Predicting estrogen receptor binding of chemicals using a suite of in silico methods - Complementary approaches of (Q)SAR, molecular docking and molecular dynamics.

With the aim of obtaining reliable estimates of Estrogen Receptor (ER) binding for diverse classes of compounds, a weight of evidence approach using estimates from a suite of in silico models was assessed. The predictivity of a simple Majority Consensus of (Q)SAR models was assessed using a test set of compounds with experimental Relative Binding Affinity (RBA) data. Molecular docking was also carried out and the binding energies of these compounds to the ERα receptor were determined. For a few selected compounds, including a known full agonist and antagonist, the intrinsic activity was determined using low-mode molecular dynamics methods. Individual (Q)SAR model predictivity varied, as expected, with some models showing high sensitivity, others higher specificity. However, the Majority Consensus (Q)SAR prediction showed a high accuracy and reasonably balanced sensitivity and specificity. Molecular docking provided quantitative information on strength of binding to the ERα receptor. For the 50 highest binding affinity compounds with positive RBA experimental values, just 5 of them were predicted to be non-binders by the Majority QSAR Consensus. Furthermore, agonist-specific assay experimental values for these 5 compounds were negative, which indicates that they may be ER antagonists. We also showed different scenarios of combining (Q)SAR results with Molecular docking classification of ER binding based on cut-off values of binding energies, providing a rational combined strategy to maximize terms of toxicological interest.

Identification of Metabolites of the Fungicide Penconazole in Human Urine.

Penconazole (PEN) is a fungicide used in agriculture that has been classified as hazardous to humans and the environment. The objective of this work was to identify PEN urinary metabolites in humans and propose a biomarker for PEN exposure. Five urine samples were collected from agricultural workers who worked with and were exposed to PEN. Samples were analyzed by liquid chromatography coupled with hybrid triple quadrupole-linear ion trap mass spectrometry, with the source operating in the electrospray ionization mode. Metabolites previously identified in animal studies were searched as possible metabolites in humans. Candidate metabolites were first identified by multiple reaction monitoring following the protonated molecular ions that generated the protonated triazole moiety, which is expected to be present in all PEN metabolites; second, the isotopic patterns of the molecular ions were checked for consistency with the presence of two chlorine atoms; third, the full mass spectra were evaluated for consistency with the molecular structure. Seven different oxidized metabolites were found, both in the free and glucuronide conjugate forms. The major metabolite was the monohydroxyl-derivative PEN-OH (median molar fraction approximately 0.92 as a sum of free and glucuronide conjugated form). The product of further oxidation was the carboxyl-derivate PEN-COOH (median molar fraction approximately 0.03). After hydrolysis with ß-glucuronidase, the free compounds were quantified in the presence of deuterated PEN as an internal standard; PEN-OH levels ranged from 230 to 460 µg/L, and PEN-COOH levels ranged from 5.2 to 16.7 µg/L. We propose a pathway for PEN metabolism in humans and suggest PEN-OH, after hydrolysis of glucuronide conjugates, as a biomarker for monitoring human exposure to PEN.

A peptide topological template for the dispersion of [60]fullerene in water.

Solubilization of [60]fullerene in water is a major challenge for biological and medical applications. To this purpose in this communication we describe for the first time a new dispersing system based on a peptide topological template. The presence of two carbobenzyloxy groups on the peptide side chains allows π-π interactions with [60]fullerene leading to the formation of stable supramolecular nanocomposites by means of mechanochemical methods. In particular, by high speed vibration milling colloidal dispersions (mean particle diameter 63 nm) containing up to 1.3 mg mL(-1) of [60]fullerene were obtained. Its presence in water was verified through UV-Vis and MALDI-TOF measurements, while its concentration was determined by thermogravimetric analysis.

Identification and quantification of metabolites of the fungicide tebuconazole in human urine.

