Influence of different dynamic sporting disciplines on right ventricular Structure and function in elite male athletes.

Our objective was to assess the influence of different levels of exposure to dynamic training on right ventricular (RV) structure, function and mechanics in elite male athletes. We recruited 492 male elite athletes aged between 18 and 30 years old. Athletes were grouped according to their sporting discipline using the Mitchell Classification as Low Dynamic (LD), Moderate Dynamic (MD) or High Dynamic (HD). All participants underwent 2D, Doppler, tissue Doppler and strain (ε) echocardiography with a focused and comprehensive assessment of the right heart. Athletes involved in MD sports had the largest absolute RV chamber size and when scaled to body size RVOT PLAX, RVOT2, RVD1 and RVD3 were larger in HD compared to MD and LD athletes. There were no between group differences in conventional RV functional indices as well as global RV ε (LD: - 23.4 ± 3.1 vs. MD: - 22.7 ± 2.7 vs. HD: - 23.5 ± 2.6, %) and strain rate (P > 0.01). The base to apex ε gradient in the RV septum was lower in the MD athletes compared to HD and LD due to a lower apical septal ε which significantly correlated with absolute RV chamber size. After scaling for body size there was evidence of larger RV cavities in both MD and HD athletes compared to LD athletes. Global RV function, ε and strain rate were not different between groups. MD athletes had lower apical septal ε that contributed to a smaller base-to-apex ε gradient that is partially associated with larger absolute RV chamber dimensions

Solving the radial Dirac equations: a numerical odyssey

We discuss, in a pedagogical way, how to solve for relativistic wave functions from the radial Dirac equations. After an brief introduction, in Section II we solve the equations for a linear Lorentz scalar potential, V_s(r), that provides for confinement of a quark. The case of massless u and d quarks is treated first, as these are necessarily quite relativistic. We use an iterative procedure to find the eigenenergies and the upper and lower component wave functions for the ground state and then, later, some excited states. Solutions for the massive quarks (s, c, and b) are also presented. In Section III we solve for the case of a Coulomb potential, which is a time-like component of a Lorentz vector potential, V_v(r). We re-derive, numerically, the (analytically well-known) relativistic hydrogen atom eigenenergies and wave functions, and later extend that to the cases of heavier one-electron atoms and muonic atoms. Finally, Section IV finds solutions for a combination of the V_s and V_v potentials. We treat two cases. The first is one in which V_s is the linear potential used in Sec. II and V_v is Coulombic, as in Sec. III. The other is when both V_s and V_v are linearly confining, and we establish when these potentials give a vanishing spin-orbit interaction (as has been shown to be the case in quark models of the hadronic spectrum).Comment: 39 pages (total), 23 figures, 2 table

Left ventricular remodeling in elite and sub-elite road cyclists.

Marked adaptation of left ventricular (LV) structure in endurance athletes is well established. However, previous investigations of functional and mechanical adaptation have been contradictory. A lack of clarity in subjects' athletic performance level may have contributed to these disparate findings. This study aimed to describe structural, functional, and mechanical characteristics of the cyclists' LV, based on clearly defined performance levels. Male elite cyclists (EC) (n = 69), sub-elite cyclists (SEC) (n = 30), and non-athletes (NA) (n = 46) were comparatively studied using conventional and speckle tracking 2D echocardiography. Dilated eccentric hypertrophy was common in EC (34.7%), but not SEC (3.3%). Chamber concentricity was higher in EC compared to SEC (7.11 ± 1.08 vs 5.85 ± 0.98 g/(mL)2/3 , P < .001). Ejection fraction (EF) was lower in EC compared to NA (57 ± 5% vs 59 ± 4%, P < .05), and reduced EF was observed in a greater proportion of EC (11.6%) compared to SEC (6.7%). Global circumferential strain (GCε) was greater in EC (-18.4 ± 2.4%) and SEC (-19.8 ± 2.7%) compared to NA (-17.2 ± 2.6%) (P < .05 and P < .001). Early diastolic filling was lower in EC compared with SEC (0.72 ± 0.14 vs 0.88 ± 0.12 cm/s, P < .001), as were septal E' (12 ± 2 vs 15 ± 2 cm/s, P < .001) and lateral E' (18 ± 4 vs 20 ± 4 cm/s, P < .05). The magnitude of LV structural adaptation was far greater in EC compared with SEC. Increased GCε may represent a compensatory mechanism to maintain stroke volume in the presence of increased chamber volume. Decreased E and E' velocities may be indicative of a considerable functional reserve in EC

