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Biomedical subjects

C Evrard

Publications and source records attributed to C Evrard.

At least 37 records · Page 2Linked to original sources
PubMed1998

Escherichia coli and Lactobacillus plantarum responses to osmotic stress.

Escherichia coli and Lactobacillus plantarum were subjected to final water potentials of -5.6 MPa and -11.5 MPa with three solutes: glycerol, sorbitol and NaCl. The water potential decrease was realized either rapidly (osmotic shock) or slowly (20 min) and a difference in cell viability between these conditions was only observed when the solute was NaCl. The cell mortality during osmotic shocks induced by NaCl cannot be explained by a critical volume decrease or by the intensity of the water flow across the cell membrane. When the osmotic stress is realized with NaCl as the solute, in a medium in which osmoregulation cannot take place, the application of a slow decrease in water potential resulted in the significant maintenance of cell viability (about 70-90%) with regard to the corresponding viability observed after a sudden step change to same final water potential (14-40%). This viability difference can be explained by the existence of a critical internal free Na+ concentration.

Cell Size↗
PubMed1998

Proliferation and differentiation properties of permanent Schwann cell lines immortalized with a temperature-sensitive oncogene.

Permanent Schwann cells lines have been established in culture after stable transfection of newborn rat Schwann cells with the pJC-SVLTtsA vector, expressing a thermosensitive oncogene driven by the early promoter-enhancer region of the gliotropic GS/B variant of the papovavirus JC. The proliferation and differentiation of two clonal cell lines have been studied. The cells of these lines display the morphology of primary Schwann cells and express Schwann cell differentiation markers such as the S-100 protein, laminin, the low-affinity receptor to nerve growth factor and the glial fibrillary acidic protein. One of the lines is able to differentiate further. Indeed, in the presence of dorsal root ganglion neurones, the cells synthesize the myelin Po protein and are capable of some myelination, although to a lesser extent than secondary Schwann cells.

Animals↗
PubMed1998

[Cystic lymphangioma of the mediastinum. Apropos of 3 cases, review of the literature].

Cystic hygromas are benign cysts frequently discovered incidentally on chest X ray films. Although CT scan provides helpful information about the size, density, and site of the cysts, it cannot establish a precise diagnosis concerning its nature. Complete removal of the cyst is the treatment of choice, and allows precise diagnosis on histological examination. However, surgical excision is sometimes difficult, due to the size and extension of the cysts, infiltrating mediastinal planes, enveloping great vessels, displacing mediastinal organs without invasion. The difficulty of completely eradicating certain cysts explains cases of insidious progression with compressive recurrence.

Adult↗
PubMed1997

Crystallization and preliminary X-ray analysis of bacteriophage lambda lysozyme in which all tryptophans have been replaced by aza-tryptophans.

After many unsuccessful attempts to crystallize the bacteriophage lambda lysozyme, a mutant where all the tryptophan residues have been replaced by aza-tryptophans has been crystallized by the vapor-diffusion method. The crystals are orthorhombic and belong to space group P2(1)2(1)2(1) with cell dimensions a = 73.01, b = 78.80, c = 82.31 A. Diffraction data were collected using synchrotron radiation sources. Crystals diffract to a resolution of 2.3 A. Data from two different platinum derivatives were also recorded to 2.8 and 2.5 A, respectively.

Journal Article↗
PubMed1997

Purification, molecular cloning, and functional expression of the human nicodinamide-adenine dinucleotide phosphate-regulated thyroid hormone-binding protein.

The kidney and several other thyroid hormone-responsive tissues contain a NADP-regulated thyroid hormone (TH)-binding protein (THBP), with an apparent molecular mass of 36 kDa on SDS-PAGE, responsible for most of the intracellular high-affinity T3 and T4 binding. THBP was purified to homogeneity from human kidney cytosol and used to generate proteolytic peptides. Microsequencing of four peptides revealed identity to amino acid sequences deduced from a human cDNA homolog to a cDNA encoding kangaroo mu-crystallin. This protein is a major structural kangaroo lens protein with no known function in other species. A full-sized cDNA (TH5.9) was isolated by 5'- and 3'-rapid amplification of cDNA ends using a human brain cDNA library and gene-specific PCR primers, confirming identity to the previously cloned human cDNA. The TH5.9 cDNA encodes a 314-residue protein (theoretical mol wt = 33,775) with significant homologies (40 to 60%) with two bacterial enzymes: lysine cyclodeaminase and ornithine cyclodeaminase. The TH5.9 cDNA was expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein. Purified GST fusion protein, but not GST, bound T3 specifically with high affinity [dissociation constant (Kd) = 0.5 nM] in the presence of NADPH, and was labeled by UV-driven cross-linking of underivatized [(125)I]T3. T3 binding and photoaffinity labeling of GST fusion protein were activated by NADPH [activation constant (K[act]) = 10(-8) M], but not by NADH. The expressed protein displays the appropriate binding properties, indicating that TH5.9 cDNA encodes the NADP-regulated THBP characterized in human tissues.

