Comparative genomics of Escherichia coli isolated from patients with inflammatory bowel disease

<p>Abstract</p> <p>Background</p> <p>Inflammatory bowel disease (IBD) is used to describe a state of idiopathic, chronic inflammation of the gastrointestinal tract. The two main phenotypes of IBD are Crohn's disease (CD) and ulcerative colitis (UC). The major cause of IBD-associated mortality is colorectal cancer. Although both host-genetic and exogenous factors have been found to be involved, the aetiology of IBD is still not well understood. In this study we characterized thirteen <it>Escherichia coli </it>strains from patients with IBD by comparative genomic hybridization employing a microarray based on 31 sequenced <it>E. coli </it>genomes from a wide range of commensal and pathogenic isolates.</p> <p>Results</p> <p>The IBD isolates, obtained from patients with UC and CD, displayed remarkably heterogeneous genomic profiles with little or no evidence of group-specific determinants. No IBD-specific genes were evident when compared with the prototypic CD isolate, LF82, suggesting that the IBD-inducing effect of the strains is multifactorial. Several of the IBD isolates carried a number of extraintestinal pathogenic <it>E. coli </it>(ExPEC)-related virulence determinants such as the <it>pap</it>, <it>sfa</it>, <it>cdt </it>and <it>hly </it>genes. The isolates were also found to carry genes of ExPEC-associated genomic islands.</p> <p>Conclusions</p> <p>Combined, these data suggest that <it>E. coli </it>isolates obtained from UC and CD patients represents a heterogeneous population of strains, with genomic profiles that are indistinguishable to those of ExPEC isolates. Our findings indicate that IBD-induction from <it>E. coli </it>strains is multifactorial and that a range of gene products may be involved in triggering the disease.</p

Calculated energy performance certificate of a duplex house and energy renovation analysis

V diplomski nalogi je predstavljena izdelava računske energetske izkaznice s poudarkom na priporočilih za energetsko sanacijo dvostanovanjske stavbe, locirane v Medvodah. Stavba je bila zgrajena leta 1985. V tem obdobju se je začela uporabljati toplotna izolacija, saj so se že pojavljala vprašanja o energetski učinkovitosti stavb. Energetska izkaznica stavb je potrebna pri prodaji in najemu stavbe, če je obdobje najema daljše od enega leta. Obvezna je tudi pri novogradnji kot del projekta izvedenih del. V uvodnem delu sem predstavil veljavno zakonodajo, ki ureja področje učinkovite rabe energije v stavbah. Potem sem s pomočjo programa TEDI in TOST izdelal računsko energetsko izkaznico za obravnavani objekt v obstoječem stanju, nato pa sem se osredotočil na učinkovitost posameznega ukrepa energetske sanacije. Pri vsakem ukrepu sem komentiral dobljene rezultate in se odločil o smiselnosti njegove izvedbe v odvisnosti od tehnične zahtevnosti in posledičnega prihranka energije. Pri obravnavani stavbi se največ energije, potrebne za ogrevanje z menjavo transparentnega dela in mehanskim prezračevanjem, prihrani z vračanjem toplote odpadnega zraka, in sicer blizu 50 %. Z izborom vseh ukrepov, za katere menim, da so smiselni, pa se prihrani preko 80 % potrebne letne toplote za ogrevanje stavbe. Tudi koeficient specifičnih transmisijskih izgub se zmanjša za 60 %. Poveča pa se potreba po hlajenju, kar je tipična stranska škoda zelo dobro toplotno izoliranih stavb. V zaključnem delu so predstavljene ugotovitve, nastale tekom diplomske naloge.In the undergraduate thesis, the production of the calculated energy performance certificate for the specific building is undertaken. This is done with the emphasis on recommendations for energy renovation of the duplex residential building, which is located in Medvode, Slovenia and was built in 1985. When the building was constructed, energy efficiency was already gaining importance. Consequently many buildings constructed in this period were moderately thermally insulated. An energy performance certificate is legally required when a building is offered for purchase and when it is leased for a period longer than one year. Furthermore the certificate is mandatory for newly built properties, as a basic requirement for the project plan. The thesis initially examines the current legislation, which regulates the area of energy efficiency in buildings. Next the energy performance for the considered building will be produced. This will be done with TEDI and TOST computer software. After that, individual technical measures will be analysed. The viability of these measures will be assessed in consideration of technical complexity and estimated energy savings potential. For the considered building, the greatest energy savings can be realised with exterior joinery renovation and installation of heat recovery ventilation. The implementation of booth measures accounts for about 50% of energy savings. With the comprehensive renovation, more than 80% of the annual heat required for the building would be preserved. In this case the specific heat transfer coefficient would decrease by about 60 %. On the contrary the requirements for cooling would increase, which is the common downside of a well-insulated building

