High temperature magnetic stabilization of cobalt nanoparticles by an antiferromagnetic proximity effect

Thermal activation tends to destroy the magnetic stability of small magnetic nanoparticles, with crucial implications in ultra-high density recording among other applications. Here we demonstrate that low blocking temperature ferromagnetic (FM) Co nanoparticles (TB<70 K) become magnetically stable above 400 K when embedded in a high N\'eel temperature antiferromagnetic (AFM) NiO matrix. The origin of this remarkable TB enhancement is due to a magnetic proximity effect between a thin CoO shell (with low N\'eel temperature, TN; and high anisotropy, KAFM) surrounding the Co nanoparticles and the NiO matrix (with high TN but low KAFM). This proximity effect yields an effective AFM with an apparent TN beyond that of bulk CoO, and an enhanced anisotropy compared to NiO. In turn, the Co core FM moment is stabilized against thermal fluctuations via core-shell exchange-bias coupling, leading to the observed TB increase. Mean-field calculations provide a semi-quantitative understanding of this magnetic- proximity stabilization mechanism

Unravelling the path to create a cell sheet-based model of skin scar-like tissue

Regardless of the advances in understanding the mechanisms and the pathophysiology behind skin deformities, scaring continues to be an unsolved clinical problem. The underlying wound healing process involves a series of key cells which play different key roles. Fibroblasts are known to suffer the influence of local biochemical (e.g TGF-B1) and biomechanical signaling upon a wound scenario leading to a phenotypical change into myofibroblasts. The latter enhance immature extracellular matrix (ECM) synthesis and generate tensional forces that leads to ECM reorganization. Certain skin pathologies (e.g hypertrophic scars) rise from a dysfunction of this underlying regulatory mechanism which in turn drives myofibroblast persistence in the wound. When trying to study the mechanisms behind scarring human ex vivo samples are many times scarce and most of the current in vitro systems rely on standard 2D cultures of keloid/hypertrophic scar fibroblasts. Taking all of this into consideration we propose the use of cell sheet technology to create an in vitro 3D scar model. Herein we report the effect of TGF-B1 in human dermal fibroblast cell sheets as the first step to attain cell sheets with a myofibroblast-like phenotype in which cells are embedded in a scar-like ECM. To further strengthen our concept we performed the stacking of pre-formed cell sheets generating a cohesive 3D scar-like tissue. Human dermal fibroblast (hDFbs) cell sheets were produced as previously described1, and stimulated with TGF-B1 (10ng/ml) over 7, 14 and 21 days. Following phenotype and ECM characterization, cell sheets were stacked in order to obtain a 3D structure composed of 2 or 3 cell-sheets. The analysis of key genes (q-PCR) and proteins (Western blot and immunocytochemistry) showed that hDFbs cell sheets, when stimulated with TGF-B1 present an increased expression of a-SMA, fibronectin (FN) ED- A and FN ED-B, characteristic of a myofibroblast-like phenotype. When looking into the expression of scar ECM-associated proteins, hDFbs cell sheets obtained in the presence of TGF-B1 produced higher amounts of fibronectin and collagen I. Stable 3D constructs with a noticeable level of integration after a total of 21 days of culture, were further created upon stacking of the cell sheets obtained after 7days of culture in the presence of TGF-B1. In conclusion, this work suggested that it is possible to promote the secretion of scar-like ECM in hDFbs cell sheets due to phenotypic changes into myofibroblast-like cells when stimulated with TGF-B1. Cohesive 3D scar-like tissue structures were obtained which opens the possibility to develop a highly accurate in vitro 3D scar model to study underlying cellular mechanisms involved in the wound healing deregulation. Grant IF/00945/2014 funded by FCT/MCTES, Project “NORTE-08-5369-FSE-000044”, funded by Programa Operacional Norte 2020 Fundo Social Europeu, and GENE2SKIN Twinning Project, Horizon 2020, funded by the European Commissioninfo:eu-repo/semantics/publishedVersio

