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712 result(s) for "Sousa, Sandra"
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“Mortu Nega”: A Decolonial Film or a Film about Decolonization?
While discourse surrounding decolonization is not new, in recent years it has gained significant momentum with many advocating for its implementation as a means to address historical injustices. However, Olúfẹ́mi Táíwò’s thought-provoking book, coupled with the movie “Mortu Nega”, invites us to critically examine the concept of decolonization. This article aims to present an argument that challenges decolonization narratives by exploring the potential limitations and unintended consequences of embracing decolonization as an absolute solution for humanitarian issues in African societies. To accomplish this, I will begin by providing historical context on Guinea-Bissau, the former Portuguese colony that serves as the focal point of the film. Furthermore, this article will provide a comprehensive description of Flora Gomes’ film, followed by a discussion addressing the trope of decolonization theory. I will use the persistent lack of women’s emancipation and their ongoing struggle for genuine liberation and gender justice in Guinea-Bissau as an example of the need, following Táíwò’s thought, to rethink the uses of decolonization as a tool for analyzing Africa’s issues.
Mechanisms protecting host cells against bacterial pore-forming toxins
Pore-forming toxins (PFTs) are key virulence determinants produced and secreted by a variety of human bacterial pathogens. They disrupt the plasma membrane (PM) by generating stable protein pores, which allow uncontrolled exchanges between the extracellular and intracellular milieus, dramatically disturbing cellular homeostasis. In recent years, many advances were made regarding the characterization of conserved repair mechanisms that allow eukaryotic cells to recover from mechanical disruption of the PM membrane. However, the specificities of the cell recovery pathways that protect host cells against PFT-induced damage remain remarkably elusive. During bacterial infections, the coordinated action of such cell recovery processes defines the outcome of infected cells and is, thus, critical for our understanding of bacterial pathogenesis. Here, we review the cellular pathways reported to be involved in the response to bacterial PFTs and discuss their impact in single-cell recovery and infection.
Non-Muscle Myosin 2A (NM2A): Structure, Regulation and Function
Non-muscle myosin 2A (NM2A) is a motor cytoskeletal enzyme with crucial importance from the early stages of development until adulthood. Due to its capacity to convert chemical energy into force, NM2A powers the contraction of the actomyosin cytoskeleton, required for proper cell division, adhesion and migration, among other cellular functions. Although NM2A has been extensively studied, new findings revealed that a lot remains to be discovered concerning its spatiotemporal regulation in the intracellular environment. In recent years, new functions were attributed to NM2A and its activity was associated to a plethora of illnesses, including neurological disorders and infectious diseases. Here, we provide a concise overview on the current knowledge regarding the structure, the function and the regulation of NM2A. In addition, we recapitulate NM2A-associated diseases and discuss its potential as a therapeutic target.
The Yin and Yang of Pneumolysin During Pneumococcal Infection
Pneumolysin (PLY) is a pore-forming toxin produced by the human pathobiont Streptococcus pneumoniae , the major cause of pneumonia worldwide. PLY, a key pneumococcal virulence factor, can form transmembrane pores in host cells, disrupting plasma membrane integrity and deregulating cellular homeostasis. At lytic concentrations, PLY causes cell death. At sub-lytic concentrations, PLY triggers host cell survival pathways that cooperate to reseal the damaged plasma membrane and restore cell homeostasis. While PLY is generally considered a pivotal factor promoting S. pneumoniae colonization and survival, it is also a powerful trigger of the innate and adaptive host immune response against bacterial infection. The dichotomy of PLY as both a key bacterial virulence factor and a trigger for host immune modulation allows the toxin to display both “Yin” and “Yang” properties during infection, promoting disease by membrane perforation and activating inflammatory pathways, while also mitigating damage by triggering host cell repair and initiating anti-inflammatory responses. Due to its cytolytic activity and diverse immunomodulatory properties, PLY is integral to every stage of S. pneumoniae pathogenesis and may tip the balance towards either the pathogen or the host depending on the context of infection.
