| 51881. |
- Mathisen, Peter, et al.
(författare)
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Francisella tularensis subspecies holarctica´s adaptation to protozoan and mammal hosts
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The long co-existence of bacteria and protozoa in natural ecosystems has led to the evolution of different bacterial predation-resistance mechanisms1, which in turn may have triggered development of mammal pathogens2, such as the tularemia bacterium Francisella tularensis3. We studied links between environmental persistence and pathogenicity of Francisella tularensis subsp. holarctica (F. t. holarctica), by comparing its growth in association with an aquatic amoeba and a murine macrophage. A virulent wild-type strain and four isogenic mutations with different functional protein deletions were compared; DsbA4, 5 a membrane lipoprotein with disulfide oxidoreductase activity important for proper folding in Francisella tularensis; Hfq6 a pleiotropic regulatory RNA binding protein; PilA7, 8 a type IV pilus subunit and PglA9 a protein involved in O-linked protein glycosylation. DsbA was found to be essential for bacterial growth in association with both amoeba and macrophage, while PglA did not affect bacterial persistence in any of the hosts. Absence of PilA and Hfq had marked negative effect on the bacterial cell counts in amoeba, while growth was only slightly impaired in the macrophage. Functional similarities for bacterial persistence in both hosts highlight eco-evolutionary links between persistence of intracellular pathogenic bacteria in aquatic systems and mammal hosts.
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| 51882. |
- Mathisen, Peter, et al.
(författare)
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Rapid adaptation of predation resistance in bacteria isolated from a seawater microcosm
- 2016
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Ingår i: Aquatic Microbial Ecology. - : Inter-Research Science Center. - 0948-3055 .- 1616-1564. ; 78:2, s. 81-92
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial defense against protozoan grazing has been shown to occur in many different bacteria. Predation resistance traits may however be plastic, making bacterial com munities resilient or resistant to predation perturbations. We studied the adaptation of pre dation resistance traits in bacteria isolated from a microcosm experiment. In the initial microcosm ex periment the predation pressure on bacteria varied markedly, while changes in the bacterial community composition could not be verified. Seven bacteria were isolated from the microcosm (Micrococcus sp., Rhodobacter sp., Paracoccus sp., Shewanella sp., Rhizobium sp. and 2 un identified species) and these were repeatedly exposed to high predation by the ciliate Tetrahymena pyriformis. High variations in edibility and rate of adaptation of predation resistance traits were observed among the strains. The initial mortality rate of the different bacterial taxa and the change over time varied by a factor of 7 and 24, respectively. Rhodobacter sp. was already predation resistant at the start of the experiment and did not change much over time, while Micrococcus sp., Paracoccus sp. and Shewanella sp. initially were relatively edible and later developed predation resistance. In conclusion, we show that rapid adaptation of predation resistance traits is common among bacteria in an aquatic microbial community, and that a single test of a bacterium’s edibility will in many cases not be enough to fully understand its ecological role, as it will not reveal the potential adaptive response. The results suggest the potential of rapid changes of predation resistance as a mechanism for bacterial communities to be resilient to variations in predation disturbances.
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| 51883. |
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| 51884. |
- Matiko, Mirende Kichuki, et al.
(författare)
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Serological evidence of inter-epizootic/interepidemic circulation of Rift Valley fever virus in domestic cattle in Kyela and Morogoro, Tanzania
- 2018
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Ingår i: PLoS Neglected Tropical Diseases. - San Francisco : Public Library of Science. - 1935-2727 .- 1935-2735. ; 12:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tanzania is among the Rift Valley fever (RVF) epizootic/endemic countries in sub Saharan Africa, where RVF disease outbreaks occur within a range of 3 to 17-year intervals. Detection of Rift Valley fever virus (RVFV) antibodies in animals in regions with no previous history of outbreaks raises the question of whether the disease is overlooked due to lack-of effective surveillance systems, or if there are strains of RVFV with low pathogenicity. Furthermore, which vertebrate hosts are involved in the inter-epidemic and inter-epizootic maintenance of RVFV? In our study region, the Kyela and Morogoro districts in Tanzania, no previous RVF outbreaks have been reported.Methodology: The study was conducted from June 2014 to October 2015 in the Kyela and Morogoro districts, Tanzania. Samples (n = 356) were retrieved from both the local breed of zebu cattle (Bos indicus) and Bos indicus/Bos Taurus cross breed. RVFV antibodies were analyzed by two enzyme-linked immunosorbent assay (ELISA) approaches. Initially, samples were analyzed by a RVFV multi-species competition ELISA (cELISA), which detected both RVFV IgG and IgM antibodies. All serum samples that were positive with the cELISA method were specifically analysed for the presence of RVFV IgM antibodies to trace recent infection. A plaque reduction neutralization assay (PRNT80) was performed to determine presence of RVFV neutralizing antibodies in all cELISA positive samples.Findings: Overall RVFV seroprevalence rate in cattle by cELISA in both districts was 29.2% (104 of 356) with seroprevalence rates of 33% (47/147) in the Kyela district and 27% (57/209) in the Morogoro district. In total, 8.4% (30/356) of all cattle sampled had RVFV IgM antibodies, indicating current disease transmission. When segregated by districts, the IgM antibody seroprevalence was 2.0% (3/147) and 12.9% (27/209) in Kyela and Morogoro districts respectively. When the 104 cELISA positive samples were analyzed by PRNT80 to confirm that RVFV-specific antibodies were present, the majority (89%, 93/104) had RVFV neutralising antibodies.Conclusion: The results provided evidence of widespread prevalence of RVFV antibody among cattle during an inter-epizootic/inter-epidemic period in Tanzania in regions with no previous history of outbreaks. There is a need for further investigations of RVFV maintenance and transmission in vertebrates and vectors during the long inter-epizootic/inter-epidemic periods.
