The Blunt Liver and Spleen Trauma (BLAST) audit: national survey and prospective audit of children with blunt liver and spleen trauma in major trauma centres

PURPOSE

To compare the reported and observed management of UK children with blunt liver or spleen injury (BLSI) to the American Pediatric Surgical Association (APSA) 2019 BLSI guidance.

METHODS

UK Paediatric Major Trauma Centres (pMTCs) undertook 1 year of prospective data collection on children admitted to or discussed with those centres with BLSI and an online questionnaire was distributed to all consultants who care for children with BLSI in those centres.

RESULTS

All 21/21 (100%) pMTCs participated; 131 patients were included and 100/152 (65%) consultants responded to the survey. ICU care was reported and observed to be primarily determined using haemodynamic status or concomitant injuries rather than injury grade, in accordance with APSA guidance. Bed rest was reported to be determined by grade of injury by 63% of survey respondents and observed in a similar proportion of patients. Contrary to APSA guidance, follow-up radiological assessment of the injured spleen or liver was undertaken in 44% of patients before discharge and 32% after discharge, the majority of whom were asymptomatic.

CONCLUSIONS

UK management of BLSI differs from many aspects of APSA guidance. A shift towards using clinical features to determine ICU admission and readiness for discharge is demonstrated, in line with a strong evidence base. However, routine bed rest and re-imaging after BLSI is common, contrary to APSA guidance. This disparity may exist due to concern that evidence around the incidence, presentation and natural history of complications after conservatively managed BLSI, particularly bleeding from pseudoaneurysms, is weak.

Implementation of a novel team-based model of care using expert intensive care unit physiotherapists to supplement critical care surge demand

Within Victoria, Australia, the emergence of the Delta variant resulted in a significant and rapid increase in case numbers and high demand for intensive care beds statewide. While prior pandemic planning had been undertaken at a state level, the Delta variant necessitated a need for further rapid expansion of intensive care unit (ICU) beds. Our hospital subsequently implemented a Department of Health-designed team-based model of care to support this rapid ICU expansion-where tasks were allocated according to skill and not discipline. Here we report our local experiences as critical care physiotherapists participating in this novel model of care for physiotherapists to support the functioning of the ICU under peak pandemic surge conditions. Our core skill set as ICU-trained physiotherapists, including depth knowledge of the assessment and treatment of critical care patients, and ICU functioning, enabled us to play a contributing role in team-based care. We discuss our reflections and lessons learnt including future directions for clinicians, educators, managers, policymakers, and researchers to refine implementation of this novel model of care and how these lessons could be leveraged in future scenarios where healthcare systems might be significantly strained by future pandemics.

Clinical Reasoning: A 59-Year-Old Man With Thymoma and Constitutional Symptoms, Seizures, and Multifocal CNS Lesions

A 59-year-old man first presented for an episode of left arm numbness. During workup, a thymoma was incidentally discovered and resected. The symptoms in his left arm were attributed to a cardiac pathology. One month later, he began to experience fatigue, weight loss, and anorexia, followed by one generalized tonic-clonic seizure. Workup including toxic and metabolic screening and MRI of the brain were unremarkable. He was started on an antiseizure medication and did well for 2 years, when his symptoms recurred. Repeat MRI of the brain showed multiple cortical T2-weighted fluid-attenuated inversion recovery (T2/FLAIR) hyperintense lesions without enhancement or diffusion restriction. Further workup included spinal MRI, CT of the chest/abdomen/pelvis, CSF studies, and autoimmune/paraneoplastic panels in CSF and serum, all of which were unremarkable. Serum testing was positive for striational antibodies, acetylcholine receptor (AChR)-binding antibodies, and AChR-modulating antibodies. He received high-dose steroids and plasma exchange with resolution of his symptoms and has since been stable on mycophenolate mofetil. This presentation highlights the rare association between thymoma and encephalitis. Prompt identification and treatment is critical. This article discusses the diagnostic approach to this rare presentation including essential features of the clinical presentation, appropriate workup, pertinent differential diagnoses, and key points for the treatment of these patients.

