70 results on '"Chakroun I"'
Search Results
2. Towards a heterogeneous and adaptive parallel Branch-and-Bound algorithm
- Author
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Chakroun, I. and Melab, N.
- Published
- 2015
- Full Text
- View/download PDF
3. Operator-level GPU-Accelerated Branch and Bound Algorithms
- Author
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Chakroun, I. and Melab, N.
- Published
- 2013
- Full Text
- View/download PDF
4. Évolution de la rétinopathie diabétique après chirurgie de la cataracte par phacoémulsification
- Author
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Chéour, M., Mazlout, H., Falfoul, Y., Chakroun, I., Marrakchi, A., Skhiri, M., Zarrad, A., and Kraïem, A.
- Published
- 2013
- Full Text
- View/download PDF
5. IL-1 activates two phospholipid signaling pathways in intestinal epithelial cells
- Author
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Homaidan, F. R., Chakroun, I., Dbaibo, G. S., El-Assaad, W., and El-Sabban, M. E.
- Published
- 2001
- Full Text
- View/download PDF
6. 5PSQ-156 Risk assessment and management to improve thermo-sensitive drugs safety
- Author
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Sakly, H, primary, Chakroun, I, additional, and Ben Jeddou, K, additional
- Published
- 2019
- Full Text
- View/download PDF
7. Neuropathie optique compressive secondaire à un macroadénome hypophysaire
- Author
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Cheour, M., Mazlout, H., Agrebi, S., Falfoul, Y., Chakroun, I., Lajmi, H., and Kraiem, A.
- Published
- 2013
- Full Text
- View/download PDF
8. Interactions between candidate probiotics and the immune and antioxidative responses of European sea bass (Dicentrarchus labrax) larvae
- Author
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Lamari, F, primary, Mahdhi, A, additional, Chakroun, I, additional, Esteban, M A, additional, Mazurais, D, additional, Amina, B, additional, and Gatesoupe, F-J, additional
- Published
- 2016
- Full Text
- View/download PDF
9. Combining multi-core and GPU computing for solving combinatorial optimization problems
- Author
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Chakroun, I., primary, Melab, N., additional, Mezmaz, M., additional, and Tuyttens, D., additional
- Published
- 2013
- Full Text
- View/download PDF
10. Graphics processing unit-accelerated bounding for branch-and-bound applied to a permutation problem using data access optimization
- Author
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Melab, N., primary, Chakroun, I., additional, and Bendjoudi, A., additional
- Published
- 2013
- Full Text
- View/download PDF
11. Reducing thread divergence in a GPU‐accelerated branch‐and‐bound algorithm
- Author
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Chakroun, I., primary, Mezmaz, M., additional, Melab, N., additional, and Bendjoudi, A., additional
- Published
- 2012
- Full Text
- View/download PDF
12. A GPU-accelerated Branch-and-Bound Algorithm for the Flow-Shop Scheduling Problem
- Author
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Melab, N., primary, Chakroun, I., additional, Mezmaz, M., additional, and Tuyttens, D., additional
- Published
- 2012
- Full Text
- View/download PDF
13. An Adaptative Multi-GPU Based Branch-and-Bound. A Case Study: The Flow-Shop Scheduling Problem
- Author
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Chakroun, I., primary and Melab, N., additional
- Published
- 2012
- Full Text
- View/download PDF
14. Synthesis of novel phthalimido oxime pseudoesters and evaluation of their cytotoxicity
- Author
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Mehrez Asma, Chakroun Ibtissem, Mtat Dalila, Ben Mansour Hédi, and Touati Ridha
- Subjects
oxime esters ,α-amino acids ,stereoselective ,cytotoxic ,biological activity ,enantiomer ,Chemistry ,QD1-999 - Abstract
A series of novel optically pure oxime pseudoesters derivatives were synthesized by the reaction of substitute keto oximes with various N-substituted α-amino acids chlorides in the presence of triethylamine and dichloromethane at 0°C, and their structures were characterized by IR and 1D-NMR methods. The synthesized compounds were tested for their ability to inhibit the proliferation of human colon cancer cells and human epithelial cells. Some of them were revealed to have a significant cytotoxic effect.
- Published
- 2020
- Full Text
- View/download PDF
15. Graphics processing unit-accelerated bounding for branch-and-bound applied to a permutation problem using data access optimization.
- Author
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Melab, N., Chakroun, I., and Bendjoudi, A.
- Subjects
BRANCH & bound algorithms ,GRAPHICS processing units ,MATHEMATICAL optimization ,FLOW shop scheduling ,COMPUTER software execution ,CENTRAL processing units ,PERMUTATIONS - Abstract
SUMMARY Branch-and-bound (B&B) algorithms are attractive methods for solving to optimality combinatorial optimization problems using an implicit enumeration of a dynamically built tree-based search space. Nevertheless, they are time-consuming when dealing with large problem instances. Therefore, pruning tree nodes (subproblems) is traditionally used as a powerful mechanism to reduce the size of the explored search space. Pruning requires to perform the bounding operation, which consists of applying a lower bound function to the subproblems generated during the exploration process. Preliminary experiments performed on the Flow-Shop scheduling problem (FSP) have shown that the bounding operation consumes over 98 % of the execution time of the B&B algorithm. In this paper, we investigate the use of graphics processing unit (GPU) computing as a major complementary way to speed up the search. We revisit the design and implementation of the parallel bounding model on GPU accelerators. The proposed approach enables data access optimization. Extensive experiments have been carried out on well-known FSP benchmarks using an Nvidia Tesla C2050 GPU card. Compared to a CPU-based single core execution using an Intel Core i7-970 processor without GPU, speedups higher than 100 times faster are achieved for large problem instances. At an equivalent peak performance, GPU-accelerated B&B is twice faster than its multi-core counterpart. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
16. IL-1 increases ceramide production and induces COX-2 in intestinal epithelial cells
- Author
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Homaidan, F.R., primary, El-Assaad, W., additional, Chakroun, I., additional, Dbaibo, G., additional, and El-Sabban, M.E., additional
- Published
- 1998
- Full Text
- View/download PDF
17. Reducing thread divergence in a GPU-accelerated branch-and-bound algorithm.
- Author
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Chakroun, I., Mezmaz, M., Melab, N., and Bendjoudi, A.
- Subjects
GRAPHICS processing units ,ALGORITHMS ,PROBLEM solving ,COMBINATORIAL optimization ,COMPUTER scheduling ,DATA analysis - Abstract
SUMMARY In this paper, we address the design and implementation of graphical processing unit (GPU)-accelerated branch-and-bound algorithms (B&B) for solving flow-shop scheduling optimization problems (FSP). Such applications are CPU-time consuming and highly irregular. On the other hand, GPUs are massively multithreaded accelerators using the single instruction multiple data model at execution. A major issue that arises when executing on GPU, a B&B applied to FSP is thread or branch divergence. Such divergence is caused by the lower bound function of FSP that contains many irregular loops and conditional instructions. Our challenge is therefore to revisit the design and implementation of B&B applied to FSP dealing with thread divergence. Extensive experiments of the proposed approach have been carried out on well-known FSP benchmarks using an Nvidia Tesla (C2050 GPU card (http://www.nvidia.com/docs/IO/43395/NV_DS_Tesla_C2050_C2070_jul10_lores.pdf)). Compared with a CPU-based execution, accelerations up to × 77.46 are achieved for large problem instances. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
18. Chemical and physical characterization of some tunisian smectites for human healing use
- Author
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Emna Fakhfakh, Chakroun, I., Chaari, I., Medhioub, M., Rocha, F., Gomes, C., Lopez-Galindo, A., Kooli, F., Zargouni, F., and Jamoussi, F.
19. Analysis of the Six4 cistrome in mouse C2C12 skeletal muscle myoblasts
- Author
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Chakroun, I, primary
- Full Text
- View/download PDF
20. Dietary administration effects of exopolysaccharide from potential probiotic strains on immune and antioxidant status and nutritional value of European sea bass (Dicentrarchus labrax L.)
