Biomedical subjects

D Ducassou

Publications and source records attributed to D Ducassou.

At least 37 records · Page 2Linked to original sources

PubMed1996

Functional upregulation of granulocytes labeled with technetium-99m-HMPAO and indium-111-oxinate.

UNLABELLED: Indium-111-oxinate-labeled granulocytes have been used in vivo for several years for the detection of abscesses. Technetium-99-m-hexamethylpropyleneamine oxime (99mTc-HMPAO) labeling has more recently been described. METHODS: The influence of radiolabeling by both radiotracers on adhesion glycoprotein CD11b quantification was studied in quiescent and formyl-methionylleucylphenylalanine (fMLP)-activated neutrophils (PMN). Adhesion was assessed on human umbilical endothelial cells (HUVEC) as well as the repercussion of the granulocyte labeling on HUVEC viability (neutral red) and metabolic activity (MTT). Chemotaxis of PMN was evaluated by measuring migration under agarose with fMLP as chemoattractant. We also measured phagocytosis and the production of hydrogen peroxide induced by staphylococcus aureus. RESULTS: Whereas whole functional integrity is maintained after labeling, most of the functions (CD11b expression, adhesion, HUVEC metabolic activity) are up-regulated while chemotaxis is decreased in the presence of both radiotracers. Indium-111-oxinate induces larger alterations than 99mTc-HMPAO. CONCLUSION: These data were obtained in normal volunteers. In patients, alterations due to the in vitro labeling procedure, in addition to potential functional alterations caused by the underlying pathology, should be taken into account during image interpretation.

Cells, Cultured↗

PubMed1995

[The concept of nuclear physics].

Understanding of the biological effects of radioactivity on living matter requires some basic notions of nuclear physics. The interreactions between living matter and ionising rays, emitted by natural or artificial radioelements, are responsible for such effects. These radioelements are characterised by the period, the nature and the energy of the rays they emit; they constitute the source of radiation whose effects generally depend on their activity.

Isotopes↗

PubMed1995

A human monoclonal antibody obtained from EBV-transformed B cells with specificity for myosin.

We describe the preparation of a stable human lymphoblastoid cell line obtained during ex vivo studies in which peripheral blood lymphocytes of a Glanzmann's thrombasthenia patient were transformed with Epstein-Barr virus. Somatic hybrids secreted an IgM monoclonal antibody (B7) that reacted with the myosin heavy chain of human platelets by immunoblotting. Flow cytometry showed that B7 barely recognized unstimulated intact platelets, but bound abundantly after permeabilization of fixed cells with Triton X-100. The reactivity of the antibody on thin sections of human myocardium and aorta was studied by immunohistochemistry. B7 specifically stained myosin of myocytes, but there was no labelling of aortic smooth muscle cells. The epitope was conserved in cardiac or skeletal myosin prepared from pig or rabbit. Measurement of the dissociation constant in a competitive ELISA showed that B7 bound with high affinity (10(-8) M). Purified Fab fragments retained their ability to bind to myosin, suggesting that B7 may be useful in the imaging of myocardial necrosis after myocardial infarction, myocarditis, cardiac drug toxicosis or graft rejection. This work also shows that EBV transformation of B cells may uncover naturally occurring autoantibodies which under normal circumstances are inhibited by the immune surveillance system.

Adult↗

PubMed1994

An ex vivo original test using radiotracers for evaluating haemocompatibility of tubular biomaterials.

The haemocompatibility of a vascular prosthesis can be estimated as the result of its interaction with blood components. The authors describe an ex vivo canine shunt for evaluating isotopic haemocompatibility in blood-wall interactions. Methods employing radioisotopic tracers can be used to dynamically monitor the adsorption of labelled blood cells and proteins on different biomaterial surfaces. This ex vivo test should enable materials to be assessed for quality according to two thrombogenic criteria: (i) number of adhered platelets mm-2 s-1; (ii) quantity of adsorbed fibrinogen expressed as microgram mm-2 s-1, which would provide the basis for a scale of haemocompatibility.

Animals↗

PubMed1993

Radioimmunodetection of rat and rabbit cartilage using a monoclonal antibody specific to link proteins.

Biodistribution analysis using [125I]Fab-6F3 specific to link proteins from human articular cartilage performed in rats by autoradiography showed a high concentration of radioactivity in all cartilaginous tissues. Preliminary immunoscintigraphic assays were performed in rabbits. Front and side view images of whole animals exhibited high uptake in cartilage tissue of the knee articulation, in the invertebral disk and the humeral head. This fixation was still detected 24 h post-injection, although high washout of radioactivity was observed.

Animals↗

PubMed1993

Heterogeneity of neuropeptide Y immunoreactivity in patients with pheochromocytoma: influence on the diagnostic power of measuring plasma NPY using antisera with different specificities.