CSIG-20. PROTEOGENOMICS PROFILING REVEALS ENRICHED PROTEIN TRANSLATION REGULATORS AS NEW THERAPEUTIC TARGETS IN DIPG

Diffuse intrinsic pontine glioma (DIPG) is a devastating brain tumor arising in the brainstems of children. Current therapies are ineffective resulting in a median survival rate of less than one year and it is the leading cause of brain tumor-related death in children. A novel mutation in histone H3 protein (H3K27M) was recently identified as a genetic initiation event and affects global K27 trimethylation on histone H3 proteins and DNA methylation. The epigenetic changes caused by H3K27M mutation suggest the existence of an H3K27M-specific transcriptome and proteome. We investigated DIPG tissues at the multi-omics level including total proteome, phosphoproteome, methylproteome and metabolome by mass spectrometry. A total of 30 patient tumours were profiled to identify differentially expressed proteins, differentially phosphorylated proteins, and differentially methylated proteins in tumour tissues compared to normal brains. We identified 2995 proteins that are differentially regulated, suggesting changes in key oncogenic pathways including negative regulation of apoptosis, translation, and metabolic pathways such as methionine salvage and TCA cycle in DIPG. The deregulation of these metabolic pathways due to the differentially expressed proteins in DIPG cells was confirmed by metabolomics studies. Protein phosphorylation and protein methylation profiling of DIPG implicated that translation-related proteins were the most highly modified (post-translationally) proteins in DIPG tissues. Furthermore, protein translation measured by CyTOF showed higher translation rates in DIPG and immortalized astrocytes carrying H3K27M than their WT counterparts. We investigated the functional consequence of knockdown of the highest methylated translation regulator EEF1A1 and its methyltransferase METTL13. ShRNA knockdown of both, EEF1A and METTL13 in DIPG cells significantly reduced the cell growth. Multi-omics analysis of DIPG highlighted regulation of protein translation as a potential therapeutic target.

Brachial Plexus Tolerance to Single-Session SAbR in a Pig Model

PURPOSE

The single-session dose tolerance of the spinal nerves has been observed to be similar to that of the spinal cord in pigs, counter to the perception that peripheral nerves are more tolerant to radiation. This pilot study aims to obtain a first impression of the single-session dose-response of the brachial plexus using pigs as a model.

METHODS AND MATERIALS

Ten Yucatan minipigs underwent computed tomography and magnetic resonance imaging for treatment planning, followed by single-session stereotactic ablative radiotherapy. A 2.5-cm length of the left-sided brachial plexus cords was irradiated. Pigs were distributed in 3 groups with prescription doses of 16 (n = 3), 19 (n = 4), and 22 Gy (n = 3). Neurologic status was assessed by observation for changes in gait and electrodiagnostic examination. Histopathologic examination was performed with light microscopy of paraffin-embedded sections stained with Luxol fast blue/periodic acid-Schiff and Masson's trichrome.

RESULTS

Seven of the 10 pigs developed motor deficit to the front limb of the irradiated side, with a latency from 5 to 8 weeks after irradiation. Probit analysis of the maximum nerve dose yields an estimated ED₅₀ of 19.3 Gy for neurologic deficit, but the number of animals was insufficient to estimate 95% confidence intervals. No motor deficits were observed at a maximum dose of 17.6 Gy for any pig. Nerve conduction studies showed an absence of sensory response in all responders and absent or low motor response in most of the responders (71%). All symptomatic pigs showed histologic lesions to the left-sided plexus consistent with radiation-induced neuropathy.

CONCLUSIONS

The single-session ED₅₀ for symptomatic plexopathy in Yucatan minipigs after irradiation of a 2.5-cm length of the brachial plexus cords was determined to be 19.3 Gy. The dose-response curve overlaps that of the spinal nerves and the spinal cord in the same animal model. The relationship between the brachial plexus tolerance in pigs and humans is unknown, and caution is warranted when extrapolating for clinical use.

Ganglionic Acetylcholine Receptor Antibodies in Postural Tachycardia Syndrome

Objective

Postural tachycardia syndrome (POTS), the most common form of dysautonomia, may be associated with autoimmunity in some cases. Autoantibodies against the ganglionic acetylcholine receptor (gAChR) have been reported in a minority of patients with POTS, but the prevalence and clinical relevance is unclear.

