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35 result(s) for "Hassoun, Mohamed"
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A droplet-based microfluidic chip as a platform for leukemia cell lysate identification using surface-enhanced Raman scattering
A new approach is presented for cell lysate identification which uses SERS-active silver nanoparticles and a droplet-based microfluidic chip. Eighty-nanoliter droplets are generated by injecting silver nanoparticles, KCl as aggregation agent, and cell lysate containing cell constituents, such as nucleic acids, carbohydrates, metabolites, and proteins into a continuous flow of mineral oil. This platform enables accurate mixing of small volumes inside the meandering channels of the quartz chip and allows acquisition of thousands of SERS spectra with 785 nm excitation at an integration time of 1 s. Preparation of three batches of three leukemia cell lines demonstrated the experimental reproducibility. The main advantage of a high number of reproducible spectra is to apply statistics for large sample populations with robust classification results. A support vector machine with leave-one-batch-out cross-validation classified SERS spectra with sensitivities, specificities, and accuracies better than 99% to differentiate Jurkat, THP-1, and MONO-MAC-6 leukemia cell lysates. This approach is compared with previous published reports about Raman spectroscopy for leukemia detection, and an outlook is given for transfer to single cells.
Chemoorganoautotrophic lifestyle of the anaerobic enrichment culture N47 growing on naphthalene
In almost all respiratory organisms, organic substrates are degraded via catabolic processes to the central metabolite acetyl-CoA which is then oxidized to CO 2 for energy metabolism or used as a building block for anabolism. Most microorganisms have either the closed tricarboxylic acid cycle or the complete Wood-Ljungdahl-pathway for acetyl-CoA oxidation, but the sulfate-reducing, naphthalene-degrading culture N47 possesses both completely. Combining 13 C- labeled substrates and mass-specific GC-MS analysis of amino acids and fatty acids with enzyme activity assays suggests that N47 has a chemoorganoautotrophic metabolism degrading complex organic substrates such as naphthalene. Surprisingly, however, the biomass is mainly produced from acetyl-CoA generated de novo via CO 2 -fixation. This metabolism probably requires both a complete Wood-Ljungdahl pathway for acetyl-CoA oxidation and a reverse tricarboxylic acid cycle for CO 2 fixation. Based on genome analysis, this chemoorganoautotrophic metabolism seems to also occur in other sulfate-reducers and anaerobic ammonium-oxidizers.
Surface-enhanced Raman spectroscopy of cell lysates mixed with silver nanoparticles for tumor classification
The throughput of spontaneous Raman spectroscopy for cell identification applications is limited to the range of one cell per second because of the relatively low sensitivity. Surface-enhanced Raman scattering (SERS) is a widespread way to amplify the intensity of Raman signals by several orders of magnitude and, consequently, to improve the sensitivity and throughput. SERS protocols using immuno-functionalized nanoparticles turned out to be challenging for cell identification because they require complex preparation procedures. Here, a new SERS strategy is presented for cell classification using non-functionalized silver nanoparticles and potassium chloride to induce aggregation. To demonstrate the principle, cell lysates were prepared by ultrasonication that disrupts the cell membrane and enables interaction of released cellular biomolecules to nanoparticles. This approach was applied to distinguish four cell lines – Capan-1, HepG2, Sk-Hep1 and MCF-7 – using SERS at 785 nm excitation. Six independent batches were prepared per cell line to check the reproducibility. Principal component analysis was applied for data reduction and assessment of spectral variations that were assigned to proteins, nucleotides and carbohydrates. Four principal components were selected as input for classification models based on support vector machines. Leave-three-batches-out cross validation recognized four cell lines with sensitivities, specificities and accuracies above 96%. We conclude that this reproducible and specific SERS approach offers prospects for cell identification using easily preparable silver nanoparticles.
Carbon Monoxide Improves Cardiac Function and Mitochondrial Population Quality in a Mouse Model of Metabolic Syndrome
Metabolic syndrome induces cardiac dysfunction associated with mitochondria abnormalities. As low levels of carbon monoxide (CO) may improve myocardial and mitochondrial activities, we tested whether a CO-releasing molecule (CORM-3) reverses metabolic syndrome-induced cardiac alteration through changes in mitochondrial biogenesis, dynamics and autophagy. Mice were fed with normal diet (ND) or high-fat diet (HFD) for twelve weeks. Then, mice received two intraperitoneal injections of CORM-3 (10 mg x kg(-1)), with the second one given 16 hours after the first. Contractile function in isolated hearts and mitochondrial parameters were evaluated 24 hours after the last injection. Mitochondrial population was explored by electron microscopy. Changes in mitochondrial dynamics, biogenesis and autophagy were assessed by western-blot and RT-qPCR. Left ventricular developed pressure was reduced in HFD hearts. Mitochondria from HFD hearts presented reduced membrane potential and diminished ADP-coupled respiration. CORM-3 restored both cardiac and mitochondrial functions. Size and number of mitochondria increased in the HFD hearts but not in the CORM-3-treated HFD group. CORM-3 modulated HFD-activated mitochondrial fusion and biogenesis signalling. While autophagy was not activated in the HFD group, CORM-3 increased the autophagy marker LC3-II. Finally, ex vivo experiments demonstrated that autophagy inhibition by 3-methyladenine abolished the cardioprotective effects of CORM-3. CORM-3 may modulate pathways controlling mitochondrial quality, thus leading to improvements of mitochondrial efficiency and HFD-induced cardiac dysfunction.
