Biomedical subjects

Y Bailly

Publications and source records attributed to Y Bailly.

At least 19 recordsLinked to original sources

PubMed2003

Alzheimer's disease proteins in cerebellar and hippocampal synapses during postnatal development and aging of the rat.

Alzheimer's dementia may be considered a synaptic disease of central neurons: the loss of synapses, reflected by early cognitive impairments, precedes the appearance of extra cellular focal deposits of beta-amyloid peptide in the brain of patients. Distinct immunocytochemical patterns of amyloid precursor proteins (APPs) have previously been demonstrated in the synapses by ultrastructural analysis in the cerebellum and hippocampus of adult rats and mice. Now we show that during postnatal development and during aging in these structures, the immunocytochemical expression of APPs increases in the synapses in parallel with the known up-regulation of total APPs brain levels. Interestingly, as shown previously in the adult rodents, the presenilins (PSs) 1 and 2, which intervene in APPs metabolism, exhibit a synaptic distribution pattern similar to that of APPs with parallel quantitative changes throughout life. In the brain tissue, single and double immunocytochemistry at the ultrastructural level shows co-localisation of APPs and PSs in axonal and dendritic synaptic compartments during postnatal synaptogenesis, adulthood and aging. In addition, double-labelling immunocytofluorescence detects these proteins close to synaptophysin at the growth cones of developing cultured neurons. Thusly, the brain expression of APPs and PSs appears to be regulated synchronously during lifespan in the synaptic compartments where the proteins are colocated. This suggests that PS-dependent processing of important synaptic proteins such as APPs could intervene in age-induced adjustments of synaptic relationships between specific types of neurons.

Aging↗

PubMed2001

Molecular cloning and characterization of phocein, a protein found from the Golgi complex to dendritic spines.

Phocein is a widely expressed, highly conserved intracellular protein of 225 amino acids, the sequence of which has limited homology to the sigma subunits from clathrin adaptor complexes and contains an additional stretch bearing a putative SH3-binding domain. This sequence is evolutionarily very conserved (80% identity between Drosophila melanogaster and human). Phocein was discovered by a yeast two-hybrid screen using striatin as a bait. Striatin, SG2NA, and zinedin, the three mammalian members of the striatin family, are multimodular, WD-repeat, and calmodulin-binding proteins. The interaction of phocein with striatin, SG2NA, and zinedin was validated in vitro by coimmunoprecipitation and pull-down experiments. Fractionation of brain and HeLa cells showed that phocein is associated with membranes, as well as present in the cytosol where it behaves as a protein complex. The molecular interaction between SG2NA and phocein was confirmed by their in vivo colocalization, as observed in HeLa cells where antibodies directed against either phocein or SG2NA immunostained the Golgi complex. A 2-min brefeldin A treatment of HeLa cells induced the redistribution of both proteins. Immunocytochemical studies of adult rat brain sections showed that phocein reactivity, present in many types of neurons, is strictly somato-dendritic and extends down to spines, just as do striatin and SG2NA.

Amino Acid Sequence↗

PubMed2000

Synaptic prion protein immuno-reactivity in the rodent cerebellum.

The cellular prion protein PrP(c) is a neurolemmal glycoprotein essential for the development of the transmissible spongiform encephalopathies. In these neurodegenerative diseases, host PrP(c) is converted to infectious protease-resistant isoforms PrP(res) or prions. Prions provoque predictable and distinctive patterns of PrP(res) accumulation and neurodegeneration depending on the prion strain and on regional cell-specific properties modulating PrP(c) affinity for infectious PrP(res) in the host brain. Synaptolysis and synaptic accumulation of PrP(res) during PrP-related diseases suggests that the synapses could be primary sites able to propagate PrP(res) and neurodegeneration in the central nervous system. In the rodent cerebellum, the present light and electron microscopic immuno-cytochemical analysis shows that distinct types of synapses display differential expression of PrP(c), suggesting that synapse-specific parameters could influence neuroinvasion and neurodegeneration following cerebral infection by prions. Although the physiological functions of PrP(c) remain unknown, the concentration of PrP(c) almost exclusively at the Purkinje cell synapses in the cerebellum suggests its critical involvement in the synaptic relationships between cerebellar neurons in agreement with their known vulnerability to PrP deficiencies.

