[Acute levamisole poisoning].
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Acute Disease↗
Biomedical subjects
C Joly
Publications and source records attributed to C Joly.
The G protein-coupling profile of metabotropic glutamate receptors, as determined with exogenous G proteins, is independent of their ligand recognition domain.
Metabotropic glutamate (mGlu), Ca2+-sensing, gamma-aminobutyric acidB, and a large number of pheromone receptors constitute a peculiar family of G protein-coupled receptors. They possess a large extracellular domain that has been proposed to constitute their ligand binding domain. The aim of the current study was to examine whether this large ligand binding domain had any influence on the G protein-coupling selectivity of the receptor, and vice versa. We chose mGlu receptors, which are classified into three groups according to their sequence homology and pharmacology, as representatives of this receptor family. To define a G protein-coupling profile for these receptors, we used a set of exogenous phospholipase C-activating G proteins in the same way that synthetic ligands are used to define agonist and antagonist pharmacological profiles. This set includes Galpha15, Galpha16, Galphaq, and chimeric Galphaq proteins with the last few amino acids of either Galphai2 (Galphaqi), Galphao (Galphaqo), or Galphaz (Galphaqz). Cotransfection of mGlu receptors with these G proteins and examination of their coupling to phospholipase C revealed that group I, II, and III receptors have distinct G protein-coupling profiles. By swapping the extracellular domains of the most distantly related mGlu receptors (the rat group I mGlu1a and the Drosophila melanogaster group II DmGluA receptors), we show that the extracellular domain determines the agonist pharmacological profile and that this domain does not modify the G protein-coupling profile determined by the seven-transmembrane-domain region of mGlu receptors.
Amino Acid Sequence↗
Mechanical correlations derived from segmental histologic study of the equine superficial digital flexor tendon, from foal to adult.
OBJECTIVE: To assess histologic variations of the equine superficial digital flexor tendon (SDFT) according to site and to horse age and activity, and to correlate these data with reported segmental mechanical results. SAMPLE POPULATION: Superficial digital flexor tendons isolated from 42 horses 0.5 hour to 23 years old. PROCEDURE: 7 segments of each SDFT were delimited and submitted for conventional histologic examination. Each segment was examined and graded for fiber undulation, cellularity, number and size of interfascicular connective spaces (ICS), presence or absence of focal and diffuse chondroid metaplasia, and differentiation of the dorsal (DB) and palmar (PB) borders of the tendon. RESULTS: Fiber undulation and cellularity significantly decreased with age. The proximal and middle metacarpal segment fibers were significantly less undulated and their ICS were smaller than those of the other segments, especially in old horses. Focal chondroid metaplasia developed from 5 years onward, mainly in the sesamoidean segments. Diffuse chondroid metaplasia was characteristic of the digital region in horses > 6 years old. The DB of the metacarpodigital region tended to differentiate into fibrocartilage in association with age. The PB was generally differentiated as nonfascicular dense connective tissue. Activity induced a decrease in the number and size of the ICS. CONCLUSIONS: The lesser undulation of the proximal and middle metacarpal segments fibers can be correlated to their mechanical behavior (stress-strain curve) and relative weakness within the SDFT. Focal chondroid metaplasia and fibrocartilage on the DB are normal features, related to the compression stresses undergone by the sesamoidean region of the tendon.
Aging↗
[Peripheral 'man in a barrel' syndrome].
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Anesthesia, General↗
Zygotic expression of the zebrafish Sox-19, an HMG box-containing gene, suggests an involvement in central nervous system development.
The zebrafish Sox-19 belongs to the Sry subfamily of HMG (Hight Mobility Group) box genes and is closely related to the Sox sub-group B, comprising the mouse Sox-1, Sox-2 and Sox-3 genes, with respect to both HMG box homology (95.3%) and neural expression during embryogenesis. Analysis of Sox-19 expression during embryogenesis by whole-mount in-situ hybridization revealed interesting features. In early gastrula embryos, Sox-19 transcripts are detected within a circular area in the region of the presomptive central nervous system (CNS) and appears to be the earliest molecular marker of the CNS in vertebrates. In the developing brain, ZfSox-19 mRNA is distributed in the ventral region of the diencephalon, midbrain and hindbrain whereas the expression is excluded from the telencephalon. In spite of the ventral localisation of its mRNA, the expression of this ZfSox-19 gene is completely normal in cyclops embryos which implies that ZfSox-19 expression is independent of the presence of the floor plate.
Amino Acid Sequence↗
The second intracellular loop of metabotropic glutamate receptor 1 cooperates with the other intracellular domains to control coupling to G-proteins.
