Dosimetric validation of SmART-RAD Monte Carlo modelling for x-ray cabinet radiobiology irradiators

Objective. Accuracy and reproducibility in the measurement of radiation dose and associated reporting are critically important for the validity of basic and preclinical radiobiological studies performed with kilovolt x-ray radiation cabinets. This is essential to enable results of radiobiological studies to be repeated, as well as enable valid comparisons between laboratories. In addition, the commonly used single point dose value hides the 3D dose heterogeneity across the irradiated sample. This is particularly true for preclinical rodent models, and is generally difficult to measure directly. Radiation transport simulations integrated in an easy to use application could help researchers improve quality of dosimetry and reporting.Approach. This paper describes the use and dosimetric validation of a newly-developed Monte Carlo (MC) tool, SmART-RAD, to simulate the x-ray field in a range of standard commercial x-ray cabinet irradiators used for preclinical irradiations. Comparisons are made between simulated and experimentally determined dose distributions for a range of configurations to assess the potential use of this tool in determining dose distributions through samples, based on more readily available air-kerma calibration point measurements.Main results. Simulations gave very good dosimetric agreement with measured depth dose distributions in phantoms containing both water and bone equivalent materials. Good spatial and dosimetric agreement between simulated and measured dose distributions was obtained when using beam-shaping shielding.Significance. The MC simulations provided by SmART-RAD provide a useful tool to go from a limited number of dosimetry measurements to detailed 3D dose distributions through a non-homogeneous irradiated sample. This is particularly important when trying to determine the dose distribution in more complex geometries. The use of such a tool can improve reproducibility and dosimetry reporting in preclinical radiobiological research.

Endothelial cell death after ionizing radiation does not impair vascular structure in mouse tumor models

The effect of radiation therapy on tumor vasculature has long been a subject of debate. Increased oxygenation and perfusion have been documented during radiation therapy. Conversely, apoptosis of endothelial cells in irradiated tumors has been proposed as a major contributor to tumor control. To examine these contradictions, we use multiphoton microscopy in two murine tumor models: MC38, a highly vascularized, and B16F10, a moderately vascularized model, grown in transgenic mice with tdTomato-labeled endothelium before and after a single (15 Gy) or fractionated (5 × 3 Gy) dose of radiation. Unexpectedly, even these high doses lead to little structural change of the perfused vasculature. Conversely, non-perfused vessels and blind ends are substantially impaired after radiation accompanied by apoptosis and reduced proliferation of their endothelium. RNAseq analysis of tumor endothelial cells confirms the modification of gene expression in apoptotic and cell cycle regulation pathways after irradiation. Therefore, we conclude that apoptosis of tumor endothelial cells after radiation does not impair vascular structure.

Associations between courses of posttraumatic stress disorder and physical health conditions among Canadian military personnel

BACKGROUND

Posttraumatic stress disorder (PTSD) and physical health conditions commonly co-occur and are both prevalent among military personnel. This study examined how courses of PTSD (no PTSD, remitted, new onset, persistent/recurrent) are associated with physical health conditions, among a population-based sample of Canadian military personnel.

METHOD

We analyzed data from the 2002 Canadian Community Health Survey-Mental Health and Well-being-Canadian Forces supplement (CCHS-CF) and the 2018 Canadian Armed Forces Members and Veterans Mental Health Follow-Up Survey (CAFVMHS; N = 2941). Multivariable logistic regressions examined associations between PTSD courses (reference = no PTSD) and physical health conditions.

RESULTS

In general, physical health conditions were more prevalent among symptomatic PTSD courses compared to no PTSD. After adjustment, new onset PTSD was associated with increased odds of all physical health conditions with the exception of ulcers and cancer (AOR range: 1.41-2.31) and remitted PTSD was associated with increased odds of diabetes (AOR = 2.31).

CONCLUSION

Results suggest that new onset PTSD may be most strongly associated with physical health conditions. Findings may inform targeted screening and intervention methods among military personnel with PTSD and physical health conditions.

Lifetime Prevalence and Comorbidity of Mental Disorders in the Two-wave 2002-2018 Canadian Armed Forces Members and Veterans Mental Health Follow-up Survey (CAFVMHS): Prévalence et Comorbidité de Durée de vie Des Troubles Mentaux Dans l'Enquête de Suivi Sur la Santé Mentale Auprès des Membres des Forces Armées Canadiennes et Des ex-Militaires (ESSMFACM) en Deux Cycles de 2002 à 2018

OBJECTIVE

The current study used the Canadian Armed Forces Members and Veterans Mental Health Follow-up Survey (CAFVMHS) to (1) examine the incidence and prevalence of mental disorders and (2) estimate the comorbidity of mental disorders over the follow-up period.

METHOD

The CAFVMHS (2018) is a longitudinal study with two time points of assessment. The sample is comprised of 2,941 Canadian Forces members and veterans who participated in the 2002 Canadian Community Health Survey: Canadian Forces Supplement. The World Health Organization Composite International Diagnostic Interview (WHO-CIDI) was utilized to diagnose Diagnostic and Statistical Manual-IV post-traumatic stress disorder (PTSD), major depressive episode (MDE), generalized anxiety disorder, social anxiety disorder (SAD), and alcohol abuse and dependence. Self-report health professional diagnoses were assessed for attention deficit hyperactivity disorder (ADHD), mania, obsessive compulsive disorder (OCD), and personality disorder. We established weighted prevalence of mental disorders and examined the association between mental disorders using logistic regression.

RESULTS

In 2018, lifetime prevalence of any WHO-CIDI-based or self-reported mental disorder was 58.1%. Lifetime prevalence of any mood or anxiety disorder or PTSD was 54.0% in 2018. MDE (39.9%), SAD (25.7%), and PTSD (21.4%) were the most common mental disorders. There was a substantial increase in new onset or recurrence/persistence of mental disorders between the two measurement points (16-year assessment gap); 2002-2018 period prevalences were 43.5% for mood and anxiety disorder and 16.8% for alcohol abuse or dependence. The prevalence of self-reported ADHD, OCD, any personality disorder, and mania were 3.3%, 3.0%, 0.8%, and 0.8%, respectively. Comorbidity between mental disorders increased over the follow-up.

CONCLUSIONS

This study demonstrates a high burden of mental disorders among a large Canadian military and veteran cohort. These findings underscore the importance of prevention and intervention strategies to reduce the burden of mental disorders and alcohol use disorders in these populations.

The impact of different Hormonal Growth Promotants (HGP) on desmin degradation and collagen content of various muscles from pasture and feedlot finished steer carcasses

The impacts of several hormonal growth promotants (HGP) on Warner-Bratzler Shear Force (WBSF), desmin degradation ratio (DDR) and collagen content (COLL) were assessed. Treatments within feedlot and pasture finished steer carcasses (n = 60, n = 40, respectively) were control (CON-100-F and CON-400-P), oestradiol HGPs (OES-100-F and OES-400-P) and trenbolone acetate/oestradiol HGPs (TBA+OES-100-F only). The longissimus lumborum (LL), gluteus medius (GM), infraspinatus (IS), semitendinosus (ST,) and the LL and biceps femoris (BF) were collected from feedlot and pasture finished steers, respectively. All muscles were aged between 3 and 35 days. The LL from TBA+OES-100-F carcasses had increased WBSF and decreased DDR, which varied in magnitude with ageing (P < 0.05). The GM from OES-100-F steers also had lower DDR (P < 0.05). The feedlot HGP treatments had no impact on the WBSF of the IS, ST or GM and no impact on COLL in the LL. The OES-400-P had no impact on WBSF, DDRor COLL for both muscles (P > 0.05).