Animals↗

PubMed2000

Olivocerebellar climbing fibers in the granuloprival cerebellum: morphological study of individual axonal projections in the X-irradiated rat.

Elimination of cerebellar granule cells early during postnatal development produces abnormal neural organization that retains immature characteristics in the adult, including innervation of each Purkinje cell by multiple climbing fibers from the inferior olive. To elucidate mechanisms underlying development of the olivocerebellar projection, we studied light-microscopic morphology of single olivocerebellar axons labeled with biotinylated dextran amine in adult rats rendered agranular by a single postnatal X-irradiation. Each reconstructed olivocerebellar axon gave off approximately 12 climbing fibers, approximately twice as many as in normal rats. Terminal arborizations of climbing fibers made irregular tufts in most areas, whereas they were arranged vertically in a few mildly affected areas. Each climbing fiber terminal arborization innervated only part of the dendritic arbor of a Purkinje cell, and multiple climbing fibers innervated a single Purkinje cell. These climbing fibers originated either from the same olivocerebellar axon (pseudomultiple innervation) or from distinct axons (true multiple innervation). Abundant non-climbing fiber thin collaterals projected to all cortical layers. Although the longitudinal pattern of the zonal olivocerebellar projection was generally observed, lateral branching, including bilateral projections, was relatively frequent. These results suggest that the granule cell-parallel fiber system induces several important features of olivocerebellar projection: (1) organization of the climbing fiber terminal arborization tightly surrounding Purkinje cell dendrites, (2) elimination of pseudo- and true multiple innervations establishing one-to-one innervation, (3) retraction of non-climbing fiber thin collaterals from the molecular layer, and (4) probable refinement of the longitudinal projection domains by removing aberrant transverse branches.

Age Factors↗

PubMed2000

Epithelial and endothelial expression of the green fluorescent protein reporter gene under the control of bovine prion protein (PrP) gene regulatory sequences in transgenic mice.

The expression of the cellular form of the prion protein (PrP(c)) gene is required for prion replication and neuroinvasion in transmissible spongiform encephalopathies. The identification of the cell types expressing PrP(c) is necessary to understanding how the agent replicates and spreads from peripheral sites to the central nervous system. To determine the nature of the cell types expressing PrP(c), a green fluorescent protein reporter gene was expressed in transgenic mice under the control of 6.9 kb of the bovine PrP gene regulatory sequences. It was shown that the bovine PrP gene is expressed as two populations of mRNA differing by alternative splicing of one 115-bp 5' untranslated exon in 17 different bovine tissues. The analysis of transgenic mice showed reporter gene expression in some cells that have been identified as expressing PrP, such as cerebellar Purkinje cells, lymphocytes, and keratinocytes. In addition, expression of green fluorescent protein was observed in the plexus of the enteric nervous system and in a restricted subset of cells not yet clearly identified as expressing PrP: the epithelial cells of the thymic medullary and the endothelial cells of both the mucosal capillaries of the intestine and the renal capillaries. These data provide valuable information on the distribution of PrP(c) at the cellular level and argue for roles of the epithelial and endothelial cells in the spread of infection from the periphery to the brain. Moreover, the transgenic mice described in this paper provide a model that will allow for the study of the transcriptional activity of the PrP gene promoter in response to scrapie infection.

Animals↗

PubMed2000

ATM is a cytoplasmic protein in mouse brain required to prevent lysosomal accumulation.

