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J C Depresseux

Publications and source records attributed to J C Depresseux.

At least 19 recordsLinked to original sources
PubMed2000

Spatial distribution of blood flow in electrically stimulated human muscle: a positron emission tomography study.

Neuromuscular electrical stimulation (NMES) was studied with positron emission tomography (PET) and H(2)(15)O in the quadriceps muscle of 11 men. The subjects were submitted to simultaneous bilateral isometric contraction (5 s)-rest (5 s) cycles for 12 min, with a workload corresponding to 5% of quadriceps maximal isometric voluntary torque (QMIVT) for one thigh (5%T) and 10% of QMIVT for the other (10%T). Scans were centered at the electrodes and tissue blood flow (TBF) was evaluated in square regions of interest (ROIs) (3.5 cm(2)) in the transverse section (TS) of both thighs. The mean TBF reached 8.9 mL min(-1) 100 g(-1) in the TS of the 5%T and 11.5 mL min(-1) 100 g(-1) in the TS of the 10%T (P > 0.05). A negative linear relationship was found for both thighs between the ROI-electrode distance and the TBF (P </= 0.009). The mean percentage of activated ROIs (TBF > 5 mL min(-1) 100 g(-1)) was lower in the 5%T than in the 10%T (50.6% vs. 62.2%; P = 0.017). With NMES, the pattern of spatial recruitment appears linked to electrode proximity and is spatially extended. These results confirm the utility of combining NMES with voluntary exercise in the treatment of atrophied muscle.

Adult↗
PubMed1995

Radiation dosimetry for bolus administration of oxygen-15-water.

UNLABELLED: We describe the development of a biokinetic model which permits an estimation of organ activities and the dosimetry of a bolus of 15O-water. The aim of this study was to estimate time-activity functions and deduce the cumulated activities in different organs so that the radiation absorbed dose values can be estimated. METHODS: The model we used includes the right heart chambers, lungs, left heart chamber, brain, liver, kidneys, muscles, gastrointestinal tract and the remainder of the body. Activity in an organ will decay by physical decay with the decay constant, lambda, and can diffuse in the organ. An exception is the heart, where blood is ejected from the heart chambers. Depending on the location of the organ in relation to the blood sampling point, organ activities can be calculated by convolution or deconvolution. RESULTS: The radiation absorbed dose values were estimated and an effective dose equivalent HE of 1.16 microSv/MBq (4.32 mrem/mCi) as well as an effective dose E of 1.15 microSv/MBq (4.25 mrem/mCi) were calculated. The cumulated activities in select organs measured by PET gave good agreement with the values calculated by this model. CONCLUSION: The values of effective dose equivalent and effective dose for bolus administration of 15O-water calculated from the absorbed doses estimated by the proposed kinetic model are almost three times higher than those previously published. A total of 8700 MBq (235 mCi) of 15O-water can be administered if an effective dose of 10 mSv (1 rem) is accepted.

Half-Life↗
PubMed1991

Assessment of flow and oxygen delivery to the lower extremity in arterial insufficiency: a PET-scan study comparison with other methods.

The authors studied muscular blood flow (F), oxygen consumption rate (R), and oxygen extraction fraction (E) in 5 patients suffering from severe intermittent claudication (stage II). They applied the bolus technique of H2150 and 1502 with a detection by positron emission tomography (PET). Tomograms were recorded at the greatest diameter of the calves, at rest and ten minutes after a treadmill walk test leading to the development of ischemic pain in the affected extremity. F and E data were compared with the values obtained by more usual methods, namely occlusive venous strain gauge plethysmography and femoral venous blood sampling. During the study, these patients received naftidrofuryl, a vasodilatator drug, in an intravenous dose of 600 mg diluted in 250 mL saline infused over a six-hour period in a placebo-controlled, double-blind, crossover protocol (two consecutive experiments, a week apart). The results showed that all blood flow values measured at rest and after exercise by PET were in close correlation (r = 0.71) with the plethysmographic findings. The agreement between the two methods of measuring blood flow was less obvious with an Altman's presentation of the data: there was a tendency to measure higher values with PET scan. Concerning E, the correlation was poor at rest. After exercise, the values were more elevated with PET and no correlation was found with blood samples. The authors found no significant effect of naftidrofuryl either on flow or metabolic data.

Double-Blind Method↗
PubMed1990

Metabolic and circulatory evaluation of cerebral ischemic accident in humans by positron emission tomography: a pilot study with almitrine-raubasine.

