1. |
- Andersson, Christian, et al.
(author)
-
Do you want your child to have a certified teacher?
- 2011
-
In: Economics of Education Review. - : Elsevier BV. - 0272-7757 .- 1873-7382. ; 30:1, s. 65-78
-
Journal article (peer-reviewed)abstract
- This study examines how the teaching staff composition with respect to certification affects student achievement in compulsory Swedish schools. We apply an instrumental variable to estimate the effect of the share of non-certified teachers on student achievement (measured by grade point average, GPA). We find statistically significant negative effects on the GPA. The effect is stronger for students with highly educated parents. A one percentage point increase in the share of non-certified teachers is expected to decrease student's GPA by, on average, 1.8 standard deviations per year. This is a substantial effect considering the large differences in the shares of non-certified teachers across schools and municipalities.
|
|
2. |
- Gennebäck, Nina, 1982-
(author)
-
Cardiac hypertrophy : transcription patterns, hypertrophic progression and extracellular signalling
- 2012
-
Doctoral thesis (other academic/artistic)abstract
- Background: The aim of this thesis was to study transcription patterns and extracellular signalling of the hypertrophic heart to better understand the mechanisms initiating, controlling and maintaining cardiac hypertrophy.Cardiac hypertrophy is a risk factor for cardiovascular morbidity and mortality. Hypertrophy of the myocardium is a state, independent of underlying disease, where the myocardium strives to compensate for an increased workload. This remodelling of the heart includes physiological changes induced by a changed gene expression, alteration of the extracellular matrix and diverse cell-to-cell signalling.Shedding microvesicles and exosomes are membrane released vesicles derived from the plasma membrane, which can mediate messages between cells and induce various cell-related processes in target cells.Methods and materials: Two different microarray studies on different materials were performed. In the first study, cardiac myectomies from 8 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 5 controls without cardiac disease were used. In the second study, myocardial tissue from 6 aorta ligated and 6 sham operated (controls) rats at three different time points (1, 6 and 42 days post-surgically) were analysed. To reveal differences in gene expression the materials were analyzed with Illumina whole genome microarray and multivariate data analysis (PCA and OPLS-DA).Cultured cardiomyocytes (HL-1) were incubated with and without growth factors (TGF-β2 or PDGF BB). Microvesicles and exosomes were collected and isolated after differential centrifugations and ultracentrifugations of the cell culture medium. The microvesicles and exosomes were characterized with dynamic light scattering (DLS), flow cytometry, western blot, electron microscopy and Illumina whole genome microarray.Results: The two different microarray studies revealed differentially expressed gene transcripts and groups of transcripts. When comparing HOCM patients to controls significant down-regulation of the MYH6 gene transcript and two immediate early genes (IEGs, EGR1 and FOS), as well as significant up-regulation of the ACE2, JAK2 and HDAC5 gene transcripts were found. In the rat model, 5 gene groups showed interesting clustering after multivariate data analysis (OPLS-DA) associated with the hypertrophic development: “Atherosclerosis”, “ECM and adhesion molecules”, “Fatty acid metabolism”, “Glucose metabolism” and “Mitochondria”.The shedding microvesicles were rounded vesicles, 40-300 nm in size and surrounded by a bilayered membrane. Chromosomal DNA sequences were identified in the microvesicles. The microvesicles could be taken up by fibroblasts resulting in an altered gene expression in the fibroblasts. The exosomes from cultured cardiomyocytes (incubated with TGF-β2 or PDGF BB) had an average diameter of 50-80 nm, similar to the unstimulated control exosomes. A large, for all cardiomyocyte derived exosomes, common pool of mRNA seems stable and a smaller pool varied in mRNA content according to treatment of the cardiomyocyte. Of the common mRNA about 14% were ribosomal, 14% were of unknown locus and 5% connected to the function of the mitochondria.Conclusions: The microarray studies showed that transcriptional regulation at a stable stage of the hypertrophic development is a balance of pro and anti hypertrophic mechanisms and that diverse gene groups are differently regulated at different time points in the hypertrophic progression.OPLS-DA is a very useful and powerful tool when analyzing gene expression data, especially in finding clusters of gene groups not seen with traditional statistics.The extracellular vesicle studies suggests that microvesicles and exosomes released from cardiomyocytes contain DNA and can be involved in events in target cells by facilitating an array of processes including gene expression changes. Different treatment of the cardiomyocyte influence the content of the exosome produced, indicating that the signal function of the exosome might vary according to the state of the cardiomyocyte.
|
|
3. |
- Gennebäck, Nina, 1982-, et al.