We previously generated a mouse model with a mutation in the murine Atm gene that recapitulates many aspects of the childhood neurodegenerative disease ataxia-telangiectasia. Atm-deficient (Atm-/-) mice show neurological defects detected by motor function tests including the rota-rod, open-field tests and hind-paw footprint analysis. However, no gross histological abnormalities have been observed consistently in the cerebellum of any line of Atm-/- mice analyzed in most laboratories. Therefore, it may be that the neurologic dysfunction found in these animals is associated with predegenerative lesions. We performed a detailed analysis of the cerebellar morphology in two independently generated lines of Atm-/- mice to determine whether there was evidence of neuronal abnormality. We found a significant increase in the number of lysosomes in Atm-/- mice in the absence of any detectable signs of neuronal degeneration or other ultrastructural anomalies. In addition, we found that the ATM protein is predominantly cytoplasmic in Purkinje cells and other neurons, in contrast to the nuclear localization of ATM protein observed in cultured cells. The cytoplasmic localization of ATM in Purkinje cells is similar to that found in human cerebellum. These findings suggest that ATM may be important as a cytoplasmic protein in neurons and that its absence leads to abnormalities of cytoplasmic organelles reflected as an increase in lysosomal numbers.

Animals↗

PubMed1999

Expression and targeting to the plasma membrane of xClC-K, a chloride channel specifically expressed in distinct tubule segments of Xenopus laevis kidney.

ClC-K channels are Cl- channels specifically expressed in vertebrate kidneys. Although their heterologous functional expression is still controversial, indirect evidence points to them as major factors involved in Cl- reabsorption in the nephron. We cloned xClC-K, an amphibian (Xenopus) homologue of mammalian ClC-K. The cDNA encodes a 77 kDa protein presenting 62% similarity with human ClC-Kb. The protein is monoglycosylated and is expressed primarily in the Xenopus kidney. It is localized in the basolateral membranes of proximal convoluted tubules of the nephron and in the apical region of the diluting segments. Heterologous expression of xClC-K in HEK-293 cells showed that the full-length protein is glycosylated and targeted to the cell membrane, but no associated Cl- current could be observed with the patch-clamp recording technique. N-glycosylation of both the native kidney channel and the recombinant protein expressed in HEK-293 conferred on them anomalous behaviour in denaturing PAGE, which is indicative of strong interactions at the extracellular side of the plasma membrane. The expression of ClC-K channels in both mesonephric and metanephric kidneys will permit further comparative physiological studies of Cl- permeabilities at the molecular level.

Amidohydrolases↗

PubMed1997

Synaptic beta-amyloid precursor proteins increase with learning capacity in rats.

The precursor proteins of Alzheimer's disease beta-amyloid peptide, the beta-amyloid precursor protein isoforms, comprise a family of neuronal proteins with synaptic localization whose physiological roles in brain are poorly understood. One possible role for synaptic proteins is involvement in neuronal plasticity. After exposure to an enriched environment compared to impoverished conditions, rats exhibited superior cognitive capacity. Up to approximately four-fold increased overall levels of beta-amyloid precursor proteins were found in cortical/subcortical tissue of the enriched animals displaying significantly more synapses immunoreactive for the different beta-amyloid precursor protein isoforms (beta-amyloid precursor protein695- and beta-amyloid precursor protein751/770) in hippocampus and adjacent occipital cortex. This correlation thus provides in vivo evidence for an association of beta-amyloid precursor proteins with plastic changes induced by complex environment with consequences for cognitive functions and suggests that impaired beta-amyloid precursor protein metabolism at synapses might contribute to brain dysfunction in Alzheimer's disease.

Amyloid beta-Protein Precursor↗

PubMed1996

Cerebellar granule cell differentiation in mutant and X-irradiated rodents revealed by the neural adhesion molecule TAG-1.

In the external granular layer of the cerebellum, the granule cell precursors express the transient axonal glycoprotein TAG-1, a molecule involved in adhesion and neurite outgrowth. Granule cells express TAG-1 transiently, just as they extend neurites before migrating over the radial glia. The present study aims to investigate whether the expression pattern of TAG-1 is altered when granule cells develop abnormally. We studied in vivo models in which Purkinje and/or granule cell defects occur during postnatal development. These include the cerebellar mutant mice staggerer and lurcher as well as rats irradiated during postnatal development. Neither alterations in Purkinje cell differentiation nor the related granule cell loss in the mouse mutants impairs the ability of the surviving granule cell precursors to express TAG-1. Also, early granule cell loss in the X-irradiated rats do not disturb the TAG-1 expression phase in the patches of surviving granule cell precursors. Ectopic granule cells found in the adult cerebellum of X-irradiated rats do not bear the molecule, although they are located in the most superficial part of the molecular layer, occupied by the immunopositive cells a few days earlier. Thus, TAG-1 marks a very precise stage of granule cell differentiation, and the inward migration process itself is not required for the cessation of the expression. We postulate that TAG-1 may be involved in local differentiation steps restricted to the deep external granular layer such as parallel migratory routes or synchrony of axonal growth.

