Natural Sciences And Engineering Research Council Research Articles

Impact of chronic muscle use and disuse on innate immune signaling in skeletal muscle

Mitochondria exhibit high levels of adaptability to various stimuli such as chronic muscle use (i.e. exercise) or disuse, such as immobilization or denervation. These changes in the mitochondrial network ultimately affect the health and functioning of skeletal muscle, which contributes to whole-body metabolism, locomotion, and postural stability. It is now acknowledged that mitochondrial dysfunction can activate inflammatory pathways through the recognition of damage-associated molecular patterns (DAMPs). The objective of this study was to examine how changes in mitochondria brought about by either chronic muscle inactivity or chronic exercise training affect innate immune system activation. We hypothesized that an inverse relationship between mitochondrial content and innate immune signaling would be evident in skeletal muscle. To investigate this, skeletal muscle from the hindlimbs of mice was collected after 7 days of sciatic muscle denervation, or after 4.5 weeks of endurance swim training involving 240 minutes of daily exercise. We analyzed the expression of the NLRP3 inflammasome, innate immune system signaling proteins, mitochondrial markers, and mitochondrial DNA (mtDNA) content using western blotting, cytochrome C oxidase (COX) activity, ELISA and qPCR. Following 7 days of denervation, there was a significant decrease in both COX-IV protein and COX activity, indicating a reduction in mitochondrial content. This was accompanied by an increase (p<0.05) in NLRP3, procaspase-1, gasdermin-D (GSDMD) and its active N-terminal fragment, GSDMD-N, as well as a notable increase in IL-1β. In addition, other possible converging pathways were also upregulated including cGAS-STING, and gasdermin-E. In comparison, following exercise training, there was a significant increase in mitochondrial content, apparent through increases in COX-IV protein, COX activity and mitochondrial RNA content. This was associated with decreases in procaspase-1 and caspase-1 protein expression alongside reduced STING activation. These findings highlight an inverse relationship between mitochondrial content and the activation of several inflammatory pathways that possibly converge upon NLRP3 inflammasome activation and pyroptotic cell death, leading to detriments in skeletal muscle health. This work aims to further the understanding of innate immune signaling pathways within muscle which can potentially highlight therapeutic targets to regulate its activation under divergent metabolic conditions. This work was supported by funds from the Natural Science and Engineering Research Council (NSERC). Priyanka Khemraj is the holder of an Ontario Graduate Scholarship. David A. Hood is the holder of a Canadian Research Chair in Cell Physiology. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Activation of the Nrf-2 pathway improves the mitochondrial phenotype in skeletal muscle cells

Aging muscle displays a reduction in mitochondrial content, along with elevated reactive oxygen species (ROS) emission and reduced levels of antioxidant enzymes. These characteristics enhance tissue susceptibility to oxidative damage, facilitating sub-optimal cellular metabolism and subsequent muscle atrophy. While these perturbations to metabolic homeostasis are a natural course of the aging process, there has been ongoing research investigating how to implement interventions to reduce this decline in muscle health. Regular exercise is one possible treatment modality, however this may be unsuitable for some populations who are unable to participate due to their health status. The objective of this study was to examine the activation of the Nrf-2 pathway using the nutraceutical Sulforaphane (SFN) and evaluate its role as a potential exercise mimetic. We hypothesized that SFN would act through similar pathways activated with chronic exercise to improve mitochondrial content, respiration, and ROS emission. To address our objective, C2C12 myotubes were treated with SFN for various timepoints basally, and in the presence of the Complex-I inhibitor rotenone to induce oxidative stress. Western blotting revealed an 8-fold increase in Nrf-2 nuclear localization following 24hrs of SFN treatment, which subsequently led to the upregulation of antioxidant enzymes NQO1, Heme Oxygenase-1, catalase, glutathione reductase and Glucose-6-Phosphate Dehydrogenase by 2-to 3-fold. These protein changes, were accompanied by dramatic reductions in both total cellular and mitochondrial ROS emission with SFN, detected with CellROX Green and MitoSOX Red respectively. Interestingly, this led to an increase in mitochondrial membrane potential, detected via MitoTracker Red (MTR), despite rotenone-induced oxidative stress. Western blotting revealed TFAM upregulation at 24hrs, suggesting an increase in mitochondrial DNA (mtDNA) replication and transcription. This was corroborated by an increase in COX subunit I protein, a mitochondrially-encoded subunit of cytochrome c oxidase, as well as MitoTracker Green and MTR staining by 48hrs. Mitochondrial respiration was evaluated using Seahorse analysis, demonstrating a marked increase in ATP production as well as basal and maximal respiration. Together these data suggest that activation of the Nrf-2 pathway via SFN may lead to adaptations similar to chronic exercise. Additionally, SFN may have applications in disorders characterized by mitochondrial loss and high ROS emission. To fully elucidate the precise mechanisms underlying this agent, SFN will be combined with chronic contractile activity to determine if these two interventions operate through independent pathways. This work was supported by funds from the Natural Science and Engineering Research Council (NSERC). Sabrina Champsi is the recipient of the NSERC Alexander Graham Bell Canada Graduate Scholarship-Master’s (CGS-M). David A. Hood is the holder of a Canadian Research Chair in Cell Physiology. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The effects of partial sleep deprivation on blood pressure responses during cycling are intensity dependent

