Post-Translational Modifications Control Phase Transitions of Tau

The self-assembly of Tau(297-391) into filaments, which mirror the structures observed in Alzheimer's disease (AD) brains, raises questions about the role of AD-specific post-translational modifications (PTMs) in the formation of paired helical filaments (PHFs). To investigate this, we developed a synthetic approach to produce Tau(291-391) featuring N-acetyllysine, phosphoserine, phosphotyrosine, and N-glycosylation at positions commonly modified in post-mortem AD brains, thus facilitating the study of their roles in Tau pathology. Using transmission electron microscopy (TEM), cryo-electron microscopy (cryo-EM), and a range of optical microscopy techniques, we discovered that these modifications generally hinder the in vitro assembly of Tau into PHFs. Interestingly, while acetylation's effect on Tau assembly displayed variability, either promoting or inhibiting phase transitions in the context of cofactor free aggregation, heparin-induced aggregation, and RNA-mediated liquid-liquid phase separation (LLPS), phosphorylation uniformly mitigated these processes. Our observations suggest that PTMs, particularly those situated outside the fibril's rigid core are pivotal in the nucleation of PHFs. Moreover, in scenarios involving heparin-induced aggregation leading to the formation of heterogeneous aggregates, most AD-specific PTMs, except for K311, appeared to decelerate the aggregation process. The impact of acetylation on RNA-induced LLPS was notably site-dependent, exhibiting both facilitative and inhibitory effects, whereas phosphorylation consistently reduced LLPS across all proteoforms examined. These insights underscore the complex interplay between site-specific PTMs and environmental factors in modulating Tau aggregation kinetics, enhancing our understanding of the molecular underpinnings of Tau pathology in AD and highlighting the critical role of PTMs located outside the ordered filament core in driving the self-assembly of Tau into PHF structures.

A survey in the West Midlands of the United Kingdom of current practice in managing hypotension in lower segment caesarean section under spinal anaesthesia

BACKGROUND

Spinal anaesthesia, the most common form of anaesthesia for caesarean section, leads to sympathetic blockade and profound maternal hypotension resulting in adverse maternal and neonatal outcomes. Hypotension, nausea and vomiting remain common but until the publication of the National Institute of Health and Care Excellence (NICE) 2021 guidance, no national guideline existed on how best to manage maternal hypotension following spinal anaesthesia for caesarean section. A 2017 international consensus statement recommended prophylactic vasopressor administration to maintain a systolic blood pressure of >90% of an accurate pre-spinal value, and to avoid a drop to <80% of this value. This survey aimed to assess regional adherence to these recommendations, the presence of local guidelines for management of hypotension during caesarean section under spinal anaesthesia, and the individual clinician's treatment thresholds for maternal hypotension and tachycardia.

METHODS

The West Midlands Trainee-led Research in Anaesthesia and Intensive Care Network co-ordinated surveys of obstetric anaesthetic departments and consultant obstetric anaesthetists across 11 National Health Service Trusts in the Midlands, England.

RESULTS

One-hundred-and-two consultant obstetric anaesthetists returned the survey and 73% of sites had a policy for vasopressor use; 91% used phenylephrine as the first-line drug but a wide range of recommended delivery methods was noted and target blood pressure was only listed in 50% of policies. Significant variation existed in both vasopressor delivery methods and target blood pressures.

CONCLUSIONS

Although NICE has since recommended prophylactic phenylephrine infusion and a target blood pressure, the previous international consensus statement was not adhered to routinely.

Body mass index associated differences in cardiac stress energetics in type 2 diabetes

Background

Patients with T2D and heart disease have normal body mass index (BMI), suggesting that diabetes and obesity mediate cardiovascular change by different mechanisms. Changes in cardiac energy metabolism in lean diabetic patients during exercise stress have not been previously reported.

Objectives

We aimed to assess if there are BMI-associated differences in cardiac stress metabolism in patients with T2D.

Methods

Twenty-five overweight T2D patients (O-T2D) and eleven lean T2D patients (LnT2D), age- and ethnicity-matched and with no other comorbidities were studied. Patients were on oral hypoglycaemics only and were free of diabetes complications. Participants underwent rest and dobutamine stress phosphorus magnetic resonance spectroscopy (31P-MRS) and cardiovascular magnetic resonance (CMR) at 3T for the assessment of myocardial phosphocreatine to ATP ratio (PCr/ATP) as a measure of myocardial energetics, biventricular volumes, rest and stress left ventricular (LV) ejection fraction, global longitudinal shortening, and mitral in-flow E/A ratio for assessment of diastolic function and perfusion.

Intravenous Dobutamine was administered at a dose of 10μg/kg/min, increasing at 90 second intervals up to a maximum of 40 μg/kg/min to achieve a target heart rate of 65% of the age-predicted maximal heart rate. Mean rate pressure product (RPP) was recorded at rest and stress. Heart rate was maintained at target for the duration of the 31P-MRS and stress CMR cine, mitral in-flow and perfusion acquisitions.

Results

The cardiac volumes, systolic or diastolic function and LV mass were similar between LnT2D and O-T2D. Although the O-T2D patients had a numerically lower rest and stress PCr/ATP ratio, this did not reach statistical significance. Resting PCr/ATP was reduced in LnT2D and O-T2D patients similarly. However, LnT2D showed a greater reduction in PCr/ATP (stress PCr/ATP LnT2D 1.51±0.2 vs O-T2D 1.41±0.25, p=0.02) despite similar increases in RPP. Stress myocardial blood flow (MBF) was also significantly lower in the O-T2D patients. There were significant correlations of BMI with LV mass (r=0.35, p=0.03); stress LVEF (r=−0.34, p=0.04); stress MBF stress (r=−0.53, p=0.001) and stress E/A (r=0.46, p=0.01) (figure 1).

