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Biomedical subjects

C Moreau

Publications and source records attributed to C Moreau.

At least 73 records · Page 4Linked to original sources
PubMed1994

Functional analysis of the tobacco Tnt1 retrotransposon.

Retroelements represent by far the largest and most widespread class of mobile genetic elements. Representative of several classes of retrotransposons have been characterized in a broad range of plant species, but only a few of them have been shown to be active. Among these, the tobacco Tnt1 retrotransposon has been isolated after insertion mutagenesis and is one of the very few to be transcriptionally active. Tnt1 expression is strongly regulated in a tissue-specific and developmental manner. Moreover, Tnt1 expression is induced by a range of biotic or abiotic elicitors, which all have in common the ability to induce the plant defense response. Regulatory sequences involved in this elicitor-mediated induction have been located in the LTR U3 region. The link between Tnt1 activation and the plant defense response might represent an example of the involvement of transposable elements in genome restructurations needed in response to environmental fluctuations such as pathogen attacks.

Base Sequence↗
PubMed1994

[A new titanium-carbon finger joint implant. Apropos of 15 initial cases].

Arthroplasty of the MP and PIP joint remains a therapeutic challenge for the hand surgeon. The poor results of the currently available implants are due to their mechanical conception (non strained) or their material (silicone causing instability, ruptures and silicone synovitis). The authors present the preliminary results of a new digital articular implant (IAD). It is a strained implant with a rigid hinge allowing 105 degrees of range of movement (0 degree to 105 degrees). Three sizes are available and very soon four. The intramedullary stems are in titanium alloy (TA6V) and the gliding surfaces in pyrolytic carbon. This association allows solidity, endurance, excellent gliding and no wear debris. 15 implants were evaluated (13 PIP and 2 MP joints) with a follow-up from 4 to 1 year. A painless range of motion were restored in 11 cases and 4 articulations were only lightly painful during motion requiring strength and at the end of the movement. The gain of the range of movement was 50 degrees always in a useful sector. The grasp was 60% better in post than in pre operative conditions. No infection was found. It is only the beginning of this implant but the indications seem to be good for all the articular destructions of the digital joints what ever was the aetiology (traumatic, infection or rheumatoid arthritis).

Adult↗
PubMed1994

Regulation of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in human vascular smooth muscle cells.

Vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin are inducible proteins involved in cell-cell adhesion. Immunohistochemical studies have indicated that human atherosclerotic plaques contain smooth muscle cells (SMCs) that express ICAM-1 and VCAM-1. Recently, we demonstrated that SMCs in culture express a functionally active cytokine-inducible ICAM-1. SMCs and mononuclear cells participate in the local accumulation of cytokines and related growth factors in atherosclerotic lesions. Therefore, we determined the effects of different cytokines and growth factors on mRNA content and cell surface expression of VCAM-1, ICAM-1, and E-selectin in cultured human aortic SMCs by Northern blotting, quantitative polymerase chain reaction amplification, and immunofluorescence flow cytometry. Under basal conditions of cultivation, both VCAM-1 mRNA and membrane expression of VCAM-1 were low and were induced very little by interleukin-1 beta (100 U/mL). Platelet-derived growth factor or transforming growth factor-beta decreased VCAM-1 mRNA basal expression. Treatment of SMCs with tumor necrosis factor-alpha (TNF-alpha) led to an increase in both VCAM-1 mRNA and cell surface expression for VCAM-1 in a dose- and time-dependent manner. Interferon-gamma induced a weak increase in VCAM-1 mRNA expression, with no synergistic effect on the stimulation by TNF-alpha. Various differences were noted between the expression of ICAM-1 and VCAM-1 genes, because interleukin-1 beta induced substantial amounts of ICAM-1 but not VCAM-1. The addition of interferon-gamma delays the time at which peak expression of ICAM-1 in response to TNF-alpha stimulation occurs. Under our conditions, we did not detect any expression of E-selectin by SMCs. These results suggest that cytokines regulate VCAM-1 and ICAM-1 expression on arterial SMCs and could play an important role in the pathophysiology of inflammatory and immune processes in atherosclerosis.

