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See detailImpaired motor coordination and Purkinje cell excitability in mice lacking calretinin
Schiffmann, Serge N.; Cheron, Guy; Lohoff, Ann et al

in Proceedings of the National Academy of Sciences of the United States of America (1999), 96

n the cerebellum, the parallel fiber-Purkinje cell synapse can undergo long-term synaptic plasticity suggested to underlie motor learning and resulting from variations in intracellular calcium ... [more ▼]

n the cerebellum, the parallel fiber-Purkinje cell synapse can undergo long-term synaptic plasticity suggested to underlie motor learning and resulting from variations in intracellular calcium concentration ([Ca2+]i). Ca2+ binding proteins are enriched in the cerebellum, but their role in information processing is not clear. Here, we show that mice deficient in calretinin (Cr-/-) are impaired in tests of motor coordination. An impairment in Ca2+ homeostasis in Cr-/- Purkinje cells was supported by the high Ca2+-saturation of calbindin-D28k in these cells. The firing behavior of Purkinje cells is severely affected in Cr-/- alert mice, with alterations of simple spike firing rate, complex spike duration, and simple spike pause. In contrast, in slices, transmission at parallel fiber- or climbing fiber-Purkinje cell synapses is unaltered, indicating that marked modifications of the firing behavior in vivo can be undetectable in slice. Thus, these results show that calretinin plays a major role at the network level in cerebellar physiology [less ▲]

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See detailImpaired neuromuscular transmission and skeletal muscle fiber necrosis in mice lacking Na/Ca exchanger 3
Sokolow, S.; Manto, M.; Gailly, P. et al

in Journal of Clinical Investigation (2004), 113

We produced and analyzed mice deficient for Na/Ca exchanger 3 (NCX3), a protein that mediates cellular Ca(2+) efflux (forward mode) or Ca(2+) influx (reverse mode) and thus controls intracellular Ca(2 ... [more ▼]

We produced and analyzed mice deficient for Na/Ca exchanger 3 (NCX3), a protein that mediates cellular Ca(2+) efflux (forward mode) or Ca(2+) influx (reverse mode) and thus controls intracellular Ca(2+) concentration. NCX3-deficient mice (Ncx3(-/-)) present a skeletal muscle fiber necrosis and a defective neuromuscular transmission, reflecting the absence of NCX3 in the sarcolemma of the muscle fibers and at the neuromuscular junction. The defective neuromuscular transmission is characterized by the presence of electromyographic abnormalities, including low compound muscle action potential amplitude, a decremental response at low-frequency nerve stimulation, an incremental response, and a prominent postexercise facilitation at high-frequency nerve stimulation, as well as neuromuscular blocks. The analysis of quantal transmitter release in Ncx3(-/-) neuromuscular junctions revealed an important facilitation superimposed on the depression of synaptic responses and an elevated delayed release during high-frequency nerve stimulation. It is suggested that Ca(2+) entering nerve terminals is cleared relatively slowly in the absence of NCX3, thereby enhancing residual Ca(2+) and evoked and delayed quantal transmitter release during repetitive nerve stimulation. Our findings indicate that NCX3 plays an important role in vivo in the control of Ca(2+) concentrations in the skeletal muscle fibers and at the neuromuscular junction [less ▲]

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See detailImpaired respiration discloses the physiological significance of state transitions in Chlamydomonas.
Cardol, Pierre ULg; Alric, Jean; Girard-Bascou, Jacqueline et al

in Proceedings of the National Academy of Sciences of the United States of America (2009), 106(37), 15979-84

State transitions correspond to a major regulation process for photosynthesis, whereby chlorophyll protein complexes responsible for light harvesting migrate between photosystem II and photosystem I in ... [more ▼]

