Effect of the cation model on the equilibrium structure of poly-L-glutamate in aqueous sodium chloride solution.

We demonstrate that different sets of Lennard-Jones parameters proposed for the Na(+) ion, in conjunction with the empirical combining rules routinely used in simulation packages, can lead to essentially different equilibrium structures for a deprotonated poly-L-glutamic acid molecule (poly-L-glutamate) dissolved in a 0.3M aqueous NaCl solution. It is, however, difficult to discriminate a priori between these model potentials; when investigating the structure of the Na(+)-solvation shell in bulk NaCl solution, all parameter sets lead to radial distribution functions and solvation numbers in broad agreement with the available experimental data.

Water-Methanol Mixtures: Simulations of Mixing Properties over the Entire Range of Mole Fractions.

Numerous experimental and theoretical investigations have been devoted to the hydrogen bond in pure liquids and mixtures. Among the different theoretical approaches, molecular dynamics (MD) simulations are predominant in obtaining detailed information, on the molecular level, simultaneously on the structure and the dynamics. Water and methanol are the two most prominent hydrogen-bonded liquids, and they and their mixtures have consequently been the subject of many studies; we revisit here the problem of the mixtures.

Enantioselective recognition at mesoporous chiral metal surfaces.

Chirality is widespread in natural systems, and artificial reproduction of chiral recognition is a major scientific challenge, especially owing to various potential applications ranging from catalysis to sensing and separation science. In this context, molecular imprinting is a well-known approach for generating materials with enantioselective properties, and it has been successfully employed using polymers. However, it is particularly difficult to synthesize chiral metal matrices by this method.

Different structures give similar vibrational spectra: the case of OH- in aqueous solution.

We have calculated the anharmonic OH(-)(aq) vibrational spectrum in aqueous solution with a "classical Monte Carlo simulation + QM/MM + vibrational" sequential approach. A new interaction model was used in the Monte Carlo simulations: a modified version of the charged-ring hydroxide-water model from the literature. This spectrum is compared with experiment and with a spectrum based on CPMD-generated structures, and the hydration structures and H-bonding for the two models are compared.

The permeation of methane molecules through silicalite-1 surfaces.

The permeation of methane molecules through the silicalite-1 surfaces with and without silanol groups has been studied by nonequilibrium molecular dynamics computer simulations. A newly fitted intermolecular potential between the methane molecules and the silanol is used. A control volume provides a nearly stationary gas phase close to the membrane.

Structure and dynamics of water confined in single-wall nanotubes.

The structure and dynamics of water confined in model single-wall carbon- and boron-nitride nanotubes (called SWCNT and SWBNNT, respectively) of different diameters have been investigated by molecular dynamics (MD) simulations at room temperature. The simulations were performed on periodically extended nanotubes filled with an amount of water that was determined by soaking a section of the nanotube in a water box in an NpT simulation (1 atm, 298 K). All MD production simulations were performed in the canonical (NVT) ensemble at a temperature of 298 K.

Molecular dynamics studies of the interface between a model membrane and an aqueous solution.

Molecular Dynamics (MD) computer simulation studies are reported for a system consisting of two model membranes in contact with an aqueous solution. The influence of the membrane on the adjacent liquid is of main interest in the present study. It is therefore attempted to make the system sufficiently large to encompass the entire region between bulk liquid and the membranes.

Emergency balloon angioplasty and digital subtraction angiography in the management of an acute iatrogenic occlusive dissection of a saphenous vein graft.

A 63-year-old male with status post quadruple aortocoronary bypass surgery suddenly complained of chest pain and had ST-segment elevation in lead III during routine coronary angiography. Subsequent selective injections showed occlusion of the bypass graft to the right coronary artery, whereas by digital angiography done 15 min earlier it had been patient. Iatrogenic dissection of the graft was assumed, and balloon recanalization was immediately performed.

[Change in indications for coronary angiography in a decade].

To characterize the changes in indications for coronary angiography we compared indications and therapeutic conclusions of cardiac catheterization, including coronary angiography, in 100 consecutive patients in 1975 and 100 consecutive patients in 1985. The baseline characteristics of the patients in the two groups were similar, except for age (50 +/- 10 vs 56 +/- 9 years, p less than 0.0001) and prior angioplasty (0 vs 12, p less than 0.

[Congenital intercoronary arterial anastomosis. Apropos of a case and review of the literature].

The authors report a case of coronary arterial anastomosis between the right coronary and left circumflex arteries in the absence of other coronary pathology. This is an exceptionally rare congenital malformation which is situated either in the atrioventricular groove or at the apex in the interventricular groove. It constitutes a diagnostic pitfall because, in contrast to a collateral circulation, it is not an indirect sign of occlusive coronary artery.

[Cardiac failure caused by an overdose of dantrolene].

