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PubMed2006

19F fast magic-angle spinning NMR studies of perfluoroalkanoic acid self-assembled monolayers.

The bonding and dynamic properties of perfluoroalkanoic acid self-assembled monolayers (SAMs) on zirconia and titania powders were characterized by Fourier transform infrared and solid-state 19F magic-angle spinning NMR spectroscopy. The perfluoro fatty acids investigated included C(n)F(2n+1)CO2H, n = 7, 13, 15 and 17. The acids bind to both metal oxides via ionic carboxylate bonds, but complete monolayers are only formed on the zirconia. The shift of the CF3 group from -83 ppm in the bulk state to -85 ppm for the adsorbed monolayers is assigned to CF3 groups located at the air/monolayer interface. With the exception of the perfluorooctanoic acid, 19F spin lattice relaxation measurements indicate that the fluorocarbon chains of the adsorbed acids, even in the case of densely packed monolayers, are significantly more mobile than those in the bulk state. The motions associated with the enhanced mobility of the adsorbed acids are proposed to involve reorientations along the long chain axes. No evidence for chain melting in the fluorocarbon SAMs is found for temperatures well above the melting temperature of the bulk acids.

Journal Article↗
PubMed2006

The application of 1H high-resolution magic-angle spinning NMR for the study of clay-organic associations in natural and synthetic complexes.

The preferential sorption of model compounds to calcium-exchanged montmorillonite surfaces was investigated using 1H high-resolution magic-angle spinning (HR-MAS) and liquid-state NMR. Synthetic mixtures, representing the major structural categories abundant in natural organic matter (NOM), and two soil extracts were sorbed to montmorillonite. The NMR spectra indicate that, of the organic components observable by 1H HR-MAS NMR, aliphatic components preferentially sorb to the clay surface, while carbohydrates and amino acids mainly remain in the supernatant. These results may help explain the highly aliphatic nature of organic matter associated with clay fractions in natural soils and sediments. Investigations using the synthetic mixtures demonstrate a specific interaction between the clay surface and the polar region in 1-palmitoyl-3-stearoyl-rac-glycerol. Similar observations were obtained with natural soil extracts. The results presented have important implications for understanding the role of organoclay complexes in natural processes, and provides preliminary evidence that HR-MAS NMR is a powerful analytical technique for the investigation of organoclay complex structure and conformation.

Aluminum Silicates↗
PubMed2003

Concise large-scale synthesis of psilocin and psilocybin, principal hallucinogenic constituents of "magic mushroom".

The concise large-scale syntheses of psilocin (1) and psilocybin (2), the principal hallucinogenic constituents of "magic mushroom", were achieved without chromatographic purification. The key step in the synthesis of 2 was the isolation of the dibenzyl-protected intermediate (7) as a zwitterionic derivative (8), which was completely identified by means of 2D NMR analyses.

Agaricales↗
PubMed2005

Magic ring catenation by olefin metathesis.

[reaction: see text]. Olefin metathesis has been employed in the efficient syntheses of a [2]catenane with the templation being provided by the recognition between a secondary ammonium ion and a crown ether. In one approach, a crown ether precursor has been clipped around an NH2+ center situated in a macrocyclic ring, yielding the mechanically interlocked compound. In the other approach, the reversible nature of olefin metathesis allows for a magic ring synthesis to occur wherein two free macrocycles can be employed as the stationary materials, leading to the formation of the same [2]catenane.

Journal Article↗
PubMedDate not supplied

Biochemical characterization of rat intestine development using high-resolution magic-angle-spinning 1H NMR spectroscopy and multivariate data analysis.

We report details of metabolic profiles for small intestinal samples obtained using high-resolution magic-angle-spinning (HRMAS) (1)H NMR spectroscopy. Intact samples of jejunum and ileum from male Long Evans rats were analyzed on a 600 MHz spectrometer using standard one and two-dimensional (1)H NMR spectroscopic pulse sequences. The metabolic profiles of ileum and jejunum predominantly comprised a number of amino acids, lipids, glycerophosphocholine (GPC), choline, creatine, and ethanol, a number of carboxylic acids including acetate and lactate, and nucleoside bases including cytosine, isocytosine, and uracil. Principal component analysis (PCA) was applied to these NMR data to characterize the biochemical differences between jejunum and ileum tissues. Compared with ileum, jejunum contained higher levels of lipids, GPC, choline, lactate and creatinine, but lower levels of amino acids and acetate. In addition, the age dependence of the biochemical composition of intestinal tissues from young rats (15, 36 days and 3-4 months old) was studied. In general, levels of lipids, lactate, taurine and creatinine were positively correlated with age while amino acids and GPC decreased in the older age group. This study will provide a metabolic reference for further studies assessing the metabolic consequences of nutrition, stress and gut microbiota on intestinal composition.

