[Radionuclide ejection fraction at rest and in exercise in chronic aortic insufficiency. Pre- and postoperative study in asymptomatic or paucisymptomatic patients]. / Fraction d'éjection isotopique du ventricle gauche au repos et à l'effort dans l'insuffisance aortique chronique. Etude pré- et postopératoire chez les patients a- ou paucisymptomatiques.

Twenty patients (17 men and 3 women: average age 50 +/- 14 years) with asymptomatic or paucisymptomatic aortic regurgitation were studied to compare the values of radionuclide left ventricular ejection fraction (EF) at rest and on exercise before (1) and 6 +/- 1 months (2) and 5.7 +/- 1.1 years (3) after surgery. The resting EF was similar at all three examinations: 53 +/- 8 (1); 57 +/- 8 (2); 55 +/- 16 (3). However, it increased significantly on exercise from 40 +/- 10 (1) to 54 +/- 12 (2) (p < 0.001) and to 52 +/- 20 (3) (p = 0.036 versus 1). In the 7 patients with resting EF greater than 55 before surgery, there was no postoperative improvement: 61 +/- 6 (1); 61 +/- 5 (2); 65 +/- 9 (3). However, the exercise EF increased from 44 +/- 13 (1) to 55 +/- 17 (2) and 69 +/- 11 (3) (p = 0.004 vs 1). In 13 patients with resting EF < 55%, the value increased in the early postoperative phase but not later: resting: 49 +/- 5 (1); 55 +/- 8 (2) (p = 0.04); 49 +/- 17 (3) (NS vs 1); effort: 38 +/- 7 (1); 54 +/- 10 (2) (p < 0.001); 40 +/- 16 (3) (NS vs 1). Left ventricular systolic function only returns to normal and exercise after surgery in patients with resting preoperative EF > or = 55%, but nothing indicates that this normalisation is an absolute condition for a successful surgical result in aortic insufficiency in terms of survival and quality of life.

[Value of the positive exercise test without angina (after myocardial infarct)]. / Valeur de l'épreuve d'effort positive sans angor (après infarctus du myocarde).

In order to determine the value of a positive exercise test (ET) (i.e. ischaemic ST depression) without chest pain observed after a myocardial infarction (MI), 102 ET's were reviewed. ET was performed without anti-ischaemic drugs. The mean time-lag between MI and ET was 51 +/- 55 months. The MI was inferior in 26 cases, inferior and/or posterior in 74 cases and of undetermined location in 2 cases. Thirty patients had both ST depression and chest pain (group 1); 35 had electrocardiographic signs of ischaemia without pain (group 2), and 37 had neither chest pain nor signs of ischaemia (group 3). Age, sex ratio, site of infarction and time-lag between MI and ET were similar in all three groups. The post-ET follow-up period was 33 +/- 18 months (range: 6 to 66 months); 2 patients in group 3 were lost sight of. There was no significant difference between groups 1 and 2 as regards total duration of ET, workload attained, heart rate, systolic arterial pressure, pressure-rate product and amplitude of ST depression at maximum exercise level. Group 3 differed from the other 2 groups in workload attained (p less than 0.05) and in pressure-rate product (p less than 0.05 vs group 1, p less than 0.01 vs group 2). There was no significant difference between groups 1 and 2 as regards post-ET events (recurrent angina, reinfarction, coronary bypass, transluminal angioplasty).(ABSTRACT TRUNCATED AT 250 WORDS)

[Course of the radionuclide left ventricular ejection fraction at rest and during exercise in surgically treated asymptomatic chronic aortic insufficiency]. / Evolution de la fraction d'éjection radio-isotopique ventriculaire gauche au repos et á l'effort dans l'insuffisance aortique chronique asymptomatique opérée.

In order to preserve left ventricular (LV) function, aortic valve replacement may be contemplated in asymptomatic patients with aortic regurgitation when LV dilatation and dysfunction are not too advanced. Our study involved 10 asymptomatic patients with severe, isolated and pure aortic regurgitation. Before, and 6 months after the operation, the LV ejection fraction (LVEF) was measured at rest and during exercise on an ergometric bicycle by radionuclide angiography (multigated technique). Mean preoperative values were: age 52 +/- 14 years; cardiothoracic ratio 0.55 +/- 0.04; end-diastolic LV diameter 69 +/- 9 mm; end systolic LV diameter 47 +/- 7 mm; LV fibre shortening fraction 0.31 +/- 0.03; LVEF 0.55 +/- 0.10 at rest and 0.41 +/- 0.13 at exercise. After surgery, the cardiothoracic ratio value (0.51 +/- 0.03) and the LVEF value at rest (0.60 +/- 0.07) were not significantly different from the corresponding preoperative values, but the LVEF value during exercise was significantly increased (0.58 +/- 0.11, p less than 0.001). Among the 9 patients who before surgery showed a fall in LVEF at exercise, after surgery 5 had a rise (group B) and 4 had a fall (group A) in LVEF at exercise. Before surgery, group A patients had greater LV diameters than group B patients: end-diastolic diameter 76 +/- 6 mm vs 63 +/- 9 mm; end-systolic diameter 53 +/- 4 mm vs 43 +/- 7 mm (p = 0.07). These diameters were the only variables that predicted the postoperative changes in LVEF at exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

[Enalapril versus digoxin in chronic congestive cardiac failure. Study of variation of the left ventricular ejection fraction determined by radio-isotopic angioscintigraphy at rest and during exertion]. / Enalapril versus digoxine dans l'insuffisance cardiaque chronique congestive. Etude de la variation de la fraction d'éjection ventriculaire gauche déterminée par angioscintigraphie radio-isotopique au repos et à l'effort.