Introduction: Exaggerated blood pressure (BP) responses during exercise are associated with increased risk of clinical cardiovascular outcomes. Partial sleep deprivation (PSD), defined as ≤6 hours of sleep, can increase 24-hour ambulatory BP but the effects on exercise BP have not been studied. We hypothesized that acute PSD would augment the exercise BP response to constant load exercise (below and above estimated lactate threshold) and during a 20-min time trial. Methods: Fourteen, healthy adults (22 ± 3 years; 9 males; VO2peak: 43.2 ± 9.5 ml/kg/min [25.3-60.9]) completed a randomized crossover trial where they slept normally (normal sleep-wake schedule for each participant), or sleep was partially deprived (early awakening, 40% of normal sleep duration). Prior to the testing visits, participants completed two familiarization visits under normal sleep conditions. Each participant completed a 12-minute warm (6-minutes below estimated lactate threshold [moderate intensity; 65 ± 24 W] and 6-minutes above estimated lactate threshold but below respiratory compensation point [heavy intensity; 147 ± 60 W]) followed by a time-trial where they were asked to cycle as far as possible in 20 minutes. BP was assessed at rest (BpTRU, Medical Devices) and on the cycle ergometer every 2 minutes during the warmup and 20-minute time-trial (Tango M2, SunTech Medical). Sleep timing and duration was assessed daily for 1-week prior to each testing visit using self-report and an accelerometer worn on the non-dominate wrist (wGT3X-BT, ActiGraph). Results: Resting systolic ( P=0.08) and diastolic BP ( P=0.06) tended to be higher following PSD (normal sleep: 105 ± 8/62 ± 8 mmHg vs. PSD: 107 ± 6/64 ± 7 mmHg). PSD did not alter VO2 during the moderate- (normal sleep: 1291 ± 394 ml/min vs. PSD: 1258 ± 364 ml/min) and heavy-intensity (normal sleep: 1903 ± 758 ml/min vs. PSD: 1893 ± 724 ml/min) warmup or 20-minute time-trial (normal sleep: 2713 ± 1120 ml/min vs. PSD: 2669 ± 1134 ml/min) or distance covered (normal sleep: 10.16 ± 2.024 km vs. PSD: 10.08 ± 2.145 km) and power output (normal sleep: 175 ± 79 W vs. PSD: 173 ± 79 W) during the 20-min time-trial (all P>0.27). Systolic (normal sleep: 140 ± 17 mmHg vs. PSD: 136 ± 11 mmHg, P=0.14) and diastolic (normal sleep: 67 ± 11 mmHg vs. PSD: 69 ± 8 mmHg, P=0.44) BP did not differ during the moderate-intensity warmup following PSD. However, systolic BP was lower during the heavy-intensity warmup (normal sleep: 165 ± 25 mmHg vs. PSD: 155 ± 22 mmHg, P=0.008) and 20-minute time-trial (normal sleep: 174 ± 20 mmHg vs. PSD: 165 ± 25 mmHg, P=0.05) following PSD. No differences were observed in diastolic BP (all P>0.57). Heart rate during the moderate-intensity warmup (normal sleep: 110 ± 11 bpm vs. PSD: 110 ± 10 bpm), heavy-intensity warmup (normal sleep: 137 ± 14 bpm vs. PSD: 136 ± 14 bpm), and time-trial (normal sleep: 171 ± 16 bpm vs. PSD: 169 ± 19 bpm) did not differ between conditions (all P>0.39). Conclusion: In contrast to our hypothesis, these preliminary findings suggest that a single night of PSD results in lower systolic BP responses during heavy-intensity, but not moderate-intensity, cycling exercise. This research was supported by a Natural Science and Engineering Research Council (NSERC) of Canada Discovery Grant (P.J.M). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A Dual Bounding Framework Through Cost Splitting for Binary Quadratic Optimization

Binary quadratic programming (BQP) is a class of combinatorial optimization problems comprising binary variables, quadratic objective functions, and linear/nonlinear constraints. This paper examines a unified framework to reformulate a BQP problem with linear constraints to a new BQP with an exponential number of variables defined on a graph. This framework relies on the concept of stars in the graph to split the quadratic costs into adjacent and nonadjacent components indicating in-star and out-of-star interactions. We exploit the star-based structure of the new reformulation to develop a decomposition-based column generation algorithm. In our computational experiments, we evaluate the performance of our methodology on different applications with different quadratic structures. The quadratic component of the problem is dealt with in the column generation master problem and its subproblem. Results indicate the superiority of the framework over one of the state-of-the-art solvers, GUROBI, when applied to various benchmark reformulations with adjacent-only or sparse quadratic cost matrices. The framework outperforms GUROBI in terms of both dual bound and computational time in almost all instances. History: Accepted by Andrea Lodi, Area Editor for Design & Analysis of Algorithms—Discrete. Funding: The authors thank the Mitacs Accelerate Program for providing funding for this project. In addition, B. Rostami gratefully acknowledges the funding provided by the Canadian Natural Sciences and Engineering Research Council (NSERC) under a Discovery Grant [Grant RGPIN-2020-05395]. Supplemental Material: The online appendix is available at https://doi.org/10.1287/ijoc.2021.0186 .

