Statistical analysis of observational studies in disability research.

Observational studies have a critical role in disability research, providing the opportunity to address a range of research questions. Over the past decades, there have been substantial shifts and developments in statistical methods for observational studies, most notably for causal inference. In this review, we provide an overview of modern design and analysis concepts critical for observational studies, drawing examples from the field of disability research and highlighting the challenges in this field, to inform the readership on important statistical considerations for their studies.

The association between human chorionic gonadotropin and adverse pregnancy outcomes: a systematic review and meta-analysis.

OBJECTIVE: This study aimed to evaluate the association between human chorionic gonadotropin and adverse pregnancy outcomes. DATA SOURCES: Medline, Embase, PubMed, and Cochrane were searched in November 2021 using Medical Subject Headings (MeSH) and relevant key words. STUDY ELIGIBILITY CRITERIA: This analysis included published full-text studies of pregnant women with serum human chorionic gonadotropin testing between 8 and 28 weeks of gestation, investigating fetal outcomes (fetal death in utero, small for gestational age, preterm birth) or maternal factors (hypertension in pregnancy: preeclampsia, pregnancy-induced hypertension, placental abruption, HELLP syndrome, gestational diabetes mellitus). METHODS: Studies were extracted using REDCap software. The Newcastle-Ottawa scale was used to assess for risk of bias. Final meta-analyses underwent further quality assessment using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) method. RESULTS: A total of 185 studies were included in the final review, including the outcomes of fetal death in utero (45), small for gestational age (79), preterm delivery (62), hypertension in pregnancy (107), gestational diabetes mellitus (29), placental abruption (17), and HELLP syndrome (2). Data were analyzed separately on the basis of categorical measurement of human chorionic gonadotropin and human chorionic gonadotropin measured on a continuous scale. Eligible studies underwent meta-analysis to generate a pooled odds ratio (categorical human chorionic gonadotropin level) or difference in medians (human chorionic gonadotropin continuous scale) between outcome groups. First-trimester low human chorionic gonadotropin levels were associated with preeclampsia and fetal death in utero, whereas high human chorionic gonadotropin levels were associated with preeclampsia. Second-trimester high human chorionic gonadotropin levels were associated with fetal death in utero and preeclampsia. CONCLUSION: Human chorionic gonadotropin levels are associated with placenta-mediated adverse pregnancy outcomes. Both high and low human chorionic gonadotropin levels in the first trimester of pregnancy can be early warning signs of adverse outcomes. Further analysis of human chorionic gonadotropin subtypes and pregnancy outcomes is required to determine the diagnostic utility of these findings in reference to specific cutoff values.

Distinct manifestations and potential mechanisms of seizures due to cortical versus white matter injury in children.

PURPOSE: To study seizure manifestations and outcomes in children with cortical versus white matter injury, differences potentially explaining variability of epilepsy in children with cerebral palsy. METHODS: In this population-based retrospective cohort study, MRIs of children with cerebral palsy due to ischemia or haemorrhage were classified according to presence or absence of cortical injury. MRI findings were then correlated with history of neonatal seizures, seizures during childhood, epilepsy syndromes, and seizure outcomes. RESULTS: Of 256 children studied, neonatal seizures occurred in 57 and seizures during childhood occurred in 93. Children with neonatal seizures were more likely to develop seizures during childhood, mostly those with cortical injury. Cortical injury was more strongly associated with (1) developing seizures during childhood, (2) more severe epilepsy syndromes (infantile spasms syndrome, focal epilepsy, Lennox-Gastaut syndrome), and (3) less likelihood of reaching > 2 years without seizures at last follow-up, compared to children without cortical injury. Children without cortical injury, mainly those with white matter injury, were less likely to develop neonatal seizures and seizures during childhood, and when they did, epilepsy syndromes were more commonly febrile seizures and self-limited focal epilepsies of childhood, with most achieving > 2 years without seizures at last follow-up. The presence of cortical injury also influenced seizure occurrence, severity, and outcome within the different predominant injury patterns of the MRI Classification System in cerebral palsy, most notably white matter injury. CONCLUSIONS: Epileptogenesis is understood with cortical injury but not well with white matter injury, the latter potentially related to altered postnatal white matter development or myelination leading to apoptosis, abnormal synaptogenesis or altered thalamic connectivity of cortical neurons. These findings, and the potential mechanisms discussed, likely explain the variability of epilepsy in children with cerebral palsy and epilepsy following early-life brain injury in general.

