Geometrical models for cardiac MRI in rodents: comparison of quantification of left ventricular volumes and function by various geometrical models with a full-volume MRI data set in rodents.

van de Weijer T, van Ewijk PA, Zandbergen HR, Slenter JM, Kessels AG, Wildberger JE, Hesselink MK, Schrauwen P, Schrauwen-Hinderling VB, Kooi ME. Geometrical models for cardiac MRI in rodents: comparison of quantification of left ventricular volumes and function by various geometrical models with a full-volume MRI data set in rodents. Am J Physiol Heart Circ Physiol 302: H709-H715, 2012. First published November 18, 2011; doi:10.1152/ajpheart.00710.2011.-MRI has been proven to be an accurate method for noninvasive assessment of cardiac function. One of the current limitations of cardiac MRI is that it is time consuming. Therefore, various geometrical models are used, which can reduce scan and postprocessing time. It is unclear how appropriate their use is in rodents. Left ventricular (LV) volumes and ejection fraction (EF) were quantified based on 7.0 Tesla cine-MRI in 12 wild-type (WT) mice, 12 adipose triglyceride lipase knockout (ATGL(-/-)) mice (model of impaired cardiac function), and 11 rats in which we induced cardiac ischemia. The LV volumes and function were either assessed with parallel short-axis slices covering the full volume of the left ventricle (FV, gold standard) or with various geometrical models [modified Simpson rule (SR), biplane ellipsoid (BP), hemisphere cylinder (HC), single-plane ellipsoid (SP), and modified Teichholz Formula (TF)]. Reproducibility of the different models was tested and results were correlated with the gold standard (FV). All models and the FV data set provided reproducible results for the LV volumes and EF, with interclass correlation coefficients >= 0.87. All models significantly over-or underestimated EF, except for SR. Good correlation was found for all volumes and EF for the SR model compared with the FV data set (R-2 ranged between 0.59-0.95 for all parameters). The HC model and BP model also predicted EF well (R-2 >= 0.85), although proved to be less useful for quantitative analysis. The SP and TF models correlated poorly with the FV data set (R-2 >= 0.45 for EF and R-2 >= 0.29 for EF, respectively). For the reduction in acquisition and postprocessing time, only the SR model proved to be a valuable method for calculating LV volumes, stroke volume, and EF

The increase in intramyocellular lipid content is a very early response to training

The present study investigated the influences of a 2-wk training program on intramyocellular lipid (IMCL) content, IMCL decrease during exercise, fat oxidation, and insulin sensitivity. Nine untrained men (age, 23.3 ± 3.2 yr; body mass index, 22.6 ± 2.6 kg/m2; maximal power output, 3.8 ± 0.6 W/kg body weight) trained for 2 wk. Before and after training, subjects cycled for 3 h while substrate oxidation was measured. IMCL content in the vastus lateralis muscle was determined before and after cycling by proton magnetic resonance spectroscopy. Before and after training, insulin sensitivity was assessed by an insulin tolerance test. The training period resulted in a significant increase in IMCL content by 42 ± 14%. IMCL content decreased significantly during cycling. However, 2 wk of training were not sufficient to achieve increases in fat oxidation and/or use of IMCL during exercise. All markers used to test insulin sensitivity point toward improved insulin sensitivity, albeit not significant. We conclude that the increase in IMCL content is a very early response to training, preceding significant changes in insulin sensitivity. The results suggest that the presence of triglycerides alone does not necessarily have detrimental effects on insulin sensitivity. We confirm earlier reports that IMCL contributes to the energy used during prolonged submaximal exercise

Observational Dutch Young Symptomatic StrokE studY (ODYSSEY): Study rationale and protocol of a multicentre prospective cohort study

Background: The proportion of strokes occurring in younger adults has been rising over the past decade. Due to the far longer life expectancy in the young, stroke in this group has an even larger socio-economic impact. However, information on etiology and prognosis remains scarce.Methods/design: ODYSSEY is a multicentre prospective cohort study on the prognosis and risk factors of patients with a first-ever TIA, ischemic stroke or intracerebral hemorrhage aged 18 to 49 years. Our aim is to include 1500 patients. Primary outcome will be all cause mortality and risk of recurrent vascular events. Secondary outcome will be the risk of post-stroke epilepsy and cognitive impairment. Patients will complete structured questionnaires on outcome measures and risk factors. Both well-documented and less well-documented risk factors and potentially acute trigger factors will be investigated. Patients will be followed every 6 months for at least 3 years. In addition, an extensive neuropsychological assessment will be administered both at baseline and 1 year after the stroke/TIA. Furthermore we will include 250 stroke-free controls, who will complete baseline assessment and one neuropsychological assessment.Discussion: ODYSSEY is designed to prospectively determine prognosis after a young stroke and get more insight into etiology of patients with a TIA, ischemic stroke and intracerebral hemorrhage in patients aged 18 to 49 years old in a large sample size

