Efficient mutation detection in MEN1 gene using a combination of single-strand conformation polymorphism (MDGA) and heteroduplex analysis

For facilitated genotypic analysis of multiple endocrine neoplasia type 1 (MEN1), a familial syndrome associated with tumors of the parathyroid and neuroendocrine tissues, we developed two screening methods, heteroduplex mutation assay (HMA) and mutation detection gel analysis (MDGA), both based on electrophoretic discrimination of polymerase chain reaction (PCR) products, to detect the mutations. Forty-three genomic DNA samples were used for the evaluation of these techniques. The whole coding region of MEN1 was PCR-amplified with fluorescent primers and then denatured/renatured before electrophoresis on an automated sequencer. 100% of the mutations were detected, subsequently confirmed and identified by sequencing. "Negative" samples were used to evaluate the specificity and reproducibility of the two techniques. The combination of the two methods allows high throughput cost-effective mutation screening which is less laborious than systematic sequencing of the whole coding region of MEN1. Together, these methods provide an efficient screen for MEN1 mutations.     

Theoretical study of binding of tetramethylammonium ion with aromatics

Ab initio computations including correlation have been performed in a comparative study of complexes of tetramethylammonium (TMA) with benzene, pyrrole, pyridine, and imidazole, using polarized Gaussian basis sets of different accuracies. With the best basis (optimized on molecular polarizabilities), the BSSE-corrected binding energies in the most stable complexes of these four ligands are 9.1, 10.7, 13.3, and 16.3 kcal/mol, respectively, with benzene and pyrrole binding in a plane perpendicular to the TMA axis, and pyridine and imidazole inserting their nitrogen lone pair essentially along the TMA axis. The characteristics of secondary sites of binding of benzene are also determined and the overall results are discussed in connection with the possible role of aromatic amino acids in proteins. © 1997 John Wiley & Sons, Inc. J Comput Chem 18 : 2012–2022, 1997     

Sub-aging in a domain growth model

We study analytically the aging dynamics of the O(n) model in the limit of , with conserved and with non-conserved order parameter. While in the non-conserved dynamics, the autocorrelation function scales in the usual way , in the case of a conserved order parameter, `multiscaling' manifests itself in the form , with a relaxation time growing more slowly than the age of the system (sub-aging), and h(t) a function growing faster than any length scale of the problem. In both cases, the effective temperature associated to the violation of the fluctuation theorem tends to infinity in the asymptotic limit of large waiting times. Received 15 May 2000 and Received in final form 5 July 2000     

Tetrahydrofuran analogues with silicon and sulphur atoms

Quantum-mechanical calculations at the self-consistent-field–M?ller–Plesset level have been performed for various compounds obtained by substituting two or four CH₂ groups of the tetrahydrofuran molecule with SiH₂ groups, as well as the oxygen with a sulphur atom. Cyclic tetrasilane oxide, (SiH₂)₄O, and sulphide, (SiH₂)₄S, are suggested as possible alternatives to the carbon ring of natural sugars for the design of exobiological molecules because of certain similarities with tetrahydrofuran, (CH₂)₄O, especially the relatively small energy differences between different conformers and the subsequent ability to cross the energy barriers between them by puckering on the pseudorotation wheel. Received: 16 September 1999 / Accepted: 3 February 2000 / Published online: 21 June 2000     

Theoretical and photophysical study of photoisomerism of cyanine dyes: bisphenylaminopentamethine cyanine (BPPC)

The trans-cis photoisomerism of BPPC was investigated as part of a comprehensive, both theoretical and experimental, study on the photophysical and photochemical properties of cyanines having pentamethine cyanine as a common chromophore. In this work the determination of the trans → cis photoisomerization and thermal back isomerizatkm kinetics in alcohols was combined with CS INDO CI calculations of S₀ and S₁ potential energy curves for the paths leading to mono-cis isomers, where the dielectric solvent effects were taken into account by the simple virtual charge model. In agreement with the indications of a previous steady-state spectroscopy study, it was concluded that irradiation of BPPC into the visible absorption region gives rise to formation of the C(3)–C(4) cis planar isomer, already observed with the parent chromophore (BMPC), and an additional isomer, N(1)-C(2) cis, peculiar to BPPC. The role of the solute-solvent interactions is discussed with reference to the purely intramolecular model previously proposed for the cyanine photoisomerization.     

