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Biomedical subjects

S Lefort

Publications and source records attributed to S Lefort.

At least 19 recordsLinked to original sources
PubMed2003

Clinical course of premature infants intubated in the delivery room, submitted or not to porcine-derived lung surfactant therapy within the first hour of life.

OBJECTIVES: The aim of this study was to perform a comparative analysis of the clinical outcome, gasometric course and ventilatory indices of premature infants with a gestational age of < or = 34 weeks who were intubated in the delivery room, owing to respiratory insufficiency, according to whether or not they were submitted to porcine-derived lung surfactant therapy within the first hour of life. METHODS: The study was randomized and controlled. A total of 75 premature infants were classified into two groups: group A, comprising 35 neonates who were submitted to surfactant within the first hour of life; and group B, comprising 40 neonates who were not submitted to surfactant within the first hour of life. RESULTS: Exogenous surfactant therapy after establishment of respiratory distress syndrome (RDS) was necessary in eight neonates of group A (22.9%) and 31 neonates of group B (77.5%) (p < 0.001). The neonates in group A presented higher levels in relation to group B for the variables: partial pressure of arterial oxygen (PaO2)/fraction of inspired oxygen (FiO2) and PaO2/partial pressure of alveolar oxygen (PAO2), while neonates in group B presented higher levels for FiO2, PAO2 and difference D(A - a)O2 in relation to group A. Weight affected the oxygenation index (OI) parameter, in that neonates with lower weight presented greater values of the OI. CONCLUSIONS: In premature infants with established RDS, the need for exogenous surfactant was lower in the group that received surfactant within the first hour of life. Furthermore, the gasometric parameters and ventilatory indexes presented a better course in the first 24 h of life among premature infants who received exogenous surfactant within the first hour of life, in relation to those who did not.

Biological Products↗
PubMed1999

Soluble CD14 acts as a negative regulator of human T cell activation and function.

T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4+CD8+, CD4+CD8+ and CD4+CD8+ Tcell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-gamma and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IkappaB-alpha. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3+ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.

Biological Transport, Active↗
PubMed1997

Detection and biochemical characteristics of the receptor for complexes of soluble CD14 and bacterial lipopolysaccharide.

Soluble CD14 (sCD14) has been found to bind LPS and mediate LPS activation of several cell types. It has been postulated that sCD14-LPS complexes induce cell responses by interacting with a cell surface structure, which, in turn, triggers cell activation. There has been no biochemical evidence, however, for a direct interaction of sCD14 with a cell surface structure, and the putative receptor has not been identified. To rigorously test this hypothesis, we studied the interaction of human rsCD14 with cells in the absence of serum and in the presence and the absence of LPS. We found 1) there was specific and saturable binding of 125I-sCD14, indicative of a typical receptor-ligand interaction, to several cell types, including endothelial cells, epithelial cells, astrocytes, and human monocytes; 2) specific binding to all the cell types and IL-6 induction in membrane-bound CD14 (mCD14)-negative cells occurred only when both sCD14 and LPS were present; 3) competitive displacement experiments of 125I-sCD14 binding to astrocytes and Scatchard plots revealed a binding of high affinity (Kd = 3.3 +/- 0.4 nM) and approximately 25,000 single class binding sites/cell; 4) the steady state for the association of 125I-sCD14 was obtained after 180-200 min; 5) chemical cross-linking experiments revealed the association of sCD14 with a binding structure of approximately 216 kDa; 6) binding of 125I-sCD14 to CD14-expressing cell transfectants was about 50% lower than that to nontransfected cells. Maximal binding, however, was recovered after removing mCD14, suggesting that the sCD14-LPS receptor may also interact with mCD14. These results provide direct biochemical evidence for the existence of a cell surface signal-mediating binding structure for LPS-bearing sCD14 and suggest that this structure may represent the signaling unit of the postulated multimeric LPS receptor in mCD14-bearing cells.

Animals↗
PubMed1996

Cloning and characterization of a specific interleukin (IL)-13 binding protein structurally related to the IL-5 receptor alpha chain.

Interleukin-13 (IL-13) is a cytokine secreted by activated T lymphocytes that shares many, but not all, biological activities with IL-4. These overlapping activities are probably due to the existence of common receptor components. Two proteins have been described as constituents of the IL-4 receptor, a approximately 140-kDa glycoprotein (IL-4R) and the gamma chain (gammac) of the IL-2 receptor, but neither of these proteins binds IL-13. We have cloned a cDNA encoding an IL-13 binding protein (IL-13R) from the Caki-1 human renal carcinoma cell line. The cloned cDNA encodes a 380-amino acid protein with two consensus patterns characteristic of the hematopoietic cytokine receptor family and a short cytoplasmic tail. The IL-13R shows homology with the IL-5 receptor, and to a lesser extent, with the prolactin receptor. COS-7 cells transfected with the IL-13R cDNA bind IL-13 with high affinity but do not bind IL-4. COS-7 cells co-transfected with the cloned IL-13R cDNA and IL-4R cDNA resulted in the reconstitution of a small number of receptors that recognized both IL-4 and IL-13. Reverse transcription-polymerase chain reaction analysis detected the receptor transcript only in cell lines known to bind IL-13.

