Publications by authors named "Matthew Doyle"

56 Publications

Quantifying sprint kayak training on a flowing river: Exploring the utility of novel power measures and its relationship to measures of relative boat speed.

Eur J Sport Sci 2021 Sep 6:1-18. Epub 2021 Sep 6.

School of Human Sciences (Exercise and Sport Science). The University of Western Australia. Crawley, 6009, Australia.

Quantification of external training load for sprint kayak athletes can be challenging due to the influence of the water flow on boat velocity in a flowing river environment. Therefore, this study examined the utility of novel measures of power output (PO) and its relationship to measures of relative boat speed when training on a flowing river. Twelve (8 males, 4 female) well-trained sprint kayak athletes completed 4 separate on-water sessions comprising one time-trial session (2 × 1000-m maximal efforts) and three repeated sprint kayak training sessions (5 x split 1000-m [2 × 500-m up and down the river] submaximal efforts) in their individual (K1) kayak. For each session, a Kayak Power Meter recorded athletes' PO, and a SpeedCoach device recorded relative land-speed via a Global Positioning System (GPS) (), and relative water-speed via an impeller mounted under the boat hull (). Non-linear least squares regression were used to evaluate the curvilinear relationship between PO and speed ( and ) data. The exponents of velocity in the PO- relationship (2.87 females, 2.94 males) were closer to theoretical values (3.00) and showed greater model accuracy (root mean squared error (RMSE) = 20-26 W) than the PO- relationships (speed exponents=1.58-2.02, RMSE=31-40 W). Overall, PO measures could better account for the influence of water flow compared to traditional measures, and therefore, may be more suitable for quantifying athletes' external load in their training environment.
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http://dx.doi.org/10.1080/17461391.2021.1977393DOI Listing
September 2021

Caring for carers: Understanding the physical and psychological well-being of carers of veterans in Australia.

Health Soc Care Community 2021 May 28. Epub 2021 May 28.

Allied Health and Human Performance, Alliance for Research in Exercise, Nutrition, and Activity (ARENA), University of South Australia, Adelaide, SA, Australia.

Carers of veterans tend to put their own physical and psychological well-being needs behind the needs of the person they are caring for and often do not seek assistance for their own physical and psychological well-being. Combined, these factors lead to increased risk of acute and chronic illness and mental health issues. It is acknowledged that physical activity independently contributes to improved physical and mental health and may be a driver for mental well-being in carers. The aim of this pilot research was to understand how movement behaviour and health behaviours of carers of veterans in Australia relate to carers' physical and psychological well-being. Assessment occurred between February and July 2019 and included objective, validated measures to examine physical and psychological well-being. To assess the association between physical and psychological factors, correlational analyses were performed. Twenty-eight carers participated in the pilot study (96% female, mean age 61.6 years). Exercise capacity varied, and 84% of carers met the recommended 150 min of physical activity per week, with carers spending 8.6% of their time in moderate-to-vigorous physical activity; and 37.9% of the day sedentary. Psychological health outcomes reflect a population with high distress levels and lower than average mental well-being, but with normal resilience scores. Carers with higher levels of resilience had greater exercise capacity, covering further distance in the 6-min walk test, and as resilience increased, number of sedentary bouts decreased. This research demonstrates that there is a relationship between health behaviours and psychological well-being in carers of veterans and serving personnel. Based on the findings of this pilot study, programmes to support family carers should include information about physical activity, reducing sedentary time, and increasing resilience. Interventions designed to improve physical and psychological well-being should be trialled and evaluated for effectiveness.
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http://dx.doi.org/10.1111/hsc.13449DOI Listing
May 2021

The Effect of Geometric and Hemodynamic Parameters on Blood Flow Efficiency in Repaired Tetralogy of Fallot Patients.

Ann Biomed Eng 2021 Apr 9. Epub 2021 Apr 9.

Institute of Biomedical Engineering, University of Toronto, Toronto, Canada.

Surgical repair of Tetralogy of Fallot (TOF) involves a series of steps to remove right ventricular outflow tract and pulmonary artery obstruction. However, the large degree of anatomic variability among preoperative TOF patients may impact the effectiveness of different repair strategies and, subsequently, different geometric modifications for different patients. This study investigates the relationships between geometric and hemodynamic parameters and mechanical energy efficiency for a patient-specific dataset of 16 postoperative TOF repairs, using morphometric and statistical shape analyses, as well as computational fluid dynamics simulations with physiologically-relevant inlet and outlet boundary conditions. Quantitatively, negative correlations were found between the right and left pulmonary artery centerline tract cumulative torsion and energy efficiency (r = - 0.65, p = 0.01, for both). A positive correlation was also found for a statistical shape mode associated with skewing of the geometric sub-regions (r = 0.61, p = 0.01). Qualitatively, medium- and low-efficiency geometries exhibit disturbed flow and much more proximal vortex formation as compared to a high-efficiency geometry. Thus, it is recommended, as much as possible, to both relieve and avoid the introduction of torsion into the patient's anatomy during surgical repair of TOF.
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http://dx.doi.org/10.1007/s10439-021-02771-6DOI Listing
April 2021

BamA forms a translocation channel for polypeptide export across the bacterial outer membrane.

Mol Cell 2021 05 10;81(9):2000-2012.e3. Epub 2021 Mar 10.

Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address:

The β-barrel assembly machine (BAM) integrates β-barrel proteins into the outer membrane (OM) of Gram-negative bacteria. An essential BAM subunit (BamA) catalyzes integration by promoting the formation of a hybrid-barrel intermediate state between its own β-barrel domain and that of its client proteins. Here we show that in addition to catalyzing the integration of β-barrel proteins, BamA functions as a polypeptide export channel. In vivo structural mapping via intermolecular disulfide crosslinking showed that the extracellular "passenger" domain of a member of the "autotransporter" superfamily of virulence factors traverses the OM through the BamA β-barrel lumen. Furthermore, we demonstrate that a highly conserved residue within autotransporter β-barrels is required to position the passenger inside BamA to initiate translocation and that during translocation, the passenger stabilizes the hybrid-barrel state. Our results not only establish a new function for BamA but also unify the divergent functions of BamA and other "Omp85" superfamily transporters.
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http://dx.doi.org/10.1016/j.molcel.2021.02.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8106670PMC
May 2021

Mean maximal power from an on-water 1000-m time-trial predicts lactate threshold power in well-trained flat-water sprint kayak athletes.

