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Biomedical subjects

F Brunotte

Publications and source records attributed to F Brunotte.

At least 73 records · Page 4Linked to original sources
PubMed1992

Right ventricular overload and induced sustained ventricular tachycardia in operatively "repaired" tetralogy of Fallot.

The aim of the study was to evaluate the main predictors of the inducibility of sustained ventricular tachycardia (VT) in patients with repaired tetralogy of Fallot. Thirty-five patients (age 12 +/- 6 years) underwent right-sided cardiac catheterization, echocardiography, radionuclide angiography and ventricular stimulation; 10 had (group 1) and 25 had no (group 2) sustained VT. Group 1 patients were significantly older at the time of surgery and had longer follow-up periods (7 +/- 3 vs 4 +/- 4 years, p less than 0.02; and 12 +/- 4 vs 5 +/- 2 years, p less than 0.001, respectively). Right ventricular (RV) systolic pressure, end-systolic and end-diastolic normalized RV volumes were higher in group 1 (48 +/- 14 vs 38 +/- 11 mm Hg, p less than 0.05; 1.23 +/- 0.2 vs 0.86 +/- 0.17, p less than 0.001; and 2.35 +/- 0.37 vs 1.70 +/- 0.22, p less than 0.001, respectively). RV end-diastolic pressure, left ventricular and RV ejection fractions were similar in the 2 groups. A stepwise discriminant analysis was made to predict patients with inducible sustained VT (group 1): Time period from surgery to follow-up (p less than 0.001), normalized RV end-systolic volume (p less than 0.002) and RV systolic pressure (p = 0.01) were higher in group 1 and allowed classification of 90% of patients in group 1 and 96% in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Determination of free creatine and phosphocreatine concentrations in the isolated perfused rat heart by 1H- and 31P-NMR.

To measure free creatine in the isolated perfused rat heart, the concentration of phosphocreatine, and phosphocreatine plus creatine (sigma Cr) were measured by 31P- and 1H-NMR, respectively. Quantification was performed in the presence and absence of an intraventricular balloon filled with a known amount of PCr, which acted as an external standard. Total (free plus bound) phosphocreatine and creatine were measured by HPLC analysis of extracts from the same hearts, freeze-clamped at the end of the perfusions. A greater concentration of creatine (mumol/g dry wt.) in the perfused rat heart was measured by HPLC analysis (40.3 +/- 2.38 (11)) as compared to NMR (34.6 +/- 1.95 (11)), whilst no significant difference was observed in the measurement of phosphocreatine between the two assay methods. Consequently, a greater sigma Cr was measured by HPLC. This work suggests that the majority of Cr in the heart is NMR visible and unbound, so available to interact with creatine kinase. The lower free ADP concentration calculated from NMR measurements (53.3 +/- 3.80 microM (9)) was not significantly different from that determined by HPLC analysis (56.9 +/- 5.90 microM (9)). This suggests that the concentration of free ADP in the heart is higher than values where it can regulate oxidative phosphorylation most effectively.

Animals↗
PubMed1992

Impairment of endothelium dependent responses in a rat model of chronic heart failure: effects of an exercise training protocol.

OBJECTIVE: The aim was to document the response of aortic rings from a rat model of heart failure to endothelium dependent and endothelium independent vasodilating agents. The effects of an exercise training schedule upon these responses was studied. METHODS: Heart failure was produced in one group of female Wistar rats by coronary artery occlusion, and sham operations were performed in a matched group. The rats were allowed to recover for six weeks, following which half the rats with heart failure were started on a treadmill exercise schedule for a further six weeks. After this time the rats were killed, and rings of aorta were studied in an organ bath to measure the response to both endothelium dependent and endothelium independent vasoactive agents. RESULTS: The presence of heart failure was confirmed in both the non-trained (NT, n = 5) and trained rats (TR, n = 5), but not in the sham operated animals (SH, n = 6). The constrictor response to prostaglandin F2 alpha was similar in aortic rings from all the animals. The relaxation response to the endothelium dependent vasodilator acetylcholine (10(-7) and 10(-6) M) was impaired in the rats with heart failure compared to the sham operated animals (10% v 33% with 10(-7) M acetylcholine, p < 0.005). The dilator response in the trained rats was not significantly greater than in the non-trained rats (TR 35% v NT 24% with 10(-6) M acetylcholine). There was no difference in the response to sodium nitroprusside (10(-7) and 10(-6) M) between the three groups. CONCLUSIONS: Chronic heart failure impairs the response of aortic rings to the endothelium dependent vasodilator acetylcholine in a rat model of heart failure. The response to sodium nitroprusside, an endothelium independent relaxing agent, is not impaired by heart failure. These findings may help to explain the raised systemic vascular resistance and the failure of vasodilatation in skeletal muscle vasculature which limits exercise capacity in subjects with heart failure.