Methods

Clinical information and serum samples were systematically collected from participants with POTS and healthy control volunteers (n = 294). The level of positive gAChR antibodies was classified as very low (0.02-0.05 nmol/L), low (0.05-0.2 nmol/L), and high (>0.2 nmol/L).

Results

Fifteen of 217 patients with POTS (7%) had gAChR antibodies (8 very low and 7 low). Six of the 77 healthy controls (8%) were positive (3 very low and 3 low). There were no clinical differences between seropositive and seronegative patients with POTS.

Conclusions

Prevalence of gAChR antibody did not differ between POTS and healthy controls, and none had high antibody levels. Patients with POTS were not clinically different based on seropositivity. Low levels of gAChR antibodies are not clinically important in POTS.

Pregnant women's use of e-cigarettes in the UK: a cross-sectional survey

OBJECTIVE

To estimate prevalence of vaping in pregnancy. Compare characteristics and attitudes between exclusive smokers and vapers, and between exclusive vapers and dual users (smoke and vape).

DESIGN

Cross-sectional survey.

SETTING

Hospitals across England and Scotland.

POPULATION

Pregnant women attending antenatal clinics in 2017.

METHODS

Women at 8-24 weeks' gestation completed screening questions about their smoking and vaping. Current or recent ex-smokers and/or vapers completed a full detailed survey about vaping and smoking.

MAIN OUTCOME MEASURES

The prevalence of vaping, characteristics and attitudes of women who vape and/or smoke.

RESULTS

Of 3360 pregnant women who completed screening questions, 515 (15.3%, 95% CI 14.1-16.6) were exclusive smokers, 44 (1.3%, 95% CI 1.0-1.8) exclusive vapers and 118 (3.5%, 95% CI 2.9-4.2) dual users. In total, 867 (25.8%) women completed the full survey; compared with smokers (n = 434), vapers (n = 140) were more likely to hold higher educational qualifications (odds ratio [OR) 1.51, 95% CI 1.01-2.25). Compared with exclusive vapers (n = 33), dual users (n = 107) were younger (OR 0.91 95% CI 0.85-0.98) and less likely to hold high qualifications (OR 0.43, 95% CI 0.20-0.96). Compared with smokers, dual users were more likely to be planning to quit smoking (OR 2.27, 95% CI 1.24-4.18). Compared with smokers, vapers were more likely to think vaping was safer than smoking (78.6% versus 36.4%).

CONCLUSIONS

One in 20 pregnant women report vaping, and most also smoke. Dual users are more motivated towards stopping smoking than smokers. Where women have tried but cannot stop smoking, clinicians could encourage them to consider vaping for smoking cessation.

TWEETABLE EXTRACT

One in 20 women report vaping during pregnancy but of those that do vape, most also smoke, despite having intentions to quit.

Novel free-circulating and extracellular vesicle-derived miRNAs dysregulated in Duchenne muscular dystrophy

Aim: To perform cross-sectional and longitudinal miRNA profiling in plasma from Duchenne muscular dystrophy (DMD) subjects and find non-invasive biomarkers in DMD. Subjects/materials & methods: Plasma was collected from 14 age and sex matched controls and 46 DMD subjects. Free-circulating and extracellular vesicle (EV)-derived miRNA expression was measured by RT-qPCR. Results: Free-circulating and EVs derived miR-29c-3p and miR-133a-3p are dysregulated in DMD subjects. Free-circulating and EV-derived miR-29c-3p are reduced in DMD subjects undergoing daily corticosteroid treatment. Free-circulating miR-1-3p and miR-122-5p are longitudinally upregulated in ambulant DMD subjects. Conclusion: We detected novel free-circulating and EV-derived dysregulated miRNAs in plasma from DMD subjects and characterized the longitudinal profile of free-circulating miRNA on plasma from DMD subjects.

