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See detailFunctional glycine receptors are expressed by postnatal nestin-positive neural stem/progenitor cells
Nguyen, Laurent ULg; Malgrange, Brigitte ULg; Belachew, Shibeshih ULg et al

in European Journal of Neuroscience (2002), 15(8), 1299-1305

Multipotent neural stem and progenitor cells (NS/PCs) are well-established cell subpopulations occurring in the developing, and also in the mature mammalian nervous systems. Trophic and transcription ... [more ▼]

Multipotent neural stem and progenitor cells (NS/PCs) are well-established cell subpopulations occurring in the developing, and also in the mature mammalian nervous systems. Trophic and transcription factors are currently the main signals known to influence the development and the commitment of NS/PCs and their progeny. However, recent studies suggest that neurotransmitters could also contribute to neural development. In that respect, rodent-cultured embryonic NS/PCs have been reported to express functional neurotransmitter receptors. No similar investigation has, however, been made in postnatal and/or in adult rodent brain stem cells. In this study, using RT-PCR and immunocytochemical methods, we show that alpha(1) -, alpha(2) - and beta-subunit mRNAs and alpha-subunit proteins of the glycine ionotropic receptor are expressed by 80.5 +/- 0.9% of postnatal rat striatum-derived, nestin-positive cells within cultured neurospheres. Whole-cell patch-clamp experiments further demonstrated that glycine triggers in 33.5% of these cells currents that can be reversibly blocked by strychnine and picrotoxin. This demonstrates that NS/PCs express functional glycine receptors, the consequence(s) of their activation remaining unknown. [less ▲]

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See detailFunctional heterogeneity of human CD34(+) cells isolated in subcompartments of the G0 /G1 phase of the cell cycle.
GOTHOT, André ULg; Pyatt, R.; McMahel, J. et al

in Blood (1997), 90(11), 4384-93

Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34(+) cells were isolated in subcompartments of the G0 /G1 phase of the ... [more ▼]

Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34(+) cells were isolated in subcompartments of the G0 /G1 phase of the cell cycle by flow cytometric cell sorting. In both bone marrow (BM) and mobilized peripheral blood (MPB) CD34(+) cells, primitive long-term hematopoietic culture-initiating cell (LTHC-IC) activity was higher in CD34(+) cells isolated in G0 (G0CD34(+) cells) than in those residing in G1 (G1CD34(+) cells). However, as MPB CD34(+) cells displayed a more homogeneous cell-cycle status within the G0 /G1 phase and a relative absence of cells in late G1 , DNA/RNA fractionation was less effective in segregating LTHC-IC in MPB than in BM. BM CD34(+) cells belonging to four subcompartments of increasing RNA content within the G0 /G1 phase were evaluated in functional assays. The persistence of CD34 expression in suspension culture was inversely correlated with the initial RNA content of test cells. Multipotential progenitors were present in G0 or early G1 subcompartments, while lineage-restricted granulomonocytic progenitors were more abundant in late G1 . In vitro hematopoiesis was maintained for up to 6 weeks with G0CD34(+) cells, whereas production of clonogenic progenitors was more limited in cultures initiated with G1CD34(+) cells. To test the hypothesis that primitive LTHC-ICs would reenter a state of relative quiescence after in vitro division, BM CD34(+) cells proliferating in ex vivo cultures were identified from their quiescent counterparts by a relative loss of membrane intercalating dye PKH2, and were further fractionated with Hst and PY. The same functional hierarchy was documented within the PKH2(dim) population whereby LTHC-IC frequency was higher for CD34(+) cells reselected in G0 after in vitro division than for CD34(+) cells reisolated in G1 or in S/G2 + M. However, the highest LTHC-IC frequency was found in quiescent PKH2(bright) CD34(+) cells. Together, these results support the concept that cells with distinct hematopoietic capabilities follow different pathways during the G0 /G1 phase of the cell cycle both in vivo and during ex vivo culture. [less ▲]

