Structural and symptomatic efficacy of glucosamine and chondroitine sulfate in osteoarthritis: a comprehensive meta-analysis

in Arthritis and Rheumatism (2003, September), 48(number 9 (suppl.)), 214

Structural and vibrational study of the negative thermal expansion in liquid As2Te3

in Physical Review. B, Condensed Matter and Materials Physics (2010), 82(5), 0542029-05420290542029

We present an experimental and theoretical study of liquid As 2Te 3. This alloy exhibits a negative thermal expansion (NTE) in a 250 K range above the melting temperature T m = 654 K. We evidence the ... [more ▼]

We present an experimental and theoretical study of liquid As 2Te 3. This alloy exhibits a negative thermal expansion (NTE) in a 250 K range above the melting temperature T m = 654 K. We evidence the changes in As 2Te 3 structure by measuring neutron-diffraction spectra at five temperatures in the NTE range and perform first principles molecular dynamics simulations at the same temperatures and densities to study the local order evolution in the liquid. Our calculated structures show an increase in the coordination numbers and a symmetrization of the first neighbors shell around atoms when the temperature rises. To confirm these results, we performed inelastic neutron scattering to obtain the vibrational density of state (VDOS) along the NTE. We see a clear change in the VDOS, consisting in a redshift of the highest frequencies with temperature. Finally, electrical conductivity evolution was obtained from the simulated structures, to compare with the semiconductor to metal transition measured experimentally. [less ▲]

A Structural Balance Sheet Model of Sovereign Credit Risk

in Finance (2011), 1(2), 293-321

This paper studies sovereign credit spreads using a contingent claims model and a balance sheet representation of the sovereign economy. Analytical formulae for domestic and external debt values as well ... [more ▼]

This paper studies sovereign credit spreads using a contingent claims model and a balance sheet representation of the sovereign economy. Analytical formulae for domestic and external debt values as well as for the financial guarantee are derived in a framework where recovery rate is endogenously determined as the solution of a strategic bargaining game. The approach allows to relate sovereign credit spreads to observable macroeconomic factors, and in particular accounts for contagion effects through the corporate and banking sectors. Pricing performance as well as predictions about credit spread determinants are successfully tested on the Brazilian economy. [less ▲]

Structural basis for the broad-spectrum inhibition of metallo-beta-lactamases by thiols

in Organic & Biomolecular Chemistry (2008), 6(13), 2282-2294

The development of broad-spectrum metallo-beta-lactamase (MBL) inhibitors is challenging due to structural diversity and differences in metal utilisation by these enzymes. Analysis of structural data ... [more ▼]

The development of broad-spectrum metallo-beta-lactamase (MBL) inhibitors is challenging due to structural diversity and differences in metal utilisation by these enzymes. Analysis of structural data, followed by non-denturing mass spectrometric analyses, identified thiols proposed to inhibit representative MBLs from all three sub-classes: B1, B2 and B3. Solution analyses led to the identification of broad spectrum inhibitors, including potent inhibitors of the CphA MBL (Aeromonas hydrophila). Structural studies revealed that, as observed for other B1 and B3 MBLs, inhibition of the L1 MBL thiols involves metal chelation. Evidence is reported that this is not the case for inhibition of the CphA enzyme by some thiols; the crystal structure of the CphA-Zn-inhibitor complex reveals a binding mode in which the thiol does not interact with the zinc. The structural data enabled the design and the production of further more potent inhibitors. Overall the results suggest that the development of reasonably broad-spectrum MBL inhibitors should be possible. [less ▲]

Structural basis for the interaction of lactivicins with serine beta-lactamases.

in Journal of Medicinal Chemistry (2010), 53(15), 5890-4

Lactivicin (LTV) is a natural non-beta-lactam antibiotic that inhibits penicillin-binding proteins and serine beta-lactamases. A crystal structure of a BS3-LTV complex reveals that, as for its reaction ... [more ▼]

Lactivicin (LTV) is a natural non-beta-lactam antibiotic that inhibits penicillin-binding proteins and serine beta-lactamases. A crystal structure of a BS3-LTV complex reveals that, as for its reaction with PBPs, LTV reacts with the nucleophilic serine and that cycloserine and lactone rings of LTV are opened. This structure, together with reported structures of PBP1b with lactivicins, provides a basis for developing improved lactivicin-based gamma-lactam antibiotics. [less ▲]

Structural basis of hemadsorbing sites during the formation of syncytia in measles-infected cells

in Journal of Cell Biology (1977), 75

The surfaces of cells Infected with measles virus adsorb monkey red blood cells (RBC). In this study, the structure and localization of viral hemadsorbing (HAD) sites and their relationship with antigenic ... [more ▼]

