| 1. |
- Fan, Xuelong, et al.
(författare)
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Effects of sensor types and angular velocity computational methods in field measurements of occupational upper arm and trunk postures and movements
- 2021
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 21:16
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Tidskriftsartikel (refereegranskat)abstract
- Accelerometer-based inclinometers have dominated kinematic measurements in previous field studies, while the use of inertial measurement units that additionally include gyroscopes is rapidly increasing. Recent laboratory studies suggest that these two sensor types and the two commonly used angular velocity computational methods may produce substantially different results. The aim of this study was, therefore, to evaluate the effects of sensor types and angular velocity computational methods on the measures of work postures and movements in a real occupational setting. Half-workday recordings of arm and trunk postures, and movements from 38 warehouse workers were compared using two sensor types: accelerometers versus accelerometers with gyroscopes—and using two angular velocity computational methods, i.e., inclination velocity versus generalized velocity. The results showed an overall small difference (<2° and value independent) for posture percentiles between the two sensor types, but substantial differences in movement percentiles both between the sensor types and between the angular computational methods. For example, the group mean of the 50th percentiles were for accelerometers: 71°/s (generalized velocity) and 33°/s (inclination velocity)—and for accelerometers with gyroscopes: 31°/s (generalized velocity) and 16°/s (inclination velocity). The significant effects of sensor types and angular computational methods on angular velocity measures in field work are important in inter-study comparisons and in comparisons to recommended threshold limit values.
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| 2. |
- Forsman, Mikael, Professor, et al.
(författare)
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Mind the gap – development of conversion models between accelerometer- and IMU-based measurements of arm and trunk postures and movements in warehouse work
- 2022
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 105
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Tidskriftsartikel (refereegranskat)abstract
- Sensor type (accelerometers only versus inertial measurement units, IMUs) and angular velocity computational method (inclination versus generalized velocity) have been shown to affect the measurements of arm and trunk movements. This study developed models for conversions between accelerometer and IMU measurements of arm and trunk inclination and between accelerometer and IMU measurements of inclination and generalized (arm) velocities. Full-workday recordings from accelerometers and IMUs of arm and trunk postures and movements from 38 warehouse workers were used to develop 4 angular (posture) and 24 angular velocity (movement) conversion models for the distributions of the data. A power function with one coefficient and one exponent was used, and it correlated well (r2 > 0.999) in all cases to the average curves comparing one measurement with another. These conversion models facilitate the comparison and merging of measurements of arm and trunk movements collected using the two sensor types and the two computational methods.
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| 3. |
- Negrea, Aurel, et al.
(författare)
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Salicylidene Acylhydrazides That Affect Type III Protein Secretion in Salmonella enterica Serovar Typhimurium
- 2007
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Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804. ; 51:8, s. 2867-76
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Tidskriftsartikel (refereegranskat)abstract
- A collection of nine salicylidene acylhydrazide compounds were tested for their ability to inhibit the activity of virulence-associated type III secretion systems (T3SSs) in Salmonella enterica serovar Typhimurium. The compounds strongly affected Salmonella pathogenicity island 1 (SPI1) T3SS-mediated invasion of epithelial cells and in vitro secretion of SPI1 invasion-associated effector proteins. The use of a SPI1 effector ß-lactamase fusion protein implicated intracellular entrapment of the protein construct upon application of a salicylidene acylhydrazide, whereas the use of chromosomal transcriptional gene fusions revealed a compound-mediated transcriptional silencing of SPI1. Salicylidene acylhydrazides also affected intracellular bacterial replication in murine macrophage-like cells and blocked the transport of an epitope-tagged SPI2 effector protein. Two of the compounds significantly inhibited bacterial motility and expression of extracellular flagellin. We conclude that salicylidene acylhydrazides affect bacterial T3SS activity in S. enterica and hence could be used as lead substances when designing specific inhibitors of bacterial T3SSs in order to pharmaceutically intervene with bacterial virulence.
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| 4. |
- Ahmad, Irfan, et al.
(författare)
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BcsZ inhibits biofilm phenotypes and promotes virulence by blocking cellulose production in Salmonella enterica serovar Typhimurium
- 2016
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cellulose, a 1,4 beta-glucan polysaccharide, is produced by a variety of organisms including bacteria. Although the production of cellulose has a high biological, ecological and economical impact, regulatory mechanisms of cellulose biosynthesis are mostly unknown. Family eight cellulases are regularly associated with cellulose biosynthesis operons in bacteria; however, their function is poorly characterized. In this study, we analysed the role of the cellulase BcsZ encoded by the bcsABZC cellulose biosynthesis operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) in biofilm related behavior. We also investigated the involvement of BcsZ in pathogenesis of S. Typhimurium including a murine typhoid fever infection model. Result: In S. Typhimurium, cellulase BcsZ with a putative periplasmic location negatively regulates cellulose biosynthesis. Moreover, as assessed with a non-polar mutant, BcsZ affects cellulose-associated phenotypes such as the rdar biofilm morphotype, cell clumping, biofilm formation, pellicle formation and flagella-dependent motility. Strikingly, although upregulation of cellulose biosynthesis was not observed on agar plate medium at 37 degrees C, BcsZ is required for efficient pathogen-host interaction. Key virulence phenotypes of S. Typhimurium such as invasion of epithelial cells and proliferation in macrophages were positively regulated by BcsZ. Further on, a bcsZ mutant was outcompeted by the wild type in organ colonization in the murine typhoid fever infection model. Selected phenotypes were relieved upon deletion of the cellulose synthase BcsA and/or the central biofilm activator CsgD. Conclusion: Although the protein scaffold has an additional physiological role, our findings indicate that the catalytic activity of BcsZ effectively downregulates CsgD activated cellulose biosynthesis. Repression of cellulose production by BcsZ subsequently enables Salmonella to efficiently colonize the host.
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| 5. |
- Avican, Kemal, et al.
(författare)
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RNA atlas of human bacterial pathogens uncovers stress dynamics linked to infection
- 2021
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial processes necessary for adaption to stressful host environments are potential targets for new antimicrobials. Here, we report large-scale transcriptomic analyses of 32 human bacterial pathogens grown under 11 stress conditions mimicking human host environments. The potential relevance of the in vitro stress conditions and responses is supported by comparisons with available in vivo transcriptomes of clinically important pathogens. Calculation of a probability score enables comparative cross-microbial analyses of the stress responses, revealing common and unique regulatory responses to different stresses, as well as overlapping processes participating in different stress responses. We identify conserved and species-specific ‘universal stress responders’, that is, genes showing altered expression in multiple stress conditions. Non-coding RNAs are involved in a substantial proportion of the responses. The data are collected in a freely available, interactive online resource (PATHOgenex).
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| 6. |
- Behra, Phani Rama Krishna
(författare)
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Comparative genomics of the genus Mycobacterium : Genome evolution, phylogeny and diversity
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The genus Mycobacterium includes more than 190 species, and many cause severe diseases such as tuberculosis and leprosy. According to the "World Health Organization", in year 2019 alone, 10 million people developed TB, and 1.4 million died. TB had been in decline in developed countries, but made its reappearance as an opportunistic pathogen targeting immuno-compromised AIDS victims. Also, non-tuberculosis mycobacteria (NTM) infections have emerged as a major infectious agent in recent times. NTM occupy diverse ecological niches and can be isolated from soil, tap water, and groundwater. This thesis has investigated the Mycobacterium species from a genomic perspective, focusing on the biology of virulence factors, mobile genetic elements, tRNAs, and non-coding RNAs and their evolutionary distribution and possible relationship with phenotypic diversity. As part of this study, we have sequenced 153 mycobacterial genomes, including type strains, environmental samples, isolates from hospital patients, infected fish, and outbreak samples in an animal facility at Uppsala University. We have provided a phylogenetic tree based on 387 (and 56) core genes covering most species (244 genomes) constituting the Mycobacterium genus. The core gene phylogeny resulted in 33 clades. Subsequently, we have covered different clade groups, such as, M. marinum, M. mucogenicum, M. chelonae and M. chlorophenolicum and investigated the NTM clade-specific genome diversity and evolution. Our examination of non-coding genes showed that the total number of tRNA genes per species varies between 42 and 90. Among the species with more than 50 tRNAs, additional tRNA genes are likely acquired through horizontal gene transfer (HGT), as supported by the presence of closely linked HNH endonuclease gene and GOLLD RNA. We have explored the presence of selenocysteine utility and the gene for selenoprotein "formate dehydrogenase" among 244 mycobacterial genomes. For the M. chlorophenolicum clade, we have explored genes with a role in the bioremediation process. Comparative genomics of M. marinum and M. chelonae clade groups suggest new clusters or subspecies. Mutational hotspots are relatively higher in M. marinum compared to that in M. tuberculosis and M. salmoniphilum. Relatively higher number of hotspots in M. marinum is likely related to its ability to occupy different ecological niches. Finally, the thesis uncovered IS elements, phage sequences, plasmids, tRNA, and ncRNA contributing to mycobacterial evolution.