Metabotropic glutamate receptors (mGluR) share no sequence homology with any other G-protein-coupled receptors (GPCRs). The characterization of their G-protein coupling domains will therefore help define the general rules for receptor-G-protein interaction. To this end, the intracellular domains of mGluR3 and mGluR1, receptors coupled negatively to adenylyl cyclase and positively to phospholipase C, respectively, were systematically exchanged. The ability of these chimeric receptors to induce Ca2+ signals were examined in Xenopus oocytes and HER 293 cells. The chimeric receptors that still possessed the second intracellular loop (i2) of these proteins were targeted correctly to the plasma membrane. Consistent Ca2+ signals could be recorded only with chimeric mGluR3 receptors that contains i2 and at least one other intracellular domains of mGluR3 have to be replaced by their mGluR1 equivalent to produce optimal coupling to G protein. These observations indicate that i2 of mGluR1 is a critical element in determining the transduction mechanism of this receptor. These results suggest that i2 of mGluRs may play a role similar to i3 of most other GPCRs in the specificity of coupling to the G-proteins. Moreover, as in many other GPCRs, our data revealed cooperation between the different mGluR intracellular domains to control efficient coupling to G-proteins.
Amino Acid Sequence↗
Characterisation of sorbed water molecules on neutral and ionic polysaccharides.
Ionic and neutral polysaccharides with well-defined structures were chosen to investigate the mechanism of water sorption at different relative humidities. From an experimental point of view, the freezing water was determined by DSC when the total sorbed water was obtained from thermogravimetry. The isotherms of sorption and enthalpies of interaction were determined using the combination of a microbalance and a microcalorimeter. It is shown that freezing water appears for P/P(zero) > 0.85 especially with the neutral polymers. The differential molar enthalpy of interaction is higher for P/P(zero) < 0.85 corresponding to the fixation of two water molecules forming double H-bonds; this result is confirmed by molecular modelling; saturation is obtained experimentally for 4 water molecules interacting per glucose unit. On ionic polymers, the water retention increases especially over P/P(zero) approximately 0.8 and the enthalpy of interaction is higher for the first water molecules sorbed. For P/P(zero) approximately equal to 0.8, the numbers of bound water molecules found are 2 per glucopyranosyl unit for neutral polysaccharides, 5 for glucuronan and 9-10 for carboxymethylcellulose (CMC) of DS = 2 and hyaluronan (HA).
Adsorption↗
[Embryonal metabolism].
It is very difficult to have a clear and homogeneous idea of the embryo metabolism. In fact it may vary from one species to another and also according to the embryonic stage: i.e. before and after genomic activation. Basic compounds such as glucose may be toxic, but obviously, it is more the problem of the quantity introduced in the culture media and an unsuitable balance between the metabolites which may impair the embryonic development. At low concentration glucose is actively metabolised by embryos. High levels of amino acids are deleterious (due to release of ammonia), but they are necessary at low concentrations. Addition of serum or other biological fluids is generally useless. Further knowledge on embryo metabolism is necessary to avoid culture medium related delay or developmental blocks. Sequential media are at least partly the answer.
Amino Acids↗
Widespread expression of the eve1 gene in zebrafish embryos affects the anterior-posterior axis pattern.
The zygotic expression of the eve1 gene is restricted to the ventral and lateral cells of the marginal zone. At later stages, the mRNAs are localized in the most posterior part of the extending tail tip. An eve1 clone (pcZf14), containing a poly-A tail, has been isolated. In order to address eve1 gene function, pcZf14 transcript injections into zebrafish embryos have been performed. The injection into uncleaved eggs of a synthetic eve1 mRNA (12 pg), which encodes a protein of approximately 28 kd, produces embryos with anterior-posterior (A-P) axis defects and the formation of additional axial structures. The first category of 24 h phenotypes (87%) mainly displays a gradual decrease in anterior structures. This is comparable to previous phenotypes observed following Xhox3 messenger injection either in Xenopus or in zebrafish that have been classified according to the index of axis deficiency (zf-IAD). These phenotypes result in anomalies of the development of the neural keel, from microphthalmia to acephaly. The second category (13%) corresponds to the phenotypes described above together with truncal or caudal supernumerary structures. Additional truncal structures are the most prominent of these duplicated phenotypes, displaying a "zipper" shape of axial structures including neural keels and notochords. Caudal duplication presents no evident axis supernumerary structures. The observation of these phenotypes suggests an important role for the eve1 gene in mesodermal cell specification and in the development of the posterior region, and more particularly of the most posterior tail tip where endogenous eve1 messengers are found.
Amino Acid Sequence↗
The metabotropic glutamate receptors: their second intracellular loop plays a critical role in the G-protein coupling specificity.
