Raman spectroscopy and WAXS method as a tool for analysing ion-exchange properties of alginate hydrogels.

Hydrogels are cross-linked three-dimensional macromolecular networks that contain a large fraction of water within their structure. One of the most important properties of alginate hydrogels, leading to their broad versatility, is their ability for controlled uptake, release and retention of molecules. This ability, in turn, is due to specific interactions of the macromolecular network with the diffusing or retained molecule. Raman spectroscopy has been employed to characterize the diffusion properties of solutes in hydrogels. Besides their application in the food sector, they are used in many biomedical, pharmaceutical and technical areas; for example, as a natural tissue or drug carriers. In the latter case, controlled release of drugs from a wound dressing is of particular interest-or ion exchange between the drug and the structure of the dressing. Raman active vibrations were used to show the areas responsible for the penetration of the model azo-dyes (based on non-genotoxic benzidine analogs) within Ca-alginate/carboxymethylcellulose Medisorb A wound dressing. In this case, the intensity of the stretching bands was used to obtain the concentration profiles of the model dye in alginate/carboxymethylcellulose gel (Medisorb A). The characteristic band at 1511 cm(-1) indicates that new band positions were observed following dye adsorption on wound dressing. The Raman spectra of alginate immersed for different times in Ringer's solution reveal peak shifts. Differences in peak shapes and the appearance of new bands are observed as the sodium content increased. Raman spectra give direct information on the exchange process. There are also new peaks appearing at 1034-1016 and 850 cm(-1) regions in the spectra after the release studies. This could, therefore, correspond to a partial bonding between sodium and oxygen atoms (the guluronic units originate a band at approximately 1025 cm(-1)). The aim of the examination in this paper also was to investigate the crystallinity index of Medisorb A wound dressing dyed (or undyed) and Medisorb A wound dressing after the release process in Ringer's solution (the crystallinity index is about 65%). In WAXS curves we can observed additional peaks (2theta at 32 degrees and 45 degrees ).

[Long-term effects of indapamide in left ventricular hypertrophy in patients with hypertension]. / Effets à long terme de l'indapamide sur l'hypertrophie ventriculaire gauche de l'hypertendu.

Left ventricular hypertrophy is a major and independent cardiovascular risk factor in hypertension. The effects of a diuretic, indapamide, on the regression of left ventricular hypertrophy were studied in a group of 9 patients with mild hypertension treated in an open therapeutic trial over a 12 month period. At the end of the trial, the left ventricular mass index decreased significantly from 172 +/- 11 to 147 +/- 11 g/m2 (p less than 0.001). Therefore, in contrast to the other diuretics which have been studied, indapamide seems able to induce regression of the left ventricular hypertrophy complicating hypertension.

Effects of indapamide on left ventricular mass and function in systemic hypertension with left ventricular hypertrophy.

Left ventricular hypertrophy (LVH) is frequently associated with hypertension and constitutes a major cardiovascular risk factor, the reduction of which should be considered when initiating antihypertensive therapy. To assess the effects of indapamide on LVH, 18 hypertensive patients were included in the study (11 men and 7 women, age 53.6 +/- 2.9 years, mean +/- standard deviation) whose supine diastolic blood pressure was greater than 95 mm Hg without (n = 11) or with (n = 7:6 beta blockers, 1 calcium antagonist) antihypertensive therapy. All presented with LVH, echocardiographically defined by a left ventricular mass index greater than 110 g/m2. After a 2-week preinclusion period, all patients received indapamide, 2.5 mg/day, for a period of 6 months. Physical examination including blood pressure measurement was performed on selection (M-1/2), before (M0), and after 1 (M1), 3 (M3) and 6 (M6) months of indapamide treatment, and echocardiography was performed at M0 and M6. Quality of life was evaluated by means of questionnaires completed by the patient and the physician, and a visual analog scale was completed by the patient at M-1/2, M0 and M6. All clinical parameters remained stable during the 2-week preinclusion period. Indapamide administration induced a highly significant reduction in both supine systolic and diastolic blood pressures from 173.9 +/- 2.9/100.5 +/- 1.2 mm Hg at M0 to 150.9 +/- 1.9/90.5 +/- 1.3 mm Hg at M1 (p less than 0.001), and 145.0 +/- 1.7/86.0 +/- 1.5 mm Hg at M6 (p less than 0.001). Similar favorable effects were observed in the upright position.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive study of dual chamber pacing by pulsed Doppler. Prediction of the haemodynamic response by echocardiographic measurements.