Amino Acid Sequence↗
PubMed1996

A case report of Down syndrome and centroblastic lymphoma.

We describe a case of left cervical stage I centroblastic lymphoma in a 29-year old male patient with Down's syndrome due to a (14; 21) Robertsonian translocation. The disease presented as extensive lymph node necrosis leaving rare areas of tumor cells, accounting for the diagnostic difficulties. According to our review of the literature, lymphoma is one of the most common neoplasms in DS patients and may represent the second most common malignancy in this condition, far behind leukemia.

Adult↗
PubMed1996

[Fibrinolysis of deep venous thrombosis on implantable perfusion devices. Apropos of a consecutive series of 57 cases of thrombosis and 32 cases of fibrinolysis].

The main complication of totally implantable venous access devices is deep venous thrombosis on catheter. It may dramatically reduce the already limited venous capacity of patients undergoing chemotherapy and obturate catheters, causing pulmonary embolism or functional disorders. These thromboses usually involve veins of the superior vena cava system where the catheters are implanted. Generally, they occur early, are extensive and often asymptomatic. Doppler ultrasonography is the diagnostic investigation of choice, phlebography being reserved for particular cases or to specify the limits of the thrombus. In a series of 412 vein access devices implanted and systematically monitored by Doppler ultrasonography, we found 57 thromboses (13.8%), 15 partial and 42 complete. The lowest thrombosis rate was observed in the right internal jugular vein (10% vs 20 to 23%, p = 0.006). Thirty-two patients received a systemic fibrinolytic treatment, 16 with streptokinase (SK), five with urokinase (UK), four with tissue plasminogen activator (rt-PA) and seven with SK/UK association. No serious side effects were observed. Sixteen repermeabilizations (50% of fibrinolysis) were obtained. There were no significant differences with respect to the fibrinolytic, the initial characteristics of thrombosis or the patients. Patients without fibrinolysis received 3 weeks of low molecular weight heparin (curative doses) then warfarin. Only one patient was repermeabilized with this treatment (significative difference with fibrinolysis: p = 0.009). Fibrinolysis is indicated in symptomatic thrombosis and/or in cases of extension to the innominate vein or the superior vena cava. Systematic monitoring by Doppler ultrasonography and prophylactic anti-thrombotic treatment are recommended in patients with implantable venous access devices in order to decrease the occurrence of thromboses, to detect asymptomatic patients at an early stage and to increase the effectiveness of fibrinolysis.

Adult↗
PubMed1995

IL-13 and IL-4 share signal transduction elements as well as receptor components in TF-1 cells.

IL-13 and IL-4 are growth factors for the human erythroleukemia cell line TF-1. In these cells both cytokines share overlapping binding sites, but the number of sites for IL-13 is half of that for IL-4. Two monoclonal antibodies against the extracellular domain of the IL-4R alpha chain completely abolish the binding of IL-13, although IL-13 does not bind to this chain. Following receptor triggering, IL-13 and IL-4 induce the phosphorylation of a 170 kDa protein, probably the IL-4-induced phosphotyrosine substrate. In addition the phosphorylation of the 170 kDa protein results in its tight association with phosphatidylinositol-3-kinase.

Antibodies, Monoclonal↗
PubMed1995

Characterization and comparison of the interleukin 13 receptor with the interleukin 4 receptor on several cell types.

We describe here the characterization of the interleukin (IL) 13 receptor and a comparison with the IL-4 receptor on different cell types. Several, but not all, of the IL-4 receptor-positive cells showed specific IL-13 binding, which was always completely displaced by IL-4. In the IL-13 receptor-positive cells, the IL-13 either completely or partially displaced the labeled IL-4. Further characterization of the IL-13 receptor in two cell lines, COS-3 and A431, representative of the groups of complete and partial displacement of IL-4 by IL-13, respectively, showed that the IL-13 binds with high affinity (Kd approximately 300 pM) to both cells and that the number of binding sites is, in COS-3 cells, equivalent to that for IL-4 and, in A431 cells, is smaller than that for IL-4. Cross-linking of labeled IL-13 yielded, on COS-3 cells, two affinity-labeled complexes of 220 and 70 kDa, and on A431 cells, one complex of 70 kDa; labeled IL-4 yielded on both cells the same pattern of three complexes of 220, 145, and 70 kDa. Altogether, these results suggest that the IL-13 receptor may be constituted by a subset of the IL-4 receptor complex associated with at least one additional protein.