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| 7. |
- Boekel, Jorrit, et al.
(författare)
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Comparative tissue transcriptomics reveal prompt inter-organ communication in response to local bacterial kidney infection
- 2011
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 12, s. 123-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mucosal infections elicit inflammatory responses via regulated signaling pathways. Infection outcome depends strongly on early events occurring immediately when bacteria start interacting with cells in the mucosal membrane. Hitherto reported transcription profiles on host-pathogen interactions are strongly biased towards in vitro studies. To detail the local in vivo genetic response to infection, we here profiled host gene expression in a recent experimental model that assures high spatial and temporal control of uropathogenic Escherichia coli (UPEC) infection within the kidney of a live rat. Results: Transcriptional profiling of tissue biopsies from UPEC-infected kidney tissue revealed 59 differentially expressed genes 8 h post-infection. Their relevance for the infection process was supported by a Gene Ontology (GO) analysis. Early differential expression at 3 h and 5 h post-infection was of low statistical significance, which correlated to the low degree of infection. Comparative transcriptomics analysis of the 8 h data set and online available studies of early local infection and inflammation defined a core of 80 genes constituting a "General tissue response to early local bacterial infections". Among these, 25% were annotated as interferon-gamma (IFN-gamma) regulated. Subsequent experimental analyses confirmed a systemic increase of IFN-gamma in rats with an ongoing local kidney infection, correlating to splenic, rather than renal Ifng induction and suggested this inter-organ communication to be mediated by interleukin (IL)-23. The use of comparative transcriptomics allowed expansion of the statistical data handling, whereby relevant data could also be extracted from the 5 h data set. Out of the 31 differentially expressed core genes, some represented specific 5 h responses, illustrating the value of comparative transcriptomics when studying the dynamic nature of gene regulation in response to infections. Conclusion: Our hypothesis-free approach identified components of infection-associated multi-cellular tissue responses and demonstrated how a comparative analysis allows retrieval of relevant information from lower-quality data sets. The data further define marked representation of IFN-gamma responsive genes and a prompt inter-organ communication as a hallmark of an early local tissue response to infection.
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| 8. |
- Butina, Karen, et al.
(författare)
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Electrochemical sensing of bacteria via secreted redox active compounds using conducting polymers
- 2019
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 297
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial infections and antibiotic resistance represent major global threats to public health. Current diagnostics use culture based assays that are reliable but slow, hence appealing for new rapid methods. Here we describe redox sensing as a novel concept for rapid, label-free detection of bacteria. We utilize a two-electrode poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) based sensor for detection of bacterially secreted redox-active compounds. Using purified redox-active compounds, we show the ability of the sensor to detect and quantify compounds in micromolar concentrations within minutes. When applied for detection and quantification of Salmonella, we show that secreted, low molecular weight redox compounds cause reduction of the PEDOT:PSS electrode. A potential role of redox sensing in infection diagnostics was demonstrated as uropathogenic strains of E. coli., Staphylococcus, Enterococcus, Pseudomonas, Proteus, and Klebsiella spp., major causes of complicated urinary tract infections, were successfully detected in complex media or processed urine. Since numerous bacterial species are capable of extracellular electron transfer, redox sensing may find use as a generic method for bacterial detection with applications in research laboatories, the clinic and industry alike.
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| 9. |
- Del Bel Belluz, Lisa, et al.
(författare)
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The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection
- 2016
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Ingår i: PLoS Pathogens. - : Public Library Science. - 1553-7366 .- 1553-7374. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address this issue, we assessed the effects of the Salmonella enterica genotoxin, known as typhoid toxin, in in vivo models of murine infection. Immunocompetent mice were infected with isogenic S. enterica, serovar Typhimurium (S. Typhimurium) strains, encoding either a functional or an inactive typhoid toxin. The presence of the genotoxic subunit was detected 10 days post-infection in the liver of infected mice. Unexpectedly, its expression promoted the survival of the host, and was associated with a significant reduction of severe enteritis in the early phases of infection. Immunohistochemical and transcriptomic analysis confirmed the toxin-mediated suppression of the intestinal inflammatory response. The presence of a functional typhoid toxin further induced an increased frequency of asymptomatic carriers. Our data indicate that the typhoid toxin DNA damaging activity increases host survival and favours long-term colonization, highlighting a complex cross-talk between infection, DNA damage response and host immune response. These findings may contribute to understand why such effectors have been evolutionary conserved and horizontally transferred among Gram-negative bacteria.
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| 10. |
- Eckert, Johannes A., et al.
(författare)
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An optotracer-based antibiotic susceptibility test specifically targeting the biofilm lifestyle of Salmonella
- 2022
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Ingår i: Biofilm. - : Elsevier BV. - 2590-2075. ; 4, s. 100083-
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial resistance is a medical threat of global dimensions. Proper antimicrobial susceptibility testing (AST) for drug development, patient diagnosis and treatment is crucial to counteract ineffective drug use and resistance development. Despite the important role of bacterial biofilms in chronic and device-associated in-fections, the efficacy of antibiotics is determined using planktonic cultures. To address the need for antibiotics targeting bacteria in the biofilm lifestyle, we here present an optotracing-based biofilm-AST using Salmonella as model. Our non-disruptive method enables real-time recording of the extracellular matrix (ECM) components, providing specific detection of the biofilm lifestyle. Biofilm formation prior to antibiotic challenge can thus be confirmed and pre-treatment data collected. By introducing Kirby-Bauer discs, we performed a broad screen of the effects of antibiotics representing multiple classes, and identified compounds with ECM inhibitory as well as promoting effects. These compounds were further tested in agar-based dose-response biofilm-AST assays. By quantifying the ECM based on the amount of curli, and by visualizing the biofilm size and morphology, we achieved new information directly reflecting the treated biofilm. This verified the efficacy of several antibiotics that were effective in eradicating pre-formed biofilms, and it uncovered intriguing possible resistance mecha-nisms initiated in response to treatments. By providing deeper insights into the resistances and susceptibilities of microbes, expanded use of the biofilm-AST will contribute to more effective treatments of infections and reduced resistance development.
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| 11. |
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| 12. |
- Fan, Xuelong, et al.