Usefulness of Blood Pressure Variability Indices Derived From 24-Hour Ambulatory Blood Pressure Monitoring in Detecting Autonomic Failure

Background Increased blood pressure ( BP ) variability and nondipping status seen on 24-hour ambulatory BP monitoring are often observed in autonomic failure ( ATF ). Methods and Results We assessed BP variability and nocturnal BP dipping in 273 patients undergoing ambulatory BP monitoring at Southwestern Medical Center between 2010 and 2017. SD , average real variability, and variation independent of mean were calculated from ambulatory BP monitoring. Patients were divided into a discovery cohort (n=201) and a validation cohort (n=72). ATF was confirmed by formal autonomic function test. In the discovery cohort, 24-hour and nighttime average real variability, SD , and variation independent of mean did not differ significantly between ATF (n=25) and controls (n=176, all P>0.05). However, daytime SD, daytime coefficient of variation, and daytime variation independent of mean of systolic BP ( SBP ) were all significantly higher in patients with ATF than in controls in both discovery and validation cohorts. Nocturnal BP dipping was more blunted in ATF patients than controls in both cohorts (both P<0.01). Using the threshold of 16 mm Hg, daytime SD SBP yielded a sensitivity of 77% and specificity of 82% in detecting ATF in the validation cohort, whereas nondipping status had a sensitivity of 80% and specificity of 44%. The area under the receiver operator characteristic of daytime SD SBP was greater than the area under the receiver operator characteristic of nocturnal SBP dipping (0.79 [0.66-0.91] versus 0.73 [0.58-0.87], respectively). Conclusions Daytime SD of SBP is a better screening tool than nondipping status in detecting autonomic dysfunction.

Existence of a Dose-Length Effect in Spinal Nerves Receiving Single-Session Stereotactic Ablative Radiation Therapy

PURPOSE

The spinal nerves have been observed to have a similar single-session dose tolerance to that of the spinal cord in pigs. Small-animal studies have shown that spinal cord dose tolerance depends on the length irradiated. This work aims to determine whether a dose-length effect exists for spinal nerves.

METHODS AND MATERIALS

Twenty-seven Yucatan minipigs underwent computed tomography and magnetic resonance imaging for treatment planning, followed by single-session stereotactic ablative radiation therapy. A 0.5 cm length of the left-sided C6, C7, and C8 spinal nerves was targeted. The pigs were distributed into 6 groups with prescription doses of 16 Gy (n = 5), 18 Gy (n = 5), 20 Gy (n = 5), 22 Gy (n = 5), 24 Gy (n = 5), or 36 Gy (n = 2) and corresponding maximum doses of 16.7, 19.1, 21.3, 23.1, 25.5, and 38.6 Gy, respectively. Neurologic status was assessed with a serial electrodiagnostic examination and daily observation of gait for approximately 52 weeks. A histopathologic examination of paraffin-embedded sections with Luxol fast blue/periodic acid-Schiff's staining was also performed.

RESULTS

Marked gait change was observed in 8 of 27 irradiated pigs. The latency for responding pigs was 11 to 16 weeks after irradiation. The affected animals presented with a limp in the left front limb, and 62.5% of these pigs had electrodiagnostic evidence of denervation in the C6 and C7 innervated muscles. A probit analysis showed the dose associated with a 50% incidence of gait change is 23.9 Gy (95% confidence interval, 22.5-25.8 Gy), which is 20% higher than that reported in a companion study where a 1.5 cm length was irradiated. All symptomatic pigs had demyelination and fibrosis in the irradiated nerves, but the contralateral nerves and spinal cord were normal.

CONCLUSIONS

A dose-length effect was observed for single-session irradiation of the spinal nerves in a Yucatan minipig model.

Disruption of embryonic ROCK signaling reproduces the sarcomeric phenotype of hypertrophic cardiomyopathy

Sarcomeric disarray is a hallmark of gene mutations in patients with hypertrophic cardiomyopathy (HCM). However, it is unknown when detrimental sarcomeric changes first occur and whether they originate in the developing embryonic heart. Furthermore, Rho kinase (ROCK) is a serine/threonine protein kinase that is critical for regulating the function of several sarcomeric proteins, and therefore, our aim was to determine whether disruption of ROCK signaling during the earliest stages of heart development would disrupt the integrity of sarcomeres, altering heart development and function. Using a mouse model in which the function of ROCK is specifically disrupted in embryonic cardiomyocytes, we demonstrate a progressive cardiomyopathy that first appeared as sarcomeric disarray during cardiogenesis. This led to abnormalities in the structure of the embryonic ventricular wall and compensatory cardiomyocyte hypertrophy during fetal development. This sarcomeric disruption and hypertrophy persisted throughout adult life, triggering left ventricular concentric hypertrophy with systolic dysfunction, and reactivation of fetal gene expression and cardiac fibrosis, all typical features of HCM. Taken together, our findings establish a mechanism for the developmental origin of the sarcomeric phenotype of HCM and suggest that variants in the ROCK genes or disruption of ROCK signaling could, in part, contribute to its pathogenesis.

