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Biomedical subjects

M Guillaume

Publications and source records attributed to M Guillaume.

At least 73 records · Page 4Linked to original sources
PubMed1988

Risk-benefit ratio of sodium fluoride treatment in primary vertebral osteoporosis.

The risk-benefit ratio of combined fluoride-calcium therapy in primary vertebral osteoporosis was examined prospectively in patients with at least one vertebral fracture. 257 patients were randomised to receive sodium fluoride 25 mg twice daily plus elemental calcium 1 g daily and a vitamin D2 supplement, and 209 received one of the alternative therapies usually prescribed in France. After a follow-up of 24 months the fluoride-calcium group showed a significantly lower rate of new vertebral fractures, the main adverse effect of the regimen being a higher incidence of osteoarticular pains in the ankle and foot; the risk of non-vertebral fractures was not increased, and digestive disorders arose with equal frequency in the two groups. Sodium fluoride 50 mg daily seems to represent a reasonable compromise in terms of anti-fracture effectiveness and side-effects.

Administration, Oral↗
PubMed1988

Automated production of potassium-38 for the study of myocardial perfusion using positron emission tomography.

The 35Cl(alpha, n)38K nuclear reaction was developed for the routine cyclotron production of repeated multimillicurie batches of 38K for dynamic studies of regional tissue perfusion with positron emission tomography. The objective is to make this isotope available as an alternative to the use of [13N]NH3 and 82Rb for the investigation of flow in experimental and clinical use. A sodium chloride powder target mounted on a water-cooled nickel backing is bombarded with 26 MeV helium-4 ions at a maximum beam current of 25 microA. The target is remotely disconnected from the bombardment port, transported to a hot cell and entirely processed by a computer-controlled system within a total time of less than 4 min. The final pyrogen-free isotonic and sterile solution of 38K has a radionuclidic purity of more than 99.99%. A typical yield of 19 +/- 2 mCi of 38K is obtained at the end of a 30 min bombardment at 10 microA. The production rate at saturation can therefore be estimated to 2.05 +/- 0.2 mCi/microA.

Coronary Circulation↗
PubMed1987

A new route for the synthesis of [18F]fluoroaromatic substituted amino acids: no carrier added L-p-[18F]fluorophenylalanine.

L-p-[18F]fluorophenylalanine was designed as a potential marker for probing protein synthesis in the human brain by positron emission tomography. This radiotracer has been synthesized using nucleophilic displacement of the activated nitro group of p-nitrobenzaldehyde by NCA 18F- obtained from the 18O (p, n) reaction on enriched water. The L-form of the [18F]fluoroamino acid can be separated on an analytical scale chiral column. A typical production run of 22.2 GBq (600 mCi) of 18F obtained after a 10 microA.h bombardment of 18 MeV protons on 99.8% 18O-enriched water leads to a batch of 1.11 GBq (30 mCi) of NCA L-p-[18F]fluorophenylalanine after a total synthesis time of 120 min.

Chromatography, High Pressure Liquid↗
PubMed1987

Preparation and evaluation of a hydrous tin(IV) oxide 82Sr/82Rb medical generator system for continuous elution.

Hydrous tin(IV) dioxide in the Na+-form appears to be the most efficient inorganic exchanger for a reliable and versatile clinical 82Rb generator. Continuous elution with a commercial physiological NaCl solution yields 82Rb ranging between 10 and 40% at a flow rate as low as 3 to 10 mL/min respectively. At the same time the Sr breakthrough is less than 1.6 10(-6)%/mL. A clinical generator loaded with 100 mCi 82Sr (150 mCi 85Sr) and continuously eluted for 3 min at a typical flow rate of 5 mL/min yields 40 mCi of 82Rb, 8 nCi of 82Sr and 11 nCi of 85Sr. The total absorbed radiation dose for 40 mCi 82Rb administered is primarily due to 82Rb and has been estimated for the three principal target organs as 760 mrad for the kidneys, 520 mrad for the heartwalls and 276 mrad for the lungs. The 82,85Sr contribution to the dosimetry has been shown to be negligible. The absence of radiolysis with generators loaded with high level of 82Sr was demonstrated by the excellent reproductibility of continuous elution properties of the generator during its practical shelf-life estimated to 5-6 weeks of clinical use which would require more than 30 L of eluent.

Humans↗
PubMed1987

Fast chemical synthesis of [75Se]L-selenomethionine.