The surfaces of cells Infected with measles virus adsorb monkey red blood cells (RBC). In this study, the structure and localization of viral hemadsorbing (HAD) sites and their relationship with antigenic sites and with cell fusion were investigated in measles virus infected Vero cells. Transmission and scanning electron microscopy were combined with immunolabeling, using human anti-measles IgG (Ab) and protein A from Staph, aureus coupled to peroxidase.. In the early syncytia (50-100 2 in diameter), HAD sites were clustered in the center but scattered at the periphery. In contrast, mature giant cells (400 to 500 2) had all HAD sites in the central area which displayed scattered villi. The periphery of the mature giant cells and the mononucleated cells did not hemadsorb but were covered with numerous villi. In the central area, RBC were firmly attached to villi and ridges over nucleocapsids but rarely to viral buds. Villi and ridges under the RBC were covered with antigenic sites which were not detected at the periphery of the mature syncytia. When living cells were treated with Ab at 4°C, complete inhibition of hemadsorption was only observed when RBC were applied to the cells in the cold. In other experiments, cells reacted with Ab at 4°C were washed, brought to 37°C and treated with RBC immediately or after 1-24 hrs. After 1-2 hrs, some HAD sites were present only at the periphery of immature giant cells, suggesting that RBC receptors had already emerged in membrane areas where fusion started again. After 24 hrs, the distribution of HAD and antigenic sites was the same as on cells not exposed to Ab. It seems that when fusion begins, HAD sites appeared on the periphery of the syncytia and then move spontaneously towards the center. With cessation of fusion, HAD sites disappear from the periphery of the giant cell. Receptors for RBC are closely associated with antigenic sites and correlated with viral induced fusion but not with virus production. [less ▲]

Structural basis of the actin-calponin homology domain interaction.

in Biophysical Journal (2005), 88(1), 497-497

Structural basis of the inhibition of class A beta-lactamases and penicillin-binding proteins by 6-beta-iodopenicillanate

in Journal of the American Chemical Society (2009), 131(42), 15262-15269

6-Beta-halogenopenicillanates are powerful, irreversible inhibitors of various beta-lactamases and penicillin-binding proteins. Upon acylation of these enzymes, the inhibitors are thought to undergo a ... [more ▼]

6-Beta-halogenopenicillanates are powerful, irreversible inhibitors of various beta-lactamases and penicillin-binding proteins. Upon acylation of these enzymes, the inhibitors are thought to undergo a structural rearrangement associated with the departure of the iodide and formation of a dihydrothiazine ring, but, to date, no structural evidence has proven this. 6-Beta-iodopenicillanic acid (BIP) is shown here to be an active antibiotic against various bacterial strains and an effective inhibitor of the class A beta-lactamase of Bacillus subtilis BS3 (BS3) and the D,D-peptidase of Actinomadura R39 (R39). Crystals of BS3 and of R39 were soaked with a solution of BIP and their structures solved at 1.65 and 2.2 A, respectively. The beta-lactam and the thiazolidine rings of BIP are indeed found to be fused into a dihydrothiazine ring that can adopt two stable conformations at these active sites. The rearranged BIP is observed in one conformation in the BS3 active site and in two monomers of the asymmetric unit of R39, and is observed in the other conformation in the other two monomers of the asymmetric unit of R39. The BS3 structure reveals a new mode of carboxylate interaction with a class A beta-lactamase active site that should be of interest in future inhibitor design. [less ▲]

Structural Behavior of Concrete Columns under Natural Fires including Cooling Down Phase

in Barros, Helena; Faria, Rui; Pina, Carlos (Eds.) et al Proceedings of The International Conference on Recent Advances in Nonlinear Models - Structural Concrete Applications (2011, November)

This study deals with the structural behavior of concrete columns subjected to natural fire, with special focus on the cooling down phase. As the reliability of the numerical simulations largely depends ... [more ▼]

This study deals with the structural behavior of concrete columns subjected to natural fire, with special focus on the cooling down phase. As the reliability of the numerical simulations largely depends on the validity of the constitutive models that are used, this issue is addressed in details in the first part of the paper. It is found that the current concrete model of Eurocode may not be adapted for representing the behavior of concrete during a cooling phase because the effects of transient creep are incorporated implicitly in the mechanical strain term. A formulation of the Eurocode concrete model that contains an explicit term for transient creep strain has been developed and, after implementation in the software SAFIR, it was used for the numerical simulations presented in this paper. In its second part, the study gives an insight into the possibility of collapse of reinforced concrete columns during and after the cooling phase of the natural fire. It is found that failure during the cooling phase of a fire is a possible event and, more dangerous, that a failure of the concrete columns is still possible when the fire has been completely extinguished. The main mechanisms that lead to this type of failure are found to be the delayed increase of temperature in the central zones of the element and the additional loss of concrete strength during the cooling phase of the fire. A parametric study shows that the most critical situations with respect to delayed failure arise for short fires and for columns with low slenderness or massive sections. The numerical analyses have been performed also with the concrete model of Eurocode and the results also show a risk of delayed collapse. Yet, the occurrence of collapse during or after the cooling phase is predicted more often with the explicit creep model than with the implicit model of Eurocode, which suggests that the way the transient creep effects are handled in the Eurocode model may lead to unsafe results when considering the cooling phase of a fire. [less ▲]

Structural characterization of isobar selenium containing contaminant in a commercially available selenomethionine standard using electrospray – Ion Mobility Time of Flight Mass Spectrometry

Poster (2011, April)