Tebuconazole (TEB) is a fungicide used in agriculture; the objective of this work was to identify and quantify TEB metabolites in human urine. Samples from seven vineyard workers exposed to TEB were submitted to liquid chromatography interfaced with a triple quadrupole mass spectrometer, equipped with an electron spray source, and a linear ion trap to gain a profile of candidate metabolites. Based on the presence of the ion m/z 70 in the MS/MS spectra, which corresponds to protonated triazole (a specific moiety of TEB), and the isotopic pattern of the molecular ions, typical of molecules with one chlorine atom, hydroxyl and carboxyl derivatives of TEB, that is, TEB-OH and TEB-COOH, were identified as major metabolites, both as free molecules and as glucuronide (Glc) conjugates. The mean molar fractions were 0.67, 0.13, 0.13, and 0.07 for TEB-O-Glc, TEB-OH, TEB-COO-Glc, and TEB-COOH. Urine samples were submitted to hydrolysis with ß-glucuronidase, and the free compounds were quantified in the presence of deuterated TEB (TEB-d6) as the internal standard (IS), by multiple reaction monitoring (MRM) mode. The assay was linear in the ranges of 0.2-600 µg/L and 0.1-240 µg/L for TEB-OH and TEB-COOH, respectively; precision, accuracy, and the limit of quantification (LOQ) were <3.1%, 98-103%, and 0.3 µg/L for both analytes. An evaluation of matrix effects showed that the use of TEB-d6 controlled these sources of bias. The urinary levels of TEB-OH and TEB-COOH in specimens collected from farmers exposed to TEB ranged from 10 to 473 and from 3 to 159 µg/L, respectively.

Synthesis of luminescent 3D microstructures formed by carbon quantum dots and their self-assembly properties.

We report in this communication the synthesis of star-shaped carbon quantum dots-(poly-γ-benzyl-L-glutamate) conjugates that self-assemble into microstructures and retain the characteristic emission properties of the native dots. Dots were used either as an initiator to give a daisy-like peptide-polymer structure or as capping agents towards more elaborated hybrid nanostructures.

Bulky toroidal and vesicular self-assembled nanostructures from fullerene end-capped rod-like polymers.

In this work, we present novel fullerene (C60) end-capped rod-like polypeptide-polymers, obtained by one-pot thiol-ene chemistry. These systems are able to self-assemble in water creating precise bulky microstructures of toroidal or vesicular shapes. Independent molecular dynamics simulations supported the observed experimental results.

Expression of gastrin-releasing peptide receptor in patients with cutaneous malignant melanoma.

BACKGROUND: Gastrin-releasing peptide (GRP) is a neuroendocrine peptide shown to possess growth-stimulatory effects in many types of human cancers. High levels of GRP receptors have been found in various types of human cancers, and preclinical studies exploring the therapeutic use of GRP receptor (GRPR) antagonists have been reported, with promising results. Data on GRPR expression in human malignant melanoma (MM) are scanty. AIM: To determine GRPR expression in biopsy material obtained from patients diagnosed with cutaneous MM. METHODS: Immunohistochemistry was performed on formalin-fixed, paraffin wax-embedded tissue samples obtained from 51 patients with cutaneous MM. The relationship between GRPR expression and the clinicopathological features was analysed using the Fisher exact test. RESULTS: GRPR immunoexpression was found in 42/51 cutaneous melanoma samples (82.4%). It was strongly expressed in 30 cases (58.9%). There was no significant difference in the levels of GRPR expression between primary or metastatic lesions. We correlated the GRPR expression score with pathological features associated with prognosis in cutaneous MM. There was no significant difference in GRPR expression in relation to Clark level (CL; P = 0.35) or Breslow Index (BI; P = 0.17). CONCLUSIONS: GRPR expression levels were high in tissue specimens of MM (82.4%), but did not correlate with pathological features related to prognosis, such as CL or BI. Further studies, preferably in a larger patient population, are warranted.

Pesticide induced immunotoxicity in humans: a comprehensive review of the existing evidence.

The immune system can be the target of many chemicals, with potentially severe adverse effects on the host's health. In Western countries pesticides, together with new and modified patterns of exposure to chemicals, have been implicated in the increasing prevalence of diseases associated with alterations of the immune response, such as hypersensitivity reactions, certain autoimmune diseases and cancers. Xenobiotics may initiate, facilitate or exacerbate pathological immune processes, resulting in immunotoxicity by induction of mutations in genes coding for immunoregulatory factors, modifying immune tolerance and activation pathways. The purpose of this article is to update the evidence of pesticide immunotoxicity. Even if experimental data as well as sporadic human studies indicate that some pesticides can affect the immune system, overall, existing epidemiological studies are inadequate to raise conclusions on the immunotoxic risk associated to pesticide exposure. The available studies on the effects of pesticides on human immune system have several limitations including poor indication on exposure levels, multiple chemical exposures, heterogeneity of the approach, and difficulty in giving a prognostic significance to the slight changes often observed. Further studies are necessary, and they should be preferably carried out through comparison of pre and post-exposure findings in the same group of subjects with a matched control group. Attempt should be made to define the prognostic significance of slight changes often observed. Animal and in vitro studies are also important and necessary to scientifically support epidemiological evidences on pesticide-induced immunotoxicity.