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Amino Acid Sequence↗
Molecular, functional, and pharmacological characterization of the metabotropic glutamate receptor type 5 splice variants: comparison with mGluR1.
The main excitatory neurotransmitter in the brain, glutamate (Glu), activates not only receptor-channels, but also receptors coupled to G-protein called metabotropic Glu receptors (mGluRs). Eight genes coding for mGluRs have been characterized to date giving rise to even more proteins due to alternative splicing phenomena. Here we characterized a splice variant of mGluR5, called mGluR5b which contains a 32 amino acid fragment inserted in the cytoplasmic tail, 50 residues after the 7th transmembrane domain. mGluR5b mRNAs are present in different regions of the adult rat brain and are expressed at a higher level than mGluR5a mRNA. Functional analysis of mGluR5a and mGluR5b revealed that they share all the properties of mGluR1a, but not those of mGluR1b or 1c. Like mGluR1a, both mGluR5a and mGluR5b activate a rapid and transient current in Xenopus oocytes. When expressed in LLC-PK1 cells, they show the same subcellular distribution as mGluR1a, and stimulate both inositol phosphate (IP) and cAMP production. Moreover, cells expressing mGluR5a or mGluR5b, like those expressing mGluR1a have a higher basal PLC activity that is not inhibited by glutamate-pyruvate transaminase (GPT), suggesting that these receptors have an intrinsic activity. Interestingly, the pharmacological profiles of mGluR5a and b are identical, but different from that of mGluR1a. Most agonists, except glutamate, are more potent on mGluR5a/b than on mGluR1a. Interestingly, the mGluR1a antagonists MCPG and 4CPG have no effect on mGluR5a/b; 4C3HPG which is a full antagonist at mGluR1a is a partial agonist at mGluR5a/b. These results indicate that the long C-terminal intracellular domain present only in mGluR1a and mGluR5a/b, although not well conserved, is likely to be involved in the specific functional properties of these receptors. Although the ligand recognition sites of mGluR5a/b and mGluR1a are highly conserved, these receptors have different pharmacology.
Alternative Splicing↗
Domains involved in the specificity of G protein activation in phospholipase C-coupled metabotropic glutamate receptors.
G protein-coupled glutamate receptors (mGluR) have recently been characterized. These receptors have seven putative transmembrane domains, but display no sequence homology with the large family of G protein-coupled receptors. They constitute therefore a new family of receptors. Whereas mGluR1 and mGluR5 activate phospholipase C (PLC), mGluR2, mGluR3, mGluR4 and mGluR6 inhibit adenylyl cyclase (AC) activity. The third putative intracellular loop, which determines the G protein specificity in many G protein-coupled receptors, is highly conserved among mGluRs, and may therefore not be involved in the specific recognition of G proteins in this receptor family. By constructing chimeric receptors between the AC-coupled mGluR3 and the PLC-coupled mGluR1c, we report here that both the C-terminal end of the second intracellular loop and the segment located downstream of the seventh transmembrane domain are necessary for the specific activation of PLC by mGluR1c. These two segments are rich in basic residues and are likely to be amphipathic alpha-helices, two characteristics of the G protein interacting domains of all G protein-coupled receptors. This indicates that whereas no amino acid sequence homology between mGluRs and the other G protein-coupled receptors can be found, their G protein interacting domains have similar structural features.
Amino Acid Sequence↗
Widespread expression of the Xenopus homeobox gene Xhox3 in zebrafish eggs causes a disruption of the anterior-posterior axis.
The widespread expression of the Xenopus homeobox gene Xhox3 in zebrafish was performed by microinjection of synthetic Xhox3 mRNA into uncleaved fertilized eggs and resulted in embryos displaying varying degrees of anterior-posterior (A-P) axis disruption. The phenotype observed was dose-dependent and showed anomalies, mainly in neural keel development, from microphthalmia to acephaly. Injection of 5 pg to 10 pg of mRNA caused a range of phenotypes in prim 5 stage embryos from normal to acephalic. Anomalies have been categorized according to an index of axis deficiency (Zf-IAD). We further characterized the axis disturbance by analyzing the expression of two genes implicated in axis formation: engrailed (eng) and brachyury (ntl). eng could not be detected in the muscle pioneer cells of embryos injected with Xhox3. The pattern distribution of brachyury (Ntl) protein is abnormal in Xhox3 injected embryos. Evidence for the conservation of the NH2 terminal region of the Xhox3 protein in frogs and fish is provided by the detection of a nuclear Xhox3-like protein in 24 h zebrafish embryos located in posterior mesoderm tissue. Previous results in Xenopus embryo research and the data presented here support the conservation of an A-P patterning mechanism involving the Xhox3 gene.