Animals↗

PubMed1996

Species specificity of 2-aryl carbapenem-induced immune-mediated hemolytic anemia in primates.

L-695,256 is a novel 2-fluorenonyl carbapenem antibiotic with significant antimicrobial activity against strains of methicillin-resistant Staphylococci. This prototype compound was administered intravenously to rhesus monkeys (Macaca mulatta) at does of 50 or 200 mg/kg/day for 2 weeks to assess toxicity and found to induce a hemolytic anemia characterized by extravascular hemolysis and splenomegaly. A subsequent study in this species in which 100 mg/kg/day was administered i.v. for 4 weeks showed that all animals were direct antiglobulin test (Coombs' test) positive for IgG with 20-25% reductions in the erythron. Following 3 weeks of recovery, the erythron had returned to normal, although it took an additional 2 months for the Coombs' test to become negative. Challenge of these same animals with 0.5 million U/kg (300 mg/kg/day) of penicillin intravenously indicated no apparent cross-reactivity. Since attempts to establish a model for this immune-mediated hemolytic anemia with this drug in rats or mice were unsuccessful, a 2-week i.v. study in squirrel monkeys (Saimiri sciureus) was conducted at a dose of 200 mg/kg/day. All animals in this study remained Coombs' test negative with no changes in the erythron, suggesting an increased sensitivity to beta-lactam-induced anemia in rhesus monkeys compared to other species. Further support for this hypothesis was obtained using the cephalosporin antibiotic, cefotetan. This compound induced a high incidence of Coombs' test positive hemolytic anemia at clinically relevant doses in rhesus monkeys, despite a very low incidence of this adverse effect in patients with many years of clinical use. These data suggest that although rhesus monkeys respond in a qualitatively similar manner to humans with regard to high doses of beta-lactam antibiotics, their sensitivity may overestimate the risk of immune-mediated hemolytic anemia for clinical use.

Anemia, Hemolytic, Autoimmune↗

PubMed1995

5'-nucleotidase activity as a synaptic marker of parasagittal compartmentation in the mouse cerebellum.

In the molecular layer of the mouse cerebellum, the histochemical activity of the adenosine-producing ectoenzyme 5'-nucleotidase discloses a parasagittal pattern of alternating enzyme-rich and enzyme-poor bands. In the rat, 5'-nucleotidase activity transiently labels cerebellar synapses during postnatal development and shifts later on towards an exclusive glial location in the molecular layer. We therefore asked whether different ultrastructural expression of 5'-nucleotidase would account for the light microscopic pattern seen in the adult mouse cerebellum. Using an enzyme cytochemical method, we localized 5'-nucleotidase activity on the glial cells and at the main types of asymmetrical synapses in the developing and mature cerebellum of the mouse. The percentage of labelled synapses increased until adulthood within the 5'-nucleotidase-positive bands. Here, the vast majority (86%) of the synapses were labelled against only 27% within the negative bands in the adult. Thus, 5'-nucleotidase appears as a marker of glia and of Purkinje cell synapses across cerebellar compartments. Changes in purinergic neuromodulation and/or cell adhesion mediated by 5'-nucleotidase across bands might participate in the functional differentiation of the cerebellar parasagittal subsets.

5'-Nucleotidase↗

PubMed1992

Involvement of the N-methyl D-aspartate (NMDA) receptor in synapse elimination during cerebellar development.