[Time course of excretion of tebuconazole and its metabolites in vineyard workers]. / Cinetica di escrezione del tebuconazolo e dei suoi metaboliti in viticoltori.

Tebuconazole (TEB) is a fungicide widely used in vineyards. This work aimed at the identification of urinary metabolites of TEB for the biological monitoring of exposure, and to study their kinetics of excretion. Major urinary metabolites of TEB in rats are t-butyl-hydroxy-and-carboxy-tebuconazole (TEB-OH and TEB-COOH). TEB and these metabolites were determined in urine samples of 5 wine growers who collected each void before (24 hours), during and after (48 hours) TEB application. These chemicals were found in 95%, 100% and 100% of the samples with levels of < 1.5-13.4 microg/L for TEB, 5.2-749 microg/L for TEB-OH e 2.8-234 microg/l for TEB-COOH. TEB-OH is the major metabolite of TEB, its concentration increases at the end of exposure and peaks after 16-24 hours. TEB-COOH has similar pattern. TEB-OH and TEB -COOH are promising candidates for biological monitoring of TEB exposure; preliminary results suggest the day after the application as the best sampling time.

Biochemical and toxicological evidence of neurological effects of pesticides: the example of Parkinson's disease.

Parkinson's disease (PD) is frequently reported to be associated with pesticide exposure but the issue has not yet been solved because the data are inconsistent and the studies suffer from several biases and limitations. The aim of this article is to summarise available biochemical and toxicological data on some pesticides, particularly on paraquat, that might help in the evaluation of epidemiological data. The nigrostriatal system appears to be particularly sensitive to oxidative damage caused by different mechanisms and agents, thus supporting the epidemiological evidence that Parkinson's disease is in fact an environmental disease. In available experimental studies, animals have been treated with a high single or a few doses of pesticide, and have been followed up for a few days or weeks after treatment. Moreover, experimental data indicate additive/synergistic effects of different pesticides that act on different targets within the dopaminergic system. In these conditions and to a different extent, pesticides such as paraquat, maneb and other dithiocarbamates, pyrethroids, rotenone, and dieldrin cause neurotoxic effects that may suggest a possible role in the development of a PD-like syndrome in animals. Although, all the characteristics of PD cannot be reproduced by any single chemical, these data can be of help for understanding the role of pesticide exposure in human PD development. On the other hand farmers are exposed for days or weeks during several years to much lower doses than those used in experimental studies. Therefore, a firm conclusion on the role of pesticide exposure on the increased risk of developing PD cannot be drawn. However, it is suggested that close follow up of survivors of acute poisonings by these pesticides, or identification in epidemiological studies of such subjects or of those reporting episodes of accidentally high exposure will certainly provide information useful for the understanding of the relevance of actual human exposure to these pesticides in the development of PD. Also exposure to multiple pesticides, not necessarily at the same time, should be evaluated in epidemiological studies, as suggested by the additive/synergistic effects observed in experimental studies.

[Evaluation of experimental data for developmental neurotoxicity of pesticides]. / Valutazione dei dati sperimentali per la neurotossicità dello sviluppo dei pesticidi.

Epidemiological studies on neurodevelopmental effects of pesticides are inconclusive. Experimental developmental neurotoxicity studies, sometimes show effects on pups given doses lower than adults; most of the times these effects were transient, aspecific, with scattered biochemical, molecular or neurobehavioural changes, generally associated with high bolus doses. At repeated low doses, effects in pups did not occur at doses lower than in adults. Since the effects of high bolus doses are possible, preventive interventions should aim at reducing these exposures.

[Risk assessment and risk management of chemical exposures in agriculture]. / Valutazione e gestione del rischio chimico in agricoltura.