In vitro 3D cell sheet-based model for unraveling scar pathophysiology

Fibroblasts are key players in the scarring process. In hypertrophic scars, fibroblasts suffer phenotypical changes into myofibroblasts persisting in the wound under the influence of local biochemical (TGFb1) and biomechanical signaling leading to enhanced immature extracellular matrix (ECM) synthesis. Benchtop models of hypertrophic scars rely on scarce human ex vivo samples or standard 2D cultures of hypertrophic scar fibroblasts. We therefore propose the use of human dermal fibroblast cell sheets (hDFbsCS) as the first step to attain cell sheets with a myofibroblast-like phenotype to generate cohesive in vitro 3D scar-like tissues. hDFbsCS were produced as previously described (Cerqueira, 2014), and stimulated with TGFb1 up to 21 days. Following phenotype and ECM characterization, 3 hDFbsCS were stacked to obtain a 3D structure. Gene and protein analysis showed that upon TGFb1 stimulation, hDFbsCS present a higher expression of aSMA, fibronectin EDA and EDB, characteristic of amyofibroblast-like phenotype. Regarding the expression of scar ECM-associated proteins, TGFb1 stimulated hDFbsCS produced increased fibronectin and collagen I. Upon stacking of hDFbsCS obtained after 7 days of culture in the presence of TGFb1, stable and integrated 3D constructs were obtained. This work suggests that it is possible to create cohesive 3D scar-like tissue structures from hDFbsCS opening the possibility to develop in vitro 3D scar models to study wound healing deregulation pathophysiology. Acknowledgments: Grant IF.00945.2014 and SFRH.BD. 119756.2016 (FCT MCTES), NORTE.08.5369.FSE.000044 (funded by Programa Operacional Norte 2020 Fundo Social Europeu), GENE2SKIN Twinning Project, Horizon 2020 (European Commission).Grant IF.00945.2014 and SFRH.BD.119756.2016 (FCT_MCTES), NORTE.08.5369.FSE.000044 (funded by Programa_Operacional_Norte_2020 Fundo Social Europeu), GENE2SKIN Twinning Project, Horizon_2020 (European Commission).info:eu-repo/semantics/publishedVersio

The effects of concurrent resistance and endurance training follow a detraining period in elementary school students

The purpose of this study was to compare the effects of an 8-week training period of resistance training alone (GR), or combined resistance and endurance training (GCOM), followed by 12 weeks of detraining (DT) on body composition, explosive strength, and ·VO₂max adaptations in a large sample of adolescent school boys. Forty-two healthy boys recruited from a Portuguese public high school (age: 13.3 ± 1.04 years) were assigned to 2 experimental groups to train twice a week for 8 weeks: GR (n = 15), GCOM (n = 15), and a control group (GC: n = 12; no training program). Significant training-induced differences were observed in 1- and 3-kg medicine ball throw gains (GR: +10.3 and +9.8%, respectively; GCOM: +14.4 and +7%, respectively), whereas no significant changes were observed after a DT period in both the experimental groups. Significant training-induced gains in the height and length of the countermovement (vertical-and-horizontal) jumps were observed in both the experimental groups. No differences were perceived after a DT period in lower limb power. Time at 20 m decreased significantly for both intervention programs (GR: -11.5% and GCOM: -12.4%, <0.00), but either GR or GCOM groups kept the running speed after a DT period of 12 weeks. After training, the ·VO₂max increased only significantly for GCOM (4.6%, p = 0.01). A significant loss was observed after a DT period in GR but not in GCOM. Performing resistance and endurance training in the same workout does not impair strength development in young school boys. As expected, strength training by itself does not improve aerobic capacity. Our results also suggest that training program effects even persist at the end of the DT period.info:eu-repo/semantics/publishedVersio

High spatio-temporal resolution in functional MRI with 3D echo planar imaging using cylindrical excitation and a CAIPIRINHA undersampling pattern

Purpose The combination of 3D echo planar imaging (3D‐EPI) with a 2D‐CAIPIRINHA undersampling scheme provides high flexibility in the optimization for spatial or temporal resolution. This flexibility can be increased further with the addition of a cylindrical excitation pulse, which exclusively excites the brain regions of interest. Here, 3D‐EPI was combined with a 2D radiofrequency pulse to reduce the brain area from which signal is generated, and hence, allowing either reduction of the field of view or reduction of parallel imaging noise amplification. Methods 3D‐EPI with cylindrical excitation and 4 × 3‐fold undersampling in a 2D‐CAIPIRINHA sampling scheme was used to generate functional MRI (fMRI) data with either 2‐mm or 0.9‐mm in‐plane resolution and 1.1‐s temporal resolution over a 5‐cm diameter cylinder placed over both temporal lobes for an auditory fMRI experiment. Results Significant increases in image signal‐to‐noise ratio (SNR) and temporal SNR (tSNR) were found for both 2‐mm isotropic data and the high‐resolution protocol when using the cylindrical excitation pulse. Both protocols yielded highly significant blood oxygenation level–dependent responses for the presentation of natural sounds. Conclusion The higher tSNR of the cylindrical excitation 3D‐EPI data makes this sequence an ideal choice for high spatiotemporal resolution fMRI acquisitions. Magn Reson Med 79:2589–2596, 2018. © 2017 International Society for Magnetic Resonance in Medicine

Intrinsic and Extrinsic Motivation in Physical Education Class and the Differences between Two Educational Pathways

This study aimed to determine the most and least important reasons for engaging in physical education classes among students in two educational pathways within the context of intrinsic and extrinsic motivation. Forty-one students participated in the study (25 males and 16 females; mean age = 16.37 ± 0.829). The sample was divided based on two class types: regular education and professional education. All students answered a questionnaire that aimed to verify the most and least important reasons for students to engage in physical education classes concerning intrinsic and extrinsic motivation.&nbsp; Indicated that both regular education and professional education classes had intrinsic and extrinsic motivation. The results also revealed that the participation of students was based essentially on their intrinsic motivation, but for different reasons when comparing the two educational pathways. Both types of the class were intrinsically and extrinsically motivated to participate in physical education classes

