Efficient Post-processing of Diffusion Tensor Cardiac Magnetic Imaging Using Texture-conserving Deformable Registration

Diffusion tensor based cardiac magnetic resonance (DT-CMR) is a method capable of providing non-invasive measurements of myocardial microstructure. Image registration is essential to correct image shifts due to intra and inter breath-hold motion. Registration is challenging in DT-CMR due to the low signal-to-noise and various contrasts induced by the diffusion encoding in the myocardial and surrounding organs. Traditional deformable registration destroys the texture information while rigid registration inefficiently discards frames with local deformation. In this study, we explored the possibility of deep learning-based deformable registration on DT- CMR. Based on the noise suppression using low-rank features and diffusion encoding suppression using variational auto encoder-decoder, a B-spline based registration network extracted the displacement fields and maintained the texture features of DT-CMR. In this way, our method improved the efficiency of frame utilization, manual cropping, and computational speed.Comment: 4 pages, 4 figures, conferenc

Sexual Dimorphism: increased sterol excretion leads to hypocholesterolaemia in female hyperbilirubinaemic Gunn rats

KEY POINTS: Female adult hyperbilirubinaemic (Gunn) rats demonstrated lower circulating cholesterol corroborating human studies that report a negative association between bilirubin and cholesterol concentrations. Furthermore, female Gunn rats had elevated sterol excretion creating a negative intestinal sterol balance that was compensated for by elevated cholesterol synthesis and increased hepatic LDL receptor expression. Therefore, elevated LDL receptor expression potentially leads to reduced circulating cholesterol levels in female Gunn rats providing an explanation for the hypocholesterolaemia observed in humans with elevated bilirubin levels. This study also reports a novel interaction of sex with the hyperbilirubinaemic phenotype on sterol metabolism because changes were only reported in females and not in male Gunn rats. Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome). ABSTRACT: Background Circulating bilirubin is associated with reduced serum cholesterol concentrations in humans and in hyperbilirubinaemic Gunn rats. However, mechanisms contributing to hypocholesterolaemia remain unknown. Therefore, this study aimed to investigate cholesterol synthesis, transport, and excretion in mutant Gunn rats. Methods Adult Gunn and control rats were assessed for daily faecal sterol excretion using metabolic cages and water was supplemented with [1-13 C]-acetate to determine cholesterol synthesis. Bile was collected to measure biliary lipid secretion. Serum and liver were collected for biochemical analysis and for gene/protein expression using RT-qPCR and western blot, respectively. Additionally, serum was collected and analysed from juvenile rats. Results A significant interaction of sex, age, and phenotype on circulating lipids was found with adult female Gunn rats reporting significantly lower cholesterol and phospholipids. Female Gunn rats also demonstrated elevated cholesterol synthesis, greater biliary lipid secretion, and increased total faecal cholesterol and bile acid excretion. Furthermore, they possessed increased hepatic LDL receptor and SREBP2 expression. In contrast, there was no changes to sterol metabolism in adult male Gunn rats. Conclusions This is the first study to demonstrate elevated faecal sterol excretion in female hyperbilirubinaemic Gunn rats. Increased sterol excretion creates a negative intestinal sterol balance that is compensated for by increased cholesterol synthesis and LDL receptor expression. Therefore, reduced circulating cholesterol is potentially caused by increased hepatic uptake via the LDL receptor. Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome). Abstract figure legend This article is protected by copyright. All rights reserved

The effects of acute beetroot juice ingestion on upper and lower body muscular power during weightlifting exercise in men

Nitrate-rich beetroot juice (BR) supplementation improves movements with high-velocity and high-power muscle contractions which may be due to enhanced blood flow, oxygenation and contractile function in type II muscle fibers. The literature has focused predominantly on the effects of BR supplementation running and cycling performance, but its efficacy in resistance exercise, a modality that relies on type II muscle fibers, has limited data. Furthermore, it is unknown how supplementation strategies impact the physiological and ergogenic effects of BR during exercise. Therefore, the purpose of this study is to assess whether single or multi-day nitrate ingestion will improve performance and muscle oxygenation during resistance exercise. In a double-blind, randomized crossover design, 14 healthy recreationally active men will report to the laboratory for five occasions over a 4-wk period. On the first visit, participants will undergo a 1 repetition-max (1RM) test for back squat and bench press. Subsequently, participants will complete two 4-day experimental trials where they will consume 2 x 70mL doses per day of either nitrate-depleted placebo (PL) or concentrated nitrate-rich BR. On experimental days of each supplementation period (day 1 and 4), subjects will consume 140 mL of their allocated beverage 2.5-h before exercise. On day 2 and 3 of the supplementation period, participants will consume one 70 mL beverage in the morning and one in the evening. On experimental days, participants performed a power protocol, consisting of 2 sets x 2 repetitions of back squats and bench press at 70%1RM followed by repetition-to-failures at 60%1RM. Muscle oxygenation, power and velocity were assessed during exercise using near infrared spectroscopy and a linear transducer, respectively. A subset of data has been collected (n=9) and data collection is ongoing

The effects of acute beetroot juice ingestion on upper and lower body muscular power during weightlifting exercise in men.

Dietary nitrate supplementation, administered per beetroot juice (BR), has been shown to enhance performance while cycling and running. BR has enhanced skeletal muscle contraction and blood flow within type II fibers which are recruited during high-velocity and high-power contractions. However, it is unknown whether BR influences alternative forms of exercise, such as resistance exercise. The purpose of this study is to assess whether BR supplementation influences neuromuscular performance (muscle power and speed), and repetitions-to-failure in healthy, recreationally active men. In a double-blind, randomized crossover design, 14 males will be recruited to complete two 4-day supplementation periods in which they consume 2 x 70mL nitrate-depleted placebo (PL) or nitrate-rich BR per day. Subjects will report to the lab 5 times over a 3-to 4-wk period. Subjects will complete a 1 repetition max (1RM) test and familiarization to the protocol. On experimental days subjects will complete a warm up and then a protocol to assess explosive performance, consisting of 2 sets x 2 repetitions of back squat at 70% 1RM using a cadence that emphasizes an explosive concentric phase. Skeletal muscle oxygenation will be measured using near-infrared spectroscopy and neuromuscular performance will be measured during exercise using a linear transducer. Following a 5-min recovery period, subjects performed 1 set x repetition-to-failure at 60% 1RM to determine muscular endurance. This protocol will be repeated in the bench press exercise. Data was analyzed in a subset of n = 9. There were no significant differences in resistance exercise performance between conditions; however, data collection is ongoing and results are currently underpowered. These data could provide insight for dietary nitrate as an ergogenic aid and inform both supplementation guidelines and recommendations for enhancing resistance training performance in men