20 results on '"Souren M"'
Search Results
2. Grey cast iron as cylinder-block material for range extender engines – A serious alternative?
- Author
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Souren, M., primary, Uhlmann, T., additional, and Slotman, J., additional
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- 2019
- Full Text
- View/download PDF
3. Werknemers met fysiek ongemakkelijk werk doorgaans minder tevreden
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Souren, M. and Bossche, S. van den
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Organisation ,WH - Work & Health ,Healthy for Life ,Workplace ,Healthy Living ,BSS - Behavioural and Societal Sciences - Published
- 2011
4. Surgical Trauma in Mice Modifies the Content of Circulating Extracellular Vesicles
- Author
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Souren Mkrtchian, Anette Ebberyd, Rosanne E. Veerman, María Méndez-Lago, Susanne Gabrielsson, Lars I. Eriksson, and Marta Gómez-Galán
- Subjects
circulating extracellular vesicles ,surgery ,proteomics ,miRNA ,alpha-synuclein ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Surgical interventions rapidly trigger a cascade of molecular, cellular, and neural signaling responses that ultimately reach remote organs, including the brain. Using a mouse model of orthopedic surgery, we have previously demonstrated hippocampal metabolic, structural, and functional changes associated with cognitive impairment. However, the nature of the underlying signals responsible for such periphery-to-brain communication remains hitherto elusive. Here we present the first exploratory study that tests the hypothesis of extracellular vesicles (EVs) as potential mediators carrying information from the injured tissue to the distal organs including the brain. The primary goal was to investigate whether the cargo of circulating EVs after surgery can undergo quantitative changes that could potentially trigger phenotypic modifications in the target tissues. EVs were isolated from the serum of the mice subjected to a tibia surgery after 6, 24, and 72 h, and the proteome and miRNAome were investigated using mass spectrometry and RNA-seq approaches. We found substantial differential expression of proteins and miRNAs starting at 6 h post-surgery and peaking at 24 h. Interestingly, one of the up-regulated proteins at 24 h was α-synuclein, a pathogenic hallmark of certain neurodegenerative syndromes. Analysis of miRNA target mRNA and corresponding biological pathways indicate the potential of post-surgery EVs to modify the extracellular matrix of the recipient cells and regulate metabolic processes including fatty acid metabolism. We conclude that surgery alters the cargo of circulating EVs in the blood, and our results suggest EVs as potential systemic signal carriers mediating remote effects of surgery on the brain.
- Published
- 2022
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5. Integrating rare genetic variants into pharmacogenetic drug response predictions
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Magnus Ingelman-Sundberg, Souren Mkrtchian, Yitian Zhou, and Volker M. Lauschke
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Pharmacogenetics ,Personalized medicine ,ADME genes ,Genetic variability ,Drug response ,Medicine ,Genetics ,QH426-470 - Abstract
Abstract Background Variability in genes implicated in drug pharmacokinetics or drug response can modulate treatment efficacy or predispose to adverse drug reactions. Besides common genetic polymorphisms, recent sequencing projects revealed a plethora of rare genetic variants in genes encoding proteins involved in drug metabolism, transport, and response. Results To understand the global importance of rare pharmacogenetic gene variants, we mapped the variability in 208 pharmacogenes by analyzing exome sequencing data from 60,706 unrelated individuals and estimated the importance of rare and common genetic variants using a computational prediction framework optimized for pharmacogenetic assessments. Our analyses reveal that rare pharmacogenetic variants were strongly enriched in mutations predicted to cause functional alterations. For more than half of the pharmacogenes, rare variants account for the entire genetic variability. Each individual harbored on average a total of 40.6 putatively functional variants, rare variants accounting for 10.8% of these. Overall, the contribution of rare variants was found to be highly gene- and drug-specific. Using warfarin, simvastatin, voriconazole, olanzapine, and irinotecan as examples, we conclude that rare genetic variants likely account for a substantial part of the unexplained inter-individual differences in drug metabolism phenotypes. Conclusions Combined, our data reveal high gene and drug specificity in the contributions of rare variants. We provide a proof-of-concept on how this information can be utilized to pinpoint genes for which sequencing-based genotyping can add important information to predict drug response, which provides useful information for the design of clinical trials in drug development and the personalization of pharmacological treatment.
