1,721,008 research outputs found
Association of exposure to benzene and smoking with oxidative damage to nucleic acids by means of biological monitoring of general population volunteers
No full textIn this study, the validation of liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) isotopic dilution method for the determination of benzene and nicotine metabolites in urine was carried out. Limit of detection are 0.026 μg/L for S-phenylmercapturic acid (SPMA), 0.55 μg/L for t,t-muconic acid (t,t-MA), and 12.41 μg/L for the cotinine, and the relative combined uncertainty was also calculated. The study involves 446 healthy volunteer residents since at least 10 years in an area of central Italy. SPMA resulted to be strongly correlated with cotinine (p = 0.75), its concentration in smokers (93) being about ten times than in non/ex-smokers (197/156), while the t,t-MA of smokers is about twice the non/ex-smokers value. A cutoff value for the definition of smoker is set at 100 μg/g creat. Oxidative stress was studied in smokers and non- and ex-smokers by means of the determination of the biomarkers 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo), 8-Oxo-7,8-dihydroguanosine (8-oxoGuo), and 8-Oxo-7,8-dihydroguanine (8-oxoGua): no significant differences were found between smokers and non/ex-smokers, but when subjects are classified according to the cotinine cutoff value, a correlation in smokers’ urinary 8-oxodGuo is found with SPMA and cotinine (p = 0.60 and p = 0.57). Results were confirmed by chemometric analysis that also identified the experimental variables most contributing the discrimination as cotinine and t,t-MA
Chemometric study of the correlation between human exposure to benzene and PAHs and urinary excretion of oxidative stress biomarkers
Full text linkUrban air contains benzene and polycyclic aromatic hydrocarbons (PAHs) which have carcinogenic properties. The objective of this paper is to study the correlation of exposure biomarkers with biomarkers of nucleic acid oxidation also considering smoking. In 322 subjects, seven urinary dose biomarkers were analyzed for benzene, pyrene, nitropyrene, benzo[a]pyrene, and naphthalene exposure, and four effect biomarkers for nucleic acid and protein oxidative stress. Chemometrics was applied in order to investigate the existence of a synergistic effect for the exposure to the mixture and the contribution of active smoking. There is a significant difference between nicotine, benzene and PAH exposure biomarker concentrations of smokers and non-smokers, but the difference is not statistically significant for oxidative stress biomarkers. The PAH biomarkers are those which best correlate with all the oxidative stress biomarkers. Results suggest that 8-Oxo-7,8-dihydroguanine and protein nitro-oxidation 3-nitrotyrosine are the most sensitive biomarkers for the exposure to the urban pollutant mixtures and that a synergic effect of the mixtures exists. All the oxidative stress biomarkers studied drive the increase in the oxidative stress biomarkers in the subjects having higher exposures. Chemometrics proved to be a powerful method for the interpretation of human biomonitoring data
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Iodiocyclophosphamide as a possible internal standard in the analysis of antineoplastic drugs using mass spectrometry - Ciclofosfamide iodurata come possibile standard interno per l'analisi dei chemioteracipi antiblastici mediante spettrometria di massa
No full textAppropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Study on the interaction between the skin detoxifying enzyme glutathione S-transferase and the substances listed in the CE/39/2000 rules with the "skin" annotation, finalized to the biological monitoring of exposed subjects
No full textThe interaction among chemicals listed in the Directive CE/39/2000 with skin notation and glutathione S-transferase (GSTP1-1) was studied by following two different experimental approaches. The compounds were incubated with the purified GST isoenzyme GSTP1-1 as well as with the human keratinocytes (PR5) selectively expressing GSTP1-1. Some of the molecules affected the enzymatic activity of both the purified and the intracellular GSTP1-1. In particular, 1,2-dichlorobenzene (DCB), ethylbenzene (ETB), cumene, Sulphotep and 2-eptanone (2-EPT) behaved as inhibitors of the purified GSTP1-1 enzyme, with different inhibition properties according to molecular structure. With the exception of Sulphotep showing a Ki value of 0.2 mM, all compounds reported above were characterized by high Ki values (between 2 and 16 mM) and therefore by low affinity towards GSTP1-1. These results make unlikely the use of a biosensor, based on immobilized GSTP1-1, for the detection of these molecules. On the contrary, Sulphotep can be the object of future investigations. It has to be stressed that the above listed compounds were effective on human keratinocytes, at concentrations two order of magnitude lower than that effective on purified GSTP1-1. In particular, cumene and DCB triggered a clear increase of the intracellular GSTP1-1 activity at concentrations lower than 0.1mM. These interesting results let to hypothesize the use of GSTP1-1 present in the keratinocytes as a marker for biological monitoring of workers exposed to these compounds as well as to evaluate the skin permeability of toxic compounds, not yet identified with a skin notation
Correlation between environmental and biological monitoring in petrochemical industry operators.
No full textRisultati preliminari del Progetto
Feasibility study of biological monitoring of chemical agents by means of evaluation of the effects on their in vitro effects on the complement system
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