Acetylcholine↗
PubMed1992

Nuclear magnetic resonance spectroscopy of excised human hearts.

BACKGROUND: Phosphorus nuclear magnetic resonance spectroscopy has been proposed as a method of studying the metabolism of the myocardium in patients. Little is known about 31P nuclear magnetic resonance spectroscopy of diseased human hearts. METHODS: Two donor hearts meeting the requirements for heart transplantation and 11 diseased hearts were removed during a transplantation procedure and were studied in a horizontal 2.35 T superconducting magnet. Spectra were obtained at 0 degrees C about 30 minutes after the excision. The areas of the inorganic phosphate peak (Pi) and of the phosphocreatine peak (PCr) were summed and expressed as a ratio with respect to the area of the beta ATP peak. RESULTS: The ratio (Pi + PCr)/beta ATP was found to be significantly lower in five hearts with a myocardial infarct (0.77 (0.18)) than in hearts with dilated cardiomyopathy (1.25 (0.29)) and in normal hearts (1.69 (0.11)). The area of the phosphodiester peak was expressed as a ratio with respect to the area of the beta ATP peak: no differences were found between the three groups. CONCLUSIONS: These results suggest that the phosphocreatine concentration is lower in ischaemic heart disease than in dilated cardiomyopathy and that the phosphodiester peak is probably not useful in distinguishing between these two types of heart disease.

Adenosine Triphosphate↗
PubMed1992

Energetic metabolism in hypothyroid skeletal muscle, as studied by phosphorus magnetic resonance spectroscopy.

Phosphorus nuclear magnetic resonance spectroscopy was used to investigate the muscle bioenergetics in different hypothyroid states. Using the thenar muscle group as reference, 2 patients with chronic and severe hormonal deficiency, 3 patients with subacute hypothyroidism, and 8 patients with moderate thyroid insufficiency with isolated high blood TSH levels were studied at rest, during exercise, and during subsequent recovery. The patients were compared with 15 control subjects. Only 1 patient presented a clinical myopathy. The intracellular pH and the relative measurements of inorganic phosphate, phosphocreatine, phosphodiesters, and ATP were directly calculated from phosphorus spectra. Resting muscle showed a significant rise in the inorganic phosphate to ATP ratio. In working hypothyroid muscle, a more important decrease in phosphocreatine levels was noted in patients with chronic and subacute thyroid deficiency, while the intracellular pH fall was greater in all hypothyroid patients than in control subjects. The phosphocreatine recovery rate was lower in all deficient patients, reflecting a probable mitochondrial metabolism impairment. These results are consistent with a defect of the high energy phosphate metabolism in hypothyroidism, even in moderate or recent hormonal deficiency.

Adenosine Triphosphate↗
PubMed1991

The effect of beta 2-adrenoceptor stimulation and blockade of L-type calcium channels on in vivo Na+/H+ antiporter activity in rat skeletal muscle.

We have studied the in vivo response of the Na+/H+ antiporter in skeletal muscle to beta 2-adrenoceptor stimulation with isoprenaline and the effect of blocking L-type calcium channels with nifedipine. Na+/H+ antiporter activity in skeletal muscle in vivo increased after beta 2-adrenoceptor stimulation with isoprenaline; nifedipine attenuated that effect. This suggests that opening of L-type calcium channels is necessary for full activation of the Na+/H+ antiporter in skeletal muscle. Bleeding also increased Na/H+ antiporter activity, which we believe could be explained by an increase in sympathetic nervous system activity as a result of hypotension. This may be one of the mechanisms by which animals under stress prepare their skeletal muscle for exercise as part of the 'fright and flight' reaction.

Adenosine Triphosphate↗
PubMed1991

Migraine in patients with history of centro-temporal epilepsy in childhood: a Hm-PAO SPECT study.

The authors report the results of a retrospective controlled study on the incidence of migraine in centro-temporal epilepsy compared to absence epilepsy, partial epilepsy and a group of patients with cranial trauma without epilepsy. The following observations from this series of 129 patients were made. Migraine was present in 63% of the patients with centro-temporal epilepsy (rolandic epilepsy), in 33% with absence epilepsy, in 7% with partial epilepsy and in 9% of the cranial trauma group. These results suggest that the association of centro-temporal epilepsy and migraine is non-fortuitous and also to a lesser degree in absence epilepsy. The role of neurotransmitters in this association is discussed. No decrease in cerebral blood flow was observed in 12 patients with rolandic epilepsy on a Hm-PAO SPECT study.

