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Biomedical subjects

G Franck

Publications and source records attributed to G Franck.

At least 73 records · Page 4Linked to original sources
PubMed1991

Decrease of frontal metabolism demonstrated by positron emission tomography in a population of healthy elderly volunteers.

Frontal metabolism measured with positron emission tomography is shown to be decreased relatively to that in other cortical or sub-cortical areas, in a population of healthy elderly compared to young volunteers. Cortical atrophy or neuronal depopulation are unlikely to entirely explain this physiological phenomenon, and sub-cortico-cortical deactivation should play a role, analogous to that proposed in subcortical diseases.

Aged↗
PubMed1991

[Postures and abnormal paroxysmal movements during sleep: hypnogenic paroxysmal dystonia or partial epilepsy?].

In recent years, a differentiation has been made between two syndromes that are characterized by brief abnormal paroxysmal movements occurring principally at night: 1, hypnogenic paroxysmal dystonia (HPD), sometimes considered a particular form of dystonia similar to paroxysmal kinesigenic choreoathetosis, and 2, mesiofrontal epilepsy. Whether HPD is a distinct syndrome is not clear. Twenty-three patients, 11 men and 12 women, were hospitalized between 1985 and 1989 for examination of this type of abnormal paroxysmal movements (APM) occurring at night. In order to clarify the physiopathology of these abnormal nocturnal movement as focal epilepsy or a particular form of dystonia, we analyzed the personal and familial antecedents of all 23 patients, the polygraphic records during waking and sleep periods, and the results of neuroradiological examinations. Four patients were examined by positron emission tomography (PET) using i8F deoxyglucose. Symptoms first appeared between 3 and 28 years of age (M, 10.1) and developed over 1 to 20 years (M, 10.1). APM clearly occurred more commonly (greater than 90%) during sleep, usually during phases of slow-wave sleep. The sleeping patient opened his eyes and the motor signs then variously associated affective facial expression; axial postural modifications; tonic, dystonic or choreic postural movements of the limbs; pedalling; automatisms; disordered agitation and vocalization. The seizure was abruptly interrupted after 10 to 60 seconds. There was usually no postictal confusion. Thirteen patients clearly had clear epileptic antecedents: in 9, generalized tonic-clonic seizures; in 4, focal epileptic status. During nocturnal polygraphic recording, 6 patients presented a generalized seizure following a period of APM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Tissue and blood magnesium levels in spontaneously hypertensive rats, at rest and in stressful conditions.

Magnesium (Mg) levels were measured by flame atomic absorption spectrophotometry in the blood (plasma, erythrocytes) and soft tissues (liver, brain, heart, aorta, kidneys, adrenals, spleen, thymus) of adult spontaneously hypertensive rats (SHR) and their normotensive controls, Wistar Kyoto (WKY). In experiment 1, Mg determinations were performed on eight animals of each strain at rest. Mg levels were lower in brain (P less than or equal to 0.05), kidneys (P less than or equal to 2.10(-4] and erythrocytes P less than or equal to 0.01) in SHR than in WKY rats. Tissue water content was the same in the two strains. These results suggest the occurrence of lower intracellular Mg levels in SHR than in WKY. In experiment 2, 15 SHR and 15 WKY were submitted either to acute (1 d) or subacute (22 d) stresses or reared in restful conditions. Acute stress induced important Mg shifts leading to a decreased difference between SHR and WKY in most tissues and to an increased and more significant difference (P less than or equal to 0.01) in spleen and plasma Mg levels. Subacute stress was milder and had little effect. It is concluded that the results of experiment 1 cannot be attributed to the greater sensitivity of SHR to laboratory manipulations. When compared with previously published data our results nevertheless suggest an association between stress sensitivity and genetic factors regulating Mg metabolism.

Animals↗
PubMed1990

Cerebral glucose utilization during sleep-wake cycle in man determined by positron emission tomography and [18F]2-fluoro-2-deoxy-D-glucose method.

