Urinary levels of metal elements in the non-smoking general population in Italy: SIVR study 2012-2015.

The purpose of this study of the Italian Society of Reference Values (SIVR) was to provide the reference values for metals in the urine of the Italian general population. Thirteen sampling centres situated in the north, centre and south of Italy took part in this project. Each sampling centre selected 20 adult subjects.

Effect of ferric citrate on amyloid-beta peptides behavior.

Amyloid beta (Aβ) aggregation and oxidative stress are two of the central events in Alzheimer's Disease (AD). Both these phenomena can be caused by the interaction of Aβ with metal ions. In the last years the interaction between Zn , Cu , and Aβ was much studied, but between iron and Aβ it is still little known.

Methodology to define biological reference values in the environmental and occupational fields: the contribution of the Italian Society for Reference Values (SIVR).

Background: Biological reference values (RVs) explore the relationships between humans and their environment and habits. RVs are fundamental in the environmental field for assessing illnesses possibly associated with environmental pollution, and also in the occupational field, especially in the absence of established biological or environmental limits.

Objectives: The Italian Society for Reference Values (SIVR) determined to test criteria and procedures for the definition of RVs to be used in the environmental and occupational fields.

Iodine nutritional status and thyroid effects of exposure to ethylenebisdithiocarbamates.

Introduction: Italy is still characterized by a mild iodine deficiency and is among the most intensive users of chemical products for agriculture in Europe. The aim of this study was i) to evaluate thyroid effects of exposure to mancozeb, a fungicide widely used in agriculture, in a sample of Italian grapevine workers, and ii) to verify whether the iodine intake may modulate the risk of thyroid disruption due to the mancozeb metabolite ethylenthiourea (ETU).

Methods: One hundred seventy-seven occupationally exposed male workers (29 from Chianti, a mild iodine deficient area, and 148 from Bolzano an iodine sufficient province) and 74 non-occupationally exposed male controls (34 from Chianti and 40 from Bolzano) were enrolled in the study.

A critical concentration of N-terminal pyroglutamylated amyloid beta drives the misfolding of Ab1-42 into more toxic aggregates.

A wide consensus based on robust experimental evidence indicates pyroglutamylated amyloid-β isoform (AβpE3-42) as one of the most neurotoxic peptides involved in the onset of Alzheimer's disease. Furthermore, AβpE3-42 co-oligomerized with excess of Aβ1-42, produces oligomers and aggregates that are structurally distinct and far more cytotoxic than those made from Aβ1-42 alone. Here, we investigate quantitatively the influence of AβpE3-42 on biophysical properties and biological activity of Aβ1-42.

Electrostatic theory of the assembly of PAMAM dendrimers and DNA.

The electrostatic interactions mediated by counterions between a cationic PAMAM dendrimer, modelized as a sphere of radius and cationic surface charge highly increasing with generation, and a DNA, modelized as an anionic elastic line, are analytically calculated in the framework of condensation theory. Under these interactions the DNA is wrapped around the sphere. For excess phosphates relative to dendrimer primary amines, the free energy of the DNA-dendrimer complex displays an absolute minimum when the complex is weakly negatively overcharged.

Lamellar cationic lipid-DNA complexes from lipids with a strong preference for planar geometry: A Minimal Electrostatic Model.

We formulate and analyze a minimal model, based on condensation theory, of the lamellar cationic lipid (CL)-DNA complex of alternately charged lipid bilayers and DNA monolayers in a salt solution. Each lipid bilayer, composed by a random mixture of cationic and neutral lipids, is assumed to be a rigid uniformly charged plane. Each DNA monolayer, located between two lipid bilayers, is formed by the same number of parallel DNAs with a uniform separation distance.

[Benzene in soft drinks: a study in Florence (Italy)].

The aim of this study was to determine the amount of benzene present in soft drinks sold in Florence (Italy). We analyzed 28 different types of soft drinks, by measuring concentrations of benzoic acid, sorbic acid, ascorbic acid (using high performance liquid chromatography with UV detection) and benzene (using gas chromatography and mass spectrometry). Data was analysed by using SPSS 18.

Differential toxicity, conformation and morphology of typical initial aggregation states of Aβ1-42 and Aβpy3-42 beta-amyloids.