Confounding-adjustment methods for the causal difference in medians.

BACKGROUND: With continuous outcomes, the average causal effect is typically defined using a contrast of expected potential outcomes. However, in the presence of skewed outcome data, the expectation (population mean) may no longer be meaningful. In practice the typical approach is to continue defining the estimand this way or transform the outcome to obtain a more symmetric distribution, although neither approach may be entirely satisfactory. Alternatively the causal effect can be redefined as a contrast of median potential outcomes, yet discussion of confounding-adjustment methods to estimate the causal difference in medians is limited. In this study we described and compared confounding-adjustment methods to address this gap. METHODS: The methods considered were multivariable quantile regression, an inverse probability weighted (IPW) estimator, weighted quantile regression (another form of IPW) and two little-known implementations of g-computation for this problem. Methods were evaluated within a simulation study under varying degrees of skewness in the outcome and applied to an empirical study using data from the Longitudinal Study of Australian Children. RESULTS: Simulation results indicated the IPW estimator, weighted quantile regression and g-computation implementations minimised bias across all settings when the relevant models were correctly specified, with g-computation additionally minimising the variance. Multivariable quantile regression, which relies on a constant-effect assumption, consistently yielded biased results. Application to the empirical study illustrated the practical value of these methods. CONCLUSION: The presented methods provide appealing avenues for estimating the causal difference in medians.

Emotional behavioral outcomes of children with unilateral and mild hearing loss.

Background: Deaf and hard-of hearing (DHH) children often experience emotional/behavioral difficulties. The impact of unilateral/mild hearing loss (HL) on children's emotion and behavior are unclear. We aimed to describe emotional/behavioral, health related quality-of-life (HRQoL) and parent psychological distress outcomes of school-age children with unilateral/mild HL, compared to children with moderate to profound HL, and in relation to population norms; and identify predictive factors of emotional/behavioral difficulties. Methods: Data of 339 DHH children, 5-12 years, enrolled in the Victorian Childhood Hearing Longitudinal Databank (VicCHILD), which include demographics, early development, medical/audiological characteristics and parent rated questionnaires of emotion/behavior, HRQoL and parental psychological distress collected at various stages of child's life were analyzed. We used Cohen's d to investigate the outcomes by measuring the mean score differences of both groups with published norms and logistic regression to analyze the factors predictive of emotional/behavioral difficulties. Results: The proportion of children with unilateral/mild HL and moderate to profound HL who experienced emotional/behavioral difficulties was similar (18.3% vs. 20.6%), with hyperactivity and poor prosocial behavior reported as the predominant symptoms in both groups. Mean emotional/behavioral scores of both groups were comparable and substantially higher than normative population scores. This was also the case for HRQoL and levels of parent distress. Among children with unilateral/mild HL, additional health needs were the strongest predictive factor, demonstrating an approximately 1.7-fold increase in odds of emotional/behavioral difficulties (OR = 1.67; 95% CI 1.29-2.17, p < 0.001) with every additional health need. Early developmental concerns, other than communication milestone and attending mainstream schoolshowed weaker evidence of association. Conclusion: Children with unilateral/mild HL were just as likely as those with moderate to profound HL to experience more emotional/behavioral difficulties, poorer HRQoL and higher parental distress scores compared to population norms. Our findings justify the provision of early intervention, support and medical services for all DHH children to identify those at risk of poorer outcomes.

Language and health-related quality of life outcomes of children early-detected with unilateral and mild bilateral hearing loss.

