Wyniki wyszukiwania - Biblioteka Nauki

1

Monte Carlo algorithm for drift and diffusion of ions in anisotropic, non-homogeneous media

100%

Stojmenovik G. , Vermael S. , Beunis F. , Neyts K. , Verschueren A. R. M.

Opto-Electronics Review

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2007

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tom Vol. 15, No. 1

13-19

EN

A new Monte Carlo algorithm for ion transport in two-dimensional anisotropic media is reported. It is based on physical considerations of drift and diffusion in anisotropic media with or without an impermeable boundary. Inhomogeneities in the medium and electric field can be taken into account by averaging along the ion trajectory. The algorithm has been appplied to the calculation of ion transport in liquid crystal displays and has been successfully compared with a finite difference program on a one-dimensional liquid crystal structure.

2

The role of magnesium in the supposed mechanism of anaesthesia

88%

Kiss S. A. , Galbacs Z. , Galbacs G.

Journal of Elementology

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2006

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tom 11

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nr 4

EN

The anaesthetic, narcotic effect of magnesium has been discussed since the publication of Meltzer-Auger (1906), but its mechanism has not been clarified. Since then, other investigations have also been performed, but none of the publications has explained the issue. We propose a mechanism analogous to the studies made by Feinstein (1964), who examined organic compounds showing anaesthetic effects. Our view is that magnesium abridges two phospholipids of the opposite sides of the membrane through their phosphate groups. This binding results in membrane rigidity, which makes the ion permeability provided by the ion channel and/or carrier decrease or discontinue, thus the halting of the Na+, K+ and Ca2+ ion flow eventually causes an anaesthetic effect. Another possible pathway is that magnesium ions block the activity of N-methyl-D-aspartate (NMDA) receptor to control the ion channel, which also lowers the permeability of the membrane.

3

The effect of cholinergic receptors on ionic transport in the skin of a frog Rana esculenta L.

88%

Kosik-Bogacka D. , Tyrakowski T.

Zoologica Poloniae

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2001

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tom 46

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nr 1-4

4

The effect of serotonin on epinephrine modulation of transepithelial ion transport in isolated frog skin

88%

Kosik-Bogacka D. I. , Tyrakowski T.

Folia Biologica

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2006

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tom 54

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nr 3-4

5

The effect of adrenergic receptors on ionic transport in the skin of a frog Rana esculenta L.

88%

Kosik-Bogacka D. , Tyrakowski T.

Zoologica Poloniae

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2001

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tom 46

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nr 1-4

6

Status of the Warsaw ECR ion source and injection line

75%

Sudlitz K. , Kulczycka E. , Filipiak B. , Górecki A.

Nukleonika

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2003

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tom Vol. 48,suppl.2

105-108

EN

A room temperature home built 10 GHz ECR ion source delivers beams of B, C, N, O, F, Ne, S, Ar to the Cyclotron U200-P. The same ion source has also been used for surface irradiation of the solids. To upgrade the ion source and increase the ion current in the cyclotron an oven for evaporation of solid materials has been constructed and a two gap buncher has been installed in the injection line. Some new observations on the influence of the extraction system on the ion beam current will be presented.

7

Zastosowanie polimerowych membran inkluzyjnych w procesach transportu jonów metali

75%

Baczyńska M. , Regel-Rosocka M. , Wiśniewski M.

Przemysł Chemiczny

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2013

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tom T. 92, nr 6

928--935

8

Characterization of electrical charge separation at the interface of two aqueous solutions in the presence of concentration gradients and cation/anion mobility ratio asymmetry

75%

Cernescu A. , Luchian T.