Positron emission tomography and oxygen-15 were used to evaluate the effect of almitrine-raubasine combination on cerebral blood flow and oxidative metabolism in patients with cerebral ischemia. In five patients aged between 58 and 74 years, with a cerebral ischemic accident in the territory of the middle cerebral artery, blood flow rate, oxygen metabolic rate, and cerebral oxygen extraction were measured before and after a 90-min intravenous perfusion of almitrine bismesilate 15 mg and raubasine 5 mg. Investigations were performed from day 2 to day 7 after stroke occurred. One patient showed evidence of initial relative luxury perfusion, the degree of which was reduced by such combined treatment. The other four patients had a focal reduction in cerebral blood flow and oxygen consumption prior to treatment. The statistical analysis of three cerebral areas (epicenter of lesion, anterior and posterior juxtalesional areas, and homologous heterolateral areas) showed a 3.6% increase in oxygen metabolic rate at the epicenter, when both hemispheres were taken together, and a significant increase in cerebral blood flow in all three areas (3% on the healthy hemisphere, 13% on the injured hemisphere). These changes were greater in some patients than in others. This suggests that heterogeneity of drug responses may correspond to the heterogeneity of the initial status.

Aged↗
PubMed1988

[Regional blood flow and oxygen consumption in the leg muscles of normal subjects and in those with arterial insufficiency. Study of the distribution of C15O2 and of 15O2 using positron emission tomography].

We first studied the distribution of radioactivity during continuous inhalation of C15O2 and 15O2 in traverse tomograms of the greatest diameter of legs, at rest and immediately after exercise (ankle flexions). C15O2 and 15O2 were distributed homogeneously and symmetrically in both legs of normal subjects at rest. The activity accumulated in the anterolateral region after exercise. In patients, this pattern of distribution was similar but asymmetrical, depending on the arterial pathology. No systematic distribution of either C15O2 or 15O2 was observed. In a second step, we studied quantitatively blood flow (F), oxygen uptake (R) and oxygen extraction (E) in 11 subjects: 5 normals (23 +/- 1 years) and 6 patients (60 +/- 11 years) suffering from unilateral intermittent claudication. We used the bolus inhalation technique of C15O2 and 15O2. In the normal leg at rest, ranges were 2.5 to 8.0 ml/min.hg for F, 0.9 to 21.3 mumol/min.hg for R and 3.6 to 33.4% for E. In the pathological leg at rest, ranges were 3.7 to 11.3 ml/min.hg for F, 3.8 to 10.6 mumol/min.hg for R and 7.1 to 24.5% for E. After exercise, ranges were 6.4 to 62.8 ml/min.hg for F, 66.0 to 386.3 mumol/min.hg for R and 29.2 to 89.5% for E in both legs. There was no straight difference between normal and pathological legs soon after exercise. This study allows us to expect that the demonstration of such a difference implies a longer delay of data acquisition following the slow post-ischemia recovery.

Adult↗
PubMed1987

[Metabolic and blood circulation evaluation of acute ischemic cerebral accident in humans using positron emission tomography].

Positron emission tomography and oxygen-15 were used to evaluate the effects of an almitrine-raubasine combination on cerebral blood flow and oxydation metabolism in patients with acute cerebral ischaemia. In 5 patients, aged between 58 and 74 years, with cerebral ischaemic accident in the territory of the middle cerebral artery, blood flow rate, oxygen consumption and brain oxygen extraction were measured before and after a 90-min intravenous infusion of almitrine bismesilate 15 mg and raubasine 5 mg. Only one patient presented with initial relative luxury perfusion, the intensity of which was reduced by the combined treatment. The other 4 patients had focal reduction of cerebral blood flow and oxygen consumption prior to treatment. Statistical analysis conducted on three cerebral areas (epicentre of the lesion, anterior and posterior juxtalesional areas and homologous heterolateral areas) showed a significant 3.6% increase of oxygen consumption in the epicentre, both hemispheres included, and a significant increase of cerebral blood flow in all three areas (3% on the healthy side, 13% on the diseased side). No significant change in oxygen extraction was demonstrated. The authors conclude that acute almitrine-raubasine treatment has beneficial effects on the brain immediately after a cerebral vascular accident, reflecting respect of the circulation-metabolism couple.

Acute Disease↗
PubMed1987

[Recent concepts on cerebral ischemia in humans and their implications in therapeutic evaluations].

Recent concepts concerning focal cerebral ischaemia in man and resulting from the data obtained with positron emission tomography are reported. The evolutive steps in the ischaemic process are divided into: perfusion reserve; extraction reserve recruitment; ischaemic penumbra; lesional process, and post-lesional developments. Circulatory and metabolic patterns corresponding to these evolutive steps are described and illustrated. The potentials of these data as guide-lines in therapeutic trial methodology are discussed.