Introduction: We aimed to describe the language and health-related quality of life (HRQoL) outcomes of children early-identified with unilateral or mild bilateral permanent hearing loss. This was a cross-sectional community-based study of children with mild bilateral or unilateral permanent hearing loss (including unilateral auditory neuropathy spectrum disorder (ANSD)), drawn from a population-based databank in Victoria, Australia. Methods: Enrolment in this databank is independent of early intervention and amplification approaches. Language and caregiver-reported HRQoL outcomes are described by type and degree of loss at three timepoints across child development: at age 2 years (n = 255), 5-7 years (n = 173) and 9-12 years (n = 45). Results: Across all age groups, average language outcomes were poorer than population normative scores by between a half to two thirds of a standard deviation. Children with mild bilateral hearing loss demonstrated poorer average language outcomes than children with unilateral hearing loss, particularly at younger ages. Children with unilateral ANSD showed language outcomes comparable to their peers with unilateral profound hearing loss. Children had poorer HRQoL psychosocial scores compared to physical scores, without obvious patterns of outcomes linked to degree or type of hearing loss. Discussion: This study demonstrates children with early-identified unilateral or mild bilateral hearing loss have average language and HRQoL outcomes poorer than population normative expectations from an early age. These outcomes are observed at later ages across childhood. These findings provide a contemporary description of language and quality of life outcomes for children identified but not targeted by universal newborn hearing screening and raise questions of how to provide better support for these populations of children and their families.

Socio-Emotional Experiences and Wellbeing of Deaf and Hard of Hearing Children and Their Parents before and during the COVID-19 Pandemic.

Deaf and hard of hearing (DHH) children in Victoria, Australia, were exposed to strict public health restrictions, including sustained lockdowns, during the COVID-19 pandemic. DHH children have higher health and socio-emotional needs than their hearing peers. We aimed to (1) describe the socio-emotional experiences of DHH children and their parents and (2) compare child and parent socio-emotional wellbeing, before and during the COVID-19 pandemic. Between May and September 2020, 497 (62%) parents of DHH children from the Victorian Childhood Hearing Longitudinal Databank completed an online survey. Measures were drawn from the CoRonavIruS Health Impact Survey (CRISIS) v3.0. Data were summarized using descriptive statistics to compare outcomes before and during the pandemic. Parents reported their children to have more negative socio-emotional wellbeing (mean emotions/worries score, EWS, changed from 0.76 pre-pandemic to 1.10 during the pandemic, mean difference 0.34, 95% CI: 0.28 to 0.39), regardless of the type or severity of hearing loss. Parents also had more negative socio-emotional wellbeing (mean EWS changed from 1.05 pre-pandemic to 1.43 during the pandemic, mean difference 0.38, 95% CI: 0.31 to 0.44). Negative socio-emotional experiences co-occurred with large social changes during the pandemic. Additional services should support the socio-emotional wellbeing of DHH children during significant adverse childhood experiences.

Spoken Expressive Vocabulary in 2-Year-Old Children with Hearing Loss: A Community Study.

Through a cross-sectional community study of 2044 children aged 2 years, we (1) examine the impact of hearing loss on early spoken expressive vocabulary outcomes and (2) investigate how early intervention-related factors impact expressive vocabulary outcomes in children with hearing loss predominantly identified through universal newborn hearing screening. We used validated parent/caregiver-reported checklists from two longitudinal cohorts (302 children with unilateral or bilateral hearing loss, 1742 children without hearing loss) representing the same population in Victoria, Australia. The impact of hearing loss and amplification-related factors on vocabulary was estimated using g-computation and multivariable linear regression. Children with versus without hearing loss had poorer expressive vocabulary scores, with mean scores for bilateral loss 0.5 (mild loss) to 0.9 (profound loss) standard deviations lower and for unilateral loss marginally (0.1 to 0.3 standard deviations) lower. For children with hearing loss, early intervention and amplification by 3 months, rather than by 6 months or older, resulted in higher expressive vocabulary scores. Children with hearing loss demonstrated delayed spoken expressive vocabulary despite whole-state systems of early detection and intervention. Our findings align with calls to achieve a 1-2-3 month timeline for early hearing detection and intervention benchmarks for screening, identification, and intervention.

