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C Gautier

Publications and source records attributed to C Gautier.

At least 19 recordsLinked to original sources
PubMed2006

Comparisons between LIBS and ICP/OES.

In the framework of the development of new techniques, the ability of laser-induced breakdown spectroscopy (LIBS) to analyse remotely complex aqueous solutions was investigated. The jet configuration with a collimated gas stream was chosen because it appeared to be the most promising method for the LIBS probe, particularly in terms of sensitivity and repeatability. For emission collection, the echelle spectrometer offers a simultaneously recorded wavelength range from the UV to the near IR and is interesting for multielemental analysis for LIBS and also for inductively coupled plasma (ICP) optical emission spectroscopy (OES). The importance of parameters influencing the quantitative results of LIBS such as multispecies analysis, sheath gas, use of an internal standard and temporal parameters for analysis is described. LIBS quantitative data have been directly compared with results from the more standard ICP/OES technique.

Journal Article↗
PubMed2006

[Three-dimensional echography: cardiovascular applications].

Real-time three-dimensional echocardiography is currently used in a standard echocardiographic examination. Volume-rendered images better identify and locate anatomic structures and improve our comprehensive approach to various heart diseases. The assessment of mitral valve disease and congenital cardiopathies and the measurement of left ventricular mass, volume, and ejection fraction are the three main applications of three-dimensional echocardiography. Three-dimensional vascular imaging is an emerging and promising application of three-dimensional echography. The near future of three-dimensional echography requires the integration of all modalities of conventional echography in three dimensional probes, a higher image resolution compared to the current situation, as well as the development of real-time three-dimensional probes dedicated to transesophageal cardiac or vascular examination.

Adult↗
PubMed2005

[The role of carotid and transcranial Doppler sonography in the management of ischemic stroke].

Carotid stenosis is a common cause of ischemic stroke. The management of patients with a carotid lesion is mainly based on the degree of stenosis. Ultrasonography is a reliable and accurate method of quantification of the stenosis. The sonographic quantification is based on both velocity and morphological criteria. B mode, color or power Doppler as well as spectral Doppler are used for this purpose. The actual velocity criteria for a 70% stenosis (NASCET definition) are as follows: maximal systolic velocity above 230 cm.s-1, telediastolic velocity above 100 cm.s-1, carotid ratio above 4. The morphological quantification of the stenosis relies on Doppler imaging and B-mode coupling. With ultrasound, the residual area can be measured using a short axis plane, and the diameter reduction using a longitudinal plane. The different parameters provide complementary information that must be in agreement with one another. There is a growing interest in plaque characterization. Undoubtedly plaque structure and surface appearance also play a role in the individual risk of stroke. Thus, B-mode plaque analysis must be an integral part of the ultrasonographic examination. Transcranial Doppler is a complementary investigation that can be used to evaluate the hemodynamic consequences of the stenosis and to look for intracranial lesions. Optimal sonographic examination currently allows comprehensive evaluation of a carotid lesion.

Aortic Dissection↗
PubMed2003

Impairment of endothelial function in patients with spontaneous cervical artery dissection: evidence for a general arterial wall disease.

BACKGROUND AND PURPOSE: Cervical artery dissection (CAD) accounts for 10-20% of ischemic strokes in young adults. Although trauma and preexisting disorders of the arterial wall are the main predisposing factors, most CADs are considered 'spontaneous'. We hypothesized that CAD could originate in systemic vascular disease bound to the intima-media interface without clinical signs. If this hypothesis is true, endothelium-dependent vasodilation would be impaired in response to a physiological stimulus such as an increase in blood flow. METHODS: Flow-mediated arterial dilation was studied in 65 consecutive patients with spontaneous CAD: 26 with carotid artery dissection (ICAD), and 39 with vertebral artery dissection (VAD). CAD patients with vascular risk factors, trivial or obvious cervical trauma, or connective tissue disease were excluded. Twenty-three patients with ischemic stroke of unknown cause were included as controls. Using high-resolution ultrasonography, brachial artery diameter was measured at rest, during post-ischemic hyperemia (flow-mediated endothelium-dependent dilation), and after sublingual glyceryl trinitrate spray (endothelium-independent dilation). RESULTS: The mean +/- SD values of the flow-mediated vasodilation index were 5.7 +/- 6.2% in ICAD, 5.0 +/- 9.3% in VAD and 13.2 +/- 6.5% in controls (p < 0.0005), without any difference between ICAD and VAD. Endothelium-independent dilation mean values were 21.5 +/- 9.5% in ICAD, 25.1 +/- 12.5% in VAD, and 20.8 +/- 8.4% in controls, without a significant difference between groups (p = 0.49). CONCLUSIONS: These results give evidence of impaired endothelium-dependent vasodilation in CAD patients that is not the result of stroke, and suggest that an underlying abnormality of the arterial wall layers may predispose to CAD.

