Elastic biodegradable starch/ethylene-co-vinyl alcohol fibre-mesh scaffolds for tissue engineering applications

The fabrication of a biomaterial scaffold, with adequate physical and structural properties for tissue engineering applications, is reported. A blend of starch with ethylene-vinyl alcohol (50/50 w/w, SEVA-C) is used to produce 3D fibre-mesh scaffolds by wet-spinning. The scaffolds are characterized in terms of morphology, porosity, interconnectivity, and pore size, using scanning electron microscopy (SEM) and microcomputed tomography (μCT). The degradation behavior, as well as the mechanical properties of the scaffolds, is investigated in presence of alpha-amylase enzyme at physiological concentration. Scaffolds with porosities ranging from 43 to 52%, interconnectivity of ∼70.5% and pore size between 118 and 159 μm, can be fabricated using the proposed methodology. The scaffolds exhibit an elastic behavior in the wet state with a compressive modulus of 7.96±0.32 MPa. Degradation studies show that SEVA-C scaffolds are susceptible to enzymatic degradation by alpha-amylase, confirmed by the increase of weight loss (40% of weight loss after 12 weeks) and presence of degradation products (reducing sugars) in solution. The diameter of SEVA-C scaffolds decreases with degradation time, increasing the overall porosity, interconnectivity and pore size. In vitro cell studies with human osteosarcoma cell line (SaOs-2) showed a nontoxic and cytocompatible behavior of the developed fibre mesh scaffolds. The positive cellular response, together with structural and degradable properties, suggests that 3D SEVA-C fibre-meshes may be good candidates as tissue engineering scaffolds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40504. Copyright © 2014 Wiley Periodicals, Inc.This work was supported by national funds through the Portuguese Foundation for Science and Technology under the scope of the project PTDC/CTM/67560/2006 and by the European Regional Development Fund (ERDF) through the Operational Competitiveness Programme “COMPETE” (FCOMP-01-0124-FEDER-007148)

Surface behavior of pelagic juvenile loggerhead sea turtles in the eastern North Atlantic

Sea turtles bask at the ocean surface, but little is known about the patterns and ecological context of surface behavior in the wild. This study investigated the surface behavior of ten juvenile loggerhead sea turtles (34 - 58 cm straight carapace length) satellite tagged in Madeira, in the pelagic eastern North Atlantic. During a total of 2273 tracking days, turtles moved through oceanic areas with a mean depth of ~3400 m. On average, turtles spent one third of the time at the surface (0 - 1 m depth), spending 43% of the time at the surface during the day and 29% of the time during the night. Generalized linear mixed modelling showed that the proportion of time at the surface was significantly larger during the day, particularly during spring and summer. Time spent at the surface during the day increased with elevated air temperatures and weak winds, probably to maximize the benefits of solar absorption. Conversely, the probability of being at the surface during the day decreased as horizontal search effort increased, suggesting a trade-off between basking and daytime foraging activities. At night, time spent at the surface was not associated with air temperature or wind speed but was instead positively associated with moon illumination. As turtles tend to dive deeper during clear nights, increased surface time may be needed to recover from deeper dives. This study presents important aspects of the behavioral ecology of the species during the oceanic juvenile phase. The findings reported here may be relevant for species management and conservation, including correction of census data and management of interactions with surface fishing gear and other anthropogenic activities.info:eu-repo/semantics/publishedVersio

Evaluating a Novel Class of Biomaterials: Magnesium-Containing Layered Double Hydroxides

Metallic magnesium and compounds such as magnesium hydroxide Mg(OH)2 have been shown to have osteoconductive properties under experimental conditions and are gaining an increasing interest in the field of degradable biomaterials. The application of the compounds as implant coatings could support implant incorporation, resulting in an increased period of use of the implants. A variety of Mg-containing Layered Double Hydroxides (Mg-LDHs) has been synthesized and examined. These materials have been tested in various in vitro and in vivo studies; the latter took place in different sites like in the middle ear or in the condyle of New Zealand White Rabbits. In the latest study newly formed bone could be found around the Mg-Al-CO3-LDH pellets, making it a promising compound for bone-healing applications.DFG/SFB/59

Dynamics of pH-dependent self-association and membrane binding of a dicarboxylic porphyrin: a study with small unilamellar vesicles