Eur J Sport Sci 2021 Feb 21:1-10. Epub 2021 Feb 21.

School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, Australia.

This study utilised on-water graded exercise tests (GXT) to determine the power output (PO) corresponding to the first and second lactate thresholds (LTPO and LTPO), subsequently examining their relationship to the mean maximal power (MMP) and race time achieved across three on-water sprint kayak time-trials. Twelve well-trained sprint kayak athletes completed an on-water GXT and a 200-, 500- and 1000-m time-trial utilising novel instrumented paddle technology. Stepwise multiple regression was used to determine whether equations incorporating 200-, 500- and 1000-m MMP data could be used as an alternative method for estimating LTPO and LTPO. On-water GXT derived LTPO and LTPO were 151 ± 34 and 194 ± 39 W, respectively. For the 200-, 500- and 1000-m time-trials, MMP were 528 ± 143, 358 ± 92 and 287 ± 67 W, respectively. Athletes' LTPO and LTPO had very-large inverse relationships to 200-, 500- and 1000-m time-to-completion ( = -.71 to -.85,  ≤ .010) and very-large, to near-perfect positive relationships to 200-, 500- and 1000-m MMP ( = .81 to .94,  ≤ .001). The equation incorporating 1000-m MMP alone provided the best prediction of LTPO and LTPO, explaining 78% and 88% of the variance, and yielding a standard error of estimate (SEE) of 11.3% and 7.1% for these measures, respectively. The results of this study provide further evidence to support the ecological validity of recently developed on-water GXTs graded by PO, since LTPO and LTPO were significantly correlated to 200-, 500- and 1000-m performance. Practitioners could also predict LTPO with reasonable accuracy based solely from a 1000-m time-trial; potentially providing an alternative, non-invasive, competition-specific protocol for threshold determination. The fact that LT1PO and LT2PO had very-large, to near-perfect positive relationships to 200-, 500- and 1000-m MMP suggests that coaches should consider these relative submaximal aerobic-fitness variables when evaluating the performance of sprint kayak athletes, regardless of their race specialty.While the SEE and 95% limits of agreement (95%LoA) values for the prediction of LTPO may be too large to be practically meaningful, measures of LTPO could be predicted with a reasonable level of accuracy based upon 1000-m MMP.The ability to inform athletes' LTPO from a single 1000-m time-trial is advantageous since it would provide a more feasible, and time-efficient testing protocol within the athletes' training schedule compared to GXTs, potentially allowing coaches and practitioners to monitor changes in LTPO, and subsequently review individual training zones, more regularly.Given that LTPO and LTPO derived from on-water GXTs had very-large, to nearly perfect relationships to 200-, 500- and 1000-m performance, practitioners may prefer to use on-water, rather than laboratory-based GXTs given their greater practical significance and ecological validity.
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http://dx.doi.org/10.1080/17461391.2021.1880648DOI Listing
February 2021

An Outbreak Investigation of Scombrotoxin Fish Poisoning Illnesses in the United States Linked to Yellowfin Tuna Imported from Vietnam-2019.

J Food Prot 2021 Jun;84(6):962-972

U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, Maryland 20740.

Abstract: Scombrotoxin fish poisoning (SFP) is caused by the ingestion of certain fish species with elevated concentrations of histamine due to decomposition. In fall 2019, the U.S. Food and Drug Administration (FDA) was notified of 51 SFP cases including two hospitalizations from 11 states through the FDA consumer complaint system or directly from state partners. A case patient was defined as an individual who experienced a histamine-type reaction after consumption of tuna imported from Vietnam and an illness onset between 14 August and 24 November 2019. A traceback investigation was initiated at 19 points of service to identify a common tuna source. The FDA and state partners collected 34 product samples throughout the distribution chain, including from a case patient's home, points of service, distributors, and the port of entry. Samples were analyzed for histamine by sensory evaluation and/or chemical testing. Case patients reported exposure to tuna imported from Vietnam. The traceback investigation identified two Vietnamese manufacturers as the sources of the tuna. Twenty-nine samples were confirmed as decomposed by sensory evaluation and/or were positive for elevated histamine concentrations by chemical testing. Both Vietnamese companies were placed on an import alert. Seven U.S. companies and one Vietnamese company initiated voluntary recalls. The FDA released public communication naming the U.S. importers to help suppliers and distributors identify the product and effectuate the foreign company's recall. This SFP outbreak investigation highlights the complexities of the federal outbreak response, specifically related to imported food. Cultural considerations regarding imported foods should be addressed during outbreak responses when timing is critical. Collaboration with countries where confidentiality agreements are not in place can limit information sharing and the speed of public health responses.

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http://dx.doi.org/10.4315/JFP-20-456DOI Listing
June 2021

The focal mechanical properties of normal and diseased porcine aortic valve tissue measured by a novel microindentation device.

J Mech Behav Biomed Mater 2021 03 7;115:104245. Epub 2020 Dec 7.

Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada; Translational Biology & Engineering Program, Ted Rogers Centre for Heart Research, Toronto, ON, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada. Electronic address:

Cells sense and respond to the heterogeneous mechanical properties of their tissue microenvironment, with implications for the development of many diseases, including cancer, fibrosis, and aortic valve disease. Characterization of tissue mechanical heterogeneity on cellular length scales of tens of micrometers is thus important for understanding disease mechanobiology. In this study, we developed a low-cost bench-top microindentation system to readily map focal microscale soft tissue mechanical properties. The device was validated by comparison with atomic force microscopy nanoindentation of polyacrylamide gels. To demonstrate its utility, the device was used to measure the focal microscale elastic moduli of normal and diseased porcine aortic valve leaflet tissue. Consistent with previous studies, the fibrosa layer of intact leaflets was found to be 1.91-fold stiffer than the ventricularis layer, with both layers exhibiting significant heterogeneity in focal elastic moduli. For the first time, the microscale compressive moduli of focal proteoglycan-rich lesions in the fibrosa of early diseased porcine aortic valve leaflets were measured and found to be 2.44-fold softer than those of normal tissue. These data provide new insights into the tissue micromechanical environment in valvular disease and demonstrate the utility of the microindentation device for facile measurement of the focal mechanical properties of soft tissues.
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http://dx.doi.org/10.1016/j.jmbbm.2020.104245DOI Listing
March 2021

Competition warm-up strategies in sub-elite and elite flat-water sprint kayak athletes.