Amino Acid Sequence↗
PubMed1997

[Identification of NPDC-1, gene involved in the control of proliferation and differentiation of neural and glial precursors].

Most of the genes involved in the regulation of proliferation and differentiation of neural cells remain to be identified. With the aim of identifying such genes, the strategy we used was to search for cDNAs which both hybridized with helix-loop-helix degenerated probes and corresponded to RNAs expressed preferentially when neural precursor cells become growth-arrested and began to differentiate. This led to the isolation of NPDC-1 cDNA and then of the genomic sequence. We observed that NPDC-1 is specially expressed in the nervous system and that the transfection of neural precursors with NPDC-1 cDNA results in the inhibition of cell proliferation. Moreover, the stable introduction of NPDC-1 into transformed cells downregulates cell proliferation both by increasing the generation time and by suppressing transformed and tumorigenic properties. We verified that these biological effects were reversed by NPDC-1 anti-sense oligonucleotides. Then we have examined the expression of NPDC-1 mRNA along mouse development and the interactions of the NPDC-1 protein with cell cycle regulatory proteins. The results showed that NPDC-1 mRNA begins to be expressed in a variety of neural structures, when the precursors enter their terminal differentiation. In addition, we have observed that NPDC-1 protein interacts with the transcription factor E2F-1. As a whole, the present results show that NPDC-1 down-regulates the proliferation of neural precursors, is able to suppress oncogenic transformation, is involved in the terminal differentiation of neural cells and acts probably through interactions with E2F-1.

Animals↗
PubMed1996

Relationship between structural properties and affinity for herpes simplex virus type 1 thymidine kinase of bromine substituted 5-heteroaromatic 2'-deoxyuridines.

The crystal structures of 5-(5-furan-2-yl)-2'-deoxyuridine (II), 5-(5-bromofuran-2-yl)-2'-deoxyuridine (IV) and 5-(3-bromothien-2-yl)-2'-deoxyuridine (V) have been studied in order to explain the different affinity of the compounds for the herpes simplex virus type 1 (HSV-1) thymidine kinase. These compounds present a variable affinity according to the position of the heteroatom substituting the five-membered ring. An unfavourable substitution in the five-membered ring for interaction with the HSV-1 thymidine kinase has been identified.

Antiviral Agents↗
PubMed1995

Identification of a neural-specific cDNA, NPDC-1, able to down-regulate cell proliferation and to suppress transformation.

Immortalized neural precursor cell lines carrying the polyoma large tumor (T) gene have been shown previously to retain a clear-cut contact inhibition of growth and to differentiate in vitro. In the present study, we have identified and isolated cDNA clones corresponding to RNA expressed preferentially when these cells reach confluence. One of them, NPDC-1, is expressed specifically in the nervous system. The transfection of dividing cells with a NPDC-1 expression vector results in the inhibition of cell proliferation. In addition, the stable introduction of NPDC-1 into transformed cells, even of nonneural origin, leads to the suppression of transformed characteristics.

Amino Acid Sequence↗
PubMed1995

A permanent glial precursor cell line, immortalized with the adenovirus E1A gene, undergoes apoptosis in restrictive growth conditions.

We have previously described some differentiation properties of the ERD.1.1 cell line, obtained after transfer and integration of the adenovirus-5 E1A gene. Depending on the growth conditions, these cells differentiate towards the astrocyte or early oligodendrocyte differentiation pathway. However, in growth restrictive conditions, we observed dying cells that detached from the monolayer constituted of differentiating cells. This led us to examine the characteristics of the dying cells. The study of the low-molecular-weight DNA and the ultrastructural examination of chromatin showed that these cells were undergoing apoptosis. The results also suggest that the expression of an integrated polyoma middle T gene can partly save the cells from apoptosis.

