Modulating the activity of oligonucleotides by carbohydrate conjugation: solid phase synthesis of sucrose-oligonucleotide hybrids

In order to expand the repertoire of available oligosaccharide-oligonucleotide hybrids, the on-line solid phase synthesis of oligonucleotides conjugated at the 3'-and/or 5'-end with a preformed disaccharide unit has been performed. The key compound in the synthetic scheme described here is an appropriate phosphoramidite derivative of fully protected sucrose, used in association with a solid support functionalized with DMT-protected sucrose. The sucrose units at both ends of selected oligonucleotide sequences were shown to increase their chemical and enzymatic stability, while not interfering with duplex formation and with the ability of G-rich sequences to adopt a quadruplex structure.     

Optimization strategies for the analysis and purification of drug discovery compounds by reversed-phase high-performance liquid chromatography with high-pH mobile phases

Careful selection of both high-pH mobile phase as well as organic modifier, was performed in order to develop and optimize HPLC conditions for the separation of drug discovery compounds. High-pH mobile phases provide excellent chromatographic resolution and increased mass loading of basic compounds. The analytical methods so defined have been successfully transferred to preparative automated UV-directed purification, an important fact due to the increasing number of samples requiring purification. It should be noted that, the single prerequisite for this approach is an analytical LC-UV-MS run, therefore the system has the ability to collect only fractions likely to contain the target product. A cost-effective strategy for maximizing the purification of drug discovery compounds is proposed.     

Connected monomial invariants

We define the monomial invariants of a projective variety Z; they are invariants coming from the generic initial ideal of Z.We prove that, under suitable hypotheses, a variety of codimension at least two has connected monomial invariants; as a corollary, we generalize a result of Cook [C]: if Z is an integral variety of codimension two, satisfying the hypothesis s_Z=s, then its monomial invariants are connected.The authors are members of CNR–GNSAGA (Italy).During the preparation of this paper the authors were partially supported by National Research Project Geometria sulle varietà algebriche COFIN 2002 of MIUR–Italy.Mathematics Subject Classification (2001): 14M07Acknowledgement The authors had fruitful discussions–either in person or via e-mail–on the topics of this paper with many people, among them Matsumi Amasaki, Iustin Coanda, Wolfram Decker, Mark Green, Francesco Russo, Enrico Sbarra, Enrico Schlesinger, Frank Schreyer; their help is gratefully acknowleged. Last, but by no means least, one of the referees pointed out that our original result, Corollary 2.7, could be significantly enlarged in its scope, thus giving Theorem 2.4.     

A flexible nudged elastic band program for optimization of minimum energy pathways using ab initio electronic structure methods

A driver program for carrying out nudged elastic band optimizations of minimum energy reaction pathways is described. This approach allows for the determination of minimum energy pathways using only energies and gradient information. The driver code has been interfaced with the GAUSSIAN 98 program. Applications to two isomerization reactions and to a cluster model for H(2) desorption from the Si(100)-2 x 1 surface are presented.     

Structure of Escherichia coli dUTPase in Solution: A Small Angle Neutron Scattering Study

The present study investigates shape properties of the enzyme dUTPase from Escherichia coli in the solution phase. In this work small angle neutron scattering (SANS) findings on dUTPase/D₂O solutions for temperature values of T = 8 °C and T = 37 °C are presented. The analysis of SANS data, carried out by using a prolate ellipsoid core/shell model fitting and the well‐known Guinier and Zimm analysis procedures allows the characterization of the shape of the protein in solution. By means of the comparison with experimental and theoretical data existing in literature on dUTPase in the crystalline state, we find that the protein in solution maintains its dimensions before the denaturation process. Furthermore, by analyzing the SANS spectra of dUTPase/D₂O/trehalose solutions, we emphasize the bioprotective effects of trehalose on the protein.

Structure of dUTPase.     

On maximal surfaces in the n-dimensional Lorentz-Minkowski space

Complete maximal surfaces in the n-dimensional Lorentz-Minkowski space are studied from the behaviour of their normal vectors. Moreover, several examples of maximal surfaces are constructed.Research partially supported by DGICYT Grant PS87-0115-C03-02.     

Generalized Maxwell's equations and quantum mechanics. II. Generalized dirac equation

The bare field approximation, in which the results of a recent paper were deduced, is removed. A generalized Dirac equation is obtained. The bare field, in the absence of sources, is identified with the field associated with the neutrino.     

Radical anions of fullerene bisadducts: a multifrequency CW-EPR study

The radical anions of three C₆₀ bisadducts (from now on termed CIS1, CIS2, and CIS3) have been studied in liquid solution and glassy matrix by X-band and high frequency CW-EPR spectroscopy. The three adducts CIS1, CIS2, and CIS3 are characterized by a pyrrolidinic ring and an isoxazolinic ring in position cis1-O, cis2-C, and cis3-C, respectively; the two rings are connected by a methylenic chain. In the X-band spectra of CIS1, one species has been observed showing hyperfine coupling constants with the pyrrolidinic nitrogen and ¹³C nuclei, whereas in the X-band spectra of CIS2 and CIS3 more species are apparent, some with and other without hyperfine coupling with the pyrrolidinic ¹⁴N. High field spectra at 110 and 220 GHz for all the bisadducts have been obtained; in all the cases, more species are evident with small differences in the g-factors. The occurrence of more species are discussed and put in relation with different bisadduct conformations. Furthermore, on the basis of the mechanism proposed for the ¹⁴N hcc in previously studied fulleropyrrolidine (FP) monoanions, the presence or absence of ¹⁴N hcc for CIS1 and the different conformations of CIS2 and CIS3 is discussed. The temperature dependence of the EPR linewidths and the g-factors of all the species have been determined and discussed in term of the different structural stiffness and symmetry of the three bisadducts.     

Recovery of three-dimensional shapes by using defocused structured light

We present a new concept for three-dimensional shape recovery using defocused structured light (DSL) images. The DSL technique externally extracts the depth information from the scene by using projections of cylindrical wavefronts on the object. These projections show different degrees of defocus as a function of the depth. Efficient algorithms for shape recovery are developed taking advantage of the spatial regularity of the projected light and the profile of each fringe. In this way a depth map of the scene is obtained using only one image. Experimental results are shown and we discuss the possibility of a real time implementation.