Graded Quasiperiodic Metamaterials Perform Fractal Rainbow Trapping

The rainbow trapping phenomenon of graded metamaterials can be combined with the fractal spectra of quasiperiodic waveguides to give a metamaterial that performs fractal rainbow trapping. This is achieved through a graded cut-and-project algorithm that yields a geometry for which the effective projection angle is graded along its length. As a result, the fractal structure of local band gaps varies with position, leading to broadband "fractal" rainbow trapping. We demonstrate this principle by designing an acoustic waveguide, which is characterised using theory, simulation and experiments.

Investigating blood alcohol concentrations in injury- related deaths before and during the COVID-19 national lockdown in Western Cape Province, South Africa: A cross-sectional retrospective review

BACKGROUND

Alcohol is a significant contributor to injury-related morbidity and mortality in South Africa (SA). During the COVID-19global pandemic, restrictions to movement and to legal access to alcohol (i.e. ethanol) were introduced in SA.

OBJECTIVES

To investigate the effect of alcohol bans during the COVID-19 lockdown periods on injury-related mortality and blood alcoholconcentrations (BACs) in these deaths.

METHODS

A retrospective, cross-sectional analysis of injury-related deaths in Western Cape Province (WC), SA, between 1 January 2019 and31 December 2020 was conducted. Cases where BAC testing was performed were further examined according to the periods of lockdownand alcohol restrictions.

RESULTS

A total of 16 027 injury-related cases were admitted to Forensic Pathology Service mortuaries in the WC over the 2-year period. Anaverage decrease of 15.7% injury-related deaths in 2020 compared with 2019 was noted, as well as a 47.7% decrease in injury-related deathsduring hard lockdown (April - May 2020) compared with the same period in 2019. In the injury-related deaths, 12 077 (75.4%) had bloodspecimens collected for BAC testing. In 5 078 (42.0%) of submitted cases, a positive BAC (≥0.01 g/100 mL) was reported. No significantdifference was observed in the mean positive BAC between 2019 and 2020. However, in April and May 2020, the mean BAC observed(0.13 g/100 mL) was less than that in 2019 (0.18 g/100 mL). A high number of positive BACs in the 12- 17-year age group (23.4%) was observed.

CONCLUSION

There was a clear decrease in injury-related deaths in the WC during the COVID-19-related lockdown periods, whichcoincided with the alcohol ban and restriction of movement, and an increase following relaxation of restrictions on alcohol sales andmovement. The data illustrate that mean BACs were similar between all periods of alcohol restriction compared with 2019, apart from hardlockdown in April - May 2020. This coincided with a smaller mortuary intake during the level 5 and 4 lockdown periods.

Investigating blood alcohol concentrations in injury-related deaths before and during the COVID-19 National lockdown in Western Cape, South Africa: A cross-sectional retrospective review

BACKGROUND

Alcohol is a significant contributor to injury-related morbidity and mortality in South Africa (SA).  During the COVID-19 global pandemic, restrictions to movement and to the legal access of alcohol* were introduced in SA.  This study aimed to investigate the effect of alcohol bans during the COVID-19 lockdown periods on injury-related mortality and the blood alcohol concentrations (BAC) in these deaths.

METHODS

A retrospective, cross-sectional analysis of injury-related deaths in Western Cape (WC) province, SA, between 1 January 2019 to 31 December 2020 was conducted. Cases where BAC testing was performed were further examined according to the periods of lockdown (AL5-1) and alcohol restrictions.

RESULTS

A total of 16,027 injury-related cases were admitted to Forensic Pathology Service mortuaries in the WC over the two-year period.  An average decrease of 15.7% injury-related deaths in 2020 compared to 2019 was noted, as well as a 47.7% decrease in injury-related deaths during hard lockdown (April -May 2020) compared to the same period in 2019. In the injury-related deaths, 12,077 (75.4%) had blood specimens collected for BAC testing. In 5,078 (42.0%) of submitted cases, a positive BAC (≥0.01g/100 mL) was reported. No significant difference was observed in the mean positive BAC between 2019 and 2020, however in April and May 2020, the mean BACs observed (0.13 g/100 mL) was less than that in 2019 (0.18 g/100 mL). A high number of positive BACs in the 12-17-year age group (±23.4%) was observed.

