Solvation parameters. Part 5: physicochemical interpretation of experimental solvent values for stationary phases of gas-liquid chromatography.

It has been demonstrated for a long time that in the particular case of gas-liquid chromatography (GLC), a linear free energy relationship (LFER) of five terms can be established, each term including a parameter of solute and a parameter of solvent. The nature of some of these parameters has been quite clearly identified, even if not always well predicted from the molecular structure. First of all, the five solute parameters: two involved in the hydrogen bonding and three in the Van der Waals forces; secondly, the two solvent parameters involved in hydrogen bonding. It was remaining an uncertainty concerning the nature of the solvent parameters named D, W and E, respectively associated with the solute parameters of dispersion, orientation and induction/polarizability. This uncertainty has been solved using experimental chromatographic data of McReynolds (56 phases) and of the Kováts group (11 phases). The parameter W appears as of polar nature strictly speaking. The parameters D and E can be expressed by two opposite bilinear functions of 1/V (inverse of molecular volume) and PSA/V (ratio of the polar surface area over the molecular volume). These results are in agreement with previous studies limited to alkanes by the Kováts group.

Application of the U and gamma' models in binary sweet taste mixtures.

The U and Gamma' models of sensory interactions, successfully applied in olfaction for several years, are tested here using data from published studies on sweetness. The models are subsequently tested on new data obtained in studies of binary mixtures of four sodium sulfamates. The U model allows for the estimation of a global interaction, whereas the Gamma' model allows for the distinction between that which is due to an intrinsic interaction in the mixture itself and that which may be due to the power function exponents in the mixture. The models give satisfactory predictions for observed phenomena of sweet taste suppression, synergism or pure additivity. Additionally, they appear to be more suitable than other models recently applied in taste, particularly the equiratio model. Application of the models to the sulfamate mixtures, reveals additivity for sodium cyclohexylsulfamate (cyclamate)/potassium cyclohexylsulfamate and sodium cyclohexylsulfamate/sodium exo-2-norbornylsulfamate, respectively; whereas for sodium cyclohexylsulfamate/sodium 3-bromophenylsulfamate, the models revealed a slight hypo addition which is simply due to the dissimilarity values of the power function exponents of the components.

[Aortic atheroma: not a sensitive indicators for coronary artery disease in patients with mitral valve disease]. / L'athérome aortique: indicateur peu sensible de coronaropathie dans les valvulopathies mitrales.

Aortic atheroma detected by transoesophageal echocardiography has been reported to be a good prognostic marker for coronary disease on angiography. The value of this detection in valvular heart disease would be to avoid preoperative coronary angiography in asymptomatic patients. The aim of this study was to assess the prognostic value of aortic atheroma in a population with a low prevalence of coronary artery disease in whom transoesophageal echocardiography was systematically performed. In addition, calcification of the aortic knuckle, a marker of atherosclerosis, was analysed by simple chest X-ray. One hundred and ninety two patients (103 men, 89 women; mean age: 63.1 +/- 15 years), operated for mitral valve replacement, underwent transoesophageal echocardiography, angiography, within 6 months, and chest X-ray. The cardiovascular risk factors, presence of aortic atherome, angiographic coronary artery disease and aortic calcification were studied. Aortic atheroma was observed in 72 patients (37.5%), usually in the descending thoracic aorta (73.6%). Coronary stenosis was observed in 36 patients (18.7%). On univariate analysis, aortic atherome predicted coronary stenosis with a sensitivity of 53%, specificity of 66% and positive predictive value of 26% and negative predictive value of 86%, compared with chest X-ray: 71%, 65%, 33% and 90%, respectively. In multivariate analysis, only hypercholesterolaemia, smoking and age predicted the presence of coronary artery disease. The presence of aortic atheroma was not predictive (p = 0.3). The authors conclude that aortic atheroma does not predict the presence of coronary artery disease in a patient population with mitral valve disease and a low prevalence of coronary artery disease. Simple chest X-ray has almost the same diagnostic value. The association of these two investigations does not give sufficient negative predictive values to avoid coronary angiography.

Echocardiographic demonstration of rupture of intraseptal hydatid cyst.

We report a case of an intracardiac hydatid cyst observed before and after rupture complicated by a pulmonary embolus. The echocardiographic findings are analyzed and discussed. This dramatic course underscores the surgical emergency of cardiac hydatidosis.