Age Factors↗
PubMed2001

Secondary chemical shifts in immobilized peptides and proteins: a qualitative basis for structure refinement under magic angle spinning.

Resonance assignments recently obtained on immobilized polypeptides and a membrane protein aggregate under Magic Angle Spinning are compared to random coil values in the liquid state. The resulting chemical shift differences (secondary chemical shifts) are evaluated in light of the backbone torsion angle psi previously reported using X-ray crystallography. In all cases, a remarkable correlation is found suggesting that the concept of secondary chemical shifts, well established in the liquid state, can be of similar importance in the context of multiple-labelled polypeptides studied under MAS conditions.

Carbon↗
PubMed1988

Monoclonal antibodies as magic bullets.

Monoclonal antibodies have been used as experimental therapy in humans since the beginning of the 1980s (A.N. Houghton and D. A. Scheinberg. Semin. Oncol. 13:165-179, 1986). They have been hailed as the prototypical magic bullet drug because of their inherent capacity for specificity. Consequently, monoclonal antibodies have many possible therapeutic applications with varied potential for successful outcome. Current review articles discussing monoclonal antibody therapy deal with the application of monoclonal antibodies within specific areas of medicine. The aim of this review is to summarize the current reviews and provide a broader perspective on the medical applications of monoclonal antibodies along with some general principles by which their therapeutic success or failure might be understood.

Animals↗
PubMed1993

The 3'-keto-diol equilibrium of trospectomycin sulfate bulk drug and freeze-dried formulation: solid-state carbon-13 cross-polarization magic angle spinning (CP/MAS) and high-resolution carbon-13 nuclear magnetic resonance (NMR) spectroscopy studies.

Understanding how moisture interacts with a drug or formulation is a critical component of product development. This study demonstrates how water affects the 3'-gem-diol<==>3'-keto equilibrium in trospectomycin sulfate bulk drug and freeze-dried formulation, as probed by solid-state carbon-13 cross-polarization magic angle spinning (CP/MAS) and high-resolution nuclear magnetic resonance (NMR) spectroscopy. Drying the bulk drug or formulation to low water levels dehydrates trospectomycin sulfate from the diol to the keto form. Carbon-13 CP/MAS NMR spectroscopy measures the keto drug concentration in solid samples directly. The bulk drug, which contains approximately 16% water, is more than 90% in the 3'-diol form. Oven drying to < 3% water converts approximately 75% of the drug to the 3'-keto form. The drug is formulated as a freeze-dried, sterile powder that can contain up to 12% water depending on the freeze-drying conditions. These studies show that the 3'-keto concentration rises uniformly (up to 75%) with decreasing residual water in the freeze-dried cake. The keto-diol equilibrium was also studied in solution by high-resolution carbon-13 NMR experiments, and it was found that raising the temperature or using dimethyl sulfoxide (DMSO) as a solvent also dehydrates the drug. For example, in aqueous solution at 25 degrees C, nearly all (> 95%) of the drug is in the 3'-diol form. After equilibration at 60 degrees C, however, the 3'-keto content increases to 7%, and in d6-DMSO solvent at 25 degrees C the drug is mostly (60%) in the 3'-keto form.

Carbon Isotopes↗
PubMed2004

Signal assignments and chemical-shift structural analysis of uniformly 13C, 15N-labeled peptide, mastoparan-X, by multidimensional solid-state NMR under magic-angle spinning.

Carbon-13 and nitrogen-15 signals of fully isotope-labeled 15-residue peptide, glycinated mastoparan-X, in a solid state were assigned by two- and three-dimensional NMR experiments under magic-angle spinning conditions. Intra-residue spin connectivities were obtained with multidimensional correlation experiments for C'-C(alpha)-C(beta) and N-C(alpha)-C(beta). Sequence specific assignments were performed with inter-residue C(alpha)-C(alpha) and N-C(alpha)C(beta) correlation experiments. Pulse sequences for these experiments have mixing periods under recoupled zero- and double-quantum (13)C-(13)C and (15)N-(13)C dipolar interactions. These correlation spectra allowed the complete assignments of (13)C and (15)N backbone and (13)C(beta) signals. Chemical shift analysis of the (13)C and (15)N signals based on empirical and quantum chemical databases for proteins indicated that the backbone between residues 3 and 14 forms alpha-helix and residue 2 has extended conformation in the solid state. This structure was compared with the G-protein- and membrane-bound structures of mastoparan-X.