Using the [18F]fluorodeoxyglucose method and positron emission tomography, we studied cerebral glucose utilization during sleep and wakefulness in 11 young normal subjects. Each of them was studied at least thrice: during wakefulness, slow wave sleep (SWS) and rapid eye movement sleep (REMS), at 1 week intervals. Four stage 3-4 SWS and 4 REMS fulfilled the steady state conditions of the model. The control population consisted of 9 normal age-matched subjects studied twice during wakefulness at, at least, 1 week intervals. Under these conditions, the average difference between the first and the second cerebral glucose metabolic rates (CMRGlu was: -7.91 +/- 15.46%, which does not differ significantly from zero (P = 0.13). During SWS, a significant decrease in CMRGlu was observed as compared to wakefulness (mean difference: -43.80 +/- 14.10%, P less than 0.01). All brain regions were equally affected but thalamic nuclei had significantly lower glucose utilization than the average cortex. During REMS, the CMRGlu were as high as during wakefulness (mean difference: 4.30 +/- 7.40%, P = 0.35). The metabolic pattern during REMS appeared more heterogeneous than at wake. An activation of left temporal and occipital areas is suggested. It is hypothetized that energy requirements for maintaining membrane polarity are reduced during SWS because of a decreased rate of synaptic events. During REMS, cerebral glucose utilization is similar to that of wakefulness, presumably because of reactivated neurotransmission and increased need for ion gradients maintenance.

Adult↗
PubMed1990

Quantitative analysis of 18/FDG-PET in the presurgical evaluation of patients suffering from refractory partial epilepsy. Comparison with CT, MRI, and combined subdural and depth. EEG.

CT, MRI, 18/FDG-PET and Depth. EEG, performed with subdural and depth electrodes were part of the presurgical evaluation in 22 patients. Statistical analysis of 18/FDG-PET was performed to compare cerebral utilization of glucose to that of normal age matched controls. The findings of CT, MRI, and quantitative analysis of PET are compared with those of ictal Depth. EEG. A positive correlation between CT and Depth. EEG was obtained in 23% of the patients and between MRI and Depth. EEG. in 50%. For both imaging techniques a negative correlation was found in 5%. Regional abnormalities were found with quantified PET in 95% of the patients and were concordant with Depth. EEG. for side of onset in 77% of the patients and for lobe of onset in 59%. A possibly false localising PET result for lobe of onset was obtained in 8 patients (36%). Limitations of PET were most apparent in patients with regional mesiolimbic or bilateral seizure onset. A favourable outcome of surgery was associated usually with positive convergence of both methods. PET may be a valuable contribution to the research and management of partial complex epilepsy, but at present cannot be considered a reliable alternative to invasive EEG methods in patients without clear unilateral focus localization on surface EEG.

Adolescent↗
PubMed1990

Reproducibility of cerebral glucose utilization measured by PET and the [18F]-2-fluoro-2-deoxy-d-glucose method in resting, healthy human subjects.

The stability of cerebral glucose utilization was examined in nine right-handed, healthy men (age, 24.88 +/- 2.93 years) using positron emission tomography (PET) and the [18F]-fluorodeoxglucose (FDG) method. Each study was run twice at intervals of 1-12 weeks with the subject at rest. The average cerebral metabolic rate for glucose (CMRGlu) was 5.40 +/- 0.71 mg/100 g per min (coefficient of variance, 13.08). The average intraindividual variation of CMRGlu was 7.91% +/- 15.46% (P = 0.13). Metabolic indices (MI: regional/mean cortical CMRGlu) were used to determine the regional cerebral metabolic distribution. The interindividual (coefficient of variance, 7.13) and intraindividual variabilities (average variation, -0.12% +/- 8.76%) of MI were smaller than those of metabolic rates. No reproducible significant asymmetry was observed. The FDG method used with subjects at rest thus yields low intraindividual variability of both cerebral glucose consumption and regional metabolic distribution, even at an interval of several weeks. Cerebral glucose utilization measured under such conditions may act as a reliable reference for determination of the influences of physiological (activation), pharmacological or pathological processes on cerebral glucose metabolism.

Adult↗
PubMed1990

Blood and tissue zinc levels in spontaneously hypertensive rats.

Zinc (Zn) determinations were performed on blood plasma and red cells, liver, heart, adrenals, and spleen of spontaneously hypertensive (SHR) and control normotensive (WKY) male rats, 20 weeks of age. SHR revealed higher red cell (p = 2 x 10(-5)) and heart (p = 0.007) Zn levels than WKY rats. The water content of organs was the same in the two strains. When compared with published data, these results suggest an association between high cell Zn levels and hypertension, the meaning of which is briefly discussed.