Disruption of ROCK activity in embryonic cardiomyocytes revealed a developmental origin for hypertrophic cardiomyopathy.

Shifting the paradigm in outreach to under-represented groups

This article was migrated. The article was marked as recommended. The Community of Support (COS) is a longitudinal and collaborative initiative that enables students who are Indigenous, Black, Filipino, economically disadvantaged, or who self-identify with having a disability to join and receive support at any stage of their medical school journey. The goal of COS is to increase diversity in the fields of research and medicine, as a diverse physician taskforce is essential to meeting the needs of Canada's patient population. Our program supports students at various points in their academic careers, beginning from first year of undergrad to end of PhD and into the workforce. We offer a variety of support systems that aim to address gaps and empower students. Our three-pronged approach provides COS members with support at the levels of i) admissions information, ii) mentorship and experiential opportunities, and iii) application support (including MCAT prep). Over the past 3 years, we have grown to include over 1,100 participants at various stages of their medical school journeys, from first year undergraduate students to university graduates from institution across Canada. As a result, in just three years, we have supported over 80 students with successful admissions to medical school, and alumni from CoS are now represented in 11/15 Canada's medical schools, with a growing number of US schools, such as Yale University, George Washington, Michigan State and Wayne State.

Skeletal Muscle Channelopathies

Skeletal muscle channelopathies are rare heterogeneous diseases with marked genotypic and phenotypic variability. These disorders cause lifetime disability and impact quality of life. Despite advances in understanding of the molecular pathology of these disorders, the diverse phenotypic manifestations remain a challenge in diagnosis, therapeutic, genetic counseling, and research planning. Electrodiagnostic testing is useful in directing the diagnosis, but has several limitations: patient discomfort, time consuming, and significant overlap of findings in muscle channelopathies. Although genetic testing is the gold standard in making a definitive diagnosis, a mutation might not be identified in many patients with a well-supported clinical diagnosis of periodic paralysis. In the recent past, there have been landmark clinical trials in non-dystrophic myotonia and periodic paralysis which are encouraging as they demonstrate the ability of robust clinical research consortia to conduct well-controlled trials of rare diseases.

Limb girdle muscular dystrophy due to mutations in POMT2

BACKGROUND

Mutations in the gene coding for protein O-mannosyl-transferase 2 (POMT2) are known to cause severe congenital muscular dystrophy, and recently, mutations in POMT2 have also been linked to a milder limb-girdle muscular dystrophy (LGMD) phenotype, named LGMD type 2N (LGMD2N). Only four cases have been reported so far.ClinicalTrials.gov ID: NCT02759302 METHODS: We report 12 new cases of LGMD2N, aged 18-63 years. Muscle involvement was assessed by MRI, muscle strength testing and muscle biopsy analysis. Other clinical features were also recorded.

RESULTS

Presenting symptoms were difficulties in walking, pain during exercise, delayed motor milestones and learning disabilities at school. All had some degree of cognitive impairment. Brain MRIs were abnormal in 3 of 10 patients, showing ventricular enlargement in one, periventricular hyperintensities in another and frontal atrophy of the left hemisphere in a third patient. Most affected muscle groups were hip and knee flexors and extensors on strength testing. On MRI, most affected muscles were hamstrings followed by paraspinal and gluteal muscles. The 12 patients in our cohort carried 11 alleles with known mutations, whereas 11 novel mutations accounted for the remaining 13 alleles.

CONCLUSION

We describe the first cohort of patients with LGMD2N and show that unlike other LGMD types, all patients had cognitive impairment. Primary muscle involvement was found in hamstring, paraspinal and gluteal muscles on MRI, which correlated well with reduced muscle strength in hip and knee flexors and extensors. The study expands the mutational spectrum for LGMD2N, with the description of 11 novel POMT2 mutations in the association with LGMD2N.

CLINICAL TRIAL REGISTRATION

NCT02759302.