J Sports Sci 2021 Jun 9;39(11):1192-1201. Epub 2020 Dec 9.

School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, Australia.

This study compared warm-up strategies employed by sub-elite and world-class elite sprint kayak athletes, evaluating their impact on subsequent race performance. Forty-seven (n = 33 male, n = 14 female) athletes competing at a National Sprint Kayak Championships had Global Navigation Satellite System devices fitted to their kayak to measure speed, distance and stroke rate during the on-water warm-up before racing (OW), and during racing. The OW total duration, average/peak speeds and stroke rates, and the time spent in speed-zones classified based upon athletes' relative race-pace (low-to-moderate, moderate-to-high, and race-specific) were compared between events, sexes, and athlete standard. The relationship of these variables to subsequent race performance, expressed as a percentage of the best time-to-completion for each event (%racebest), was also examined. Women spent greater OW time at moderate-to-high and race-specific speeds compared to men prior to 200-m and 500-m races ( ≤.001). Sub-elite men reported greater total OW duration for 200-m and 500-m ( ≤.025), but not for 1000-m races ( >.05) compared to elite men. Finally, %racebest had large inverse correlations to OW peak speed for men's 200-m (r = -.53), and average stroke rate for women's 500-m races (r = -.50). This study provides valuable insight for competition warm-up routines based upon data from an elite athlete population.
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http://dx.doi.org/10.1080/02640414.2020.1857105DOI Listing
June 2021

Calibration of an Electrical Analog Model of Liver Hemodynamics in Fontan Patients.

J Biomech Eng 2021 03;143(3)

Department of Mechanical and Industrial Engineering, Institute of Biomedical Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.

Fontan associated liver disease is a common complication in patients with Fontan circulation, who were born with a single functioning heart ventricle. The hepatic venous pressure gradient (HVPG) is used to assess liver health and is a surrogate measure of the pressure gradient across the entire liver (portal pressure gradient (PPG)). However, it is thought to be inaccurate in Fontan patients. The main objectives of this study were (1) to apply an existing detailed lumped parameter model (LPM) of the liver to Fontan patients using patient-specific clinical data and (2) to determine whether HVPG is a suitable measurement of PPGs in these patients. An existing LPM of the liver blood circulation was applied and tuned to simulate patient-specific liver hemodynamics. Geometries were collected from seven adult Fontan patients and used to evaluate model parameters. The model was solved and tuned using waveform measurements of flows, inlet and outlet pressures. The predicted ratio of portal to hepatic venous pressures is comparable to in vivo measurements. The results confirmed that HVPG is not suitable for Fontan patients, as it would underestimate the portal pressures gradient by a factor of 3 to 4. Our patient-specific liver model provides an estimate of the pressure drop across the liver, which differs from the clinically used metric HVPG. This work represents a first step toward models suitable to assess liver health in Fontan patients and improve its long-term management.
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http://dx.doi.org/10.1115/1.4049075DOI Listing
March 2021

The Correlation of the Trans-Atlantic Inter-Society Consensus Classification to Outcomes of Pedal Amputations.

J Foot Ankle Surg 2020 Sep - Oct;59(5):1013-1018. Epub 2020 May 28.

Attending Staff and Research Director, Kaiser San Francisco Bay Area Foot and Ankle Residency Program, Kaiser Permanente Oakland Medical Center, Oakland, CA.

In an attempt at limb salvage for patients with peripheral arterial disease, revascularization is often performed prior to pedal amputation. The purpose of this study was to evaluate the association between proximal arterial lesions, based on Trans-Atlantic Inter-Society Consensus aortoiliac, femoropopliteal, and infrapopliteal classifications, and healing pedal amputations post endovascular revascularization. Patients with revascularization up to 90 days prior to pedal amputation with a minimum of 12 months postoperative follow-up were included. Each level of proximal disease was subdivided into Trans-Atlantic Inter-Society Consensus classifications A through D, which range in severity from a single short stenosis or occlusion to more complex stenoses and chronic total occlusion. For comparison, we categorized A and/or B lesions into Group 1 and C and/or D lesions into Group 2. The frequency of proximal lesions was recorded as either isolated, bi-level, or multilevel disease. Chi-square and Fisher's exact tests were used to compare categorical variables. Of the 310 patients, there were a total of 68 aortoiliac, 256 femoropopliteal, and 172 infrapopliteal lesions; 140 patients had isolated lesions, 154 had bi-level disease, and 16 had multilevel disease. Although not statistically significant, patients in Group 1 (A and/or B lesions) had higher proportion of failed amputation compared to Group 2 (C and/or D lesions) in either aortoiliac (84.4% vs 15.6%, p = .17), femoropopliteal (61.2% vs 38.8%, p = .72), or infrapopliteal (57.3% vs 42.7%, p = .44). Bi-level disease showed a higher proportion of failure (50.6%) compared to isolated lesions (43.8%) and multilevel disease (5.6%), (p = .86). To our knowledge, this is the first study to evaluate the association between Trans-Atlantic Inter-Society Consensus arterial lesions and incisional healing of pedal amputations. Despite our belief, there was no correlation between patients with simple, isolated lesions compared to either complex arterial lesions or multilevel disease in healing pedal amputations.
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http://dx.doi.org/10.1053/j.jfas.2020.03.023DOI Listing
June 2021

Heart rate and stroke rate misrepresent supramaximal sprint kayak training as quantified by power.

Eur J Sport Sci 2021 May 14;21(5):656-665. Epub 2020 Jun 14.

School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, Australia.