(author)
-
Growth factor stimulation of cardiomyocytes induces changes in the transcriptional contents of secreted exosomes
- 2013
-
In: Journal of Extracellular Vesicles. - : Co-Action Publishing. - 2001-3078.
-
Journal article (peer-reviewed)abstract
- Exosomes are nano-sized extracellular vesicles, released from various cells, which can stimulate or repress responses in targets cells. We recently reported that cultured cardiomyocytes are able to release exosomes and that they, in turn, are involved in facilitating events in target cells by alteration of gene expression. We investigated whether external stimuli of the cardiomyocyte might influence the transcriptional content of the released exosomes.Exosomes were isolated from media collected from cultured cardiomyocytes (HL-1) with or without growth factor treatment (TGF-β2 and PDGF-BB), with a series of differential centrifugations, including preparative ultracentrifugation and separation with a sucrose gradient. The exosomes were characterized with dynamic light scattering (DLS), electron microscopy (EM) and Western blot and analyzed with Illumina whole genome microarray gene expression.The exosomes were rounded in shape and had an average size of 50–90 nm in diameter with no difference between treatment groups. Analysis of the mRNA content in repeated experiments conclusively revealed 505 transcripts in the control group, 562 in the TGF-β2-treated group and 300 in the PDGF-BB-treated group. Common transcripts (217) were found in all 3 groups.We show that the mode of stimulation of parental cells affects the characteristics of exosomes released. Hence, there is a difference in mRNA content between exosomes derived from cultured cardiomyocytes stimulated, or not stimulated, with growth factors. We also conclude that all exosomes contain a basic package consisting of ribosomal transcripts and mRNAs coding for proteins with functions within the energy supply system.
|
|
4. |
|
|
5. |
- Gennebäck, Nina, 1982-, et al.
(author)
-
Transcriptional regulation of cardiac genes balance pro and anti hypertrophic mechanisms in hypertrophic cardiomyopathy
- 2012
-
In: Cardiogenetics. - : MDPI AG. - 2035-8148. ; 2:1
-
Journal article (peer-reviewed)abstract
- Background: Hypertrophic cardiomyopathy (HCM) is characterised by unexplained left ventricular hypertrophy. HCM is often hereditary, but the knowledge about the mechanisms leading from mutation to phenotype is incomplete. The transcriptional expression patterns in the myocardium of HCM patients may contribute to the understanding of the mechanisms that drive and stabilize the hypertrophy.Design and Methods: Cardiac myectomies/biopsies from 8 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 5 controls were studied with whole genome Illumina microarray gene expression (detecting 18 189 mRNA).Results: When comparing HOCM myocardium to controls, there was significant transcriptional down-regulation of the MYH6, EGR1, APOB and FOS genes, and significant transcriptional up-regulation of the ACE2, JAK2, NPPA (ANP), APOA1 and HDAC5genes. Conclusion: The transcriptional regulation revealed both pro and anti hypertrophic mechanisms. The pro hypertrophic response was explained by the transcriptional down-regulation of MYH6, indicating that the switch to the fetal gene program is maintained, and the transcriptional up-regulation of JAK2 in JAK-STAT pathway. The anti hypertrophic response was seen as a transcriptional down-regulation of the immediate early genes (IEGs), FOS and EGR1, and a transcriptional up-regulation of ACE2 and HDAC5. This can be interpreted as a transcriptional endogenous protection system in the heart of the HOCM patients, neither growing nor suppressing the already hypertrophic myocardium.
|
|
6. |
- Gennebäck, Nina, et al.
(author)
-
Using OPLS-DA to find new hypotheses in vast amounts of gene expression data - Studying the progression of cardiac hypertrophy in the heart of aorta ligated rat
- 2013
-
In: Gene. - : Elsevier BV. - 0378-1119 .- 1879-0038. ; 522:1, s. 27-36
-
Journal article (peer-reviewed)abstract
- One of the great problems facing science today lies in data mining of the vast amount of data. In this study we explore a new way of using orthogonal partial least squares-discrimination analysis (OPLS-DA) to analyze multidimensional data. Myocardial tissues from aorta ligated and control rats (sacrificed at the acute, the adaptive and the stable phases of hypertrophy) were analyzed with whole genome microarray and OPLS-DA. Five functional gene transcript groups were found to show interesting clusters associated with the aorta ligated or the control animals. Clustering of "ECM and adhesion molecules" confirmed previous results found with traditional statistics. The clustering of "Fatty acid metabolism", "Glucose metabolism", "Mitochondria" and "Atherosclerosis" which are new results is hard to interpret, thereby being possible subject to new hypothesis formation. We propose that OPLS-DA is very useful in finding new results not found with traditional statistics, thereby presenting an easy way of creating new hypotheses.
|
|
7. |
- Lagging, Martin, 1965, et al.