Carbon Isotopes↗
PubMed1997

Magical ideation and social anhedonia as predictors of psychosis proneness: a partial replication.

The authors compared college students identified by high scores on the Magical Ideation Scale (M. Eckblad & L. J. Chapman, 1983) and the Revised Social Anhedonia Scale (MagSoc; n = 28; M. Eckblad, L. J. Chapman, J. P. Chapman, & M. Mishlove, 1982) with control participants (n = 20) at a 10-year follow-up assessment in an attempt to replicate L. J. Chapman, J. P. Chapman, T. R. Kwapil, M. Eckblad, and M. C. Zinser's (1994) report of heightened psychosis proneness in MagSoc individuals. The MagSoc group exceeded the control group on severity of psychotic-like experiences; ratings of schizotypal, paranoid, and borderline personality disorder symptoms; and rates of mood and substance use disorders. Two of the MagSoc participants but none of the control participants developed psychosis during the follow-up period (a nonsignificant difference). Consistent with L. J. Chapman et al.'s findings, the groups did not differ on rates of personality disorders or relatives with psychosis.

Adult↗
PubMed1993

Earvin "Magic" Johnson's HIV serostatus disclosure: effects on men's perceptions of AIDS.

The effects of celebrity self-disclosure of human immunodeficiency virus (HIV) seropositivity on perceptions of HIV and Acquired Immunodeficiency Syndrome (AIDS) were investigated. AIDS-related interest and knowledge measures were collected from 468 men before and after basketball star Earvin "Magic" Johnson's self-disclosure of HIV seropositivity. Increased interest in AIDS paralleled media coverage of the announcement, with the most substantial effects occurring within 2 weeks. Perceived impact of the disclosure was greatest among African-American men and men who had not previously known someone with HIV-AIDS. Celebrity self-disclosure appears to affect perceptions through mechanisms similar to those involved in personally knowing someone infected with HIV.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Structure of a protein determined by solid-state magic-angle-spinning NMR spectroscopy.

The determination of a representative set of protein structures is a chief aim in structural genomics. Solid-state NMR may have a crucial role in structural investigations of those proteins that do not easily form crystals or are not accessible to solution NMR, such as amyloid systems or membrane proteins. Here we present a protein structure determined by solid-state magic-angle-spinning (MAS) NMR. Almost complete (13)C and (15)N resonance assignments for a micro-crystalline preparation of the alpha-spectrin Src-homology 3 (SH3) domain formed the basis for the extraction of a set of distance restraints. These restraints were derived from proton-driven spin diffusion (PDSD) spectra of biosynthetically site-directed, labelled samples obtained from bacteria grown using [1,3-(13)C]glycerol or [2-(13)C]glycerol as carbon sources. This allowed the observation of long-range distance correlations up to approximately 7 A. The calculated global fold of the alpha-spectrin SH3 domain is based on 286 inter-residue (13)C-(13)C and six (15)N-(15)N restraints, all self-consistently obtained by solid-state MAS NMR. This MAS NMR procedure should be widely applicable to small membrane proteins that can be expressed in bacteria.

Animals↗
PubMed2003

Antiplatelet therapy: in search of the 'magic bullet'.

The central importance of platelets in the development of arterial thrombosis and cardiovascular disease is well established. No other single cell type is responsible for as much morbidity and mortality as the platelet and, as a consequence, it represents a major target for therapeutic intervention. The growing awareness of the importance of platelets is reflected in the increasing number of patients receiving antiplatelet therapy, a trend that is likely to continue in the future. There are, however, significant drawbacks with existing therapies, including issues related to limited efficacy and safety. The discovery of a 'magic bullet' that selectively targets pathological thrombus formation without undermining haemostasis remains elusive, although recent progress in unravelling the molecular events regulating thrombosis has provided promising new avenues to solve this long-standing problem.

Animals↗
PubMed2001

Investigation of water environments in a C18 bonded silica phase using 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy.

