Canada Graduate Scholarship Research Articles

The Jejunum and Ileum Mediate Increased Calcium Absorption for Bone Mineralization During Postnatal Development via TRPV6 and Cav1.3 (OR26-07-19)

ObjectivesIntestinal Ca2+ absorption early in life is vital to achieving optimal bone mineralization. The molecular details of intestinal Ca2+ absorption have been defined in adults, after peak bone mass has been reached, but are largely unexplored during development. We sought to delineate the molecular details of transcellular Ca2+ absorption across the small intestine which facilitate a positive calcium balance during growth. MethodsWe used wildtype, Cav1.3 knockout and Trpv6 mutant mice. Expression of small intestinal and renal calcium transport genes was assessed using quantitative PCR. Net transcellular 45-calcium flux across intestinal segments was measured in Ussing chambers. Femurs we analyzed using micro-CT and histology. ResultsSignificant TRPV6 mediated Ca2+ flux across the duodenum was absent in pre-weaned (P14) mice but occurred post-weaning. In contrast, we found significant transcellular Ca2+ absorption in the jejunum and ileum at P14 but not 2 months. TRPV6 and Cav1.3 are necessary for this jejunal absorption and Cav1.3 appears to mediate absorption across the ileum although compensation is present in knockout pups. Knockout of Cav1.3 induces a compensatory increase in renal Ca2+ reabsorption in P14 mice although these pups have increased growth plate thickness suggesting delayed bone mineralization. ConclusionsThis work provides molecular details of how the small intestine facilitates increased demand for Ca2+ early in life to meet the requirements of growth and highlights the complexity of the multiple mechanisms involved in achieving a positive Ca2+ balance. Funding SourcesThis work is funded by grants from the Women and Children’s Health Research Institute, supported by the Stollery Children’s Hospital Foundation, and the National Sciences and Engineering Research Council to RTA, who is the Canada Research Chair in Renal Epithelial Transport Physiology. MRB is supported by a Vanier Canada Graduate Scholarship, Alberta Innovates Clinician Fellowship and an NSERC Michael Smith Foreign Study Supplement. H. Dimke is funded by the Danish Medical Research Council. Work at UdS was funded by Deutsche Forschungsgemeinschaft (DFG) by IRTG1830 (to JE, VF), Sonderforschungsbereich (SFB) 894 (to JE, PW) and SFB TRR152 (to VF).

Oxygen Uptake Kinetics During the Different Phases of the Menstrual and Oral Contraceptive Cycles

PURPOSE: To examine whether oxygen uptake (V̇O2) kinetics changes across the phases of the menstrual and oral contraceptive cycles. METHODS: Fourteen highly active women who were either non-oral contraceptive users (n=7, 28±6 yrs.) or monophasic oral contraceptive users (n=7, 22±3 yrs.) participated in the study. The time-constant of the V̇O2 kinetics response (τV̇O2) was determined by ensemble-averaging the V̇O2 response measured during three consecutive step-transitions in work rate, from 20 Watts (W) to a moderate-intensity work rate of 80 W. Each step was six minutes in duration. The test was completed during the menstruation phase of the cycles (follicular phase for non-oral contraceptive users or “inactive pill” phase for oral contraceptive users) and repeated during the respective non-menstruating phase (luteal phase or “active pill” phase). An ovulation test was used to validate the menstrual cycle phase. A metabolic cart was used to continuously measure expired gas concentrations and ventilatory rates. A one-way repeated-measures ANOVA was used to compare the differences in V̇O2 kinetics across cycle phases between non-oral contraceptive and oral contraceptive users. Statistical significance was set at p<0.05. RESULTS: The time constant for the adjustment of V̇O2 was affected by cycle phases, regardless of contraception use, whereby τV̇O2 was greater in the menstruation phases of the non-oral contraceptive and oral contraceptive cycles (24±7 s) compared to the non-menstruating phases (19±5 s) (p<0.05). CONCLUSION: The speed of the V̇O2 kinetics response is affected by the phases of the menstrual and oral contraceptive cycles, such that a greater τV̇O2 is observed during the menstruation phase. Anmol T. Mattu was supported by the NSERC Alexander Graham Bell Canada Graduate Scholarship.

