ABCC subfamily vacuolar transporters are involved in Pb (lead) detoxification in Saccharomyces cerevisiae

The present work has as objective to contribute for the elucidation of the mechanism associated with Pb detoxification, using the yeast Saccharomyces cerevisiae as a model organism. The deletion of GTT1 or GTT2 genes, coding for functional glutathione transferases (GST) enzymes in S. cerevisiae, caused an increased susceptibility to high Pb concentrations (5001000 mol L1). These results suggest that the formation of glutathione-Pb conjugate (GS-Pb), dependent of GSTs, is important in Pb detoxification. The involvement of ATP-binding cassette (ABC) vacuolar transporters, belonging to class C subfamily (ABCC) in vacuolar compartmentalization of Pb, was evaluated. For this purpose, mutant strains disrupted in YCF1, VMR1, YBT1 or BPT 1 genes were used. All mutants tested, without vacuolar ABCC transporters, presented an increased sensitivity to 5001000 mol L1 Pb comparative to wild-type strain. Taken together, the obtained results suggest that Pb detoxification, by vacuolar compartmentalization, can occur as a result of the concerted action of GSTs and vacuolar ABCC transporters. Pb is conjugated with glutathione, catalysed by glutathione transferases and followed to the transport of GS-Pb conjugate to the vacuole by ABCC transporters.The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013

The effect of multicultural attitudes and perceived intergroup threat on attitudes towards immigrants in Portugal: a polynomial regression with response surface analysis

Supported by the Intergroup Threat Theory (ITT), this study analyzes the effect of multicultural ideology on attitudes towards immigrants mediated by realistic, symbolic, and zero-sum threats. With a sample of Portuguese participants (N = 404)), polynomial regression analysis with response surface methodology was used to test the effects of multicultural attitude (MA) and perceived intergroup threat (PIT) on attitudes towards immigrants (ATI). This study also tested a model in which positive MA leads to a lower PIT, and consequently to more favorable ATI. Four hypotheses were proposed; all of which were confirmed. The results further showed that the direction of discrepancy between MA and PIT can provide a more comprehensive understanding of the complex role of multicultural ideology in predicting ATI. Findings, limitations, and directions for future research are discussed.info:eu-repo/semantics/publishedVersio

Electrospraying of primary chondrocytes for cartilage repair

Electrospun scaffolds have long been used for cartilage repair, due to the topographic similarity between the electrospun fibers and the collagen fibers of the extracellular matrix (ECM) in the native cartilage. Still, while their nanotophography can be beneficial for the cell proliferative and spreading behavior, it greatly reduces the inter-fiber pore size, hindering cell migration and relegating tissue formation to the surface of the scaffold [1]. A possible solution for this structura l limitation would be the direct incorporation of cells into the fibers during electrospinning of the fibrous scaffold, overcoming the challenges of cell infiltration into small pore sizes by literally surrounding cells with the fiber matrix as it is produced [1]. This can be achieved using cell electrospraying, a concept first introduced in 2005 by Jayasinghe, enables the deposition of living cells onto specific targets by exposing the cell suspension to an external high intensity electric field [2]. Cell exposure to the electric field, as well as the shear stress of passing through the cell electrospraying apparatus may affect cell viability and function, so several types of cells have been electrosprayed, and no significant influence was observed on a genetic, genomic and physiological level [4]. In fact, our previous work has demonstrated this inertness from a chondrocyte cell line (C28-I2) [5]. Still, these immortalized cells are genetically modified, and might not not accurately replicate the physiological conditions. Primary chondrocytes possess little proliferative ability, showing considerable dedifferentiation from a chondrocyte-like to a more fibroblast-like phenotype over time, particularly if growth factors are not used [5]. In this regard, electrospraying experiments were performed with primary chondrocytes to assess the process influence on chondrocyte viability. After 24 hour-incubation, chondrocyte metabolic activity was measured, and these electrosprayed (E) cells were then slip and cultured in well plates and in threedimensional anisotropic fibrous/porous scaffolds under static and perfused conditions. Non-electrosprayed (NE) cells were considered for comparison. The obtained results confirmed that the behaviour of primary chondrocytes upon electric field exposure was significantly different from that obtained for the chondrocyte cell line, which can be attributed to the lower recovery ability of these cells. Nonetheless, an increasing proliferation rate was observed over time. The proliferation performance of NE and E primary chondrocytes on 3D environment followed a similar trend, with E primary chondrocytes possessing a significantly lower viability than the NE primary chondrocytes. The application of perfused conditions to the E chondrocyte-seeded scaffolds greatly increased the chondrocyte viability to values similar to the ones obtained for NE chondrocyte-seeded scaffolds. Even though the electrosprayed primary chondrocytes suffered a substantial proliferative delay, they were able to recover, particularly under perfused conditions, suggesting that these conditions should be implemented after the electrospraying process, so that this technology might become an effective approach to uniformly incorporate primary chondrocytes into electrospun scaffolds.publishe

