Zerumbone Inhibits Helicobacter pylori Urease Activity

Helicobacter pylori (H. pylori) produces urease in order to improve its settlement and growth in the human gastric epithelium. Urease inhibitors likely represent potentially powerful therapeutics for treating H. pylori; however, their instability and toxicity have proven problematic in human clinical trials. In this study, we investigate the ability of a natural compound extracted from Zingiber zerumbet Smith, zerumbone, to inhibit the urease activity of H. pylori by formation of urease dimers, trimers, or tetramers. As an oxygen atom possesses stronger electronegativity than the first carbon atom bonded to it, in the zerumbone structure, the neighboring second carbon atom shows a relatively negative charge (δ−) and the next carbon atom shows a positive charge (δ+), sequentially. Due to this electrical gradient, it is possible that H. pylori urease with its negative charges (such as thiol radicals) might bind to the β-position carbon of zerumbone. Our results show that zerumbone dimerized, trimerized, or tetramerized with both H. pylori urease A and urease B molecules, and that this formation of complex inhibited H. pylori urease activity. Although zerumbone did not affect either gene transcription or the protein expression of urease A and urease B, our study demonstrated that zerumbone could effectively dimerize with both urease molecules and caused significant functional inhibition of urease activity. In short, our findings suggest that zerumbone may be an effective H. pylori urease inhibitor that may be suitable for therapeutic use in humans.

A Note on the Consequences of a Hot Mitochondrion: Some Recent Developments and Open Questions

Background: Chrétien and co-workers (PLOS Biology. 2018;16(1):e2003992) recently suggested that the mitochondrion might possibly be hotter than its surrounding (by as much as 10°C). Objectives: To examine the validity of this claim and review the possible implications and repercussion of such a claim – if true – on some aspects of mitochondrial biochemistry and biophysics. Results: Both the chemical gradient and the electrical gradient Gibbs energy terms in the central equation of chemiosmotic theory are temperature dependent, the first explicitly and the second implicitly. A hotter mitochondrion – as claimed – would imply a 3% correction in the chemical gradient term, but we cannot estimate the corresponding effect on the electrical term at this time since the functional dependence of the voltage on the temperature is not known to the best of the authors’ knowledge. Further, if this claim is true and to the extent claimed (10°C), this may imply some heat-engine character for mitochondrial thermodynamic operation albeit this may only represent 4% at most. Conclusions: Doubts and criticisms regarding the suggestion of a hotter mitochondrion have been raised and are briefly discussed. These doubts are contrasted with some data and considerations that support the claim of a hotter mitochondrion. It is concluded that the mitochondrion is probably hotter than its environment but not to the extent claimed by Chrétien et al. and that the thermodynamic efficiency and the mode of operation of the mitochondrion as an electrochemical battery are very slightly perturbed by even the maximum claimed revision of the temperature of its operation.

Mathematical Model for Secondary Transport of Cations at the Root of Plants

A mathematical expression to describe cation absorption of root is expressed with simulation results. The root cells selectively emit H+ ions with active transport consuming ATPs to establish electrical gradient. The gradient promotes external positive ions to flow into the roots, while carries negatively charged particles with symport. In this paper, a mathematical model whose independent variables are the concentrations of external and internal cation is presented. This differential equation is induced from Ohm’s law. The equation has terms for plant physiology, ion’s physical and electrical properties, growth of plant, and interaction between the root and the surroundings. Simulation showed that the physiology-related coefficient has important role on nutrition absorption.

Characterizations of electrode geometrical shape for dielectrophoresis

<p>This paper presents a characterization of geometrical shape on dielectrophoresis by determining and analysing the geometrical shape of electrodes. The structure or geometrical shape of dielectrophoresis electrode is design using COMSOL software to determine the maximum trapping efficiency of particles. The trapping efficiency of particles can be evaluated by analysing the best electrical gradient and investigated the behaviour of the particles if the existence of a non-uniform electric field. There are three geometrical shapes have been designed which is, peel chain shape, castle wall shape and comb shape. Each of the geometrical shapes have different magnetic field produce, hence each of the design have specific application. Furthermore, these three designed are analysed by varying the material of the electrode for the best trapping efficiency. From the various and previous study, for maximum trapping efficiency the shape used is peel chain shape which is suitable for biological and non-biological particles separation. But for the castle wall and comb shape is the most suitable for biological particles such as red blood cell and bacteria trapping. As for the result obtain, it is proven that peel chain shape could achieve maximum electrical gradient to trap biological or non-biological particles in the future.</p>

On the oxidative damage by cadmium to kidney mitochondrial functions

In the kidney, the accumulation of heavy metals such as Cd2+ produces mitochondrial dysfunctions, i.e., uncoupling of the oxidative phosphorylation, inhibition of the electron transport through the respiratory chain, and collapse of the transmembrane electrical gradient. This derangement may be due to the fact that Cd2+ induces the transition of membrane permeability from selective to nonselective via the opening of a transmembrane pore. In fact, Cd2+ produces this injury through the stimulation of oxygen-derived radical generation, inducing oxidative stress. Several molecules have been used to avoid or even reverse Cd2+-induced mitochondrial injury, for instance, cyclosporin A, resveratrol, dithiocarbamates, and even EDTA. The aim of this study was to explore the possibility that the antioxidant tamoxifen could protect mitochondria from the deleterious effects of Cd2+. Our results indicate that the addition of 1 μmol/L Cd2+ to mitochondria collapsed the transmembrane electrical gradient, induced the release of cytochrome c, and increased both the generation of H2O2 and the oxidative damage to mitochondrial DNA (among other measured parameters). Of interest, these mitochondrial dysfunctions were ameliorated after the addition of tamoxifen.

Application of electrokinetic in controlling heavy metals migration in sand: A feasibility study

Uncontrolled migration of heavy metals from human activities in the subsurface can lead to the degradation of environmental quality and potential use of soil and groundwater. This paper studies the feasibility of using electrokinetics in controlling the migration of heavy metals in sand. Copper and iron (initial concentration of 100 mgL-1) are the target heavy metals in this study as they are the most commonly found heavy metals from human activities such as mining and land filling. The performance of electrokinetic in controlling the migration of these heavy metals is tested in a sand tank at combination of water velocity and electrical gradient of 1.3 cm h-1, 0.5 V cm-1 and 0.88 cm h-1, 1 V cm-1, respectively. The formation of gas at electrodes, scouring on carbon anode and corrosion of crocodile clips during experiment (0.88 cm h-1, 1 V cm-1) showed the occurrence of electrokinetics. Further studies need to be conducted to optimize the operating conditions for effective application of electrokinetic in controlling heavy metals migration in sand.