Comprehensive 3D Architecture of the Adult Human Trapezius: A Cadaveric Study

Musculoaponeurotic architecture describes the 3D arrangement of the contractile and connective tissue elements within a muscle, or functional partitions thereof. Without a comprehensive appreciation of these features, the certainty with which clinicians may interpret musculoskeletal imaging, assess pathology, and evaluate recovery associated with these muscles is inherently restricted. Current musculoaponeurotic literature is limited by insufficient fibre bundle (FB) sampling, lack of data regarding connective tissue elements, and 2D measurement approaches for 3D parameters. Morphometrically‐complex muscles, like trapezius, are particularly susceptible to overgeneralization using these approaches. A thorough understanding of the contractile and connective tissues of trapezius may help elucidate the etiology and pathophysiology of musculoskeletal disorders associated with this muscle. Accordingly, the primary objective of this study was to capture, quantify, and model the comprehensive 3D musculoaponeurotic architecture of the adult human trapezius muscle from cadaveric data.Ten trapezius muscles from five lightly embalmed cadavers (3F, 2M; ages 64–85 years) were meticulously dissected for this study. Contractile tissue elements were serially digitized in situ at the FB level with a MicroScribe® G digitizer and modelled in Autodesk® Maya®. The surfaces of connective tissue elements (i.e. aponeuroses) were digitized in a grid pattern and integrated into 3D musculoaponeurotic models. Architectural parameters, including FB length, pennation angle, and physiological cross‐sectional area (PCSA), were quantified for the whole muscle and each functional partition (ascending, transverse, and descending).Each trapezius muscle included a minimum of 1000 FBs. Preliminary data analyses reveal consistent patterns of relative mean FB length (ascending = descending &gt; transverse), range of FB lengths (ascending &gt; descending &gt; transverse), and PCSA (transverse &gt; ascending &gt; descending). FBs throughout the muscle volume span between independent medial and lateral aponeuroses, resulting in extensive regions of musculoaponeurotic junction. Aponeuroses are notably substantial in the medial transverse and lateral ascending partitions, while the clavicular attachment of the descending partition had minimal connective tissue present.This study presents a comprehensive 3D model of the adult human trapezius that provides a foundation for improved longitudinal assessment of pathology and continuing clinical education. Future studies will use these data to guide in vivo imaging and functional electromyographic studies investigating musculoskeletal disorders associated with trapezius, such as myofascial pain syndrome.Support or Funding InformationSponsored by a Vanier Canada Graduate Scholarship from CIHR and an Educational Advancement Stipend from the University Health Network.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Benthic-pelagic trophic coupling in an Arctic marine food web along vertical water mass and organic matter gradients

The Fisheries Joint Management Committee; ? Aboriginal Affairs and Northern Development Canada (BREA); ? Natural Resources Canada (Environmental Research Fund, Program of Energy Research and Development); ? Internal Fisheries and Oceans Canada; ? NSERC Canada Graduate Scholarship; ? Michael Smith Foreign Study Supplement; ? NSERC Discovery grants; ?

Muscle Sympathetic Nerve Responses to Passive and Active One‐legged Cycling: Insight into the Contributions of Central Command

Prior studies using neuromuscular blockade to increase perception of effort during mild or moderate intensity handgrip exercise have demonstrated that activation of higher brain regions, termed central command, contribute importantly to cardiac parasympathetic withdrawal but have limited influence on muscle sympathetic activation. The purpose of the present study was to investigate the contribution of central command to the control of muscle sympathetic nerve activity (MSNA) during dynamic one‐legged cycling. Heart rate (HR), mean arterial pressure (MAP), stroke volume, and MSNA (contralateral leg microneurography) were measured in 18 healthy participants (9 men; 22±3 yr of age) at baseline and during two minutes of upright passive cycling movement and active unloaded cycling, each separated by 10 minutes of rest. The increases in HR were greater during the first (Δ3±3 vs. Δ11±7 bpm, p&lt;0.0001) and second (Δ3±4 vs. Δ9±6 bpm, p&lt;0.0001) minute, and MAP during the second minute (Δ4±3 vs. Δ7±5 mmHg, p&lt;0.01), of active unloaded cycling compared to passive cycling movement. Stroke volume increased over time (p&lt;0.001) but was not different between passive and active unloaded cycling (p&gt;0.05). MSNA burst frequency decreased similarly during the first (Δ−4±5 vs. Δ−3±5 bursts/min, p&gt;0.05) and second (Δ−6±4 vs. Δ−4±4 bursts/min, p&gt;0.05) minute of passive and active unloaded cycling. In contrast, total MSNA demonstrated attenuated reductions during the first (Δ−3.2±3.0 vs. Δ−0.6±3.3 arbitrary units/min, p&lt;0.05 [Δ−18±16% vs. Δ0±31%, p&lt;0.05]) and second (Δ−4.5±3.3 vs. Δ−1.5±3.5 arbitrary units/min, p&lt;0.01 [Δ−28±17% vs. Δ−11±24%, p&lt;0.05]) minute of active unloaded cycling. These results support the concept that muscle sympathetic burst occurrence and strength can be regulated independently and suggest that during dynamic leg exercise central command primarily alters vasoconstrictor outflow through modulations in muscle sympathetic burst strength.Support or Funding InformationThis research was supported by a Natural Science and Engineering Research Council (NSERC) of Canada Discovery Grant (P.J.M), the Canada Foundation for Innovation (P.J.M.), and a Canadian Institutes of Health Research Fredrick Banting and Charles Best Canada Graduate Scholarship (A.V.I.).