CONCLUSION

There was a clear decrease in injury-related deaths in the WC during the COVID-19-related lockdown periods that coincided with the alcohol ban and restriction of movement and an increase following relaxation of restrictions on alcohol sales and movement. The data illustrated that mean BACs were similar between all periods of alcohol restriction compared to 2019, apart from hard lockdown in April-May, 2020.  This coincided with a smaller mortuary intake during the level 5 and 4 lockdown periods.   Keywords: Alcohol; blood alcohol concentration; COVID-19; injury; lockdown; South Africa; violent death; Western Cape   * Alcohol refers to ethanol.

Antimicrobial use in animals: a journey towards integrated surveillance

In 2015, the World Organisation for Animal Health (WOAH, founded as OIE) initiated the annual collection of data on antimicrobials intended for use in animals using a Microsoft Excel questionnaire. In 2022, WOAH initiated the migration to a customised interactive online system: ANIMUSE Global Database. This system enables national Veterinary Services not only to monitor and report data more easily and more accurately, but also to visualise, analyse and use data for surveillance purposes to their own benefit in the implementation of national action plans on antimicrobial resistance. This journey started seven years ago, with progressive improvements in the way data are collected, analysed and reported and continuous adaptations to overcome various challenges encountered (e.g. data confidentiality, training of civil servants, calculation of active ingredients, standardisation to enable fair comparisons and trend analyses, and data interoperability). Technical developments have been key in the success of this endeavour. However, it is important not to underestimate the importance of the human element: to listen to WOAH Members and their needs, and to exchange to solve issues, adapt tools, and gain and maintain trust. The journey is not over yet, and more developments are foreseen, such as to complement current data sources with data collected directly at the farm level; strengthen interoperability and integrated analysis with cross-sectoral databases; and facilitate institutionalisation of data collection and systematic use in monitoring, evaluation, lesson learning, reporting and, eventually, surveillance of antimicrobial use and antimicrobial resistance when implementing and updating national action plans. This paper describes how all these challenges were overcome and how future challenges will be addressed.

The Role of Alcohol and Drug Intoxication in Fire-Related Incidents in Africa: A Systematic Review

Fire-related burns contribute significantly to the global burden of burn injury and mortality. Alcohol and/or drug intoxication poses a risk to burn and fire-related injury, whether intentional or unintentional, but such evidence is scarce in the African context. This review aimed to fill the knowledge gap on health determinants of fire-related morbidity and mortality regionally by investigating the role of alcohol and drug intoxication in such events. Using key concepts, an extensive search was performed on 25 databases for relevant publications. Eligible articles were critically appraised using the appraisal tool for cross-sectional studies (AXIS tool), adapted to the review's objectives and outcomes. A total of 42 articles were included, of which less than half were solely investigating burn/fire-related events. Others indirectly mentioned burn injuries as part of larger health burdens such as injury, trauma, violence and other diseases. The measurement of alcohol and/or drug intoxication was inconsistent between studies with varying results. Alcohol and drug impairment in burn incidents in Africa requires evidence-based epidemiological research, and this review illustrated the limited scope of this topic in current literature. Routine toxicological results from post-mortem examinations were identified as important data sources and several research recommendations were provided.

Exploring the contribution of mechano-sensing to cardiomyopathy

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Medical Research Council (MR/V009540/1),

Wellcome Trust (201543/B/16/Z)

British Heart Foundation (FS/12/40/29712).

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac condition associated with diastolic dysfunction and sudden cardiac death. Disease genes for HCM are traditionally coding for proteins involved in force generation. More recently, it has emerged that variants in genes coding for proteins involved in biomechanical stress-signalling can also cause HCM.