Among the different species of water-soluble β-peptides (Aβ1-42, Aβ1-40 and N-terminal truncated Aβ-peptides), Aβpy3-42 is thought to play a relevant role in Alzheimer's pathogenesis due to its abundance, resistance to proteolysis, fast aggregation kinetics, dynamic structure and high neurotoxicity. To evaluate the specific structural characteristics and neurotoxicity of Aβpy3-42, we separated different aggregation states of Aβ1-42 and Aβpy3-42 using fast protein liquid chromatography, isolating in both cases three peaks that corresponded to sa (small), ma (medium) and la (large) aggregates. Conformational analysis, by circular dichroism showed a prevailing random coil conformation for sa and ma, and typical β-sheet conformation for la.

[Biogenic amines in epigeal spontaneous mushrooms: indicators of quality and freshness?].

Purpose of the present study is to determine the qualitative and quantitative composition of nine biogenic amines (BA) in 153 samples of epigeal spontaneous mushrooms (Boletus edulis and Amanita Caesarea), sampled at large and small food retail shops in the Florence area. Each BA has been identified and quantified using a liquid chromatography system with a reversed phase, C18 column and post-column derivatization with o-oftalaldeide. The results have shown a widespread presence of each amine, although with varying frequency and concentration, and an increasing concentration of tyramine and putrescine in samples with poor organoleptic quality than those in good conditions.

Clusters in strong polyelectrolyte solutions in the condensation theory approach.

The interaction free energy of parallel clusters of like-charged rod polyelectrolytes in solution is calculated in the framework of the extended condensation theory. For sufficiently high linear charge density of the polyelectrolyte, clustering takes place. The greater is the number of polyelectrolytes participating to the cluster, the smaller is the equilibrium interpolyelectrolyte distance, and the deeper is the corresponding free energy minimum.

Wrapped-around models for the lac operon complex.

The protein-DNA complex, involved in the lac operon of enteric bacteria, is paradigmatic in understanding the extent of DNA bending and plasticity due to interactions with protein assemblies acting as DNA regulators. For the lac operon, two classes of structures have been proposed: 1), with the protein tetramer lying away from the DNA loop (wrapped-away model); and 2), with the protein tetramer lying inside the DNA loop (wrapped-around model). A recently developed electrostatic analytical model shows that the size and net charge of the Lac protein tetramer allow the bending of DNA, which is consistent with another wrapped-around model from the literature.

N-terminal truncated pyroglutamyl beta amyloid peptide Abetapy3-42 shows a faster aggregation kinetics than the full-length Abeta1-42.

We tested directly the differences in the aggregation kinetics of three important beta amyloid peptides, the full-length Abeta1-42, and the two N-terminal truncated and pyroglutamil modified Abetapy3-42 and Abetapy11-42 found in different relative concentrations in the brains in normal aging and in Alzheimer disease. By following the circular dichroism signal and the ThT fluorescence of the solution in phosphate buffer, we found substantially faster aggregation kinetics for Abetapy3-42. This behavior is due to the particular sequence of this peptide, which is also responsible for the specific oligomeric aggregation states, found by TEM, during the fibrillization process, which are very different from those of Abeta1-42, more prone to fibril formation.

The supramolecular association of polyelectrolytes to complementary charged surfactants and protein assemblies.

Cohesion matters! The correlation between the conformational rigidity of the polyelectrolyte and the size and stability of the globular assembly is discussed in this review article. Some examples of models for the association of polyelectrolytes to globular assemblies are shown here.Supramolecular complexes of strong polyelectrolytes and oppositely charged ionic micelles or protein assemblies derive their main stabilization from electrostatic interactions that include the counterion condensation/release mechanism and from hydrophobic interactions distributed along apolar sections of the components.

Attraction between like-charged polyelectrolytes in the extended condensation theory.

The interaction free energy of like-charged polyelectrolytes in solution is calculated in the framework of the extended counterion condensation theory, recently given by Schurr and Fujimoto, Biophys. Chem. 2002, 101-102, 425-445.

Assessment of foetal exposure to cigarette smoke after recent implementations of smoke-free policy in Italy.

Aim: We investigated foetal exposure to cigarette smoke following maternal active and passive smoking at the end of the pregnancy in a cohort of mother-infant dyads after recent implementation of the Italian smoke-free legislation and information campaigns against smoking.

Methods: Study subjects were 979 mothers and their newborns attended at one of the major Florence hospitals between the end of 2004 and during 2005, when smoking banning legislation in all the enclosed places of employment was completely enforced. A structured questionnaire was completed by mothers and cord serum cotinine was used as a biomarker of foetal exposure to maternal smoke at the end of the pregnancy.

