The Cytotoxic Effect of α-Synuclein Aggregates

Parkinson's disease is a neurodegenerative disorder involving a functional protein, α-synuclein, whose primary function is related to vesicle trafficking. However, α-synuclein is prone to form aggregates, and these inclusions, known as Lewy bodies, are the hallmark of Parkinson's disease. α-synuclein can alter its conformation and acquire aggregating capacity, forming aggregates containing β-sheets. This protein's pathogenic importance is based on its ability to form oligomers that impair synaptic transmission and neuronal function by increasing membrane permeability and altering homeostasis, generating a deleterious effect over cells. First, we establish that oligomers interfere with the mechanical properties of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membrane, as demonstrated by nanoindentation curves. In contrast, nanoindentation revealed that the α-synuclein monomer's presence leads to a much more resistant lipid bilayer. Moreover, the oligomers’ interaction with cell membranes can promote lactate dehydrogenase (LDH) release, suggesting the activation of cytotoxic events.     

Determination of trace level impurities in uranium compounds by ICP-AES after organic extraction

The determination was studied of Al, B, Be, Cd, Ca, Co, Cu, Mg, Mn, Mo, Pb, Si, Sn, V, Cr, Ni, and Fe as trace level impurities in uranium compounds by ICP-AES after extraction of uranium with three different mixtures of di-(2-ethyl-hexyl) phosphate (D2EHP) and tri-(2-ethyl-hexyl)-phosphate (T2EHP) in solvents like toluene, carbon tetrachloride, hexane and cyclohexane. The study was carried out in presence of different concentrations of HCl and HNO(3). A single extraction with D2EHP in cyclohexane using nitric acid as matrix was sufficient to reduce the U(3)O(8) concentration from 100 g/l to 100 microg/ml. The ICP-AES instrumentation applied, allowed the determination of metal concentrations ten-times lower than those usually found in nuclear grade U(3)O(8). To check the efficiency of the extraction and the accuracy of the proposed method, Certified Reference Materials were used in the dissolution and extraction steps. The method described can be used for the determination of trace metals in nuclear grade U(3)O(8).     

The first immobilization of pyridine-bis(oxazoline) chiral ligands

[formula: see text] A chiral pyridine-bis(oxazoline) ligand, functionalized with a vinyl group in the pyridine ring, can be polymerized with styrene and divinylbenzene to obtain supported chiral ligands. As proof of the usefulness of this supported ligands, the corresponding ruthenium complexes are catalysts for the cyclopropanation reaction of styrene with ethyl diazoacetate with up to 85% ee.     

Wasserstoffbrücken in 1,1‐Bis(2‐hydroxyethyl)‐3‐benzoylthioharnstoff und seinen Nickel(II)‐ und Kupfer(II)‐Chelat‐Komplexen

Hydrogen Bonds in 1,1‐Bis(2‐hydroxyethyl)‐3‐benzoylthiourea and its Nickel(II)‐ and Copper(II)‐Chelate Complexes The ligand 1,1‐bis(2‐hydroxyethyl)‐3‐benzoylthiourea HL, ( 1 ), yields with nickel(II) and copper(II) ions neutral complexes [NiL₂], ( 2 ), and [CuL₂], ( 3 ). By X‐ray structure analysis and IR spectroscopy different intramolecular hydrogen bonds (OH…O) and (OH…N) could be identified in both equally coordinated ligands of the [NiL₂] molecule. For comparison X‐ray and IR data were also estimated for 1 and 3 .     

Adsorption and Desorption of the Herbicide Thiazafluron as A Function of Soil Properties

Abstract

The effect of soil composition on the adsorption and desorption of the herbicide thiazafluron [1.3-dimethyl-1-(5-trifluoromethyl-1,2,3-thiadiazol-2-yl) urea] by 20 soil samples of 13 selected soil profiles of southern Spain has been studied. The adsorption curves conformed the Freundlich equation and the values of the constants, Kf and nf, ranged from 0.13 to 4.64 and from 0.14 to 1.30, respectively. The simple and multiple regression analysis between Kf and soil properties revealed soil clay content, illite content and CEC as fundamental factors determining thiazafluron adsorption by soils. Unlike other substituted ureas, non significant correlation was found with soil organic matter. Desorption of thiazafluron was hysteretic in all cases, showing and values much lower than those for adsorption. Desorption kinetic indicated that this hysteresis is essentially due to irreversible adsorption, although some degradation seems also to occur. The Freundlich desorption Kfd values were closely related to the same factors as Kf: clay and illite contents and also montmorillonite content, suggesting that most of the hysteresis was due to thiazafluron irreversibly bound to soil clay mineral components.     

