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Biomedical subjects

D Ledoux

Publications and source records attributed to D Ledoux.

30 records · Page 2Linked to original sources
PubMed1997

Inhibition of human breast epithelial HBL100 cell proliferation by a dextran derivative (CMDB7): interference with the FGF2 autocrine loop [corrected].

Fibroblast growth factor 2 (FGF2) has been shown to be an autocrine growth factor in human breast epithelial cells HBL100. Here we studied the effects of one dextran derivative (CMDB7) on this autocrine loop. CMDB7 caused a dose-dependent decrease of HBL100 growth in serum-free medium. [3H]thymidine uptake in HBL100 cells and Balbc/3T3 cells by exogenous FGF2 was inhibited by CMDB7. Receptor binding assays with radio-iodinated FGF2, IGF1, EGF showed that CMDB7 only displaced the binding of 125I-FGF2 in a dose dependent manner. Scatchard analysis revealed that the presence of CMDB7 reduced 78% and 82 % FGF2 binding capacity to its high and low affinity receptors respectively without altering the affinites of binding sites. These results suggest that CMDB7 exert its antiproliferative action on HBL100 cells by interfering with FGF2 autocrine loop.

3T3 Cells↗
PubMed1997

Cellular distribution of the angiogenic factor heparin affin regulatory peptide (HARP) mRNA and protein in the human mammary gland.

The heparin affin regulatory peptide (HARP) growth factor, also known as pleiotrophin, is a developmentally regulated protein that displays biological functions during cell growth and differentiation. To study the physiological role of this protein, we investigated the cellular distribution of HARP mRNA and protein in the resting human mammary gland. In situ hybridization histochemistry revealed that HARP mRNA was localized in alveolar myoepithelial cells, whereas alveolar epithelial cells were negative. In the stroma, HARP mRNA was localized in endothelial cells and smooth muscle cells of blood vessels. Interestingly, HARP protein and mRNA were not always co-localized. HARP protein immunocytochemistry staining was observed in an area including both alveolar myoepithelial and epithelial cells, although epithelial cells do not express HARP transcript. In contrast, the distribution of HARP protein is parallel to that of HARP mRNA in endothelial and vascular smooth muscle cells. In the light of these results, the putative role of HARP in controlling the proliferation and/or differentiation of the different mammary cell types is proposed and discussed.

Blotting, Western↗
PubMed1996

Collagen abnormalities in conjunctiva of patients with cicatricial pemphigoid.

The purpose of this study was to analyze the distribution and types of collagen in the substantia propria of the conjunctiva of patients with ocular cicatricial pemphigoid (OCP). Biopsy specimens were collected from 10 patients with active OCP, five patients with active Behçet's disease, nine patients with atopic keratoconjunctivitis, five patients with chronic rosacea blepharoconjunctivitis, and six normal patients undergoing cataract surgery. Cryostat tissue sections were cut and stained using an indirect immunofluorescence technique, employing a panel of primary antibodies directed against seven collagen types. Differences between OCP, Behçet's, and normal conjunctiva were seen in the staining for collagen types III, IV, and VII. The intensity of staining for type III collagen was increased in the substantia propria of OCP conjunctiva as compared to the other groups. The basement membrane zone (BMZ) of OCP patients was typically disrupted and fragmented in appearance when stained for type IV collagen, a finding not seen in the non-OCP specimens. The BMZ staining pattern for type VII collagen in OCP conjunctiva was even more disrupted than that seen for type IV collagen, particularly on the posterior side, which was thickened and reduplicated with short fibers extending into the superficial stroma. The production of type III collagen by fibroblasts of the substantia propria is a common feature of diseases associated with subepithelial fibrosis. The damage to the epithelial BMZ and the subsequent attempt at repair with aberrant type IV and VII collagen production are unique to conjunctiva affected by OCP.

Collagen↗
PubMed1995

Effect of plasma anticonvulsant level on pipecuronium-induced neuromuscular blockade: preliminary results.