Conclusions

Despite their better stress perfusion and similar glycaemic control, LnT2D show worse metabolic reserve characterised by more significant decrements in energetics in response to hemodynamic stress compared to overweight patients with T2D. Higher BMI correlates inversely with stress myocardial blood flow and with stress left ventricular ejection fraction. The presence of these subtle alterations in measures of stress metabolism and perfusion might signify a distinct metabolic phenotype of “lean diabetic cardiomyopathy”. Future studies are needed to further delineate alterations in cardiac energy metabolism in lean and overweight/obese type 2 diabetes patients, and their role in the development of cardiac dysfunction.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Wellcome TrustBHF

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

First Leptophobic Dark Matter Search from the Coherent-CAPTAIN-Mills Liquid Argon Detector

We report the first results of a search for leptophobic dark matter (DM) from the Coherent-CAPTAIN-Mills (CCM) liquid argon (LAr) detector. An engineering run with 120 photomultiplier tubes (PMTs) and 17.9×10^{20} protons on target (POT) was performed in fall 2019 to study the characteristics of the CCM detector. The operation of this 10-ton detector was strictly light based with a threshold of 50 keV and used coherent elastic scattering off argon nuclei to detect DM. Despite only 1.5 months of accumulated luminosity, contaminated LAr, and nonoptimized shielding, CCM's first engineering run has already achieved sensitivity to previously unexplored parameter space of light dark matter models with a baryonic vector portal. With an expected background of 115 005 events, we observe 115 005+16.5 events which is compatible with background expectations. For a benchmark mediator-to-DM mass ratio of m_{V_{B}}/m_{χ}=2.1, DM masses within the range 9  MeV≲m_{χ}≲50  MeV are excluded at 90% C. L. in the leptophobic model after applying the Feldman-Cousins test statistic. CCM's upgraded run with 200 PMTs, filtered LAr, improved shielding, and 10 times more POT will be able to exclude the remaining thermal relic density parameter space of this model, as well as probe new parameter space of other leptophobic DM models.

The Feasibility and User-Experience of a Digital Health Intervention Designed to Prevent Weight Gain in New Kidney Transplant Recipients—The ExeRTiOn2 Trial

Half of kidney transplant recipients (KTRs) gain more than 5% of their body weight in the first year following transplantation. KTRs have requested support with physical activity (PA) and weight gain prevention, but there is no routine care offered. There are few high-quality studies investigating the clinical value of diet, PA or combined interventions to prevent weight gain. The development and evaluation of theoretically informed complex-interventions to mitigate weight gain are warranted. The aims of this mixed-methods randomized controlled trial (RCT) were to explore the feasibility, acceptability and user-experience of a digital healthcare intervention (DHI) designed to prevent post-transplant weight gain, in preparation for a large multi-center trial. New KTRs (<3 months) with access to an internet compatible device were recruited from a London transplant center. The usual care (UC) group received standard dietary and PA advice. The intervention group (IG) received access to a 12-week DHI designed to prevent post-transplant weight gain. Primary feasibility outcomes included screening, recruitment, retention, adherence, safety and hospitalizations and engagement and experience with the DHI. Secondary outcomes (anthropometrics, bioimpedance, arterial stiffness, 6-minute walk distance and questionnaires) were measured at baseline, 3- and 12-months. 38 KTRs were screened, of which 32 (84.2%) were eligible, and of those 20 (62.5%) consented, with 17 participants (85%) completing baseline assessment (Median 49 years, 58.8% male, Median 62 days post-transplant). Participants were randomized using a computer-generated list (n = 9 IG, n = 8 UC). Retention at 12-months was 13 (76.4%) (n = 6 IG, n = 7 UC). All a priori progression criteria were achieved. There were no associated adverse events. Reflexive thematic analysis revealed four themes regarding trial participation and experience whilst using the DHI. Halting recruitment due to COVID-19 resulted in the recruitment of 40% of the target sample size. Mixed-methods data provided important insights for future trial design. A definitive RCT is warranted and welcomed by KTRs.

MO589: Exertion2 Trial: THE Weight Gain Prevention in Renal Transplant Online Study—a Randomized Controlled Feasibility Trial

BACKGROUND AND AIMS

Adverse weight gain within the first year of receiving a kidney transplant is associated with adverse health outcomes. Kidney transplant recipients (KTRs) have asked for support with physical activity and following healthy lifestyles. There is no recognised intervention to address weight gain prevention for new KTRs. Usability of an online intervention to prevent weight gain in new KTRs has recently been reported. The aim of this study was to examine the feasibility of undertaking a randomised controlled trial of an online intervention group (IG) compared with usual care UC) to address weight gain prevention in new KTRs.

METHOD

Participants were recruited from two south-London transplant sites, had a kidney transplant within 3 months, and had access to an internet compatible device. Exclusion criteria included history of an unstable medical condition, non-English speaking or <18 years. At baseline assessment participants were randomized to either UC or IG. The UC group received standard dietary and physical activity education. The IG received access to a 12-week password-protected website, weekly email reminders, and could contact the research physiotherapist via a secure message function.

Primary feasibility outcomes included screening rates, consent rates, adherence to study visits, acceptability of outcomes, engagement with the intervention, retention, willingness to be randomized, adverse events, hospitalizations, experience using the online intervention and experience taking part in the trial. Secondary outcomes were recorded at baseline, 3- and 12-months. These included body weight, body mass index (BMI), bioimpedance (BIA), pulse wave velocity (PWV), augmentation index (AI) and six-minute walk distance (6MWD).