State transitions correspond to a major regulation process for photosynthesis, whereby chlorophyll protein complexes responsible for light harvesting migrate between photosystem II and photosystem I in response to changes in the redox poise of the intersystem electron carriers. Here we disclose their physiological significance in Chlamydomonas reinhardtii using a genetic approach. Using single and double mutants defective for state transitions and/or mitochondrial respiration, we show that photosynthetic growth, and therefore biomass production, critically depends on state transitions in respiratory-defective conditions. When extra ATP cannot be provided by respiration, enhanced photosystem I turnover elicited by transition to state 2 is required for photosynthetic activity. Concomitant impairment of state transitions and respiration decreases the overall yield of photosynthesis, ultimately leading to reduced fitness. We thus provide experimental evidence that the combined energetic contributions of state transitions and respiration are required for efficient carbon assimilation in this alga. [less ▲]

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See detailImpaired semantic knowledge underlies the reduced verbal short-term storage capacity in Alzheimer's disease.
Peters, Frederic; Majerus, Steve ULg; De Baerdemaeker, Julie et al

in Neuropsychologia (2009), 47(14), 3067-73

A decrease in verbal short-term memory (STM) capacity is consistently observed in patients with Alzheimer's disease (AD). Although this impairment has been mainly attributed to attentional deficits during ... [more ▼]

A decrease in verbal short-term memory (STM) capacity is consistently observed in patients with Alzheimer's disease (AD). Although this impairment has been mainly attributed to attentional deficits during encoding and maintenance, the progressive deterioration of semantic knowledge in early stages of AD may also be an important determinant of poor STM performance. The aim of this study was to examine the influence of semantic knowledge on verbal short-term memory storage capacity in normal aging and in AD by exploring the impact of word imageability on STM performance. Sixteen patients suffering from mild AD, 16 healthy elderly subjects and 16 young subjects performed an immediate serial recall task using word lists containing high or low imageability words. All participant groups recalled more high imageability words than low imageability words, but the effect of word imageability on verbal STM was greater in AD patients than in both the young and the elderly control groups. More precisely, AD patients showed a marked decrease in STM performance when presented with lists of low imageability words, whereas recall of high imageability words was relatively well preserved. Furthermore, AD patients displayed an abnormal proportion of phonological errors in the low imageability condition. Overall, these results indicate that the support of semantic knowledge on STM performance was impaired for lists of low imageability words in AD patients. More generally, these findings suggest that the deterioration of semantic knowledge is partly responsible for the poor verbal short-term storage capacity observed in AD. [less ▲]

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See detailImpaired short-term memory for order in adults with dyslexia
Martinez Perez, Trecy ULg; Majerus, Steve ULg; Poncelet, Martine ULg

in Research in Developmental Disabilities (2013), 34

Verbal short-term memory (STM) deficits are consistently associated with dyslexia, but the nature of these deficits remains poorly understood. This study used the distinction between item and order ... [more ▼]

Verbal short-term memory (STM) deficits are consistently associated with dyslexia, but the nature of these deficits remains poorly understood. This study used the distinction between item and order retention processes to achieve a better understanding of STM deficits in adults with dyslexia. STM for item information has been shown to depend on the quality of underlying phonological representations, and hence should be impaired in dyslexia, which is characterized by poorly developed phonological representations. On the other hand, STM for order information is considered to reflect core STM processes, which are independent from language processing. Thirty adults with dyslexia and thirty control participants matched for age, education, vocabulary, and IQ were presented STM tasks, which distinguished item and order STM capacities. We observed not only impaired order STM in adults with dyslexia, but this impairment was independent of item STM impairment. This study shows that adults with dyslexia present a deficit in core verbal STM processes, a deficit which cannot be accounted for by the language processing difficulties that characterize dyslexia. Moreover, these results support recent theoretical accounts considering independent order STM and item STM processes, with a potentially causal involvement of order STM processes in reading acquisition. [less ▲]

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See detailImpaired verbal short-term memory for serial order information in dyslexic adults
Martinez Perez, Trecy ULg; Majerus, Steve ULg; Poncelet, Martine ULg

Poster (2010, September 10)

This study used the distinction of item and order information in verbal short-term memory (STM) to further our understanding of verbal STM impairments in dyslexia. Item STM has been shown to depend on the ... [more ▼]