Reference values of urinary trans,trans-muconic acid: Italian Multicentric Study.

This article reports the results of a study, conducted in the framework of the scientific activities of the Italian Society for Reference Values, aimed at defining reference values of urinary trans,trans-muconic acid (t,t-MA) in the general population not occupationally exposed to benzene. t,t-MA concentrations detected in 376 subjects of the resident population in three areas of Italy, two in central (Florence and southern Tuscany) and one in northern Italy (Padua), by three laboratories, compared by repeated interlaboratory controls, showed an interval of 14.4-225.

Intracellular accumulation of a mild-denatured monomer of the human PrP fragment 90-231, as possible mechanism of its neurotoxic effects.

Because of high tendency of the prion protein (PrP) to aggregate, the exact PrP isoform responsible for prion diseases as well as the pathological mechanism that it activates remains still controversial. In this study, we show that a pre-fibrillar, monomeric or small oligomeric conformation of the human PrP fragment 90-231 (hPrP90-231), rather than soluble or fibrillar large aggregates, represents the neurotoxic species. In particular, we demonstrate that monomeric mild-denatured hPrP90-231 (incubated for 1 h at 53 degrees C) induces SH-SY5Y neuroblastoma cell death, while, when structured in large aggregates, it is ineffective.

Most sensitive urinary cotinine cut-off level for environmental tobacco smoke exposure assessment: a pilot study.

The aim of this pilot study was to determine the most sensitive urinary cotinine level able to assess environmental tobacco smoke (ETS) exposure. 54 Florentine subjects (29 males and 25 females), reporting to be nonsmokers and exposed (E) or not exposed (NE) to ETS at home, at work or in places of recreation, were examined. The urinary cotinine concentration was determined using gaschromatographic analysis in samples collected on three consecutive days.

Generalized electrostatic model of the wrapping of DNA around oppositely charged proteins.

Histonelike proteins in prokaryotes and histone octamers in eukaryotes carry large positive charges, which are responsible of strong electrostatic interactions with DNA. As a result, DNA wraps around proteins and genetic information is condensed. We describe a generalized model of these electrostatic interactions mediated by salt that explains the wrapping of DNA around the nucleosome octamer, around remodeling factors in eukaryotes and around histonelike proteins in prokaryotes.

Modeling H3 histone N-terminal tail and linker DNA interactions.

Molecular dynamics computer simulations were performed for the 25-residue N-terminal tail of the H3 histone protein in the proximity of a DNA segment of 10 base pairs (bp), representing a model for the linker DNA in chromatin. Several least biased configurations were used as initial configurations. The secondary structure content of the protein was increased by the presence of DNA close to it, but the locations of the secondary motifs were different for different initial orientations of the DNA grooves with respect to the protein.

Electrostatic interactions with histone tails may bend linker DNA in chromatin.

Is linker DNA bent in the 30-nm chromatin fiber at physiological conditions? We show here that electrostatic interactions between linker DNA and histone tails including salt condensation and release may bend linker DNA, thus affecting the higher order organization of chromatin.

Hyaluronan chain conformation and dynamics.

An overview of the present state of research in the field of hyaluronan chain conformational aspects is presented. The relationship between structure and dynamics are illustrated for a series of hyaluronan oligomers. Conformational characteristics of hyaluronan chains are discussed, together with the dynamic chain patterns, evaluated by using a theoretical approach to diffusive polymer dynamics.

Designing generalized statistical ensembles for numerical simulations of biopolymers.

Conformational properties of polymers, such as average dihedral angles or molecular alpha-helicity, display a rather weak dependence on the detailed arrangement of the elementary constituents (atoms). We propose a computer simulation method to explore the polymer phase space using a variant of the standard multicanonical method, in which the density of states associated to suitably chosen configurational variables is considered in place of the standard energy density of states. This configurational density of states is used in the Metropolis acceptance/rejection test when configurations are generated with the help of a hybrid Monte Carlo algorithm.

Determination of N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine by high-performance liquid chromatography combined with mass spectrometry.

A simple, sensitive and specific method for the quantification of N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urines of the general population and of exposed workers has been developed. Samples were first diluted with phosphate buffer followed by purification by solid-phase extraction (SPE) with SAX columns prior to analysis by liquid chromatography/mass spectrometry (LC/MS). An external standard was used for the quantification together with selected ion monitoring of m/z 219, [M-H]-.