Lusters of renaissance pottery: Experimental and theoretical optical properties using inhomogeneous theories

Luster decoration of medieval and renaissance potteries constitutes one of the most important and sophisticated decoration techniques of the Mediterranean basin. Lusters consist in a thin layer of silver and copper nanocrystals immersed in a dielectric matrix. Different physical phenomena are responsible for the very brilliant and complex colored effect produced by the lusters. On one hand, according to the thickness of the thin layer, interferential effects occur giving rise to a classical iridescent effect. On the other hand, the nanostructure of the metallic compound leads to extra absorption, generally observed in the visible or near infrared, due to an external resonance associated with the excitation of a surface plasmon in the metallic particles. The position of this resonance, and so the color of the film, depends from many parameters, mainly: (1) the relative volume fraction p of the metal inclusions. (2) The mean size of the metal particle. (3) The shape of the particles and (4) the dielectric functions of the constituents. These two phenomena are not independent as the second one greatly affects the dielectric function of the film and, thus, its optical thickness.In this paper, the physical and optical properties of various lusters from Deruta and Gubbio (Italy) of the XVI century are presented. The structure and the composition of the different films have been determined by scanning electron microscope (SEM), ion beam analyses (PIXE and RBS) and low incidence X-ray diffraction. The optical properties have been determined by two different techniques: (a) hemispherical spectroscopic measurements under near-normal incidence; (b) gonioscopic measurements for a given angle of incidence and wavelength. The first one allows the determination of the effective index of refraction of the inhomogeneous layer, and the second one the determination of the bidirectional reflectance distribution function (BRDF) of the material. PACS 68.55.N; 61.46     

Monitoring protein interactions in the living cell through the fluorescence decays of the cyan fluorescent protein.

Using fluorescence lifetime microspectroscopy and imaging techniques, we have studied the fluorescence of cyan fluorescent protein (CFP) transiently expressed in HEK-293 cells, in the presence or absence of its fluorescence resonance energy transfer (FRET) partner, yellow fluorescent protein (YFP). When the two proteins are attached through a 27-amino-acid linker, a 33 % average efficiency of intramolecular energy transfer is accurately determined inside the cell. Additionally, we observe a systematic quenching of the CFP fluorescence with increasing levels of protein expression. This quenching cannot be accounted for by formation of the previously described dimer of GFP-related proteins, since its magnitude is unchanged when the fluorescent proteins carry the mutation A206K shown to dissociate this dimer in vitro. Even when the intracellular protein concentration largely exceeds the in vitro dissociation constant of the dimer, self-association remains undetectable, either between free proteins or intramolecularly within the CFP-YFP construct. Instead, the detailed concentration effects are satisfactorily accounted for by a model of intermolecular, concentration-dependent energy transfer, arising from molecular proximity and crowding. In the case of CFP alone, we suggest that self-quenching could result from a pseudo-homo FRET mechanism between different, spectrally shifted emissive forms of the protein. These phenomena require careful consideration in intracellular FRET studies.     

Temperature effect on tyre-road noise

Tyre-road noise emission decreases when the outdoor temperature increases, with a variation that can exceed −0.1 dB(A)/°C. This effect depends on tyre-road combination, but semi-generic corrections can improve the accuracy of tyre-road noise measurements. In this paper, the variation of pass-by noise level of a passenger car at 90 km/h with temperature is investigated, on seven types of road surfaces, under different temperature conditions. A good correlation between air, road surface and tyre temperature is outlined. A linear relationship between noise level and air temperature variations is observed for bituminous pavements, of about −0.1 dB(A)/°C, but reduced to −0.06 dB(A)/°C for pavements having porosity. No temperature effect is observed on cement concrete pavements. A spectral analysis shows that the temperature effect is highest in low and high frequency range, what can be explained by generating mechanisms rather than propagation.     

A synthesis of new pyrrolo[3,2‐c]quinolines

A synthesis of pyrrolo[3,2‐c]quinolines substituted in the 7‐ and 8‐ positions by methoxy groups and in the 3‐ position by an amido group is described. The structures were designed to have a crescent shape, a planar fused cyclic moiety with two ortho methoxy groups and ionisable amino or amidinic group at pH 7.