RESULTS

Seventeen new KTRs (median age 49 years, 10 males, median 62 days post-transplant) were randomized to the IG (n = 9) or UC (n = 8). Screening rate was 84.2% (95% CI: 68.8–94.0), recruitment 62.5% (95% CI: 43.7–79.0) and intervention adherence at 12 months was 76.4% (95% CI: 50.0–93.2). All pre-set progression criteria for feasibility were achieved. There were no associated adverse events. Qualitative analysis revealed four themes; optimizing participation and recruitment, impact of Coronavirus disease 2019 (COVID-19), engagement is a choice (technical and personal factors) and mechanisms of action (assessment and intervention factors). The IG appeared to stabilize median body weight across the study; 94.5 kg, (IQR: 63.0, 102.0), 95.0 kg, (IQR: 66.7, 105.3) and 94.7 kg (IQR: 77.2, 117.3). Whereas UC participants increased [81.3 kg, (IQR: 73.6,94.6), 86.2 kg (75.4, 96.5) and 93.3 kg (70.3, 101.9)]. IG increased 6MWD [450 m, (IQR: 450, 540), 525 m (IQR: 472.5, 615) and 495 m (IQR: 465, 615)] and UC decreased 6MWD [517.5 m (IQR: 436, 570), 507.5 m (IQR: 442.5, 605) and 435 m (IQR 435, 555)]. All other outcomes were comparable across the sample.

CONCLUSION

Limitations include inadequate power and small sample size, and it was a single-centre study. Integrated mixed methods analysis demonstrate congruency of both qualitative and quantitative data. Participant attitudes, experiences and engagement with the study and intervention provide insight for future trial design. A future definitive trial is warranted and welcomed by KTRs.

A qualitative evaluation of participants experiences of living with back pain, lumbar fusion surgery, and post-operative rehabilitation

Background

The use of lumbar fusion surgery is increasing in developed economies. High levels of patient dissatisfaction are reported post-operatively. To address this need, we developed a theoretically informed rehabilitation programme for use following lumbar fusion surgery (the REFS programme). We conducted a mixed methods randomised controlled feasibility study (REFS v ‘usual care’). The numerical and feasibility outcomes are reported separately. The current qualitative study was ‘nested’ within the main feasibility study to explore participants’ experiences before and after lumbar fusion surgery including the impact of rehabilitation content. This facilitated a deeper understanding of potential mechanisms of action, for theoretical and programme refinement.

Methods

A purposive sample (n = 10 ‘usual care’, n = 10 REFS) was identified from the main feasibility study cohort. Individual semi-structured interviews were conducted post-operatively (median 8 months, range 5–11). Interview data were transcribed verbatim, coded, and analysed thematically.

Results

Three themes were constructed: the breadth and severity of impact associated with a chronic lumbar disorder was summarised in theme 1, ‘Ever-decreasing circles; living with a chronic lumbar disorder’. Theme 2, ‘What have I done? Reflections on recovery from lumbar fusion surgery’, illustrated participants post-operative helplessness, which was associated with worsening mental health, problematic use of opioids, fear related to the instillation of metalware, and the important mitigating effect of informal social support. Theme 3 ‘Rehabilitation experiences’ identified critical rehabilitation programme content including exercise, a shared rehabilitation experience, the opportunity for vicarious learning, and professional expertise.

Conclusions

To enhance patient benefit future REFS programme iterations should consider reinforcement of the identified valued programme content. Additional content should be considered to mitigate post-operative fear, which frequently aligned with the instillation of metalware into the spine. Participant’s perceptions regarding the necessity of lumbar fusion surgery has potential implications for the surgical consent process.

Trial registration

Study registration; ISRCTN60891364, date registered 10/7/2014.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-01050-y.

Cultural influences on physical activity and exercise beliefs in patients with chronic kidney disease: 'The Culture-CKD Study'-a qualitative study

OBJECTIVES

This study used a mixed-method approach to explore cultural and ethnic influences on the perception of, and decision to engage with or not to engage with, physical activity and exercise therapy in patients with chronic kidney disease (CKD).

DESIGN

Qualitative research was conducted through the use of semistructured interviews and focus groups. Self-reported physical activity levels were measured using the General Practice Physical Activity Questionnaire (GPPAQ), and self-efficacy for exercise with Bandura's Self-Efficacy for Exercise Scale.

SETTING

This study was conducted in a non-clinical setting of a single National Health Service Hospital Trust between April 2018 and July 2019.

PARTICIPANTS

Participants >18 years of age with a diagnosis of CKD, from black African, black Caribbean, South Asian or white ethnicity were eligible for the study. 84 patients with a diagnosis of CKD (stages 2-5), aged 25-79 (mean age 57) were recruited. Semistructured interviews (n=20) and six single-sex, ethnic-specific focus group discussions were undertaken (n=36).

OUTCOMES

Primary outcome was to explore the perceptions, attitudes and values about exercise and physical activity in different ethnic groups through qualitative interviews, analysed using an inductive thematic analysis approach. Questionnaires were analysed using Pearson correlation to determine if there was a significant relationship between the self-efficacy and GPPAQ levels.

RESULTS

Qualitative analysis provided four primary themes: I am who I am, Change of identity, Influences to physical activity and exercise and Support and education. Quantitative analysis using Pearson correlation revealed a significant correlation between GPPAQ levels of activity and self-efficacy to regulate exercise behaviour (r=-0.40, p=0.001).

CONCLUSION

Understanding the cultural, attitudes and beliefs of individuals with CKD from a variety of ethnic backgrounds is complex. Understanding of patients' experiences, thoughts and beliefs may be of relevance to clinicians when designing CKD exercise services.

TRIAL REGISTRATION NUMBER

NCT03709212; Pre-results.

