Biomedical subjects

M Parmentier

Publications and source records attributed to M Parmentier.

At least 37 records · Page 2Linked to original sources

PubMed1999

Immunolocalization of a tachykinin-receptor-like protein in the central nervous system of Locusta migratoria migratorioides and neobellieria bullata.

Antisera raised against two distinct peptide regions of the Drosophila neurokinin-like receptor NKD were used to immunolocalize tachykinin-receptor-like proteins in the central nervous system of two insect species: the African migratory locust, Locusta migratoria, and the gray fleshfly, Neobellieria bullata. The resulting immunopositive staining patterns were identical for both antisera. Moreover, a very similar distribution of the immunoreactive material was observed in fleshflies and locusts. Immunoreactivity was found in nerve terminals of the retrocerebral complex, suggesting a presynaptic localization of the receptor in this part of the brain. Cell bodies were stained in the subesophageal ganglion: an anterior group of four larger cells and a posterior group of about 20 cells. These cells have axons projecting into the contralateral nervus corporis allati (NCA) II, bypassing the corpus allatum and projecting through the NCA I into the storage part of the corpus cardiacum. In the glandular part of the corpus cardiacum, the glandular adipokinetic hormone-producing cells did not show any immunopositive staining. In the locust, additional immunopositive staining was observed in internolaterally located neurons of the tritocerebrum and in important integrative parts of the neuropil such as the central body and the mushroom bodies.

Abdomen↗

PubMed1999

Impaired motor coordination and Purkinje cell excitability in mice lacking calretinin.

In 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.

Aging↗

PubMed1999

CD26/dipeptidyl-peptidase IV down-regulates the eosinophil chemotactic potency, but not the anti-HIV activity of human eotaxin by affecting its interaction with CC chemokine receptor 3.

Chemokines attract and activate distinct sets of leukocytes. The CC chemokine eotaxin has been characterized as an important mediator in allergic reactions because it selectively attracts eosinophils, Th2 lymphocytes, and basophils. Human eotaxin has a penultimate proline, indicating that it might be a substrate for dipeptidyl-peptidase IV (CD26/DPP IV). In this study we demonstrate that eotaxin is efficiently cleaved by CD26/DPP IV and that the NH2-terminal truncation affects its biological activity. CD26/DPP IV-truncated eotaxin(3-74) showed reduced chemotactic activity for eosinophils and impaired binding and signaling properties through the CC chemokine receptor 3. Moreover, eotaxin(3-74) desensitized calcium signaling and inhibited chemotaxis toward intact eotaxin. In addition, HIV-2 infection of CC chemokine receptor 3-transfected cells was inhibited to a similar extent by eotaxin and eotaxin(3-74). Thus, CD26/DPP IV differently regulates the chemotactic and antiviral potencies of eotaxin by the removal of two NH2-terminal residues. This physiological processing may be an important down-regulatory mechanism, limiting eotaxin-mediated inflammatory responses.

Anti-HIV Agents↗

PubMed1999

Epitope mapping of CCR5 reveals multiple conformational states and distinct but overlapping structures involved in chemokine and coreceptor function.

