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Biomedical subjects

G Lemaître

Publications and source records attributed to G Lemaître.

18 recordsLinked to original sources
PubMed2000

A 1.5-Mb physical map of the hidrotic ectodermal dysplasia (Clouston syndrome) gene region on human chromosome 13q11.

The HED (hidrotic ectodermal dysplasia) or Clouston syndrome gene (named ED2) has been mapped to the pericentromeric region of chromosome 13 (13q11) to a 2.4-cM interval flanked by markers D13S1828 and D13S1830. We have developed a BAC/PAC-based contig map of this region. This contig, comprising 23 clones and spanning 1.5 Mb, was established by mapping of 27 BAC/PAC end-derived STSs, 11 known polymorphic markers, 2 previously mapped genes, and 14 ESTs. The genomic clone overlaps were confirmed by restriction fragment fingerprint analysis. This contig provides the basis for genomic sequencing and gene identification in the ED2 critical region. Of the 14 ESTs mapped to the contig, 6 show homology to human genes and 8 appear to be novel. Expression patterns of the genes/ESTs were tested by Northern blot and RT-PCR. Full characterization of some of these genes, as well as the novel ESTs, will be useful in assessing their involvement in the HED/Clouston syndrome.

Chromosomes, Human, Pair 13↗
PubMed1999

Glycosaminoglycans promote HARP/PTN dimerization.

Heparin affin regulatory peptide (HARP), also called pleiotrophin (PTN), is a secreted polypeptide which binds to heparin and plays a key role in cellular growth and differentiation. In order to assess the determinants potentially important to its biological activity, we tested the ability of HARP to oligomerize, a process involved in mitogenic activity of the heparin-binding fibroblast growth factor. Using dissuccinimidyl suberate cross-linking experiments and affinity chromatography, we report that human HARP forms noncovalent dimers. Dimerization is dependent on the presence of heparin or other sulfated glycosaminoglycans, as chlorate treatment of cells inhibits this process. In vitro, different glycosaminoglycans, such as dermatan sulfate and chondroitin sulfate-C, also induce a dimer assembly of HARP. The relevance of this process was supported by experiments demonstrating that HARP is secreted as a dimer in conditioned medium of NIH-3T3 cells that overexpressed this growth factor and is also associated to the cell surface or to the extracellular matrix.

3T3 Cells↗
PubMed1999

Identification and characterization of an intracellular protein complex that binds fibroblast growth factor-2 in bovine brain.

The fibroblast growth factor (FGF) family is composed of polypeptides with sequence identity which signal through transmembrane tyrosine kinase receptors. We report here the purification from bovine brain microsomes of an FGF-2-binding complex composed of three proteins of apparent molecular masses 150 kDa, 79 kDa and 46 kDa. Only the 150 kDa and 79 kDa proteins bound FGF-2 in cross-linking and ligand-blotting experiments. Binding of FGF-2 to p79 is enhanced in the presence of calcium. Peptide sequences allowed the identification of p150 and the cloning of the cDNAs encoding p79 and p46. The deduced amino acid sequence of p79 reveals high similarity to those of gastrin-binding protein and mitochondrial enoyl-CoA hydratase/hydroxyacyl-CoA dehydrogenase. p46 is similar to mitochondrial ketoacyl-CoA thiolase. Stable transfection of FR3T3 rat fibroblast cells with p79 cDNA analysed by electron microscopy following immunolabelling of ultra-thin cryosections revealed a localization of p79 in the secretory pathway, mainly in the endoplasmic reticulum and the Golgi region, where it is specifically associated with the molecular chaperone calnexin. In vivo a protein similar to the Golgi protein MG-160 forms a complex with FGF-2 and p79.

Acetyl-CoA C-Acyltransferase↗
PubMed1999

Fibroblast growth factor receptors participate in the control of mitogen-activated protein kinase activity during nerve growth factor-induced neuronal differentiation of PC12 cells.

The current paradigm for the role of nerve growth factor (NGF) or FGF-2 in the differentiation of neuronal cells implies their binding to specific receptors and activation of kinase cascades leading to the expression of differentiation specific genes. We examined herein the hypothesis that FGF receptors (FGFRs) are involved in NGF-induced neuritogenesis of pheochromocytoma-derived PC12 cells. We demonstrate that in PC12 cells, FGFR expression and activity are modulated upon NGF treatment and that a dominant negative FGFR-2 reduces NGF-induced neuritogenesis. Moreover, FGF-2 expression is modulated by NGF, and FGF-2 is detected at the cell surface. Oligonucleotides that specifically inhibit FGF-2 binding to its receptors are able to significantly reduce NGF-induced neurite outgrowth. Finally, the duration of mitogen-activated protein kinase (MAPK) activity upon FGF or NGF stimulation is shortened in FGFR-2 dominant negative cells through inactivation of signaling from the receptor to the Ras/MAPK pathway. In conclusion, these results demonstrate that FGFR activation is involved in neuritogenesis induced by NGF where it contributes to a sustained MAPK activity in response to NGF.