- Author
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Concetta Maria Messina, Andrea Santulli, Hatem Majdoub, Ridha El Mzoughi, María Ángeles Esteban, Rosaria Arena, Abdelkarim Mahdhi, Cristóbal Espinosa-Ruíz, Ibtissem Chakroun, Mahdhi A., Chakroun I., Espinosa-Ruiz C., Messina C.M., Arena R., Majdoub H., Santulli A., Mzoughi R., and Esteban M.A.
- Subjects
Antioxidant ,040301 veterinary sciences ,medicine.medical_treatment ,Aquaculture ,Antioxidants ,law.invention ,0403 veterinary science ,European sea ba ,03 medical and health sciences ,Probiotic ,Immune system ,law ,Exopolysaccharide ,Settore AGR/20 - Zoocolture ,medicine ,Animals ,Food science ,Sea bass ,Settore BIO/06 - Anatomia Comparata E Citologia ,030304 developmental biology ,chemistry.chemical_classification ,Innate immunity ,0303 health sciences ,General Veterinary ,biology ,Probiotics ,Fatty Acids ,Polysaccharides, Bacterial ,Fatty acid ,04 agricultural and veterinary sciences ,biology.organism_classification ,Animal Feed ,Eicosapentaenoic acid ,Diet ,chemistry ,Docosahexaenoic acid ,Animal Nutritional Physiological Phenomena ,Bass ,Dicentrarchus ,Gene expression ,Nutritive Value - Abstract
The use of biological immunostimulants is considered a valuable practice to improve culture conditions in aquaculture sector that may help to increase production and maintain healthy environment. We undertook this study in order to evaluate the potential effect of the administration of two exopolysaccharides (EPS) "EPLB" and "EPB" derived from potential probiotic strains on immune and antioxidant status of European sea bass (Dicentrarchus labrax L.) larvae. In order to find out if the EPSs have an effect on the biochemical composition during the trial period, the nutritional value has been evaluated. The results revealed that expression levels of immune-relevant genes (infg, Il1b, Il8, Il6 and tcr-β) in the gut and head kidney and the scavenging enzymes (cat, sod, gr) genes in the liver were modulated. In fact, the dietary supplementation with the tested EPSs, significantly enhances the expression of immune-associated genes in the head-kidney, particularly infg and tcrβ, as well as catalase gene in liver. During the period of study, EPSs administration did not affect the fatty acid profiles of larvae, which is balanced. This is confirmed by the Docosahexaenoic acid / Eicosapentaenoic acid ratio and demonstrates that EPLB and EPB can be administrated without any negative effect on biochemical composition of European sea bass. The present findings provided evidence that the tested EPSs with antibacterial and antioxidant activities can enhance immune response without negative effect on the biochemical composition. The used EPSs can be considered as a good source of natural functional aquafeed ingredients for European sea bass.
- Published
- 2020
21. The integrated stress response promotes neural stem cell survival under conditions of mitochondrial dysfunction in neurodegeneration.
- Author
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Iqbal MA, Bilen M, Liu Y, Jabre V, Fong BC, Chakroun I, Paul S, Chen J, Wade S, Kanaan M, Harper ME, Khacho M, and Slack RS
- Subjects
- Animals, Mice, Neurodegenerative Diseases metabolism, Neurodegenerative Diseases pathology, Neurodegenerative Diseases genetics, Activating Transcription Factor 4 metabolism, Activating Transcription Factor 4 genetics, Stress, Physiological, Oxidative Stress, Neural Stem Cells metabolism, Mitochondria metabolism, Cell Survival
- Abstract
Impaired mitochondrial function is a hallmark of aging and a major contributor to neurodegenerative diseases. We have shown that disrupted mitochondrial dynamics typically found in aging alters the fate of neural stem cells (NSCs) leading to impairments in learning and memory. At present, little is known regarding the mechanisms by which neural stem and progenitor cells survive and adapt to mitochondrial dysfunction. Using Opa1-inducible knockout as a model of aging and neurodegeneration, we identify a decline in neurogenesis due to impaired stem cell activation and progenitor proliferation, which can be rescued by the mitigation of oxidative stress through hypoxia. Through sc-RNA-seq, we identify the ATF4 pathway as a critical mechanism underlying cellular adaptation to metabolic stress. ATF4 knockdown in Opa1-deficient NSCs accelerates cell death, while the increased expression of ATF4 enhances proliferation and survival. Using a Slc7a11 mutant, an ATF4 target, we show that ATF4-mediated glutathione production plays a critical role in maintaining NSC survival and function under stress conditions. Together, we show that the activation of the integrated stress response (ISR) pathway enables NSCs to adapt to metabolic stress due to mitochondrial dysfunction and metabolic stress and may serve as a therapeutic target to enhance NSC survival and function in aging and neurodegeneration., (© 2024 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.)
- Published
- 2024
- Full Text
- View/download PDF
22. Identifying and evaluating barriers for the implementation of machine learning in the intensive care unit.
- Author
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D'Hondt E, Ashby TJ, Chakroun I, Koninckx T, and Wuyts R
- Abstract
Background: Despite apparent promise and the availability of numerous examples in the literature, machine learning models are rarely used in practice in ICU units. This mismatch suggests that there are poorly understood barriers preventing uptake, which we aim to identify., Methods: We begin with a qualitative study with 29 interviews of 40 Intensive Care Unit-, hospital- and MedTech company staff members. As a follow-up to the study, we attempt to quantify some of the technical issues raised. To perform experiments we selected two models based on criteria such as medical relevance. Using these models we measure the loss of performance in predictive models due to drift over time, change of available patient features, scarceness of data, and deploying a model in a different context to the one it was built in., Results: The qualitative study confirms our assumptions on the potential of AI-driven analytics for patient care, as well as showing the prevalence and type of technical blocking factors that are responsible for its slow uptake. The experiments confirm that each of these issues can cause important loss of predictive model performance, depending on the model and the issue., Conclusions: Based on the qualitative study and quantitative experiments we conclude that more research on practical solutions to enable AI-driven innovation in Intensive Care Units is needed. Furthermore, the general poor situation with respect to public, usable implementations of predictive models would appear to limit the possibilities for both the scientific repeatability of the underlying research and the transfer of this research into practice., (© 2022. The Author(s).)
- Published
- 2022
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- View/download PDF
23. The Rb/E2F axis is a key regulator of the molecular signatures instructing the quiescent and activated adult neural stem cell state.
- Author
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Fong BC, Chakroun I, Iqbal MA, Paul S, Bastasic J, O'Neil D, Yakubovich E, Bejjani AT, Ahmadi N, Carter A, Clark A, Leone G, Park DS, Ghanem N, Vandenbosch R, and Slack RS
- Subjects
- Neurogenesis physiology, Cell Division, Cell Cycle, Retinoblastoma Protein genetics, Retinoblastoma Protein metabolism, Neural Stem Cells metabolism, Adult Stem Cells metabolism
- Abstract
Long-term maintenance of the adult neurogenic niche depends on proper regulation of entry and exit from quiescence. Neural stem cell (NSC) transition from quiescence to activation is a complex process requiring precise cell-cycle control coordinated with transcriptional and morphological changes. How NSC fate transitions in coordination with the cell-cycle machinery remains poorly understood. Here we show that the Rb/E2F axis functions by linking the cell-cycle machinery to pivotal regulators of NSC fate. Deletion of Rb family proteins results in activation of NSCs, inducing a transcriptomic transition toward activation. Deletion of their target activator E2Fs1/3 results in intractable quiescence and cessation of neurogenesis. We show that the Rb/E2F axis mediates these fate transitions through regulation of factors essential for NSC function, including REST and ASCL1. Thus, the Rb/E2F axis is an important regulator of NSC fate, coordinating cell-cycle control with NSC activation and quiescence fate transitions., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
24. The Synbiotic Effect of Probiotics and Dried Spirulina platensis or Phycocyanin on Biofilm Formation by Salmonella Typhimurium and Staphylococcus aureus .
