Estimating the Epidemic Size of Superspreading Coronavirus Outbreaks in Real Time: Quantitative Study

BACKGROUND

Novel coronaviruses have emerged and caused major epidemics and pandemics in the past 2 decades, including SARS-CoV-1, MERS-CoV, and SARS-CoV-2, which led to the current COVID-19 pandemic. These coronaviruses are marked by their potential to produce disproportionally large transmission clusters from superspreading events (SSEs). As prompt action is crucial to contain and mitigate SSEs, real-time epidemic size estimation could characterize the transmission heterogeneity and inform timely implementation of control measures.

OBJECTIVE

This study aimed to estimate the epidemic size of SSEs to inform effective surveillance and rapid mitigation responses.

METHODS

We developed a statistical framework based on back-calculation to estimate the epidemic size of ongoing coronavirus SSEs. We first validated the framework in simulated scenarios with the epidemiological characteristics of SARS, MERS, and COVID-19 SSEs. As case studies, we retrospectively applied the framework to the Amoy Gardens SARS outbreak in Hong Kong in 2003, a series of nosocomial MERS outbreaks in South Korea in 2015, and 2 COVID-19 outbreaks originating from restaurants in Hong Kong in 2020.

RESULTS

The accuracy and precision of the estimation of epidemic size of SSEs improved with longer observation time; larger SSE size; and more accurate prior information about the epidemiological characteristics, such as the distribution of the incubation period and the distribution of the onset-to-confirmation delay. By retrospectively applying the framework, we found that the 95% credible interval of the estimates contained the true epidemic size after 37% of cases were reported in the Amoy Garden SARS SSE in Hong Kong, 41% to 62% of cases were observed in the 3 nosocomial MERS SSEs in South Korea, and 76% to 86% of cases were confirmed in the 2 COVID-19 SSEs in Hong Kong.

CONCLUSIONS

Our framework can be readily integrated into coronavirus surveillance systems to enhance situation awareness of ongoing SSEs.

Ultrasound as the first line investigation for midgut malrotation: a UK tertiary centre experience

AIM

To present the first 22-months experience of transitioning to an ultrasound-first pathway for suspected midgut malrotation.

MATERIALS AND METHODS

An "ultrasound-first" imaging pathway was initiated in October 2021. Twenty-two-months later, a search was undertaken of all <1-year-old patients with "bilious", "malrotation," or "volvulus" as the imaging indication. Reports and images from upper gastrointestinal fluoroscopy (UGI) and ultrasound were reviewed, and diagnoses and outcomes were documented.

RESULTS

The search yielded 101 eligible cases between October 2021 and July 2023. Of the patients, 63/101 (62%) had both ultrasound and UGI: 47/63 (75%) ultrasound first, 16/63 (25%) UGI first. Thirty-one per cent (31/101) had ultrasound only and 7/70 (10%) UGI only. The pathway diagnosed 7/8 (88%) infants with midgut malrotation with or without volvulus and one infant who had an inconclusive ultrasound examination with a suspected an internal hernia and who was found to have malrotation volvulus at surgery. Twenty-one infants who had confidently normal ultrasound examinations and who also had UGI all had a normal duodenojejunal flexure position. Ultrasound detected alternative pathology in eight children. Duodenal visualisation improved with time: 6/15 (40%) in the first 6 months to 23/34 (68%) after the first year.

CONCLUSION

The transition to ultrasound as the first diagnostic test for midgut malrotation can be done safely and effectively in a UK centre, which previously relied solely on UGI.

Targeted and non-targeted screening of flame retardants in rural and urban honey

Flame retardants (FRs) are often added to commercial products to achieve flammability resistance, but they are not chemically bonded to the materials, so, they can be easily released into the environment during the production and disposal processes. When honeybees travel to collect nectar during the pollination process, they are prone to be contaminated by chemicals in the air. Therefore, honey contamination has been proposed as an indicator of the pollution status in a particular region. To date, the occurrence of flame retardants in urban honey has yet to be explored. In this study, a direct injection method was used, coupled with LC-QTOF-MS, to analyze honey samples. This method was applied to urban (n = 100) and rural (n = 100) honey samples from the Quebec province (Canada), and the levels of flame retardants in urban and rural honey samples were not significantly different. In the targeted approach, two of the target FRs, tris(2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPHP), were detected and confirmed at an average trace concentration (<1 ng mL-1). Additionally, a non-targeted screening workflow with an in-house-built library was developed and validated to screen for flame retardants in honey. Tris (2-chloropropyl) phosphate (TCIPP) was identified in honey using the non-targeted screening workflow and confirmed using a pure analytical standard, but there are other compounds detected in the non-targeted analysis that have yet to be validated. This study was the first to report FR compounds based on a direct injection method, coupled with a non-targeted screening workflow, at a trace level in a honey matrix. It also showed that a non-targeted workflow was effective to detect and identify unknown compounds present in the honey sample; hence, this provided a novel angle for the occurrence of FRs in air, with honey as a bio-indicator.

