Relationship between X(5)-models and the interacting boson model

The connections between the X(5)-models (the original X(5) using an infinite square well, X(5)-$\beta^8$, X(5)-$\beta^6$, X(5)-$\beta^4$, and X(5)-$\beta^2$), based on particular solutions of the geometrical Bohr Hamiltonian with harmonic potential in the $\gamma$ degree of freedom, and the interacting boson model (IBM) are explored. This work is the natural extension of the work presented in [1] for the E(5)-models. For that purpose, a quite general one- and two-body IBM Hamiltonian is used and a numerical fit to the different X(5)-models energies is performed, later on the obtained wave functions are used to calculate B(E2) transition rates. It is shown that within the IBM one can reproduce well the results for energies and B(E2) transition rates obtained with all these X(5)-models, although the agreement is not so impressive as for the E(5)-models. From the fitted IBM parameters the corresponding energy surface can be extracted and it is obtained that, surprisingly, only the X(5) case corresponds in the moderate large N limit to an energy surface very close to the one expected for a critical point, while the rest of models seat a little farther.Comment: Accepted in Physical Review

Four-body continuum-discretized coupled-channels calculations: Application to 6He+64Zn at 13.6 MeV

The recently developed four-body continuum-discretized coupled-channels (CDCC) method, making use of the binning procedure [1], is applied to the reaction 6He+64Zn at 13.6 MeV (around the Coulomb barrier). Excellent agreement with available elastic data [2] is found.Dirección General de Investigación Científica y Técnica FIS 2008-04189, FPA 2006- 13807-C02-01U.S. Department of Energy DE-AC52-07NA27344U.K. STFC EP/D00362

The growth threshold conjecture: a theoretical framework for understanding T-cell tolerance

Adaptive immune responses depend on the capacity of T cells to target specific antigens. As similar antigens can be expressed by pathogens and host cells, the question naturally arises of how can T cells discriminate friends from foes. In this work, we suggest that T cells tolerate cells whose proliferation rates remain below a permitted threshold. Our proposal relies on well-established facts about T-cell dynamics during acute infections: T-cell populations are elastic (they expand and contract) and they display inertia (contraction is delayed relative to antigen removal). By modelling inertia and elasticity, we show that tolerance to slow-growing populations can emerge as a population-scale feature of T cells. This result suggests a theoretical framework to understand immune tolerance that goes beyond the self versus non-self dichotomy.M.A.H. has been partially supported by MINECO grant no. MTM2014-53156. The rest of the authors have not received any particular financial support for this work

Layer-by-layer assembly of chitosan and recombinant biopolymers into biomimetic coatings with multiple stimuli-responsive properties

In this work, biomimetic smart thin coatings using chitosan and a recombinant elastin-like recombinamer (ELR) containing the cell attachment sequence arginine–glycine–(aspartic acid) (RGD) are fabricated through a layer-by-layer approach. The synthetic polymer is characterized for its molecular mass and composition using mass spectroscopy and peptide sequencing. The adsorption of each polymeric layer is followed in situ at room temperature and pH 5.5 using a quartz-crystal microbalance with dissipation monitoring, showing that both polymers can be successfully combined to conceive nanostructured, multilayered coatings. The smart properties of the coatings are tested for their wettability by contact angle (CA) measurements as a function of external stimuli, namely temperature, pH, and ionic strength. Wettability transitions are observed from a moderate hydrophobic surface (CAs approximately from 62° to 71°) to an extremely wettable one (CA considered as 0°) as the temperature, pH, and ionic strength are raised above 50 °C, 11, and 1.25 m, respectively. Atomic force microscopy is performed at pH 7.4 and pH 11 to assess the coating topography. In the latter, the results reveal the formation of large and compact structures upon the aggregation of ELRs at the surface, which increase water affinity. Cell adhesion tests are conducted using a SaOs-2 cell line. Enhanced cell adhesion is observed in the coatings, as compared to a coating with a chitosan-ending film and a scrambled arginine–(aspartic acid)–glycine (RDG) biopolymer. The results suggest that such films could be used in the future as smart biomimetic coatings of biomaterials for different biomedical applications, including those in tissue engineering or in controlled delivery systems.EUJCyL - VA034A09, VA030A08Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/61126/2009, SFRH/BD/61390/2009MICINN - MAT 2007-66275-C02-01, MAT 2007-61604, MAT 2009-14195-C03-03, PSE-300100-2006-1European regional development fund (ERDF)Junta de Castilla y LeonNetwork Center of Regenerative Medicine and Cellular Therapy of Castilla and LeónCIBER-BBN (project CB06-01-0003

