Listeria pathogenesis and molecular virulence determinants

The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Clinical manifestations of invasive listeriosis are usually severe and include abortion, sepsis, and meningoencephalitis. Listeriosis can also manifest as a febrile gastroenteritis syndrome. In addition to humans, L. monocytogenes affects many vertebrate species, including birds. Listeria ivanovii, a second pathogenic species of the genus, is specific for ruminants. Our current view of the pathophysiology of listeriosis derives largely from studies with the mouse infection model. Pathogenic listeriae enter the host primarily through the intestine. The liver is thought to be their first target organ after intestinal translocation. In the liver, listeriae actively multiply until the infection is controlled by a cell-mediated immune response. This initial, subclinical step of listeriosis is thought to be common due to the frequent presence of pathogenic L. monocytogenes in food. In normal indivuals, the continual exposure to listerial antigens probably contributes to the maintenance of anti-Listeria memory T cells. However, in debilitated and immunocompromised patients, the unrestricted proliferation of listeriae in the liver may result in prolonged low-level bacteremia, leading to invasion of the preferred secondary target organs (the brain and the gravid uterus) and to overt clinical disease. L. monocytogenes and L. ivanovii are facultative intracellular parasites able to survive in macrophages and to invade a variety of normally nonphagocytic cells, such as epithelial cells, hepatocytes, and endothelial cells. In all these cell types, pathogenic listeriae go through an intracellular life cycle involving early escape from the phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin-based motility, and direct spread to neighboring cells, in which they reinitiate the cycle. In this way, listeriae disseminate in host tissues sheltered from the humoral arm of the immune system. Over the last 15 years, a number of virulence factors involved in key steps of this intracellular life cycle have been identified. This review describes in detail the molecular determinants of Listeria virulence and their mechanism of action and summarizes the current knowledge on the pathophysiology of listeriosis and the cell biology and host cell responses to Listeria infection. This article provides an updated perspective of the development of our understanding of Listeria pathogenesis from the first molecular genetic analyses of virulence mechanisms reported in 1985 until the start of the genomic era of Listeria research

Solarthermie 2000. Teilprogramm 3: Solar unterstuetzte Nahwaermeversorgung Pilotanlage Chemnitz Forschungsbericht

In this project, solar-supported district heating systems were designed, constructed and monitored between 1993 and 2002. Key issues were feasibility, proof os cost reduction in industrial-scale systems, further development, and technical analyses. The project documented in this report had the following parameters: a) Energy source: Solar collector fields with an absorber surface of 538.5 m"2 (evacuated tube collectors) and cogeneration units. b) Seasonal storage: 8000 m"3 gravel-water store. c) Loads: Heating system of an office building. The authors accompanied the project by scientific and technical investigations. Results are presented on system performance and component and system efficiencies. (orig.)Im Forschungs- und Demonstrationsprogramm Solarthermie 2000, Teilprogramm 3 wurden von 1993 bis 2002 solar unterstuetzte Nahwaermesysteme konzipiert, errichtet und vermessen. Wesentliche Ziele dieses Programms waren die Demonstration der Durchfuehrbarkeit, der Nachweis der Kostenreduktion bei grossen Systemen und die Weiterentwicklung sowie Untersuchung dieser Technik. Das in diesem Bericht dokumentierte Forschungsvorhaben ist ein Projekt in oben genanntem Vorhaben und zeichnet sich durch folgende Parameter aus: a. Energiequelle: Kollektorfelder mit einer Absorberflaeche von 538,5 m"2 (Vakuum-Roehrenkollektoren) und BHKW, b. saisonaler Speicher: 8000 m"3 Kies-Wasser-Speicher, c. Verbraucher: Heizung eines Buerogebaeudes. Das Vorhaben wurde durch die Autoren wissenschaftlich-technisch betreut. Die Erkenntnisse von der Konzeption bis zur funktionstuechtigen Anlage werden im Bericht erlaeutert. Auf Grund der messtechnischen Untersuchung liegen detaillierte Ergebnisse zum Systemverhalten, zur Effizienz der Bauteile und des Systems vor. (orig.)SIGLEAvailable from TIB Hannover: F03B1534 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Solarthermie 2000. Teilprogramm 2: Musterstatiken fuer tragende Aufstellkonstruktionen von thermischen Solaranlagen auf Flachdaechern Abschlussbericht

