Biomedical subjects

Philippe Marchand

Publications and source records attributed to Philippe Marchand.

8 recordsLinked to original sources

PubMed2006

Influence of biological and ecological factors on the bioaccumulation of polybrominated diphenyl ethers in aquatic food webs from French estuaries.

Previous studies have shown the worldwide presence of six congeners of polybrominated diphenyl ethers (PBDEs) in marine biota (BDE-28, -47, -99, -100, -153 and -154). The objective of the present study was to document their presence, their level and their transfer in the food web of two major estuaries in France, the Loire and the Seine. PBDEs were quantified in eight principal species from the Loire, representing primary consumers (the bivalve Scrobicularia plana), omnivores (the worm Nereis diversicolor, the shrimps Crangon crangon, Palaemon elegans and Palaemon serratus, the flatfish Platichthys flesus and Solea solea) and supercarnivores (the eel Anguilla anguilla). In the Seine, only worms, bivalves, sole and eels have been studied. Parameters, which can interfere with the interpretation of contamination data (organ distribution, influence of weight or size of specimens, lipid richness, intrinsic variability), have been examined. BDE-47 was the predominant congener in all biota. Higher contamination was observed in most of the species collected from the Seine, in agreement with the higher human presence and economic activity in the Seine than in the Loire basin. PBDEs have been shown to biomagnify in both of the studied estuarine food webs. However, assessment of PBDE transfer from seafood products exposed to contaminants in the Seine estuary showed that human daily intake is far below the no observed adverse effect levels.

Anguilla↗

PubMed2006

Use of optophoresis as an in vitro predictor of cell response to chemotherapy for chronic lymphocytic leukemia.

B-cell chronic lymphocytic leukemia [CLL] is characterized by active accumulation of clonal CD5+/CD19+/CD23+ B cells. Individualized characterization of patient cell resistance/sensitivity to specific agents can provide important information to guide therapy selection. We have utilized optophoresis, which is a technique for the analysis of the motion of cells within a moving optical gradient field. It detects the broad cellular changes associated with apoptosis based on physical characteristics of the cell, such as morphology, size, refractive index, density, and surface properties. We analyzed peripheral blood samples from 62 CLL patients in the presence of varying concentrations of chemotherapeutic agents. Optophoresis and a more conventional measurement of cell death were utilized. The outcome of ex vivo drug resistance using optophoresis was compared to clinical response in 30 patients for which there was clinical outcome data available. The overall accuracy of optophoresis in reflecting clinical response was 80%. It has advantages over alternative methods of determining chemoresistance including the ability to evaluate very small sample sizes and ability to work in mixed-cell populations. Changes in cell physical characteristics in response to chemotherapy, as measured by optophoresis is an accurate method for predicting chemosensitivity ex vivo in CLL.

Adenosine Triphosphate↗

PubMed2005

PCDD/F and PCB transfer to milk in goats exposed to a long-term intake of contaminated hay.

The purpose of this study was to determine the feed to milk transfer of 17 PCDD/Fs and 18 PCBs in goats exposed to a 10-week long-term intake of contaminated hay collected in the vicinity of a hazardous municipal waste incinerator. The sum of PCDD/Fs and PCBs WHO-I-TEQ was found to be higher than 3 ng kg(-1) of milk fat after the first experimental week. Carry-over rates (CORs) of PCDD/Fs and PCBs could be established at steady state conditions for each compound studied. For PCDD/Fs, 2,3,7,8-TCDD appeared as the compound having the highest COR (38.8%). Within dioxin-like-PCBs the highest COR were found at a similar level (higher than 80%) for PCBs 105, 118 and 157. Concerning indicator-PCBs, COR ranged from 5% (PCB 101) to more than 40% (PCBs 118, 153 and 180). The intensity of this transfer appeared to be a function of physico-chemical properties (chlorination or logK(ow)) of the molecules and their metabolic behaviour.

Animal Feed↗

PubMed2005

Studying variations in the PCDD/PCDF profile across various food products using multivariate statistical analysis.

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are widely recognized by the scientific community as persistent organic pollutants due to their toxicity and adverse effects on wildlife and human health. The actual regulation dedicated to the monitoring of dioxins in food is based on the measurement of 17 congener concentrations. The final result is reported as a toxic equivalent value that takes into account the relative toxicity of each congener. This procedure can minimize the qualitative information available from the abundances of each PCDD/PCDF congener: the characteristic contamination profile of the sample. Multivariate statistical techniques, such as principal component analysis (PCA) or linear discriminant analysis (LDA), represent an interesting way to investigate this qualitative information. Nevertheless, they have only been applied to the analysis of contamination data from food products and biological matrices infrequently. The objective of the present study was to analyze a large data set from dioxin analyses performed on various food products of animal origin. The results demonstrate the existence of differences in congener-specific patterns between the analyzed samples. Variability was first demonstrated in terms of the food type (fish, meat, milk, fatty products). Then a variability was observed that was related to the specific animal species for meat and milk samples (bovine, ovine, porcine, caprine and poultry). Some practical applications of these results are discussed. The origin(s) of the observed differences, as well as their significance, now remain to be investigated, both in terms of environmental factors and transfer through living organisms. A better knowledge of the relation between a contamination profile and its specific source and/or food product should be of great interest to scientists working in the fields of contaminant analysis, toxicology and metabolism, as well as to regulatory bodies and risk assessors in charge of final decisions regarding the eventual hazards associated with theses substances.