Adenovirus E1A Proteins↗
PubMed1994

Immortalization of different precursors of glial cells with a targeted and temperature-sensitive oncogene.

Different types of glial precursor cell lines were obtained after stable transfection of brain cells with the pJC-SVLTtsA vector carrying the tsA58 simian virus 40 large T (SVLT) gene driven by the promoter of a gliotropic strain of JC papovavirus. The immortalized cells were conditional for growth: they expressed the SVLT antigen and proliferated at 34 degrees C, but their growth was either reduced or arrested when they were shifted to 39 degrees C. The differentiation characteristics of four representative lines were more extensively studied. The CR15 and CM8 lines displayed properties of bipotential glial progenitors: they were able to express oligodendrocyte markers at both temperatures, but could differentiate into astrocytes only at 39 degrees C. In contrast, the CR19 and CM3r lines corresponded to more committed oligodendrocyte precursors: they expressed various oligodendroglial markers but they could not synthesize the glial fibrillary acidic protein. More particularly, the CM3r mouse cells displayed a typical oligodendrocyte progenitor morphology and expressed the proteolipid protein mRNA.

Animals↗
PubMed1994

Stereoelectronic properties of five anti-HSV-1 2'-deoxynucleosides analogues with heterocyclic substituents in the 5-position: a comparison with BVDU.

Structural and electronic characteristics of 5-(5-chlorothien-2-yl)-2'-deoxyuridine (I), 5-(furan-2-yl)-2'-deoxyuridine (II), 5-(5-bromofuran-2-yl)-2'-deoxyuridine (III), 5-(3-bromoisoxazol-5-yl)-2'-deoxyuridine (V) and 5-(isoxazol-5-yl)-2'-deoxyuridine (IV) have been determined and compared to the BVDU (VI) characteristics in order to explain their respective affinity for the herpes simplex virus type 1 thymidine kinase (TK). Molecular structure of 5-(5-chlorothien-2-yl)-2'-deoxyuridine has been obtained using single crystal X-ray crystallography. Electrostatic potential maps, energy and topology of frontier orbitals were computed at the ab initio MO STO-3G and STO-3G level. These studies reveal that the electrostatic potential energy maps are clearly dependent on the affinity of the compound for the enzyme.

Antiviral Agents↗
PubMed1994

[Extramedullary hematopoiesis of thoracic and vertebral intraductal localization. Apropos of a case. Review of the literature].

The authors report a case of extramedullary haematopoiesis, presenting in the form of several tumor masses in the posterior mediastinum and in the vertebral canal. The patient presented with oedema in his lower limbs due to compression of the inferior vena cava by the mediastinal masses. The asymptomatic mass in the vertebral canal was detected by magnetic resonance imaging. The patient was first operated on to avoid spinal cord compression by the tumor and subsequently to relieve compression of the inferior vena cava. The masses removed from the vertebral canal and the mediastinum were found on histologic examination to be extramedullary haematopoiesis. The cause of the disease was unknown in this case. Such disease is often disclosed in the course of hemolytic anaemias or other medullar deficiency diseases as a compensatory phenomenon when the bone marrow fails. An other explanation is that it is a manifestation of a myeloproliferative disorder in which heterotopic pluripotential cells are transformed into haematopoietic cells. The authors review 88 cases reported in the world literature.

Aged↗
PubMed1993

Proliferation and differentiation properties of bipotent glial progenitor cell lines immortalized with the adenovirus E1A gene.