Contribution of extracellular negatively charged residues to ATP action and zinc modulation of rat P2X 2 receptors

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65506/1/j.1471-4159.2008.05228.x.pd

Glucose and lactate as metabolic constraints on presynaptic transmission at an excitatory synapse

The synapse has high energy demands, which increase during intense activity. Presynaptic ATP production depends on substrate availability and usage will increase during activity, which in turn could influence transmitter release and information transmission. We investigated transmitter release at the mouse calyx of Held synapse using glucose or lactate (10, 1 or 0 mm) as the extracellular substrates while inducing metabolic stress. High‐frequency stimulation (HFS) and recovery paradigms evoked trains of EPSCs monitored under voltage‐clamp. Whilst postsynaptic intracellular ATP was stabilised by diffusion from the patch pipette, depletion of glucose increased EPSC depression during HFS and impaired subsequent recovery. Computational modelling of these data demonstrated a reduction in the number of functional release sites and slowed vesicle pool replenishment during metabolic stress, with little change in release probability. Directly depleting presynaptic terminal ATP impaired transmitter release in an analogous manner to glucose depletion. In the absence of glucose, presynaptic terminal metabolism could utilise lactate from the aCSF and this was blocked by inhibition of monocarboxylate transporters (MCTs). MCT inhibitors significantly suppressed transmission in low glucose, implying that lactate is a presynaptic substrate. Additionally, block of glycogenolysis accelerated synaptic transmission failure in the absence of extracellular glucose, consistent with supplemental supply of lactate by local astrocytes. We conclude that both glucose and lactate support presynaptic metabolism and that limited availability, exacerbated by high‐intensity firing, constrains presynaptic ATP, impeding transmission through a reduction in functional presynaptic release sites as vesicle recycling slows when ATP levels are low

Risk Factors for Severe Renal Disease in Bardet-Biedl Syndrome

Bardet-Biedl syndrome is a rare autosomal recessive, multisystem disease characterized by retinal dystrophy, renal malformation, obesity, intellectual disability, polydactyly, and hypogonadism. Nineteen disease-causing genes (BBS1-19) have been identified, of which mutations in BBS1 are most common in North America and Europe. A hallmark of the disease, renal malformation is heterogeneous and is a cause of morbidity and mortality through the development of CKD. We studied the prevalence and severity of CKD in 350 patients with Bardet-Biedl syndrome-related renal disease attending the United Kingdom national Bardet-Biedl syndrome clinics to further elucidate the phenotype and identify risk indicators of CKD. Overall, 31% of children and 42% of adults had CKD; 6% of children and 8% of adults had stage 4-5 CKD. In children, renal disease was often detected within the first year of life. Analysis of the most commonly mutated disease-associated genes revealed that, compared with two truncating mutations, two missense mutations associated with less severe CKD in adults. Moreover, compared with mutations in BBS10, mutations in BBS1 associated with less severe CKD or lack of CKD in adults. Finally, 51% of patients with available ultrasounds had structural renal abnormalities, and 35% of adults were hypertensive. The presence of structural abnormalities or antihypertensive medication also correlated statistically with stage 3b-5 CKD. This study describes the largest reported cohort of patients with renal disease in Bardet-Biedl syndrome and identifies risk factors to be considered in genetic counseling

'Reclaiming the criminal' : the role and training of prison officers in England, 1877-1914

This article examines the role and training of prison officers in England, between 1877 and 1914. It is concerned with the changing penal philosophies and practices of this period and how these were implemented in local prisons, and the duties of the prison officer. More broadly, this article argues that the role of the prison officer and their training (from 1896) reflect wider ambiguities in prison policy and practice during this period

A unified approach for the solution of the Fokker-Planck equation

This paper explores the use of a discrete singular convolution algorithm as a unified approach for numerical integration of the Fokker-Planck equation. The unified features of the discrete singular convolution algorithm are discussed. It is demonstrated that different implementations of the present algorithm, such as global, local, Galerkin, collocation, and finite difference, can be deduced from a single starting point. Three benchmark stochastic systems, the repulsive Wong process, the Black-Scholes equation and a genuine nonlinear model, are employed to illustrate the robustness and to test accuracy of the present approach for the solution of the Fokker-Planck equation via a time-dependent method. An additional example, the incompressible Euler equation, is used to further validate the present approach for more difficult problems. Numerical results indicate that the present unified approach is robust and accurate for solving the Fokker-Planck equation.Comment: 19 page