Assessing the Readiness for Implementing the World Health Organization's ICOPE Approach in Hong Kong: Perspectives from Social Care and Policy Stakeholders

Although integrated care has been considered a key strategy in reforming health systems around the world, it seems hard to realise in practice, particularly in the part of medical social integration. Worse still, little is known about the capacity of social care professionals who implement it, or their perceived roles and responsibilities, as well as the barriers and facilitators that stakeholders from the health and social sectors identify as factors affecting the ICOPE implementation process. Therefore, the present study was performed to probe into these issues. Data were collected from an online survey based on the WHO ICOPE scorecard (N = 34), and focus groups with policy makers, managers, health and social care professionals (N = 47). Inductive analyses were performed in accordance with the service and system levels within the WHO ICOPE implementation framework. While the findings from the scorecard survey highlight the gap in actualizing the ICOPE approach within the existing social services and care structures, we found support for a model of integrated care underpinned by the WHO ICOPE approach. Factors that may hinder and facilitate ICOPE implementation include workforce capacity-building, coordinated networks and partnerships, and financial mechanisms. This finding can help inform subsequent actions that further support health and social care advancement and collaboration, and the implementation of the ICOPE approach.

A Dyadic Cooking-Based Intervention for Improving Subjective Health and Well-Being of Older Adults with Subjective Cognitive Decline and Their Caregivers: A Randomized Controlled Trial

OBJECTIVES

Evidence on the effectiveness of cooking activities as a well-being promotion intervention for older adults with subjective cognitive decline (SCD) and their caregivers is scarce. In view of this, a randomized controlled trial was conducted to examine whether a dyadic cooking-based intervention can improve the subjective health and well-being of older adults with SCD and their caregivers, as well as the cooking competence of the former group.

DESIGN

Randomized controlled trial.

SETTING

Community.

PARTICIPANTS

Sixty pairs of community-dwelling older adults aged 60 years or above with SCD (mean age = 78.4 years) and their caregivers (mean age = 65.3 years) were randomly assigned to the intervention group (N = 30 pairs) and the wait-list control group (N = 30 pairs).

INTERVENTION

The intervention was an innovative 5-week (two hours per week) dyadic cooking-based intervention employing procedural learning methods specifically adapted for older adults with SCD.

MEASUREMENTS

The outcome measures included 1) a well-being index composed by four indicators: life satisfaction, feeling of happiness, sense of purpose and meaning in life, and perceived health, and 2) cooking competence.

RESULTS

For both older adults with SCD and their caregivers, the increases in the well-being index were significantly greater in the intervention group than in the control group (β = 0.508, 95% CI [0.036, 0.980]). For older adults with SCD, the increases in the cooking competence score were significantly greater in the intervention group than in the control group (β = 1.629, 95% CI [0.165, 3.071]).

CONCLUSION

The dyadic cooking-based intervention resulted in improvements in the cooking competence and well-being of older adults with SCD, as well as the well-being of caregivers.

Trajectories of Intrinsic Capacity: Determinants and Associations with Disability

OBJECTIVES

Intrinsic capacity (IC) declines progressively with age, thereby increasing the risk of disability. However, it is less known whether IC trajectories are associated with disability. This study aims to identify the different patterns of IC trajectories in older people, and examine their determinants and associations with Instrumental Activities of Daily Living (IADL).

DESIGN

Cohort study.

SETTING

Community centres in different regions in Hong Kong.

PARTICIPANTS AND MEASUREMENTS

Longitudinal data from community-dwelling older people aged 60 years or above (n = 1371) collected between 2016 and 2021 was analysed. Their mean age was 74.5 years, and 78.7% of them were female. Repeated measurements of a set of 14 self-reported items were used to generate IC scores at four time points using a bi-factor model. Latent class growth analysis was performed to identify classes with distinct IC trajectories. The association between class membership and IADL disability was then examined using logistic regression.