Bipotent glial progenitors have been immortalized by the transfer of the adenovirus E1A gene into primary cultured cells from embryonic rat brain. The lines obtained are phenotypically untransformed, retain growth contact-inhibition, and are able to differentiate, unless they are surtransfected with transforming oncogenes. Depending on the growth conditions, these immortalized cells express differentially either oligodendrocyte or astrocyte-specific markers and genes. After being seeded in serum-free medium, they display gangliosides recognized by A2B5 monoclonal antibody, and then they express sequentially O4 epitopes, galactocerebroside, and the myelin protein DM20. When grown in serum-supplemented medium, the cells express at first A2B5 epitopes, and then transiently O4 and galactocerebroside; after reaching confluence, O4 and galactocerebroside become undetectable, whereas the cells begin to coexpress glial fibrillary acidic protein and glutamine synthetase. These results indicate that the cell lines can undergo a differentiation reminiscent both of O-2A progenitors and of plastic process-bearing glial subpopulations. The cells were also genetically marked by the stable introduction of the nlslacZ reporter gene. Thus, the lines could be useful for studying direct interactions in vitro, or for post-grafting investigations. They should also provide a model for studying the mechanisms involved in the commitment and in the control of proliferation and differentiation of this cell lineage. This suggestion is consistent with the data indicating a growth arrest-dependent differential expression of a novel gene encoding a protein with a helix-loop-helix domain.

Adenovirus E1A Proteins↗
PubMed1993

[Value of the posterior route in the surgical treatment of popliteal aneurysm].

The authors report about 4 cases of surgical treatment of popliteal aneurysms through a strictly posterior approach. In all cases, the aneurysm was asymptomatic and diagnosed during the assessment of a controlateral symptomatic popliteal aneurysm that was treated in a conventional manner (exclusion and interposition of a femoropopliteal prosthetic tube through a medial approach). The procedure is carried out with the patient in ventral decubitus, and it consists in a debridement and graft with direct anatomical interposition of a straight PTFE tube. The posterior approach has limitations as it does not allow craniad extension and applies only to sacciform or short fusiform aneurysms the upper pole of which does not extend beyond Hunter's canal. The graft was an 8-mm PTFE straight tube in all 4 cases. All patients had a dynamic bilateral control angiography made and none of them presented with symptoms. Three conventional restorations required later embolectomy for thrombosis of the prosthesis. In our opinion, the use of the posterior approach for the surgery of popliteal aneurysm is appealing-provided strict criteria (aneurysm size, scheduled surgery, prosthesis) are complied with--as it reduces morbidity, restores the anatomical course and allows reducing the rate of postoperative thrombosis, thus ensuring better long-term patency.

Aneurysm↗
PubMed1993

[Role of bronchial resection-anastomosis in conservative surgery of lung cancer. Apropos of 34 cases].

We report our 20 year experience with bronchial sleeve resection for endobronchial neoplasms. Among 832 patients who underwent resection procedures, thirty-four underwent a bronchial sleeve resection (4.1%): 27 bronchogenic carcinomas out of 780 (3.5%) and 7 carcinoids tumors out of 52 (13.4%). Bronchial sleeve resection is an appropriate treatment for neoplasms with low grade malignant potential and selected cases of bronchogenic carcinoma (tumor invading the adjacent main-stem bronchus without large hilar extension), especially for patients with compromised pulmonary function. There were no operative deaths; but minor complications occurred in 20% of patients without any major complications. Sleeve resection is a safe and adequate resection therapy for tumors with low-grade malignant potential and for selected cases of carcinoma.

Adolescent↗
PubMed1992

[Impotence of vascular origin. Techniques of exploration and therapeutic orientations].

Vascular problems of arterial and/or venous origin are often found as the cause of erectile dysfunction. Clinical examination alone is insufficient and must followed up by a number of non or minimally invasive tests in order to confirm the etiology. Such testing should include: Doppler measurements or, better, duplex sonography, nocturnal penile plethysmography, psychological status, clinical biochemistry and intracavernous injection of vasoactive drugs. Occasionally, it may be necessary to complete these tests by more invasive examinations: pharmacoarteriography and/or pharmacocavernosography. Several novel therapeutic approaches have been developed in recent years and have given rise to encouraging improvements.

Adult↗
PubMed1991

[Massive hemoptysis ten days after bronchial extraction of an accidentally inhaled tablet of ferrous sulfate].

Fatale haemoptysis occurred as a result of circumferential caustic erosion to the right intermediate bronchus caused by a tablet of ferrous sulphate which remained in contact for 4 days. The necrotic process continued, after removal of the foreign body, in the bronchial wall and its vessels. We suggest local bronchial lavage with 1% bicarbonate saline during extraction of the tablet and subsequent follow-up fibroscopies. The discovery of a necrotic ulceration of the bronchus requires strict medico-surgical surveillance in order to rapidly intervene under cover of selective intubation when necessary.

Accidents, Home↗