Injectivity and Stability for a Generic Class of Generalized Radon Transforms.

Let (M, g) be an analytic, compact, Riemannian manifold with boundary, of dimension n ≥ 2 . We study a class of generalized Radon transforms, integrating over a family of hypersurfaces embedded in M, satisfying the Bolker condition (in: Quinto, Proceedings of conference "Seventy-five Years of Radon Transforms", Hong Kong, 1994). Using analytic microlocal analysis, we prove a microlocal regularity theorem for generalized Radon transforms on analytic manifolds defined on an analytic family of hypersurfaces. We then show injectivity and stability for an open, dense subset of smooth generalized Radon transforms satisfying the Bolker condition, including the analytic ones.

The utility of the in vitro micronucleus test for evaluating the genotoxicity of natural and manmade nano-scale fibres.

A range of fibrous materials, including several types of asbestos and carbon fibres with nano scale diameters that had reported positive genotoxicity data (predominantly clastogenicity), were tested in the in vitro micronucleus test (OECD 487) in GLP-compliant studies in Chinese Hamster Ovary cells. Out of eight materials tested, only one (crocidolite, an asbestos fibre) gave a positive response either in the presence or absence of metabolic activation (S9) and at short (3h) or extended (24h) exposure times (p≤0.001). Our data suggest that the commonly used tests for clastogenicity in mammalian cells require extensive modification before fibrous materials are detected as positive, raising questions about the validity of these tests for detecting clastogenic and aneugenic fibrous materials.

Determination of gamma-aminobutyric acid in food matrices by isotope dilution hydrophilic interaction chromatography coupled to mass spectrometry.

The estimation of the dietary intake of gamma-aminobutyric acid (GABA) is dependent upon the knowledge of its concentration values in food matrices. To this end, an isotope dilution liquid chromatography-mass spectrometry method has been developed employing the hydrophilic interaction chromatography technique for analyte separation. This approach enabled accurate quantification of GABA in apple, potato, soybeans, and orange juice without the need of a pre- or post-column derivatization reaction. A selective and precise analytical measurement has been obtained with a triple quadrupole mass spectrometer operating in multiple reaction monitoring using the method of standard additions and GABA-d(6) as an internal standard. The concentrations of GABA found in the matrices tested are 7 microg/g of apple, 342 microg/g of potatoes, 211 microg/g of soybeans, and 344 microg/mL of orange juice.