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Biomedical subjects

A Bourdon

Publications and source records attributed to A Bourdon.

17 recordsLinked to original sources
PubMed2003

Colloid transport in nonuniform temperature.

The aim of this paper is to set up a theoretical framework for obtaining the thermodiffusion (or Soret) coefficient of a colloid in a carrier liquid. It is first argued that the expression of the particle-current density in nonuniform temperature cannot be derived from a theoretical formula valid for an isothermal solution. Then the kinetic theory of Brownian motion is used to derive an expression for the current density properly accounting for thermodiffusion. The cases of free and interacting particles are treated, and the thermodiffusion current pertinent to an ideal solution adds up with a current driven by a temperature- and concentration-dependent potential. Accordingly, a general explicit formula for the thermodiffusion coefficient is obtained. Practical use of the framework is illustrated on simple specific models of a colloid in a solvent. Large Soret coefficients of both signs are calculated for realistic values of the physicochemical parameters, in qualitative agreement with published experimental data.

Journal Article↗
PubMed2002

Thermodiffusion in magnetic colloids evidenced and studied by forced Rayleigh scattering experiments.

This paper shows how forced Rayleigh scattering can be used as an experimental tool for studying thermodiffusion (Soret effect). The systems investigated are magnetic colloids of different types. A framework including thermodiffusion and dielectrophoresis is described in which the evolutions of temperature and of colloid concentration are clearly distinguished. The framework is then shown to account for experiments on steady-state concentration gratings coupled with transient temperature ones, and the parameters are determined therefrom. Dielectrophoretic forces are found to be negligible. Studying different types of magnetic colloids with various dilution rates shows that the sign of the Soret effect is controlled by the nature of the particle coating made up of electrostatic charges or of surfactant, and that its mechanism is located at the nanoparticle core-solvent interface.

Journal Article↗
PubMed2001

Direct evidence that leukemic cells present HLA-associated immunogenic peptides derived from the BCR-ABL b3a2 fusion protein.

The BCR-ABL oncogene is central in the pathogenesis of chronic myeloid leukemia (CML). Here, tandem nanospray mass spectrometry was used to demonstrate cell surface HLA-associated expression of the BCR-ABL peptide KQSSKALQR on class I-negative CML cells transfected with HLA-A*0301, and on primary CML cells from HLA-A3-positive patients. These patients mounted a cytotoxic T-lymphocyte response to KQSSKALQR that also killed autologous CML cells, and tetramer staining demonstrated the presence of circulating KQSSKALQR-specific T cells. The findings are the first demonstration that CML cells express HLA-associated leukemia-specific immunogenic peptides and provide a sound basis for immunization studies against BCR-ABL.

Adult↗
PubMed1992

[Prognostic value after 1 year of post-infarction exercise test with measurement of oxygen consumption].

A symptoms-limited exercise stress test with measurement of myocardial oxygen consumption (VO2) was carried out in 56 patients on the 44th +/- 16 days after infarction and in 48 patients on the 119th +/- 31 days. Analysis of the expired gases was performed by mass spectrography, cycle by cycle. The second test was coupled with an exercise gamma-angiography in 40 cases. The parameters on exercise were analysed in two groups at one year: group 1 asymptomatic and group 2 symptomatic (subgroup 2a with angina but no dyspnoea, subgroup 2b with dyspnoea). At the second test, the peak VO2 was lower in group 2 (19.46 +/- 5.78 ml/mn/kg) than in group 1 (24.2 +/- 6.5 ml/mn/kg) (p less than 0.008) irrespective of the symptom (angina and/or dyspnoea). The oxygen pulse was lower in group 2a with angina at one year (42.4% +/- 14.3%) compared with asymptomatic group 1 patient (58.5 +/- 12.4%) (p = 0.03). The 3 parameters: VO2, blood pressure and ejection fraction on exercise were independent. The lack of physical fitness may partially explain the absence of variation of the peak VO2 at the first test. These preliminary results should be confirmed by a multivariate analysis in a larger patient group.

Aged↗
PubMed1990

Histologic study of peritoneal endometriosis in infertile women.

The present study included 118 patients undergoing a laparoscopy for infertility. In 86 patients with laparoscopically diagnosed endometriosis (group I), biopsies were taken from areas of apparent endometriosis (n = 86) and from a visually normal peritoneum (n = 52). Histology reveals the presence of endometriosis in 93% of positive sites and in 13% of negative sites. In 32 patients without endometriosis at laparoscopy (group II), biopsies were taken from normal uterosacral ligaments (n = 32). Endometriosis was observed in 6% of cases. Despite the increased ability to detect pigmented and nonpigmented endometriotic lesion, histological study revealed the presence of endometriosis in normal peritoneum in 13% (group I) and 6% (group II) of cases.

Biopsy↗
PubMed1983

Pharmacological interaction between nitroglycerin and aspirin after acute and chronic aspirin treatment of healthy subjects.

The interaction between nitroglycerin (NTG) and aspirin was investigated in 7 healthy subjects in order to test whether aspirin could block the haemodynamic response to NTG; the doses used were NTG 0.8 mg, and aspirin 0.5 g for chronic and 1 g for acute treatment. The plasma levels of NTG and various physiological parameters (heart rate, diastolic arterial pressure, end diastolic diameter, and end systolic diameter) were measured during the 30 minutes after the administration of NTG. An increase in NTG Cmax and AUC was observed after both aspirin treatment. The changes in physiological parameters produced by NTG were enhanced by the two treatments, although the differences were not statistically significant. The results indicate complex pharmacokinetic and pharmacodynamic interactions between NTG and aspirin.

Adult↗