Accelerating global left-ventricular function assessment in mice using reduced slice acquisition and three-dimensional guide-point modelling

<p>Abstract</p> <p>Background</p> <p>To investigate the utility of three-dimensional guide-point modeling (GPM) to reduce the time required for CMR evaluation of global cardiac function in mice, by reducing the number of image slices required for accurate quantification of left-ventricular (LV) mass and volumes.</p> <p>Methods</p> <p>Five female C57Bl/6 mice 8 weeks post myocardial infarction induced by permanent occlusion of the left coronary artery, and six male control (un-operated) C57Bl/6 mice, were subject to CMR examination under isoflurane anaesthesia. Contiguous short axis (SAX) slices (1 mm thick 7-9 slices) were obtained together with two long axis (LAX) slices in two chamber and four chamber orientations. Using a mathematical model of the heart to interpolate information between the available slices, GPM LV mass and volumes were determined using full slice (all SAX and two LAX), six slice (four SAX and two LAX) and four slice (two SAX and two LAX) analysis protocols. All results were compared with standard manual volumetric analysis using all SAX slices.</p> <p>Results</p> <p>Infarct size was 39.1 ± 5.1% of LV myocardium. No significant differences were found in left ventricular mass and volumes between the standard and GPM full and six slice protocols in infarcted mice (113 ± 10, 116 ± 11, and 117 ± 11 mg respectively for mass), or between the standard and GPM full, six and four slice protocols in control mice, (105 ± 14, 106 ± 10, 104 ± 12, and 105 ± 7 mg respectively for mass). Significant differences were found in LV mass (135 ± 18 mg) and EF using the GPM four slice protocol in infarcted mice (p < 0.05).</p> <p>Conclusion</p> <p>GPM enables accurate analysis of LV function in mice with relatively large infarcts using a reduced six slice acquisition protocol, and in mice with normal/symmetrical left-ventricular topology using a four slice protocol.</p

Brain macrophages and microglia in human fetal hydrocephalus

Whereas several studies have addressed the activation of microglia (the resident mononuclear phagocytes of the brain) and macrophages within the nervous system in experimental animal models of congenital and induced hydrocephalus, little is known of their state of activation or regional distribution in human fetal hydrocephalus. This investigation aimed to address such questions. Ten human fetal cases [20-36 gestational weeks (GW) at postmortem] previously diagnosed with hydrocephalus on ultrasound examination in utero, and 10 non-hydrocephalic controls (22-38 GW at postmortem) were assessed immufcnohistochemically with antibodies directed against MHC class II and CD68 antigens, and lectin histochemistry with Lycopersicon esculentum (tomato lectin). Adjacent sections were also immunoreacted with an antiserum to laminin to detect cerebral blood vessels. Eight out of the 10 hydrocephalus cases showed numerous CD68 and tomato lectin-positive macrophages located at focal regions along the ependymal lining of the lateral ventricles (particularly within the occipital horn). However, only five of these cases demonstrated MHC class II positive macrophages associated with the ventricular lining. Microglial reactivity within periventricular regions could also be identified using the lectin in four cases, two of which were also immunoreactive with CD68 (but not with MHC class II). By comparison, in control cases five out of 10 fetal brains (aged between 20 and 24 GW) showed few or no ependymal or supraependymal macrophages. One case at 28 GW, and cases at 32 and 38 GW (two of which were diagnosed with intrauterine hypoxic-ischemia) did, however, show some MHC class II (CD68 negative) cells located at the ependymal surface. Nevertheless, these were not as numerous or intensely immunoreactive as in the hydrocephalus cases. Microglia interspersed throughout the intermediate zone and circumscribing the basal ganglia were within normal confines in all cases examined. Hydrocephalic cases additionally showed focal regions of hypovascularization or alterations in the structure and orientation of capillaries within periventricular areas, compared to controls. The macrophage response detected at the ependymal lining of the ventricles and within the periventricular area in hydrocephalus may be related both to the severity of hydrocephalus and the age of the fetus

Brain macrophages and microglia in human fetal hydrocephalus [poster presentation]