A de novo paradigm for male infertility

De novo mutations are known to play a prominent role in sporadic disorders with reduced fitness. We hypothesize that de novo mutations play an important role in severe male infertility and explain a portion of the genetic causes of this understudied disorder. To test this hypothesis, we utilize trio-based exome sequencing in a cohort of 185 infertile males and their unaffected parents. Following a systematic analysis, 29 of 145 rare (MAF < 0.1%) protein-altering de novo mutations are classified as possibly causative of the male infertility phenotype. We observed a significant enrichment of loss-of-function de novo mutations in loss-of-function-intolerant genes (p-value = 1.00 × 10^-5) in infertile men compared to controls. Additionally, we detected a significant increase in predicted pathogenic de novo missense mutations affecting missense-intolerant genes (p-value = 5.01 × 10^-4) in contrast to predicted benign de novo mutations. One gene we identify, RBM5, is an essential regulator of male germ cell pre-mRNA splicing and has been previously implicated in male infertility in mice. In a follow-up study, 6 rare pathogenic missense mutations affecting this gene are observed in a cohort of 2,506 infertile patients, whilst we find no such mutations in a cohort of 5,784 fertile men (p-value = 0.03). Our results provide evidence for the role of de novo mutations in severe male infertility and point to new candidate genes affecting fertility.

Unilateral diaphragm paralysis with COVID-19 infection

Neurological complications are well described in SARS-CoV-2, but for the first time we report a case of unilateral diaphragm paralysis occurring early in mechanical ventilation for respiratory failure due to such an infection. The patient subsequently required tracheostomy and ventilator support for 37 days, and had increased breathlessness and an elevated diaphragm at clinic review 9 months later. Dynamic chest radiography demonstrated persistent diaphragm paralysis with an accompanying postural change in lung volumes, and he subsequently underwent surgical plication. This case demonstrates that although persistent dyspnoea is a common feature following SARS-CoV-2 infection and is usually due to deconditioning or persistent parenchymal involvement, it can be due to other causes and needs to be investigated appropriately.

The value of a consultant physiotherapist within a primary care musculoskeletal interface service: part of the spinal multidisciplinary team

Background/aims

The national low back pain pathway in the UK suggests practitioners managing patients with spinal pathology should be specifically trained to do so and have the ability to link with tertiary spinal services when required. The aim of this study was to ensure referrals through to a tertiary spinal surgical centre are appropriate and patients get the correct advice early in their management pathway.

Methods

A retrospective review of 700 cases were discussed at a spinal case-based discussion meeting in a primary care interface service, compared to services without this model. A convenience sample of cases were analysed with the consultant physiotherapist and those referred from other allied health professionals into the tertiary spinal surgical centre. Case-based team discussion took place before every referral into the tertiary spinal service, with spinal surgical discussion where required.

Results

Patients referred from other interface services were more likely to require further work-up such as investigations, or be discharged from clinic on their first attendance than those who had been through the case-based discussion.

Conclusions

A consultant physiotherapist working as part of the spinal team of a tertiary referral centre can help advanced practitioners with their clinical decision making to help prevent unnecessary referrals to spinal surgical services.

UK national and regional trends in cardiovascular magnetic resonance usage – the British Society of CMR survey results

Background

CMR is an imaging modality recommended for multiple indications. Access to CMR is a key issue for its clinical use. We surveyed all CMR units in the UK.

Methods

An online survey of CMR units in the UK, with responses analysed by region and compared with population data.

Results

Response rate was 100% (Table). The UK performed a total of 102,886 scans in 2017, and 117,967 in 2018 representing a 1-year 14.7% increase and a 10-year increase of 573% compared to 2008 data (20,597).By head of population in 2018 there were 1,776 CMR scans per million people, with significant variation nationally and regionally, e.g. 4,256 per million in London vs. 396 per million in Wales (Figure). Mean number of scans per unit was 1,404, (range 98–10,000) with wide variation in referral to diagnostic times (mean 45.7 days, range 5–180) (Figure).

Clinical indications for CMR were: heart failure 21%, cardiomyopathy 27%, function and viability 22%, stress 24%, vascular disease 5%, valvular 5%, myocarditis/pericardial 10%, paediatric /congenital 10%, others e.g. transplant/masses 4%, with overlap. There were 358 consultants reporting CMR in 2018 (234 (65%) cardiologists and 124 (35%) radiologists). 81% of units had a CMR service for patients with pacemakers and defibrillators.

Conclusion

The survey shows the state of CMR in the UK. The 10-year growth has been remarkable, but there are wide disparities in terms of use, access and wait times with potential implications for clinical care. Action is needed to make access equitable across the UK.

Figure 1

Funding Acknowledgement

Type of funding source: None

Stratifying the prognostic capability of cardiovascular magnetic resonance in severe aortic stenosis: a machine learning approach

Background

Cardiovascular magnetic resonance (CMR) demonstrates promise in improving patient risk stratification in aortic stenosis (AS). We explored whether machine learning might provide further insights into the prognostic capability of CMR parameters.

Methods

Severe AS patients (n=440) undergoing AVR were prospectively enrolled across 10 international sites, and CMR performed prior to AVR. A machine learning prediction model using a random survival forest (RSF) was trained with 29 variables, including 13 CMR, 4 echocardiography, and 12 clinical parameters, using post-AVR mortality as an outcome. The impact of the important variables on the outcome (partial dependency) was examined.

Results

The most predictive CMR parameters in the RSF model were the extracellular volume fraction (ECV%), followed by right ventricular ejection fraction (RVEF), late gadolinium enhancement (LGE%), and indexed left ventricular end-diastolic volume (LVEDVi). Regarding the partial effects, the predicted mortality increased strongly once the ECV% exceeded 26.5% (Figure 1A). The LGE% was associated with an increased risk of mortality, which reached a plateau beyond the level of 2% (Figure 1C). There were U-shaped relationships between mortality and both RVEF and LVEDVi, with the lowest mortality seen at RVEF 70% and LVEDVi 68ml/m2 (Figure 1B, D). These trends of predicted outcomes by each variable were verified in the Kaplan-Meier curves and Cox analyses (Table). In both Cox and RSF models, the predictability was substantially increased when these four CMR parameters were added to conventional clinical risk factors. An AS-CMR risk score comprised of these four parameters presented a stepwise increase in mortality with increasing adverse CMR features (p&lt;0.001).

