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Now showing items 161-165 of 165
  • Mikonranta, Lauri; Mappes, Johanna; Laakso, Jouni; Ketola, Tarmo (BioMed Central, 2015)
    Abstract Background Pathogens evolve in a close antagonistic relationship with their hosts. The conventional theory proposes that evolution of virulence is highly dependent on the efficiency of direct host-to-host transmission. Many opportunistic pathogens, however, are not strictly dependent on the hosts due to their ability to reproduce in the free-living environment. Therefore it is likely that conflicting selection pressures for growth and survival outside versus within the host, rather than transmission potential, shape the evolution of virulence in opportunists. We tested the role of within-host selection in evolution of virulence by letting a pathogen Serratia marcescens db11 sequentially infect Drosophila melanogaster hosts and then compared the virulence to strains that evolved only in the outside-host environment. Results We found that the pathogen adapted to both Drosophila melanogaster host and novel outside-host environment, leading to rapid evolutionary changes in the bacterial life-history traits including motility, in vitro growth rate, biomass yield, and secretion of extracellular proteases. Most significantly, selection within the host led to decreased virulence without decreased bacterial load while the selection lines in the outside-host environment maintained the same level of virulence with ancestral bacteria. Conclusions This experimental evidence supports the idea that increased virulence is not an inevitable consequence of within-host adaptation even when the epidemiological restrictions are removed. Evolution of attenuated virulence could occur because of immune evasion within the host. Alternatively, rapid fluctuation between outside-host and within-host environments, which is typical for the life cycle of opportunistic bacterial pathogens, could lead to trade-offs that lower pathogen virulence.
  • Bashandy, Hany; Jalkanen, Salla; Teeri, Teemu H (BioMed Central, 2015)
    Abstract Background Transient gene expression utilizing syringe agroinfiltration offers a simple and efficient technique for different transgenic applications. Leaves of Nicotiana benthamiana show reliable and high transformation efficiency, but in quantitative assays also a certain degree of variation. We used a nested design in our agroinfiltration experiments to dissect the sources of this variation. Results An intron containing firefly luciferase gene was used as a reporter for agroinfiltration. A number of 6 week old tobacco plants were infiltrated for their top leaves, several samples were punched from the leaves after 2 days of transient expression, and protein extracts from the samples were repeatedly measured for luciferase activity. Interestingly, most of the variation was due to differences between the sampling spots in the leaves, the next important source being the different leaves on each plant. Variation between similar experiments, between plants and between repetitive measurements of the extracts could be easily minimized. Conclusions Efforts and expenditure of agroinfiltration experiments can be optimized when sources of variation are known. In summary, infiltrate more plants but less leaves, sample more positions on the leaf but run only few technical replicates.
  • Sartelli, Massimo; Viale, Pierluigi; Koike, Kaoru; Pea, Federico; Tumietto, Fabio; van Goor, Harry; Guercioni, Gianluca; Nespoli, Angelo; Tranà, Cristian; Catena, Fausto; Ansaloni, Luca; Leppaniemi, Ari; Biffl, Walter; Moore, Frederick A; Poggetti, Renato; Pinna, Antonio D; Moore, Ernest E (BioMed Central Ltd, 2011)
    Abstract Intra-abdominal infections are still associated with high rate of morbidity and mortality. A multidisciplinary approach to the management of patients with intra-abdominal infections may be an important factor in the quality of care. The presence of a team of health professionals from various disciplines, working in concert, may improve efficiency, outcome, and the cost of care. A World Society of Emergency Surgery (WSES) Consensus Conference was held in Bologna on July 2010, during the 1st congress of the WSES, involving surgeons, infectious disease specialists, pharmacologists, radiologists and intensivists with the goal of defining recommendations for the early management of intra-abdominal infections. This document represents the executive summary of the final guidelines approved by the consensus conference.
  • Remes, Hanna; Martikainen, Pekka (BioMed Central, 2015)
    Abstract Background Sociodemographic differences in injury mortality are well-established, but population-level studies on social patterns of injury morbidity remain few in numbers, particularly among young adults. Yet injuries are the leading cause of mortality, morbidity and disability among young people. Studies among children have shown steep social gradients in severe injuries, but less is known on the social patterning of injuries in late adolescence and early adulthood, when young people are in the process of becoming independent adults. This study examines how young adults’ current living arrangements, education, main economic activity, and parental social background are associated with hospital-treated injuries in late adolescence and early adulthood. Methods The study uses prospective, individual-level data gathered from several administrative sources. From a representative 11% sample of the total Finnish population, we included young people between ages 17–29 years during the follow-up (N = 134 938). We used incidence rates and Cox proportional hazards models to study hospital-treated injuries and poisonings in 1998–2008. Results Higher rates of injury were found among young adults living alone, single mothers, the lower educated and the non-employed, as well as those with lower parental social background, experience of childhood family changes or living with a single parent, and those who had left the parental home at a young age. Injury risks were consistently higher among young adults with lower education, but current living arrangements and main economic activity showed some age-related nuances in the associations: both earlier and later than average transitions in education, employment, and family formation associated with increased injury risks. The social differentials were strongest in poisonings, intentional self-harm, and assaults, but social patterns were also found in falls, traffic-related injuries and other unintentional injuries, underlining the existence of multiple distinct mechanisms and pathways behind the differentials. Conclusions The transition to adulthood is a life period of heightened risk of injury, during which both parental social background and the young people’s own social position are important determinants of serious injuries that require inpatient care.
  • Syrjänen, Leo; Valanne, Susanna; Kuuslahti, Marianne; Tuomela, Tea; Sriram, Ashwin; Sanz, Alberto; Jacobs, Howard T; Rämet, Mika; Parkkila, Seppo (BioMed Central, 2015)
    Abstract Background Carbonic anhydrases (CAs, EC are ubiquitous enzymes that catalyze the reversible hydration reaction of carbon dioxide. CAs are present as six structurally divergent enzyme families: α, β, γ, δ, ζ and η. β-CAs have a wide distribution across different species including invertebrates. Previously, we showed that Drosophila melanogaster β-CA is a highly active mitochondrial enzyme. In this study, we investigated the function of Drosophila β-CA by silencing the expression of the β-CA gene using UAS/GAL4-based RNA interference (RNAi) in Drosophila in vivo. Results Crossing β-CA RNAi lines over ubiquitous Actin driver flies did not produce any viable progeny, indicating that β-CA expression is required for fly development. RNAi silencing of β-CA ubiquitously in adult flies did not affect their survival rate or function of mitochondrial electron transport chain. Importantly, β-CA RNAi led to impaired reproduction. All β-CA knockdown females were sterile, and produced few or no eggs. Whole ovaries of knockdown females looked normal but upon cadherin staining, there was an apparent functional defect in migration of border cells, which are considered essential for normal fertilization. Conclusions These results indicate that although Drosophila β-CA is dispensable for survival of adult flies, it is essential for female fertility.