High resolution 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra have been obtained on typical C18 bonded silicas used in chromatographic solid-phase extraction separations. It has been shown for the first time that water molecules distributed in distinct physico-chemical environments within the chromatographic system can be detected directly using a simple 1H MAS NMR measurement. The resonances assigned to water protons in differing physico-chemical environments have distinct chemical shifts, line widths, relaxation times (T1 and T2) and also exhibit temperature dependent coalescence behaviour. This novel MAS approach may lead to a better understanding of the environments of other analytes in mixtures during such separations.

Journal Article↗
PubMed1992

[Allergic rhinopathy: Magic Lite SQ Allergy Screen Inhalant and CAP-FEIA SX1--comparison of two allergen-specific screening tests in serum].

Although total IgE determination in the diagnosis of allergic rhinitis has been proposed for screening, specific tests seem to be more efficient. In this study, Magic Lite SQ Allergy Screen Inhalant (ML) and CAP-FEIA Phadiatop (CF) were compared in serum in a group of 101 patients with allergic rhinitis (41 women, 60 men, mean age 31.4 years, range 7-69) and 37 controls (17 women, 20 men, mean age 38.3 years, range 6-68). All patients were suffering from nasal disease. The diagnosis based on case history, skin prick test, total and specific IgE determination and nasal challenge tests. ML was found to have a sensitivity of 96% and a specificity of 83.8% while CF achieved a sensitivity of 94.1% and a specificity of 94.6%. Efficiency was 92.8% for ML and 94.2% for CF. A positive predictive value of 94.2% for ML and of 97.9% for CF was calculated while the negative predictive value was 88.6% for ML and 85.4% for CF. It is concluded, that both ML and CF are suitable allergy screening tests able to give a 100% diagnostic security in combination with further examinations, especially regarding the case history.

Adolescent↗
PubMed2005

Novel structures and energy spectra of hydroxylated (SiO2)8-based clusters: searching for the magic (SiO2)8O2H3- cluster.

The prominent (SiO(2))(8)O(2)H(3) (-) mass peak resulting from the laser ablation of hydroxylated silica, attributed to magic cluster formation, is investigated employing global optimization with a dedicated interatomic potential and density functional calculations. The low-energy spectra of cluster isomers are calculated for the closed shell clusters: (SiO(2))(8)OH(-) and (SiO(2))(8)O(2)H(3) (-) giving the likely global minima in each case. Based upon our calculated cluster structures and energetics, and further on the known experimental details, it is proposed that the abundant formation of (SiO(2))(8)O(2)H(3) (-) clusters is largely dependent on the high stability of the (SiO(2))(8)OH(-) ground state cluster. Both the (SiO(2))(8)O(2)H(3) (-) and (SiO(2))(8)OH(-) ground state clusters are found to exhibit cagelike structures with the latter containing a particularly unusual tetrahedrally four-coordinated oxygen center not observed before in either bulk silica or silica clusters. The bare ground state (SiO(2))(8)O(2-) cluster ion core is also found to have four tetrahedrally symmetric Si==O terminations making it a possible candidate, when combined with suitable cations, for extended cluster-based structures/materials.

Journal Article↗
PubMed2005

Through-space contributions to two-dimensional double-quantum J correlation NMR spectra of magic-angle-spinning solids.

A routinely used assumption when interpreting two-dimensional NMR spectra obtained with a commonly used double-quantum (DQ) magic-angle-spining (MAS) pulse sequence referred to as the refocused incredible natural abundance double-quantum transfer experiment (INADEQUATE) [A. Lesage, M. Bardet, and L. Emsley, J. Am. Chem. Soc. 121, 10987 (1999)] has been that correlation peaks are only observed for pairs of nuclei with a through-bond connectivity. The validity of this assumption is addressed here by theory, experiment, and computer simulations. If the isotropic chemical shifts of the two nuclei are different and the MAS frequency is far from rotational resonance, the theoretical description demonstrates that DQ correlation peaks are indeed indicative of a J coupling. However, if the isotropic chemical shifts are the same, it is shown that DQ peaks can appear for pairs of nuclei even in the absence of a through-bond J coupling. These peaks appear in the specific case of a pair of nuclei with a nonzero through-space dipole-dipole coupling and chemical shift anisotropy tensors having different principal magnitudes or orientations, provided that the MAS frequency is comparable to or smaller than the chemical shift anisotropies. Experimental 31P spectra recorded on a sample of TiP2O7 and computer simulations show that the magnitude of these anomalous peaks increases with increasing B0 magnetic field and that they decrease with increasing MAS frequency. This behavior is explained theoretically.

Journal Article↗