[Primitive leiomyosarcoma of the right atrium presenting with a pulmonary embolism]. / Léiomyosarcome primitif de l'oreillette droite révélé par une embolie pulmonaire.

Primary Cardiac leiomyosarcoma is a very rare condition. The authors report the case of a 64 year old woman admitted to hospital for suspected pulmonary embolism, confirmed by thoracic angio-CT scan. Despite thrombolytic therapy, a persistent poor haemodynamic condition associated with a superior vena cava syndrome led to a transoesophageal echocardiographic examination which demonstrated an abnormal intra-right atrial mass obstructing the tricuspid valve. At surgery, a leio-myosarcoma was successfully resected under good conditions. During systematic three-monthly clinical and echocardiographic follow-up, transoesophageal echocardiography detected an asymptomatic local recurrence at 15 months, for which surgery was repeated with adjuvant chemotherapy.

[Hematoma of the aortic wall: from diagnosis to treatment]. / Hématome de la paroi aortique: du diagnostic au traitement.

Haematoma of the thoracic aortic wall is a relatively new concept, the physiopathology of which remains controversial. It results from an haemorrhage of the aortic wall due to rupture of the vasa-vasorum without communication with the arterial lumen. This is a diagnosis of elimination of dissection of the aorta which has been made possible by modern techniques of imaging, such as transoesophageal echocardiography, helicoidal scanner and magnetic nuclear resonance imaging. The prognosis of haematoma of the aortic wall is not as bad as that of dissection of the aorta. Recent studies have shown that the condition may stabilise, regress or progress towards complications of two types: early, dissection or fissuration of the aorta, and late, aortic aneurysm. This is a medico-surgical emergency, the treatment of which is not well codified. However, schematically, haematoma of the aortic wall should be managed in the same way as dissection of the aorta: surgery when the ascending aorta is affected, medical treatment in other cases in the absence of complications.

Early and long-term (one-year) effects of the association of aspirin and oral anticoagulant on thrombi and morbidity after replacement of the mitral valve with the St. Jude medical prosthesis: a clinical and transesophageal echocardiographic study.

OBJECTIVES: The aim of the study was to test the value of low dose aspirin associated with standard oral anticoagulants (OAC) after mechanical mitral valve replacement (MMRV) to reduce strands, thrombi and thromboembolic events. BACKGROUND: Strands and thrombi are thought to increase the risk of embolic events after MMVR, particularly in the immediate postoperative period. METHODS: Two hundred twenty-nine patients were prospectively recruited: 109 patients (group A+) were randomly assigned to aspirin (200 mg per day) with OAC and 120 patients (group A-) to OAC alone (international normalized ratio 2.5 to 3.5). All patients were subjected to multiplane transesophageal echocardiography at nine days and five months and were followed up for one year. RESULTS: At nine days and five months, there was a high and comparable incidence of strands in the two groups (group A+: 44%, 58%; group A-: 49%, 63%). However, the incidence of nonobstructive periprosthetic valve thrombi was significantly lower in group A+ at 9 days: 5% versus 13%, p = 0.03. Total thromboembolic events were reduced in group A+ (9% vs. 25%, p = 0.004) although there was an increased incidence of gastrointestinal hemorrhage (7% vs. 0%). Overall mortality was 9% in group A+ and 4% in group A-. Valve-related events were similar in both groups. Early thrombi, but not strands, were associated with higher morbidity, especially thromboembolic events (30% vs. 13%, p = 0.003). CONCLUSIONS: One year after MMVR, the association of aspirin with OAC reduced thrombi and thromboembolic events, but not morbidity, due to an increase in hemorrhagic complications.

[Treatment of left atrial thrombosis by low-molecular-weight heparin. A preliminary study of 6 cases]. / Traitement des thrombus auriculaires gauches par héparine de bas poids moléculaire à doses curatives. Etude préliminaire à propos de 6 cas.

