Static condensation method for the reduced dynamic modeling of mechanisms and structures

Archive of Applied Mechanics - In this paper, a novel static condensation method is extended to mechanisms and structures with internal joints. The formulation is framed inside the static reduction...     

Aptamers with Tunable Affinity Enable Single-Molecule Tracking and Localization of Membrane Receptors on Living Cancer Cells

Tumor cell-surface markers are usually overexpressed or mutated protein receptors for which spatiotemporal regulation differs between and within cancers. Single-molecule fluorescence imaging can profile individual markers in different cellular contexts with molecular precision. However, standard single-molecule imaging methods based on overexpressed genetically encoded tags or cumbersome probes can significantly alter the native state of receptors. We introduce a live-cell points accumulation for imaging in nanoscale topography (PAINT) method that exploits aptamers as minimally invasive affinity probes. Localization and tracking of individual receptors are based on stochastic and transient binding between aptamers and their targets. We demonstrated single-molecule imaging of a model tumor marker (EGFR) on a panel of living cancer cells. Affinity to EGFR was finely tuned by rational engineering of aptamer sequences to define receptor motion and/or native receptor density.     

The Systemic Inflammation Index on Admission Predicts In-Hospital Mortality in COVID-19 Patients

Background. The rapid onset of a systemic pro-inflammatory state followed by acute respiratory distress syndrome is the leading cause of mortality in patients with COVID-19. We performed a retrospective observational study to explore the capacity of different complete blood cell count (CBC)-derived inflammation indexes to predict in-hospital mortality in this group. Methods. The neutrophil to lymphocyte ratio (NLR), derived NLR (dNLR), platelet to lymphocyte ratio (PLR), mean platelet volume to platelet ratio (MPR), neutrophil to lymphocyte × platelet ratio (NLPR), monocyte to lymphocyte ratio (MLR), systemic inflammation response index (SIRI), systemic inflammation index (SII), and the aggregate index of systemic inflammation (AISI) were calculated on hospital admission in 119 patients with laboratory confirmed COVID-19. Results. Non-survivors had significantly higher AISI, dNLR, NLPR, NLR, SII, and SIRI values when compared to survivors. Similarly, Kaplan–Meier survival curves showed significantly lower survival in patients with higher AISI, dNLR, MLR, NLPR, NLR, SII, and SIRI. However, after adjusting for confounders, only the SII remained significantly associated with survival (HR = 1.0001; 95% CI, 1.0000–1.0001, p = 0.029) in multivariate Cox regression analysis. Conclusions. The SII on admission independently predicts in-hospital mortality in COVID-19 patients and may assist with early risk stratification in this group.     

A tandem mass spectrometric investigation of the low‐energy collision‐activated fragmentation of neo‐clerodane diterpenes

Mass spectrometric fragmentation data of neo‐clerodane diterpenes are almost inexistent but they can prove helpful for the qualitative and quantitative analysis of these compounds as well as for the identification of unknown compounds belonging to this class of plant secondary metabolites. [M–H]^– ions of nine neo‐clerodane diterpenes (1–9), recently isolated from Teucrium chamaedrys, were generated by electrospray ionization and were fragmented in the collision cell of a Triple Quadrupole (TQ) and of a Quadrupole Ion Trap (QIT) mass spectrometer. The deprotonated neo‐clerodane glucosides, chamaedryoside A and B (1, 2), readily lost the sugar residue to give, as their main fragmentation channel, the neo‐clerodane ions, I and II, which were structurally characterized by TQ and QIT MS. The collision‐activated dissociation (CAD) mass spectra of I and II and of deprotonated neo‐clerodanes 3–9 allowed us to reach some general conclusions on the fragmentation pathways of this class of compounds. For example, teuflin and its OH derivatives, teucrin A, teuflidin and 6‐β‐hydroxyteucridin, showed a characteristic fragmentation pattern involving the loss of 94 Da and 124 Da from the lactone moiety, whereas a loss of 44 Da was observed for teucrin E, and of 58 Da for teucrin F and G. In addition, several compound‐specific fragmentations were observed and can be proposed for the identification of individual compounds. The systematic approach allowed us to hypothesize the mechanisms of the most important collision‐activated dissociation/isomerization channels. Copyright © 2010 John Wiley & Sons, Ltd.     

Quarkonium polarization in pp and p-nucleus collisions

The existing measurements of quarkonium polarization in proton-antiproton and proton-nucleus collisions are puzzling. We highlight issues which are often underestimated in the experimental analyses: the importance of the choice of the experimental acceptance on the comparison between experimental measurements and theoretical calculations. New measurements must provide more detailed information, such that physical conclusions can be derived without relying on model-dependent assumptions. We also describe a frame-invariant formalism which minimizes the dependence of the measurements on the experimental acceptance, facilitates the comparison with theoretical calculations, and probes systematic effects due to experimental biases.     

Physico-Chemical Properties of Inorganic NPs Influence the Absorption Rate of Aquatic Mosses Reducing Cytotoxicity on Intestinal Epithelial Barrier Model

Noble metals nanoparticles (NPs) and metal oxide NPs are widely used in different fields of application and commercial products, exposing living organisms to their potential adverse effects. Recent evidences suggest their presence in the aquifers water and consequently in drinking water. In this work, we have carefully synthesized four types of NPs, namely, silver and gold NPs (Ag NPs and Au NPs) and silica and titanium dioxide NPs (SiO₂ NPs and TiO₂ NPs) having a similar size and negatively charged surfaces. The synthesis of Ag NPs and Au NPs was carried out by colloidal route using silver nitrate (AgNO₃) and tetrachloroauric (III) acid (HAuCl₄) while SiO₂ NPs and TiO₂ NPs were achieved by ternary microemulsion and sol-gel routes, respectively. Once the characterization of NPs was carried out in order to assess their physico-chemical properties, their impact on living cells was studied. We used the human colorectal adenocarcinoma cells (Caco-2), known as the best representative intestinal epithelial barrier model to understand the effects triggered by NPs through ingestion. Then, we moved to explore how water contamination caused by NPs can be lowered by the ability of three species of aquatic moss, namely, Leptodictyum riparium, Vesicularia ferriei, and Taxiphyllum barbieri, to absorb them. The experiments were conducted using two concentrations of NPs (100 μM and 500 Μm as metal content) and two time points (24 h and 48 h), showing a capture rate dependent on the moss species and NPs type. Then, the selected moss species, able to actively capture NPs, appear as a powerful tool capable to purify water from nanostructured materials, and then, to reduce the toxicity associated to the ingestion of contaminated drinking water.