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Biomedical subjects

L Drouet

Publications and source records attributed to L Drouet.

140 records · Page 8Linked to original sources
PubMed1980

[Interactions between the platelets and the vessel wall. Part 1: Physiology (author's transl)].

The vessel wall plays an important role in the maintenance of balance between haemorrhage and thrombosis. The endothelial lining of a normal vessel wall is thrombo-resistant, in particular by virtue of prostacyclin, whilst the sub-endothelium with its collagen is thrombogenic. If the endothelium is pathologically or experimentally damaged, adhesion of the blood platelets becomes possible. This mechanism, presently studied at a molecular level itself, involves the Willebrand factor, the glycoproteins of the platelet membrane and constituents of the sub-endothelium which remain poorly defined. Platelet adhesion is responsible for cellular activation with the liberation of numerous intraplatelet constituents and synthesis of prostaglandins. Agregation between platelets involves complex biochemical phenomena which concern the platelet membrane and fibrinogen, contractile proteins and the cyclic AMP system, prostaglandins and ADP. The role of calcium in these different phenomena is very important.

Adenosine Diphosphate↗
PubMed1977

Uptake of noradrenaline in high altitude native's heart.

Uptake of 3H-noradrenaline by the heart was studied with sections of isolated atria obtained from high or lowlanders. In native highlanders, affinity for 3H-noradrenaline by human atria is more significant than in lowlanders. Furthermore, the Michaelis Menten constant is lower in high altitude native's heart.

Adaptation, Physiological↗
PubMed1977

Splanchnic blood flow, O2 consumption, removal of lactate, and output of glucose in highlanders.

An impairment of gluconeogenesis has been proposed to explain the low arterial blood glucose of highlanders. Therefore, we studied splanchnic blood flow, splanchnic uptake of oxygen and lactate, and output of glucose in nine normal and six anemic highlanders at an altitude of 3,750 m. Splanchnic blood flow, arteriovenous difference for oxygen, and oxygen consumption were comparable at rest in both groups and in lowlanders from the literature, whereas splanchnic output of glucose, and uptake of lactate were approximately twice those in lowlanders. After 10 min of mild exercise in 12 subjects (7 normals, 5 anemic), no significant changes in splanchnic hemodynamics and metabolism were found. During 29% oxygen breathing in 8 subjects (5 normals, 3 anemics), arterial lactate, splanchnic uptake of lactate and output of glucose fell to normal sea-level values. We concluded that splanchnic hemodynamics are similar in adapted highlanders and in lowlanders, and that there is no evidence of an impaired gluconeogenesis at the altitude of the present study.

Adaptation, Physiological↗
PubMed1975

[Muscular blood flow in human highlanders and in lowlanders living at altitude (3 800 m) (author's transl)].

Muscular blood flow (MBF) was measured in the tibialis anteiror muscle by the 133Xe washout technique. Measurements were made in lowlanders at sea level, in native highlanders at 3 800 m and in lowlanders who had been living at this altitude for less than 6 months. At rest and during exercise, MBF is smaller in highlanders and in the high altitude visitors than in lowlanders. If, instead of total blood flow, the red cell flow is calculated (by multiplying MBF by the haematocrit) these differences are no longer significant at rest and are minimized during exercice. These results are consistent with reduction of cardiac output and blood supply to other regions in subjects who are acclimatized to altitude.

Adult↗
PubMedDate not supplied

Phenotypic and functional characteristics of porcine peritoneal mesothelial cells.