Continental and Antarctic Lichens: isolation,identification and molecular modeling of the depside tenuiorin from the Antarctic lichen Umbilicaria antarctica as tau protein inhibitor

Abstract

Alzheimer´s disease (AD) is the most common form of dementia involving Aβ and tau protein. So far, AD cure remains elusive, but considering that AD progresses throughout tau pathology, which turns tau protein an appropriate target, besides tau is also included in other neurodegenerative disorders named as tauopathies. Here, we have isolated seventeen compounds belonging to six lichens species. Due to scarce of spectroscopic data of the compound 5,7-dihydroxy-6-methylphthalide, we explained their structural elucidation based on NMR data. In this study, we show that only tenuiorin from Umbilicaria antarctica inhibited 50% of tau 4R at 100?µM. Then, we shown that molecular interactions of tenuiorin with the steric zipper model of the hexapeptide ³⁰⁶VQIVYK³¹¹ were studied by docking calculations and the results suggested that tenuiorin forms both hydrogen bonds with lysine and glutamine side chains and forms several hydrophobic interactions with valine and lysine from ³⁰⁶VQIVYK³¹¹ motif.     

Thermomechanical treatment of two Ecuadorian zeolite-rich tuffs and their potential usage as supplementary cementitious materials

Two Ecuadorian zeolite-rich tuffs, coded as Zeo1 (Mordenite) and Zeo2 (Clinoptilolite–Heulandite–Mordenite), were treated and used as supplementary cementitious materials (SCM) so as to study the effect of the thermal and mechanical treatments on pozzolanic reaction in mortars. The treatment was carried out by means of thermomechanical process according to a central composite-blocked cube-star experimental design. In this experimental design as independent factors the milling time (48, 60, 90, 120 and 132 min) and the heating temperatures (559, 600, 700, 800 and 841 °C) were used but keeping a constant heating time (5 h), and zeolite-rich tuffs as experimental blocks. The proportion of SCM was kept constant i.e. 15 %. On the other hand, the compressive strength, fixed lime, normalized water in hydrates and mg Ca(OH)₂ per mg Cement at 7, 28 and 45 days, as well as hydration products related to dehydration degree of the zeolitic tuffs (DOD) were used as dependent factors. In addition, Quantitative and High-temperature chamber XRD, TG-DSC, particle size distribution and SEM-EDS were also carried out. The most significant factor was calcination leading to increase in the compressive strength compared to control, but just up to 800 °C because of recrystallization. As a conclusion, a meaningful loss of crystal structure of zeolites was not observed; but instead, the treatment could only lead to removing the water in cages and voids, thus improving the reaction with Ca(OH)₂, producing more hydrates. In addition, lime was not only fixed by pozzolanic reaction, but also by carbonation.     

Effects of the cryopreservation procedures on recovered rice cell populations

Cryogenic storage of plant cells allows the long-term maintenance of valuable genotypes. Cryopreservation of calli and cell suspensions is often performed using cryoprotectants and slow cooling rates. Rice calli (Oryza sativa L.) were cryopreserved by this procedure as well as by direct immersion in liquid nitrogen without cryoprotection. Subsequently, the characteristics of the recovered cells as well as the effects of putative cryoselection were investigated by microscopic observations and flow cytometric analyses. For this purpose, protoplasts were prepared from calli that had been cryopreserved by direct plunging into liquid nitrogen and from their unfrozen controls. Results show that direct immersion in liquid nitrogen of calli pre-treated with abscisic acid is a fast and highly efficient freezing procedure that maintains the main characteristics of the cell populations and appears to increase their metabolic activity