Conclusions

Our machine learning analysis using RSF has identified ECV%, RVEF, LGE%, and LVEDVi as key prognostic markers in severe AS with a nonlinear influence of each parameter on mortality post-AVR.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study was supported by grants from the Korean Health Technology R & D Project, Ministry of Health, Welfare & Family Affairs, Republic of Korea (HI16C0225 and HI15C0399) and the National Institute for Health Research (NIHR) infrastructure at Leeds.

Usability and experience testing to refine an online intervention to prevent weight gain in new kidney transplant recipients

OBJECTIVES

Weight gain in the first year following kidney transplantation increases the risk of adverse health outcomes. Currently, there is no recognized intervention available to prevent weight gain after kidney transplantation. An online kidney transplant-specific resource, entitled Exercise in Renal Transplant Online (ExeRTiOn), has been co-created by a multi-professional team, including patients, to assist with weight prevention. This study aimed to evaluate patient and health care professional usability and experience of the ExeRTiOn online resource.

DESIGN

Qualitative study utilizing 'Think-Aloud' and semi-structured interviews.

METHODS

Participants (n = 17) were purposively sampled to include new kidney transplant recipients (n = 11) and transplant health care professionals (n = 6). Kidney transplant recipient participants were from a spread of physical activity levels based on scores from the General Practice Physical Activity Questionnaire (GPPAQ). 'Think-Aloud' interviews assessed the usability of ExeRTiOn. Semi-structured interviews explored participants' experience of ExeRTiOn, weight gain, and physical activity. The data set were analysed thematically. Participant characteristics, including login data and self-reported body weight, were collected.

RESULTS

Data analyses identified valued intervention content and usability aspects which were summarized by two themes. The first theme 'You need to know how to manage yourself' included subthemes: (1) the resource filled a guidance gap, (2) expert patient content resonated, and (3) the importance of goal setting and monitoring progress. The second theme 'room for improvement' included subthemes: (2) web support and (2) content and operational change suggestions.

CONCLUSIONS

Results have allowed for identification of potential areas for resource refinement. This has facilitated iterative enhancement of ExeRTiOn in preparation for a randomized controlled feasibility trial.

THU0342 DECLINE IN SUBCLINICAL SYSTEMIC SCLEROSIS PRIMARY HEART INVOLVEMENT ASSOCIATES WITH POOR PROGNOSTIC FACTORS AND ACTIVE INTERSTITIAL LUNG DISEASE

Background:

Primary systemic sclerosis heart involvement (pSSc-HI) is described in the majority of SSc patients when sensitive methods such as cardiovascular magnetic resonance (CMR) are used1. The natural history of these subclinical findings are unknown.

Objectives:

To evaluate for interval change in subclinical pSSc-HI, the association between change in CMR abnormalities and disease phenotype and whether disease modifying antirheumatic (DMARD) and/or vasodilator treatment influence the CMR course.

Methods:

SSc patients, fulfilling the 2013 ACR/EULAR criteria, with no cardiovascular (CV) disease, diabetes and no more than 2 CV risk factors had two CMRs performed (V1 & V2; minimum 1 year apart). A 3T CMR with late gadolinium enhancement (LGE), T1 mapping for extracellular volume (ECV of diffuse fibrosis) quantification and stress perfusion was undertaken.

Results:

31 SSc patients were evaluated, with median (IQR) follow up (between the 2 CMR scans) of 33 (17, 37) months. Median (IQR) age was 52 (47,60), 32% had diffuse cutaneous SSc, 52% interstitial lung disease (ILD), 29% Scl70+.

4/31 patients had a non-ischaemic LGE pattern suggesting focal fibrosis at V1, with no change in the pattern, distribution, or median (IQR) LGE scar mass between V1 and V2 [1.88 (1.01, 6.34) vs 1.70 (1.21, 4.18)]. At V2, 2 additional patients showed focal fibrosis, of which one had an episode of clinically diagnosed myocarditis. No significant change in ECV, T1 native, myocardial perfusion reserve (MPR) or left ventricle (LV) volumes and function were noted at V2 compared with V1 (p>0.01).

SSc patients with either increase in pre-existing LGE scar mass (n=1) or new fibrosis were all dcSSc, with ILD, 2 Scl70+. A reduction in forced vital capacity and total lung capacity associated with a reduction in LV ejection fraction (LVEF) (rho=0.413, p=0.021; rho-0.335, p=0.07) and MPR (rho=0.543, p=0.007; rho=0.627, p=0.002).

Patients receiving DMARD treatment had higher baseline LV end-diastolic volume compared to those with no DMARD treatment [mean (SD) 78 (19) vs 69 (10), p=0.167]. A decrease in LV stroke volume and an increase in T1 native at V1 vs V2 was noted for those on DMARD [mean (SD) 49 (8) vs 46 (8), p =0.023; 1208 (65) vs 1265 (56), p=0.008 respectively] (Figure 1). No significant change in CMR measures in those receiving vasodilator or angiotensin-converting-enzyme inhibitor treatment was noted (p>0.01).

Figure 1.

Mean (SD) of T1 native, LVSV/BSA, LVEF, and LVEDV/BSA at V1 compared to V2 in those with and without DMARD treatment. BSA, body surface area; DMARD, disease modifying antirheumatic drugs; EDV, end-diastolic volume; SV, stroke volume; LV left ventricular; EF, ejection fraction.