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See detailFunctional identification of epithelial and smooth muscle histamine-dependent relaxing mechanisms in the bovine trachea, but not in bronchi
Jolly, Sandra ULg; Desmecht, Daniel ULg

in Comparative Biochemistry & Physiology Part C : Toxicology & Pharmacology (2003), 134(1), 91-100

Theoretically, the overall effect of histamine on respiratory smooth muscle is the result of a subtle balance of contraction and relaxation. The aim of the study was to identify histamine type 2 (H2) and ... [more ▼]

Theoretically, the overall effect of histamine on respiratory smooth muscle is the result of a subtle balance of contraction and relaxation. The aim of the study was to identify histamine type 2 (H2) and 3 (H3) receptor-dependent relaxing mechanisms in the contractile elements of the bovine tracheobronchial tree. In bronchial preparations, histamine induced very weak contractions, which were not exacerbated with the H2-antagonist cimetidine. Moreover, precontracted bronchial rings never relaxed in response to cumulative doses of histamine or amthamine (H2-agonist). In intact tracheal preparations, histamine induced strong contractions that were exacerbated by cimetidine (E-max : + 17.2 +/- 6.6%) but not by thioperamide (H3-antagonist). Precontracted tracheal bundles did not relax in response to cumulative doses of the H3-agonist R-alpha-methylhistamine. The tracheal contractile response was higher in denuded compared to intact preparations (11.0+/-1.2 vs. 6.0+/-1.7 g). Cimetidine effect was dramatically potentiated in denuded tracheal strips (+40.0+/-11.7%). It is concluded that the weak response. of bovine bronchi to histamine is due to a relative scarcity of H1 receptors on bronchial smooth muscle rather than to H2- or H3-dependent relaxation. In the bovine trachea, the smooth muscle possesses relaxing H2 but no H3 receptors. The epithelium exercises a relaxation, which is independent from H2 and H3 receptors. (C) 2002 Elsevier Science Inc. All rights reserved. [less ▲]

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See detailFunctional imaging and impaired consciousness
Vanhaudenhuyse, Audrey ULg; Boly, Mélanie ULg; Bruno, Marie-Aurélie ULg et al

in Schnakers, Caroline; Laureys, Steven (Eds.) Coma and disorders of consciousness (2012)

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See detailFunctional imaging of abdominal aortic aneurysms
Sakalihasan, Natzi ULg; Hustinx, Roland ULg; Gomez, Pierre et al

in Aortic Aneurysms, new insights of an old problem (2008)

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See detailFunctional imaging of abdominal aortic aneurysms : can it predict probability of rupture.
Sakalihasan, Natzi ULg; Hustinx, Roland ULg; Gomez, Pierre et al

in VASCULAR ANEURYSMS (2009)

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See detailFunctional imaging of atherosclerosis to advance vascular biology. Invited overview.
Sakalihasan, Natzi ULg; Michel, Jean-Baptiste

in European Journal of Vascular and Endovascular Surgery (2009), 37

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See detailFunctional imaging of cognition in Alzheimer's disease using positron emission tomography
Salmon, Eric ULg; Lekeu, Françoise ULg; Garraux, Gaëtan ULg et al

in Neuropsychologia (2008), 46(6), 1613-1623

Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving ... [more ▼]

Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving medial temporal structures and frontal regions at a lesser degree. The level of activity in this wide network is roughly correlated with dementia severity, but several confounds (such as age, education or subcortical ischemic lesions) may influence the brain-behaviour relationship. Univariate analyses allow one to segregate brain regions that are particularly closely related to specific neuropsychological performances. For example, a relationship was established between the activity in lateral associative cortices and semantic performance in AD. The role of semantic capacities (subserved by temporal or parietal regions) in episodic memory tasks was also emphasized. The residual activity in medial temporal structures was related to episodic memory abilities, as measured by free recall performance, cued recall ability and recognition accuracy. More generally, AD patients' performance on episodic memory tasks was correlated with the metabolism in several structures of Papez's circuit (including the medial temporal and posterior cingulate regions). Multivariate analyses should provide complementary information on impaired metabolic covariance in functional networks of brain regions and the consequences for AD patients' cognitive performance. More longitudinal studies are being conducted that should tell us more about the prognostic value of initial metabolic impairment and the neural correlates of progressive deterioration of cognitive performance in AD. [less ▲]