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- 2018
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6. A study on knowledge, attitude, and practice regarding mental health illnesses in Amdanga block, West Bengal
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Rivu Basu, Arkaprabha Sau, Soham Saha, Souren Mondal, Pradip Kumar Ghoshal, and Sourav Kundu
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Attitude toward mental illness ,Community Attitudes to Mentally Illness ,structural equation model ,Public aspects of medicine ,RA1-1270 - Abstract
Background: The discourse of mental health is getting its due attention after all these years in India. A major threat to the mental health system is the demand side factors, namely, knowledge, attitude, and practice (KAP) of the general population toward this. In spite of growing concern regarding mental health in India, this kind of study to assess the mental health status has been very few in India, more so in West Bengal. Objectives: With this background, this study was carried out with the objectives to validate the Community Attitude to Mental Illness (CAMI), to assess the different sociodemographic factors among the study population, to assess the KAP regarding mental illness among the study population. Methods: It was an observational, descriptive study with cross-sectional design done at Amdanga Community Development Block, North 24 Parganas, West Bengal, India, in 2015-16. Questionnaire validation to assess the KAP was the primary objective with obtaining the descriptive data were the second one. CAMI questionnaire was used which was validated for the given area by validation methods such as Cronbach's alpha and structural equation modeling. The resultant questionnaire was used in the field on adult population after a single-stage survey design to collect 730 samples. Results: The test statistics showed that the questionnaire was reasonably valid after a few tweakings. SEM identified well-define domains in the attitude part. 94.9% says that they are willing to live with a people with mental illness. 14.9% has actually done so. Health-care seeking behavior shows that 19.2% will go to a GP in case of any mental illness. Furthermore, attitude toward mental illness showed mixed picture as also knowledge. This study correlated with various studies of developing countries and it was seen that these population showed markedly different attitudes for probability of the patients getting cured than many other countries. Furthermore, stigma was gradually decreasing, as evident from various other studies. Conclusion: This study will provide valuable insights into the cognitive and affective aspect of mental illness among these population and thus help in implementing better policies in this regard, as this is fast becoming the talk of the day.
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- 2017
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7. Computational Methods for the Pharmacogenetic Interpretation of Next Generation Sequencing Data
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Yitian Zhou, Kohei Fujikura, Souren Mkrtchian, and Volker M. Lauschke
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precision medicine ,personalized medicine ,variant effect prediction ,ADME ,NGS ,rare variant analysis ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Up to half of all patients do not respond to pharmacological treatment as intended. A substantial fraction of these inter-individual differences is due to heritable factors and a growing number of associations between genetic variations and drug response phenotypes have been identified. Importantly, the rapid progress in Next Generation Sequencing technologies in recent years unveiled the true complexity of the genetic landscape in pharmacogenes with tens of thousands of rare genetic variants. As each individual was found to harbor numerous such rare variants they are anticipated to be important contributors to the genetically encoded inter-individual variability in drug effects. The fundamental challenge however is their functional interpretation due to the sheer scale of the problem that renders systematic experimental characterization of these variants currently unfeasible. Here, we review concepts and important progress in the development of computational prediction methods that allow to evaluate the effect of amino acid sequence alterations in drug metabolizing enzymes and transporters. In addition, we discuss recent advances in the interpretation of functional effects of non-coding variants, such as variations in splice sites, regulatory regions and miRNA binding sites. We anticipate that these methodologies will provide a useful toolkit to facilitate the integration of the vast extent of rare genetic variability into drug response predictions in a precision medicine framework.
