Search Results (9)

Background: Photodynamic therapy (PDT) is a treatment modality that uses light to activate a photosensitizing agent, destroying target cells. The growing awareness of the necessity to reduce or eliminate the use of mammals in research has prompted the search for safer toxicity testing models aligned with the new global guidelines and compliant with the relevant regulations. Objective: The objective of this study was to assess the impact of PDT on alternative models to mammals, including in vitro three-dimensional (3D) cultures and in vivo, in invertebrate animals, utilizing a potent photosensitizer, 2-hydroxychalcone. Methods: Cytotoxicity was assessed in two cellular models: monolayer (2D) and 3D. For this purpose, spheroids of two cell lines, primary dermal fibroblasts (HDFa) and adult human epidermal cell keratinocytes (HaCat), were developed and characterized following criteria on cell viability, shape, diameter, and number of cells. The survival percentages of Caenorhabditis elegans and Galleria mellonella were evaluated at 1 and 7 days, respectively. Results: The findings indicated that all the assessed platforms are appropriate for investigating PDT toxicity. Furthermore, 2-hydroxychalcone demonstrated low toxicity in the absence of light and when mediated by PDT across a range of in vitro (2D and 3D cultures) and in vivo (invertebrate animal models, including G. mellonella and C. elegans) models. Conclusion: There was a strong correlation between the in vitro and in vivo tests, with similar toxicity results, particularly in the 3D models and C. elegans, where the concentration for 50% viability was approximately 100 µg/mL. Full article

Dog behavioural problems are one of the main reasons for dog relinquishment. Studies on how dog behavioural problems affect owner well-being are limited. We review the literature concerning the link between dog behavioural problems and owner well-being. We propose practical solutions to minimize the negative impacts of behavioural problems on human well-being and dog welfare, whilst suggesting future research directions. Twenty-one studies were included in the literature review. These indicate that dog behavioural problems may particularly reduce social interactions, and increase negative emotions of high arousal, such as stress and frustration, caregiver burden and symptoms of both depression and anxiety in their owners. To improve both owner well-being and dog welfare, we suggest targeting three areas: practical behavioural support for the dog–human dyad, social support for owners and psychological support for owners. Considering the lack of research in the field, further studies are needed to better understand the relationship between dog behavioural problems and human well-being, such as how the three areas previously mentioned may affect dog relinquishment and owner well-being. Full article

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 Paracoccidioides spp. infection, the capacity to transition from the mycelial to the yeast form is of pivotal importance. The Drk1 protein of Paracoccidioides brasiliensis likely plays a decisive role in this morphological shift and subsequent virulence. We identified peptides with affinity for the PbDrk1 protein using the phage-display method and assessed the effects of these peptides on P. brasiliensis. The peptides were found to inhibit the phase transition of P. brasiliensis. Furthermore, a substantial proportion of these peptides prevented adhesion to pneumocytes. Although these peptides may not possess inherent antifungal properties, they can augment the effects of certain antifungal agents. Notably, the cell wall architecture of P. brasiliensis appears to be modulated by peptide intervention, resulting in a reduced abundance of glycosylated proteins and lipids. These peptides were also evaluated for their efficacy in a Galleria mellonella model and shown to contribute to enhanced larval survival rates. The role of PbDrk1, which is notably absent in mammals, should be further investigated to improve the understanding of its functional role in P. brasiliensis, which may be helpful for designing novel therapeutic modalities. Full article

This study aimed to characterize a Klebsiella pneumoniae strain (KP411) recovered from the stool samples of poultry (Gallus gallus) in the Brazilian Amazon Region. The whole-genome sequencing of KP411 revealed the presence of an important arsenal of antimicrobial resistance genes to β-lactams (bla_CTX-M-14, bla_TEM-1B, bla_KPC-2, bla_SVH-11), aminoglycosides [aph(3″)- Ib, aph(6)-Id, aph(3′)-Ia], sulfonamides (sul1, sul2), quinolones (oqxAB), fosfomycin (fosA^KP), and macrolides [mph(A)]. Furthermore, our analyses revealed that the KP411 strain belongs to the ST258 clonal lineage, which is one of the main epidemic clones responsible for the dissemination of KPC-2 worldwide. Our data suggest that food-producing animals may act as reservoirs of multidrug-resistant K. pneumoniae belonging to the ST258 clone, and, consequently, contribute to their dissemination to humans and the environment. Full article

While primarily Gram-positive bacteria cause bacterial eye infections, several Gram-negative species also pose eye health risks. Currently, few studies have tried to understand the pathogenic mechanisms involved in E. coli eye infections. Therefore, this study aimed to establish the pathogenic potential of E. coli strains isolated from eye infections. Twenty-two strains isolated between 2005 and 2019 from patients with keratitis or conjunctivitis were included and submitted to traditional polymerase chain reactions (PCR) to define their virulence profile, phylogeny, clonal relationship, and sequence type (ST). Phenotypic assays were employed to determine hemolytic activity, antimicrobial susceptibility, and adhesion to human primary corneal epithelial cells (PCS-700-010). The phylogenetic results indicated that groups B2 and ST131 were the most frequent. Twenty-five virulence genes were found among our strains, with ecp, sitA, fimA, and fyuA being the most prevalent. Two strains presented a hemolytic phenotype, and resistance to ciprofloxacin and ertapenem was found in six strains and one strain, respectively. Regarding adherence, all but one strains adhered in vitro to corneal cells. Our results indicate significant genetic and virulence variation among ocular strains and point to an ocular pathogenic potential related to multiple virulence mechanisms. Full article