- Author
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Chakroun I, Fedhila K, Maatallah M, Mzoughi R, Bakhrouf A, and Krichen Y
- Subjects
- Humans, Phycocyanin pharmacology, Staphylococcus aureus, Salmonella typhimurium, Biofilms, Synbiotics, Probiotics pharmacology
- Abstract
This study aimed to evaluate the synbiotic effect of probiotics and dried Spirulina platensis or phycocyanin on autoaggregation, coaggregation, and the inhibition of biofilm formation by Salmonella Typhimurium and Staphylococcus aureus on 96-well microtiter plates and Human colon carcinoma cells-116 surfaces. The results showed that the probiotics strains cultured in the presence of S. platensis exhibited the highest autoaggregation values, ranging between 68.5 and 74.2% after 24 h. All probiotic strains with or without S. platensis and phycocyanin showed coaggregation abilities with S. Typhimurium and S. aureus . Interestingly, significant effect of S. platensis and phycocyanin supplementation was observed on the inhibition of the biofilm formation by the selected pathogens during the competition, exclusion, and displacement on abiotic and biotic surfaces.
- Published
- 2022
- Full Text
- View/download PDF
25. Application of Failure Mode, Effects, and Criticality Analysis to the Medication-Use Process for Temperature-Sensitive Drugs in a University Hospital.
- Author
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Sakly H, Chakroun I, and Ben Jeddou K
- Abstract
Background: In the hospital setting, the medication-use system for temperature-sensitive drugs is a high-risk process., Objectives: To analyze the risks associated with the hospital-based medication-use process and to propose corrective and preventive actions for the most critical failure modes., Methods: A multidisciplinary team was trained to analyze the medication-use process for temperature-sensitive drugs and to identify potential failures using a risk analysis method known as failure mode, effects, and criticality analysis (FMECA). The medication-use process, from initial supply to administration to patients, was investigated using "the 5 Ws and How" method (Who? What? Where? When? Why? How?), and the causes of the failure modes were analyzed using Ishikawa diagrams. The most critical failure modes were selected using the Pareto law, and relevant improvement actions were proposed., Results: This analysis identified 41 failure modes for the 9 stages of the medication-use process, of which only 36 were deemed assessable by the participants. Eighteen (50%) of these failure modes were critical, according to the Pareto law, with criticality indices between 12 and 60. The stage of tidying up and storage in patient care units had the highest number of critical failures ( n = 5). A total of 48 corrective actions were proposed., Conclusion: The proposed action plan prioritized 3 areas for improvement: the documentation system, staff training, and equipment acquisition. A second FMECA should be carried out to reassess the medication-use process after implementation of these improvement actions. The second FMECA, allowing detection of residual risks and identification of new risks, will be part of a continuous improvement process., Competing Interests: Competing interests: None declared., (2022 Canadian Society of Hospital Pharmacists. All content in the Canadian Journal of Hospital Pharmacy is copyrighted by the Canadian Society of Hospital Pharmacy. In submitting their manuscripts, the authors transfer, assign, and otherwise convey all copyright ownership to CSHP.)
- Published
- 2022
- Full Text
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26. Pathogenic Impacts of Bacillus cereus Strains on Crassostrea gigas .
- Author
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Haddaji N, Chakroun I, Fdhila K, Smati H, Bakhrouf A, and Mzoughi R
- Subjects
- Animals, Bacillus cereus, Flow Cytometry, Hemocytes, Crassostrea microbiology
- Abstract
Regarding the economic importance of bivalve farming, a great deal of interest has recently been devoted to studying the pathogenesis of infectious diseases of these mollusks to prepare for public health emergencies. Bacillus cereus is one of these pathogens; it is a ubiquitous soil bacterium responsible for many types of gastrointestinal diseases associated with food. This study was conducted to determine the pathogenic effect of B. cereus on Crassostrea gigas . This effect was studied by assessing hemocytes death using flow cytometry analysis. The results showed that only ∼15% of C. gigas were able to survive after B. cereus artificial infection with 10
8 CFU (colony-forming unit)/oyster. Evenly, the percentage of nonviable hemocytes gradually increased with the concentration of B. cereus , with a peak value of ∼40% after infection. Indeed, findings showed that this strain is harmful to C. gigas .- Published
- 2022
- Full Text
- View/download PDF
27. Six1 promotes skeletal muscle thyroid hormone response through regulation of the MCT10 transporter.
- Author
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Girgis J, Yang D, Chakroun I, Liu Y, and Blais A
- Subjects
- Animals, Gene Expression Regulation, Mice, Muscle, Skeletal metabolism, Thyroid Hormones, Transcription Factors genetics, Amino Acid Transport Systems, Neutral, Homeodomain Proteins genetics
- Abstract
Background: The Six1 transcription factor is implicated in controlling the development of several tissue types, notably skeletal muscle. Six1 also contributes to muscle metabolism and its activity is associated with the fast-twitch, glycolytic phenotype. Six1 regulates the expression of certain genes of the fast muscle program by directly stimulating their transcription or indirectly acting through a long non-coding RNA. We hypothesized that additional mechanisms of action of Six1 might be at play., Methods: A combined analysis of gene expression profiling and genome-wide location analysis data was performed. Results were validated using in vivo RNA interference loss-of-function assays followed by measurement of gene expression by RT-PCR and transcriptional reporter assays., Results: The Slc16a10 gene, encoding the thyroid hormone transmembrane transporter MCT10, was identified as a gene with a transcriptional enhancer directly bound by Six1 and requiring Six1 activity for full expression in adult mouse tibialis anterior, a predominantly fast-twitch muscle. Of the various thyroid hormone transporters, MCT10 mRNA was found to be the most abundant in skeletal muscle, and to have a stronger expression in fast-twitch compared to slow-twitch muscle groups. Loss-of-function of MCT10 in the tibialis anterior recapitulated the effect of Six1 on the expression of fast-twitch muscle genes and led to lower activity of a thyroid hormone receptor-dependent reporter gene., Conclusions: These results shed light on the molecular mechanisms controlling the tissue expression profile of MCT10 and identify modulation of the thyroid hormone signaling pathway as an additional mechanism by which Six1 influences skeletal muscle metabolism., (© 2021. The Author(s).)
- Published
- 2021
- Full Text
- View/download PDF
28. Atypical Salmonella Typhimurium persistence in the pacific oyster, Crassostrea gigas, and its effect on the variation of gene expression involved in the oyster's immune system.
- Author
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Chakroun I, Fedhila K, Mahdhi A, Mzoughi R, Saidane D, Esteban MÁ, and Bakhrouf A
- Subjects
- Animals, Gene Expression, Immune System, Salmonella typhimurium genetics, Crassostrea, Vibrio genetics
- Abstract
Salmonella is one of the most important pathogens involved in food intoxication outbreaks, and in many cases, the intoxication has been linked to shellfish which is typically consumed raw. While much is understood about the interactions between Salmonella and vertebrates, much less is known about its relationships with invertebrates, which could be an overlooked and important aspect to better understand the Salmonella interaction with its diversified hosts. The aim of this study was to investigate the effect of preadaptation in seawater microcosms during 12 months on Salmonella Typhimurium by determining its survival capacity within this mollusk over a period of 30 days. The results showed that the stressed bacteria are able to survive in this mollusk at a higher concentration even after thirty days of infection compared to bacteria in the normal state. In order to minimize the effect of an experimental device for one month on the survival of Salmonella, we carried out an in vitro study to determine the number of viable Salmonella in the hemocytes of oysters. Interestingly, we evaluated the effect of the antibacterial activity of different extracts of C. gigas using the solvents (Methanol, Ethanol and acetic acid) specifically against stressed and unstressed Salmonella. Furthermore, we compared the expression of three genes in the oyster Cg-big-def1, timp and sod in response to experimental infections of this mollusk with Vibrio splendidus kb133 and S. Typhimurium LT2DT104 in normal and stressed states. These findings are very important to contribute to explaining several questions about the persistence of S. Typhimurium for a long time in C. gigas and the host's immune response to this microorganism which is considered to be non-virulent for molluscs., (Copyright © 2021 Elsevier Ltd. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
29. Dietary administration effects of exopolysaccharide from potential probiotic strains on immune and antioxidant status and nutritional value of European sea bass (Dicentrarchus labrax L.).
