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Biomedical subjects

N Girard

Publications and source records attributed to N Girard.

At least 109 records · Page 6Linked to original sources
PubMed1992

Establishment and characterisation of a human glioma cell line.

A new cell line, CB109, has been established from a human glioblastoma multiforme. The cytoskeleton was positive for glial fibrillary acidic protein, vimentin and fibronectin. Hyaluronan (HA) and the HA-binding protein hyaluronectin (HN) were expressed in the cell cytoplasm and in the extracellular matrix of spheroids and plated cells. Hyaluronidase did not prevent spheroid formation suggesting that HA was not involved in the cell-cell adhesion. HA precoating prevented cell adherence to the plates and favoured spheroid formation. HA was secreted in relatively large amounts into the culture medium. High performance liquid chromatography demonstrated that HA was in the high molecular weight form. The rate of HN secretion by cells was very low. Basic fibroblast growth factor significantly increased the proliferation in vitro and tumour growth after grafting into nude mice. The epidermal growth factor receptor was not expressed on cultivated CB109 cells. Cytogenetic analysis showed polysomy 7, structural rearrangement of chromosome 10 short arm and a translocation 13q13-q14 without detectable alteration of the RB gene.

Animals↗
PubMed1992

[Pituitary tumor syndrome and hyperprolactinemia in peripheral hypothyroidism].

We studied 7 women with primary hypothyroidism who were suspected to harbor a prolactinoma on the basis of a pituitary gland enlargement associated with hyperprolactinemia. The diagnosis of prolactinoma was confirmed in 1 case only, which was treated surgically. In the remaining 6 patients the serum prolactin levels fell to normal on thyroxine replacement therapy and reduction in size of the pituitary gland was demonstrated by neuroradiological imaging in the 3 documented cases. This study underlines the fact that hyperprolactinemia associated with pituitary hyperplasia is secondary to hypothyroidism and that thyroid function tests should be obtained in all hyperprolactinemic patients even those with pituitary enlargement.

Adult↗
PubMed1992

[Production of hyaluronan-binding glycoprotein by human monocytes. Its use as marker in myeloid leukemia].

A hyaluronan-binding protein fraction was isolated by affinity chromatography of peripheral human blood mononuclear cell culture medium through immobilized hyaluronan. The presence of a hyaluronan-binding protein similar to human brain hyaluronectin was demonstrated by (i) the ELISA method on hyaluronan-coated plastic plates using anti-hyaluronectin antibodies, (ii) the lowering of the elution volume of the protein on liquid gel chromatography in the presence of hyaluronan, (iii) the extinction of the reaction to human brain hyaluronectin when antibodies were absorbed out with monocyte hyaluronectin, (iv) western blotting with polyclonal and monoclonal anti-hyaluronectin antibodies. The hyaluronectin-producing cells were adherent (10 min., 37 degrees C) to plastic, esterase (+) and CD 14 (+) cells and had the morphology of monocytes. The protein expression was investigated in leukemic cells by means of the immunocytochemical method. Hyaluronectin expression was restricted to 4/12 of M4 and M5 types of acute myeloid leukemias. Other myeloid leukemia and acute lymphoblastic leukemia cells were negative. The results indicate that hyaluronectin can be produced under free form in the absence of hyaluronan, by human peripheral blood monocytes. It supports the hypothesis that the expression of hyaluronectin in tumour stroma could be due, at least in part, to inflammatory cells of the tumour. The expression of the protein by M4 and M5 acute myeloid leukemia cells suggests that hyaluronectin could be synthesized by immature cells of the monocytic lineage as well as by mature monocytes.

Biomarkers, Tumor↗
PubMed1992

[Evaluation of nuclear magnetic resonance imaging in tridimensional acquisition in the investigation of prolactin microadenoma].

