Current concepts and challenges in osteochondral tissue engineering and regenerative medicine

"Publication Date (Web): February 20, 2015"In the last few years, great progress has been made to validate tissue engineering strategies in preclinical studies and clinical trials on the regeneration of osteochondral defects. In the preclinical studies, one of the dominant strategies comprises the development of biomimetic/bioactive scaffolds, which are used alone or incorporated with growth factors and/or stem cells. Many new trends are emerging for modulation of stem cell fate towards osteogenic and chondrogenic differentiations, but bone/cartilage interface regeneration and physical stimulus have been showing great promise. Besides the matrix-associated autologous chondrocyte implantation (MACI) procedure, the matrix-associated stem cells implantation (MASI) and layered scaffolds in acellular or cellular strategy are also applied in clinic. This review outlines the progresses at preclinical and clinical levels, and identifies the new challenges in osteochondral tissue engineering. Future perspectives are provided, e.g., the applications of extracellular matrix-like biomaterials, computer-aided design/manufacture of osteochondral implant and reprogrammed cells for osteochondral regeneration.The authors thank the Portuguese Foundation for Science and Technology (FCT) through the projects TISSUE2TISSUE (PTDC/CTM/105703/2008) and OsteoCart (PTDC/CTM-BPC/115977/2009). We also acknowledge European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement REGPOT-CT2012-316331-POLARIS. L-P.Y. acknowledges the PhD scholarship from FCT (SFRH/BD/64717/2009). The FCT distinction attributed to J.M.O. and A.L.O. under the Investigator FCT program (IF/00423/2012) and (IF/00411/2013) are also greatly acknowledged

An analysis of the positional distribution of DNA motifs in promoter regions and its biological relevance

BACKGROUND: Motif finding algorithms have developed in their ability to use computationally efficient methods to detect patterns in biological sequences. However the posterior classification of the output still suffers from some limitations, which makes it difficult to assess the biological significance of the motifs found. Previous work has highlighted the existence of positional bias of motifs in the DNA sequences, which might indicate not only that the pattern is important, but also provide hints of the positions where these patterns occur preferentially.RESULTS: We propose to integrate position uniformity tests and over-representation tests to improve the accuracy of the classification of motifs. Using artificial data, we have compared three different statistical tests (Chi-Square, Kolmogorov-Smirnov and a Chi-Square bootstrap) to assess whether a given motif occurs uniformly in the promoter region of a gene. Using the test that performed better in this dataset, we proceeded to study the positional distribution of several well known cis-regulatory elements, in the promoter sequences of different organisms (S. cerevisiae, H. sapiens, D. melanogaster, E. coli and several Dicotyledons plants). The results show that position conservation is relevant for the transcriptional machinery.CONCLUSION: We conclude that many biologically relevant motifs appear heterogeneously distributed in the promoter region of genes, and therefore, that non-uniformity is a good indicator of biological relevance and can be used to complement over-representation tests commonly used. In this article we present the results obtained for the S. cerevisiae data sets.publishersversionpublishe

Modulating intermolecular interactions and rheological properties in silk fibroin using ultrasound frequencies