Whereas several studies have addressed the activation of microglia (the resident mononuclear phagocytes of the brain) and macrophages within the nervous system in experimental animal models of congenital and induced hydrocephalus, little is known of their state of activation or regional distribution in human fetal hydrocephalus. This investigation aimed to address such questions. Ten human fetal cases [20-36 gestational weeks (GW) at postmortem] previously diagnosed with hydrocephalus on ultrasound examination in utero, and 10 non-hydrocephalic controls (22-38 GW at postmortem) were assessed immufcnohistochemically with antibodies directed against MHC class II and CD68 antigens, and lectin histochemistry with Lycopersicon esculentum (tomato lectin). Adjacent sections were also immunoreacted with an antiserum to laminin to detect cerebral blood vessels. Eight out of the 10 hydrocephalus cases showed numerous CD68 and tomato lectin-positive macrophages located at focal regions along the ependymal lining of the lateral ventricles (particularly within the occipital horn). However, only five of these cases demonstrated MHC class II positive macrophages associated with the ventricular lining. Microglial reactivity within periventricular regions could also be identified using the lectin in four cases, two of which were also immunoreactive with CD68 (but not with MHC class II). By comparison, in control cases five out of 10 fetal brains (aged between 20 and 24 GW) showed few or no ependymal or supraependymal macrophages. One case at 28 GW, and cases at 32 and 38 GW (two of which were diagnosed with intrauterine hypoxic-ischemia) did, however, show some MHC class II (CD68 negative) cells located at the ependymal surface. Nevertheless, these were not as numerous or intensely immunoreactive as in the hydrocephalus cases. Microglia interspersed throughout the intermediate zone and circumscribing the basal ganglia were within normal confines in all cases examined. Hydrocephalic cases additionally showed focal regions of hypovascularization or alterations in the structure and orientation of capillaries within periventricular areas, compared to controls. The macrophage response detected at the ependymal lining of the ventricles and within the periventricular area in hydrocephalus may be related both to the severity of hydrocephalus and the age of the fetus

Teacher students’ epistemic beliefs about general pedagogical knowledge: Topic-, source- and context specificity

Pädagogisches Wissen gilt als wichtiger Bestandteil der professionellen Kompetenz von (angehenden) Lehrkräften. Epistemologische Überzeugungen (Überzeugungen bzgl. der Natur und Genese wissenschaftlichen Wissens) werden ebenfalls als Bestandteil professioneller Kompetenz verstanden. Motiviert durch aktuelle Entwicklungsfelder der pädagogisch-psychologischen Forschung zu allgemeinen epistemologischen Überzeugungen, untersucht der vorliegende Beitrag in einem experimentellen Design, inwiefern epistemologische Überzeugungen Lehr amtsstudierender bezüglich pädagogischen Wissens systematisch über Forschungsgegenstände diverser Subdisziplinen (z. B. Bezugsrahmen-Effekt, Inklusion, Lernen mit Lösungsbeispielen) variieren und welche Effekte verschiedene Quellen des Wissens (Laie, Experte, wiss. Literatur) bzw. die Einbettung des Wissens in schulischen Kontext zeigen. Mehrebenen-(Mehrgruppen-)Strukturgleichungsmodelle, in die 1938 Relativismuseinschätzungen von 323 Lehramts studierenden eingingen, zeigen starke Hinweise auf eine deutliche Varianz der epistemologischen Überzeugungen über die verschiedenen Forschungsgegenstände hinweg sowie für eine geringe relativistische Sichtweise des Wissens von „Experten“. Die Einbettung des Wissens in schulischen Kontext zeigte keine signifikanten Effekte. Konsequenzen für die Erfassung spezifischer epistemologischer Überzeugungen sowie Folgerungen für Lehr-Lernprozesse in der Lehrerbildung werden diskutiert. (DIPF/Orig.)Pedagogical content knowledge is known as an important part of the professional competence of teachers. Epistemic beliefs (beliefs about the nature of knowing and knowledge) are part of some influential models of teachers’ professional competence, too. The current experimental study investigates how epistemic beliefs about pedagogical content knowledge of teacher students vary over different topics (Big-Fish-Little-Pond effect, learning with worked out examples, etc.) and which effects the source (layperson, expert advise, scientific study) and context (school context, other contexts) shows. Multigroup multilevel structural equation models of 1938 epistemic beliefs ratings from 323 student teachers show evidence for a high within-person variance in epistemic beliefs as well as less relativistic beliefs for pedagogical knowledge retrieved from “experts”. School context showed no significant effects. Consequences for further examinations of the specificity of epistemic beliefs are discussed as well as consequences of epistemic beliefs for learning processes in teacher education. (DIPF/Orig.