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C Dechesne

Publications and source records attributed to C Dechesne.

18 recordsLinked to original sources
PubMed1999

The genexpress IMAGE knowledge base of the human muscle transcriptome: a resource of structural, functional, and positional candidate genes for muscle physiology and pathologies.

Sequence, gene mapping, and expression data corresponding to 910 genes transcribed in human skeletal muscle have been integrated to form the muscle module of the Genexpress IMAGE Knowledge Base. Based on cDNA array hybridization, a set of 14 transcripts preferentially or specifically expressed in muscle have been selected and characterized in more detail: Their pattern of expression was confirmed by Northern blot analysis; their structure was further characterized by full-insert cDNA sequencing and cDNA extension; the map location of the corresponding genes was refined by radiation hybrid mapping. Five of the 14 selected genes appear as interesting positional and functional candidate genes to study in relation with muscle physiology and/or specific orphan muscular pathologies. One example is discussed in more detail. The expression profiling data and the associated Genexpress Index2 entries for the 910 genes and the detailed characterization of the 14 selected transcripts are available from a dedicated Web server at. The database has been organized to provide the users with a working space where they can find curated, annotated, integrated data for their genes of interest. Different navigation routes to exploit the resource are discussed.

Base Sequence↗
PubMed1992

Isolation and functional comparison of Dmyd, the Drosophila homologue of the vertebrate myogenic determination genes, with CMD1.

We have isolated a cDNA clone, called Dmyd for Drosophila myogenic determination gene, from a 0-16 hour Drosophila embryo library that encodes a protein with structural and functional characteristics similar to the members of the vertebrate MyoD family (Paterson et al 1991). Dmyd encodes a polypeptide of 332 amino acids with 82% identity to MyoD in the 41 amino acids of the putative helix-loop-helix region and 100% identity in the 13 amino acids of the basic domain proposed to contain the essential recognition code for muscle specific gene activation. The gene is unique and maps to 95A/B on the right arm of the third chromosome. Low stringency hybridizations indicate Dmyd is not a member of a multigene family, similar to MyoD in vertebrates. Dmyd is a nuclear protein in Drosophila, consistent with its role as a nuclear gene regulatory factor, and is proposed to be a transiently expressed marker for a unique subset of muscle founder cells. We have used an 8kb promoter fragment from the gene, which contains the first 55 amino acids of the Dmyd protein, joined to lac Z to follow myogenic precursor cells into muscle fibers using antibodies to beta-galactosidase and Dmyd. Unlike the myogenic factors in vertebrate muscle cells, Dmyd appears to be expressed at a much lower level in differentiated Drosophila muscles so it cannot be followed continuously as a muscle marker. This is reflected in the loss of expression of Dmyd RNA in 12-24 hour embryos, a major period of early myogenesis, as well as in the undetectable level of the nuclear antigen in primary cultures of embryonic and adult Drosophila muscle. Functional differences between Dmyd and CMD1 are described and explained in terms of a model which may give insight to the nature of homo and heterodimer formation in the bHLH family of proteins.

Amino Acid Sequence↗
PubMed1988

Histochemistry of ventricular heavy-chain myosins in cardiomyopathic Syrian hamsters treated with D-600.

Monoclonal antibodies (MAb) have been used to study the distribution of ventricular heavy-chain (HC) myosins in cardiomyopathic UM-X7.1 Syrian hamsters. The Ab were identified as alpha and beta anti-HC myosins because of their ability to cross-react with ventricular V1 and V3 myosins, respectively. Cryostat frozen sections from the midventricle region of normal and myopathic hearts were processed for demonstration of these isomyosins by indirect immunofluorescence. In myopathic hearts, there was a shift of predominant alpha myosin toward the beta isoform with the time course of the hamster cardiomyopathy. A D-600 treatment while preventing cardiac necrotic lesions had little or no effect on the beta isomyosin conversion. It is inferred that the isomyosin shift during the progression of the hamster cardiomyopathy is unrelated to the necrotizing process and merely reflects the hypokynetism of the cardiomyocytes.

Animals↗
PubMed1986

Effects of hypothyroidism on postnatal development in the peripheral vestibular system.

The morphogenetic effects of congenital hypothyroidism on the development of rat vestibular receptor cells and ganglia were investigated by transmission electron microscopy. Vestibular ganglia are especially immature and characterized by an absence of a myelin sheath around the perikarya. The type I hair cells have a delayed development in their innervation. The last cells to differentiate and the last synaptic contacts to develop are the most affected. The most remarkable result of hypothyroidism is the persistent immaturity of the synaptic contacts.

Animals↗
PubMed1985

Fractionation and characterization of two molecular variants of myosin from adult human atrium.

