Neural-specific alterations in glycosphingolipid biosynthesis and cell signaling associated with two human ganglioside GM3 synthase deficiency variants.

GM3 Synthase Deficiency (GM3SD) is a neurodevelopmental disorder resulting from pathogenic variants in the ST3GAL5 gene, which encodes GM3 synthase, a glycosphingolipid (GSL)-specific sialyltransferase. This enzyme adds a sialic acid to the terminal galactose of lactosylceramide (LacCer) to produce the monosialylated ganglioside GM3. In turn, GM3 is extended by other glycosyltransferases to generate nearly all the complex gangliosides enriched in neural tissue. Pathogenic mechanisms underlying the neural phenotypes associated with GM3SD are unknown. To explore how loss of GM3 impacts neural-specific glycolipid glycosylation and cell signaling, GM3SD patient fibroblasts bearing one of two different ST3GAL5 variants were reprogrammed to induced pluripotent stem cells (iPSCs) and then differentiated to neural crest cells (NCCs). GM3 and GM3-derived gangliosides were undetectable in cells carrying either variant, while LacCer precursor levels were elevated compared to wildtype (WT). NCCs of both variants synthesized elevated levels of neutral lacto- and globo-series, as well as minor alternatively sialylated GSLs compared to WT. Ceramide profiles were also shifted in GM3SD variant cells. Altered GSL profiles in GM3SD cells were accompanied by dynamic changes in the cell surface proteome, protein O-GlcNAcylation, and receptor tyrosine kinase abundance. GM3SD cells also exhibited increased apoptosis and sensitivity to erlotinib-induced inhibition of epidermal growth factor receptor signaling. Pharmacologic inhibition of O-GlcNAcase rescued baseline and erlotinib-induced apoptosis. Collectively, these findings indicate aberrant cell signaling during differentiation of GM3SD iPSCs and also underscore the challenge of distinguishing between variant effect and genetic background effect on specific phenotypic consequences.

A mutation in SLC37A4 causes a dominantly inherited congenital disorder of glycosylation characterized by liver dysfunction.

SLC37A4 encodes an endoplasmic reticulum (ER)-localized multitransmembrane protein required for transporting glucose-6-phosphate (Glc-6P) into the ER. Once transported into the ER, Glc-6P is subsequently hydrolyzed by tissue-specific phosphatases to glucose and inorganic phosphate during times of glucose depletion. Pathogenic variants in SLC37A4 cause an established recessive disorder known as glycogen storage disorder 1b characterized by liver and kidney dysfunction with neutropenia. We report seven individuals who presented with liver dysfunction multifactorial coagulation deficiency and cardiac issues and were heterozygous for the same variant, c.1267C>T (p.Arg423∗), in SLC37A4; the affected individuals were from four unrelated families. Serum samples from affected individuals showed profound accumulation of both high mannose and hybrid type N-glycans, while N-glycans in fibroblasts and undifferentiated iPSC were normal. Due to the liver-specific nature of this disorder, we generated a CRISPR base-edited hepatoma cell line harboring the c.1267C>T (p.Arg423∗) variant. These cells replicated the secreted abnormalities seen in serum N-glycosylation, and a portion of the mutant protein appears to relocate to a distinct, non-Golgi compartment, possibly ER exit sites. These cells also show a gene dosage-dependent alteration in the Golgi morphology and reduced intraluminal pH that may account for the altered glycosylation. In summary, we identify a recurrent mutation in SLC37A4 that causes a dominantly inherited congenital disorder of glycosylation characterized by coagulopathy and liver dysfunction with abnormal serum N-glycans.

Work outcomes in public safety personnel after potentially traumatic events: A systematic review.

