Exercise and Coronary Atherosclerosis: Observations, Explanations, Relevance, and Clinical Management.

Physical activity and exercise training are effective strategies for reducing the risk of cardiovascular events, but multiple studies have reported an increased prevalence of coronary atherosclerosis, usually measured as coronary artery calcification, among athletes who are middle-aged and older. Our review of the medical literature demonstrates that the prevalence of coronary artery calcification and atherosclerotic plaques, which are strong predictors for future cardiovascular morbidity and mortality, was higher in athletes compared with controls, and was higher in the most active athletes compared with less active athletes. However, analysis of plaque morphology revealed fewer mixed plaques and more often only calcified plaques among athletes, suggesting a more benign composition of atherosclerotic plaques. This review describes the effects of physical activity and exercise training on coronary atherosclerosis in athletes who are middle-aged and older and aims to contribute to the understanding of the potential adverse effects of the highest doses of exercise training on the coronary arteries. For this purpose, we will review the association between exercise and coronary atherosclerosis measured using computed tomography, discuss the potential underlying mechanisms for exercise-induced coronary atherosclerosis, determine the clinical relevance of coronary atherosclerosis in middle-aged athletes and describe strategies for the clinical management of athletes with coronary atherosclerosis to guide physicians in clinical decision making and treatment of athletes with elevated coronary artery calcification scores

Получение желаемых передаточных функций импульсных систем автоматического управления

Рассмотрена задача получения желаемых передаточных функций импульсных систем автоматического управления. Предложен способ синтеза передаточных функций низкого порядка по прямым показателям качества, обеспечивающий конечное время переходного процесса

Untersuchungen zum Amphibienbestand eines Feuchtgebietes in Osnabrück : mit 2 Tabellen

Im Rahmen der Projekt-Lehrveranstaltung "Angewandte Biotopforschung" an der Universität Osnabrück wurden im Jahre 1987 in einem kleinen Feuchtgebiet des Osnabrükker Stadtteils Atter Untersuchungen an den dortigen Amphibienbeständen durchgeführt. Dabei konnten 9 Arten nachgewiesen werden: Erdkröte (Bufo bufo), Grasfrosch (Rana temporaria), Moorfrosch (Rana arvalis), Wasserfrosch (Rana esculenta), Laubfrosch (Hyla arborea), Teichmolch (Triturus vulgaris), Fadenmolch (T. helveticus), Bergmolch (T. alpestris) und Kammolch (T. cristatus). 4 der Arten stehen auf der Roten Liste. Bedingt durch das kalte Frühjahr 1987 erfolgten die Wanderungen zu den Laichgewässern sehr spät. Negative Entwicklungen und Einflüsse, die im Gebiet beobachtbar sind, sollten durch die Ausweisung als "Flächenhaftes Naturdenkmal" eingedämmt werden. Über einen Pflege- und Entwicklungsplan wäre das Gelände zu verbessern

Plastic microbeads from cosmetic products: an experimental study of their hydrodynamic behaviour, vertical transport and resuspension in phytoplankton and sediment aggregates

Hydrodynamic behaviour and the transport pathways of microplastics within the ocean environment are not well known, rendering accurate predictive models for dispersal management of such pollutants difficult to establish. In the natural environment, aggregation between plastic microbeads and phytodetritus or suspended sediments in rivers and oceans further complicate the patterns of dispersal. In this laboratory study, the physical characteristics and hydrodynamic behaviour of a selection of common plastic microbeads, as used in exfoliation skincare cosmetic products, were investigated. Additionally, the potential for aggregation of these microbeads with phytodetritus and suspended sediments, as well as the subsequent sinking and resuspension behaviour of produced aggregates, were investigated with roller tanks, settling columns and erosion chamber. Physical characteristics of the plastic microbeads showed great heterogeneity, with various densities, sizes and shapes of plastic material being utilised in products designed for the same purpose. The majority of the plastics investigated were positively buoyant in both freshwater and seawater. Aggregation between plastic microbeads and phytoplankton was observed to be swift, with even extremely high concentrations of plastics being rapidly scavenged by suspended algal material. Following aggregation to sizes of 300 to 4400 μm diameter, some formerly buoyant plastics were observed to settle through the water column and enter the benthic boundary layer with settling velocities ranging between 32 and 831 m day–1. These aggregates could be resuspended in the laboratory under critical shear velocities of 0.67–1.33 cm s–1 (free stream velocities of > 10 cm s–1). This rapid aggregation and subsequent settling indicates a potentially important transport pathway for these waste products, a pathway that should be considered when modelling discharge and transport of plastic microbeads and determining the ecosystems that may be at risk from exposure

Der steinige Weg in den Unterricht. Entwicklung und Implementation einer digitalen Lernleiter im Fach Chemie