Fabrication of electrospun scaffolds with cell laden hydrogel for cartilage tissue engineering

Tissue engineering strategies create artificial substitutes for the regeneration of damaged tissues, beginning with the fabrication of scaffolds moving then to cell incorporation onto those scaffolds and subsequent tissue growth in vitro. Cell seeding techniques, unfortunately, are usually ineffective to develop scaffolds with homogenous cell distribution, resulting in non-functional tissue formation [1]. With electrospun scaffolds, cell incorporation becomes even more challenging. Electrospun scaffolds are a very tightly packed layer of fibers with small pores, that makes difficult the migration of cells onto the scaffolds, as well as, the diffusion of nutrients and wastes. To overcome this drawback, the direct incorporation of cells, using electrospraying technique, onto the scaffolds during the electrospinning process has been reported. Cell electrospraying is a jet-based technique that allows the spray of living cells onto the materials by applying an electric charge in a cellular suspension [2]. Several studies have proved that cells can survive and proliferate after electrospraying process [3], [4]. Still, previous work has shown that while uniformly distributed cell-laden scaffolds can be fabricated using this technique, some issues remain. Cell desiccation on top of the fibers due to longer duration of the experiment and inadequate cell environment – low temperature and CO2 concentration – and solvent toxicity are the main limitations for the optimal efficiency of cell electrospray process onto electrospun fibers. In this regard, in this work, the production of electrospun scaffolds was combined with the electrospray of chondrocyte laden hydrogel creating a shield/protection around the cells during and after the electrospray process, preventing its dehydration. For that, a polymeric solution of polycaprolactone (PCL) and gelatin was electrospun alternately with a chondrocyte-laden sodium alginate hydrogel electrospray. Sodium alginate is a natural polymer widely used in biomedical engineering due to its biocompatibility, biodegradability and ability to form hydrogels [5]. The prepared scaffolds were then cultured for 7 days and the respective cell viability assessed. The percentage of viability was calculated as a ratio of the metabolic activity of the electrosprayed chondrocytes and the metabolic activity of chondrocytes that did not underwent any process. The chondrocyte distribution was also evaluated. On the first day of culture, the results showed that the cellular viability was higher than the one previous reported, demonstrating that the alginate hydrogel allowed the cells to survive and helps in its attachment. After 7 days of culture, cells continue alive with considerable viability increasing. It was also shown that it was possible to incorporate cells homogenously distributed by electrospraying process using the chondrocyte laden hydrogel. These results emphasize the potential value that the hydrogels can have on the electrospraying process with the electrospun scaffolds.publishe

Bio-electrospraying assessment toward in situ chondrocyte-laden electrospun scaffold fabrication

Electrospinning has been widely used to fabricate fibrous scaffolds for cartilage tissue engineering, but their small pores severely restrict cell infiltration, resulting in an uneven distribution of cells across the scaffold, particularly in three-dimensional designs. If bio-electrospraying is applied, direct chondrocyte incorporation into the fibres during electrospinning may be a solution. However, before this approach can be effectively employed, it is critical to identify whether chondrocytes are adversely affected. Several electrospraying operating settings were tested to determine their effect on the survival and function of an immortalized human chondrocyte cell line. These chondrocytes survived through an electric field formed by low needle-to-collector distances and low voltage. No differences in chondrocyte viability, morphology, gene expression, or proliferation were found. Preliminary data of the combination of electrospraying and polymer electrospinning disclosed that chondrocyte integration was feasible using an alternated approach. The overall increase in chondrocyte viability over time indicated that the embedded cells retained their proliferative capacity. Besides the cell line, primary chondrocytes were also electrosprayed under the previously optimized operational conditions, revealing the higher sensitivity degree of these cells. Still, their post-electrosprayed viability remained considerably high. The data reported here further suggest that bio-electrospraying under the optimal operational conditions might be a promising alternative to the existent cell seeding techniques, promoting not only cells safe delivery to the scaffold, but also the development of cellularized cartilage tissue constructs.publishe