Probabilistic Forecasting of Bus Travel Time with a Bayesian Gaussian Mixture Model

Accurate forecasting of bus travel time and its uncertainty is critical to service quality and operation of transit systems: it can help passengers make informed decisions on departure time, route choice, and even transport mode choice, and it also support transit operators on tasks such as crew/vehicle scheduling and timetabling. However, most existing approaches in bus travel time forecasting are based on deterministic models that provide only point estimation. To this end, we develop in this paper a Bayesian probabilistic model for forecasting bus travel time and estimated time of arrival (ETA). To characterize the strong dependencies/interactions between consecutive buses, we concatenate the link travel time vectors and the headway vector from a pair of two adjacent buses as a new augmented variable and model it with a mixture of constrained multivariate Gaussian distributions. This approach can naturally capture the interactions between adjacent buses (e.g., correlated speed and smooth variation of headway), handle missing values in data, and depict the multimodality in bus travel time distributions. Next, we assume different periods in a day share the same set of Gaussian components, and we use time-varying mixing coefficients to characterize the systematic temporal variations in bus operation. For model inference, we develop an efficient Markov chain Monte Carlo (MCMC) algorithm to obtain the posterior distributions of model parameters and make probabilistic forecasting. We test the proposed model using the data from two bus lines in Guangzhou, China. Results show that our approach significantly outperforms baseline models that overlook bus-to-bus interactions, in terms of both predictive means and distributions. Besides forecasting, the parameters of the proposed model contain rich information for understanding/improving the bus service, for example, analyzing link travel time and headway correlation using covariance matrices and understanding time-varying patterns of bus fleet operation from the mixing coefficients. Funding: This research is supported in part by the Fonds de Recherche du Quebec-Societe et Culture (FRQSC) under the NSFC-FRQSC Research Program on Smart Cities and Big Data, the Canadian Statistical Sciences Institute (CANSSI) Collaborative Research Teams grants, and the Natural Sciences and Engineering Research Council (NSERC) of Canada. X. Chen acknowledges funding support from the China Scholarship Council (CSC). Supplemental Material: The e-companion is available at https://doi.org/10.1287/trsc.2022.0214 .

A single high-fat meal impairs functional sympatholysis in young healthy adults

Introduction: A high-fat diet increases the risk of cardiovascular disease and mortality, but the underlying mechanisms remain incompletely understood. During exercise, sympathetically mediated vasoconstriction is dampened in active skeletal muscle due to the counteracting vasodilatory effects of metabolic by-products from muscle contraction. This phenomenon, termed functional sympatholysis, plays a critical role in the redistribution of cardiac output to contracting skeletal muscles to meet the metabolic demands of exercise. Whether a high-fat meal modulates the magnitude of sympatholysis is currently unknown. Herein, we tested the hypothesis that a high-fat meal would acutely impair functional sympatholysis in young healthy adults. Methods: In a randomized, controlled, and cross-over design, 14 healthy adults (8 women, 26±4 years), consumed either a high- (1030kcals, 91g fat) or a low-fat (1006kcals, 1g fat) meal on two separate days. Forearm blood flow (FBF; Doppler ultrasound) and beat-to-beat mean arterial pressure (MAP; finger photoplethysmography) were measured during sympathetic activation induced by -20 mmHg lower-body negative pressure (LBNP) applied at rest and simultaneously during rhythmic handgrip exercise at 15% and 30% maximum voluntary contraction (MVC). Measurements were taken pre-meal and at 1-, 2-, and 3-hours post-prandial. Forearm vascular conductance (FVC) was calculated as FBF/MAP and the magnitude of sympatholysis as the difference of LBNP-induced changes in FVC between handgrip and rest. Results: Prior to the high-fat meal, LBNP decreased resting FVC (Δ-57±10%), and this response was attenuated during exercise at 15% (Δ-18±8%) and 30% MVC (Δ-9±7%). After the high-fat meal, LBNP induced smaller decreases in resting FVC (1h: Δ-43±12%, 2h: Δ-45±12%, 3h: Δ-49±8%, all P≤0.01 vs. pre), but during exercise greater decreases in FVC were observed at both 15% (1h: Δ-22±10%, 2h: Δ-23±8%, 3h: Δ-25±8%, all P≤0.04 vs. pre) and 30% MVC (1h: Δ-15±8%, 2h: Δ-15±6%, 3h: Δ-16±6%, all P≤0.04 vs. pre). As a result, the high-fat meal decreased the magnitude of sympatholysis during rhythmic handgrip exercise at 15% (pre-prandial: 39±8%, 1h: 20±10%, 2h: 21±8%, 3h: 24±7%, all P≤0.001) and 30% MVC (pre-prandial: 48±11%, 1h: 28±10%, 2h: 30±11%, 3h: 33±8%, all P≤0.001). The low-fat meal did not change the magnitude of sympatholysis at either 15% (pre-prandial: 37±6%, 1h: 39±6%, 2h: 38±7%, 3h: 37±8%, all P≥0.07) or 30% MVC (pre-prandial: 45±10%, 1h: 47±8%, 2h: 47±9%, 3h: 46±7%, all P≥0.39). Conclusion: These findings demonstrate the capacity of a high-fat meal to acutely impair the ability of contracting skeletal muscle to offset the vascular responsiveness to α1-adrenoreceptor activation during low- and moderate-intensity rhythmic handgrip exercise. Natural Science and Engineering Research Council (NSERC) of Canada Discovery Grant (P.J.M) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Documenting the impacts of increasing salinity in freshwater and coastal ecosystems: Introduction to the special issue