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See detailFunctional imaging of exercise-induced pulmonary haemorrhage
Votion, Dominique ULg

in Votion, Dominique; Serteyn, Didier; Lekeux, Pierre (Eds.) Exercise-Induced Pulmonary Haemorrhage: State of Current Knowledge (2008)

At present, the relative severity of the bleeding in exercise-induced pulmonary hemorrhage (EIPH) is better evaluated using scoring methods based on tracheobronchoscopic assessment of bleeding or red ... [more ▼]

At present, the relative severity of the bleeding in exercise-induced pulmonary hemorrhage (EIPH) is better evaluated using scoring methods based on tracheobronchoscopic assessment of bleeding or red blood cells (RBCs) count in broncho-alveolar lavage (BAL). However, misinterpretation might happen with tracheobronchoscopic examination when the hemorrhage is tiny as well as with RBCs count in BAL when the bronchi sampled are not representative of the bleeding site. Quantifying EIPH accurately would be of great interest to define the relationship between bleeding and performance as well as to assess efficacy of treatments or prophylactic measures. Several studies have attempted to determine whether lung imaging could be of value in EIPH detection and quantification. Radiographic findings when present consist of interstitial opacities limited to the caudodorsal regions of the lungs. Resolution of opacity may last for several days to several months. Interpretation of chest radiographs has found to be of poor value for diagnosing and a fortiori for quantifying EIPH and lung remodeling. Scintigraphy has been investigated as a mean of studying EIPH. Ventilation/perfusion (V/Q) scans show variable reduction of ventilation and a loss of perfusion in the caudodorsal fields but the relationship between V/Q mismatches and EIPH quantification seems hazardous. The exercise-induced pulmonary perfusion redistribution may be visualized and quantified with labeled radiotracers entrapped in the pulmonary capillaries following their intravenous injection in exercising horses. This technique may not detect EIPH because scanning does not distinguish tracer collected in alveoli (i.e. resulting from bleeding) versus trapped in the capillaries. The same is true with the use of labeled-RBCs: circulating tracer impedes visualization of bleeding. To visualize the bleeding site, radioactivity of the vascular blood pool should be removed. A preliminary study indicated that this background might be removed using a double isotope scintigraphy. In fact, horse would be first injected at exercise with RBCs labeled with 111-Indium (111In-RBCs). In bleeders, a scan taken at the end of exercise would include the hemorrhage hidden by the blood pool. As EIPH is presumed to resolve with exercise cessation due to immediate decrease in pulmonary artery pressure, a second injection of RBCs labeled with another radiotracer (99m-technetium; 99mTc-RBCs) would enable acquisition of the sole blood pool knowing that 99mTc and 111In activities may be recorded on two different channels. Then, the computerized removal of background vascular radioactivity should enable to visualize the bleeding site and possibly to quantify the amount of extravasated blood. [less ▲]

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See detailFunctional imaging of inflammatory airway disease
Votion, Dominique ULg

in Hoffman, A.; Robinson, N. E.; Wade, J. F. (Eds.) Inflammation Airway Disease: Defining the Syndrome (2002)

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See detailFunctional Magnetic Resonance Imaging-Assessed Brain Responses during an Executive Task Depend on Interaction of Sleep Homeostasis, Circadian Phase, and PER3 Genotype
Vandewalle, Gilles ULg; Archer, S.; Wuillaume, C. et al

in Journal of Neuroscience (2009), 29

Cognition is regulated across the 24 h sleep-wake cycle by circadian rhythmicity and sleep homeostasis through unknown brain mechanisms. We investigated these mechanisms in a functional magnetic resonance ... [more ▼]