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- 2018
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8. Calcium Signaling in Liver Injury and Regeneration
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Nuria Oliva-Vilarnau, Simona Hankeova, Sabine U. Vorrink, Souren Mkrtchian, Emma R. Andersson, and Volker M. Lauschke
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metabolic disease ,non-alcoholic fatty liver disease ,ischemic-reperfusion injury ,hepatic cholestasis ,chronic liver disease ,Medicine (General) ,R5-920 - Abstract
The liver fulfills central roles in metabolic control and detoxification and, as such, is continuously exposed to a plethora of insults. Importantly, the liver has a unique ability to regenerate and can completely recoup from most acute, non-iterative insults. However, multiple conditions, including viral hepatitis, non-alcoholic fatty liver disease (NAFLD), long-term alcohol abuse and chronic use of certain medications, can cause persistent injury in which the regenerative capacity eventually becomes dysfunctional, resulting in hepatic scaring and cirrhosis. Calcium is a versatile secondary messenger that regulates multiple hepatic functions, including lipid and carbohydrate metabolism, as well as bile secretion and choleresis. Accordingly, dysregulation of calcium signaling is a hallmark of both acute and chronic liver diseases. In addition, recent research implicates calcium transients as essential components of liver regeneration. In this review, we provide a comprehensive overview of the role of calcium signaling in liver health and disease and discuss the importance of calcium in the orchestration of the ensuing regenerative response. Furthermore, we highlight similarities and differences in spatiotemporal calcium regulation between liver insults of different etiologies. Finally, we discuss intracellular calcium control as an emerging therapeutic target for liver injury and summarize recent clinical findings of calcium modulation for the treatment of ischemic-reperfusion injury, cholestasis and NAFLD.
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- 2018
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9. Process optimization in Nd:YAG laser microdrilling of alumina–aluminium interpenetrating phase composite
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Ranjib Biswas, Arunanshu S. Kuar, and Souren Mitra
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Microdrilling ,Alumina–aluminium IPC ,ND:YAG laser ,Hole diameter ,Taper ,Response surface methodology (RSM) ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In laser beam micromachining process, the quality of the drilled hole is of great importance. The quality of the microdrilled hole mainly depends on appropriate selection of process parameters. Predefined diameter of hole with minimum taper is of today's demand. The composite used for microdrilling operation is alumina–aluminium (Al2O3–Al) interpenetrating phase composite (IPC), which is widely used in aircraft and space stations. Until date, no experimental study has been done to obtain microdrilled hole of desired diameter. In the present paper three hole qualities such as hole diameter at entry, at exit and hole taper have been optimized individually as well as simultaneously using a central composite design (CCD) based on response surface methodology (RSM) during pulsed Nd:YAG laser microdrilling operation on alumina–aluminium IPC sheet of 1.14 mm thickness. The analysis of variance (ANOVA) test has also been done to identify the process parameters that contributed the most to get desired hole quality.
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- 2015
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10. Expression and Function of mARC: Roles in Lipogenesis and Metabolic Activation of Ximelagatran.
- Author
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Etienne P A Neve, Harald Köfeler, Delilah F G Hendriks, Åsa Nordling, Vladimir Gogvadze, Souren Mkrtchian, Erik Näslund, and Magnus Ingelman-Sundberg
- Subjects
Medicine ,Science - Abstract
Recently two novel enzymes were identified in the outer mitochondrial membrane, mARC1 and mARC2. These molybdenum containing enzymes can reduce a variety of N-hydroxylated compounds, such as N-hydroxy-guanidines and sulfohydroxamic acids, as well as convert nitrite into nitric oxide (NO). However, their endogenous functions remain unknown. Here we demonstrate a specific developmental pattern of expression of these enzymes. mARC1, but not mARC2, was found to be expressed in fetal human liver, whereas both, in particular mARC2, are abundant in adult liver and also expressed in omental and subcutaneous fat. Caloric diet restriction of obese patients caused a decreased expression of mARC2 in liver, similar to that seen in the livers of starved rats. Knock down of mARC2 expression by siRNA in murine adipocytes had statistically significant effect on the level of diglycerides and on the fatty acid composition of some triglycerides, concomitantly a clear trend toward the reduced formation of most of triglyceride and phospholipid species was observed. The involvement of mARC2 in the metabolism of the hepatotoxic drug ximelagatran was evaluated in hepatocytes and adipocytes. Ximelagatran was shown to cause oxidative stress and knock down of mARC2 in adipocytes prevented ximelagatran induced inhibition of mitochondrial respiration. In conclusion, our data indicate that mARC1 and mARC2 have different developmental expression profiles, and that mARC2 is involved in lipogenesis, is regulated by nutritional status and responsible for activation of ximelagatran into a mitotoxic metabolite(s).
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- 2015
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11. Developmental regulation and induction of cytochrome P450 2W1, an enzyme expressed in colon tumors.