The objective of this study was to establish a technique to isolate porcine mesothelial cells (PMCs) from omental tissue and to compare them to human mesothelial cells (HMCs). The PMCs were dispersed by collagenase digestion and isolated on a Ficoll layer. Their morphologic and ultrastructural features were assessed at confluence by light and electronic microscopy, and they were characterized by immunohistochemistry using specific HMC markers. PMC proliferation was studied in the presence of growth factors platelet-derived growth factor (PDGF), epidermal growth factor (EGF) or transforming growth factors beta1, beta2, or beta3 (TGF). Fibrinolytic PMC activity was detected by zymography for tissue plasminogen activator (tPA) and by reverse zymography for plasminogen activator inhibitor-1 (PAI-1). The recalcification time of cell lysates was used to define PMC procoagulant activity, and gelatinase zymography was used to detect metalloproteinase production. At confluence, PMCs formed typical cobblestone monolayers and exhibited structural features characteristic of HMCs. Weibel Palade bodies were never seen. Specific HMC markers (HBME1, ME1, WT1) cross-reacted with PMCs. As HMCs and PMCs coexpressed cytokeratin and vimentin, and also expressed vinculin and alpha-actin. Addition of PDGF or EGF to the culture medium stimulated PMC proliferation. PMCs constitutively expressed fibrinolytic and procoagulant activity and secreted MMP9 and MMP2. The technique described in this study allows isolation of mesothelial cells from porcine omental tissue. These porcine cells exhibit a mesothelial phenotype and functional properties similar to those of HMCs. Our data warrant an evaluation of mesothelial cells as targets in several therapeutic strategies with porcine models.

Animals↗
PubMedDate not supplied

Purification and analysis of lung and plasma angiotensin I-converting enzyme by high-performance liquid chromatography.

We purified angiotensin I-converting enzyme (ACE) from pig and human lung and plasma for comparison of some physicochemical properties between the endothelial membrane-bound form and the soluble form of the enzyme. After affinity chromatography on Sepharose CL-4B/lisinopril, gel-filtration HPLC on Superose 12 achieved homogeneity for both forms as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Whatever the source of ACE, the molecular weight was 300 +/- 40 kDa after calibration of Superose 12 with standard globular proteins and 172 +/- 4 kDa by SDS-PAGE, with or without reduction, a result suggesting interactions between the glycopolypeptide chain and the chromatographic gel possibly related to the overall shape and sugar content of the enzyme. Ion-exchange HPLC analysis on TSK-DEAE showed that the membrane-bound and soluble forms of ACE are not isoenzymes, although isoelectrofocusing did show that the isoelectric point of soluble ACE was lower than those of tissue ACE, suggesting a different glycosylation. No significant difference between porcine and human ACE appeared. HPLC methods seem to be of particular interest for the purification of ACE with a high yield and for the analysis of its putative differently glycosylated isoforms.

Animals↗
PubMedDate not supplied

In vitro synthesis of DNA, protein, and lipids by the de-endothelialized rabbit aorta.

The uptake of [3H] leucine, [3H] thymidine, [14C] acetate, and [14C] mevalonic acid by aortic intima media from normal rabbits and from rabbits subjected to a single balloon de-endothelialization as measured 6 days, 2 months, and 4 months after treatment to determine how long the injury-induced stimulation of incorporation of these precursors into tissue components persisted beyond 6 days, the time of maximum proliferative response of the smooth muscle cells. We found that [3H] thymidine incorporation (indicative of DNA synthesis and the potential for cell proliferation) was about three times greater in the de-endothelialized tissue than in the control tissue 6 days after vessel injury, but that by 2 months it was normal. Labeled leucine incorporation into the de-endothelialized tissue (a measure of protein synthesis) was eight times higher than normal at the time of maximum proliferative response to injury (6 days), and showed no decrease under identical incubation conditions in ballooned tissue obtained 2 months after de-endothelialization; it continued high at 4 months. Both [14C] acetate and [14C] mevalonate uptake into lipids by the aortic tissue were enhanced by the injury; this increased incorporation was still evident at 4 months. Thus, de-endothelialization of the aorta triggers a vessel wall response characterized by augmented protein synthesis and lipogenesis, which persists at least 4 months after injury and at least 2 months after DNA synthesis has normalized.

Animals↗
PubMedDate not supplied

Differential distribution of von Willebrand factor in endothelial cells. Comparison between normal pigs and pigs with von Willebrand disease.