- Author
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Mahdhi A, Chakroun I, Espinosa-Ruiz C, Messina CM, Arena R, Majdoub H, Santulli A, Mzoughi R, and Esteban MA
- Subjects
- Animal Feed analysis, Animal Nutritional Physiological Phenomena, Animals, Antioxidants metabolism, Aquaculture, Diet veterinary, Fatty Acids metabolism, Nutritive Value, Bass, Polysaccharides, Bacterial pharmacology, Probiotics
- Abstract
The use of biological immunostimulants is considered a valuable practice to improve culture conditions in aquaculture sector that may help to increase production and maintain healthy environment. We undertook this study in order to evaluate the potential effect of the administration of two exopolysaccharides (EPS) "EPLB" and "EPB" derived from potential probiotic strains on immune and antioxidant status of European sea bass (Dicentrarchus labrax L.) larvae. In order to find out if the EPSs have an effect on the biochemical composition during the trial period, the nutritional value has been evaluated. The results revealed that expression levels of immune-relevant genes (infg, Il1b, Il8, Il6 and tcr-β) in the gut and head kidney and the scavenging enzymes (cat, sod, gr) genes in the liver were modulated. In fact, the dietary supplementation with the tested EPSs, significantly enhances the expression of immune-associated genes in the head-kidney, particularly infg and tcrβ, as well as catalase gene in liver. During the period of study, EPSs administration did not affect the fatty acid profiles of larvae, which is balanced. This is confirmed by the Docosahexaenoic acid / Eicosapentaenoic acid ratio and demonstrates that EPLB and EPB can be administrated without any negative effect on biochemical composition of European sea bass. The present findings provided evidence that the tested EPSs with antibacterial and antioxidant activities can enhance immune response without negative effect on the biochemical composition. The used EPSs can be considered as a good source of natural functional aquafeed ingredients for European sea bass., (Copyright © 2020 Elsevier Ltd. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
30. Optimization of polysaccharides extraction from quince peels: partial characterization, antioxidant and antiproliferative properties.
- Author
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Dammak MI, Mzoughi Z, Chakroun I, Mansour HB, Le Cerf D, and Majdoub H
- Subjects
- Animals, Antineoplastic Agents, Phytogenic administration & dosage, Antioxidants chemistry, Caco-2 Cells, Cell Survival drug effects, Chemical Fractionation, Chromatography, Gel, Dose-Response Relationship, Drug, Fruit chemistry, Hexuronic Acids isolation & purification, Humans, Hydrogen-Ion Concentration, Magnetic Resonance Spectroscopy, Mice, Monosaccharides analysis, Monosaccharides chemistry, Plant Extracts chemistry, Polysaccharides chemistry, Spectroscopy, Fourier Transform Infrared, Temperature, Antineoplastic Agents, Phytogenic pharmacology, Antioxidants pharmacology, Polysaccharides isolation & purification, Polysaccharides pharmacology, Rosaceae chemistry
- Abstract
In this study, Box-Behnken Design was used to optimize the ultrasonic extraction of polysaccharides from quince peels (QPPs) by ascorbic acid and the effect of extraction temperature, extraction time and pH was evaluated. Under optimized conditions of temperature 90 °C, 60 min sonication time and pH = 3.26, the extraction yield, the galacturonic acid yield and the concentration of sample required to scavenge 50% of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS) values of QPPs were respectively 10.25%, 3.86% and 1.35 mg/mL. The QPPs extracted under optimum conditions was characterized by Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (
1 H NMR) and Size exclusion chromatography (SEC/MALS/VD/DRI). The monosaccharide analysis revealed that arabinose was the most abundant, followed by galactose, glucose, mannose and xylose. Moreover, QPPs showed significant antioxidant activities (2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric- reducing antioxidant power (FRAP)) and reduced viability of human Caco-2 and murine B-16 cell lines in a dose-dependent manner. Hence QPPs could be used as antitumor agent in functional foods andpharmaceutical industries.- Published
- 2020
- Full Text
- View/download PDF
31. Large-scale wearable data reveal digital phenotypes for daily-life stress detection.
- Author
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Smets E, Rios Velazquez E, Schiavone G, Chakroun I, D'Hondt E, De Raedt W, Cornelis J, Janssens O, Van Hoecke S, Claes S, Van Diest I, and Van Hoof C
- Abstract
Physiological signals have shown to be reliable indicators of stress in laboratory studies, yet large-scale ambulatory validation is lacking. We present a large-scale cross-sectional study for ambulatory stress detection, consisting of 1002 subjects, containing subjects' demographics, baseline psychological information, and five consecutive days of free-living physiological and contextual measurements, collected through wearable devices and smartphones. This dataset represents a healthy population, showing associations between wearable physiological signals and self-reported daily-life stress. Using a data-driven approach, we identified digital phenotypes characterized by self-reported poor health indicators and high depression, anxiety and stress scores that are associated with blunted physiological responses to stress. These results emphasize the need for large-scale collections of multi-sensor data, to build personalized stress models for precision medicine., Competing Interests: Competing interestsThe authors declare no competing interests.
- Published
- 2018
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32. Use of extracellular polysaccharides, secreted by Lactobacillus plantarum and Bacillus spp., as reducing indole production agents to control biofilm formation and efflux pumps inhibitor in Escherichia coli.
- Author
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Mahdhi A, Leban N, Chakroun I, Bayar S, Mahdouani K, Majdoub H, and Kouidhi B
- Subjects
- Anti-Bacterial Agents isolation & purification, Bacillus isolation & purification, Bacillus metabolism, Environmental Microbiology, Escherichia coli chemistry, Escherichia coli physiology, Food Microbiology, Hydrophobic and Hydrophilic Interactions drug effects, Lactobacillus plantarum isolation & purification, Lactobacillus plantarum metabolism, Microbial Sensitivity Tests, Polysaccharides, Bacterial isolation & purification, Quorum Sensing drug effects, Anti-Bacterial Agents pharmacology, Biofilms drug effects, Biological Transport, Active drug effects, Escherichia coli drug effects, Indoles antagonists & inhibitors, Polysaccharides, Bacterial pharmacology
- Abstract
The overuse of antibiotics and biofilm formation ability has led to the emergence of bacterial resistant strains. The combined use of several antibiotics has been found as an efficient strategy to overcome this resistance. In this study, two exopolysaccharides (EPS) obtained from Lactobacillus plantarum (EPS-Lp) and Bacillus spp. (EPS-B), isolated from a traditional Tunisian food "ricotta cheese" and hypersaline environment respectively, were used to counteract the biofilm formation and efflux pumps activities in Escherichia coli ATCC35218. The obtained results revealed that the tested EPSs can be effective against E. coli at a concentration > 1 mg/ml and were able to modulate biofilm formation by 50%. Moreover, at a concentration of 512 μg/ml, the tested EPSs inhibit the EtBr efflux in the tested bacteria and no significant difference was shown compared to cells treated with reserpine (P > 0.05). The positive effect of the tested EPSs may be due to the decrease of Indole production level proposed as a signal involved in quorum sensing and through the significant reduction of the hydrophobicity percentage between the treated and untreated cells. Overall, EPS-Lp and EPS-B, when used at appropriate concentration, may inhibit biofilm formation and reduce efflux pumps implicated in bacterial adhesion and antimicrobial resistance. These results make them an interesting candidate in the design of a new strategies to control bacterial biofilm-associated infections., (Copyright © 2018 Elsevier Ltd. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
33. Characterization of polysaccharides from Prunus amygdalus peels: Antioxidant and antiproliferative activities.
- Author
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Dammak MI, Chakroun I, Mzoughi Z, Amamou S, Mansour HB, Le Cerf D, and Majdoub H
- Subjects
- Antineoplastic Agents chemistry, Antioxidants chemistry, Chemical Phenomena, Gas Chromatography-Mass Spectrometry, Hexuronic Acids chemistry, Magnetic Resonance Spectroscopy, Phenol chemistry, Plant Extracts chemistry, Polysaccharides chemistry, Solubility, Spectroscopy, Fourier Transform Infrared, Antineoplastic Agents pharmacology, Antioxidants pharmacology, Plant Extracts pharmacology, Polysaccharides pharmacology, Prunus dulcis chemistry
- Abstract
Prunus amygdalus is used in the folk medicine that proved the interest of this plant which cures many diseases. Many researchers are interested to valorize almond waste (hull and shell) and to evaluate their biological and pharmacological activities. In this work, polysaccharides from Prunus amygdalus shell were extracted sequentially by water, ammonium oxalate and hydrochloric acid. The monosaccharide composition of polysaccharides fractions was performed by GC-MS. Water-soluble polysaccharide was found to be the most effective extracting agent with an extracted yield of 9%. The acid Soluble Polysaccharides (ASP) exhibited the highest galacturonic acid content (31.95%), the highest polysaccharides extractability (88.57%) and the lowest degree of esterification (31.76%). The different polysaccharides fractions were characterized by FTIR,
1 H NMR and SEC/MALS/VD/DRI. The antioxidant tests (DPPH, ABTS and FRAP) indicated that ASP showed even better antioxidant activities. Moreover, the result of the antiproliferative activity against Caco-2 and B-16 cells showed that ASP exhibited strong cytotoxicity ability which confirmed that the Prunus amygdalus peels may comprise the natural raw materials for new drug and functional food., (Copyright © 2018 Elsevier B.V. All rights reserved.)- Published
- 2018
- Full Text
- View/download PDF
34. Motility, biofilm formation, apoptotic effect and virulence gene expression of atypical Salmonella Typhimurium outside and inside Caco-2 cells.