Using machine-learning methods to identify early-life predictors of 11-year language outcome.

BACKGROUND: Language is foundational for neurodevelopment and quality of life, but an estimated 10% of children have a language disorder at age 5. Many children shift between classifications of typical and low language if assessed at multiple times in the early years, making it difficult to identify which children will have persisting difficulties and benefit most from support. This study aims to identify a parsimonious set of preschool indicators that predict language outcomes in late childhood, using data from the population-based Early Language in Victoria Study (n = 839). METHODS: Parents completed surveys about their children at ages 8, 12, 24, and 36 months. At 11 years, children were assessed using the Clinical Evaluation of Language Fundamentals 4th Edition (CELF-4). We used random forests to identify which of the 1990 parent-reported questions best predict children's 11-year language outcome (CELF-4 score ≤81 representing low language) and used SuperLearner to estimate the accuracy of the constrained sets of questions. RESULTS: At 24 months, seven predictors relating to vocabulary, symbolic play, pragmatics and behavior yielded 73% sensitivity (95% CI: 57, 85) and 77% specificity (95% CI: 74, 80) for predicting low language at 11 years. [Corrections made on 5 May 2023, after first online publication: In the preceding sentence 'motor skills' has been corrected to 'behavior' in this version.] At 36 months, 7 predictors relating to morphosyntax, vocabulary, parent-child interactions, and parental stress yielded 75% sensitivity (95% CI: 58, 88) and 85% specificity (95% CI: 81, 87). Measures at 8 and 12 months yielded unsatisfactory accuracy. CONCLUSIONS: We identified two short sets of questions that predict language outcomes at age 11 with fair accuracy. Future research should seek to replicate results in a separate cohort.

Survival of individuals with cerebral palsy in Victoria, Australia: A longitudinal cohort study spanning four decades.

AIM: To provide an updated description of the rates, trends, and predictors of mortality of individuals with cerebral palsy (CP), born in the Australian state of Victoria between 1970 and 2012. METHOD: Data were extracted for 4807 individuals (2091 females; 2716 males). The probability of survival to 30th June 2017 was calculated using the Kaplan-Meier method. Mortality rates were calculated per 1000 person-years using age strata and compared with population mortality rates to produce mortality ratios. Cox proportional hazards regression was used to calculate hazard ratios for selected demographic and clinical characteristics and to estimate the effect of birth epoch on 15-year survival. RESULTS: There were 666 recorded deaths. Compared to the general population, mortality was higher for all persons with CP and highest for children aged 1 to 15 years (45-62 times). We observed 35% improvement in the probability of survival to 15 years for births in the 2000s relative to the 1970s (hazard ratio 0.65, 95% confidence interval [CI] 0.49, 0.86), but only 4% improvement for the subgroup with complex CP (hazard ratio 0.96, 95% CI 0.69, 1.33). INTERPRETATION: The observed improvements in survival for those born in the 2000s is likely related predominantly to a proportional reduction in complex CP within the cohort. WHAT THIS PAPER ADDS: Length of survival improved for Australians with cerebral palsy (CP) born this millennium. Improved survival was mainly because of a proportional reduction in complex CP. A small improvement in length of survival was seen for children with complex CP.

Etiology, Comorbidities, and Health Service Use in a Clinical Cohort of Children With Hearing Loss.