Chronic pain experience and health inequities during the COVID-19 pandemic in Canada: qualitative findings from the chronic pain & COVID-19 pan-Canadian study

BACKGROUND

Chronic pain affects about 20 % of the Canadian population and can lead to physical, psychological and social vulnerabilities. However, this condition remains poorly recognized and undertreated. During 2020, as the COVID-19 pandemic disrupted daily living and health care systems, the situation of people with chronic pain has drawn little public attention.

METHODS

This qualitative study was part of a pan-Canadian mixed-methods project and aimed to understand the experiences and challenges of people living with chronic pain during the COVID-19 pandemic in Canada. Between May and August 2020, we conducted in-depth semi-structured interviews with 22 individuals living with chronic pain across the country. We used reflexive thematic analysis to interpret data.

RESULTS

Our findings underscored four dimensions of the chronic pain experience during the pandemic: (1) Reinforced vulnerability due to uncertainties regarding pain and its management; (2) Social network as a determinant of pain and psychological condition; (3) Increasing systemic inequities intermingling with the chronic pain experience; (4) More viable living conditions due to confinement measures. Though several participants reported improvements in their quality of life and reduced social pressure in the context of stay-at-home orders, participants from socio-economically deprived groups and minorities reported more challenges in accessing pain relief, health care services, and psychosocial support.

CONCLUSIONS

The COVID-19 pandemic has revealed and intensified pre-existing disparities and challenges among people living with chronic pain in terms of material resources, psychosocial condition, social support, and access to care. In post-pandemic times, it will be essential to address flaws in health and welfare policies to foster equity and social inclusiveness of people with chronic pain.

Does a single adjustment in the meat standards Australia beef grading model cater for different hormonal growth promotant formulations?

This paper investigated whether a single Hormonal Growth Promotant (HGP) adjustment in the Meat Standards Australia (MSA) beef grading model adequately predicted consumer eating quality of beef from cattle treated with different HGP formulations. This paper used consumer sensory data from two experiments. In experiment one, a total of 300 steers were allocated to three treatments; control (CON-100-F), 100 day oestradiol only HGP (OES-100-F), or a combination of trenbolone acetate and oestradiol HGP (TBA+OES-100-F) and finished in a feedlot for 73 days. In experiment two, a total of 200 steers were allocated either control or 400 day oestradiol only HGP treatments and finished on pasture for 389 days. Steers were slaughtered by finishing regime and carcass traits recorded. The anterior and posterior portions of the m. longissimus lumborum (LL-A and LL-P, respectively) and m. gluteus medius (GM) were collected and aged for five or 35 days. Grilled meat samples were scored for tenderness, juiciness, liking of flavour and overall acceptability using untrained consumers. Sensory scores were weighted by 0.3. 0.1, 0.3 and 0.3, respectively and summed to calculate a meat quality (MQ4) score. Residual MQ4 scores were calculated (observed MQ4 minus the predicted MQ4 score). The MSA model accounts for varied impacts of different HGPs on eating quality through a single HGP adjustment, and indirect impacts on carcass traits. For the majority of the HGP treatment samples, the residual MQ4 scores were not different to zero (5/18), or were positive i.e. the MSA model under-predicted these samples (11/18). Under-prediction was predominately for 35 day aged (7/9) and GM HGP treatment samples (6/6) and was considered low, with the majority less than ±5 MQ4 units. Under-prediction could be considered as advantageous through providing an additional safeguard to protect the interests of the consumers, rather than if the model had over-predicted and resulted in a more negative eating quality experience than expected. Some over-prediction was observed in the CON-100-F and TBA+OES-100-F treatment samples, which may be due to factors such as genetic variation and/or production environment. Minimal bias was observed when residual MQ4 was regressed against predicted MQ4 for the range of feeding regimes, muscles, ageing periods and treatment groups. This study showed that a single HGP adjustment in the MSA beef grading model, combined with the indirect effects of the different HGP formulations on carcass traits, provided a reasonable prediction of meat eating quality for different HGP formulations.

Ongoing repair of migration-coupled DNA damage allows planarian adult stem cells to reach wound sites

Mechanical stress during cell migration may be a previously unappreciated source of genome instability, but the extent to which this happens in any animal in vivo remains unknown. We consider an in vivo system where the adult stem cells of planarian flatworms are required to migrate to a distal wound site. We observe a relationship between adult stem cell migration and ongoing DNA damage and repair during tissue regeneration. Migrating planarian stem cells undergo changes in nuclear shape and exhibit increased levels of DNA damage. Increased DNA damage levels reduce once stem cells reach the wound site. Stem cells in which DNA damage is induced prior to wounding take longer to initiate migration and migrating stem cell populations are more sensitive to further DNA damage than stationary stem cells. RNAi-mediated knockdown of DNA repair pathway components blocks normal stem cell migration, confirming that active DNA repair pathways are required to allow successful migration to a distal wound site. Together these findings provide evidence that levels of migration-coupled-DNA-damage are significant in adult stem cells and that ongoing migration requires DNA repair mechanisms. Our findings reveal that migration of normal stem cells in vivo represents an unappreciated source of damage, which could be a significant source of mutations in animals during development or during long-term tissue homeostasis.

Cluster analysis of Canadian Armed Forces veterans living with chronic pain: Life After Service Studies 2016

Objective: This study explored the heterogeneity of Canadian Armed Forces veterans living with chronic pain to inform service needs planning and research using cluster analysis. Design: We used a national cross-sectional Statistics Canada population survey. Participants: Participants included 2754 Canadian Armed Forces (CAF) Regular Force veterans released from service between 1998 and 2015 and surveyed in 2016. Methods: We used cluster analysis of veterans with chronic pain based on pain severity, mental health, and activity limitation characteristics. We compared clusters for sociodemographic, health, and service utilization characteristics. Results: Of 2754 veterans, 1126 (41%) reported chronic pain. Veterans in cluster I (47%) rarely had severe pain (2%) or severe mental health problems (8%), and none had severe activity limitations. Veterans in cluster II (26%) more often than veterans in cluster I but less often than veterans in cluster III endorsed severe pain (27%) and severe mental health problems (22%) and were most likely to report severe activity limitation (91%). Veterans in cluster III (27%) were most likely to report severe pain (36%) and severe mental health problems (96%), and a majority reported severe activity limitations (72%). There was evidence of considerable heterogeneity among individuals in terms of socioeconomic characteristics, pain characteristics, mental and physical health status, activity limitations, social integration, and service utilization indicators. Conclusions: About half of Canadian veterans living with chronic pain infrequently endorse severe pain or serious mental health issues without severe activity limitations. The other half had more complex characteristics. The heterogeneity of CAF veterans with chronic pain emphasizes the need for support systems that can address variability of needs.

Olaparib increases the therapeutic index of hemithoracic irradiation compared with hemithoracic irradiation alone in a mouse lung cancer model

Background

The radiosensitising effect of the poly(ADP-ribose) polymerase inhibitor olaparib on tumours has been reported. However, its effect on normal tissues in combination with radiation has not been well studied. Herein, we investigated the therapeutic index of olaparib combined with hemithoracic radiation in a urethane-induced mouse lung cancer model.