Documenting the impacts of increasing salinity in freshwater and coastal ecosystems: Introduction to the special issue

Convergence of Finite Memory Q Learning for POMDPs and Near Optimality of Learned Policies Under Filter Stability

In this paper, for partially observed Markov decision problems (POMDPs), we provide the convergence of a Q learning algorithm for control policies using a finite history of past observations and control actions, and consequentially, we establish near optimality of such limit Q functions under explicit filter stability conditions. We present explicit error bounds relating the approximation error to the length of the finite history window. We establish the convergence of such Q learning iterations under mild ergodicity assumptions on the state process during the exploration phase. We further show that the limit fixed point equation gives an optimal solution for an approximate belief Markov decision problem (MDP). We then provide bounds on the performance of the policy obtained using the limit Q values compared with the performance of the optimal policy for the POMDP, in which we also present explicit conditions using recent results on filter stability in controlled POMDPs. Whereas there exist many experimental results, (i) the rigorous asymptotic convergence (to an approximate MDP value function) for such finite memory Q learning algorithms and (ii) the near optimality with an explicit rate of convergence (in the memory size) under filter stability are results that are new to the literature to our knowledge. Funding: This research was supported in part by the Natural Sciences and Engineering Research Council (NSERC) of Canada.

A Branch-and-Price Algorithm for the Multiple Knapsack Problem

The multiple knapsack problem is a well-studied combinatorial optimization problem with several practical and theoretical applications. It consists of packing some subset of n items into m knapsacks such that the total profit of the chosen items is maximum. A new formulation of the problem is presented, where a Lagrangian relaxation is derived, and we prove that it dominates the commonly used relaxations for this problem. We also present a Dantzig-Wolfe decomposition of the new formulation that we solve to optimality using a branch-and-price algorithm, where its main advantage comes from the fact that it is possible to control whether an item is included in some knapsack or not. An improved algorithm for solving the resulting packing subproblems is also introduced. Computational experiments then show that the new approach achieves state-of-the-art results. History: Accepted by Andrea Lodi, Area Editor for Design & Analysis of Algorithms–Discrete. Funding: This work was supported by the Canadian Natural Sciences and Engineering Research Council (NSERC) [Grants 2017-06054 and 2021-04037]. This support is gratefully acknowledged.

Zooplankton assemblage structure and diversity since pre‐industrial times in relation to land use

AbstractAimWhile it is now well accepted that human activities are having pronounced effects on natural ecosystems, regional variation in the rate and magnitude of various human impacts is unclear. Moreover, the effects of land use change on natural aquatic communities have only relatively recently begun to be explored. Our goal was to understand how and where assemblages of a central food web component of freshwater lakes have changed over the course of industrialization in relation to land use.LocationCanada.Time periodPre‐1880 AD to present.Major taxa studiedCladoceran zooplankton.MethodsAs part of the Natural Sciences and Engineering Research Council (NSERC) Canadian Lake Pulse Network, we selected 101 lakes across Canada along a gradient of human impact to analyse subfossil cladoceran assemblages from sediment cores. We examined relationships between taxonomic and functional indicators of cladoceran assemblage change among lakes and through time.ResultsContemporary assemblages were taxonomically and functionally less diverse locally relative to pre‐industrial assemblages (α‐diversity) and were structured by the degree of human impact in watersheds. Local α‐diversity losses were greatest in highly impacted lakes where agriculture and pasture are prevalent. While spatial homogenization (spatial β‐diversity) did not increase since pre‐industrial times as expected, temporal turnover (temporal β‐diversity) showed a non‐significant but increasing trend in highly impacted lakes, especially in urbanized watersheds.Main conclusionsCladoceran assemblages have changed significantly over the course of the Industrial period, and especially in more highly impacted watersheds, underscoring the important role of watershed land use in shaping diversity. However, indicators of cladoceran function have remained relatively conserved over time and land use change showed little impact on β‐diversity, despite important environmental variation. Overall, this research furthers our understanding of the health status of Canadian lakes and the consequences of human activities, especially agriculture and urbanization, on lake zooplankton.