info:eu-repo/semantics/draf

Sugarcane straw polyphenols as potential food and nutraceutical ingredient

The sugarcane processing industry generates a large amount of straw, which has a negative environmental impact, and high costs are associated with their elimination, wasting their potential bioactive value attributed to their richness in polyphenols. In this study, an ethanolic extract produced from sugarcane straw was screened for its phenolic compounds content, and the potential use of this extract in the development of a food ingredient was further evaluated. Fifty different secondary metabolites belonging to the hydroxybenzoic acids, hydroxycinnamic acids, and flavonoids were identified by liquid chromatography–electrospray ionization–ultrahigh-resolution—quadrupole time of flight–mass spectrometry (LC-ESI-UHR-QqTOF-MS). The predominant phenolic compounds found were 4-hydroxybenzaldehyde, chlorogenic acid, and 5-O-feruloylquinic acid. The obtained extracts showed strong potential as food preservatives by exhibiting (a) antioxidant activity using both 2.2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt radical cation (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods; and (b) antimicrobial capacity, with a minimum inhibitory concentration of 50 mg/mL for Staphylococcus aureus, 74% inhibition for Bacillus cereus, and 44% for Salmonella enterica; and (c) the capacity to inhibit a food browning enzyme, tyrosinase (28–73% for 1–8 mg/ mL). Moreover, the extracts showed antidiabetic potential by inhibiting the enzymes α-glucosidase (15–38% for 1.25–5.00 mg/mL) and dipeptidyl peptidase-IV (DPP-IV) (62–114% for 0.31–5.00 mg/mL). The extract (0.625 mg/mL) also exhibited the capacity to reduce proinflammatory mediators (i.e., interleukins 6 and 8, and tumor necrosis factor alpha) when Caco-2 cells were stimulated with interleukin 1 beta. Thus, sugarcane straw extract, which is rich in phenolic compounds, showed high potential to be used in the development of food-preservative ingredients owing to its antioxidant and antimicrobial potential, and to be explored as a food supplement in diabetes prevention and as coadjuvant to reduce intestinal inflammation by reducing proinflammatory mediators.info:eu-repo/semantics/publishedVersio

Spatiotemporal assessment of particulate matter (PM10 and PM2.5) and ozone in a Caribbean urban coastal city

Air pollution has become a critical issue in urban areas, so a broad understanding of its spatiotemporal characteristics is important to develop public policies. This study analyzes the spatiotemporal variation of atmospheric particulate matter (PM10 and PM2.5) and ozone (O3) in Barranquilla, Colombia from March 2018 to June 2019 in three monitoring stations. The average concentrations observed for the Móvil, Policía, and Tres Avemarías stations, respectively, for PM10: 46.4, 51.4, and 39.7 μg/m3; for PM2.5: 16.1, 18.1, and 15.1 μg/m3 and for O3: 35.0, 26.6, and 33.6 μg/m3. The results indicated spatial and temporal variations between the stations and the pollutants evaluated. The highest PM concentrations were observed in the southern part of the city, while for ozone, higher concentrations were observed in the north. These variations are mainly associated with the influence of local sources in the environment of each site evaluated as well as the meteorological conditions and transport patterns of the study area. This study also verified the existence of differences in the concentrations of the studied pollutants between the dry and rainy seasons and the contribution of local sources as biomass burnings from the Isla Salamanca Natural Park and long-range transport of dust particles from the Sahara Desert. This study provides a scientific baseline for understanding air quality in the city, which enables policy makers to adopt efficient measures that jointly prevent and control pollution

Drug Delivery Systems and Flavonoids: Current Knowledge in Melanoma Treatment and Future Perspectives

Melanoma is an aggressive form of skin cancer with a high prevalence in the population. An early diagnosis is crucial to cure this disease. Still, when this is not possible, combining potent pharmacological agents and effective drug delivery systems is essential to achieve optimal treatment and improve patients' quality of life. Nanotechnology application in biomedical sciences to encapsulate anticancer drugs, including flavonoids, in order to enhance therapeutic efficacy has attracted particular interest. Flavonoids have shown effectiveness against various types of cancers including in melanoma, but they show low aqueous solubility, low stability and very poor oral bioavailability. The utilization of novel drug delivery systems could increase flavonoid bioavailability, thereby potentiating its antitumor effects in melanoma. This review summarizes the potential of different flavonoids in melanoma treatment and the several nanosystems used to improve their biological activity, considering published information that reported improved biological and pharmacological properties of encapsulated flavonoids.publishe

Recent advances in silk sericin/calcium phosphate biomaterials

Calcium phosphates (CaPs) have been widely used in the field of biomedical engineering as bone graft substitutes or as carriers for drug delivery applications. Recent developments have focused on combining CaPs with proteins to obtain functional biomaterials that accommodate a broader spectrum of functional requirements. Silk sericin was considered an unutilized protein by-product from the textile industry, generating tons of residues every year. However, much effort has been dedicated to its recovery after being associated with numerous biological properties such as antioxidant, antibacterial, anti-coagulation and regenerative activities. In the past years, sericin has also demonstrated to be suitable as a template for CaPmineralization. The present review focuses on the recent developments for the production of sericin/CaP composites, exploring their potential applications in bioengineering and opening new avenues in other research fields such as in the cosmetic, food and environmental sectors. In addition, this paper can also be useful as a guideline to design future research based on sericin/CaP biomaterials.info:eu-repo/semantics/publishedVersio