The nature of NPY-like immunoreactivity (NPY-LI) was investigated in plasma and tumour tissue of 17 pheochromocytoma patients by HPLC, gel filtration and isoelectric focusing using two radioimmunoassays (RIAs) directed against the C- and N-terminals of NPY respectively. The two RIAs gave similar results in pheochromocytomas: 86% of cases had higher NPY-LI concentrations than those found in normal adrenal glands and NPY-LI behaved like authentic human NPY during gel filtration and HPLC. Assessed by isoelectric focusing, NPY was found to be amidated in seven of nine tumours. Contrary to the findings obtained in tumours, the results of the two RIAs in plasma samples were not always concordant: compared to controls, elevated concentrations of NPY-LI were found in 86% of cases of pheochromocytomas using the C-terminally directed RIA and in 76% of cases using the N-terminally directed RIA. The results of HPLC and gel filtration of NPY-LI in plasma suggested that circulating C- and N-terminal NPY fragments account for the discrepancy between the results of the two RIAs. In conclusion, most pheochromocytomas contain large amounts of NPY-LI that behaved like authentic NPY by chromatographic analysis. On the contrary, circulating NPY-LI in some pheochromocytoma patients is heterogeneous with cleaved products which influence differently the power of the C- and N-terminally directed RIAs for the diagnosis of pheochromocytoma.

Adrenal Gland Neoplasms↗

PubMed1992

Plasma concentration of neuropeptide Y in patients with adrenal hypertension.

The mechanisms of hypertension during primary hyperaldosteronism and Cushing's syndrome are not completely understood. An enhanced vascular sensitivity to noradrenaline has been described in both situations. Neuropeptide Y (NPY) induces direct vasoconstriction and potentiates the action of noradrenaline. Sodium retention and dexamethasone have been shown to increase circulating NPY levels in animals and the expression of NPY in neuroendocrine cells. In order to determine if NPY could be involved in the enhanced vascular sensitivity to noradrenaline associated with adrenocortical hyperactivity, we measured plasma NPY in patients with Cushing's syndrome (n = 26) and primary hyperaldosteronism (n = 15) and compared it with that of hypertensive patients with pheochromocytomas (n = 13) or essential hypertension (n = 51) and with normotensive controls (n = 47). The concentration of NPY-Like immunoreactivity (NPY-Li) (mean +/- S.E.) in controls was 39.6 +/- 3.0 pg/ml. Elevated concentrations were found in 77% of the samples collected from pheochromocytoma patients (1180.4 +/- 394.0 pg/ml). NPY-Li levels in patients with essential hypertension (35.0 +/- 2.6 pg/ml), primary hyperaldosteronism (31.3 +/- 3.9 pg/ml) and Cushing's syndrome (33.1 +/- 4.8 pg/ml) were not different from that of controls. NPY-Li levels in hypertensive and normotensive patients with Cushing's syndrome were similar (38.5 +/- 7.5 vs 24.2 +/- 3.7 pg/ml). No correlation was found between the NPY-Li level and the mean blood pressure at the time of sampling. Our results suggest that NPY is unlikely to be involved in the pathogenesis of hypertension associated with primary hyperaldosteronism and Cushing's syndrome.

Adolescent↗

PubMed1992

The effect of sodium cromoglycate on platelets: an in vivo and in vitro approach.

Platelet functions are altered in patients suffering from atopic diseases, including asthma. Such alterations might be related to IgE since platelets bear a specific IgE receptor termed Fc epsilon receptor II, and there is some evidence that IgE alone, that is, in the absence of antigen, could modify platelet functions, such as monoamine uptake. Although disodium cromoglycate (DSCG) has been demonstrated to interfere with IgE-mediated activation of human platelets, its effect in the absence of antigen remains unknown. We examined the DSCG effect on IgE-induced alterations both in vivo and in vitro. The effect, in vivo, of a daily intake of 40 mg of DSCG for 4 weeks was assessed on platelet kinetics, studied by a labeling technique on four patients with stable asthma. The effect, in vitro, of DSCG was assessed on IgE-induced alteration in monoamine uptake in platelets from 12 healthy subjects. DSCG significantly increased, in vivo, the mean time constant of platelet-survival curves from 234 +/- 40 to 463 +/- 150 hours (p less than 0.01). The amplitude of this effect increased with the patient's serum IgE concentration. DSCG, in vitro, reduced the inhibitory effect of IgE on monoamine uptake by 82%. This effect was concentration dependent and not related to IgE binding. It is concluded that DSCG alters both the survival time of platelets from allergic patients in vivo and the IgE-dependent monoamine uptake in platelets from normal subjects in vitro. These effects are likely to be related to the direct action of DSCG on cells bearing the Fc epsilon receptor II and might be independent of the specific trigger.

