Browsing by Issue Date, starting with "2022-10-01"
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- 3D-printed PLA medical devices: physicochemical changes and biological response after sterilisation treatmentsPublication . Pérez-Davila, Sara; González-Rodríguez, Laura; Lama, Raquel; López-Álvarez, Miriam; Oliveira, Ana Leite; Serra, Julia; Novoa, Beatriz; Figueras, Antonio; González, PíoPolylactic acid (PLA) has become one of the most commonly used polymers in medical devices given its biocompatible, biodegradable and bioabsorbable properties. In addition, due to PLA’s thermoplastic behaviour, these medical devices are now obtained using 3D printing technologies. Once obtained, the 3D-printed PLA devices undergo different sterilisation procedures, which are essential to prevent infections. This work was an in-depth study of the physicochemical changes caused by novel and conventional sterilisation techniques on 3D-printed PLA and their impact on the biological response in terms of toxicity. The 3D-printed PLA physicochemical (XPS, FTIR, DSC, XRD) and mechanical properties as well as the hydrophilic degree were evaluated after sterilisation using saturated steam (SS), low temperature steam with formaldehyde (LTSF), gamma irradiation (GR), hydrogen peroxide gas plasma (HPGP) and CO2 under critical conditions (SCCO). The biological response was tested in vitro (fibroblasts NCTC-929) and in vivo (embryos and larvae wild-type zebrafish Danio rerio). The results indicated that after GR sterilisation, PLA preserved the O:C ratio and the semi-crystalline structure. Significant changes in the polymer surface were found after HPGP, LTSF and SS sterilisations, with a decrease in the O:C ratio. Moreover, the FTIR, DSC and XRD analysis revealed PLA crystallisation after SS sterilisation, with a 52.9% increase in the crystallinity index. This structural change was also reflected in the mechanical properties and wettability. An increase in crystallinity was also observed after SCCO and LTSF sterilisations, although to a lesser extent. Despite these changes, the biological evaluation revealed that none of the techniques were shown to promote the release of toxic compounds or PLA modifications with toxicity effects. GR sterilisation was concluded as the least reactive technique with good perspectives in the biological response, not only at the level of toxicity but at all levels, since the 3D-printed PLA remained almost unaltered.
- The role of NAD metabolism in neuronal differentiationPublication . Neves, Diogo; Goodfellow, Brian J.; Vieira, Sandra I.; Silva, RaquelBackground: Nicotinamide adenine dinucleotide (NAD) metabolism is involved in redox and non-redox reactions that regulate several processes including differentiation of cells of different origins. Here, the role of NAD metabolism in neuronal differentiation, which remains elusive so far, was investigated. Material and methods: A protein-protein interaction network between neurotrophin signaling and NAD metabolic pathways was built. Expression of NAD biosynthetic enzymes in SH-SY5Y cells during retinoic acid (RA)/brain derived neurotrophic factor (BDNF) differentiation, was evaluated. The effects of NAD biosynthetic enzymes QPRT and NAPRT inhibition in neurite outgrowth, cell viability, NAD availability and histone deacetylase (HDAC) activity, were analysed in RA- and BDNF-differentiated cells. Results: Bioinformatics analysis revealed the interaction between NAD biosynthetic enzyme NMNAT1 and NTRK2, a receptor activated by RA/BDNF sequential treatment. Differences were found in the expression of NAD biosynthetic enzymes during neuronal differentiation, namely, increased QPRT gene expression along the course of RA/BDNF treatment and NAPRT protein expression after a 5-day treatment with RA. QPRT inhibition in BDNF-differentiated SH-SY5Y cells resulted in less neuritic length per cell, decreased expression of the neuronal marker β-III Tubulin and also decreased NAD+ levels and HDAC activity. NAPRT inhibition had no effect in neuritic length per cell, NAD+ levels and HDAC activity. Of note, NAD supplementation along with RA, but not with BDNF, resulted in considerable cell death. Conclusions: Taken together, our results show the involvement of NAD metabolism in neuronal differentiation, specifically, the importance of QPRT-mediated NAD biosynthesis in BDNF-associated SH-SY5Y differentiation and suggest additional roles for NAPRT beyond NAD production in RA-differentiated cells.
