Despite advancements in surgical repair techniques, rotator cuff repairs experience a high rate of failure. The common occurrence of tears and the frequency of re-tears require a further understanding of the mechanisms associated with injuries, healing, and regeneration of the rotator cuff. This paper reviews in vivo studies using the various animal shoulder models of the rat, rabbit, sheep, canine, and primate. These animal models have been used to study intrinsic and extrinsic factors leading to shoulder degeneration, various suture techniques, effects of post-surgical treatment, numerous biologic and synthetic scaffolds, and an assortment of biologic augmentations used to accelerate healing. These effects can be examined in a controlled manner using animal models without other confounding factors that sometimes limit clinical studies. The clinically impactful results will be explained to highlight the specific knowledge gained from using animal models in rotator cuff research.

Spironolactone reduces severity of obstructive sleep apnoea in patients with resistant hypertension: a preliminary report

Obstructive sleep apnoea (OSA) and hyperaldosteronism are very common in subjects with resistant hypertension. We hypothesized that aldosterone-mediated chronic fluid retention may influence OSA severity in patients with resistant hypertension. We tested this in an open-label evaluation by assessing the changes in the severity of OSA in patients with resistant hypertension after treatment with spironolactone. Subjects with resistant hypertension (clinical blood pressure (BP) >or=140/90 mm Hg on >or=3 antihypertensive medications, including a thiazide diuretic and OSA (defined as an apnoea-hypopnoea index (AHI) >or=15) had full diagnostic, polysomnography before and 8 weeks after spironolactone (25-50 mg a day) was added to their ongoing antihypertensive therapy. In all, 12 patients (mean age 56 years and body mass index 36.8 kg m(-2)) were evaluated. After treatment with spironolactone, the AHI (39.8+/-19.5 vs 22.0+/-6.8 events/h; P<0.05) and hypoxic index (13.6+/-10.8 vs 6.7+/-6.6 events/h; P<0.05), weight and clinic and ambulatory BP were significantly reduced. Plasma renin activity (PRA) and serum creatinine were significantly higher. This study provides preliminary evidence that treatment with a mineralocorticoid receptor antagonist substantially reduces the severity of OSA. If confirmed in a randomized assessment, it will support aldosterone-mediated chronic fluid retention as an important mediator of OSA severity in patients with resistant hypertension.

Isolated submandibular metastasis from a contralateral thyroid papillary microcarcinoma: an unusual case

Papillary carcinoma is the most common form of thyroid cancer. It is a relatively indolent disease, which commonly remains clinically silent until its incidental histological diagnosis in surgical material or at autopsy. A tumour less than 10 mm in size is termed a papillary microcarcinoma. Papillary microcarcinoma may present with clinical symptoms, most commonly jugulodigastric and pretracheal lymphadenopathy with or without palpable thyroid nodules. Isolated submandibular metastases are rare. We present the case of a submandibular metastasis arising from a solitary 3 mm papillary microcarcinoma of the thyroid on the contralateral side in a 46-year-old woman. We describe the ultrasound and MRI characteristics of the submandibular mass. The ultrasound findings in particular were suggestive of a thyroid malignancy and prompted detailed examination of the thyroid gland. Clinical and radiological examination of the thyroid was normal. To the best of our knowledge, we present the first report of a papillary microcarcinoma of the thyroid presenting as a contralateral and isolated submandibular mass.

Equivalent squares for small field dosimetry

The use of equivalent squares is of value when determining output and depth dose data for rectangular fields. We have looked at the variation with field shape of head scatter factors (S(c)), phantom scatter factors (S(p)) and tissue phantom ratios (TPRs) using measurements on a 6 MV linac with a Moduleaf mini-multileaf collimator. Measurements were made for fields with dimensions down to 1 cm. A different approach to calculating equivalent squares needs to be made depending on the quantity of interest. For TPRs, good agreement for rectangular fields can be obtained using the well established E = 2XY/(X+Y) formula where E is the equivalent square field size and X and Y are the field dimensions. For S(c) measurements, where a collimator exchange effect is observed, better agreement is obtained using E = (1+A)XY/(AX+Y), where A is an empirically determined constant. For S(p) measurements, E = 2XY/(X+Y) only gives agreement with measurements when the minimum field dimension is at least 2.5 cm. For smaller fields, the equivalent square overestimates S(p), with the difference being strongly related to the value of the smaller dimension. We propose an empirical formula, based on the size of the smaller dimension.