Conclusion:

This first, pilot longitudinal study of CMR-defined subclinical pSSc-HI suggests largely stable appearances with follow-up. Progression of new focal fibrosis and decline in LV function and MPR, where observed, associated with poor prognostic factors of SSc and ILD progression. Consistent with this, individuals on DMARD appeared to show interval decline. Larger longitudinal studies are warranted to confirm these findings and inform on utility of CMR monitoring of subclinical pSSc-HI in poor prognosis SSc.

References:

[1]Ntusi NA et al, J Cardiovasc Magn Reson. 2014

Disclosure of Interests:

Raluca-Bianca Dumitru: None declared, Lesley Anne Bissell: None declared, Bara Erhayiem: None declared, Graham Fent: None declared, Ananth Kidambi: None declared, Giuseppina Abignano: None declared, John Greenwood: None declared, John Biglands: None declared, Francesco Del Galdo: None declared, Sven Plein: None declared, Maya H Buch Grant/research support from: Pfizer, Roche, and UCB, Consultant of: Pfizer; AbbVie; Eli Lilly; Gilead Sciences, Inc.; Merck-Serono; Sandoz; and Sanofi

The ORNATE India Project: United Kingdom-India Research Collaboration to tackle visual impairment due to diabetic retinopathy

INTRODUCTION

The ORNATE India project is funded by the UK Research and Innovation (UKRI) through the Global Challenges Research Fund. The aim is to build research capacity and capability in India and the UK to tackle global burden of diabetes-related visual impairment. As there are over 77 million people with diabetes in India, it is challenging to screen every person with diabetes annually for sight-threatening diabetic retinopathy (DR). Therefore, alternate safe approaches need to be developed so that those at-risk of visual impairment due to DR is identified promptly and treated.

METHODS

The project team utilised diverse global health strategies and research methods to co-design work packages to build research capacity and capability to ensure effective, affordable and efficient DR services are made available for the population. The strategies and methods employed included health system strengthening; implementation science; establishing care pathways; co-designing collaborative studies on affordable technologies, developing quality standards and guidelines to decrease variations in care; economic analysis; risk modelling and stratification. Five integrated work packages have been developed to deal with all aspects of DR care. These included implementation of a DR screening programme in the public health system in a district in Kerala, evaluating regional prevalence of diabetes and DR and assessing ideal tests for holistic screening for diabetes and its complications in 20 areas in India, utilising artificial intelligence on retinal images to facilitate DR screening, exploring biomarker and biosensor research to detect people at risk of diabetes complications, estimating cost of blindness in India and risk modelling to develop risk-based screening models for diabetes and its complications. A large collaborative network will be formed to propagate research, promote shared learning and bilateral exchanges between high- and middle-income countries to tackle diabetes-related blindness.

P2707Invasive coronary physiology during primary percutaneous coronary intervention in patients treated with intracoronary alteplase or placebo: the double-blind T-TIME physiology substudy

Background

Impaired microcirculatory reperfusion worsens prognosis post-primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). Intracoronary (IC) alteplase targets persisting thrombus post-reperfusion & distal embolisation. In the T-TIME trial microvascular obstruction on cardiac magnetic resonance (CMR) did not differ with IC alteplase vs placebo.

Purpose

To prospectively determine if index of microcirculatory resistance (IMR) is lower & coronary flow reserve (CFR) or resistive reserve ratio (RRR) are higher (improved) with IC alteplase, & to provide mechanistic insights.

Methods

A pre-planned substudy of the main protocol. From 2016–2017, STEMI patients from 3 UK hospitals ≤6 hrs ischaemic time were randomised in a 1:1:1 dose-ranging, double-blind design. Following standard care reperfusion, alteplase (10 or 20mg) or placebo was infused over 5–10 mins proximal to the culprit lesion pre-stenting. IMR (primary outcome), CFR & RRR (secondary outcomes) were measured in the culprit artery post-PCI. Physiology results were obscured from clinicians acquiring the data, to maintain blinding. CMR was performed 2 days & 3 months post-STEMI. Subgroup analyses were prespecified including by ischaemic time (<2 hours, 2–4 hrs, >4 hrs) & IMR threshold >32.

Results

In 144 patients (mean age 59 yrs, 80% male), IMR, CFR or RRR post-PCI did not differ with alteplase vs placebo (Table). Patients with ischaemic time <2 hrs had a dose related increase in CFR (placebo 1.2 [IQR 1.1–1.7], alteplase 10mg 1.4 [IQR 1.0–1.8], alteplase 20mg 2.0 [IQR 1.8–2.3] p=0.01 for interaction) & RRR (placebo 1.5 [IQR 1.3–1.9], alteplase 10mg 1.6 [1.1–2.2], alteplase 20mg 2.2 [2.0–2.6], p=0.03 for interaction). In subjects with post-PCI IMR>32, % ST-resolution at 60 mins was worse with alteplase 10mg vs placebo (23.1±53.9 vs 50.9±31.5) & in those with IMR≤32% ST-resolution at 60 mins was better with alteplase 20mg vs placebo (68.0±30.7 vs 39.1±43.2), p=0.002 for interaction. The CMR findings in the substudy & overall trial populations were consistent.

Main results Placebo Alteplase 10mg Alteplase 20mg (n=53) (n=41) (n=50) IMR, median (IQR) 33.0 (17.0–57.0) 22.0 (17.0–42.0) 37.0 (20.0–57.8) p=0.15 p=0.78 CFR, median (IQR) 1.3 (1.1–1.8) 1.4 (1.1–1.9) 1.5 (1.1–2.0) p=0.92 p=0.74 RRR, median (IQR) 1.6 (1.3–2.2) 1.6 (1.4–2.6) 1.8 (1.3–2.4) p=0.69 p=0.81 P-values for comparison of alteplase with placebo.

Conclusions

In acute STEMI with ischaemic time ≤6 hrs, IMR, CFR or RRR post-PCI did not differ with alteplase vs placebo. In those with shorter ischaemic times (<2 hrs) CFR & RRR, but not IMR, were improved with alteplase. We observed interactions between alteplase dose, ischaemic time & mechanisms of effect.