RESULTS

Three distinct IC trajectories were identified. The 1st class included those with the highest level of baseline IC and the least declining trajectory, whereas the 3rd class was composed by those with the lowest level of baseline IC and the most declining trajectory. Older age, female gender, lower perceived financial adequacy, living in public or subsidized housing, and chronic diseases were associated with the 3rd class. After adjusting for demographic factors, socioeconomic status, and the number of chronic diseases, the 1st class was more likely to preserve IADL when compared against the 2nd class, with OR being 3.179 (95% CI: 2.152-4.793), whereas for the 3rd class, the OR was 0.253 (95% CI: 0.178-0.359).

CONCLUSION

Monitoring IC trajectories is of relevance to clinical practice, as it helps shift the focus from treating acute episodes of illness to preserving the functional ability of older people.

Moving towards the ICOPE Approach: Evaluation of Community-Based Intervention Activities on Improving Intrinsic Capacity

OBJECTIVES

Different types of community-based intervention activities may have differential effects in improving the intrinsic capacity (IC) of older people. This study aims to (i) identify subgroups of older people based on their IC impairments, (ii) examine the differential associations between different types of activity participations and change in IC across subgroups, and (iii) assess whether the activity participation patterns of older people align with the way that would benefit them the most.

METHODS

Participants were community-dwelling older people aged 60 years or above. They were screened for IC impairments at baseline, and their participation records of different types (cognitive, physical, nutritional, mental, and social) of intervention activities were collected for one year. An aggregated IC score was created based on four IC domains including cognitive (self-rated memory), locomotor (self-rated difficulties in walking), vitality (self-rated weight loss), and psychological (subjective well-being). Cluster analysis was used to group homogenous participants. Mixed-effects regression was used to examine the associations between activity counts (i.e., number of sessions participated) and change in IC. Activity participation patterns were also compared across subgroups.

RESULTS

Data were obtained from 7,357 participants (mean age = 74.72 years). Four clusters were identified, including those who were relatively robust (cluster 1, N = 4,380, 59.5%), those who had cognitive decline (cluster 2, N = 2,134, 29.0%), those who had impaired mobility and vitality (cluster 3, N = 319, 4.3%), and those with poor psychological well-being (cluster 4, N = 524, 7.1%). Overall, activity count was associated with IC improvement (β = 0.073, 95% CI [0.037, 0.108]). However, as regards the cluster-specific results, different types of activities were associated with IC improvement for different specific clusters. For instance, cognitive activity count was associated with IC improvement only for cluster 2 (β = 0.491, 95% CI [0.258, 0.732]). Notably, none of the activity types were associated with IC improvement for cluster 1. Regarding the activity participation patterns, there were no significant differences across the four clusters (Wilk's Λ = 0.997, F = 1.400, p = .138).

CONCLUSIONS AND IMPLICATIONS

IC improvement depended on the activity types and IC status of older people. In view of this, a people-centred and targeted approach should be adopted to maximize the overall benefits of intervention activities.

IL-7 and IL-7R regulate fetal macrophage establishment via survival and proliferation

We have recently reported that IL7R signaling regulates fetal macrophage development, in addition to lymphocyte lineage commitment and development. Specifically, IL7R deletion and pharmacological blockade during a defined fetal developmental window impairs the establishment of fetal macrophage populations in the liver, lung, brain, and epidermis. We next hypothesized that IL-7 is also required for fetal macrophage establishment and that IL-7 signaling activates developmental programs that facilitate macrophage development via proliferation and survival. Immunofluorescent staining of E14.5 murine embryos revealed abundant co-localized IL7R and F4/80 expression in fetal liver, lung, brain, and skin. IL7R+ F4/80-expressing cells were also found in close proximity to IL-7+ cells, suggesting they participate in IL-7 signaling. Moreover, germline deletion of IL-7 also resulted in postnatal depletion of fetal-derived macrophage populations. Antibody blockade of IL-7R receptor during late gestation revealed tissue-specific deficits in survival and proliferation the day before birth. Specifically, liver and lung macrophages showed increased apoptosis, as determined by Annexin V staining, while brain and epidermal macrophages were less proliferative, as determined by Ki67 staining. Here we have shown that IL-7, in addition to IL7R, regulates establishment of tissue-resident macrophages and that fetal blockade of IL7R signaling regulates establishment by impairing survival and proliferation during late gestation. Ongoing work seeks to define IL7/IL7R signaling pathways in developing macrophages, as well as use genetic models to pinpoint the requirement for IL7R in fetal myeloid specification.

Supported by grants from NIH (R01 10057561).

Towards Healthy Ageing: Using the Concept of Intrinsic Capacity in Frailty Prevention

OBJECTIVES

To examine whether intrinsic capacity (IC) could predict frailty, whether declines in specific domains of IC could lead to frailty, and whether different combinations of domains could represent different risks of developing frailty.