This study examined the utility of novel measures of power output (PO) compared to traditional measures of heart rate (HR) and stroke rate (SR) for quantifying high-intensity sprint kayak training. Twelve well-trained, male and female sprint kayakers (21.3 ± 6.8 y) completed an on-water graded exercise test (GXT) and a 200-, 500- and 1000-m time-trial for the delineation of individualised training zones (T) for HR (5-zone model, T1-T5), SR and PO (8-zone model, T1-T8). Subsequently, athletes completed two repeat trials of a high-intensity interval (HIIT) and a sprint interval (SIT) training session, where intensity was prescribed using individualised PO-zones. Time-in-zone (minutes) using PO, SR and HR was then compared for both HIIT and SIT. Compared to PO, time-in-zone using HR was higher for T1 in HIIT and SIT ( < 0.001, ≥ 0.90) and lower for T5 in HIIT ( < 0.001,  = 1.76). Average and peak HR were not different between HIIT (160 ± 9 and 173 ± 11 bpm, respectively) and SIT (157 ± 13 and 174 ± 10 bpm, respectively) (≥ 0.274). In HIIT, time-in-zone using SR was higher for T4 ( < 0.001,  = 0.85) and was lower for T5 ( = 0.005,  = 0.43) and T6 ( < 0.001,  = 0.94) compared to PO. In SIT, time-in-zone using SR was lower for T7 ( = 0.001,  = 0.66) and was higher for T8 ( = 0.004,  = 0.70), compared to PO. Heart rate measures were unable to differentiate training demands across different high-intensity sessions, and could therefore misrepresent the training load in such instances. Furthermore, SR may not provide a sensitive measure for detecting changes in intensity due to fatigue, whereas PO may be more suitable.
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http://dx.doi.org/10.1080/17461391.2020.1771430DOI Listing
May 2021

Cardiovascular and abdominal flow alterations in adults with morphologic evidence of liver disease post Fontan palliation.

Int J Cardiol 2020 Oct 27;317:63-69. Epub 2020 May 27.

Joint Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Canada; Division of Cardiology, Peter Munk Cardiac Centre, University Health Network, University of Toronto, Toronto, Canada; Division of Pediatric Cardiology, Hospital for Sick Children, University of Toronto, Toronto, Canada. Electronic address:

Background: Although morphologic abnormalities in the liver are commonly encountered post Fontan palliation, the relationships between hepatic morphology, vascular flows, and clinical status remain incompletely understood. We therefore aimed to explore flow characteristics in hepatic and intestinal vessels and to examine cardiovascular associations with liver disease.

Methods: This was a retrospective study of adults post Fontan palliation undergoing clinically indicated cardiovascular magnetic resonance imaging (MRI). Patients were included if MRI flow quantification was available for cardiac, hepatic and intestinal vessels; patients were excluded if phase-contrast flow imaging was insufficient for analysis.

Results: Thirty patients were studied (median age at MRI 28.5 years [range 19-47]). Eighteen subjects (60%) were classified as having morphologic liver disease according to validated criteria based on available MRI imaging. Abdominal and cardiovascular flows were quantified. Patients with morphologic liver disease had a 41% reduction in superior mesenteric artery (211 ± 124 versus 358 ± 181 mL/min/m, p = .004), a 36% reduction in hepatic vein (496 ± 247 versus 778 ± 220 mL/min/m, p = .01), a 31% reduction in portal vein (399 ± 133 versus 580 ± 159 mL/min/m, p = .004), and an 18% reduction in Fontan pathway flows (1358 ± 429 versus 1651 ± 270 mL/min/m, p = .04) compared with the remaining population. Adverse cardiovascular events were not associated with morphologic liver disease.

Conclusion: Morphologic liver disease appears to be associated with flow alterations within the heart, liver and intestine post Fontan palliation. These novel observations suggest that a potential relationship exists between morphologic disease and vascular flows thereby providing further insights into the pathophysiology of liver disease in this high-risk population.
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http://dx.doi.org/10.1016/j.ijcard.2020.05.064DOI Listing
October 2020

The Effects of Endovascular Timing and In-line Flow on the Success of Pedal Amputations.

J Foot Ankle Surg 2020 Sep - Oct;59(5):964-968. Epub 2020 May 12.

Attending Staff and Research Director, Kaiser San Francisco Bay Area Foot and Ankle Residency Program, Kaiser Permanente Oakland Medical Center, Oakland, CA.

There has been a growing trend toward endovascular intervention to improve peripheral flow in patients with peripheral arterial disease. To date, there is no clear consensus regarding timing of lower-extremity amputations after revascularization. The purpose of this study was to evaluate the effects of timing between endovascular intervention and minor lower-extremity amputations and its influence on wound healing and limb loss within 1 year. A secondary purpose was to evaluate the impact of restoring in-line flow on healing rates. A total of 310 patients who underwent endovascular intervention and a minor lower-extremity amputation within 90 days were included in the study. Healing rates were defined as optimal, delayed, or failure. There was a statistically significant difference between patients with optimal healing to delayed healing and amputation ≥30 days after endovascular intervention (p = .037). We found no difference in healing rates in regard to amputation timing when examining patients who ultimately healed versus patients who failed to heal (p = .6717). Absence of in-line flow (p = .0177), male sex (p = .0090) and diabetes mellitus (p = .0076) were statistically significant factors for failing to heal. Presence of infection (p ≤ .0001) and wound dehiscence (p ≤ .001) were also associated with a failure to heal. End-stage renal disease trended toward significance for failing to heal (p = .065). Amputation-free survival at 1 year after endovascular intervention and pedal amputation was 76.8% (n = 238). Our findings suggest that in the absence of infection, performing minor lower-extremity amputations 15 to 60 days after endovascular intervention may allow for improved healing. Absence of in-line flow, male sex, diabetes mellitus, postoperative infection, and wound dehiscence are significant factors for failure.
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http://dx.doi.org/10.1053/j.jfas.2020.03.018DOI Listing
June 2021

Microorganisms Associated With Osteomyelitis of the Foot and Ankle.

J Foot Ankle Surg 2020 May - Jun;59(3):491-494

Attending Staff, Kaiser San Francisco Bay Area Foot and Ankle Residency Program, Kaiser Oakland Medical Center, Oakland, CA.