Downregulation of miRNA-29, -23 and -21 in urine of Duchenne muscular dystrophy patients

AIM

To study the signature of 87 urinary miRNAs in Duchenne muscular dystrophy (DMD) patients, select the most dysregulated and determine statistically significant differences in their expression between controls, ambulant (A) and nonambulant (NA) DMD patients, and patients on different corticosteroid regimens. Patients/materials & methods: Urine was collected from control (n = 20), A (n = 31) and NA (n = 23) DMD patients. miRNA expression was measured by reverse transcription-quantitative PCR.

RESULTS

miR-29c-3p was significantly downregulated in A DMD patients while miR-23b-3p and miR-21-5p were significantly downregulated in NA DMD patients compared with age-matched controls.

CONCLUSION

miR-29c-3p, miR-23b-3p and miR-21-5p are promising novel noninvasive biomarkers for DMD, and miR-29c-3p levels are differentially affected by different steroid regimens, supporting the antifibrotic effect of steroid therapy.

The utility of bone marrow sampling in the diagnosis and staging of lymphoma in South Africa

INTRODUCTION

The bone marrow biopsy (BMB) is a diagnostic and staging tool in lymphoma that remains practically useful and relevant in resource-constrained settings, despite restricted applications in international staging guidelines, which favour less invasive nuclear medicine techniques.

METHODS

Retrospective laboratory data review of BMBs in adult lymphoma patients from 2005 to 2010 to determine subtypes, rates of bone marrow involvement (BMI), human immunodeficiency virus (HIV) seroprevalence and CD4 counts, trephine length and additional findings.

RESULTS

A total of 1215 BMBs reported in lymphoma included 759 newly diagnosed patients, with BMI in 43.6% of non-Hodgkin lymphoma (NHL) overall, 28.9% of high-grade B subtypes and 35.7% of Hodgkin lymphoma (HL). HIV seroprevalence was 38.8%, 53.0% and 33.9% in the 3 respective groups. There was a statistical association between BMI and HIV seropositivity in Burkitt lymphoma and HL, and BMI and CD4 count in HIV-related HL. Over 10% (n = 79) of new lymphoma cases were diagnosed by BMB with ancillary tests. Occasional histological discordance and transformation were reported in NHL. Focal/unilateral BMI was uncommon. Bilateral BMB and biopsy length exceeding 26 mm did not improve BMI detection.

CONCLUSION

In the South African public sector, high HIV prevalence leads to a different lymphoma pathology profile from the developed world. High BMI rates are encountered. Here, and in similar resource-constrained settings, international lymphoma staging guidelines can be logistically challenging and unaffordable. BMB remains useful in the staging and diagnosis of lymphoma. Unilateral sampling with a processed trephine length of at least 26 mm is recommended.

Ratite cancellous xenograft: effects on avian fracture healing

A segmental radial defect model was used to radiographically and histologically evaluate response to ratite cancellous xenograft in pigeons. The control group showed little evidence of callus production with all fractures proceeding to nonunion. Lymphocytic response to xenograft peaked at four weeks and diminished thereafter. Fractures treated with cancellous xenograft had significant increases in new bone production.

Identification of GAA variants through whole exome sequencing targeted to a cohort of 606 patients with unexplained limb-girdle muscle weakness

Background

Late-onset Pompe disease is a rare genetic neuromuscular disorder caused by a primary deficiency of α-glucosidase and the associated accumulation of glycogen in lysosomal vacuoles. The deficiency of α-glucosidase can often be detected using an inexpensive and readily accessible dried blood spot test when Pompe disease is suspected. Like several neuromuscular disorders, Pompe disease typically presents with progressive weakness of limb-girdle muscles and respiratory insufficiency. Due to the phenotypic heterogeneity of these disorders, however, it is often difficult for clinicians to reach a diagnosis for patients with Pompe disease. Six hundred and six patients from a European population were recruited onto our study. Inclusion criteria stipulated that index cases must present with limb-girdle weakness or elevated serum creatine kinase activity. Whole exome sequencing with at least 250 ng DNA was completed using an Illumina exome capture and a 38 Mb baited target. A panel of 169 candidate genes for limb-girdle weakness was analysed for disease-causing variants.

