Morphological and functional characterisation of a new murine serum-free in vitro model of the blood-brain barrier

Die Blut-Hirn Schranke stellt eine Barriere dar, die den Durchtritt von Substanzen aus dem Blut in das Gehirn kontrolliert. In vitro-Modelle der Blut-Hirn Schranke können dabei helfen, die regulatorischen Vorgänge an dieser Barriere zu verstehen und gegebenenfalls die Behand-lung von Erkrankungen wie dem Kreuzfeld-Jakob-Syndrom, Alzheimer oder Multiple Sclerose zu verbessern. In der vorliegenden Arbeit wird ein serum-freies in vitro-Modell vorgestellt, dass auf murinen Endothelzellen aus den cerebralen Kapillaren basiert. Es konnte gezeigt werden, dass Hydrocortison in physiologischen Konzentrationen die Barriereeigen-schaften dDer Zellen verstärkt und so zu der Integrität der Barriere unter den serumfreien Bedingungen beiträgt. Es lassen sich dabei Veränderungen am Aktinzytoskelett festellen, die mit Änderungen der mechanischen Eigenschaften und des transendothelialen elektrischen Widerstandes (TEER) der Zellen einhergehen. Hydrocortison verstärkt den TEER, wobei sowohl eine Veränderung im Zell-Substrat-Kontakt sowie im Zell-Zellkontakt detektiert werden kann

In Vitro Study of the Effects of Angiostrongylus cantonensis Larvae Extracts on Apoptosis and Dysfunction in the Blood-Brain Barrier (BBB)

It has been hypothesized that blood-brain barrier (BBB) dysfunction in Angiostrongylus cantonensis infection might be due to the apoptosis of the hosts' BBB cells. Here, we evaluated this hypothesis through several methods, all based on an in vitro mouse BBB model consisting of primary culture brain microvascular endothelial cells (BMECs) and brain astrocytic cells (BACs). In the present study, a four-hour percolation and HRP permeability experiment showed that A. cantonensis larvae extracts can increase the permeability of the BBB. Apoptosis among BMECs and BACs after exposure to larvae extracts was monitored by TUNEL and annexin-V-FITC/PI double staining. A. cantonensis larvae extracts were found to induce apoptosis in both BMECs and BACs. For this reason, we concluded that the induction of apoptosis might participate in the BBB dysfunction observed during angiostrongyliasis. Improved fundamental understanding of how A. cantonensis induces apoptosis may lead to new approaches to the treatment or prevention of this parasitic disease

A β-Lactam Antibiotic Dampens Excitotoxic Inflammatory CNS Damage in a Mouse Model of Multiple Sclerosis

In multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), impairment of glial “Excitatory Amino Acid Transporters” (EAATs) together with an excess glutamate-release by invading immune cells causes excitotoxic damage of the central nervous system (CNS). In order to identify pathways to dampen excitotoxic inflammatory CNS damage, we assessed the effects of a β-lactam antibiotic, ceftriaxone, reported to enhance expression of glial EAAT2, in “Myelin Oligodendrocyte Glycoprotein” (MOG)-induced EAE. Ceftriaxone profoundly ameliorated the clinical course of murine MOG-induced EAE both under preventive and therapeutic regimens. However, ceftriaxone had impact neither on EAAT2 protein expression levels in several brain areas, nor on the radioactive glutamate uptake capacity in a mixed primary glial cell-culture and the glutamate-induced uptake currents in a mammalian cell line mediated by EAAT2. Moreover, the clinical effect of ceftriaxone was preserved in the presence of the EAAT2-specific transport inhibitor, dihydrokainate, while dihydrokainate alone caused an aggravated EAE course. This demonstrates the need for sufficient glial glutamate uptake upon an excitotoxic autoimmune inflammatory challenge of the CNS and a molecular target of ceftriaxone other than the glutamate transporter. Ceftriaxone treatment indirectly hampered T cell proliferation and proinflammatory INFγ and IL17 secretion through modulation of myelin-antigen presentation by antigen-presenting cells (APCs) e.g. dendritic cells (DCs) and reduced T cell migration into the CNS in vivo. Taken together, we demonstrate, that a β-lactam antibiotic attenuates disease course and severity in a model of autoimmune CNS inflammation. The mechanisms are reduction of T cell activation by modulation of cellular antigen-presentation and impairment of antigen-specific T cell migration into the CNS rather than or modulation of central glutamate homeostasis