Methods

To assess tolerability, A/J mice were treated with olaparib plus whole thorax radiation (13 Gy), body weight changes were monitored and normal tissue effects were assessed by histology. In anti-tumour (intervention) studies, A/J mice were injected with urethane to induce lung tumours, and were then treated with olaparib alone, left thorax radiation alone or the combination of olaparib plus left thorax radiation at 8 weeks (early intervention) or 18 weeks (late intervention) after urethane injection. Anti-tumour efficacy and normal tissue effects were assessed by visual inspection, magnetic resonance imaging and histology.

Results

Enhanced body weight loss and oesophageal toxicity were observed when olaparib was combined with whole thorax but not hemithorax radiation. In both the early and late intervention studies, olaparib increased the anti-tumour effects of hemithoracic irradiation without increasing lung toxicity.

Conclusions

The addition of olaparib increased the therapeutic index of hemithoracic radiation in a mouse model of lung cancer.

A cross-sectional study of pain status and psychological distress among individuals living with chronic pain: the Chronic Pain & COVID-19 Pan-Canadian Study

BACKGROUND

The COVID-19 pandemic has had a disproportionate impact on vulnerable populations, including individuals with chronic pain. We examined associations between geographical variations in COVID-19 infection rates, stress and pain severity, and investigated factors associated with changes in pain status and psychological distress among individuals living with chronic pain during the pandemic.

METHODS

This investigation is part of a larger initiative, the Chronic Pain & COVID-19 Pan-Canadian Study, which adopted a cross-sectional observational design. A total of 3159 individuals living with chronic pain completed a quantitative survey between 16 April and 31 May 2020.

RESULTS

Two-thirds (68.1%) of participants were between 40 and 69 years old, and 83.5% were women. Two-thirds (68.9%) of individuals reported worsened pain since pandemic onset. Higher levels of perceived pandemic-related risks (adjusted odds ratio: 1.27; 95% confidence interval: 1.03-1.56) and stress (1.21; 1.05-1.41), changes in pharmacological (3.17; 2.49-4.05) and physical/psychological (2.04; 1.62-2.58) pain treatments and being employed at the beginning of the pandemic (1.42; 1.09-1.86) were associated with increased likelihood of reporting worsened pain. Job loss (34.9% of individuals were employed pre-pandemic) was associated with lower likelihood (0.67; 0.48-0.94) of reporting worsened pain. Almost half (43.2%) of individuals reported moderate/severe levels of psychological distress. Negative emotions toward the pandemic (2.14; 1.78-2.57) and overall stress (1.43; 1.36-1.50) were associated with moderate/severe psychological distress.

CONCLUSIONS

Study results identified psychosocial factors to consider in addition to biomedical factors in monitoring patients' status and facilitating treatment access for chronic pain patients during a pandemic.

Impact of the COVID-19 pandemic on the pharmacological, physical, and psychological treatments of pain: findings from the Chronic Pain & COVID-19 Pan-Canadian Study

INTRODUCTION

Multimodal treatment is recognized as the optimal paradigm for the management of chronic pain (CP). Careful balance between pharmacological and physical/psychological approaches is thus desirable but can be easily disrupted.

OBJECTIVES

This study aimed at exploring the impact of the COVID-19 pandemic on pharmacological and physical/psychological treatments of CP.

METHODS

A Pan-Canadian cross-sectional web-based study was conducted between April 16th and May 31st 2020 among adults living with CP when the country was in the ascending slope of the first COVID-19 pandemic wave.

RESULTS

A total of 2864 participants shared their treatment experience (mean age: 49.7 years and women: 83.5%). Among medication users (n = 2533), 38.3% reported changes in their pharmacological pain treatment. The main reasons were as follows: (1) changes in pain symptoms, (2) lack of access to prescribers/cancellation of medical appointments, and (3) increased medication intake in compensation for stopping physical/psychological treatments because of the pandemic. Among participants who used physical/psychological pain management approaches before the pandemic (n = 2467), 68.3% had to modify their treatments or self-management strategies. Common reasons were lack of access to clinics/exercise facilities and the need to compensate for having to stop another type of physical/psychological treatment because of the pandemic-related public health safety measures.

CONCLUSIONS

Our study underlines the negative impact of the COVID-19 pandemic on access to pain relief, which is considered a fundamental human right. Results will help to justify resource allocation and inform the development of interventions to be better prepared for waves to come and future health crises.

Prediction of consumer palatability in beef using visual marbling scores and chemical intramuscular fat percentage

With development of objective technologies that can predict chemical intramuscular fat percentage (IMF%), there is a need to understand the relationships between existing marbling traits, IMF% and eating quality. This study utilised historical carcass data (n = 9641 observations) from the Meat Standards Australia (MSA) industry research dataset and included MSA grading data, chemical IMF% data and weighted composite eating quality scores (MQ4). Several analyses were performed to assess the prediction of MQ4 by MSA marbling, M. longissimus thoracis et lumborum (striploin) IMF% and cut specific IMF%. Results demonstrated that there was similar precision between chemical IMF% (R² = 0.32, RSE = 11.8) and MSA marbling (R² = 0.28, RSE = 11.9) in the prediction of grilled 14 day aged striploin MQ4, with similar results across other cut by cook by days aged combinations. These results support the development of objective technologies that predict chemical IMF% in parallel with MSA marbling for carcass grading and the prediction of eating quality.

Out of the shadows: Chronic pain in Canadian Armed Forces veterans - Proceedings of a workshop at the 2019 Forum of the Canadian Institute for Military and Veteran Health Research

This commentary summarizes proceedings of a workshop on chronic pain in military personnel and veterans (released personnel) at the Annual Forum of the Canadian Institute for Military and Veteran Health Research in Gatineau and Ottawa on October 22, 2019. The extent and impact of chronic pain among Canadian Armed Forces (CAF) veterans and their families is significant and has been underappreciated, largely due to limited disclosure by serving and veteran military personnel, stemming from a fear of stigmatization. Living with pain is seen as a fact of life in military cultures, something to be endured and not discussed. Though progress is being made in reducing the stigma of mental illness, the discourse on chronic pain remains censored. This workshop's goal was to bring the discussion of chronic pain out of the shadows in the search for ways to help veterans and active service personnel living with chronic pain. Many points of view were brought forward at this first national Canadian multidisciplinary gathering of researchers, veterans with lived experience, clinicians, and policymakers. A CAF member described his lived experience with constant chronic pain. Clinicians described aspects of chronic pain in military personnel and veterans whom they treat in their clinics. Dr. Ramesh Zacharias described the new Chronic Pain Center of Excellence for Canadian Veterans that will be established with funding from Veterans Affairs Canada. Dr. Norman Buckley highlighted collaboration with the existing Chronic Pain Network funded by the Canadian Institute for Health Research. Audience members identified a diverse variety of issues.

Density compensated diodes for small field dosimetry: comprehensive testing and implications for design

PURPOSE

In small megavoltage photon fields, the accuracies of an unmodified PTW 60017-type diode dosimeter and six diodes modified by adding airgaps of thickness 0.6-1.6 mm and diameter 3.6 mm have been comprehensively characterized experimentally and computationally. The optimally thick airgap for density compensation was determined, and detectors were micro-CT imaged to investigate differences between experimentally measured radiation responses and those predicted computationally.

