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Biomedical subjects

F Lavenne

Publications and source records attributed to F Lavenne.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effects of GABAA receptors activation on brain glucose metabolism in normal subjects and temporal lobe epilepsy (TLE) patients. A positron emission tomography (PET) study. Part I: Brain glucose metabolism is increased after GABAA receptors activation.

Though gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the human central nervous system, the metabolic response to GABA system activation remains imperfectly known. We studied in vivo with positron emission tomography (PET) the variations of glucose metabolism in the human brain after stimulation of the GABAA receptors by systemic administration of the specific GABAA agonist, 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP). These investigations were performed in three normal volunteers and as part of presurgical evaluation for temporal lobe epilepsy in six patients. While clinical and electroencephalographic (EEG) monitoring showed a sedative effect and sleepiness after THIP administration, glucose metabolism was paradoxically increased in grey matter structures, which are known to have a high density of GABAA receptors. These findings suggest that the pharmacological activation of GABA pathways, although inhibitory and producing a decrease of vigilance, increases the energetic demand at least during a phase of GABA agonist action, probably at the synaptic or at the glial cell level.

Adult↗
PubMed1994

Effects of GABAA receptors activation on brain glucose metabolism in normal subjects and temporal lobe epilepsy (TLE) patients. A positron emission tomography (PET) study. Part II: The focal hypometabolism is reactive to GABAA agonist administration in TLE.

Positron emission tomography (PET) using [18F]fluorodeoxyglucose (FDG) was used to study the metabolic response of focal hypometabolism to the administration of a specific GABAA agonist (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), THIP, in six temporal lobe epilepsy (TLE) patients. After THIP injection, the increase of glucose metabolism in the hypometabolic focus was larger than the mean increase reported in the whole brain (Part I; Epilepsy Res., 19 (1994) 45-54). Within the hypometabolic focus, this increase was significantly higher in regions with the lowest basal metabolic level. This metabolic response in the hypometabolic focus, observed in the absence of any epileptic discharge during FDG accumulation and PET data acquisition, suggests that GABAA receptors are up-regulated or, at least, preserved in TLE.

Adult↗
PubMed1993

Relief of akinesia by apomorphine and cerebral metabolic changes in Parkinson's disease.

The cerebral metabolic rate of glucose was measured in 14 Parkinson's disease patients with severe on-off fluctuations. Two positron emission tomography (PET) scans with [18F]fluorodeoxyglucose were performed, one after a challenge of subcutaneous apomorphine at a dose able to relieve akinesia within 15 min and the other with the vehicle. Apomorphine reduced glucose utilization by 4-6% in the lenticular nuclei and the occipital cortex and by 6-9% in the thalamic nuclei, but this effect was not statistically significant. Thus, central stimulation of dopamine receptors by apomorphine in advanced Parkinson's disease is not associated with cerebral metabolic changes as assessed by PET. Despite a dramatic improvement of the motor state, the global neuronal activity in the striatum and its downstream projections remains stable, suggesting an equilibrium between excitatory and inhibitory dopaminergic activities.

Aged↗
PubMed1991

Metabolic patterns associated with non-specific magnetic resonance imaging abnormalities in temporal lobe epilepsy.

We investigated the cerebral metabolic patterns associated with non-specific hyperintense T2-weighted image on Magnetic Resonance Imaging (MRI) in Temporal Lobe Epilepsy (TLE). Nineteen patients suffering from TLE with a normal CT scan underwent Positron Emission Tomography (PET) using 18F-fluorodeoxyglucose; 8 had hyperintense T2-weighted image on MRI in the epileptogenic temporal lobe and 11 had a normal MRI. Interictally, PET exhibited focal hypometabolism in all the patients with hyperintense T2-weighted image and in 8 of the 11 whose MRI was normal. The hypometabolic area was significantly more extensive in patients with hyperintense T2-weighted image in whom it always encompasses the site of the MRI abnormality. Moreover, these patients had higher metabolic asymmetry index in the temporal and parietal lobes than patients with a normal MRI. One patient with mesial temporal hyperintense T2-weighted image underwent an ictal PET, which showed that the focal hypermetabolism fitted remarkably with the site and size of the abnormal MR signal. Thus, non-specific hyperintense T2-weighted images are associated with particular interictal and ictal metabolic patterns which might suggest that these MRI abnormalities reflect an epileptogenic lesion.

Adolescent↗
PubMed1988

Cardiovascular risk factors in a sample of a rural Belgian population: the Bellux MONICA Study.

