CDRsp - Artigos em revistas internacionais
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- MSCs Conditioned Media and Umbilical Cord Blood Plasma Metabolomics and CompositionPublication . Pereira, Tiago; Ivanova, Galya; Caseiro, Ana Rita; Barbosa, Paula; Bártolo, Paulo Jorge; Santos, José Domingos; Luís, Ana Lúcia; Maurício, Ana Colette; Ivanovic, ZoranHuman mesenchymal stem cells (hMSCs) from umbilical cord (UC) blood (UCB) and matrix are tested clinically for a variety of pathologies but in vitro expansion using culture media containing fetal bovine serum (FBS) is essential to achieve appropriate cell numbers for clinical use. Human UCB plasma (hUCBP) can be used as a supplement for hMSCs culture, since UCB is rich in soluble growth factors and due to worldwide increased number of cryopreserved UCB units in public and private banks, without the disadvantages listed for FBS. On the other hand, the culture media enriched in growth factors produced by these hMSCs in expansion (Conditioned medium - CM) can be an alternative to hMSCs application. The CM of the hMSCs from the UC might be a better therapeutic option compared to cell transplantation, as it can benefit from the local tissue response to the secreted molecules without the difficulties and complications associated to the engraftment of the allo- or xeno-transplanted cells. These facts drove us to know the detailed composition of the hUCBP and CM, by 1H-NMR and Multiplexing LASER Bead Technology. hUCBP is an adequate alternative for the FBS and the CM and hUCBP are important sources of growth factors, which can be used in MSCs-based therapies. Some of the major proliferative, chemotactic and immunomodulatory soluble factors (TGF-β, G-CSF, GM-CSF, MCP-1, IL-6, IL-8) were detected in high concentrations in CM and even higher in hUCBP. The results from 1H-NMR spectroscopic analysis of CM endorsed a better understanding of hMSCs metabolism during in vitro culture, and the relative composition of several metabolites present in CM and hUCBP was obtained. The data reinforces the potential use of hUCBP and CM in tissue regeneration and focus the possible use of hUCBP as a substitute for the FBS used in hMSCs in vitro culture.
- Semidirect Products and Split Short Five Lemma in Normal CategoriesPublication . Martins-Ferreira, Nelson; Montoli, Andrea; Sobral, ManuelaIn this paper we study a generalization of the notion of categorical semidirect product, as defined in [6], to a non-protomodular context of categories where internal actions are induced by points, like in any pointed variety. There we define semidirect products only for regular points, in the sense we explain below, provided the Split Short Five Lemma between such points holds, and we show that this is the case if the category is normal, as defined in [12]. Finally, we give an example of a category that is neither protomodular nor Mal’tsev where such generalized semidirect products exist.
- A Decomposition Formula for the Weighted CommutatorPublication . Martins-Ferreira, Nelson; Van der Linden, TimWe decompose the weighted subobject commutator of M. Gran, G. Janelidze and A. Ursini as a join of a binary and a ternary commutator.
- Computer modelling and simulation of a bioreactor for tissue engineeringPublication . Pereira, Rúben F.; Freitas, Dino; Tojeira, Ana; Almeida, Henrique A.; Alves, Nuno; Bartolo, Paulo J.A conventional approach to tissue engineering involves the implantation of porous, biodegradable and biocompatible scaffolds seeded with cells into the defect site. In some strategies, tissue engineering requires the in vitro culture of tissueengineering constructs for implantation later. In this case, bioreactors are used to grow 3D tissues under controlled and monitored conditions. However, the quality of the resulting 3D tissue is highly dependent on the design and dimensions of the bioreactor, as well on the operating conditions. In this work, a computational fluid dynamic software package was used to investigate the influence of cylindrical bioreactor dimensions (length and diameter) on the fluid flow and scaffold shear stress. Computer simulations were performed using three different rotational movements (horizontal, vertical and biaxial rotation) and appropriate boundary conditions. Results show that the effect of the bioreactor length on the scaffold shear stress is more important than the diameter, while high length is associated to low scaffold shear stress. On the other hand, the fluid flows within the bioreactor and scaffold shear stresses are dependent on the rotational movement, being more uniform in the biaxial rotation due to the combination of rotational movements.
