Low-dose benzene exposure monitoring of oil refinery workers: inhalation and biomarkers

Airborne benzene in workplaces has progressively decreased due to preventive actions and the redesigning of facility processes. Professionals who assess occupational exposure should select techniques to detect benzene levels comparable to ambient air exposure. Thus, sensitive biomarkers are needed to discriminate the effects of confounding factors, such as smoking or sorbic acid (SA). In order to identify sensitive biomarkers and to study their correlation with confounding factors, 23 oil refinery workers were enrolled in the study; their airborne benzene exposures and biomarkers were monitored. Urinary benzene (U-B), t,t-muconic acid (t,t-MA), and S-phenylmercapturic acid (SPMA) were quantified. Urinary cotinine (U-C) and t,t-sorbic acid (t,t-SA) were evaluated to flag smoking and SA intake, respectively. The benzene measured in personal inhalation sampling ranged from 0.6 to 83.5 (median 1.7) µg/m3. The concentration range of the biomarkers, U-B, t,t-MA, and SPMA, were 18–4893 ng/m3, <10–79.4 µg/g creatinine, and <0.5–3.96 µg/g creatinine, respectively. Pearson tests were carried out; the best correlations were between airborne benzene and U-B (µg/L r = 0.820, p < 0.001) and between benzene and SPMA (g/L r = 0.812, p < 0.001), followed by benzene and t,t-MA (mg/L r = 0.465, p = 0.039). From our study, U-B and SPMA result to be the most reliable biomarkers to assess the internal number of low doses of benzene exposure, thanks to their specificity and sensitivity

Peptoid Residues and beta-Turn Formation

We synthesized and tested for intramolecularly H-bonded beta-turn formation a set of terminally protected tripeptoids containing in position i+1/i+2 either a residue of N-methylglycine or of N-isobutylglycine. By exploiting FT-IR absorption and 1H NMR techniques we compared their folding tendencies with those of a variety of reference peptides. The amount of beta-turn induction and the relative extent of the various types of intramolecularly H-bonded beta-turn conformers were determined in chloroform solution

Peptoid Residues and beta-Turn Formation

We synthesized and tested for intramolecularly H-bonded beta-turn formation a set of terminally protected tripeptoids containing in position i+1/i+2 either a residue of N-methylglycine or of N-isobutylglycine. By exploiting FT-IR absorption and 1H NMR techniques we compared their folding tendencies with those of a variety of reference peptides. The amount of beta-turn induction and the relative extent of the various types of intramolecularly H-bonded beta-turn conformers were determined in chloroform solution

Combining Radon Deficit, NAPL Concentration, and Groundwater Table Dynamics to Assess Soil and Groundwater Contamination by NAPLs and Related Attenuation Processes

Soil and groundwater contamination by NAPLs (Non-Aqueous Phase Liquids) is certainly a big issue for protecting the environment. In situ clean-up actions are routinely applied to mitigate the risk and are supplemented by monitoring surveys to assess the degree, extension, and evolution of the contamination. Radon gas is here used as a tracer of contamination because of its high solubility in non-polar solvents that produce a reduced concentration of the gas in polluted soil and groundwater with reference to radon levels in adjacent “clean” areas. This approach was employed in two sites where gasoline and diesel spillage occurred, causing soil and groundwater contamination. The two case studies were chosen because of their difference in terms of the hydrogeological features, age of the spillage, composition of residual NAPLs, and clean-up measures to test the advantages and limits of this approach in a variety of settings. Radon data, NAPL concentration in the groundwater (mainly total hydrocarbons, Methyl Tertiary-Butyl Ether and Ethyl Tertiary-Butyl Ether) and the depth of the groundwater table were periodically collected in surveys that spanned a period of two years. This dataset was statistically processed using principal component analysis to unravel which factors and attenuation processes are working in the sites and the response of the radon deficit approach to this complex series of phenomena concurrently occurring there

First Direct Observation of C=O\ub7\ub7\ub7H-N Intramolecular Hydrogen Bonds in 3-10-Helical Peptides.

