scholarly journals Wnt11 patterns a myocardial electrical gradient through regulation of the L-type Ca2+ channel

Nature ◽  
2010 ◽  
Vol 466 (7308) ◽  
pp. 874-878 ◽  
Author(s):  
Daniela Panáková ◽  
Andreas A. Werdich ◽  
Calum A. MacRae
Keyword(s):  
Electrical Gradient

scholarly journals Zerumbone Inhibits Helicobacter pylori Urease Activity

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2663
Author(s):  
Hyun Jun Woo ◽  
Ji Yeong Yang ◽  
Pyeongjae Lee ◽  
Jong-Bae Kim ◽  
Sa-Hyun Kim
Keyword(s):  
Helicobacter Pylori ◽  
Carbon Atom ◽  
Natural Compound ◽  
Urease Activity ◽  
Negative Charge ◽  
Positive Charge ◽  
Gastric Epithelium ◽  
Functional Inhibition ◽  
Electrical Gradient ◽  
H Pylori

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.

scholarly journals Calcite Precipitation at Cement–Bentonite Interface. Part 2: Accelera-tion of Transport by an Electrical Gradient

2021 ◽  
Vol 19 (5) ◽  
pp. 447-461
Author(s):  
Kenichiro Nakarai ◽  
Masaki Watanabe ◽  
Kiyoshi Koibuchi ◽  
Georg Kosakowski
Keyword(s):  
Calcite Precipitation ◽  
Electrical Gradient

Effects of ganglion extracts on chloride-dependent electrical potentials and short-circuit currents across the mantle epithelium of Achatina fulica

1987 ◽  
Vol 65 (9) ◽  
pp. 2272-2275
Author(s):  
O. Enyikwola
Keyword(s):  
Cyclic Amp ◽  
Short Circuit ◽  
Achatina Fulica ◽  
Dibutyryl Cyclic Amp ◽  
Prolonged Heating ◽  
Electrogenic Transport ◽  
Electrical Potentials ◽  
Electrical Gradient ◽  
Short Circuit Currents

The left parietal and visceral ganglia of the giant African snail, Achatina fulica, and also nerves leading from them contain a compound that stimulates chloride-dependent electrogenesis by the mantle epithelium. Release of the substance in vitro is stimulated by 5–12 mM K+, provided Ca2+ is present. The active substance is inactivated by trypsin and prolonged heating, but not by brief heating or lipase. The electrical gradient was unaffected by adrenaline, acetylcholine, cyclic AMP, dibutyryl cyclic AMP, 5-hydroxytryptamine, or thyrotropin releasing factor. However, theophylline inhibited electrogenesis. It is suggested that the electrogenic transport of chloride by the mantle of Achatina may be under neuroendocrine control.

Sodium-dependent lysine flux across bullfrog alveolar epithelium

1988 ◽  
Vol 65 (4) ◽  
pp. 1655-1661 ◽  
Author(s):  
K. J. Kim ◽  
E. D. Crandall
Keyword(s):  
Amino Acid ◽  
Opposite Direction ◽  
Ussing Chamber ◽  
Alveolar Epithelium ◽  
Epithelial Barrier ◽  
Alveolar Epithelial ◽  
Control Value ◽  
Electrical Gradient ◽  
Upstream Reservoir ◽  
Net Flux

Amino acid transport across the alveolar epithelial barrier was studied by measuring radiolabeled lysine fluxes across bullfrog lungs in an Ussing chamber. In the absence of a transmural electrical gradient, L-[14C]lysine was instilled into the upstream reservoir and the rate of appearance of the radiolabel in the downstream reservoir was determined. Two lungs from the same animal were used simultaneously to determine tracer fluxes both into and out of the alveolar bath. Results showed that the radiolabel flux measured in the alveolar to the pleural direction was greater than that measured in the opposite direction in the presence of sodium in the bathing fluids. The net flux of L-[14C]lysine was saturable with [Na+], with an apparent transport coefficient (Kt) of 28 mM for Na+. Hill analysis of [14C]lysine flux vs. [Na+] indicated a coupling ratio of 1:1 between sodium and radiolabeled L-lysine. Total L-lysine flux as a function of [L-lysine] was also saturable, with Kt of 7.3 mM for L-lysine. Ouabain significantly decreased absorptive (alveolar-to-pleural) radiolabel flux, while slightly increasing the flux observed in the opposite direction. L-leucine completely inhibited absorptive net flux of L-[14C]lysine. alpha-Methylaminoisobutyric acid (MeAIB), on the other hand, only slightly reduced net flux of L-[14C]lysine from the control value. The presence of a net absorptive, Na+-dependent amino acid flux across the alveolar epithelial barrier indicates that the tissue is capable of removing amino acids and sodium from the alveolar fluid by a coupled cotransport mechanism, which may be important for both protein metabolism and fluid balance by alveolar epithelium.

