Cerebral Accumulation of Dietary Derivable Plant Sterols does not Interfere with Memory and Anxiety Related Behavior in Abcg5−/− Mice

Plant sterols such as sitosterol and campesterol are frequently applied as functional food in the prevention of atherosclerosis. Recently, it became clear that plasma derived plant sterols accumulate in murine brains. We questioned whether plant sterols in the brain are associated with alterations in brain cholesterol homeostasis and subsequently with brain functions. ATP binding cassette (Abc)g5−/− mice, a phytosterolemia model, were compared to Abcg5+/+ mice for serum and brain plant sterol accumulation and behavioral and cognitive performance. Serum and brain plant sterol concentrations were respectively 35–70-fold and 5–12-fold increased in Abcg5−/− mice (P < 0.001). Plant sterol accumulation resulted in decreased levels of desmosterol (P < 0.01) and 24(S)-hydroxycholesterol (P < 0.01) in the hippocampus, the brain region important for learning and memory functions, and increased lanosterol levels (P < 0.01) in the cortex. However, Abcg5−/− and Abcg5+/+ displayed no differences in memory functions or in anxiety and mood related behavior. The swimming speed of the Abcg5−/− mice was slightly higher compared to Abcg5+/+ mice (P < 0.001). In conclusion, plant sterols in the brains of Abcg5−/− mice did have consequences for brain cholesterol metabolism, but did not lead to an overt phenotype of memory or anxiety related behavior. Thus, our data provide no contra-indication for nutritional intake of plant sterol enriched nutrition

Soziale Integration und Politische Institutionen in Modernen Gesellschaften

Im Unterschied zu zeitgenössischen Diagnosen über den Zustand moderner Gesellschaften, geht die Analyse davon aus, daß die These der Desintegration dieser Gesellschaften empirisch völlig ungeklärt ist. Zur Durchführung von systematischen und empirischen Studien sind allererst begrifflich-theoretische Vorarbeiten nötig, zu denen die Analyse beitragen will. Es werden drei Ziele verfolgt: Erstens eine genaue Bestimmung des Begriffs der sozialen Integration. Dazu werden sechs operationale Definitionen vorgeschlagen, die sich unter anderem im Grad ihres normativen Anspruchs unterscheiden. Zweitens eine genaue Bestimmung des Begriffs der politischen Institutionen und drittens die Spezifikation eines empirisch testbaren liberalen Modells der sozialen Integration. In diesem Modell spielt die Unterstützung des politischen Institutionengefüges eines Landes eine zentrale Rolle. Die Konstruktion des Modells orientiert sich an der grundlegenden Unterscheidung eines politischen Systems in drei hierarchisch angeordnete Ebenen ' der Kultur-, Struktur- und Prozeßebene ' und konkretisiert diese Ebenen in Anlehnung an die liberale Demokratietheorie durch die Spezifikation von empirisch meßbaren Konstrukten und Zusammenhängen zwischen diesen Konstrukten.In contrast to contemporary diagnoses of the state of modern societies, this analysis assumes that the thesis of the disintegration of these societies is not empirically established at all. Systematic empirical studies require preliminary conceptual work to which this analysis contributes. The analysis sets itself three goals: firstly, it proposes a precise definition of the concept of social integration in terms of six operational definitions with different normative standards. Secondly, it suggests an accurate definition of the concept of political institutions and, thirdly, it specifies an empirically testable liberal model of social integration. In this model, support of the institutional structure of a country plays a central role. The model differentiates three levels-cultural, structural, and procedural- operationalizing them in a concrete form following liberal democratic theory. Empirically testable interrelations between the constructs are specified

Importance of cross-channel bathymetry and eddy viscosity parameterisation in modelling estuarine flow

For a proper understanding of flow patterns in curved tidal channels, quantification of contributions from individual physical mechanisms is essential. We study quantitatively how such contributions are affected by crosschannel bathymetry and three alternative eddy viscosity parameterisations. Two models are presented for this purpose, both describing flow in curved but otherwise prismatic channels with an (almost) arbitrary transverse bathymetry. One is a numerical model based on the full threedimensional shallow water equations. Special feature of this diagnostic model is that assumptions regarding the relative importance of particular physical mechanisms can be incorporated in the computations by switching corresponding terms in the model equations on or off. We also present an idealized model that provides semi-analytical approximate solutions of the shallow water equations for all three considered alternative eddy viscosity parameterisations. It forms an aid in explaining and theorising about results obtained with the numerical model. Observations regarding Chesapeake Bay serve as a reference case for the present study. We find that the relative importance of both along channel advective forcing and transverse diffusive forcing depends on local characteristics of the cross-sectional bottom profile rather than global ones. In our reference case, tide-residual along-channel flow induced by these forcings is not small compared to the total tidal residual. Building on this observation, we present an indicative test to judge whether advective processes should be included in leading order in modelling tide-dominated estuarine flow. Furthermore, depending on the applied eddy viscosity parameterisation (uniformly or parabolically distributed over the vertical), we find qualitatively different spatial patterns for the along-channel advective forcing.Hydraulic EngineeringCivil Engineering and Geoscience