- Author
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Eva Choong, Jia Guo, Anna Persson, Susanne Virding, Inger Johansson, Souren Mkrtchian, and Magnus Ingelman-Sundberg
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Medicine ,Science - Abstract
Cytochrome P450 2W1 (CYP2W1) is expressed predominantly in colorectal and also in hepatic tumors, whereas the levels are insignificant in the corresponding normal human adult tissues. CYP2W1 has been proposed as an attractive target for colorectal cancer (CRC) therapy by exploiting its ability to activate duocarmycin prodrugs to cytotoxic metabolites. However, its endogenous function, regulation and developmental pattern of expression remain unexplored. Here we report the CYP2W1 developmental expression in the murine and human gastrointestinal tissues. The gene expression in the colon and small intestine commence at early stages of embryonic life and is completely silenced shortly after the birth. Immunohistochemical analysis of human fetal colon revealed that CYP2W1 expression is restricted to the crypt cells. The silencing of CYP2W1 after birth correlates with the increased methylation of CpG-rich regions in both murine and human CYP2W1 genes. Analysis of CYP2W1 expression in the colon adenocarcinoma cell line HCC2998 revealed that the gene expression can be induced by e.g. the antitumor agent imatinib, linoleic acid and its derivatives. The imatinib mediated induction of CYP2W1 suggests an adjuvant therapy to treatment with duocarmycins that thus would involve induction of tumor CYP2W1 levels followed by the CYP2W1 activated duocarmycin prodrugs. Taken together these data strongly support further exploration of CYP2W1 as a specific drug target in CRC.
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- 2015
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12. Combination of Direct DNA Sequencing with Degenerate Primer-Mediated PCR and 5′-/3′-RACE to Screen Novel cDNA Sequences
- Author
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Che Fang, Souren Mkrtchian, and Magnus Ingelman-Sundberg
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Biology (General) ,QH301-705.5 - Published
- 1997
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13. A trans-Regulatory Code for the Forebrain Expression of Six3.2 in the Medaka Fish
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Paola Bovolenta, Raquel Marco-Ferreres, Jochen Wittbrodt, Marcel Souren, Ivan Conte, Anna Manfredi, Beate Wittbrodt, Noemi Tabanera, Leonardo Beccari, Beccari, L., Marco-Ferreres, R., Tabanera, N., Manfredi, A., Souren, M., Wittbrodt, B., Conte, I., Wittbrodt, J., Bovolenta, P., Fundación Ramón Areces, Centro de Investigación Biomédica en Red Enfermedades Raras (España), Fundación ONCE, Comunidad de Madrid, and Ministerio de Economía y Competitividad (España)
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Fish Proteins ,brain ,In silico ,Gene regulatory network ,Oryzias ,Context (language use) ,Nerve Tissue Proteins ,HCNC ,Computational biology ,Biology ,Biochemistry ,Animals, Genetically Modified ,Prosencephalon ,Animals ,Gene Regulatory Networks ,Gene Regulation ,RNA, Messenger ,Eye Proteins ,Molecular Biology ,Transcription factor ,transcriptional enhancers ,transcription factor ,Body Patterning ,Oryzia ,Genetics ,Regulation of gene expression ,Homeodomain Proteins ,Gene Regulatory Network ,neurodevelopment ,Animal ,Eye Protein ,Gene Expression Regulation, Developmental ,Homeodomain Protein ,Cell Biology ,transcriptional enhancer ,nervous system ,Fish Protein ,TCF3 ,Nerve Tissue Protein ,Forebrain ,PAX6 ,sense organs ,gene regulation ,transcription regulation ,Transcription Factors - Abstract
A well integrated and hierarchically organized gene regulatory network is responsible for the progressive specification of the forebrain. The transcription factor Six3 is one of the central components of this network. As such, Six3 regulates several components of the network, but its upstream regulators are still poorly characterized. Here we have systematically identified such regulators, taking advantage of the detailed functional characterization of the regulatory region of the medaka fish Six3.2 ortholog and of a time/cost-effective trans-regulatory screening, which complemented and overcame the limitations of in silico prediction approaches. The candidates resulting from this search were validated with dose-response luciferase assays and expression pattern criteria. Reconfirmed candidates with a matching expression pattern were also tested with chromatin immunoprecipitation and functional studies. Our results confirm the previously proposed direct regulation of Pax6 and further demonstrate that Msx2 and Pbx1 are bona fide direct regulators of early Six3.2 distribution in distinct domains of the medaka fish forebrain. They also point to other transcription factors, including Tcf3, as additional regulators of different spatial-temporal domains of Six3.2 expression. The activity of these regulators is discussed in the context of the gene regulatory network proposed for the specification of the forebrain., Spanish Ministerio de Economía y Competitividad (MINECO) Grants BFU2010-16031 and BFU2013-43213-P, cofounded by FEDER Funds; Comunidad Autónoma de Madrid (CAM) Grant CELL-DD S2010/BMD-2315; Fundaluce; Fundación ONCE; the Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) del Instituto Carlos III (ISCIII); and an Institutional Grant from the Fundación Ramón Areces.