Results

A total of 35 variants within GAA were detected. Ten distinct variants in eight unrelated index cases (and four siblings not sequenced in our study) were considered disease-causing, with the patients presenting with heterogeneous phenotypes. The eight unrelated individuals were compound heterozygotes for two variants. Six patients carried the intronic splice site c.-13 T > G transversion and two of the six patients also carried the exonic p.Glu176ArgfsTer45 frameshift. Four of the ten variants were novel in their association with Pompe disease.

Conclusions

Here, we highlight the advantage of using whole exome sequencing as a tool for detecting, diagnosing and treating patients with rare, clinically variable genetic disorders.

Impaired glycogen breakdown and synthesis in phosphoglucomutase 1 deficiency

OBJECTIVE

We investigated metabolism and physiological responses to exercise in an 18-year-old woman with multiple congenital abnormalities and exertional muscle fatigue, tightness, and rhabdomyolysis.

METHODS

We studied biochemistry in muscle and fibroblasts, performed mutation analysis, assessed physiological responses to forearm and cycle-ergometer exercise combined with stable-isotope techniques and indirect calorimetry, and evaluated the effect of IV glucose infusion and oral sucrose ingestion on the exercise response.

RESULTS

Phosphoglucomutase type 1 (PGM1) activity in muscle and fibroblasts was severely deficient and PGM1 in muscle was undetectable by Western blot. The patient was compound heterozygous for missense (R422W) and nonsense (Q530X) mutations in PGM1. Forearm exercise elicited no increase in lactate, but an exaggerated increase in ammonia, and provoked a forearm contracture. Comparable to patients with McArdle disease, the patient developed a 'second wind' with a spontaneous fall in exercise heart rate and perceived exertion. Like in McArdle disease, this was attributable to an increase in muscle oxidative capacity. Carbohydrate oxidation was blocked during exercise, and the patient had exaggerated oxidation of fat to fuel exercise. Exercise heart rate and perceived exertion were lower after IV glucose and oral sucrose. Muscle glycogen level was low normal.

CONCLUSIONS

The second wind phenomenon has been considered to be pathognomonic for McArdle disease, but we demonstrate that it can also be present in PGM1 deficiency. We show that severe loss of PGM1 activity causes blocked muscle glycogenolysis that mimics McArdle disease, but may also limit glycogen synthesis, which broadens the phenotypic spectrum of this disorder.

MRC Centre Neuromuscular Biobank (Newcastle and London): Supporting and facilitating rare and neuromuscular disease research worldwide

Neuromuscular diseases are both genetic and acquired conditions resulting in progressive muscle weakness and wasting which lead to disability and reduced survival. The availability of high-quality human biomaterial is crucial to support biomedical research with potential applications at all stages of development, from molecular pathophysiology to drug discovery, clinical trials and evaluation of biomarkers. Although significant progress has been made over the last few years in the diagnosis of these rare conditions, the genetic defect and underlying pathological abnormality remain unknown in approximately 1/3 of cases. Moreover, to date no definitive cure is available for most neuromuscular disorders, nor are there sufficiently reliable and specific biomarkers to monitor disease progression and response to treatment. This is in part due to the rarity and genetic heterogeneity of neuromuscular diseases and the lack of access to patient samples. The availability of the national MRC Centre Biobank for Neuromuscular Diseases in Newcastle and London has addressed this bottleneck and supported neuromuscular research. Nine years after the establishment of the MRC Centre Biobank, many high profile research publications have highlighted the positive impact of neuromuscular biobanking for translational research and proven this facility to be a unique repository source for diagnostics, basic science research, industry, drug development, and therapy.

Avascular necrosis in children with cerebral palsy after reconstructive hip surgery

PURPOSE

Progressive hip displacement is one of the most common orthopaedic pathologies in children with cerebral palsy (CP). Reconstructive hip surgery has become the standard treatment of care. Reported avascular necrosis (AVN) rates for hip reconstructive surgery in these patients vary widely in the literature. The purpose of this study is to identify the frequency and associated risk factors of AVN for reconstructive hip procedures.