Animals↗
PubMed1995

Production and purification of active FGF2 via recombinant fusion protein.

Basic fibroblast growth factor (FGF2) is involved in both cell proliferation and differentiation processes. Heparin may interfere in the stability and biological activities of FGFs. However, it is difficult to obtain FGF preparation without traces of heparin since heparin affinity chromatographies are routinely used to prepare this growth factor. We have therefore devised a means of production of active recombinant FGF2 devoid of heparin traces. The bovine FGF2 gene was inserted into the pMAL-c prokaryotic expression vector and the recombinant protein was synthesised as a fusion product between the maltose binding protein (MBP) and FGF2. Purification of the FGF2 fusion protein was performed by an amylose affinity chromatography. Yields were similar to those obtained by using a traditional heparin affinity column purification procedure. The fusion protein (MBP-FGF2) and the cleaved-off FGF2 were tested for some of their biological properties and compared to recombinant FGF2 purified by heparin affinity chromatography. Mitogenic activity on Chinese hamster lung fibroblasts (CCL39) and neurite outgrowth on pheochromocytoma culture cells (PC12) were used as biological assays. The cleaved-off FGF2 was as active as commercially available recombinant FGF2 (ED50 at 0.16 and 0.04 nM respectively). However MBP-FGF2 was less active (ED50 at 0.9 nM) in both tests.

Amylose↗
PubMed1985

[Multilocular cyst of the kidney. Characteristics of the imaging appearance].

Investigations in a patient with a multilocular cyst of kidney included urography, ultrasonography and computed tomography. Urography images showed a mass occupying the lower half of the left kidney with a lacunar image of pelvis, the association of these two elements suggesting a possible cancer of kidney. Ultrasound and computed tomography imaging demonstrated the fluid nature of the mass with absent partitioning. Findings were compared with data from the pathologic specimen which showed a main unilocular cyst with multiple satellite smaller cysts and a thick intrapyelic formation composed of microcystic aggregates. Pre-operative diagnosis of multilocular cyst was assisted by the use of modern imaging techniques: ultrasound and CT scan, which demonstrated a partitioned renal cystic lesion. Diagnosis is still difficult in atypical forms, however, and the relative frequency of an intrapyelic cyst protrusion is emphasized.

Aged↗
PubMed1983

[Place of computed tomography in the diagnosis and assessment of the spread of malignant kidney tumors].

The value of computed tomography was assessed in 52 patients with malignant kidney tumors, of whom 34 had undergone nephrectomy. Findings on the CT scan in a small group of 9 patients, when it was employed mainly for diagnostic purposes, gave true results in 7 cases, its contribution being decisive in 3 of these 7 cases. Scanning replaced arteriography for evaluation of tumor spread in 40 patients, where it was found to be very effective for assessment of perirenal, pararenal and lymph node extension. A high percentage of doubtful results were obtained during the first few years of use of the CT scan for determining state of veins (renal vein and inferior vena cava). Subsequent refinements in technique markedly improved the incidence of positive results. Computed tomography should be employed as the method of first choice for determining the stage of malignant kidney tumors.

Aged↗
PubMed1982

[Echographic aspects of intestinal invagination].

Two cases of intestinal invagination were investigated by ultrasonography. The image in the first case was related to the palpable abdominal mass, suggesting a digestive tract lesion. In the second case, direct visualization of the invaginated but in the intestinal lamen appears to be a specific image which has not been reported previously.

Adult↗
PubMed1981

[Anterograde pyelography to assess morphology (author's transl)].

The use of anterograde pyelography to assess morphological changes revealed the presence of obstruction in the upper urinary tract, previously undetected by urography, in 61 patients studied. The technique, used almost exclusively to expose the pelvis over the last year, is described. Only in very rare cases was there a failure to puncture the renal pelvis, and no complications occurred. The relative indication of anterograde and retrograde pyelography are discussed, as well as the morphological data obtained by each method in different types of obstruction: complete, severe incomplete, and partial. The main indications for this procedure are reviewed as a function of the etiology.

Adult↗