- Published
- 2015
14. Estimating monthly labour force figures during the COVID-19 pandemic in the Netherlands.
- Author
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van den Brakel J, Souren M, and Krieg S
- Abstract
Official monthly statistics about the Dutch labour force are based on the Dutch Labour Force Survey (LFS). The LFS is a continuously conducted survey that is designed as a rotating panel design. Data collection among selected households is based on a mixed-mode design that uses web interviewing, telephone interviewing and face-to-face interviewing. Monthly estimates about the labour force are obtained with a structural time series model. Due to the COVID-19 pandemic, face-to-face interviewing stopped. It was anticipated that this would have a systematic effect on the outcomes of the LFS and that the lockdown at the same time affected the real monthly labour force figures. The lockdown indeed marked a sharp turning point in the evolution of the series of the monthly labour force figures and strongly increased the volatility of these series. In this paper, it is explained how Statistics Netherlands produced monthly labour force figures during the COVID-19 pandemic. It is shown how the sudden change in the mode effects, because face-to-face interviewing stopped, were separated from real period-to-period changes in the labour force figures. It is also explained how the time series model is adapted to the increased volatility in the labour force figures., (© 2022 The Authors. Journal of the Royal Statistical Society: Series A (Statistics in Society) published by John Wiley & Sons Ltd on behalf of Royal Statistical Society.)
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- 2022
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15. A trans-Regulatory Code for the Forebrain Expression of Six3.2 in the Medaka Fish.
- Author
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Beccari L, Marco-Ferreres R, Tabanera N, Manfredi A, Souren M, Wittbrodt B, Conte I, Wittbrodt J, and Bovolenta P
- Subjects
- Animals, Animals, Genetically Modified, Body Patterning genetics, Gene Expression Regulation, Developmental, Gene Regulatory Networks, Oryzias metabolism, RNA, Messenger genetics, RNA, Messenger metabolism, Transcription Factors genetics, Homeobox Protein SIX3, Eye Proteins genetics, Fish Proteins genetics, Homeodomain Proteins genetics, Nerve Tissue Proteins genetics, Oryzias embryology, Oryzias genetics, Prosencephalon embryology, Prosencephalon metabolism
- Abstract
A well integrated and hierarchically organized gene regulatory network is responsible for the progressive specification of the forebrain. The transcription factor Six3 is one of the central components of this network. As such, Six3 regulates several components of the network, but its upstream regulators are still poorly characterized. Here we have systematically identified such regulators, taking advantage of the detailed functional characterization of the regulatory region of the medaka fish Six3.2 ortholog and of a time/cost-effective trans-regulatory screening, which complemented and overcame the limitations of in silico prediction approaches. The candidates resulting from this search were validated with dose-response luciferase assays and expression pattern criteria. Reconfirmed candidates with a matching expression pattern were also tested with chromatin immunoprecipitation and functional studies. Our results confirm the previously proposed direct regulation of Pax6 and further demonstrate that Msx2 and Pbx1 are bona fide direct regulators of early Six3.2 distribution in distinct domains of the medaka fish forebrain. They also point to other transcription factors, including Tcf3, as additional regulators of different spatial-temporal domains of Six3.2 expression. The activity of these regulators is discussed in the context of the gene regulatory network proposed for the specification of the forebrain., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
- Full Text
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16. Integration of Hedgehog and BMP signalling by the engrailed2a gene in the zebrafish myotome.
