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M Cogneau

Publications and source records attributed to M Cogneau.

31 records · Page 2Linked to original sources
PubMed1988

In vivo measurement of carbon-11 thymidine uptake in non-Hodgkin's lymphoma using positron emission tomography.

Carbon-11 thymidine (TdR) uptake using positron emission tomography (PET) has been measured in ten patients with non-Hodgkin's lymphoma (NHL). The rate of TdR uptake (mean +/- s.d.) was of 0.009 +/- 0.006 mumol.100 cc-1.min-1 in low-grade NHL. This rate was 0.063 +/- 0.049 mumol.100 cc-1.min-1 in intermediate-grade NHL and 0.159 mumol.100 cc-1.min-1 in a patient with high-grade NHL. Lymphoma radioactivity reached a plateau at 0.42 +/- 0.22%. 100 cc-1 of the injected dose from 10 min after injection. The highest 11C uptakes were observed in the kidneys and in the liver (3.30 +/- 1.30 and 2.10 +/- 0.05%. 100 cc-1 of the injected dose, respectively). The lymphoma-to-muscle ratio was of 11.8 +/- 1.7, whereas the lymphoma-to-intestine ratio was of 1.5 +/- 0.7. Accordingly, the measurement of [11C]TdR uptake in the abdomen may need other imaging methods for adequate interpretation. The results suggest that [11C]TdR uptake using PET might be a method for noninvasively measuring cell proliferation in vivo.

Carbon Radioisotopes↗
PubMed1987

Assessment of bone marrow blood flow using positron emission tomography: no relationship with bone marrow cellularity.

Bone marrow blood flow has been assessed using positron emission tomography and the 15O-labelled carbon dioxide steady-state technique. The measurements were performed at the site of the posterior iliac crest. The bone marrow blood flow was 10.0 ml/min/100 cm3 +/- 3.0 (SD) in normal volunteers. It was markedly increased in patients with polycythaemia vera (26.9 +/- 4.6), chronic granulocytic leukaemia (25.2 +/- 3.9) and myelofibrosis (35.1 +/- 7.3). However, bone marrow blood flow did not differ from normal in patients with aplastic anaemia, chronic haemolysis or chronic lymphocytic leukaemia. There was no relationship between bone marrow cellularity and bone marrow blood flow. The data show that bone marrow blood flow is markedly elevated in polycythaemia vera, myelofibrosis and chronic granulocytic leukaemia and suggest that bone marrow cellularity is not a major factor in regulating bone marrow blood flow.

Bone Marrow↗
PubMed1986

Magnesium uptake by pancreatic islet cells is modulated by stimulators and inhibitors of the B-cell function.

28Mg2+ uptake by rat islets was measured during incubation with various stimulators or inhibitors of insulin release. D-Glucose induced a dose-dependent increase in 28Mg2+ uptake after 10 min or 120 min. The threshold concentration was around 6 mM and the maximum effect was observed with 15-20 mM glucose. After 120 min 28Mg2+ uptake was also stimulated by the metabolized sugars mannose, N-acetylglucosamine or glyceraldehyde, was unaffected by the non-metabolized or poorly metabolized L-glucose, galactose, 3-O-methylglucose, 2-deoxyglucose, fructose or mannoheptulose and was inhibited by glucosamine. The effect of glucose was markedly impaired by mannoheptulose, glucosamine, aminooxyacetate and NH4Cl, but was only partially decreased by D600 or diazoxide, which were ineffective in a glucose-free medium. Tolbutamide or KCl slightly increased 28Mg2+ uptake. Alanine, leucine alone or with glutamine, and ketoisocaproate also stimulated 28Mg2+ uptake, whereas arginine and lysine decreased it. These changes in 28Mg2+ uptake, brought about by various modifiers of the B-cell function, are thus similar but not identical to the changes in Ca2+ uptake, and are not the consequence of insulin release. The stimulatory effect of glucose requires glucose metabolism by islet cells, but is only partially due to depolarization of the B-cell membrane.

Amino Acids↗
PubMed1986

Quantitative assessment of erythropoiesis in bone marrow expansion areas using 52Fe.

Quantitative 52Fe scans were performed in 180 patients. Expansion of bone marrow was observed in 70. This bone marrow expansion was a nearly constant feature in haemolytic anaemia and in sideroblastic anaemia. It occurred in a third of the patients with myelofibrosis. In patients with polycythaemia rubra vera, expansion was noticed in only two out of seven. Erythropoiesis in expansion areas occurred despite persistence of fat in the iliac crest bone marrow biopsy. It could exist with a slight increase in erythropoiesis and might develop only after a long period of erythropoietic stimulation. Increased marrow activity can take place without erythropoietic expansion in long bones. The fraction of iron uptake in expansion areas did not exceed a third of total marrow iron uptake. With increasing erythropoiesis, the increase in iron uptake in expansion areas was less marked than the increase in the central areas. Erythropoiesis in expansion areas was usually not of major quantitative importance but could nevertheless reach the erythropoiesis of a normal adult.