SETTING

Community.

PARTICIPANTS

Chinese people aged 65 years and older.

MEASUREMENTS

Using data from a prospective cohort study, we derived a summary score for IC and scores for the five domains (cognitive, locomotor, vitality, sensory, psychological) for each participant at baseline. Frailty was assessed according to the Fried's frailty phenotype at baseline, 2- and 4-year follow-ups. Participants were classified as frail if they had ≥3 of the following criteria: weight loss, self-rated exhaustion, weakness, slow walking speed, and low physical activity.

RESULTS

Four thousand participants were interviewed at baseline. Overall mean age was 72.5 years; 50% were women. Between baseline and the 2-year follow-up, 5.7% of non-frail participants developed frailty; between 2- and 4-year follow-ups, 5.7% of non-frail participants developed frailty. The average annual incidence rate of frailty was 2.9%. Higher scores on IC at baseline were associated with a lower risk of incident frailty at both follow-ups (year 2, odds ratio (OR)=0.64, 95% confidence interval (CI)=0.59-0.71); year 4, OR=0.64, 95%CI=0.58-0.71) after adjustment for age, sex, educational level, and chronic diseases. Across the five domains, vitality was the strongest predictor of incident frailty at each follow-up (year 2, OR=0.33, 95%CI=0.24-0.45; year 4, OR=0.33, 95%CI=0.23-0.46). Compared to other combinations of any two domains, having 'high' scores on both vitality and locomotor domains was associated with the lowest risk of incident frailty (year 2, OR=0.11, 95%CI=0.06-0.22, area under the curve (AUC)=0.770; year 4, OR=0.18, 95%CI=0.10-0.32, AUC=0.782).

CONCLUSION

This study provides evidence that IC was independently associated with incident frailty. It also finds that vitality was the domain most strongly associated with incident frailty. Finally, it suggests that optimizing multiple domains of IC, particularly vitality and locomotor, may prevent frailty.

676The impact of alcohol tax elimination policy on population health in Hong Kong

Background

Extensive research has shown that taxes on alcohol reduces consumption and alcohol-related harm. Uniquely among high-income economies, the Hong Kong Government reduced alcohol taxes on wine and beer by half in 2007; and entirely waived all alcohol-related taxes in 2008.

Methods

We adapted the International Model of Alcohol Harms and Policies (InterMAHP) using Hong Kong data to evaluate the health impact of the tax elimination policy changes on alcohol pricing. Prevalence and consumption estimates were calculated from serial Behavioural Risk Factor surveys of health behaviours among the Hong Kong population. We applied the linear approximation of the Almost Ideal Demand System (AIDS) econometric model to estimate the elasticity of demand for on-trade and off-trade sales of alcohol (beer, wine, and spirits) using Euromonitor market sales data. We derived population attributable fractions and relative risks estimates from Hospital Authority morbidity and mortality records.

Results

Alcohol consumption and alcohol-related harms were higher for males. We found the policy change increased alcohol-attributable mortalities, predominately due to increases in cancer, cardiovascular disease, and injuries. The burden of disease was higher in older age groups.

Conclusions

Hong Kong pursued a policy of eliminating taxes on alcohol despite extensive evidence on the effectiveness of taxation as a policy tool. We find empirical evidence this policy change was associated with an increase in alcohol-related harms and detrimental to population health.

Key messages

The alcohol tax elimination policy in Hong Kong was associated with an increase in alcohol-related burden of disease. Reintroduction of alcohol taxes merits consideration.

Neighborhood Social Cohesion Associates with Loneliness Differently among Older People According to Subjective Social Status

OBJECTIVES

To examine whether neighborhood social cohesion can alleviate the negative impact of low subjective social status on feelings of loneliness.

DESIGN

Cross-sectional study.

SETTING

Community, Hong Kong.

PARTICIPANTS

Older people who participated in a cohort study on osteoporosis and general health in Hong Kong (MrOs study).

METHODS

Data were sourced from the 14-year follow-up data of the MrOs study. Loneliness was measured using the 6-item De Jong Gierveld Loneliness Scale. Neighborhood social cohesion was measured by the Hong Kong version of Neighborhood Cohesion Instrument. Linear regression models were used to examine the associations between neighborhood social cohesion and loneliness, controlled for age, sex, marital status, educational level, lifestyle, number of diseases, and maximum lifetime income. The analyses were stratified by subjective social status as measured by a 10-rung self-anchoring scale.