- Author
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Chakroun I, Mahdhi A, Morcillo P, Cordero H, Cuesta A, Bakhrouf A, Mahdouani K, and Esteban MÁ
- Subjects
- Apoptosis, Bacterial Proteins metabolism, Caco-2 Cells, Gene Expression Regulation, Bacterial, Host-Pathogen Interactions, Humans, Salmonella typhimurium cytology, Salmonella typhimurium genetics, Seawater analysis, Seawater microbiology, Sodium Chloride analysis, Sodium Chloride metabolism, Virulence Factors metabolism, Bacterial Proteins genetics, Biofilms, Salmonella Infections microbiology, Salmonella typhimurium physiology, Virulence Factors genetics
- Abstract
Disease outbreaks related to waterborne pathogen contamination throughout the world as well as challenges that lie ahead for addressing persistent infection are of renewed interest. In this research, we studied the effects of prolonged exposure of Salmonella enterica serovar Typhimurium to the cues encountered in the extracellular environment particularly in seawater microcosm on bacterial virulence and subsequent infection in Caco-2 cells. Our data show a significant difference in biofilm formation, swimming and swarming motilities between normal and stressed cells of S. Typhimurium under differing NaCl conditions (P < 0.05). Interestingly, adhesion, invasion and apoptotic activity to Caco-2 epithelial cells were determined during infection with normal and stressed Salmonella. Furthermore, we compared the expression of SPI-1 virulence genes (sopA, sopB, sopD, sopE2 and hilA) of normal and stressed S. Typhimurium in response to salt conditions encountered in the extracellular environment in LB broth and after epithelial cell exposure. The interest of the present study is due to the fact that to investigate the bacterial survival strategies during its movement from the natural surroundings to the host cell is fundamental to our understanding of the infection process during the host-pathogen interactions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
35. Ozone treatment of polysaccharides from Arthrocnemum indicum: Physico-chemical characterization and antiproliferative activity.
- Author
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Mzoughi Z, Chakroun I, Hamida SB, Rihouey C, Mansour HB, Le Cerf D, and Majdoub H
- Subjects
- Cell Line, Tumor, Cell Proliferation drug effects, Humans, Molecular Weight, Monosaccharides analysis, Viscosity, Amaranthaceae chemistry, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Chemical Phenomena, Ozone chemistry, Polysaccharides chemistry, Polysaccharides pharmacology
- Abstract
The isolation, purification and ozone depolymerization of polysaccharides from Arthrocnemum indicum as well as the evaluation of their antiproliferative capacities were investigated. The ozone treatment for various reaction times (0, 15, 30, 45 and 60min) was employed as degradation method in order to attain lower molecular weight product with stronger antiproliferative property. According to FTIR,
1 H NMR and UV-vis analysis, the main chain of ozonolytic degraded polysaccharides could be preserved. The monosaccharide composition, which was determined via GC/MS analysis, showed that extracted polysaccharides were of type of arabinan-rich pectic polysaccharides. Macromolecular characteristics as well as intrinsic viscosity of the degraded polysaccharides were performed by size exclusion chromatography before and after ozone treatment. These experiments showed that intrinsic viscosity and molecular weight (Mn and Mw) of degraded samples decreased with increase in reaction time. Furthermore, preliminary antiproliferative tests indicated that degraded polysaccharide for 1h showed even better antiproliferative capacity., (Copyright © 2017 Elsevier B.V. All rights reserved.)- Published
- 2017
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36. Assessment of the correlation among antibiotic resistance, adherence to abiotic and biotic surfaces, invasion and cytotoxicity of Pseudomonas aeruginosa isolated from diseased gilthead sea bream.
- Author
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Lamari F, Chakroun I, and Rtimi S
- Subjects
- Animals, Drug Resistance, Microbial, Erythromycin pharmacology, Gentamicins pharmacology, Hep G2 Cells, Humans, Pseudomonas aeruginosa drug effects, Sea Bream metabolism, Anti-Bacterial Agents pharmacology
- Abstract
Improper uses of antibiotics to treat fish disease pose an increase of multidrug resistance in Pseudomonas aeruginosa. In order to escape host antimicrobial agents and induce cytotoxicity, different virulence properties are needed by these bacteria such as, biofilm formation, adhesion and invasion ability. This study was conducted to isolate Pseudomonas aeruginosa from diseased cultured gilthead sea bream. Seventeen isolates of Pseudomonas aeruginosa were identified by PCR. All of the isolates tested were susceptible to Gentamicin and Ciprofloxacin. Highest level of resistance was observed against Erythromycin, Ampicillin and Tetracycline. Among the 17 isolates, 11 showed multi-drug resistance. The isolates were screened for biofilm formation in abiotic surfaces, adherence, invasion and cytotoxicity against Hep-2 cells. We found that some strains were able to adhere to abiotic and biotic surface and to enter inside Hep-2 cells. Using cytochalasin D inhibitor, we observed a significant decrease in invasion of epithelial cells. The 17 washed bacterial cells induce variable degree of cytotoxicity. However, no cytotoxic effects on Hep-2 cells were obtained among the totality of cell free filtrate of Pseudomonas strains. By studying the relationship between different virulence properties, a significant positive correlation was obtained between both biofilm formation and adherence, and between adherence and invasion to epithelial cells. Subsequently, we found that the mean values of adhesion and invasion in the MDR group were significantly higher than those observed in the non-MDR group. Likewise, a significant positive correlation was found among adhesive and invasive capacities of Pseudomonas strains and their antibiotic resistance phenotypes., (Copyright © 2017 Elsevier B.V. All rights reserved.)
- Published
- 2017
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37. Culture conditions improvement of Crassostrea gigas using a potential probiotic Bacillus sp strain.
- Author
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Fdhila K, Haddaji N, Chakroun I, Dhiaf A, Macherki MEE, Khouildi B, Lamari F, Chaieb K, Abid N, Marzougui H, Khouadja S, and Missaoui H
- Subjects
- Animals, Aquaculture methods, Cell Survival drug effects, Hemocytes drug effects, Hemocytes physiology, Indigo Carmine metabolism, Seawater chemistry, Vibrio growth & development, Bacillus growth & development, Crassostrea growth & development, Probiotics administration & dosage
- Abstract
It is well demonstrated that some probiotics improve rearing water quality and thereby have beneficial effects on reared organisms. We conducted this study to determine the effect of Bacillus consortium on Crassostrea gigas reared in contemned seawater with indigo dye priory treated with Bacillus or no treated. This effect was studied by assessing hemocytes death using flow cytometry analysis. We found that the percentage of decolorization of indigo dye in polluted seawater in presence of C. gigas increased from 41% to 90% when using Bacillus consortium. In these conditions, the hemocytes mortality of reared C. gigas decreased from 87% to 56%. We have demonstrated also that seawater contemned with priory treated indigo with Bacillus consortium is less toxic than seawater contemned with the no treated indigo. The percentage of hemocytes death is 81% for the contemned seawater with indigo and 56% for no contemned seawater. This consortium shows a protector effect of C. gigas against Vibrio harveyi contemning reared seawater., (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
38. Extracellular polysaccharide derived from potential probiotic strain with antioxidant and antibacterial activities as a prebiotic agent to control pathogenic bacterial biofilm formation.
