Publications by authors named "Haroldo Cesar de Oliveira"

Background: Candida auris has been identified by the World Health Organization as a critical pathogen due to its invasive nature, resistance to multiple drugs, and high mortality rates in hospital outbreaks. This fungus can persist on surfaces and human skin for extended periods, complicating infection control efforts. The need for effective disinfection strategies is urgent, as current disinfectants are often ineffective against C.

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Considering the toxicity of conventional therapeutic approaches and the importance of precise mechanistic targets, it is important to explore signaling pathways implicated in fungal pathobiology. Moreover, treatment of paracoccidioidomycosis, a systemic mycosis caused by a dimorphic fungus, requires prolonged therapeutic regimens. Among the numerous factors underpinning the establishment of spp.

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In this study, we investigated the influence of fungal extracellular vesicles (EVs) during biofilm formation and morphogenesis in Candida albicans. Using crystal violet staining and scanning electron microscopy (SEM), we demonstrated that C. albicans EVs inhibited biofilm formation .

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is a thermally dimorphic fungus belonging to complex, causative of a systemic, endemic mycosis limited to Latin American countries. Signal transduction pathways related to important aspects as surviving, proliferation according to the biological niches are linked to the fungal pathogenicity in many species, but its elucidation in remains poorly explored. As Drk1, a hybrid histidine kinase, plays regulators functions in other dimorphic fungi species, mainly in dimorphism and virulence, here we investigated its importance in .

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Due to its location, the fungal cell wall is the compartment that allows the interaction with the environment and/or the host, playing an important role during infection as well as in different biological functions such as cell morphology, cell permeability and protection against stress. All these processes involve the activation of signaling pathways within the cell. The cell wall integrity (CWI) pathway is the main route responsible for maintaining the functionality and proper structure of the cell wall.

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Heat shock proteins (Hsps) are among the most widely distributed and evolutionary conserved proteins, acting as essential regulators of diverse constitutive metabolic processes. The Hsp60 of the dimorphic fungal is the major surface adhesin to mammalian macrophages and studies of antibody-mediated protection against  have provided insight into the complexity involving Hsp60. However, nothing is known about the role of Hsp60 regarding biofilms, a mechanism of virulence exhibited by .

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Background: Paracoccidioidomycosis (PCM) is a chronic disease that causes sequelae and requires prolonged treatment; therefore, new therapeutic approaches are necessary. In view of this, three peptides from 14-3-3 protein were selected based on its immunogenicity and therapeutic potential.

Methods: The in vitro antifungal activity and cytotoxicity of the 14-3-3 peptides were evaluated.

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Cryptococcus neoformans is a yeast that mainly affects immunocompromised individuals and causes meningoencephalitis depending on the immune status of the host. The present study aimed to validate the efficacy of selective serotonin reuptake inhibitors, fluoxetine hydrochloride (FLH) and paroxetine hydrochloride (PAH), alone and in combination with amphotericin B (AmB) against C. neoformans.

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Cryptococcus gattii is an etiologic agent of cryptococcosis, a potentially fatal disease that affects humans and animals. The successful infection of mammalian hosts by cryptococcal cells relies on their ability to infect and survive in macrophages. Such phagocytic cells present a hostile environment to intracellular pathogens via the production of reactive nitrogen and oxygen species, as well as low pH and reduced nutrient bioavailability.

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Amphotericin B (AmB) is the antifungal with the strongest fungicidal activity, but its use has several limitations, mainly associated with its toxicity. Although some lipidic and liposomal formulations that present reduced toxicity are available, their price limits their application in developing countries. Flucytosine (5FC) has shown synergistic effect with AmB for treatment of some fungal infections, such as cryptococcosis, but again, its price is a limitation for its use in many regions.

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The genus Paracoccidioides consist of dimorphic fungi geographically limited to the subtropical regions of Latin America, which are responsible for causing deep systemic mycosis in humans. However, the molecular mechanisms by which Paracoccidioides spp. causes the disease remain poorly understood.

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Article Synopsis
  • The antifungal drug options available today are limited, leading to a search for alternative treatments like Decyl gallate (G14), which shows broad-spectrum antifungal activity and fewer side effects.
  • A genetic analysis revealed that G14 targets key processes in fungi, such as N-glycosylation and the unfolded protein response (UPR), which affect fungal cell wall integrity.
  • G14's effectiveness was demonstrated through reduced fungal viability and ability to adhere to human lung cells, suggesting it could play a role in managing inflammation during fungal infections.
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is an emerging fungal pathogen of great concern among the scientific community because it is causing an increasing number of hospital outbreaks of difficult management worldwide. In addition, isolates from this species frequently present reduced susceptibility to azole and echinocandin drugs. For this reason, it is necessary to develop new antifungal strategies to better control the disease caused by this yeast.