A sample of 1949 subjects of the population of the Belgian province of Luxembourg was screened for levels of cardiovascular risk factors. Cigarette smoking was more prevalent among males (51%) than among females (17%). The relationship between smoking and socio-economic status was inverse in males (M) and direct in females (F). Blood pressure (BP) measurements showed definite high BP in 10% of this sample, and 60% of those with definite high BP were not taking any hypertensive drugs. The average total cholesterol value was 6.49 mmol/L in M and 6.45 mmol/L in F. F had lower values than M at a younger age, but higher values than M at an older age. The high-density lipoprotein cholesterol was higher in F (1.57 mmol/L) than in M (1.27 mmol/L). Diabetes was present in 4.2% of this sample. In nearly half of these participants, the disease had been discovered during the screening. Obesity was especially frequently among F in all three age groups. In conclusion, the main cardiovascular risk factors were found to be at a fairly high level in this population sample.

Adult↗
PubMed1986

Alteration of left ventricular diastolic filling in hypertensive patients: effects of nitrendipine and atenolol.

This study was undertaken to determine the chronic effects of a long-acting calcium-channel blocker (nitrendipine) on resting left ventricular filling abnormalities in ten patients with essential hypertension. Radionuclide left ventricular curves of these hypertensive patients were compared with the curves of twelve normal volunteers and of eight asymptomatic older patients. The curves were analyzed for ejection fraction, peak filling rate (normalized for end-diastolic counts and for stroke counts), time to peak filling rate and filling fraction in the first-third of diastole normalized for cycle length. Heart rate and ejection fraction were similar in both control groups and hypertensive patients before and after nitrendipine. Before nitrendipine, diastolic filling parameters were significantly different in the hypertensive patients as compared with the volunteers and with the asymptomatic aged patients: peak filling rate was lower, time to peak filling rate was longer and the first-third filling fraction was smaller. After six weeks of nitrendipine therapy, systolic and diastolic blood pressure decreased significantly. After nitrendipine, the time to peak filling rate decreased and the first-third filling fraction and the peak filling rate (normalized for stroke counts) increased significantly. The acute oral administration of 100 mg atenolol induced a further decrease in systolic blood pressure and a significant decrease in heart rate. The effect of combining nitrendipine and atenolol on diastolic indexes was a preserved effect on time to peak filling rate and on the first-third filling fraction. These results suggest that short-term therapy with nitrendipine improves early diastolic dysfunction in hypertensives: the addition of a beta-blocking agent further improved the early diastolic indexes.

Adult↗
PubMed1985

[Role of adrenergic beta receptor partial agonists in left ventricular failure of ischemic origin. Value of xamoterol (ICI 118,587, Corwin)].

The ideal sympathomimetic derivative should possess the positive inotropic and relaxing effects of catecholamines whilst remaining free of their side-effects. Theoretically, such properties could be present in beta 1-adrenoceptor partial agonists. Xamoterol (ICI 118,587, Corwin; ISA 43 p. 100) seems to be the most promising beta 1 partial agonist. The aim of the study was to determine if the beneficial effects of Xamoterol were maintained during long term administration. Xamoterol (200 mg twice dialy) was administered to 14 patients with anterior myocardial infarction and moderate heart failure (class II-III NYHA). After 3 months' therapy, left ventricular function improved as indicated by reduction in left ventricular (LV) end-diastolic pressure (23 +/- 5 to 16 +/- 5 mm Hg; P less than 0.0005), LV end-diastolic volume (153 to 140 ml/m2; P less than 0.05) and in LV end-systolic volume especially in 11 patients with a control end-systolic volume less than 100 ml/m2 (- 15 p. 100; P less than 0.05). LV inotropic state was also enhanced as indicated by 21 p. 100 increases in EMax, the maximal LV pressure/volume ratio (P less than 0.02) and 20 p. 100 increases in the ratio end-systolic stress/ end-systolic volume (P less than 0.02). Myocardial oxygen consumption was unchanged, global lactate extraction fraction increased from 20 +/- 18 to 33 +/- 14 p. 100 (P less than 0.05) and LV alanine release was reduced (-1.7 to -0.2 muMol/min; P less than 0.05). The rate of LV pressure fall accelerated from 57 to 52 ms (P less than 0.05) and the mean diastolic wall stress was reduced by 35 p. 100 (P less than 0.05), reflecting the improvement in LV relaxation and diastolic function. Thus, the beneficial effects of Xamoterol were maintained after prolonged therapy particularly in patients with class II-III heart failure; patients in class IV benefited less from this therapy. No tachyphylaxis or side-effects were observed.

Administration, Oral↗
PubMed1984

Acute and long-term effects of nitrendipine on resting and exercise hemodynamics in essential hypertension.