- Author
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Mahdhi A, Leban N, Chakroun I, Chaouch MA, Hafsa J, Fdhila K, Mahdouani K, and Majdoub H
- Subjects
- Animals, Artemia drug effects, Ascorbic Acid metabolism, Biofilms growth & development, Cell Line, Tumor, Cell Survival drug effects, Free Radical Scavengers, Gallic Acid metabolism, Humans, Hydrophobic and Hydrophilic Interactions, Lactobacillus plantarum chemistry, Linoleic Acid metabolism, Microbial Sensitivity Tests, Polysaccharides, Bacterial chemistry, Toxicity Tests, Anti-Bacterial Agents pharmacology, Antioxidants pharmacology, Bacteria drug effects, Polysaccharides, Bacterial pharmacology, Prebiotics, Probiotics chemistry
- Abstract
Because of their functional diversity, bioactive compounds are becoming a new biocontrol agent to limit biofilm formation by pathogens. In this study, the physico-chemical characterization of an exopolysaccharide (EPS) isolated from Lactobacillus plantarum (EPLB) was characterized and its in vitro effect on biofilm formation was studied. The EPS had a molecular weight of 36 kDa and polydispersity index estimated to be 1.2. The tested EPLB had an antibacterial activity, with a Minimal Inhibition Concentration (MIC) values ranging between 1 mg/ml and 10 mg/ml, displayed an antibiofilm effect concentration dependent on Gram positive and negative strains. Among the pathogenic strains, 2 out of 4 appeared to be more than 50% inhibited in their biofilm development by the EPS. The antibiofilm activity can be due to the ability of the EPS to influence the function of biological membranes like hydrophobicity that decreased (P < 0.05) when the EPS was used at a concentration of 512 μg/ml. This EPS without cytotoxic effect, showed an antioxidant effect on the quenching of DPPH radicals and the inhibition of lipid peroxidation with a percentage of 64% and 66%, respectively. Taken together these biological properties, EPLB can be considered as a potential prebiotic agent in the design of new therapeutic strategies for bacterial biofilm-associated infections., (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
39. Adhesion, invasion, cytotoxic effect and cytokine production in response to atypical Salmonella Typhimurium infection.
- Author
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Chakroun I, Cordero H, Mahdhi A, Morcillo P, Fedhila K, Cuesta A, Bakhrouf A, Mahdouani K, and Esteban MÁ
- Subjects
- Caco-2 Cells cytology, Caco-2 Cells drug effects, Culture Media, Drug Resistance, Bacterial, Environment, Host-Pathogen Interactions immunology, Humans, Interleukin-6 metabolism, Interleukin-8 metabolism, Microbial Sensitivity Tests, Microscopy, Electron, Transmission, Models, Biological, Salmonella typhimurium growth & development, Salmonella typhimurium pathogenicity, Seawater microbiology, Stress, Physiological, Time Factors, Bacterial Adhesion drug effects, Cytokines metabolism, Cytokines pharmacology, Salmonella Infections immunology, Salmonella typhimurium drug effects, Salmonella typhimurium immunology
- Abstract
Pathogenic bacteria such as Salmonella have the ability to respond to a wide variety of environmental stimuli. These responses allow them to survive and withstand insults both of an external location as well as within the host. The aim of this study was to investigate the effect of preadaptation in stressful conditions encountered in seawater microcosms for different periods of time on Salmonella Typhimurium survival, antibiotic susceptibility and interactions with Caco-2 cells. These results showed that the number of bacterial cells depends from the periods of stress in culture medium, highlighting the importance of using the right culture medium for the enumeration of stressed bacteria. The antibiotic resistance of starved cells was modified and their exposure to stressful conditions in seawater during 12 months significantly increased adhesion, invasion and cytotoxic activities on Caco-2 cells. Moreover, cellular cytokines IL-6 and IL-8 secretions were up-regulated. Present results seem to suggest that the preadaptation of S. Typhimurium in seawater microcosms affect the cultural characters by the appearance of the atypical cells that may play a critical role in the intestinal infection and in the systemic spread of the disease. These findings are very important to understand bacterial responses to changing conditions and explain the persistence of these atypical in eukaryotic cells., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
40. [Assessing user satisfaction, an objective for quality of care].
- Author
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Séné-Bourgeois M, Mathieu-Chakroun I, and Margat A
- Subjects
- Health Care Reform, Humans, Primary Health Care methods, Primary Health Care organization & administration, Primary Health Care standards, Quality Assurance, Health Care legislation & jurisprudence, Quality Improvement legislation & jurisprudence, Quality Improvement organization & administration, Quality of Health Care legislation & jurisprudence, Quality of Health Care standards, Surveys and Questionnaires, Patient Satisfaction, Quality Assurance, Health Care methods, Quality Indicators, Health Care legislation & jurisprudence
- Abstract
The assessment of user satisfaction constitutes a key indicator of the quality of care. It can be envisaged either as part of an internal strategy which favours the improvement of practices, an external strategy whose focus is more commercial and/or an exploratory strategy to develop care models. User satisfaction is expressed in particular through complaint letters and discharge questionnaires. These regulated schemes enable quality to be approached on an individual and collective level., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
41. Glucomannan's protective effect on the virulence of Vibrio splendidus in pacific oyster.
- Author
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Fdhila K, Haddaji N, Chakroun I, Macherki MEE, Nefzi F, and Bakhrouf A
- Subjects
- Animal Feed analysis, Animals, Candida chemistry, Diet, Hemocytes drug effects, Hemocytes microbiology, Mannans pharmacology, Vibrio physiology, Crassostrea drug effects, Crassostrea immunology, Immunity, Innate drug effects, Vibrio drug effects
- Abstract
We examine the effect of Glucomannan, extracted from Candida utilis yeast, on immune parameters and resistance to Vibrio splendidus of Crassostreagigas. Our results showed that Glucomannan was a successful anti-adhesive molecule; it exhibited a stronger inhibitory effect on adhesion of Vibrio splendidus in infected Crassostreagigas. Vibrio splendidus viable cells number declined after incubation with Glucomannan. Furthermore, the Glucomannan diet showed higher activity to trigger the immune response against bacteria. Glucomannan applications, in biological control of seafood associated pathogens can be an alternative solution, providing consumer with a product of good quality owing to the use of 40 non-toxic compounds. Based on our results, Glucomannan could be used as a bio-protective culture in oyster's depuration to prevent Vibrio splendidus growth., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
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42. Genome-wide association between Six4, MyoD, and the histone demethylase Utx during myogenesis.
- Author
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Chakroun I, Yang D, Girgis J, Gunasekharan A, Phenix H, Kærn M, and Blais A
- Subjects
- Animals, Female, Genome-Wide Association Study, Histone Demethylases genetics, Homeodomain Proteins genetics, Mice, MyoD Protein genetics, Trans-Activators genetics, Histone Demethylases metabolism, Homeodomain Proteins metabolism, Muscle Development physiology, Muscle, Skeletal metabolism, MyoD Protein metabolism, Regeneration physiology, Trans-Activators metabolism
- Abstract
Adult skeletal muscles can regenerate after injury, due to the presence of satellite cells, a quiescent population of myogenic progenitor cells. Once activated, satellite cells repair the muscle damage by undergoing myogenic differentiation. The myogenic regulatory factors (MRFs) coordinate the process of progenitor differentiation in cooperation with other families of transcription factors (TFs). The Six1 and Six4 homeodomain TFs are expressed in developing and adult muscle and Six1 is critical for embryonic and adult myogenesis. However, the lack of a muscle developmental phenotype in Six4-null mice, which has been attributed to compensation by other Six family members, has discouraged further assessment of the role of Six4 during adult muscle regeneration. By employing genome-wide approaches to address the function of Six4 during adult skeletal myogenesis, we have identified a core set of muscle genes coordinately regulated in adult muscle precursors by Six4 and the MRF MyoD. Throughout the genome of differentiating adult myoblasts, the cooperation between Six4 and MyoD is associated with chromatin repressive mark removal by Utx, a demethylase of histone H3 trimethylated at lysine 27. Among the genes coordinately regulated by Six4 and MyoD are several genes critical for proper in vivo muscle regeneration, implicating a role of Six4 in this process. Using in vivo RNA interference of Six4, we expose an uncompensated function of this TF during muscle regeneration. Together, our results reveal a role for Six4 during adult muscle regeneration and suggest a widespread mechanism of cooperation between Six4 and MyoD., (© FASEB.)