The most important risk in agriculture derives from exposure to pesticides. Pesticide risk assessment is conducted before (pre-market) and after (post-market) the introduction in use of the substance. Evaluation of the extensive toxicological studies required for all pesticides leads to the definition of the Acceptable Operator Exposure Level (AOEL) expressed as systemic dose (mg/kg). The AOEL is compared with exposures estimated by exposure models, that are currently being revised in the European Union. Only if estimated exposure is below the AOEL the product is authorised, sometimes with compulsory use of certain personal protective equipment. These are reported in the label. Post-marketing activities include health surveillance, biological monitoring, exposure monitoring, enforcement on the use of proper and properly maintained equipment, and use of proper personal protection devices.

Neurobehavioural effects of pesticides with special focus on organophosphorus compounds: which is the real size of the problem?

The risk of neurobehavioural impairment as a consequence of a prolonged, low dose exposure to neurotoxic pesticides is not clearly demonstrated despite numerous publications addressing the topic. We reviewed the 24 papers published on human neurobehavioural effects of organophosphorus and/or carbamates pesticides up to May 1st 2008. Variables evaluated were compound/s addressed, number of subjects, approach to measure or estimate exposure, characteristics of control groups and presence of confounders, methodological approach, and type of alteration, taking into account cognitive, sensory-motor, psychological, and psychomotor measures. A total of 6 papers considered the whole spectrum of functions, the studies yielding positive or uncertain results were 13 (68%) for cognitive function, 11 (69%) for psychomotor function, 11 (65%) for sensory-motor function, and 11 (65%) for psychological function impairment. In 46% of the positive studies a previous severe acute poisoning was reported. Exposure levels were measured only in 5 studies, and very often there were problems in the selection of controls, and firm conclusions on the risk of neurobehavioural effects cannot be reached yet. The main limits of the available data are: limited number of studies and compounds addressed, significant differences in the approach among studies, poor concordance of the results of different studies, and difficulties in controlling confounding factors. Nevertheless, there are sufficient data to conclude that neurobehavioural impairment might be the consequence of an acute poisoning, and possibly the consequence of relatively high and prolonged exposures.

The search of the target of promotion: Phenylbenzoate esterase activities in hen peripheral nerve.

Certain esterase inhibitors, such as carbamates, phosphinates and sulfonyl halides, do not cause neuropathy as some organophosphates, but they may exacerbate chemical or traumatic insults to axons. This phenomenon is called promotion of axonopathies. Given the biochemical and toxicological characteristics of these compounds, the hypothesis was made that the target of promotion is a phenyl valerate (PV) esterase similar to neuropathy target esterase (NTE), the target of organophosphate induced delayed polyneuropathy. However, attempts to identify a PV esterase in hen peripheral nerve have been, so far, unsuccessful. We tested several esters, other than PV, as substrates of esterases from crude homogenate of the hen peripheral nerve. The ideal substrate should be poorly hydrolysed by NTE but extensively by enzyme(s) that are insensitive to non-promoters, such as mipafox, and sensitive to promoters, such as phenyl methane sulfonyl fluoride (PMSF). When phenyl benzoate (PB) was used as substrate, about 65% of total activity was resistant to the non-promoter mipafox (up to 0.5 mM, 20 min, pH 8.0), that inhibits NTE and other esterases. More than 90% of this resistant activity was sensitive to the classical promoter PMSF (1 mM, 20 min, pH 8.0) with an IC(50) of about 0.08 mM (20 min, pH 8.0). On the contrary, the non-promoter p-toluene sulfonyl fluoride caused only about 10% inhibition at 0.5 mM. Several esterase inhibitors including, paraoxon, phenyl benzyl carbamate, di-n-butyl dichlorovinyl phosphate and di-isopropyl fluorophosphate, were tested both in vitro and in vivo for inhibition of this PB activity. Mipafox-resistant PMSF-sensitive PB esterase activity(ies) was inhibited by promoters but not by non promoters and neuropathic compounds.

[Evaluation and management of pesticide risk in agriculture: the experience of the Region of Lombardy (Italy)]. / Valutazione e gestione del rischio da antiparassitari in agricoltura: l'esperienza della Regione Lombardia.