The increase in stroke volume with DDD compared with VVI pacing was measured at rest using pulsed Doppler echocardiography in 23 patients at a pacing rate of 70 beats min-1. Stroke volume was assessed by measuring the velocity integral of the flow at the aortic annulus using the apical five-chamber window. Pulsed Doppler echocardiography allowed determination of the least and most favourable AV delay haemodynamically. TVI was also measured at each nominal value of AV delay. The percentage increase in stroke volume was determined in every patient changing from VVI to optimum DDD pacing and was used as a measurement of the 'sensitivity' to optimum DDD pacing; the mean increase was 27 +/- 19%. The increase in stroke volume accompanying the change from DDD pacing with the least favourable to the optimum AV delay was also measured, and used as a measurement of 'sensitivity' to changes in AV delay; the mean increase was 23.7 +/- 16.3%. Clinical and standard echocardiographic parameters were studied in order to determine which variable might best identify the patients more likely to benefit from DDD pacing, and to identify those more sensitive to the AV delay setting. With respect to sensitivity to DDD pacing, three echocardiographic variables were selected by linear discriminant analysis from 11 clinical and echocardiographic variables. These were, in order of importance, left ventricular systolic diameter (LVSD), left ventricular wall thickness (LVWT) and left atrial size (LAS) which allowed the prediction of a good or a bad response to optimal DDD pacing with an accuracy of 91.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

[Doppler ultrasound evaluation of aortic insufficiency using half-pressure time. Absence of arterial rigidity influence]. / Evaluation doppler de l'insuffisance aortique par le temps de demi-pression. Absence d'influence de la rigidité artérielle.

In 20 patients with pure aortic regurgitation we studied the relationship between the severity of regurgitation, as assessed haemodynamically by the percentage of leakage (%L), and the half-pressure (T 1/2 P) and half-velocity (T 1/2 V) times, as obtained from doppler aortic blood velocity curves, taking into account the rigidity of the systemic vascular circuit characterized by the pressure wave propagation velocity (PWPV). The systemic arterial circuit was supple in 14 patients (PWPV less than 7.5 m/sec) and rigid in 6 patients (PWPV greater than 7.5 m/sec). The regression slopes between %L and T 1/2 P and between %L and T 1/2 V were calculated with their confidence limits in the 14 patients with supple arteries. The 6 patients with rigid arteries fitted into this nomogram, thus demonstrating that systemic arterial rigidity makes no difference in the relationship between %L and doppler indices. The half-velocity and half-pressure times measured by doppler ultrasound were acquired from a velocity signal directly determined by the aortic regurgitation, without any detectable effect of vascular circuit rigidity. Being equivalent by nature to the signal decrease time constant, they are independent of the absolute protodiastolic value of diastolic pressure gradient or blood flow velocity. For this reason these two doppler parameters are reliable to evaluate the severity of aortic regurgitation.

[Criteria of selection of mitral valve prolapse truly pathological]. / Critères de sélection du prolapsus valvulaire mitral réellement pathologique.

Considering the high frequency of mitral valve prolapse in the general population and the frequent errors concerning its diagnosis, we have attempted to select a few criteria in order to differentiate the forms which are really pathological. This selection, in light of the data from the literature, is based on the clinical context and ultrasound results.

[Echocardiographic diagnosis of plurivalvular prolapse. Apropos of a case]. / Diagnostic échocardiographique des prolapsus plurivalvulaires. A propos d'une observation.

Sonocardiography, especially bi-dimensional, currently represents an examination of choice in the detection of valvular prolapses. The authors report one case of a triple aorto-mitral-tricuspid valvular prolapse, diagnosed with the ultrasound technique. In light of this report and the data from the literature, the frequency and the distribution of valvular affections are discussed. The technical difficulties of recording and interpreting sonographic images responsible for false positive or false negative diagnostic errors are also studied.

[Echographic evaluation of the severity of aortic stenosis in cases with associated mitral stenosis]. / Appréciation échographique de la sévérité du rétrécissement aortique en cas de sténose mitrale associée.

The echocardiographic findings of six patients with pure mitral stenosis associated with pure aortic stenosis were compared with the findings from a series of ten cases of pure aortic stenosis without mitral disease. Each patient also underwent haemodynamic studies in order to quantitate the severity of the stenoses. The aortic stenosis was of the same degree of severity in both series (0.71 +/- 0.24 cm2 and 0.73 +/- 0.16 cm2). The systolic separation of the aortic valve was greater than 1 cm in 4 of the 6 cases on echocardiography, corresponding to a false negative of tight aortic stenosis. This appearance corresponded to a doming of the aortic valve on 2D echocardiography. The wall thickness was significantly less in the AS + MS series than in pure SA series (1.13 +/- 0.13 cm compared with 1.52 +/- 0.21 cm; p less than 0.01). The wall was found to be thicker, the tighter the MS. Overall, the diagnostic criteria of the severity of AS on echocardiography (restricted opening of the valve and the severity of ventricular wall hypertrophy) were absent in the association of AS + MS. The absence of myocardial hypertrophy can not be fully explained. It could be related to a decreased filling on the left ventricle and therefore a smaller systolic ejection volume because of the mitral obstruction.