Inhibition of mitochondrial respiration mediates apoptosis induced by the anti-tumoral alkaloid lamellarin D
Lamellarin D (Lam D), a marine alkaloid, exhibits a potent cytotoxicity against many different tumors. The pro-apoptotic function of Lam D has been attributed to its direct induction of mitochondrial permeability transition (MPT). This study was undertaken to explore the mechanisms through which Lam D promotes changes in mitochondrial function and as a result apoptosis. The use of eight Lam derivatives provides useful structure-apoptosis relationships. We demonstrate that Lam D and structural analogues induce apoptosis of cancer cells by acting directly on mitochondria inducing reduction of mitochondrial membrane potential, swelling and cytochrome c release. Cyclosporin A, a well-known inhibitor of MPT, completely prevents mitochondrial signs of apoptosis. The drug decreases calcium uptake by mitochondria but not by microsomes indicating that Lam D-dependent permeability is specific to mitochondrial membranes. In addition, upon Lam D exposure, a rapid decline of mitochondrial respiration and ATP synthesis occurs in isolated mitochondria as well as in intact cells. Evaluation of the site of action of Lam D on the electron-transport chain revealed that the activity of respiratory chain complex III is reduced by a half. To determine whether Lam D could induce MPT-dependent apoptosis by inhibiting mitochondrial respiration, we generated respiration-deficient cells (ρ0) derived from human melanoma cells. In comparison to parental cells, ρ0 cells are totally resistant to the induction of MPT-dependent apoptosis by Lam D. Our results indicate that functional mitochondria are required for Lam D-induced apoptosis. Inhibition of mitochondrial respiration is responsible for MPT-dependent apoptosis of cancer cells induced by Lam-D.
Macrophage Migration Inhibitory Factor Inhibition Is Deleterious for High-Fat Diet-Induced Cardiac Dysfunction
Development of metabolic syndrome is associated with impaired cardiac performance, mitochondrial dysfunction and pro-inflammatory cytokine increase, such as the macrophage migration inhibitory factor MIF. Depending on conditions, MIF may exert both beneficial and deleterious effects on the myocardium. Therefore, we tested whether pharmacological inhibition of MIF prevented or worsened metabolic syndrome-induced myocardial dysfunction. C57BL/6J mice were fed for ten weeks with 60% fat-enriched diet (HFD) or normal diet (ND). MIF inhibition was obtained by injecting mice twice a week with ISO-1, for three consecutive weeks. Then, triglycerides, cholesterol, fat mass, glucose intolerance, insulin resistance, ex vivo cardiac contractility, animal energetic substrate utilization assessed by indirect calorimetry and mitochondrial respiration and biogenesis were evaluated. HFD led to fat mass increase, dyslipidemia, glucose intolerance and insulin resistance. ISO-1 did not alter these parameters. However, MIF inhibition was responsible for HFD-induced cardiac dysfunction worsening. Mouse capacity to increase oxygen consumption in response to exercise was reduced in HFD compared to ND, and further diminished in ISO-1-treated HFD group. Mitochondrial respiration was reduced in HFD mice, treated or not with ISO-1. Compared to ND, mitochondrial biogenesis signaling was upregulated in the HFD as demonstrated by mitochondrial DNA amount and PGC-1α expression. However, this increase in biogenesis was blocked by ISO-1 treatment. MIF inhibition achieved by ISO-1 was responsible for a reduction in HFD-induced mitochondrial biogenesis signaling that could explain majored cardiac dysfunction observed in HFD mice treated with MIF inhibitor.
Algerian university libraries and the digital age: new communication behaviors
Purpose – The purpose of this paper is to clarify the digital era and to explain that these changes have given rise to the existence of several communities or consortia in higher education of Algeria in order to bring users closer. Various changes linked to advancement in information technologies have changed work methods and behavior among professionals in the information and communication sciences field. Design/methodology/approach – The paper opted for a survey which was organized into two principal phases. An exploratory phase that consisted of undertaking qualitative interviews and another phase followed by a preliminary survey (pilot study) to prepare for the definitive survey. In this way that the authors chose a sample of a total of 50 questionnaires. The authors succeeded in obtaining a total of 30 respondents, representing a response rate of 60 percent. Findings – The preliminary survey reveals that the Algerian university libraries wish to create a community of exchange and collaborative work between professional colleagues in this new digital age. Research limitations/implications – This study is a beginning of a research on the behaviors of professionals in Algerian university libraries. A national survey is about to be performed in order to analyze more better the new communication behaviors. Practical implications – The paper includes implications for changing the new behavior of professionals in university libraries in order to be adapted in this new digital age that requires us to work in the library without walls. Originality/value – The originality of this paper is to discuss the subject of the digital libraries, the information retrieval and the collaborative work environments and the Semantic Web.
