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Area Method (area + method)
Selected AbstractsA Nomogram for Measurement of Mitral Valve Area by Proximal Isovelocity Surface Area MethodECHOCARDIOGRAPHY, Issue 8 2007Mehmet Uzun M.D. Introduction: Although its accuracy has been documented in many studies, the proximal isovelocity surface area (PISA) method is not used widely for mitral valve area (MVA) measurement. In this study, we prepared a new nomogram and tested its use in MVA assessment. Material and Methods: The study included 23 patients (age: 27 ± 5 years) with mitral stenosis, of whom 7 were in atrial fibrillation. The MVA was measured by four methods: planimetry (PL) (reference method), pressure-half time (PHT), conventional PISA (CP), and nomogram (Nomo) methods. The nomogram included two unknowns: (1) r; the radius of the first PISA section; (2) a; the length of the border opposite to the PISA angle in the triangle with both adjacent borders of 1 cm. The nomogram was also tested for its popularity potential by eight echocardiographers, none of whom were included in the author list. Results: Mean MVAPL was 1.85 ± 0.53 cm2 (range: 0.72,2.99), mean MVAPHT was 1.72 ± 0.56 cm2 (range: 0.91,3.30), mean MVACP was 1.69 ± 0.45 cm2 (range: 0.97,2.54), and MVANomo was 1.70 ± 0.44 cm2 (0.96,2.49). The nomogram correlated with planimetry (r = 0.87; P < 0.001), pressure half-time (r = 0.71; P < 0.001) and conventional PISA (r = 0.99; P = 0.000) methods. The nomogram method also correlated with planimetry in patients with atrial fibrillation (r = 0.81; P = 0.026). The echocardiographers found that the nomogram is superior to the planimetry and conventional PISA methods but inferior to the pressure half-time method in terms of simplicity. Conclusion: The new nomogram is potentially helpful in measurement of MVA. It may be used as an additional method in assessing severity of mitral stenosis. [source] Comparison of Proximal Isovelocity Surface Area Method and Pressure Half Time Method for Evaluation of Mitral Valve Area in Patients Undergoing Balloon Mitral ValvotomyECHOCARDIOGRAPHY, Issue 9 2005Thottuvelil Narayanan Sunil Roy M.D. Background: The pressure half time (PHT) method is unreliable for measurement of mitral valve area (MVA) immediately after valvotomy. The proximal isovelocity surface area (PISA) method has been used to derive mitral valve area in patients with mitral stenosis. The aim of our study was to compare PISA method and PHT method in patients undergoing percutaneous balloon mitral valvotomy (BMV). Methods: The PISA was recorded from the apex and MVA was calculated using continuity equation by the formula 2,r2 Vr/Vm, where 2,r2 is the hemispheric isovelocity area, Vr is the velocity at the radial distance "r" from the orifice, and Vm is the peak velocity. A plain angle correction factor (,)/180 was used to correct the inlet angle subtended by leaflet tunnel as a result of leaflet doming. Results: MVA calculated using PISA method (r = 0.5217, P < 0.0001, SE = 0.016) and PHT (r = 0.6652, P < 0.0001, SE = 0.017) correlated well with 2D method in patients with mitral stenosis before BMV. After BMV, MVA by PISA method correlated well with 2D planimetry (r = 0.5803, P < 0.0001, SE = 0.053) but PHT showed poor correlation (r = 0.1334, P = 0.199, SE = 0.036). The variability of measurement of MVA was most marked with PHT method in the post-BMV period. Conclusion: The PISA method correlates well with 2D planimetry in patients with mitral stenosis before and after BMV and is superior to the PHT method in the post-BMV period where the latter may be unreliable. [source] Study on the inhibitory mechanism and binding mode of the hydroxycoumarin compound NSC158393 to HIV-1 integrase by molecular modelingBIOPOLYMERS, Issue 9 2009Ming Liu Abstract Human immunodeficiency virus type 1 integrase (IN) is an essential enzyme in the life cycle of this virus and also an important target for the study of anti-HIV drugs. In this work, the binding modes of the wild type IN core domain and the two mutants, that is, W132G and C130S, with the 4-hydroxycoumarin compound NSC158393 were evaluated by using the "relaxed complex" molecular docking approach combined with molecular dynamics (MD) simulations. Based on the monomer MD simulations, both of the two substitutions affect not only the stability of the 128,136 peptides, but also the flexibility of the functional 140s loop. In principle, NSC158393 binds the 128,136 peptides of IN; however, the specific binding modes for the three systems are various. According to the binding mode of NSC158393 with WT, NSC158393 can effectively interfere with the stability of the IN dimer by causing a steric hindrance around the monomer interface. Additionally, through the comparative analysis of the MD trajectories of the wild type IN and the IN-NSC158393 complex, we found that NSC15893 may also exert its inhibitory function by diminishing the mobility of the function loop of IN. Three key binding residues, that is, W131, K136, and G134, were discovered by energy decomposition calculated with the Molecular Mechanics Generalized Born Surface Area method. Characterized by the largest binding affinity, W131 is likely to be indispensable for the ligand binding. All the above results are consistent with experiment data, providing us some helpful information for understanding the mechanism of the coumarin-based inhibitors. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 700,709, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] GEOGRAPHERS AND THE TENNESSEE VALLEY AUTHORITY,GEOGRAPHICAL REVIEW, Issue 1 2004RONALD REED BOYCE ABSTRACT. The Tennessee Valley Authority (TVA) was the largest, most comprehensive, and most controversial regional development and planning project in U.S. history. Geographers were involved from its inception and made impressive contributions. Aside from the unit area method of data gathering and mapping, little is known about their contributions, some of which were truly ahead of their time. Although their work and recommendations were often discarded and unheeded because of political turbulence, the geographers rarely complained or entered into the political arena. Their work in the TVA has generally gone unheralded and even unappreciated within the geography profession. The primary purpose of this article is to document their contributions. [source] Experimental and clinical study of the combined effect of arterial stiffness and heart rate on pulse pressure: Differences between central and peripheral arteriesCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2005Theodoros G Papaioannou SUMMARY 1.,Pulse pressure (PP) constitutes an independent predictor of cardiovascular events and mortality in various populations. Heart rate (HR) and arterial stiffness, in addition to their independent predictive value for cardiovascular complications, seem to interact with regard to the modification of PP. The aim of the present study was to investigate the association of PP with HR under different levels of arterial compliance (AC), revealing their synergistic effects. 2.,Seventy-one normotensive and untreated hypertensive subjects were examined. Arterial compliance was measured by the ,area' method, whereas central blood pressures and wave reflections were evaluated using the Sphygmocor® system (AtCor Medical, Sydney, NSW, Australia). A hydraulic Windkessel model was also used to evaluate the independent effect of HR and AC on PP. Peripheral PP was associated only with mean pressure and AC. In contrast, central PP was further related to HR (20 b.p.m. decrease in HR resulted in central PP augmentation by 5.6 mmHg) regardless of mean pressure, stroke volume, age and gender. However, this association was statistically significant only for subjects with lower AC (< 1.1 mL/mmHg) and not for those with more compliant arteries. These findings are also in accordance with the experimental data. 3.,Aortic PP is affected to a greater degree by HR changes compared with peripheral PP. This response was observed only at high levels of arterial stiffness. 4.,The present study provides the first evidence regarding the combined effect of AC and HR on aortic PP, which may lead to larger clinical or epidemiological studies aiming to optimization of drug treatment and to a possible reduction of cardiovascular risk. [source] | ||||||||||