Biofunctionalized pectin hydrogels as 3D cellular microenvironments

Pectin hydrogels were prepared by internal ionotropic gelation and explored as MSC delivery vehicles.

Correction: Biofunctionalized pectin hydrogels as 3D cellular microenvironments

Correction for ‘Biofunctionalized pectin hydrogels as 3D cellular microenvironments’ by Sara C. Neves et al., J. Mater. Chem. B, 2015, 3, 2096–2108.

VO₂ kinetics and metabolic contributions during full and upper body extreme swimming intensity

PURPOSE

Our purpose was to characterize the oxygen uptake ([Formula: see text]) kinetics, assess the energy systems contributions and determine the energy cost when swimming front crawl at extreme intensity. Complementarily, we compared swimming full body with upper body only.

METHODS

Seventeen swimmers performed a 100 m maximal front crawl in two conditions: once swimming with full body and other using only the upper propulsive segments. The [Formula: see text] was continuously measured using a telemetric portable gas analyser (connected to a respiratory snorkel), and the capillary blood samples for lactate concentration analysis were collected.

RESULTS

A sudden increase in [Formula: see text] in the beginning of exercise, which continuously rose until the end of the bout (time: 63.82 ± 3.38 s; [Formula: see text]: 56.07 ± 5.19 ml min(-1) kg(-1); [Formula: see text] amplitude: 41.88 ± 4.74 ml min(-1) kg(-1); time constant: 12.73 ± 3.09 s), was observed. Aerobic, anaerobic lactic and alactic pathways were estimated and accounted for 43.4, 33.1 and 23.5 % of energy contribution and 1.16 ± 0.10 kJ m(-1) was the energy cost. Complementarily, the absence of lower limbs lead to a longer time to cover 100 m (71.96 ± 5.13 s), slower [Formula: see text] kinetics, lower aerobic and anaerobic (lactic and alactic) energy production and lower energy cost.

CONCLUSION

Despite the short duration of the event, the aerobic energy contribution covers about 50 % of total metabolic energy liberation, highlighting that both aerobic and anaerobic energy processes should be developed to improve the 100 m swimming performance. Lower limbs action provided an important contribution in the energy availability in working muscles being advised its full use in this short duration and very high-intensity event.

Optimization of supercoiled HPV-16 E6/E7 plasmid DNA purification with arginine monolith using design of experiments

The progress of DNA vaccines is dependent on the development of suitable chromatographic procedures to successfully purify genetic vectors, such as plasmid DNA. Human Papillomavirus is associated with the development of tumours due to the oncogenic power of E6 and E7 proteins, produced by this virus. The supercoiled HPV-16 E6/E7 plasmid-based vaccine was recently purified with the arginine monolith, with 100% of purity, but only 39% of recovery was achieved. Therefore, the present study describes the application of experimental design tools, a newly explored methodology in preparative chromatography, in order to improve the supercoiled plasmid DNA recovery with the arginine monolith, maintaining the high purity degree. In addition, the importance and influence of pH in the pDNA retention to the arginine ligand was also demonstrated. The Composite Central Face design was validated and the recovery of the target molecule was successfully improved from 39% to 83.5%, with an outstanding increase of more than double, while maintaining 100% of purity.

Electrochemical Synthesis of N-Oxopyridine-2-thionate Complexes of Cd(II): The Crystal Structure of Bis(2,2′-bipyridine)(N-oxopyridine-2-thionate) Cadmium(II) Perchlorate 1/4 (Bipyridine)

The electrochemical oxidation of Cd in acetonitrile solution of 1-hydroxy-2-pyridinethione (HPT) and 2,2′-bipyridine (bipy) affords [Cd(PT)2(bipy)] · H2O and [Cd(PT)(bipy)2]ClO4· 1/4(bipy). The crystal structure of the perchlorate salt shows the molecule to have a distorted octahedral CdN4OS skeleton.

