Three-dimensional apoptotic nuclear behavior analyzed by means of field emission in lens scanning electron microscope

Apoptosis is an essential biological function required during embryogenesis, tissue homeostasis, organ development and immune system regulation. It is an active cell death pathway involved in a variety of pathological conditions. During this process cytoskeletal proteins appear damaged and undergo an enzymatic disassembling, leading to formation of apoptotic features. This study was designed to examine the threedimensional chromatin behavior and cytoskeleton involvement, in particular actin re-modeling. HL-60 cells, exposed to hyperthermia, a known apoptotic trigger, were examined by means of a Field Emission in Lens Scanning Electron Microscope (FEISEM). Ultrastructural observations revealed in treated cells the presence of apoptotic patterns after hyperthermia trigger. In particular, three-dimensional apoptotic chromatin rearrangements appeared involving the translocation of filamentous actin from cytoplasm to the nucleus. FEISEM immunogold techniques showed actin labeling and its precise three-dimensional localization in the diffuse chromatin, well separated from the condensed one. The actin presence in dispersed chromatin inside the apoptotic nucleus can be considered an important feature, indispensable to permit the apoptotic machinery evolution

Growth hormone plus resistance exercise attenuate structural changes in rat myotendinous junctions resulting from chronic unloading.

Myotendinous junctions (MTJs) are specialized sites on the muscle surface where forces generated by myofibrils are transmitted across the sarcolemma to the extracellular matrix. At the ultrastructural level, the interface between the sarcolemma and extracellular matrix is highly folded and interdigitated at these junctions. In this study, the effect of exercise and growth hormone (GH) treatments on the changes in MTJ structure that occur during muscle unloading, has been analyzed. Twenty hypophysectomized rats were assigned randomly to one of five groups: ambulatory control, hindlimb unloaded, hindlimb unloaded plus exercise (3 daily bouts of 10 climbs up a ladder with 50% body wt attached to the tail), hindlimb unloaded plus GH (2 daily injections of 1 mg/kg body wt, i.p.), and hindlimb unloaded plus exercise plus GH. MTJs of the plantaris muscle were analyzed by electron microscopy and the contact between muscle and tendon was evaluated using an IL/B ratio, where B is the base and IL is the interface length of MTJ's digit-like processes. After 10 days of unloading, the mean IL/B ratio was significantly lower in unloaded (3.92), unloaded plus exercise (4.18), and unloaded plus GH (5.25) groups than in the ambulatory control (6.39) group. On the opposite, the mean IL/B ratio in the group treated with both exercise and GH (7.3) was similar to control. These findings indicate that the interaction between exercise and GH treatments attenuates the changes in MTJ structure that result from chronic unloading and thus can be used as a countermeasure to these adaptations

Comparison of rheological behaviour of bio-based and synthetic epoxy resins for making ecocomposites

In this paper, the rheological behaviour of a petroleum-based epoxy (EL2 laminating epoxy) was compared with the Super Sap CLR clear bio-resin epoxy. The focus of the work was on the viscous and viscoelastic performance of these epoxy resins. Rheological tests were carried out at 15, 30, and 60 min after the mixing of the pure epoxies and the hardeners at a constant temperature of 25 °C. The results obtained from the rheometer tests showed that the viscosity of both epoxy systems decreased with increasing shear rate, which is typical behaviour of a shear thinning fluid. Regarding the oscillatory rheology tests, the viscoelastic properties of both epoxy resins were studied within their linear viscoelastic region (LVER) by amplitude sweep test, which was also carried out 15, 30, and 60 min after mixing the epoxies with the hardeners. It was noticed that the petroleum-based epoxy possessed a more significant LVER relative to the bio-based resin. Finally, the storage modulus (G′), the loss modulus (G″), and the phase angle were extracted, and these parameters were investigated over low and high frequencies. From the test results, we observed that both epoxy resins showed a liquid-like viscoelastic behaviour due to their phase angle values, which were always between 45° and 90°, and by the general tendency of the G″ predominance over G′ at low and high frequencies

Melatonin prevents chemical-induced Haemopoietic cell death

Melatonin (MEL), a methoxyindole synthesized by the pineal gland, is a powerful antioxidant in tissues as well as within cells, with a fundamental role in ameliorating homeostasis in a number of specific pathologies. It acts both as a direct radical scavenger and by stimulating production/activity of intracellular antioxidant enzymes. In this work, some chemical triggers, with different mechanisms of action, have been chosen to induce cell death in U937 hematopoietic cell line. Cells were pre-treated with 100 μM MEL and then exposed to hydrogen peroxide or staurosporine. Morphological analyses, TUNEL reaction and Orange/PI double staining have been used to recognize ultrastructural apoptotic patterns and to evaluate DNA behavior. Chemical damage and potential MEL anti-apoptotic effects were quantified by means of Tali® Image-Based Cytometer, able to monitor cell viability and apoptotic events. After trigger exposure, chromatin condensation, micronuclei formation and DNA fragmentation have been observed, all suggesting apoptotic cell death. These events underwent a statistically significant decrease in samples pre-treated with MEL. After caspase inhibition and subsequent assessment of cell viability, we demonstrated that apoptosis occurs, at least in part, through the mitochondrial pathway and that MEL interacts at this level to rescue U937 cells from death. © 2014 by the authors; licensee MDPI, Basel, Switzerland