(författare)
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Ergonomic Evaluation of a Prototype Console for Robotic Surgeries via Simulations with Digital Human Manikins
- 2019
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Ingår i: Proceedings of the 20th Congress of the International Ergonomics Association (IEA 2018) Volume V: Human Simulation and Virtual Environments, Work With Computing Systems (WWCS), Process Control. - Cham : Springer International Publishing. - 2194-5365 .- 2194-5357. - 9783319960760 ; 822, s. 351-363
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Konferensbidrag (refereegranskat)abstract
- Work-related musculoskeletal disorders impact surgical performance, which increase risks for patient safety. A new console has been designed to reduce workload for robotic surgery surgeons. Due to high costs and long waiting time of the production process, a pre-production ergonomic evaluation of the new design is preferable. In this paper, we evaluate if the new console at the pre-production stage by using an US checklist, and the Swedish standard for visual display unit work. A 3D model of the new designed console was introduced to the virtual environment of a digital manikin (Intelligently Moving Manikin, IMMA). The work-ranges of the console were calculated. Various individual work distances of 12 manikins (3 men and 3 women per each of the US and the Swedish population) were “measured”. The data were integrated and used as an objective reference to compare with the Swedish standard, and the US checklist. The result shows that the criteria in the Swedish standard and the US checklist are fulfilled, except for those are related to the adjustable range of the screen view height, the height range of the armrest and the adjustable distance of the pedals. The new console fulfills most of the criteria in the checklist and the standard, but there is room for a few improvements. The DHM tool IMMA provides the possibility for a pre-production assessment. However, the limited virtual measurement tools of IMMA restrained the time efficiency of the ergonomic assessment.
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| 13. |
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| 14. |
- Forsman, Mikael, et al.
(författare)
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Inter-ergonomist Reliability in Rating Risk Level - without any Specific Method - in Ten Video Recorded Work Tasks
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 1. IntroductionRecently, 30 observational methods for assessment of biomechanical exposures at work were evaluated through a literature review (Takala et al., 2010). It was found that several methods are insufficiently tested in terms of validity and reliability. In only in a few cases have estimates of the components of the methods been validated against technical measurements. Also comparisons between methods' resulting risk levels are rare. Swedish Work Environment Authority has recently increased the demands on ergonomic risk assessments. These assessments are usually made by ergonomists in occupational health services (OHS).This study is included in a larger on-going project, with the overall purpose to evaluate six observational methods for assessment of biomechanical exposures of repetitive work in respect of validity, reliability and usability, as well as provide information on which of the methods are best suited for practitioners in risk assessment of repetitive work. The methods' resulting risk levels are compared not only to each other, but also to ergonomists’ “own” risk estimates (i.e., done without any specific method). The specific aim of this sub-study was to investigate the inter-observer reliability of ergonomists’ own risk estimates.2. MethodsNine OHS-ergonomists, all with more than 5 years of experience of general ergonomic risk assessments, made risk assessments of 10 different video-recorded (2-6 minutes) work-tasks (supermarket work, meat cutting and packing, engine assembly, cleaning, post sorting and hairdressing). Video sequences of two or three camera angles were synchronized and showed together. For each work-task, the ergonomists were given data of the work task length (see Table 1), pause- and rests schedules, weights of handled goods, physical factors, and the employees own ratings of discomfort, work demands and own control.The ergonomist could pause the playback as needed, the maximum allocated time per work-task assessment was 20 minutes. The risk of musculoskeletal disorders and need for improvements was rated into green (no risk), yellow (investigate further), and red (immediate risk) categories. Ratings were done for 8 specific body regions: neck, lower back, right and left shoulders, -arms/elbows, and -wrists/hands), and for one over-all risk level.The agreement of the ratings (in percent), and Light’s multi-observer kappa (i.e. Cohen’s pairwise kappa averaged over all pairs; Light, 1971; Cohen, 1960) were calculated per body region and for the over-all risk assessment.3. ResultsFor the 720 (9 ergonomists, 8 body regions, 10 work tasks) risk assessments of the separate body regions, 37% were green, 44% yellow and 19% red. For over-all risk assessments (Table 1), 14% were green, 50% yellow and 36% red.Table 1. Work tasks, hours per work task per work day, and the ergonomists ratings of over risk As seen in Table 1, the consistency between the observers differed markedly. For three of the work tasks all three categories were represented, only in one task all ergonomists rated the over-all risk equally. The average agreement of the ratings were 48% regarding the body regions, and 57% regarding the over-all risk assessments, Light’s kappa was 0.18 and 0.30, respectively.4. DiscussionThe results showed fair inter-observer reliability according to Altman’s table for interpretation of kappa (kappa between 0.21 and 0.40; Altman, 1991). These kappa values will, in the major project, be compared to those of six systematic observation methods.5. ReferencesAltman DG (1991) Practical statistics for medical research. London: Chapman and Hall.Cohen J. A coefficient of agreement for nominal scales. Educational and Psychological Measurement. 1960;20(1):37–46.Light RJ. Measures of response agreement for qualitative data: Some generalizations and alternatives. Psychological Bulletin. 1971;76(5):365–377.Takala EP et al. 2010. Systematic evaluation of observational methods assessing biomechanical exposures at work. Scand J Work E
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| 15. |
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| 16. |
- Forsman, Mikael, et al.
(författare)
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Reliability in twelve ergonomists’ three-category risk ratings in ten video recorded work tasks.
- 2015
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Ingår i: Proceedings 19<sup>th</sup> Triennial Congress of the IEA, Melbourne 9-14 August 2015.
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Konferensbidrag (refereegranskat)abstract
- The Swedish Work Environment Authority has recently increased the demands on ergonomic risk assessments. These assessments are usually made by ergonomists in occupational health services (OHS). Although they are many observational methods that may be used (Takala, Pehkonen et al. 2010), the ergonomists often do risk assessment by sole observation, based on his/her own knowledge and experience, without the use of any specific method.This study is included in a larger on-going OBS project, with the overall purpose to evaluate six observational methods for assessment of biomechanical exposures of repetitive work in respect of validity, reliability and usability, as well as provide information on which of the methods are best suited for practitioners in risk assessment of repetitive work. The methods' resulting risk levels will be compared not only to each other, but also to the ergonomists’ “own” assessments (without any specific method) of the risk of developing musculoskeletal disorders.The specific aim of this sub-study was to investigate the inter-observer reliability of ergonomists’ own risk assessments without any specific method
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| 17. |
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| 18. |
- Gomez-Carretero, Salvador, et al.
(författare)
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Salmonella Biofilm Modulation with Electrically Conducting Polymers
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Biofilms are ubiquitous in many human activities, constituting a threat or an advantage depending on the context of application. It is therefore of great interest to obtain new materials to study and control how biofilms are formed. Here, heparin and DBS (dodecylbenzenesulfonate) are incorporated as counter-ions to the PEDOT (poly(3,4-ethylenedioxythiophene)) backbone, forming conducting polymer thin-films. Polymer synthesis is based on electrodeposition, allowing for the adjustment, during fabrication, of properties like charge and hydrophobicity, important in bacterial adhesion. The electrochemical redox state of the polymer is of fundamental importance in Salmonella enterica Serovar Typhimurium biofilm modulation. Oxidized composites show increased levels of biofilm growth compared to reduced and pristine polymer films. As a result, biofilm formation is modulated by the application of a low electric voltage. Moreover, biofilm morphology and topology are affected by both the electrochemical redox state and the incorporated counter-ion, making these materials a useful tool in biofilm engineering.
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| 19. |
- Guidi, Riccardo, et al.
(författare)
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Salmonella enterica delivers its genotoxin through outer membrane vesicles secreted from infected cells
- 2013
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Ingår i: Cellular Microbiology. - : Wiley-Blackwell. - 1462-5814 .- 1462-5822. ; 15:12, s. 2034-2050
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Tidskriftsartikel (refereegranskat)abstract
- Cytolethal-distending toxins (CDTs) belong to a family of DNA damage inducing exotoxins that are produced by several Gram-negative bacteria. Salmonella enterica serovar Typhi expresses its CDT (named as Typhoid toxin) only in the Salmonella-containing vacuole (SCV) of infected cells, which requires its export for cell intoxication. The mechanisms of secretion, release in the extracellular space and uptake by bystander cells are poorly understood. We have addressed these issues using a recombinant S. Typhimurium strain, MC71-CDT, where the genes encoding for the PltA, PltB and CdtB subunits of the Typhoid toxin are expressed under control of the endogenous promoters. MC71-CDT grown under conditions that mimic the SCV secreted the holotoxin in outer membrane vesicles (OMVs). Epithelial cells infected with MC71-CDT also secreted OMVs-like vesicles. The release of these extracellular vesicles required an intact SCV and relied on anterograde transport towards the cellular cortex on microtubule and actin tracks. Paracrine internalization of Typhoid toxin-loaded OMVs by bystander cells was dependent on dynamin-1, indicating active endocytosis. The subsequent induction of DNA damage required retrograde transport of the toxin through the Golgi complex. These data provide new insights on the mode of secretion of exotoxins by cells infected with intracellular bacteria.