Electrochemical Syntheses of Pyrimidine-2-thiolato Complexes of Nickel(II) / Crystal and Molecular Structure of 2,2′-Bipyridine-bis(pyrimidine-2-thiolato)nickel(II) Monohydrate

The electrochemical oxidation of nickel in pyrimidine-2-thione (pymt H) solution yields a compound of formula [Ni(pymt)2]. When pyridine (py), 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen) are added to the solution phase, the product obtained is a complex [Ni(pymt)2py2] or [Ni(pymt)2L] (L = bipy or phen). The crystal structure of [Ni(pymt)2bipy] · H2O is monoclinic, space group P 21/c, with a = 726.6(2), b = 1586.2(2), c = 1696.7(4) pm, β = 99.04(4)° and Z = 4. The nickel atom has highly distorted octahedral coordination and the pyrimidine-2-thiolato ligand is bidentate, forming two four-membered chelate rings with a small “bite” angle of ca. 68°. The two sulphur atoms are in a trans arrangement. The vibrational and electronic spectra of the compounds are discussed.

Direct Electrochemical Synthesis of Pyrimidine-2-thionato Complexes of Zinc(II) and Cadmium(II): The Crystal Structure of (1,10-Phenanthroline)bis(pyrimidine-2-thionato)cadmium(II)

Zn(pymt)2 and Cd(pymt)2 complexes have been obtained by electrochemical oxidation of anodic zinc or cadmium in acetonitrile solutions of pyrimidine-2-thione (Hpymt). When 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen) was added to the electrochemical cell, the adducts [M(pymt)2(bipy)], or [M(pymt)2(phen)] (M = Zn or Cd) were obtained. Crystals of [Cd(pymt)2phen] are orthorhombic, with a = 9.882(2), b = 12.491(1), c = 16.513(2)Å, space group P212121 and Z = 4. The cadmium atom has distorted octahedral geometry, and one nitrogen atom of each pyrimidine-2-thiolato ligand is not coordinated.

The Electrochemical Synthesis of Neutral Zinc(II) Complexes of Schiff Base Ligands: The Crystal Structure of Bis[N-(4-methylphenyl)salicylaldiminato]zinc(II)

The electrochemical synthesis and physico-chemical properties of neutral zinc(II) complexes of bidentate Schiff bases derived from salicylaldehydes are presented together with the X-ray structure of bis[N-(4-methylphenyl)salicylaldiminato]zinc(II). The crystal is monoclinic, a = 21.877(3), b = 8.801(2), c = 12.027(5) Å, β = 96.55(3)°, space group C2/c. The complex is a monomer, and the zinc atom is tetrahedrally coordinated.

Combined analysis of νμ disappearance and νμ→νe appearance in MINOS using accelerator and atmospheric neutrinos

We report on a new analysis of neutrino oscillations in MINOS using the complete set of accelerator and atmospheric data. The analysis combines the ν(μ) disappearance and ν(e) appearance data using the three-flavor formalism. We measure |Δm(32)(2)| = [2.28-2.46] × 10(-3) eV(2) (68% C.L.) and sin(2)θ(23) = 0.35-0.65 (90% C.L.) in the normal hierarchy, and |Δm(32)(2)| = [2.32-2.53] × 10(-3) eV(2) (68% C.L.) and sin(2)θ(23) = 0.34-0.67 (90% C.L.) in the inverted hierarchy. The data also constrain δ(CP), the θ(23} octant degeneracy and the mass hierarchy; we disfavor 36% (11%) of this three-parameter space at 68% (90%) C.L.

Identification of Genetic Risk Factors for Maxillary Lateral Incisor Agenesis

Tooth agenesis affects 20% of the world population, and maxillary lateral incisors agenesis (MLIA) is one of the most frequent subtypes, characterized by the absence of formation of deciduous or permanent lateral incisors. Odontogenesis is a complex mechanism regulated by sequential and reciprocal epithelial-mesenchymal interactions, controlled by activators and inhibitors involved in several pathways. Disturbances in these signaling cascades can lead to abnormalities in odontogenesis, resulting in alterations in the formation of the normal teeth number. Our aim was to study a large number of genes encoding either transcription factors or key components in signaling pathways shown to be involved in tooth odontogenesis. We selected 8 genes— MSX1, PAX9, AXIN2, EDA, SPRY2, TGFA, SPRY4, and WNT10A—and performed one of the largest case-control studies taking into account the number of genes and variants assessed, aiming at the identification of MLIA susceptibility factors. We show the involvement of PAX9, EDA, SPRY2, SPRY4, and WNT10A as risk factors for MLIA. Additionally, we uncovered 3 strong synergistic interactions between MLIA liability and MSX1- TGFA, AXIN2- TGFA, and SPRY2- SPRY4 gene pairs. We report the first evidence of the involvement of sprouty genes in MLIA susceptibility. This large study results in a better understanding of the genetic components and mechanisms underlying this trait.