Adult↗

PubMed1992

A new biodegradable elastin-fibrin material; its use in urological, digestive and cardiovascular surgery.

A new original artificial connective matrix mainly made of elastin and fibrin-like product is used to reinforce damaged tissues and to close and restore a loss of substance in several domains of surgery: all sites in the digestive system and urinary tract; besides, it can substitute for the pericardium in iterative heart operations. In all cases, the original tissue is restored ad integrum while the biodegradable material disappears completely, without any complications.

Animals↗

PubMed1992

Experimental evaluation of a collagen-coated vicryl mesh as a dural substitute.

Dural substitutes must provide immediate restitution of a membranous covering for the brain without inducing any adverse reaction in the host or provoking adhesions to underlying nervous tissues. Ideally, the material should disappear completely and be replaced by tissues similar to the dura mater. In this study, parietal dural defects were created in 12 beagle dogs and closed with a vicryl mesh prosthesis made watertight by a film of bovine collagen. Clinical and biological tolerances were satisfactory. There was one case of early local infection. Gross and microscopic examinations performed between 7 days and 9 months after implantation showed degradation of the prosthetic mesh and connective tissue growth into the implant mimicking dura mater as early as 15 days after implantation. There was no attendant inflammatory reaction or cortical adhesions or other adverse reactions. The authors conclude that collagen-embedded vicryl mesh provides satisfactory biological function and compatibility when used as a substitute for dura mater in the dog.

Animals↗

PubMed1992

Comparative value of plasma ACTH and beta-endorphin measurement with three different commercial kits for the etiological diagnosis of ACTH-dependent Cushing's syndrome.

Recent reports suggest that, contrary to radioimmunoassays (RIA), immunoradiometric assays (IRMA) artifactually decrease plasma ACTH levels in patients with the ectopic ACTH syndrome. Discrepancies between RIA and IRMA results may provide a means of discriminating this entity from Cushing's disease. We have compared the results of these two techniques, together with those of a beta-endorphin assay, in 17 patients with Cushing's disease, 9 with the ectopic ACTH syndrome and 30 controls. ACTH-RIA and ACTH-IRMA levels in patients with Cushing's disease were similar (17.5 +/- 2.5 vs 15.1 +/- 2.8 pmol/l) and were correlated (rs = 0.59, p less than 0.01). ACTH-RIA levels in patients with the ectopic ACTH syndrome were higher than ACTH-IRMA levels (27.3 +/- 2.9 vs 14.5 +/- 2.5, p less than 0.01) and these did not correlate. The ACTH-RIA and ACTH-RIA/ACTH-IRMA ratio levels in patients with the ectopic ACTH syndrome were higher than those of patients with Cushing's disease (p less than 0.01), but they overlapped with these in 27 and 31% of cases respectively. Plasma beta-endorphin level was higher in patients with the ectopic ACTH syndrome than in patients with Cushing's disease (81.9 +/- 19.4 vs 26.4 +/- 5.6 pmol/l, p less than 0.01) and was correlated with ACTH only in patients with Cushing's disease. The overlap in beta-endorphin and beta-endorphin/ACTH-IRMA molar ratio levels between the two groups were 19 and 27% respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1992

Multihormonal response to corticotropin-releasing hormone in inferior petrosal sinus blood of one patient with Cushing's disease: comparison with in vitro secretion of the tumoral corticotropes.

A multihormonal response to CRH during inferior petrosal sinus sampling in patients with Cushing's disease has recently been described. Whether it reflects multihormonal secretion by the corticotropic adenoma, or secretion by non-tumorous adjacent cells via paracrine mechanisms remains debatable. We have compared the effect of CRH on ACTH, GH, PRL and TSH secretion during inferior petrosal sinus sampling with its effect on the in vitro secretion of the corticotropic adenoma after excision in one case of Cushing's disease. Before CRH injection in vivo results show significant central-peripheral gradients for all hormones but only ACTH lateralized to the side of the tumor. After CRH administration, the petrosal concentrations of all hormones increased preferentially on the side of the adenoma resulting in significant intersinus gradients: 8.1 for ACTH, 2.0 for GH, 1.8 for PRL and 1.5 for TSH. In vitro results: the adenoma cells were immunostainable for ACTH only. In culture, they secreted ACTH only. Addition of CRH to the culture induced a mean increase of 160% in ACTH secretion but GH, PRL and TSH remained undetectable. Our results favor the hypothesis that the multihormonal response to CRH seen during inferior petrosal sinus sampling in Cushing's disease reflects a paracrine stimulation of the adjacent non-tumorous pituitary cells by the corticotropic adenoma.

Adenoma↗

PubMed1992

[Bone risk of hormone-suppressing therapy in differentiated thyroid epithelioma. Study by dual photon absorptiometry].