(author)
-
Reply.
- 2014
-
In: Hepatology (Baltimore, Md.). - : Ovid Technologies (Wolters Kluwer Health). - 1527-3350 .- 0270-9139. ; 60:6, s. 2130-1
-
Journal article (other academic/artistic)
|
|
8. |
- Rembeck, Karolina, et al.
(author)
-
Variants of the inosine triphosphate pyrophosphatase gene are associated with reduced relapse risk following treatment for HCV genotype 2/3.
- 2014
-
In: Hepatology (Baltimore, Md.). - : Ovid Technologies (Wolters Kluwer Health). - 1527-3350 .- 0270-9139. ; 59:6, s. 2131-2139
-
Journal article (peer-reviewed)abstract
- The present study evaluated the impact of variations in the inosine triphosphate pyrophosphatase (ITPase) gene (ITPA) on treatment outcome in patients with hepatitis C virus (HCV) genotype 2/3 infection receiving peginterferon-α2a and lower, conventional 800 mg daily dose of ribavirin. Previous studies using higher, weight-based ribavirin dosing report that patients carrying polymorphisms encoding reduced predicted ITPase activity show decreased risk of ribavirin-induced anemia but increased risk of thrombocytopenia, with no impact on elimination of virus. Three hundred fifty-four treatment naïve HCV genotype 2/3 infected patients, enrolled in a phase III trial (NORDynamIC), were genotyped for ITPA (rs1127354 and rs7270101). Homo- or heterozygosity at Ars1127354 or Crs7270101, entailing reduced ITPase activity, was observed in 37% of patients and was associated with increased likelihood of achieving sustained virological response (SVR) (P=0.0003 in univariate and multivariate analyses) accompanied by a reduced risk of relapse among treatment-adherent patients. The association between ITPA variants and SVR remained significant when patients were subdivided by the 12- and 24-week treatment duration arms, HCV genotype, fibrosis stage and IL28B genotype, and was not secondary to improved adherence to therapy or less pronounced anemia. Gene variants predicting reduced predicted ITPase activity also were associated with decreased risk of anemia (P<0.0001), increased risk of thrombocytopenia (P=0.007), and lower ribavirin concentrations (P=0.02). Conclusion: These findings demonstrate a novel ribavirin-like association between polymorphisms at ITPA and treatment efficacy in chronic hepatitis C mediated by reduced relapse risk. We hypothesize that patients (63%) being homozygous for both major alleles, leading to normal ITPase activity, may benefit more from the addition of ribavirin to present and future treatment regimens for HCV in spite of concomitant increased risk of anemia.
|
|
9. |
- Waldenström, Anders, et al.
(author)
-
Cardiomyocyte Microvesicles Contain DNA/RNA and Convey Biological Messages to Target Cells
- 2012
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:4, s. e34653-
-
Journal article (peer-reviewed)abstract
- Background: Shedding microvesicles are membrane released vesicles derived directly from the plasma membrane. Exosomes are released membrane vesicles of late endosomal origin that share structural and biochemical characteristics with prostasomes. Microvesicles/exosomes can mediate messages between cells and affect various cell-related processes in their target cells. We describe newly detected microvesicles/exosomes from cardiomyocytes and depict some of their biological functions.Methodology/Principal Findings: Microvesicles/exosomes from media of cultured cardiomyocytes derived from adult mouse heart were isolated by differential centrifugation including preparative ultracentrifugation and identified by transmission electron microscopy and flow cytometry. They were surrounded by a bilayered membrane and flow cytometry revealed presence of both caveolin-3 and flotillin-1 while clathrin and annexin-2 were not detected. Microvesicle/exosome mRNA was identified and out of 1520 detected mRNA, 423 could be directly connected in a biological network. Furthermore, by a specific technique involving TDT polymerase, 343 different chromosomal DNA sequences were identified in the microvesicles/exosomes. Microvesicle/exosomal DNA transfer was possible into target fibroblasts, where exosomes stained for DNA were seen in the fibroblast cytosol and even in the nuclei. The gene expression was affected in fibroblasts transfected by microvesicles/exosomes and among 333 gene expression changes there were 175 upregulations and 158 downregulations compared with controls.Conclusions/Significance: Our study suggests that microvesicles/exosomes released from cardiomyocytes, where we propose that exosomes derived from cardiomyocytes could be denoted "cardiosomes", can be involved in a metabolic course of events in target cells by facilitating an array of metabolism-related processes including gene expression changes.
|
|