METHODS

Detectors were tested on- and off-axis, at 5 and 15 cm depths in 6 and 15 MV fields ≥ 0.5 × 0.5 cm². Computational studies were carried out using the EGSnrc/BEAMnrc Monte Carlo radiation transport code. Experimentally, radiation was delivered using a Varian TrueBeam linac and doses absorbed by water were measured using Gafchromic EBT3 film and ionization chambers, and compared with diode readings. Detector response was characterized via the [Formula: see text] formalism, choosing a 4 × 4 cm² reference field.

RESULTS

For the unmodified 60017 diode, the maximum error in small field doses obtained from diode readings uncorrected by [Formula: see text] factors was determined as 11.9% computationally at +0.25 mm off-axis and 5 cm depth in a 15 MV 0.5 × 0.5 cm² field, and 11.7% experimentally at -0.30 mm off-axis and 5 cm depth in the same field. A detector modified to include a 1.6 mm thick airgap performed best, with maximum computationally and experimentally determined errors of 2.2% and 4.1%. The 1.6 mm airgap deepened the modified dosimeter's effective point of measurement by 0.5 mm. For some detectors significant differences existed between responses in small fields determined computationally and experimentally, micro-CT imaging indicating that these differences were due to within-tolerance variations in the thickness of an epoxy resin layer.

CONCLUSIONS

The dosimetric performance of a 60017 diode detector was comprehensively improved throughout 6 and 15 MV small photon fields via density compensation. For this approach to work well with good detector-to-detector reproducibility, tolerances on dense component dimensions should be reduced to limit associated variations of response in small fields, or these components should be modified to have more water-like densities.

Group identity, diffi cult adjustment to civilian life, and suicidal ideation in Canadian Armed Forces Veterans: Life After Service Studies 2016

Introduction: Suicide risk is higher in Canadian Armed Forces (CAF) Veterans than the Canadian general population (CGP). Suicidality is understood to be caused by incompletely clarified, complex interacting combinations of multiple factors. One of the precipitating factors for suicide is thought to be the social identity challenges known to occur in major life transitions. Methods: The 2016 Life After Service Studies survey representatively sampled Regular Force Veterans stratified by two release groups: earlier in 1998 to August 2012 ( n = 1,575) and more recently in September 2012 to 2015 ( n = 1,180). The linked dataset included socioeconomic and military characteristics and well-being indicators in multiple domains. Weak group identity was indicated by weak sense of local community belonging and/or not feeling part of a group with shared attitudes and beliefs. Associations were evaluated with multiple logistic regression. Results: Suicidal ideation, weak community belonging, and perceived difficult adjustment to civilian life were more prevalent in Veterans soon after release (September 2012 to 2015) than in Veterans released earlier (1998 to August 2012). Suicidal ideation and weak community belonging were more prevalent in the Veterans than in the CGP. In the more recently released Veterans, weak group identity was endorsed by the majority with suicidal ideation (93.3%). In adjusted regression models, mental health problems had the strongest association with suicidal ideation (adjusted odds ratio [AOR] = 13.4–79.3); however, weak group identity was moderately strongly associated with both difficult adjustment (AOR = 2.4–4.1) and particularly suicidal ideation (AOR = 3.8–9.0), independently of mental health problems. Discussion: Weak group identity was associated with difficult adjustment to civilian life and suicidal ideation in CAF Regular Force Veterans within 3.6 years after military release. These findings indicate the importance in suicide prevention of attending to social identity during transition to post-military life.

Life course well-being framework for suicide prevention in Canadian Armed Forces Veterans

Introduction: The risks of suicidality (suicidal ideation or behaviour) are higher in Canadian Armed Forces (CAF) Veterans (former members) than in the Canadian general population (CGP). Suicide prevention is everyone’s responsibility, but it can be difficult for many to see how they can help. This article proposes an evidence-based theoretical framework for discussing suicide prevention. The framework informed the 2017 joint CAF – Veterans Affairs Canada (VAC) suicide prevention strategy. Methods: Evidence for the framework was derived from participation in expert panels conducted by the CAF in 2009 and 2016, a review of findings from epidemiological studies of suicidality in CAF Veterans released since 1976, suicide prevention literature reviews conducted at VAC since 2009, and published theories of suicide. Results: Common to all suicide theories is the understanding that suicide causation is multifactorial, complex, and varies individually such that factors interact rather than lie along linear causal chains. Discussion: The proposed framework has three core concepts: a composite well-being framework, the life course view, and opportunities for prevention along the suicide pathway from ideation to behaviour. Evidence indicates that Veterans are influenced onto, along, and off the pathway by variable combinations of mental illness, stressful well-being problems and life events, individual factors including suicidal diathesis vulnerability, barriers to well-being supports, acquired lethal capability, imitation, impulsivity, and access to lethal means. The proposed framework can inform discussions about both whole-community participation in prevention, intervention and postvention activities at the individual and population levels, and the development of hypotheses for the increased risk of suicidality in CAF Veterans.

Radiosensitivity of colorectal cancer to 90Y and the radiobiological implications for radioembolisation therapy

Approximately 50% of all colorectal cancer (CRC) patients will develop metastasis to the liver. ⁹⁰Y selective internal radiation therapy (SIRT) is an established treatment for metastatic CRC. There is still a fundamental lack of understanding regarding the radiobiology underlying the dose response. This study was designed to determine the radiosensitivity of two CRC cell lines (DLD-1 and HT-29) to ⁹⁰Y β⁻ radiation exposure, and thus the relative effectiveness of ⁹⁰Y SIRT in relation to external beam radiotherapy (EBRT).

A ⁹⁰Y-source dish was sandwiched between culture dishes to irradiate DLD-1 or HT-29 cells for a period of 6 d. Cell survival was determined by clonogenic assay. Dose absorbed per ⁹⁰Y disintegration was calculated using the PENELOPE Monte Carlo code. PENELOPE simulations were benchmarked against relative dose measurements using EBT3 GAFchromic^™ film. Statistical regression based on the linear-quadratic model was used to determine the radiosensitivity parameters and using R. These results were compared to radiosensitivity parameters determined for 6 MV clinical x-rays and ¹³⁷Cs γ-ray exposure. Equivalent dose of EBRT in 2 Gy () and 10 Gy () fractions were derived for ⁹⁰Y dose.

HT-29 cells were more radioresistant than DLD-1 for all treatment modalities. Radiosensitivity parameters determined for 6 MV x-rays and ¹³⁷Cs γ-ray were equivalent for both cell lines. The ratio for ⁹⁰Y β⁻-particle exposure was over an order of magnitude higher than the other two modalities due to protraction of dose delivery. Consequently, an ⁹⁰Y SIRT absorbed dose of 60 Gy equates to an of 28.7 and 54.5 Gy and an of 17.6 and 19.3 Gy for DLD-1 and HT-29 cell lines, respectively.

We derived radiosensitivity parameters for two CRC cell lines exposed to ⁹⁰Y β⁻-particles, 6 MV x-rays, and ¹³⁷Cs γ-ray irradiation. These radiobiological parameters are critical to understanding the dose response of CRC lesions and ultimately informs the efficacy of ⁹⁰Y SIRT relative to other radiation therapy modalities.