The chemokine receptor CCR5 is the major coreceptor for R5 human immunodeficiency virus type-1 strains. We mapped the epitope specificities of 18 CCR5 monoclonal antibodies (mAbs) to identify domains of CCR5 required for chemokine binding, gp120 binding, and for inducing conformational changes in Env that lead to membrane fusion. We identified mAbs that bound to N-terminal epitopes, extracellular loop 2 (ECL2) epitopes, and multidomain (MD) epitopes composed of more than one single extracellular domain. N-terminal mAbs recognized specific residues that span the first 13 amino acids of CCR5, while nearly all ECL2 mAbs recognized residues Tyr-184 to Phe-189. In addition, all MD epitopes involved ECL2, including at least residues Lys-171 and Glu-172. We found that ECL2-specific mAbs were more efficient than NH2- or MD-antibodies in blocking RANTES or MIP-1beta binding. By contrast, N-terminal mAbs blocked gp120-CCR5 binding more effectively than ECL2 mAbs. Surprisingly, ECL2 mAbs were more potent inhibitors of viral infection than N-terminal mAbs. Thus, the ability to block virus infection did not correlate with the ability to block gp120 binding. Together, these results imply that chemokines and Env bind to distinct but overlapping sites in CCR5, and suggest that the N-terminal domain of CCR5 is more important for gp120 binding while the extracellular loops are more important for inducing conformational changes in Env that lead to membrane fusion and virus infection. Measurements of individual antibody affinities coupled with kinetic analysis of equilibrium binding states also suggested that there are multiple conformational states of CCR5. A previously described mAb, 2D7, was unique in its ability to effectively block both chemokine and Env binding as well as coreceptor activity. 2D7 bound to a unique antigenic determinant in the first half of ECL2 and recognized a far greater proportion of cell surface CCR5 molecules than the other mAbs examined. Thus, the epitope recognized by 2D7 may represent a particularly attractive target for CCR5 antagonists.

Amino Acid Sequence↗

PubMed1999

Unresponsiveness to cannabinoids and reduced addictive effects of opiates in CB1 receptor knockout mice.

The function of the central cannabinoid receptor (CB1) was investigated by invalidating its gene. Mutant mice did not respond to cannabinoid drugs, demonstrating the exclusive role of the CB1 receptor in mediating analgesia, reinforcement, hypothermia, hypolocomotion, and hypotension. The acute effects of opiates were unaffected, but the reinforcing properties of morphine and the severity of the withdrawal syndrome were strongly reduced. These observations suggest that the CB1 receptor is involved in the motivational properties of opiates and in the development of physical dependence and extend the concept of an interconnected role of CB1 and opiate receptors in the brain areas mediating addictive behavior.

Analgesics, Opioid↗

PubMed1999

Differential responsiveness to constitutive vs. inducible chemokines of immature and mature mouse dendritic cells.

Upon exposure to immune or inflammatory stimuli, dendritic cells (DC) migrate from peripheral tissues to lymphoid organs, where they present antigen. The molecular basis for the peculiar trafficking properties of DC is largely unknown. In this study, mouse DC were generated from CD34+ bone marrow precursors and cultured with granulocyte-macrophage-CSF and Flt3 ligand for 9 days. Chemokines active on immature DC include MIP1alpha, RANTES, MIP1beta, MCP-1, MCP-3, and the constitutively expressed SDF1, MDC, and ELC. TNF-alpha-induced DC maturation caused reduction of migration to inducible chemokines (MIP1alpha, RANTES, MIP1beta, MCP-1, and MCP-3) and increased migration to SDF1, MDC, and ELC. Similar results were obtained by CD40 ligation or culture in the presence of bacterial lipopolysaccharide. TNF-alpha down-regulated CC chemokine receptor (CCR)1, CCR2, and CCR5 and up-regulated CCR7 mRNA levels, in agreement with functional data. This study shows that selective responsiveness of mature and immature DC to inducible vs. constitutively produced chemokines can contribute to the regulated trafficking of DC.

Animals↗

PubMed1999

Distribution of the nociceptin and nocistatin precursor transcript in the mouse central nervous system.