OBJECTIVE: To examine etiology, comorbidities, and health service use in a cohort of children with permanent hearing loss. Receiving an etiological diagnosis can inform reproductive planning, rehabilitation outcomes, predict additional disabilities, and direct intervention or management decisions. DESIGN: Retrospective audit of 518 deaf/hard-of-hearing children attending a tertiary pediatric outpatient clinic (2016-2019) using descriptive statistics. We used linear regression to investigate the relationship between degree of hearing loss, comorbidities, and health service use. RESULTS: Of the 518 children who attended the clinic, 481 (92.9%) proceeded with testing for etiology. Most children (399/518, 77.0%) were diagnosed with hearing loss by 3 mo of age. Of the children tested, the cause of hearing loss was confirmed in 234/481 (48.6%), suspected in 113/481 (23.5%), and unknown in 134/481 (27.9%); 17/341 (5.0%) had congenital cytomegalovirus (CMV), 17/320 (5.3%) had enlarged vestibular aqueducts, 67/213 (31.5%) of children with bilateral hearing loss had connexin mutation, and 25/72 (34.7%) of children with unilateral loss had hypoplastic/absent cochlear nerve on imaging. The odds of having a definitive/suspected diagnosis were twice as likely for indivduals with profound hearing loss than mild hearing loss (OR 2.1; 95% CI, 1.2-3.9; P = 0.02). The majority (348/518, 67.2%) of children had medical comorbidities, and most children attended otolaryngology (453/518, 87.5%), early intervention (358/518, 69.1%), and genetic (287/518, 55.4%) services. CONCLUSIONS: Children with hearing loss have diverse etiologies, most have comorbidities, and attend multiple services. Most families elected to proceed with diagnostic testing for etiology. Current guidelines and expanded access to genetic testing identified a confirmed/suspected etiological diagnosis in 72.1% of children tested. The number of comorbidities correlated with service use, regardless of hearing loss severity.

Predictors of Early Language Outcomes in Children with Connexin 26 Hearing Loss across Three Countries.

GJB2-associated hearing loss (GJB2-HL) is the most common genetic cause of hearing loss in children. However, little is known about the clinical characteristics and early language outcomes in population-oriented samples including children with different degrees of hearing loss. Insight into these characteristics are relevant for the counselling of parents. Our sample consisted of 66 children at approximately 2 years of age (17-32 months) with bilateral hearing loss due to GJB2 from three population-based cohorts in Austria, Australia and the Netherlands. Predictors of early vocabulary, including demographic, audiological, genetic and intervention variables and the role of medical comorbidities and nonverbal cognition were examined. The vocabulary scores of children with GJB2-HL were approximately 0.7 standard deviations (SDs) below the norms of children with typical hearing. Age at access to family-centered early intervention and first-born position among siblings predicted language outcomes, whereas the degree of hearing loss and genetic subtype were not significantly correlated with expressive vocabulary. In children with GJB2-HL, early access to family-centered early intervention significantly affected language outcomes at the age of two.

Establishing consensus for the assessment of chronic pain in children and young people with cerebral palsy: a Delphi study.

PURPOSE: Inconsistent and inadequate pain assessment practices in cerebral palsy (CP) have resulted from a lack of standardisation of pain assessment, limited use of appropriate tools and failure to integrate disability and biopsychosocial models. To assist with improving consistency, this study aimed to establish consensus from key stakeholders regarding domains considered essential for measuring chronic pain in children and young people with CP. METHOD: A modified electronic Delphi study was conducted on 83 stakeholders, including clinicians, researchers, people with CP and parents of children with CP. Participants rated 18 domains sourced from existing literature as either "core", "recommended", "exploratory" or "not required". RESULTS: After two rounds of surveys, 12 domains were considered core: pain location, pain frequency, pain intensity, changeable factors, impact on emotional wellbeing, impact on participation, pain communication, influence on quality of life, physical impacts, sleep, pain duration and pain expression. CONCLUSION: These domains reflect the complexity of pain in a heterogeneous population where medical comorbidities are common and communication and intellectual limitations impact significantly on the ability of many to self-report. The domains will be utilised to build a framework of pain assessment specific to children and young people with CP guided by the biopsychosocial model.Implications for rehabilitationChronic pain is under-identified and poorly assessed in the cerebral palsy (CP) population.The perspectives of clinicians, researchers and consumers are vital for developing a framework for chronic pain assessment in CP.Consensus of key stakeholders found 12 domains considered essential to incorporate into a chronic pain assessment model in CP.

