University of Graz

About: University of Graz is a education organization based out in Graz, Steiermark, Austria. It is known for research contribution in the topics: Population & Context (language use). The organization has 17934 authors who have published 37489 publications receiving 1110980 citations. The organization is also known as: Carolo Franciscea Graecensis & Karl Franzens Universität.

In Vitro Biofilm Formation of Commensal and Pathogenic Escherichia coli Strains: Impact of Environmental and Genetic Factors

Abstract: Our understanding of Escherichia coli biofilm formation in vitro is based on studies of laboratory K-12 strains grown in standard media. However, pathogenic E. coli isolates differ substantially in their genetic repertoire from E. coli K-12 and are subject to heterogeneous environmental conditions. In this study, in vitro biofilm formation of 331 nondomesticated E. coli strains isolated from healthy (n = 105) and diarrhea-afflicted children (n = 68), bacteremia patients (n = 90), and male patients with urinary tract infections (n = 68) was monitored using a variety of growth conditions and compared to in vitro biofilm formation of prototypic pathogenic and laboratory strains. Our results revealed remarkable variation among the capacities of diverse E. coli isolates to form biofilms in vitro. Notably, we could not identify an association of increased biofilm formation in vitro with a specific strain collection that represented pathogenic E. coli strains. Instead, analysis of biofilm data revealed a significant dependence on growth medium composition (P < 0.05). Poor correlation between biofilm formation in the various media suggests that diverse E. coli isolates respond very differently to changing environmental conditions. The data demonstrate that prevalence and expression of three factors known to strongly promote biofilm formation in E. coli K-12 (F-like conjugative pili, aggregative adherence fimbriae, and curli) cannot adequately account for the increased biofilm formation of nondomesticated E. coli isolates in vitro. This study highlights the complexity of genetic and environmental effectors of the biofilm phenotype within the species E. coli.

Gene expression of the key enzymes of melatonin synthesis in extrapineal tissues of the rat.

Abstract: Besides the pineal gland, melatonin is reported to be produced in a number of extrapineal sites, where it could act as an intracellular mediator or paracrine signal in addition to its endocrine effects. In view of the suggested immunoregulatory role of melatonin, we compared lymphoid organs and several other tissues of the rat for their potential to synthesize melatonin. Using the reverse transcription-polymerase chain reaction (RT-PCR) method, we determined the tissue-specific expression of mRNAs encoding two key enzymes of the melatonin biosynthesis: serotonin-N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT). The minimal number of PCR cycles required to obtain a positive signal served as a measure for the abundance of a given mRNA. NAT and HIOMT mRNAs were detected in all tested tissues at high numbers of PCR cycles (40 and 45, respectively). At 35 cycles, only gut, testis, spinal cord, raphe nuclei, stomach fundus and striatum yielded positive signals for both enzymes. In conclusion, the presence of NAT and HIOMT mRNAs in a wide range of tissues corroborates and extends the notion of extrapineal melatonin synthesis. Comparatively low levels of the HIOMT messages in lymphoid organs, however, indicate a limited significance of melatonin synthesis within the immune system.

Kontrolliertes Erhitzen mit Mikrowellen in der modernen organischen Synthese

Abstract: Die offene Flamme konnte erst gezielt als Heizquelle fur Reaktionsgefase in der Synthesechemie verwendet werden, nachdem Robert Bunsen 1855 den nach ihm benannten Brenner erfunden hatte. Der Bunsen-Brenner wurde spater durch den Heizpilz, das Olbad und die Heizplatte als Warmequellen fur chemische Reaktionen abgelost. In den vergangenen Jahren ist das Erhitzen und Beschleunigen chemischer Reaktionen durch Mikrowellenenergie popular geworden. Diese Heiztechnik hat sich von einer Laborkuriositat zu einer etablierten Methode entwickelt, die an Universitaten und in der Industrie stark genutzt wird. Die effiziente Verringerung der Reaktionszeiten (von Tagen und Stunden auf Minuten und Sekunden) ist nur einer der vielen Vorteile des schnellen Erhitzens mit Mikrowellen (“microwave flash heating”). Dieser Aufsatz gibt einen Uberblick uber neuere Anwendungen des kontrollierten Mikrowellenerhitzens in der modernen organischen Synthese und diskutiert einige grundlegende Vorgange.

Magnetic resonance signal abnormalities in asymptomatic individuals: their incidence and functional correlates.

Abstract: MR signal abnormalities were assessed in 87 symptom-free volunteers (31–83 years of age) and correlated with cerebrovascular risk factors, cerebral blood flow and glucose metabolism. Lesions in the su