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| 51885. |
- Matilda, Rentoft, 1981-
(författare)
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The use of formalin fixed paraffin embedded tissue and global gene expression profiling for increased understanding of squamous cell carcinoma of the tongue
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Head and neck cancer is the 6th most common malignancy worldwide, with tumours of the tongue being one of the most prevalent sites. Despite advances in surgery and radiotherapy, the five-year survival has not changed during the last decades and remains at approximately 50%. Identification of novel biomarkers for more personalized treatment is important for increasing survival in these patients. One of the most commonly used methods in the search for new biomarkers is microarray analysis. A substantial limitation with this technique is the requirement for fresh frozen samples from which high quality RNA can be extracted. This becomes particularly problematic when attempting to discover differences associated with individual sub-types or rare cancers. Recent developments, including the DASL microarray platform, have provided the possibility of analysing RNA of poorer quality from formalin fixed paraffin embedded (FFPE) samples. FFPE is the standard way of preserving tissue from patients and millions of samples are stored around the world. In this thesis we have evaluated the use of FFPE samples and global gene expression profiling for increasing basic knowledge in a subgroup of oral cancer patients with tumours of the tongue. As confirmation of microarray results using qPCR is of outmost importance for conclusive data evaluation, we first aimed at finding a housekeeping gene stably expressed across malignant and non-malignant FFPE oral tissue. TUBA6, which belongs to the tubulin family was detected as being the most stable out of eight possible genes and was thus used for qPCR normalization throughout the following studies. We have performed three separate microarray experiments. Initially only a focused DASL array covering 502 cancer related genes was available and we used it to analyze a smaller cohort of patients and controls (n=36). A similar cohort (n=29) was also analyzed for expression of 836 micoRNAs. In 2009 a whole genome DASL array was launched, covering over 20,000 genes, and all tongue tumour samples available between 1997 and 2010 (n=87) were analysed using this array. Similar to other research groups we observed very high replicate reproducibility using both DASL arrays. When using the microRNA array and the whole genome DASL array an effect of sample quality on the detected expression level of individual genes was noticed. While the expression of some genes severely decreased with a decrease in sample quality others were not changed. This will impair normalization, leading to a residual non-biological variation within the data. Based on our findings we have presented some recommendations for minimizing the effect of sample quality and maximizing the level of biologically relevant information obtained from these experiments, e.g. ensuring that samples in groups to be compared are of the same quality range. For the microRNA data we also introduced an additional normalization step to the standard normalizations. We could show that lists of differentially expressed genes generated when taking these precautions were enriched for genes involved in cancer related processes and contained for tongue carcinoma previously identified changes. A number of differentially expressed genes, novel for tongue carcinoma, were also confirmed in high quality fresh frozen samples, including BCL2A1 (apoptosis), CXCL10 (immune response), SLC2A6 (energy transport) and miR-424 (angiogenesis). In conclusion microarrays can be used to analyze FFPE samples but should be performed with care. Standard normalization methods will not remove the variation introduced by samples being of different quality, leading to spurious results. Taking a few precautions, however, led to the identification of differentially expressed genes relevant in tumour development and maintenance. The recommendations we make can facilitate design of future studies using FFPE samples. The genes we identified as being differentially expressed in tumour tissue now need to be further evaluated for their potential as biomarkers in tongue carcinoma.
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| 51886. |
- Matin, Mohammad Abdul, et al.
(författare)
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What influences antibiotic sales in rural Bangladesh? : A drug dispensers' perspective
- 2020
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Ingår i: Journal of Pharmaceutical Policy and Practice. - : Springer Nature. - 2052-3211. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Antibiotic resistance poses a great threat to global health, especially in low- and middle-income countries with a high infectious disease burden and limited resources. In spite of regulations, antibiotics are sold in many settings as non-prescription medicines, resulting in inappropriate use and resistance.Objective: This study aimed to investigate the current status of access and use of antibiotics in rural Bangladesh, by exploring the perspectives and sales practices of antibiotic drug dispensers.Methods: We used a mixed methods approach (qualitative and quantitative). We mapped and characterized antibiotic purchasing and dispensing sites in the Matlab Health and Demographic Surveillance System catchment area. Furthermore, we investigated the volume of provision of systemic antibiotics in 10 drug outlets. We held 16 in-depth interviews with randomly selected antibiotics dispensers. Interviews explored factors associated with antibiotic selling. Responses were transcribed, coded for themes, and summarized. We used ATLAS.ti 5.2 for conducting a thematic analysis.Results: A total of 301 antibiotic dispensers were identified, of whom 92% (n = 278) were private and 8% (n = 23) public. 52% (n = 155) operated informally (i.e. without legal authorization). In order to promote and survive in their business, dispensers sell antibiotics for a range of conditions without a qualified physician's prescription. Factors that facilitate these inappropriate sales include lack of access to healthcare in the rural community, inadequate doctor: population ratio, limited dispenser knowledge, poor pharmacovigilance concerning safety of self medication, lack of enforcement of policies, financial benefits for both customers and dispensers, and high dependency on pharmaceutical companies' information.Conclusion: Dispensers in rural Bangladesh sell antibiotics inappropriately by ignoring existing national regulations. They operate the antibiotic sales without facing any legal barriers and primarily with a view to sustain their business, resulting in inappropriate sales of antibiotics to the rural community. The influence of the drug industry needs to be replaced with evidence-based, not commercially driven information. Awareness programs for antibiotic providers that promote understanding of antibiotics and antibiotic resistance through tailored interventions may be helpful in changing current antibiotic sales practices.
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| 51887. |
- Matosic, Doris, et al.
(författare)
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Linking Narcissism, Motivation, and Doping Attitudes in Sport : A Multilevel Investigation Involving Coaches and Athletes
- 2016
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Ingår i: Journal of Sport & Exercise Psychology (JSEP). - : HUMAN KINETICS PUBL INC. - 0895-2779 .- 1543-2904. ; 38:6, s. 556-566
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Tidskriftsartikel (refereegranskat)abstract
- Research on coaching (Bartholomew, Ntoumanis, & Thogersen-Ntoumani, 2009) has shown that coaches can display controlling behaviors that have detrimental effects on athletes' basic psychological needs and quality of sport experiences. The current study extends this literature by considering coach narcissism as a potential antecedent of coaches' controlling behaviors. Further, the study tests a model linking coaches' (n = 59) own reports of narcissistic tendencies with athletes' (n = 493) perceptions of coach controlling behaviors, experiences of need frustration, and attitudes toward doping. Multilevel path analysis revealed that coach narcissism was directly and positively associated with athletes' perceptions of controlling behaviors and was indirectly and positively associated with athletes' reports of needs frustration. In addition, athletes' perceptions of coach behaviors were positively associated directly and indirectly with attitudes toward doping. The findings advance understanding of controlling coach behaviors, their potential antecedents, and their associations with athletes' attitudes toward doping.
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| 51888. |
- Matousek, T, et al.
(författare)
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Gas flow patterns and longitudinal distribution of free selenium atoms in quartz tube atomizers for hydride generation atomic absorption spectrometry
- 2000
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Ingår i: Spectrochimica Acta Part B: Atomic Spectroscopy. ; 55:2, s. 151-63
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Tidskriftsartikel (refereegranskat)abstract
- Gas flow patterns in unheated quartz tube hydride atomizers were studied by light scattering on ammonium chloride particles and by observation of iodine vapors. The flow pattern is basically laminar, with a turbulent region at the T-junction and irregularities at the tube ends. We studied the free atom distribution over the length of the atomizers optical bar under various conditions by measuring the selenium signal with the tube perpendicular to the radiation beam, through the tube walls. In the whole range of atomization conditions used (Se 60-400 g l-1, 0.8-2 l min-1 of H2 as purge gas, 0-50 ml min-1 O2,), there is a sharp maximum of free atom concentration in the tube centre, and all the free atoms disappear before they reach the tube ends. The absorption profiles are essentially the same in unheated as in flame-heated tubes, and there is no difference between heated flame-in-tube and externally heated arrangement. With decreasing purge gas flow rate, free atoms occupy a shorter part of the tube. Free atoms start to decay immediately after entering the optical tube of the atomizer. In both heated and unheated atomizers, enhanced free atom decay at higher concentrations contributes to the curvature of calibration graphs. As all free atoms disappear before reaching the ends of the tube even at relatively high purge gas flow rates, it is not possible to obtain higher sensitivities by extending the atomizer length. There is no difference in the free atom distribution in the central part of the tube if oxygen is prevented to enter the tube from the ends (by quartz windows or flames burning at the tube ends), so the free atom decay is not caused by O2 diffusing from the ambient atmosphere. With flames burning on tube ends, free Se atoms were reappearing close to the ends, proving the possibility of reatomization of species formed by free atom reactions. When no measures against O2 penetration from the tube ends of the heated atomizer are taken, signal reappearance takes place at the borders of the hot part of the atomizer, contributing substantially to the overall sensitivity. The results obtained correspond very well to the present picture of hydride atomization by H-radicals and their subsequent decay.
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| 51889. |
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| 51890. |
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