Base Sequence↗
PubMed1993

Interaction of calmodulin with a putative calmodulin-binding domain of inositol 1,4,5-triphosphate 3-kinase. Effects of synthetic peptides and site-directed mutagenesis of Trp165.

Recombinant rat brain inositol 1,4,5-triphosphate [Ins(1,4,5)P3] 3-kinase was expressed in Escherichia coli as a beta-galactosidase fusion product. It could be adsorbed onto calmodulin-Sepharose and eluted in Ca(2+)-free medium as a 48-kDa protein. Purification could be achieved in a single step. Molecular evidence for a calmodulin-binding domain on Ins(1,4,5)P3 3-kinase can be shown by the following approaches. (a) Inhibition of Ca2+/calmodulin stimulation by a synthetic peptide based on a candidate calmodulin-binding domain. The inhibition was mimicked by a well-characterized peptide derived from the sequence of smooth muscle myosin light-chain kinase calmodulin-binding site. (b) The construction of two mutants by site-directed mutagenesis of Trp165 to Gly or Arg. Both mutants displayed kinase activity but were no longer Ca2+/calmodulin sensitive, supporting, therefore, the role of Trp165 in calmodulin binding.

Amino Acid Sequence↗
PubMed1993

Quantitative analysis of polymerase chain reaction products using biotinylated dUTP incorporation.

A method for relative quantitation of specific mRNA species by polymerase chain reaction (PCR) has been developed by using the incorporation of biotinylated dUTP. Transferred biotinylated PCR products gave a sensitive colorimetric signal which could be quantitated by video analysis. In the exponential phase of amplification, the linearity and reproducibility of reverse transcription and PCR demonstrated the same efficiency of cDNA synthesis and PCR for the two target genes, ICAM-1 and beta-actin, and allowed the normalization of ICAM-1 expression. These results suggested that in the exponential phase of amplification a relative quantitation of mRNA could be determined. We used this approach to analyze the different effects of TNF-alpha, IL-1 beta, and purified porcine platelet-derived growth factor stimulations on ICAM-1 expression in smooth muscle cells.

Base Sequence↗
PubMed1993

Effect of low density lipoprotein on monocyte adhesiveness to endothelial cells in vitro.

Adhesion of monocytes to the endothelium is an early event in the development of atherosclerosis. The possibility that low density lipoproteins enhance this process by activating monocytes was investigated using an in vitro adhesion test on endothelial cell monolayer cultures. Preincubation of monocytes with low density lipoprotein (LDL) (100 micrograms LDL protein/l x 10(6) cells/ml) for 15 min induced a 70% increase in adhesion to endothelial cells with a maximal effect at 100 micrograms LDL protein/ml and a short latency of effect (2 min). Anti-LDL receptor antibody, which inhibited LDL binding, blocked this activation. The LDL effect appeared to depend on receptor binding of LDL rather than on receptor-mediated endocytosis, since preincubation of monocytes with LDL at either 4 degrees C or 37 degrees C resulted in the same stimulation of adhesion. A cytofluorimetric study using integrin monoclonal antibodies (MAbs) against CD18 and CD11b did not reveal any increase in expression of the integrins on the surface of LDL-activated monocytes. However, a 30-min preincubation of monocytes with anti-CD18 abolished the LDL-activated adhesion. These results indicate that LDL induces a rapid activation of monocyte adhesiveness to endothelial cells. This effect appears to be mediated by interaction of LDL with its receptor rather than LDL-receptor complex internalization or integrin membrane mobilization from intracellular pools. The integrin system nevertheless appears to be involved.