RESULTS

1,037 participants with a mean age of 83 years were included in the study, of whom 72%, 83%, and 64% were classified as at risk of overall loneliness, emotional loneliness, and social loneliness, respectively. Those who were classified as at risk of overall loneliness reported lower subjective social status and had lower levels of neighborhood social cohesion. Linear regression models showed that higher levels of neighborhood social cohesion were associated with lower levels of overall and social loneliness. Stratified analyses showed that the associations between neighborhood social cohesion and loneliness vary across subjective social status groups. Among those with low/middle social status ranking, higher levels of neighborhood social cohesion were associated with lower overall (low-ranking B=-0.111, p=0.001; middle-ranking B=-0.057, p=0.026) and social (low-ranking B=-0.093, p<0.001; middle-ranking B=-0.073, p<0.001) loneliness scores. Among those with high ranking, higher levels of neighborhood social cohesion were associated with lower overall (B=-0.099, p=0.041) and emotional (B=-0.056, p=0.017) loneliness scores, but the associations became insignificant when controlling for maximum lifetime income.

CONCLUSIONS AND IMPLICATIONS

Neighborhood social cohesion may operate differently in different social ranking groups. Interventions to alleviate feelings of loneliness should be subjective social status specific.

Period-Prevalence and Risk Factors for Delirium in a Tertiary Referral ICU: A prospective cohort study

BACKGROUND

Delirium is common in intensive care and leads to increases in morbidity, mortality, Intensive Care Unit (ICU) length of stay, and hospital length of stay. Certain risk factors predict the appearance of delirium.

STUDY OBJECTIVES

To determine the rates of delirium, the rate of risk factors, and their relationship to the occurrence of delirium in an adult ICU.

METHODS

Single-centre, prospective, observational study. Demographic and treatment data were collected. The Confusion Assessment Method for ICU (CAM-ICU) was performed twice daily to assess for delirium continuously during a 3-week period. Statistical analysis was used to determine the relationship between risk factors and the occurrence of delirium.

RESULTS

86 patients were screened, 44 patients were included, and 260 patient-days were analyzed. The incidence of delirium was 42.9%, the prevalence of delirium in ICU was 50%. Urinary catheters and use of opioids were the most common factors with a positive association for occurrence of delirium. Exposure to daylight and sleeping for more than 4 hours at night were the factors most commonly associated with a lack of delirium.

CONCLUSION

The rates of delirium in ICU were high and risk factors occurred frequently. Addressing modifiable risk factors, including the promotion of adequate sleep, could improve outcomes.

IL7R regulates fetal tissue resident macrophage development by facilitating cell survival

Tissue-resident macrophages (TRMs) play critical roles in tissue homeostasis and disease. Many populations of TRMs derive from fetal progenitors and independently self-maintain across the lifespan through in situ proliferation. Previously, we have identified the interleukin-7 receptor (IL7R) as a novel regulator of TRM development. We have shown that antibody blockade of the IL7R during gestation impaired liver, lung, and epidermal TRM cellularity at birth. Here we show that in vivo fetal rIL-7 stimulation of the IL7R increased neonatal liver and lung TRM. In order to determine how IL7R signaling regulates fetal macrophage development, apoptosis was measured after late gestation IL7R blockade. Apoptosis in the macrophages and monocytes of the liver and lung was dramatically increased after IL7R blockade, suggesting that increases in neonatal cellularity after rIL-7 treatment may be due to increased survival signaling in these tissues. Our previous analysis also revealed dynamic regulation of IL7R mRNA surface protein expression as fetal monocytes differentiate into CD64+ macrophages during fetal development. We performed intracellular staining for IL7Ra protein to determine that monocytes contain intracellular IL7R protein that is not expressed on the surface until differentiation, suggesting that regulation of IL7R expression occurs at the level of surface expression. These data reveal dynamic regulation of IL7Ra expression in TRMs and TRM precursors during late gestation and provide evidence that IL-7/IL7R signaling regulates fetal TRM development by facilitating cell survival. Ongoing work addresses downstream signaling and other developmental processes regulated by IL7R signaling during fetal TRM development.