Adult↗
PubMed2003

Angioplasty and stenting for high-grade internal carotid artery stenosis: safety study in 39 selected patients.

BACKGROUND: Carotid angioplasty and stenting (CAS) is sometimes used as an alternative to surgery, despite the lack of evidence for its safety and efficacy. METHOD: Over a 33-month period, 39 consecutive patients with a stenosis >/=70% underwent CAS (4 in a randomized trial and 35 because of contra-indications for surgery). RESULTS: In 5 patients (13%; 95% CI: 3-23), a major complication occurred (3 disabling ischaemic strokes, 1 myocardial infarction, 1 acute interstitial nephropathy). In 7 patients (18%; 95% CI: 6-30), a minor complication occurred (5 transient ischaemic attacks, 1 transient confusional state, 1 non-disabling ischaemic stroke). CONCLUSION: CAS cannot be considered as a routine procedure and should be restricted to high-risk patients unfit for surgery.

Adult↗
PubMed2003

Percutaneous transluminal angioplasty of proximal vertebral artery stenosis: long-term clinical follow-up of 16 consecutive patients.

We report long-term (average 30 months) clinical and radiological follow-up of 16 consecutive patients with uni- or bilateral proximal vertebral artery stenosis who underwent percutaneous transluminal angioplasty (PTA), without stenting, between 1995 and 1998. Assessment was performed by an independent neurologist. All patients but one remained asymptomatic during follow-up; moderate restenosis was observed in four. PTA of the proximal vertebral artery is safe but in the absence of knowledge of the natural history of atherosclerotic vertebral artery stenosis, whether it is beneficial or not remains unproven. The decision as to whether to perform this procedure is individual.

Adult↗
PubMed2003

[Value of sonographic contrast agents in the evaluation of the cerebral arteries].

Stroke is a frequent and severe disorder. Most strokes are ischemic in nature and 20% are due to atherosclerosis of the cerebral arteries. Sonographic examination plays a key role in the diagnosis and management of patients with cerebrovascular disease. However, shortcomings can be encountered in the ultrasound evaluation of cervical and intracranial arteries. Contrast agents are known to improve the signal / noise ratio and they can therefore compensate for these shortcomings in most cases. They have proved to be helpful in unfavorable examinations in daily practice. Moreover, their use increases the accuracy and the potential of the technique especially in the intra-cranial examination, increasing the role of ultrasound techniques.

Carotid Artery Diseases↗
PubMed2002

Modeling comparative mapping using objects and associations.

Spatial information on genome organization is essential for both gene prediction and annotation among species and a better understanding of genomes functioning and evolution. We propose in this article an object-association model to formalize comparative genomic mapping. This model is being implemented in the GeMCore knowledge base, for which some original capabilities are described. GeMCore associated to the GeMME graphical interface for molecular evolution was used to spatially characterize the minor shift phenomenon between human and mouse.

Animals↗
PubMed2001

Amphetamine-induced dopamine release in human ventral striatum correlates with euphoria.

BACKGROUND: Studies in experimental animals have implicated the mesolimbic dopaminergic projections into the ventral striatum in the neural processes underlying behavioral reinforcement and motivated behavior; however, understanding the relationship between subjective emotional experience and ventral striatal dopamine (DA) release has awaited human studies. Using positron emission tomography (PET), we correlated the change in endogenous dopamine concentrations following dextroamphetamine (AMPH) administration with the associated hedonic response in human subjects and compared the strength of this correlation across striatal subregions. METHODS: We obtained PET measures of [(11)C]raclopride specific binding to DA D2/D3 receptors before and after AMPH injection (0.3 mg/kg IV) in seven healthy subjects. The change in [(11)C]raclopride binding potential (DeltaBP) induced by AMPH pretreatment and the correlation between DeltaBP and the euphoric response to AMPH were compared between the anteroventral striatum (AVS; comprised of accumbens area, ventromedial caudate, and anteroventral putamen) and the dorsal caudate (DCA) using an MRI-based region of interest analysis of the PET data. RESULTS: The mean DeltaBP was greater in the AVS than in the DCA (p <.05). The AMPH-induced changes in euphoria analog scale scores correlated inversely with DeltaBP in the AVS (r = -.95; p <.001), but not in the DCA (r =.30, ns). Post hoc assessments showed that changes in tension-anxiety ratings correlated positively with DeltaBP in the AVS (r =.80; p [uncorrected] <.05) and that similar relationships may exist between DeltaBP and emotion ratings in the ventral putamen (as were found in the AVS). CONCLUSIONS: The preferential sensitivity of the ventral striatum to the DA releasing effects of AMPH previously demonstrated in experimental animals extends to humans. The magnitude of ventral striatal DA release correlates positively with the hedonic response to AMPH.