Astrocytes: biology and pathology

Astrocytes are specialized glial cells that outnumber neurons by over fivefold. They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS. Astrocytes respond to all forms of CNS insults through a process referred to as reactive astrogliosis, which has become a pathological hallmark of CNS structural lesions. Substantial progress has been made recently in determining functions and mechanisms of reactive astrogliosis and in identifying roles of astrocytes in CNS disorders and pathologies. A vast molecular arsenal at the disposal of reactive astrocytes is being defined. Transgenic mouse models are dissecting specific aspects of reactive astrocytosis and glial scar formation in vivo. Astrocyte involvement in specific clinicopathological entities is being defined. It is now clear that reactive astrogliosis is not a simple all-or-none phenomenon but is a finely gradated continuum of changes that occur in context-dependent manners regulated by specific signaling events. These changes range from reversible alterations in gene expression and cell hypertrophy with preservation of cellular domains and tissue structure, to long-lasting scar formation with rearrangement of tissue structure. Increasing evidence points towards the potential of reactive astrogliosis to play either primary or contributing roles in CNS disorders via loss of normal astrocyte functions or gain of abnormal effects. This article reviews (1) astrocyte functions in healthy CNS, (2) mechanisms and functions of reactive astrogliosis and glial scar formation, and (3) ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions

Particulate Fillers in Thermoplastics

The characteristics of particulate filled thermoplastics are determined by four factors: component properties, composition, structure and interfacial interactions. The most important filler characteristics are particle size, size distribution, specific surface area and particle shape, while the main matrix property is stiffness. Segregation, aggregation and the orientation of anisotropic particles determine structure. Interfacial interactions lead to the formation of a stiff interphase considerably influencing properties. Interactions are changed by surface modification, which must be always system specific and selected according to its goal. Under the effect of external load inhomogeneous stress distribution develops around heterogeneities, which initiate local micromechanical deformation processes determining the macroscopic properties of the composites

Unterpliozäne Schwemmfächerablagerungen und Silikrete am Südrand des Rheinischen Schiefergebirges bei Gutenberg und Wallhausen (Tertiär / Unteres Nahehügelland, Rheinland-Pfalz, Deutschland)

Im Grenzbereich der Gemarkungen von Gutenberg und Wallhausen (Rheinland- Pfalz, SW-Deutschland) werden seit vielen Jahrzehnten Kiese abgebaut, deren Genese und stratigraphische Stellung bislang ungenügend untersucht sind. Zur Klärung der Lagerungsverhältnisse wurden in dem Bereich zwei Profile aufgenommen und nach sedimentologischen und lithostratigraphischen Kriterien bearbeitet. In den Profilen können jeweils vier übereinander geschüttete Fining-upward- (FU 1 bis 4) und zwei darüber abgelagerte Coarsening-upward-Zyklen (CU 1 bis 2) unterschieden werden, die ausschließlich aus lokalen Komponenten aufgebaut werden und Ablagerungen eines kleinen Schwemmfächers darstellen. Die Genese des Schwemmfächers wird als Folge einer schwachen Anhebung des Hinterlands nördlich der Hunsrück-Südrand- Störung interpretiert. In beiden Profilen treten im Grenzbereich CU 1 / CU 2 Silikrete auf, die als Gutenberg-Bank bezeichnet werden. Nur im höheren Teil von FU 2 wurden zudem in beiden Profilen Saprolitgerölle nachgewiesen. Aufgrund der Zyklizität, der Silikretbildung und des Saprolitgeröllhorizontes können beide Profile korreliert werden. Die Schwemmfächerablagerungen sind aufgrund lithostratigraphischer und paläoklimatologischer Überlegungen sehr wahrscheinlich im tieferen Zancleum gebildet worden, die Silikretbildung wird in das mittlere Zancleum (4,3 bis 4,6 Ma) eingestuft.Abstract: In the border area of Gutenberg and Wallhausen (Rheinland-Pfalz, SW-Germany), gravel deposits have been mined for many decades. Nevertheless the genesis and stratigraphic position of them have not been sufficiently investigated so far. To clarify the bedding conditions, two sections were studied using sedimentological and stratigraphic methods. In both sections four superimposed fining-upward cycles (FU 1 to FU 4) and two coarsening-upward cycles (CU 1 and CU 2) are differentiated, which consist of local detritus and are interpreted as alluvial fan deposits. The formation of the small alluvial fan is interpreted as a consequence of a minor uplift pulse of the hinterland north of the South Hunsrück fault. Silicretes occur at the CU 1 / CU 2 boundary, which are named Gutenberg bed hereby. In the higher section of FU 2 saprolite pebbles are present. The two sections are correlated based on their cyclicity, the silicrete layer and the saprolite gravel beds. By considering lithostratigraphy and paleoclimate, the alluvial fan most likely formed in the lower Zanclean. The formation of the silicretes is correlated to the middle Zanclean (4.3 to 4.6 Ma).researc

