Scaling behaviour in the truncated Zel'dovich approximation

Summary We analyse the scaling properties of the matter distribution generated by the truncated Zel'dovich approximation (TZA) for a universe dominated by a mixture of cold+hot non-baryonic dark matter. At the present epoch, the dark-matter distribution generated by TZA displays an intermediate scaling behaviour between about 4 and 60h ⁻¹ Mpc with a correlation dimensionD _q∼2 forq≥2. The possible implications of these results are considered.     

Plant polyphenols and their anti-cariogenic properties: a review

Polyphenols constitute one of the most common groups of substances in plants. Polyphenolic compounds have been reported to have a wide range of biological activities, many of which are related to their conventional antioxidant action; however, increasing scientific knowledge has highlighted their potential activity in preventing oral disease, including the prevention of tooth decay. The aim of this review is to show the emerging findings on the anti-cariogenic properties of polyphenols, which have been obtained from several in vitro studies investigating the effects of these bioactive molecules against Streptococcus mutans, as well as in vivo studies. The analysis of the literature supports the anti-bacterial role of polyphenols on cariogenic streptococci, suggesting (1) a direct effect against S. mutans; (2) an interaction with microbial membrane proteins inhibiting the adherence of bacterial cells to the tooth surface; and (3) the inhibition of glucosyl transferase and amylase. However, more studies, particularly in vivo and in situ, are necessary to establish conclusive evidence for the effectiveness and the clinical applications of these compounds in the prevention of dental caries. It is essential to better determine the nature and distribution of these compounds in our diet and to identify which of the hundreds of existing polyphenols are likely to provide the greatest effects.     

Antimicrobial phenalenone derivatives from the marine-derived fungus Coniothyrium cereale

The marine-derived fungus Coniothyrium cereale was isolated from the green alga Enteromorpha sp. and found to produce the new phenalenone derivatives 1-7 as well as the known compounds lactone 8, (-) sclerodin (9), lamellicolic anhydride (10), (-) scleroderolide (11), and (-) sclerodione (12). The structures of these closely related compounds were established from extensive spectroscopic investigations on the basis of one and two dimensional NMR spectroscopic studies ((1)H, (13)C, COSY, NOESY, HSQC and HMBC) as well as mass spectrometric analysis (LC/MS, HREIMS and HRESIMS), UV and IR spectra. Compounds 5 and 11 showed the same antimicrobial activity toward Staphylococcus aureus SG 511 with an MIC value of 24 μM. The presence of a diketo-lactone ring as in compounds 5 and 11 was found to be essential for this activity. In agar diffusion assays with Mycobacterium phlei considerable inhibition zones were observed for compounds 2, 4 and 7. Compounds 1, 5 and 9 showed potent inhibition of human leukocyte elastase (HLE) with IC(50) values of 7.2, 13.3 and 10.9 μM, respectively.     

Fluorescent gallium and indium bis(thiosemicarbazonates) and their radiolabelled analogues: synthesis, structures and cellular confocal fluorescence imaging investigations

New fluorescent and biocompatible aromatic Ga(III)- and In(III)-bis(thiosemicarbazonato) complexes for dual mode optical and PET or SPECT molecular imaging have been synthesised via a synthetic method based on transmetallation reactions from Zn(II) precursors. Complexes have been fully characterised in the solid state by single crystal X-ray diffraction and in solution by spectroscopic methods (UV/Vis, fluorescence, (1)H and (13)C{(1)H} NMR). The bis(thiosemicarbazones) radiolabelled rapidly in high yields under mild conditions with (111)In (a gamma and Auger emitter for SPECT imaging and radiotherapy with t(1/2) = 2.8 d) and (68)Ga (a generator-available positron emitter for PET imaging with t(1/2) = 68 min). Cytotoxicity and biolocalisation studies using confocal fluorescence imaging and fluorescence lifetime imaging (FLIM) techniques have been used to study their in vitro activities and stabilities in HeLa and PC-3 cells to ascertain their suitability as synthetic scaffolds for future multimodality molecular imaging in cancer diagnosis and therapy. The observation that the indium complexes show certain nuclear uptake could be of relevance towards developing (111)In therapeutic agents based on Auger electron emission to induce DNA damage.     

A simple protocol for the comparative analysis of the structure and occurrence of biochemical pathways across superkingdoms

A biochemical pathway can be viewed as a series of chemical reactions occurring within a cell, each of which is carried out by one or more biological macromolecules (protein, RNA, or complexes thereof). Computational methods can be applied to assess whether one organism is able to perform a biochemical process of interest by checking whether its genome encodes all the components that are known to be necessary for the task. Here we present a simple strategy for collecting the above data that is based on, but not limited to, our experience on processes involving metal ions and metal-binding cofactors. The strategy is fully implemented in a bioinformatics package, Retrieval of Domains and Genome Browsing (RDGB), which is available from http://www.cerm.unifi.it/home/research/genomebrowsing.html . The use of RDGB allows users to perform all the operations that are needed to implement the aforementioned strategy with minimal intervention and to gather all results in an ordered manner, with a tabular summary. This minimizes the (bio)informatics needed, thus facilitating its use by nonexperts. As examples, we analyzed the pathways for the degradation of organic compounds containing one or two aromatic rings as well as the distribution of some proteins involved in Cu(A) assembly in more than a thousand prokaryotes.     

