Document Server@UHasselt
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Repository of the University of Hasselt containing publications in the fields of statistics, computer science, information strategies and material from the Institute for behavioural sciences.
Mostrando recursos 1 - 20 de 37
1.
Probing diffusion laws within cellular membranes by Z-scan fluorescence correlation spectroscopy - Humpolickova, J.; GIELEN, Ellen; Benda, A.; Fagulova, V.; VAN DE VEN, Martin; Hof, M.; AMELOOT, Marcel; Engelborghs, Y.
The plasma membrane of various mammalian cell types is heterogeneous in structure and may contain microdomains, which can impose constraints on the lateral diffusion of its constituents. Fluorescence correlation spectroscopy (FCS) can be used to investigate the dynamic properties of the plasma membrane of living cells. Very recently, Wawrezinieck et al. (Wawrezinieck, L., H. Rigneault, D. Marguet, and P. F. Lenne. 2005. Biophys. J. 89:4029-4042) described a method to probe the nature of the lateral microheterogeneities of the membrane by varying the beam size in the FCS instrument. The dependence of the width of the autocorrelation function at half-maximum, i.e.,...
2.
Mechanisms for picrotoxin block of alpha(2) homomeric glycine receptors - Wang, D.S.; Mangin, J.M.; Moonen, G; RIGO, Jean-Michel; Legendre, P
It is well known that the convulsant alkaloid picrotoxin (PTX) can inhibit neuronal gamma-aminobutyric acid ( GABA) and homomeric glycine receptors (GlyR). However, the mechanism for PTX block of alpha(2) homomeric GlyR is still unclear compared with that of alpha(1) homomeric GlyR, GABA(A), and GABA(C) receptors. Furthermore, PTX effects on GlyR kinetics have been poorly explored at the single-channel level. Hence, we used the patch-clamp technique in the outside-out configuration to investigate the mechanism of PTX suppression of currents carried by alpha(2) homomeric GlyRs stably transfected into Chinese hamster ovary cells. PTX inhibited the alpha(2) homomeric GlyR current elicited by...
3.
Frequency-dependent modulation of glycine receptor activation recorded from the zebrafish larvae hindbrain - RIGO, Jean-Michel; Legendre, P
In vertebrates, most glycinergic inhibitory neurons discharge phasically at a relatively low frequency. Such a pattern of glycine liberation from presynaptic terminals may affect the kinetics of post-synaptic glycine receptors. To examine this influence, we have analyzed the behavior of glycine receptors in response to repetitive stimulation at frequencies at which consecutive outside-out currents did not superimpose (0.5-4 Hz). Neurotransmitter release was mimicked on outside-out patches from zebrafish hindbrain Mauthner cells using fast flow application techniques. The amplitude of outside-out currents evoked by short (1 ms) repetitive applications of a saturating concentration (3 mM) of glycine remained unchanged for application...
4.
Rafts in oligodendrocytes: Evidence and structure-function relationship - GIELEN, Ellen; Baron, W; Vandeven, M; STEELS, Paul; Hoekstra, D; AMELOOT, Marcel
The plasma membrane of eukaryotic cells exhibits lateral inhomogeneities, mainly containing cholesterol and sphingomyelin, which provide liquid-ordered microdomains (lipid "rafts") that segregate membrane components. Rafts are thought to modulate the biological functions of molecules that become associated with them, and as such, they appear to be involved in a variety of processes, including signal transduction, membrane sorting, cell adhesion and pathogen entry. Although still a matter of ongoing debate, evidence in favor of the presence of these microdomains is gradually accumulating but a consensus on issues like their size, lifetime, composition, and biological significance has yet to be reached. Here,...
5.