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| 20. |
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| 21. |
- Herwald, Heiko, et al.
(författare)
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Activation of the contact-phase system on bacterial surfaces - A clue to serious comlications in infections deseases
- 1998
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 4:3, s. 298-302
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Tidskriftsartikel (refereegranskat)abstract
- Fever, hypotension and bleeding disorders are common symptoms of sepsis and septic shock. The activation of the contact-phase system is thought to contribute to the development of these severe disease states by triggering proinflammatory and procoagulatory cascades; however, the underlying molecular mechanisms are obscure. Here we report that the components of the contact-phase system are assembled on the surface of Escherichia coil and Salmonella through their specific interactions with fibrous bacterial surface proteins, curli and fimbriae. As a consequence, the proinflammatory pathway is activated through the release of bradykinin, a potent inducer of fever, pain and hypotension. Absorption of contact-phase proteins and fibrinogen by bacterial surface proteins depletes relevant coagulation factors and causes a hypocoagulatory state. Thus, the complex interplay of microbe surface proteins and host contact-phase factors may contribute to the symptoms of sepsis and septic shock.
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| 22. |
- Holm, Angelika
(författare)
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Aquaporins in Infection and Inflammation
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ability of eukaryotic cells to change their shape and to migrate directionally is highly dependent on active volume regulation in cells building up tissues as well as in individual cells. Transmembrane fluxes of water via specialized water channels, called aquaporins (AQPs), facilitate the changes of volume and shape, which additionally require a complex interplay between the plasma membrane and the cytoskeleton. AQPs have been shown to be involved in the development of inflammatory processes and diseases. The aims of the studies underlying this thesis were to further elucidate the expression and function of AQPs in both bacterial and viral infections as well as in the inflammatory disease, microscopic colitis. For this, molecular techniques qPCR, immunoblotting and live, holographic, confocal and super-resolution imaging were used.When cells of the innate immune system encounter pathogens they need to respond and prepare for migration and phagocytosis and do so through volume regulatory processes. The Gramnegative bacterium Pseudomonas aeruginosa utilizes a small molecule-based communication system, called quorum sensing (QS) to control the production of its virulence factors and biofilms. We found that P. aeruginosa with a complete QS system elicits a stronger phagocytic response in human blood-derived macrophages compared to its lasI-/rhlI- mutant lacking the production of the QS molecules N-butyryl-L-homoserine lactone (C4-HSL) and N-3-oxododecanoyl-L-homoserine lactone (3O-C12-HSL). Infection with P. aeruginosa further increases the expression of AQP9 and induces re-localisation of AQP9 to the front and trailing ends of macrophages. Moreover, the 3O-C12-HSL alone elevates the expression of AQP9, redistribute the water channel to the front and rear ends and increases the cell area and volume of macrophages. Both infection with the wild type P. aeruginosa and the treatment with 3OC12-HSL change the nano-structural architecture of the AQP9 distribution in macrophages.Viruses use the intracellular machinery of the invaded cells to produce and assemble new viral bodies. Intracellular AQPs are localised in a membranes of cellular organelles to regulate their function and morphology. C3H10T1/2 fibroblasts transiently expressing green fluorescent protein (GFP)-AQP6 show a reduced expression of AQP6 after Hazara virus infection and an increased cell area. Overexpressing AQP6 in C3H10T1/2 cells reduces the infectivity of Hazara virus indicating that AQP6 expression has a protective role in virus infections.Ion and water channels in the epithelial cell lining tightly regulate the water homeostasis. In microscopic colitis (MC), patients suffer from severe watery diarrhoeas. For the first time, we have shown that the expression of AQP1, 8 and 11 and the sodium/hydrogen exchanger NHE1 are reduced in colonic biopsies from MC patients compared to healthy control individuals. Following treatment with the glucocorticoid budesonide the patients experienced a rapid recovery and we observed a restored or increased expression of the AQPs and NHE1 during treatment, suggesting a role for AQPs in the diarrhoeal mechanisms in MC.Taken together, this thesis provides new evidence on the importance of water homeostasis regulation through AQPs during infections and inflammation and opens up a door for further investigations of roles for AQPs in inflammatory processes.
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| 23. |
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| 24. |
- Kjellberg, Katarina, et al.
(författare)
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Comparisons of six observational methods for risk assessment of repetitive work - results from a consensus assessment
- 2015
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Ingår i: Proceedings 19<sup>th</sup> Triennial Congress of the IEA, Melbourne 9-14 August 2015.
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Konferensbidrag (refereegranskat)abstract
- During last decades several risk assessment methods for physical ergonomics have been developed. In a literature review 30 observational methods for assessment of biomechanical exposures at work were evaluated (1). It was found that several methods are insufficiently tested in terms of validity and reliability. Comparisons between methods' resulting risk levels are rare. The Swedish Work Environment Authority has recently emphasized the demands on risk assessments of musculoskeletal disorders (2). Practitioners mostly use observational methods to assess biomechanical risks(1). Despite a recent study comparing eight methods evaluating risk factors associated with musculoskeletal disorders (3), there is a lack of knowledge and guidance on which methods are the most effective and valid.This study is part of a larger on-going project, the OBS-project, with the overall purpose to evaluate six observational methods for assessment of biomechanical exposures of repetitive work in respect of validity, reliability and usability. A further purpose is to provide information on which of the methods are best suited for practitioners in risk assessment of repetitive work. The specific aim of this sub-study was to investigate the agreement between six observational methods for risk assessment of repetitive work by comparing the risk levels as assessed by a group of experts.
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| 25. |
- Koskiniemi, Sanna, et al.
(författare)
-
Pathoadaptive Mutations in Salmonella enterica Isolated after Serial Passage in Mice
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:7, s. e70147-
-
Tidskriftsartikel (refereegranskat)abstract
- How pathogenic bacteria adapt and evolve in the complex and variable environment of the host remains a largely unresolved question. Here we have used whole genome sequencing of Salmonella enterica serovar Typhimurium LT2 populations serially passaged in mice to identify mutations that adapt bacteria to systemic growth in mice. We found unique pathoadaptive mutations in two global regulators, phoQ and stpA, which increase the competitive indexes of the bacteria 3- to 5-fold. Also, all mouse-adapted lineages had changed the orientation of the hin invertable element, resulting in production of a FliC type of flagellum. Competition experiments in mice with locked flagellum mutants showed that strains expressing the FliC type of flagellum had a 5-fold increase in competitive index as compared to those expressing FljB type flagellum. Combination of the flagellum cassette inversion with the stpA mutation increased competitive indexes up to 20-fold. These experiments show that Salmonella can rapidly adapt to a mouse environment by acquiring a few mutations of moderate individual effect that when combined confer substantial increases in growth.
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| 26. |
- Lofton, Hava, et al.
(författare)
-
Fitness of Salmonella mutants resistant to antimicrobial peptides
- 2015
-
Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 70:2, s. 432-440
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To examine the effects of mutations in the waaY, phoP and pmrB genes, which confer resistance to antimicrobial peptides (AMPs), on fitness of Salmonella Typhimurium. Methods: Survival during low pH, oxidative stress, stationary-phase incubation, exposure to serum and bile and growth in mice and laboratory media were determined by time-kills, disc inhibition assays, competition experiments and optical density measurements. Results: Individual mutations in the waaY gene (involved in LPS core biosynthesis) and in the phoP and pmrB genes (part of two different two-component regulatory systems, phoPQ and pmrAB) conferred no or minor effects on bacterial survival during stressful in vitro conditions or in mice. In contrast, a waaY-phoP-pmrB triple mutant was compromised under most assay conditions. Conclusions: Results from this study show that AMP resistance can be cost-free, as assessed by several assays that attempt to mimic the conditions a bacterium might encounter within a host. Our findings imply that future therapeutic use of AMPs could select for fit mutants with cross-resistance to human defence peptides and that potential resistance development in response to therapeutic use of AMPs needs to be carefully monitored.