- Collagen surface modified poly(ε-caprolactone) scaffolds with improved hydrophilicity and cell adhesion propertiesPublication . Sousa, Inês; Mendes, Ausenda; Pereira, Rúben F.; Bártolo, Paulo J.Poly(ε-caprolactone) (PCL)/collagen scaffolds were produced using a four-step procedure comprising (i) the fabrication of PCL scaffolds through an additive bioextrusion system, (ii) the PCL surface modification using a plasma treatment, (iii) the acrylic acid (AAc) grafting by ultraviolet (UV) polymerization, and (iv) the immobilization of collagen into the scaffold surface through the carbodiimide chemistry. This procedure allowed the quick fabrication of highly porous scaffolds with interconnected pores, well-defined internal architecture and improved cell adhesion properties. The immobilization of collagen into the PCL surface led to a significant enhancement in the hydrophilicity, while the biological tests showed a further improvement in the adhesion of fibroblast cells. These results indicate that the collagen surface modification is an effective strategy to render the hydrophobic nature of PCL and overcome the limited cell interaction of 3D PCL scaffolds.
- Interlaminar fracture in woven carbon/epoxy laminatesPublication . Reis, Paulo N. B. ; Ferreira, José A. M. ; Costa, José D. M. ; Pereira, António M.This paper describes an experimental study developed to characterize the mode I and mode II fracture toughness of carbon/epoxy woven composites, using DCB and ENF tests, respectively. The laminates were manufactured using an epoxy resin and twelve woven balanced bi-directional layers of carbon fibres, all of them with the same orientation (0/90º). Significant instantaneous delaminations were observed particularly for the DCB specimen, which were responsible for an oscillatory behaviour of GI versus crack length. The maximum values obtained for GIC and GIIC were 281 and 1800 J/m2, respectively.
- Tethered Swimming Can Be Used to Evaluate Force Contribution for Short-Distance Swimming PerformancePublication . Morouço, Pedro G.; Marinho, Daniel A.; Keskinen, Kari L.; Badillo, Juan J.; Marques, Mário C.Morouço, PG, Marinho, DA, Keskinen, KL, Badillo, JJ, and Marques, MC. Tethered swimming can be used to evaluate force contribution for short-distance swimming performance. J Strength Cond Res 28(11): 3093-3099, 2014-The purpose of this study was two-fold: (a) to compare stroke and the physiological responses between maximal tethered and free front crawl swimming and (b) to evaluate the contribution of force exertion for swimming performance over short distances. A total of 34 male swimmers, representing various levels of competitive performance, participated in this study. Each participant was tested in both a 30-second maximal tethered swimming test and a 50-m free swimming test. The tethered force parameters, the swimming speed, stroke (stroke rate [SR]), and the physiological responses (increase in blood lactate concentration [ΔBLa], heart rate, and rate of perceived exertion) were recorded and calculated. The results showed no differences in stroke and the physiological responses between tethered and free swimming, with a high level of agreement for the SR and DBLa. A strong correlation was obtained between the maximum impulse of force per stroke and the speed (r = 0.91; p < 0.001). Multiple regression analysis revealed that the maximum impulse and SR in the tethered condition explained 84% of the free swimming performance. The relationship between the swimming speed and maximum force tended to be nonlinear, whereas linear relationships were observed with the maximum impulse. This study demonstrates that tethered swimming does not significantly alter stroke and the physiological responses compared with free swimming, and that the maximum impulse per stroke should be used to evaluate the balance between force and the ability to effectively apply force during sprint swimming. Consequently, coaches can rely on tethered forces to identify strength deficits and improve swimming performance over short distances.