Left ventricular contractile function is critically dependent on descending sympathetic control and can be restored with minocycline after spinal cord injury

OBJECTIVEWe and others have shown that individuals with spinal cord injury (SCI) have significantly impaired cardiac function, which likely explains this population's increased odds of developing heart disease. We recently determined that pressure and volume generating capacity are both reduced following SCI and that only volumetric indices could be restored with passive rehabilitation (i.e. passive hind‐limb cycling). Conversely, we were able to partially restore pressure generating capacity using Dobutamine, directly showing that sympathetic input to the heart is critical for the maintenance of left ventricular pressure generating capacity. To this end, we sought to determine if minocycline, which has previously been shown to preserve descending supraspinal motor connections after SCI, could restore pressure generating capacity of the heart after severe spinal cord contusion in the rodent.DESIGN/METHODMale Wistar rats (n=11) underwent T3 contusion SCI and were randomly stratified into either a treated (minocycline; n=5) or vehicle control (n=6). Minocycline was given intraperitoneally at one‐hour post injury (90mg/kg) and then every 12 hours for 14 days (45mg/kg). At two months post injury animals were anesthetized with urethane and ventilated via tracheotomy. A left ventricular pressure volume catheter was inserted via a right carotid, closed chest approach and placed into the left ventricle under pressure guidance. Basal left ventricular function was immediately assessed, followed by preload manipulation and subsequent determination of load‐independent (i.e. Ees, PRSW, dPdtmax‐EDV) function using inferior vena cava occlusions. Between group differences in load‐dependent and load‐independent function were assessed using independent samples t‐tests with significance offset at p&lt;0.05.RESULTSAnimals treated with minocycline showed significantly higher max systolic pressure (p=0.008; Figure) and dPdtmax (p=0.040) compared to vehicle. No differences in heart rate were observed between groups. Load‐independent left ventricular function was significantly higher with treatment of minocycline compared to vehicle (Ees: 1.36 ± 0.46 vs. 0.72 ± 0.35; p=0.028; dPdtmax‐EDV: 102.4 ± 16.4 vs. 41.6 ± 18.4; p&lt;0.001).CONCLUSIONSMinocycline is currently in Phase III clinical trial for the improvement of motor function after SCI. Our data provide clear evidence that minocycline is able to improve load dependent and independent left ventricular function after SCI, likely due to increased sparing of descending sympatho‐excitatory pathways to the heart and adrenal medulla. Collectively, these results demonstrate a clear line of treatment that is able to restore pressure generating capacity of the left ventricle in this population.Support or Funding InformationJW Squair is supported by: Frederick Banting and Charles Best Canada Graduate Scholarship, MD/PhD Studentship from the Canadian Institutes of Health Research, Killam Doctoral Scholarship and Four Year Fellowship from the University of British Columbia. This work was principally supported by the Heart and Stroke Foundation of Canada (CR West) and a seed grant from the International Collaboration on Repair Discoveries (AV Krassioukov).

Assessing the maternal transfer of Lactobacilli to the intestine of CD‐1 murine fetuses.

RationaleRecent research suggests that the fetus is not sterile; Gram‐positive and Gram‐negative bacteria have been detected in the human placenta, umbilical cord and meconium. In addition, maternally administered probiotic Lactobacillus rhamnosus GG during weeks 30–36 of gestation has been recovered from the feces of offspring up to 24 months of age. Similarly, in mice, Enterococcus faecium has been found in the meconium of pups whose mothers received the bacterium during pregnancy. However, this area of research is still at its infancy and mechanisms underlying maternal transfer of microorganisms still need investigation.ObjectiveTo assess whether there is maternal transfer of lactobacilli to the fetus during gestation.Study Design &amp; Methods6‐week old female CD‐1 Elite (specific pathogen free) mice were randomized to receive probiotic Lacidofil® (a mixture of L. rhamnosus R0011 and L. helveticus R0052 in a 95:5 ratio) (1×109 CFU/mL, P; n= 6) or nothing (control, C; n= 4) in their drinking water for 1 week prior to mating and throughout pregnancy. Dams were sacrificed at E19 (full gestation) and the umbilical cord, and fetal small and large intestine were collected. All procedures were conducted in a sterile facility; mice received sterile chow and water and were dissected in a biosafety cabinet. DNA from collected tissues was isolated and digital droplet PCR used to quantify total bacteria and lactobacilli while L. rhamnosus R0011 was analyzed by qPCR with strain‐specific primers.ResultsBody weight increased throughout pregnancy independently of probiotic administration, and litter size did not differ between groups (C, 12±0.41 fetuses; P, 11.83±0.54 fetuses; p= 0.83). Lactobacilli were found in all tissues studied with no difference in % lactobacilli (normalized to total bacteria) between control and probiotic‐treated dams in umbilical cord (C, 55.32 ± 10.70%; P, 46.00 ± 13.04%; p= 0. 0.6008), fetal small (C, 25.66 ± 6.528%; P, 27.62 ± 4.463%; p=0.8025) and large (C, 37.26 ± 2.781%; P, 38.88 ± 5.270%; p= 0.8214) intestine. However, the specific strain L. rhamnosus R0011 was detected in the large intestine of fetuses derived from 50% of the probiotic‐treated dams (2.06×105CFU/g – 8.55×108 CFU/g) but not in controls. Future studies will assess the microbiome of other tissues.ConclusionThese data suggest that Lactobacillus may be a predominant genus in the umbilical cord and fetal gut at term. The presence of Lactobacillus DNA in the fetal intestine supports the emerging concept of in utero microbial exposure and the role it may play in health. Future studies will assess the viability of these bacteria. Although there were differences in the outcomes for maternal transfer of probiotic L. rhamnosus R0011 to the fetuses, these preliminary results provide proof that vertical transfer of microorganisms occur during gestation and that this can be modified by diet.Support or Funding InformationFunding: ‐NSERC Discovery Grant to EMC. ‐Lallemand Health Solutions donation in support of research program to EMC ‐AH is the recipient of a NSERC Canada Graduate Scholarship for Master's (CGSM) ‐SES is the recipient of an Ontario Graduate Scholarship (OGS) ‐PMS is funded by the Canadian Institutes of Health Research (MOP‐89894 and IOP‐92890) ‐EMC holds the Lawson Family Chair in Microbiome Nutrition Research at the University of Toronto.