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| 27. |
- Macvanin, Mirjana, et al.
(författare)
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Fusidic acid-resistant mutants of Salmonella enterica serovar Typhimurium with low fitness in vivo are defective in RpoS induction
- 2003
-
Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 47:12, s. 3743-3749
-
Tidskriftsartikel (refereegranskat)abstract
- Mutants of Salmonella enterica serovar Typhimurium resistant to fusidic acid (Fusr) have mutations in fusA, the gene encoding translation elongation factor G (EF-G). Most Fusr mutants have reduced fitness in vitro and in vivo, in part explained by mutant EF-G slowing the rate of protein synthesis and growth. However, some Fusr mutants with normal rates of protein synthesis still suffer from reduced fitness in vivo. As shown here, Fusr mutants could be similarly ranked in their relative fitness in mouse infection models, in a macrophage infection model, in their relative hypersensitivity to hydrogen peroxide in vivo and in vitro, and in the amount of RpoS production induced upon entry into the stationary phase. We identify a reduced ability to induce production of RpoS (sigmas) as a defect associated with Fusr strains. Because RpoS is a regulator of the general stress response, and an important virulence factor in Salmonella, an inability to produce RpoS in appropriate amounts can explain the low fitness of Fusr strains in vivo. The unfit Fusr mutants also produce reduced levels of the regulatory molecule ppGpp in response to starvation. Because ppGpp is a positive regulator of RpoS production, we suggest that a possible cause of the reduced levels of RpoS is the reduction in ppGpp production associated with mutant EF-G. The low fitness of Fusr mutants in vivo suggests that drugs that can alter the levels of global regulators of gene expression deserve attention as potential antimicrobial agents.
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| 28. |
- Martin, Océane C.B., et al.
(författare)
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Influence of the microenvironment on modulation of the host response by typhoid toxin
- 2021
-
Ingår i: Cell Reports. - : Cell Press. - 2211-1247. ; 35:1
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial genotoxins cause DNA damage in eukaryotic cells, resulting in activation of the DNA damage response (DDR) in vitro. These toxins are produced by Gram-negative bacteria, enriched in the microbiota of inflammatory bowel disease (IBD) and colorectal cancer (CRC) patients. However, their role in infection remains poorly characterized. We address the role of typhoid toxin in modulation of the host-microbial interaction in health and disease. Infection with a genotoxigenic Salmonella protects mice from intestinal inflammation. We show that the presence of an active genotoxin promotes DNA fragmentation and senescence in vivo, which is uncoupled from an inflammatory response and unexpectedly associated with induction of an anti-inflammatory environment. The anti-inflammatory response is lost when infection occurs in mice with acute colitis. These data highlight a complex context-dependent crosstalk between bacterial-genotoxin-induced DDR and the host immune response, underlining an unexpected role for bacterial genotoxins.
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| 29. |
- Martin-Rodriguez, Alberto J., et al.
(författare)
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Nitrate Metabolism Modulates Biosynthesis of Biofilm Components in Uropathogenic Escherichia coli and Acts as a Fitness Factor During Experimental Urinary Tract Infection
- 2020
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- To successfully colonize a variety of environments, bacteria can coordinate complex collective behaviors such as biofilm formation. To thrive in oxygen limited niches, bacteria's versatile physiology enables the utilization of alternative electron acceptors. Nitrate, the second most favorable electron acceptor after oxygen, plays a prominent role in the physiology of uropathogenic Escherichia coli (UPEC) and is abundantly found in urine. Here we analyzed the role of extracellular nitrate in the pathogenesis of the UPEC strain CFT073 with an initial focus on biofilm formation. Colony morphotyping in combination with extensive mutational, transcriptional, and protein expression analyses of CFT073 wild-type and mutants deficient in one or several nitrate reductases revealed an association between nitrate reduction and the biosynthesis of biofilm extracellular matrix components. We identified a role for the nitrate response regulator NarL in modulating expression of the biofilm master regulator CsgD. To analyze the role of nitrate reduction during infection in vivo, we tested wild-type CFT073 and a nitrate reductase null mutant in an ascending urinary tract infection (UTI) model. Individually, each strain colonized extensively, suggesting that nitrate reduction is expendable during UTI. However, during competitive co-infection, the strain incapable of nitrate reduction was strongly outcompeted. This suggests that nitrate reduction can be considered a non-essential but advantageous fitness factor for UPEC pathogenesis. This implies that UPEC rapidly adapts their metabolic needs to the microenvironment of infected tissue. Collectively, this work demonstrates a unique association between nitrate respiration, biofilm formation, and UPEC pathogenicity, highlighting how the use of alternative electron acceptors enables bacterial pathogens to adapt to challenging infectious microenvironments.
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| 30. |
- Nyman, Teresia, et al.
(författare)
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Reliability and Validity of Six Selected Observational Methods for Risk Assessment of Hand Intensive and Repetitive Work
- 2023
-
Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 20:8, s. 5505-
-
Tidskriftsartikel (refereegranskat)abstract
- Risk assessments of hand-intensive and repetitive work are commonly done using observational methods, and it is important that the methods are reliable and valid. However, comparisons of the reliability and validity of methods are hampered by differences in studies, e.g., regarding the background and competence of the observers, the complexity of the observed work tasks and the statistical methodology. The purpose of the present study was to evaluate six risk assessment methods, concerning inter- and intra-observer reliability and concurrent validity, using the same methodological design and statistical parameters in the analyses. Twelve experienced ergonomists were recruited to perform risk assessments of ten video-recorded work tasks twice, and consensus assessments for the concurrent validity were carried out by three experts. All methods’ total-risk linearly weighted kappa values for inter-observer reliability (when all tasks were set to the same duration) were lower than 0.5 (0.15–0.45). Moreover, the concurrent validity values were in the same range with regards to total-risk linearly weighted kappa (0.31–0.54). Although these levels are often considered as being fair to substantial, they denote agreements lower than 50% when the expected agreement by chance has been compensated for. Hence, the risk of misclassification is substantial. The intra-observer reliability was only somewhat higher (0.16–0.58). Regarding the methods ART (Assessment of repetitive tasks of the upper limbs) and HARM (Hand Arm Risk Assessment Method), it is worth noting that the work task duration has a high impact in the risk level calculation, which needs to be taken into account in studies of reliability. This study indicates that when experienced ergonomists use systematic methods, the reliability is low. As seen in other studies, especially assessments of hand/wrist postures were difficult to rate. In light of these results, complementing observational risk assessments with technical methods should be considered, especially when evaluating the effects of ergonomic interventions.
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| 31. |
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| 32. |
- Pränting, Maria, et al.
(författare)
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Mechanism and fitness costs of PR-39 resistance in Salmonella enterica serovar Typhimurium LT2
- 2008
-
Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 52:8, s. 2734-2741
-
Tidskriftsartikel (refereegranskat)abstract
- PR-39 is a porcine antimicrobial peptide that kills bacteria with a mechanism that does not involve cell lysis. Here, we demonstrate that Salmonella enterica serovar Typhimurium can rapidly acquire mutations that reduce susceptibility to PR-39. Resistant mutants appeared at a rate of 0.4 x 10(-6) per cell per generation. These mutants were about four times more resistant than the wild type and showed a greatly reduced rate of killing. Genetic analysis revealed mutations in the putative transport protein SbmA as being responsible for the observed resistance. These sbmA mutants were as fit as the wild-type parental strain as measured by growth rates in culture medium and mice and by long-term survival in stationary phase. These results suggest that resistance to certain antimicrobial peptides can rapidly develop without an obvious fitness cost for the bacteria and that resistance development could become a threat to the efficacy of antimicrobial peptides if used in a clinical setting.
