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.

Solvation parameters. 2. A simplified molecular topology to generate easily optimized values.

This paper describes a generalized method to establish the values of the five solvation parameters of solutes, which reflect, together with the five solvation parameters of solvents, the intermolecular forces involved in solutions and in some biological phenomena. The tool applied for this purpose is a simplified molecular topology (SMT), which principally takes into account, for each atom of a molecule, its nature, the nature of its bonds, and in some cases the nature of its first neighbors. The learning material used to weight the molecular features generated by SMT are two sets of experimentally determined solvation parameters, established in a previous work (Laffort et al.

Solvation parameters Part 1. Mutual improvements of several approaches and determination of two first sets of optimized values.

An improvement in the characterization and the determination of the solvation parameters allows, not only a better knowledge of solutions, but also of some biological phenomena. In this paper, we test several published data and approaches in the field of solubility and solvation parameters in two ways: (i) the mutual independence of the parameters and (ii) their ability to take into account recently published gas-liquid chromatographic data. From this enquiry it arises that the most suitable published values are those of Abraham concerning 314 solutes.

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.

[Aortic atheroma: not a sensitive indicators for coronary artery disease in patients with mitral valve disease].

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.

[Treatment of left atrial thrombosis by low-molecular-weight heparin. A preliminary study of 6 cases].

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.

Management of Nonobstructive Thrombosis of Prosthetic Mitral Valve in Asymptomatic Patients in the Early Postoperative Period: A Study in 20 Patients.

The purpose of the present study was to determine the optimal management of nonobstructive thrombi in the early postoperative period after mitral valve replacement.Twenty cases of early thrombi were revealed by systematic transesophageal echocardiography (TEE) performed 9 days after surgical implantation of 229 St. Jude prostheses.

Assessment of Left Ventricular Area at Risk by Myocardial Contrast Two-Dimensional Echocardiography: An Evaluation of a New Animal Model.

BACKGROUND: New echocardiographic contrast agents are commonly tested in the dog model. However, this species has a number of drawbacks, including difficulties in experimentation, cost, and ethical considerations. The rabbit has a number of advantages due to its relative simple coronary circulation.

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].

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.

[Hematoma of the aortic wall: from diagnosis to treatment].

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.

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.

[Contrast echocardiography and myocardial perfusion: what is the current status?].

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.

[Role of echocardiography in the diagnosis of acquired diseases of the thoracic aorta].

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.

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.

[Value of echocardiography-dobutamine in the study of reserve myocardial contractility in aortic stenosis with alteration of left ventricular function. Apropos of a case].

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].

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].

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.