The target of the project is, to lower the costs of the basic constructions and the costs of the static calculation. These costs categories develop when setting up collectors on flat roofs. Cost-optimized solutions are presented beginning with the attachment detail up to the carrying construction. A economical implementation enables. A substantial point of the project is the examination of the load assumptions, particularly the wind load. Result is a modular system, which gives a selection of attachment details depending upon available roof structure and a combination of different carrying constructions co-ordinated with most frequently occurring collector types enables. (orig.)Das Ziel des Projektes ist, sowohl die Kosten fuer die Unterkonstruktion als auch die Kosten fuer die statische Berechnung, die fuer eine Aufstaenderung von Kollektoren auf flachen Daechern notwendig sind, zu senken. Dazu werden kostenoptimierte Loesungen fuer Aufstaenderungssysteme vom Befestigungsdetail bis zur Tragkonstruktion vorgestellt, die eine kostenguenstige Realisierung ermoeglichen. Ein wesentlicher Bestandteil des Vorhabens ist die Ueberpruefung der Lastannahmen insbesondere der Windlast. Resultat ist ein modulares System, das, je nach vorliegender Dachkonstruktion, eine Auswahl von Befestigungsdetails vorgibt und eine Kombination verschiedener Tragkonstruktionen mit den gebraeuchlichsten Kollektortypen und -feldgroessen ermoeglicht. (orig.)Published in 2 separate volumesSIGLEAvailable from TIB Hannover: F01B1766(1): F01B1766(2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Methodology for EBSILON simulation studies of on-site generation CHP systems for data centre

The use of information technology services is increasing and causes a rising energy demand of data centres. In order to cover the requirements linked to this effect and respond to the energetic and environmental goals, fossil fuels need to be replaced by renewable energy sources, and methods to increase the efficiency of the processes have to be developed. Regarding the energy supply of data centres, the complex integration of different energy systems into the technical infrastructure of the data centres is challenging. Within the RenewIT project [1], fourteen thermal and electrical power supply concepts for data centres have been investigated [2]. Regarding intermediate results of the project, the four concepts with combined heat and power production (CHP) provide the most promising solutions. One of the concepts with CHP, the system biogas-fed solid oxide fuel cell (SOFC), is presented to show the methodology of modelling and simulating the CHP subsystem including non-series products with EBSILON [3]. The complex part load behaviour of the subsystem is identified and the information is transferred into TRNSYS [4] to increase data processing and minimize computing time.Postprint (published version

Methodology for EBSILON simulation studies of on-site generation CHP systems for data centre

The use of information technology services is increasing and causes a rising energy demand of data centres. In order to cover the requirements linked to this effect and respond to the energetic and environmental goals, fossil fuels need to be replaced by renewable energy sources, and methods to increase the efficiency of the processes have to be developed. Regarding the energy supply of data centres, the complex integration of different energy systems into the technical infrastructure of the data centres is challenging. Within the RenewIT project [1], fourteen thermal and electrical power supply concepts for data centres have been investigated [2]. Regarding intermediate results of the project, the four concepts with combined heat and power production (CHP) provide the most promising solutions. One of the concepts with CHP, the system biogas-fed solid oxide fuel cell (SOFC), is presented to show the methodology of modelling and simulating the CHP subsystem including non-series products with EBSILON [3]. The complex part load behaviour of the subsystem is identified and the information is transferred into TRNSYS [4] to increase data processing and minimize computing time