The hemodynamic effects of nitrendipine have been studied at rest and during exercise in eight patients with mild to moderate essential hypertension. Acutely, nitrendipine (20 mg) induced at rest a decrease in arterial blood pressure (from 194/100 to 151/78 mm Hg) and an increase in heart rate (from 81 to 101 beats/min); the cardiac output was unchanged and the systemic vascular resistances fell by 30%. Similar changes were observed during exercise, i.e., a decrease in arterial blood pressure (from 245/106 to 204/87 mm Hg) and in systemic vascular resistances (-25%) with an increase in heart rate (from 133 to 142 beats/min). After chronic treatment during 55 days (average daily dose was 46 mg), the hypotensive effects of nitrendipine were similar, although less marked, both at rest and during exercise; the tachycardia noted after acute intake disappeared after chronic therapy. The addition of atenolol (100 mg) at the end of the chronic study in six patients further reduced arterial blood pressure at rest (138/80 mm Hg) and during exercise (180/91 mm Hg); the heart rate decreased to 60 beats/min at rest and 94 beats/min during exercise. These data show that nitrendipine is a potent antihypertensive agent that induces an important fall in the systemic vascular resistances both at rest and during exercise; during chronic therapy, these antihypertensive effects were maintained while the reflex tachycardia disappeared. The addition of atenolol during chronic therapy contributed to the normalization of the resting and exercise arterial blood pressures in nearly all patients.

Adult↗
PubMed1976

Superiority of developed over total pressure for heart contractility indices in dogs.

The independence of indices of contractility to Starling effects was tested in 6 closed-chest dogs. After vagal and beta-receptors blockade, indices calculated with total left ventricular isometric pressure (TP), were shown to be strongly dependent of rises in end-diastolic pressure (LVEDP) induced by dextran infusion. At LVEDP of 14.6 +/- 1.5, 22.2 +/- 1.1 and 32.8 +/- 1.5 mm Hg (+/- SEM), the peak value of velocity of the contractile elements calculated with total pressure (peak VCE, TP) diminished by 21, 40 and 50%, and the extrapolated value of VCE, TP at zero total pressure (Vmax, TP) diminished by 15, 30 and 44%. In contrast, indices calculated with developed pressure (DP = TP-LVEDP) at the same LVEDP were much less influenced, particularly the extrapolated value of VCE, DP at zero DP (V max, DP5) and (peak dP/dt)/DP did not significantly change. During angiotensin infusion, expected decreases in TP indices secondary to LVEDP rises were partially masked by simultaneous increases in contractility, and DP indices tended to rise. On the other hand, with minimal changes in LVEDP, as during calcium injection and paired stimulation, increases in TP and DP indices demonstrate inotropic effects equally well. Our study also shows that, besides Vmax calculated with DP, the instantaneous ratio of peak dP/dt and DP can also be proposed as a simpler and thus more convenient index of contractility independent of volume changes.

Angiotensin II↗
PubMed1975

[Prognosis and treatment of bacterial endocarditis. Review of 70 cases].

The long term results of medical and surgical treatments have been reviewed in 70 cases examined during the last 8 years. In 24 of them, bacterial endocarditis developed after valvular replacement. Antibiotic treatment was administered during at least 6 weeks. Determinations of the minimum inhibitory concentration of the antibiotic and of the bactericidal power of the serum were considered as the most important laboratory controls. In the post-operative cases with prosthetic valves, numerous pathogenic organisms were found, including gram (minus) bacilli and monilia, which may partly account for the high mortality in this group. Despite surgical reinterventions, 20 of the 24 patients died. For the gram (+) cocci, prognosis is however statistically worse (at the 99% confidence limit) when prosthetic valves are present. Out of the 46 patients without prosthetic valves, 31 (68%) had a favourable bacteriological and haemodynamic evolution; in this group, gram (minus) bacilli and monilia were never found to be the pathogenic organisms. For streptococci infections, recovery was obtained in 73% of the cases (24 out of 33). Percentages of long term recovery are very similar in mitral (67%) and aortic (69%) valvular involvment, but the frequency of surgical indication was very different in either group. In cases of aortic valvular disease, valvular replacement was indicated for bacteriological or haemodynamic reasons in 19 of the 20 patients who recovered. Amongst the 9 patients who died, 6 were not operated upon. Valvular replacement is by far less frequently necessary in cases of bacterial endocarditis on the mitral valve : one prosthetic valve amongst 8 patients who recovered. Finally, the authors discuss the place of surgery in the treatment of bacterial endocarditis. According to their experience, recent improvement in the prognosis of the disease seems to depend more on the surgical approach of the problem than on the discovery of new antibiotics.

Anti-Bacterial Agents↗