Synthesis of novel 5-aryl-6-cyano-3H,8H-pyrido[2,3-d]pyrimidine-4,7-diones in the reaction of 6-amino-4-pyrimidinones with benzaldehyde and ethyl cyanoacetate

The title compounds 4 and 5 have been prepared in one-step reaction from 6-amino-4-pyrimidinones 1 , the corresponding 4-substituted benzaldehyde 2 and ethyl cyanoacetate 3 in very good yields. The structure of the final compounds was determined on the basis of nmr measurements, especially by ¹H, ¹H-, ¹H,¹³C COSY, and DEPT.     

Multielemental trace analysis of biological materials using double focusing inductively coupled plasma mass spectrometry detection

The analytical potential of double focusing-inductively coupled plasma-mass spectrometry (DF-ICP-MS) for total elemental analysis in clinical samples (serum, blood, urine and other biological fluids), tissues and food products is illustrated by reviewing typical applications recently published. Also, the use of DF-ICP-MS as specific detector for trace element speciation in biological samples is discussed. After adequate separation of interferences in the chromatographic column, low resolution measurements (R = 300) can be used to provide enhanced sensitivities of more than 100 times compared with quadrupole-inductively coupled plasma-mass spectrometry (Q-ICP-MS). This capability is extremely valuable in speciation studies. Also, the use of DF-ICP-MS at low resolution could provide very precise isotope ratio measurements for isotope dilution analysis due to the ‘flat topped’ peaks obtained at this resolution. Unfortunately, the literature on these last two issues is rather scarce so far, in spite of their extremely high analytical possibilities for biological research. Moreover, the bright future of DF-ICP-MS as a most powerful multielemental detector for trace element applications in biological systems will be highlighted. Apart from applications detailed above other important application fields can be envisaged. In particular, we will speculate on its possible use to confirm/establish ‘reference values’ of trace element content in ‘normal’ populations and so to help to diagnose health and disease status, related with trace element total content or their speciation in clinical specimens.     

Moment Solutions for the State Exiting Counting Processes of a Markov Renewal Process

Important performance measures for many Markov renewal processes are the counts of the exits from each state. We present solutions for the conditional first, second, and covariance moments of the state exiting counting processes for a Markov renewal process, and solutions for the unconditional equilibrium versions of the moments. We demonstrate the relationship between the conditional first moments for the state exiting and the state entering counting processes. For analytical and illustrative purposes, we concentrate on the two state case. Two asymptotic expansions for the moment functions are proposed and evaluated both analytically and empirically. The two approximations are shown to be competitive in terms of absolute relative error, but the second approximation has a simpler analytical form which is useful in analyzing more complex stochastic processes having an underlying MRP structure.     

Cooperative stabilisation of 14-3-3σ protein–protein interactions via covalent protein modification

14-3-3 proteins are an important family of hub proteins that play important roles in many cellular processes via a large network of interactions with partner proteins. Many of these protein–protein interactions (PPI) are implicated in human diseases such as cancer and neurodegeneration. The stabilisation of selected 14-3-3 PPIs using drug-like ‘molecular glues’ is a novel therapeutic strategy with high potential. However, the examples reported to date have a number of drawbacks in terms of selectivity and potency. Here, we report that WR-1065, the active species of the approved drug amifostine, covalently modifies 14-3-3σ at an isoform-unique cysteine residue, Cys38. This modification leads to isoform-specific stabilisation of two 14-3-3σ PPIs in a manner that is cooperative with a well characterised molecular glue, fusicoccin A. Our findings reveal a novel stabilisation mechanism for 14-3-3σ, an isoform with particular involvement in cancer pathways. This mechanism can be exploited to harness the enhanced potency conveyed by covalent drug molecules and dual ligand cooperativity. This is demonstrated in two cancer cell lines whereby the cooperative behaviour of fusicoccin A and WR-1065 leads to enhanced efficacy for inducing cell death and attenuating cell growth.

The aminothiol WR-1065 covalently modifies 14-3-3σ to stabilse its interactions with p53 and ERα. It enhances the effect of fusicoccin A via a cooperative mechanism that leads to 14-3-3 partner-protein specific activty against cancer cells.      