A fast chemical synthesis of high specific activity [75Se]L-selenomethionine (10 Ci/mmol--370 GBq/mmol) is described with a view to 73Se labeling and PET studies. The overall radiochemical yield of the preparation is better than 80%. The purification method uses commercially available reverse phase HPLC columns and 9% NaCl as mobile phase. The final labeled compound is obtained in less than 3 h and the chemical, radiochemical and optical purities of the L-isomer are higher than 99.0%.

Humans↗
PubMed1987

[Scintigraphic study (81mKr) of venous return activation using intravenous dihydroergotamine].

We study by 81mKr radionuclide phlebography 13 normal lower limbs and 22 limbs suffering from sequelae of deep vein thrombosis. We assess the spontaneous venous return and the effect of an intravenous injection of 0.5 mg dihydroergotamine (DHE), a powerful venoconstrictor agent. The phlebograms are analysed on a morphological basis. Dynamic data are also collected: the delay of arrival of the radioactivity at the groin and the regional radioactivity level at steady state (during the steady 81mKr perfusion). This segmental radioactivity is a positive marker of the venous stasis because it increases when the venous system dilates and when the flow goes down. It is normalized with regard to the radioactivity measured in the proximal segment (lower vena cava and proximal iliac vein). The influence of DHE on the delay of arrival of the radioactivity in the groin is variable: it is regularly and significantly shortened in the normal limbs (mean decrease of 6.5 s, table II). The segmental radioactivity is relatively low among these limbs (2.76 at the pelvic level, 9.68 at the high, tables IV and V). It drops significantly with DHE in all segments (tables IV and V: -44% in the pelvic veins, -57% in the great saphenous vein and -46% in the femoral tract). The post-thrombotic limbs showing spontaneously an abnormal deep network are characterized by a high radioactivity level (total in the high: 14.25, deep system 5.70 and 8.55 in the saphenous vein, table V). This segmental total radioactivity does not decrease significantly under the influence of DHE; even more it increases in the deep tract (+24%, table V).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Dynamic isotopic phlebography using soluble krypton-81m.

Intravenous peripheral injection of krypton-81m in an isotonic solution permits venous scintigraphy of the lower limbs to be carried out. An anatomic definition of the obstructions and the collateral pathways is therefore easily displayed from the popliteal vein to the vena cava. The physical characteristics of the radionuclide permit iterative or sustained perfusions without accumulation of an excessive background noise and the method is used to obtain scintigraphic images in changing physiological conditions. Analysis of the dynamic data permits venous stasis to be assessed in terms of regional radioactivity at a steady state and transit rate. Various physiological and pathological conditions are analyzed by this method.

Hemodynamics↗
PubMed1986

Myocardial blood flow and glucose uptake after myocardial infarction.

Position emission tomography can picture the distribution of flow tracers as well as of metabolic substrates or analogs. Studies of the distribution of these tracers allow to infer information about regional myocardial clearance (flow X extraction) and substrate utilization. In a study of 32 patients after myocardial infarction, we have contrasted flow and substrate utilization to demonstrate ischemic but viable myocardium in the arterial territory of the infarct in a number of patients also specially after fibrinolytic reperfusion. Restoration of blood flow to the ischemic but viable myocardium through coronary bypass or dilatation improves flow from 56.3% to 84.2% of control and restores substrate utilization. In another group of 32 patients studied with the Strontium-82/Rubidium-82 generator, we have demonstrated perfusion changes both in the myocardial infarct area and at a distance. These changes predominate in patients with multiple vessel disease. Combined PET studies of flow and substrate utilization are new tools to study early intervention after myocardial infarction and to document the benefits of revascularization.

Aged↗
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↗
PubMed1986

A new osmium-191/iridium-191m radionuclide generator system using activated carbon.

A new osmium-191/iridium-191m (191Os/191mIr) radionuclide generator system has been developed based on the absorption of K2OsCl6 (Os-IV) on 140-230 mesh heat-treated activated carbon. The generator is eluted with pH 2 saline solution containing 0.25 g/l Kl to give 191mIr in good yield. The generator eluent is neutralized to physiologic pH and isotonicity with Tris buffer immediately prior to i.v. injection. No scavenger column is required. As an example, elution of the prototype generator with a 2-ml bolus results in elution of 191mIr in approximately 18% yield with an 191Os breakthrough of only 2 X 10(-4)%/bolus. The prototype generator has consistent performance over a 2-wk period with no change in 191mIr yield or 191Os breakthrough. Loading of up to 1.5 Ci of 191Os results in no observed radiolysis. Continuous elution of this system is also possible with a mean 191mIr yield of 3.7%/ml and a mean 191Os breakthrough of 2 X 10(-5)%/ml at a flow rate of 12 ml/min. This new system represents a readily available source of 191mIr for radioangiography. Adsorbed radiation dose calculations indicate a total-body dose of only 3.9 mrad for a 100 mCi injected bolus.