One such protein is filamin C, with proposed mechano-sensing functions in the heart. Within the protein, the immunoglobulin-like domain 20 (Ig20) may play a crucial role in mediating binding to muscle specific ligands. While the mechano-sensing functions of filamin C have been investigated well in skeletal muscle, the underlying cardiac disease mechanisms are not completely understood.

Aim

This work attempts to provide insights into the role of filamin C in cardiac mechano-sensing and dissect disease pathways leading to HCM in the presence of the FLNC variants in Ig20.

Methods

Using mass spectrometry, we aimed to provide a detailed analysis of the proteome of mice carrying the filamin C variant, using ventricular tissue samples from 14wk old homozygous mice. Samples were subject to molecular biology technical and underwent subcellular fractionation (n = 6 per genotype) and were investigated by label-free mass spectrometry.

Results

Utilising whole genome sequencing, a heterozygous FLNC missense variant in Ig20 was identified in a three-generation family affected by HCM. Mice carrying this variant recapitulate molecular features of HCM in the homozygous setting. Three proteins (FLNC, MYH7, MYOT) were found to be upregulated in the myofilament-enriched fraction. Up-regulations of key proteins were found to relocalise towards load-baring sites.

Conclusion

Our data indicate that changes in filamin C and its binding partners expression and localisation are involved in the pathogenesis of HCM in this mouse model.

Crucial functions of alpha-actinin 2 in the embryonic heart

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Wellcome Trust; British Heart Foundation

Background/Introduction

Alpha-actinin is an integral protein of the Z-discs in heart and skeletal muscle cells, with important structural and signalling functions.  Missense variants in alpha-actinin can cause inherited conditions, e.g. myopathies and cardiomyopathies. The underlying disease mechanisms are still unknown.

Purpose

In order to study the disease mechanisms of an alpha-actinin missense variant, which is known to cause Hypertrophic Cardiomyopathy in human patients, a mouse model was generated.

Methods

Mice carrying the alpha-actinin missense variant were generated by CRISPR-Cas9 genome editing. The heterozygous adult mice carrying the alpha-actinin variant were characterised by echocardiography and quantitative PCR. Hearts of homozygous embryos were analysed at E15.5 by high-resolution episcopic microscopy (HREM).

Results

Mice carrying a single copy of the missense variant were viable and had normal appearance. Adult heterozygous mice showed no signs of cardiomyopathy on echocardiography. However, mature male mice displayed molecular signs of cardiomyopathy, such as induction of the fetal gene programme at transcript level.

The attempt to generate adult mice homozygous for the variant failed: 9 breeding pairs produced 18 litters with 83 weaned pups, but no homozygous offspring. Embryonic lethality was confirmed and E15.5 was the latest stage homozygous pups were reliably found to be viable. At this timepoint, genotype distribution was within the expected Mendelian ratios.

HREM of the hearts at this stage revealed increased right ventricular chamber size and decreased left atrial size, when compared to wildtype littermates. Membranous ventricular septal defects were observed in 3 out of 8 homozygous hearts. Further these embryos displayed aortic stenosis and dysplasic leaflets of the pulmonary valve.

Conclusions

Heterozygous adult mice only displayed sub-clinical signs of disease. In contrast, the missense variant is embryonic lethal in the homozygous setting and leads to a range of morphological abnormalities in E15.5 hearts. Future work will identify how altered functions of alpha-actinin cause these changes.

Sex-differences and utility of treadmill testing in identification and genotype prediction in LQTS: a sub-study of the national LQTS registry and Canadian Hearts in Rhythm registry

Background/Purpose

Long-QT (LQT) Syndrome is an inherited heart rhythm condition presenting with QT-prolongation and failure to shorten with exercise, leading to life-threatening cardiac events. The prevalent normal-to-borderline phenotype remains a challenge for diagnosis. A three-step algorithm was developed to predict genotype from phenotypic characteristics with exercise testing. Sex-specific cut offs for determining a prolonged corrected QT value are 470ms for males and 480ms for females, serving as step 1 in the algorithm. The purpose of this study is to validate the algorithm using a national cohort that is more representative of the general LQT population, with a milder phenotype and more frequent ambiguity in phenotype.