AbstractSteady-state and stopped-flow measurements of the absorbance and fluorescence of aqueous solutions were performed to characterize the pH-dependent ionization and aggregation states of deuteroporphyrin. Porphyrin self-association promoted by neutralization of the carboxylic groups takes place within a few milliseconds impeding characterization of the monomer ionization states. Extrapolation at infinite dilution of the values obtained from steady-state measurements yielded the pKs of the carboxylic groups (6.6, 5.3) and inner nitrogens (4.1, 2.3). The kinetics of interactions of the porphyrin with unilamellar fluid state dioleoylphosphatidylcholine vesicles was examined in a large pH range, with focus on the entry step. From alkaline pH to a value of 6.5, the entrance rate is maximal (1.69×106 M−1 s−1 versus phospholipid concentration). It decreases to 2.07×105 M−1 s−1 at lower pH with an apparent pK of 5.39. This effect appears to be related to the formation of porphyrin dimer rather than to the protonation of inner nitrogen. In keeping with previous data, these results support the concept of a pH-mediated selectivity of carboxylic porphyrins for tumor. They also indicate that the propensity of these molecules to self-associate at low pH could yield to some retention in acidic intracellular vesicles of the endosome/lysosome compartment

Diagnostic value of Pentraxin-3 in patients with sepsis and septic shock in accordance with latest sepsis-3 definitions

Background: Pentraxin-3 (PTX-3) is an acute-phase protein involved in inflammatory and infectious processes. This study assesses its diagnostic and prognostic value in patients with sepsis or septic shock in a medical intensive care unit (ICU). Methods: The study includes 213 ICU patients with clinical criteria of sepsis and septic shock. 77 donors served as controls. Plasma levels of PTX-3, procalcitonin (PCT) and interleukin-6 were measured on day 1, 3 and 8. Results: PTX-3 correlated with higher lactate levels as well as with APACHE II and SOFA scores (p = 0.0001). PTX-3 levels of patients with sepsis or septic shock were consistently significantly higher than in the control group (p ≤ 0.001). Plasma levels were able to discriminate sepsis and septic shock significantly on day 1, 3 and 8 (range of AUC 0.73–0.92, p = 0.0001). Uniform cut-off levels were defined at ≥5 ng/ml for at least sepsis, ≥9 ng/ml for septic shock (p = 0.0001). Conclusion: PTX-3 reveals diagnostic value for sepsis and septic shock during the first week of intensive care treatment, comparable to interleukin-6 according to latest Sepsis-3 definitions. Trial registration: NCT01535534. Registered 14.02.201

Blood biochemistry reference values for wild juvenile loggerhead sea turtles (Caretta caretta) from Madeira archipelago

Standard biochemical parameters were determined in wild juvenile loggerhead sea turtles Caretta caretta living offshore Madeira Island, northeast Atlantic. We analyzed the influence of age, sex, sea surface temperature, and body condition index on biochemical parameters including uric acid, total bilirubin, total cholesterol, creatinine kinase (CK), glucose, total protein, urea nitrogen, lactate dehydrogenase, aspartate aminotranspherase (AST), gamma-glutamyl transferase (GGT), albumin, alkaline phosphatase (ALP), sodium (NA), potassium (K), chloride, calcium, phosphorus, and magnesium. Significant positive correlations were found between turtle body size and total cholesterol, total protein, and albumin. Total protein and the enzymes AST and CK were lower than reported levels in adults. Calcium levels were lower than those reported in adult or captive turtles, but similar to wild juveniles from Australian waters, and were interpreted as normal for this age category. These data may be useful to evaluate the health status of stranded or injured animals and to improve veterinary care at rehabilitation centers.info:eu-repo/semantics/publishedVersio

Larval cestodes infecting the deep-water fish, Cataetyx laticeps (Pisces: Bythitidae) from Madeira Archipelago, Atlantic Ocean

Parasites of deep-water fishes are less known in comparison to the parasites of fishes living in the demersal and epipelagic ocean zones. In the present research note we report the occurrence of larval trypanorhynch cestodes in a rare deep-water fish, the deep-water brotula, Cataetyx laticeps. Based on the 28S rDNA (region D1-D3) sequence homology and the phylogenetic analysis, the larval cestodes are putatively assigned to the genus Grillotia. It is suggested that the definitive host of this trypanorhynch is a batoid.info:eu-repo/semantics/publishedVersio

Identification of likely foraging habitat of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of telemetry track sinuosity