Endothelial cells were cultured from the thoracic aorta, inferior vena cava, and pulmonary artery of normal adult and young pigs as well as from pigs with von Willebrand disease (vWD). The von Willebrand factor (vWF) was estimated by ELISA in endothelial cell supernatants and lysates as well as by immunofluorescence of cells by use of either a polyclonal or a monoclonal antibody to vWF. In normal adult pigs, the content of vWF in supernatants and cell lysates was the highest in the pulmonary artery, lower in the inferior vena cava, and almost nil in the thoracic aorta. In the normal young pigs, vWF was higher in the inferior vena cava endothelial cell supernatants and lysates than in the pulmonary artery. Thus the synthesis of vWF by endothelial cells varies along the vascular tree and appears to be modulated by the age of the animals. In pigs with vWD, levels of vWF were slightly detectable in endothelial cells from the pulmonary artery (contrasting with levels of plasmatic vWF below 0.01 U/ml), but were undetectable in the thoracic aorta and inferior vena cava. Thus, if vWF plays a role in atherogenesis, this involves circulating, not its intracellular, form.

Aging↗
PubMedDate not supplied

Nonviral gene transfer into primary cultures of human and porcine mesothelial cells.

Due to their abundance and accessibility, mesothelial cells may be suitable tools for recombinant reagent expression by gene transfer. Genetically modified porcine mesothelial cells (PMCs) may have the potential for the treatment of vascular diseases in humans. We studied the effect of various transfection reagents on the primary culture of PMCs and human mesothelial cells (HMCs). The cells were transfected with a plasmid encoding a reporter gene (luciferase or green fluorescent protein [GFP]) under the control of the cytomegalovirus promoter. Transfection was achieved using cationic lipids (DOSPER and DOTAP) or calcium phosphate/deoxyribonucleic acid coprecipitation or Fugene 6. Results showed that Fugene 6 was the most efficient and reproducible transfection reagent with both PMCs and HMCs. With Fugene 6, luciferase activity in PMCs (1.5 x 10(8) relative light units [RLU]/10(6) cells) was at least 2.5-fold higher than with the other transfection reagents, and it was 100-fold higher than in HMCs. However, the proportion of transfected cells expressing GFP was only 1%. These preliminary findings open up new avenues for developing experimental studies on the use of genetically modified PMCs.

Animals↗
PubMedDate not supplied

[Veno-occlusive disease of the liver after bone marrow transplantation. Report of the symposium Autograft in France and the group of study of bone marrow transplantation. France Auto-Greffe et le Groupe d'Etude de la Greffe de Moelle osseuse].

Hepatic veno-occlusive disease is a frequent complication after high-dose chemo- or radiotherapy after bone marrow transplantation and is a major cause of mortality. During the 3 weeks following transplantation, acute major hepatic vascularization is observed together with portal hypertension and weight gain, ascitis and oedema of the lower limbs due to non-thrombotic obstruction of the centrilobular hepatic veins. This report summarizes the observations presented at a French symposium of France Autogreffe and Groupe d'Etude de la Greffe de Moelle osseuse. Different pathogenic processes are implicated including endothelial mechanisms due to toxic factor related to graft preparations and immunosuppressor treatments (methotrexate, cyclosporin), physical factors related to irradiation, immunological factors related to the expression of class II antigens on endothelial cells and viral factors, in particular cytomegalovirus infection. The incidence of veno-occlusive disease varies greatly from one series to another. Two French groups reported 5 and 3 cases among 1991 and 253 autologous grafts respectively (1.2 and 2.3%) while the Seattle group observed 53% among 355 consecutive grafts, although the same clinical criteria were used. Histological criteria include fibrosis around a non-thrombotic occlusion of the centrilobular veins, cytolysis and congestion of the sinuses. Other methods for diagnosis include transjugular biopsy, the suprahepatic pressure and imaging techniques. Prophylactic continuous infusion of low-dose heparin has been associated with a lower incidence. Trials using anti-tumour necrosis drugs and prostaglandin E1 have also been undertaken and show possible effects towards decreasing prevalence.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