Macrophage Migration Inhibitory Factor Inhibition Is Deleterious for High-Fat Diet-Induced Cardiac Dysfunction. e58718
Aims Development of metabolic syndrome is associated with impaired cardiac performance, mitochondrial dysfunction and pro-inflammatory cytokine increase, such as the macrophage migration inhibitory factor MIF. Depending on conditions, MIF may exert both beneficial and deleterious effects on the myocardium. Therefore, we tested whether pharmacological inhibition of MIF prevented or worsened metabolic syndrome-induced myocardial dysfunction. Methods and Results C57BL/6J mice were fed for ten weeks with 60% fat-enriched diet (HFD) or normal diet (ND). MIF inhibition was obtained by injecting mice twice a week with ISO-1, for three consecutive weeks. Then, triglycerides, cholesterol, fat mass, glucose intolerance, insulin resistance, ex vivo cardiac contractility, animal energetic substrate utilization assessed by indirect calorimetry and mitochondrial respiration and biogenesis were evaluated. HFD led to fat mass increase, dyslipidemia, glucose intolerance and insulin resistance. ISO-1 did not alter these parameters. However, MIF inhibition was responsible for HFD-induced cardiac dysfunction worsening. Mouse capacity to increase oxygen consumption in response to exercise was reduced in HFD compared to ND, and further diminished in ISO-1-treated HFD group. Mitochondrial respiration was reduced in HFD mice, treated or not with ISO-1. Compared to ND, mitochondrial biogenesis signaling was upregulated in the HFD as demonstrated by mitochondrial DNA amount and PGC-1 alpha expression. However, this increase in biogenesis was blocked by ISO-1 treatment. Conclusion MIF inhibition achieved by ISO-1 was responsible for a reduction in HFD-induced mitochondrial biogenesis signaling that could explain majored cardiac dysfunction observed in HFD mice treated with MIF inhibitor.
Ambrisentan and Tadalafil Up-front Combination Therapy in Scleroderma-associated Pulmonary Arterial Hypertension
Scleroderma-associated pulmonary arterial hypertension (SSc-PAH) is a rare disease characterized by a very dismal response to therapy and poor survival. We assessed the effects of up-front combination PAH therapy in patients with SSc-PAH. In this prospective, multicenter, open-label trial, 24 treatment-naive patients with SSc-PAH received ambrisentan 10 mg and tadalafil 40 mg daily for 36 weeks. Functional, hemodynamic, and imaging (cardiac magnetic resonance imaging and echocardiography) assessments at baseline and 36 weeks included changes in right ventricular (RV) mass and pulmonary vascular resistance as co-primary endpoints and stroke volume/pulmonary pulse pressure ratio, tricuspid annular plane systolic excursion, 6-minute walk distance, and N-terminal pro-brain natriuretic peptide as secondary endpoints. At 36 weeks, we found that treatment had resulted in significant reductions in median (interquartile range [IQR]) RV mass (28.0 g [IQR, 20.6-32.9] vs. 32.5 g [IQR, 23.2-41.4]; P < 0.05) and median pulmonary vascular resistance (3.1 Wood units [IQR, 2.0-5.7] vs. 6.9 Wood units [IQR, 4.0-12.9]; P < 0.0001) and in improvements in median stroke volume/pulmonary pulse pressure ratio (2.6 ml/mm Hg [IQR, 1.8-3.5] vs. 1.4 ml/mm Hg [IQR 8.9-2.4]; P < 0.0001) and mean ( ± SD) tricuspid annular plane systolic excursion (2.2 ± 0.12 cm vs. 1.65 ± 0.11 cm; P < 0.0001), 6-minute walk distance (395 ± 99 m vs. 343 ± 131 m; P = 0.001), and serum N-terminal pro-brain natriuretic peptide (647 ± 1,127 pg/ml vs. 1,578 ± 2,647 pg/ml; P < 0.05). Up-front combination therapy with ambrisentan and tadalafil significantly improved hemodynamics, RV structure and function, and functional status in treatment-naive patients with SSc-PAH and may represent a very effective therapy for this patient population. In addition, we identified novel hemodynamic and imaging biomarkers that could have potential value in future clinical trials. Clinical trial registered with www.clinicaltrials.gov (NCT01042158).