Biomedical subjects

Catherine Vayssettes

Publications and source records attributed to Catherine Vayssettes.

6 recordsLinked to original sources

PubMed2006

Placental perfusion and permeability: simultaneous assessment with dual-echo contrast-enhanced MR imaging in mice.

PURPOSE: To assess placental perfusion and permeability in mice with magnetic resonance (MR) imaging. MATERIALS AND METHODS: This study was conducted according to French law and National Institutes of Health recommendations for animal care. Twenty-two pregnant BALB/c mice were examined at 1.5 T with a single-section dual-echo fast spoiled gradient-echo sequence. Two injection protocols were used: monophasic injection (double the clinical dose of contrast agent) and biphasic injection (quadruple the clinical dose). Signal intensities (SIs) were measured in the maternal left ventricle, placenta, and fetus (n = 16). At these high gadolinium doses, a T2* effect correction was used. SIs were converted to gadolinium concentrations and were analyzed by using a three-compartment model. Quantitative microcirculation parameters were calculated. Results with the monophasic and biphasic protocols were compared, and final arterial concentrations determined with MR imaging were compared with those determined with atomic emission spectrophotometry by using the unpaired Student t test. RESULTS: Perfusion and permeability parameters for monophasic and biphasic injections were similar: Mean placental blood flow was 180 mL/min/100 g, mean permeability surface coefficient from maternal placental to fetal placental compartment was 10.3 x 10(-4) sec(-1) +/- 6.81 (standard deviation), mean permeability surface coefficient from fetal placental to maternal placental compartment was 4.65 x 10(-4) sec(-1) +/- 4.37, and mean fractional volume of the maternal vascular placental compartment was 36.5% +/- 0.9. Placental (146 vs 105 micromol/L, P < .004) and fetal (33.3 vs 19.1 micromol/L, P < .001) gadolinium concentrations were higher with the biphasic than with the monophasic protocol. Arterial gadolinium concentrations at MR imaging did not differ significantly from those at spectrophotometry for the monophasic (P = .254) or biphasic (P = .776) injection protocol. CONCLUSION: Placental perfusion and permeability can be measured in vivo by using high gadolinium doses and a dual-echo MR imaging sequence.

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PubMed2005

Placental perfusion MR imaging with contrast agents in a mouse model.

PURPOSE: To quantitatively analyze placental perfusion by using magnetic resonance (MR) imaging with contrast agents in a mouse model. MATERIALS AND METHODS: Study was conducted according to French law and in full compliance with National Institutes of Health recommendations for animal care. Thirty-six pregnant Balb/c mice at 16 days of gestation were injected intravenously with either a conventional or macromolecular gadolinium chelate, and 1.5-T single-section T1-weighted two-dimensional fast spoiled gradient-echo sequential MR imaging was then performed for 14 minutes. Images were analyzed qualitatively, and parametric map analysis was performed in the resultant 25 mice included in the study. Signal intensity was measured in maternal left ventricle (input function), placenta, and fetus on all images. After converting signal intensity into contrast agent tissue concentrations, a three-compartment model was developed with compartmental and numeric modeling software. Placental perfusion was calculated for conventional (n = 12) and macromolecular (n = 13) gadolinium chelates. Finally, placental and fetal gadolinium concentrations were assayed by means of atomic emission spectrophotometry (n = 15). Perfusion values and placental and fetal gadolinium concentrations for conventional and macromolecular chelates were compared by using an unpaired t test. RESULTS: Based on a constant transfer parameter, estimated placental perfusion did not differ between procedures with conventional and macromolecular gadolinium chelates (0.99 mL/min/g +/- 0.5 [standard deviation] and 1.28 mL/min/g +/- 0.6, respectively, P = .22). Likewise, mean placental gadolinium concentrations did not differ after injection of conventional and macromolecular chelates. In contrast, mean fetal gadolinium concentration was 9.83 micromol/L after conventional chelate injection and below detection limit after macromolecular chelate injection. CONCLUSION: Placental perfusion can be calculated by using dynamic contrast-enhanced MR imaging, as shown in this mouse model.

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PubMed2005

Cystathionine beta synthase deficiency affects mouse endochondral ossification.

Cystathionine beta synthase (CBS) is a crucial regulator of plasma concentrations of homocysteine. Severe hyperhomocysteinemia due to CBS deficiency confers diverse clinical manifestations, notably characteristic skeletal abnormalities. To investigate this aspect of hyperhomocysteinemia, we analyzed the skeleton of CBS-deficient mice, a murine model of severe hyperhomocysteinemia. Radiography, Alcian Blue/Alizarin Red S-stained whole skeletal preparations, and histological comparisons were used to determine the extent, pattern, and distribution of skeletal abnormalities in CBS-deficient mice. Disruption of the murine CBS gene leads to skeletal abnormalities, notably kyphoscoliosis, with temporal shortening of long bones due to impaired cartilage differentiation, albeit to differing degrees.