- QEEG indexed frontal connectivity effects of transcranial pulsed current stimulation (tPCS): A sham-controlled mechanistic trialPublication . Saavedra, Laura Castillo; Morales-Quezada, Leon; Doruk, Deniz; Rozinsky, Joanna; Coutinho, Livia; Faria, Paula; Perissinotti, Iago; Wang, Qing-Mei; Fregni, FelipeTranscranial pulsed current stimulation (tPCS) is a non-invasive brain stimulation technique that employs weak, pulsed current at different frequency ranges, inducing electrical currents that reach cortical and subcortical structures. Very little is known about its effects on brain oscillations and functional connectivity and whether these effects are dependent on the frequency of stimulation. Our aim was to evaluate the effects of tPCS with different frequency ranges in cortical oscillations indexed by high-resolution qEEG changes for power and interhemispheric coherence. Thirty-eight healthy subjects were enrolled and received a single 20-min session of either sham or active stimulation with 1 Hz, 100 Hz or random frequency (1–5 Hz). We conducted an exploratory analysis to detect changes in mean power for theta, alpha and beta, and interhemispheric coherence for alpha and theta and four different sub-bands cognitive and non-specific adverse effects were recorded. We found that active stimulation with a random frequency ranging between 1 and 5 Hz is able to significantly increase functional connectivity for the theta and low-alpha band as compared to sham and active stimulation with either 1 or 100 Hz. Based on these findings, we discuss the possible effects of tPCS on resting functional connectivity for low-frequency bands in fronto-temporal areas. Future studies should be conducted to investigate the potential benefit of these induced changes in pathologic states.
- Assessment of the fatigue life of aluminium spot-welded and weld-bonded jointsPublication . Pereira, A. M.; Ferreira, J. A. M.; Antunes, F. V.; Bartolo, P.J.In modern machinery and automobile structures weight reduction and increased durability are the main issues in design. In these applications, lap welded and/or bonded joints are widely used; therefore, tools are needed to accurately predict their fatigue life. This paper is concerned with the fatigue strength of single lap joints formed with thin plates of 6082-T6 aluminium alloy using a high strength two-component epoxy adhesive (Araldite 420 A/B from Hunstman). Experimental S–N curves were obtained for resistance spot-welded and weld-bonded lap joints. The fatigue lives of weld-bonded joints were significantly higher than those of resistance spot-welding joints. In addition, fatigue lives were predicted with Morrow's modified Manson–Coffin (M/M–C) and the Smith–Watson–Topper (S–W–T) damage equations. Elastic–plastic numerical models were developed, replicating the experimental work, in order to obtain local stress and strain fields. An acceptable agreement was obtained between the numerical predictions and the experimental results. The M/M–C damage equation diverged from experimental results for relatively long fatigue lives, while the S–W–T equation gave good predictions for all fatigue lives.
- Cell Therapy with Human MSCs Isolated from the Umbilical Cord Wharton Jelly Associated to a PVA Membrane in the Treatment of Chronic Skin WoundsPublication . Ribeiro, Jorge; Pereira, Tiago; Amorim, Irina; Caseiro, Ana Rita; Lopes, Maria A.; Lima, Joana; Gartner, Andrea; Domingos Santos, José Domingos; Bártolo, Paulo J.; Rodrigues, Jorge Manuel; Mauricio, Ana Colette; Luís, Ana LúciaThe healing process of the skin is a dynamic procedure mediated through a complex feedback of growth factors secreted by a variety of cells types. Despite the most recent advances in wound healing management and surgical procedures, these techniques still fail up to 50%, so cellular therapies involving mesenchymal stem cells (MSCs) are nowadays a promising treatment of skin ulcers which are a cause of high morbidity. The MSCs modulate the inflammatory local response and induce cell replacing, by a paracrine mode of action, being an important cell therapy for the impaired wound healing. The local application of human MSCs (hMSCs) isolated from the umbilical cord Wharton's jelly together with a poly(vinyl alcohol) hydrogel (PVA) membrane, was tested to promote wound healing in two dogs that were referred for clinical examination at UPVET Hospital, showing non-healing large skin lesions by the standard treatments. The wounds were infiltrated with 1000 cells/µl hMSCs in a total volume of 100 µl per cm2 of lesion area. A PVA membrane was applied to completely cover the wound to prevent its dehydration. Both animals after the treatment demonstrated a significant progress in skin regeneration with decreased extent of ulcerated areas confirmed by histological analysis. The use of Wharton's jelly MSCs associated with a PVA membrane showed promising clinical results for future application in the treatment of chronic wounds in companion animals and humans.