Hypothalamic DNA 5-hydroxymethylation levels are altered by diet-induced weight gain during the development of obesity in a sex-specific manner.

Obesity is a major health concern that is associated with altered gene transcription in the hypothalamus. However, the mechanisms controlling this gene expression dysregulation remain largely unknown. DNA 5-hydroxymethylation (5-hmC) is a potent transcriptional activator that is expressed at 10 times higher levels in the brain than the periphery. Despite this, no study has examined if DNA 5-hmC is altered in the brain following exposure to obesogenic diets or contributes to abnormal weight gain over time. Here, we used a rodent diet-induced obesity model in combination with quantitative molecular assays and CRISPR-dCas9 manipulations to test the role of hypothalamic DNA 5-hmC in abnormal weight gain in male and female rats. We found that males, but not females, have decreased levels of DNA 5-hmC in the hypothalamus following exposure to a high fat diet, which directly correlate with increased body weight. Short-term exposure to a high fat diet, which does not result in significant weight gain, resulted in decreased hypothalamic DNA 5-hmC levels, suggesting these changes occur prior to obesity development. Moreover, decreases in DNA 5-hmC persist even after the high fat diet is removed, though the extent of this is diet-dependent. Importantly, CRISPR-dCas9-mediated upregulation of DNA 5-hmC enzymes in the male, but not female, ventromedial nucleus of the hypothalamus significantly reduced the percentage of weight gained on the high fat diet relative to controls. These results suggest that hypothalamic DNA 5-hmC is an important sex-specific regulator of abnormal weight gain following exposure to high fat diets.

Tools to guide clinical discussions on physical activity, sedentary behaviour, and/or sleep for health promotion between primary care providers and adults accessing care: a scoping review.

BACKGROUND: Health care providers have reported low knowledge, skill, and confidence for discussing movement behaviours (i.e., physical activity, sedentary behaviour, and sleep), which may be improved with the use of tools to guide movement behaviour discussions in their practice. Past reviews have examined the psychometric properties, scoring, and behavioural outcomes of physical activity discussion tools. However, the features, perceptions, and effectiveness of discussion tools for physical activity, sedentary behaviour, and/or sleep have not yet been synthesized. The aim of this review was to report and appraise tools for movement behaviour discussions between health care providers and adults 18 + years in a primary care context within Canada or analogous countries. METHODS: An integrated knowledge translation approach guided this review, whereby a working group of experts in medicine, knowledge translation, communications, kinesiology, and health promotion was engaged from research question formation to interpretation of findings. Three search approaches were used (i.e., peer-reviewed, grey literature, and forward searches) to identify studies reporting on perceptions and/or effectiveness of tools for physical activity, sedentary behaviour, and/or sleep. The quality of included studies was assessed using the Mixed Methods Appraisal Tool. RESULTS: In total, 135 studies reporting on 61 tools (i.e., 51 on physical activity, one on sleep, and nine combining two movement behaviours) met inclusion criteria. Included tools served the purposes of assessment (n = 57), counselling (n = 50), prescription (n = 18), and/or referral (n = 12) of one or more movement behaviour. Most tools were used or intended for use by physicians, followed by nurses/nurse practitioners (n = 11), and adults accessing care (n = 10). Most tools were also used or intended to be used with adults without chronic conditions aged 18-64 years (n = 34), followed by adults with chronic conditions (n = 18). The quality of the 116 studies that evaluated tool effectiveness varied. CONCLUSIONS: Many tools were positively perceived and were deemed effective at enhancing knowledge of, confidence for, ability in, and frequency of movement behaviour discussions. Future tools should guide discussions of all movement behaviours in an integrated manner in line with the 24-Hour Movement Guidelines. Practically, this review offers seven evidence-based recommendations that may guide future tool development and implementation.

Controlling hypothalamic DNA methylation at the Pomc promoter does not regulate weight gain during the development of obesity.

