Supernormal functional reserve of apical segments in elite soccer players: an ultrasound speckle tracking handgrip stress study

<p>Abstract</p> <p>Background</p> <p>Ultrasound speckle tracking from grey scale images allows the assessment of regional strain derived from 2D regardless of angle intonation, and it is highly reproducible. The study aimed to evaluate regional left ventricular functional reserve in elite soccer players.</p> <p>Methods</p> <p>50 subjects (25 elite athletes and 25 sedentary controls), aged 26 ± 3.5, were submitted to an echo exam, at rest and after the Hand Grip (HG) test. Both standard echo parameters and strain were evaluated.</p> <p>Results</p> <p>Ejection fraction was similar in athletes and controls both at rest (athletes 58 ± 2 vs controls 57 ± 4 p ns) and after HG (athletes 60 ± 2 vs controls 58 ± 3 p ns). Basal (septal and anterior) segments showed similar strain values in athletes and controls both at rest (athletes S% -19.9 ± 4.2; controls S% -18.8 ± 4.9 p = ns) and after HG (athletes S% -20.99 ± 2.8; controls S% -19.46 ± 4.4 p = ns). Medium-apical segments showed similar strain values at rest (athletes S% -17.31 ± 2.3; controls S% -20.00 ± 5.3 p = ns), but higher values in athletes after HG (athletes S% -24.47 ± 2.8; controls S% -20.47 ± 5.4 p < 0.05)</p> <p>Conclusion</p> <p>In athletes with physiological myocardial hypertrophy, a brief isometric effort produces enhancement of the strain in medium-apical left ventricular segments, suggesting the presence of a higher regional function reserve which can be elicited with an inotropic challenge and suitable methods of radial function quantification such as 2D-derived strain.</p

Do dominant firms provide more training?

A canonical Cournot competition model shows that the profitability of training can increase as the number of competitors decreases. British establishment evidence from 1998, 2004, and 2011 confirms that firms in less competitive markets provide more formal training. This persists within three separate cross-sections and in two separate panel estimates. It persists with alternative measures of training, with alternative measures of market competition and in estimates designed to account for endogeneity. These results suggest that a dominant product market position, indeed, increases the incentives to invest in training

Poaching and Firm-Sponsored Training

A series of seminal theoretical papers argues that poaching of employees may hamper company-sponsored general training like apprenticeship training in Germany. Empirically however, the existence, extent and consequences of poaching still remain an open question. We provide a novel empirical strategy to identify poaching and investigate its causes and consequences. We find that only a few apprenticeship training firms in Germany are poaching victims or raiders. Poaching victim firms are more likely to be in a temporary downturn and raiding firms are more likely to increase their workforce. Poaching victims hardly change their training strategy after poaching. Thus, poaching is a transitory event and not a general threat to apprenticeship training. This is an important result for countries that intend to introduce apprenticeship type of training and need to convince firms to participate in their endeavour

Tissue Doppler Imaging can be useful to distinguish pathological from physiological left ventricular hypertrophy: a study in master athletes and mild hypertensive subjects

<p>Abstract</p> <p>Background</p> <p>Transthoracic echocardiography left ventricular wall thickness is often increased in master athletes and it results by intense physical training. Left Ventricular Hypertrophy can also be due to a constant pressure overload. Conventional Pulsed Wave (PW) Doppler analysis of diastolic function sometimes fails to distinguish physiological from pathological LVH.</p> <p>The aim of this study is to evaluate the role of Pulsed Wave Tissue Doppler Imaging in differentiating pathological from physiological LVH in the middle-aged population.</p> <p>Methods</p> <p>we selected a group of 80 master athletes, a group of 80 sedentary subjects with essential hypertension and an apparent normal diastolic function at standard PW Doppler analysis. The two groups were comparable for increased left ventricular wall thickness and mass index (134.4 ± 19.7 vs 134.5 ± 22.1 gr/m2; p > .05). Diastolic function indexes using the PW technique were in the normal range for both.</p> <p>Results</p> <p>Pulsed Wave TDI study of diastolic function immediately distinguished the two groups. While in master athletes the diastolic TDI-derived parameters remained within normal range (E' 9.4 ± 3.1 cm/sec; E/E' 7.8 ± 2.1), in the hypertensive group these parameters were found to be constantly altered, with mean values and variation ranges always outside normal validated limits (E' 7.2 ± 2.4 cm/sec; E/E' 10.6 ± 3.2), and with E' and E/E' statistically different in the two groups (p < .001).</p> <p>Conclusion</p> <p>Our study showed that the TDI technique can be an easy and validated method to assess diastolic function in differentiating normal from pseudonormal diastolic patterns and it can distinguish physiological from pathological LVH emphasizing the eligibility certification required by legal medical legislation as in Italy.</p