Cognitive performance: a cross-sectional study on serum vitamin D and its interplay with glucose homeostasis in Dutch older adults

Objectives First, the association between serum 25-hydroxyvitamin D (25[OH]D) and cognitive performance was examined. Second, we assessed whether there was evidence for an interplay between 25(OH)D and glucose homeostasis in the association with cognitive performance. Design, Setting, and Participants Associations were studied using cross-sectional data of 776 (3 domains) up to 2722 (1 domain) Dutch community-dwelling older adults, aged 65 years or older. Measurements Serum 25(OH)D, plasma glucose, and insulin concentrations were obtained. Cognitive performance was assessed with an extensive cognitive test battery. Prevalence ratios (PRs) were calculated to quantify the association between 25(OH)D and cognition; poor performance was defined as the worst 10% of the distribution of the cognitive scores. Results The overall median MMSE score was 29 (IQR 28–30). Higher serum 25(OH)D was associated with better attention and working memory, PR 0.50 (95% CI 0.29–0.84) for the third serum 25(OH)D tertile, indicating a 50% lower probability of being a poor performer than participants in the lowest tertile. Beneficial trends were shown for 25(OH)D with executive function and episodic memory. Serum 25(OH)D was not associated with plasma glucose or insulin. Plasma insulin only modified the association between serum 25(OH)D and executive function (P for interaction: .001), suggesting that the improvement in executive function with high 25(OH)D concentrations is stronger in participants with high plasma insulin concentrations compared with those with low plasma insulin concentrations. Conclusion Higher 25(OH)D concentrations significantly associated with better attention and working memory performance. This study does not demonstrate an interplay between serum 25(OH)D and glucose homeostasis in the association with cognitive performance

Fuel reduction of parallel hybrid electric vehicles

This paper compares the benefits of two parallel drivetrain configurations with an integrated starter generator (ISG): one with the ISG connected directly to the engine, and one with the ISG connected to the drivetrain, after the clutch. Both configurations include start-stop operation, but only the latter one can turn off the engine during propulsion. The effect on fuel economy is analyzed by simulations using optimization over a given driving cycle. Results show that with the latter configuration a much higher fuel reduction can be obtained

Optimal control of hybrid vehicles

Optimal Control of Hybrid Vehicles provides a description of power train control for hybrid vehicles. The background, environmental motivation and control challenges associated with hybrid vehicles are introduced. The text includes mathematical models for all relevant components in the hybrid power train. The power split problem in hybrid power trains is formally described and several numerical solutions detailed, including dynamic programming and a novel solution for state-constrained optimal control problems based on Pontryagin’s maximum principle.   Real-time-implementable strategies that can approximate the optimal solution closely are dealt with in depth. Several approaches are discussed and compared, including a state-of-the-art strategy which is adaptive for vehicle conditions like velocity and mass. Two case studies are included in the book: ·        a control strategy for a micro-hybrid power train; and ·        experimental results obtained with a real-time strategy implemented in a hybrid electric truck ·        . Optimal Control of Hybrid Vehicles will appeal to academic researchers and graduate students interested in hybrid vehicle control or in the applications of energy management using optimal control. Practitioners working in the design of control systems for the automotive industry will also find the ideas propounded in this book of interest. Advances in Industrial Control aims to report and encourage the transfer of technology in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. The series offers an opportunity for researchers to present an extended exposition of new work in all aspects of industrial control

Does reactivity exist in children when measuring activity levels with unsealed pedometers ?

INTRODUCTION AND HYPOTHESIS: Levator defects are risk factors for pelvic organ prolapse (POP) and its recurrence. The most widely used scoring systems for severity of defects shown on magnetic resonance imaging (MRI) and perineal ultrasound (US) are not identical. The aim of this study was to investigate the differences between these classification systems with regard to levator defects on US and their clinical relevance for recurrence after prolapse surgery. METHODS: Women with previous cystocele repair underwent transperineal 3D US. Levator defects were graded according to the scoring system described with regard to MRI (DeLancey et al.) and perineal US (Dietz et al.). The results were compared using the weighted kappa and receiver operating characteristic (ROC) curves (SPSS version 20.0). RESULTS: We assessed 152 women. On US classification, more defects were categorized as highest grade compared with MRI classification [n = 64 (42 %) vs. n = 41 (28 %), p < 0.01]. The grades of levator defects on both scoring systems showed very good agreement, with a weighted kappa of 0.82 [95 % confidence interval (CI) 0.75-0.88). The predictive value of scoring systems for cystocele recurrence after prolapse surgery showed an area under the receiver operating curve (AUC) of 0.63 and 0.64, respectively. CONCLUSIONS: Comparison of the two scoring systems showed good agreement but was lowest for the highest-grade defects. There was no difference in predictive value between scoring systems for cystocele recurrence after prolapse surgery