- Published
- 2015
- Full Text
- View/download PDF
43. Six1 regulates MyoD expression in adult muscle progenitor cells.
- Author
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Liu Y, Chakroun I, Yang D, Horner E, Liang J, Aziz A, Chu A, De Repentigny Y, Dilworth FJ, Kothary R, and Blais A
- Subjects
- Animals, Binding Sites genetics, Cell Differentiation genetics, Cell Differentiation physiology, Chromatin genetics, Female, Gene Expression Regulation, Developmental genetics, Genes, Reporter genetics, Homeodomain Proteins metabolism, Mice, Mice, Inbred C57BL, Muscle Development genetics, Muscle Development physiology, Muscle, Skeletal metabolism, MyoD Protein metabolism, Myoblasts metabolism, Myoblasts physiology, Myogenic Regulatory Factors genetics, Myogenic Regulatory Factors metabolism, Regeneration genetics, Regeneration physiology, Satellite Cells, Skeletal Muscle metabolism, Stem Cells metabolism, Transcription Factors genetics, Transcription Factors metabolism, Homeodomain Proteins genetics, Muscle, Skeletal physiology, MyoD Protein genetics, Satellite Cells, Skeletal Muscle physiology, Stem Cells physiology
- Abstract
Quiescent satellite cells are myogenic progenitors that enable regeneration of skeletal muscle. One of the early events of satellite cell activation following myotrauma is the induction of the myogenic regulatory factor MyoD, which eventually induces terminal differentiation and muscle function gene expression. The purpose of this study was to elucidate the mechanism by which MyoD is induced during activation of satellite cells in mouse muscle undergoing regeneration. We show that Six1, a transcription factor essential for embryonic myogenesis, also regulates MyoD expression in muscle progenitor cells. Six1 knock-down by RNA interference leads to decreased expression of MyoD in myoblasts. Chromatin immunoprecipitation assays reveal that Six1 binds the Core Enhancer Region of MyoD. Further, transcriptional reporter assays demonstrate that Core Enhancer Region reporter gene activity in myoblasts and in regenerating muscle depends on the expression of Six1 and on Six1 binding sites. Finally, we provide evidence indicating that Six1 is required for the proper chromatin structure at the Core Enhancer Region, as well as for MyoD binding at its own enhancer. Together, our results reveal that MyoD expression in satellite cells depends on Six1, supporting the idea that Six1 plays an important role in adult myogenesis, in addition to its role in embryonic muscle formation.
- Published
- 2013
- Full Text
- View/download PDF
44. Effect of long-term starvation in salty microcosm on biofilm formation and motility in Pseudomonas aeruginosa.
- Author
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Elabed H, Maatallah M, Hamza R, Chakroun I, Bakhrouf A, and Gaddour K
- Subjects
- Adenosylmethionine Decarboxylase biosynthesis, Bacterial Adhesion, DNA, Bacterial chemistry, DNA, Bacterial genetics, Electron Transport Complex IV biosynthesis, Gene Expression Profiling, Molecular Sequence Data, Pseudomonas aeruginosa growth & development, Pseudomonas aeruginosa metabolism, Sequence Analysis, DNA, Sodium Chloride metabolism, Biofilms growth & development, Locomotion, Pseudomonas aeruginosa physiology
- Abstract
The development of antibiotic resistance in the opportunistic pathogen Pseudomonas aeruginosa is a major cause of the pathogen's morbidity and is strongly correlated with the biofilm formation. Motility and adherence capacity in long-term stressed cells have not been extensively analyzed even though P. aeruginosa considered a model organism for the study of biofilm formation. In this investigation, P. aeruginosa ATCC 27853 strain has been stored for 12 months in LB broth with 0.5 M NaCl. Several experiments demonstrated that the strain recovery from the salty microcosm had the ability to increase the biofilm formation and to reduce motility comparing with that of the original strain. To identify genes involved in the regulation of biofilm and/or in stress response by the recovered P. aeruginosa, differential display "DDRT-PCR" technique was used. The genes speD and ccoN2, coding, respectively, for an S-adenosylmethionine decarboxylase and Cbb3-type cytochrome oxidase, were identified in recovered strain of P. aeruginosa ATCC 27853 as two differentially expressed gene fragments. A comparison of the biofilm produced by the wild-type strain PA14 and the transposon insertion mutant for speD gene suggested that spermidine has a potential role in the adaptive response in P. aeruginosa incubated in long-term stress conditions.
- Published
- 2013
- Full Text
- View/download PDF
45. Cooperation between myogenic regulatory factors and SIX family transcription factors is important for myoblast differentiation.
- Author
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Liu Y, Chu A, Chakroun I, Islam U, and Blais A
- Subjects
- Animals, Cell Differentiation, Cell Line, Genome, Homeodomain Proteins physiology, Humans, Mice, Myoblasts, Skeletal cytology, Trans-Activators physiology, Transcriptional Activation, Homeodomain Proteins metabolism, Muscle Development genetics, Myoblasts, Skeletal metabolism, Myogenic Regulatory Factors metabolism, Trans-Activators metabolism
- Abstract
Precise regulation of gene expression is crucial to myogenesis and is thought to require the cooperation of various transcription factors. On the basis of a bioinformatic analysis of gene regulatory sequences, we hypothesized that myogenic regulatory factors (MRFs), key regulators of skeletal myogenesis, cooperate with members of the SIX family of transcription factors, known to play important roles during embryonic skeletal myogenesis. To this day little is known regarding the exact molecular mechanism by which SIX factors regulate muscle development. We have conducted a functional genomic study of the role played by SIX1 and SIX4 during the differentiation of skeletal myoblasts, a model of adult muscle regeneration. We report that SIX factors cooperate with the members of the MRF family to activate gene expression during myogenic differentiation, and that their function is essential to this process. Our findings also support a model where SIX factors function not only 'upstream' of the MRFs during embryogenesis, but also 'in parallel' to them during myoblast differentiation. We have identified new essential nodes that depend on SIX factor function, in the myogenesis regulatory network, and have uncovered a novel way by which MRF function is modulated during differentiation.
- Published
- 2010
- Full Text
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46. The role of NF-kappaB in mediating the anti-inflammatory effects of IL-10 in intestinal epithelial cells.
- Author
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Al-Ashy R, Chakroun I, El-Sabban ME, and Homaidan FR
- Subjects
- Animals, Cells, Cultured, Cyclooxygenase 2 metabolism, Dinoprostone metabolism, I-kappa B Kinase metabolism, Inflammation metabolism, Interleukin-1 pharmacology, Mice, NF-kappa B antagonists & inhibitors, Receptors, Interleukin-1 metabolism, Receptors, Interleukin-10 metabolism, Epithelial Cells drug effects, Epithelial Cells metabolism, Interleukin-10 pharmacology, Intestinal Mucosa metabolism, Intestines drug effects, NF-kappa B metabolism
- Abstract
In inflammatory bowel disease, cells that infiltrate the mucosa regulate intestinal epithelial cell function partly through release of pro- and anti-inflammatory cytokines. The aim of this study is to evaluate the role of the anti-inflammatory cytokine, IL-10, on normal mouse intestinal epithelial cells (Mode-K) in the absence or presence of IL-1. Western blotting assays and immunocytochemistry were used to identify the presence of IL-1 and IL-10 receptors on Mode-K cells; and electrophoretic mobility shift assays were used to study the activation of NF-kappaB transcription factor. Stimulation of Mode-K cells with IL-1 or IL-10 did not modify IL-1 and IL-10 receptor expression levels. IL-1 induced the synthesis of the enzyme cyclooxygenase-2 (COX-2) through the activation and translocation of p65 subunit of NF-kappaB. Inhibition of translocated p65 binding to DNA, inhibited COX-2 production and induced apoptosis. IL-10 inhibited IL-1-induced effects on IKB-alpha and IKB-beta proteins through stabilizing these proteins; subsequently causing inhibition of NF-kappaB translocation to the nucleus and any subsequent induction of COX-2. These data support a role for IL-10 in the regulation of IEC function under inflammatory conditions and the involvement of COX-2 in inhibiting apoptosis in mouse intestinal epithelial cells.
