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Nanoplásticos de poliestireno como moduladores do eixo microbiota-intestino-cérebro: implicações na disbiose e no estresse oxidativo em camundongas em diferentes fases do desenvolvimento

Thu, 01 Jan 2026 00:00:00 GMT

Título: Nanoplásticos de poliestireno como moduladores do eixo microbiota-intestino-cérebro: implicações na disbiose e no estresse oxidativo em camundongas em diferentes fases do desenvolvimento Autor(es): Lima, Júlia Grombone de Vasconcellos Abstract: The environmental dissemination of micro- and nanoplastics (MNPs) has raised growing concerns regarding their impact on human health and the integrity of the microbiota-gut-brain axis. This study evaluated the effects of repeated oral exposure to polystyrene nanoplastics (100 nm, 40 mg/kg) over 21 days in late young (n=16) and pre-pubertal (n=15) female Swiss mice. Two cohorts underwent a battery of behavioral tests, including the Open Field Test and Forced Swim Test. Following euthanasia, fecal samples were collected for microbiota analysis via qPCR, and brain tissues—specifically the hippocampus (HP), prefrontal cortex (PFC), and striatum (STR)—were harvested to quantify biomarkers of oxidative and nitrosative stress. The results demonstrated that while there were no alterations in global locomotion or classical anxiety- and depression-like behaviors, exposed pre-pubertal animals showed a significant increase in peripheral rearing ($p=0.0252$) and grooming ($p<0.05$), indicating an age-dependent selective modulation of exploratory and emotional behavior. Regarding the gut microbiota, no changes were detected in the isolated abundances of Firmicutes or Bacteroidetes; however, a reduction in the Firmicutes/Bacteroidetes ratio was observed in both exposed groups ($p=0.0101$), suggesting the presence of subtle dysbiosis. Distinct vulnerabilities to nitrosative stress were observed according to the life stage: pre-pubertal animals exhibited a robust increase in nitrite levels (p=0.0017), whereas late youngs displayed a compensatory increase in reduced glutathione (GSH) (p=0.0136) within the hippocampus. In conclusion, repeated exposure to nanoplastics promotes low magnitude yet selective effects, with greater neurobehavioral and nitrosative vulnerability during the pre-pubertal stage. These findings provide evidence supporting the involvement of the microbiota-gut-brain axis in the toxicity of these emerging pollutants. Tipo: Dissertação

Investigação do papel das nets (armadilhas extracelulares de neutrófilos) na imunopatogênese da chikungunya

Wed, 01 Jan 2025 00:00:00 GMT

Título: Investigação do papel das nets (armadilhas extracelulares de neutrófilos) na imunopatogênese da chikungunya Autor(es): Leal, Alberto Rubens Siqueira Nogueira Abstract: Neutrophil extracellular traps (NETs) are web-like structures composed of DNA, histones, and antimicrobial proteins released by neutrophils as part of the innate immune response. Although NETs have been extensively studied in bacterial infections, their role in viral diseases, such as Chikungunya virus (CHIKV) infection, remains poorly understood. In viral infections, NETs have an ambiguous role, being able to act as a defense mechanism, but can intensify inflammation and cause tissue damage when released excessively. CHIKV infection causes symptoms such as fever, malaise, rash, myalgia, and especially prolonged arthralgia, which can compromise quality of life. Although it is usually self-limiting, it can lead to death in at-risk groups, such as infants, the elderly, and people with comorbidities. The scarcity of studies on the role of NETs in CHIKV infection compromises the understanding of host defense mechanisms and limits the advancement of more effective therapeutic and diagnostic strategies. This study investigated the presence of NET markers during CHIKV infection over time in female patients. The study included 40 women with CHIKV infection, evaluated on days D0, D21, D90, D180 and D360, and the control group consisted of 10 healthy women. Tipo: Dissertação

Atividade antibacteriana e antibiofilme de óleorresinas extraídas de duas espécies de copaíba contra Staphylococcus aureus e avaliação da toxicidade