A species by any other name would sound as sweet.

David Smith argues against the prevalent practice of naming newly discovered species after human beings.

From plant biology research to technology transfer and knowledge extension: improving food quality and mitigating environmental impacts

Academic scientists face an unpredictable path from plant biology research to real-life application. Fundamental studies of γ-aminobutyrate and carotenoid metabolism, control of Botrytis infection, and the uptake and distribution of mineral nutrients illustrate that most academic research in plant biology could lead to innovative solutions for food, agriculture, and the environment. The time to application depends on various factors such as the fundamental nature of the scientific questions, the development of enabling technologies, the research priorities of funding agencies, the existence of competitive research, the willingness of researchers to become engaged in commercial activities, and ultimately the insight and creativity of the researchers. Applied research is likely to be adopted more rapidly by industry than basic research, so academic scientists engaged in basic research are less likely to participate in science commercialization. It is argued that the merit of Discovery Grant applications to the Natural Sciences and Engineering Research Council (NSERC) of Canada should not be evaluated for their potential impact on policy and (or) technology. Matching industry funds in Canada rarely support the search for knowledge. Therefore, NSERC Discovery Grants should fund basic research in its entirety.

WOMEN ARE STILL UNDERREPRESENTED IN CORONARY HEART DISEASE RESEARCH: PERSPECTIVES FROM A SYSTEMATIC REVIEW

<h3>BACKGROUND</h3> For decades, women have been neglected in cardiovascular research. With growing evidence to support a connection between the heart and the brain, we systematically reviewed the status of women included in experimental research assessing the impact of coronary heart disease (CHD) on neuropsychological functions. <h3>METHODS AND RESULTS</h3> We conducted a systematic review and used the PRISMA guidelines to report our findings. We screened a total of 26,843 references, of which 418 remained for full-text screening and only 13 were included in the final analysis. Throughout the screening process, we excluded studies which did not include women or participants with CHD or its subtypes (e.g., myocardial infarction, angina pectoris), or did not perform a neuropsychological – or variant - assessment. During the full-text screening, we excluded studies that did not perform separate statistical analyses for sexes or for conditions (e.g., combining CHD and heart failure participants). Close to half of the studies (161 studies; 46.60%) were excluded during the full-text screening phase because there was no separate analysis for women, exhibiting the underwhelming attention given to sex differences in CHD research. Of the 13 studies kept, 11 had samples composed of 36% or fewer women, and all studies, except one, failed to report the power and effect size of their sample. Furthermore, only one study considered menstrual cycle/menopause status, although it is known to influence performance on cognitive testing and CHD progression. Demographic variables that are commonly acknowledged to be cardiovascular risk factors (e.g. cholesterol, hypertension, smoking, etc.) were often measured but rarely compared between sexes, providing an incomplete picture of the underlying factors which affect the women included in these studies. <h3>CONCLUSION</h3> Our systematic review shows that women are still strikingly underrepresented in CHD research. Based on our findings, we propose the following guidelines: 1) the number of women included in CHD research should be similar to the CHD prevalence in the general population; 2) researchers should calculate the power and effect size of their samples; 3) menstrual cycle or menopausal status should be taken into account; and 4) all demographic variables should be reported separately for men and women. These guidelines aim to improve cardiovascular research in women, so that future research trials can better represent them. <i>Natural Sciences and Engineering Research Council (NSERC)</i>

Self-renewal of peripheral nerve resident macrophage: does it represent a unique activation status?

Self-renewal of peripheral nerve resident macrophage: does it represent a unique activation status?

Impact of Coffee Containing Medium-Chain Triglyceride Oil and Ghee on Markers of Cellular Inflammation in Young Healthy Humans

