The impact of COVID-19 on social life has been drastic and global. However, the different numbers of cases and different actions in different countries have been leading to various interesting yet ...unexplored effects on human behavior. In the present study, we compare the physical activity and recreational screen time of a representative sample of 1711 4- to 17-year-olds before and during the strictest time of the first COVID-19 lockdown in Germany. We found that sports activity declined whereas recreational screen time increased. However, a substantial increase in habitual physical activities leads to an overall increase in physical activity among children and adolescents in Germany. The effects differ in size but not in their direction between age groups and are stable for boys and girls. We conclude from this natural experiment that physical activity among children and adolescents is highly context-driven and mutual and does not act as a functional opposite to recreational screen time.
Telomerase is the ribonucleoprotein enzyme that catalyzes the extension of telomeric DNA in eukaryotes. Recent work has begun to reveal key aspects of the assembly of the human telomerase complex, ...its intracellular trafficking involving Cajal bodies, and its recruitment to telomeres. Once telomerase has been recruited to the telomere, it appears to undergo a separate activation step, which may include an increase in its repeat addition processivity. This review covers human telomerase biogenesis, trafficking, and activation, comparing key aspects with the analogous events in other species.
The Fenton process, one of several advanced oxidation processes, describes the reaction of Fe(II) with hydrogen peroxide. Fe(II) is oxidized to Fe(III) that reacts with hydrogen peroxide to Fe(II) ...and again initiates the Fenton reaction. In the course of the reactions reactive species, e.g. hydroxyl radicals, are formed. Conditions such as pH, ligand concentrations and the hydrogen peroxide/Fe(II) ratio may influence the OH radical yield. It could be shown that at pH < 2.7 and >3.5 the OH radical yield decreases significantly. Two ligands were investigated, pyrophosphate and sulfate. It was found that pyrophosphate forms a complex with Fe(III) that does not react with hydrogen peroxide and thus, the Fenton reaction is terminated and the OH radical yields do not further increase. The influence of sulfate is not as strong as that of pyrophosphate. The OH radical yield is decreased when sulfate is added but even at higher concentrations the Fenton reaction is not terminated.
•OH yield differs not much after 3 h of reaction in the pH range 1.5–5.•OH yield increases significantly after 24 h of reaction in the pH range 2.7–3.5.•Pyrophosphate forms a stable complex with Fe(III) and terminates the Fenton process.•Sulfate decreases the OH yield in the Fenton process.•At the low sulfate concentration applied the Fenton process is not terminated.
Nonequilibrium Mechanics of Active Cytoskeletal Networks Mizuno, Daisuke; Tardin, Catherine; Schmidt, C.F ...
Science (American Association for the Advancement of Science),
01/2007, Letnik:
315, Številka:
5810
Journal Article
Recenzirano
Cells both actively generate and sensitively react to forces through their mechanical framework, the cytoskeleton, which is a nonequilibrium composite material including polymers and motor proteins. ...We measured the dynamics and mechanical properties of a simple three-component model system consisting of myosin II, actin filaments, and cross-linkers. In this system, stresses arising from motor activity controlled the cytoskeletal network mechanics, increasing stiffness by a factor of nearly 100 and qualitatively changing the viscoelastic response of the network in an adenosine triphosphate-dependent manner. We present a quantitative theoretical model connecting the large-scale properties of this active gel to molecular force generation.
Myosin motor proteins drive vigorous steady-state fluctuations in the actin cytoskeleton of cells. Endogenous embedded semiflexible filaments such as microtubules, or added filaments such as ...single-walled carbon nanotubes are used as novel tools to noninvasively track equilibrium and nonequilibrium fluctuations in such biopolymer networks. Here, we analytically calculate shape fluctuations of semiflexible probe filaments in a viscoelastic environment, driven out of equilibrium by motor activity. Transverse bending fluctuations of the probe filaments can be decomposed into dynamic normal modes. We find that these modes no longer evolve independently under nonequilibrium driving. This effective mode coupling results in nonzero circulatory currents in a conformational phase space, reflecting a violation of detailed balance. We present predictions for the characteristic frequencies associated with these currents and investigate how the temporal signatures of motor activity determine mode correlations, which we find to be consistent with recent experiments on microtubules embedded in cytoskeletal networks.
Background
Allergen immunotherapy (AIT) is an effective treatment for allergic rhinoconjunctivitis (AR) with or without asthma. It is important to note that due to the complex interaction between ...patient, allergy triggers, symptomatology and vaccines used for AIT, some patients do not respond optimally to the treatment. Furthermore, there are no validated or generally accepted candidate biomarkers that are predictive of the clinical response to AIT. Clinical management of patients receiving AIT and efficacy in randomised controlled trials for drug development could be enhanced by predictive biomarkers.