The Nigerian Diaspora in the United States and Afropolitanism in Sarah Ladipo Manyika's Like a Mule Bringing Ice Cream to the Sun
This essay explores Sarah Ladipo Manyika's Like a Mule Bringing Ice Cream to the Sun (2016), one of the most innovative novels of the Nigerian U.S. diaspora, from the perspective of \"Afropolitanism.\" Occupying a unique place within African writing and African diasporic writing, the novel does not conform to the traditional understanding of Afropolitanism as the celebration of cultural hybridity and transnationalism. Insofar as its portrayals focus on the individual identities and lives of its African and other non-Western characters and their families, the novel further departs from the conventions of earlier Afropolitan narratives, which tendentially center the whole national or racial community. Because Like a Mule Bringing Ice Cream to the Sun rejects the kind of caricature that passes for life in many works of African diasporic literature, it avoids the Afro-pessimism of previous Afropolitan novels, in which the transnational movement of characters occurs as a result of precarious conditions in the home countries, and which forms part of the search for a dream that could be fulfilled by the modernity and the advancements of technology to be found in the host western country. Instead, Manyika's novel asks readers to dissect meanings between the lines and peel off dense layers of signification. The narrative achieves this nuanced communication of Afropolitanism through its main character, Morayo Da Silva, whose representation extends the cultural politics of Afropolitanism to include subjective politics in the analysis of how we exist in the world. In this way, Like a Mule Bringing Ice Cream to the Sun highlights Morayo's affirmation of the value of diasporic life over and against the ironic posture of black self-negation that can result from the diasporic experience.
Improved Skin Barrier Function Along with Hydration Benefits of Viola yedoensis Extract, Aesculin, and Schaftoside and LC-HRMS/MS Dereplication of Its Bio-Active Components
The skin hydration level is a key factor that influences the physical and mechanical properties of the skin. The stratum corneum (SC), the outermost layer of the epidermis, is responsible for the skin’s barrier function. In this study, we investigated the role of a unique composition of Viola yedoensis extract for its ability to activate CD44, a cell-surface receptor of hyaluronic acid, and aquaporin-3, a water-transporting protein, in human keratinocytes (HaCaT). An ELISA assay evaluating the protein expression levels of CD44, aquaporin-3 (AQP3), filaggrin, and keratin-10 revealed that V. yedoensis extract upregulated the levels of CD44 and AQP3 by 15% and 78%, respectively. Additionally, V. yedoensis extract demonstrated a comparative effect on water vapor flux in TEWL and lipid perturbation in DSC versus the reference, glycerin. In light of this new biological efficacy, a detailed phytochemical characterization was undertaken using an integrated LC-HRMS/MS-based metabolomics approach, which provided further insights on the chemistry of V. yedoensis. This led to the identification of 29 secondary metabolites, 14 of which are reported here for the first time, including esculetin, aesculin, apigenin and kaempferol C-glycosides, megastigmane glycosides, roseoside, platanionoside B, and an eriojaposide B isomer, along with the rare, calenduloside F and esculetin diglucoside, which are reported for the first time from the genus, Viola. Notably, two active components identified in the V. yedoensis extract, namely, aesculin and schaftoside, showed an upregulation of the protein expression of CD44 in HaCaT cells by 123% and 193% within 24 h of treatment, respectively, while aesculin increased AQP3 levels by 46%. Aesculin and schaftoside also significantly upregulated the expression of K-10 levels by 299% and 116%, which was considerably higher than sodium hyaluronate, the positive control. The rationale used to characterize the new structures is outlined along with the related biosynthetic pathways envisioned to generate roseoside and Eriojaposide B. These findings provide new molecular insights to deepen the understanding of how V. yedoensis extract, along with the biomarkers aesculin and schaftoside, restores the skin barrier and skin hydration benefits.
Molecular properties of the RmlT wall teichoic acid rhamnosyltransferase that modulates virulence in Listeria monocytogenes
Wall teichoic acids (WTAs) from the major Gram-positive foodborne pathogen Listeria monocytogenes are peptidoglycan-associated glycopolymers decorated by monosaccharides that, while not essential for bacterial growth, are required for bacterial virulence and resistance to antimicrobials. Here we report the structure and function of a bacterial WTAs rhamnosyltransferase, RmlT, strictly required for L. monocytogenes WTAs rhamnosylation. In particular, we demonstrated that RmlT transfers rhamnose from dTDP-L-rhamnose to naked WTAs, and that specificity towards TDP-rhamnose is not determined by its binding affinity. Structures of RmlT with and without its substrates showed that this enzyme is a dimer, revealed the residues responsible for interaction with the substrates and that the catalytic residue pre-orients the acceptor substrate towards the nucleophilic attack to the sugar. Additionally, the structures provided indications for two potential interaction pathways for the long WTAs on the surface of RmlT. Finally, we confirmed that WTAs glycosyltransferases are promising targets for next-generation strategies against Gram-positive pathogens by showing that inactivation of the RmlT catalytic activity results in a decreased infection in vivo. Wall teichoic acids glycosylation is critical for bacterial virulence and antimicrobial resistance. Here, the authors characterized RmlT, a critical rhamnosyltransferase in Listeria monocytogenes , revealing its structure, catalytic mechanism, and potential as a target for anti-virulence therapies.