The evaluation of chemical risk in agriculture is complicated because of difficulties in obtaining measures representative of working conditions. This is the reason why experiences finalized at producing risk estimates are running. In this frame, a Regional working group has developed the project "Pesticide exposure and risk profiles in agriculture". Priority scenarios have been selected and the main variables correlated with pesticide exposure have been pointed out. A value for each variable has been defined. The sum of these values allows the definition of "Exposure Indices" (EI), which can be reduced by multiplication for a coefficient calculated based on use of personal protective devices, training and education and equipment conditions. A Risk Index is calculated as the product of EI per a toxicity index, calculated based on the risk phrases of the substances used ("Risk Profile"). Risk Profiles allow the production of risk estimates and the definition of the appropriate preventive interventions. Next phase will be addressed at the validation of the model, to be carried out through the determination of the levels of concordance between the risk class allocation obtained from the model and the one obtained from environmental and biological measures, in the same groups of workers.

[Implementation of a safety and health planning system in a teaching hospital]. / Implementazione di un sistema di gestione per la salute e la sicurezza (SGSS) in un'Azienda Ospedaliera Polo Universitario.

University Hospital "L. Sacco" had started in 2006 a two-year project in order to set up a "Health and Safety Management System (HSMS)" referring to the technical guideline OHSAS 18001:1999 and the UNI and INAIL "Guidelines for a health and safety management system at workplace". So far, the following operations had been implemented: Setting up of a specific Commission within the Risk Management Committee; Identification and appointment of Departmental Representatives of HSMS; Carrying out of a training course addressed to Workers Representatives for Safety and Departmental Representatives of HSMS; Development of an Integrated Informative System for Prevention and Safety; Auditors qualification; Inspection of the Occupational Health Unit and the Prevention and Safety Service: reporting of critical situations and monitoring solutions adopted. Short term objectives are: Self-evaluation through check-lists of each department; Sharing of the Improvement Plan among the departments of the hospital; Planning of Health and Safety training activities in the framework of the Hospital Training Plan; Safety audit.

Bicyclic and tricyclic thiophenes as protein tyrosine phosphatase 1B inhibitors.

A novel pyridothiophene inhibitor of PTP1B was discovered by rational screening of phosphotyrosine mimics at high micromolar concentrations. The potency of this lead compound has been improved significantly by medicinal chemistry guided by X-ray crystallography and molecular modeling. Excellent consistency has been observed between structure-activity relationships and structural information from PTP1B-inhibitor complexes.

A topographically and conformationally constrained, spin-labeled, alpha-amino acid: crystallographic characterization in peptides.

2,2,6,6-Tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) is a topographically and conformationally restricted, nitroxide containing, C(alpha)-tetrasubstituted alpha-amino acid. Here, we describe the molecular and crystal structures, as determined by X-ray diffraction analyses, of a TOAC terminally protected derivative, the cyclic dipeptide c(TOAC)(2).1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) solvate, and five TOAC-containing, terminally protected, linear peptides ranging in length from tetra- to hepta-peptides. Incipient and fully developed, regular or distorted 3(10)-helical structures are formed by the linear peptides. A detailed discussion on the average geometry and preferred conformation for the TOAC piperidine ring is also reported. The X-ray diffraction structure of an intramolecularly cyclized side product resulting from a C-activated TOAC residue has also been determined.

On the orange color of Z-Trp-ONPo.

Out of all nitrophenyl esters of N(alpha)-protected alpha-amino acids Z-Trp-ONP(o) is the only one which is deep orange colored in the crystalline state. Any change in N(alpha)-protection, nature of amino acid, spatial separation between Trp and the ester-group or position of the nitro-substitutent in the aromatic ring of the ester function results in a loss of this characteristic property. We solved the molecular and crystal structure of Z-l-Trp-ONP(o) by X-ray diffraction analysis and investigated its color changes and visible (vis) and infrared (IR) absorption spectra in the solid state as a function of the amino acid derivative/KBr (w/w) ratio in the pellets. This investigation was extended to toluene solutions of different Z-Trp-ONP(o) concentrations by use of vis absorption and proton magnetic resonance spectroscopic techniques. The onset of the orange color correlates closely with the appearance of a concentration-dependent absorption band near 500 nm and concentration-dependent shifts of the urethane and indole NH proton resonances. Our observations can be explained by the formation of an intermolecular charge transfer complex involving the Trp indole and the -ONP(o) nitrophenyl as the donor and the acceptor moieties, respectively.