Methods

A review of cases in the Canadian National Long-QT Registry, housed in the HiRO Registry was undertaken. Eligible cases from September 2014 to May 2020 were included. Gene-positive patients included 93 probands and 122 first-degree relatives (FDR) with a likely-pathogenic or pathogenic mutation according to ACMG criteria, limited to LQT1/2 subtypes, with 164 and 51 patients, respectively. Controls were composed of 39 gene-negative FDRs. Continuous variables were compared by the Mann-Whitney U test for 2-group comparisons, and Kruskal-Wallis test for multiple group comparisons. The predictive value of exercise ECG characteristics were analysed using ROC analysis and optimal cut-off values for exercise ECG characteristics (supine, standing, peak exercise, 1 and 4-minutes into recovery) were determined for males and females, using a sensitivity of 0.80 for carrier status and 0.75 for subtype.

Results

The 4-minute recovery QTc had the best predictive value for males, with an AUC of 0.86, and a cut-off point of 442ms given a sensitivity of 0.81 and specificity of 0.86. The 4-minute recovery QTc yielded an AUC of 0.79 for females, with a cut-off of 452ms given a sensitivity of 0.81 and specificity of 0.71. The 1-minute recovery QTc had the best predictive value for females, with an AUC of 0.92 and a cut-off point of 424ms given a sensitivity of 0.82 and specificity of 0.94. In prediction of LQT1, the 1-minute recovery QTc yielded the highest AUC for both males and females, at 0.68 and 0.80, respectively. Males had a cut off of 428ms with a sensitivity of 0.75 and specificity of 0.47, while females had a cut off of 451ms given a sensitivity of 0.76 and specificity of 0.75.

Conclusion

The current study demonstrates that exercise testing is a valid approach to diagnosing LQTS, with a differential optimal best measurement in males vs. females. Test performance measured by AUC was generally better at all time points in females compared to males. The algorithm is a reliable and simple method for the identification and prediction of genotype for probands and FDR carriers. The algorithm should be sex-stratified at the second step, with the 4-minute recovery QTc used for males and the 1-minute recovery QTc for females.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Canadian Institute of Health Research

619 Is the Subdivision of Thy3 Nodules Needed? An Audit Reviewing the Management of Thy3 Nodules, and the Associated Malignancy Rates

Introduction

Following the 2014 update to the BAETS thyroid nodule cytology guidance, the management of Thy3 lesions was modified by subdivision into Thy3a and Thy3f categories. Both lesions remain indeterminate but are proposed to have differing risks of malignancy when counselling patents: these risks have been called into question by subsequent data.

Aim

This Audit aimed to review the management of Thy3 (Thy3a and Thy3f) cytological diagnoses, within an NHS Trust, and compare this to the BAET Guidance 2014. Further, malignancy rates for Thy3a and Thy3f cytology were made over the calculated over the time period.

Method

A retrospective Audit looking at 118 patients with a Thy3 cytology identified between 2014 and 2019. Data separated into data pre-2015 and 2015 onwards.

Results

In 2014, 29% of Thy3a nodules were managed in line with 2014 BAETS guidance. This improved to 34% from 2015. Meanwhile, Thy3f diagnoses were managed mostly in favour of the BAETS guidelines – 83% in 2014 and 92% 2015 onwards. The malignancy rates found, amongst all 118 patients, were 17.2% and 14.8% for Thy3f and Thy3a nodules respectively.

Conclusions

At this institution, Thy3 cytological diagnoses, regardless of classification into Thy3a or Thy3f, were largely treated in the same way (by a diagnostic hemi-thyroidectomy). The management of the nodules may reflect a variety of factors, including how comfortable patients and surgeons are when handling uncertainty. With malignancy rates for both Thy3a and Thy3f nodules being much the same, it is not surprising that they are managed in a similar way.

1671 The Effect Of COVID-19 On the Management and Outcome of Neck of Femur Fractures in A District General Hospital - A Comparative Study

Aim

We wanted to see how the virus has impacted the management and outcome of our neck of femur fracture patients during Spring 2020.

