759 research outputs found
Post-stroke depression: research methodology of a large multicentre observational study (DESTRO)
No full textThe heterogeneity of published data regarding post-stroke depression (PSD) prompted an Italian multicenter observational study (DESTRO), which took place in 2000-2003. The investigation involved 53 Italian neurology centers: of these, 50 treat acute patients and 3 provide rehabilitation care; 21 centres are in Northern Italy, 20 are in Central Italy, and 12 are in Southern Italy. The time schedule was articulated into three phases: registration of 6289 stroke patients; selection of 1817 cases and enrollment of 1074 patients; and follow-up for two years (1064 patients). Mood assessment was performed by evaluating depressive symptoms according to DSM IV and the Beck depression inventory (visual analog mood scale for aphasic patients). Depressed patients were also administered the Montgomery-Asberg depression rating scale. Scores were related to function (Barthel index, modified Rankin scale), cognition (MMSE), quality of life (SF-36), and clinical data. Data analysis will provide information on PSD prevalence, onset and evolution, correlation with ischemic clinical syndrome, impact on activities of daily living, cognitive level and quality of life. The few data available at the present time concern PSD prevalence in the first six months after stroke (33.6%). DESTRO is a longitudinal investigation of a large patient sample and is expected to provide insights into the relationship of PDS with the functional and clinical consequences of stroke
Experimental and theoretical charge density study of an antimalarial drug
No full textMalaria, an infection caused by the Plasmodium Falciparum protozoa, is nowadays one of the most lethal parasitic disease. As the Plasmodium protozoon is becoming resistant to quinoline-based molecules, the development of new drugs and the understanding of the key chemical features for their activity and of their mechanism of action is of great importance. In this context, we carried out a thorough analysis on the antimalarial drug dihydroartemisinin (DHA, Figure 1), through the study of its experimental and theoretical charge density (CD) distributions.[1]
The experimental CD has been obtained by a single-crystal X-ray diffraction experiment at T = 100 K on a Bruker SMART APEX II diffractometer equipped with a CCD area detector, while the corresponding theoretical CD has been derived through fully periodic single point DFT calculations at the experimental geometry.
We have identified nucleophilic as well as electrophilic regions of the molecule by analyzing its electrostatic potential and investigated the crystal packing and the change in the CD distribution moving from the isolated molecule to the crystal. Several CD analysis tools, with special emphasis on the Quantum Theory of Atoms in Molecules (QTAIM) [2], have been adopted, with the aim of fully characterize the chemical nature of specific functional groups, such as the peroxide group and the polyether chain.
We have also performed geometry optimizations on deprotonated and radical anion of DHA, the latter being the intermediate species in most of the proposed antimalarial modes of action of the drug.
[1] G. Saleh, R. Soave, L. Lo Presti, R. Destro Chem. Eur. J. 2013, 19, 3490.
[2] R. F. W. Bader Atoms in Molecules: A Quantum Theory Oxford University Press, Oxford, 1990
Lab-on-a-chip and integrated strategies in tumor immunotheraphy
No full textBackground
While conventional chemotherapy and radiation therapy have improved the survival of many cancer patients, there are still major disadvantages associated with these treatments such as high toxicity and drug-resistance. The possibility to manipulate the immune system to recognize and kill tumor cells is very attractive despite numerous obstacles remaining to be overcome. In particular, the ability of the immune system to destroy disseminated metastases in a specific way makes immunotherapy an attractive alternative to conventional therapies. Nevertheless, other unconventional technologies emerged in recent years seem to be very promising; in particular the analysis and monitoring of single cell-to-cell interactions and the capability to individually control single cells by Lab-on-a-chip devices have become of great interest in different areas of life sciences. These new technologies, in combination with progresses reached in anti-tumor vaccines, could be useful to improve immune T cell responses against tumor antigen for a more efficient immunotherapy.
Aims
This thesis focuses on two tumor immunotherapy issues: 1) design, realization and validation of innovative Lab-on-a-chip devices for immune system study, that allows single tumor cell and effector cell interaction, detection and isolation; 2) identification of molecular mechanisms that prevent EBV-associated tumors (e.g. Burkitt’s lymphoma) recognition by T cells and study of their potential correction by specific treatments. The main goal of this study remains indeed the evaluation of an integrated strategy for immunotherapy development enhancing for malignancies treatment.
Methods
Biocompatibility test, generation of memory CTL cultures, 51Cr release assay, IFN-Elispot, proteasomes purification, western blot assay, enzymatic assay, immunofluorescence, RT-PCR.
Main Results
As concerns the first part of the thesis, a main achievement was the design of Lab-on-a-chip platform that combined microfluidics and electronics together, consisting in a matrix of
up to thousand microwells where living cells can be deposited. Subsequently, different materials have been evaluated to identify the most biocompatible ones for biosensor manufacturing. Once developed Lab-on-a-chip prototype, it has been tested from a functional point of view. In particular, it has been demonstrated that the biosensor is able to isolate and trap single cells inside microwells by dielectrophoresis, that recovered cells are still alive and that their biological functions and gene expression remain unaltered. Furthermore, tumor cell lysis by immune effector cells could be successfully monitored inside device microwells, showing that biosensor could be used for cell to cell interaction studies.