A case is reported of cardiac failure with repeated pulmonary oedema in a female patient suffering from renal failure and having been given incremental doses of dantrolene sodium. On withdrawal of the drug, all symptoms disappeared. This muscle relaxant was considered not to have any depressive myocardial side-effects.

[Volume and regional contraction of the left ventricle studied with venous injection in subtraction angiography].

Unlabelled: The end-diastolic and end-systolic volumes, the left ventricular ejection fraction, and segmental contraction of the left ventricle (5 areas) were determined at rest in 31 patients using two methods: conventional cineventriculography (as reference) and digital subtraction angiography by venous injection (the inferior vena cava).

Results: the volumes and ejection fraction obtained by digital subtraction angiography were reliable, though slightly less accurate than conventional ventriculography. Quantification of segmental contraction was satisfactory in the apical, anterolateral, and anteroinferior portions.

Acute hemodynamic effects of intravenous amiodarone in patients with coronary artery disease.

The acute hemodynamic effects of intravenous amiodarone (Cordarone injectable; Labaz) were studied during cardiac catheterization in 16 male patients with coronary artery disease (age range, 38-64 years; mean, 53 years). Amiodarone was administered as a bolus at a dosage of 5 mg/kg bodyweight over a 1-min period. Measurements were made 5, 10, and 15 min thereafter.

Non-selective intra-arterial digital subtraction angiography for the assessment of coronary artery bypass grafts.

Non-selective intra-arterial digital subtraction angiography (DSA) was performed immediately before selective coronary and bypass angiography in 33 consecutive symptomatic patients 48 +/- 30 months after coronary surgery, for the assessment of 75 coronary bypass grafts. Forty ml of non-ionic, low-iodine content contrast medium (iohexol) were injected into the ascending aorta at 10-20 ml/sec through a 7 or 8 F femoral pigtail catheter. Electrocardiogram-triggered images were acquired on a Siemens Digitron II apparatus in multiple projections in 24 patients and in a single projection in 9 patients.

[Global ventricular function and synchronism of contraction during and after exertion].

Phase analysis and ejection fraction (EF) of the left ventricle were obtained by radionuclide angiography in 53 patients at rest, during submaximal exercise and 3-8 minutes after exercise. The standard deviation of the peak of the histogram of phases (SDP) was used as an index of the synchronicity of regional contraction. The material comprised 13 sportsmen and 40 patients who underwent coronarography, 12 of whom had normal coronaries and 28 significant lesions.

[Angiographic study of the dynamics of the interventricular septum].

The interventricular septum was studied by biventricular angiography in 52 patients divided into 4 groups: the first group consisted of 14 normal subjects; the second of 10 patients with hypertension (9 cases) or aortic stenosis (1 case); the third, of 19 patients with echocardiographic asymmetric septal hypertrophy, and the fourth, of 9 cases of cardiomyopathy with dilatation. The following parameters were measured: septal thickness at 4 different points and mean septal thickness, the height (long axis) and surface of the septum in diastole and systole. The percentage variation was calculated.

[Surgical correction of interventricular communication with pulmonary stenosis in a hemophiliac].

Open heart surgery was performed in a 5 year-old boy with severe hemophilia A and large ventricular septal defect with pulmonary stenosis. High doses of Factor VIIIC superconcentrates delivered as small transfusion volumes allowed the use of extracorporeal circulation with heparin. Transfusions began 5 hours before surgery and were stopped 21 days later.

[Value of computer tomography compared to angiography and echocardiography in the diagnosis of intracardiac thromboses].

Until recently the only means of diagnosing intracardiac thromboses were angiography and M mode and 2D echocardiography. The aim of this study was to assess the value of CAT scanning in this field and to compare it with angiography and ultrasonography. Twenty intracardiac thromboses were studied in 19 patients by CAT scanning: 14 in the left ventricle, 2 in the right ventricle, and 4 in the left atrium, one patient having both left and right ventricular intracavitary thrombosis.

Diastolic mitral gradient without associated valvular stenosis: usefulness of two-dimensional echocardiography for a correct diagnosis.

A diastolic gradient across the mitral valve is generally indicative of mitral valve stenosis. In the present study, echocardiography was used to demonstrate two less common causes of left ventricular inflow obstruction: one patient had a fibromuscular membrane beneath the valve, the other a large vegetation attached to the posterior leaflet of the mitral valve. Echocardiography proved to be the optimal imaging technique in each case.

Association of coarctation of the thoracic aorta with fibromuscular dysplasia of the renal arteries: a case report.

The case of a 25-year-old woman with coarctation of the thoracic aorta and combined bilateral fibromuscular dysplasia of the renal arteries is reported. Although marked hemodynamic changes induced by the coarctation were probably pre-existent, hypertension was revealed only during the last month of her first pregnancy and was spontaneously corrected 2 months post partum. Surgical treatment of the thoracic coarctation did not influence blood pressure which remained normal.