Osteomyelitis of the foot and ankle is a challenge to treat and creates a significant demand on both the patient and the healthcare system. The purposes of this study were to determine the microorganisms associated with foot and ankle osteomyelitis, to evaluate the change in methicillin-resistant Staphylococcus aureus (MRSA) between 2005 and 2010, and to determine the relationship between these infecting organisms and patient comorbidities. The medical records for 302 patients diagnosed with osteomyelitis of the foot and ankle, 151 in 2005 and 151 in 2010, were randomly selected and evaluated. The authors reviewed the demographics, comorbidities, microorganism(s) confirmed with bone biopsy and culture, location, and use of antibiotics before bone biopsy. Gram-positive bacteria were the most prevalent, composing 81.9% of the isolates in 2005 and 59.6% in 2010. Methicillin-sensitive Staphylococcus aureus was the most common in both cohorts. Conversely, the incidence of MRSA statistically decreased from 28.3% to 10.6% from 2005 to 2010 (p < .0001). Gram-negative bacteria were found in 39.5% of the 2005 isolates and 31.8% of those from 2010. Pseudomonas sp. was the most common gram-negative bacteria. Patients with peripheral vascular disease had a significantly higher incidence of gram-negative bacteria (odds ratio 2.1, 95% confidence interval, 1.3 to 3.6, p = .003). The results of this study reveal that MSSA was the most common bacteria, incidence of MRSA decreased between the 2005 to 2010, and patients with peripheral vascular disease have a significantly higher incidence of gram-negative bacteria.
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http://dx.doi.org/10.1053/j.jfas.2019.08.032DOI Listing
April 2021

Early Protected Weightbearing After Open Reduction Internal Fixation of Ankle Fractures With Trans-syndesmotic Screws.

J Foot Ankle Surg 2020 Jul - Aug;59(4):726-728. Epub 2020 Feb 11.

Attending Staff, Kaiser San Francisco Bay Area Foot and Ankle Residency Program, Department of Orthopedics, Kaiser Foundation Hospital, San Francisco, CA. Electronic address:

Traditional postoperative care after open reduction internal fixation (ORIF) of unstable ankle fractures with syndesmotic instability includes non-weightbearing for 6 to 8 weeks. However, prolonged non-weightbearing may be detrimental. The goal of this case series was to assess the outcomes of early protected weightbearing after operative treatment of acute ankle fractures with syndesmotic instability requiring screw stabilization. Fifty-eight consecutive patients, treated from January 2006 to January 2013, met the inclusion criteria with a minimum follow up of 1 year. Electronic medical records and radiographs were reviewed for patient and surgical characteristics, postoperative complications, and maintenance of reduction. Patients initiated walking at an average of 10 days (range 1 to 15) postoperatively. Surgical treatment consisted of operative reduction with standard fixation devices and 1 or 2 trans-syndesmotic screws that purchased 4 cortices. All 58 patients maintained correction after surgery when allowed to weightbear early in the postoperative recovery. Five complications (8.6%) occurred in the 58 patients, which included 3 superficial infections (5.2%) and 2 cases (3.4%) of neuritis. The maintenance of reduction and low complication rate in this study support the option of early protected weightbearing after ankle fracture ORIF with trans-syndesmotic fixation.
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http://dx.doi.org/10.1053/j.jfas.2020.01.003DOI Listing
June 2021

The virulence domain of Shigella IcsA contains a subregion with specific host cell adhesion function.

PLoS One 2020 7;15(1):e0227425. Epub 2020 Jan 7.

School of Biological Sciences, Department of Molecular & Biomedical Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia.

Shigella species cause bacillary dysentery, especially among young individuals. Shigellae target the human colon for invasion; however, the initial adhesion mechanism is poorly understood. The Shigella surface protein IcsA, in addition to its role in actin-based motility, acts as a host cell adhesin through unknown mechanism(s). Here we confirmed the role of IcsA in cell adhesion and defined the region required for IcsA adhesin activity. Purified IcsA passenger domain was able block S. flexneri adherence and was also used as a molecular probe that recognised multiple components from host cells. The region within IcsA's functional passenger domain (aa 138-148) was identified by mutagenesis. Upon the deletion of this region, the purified IcsAΔ138-148 was found to no longer block S. flexneri adherence and had reduced ability to interact with host molecules. Furthermore, S. flexneri expressing IcsAΔ138-148 was found to be significantly defective in both cell adherence and invasion. Taken together, our data identify an adherence region within the IcsA functional domain and provides useful information for designing therapeutics for Shigella infection.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0227425PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6946128PMC
April 2020

Interoperability and Considerations for Standards-Based Exchange of Medical Images: HIMSS-SIIM Collaborative White Paper.

J Digit Imaging 2020 02;33(1):6-16

Research and Development, Epic, Madison, WI, USA.

This white paper explores the considerations of standards-based interoperability of medical images between organizations, patients, and providers. In this paper, we will look at three different standards-based image exchange implementations that have been deployed to facilitate exchange of images between provider organizations. The paper will describe how each implementation uses applicable technology and standards; the image types that are included; and the governance policies that define participation, access, and trust. Limitations of the solution or non-standard approaches to solve challenges will also be identified. Much can be learned from successes elsewhere, and those learnings will point to recommendations of best practices to facilitate the adoption of image exchange.
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http://dx.doi.org/10.1007/s10278-019-00294-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064628PMC
February 2020

Comparison of Training Monitoring and Prescription Methods in Sprint Kayaking.

Int J Sports Physiol Perform 2020 05 1;15(5):654-662. Epub 2020 May 1.

Purpose: To compare methods of monitoring and prescribing on-water exercise intensity (heart rate [HR], stroke rate [SR], and power output [PO]) during sprint kayak training.

Methods: Twelve well-trained flat-water sprint kayak athletes completed a preliminary on-water 7 × 4-min graded exercise test and a 1000-m time trial to delineate individual training zones for PO, HR, and SR into a 5-zone model (T1-T5). Subsequently, athletes completed 2 repeated trials of an on-water training session, where intensity was prescribed based on individual PO zones. Times quantified for T1-T5 during the training session were then compared between PO, HR, and SR.

Results: Total time spent in T1 was higher for HR (P < .01) compared with PO. Time spent in T2 was lower for HR (P < .001) and SR (P < .001) compared with PO. Time spent in T3 was not different between PO, SR, and HR (P > .05). Time spent in T4 was higher for HR (P < .001) and SR (P < .001) compared with PO. Time spent in T5 was higher for SR (P = .03) compared with PO. Differences were found between the prescribed and actual time spent in T1-T5 when using PO (P < .001).

Conclusions: The measures of HR and SR misrepresented time quantified for T1-T5 as prescribed by PO. The stochastic nature of PO during on-water training may explain the discrepancies between prescribed and actual time quantified for power across these zones. For optimized prescription and monitoring of athlete training loads, coaches should consider the discrepancies between different measures of intensity and how they may influence intensity distribution.
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http://dx.doi.org/10.1123/ijspp.2019-0190DOI Listing
May 2020

Commentary: Engineering an optimal mechanical circulatory support system for the cavopulmonary connection.