- Published
- 2006
- Full Text
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47. Stage-specific effect of N-(4-hydroxyphenyl)retinamide on cell growth in squamous cell carcinogenesis.
- Author
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Kabbout M, Hatoum A, Abou-Lteif G, Chakroun I, Homaidan FR, and Darwiche N
- Subjects
- Animals, Benzimidazoles metabolism, Cell Division drug effects, Cells, Cultured, G1 Phase drug effects, Keratinocytes pathology, Mice, Mice, Inbred BALB C, Neoplasm Staging, Nevus, Spindle Cell pathology, Propidium, Receptors, Retinoic Acid metabolism, Ribonucleases metabolism, Tretinoin pharmacology, Antineoplastic Agents pharmacology, Apoptosis drug effects, Carcinoma, Squamous Cell pathology, Cell Transformation, Neoplastic, Fenretinide pharmacology, Keratinocytes drug effects, Papilloma pathology
- Abstract
Squamous cell carcinoma (SCC) is the most prevalent form of epithelial cancer. SCC results when normal epithelial cells undergo multiple neoplastic changes that culminate in the evolution of an invasive cancer. Retinoids are commonly used as chemopreventive and treatment agents in skin cancer; however, SCC progression is accompanied by a gradual loss of retinoid responsiveness. The synthetic retinoid N-(4-hydroxyphenyl)retinamide (HPR) has shown promising anti-neoplastic activity in a variety of tumor cells, including those that are resistant to all-trans retinoic acid (t-RA). We investigated the effect of HPR on growth and apoptosis of squamous cells at different stages of carcinogenesis. We then determined if retinoic acid receptor (RAR) overexpression affected the outcome of HPR treatment. To model SCC malignant progression, we used a panel of murine keratinocytes representing different stages of squamous cell carcinogenesis. This panel consisted of primary keratinocytes, SP1 and 308 papilloma cell lines, the PAM-212 squamous carcinoma cell line, and the spindle I7 cell line. With the exception of the primary keratinocytes, all cells were unresponsive to t-RA treatment. Pharmacological concentrations of HPR were non-cytotoxic to all keratinocytes tested and HPR sensitivity was stage-dependent, with the papilloma cell lines being the most sensitive, and the spindle cells being the most resistant. Overexpression of RARgamma in SP1 papilloma cells enhanced growth suppression and apoptosis induction by HPR. HPR-induced growth suppression was accompanied by a simultaneous block in the G(1) phase of the cell cycle in RAR-transduced and control SP1 cells and differential regulation of cell cycle and apoptotic mediators., (Copyright 2004 Wiley-Liss, Inc.)
- Published
- 2004
- Full Text
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48. Regulation of nuclear factor-kappaB in intestinal epithelial cells in a cell model of inflammation.
- Author
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Homaidan FR, Chakroun I, and El-Sabban ME
- Subjects
- Animals, Apoptosis immunology, Apoptosis Regulatory Proteins, Cell Line, Ceramides pharmacology, Cysteine Proteinase Inhibitors pharmacology, Enteritis pathology, Epithelial Cells drug effects, Epithelial Cells immunology, I-kappa B Proteins metabolism, Interleukin-1 pharmacology, Leupeptins pharmacology, NF-KappaB Inhibitor alpha, Proteins genetics, Proto-Oncogene Proteins metabolism, Proto-Oncogene Proteins c-bcl-2 genetics, RNA, Messenger metabolism, bcl-X Protein, Enteritis metabolism, Epithelial Cells metabolism, Intestinal Mucosa cytology, Intestinal Mucosa immunology, NF-kappa B metabolism
- Abstract
Background: Interleukin-1 (IL-1), an inflammatory cytokine whose levels are elevated in inflamed mucosa, causes part of its effect on intestinal epithelial cells (IEC) through inducing ceramide production., Aim: To study the role of nuclear factor-kappaB (NF-kappaB), a pro-inflammatory and anti-apoptotic factor, in IL-1-treated IEC., Methods: NF-kappaB activity and levels of apoptotic proteins were assessed by electrophoretic mobility shift assay and RNA-protection assay, respectively., Results: IL-1 and ceramide, which have been shown to partially mediate IL-1 effects on IEC, activated NF-kappaB levels significantly. This activation was due to a decrease in IkappaB-alpha and IkappaB-beta protein levels. Moreover, the ratio of mRNA levels of anti-apoptotic to pro-apoptotic proteins was significantly increased in IL-1-treated IEC., Conclusion: NF-kappaB may play a key role in the regulation of the expression of pro-inflammatory and/or apoptotic genes in inflammatory bowel disease, making this protein an attractive target for therapeutic intervention.
- Published
- 2003
- Full Text
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49. Protein regulators of eicosanoid synthesis: role in inflammation.
- Author
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Homaidan FR, Chakroun I, Haidar HA, and El-Sabban ME
- Subjects
- Animals, Arthritis, Rheumatoid enzymology, Arthritis, Rheumatoid metabolism, Humans, Inflammatory Bowel Diseases enzymology, Inflammatory Bowel Diseases metabolism, Eicosanoids biosynthesis, Inflammation enzymology, Inflammation metabolism, Inflammation Mediators metabolism
- Abstract
A variety of factors contribute to the complex course of inflammation. Microbiological, immunological and toxic agents can initiate the inflammatory response by activating a variety of humoral and cellular mediators. In the early phase of inflammation, excessive amounts of cytokines and inflammatory mediators are released. These factors activate, in addition to other signaling pathways, the lipid synthesis pathways, which play a crucial role in the pathogenesis of organ dysfunction. Arachidonic acid (AA), the precursor of pro-inflammatory eicosanoids, is released from membrane phospholipids by the action of phospholipase A(2) (PLA(2)), and is metabolized to prostaglandins (PGs) and leukotrienes (LTs) by the action of cyclooxygenase (COX) and lipoxygenase (LO) enzymes, respectively. Disordered activation of PLA(2), LO and COX enzymes have been implicated in many inflammatory diseases. PLA(2) is activated by phospholipase-A(2)-activating protein (PLAP) and LO by 5-lipoxygenase-activating protein (FLAP). The inducible form of COX-2 enzyme, which is usually not present under basal conditions, is induced in inflammation. In this article the function of these enzymes in eicosanoid synthesis, their regulation, and their implication in inflammatory disorders will be reviewed. The properties, function and regulation of the protein activators PLAP and FLAP will also be discussed.
- Published
- 2002
- Full Text
- View/download PDF
50. IL-1 stimulates ceramide accumulation without inducing apoptosis in intestinal epithelial cells.
- Author
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Homaidan FR, El-Sabban ME, Chakroun I, El-Sibai M, and Dbaibo GS
- Subjects
- Animals, Cell Cycle drug effects, Ceramides pharmacology, Humans, Intestinal Mucosa metabolism, Intestinal Mucosa pathology, Mice, Tumor Suppressor Protein p53 physiology, Apoptosis drug effects, Ceramides biosynthesis, Interleukin-1 pharmacology, Intestinal Mucosa drug effects
- Abstract
Background: In inflammatory bowel disease (IBD), cytokine levels (such as interleukin-1 (IL-1)) are elevated. We have shown previously that IL-1 activates phospholipid signaling pathways in intestinal epithelial cells (EEC), leading to increased ceramide levels., Aim: To determine whether ceramide induces apoptosis in IEC., Methods: Apoptosis was evaluated by annexin-V binding or Hoechst nuclear staining. Levels of bcl-2, bcl-x, bax, p53 and p21 were determined by Western blotting, and celi cycle analysis was determined by flow cytometry., Results: IL-1 increased ceramide accumulation in a time-dependent and concentration-dependent manner with a peak response at 4 h, with [IL-1] = 30 ng/ml. Neither IL-1 nor ceramide induced apoptosis in EEC, but they increased bcl-2 levels and decreased bax and p21 levels without affecting bcl-x and p53 levels. They also caused a slight but significant increase in the G2/M phase. These data suggest a role for ceramide in IBD and suggest a possible mechanism for the enhanced tumorigenic activity in IBD patients.
- Published
- 2002
- Full Text
- View/download PDF
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