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Biomedical subjects

R Gilles

Publications and source records attributed to R Gilles.

At least 19 recordsLinked to original sources
PubMed1992

Imaging in the follow-up of soft tissue tumors.

Local recurrences of aggressive soft tissue tumors are frequent and very difficult to detect clinically after surgery and radiation therapy. Ultrasound is limited because the skin is thick. On contrast-enhanced CT, both scars and recurrences increase their signal. MRI is the best technique, and the only one we presently use in the detection of recurrent tumors. We are reporting 511 follow-up examinations in 182 patients after tumor removal. All patients had histologic confirmation or at least 6 months follow-up. There were 164 malignant tumors and 18 cases of aggressive fibromatosis.

Contrast Media↗
PubMed1991

Volume regulation in rat pheochromocytoma cultured cells submitted to hypoosmotic conditions.

The mechanisms at work in cell volume regulation have been studied in PC12 cultured cells. Results show, for the first time to our knowledge, that the volume readjustment process occurring after application of a hypoosmotic saline is sensitive to amiloride, IBMX and forskoline. The process is also inhibited by quinine hydrochloride and trifluoperazine. Volume readjustment is concomtant with a decrease in K+ and Cl- intracellular levels. The decrease in K+ level can be related to an assymetrical change in the fluxes in and out of the ion as shown by flux kinetics studies using Rb86. These results are interpreted considering that the control of the activity of the ion channel pathways associated with volume readjustment in PC12 cells may implicate the Ca(2+)-calmodulin - cAMP system.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Comparative studies of volume restoration following cold-stress induced swelling in renal tissues--I. Effects of ouabain, K+ free medium, colchicine and cytochalasin B on rat and rabbit kidney cortex slices.

1. Cold-stress-induced swelling in rabbit and rat kidney cortex slices cannot be due to the sole inhibition of a Na+/K+ exchange system. In these tissues indeed, ouabain induces no swelling and an exchange of Na+ for K+ or a l/l basis. Inhibition of K+ extrusion at low temperature has also to be taken into consideration. 2. Volume restoration at 27 degrees C after cold-stress-induced swelling is inhibited by ouabain in rabbit slices, not in rat ones. The inhibition in rabbit slices is concomitant with an increase in Na+ at levels higher than equilibrium with the external medium. 3. Volume restoration does not seem to implicate colchicine or cytochalasin B sensitive processes.

Animals↗
PubMed1990

Comparative studies of volume restoration following cold-stress induced swelling in renal tissues--II. Effects of furosemide, amiloride and K+ permeability in rabbit cortex slices.

1. Inhibition of volume restoration by ouabain in rabbit kidney cortex slices is related to an increase in Na+ concentration which may reach levels higher than equilibrium with the external medium. 2. The uphill accumulation of Na+ is not sensitive to amiloride and furosemide. It is dependent on the level of K+ in the external medium. 3. Bringing the slices from cold to normal temperature induces a large increase in Rb86 efflux. 4. It is concluded that the Na+ entry inhibiting volume restoration is driven by an increase in K+ expel occurring upon tissue rewarming.

Amiloride↗
PubMed1990

[Effect of long-term administration of vasodilators and "antitrophic" agents on the structure and function of the heart in hypertensive rats].

In this study, we determined whether the persistency of cardiac hypertrophy after chronic vasodilation therapy with minoxidil (minox) was associated with functional or metabolic alterations in hypertensive rat hearts before, during and after an ischemic insult. In addition, we investigated the effects of the simultaneous administration of difluoromethylornithine (dfmo), a substance that could block hypertrophy by a direct inhibition of protein synthesis. Four groups of male Wistar rats were prepared: 1) normotensive controls (n = 8), 2) untreated renovascular hypertensive rats (HT, n = 15), 3) hypertensives treated with minox (8 mg/kg, n = 19), 4) hypertensives treated with minox and dfmo (1.7 g/kg, n = 20). After 21 days of treatment, the animals were sacrificed. In a small number of hearts, ornithine decarboxylase (ODC) activity was assayed in order to verify that dfmo, which is a suicide inhibitor of ODC, had effectively interrupted the polyamines pathway. The other hearts were prepared for retrograde perfusion at 35 degrees C and at constant flow (10 ml/min x g). Cardiac function was monitored via the balloon inserted in the left ventricle (LV) and the following protocol was applied: a) baseline period (24 min), b) ischemia (24 min), c) recovery (36 min). Finally, the hearts were weighed and LV wall thickness and inner radius were measured. Blood pressure was maintained near normotension in the two treated groups. Mean systolic pressure (in mmHg) was 145 +/- 4 with minox and 144 +/- 3 with minox + dfmo versus 181 +/- 4 in the HT group (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Glycine and other amino compounds prevent chromatin precipitation at physiological ionic strength.

Glycine, proline and taurine, when present in the range 0.1-0.60 M, inhibit chromatin precipitation by sodium chloride. Histone gel electrophoresis revealed that the linker histones H1 and H5 were largely depleted from the supernatant chromatin fraction at 0.2 M NaCl, while this depletion was absent in the presence of glycine. These observations are discussed in relation with the various factors which may be involved in the precipitation process.