A decreased bone mineral density is a well known complication of thyrotoxicosis. If bone is also adversely affected by a subclinical hyperthyroidism is still debated. Such a situation is deliberately induced for treatment of thyroid differentiated carcinoma. We compared bone mineral measurements in case of thyroid carcinoma exposed to prolonged suppressive hormonal treatment (288 patient year, LT3 in 87%) and in age and weight matched controls. We did not find any difference in both sexes between the two populations in term of fracture rate and vertebral mineral density measured by dual photon absorptiometry, nor any influence of gonadal status in women.

Absorptiometry, Photon↗

PubMed1991

[Macronodule associated with bilateral adrenal hyperplasia. A rare misleading cause of primary aldosteronism (two cases)].

Aldosterone-producing adrenal adenoma and bilateral hyperplasia are the two predominant subtypes of primary aldosteronism. Their recognition is based essentially on adrenal CT scan and on measurements of plasma aldosterone and 18-hydroxycorticosterone (18-OHB) concentrations in response to postural testing. We report 2 cases of primary aldosteronism associated with a unilateral hyperplastic macronodule resembling an aldosterone-producing adenoma on CT scan. Plasma aldosterone and 18-OHB concentrations were consistent with this diagnosis in one patient. In the light of these two cases and of those previously published, the investigations needed for the etiological diagnosis of primary aldosteronism are discussed.

18-Hydroxycorticosterone↗

PubMed1991

In vitro association of type III collagen with elastin and with its solubilized peptides.

Elastin fibres or elastin solubilized peptides associated with type III collagen, under physiological conditions, to form a gel-like substance. The gel cohesion could be markedly improved either by desiccation process (gently air-dried rather than lyophilized) or by addition of adhesive connective proteins such as fibronectin, laminin and type IV collagen. They conferred to the material the composition and the structural appearance of typical basement membrane-like structure. Their properties enable us to investigate the biomaterial in several domains.

Adhesiveness↗

PubMed1991

Microencapsulation of isolated pituitary cells by polyacrylamide microlatex coagulation on agarose beads.

Microlatex beads of homogenous size were made by polymerization of a mixture of acrylamide/bisacrylamide dispersed in a microemulsion. The microlatex was aggregated by dilution of the microemulsion in acrylamide solutions. The aggregates were then coagulated by polymerization at the interfaces of agarose beads circulating in a capillary tube containing paraffin oil. Biocompatibility was tested on isolated pituitary cells microencapsulated by this procedure.

Acrylamide↗

PubMed1991

The inhibitory effect of immunoglobulin E on monoamine uptake in human platelets.

The uptake of the monoamine radiolabelled tracer 125I-meta-iodo-benzyl-guanidine (MIBG) was studied in vitro in platelets from 15 healthy volunteers and five allergic patients whose serum IgE concentration was 37 +/- 33 and 650 +/- 200 IU/ml, respectively. The MIBG uptake was determined by means of a gamma counter after incubation in a buffer. Binding of IgE to platelets significantly reduced MIBG uptake both in healthy subjects and in allergic patients. This reduction was significantly related to the action of IgE as it did not occur after binding of IgG. Moreover, MIBG uptake plotted versus increasing concentration of IgE (ranging from 10 to 3000 IU/ml) was fitted by a classical sigmoidal curve which was not significantly different between healthy subjects and allergic patients. Lastly, the effect of IgE on MIBG uptake was due to the binding of the sole IgE as it was not modified by subsequent addition of anti-IgE. It is concluded that the binding of the sole IgE to its specific receptor on platelets alters the transport of monoamines.

3-Iodobenzylguanidine↗

PubMed1991

In vitro evaluation of an epoxy resin's cytocompatibility using cell lines and human differentiated cells.

The cytocompatibility of a polyepoxy resin (Elf Aquitaine) has been studied using both cell lines and human differentiated cell cultures. The human models were gingival fibroblasts and bone osteoblasts, while the cell lines were Hela cells and 3T3 Balb/c cells. Basal cytocompatibility was assessed by estimation of the cell proliferation, total cell protein content, cell membrane sub-lysis, and cell attachment and spreading. Specific cytocompatibility concerning human osteoblasts, from both alveolar and trabecular bone, was determined by measuring the intracellular alkaline phosphatase activity. Resin colonization by the cells was studied by both TEM and SEM. The behaviour of the two cell lines reveals a significant level of discrepancy, whereas the behaviour of human cells, whatever the model, is comparable; however, osteoblasts look more sensitive. Moreover, the results show that this epoxy resin exhibits a moderate cytocompatibility which could be the result of the cytotoxicity of early released products, associated with the considerable surface roughness.

Alkaline Phosphatase↗