Membrane cholesterol extraction decreases Na+ transport in A6 renal epithelia - Balut, C; STEELS, Paul; Radu, M; AMELOOT, Marcel; VAN DRIESSCHE, Willy; JANS, Danny
In this study, we have investigaed the dependence of Na+ transport regulation on membrane cholesterol content in A6 renal epithelia. We continuously monitored short-circuit current (I-SC), transepithelial conductance (G(T)), and transepithelial capacitance (CT) to evaluate the effects of cholesterol extraction from the apical and basolateral membranes in steady-state conditions and during activation with hyposmotic shock, oxytocin, and adenosine. Cholesterol extraction was achieved by perfusing the epithelia with methyl-beta-cyclodextrin (m beta CD) for 1 h. In steady-state conditions, apical membrane cholesterol extraction did not significantly affect the electrophysiological parameters; in contrast, marked reductions were observed during basolateral m beta CD treatment....
6.
Study of the interaction of antiplasmodial strychnine derivatives with the glycine receptor - Philippe, G; Nguyen, L; Angenot, L; Frederich, M; Moonen, G; Tits, M; RIGO, Jean-Michel
Strychnos icaja Baill. (Loganiaccae) is a liana found in Central Africa known to be an arrow and ordeal poison but also used by traditional medicine to treat malaria. Recently, many dimeric or trimeric indolomonoterpenic alkaloids with antiplasmodial properties have been isolated from its rootbark. Since these alkaloids are derivatives of strychnine, it was important, in view of their potential use as antimalarial drugs, to assess their possible convulsant strychnine-like properties. In that regard, their interaction with the strychnine-sensitive glycine receptor was investigated by whole-cell patch-clamp recordings on glycine-gated currents in mouse spinal cord neurons in culture and by [H-3]strychnine competition...
7.
Compartmental Modeling Of The Fluorescence Anisotropy Decay Of A Cylindrically Symmetric Brownian Rotor: Identifiability Analysis. - Boens, N.; Novikov, E.; AMELOOT, Marcel
We present the results of the deterministic identifiability analysis based on similarity transformation for models of one-state excited-state events of cylindrically symmetric rotors in isotropic environments undergoing rotational diffusion described by Brownian reorientation. Such an analysis on error-free time-resolved fluorescence (anisotropy) data can reveal whether the parameters of the considered model can be determined. The fluorescence -response functions I||(t) and I(t), for fluorescence polarized respectively parallel and perpendicular to the electric vector of linearly polarized excitation, are used to construct, in convenient matrix form, expressions of the sum S(t)=I||(t)+2 I(t), the difference D(t)=I||(t)-I(t), and the time-resolved fluorescence anisotropy r(t)=D(t)/S(t). The...
8.
Compartmental modeling and identifiability analysis in photophysics: Review - Boens, N.; AMELOOT, Marcel
The main objective of this review is to show how the concepts of compartmental modeling can be introduced and applied in photophysics. The term "compartment" in a photophysical context is defined as a subsystem composed of a distinct type of species that acts kinetically in a unique way. Compartments can be divided into groundstate and excited-state compartments, depending on the state of the composing species. In photophysics, a compartmental system is perturbed by a light pulse (photo-excitation), and its dynamics is followed via fluorescence within the time range from picoseconds to several hundred nanoseconds. In this review, we present the...
9.
Two-dimensional Forster resonance energy transfer (2-D FRET) and the membrane raft hypothesis - Acasandrei, M.; Dale, R.; VAN DE VEN, Martin; AMELOOT, Marcel
A model for analyzing Forster resonance energy transfer (FRET) data in relation to the cell plasma membrane raft hypothesis is developed to take into account: (a) the distribution of FRET donors and acceptors at the surface of probing antibody fragments specific for a putative raft component; (b) partitioning of the raft component between raft and non-raft areas of the membrane; and (c) the dependence of the raft partition on the expression level of the considered component. Analysis of relevant FRET data in the literature according to this model provides support for the raft hypothesis.
10.
Recovery of regional but not global contractile function by the direct intramyocardial autologous bone marrow transplantation - Results from a randomized controlled clinical trial - HENDRIKX, Marc; Hensen, K.; Clijsters, C.; Jongen, H.; KONINCKX, Remco; Bijnens, E.; Ingels, M.; Jacobs, A.; Geukens, R.; Dendale, P.; Vijgen, J.; Dilling, D.; STEELS, Paul; Mees, U.; Rummens, J.L.