The distribution of prepronociceptin messenger RNA, the recently identified endogenous ligand of the ORL1 receptor (opioid receptor-like-1), has been studied in the adult mouse central nervous system using in situ hybridization. Prepronociceptin is a new peptide precursor that generates, upon maturation, at least three bioactive peptides: nociceptin, noc2 and the recently described nocistatin. Considering both the density of labeled neurons per region and their intensity of labeling, the distribution of prepronociceptin messenger RNA-containing neurons can be summarized as follows: the highest level of prepronociceptin messenger RNA expression was detected in the septohippocampal nucleus, bed nucleus of the stria terminalis, central amygdaloid nucleus, and in selective thalamic nuclei such as the parafascicular, reticular, ventral lateral geniculate and zona incerta. High to moderate levels of prepronociceptin messenger RNA expression were detected in the lateral, ventral and medial septum, and were evident in brainstem structures implicated in descending antinociceptive pathways (e.g., the gigantocellular nucleus, raphe magnus nucleus, periaqueductal gray matter), and also observed in association with auditory relay nuclei such as the inferior colliculi, lateral lemniscus nucleus, medioventral preolivary nucleus and lateral superior nucleus. A moderate level of prepronociceptin messenger RNA expression was observed in the medial preoptic nucleus, ventromedial preoptic nucleus, periventricular nucleus, pedonculopontine tegmental nucleus, solitary tract nucleus and spinal trigeminal nucleus. A weak level of prepronociceptin messenger RNA expression was present in some areas, such as the cerebral cortex, endopiriform cortex, hippocampal formation, medial amygdaloid nucleus, anterior hypothalamic area, medial mammillary hypothalamic nuclei, retrorubral field and substantia nigra pars compacta. No labeled cells could be found in the caudate-putamen, nucleus accumbens and ventral tegmental area. The present data confirm that nociceptin is expressed in a broad array of regions of the central nervous system. In good correlation with the presently known physiological actions of nociceptin, they include, amongst others, brain areas conveying/integrating pain and auditory sensory afferences.

Animals↗

PubMed1999

Functionality of nutrients and thermal treatments of food.

Since discovering fire man has used heat to modify the sensory properties and to preserve foodstuffs. Nutrients are involved in a number of reactions induced by this form of treatment. Some of these reactions are desirable, e.g. the improvement in the digestibility and the attractiveness of a food. Some reactions are undesirable because they lead to considerable nutritional loss or may result in the formation of mutagenic and carcinogenic molecules. The present paper reviews recent studies in which most of the modifications generated by thermal treatments at both the industrial and domestic level are demonstrated. We focus on the processes and the importance of thermal treatments used currently, as well as the necessity for optimization to minimize undesirable effects.

Food↗

PubMed1999

Expression of P2Y receptors in cell lines derived from the human lung.

1. Northern blotting experiments have been performed with RNA extracted from several cell lines derived from the human lung in order to detect P2Y1, P2Y2, P2Y4 and P2Y6 mRNA. We have investigated the 1HAEo- and 16HBE14o- epithelial cell lines derived from the airway epithelium, the A549 cell line displaying properties of type II alveolar epithelial cells, the CALU-3 serous cells, the 6CFSMEo- submucosal cells and the HASMSC1 airway smooth muscle cells. We have also evaluated one pancreatic epithelial cell line called CFPAC-1. These experiments revealed that P2Y2 and P2Y6 mRNA are co-expressed in the IHAEo-, 16HBE14o- and A549 epithelial cell lines. The CFPAC-1 pancreatic cell line was strongly positive for the P2Y2 receptor. No signal was obtained for the P2Y1 and P2Y4 receptors. 2. We have then performed RT-PCR experiments with specific oligonucleotides of these last two P2Y receptors with the RNA used for the Northern blotting experiments. P2Y4 mRNA was detected in five cell lines: 1HAEo-, 16HBE14o-, 6CFSMEo-, HASMSC1 and CFPAC-1. P2Y1 mRNA was only detected in the CALU-3 cell line. 3. Inositol trisphosphates assays have identified a response typical of the P2Y2 receptor in the 1HAEo- and the 16HBE14o- airway epithelial cell lines which co-express P2Y2 and P2Y6 mRNA. By contrast, the 6CFSMEo- submucosal cells expressed a UTP-specific response which displayed pharmacological characteristics compatible with the human P2Y4 receptor: in particular, there was no response to UDP or ATP and the UTP effect was totally inhibited by pertussis toxin.