Adolescent↗
PubMed1991

31P-NMR study of different hypothyroid states in rat leg muscle.

Using phosphorus nuclear magnetic resonance spectroscopy, this study was undertaken to determine the effects of experimental hypothyroidism on muscle bioenergetics. The peaks of phosphocreatine (PCr), Pi, phosphodiesters (PDE), sugar phosphomonoesters, and ATP were obtained at rest, during a 2-Hz hindleg muscle stimulation, and during a subsequent recovery period from four groups of anesthetized rats as follows: one control and three hypothyroid (HT) groups treated by propylthyouracil during 2, 4, and 6 wk, respectively. Resting spectra showed a significant rise in Pi by 30% and decreased intracellular pH and PCr/Pi in all three HT groups. PDE progressively increased to 200% of its initial value with hypothyroidism duration. Muscle stimulation did not lead to significant differences in PCr depletion. The percentage of PCr recovery is less in HT muscle than in control muscle. An abnormal H+ metabolism is obvious in all three HT groups. These results indicate abnormal bioenergetics in HT muscle and suggest an impairment of mitochondrial metabolism and of the H+ efflux. They also evoke a high sensitivity of cellular energetics to thyroid deficiency.

Animals↗
PubMed1991

Muscle bioenergetic impairment in hyperthyroid man: a study by 31P NMR spectroscopy.

Phosphorus nuclear magnetic resonance spectroscopy was used to investigate muscle bioenergetics in 9 hyperthyroid patients who were compared with 9 normal subjects. Using the thenar muscle group as reference, the inorganic phosphate, phosphocreatine and intracellular pH were calculated at rest, during aerobic exercise (0.13 w) and post-exercise recovery. No difference was found at rest. After 5 min of exercise, the hyperthyroid patients exhibited a more important phosphocreatine depletion (41.2 +/- 8.2 vs 31.1% +/- 6.5, p less than 0.02) and a larger pH fall (6.65 +/- 0.04 vs 7.01 +/- 0.10, p less than 0.001) than the control subjects. The phosphocreatine recovery rate was not significantly different in hyperthyroid patients and control subjects. These results suggest that exercise requires more ATP in hyperthyroid patients than in normal subjects and that there is excessive dependence on glycolytic metabolism for ATP synthesis in hyperthyroidism. Phosphocreatine resynthesis, reflecting the oxidative metabolism, is not increased. These metabolic disturbances could also supply a partial explanation to the frequent exercise intolerance in hyperthyroid patients.

Adenosine Triphosphate↗
PubMed1991

[Effects of fibrinolysis on late potentials in myocardial infarction].

Late potentials are an index of gravity following myocardial infarction, but there has been little investigation of the effects of fibrinolysis on their incidence. Eighty-two consecutive patients (68 men, 14 women, group men age = 55 +/- 8 years) admitted presenting with a primary infarction and who had received fibrinolytic treatment within the first four hours. Each patient was screened for late potentials, and underwent a coronary artery angiograph and determination of the left ventricular ejaculation fraction (LCEF) following the infarction. The incidence of late potentials was 38% in the patients with an occluded coronary artery (9/24) vs 12% in patients with a permeable artery (7/58) (p less than 0.02). The change in LVEF was greater if reperfusion was not achieved (47 +/- 13% vs 54 +/- 12%, p less than 0.05). This study suggests that following fibrinolysis, the incidence of late potentials is correlated with both an absence of coronary reperfusion and deterioration of left ventricular function.

Adult↗
PubMed1991

[Factors influencing the occurrence of delayed potentials after myocardial infarction. A multivariate study].

Delayed or late potentials after myocardial infarction is a marker of the risk of severe ventricular arrhythmias. We looked for the factors favorising the appearance of these potentials in 208 consecutive patients (172 men, 36 women) admitted to hospital for primary myocardial infarction. Coronary angiography, evaluation of the left ventricular ejection fraction and signal averaged electrocardiography were performed in all patients who were then divided into two groups (Group I: patients with delayed potentials; Group II: patients without delayed potentials). A multivariate analysis of 7 different clinical and paraclinical parameters possibly related to delayed potentials was undertaken. The overall incidence of delayed potentials was 20%. The coronary artery responsible for the infarct was occluded in 79% of patients in Group I and 31% of patients in Group II (p less than 0.00009). The left ventricular ejection fraction was significantly lower in Group I (45.9% vs 54.5%, p less than 0.0002). The incidence of anterior infarcts was 58% in Group I and 37% in Group II (p = 0.008). These 3 factors were independent and correlated with the presence of delayed potentials. The multivariate analysis showed that the major factor was coronary occlusion with presence of delayed potentials multiplied by 6.3, whereas anterior infarction multiplied the risk of delayed potentials by 2.6 and each 10% decrease in LV ejection fraction increased the risk by 1.4.