A radiotherapy technique to improve dose homogeneity around bone prostheses

Purpose. Following limb conserving surgery for bone or soft tissue sarcoma, patients may require post-operative radiotherapy to minimise the risk of local recurrence. In such circumstances the metal prosthesis reduces the dose in its shadow by approximately 10% when using opposed fields. We describe a technique to boost the underdosed area to overcome this problem.Patients or subjects. Seven sequential patients presenting between 1995 and 2001 had their treatment individualised because they had metal prosthesis in the treatment volume.Methods. To improve the target dose homogeneity we used a custom-made keyhole cutout to boost the area in the shadow of the prosthesis. The degree of attenuation caused by the metal prosthesis was estimated and a boost dose calculated. Exit thermoluminescent dosimetry (TLD) was used to confirm the estimates made.Results and discussion. Variation between patients was seen, demonstrating the need for exit TLD to individualise the treatment plan. The use of a boost field provides a method to overcome under-dosage in the shadow of a metal prosthesis. It improves dose homogeneity throughout the target volume and ensures adequate dose intensity around the prosthesis, the site most at risk of local recurrence.

Human papillomavirus and head and neck cancer: a systematic review and meta-analysis

It has been suggested that the link between human papillomavirus (HPV) and head and neck squamous cell carcinoma (HNSCC) is specific to carcinoma of the tonsil. We systematically reviewed studies that tested for HPV16 exposure in anatomically defined sites in the head and neck and a control group. The association between HPV16 and cancer was strongest for tonsil (OR: 15.1, 95% CI: 6.8-33.7), intermediate for oropharynx (OR: 4.3, 95% CI: 2.1-8.9) and weakest for oral (OR: 2.0, 95% CI: 1.2-3.4) and larynx (OR: 2.0, 95% CI: 1.0-4.2). To investigate heterogeneity, further stratification by method of HPV16 detection, suggested that variation in the magnitude of the HPV-cancer association with cancer site was restricted to studies using ELISA: among studies using PCR, the magnitude of the summary odds ratios was similar across the four sites. The association between HPV16 infection and HNSCC in specific sites suggests the strongest and most consistent association is with tonsil cancer, and the magnitude of this association is consistent with an infectious aetiology. However, the method of viral detection may be an important source of heterogeneity. Resolution of this issue will require further studies using both methods, examining associations separately in different sites.

Margins between clinical target volume and planning target volume for electron beam therapy

When growing a clinical target volume (CTV) to a planning target volume (PTV), it is necessary to determine suitable margins, based on the systematic and random uncertainties. For electron therapy, where treatments are usually given with single fields, the factors affecting the margin are very different in the direction of the incident beam from those in the perpendicular directions, since set-up errors do not affect the depth of the 90% isodose. For a typical case, the perpendicular margins are three times the margin in the direction of the incident beam. This gives rise to problems with volume growing algorithms if the beam axis is not aligned with a cardinal axis.

Palatability and glucose, insulin and satiety responses of chickpea flour and extruded chickpea flour bread eaten as part of a breakfast

OBJECTIVE

To determine the effect of adding chickpea flour or extruded chickpea flour to white bread on palatability and postprandial glycaemia, insulinaemia and satiety.

DESIGN

A randomised, single-blind, cross-over study of four 50 g available carbohydrate breakfasts.

SETTING

School of Exercise and Nutrition Sciences, Deakin University.

SUBJECTS

In all, 12 healthy subjects were recruited through posted notices. Totally, 11 (nine male, two female) completed the study (mean+/-s.e.m.; age 32+/-2 y; body mass index, 24.7+/-0.8 kg/m(2)).

INTERVENTION

After overnight fasting, subjects consumed a control (white) bread (WB) breakfast twice, a chickpea bread (CHB) breakfast once and an extruded chickpea bread (EXB) breakfast once. Palatability and postprandial blood glucose, insulin and satiety responses were determined. Following this, food intakes from an ad libitum buffet and for the remainder of the day were assessed.

RESULTS

A trend towards a lower incremental area under the curve (IAUC) of glucose for the CHB breakfast compared to the WB breakfast was observed (P=0.087). The IAUC of insulin and insulinaemic index (II) of the CHB breakfast were higher (P<0.05) than for the WB breakfast. No differences in glycaemic index (GI), satiety response, food intake or palatability were observed.

CONCLUSIONS

CHB and EXB demonstrated acceptable palatability. CHB demonstrated some hypoglycaemic effect compared to WB, but neither CHB nor EXB demonstrated effects on satiety or food intake. The hyperinsulinaemic effect of CHB observed in this study requires further investigation.

14-Azacamptothecin: A Potent Water-Soluble Topoisomerase I Poison

On the basis of an analysis of luotonin A and its D-ring deaza analogue as topoisomerase I poisons and topoisomerase I-dependent cytotoxic agents, a novel analogue of the structurally related antitumor antibiotic camptothecin (CPT) was prepared. 14-Azacamptothecin was found to have much greater aqueous solubility than CPT, to inhibit topoisomerase I-mediated DNA relaxation more efficiently than CPT, and to stabilize the covalent binary complex to almost the same extent. 14-Aza CPT was found to be slightly less active than CPT in mediating cytotoxicity toward yeast expressing human topoisomerase I, possibly as a consequence of its greater off-rate from the CPT-topoisomerase I-DNA ternary complex.