Kinetic study of fermentative biosurfactant production by Lactobacillus strains

Screening of biosurfactant-producing ability of four Lactobacillus strains was performed, being shown that for all the tested strains biosurfactant production occurred mainly in the first 4 h. The Lactobacillus strains showed zones of clearing in the blood agar with a diameter <1 cm. The minimum surface tension value of the fermentation broth achieved was 39.5 mN/m for Lactobacillus pentosus CECT-4023 that represents a reduction in the surface tension of 10.5 mN/m comparing with the control. Time courses of glucose, biomass and biosurfactant were modeled according to reported models. Using MRS broth (Man, Rogosa & Sharpe medium for lactobacilli strains) as culture medium, the values estimated by the modeling of biosurfactant were Pmax = 1.6 g of biosurfactant/L and rp/X = 0.091 g/(L h), for Lactobacillus casei CECT-5275, Pmax = 1.7 g/L and rp/X = 0.217 g/(L h) for Lactobacillus rhamnosus CECT-288, Pmax = 1.7 g/L and rp/X = 0.069 g/(L h) for L. pentosus CECT-4023 and Pmax = 1.8 g/L and rp/X = 0.090 g/(L h) for Lactobacillus coryniformis subsp. torquens CECT-25600. Pmax is the maximum concentration of biosurfactant (g/L), and Pr is the ratio between the initial volumetric rate of product formation (rp) and the initial product concentration P0 (g/L). Using whey as production medium, the values estimated by the modeling of biosurfactant for L. pentosus CECT-4023 were Pmax = 1.4 g of biosurfactant/L and rp/X = 0.093 g/(L h). In conclusion, the results obtained for L. pentosus CECT-4023 showed that this is a strong biosurfactant producer strain and that cheese whey can be used as an alternative medium for biosurfactant production

Modeling of biosurfactant production by Lactobacillus Strains

Screening of biosurfactant-producing ability of three Lactobacillus strains was performed, being shown that, for all the tested strains, biosurfactant production is occurring mainly in the first 7 hours. All strains reduced 8 mN/m the surface tension of the fermentation broth at the end of fermentation and lysed blood agar with scores ranging between (++) corresponding to complete hemolysis with a diameter < 1 cm. Time courses of lactose, biomass and biosurfactant were modeled according to reported models, assuming product inhibition. Using optimized MRS broth as culture medium, the values estimated by the modeling of biosurfactant were P_max = 1.4 g of biosurfactant/L and rp/X = 0.137g/L.hˉ¹ for Lactobacillus casei CECT-5275, P_max = 1.5 g/L and rp/X = 0.145g/L.hˉ¹ for Lactobacillus rhamnosus CECT-288 and P_max = 1.5 g/L and rp/X = 0.089 g/L.hˉ¹ for Lactobacillus pentosus CECT-4023. Using whey as production medium, the values obtained for Lactobacillus rhamnosus CECT-288 were P_max = 1.3 g of biosurfactant/L and rp/X = 0.078 g/L.hˉ¹. In conclusion, the results obtained showed that whey can be used as an alternative medium for biosurfactant production by Lactobacillus strains

Locomotion gait optimization for a quadruped robot

This article describes the development of a gait optimization system that allows a fast but stable robot quadruped crawl gait. We focus in the development of a quadruped robot walking gait locomotion that combine bio-inspired Central Patterns Generators (CPGs) and Genetic Algorithms (GA). The CPGs are modelled as autonomous differential equations, that generate the necessary limb movement to perform the walking gait, and the Genetic Algorithm perform the search of the CPGs parameters. This approach allows to explicitly specify parameters such as amplitude, offset and frequency of movement and to smoothly modulate the generated trajectories according to changes in these parameters. It is therefore easy to combine the CPG with an optimization method. A genetic algorithm determines the best set of parameters that generates the limbs movements. We intend to obtain a walking gait locomotion that minimizes the vibration and maximizes the wide stability margin and the forward velocity. The experimental results, performed on a simulated Aibo robot, demonstrated that our approach allows low vibration with a high velocity and wide stability margin for a quadruped walking gait locomotion