TRACKING DOWN ALPHA-PARTICLES: THE DESIGN, CHARACTERISATION AND TESTING OF A SHALLOW-ANGLED ALPHA-PARTICLE IRRADIATOR

Human exposure to α-particles from radon and other radionuclides is associated with carcinogenesis, but if well controlled and targeted to cancer cells, α-particles may be used in radiotherapy. Thus, it is important to understand the biological effects of α-particles to predict cancer risk and optimise radiotherapy. To enable studies of α-particles in cells, we developed and characterised an α-particle automated irradiation rig that allows exposures at a shallow angle (70° to the normal) of cell monolayers in a 30 mm diameter dish to complement standard perpendicular irradiations. The measured incident energy of the α-particles was 3.3 ± 0.5 MeV (LET in water = 120 keV μm-1), with a maximum incident dose rate of 1.28 ± 0.02 Gy min-1, which for a 5 μm cell monolayer corresponds to a mean dose rate of 1.57 ± 0.02 Gy min-1 and a mean LET in water of 154 keV μm-1. The feasibility of resolving radiation-induced DNA double-strand breaks (DSB) foci along the track of α-particles was demonstrated using immunofluorescent labelling with γH2AX and 53BP1 in normal MRC-5 human lung cells.

Reflections on recovery, rehabilitation and reintegration of injured service members and veterans from a bio-psychosocial-spiritual perspective

Medical interventions regarding trauma resuscitation have increased survivorship to levels not previously attained. Multiple examples from recent conflicts illustrate the potential return to high-level function of severely injured service members following medical and rehabilitative interventions. This review addresses the goals of rehabilitation, distills hard-won lessons of the last decade of military trauma and rehabilitation, and recommends the use of a bio-psychosocial-spiritual approach to care that can be applied at all tiers of the health care system. Questions on enabling participation in meaningful life activities include the following: Why do some patients do well and others do not? What elements contribute to positive outcomes? What factors relate to suboptimal results? Lessons learned revolve around the importance of considering the physical, psychosocial and spiritual aspects of a person’s well-being; empowering patients by fostering self-efficacy; and helping patients find meaning in life events and set high-level goals. A bio-psychosocial-spiritual model from the rehabilitation medicine literature — the Canadian Model of Occupational Performance and Engagement — is proposed as a guide to the provision of person-centred care and the maximization of a person’s functioning posttrauma.

Characterisation of Deubiquitylating Enzymes in the Cellular Response to High-LET Ionizing Radiation and Complex DNA Damage

PURPOSE

Ionizing radiation, particular high-linear energy transfer (LET) radiation, can induce complex DNA damage (CDD) wherein 2 or more DNA lesions are induced in close proximity, which contributes significantly to the cell killing effects. However, knowledge of the enzymes and mechanisms involved in coordinating the recognition and processing of CDD in cellular DNA are currently lacking.

METHODS AND MATERIALS

A small interfering RNA screen of deubiquitylation enzymes was conducted in HeLa cells irradiated with high-LET α-particles or protons, versus low-LET protons and x-rays, and cell survival was monitored by clonogenic assays. Candidates whose depletion led to decreased cell survival specifically in response to high-LET radiation were validated in both HeLa and oropharyngeal squamous cell carcinoma (UMSCC74A) cells, and the association with CDD repair was confirmed using an enzyme modified neutral comet assay.

RESULTS

Depletion of USP6 decreased cell survival specifically after high-LET α-particles and protons, but not low-LET protons or x-rays. USP6 depletion caused cell cycle arrest and a deficiency in CDD repair mediated through instability of poly(ADP-ribose) polymerase-1 (PARP-1) protein. Increased radiosensitivity of cells to high-LET protons as a consequence of defective CDD repair was furthermore mimicked using the PARP inhibitor olaparib, and through PARP-1 small interfering RNA.

CONCLUSIONS

USP6 controls cell survival in response to high-LET radiation by stabilizing PARP-1 protein levels, which is essential for CDD repair. We also describe synergy between CDD induced by high-LET protons and PARP inhibition, or PARP-1 depletion, in effective cancer cell killing.

Treatment of military-related post-traumatic stress disorder: challenges, innovations, and the way forward

Post-traumatic stress disorder (PTSD) is one of the common mental disorders in military and veteran populations. Considerable research and clinical opinion has been focused on understanding the relationship between PTSD and military service and the implications for prevention, treatment, and management. This paper examines factors associated with the development of PTSD in this population, considers issues relating to engagement in treatment, and discusses the empirical support for best practice evidence-based treatment. The paper goes on to explore the challenges in those areas, with particular reference to treatment engagement and barriers to care, as well as treatment non-response. The final section addresses innovative solutions to these challenges through improvements in agreed terminology and definitions, strategies to increase engagement, early identification approaches, understanding predictors of treatment outcome, and innovations in treatment. Treatment innovations include enhancing existing treatments, emerging non-trauma-focused interventions, novel pharmacotherapy, personalized medicine approaches, advancing functional outcomes, family intervention and support, and attention to physical health.

Effects of variations in overall treatment time on the clonogenic survival of V79-4 cells: Implications for radiosurgery

The importance of effects related to the repair of sublethal radiation damage as treatment duration varies, partly a function of dose-rate, is a current controversy in clinical radiosurgery. Cell survival studies have been performed to verify the importance of this effect in relation to established models. Mammalian V79-4 cells were irradiated in vitro with γ-rays, either as an acute exposure in a few minutes, where the effects of sublethal irradiation damage repair over the period of exposure can be ignored, or as protracted exposures delivered over 15-120 min. Protraction was achieved either by introducing a variable time gap between two doses of 7 Gy, or as a continuous exposure at lower dose rates so that a range of doses were delivered in fixed times of 30, 60 or 120 min. For all doses there was a progressive reduction in efficacy with increasing overall treatment time. This was illustrated by the progressive increase in clonogenic cell survival with a resulting right shift of the survival curves. Cell survival curves for irradiations given either as an acute exposure (6.1 Gy/min), over fixed times (30, 60 and 120 min) or for a fixed low dose-rate (0.2 Gy/min) were well fitted by the Linear Quadratic (LQ) model giving an α/β ratio of 4.0 Gy and a single repair half-time of 31.5 min. The present results are consistent with published data with respect to the response of solid tumors and normal tissues, whose response to both continuous and fractionated irradiation is also well described by the LQ model. This suggests the need for dose compensation in radiosurgical treatments, and other forms of radiotherapy, where dose is delivered over a similar range of protracted overall treatment times, perhaps as a prerequisite to full biological effective dose treatment planning.

High-resolution μCT of a mouse embryo using a compact laser-driven X-ray betatron source

In the field of X-ray microcomputed tomography (μCT) there is a growing need to reduce acquisition times at high spatial resolution (approximate micrometers) to facilitate in vivo and high-throughput operations. The state of the art represented by synchrotron light sources is not practical for certain applications, and therefore the development of high-brightness laboratory-scale sources is crucial. We present here imaging of a fixed embryonic mouse sample using a compact laser-plasma-based X-ray light source and compare the results to images obtained using a commercial X-ray μCT scanner. The radiation is generated by the betatron motion of electrons inside a dilute and transient plasma, which circumvents the flux limitations imposed by the solid or liquid anodes used in conventional electron-impact X-ray tubes. This X-ray source is pulsed (duration <30 fs), bright (>1010 photons per pulse), small (diameter <1 μm), and has a critical energy >15 keV. Stable X-ray performance enabled tomographic imaging of equivalent quality to that of the μCT scanner, an important confirmation of the suitability of the laser-driven source for applications. The X-ray flux achievable with this approach scales with the laser repetition rate without compromising the source size, which will allow the recording of high-resolution μCT scans in minutes.