J Thorac Cardiovasc Surg 2020 02 20;159(2):e143-e144. Epub 2019 Aug 20.

Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.

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http://dx.doi.org/10.1016/j.jtcvs.2019.08.001DOI Listing
February 2020

Impact of Insertion Technique and Iliac Artery Anatomy on Fenestrated Endovascular Aneurysm Repair.

J Endovasc Ther 2019 12 28;26(6):797-804. Epub 2019 Aug 28.

Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada.

To develop a mechanically realistic aortoiliac model to evaluate anatomic variables associated with stent-graft rotation and to assess common deployment techniques that may contribute to rotation. Idealized aortoiliac geometries were constructed either through direct 3-dimensional (3D) printing (rigid) or through casting with polyvinyl alcohol using 3D-printed molds (flexible). Flexible model bending rigidity was controlled by altering wall thickness. Three flexible patient-specific models were also created based on the preoperative computed tomography angiograms. Zenith infrarenal and fenestrated devices were used in this study. The models were pressurized to 100 mm Hg with normal saline. Deployments were performed under fluoroscopy at 37°C. Rotation was calculated by tracking the change in position of gold markers affixed to the devices. In the rigid idealized models, stent-graft rotation increased with increasing torsion; torsion levels of 1.6, 2.6, and 3.6 mm had mean rotations of 5.2°±0.03°, 11.2°±4.8°, and 27.6°±13.0°, respectively (p<0.001). In the flexible models, the highest rotation (58°±3.0°) was observed in models with high torsion and high rigidity (7.5 mm net torsion and 254 N·m flexural rigidity). No rotation was observed in the absence of torsion. Applying torque to the device during insertion significantly increased stent-graft rotation by an average of 28° across all levels of torsion (p<0.01). Multiple device insertions prior to deployment did not change the observed device rotation. The patient-specific models accurately predicted the degree of rotation seen intraoperatively to within 5°. Insertion technique plays an important role in the degree of stent-graft rotation during deployment. Our model suggests that in vivo correction of device orientation can increase the observed rotation and supports the concept of fully removing the device, adjusting the orientation, and subsequently reinserting. Additionally, increasing iliac artery torsion in the presence of increased vessel rigidity results in stent-graft rotation.
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http://dx.doi.org/10.1177/1526602819872499DOI Listing
December 2019

Bacterial outer membrane proteins assemble via asymmetric interactions with the BamA β-barrel.

Nat Commun 2019 07 26;10(1):3358. Epub 2019 Jul 26.

Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.

The integration of β-barrel proteins into the bacterial outer membrane (OM) is catalysed by the β-barrel assembly machinery (BAM). The central BAM subunit (BamA) itself contains a β-barrel domain that is essential for OM protein biogenesis, but its mechanism of action is unknown. To elucidate its function, here we develop a method to trap a native Escherichia coli β-barrel protein bound stably to BamA at a late stage of assembly in vivo. Using disulfide-bond crosslinking, we find that the first β-strand of a laterally 'open' form of the BamA β-barrel forms a rigid interface with the C-terminal β-strand of the substrate. In contrast, the lipid-facing surface of the last two BamA β-strands forms weaker, conformationally heterogeneous interactions with the first β-strand of the substrate that likely represent intermediate assembly states. Based on our results, we propose that BamA promotes the membrane integration of partially folded β-barrels by a 'swing' mechanism.
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http://dx.doi.org/10.1038/s41467-019-11230-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6659671PMC
July 2019

Comparison of Qualitative and Quantitative Assessments of Iliac Artery Tortuosity and Calcification.

Vasc Endovascular Surg 2019 Aug 18;53(6):464-469. Epub 2019 Jun 18.

2 Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network and University of Toronto, Toronto, Canada.

Introduction: During endovascular aneurysm repair, the iliac artery typically serves as a conduit for device delivery. The degree of tortuosity and calcification in the iliac artery ultimately determines whether the device can successfully traverse the vessel. These 2 parameters can be assessed using qualitative approaches or calculated using quantitative methods based on the Society for Vascular Surgery (SVS) reporting standards. The objective of this study was to determine whether qualitative methods are sufficient to accurately assess iliac artery tortuosity and calcification by calculating interobserver variability and comparing them to the SVS Reporting Standards.

Methods: Three vascular surgeons reviewed preoperative computed tomography scans for 50 patients who underwent fenestrated endovascular aneurysm repair and qualitatively assessed left and right iliac artery tortuosity and calcification. Iliac artery geometries were segmented from these image sets. Tortuosity index and calcification length ratio were calculated and categorized based on the SVS Reporting Standards.

Results: Interobserver variability was calculated for the qualitative assessments using interclass correlation coefficients. For tortuosity index, among the 3 observers, good agreement was found for the left iliac artery and fair agreement was found for the right. For calcification length ratio, excellent agreement was found for both iliac arteries. When compared to the quantitative assessment, the qualitative assessments underpredicted tortuosity in 2.3% of cases, matched the quantitative values in 16.7% of cases, and overpredicted tortuosity in 81.0% of cases. The qualitative assessments underpredicted calcification in 46.3% of cases, matched the quantitative values in 49.3% of cases, and overpredicted calcification in 4.3% of cases.

Conclusion: Qualitative assessment of iliac artery tortuosity showed fair-to-good interobserver agreement and poor agreement to SVS Reporting Standards. Qualitative assessment of iliac artery calcification showed excellent interobserver agreement and fair agreement to SVS Reporting Standards. These trends should be considered when qualitative reporting methodologies are used.
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http://dx.doi.org/10.1177/1538574419858163DOI Listing
August 2019

Computational fluid dynamic simulations of a cavopulmonary assist device for failing Fontan circulation.

J Thorac Cardiovasc Surg 2019 11 21;158(5):1424-1433.e5. Epub 2019 Mar 21.

Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.

Objectives: Adult patients who have undergone the Fontan procedure are highly vulnerable to gradual, progressive circulatory failure, and options to reverse this situation are few. A cavopulmonary assist device could decongest the venous and lymphatic systems, overcome elevated pulmonary vascular resistance, increase cardiac output, and support some of these patients to heart transplant. This study characterizes the performance and challenges of a novel multilumen cannula coupled to an external blood pump proposed as a potential Fontan cavopulmonary assist strategy.