BACKGROUND: It is well documented that public safety personnel are exposed to potentially traumatic events (PTEs) at elevated frequency and demonstrate higher prevalence of trauma-related symptoms compared to the general population. Lesser studied to date are the organizational consequences of workplace PTE exposure and associated mental health outcomes such as acute/posttraumatic stress disorder (ASD/PTSD), depression, and anxiety. METHODS: The present review synthesizes international literature on work outcomes in public safety personnel (PSP) to explore whether and how PTE and trauma-related symptoms relate to workplace outcomes. A total of N = 55 eligible articles examining PTE or trauma-related symptoms in relation to work outcomes were systematically reviewed using best-evidence narrative synthesis. RESULTS: Three primary work outcomes emerged across the literature: absenteeism, productivity/performance, and costs to organization. Across n = 21 studies of absenteeism, there was strong evidence that PTE or trauma-related symptoms are associated with increased sickness absence. N = 27 studies on productivity/performance demonstrated overall strong evidence of negative impacts in the workplace. N = 7 studies on cost to organizations demonstrated weak evidence that PTE exposure or trauma-related mental health outcomes are associated with increased cost to organization. CONCLUSIONS: Based on available evidence, the experience of workplace PTE or trauma-related symptoms is associated with negative impact on PSP occupational functioning, though important potential confounds (e.g., organizational strain and individual risk factors) remain to be more extensively investigated.

Pertactin contributes to shedding and transmission of Bordetella bronchiseptica.

Whooping cough is resurging in the United States despite high vaccine coverage. The rapid rise of Bordetella pertussis isolates lacking pertactin (PRN), a key vaccine antigen, has led to concerns about vaccine-driven evolution. Previous studies showed that pertactin can mediate binding to mammalian cells in vitro and act as an immunomodulatory factor in resisting neutrophil-mediated clearance. To further investigate the role of PRN in vivo, we examined the functions of pertactin in the context of a more naturally low dose inoculation experimental system using C3H/HeJ mice that is more sensitive to effects on colonization, growth and spread within the respiratory tract, as well as an experimental approach to measure shedding and transmission between hosts. A B. bronchiseptica pertactin deletion mutant was found to behave similarly to its wild-type (WT) parental strain in colonization of the nasal cavity, trachea, and lungs of mice. However, the pertactin-deficient strain was shed from the nares of mice in much lower numbers, resulting in a significantly lower rate of transmission between hosts. Histological examination of respiratory epithelia revealed that pertactin-deficient bacteria induced substantially less inflammation and mucus accumulation than the WT strain and in vitro assays verified the effect of PRN on the induction of TNF-α by murine macrophages. Interestingly, only WT B. bronchiseptica could be recovered from the spleen of infected mice and were further observed to be intracellular among isolated splenocytes, indicating that pertactin contributes to systemic dissemination involving intracellular survival. These results suggest that pertactin can mediate interactions with immune cells and augments inflammation that contributes to bacterial shedding and transmission between hosts. Understanding the relative contributions of various factors to inflammation, mucus production, shedding and transmission will guide novel strategies to interfere with the reemergence of pertussis.

Methodological correlates of variability in the prevalence of posttraumatic stress disorder in high-risk occupational groups: A systematic review and meta-regression.

BACKGROUND: Although numerous studies have reported on PTSD prevalence in high-risk occupational samples, previous meta-analytic work has been severely limited by the extreme variability in prevalence outcomes. METHODS: The present systematic review and meta-regression examined methodological sources of variability in PTSD outcomes across the literature on high-risk personnel with a specific focus on measurement tool selection. RESULTS: The pooled global prevalence of PTSD in high-risk personnel was 12.1% [6.5%, 23.5%], and was similar to estimates obtained in other meta-analytic work. However, meta-regression revealed that PTSD prevalence differed significantly as a function of measurement tool selection, study inclusion criteria related to previous traumatic exposure, sample size, and study quality. PTSD prevalence estimates also differed significantly by occupational group and over time, as has also been reported in previous work, though exploratory examination of trends in measurement selection across these factors suggests that measurement strategy may partially explain some of these previously reported differences. CONCLUSIONS: Our results highlight a pressing need to better understand the role of measurement strategies and other methodological choices in characterizing variable prevalence outcomes. Understanding the role of methodological variance will be critical for work attempting to reliably characterize prevalence as well as risk and protective factors for PTSD.

PREVALENCE AND PREDICTORS OF POSTTRAUMATIC STRESS DISORDER, DEPRESSION, AND ANXIETY IN PERSONNEL WORKING IN EMERGENCY DEPARTMENT SETTINGS: A SYSTEMATIC REVIEW.