The effect of variable troponin C mutation thin filament incorporation on cardiac muscle twitch contractions

One of the complexities of understanding the pathology of familial forms of cardiac diseases is the level of mutation incorporation in sarcomeres. Computational models of the sarcomere that are spatially explicit offer an approach to study aspects of mutational incorporation into myofilaments that are more challenging to get at experimentally. We studied two well characterized mutations of cardiac TnC, L48Q and I61Q, that decrease or increase the release rate of Ca2+ from cTnC, k-Ca, resulting in HCM and DCM respectively [1]. Expression of these mutations in transgenic mice was used to provide experimental data for incorporation of 30 and 50% (respectively) into sarcomeres. Here we demonstrate that fixed length twitch contractions of trabeculae from mice containing mutant differ from WT; L48Q trabeculae have slower relaxation while I61Q trabeculae have markedly reduced peak tension. Using our multiscale modelling approach [2] we were able to describe the tension transients of WT mouse myocardium. Tension transients for the mutant cTnCs were simulated with changes in k-Ca, measured experimentally for each cTnC mutant in whole troponin complex, a change in the affinity of cTnC for cTnI, and a reduction in the number of detached crossbridges available for binding. A major advantage of the multiscale explicit 3-D model is that it predicts the effects of variable mutation incorporation, and the effects of variations in mutation distribution within thin filaments in sarcomeres. Such effects are currently impossible to explore experimentally. We explored random and clustered distributions of mutant cTnCs in thin filaments, as well as distributions of individual thin filaments with only WT or mutant cTnCs present. The effects of variable amounts of incorporation and non-random distribution of mutant cTnCs are more marked for I61Q than L48Q cTnC. We conclude that this approach can be effective for study on mutations in multiple proteins of the sarcomere. SUMMARY: A challenge in experimental studies of diseases is accounting for the effect of variable mutation incorporation into myofilaments. Here we use a spatially explicit computational approach, informed by experimental data from transgenic mice expressing one of two mutations in cardiac Troponin C that increase or decrease calcium sensitivity. We demonstrate that the model can accurately describe twitch contractions for the data and go on to explore the effect of variable mutant incorporation and localization on simulated cardiac muscle twitches

Worker-financed versus Firm-sponsored Training: How are Skilled Workers Supplied to the Economy?

A search and matching model of general human capital is developed to contrast worker-financed training with firm-sponsored training, to evaluate which type of training might prevail in the economy. It will be shown that firm-sponsored training is more likely to occur when there is greater friction in the labour market, whereas worker-financed training prevails in a less frictional market. Moreover, the model has multiple equilibria in labour markets with intermediate friction. Comparative statistics exercises tell us that reductions in labour market friction result in less firm-sponsored training in the economy, but encourage worker-financed training. Copyright (c) The London School of Economics and Political Science 2008.

Strain values show a slight but not significant increase from basal to apical segments in both situations

<p><b>Copyright information:</b></p><p>Taken from "Supernormal functional reserve of apical segments in elite soccer players: an ultrasound speckle tracking handgrip stress study"</p><p>http://www.cardiovascularultrasound.com/content/6/1/14</p><p>Cardiovascular Ultrasound 2008;6():14-14.</p><p>Published online 16 Apr 2008</p><p>PMCID:PMC2329600.</p><p></p

The endocardial border of the 2D left ventricular chamber is automatically followed in time frame by frame

There is no obvious differences in strain in basal and apical segments at rest, but a significant increase after HG.<p><b>Copyright information:</b></p><p>Taken from "Supernormal functional reserve of apical segments in elite soccer players: an ultrasound speckle tracking handgrip stress study"</p><p>http://www.cardiovascularultrasound.com/content/6/1/14</p><p>Cardiovascular Ultrasound 2008;6():14-14.</p><p>Published online 16 Apr 2008</p><p>PMCID:PMC2329600.</p><p></p