The Effects of Prenatal Diet on Calf Performance and Perspectives for Fetal Programming Studies: A Meta-Analytical Investigation
This meta-analysis aimed to identify knowledge gaps in the scientific literature on future fetal-programming studies and to investigate the factors that determine the performance of beef cows and their offspring. A dataset composed of 35 publications was used. The prenatal diet, body weight (BW), average daily gain (ADG) during pregnancy, and calf sex were elicited as possible modulators of the beef cows and their offspring performance. Then, the correlations between these variables and the outcomes of interest were investigated. A mixed multiple linear regression procedure was used to evaluate the relationships between the responses and all the possible explanatory variables. A knowledge gap was observed in studies focused on zebu animals, with respect to the offspring sex and the consequences of prenatal nutrition in early pregnancy. The absence of studies considering the possible effects promoted by the interactions between the different stressors’ sources during pregnancy was also detected. A regression analysis showed that prenatal diets with higher levels of protein improved the ADG of pregnant beef cows and that heavier cows give birth to heavier calves. Variations in the BW at weaning were related to the BW at birth and calf sex. Therefore, this research reinforces the importance of monitoring the prenatal nutrition of beef cows.
Impact of a Hybrid Prevention Program for High School Students on Prescription Drug Misuse Outcomes
Prescription drug misuse among youth is a significant public health problem that can lead to negative consequences, including addiction and overdose deaths. This study examined the effectiveness of an evidence-based hybrid approach in preventing prescription drug misuse outcomes in high school students. The prevention program used a combination of e-learning modules and classroom activities to enhance social and personal competence skills and refusal skills to deter prescription drug misuse and other types of substance misuse. Findings indicated that prescription sedative misuse was lower among students who received the hybrid prevention program compared to students in the control group. Perceived risk of using prescription sedatives, painkillers, and stimulants prescribed for someone else was higher in the intervention group relative to the control group students. These findings indicate that a comprehensive, universal school-based hybrid prevention program can produce positive impacts on sedative use and perceived risks of prescription drug misuse.
L-Rhamnosylation of Listeria monocytogenes Wall Teichoic Acids Promotes Resistance to Antimicrobial Peptides by Delaying Interaction with the Membrane
Listeria monocytogenes is an opportunistic Gram-positive bacterial pathogen responsible for listeriosis, a human foodborne disease. Its cell wall is densely decorated with wall teichoic acids (WTAs), a class of anionic glycopolymers that play key roles in bacterial physiology, including protection against the activity of antimicrobial peptides (AMPs). In other Gram-positive pathogens, WTA modification by amine-containing groups such as D-alanine was largely correlated with resistance to AMPs. However, in L. monocytogenes, where WTA modification is achieved solely via glycosylation, WTA-associated mechanisms of AMP resistance were unknown. Here, we show that the L-rhamnosylation of L. monocytogenes WTAs relies not only on the rmlACBD locus, which encodes the biosynthetic pathway for L-rhamnose, but also on rmlT encoding a putative rhamnosyltransferase. We demonstrate that this WTA tailoring mechanism promotes resistance to AMPs, unveiling a novel link between WTA glycosylation and bacterial resistance to host defense peptides. Using in vitro binding assays, fluorescence-based techniques and electron microscopy, we show that the presence of L-rhamnosylated WTAs at the surface of L. monocytogenes delays the crossing of the cell wall by AMPs and postpones their contact with the listerial membrane. We propose that WTA L-rhamnosylation promotes L. monocytogenes survival by decreasing the cell wall permeability to AMPs, thus hindering their access and detrimental interaction with the plasma membrane. Strikingly, we reveal a key contribution of WTA L-rhamnosylation for L. monocytogenes virulence in a mouse model of infection.