The effects of enalapril were evaluated in a double-blind, controlled study during 8 weeks, in patients with stable, congestive chronic cardiac insufficiency (functional classification II and III of the NYHA), in sinus rhythm, treated with digitalis and diuretics. 20 patients were randomly divided in two groups: one group continuing the digoxin (group A: 10 patients) and one group where enalapril was substituted for digoxin (group B: 10 patients). Patients from group B presented less clinical aggravation during the study. The left ventricular stroke volume (SV) is significantly decreased in group B at rest (0.21 +/- 0.06 at 50; 0.18 +/- 0.04 at 54; p less than 0.05), while it remained stable during stress. No variations of the SVs were noted at rest and during stress in group A. Considering its favorable clinical effects and after evaluation of its longterm side effects, enalapril may be an acceptable alternative to digitalis in cardiac insufficiency with sinus rhythm, except in patients for whom a drop in the systemic blood pressure or an increased kaliemia or creatininemia, could be potentially harmful.

[Left ventricular function in chronic asymptomatic aortic insufficiency. Angioscintographic study]. / Fonction ventriculaire gauche dans l'insuffisance aortique chronique asymptomatique. Etude par angioscintigraphie.

More accurate information is needed on the usefulness of radionuclide angiography performed during exercise for the assessment of left ventricular function in chronic aortic regurgitation and on its value compared with echocardiography. Between January, 1985 and January, 1988, we studied 23 asymptomatic patients presenting with severe, isolated and pure aortic regurgitation. Nine patients who were not operated upon during that period (group N) had the following characteristics: age 39.4 +/- 12.3 years, left ventricular end-diastolic diameter 67.3 +/- 4.7 mm, left ventricular end-systolic diameter 43.4 +/- 3.2 mm, left ventricular fibre shortening fraction 0.36 +/- 0.05, left ventricular radionuclide ejection fraction 0.67 +/- 0.10 at rest and 0.66 +/- 0.09 during maximum exercise. Compared with the values obtained in 8 controls of the same age (ejection fraction 0.65 +/- 0.07, p less than 0.05, at rest and 0.76 +/- 0.09, p less than 0.05, during maximum exercise), the behaviour of group N patients during exercise was perturbed. Fourteen patients who underwent surgery presented with the following characteristics: age 53.3 +/- 13.3 years (p less than 0.05), left ventricular end-diastolic diameter 71.4 +/- 8.7 mm (p less than 0.05), left ventricular end-systolic diameter 49.4 +/- 6.5 mm (p less than 0.05), fibre shortening fraction 0.31 +/- 0.03 (p less than 0.01), ejection fraction 0.53 +/- 0.08 at rest (p less than 0.001) and 0.40 +/- 0.08 during maximum exercise (p less than 0.001). These results suggest that radionuclide angiography performed during exercise is effective in the early detection and accurate evaluation of myocardial dysfunction in patients with chronic aortic regurgitation at the asymptomatic stage.(ABSTRACT TRUNCATED AT 250 WORDS)

The choice of the wavelengths in spectral analysis: an application to determine the composition of a tetraribonucleotide mixture.

We present a simple program running on a pocket computer allowing us to determine the order of importance of the wavelengths (regarding the accuracy of the results) in spectral analysis and to evaluate the absolute errors made on the determination of the concentrations of the constituents. We have applied this programme to the determination of the composition of a tetraribonucleotide mixture and have compared our results with other results published.

Optimization of the determination of RNA nucleotide composition by ultraviolet spectral analysis.

We have optimized the spectrophotometric method for the quantitative analysis of a tetranucleotide mixture (for example an RNA hydrolysate) by carefully choosing the wavelengths and the pH at which the absorbance measurements were made, and estimated the error made on the calculated concentration of each nucleotide. The most convenient method involved the measurement of only four absorbances (at 228 nm at pH 13; 200, 212 and 284 nm at pH 2). If the sensitivity of the spectrophotometer is 0.001 unit absorbance, the absolute error made on the calculated percentage of each nucleotide is lower than 0.33%.

[Quantitative analysis of a tetraribonucleotide mixture by ultraviolet spectrophotometry]. / Analyse quantitative d'un mélange tétraribonucléotidique par spectrophotométrie dans l'ultraviolet.

Using the least squares method we have calculated the proportions of each nucleotide of a mixture of AMP, CMP, GMP and UMP, after measuring the absorbance of the mixture every ten nanometers from 230 to 290 nm at pH 12.7 and 2. The method is very simple and rapid (the calculations are made in less than one minute), does not require a highly sensitive spectrophotometer to obtain reasonably precise results and, in contrast to the other methods of the literature, it can be applied to quantities as little as 50 micrograms of nucleotides.

[Simple method for preparation of rat liver DNA]. / Technique simple de préparation des acides désoxyribonucléiques de foie de rat.

The frozen tissue was sliced and then homogenized at 20 degree C in LiCl, 2 M; lauryl-trimethyl ammonium chloride (K & K No. 4484), 5%; pronase, B grade (calbiochem), 1 mg/ml and Tris-HCl 10 mM pH 7.5. The homogenate was left to stand 15 min at 20 degree C with occasional shaking. After centrifugation at 35 000 X g for 30 min at 0 degree C, the supernatant containing the crude DNA was purified by filtration on Ultrogel A 2 (LKB, Sweden). The Ultrogel A 2 column (2.5 X 45 cm) was equilibrated with a solution containing NaCl 2 M, EDTA 2.5 mM, Tris-HCl 10 mM pH 7.5. The flow rate was 3 ml cm-2 h-1. Five ml of the supernatant were placed on the column. The first peak contained highly polymerized (as demonstrated by ultracentrifugation) pure DNA (A260/A230 = 3.19; A260/A280 = 1.82). The yield was 2.26 mg of DNA/g of fresh liver.