Deformation Driven Homogenization of Fracturing Solids

The paper discusses numerical formulations of the homogenization for solids with discrete crack development. We focus on multi–phase microstructures of heterogeneous materials, where fracture occurs in the form of debonding mechanisms as well as matrix cracking. The definition of overall properties critically depends on the developing discontinuities. To this end, we extend continuous formulations [1] to microstructures with discontinuities [2]. The basic underlying structure is a canonical variational formulation in the fully nonlinear range based on incremental energy minimization. We develop algorithms for numerical homogenization of fracturing solids in a deformation–driven context with non–trivial formulations of boundary conditions for (i) linear deformation and (ii) uniform tractions. The overall response of composite materials with fracturing microstructures are investigated. As a key result, we show the significance of the proposed non–trivial formulation of a traction–type boundary condition in the deformation–driven context. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Basic Sequences in the Dual of a Fréchet Space

In this paper we study some properties of basic sequences in the dual of a Fréechet space. As a consequence we obtain that if E is a Fréechet space with the property that for each closed subspace F of E and each bounded subset B of E/F there is a bounded subset A of E with φ(A) = B, where φ denotes the canonical surjection of E onto E/F, then one of the following conditions is at least satisfied: 1. E is a Banach space, 2. E is a Schwartz space, 3. E is the product of a Banach space by ω. Finally, we also obtain some results concerning totally reflexive spaces.     

Lipid-mimicking phosphorus-based glycosidase inactivators as pharmacological chaperones for the treatment of Gaucher's disease

Gaucher''s disease, the most prevalent lysosomal storage disorder, is caused by missense mutation of the GBA gene, ultimately resulting in deficient GCase activity, hence the excessive build-up of cellular glucosylceramide. Among different therapeutic strategies, pharmacological chaperoning of mutant GCase represents an attractive approach that relies on small organic molecules acting as protein stabilizers. Herein, we expand upon a new class of transient GCase inactivators based on a reactive 2-deoxy-2-fluoro-β-d-glucoside tethered to an array of lipid-mimicking phosphorus-based aglycones, which not only improve the selectivity and inactivation efficiency, but also the stability of these compounds in aqueous media. This hypothesis was further validated with kinetic and cellular studies confirming restoration of catalytic activity in Gaucher cells after treatment with these pharmacological chaperones.

Engineered 2-fluoroglucosides containing a phosphorus-based leaving group rapidly form a stable covalent intermediate with GCase, thus stabilising the enzyme during transit to the lysosome, where it is released on a clinically appropriate timescale.     

Synthesis and Photochromic Behaviour of Novel 2H‐1‐Benzopyrans (=2H‐Chromenes) Derived from Carbazololes

The synthesis and photochromic properties of new 2,2‐diphenyl‐2H‐1‐benzopyrans, fused to an indole moiety, are described. All compounds exhibit photochromic behaviour in solution at room temperature. The heteroanellation effects are variable and depend on the position and geometry of the fused indole moiety. A general bathochromic shift in the spectra of the open forms is observed. The presence of a N‐methyl group prevents the broadening of the absorption spectra and promotes the instability of some photoinduced forms of compounds with the indole moiety fused at the 5,6 positions of the 2H‐1‐benzopyran skeleton. The enhanced photocolouration efficiency in the near‐UV and the kinetics of thermal bleaching indicate that the novel compounds with an indole moiety fused at the 6,7 positions, particularly those with a linked thiophene moiety, are very interesting molecules for applications in the field of variable optical absorption systems.     

Spiro[4.4]nonatetraene and its Positive and Negative Radical Ions: Molectronic Structure Investigations

The electronic structure of spiro[4.4]nonatetraene 1 as well as that of its radical anion and cation were studied by different spectroscopies. The electron‐energy‐loss spectrum in the gas phase revealed the lowest triplet state at 2.98 eV and a group of three overlapping triplet states in the 4.5 – 5.0 eV range, as well as a number of valence and Rydberg singlet excited states. Electron‐impact excitation functions of pure vibrational and triplet states identified various states of the negative ion, in particular the ground state with an attachment energy of 0.8 eV, an excited state corresponding to a temporary electron attachment to the 2b₁ MO at an attachment energy of 2.7 eV, and a core excited state at 4.0 eV. Electronic‐absorption spectroscopy in cryogenic matrices revealed several states of the positive ion, in particular a richly structured first band at 1.27 eV, and the first electronic transition of the radical anion. Vibrations of the ground state of the cation were probed by IR spectroscopy in a cryogenic matrix. The results are discussed on the basis of density‐functional and CASSCF/CASPT2 quantum‐chemical calculations. In their various forms, the calculations successfully rationalized the triplet and the singlet (valence and Rydberg) excitation energies of the neutral molecule, the excitation energies of the radical cation, its IR spectrum, the vibrations excited in the first electronic absorption band, and the energies of the ground and the first excited states of the anion. The difference of the anion excitation energies in the gas and condensed phases was rationalized by a calculation of the Jahn‐Teller distortion of the anion ground state. Contrary to expectations based on a single‐configuration model for the electronic states of 1 , it is found that the gap between the first two excited states is different in the singlet and the triplet manifold. This finding can be traced to the different importance of configuration interaction in the two multiplicity manifolds.