ObjectivesLow-carbohydrate, high-fat “ketogenic” food supplements have become increasingly popular in recent years with claims of improving body composition and cognition, while reducing hunger. However, acute consumption of high-fat foods has been shown to promote dietary endotoxemia; the release of bacterial lipopolysaccharide from the gut into the blood, which is linked to proinflammatory responses through activating toll like receptor (TLR) 4 on circulating monocytes. Bulletproof Coffee is a popular high-fat beverage consisting of coffee, medium chain triglyceride (MCT) oil, and grass-fed ghee. The purpose of this study is to determine whether consuming this high-fat coffee beverage would impact cellular inflammation assessed by increases in the number of circulating monocytes and monocyte surface TLR4 expression. We hypothesize that consuming one high-fat “Bulletproof Coffee” will elevate concentrations of circulating monocytes and increase TLR4 expression when compared to a black coffee comparator drink. MethodsThis study is a single-blind (researcher), randomized crossover design wherein participants consume either a freshly prepared coffee (1 pod with 12oz water; ∼1 kcal), or high-fat bulletproof coffee (1 pod with 12 oz water containing 1 tbsp MCT oil and 1 tbsp ghee; 27 g fat; ∼250 kcal) separated by ∼7 days. Participants provided blood samples in the fasted state and at 60- and 180-minutes following beverage consumption. Blood samples were analyzed by flow cytometry. ResultsSix healthy adults (n = 5 females) aged 25 ± 8 years who consume coffee regularly have completed both conditions. Preliminary statistical analysis using a linear mixed model has shown no significant time x condition interaction (P = 0.184) or main effect of time (P = 0.211) for the concentration of circulating monocytes. Similarly, no interaction (P = 0.675) or main effects of time (P = 0.337) were observed for monocyte surface TLR4 expression. ConclusionsPreliminary data suggests that consuming a single high-fat bulletproof coffee does not appear to increase circulating monocyte concentrations or monocyte TLR4 expression. Further research will be required to determine whether acute consumption of a high-fat coffee beverage impacts inflammation in humans. Funding SourcesThis study is funded by a Natural Sciences and Engineering Research Council (NSERC) of Canada grant.

Electroless Deposition for Nanoscale Applications: Challenges and Opportunities

We recently developed a maskless, electroless, high-P-content, Ni(P) process to protect the final Cu bitline wiring level in our STTM MRAM test vehicles to enable functional testing in an air atmosphere at elevated temperatures for evaluation of MRAM device memory state retention. The process was developed as a replacement for the final aluminum level, and drastically shortened wafer processing cycle time. We demonstrated an electroless Ni(P) that selectively deposited on Cu bit lines with effective spacing approaching 200 nm without shorting, for coating thicknesses up to ca. 50 - 60 nm, with excellent bitline coverage (no pinholes). This was achieved through optimization of Cu surface cleanliness, surface catalyzation using an acidic Pd solution, and finally electroless Ni(P) deposition (1).Testing (electrical resistance and magnetoresistance (R & MR)) of Ni(P)-coated wafers, showed virtually unchanged R & MR for MRAM 4Kb arrays encompassing a large range of device critical dimensions (CDs). Figure 1 shows a topdown SEM image of a region of electroless Ni(P)-coated Cu bitlines.While electroless deposition is capable of depositing only a limited number of metals and alloys compared to electrodeposition, it is often easier to obtain coatings of uniform thickness and composition, since one does not have the current density uniformity problem of electrodeposition. Although it is not always possible to obtain pure materials using electroless deposition, nevertheless, materials with unique properties, such as Ni(P) (corrosion resistance), and Co(P) (magnetic properties) and related alloys e.g., Co(W)(P), are readily obtained by electroless deposition methods. These materials may be crystalline or amorphous, and the crystallization kinetics of the latter type may be strongly dependent on film thickness, and have a two-dimensional character due to interfacial effects.It is important to understand how such materials transform upon heating, given that back-end-of-line (BEOL) processing may involve temperature excursions to 400 ⁰C. We will discuss in detail the kinetics of crystallization of our high-P-content, amorphous, electroless Ni(P) films on Cu thin films using synchrotron X-Ray diffraction analysis (2). For 1 um thick Ni-P films deposited on Cu/Ta/TaN underlayer, as we increase the rates at which the temperature is raised during ramp anneals, crystallization temperatures vary from about 360C to 400C from which we extract an activation energy of 3.4 eV for this crystallization. The in-situ data also shows a gradual reduction in lattice constant for the underlying Ta layer. We will complement the synchrotron X-Ray analysis study results with TEM, SIMS and X-ray fluorescence (XRF) results of Ni(P) film composition for unpatterned and patterned (sub-micron) features.In addition to the subtlety of its mechanisms and range of solution formulations, electroless deposition has much to offer in terms of niche applications, which explains why it is often turned to first by researchers seeking creative deposition methods in the still emerging field of nanofabrication. Given the wide range of materials involved in electroless deposition, whether it is the final product, or the choice of a reasonable reducing agent, the mechanism of electroless deposition tends to be complex. This talk will include a discussion of the mechanism of electroless deposition, and whether the sought after, one-mechanism-fits-all approach, is tenable.[1]. E. J. O'Sullivan et al 2019 Meet. Abstr. MA2019-02 916; https://doi.org/10.1149/MA2019-02/15/916 [2]. Canadian Light Source Inc., 44 Innovation Boulevard Saskatoon, SK S7N 2V3, Canada. Acknowledgements The authors gratefully acknowledge the efforts of the staff of the Microelectronics Research Laboratory (MRL) at the IBM T. J. Watson Research Center, where some of the fabrication work described in this talk was carried out. Part of the research described in this paper was performed at the Canadian Light Source, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation (CFI), the Natural Sciences and Engineering Research Council (NSERC), the National Research Council (NRC), the Canadian Institutes of Health Research (CIHR), the Government of Saskatchewan, and the University of Saskatchewan.

