Measurement of fibre fracture toughness using an alternative specimen geometry

This paper presents an experimental and numerical study focused on the tensile fibre fracture toughness characterisation of hybrid plain weave composite laminates using non-standardized Overheight Compact Tension (OCT) specimens. The position as well as the strain field ahead of the crack tip in the specimens was determined using a digital speckle photogrammetry system. The limitation on the applicability of standard data reduction schemes for the determination of the intralaminar fibre fracture toughness of composites is presented and discussed. A methodology based on the numerical evaluation of the strain energy release rate using the J-integral method is proposed to derive new geometric correction functions for the determination of stress intensity factor for alternative composite specimen geometries. A comparison between different methods currently available to compute the intralaminar fracture toughness in composites is also presented and discussed. Good agreement between numerical and experimental results using the proposed methodology was obtained.

Hypofractionated radiotherapy versus conventionally fractionated radiotherapy for patients with intermediate-risk localised prostate cancer: 2-year patient-reported outcomes of the randomised, non-inferiority, phase 3 CHHiP trial

BACKGROUND: Patient-reported outcomes (PROs) might detect more toxic effects of radiotherapy than do clinician-reported outcomes. We did a quality of life (QoL) substudy to assess PROs up to 24 months after conventionally fractionated or hypofractionated radiotherapy in the Conventional or Hypofractionated High Dose Intensity Modulated Radiotherapy in Prostate Cancer (CHHiP) trial.

METHODS: The CHHiP trial is a randomised, non-inferiority phase 3 trial done in 71 centres, of which 57 UK hospitals took part in the QoL substudy. Men with localised prostate cancer who were undergoing radiotherapy were eligible for trial entry if they had histologically confirmed T1b-T3aN0M0 prostate cancer, an estimated risk of seminal vesicle involvement less than 30%, prostate-specific antigen concentration less than 30 ng/mL, and a WHO performance status of 0 or 1. Participants were randomly assigned (1:1:1) to receive a standard fractionation schedule of 74 Gy in 37 fractions or one of two hypofractionated schedules: 60 Gy in 20 fractions or 57 Gy in 19 fractions. Randomisation was done with computer-generated permuted block sizes of six and nine, stratified by centre and National Comprehensive Cancer Network (NCCN) risk group. Treatment allocation was not masked. UCLA Prostate Cancer Index (UCLA-PCI), including Short Form (SF)-36 and Functional Assessment of Cancer Therapy-Prostate (FACT-P), or Expanded Prostate Cancer Index Composite (EPIC) and SF-12 quality-of-life questionnaires were completed at baseline, pre-radiotherapy, 10 weeks post-radiotherapy, and 6, 12, 18, and 24 months post-radiotherapy. The CHHiP trial completed accrual on June 16, 2011, and the QoL substudy was closed to further recruitment on Nov 1, 2009. Analysis was on an intention-to-treat basis. The primary endpoint of the QoL substudy was overall bowel bother and comparisons between fractionation groups were done at 24 months post-radiotherapy. The CHHiP trial is registered with ISRCTN registry, number ISRCTN97182923.

FINDINGS: 2100 participants in the CHHiP trial consented to be included in the QoL substudy: 696 assigned to the 74 Gy schedule, 698 assigned to the 60 Gy schedule, and 706 assigned to the 57 Gy schedule. Of these individuals, 1659 (79%) provided data pre-radiotherapy and 1444 (69%) provided data at 24 months after radiotherapy. Median follow-up was 50·0 months (IQR 38·4-64·2) on April 9, 2014, which was the most recent follow-up measurement of all data collected before the QoL data were analysed in September, 2014. Comparison of 74 Gy in 37 fractions, 60 Gy in 20 fractions, and 57 Gy in 19 fractions groups at 2 years showed no overall bowel bother in 269 (66%), 266 (65%), and 282 (65%) men; very small bother in 92 (22%), 91 (22%), and 93 (21%) men; small bother in 26 (6%), 28 (7%), and 38 (9%) men; moderate bother in 19 (5%), 23 (6%), and 21 (5%) men, and severe bother in four (<1%), three (<1%) and three (<1%) men respectively (74 Gy vs 60 Gy, ptrend=0.64, 74 Gy vs 57 Gy, ptrend=0·59). We saw no differences between treatment groups in change of bowel bother score from baseline or pre-radiotherapy to 24 months.

INTERPRETATION: The incidence of patient-reported bowel symptoms was low and similar between patients in the 74 Gy control group and the hypofractionated groups up to 24 months after radiotherapy. If efficacy outcomes from CHHiP show non-inferiority for hypofractionated treatments, these findings will add to the growing evidence for moderately hypofractionated radiotherapy schedules becoming the standard treatment for localised prostate cancer.