The effect of packaging on consumer eating quality of beef

This experiment examined 3 packaging systems: overwrap packaging using oxygen permeable film (OWP); vacuum skin packaging (VSP) and modified atmosphere packaging (MAP, 80%O₂ and 20%CO₂) on consumer sensory. Three primals from 48 carcasses were aged in vacuum packs for 5, 12 or 40 days. Steaks from longissimus lumborum, gluteus medius and psoas major muscles were packed in OWP, VSP and MAP for 9 days. Untrained consumers scored grilled steaks for tenderness, juiciness, liking of flavour and overall acceptability. Steaks in MAP had 10-12 points lower sensory scores (on a 100 point scale) compared to the OWP, or VSP systems (P < 0.001). The packaging effect was independent of days aging and muscle. It was concluded that high oxygen MAP has the potential to be included as an input variable in the Meat Standards Australia beef grading model. This would be contingent upon research into when the MAP effect occurred and the effect of using different gas mixtures on eating quality.

Do extended transport times and rest periods impact on eating quality of beef carcasses?

The experiment tested the effect of four extended transport treatments on sensory and objective meat quality in beef. A total of 343 steers (88 steers from each of three properties and 79 from a fourth property) were allocated to four treatments including a 12 hour transport time (T12), 24 hour transport time (T24), 24 h as 12 hour transport time, a 12 hour rest, with a further 12 hour transport (T12 ~ T12), 36 hour transport treatment (T36). Within property departure times of treatments were staggered to arrive at the abattoir together. There were no significant transport effects (P > .05) on live animal, carcass traits, consumer sensory scores, and objective meat quality of the longissimus lumborum. There was large between property variation in the proportions of carcasses excluded from grading on the basis of low ribfat, high ultimate pH and dark meat color scores. Variation in these traits was not associated with transport treatments and was likely related to variation in on-farm factors.

Out of the shadows: mental health of Canadian armed forces veterans

In the past 15 years in Canada, as in other nations, the mental health of veterans has emerged as a key concern for both government and the public. As mental health service enhancement unfolded, the need for wider population studies became apparent. This paper describes the renewal of services and key findings from national surveys of serving personnel and veterans.

Complex DNA Damage Induced by High Linear Energy Transfer Alpha-Particles and Protons Triggers a Specific Cellular DNA Damage Response

Purpose

To investigate the precise mechanism of recognition and processing of ionizing radiation (IR)-induced complex DNA damage (CDD), where two or more DNA lesions are in close proximity, in cellular DNA which is packaged with histones to form chromatin.

Methods and Materials

HeLa and oropharyngeal squamous cell carcinoma (UMSCC74A and UMSCC6) cells were irradiated with high linear energy transfer (LET) α-particles or protons, versus low-LET protons and X rays. At various time points after irradiation, site-specific histone post-translational modifications were analyzed by quantitative Western blotting; DNA damage and repair were measured by different versions of the comet assay; and cell survival was determined using clonogenic assays.

Results

Site-specific histone post-translational modifications after low- and high-LET radiation, particularly proton irradiation, were screened, aiming to identify those responsive to CDD. We demonstrate that histone H2B ubiquitylated on lysine 120 (H2B_ub) is specifically induced several hours after irradiation in response to high-LET α-particles and protons but not by low-LET protons or X rays/γ-radiation. This is associated with increased levels of CDD, which contributes to decreased cell survival. We further discovered that modulation of H2B_ub is under the control of two E3 ubiquitin ligases, MSL2 and RNF20/RNF40 complex, whose depletion leads to defective processing and further persistence of CDD, and to additional decreased cell survival after irradiation.

Conclusion

This study demonstrates that the signaling and repair of CDD, particularly induced by high-LET IR is co-ordinated through the specific induction of H2B_ub catalyzed by MSL2 and RNF20/40, a mechanism that contributes significantly to cell survival after irradiation.

The Development of Technology for Effective Respiratory-Gated Irradiation Using an Image-Guided Small Animal Irradiator

The development of image-guided small animal irradiators represents a significant improvement over standard irradiators by enabling preclinical studies to mimic radiotherapy in humans. The ability to deliver tightly collimated targeted beams, in conjunction with gantry or animal couch rotation, has the potential to maximize tumor dose while sparing normal tissues. However, the current commercial platforms do not incorporate respiratory gating, which is required for accurate and precise targeting in organs subject to respiration related motions that may be up to the order of 5 mm in mice. Therefore, a new treatment head assembly for the Xstrahl Small Animal Radiation Research Platform (SARRP) has been designed. This includes a fast X-ray shutter subsystem, a motorized beam hardening filter assembly, an integrated transmission ionization chamber to monitor beam delivery, a kinematically positioned removable beam collimator and a targeting laser exiting the center of the beam collimator. The X-ray shutter not only minimizes timing errors but also allows beam gating during imaging and treatment, with irradiation only taking place during the breathing cycle when tissue movement is minimal. The breathing related movement is monitored by measuring, using a synchronous detector/lock-in amplifier that processes diffuse reflectance light from a modulated light source. After thresholding of the resulting signal, delays are added around the inhalation/exhalation phases, enabling the "no movement" period to be isolated and to open the X-ray shutter. Irradiation can either be performed for a predetermined time of X-ray exposure, or through integration of a current from the transmission monitor ionization chamber (corrected locally for air density variations). The ability to successfully deliver respiratory-gated X-ray irradiations has been demonstrated by comparing movies obtained using planar X-ray imaging with and without respiratory gating, in addition to comparing dose profiles observed from a collimated beam on EBT3 radiochromic film mounted on the animal's chest. Altogether, the development of respiratory-gated irradiation facilitates improved dose delivery during animal movement and constitutes an important new tool for preclinical radiation studies. This approach is particularly well suited for irradiation of orthotopic tumors or other targets within the chest and abdomen where breathing related movement is significant.

Efficacy of radiosensitizing doped titania nanoparticles under hypoxia and preparation of an embolic microparticle

The aim of this study was to develop a manufacturing protocol for large-scale production of doped titania radiosensitizing nanoparticles (NPs) to establish their activity under hypoxia and to produce a multimodal radiosensitizing embolic particle for cancer treatment. We have previously shown that radiosensitizing NPs can be synthesized from titania doped with rare earth elements, especially gadolinium. To translate this technology to the clinic, a crucial step is to find a suitable, scalable, high-throughput method. Herein, we have described the use of flame spray pyrolysis (FSP) to generate NPs from titanium and gadolinium precursors to produce titania NPs doped with 5 at% gadolinium. The NPs were fully characterized, and their capacity to act as radiosensitizers was confirmed by clonogenic assays. The integrity of the NPs in vitro was also ascertained due to the potentially adverse effects of free gadolinium in the body. The activity of the NPs was then studied under hypoxia since this is often a barrier to effective radiotherapy. In vitro radiosensitization experiments were performed with both the hypoxia mimetics deferoxamine and cobalt chloride and also under true hypoxia (oxygen concentration of 0.2%). It was shown that the radiosensitizing NPs were able to cause a significant increase in cell death even after irradiation under hypoxic conditions such as those found in tumors. Subsequently, the synthesized NPs were used to modify polystyrene embolization microparticles. The NPs were sintered to the surface of the microparticles by heating at 230°C for 15 minutes. This resulted in a good coverage of the surface and to generate embolization particles that were shown to be radiosensitizing. Such multimodal particles could therefore result in occlusion of the tumor blood vessels in conjunction with localized reactive oxygen species generation, even under hypoxic conditions such as those found in the center of tumors.