Methods: Computational fluid dynamic simulations were conducted for 3 extracardiac Fontan geometries consisting of 1 idealized model and 2 patient-specific models. A range of physiologic flow rates and pump assist levels were simulated to calculate the pressure gain provided by the multilumen cannula. Hemolysis index was estimated for the idealized model with Lagrangian particle tracking and 2 variations of the power-law. Wall shear stresses were also examined.

Results: Pressure gains up to 4 and 9 mm Hg were achieved for the idealized and patient-specific models, respectively. Pressure gains increased with both higher cardiac output and larger pump intake through the external pump. Flow-weighted hemolysis show hemoglobin damage levels to be several times lower than the 2% threshold at the highest pump intake flow cases. Wall shear stress predictions depict elevated areas in the pulmonary vessels and regions of the cannula device.

Conclusions: The cannula tested in this study shows promise as a percutaneous option to bridge support in some patients with a failing extracardiac Fontan. Limitations identified will be addressed in future design iterations and in ongoing experimental tests.
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http://dx.doi.org/10.1016/j.jtcvs.2019.03.008DOI Listing
November 2019

Impact of fenestrated stent graft misalignment on patient outcomes.

J Vasc Surg 2019 10 27;70(4):1056-1064. Epub 2019 Mar 27.

Division of Vascular Surgery, University Health Network, Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada. Electronic address:

Objective: During fenestrated endovascular aneurysm repair (FEVAR), accurate alignment of the fenestration and the target artery is necessary to prevent complications. This study's objective is to determine the incidence of clinical outcomes following fenestration misalignment during FEVAR.

Methods: A single-center, retrospective chart review was performed for all elective FEVARs between January 2008 and April 2015. Data were gathered from patient records and intraoperative imaging. Native vessel angles were calculated using the vessel centerlines. Intraoperative stent graft orientation was determined by changing the angle of the image intensifier as the fenestration was profiled for cannulation. Vertical fenestration misalignment was defined as 4 mm or greater and is the distance from the center of the fenestration markers to the center of the target vessel ostium at the time of cannulation. Horizontal stent graft misalignment was defined as a difference between the native vessel angle and the intraoperative fenestration angle of 15° or more. Early and late clinical outcomes were analyzed with respect to the presence of either vertical or horizontal misalignment of the renal artery fenestrations.

Results: The study cohort includes 65 patients who underwent FEVAR during this study period. A horizontal misalignment of 15° or more occurred in 40% of patients (n = 26) and 30° or more in 9.2% of patients (n = 6). A vertical misalignment of 4 mm or greater occurred in 32.3% of patients (n = 21). The incidence of severe postoperative complications, defined as any in-hospital end-organ ischemia and/or death, was significantly greater for patients with stent graft misalignment-31% (n = 11) vs 3% (n = 1) in the aligned group. There was a trend toward higher rates of target vessel cannulation failure in patients with stent graft misalignment 3% (n = 99 fenestrations) vs 0% (n = 76 fenestrations). The combined incidence of any intraoperative target vessel complication was significantly higher in patients with misalignment, 8.1% (4, 15) vs 1.3% (0, 8). Long-term survival was significantly lower in patients with stent graft misalignment, which was primarily driven by high intraoperative and in-hospital mortality rates (P < .05).

Conclusions: Intraoperative stent graft misalignment is associated with higher rates of procedural target vessel complications and severe postoperative adverse events. Patients with stent graft misalignment should be considered at high risk for early postoperative complications. These results highlight an important need for improved FEVAR planning.
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http://dx.doi.org/10.1016/j.jvs.2018.12.047DOI Listing
October 2019

Demographic Profile of Chiropractors Who Treat Children: A Multinational Survey.

J Manipulative Physiol Ther 2019 01 20;42(1):1-11. Epub 2019 Mar 20.

Anglo-European College of Chiropractic, Bournemouth University, United Kingdom.

Objective: The purpose of this study was to survey the demographic profile and educational background of chiropractors with pediatric patients on a multinational scale.

Methods: A multinational online cross-sectional demographic survey conducted over a 15-day period in July 2010. The survey was electronically administered via chiropractic associations in 17 countries, using SurveyMonkey for data acquisition, transfer, and descriptive analysis.

Results: The response rate was 10.1%, and 1498 responses were received from 17 countries on 6 continents. Of these, 90.4% accepted pediatric cases. The average practitioner was male (61.1%) and 41.4 years old, had 13.6 years in practice, and saw 107 patient visits per week. Regarding educational background, 63.4% had a bachelor's degree or higher in addition to their chiropractic qualification, and 18.4% had a postgraduate certificate or higher in pediatric chiropractic.

Conclusion: This is the first study about chiropractors who treat children from the United Arab Emirates, Peru, Japan, South Africa, and Spain. Although the response rate was low, the results of this multinational survey suggest that pediatric chiropractic care may be a common component of usual chiropractic practice on a multinational level for these respondents.
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http://dx.doi.org/10.1016/j.jmpt.2018.03.007DOI Listing
January 2019

Development of an On-Water Graded Exercise Test for Flat-Water Sprint Kayak Athletes.

Int J Sports Physiol Perform 2019 Aug 26:1244-1249. Epub 2019 Aug 26.

Purpose: To determine the reliability and validity of a power-prescribed on-water (OW) graded exercise test (GXT) for flat-water sprint kayak athletes.

Methods: Nine well-trained sprint kayak athletes performed 3 GXTs in a repeated-measures design. The initial GXT was performed on a stationary kayak ergometer in the laboratory (LAB). The subsequent 2 GXTs were performed OW (OW1 and OW2) in an individual kayak. Power output (PWR), stroke rate, blood lactate, heart rate, oxygen consumption, and rating of perceived exertion were measured throughout each test.

Results: Both PWR and oxygen consumption showed excellent test-retest reliability between OW1 and OW2 for all 7 stages (intraclass correlation coefficient > .90). The mean results from the 2 OW GXTs (OWAVE) were then compared with LAB, and no differences in oxygen consumption across stages were evident (P ≥ .159). PWR was higher for OWAVE than for LAB in all stages (P ≤ .021) except stage 7 (P = .070). Conversely, stroke rate was lower for OWAVE than for LAB in all stages (P < .010) except stage 2 (P = .120).