BACKGROUND: Professionals working in the emergency department (ED) are regularly exposed to traumatic events. Rates of posttraumatic mental health conditions vary widely in the literature and there is no agreement that rates in ED staff are elevated relative to other populations. OBJECTIVE: We conducted a systematic review of international literature reporting prevalence of posttraumatic stress disorder (PTSD), depression, and anxiety in ED personnel to determine whether prevalence is elevated compared to the general community, and to evaluate convergent evidence across the literature for predictive factors. To our knowledge, there is no comprehensive review on this topic in the literature at this time. METHODS: Seven databases were searched for studies reporting rates of PTSD, depression, and anxiety in ED personnel. Two independent researchers screened studies and assessed quality using Munn's Prevalence Critical Appraisal Instrument. Best-evidence synthesis determined whether conditions demonstrated elevated prevalence compared to the general population of Canada, a conservative benchmark. RESULTS: Twenty-four studies from 12 countries and a combined sample size of 4768 were included. PTSD rates ranged from 0% to 23.6% (mean 10.47%), depression ranged from 0.7% to 77.1% (mean 24.8%), and anxiety rates ranged from 2.4% to 14.6% (mean 9.29%). Each condition was elevated compared to the general population. Sociodemographic variables were not consistent predictors. Elevated PTSD seemed most strongly related to workplace exposure and maladaptive coping. CONCLUSIONS: ED professionals have an elevated risk of experiencing PTSD, depression, and anxiety. Identification of organizational and workplace predictors are needed to inform interventions that will reduce risk and provide optimal treatment and management of PTSD, depression, and anxiety in ED settings.

A model of chronic, transmissible Otitis Media in mice.

Infection and inflammation of the middle ears that characterizes acute and chronic otitis media (OM), is a major reason for doctor visits and antibiotic prescription, particularly among children. Nasopharyngeal pathogens that are commonly associated with OM in humans do not naturally colonize the middle ears of rodents, and experimental models in most cases involve directly injecting large numbers of human pathogens into the middle ear bullae of rodents, where they induce a short-lived acute inflammation but fail to persist. Here we report that Bordetella pseudohinzii, a respiratory pathogen of mice, naturally, efficiently and rapidly ascends the eustachian tubes to colonize the middle ears, causing acute and chronic histopathological changes with progressive decrease in hearing acuity that closely mimics otitis media in humans. Laboratory mice experimentally inoculated intranasally with very low numbers of bacteria consistently have their middle ears colonized and subsequently transmit the bacterium to cage mates. Taking advantage of the specifically engineered and well characterized immune deficiencies available in mice we conducted experiments to uncover different roles of T and B cells in controlling bacterial numbers in the middle ear during chronic OM. The iconic mouse model provides significant advantages for elucidating aspects of host-pathogen interactions in otitis media that are currently not possible using other animal models. This natural model of otitis media permits the study of transmission between hosts, efficient early colonization of the respiratory tract, ascension of the eustachian tube, as well as colonization, pathogenesis and persistence in the middle ear. It also allows the combination of the powerful tools of mouse molecular immunology and bacterial genetics to determine the mechanistic basis for these important processes.

Correction: A model of chronic, transmissible Otitis Media in mice.

[This corrects the article DOI: 10.1371/journal.ppat.1007696.].

The prevalence of PTSD, major depression and anxiety symptoms among high-risk public transportation workers.

OBJECTIVE: Public transportation workers are exposed to higher levels of stress related to accidents, injuries, and person-under-train events when compared to other workers. This systematic review integrates the existing literature on mental health among high-risk public transportation workers to estimate the prevalence of post-traumatic stress disorder (PTSD), major depressive and anxiety symptoms following critical incidents while on duty. METHODS: This systematic review is part of a larger systematic review which examines mental health and work outcomes of individuals working in professions at high risk of critical incident exposure, i.e., high-risk professions. Articles were included if they measured the prevalence of PTSD, Major Depressive Disorder (MDD) and Anxiety Disorder (AD) in a transportation population following exposure to a major incident, for example, a person-under-a-train. RESULTS: Among the ten articles, all reported prevalence of PTSD which ranged from 0.73 to 29.9%. Four articles reported prevalence of depression among transportation workers exposed to a critical incident and prevalence outcomes ranged from 0.05 to 16.3%. Only two reported prevalence of anxiety from 1.3 to 13.9%. CONCLUSIONS: This literature reports that transportation workers are prone to involvement in traumatic accidents leading to higher rates of PTSD compared to the general population. Strategies to reduce transportation accidents and to provide transportation workers follow-up mental health support is needed for this vulnerable population.