Nur wenige pädagogische und fachdidaktische Innovationen lassen sich ohne Hindernisse in den Unterricht übertragen. Dies liegt vor allem daran, dass das System Schule von vielen ineinandergreifenden und voneinander abhängigen Faktoren und Variablen bestimmt wird, die im Zuge der Entwicklung und Evaluation von Innovationen kaum umfassend berücksichtigt und unmöglich in ihrem (wechselseitigen) Einfluss untersucht werden können. Daher wird zunehmend nach Transferlösungen gesucht, die eine Implementation von empirisch erprobten oder auch theoretisch abgeleiteten Innovationen in der Praxis begünstigen. Ein vielversprechender Ansatz sind Wissenschaft-Praxis-Kooperationen. Wesentliches Kennzeichen ist die gemeinsame Entwicklung, Evaluation und Implementation von Innovationen durch Akteur:innen der Bildungsforschung und der Unterrichtspraxis mit dem Ziel, die Innovationen nachhaltig und für die Schüler:innen lernwirksam anzulegen. Ein solcher Ansatz ist der symbiotische Implementationsansatz, der im Rahmen des im Ruhrgebiet laufenden und durch die RAG-Stiftung ermöglichten Projekts «Lernerfolg mit der digitalen Lernleiter» Anwendung findet. Im Beitrag werden die Herausforderungen des Ansatzes im Kontext der Digitalisierung von Schule und Unterricht dargestellt und Erkenntnisse für zukünftige Projekte abgeleitet

The impact of remote ischemic preconditioning on cardiac biomarker and functional response to endurance exercise.

Remote ischemic preconditioning (RIPC; repeated short reversible periods of ischemia) protects the heart against subsequent ischemic injury. We explored whether RIPC can attenuate post-exercise changes in cardiac troponin T (cTnT) and cardiac function in healthy individuals. In a randomized, crossover design, 14 participants completed 1-h cycling time trials (TT) on two separate visits; preceded by RIPC (arms/legs, 4 × 5-min 220 mmHg), or SHAM-RIPC (20 mmHg). Venous blood was sampled before and 0-, 1-, and 3-h post-exercise to assess high sensitivity (hs-)cTnT and brain natriuretic peptide (NT-proBNP). Echocardiograms were performed at the same time points to assess left and right ventricular systolic (ejection fraction; EF and right ventricular fractional area change; RVFAC, respectively) and diastolic (early transmitral flow velocities; E) function. Baseline hs-cTnT was not different between RIPC and SHAM. Post-exercise hs-cTnT levels were consistently lower following RIPC (18 ± 3 vs 21 ± 3; 19 ± 3 vs 23 ± 3; and 20 ± 2 vs 25 ± 2 ng/L at 0, 1 and 3-h post-exercise, respectively; P < 0.05). There was no main effect of time, trial, or interaction for NT-proBNP and left ventricular EF or RVFAC (all P < 0.05). A main effect of time was evident for E which transiently declined immediately after exercise to a similar level in both trials (0.85 ± 0.04 vs 0.74 ± 0.04 m/s, respectively; P < 0.05). In summary, RIPC was associated with lower hs-cTnT levels after exercise but there was no independent effect of RIPC for NT-proBNP or LV systolic and diastolic function. The lower hs-cTnT levels after RIPC suggests that further research should evaluate the role of ischemia in exercise-induced elevation in hs-cTnT

Cardiac computed tomography and myocardial perfusion scintigraphy for risk stratification in asymptomatic individuals without known cardiovascular disease: a position statement of the Working Group on Nuclear Cardiology and Cardiac CT of the European Society of Cardiology

Cardiovascular events remain one of the most frequent causes of mortality and morbidity worldwide. The majority of cardiac events occur in individuals without known coronary artery disease (CAD) and in low- to intermediate-risk subjects. Thus, the development of improved preventive strategies may substantially benefit from the identification, among apparently intermediate-risk subjects, of those who have a high probability for developing future cardiac events. Cardiac computed tomography and myocardial perfusion scintigraphy (MPS) by single photon emission computed tomography may play a role in this setting. In fact, absence of coronary calcium in cardiac computed tomography and inducible ischaemia in MPS are associated with a very low rate of major cardiac events in the next 3-5 years. Based on current evidence, the evaluation of coronary calcium in primary prevention subjects should be considered in patients classified as intermediate-risk based on traditional risk factors, since high calcium scores identify subjects at high-risk who may benefit from aggressive secondary prevention strategies. In addition, calcium scoring should be considered for asymptomatic type 2 diabetic patients without known CAD to select those in whom further functional testing by MPS or other stress imaging techniques may be considered to identify patients with significant inducible ischaemia. From available data, the use of MPS as first line testing modality for risk stratification is not recommended in any category of primary prevention subjects with the possible exception of first-degree relatives of patients with premature CAD in whom MPS may be considered. However, the Working Group recognizes that neither the use of computed tomography for calcium imaging nor of MPS have been proven to significantly improve clinical outcomes of primary prevention subjects in prospective controlled studies. This information would be crucial to adequately define the role of imaging approaches in cardiovascular preventive strategie

Secondhand Smoke Exposure and Coronary Artery Calcification among Nonsmoking Participants of a Population-Based Cohort

Background: Secondhand smoke (SHS) consists of fine particulate matter, carcinogens, and various toxins that affect large parts of the population. SHS increases the risk for acute cardiovascular events and may contribute to the development of atherosclerosis