Adsorption↗
PubMed1986

Evaluation of the accuracy of steady-state krypton-81m method for calculating right ventricular ejection fraction.

The accuracy of a steady-state 81mKr method for calculating the right ventricular ejection fraction (RVEF) has been examined in this study. Causes of errors using this method and their effects on the calculated RVEF were evaluated. The results suggested that mixing in the right ventricle during continuous infusion of 81mKr was homogenous, allowing for the calculation of ejection fraction using the count rate ratio. Lung activity was quite important and could not be neglected in computing RVEF, but the use of [99mTc]MAA lung perfusion scanning seemed to allow a correct subtraction of this background activity. The delineation of right ventricular regions of interest (ROIs) was complicated by the translation movements of the right ventricle during heart contraction. These ROIs should be drawn carefully on the count density distribution images and data shown by parametric images; such as first and second harmonic phase, amplitude images, and composite stroke volume image should be considered. Furthermore, this study demonstrates the superiority of the 81mKr technique compared with 99mTc methods for computing RVEF. In conclusion, even if the true accuracy of the 81mKr method for calculating RVEF cannot be proven due to the lack of reference methods, strong, suggestive evidence that the technique should be accurate is shown here.

Adult↗
PubMed1985

Evaluation of methods for qualitative and quantitative assessment of esophageal transit of liquid.

The aim of this work was to compare the advantages and the limitations of several data processing techniques for the assessment of esophageal transit. The following qualitative methods were evaluated: scintigraphic image, cine-display, regional time-activity curve, and condensed image. The quantitative methods evaluated were the pixel to pixel presentation of parameters of the time-activity curves such as time of arrival, time to maximum, and several downslope parameters, mean transit time, mean time, and a new transit parameter based on the radioactive decay. The study allowed us to conclude that for the detection and the quantitation of esophageal transit the method of choice was the combined use of the condensed image and the pixel to pixel mean time image. The parametric image using the transit parameter calculated from decay was shown as a valuable alternative if an ultra-short half-life radionuclide was used as the tracer.

Esophagus↗
PubMed1985

Evaluation of esophageal transit in children and in infants by means of Krypton-81m.

This paper presents the results of Krypton-81m esophageal transit study in a series of children and infants presenting various esophageal disorders. The advantage of Kr-81m, compared to other radionuclides, is that the radiation dose to the patient is extremely low. The study can therefore be repeated as often as necessary and a high dose can be given to ensure good quality results. The method is very easy to perform and allows a quantitative assessment of esophageal transit in physiological conditions. The method gives information about the severity of altered transit and it is particularly useful in studying the effects of treatment.

Adolescent↗
PubMed1985

Measurements of cell-mediated cytotoxicity on target cells labelled with the indium-111-oxine complex.

The preparation is given of an 111indium-oxine complex that is non toxic and can label reproductively various types of cells. They retain the label for long periods (24 hours and more). This method gives parallel results for cell-mediated cytotoxicity measurements to Chromium-51 labelling and is found to have wider uses. It can label cells that release 51Cr too fast, makes possible long term measurements of cytotoxicity and accurate counts on small numbers of target cells.

Animals↗
PubMed1984

[Uni- or bipolar temporary exclusion of the esophagus by stapling. A simple technic, not damaging to the esophagus].

Many surgical procedures have been put forward to treat perforations of the thoracic oesophagus seen late. The authors propose a simple stapling technique which can be applied in the cervical segment or below the lesion if required, and report the results obtained in 4 cases. The spontaneously reversible temporary derivation obtained ensures better healing of the lesion and avoids the need for subsequent reconstructive surgery.

Aged↗
PubMed1984

Quantitation of esophageal transit by means of 81mKr.

A method for quantifying esophageal transit by means of 81mKr is described. The principal advantage of 81mKr compared with 99mTc is its ultra-short half-life with its consequences on radiation dose and counting statistics. Factors which may influence the esophageal transit time such as body posture, volume of the tracer, and the nature of the tracer were studied. The reproducibility of the technique is quite good and its capacity to detect minor esophageal transit disorders is demonstrated.

Adult↗