A252 FUNCTIONAL ANALYSIS OF GENETIC AETIOLOGIES IN A DOWNSTREAM OF TYROSINE KINASE (DOK) PROTEIN IN THE PATHOGENESIS OF PEDIATRIC INFLAMMATORY BOWEL DISEASE (IBD)

Background

IBD is a form of chronic inflammatory disorder of the gastrointestinal tract that arises due to genetic, environmental, immunological and microbial factors. The precise pathological mechanisms remain elusive. It is thought that the onset of pediatric IBD can largely be attributed to genetics. Muise lab, at SickKids, regularly screens children at the SickKids IBD clinic and through an international consortium to find possible genetic links to the disease. We report a patient at SickKids with biallelic mutations in DOK4 who has severe Crohn’s Disease along with other inflammatory conditions. Downstream of kinase (DOK) proteins are a family of adaptor molecules that serve as scaffolding proteins important in regulating cell signaling, especially in T cells. DOK4 has been shown to have negative regulatory effects on T cell activation but is also expressed across various other tissues where its function is yet to be determined. We predict that these mutations are causing immune cell dysregulation, which may be contributing to the patients IBD.

Aims

Through this study, we aim to enhance our understanding of the pathobiological mechanism of novel mutations in DOK4.

Methods

We have established T cell lines, expressing wild type and mutated DOK4, which will be used to perform functional tests, such as localization analysis through immunofluorescence and cytokine profiling, to check for T cell function. We have patient derived organoids, which will be used to assess changes in gut morphology using imaging techniques. We will also generate mutant zebrafish model that will be used to determine the susceptibility to colitis related to this mutation, disease progression and gut peristalsis using live imaging technology.

Results

Preliminary data shows variation in expression of the protein within patient derived peripheral blood mononuclear cells (PBMCs) compared to a healthy donor.

Conclusions

With this study, we hope to identify new therapeutic targets for patients with DOK4 mutations.

Funding Agencies

CIHRThe Leona M. and Harry B. Helmsley Charitable Trust

IL7R regulates fetal tissue resident macrophage development

Tissue-resident macrophages (TRMs) play critical roles in tissue homeostasis and disease. Many populations of TRMs derive from fetal progenitors and independently self-maintain across the lifespan through in situ proliferation. Here, we have identified the interleukin-7 receptor (IL7R) as a novel regulator of TRM development. Using an IL7R-Cre lineage tracing model, we observed that adult TRMs in the brain, epidermis, liver, and lung were highly labeled by IL7R-cre, in the absence of IL7Ra mRNA or protein expression. To gain insight into developmental expression of IL7Ra, we profiled surface expression, mRNA expression, and IL7R-cre driven labeling across fetal development. Erythromyeloid progenitors, putative TRM precursors, were barely labeled by IL7Ra-cre, and IL7R deletion did not affect YS hematopoiesis. In contrast, we observed IL7Ra mRNA expression in fetal monocytes, and robust IL7Ra surface expression on developing TRMs during late gestation. Sorted Ly6chi fetal liver monocytes cultured ex vivo with M-CSF differentiated into macrophages expressing IL7R, suggesting a precursor-product relationship. Blockade of the IL7R with a monoclonal antibody during gestation impaired liver, lung, and epidermal TRM cellularity at birth, with a concomitant increase in cellularity of liver monocytes, suggesting that IL7Ra regulates TRM differentiation from fetal monocytes during fetal development. These data reveal dynamic regulation of IL7Ra expression in TRMs and TRM precursors during late gestation, and provide evidence that IL7R signaling regulates fetal TRM development. Ongoing work addresses downstream signaling and the specific developmental processes regulated by IL7R signaling during fetal TRM development.

IL7R regulates fetal tissue resident macrophage development

Tissue-resident macrophages play critical roles in tissue homeostasis and disease. Many populations of tissue-resident macrophages derive from fetal progenitors and self-maintain across the lifespan through in situ proliferation, independent of bone marrow hematopoiesis. However, the developmental mechanisms that specify fetal-derived tissue-resident macrophages are poorly understood. Here, we have identified a novel cytokine regulating tissue-resident macrophage development using an IL7Ra-cre lineage tracing model. Adult tissue resident macrophages in the brain, skin, liver, and lung were extensively labeled by IL7ra-cre, in the absence of IL7ra message or protein expression. To gain insight into developmental expression of IL7ra, we profiled IL7Ra surface expression, mRNA expression, and IL7ra-cre-driven labeling across fetal myeloid development. We observed rapid upregulation of IL7ra surface expression during a limited window of tissue macrophage establishment, and dynamic regulation of IL7ra message and protein levels in monocyte precursors, suggesting that IL7ra regulated the transition from fetal liver monocytes into tissue macrophages. Blockade of the IL7R using a monoclonal antibody decreased cellularity of liver, lung and skin tissue resident macrophages at birth, and increased cellularity of fetal liver monocytes. These data suggest that late in gestation, IL7Ra is upregulated as fetal monocytes exit the fetal liver and differentiate into macrophages, and provides evidence that IL-7R signaling regulates fetal tissue-resident macrophage development. Ongoing work addresses the function of IL-7 signaling in myeloid development, and the function of IL-7R marked macrophages in adult immunity.