Twenty one patients with suspected prolactin-secreting microadenoma were evaluated with MRI. MRI is the most sensitive means for detecting focal microadenomas. In these patients who were clinically and endocrinologically considered to harbor a microadenoma, MR detected a focal pituitary signal abnormality in 100% when the patients had not previously taken bromocriptine therapy. On the other hand MR demonstrated a focal abnormality in only 30% of cases when the patients had been on dopamine agonist therapy: the MRI findings in the group of bromocriptine treated patients are not affected by neither the duration and dosage of the therapy or the delay between MR examination and the bromocriptine therapy discontinuation. Among the 9 cases in which MRI did not demonstrate a focal abnormality, MRI was strictly normal in 3 cases only; MR showed a localized expansion of the subarachnoid space in two cases; the pituitary gland was large and round, and had a homogeneous signal in one case; the pituitary gland had a heterogeneous signal in 3 cases. In our study the microadenoma had a high signal intensity on the precontrast T1 weighted sequence in 5 cases. The focal abnormality was not seen on the precontrast MR images in 2 cases. The microadenoma enhanced in 3 cases on the postcontrast three dimensional MR images. This MR technique allows thin section slices (1 mm) and therefore the detection of small focal abnormality of the pituitary gland (2.5 x 3 mm). Thus three points have to the emphasized: a) MRI always detected a microadenoma when the patients had never received a bromocriptine therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Characterization of a hyaluronic acid-binding protein from sheep brain comparison with human brain hyaluronectin.

1. A hyaluronic acid (HA)-binding glycoprotein from sheep brain was characterized. 2. The specific affinity for HA was shown in vitro by high performance liquid chromatography, polyacrylamide gel electrophoresis and ELISA methods. 3. The KD for high molecular weight HA was 5.4 10(-9) M at 37 degrees C and lower than 10(-10) M at 4 degrees C. 4. No link protein was found and HA molecules could bind up to 10 times their weight of the glycoprotein. 5. The specific site for interaction was the HA-derived decasaccharide HA10. 6. The protein is composed of one polypeptidic chain. Tryptophan and lysine play a prominent role in the conformation of the binding site to HA. 7. Enzyme analysis indicated that the protein different forms are due to differences in glycosylation and that N- and O-linkages coexist in the molecules. 8. Immunohistochemistry localized the glycoprotein at the nodes of Ranvier and at the periphery of neurons. The perineuronal labeling was seen around all neurons studied in the cerebellum whereas it was almost undetectable in the cerebral hemispheres. 9. HA is not saturated by hyaluronectin (HN) in the sheep nervous system. 10. The glycoprotein is largely similar to human brain HN, and different from the hyaluronate-binding protein characterized in the cartilage.

Amino Acid Sequence↗
PubMed1991

MRI study of brain myelination.

Brain development in infants is characterized by growth and myelination. Myelin is a cell membrane devoid of MRI signal; the MRI images obtained at different stages of myelination result from changes in brain tissue water content, from the multiplication of glial cells which precedes myelination (the so-called myelination gliosis), and from the accumulation of lipid myelin precursors contained in cells. T1-weighted sequences are used for the "premyelination" process and T2-weighted sequences for myelination proper. The development of myelination in the white matter is sequential, precisely determined, identical in all individuals, and it has been well studied by histologists. In vivo, myelination in infants is shown at MRI as the same precise sequence but with some changes in time towards the end. The myelination process takes place at different times and different speeds in different brain regions, and for any given structure the speed of myelination varies in relation to time.

Age Factors↗
PubMed1991

[Extrinsic allergic alveolitis. Apropos of a severe case].