Open Physics

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2005

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tom 3

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nr 1

15-24

EN

Physical consequences of ionic diffusion processes play a major role on the outcome of electrophysiology experiments due to both their contribution to the ionic transmembrane transport and phenomena taking place at the measuring instruments interface. As most of the time heterogenities in biological media with respect to ionic diffusion constants are disregarded, we intended to look upon the general case of ionic diffusion at the interface of two liquids on which gradients of these diffusion constants no longer can be neglected. We developed a theoretical model for the diffusion potential which emerges at an aqueous interface under gradients of concentration and diffusion constants. The experimental validation of our model was achieved through potential difference measurements of the diffusion potential between two solutions containing sodium chloride (NaCl) and glycerine solutions of various concentrations. Within the studied domain of the electrical charge mobility ratio, we noticed that experimental results are in agreement with the theoretically inferred diffusion potential values. This demonstrates that the resulting relationship for the diffusion potential inferred from our model could be applied for other cases, as well. When the ionic solutions contains an indefinite quantity of glycerine or an unknown substance able to modify diffusion constants of sodium and chloride, it was shown that through measurements of the diffusion potential one can infer the unknown concentration of glycerine and the modified ionic mobility ratio. This, in turn, builds up the foundation for a novel yet simple and efficient analitycal sensing device for quantitative determination in the field.

9

Luminal hydrochloric acid stimulates rapid transepithelial ion fluxes in rodent esophageal stratified squamous epithelium

75%

Lin B. R. , Hsieh H. T. , Lee J. M. , Lai I. R. , Chen C. F. , Yu L. C. H.

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tom 59

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nr 3

525-542

EN

It remains unclear whether enhanced ion fluxes occur in the esophageal stratified squamous epithelium upon acid exposure. Rat esophageal tissues devoid of submucosal glands displayed basal short-circuit current (Isc) of 5.03 ± 1.93 µA/cm2 and lumen-negative potential difference (PD) in association with net absorption of Na+ and Cl-, and secretion of HCO3-. Luminal hydrochloric acid (HCl) challenge (pH = 1.6) triggered an acute rise of the Isc and increment of negative PD to seven-fold of baseline, which was diminished in HCO3--free, but not Na+- free buffer. The rise of Isc was inhibited by pretreatment with di-isothiocyanatostilbene-2, 2'-disulphonic acid (DIDS) and 5-(N-ethyl-N-isopropyl)-amiloride (EIPA). Topical carbachol, capsaicin, forskolin or CFTRinh-172 had no effect on basal Isc. CFTRinh-172 did not reduce the acid-increased Isc. Functional ablation of capsaicin-sensitive nerves had no effect on the acid-induced Isc. The phenomenon of enhanced ion fluxes upon acid stimulation was confirmed in human esophageal specimens. Our results demonstrated that the mechanism of acid-induced rapid transepithelial ion fluxes is dependent on the presence of bicarbonate ions as well as functional anion transporters and Na+/H+ exchanger, but independent of cystic fibrosis transmembrane conductance regulator (CFTR). The capsaicin-sensitive and muscarinic-dependent nerve pathways did not play roles in the mechanism.

10

Effect of capsaicin and dimethyl sulphoxide [DMSO] on ion transport in isolated skin of frog [Rana esculenta L.]

75%

Kosik- Bogacka D. I. , Tyrakowski T.

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nr 1-2

11

A dynamic model for ion transport in Egeria densa leaf cells

75%

Buschmann P.

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1994

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tom 12

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nr 2

12

Biomimetic polyesters and their role in ion transport across cell membranes

75%

Jedlinski Z. , Kurcok P. , Adamus G. , Juzwa M.

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2000

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tom 47

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nr 1

EN

Syntheses of biomimetic low-molecular weight poly-(R)-3-hydroxybutanoate mediated by three types of supramolecular catalysts are presented. The utility of these synthetic polyesters for preparation of artificial channels in phospholipid bilayers capable of sodium and calcium ion transport across cell membranes, is discussed. Further studies on possible applications of these bio-polymers for manufacturing drugs of prolonged activity are under way.

13

Effect of hibernation on sodium and chloride ion transport in isolated frog skin

75%

Kosik-Bogacka D. I. , Tyrakowski T.

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tom 55

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nr 1-2

14

Locomotory activity and ion transport in the epithelium of terrestrial snails

63%

Tyrakowski T. , Kaczorowski P. , Pawlowicz W. , Ziolkowski M. , Kopczynska E. , Lampka M. , Holynska-Iwan I. , Piskorska E. , Stevesandt M.

