126 research outputs found
Multivalent Lactose–Ferrocene Conjugates Based on Poly (Amido Amine) Dendrimers and Gold Nanoparticles as Electrochemical Probes for Sensing Galectin-3
Galectin-3 is considered a cancer biomarker and bioindicator of fibrosis and cardiac remodeling and, therefore, it is desirable to develop convenient methods for its detection. Herein, an approach based on the development of multivalent electrochemical probes with high galectin-3 sensing abilities is reported. The probes consist of multivalent presentations of lactose–ferrocene conjugates scaffolded on poly (amido amine) (PAMAM) dendrimers and gold nanoparticles. Such multivalent lactose–ferrocene conjugates are synthesized by coupling of azidomethyl ferrocene–lactose building blocks on alkyne-functionalized PAMAM, for the case of the glycodendrimers, and to disulfide-functionalized linkers that are then used for the surface modification of citrate-stabilized gold nanoparticles. The binding and sensing abilities toward galectin-3 of both ferrocene-containing lactose dendrimers and gold nanoparticles have been evaluated by means of isothermal titration calorimetry, UV–vis spectroscopy, and differential pulse voltammetry. The highest sensitivity by electrochemical methods to galectin-3 was shown by lactosylferrocenylated gold nanoparticles, which are able to detect the lectin in nanomolar concentrations
Synthesis of phosphoramidite monomers equipped with complementary bases for solid-phase DNA oligomerization
We describe the preparation of two monomers that bear complementary nucleobases at the edges (guanine-2′-deoxycytidine and 2- aminoadenine-2′-deoxyuridine) and that are conveniently protected and activated for solid-phase automated DNA synthesis. We report the optimized synthetic routes leading to the four nucleobase derivatives involved, their crosscoupling reactions into dinucleobase-containing monomers, and their oligomerization in the DNA synthesizerFunding from the European Research Council (ERC-Starting Grant 279548 PROGRAM-NANO) and MINECO (CTQ2014-57729-P, SAF2017-87305-R and CTQ2017- 84727-P) is gratefully acknowledge
Peptide-oligonucleotide conjugates as nanoscale building blocks for assembly of an artificial three-helix protein mimic
Peptide-based structures can be designed to yield artificial proteins with specific folding patterns and functions. Template-based assembly of peptide units is one design option, but the use of two orthogonal self-assembly principles, oligonucleotide triple helix and a coiled coil protein domain formation have never been realized for de novo protein design. Here, we show the applicability of peptide–oligonucleotide conjugates for self-assembly of higher-ordered protein-like structures. The resulting nano-assemblies were characterized by ultraviolet-melting, gel electrophoresis, circular dichroism (CD) spectroscopy, small-angle X-ray scattering and transmission electron microscopy. These studies revealed the formation of the desired triple helix and coiled coil domains at low concentrations, while a dimer of trimers was dominating at high concentration. CD spectroscopy showed an extraordinarily high degree of α-helicity for the peptide moieties in the assemblies. The results validate the use of orthogonal self-assembly principles as a paradigm for de novo protein design
Modeling Semi-Arid River-Aquifer Systems With Bayesian Networks and Artificial Neural Networks
In semiarid areas, precipitations usually appear in the form of big and brief floods, which affect the aquifer through water infiltration, causing groundwater temperature changes. These changes may have an impact on the physical, chemical and biological processes of the aquifer and, thus, modeling the groundwater temperature variations associated with stormy precipitation episodes is essential, especially since this kind of precipitation is becoming increasingly frequent in semiarid regions. In this paper, we compare the predictive performance of two popular tools in statistics and machine learning, namely Bayesian networks (BNs) and artificial neural networks (ANNs), in modeling groundwater temperature variation associated with precipitation events. More specifically, we trained a total of 2145 ANNs with different node configurations, from one to five layers. On the other hand, we trained three different BNs using different structure learning algorithms. We conclude that, while both tools are equivalent in terms of accuracy for predicting groundwater temperature drops, the computational cost associated with the estimation of Bayesian networks is significantly lower, and the resulting BN models are more versatile and allow a more detailed analysis
Physical and psychological paths toward less severe fibromyalgia: A structural equation model
The authors gratefully acknowledge all the participants for their
collaboration and enthusiasm. We thank the assistant researchers
involved in this study and all the members of the Physical Activity
for HEaLth Promotion (PA-HELP; CTS-1018) research group.Supplementary data associated with this article can be found, in
the online version, at https://doi.org/10.1016/j.rehab.2019.06.017.Objectives: Previous research suggested isolated associations of physical and psychological factors with
fibromyalgia severity. Integration of physical and psychological, experienced and observed, modifiable
factors associated with fibromyalgia severity in a single model will reveal therapeutic paths toward less
severity of disease. We aimed to examine an encompassing model of determinants of fibromyalgia
severity.
Methods: This observational, population-based cross-sectional study included 569 people with
fibromyalgia. An integrative model of fibromyalgia severity was tested by using structural equation
modelling. This model included 8 factors: resilience, catastrophizing, active lifestyle, declarative
memory, subjective fitness, objective fitness, psychological distress, and physical fatigue.
Results: Two core paths were associated with reduced fibromyalgia severity: 1) a psychological path
connecting high resilience and low catastrophizing with low distress and 2) a physical path, connecting a
more active lifestyle (directly and via high objective and subjective physical fitness) with low fatigue.