This study used the distinction of item and order information in verbal short-term memory (STM) to further our understanding of verbal STM impairments in dyslexia. Item STM has been shown to depend on the quality of underlying phonological representations and hence should be impaired in dyslexic participants given their poor phonological processing abilities. On the other hand, order STM represents a specific STM capacity predicting learning capacity for new phonological and orthographic sequences (Majerus et al., 2006; Nithart et al, 2010). If STM impairments contribute to dyslexia, then especially order STM should be impaired, in addition to item STM. [less ▲]

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See detailImpairment of mitochondrial functions abolishes NF-kappaB activation by an oxidative stress
Josse, Claire ULg; Legrand-Poels, Sylvie ULg; Piret, Bernard et al

in Free Radical Biology & Medicine (1998)

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See detailImpairment of neocortical metabolism predicts progression in Alzheimer's disease
Herholz, K.; Nordberg, A.; Salmon, Eric ULg et al

in Dementia & Geriatric Cognitive Disorders (1999), 10(6), 494-504

Studied prediction of progression rates of Alzheimer's disease (AD) in a prospective multicenter cohort study of 186 patients (mean age 63.2 yrs) with possible or probable AD, mostly with presenile onset ... [more ▼]

Studied prediction of progression rates of Alzheimer's disease (AD) in a prospective multicenter cohort study of 186 patients (mean age 63.2 yrs) with possible or probable AD, mostly with presenile onset. In a cross-sectional analysis at entry, impairment of glucose metabolism in temporoparietal or frontal association areas measured with positron emission tomography was significantly associated with dementia severity, clinical classification as possible vs probable AD, presence of multiple cognitive deficits and history of progression. A prospective longitudinal analysis showed a significant association between initial metabolic impairment and subsequent clinical deterioration. In patients with mild cognitive deficits at entry, the risk of deterioration was up to 4.7 times higher if the metabolism was severely impaired than with mild or absent metabolic impairment. [less ▲]

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See detailImpairment of neuromuscular transmission in a subgroup of migraine patients
Ambrosini, Anna; MAERTENS DE NOORDHOUT, Alain ULg; Alagona, Giovanna et al

in Neuroscience Letters (1999), 276(3), 201-3

Neuronal voltage-dependent P/Q Ca2+ channels are genetically abnormal in many cases of familial hemiplegic migraine and possibly associated with the more common forms of migraine with and without aura ... [more ▼]

Neuronal voltage-dependent P/Q Ca2+ channels are genetically abnormal in many cases of familial hemiplegic migraine and possibly associated with the more common forms of migraine with and without aura. Besides the brain, these channels are found in motor nerve endings where they control stimulation-induced acetylcholine release. Using single fiber EMG recordings we were able to demonstrate subclinical abnormalities of neuromuscular transmission in a subgroup of patients suffering from migraine with aura. This could be related to genetic abnormalities of P/Q Ca2+ channels in certain patients suffering from migraine with aura, which needs to be explored by proper genetic analyses. [less ▲]

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See detailImpairment of renal function with increasing blood lead concentrations in the general population
Staessen, Jan; Lauwerys, Robert; Buchet, Jean-Pierre et al

in New England Journal of Medicine [=NEJM] (1992), 327(3), 151-156

Cadmium and lead are toxic to the kidney. Both metals are known to induce nephropathy in subjects with heavy exposure. Environmental exposure to cadmium is associated with renal tubular dysfunction, but ... [more ▼]

Cadmium and lead are toxic to the kidney. Both metals are known to induce nephropathy in subjects with heavy exposure. Environmental exposure to cadmium is associated with renal tubular dysfunction, but few studies have attempted to evaluate the renal effects of environmental lead exposure. A weak positive correlation between serum creatinine and blood lead concentrations was found in men, but not women, in the British civil service. We investigated the relation between lead exposure and renal function in the general population, using data obtained during the Cadmibel (Cadmium in Belgium) Study. Lead exposure was estimated by measuring blood concentrations of lead and zinc protoporphyrin, which is increased in the presence of high lead levels. [less ▲]