Animals↗

PubMed1999

Human P2Y2 receptor polymorphism: identification and pharmacological characterization of two allelic variants.

1. In the process of cloning the human P2Y2 receptor in order to establish 1321N1 cell lines expressing this receptor, we detected a gene polymorphism characterized by an arginine 334 to cysteine 334 transition. 2. The frequency distribution of the polymorphism was studied in a European population. We observed that 66% of the tested persons are homozygotes R/R, 29% are heterozygotes R/C and 5% are homozygotes C/C. The frequency of the R allele was 0.8 versus 0.2 for the C allele. 3. We stably expressed each form of the human P2Y2 receptor into 1321N1 cells and isolated clones by limiting dilution. The effects of nucleotides and antagonists on inositol trisphosphate accumulation and cyclic AMP formation were compared between the two cell lines. 4. The time-courses of inositol trisphosphate accumulation as well as concentration-response curves characterizing the effects of UTP, ATP, AP4A and ATP gamma S were mostly similar, except for slight kinetic differences (slower time-course with the 334C form). 5. The sensitivity to pertussis toxin of inositol trisphosphates accumulation was critically dependent on the agonist concentration and stimulation duration, suggesting the involvement of a Gi.0 protein during the early stimulation by low nucleotide concentrations. No inhibition of cyclic AMP accumulation could be detected. These properties were observed with both polymorphic receptors.

Adenylyl Cyclases↗

PubMed1999

Functional dissection of CCR5 coreceptor function through the use of CD4-independent simian immunodeficiency virus strains.

With rare exceptions, all simian immunodeficiency virus (SIV) strains can use CCR5 as a coreceptor along with CD4 for viral infection. In addition, many SIV strains are capable of using CCR5 as a primary receptor to infect CD4-negative cells such as rhesus brain capillary endothelial cells. By using coupled fluorescence-activated cell sorter (FACS) and infection assays, we found that even very low levels of CCR5 expression could support CD4-independent virus infection. CD4-independent viruses represent valuable tools for finely dissecting interactions between Env and CCR5 which may otherwise be masked due to the stabilization of these contacts by Env-CD4 binding. Based on the ability of SIV Env to bind to and mediate infection of cells expressing CCR5 chimeras and mutants, we identified the N terminus of CCR5 as a critical domain for direct Env binding and for supporting CD4-independent virus infection. However, the activity of N-terminal domain CCR5 mutants could be rescued by the presence of CD4, indicating that other regions of CCR5 are important for post-binding events that lead to viral entry. Rhesus CCR5 supported CD4-independent infection and direct Env binding more efficiently than did human CCR5 due to a single amino acid difference in the N terminus. Interestingly, uncleaved, oligomeric SIV Env protein bound to both CD4 and CCR5 less efficiently than did monomeric gp120. Finally, several mutations present in chronically infected monkey populations are shown to decrease the ability of CCR5 to serve as a primary viral receptor for the SIV isolates examined.

Amino Acid Sequence↗

PubMed1999

Mapping of the CCXCR1, CX3CR1, CCBP2 and CCR9 genes to the CCR cluster within the 3p21.3 region of the human genome.

Human CC-chemokine receptor genes are known to be clustered. The detailed structure of this cluster was established by radiation hybrid mapping, and organization of BAC contigs by fluorescence hybridization on combed genomic DNA. A main cluster of six genes (CCR1, CCR3, CCRL2, CCR5, CCR2 and CCXCR1), covered by four BACs, was mapped to the 3p21.3 region of the human genome. Five other genes (CCR9, CCBP2, CX3CR1, CCR8 and CCR4) were found to be spread over a relatively large region between this main cluster and the 3p telomere.

CX3C Chemokine Receptor 1↗

PubMed1999

Physical and chemical properties of molecular compounds of lactose.