Obesity is a complex medical condition that is linked to various health complications such as infertility, stroke, and osteoarthritis. Understanding the neurobiology of obesity is crucial for responding to the etiology of this disease. The hypothalamus coordinates many integral activities such as hormone regulation and feed intake and numerous studies have observed altered hypothalamic gene regulation in obesity models. Previously, it was reported that the promoter region of the satiety gene, Pomc, has increased DNA methylation in the hypothalamus following short-term exposure to a high fat diet, suggesting that epigenetic-mediated repression of hypothalamic Pomc might contribute to the development of obesity. However, due to technical limitations, this has never been directly tested. Here, we used the CRISPR-dCas9-TET1 and dCas9-DNMT3a systems to test the role of Pomc DNA methylation in the hypothalamus in abnormal weight gain following acute exposure to a high fat diet in male rats. We found that exposure to a high fat diet increases Pomc DNA methylation and reduces gene expression in the hypothalamus. Despite this, we found that CRISPR-dCas9-TET1-mediated demethylation of Pomc was not sufficient to prevent abnormal weight gain following exposure to a high fat diet. Furthermore, CRISPR-dCas9-DNMT3a-mediated methylation of Pomc did not alter weight gain following exposure to standard or high fat diets. Collectively, these results suggest that high fat diet induced changes in Pomc DNA methylation are a consequence of, but do not directly contribute to, abnormal weight gain during the development of obesity.

Mental health and addiction health service use by physicians compared to non-physicians before and during the COVID-19 pandemic: A population-based cohort study in Ontario, Canada.

BACKGROUND: The Coronavirus Disease 2019 (COVID-19) pandemic has exacerbated mental health challenges among physicians and non-physicians. However, it is unclear if the worsening mental health among physicians is due to specific occupational stressors, reflective of general societal stressors during the pandemic, or a combination. We evaluated the difference in mental health and addictions health service use between physicians and non-physicians, before and during the COVID-19 pandemic. METHODS AND FINDINGS: We conducted a population-based cohort study in Ontario, Canada between March 11, 2017 and August 11, 2021 using data collected from Ontario's universal health system. Physicians were identified using registrations with the College of Physicians and Surgeons of Ontario between 1990 and 2020. Participants included 41,814 physicians and 12,054,070 non-physicians. We compared the first 18 months of the COVID-19 pandemic (March 11, 2020 to August 11, 2021) to the period before COVID-19 pandemic (March 11, 2017 to February 11, 2020). The primary outcome was mental health and addiction outpatient visits overall and subdivided into virtual versus in-person, psychiatrists versus family medicine and general practice clinicians. We used generalized estimating equations for the analyses. Pre-pandemic, after adjustment for age and sex, physicians had higher rates of psychiatry visits (aIRR 3.91 95% CI 3.55 to 4.30) and lower rates of family medicine visits (aIRR 0.62 95% CI 0.58 to 0.66) compared to non-physicians. During the first 18 months of the COVID-19 pandemic, the rate of outpatient mental health and addiction (MHA) visits increased by 23.2% in physicians (888.4 pre versus 1,094.7 during per 1,000 person-years, aIRR 1.39 95% CI 1.28 to 1.51) and 9.8% in non-physicians (615.5 pre versus 675.9 during per 1,000 person-years, aIRR 1.12 95% CI 1.09 to 1.14). Outpatient MHA and virtual care visits increased more among physicians than non-physicians during the first 18 months of the pandemic. Limitations include residual confounding between physician and non-physicians and challenges differentiating whether observed increases in MHA visits during the pandemic are due to stressors or changes in health care access. CONCLUSIONS: The first 18 months of the COVID-19 pandemic was associated with a larger increase in outpatient MHA visits in physicians than non-physicians. These findings suggest physicians may have had larger negative mental health during COVID-19 than the general population and highlight the need for increased access to mental health services and system level changes to promote physician wellness.

Developing and testing the usability, acceptability, and future implementation of the Whole Day Matters Tool and User Guide for primary care providers using think-aloud, near-live, and interview procedures.