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| 33. |
- Puiac, Speranta, et al.
(författare)
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Small-molecular virulence inhibitors show divergent and immunomodulatory effects in infection models of Salmonella enterica serovar Typhimurium
- 2011
-
Ingår i: International Journal of Antimicrobial Agents. - : Elsevier BV. - 0924-8579 .- 1872-7913. ; 38:5, s. 409-416
-
Tidskriftsartikel (refereegranskat)abstract
- The virulence-associated Salmonella pathogenicity island 2 (SPI2) type III secretion system supports intracellular replication of Salmonella enterica serovar Typhimurium in macrophage-like RAW264.7 cells. In contrast, the salicylidene acylhydrazide INP0010 and the benzimidazole omeprazole prevent virulence factor-mediated replication of S. Typhimurium in these cells. Here we show that INP0010 enhances expression of inducible nitric oxide synthase (iNOS), nitric oxide (NO) production, the oxidative burst and tumour necrosis factor-alpha (TNF alpha) release in infected RAW264.7 cells. INP0010 also inhibited SPI2 activity in RAW264.7 cells. The ability of INP0010 to suppress bacterial intracellular replication correlated with NO production. The iNOS inhibitor N-monomethyl-L-arginine restored SPI2 activity and antagonised the bacteriostatic effect of INP0010. Omeprazole, which inhibited iNOS expression in RAW264.7 cells, likewise antagonised INP0010. In infected epithelioid MDCK cells that did not express NO upon infection, INP0010 enhanced bacterial intracellular replication. In Caenorhabditis elegans, INP0010 significantly attenuated the virulence of S. Typhimurium. In this infection model, the attenuating effect of INP0010 was further enhanced by omeprazole. These results demonstrate that chemically unrelated virulence inhibitors may act in an antagonistic or additive manner, that their effect depends on the infection model applied, and that the attenuating effects of INP0010 in part relate to its ability to promote the SPI2 antagonist NO.
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| 34. |
- Rhen, Ida-Märta, 1975, et al.
(författare)
-
A possible revival of population-representing digital human manikins in static work situations - exemplified through an evaluation of a prototype console for robotic surgery
- 2021
-
Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 70:3, s. 833-851
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In the 90s, digital human manikins (DHMs) were introduced in planning ofworkstations, by static or semi-static simulations. Modern DHMs can simulate dynamic work and offer a rapid way for a virtual pre-production ergonomic evaluation. Work-related musculoskeletal disorders may affect surgical performance and patient safety. A prototype of an open console, which is contrary to the conventional closed consoles and may be seen as a representative for a new generation, has been designed to reduce workload for robotic surgery surgeons. OBJECTIVE: The aim of this project was to test a new DHM tool with improved usability to evaluate the ergonomics of a console of a robotic surgical system in a pre-production stage. METHODS: The DHM tool IMMA was used together with a 3D model of the prototype console. Twelve manikins who represented females and males from two national populations were introduced. Manikin-console distances, after console adjustments per manikin, were compared with a US checklist and Swedish standard for VDU work. RESULTS: The DHM tool was useful for this case, but the distances of the checklist and the standard were needed to be obtained "manually". The automatic functions of the DHM worked smoothly but were not optimized for VDU work. The prototype fulfilled most, but not all, of the ergonomic criteria of the checklist and the standard. CONCLUSIONS: There is room for improvements of the adjustable ranges of the console prototype. DHMs may facilitate rapid pre-production evaluation of workstations for static work; if ergonomic assessment models for VDU work are built-in, there may be a revival of DHMs in static work situations.
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| 35. |
- Rhen, Ida-Märta, 1975, et al.
(författare)
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Ergonomic risk assessment in DHM tools employing motion data : Exposure calculation and comparison to epidemiological reference data
- 2018
-
Ingår i: International Journal of Human Factors Modelling and Simulation. - Olney : InderScience Publishers. - 1742-5549 .- 1742-5557. ; 6:1, s. 31-64
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Tidskriftsartikel (refereegranskat)abstract
- Digital human modelling (DHM) allows ergonomic risk assessment to be performed at early stages of design and development. Such assessment is typically based on observational methods, which do not take advantage of the potential of DHM tools to provide precise posture and motion data. This paper describes and illustrates an alternative assessment approach employing DHM tools, inspired by risk assessment based on direct measurements. A literature survey established a reference database of epidemiological associations between exposure and wrist-related disorders. This approach is illustrated by a DHM simulation of a car assembly task. Wrist posture and motion were simulated and compared to the database, predicting the prevalence of work-related musculoskeletal disorders on the basis of direct measurements.
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| 36. |
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| 37. |
- Rhén, Ida-Märta
(författare)
-
Ergonomics risk assessment methods for creating healthy work environments
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Risk assessments of ergonomic conditions in pre-production and in field are necessary to prevent work-related musculoskeletal disorders and to increase productivity and quality. Methods for such assessments include simulations, direct measurements and observations. In order to carry out correct ergonomic assessments, which is an important part in the work of creating healthy workplaces, it is vital that these methods are user-friendly, accurate and reliable. However, several methods are insufficiently tested with respect to these factors.The aim of this thesis was to increase the knowledge of some relevant risk assessment methods for the prevention of musculoskeletal disorders. The methods include risk assessments in both planned and existing work environments.A risk assessment approach for digital human modelling was developed. The approach included a reference database of epidemiological relationships between directly measured exposure and related musculoskeletal disorders. For illustration, a case in manual assembly was simulated; exposures were calculated and compared to the reference data to indicate the risk of work-related musculoskeletal disorders. The application and detailed assessment would be helpful to prioritise among different design solutions.A 3D digital prototype of a laparoscopic robotic open console was ergonomically evaluated using the simulation tool Intelligently Moving MAnikins (IMMA); twelve manikins representing anthropometries of the Swedish and US populations were used. The work-ranges of the console and the manikins were calculated and compared. The ergonomics was evaluated using a US checklist and the Swedish standard for computer work. The assessment criteria, which are related to the adjustability of the screen, the armrests, and the pedals, were not fulfilled. The result showed that IMMA, with its built-in functions, provides the opportunity for risk assessment of planned static work tasks. With some improvements, tools like IMMA may increasingly be used efficiently for early assessments of planned products or work environments.The inter- and intra-rater reliability and validity of six observation-based assessment methods, ART, HARM, SI, QEC, OCRA and SWEA, were studied through twelve ergonomists' and an expert group's repeated risk assessments of ten videotaped tasks. The results showed a low to moderate inter- and intra-rater reliability. Both the percent agreement and the reliability differed for the assessments of the methods' overall risk levels. Using a standardised task duration of 3.75 hours (rather than different durations for the different tasks) in the statistical calculations, the reliability of all methods decreased, except for OCRA. The decrease was most evident for HARM and ART, which was due to the fact that the duration of the task has a large impact in the methods' calculation of the total risk level. The validity was similar to the inter-rater reliability for each method.This thesis emphasizes the importance of detailed quantification of exposure and reliable methods to draw accurate conclusions about the risk of musculoskeletal disorders, both in planned and existing work environments.Today's technology, with small and wireless devices for direct measurements and methods for analysing physical exposure, provides opportunities to perform accurate and reliable ergonomic assessments. The possibility of using similar measurement strategies in digital human modelling, allows the discrimination of small differences in exposure which simplifies comparisons of different design solutions as well as between planned and existing work environment. Although the reliability of several observation-based methods was found to be low, observational methods are still important in the risk assessments of physical exposure, in order to include parts of the work environment that are not yet possible to measure. However, observational methods should preferably be used for screening and in combination with technical measurements.
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| 38. |
- Rhen, Ida-Märta, 1975, et al.