The development of basketball players: current perspectives and future directions

The identification and development of talent in basketball has been seen as a dynamic and complex process. Furthermore, there are numerous factors that play an important role in the evolution of the basketball player during childhood and adolescence. In this brief review, we critically analyze the main factors to be considered in the development of young basketball players. Furthermore, it focuses on the importance of key variables considered in the talent detection process and in long-term development programs. It can be concluded that the maturational status of young basketball players should be considered in the formulation of test batteries for talent detection and in long-term development programs to ensure that potential talents are not excluded due to late maturation in relation to their pairs

Dermal extracellular matrix extracts for wound healing: a pleiotropic trigger

Apresentação efetuada no "Tissue Engineering and Regenerative Medicine International Society (TERMIS) European Chapter Meeting" , em Manchester, Reino Unido, 2023INTRODUCTION: Extracellular matrix (ECM) role is defined by direct cell‐ECM interactions and biomechanics and also by its capacity to store biochemical cues that are vital in tissue's repair. With this in mind, an in‐house method was devised to obtain extracts comprised of structural ECM components (strECM) and enriched in soluble ECM‐derived factors (sECM). Herein we hypothesised that each ECM fraction may trigger different biological functions in multiple cell types, objectively confering them therapeutic and biomimetic potential. METHODS: To prove the concept, we used human dermal fibroblasts (hdFBs) to obtain the ECM extracts, prepared by fractioning cultured cells' own ECM. Extracts were analysed by mass spectrometry to obtain a proteomic profile and then regarding their in vitro functionality. Human dermal endothelial cells (hDMECs), keratinocytes (hKCs) and dFBs, were used to confirm the features identified by the proteomic profiling. The effect of the extracts over cell adhesion (focal adhesion formation) was analysed. A Matrigel assay was used to evaluate a potential angiogenic effect of the extracts. Moreover, hKCs migration and ability to differentiate and form a stratified epidermis was assessed. Finally, matrix (Collagen, elastin, GAGs) deposition by hdFBs and metalloproteinases (MMP 1, 2, 9)secretion and activity were measured. RESULTS: Proteomic analysis revealed that strECM and sECM complement each other, preserving the native ECM protein profile. The GO accessions linked to each fraction allowed pinpointing the specific cues provided by either of them. strECM was mainly comprised of components that were able to promote cell adhesion and spatial organization. On the other hand sECM proteomic profile revealed factors that play a role in wound healing such as angiogenesis, ECM remodeling and re‐epithelialization. A dose‐dependent response was observed regarding the formation of tubular structures in the angiogenic assay. The presence of sECM leads to a significant increase in the migration and proliferative ability (Ki67) of hKCs while maintaining their phenotype. Finally, sECM led to enhanced collagen, elastin and GAGs deposition by hDFbs while increasing the expression of MMPs. DISCUSSION & CONCLUSIONS: Our results validate the hypothesis that each ECM fraction effectively triggers different biological functions in multiple cell types. Overall the presence of sECM boosted the major cellular mechanisms that lead to successful wound healing, while strECM provides cues for cellular adhesion and organization. This study supports the use of ECM extracts as a wound healing enhancer, which might aid in the development of future therapies or improve the biomimicry of ECM‐based 3D tissue models

High-intensity interval training upon cognitive and psychological outcomes in youth : a systematic review

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Development of innovative and time-efficient strategies to involve youth in physical activity is pivotal in the actual inactivity pandemic. Moreover, physical activity may improve academic performance, of great interest for educators. This present systematic review aimed to analyze the effects of high-intensity interval training (HIIT) on cognitive performance and psychological outcomes in youth. A database search (Web of Science, PubMed, Scopus, and PsycINFO) for original research articles was performed. A total of eight articles met the inclusion criteria, and the Cochrane risk of bias tool was used. The studies' results were recalculated to determine effect sizes using Cohen's d. Different HIIT interventions reported improvements on cognitive performance at executive function (d = 0.75, +78.56%), linguistic reasoning (d = 0.25, +7.66%), concentration (d = 0.71, +61.10%), selective attention (d = 0.81, +60.73%), non-verbal and verbal abilities (d = 0.88, +47.50%; d = 1.58, +22.61%, respectively), abstract reasoning (d = 0.75, +44.50%), spatial and numerical abilities (d = 37.19, +22.85%; d = 1.20, +8.28%, respectively), and verbal reasoning (d = 1.00, +15.71%) in youth. Regarding psychological outcomes, HIIT showed higher self-concept (d = 0.28, +8.71%) and psychological well-being in boys and girls (d = 0.73, +32.43%, d = 0.39, +11.58%, respectively). To sum up, HIIT interventions between 4-16 weeks, for 8-30 min/session, at ≥85% maximal heart rate, would provide positive effects on cognitive performance and psychological outcomes in youth.This research was funded by Portuguese Foundation for Science and Technology (FCT, I.P.), under the project UIDB/04045/2020.info:eu-repo/semantics/publishedVersio