Monoclonal antibodies (MAb) to myosin heavy chains were prepared from one adult human ventricular myocardium. Several of these MAb reacted by indirect immunofluorescence in a heterogenous way on cryostat transverse sections of fibers from human atrial myocardium, suggesting the presence of different forms of myosin within the human atrium and prompting the further use of the MAb to attempt to fractionate preparations of native atrial myosins. Two molecular variants of human atrial myosins or myosin fragments were thus separated by immunoaffinity chromatography performed with one antiventricular myosin MAb. Seven MAb located at different positions along the myosin heavy chains, as deduced from blotting and immuno-electron microscopy experiments, were used to characterize the structural relationships between the separated human atrial isomyosins and between each of them and the main human ventricular myosin. As deduced from competitive radioimmunoassay measurements, the primary structures of the two atrial myosins differ in at least five antigenic determinants and share at least two of them; similarly located structural differences were observed between one of the atrial myosins and the ventricular myosin. Conversely, the primary structures of the other atrial myosin and of the ventricular myosin differ in at least two antigenic determinants and share at least five of them. Differences in the primary structures of the human cardiac myosins were confirmed by analysis of the peptides produced by limited enzymatic digestion of the heavy chains; a few peptide differences were consistently found. To summarize the two separated forms of atrial myosin have different heavy chains, but they have similar if not identical in vitro ATPase activities and the same light chains. One of the atrial myosins is immunologically close to the ventricular myosin, but they each differ with respect to their heavy chains, light chains, and enzymatic activities.

Adenosine Triphosphatases↗
PubMed1985

Early development of vestibular receptors in human embryos. An electron microscopic study.

The development of the vestibular receptors in 7 to 9-week-old human embryos was investigated by light, scanning and transmission electron microscopy. The greater part of the vestibular epithelium is undifferentiated in the 7-week-old embryo. It is composed of polystratified epithelial cells. Some afferent endings are found at the base of the epithelial cells but no synaptic specializations are detected. A few afferent endings reach the upper part of the epithelium. Thus, at this stage the fibers are present in the vestibular epithelium before the differentiation of the sensory cells. The apical pole of the epithelial cells presents basal bodies linked with striated rootlets and other typical vestibular epithelium cell structures. Short hair bundles are found in a very small part of the vestibular epithelium. At 8-9 weeks of gestation, numerous nerve endings surround the base of the sensory cells. Densifications of the pre- and postsynaptic membranes and synaptic bodies are seen. The newly afferented cells present polarized hair bundles. We suspect that the hair cells are important for the guidance of afferent terminals perhaps even before their morphological differentiation.

Cell Differentiation↗
PubMed1985

[Development of the internal ear during the 1st trimester of pregnancy. Differentiation of the sensory cells and formation of the 1st synapses].

The inner ear of seventeen embryos, aged from 7 to 14 weeks after the fecondation, was investigated by optic and electron (transmission and scanning) microscopy. The timing of the first stages of the auditory and vestibular human receptor development is similar to the timing reported in animal studies, the vestibular epithelium development preceding by 2 to 3 weeks the cochlear development. The nerve fibers enter the sensory epithelia before the hair cell differentiation was histologically observed. At 9 weeks in the vestibular organs and 11 weeks in the cochlea, the hair cells are well differentiated and they exhibit typical synapses with nerve endings. Very early in the embryonic life, the auditory and vestibular receptors start their maturation and establish their connections with the peripheral and central nervous system; this indicates that the third month of pregnancy is a particularly sensitive period as far as the inner ear development is concerned.

Cell Communication↗
PubMed1984

The efferent vestibular system in the cat: a horseradish peroxidase and fluorescent retrograde tracers study.

Neurons of the efferent vestibular system were investigated in the cat using retrograde axonal transport of horseradish peroxidase and fluorescent retrograde double labelling techniques. The number of efferent neurons was clearly higher than previously reported. A three dimensional reconstruction of the location of these neurons showed that they constitute a single group and did not give evidence of an eventual specialization based on neuron subpopulations. However, a study of cross-sectional areas of the horseradish peroxidase-labelled efferent neurons detected that the ipsilateral population contained a larger number of small neurons than the contralateral one. Double labelling by means of either 4',6-diamidino-2- phenylindol 2HCl in combination with horseradish peroxidase or Fast Blue in combination with Nuclear Yellow showed that 20% of efferent neurons project to both labyrinths. Such a high percentage raises the question of the role of these double-projecting cells and the specificity of their branching on vestibular receptors. This study expands previous work in the cat demonstrating that a much greater number of efferent neurons exists than had hitherto been assumed, among them 20% have both crossed and uncrossed projections.

Animals↗
PubMed1984

Characterization and distribution of myosin variants in normal and pathological human hearts.

Hybridomas were prepared from mice immunized with myosin from the enlarged left ventricle of a 53-year-old female bearing an obstructive cardiomyopathy. With several different experimental approaches using anti-myosin antibodies, at least two subpopulations of atrial and at least two subpopulations of ventricular myosin were detected, characterized and located in normal human hearts. The human atrium and human ventricle each contained small zones of myosin variation which were scattered, but probably not randomly distributed, within a large area of myocardium whose cellular distribution of myosin was constant. Recent applications of the same approach to the study of the regional variations of the different myosin forms within two pathological human hearts are discussed.