Baroreflex Resetting of Sympathetic Action Potential Subpopulations During Fatiguing Isometric Handgrip and Post‐Exercise Circulatory Occlusion

The arterial baroreflex exerts heterogeneous control over the varying‐sized action potential (AP) subpopulations active within human muscle sympathetic nerve activity (MSNA) under baseline conditions. How baroreflex control of sympathetic AP discharge becomes reset to facilitate sympathoexcitation during physical exercise remains to be investigated. Therefore, we quantified the baroreflex gain for each sympathetic AP cluster (i.e., reflecting different c‐fibres) within the MSNA filtered neurogram (microneurography and continuous wavelet transform) during baseline conditions (BSL), the last 2‐min of a 5‐min fatiguing isometric handgrip (20% of max; IHG), and during post‐exercise circulatory occlusion (PECO) in six healthy young participants (3 females, 23–31 years). Baroreflex gain was measured as the slope of the linear function between AP probability (%) versus diastolic blood pressure (DBP; Finometer). We classified AP clusters based on peak‐to‐peak amplitude using the following allocations: small (clusters 1–2), medium (clusters 3–8) and large (clusters 9–15). During BSL, medium AP clusters (e.g., cluster 3: −9.4 ± 2.7 %/mmHg) expressed the greatest baroreflex gains while small (e.g., cluster 1: −1.9 ± 0.4 %/mmHg) and large (e.g., cluster 9: −2.4 ± 0.9 %/mmHg) clusters expressed lesser gains (both P &lt; 0.05 vs. cluster 3). Compared to BSL, baroreflex functions for most AP clusters during IHG and PECO were reset upwards to greater firing probabilities (both Condition‐by‐Cluster Interactions: P &lt; 0.05) and rightwards to higher DBP (BSL: 69 ± 4, IHG: 81 ± 3, PECO: 79 ± 2 mmHg; both P &lt; 0.05 vs. BSL). However, compared to BSL, the gains of the AP cluster baroreflex functions remained unchanged with IHG (e.g., cluster 1: −1.6 ± 0.4, cluster 3: −8.2 ± 2.9, cluster 9: −4.3 ± 1.8 %/mmHg, Main Effect: P &gt; 0.05). Nonetheless, AP cluster gains were augmented above BSL during PECO (e.g., cluster 1: −2.6 ± 1.0, cluster 3: −16.0 ± 4.4, cluster 9: −5.5 ± 1.8 %/mmHg; Main Effect: P &lt; 0.05). IHG (e.g., cluster 15: −1.6 ± 0.5 %/mmHg) and PECO (e.g., cluster 15: −0.6 ± 0.3 %/mmHg) recruited a subpopulation of previously silent larger and faster conducting APs that expressed weak baroreflex gains. These data suggest that during fatiguing isometric handgrip exercise the interaction between the central command feature and the skeletal muscle metaboreflex resets baroreflex control of discrete AP subpopulations to higher blood pressures and greater levels of discharge. In addition to resetting the baroreflex functions, independent activation of the muscle metaboreflex augments the strength of baroreflex control over subpopulations of previously active APs.Support or Funding InformationSupported by the Natural Sciences and Engineering Research Council (NSERC) of Canada.

Cardiac Revascularization Post Myocardial Infarction Enhances Remuscularization and Improves Function

BackgroundHuman induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) offer an unprecedented opportunity to remuscularize infarcted human hearts. However, studies show that the majority of hiPSC‐CMs die post transplantation into the ischemic environment, limiting their regenerative potential and clinical application. Death of transplanted CMs occurs in the first few days post‐transplantation due to ischemia. Thus, attempts have been made to promote blood perfusion (i.e. addition of endothelial cells and/or angiogenic factors). However, these approaches require weeks for new vessels to form and to carry blood compared to the rapid death of transplanted CMs (2–3 days).PurposeOur goal was to improve the vascularization of the ischemic hearts to improve the survival of hiPSC‐CMs and increase heart remuscularization and function.MethodsWe performed left anterior descending artery (LAD) ligation in immunocompromised rats to model myocardial infarction. To improve vascularization, we used an innovative strategy consisting of ready‐made microvessels isolated from adipose tissue that form a vasculature and carry blood within the first days post subcutaneous implantation. We have co‐implanted ready‐made microvessels with hiPSC‐CMs by intra‐myocardial injection 2 weeks post LAD ligation. Cardiac function was assessed at 0, 2 and 4 weeks post‐implantation by echocardiography and by pressure‐volume loop at the endpoint (4 weeks). Immunohistochemistry and blood perfusion studies were performed at 1 and 4 weeks post‐implantation.ResultsCompared to hiPSC‐CM transplantation alone, microvessels promoted a ~600% increase in hiPSC‐CM survival with significant reduction in scar size. Echocardiography and pressure–volume (PV) loop analysis performed 4 weeks post‐MI revealed that hiPSC‐CM transplantation attenuated post‐infarct ventricular dilation and enhanced left ventricular contractility by demonstrating a significant improvement in fractional shortening (FS), ejection fraction (EF) as well as other functional parameters (end‐systolic volume, end‐diastolic volume, dP/dt max and min, Tau). Remarkably, co‐transplantation of hiPSC‐CMs with microvessels showed significantly superior functional recovery compared to hiPSC‐CMs alone in all the parameters assessed. Microvessels showed remarkable persistence and integration at both early and late time points, resulting in significantly faster blood perfusion and higher vessel density in the grafts.ConclusionThese findings provide a novel approach to cell‐based therapies for myocardial infarction whereby incorporation of ready‐made microvessels can serve as a personalized delivery system to improve functional outcomes in cell replacement therapies post‐myocardial infarction.Support or Funding InformationCanadian Institutes of Health Research (CIHR), Institute of Circulatory and Respiratory Health grant #137352 and #PJT153160. Discovery grant from the Natural Sciences and Engineering Research Council (NESERC): RGPIN 06621‐2017.