Antibodies, Monoclonal↗
PubMed1993

Response of genetically obese Zucker rats to ciprofibrate, a hypolipidemic agent, with peroxisome proliferation activity as compared to Zucker lean and Sprague-Dawley rats.

Genetically obese Zucker (fa/fa) rats were used as an experimental model to study the effects of hypolipidemic agents on peroxisome proliferation; comparison was made with Zucker lean phenotype (Fa/-) and Sprague-Dawley strain/phenotype. The pharmacokinetics of a single administration of ciprofibrate (1 or 3 mg/kg), appeared to be similar in all strains/phenotypes. After a 2-week oral administration at the same dosages, there were dosage-related increases in hepatocellular peroxisomal yield and in the hepatic enzymes' cyanide-insensitive acyl-CoA oxidase and catalase. The peroxisomal yield was less increased in Zucker than in Sprague-Dawley rats, while the enzyme activities were similarly increased. Although the absolute specific activity of microsomal omega-lauryl hydroxylase (cytochrome P4504A1) was lower in Zucker rats, it was increased more in this strain than in Sprague-Dawley rats in response to drug exposure. The hypolipidemic effect (cholesterol and triglyceride reduction) was more pronounced in Zucker obese rats. Based on biochemical and morphological results, no major differences between strains/phenotypes in terms of peroxisome proliferation were observed following a 2-week administration of ciprofibrate.

Animals↗
PubMed1993

Monocyte adherence to endothelial cells in patients with atherosclerosis: relationships with risk factors.

Monocyte adhesion to endothelium appearing determinant in atherosclerosis, the possibility that circulating monocytes have an increase of their adherence on endothelial cells were investigated in patients with atherosclerosis. The adherence of circulating monocytes on endothelial cell monolayers was determined in 26 patients with atherosclerosis (age 59 +/- 4), and 25 healthy individuals (age 55 +/- 4). No difference of monocyte adherence was observed between the two groups (18.8 +/- 13.8% vs 19.2 +/- 13.4%), or following atherosclerosis severity. However, monocyte adherence appeared positively correlated to smoking habits (r = 0.34, P < 0.02) and fibrinogen level (r = 0.31, P < 0.03), and negatively to the degree of plasmatic LDL oxidation (r = -0.28, P < 0.05). These results suggest that the adherence of monocytes to endothelial cells is not increased in atherosclerosis, but enhanced by risk factors. A weak plasmatic LDL oxidation could inhibit monocyte adhesion.

Arteriosclerosis↗
PubMed1993

Tumor necrosis factor-alpha stimulates ICAM-1 expression in human vascular smooth muscle cells.

Human atherosclerotic plaques contain numerous smooth muscle cells (SMCs) that express intercellular adhesion molecule-1 (ICAM-1). Expression of ICAM-1 in different cells is known to be regulated by tumor necrosis factor-alpha (TNF-alpha), which has recently been found to be present in the intimal thickening of human arteries. Therefore, we studied the effect of TNF-alpha on ICAM-1 mRNA content and surface expression in cultured human aortic SMCs by using the methods of Northern blotting and immunofluorescence flow cytometry. Under basal conditions of cultivation, ICAM-1 mRNA was not revealed in SMCs. However, treatment of the cells with recombinant human TNF-alpha induced substantial levels of ICAM-1 mRNA. The content of ICAM-1 on the surface of SMCs also increased in a dose- and time-dependent manner after incubation with TNF-alpha. Twenty-four hours of treatment with 10 ng/mL TNF-alpha led to an approximately 10-fold increase in ICAM-1 surface expression in the SMCs. Under the same conditions, pretreatment of SMCs with TNF-alpha resulted in a twofold increase of their adhesiveness for monocytes. In the presence of anti-ICAM-1 monoclonal antibody 10F3, monocyte adhesion to TNF-alpha-pretreated SMCs was significantly inhibited, suggesting that the observed monocyte-SMC interaction involved the ICAM-1 expressed on SMC surfaces as a result of TNF-alpha stimulation. These results led us to propose that TNF-alpha may act a regulator of functional ICAM-1 expression on the SMC surface and thus can increase the possibility of interactions between mononuclear cells and SMCs in atherosclerotic plaques.