Adenosine Triphosphatases↗
PubMed1984

Fiber types and myosin types in human atrial and ventricular myocardium. An anatomical description.

Hybridomas were prepared from mice immunized with myosin from the enlarged left ventricle of a 53-year-old female with an obstructive cardiomyopathy. The specificity of 15 monoclonal antibodies to myosin heavy chains was assessed by the reactivity of muscle extracts and of chymotryptic myosin fragments of different sizes with these antibodies, as determined by the immune replicate technique; some of the monoclonal antibodies cross-reacted only with the ventricular V3-type myosin from hypothyroid rats, whereas the other antibodies cross-reacted both with the latter and with the ventricular V1-type myosins from normal young rats. Immunological heterogeneity of the fibers from human atrial muscles and from human ventricular muscles was detected by some of the antimyosin antibodies by means of indirect immunofluorescence. Histochemical fiber heterogeneity was also detected by adenosine triphosphatase staining of the same tissues. Because of the close correspondence observed between the immunological and histochemical responses of atrial fibers, it has been postulated that at least two distinct types of myosin exist in the human atrium, each myosin form being histochemically related to either alpha- or beta-like ventricular myosin heavy chains. In contrast, there was no direct correspondence between the two experimental approaches in human ventricles, and it is postulated that at least three distinct types of myosin exist within the human ventricles, one V1-type myosin, presumably corresponding to the very rare fibers with an alkaline-stable adenosine triphosphatase activity, and two other V3-type myosins corresponding to immunologically different fibers, each having an alkaline-labile adenosine triphosphatase activity. Monoclonal antibodies that can distinguish among the different myosin variants were further used to provide the basis for an anatomical description of fiber types and myosin types within the human atrial and ventricular myocardium in the whole hearts of two young boys who died sudden violent deaths. Small zones of myosin variation were seen to be scattered, but probably not randomly distributed, within large areas of myocardium in which the cellular distribution of myosin was constant; the large areas had one myosin distribution specific for each cardiac cavity. No clear-cut conclusions can yet be made concerning the physiological role of the regional variations observed in the distribution of the different molecular forms of myosin.

Adenosine Triphosphatases↗
PubMed1983

Structural differences between atrial and ventricular myosins from normal human hearts.

Comparisons were made between myosins isolated from the right and left ventricles and the atria of normal human hearts. Parameters examined included electrophoretic mobilities of native molecules, K+ and Ca2+ dependent enzymatic activities, light chain composition, peptide patterns from partial proteolytic digests of entire heavy chains or rods, and maps of complete digests of specific 21 and 25 kilodalton heavy chain fragments. Human ventricular and atrial myosins differ in all parameters except in the charge of molecules. Structural differences between cardiac myosins derived from the two sources were apparent in both the head and tail portions of the heavy chains. With respect to the above parameters no differences were found between myosins from left and right human ventricles.

Adenosine Triphosphatases↗
PubMed1980

Control of the vestibular nerve activity by the efferent system in the cat.

The effect of vestibular efferent system stimulation on the vestibular action potential (VAP) recorded after brief mechanical ampullopetal stimulation of the lateral canal crista was studied in the cat. When an inhibitory action was recorded it had an effect on the VAP component N2 potential and was also characterized by a positive post potential. When stimulation seemed to have no effect, computer averaging showed a weak facilitating action affecting the N1 potential. The hypothesis of a double efferent system is discussed.

Animals↗
PubMed1979

A new stimulation technique of the crista ampullaris of the lateral canal in the adult cat: study of the action potential of the vestibular nerve.

The stimulation of the crista ampullaris of the lateral canal by a short ampullopetal liquid flux produces on the pre-ganglionic vestibular fibres the appearance of a bimodal action potential. The amplitude of this action potential increases with the intensity of the stimulation. This stimulation also provokes the birth of an evoked potential at the level of the vestibular nuclei as well as an ocular jerk.

Action Potentials↗
PubMedDate not supplied

Action of glutamate in the cat labyrinth.

Glutamate solutions of either 50 mM applied on the membranous labyrinth or 1 mM perfused into the lateral canal in cats increased spontaneous and stimulus-evoked activity of vestibular neurons. Kainic acid (10(-4) M) perfused into the labyrinth produced a depolarizing action on vestibular afferents. These results indicate that glutamate could be an excitatory neurotransmitter at the synapse between vestibular hair cells and afferent nerve fibers in the cat.

Action Potentials↗
PubMedDate not supplied

Postnatal development of vestibular receptor surfaces in the rat.

The development of vestibular receptor surfaces was studied during the postnatal period in the rat on the 1st, 7th, 13th, 32nd and 75th days after birth. Cristae and utricles increase and change their shapes, up to day 13 for the cristae and day 32 for the utricles. Cristae hair bundles are less developed than those of the utricles on the 1st day after birth, with evidence of ciliogenesis being present in the cristae. There is an increase in hair bundle length in both organs that appears complete by the 32nd day after birth. These results are discussed in relation to the ultrastructural and electrophysiological studies concerning the postnatal maturation of the vestibular receptors.

Animals↗