Patients receiving anticonvulsants are resistant to nondepolarizing muscle relaxants (NDMR). This study examines the effect of plasma anticonvulsant levels on pipecuronium-induced neuromuscular blockade. Twenty adult patients scheduled for neurosurgery were assigned to one of two groups. Group 0 (G0) consisted of 10 patients not on anticonvulsant therapy; group 1 (G1) included 10 patients treated either with phenytoin or carbamazepine. G1 patients were further divided into G1u (n = 4) and G1w (n = 6) subgroups, according to the plasma anticonvulsant level measured the day before surgery--under (G1u) or within (G1w) the therapeutic range. Neuromuscular transmission was monitored with a Biometer International A/S Accelograph. Anesthesia was induced and maintained using propofol and sufentanil. After calibration of the accelograph, a bolus of pipecuronium 0.08 mg/kg was given IV. The time from pipecuronium injection to the peak reduction of T1 was taken as the onset time. The time in min from pipecuronium injection to recovery of T1% (first accelograph response/baseline response) x 100 and TR% (fourth accelograph response/first accelograph response) x 100 were recorded at 25, 50, and 75% of baseline. The recovery index (RI) was taken as the time from 25 to 75% of baseline. The recovery index (RI) was taken as the time from 25 to 75% recovery of the baseline response. The onset time was not different in G0 (203 +/- 60.4 s), G1 (230.5 +/- 79.3 s), and G1u (181.8 +/- 60.4 s) but prolonged in G1w (279.2 +/- 67.7 s).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Interactions of FGFs with target cells.

Growth factors play a key role in cellular communication, a necessary step for the development of pluricellular organisms. The fibroblast growth factors (FGF) are among these polypeptides and have seven known members: FGF 1 to FGF 7 which are also known as acidic FGF, basic FGF, translation products of oncogenes hst, int 2, FGF 5, FGF 6 and FGF 7 or keratinocyte growth factor (KGF) respectively [1]. The best known and the most abundant in normal adult tissues are acidic and basic FGFs, or FGF 1 and 2 respectively, which have been subjected to extensive studies both in vitro and in vivo. These two factors have almost ubiquitous distribution and a wide spectrum of biological activity including action on cellular proliferation and differentiation, as well as neurotrophic and angiogenic properties [1]. These different activities are induced by triggering specific receptors present at the surface of the target cell. Following this interaction, the FGF-receptor complexes are internalized and activate intracellular pathways. An important effort of investigations has been produced to characterize these receptors and intracellular pathways. It is the purpose of this review to present this work which will focus on FGFs 1 and 2. The existence of two classes of interactions has been reported as early as 1987 [52, 53, 54] suggesting the presence of high and low affinity receptors for FGFs.

Animals↗
PubMed1992

Cytokine serum level during severe sepsis in human IL-6 as a marker of severity.

Forty critically ill surgical patients with documented infections were studied during their stay in an intensive care unit. Among these patients, 19 developed septic shock and 16 died, 9 of them from septic shock. Interleukin 1 beta (IL-1 beta), tumor necrosis factor (TNF alpha), and interleukin 6 (IL-6) were measured each day and every 1 or 2 hours when septic shock occurred. Although IL-1 beta was never found, TNF alpha was most often observed in the serum at a level under 100 pg/mL except during septic shock. During these acute episodes TNF alpha level reached several hundred pg/mL, but only for a few hours. In contrast, IL-6 was always increased in the serum of acutely ill patients (peak to 500,000 pg/mL). There was a direct correlation between IL-6 peak serum level and TNF alpha peak serum level during septic shock and between IL-6 serum level and temperature or C-reactive protein serum level. Moreover, IL-6 correlated well with APACHE II score, and the mortality rate increased significantly in the group of patients who presented with IL-6 serum level above 1000 pg/mL. Thus, IL-6 appears to be a good marker of severity during bacterial infection.

Adult↗
PubMed1991

Enhanced MYCN oncogene expression in human neuroblastoma cells is associated with altered FGF receptor expression and cellular growth response to basic FGF.

We have examined the effect of human basic fibroblast growth factor (bFGF) on the proliferation of human neuroblastoma cells with normal and enhanced MYCN oncogene expression. bFGF stimulated the proliferation of the neuroblastoma cells with enhanced, but not normal, MYCN expression. Both cell species express FGFR-1, but not FGFR-2, receptors and both harbor FGF receptor species of Mr 145.000, but they differ in their pattern of lower and higher-molecular weight FGF receptor species. Our results demonstrate that enhanced MYCN expression confers to neuroblastoma cells the ability to respond to bFGF, possibly by inducing functional FGF receptors. This mechanism may contribute to the advanced malignant phenotype of human neuroblastomas with enhanced MYCN expression.