Changes in the behavior of individual animals in response to environmental characteristics can provide important information about habitat preference, as well as the relative risk that animals may face based on the amount of time spent in hazardous areas. We analyzed movement and habitat affinities of ten log gerhead turtles (Caretta caretta) tagged with satellite transmitters in the spring and fall of 1998 near Madeira, Portugal for periods of 2–10 months. We analyzed the behavior of these individuals in relation to the marine environment they occupied. As a measure of behavior we calculated the straightness index (SI), the ratio of the displacement of the animal to the total distance traveled, for individual weekly seg ments of the 10 tracks. We then extracted information about chlorophyll a concentration, sea-surface temperature (SST), bathymetry, and geostrophic current of the ocean in a 20-km buffer surrounding the tracks, and examined their relationship to the straightness index using generalized linear models. Chlorophyll a value, bathymetry and SST were significantly related to the straightness index of the tracks of all ten animals, as was the circular standard deviation of the geostrophic current (Wald’s test: p = 0.001, p = 0.008, p = 0.025, and p = 0.049, respectively). We found a significant negative relationship between straightness index and chlorophyll, and positive relationships with ocean depth and SST indicat ing that animals are spending more time and searching more thoroughly in areas with high chlorophyll concentrations and in areas that are shallower, while moving in straight paths through very warm areas. We also found a positive relationship between straightness index and the circular standard deviation of surrounding geostrophic currents suggesting that these turtles are more likely to move in a straight line when in the presence of diffuse, less-powerful currents. Based on these relationships, we propose that conservation planning to reduce overlap of turtles with fishing operations should take into account the locations of bathymetric features such as seamounts and upwelling locations where chlorophyll concen trations are high. This analysis is an effective way to characterize areas of high-use habitat for satellite tagged marine vertebrates, and allows for comparisons of these characteristics between species and among individuals.info:eu-repo/semantics/publishedVersio

Evidence for trophic differences between live and bycatch oceanic juvenile loggerhead sea turtles

The loggerhead sea turtle Caretta caretta is a vulnerable migratory species that spends its frst years of life in the open sea. During this developmental phase, loggerheads can be found foraging in the epipelagic zone of the waters surrounding the Madeira Archipelago, providing a rare opportunity to gather information on the ecology of its oceanic developmental stage. In this study, we characterized the isotopic niche of these juveniles, using stable isotope analysis. We assessed two groups of turtles, turtles captured alive (n=24) and turtles captured as bycatch on local longlines (n=12), and explored whether animals caught in the local fshing gear represented a random sample of the population, or whether there is some evidence for a specialized foraging behaviour. We found that turtle bycatch had a signifcantly higher mean stable nitrogen isotope value in whole blood (δ15N=8.5±0.6‰ SD) compared to the group of turtles captured alive in the same period (δ15N=7.6±0.5‰ SD), indicating that they had a diferent diet. While there was a tendency for turtle bycatch to be slightly larger, we found no efect of body size on δ15N values. We propose a distinct foraging behaviour strategy hypothesis, with a group of turtles being more susceptible to interactions with fsheries and thus having a higher mortality risk, which should motivate the implementation of existing guidelines to reduce sea turtle bycatch.info:eu-repo/semantics/publishedVersio

Compensatory growth in oceanic loggerhead sea turtles: response to a stochastic environment

Compensatory growth (CG, accelerated growth that may occur when an organism that has grown at a reduced rate as a result of suboptimal environmental conditions is exposed to better conditions) is considered an adaptation to variable en vironments. Although documented thoroughly under captive conditions, CG has rarely been studied in wild populations. In their first years of life, oceanic-stage loggerhead sea turtles (Caretta caretta) have relatively little control over their geographic position or movements and thus have an extremely stochastic lifestyle with great variation in food availability and temperature. This environmental variation results in variable growth rates. We evaluate somatic growth functions of oceanic-stage loggerheads from the eastern Atlantic based on skeletochronology that allowed us to assign age and cohort to each individual. We demonstrate CG in these turtles based on three different analytical approaches: changes in coefficients of variation in size-at-age, generalized additive model regression analyses of somatic growth, and linear regression of age-specific growth rates. As a result of CG, variation in size-at-age in these juvenile loggerheads is substantially reduced. Thus, size is a better predictor of age than expected based on variation in growth rates. CG decreases with age, apparently as loggerheads gain greater control over their movements. In addition, we have evaluated for the first time in wild sea turtles the time-dependent nature of somatic growth by distinguishing among age, year, and cohort effects using a mixed longitudinal sampling design with assigned-age individuals. Age and year had significant effects on growth rates, but there was no significant cohort effect. Our results address critical gaps in knowledge of the demog raphy of this endangered species.info:eu-repo/semantics/publishedVersio