Hyaluronan Export through Plasma Membranes Depends on Concurrent K+ Efflux by Kir Channels

Hyaluronan is synthesized within the cytoplasm and exported into the extracellular matrix through the cell membrane of fibroblasts by the MRP5 transporter. In order to meet the law of electroneutrality, a cation is required to neutralize the emerging negative hyaluronan charges. As we previously observed an inhibiting of hyaluronan export by inhibitors of K+ channels, hyaluronan export was now analysed by simultaneously measuring membrane potential in the presence of drugs. This was done by both hyaluronan import into inside-out vesicles and by inhibition with antisense siRNA. Hyaluronan export from fibroblast was particularly inhibited by glibenclamide, ropivacain and BaCl2 which all belong to ATP-sensitive inwardly-rectifying Kir channel inhibitors. Import of hyaluronan into vesicles was activated by 150 mM KCl and this activation was abolished by ATP. siRNA for the K+ channels Kir3.4 and Kir6.2 inhibited hyaluronan export. Collectively, these results indicated that hyaluronan export depends on concurrent K+ efflux

Hantaviren und Nagetiere in Deutschland: Das Netzwerk „Nagetier-übertragene Pathogene”

ZusammenfassungHantavirus-Infektionen sind in Deutschland seit etwa 25 Jahren bekannt. Die durchschnittliche Antikörperprävalenz in der Bevölkerung liegt bei ca. 1 bis 2%. Nach Einführung der Meldepflicht im Jahr 2001 sind jährlich durchschnittlich etwa 70 bis 240 Fälle gemeldet worden. Im Jahr 2005 und insbesondere im Jahr 2007 ist jedoch ein deutlicher Anstieg der Zahl der gemeldeten Fälle registriert worden. Die am meisten betroffenen Regionen lagen in den Bundesländern Baden-Württemberg, Bayern, Nordrhein-Westfalen und Niedersachsen. Im Gegensatz zur gut dokumentierten Situation beim Menschen ist die Kenntnis der geografischen Verbreitung und Häufigkeit von Hantavirus-Infektionen in den Nagetier-Reservoiren und deren Schwankungen sehr begrenzt. Aus diesem Grund wurde in Deutschland das Netzwerk „Nagetier-übertragene Pathogene“ etabliert, das interdisziplinäre Untersuchungen zur Nagetier-Populationsdynamik, Prävalenz und Evolution von Hantaviren und anderen Nagetier-assoziierten Zoonoseerregern und den zugrunde liegenden Mechanismen sowie deren Auswirkungen auf die Häufigkeit humaner Infektionen erlaubt. Ein Monitoring von Hantaviren in Nagetieren wurde in Endemiegebieten (Baden-Württemberg, Bayern, Nordrhein-Westfalen, Niedersachsen) und Regionen mit einer geringen Zahl humaner Fälle (Mecklenburg-Vorpommern, Brandenburg, Sachsen, Sachsen-Anhalt, Thüringen, Schleswig-Holstein, Hessen, Rheinland-Pfalz) initiiert. Insgesamt wurde eine breite geographische Verbreitung des Puumalavirus (PUUV) in Rötelmäusen und des Tulavirus in Microtus-Mäusen dokumentiert. Dobrava-Belgrad-Virus-positive Apodemus-Mäuse wurden bisher ausschließlich in Brandenburg, Mecklenburg-Vorpommern und Niedersachsen gefunden. In den Hantavirus-Ausbruchsgebieten in Baden-Württemberg, Bayern, Nordrhein-Westfalen und Niedersachsen wurde bei Rötelmäusen eine hohe PUUV-Prävalenz beobachtet. Initiale Longitudinalstudien in Nordrhein-Westfalen (Stadt Köln), Bayern (Niederbayern) und Niedersachsen (ländliche Region bei Osnabrück) zeigten ein stabiles Vorkommen des PUUV in den Rötelmaus-Populationen. Neben den Untersuchungen zu Hantaviren ist auch mit Studien zum Vorkommen von anderen Nagetier-assoziierten Zoonoseerregern begonnen worden. Die begonnenen Longitudinalstudien werden Schlussfolgerungen zur Evolution von Hantaviren und anderen Nagetierassoziierten Erregern und zu Veränderungen in deren Häufigkeit und Verbreitung ermöglichen. Diese Untersuchungen werden zukünftig eine verbesserte Risikoabschätzung für die Gefährdung der Bevölkerung ermöglichen, die auch die möglichen zukünftigen Klimawandel-bedingten Veränderungen in der Epidemiologie Nagetier-assoziierter Zoonoseerreger berücksichtigt

Reviewing the use of resilience concepts in forest sciences

Purpose of the review Resilience is a key concept to deal with an uncertain future in forestry. In recent years, it has received increasing attention from both research and practice. However, a common understanding of what resilience means in a forestry context, and how to operationalise it is lacking. Here, we conducted a systematic review of the recent forest science literature on resilience in the forestry context, synthesising how resilience is defined and assessed. Recent findings Based on a detailed review of 255 studies, we analysed how the concepts of engineering resilience, ecological resilience, and social-ecological resilience are used in forest sciences. A clear majority of the studies applied the concept of engineering resilience, quantifying resilience as the recovery time after a disturbance. The two most used indicators for engineering resilience were basal area increment and vegetation cover, whereas ecological resilience studies frequently focus on vegetation cover and tree density. In contrast, important social-ecological resilience indicators used in the literature are socio-economic diversity and stock of natural resources. In the context of global change, we expected an increase in studies adopting the more holistic social-ecological resilience concept, but this was not the observed trend. Summary Our analysis points to the nestedness of these three resilience concepts, suggesting that they are complementary rather than contradictory. It also means that the variety of resilience approaches does not need to be an obstacle for operationalisation of the concept. We provide guidance for choosing the most suitable resilience concept and indicators based on the management, disturbance and application context

Tissue-Engineering approaches for central and peripheral nervous-system regeneration.

The nervous system of the human body can be divided into two parts: the central and the peripheral nervous system. While the central nervous system (CNS) includes the brain and the spinal cord, the peripheral nervous system (PNS) consists of all the nerve branches exiting the spinal cord or brain stem that process information from our environment to the CNS and vice versa. The main extension that passes all incoming information to the next neuron or a peripheral target is called an axon. Axons can be as long as 1 meter, as in the case of axons sending electrical signals to the toes. All incoming information is received by smaller structures called dendrites. Axons are wrapped with glial cells, Schwann cells in the PNS, and oligodendrocytes in the CNS. These cells are responsible for the deposition of myelin, a powerful insulator. Each glial cell is covering an axonal segment of about 1-2 mm. An unmyelinated gap separates two glial cells. Action potentials are generated at those gaps. This electrical signal jumps from one unmyelinated gap to the next, giving rise to conduction velocities as fast as 1 m/s. In the PNS, axons are grouped together into fascicles, consisting of a layer of connective tissue surrounding bundles of axons. Several of these fascicles form a peripheral nerve surrounded by another connective tissue layer named epineurium. The epineurium is responsible for the integrity of the overall structure of a peripheral nerve. While the PNS shows regenerative capabilities, this is in general not the case for the CNS. The mechanisms explaining the poor regeneration capabilities of the CNS have started to be elucidated. The expression of inhibitory molecules in the mammalian-adult nervous system seems to be an essential component in the inherent lack of CNS regeneration. Examples for possible applications of materials systems addressing certain issues of PNS and CNS regeneration are presented in the following sections.</jats:p