Antibacterial and resistance-modifying activities of thymoquinone against oral pathogens

<p>Abstract</p> <p>Background</p> <p>The presence of resistant bacteria in the oral cavity can be the major cause of dental antibiotic prophylaxis failure. Multidrug efflux has been described for many organisms, including bacteria and fungi as part of their drugs resistance strategy. The discovery of a new efflux pump inhibitor could extend the useful lifetime of some antibiotics.</p> <p>Methods</p> <p>In this study, the MICs of thymoquinone (TQ), tetracycline and benzalkonium chloride (BC) were determined in absence and in presence of a sub-MIC doses of thymoquinone (1/2 MIC). In addition the 4,6-diamidino-2-phenylindole (DAPI) efflux assay was carried out to determine the effect of TQ on DAPI cells accumulation.</p> <p>Results</p> <p>TQ induced a selective antimicrobial activity. Its synergic effect resulted in at least a 4-fold potentiation of the tested antibiotics and antiseptic. In addition, TQ inhibited the DAPI efflux activity in a concentration-dependent manner. The rate of DAPI accumulation in clinical isolates was enhanced with TQ (0 to 200 μg/ml). There is also a decrease in loss of DAPI from bacteria in the presence of TQ. The concentration causing 50% of DAPI efflux inhibition after 15 minutes was approximately 59 μg/ml for <it>Pseudomonas aeroginosa </it>and 100 μg/ml and <it>Staphylococcus aureus </it>respectively.</p> <p>Conclusions</p> <p>TQ possesses a selective antibacterial activity against oral bacteria. It is therefore suggested that TQ could be used as a source of natural products with resistance-modifying activity. Further investigation is needed to assess their clinical relevance.</p

Crystal structure, Hirshfeld surface analysis, and physicochemical studies of a new Cu(II) complex with 2-amino-4-methylpyrimidine

International audienceThe chemical preparation, crystal structure, magnetic study and spectroscopic characterization of the new Cu(II) complex with the monodentate ligand 2-amino-4-methylpyrimidine [Cu2(CH3COO)4(C5N3H7)2] are reported. The copper atoms are surrounded by one nitrogen atom from one 2-amino-4-methylpyrimidine ligand and four oxygen atoms of CH3COO − groups yielding to a penta-coordination of the metal ion. In the structural arrangement, the amino group and the pyrimidine nitrogen atom of neighboring molecules are linked together through a pair of N-H…N hydrogen bonds forming a 1-D corrugated chain running along the [111] direction wherein the complex molecules are located parallel to the (a, c) plane at z = ½. Intermolecular interactions were investigated by Hirshfeld surfaces and contact enrichment tools. Mulliken charge distribution, molecular electrostatic potential (MEP) maps and HOMO and LUMO energy gaps have been computed. The vibrational absorption bands were identified by infrared spectroscopy. Magnetic properties were also studied to characterize the complex

Desarrollo de un componente Web parametrizable para la visualización de datos científicos

Auxiliar de InvestigaciónEste proyecto se fundamentó en el desarrollo de un componente Web parametrizable para la visualización de datos científicos, el cual permitirá a futuro, con integración de otros componentes, establecer un análisis visual de los datos extraídos, enfocado en la necesidad del usuario.1. GENERALIDADES 2. OBJETIVOS DEL PROYECTO 3. MARCO DE REFERENCIA 4. MARCO CONCEPTUAL 5. METODOLOGÍA 6. DESARROLLO DEL PROYECTO 7. RESULTADOS 8. CONCLUSIONES 9. TRABAJOS FUTUROS 10. BIBLIOGRAFÍA 11. GLOSARIO 12. ANEXOSPregradoIngeniero de Sistema

Antibacterial activity of Thymoquinone, an active principle of Nigella sativa and its potency to prevent bacterial biofilm formation

<p>Abstract</p> <p>Background</p> <p>Thymoquinone is an active principle of <it>Nigella sativa </it>seed known as "Habbah Al-Sauda" in Arabic countries and "Sinouj" in Tunisia. Bacterial biofilms tend to exhibit significant tolerance to antimicrobials drugs during infections.</p> <p>Methods</p> <p>The antibacterial activity of Thymoquinone (TQ) and its biofilm inhibition potencies were investigated on 11 human pathogenic bacteria. The growth and development of the biofilm were assessed using the crystal violet (CV) and the 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) reduction assay.</p> <p>Results</p> <p>TQ exhibited a significant bactericidal activity against the majority of the tested bacteria (MICs values ranged from 8 to 32 μg/ml) especially Gram positive cocci (<it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510). Crystal violet assay demonstrated that the minimum biofilm inhibition concentration (BIC50) was reached with 22 and 60 μg/ml for <it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510 respectively. In addition our data revealed that cells oxidative activity was influenced by TQ supplementation. In the same way, TQ prevented cell adhesion to glass slides surface.</p> <p>Conclusion</p> <p>The ability of TQ to prevent biofilm formation warrants further investigation to explore its use as bioactive substances with antibiofilm potential.</p

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Effets des nanoparticules sur l'angiogenèse et l'organisation astrocytaire, destinés au traitement des gliomes

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

A learning-based model for predicting information diffusion in social networks: Case of Twitter

International audienceDiffusion action is a key behavior of users in online social networks. This action may further propagate to other connections of the users and affect their actions. Recent research has focused on studying the diffusion action of users, particularly, predicting information diffusion in future. However, most of current diffusion models mainly focus on giving general model of diffusion. In this paper, we propose a model of information diffusion prediction which analyzes all factors affecting users' diffusion decision such as user features, link features and crowd-features. In addition, we take into account the presence of multi-topics in the content item. We validate our model by conducting experiments on a snapshot of Twitter containing tweets and retweets involving French media, which demonstrates the interest of our model

Modeling Information Diffusion via Reputation Estimation

International audienceWe tackle the problem of predicting information diffusion in social networks. In this problem, we are given social data and would like to infer the diffusion process in the near future. Although this problem has been extensively studied, the challenge of how to effectively combine user activities, network structures and diffused information in social data remains largely open. In addition, no prior work judged the effect of user reputation on the diffusion process. Availability of such reputation score is really important for a user to decide whether he might share information. In this paper, we first devise a novel method for estimating user reputation. Our approach integrates network structure with user features, link features and the content of items shared by the users, then measures the strength of each of these factors. Based on this estimation approach, we develop a model predicting the tendency of a new information item as well as the number of participants of this diffusion process. We conduct several experiments on a snapshot of Twitter which show that our proposed model outperforms other baselines

Branch and Bound and Dynamic Programming to Minimize the Total Completion Times on a Single Machine with Availability Constraints

International audienceIn this paper we consider the single machine scheduling problem with availability constraints in order to minimize the total completion times of jobs. We propose two exact approaches to solve the problem: a dynamic programming and a branch and bound method. The study of these approaches is carried out in this article and a concluding analysis based on several experimental results allows us to select the most suitable method according to the studied instance