Background-Recent trials have shown that intracoronary infusion of bone marrow cells (BMCs) improves functional recovery after acute myocardial infarction. However, whether this treatment is effective in heart failure as a consequence of remodeling after organized infarcts remains unclear. In this randomized trial, we assessed the hypothesis that direct intramyocardial injection of autologous mononuclear bone marrow cells during coronary artery bypass graft (CABG) could improve global and regional left ventricular ejection fraction (LVEF) at 4-month follow-up. Methods and Results-Twenty patients (age 64.8 +/- 8.7; 17 male, 3 female) with a postinfarction nonviable scar, as assessed by thallium (Tl) scintigraphy and cardiac...
12.
Cross-talk between ATP-regulated K+ channels and Na+ transport via cellular metabolism in frog skin principal cells - Urbach, V; VAN KERKHOVE, Emmy; Maguire, D; Harvey, BJ
Isolated frog skin epithelium, mounted in an Ussing chamber and bathed in standard NaCl Ringer solution, recycles K+ across the basolateral membrane of principal cells through an inward-rectifier K+ channel (Kir) operating in parallel with a Na+-K+-ATPase pump. Here we report on the metabolic control of the Kir channel using patch clamping, short-circuit current measurement and enzymatic determination of cellular (ATP (ATPi). 2. The constitutively active Kir channel in the basolateral membrane has the characteristics of an ATP-regulated K+ channel and is now classed as a KATP channel. In excised inside-out patches the open probability (Po) of KATP channels was...
14.
Beta-carbolines induce apoptosis in cultured cerebellar cyranule neurons via the mitochondrial pathway - Hans, G.; Malgrange, B.; Lallemend, F.; Crommen, J.; Wislet-Gendebien, S.; Belachew, S.; RIGO, Jean-Michel; Robe, P.; Rogister, B.; Moonen, G.
N-Butyl-beta-carboline-3-carboxylate (betaCCB) is, together with 2-methyl-norharmanium and 2,9-dimethylnorharmanium ions, an endogenously occurring beta-carboline. Due to their structural similarities with the synthetic neurotoxin 1-methy14-phenyl-1,2,3,6-tetrahydropyridine (MPTP), harman and norharman compounds have been proposed to be involved in the pathogenesis of Parkinson's disease. While also structurally related, betaCCB has received much less interest in that respect although we had previously demonstrated that it induces the apoptotic cell death of cultured cerebellar granule neurons (CGNs). Herein, we have investigated the molecular events leading to CGN apoptosis upon betaCCB treatment. We first demonstrated that betaCCB-induced apoptosis occurs in neurons only, most likely as a consequence...
15.
Developmental regulation of beta-carboline-induced inhibition of glycine-evoked responses depends on glycine receptor beta subunit expression - MANGIN, Jean-Marie; Nguyen, L.; Gougnard, C.; Rogister, B.; Belachew, S.; Moonen, G.; RIGO, Jean-Michel
In this work, we show that beta-carbolines, which are known negative allosteric modulators of GABA A receptors, inhibit glycine-induced currents of embryonic mouse spinal cord and hippocampal neurons. In both cell types, beta-carboline-induced inhibition of glycine receptor (GlyR)-mediated responses decreases with time in culture. Single-channel recordings show that the major conductance levels of GlyR unitary currents shifts from high levels (>= 50 pS) in 2 to 3 days in vitro (DIV) neurons to low levels (< 50 pS) in 11 to 14 DIV neurons, assessing the replacement of functional homomeric GlyR by heteromeric GlyR. In cultured spinal cord neurons, the...
16.