METHODS

A retrospective analysis was performed of 70 cases of reconstructive hip surgery in 47 children with CP, between 2009 and 2013. All 70 cases involved varus derotation osteotomy (VDRO), with 60% having combined VDRO and pelvic osteotomies (PO), and 21% requiring open reductions. Mean age at time of surgery was 8.82 years and 90% of patients were Gross Motor Function Classification System (GMFCS) 4 and 5. Radiographic dysplasia parameters were analysed at selected intervals, to a minimum of one year post-operatively. Severity of AVN was classified by Kruczynski's method. Bivar- iate statistical analysis was conducted using Chi-square test and Student's t-test.

RESULTS

There were 19 (27%) noted cases of AVN, all radio- graphically identifiable within the first post-operative year. The majority of AVN cases (63%) were mild to moderate in severity. Pre-operative migration percentage (MP) (p = 0.0009) and post-operative change in MP (p = 0.002) were the most significant predictors of AVN. Other risk factors were: GMFCS level (p = 0.031), post-operative change in NSA (p = 0.02) and concomitant adductor tenotomy (0.028).

CONCLUSION

AVN was observed in 27% of patients. Severity of displacement correlates directly with AVN risk and we suggest that hip reconstruction, specifically VDRO, be performed early in the 'hip at risk' group to avoid this complication.

A homozygous DPM3 mutation in a patient with alpha-dystroglycan-related limb girdle muscular dystrophy

Defects of O-linked glycosylation of alpha-dystroglycan cause a wide spectrum of muscular dystrophies ranging from severe congenital muscular dystrophy associated with abnormal brain and eye development to mild limb girdle muscular dystrophy. We report a female patient who developed isolated pelvic girdle muscle weakness and wasting, which became symptomatic at age 42. Exome sequencing uncovered a homozygous c.131T > G (p.Leu44Pro) substitution in DPM3, encoding dolichol-P-mannose (DPM) synthase subunit 3, leading to a 50% reduction of enzymatic activity. Decreased availability of DPM as an essential donor substrate for protein O-mannosyltransferase (POMT) 1 and 2 explains defective skeletal muscle alpha-dystroglycan O-glycosylation. Our findings show that DPM3 mutations may lead to an isolated and mild limb girdle muscular dystrophy phenotype without cardiomyopathy.

Abstract P145: Renal Inflammation and Injury is Associated with Increased Lymphangiogenesis in Hypertension

Hypertension is associated with immune system activation and inflammation. Renal infiltration of both innate and adaptive immune cells contributes to injury, dysfunction, and increased blood pressure. Activated immune cells that exit blood vessels into the interstitium then travel through lymphatic vessels to draining lymph nodes where they signal to other immune cells to increase the immune response. It is unknown how renal lymphatic vessels change in the context of hypertension, immune system activation, inflammation, and injury. We hypothesized that renal macrophage infiltration, inflammation, and injury would significantly increase lymphangiogenesis in various strains of rats. SHR rats that exhibit hypertension and renal injury (SHR-A3 strain) had significantly increased numbers of renal lymphatic vessels at 40 weeks of age compared to WKY controls (total of 3 fields of view: 52 ± 1 vs. 28 ± 1; p<0.05). This was associated with increased renal macrophage infiltration. SHR rats that exhibit hypertension but minimal renal injury (SHR-B2 strain) had significantly less renal lymphatic vessel numbers compared to WKY controls (25 ± 2 vs. 28 ± 1; p<0.05) and normal levels of macrophages. The signals for lymphangiogenesis, VEGF-C and its receptor VEGF-R3, were both increased significantly at the protein level in the kidneys of SHR-A3 rats at 18 weeks but not different in the kidneys of SHR-B2 rats compared to WKY controls. To test whether the increased lymphangiogensis is due to hypertension and/or renal inflammation and injury, we obtained kidneys from Fischer 344 rats that exhibit normal blood pressure but develop renal inflammation and injury as they age. Compared to kidneys from control 4-month old Fischer rats, kidneys from 20-month and 24-month old Fischer rats had significantly increased numbers of lymphatic vessels (32 ± 3 vs. 74 ± 1 vs. 110 ± 6, respectively; p<0.05) and this was also associated with increased macrophage infiltration. Protein levels of VEGF-C and VEGF-R3 were increased significantly in 20-month old Fischer rats compared to 4-month old controls. These data together demonstrate that renal immune cell infiltration, inflammation, and injury increases lymphangiogenesis.