Bordetella bronchiseptica exploits the complex life cycle of Dictyostelium discoideum as an amplifying transmission vector.

Multiple lines of evidence suggest that Bordetella species have a significant life stage outside of the mammalian respiratory tract that has yet to be defined. The Bordetella virulence gene (BvgAS) two-component system, a paradigm for a global virulence regulon, controls the expression of many "virulence factors" expressed in the Bvg positive (Bvg+) phase that are necessary for successful respiratory tract infection. A similarly large set of highly conserved genes are expressed under Bvg negative (Bvg-) phase growth conditions; however, these appear to be primarily expressed outside of the host and are thus hypothesized to be important in an undefined extrahost reservoir. Here, we show that Bvg- phase genes are involved in the ability of Bordetella bronchiseptica to grow and disseminate via the complex life cycle of the amoeba Dictyostelium discoideum. Unlike bacteria that serve as an amoeba food source, B. bronchiseptica evades amoeba predation, survives within the amoeba for extended periods of time, incorporates itself into the amoeba sori, and disseminates along with the amoeba. Remarkably, B. bronchiseptica continues to be transferred with the amoeba for months, through multiple life cycles of amoebae grown on the lawns of other bacteria, thus demonstrating a stable relationship that allows B. bronchiseptica to expand and disperse geographically via the D. discoideum life cycle. Furthermore, B. bronchiseptica within the sori can efficiently infect mice, indicating that amoebae may represent an environmental vector within which pathogenic bordetellae expand and disseminate to encounter new mammalian hosts. These data identify amoebae as potential environmental reservoirs as well as amplifying and disseminating vectors for B. bronchiseptica and reveal an important role for the Bvg- phase in these interactions.

Evidence of learning and memory in the juvenile dwarf cuttlefish Sepia bandensis.

Measuring behavior in the form of numerical data is difficult, especially for studies involving complex actions. DanioVision is a closed-chamber system that utilizes subject tracking to comprehensively record behavior, while also mitigating the influence of environmental conditions. We used DanioVision to record activity of juvenile dwarf cuttlefish (Sepia bandensis) during the inaccessible prey (IP) procedure, a memory experiment in which cuttlefish learn to inhibit capture attempts towards inaccessible prey. By quantifying total movement and orientation of the body, we found that cuttlefish show memory by selectively inhibiting tentacle strikes without reducing total movement, or orientation towards the prey. We show that DanioVision can be used to assess multiple components of dynamic responses that are not measurable by direct observation alone and provide new evidence that strike inhibition is the product of learning, and not motor fatigue.

Systematic review of posttraumatic stress disorder in police officers following routine work-related critical incident exposure.

BACKGROUND: The prevalence of PTSD in police officers has been the subject of a large and highly variable empirical literature. The present systematic review evaluates the extant literature on PTSD in police officers using an international dataset. METHODS: We employed best-evidence narrative synthesis to evaluate whether PTSD prevalence in police is elevated in comparison to the general population of Canada (8%), which itself has a higher lifetime PTSD prevalence than many other regions and thus serves as a conservative standard of comparison. RESULTS: PTSD prevalence in police varied considerably across studies from 0% - 44% (M = 14.87%, Median = 9.2%). Despite this variability, strong evidence exists to suggest PTSD prevalence is elevated in police officers. Examination of possible sources of variability in prevalence outcomes highlighted substantial variability in outcomes due to the selection of measurement tool for assessing PTSD (e.g., DSM vs. IES). Examination of commonly-assessed predictive factors for PTSD risk across the literature showed that individual-difference factors (e.g., age, years of service) bear weak-to-nonexistent relationships with PTSD risk, while incident-specific factors (e.g., severity of exposure) are more strongly and consistently associated with PTSD prevalence. Organizational factors (e.g., low support from supervisor) are at present understudied but important possible contributors to PTSD risk. CONCLUSIONS: PTSD prevalence is elevated in police officers and appears most strongly related to workplace exposure. Measurement variability remains a critical source of inconsistencies across the literature with drastic implications for accurate detection of officers in need of mental health intervention.