BACKGROUND: Canada's 24-Hour Movement Guidelines for Adults have shifted the focus from considering movement behaviours (i.e., physical activity, sedentary behaviour, and sleep) separately to a 24-h paradigm, which considers how they are integrated. Accordingly, primary care providers (PCPs) have the opportunity to improve their practice to promote all movement behaviours cohesively. However, PCPs have faced barriers to discussing physical activity alone (e.g., time, competing priorities, inadequate training), leading to low frequency of physical activity discussions. Consequently, discussing three movement behaviours may seem challenging. Tools to facilitate primary care discussions about physical activity have been developed and used; however, few have undergone usability testing and none have integrated all movement behaviours. Following a synthesis of physical activity, sedentary behaviour, and sleep tools for PCPs, we developed the Whole Day Matters Tool and User Guide that incorporate all movement behaviours. The present study aimed to explore PCPs' perceptions on the usability, acceptability, and future implementation of the Whole Day Matters Tool and User Guide to improve their relevancy among PCPs. METHODS: Twenty-six PCPs were observed and audio-video recorded while using the Tool and User Guide in a think-aloud procedure, then in a near-live encounter with a mock service-user. A debriefing interview using a guide informed by Normalization Process Theory followed. Recordings were transcribed verbatim and analysed using content analysis and a critical friend to enhance rigour. RESULTS: PCPs valued aspects of the Tool and User Guide including their structure, user-friendliness, visual appeal, and multi-behaviour focus and suggested modifications to improve usability and acceptability. Findings are further discussed in the context of Normalization Process Theory and previous literature. CONCLUSIONS: The Tool and User Guide were revised, including adding plain language, reordering and renaming sections, reducing text, and clarifying instructions. Results also informed the addition of a Preamble and a Handout for adults accessing care (i.e., patients/clients/service-users) to explain the evidence underpinning the 24-Hour Movement Guidelines for Adults and support a person-centered approach. These four resources (i.e., Tool, User Guide, Preamble, Handout) have since undergone a consensus building process to arrive at their final versions before being disseminated into primary care practice.

Neuronal and astrocytic protein degradation are critical for fear memory formation.

Strong evidence has implicated proteasome-mediated protein degradation in the memory consolidation process. However, due to the use of pharmacological approaches, the cell type specificity of this remains unknown. Here, we used neuron-specific and novel astrocyte-specific CRISPR-dCas9-KRAB-MECP2 plasmids to inhibit protein degradation in a cell type-specific manner in the amygdala of male rats. We found that while inhibition of neuronal, but not astrocytic, protein degradation impaired performance during the training session, both resulted in impaired contextual fear memory retention. Together, these data provide the first evidence of a cell type-specific role for protein degradation in the memory consolidation process.

Short-term exposure to an obesogenic diet causes dynamic dysregulation of proteasome-mediated protein degradation in the hypothalamus of female rats.

OBJECTIVES: Previous work has shown that exposure to a high fat diet dysregulates the protein degradation process in the hypothalamus of male rodents. However, whether this occurs in a sex-independent manner is unknown. The objective of this study was to determine the effects of a short-term obesogenic diet on the ubiquitin-proteasome mediated protein degradation process in the hypothalamus of female rats. METHODS: We fed young adult female rats a high fat diet or standard rat chow for 7 weeks. At the end of the 7th week, animals were euthanized and hypothalamus nuclear and cytoplasmic fractions were collected. Proteasome activity and degradation-specific (K48) ubiquitin signaling were assessed. Additionally, we transfected female rats with CRISPR-dCas9-VP64 plasmids in the hypothalamus prior to exposure to the high fat diet in order to increase proteasome activity and determine the role of reduced proteasome function on weight gain from the obesogenic diet. RESULTS: We found that across the diet period, females gained weight significantly faster on the high fat diet than controls and showed dynamic downregulation of proteasome activity, decreases in proteasome subunit expression and an accumulation of degradation-specific K48 polyubiquitinated proteins in the hypothalamus. Notably, while our CRISPR-dCas9 manipulation was able to selectively increase some forms of proteasome activity, it was unable to prevent diet-induced proteasome downregulation or abnormal weight gain. CONCLUSIONS: Collectively, these results reveal that acute exposure to an obesogenic diet causes reductions in the protein degradation process in the hypothalamus of females.

Primary Care Physician Use and Frequency of Visits Among Physicians in Ontario, Canada.