Method

We performed a retrospective study of all neck of femur fracture patients presenting to our hospital from 23rd March 2020 (start of official lockdown in UK) until the end of May 2020 and compared them to patients presenting in the same time period in 2019. We recorded patient demographics, COVID-19 swab results, time to surgery, length of stay, transfers between wards, and 30-day mortality rates.

Results

We identified 75 patients in 2020 compared to 88 in 2019. Average length of stay was 11.4 days compared to 14.3 a year earlier. Mean time to surgery was 32.3 hours compared to 31.6 in 2019. The 30-day mortality increased significantly from 5.7% (5/88) in 2019 to 16% (12/75) in 2020 (p < 0.05) From 73 patients tested for COVID-19, 3 had a positive swab. Of these, 2 died. During their admission, 14 patients were transferred to 3 or more wards; in this group, 30-day mortality was 42.9% (6/14).

Conclusions

There has been a significant increase in 30-day mortality during COVID-19. Despite maintaining our time to surgery and reducing overall length of stay, we saw an increase in mortality, associated with multiple ward transfers rather than a high number of COVID-19 positive swab cases. Changes in pathways and wards configurations led to some patients requiring multiple transfers. This can cause difficulties in coordinated, multidisciplinary care for patients with NOF Fractures.

1085 Equestrian Related Pelvic and Acetabular Fractures – Experience from a Major Trauma Centre in England

Introduction

Equestrianism is enjoyed by three million people in the UK; however, there is a lack of literature on pelvic and acetabular (P&A) injuries incurred through the sport. We aim to describe P&A injuries sustained in equestrian accidents, discuss management, and establish their outcomes.

Method

Data was extracted from a prospectively collected database of referrals to the P&A Service of a Major Trauma Centre (MTC) from 01/01/2016 to 31/12/2020 and cross-referenced with medical records.

Results

60 of the 1,218 P&A referrals were secondary to horse-riding accidents. Mean age 45 (SD 16.59); 46 female; 33 managed non-operatively and 27 managed operatively at the MTC. There was sufficient information for 59 cases to be classified; 46 of the injuries were pelvic fractures (10 anterior-posterior compression; 29 lateral compression; 4 sacral and 3 pubic rami fractures) and 13 were acetabular (2 anterior column; 1 anterior wall; 2 associated both columns; 1 posterior column and posterior wall; 1 posterior wall; 2 T-shaped and 4 transverse fractures). The operative group were managed by examination under anaesthesia (n = 3), open reduction internal fixation (n = 22) or percutaneous fixation (n = 2). Mean hospitalisation was 9.2 days (SD 5.44). 81% were non-weight-bearing post-operatively and mean time to independent mobilisation was 12.6 weeks (SD 7.09). Return-to-riding information was available for 8 patients with a mean of 29.5 weeks (SD 11.55).

Conclusions

Equestrianism can result in significant P&A injuries. Patients should be counselled that they may have a long recovery, a protracted return-to-riding time and some may never return to the sport.

1514 Higher Mortality in Pelvic Acetabular Fractures Is Associated with Lower Body Mass Index

Aim

Fractures of the pelvis and acetabulum can be life-threatening or life changing injuries. Multiple factors can contribute to outcome including age, frailty, and baseline nutritional status. The aim of this study was to identify if low BMI (<18.5) was a predictor of outcome for patients with such injuries in terms of morbidity and mortality.

Method

We retrospectively analysed 1033 patients with pelvic or acetabular fractures referred to a single level 1 major trauma centre over a 4.5-year period (August 2015 - January 2020). Of these patients, 569 were admitted to the centre and included in our analysis. Data was collected on demographics, injury pattern, operative intervention, and complications. Comparison was made between patients that were underweight (BMI<18.5) and patients that were not, for in-hospital and post discharge complications including pulmonary embolus (PE), deep venous thrombosis (DVT), ileus, infection, loss of reduction and mortality at 6 months.