Social Outcomes of School Leavers With Cerebral Palsy Living in Victoria.

Objective: In Australia, the National Disability Strategy provides a framework to guide actions and investment to achieve equity in social inclusion and economic participation for people with disability. We investigated the social outcomes of school leavers with cerebral palsy (CP) in Victoria, Australia and explored the determinants of desirable outcomes. Methods: We used the Victorian CP Register to invite all adults with CP aged 18-25 years (n = 649). On-line and/or paper-based surveys explored participation in education, employment, community activities, living situation, relationships and life satisfaction. Functional and health status data were collected. Social outcomes were summarized descriptively and compared between individuals with CP and non-disabled peers aged 18-25 years from the Household Income and Labor Dynamics in Australia dataset. Within the CP cohort we explored whether physical and mental health and level of functioning were associated with social outcomes. In addition, a descriptive comparison was undertaken between the social outcomes of the current CP cohort with that of a previously reported 2007 cohort. Results: Ninety participants (57% male; mean age 22.4 years (SD: 2.2) in 2020; 61.1% self-reported) provided data for analyses; response rate 16.9%. CP characteristics were similar between respondents and non-respondents. In comparison to similar aged peers, 79.8% had completed secondary school (compared to 83.2%); 32.6% (compared to 75.8%) were in paid work; 87.5% (compared to 48.2%) were living in their parental home; and 3.4% (compared to 31.6%) were married or partnered. Individuals with CP and higher levels of functional capacity and better physical health were more likely to undertake post-secondary education. Higher levels of functional capacity and physical health, as well as lower mental health status were associated with being employed. Conclusions: While foundational education completion rates were similar to non-disabled peers, significant gaps in social outcomes remain, including residence in the parental home and single status. While addressing these issues is challenging, substantial efforts are needed to reduce these disparities-work that needs to be done in collaboration with people with CP and their families.

Second trimester maternal serum biomarkers and the risk of cerebral palsy.

AIMS: To investigate whether second trimester maternal serum screening (2TMSS) biomarkers are associated with cerebral palsy (CP) and identify CP characteristics associated with abnormal biomarker levels. METHOD: In this retrospective case-control data linkage study, we linked mothers of 129 singleton CP cases from a population register to their 2TMSS records and selected 10 singleton pregnancy controls per case (n = 1290). We compared mean and abnormal levels of alpha-fetoprotein (AFP), beta subunit of human chorionic gonadotrophin (ß-hCG), unconjugated estriol (uE3), and inhibin between cases and controls and within CP subgroups. RESULTS: Compared to control pregnancies, CP pregnancies had higher mean levels of AFP (1.10 vs. 1.01 multiple of the population median [MoM], p = 0.01) and inhibin (1.10 vs. 0.98 MoM, p ≤ 0.01). CP pregnancies were 2.5 times more likely to be associated with high levels of AFP (OR 2.52 [95% confidence interval [CI] 1.30, 4.65]; p < 0.01) and 2.6 times for inhibin (OR 2.63 [95% CI 1.37, 4.77]; p < 0.01), and 6.8 times when AFP and inhibin were both elevated (OR 6.75 [95% CI 2.41, 18.94]; p < 0.01). In CP cases, high AFP and high inhibin levels were associated with preterm birth and low birthweight. INTERPRETATION: Abnormal second-trimester biomarker levels suggest abnormal placentation plays a role in the causal pathway of some CP cases.

First-trimester maternal serum biomarkers and the risk of cerebral palsy.