Brain↗
PubMed1986

Mathematical model of the metabolism of 123I-16-iodo-9-hexadecenoic acid in an isolated rat heart. Validation by comparison with experimental measurements.

The aim of the present study was to demonstrate that it is possible to estimate the intracellular metabolism of a fatty acid labelled with iodine using external radioactivity measurements. 123I-16-iodo-9-hexadecenoic acid (IHA) was injected close to the coronary arteries of isolated rat hearts perfused according to the Langendorff technique. The time course of the cardiac radioactivity was measured using an INa crystal coupled to an analyser. The obtained curves were analysed using a four-compartment mathematical model, with the compartments corresponding to the vascular-IHA (O), intramyocardial free-IHA (1), esterified-IHA (2) and iodide (3) pools. Curve analysis using this model demonstrated that, as compared to substrate-free perfusion, the presence of glucose (11 mM) increased IHA storage and decreased its oxidation. These changes were enhanced by the presence of insulin. A comparison of these results with measurements of the radioactivity levels within the various cellular fractions validated our proposed mathematical model. Thus, using only a mathematical analysis of a cardiac time-activity curve, it is possible to obtain quantitative information about IHA distribution in the different intracellular metabolic pathways. This technique is potentially useful for the study of metabolic effects of ischaemia or anoxia, as well as for the study of the influence of various substrates or drugs on IHA metabolism in isolated rat hearts.

Animals↗
PubMed1986

Regional cerebral blood flow and metabolic rates in human focal epilepsy and status epilepticus.

Positron emission tomography with the oxygen-15 steady state or bolus inhalation technique was used to provide quantitative values of regional cerebral blood flow (CBF), oxygen extraction ratio (OER) and oxygen consumption (CMRO2) in 25 patients with partial complex seizures during the interictal state and in 5 patients during status epilepticus. Glucose utilization (CMRglu) was also studied in one case of status epilepticus with the 18F-fluorodeoxyglucose technique (18FDG). Interictal scans showed zone(s) of hypoperfusion and hypometabolism without significant variation of the OER in approximately 80% of patients. In 62%, there was a strong correlation between the overall EEG localization and the area(s) of hypoperfusion and hypometabolism. In all cases, ictal scans revealed a focal or multifocal increase in CBF and CMRO2. The localization of the most affected regions correlated well with the spatial distribution of the electroencephalograph (EEG) abnormalities. Comparison of the different values of CBF, CMRO2, and OER showed that the increase in perfusion always exceeded that of oxygen consumption and hence was accompanied by a significant decrease of OER; the latter was always the most prominent in the region of the epilepticus focus determined by serial EEG recordings. These results showed that the supply of oxygen by blood flow is large enough to meet metabolic demand. When comparing these values with CMRglu, it appeared that the relative changes in CMRglu and CBF were very similar, indicating that the increase in blood flow correlated with the enhancement in glucose utilization. The observed imbalance between blood flow, glucose utilization, and oxygen consumption could suggest that an impairment of oxygen utilization by the mitochondria could occur in the epileptic focus during prolonged status epilepticus.

Cerebrovascular Circulation↗
PubMed1982

Renal control of the peripheral uptake of exogenous gastrin in the dog.

The extraction of plasma gastrin during intravenous infusion of exogenous hormone has been measured in the head, gastrointestinal tract, or kidney of dogs submitted to sham surgery, evisceration, or binephrectomy without or with subsequent kidney transplantation. A significant gastrin extraction was demonstrated not only in the kidney, but also in the head and in the gastrointestinal tract; moreover, plasma gastrin extraction in the head and the bowel was considerably reduced by binephrectomy and was brought back to control values after subsequent kidney transplantation. A non-specific effect of surgery and a variation in peripheral blood flow seem to be excluded. Thus a control by the kidney of the peripheral removal of blood gastrin is evidenced, the mechanism of which remains hypothetical.

Animals↗
PubMed1981

An introduction to the measurement of the cerebral oxygen uptake rate by inhalation of 15O2; analysis of the contribution of 15O2 and H2 15O in brain radioactivity.

This paper introduces a model for the computation of the regional cerebral metabolic rate of oxygen from the data of cerebral regional radioactivity collected after inhalation of 15O2. A method was devised for the differential determination of the respective contribution of radiooxygen and of radiowater in the inflow and the outflow of radioactivity in the brain after or during such on inhalation. The results demonstrate the feasability of such a model and outline some of the methodological to be taken into account in the numerical analysis of the data.

Animals↗