Identification of Dietary Patterns Associated with Chronic Disease Risk Using Hybrid Dimension Reduction Techniques: Evidence from the Canadian National Nutrition Survey

Analysing dietary patterns is an important approach for characterizing the complex relationships between foods and nutrients in etiology of obesity and other chronic diseases. Several studies have used a priori and data‐driven dimension reduction techniques for evaluating dietary patterns in relation to chronic disease risks, even though methods for applying these techniques to complex nationally‐representative nutrition surveys are not yet developed. The objective of this study was to define a novel algorithm for using hybrid dimension reduction techniques for identifying dietary patterns of Canadians most strongly associated with obesity and other chronic diseases (diabetes, cancer, and cardiovascular diseases) at the national population level. Dietary data were collected using 24‐hour dietary recalls (second recall in sub‐sample). All analyses included 11,748 participants (≥18 y) in the cross‐sectional nationally‐representative Canadian Community Health Survey 2.2 (2004/5). To ensure nationally‐representative estimates, weighting algorithm was incorporated into the partial least squares analyses (PLS), to derive an energy‐dense (ED), high‐fat (HF) and low fiber density (LFD) dietary pattern using 38 food groups. PLS is the most flexible hybrid technique for deriving dietary patterns enabling discovery of important disease‐specific dietary exposures that have not been previously identified in etiology of chronic diseases. The association of dietary patterns with obesity and chronic diseases was ascertained using weighted multinominal logistic regression‐GLM adjusted for the following covariates in successive models: age, sex, dietary misreporting, energy intakes, physical activity and smoking. Using the weighted PLS algorithm, an ED,HF,LFD dietary pattern was derived with high positive loadings for fast foods, carbonated drinks, refined grains and negative loadings for whole fruits, and vegetables (≥|0.17|). Food groups with a “high” loading were summed to form a simplified dietary pattern score. Moving from the first (healthiest) to the fourth (least healthy) quartiles of the ED,HF,LFD and the simplified dietary pattern scores was associated with increasingly elevated odds ratios (OR) for “obesity with at least one chronic disease” (diabetes, cancer and cardiovascular diseases), with individuals in quartile 4 having an OR of 2.57 (95%CI:1.75,3.76) and 2.73 (1.88,3.98), respectively (p‐trend&lt;0.0001). The associations of dietary patterns with “healthy obesity” (obesity without having a chronic disease) and “being non‐obese with at least one chronic disease” were weaker, albeit significant (p&lt;0.05). Overall, consuming an ED,HF,LFD dietary pattern was associated with significantly higher risk of obesity with and without accompanying chronic diseases. Our findings demonstrated that novel techniques for deriving dietary patterns can be modified for successful use in nationally‐representative surveys. The weighted algorithm we defined in this research can be used for deriving dietary patterns associated with chronic diseases at the national population level, improving the applicability and use of novel dietary pattern techniques by governments and researchers.Support or Funding InformationThis research was supported by a grant from the Burroughs Wellcome Fund Innovation in Regulatory Science Award, and funds to the Canadian Research Data Centre Network (CRDCN) from the Social Science and Humanities research Council (SSHRC), the Canadian Institutes of Health Research (CIHR), the Canadian Foundation for Innovation (CFI) and Statistics Canada. M.J. was funded by a Burroughs Wellcome Fund Fellowship, the Canadian Institutes of Health Research (CIHR) Vanier Canada Graduate Scholarship, the CIHR/Cancer Care Ontario (CCO) Population Intervention for Chronic Disease Prevention (PICDP): A Pan‐Canadian Fellowship, Ontario Graduate Scholarship (OGS) and the Faculty of Medicine Hunter Fellowship (University of Toronto). M.L. is the Earle W. McHenry professor and is supported through chair endowed unrestricted research funds, University of Toronto. Funders had no role in the design, analysis or writing of this article.

Adaptive capacity: from assessment to action in coastal social-ecological systems

This research was supported by the Social Science and Humanities Research Council through the Ocean Canada Partnership (Pacific Working Group). Additional support was provided to C.K.W. through an NSERC Canada Graduate Scholarship (475091) and a Pacific Institute for Climate Solutions (PICS) fellowship, and to N.J.B. through a Liber Ero Fellowship in Conservation Science, a Fulbright Visiting Scholar Award, and a Banting Postdoctoral Fellowship. J.B. was supported by the Australian Centre for International Agricultural Research project FIS/2012/074.