scholarly journals Characterizations of electrode geometrical shape for dielectrophoresis

2019 ◽  
Vol 15 (2) ◽  
pp. 671
Author(s):  
N. Burham ◽  
A. A. M. Shahar ◽  
A. A. Aziz ◽  
T. N. T. Yaakub ◽  
N. Khairuddin
Keyword(s):  
Magnetic Field ◽  
Blood Cell ◽  
Trapping Efficiency ◽  
Uniform Electric Field ◽  
Geometrical Shape ◽  
Biological Particles ◽  
Geometrical Shapes ◽  
Electrical Gradient ◽  
Is Design

<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>

scholarly journals Secretion by the Malpighian tubules of Rhodnius prolixus stal: electrical events

1984 ◽  
Vol 110 (1) ◽  
pp. 275-290 ◽  
Author(s):  
M. J. O'Donnell ◽  
S. H. Maddrell
Keyword(s):  
Apical Membrane ◽  
Electrical Response ◽  
Basal Membrane ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Chloride Permeability ◽  
Bathing Medium ◽  
Before And After ◽  
Electrical Gradient ◽  
Cation Pump

Transepithelial and intracellular potentials have been simultaneously recorded from Rhodnius upper Malpighian tubules before and after stimulation of fluid secretion. The transepithelial electrical response to the diuretic hormone mimic 5-hydroxytryptamine (5-HT) was triphasic; recordings of intracellular potential changes indicated that the three phases represented successive events at the apical membrane. Depolarizations produced by increasing the bathing medium potassium concentration indicated that the basal membrane was much more permeable to potassium than to sodium. Electrical responses to chloride-free saline were inconsistent with a significant basal membrane chloride permeability. Chloride movements across the basal membrane were opposed by an electrical gradient of about 65 mV. The results of experiments in which tubules were exposed to chloride-free saline or sodium-free saline suggested that chloride entry into the cells was linked to the entry of Na+ and K+. The effects of furosemide and bumetanide upon secretion and potential changes suggested that chloride crossed the basal membrane through co-transport with Na+ and K+. Chloride probably crosses the apical membrane into the lumen passively in response to a favourable electrical gradient of about 35 mV. Cations must be actively pumped into the lumen against an electrical gradient of 35 mV. Our results support previous evidence for an apical cation pump which actively transports Na and K into the lumen. A tentative model of ionic movements during fluid secretion is presented. It is suggested that the apical cation pump maintains sodium at low intracellular concentrations, thereby maintaining a favourable gradient for entry of Na+ through the proposed basal co-transport step. The suggested stoichiometry is Na+:K+:2 Cl-.

Glucocorticoid inhibition of Na-SO4 transport by chick renal brush-border membranes

1989 ◽  
Vol 256 (6) ◽  
pp. R1176-R1183 ◽  
Author(s):  
J. L. Renfro ◽  
N. B. Clark ◽  
R. E. Metts ◽  
M. A. Lynch
Keyword(s):  
Brush Border ◽  
Renal Tubule ◽  
Hormone Treatment ◽  
Sulfate Transport ◽  
Dexamethasone Treatment ◽  
Glucocorticoid Treatment ◽  
Renal Brush Border Membranes ◽  
Electrical Gradient ◽  
22Na Uptake ◽  
Renal Brush Border

To examine the effect of glucocorticoids on sulfate transport by the chick (domestic Gallus gallus) renal tubule we dosed 3-wk-old animals with 60 micrograms dexamethasone/100 g body wt at 24 and 6 h before isolation of renal brush-border (BBM) and basolateral membranes (BLM). Dexamethasone treatment significantly reduced Na-dependent sulfate transport by BBM and had no effect in paired membranes on bicarbonate, proton, or electrical gradient-driven sulfate transport. The glucocorticoid treatment had no statistically significant effect on HCO3-SO4 exchange in the BLM. Kinetic analysis of the dexamethasone effect on the Na-SO4 transport process showed that apparent Vmax was significantly decreased to almost one-half that seen in controls (from 676 to 348 pmol.mg protein-1.5 s-1). The Km in control BBM was 0.40 +/- 0.095 mM and was not significantly different in dexamethasone-treated membranes (0.53 +/- 0.094 mM). To determine whether the dexamethasone-induced decrease in Na-SO4 transport by BBM was indirectly caused by stimulation of Na-H exchange and more rapid dissipation of the initial Na gradient used to drive sulfate uptake, we examined the effect of 0.1 mM amiloride on Na-SO4 uptake by BBM. With amiloride present, dexamethasone treatment caused Vmax to significantly drop from 1,102 to 660 pmol.mg protein-1.5 s-1. Amiloride had no statistically significant effect on the Km. The extent to which amiloride increased Na-SO4 transport and blocked 22Na uptake by BBM did not appear to be related to hormone treatment. The data indicate that glucocorticoids may participate in the regulation of sulfate excretion.

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