- Author
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Maurya AK, Tan H, Souren M, Wang X, Wittbrodt J, and Ingham PW
- Subjects
- Animals, Base Sequence, Bone Morphogenetic Proteins metabolism, Cell Line, Cricetinae, Enhancer Elements, Genetic, Gene Expression Regulation, Developmental, Hedgehog Proteins metabolism, Homeodomain Proteins metabolism, Molecular Sequence Data, Nerve Tissue Proteins metabolism, Protein Binding, Smad5 Protein genetics, Smad5 Protein metabolism, Transcription Factors metabolism, Transcription, Genetic, Zebrafish genetics, Zebrafish Proteins metabolism, Zinc Finger Protein Gli2, Homeodomain Proteins genetics, Muscle, Skeletal embryology, Muscle, Skeletal metabolism, Nerve Tissue Proteins genetics, Signal Transduction, Zebrafish embryology, Zebrafish metabolism, Zebrafish Proteins genetics
- Abstract
Different levels and timing of Hedgehog (Hh) signalling activity have been proposed to specify three distinct cell types in the zebrafish myotome. Two of these, the medial fast-twitch fibres (MFFs) and the slow-twitch muscle pioneers (MPs) are characterised by expression of eng1a, -1b and -2a and require the highest levels of Hh for their specification. We have defined a minimal eng2a element sufficient to drive reporter expression specifically in MPs and MFFs. This element binds both Gli2a, a mediator of Hh signalling, and activated Smads (pSmads), mediators of bone morphogenic protein (BMP) signalling, in vivo. We found a strict negative correlation between nuclear accumulation of pSmad, and eng2a expression in myotomal cells and show that abrogation of pSmad accumulation results in activation of eng2a, even when Hh signalling is attenuated. Conversely, driving nuclear accumulation of pSmad suppresses the induction of eng expression even when Hh pathway activity is maximal. Nuclear accumulation of pSmads is depleted by maximal Hh pathway activation. We show that a synthetic form of the Gli2 repressor interacts with Smad1 specifically in the nuclei of myotomal cells in the developing embryo and that this interaction depends upon BMP signalling activity. Our results demonstrate that the eng2a promoter integrates repressive and activating signals from the BMP and Hh pathways, respectively, to limit its expression to MPs and MFFs. We suggest a novel basis for crosstalk between the Hh and BMP pathways, whereby BMP-mediated repression of Hh target genes is promoted by a direct interaction between Smads and truncated Glis, an interaction that is abrogated by Hh induced depletion of the latter.
- Published
- 2011
- Full Text
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17. A global survey identifies novel upstream components of the Ath5 neurogenic network.
- Author
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Souren M, Martinez-Morales JR, Makri P, Wittbrodt B, and Wittbrodt J
- Subjects
- Animals, Basic Helix-Loop-Helix Transcription Factors metabolism, Cell Line, Eye cytology, Eye innervation, Eye metabolism, Eye Proteins genetics, Eye Proteins metabolism, Fish Proteins metabolism, Gene Regulatory Networks, In Situ Hybridization, Fluorescence, Luciferases genetics, Luciferases metabolism, Microscopy, Confocal, Nerve Tissue Proteins genetics, Nerve Tissue Proteins metabolism, Oryzias embryology, Oryzias genetics, Oryzias growth & development, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Retinal Ganglion Cells cytology, Time Factors, Transfection, Basic Helix-Loop-Helix Transcription Factors genetics, Fish Proteins genetics, Gene Expression Profiling, Gene Expression Regulation, Developmental, Retinal Ganglion Cells metabolism
- Abstract
Background: Investigating the architecture of gene regulatory networks (GRNs) is essential to decipher the logic of developmental programs during embryogenesis. In this study we present an upstream survey approach, termed trans-regulation screen, to comprehensively identify the regulatory input converging on endogenous regulatory sequences., Results: Our dual luciferase-based screen queries transcriptome-scale collections of cDNAs. Using this approach we study the regulation of Ath5, the central node in the GRN controlling retinal ganglion cell (RGC) specification in vertebrates. The Ath5 promoter integrates the input of upstream regulators to enable the transient activation of the gene, which is an essential step for RGC differentiation. We efficiently identified potential Ath5 regulators that were further filtered for true positives by an in situ hybridization screen. Their regulatory activity was validated in vivo by functional assays in medakafish embryos., Conclusions: Our analysis establishes functional groups of genes controlling different regulatory phases, including the onset of Ath5 expression at cell-cycle exit and its down-regulation prior to terminal RGC differentiation. These results extent the current model of the GRN controlling retinal neurogenesis in vertebrates.