Differentiating helices: The direct observation of hydrogen bonds by 3hJN,C\u2032 scalar couplings (see picture) is not only possible for alpha-helix and \u3b2-sheet peptides and proteins, but for 310-helical peptides as well. The method also provides information on terminal fraying of helices and allows the discrimination between alpha and 310 helices

Concomitant occurrence of peptide 3(10)- and alpha-helices probed by NMR

Oligopeptides based on protein (C\u3b1-trisubstituted) \u3b1-amino acids are known to undergo \u3b1-helix to unordered conformation transitions under appropriate experimental conditions. On the other hand, oligopeptides rich in C\u3b1-tetrasubstituted \u3b1-amino acids present a rather peculiar stereochemistry due to significant constraints imposed on their conformational freedom by these residues. Specifically, most of the C\u3b1-tetrasubstituted \u3b1-amino acids have been extensively documented to possess a very high intrinsic helix-forming capacity. The narrow conformational space accessible includes both the classical \u3b1-helix and the 310-helix. It was shown that among the C\u3b1-tetrasubstituted chiral \u3b1-amino acids the \u3b2-branched C\u3b1-methyl-L-valine [L-(\u3b1Me)Val] is the residue with the most pronounced bias toward the right-handed 310-helix. Strong initial experimental evidence has indicated that the terminally blocked 12[L-(\u3b1Me)Val]8 12 sequence adopts a fully developed, right-handed 310-helical conformation both in the crystal state and in structure-supporting solvents. More recently, the interesting property of this peptide to fold in solution both in the 310- and in the \u3b1-helix has emerged. The type of helical conformation adopted was found to depend on experimental conditions, as clearly shown by vibrational and electronic CD techniques. Under appropriate conditions, the conformational transition from 310- to \u3b1-helix is very slow (the time scale is on the order of several days)

Discovering miRNA regulatory networks in holt-oram syndrome using a zebrafish model

MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in the post-transcriptional regulation of gene expression. miRNAs are involved in the regulation of many biological processes such as differentiation, apoptosis, and cell proliferation. miRNAs are expressed in embryonic, postnatal, and adult hearts, and they have a key role in the regulation of gene expression during cardiovascular development and disease. Aberrant expression of miRNAs is associated with abnormal cardiac cell differentiation and dysfunction. Tbx5 is a member of the T-box gene family, which acts as transcription factor involved in the vertebrate heart development. Alteration of Tbx5 level affects the expression of hundreds of genes. Haploinsufficiency and gene duplication of Tbx5 are at the basis of the cardiac abnormalities associated with Holt?Oram syndrome (HOS). Recent data indicate that miRNAs might be an important part of the regulatory circuit through which Tbx5 controls heart development. Using high-throughput technologies, we characterized genome-widely the miRNA and mRNA expression profiles in WT- and Tbx5-depleted zebrafish embryos at two crucial developmental time points, 24 and 48 h post fertilization (hpf). We found that several miRNAs, which are potential effectors of Tbx5, are differentially expressed; some of them are already known to be involved in cardiac development and functions, such as miR-30, miR-34, miR-190, and miR-21. We performed an integrated analysis of miRNA expression data with gene expression profiles to refine computational target prediction approaches by means of the inversely correlation of miRNA?mRNA expressions, and we highlighted targets, which have roles in cardiac contractility, cardiomyocyte proliferation/apoptosis, and morphogenesis, cru- cial functions regulated by Tbx5. This approach allowed to discover complex regulatory circuits involving novel miRNAs and protein coding genes not considered before in the HOS such as miR-34a and miR-30 and their targets

Preferred Conformation and Membrane Activity of the LP237-F Lipopeptaibols

We have synthesized by solution methods and characterized the lipopeptaibol metabolite LP237-F8 extracted from the fungus Tolypocladium geodes and five selected analogues with the Etn\u2192Aib or Etn\u2192Nva replacement at position 8 and/or a triple Gln\u2192Glu(OMe) replacement at positions 5, 6, and 9 (Etn=C\u3b1-ethylnorvaline, Aib=\u3b1-aminoisobutyric acid, Nva=norvaline). Conformation analysis, performed by FT-IR absorption, NMR, and CD techniques, strongly supports the view that the six terminally blocked decapeptides are highly helical in solution. Helix topology and amphiphilic character are responsible for their remarkable membrane activity. At position 8 the combination of high hydrophobicity and C\u3b1 tetrasubstitution, as in the Etn-containing LP237-F8 metabolite, has a positive effect on membrane interaction