Importance: Maintaining a healthy physician workforce includes the routine use of primary care physician (PCP) services; however, physicians may face barriers to attaining formal care. Objective: To analyze access to and frequency of visits to PCPs among physicians compared with nonphysicians. Design, Setting, and Participants: This population-based, retrospective cohort study used registration data from the College of Physicians and Surgeons of Ontario, Canada, from January 1, 1990, to March 31, 2018. Data for all newly practicing physicians as of March 31, 2018, were linked to Ontario health administrative databases. Data were analyzed from August 25, 2020, to August 6, 2021. Main Outcomes and Measures: The main outcomes were enrollment in a PCP practice and visits with a PCP. Generalized estimating equations compared primary care visits between physicians and nonphysicians, matched 1:5 based on age, sex, neighborhood income quintile, and health region. Results: Among 19 581 physicians (mean [SD] age, 43.99 [8.94] years; 53.27% male) matched to 97 905 nonphysicians, physicians were less likely to be enrolled with a PCP than were nonphysicians (81.8% vs 86.4%; absolute difference, 4.6%; adjusted odds ratio [OR], 0.75; 95% CI, 0.72-0.79) and had fewer primary care visits during the preceding 2 years (median [IQR], 2 [0-4] vs 4 [1-7]; adjusted relative rate ratio [RRR], 0.59; 95% CI, 0.58-0.60). Physicians aged 40 years or older and male physicians were less likely to be rostered (ages 40-44 years: OR, 0.70 [95% CI, 0.64-0.77]; male: OR, 0.60 [95% CI, 0.57-0.63]) and more likely to have a lower frequency of PCP visits (ages 40-44 years: RRR, 0.53 [95% CI, 0.51-0.56]; male: RRR, 0.50 [95% CI, 0.50-0.51]) compared with nonphysicians. Conclusions and Relevance: In this retrospective cohort study, enrollment with a PCP practice and frequency of visits were lower among physicians compared with a matched general population of nonphysicians. Individual, system, and medical cultural factors associated with these results need to be better understood so that physicians can take better care of themselves and their patients.

Suicide and Self-Harm Among Physicians in Ontario, Canada.

BACKGROUND: Studies of occupation-associated suicide suggest physicians may be at a higher risk of suicide compared to nonphysicians. We set out to assess the risk of suicide and self-harm among physicians and compare it to nonphysicians. METHODS: We conducted a population-based, retrospective cohort study using registration data from the College of Physicians and Surgeons of Ontario from 1990 to 2016 with a follow-up to 2017, linked to Ontario health administrative databases. Using age- and sex-standardized rates and inverse probability-weighted, cause-specific hazards regression models, we compared rates of suicide, self-harm, and a composite of either event among all newly registered physicians to nonphysician controls. RESULTS: Among 35,989 physicians and 6,585,197 nonphysicians, unadjusted suicide events (0.07% vs. 0.11%) and rates (9.44 vs. 11.55 per 100,000 person-years) were similar. Weighted analyses found a hazard ratio of 1.05 (95% confidence interval: 0.69 to 1.60). Self-harm requiring health care was lower among physicians (0.22% vs. 0.46%; hazard ratio: 0.65, 95% confidence interval: 0.52 to 0.82), as was the composite of suicide or self-harm (hazard ratio: 0.70, 95% confidence interval: 0.57 to 0.86). The composite of suicide or self-harm was associated with a history of a mood or anxiety disorder (odds ratio: 2.84, 95% confidence interval: 1.17 to 6.87), an outpatient mental health visit in the past year (odds ratio: 3.08, 95% confidence interval: 1.34 to 7.10) and psychiatry visit in the preceding year (odds ratio: 3.87, 95% confidence interval: 1.67 to 8.95). INTERPRETATION: Physicians in Ontario are at a similar risk of suicide deaths and a lower risk of self-harm requiring health care relative to nonphysicians. Risk factors associated with suicide or self-harm may help inform prevention programs.

Physician Health Care Visits for Mental Health and Substance Use During the COVID-19 Pandemic in Ontario, Canada.