The physical and chemical properties of the molecular compounds of lactose 5 alpha-/3 beta- and 3 alpha-/2 beta-lactose were studied. The melting point and the heat of combustion were determined. The specific optical rotation of aqueous and organic solutions of these compounds was measured and was in agreement with their stoichiometric formula. Weak differences were observed in the chromatographic mobility of the lactose molecular compounds provided that nonaqueous solvents were used. The analysis by infrared spectroscopy showed that these compounds were due to association of alpha-lactose and beta-lactose crystals by a specific lattice of hydrogen bonding. The latter could be destroyed under controlled water vapor uptake. These physical and chemical properties led us to hypothesize on the means of association of these molecular compounds by comparison with the known structures of the other crystalline lactose forms.

Calorimetry, Differential Scanning↗

PubMed1998

The inhibitory effect of RANTES on the infection of primary macrophages by R5 human immunodeficiency virus type-1 depends on the macrophage activation state.

We investigated whether culture conditions could affect the RANTES antiviral effect on human immunodeficiency virus type 1 (HIV-1) infection of primary macrophages. Monocyte-derived macrophages (MDM) were obtained either as (1) the adherent cells of 5-day cultures of blood mononuclear cells (PBMC), followed by 2 days without nonadherent PBMC or added cytokines (MDM-5d), or (2) as the adherent cells recovered from 1-h incubation of PBMC, which were cultured for 7 days with macrophage colony-stimulating factor (M-CSF; MDM-MCSF). Infection of MDM-5d from different donors with HIV-1 R5 strains was reproducibly inhibited by RANTES (IC50 < or = 10 nM), but infection of MDM-MCSF was not inhibited by > or = 100 nM RANTES, even when added at initiation of cultures, although it was still inhibited by a CD4 antibody. RANTES had no antiviral effect when MDM-5d were treated with physiological concentrations of M-CSF or GM-CSF before infection. CCR5 and CXCR4 expression as well as that of other cell surface molecules, including adhesion molecules, was not affected by the cytokines. MDM-MCSF from delta 32CCR5 homozygous individuals did not render them permissive to HIV-1, suggesting that it is unlikely that the virus uses another coreceptor. RANTES binding to MDM was chondroitin sulfate, but not heparan sulfate, dependent, and RANTES bound more efficiently to MDM-5d than to MDM-MCSF. Chondroitin sulfate removal partially offset the RANTES antiviral effect for MDM-5d. Thus RANTES anti-HIV-1 activity for primary macrophages depends on culture conditions and their consequent activation status, which may lead to differences in proteoglycan surface expression. These data may be relevant for the development of chemokine-based therapy for HIV-1 infection.

Cell Adhesion↗

PubMed1998

Differential patterns of cell cycle regulatory proteins expression in transgenic models of thyroid tumours.

Cell cycle proteins regulate the transitions from G1 to S and G2 to M phases. In higher eukaryotes, their function is controlled by intracellular cascades regulated by extracellular growth factors. We have studied in previously described transgenic mouse models for thyroid proliferative diseases the expression of the key proteins regulating the cell cycle by Western blotting and immunohistochemistry, and have correlated the observations with the known actions of the transgenes on the signal transduction cascades. In the adenosine A2a receptor model, the cyclic AMP pathway, upstream of the Rb family cell division block, is constitutively activated. In the model expressing HPV 16 E7 protein, the Rb-like proteins are inhibited. Cyclin-dependent kinases cdk4, cdk2 and cdc2, and the associated cyclins D, E and A have been studied. Cyclin D3 appears as the major cyclin D subtype expressed in mouse thyroid epithelial cells in normal and transgenic mice. In the adenosine A2aR model, all cell cycle proteins tested were accumulated. In the E7 model, all cell cycle proteins except for D-type cyclins and cdk4 were also accumulated. A similar pattern was observed in thyroids coexpressing both transgenes, suggesting a dominant effect of E7 over the consequences of the cAMP cascade activation. The cyclin-dependent kinase inhibitors p21cip1/waf1 and p27kip1 were not downregulated in these proliferating thyroids which suggest other roles than the inhibition of the cell cycle progression.