Adult↗
PubMed2001

Multiplicative versus additive selection in relation to genome evolution: a simulation study.

The evolution of molecular quantitative traits, such as codon usage bias or base frequencies, can be explained as the result of mutational biases alone, or as the result of mutation and selection. Whereas mutation models can be investigated easily, realistic modelling of selection-directed genome evolution is analytically intractable, and numerical calculations require substantial computer resources. We investigated the evolution of optimal codon frequency under additive and multiplicative effects of selected linked codons. We show that additive selective effects of many linked sites cannot be effective in genomes when the number of selected sites is greater than the effective population size, a realistic assumption according to current molecular data. We then discuss the implications of these results for isochore evolution in vertebrates.

Codon↗
PubMed2001

[Post-irradiation axillo-subclavian arteriopathy: surgical revascularization].

Post-irradiation axillo-subclavian arteriopathy can develop 6 months to 20 years after radiotherapy. Incidence estimated from duplex scan screening is about 30%, half of the cases having no hemodynamic significance. In our experience, asymptomatic lesions are the most common. Nevertheless, we have observed since 1978, 38 symptomatic patients including 23 with either acute ischemia (8 patients), or chronic ischemia (15 patients) requiring revascularization. We used an endovascular approach in 8 and open surgery in 15. A bypass graft was performed in 13 patients, using a vein (8 patients) rather than a prosthesis (5 patients), implanted in healthy territory, proximally or in the common carotid (11 patients) or the proximal subclavian (2 patients), and distally in the axillary artery (5 patients) or the brachial artery (8 patients). One venous bypass became occluded postoperatively. The other bypasses remained patent during follow-up of over 10 years. There of the five prosthetic bypassess gradually failed without recurrence of critical ischemia. Other revascularization procedures included endarterectomy and thrombectomy. In the long term, functional prognosis mainly depended on the frequently associated involvement of the plexus in the post-irradiation changes, which, together with the revascularization procedure, also required neurolysis in 11 patients, two omental covers and a free musculocutaneous transfer in 9 patients.

Adult↗
PubMed2001

[Techniques for evaluating the degree of carotid artery stenosis].

Conventional angiography is considered to be gold standard for evaluating the degree of carotid artery stenosis. However, this technique carries a risk of complications. Thus, noninvasive techniques have been developed to avoid conventional angiography. Among these techniques, duplex sonography certainly constitutes the most attractive method, providing both morphological and hemodynamic data by combining different acquisition modalities. Contrast-enhanced MR angiography (MRA) is a recent development providing information on the intracranial and cervical vascularization in a short acquisition time. Previous studies have showed the reliability of this technique to detect severe carotid stenosis. Helicoidal CT is a third noninvasive method providing a reliable evaluation of carotid artery stenosis by analyzing both the axial CT images and the 3D reconstruction. However, CT angiography requires a radiation does and injection of an iodinated contrast agent. Moreover, the surrounding venous and bone structures may obscure evaluation of the arterial lumen.

Carotid Stenosis↗
PubMed2000

Identification of essential amino acids in the bacterial alpha -mannosyltransferase aceA.

The alpha-mannosyltransferase AceA from Acetobacter xylinum belongs to the CaZY family 4 of retaining glycosyltransferases. We have identified a series of either highly conserved or invariant residues that are found in all family 4 enzymes as well as other retaining glycosyltransferases. These residues included Glu-287 and Glu-295, which comprise an EX(7)E motif and have been proposed to be involved in catalysis. Alanine replacements of each conserved residue were constructed by site-directed mutagenesis. The mannosyltransferase activity of each mutant was examined by both an in vitro transferase assay using recombinant mutant AceA expressed in Escherichia coli and by an in vivo rescue assay by expressing the mutant AceA in a Xanthomonas campestris gumH(-) strain. We found that only mutants K211A and E287A lost all detectable activity both in vitro and in vivo, whereas E295A retained residual activity in the more sensitive in vivo assay. H127A and S162A each retained reduced but significant activities both in vitro and in vivo. Secondary structure predictions of AceA and subsequent comparison with the crystal structures of the T4 beta-glucosyltransferase and MurG suggest that AceA Lys-211 and Glu-295 are involved in nucleotide sugar donor binding, leaving Glu-287 of the EX(7)E as a potential catalytic residue.