Importance: Physicians self-report high levels of symptoms of anxiety and depression, and surveys suggest these symptoms have been exacerbated by the COVID-19 pandemic. However, it is not known whether pandemic-related stressors have led to increases in health care visits related to mental health or substance use among physicians. Objective: To evaluate the association between the COVID-19 pandemic and changes in outpatient health care visits by physicians related to mental health and substance use and explore differences across physician subgroups of interest. Design, Setting, and Participants: A population-based cohort study was conducted using health administrative data collected from the universal health system (Ontario Health Insurance Plan) of Ontario, Canada, from March 1, 2017, to March 10, 2021. Participants included 34 055 physicians, residents, and fellows who registered with the College of Physicians and Surgeons of Ontario between 1990 and 2018 and were eligible for the Ontario Health Insurance Plan during the study period. Autoregressive integrated moving average models and generalized estimating equations were used in analyses. Exposures: The period during the COVID-19 pandemic (March 11, 2020, to March 10, 2021) compared with the period before the pandemic. Main Outcomes and Measures: The primary outcome was in-person, telemedicine, and virtual care outpatient visits to a psychiatrist or family medicine and general practice clinicians related to mental health and substance use. Results: In the 34 055 practicing physicians (mean [SD] age, 41.7 [10.0] years, 17 918 [52.6%] male), the annual crude number of visits per 1000 physicians increased by 27%, from 816.8 before the COVID-19 pandemic to 1037.5 during the pandemic (adjusted incident rate ratio per physician, 1.13; 95% CI, 1.07-1.19). The absolute proportion of physicians with 1 or more mental health and substance use visits within a year increased from 12.3% before to 13.4% during the pandemic (adjusted odds ratio, 1.08; 95% CI, 1.03-1.14). The relative increase was significantly greater in physicians without a prior mental health and substance use history (adjusted incident rate ratio, 1.72; 95% CI, 1.60-1.85) than in physicians with a prior mental health and substance use history. Conclusions and Relevance: In this study, the COVID-19 pandemic was associated with a substantial increase in mental health and substance use visits among physicians. Physician mental health may have worsened during the pandemic, highlighting a potential greater requirement for access to mental health services and system level change.

Ubiquitination of Histone H2B by Proteasome Subunit RPT6 Controls Histone Methylation Chromatin Dynamics During Memory Formation.

BACKGROUND: Posttranslational histone modifications play a critical role in the regulation of gene transcription underlying synaptic plasticity and memory formation. One such epigenetic change is histone ubiquitination, a process that is mediated by the ubiquitin-proteasome system in a manner similar to that by which proteins are normally targeted for degradation. However, histone ubiquitination mechanisms are poorly understood in the brain and in learning. In this article, we describe a new role for the ubiquitin-proteasome system in histone crosstalk, showing that learning-induced monoubiquitination of histone H2B (H2Bubi) is required for increases in the transcriptionally active H3 lysine 4 trimethylation (H3K4me3) mark at learning-related genes in the hippocampus. METHODS: Using a series of molecular, biochemical, electrophysiological, and behavioral experiments, we interrogated the effects of short interfering RNA-mediated knockdown and CRISPR (clustered regularly interspaced short palindromic repeats)-mediated upregulation of ubiquitin ligases, deubiquitinating enzymes and histone methyltransferases in the rat dorsal hippocampus during memory consolidation. RESULTS: We show that H2Bubi recruits H3K4me3 through a process that is dependent on the 19S proteasome subunit RPT6 and that a loss of H2Bubi in the hippocampus prevents learning-induced increases in H3K4me3, gene transcription, synaptic plasticity, and memory formation. Furthermore, we show that CRISPR-dCas9-mediated increases in H2Bubi promote H3K4me3 and memory formation under weak training conditions and that promoting histone methylation does not rescue memory impairments resulting from loss of H2Bubi. CONCLUSIONS: These results suggest that H2B ubiquitination regulates histone crosstalk in learning by way of nonproteolytic proteasome function, demonstrating a novel mechanism by which histone modifications are coordinated in response to learning.

Males and females differ in the regulation and engagement of, but not requirement for, protein degradation in the amygdala during fear memory formation.

Over the last decade, strong evidence has emerged that protein degradation mediated by the ubiquitin-proteasome system is critical for fear memory formation in the amygdala. However, this work has been done primarily in males, leaving unanswered questions about whether females also require protein degradation during fear memory formation. Here, we found that male and female rats differed in their engagement and regulation of, but not need for, protein degradation in the amygdala during fear memory formation. Male, but not female, rats had increased protein degradation in the nuclei of amygdala cells after fear conditioning. Conversely, females had elevated baseline levels of overall ubiquitin-proteasome activity in amygdala nuclei. Gene expression and DNA methylation analyses identified that females had increased baseline expression of the ubiquitin coding gene Uba52, which had increased DNA 5-hydroxymethylation (5hmc) in its promoter region, indicating a euchromatin state necessary for increased levels of ubiquitin in females. Consistent with this, persistent CRISPR-dCas9 mediated silencing of Uba52 and proteasome subunit Psmd14 in the amygdala reduced baseline protein degradation levels and impaired fear memory in male and female rats, while enhancing baseline protein degradation in the amygdala of both sexes promoted fear memory formation. These results suggest that while both males and females require protein degradation in the amygdala for fear memory formation, they differ in their baseline regulation and engagement of this process following learning. These results have important implications for understanding the etiology of sex-related differences in fear memory formation.