Abstract 3718: Sensitization of human tumor cells to chemotherapy drugs by antisense downregulation of RAD51: Targeting DNA repair to induce synthetic lethality

Abstract The inherent genomic instability of cancer cells has been exploited as a tumor-selective drug target to treat tumors that are deficient in specific mechanisms of DNA repair. Inhibitors of poly(ADP-ribose) polymerase (PARP) are routinely used clinically against tumors deficient in BRCA1 or BRCA2, due to the poor capacity of these cells to undergo homologous recombination repair (HRR). This exploitation of a tumor cell deficiency to enhance selectivity to a particular drug is “synthetic lethality” (Nature 434: 913, 2005). To make use of this phenomenon in tumors that may not be inherently hypersensitive to a particular treatment, we have sought to induce synthetic lethality by down-regulating essential components of DNA repair, in particular BRCA2, to sensitize cells to chemotherapy drugs [Mol Oncol 8(8): 1429-1440, 2014]. Given that an important function of BRCA2 is to modulate the action of RAD51 in HRR, we determined whether antisense knockdown of RAD51 could enhance tumor cell sensitivity to the PARP inhibitor olaparib and the DNA-crosslinking agent cisplatin. Four different anti-RAD51 siRNA molecules (Dharmacon), targeting coding sequences, were tested against cell lines representative of different tumor types in an in vitro assay of proliferation (non-small cell lung cancer line A549b, colon carcinoma line HT-29, and prostate carcinoma lines DU145 and LNCaP). The siRNAs, as single agents, inhibited proliferation in a concentration-dependent fashion and to varying degrees, and sensitized tumor cells to olaparib. A sequence that targeted region 1169-1187 of the RAD51 cDNA (NM_002875.4) was utilized for further studies. At concentrations of anti-RAD51 siRNA 51a that inhibited proliferation of cell lines by less than 50%, 51a enhanced cytotoxicity of olaparib by over 90% and of cisplatin by 60-90%. In all cell lines except LNCaP (with mutant BRCA2) the combination of siRNAs against RAD51 and BRCA2 acted cooperatively to enhance cytotoxicity of olaparib and cisplatin. Notably, when used together, each siRNA down-regulated expression of its respective target mRNA, as demonstrated by quantitative RT-PCR, without interfering with the activity of the other. RAD51 can be exploited clinically as a target for inherent or induced synthetic lethality to DNA-damaging agents (e.g., cisplatin) or inhibitors of DNA repair (e.g., olaparib). Such treatment can include tumors with BRCA2-deficiency, either inherent or induced, to yield at least an additive anticancer effect. MR is a scholar of the CIHR Strategic Training Program in Cancer Research and Technology Transfer (CaRTT) and a recipient of the CIHR Banting and Best Canada Graduate Scholarship. Citation Format: Peter J. Ferguson, Mateusz Rytelewski, Mark D. Vincent, James Koropatnick. Sensitization of human tumor cells to chemotherapy drugs by antisense downregulation of RAD51: Targeting DNA repair to induce synthetic lethality. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3718.

Does Installing “Healthy Eating Information” in a University Dining Hall Change Students’ Food and Beverage Choices?

The objective was to determine if the installation of “healthy eating information” in a University dining hall would influence students’ food and beverage choices. This was a pre‐post, population nutrition intervention conducted in a buffet‐style cafeteria between September 2014 and April 2015. The intervention encouraged students to “fill half their plate with fruits and vegetables” and illustrated the number of minutes of jogging it takes to burn the calories in each beverage option. The beverage choices, as well as visits to the vegetable and fruit bar, were recorded on twelve menu‐matched occasions before and after the intervention. Inventory data was collected to determine the total liters of each beverage taken and the number of fruit cases ordered. There was a significant decrease in the proportion of students selecting a sugar‐sweetened beverage before (49% of the population) versus after (41%) the intervention (p=0.004). There was also a significant increase in the proportion of students drinking water before (43%) versus after (54%) the intervention (p&lt;0.001). There were no significant changes in the proportion of students selecting each individual type of beverage and there was no change in the volume (ml) of each beverage taken. There was a significant increase in the number of students taking fruit before (30% of the population) versus after (36%) the intervention (p&lt;0.001). And the number of students visiting the vegetable bar significantly increased from 60% to 72% (p&lt;0.001). Similar trends were seen in the inventory data. These results illustrate that providing healthy eating information in settings where food choices are made, such as cafeterias, could encourage healthier choices.Support or Funding InformationVanier Canada Graduate Scholarship (MS), McHenry Unrestricted Research Grant (ML)

Oxygen Considerations in the Design of Microfluidics for Studying Oxygen Dependent ATP Release from Erythrocytes