MODELING the INTERACTION BETWEEN AIDS and TUBERCULOSIS

A deterministic model is proposed for the study of the dynamics of acquired immunodeficiency syndrome (AIDS) and tuberculosis (TB) co-infection. the model is comprised by a set of sixteen ordinary differential equations representing different states of both diseases, and it is intended to provide a theoretical framework for the study of the interaction between both infections. Numerical simulations of the model resulted in three striking outcomes: first, the pathogenicity of Human Immunodeficiency Virus (HIV) is enhanced by the presence of TB, and vice-versa; second, the prevalence of AIDS is higher in the presence of TB; and third, relative risk analysis demonstrated a much stronger influence of AIDS on TB than the other way around.ESCOLA PAULISTA MED,BR-04023 São Paulo,BRAZILUNIV São Paulo,INST PHYS,São Paulo,BRAZILHCFMUSP,BR-01246 São Paulo,BRAZILESCOLA PAULISTA MED,BR-04023 São Paulo,BRAZILWeb of Scienc

Modelisation of transition and noble metal vicinal surfaces: energetics, vibrations and stability

The energetics of transition and noble metal (Rh, Pd, Cu) vicinal surfaces, i.e., surface energy, step energy, kink energy and electronic interactions between steps, is studied at 0K from electronic structure calculations in the tight-binding approximation using a {\it s, p} and {\it d} valence orbital basis set. Then, the surface phonon spectra of copper are investigated in the harmonic approximation with the help of a semi-empirical inter-atomic potential. This allows to derive the contribution of phonons at finite temperatures to the step free energy and to the interactions between steps. The last part is devoted to the stability of vicinal surfaces relative to faceting with special attention to the domain of orientations (100)-(111). Semi-empirical potentials are shown to be not realistic enough to give a reliable answer to this problem. The results derived from electronic structure calculations predict a variety of behaviors and, in particular, a possible faceting into two other vicinal orientations. Finally, temperature effects are discussed. Comparisons are made with other theoretical works and available experiments

Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone),on the gelation of aqueous micellar solutions of Pluronic copolymer F127

The micellization of F127 (E98P67E98) in dilute aqueous solutions of polyethylene glycol (PEG6000 and PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic radius (rh,app) obtained from the dynamic light scattering technique increased with increase in PEG concentration but decreased on addition of PVP, results which are consistent with interaction of the micelles with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion was used to determine the onset of gelation. The critical concentration of F127 for gelation increased on addition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scattering (SAXS) was used to show that the 30 wt% F127 gel structure (fcc) was independent of polymer type and concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elastic modulus (G0 max) of 30 wt% F127 decreased from its value for water alone as PEG was added, but was little changed by adding PVP. These results are consistent with the packed-micelles in the 30 wt% F127 gel being effectively isolated from the polymer solution on the microscale while, especially for the PEG, being mixed on the macroscale

Initial investigation of athletes’ electrocardiograms acquired by wearable sensors during the pre-exercise phase

Aim: The aim of this study is to support large-scale prevention programs fighting sport-related sudden cardiac death by providing a set of electrocardiographic features representing a starting point in the development of normal reference values for the pre-exercise phase. Background: In people with underlying, often unknown, cardiovascular abnormalities, increased cardiovascular load during exercise can trigger sport-related sudden cardiac death. Prevention remains the only weapon to contrast sport-related sudden cardiac death. So far, no reference values have been proposed for electrocardiograms of athletes acquired with wearable sensors in the pre-exercise phase, consisting of the few minutes immediately before the beginning of the training session. Objective: To perform an initial investigation of athletes’ electrocardiograms acquired by wearable sensors during the pre-exercise phase. Methods: The analyzed electrocardiograms, acquired through BioHarness 3.0 by Zephyr, belong to 51 athletes (Sport Database and Cycling Database of the Cardiovascular Bioengineering Lab of the Università Politecnica delle Marche, Italy). Preliminary values consist of interquartile ranges of six electrocardiographic features which are heart rate, heart-rate variability, QRS duration, ST level, QT interval, and corrected QT interval. Results: For athletes 35 years old or younger, preliminary values were [72;91]bpm, [26;47]ms, [85;104]ms, [-0.08;0.08]mm, [326;364]ms and [378;422]ms, respectively. For athletes older than 35 years old, preliminary values were [71;94]bpm, [16;65]ms, [85;100]ms, [-0.11;0.07]mm, [330;368]ms and [394;414]ms, respectively. Conclusion: Availability of preliminary reference values could help identify those athletes who, due to electrocardiographic features out of normal ranges, are more likely to develop cardiac complications that may lead to sport-related sudden cardiac death