Biomedical subjects

Michel Vaubourdolle

Publications and source records attributed to Michel Vaubourdolle.

7 recordsLinked to original sources

PubMed2004

Effect of aging on liver functions-an experimental study in a perfused rat liver model.

BACKGROUND: Aging is associated with marked changes in the physiology of many organs. Aging of the liver has been little studied and findings are inconclusive. The purpose of this work was to determine the effect of aging on transport and metabolic functions of the liver as assessed by extraction ratio of indocyanine green (ICG) and urea flux respectively. Bile flow was also recorded. As ICG is removed exclusively by the liver without bioconversion, its clearance reflects hepatic functional mass. METHODS: Livers from adult (3-month old) or old (24-month old) rats were perfused in a recirculating system for 90 min. At time 30 min, a bolus of 0.125 mg of indocyanine green was introduced in the perfusion buffer. At least every 10 minutes, the perfusion buffer was sampled for the measurements of ICG and urea. Bile flow was closely monitored throughout the experiment. RESULTS: Extraction ratio of ICG was increased in livers from old rats (9.49 +/- 2.84 vs 3.70 +/- 1.56% of ICG extracted), whereas urea flux was diminished (0.33 +/- 0.06 vs 1.33 +/- 0.65 micromol/min/% of ICG extracted) and bile flow was unchanged (4.03 +/- 1.02 vs 3.57 +/- 1.34 microl/min). CONCLUSIONS: Aging does not affect the different functions of the liver in the same way. It increases hepatocellular uptake function, but decreases the metabolic function of hepatocytes and does not change excretion function. These discrepancies are likely to be of some importance in the study of drug metabolism and action, and so we suggest that results should be corrected for ICG extraction.

Aging↗

PubMed2004

Evaluation of the blood gas analyzer Gem PREMIER 3000.

During the past few decades, new technologies have allowed the fabrication of miniaturized sensors and the development of analyzers well designed for point-of-care testing (POCT). They combined the ease-of-use and portability required for POC with the accuracy and the reliability of traditional systems. Instrumentation Laboratory introduced the GEM Premier 3000, a compact and portable system to rapidly analyze pH, pCO2, PO2, Ca2+, Na2+, K+, lactate, glucose and hematocrit, from 135 microl of whole blood with a simple component: a cartridge, the GEM Premier Pak. The analytical performance was compared with the Radiometer ABL 725 instrument for blood gas/ electrolytes/metabolites, and for hematocrit with the centrifuged microhematocrit method. Aqueous quality control materials (Instrumentation Laboratory) were used for precision and recovery studies. The evaluation was performed according to the Valtec protocol, designed by the French Society of Clinical Biology, for imprecision, linearity and accuracy. With-in-run and between-run imprecisions for all the parameters gave good CV values. Linearity was good and results comparison showed close agreement with correlation coefficients between 0.91 and 0.99. The analyzer is very easy to use; the simplicity and the convenience of only one consumable make the GEM Premier 3000 very suitable for a STAT laboratory or for POCT.

Blood Gas Analysis↗

PubMed2003

Proteomic study of human umbilical vein endothelial cells in culture.

The endothelium is a single layer of cells lining the inside face of all blood vessels. It constitutes a major metabolic organ which is critically involved in the generation and the regulation of multiple physiological and pathological processes such as coagulation, hemostasis, inflammation, atherosclerosis, angiogenesis and cancerous metastasis dissemination. In order to increase our knowledge about the protein content and the main biological pathways of human vascular endothelial cells, we have undertaken the proteomic analysis of the most explored present endothelial cell model, i.e. primocultures of human umbilical vein endothelial cells (HUVECs). Using low levels of protein loads (~ 30 nug), the association of two-dimensional electrophoresis with matrix-assisted laser desorption/ionization-time of flight mass spectrometry, liquid chromatography-tandem mass spectrometry and database interrogations allowed us to identify 53 proteins of suspected endothelial origin in quiescent HUVECs. Beside cytoskeletal proteins such as actin, tubulin, tropomyosin and vimentin, we identified various proteins more especially implicated in cellular motility and plasticity (e.g. cofilin, F-actin capping protein and prefoldin), in regulation of apoptosis and senescence (protease inhibitor 9, glucose related proteins, heat shock proteins, thioredoxin peroxidase, nucleophosmin) as well as other proteins implicated in coagulation (annexin V, high mobility group protein), antigen presentation (valosin containing protein and ubiquitin carboxyl terminal hydrolase isozyme L1) and enzymatic capabilities (glutathione-S-transferase, protein disulfide isomerases, lactate deshydrogenase). The presented annotated 2-D maps of HUVECs will be soon available on the web at http://www. huvec.com.

Cells, Cultured↗

PubMed2003

Captopril and enalaprilat decrease antioxidant defences in human endothelial cells and are unable to protect against apoptosis.