Adrenal Gland Neoplasms↗
PubMed1988

Measurement of 3':5'cyclic AMP in biological samples using a specific monoclonal antibody.

A fast and sensitive radioimmunoassay for 3':5'cyclic AMP based on a monoclonal antibody has been worked out. Mice were immunized with protein-conjugated 2'-O-succinyl-3':5'-cyclic AMP. The monoclonal antibody detects 0.1 and 1 pmole cAMP with succinyl cAMP (125I)iodotyrosine methyl ester and (3H) cAMP, respectively, as tracers. It shows no cross-reactivity to other adenosine nucleotides up to the millimolar range; cGMP interferes only if present at a 500 fold excess. Plant and animal tissue samples as well as adenylate cyclase activity were analysed directly or after appropriate purification in case of interfering substances. Cyclic AMP levels measured in various tissues by the antibody binding assay correspond to those obtained by HPLC determination using fluorescent etheno-cAMP.

Adenylyl Cyclases↗
PubMed1988

Relations between cell volume control, microfilaments and microtubules networks in T2 and PC12 cultured cells.

The possible relations between cell volume, microfilaments and microtubules networks have been studied in cultured mice fibrosarcoma cells of line T2 and rat pheochromocytoma cells of line PC12. The obtained results show that: 1. Changes in volume induced by application of hypo-osmotic medium are concomitant with a modification in the organization of the microfilaments network as visualized by immunocytochemistry. The microtubules lattice is not affected in these conditions. 2. Disruption of the microfilaments network by cytochalasin B causes a significant decrease in cell volume in isosmotic conditions. It also deeply affects the volume regulation response of cells swollen in hypo-osmotic media. 3. Disruption of the microtubules lattice by colchicine has no effect on volume in isosmotic conditions nor on the volume regulation that follows application of hypo-osmotic shock. The possible role of microfilaments in cell volume control is discussed.

Actin Cytoskeleton↗
PubMed1985

Cyclic AMP as an intraspheroidal differentiation signal in Volvox carteri.

The action of the macromolecular inducer glycoprotein on sexual reproduction in the green alga Volvox carteri can be modified by altering the external (intraspheroidal) cAMP concentration. Direct proof for the presence of cAMP in the spheroids is given. Protein binding assay and HPLC-fluorimetric analysis independently demonstrate the existence of cAMP in the matrix, cells, and culture medium. Its concentration is higher in sexual cultures, pointing to a transmitting function in sex induction. The presence in the matrix of other members of a protein phosphorylation system suggests an induction-specific signal cascade in this plant.

Cell Differentiation↗
PubMed1985

Effects of osmotic shocks on the ultrastructure of different tissues and cell types.

This study deals with the effects of hyper- and hypo-osmotic media on the ultrastructure of four different types of cells and tissues: rat pheochromocytoma cells of line PC12, mouse Ehrlich ascites tumor cells, rat kidney cortex and intestine. Application of hyper-osmotic conditions induces in the nuclear compartment of the tested cell types a condensation of chromatin, a ruffling of the nuclear envelope with loosening of condensed chromatin from the lamina, and an apparent loss of nucleolar fibrillar component which disappears in a background of diffuse granular material. In hypo-osmotic media, there is a marked decondensation of chromatin and a fragmentation of the granular material of the nucleolus. As far as the cytoplasmic compartment is concerned, the electron density of the cytosol is markedly increasing when going from hypo- to hyper-osmotic conditions and there is no vacuolization in hypo-osmotic media. In kidney cortex slices, application of hypo-osmotic shocks further results in a marked reduction of the extracellular space delimited by the infoldings of the tubular cells plasma membranes. These modifications are discussed in relation to the volume regulation process and the changes in ion concentration that occur in cells submitted to anisosmotic media.

Animals↗
PubMed1979

[Constrictive pericarditis and rheumatoid arthritis].

Pericarditis is the commonest cardiac manifestation of rhumatoid arthritis. It is often clinically latent but it may evolve to constriction or less often to tamponade. The case presented is of a 60 year-old woman with a 5 year history of seropositive nodular rhumatoid arthritis in whom bilateral pleural effusions and constrictive pericarditis were observed after sudden termination of corticotherapy. She was treated successfully by pericardectomy. This complication is far from being exceptional (55 cases already reported). It justifies a systematic search for pericarditis in rhumatoid arthritis, especially by echocardiography.

Arthritis, Rheumatoid↗
PubMed1978

Effects of high hydrostatic pressures on the activity of the membrane ATPases of some organs implicated in hydromineral regulation.

1. The effects of high hydrostatic pressures have been studied on the ATPases extracted from tissues implicated in iono- and osmoregulation of a frog and various teleostean fishes. Pressure affects enzyme activity in the same qualitative way, whatever the tissue and the species considered. 2. The Mg2+ ATPase activity is maximally enhanced at 250 kg/cm2. A slight inhibition is observed at higher pressures up to 1000 kg/cm2. 3. The (Na+ + K+)ATPase is little affected by low pressures but strongly inhibited at 500 kg/cm2 and more. 4. The results are discussed in terms of pressure effects on the recently described protein-lipid interaction linked to ATPase activity.

Adenosine Triphosphatases↗