Exploiting Cell‐Instructive Nanocomposites for Tissue Engineering, Bio‐printing and Therapeutics Applications

Considerable effort has recently been directed towards the development of hydrogels for tissue engineering and printing complex tissues in 3D, as they can mimic the physical, chemical, and biological properties of most biological tissues. Dr. Paul, in his talk, will highlight the immense potential various bioactive nanomaterials (e.g. mineral based nanoparticles), biopolymers (e.g. DNA, gelatin) and their nanocomposites to develop advanced multifunctional hydrogels for additive manufacturing and therapeutic delivery applications, as well as to effectively control stem cell fate in a 3D microenvironment.Support or Funding InformationAP acknowledges the funding and support from Canada Research Chairs Program of the Natural Sciences and Engineering Research Council (NSERC) of Canada.

TAK1ng aim at mechanisms of allergic inflammation: contribution of TAK1 activity in allergen‐mediated mast cell activation

Allergic inflammatory disorders are at epidemic levels worldwide. Mast cells drive this inappropriate immune response via release of a variety of pro‐inflammatory mediators in response to environmental cues detected by the IgE‐FcɛRI complex, but the contributing molecular mechanisms are not fully understood. Transforming growth factor β‐activated kinase 1 (TAK1) is a known participant in related signaling through both the MAPK and NFκB pathways; however, the role of TAK1 in IgE‐FcɛRI mediated signaling and resultant allergic inflammation remains unknown. This study was carried out to assess the role of TAK1 in IgE‐mediated mast cell activation and to determine the effect its inhibition would have on the severity of an allergic inflammatory response. Assessment of the role of TAK1 was conducted by exploiting the characterized inhibitory function of 5Z‐7‐oxozeaenol (OZ), a resorcylic acid lactone established to be an ATP‐competitive selective inhibitor of TAK1. Bone marrow‐derived mast cells were sensitized with allergen‐specific IgE and treated with the corresponding allergen for various times in the presence or absence of OZ. Mast cell signaling was measured by western blotting, induced gene expression by qPCR, pro‐inflammatory mediator release by ELISA, mast cell degranulation by β‐hexosaminidase release assay, and calcium mobilization alterations via Indo‐1 based spectrofluorometry. We detect novel activation of TAK1 at Ser412 in response to IgE‐mediated activation under SCF‐c‐kit potentiation in a mast cell‐driven response characteristic of allergic inflammation, which is potently blocked by TAK1 inhibitor OZ. We therefore interrogated the role of TAK1 in a series of mast cell mediator responses using IgE‐sensitized murine bone marrow‐derived mast cells, stimulated with allergen under several TAK1 inhibition strategies. TAK1 inhibition resulted in significant impairment in the phosphorylation of MAPKs p38, ERK, and JNK; and mediation of the NFκB pathway via IκBα. Impaired gene expression and near abrogation in release of pro‐inflammatory cytokines TNF (p&lt;0.0001), IL‐6 (p&lt;0.0001), IL‐13 (p&lt;0.0001), and chemokines CCL1 (p=0.0002), and CCL2 (p&lt;0.0001) was detected. Finally, a significant inhibition of mast cell degranulation (p&lt;0.0001), accompanied by an impairment in calcium mobilization, was observed in the TAK1‐inhibited cells. These results suggest that TAK1 acts as a signaling node, not only linking the MAPK and NFκB pathways in driving the late‐phase response, but also initiation of the degranulation mechanism of the mast cell early‐phase response following allergen recognition and may warrant consideration in future therapeutic development.Support or Funding InformationFunding: This work was supported by the Natural Sciences and Engineering Research Council (NSERC), the Canada Foundation for Innovation (CFI), the Ontario Research Fund (ORF), and Ontario Graduate Scholarships.