The aggregation behavior of sodium taurocholate (TC) in deuterium oxide without salt was investigated by one-and two-dimensional NMR spectroscopy. Analysis of the concentration dependence of the chemical shift suggests that TC forms a dimer and a pentamer. The equilibrium constants of dimerization and pentamerization are close to those already determined by chromatography in the presence of 154 mM sodium chloride. The structure of the dimer is estimated from the NOESY and ROESY spectra of a 8 mM TC solution and molecular mechanics calculations. The inter-proton distances calculated from the molecular mechanics structure are consistent with the NOE and ROE intensities, whereas those calculated from the X-ray crystal structure (hydrogen-bonded structure) are inconsistent. The molecular mechanics structure is stabilized by hydrophobic interactions between the steroid nuclei and by reduced electrostatic repulsion between the sulfonate ions. The local structures of the pentamer are estimated on the basis of the ROESY spectrum of a 30 mM TC solution. The pentamer of TC is formed mainly by hydrophobic interactions. Thus, a novel NMR method in surfactant chemistry has provided the first step to resolve the 20-year debate about the structures of dimers and micelles of TC. This novel approach in surfactant chemistry will serve to estimate the structures of micelles of other natural and synthetic surfactants.
Proton NMR spectroscopy was applied to determine the binding constants and the solution structures of 1:1 R-cyclodextrin (R-CD) complexes with hexyltrimethylammonium (HTAB) and octyltrimethylammonium (OTAB) bromides. Chemical shift data of all protons, referred to an internal standard, were used to determine reliable binding constants and chemical shift variations ∆δ complex induced by complex formation. The ROESY spectra of aqueous solutions containing R-CD and HTAB or OTAB provide information about rough structures of the complexes. The alkyl chains of HTAB and OTAB are incorporated from the wide rim of the R-CD cavity. The ROE intensities of intermolecular cross-peaks are plotted against the effective interproton distances for many structures different in the penetration depth of the alkyl chain. Detailed structures of the R-CD complexes with HTAB and OTAB are determined from the best correlations between the ROE intensities and the interproton distances. The ∆δ complex values for the protons of propanol, HTAB, and OTAB depend on the position located in the R-CD cavity. For instance, the proton near the proton H3 of R-CD exhibits the largest variation (ca. 0.2 ppm). The present data on single-and short-chain surfactants will provide the basis for determining the stoichiometry, the binding constants, and the structures of CD complexes with longchain surfactants and double-chain surfactants.
ELPS is a hybrid of head and neck surgery and gastrointestinal endoscopic treatment, and enjoys the merit of both procedures. ELPS makes it possible to perform minimally-invasive surgery, preserving both the swallowing and phonation functions.
A good prognosis can be expected for most, but not all, cases of thyroid papillary cancer. Numerous molecular studies have demonstrated beneficial treatment and prognostic factors in various molecular markers. Whereas most previous reports have focused on genomics and proteomics, few have focused on lipidomics. With the advent of mass spectrometry (MS), it has become possible to identify many types of molecules, and this analytical tool has become critical in the field of omics. Recently, imaging mass spectrometry (IMS) was developed. After a simple pretreatment process, IMS can be used to examine tissue sections on glass slides with location information.Here, we conducted an IMS analysis of seven cases of thyroid papillary cancer by comparison of cancerous with normal tissues, focusing on the distribution of phospholipids. We identified that phosphatidylcholine (16:0/18:1) and (16:0/18:2) and sphingomyelin (d18:0/16:1) are significantly higher in thyroid papillary cancer than in normal thyroid tissue as determined by tandem mass (MS/MS) analysis. These distributional differences may be associated with the biological behavior of thyroid papillary cancer.
This paper discusses an approach to human action recognition via local feature tracking and robust estimation of background motion. The main contribution is a robust feature extraction algorithm based on KLT tracker and SIFT as well as a method for estimating dominant planes in the scene. Multiple interest point detectors are used to provide large number of features for every frame. The motion vectors for the features are estimated using optical flow and SIFT based matching. The features are combined with image segmentation to estimate dominant homographies, and then separated into static and moving ones regardless the camera motion. The action recognition approach can handle camera motion, zoom, human appearance variations, background clutter and occlusion. The motion compensation shows very good accuracy on a number of test sequences. The recognition system is extensively compared to state-of-the art action recognition methods and the results are improved.
A method for calculations of molecular surface area changes with the docking of host and guest is developed and applied to the estimation of the structures and binding constants of cyclodextrin inclusion systems. Each molecule of the host and guest is regarded to consist of hydrophilic and hydrophobic groups. The change ΔS in water-accessible surface area with the docking of these host and guest molecules is divided into four terms: ΔSoo(HG), ΔSow(HG), ΔSwo(HG), and ΔSww(HG). For instance, ΔSoo(HG) stands for the change in host hydrophobic surface area by overlapping with guest hydrophobic surface area. When a guest molecule is moved along the symmetry axis of cyclodextrin, the structure of the complex having the maximum ΔSoo(HG) value is close to its crystal structure. Thus, we can estimate the “solution” structure of the complex from the maximum ΔSoo(HG) value. Using this method, we predict the solution structures of six cyclodextrin inclusion systems. Furthermore, we find that the logarithm of the 1:1 binding constant is linear with the maximum ΔSoo(HG) value for 11 systems including α-, β-, and γ-cyclodextrins and aliphatic and aromatic guest molecules. The present results would be applied to other cyclodextrin inclusion systems and protein−ligand systems.
The complex formation of 1 mmol kg -1 diheptanoylphosphatidylcholine (DHPC) with Rand γ-cyclodextrins (CD) in deuterium oxide solutions has been investigated by proton nuclear magnetic resonance. With the addition of CD, the variations in proton chemical shifts of DHPC and in vicinal coupling constants of the glycerol C1H 2 -C2H protons allow us to estimate the equilibrium constant and stoichiometry of complexation and to image the three-dimensional structures of their complexes. The addition of R-CD causes an increase of the trans conformer (T) of DHPC and a decrease of the gauche + conformer (G + ), whereas the addition of γ-CD results in the reverse changes. From the dependence of the chemical shift of a DHPC proton on the CD concentration, we estimate the equilibrium formation macroconstants K 1 and K 2 of 1:1 and 1:2 complexations of DHPC and CD. In contrast with the case for single-chain surfactants, the K 1 value for R-CD is smaller than that for γ-CD and the K 2 value for γ-CD is smaller than K 1 for γ-CD. The equilibrium microconstants of CD complexation of the three rotamers G + , G -(gauche -), and T of DHPC are also estimated from the concentration dependence of vicinal coupling constants. Predominant binary complexes of R-CD and γ-CD are composed of the Gform and the G + form, respectively. The T of the three conformers of DHPC tends most easily to form the ternary complex with R-CD and γ-CD. There seems to be almost no distinction between the 1-and 2-heptanoyl chains of DHPC for binding to the R-CD cavity. The inclusion of DHPC into the γ-CD cavity induces magnetic nonequivalence of the terminal methyl protons of chains 1 and 2. It is likely that DHPC is bound from the side of secondary hydroxyl groups of γ-CD. The threedimensional structures of major complexes are proposed on the basis of the magnitude of chemical-shift variation of each proton of DHPC and CD. The intermediate methylene groups of DHPC are located near the center of an R-CD cavity, whereas the two terminal methyl groups of DHPC are deeply penetrated into a γ-CD cavity. The above results are discussed in relation to the hemolysis of erythrocytes, one of the serious toxicities of CD caused when it was added in foods and pharmaceuticals.
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