Soil health—a new challenge for microbiologists and chemists

Soil health refers to the biological, chemical, and physical features of soil that are essential to long-term, sustainable agricultural productivity with minimal environmental impact. Thus, soil health provides an overall picture of soil functionality. Although it cannot be measured directly, soil health can be inferred by measuring specific soil properties (e.g. organic matter content) and by observing soil status (e.g. fertility). There is also increased interest in studying soil microorganisms in their particular environments, as microbial diversity is intimately related to soil structure and function. One of the key objectives in determining soil health is to acquire indicators that can be used to evaluate the soil’s current status and hence to develop sustainable agricultural systems. In this regard, significant progress has been made over the last few years in the development of specific biomarkers and macromolecular probes, enabling rapid and reliable measurements of soil microbial communities. In addition, modern molecular biological techniques, such as fluorescence in situ hybridization (FISH), reverse transcriptase polymerase chain reaction (RT-PCR), denaturing gradient gel electrophoresis (DGGE), and terminal restriction fragment length polymorphism (T-RFLP), have facilitated the analysis of microbial biodiversity and activity, whereas the application of modern analytical techniques, such as nuclear magnetic resonance (NMR) and pyrolysisgas chromatography-mass spectrometry (Py-GC-MS), have provided data on soil chemistry. The combination of these two approaches offers promise in determining soil health status. [Int Microbiol 2005; 8(1):13-21

Construction and bioproduction of a "green" synthetic protein-based polymer exhibiting a smart behaviour

Natural occurring elastomeric proteins occur in a wide range of biological systems, fulfilling precise functional roles [Tatham and Shewry, 2000]. Their properties are due to the presence of short repeating oligopeptide sequences contained in fibrous proteins, such as silk fibroin (GAGAGS) and mammalian elastin (VPGVG). Elastin is widely distributed in vertebrate tissues, acting statically in dermis to resist long-term forces and dynamically in arteries to store and release energy rapidly. Natural silk from Bombyx mori (silkworm) has been used for centuries either in textile industry or as biomedical suture material, exhibiting impressive mechanical properties as well as high biocompatibility [Kim et al, 2004]. With the development of protein engineering and nano(bio)technologies in general, it is now possible to use amino acids to design and produce genetically engineered Protein-Based Polymers (PBPs) fully biodegradable that simulate the properties of natural occurring proteins . With the advance in recombinant DNA technology it is possible to precisely control the composition, sequence and length of large molecular weight PBPs [Haider et al, 2000]. Recombinant Elastin-Like Polymers (ELPs) are biopolymers based on the aminoacid sequence VPGXG (V-valine, P-proline, G-glycine), where X, termed the guest residue, is any naturally occurring aminoacid except proline. The most striking feature of the ELPs is their Inverse Temperature Transition (ITT) behaviour. Below a specific critical temperature (Tt) and in the presence of water they are soluble, with the polymer chains relatively extended in a disordered state and fully hydrated mainly by hydrophobic hydration. Above the Tt, the polymer chains hydrophobically fold and adopt a dynamic structure, called β-spiral, stabilized by hydrophobic contacts . The ability of ELPs to self-assemble into nanostructures in response to environmental changes allows their utilization in many devices such as microparticles for controlled drug delivery systems or nanosensors. The polymer poly(VPAVG), a ELP where the central glycine (G) is substituted by a L-alanine (A), was chemically synthesized by Rodríguez-Cabello and co-workers and described by Urry as having thermoplastic properties. These groups reported its characterization, demonstrating its extreme biocompatibility both in vitro and in vivo, as well as the ability to self-assemble, forming microparticles that can entrap active substances during the self-assembling process [Herrero-Vanrell et al, 2005; Rincón et al, 2006]. In the present work a new thermal responsive, biologically synthesized ELP based on the (VPAVG)220 sequence was produced, by recurring to standard molecular genetic tools and, as expected, the polymer displayed an inverse temperature transition (Tt) which could be explored as a purification step. Additionally, the purified polymer (VPAVG)220 showed the ability to self-associate at physiological temperature forming aggregates. The culture media and fermentation conditions were optimized using a Central Composite Design (CCD) approach while exploring the use of low cost carbon sources like lactose and glycerol. Sequence and purity of (VPAVG)220 was confirmed by MALDI TOF analysis and purified polymer was subjected to thermal and physical characterization. Due to its self-assembling behaviour near 34 ºC stable spherical microparticles of a ~1μm diameter were obtained, ready solubilized when a strong undercooling was achieved. Moreover, we have constructed and produced a new set of copolymers (Silk-ElastinLike Polymers – SELPs) consisting of flexible ELP and crystalline silk-like blocks (GAGAGS) at different proportions. By this strategy it was possible to produce a variety of biomaterials with diverse physical properties, such as viscosity and gelation time depending on the number of elastin-blocks and silk-like blocks, respectively [Megeed et al, 2000]. The stability of these SELPs in combination with their biocompatibility and unique mechanical properties, provide the basis of their exploitation for biomedical applications

Isokinetic leg strength and power in elite handball players

Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60º/s and 180º/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60º/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180º/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60º/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180º/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.Actividad Física y Deport