In recent years, microfluidic devices have become increasingly popular for use in biological studies due to their cost efficiency, low sample consumption rates and length scales that are relevant to cellular biology. They are used in a wide variety of areas including cell signalling. Though microfluidics have proven to be useful in biological settings, it is important to be aware of the O2 levels to which the living cells are exposed since exposure to unphysiological levels may affect cellular function. Our interests are in the hemoglobin oxygen (O2) saturation dependent ATP release from erythrocytes. Following release, the intravascular ATP then binds to purinergic receptors on the endothelium, causing a conducted signal to upstream arterioles which then vasodilate, increasing flow to the network. This mechanism is believed to be a key player in the local regulation of O2 supply in the microvasculature. Further, ATP release has been shown to be impaired in multiple cardiovascular diseases including type II diabetes and sepsis, thus understanding this fundamental signalling phenomenon is of paramount importance. In a previous study (Sove PLOS ONE 2013), we designed and computationally modelled an idealized microfluidic system to measure the dynamics of O2‐dependent ATP release from erythrocytes in vitro. The objective of the design was to create a steep O2 gradient in the channel to cause a rapid change in hemoglobin O2 saturation and measure the corresponding levels of ATP released from the erythrocytes; this was verified with the model. Due to constraints in the fabrication process, the design was altered to one that could be fabricated using common soft lithography techniques. Early prototypes of this design did not sufficiently desaturate the erythrocytes, motivating the need for a computational model of the O2 levels in the microfluidic device. In the present study, a set of computational tools were developed to investigate the O2 levels in microfluidic systems. These tools include methods for generating the multi‐domain geometries of the microfluidic systems in three spatial dimensions, as well as methods for simulating mass transport using a finite element method. The mass transport model includes the O2 interaction with the hemoglobin in erythrocytes. The computational model confirms that our early prototypes were not sufficiently desaturating the erythrocytes (maximum desaturation &lt; 2%). This has led to the design of a new device which was guided by our computational model while considering fabrication constraints. The computational model indicates that the new prototype will perform 117.8% better at desaturating the erythrocytes compared to the original design. Thus our new prototype can be easily fabricated using common soft lithography techniques and is able to sufficiently decrease erythrocyte hemoglobin O2 saturation for our needs. In sum, our computational tools have allowed us to investigate our experimental setup in order to improve our design. These tools can also be applied to other microfluidic systems to verify that appropriate levels of O2 are being supplied. The model can also be used to account for O2 consumption by living cells (e.g. endothelial cells) governed by Michaelis‐Menton kinetics ensuring they are exposed to the intended O2 levels. The next stage of this work will validate the computational model by measuring the O2 saturation in the new prototype. This new device will then be used to measure the dynamics of ATP release in vitro.Support or Funding InformationRJ Sove is funded by a NSERC Doctoral Canada Graduate Scholarship and this project is funded by CG Ellis’ NSERC Discovery Grant

Borophosphosilicate glass � Polycaprolactone hybrid scaffolds for bone tissue engineering

Event Abstract Back to Event Borophosphosilicate glass – Polycaprolactone hybrid scaffolds for bone tissue engineering Dibakar Mondal1, 2, Kibret Mequanint1 and Amin S. Rizkalla1, 2, 3 1 The University of Western Ontario, Chemical and Biochemical Engineering, Canada 2 The University of Western Ontario, Bone and Joint Institute, Canada 3 The University of Western Ontario, Dentistry, Schulich School of Medicine & Dentistry, Canada Introduction: Scaffold materials for bone tissue engineering applications should be osteoconductive and osteoinductive while exhibiting suitable porosity to allow cell infiltration, tissue growth and metabolic waste removal. Their rate of degradation must match the rate of tissue formation [1]-[3]. Conventional bioactive composite materials have been proposed to be a solution to this problem [4]-[5]. However, these materials possess micro-scale domain sizes leading to distinct phases. This, in turn, results in their non-uniform physical, chemical, mechanical and biological properties at the nano or molecular level making them unsuitable for bone biomaterials [6]. The main objective was to synthesize and characterize a range of bioactive organic-inorganic class II hybrid biomaterials via a non-aqueous sol-gel process with poly (ԑ-caprolactone) diol (PCL) as the organic component and SiO2-P2O5-B2O3 based ternary Borophosphosilicate glass (BPSG) as the inorganic component. Materials and methods: PCL diol was end-capped with 3-Glycidoxypropyl trimethoxysilane then reacted with metal alkoxides in a non-aqueous sol-gel process to produce PCL-BPSG hybrid biomaterials. Fibrous scaffolds of the synthesized hybrids biomaterials were electrospun from the viscous sol. Results and discussion: To study organic-inorganic bridging, solid-state 29Si-MAS NMR was conducted for BPSG and 50 wt% PCL-50 wt% BPSG (50H) hybrid biomaterials (Figure 1A). In silica networks, if the silicon atom is bonded to four oxygen atoms, then the resultant structure is designated as Q network. However, if a silicon atom is bonded to three oxygen atoms and one carbon atom, then the structure is designated as T network. Both of BPSG and 50H exhibited quaternary Si-O-Si bridging networks, which is denoted as Q4 (superscript indicates the number of Si-O-Si framework connections with respect to the silicon atom). Chemical shifts at δ= -92, -100 and -109 ppm were associated with Q2, Q3 and Q4 structures respectively. Chemical shifts at δ= -57 and -64 ppm denoted as T2 and T3 were attributed to the Si-O-Si bridging networks with Si-C at one end. The control BPSG did not have any peak for T networks because it has no Si-C bonding associated with Si-O-Si bridging network. In contrast, 50H spectrum showed a T3 network since Si-C bond from PCL-Si is covalently bonded with the inorganic glass network and resulted in a class II hybrid. In the FTIR spectra of PCL-BPSG hybrids (Figure 1B), characteristic peak at 1072 cm-1 is attributed to Si-O-Si stretching and the peaks at 920 and 670 cm-1 are attributed to Si-O-B stretching vibration. SEM images of BPSG and 50H surface before and after incubation in simulated body fluid (SBF) for 7 days are shown in Figure 2. Before incubation in SBF, BPSG and PCL-BPSG hybrid exhibited smooth surfaces. After incubation for 7 days both BPSG and PCL-BPSG surfaces were covered by spherical hydroxyapatite particles. From EDX spectrum (inset of Figures 2C and 2D) the Ca/P ratio were 1.7±0.6. The fibrous scaffolds from hybrid biomaterials produced by electrospinning had diameter ranged between 100 -150 nm (figure not shown). Conclusion: PCL-BPSG class II hybrid biomaterials were successfully synthesized via a non-aqueous sol-gel process. Fibrous scaffolds of the synthesized hybrids were successfully produced by electrospinning. Hydroxyapatite deposition was observed on the hybrid materials following incubation in SBF. The synthesized hybrid biomaterials could be potential candidates for bone tissue engineering. Vanier Canada Graduate Scholarship; Natural Sciences and Engineering Research Council of Canada