In many instances, the establishment of highly specific neuronal connections during development results from the rearrangement of axonal projections through the trimming of exuberant collaterals or the elimination of functional synapses or both. Although the involvement of the N-methyl D-aspartate (NMDA) subtype of the glutamate receptor has been demonstrated in the shaping of axonal arbors, its participation in the process of selective stabilization of synapses remains an open issue. In this study, the effects of chronic in vivo application of D,L-2-amino-5-phosphonovaleric acid (D,L-APV), a selective antagonist of the NMDA receptor, on the synapse elimination process that takes place in the developing cerebellum of the rat have been analyzed. D,L-APV treatment prevented the regression of supernumerary climbing fiber synapses in 49 percent of the recorded Purkinje cells, while the inactive isomer L-APV was ineffective. Thus, activation of the NMDA receptor is a critical step in the regression of functional synapses during development.

2-Amino-5-phosphonovalerate↗

PubMed1992

The neuroepithelial cells of the fish gill filament: indolamine-immunocytochemistry and innervation.

The neuroepithelial cells (NECs) of the fish gill filament share several morphofunctional features with the cells of the neuroepithelial bodies in the lungs of air-breathing vertebrates. In the present study, a detailed indolamine-immunocytochemical analysis of the branchial neuroepithelial cells and nerves was undertaken in non-teleost and teleost species, with particular emphasis on the latter. In the rainbow trout, Oncorhynchus mykiss, the chemical degeneration of either catecholaminergic (by 5- and 6-hydroxydopamines) or indolaminergic (by 5,6-dihydroxy-tryptamine) innervations associated with the NECs was studied using electron microscopy. In teleosts, the NECs are located primarily on the distal half of the filament. In the trout particularly, these cells are innervated mainly by non-indolaminergic nerves taking up sympathetic neurotoxins. The proximal half of the filament contains isolated NECs innervated additionally by intrinsic indolaminergic neurons. Serotonin-like immunoreactivity of the NECs is evident in the granular vesicles packed within the basal soma and processes which surround non-vascular and vascular smooth muscles in the filament. Apical processes from the neuroepithelial cells occasionally contact the water on the surface of the filament epithelium. The secretory function of the NECs is discussed with reference to the probable involvement of serotonin in the modulation of fish gill function. In addition, their connections with both central and branchial nervous systems suggest a possible chemoreceptor role.

Animals↗

PubMed1992

Quantification of 5-hydroxytryptamine1A receptors in the cerebellum of normal and X-irradiated rats during postnatal development.

5-Hydroxytryptamine1A receptors were studied in rats during the first postnatal month in the normal cerebellum and in the granule cell-deprived cerebellum produced by X-irradiation at postnatal day 5. Quantitative autoradiographic studies on sagittal sections of cerebellar vermis, using [1251]BH-8-MeO-N-PAT as radioligand or specific anti-receptor antibodies, revealed that 5-hydroxytryptamine1A receptors existed in the molecular/Purkinje cell layer but at variable density from one lobule to another. Thus, in both normal and X-irradiated rats, the posterior lobules were more heavily labelled than the anterior ones, and the density of 5-hydroxytryptamine1A sites decreased progressively in all the cerebellar folia down to hardly detectable levels at postnatal day 21. However, the intensity of labelling remained higher at postnatal day 8 and postnatal day 12 in X-irradiated rats than in age-paired controls. Measurements of [3H]8-OH-DPAT specific binding to membranes from whole cerebellum confirmed that the density of 5-hydroxytryptamine1A sites per mg membrane protein (Bmax) was higher in X-irradiated animals than in age-paired controls. However, on a "per cerebellum" basis, no significant difference could be detected between the total number of 5-hydroxytryptamine1A sites, which progressively increased in both control and X-irradiated animals during the first postnatal month. These results therefore show that 5-hydroxytryptamine1A receptors are not located on developing granule cells. The progressive decrease in 5-hydroxytryptamine1A receptor density during the first postnatal month did not reflect a transient expression of 5-hydroxytryptamine1A receptors in the cerebellum of newborn rats, but resulted from the progressive "dilution" of these sites in this growing structure. The higher density of 5-hydroxytryptamine1A sites in X-irradiated rats simply reflected a lower "dilution" due to the delayed growth of the cerebellum in these animals.

Aging↗

PubMed1992

Role of the target in synapse elimination: studies in cerebellum of developing lurcher mutants and adult chimeric mice.