Exploiting the sequence of naturally occurring elastin : construction, production and characterization of a recombinant thermoplastic protein-based polymer

Genetic engineering was used to produce an elastin-like polymer (ELP) with precise amino acid composition, sequence and length, resulting in the absolute control of MW and stereochemistry. A synthetic monomer DNA sequence encoding for (VPAVG)20, was used to build a library of concatemer genes with precise control on sequence and size. The higher molecular weight polymer with 220 repeats of VPAVG was biologically produced in Escherichia coli and purified by hot and cold centrifugation cycles, based on the reversible inverse temperature transition property of ELPs. The use of low cost carbon sources like lactose and glycerol for bacteria cells culture media was explored using Central Composite Design approach allowing optimization of fermentation conditions. Due to its self-assembling behaviour near 33 oC stable spherical microparticles with a size ~ 1μm were obtained, redissolving when a strong undercooling is achieved. The polymer produced showed hysteresis behaviour with thermal absorbing/releasing components depending on the salt concentration of the polymer solution.Ministry of Education and Science (MEC) - MAT2007-66275-C02-01 and NAN2004-08538Fundação para a Ciência e a Tecnologia (FCT) e Fundo Europeu de Desenvolvimento Regional (FEDER) - POCI/CTM/57177/2004Marie Curie Research Training Networks (RTN) Biopolysurf - MRTN-CN-2004-005516Junta de Castilla y Leon - VA087A06, VA016B08 and VA030A08Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/36754/200

Management of wet age-related macular degeneration in Spain: challenges for treat and extend implementation in routine clinical practice

Age-related macular degeneration; Ophthalmology services; Anti-VEGFDegeneración macular relacionada con la edad; Servicios de oftalmología; Anti-VEGFDegeneració macular relacionada amb l’edat; Serveis d’oftalmologia; Anti-VEGFPurpose. To ascertain wet AMD (wAMD) management patterns in Spain. Methods. A two-round Delphi study conducted through a questionnaire-based survey designed from literature review and validated by an independent Steering Committee. Results. Forty-nine retina specialists experienced in wAMD participated by answering the two-round study questionnaire. Retina specialists are the main responsible for wAMD diagnosis and monitoring, including visits and associated procedures, with a median time per visit of 15 minutes. Standard treatment strategies are based on anti-VEGF administration, including standard loading dose administration followed by maintenance with aflibercept or ranibizumab (81% of patients). Although treat and extend (T&E) dosing strategy is considered as optimal for wAMD management (78% of the panelists), the main routine healthcare limitations (i.e., visits overload, reduced staff, short visit time, coordination issues, lack of facilities) conduct to self-defined “flexible” strategies, based on T&E and pro-re-nata (PRN) protocols. Conclusion. Proactive treatment patterns (T&E) are the preferred ones by the retina specialists in Spain. However, their proper implementation is difficult due to healthcare resource limitations, as well as organisation and logistic issues. The use of anti-VEGF agents with longer duration of action could facilitate the use of strict T&E approaches according to routine clinical practices

Myopic maculopathy: Current status and proposal for a new classification and grading system (ATN)

Myopia is a highly frequent ocular disorder worldwide and pathologic myopia is the 4th most common cause of irreversible blindness in developed countries. Pathologic myopia is especially common in East Asian countries. Ocular alterations associated with pathologic myopia, especially those involving the macular area—defined as myopic maculopathy—are the leading causes of vision loss in patients with pathologic myopia. High myopia is defined as the presence of a highly negative refractive error (>−6 to −8 diopters) in the context of eye elongation (26–26.5 mm). Although the terms high myopia and pathologic myopia are often used interchangeably, they do not refer to the same eye disease. The two key factors driving the development of pathologic myopia are: 1) elongation of the axial length and 2) posterior staphyloma. The presence of posterior staphyloma, which is the most common finding in patients with pathologic myopia, is the key differentiating factor between high and pathologic myopia. The occurrence of staphyloma will, in most cases, eventually lead to other conditions such as atrophic, traction, or neovascular maculopathy. Posterior staphyloma is for instance, responsible for the differences between a myopic macular hole (MH)—with and without retinal detachment—and idiopathic MH. Posterior staphyloma typically induces retinal layer splitting, leading to foveoschisis in myopic MH, an important differentiating factor between myopic and emmetropic MH. Myopic maculopathy is a highly complex disease and current classification systems do not fully account for the numerous changes that occur in the macula of these patients. Therefore, a more comprehensive classification system is needed, for several important reasons. First, to more precisely define the disease stage to improve follow-up by enabling clinicians to more accurately monitor changes over time, which is essential given the progressive nature of this condition. Second, unification of the currently-available classification systems would establish standardized classification criteria that could be used to compare the findings from international multicentric studies. Finally, a more comprehensive classification system could help to improve our understanding of the genetic origins of this disease, which is clearly relevant given the interchangeable—but erroneous—use of the terms high and pathologic myopia in genetic researc