The Heidelberg Drilling Project (Upper Rhine Graben, Germany)

The Heidelberg basin hosts one of the thickest successions of unconsolidated Pliocene and Quaternary deposits in continental middle Europe, and certainly the thickest succession built by the Geosystem Rhine, connecting Alps, Rhine Graben, North Sea and English Channel. Also local Geosystems, first place the Neckar System, contribute to the basin infill. The more or less continuous subsidence of the Upper Rhine Graben (URG) during all periods of tertiary Graben history, but especially during the last few million years, led to a succession of alternating fluvial and lacustrine environments of various provenances. This archive contains not only various proxies of the mid-European climate evolution during the Plio-Quaternary, but also signals of geodynamic processes controlled by tectonics. Various pre project activities during the last years prove the feasibility of an extensive research project to begin in late 2005. In its centre will be three drillings envisaged to become 300 m, 350 m and 500 m deep which are all designed to expose the Plio-Quaternary transition. The various techniques of facies analysis, geophysical exploration, geochronology, climate and tectonics modelling, to be combined in a comprehensive 3D evolutionary scenario, will – hopefully – enable us to read and understand the archive of the Heidelberg basin fill. The expected results will not only contribute to the data pools of palaeoclimate and neotectonics, but are also a methodological test in handling complex Geosystems. A considerable fallout with regard to societal use and handling of the geo-environment is also expected: from use of geothermal energy, hydrogeology and pollution handling in a highly industrialized region, right to assessment of climate and seismic risks.The project will be run by a Co-operation of the Leibniz Institute for Applied Geosciences (Hannover) and the Geological Services of the three German federal States sharing the territories of the Heidelberg basin (Baden-Württemberg, Hessen, Rheinland-Pfalz). This paper is designed to outline the project, present some very preliminary results of pre-project research and stimulate further collaboration into the main project to come.Le bassin d’Heidelberg présente une des successions de dépôts quaternaires non consolidés les plus épaisses d’Europe continentale moyenne et certainement la succession la plus épaisse du géosystème Rhin, connectant les Alpes, le graben du Rhin, la Mer du Nord et la Manche. Des géosystèmes locaux, avec en premier lieu celui du Neckar, contribuent également au remplissage du bassin. La subsidence plus ou moins continue de cette partie du graben du Rhin durant toute son histoire cénozoïque, mais en particulier durant les derniers millions d’années, a conduit à la mise en place d’une succession d’environnements fluviaux et lacustres de différentes provenances. Cette archive ne contient pas seulement différents proxies de l’évolution climatique durant le Plio-Quaternaire, mais également des signaux des processus géodynamiques controlés par le climat et la tectonique.Différentes activités pré-projet menées durant ces dernières années ont montré la faisabilité d’un programme de recherche important qui a pris corps autour d’un projet de carottage profond prévue pour commencer à la fin 2005. Les différentes techniques d’analyse de faciès, d’exploration géophysique, de géochronologie, de modélisation du climat et de la tectonique, prévues pour être intégrées dans un modèle compréhensif d’évolution 3D, permettront de lire et de comprendre l’archive d’Heidelberg. Les résultats escomptés ne contribueront pas seulement à documenter les aspects paléoclimatiques et néotectoniques, mais fourniront également un apport méthodologique pour l´appréhension des géosystèmes complexes. Des retombées importantes sont également attendues par rapport aux usages sociaux et à la gestion des géo-environnements, en ce qui concerne l’énergie géothermique, l’hydrogéologie et la maîtrise des pollutions dans une région très industrialisée, sensible aux modifications climatiques et au risque sismique.Le projet sera mis en œuvre grâce à une coopération de l’Institut GGA pour les Géosciences appliquées de Hanovre et les services géologiques des trois Länder recouvrant le bassin d’Heidelberg (Baden-Württemberg, Hesse, Rhénanie-Palatinat). Cet article expose le projet, présente quelques résultats préliminaires ou recherches pré-projets et propose des opportunités de collaboration