Parental perspective: Factors that played a role in facilitating or impeding the parents' understanding of their child's developmental diagnostic assessment.

BACKGROUND: Full parental understanding of a child's diagnosis of a developmental disability is critical to be able to ensure the best health outcome for their child. Yet factors that parents perceived as influencing their comprehension during the final diagnostic meeting have not been well identified. METHOD: This study used a qualitative interpretive description approach. Seventeen parents were interviewed who received a child's developmental diagnosis from one of the clinical multidisciplinary teams located in northern British Columbia. The interviews focused on the factors that played a role in facilitating or impeding the parents' understanding of their child's diagnosis, and on the identification of factors that influenced the way in which the child's clinical recommendations were pursued. RESULTS: Two overarching themes with nine subthemes emerged from parents' reported experiences of receiving their child's developmental diagnosis. The themes and subthemes included (a) clinical encounter (including the subthemes structural considerations, professional diversity and new insights, questions regarding the assessment process, and validation) and (b) manner of the delivery of the diagnosis (emotional impact, impact on parenting practices, professionalism, professional language, and quantity of information). CONCLUSIONS: Parents' accounts established and clarified the positive and negative parental determinants that aided or challenged their ability to understand their child's developmental diagnosis during the final clinical interaction with the multidisciplinary team.

Development of macrolide resistance in Bordetella bronchiseptica is associated with the loss of virulence.

Background: Why resistance to specific antibiotics emerges and spreads rapidly in some bacteria confronting these drugs but not others remains a mystery. Resistance to erythromycin in the respiratory pathogens Staphylococcus aureus and Streptococcus pneumoniae emerged rapidly and increased problematically. However, resistance is uncommon amongst the classic Bordetella species despite infections being treated with this macrolide for decades. Objectives: We examined whether the apparent progenitor of the classic Bordetella spp., Bordetella bronchiseptica, is able to rapidly generate de novo resistance to antibiotics and, if so, why such resistance might not persist and propagate. Methods: Independent strains of B. bronchiseptica resistant to erythromycin were generated in vitro by successively passaging them in increasing subinhibitory concentrations of this macrolide. Resistant mutants obtained were evaluated for their capacity to infect mice, and for other virulence properties including adherence, cytotoxicity and induction of cytokines. Results: B. bronchiseptica rapidly developed stable and persistent antibiotic resistance de novo. Unlike the previously reported trade-off in fitness, multiple independent resistant mutants were not defective in their rates of growth in vitro but were consistently defective in colonizing mice and lost a variety of virulence phenotypes. These changes rendered them avirulent but phenotypically similar to the previously described growth phase associated with the ability to survive in soil, water and/or other extra-mammalian environments. Conclusions: These observations raise the possibility that antibiotic resistance in some organisms results in trade-offs that are not quantifiable in routine measures of general fitness such as growth in vitro, but are pronounced in various aspects of infection in the natural host.

Mental Disorders in Firefighters Following Large-Scale Disaster.

Firefighting service is known to involve high rates of exposure to potentially traumatic situations, and research on mental health in firefighting populations is of critical importance in understanding the impact of occupational exposure. To date, the literature concerning prevalence of trauma-related mental disorders such as posttraumatic stress disorder (PTSD) has not distinguished between symptomology associated routine duty-related exposure and exposure to large-scale disaster. The present systematic review synthesizes a heterogeneous cross-national literature on large-scale disaster exposure in firefighters and provides support for the hypothesis that the prevalence of PTSD, major depressive disorder, and anxiety disorders are elevated in firefighters compared with rates observed in the general population. In addition, we conducted narrative synthesis concerning several commonly assessed predictive factors for disorder and found that sociodemographic factors appear to bear a weak relationship to mental disorder, while incident-related factors, such as severity and duration of disaster exposure, bear a stronger and more consistent relationship to the development of PTSD and depression in cross-national samples. Future work should expand on these preliminary findings to better understand the impact of disaster exposure in firefighting personnel.

A biopsychosocial perspective on the management of work-related musculoskeletal disorders.

