The Limiting Speed of the Bacterial Flagellar Motor

Recent experiments on the bacterial flagellar motor have shown that the structure of this nanomachine, which drives locomotion in a wide range of bacterial species, is more dynamic than previously believed. Specifically, the number of active torque-generating units (stators) was shown to vary across applied loads. This finding invalidates the experimental evidence reporting that limiting (zero-torque) speed is independent of the number of active stators. Here, we propose that, contrary to previous assumptions, the maximum speed of the motor is not universal, but rather increases as additional torque-generators are recruited. This result arises from our assumption that stators disengage from the motor for a significant portion of their mechanochemical cycles at low loads. We show that this assumption is consistent with current experimental evidence and consolidate our predictions with arguments that a processive motor must have a high duty ratio at high loads.Comment: 8 pages, 3 figures (main text); 7 pages, 3 figures (supplementary

Can language and cultural continuity protect against diabetes in First Nations communities?

Here is a plethora of deficit-focused literature and research detailing the many health conditions that disproportionately and negatively impact Indigenous peoples in North America and around the world. Type 2 diabetes in particular is often front and center, given that its incidence and prevalence have increased dramatically over the past three to four decades and its complications continue to wreak havoc in many Indigenous populations. At the same time, Indigenous peoples have been voicing a message of an association between the loss and destruction of their traditional cultures and ways of life, and the subsequent impact on their health. Focusing primarily on Canadian Indigenous populations, in this session we will 1) provide an brief overview of the burden of type 2 diabetes and its complications in Indigenous peoples; 2) describe a simple model for the underlying causes drawing attention to the fundamental role of colonial domination and cultural/language genocide; 3) detail some of our recent research related to cultural continuity, traditional language, and type 2 diabetes; and 4) provide a Cree community specific perspective on the disease

Mechanics of torque generation in the bacterial flagellar motor

The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well-established that the passage of ions down a transmembrane gradient through the stator complex provides the energy needed for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, while steric forces comprise the actual 'power stroke'. Specifically, we predict that ion-induced conformational changes about a proline 'hinge' residue in an $\alpha$-helix of the stator are directly responsible for generating the power stroke. Our model predictions fit well with recent experiments on a single-stator motor. Furthermore, we propose several experiments to elucidate the torque-speed relationship in motors where the number of stators may not be constant. The proposed model provides a mechanical explanation for several fundamental features of the flagellar motor, including: torque-speed and speed-ion motive force relationships, backstepping, variation in step sizes, and the puzzle of swarming experiments

Diabetes in Pregnancy among First Nations Women in Alberta, Canada: A Retrospective Analysis

Background In addition to increasing the risk of adverse birth outcomes, diabetes in pregnancy is thought to be an important driver of the epidemic of type 2 diabetes affecting Canada’s First Nations population. The relative contributions of gestational diabetes mellitus (GDM) and pre-existing diabetes are not well understood. We generated a comprehensive epidemiological profile of diabetes in pregnancy over a 10-year period among the First Nations population of Alberta, Canada. Methods De-identified administrative data for 427,058 delivery records were obtained for the years 2000–2009. Pregnancy risk factors and delivery outcomes were described and compared by ethnicity (First Nations vs. non-First Nations) and diabetes status. Age-adjusted prevalence values for GDM and pre-existing diabetes were calculated and were compared by ethnicity. Longitudinal changes over time were also examined. Predictors were explored using logistic regression analysis. Results First Nations women had more antenatal risk factors and adverse infant outcomes that were compounded by diabetes. First Nations descent was an independent predictor of diabetes in pregnancy (p < 0.001). GDM prevalence was significantly higher among First Nations (6.1%) compared to non-First Nations women (3.8%; p < 0.001), but prevalence values increased significantly over time only in non-First Nations women (4.5 average annual percent change; p < 0.05). The prevalence of pre-existing diabetes was stable over time in both groups, but First Nations women experienced a 2.5-fold higher overall prevalence compared with non-First Nations women (1.5% vs. 0.6%, respectively; p < 0.001). Conclusions Although First Nations women experience a higher overall prevalence of diabetes in pregnancy, the lack of increase in the prevalence over time is encouraging. However, because high-risk pregnancies and poor outcomes are more common among First Nations women, particularly those with diabetes, strategies to improve perinatal care must be implemented

Implementing Community-Engaged Participatory Research Methods in a Study of Cree Women’s Wellness: Describing Recruitment Processes and Outcomes

