An RND-Type Efflux System in Borrelia burgdorferi Is Involved in Virulence and Resistance to Antimicrobial Compounds

Borrelia burgdorferi is remarkable for its ability to thrive in widely different environments due to its ability to infect various organisms. In comparison to enteric Gram-negative bacteria, these spirochetes have only a few transmembrane proteins some of which are thought to play a role in solute and nutrient uptake and excretion of toxic substances. Here, we have identified an outer membrane protein, BesC, which is part of a putative export system comprising the components BesA, BesB and BesC. We show that BesC, a TolC homolog, forms channels in planar lipid bilayers and is involved in antibiotic resistance. A besC knockout was unable to establish infection in mice, signifying the importance of this outer membrane channel in the mammalian host. The biophysical properties of BesC could be explained by a model based on the channel-tunnel structure. We have also generated a structural model of the efflux apparatus showing the putative spatial orientation of BesC with respect to the AcrAB homologs BesAB. We believe that our findings will be helpful in unraveling the pathogenic mechanisms of borreliae as well as in developing novel therapeutic agents aiming to block the function of this secretion apparatus

Evidence of Inbreeding Depression on Human Height

WOS:000306840400001Peer reviewe

Analysis of Vibration Measurements on Moving Trains

The development in society means that infrastructure like ballasted railway systems is facing challenges due to requests for a increased number of high-speed trains and heavier freight trains. This implies that ballasted railways get an increased impact from larger dynamic loads. The question is how the ballasted railways are today affected by dynamic loading and how will an increase in train speed and weight change the soil behavior within the railway embankment. A method of investigating soil behavior is via geophysical measurements. Accelerometers are commonly used for vibration measurements and by installing them on trains, measurements are possible to perform for complete railway sections. The knowledge of Eigen frequencies for various track components and soil layers are essential when considering frequency analysis of accelerometer measurements. Specifically, this means that the analysis is about detecting resonance of different components. From the actual case study, a good correlation is obtained between the expected Eigen frequencies and the measurement results. Thus, an assessment of the dynamic loadings influences on various soil layers and ballast has been possible to perform. Resonance of a soil layer means that the particles will be rearranged and degraded. For the case when saturated soil layers are subjected to resonance a phenomenon called liquefaction can occur if the pore pressures increases to the level were soil layers lose their effective stresses. Therefore, the most critical finding in this study is liquefaction because it leads to a loss in bearing capacity followed by settlements. Old railway tracks where little or no information exists of the soil conditions are the most suitable areas were this measurement and analysis method is of special use. Consequently, conventional borehole sampling can be reduced.ISBN för värdpublikation: 978-981-15-0449-5, 978-981-15-0450-1</p

Chromosomal aberrations and SCEs as biomarkers of cancer risk.

Previous studies have suggested that the frequency of chromosomal aberrations (CAs), but not of sister chromatid exchanges (SCEs), predicts cancer risk. We have further examined this relationship in European cohorts comprising altogether almost 22,000 subjects, in the framework of a European collaborative project (CancerRiskBiomarkers). The present paper gives an overview of some of the results of the project, especially as regards CAs and SCEs. The results confirm that a high level of CAs is associated with an increased risk of cancer and indicate that this association does not depend on the time between CA analysis and cancer detection, i.e., is obviously not explained by undetected cancer. The present evidence indicates that both chromatid-type and chromosome-type CAs predict cancer, even though some data suggest that chromosome-type CAs may have a more pronounced predictive value than chromatid-type CAs. CA frequency appears to predict cancers at various sites, although there seems to be a particular association with gastrointestinal cancers. SCE frequency does not appear to have cancer predictive value, at least partly due to uncontrollable technical variation. A number of genetic polymorphisms of xenobiotic metabolism, DNA repair, and folate metabolism affect the level of CAs and might collectively contribute to the cancer predictivity of CAs. Other factors that may influence the association between CAs and cancer include, e.g., exposure to genotoxic carcinogens and internal generation of genotoxic species. Although the association between CA level and cancer is seen at the group level, an association probably also exists for the individual, although it is not known if an individual approach could be feasible. However, group level evidence should be enough to support the use of CA analysis as a tool in screening programs and prevention policies in occupational and environmental health