FUNDING: Cancer Research UK, Department of Health, and the National Institute for Health Research Cancer Research Network.

Utilisation of a novel ProteaseTag™ activity immunoassay for the specific measurement of neutrophil elastase in BAL from children with cystic fibrosis

Introduction: Neutrophil elastase (NE) is a serine protease implicated in the pathogenesis of several respiratory diseases including cystic fibrosis (CF). The presence of free NE in BAL is a predictor of subsequent bronchiectasis in children with CF (Sly et al, 2013, NEJM 368: 1963-1970). Furthermore, children with higher levels of sputum NE activity (NEa) tend to experience a more rapid decline in FEV1 over time even after adjusting for age, gender and baseline FEV1 (Sagel et al, 2012, AJRCCM 186: 857-865). Its detection and quantification in biological samples is however confounded by a lack of robust methodologies. Standard assays using chromogenic or fluorogenic substrates are not specific when added to complex samples containing multiple proteolytic and hydrolytic enzymes. ELISA systems measure total protein levels which can be a mixture of latent, active and protease-inhibitor complexes. We have therefore developed a novel assay (ProteaseTag™ Active NE Immunoassay), which couples an activity dependent NE-Tag with a specific antibody step, resulting in an assay which is both selective and specific for NEa. Aims: To clinically validate ProteaseTag™ Active NE for the detection of free NEa in BAL from children with CF. Methods: A total of 95 paediatric BAL samples [CF (n=76; 44M, 32F) non-CF (n=19; 12M, 7F)] collected through the Study of Host Immunity and Early Lung Disease in CF (SHIELD CF) were analysed for NEa using ProteaseTag™ Active NE (ProAxsis Ltd) and a fluorogenic substrate-based assay utilising Suc-AAPV-AMC (Sigma). IL-8 was measured by ELISA (R&D Systems). Results were analysed to show comparisons in free NEa between CF and non-CF samples alongside correlations with a range of clinical parameters. Results: NEa measured by ProteaseTag™ Active NE correlated significantly with age (r=0.3, p=0.01) and highly significantly with both IL-8 (r=0.4, p=<0.0001) and the absolute neutrophil count (ANC) (r=0.4, p=<0.0001). These correlations were not observed when NEa was measured by the substrate assay even though a significant correlation was found between the two assays (r=0.8, p<0.0001). A trend towards significance was found between NEa in the CF and non-CF groups when measured by ProteaseTag™ Active NE (p=0.07). Highly significant differences were found with the other inflammatory parameters between the 2 groups (IL-8: p=0.0002 and ANC: p=0.006). Conclusion: NEa as a primary efficacy endpoint in clinical trials or as a marker of inflammation within the clinic has been hampered by the lack of a robust and simple to use assay. ProteaseTag™ Active NE has been shown to be a specific and superior tool in the measurement of NEa in paediatric CF BAL samples (supporting data from previous studies using adult CF expectorated samples). The technology is currently being transferred to a lateral flow device for use at Point of Care. Acknowledgements: This work was supported by the National Children’s Research Centre, Dublin (SHIELD CF) and grants from the Medical Research Council and Cystic Fibrosis Foundation Therapeutics.

Community dynamics and the lower airway microbiota in stable chronic obstructive pulmonary disease, smokers and healthy non-smokers

RATIONALE: The role bacteria play in the progression of COPD has increasingly been highlighted in recent years. However, the microbial community complexity in the lower airways of patients with COPD is poorly characterised.

OBJECTIVES: To compare the lower airway microbiota in patients with COPD, smokers and non-smokers.

METHODS: Bronchial wash samples from adults with COPD (n=18), smokers with no airways disease (n=8) and healthy individuals (n=11) were analysed by extended-culture and culture-independent Illumina MiSeq sequencing. We determined aerobic and anaerobic microbiota load and evaluated differences in bacteria associated with the three cohorts. Culture-independent analysis was used to determine differences in microbiota between comparison groups including taxonomic richness, diversity, relative abundance, 'core' microbiota and co-occurrence.

MEASUREMENT AND MAIN RESULTS: Extended-culture showed no difference in total load of aerobic and anaerobic bacteria between the three cohorts. Culture-independent analysis revealed that the prevalence of members of Pseudomonas spp. was greater in the lower airways of patients with COPD; however, the majority of the sequence reads for this taxa were attributed to three patients. Furthermore, members of Bacteroidetes, such as Prevotella spp., were observed to be greater in the 'healthy' comparison groups. Community diversity (α and β) was significantly less in COPD compared with healthy groups. Co-occurrence of bacterial taxa and the observation of a putative 'core' community within the lower airways were also observed.

CONCLUSIONS: Microbial community composition in the lower airways of patients with COPD is significantly different to that found in smokers and non-smokers, indicating that a component of the disease is associated with changes in microbiological status.