Towards Equity in Health: Researchers Take Stock

For the 2016 end-of-the-year editorial, the PLOS Medicine editors asked 7 global health leaders to discuss developments relevant to the equitable provision of medical care to all populations. The result is a collection of expert views on ethical trial design, research during outbreaks, high-burden infectious diseases, diversity in research and protection of migrants.

Comparison of Sagittal FSE T2, STIR, and T1-Weighted Phase-Sensitive Inversion Recovery in the Detection of Spinal Cord Lesions in MS at 3T

BACKGROUND AND PURPOSE

Determining the diagnostic accuracy of different MR sequences is essential to design MR imaging protocols. The purpose of the study was to compare 3T sagittal FSE T2, STIR, and T1-weighted phase-sensitive inversion recovery in the detection of spinal cord lesions in patients with suspected or definite MS.

MATERIALS AND METHODS

We performed a retrospective analysis of 38 patients with suspected or definite MS. Involvement of the cervical and thoracic cord segments was recorded on sagittal FSE T2, STIR, and T1-weighted phase-sensitive inversion recovery sequences independently by 2 readers. A consensus criterion standard read was performed with all sequences available. Sensitivity, specificity, and interobserver agreement were calculated for each sequence.

RESULTS

In the cervical cord, the sensitivity of T1-weighted phase-sensitive inversion recovery (96.2%) and STIR (89.6%) was significantly higher (P < .05) than that of FSE T2 (50.9%), but no significant difference was found between T1-weighted phase-sensitive inversion recovery and STIR. In the thoracic cord, sensitivity values were 93.8% for STIR, 71.9% for FSE T2, and 50.8% for T1-weighted phase-sensitive inversion recovery. Significant differences were found for all comparisons (P < .05). No differences were detected in specificity. Poor image quality and lower sensitivity of thoracic T1-weighted phase-sensitive inversion recovery compared with the other 2 sequences were associated with a thicker back fat pad.

CONCLUSIONS

The use of an additional sagittal sequence other than FSE T2 significantly increases the detection of cervical and thoracic spinal cord lesions in patients with MS at 3T. In the cervical segment, both STIR and T1-weighted phase-sensitive inversion recovery offer high sensitivity and specificity, whereas in the thoracic spine, STIR performs better than T1-weighted phase-sensitive inversion recovery, particularly in patients with a thick dorsal fat pad.

Lung ventilation volumetry with same-breath acquisition of hyperpolarized gas and proton MRI

The purpose of this work was to assess the reproducibility of percentage of ventilated lung volume (PV) measured from hyperpolarized (HP) (3)He and (1)H anatomical images acquired in the same breath-hold when compared with PV measured from (3)He and (1)H images from separate breath-holds. Volumetric (3)He ventilation and (1)H anatomical images of the same resolution were acquired during the same breath-hold. To assess reproducibility, this procedure was performed twice with a short gap between acquisitions. In addition, (1)H images were also acquired in a separate breath for comparison. PV ((3)He ventilated volume divided by (1)H total lung volume) was calculated using the single-breath-hold images (PV(single)) and the separate-breath-hold images (PV(separate)). Short-term reproducibility of PV measurement was assessed for both single- and separate-breath acquisitions. Dice similarity coefficients (DSCs) were calculated to quantify spatial overlap between (3)He and (1)H segmentations for the single- and separate-breath-hold acquisitions. The efficacy of using the separate-breath method combined with image registration was also assessed. The mean magnitude difference between the two sets of PV values (±standard deviation) was 1.49 ± 1.32% for PV(single) and 4.19 ± 4.10% for PV(separate), with a significant difference (p < 0.01). The mean magnitude difference between the two PV values for the registered separate-breath technique (PV(sep-registered)) was 2.27 ± 2.23%. Bland-Altman analysis showed that PV measured with single-breath acquisitions was more repeatable than PV measured with separate-breath acquisitions, regardless of image registration. DSC values were significantly greater (p < 0.01) for single-breath acquisition than for separate-breath acquisition. Acquisition of HP gas ventilation and (1)H anatomical images in a single breath-hold provides a more reproducible means of percentage lung ventilation volume measurement than the previously used separate-breath-hold scan approach, and reduces errors.