Cognition is regulated across the 24 h sleep-wake cycle by circadian rhythmicity and sleep homeostasis through unknown brain mechanisms. We investigated these mechanisms in a functional magnetic resonance imaging study of executive function using a working memory 3-back task during a normal sleep-wake cycle and during sleep loss. The study population was stratified according to homozygosity for a variable-number (4 or 5) tandem-repeat polymorphism in the coding region of the clock gene PERIOD3. This polymorphism confers vulnerability to sleep loss and circadian misalignment through its effects on sleep homeostasis. In the less-vulnerable genotype, no changes were observed in brain responses during the normal-sleep wake cycle. During sleep loss, these individuals recruited supplemental anterior frontal, temporal and subcortical regions, while executive function was maintained. In contrast, in the vulnerable genotype, activation in a posterior prefrontal area was already reduced when comparing the evening to the morning during a normal sleep-wake cycle. Furthermore, in the morning after a night of sleep loss, widespread reductions in activation in prefrontal, temporal, parietal and occipital areas were observed in this genotype. These differences occurred in the absence of genotype-dependent differences in circadian phase. The data show that dynamic changes in brain responses to an executive task evolve across the sleep-wake and circadian cycles in a regionally specific manner that is determined by a polymorphism which affects sleep homeostasis. The findings support a model of individual differences in executive control, in which the allocation of prefrontal resources is constrained by sleep pressure and circadian phase. [less ▲]

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See detailFunctional Maturation of the Gabaergic Inhibition on Dopamine-Mediated Behaviours During the Neonatal Period in the Mouse
Tirelli, Ezio ULg

in Behavioural Brain Research (1989), 33(1), 83-95

Previous works have indicated that systemic injection of GABA-agonists depress motoric behaviours in neonatal murids, suggesting an early maturation of GABAergic inhibitory processes. In this paper, the ... [more ▼]

Previous works have indicated that systemic injection of GABA-agonists depress motoric behaviours in neonatal murids, suggesting an early maturation of GABAergic inhibitory processes. In this paper, the inhibitory effects of muscimol, a postsynaptic GABAA-agonist, on D-amphetamine-induced enhancement of locomotion, wall-climbing and head-raising were examined in neonatal 5-, 8- and 11-day-old mouse pups, using a direct observational procedure. The results show that muscimol can selectively attenuate high levels of locomotion, wall-climbing and head-raising produced by the indirect dopamine agonist in 8- as well as 11-day-old pups. However, while muscimol is able to moderate amphetamine-induced wall-climbing and head-rising in 5-day-old pups, no GABAergic inhibition was seen for locomotion at this age. Licking episodes elicited by amphetamine in 11-day-old pups can be magnified by muscimol if the dosage of the former is relatively too potent. It is suggested that the GABAergic inhibitory processes on dopaminergic functioning have reached good levels of functional maturation in the neonatal murid. [less ▲]

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See detailFunctional modes of proteins are among the most robust
Nicolay, Samuel ULg; Sanejouand, Y. H.

in Physical Review Letters (2004), 96

It is shown that a small subset of modes which are likely to be involved in protein functional motions of large amplitude can be determined by retaining the most robust normal modes obtained using ... [more ▼]

It is shown that a small subset of modes which are likely to be involved in protein functional motions of large amplitude can be determined by retaining the most robust normal modes obtained using different protein models. This result should prove helpful in the context of several applications proposed recently, like for solving difficult molecular replacement problems or for fitting atomic structures into low- resolution electron density maps. It may also pave the way for the development of methods allowing us to predict such motions accurately. [less ▲]

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See detailFunctional morphology of Tethya species (Porifera): 2. Three-dimensional morphometrics on spicules and skeleton superstructures of T-minuta
Nickel, M.; Bullinger, Eric ULg; Beckmann, F.

in Zoomorphology (2006), 125(4), 225-239

The biomechanics of body contraction in Porifera is almost unknown, although sponge contraction has been observed already in ancient times. Some members of the genus Tethya represent the most contractile ... [more ▼]