Folia Malacologica

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2012

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tom 20

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nr 1

15

Mathematical models of ion transport through cell membrane channels

63%

Miękisz J. , Gomułkiewicz J. , Miękisz S.

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tom Vol. 42, No. 1

39--62

EN

We discuss various models of ion transport through cell membrane channels. Recent experimental data shows that sizes of some ion channels are compared to those of ions and that only few ions may be simultaneously in any single channel. Theoretical description of ion transport in such channels should therefore take into account stochastic fluctuations and interactions between ions and between ions and channel proteins. This is not satisfied by macroscopic continuum models based on the Poisson-Nernst-Planck equations. More realistic descriptions of ion transport are offered by microscopic molecular and Brownian dynamics. We present a derivation of the Poisson-Nernst-Planck equations. We also review some recent models such as single-file diffusion and Markov chains of interacting ions (boundary driven lattice gases). Such models take into account discrete and stochastic nature of ion transport and specifically interactions between ions in ion channels.

PL

W naszej pracy przeglądowej przedstawiamy różne modele transportu jonów w kanałach komórkowych. Rozmiary niektórych kanałów jonowych są rzędu średnicy jonów, a więc tylko kilka jonów może jednocześnie znajdować się w danym kanale. Opis transporu w tak wąskich kanałach powinien brać pod uwagę stochastyczne fluktuacje liczby jonów oraz oddziaływania między nimi. Ciagłe modele makrosko powe oparte na równaniach Poissona-Nernsta-Plancka nie spełniają tych warunków. Bardziej realistyczne modele, takie jak dynamika molekularna i dynamika brownowska, uwzględniają mikroskopową dyskretną strukturę kanałów jonowych. Przed stawiamy wyprowadzenie równań Poissona-Nernsta-Plancka. Przedyskutowujemy również modele łańcuchów Markowa oddziałujących jonów. Modele takie biorą pod uwagę dyskretny charakter transportu jonów i oddziaływania między nimi.

16

Ion transport in rabbit caecum at 12 and 36 months of age

63%

Kosik-Bogacka D. , Tyrakowski T.

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tom 55

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nr 2

117-128

EN

The aim of this study was to investigate the effect of aging on sodium and chloride ions transport in the isolated rabbit coecum. The experiment consisted in measuring PD- transepithelial electrical potential difference mV SM-mechanical stimulation and mechano-sensitivity (dPD) in collected from 12- and 36-month-old rabbits. A modified Ussing system was used for the experiment. Under the incubation in Ringer solution the values of PD and dPD of young rabbit caecum were, respectively, -3.0 ±0.4 mV and -1.2 ±0.3 mV. In 36-month rabbits, on the other hand, the values of these parameters were lower, PD by about 90% whereas dPD by about 83%. Incubation of young rabbits caecum with the presence of amiloride resulted in a reduction of PD by about 17 % and dPD by about 50%, while it did not influence the electrophysiological parameters of caecum in 36-month rabbits. Incubation with bumetanide on young rabbits caecum resulted in PD dropped by about 70% and dPD by about 83%. In the same incubation conditions as those applied for incubation of 36-month rabbits caecum, the level of PD decreased by about 67% while dPD by about 50%. Incubation of young rabbits caecum at the presence of both transport inhibitors resulted in PD decreased by about 87% and dPD by about 83%, whereas that applied for the old rabbits' caecum reduced PD by about 90%, without influencing dPD. Presented data demonstrate that the process of organism ageing inhibits sodium ion transport as well as reduces caecum epithelium sensitivity to mechanical stimuli. Probably, it is a consequence of a reduced with age release of neurotransmitter from sensory terminals; these neurotransmitters modify transepithelial ion transport.

17

Electrochemical gradients across Malpighian tubules of the house cricket, Acheta domesticus, and the mode of action of kinin and CRF-related diuretics

63%

Coast G. M.