Mon, 01 Jan 2024 00:00:00 GMT

Título: Atividade antibacteriana e antibiofilme de óleorresinas extraídas de duas espécies de copaíba contra Staphylococcus aureus e avaliação da toxicidade Autor(es): Farias, Livia Pontes Abstract: Healthcare-associated infections (HAIs) affect patients under medical care during or after hospital admission, and are associated with numerous deaths annually, directly impacting global public health. This problem is exacerbated by the presence of strains exhibiting antimicrobial resistance, potentially leading to the ineffectiveness of antibiotic therapies. In this context, Staphylococcus aureus is a pathogen of great importance due to its frequent association with HAIs. The genus Copaifera, used in folk medicine due to its biological properties, stands out for its oleoresin production, with various pharmacological effects reported in the literature. Therefore, this study aimed to analyze the antimicrobial and antibiofilm activity of oleoresins extracted from C. arenicola (OCa) and C. langsdorffii (OCl) against S. aureus strains, as well as to evaluate their toxicity against cell lines (L929 and HaCaT) and Artemia salina. Regarding the results, both oleoresins showed Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values between 125 and 500 μg/mL. For the non-volatile fractions of both species, the values were 31.25 to 62.5 μg/mL for MIC and 31.25 to 125 μg/mL for MBC. For the major compounds, the concentrations ranged from 15.625 to 125 μg/mL for both MIC and MBC. The oleoresins also significantly inhibited biofilm formation, with reductions in viable cells ranging from 1 to 8.33 logs, a decline in biomass between 84.6 and 100%, and a decrease in metabolic activity between 67.80 and 100%. In pre-formed biofilms, reductions ranged from 0.71 to 2.71 logs of viable cells; decreases between 56.77% and 86.58% in total biomass; and from 17.77% to 92.62% in metabolic activity. Regarding Scanning Electron Microscopy, a reduction in cell quantity and extracellular matrix was observed, in addition to altered morphology after treatment with oleoresins in the CIM. In the cell viability assay, for both cell lines, the oleoresins showed cytotoxicity starting at a concentration of 250 μg/mL. Regarding A. salina, OCa showed a toxic effect starting at a concentration of 125 μg/mL, and OCl at 250 μg/mL. In light of the above, both oleoresins showed antibacterial and antibiofilm activity against the tested S. aureus strains, and most did not exhibit toxicity at concentrations lower than 250 μg/mL for the cell lines and A. salina. Thus, both oleoresins have promising potential against infections and biofilm formation associated with S. aureus Tipo: Dissertação

Avaliação in vitro da atividade antimicrobiana do Haloperidol em células planctônicas e biofilme de Candida spp. sensível e resistentes ao Fluconazol: determinação do possível mecanismo de ação

Thu, 01 Jan 2026 00:00:00 GMT

Título: Avaliação in vitro da atividade antimicrobiana do Haloperidol em células planctônicas e biofilme de Candida spp. sensível e resistentes ao Fluconazol: determinação do possível mecanismo de ação Autor(es): Oliveira, Leilson Carvalho de Abstract: Fungal infections are particularly noteworthy due to their high morbidity and mortality rates. Estimates suggest that 1 billion individuals may have or live with some type of fungal infection, which is estimated to cause 3.8 to 4 million deaths annually. Candidiasis is the most prevalent opportunistic fungal infection worldwide, caused by yeasts of the genus Candida and exhibiting a high prevalence of clinical isolates resistant to conventional antifungals, making the development of new therapies paramount. In this context, drug repositioning is a strategy that aims to utilize medications already available on the market for purposes different from their initial use, for which haloperidol, a first-generation antipsychotic, has demonstrated potential in the antimicrobial field. From this perspective, the present study aims to evaluate the activity of haloperidol, alone and in combination with classic antifungals, against fluconazole-sensitive and fluconazole-resistant clinical strains of Candida spp., and the possible mechanisms associated with its antifungal action. Broth microdilution tests were performed to determine the Minimum Inhibitory Concentration (MIC), as indicated in the Clinical & Laboratory Standards Institute document M27-A3, for haloperidol and antifungals, along with checkerboard assays and the fractional inhibitory concentration index, flow cytometry, DNA damage assessment by comet assay, assays of formed and forming biofilms, and biofilm assessment by SEM. The results showed MICs of haloperidol ranging from 26.67 to 256 μg/mL. Regarding drug interaction assays, synergistic interactions were found between haloperidol and azoles, fluconazole and itraconazole, respectively, and 12.5% synergism with amphotericin B. The results also revealed that haloperidol induces apoptotic processes in C. albicans and C. auris species, causing DNA damage and methylation and inducing the expression of genes related to oxidative stress, contributing to homeostatic dysregulation, causing severe damage and inducing cell death. Biofilm assays showed a reduction in the viability of the formed biofilm in all species tested, ranging from 34.91% to 51.30% at the MIC concentration of the strains. Similar behavior was observed in the forming biofilm, where the reduction in viability ranged from 38.99% to 51.32%. Thus, haloperidol has great potential for antifungal action and stands out as a promising therapeutic alternative that needs further scientific investigation for future uses with anti-Candida action Tipo: Dissertação