Animals↗

PubMed2005

New multiresidue analytical method dedicated to trace level measurement of brominated flame retardants in human biological matrices.

A new method has been developed for the multi-residue measurement of the main brominated flame retardants (alpha- and gamma-hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBP-A) and polybrominated diphenyl ethers including decabromodiphenyl ether) in human biological matrices (serum, adipose tissue and breast milk). The proposed sample preparation procedure focused on reduced solvent and consumable consumption and associated procedural contamination, as well as reduced sample size. This protocol was fully validated and was proved to be suitable for identification of brominated flame retardant residues at ultra-trace level, as attested by preliminary results on real samples.

Adipose Tissue↗

PubMed2005

Tissue distribution and bioconcentration factors of PCDD/Fs in the liver and adipose tissue following chronic ingestion of contaminated milk in rats.

The aim of this study was to determine the tissue distribution of 17 PCDD/Fs following the chronic ingestion of contaminated milk in rats and to assess the "target tissue/milk" BioConcentration Factors (BCFs) of these molecules. Contaminated milk, collected in a polluted area, has been incorporated into the diet of male rats at a low dose (31 pg I-TEQ/day/rat). For this exposure, the accumulation of PCDD/Fs in target tissues (liver and adipose tissue) was limited, the tissue concentrations stabilising between 90 and 120 days of daily intake to levels close to 3 pg/g of tissue (all tissues and molecules combined). The tissue distribution seemed to be governed by the congeners properties and by the tissue characteristics. An increase in the chlorination degree of dioxins caused a decrease in their incorporation in the adipose tissue, and consequently of the BCF values. Moreover, the distribution of dioxins between hepatocytes and adipocytes differed: unlike the liver, the quantities of dioxins in the adipose tissue were significantly (P<0.05) correlated to the quantity of tissue fat. Only in the liver, the incorporation of PCDDs seemed to be facilitated when the chlorination degree of these congeners increased, the reverse phenomenon having been observed for PCDFs. However, for the same level of chlorination, the BCFs of PCDFs were 2.4 times higher than those of PCDDs in this tissue. The absence of correlation between the quantity of dioxins and that of fat and the BCFs differences of theses congeners suggested that dioxins fixation process in the liver was selective.

Adipose Tissue↗

PubMed2004

Elastic light scattering from single cells: orientational dynamics in optical trap.

Light-scattering diagrams (phase functions) from single living cells and beads suspended in an optical trap were recorded with 30-ms time resolution. The intensity of the scattered light was recorded over an angular range of 0.5-179.5 degrees using an optical setup based on an elliptical mirror and rotating aperture. Experiments revealed that light-scattering diagrams from biological cells exhibit significant and complex time dependence. We have attributed this dependence to the cell's orientational dynamics within the trap. We have also used experimentally measured phase function information to calculate the time dependence of the optical radiation pressure force on the trapped particle and show how it changes depending on the orientation of the particle. Relevance of these experiments to potential improvement in the sensitivity of label-free flow cytometry is discussed.

Cell Polarity↗

PubMed2002

Identification of ractopamine residues in tissue and urine samples at ultra-trace level using liquid chromatography-positive electrospray tandem mass spectrometry.

Beta-agonist compounds are widely used in human therapeutics because of bronchodilator or heart tonic properties; they are also used as growth promoters in food-producing animals. Ractopamine is a forbidden molecule in the EU, but is registered as an additive in other countries such as in the USA for pigs. Consequently, efficient analytical methods were developed to survey residues in edible tissue and urine samples. This paper describes a protocol based on a powerful extraction and purification process and a liquid chromatography-positive electrospray mass spectrometry identification method. A validation was performed according to the "DG SANCO 1805/2000" European decision. The obtained decision limit (CCalpha) and detection capability (CCbeta) were as low as 10 and 30 ng/kg (ppt), respectively. This method appeared very efficient on incurred samples, including porcine edible tissues (meat, liver, kidney), tissues enriched in beta-agonist receptors (lung, retina), and finally bovine urine samples.

Adrenergic beta-Agonists↗