Left atrial thrombosis is a serious complication of atrial fibrillation because of its embolic potential, especially for the cerebral circulation. These thrombi are usually treated by oral anticoagulation. The authors studied the efficacy and tolerance of a low molecular weight heparin. Enoxaparin, in the treatment of this condition. This was a prospective study carried out over a 1 year period. Patient recruitment came from the transoesophageal echocardiography laboratory: of 15 thrombi detected, 6 were treated by ambulatory Enoxaparin therapy. Five of the 6 patients had no signs of left atrial thrombosis after 3 weeks of Enoxaparin therapy. The left atrial thrombus of the 6th patient remained hyperechogenic and had decreased in length from 27 to 24 mm. No cases of bleeding, haematoma, embolism or thrombopenia were observed with this treatment. This preliminary study shows that low molecular weight heparin may be used as an alternative to classical oral anticoagulation for the treatment of left atrial thrombosis.

[Contrast echocardiography and myocardial perfusion: what is the current status?]. / Echocardiographie de contraste et perfusion myocardique: où en sommes-nous?

Progress in the field of echocardiographic contrast agent combined with progress in imaging techniques (second harmonic imaging, intermittent imaging, Doppler Energy) should allow a real revolution in the field of noninvasive cardiac imaging, and one of the main advantages will probably be myocardial perfusion imaging in ischaemic heart disease.

Olfactory quality: from descriptor profiles to similarities.

The model described here, which links olfactory semantic profiles to canonical similarities, performs significantly better than the current state of the art, mainly due to the use of an optimization procedure. Application of Tversky's model in this study shows that in olfaction, estimation of similarities is based exclusively on the distinctive elements of the profiles, and does not take into account the common elements. Moreover, the optimum number of descriptors to reckon with seems to lie between 25 and 30.

[Role of echocardiography in the diagnosis of acquired diseases of the thoracic aorta]. / Place de l'échocardiographie dans le diagnostic des maladies acquises de l'aorte thoracique.

The diagnosis and follow-up of acquired thoracic aortic disease have greatly improved with advances in transthoracic and transoesophageal echocardiographic techniques. In emergency situations, transoesophageal echocardiography is the key diagnostic investigation for dissection, significantly speeding up surgical referral. Atherosclerosis of the aorta is the second clinical situation in which transoesophageal echocardiography confirms its superiority over other imaging techniques for the recognition of intra-aortic debris carrying a high embolic risk.

[Value of echocardiography-dobutamine in the study of reserve myocardial contractility in aortic stenosis with alteration of left ventricular function. Apropos of a case]. / Intérêt de l'échocardiographie-dobutamine dans l'étude de la réserve de contractilité myocardique du rétrécissement aortique avec altération de la fonction ventriculaire gauche. A propos d'un cas.

The authors report a case of tight aortic stenosis, without coronary artery disease, presenting with heart failure, alteration of global left ventricular contractility and a low gradient. Increasing-dose dobutamine echocardiography demonstrated an improvement of myocardial contractility and an accentuation of the transvalvular gradient. The place of this examination in the therapeutic strategy and follow-up of the disease is discussed in the light of the current data of the literature.

[Graphical structuring of olfactory quality based on molecular parameters. Cases of experimental data from the André Holley group]. / Structuration graphique de la qualité odorante sur la base de paramètres moléculaires. Cas de données expérimentales du groupe de André Holley.

Olfactory quality, measured by Holley and coworkers in a series of six studies on frog olfactory mucosa, is compared with two molecular parameters for the set of 75 stimulants studied. On this basis, 96% of the odorants, grouped in 11 olfactory clusters, are correctly discriminated.

Solubility factors established by gas-liquid chromatography. A balance sheet.

Dravnieks and Laffort first used a method based on gas-liquid chromatography for establishing solubility factors (or parameters) of solutes. This method has been developed and improved over ten years (1972-1982) and applied to quantitative structure-activity relationships in olfaction. The physico-chemical and biological implications of this approach are reappraised.

[Sensitivity of bee antennae to binary mixtures of fragrant substances]. / Sensibilité antennaire de l'abeille à des mélanges binaires de substances odorantes.

An olfactory stimulator was built to study the sensitivity of insect antennae to binary mixtures. This apparatus can deliver nine kinds of calibrated odorous stimuli: the two pure components at three different concentrations, separate and mixed. The flux which reaches the preparation remains constant before, during and after each stimulation, in order to obtain a pure olfactory response, without any mechanical or thermal contamination. Theoretical models used in psychophysics are applicable to the recordings. Preliminary results on honey-bee workers are illustrated and discussed.