Acknowledgement/Funding

Dr Maznyczka is funded by a fellowship from the British Heart Foundation (FS/16/74/32573). T-TIME was funded by grant 12/170/4 from NIHR-EME

Charge migration in photo-ionized aromatic amino acids

Attosecond pump-probe spectroscopy is a unique tool for the direct observation of the light-activated electronic motion in molecules and it offers the possibility to capture the first instants of a chemical reaction. Recently, advances in attosecond technology allowed the charge migration processes to be revealed in biochemically relevant molecules. Although this purely electronic process might be key for a future chemistry at the electron time scale, the influence of this ultrafast charge flow on the reactivity of a molecule is still debated. In this work, we exploit extreme ultraviolet attosecond pulses to activate charge migration in two aromatic amino acids, namely phenylalanine and tryptophan. Advanced numerical calculations are performed to interpret the experimental data and to discuss the effects of the nuclear dynamics on the activated quantum coherences. By comparing the experimental results obtained in the two molecules, we show that the presence of different functional groups strongly affects the fragmentation pathways, as well as the charge rearrangement. The observed charge dynamics indeed present peculiar aspects, including characteristic periodicities and decoherence times. Numerical results indicate that, even for a very large molecule such as tryptophan, the quantum coherences can survive the nuclear dynamics for several femtoseconds. These results open new and important perspectives for a deeper understanding of the photo-induced charge dynamics, as a promising tool to control the reactivity of bio-relevant molecules via photo-excitation. This article is part of the theme issue 'Measurement of ultrafast electronic and structural dynamics with X-rays'.

TP1-11 MS-STAT2: a phase 3 trial of high dose simvastatin in secondary progressive multiple sclerosis

Objectives

Disease modifying treatment for secondary progressive multiple sclerosis (SPMS) represents a major unmet need. We outline here the rationale for the MS-STAT2 trial – a phase 3 study of simvastatin in decreasing clinical progression in SPMS. MS-STAT2 will be a landmark study not only for patients with SPMS, but also for the area of drug repurposing and academically led clinical trials as a whole.

Design

Multicentre, double blind, parallel group randomised placebo-controlled trial. It follows the positive outcome from the phase 2 MS-STAT1 trial, which demonstrated a 43% reduction in the annualised rate of brain atrophy compared to placebo.1

Subjects

1180 patients with SPMS with an expanded disability status scale (EDSS) score of 4.0–6.5. Patients need to show evidence of disease progression over the preceding 2 years.

Methods

Subject will be recruited at 28 sites across the UK, and randomised to simvastatin 80 mg or matched placebo and assessed every 6 months over the 3 year trial.

Results

The primary outcome measure is time to 6 month confirmed disability progression, based on change in Expanded Disability Status Scale (EDSS) scores compared to baseline. Secondary outcomes include assessments of cognition, walking, upper limb function and vision. Sub-studies will include advanced imaging outcomes, ocular coherence tomography and fluid biomarkers.

Conclusions

MS-STAT2 is set to be a pivotal trial for SPMS. Recruitment has now commenced and further sites are welcome.

Reference

Chataway J, et al. MS-STAT. Lancet2014;383:2213–21.

Protein Contamination of the Laryngeal Mask Airway and its Relationship to Re-use

The Laryngeal Mask Airway is a reusable device for maintaining the patency of a patient's airway during general anaesthesia. The device can be reused after it has been cleaned and sterilized. Protein contamination of medical instruments is a concern and has been found to occur despite standard sterilization techniques. The reason for the concern relates to the possibility of the transmission of prions and the risk of developing a neurodegenerative disorder such as Creutzveldt-Jacob disease. The purpose of this study was to quantify the amount of protein contamination that occurs, and to relate this to the number of times the Laryngeal Mask Airway has been used. Fifty previously used Classic Laryngeal Masks were collected after routine sterilization and packaging. The devices were immersed in protein detecting stain and then visual inspection performed to assess the degree and distribution of the staining. The researcher was blinded to the number of times the Laryngeal Mask Airway had been used. Linear regression analysis of the degrees of staining of the airway revealed that protein contamination occurs after the first use of the device and this increases with each subsequent use. This finding highlights the concern that the currently used cleaning and sterilization methods do not prevent the accumulation of proteinaceous material on Laryngeal Mask Airways. Consideration should be given to the search for more efficient cleaning and sterilization techniques or the use of disposable devices.

Ease of use of tobramycin inhalation powder compared with nebulized tobramycin and colistimethate sodium: a crossover study in cystic fibrosis patients with pulmonary Pseudomonas aeruginosa infection

Background:

This study assessed the ease of use of tobramycin inhalation powder (TIP) administered via T-326 inhaler versus tobramycin inhalation solution (TIS) and colistimethate sodium (COLI), both administered via nebulizers, for the treatment of chronic pulmonary Pseudomonas aeruginosa infection in patients with cystic fibrosis (CF).

Methods:

A real-world, open-label, crossover, interventional phase IV study was conducted in CF patients aged ⩾6 years with forced expiratory volume in 1 second (FEV₁) ⩾25% to ⩽90% predicted. Patients were assigned to one of the three treatment arms in Cycle 1; all patients received TIP in Cycle 2. Each cycle consisted of 28 days on and 28 days off the treatment.