Background: In 2017, the Sohkitehew Group was funded to undertake research to identify wellness strategies adopted by mature women as they age in the rural Cree community of Maskwacis, Alberta. We describe our recruitment processes and outcomes for events from July 2017 to June 2018, the first phase of this research. Methodology: Data gathered from minutes of 36 Sohkitehew Working Group and two Elders Advisory Committee meetings were used to identify recruitment strategies, event characteristics and recruitment outcomes for two large community events and three Sharing Circles. Results:1. Recruitment strategies: Strategies were similar for community events and Sharing Circles: event posters were displayed throughout Maskwacis, and advertisements were broadcast by Hawk Radio and appeared in Band newsletters.2. Event Characteristics: Settings included a large community gymnasium for large events, and smaller community venues in different Bands for Sharing Circles. Traditional/cultural protocols were addressed by smudging meeting spaces, inviting community Elders to attend all events, and saying prayers. Healthy lunches were provided.3. Event attendance: The two larger community events attracted 96, and 37 participants, respectively. Sharing Circle attendance ranged from 8 to 23 participants. Conclusion: Recruitment strategies succeeded for the Sohkitehew events in Maskwacis. Prior trusting and respectful relationships with the community established over several years provided a firm basis for this research. Successful recruitment efforts required time, planning, flexibility, and careful attention to culture and tradition to meet objectives to attract participants. Similar strategies may be successful in other rural Indigenous communities if tailored for the specific needs and expectations of individual communities

Emerging Longitudinal Trends in Health Indicators for Rural Residents Participating in a Diabetes and Cardiovascular Screening Program in Northern Alberta, Canada

Background. Geographic isolation, poverty, and loss of culture/tradition contribute to “epidemic” rates of diabetes amongst indigenous Canadians. The Mobile Diabetes Screening Initiative travels to rural indigenous and other remote communities in Alberta to screen for diabetes and cardiovascular risk. We sought to examine risk factors longitudinally. Methods. Clinical and anthropometric measurements were undertaken for 809 adults (aged 20–91) between November 2003 and December 2009. For those who had more than one MDSi visit, trend estimates (actual changes) were calculated for body mass index (BMI), weight, waist circumference, hemoglobin A1c (A1c), total cholesterol, and blood pressure. Results. Among those without diabetes (N = 629), BMI and weight increased (P < .01) and blood pressure decreased (P < .05). For those with diabetes (N = 180), significant improvements (P < .05) were observed for all indicators except waist circumference. Conclusion. Improvements observed suggest that MDSi's model may effectively mediate some barriers and support subjects in managing their health

Association of Digoxin With Interstage Mortality: Results From the Pediatric Heart Network Single Ventricle Reconstruction Trial Public Use Dataset

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139107/1/jah31279.pd

CB1 Receptors Regulate Alcohol-Seeking Behavior and Alcohol Self-administration of Female Alcohol-Preferring (P) Rats

Rationale The endogenous cannabinoid (CB) system mediates a number of behaviors associated with drug-seeking and drug self-administration. In this study the effects of CB1 receptor manipulations on operant ethanol (EtOH) responding during EtOH-seeking, EtOH- relapse as well as on-going EtOH self-administration were determined. Methods Alcohol-preferring (P) rats were trained in 2-lever operant chambers to self-administer 15% EtOH (v/v) and water on a concurrent fixed-ratio 5 – fixed-ratio 1 (FR5-FR1) schedule of reinforcement in daily 1-hr sessions. After 10 weeks, rats underwent 7 extinction sessions, followed by 2 weeks in their home cages without access to EtOH or operant chambers. Rats were then returned to the operant chambers for testing of EtOH-seeking behavior (no EtOH present) for 4 sessions. After a week in their home cages following the EtOH-seeking test, rats were returned to the operant chambers with access to EtOH and water (relapse). Rats were then maintained in the operant chambers for daily 1-hr sessions with access to 15% EtOH and water for several weeks. Results The CB1 receptor antagonist (SR141716A), at doses of 1 and 2 mg/kg, i.p. reduced EtOH-seeking and transiently reduced EtOH self-administration during relapse and maintenance. Conversely, treatment with the CB1 receptor agonist CP, 55-940, at doses of 1 and 10 μg/kg i.p., increased EtOH-seeking and EtOH self-administration during relapse. Conclusions The results of this study demonstrate that activation of CB1 receptors are involved in regulating EtOH-seeking as well as the reinforcing effects of EtOH under relapse and on-going self-administration conditions

Fragmentation in Australian Commonwealth and South Australian State policy on mental health and older people: A governmentality analysis

This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 License (http://www.creativecommons.org/licenses/by-nc/3.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page(https://us.sagepub.com/en-us/nam/open-access-at-sage).Mental health care for older people is a significant and growing issue in Australia and internationally. This article describes how older people’s mental health is governed through policy discourse by examining Australian Commonwealth and South Australian State government policy documents, and commentaries from professional groups, advocacy groups and non-governmental organisations. Documents published between 2009 and 2014 were analysed using a governmentality approach, informed by Foucault. Discourses of ‘risk’, ‘ageing as decline/dependence’ and ‘healthy ageing’ were identified. Through these discourses, different neo-liberal governmental strategies are applied to ‘target’ groups according to varying risk judgements. Three policy approaches were identified where older people are (1) absent from policy, (2) governed as responsible, active citizens or (3) governed as passive recipients of health care. This fragmented policy response to older people’s mental health reflects fragmentation in the Australian policy environment. It constructs an ambiguous place for older people within neo-liberal governmental rationality, with significant effects on the health system, older people and their carers