(författare)
-
Inter- and intra-rater reliability of the OCRA checklist method in video-recorded manual work tasks
- 2020
-
Ingår i: Applied Ergonomics. - : Elsevier Ltd. - 0003-6870 .- 1872-9126. ; 84
-
Tidskriftsartikel (refereegranskat)abstract
- Observation-based risk assessments are often used for evaluation of biomechanical workload and the condition of the workplace ergonomics. However, the inter- and intra-rater reliability of the methods used for the assessments are insufficiently studied. The OCRA checklist method, included as a reference method in the ISO and CEN standards regarding upper limb repetitive risk assessment, was in this study investigated regarding its reliability. Eleven ergonomists were educated within the method. Each ergonomist risk-assessed ten video-recorded manual work tasks, on two occasions. The average inter-rater agreement of the five overall risk levels was 39% and the linearly weighted kappa was 0.43, the intra-rater dittos were 45% and 0.52. Both indicating a moderate reliability, but lower than what could be expected. The levels might be sufficient for coarse surveys. However, for risk assessments before and after an intervention, complementing technical methods should be considered.
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| 39. |
- Rhén, I M, et al.
(författare)
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OCRA inter-and intra-ergonomist reliability in ten video recorded work tasks
- 2015
-
Ingår i: Proceedings 19th Triennial Congress of the IEA, Melbourne.
-
Konferensbidrag (refereegranskat)abstract
- In occupational health services (OHS) observation-based risk assessment methods are generally accepted as an objective mean for evaluation of exposure. The assessments are normally performed by well-trained ergonomists and based on real time observations or observing video recordings. According to a review of 30 assessment methods (Takala et al. 2010), several methods were insufficient tested for validity and reliability. Furthermore, OHS have called for systematic and scientifically based methods that are user friendly and cost effective (Andersson et al. 2006). The OCRA (Occupational Repetitive Actions) method is included as a reference method in ISO (ISO 11228-3) and CEN (1005-5) standards regarding risk assessment of upper limb repetitive actions. It includes time-based exposure variables such as recovery and frequency, and is more comprehensive than most other methods. Moreover, the final risk score, that predict the risk of developing musculoskeletal disorders, is based on epidemiological research (Colombini 1998, Occhipinti 1998). In the present paper, the OCRA checklist (Occhipinti and Colombini 2006) is used, which is a simplified version of the more comprehensive OCRA index. The method may be a seen as a suitable alternative for OHS-ergonomists. However, the method is not commonly used in Sweden and it has not until now been translated to Swedish. Moreover, validity and reliability studies are limited. The purpose of the present study was to examine the reliability of the OCRA checklist assessed by experienced ergonomist in a broad range of occupational situations. The objectives were to, with respect to exposure variables and the calculated risk level, estimate the consistency of 1) assessments performed by different ergonomists (inter-rater reliability) and 2) repeated assessments performed by one and the same ergonomist (intra-rater reliability) of the OCRA checklist.
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| 40. |
- Rhen, Mikael
(författare)
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Salmonella and Reactive Oxygen Species : A Love-Hate Relationship
- 2019
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Ingår i: Journal of Innate Immunity. - : S. Karger. - 1662-811X .- 1662-8128. ; 11:3, s. 216-226
-
Forskningsöversikt (refereegranskat)abstract
- Salmonella enterica represents an enterobacterial species including numerous serovars that cause infections at, or initiated at, the intestinal epithelium. Many serovars also act as facultative intracellular pathogens with a tropism for phagocytic cells. These bacteria not only survive in phagocytes but also undergo de facto replication therein. Phagocytes, through the activities of phagocyte NADPH-dependent oxidase and inducible nitric oxide synthase, are very proficient in converting molecular oxygen to reactive oxygen (ROS) and nitrogen species (RNS). These compounds represent highly efficient effectors of the innate immune defense. Salmonella is by no means resistant to these effectors, which may stand in contrast to the host niches chosen. To cope with this paradox, these bacteria rely on an array of detoxification and repair systems. Combination these systems allows for a high enough tolerance to ROS and RNS to enable establishment of infection. In addition, salmonella possesses protein factors that have the potential to dampen the infection-associated inflammation, which evidently results in a reduced exposure to ROS and RNS. This review attempts to summarize the activities and strategies by which salmonella tries to cope with ROS and RNS and how the bacterium can make use of these innate defense factors.
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| 41. |
- Stenmark, Stephan, 1965-
(författare)
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Cutaneous resistance against Francisella tularensis
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Francisella tularensis, the causative agent of tularemia, is a potent pathogen in humans and other mammals. The ulceroglandular form of the disease is the most common expression in humans with a clinical picture characterized by a skin ulcer, enlarged regional lymph nodes and fever. Despite being a preferred route of infection, the skin also affords an effective defense barrier against F. tularensis. Doses required to induce infection by intradermal inoculation are several logs higher than those needed for infection by other routes. In the present thesis, the requirements for the local and systemic host defense to intradermal infection with F. tularensis was studied in experimental mouse models. Naïve mice and mice immunized by previous infection were challenged, mostly with the live vaccine strain F. tularensis LVS but also with a clinical isolate of F. tularensis. In naïve mice, intradermal inoculation of F. tularensis LVS resulted in a rapid increase of bacterial numbers during the first few days in the skin, lymph nodes, spleen and liver, followed by a decrease and eradication of the bacteria within two weeks of inoculation. Immune mice controlled the infection at the site of infection and very few bacteria spread to internal organs. When immunohistochemical staining of skin specimens was performed during the first 3 days, naïve mice showed a weak or barely discernible local expression of TNF-α, IL-12 and IFN-γ. In immune mice, the expression of all three cytokines was strongly enhanced, TNF-α and IL-12 within 24 h and IFN-γ within 72 h of inoculation. To investigate the role of T cells in the defense against intradermal infection with F. tularensis LVS, naïve and immune T-cell knockout mice (e.g., αβ TCR-/-, γδ TCR-/-, αβγδ TCR-/-) were used. Naïve mice lacking the αβ TCR had persistently high bacterial numbers in all organs and died at 4 weeks. Mice lacking the γδ TCR, on the other hand, controlled the infection as effectively as did wild-type mice. To enable αβ TCR-/- and αβγδ TCR-/- mice to survive, antibiotic treatment was given from day 10 to 20 of infection. When intradermally challenged 2 weeks later, these animals were found to control a secondary infection, resulting in decreasing viable counts in skin and lymph nodes and prevention of spread to liver and spleen. The results indicated the presence of a T-cell independent mechanism of resistance and analyses of serum showed high levels of F. tularensis-specific IgM, findings suggesting a role for antibodies in the protection against cutaneous tularemia. To study the effect of F. tularensis-specific antibodies on host resistance, we adoptively transferred immune serum to B-cell-deficient mice. After receiving immune serum, both naïve and immunized mice became capable of surviving an otherwise lethal dose of F. tularensis LVS. Moreover, transfer of immune serum to wild type mice, afforded significant protection to a lethal dose of a wild-type strain of F. tularensis subsp. holarctica, as disclosed by reduced bacterial counts in spleen and liver. Finally, we studied the effect of immune serum on the local expression of proinflammatory cytokines and neutrophils in response to an intradermal injection of F. tularensis LVS. As compared to normal serum, transfer of immune serum resulted in increased expression of TNF-α, IL-12 and neutrophils. These findings afford a possible explanation for the effect of specific antibodies in the local host protection in the skin against tularemia.
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| 42. |
- Sun, Song, et al.
(författare)
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Genetic analysis of colistin resistance in Salmonella enterica serovar Typhimurium
- 2009
-
Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 53:6, s. 2298-2305
-
Tidskriftsartikel (refereegranskat)abstract
- Colistin is a cyclic cationic peptide that kills gram-negative bacteria by interacting with and disrupting the outer membrane. We isolated 44 independent mutants in Salmonella enterica serovar Typhimurium with reduced susceptibility to colistin and identified 27 different missense mutations located in the pmrA and pmrB genes (encoding the regulator and sensor of a two-component regulatory system) that conferred increased resistance. By comparison of the two homologous sensor kinases, PmrB and EnvZ, the 22 missense mutations identified in pmrB were shown to be located in four different structural domains of the protein. All five pmrA mutations were located in the phosphate receiver domain of the regulator protein. The mutants appeared at a mutation rate of 0.6 x 10(-6) per cell per generation. The MICs of colistin for the mutants increased 2- to 35-fold, and the extent of killing was reduced several orders of magnitude compared to the susceptible strain. The growth rates of the mutants were slightly reduced in both rich medium and M9-glycerol minimal medium, whereas growth in mice appeared unaffected by the pmrA and pmrB mutations. The low fitness costs and the high mutation rate suggest that mutants with reduced susceptibility to colistin could emerge in clinical settings.