Adrenal Glands↗
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↗
PubMed1990

Moclobemide versus clomipramine in the treatment of depression: a double-blind multicentre study in Belgium.

Moclobemide and clomipramine were compared for efficacy, tolerance and safety in 63 mixed endogenous and nonendogenous depressed patients. Treatment was given for at least 4 weeks in a double-blind, randomized, parallel-group design. The mean Hamilton Rating Scale for Depression score decreased gradually during treatment with no differences between groups. Two patients on clomipramine and none on moclobemide were withdrawn for lack of efficacy, and poor tolerance caused 3 patients on moclobemide and 7 on clomipramine to stop treatment prematurely. Patients with endogenous depression responded better to clomipramine, whereas nonendogenous disorders did better on moclobemide. Adverse events were more frequent in the clomipramine group and more of these were severe or very severe than for moclobemide. Thus, although no significant difference in efficacy was seen, moclobemide appeared to be tolerated better than clomipramine. The numbers were small, however, and many patients received concomitant medication, and the results are therefore difficult to interpret.

Antidepressive Agents↗
PubMed1990

Identification of the side of epileptic focus with 123I-Iomazenil SPECT. A comparison with 18FDG-PET and ictal EEG findings in patients with medically intractable complex partial seizures.

123I-Iomazenil SPECT was performed in 17 patients who were considered candidates for surgery of epilepsy because of medically intractable complex partial seizures. In addition to this examination their presurgical evaluation consisted of long term ictal EEG-CCTV monitoring, CT, MRI and 18FDG PET. In eight patients intracranial ictal EEG recordings were performed. SPECT was assessed visually while PET data were analyzed quantitatively. Both SPECT and PET were compared to ictal EEG data and showed asymmetries in over 80% of patients in agreement with EEG findings. These three methods were in agreement in 65% of patients. SPECT showed abnormality contralateral to the EEG focus in one patient (6%) while PET always demonstrated ipsilateral dysfunction. It is concluded that 123I-Iomazenil SPECT may be considered a more economical and more widely available alternative to 18FDG PET in the presurgical evaluation of patients with medically intractable complex partial seizures. In this respect 123I-Iomazenil specifically reflects functional changes in the membranes of neurons while 18FDG is related to glucose metabolism not only of neurons but also of glial cells.

Adult↗
PubMed1990

A plasma factor inhibiting erythrocyte magnesium efflux.

When incubated at 37 degrees C for 5 h in a magnesium- and calcium-free phosphate buffer solution (PBS), rat and mouse erythrocytes lose 30-40% of their Mg content. However, no Mg loss is observed if these erythrocytes are incubated in their own plasma. In order to investigate this phenomenon, murine erythrocytes were incubated in PBS, in human and murine blood plasmas, and fetal calf serum diluted in PBS (1/4), and in PBS supplemented with MgCl2, CaCl2, and crystallized plasma proteins at concentrations equal to those obtained in plasma/PBS solutions. Erythrocyte Mg efflux was significantly inhibited (P = 10(-8] by diluted human and rat plasmas but the time course of this inhibition was different with these two kinds of plasmas (P = 10(-4]. Mouse plasma and fetal calf serum also entailed a significant inhibition of Mg efflux, while the addition of Mg, Ca, and purified plasma proteins in the incubation medium had little effect. Blood plasma thus contains a factor inhibiting Mg efflux from murine erythrocytes and this effect is not explained by its content of magnesium, calcium, and proteins.

Animals↗
PubMed1989

Correlation between total and free magnesium levels in human red blood cells. Influence of HLA antigens.

Total and free magnesium contents were determined by atomic absorption spectrophotometry and 31P nuclear magnetic resonance on red blood cells of healthy blood donors of known HLA groups. A statistically significant correlation was found between free and total magnesium contents (r = 0.67, P less than 0.02). The previously described low total magnesium contents in HLA-B35+ subjects were associated with low free Mg2+ contents. Therefore, total and free magnesium and HLA-associated genetic factors are closely related.

Erythrocytes↗