Results

Underweight patients had a statistically significant increase in mortality both in-hospital (p = 0.019) and at 6 months post injury (p = 0.039) when compared to other BMI groups. No statistical significance was found between these BMI groups comparing morbidity: DVT (p = 0.712), PE (p = 0.736) nor ileus (p = 0.149). Covariate analysis showed that a low BMI was associated with 3 times increased in-hospital mortality after correction for age and energy of injury (adjusted OR 3.028, 95% CI 1.059-8.659).

Conclusions

This study suggests increased mortality in patients with pelvic or acetabular fractures who are underweight. Surgeons should consider these findings in initiating appropriate peri-operative optimisation for these patients.

Pus Samples in Complicated Appendicitis: An Important Investigation or a Waste of Resources: A Prospective Cohort Study

BACKGROUND AND AIMS:

Appendicitis is a common presentation to hospital with appendectomy being the treatment of choice. Pre-operative administration of broad-spectrum antibiotics is common, but obtaining intra-abdominal pus samples is not. After an initial 6-month retrospective audit and departmental teaching on the importance of intra-peritoneal pus sampling, we aimed to determine whether intra-operative pus samples changed antibiotic management.

MATERIALS AND METHODS:

Following the initial audit cycle, a 6-month prospective cohort study was conducted. Clinical data were collected on a predetermined proforma to assess the effectiveness of the intervention and antibiotic prescribing practice. The data collected during the whole 1-year period was analyzed.

RESULTS:

During the 1-year period, 440 patients were identified as undergoing a laparoscopic procedure. After exclusion, 261 patients were identified as undergoing laparoscopic appendectomies, of which 141 (54%) were classified as complicated laparoscopic appendectomies. A total of 35 out of 141 (25%) pus samples were sent of which 24 (17%) resulted in positive cultures, with only nine of these positive cultures reported prior to the patient being discharged. No patient had their antibiotic regimen changed as a result of the culture results. There were three cases of cultures resistant to local antibiotics, but without significant clinical outcome. One of these patients developed a post-operative complication, but the antibiotic regimen was changed to broad spectrum rather than a specific antibiotic based on culture sensitivity. Of the 141 patients with complicated laparoscopic appendectomies, five (3.5%) developed post-operative complications: one readmission requiring a laparoscopic washout for pelvic collection, three (2%) cases of pelvic collections managed conservatively, and one case of prolonged paralytic ileus managed non-operatively.

CONCLUSION:

Overall, none of the patients with positive cultures had a change in prescribed antibiotics based on culture results. Hence, the routine practice of intra-peritoneal pus sampling following complicated appendicitis remains of little clinical value.

P90 A systematic review of spinal cord serum and cerebrospinal fluid biomarkers for use in degenerative cervical myelopathy

Objectives

Whilst radiological evidence of compression is the hallmark of degenerative cervical myelopathy [DCM], it is unable to stage or prognosticate. Moreover, asymptomatic spinal cord compression is common and therefore new methods of assessing spinal cord function are required. We aimed to: 1) Evaluate the evidence-base for serum and CSF biomarkers of spinal cord damage in diagnosis, prognosis or predicting response to treatment in DCM 2) Identify serum and CSF biomarkers of spinal cord damage studied in other conditions, which may have relevance to DCM.

Design

Scoping review.

Subjects

Human only.

Methods

A search of MEDLINE and EMBASE was performed. Studies involving DCM patients or biomarkers relevant to spinal cord pathobiology were included.

Results

852 results were screened, of which 83 were included. 9 studies explored 12 biomarkers in DCM. NFH (n=3), S100b and NSE (n=2) received most study. 74 studies explored a further 118 biomarkers in other conditions; S100b (n=13), NFH (n=11) and GFAP (n=10) received most study. Overall, 72 studies used targeted approaches, in which candidate biomarkers were chosen in advance. 11 used unbiased approaches, in which high throughput analyses identified candidate biomarkers during the study.

Conclusions

The evidence-base for use of biomarkers in DCM is limited. Whilst targeted approaches have identified a number of candidate spinal cord markers, few have shown clinical utility. There is a shift towards investigating panels of multiple markers and unbiased, high-throughput approaches.