Affinity Labels↗
PubMed1993

Primary structure and functional expression of mouse pituitary and human brain corticotrophin releasing factor receptors.

Corticotrophin-releasing factor (CRF) is the principal hypothalamic factor governing the pituitary-adrenal axis, but the wide extra-pituitary distribution of CRF and its receptors suggest a major role for this neuropeptide in the integration of the overall physiological and behavioral responses of an organism to stress. We have cloned a CRF receptor complementary DNA (cDNA) by expression in COS-7 cells of a cDNA library from the AtT20 mouse pituitary tumour cell line. The cloned mouse cDNA was then as a probe to isolate a human CRF receptor cDNA from a human brain cDNA library. The mouse and human cDNAs both encode 415 amino acid proteins that are 97% identical, containing seven putative transmembrane domains characteristic of G protein-coupled receptors. The CRF receptor shows homology with the receptors for growth hormone-releasing factor, vasoactive intestinal peptide, secretin, parathyroid hormone, and calcitonin. COS-7 cells transfected with the mouse CRF receptor cDNA bind radiolabelled ovine CRF with high affinity and respond specifically to CRF by accumulation of intracellular cAMP. A 2.7 kb mRNA coding for the CRF receptor could be detected in AtT20 cells and human cortex tissue. PCR analysis also detected the receptor transcript in human pituitary, brainstem, and testis.

Amino Acid Sequence↗
PubMed1993

Cloning and expression of a complementary DNA encoding a high affinity human neurotensin receptor.

A human neurotensin receptor (hNTR) cDNA was cloned from the colonic adenocarcinoma cell line HT29. The cloned cDNA encodes a putative peptide of 418 amino acids with 7 transmembrane domains. The amino acid sequence of the hNTR is 84% identical to the rat NTR [Neuron, 4 (1990) 847-854]. Transfection of this cDNA into COS cells results in the expression of receptors with pharmacological properties similar to those found with HT29 cells. Northern blot analysis using the hNTR cDNA probe indicated a single transcript of 4 kb in the brain, the small intestine and blood mononuclear cells.

Amino Acid Sequence↗
PubMed1986

Hydrophobic adsorbents for the isolation and purification of biosynthetic human growth hormone from crude fermentation mixtures.

Hydrophobic interaction chromatography was used as the initial step for the concentration and partial purification of biosynthetic human growth hormone (hGH). This molecule was extracted from the culture medium of a transformed monkey kidney cell line by batch adsorption either to Octyl-Sepharose or Phenyl-Sepharose. The adsorbate was decanted and packed into a column for elution. This initial work-up procedure rendered a concentrated hGH solution that was further purified by ion-exchange and gel filtration chromatography. The hGH obtained was homogeneous, based on polyacrylamide gel electrophoresis, N-terminal sequence and fingerprint analysis.

Adsorption↗
PubMed1983

Molecular signals in antigen presentation. I. Effects of interleukin 1 and 2 on radiation-treated antigen-presenting cells in vivo and in vitro.

In order to clarify the nature of the defect in the process of antigen presentation caused by uv radiation, low-density spleen cells were used as a potent APC source in a hapten-specific cytolytic T-cell (Tc) system. It was demonstrated that IA+ weakly adherent low-density spleen cells, when directly coupled with azobenzene arsonate (ABA), led to the activation ABA-specific Tc. When these APC were exposed to uv radiation (12 J/m2/sec) for 30 sec, their ability to lead to Tc activation was markedly inhibited. The defect imposed by uv radiation could be specifically bypassed by the addition of small amounts of homogeneous IL-1 or IL-2. This led to the specific activation of ABA-reactive H-2-restricted Tc. The purified IL-1 was also found to bypass the systemic defect imposed in vivo by external uv radiation of mice. This may indicate a potential therapeutic role for IL-1.

Animals↗
PubMedDate not supplied

The biological activities of gro beta and IL-8 on human neutrophils are overlapping but not identical.

Gro beta and IL-8 are two members of the small induced secreted (SIS) cytokine family (C-X-C subgroup) with proinflammatory activities on neutrophils. In order to assess whether or not the interaction with their receptors results in similar biological actions, we compared the two cytokines in five different bioassays. Gro beta showed similar biological activities as IL-8 in tests of chemotaxis, induction of the respiratory burst, and induction of interleukin 6 (IL-6) production. However, for two other biological activities: augmentation of the expression of CD11b on the cell surface and rapid elevation of the intracellular calcium concentration, maximal effects required 100 times more gro beta than IL-8. Taken together, these results suggest that the stimulation of the IL-8 or gro beta receptor evokes three similar responses, but that only the activation of the IL-8 receptor and not that of gro beta results in elevated CD11b expression and calcium mobilization in human neutrophils.

Antimicrobial Cationic Peptides↗