Method
The EAACI taskforce reviewed all candidate biomarkers used in clinical trials of AR patients with/without asthma in a literature review. Biomarkers were grouped into seven domains: (i) IgE (total IgE, specific IgE and sIgE/Total IgE ratio), (ii) IgG‐subclasses (sIgG1, sIgG4 including SIgE/IgG4 ratio), (iii) Serum inhibitory activity for IgE (IgE‐FAB and IgE‐BF), (iv) Basophil activation, (v) Cytokines and Chemokines, (vi) Cellular markers (T regulatory cells, B regulatory cells and dendritic cells) and (vii) In vivo biomarkers (including provocation tests?).
Results
All biomarkers were reviewed in the light of their potential advantages as well as their respective drawbacks. Unmet needs and specific recommendations on all seven domains were addressed.
Conclusions
It is recommended to explore the use of allergen‐specific IgG4 as a biomarker for compliance. sIgE/tIgE and IgE‐FAB are considered as potential surrogate candidate biomarkers. Cytokine/chemokines and cellular reponses provided insight into the mechanisms of AIT. More studies for confirmation and interpretation of the possible association with the clinical response to AIT are needed.
We applied a training and testing approach to develop and validate a plasma metabolite panel for the detection of early-stage pancreatic ductal adenocarcinoma (PDAC) alone and in combination with a ...previously validated protein panel for early-stage PDAC.
A comprehensive metabolomics platform was initially applied to plasmas collected from 20 PDAC cases and 80 controls. Candidate markers were filtered based on a second independent cohort that included nine invasive intraductal papillary mucinous neoplasm cases and 51 benign pancreatic cysts. Blinded validation of the resulting metabolite panel was performed in an independent test cohort consisting of 39 resectable PDAC cases and 82 matched healthy controls. The additive value of combining the metabolite panel with a previously validated protein panel was evaluated.
Five metabolites (acetylspermidine, diacetylspermine, an indole-derivative, and two lysophosphatidylcholines) were selected as a panel based on filtering criteria. A combination rule was developed for distinguishing between PDAC and healthy controls using the Training Set. In the blinded validation study with early-stage PDAC samples and controls, the five metabolites yielded areas under the curve (AUCs) ranging from 0.726 to 0.842, and the combined metabolite model yielded an AUC of 0.892 (95% confidence interval CI = 0.828 to 0.956). Performance was further statistically significantly improved by combining the metabolite panel with a previously validated protein marker panel consisting of CA 19-9, LRG1, and TIMP1 (AUC = 0.924, 95% CI = 0.864 to 0.983, comparison DeLong test one-sided P= .02).
A metabolite panel in combination with CA19-9, TIMP1, and LRG1 exhibited substantially improved performance in the detection of early-stage PDAC compared with a protein panel alone.
Plastics are now found in all natural environments including soil. The effects of microplastics in terrestrial systems, however, remain largely unexplored. Polyethylene is one of the ...mass-manufactured polymers found in terrestrial environments. It is used in many different sectors, for example in agricultural mulches, composite materials, and packaging. The presence of microplastics in soil, including polyethylene, can affect the transport of hydrophobic organic pollutants including pesticides. The objective of this study was to investigate the influence of polyethylene microplastics (<250 μm) on the transport of two selected organic plant-protection agents (atrazine and 4-(2,4-dichlorophenoxy) butyric acid) in soil under different aqueous conditions, using inverse liquid chromatography. The distribution coefficients for the sorbates that were sorbed to pure polyethylene microplastic were found to be significantly smaller than those for the sorbates sorbed to pure soil. The addition of 10% (w/w) polyethylene to the soil therefore led to an overall reduction in sorption, but the sorption trends due to variations in pH and ionic strength were not affected. The results imply that the presence of polyethylene microplastics in soil may therefore increase the mobility of organic contaminants by reducing the sorption capacity of natural soils, which must be validated by further research.
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•The effects of microplastics in terrestrial systems have been largely unexplored.•Sorption of organic plant protection agents by polyethylene microplastics was less affected by variations in pH than sorption by soils.•Effect of ionic strength variations on sorption indicates no cation bridging for polyethylene microplastics.•Polyethylene microplastics reduce soil sorption capacities.
Practical components for three-dimensional molecular nanofabrication must be simple to produce, stereopure, rigid, and adaptable. We report a family of DNA tetrahedra, less than 10 nanometers on a ...side, that can self-assemble in seconds with near-quantitative yield of one diastereomer. They can be connected by programmable DNA linkers. Their triangulated architecture confers structural stability; by compressing a DNA tetrahedron with an atomic force microscope, we have measured the axial compressibility of DNA and observed the buckling of the double helix under high loads.
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