HIGH MORTALITY OF FISCHER VS. SPRAGUE-DAWLEY RATS IN THE SU5416 MODEL OF SEVERE PULMONARY ARTERIAL HYPERTENSION IS ASSOCIATED WITH STRAIN-SPECIFIC FAILURE OF RIGHT VENTRICULAR ADAPTATION: EFFECTS OF CARDIAC-SPECIFIC THERAPY WITH CARDIOTROPHIN-1

HIGH MORTALITY OF FISCHER VS. SPRAGUE-DAWLEY RATS IN THE SU5416 MODEL OF SEVERE PULMONARY ARTERIAL HYPERTENSION IS ASSOCIATED WITH STRAIN-SPECIFIC FAILURE OF RIGHT VENTRICULAR ADAPTATION: EFFECTS OF CARDIAC-SPECIFIC THERAPY WITH CARDIOTROPHIN-1

IMPACT OF ETHNICITY ON LONG-TERM OUTCOMES AFTER CORONARY ARTERY BYPASS GRAFTING SURGERY: A PROPENSITY MATCHED POPULATION-BASED STUDY

IMPACT OF ETHNICITY ON LONG-TERM OUTCOMES AFTER CORONARY ARTERY BYPASS GRAFTING SURGERY: A PROPENSITY MATCHED POPULATION-BASED STUDY

Modelling of the surface emission of the low magnetic field magnetar SGR 0418+5729

SG is funded by the FONDECYT postdoctoral grant 3150428. During the preparation of this work, SG was partially funded at McGill University by NSERC via the Vanier Canada Graduate Scholarship program, and by the Fonds de Recherche du Quebec - Nature et Technologies. RP acknowledges support by NSF grant No. AST 1414246 and Chandra-Smithsonian Awards No. GO3-14060A and No. AR5-16005X. NR acknowledges support via an NWO Vidi Award. NR and DV are supported by grants AYA2012-39303 and SGR2009-811. Partial support comes from NewCompStar, COST Action MP1304. JP is supported by the grant AYA2013-42184-P.

SU-D-213-03: Towards An Optimized 3D Scintillation Dosimetry Tool for Quality Assurance of Dynamic Radiotherapy Techniques

Purpose: The purpose of this work is to simulate a multi-focus plenoptic camera used as the measuring device in a real-time three-dimensional scintillation dosimeter. Simulating and optimizing this realistic optical system will bridge the technological gap between concept validation and a clinically viable tool that can provide highly efficient, accurate and precise measurements for dynamic radiotherapy techniques. Methods: The experimental prototype, previously developed for proof of concept purposes, uses an off-the-shelf multi-focus plenoptic camera. With an array of interleaved microlenses of different focal lengths, this camera records spatial and angular information of light emitted by a plastic scintillator volume. The three distinct microlens focal lengths were determined experimentally for use as baseline parameters by measuring image-to-object magnification for different distances in object space. A simulated plenoptic system was implemented using the non-sequential ray tracing software Zemax: this tool allows complete simulation of multiple optical paths by modeling interactions at interfaces such as scatter, diffraction, reflection and refraction. The active sensor was modeled based on the camera manufacturer specifications by a 2048×2048, 5 µm-pixel pitch sensor. Planar light sources, simulating the plastic scintillator volume, were employed for ray tracing simulations. Results: The microlens focal lengths were determined to be 384, 327more » and 290 µm. A realistic multi-focus plenoptic system, with independently defined and optimizable specifications, was fully simulated. A f/2.9 and 54 mm-focal length Double Gauss objective was modeled as the system’s main lens. A three-focal length hexagonal microlens array of 250-µm thickness was designed, acting as an image-relay system between the main lens and sensor. Conclusion: Simulation of a fully modeled multi-focus plenoptic camera enables the decoupled optimization of the main lens and microlens specifications. This work leads the way to improving the 3D dosimeter’s achievable resolution, efficiency and build for providing a quality assurance tool fully meeting clinical needs. M.R. is financially supported by a Master’s Canada Graduate Scholarship from the NSERC. This research is also supported by the NSERC Industrial Research Chair in Optical Design.« less

SU‐E‐T‐443: Geometric Uncertainties in Eye Plaque Dosimetry for a Fully Loaded 16 Mm COMS Plaque