Rho-associated kinase 1 inhibition is synthetically lethal with von Hippel-Lindau deficiency in clear cell renal cell carcinoma

Clear Cell Renal Cell Carcinoma (CC-RCC) is the most lethal of all genitourinary cancers. The functional loss of the von Hippel-Lindau (VHL) gene occurs in 90% of CC-RCC, driving cancer progression. The objective of this study was to identify chemical compounds that are synthetically lethal with VHL deficiency in CC-RCC. An annotated chemical library, the Library of Pharmacologically Active Compounds (LOPAC), was screened in parallel on VHL-deficient RCC4 cells and RCC4VHL cells with re-introduced VHL cDNA. The ROCK inhibitor, Y-27632, was identified and validated for selective targeting of VHL-deficient CC-RCC in multiple genetic backgrounds by clonogenic assays. Downregulation of ROCK1 by siRNA selectively reduced the colony forming ability of VHL-deficient CC-RCC, thus mimicking the effect of Y-27632 treatment, whereas downregulation of ROCK2 had no effect. In addition, two other ROCK inhibitors, RKI 1447 and GSK 429286, selectively targeted VHL-deficient CC-RCC. CC-RCC treatment with ROCK inhibitors is cytotoxic and cytostatic based on BrdU assay, Propidium Iodide (PI) staining, and growth curves; and blocks cell migration based on transwell assay. Importantly, knockdown of Hypoxia Inducible Factor (HIF) β in the VHL-deficient CC-RCC had a protective effect against Y-27632 treatment, mimicking VHL reintroduction. On the other hand, CC-RCCVHL cells were sensitized to Y-27632 treatment in hypoxia (2% O₂). These results suggest that synthetic lethality between ROCK inhibition and VHL deficiency is dependent on HIF activation. Moreover, HIF1α or HIF2α overexpression in CC-RCCVHL cells is sufficient to sensitize them to ROCK inhibition. Finally, Y-27632 treatment inhibited growth of subcutaneous 786-OT1 CC-RCC tumors in mice. Thus, ROCK inhibitors represent potential therapeutics for VHL-deficient CC-RCC.

Organizational and market factors associated with Medicare dependence in inpatient rehabilitation hospitals

Rehabilitation hospitals in the USA have been excluded from the Medicare Prospective Payment System (PPS) system since 1982, and have received cost-based reimbursement. However, the 1997 Balanced Budget Act mandated a PPS for inpatient rehabilitation, to be implemented by the end of 2002. This study assesses rehabilitation hospitals' dependency on Medicare. Findings show that not-for-profit hospitals, facilities with fewer services, facilities with lower staffing levels, and hospitals with lower operating expenses and profits, have a higher proportion of their inpatient revenue coming from Medicare. These facilities may be vulnerable to the new PPS payment system.

Mental health of Canadian Armed Forces Veterans: review of population studies

Introduction. The mental health of Canadian Armed Forces (CAF) populations emerged as an important concern in the wake of difficult CAF deployments in the 1990s. This article is the first comprehensive summary of findings from subsequent surveys of mental health and well-being in CAF Veterans, undertaken to inform mental health service renewals by CAF Health Services and Veterans Affairs Canada (VAC). Methods. Epidemiological findings in journal publications and government reports were summarized from four cross-sectional national surveys: a survey of Veterans participating in VAC programs in 1999 and three surveys of health and well-being representative of whole populations of Veterans in 2003, 2010, and 2013. Results. Although most Veterans had good mental health, many had mental health problems that affected functioning, well-being, and service utilization. Recent Veterans had a higher prevalence of mental health problems than the general Canadian population, earlier-era Veterans, and possibly the serving population. There were associations between mental health conditions and difficult adjustment to civilian life, physical health, and multiple socio-demographic factors. Mental health problems were key drivers of disability. Comparisons with other studies were complicated by methodological, era, and cultural differences. Discussion. The survey findings support ongoing multifactorial approaches to optimizing mental health and well-being in CAF Veterans, including strong military-to-civilian transition support and access to effective mental and physical health services. Studies underway of transitioning members and families in the peri-release period of the military-to-civilian transition and longitudinal studies of mental health in Veterans will address important knowledge gaps.

Multivariate assessment of health-related quality of life in Canadian Armed Forces Veterans after transition to civilian life

Introduction: The goal of this study was to identify factors associated with the SF-12 Physical Component Summary (PCS) and Mental Component Summary (MCS) measures of health-related quality of life (HRQOL) in former Canadian Armed Forces (CAF) Veterans after transition to civilian life. Methods: Data were taken from the 2010 Survey on Transition to Civilian Life, a national computer-assisted telephone survey of CAF Regular Force personnel who released during 1998–2007. Multivariate linear regression models were developed using a variety of socio-economic, military, health, and disability characteristics. Results: Mean age was 46 years (range 20–67 y), and 12% of the participants were women. Higher age was associated with lower PCS but higher MCS scores. High ratings of mastery and high satisfaction with life were strongly associated with higher scores on both the PCS and the MCS. Most chronic physical health conditions were associated with poorer PCS scores, in particular chronic pain, musculoskeletal conditions, cancer, gastrointestinal conditions, hearing problems and, to a lesser degree, chronic mental health conditions. The only chronic condition associated with poorer MCS scores was presence of one or more mental health conditions. Both activity limitation in major life domains and needing assistance with activities of daily living were negatively associated with PCS scores, whereas only the latter was negatively associated with MCS scores. Discussion: The models suggested protective factors and identified characteristics of subgroups vulnerable to poor HRQOL after accounting for confounding. Findings can be used to identify those at high risk who may benefit from targeted interventions and to develop health promotion and prevention strategies for Canadian Armed Forces personnel in transition to civilian life.

Neurocognitive intra-individual variability in mood disorders: effects on attentional response time distributions

BACKGROUND

Attentional impairment is a core cognitive feature of major depressive disorder (MDD) and bipolar disorder (BD). However, little is known of the characteristics of response time (RT) distributions from attentional tasks. This is crucial to furthering our understanding of the profile and extent of cognitive intra-individual variability (IIV) in mood disorders.

METHOD

A computerized sustained attention task was administered to 138 healthy controls and 158 patients with a mood disorder: 86 euthymic BD, 33 depressed BD and 39 medication-free MDD patients. Measures of IIV, including individual standard deviation (iSD) and coefficient of variation (CoV), were derived for each participant. Ex-Gaussian (and Vincentile) analyses were used to characterize the RT distributions into three components: mu and sigma (mean and standard deviation of the Gaussian portion of the distribution) and tau (the 'slow tail' of the distribution).

RESULTS

Compared with healthy controls, iSD was increased significantly in all patient samples. Due to minimal changes in average RT, CoV was only increased significantly in BD depressed patients. Ex-Gaussian modelling indicated a significant increase in tau in euthymic BD [Cohen's d = 0.39, 95% confidence interval (CI) 0.09-0.69, p = 0.011], and both sigma (d = 0.57, 95% CI 0.07-1.05, p = 0.025) and tau (d = 1.14, 95% CI 0.60-1.64, p < 0.0001) in depressed BD. The mu parameter did not differ from controls.

CONCLUSIONS

Increased cognitive variability may be a core feature of mood disorders. This is the first demonstration of differences in attentional RT distribution parameters between MDD and BD, and BD depression and euthymia. These data highlight the utility of applying measures of IIV to characterize neurocognitive variability and the great potential for future application.