Histoplasma capsulatum is a fungus that causes histoplasmosis. The increased evolution of microbial resistance and the adverse effects of current antifungals help new drugs to emerge. In this work, fifty-four nitrofurans and indoles were tested against the H. capsulatum EH-315 strain. Compounds with a minimum inhibitory concentration (MIC₉₀) equal to or lower than 7.81 µg/mL were selected to evaluate their MIC₉₀ on ATCC G217-B strain and their minimum fungicide concentration (MFC) on both strains. The quantification of membrane ergosterol, cell wall integrity, the production of reactive oxygen species, and the induction of death by necrosis–apoptosis was performed to investigate the mechanism of action of compounds 7, 11, and 32. These compounds could reduce the extracted sterol and induce necrotic cell death, similarly to itraconazole. Moreover, 7 and 11 damaged the cell wall, causing flaws in the contour (11), or changing the size and shape of the fungal cell wall (7). Furthermore, 7 and 32 induced reactive oxygen species (ROS) formation higher than 11 and control. Finally, the cytotoxicity was measured in two models of cell culture, i.e., monolayers (cells are flat) and a three-dimensional (3D) model, where they present a spheroidal conformation. Cytotoxicity assays in the 3D model showed a lower toxicity in the compounds than those performed on cell monolayers. Overall, these results suggest that derivatives of nitrofurans and indoles are promising compounds for the treatment of histoplasmosis. Full article

Fungal diseases affect more than 1 billion people worldwide. The constant global changes, the advent of new pandemics, and chronic diseases favor the diffusion of fungal pathogens such as Candida, Cryptococcus, Aspergillus, Trichophyton, Histoplasma capsulatum, and Paracoccidioides brasiliensis. In this work, a series of nitrofuran derivatives were synthesized and tested against different fungal species; most of them showed inhibitory activity, fungicide, and fungistatic profile. The minimal inhibitory concentration (MIC₉₀) values for the most potent compounds range from 0.48 µg/mL against H. capsulatum (compound 11) and P. brasiliensis (compounds 3 and 9) to 0.98 µg/mL against Trichophyton rubrum and T. mentagrophytes (compounds 8, 9, 12, 13 and 8, 12, 13, respectively), and 3.9 µg/mL against Candida and Cryptococcus neoformans strains (compounds 1 and 5, respectively). In addition, all compounds showed low toxicity when tested in vitro on lung cell lines (A549 and MRC-5) and in vivo in Caenorhabditis elegans larvae. Many of them showed high selectivity index values. Thus, these studied nitrofuran derivatives proved to be potent against different fungal species, characterized by low toxicity and high selectivity; for these reasons, they may become promising compounds for the treatment of mycoses. Full article

Cross-sectional comparisons of well-being between dog owners and non-owners commonly generate inconsistent results. Focusing on the uniqueness of the relationship might help address this issue and provide a stronger foundation for dog-related psychotherapeutic interventions. This study aims to evaluate the impact of dog-related activities (e.g., exercising the dog) on owner hedonic well-being, life satisfaction and eudaimonic well-being. It was also hypothesised that psychological closeness to the dog would affect these well-being outcomes. For this study, 1030 dog owners aged over 18 years old answered an online questionnaire about the impact of 15 groups of dog-related activities on their well-being. Ordinal regressions were used to estimate the mean response (and its uncertainty) for each outcome, while conditioning for psychological closeness to the dog and controlling for several key covariates. Tactile interactions and dog playing were significantly more beneficial than other activities for hedonic well-being, and dog training and dog presence for eudaimonic well-being. In contrast, dog health issues and behavioural problems were linked to decrements in these well-being outcomes. Higher psychological closeness to the dog predicted greater improvement in well-being in positive dog-related activities. Our quantitative study validates the general findings of previous qualitative work and lays the groundwork for future longitudinal studies. Full article

We argue that there is currently an under-reporting of the ways in which pain can be associated with problem behavior, which is seriously limiting the recognition of this welfare problem. A review of the caseloads of 100 recent dog cases of several authors indicates that a conservative estimate of around a third of referred cases involve some form of painful condition, and in some instances, the figure may be nearly 80%. The relationship is often complex but always logical. Musculoskeletal but also painful gastro-intestinal and dermatological conditions are commonly recognized as significant to the animal’s problem behavior. The potential importance of clinical abnormalities such as an unusual gait or unexplained behavioral signs should not be dismissed by clinicians in general practice, even when they are common within a given breed. In general, it is argued that clinicians should err on the side of caution when there is a suspicion that a patient could be in pain by carefully evaluating the patient’s response to trial analgesia, even if a specific physical lesion has not been identified. Full article