A case of atypical extrinsic allergic alveolitis in a 13-year-old is reported. Onset was sudden with gradually increasing dyspnea on exertion over a four-day period. The chest film evidenced a reticulonodular syndrome with decreased respiratory movements. The patient's clinical status worsened over the next 48 hours with the development of respiratory distress. Under oxygen therapy (3 l/min), PO2 was 49 mmHg and SO2 was 82%. Dramatic improvement occurred after initiation of corticosteroid and antimicrobial therapy. Etiologic investigations were negative except for the immunofluorescence test with pigeon droppings which showed three precipitation arcs. A CT scan of the chest disclosed diffuse micronodular densities without thickening of connective tissue trabeculae, suggesting alveolar disease. Mediastinal lymph nodes were not enlarged. Vital capacity was 26% of the theoric value. Corticosteroids were given for one month. On follow-up chest films, the reticulomicronodular syndrome was seen to abate, globally at first, then from the apices to the bases of the lungs. However, a repeat CT scan at the 4th month showed that diffuse lesions were still present although the chest film was normal; 8 months after onset, there was only a bulla in the left lung base, with no evidence of fibrosis. Lung function tests slowly returned to normal, as did CT scan findings.

Adolescent↗
PubMed1990

Immunoreactivity of boronated antibodies.

Boronated antibodies have already been evaluated as agents in neutron capture therapy. Because the boronation procedure may alter the properties of the antibody it is important to study the immunoreactivity of the conjugated antibody before in vivo use. In our studies of two dextran-boronated monoclonal antibodies, anti-glial fibrillary acidic protein antibody, and anti-hyaluronectin antibody, we have used ELISA and immunohistological methods to determine antibody activity and specificity. A ten-fold decrease in activity was observed for both antibodies in ELISA, and non-specific interactions were seen in both immunohistological and ELISA procedures. The boron compound used was shown to be at least partly responsible for these non-specific interactions.

Animals↗
PubMed1990

The extracellular matrix during neural crest formation and migration in rat embryos.

Changes in the distribution of extracellular matrix components have been investigated immunohistochemically during neural crest development in the rat. Inside the ectodermal epithelium basal lamina components are formed resulting in a separation of neurectoderm and epidermal ectoderm. Within the presumptive neural crest area fibronectin, hyaluronan and chondroitin sulphate become apparent. Upon subsequent neural crest migration the basal lamina becomes disrupted. As the neural crest cells take part in mesectoderm formation, fragments of the basal lamina remain attached to their surface, as is demonstrated with antibodies against laminin and collagen type IV. The extracellular matrix is therefore active both in the separation of neuroectoderm from epidermal ectoderm and in mesectoderm formation.

Animals↗
PubMed1990

Concentration of hyaluronectin and anionic glycoconjugates in perineuronal glial cell processes at GABAergic synapses of rat cerebellum.

Hyaluronectin was detected in the rat cerebellum using monospecific polyclonal antibodies at the light and electron microscopic level. The immunoreactivity was associated in the grey matter with glial (astrocytic) cell processes of perineuronal glial sheets but could not be found in glial cell bodies nor in neurons. This molecular specialization of grey matter astrocyte expansions was distinctly expressed at known sites of GABAergic synaptic transmission.

Animals↗
PubMed1990

Wound repair and the potential use of growth factors.

Failure of wounds to heal increases the physical and financial burden of hospitalization and increases the work load for health care professionals. Although careful attention to nutrition (including adequate replacement of vitamins and trace mineral elements), tissue perfusion and oxygenation, and wound dressing and sanitation promote more rapid and complete healing, some wounds respond only slowly or not at all to these conventional treatment modalities. A group of polypeptide growth factors, including epidermal growth factor, platelet-derived growth factor, transforming growth factor beta, and basic fibroblast growth factor, have been found to promote or hasten healing in animal models. This technology is now moving into the clinical arena where its potential for human healing must be evaluated.

Animals↗
PubMed1990

[Gadolinium-DTPA in the study of intracranial tumors in the adult].

Thirty intracranial tumours were explored by MRI, using T1- and T2-weighted sequences, before and after intravenous injection of Gd-DTPA. Two-thirds of the intra-axial tumours were accurately detected on one section plane by MRI without Gd-DTPA, but in one quarter of the cases Gd-DTPA only delineated precisely the tumour. On the other hand, Gd-DTPA failed to detect certain tumours (benign gliomas) or showed only a small part of them (mixed grade gliomas), while they were detected by MRI without contrast injection. However, in such cases Gd-DTPA was useful for the stereotaxic biopsy of the tumour. Gd-DTPA appears of lesser interest in extra-axial tumours. Gd-DTPA is thus valuable for the neuroradiological diagnosis of brain tumours, particularly to evaluate the grade of gliomas and to confirm the diagnosis of recurrent growths.