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See detailImpairment of symbiont photosynthesis increases host cell proliferation in the epidermis of the sea anemone Aiptasia pallida
Fransolet, David ULg; Roberty, Stéphane ULg; Plumier, Jean-Christophe ULg

in Marine Biology (2014)

Corals exposed to environmental stresses need to engage appropriate physiological strategies to survive. Here we examined tissue modifications following algal dysfunction. Aiptasia pallida was exposed ... [more ▼]

Corals exposed to environmental stresses need to engage appropriate physiological strategies to survive. Here we examined tissue modifications following algal dysfunction. Aiptasia pallida was exposed during one week to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), the herbicide called Diuron. DCMU treatment produced a drastic loss in photosynthetic efficiency and a subsequent diminution of algae density over the following days. Cell proliferation evaluated by measuring the number of cells labeled with a thymidine analogue (EdU) revealed a significant increase in EdU+ cells in the epidermis after one week of DCMU incubation and in the gastrodermis at four weeks. TUNEL histology showed that the extent of cell death was however similar in the epidermis of control and treated specimens. In addition we noticed a significant effect of DCMU treatment on the density of epidermal mucocytes after one, two and four weeks. These results show that inhibition of Symbiodinium photosynthesis in the absence of any known direct effect of DCMU on host cells can induce an increase of epidermal host cell proliferation in both the epidermis and the gastrodermis. While new host gastrodermal cells are likely to promote tissue regeneration in order to recruit new algae, the new host epidermal cells may contribute to tissue adaptation following a decrease in energy income. Some of these new epidermal cells, such as mucocytes, may contribute to an eventual increase of the host heterotrophic ability until restoration of algal autotrophic contribution. [less ▲]

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See detailImpairment of the M-protein and unmasking of a superficial type-specific antigen by proteolytic treatment of influenza A virions with preservation of host-specific antigenicity
Reginster, Monique; Rentier, Bernard ULg; Dierickx, Louis

in Intervirology (1976), 6(4-5), 239-248

Influenza PR8 particles resulting from strong treatment with caseinase C are spikeless, devoid of neuraminidase and hemagglutinin 1 and 2 glycopeptides, and contain a Schiff-neg. polypeptide of about 13 ... [more ▼]

Influenza PR8 particles resulting from strong treatment with caseinase C are spikeless, devoid of neuraminidase and hemagglutinin 1 and 2 glycopeptides, and contain a Schiff-neg. polypeptide of about 13,000 mol. wt. which exists as traces in intact virions. Their M-protein polypeptide content is reduced to 50% of its original value, but there is no evidence of particle disruption nor of lipid release. They fix complement in the presence of both anti-M-protein and antiserum raised against a host polysaccharide. During exposure to caseinase C, an antigen is unmasked. It is type-specific and its identity with the M-protein is discussed [less ▲]

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See detailImpairment of the mitochondrial electron chain transport prevents NF-kappa B activation by hydrogen peroxide.
Josse, C.; Legrand-Poels, S.; Piret, B. et al

in Free Radical Biology & Medicine (1998), 25(1), 104-112

A large body of work has been devoted to mechanisms leading to the activation of the transcription factor NF-kappa B in various cell types. Several studies have indicated that NF-kappa B activation by ... [more ▼]

A large body of work has been devoted to mechanisms leading to the activation of the transcription factor NF-kappa B in various cell types. Several studies have indicated that NF-kappa B activation by numerous stimuli depends on the intracellular generation of reactive oxygen species (ROS). In this report, we first demonstrated that inhibition of the electron transport chain by either rotenone or antimycine A gave rise to dose-dependent inhibition of NF-kappa B translocation induced by 150 microM of hydrogen peroxide (H2O2). Conversely, the impairment of the mitochondrial respiratory chain did not affect T lymphocyte treatment by TNF-alpha (tumor necrosis factor alpha) or pre-B lymphocyte treatment with LPS (lipopolysaccharide). We also showed that oligomycine which inhibits ATP synthase and FCCP, which uncouples respiration also led to dose-dependent inhibition of NF-kappa B activation by H2O2. All these inhibitors were also shown to inhibit mitochondrial respiration in lymphocytes assessed by oxygen consumption. Although only a transient drop in ATP concentration was observed when lymphocytes were treated by H2O2, this effect was remarkably reinforced in the presence of oligomycine demonstrating the crucial role of ATP in the signal transduction pathway induced by H2O2. [less ▲]