As the mature nervous system is sculpted out of its embryonic anlage, regressive events are a surprisingly common feature. As one example, the establishment of adult innervation in the CNS and PNS often involves a massive withdrawal of previously formed functional synapses. In the cerebellum, the one-to-one relationship of inferior olivary climbing fibers to Purkinje cells is preceded by a transient stage in which each Purkinje cell is multiply innervated. The regulation of this regressive event is still not fully understood; previous studies suggested that some stimulus from the maturing granule cells is necessary. We have used the lurcher (Lc) mutation as a model system in which to study this phenomenon. In lurcher mice, Purkinje cells degenerate during the first few postnatal weeks, after receiving synaptic contacts from both inferior olivary neurons and granule cells. We have recorded the climbing fiber responses both in lurcher mutants at postnatal days 14-20 (P14-P20) and in adult lurcher chimeras. In the latter, experimental genetics are used to create a situation in which untreated wild-type Purkinje cells are present in an environment that ranges from 100% wild-type to nearly mutant. We found that in P14-P16 lurcher mutants, most of the cells recorded (75%) remained polyinnervated, whereas in wild-type control mice, only 10% of the Purkinje cells retained their multiple innervation. By P18-20, it was difficult to find Purkinje cells in the lurcher mutants that would withstand an intracellular electrode. Nonetheless, in those cells that were successfully impaled, most remained multiply innervated. By this age in wild-type mice, 100% of the Purkinje cells are monoinnervated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1990

[Synaptic localization of 5'-nucleotidase activity in the cerebellar cortex in adult rats irradiated by X rays after birth].

5'-nucleotidase cytochemistry was performed in the cerebellum of adult rats exposed previously to a single postnatal X-irradiation which maintains until adulthood the normally transient multiple innervation of cerebellar Purkinje cells by climbing fibers. 5'-nucleotidase activity persists in climbing fiber synapses and other asymmetrical synapses while it is transient during normal development. Therefore, in the X-irradiated rat, an immature stage of the excitatory synapses persists which, for the climbing fibers, coïncides with or precedes their involution during normal development.

5'-Nucleotidase↗

PubMed1989

Corneal toxicity studies in rabbits and dogs with hydroxyethyl cellulose and benzalkonium chloride.

Hydroxyethyl cellulose (HEC) is used as a viscosity-enhancing agent in ophthalmic formulations to prolong corneal contact time and increase intraocular drug levels. Benzalkonium chloride (BAK) is the preservative most frequently used in ophthalmic formulations. Corneal epithelial changes were seen by slit lamp and light microscopic examination in rabbits but not dogs after multiple instillations of an ophthalmic vehicle containing 0.01% BAK and 0.5% HEC. Microscopically, there was sloughing of superficial epithelial cells and a slight loss of polarity of the basal cells. Formulations with 0.01% BAK and HEC, at concentrations between 0.3 and 0.8%; caused these changes but not with BAK or HEC alone. It was concluded that hydroxyethyl cellulose increased the viscosity and prolonged the contact time of BAK with cornea resulting in corneal epithelial damage in the rabbit. Physiological and anatomical features of the rabbit combined with the increased contact time were concluded to favor these changes in this species. The results confirm that the rabbit is a sensitive and unique species in studies of ocular toxicity of drugs.

Animals↗

PubMed1982

Neuroepithelial cells in fish gill primary lamellae.

Formaldehyde-induced fluorescence reveals numerous serotonin-containing cells within the primary epithelium of the fish gill. These cells are isolated or clustered and are supported by the epithelial basal lamina. They never reach the external medium and are found on the internal side of the primary lamellae, facing the respiratory water flow. With the electron microscope, these cells are found to contain dense-cored vesicles (DCV) of 80-100 nm. Nerve profiles are consistently found close to DCV cells. After having crossed the basal lamina, nerve fibers form endings on DCV-containing cells. These endings display both small clear vesicles and DCV and are in direct contact with DCV cells. Specific membrane alterations are suggestive of efferent synapses. These cells are considered neuroepithelial cells, similar to those found within the wall of lung airways in mammals and submammalian vertebrates. Structure and localization are suggestive of a tissue O2 sensor.

Animals↗