Results:

A total of 60 patients [mean (standard deviation) age, 27.6 (8.4) years] were allocated to three treatment arms [TIS/TIP (n = 14); COLI/TIP (n = 28); TIP/TIP (n = 18)] in Cycle 1. The mean total administration time, which included device setup and cleaning, in Cycle 1 versus Cycle 2 for TIS/TIP, COLI/TIP, and TIP/TIP arms were 37.0 versus 5.0 min, 16.4 versus 3.8 min, and 4.2 versus 3.4 min, respectively. The difference in mean total administration time was significantly shorter in Cycle 2 than in Cycle 1 for TIS/TIP (p = 0.0112) and COLI/TIP (p = 0.0016) arms. Overall, 12 patients were found to have contaminated devices across the two treatment cycles. In the TIP/TIP arm, no contamination of the T-326 inhaler was observed in either cycle. Treatment satisfaction, assessed by the Treatment Satisfaction Questionnaire for Medication and ACCEPT® questionnaire, was better overall for TIP compared with TIS and COLI. There were no unexpected adverse events and most were mild or moderate in intensity.

Conclusion:

The T-326 inhaler used to deliver TIP was easy to use, required shorter total administration time, and was much less frequently contaminated than the nebulizers. The safety findings observed for TIP were generally consistent with its established safety profile.

Abstract P3-06-04: Bcl-2 functional converters inhibit tumor growth and metastatic potential in zebrafish xenografts

While potential therapies might have pronounced success in the simplified settings in cell culture medium, many drugs fail or underperform when cancer cells are encased in a complex 3D microenvironment. Although, rat and mouse models will continue to be the gold standard for in vivo data in drug discovery, zebrafish xenograft models have emerged as a powerful model that can quickly and efficiently deliver in vivo drug efficacy data before commitment to expensive and time consuming rodent models. We have discovered several compounds that work as B-cell lymphoma 2 (Bcl-2) functional converters and activate Bcl-2 into a killer instead of its native anti-apoptotic role. In this study, we use a zebrafish xenograft model to evaluate the ability of these compounds to inhibit xenograft tumor growth of Bcl-2 expressing cancer cells, including triple negative breast cancers. Live fluorescent imaging of cancer cells within zebrafish embryos revealed a decrease in cancer cell growth while under treatment of compounds. Furthermore, the agents that converted Bcl-2 into pro-apoptotic protein also inhibited the metastatic potential of the cancer cells. Therefore, this study demonstrates zebrafish xenograft techniques that can be used to quickly and efficiently obtain in vivo drug discovery data. Moreover, we report novel Bcl-2 functional converter compounds that can effectively reduce xenograft tumor growth and its ability to invade tissue in a living 3D environment and establish the role of Bcl-2 in cancer progression.

Citation Format: Gamble J, Pearce M, Kopparapu P, Jang HS, Tanguay R, Greenwood J, Kolluri S. Bcl-2 functional converters inhibit tumor growth and metastatic potential in zebrafish xenografts [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-06-04.

Development of a Low Toxicity PMR-type Polyimide for Advanced Composite Applications

The thermosetting polyimide, PMR-15, is the leading contender for use in polymer matrix composites intended for high temperature applications. Although the properties of PMR-15 are generally good, its widespread use in aircraft and aeroengines has been hampered by a number of drawbacks. Among these are microcracking due to thermal cycling, irreproducibility of processing and the toxicity of the methylene diamine comonomer. The aim of the work reported here was to develop a PMR-type polyimide with properties equivalent to conventional PMR-15 but with none of the drawbacks. A key target of the work was to reduce the hazards associated with the use of methylene dianiline (MDA). Consequently, much of the work involved screening formulations in which MDA was replaced by a diamine of reduced toxicity. One formulation, coded B1, has been identified of which initial results look extremely promising. This formulation uses a partially fluorinated, four-ring diamine of low toxicity. This material was synthesized in-house and subsequently scaled-up in a semi-commercial process. Prepreg was manufactured on commercial equipment. Cure cycles were developed using mechanical spectrometry (RDS). Laminates were made by autoclave molding, and mechanical properties before and after high temperature ageing were determined. Preliminary results show that the B1 formulation compares favorably with conventional PMR-15.

Evaluating rehabilitation following lumbar fusion surgery (REFS): study protocol for a randomised controlled trial

Background

The rate of lumbar fusion surgery (LFS) is increasing. Clinical recovery often lags technical outcome. Approximately 40 % of patients undergoing LFS rate themselves as symptomatically unchanged or worse following surgery. There is little research describing rehabilitation following LFS with no clear consensus as to what constitutes the optimum strategy. It is important to develop appropriate rehabilitation strategies to help patients manage pain and recover lost function following LFS.

Methods/design

The study design is a randomised controlled feasibility trial exploring the feasibility of providing a complex multi-method rehabilitation intervention 3 months following LFS. The rehabilitation protocol that we have developed involves small participant groups of therapist led structured education utilising principles of cognitive behavioral therapy (CBT), progressive, individualised exercise and peer support. Participants will be randomly allocated to either usual care (UC) or the rehabilitation group (RG). We will recruit 50 subjects, planning to undergo LFS, over 30 months. Following LFS all participants will experience normal care for the first 3 months. Subsequent to a satisfactory 3 month surgical review they will commence their allocated post-operative treatment (RG or UC). Data collection will occur at baseline (pre-operatively), 3, 6 and 12 months post-operatively. Primary outcomes will include an assessment of feasibility factors (including recruitment and compliance). Secondary outcomes will evaluate the acceptability and characteristics of a limited cluster of quantitative measures including the Oswestry Disability Index (ODI) and an aggregated assessment of physical function (walking 50 yards, ascend/descend a flight of stairs). A nested qualitative study will evaluate participants’ experiences.

Discussion

This study will evaluate the feasibility of providing complex, structured rehabilitation in small groups 3 months following technically successful LFS. We will identify strengths and weakness of the proposed protocol and the usefulness and characteristics of the planned outcome measures. This will help shape the development of rehabilitation strategies and inform future work aimed at evaluating clinical efficacy.

Trial registration

ISRCTN60891364, 10/07/2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0751-9) contains supplementary material, which is available to authorized users.