Medical student wellness in Canada: time for a national curriculum framework.

There is substantial evidence showing that medical student wellness is a worsening problem in Canada. It is apparent that medical students' wellness deteriorates throughout their training. Medical schools and their governing bodies are responding by integrating wellness into competency frameworks and accreditation standards through a combination of system- and individual-level approaches. System-level strategies that consider how policies, medical culture, and the "hidden curriculum" impact student wellness, are essential for reducing burnout prevalence and achieving optimal wellness outcomes. Individual-level initiatives such as wellness programming are widespread and more commonly used. These are often didactic, placing the onus on the student without addressing the learning environment. Despite significant progress, there is little programming consistency across schools or training levels. There is no wellness curriculum framework for Canadian undergraduate medical education that aligns with residency competencies. Creating such a framework would help align individual- and system-level initiatives and smooth the transition from medical school to residency. The framework would organize goals within relevant wellness domains, allow for local adaptability, consider basic learner needs, and be learner-informed. Physicians whose wellness has been supported throughout their training will positively contribute to the quality of patient care, work environments, and in sustaining a healthy Canadian population.

Nous disposons d'un grand nombre de données concrètes démontrant que le bien-être des étudiants en médecine au Canada se détériore tout au long de leur cheminement universitaire et que le problème s'aggrave. Alliant les approches systémique et individuelle, les facultés de médecine et leurs directions réagissent en intégrant le bien-être dans les cadres de compétences et les normes d'agrément. Les stratégies systémiques, qui tiennent compte de l'impact des politiques, de la culture médicale et du «curriculum caché¼ sur le bien-être des étudiants, sont indispensables pour prévenir l'épuisement professionnel et pour obtenir des résultats optimaux en matière de bien-être. Les initiatives au niveau individuel, comme les programmes axés sur le bien-être, sont de plus en plus répandues. Ces programmes sont souvent didactiques et ils sollicitent l'étudiant sans tenir compte de l'environnement d'apprentissage. Bien que ces initiatives aient marqué des progrès importants, il y a peu d'uniformité entre les programmes des diverses facultés et entre les niveaux de formation. Il n'y a pas de cadre pédagogique pour les programmes d'études de premier cycle axés sur le bien-être au Canada s'alignant aux compétences visées dans les programmes de résidence. La création d'un tel cadre permettrait d'harmoniser les initiatives de niveau individuel et celles de niveau systémique et de faciliter la transition de la faculté de médecine vers la résidence. Il comporterait des objectifs organisés selon les domaines de bien-être pertinents, une souplesse permettant son adaptation aux divers milieux, il tiendrait compte des besoins fondamentaux des apprenants et il serait fondé sur une consultation de ces derniers. Les médecins dont le bien-être a été soutenu tout au long de leur formation contribueront de façon positive à la qualité des soins aux patients, à leur environnement de travail et au maintien d'une population canadienne en bonne santé.

Physical activity participation and mental health profiles in Canadian medical students: latent profile analysis using continuous latent profile indicators.

Rates of mental illness among Canadian medical students are higher than age-, gender-, and education-matched peers. One predictor of mental health is physical activity; though the relationship between different intensities of physical activity and mental health has not been investigated in medical students. The purpose of this study was to examine relationships between physical activity and mental health profiles in a sample of Canadian medical students. A total of N = 125 students completed an online survey. Latent profile analysis was performed to identify distinct profiles using four continuous latent profile indicators (emotional well-being, social well-being, psychological well-being,resilience). Three mental health profiles emerged, showing low (n = 18), moderate (n = 72) and high (n = 36) self-reported ratings of mental health. The classification quality was good (entropy = 0.81). Individuals in the high mental health profile engaged in more mild physical activity (M = 144.28 mins/week; SD = 22.12) and less moderate-to-vigorous physical activity (M = 195.86 mins/week; SD = 25.67) compared to students in the moderate and low profiles, though not significantly. This suggests that mild physical activity might be the most effective intensity in supporting mental health among medical students, though further research is recommended.

DNA Double-Strand Breaks Are a Critical Regulator of Fear Memory Reconsolidation.

