Left ventricle automated detection method in gated isotopic ventriculography using fuzzy clustering.

A method that uses the fuzzy ISODATA clustering algorithm and Fourier analysis is proposed for automated detection of heart left ventricle contours. This operation is used for quantitative analysis of cardiac function. The computation begins by finding the phase image. The fuzzy ISODATA algorithm is first applied to this image to generate a number of clusters that correspond to the organ substructures (ventricles, atria). Second, the ventricles cluster is isolated and the intensities of its points are replaced by the corresponding ones from the original (end diastolic) frame. Finally, a reduced image representing the ventricular region is obtained and an additional clustering is performed to find the left ventricular boundary automatically. This algorithm is tested by application of 105 sets of 16 images each. These results are compared with the measurements obtained with two semi-automatic methods used, respectively, on the Philips and the Sopha Medical gamma cameras.

Automated detection of the left ventricular region in gated nuclear cardiac imaging.

An approach to automated outlining the left ventricular contour and its bounded area in gated isotopic ventriculography is proposed. Its purpose is to determine the ejection fraction (EF), an important parameter for measuring cardiac function. The method uses a modified version of the fuzzy C-means (MFCM) algorithm and a labeling technique. The MFCM algorithm is applied to the end diastolic (ED) frame and then the (FCM) is applied to the remaining images in a "box" of interest. The MFCM generates a number of fuzzy clusters. Each cluster is a substructure of the heart (left ventricle,...). A cluster validity index to estimate the optimum clusters number present in image data point is used. This index takes account of the homogeneity in each cluster and is connected to the geometrical property of data set. The labeling is only performed to achieve the detection process in the ED frame. Since the left ventricle (LV) cluster has the greatest area of the cardiac images sequence in ED phase, a framing operation is performed to obtain, automatically, the "box" enclosing the LV cluster. THe EF assessed in 50 patients by the proposed method and a semi-automatic one, routinely used, are presented. A good correlation between the two methods EF values is obtained (R = 0.93). The LV contour found has been judged very satisfactory by a team of trained clinicians.

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%.

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.

[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)

[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)

[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.

[Preparation of giant RNA from bovine thyroid gland by agarose gel filtration]. / Préparation des RNA géants de la glande thyroïde de boeuf par filtration sur gel d' agarose.

Giant RNA's were prepared by a rapid gel-filtration technique. DNAase, pronase and thyroid homogenate were successively placed on the column. Proteins and DNA were degraded during filtration. Void volume contained pure giant RNA's. Giant RNAs' yield was 7 times higher with this method than with phenol method.

[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.

[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.

[Rapid technic for preparation of thyroid ribonucleic acids without phenol]. / Technique rapide de preparation des acides ribonucleiques thyroidiens sans phenol.

Thyroid tissue was homogenized in 2 M LiCl. The homogenate was alloued to stand 1 h 30 min at 2 degrees C and then centrifuged. The pellet was suspended in 5% triisopropylnaphthalene sulfonic acid (the sodium salt), 0.05 M Tris--HCl, and 0.1 M NaCl (pH 8). After stirring and centrifuging, the supernatant containing the crude RNA was purified by filtration on Ultrogel AcA 22 (LKB, Sweden). Before adding the sample of crude RNA to the column, pronase was placed on the column. When pronase had entered the gel, we added the sample. The first peak contained pure RNA plus some DNA. The former was precipitated with 2 M LiCl. The RNA species obtained by this technique were undegraded and the yield was 30% better than that of the phenol technique.

[Isolation and characterization of beef thyroid giant RNA]. / Isolement et caractérisation des RNA géants de la glande thyroide de boeuf.

Total HMW-RNAs were prepared by three different methods (method with phenol, method with NaClO4, method without phenol using Ultrogel AcA 22 filtration). Giant RNAs were obtained in the void volume by filtration on Sepharose 2B. The giant RNAs/total HMW-RNA ratio is higher (6.77%) with the gel filtration method than with phenol or NaClO4 methods (1.41% and 1.00% respectively). The nucleotide composition of these RNAs is DNA-like and the sedimentation constants are approximately 70-100 S.

Ribosomal and transfer RNA contents of the normal and pathologic human thyroid gland.

One hundred and seventy seven pieces of normal or pathologic thyroid tissue from 17 patients were assayed for rRNA, tRNA and DNA content. The tRNA/DNA and rRNA/DNA ratios in pathologic tissue were statistically compared with the same ratios in normal tissue. In toxic adenoma (5 cases) and anoplastic cancer (2 cases), both ratios were increased. In cold nodules (9 cases), there was in increase of the tRNA/DNA ratio only in 1 case, of the rRNA/DNA ratio only in 4 cases, and of both ratios in 3 cases. In one case of a cold nodule in a Basedow's disease gland, there was no modification of these ratios. In Basedow's disease (3 cases), there was an increase of rRNA/DNA ratio only in one case.