Injectable MMP-sensitive alginate hydrogels as hMSC delivery systems

Hydrogels with the potential to provide minimally invasive cell delivery represent a powerful tool for tissue-regeneration therapies. In this context, entrapped cells should be able to escape the matrix becoming more available to actively participate in the healing process. Here, we analyzed the performance of proteolytically degradable alginate hydrogels as vehicles for human mesenchymal stem cells (hMSC) transplantation. Alginate was modified with the matrix metalloproteinase (MMP)-sensitive peptide Pro-Val-Gly-Leu-Iso-Gly (PVGLIG), which did not promote dendritic cell maturation in vitro, neither free nor conjugated to alginate chains, indicating low immunogenicity. hMSC were entrapped within MMP-sensitive and MMP-insensitive alginate hydrogels, both containing cell-adhesion RGD peptides. Softer (2 wt % alginate) and stiffer (4 wt % alginate) matrices were tested. When embedded in a Matrigel layer, hMSC-laden MMP-sensitive alginate hydrogels promoted more extensive outward cell migration and invasion into the tissue mimic. In vivo, after 4 weeks of subcutaneous implantation in a xenograft mouse model, hMSC-laden MMP-sensitive alginate hydrogels showed higher degradation and host tissue invasion than their MMP-insensitive equivalents. In both cases, softer matrices degraded faster than stiffer ones. The transplanted hMSC were able to produce their own collagenous extracellular matrix, and were located not only inside the hydrogels, but also outside, integrated in the host tissue. In summary, injectable MMP-sensitive alginate hydrogels can act as localized depots of cells and confer protection to transplanted cells while facilitating tissue regeneration.

Purification of human papillomavirus 16 E6/E7 plasmid deoxyribonucleic acid-based vaccine using an arginine modified monolithic support

The development of efficient plasmid DNA (pDNA) purification processes has fostered therapeutic applications like gene therapy and DNA vaccination. In fact, monolithic supports have emerged as interesting approaches to purify pDNA due to their excellent mass transfer properties and high binding capacity for large biomolecules. The present study describes a method that combines the high selectivity of arginine affinity ligands with the versatility of monoliths to efficiently purify the supercoiled (sc) plasmid HPV-16 E6/E7. Quality control tests indicated that the level of impurities (proteins, endotoxins, gDNA and RNA) in the final plasmid sample was in accordance with the guidelines proposed by regulatory agencies. Breakthrough experiments were designed to compare the dynamic binding capacity of pDNA in the conventional arginine-agarose matrix with the modified monolithic support. The arginine monolith capacity was substantially higher than the conventional arginine-agarose matrix at 10% of breakthrough under the flow rate and pDNA concentration used. Overall, given that the pDNA final product complies with regulatory specifications, this combined support can be the key to obtain an adequate non-viral vaccine against a HPV infection.

Rates of fitness decline and rebound suggest pervasive epistasis

Unraveling the factors that determine the rate of adaptation is a major question in evolutionary biology. One key parameter is the effect of a new mutation on fitness, which invariably depends on the environment and genetic background. The fate of a mutation also depends on population size, which determines the amount of drift it will experience. Here, we manipulate both population size and genotype composition and follow adaptation of 23 distinct Escherichia coli genotypes. These have previously accumulated mutations under intense genetic drift and encompass a substantial fitness variation. A simple rule is uncovered: the net fitness change is negatively correlated with the fitness of the genotype in which new mutations appear—a signature of epistasis. We find that Fisher's geometrical model can account for the observed patterns of fitness change and infer the parameters of this model that best fit the data, using Approximate Bayesian Computation. We estimate a genomic mutation rate of 0.01 per generation for fitness altering mutations, albeit with a large confidence interval, a mean fitness effect of mutations of −0.01, and an effective number of traits nine in mutS⁻E. coli. This framework can be extended to confront a broader range of models with data and test different classes of fitness landscape models.