Development of gonadotropin-releasing hormone systems in the male African catfish, Clarias gariepinus

Reproductive processes are mainly regulated by the brain-pituitary-gonad axis (BPG-axis). Gonadotropin-releasing hormone (GnRH) neurons localized in the brain release their hormone GnRH, which allows the release of gonadotropic hormone by gonadotropic cells in the pituitary. Gonadotropic hormone, in turn, regulates the production of sex steroids and germ cells in the gonads. The steroids complete the dynamic BPG-axis by exerting feedback effects at the level of the brain, pituitary and gonads. The transition period of a juvenile, inactive axis towards a mature, functional system is known as puberty. The prevailing "missing-link" concept assumes that one or more components of the axis are absent or not functional before puberty. For our animal model, the African catfish, it has been proposed that sex steroids initiate and/or accelerate pubertal development. However, based on earlier findings, it was suggested that the "missing link" could also be localized at a higher level of the BPG-axis, i.e. at the GnRH system in the brain. In order to test the hypothesis that sex steroids and/or a functional GnRH system are important determinants in the onset of puberty in the African catfish, we studied the normal development of the GnRH system in the brain and the effects of certain steroids on this development. The present thesis shows that specific sex steroids are important for the development of GnRH neurons. Thus, in the African catfish, steroids are a serious candidate for the "missing-link", since it is required for activating the GnRH neurons in the preparation for the onset of puberty. Another candidate for the "missing-link" is the actual released amount of GnRH that is available for the gonadotropic cells at the onset of puberty. We hypothesize that functional contact between the first GnRH terminals in the pituitary and the gonadotropic cells is required for the initiation of puberty. Once this switch is turned on, the three levels of the BPG-axis simultaneously display their maturational processes: innervation of the pituitary by GnRH fibers, development of gonadotropic cells and the first wave of spermatogenesis

Diagnostic approach for myocardial contusion: a retrospective evaluation of patient data and review of the literature

Purpose: Myocardial contusion can be a life-threatening condition in patients who sustained blunt thoracic trauma. The diagnostic approach remains a subject of debate. The aim of this study was to determine the sensiti

Medical students' perspectives on online proctoring during remote digital progress test

Remote teaching and assessment are essential for current education. During online examination, online proctoring is often used as a surveillance tool. Little is known about student perceptions on online proctoring. Using an online questionnaire, we found that medical students worry most about unjustified invalidation of their exam due to unstable internet connection, background noise or webcam issues, and privacy issues. It is important to be aware of these worries as they may influence test results.Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Mechanical Support in Early Cardiogenic Shock: What Is the Role of Intra-aortic Balloon Counterpulsation?

Purpose of Review: We aim to summarize recent insights and provide an up-to-date overview on the role of intra-aortic balloon pump (IABP) counterpulsation in cardiogenic shock (CS). Recent Findings: In the largest randomized controlled trial (RCT) of patients with CS after acute myocardial infarction

Difference of \tilde \epsilon and \epsilon in fitting the parameters of CKM matrix

The difference between induced by box diagram value of \tilde \epsilon and experimentally measured value of \epsilon is estimated. It appeared to be around 5 - 10 %, depending on the values of hadronic matrix elements. With this result, the fit of CKM marix parameters within the SM is performed.Comment: 11 pages, 1 figur

HEART score improves efficiency of coronary computed tomography angiography in patients suspected of acute coronary syndrome in the emergency department

Aims: Coronary computed tomography angiography is increasingly employed in the emergency department for suspected acute coronary syndrome patients. The HEART score has been proposed for initial risk stratification in these patients. The aim of this study was to investigate the diagnostic value and efficiency of the HEART score before coronary computed tomography angiography. Methods and results: We included patients suspected of acute coronary syndrome who underwent coronary computed tomography angiography in the emergency department. Based on the HEART score, patients were stratified as low-risk (HEART≤3), intermediate-risk (HEART4–6) and high-risk (HEART≥7). We assessed coronary computed tomography angiography for the presence of significant coronary artery disease (>50% stenosis). The primary outcome, the level of major adverse cardiac events, was a composite endpoint of all-cause mortality, acute coronary syndrome or coronary revascularisation within 30 days. The study population consisted of 340 patients (mean age: 55.6±10.1 years, 44.7% women), major adverse cardiac events occurred in 45 (13.2%) patients. The incidence of major adverse cardiac events in patients stratified as low-risk (35.0%), intermediate-risk (56.8%) and high-risk

Magnetic fields in cosmic particle acceleration sources

We review here some magnetic phenomena in astrophysical particle accelerators associated with collisionless shocks in supernova remnants, radio galaxies and clusters of galaxies. A specific feature is that the accelerated particles can play an important role in magnetic field evolution in the objects. We discuss a number of CR-driven, magnetic field amplification processes that are likely to operate when diffusive shock acceleration (DSA) becomes efficient and nonlinear. The turbulent magnetic fields produced by these processes determine the maximum energies of accelerated particles and result in specific features in the observed photon radiation of the sources. Equally important, magnetic field amplification by the CR currents and pressure anisotropies may affect the shocked gas temperatures and compression, both in the shock precursor and in the downstream flow, if the shock is an efficient CR accelerator. Strong fluctuations of the magnetic field on scales above the radiation formation length in the shock vicinity result in intermittent structures observable in synchrotron emission images. Resonant and non-resonant CR streaming instabilities in the shock precursor can generate mesoscale magnetic fields with scale-sizes comparable to supernova remnants and even superbubbles. This opens the possibility that magnetic fields in the earliest galaxies were produced by the first generation Population III supernova remnants and by clustered supernovae in star forming regions.Comment: 30 pages, Space Science Review

Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider

This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-→e+e- and (for the ϒ(4S) only) e+e-→μ+μ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-→e+e- and e+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the ϒ(3S) and ϒ(2S) resonances, an additional uncertainty arises due to ϒ→e+e-X background. For data collected off the ϒ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the ϒ(4S), 0.58% (0.72%) for the ϒ(3S), and 0.68% (0.88%) for the ϒ(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l’Energie Atomique and Institut National de Physique Nucléaire et de Physiquedes Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovación (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter