| 1. |
- Björklund, Elisabet, et al.
(författare)
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Quality control of flow cytometry data analysis for evaluation of minimal residual disease in bone marrow from acute leukemia patients during treatment.
- 2009
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Ingår i: Journal of pediatric hematology/oncology : official journal of the American Society of Pediatric Hematology/Oncology. - : Lippincott Williams & Wilkins. - 1536-3678 .- 1077-4114. ; 31:6, s. 406-15
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Tidskriftsartikel (refereegranskat)abstract
- Low levels of leukemia cells in the bone marrow, minimal residual disease (MRD), are considered to be a powerful indicator of treatment response in acute lymphatic leukemia (ALL). A Nordic quality assurance program, aimed on standardization of the flow cytometry MRD analysis, has been established before implementation of MRD at cutoff level 10 as one of stratifying parameters in next Nordic Society of Pediatric Hematology and Oncology (NOPHO) treatment program for ALL. In 4 quality control (QC) rounds 15 laboratories determined the MRD levels in 48 follow-up samples from 12 ALL patients treated according to NOPHO 2000. Analysis procedures were standardized. For each QC round a compact disc containing data in list-mode files was sent out and results were submitted to a central laboratory. At cutoff level 10, which will be applied for clinical decisions, laboratories obtained a high concordance (91.6%). If cutoff level 10 was applied, the concordance would be lower (85.3%). The continuing standardization resulted in better concordance in QC3 and QC4 compared with QC1 and QC2. The concordance was higher in precursor B as compared with T-cell ALL. We conclude that after standardization, flow cytometry MRD detection can be reliably applied in international, multicenter treatment protocols.
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| 2. |
- Bodnar, Taras, et al.
(författare)
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Tangency portfolio weights for singular covariance matrix in small and large dimensions : estimation and test theory
- 2019
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Ingår i: Journal of Statistical Planning and Inference. - : Elsevier. - 0378-3758 .- 1873-1171. ; 201, s. 40-57
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we derive the finite-sample distribution of the estimated weights of the tangency portfolio when both the population and the sample covariance matrices are singular. These results are used in the derivation of a statistical test on the weights of the tangency portfolio where the distribution of the test statistic is obtained under both the null and the alternative hypotheses. Moreover, we establish the high-dimensional asymptotic distribution of the estimated weights of the tangency portfolio when both the portfolio dimension and the sample size increase to infinity. The theoretical findings are implemented in an empirical application dealing with the returns on the stocks included into the S&P 500 index.
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| 3. |
- Donis, Daphne, et al.
(författare)
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Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer
- 2021
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:12, s. 4314-4333
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Tidskriftsartikel (refereegranskat)abstract
- To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.
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| 4. |
- Gupta, Monali, et al.
(författare)
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Radar plots facilitate differential diagnosis of acute promyelocytic leukemia and NPM1+ acute myeloid leukemia by flow cytometry
- 2021
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Ingår i: Cytometry Part B - Clinical Cytometry. - : Wiley. - 1552-4949 .- 1552-4957. ; 100:4, s. 409-420
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Tidskriftsartikel (refereegranskat)abstract
- Background: Acute promyelocytic leukemia (APL) is one of the most life-threatening hematological emergencies and requires a prompt correct diagnosis by cytomorphology and flow cytometry (FCM) with later confirmation by cytogenetics/molecular genetics. However, nucleophosmin 1 muted acute myeloid leukemia (NPM1+ AML) can mimic APL, especially the hypogranular variant of APL. Our study aimed to develop a novel, Radar plot-based FCM strategy to distinguish APLs and NPM1+ AMLs quickly and accurately. Method: Diagnostic samples from 52 APL and 32 NPM1+ AMLs patients were analyzed by a 3-tube panel of 10-color FCM. Radar plots combining all markers were constructed for each tube. Percentages of positive leukemic cells and mean fluorescence intensity were calculated for all the markers. Results: APL showed significantly higher expression of CD64, CD2, and CD13, whereas more leukemic cells were positive for CD11b, CD11c, CD15, CD36, and HLA-DR in NPM1+ AMLs. Radar plots featured CD2 expression, a lack of a monocytic component, lack of expression of HLA-DR and CD15, and a lack of a prominent CD11c+ population as recurring characteristics of APL. The presence of blasts with low SSC, presence of at least some monocytes, some expression of HLA-DR and/or CD15, and a prominent CD11c population were recurrent characteristics of NPM1+ AMLs. Radar plot analysis could confidently separate all hypergranular APL cases from any NPM1+ AML and in 90% of cases between variant APL and blastic NPM1+ AML. Conclusion: Radar plots can potentially add to differential diagnostics as they exhibit characteristic patterns distinguishing APL and different types of NPM1+ AMLs.
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| 5. |
- Mantzouki, Evanthia, et al.
(författare)
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Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins
- 2018
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Ingår i: Toxins. - : MDPI. - 2072-6651. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.
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| 6. |
- Mazur, Joanna, et al.
(författare)
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Trends in multiple health complaints in Polish adolescents in light of data from 30 European countries and Canada (2002-2018)
- 2021
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Ingår i: Journal of Mother and Child. - : Walter de Gruyter. - 2719-535X. ; 25:1, s. 25-34
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Tidskriftsartikel (refereegranskat)abstract
- Background: Adolescence is a sensitive period accompanied by rapid developmental changes that can result in health complaints. The aim of the study was to describe the trend of subjective health complaints (HBSC-SCL) of Polish adolescents compared to their peers from 30 other countries and to rank all countries based on a proposed standardised measure.Material and Methods: Data from the Health Behaviour in School-Aged Children (HBSC) study collected from 2002 to 2018 were used. The overall number of respondents from 30 countries in the combined sample from five quadrennial rounds was 773,356, including 49.2% boys and 50.8% girls. The HBSC-SCL is a non-clinical measure consisting of eight health complaints, usually analysed in two dimensions of psychological and somatic symptoms. Linear regression analysis was applied to assess the significance of trends of the total index and two subindices in the combined sample and individual countries.Results: A significant increasing trend for the eight-item index appeared in Poland only in 13- and 15-year-olds, while only among 15-year-olds in the combined sample from 30 countries. Standardised country rank varied between -1.85 and 2.48 (worst). The countries that achieved extreme negative values (>=1) are France, Hungary, Italy, and Sweden, and the rank for Italy is considerably higher than for other countries. In Poland, the standardised rank for psychological symptoms exceeded the threshold of +1 in 2018.Conclusions: The HBSC-SCL index could be useful for monitoring change in adolescent mental health. The proposed method of ranking may allow a broader view of the differences and similarities between countries and help to identify those performing unfavourably against cross-country patterns.
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| 7. |
- Omadjela, Okako, et al.
(författare)
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BcsA and BcsB form the catalytically active core of bacterial cellulose synthase sufficient for in vitro cellulose synthesis
- 2013
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 110:44, s. 17856-17861
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose is a linear extracellular polysaccharide. It is synthesized by membrane-embedded glycosyltransferases that processively polymerize UDP-activated glucose. Polymer synthesis is coupled to membrane translocation through a channel formed by the cellulose synthase. Although eukaryotic cellulose synthases function in macromolecular complexes containing several different enzyme isoforms, prokaryotic synthases associate with additional subunits to bridge the periplasm and the outer membrane. In bacteria, cellulose synthesis and translocation is catalyzed by the inner membrane-associated bacterial cellulose synthase (Bcs) A and BcsB subunits. Similar to alginate and poly-beta-1,6 N-acetylglucosamine, bacterial cellulose is implicated in the formation of sessile bacterial communities, termed biofilms, and its synthesis is likewise stimulated by cyclic-di-GMP. Biochemical studies of exopolysaccharide synthesis are hampered by difficulties in purifying and reconstituting functional enzymes. We demonstrate robust in vitro cellulose synthesis reconstituted from purified BcsA and BcsB proteins from Rhodobacter sphaeroides. Although BcsA is the catalytically active subunit, the membrane-anchored BcsB subunit is essential for catalysis. The purified BcsA-B complex produces cellulose chains of a degree of polymerization in the range 200-300. Catalytic activity critically depends on the presence of the allosteric activator cyclic-di-GMP, but is independent of lipid-linked reactants. Our data reveal feedback inhibition of cellulose synthase by UDP but not by the accumulating cellulose polymer and highlight the strict substrate specificity of cellulose synthase for UDP-glucose. A truncation analysis of BcsB localizes the region required for activity of BcsA within its C-terminal membrane-associated domain. The reconstituted reaction provides a foundation for the synthesis of biofilm exopolysaccharides, as well as its activation by cyclic-di-GMP.
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| 8. |
- Ottová-Jordan, Veronika, et al.
(författare)
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Trends in health complaints from 2002 to 2010 in 34 countries and their association with health behaviours and social context factors at individual and macro-level
- 2015
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Ingår i: European Journal of Public Health. - : Oxford University Press. - 1101-1262 .- 1464-360X. ; 25:2, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: This article describes trends and stability over time in health complaints in adolescents from 2002 to 2010 and investigates associations between health complaints, behavioural and social contextual factors at individual level and economic factors at macro-level.METHODS: Comprising N = 510 876 11-, 13- and 15-year-old children and adolescents in Europe, North America and Israel, data came from three survey cycles of the international Health Behaviour in School-aged Children (HBSC) study. Age- and gender-adjusted trends in health complaints were examined in each country by means of linear regression. By using the country as the random effects variable, we tested to what extent individual and contextual variables were associated with health complaints.RESULTS: Significant associations are stronger for individual level determinants (e.g. being bullied, smoking) than for determinants at macro-level (e.g. GDP, Gini), as can be seen by the small effect sizes (less than 5% for different trends). Health complaints are fairly stable over time in most countries, and no clear international trend in health complaints can be observed between 2002 and 2010. The most prominent stable determinants were being female, being bullied, school pressure and smoking.CONCLUSION: Factors associated with health complaints are more related to the proximal environment than to distal macro-level factors. This points towards intensifying targeted interventions, (e.g. for bullying) and also targeting specific risk groups. The comparably small effect size at country-level indicates that country-level factors have an impact on health and should not be ignored.
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| 9. |
- Ottová-Jordan, Veronika, et al.
(författare)
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Trends in health complaints from 2002 to 2010 in 34 countries and their association with health behaviours and social context factors at individual and macro-level
- 2015
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Ingår i: European Journal of Public Health. - : Oxford University Press. - 1101-1262 .- 1464-360X. ; 25:Suppl 2, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: This article describes trends and stability over time in health complaints in adolescents from 2002 to 2010 and investigates associations between health complaints, behavioural and social contextual factors at individual level and economic factors at macro-level.METHODS: Comprising N = 510 876 11-, 13- and 15-year-old children and adolescents in Europe, North America and Israel, data came from three survey cycles of the international Health Behaviour in School-aged Children (HBSC) study. Age- and gender-adjusted trends in health complaints were examined in each country by means of linear regression. By using the country as the random effects variable, we tested to what extent individual and contextual variables were associated with health complaints.RESULTS: Significant associations are stronger for individual level determinants (e.g. being bullied, smoking) than for determinants at macro-level (e.g. GDP, Gini), as can be seen by the small effect sizes (less than 5% for different trends). Health complaints are fairly stable over time in most countries, and no clear international trend in health complaints can be observed between 2002 and 2010. The most prominent stable determinants were being female, being bullied, school pressure and smoking.CONCLUSION: Factors associated with health complaints are more related to the proximal environment than to distal macro-level factors. This points towards intensifying targeted interventions, (e.g. for bullying) and also targeting specific risk groups. The comparably small effect size at country-level indicates that country-level factors have an impact on health and should not be ignored.
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| 10. |
- Ottová-Jordan, Veronika, et al.
(författare)
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Trends in Multiple Recurrent health complaitns in 15-year-olds in 35 countries in Europe, North America and Israel from 1994 to 2010
- 2015
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Ingår i: European Journal of Public Health. - : Oxford University Press. - 1101-1262 .- 1464-360X. ; 25:suppl 2, s. 24-27
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Health complaints are a good indicator of an individual's psychosocial health and well-being. Studies have shown that children and adolescents report health complaints which can cause significant individual burden.METHODS: Using data from the international Health Behaviour in School-aged Children study, this article describes trends in multiple recurrent health complaints (MHC) in 35 countries among N = 237 136 fifteen-year-olds from 1994 to 2010. MHC was defined as the presence of two or more health complaints at least once a week. Logistic regression analysis was performed to evaluate trends across the five survey cycles for each country.RESULTS: Lowest prevalence throughout the period 1994-2010 was 16.9% in 1998 in Austria and highest in 2006 in Israel (54.7%). Overall, six different trend patterns could be identified: No linear or quadratic trend (9 countries), linear decrease (7 countries), linear increase (5 countries), U-shape (4 countries), inverted U-shape (6 countries) and unstable (4 countries).CONCLUSION: Trend analyses are valuable in providing hints about developments in populations as well as for benchmarking and evaluation purposes. The high variation in health complaints between the countries requires further investigation, but may also reflect the subjective nature of health complaints.
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