Blotting, Northern↗
PubMed1991

High affinity receptors to acidic and basic fibroblast growth factor (FGF) are detected mainly in adult brain membrane preparations but not in liver, kidney, intestine, lung or stomach.

We have previously shown that only adult brain contained a detectable amount of high affinity receptors for basic Fibroblast growth factor (bFGF) whereas adult liver, kidney, lung, intestine or stomach showed only low affinity binding sites. We now have studied and compared the distribution of the receptors for acidic Fibroblast growth factor (aFGF) with that of bFGF receptors in the same tissues. Membrane binding of 125I-aFGF was time dependent, reversible and displaced by an excess of unlabeled aFGF. Scatchard analyses of binding data obtained with all tissue membrane preparations revealed the presence of at least one class of low affinity/high capacity interaction sites characterized by apparent Kd values ranging from 3.9 to 6.9 x 10(-8) M. Interestingly and as for bFGF, high affinity receptors for aFGF could be detected only in adult brain membranes. Cross-linking and Scatchard analyses indicate that this family of interaction was characterized by four molecular species of 175, 125, 95 and 70 kDa and by an apparent Kd value of 1.8 x 10(-10) M. Moreover, cross-competition binding assay revealed that these brain high affinity receptors were common for both acidic and basic FGF. These results suggest that these growth factors may share identical functions mediated by the same receptors highly expressed in the brain. Using a cDNA probe for the Bek form of FGF receptors, we were able to show that all the tissues studied expressed this mRNA (4.5 kb transcript) but probably not in sufficient amounts to account for the number of high affinity receptors that we detected only in the brain.

Animals↗
PubMed1990

Evidence of high and low affinity binding sites for basic fibroblast growth factor in mouse placenta.

The placenta has been shown to contain bFGF, but the presence of specific binding sites for this growth factor in this tissue remained to be established. In order to study the role of bFGF in the placenta growth, we looked for specific binding sites on mouse placental cell membranes at days 12, 14, 16, and 18 of pregnancy. At day 12, Scatchard analyses indicated that two classes of specific interaction sites for bFGF were detected. One class of high affinity binding sites was characterized by an apparent Kd of 10 pM and a binding capacity of 10 fmoles per mg of membrane protein. A second class of low affinity binding sites was detected with an apparent Kd of 60 nM and a binding capacity of 26 pmoles per mg of membrane protein. At days 14, 16 or 18, Scatchard analyses only showed low affinity binding sites with an apparent Kd of 24 nM and a binding capacity of 230 pmoles per mg of membrane protein. The characterization of these binding sites was performed by cross linking experiments that revealed two forms of specific complexes. This result suggested that the high affinity binding sites correspond to putative receptors with relative molecular masses equal to 65,000 and 85,000. The dramatic decrease of the high affinity receptor number after the 12th day of pregnancy, which is synchronous with the 9-fold increase of the low affinity binding site number, suggests that the biological activity of bFGF could be regulated by a balance between both the numbers of high and low affinity binding sites on placenta cell membranes. Thus, as it was shown for other growth factors, bFGF could only be involved at specific pregnancy stages.

Animals↗
PubMed1989

Distribution of basic fibroblast growth factor binding sites in various tissue membrane preparations from adult guinea pig.

In order to localize a rich source of basic FGF receptor, we examined the distribution of basic FGF binding sites in brain, stomach, lung, spleen, kidney, liver and intestine membrane preparations from adult guinea pig. Comparative binding studies using iodinated basic FGF showed that a specific binding was detected in all the membrane preparations tested. Scatchard plots from iodinated basic FGF competition experiment with native basic FGF in various membrane preparations, suggested the presence of one class of binding sites in some tissues such as liver, kidney, spleen, lung, stomach, and intestine with an apparent dissociation constant (appKD) value ranging from 4 to 7.5 nM and the existence of a second class of higher affinity sites in brain membranes with appKD value of 15 pM. Characterization of these basic FGF high affinity interaction sites was performed using a cross-linking reagent. These results show for the first time that specific interaction sites for basic FGF are widely distributed, suggesting that this growth factor might play a role in the physiological functions of a number of adult organs.

Animals↗