Action Potentials↗
PubMed1990

[Phosphorus NMR spectroscopy. Its value in the diagnosis of metabolic myopathies. A case of Mac Ardle's disease].

Phosphorus nuclear magnetic resonance spectroscopy is a non-invasive method used to study muscle bioenergetics in vivo. A new case of Mc Ardle's disease (myophosphorylase deficiency) is reported here. In a context of metabolic myopathy this method can provide a diagnosis of glycogenosis. The spectra obtained at exercise and during recovery determine the degree of enzyme deficiency with satisfactory precision.

Adult↗
PubMed1990

Improved subtraction technique in intravenous digital left ventriculography: comparison with radionuclide studies.

Adequate processing of left ventricular angiograms depends on the visualisation of all segments of the ventricular wall. At the same time, subtraction of different images can enhance different heart segments but commercially available methods do not allow simultaneous viewing of several images masked by different processes. Using our software, for each studied frame, a four quadrant display permits the simultaneous visualisation of a mask mode image, a diastolic-systolic difference image, an image obtained by subtraction of a frame at the same cycle time and a composite mask subtracted image. The composite mask image is obtained by weighting three images according to videodensitometric measurements by reference to previously acquired data. This method facilitates contour delineation and computation of the ejection fraction by area-length method. Correlation with radionuclide estimates of left ventricular ejection fraction is higher (n = 60, r = 0.90, SEE = 8%) than using the classical mask mode display (n = 60, r = 0.82, SEE = 11%). In a subgroup of 30 patients the contrast medium was injected in an antecubital vein and the correlation coefficient remained satisfactory (n = 30, r = 0.89, SEE = 7%) when compared with the classical subtraction technique (n = 30, r = 0.70, SEE = 12%). We therefore conclude that the composite mask method gives comparatively similar values for left ventricular ejection fraction to those acquired by radionuclide angiography.

Angiography, Digital Subtraction↗
PubMed1990

Effects of iron-binding proteins on in vitro uptake of 67Ga-citrate by tumor cells.

A comparative study of carrier-free 67Ga-citrate uptake by Ehrlich ascites tumor cells in the presence of lactoferrin, transferrin and ferritin has demonstrated that lactoferrin considerably increases the uptake of 67Ga, and that this increase seems to be determined by its iron-load. The other iron-binding proteins assayed have a null or negative effect. Their behavior in the presence of sodium citrate supports the concept of lactoferrin-binding by the cells as responsible for the uptake. The different behavior of 67Ga-citrate iron-binding protein complexes appears to support this hypothesis.

Animals↗
PubMed1990

Skeletal muscle metabolism in the leg during exercise in patients with congestive heart failure.

1. Using 31P nuclear magnetic resonance, it has previously been demonstrated that patients with congestive heart failure exhibit a greater than normal phosphocreatine (PCr) depletion in the working skeletal muscles of the arm. We have studied the importance of the work necessary to reach a similar PCr depletion ([PCr]/([PCr] + [Pi]) = 0.5) in calf muscle. Our results show significantly lower values for patients with congestive heart failure in both aerobic and ischaemic conditions (respectively: 0.009 +/- 0.007 vs 0.026 +/- 0.013 W/kg body weight, P less than 0.01; 0.29 +/- 0.16 vs 0.90 +/- 0.25 J/kg body weight, P less than 0.01). 2. This original model of skeletal muscle exercise facilitates a comparison of PCr recovery rate due to a similarity in the PCr depletion and intracellular pH in the two series at the start of recovery. However, the PCr recovery rate is similar after both normoxic and ischaemic exercise, i.e. respective percentages of PCr increase in the first 25 s recovery spectrum were: (a) aerobic exercise, congestive heart failure 133 +/- 18%, control series 138 +/- 18%; (b) ischaemic exercise, congestive heart failure 114 +/- 13%, control series 118 +/- 12%. The absence of a difference in PCr recovery rate and the greater PCr depletion by ischaemic work in patients with congestive heart failure suggest modifications that cannot be explained by a reduced blood flow to the muscle. 3. When comparing the two series, intracellular pH evolved similarly in normoxia and ischaemia during both work and recovery. Thus, no increase in anaerobic glycolytic activity appears when equivalent PCr depletion has occurred.

Adult↗