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Traditionally, the screening of metabolites in microbial matrices is performed by monocultures. Nonetheless, the absence of biotic and abiotic interactions generally observed in nature still limit the chemical diversity and leads to "poorer" chemical profiles. Nowadays, several methods have been developed to determine the conditions under which cryptic genes are activated, in an attempt to induce these silenced biosynthetic pathways.

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Article Synopsis
  • Ppz Ser/Thr protein phosphatases (PPases) are exclusive to fungi and have potential as antifungal drug targets, particularly in Cryptococcus neoformans (Cn).
  • The study examines the roles of CnPpz1 and two Hal3-like proteins (CnHal3a and CnHal3b), finding that CnHal3b deletion results in reduced virulence and distinct phenotypes from Saccharomyces cerevisiae mutants.
  • CnHal3 proteins interact with both CnPpz1 and ScPpz1 but do not inhibit their phosphatase activity; however, CnHal3b's 3D structure was revealed, enhancing our grasp of the Ppz1-H
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The Paracoccidioides brasiliensis strain downregulated the expression of adhesin Pb14-3-3 (Pb14-3-3 aRNA) was evaluated in a murine model of paracoccidioidomycosis (PCM). Pb14-3-3 aRNA displays attenuated virulence and triggered the formation of fewer granulomas by lowering the fungal burden in the lungs. Additionally, the Pb14-3-3 aRNA showed more elongated yeast cells and less ability to induce pneumocytes apoptosis in vitro.

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Cryptococcus neoformans is an encapsulated pathogenic yeast that can change the size of the cells during infection. In particular, this process can occur by enlarging the size of the capsule without modifying the size of the cell body, or by increasing the diameter of the cell body, which is normally accompanied by an increase of the capsule too. This last process leads to the formation of cells of an abnormal enlarged size denominated titan cells.

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Paracoccidioidomycosis is a systemic fungal infection affecting mainly Latin American countries that is caused by Paracoccidioides brasiliensis and Paracoccidioides lutzii. During the study of fungal pathogenesis, in vivo studies are crucial to understand the overall mechanisms involving the infection as well as to search for new therapeutic treatments and diagnosis. Caenorhabditis elegans is described as an infection model for different fungi species and a well-characterized organism to study the innate immune response.

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Article Synopsis
  • Paracoccidioidomycosis (PCM) is a fungal infection primarily found in Latin America, caused by fungi from the Paracoccidioides genus.
  • The study investigated how the ability of the fungus P. brasiliensis to adhere (stick) to host cells could be regained after being subcultured, with comparisons made between tests in mice and the insect Galleria mellonella.
  • Results showed that using Galleria mellonella was an effective method for reactivating the adhesion capabilities of P. brasiliensis, highlighting its potential use in research.
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Apoptosis is considered an escape mechanism from the host immune system for the fungus Paracoccidioides spp, and it serves as a vehicle for entry into macrophages without stimulating microbicidal activities. Recently, gp43 of P. brasiliensis was demonstrated to be involved in this process.

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Cryptococcosis is an opportunistic fungal infection responsible for high morbidity and mortality in immunocompromised patients. Combination of antifungal substances is a promising way to increase the percentage of successful treatment. Pedalitin (PED) is a natural substance obtained from Pterogyne nitens.

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Paracoccidioides spp., which are temperature-dependent dimorphic fungi, are responsible for the most prevalent human systemic mycosis in Latin America, the paracoccidioidomycosis. The aim of this study was to characterise the involvement of elongation factor Tu (EF-Tu) in Paracoccidioides brasiliensis-host interaction.

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The interaction between the fungal pathogen Paracoccidioides brasiliensis and host cells is usually mediated by specific binding events between adhesins on the fungal surface and receptors on the host extracellular matrix or cell surface. One molecule implicated in the P. brasiliensis-host interaction is the 14-3-3 protein.

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Article Synopsis
  • Paracoccidioidomycosis, a systemic fungal infection endemic to Latin America, is caused by the species Paracoccidioides brasiliensis and P. lutzii.
  • The study compares the virulence of these two species using the Galleria mellonella model, which serves as an ethical alternative to traditional murine models.
  • Findings reveal that while both species cause similar larval deaths and reduce hemocyte counts, P. lutzii exhibits more significant interactions and gene expression related to phagocyte adherence, indicating potential differences in their pathogenicity.
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Background: 14-3-3 proteins comprise a family of eukaryotic multifunctional proteins involved in several cellular processes. The Pb14-3-3 of Paracoccidioides brasiliensis seems to play an important role in the Paracoccidioides-host interaction. Paracoccidioides brasiliensis is an etiological agent of paracoccidioidomycosis, which is a systemic mycosis that is endemic in Latin America.

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