Pestycydy

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2009

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nr 1-4

27-32

EN

Double-barrelled ion-selective microelectrodes were used to measure Na+, K+ and Cl- activities in the principal cells of cricket Malpighian tubules, allowing electrochemical gradients across apical and basal membranes to be calculated. At the basal membrane, K+ and Cl- gradients support passive exit into the bathing medium. A thermodynamic analysis shows both ions can be taken up by Na+/K+/2Cl- cotransport driven by a favourable Na+ gradient. At the apical membrane, cations are actively transported into the lumen whereas Cl- moves passively. Evidence is presented to show that diuretic kinins open an apical membrane Cl- conductance whereas Achdo-DH acts via cAMP to stimulate the basal membrane NKCC.

18

Modulation of the endocannabinoid system by the fatty acid amide hydrolase, monoacylglycerol and diacylglycerol lipase inhibitors as an attractive target for secretory diarrhoea therapy

63%

Wasilewski A. , Misicka A. , Sacharczuk M. , Fichna J.

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nr 4

19

Biochemistry of magnesium

63%

Pasternak K. , Kocot J. , Horecka A.

Journal of Elementology

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2010

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tom 15

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nr 3

601-616

EN

Magnesium is essential for biochemical functions of cells. Since Mg2+ has a relatively low ionic radius in proportion to the size of the nucleus (0.86 versus 1.14 f A for Ca2+), it shows exceptional biochemical activity. Due to its physicochemical properties, intracellular magnesium can bind to the nucleus, ribosomes, cell membranes or macromolecules occurring in the cell’s cytosol. It is indispensable for the nucleus to function as a whole and for the maintenance of physical stability as well as aggregation of rybosomes into polysomes able to initiate protein synthesis. Mg2+ can also act as a cofactor for ribonucleic acid enzymes (ribozymes) capable of specifically recognizing and cleaving the target mRNA. As an essential cofactor in NER, BER, MMR processes, Mg2+ is required for the removal of DNA damage. An activator of over 300 different enzymes, magnesium participates in many metabolic processes, such as glycolysis, Krebs cycle, β-oxidation or ion transport across cell membranes. Mg2+ plays a key role in the regulation of functions of mitochondria, including the control of their volume, composition of ions and ATP production.

PL

Magnez jest składnikiem niezbędnym dla zasadniczych funkcji biochemicznych komórki. Ponieważ Mg2+ ma relatywnie mały promień w stosunku do wymiarów jądra (0.86 i 1.14 A odpowiednio dla Mg2+ i Ca2+), wykazuje dużą aktywność biochemiczną. Dzięki właściwościom fizykochemicznym śródkomórkowy Mg2+ może wiązać się z jądrem komórkowym, rybosomami, błonami komórkowymi oraz makromolekułami cytosolu komórki. Magnez jest niezbędny dla funkcjonowania jądra komórkowego jako całości oraz utrzymania fizycznej stabilności i agregacji rybosomów do polisomów zdolnych do biosyntezy białka. Odgrywa on również rolą kofaktora katalitycznych cząsteczek RNA (rybozymów), odpowiedzialnych za specyficzne rozpoznawanie i fragmentację docelowego mRNA. Jako kofaktor w procesach: NER, BER, MMR, przyczynia się do usuwania uszkodzeń DNA. Magnez, będąc aktywatorem ponad 300 różnych enzymów, uczestniczy w przebiegu wielu szlaków metabolicznych, takich jak glikoliza, cykl Krebsa, β-oksydacja czy transport jonów poprzez błony komórkowe. Odgrywa on ponadto bardzo ważną rolę w regulowaniu funkcji mitochondriów, łącznie z regulacją ich wielkości, kompozycją jonów, a także bioenergetyką i regulacją produkcji ATP.

20

The endocrine control of Malpighian tubule secretion: past, present and future

63%

Coast G. M.

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nr 1-2

87-94

EN

Work by Ramsay in the 1950’s established the foundations for our current understanding of primary urine production by Malpighian tubules and we now have detailed knowledge of the epithelial transport processes underlying fluid secretion. Identified neuropeptides and biogenic amines have been shown to stimulate fluid secretion and, for some, detailed information is available on the second messenger pathways and transport processes they activate. There are significant gaps in our knowledge, however, particularly concerning the role of identified diuretics in vivo. The hormonal status of many has yet to be established and it is also unclear whether they are used to control different types of diuresis.