Adult↗
PubMed1990

[Intra-arterial thrombolytic therapy of lower limb ischemia].

Between 1984 and 1989, 35 patients with recent arterial or graft occlusions have been treated with intra-arterial infusion using sequential association of Urokinase (U.K.) and Lys-Plasminogen. Occlusion was thrombotic in 68.5% of the cases ans embolic in 31.5%, involving 28 native arteries and 7 bypass grafts. The mean duration was 16 days (2 to 90). Continuous infusion of U.K.: 84,000 U.I./H and bolus of Lys-Plasminogen 15 microKatals every 30 minutes were delivered through a catheter embedded into the clot. Intra-venous heparin was always associated. The mean duration of lytic drug infusion was 8 H. Complementary arterial reconstruction by vascular surgery of percutaneous transluminal angioplasty was performed in 23% of the patients. Patients with recent alimentary tract bleeding, hemorragic stroke in the last six months or severe high blood pressures were contra-indicated. Complete lysis was obtained in 23 cases (66%), partial lysis in 7 (20%) and no lysis in 5 (14%). The clinical result was excellent in 24 cases (68.5%), good in 3 (8.5%) and bad in 8 (23%) in which amputation was always necessary. 5 local hematoma (14%) treated by surgery or transfusion and one death (3%) due to neurological complication occurring 24 hours after the end of the procedure were observed. The literature survey has shown that the results of low doses of Streptokinase (S.K.) local infusions were not better, and that higher doses of S.K. or U.K. delivered during a shorter infusion time increased the efficacy of lysis and decreased the rate of hemorragic complications. We have proposed the local thrombolytic treatment to the limb threatening ischemic cases when the traditional medical or surgical techniques where thought to be associated to a high risk of failure or complication. The specific indications are the acute or sub-acute ischemic situation due to atheromatous artery thrombosis, distal or old embolism where the Fogarty catheter is inefficient, and graft thrombosis. Severe acute ischemia with neurologic involvement are not good indications. Local thrombolysis can be successful on arterial occlusion even after one month duration.

Adult↗
PubMed1989

Hyaluronan and hyaluronectin in the nervous system.

Hyaluronan was studied in extracts of the nervous system and in situ. Extraction yielded larger amounts at neutral or alkaline pH. Protease digestion enhanced the quantitative results obtained with an indirect enzyme immunological assay. It was shown that HA extracted from brain at neutral pH was bound to a glycoprotein component (hyaluronectin, HN) which is in part free at acid pH. Although HN is not restricted to nervous tissue it is mainly expressed in the central nervous system of adult mammals. Its main form has a molecular mass of 68 kDa and binds in vitro to HA and to HA-derived oligosaccharides down to HA10 with a Kd in the 10(-8) M range. HA-HN complexes were found in human cerebrospinal fluids. The HA concentration in cerebral tissue decreases from the fetus to the adult, whereas the HN concentration increases. HA is not however saturated by HN and still binds HN in vitro. In the rat HA decreases sharply at Days 10-11 after birth. In the rat embryo HA forms an extracellular component of the migration and proliferation areas of the cerebral cortex. In the adult typical locations were at the nodes of Ranvier and in perineuronal structures. HN was found in the same locations but seemed to be associated with a restricted category of neurons. In the cerebellum HA-HN was found mainly in the grey nuclei, the granular layer and around Purkinje cells. Cell bodies were not stained but in the electron microscope HN was seen in the cytoplasm and plasma membrane of the perisynaptic glial cell processes. A hypothesis has been proposed that HA-HN is involved in neural GABAergic transmission.

Brain↗