Additional interconnecting paths especially suggested a connection from the psychological to physical
path. Our model explained 83% of the fibromyalgia severity.
Conclusions: The present model integrated the complexity of mutually influencing factors of fibromyalgia
severity, which may help to better understand the disease. It emphasised the importance of: 1) physical
factors and psychological factors and their interconnections, 2) patients’ experiences and clinical
measurements, and 3) positive and negative signs such as physical fitness and distress. Future
longitudinal and experimental research should aim at testing the causal direction of the associations in
the model as well as the clinical implications suggested by the model. For instance, to reduce fatigue,
exercise should enhance not only objective fitness but also fitness-related perceptions. Reducing distress
and fatigue seems crucial for lowering fibromyalgia severity.This work was supported by the Spanish Ministry of Economy and Competitiveness [I+D+i DEP2010-15639, I+D+I DEP2013-40908, I+D+I PSI2015-65241-R, and BES-2014-067612] and the Spanish Ministry of Education [FPU15/00002]. This study was funded in part by the University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES), and the Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Fund (ref. SOMM17/6107/UGR) and University of Jaén, Plan de Apoyo a la Investigación 2017-2019 [EI_SEJ07_2017]. The funders did not have any role in the study design, data collection and analyses, decision to publish, or preparation of the manuscript
On the dissolution of sponge silica: Assessing variability and biogeochemical implications
The dissolution of the biogenic silica that constitutes the skeletons of silicifying organisms is an important mechanism for regenerating dissolved silicon in the ocean. The silica skeletons deposited to the seafloor after the organisms die keep dissolving until becoming definitively buried. The low dissolution rate of sponge skeletons compared to that of diatom skeletons favors their burial and makes sponges (Phylum Porifera) to function as important silicon sinks in the oceans. However, it remains poorly understood whether the large variety of siliceous skeletons existing in the Porifera involves similar variability in their dissolution rates, which would affect the general conceptualization of these organisms as silicon sinks. Herein we investigated kinetics of silica dissolution for major types of skeletons in the three siliceous lineages of Porifera, following standardized digestion conditions in 1% sodium carbonate with orbital agitation at 85°C. The results are compared with those of a previous study conducted under identical conditions, which considered diatom silica, sponge silica, and lithogenic silica. Unexpectedly, the silica of homoscleromorph sponges dissolved only a bit slower than that of freshly cultured diatoms and as fast as diatom earth. However, the rest of sponge skeletons were far more resistant, although with some differences: the isolated spicules of hexactinellid sponges dissolved slightly faster than when forming frameworks of fused spicules, being hexactinellid frameworks as resistant to dissolution as the silica of demosponges, irrespective of occurring in the form of isolated spicules or frameworks. The experiments also indicated that the complexation of sponge silica with aluminum and with chitin does not increase its resistance to dissolution. Because the rapidly-dissolving homoscleromorph sponges represent less than 1% of extant sponges, the sponge skeletons are still conceptualized as important silicon sinks due to their comparative resistance to dissolution. Yet, the turnover of silica into dissolved silicon will always be faster in environments dominated by hexactinellids with isolated spicules than in environments dominated by other hexactinellids and/or demosponges. We discuss whether the time required for a given silica type to completely dissolve in 1% sodium carbonate could be a predictor of its preservation ratio in marine sediments
Sedimentary thickness distribution in the Protector and Pirie basins (Scotia Sea, Antarctica): control factors
Se ha realizado un análisis de estratigrafía sísmica mediante perfiles sísmicos
de reflexión multicanal en las cuencas de Protector y Pirie, las cuales
están ubicadas en el en el Mar de Scotia meridional, en las proximidades
del límite de placas Scotia-Antártica. Mediante este análisis se ha determinado
la distribución de los deposcentros sedimentarios más importantes, lo
que ha permitido comprobar que la distribución sedimentaria en dichas
cuencas está controlada por la morfoestructura del basamento e influenciada
por la distribución de las masas de agua profundas. Los resultados obtenidos
permiten establecer que ambas cuencas constituyen un buen ejemplo
de cuencas oceánicas profundas aisladas y desnutridas, sin aportes continentales
y bajo la influencia de corrientes de fondo activas relacionadas
con el Agua Profunda Circumpolar Antártica (CDW) y con el Agua Profunda
procedente del Mar de Weddell (WSDW)The analysis of multichannel seismic profiles reveals that the distribution
of sedimentary depocenters within the Protector and Pirie basins of the
southern Scotia Sea, close to the Scotia-Antarctica plate boundary, is largely
due to the morpho-structural control of the basement and influenced by the
distribution of bottom currents. Both basins constituted a good example of
small isolated and undernourished deep basins, lacking major continental
inputs and under the influence of active bottom currents related to both the
Antarctic Circumpolar deep Water and the Weddell Sea Deep Wate
Slow Formation of Pseudorotaxanes in Water
The synthesis of two water-soluble oligophenylene-ethynylene (OPE)-rods with substituted iso- and terephthalate end groups is presented. Both undergo slow association with a Diederich-type cyclophane in aqueous solution. Formation of [2]pseudorotaxanes occurs with reaction half-lives of several hours. Characterization of the supermolecules by 1H-NMR spectroscopy reveals a high thermodynamic stability and kinetic inertness of the pseudorotaxanes. The phthalate precursors are functionalized with peripheral azide groups, which make them modular precursors for construction of mechanically interlocked molecules in water
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