Regarding the second aim of this thesis, it has been identified a new epitope-specific T cell response against EBV nuclear antigen 1 (EBNA1). It has also been demonstrated that CTLs specific for another EBNA1-derived epitope (referred as HPV) are detectable in the majority of HLA-B35 individuals, and recognize EBV-transformed B lymphocytes (LCL) but not Burkitt’s lymphoma (BL). Afterwards LCL and BL have been compared for their antigen processing machinery, demonstrating that one of the major differences was at the proteasome level; indeed, proteasomes from BL cells have displayed a far lower chymotryptic and tryptic-like activities. Interestingly, it has also been shown that treatment with proteasome inhibitors partially restored the capacity of BL cells to present the HPV epitope.
Conclusions
The results achieved in single cell manipulation and cell to cell analysis interaction by Lab-on-a-chip technology, and the findings reached to improve BL immune recognition, represent an implementation of innovative tools that could allow important progresses in cancer diagnosis and immunotherapy
Experimental and theoretical charge density distribution of the colossal magnetoresistive transition metal sulfide FeCr2S4
No full textThe total charge density distribution rho(r) of the colossal magnetoresistive transition metal sulfide FeCr2S4 was evaluated through a multipole formalism from a set of structure factors obtained both experimentally, by means of single crystal high-quality x-ray diffraction data collected at T=23 K, and theoretically, with an extended-basis unrestricted Hartree-Fock periodic calculation on the experimental geometry. A full topological analysis, followed by the calculation of local energy
density values and net atomic charges, was performed using the quantum theory of atoms in molecules. The experimental and theoretical results were compared. Good agreement was found for the topological properties of the system, as well as for the atomic net charges and the nature of the chemical bonds. An analysis of the electron density rho(r), its Laplacian L(r), and the total energy density H(r) at the bond critical points was employed to classify all the interactions that resulted as predominantly closed shell (ionic) in nature. The topological indicators of the bonded interactions for Fe are distinct from those for Cr. The Fe–S bond distances were found to be 0.145 Å shorter than the ideal values computed on the basis of Shannon’s crystal radii, much shorter than the Cr–S distances with respect to their ideal Shannon lengths. Concomitantly, rho(r) and H(r) at the bond critical points are greater for Fe–S interactions, indicating that the local concentration of charge density in the internuclear region is larger for the tetrahedrally coordinated iron than for the octahedrally coordinated chromium. The isosurface in the real space for L(r)=0 was plotted for both iron and chromium, pointing out the local zones of valence shell charge concentration and relating them to the partial d-orbital occupancy of the two transition metal atoms
On the interplay between CH...O and OH...O interactions in determining crystal packing and molecular conformation : an experimental and theoretical charge density study of the Fungal Secondary Metabolite Austdiol (C12H12O5)
No full textThe total exptl. electron d. r(r), its Laplacian .del.2r(r), the mol. dipole moment, the electrostatic potential j(r), and the intermol. interaction energies have been obtained from an extensive set of single-crystal X-ray diffracted intensities, collected at T= 70(1) K, for the fungal metabolite austdiol (1). The exptl. results have been compared with theor. densities from DFT calcns. on the isolated mol. and with fully periodic calcns. The crystal structure of (1) consists of zigzag ribbons extended along one cell axis and formed by mols. connected by both OH...O and CH...O interactions, while in a perpendicular direction, adjacent mols. are linked by short CH...O intermol. contacts. An extensive, quant. study of all the intra- and intermol. H...O interactions, based not only on geometrical criteria, but also on the topol. anal. of r(r), as well as on the evaluation of the pertinent energetics, allowed us (i) to assess the mutual role of OH...O and CH...O interactions in detg. mol. conformation and crystal packing; (ii) to identify those CH...O contacts which are true hydrogen bonds (HBs); (iii) to det. the relative hydrogen bond strengths. An exptl., quant. evidence is given that CH...O HBs are very similar to the conventional OH...O HBs, albeit generally weaker. The comparison between exptl. and theor. elec. dipole moments indicates that a noticeable charge rearrangement occurs upon crystn. and shows the effects of the mutual cooperation of HBs in the crystal. The total intermol. interaction energies and the electrostatic energy contribution obtained through different theor. methods are reported and compared with the exptl. results. It is found that the new approach proposed by Spackman, based on the use of the promol. charge d. to approx. the penetration contribution to intermol. electrostatic energies, predicts the correct relative electrostatic interaction energies in most of the cases
Physicochemical properties of zwitterionic L- and DL-alanine crystals from their experimental and theoretical charge densities