The biomechanics of body contraction in Porifera is almost unknown, although sponge contraction has been observed already in ancient times. Some members of the genus Tethya represent the most contractile poriferan species. All of them show a highly ordered skeleton layout. Based on three main spicule types, functional units are assembled, termed skeleton superstructures here. Using synchrotron radiation based x-ray microtomography and quantitative image analysis with specially developed particle and structure recognition algorithms allowed us to perform spatial allocation and 3D-morphometric characterizations of single spicules and skeleton superstructures in T. minuta. We found and analyzed three skeleton superstructures in the investigated specimen: (1) 85 megasclere bundles, (2) a megaster sphere, composed by 16,646 oxyasters and (3) a pinacoderm-tylaster layer composed by micrasters. All three skeleton superstructures represent composite materials of siliceous spicules and extracellular matrix. From structure recognition we developed an abstracted mathematical model of the bundles and the sphere. In addition, we analyzed the megaster network interrelation topology and found a baso-apical linear symmetry axis for the megaster density inside the sphere. Based on our results, we propose a hypothetical biomechanical contraction model for T. minuta and T. wilhelma, in which the skeleton superstructures restrain physical stress generated by contraction in the tissue. While skeletal structures within the genus Tethya have been explained using R. Buckminster Fullers principle of tensegrity by other authors, we prefer material science based biomechanical approaches, to understand skeletal superstructures by referring to their composite material properties. [less ▲]

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See detailFunctional morphology of the sonic apparatus in Ophidion barbatum (Teleostei, Ophidiidae)
Parmentier, Eric ULg; Fontenelle, N.; Fine, M. L. et al

in Journal of Morphology (2006), 267(12), 1461-1468

Most soniferous fishes producing sounds with their swimbladder utilize relatively simple mechanisms: contraction and relaxation of a unique pair of sonic muscles cause rapid movements of the swimbladder ... [more ▼]

Most soniferous fishes producing sounds with their swimbladder utilize relatively simple mechanisms: contraction and relaxation of a unique pair of sonic muscles cause rapid movements of the swimbladder resulting in sound production. Here we describe the sonic mechanism for Ophidion barbatum, which includes three pairs of sonic muscles, highly transformed vertebral centra and ribs, a neural arch that pivots and a swimbladder whose anterior end is modified into a bony structure, the rocker bone. The ventral and intermediate muscles cause the rocker bone to swivel inward, compressing the swimbladder, and this action is antagonized by the dorsal muscle. Unlike other sonic systems in which the muscle contraction rate determines sound fundamental frequency, we hypothesize that slow contraction of these antagonistic muscles produces a series of cycles of swimbladder vibration. [less ▲]

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See detailFunctional morphology of the sonic apparatus in the fawn cusk-eel Lepophidium profundorum (Gill, 1863)
Fine, M. L.; Lin, H.; Nguyen, B. B. et al

in Journal of Morphology (2007), 268(11), 953-966

Recent reports of high frequency sound production by cusk-eels cannot be explained adequately by known mechanisms, i.e., a forced response driven by fast sonic muscles on the swimbladder. Time to complete ... [more ▼]

Recent reports of high frequency sound production by cusk-eels cannot be explained adequately by known mechanisms, i.e., a forced response driven by fast sonic muscles on the swimbladder. Time to complete a contraction-relaxation cycle places a ceiling on frequency and is unlikely to explain sounds with dominant frequencies above 1 kHz. We investigated sonic morphology in the fawn cusk-eel Lepophidium profundorum to determine morphology potentially associated with high frequency sound production and quantified development and sexual dimorphism of sonic structures. Unlike other sonic systems in fishes in which muscle relaxation is caused by internal pressure or swimbladder elasticity, this system utilizes antagonistic pairs of muscles: ventral and intermediate muscles pull the winglike process and swimbladder forward and pivot the neural arch (neural rocker) above the first vertebra backward. This action stretches a fenestra in the swimbladder wall and imparts strain energy to epineural ribs, tendons and ligaments connected to the anterior swimbladder. Relatively short antagonistic dorsal and dorsomedial muscles pull on the neural rocker, releasing strain energy, and use a lever advantage to restore the winglike process and swimbladder to their resting position. Sonic components grow isometrically and are typically larger in males although the tiny intermediate muscles are larger in females. Although external morphology is relatively conservative in ophidiids, sonic morphology is extremely variable within the family. [less ▲]

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