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PubMed2004

In vivo cellular imaging of magnetically labeled hybridomas in the spleen with a 1.5-T clinical MRI system.

The feasibility of in vivo cellular imaging using a 1.5 T clinical magnet was studied in the mouse. Hybridoma cells were labeled with anionic gamma-Fe2O3 superparamagnetic iron oxide nanoparticles. These were internalized by the endocytose pathway. Both electron spin resonance and magnetophoresis as a measure of the labeled cells migration velocity under a magnetic field were used to quantify particle uptake. A fast (< 2 hr) and substantial (up to 5 pg of iron per cell) internalization of nanoparticles by hybridomas was found, with good agreement between the two methods used. Hybridomas labeled with 2.5 pg iron per cell were injected intraperitoneally to male Swiss nude mice. A decrease in the spleen signal, suggesting a "homing" of labeled hybridomas to this organ, was found 24 hr later by MRI performed at 1.5 T. Furthermore, in labeled cells recovered from the spleen by ex vivo magnetic sorting, a mean of 0.5 pg iron per cell was found, i.e., a value five times lower than that of the injected hybridomas. This finding is consistent with in vivo proliferation of these cells. In addition, the amount of labeled hybridomas present in the spleen was found to correlate with MRI signal intensity.

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PubMed2003

Altered gene expression in liver from a murine model of hyperhomocysteinemia.

Cystathionine beta-synthase (CBS) deficiency causes severe hyperhomocysteinemia and other signs of homocystinuria syndrome, in particular a premature atherosclerosis with multiple thrombosis. However, the molecular mechanisms by which homocysteine could interfere with normal cell function are poorly understood in a whole organ like the liver, which is central to the catabolism of homocysteine. We used a combination of differential display and cDNA arrays to analyze differential gene expression in association with elevated hepatic homocysteine levels in CBS-deficient mice, a murine model of hyperhomocysteinemia. Expression of several genes was found to be reproducibly abnormal in the livers of heterozygous and homozygous CBS-deficient mice. We report altered expression of genes encoding ribosomal protein S3a and methylthioadenosine phosphorylase, suggesting such cellular growth and proliferation perturbations may occur in homozygous CBS-deficient mice liver. Many up- or down-regulated genes encoded cytochromes P450, evidence of perturbations of the redox potential in heterozygous and homozygous CBS-deficient mice liver. The expression of various genes involved in severe oxidative processes was also abnormal in homozygous CBS-deficient mice liver. Among them, the expression of heme oxygenase 1 gene was increased, concomitant with overexpression of heme oxygenase 1 at the protein level. Commensurate with the difference in hepatic mRNA paraoxonase 1 abundance, the mean hepatic activity of paraoxonase 1, an enzyme that protects low density lipoprotein from oxidation, was 3-fold lower in homozygous CBS-deficient mice. Heterozygous CBS-deficient mice, when fed a hyperhomocysteinemic diet, have also reduced PON1 activity, which demonstrates the effect of hyperhomocysteinemia in the paraoxonase 1 activity.

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PubMed2003

PCP4 is highly expressed in ectoderm and particularly in neuroectoderm derivatives during mouse embryogenesis.

PCP4 (PEP-19) belongs to a family of proteins involved in calcium transduction signals and binds calmodulin via an IQ motif, in a calcium independent manner. PCP4 gene maps to murine chromosome 16 and in human to chromosome 21. Murine PCP4 expression in the brain has been detected by Northern blot analysis to be mainly post-natal and in the adult to have a neuronal pattern. To investigate if it might have a role earlier in development, we analyzed its expression during mouse embryogenesis by in situ hybridization from E7.5 post-coitum (p.c.) to E17.5 p.c., and in P0 brain. Early, at E7.5, a high expression is restricted to the extra embryonic ectoderm. Embryonic expression starts at E9.5. At E10.5, PCP4 shows a strong signal in the post-mitotic cells of the diencephalon, the metencephalon and the myelencephalon and in the dorsal and cranial ganglia. The floor plate is also densely labelled. At E17.5, PCP4 is expressed in the central nervous system, in the myenteric plexus, and in other ectoderm derivatives, for instance the lens, the hairy cells of the cochlea, the enamel organ and the hair follicles. Thus, during embryogenesis PCP4 is mainly expressed in ectoderm and neuroectoderm comprising neural crest derived cells.

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