Conclusions: The OW GXT appears to be a reliable test in well-trained sprint kayak athletes. Given the differences in PWR and stroke rate between the LAB and OW tests, an OW GXT may provide more specific outcomes for OW training.
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http://dx.doi.org/10.1123/ijspp.2018-0717DOI Listing
August 2019

Predicting Rotation in Fenestrated Endovascular Aneurysm Repair Using Finite Element Analysis.

J Biomech Eng 2018 09;140(9)

Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON M5S 3G8, Canada.

Fenestrated endovascular aneurysm repair (FEVAR) is a minimally invasive method of abdominal aortic aneurysm (AAA) repair utilized in patients with complex vessel anatomies. Stent grafts (SG) used in this process contain fenestrations within the device that need to be aligned with the visceral arteries upon successful SG deployment. Proper alignment is crucial to maintain blood flow to these arteries and avoid surgical complications. During fenestrated SG deployment, rotation of the SG can occur during the unsheathing process. This leads to misalignment of the vessels, and the fenestrations and is associated with poor clinical outcomes. The aim of this study was to develop a computational model of the FEVAR process to predict SG rotation. Six patient-specific cases are presented and compared with surgical case data. Realistic material properties, frictional effects, deployment methods, and boundary conditions are included in the model. A mean simulation error of 2 deg (range 1-4 deg) was observed. This model was then used to conduct a parameter study of frictional properties to see if rotation could be minimized. This study showed that increasing or decreasing the coefficients of friction (COF) between the sheath and the vessel walls would decrease the amount of rotation observed. Our model accurately predicts the amount of SG rotation observed during FEVAR and can be used as a preoperative planning tool within the surgical workflow.
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http://dx.doi.org/10.1115/1.4040124DOI Listing
September 2018

Microdevice arrays with strain sensors for 3D mechanical stimulation and monitoring of engineered tissues.

Biomaterials 2018 07 23;172:30-40. Epub 2018 Apr 23.

Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, M5S 3G9, Canada; Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, Toronto, M5G 1M1, Canada. Electronic address:

Native and engineered tissue development are regulated by the integrative effects of multiple microenvironmental stimuli. Microfabricated bioreactor array platforms can efficiently dissect cue-response networks, and have recently integrated critical 2D and 3D mechanical stimulation for greater physiological relevance. However, a limitation of these approaches is that assessment of tissue functional properties is typically limited to end-point analyses. Here we report a new deformable membrane platform with integrated strain sensors that enables mechanical stretching or compression of 3D cell-hydrogel arrays and simultaneous measurement of hydrogel construct stiffness in situ. We tested the ability of the integrated strain sensors to measure the evolution of the stiffness of cell-hydrogel constructs for two cases. First, we demonstrated in situ stiffness monitoring of degradable poly (ethylene glycol)-norbornene (PEG-NB) hydrogels embedded with mesenchymal stromal cells (MSCs) and cultured with or without cyclic tensile stimulation for up to 15 days. Whereas statically-cultured hydrogels degraded and softened throughout the culture period, mechanically-stimulated gels initially softened and then recovered their stiffness corresponding to extensive cell network and collagen production. Second, we demonstrated in situ measurement of compressive stiffening of MSC-seeded PEG-NB gels cultured statically under osteogenic conditions, corresponding to increased mineralization and cellularization. This measurement technique can be generalized to other relevant bioreactor and organ-on-a-chip platforms to facilitate online, non-invasive, and high-throughput functional analysis, and to provide insights into the dynamics of engineered tissue development that are otherwise not available.
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http://dx.doi.org/10.1016/j.biomaterials.2018.04.041DOI Listing
July 2018

Arthroscopic-Assisted Open Reduction Internal Fixation.

Clin Podiatr Med Surg 2018 Apr 2;35(2):199-221. Epub 2018 Jan 2.

Department of Orthopedics, Kaiser San Francisco Bay Area Foot and Ankle Residency Program, Kaiser Permanente Oakland Medical Center, 275 West MacArthur Boulevard, Oakland, CA 94611, USA; Department of Podiatry, Kaiser San Francisco Bay Area Foot and Ankle Residency Program, Kaiser Permanente Oakland Medical Center, 275 West MacArthur Boulevard, Oakland, CA 94611, USA.

The indications for arthroscopy have expanded over the years. Arthroscopic-assisted open reduction internal fixation in the setting of acute trauma is gaining popularity with foot and ankle surgeons. It serves to facilitate direct visualization of fracture fragments and allows for precise articular reduction with minimal soft tissue insult. Current evidence reports a high incidence of chondral injury with ankle fractures. Arthroscopy performed at the time of open reduction internal fixation allows for joint inspection and potential treatment of these posttraumatic defects.
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http://dx.doi.org/10.1016/j.cpm.2017.12.004DOI Listing
April 2018

Analysis of Iliac Artery Geometric Properties in Fenestrated Aortic Stent Graft Rotation.

Vasc Endovascular Surg 2018 Apr 7;52(3):188-194. Epub 2018 Feb 7.

2 Division of Vascular Surgery, Department of Surgery, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada.

Introduction: A complication of fenestrated endovascular aneurysm repair is the potential for stent graft rotation during deployment causing fenestration misalignment and branch artery occlusion. The objective of this study is to demonstrate that this rotation is caused by a buildup of rotational energy as the device is delivered through the iliac arteries and to quantify iliac artery geometric properties associated with device rotation.

Methods: A retrospective clinical study was undertaken in which iliac artery geometric properties were assessed from preoperative imaging for 42 cases divided into 2 groups: 27 in the nonrotation group and 15 in the rotation group. Preoperative computed tomography scans were segmented, and the iliac artery centerlines were determined. Iliac artery tortuosity, curvature, torsion, and diameter were calculated from the centerline and the segmented vessel geometry.

Results: The total iliac artery net torsion was found to be higher in the rotation group compared to the nonrotation group (23.5 ± 14.7 vs 14.6 ± 12.8 mm; P = .05). No statistically significant differences were found for the mean values of tortuosity, curvature, torsion, or diameter between the 2 groups.

Conclusion: Stent graft rotation occurred in 36% of the cases considered in this study. Cases with high iliac artery total net torsion were found to be more likely to have stent graft rotation upon deployment. This retrospective study provides a framework for prospectively studying the influence of iliac artery geometric properties on fenestrated stent graft rotation.
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http://dx.doi.org/10.1177/1538574418754989DOI Listing
April 2018
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