Numerous studies have shown that following retrieval, a previously consolidated memory requires increased transcriptional regulation in order to be reconsolidated. Previously, it was reported that histone H3 lysine-4 trimethylation (H3K4me3), a marker of active transcription, is increased in the hippocampus after the retrieval of contextual fear memory. However, it is currently unknown how this epigenetic mark is regulated during the reconsolidation process. Furthermore, though recent evidence suggests that neuronal activity triggers DNA double-strand breaks (DSBs) in some early-response genes, it is currently unknown if DSBs contribute to the reconsolidation of a memory following retrieval. Here, using chromatin immunoprecipitation (ChIP) analyses, we report a significant overlap between DSBs and H3K4me3 in area CA1 of the hippocampus during the reconsolidation process. We found an increase in phosphorylation of histone H2A.X at serine 139 (H2A.XpS139), a marker of DSB, in the Npas4, but not c-fos, promoter region 5 min after retrieval, which correlated with increased H3K4me3 levels, suggesting that the two epigenetic marks may work in concert during the reconsolidation process. Consistent with this, in vivo siRNA-mediated knockdown of topoisomerase II ß, the enzyme responsible for DSB, prior to retrieval, reduced Npas4 promoter-specific H2A.XpS139 and H3K4me3 levels and impaired long-term memory, indicating an indispensable role of DSBs in the memory reconsolidation process. Collectively, our data propose a novel mechanism for memory reconsolidation through increases in epigenetic-mediated transcriptional control via DNA double-strand breaks.

Evidence-based recommendations to assist adults with depression to become lifelong movers. / Recommandations fondées sur des données probantes visant à aider les adultes atteints de dépression à rester actifs toute leur vie.

Depression is the most common and prevalent mental disorder today, affecting an estimated 1 in 4 Canadians at some point in their lifetime. Physical activity is recommended as a primary treatment for mild to moderate depression and a secondary treatment for moderate to severe depression. Despite this, specific guidelines are still lacking on how to best promote physical activity in this population. Accordingly, this policy brief provides evidence-based recommendations for primary care providers and allied health professionals to promote lifelong physical activity in individuals with depression. Recommendations include asking for permission to discuss physical activity with the individual; framing physical activity as something that they have control over in order to feel better; clarifying that incorporating even a few more minutes of weekly physical activity is better than nothing and that mild forms are enough to achieve mental health benefits; and providing choices of activities to try and accompanying them on their first few sessions. Moreover, this article highlights the importance of promoting physical activity enjoyment for this population, which can be done by guiding the individual to slowly build up the frequency, duration and intensity of activity; encouraging them to be self-compassionate toward physical activity; suggesting they engage in outdoor activity, listen to music, and/or participate with a buddy or group; and incorporate self-monitoring or journalling to solidify the link between physical activity and improved mood. Practitioners are encouraged to use these evidence-informed recommendations-especially maximizing choices, enhancing physical activity enjoyment and emphasizing personal preferences-to help individuals with depression move, recover and flourish. These recommendations may also be used to tailor future interventions and inform policy guidelines to reduce depression rates in Canada.

Physical activity is proven to prevent and treat depression. Lower levels of physical activity and mild forms are enough for mood gains. Practitioners should promote enjoyable physical activity experiences by guiding individuals with depression to slowly build up their physical activity, and by suggesting they choose activities based on preferences, play outdoors, incorporate music and/or participate with a buddy or group. Other recommendations are to ask for permission to talk about physical activity and frame it as something that can be done to feel better; clarify that a little physical activity is better than nothing; provide choices to try; and, if possible, accompany the individual on their first few sessions.

Il est prouvé que l'activité physique permet de prévenir et de traiter la dépression. Des niveaux d'activité physique même faibles et d'intensité peu élevée sont suffisants pour améliorer l'humeur. Les praticiens devraient promouvoir des expériences d'activité physique agréables en aidant les personnes atteintes de dépression à augmenter progressivement leur niveau d'activité physique et en leur suggérant de choisir des activités en fonction de leurs préférences, de pratiquer des activités en plein air, d'intégrer de la musique et d'être accompagnées d'un(e) ami(e) ou de faire partie d'un groupe. Il est également recommandé de demander la permission de parler d'activité physique ainsi que de présenter celle-ci comme un moyen de se sentir mieux, de préciser qu'un peu d'activité physique vaut mieux que rien, de proposer divers choix à expérimenter et, si possible, d'accompagner la personne lors de ses premières séances.

Dysregulation of protein degradation in the hippocampus is associated with impaired spatial memory during the development of obesity.