Peripheral benzodiazepine receptor (PBR) ligand cytotoxicity unrelated to PBR expression - Hans, G.; Wislet-Gendebien, S.; Lallemend, F.; Robe, P.; Rogister, B.; Belachew, S.; Nguyen, L.; Malgrange, B.; Moonen, G.; RIGO, Jean-Michel
Some synthetic ligands of the peripheral-type benzodiazepine receptor (PBR), an 18 kDa protein of the outer mitochondrial membrane, are cytotoxic for several tumor cell lines and arise as promising chemotherapeutic candidates. However, conflicting results were reported regarding the actual effect of these drugs on cellular survival ranging from protection to toxicity. Moreover, the concentrations needed to observe such a toxicity were usually high, far above the affinity range for their receptor, hence questioning its specificity. In the present study, we have shown that micromolar concentrations of FGIN-1-27 and Ro 5-4864, two chemically unrelated PBR ligands are toxic for both PBR-expressing...
17.
Probing diffusion laws within cellular membranes by Z-scan fluorescence correlation spectroscopy - Humpolickova, J.; GIELEN, Ellen; Benda, A.; Fagulova, V.; VAN DE VEN, Martin; Hof, M.; AMELOOT, Marcel; Engelborghs, Y.
The plasma membrane of various mammalian cell types is heterogeneous in structure and may contain microdomains, which can impose constraints on the lateral diffusion of its constituents. Fluorescence correlation spectroscopy (FCS) can be used to investigate the dynamic properties of the plasma membrane of living cells. Very recently, Wawrezinieck et al. (Wawrezinieck, L., H. Rigneault, D. Marguet, and P. F. Lenne. 2005. Biophys. J. 89:4029-4042) described a method to probe the nature of the lateral microheterogeneities of the membrane by varying the beam size in the FCS instrument. The dependence of the width of the autocorrelation function at half-maximum, i.e.,...
18.
Mechanisms for picrotoxin block of alpha(2) homomeric glycine receptors - Wang, D.S.; MANGIN, Jean-Marie; Moonen, G; RIGO, Jean-Michel; Legendre, P
It is well known that the convulsant alkaloid picrotoxin (PTX) can inhibit neuronal gamma-aminobutyric acid ( GABA) and homomeric glycine receptors (GlyR). However, the mechanism for PTX block of alpha(2) homomeric GlyR is still unclear compared with that of alpha(1) homomeric GlyR, GABA(A), and GABA(C) receptors. Furthermore, PTX effects on GlyR kinetics have been poorly explored at the single-channel level. Hence, we used the patch-clamp technique in the outside-out configuration to investigate the mechanism of PTX suppression of currents carried by alpha(2) homomeric GlyRs stably transfected into Chinese hamster ovary cells. PTX inhibited the alpha(2) homomeric GlyR current elicited by...
19.
Frequency-dependent modulation of glycine receptor activation recorded from the zebrafish larvae hindbrain - RIGO, Jean-Michel; Legendre, P
In vertebrates, most glycinergic inhibitory neurons discharge phasically at a relatively low frequency. Such a pattern of glycine liberation from presynaptic terminals may affect the kinetics of post-synaptic glycine receptors. To examine this influence, we have analyzed the behavior of glycine receptors in response to repetitive stimulation at frequencies at which consecutive outside-out currents did not superimpose (0.5-4 Hz). Neurotransmitter release was mimicked on outside-out patches from zebrafish hindbrain Mauthner cells using fast flow application techniques. The amplitude of outside-out currents evoked by short (1 ms) repetitive applications of a saturating concentration (3 mM) of glycine remained unchanged for application...
20.
Rafts in oligodendrocytes: Evidence and structure-function relationship - GIELEN, Ellen; Baron, W; VAN DE VEN, Martin; STEELS, Paul; Hoekstra, D; AMELOOT, Marcel
The plasma membrane of eukaryotic cells exhibits lateral inhomogeneities, mainly containing cholesterol and sphingomyelin, which provide liquid-ordered microdomains (lipid "rafts") that segregate membrane components. Rafts are thought to modulate the biological functions of molecules that become associated with them, and as such, they appear to be involved in a variety of processes, including signal transduction, membrane sorting, cell adhesion and pathogen entry. Although still a matter of ongoing debate, evidence in favor of the presence of these microdomains is gradually accumulating but a consensus on issues like their size, lifetime, composition, and biological significance has yet to be reached. Here,...
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