Anti-acrolein treatment improves behavioral outcome and alleviates myelin damage in experimental autoimmune encephalomyelitis mouse

Oxidative stress is considered a major contributor in the pathology of multiple sclerosis (MS). Acrolein, a highly reactive aldehyde byproduct of lipid peroxidation, is thought to perpetuate oxidative stress. In this study, we aimed to determine the role of acrolein in an animal model of MS, experimental autoimmune encephalomyelitis (EAE) mice. We have demonstrated a significant elevation of acrolein protein adduct levels in EAE mouse spinal cord. Hydralazine, a known acrolein scavenger, significantly improved behavioral outcomes and lessened myelin damage in spinal cord. We postulate that acrolein is an important pathological factor and likely a novel therapeutic target in MS.

High rate of increased carotid intima-media thickness and atherosclerotic plaques in Chinese asymptomatic subjects with central obesity

Both central obesity and increased carotid intima-media thickness (IMT) are markers of atherosclerosis and associated with cardiovascular diseases (CVD). Information of IMT in Chinese subjects with central obesity is limited. This study was performed to assess the rate of atherosclerosis and abnormal IMT in asymptomatic Chinese subjects with central obesity, and to investigate the association between IMT values and CVD risk factors including hypertension, hyperglycaemia and dyslipidaemia. We studied 122 centrally obese adults who had good past health. IMT measurements on carotid arteries were performed and fasting blood taken for plasma glucose and lipid profiles. Abnormal IMT was defined as > 0.9 mm. Atherosclerosis was defined as the presence of one or more visible plague. Of the 122 subjects, the mean (±SD) age was 59.4 ± 5.8 years (median [range]: 59.0 [45-75] years). The median IMT value was 0.70 mm (range: 0.53-1.19 mm) [men vs. women: 0.74 mm vs. 0.66 mm, P-value: < 0.001]. IMT values and the rate of atherosclerosis increased with age and the number of CVD risk factors (P-value for trend: < 0.05). Using binary logistic regression to predict the presence of atherosclerosis with the presence of abnormal IMT, age, gender, and other CVD risk factors as independent variables, age (OR [95% CI] = 1.13 [1.03, 1.23], P = 0.009) and abnormal IMT (OR [95% CI] = 4.05 [1.09, 15.03], P = 0.037) were independently associated with atherosclerosis. In conclusion, among Hong Kong Chinese asymptomatic subjects with central obesity, there was a high rate of CVD risk factors. We found that 19% of these subjects had carotid atherosclerotic plaques and 10% of them had abnormal IMT (>0.9 mm). Carotid IMT study may serve as an appropriate screening tool to diagnose atherosclerosis in the centrally obese middle-aged population.

Carotid atherosclerotic calcification does not result in high signal intensity in MR imaging of intraplaque hemorrhage

BACKGROUND AND PURPOSE

Calcium can potentially shorten T1, generating high signal intensity in GREs. Because IPH appears as high signal intensity in MRIPH and the surface effects of calcium can potentially shorten T1 of surrounding water protons, the purpose of this study was to evaluate whether the high signal intensity seen on MRIPH could be attributed solely to IPH and not calcification.

MATERIALS AND METHODS

Eleven patients undergoing carotid endarterectomy were imaged by using MRIPH. Calcification was assessed by scanning respective endarterectomy specimens with a tabletop MicroCT. MRIPH/MicroCT correlation used an 8-segment template. Two readers evaluated images from both modalities. Agreement between MRIPH/MicroCT was measured by calculating Cohen κ.

RESULTS

High signal intensity was seen in 58.8% and 68.9% (readers 1 and 2, respectively) of MRIPH segments, whereas calcification was seen in 44.7% and 32.1% (readers 1 and 2, respectively) of MicroCT segments. High signal intensity seen by MRIPH showed very good but inverse agreement to calcification (κ = -0.90; P < .0001, 95% CI, -0.93 to -0.86, reader 1; and κ = -0.74; P < .0001; 95% CI, -0.81 to -0.69, reader 2). Most interesting, high signal intensity demonstrated excellent agreement with lack of calcification on MicroCT (κ = 0.92; P < .0001; 95% CI, 0.89-0.94, reader 1; and κ = 0.97; P < .0001; 95% CI, 0.96-0.99, reader 2). In a very small number of segments, high signal intensity was seen in MRIPH, and calcification was seen on MicroCT; however, these represented a very small proportion of segments with high signal intensity (5.9% and 1.6%, readers 1 and 2, respectively).

CONCLUSIONS

High signal intensity, therefore, reliably identified IPH, known to describe complicated plaque, rather than calcification, which is increasingly recognized as identifying more stable vascular disease.