A Systems Pharmacology Model of Erythropoiesis in Mice Induced by Small Molecule Inhibitor of Prolyl Hydroxylase Enzymes

Mammalian erythropoiesis is a conserved process tightly controlled by the hypoxia-inducible factor (HIF1) pathway. In this study, a small molecule inhibitor (PHI-1) of prolyl-hydroxylase-2 (PHD2) enzyme involved in regulating HIF1α levels was orally administered to male BALB/c mice at 10 and 30 mg/kg. A systems pharmacology model was developed based on the measured PHI-1 plasma exposures, kidney HIF1α, kidney erythropoietin (EPO) mRNA, plasma EPO, reticulocyte counts, red blood cells, and hemoglobin levels. The model fit resulted in the estimation of drug potency (IC₅₀: 1.7μM), and systems parameters such as EPO mRNA turnover (k_{deg_EPOmRNA}: 0.43 hr^-1) and mean lifespan of reticulocytes (T_r: 81 hours). The model correctly described the observed 30–40-fold increase in kidney HIF1α protein, ∼1,000 fold increase in EPO mRNA and 2–3-fold increase in the reticulocytes at 30 mg/kg. This study presents the first parsimonious systems model of erythropoiesis to quantitatively describe the in vivo effects of PHD2 inhibition.

Glenoid notch MRI findings do not predict normal variants of the anterior and superior labrum

AIM

To determine (1) the relationship of a glenoid notch to the presence of a normal labral variant in the anterior-superior glenoid labrum; (2) the inter- and intra-observer reliability of recognising a glenoid notch; and (3) whether magnetic resonance arthrography (MRA) is more reliable than non-contrast magnetic resonance imaging (MRI) in visualising a glenoid notch.

MATERIALS AND METHODS

From 1995 through 2010, 104 patients underwent MRI or MRA before diagnostic shoulder arthroscopy by the senior author. Five blinded musculoskeletal radiologists independently read the images twice to evaluate for the presence or absence of a glenoid notch. Fifty-nine (57%) patients had normal anterior-superior labral variants. The authors calculated the relationship of the readings to the arthroscopically determined presence or absence of a normal labral variant and the reading's diagnostic performance and rater reliability.

RESULTS

On average, 38% (range 9-65%) of the glenoid scans were read as notched. The sensitivity, specificity, positive predictive value, and negative predictive value of the notch relative to the presence of a normal variant were 43.1%, 71.2%, 70.2%, and 48% versus 44.3%, 77.5%, 79.4%, and 56.1% for MRI and MRA, respectively. The overall average intra-observer κ-values were 0.438 (range 0.203-0.555) and 0.346 (range -0.102 to 0.570) for MRI and MRA, respectively. The average interobserver intra-class correlation coefficient reliability values were 0.730 (range 0.693-0.760) and 0.614 (range 0.566-0.662) for MRI and MRA, respectively.

CONCLUSIONS

A notched glenoid on MRI lacks sufficient diagnostic performance and rater reliability for the clinical detection and prediction of normal anterior-superior labral variants.

Ruralizing the Canadian Triage and Acuity Scale

L’échelle canadienne de triage et de gravité (ÉTG) a été introduite dans les années 90 et est rapidement en voie de devenir la norme canadienne de triage. Mais depuis 1997, moment où l’Institut canadien d’information sur la santé a commencé à promouvoir l’ÉTG, certains médecins de campagne ont manifesté leurs préoccupations, signalant l’existence de d’autres systèmes de triage et mettant en doute l’efficacité de l’ÉTG dans les milieux ruraux.

Les médecins des milieux ruraux soulèvent divers points: une perception de la complexité de l’ÉTG, un délai de réponse apparemment court pour l’évaluation par le médecin (et les ramifications médico-légales de la définition de ces délais), et une validation inadéquate de l’ÉTG dans les milieux ruraux. Le présent article explore l’historique de cette controverse et ébauche des solutions possibles. Les auteurs concluent que l’ÉTG est un outil malléable qui peut être «adapté» aux milieux ruraux et qu’il permettra par la suite d’améliorer les soins aux patients et les conditions de travail des infirmières et des médecins de ces milieux.

Comorbidity and functional correlates of anxiety and physical conditions in Canadian Veterans

Introduction: Little is known about the relationship between anxiety disorders and physical conditions in Canadian Veterans. The purpose of this investigation was to examine the comorbidity of anxiety and physical conditions and their relation to physical and mental health–related quality of life and activity limitations in a nationally representative sample of Canadian Veterans. Methods: Participants were selected from the cross-sectional 2010 Survey on Transition to Civilian Life ( N = 3,154, response rate = 71.0%). The sample consisted of former Canadian Armed Forces Regular Force personnel who were released from 1998 to 2007. Multivariate logistic and linear regression models evaluated associations between several commonly occurring chronic physical conditions and any anxiety disorder and correlates (i.e., quality of life and activity limitations) of comorbidity. Results: Any anxiety disorder was associated with significantly elevated rates of cardiovascular, gastrointestinal, respiratory, and musculoskeletal conditions; diabetes; and chronic pain after controlling for sociodemographics, military characteristics, any mood disorder, and heavy drinking. However, when additionally controlling for number of physical conditions, any anxiety disorder remained significantly associated with gastrointestinal conditions (adjusted odds ratio [AOR] = 1.63, 99% confidence interval [CI] = 1.07–2.50) and chronic pain (AOR = 1.79, 99% CI = 1.15–2.78). Co-occurring anxiety disorders and musculoskeletal conditions were associated with poorer physical health–related quality of life and activity limitations than musculoskeletal conditions alone. Conclusion: Anxiety disorders and physical health problems co-occur at high rates among Canadian Veterans, and this comorbidity is linked to poorer physical health–related quality of life and activity limitations. These findings have implications for supporting at-risk personnel with the transition to civilian life and for informing health promotion and prevention efforts.

Out of the shadows: mental health of Canadian armed forces veterans

In the past 15 years in Canada, as in other nations, the mental health of veterans has emerged as a key concern for both government and the public. As mental health service enhancement unfolded, the need for wider population studies became apparent. This paper describes the renewal of services and key findings from national surveys of serving personnel and veterans.

Disability correlates in Canadian Armed Forces Regular Force Veterans

PURPOSE

This study was undertaken to inform disability mitigation for military veterans by identifying personal, environmental, and health factors associated with activity limitations.

METHOD

A sample of 3154 Canadian Armed Forces Regular Force Veterans who were released during 1998-2007 participated in the 2010 Survey on Transition to Civilian Life. Associations between personal and environmental factors, health conditions and activity limitations were explored using ordinal logistic regression.

RESULTS

The prevalence of activity reduction in life domains was higher than the Canadian general population (49% versus 21%), as was needing assistance with at least one activity of daily living (17% versus 5%). Prior to adjusting for health conditions, disability odds were elevated for increased age, females, non-degree post-secondary graduation, low income, junior non-commissioned members, deployment, low social support, low mastery, high life stress, and weak sense of community belonging. Reduced odds were found for private/recruit ranks. Disability odds were highest for chronic pain (10.9), any mental health condition (2.7), and musculoskeletal conditions (2.6), and there was a synergistic additive effect of physical and mental health co-occurrence.

CONCLUSIONS

Disability, measured as activity limitation, was associated with a range of personal and environmental factors and health conditions, indicating multifactorial and multidisciplinary approaches to disability mitigation.