This article provides an overview of current literature about workplace-related musculoskeletal disorders from a biopsychosocial perspective. The authors conclude that disability management and early intervention efforts can only be meaningful within the context of targeted interventions, including mechanisms for psychosocial screening. In addition, they suggest that return to work should be considered an integral, rather than superficial, contribution to the rehabilitative process.

Work disability prevention in rural healthcare workers.

INTRODUCTION: Approximately 20% of healthcare workers in high-income countries such as Australia, Canada and the USA work in rural areas. Healthcare workers are known to be vulnerable to occupational injury and poor work disability outcomes; given their rural-urban distribution, it is possible to compare work disability prevention in rural and urban areas. However, little attention has been paid to work disability prevention issues specific to rural workers, including rural healthcare workers. A comprehensive review of the literature was conducted to identify rural-urban differences in work disability outcomes (defined as the incidence of occupational injury and the duration of associated work absence), as well as risk factors for poor work disability outcomes in rural healthcare workers. METHODS: The databases MEDLINE, CINAHL, and EMBASE were searched, as were relevant research centers and government agencies, to identify all quantitative and qualitative English-language studies published between 1 January 2000 and 6 October 2009 that discussed occupational injury, work absence duration, work disability management, or risk factors for poor work disability outcomes, for rural workers specifically, or in comparison with urban workers. To ensure inclusion of studies of healthcare workers as a distinct group among other sector-specific groups, a broad search for literature related to all industrial sectors was conducted. RESULTS: Of 860 references identified, 5 discussed work disability outcomes and 25 discussed known risk factors. Known risk factors were defined as factors firmly established to be associated with poor work disability outcomes in the general worker population based on systematic reviews, well-established conceptual models of work disability prevention, and public health literature. Although somewhat conflicting, the evidence suggests that rural healthcare workers experience higher rates of occupational injury compared with urban healthcare workers, within occupational categories. Rural workers also appear to be more vulnerable to prolonged work absence although the data are limited. No studies directly compared risk factors for work disability prevention outcomes between rural and urban healthcare workers. However, potential risk factors were identified at the level of the environment, worker, job, organization, worker compensation system and healthcare access. Important methodological limitations were noted, including unclear definitions of rurality, inadequate methods of urban-rural comparisons such as comparing samples from different countries, and a paucity of studies applying longitudinal or multivariate designs. CONCLUSIONS: There is a notable lack of evidence about work disability prevention issues for healthcare workers in rural areas. Available evidence supports the hypothesis that rural healthcare workers are vulnerable to occupational injury, and suggests they are vulnerable to prolonged work absence. They may be particularly vulnerable to poor work disability prevention outcomes due to complex patient needs in the context of risk factors such as heavy workloads, long hours, heavy on-call demands, high stress levels, limited support and workplace violence. Additional vulnerability may occur because their work conditions are managed in distant urban administrative centers, and due to barriers in their own healthcare access. Although rural healthcare workers seem generally at greater risk of injury, one study suggests that urban emergency medical service workers experience a high vulnerability to injury that may outweigh the effects of rurality. Additional research is needed to document rural-urban disparities in work disability outcomes and to identify associated sources and risk factors. Other issues to address are access to and quality of healthcare for rural healthcare workers, streamlining the compensation system, the unique needs of Aboriginal healthcare workers, and the management of prolonged work absence. Finally, occupational injury and work absence duration programs should be tailored to meet the needs of rural workers.

Sleep Duration and Obesity in Children and Adolescents.

Increased rates of obesity internationally have drawn significant attention. In particular, researchers and practitioners are seeking new information about risk factors for obesity that could be areas for preventive interventions. Given that obesity rates in children and adolescents are increasing worldwide, particular attention to child and adolescent obesity is needed. A large, and growing, body of research indicates that inadequate sleep duration is linked to obesity. The current article reviews the extant literature concerning sleep duration and obesity in children and adolescents by reviewing current theories of obesity as well as available literature specifically evaluating the relationship of obesity and sleep in children and adolescents, including epidemiologic, experimental and intervention research. Overall, our literature review concludes that the relationship between shortened sleep and increased risk for obesity has research support internationally, including in the few Canadian articles available that are discussed in our review.