Adult↗
PubMed1983

Glucose modulates Mg2+ fluxes in pancreatic islet cells.

Magnesium, the most abundant intracellular divalent cation, is an essential cofactor for many enzyme systems, but it remains unknown as to whether variations in the cytoplasmic concentration of ionized Mg2+ directly control cellular processes. Experiments with adrenal medullary cells made 'leaky' by exposure to high electric fields provided evidence that Mg2+ could influence hormone release not only by competing with Ca2+ for entry into the cell, but also at intracellular sites controlling exocytosis. A similar conclusion was reached for insulin release in a study using isolated rat islets also subjected to high voltage discharges. There is no experimental evidence, however, that physiological stimuli influence Mg2+ movements in intact secretory cells. We report here that 28Mg2+ fluxes in pancreatic islet cells are markedly modified by glucose, the physiological stimulus of insulin release, but not by its non-insulinotropic analogue, 3-O-methylglucose.

3-O-Methylglucose↗
PubMed1982

Assessment of bone marrow and splenic erythropoiesis in myelofibrosis.

The iron uptake in bone marrow and spleen was measured in 29 patients with myelofibrosis using 52Fe and quantitative scanning. In 10 patients, no iron uptake in the marrow could be observed and active erythropoiesis was extramedullary only. In the bone marrow of patients with myelofibrosis, the iron uptake per nucleated red cell was less than that observed in conditions without myelofibrosis or extramedullary erythropoiesis. Increasing splenic iron uptake was likely to be associated with a decreasing bone marrow iron uptake and was related to the size of the spleen. The data suggest that in myelofibrosis, the spleen dominates iron uptake through intense erythropoiesis and a high splenic blood flow, thus restraining iron supply to the bone marrow.

Adult↗
PubMed1982

Development of a reliable Hg-195m--Au-195m generator for the production of Au-195m, a short-lived nuclide for vascular imaging.

A new mercury-195m (T1/2: 41 hr) leads to gold-195m (T1/2: 30.6 sec) generator suitable for first-pass as well as steady-state radionuclide angiography studies has been developed. The distribution coefficients, Kd, for mercury (Hg-195m) and gold (Au-196), experimentally evaluated on chelating resin Chelex 100, showed this resin to be suitable as the column packing. Mercury-195m in a Trisma buffer solution at pH 7.40 was loaded on a chelating resin Chelex 100 column, together with gold carrier. Au-195m was eluted with an aqueous solution of 5% glucose in a 0.01M Trisma buffer at pH 7.70 (25 degrees C). Chemical assessment of the eluate has ensured that the eluted carrier-free gold is by no means colloidal: 80% is found in an ionic form, 20% as an uncharged species. Safe clinical use for routine diagnosis in humans is possible.

Gold Radioisotopes↗
PubMed1980

Measurement of erythropoiesis using 52Fe.

A method for determining erythropoiesis quantitatively with 52Fe has been applied to 25 patients with anaemia. The data were derived from quantitative scanning of the erythropoietic areas and the measurement of the plasma iron turnover. We have assessed this 52Fe measurement of erythropoiesis by comparing it with total marrow iron turnover studies. Both methods give similar estimates of erythropoiesis except in patients with severe ineffective erythropoiesis and in a patient with significant peripheral haemolysis, when erythropoiesis as measured with the 52Fe technique gave higher results. In these conditions, the estimate of total erythropoiesis might be more reliable using the 52Fe quantitative scanning technique. However, the measurement of erythropoiesis with 52Fe does not distinguish effective from ineffective erythropoiesis and cannot be applied to patients with extramedullary erythropoiesis.

Bone Marrow↗
PubMedDate not supplied

[Cerebral glucose metabolism in autistic children. Study and positron emission tomography].

Brain glucose metabolism was measured in 18 autistic children, using high resolution positron emission tomography (PET Scan), with fluorodeoxyglucose (FDG) as tracer. Measurements were performed on an ECAT III tomograph (CTI). Global brain glucose utilization in the autistic population was slightly more elevated than in young adult volunteers, particularly in frontal cortical regions, an observation previously reported for adult autists (Rumsey et al., 1985). However, mean brain glucose metabolism did not differ significantly from that of control children. Regional metabolic maps were also normal, although there was evidence for heterogeneities, particularly at the level of prefrontal and parieto-occipital association areas: 6 children showed a relative hyperfrontality whilst hypofrontality was found in 2 cases. These data suggest that PET might be useful for a better definition of subsets of autistic syndrome in children.

Adolescent↗