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| 43. |
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| 44. |
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| 45. |
- Thay, Bernard
(författare)
-
Vesicle-mediated and free soluble delivery of bacterial effector proteins by oral and systemic pathogens
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Periodontitis, the primary cause of tooth-loss worldwide, is a bacterially induced chronic inflammatory disease of the periodontium. It is associated with systemic conditions such as cardiovascular disease (CVD). However, pathogenic mechanisms of periodontitis-associated bacteria that may contribute to the CVD association are unclear. The aim of this doctoral thesis project was to characterize bacterial mechanisms that can originate from the periodontal pocket and expose the host to multiple effector proteins, thereby potentially contributing to periodontal tissue degradation and systemic stimulation. As our main model, we have used Aggregatibacter actinomycetemcomitans, a Gram-negative species associated with aggressive forms of periodontitis, and with non-oral infections, such as endocarditis. Since Gram-positive species might be more common in periodontitis than previously believed, we have also investigated mechanisms of the multipotent bacterium, Staphylococcus aureus.Using an ex vivo insert model we showed that free-soluble surface material, released during growth by A. actinomycetemcomitans independently of outer membrane vesicles (OMVs), enhanced the expression of several proinflammatory cytokines in human whole blood. A clear LPS-independent effect suggested the involvement of effector proteins in this cytokine stimulation. This was supported by MALDI-TOF-MS and immunoblotting, which confirmed the release of GroEL and peptidoglycan-associated lipoprotein (PAL), in free-soluble form.We next demonstrated that A. actinomycetemcomitans OMVs could deliver multiple proteins including biologically active cytolethal distending toxin (CDT), a major virulence factor, into human gingival fibroblasts and HeLa cells. Using confocal microscopy, the active toxin unit, CdtB, was localized inside the nucleus of the intoxicated cells, whereas OmpA and proteins detected using an antibody specific to whole A. actinomycetemcomitans serotype a cells had a perinuclear distribution. By using a fluorescent probe, B-R18, it was shown that the OMVs fused with lipid rafts in the plasma membrane. These findings suggest that OMVs can deliver biologically active virulence factors such as CDT into susceptible cells of the periodontium. Using A. actinomycetemcomitans vesicles labeled with the lipophilic dye, PKH26, it was shown that the OMVs can be internalized into the perinuclear region of human cells in a cholesterol-dependent manner. Co-localization analysis supported that the internalized OMVs carried A. actinomycetemcomitans antigens. Inhibition assays suggested that although OMV internalization appeared to have a major role in effector protein delivery, additional interactions such as vesicle membrane fusion may also contribute. The OMVs strongly induced activation of the cytosolic pathogen recognition receptors NOD1 and NOD2 in HEK293T-cells, consistent with a role in triggering innate immunity by carrying PAMPs such as peptidoglycan into host cells.Membrane vesicles (MVs) from S. aureus were found to carry biologically active alpha-toxin, a key virulence factor, which was delivered to host cells and required for full cytotoxicity of the vesicles. Confocal microscopy analysis revealed that these MVs, similar to A. actinomycetemcomitans OMVs, interacted with HeLa cells via membrane fusion. Thus, as S. aureus is frequently found in individuals with aggressive periodontitis, MV production could have potential to contribute to the severity of tissue destruction.
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| 46. |
- Vestö, Kim, et al.
(författare)
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Muramyl Endopeptidase Spr Contributes to Intrinsic Vancomycin Resistance in Salmonella enterica Serovar Typhimurium
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The impermeability barrier provided by the outer membrane of enteric bacteria, a feature lacking in Gram-positive bacteria, plays a major role in maintaining resistance to numerous antimicrobial compounds and antibiotics. Here we demonstrate that mutational inactivation of spr, coding for a muramyl endopeptidase, significantly sensitizes Salmonella enterica serovar Typhimurium to vancomycin without any accompanying apparent growth defect or outer membrane destabilization. A similar phenotype was not achieved by deleting the genes coding for muramyl endopeptidases MepA, PbpG, NlpC, YedA, or YhdO. The spr mutant showed increased autolytic behavior in response to not only vancomycin, but also to penicillin G, an antibiotic for which the mutant displayed a wild-type MIC. A screen for suppressor mutations of the spr mutant phenotype revealed that deletion of tsp (prc), encoding a periplasmic carboxypeptidase involved in processing Spr and PBP3, restored intrinsic resistance to vancomycin and reversed the autolytic phenotype of the spr mutant. Our data suggest that Spr contributes to intrinsic antibiotic resistance in S. Typhimurium without directly affecting the outer membrane permeability barrier. Furthermore, our data suggests that compounds targeting specific cell wall endopeptidases might have the potential to expand the activity spectrum of traditional Gram-positive antibiotics.
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| 47. |
- Wrande, Marie
(författare)
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Growth in Aging Colonies : The Importance of Being Different
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The accumulation of rifampicin resistant (RifR) mutants in aging bacterial colonies has previously been attributed to stress-induced mutagenesis. Mutations giving rise to RifR are located in the rpoB gene, coding for the β subunit of RNA polymerase, RpoB. We showed that these mutants accumulate because they grow faster than the wild-type in the aging colonies. We found no evidence of increased mutagenesis in the RifR cells and their distribution, as localized clones in the aging colonies, indicated that they accumulated by selection and growth rather than by an increased rate of mutagenesis. Colony competition experiments with reconstructed strains showed that the RifR mutations were responsible for the growth advantage. We also found that deletion of rpoS, coding for the stationary phase sigma factor (RpoS), also gives a growth advantage on bacterial cells in aging colonies.We suggest that mutants lacking RpoS, having a different transcription pattern than the wild-type, may override the signals to enter stationary phase together with the rest of the population and instead keep growing for as long as possible. We found that the rpoB mutants mimicked the transcription pattern of the rpoS deletion mutant, thereby displaying a similar phenotype in the aging colonies. The pathways used in acetate metabolism (consisting of the enzymes Acs, AckA-Pta, PoxB and AceBAK) were shown to be important for the growth advantage mutants suggesting that acetate is one of the main carbon sources used to support their prolonged growth in the aging colonies.Rifampicin is a first-line drug used to treat M. tuberculosis infections. We used S. enterica as a model system for experimental evolution to ask whether compensatory mutations might be important in RifR mutants. In every lineage evolved compensatory mutations arose without any significant reduction in resistance. These mutations altered genes for the α, β, and β’ subunits of RNA polymerase.
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| 48. |
- Wrande, Marie, et al.
(författare)
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Replication of Salmonella enterica serovar Typhimurium in RAW264.7 Phagocytes Correlates With Hypoxia and Lack of iNOS Expression
- 2020
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Ingår i: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media S.A.. - 2235-2988. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Salmonella infection associates with tissue hypoxia, while inducible nitric oxide synthase (iNOS), relying for its activity on molecular oxygen, stands as a central host defence measure in murine salmonellosis. Here, we have detailed hypoxia and iNOS responses of murine macrophage-like RAW264.7 cells upon infection with Salmonella enterica serovar Typhimurium. We noted that only a proportion of the infected RAW264.7 cells became hypoxic or expressed iNOS. Heavily infected cells became hypoxic, while in parallel such cells tended not to express iNOS. While a proportion of the infected RAW264.7 cells revealed shutdown of protein synthesis, this was only detectable after 12 h post infection and after iNOS expression was induced in the cell culture. Our data implicate an intrinsic heterogeneity with regard to hypoxia and iNOS expression in a cell culture-based infection setting.
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