Antibodies, Monoclonal↗
PubMed1992

Purification of bovine brain inositol-1,4,5-trisphosphate 5-phosphatase.

In bovine brain, two soluble inositol-1,4,5-trisphosphate (InsP3) 5-phosphatases, which catalyse the dephosphorylation of InsP3 to inositol 1,4-bisphosphate, have been separated by DEAE-Sephacel. Type I, i.e. the first eluted enzyme, is the main soluble form and is reminiscent of the membrane-bound enzyme by multiple criteria. Type I was purified to apparent homogeneity by a method involving chromatography on DEAE-Sephacel, Blue-Sepharose, Sephacryl S-200, phosphocellulose, and C18 HPLC. A single protein band of 42-43 kDa was identified by SDS/PAGE, corresponding to the peak of maximal activity. InsP3 5-phosphatase was purified to apparent homogeneity to a final yield of 45-50 micrograms protein. The minimal estimate value of the Vmax for InsP3 5-phosphatase was in the range 20-35 mumol.min-1.mg protein-1.

Animals↗
PubMed1992

Quinoxaline derivatives: structure-activity relationships and physiological implications of inhibition of N-methyl-D-aspartate and non-N-methyl-D-aspartate receptor-mediated currents and synaptic potentials.

The inhibitory potencies at excitatory amino acid (EAA) receptors of 11 quinoxaline derivatives were evaluated in two-electrode voltage-clamp recordings of Xenopus oocytes injected with rat cortex mRNA. Currents activated by kainate or (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) in Xenopus oocytes were inhibited competitively by all the quinoxaline derivatives, with apparent Ki values ranging from 0.27 to 300 microM against kainate and from 0.25 to 137 microM against AMPA. An excellent correlation was observed between inhibitory potencies of the quinoxaline derivatives against kainate and AMPA currents, in support of the contention that in this preparation these two agonists act at a single site. All 11 quinoxaline derivatives also inhibited current activated by the combination of glycine and N-methyl-D-aspartate (NMDA), apparently acting at the glycine site, and did so over a narrower range of apparent Ki values (0.37-8.1 microM). The correlation between the quinoxalines' kainate/AMPA potencies and their glycine/NMDA potencies was relatively weak. Thus, the quinoxaline derivatives were all good antagonists of glycine/NMDA currents and displayed a greater range of potencies against kainate and AMPA. The inhibitory effects of the six quinoxaline derivatives most potent in the Xenopus oocyte experiments were also tested against the excitatory postsynaptic field potential (EPSFP) recorded in the pyramidal cell dendritic field of the CA1 region of hippocampal slices after stimulation of the Schaffer collateral-commissural pathways. In slices superfused with "normal" medium (containing 1 mM Mg2+), in which the EPSFP is mediated primarily by non-NMDA receptors, IC50 values correlated closely with the Ki values against kainate/AMPA obtained in oocyte experiments but were approximately 8-fold higher. Similarly, in slices superfused with nominally Mg(2+)-free medium, in which the EPSFP is amplified due to a relief of the Mg2+ block of NMDA receptors, IC50 values correlated closely with the Ki values against glycine/NMDA obtained in oocyte experiments but were 60-fold higher. This comparison of results from the two experimental systems lends further support to the argument that hippocampal synaptic transmission is mediated postsynaptically by kainate/AMPA-type and NMDA/glycine-type EAA receptors that are pharmacologically indistinguishable from those expressed in mRNA-injected Xenopus oocytes. Furthermore, it suggests that EAA receptors in situ may be nearly saturated by high local concentrations of the endogenous ligands, a condition that would contribute substantially to the apparent non-NMDA receptor selectivity of certain quinoxaline derivatives.

Animals↗