a systematic review

The release of modified mosquitoes to suppress/replace vectors constitutes a promising tool for vector control and disease prevention. Evidence regarding these innovative modification techniques is scarce and disperse. This work conducted a systematic review, gathering and analysing research articles from PubMed and Biblioteca Virtual em Saúde databases whose results report efficacy and non-target effects of using modified insects for disease prevention, until 2016. More than 1500 publications were screened and 349 were analysed. Only 12/3.4% articles reported field-based evidence and 41/11.7% covered modification strategies’ post-release efficacy. Variability in the effective results (90/25.7%) questioned its reproducibility in different settings. We also found publications reporting reversal outcomes 38/10.9%, (e.g. post-release increase of vector population). Ecological effects were also reported, such as horizontal transfer events (54/15.5%), and worsening pathogenesis induced by natural wolbachia (10/2.9%). Present work revealed promising outcomes of modifying strategies. However, it also revealed a need for field-based evidence mainly regarding epidemiologic and long-term impact. It pointed out some eventual irreversible and important effects that must not be ignored when considering open-field releases, and that may constitute constraints to generate the missing field evidence. Present work constitutes a baseline of knowledge, offering also a methodological approach that may facilitate future updates.publishersversionpublishe

Anxiety, Depression and Academic Performance: A Study Amongst Portuguese Medical Students Versus Non-Medical Students

Introduction: The aim of the study is to assess the prevalence of anxiety and depressive symptoms in Portuguese medical students compared to students of other faculties, and the possible impact those symptoms have on academic performance. Material and Methods: A cross-sectional study was conducted in a sample of 750 students: 512 medical students and 238 nonmedical students. All students anonymously completed a socio-demographic survey and the Hospital Anxiety and Depression Scale (HADS). Statistical analysis was performed using the chi-square test, Mann-Whitney test, Spearman correlation coefficient or Kruskal-Wallis test. Results: We found a prevalence of 21.5% (n = 161) for anxiety symptoms and 3.7% (n = 28) for depressive symptoms. Being a medical student was more significantly associated with symptoms of anxiety (p = 0.034) compared with other students. Depressive symptoms were slightly associated with poor academic performance (p < 0.01). A percentage of 59.6% (n = 96) of students with anxiety symptoms and 46.4% (n = 13) of students with depressive symptoms did not seek medical or psychological care at that time. Discussion: Medical students in this sample seem to have more symptoms of anxiety, possibly explained by a higher number of female students in that sample. Depressive symptoms could be associated with poor academic performance in both groups, but an evident correlation was not established. Conclusion: Considering the high levels of anxiety symptoms, the possible impact of depressive symptoms in academic performance and the lack of psychiatric or psychological follow-up reported in this study, it is urgent to develop adequate means of support to improve students’ well-being and mental health

URBSOIL-LISBON-Geoquímica dos solos urbanos de Lisboa: caracterização e cartografia, suporte para futuros estudos de saúde humana: resultados preliminares

A Geologia, e em especial a Geoquímica em ambiente urbano, têm-se revelado ferramentas essenciais não só no estudo dos materiais naturais neste ambiente, como na ligação entre a Geologia e a acção antrópica. Este estudo, com uma metodologia que usa vários meios de amostragem, pretende avaliar quais os elementos químicos que podem intervir num contexto de interacção em que as crianças são tomadas como alvo principal. Os primeiros resultados sobre concentrações de elementos químicos para os solos urbanos de Lisboa apontam para uma exposição esparsa na cidade de alguns dos elementos químicos inorgânicos, mas havendo por vezes um zonamento por tipologia de local ou de elemento químico. Foram definidos quatro grupos de pontos de amostragem consoante o tipo de uso, e escolhidos para uma análise mais próxima alguns elementos considerados tendencialmente de input antrópico e que se relacionam com a saúde humana.