AIM: To investigate whether combined first-trimester screening (cFTS) biomarkers are associated with cerebral palsy (CP) and to identify CP characteristics associated with abnormal biomarker levels. METHOD: In this retrospective case-control data linkage study, we matched mothers of 435 singletons with CP from a population register to their cFTS records and selected 10 singleton pregnancy controls per case. We compared mean and abnormal levels (expressed as multiples of the median [MoMs]) of pregnancy-associated plasma protein-A (PAPP-A), beta subunit of human chorionic gonadotrophin (ß-hCG), and nuchal translucency between cases and controls and between CP subgroups. RESULTS: Compared with control pregnancies, CP pregnancies had lower mean levels of PAPP-A (0.95 vs 1.01 MoM, p=0.02) and ß-hCG (0.93 vs 0.99 MoM, p=0.02). Biomarker levels in CP pregnancies were 1.8 times more likely to be associated with abnormally low levels of PAPP-A (p<0.01), 1.4 times for ß-hCG (p=0.12), and 2.6 times for low PAPP-A and ß-hCG together (p=0.04). In cases with CP, an abnormally low PAPP-A level was associated with moderate preterm birth, low Apgar scores, and Gross Motor Function Classification System level V. Low ß-hCG was associated with very low birthweight. INTERPRETATION: Low first-trimester biomarker levels suggest a role for early pregnancy factors in some causal pathways to CP. WHAT THIS PAPER ADDS: Low first-trimester levels of biomarkers in maternal serum are associated with later cerebral palsy (CP). Early pregnancy factors have potential importance in causal pathways to CP. Causal pathways involving preterm birth, term neonatal encephalopathy, and genetic syndromes may be implicated.

Divergence exists in the subcellular distribution of intramuscular triglyceride in human skeletal muscle dependent on the choice of lipid dye.

Despite over 50 years of research, a comprehensive understanding of how intramuscular triglyceride (IMTG) is stored in skeletal muscle and its contribution as a fuel during exercise is lacking. Immunohistochemical techniques provide information on IMTG content and lipid droplet (LD) morphology on a fibre type and subcellular-specific basis, and the lipid dye Oil Red O (ORO) is commonly used to achieve this. BODIPY 493/503 (BODIPY) is an alternative lipid dye with lower background staining and narrower emission spectra. Here we provide the first quantitative comparison of BODIPY and ORO for investigating exercise-induced changes in IMTG content and LD morphology on a fibre type and subcellular-specific basis. Estimates of IMTG content were greater when using BODIPY, which was predominantly due to BODIPY detecting a larger number of LDs, compared to ORO. The subcellular distribution of intramuscular lipid was also dependent on the lipid dye used; ORO detects a greater proportion of IMTG in the periphery (5 µm below cell membrane) of the fibre, whereas IMTG content was higher in the central region using BODIPY. In response to 60 min moderate-intensity cycling exercise, IMTG content was reduced in both the peripheral (- 24%) and central region (- 29%) of type I fibres (P < 0.05) using BODIPY, whereas using ORO, IMTG content was only reduced in the peripheral region of type I fibres (- 31%; P < 0.05). As well as highlighting some methodological considerations herein, our investigation demonstrates that important differences exist between BODIPY and ORO for detecting and quantifying IMTG on a fibre type and subcellular-specific basis.

Growth Trajectories in Genetic Subtypes of Prader-Willi Syndrome.

Prader-Willi syndrome (PWS) is a rare disorder caused by the loss of expression of genes on the paternal copy of chromosome 15q11-13. The main molecular subtypes of PWS are the deletion of 15q11-13 and non-deletion, and differences in neurobehavioral phenotype are recognized between the subtypes. This study aimed to investigate growth trajectories in PWS and associations between PWS subtype (deletion vs. non-deletion) and height, weight and body mass index (BMI). Growth data were available for 125 individuals with PWS (63 males, 62 females), of which 72 (57.6%) had the deletion subtype. There was a median of 28 observations per individual (range 2-85), producing 3565 data points distributed from birth to 18 years of age. Linear mixed models with cubic splines, subject-specific random effects and an autoregressive correlation structure were used to model the longitudinal growth data whilst accounting for the nature of repeated measures. Height was similar for males in both PWS subtypes, with non-deletion females being shorter than deletion females for older ages. Weight and BMI were estimated to be higher in the deletion subtype compared to the non-deletion subtype, with the size of difference increasing with advancing age for weight. These results suggest that individuals with deletion PWS are more prone to obesity.