Purpose:To determine the effect of geometric uncertainties in the seed positions in a COMS eye plaque on the central axis (CAX) dose.Methods:A Silastic insert was placed into a photopolymer 3D printed 16 mm COMS plaque, which was then positioned onto a custom‐designed PMMA eye phantom. High resolution 3D images were acquired of the setup using a Siemens Inveon microPET/CT scanner. Images were acquired with the plaque unloaded and loaded with IsoAid I‐125 seed shells (lack of silver core to minimize metal artifacts). Seed positions and Silastic thickness beneath each slot were measured. The measured seed coordinates were used to alter the seed positions within a standard 16 mm COMS plaque in Plaque Simulator v5.7.3 software. Doses along the plaque CAX were compared for the original and modified plaque coordinates using 3.5 mCi seeds with treatment times set to deliver 70 Gy to tumour apexes of 3.5, 5, and 10 mm height.Results:The majority of seeds showed length‐wise displacement, and all seeds showed displacement radially outward from the eye center. The average radial displacement was 0.15 mm larger than the expected 1.4 mm offset, approximately half of which was due to increased Silastic thickness beneath each slot. The CAX doses for the modified seed positions were consistently lower for all tumour heights due to geometric displacement of the seeds; dose differences were found to increase to a maximum of 2.6% at a depth of ∼10 mm, after which they decreased due to the inverse square dose fall‐off minimizing this effect.Conclusion:This work presents initial results of a broader dosimetric uncertainty evaluation for fully loaded COMS eye plaques and demonstrates the effects of seed positioning uncertainties. The small shifts in seed depths had noticeable effects on the CAX doses indicating the importance of careful Silastic loading.Funding provided by Alberta Cancer Foundation Grant #26655, Vanier Canada Graduate Scholarship, and Alberta Innovates Health Sciences Graduate Studentship

Trans people's experiences with assisted reproduction services: a qualitative study.

What are the experiences of trans persons (i.e. those whose gender identity does not match the gender assigned to them at birth) who sought or accessed assisted reproduction (AR) services in Ontario, Canada, between 2007 and 2010? The majority of trans persons report negative experiences with AR service providers. Apart from research examining desire to have children among trans people, most of the literature on this topic has debated the ethics of assisting trans persons to become parents. To-date, all of the published research concerning trans persons' experiences with AR services is solely from the perspective of service providers; no studies have examined the experiences of trans people themselves. Secondary qualitative research study of data from nine trans-identified people and their partners (total n = 11) collected as part of a community-based study of access to AR services for sexual and gender minority people between 2010 and 2012. Trans-identified volunteers (and their partners, when applicable) who had used or attempted to access AR services since 2007 from across Ontario, Canada, participated in a 60-90 minute, semi-structured qualitative interview. Qualitative analysis was performed using a descriptive phenomenological approach. Emerging themes were continually checked against the data as part of an iterative process. The data highlight barriers to accessing AR services for trans people. Participant recommendations for improving AR service provision to better meet the needs of this population are presented. These recommendations address the following areas: (i) AR service provider education and training; (ii) service provider and clinic practices and (iii) clinic environment. The majority of study participants were trans people who identified as men and who resided in major urban areas; those living in smaller communities may have different experiences that were not adequately captured in this analysis. While existing literature debates the ethics of assisting trans people to become parents through the use of AR, our study demonstrates that they are already accessing or attempting to access these services. This reality necessitates a shift toward exploring the ways in which AR services can be improved to better meet the needs of this population, from the perspectives of both service users and service providers. This project was supported by the Canadian Institutes of Health Research-Institute of Gender and Health, in partnership with the Assisted Human Reproduction Canada: Catalyst Grant: Psychosocial Issues Associated with Assisted Human Reproduction (FRN-103595). S.M. was supported by a Canada Graduate Scholarship from the Social Science and Humanities Research Council, as well as research funding from Osgoode Hall Law School, York University. S.J.-A. was supported by an Ontario Graduate Scholarship funded by the Province of Ontario and the University of Toronto. N/A.

Citrobacter rodentium Infection Alters Murine Colonic microRNA Signature

MicroRNAs (miRs) have been suggested to play a part in the interaction between pathogenic bacteria and host cells. Citrobacter rodentium is a murine pathogen causing transmissible colonic hyperplasia and colitis with similar pathogenicity as the foodborne enterohaemorrhagic Escherichia coli O157:H7 in humans. This study aimed to examine if colonic microRNA signature is altered during C. rodentium infection. C57Bl6/J male mice were randomized to C. rodentium‐infected or control group, and sacrificed at the peak of infection (10 days post‐infection). Crypt hyperplasia and intestinal inflammation were confirmed by histology and in vivo permeability test. Colonic RNA was used to profile 578 miRs by NanoString technology. Statistics and hierarchical clustering were performed in R. Gene targets of the differentially expressed miRs were identified in silico by prediction algorithms and cross‐matching with experimentally verified targets databases. Ninety‐four miRs were differentially expressed (p&lt;0.05), with 42 downregulated and 52 upregulated vs control (0.2‐8.6 fold), and infected samples clustered together and separately from the controls based on their expression profile. Many of these miRs, including miR‐21, miR‐148a, and miR‐152, are known to regulate barrier function, cell proliferation and inflammatory pathways. Moreover, prediction analysis revealed that globally gene targets are mainly involved in cell cycle and immune response. This study shows that C. rodentium infection alters the colonic microRNA signature; differentially expressed miRs may be involved in the pathogenicity mechanism and serve as targets of nutritional or therapeutic interventions.Funding: NSERC, JP Bickell Foundation, and NSERC Alexander Graham Bell Canada Graduate Scholarship