Angiotensin-converting enzyme (ACE) inhibitors were shown to improve endothelial dysfunction in various human diseases and some of these inhibitors have been proposed as enhancers of antioxidant defences. We measured glutathione peroxidase (GPX), superoxide dismutase (SOD) and malondialdehyde (MDA) in human endothelial cells treated with captopril or enalaprilat, two ACE inhibitors, and we showed that both inhibitors decreased GPX and SOD activities but not MDA, the end-product of lipoperoxidation. Captopril and enalaprilat were also unable to protect against etoposide-induced apoptosis in endothelial cells, indicating that they cannot be considered as protective drugs for the endothelium, in particular in clinical situations involving oxidative stress or apoptosis. Moreover, when used at high concentration captopril, but not enalaprilat, was toxic for endothelial cells with both necrotic and apoptotic effects.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Osmolar gap hyponatremia in critically ill patients: evidence for the sick cell syndrome?

OBJECTIVE: Accumulation of nondiffusible solutes in plasma leads to redistribution hyponatremia with an increased osmolar gap (i.e., the difference between measured and calculated osmolality). In critically ill patients, intracellular solutes may leak out of the cell because of an increased membrane permeability and may lead to redistribution hyponatremia with increased osmolar gap, a concept called the "sick cell syndrome." The aims of this prospective study were to determine whether an increased osmolar gap related to endogenous solutes accumulation was present in intensive care patients with true hyponatremia and to identify the solutes accounting for this increased osmolar gap. SETTING: A 14-bed medical intensive care unit in an 821-bed university hospital. DESIGN: A 20-wk prospective observational study. PATIENTS: Fifty-five consecutive patients with a measured plasma sodium concentration 10 mosm/kg. Total plasma amino acid concentration also was measured. Organ dysfunctions were assessed with the Sequential Organ Failure Assessment. Thirty of the 55 patients (54%) had an osmolar gap >10 mosm/kg (17.2 +/- 7.1 mosm/kg). Sequential Organ Failure Assessment score was significantly higher in the osmolar gap patients (6.4 +/- 3.2 vs. 4.5 +/- 2.0; p =.015). No difference of amino acids concentration was observed between osmolar gap and non-osmolar gap patients, and no correlation was observed between osmolar gap and amino acid concentration. Accumulation of ketone bodies and lactic acid was also unlikely. During correction of hyponatremia in osmolar gap patients, a significant decrease of plasma osmolar gap was observed and a statistically significant inverse relationship was demonstrated between osmolar gap decrease and plasma sodium concentration increase. CONCLUSION: Hyponatremia with increased osmolar gap related to endogenous solutes accumulation is observed frequently in hyponatremic intensive care patients, especially in patients with the most severe organ dysfunctions. The nature of the endogenous solutes accounting for the increased osmolar gap remains to be determined. Simultaneous correction of sodium and osmolar gap suggests a causal link between increased osmolar gap and hyponatremia and may support the concept of sick cell syndrome.

Amino Acids↗

PubMedDate not supplied

Cyclosporin A but not estradiol can protect endothelial cells against etoposide-induced apoptosis.

This study was undertaken to examine the possibilities of endothelial protection toward toxicity of anticancer drugs. To test the hypothesis that estradiol (E2) and cyclosporin A (CsA) can interfere within programmed cell death in human umbilical vein endothelial cells (HUVECs), apoptosis was induced by etoposide with and without E2 or CsA. All the concentrations of E2 tested (from 10(-9) to 10(-5) M) failed to protect HUVECs. For CsA a dual effect was observed: used at 1 or 10 microg/mL in coincubation with etoposide, CsA significantly reduced etoposide-induced apoptosis but complete inhibition was not reached, whereas used at 50 microg/mL CsA did not protect HUVECs anymore and even had deleterious effects. Furthermore, a 24-h pretreatment of HUVECs by CsA at 10 microg/mL significantly protected the cells by preventing both bcl-2 level decrease and caspase-3 activation related to etoposide-induced apoptosis. Protective effects of CsA toward endothelial cells were concentration dependent; in pretreatment at 10 microg/mL, CsA was an effective protector and might contribute in vivo to inhibit obvious toxic effects caused by anticancer drugs.

Antineoplastic Agents, Phytogenic↗

PubMedDate not supplied

Development of an internal dynamic web site to promote quality assurance in a clinical laboratory.

In clinical laboratories, one challenging quality assurance objective is to maintain standardized practices. Meeting this objective entails ensuring information flow, which is necessary to smooth running of the laboratory. To facilitate information flow, we developed an internal quality Web site on our local network. The dynamic generated pages of the site were constructed with EasyPHP v.1.6, a complete freeware package providing PHP dynamic language and databases. The site comprises various sections: general news, specific laboratory units news, documents (quality manual, guidelines, emergency processes), schedules, National Quality Control results, forum, etc. Five to 10 pages are updated each week. This work was facilitated by the use of PHP-written pages and data tables, which enable us to record in real time the operation of our assurance quality project and to improve traceability. This approach could be extended to other aspects of quality management and could help meet the future IS015189 standard requirements.

Computer Communication Networks↗