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See detailImpairment of two memory cerebral networks in Alzheimer's disease
Bastin, Christine ULg; Bahri, Mohamed Ali ULg; Collette, Fabienne ULg et al

in Proceedings of the Annual Meeting of the Belgian Association for Psychological Sciences (2013)

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See detailImpairments of 3D visual perception in posterior cortical atrophy: functional and anatomical characterization
Gillebert, Céline; Bastin, Christine ULg; Sunaert, Stefan et al

Conference (2013)

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See detailImpala: A Simple Restraint Field To Simulate The Biological Membrane In Molecular Structure Studies
Ducarme, P.; Rahman, M.; Brasseur, Robert ULg

in Proteins-Structure Function and Bioinformatics (1998), 30(4), 357-71

The lipid bilayer is crucial for the folding of integral membrane proteins. This article presents an empirical method to account for water-lipid interfaces in the insertion of molecules interacting with ... [more ▼]

The lipid bilayer is crucial for the folding of integral membrane proteins. This article presents an empirical method to account for water-lipid interfaces in the insertion of molecules interacting with bilayers. The interactions between the molecule and the bilayer are described by restraint functions designed to mimic the membrane effect. These functions are calculated for each atom and are proportional to the accessible surface of the latter. The membrane is described as a continuous medium whose properties are varying along the axis perpendicular to the bilayer plane. The insertion is analyzed by a Monte Carlo procedure applied to the restraint functions. The method was successfully applied to small alpha peptides of known configurations. It provides insights of the behaviors of the peptide dynamics that cannot be obtained with statistical approaches (e.g., hydropathy analysis). [less ▲]

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See detailImparting antifouling properties of poly(2-hydroxyethyl methacrylate) hydrogels by grafting poly(oligoethylene glycol methyl ether acrylate)
Bozukova, Dimitriya ULg; Pagnoulle, Christophe; Gillet, Marie-Claire ULg et al

in Langmuir (2008), 24(13), 6649-6658

The antifouling properties of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogels were improved by the surface grafting of a brush of poly(oligoethylene glycol methyl ether acrylate) [poly ... [more ▼]

The antifouling properties of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogels were improved by the surface grafting of a brush of poly(oligoethylene glycol methyl ether acrylate) [poly(OEGA)]. The atom-transfer radical polymerization (ATRP) of OEGA (degree of polymerization = 8) was initiated from the preactivated surface of the hydrogel under mild conditions, thus in water at 25 °C. The catalytic system was optimized on the basis of two ligands [1,1,4,7,10,10-hexamethyl-triethylenetetramine (HMTETA) or tris[2-(dimethylamino)ethyl]amine (Me6TREN)] and two copper salts (CuIBr or CuICl). Faster polymerization was observed for the Me6TREN/CuIBr combination. The chemical composition and morphology of the coated surface were analyzed by X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements by the water droplet and captive bubble methods, scanning electron microscopy, and environmental scanning electron microscopy. The hydrophilicity of the surface increased with the molar mass of the grafted poly(OEGA) chains, and the surface modifications were reported in parallel. The antifouling properties of the coatings were tested by in vitro protein adsorption and cell adhesion tests, with green fluorescent protein, β-lactamase, and lens epithelial cells, as model proteins and model cells, respectively. The grafted poly(OEGA) brush decreased the nonspecific protein adsorption and imparted high cell repellency to the hydrogel surface. [less ▲]

Detailed reference viewed: 71 (13 ULg)