Animals↗
The ventral and posterior expression of the zebrafish homeobox gene eve1 is perturbed in dorsalized and mutant embryos.
We have identified and characterized zebrafish eve1, a novel member of the Drosophila even-skipped (eve) gene family. eve1 RNAs are expressed initially in late blastulae with a peak during the gastrula stage, at which time expression is confined to ventral and lateral cells of the marginal zone of the zebrafish embryo. Later, eve1 transcripts are located in the most posterior part of the extending tail tip. We show that LiCl, known to dorsalize Xenopus embryos, has the same effect in zebrafish, resulting in embryos with exaggerated dorsoanterior structures. In LiCl-treated embryos, eve1 transcripts are completely absent. eve1 is therefore a marker of ventral and posterior cells. In the light of its ventroposterior expression domain, the localization of eve1 transcripts was analysed in spadetail (spt) and no tail (ntl), two mutants with abnormal caudal development. In sptb140 homozygous mutants, there is an accumulation of cells in the tail region, resulting from inadequate migratory behaviour of precursors to the trunk somites. These cells, in their abnormal environment, express eve1, emphasizing the correlation between ventroposterior position and eve1 expression. In homozygous mutant embryos for the gene ntl (the homologue of mouse Brachyury, originally called Zf-T), posterior structures are missing (M. E. Halpern, C. B. Kimmel, R. K. Ho and C. Walker, 1993; Cell In press). While mutant and wild-type embryos do not differ in their eve1 transcript distribution during gastrulation, eve1 expression is absent in the caudal region of mutant ntl embryos during early somitogenesis, indicating a requirement for ntl in the maintenance of eve1 expression during tail extension. Our findings suggest that eve1 expression is correlated with a ventral and posterior cell fate, and provide first insights into its regulation.
Amino Acid Sequence↗
[Ventral and posterior expression of the homeo box gene eve1 in zebrafish (Brachydanio rerio) is repressed in dorsalized embryos].
We have identified and characterized the zebrafish eve1 homeo box gene, a member of the Drosophila even-skipped (eve) gene family. eve1 is expressed in the most posterior part of the tail bud during somitogenesis. During gastrulation, transcripts are confined to ventral and lateral cells of the marginal zone of the embryo. We show that LiCl, known to dorsalize Xenopus embryos, has the same effect in zebrafish embryos. In LiCl-treated embryos, eve1 transcripts are completely absent, suggesting that eve1 marks the ventral specification of mesoderm in zebrafish gastrulae.
Animals↗
Pro-melanin-concentrating hormone gene (PMCH) is localized on human chromosome 12q and rat chromosome 7.
Melanin-concentrating hormone (MCH) is a cyclic neuropeptide that may be involved in regulation of the stress response and food intake behavior in mammals. MCH and two other putative neuropeptides, NEI and NGE, are encoded by the same precursor, designated pro-melanin-concentrating hormone (PMCH). A panel of somatic cell hybrids segregating either human or rat chromosomes was used to determine the chromosomal localization of the PMCH locus. It was assigned to human chromosome 12q and to rat chromosome 7. This is the first neuropeptide-encoding gene found in this new synteny group conserved in rat and human.
Animals↗
Effects of 1,2-propanediol on the cytoskeletal organization of the mouse oocyte.
The effects of 1,2-propanediol, a cryoprotectant used for the freezing of embryos, were tested on the organization of microtubules and microfilaments in mouse oocytes arrested in metaphase II. At low doses (less than or equal to 1.0 M), 1,2-propanediol induced disorganization of the meiotic spindle but at 1.5 M and higher, it stabilized the spindle. Cytoplasmic asters were observed at all doses tested. An extensive network of free microtubules was observed at 1.0 M and 2.0 M 1,2-propanediol, the former having the stronger disruptive effect on the spindle. Higher doses of 1,2-propanediol (greater than or equal to 1.5 M) caused the oocytes to form cytoplasmic blebs. These blebs lacked detectable cortical microfilaments. In contrast, the microfilament-rich area of the cell cortex overlying the meiotic spindle was not modified.
Actin Cytoskeleton↗
Anti-HPA-4b (anti-Yuk(a)) neonatal alloimmune thrombocytopenia: first report in a Caucasian family.
Neonatal alloimmune thrombocytopenia (NAIT) is caused by platelet antigen incompatibility between the mother and fetus. NAIT is mainly due to alloimmunization; the frequency varying among ethnic groups. In Caucasians HPA-1a is the antigen most frequently implicated. In Japan, NAIT due to anti-HPA-4b antibody has already been described, but this is the first case to be reported in Caucasians.
Adult↗