Blocking of bacterial biofilm formation by a fish protein coating

Bacterial biofilm formation on inert surfaces is a significant health and economic problem in a wide range of environmental, industrial, and medical areas. Bacterial adhesion is generally a prerequisite for this colonization process and, thus, represents an attractive target for the development of biofilm-preventive measures. We have previously found that the preconditioning of several different inert materials with an aqueous fish muscle extract, composed primarily of fish muscle α-tropomyosin, significantly discourages bacterial attachment and adhesion to these surfaces. Here, this proteinaceous coating is characterized with regards to its biofilm-reducing properties by using a range of urinary tract infectious isolates with various pathogenic and adhesive properties. The antiadhesive coating significantly reduced or delayed biofilm formation by all these isolates under every condition examined. The biofilm-reducing activity did, however, vary depending on the substratum physicochemical characteristics and the environmental conditions studied. These data illustrate the importance of protein conditioning layers with respect to bacterial biofilm formation and suggest that antiadhesive proteins may offer an attractive measure for reducing or delaying biofilm-associated infections

The TibA Adhesin/Invasin from Enterotoxigenic Escherichia coli Is Self Recognizing and Induces Bacterial Aggregation and Biofilm Formation

Escherichia coli strains are responsible for many cases of gastrointestinal disease and represent a serious health problem worldwide. An essential step in the pathogenesis of such strains involves recognition and attachment to host intestinal surfaces. TibA is a potent bacterial adhesin associated with a number of enterotoxigenic E. coli strains and mediates bacterial attachment to a variety of human cells; additionally, it promotes invasion of such cells. This adhesin is a surface-displayed autotransporter protein and belongs to the exclusive group of bacterial glycoproteins; only the glycosylated form confers binding to and invasion of mammalian cells. Here we characterized TibA and showed that it possesses self-association characteristics and can mediate autoaggregation of E. coli cells. We demonstrated that intercellular TibA-TibA interaction is responsible for bacterial autoaggregation. Also, TibA expression significantly enhances biofilm formation by E. coli on abiotic surfaces

Glycosylation of the Self-Recognizing Escherichia coli Ag43 Autotransporter Protein

Glycosylation is a common modulation of protein function in eukaryotes and is biologically important. However, in bacteria protein glycosylation is rare, and relatively few bacterial glycoproteins are known. In Escherichia coli only two glycoproteins have been described to date. Here we introduce a novel member to this exclusive group, namely, antigen 43 (Ag43), a self-recognizing autotransporter protein. By mass spectrometry Ag43 was demonstrated to be glycosylated by addition of heptose residues at several positions in the passenger domain. Glycosylation of Ag43 by the action of the Aah and TibC glycosyltransferases was observed in laboratory strains. Importantly, Ag43 was also found to be glycosylated in a wild-type strain, suggesting that Ag43-glycosylation may be a widespread phenomenon. Glycosylation of Ag43 does not seem to interfere with its self-associating properties. However, the glycosylated form of Ag43 enhances bacterial binding to human cell lines, whereas the nonglycosylated version of Ag43 does not to confer this property