No full textThe total experimental electron density distributions p(r) of zwitterionic L- and DL-alanine crystals, as derived from extensive sets of X-ray diffracted intensities collected at 23 and 19 K, are compared to gain an insight into the different physical properties of the two related chiral compounds in the solid state and to explore the extent of the p(r) transferability. Relevant parameters that characterize the two crystal forms are obtained, showing differences and similarities in terms of (i) geometric descriptors, (ii) topological indexes, (iii) molecular electrostatic potential Φ(r) distributions, (iv) atomic volumes and charges, (v) molecular electric moments, and (vi) electrostatic interaction energies. To assess the relative stability of the racemate with respect to the pure enantiomer, the crystal lattice energies, as obtained through DFT fully periodic calculations, are also discussed and compared with the experimental sublimation enthalpies after correction for the proton-transfer energies. In-crystal group charges, evaluated with the quantum theory of atoms in molecules, are found to be transferable between the racemic and the pure enantiomer, at variance with group volumes. Similarly, molecular first and third moments are not strictly transferable and indicate that for the zwitterionic alanine molecule the molecular charge distribution in the DL-crystal is more polarized in the c direction by about 10%. By contrast, quantitative agreement is observed for second and fourth moments. Significant differences arise from (1) the crystal packing of the dipole vectors, which are aligned in an antiparallel fashion in the L-crystal, to be compared with a parallel alignment in the racemate, due the polar space group Pna21 of the latter, (2) the strongly attractive electrostatic energy of a homochiral pair in the L-crystal, which is opposed to the corresponding heterochiral pair in the DL-crystal form. The difference between these Ees values amounts to 135-150 kJ mol-1. Despite this, the two crystal forms are predicted as equally thermodynamically favored by the theoretical P-B3LYP estimates of the crystal lattice energies. Finally, the necessity of an upgrading of the dispersion and exchange-repulsion terms currently adopted within the experimental charge density approach to intermolecular interactions is recognized and discussed
Approximate anisotropic displacement parameters for H atoms in molecular crystals
No full textAnisotropic displacement parameters for H atoms in molecular crystals are calculated with a simplified model that uses approximate vibrational modes, neglecting correlations between internal and external contributions to the mean square motions. These calculated values agree within a few esds with the ones obtained from neutron diffraction; used in charge density multipolar refinements against X-ray diffraction data, they yield electron densities and derived electrostatic properties that are more accurate than the ones obtainable with the traditional isotropic description. For example, electric field gradients at the H nuclei of L-Alanine are in quantitative agreement with Nuclear Quadrupole Resonance results
Progress in the understanding of drug-receptor interactions, Part 1 : Experimental charge-density study of an angiotensin II receptor antagonist (C30H30N6O3S) at T=17K
No full textAn experimental study of the electron-density distribution rho(r) in an angiotensin II receptor antagonist 1 has been made on the basis of single-crystal X-ray diffraction data collected at a low temperature. The crystal structure of 1 consists of infinite ribbons in which molecules are connected by an N-H center dot center dot center dot N hydrogen bond and several interactions of the CH center dot center dot center dot O, C-H center dot center dot center dot N, and C-H center dot center dot center dot S type. The molecular conformation, characterized by the syn orientation of a tetrazole and a pyrimidinone ring with respect to a phenyl spacer group, is stabilized by two short S center dot center dot center dot O and S center dot center dot center dot N intramolecular contacts between a substituted thiophene fragment and the other two heterocycles of 1. The electrostatic nature of these teractions is documented. Furthermore, the Laplacian of rho(r) in the plane defined by the sulfur, oxygen, and nitrogen atoms involved in these interactions shows their strongly directional character as the regions of charge concentration on the valence shell of the nitrogen and oxygen atoms directly face the regions of charge depletion on the valence shell of the sulfur atom. All the chemical bonds and the relevant intra- and intermolecular interactions of 1 have been quantitatively described by the topological analysis of rho(r). Simple relationships between the bond path lengths (R-b) and the values of rho at the bond critical points (rho(hcp)) have been obtained for the 28 C-C bonds, the seven N-C bonds, and the four O-C bonds. For the first two classes of bonds the relationship is in the form of a straight line, whose parameters, for the C-C bonds, agree, within experimental uncertainty, with those previously derived in our laboratory from a 19 K X-ray diffraction study of crystals of a different compound. Maps of the molecular electrostatic potential phi(r) derived from the experimental charge density display features that are important for the drug-receptor recognition of 1
“I fear the secrets of time”. Excerpts from Sogar Papageien überleben uns
No full textPresented here, in the Italian translation by Elisa Destro, are several excerpts from the novel Sogar Papageien überleben uns (2010) by German-Russian author Olga Martynova.Si presentano qui, nella traduzione italiana di Elisa Destro, alcuni estratti dal romanzo Sogar Papageien überleben uns (2010) dell\u27autrice russo-tedesca Olga Martynova
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