Animals↗

PubMed1998

Synthetic full-length and truncated RANTES inhibit HIV-1 infection of primary macrophages.

OBJECTIVE: To determine the effect of beta-chemokines on HIV-1 infection of primary macrophages, and to search for chemokine derivatives devoid of biological effects but efficient at protecting CD4+ T lymphocytes and macrophages against HIV-1. DESIGN: Use of chemically synthesized molecules devoid of biological contaminants and monocyte-derived macrophages from healthy donors. METHODS: Full-length RANTES was chemically synthesized together with three derivatives, truncated of seven, eight and nine amino acids at the amino-terminus ([8-68]RANTES, [9-68]RANTES and [10-68]RANTES), which were tested for their biological activity and antiviral effects. RESULTS: Whereas full-length and truncated RANTES derivatives bound to beta-chemokine receptor CCR-5 with the same affinity as recombinant RANTES, the truncated forms were not chemotactic and acted as CCR-5 antagonists in this respect, although a partial agonist effect was noted on cell metabolism. Full-length RANTES and [8-68]RANTES protected T lymphocytes and macrophages from infection by HIV-1, although 10-fold higher concentrations of the truncated analogues were necessary to achieve the same effect as full-length RANTES. With regard to the effect of RANTES on HIV-1 infection of primary macrophages, our results contrast with most previously reported data. CONCLUSION: These data indicate that through binding to CCR-5, truncated RANTES derivatives that are devoid of detectable biological effects may represent candidates as drugs to protect both lymphocytes and macrophages from HIV- 1.

Animals↗

PubMed1998

Distribution of a glucocorticoid-induced orphan receptor (JP05) mRNA in the central nervous system of the mouse.

JP05 (originally referred to as glucocorticoid-induced receptor gene or cDNA clone 4.2) designates a gene originally isolated from murine thymoma WEHI-7TG cells after being treated with glucocorticoids and forskolin. This gene is also induced by dexamethasone (a potent glucocorticoid receptor agonist) in isolated normal murine thymocytes. The predicted amino acid sequence was found to share significant similarity to the family of G-protein-coupled receptors, in particular to the tachykinin receptors NK-1, NK-2 and NK-3, with which it has an overall identity of 32%, 31% and 33%, respectively. The results of the present in situ hybridization analysis reveal that JP05 mRNA containing cells are extensively distributed throughout the rostrocaudal extension of the brain and spinal cord. However, the vast majority of the areas with high to moderate levels of JP05 mRNA were localized in the forebrain, primarily within limbic system structures, the dorsal and ventral striatum and in some hypothalamic nuclei. These results are discussed in relation to the central nervous system distribution of glucocorticoid receptor-containing cells and to the tachykinin system.

Amygdala↗

PubMed1998

Genomic organization and promoter characterization of human CXCR4 gene.

CXCR4 is the receptor for the CXC chemokine SDF1 that has essential functions on embryo organogenesis, immunological functions and T lymphocyte trafficking. Recently, CXCR4 has drawn unexpected attention as it was recently identified as a co-factor required for entry of lymphotropic HIV isolates in CD4+ T lymphocytes. CXCR4 is the only SDF1 receptor identified so far. This suggests that CXCR4 expression is critical for the biological effects of SDF1. To investigate the mechanisms controlling both the constitutive and induced expression of CXCR4 receptors we have isolated and characterized the promoter region and determined the genomic structure of the human gene. The CXCR4 gene contains two exons separated by an intronic sequence. A 2.6 kb 5'-flanking region located upstream the CXCR4 open reading frame contains a TATA box and the transcription start site characteristic of a functional promoter. This region also contains putative consensus binding sequences for different transcription factors, some of them associated with the hemopoiesis and lymphocyte development.

Base Sequence↗