Studies have shown that long-term exposure to high fat and other obesogenic diets results in insulin resistance and altered blood brain barrier permeability, dysregulation of intracellular signaling mechanisms, changes in DNA methylation levels and gene expression, and increased oxidative stress and neuroinflammation in the hippocampus, all of which are associated with impaired spatial memory. The ubiquitin-proteasome system controls the majority of protein degradation in cells and is a critical regulator of synaptic plasticity and memory formation. Yet, whether protein degradation in the hippocampus becomes dysregulated following weight gain and is associated with obesity-induced memory impairments is unknown. Here, we used a high fat diet procedure in combination with behavioral and subcellular fractionation protocols and a variety of biochemical assays to determine if ubiquitin-proteasome activity becomes altered in the hippocampus during obesity development and whether this is associated with impaired spatial memory. We found that only 6 weeks of exposure to a high fat diet was sufficient to impair performance on an object location task in rats and resulted in dynamic dysregulation of ubiquitin-proteasome activity in the nucleus and cytoplasm of cells in the hippocampus. Furthermore, these changes in the protein degradation process extended into cortical regions also involved in spatial memory formation. Collectively, these results indicate that weight gain-induced memory impairments may be due to altered ubiquitin-proteasome signaling that occurs during the early stages of obesity development.

Demographic differences in Canadian medical students' motivation and confidence to promote physical activity.

BACKGROUND: Physical activity (PA) remains under prescribed by physicians. Motivation and confidence are clear drivers of frequency of promoting PA. Research shows demographic differences in physicians' preventive practices, yet none have included medical students who form habits during training. OBJECTIVES: Study objectives were to (i) examine how Canadian medical students' motivation to recommend PA to future patients differs according to six demographic variables (i.e. gender, ethnicity, year of study, university, proposed specialty and academic background) and (ii) examine how Canadian medical students' confidence to recommend PA to future patients differs according to these same demographic variables. METHODS: A cross-sectional design was used. First to fourth year medical students from three medical schools responded to an online survey (N = 221). RESULTS: Female participants were more motivated to counsel patients on PA and refer to an exercise specialist compared to males (P < 0.01). Second year students were more motivated to assess a patients' level of PA compared to third and fourth year students (P < 0.01). Students pursuing family medicine were more confident to assess and counsel compared to students pursuing paediatrics (P < 0.01). CONCLUSION: Given that motivation and confidence have a positive influence on frequency-promoting PA, these results suggest where future efforts should focus, to improve PA promotion in medical practice. Physical inactivity continues to be a major issue worldwide, and medical students as future physicians have a unique opportunity to enhance PA amongst the population.

Males and Females Differ in the Subcellular and Brain Region Dependent Regulation of Proteasome Activity by CaMKII and Protein Kinase A.

The ubiquitin-proteasome system (UPS) controls the degradation of ~90% of short-lived proteins in cells and is involved in activity- and learning-dependent synaptic plasticity in the brain. Calcium/calmodulin dependent protein kinase II (CaMKII) and Protein Kinase A (PKA) can regulate activity of the proteasome. However, there have been a number of conflicting reports regarding under what conditions CaMKII and PKA regulate proteasome activity in the brain. Furthermore, this work has been done exclusively in males, leaving questions about whether these kinases also regulate the proteasome in females. Here, using subcellular fractionation protocols in combination with in vitro pharmacology and proteasome activity assays, we investigated the conditions under which CaMKII and PKA regulate proteasome activity in the brains of male and female rats. In males, nuclear proteasome chymotrypsin activity was regulated by PKA in the amygdala but CaMKII in the hippocampus. Conversely, in females CaMKII regulated nuclear chymotrypsin activity in the amygdala, but not hippocampus. Additionally, in males CaMKII and PKA regulated proteasome trypsin activity in the cytoplasm of hippocampal, but not amygdala cells, while in females both CaMKII and PKA could regulate this activity in the nucleus of cells in both regions. Proteasome peptidylglutamyl activity was regulated by CaMKII and PKA activity in the nuclei of amygdala and hippocampus cells in males. However, in females PKA regulated nuclear peptidylglutamyl activity in the amygdala, but not hippocampus. Collectively, these results suggest that CaMKII- and PKA-dependent regulation of proteasome activity in the brain varies significantly across subcellular compartments and between males and females.