- Published
- 2009
- Full Text
- View/download PDF
18. Early development of functional spatial maps in the zebrafish olfactory bulb.
- Author
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Li J, Mack JA, Souren M, Yaksi E, Higashijima S, Mione M, Fetcho JR, and Friedrich RW
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- Animals, Animals, Genetically Modified, Green Fluorescent Proteins analysis, Green Fluorescent Proteins genetics, Odorants, Olfactory Bulb growth & development, Smell, Zebrafish, Olfactory Bulb anatomy & histology, Olfactory Bulb physiology
- Abstract
In the adult olfactory bulb (OB), particular chemical classes of odorants preferentially activate glomeruli within loosely defined regions, resulting in a coarse and fractured "chemotopic" map. In zebrafish, amino acids and bile acids predominantly stimulate glomeruli in the lateral and medial OB, respectively. We studied the development of these spatial response maps in zebrafish. At 3 d postfertilization (dpf), the OB contained protoglomerular structures that became refined and more numerous during subsequent days. In a transgenic zebrafish line expressing the Ca2+ indicator protein inverse pericam, mainly in mitral cells, odor responses in the OB were first detected at 2.5-3 dpf. Already at this stage, amino acids and bile acids evoked activity predominantly in the lateral and medial OB, respectively. Two-photon Ca2+ imaging using a synthetic indicator was used to reconstruct activity patterns at higher resolution in three dimensions. Responses to amino acids and bile acids were detected predominantly in the lateral and medial OB, respectively, with little overlap. Between 2.5 and 6 dpf, the number of odor-responsive units increased, but the overall spatial organization of activity persisted. Hence, a coarse spatial organization of functional activity maps is established very early during OB development when glomeruli are not yet differentiated. This spatial organization is maintained during development and growth of neuronal circuits and may have important functions for odor processing in larvae, for the differentiation of glomeruli, and for the refinement of activity maps at later developmental stages.
- Published
- 2005
- Full Text
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19. The discovery, positioning and verification of a set of transcription-associated motifs in vertebrates.
- Author
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Ettwiller L, Paten B, Souren M, Loosli F, Wittbrodt J, and Birney E
- Subjects
- Animals, Conserved Sequence, Embryo, Nonmammalian cytology, Evolution, Molecular, Humans, Promoter Regions, Genetic genetics, Reproducibility of Results, SELEX Aptamer Technique, Sequence Deletion genetics, Takifugu genetics, Transgenes, Regulatory Sequences, Nucleic Acid genetics, Transcription, Genetic genetics, Vertebrates genetics
- Abstract
We have developed several new methods to investigate transcriptional motifs in vertebrates. We developed a specific alignment tool appropriate for regions involved in transcription control, and exhaustively enumerated all possible 12-mers for involvement in transcription by virtue of their mammalian conservation. We then used deeper comparative analysis across vertebrates to identify the active instances of these motifs. We have shown experimentally in Medaka fish that a subset of these predictions is involved in transcription.
- Published
- 2005
- Full Text
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20. The onset of action of formoterol, a new beta 2 adrenoceptor agonist.
- Author
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Stam J, Souren M, and Zweers P
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- Adult, Aged, Airway Obstruction physiopathology, Double-Blind Method, Female, Forced Expiratory Volume, Formoterol Fumarate, Humans, Male, Middle Aged, Time Factors, Adrenergic beta-Agonists therapeutic use, Airway Obstruction drug therapy, Bronchodilator Agents therapeutic use, Ethanolamines therapeutic use
- Abstract
Formoterol, a new long-acting beta 2-agonist, seems to be a step forward in the treatment of recurrent obstructive airway disease. Obstruction during the night and morning dip are less frequent and patient compliance is expected to be better than with the bronchodilators now in use. We studied the characteristics of the onset of action of formoterol by measuring sGAW (sGAW = specific airway conductance) to see if formoterol could be used as a rescue drug in cases of sudden attacks of obstruction. Our results show that one minute after inhalation of 12 micrograms formoterol MDI 14 patients out of 20 have a clinically relevant increase in sGAW after formoterol (+ 40% of the initial values) in comparison with 2 patients receiving placebo.
- Published
- 1993
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