Acetobacter↗
PubMed2000

Familial invasive breast cancers: worse outcome related to BRCA1 mutations.

PURPOSE: Although all studies confirm that BRCA1 tumors are highly proliferative and poorly differentiated, their outcomes remain controversial. We propose to examine, through a cohort study, the pathologic characteristics, overall survival, local recurrence, and metastasis-free intervals of 40 patients with BRCA1 breast cancer. PATIENTS AND METHODS: A cohort of 183 patients with invasive breast cancer, treated at the Institut Curie and presenting with a familial history of breast and/or ovarian cancer, were tested for BRCA1 germ-line mutation. Tumor characteristics and clinical events were extracted from our prospectively registered database. RESULTS: Forty BRCA1 mutations were found among the 183 patients (22%). Median follow-up was 58 months. BRCA1 tumors were larger in size (P =.03), had a higher rate of grade 3 histoprognostic factors (P =.002), and had a higher frequency of negative estrogen (P =.003) and progesterone receptors (P =.002) compared with non-BRCA1 tumors. Overall survival was poorer for carriers than for noncarriers (5-year rate, 80% v 91%, P =.002). Because a long time interval between cancer diagnosis and genetic counseling artificially increases survival time due to unrecorded deaths, the analysis was limited to the 110 patients whose diagnosis-to-counseling interval was less than 36 months (19 BRCA1 patients and 91 non-BRCA1 patients). The differences between the BRCA1 and non-BRCA1 groups regarding overall survival and metastasis-free interval were dramatically increased (49% v 85% and 18% v 84%, respectively). Multivariate analysis showed that BRCA1 mutation was an independent prognostic factor. CONCLUSION: Our results strongly support that among patients with familial breast cancer, those who have a BRCA1 mutation have a worse outcome than those who do not.

Adult↗
PubMed2000

An unusual carbohydrate binding site revealed by the structures of two Maackia amurensis lectins complexed with sialic acid-containing oligosaccharides.

Seeds from the legume tree Maackia amurensis contain two lectins that can agglutinate different blood cell types. Their specificity toward sialylated oligosaccharides is unique among legume lectins; the leukoagglutinin preferentially binds to sialyllactosamine (alphaNeuAc(2-3)betaGal(1-4)betaGlcNAc), whereas the hemagglutinin displays higher affinity for a disialylated tetrasaccharide (alphaNeuAc(2-3)betaGal(1-3)[alphaNeuAc(2-6)]alphaG alNAc). The three-dimensional structure of the complex between M. amurensis leukoagglutinin and sialyllactose has been determined at 2.75-A resolution using x-ray crystallography. The carbohydrate binding site consists of a deep cleft that accommodates the three carbohydrate residues of the sialyllactose. The central galactose sits in the primary binding site in an orientation that has not been observed previously in other legume lectins. The carboxyl group of sialic acid establishes a salt bridge with a lysine side chain. The glucose residue is very efficiently docked between two tyrosine aromatic rings. The complex between M. amurensis hemagglutinin and a disialylated tetrasaccharide could be modeled from the leukoagglutinin/sialyllactose crystal structure. The substitution of one tyrosine by an alanine residue is responsible for the difference in fine specificity between the two isolectins. Comparison with other legume lectins indicates that oligosaccharide specificity within this family is achieved by the recycling of structural loops in different combinations.

Amino Acid Sequence↗
PubMed2000

Characterization of the binding of alpha-L-Fuc (1-->2)-beta-D-Gal (1-->), a xyloglucan signal, in blackberry protoplasts.

Previous work showed that the fucose-->galactose moiety of the xyloglucan nonasaccharide XXFG is responsable for its biological activity. We used this side chain of XXFG (alpha-L-Fuc (1-->2)-beta-D-Gal (1-->)) in ligand-binding experiments to demonstrate its role as a signal molecule in plant cells. Proteins solubilized from plasma membrane enriched fractions isolated from Rubus fruticosus protoplasts were tested for their ability to bind the side chain of XXFG, using a digoxigenin- or biotin-conjugated neoglycoprotein specific for 2'-fucosyl-lactose in blots and k-ELISA tests. A putative receptor for the signaling sugar was identified, and the ligand specificity is reported. The role of structural elements important for biological activities was investigated using compounds structurally related to xyloglucan, and a variety of phytohormones such as 2,4-D.

Journal Article↗
PubMed2000

Compositional bias in DNA.

Experimental approaches, as well as computer analysis on genomic sequences, have revealed a large variability in base composition between regions in the same genome or between genomes of different species. In most cases, however, the biological causes of these compositional biases remain unknown. The recent large increase in the availability of completely sequenced genomes can give new insight into evolution processes involved in these compositional biases.

Animals↗