Liquid chromatography time-of-flight mass spectrometry following sorptive microextraction for the determination of fungicide residues in wine

This work evaluates the suitability of sorptive microextraction, using disposable silicone sorbents, and liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) for the determination of 15 fungicides in wine. Under optimized conditions, wine samples (10 mL) were diluted with the same volume of ultrapure water and poured in a glass vessel containing a magnetic stirrer and 4 g of sodium chloride. Extractions were performed at room temperature for 4 h, using an inexpensive silicone disk (12 μL volume) exposed directly to the sample. Thereafter, analytes were recovered with 0.2 mL of acetonitrile. The electrospray ionization (ESI) source was operated in the fast polarity switching mode obtaining, in the same injection, selective LC-MS records (extracted with a mass window of 10 ppm) of compounds rendering [M + H]⁺ and [M-H]⁻ ions. The method provided limits of quantification (LOQs) between 0.1 and 2.2 ng mL⁻¹, linear response ranges up to 500 ng mL⁻¹, relative recoveries from 75% to 117% and an inter-day variability below 15% for all analytes in red and white wine samples. The feasibility of in situ sample enrichment followed by delayed desorption and analysis is also assessed.     

Screening of fibrillogenesis inhibitors of β2-microglobulin: integrated strategies by mass spectrometry capillary electrophoresis and in silico simulations

The challenging search of ligands for the amyloidogenic protein β₂-microglobulin led us to set up an integrated strategy that combines analytical techniques and molecular modelling. Using a chemical library composed of 90 sulphonated molecules and a novel MS screening approach, we initially single out a few new binders. To check for anti-amyloid activity, the best hit obtained was thoroughly studied by docking analysis, affinity and refolding experiments by capillary electrophoresis and in vitro fibrillogenesis Thioflavin T test. Correlative analysis of the overall results obtained from the MS screening led to develop an equation able to identify the key factors of the affinity for β₂-microglobulin and to predict the affinity for novel derivatives. The proposed equation was then used for a virtual screening of a large compound database. Studies on the new hit thus retrieved confirm the predictive potential of both the equation on affinity and of docking analysis on anti-amyloid activity.     

Highly routinely reproducible alignment of H NMR spectral peaks of metabolites in huge sets of urines

A method to obtain high reproducibility of ¹H NMR chemical shift of peaks of biofluid metabolites, by simple acidification with HCl is evaluated. Biofluid ¹H NMR analysis is indeed spoiled by a strong chemical shift dependence of metabolite peaks on parameters such as ionic strength, concentration of some earth alkali cations and, mostly, on pH of samples. The resulting chemical shift variations, as large as 0.1 ppm, generate misalignments of homogeneous peaks, artifacts and misinterpretations.Reproducible alignment is essential in ¹H NMR based metabonomics, where peak misalignments prevent even very wide bins (i.e., 0.04 ppm, as elsewhere proposed) from being used to integrate spectral data for multivariate statistical analysis. Here is demonstrated that routine acidification with HCl to 1.2 ≤ pH ≤ 2.0 ensures highly reproducible peak alignment of urine ¹H NMR spectra. In this respect, simple inspection of citrate peaks in the urine can be used to measure pH, as it will be extensively discussed, in that at such low pH they show no dependency on other urine components as reported at higher pH. Under these conditions, in as many as 493 urine samples, in which concentrations of Ca²⁺, Mg²⁺, K⁺, Na⁺, Cl⁻, phosphate, and creatinine and ionic strength measured by means of well standardized conventional procedures, showed very wide ranges, peaks align within a SD always lower than 0.002 ppm, thus allowing the use of integration bins at least five times narrower than 0.04 ppm.     

Three weak solutions for elliptic Dirichlet problems

An existence result of three non-zero solutions for non-autonomous elliptic Dirichlet problems, under suitable assumptions on the nonlinear term, is presented. The approach is based on a recent three critical points theorem for differentiable functionals.     

Diorganotin-based coordination polymers derived from sulfonate/phosphonate/phosphonocarboxylate ligands

The reactions of diorganotin precursors [R(2)Sn(OR(1))(OSO(2)R(1))](n) [R = R(1) = Me (1); R = Me, R(1) = Et (2)] with an equimolar amount of t-butylphosphonic acid (RT, 8-10 h) in methanol result in the formation of identical products, of composition [(Me(2)Sn)(3)(O(3)PBu(t))(2)(O(2)P(OH)Bu(t))(2)](n) (3). On the other hand, a similar reaction of 2, when carried out in dichloromethane, affords [(Me(2)Sn)(3)(O(3)PBu(t))(2)(OSO(2)Et)(2)·MeOH](n) (4). A plausible mechanism implicating the role of solvent in the formation of these compounds has been put forward. In addition, the synthesis of [(Me(2)Sn)(3)(O(3)PCH(2)CH(2)COOMe)(2)(OSO(2)Me)(2)](n) (5) and [R(2)Sn(O(2)P(OH)CH(2)CH(2)COOMe)(OSO(2)R(1))](n) [R = Et, R(1) = Me (6); R = (n)Bu, R(1) = Et (7)] has been achieved by reacting 1 and related diorganotin(alkoxy)alkanesulfonates with 3-phosphonopropionic acid in methanol. The formation of a methylpropionate functionality on the phosphorus center in these structural frameworks results from in situ esterification of the carboxylic group. X-ray crystallographic studies of 1-7 are presented. The structures of 1 and 2 represent one-dimensional (1D) coordination polymers composed of alternate [Sn-O](2) and [Sn-O-S-O](2) cyclic rings formed by μ(2)-alkoxo and sulfonate ligands, respectively. For 3-5 and 7, variable bonding modes of phosphonate and/or sulfonate ligands afford the construction of two- and three-dimensional self-assemblies that are comprised of trinuclear tin entities with an Sn(3)P(2)O(6) core as well as [Sn-O-P-O](2) and/or [Sn-O-S-O](2) rings. The formation of a 1D coordination polymer in 6 is unique in terms of repeating eight-membered cyclic rings containing Sn, O, P, and S heteroatoms. The contribution from hydrogen-bonding interactions is also found to be significant in these structures.