- Are relationally transparent leaders more receptive to the relational transparency of others? An authentic dialog perspectivePublication . Rego, Arménio; Cunha, Miguel Pina e; Giustiniano, LucaUsing a sample of 114 leaders (described by 516 team members), we show empirically that the association between leader relational transparency and leader receptiveness to relational transparency of team members is indirect (through leader respect) and conditional on leader humility. When a transparent leader expresses humility, he/she conveys respect to team members and is perceived as more receptive to the relational transparency of employees toward him/her. The indirect association between leader relational transparency and leader receptiveness to the relational transparency of team members is negative, however, when the leader is perceived as non-humble. Our paper contributes to discussion about the limits of relational transparency as an indicator of authentic leadership. We suggest that what is often described as relational transparency is no more than unidirectional transparency—from leaders to followers. We conclude that transparency (and authenticity) in leaders is relational only when it is bidirectional.
- Academic achievement and emotional and behavioural problems: the moderating role of genderPublication . Dias, Pedro; Veríssimo, Lurdes; Carneiro, Alexandra; Figueiredo, BárbaraThe present study aimed to explore the association between academic achievement and emotional and behavioural problems and the moderation role of gender in this association. 1350 Portuguese school-aged children and adolescents from first to ninth grade (6–15-year-old), part of a national representative sample, were assessed by teachers and parents with questionnaires from the Achenbach System of Empirically Based Assessment (ASEBA). Results show that academic achievement significantly predicts child and adolescent’s internalizing, externalizing, and total problems. Gender moderates the association between academic achievement and child and adolescent’s externalizing and total problems, both at school and in the family context. The results underscore the relevance of academic achievement in children and adolescent’s emotional and behavioural problems, and particularly in boys.
- Psychological symptoms in Italian, Spanish and Portuguese youth during the COVID-19 health crisis: a longitudinal studyPublication . Orgilés, Mireia; Francisco, Rita; Delvecchio, Elisa; Espada, José P.; Mazzeschi, Claudia; Pedro, Marta; Morales, AlexandraAiming to slow down the spread of the COVID-19, a lockdown was declared in the first term of 2020 in many European countries, applying different restrictions measures. Although the psychological effects of home confinement in children have been described, there is a lack of longitudinal research examining the impact of the confinement over time. The present study analyzes the evolution of the psychological wellbeing of children and adolescents from three European countries with different restrictions. Parents of 624 Italian, Spanish, and Portuguese children and adolescents aged 3 to 18 years old completed the “Impact Scale of COVID-19 and Home Confinement on Children and Adolescents” two, five, and eight weeks after the lockdown. Results show a different pattern for each country. Children from Italy, the first European country that applied a lockdown, were better adapted than Spanish and Portuguese children the first two weeks after confinement but they were more psychologically impacted by home confinement at the eight-week assessment. Portuguese children, who followed a general duty of home confinement, were the best adapted to the situation, with no significant differences over time. A significant change was found in anxiety symptoms in Spanish children, with a decrease at the last assessment. Findings suggest that long confinements and hard restrictions affect children, so prevention measures should be applied during confinements to prevent psychological problems in children.
- Business group affiliation and SMEs’ international sales intensity and diversification: a multi-country studyPublication . Eduardsen, Jonas; Marinova, Svetla Trifonova; González-Loureiro, Miguel; Vlačić, BožidarThis study examines the impact of business group (BG) affiliation on international sales intensity and diversification in small and medium-sized enterprises (SMEs) by using a multi-country sample of over 13,000 SMEs from 34 European countries. Drawing on the revised Uppsala internationalization model and network theory, this paper suggests that the effects of BG affiliation on international sales intensity and diversification depend on the geographical dispersion of the BG network ties, the size and the age of the firm, and the institutional support in the home country. Thus, we find that interfirm networks in the form of BGs are a double-edged sword that can have both favorable and unfavorable consequences for international sales, depending on the geographical dispersion of the BG's ties. In addition, the results reveal that BG affiliation is more beneficial for smaller SMEs and SMEs in countries with lower institutional support that are more dependent on the network resources embedded within BG networks.
- Estimating labour income‐based inequality of opportunity for a selection of EU‐SILC countries: national and urban‐rural perspectivesPublication . Mogila, Zbigniew; Melo, Patricia C.; Gaspar, José Maria LopesThis paper measures the extent of inequality of opportunity at the national level and by degree of urbanization. Using data from the European Union Statistics on Income and Living Conditions (EU-SILC), we implement regression models to measure the share of the variation in individual’s labour income that is due to uncontrollable circumstances, namely the relative importance of parental education, activity status of parents, occupation of father, and household financial situation. Our results indicate that the level of inequality of opportunity at the country-level ranges between 5% and 26% for the sample of countries studied. The analysis by degree of urbanization does not provide evidence of cities as social elevators compared to less urbanized regions.