A series of 24 compounds of general formula R
1S-Hg-SR
2, R
1 and R
2 being biologically relevant thiol-containing amino acids and peptides (cysteine,
homo-cysteine, penicillamine,
N-acetyl-cysteine,
...N-acetyl-penicillamine, cysteinyl-glycine, γ-glutamyl-cysteine and glutathione) were prepared by direct reaction of mercury(II) ions and thiols in water at millimolar concentration. The obtained products were characterized by electrospray ionization and triple quadrupole tandem mass spectrometry. The source spectra of equimolar mixtures of two different thiols reacting with a stoichiometric amount of mercury(II) show the peak clusters of the three theoretically expected
bis-thiolato-mercury(II) complexes with relative intensities close to the theoretically expected 1:2:1 ratio, thus pointing at lack of substantial discrimination between the different thiols, the only observed exception being
homo-cysteine, which is less reactive than cysteine and penicillamine. The fragment spectra are structure-specific for the different ligands bound to the metal ion and allow a stand-alone discrimination of some constitutional isomer pairs. Among the peculiar fragmentation processes observed, loss of neutral ammonia from protonated symmetrical and unsymmetrical mercury(II)-
bis-thiolates with free, protonizable amino groups leads to the formation of thiirane-carboxylic bound species; this process is suppressed when the protonated amino group is in the γ-position with respect to the sulfur atom, as in the case of compounds with
homo-cysteine. This unusual behavior may hint at unforeseen mechanisms for the interaction of mercury(II) with biological structures, ultimately leading to cellular and organ toxicity. Compounds with
N-acetylated amino acids show distinctive fragment ions to which the connectivity of a protonated 2-methyl-oxazoline-5-carboxylic acid may be proposed on the basis of the loss of water and of the elements of formic acid. Finally, the adducts of mercury(II) with glutathione and γ-glutamyl-cysteine feature a distinctive decomposition channel by loss of a pyroglutamic unit, much the same as protonated glutathione, glutathione disulfide, the S-glutathionyl adducts of biologically occurring electrophiles and other (pseudo)-peptides with γ-glutamyl bonds.
A method for the determination of benzene, toluene, ethylbenzene and xylenes (BTEX) in urine of people exposed to these airborne pollutants present in the living environment, has been described. ...Solid-phase microextraction has been used for sampling BTEX from the headspace of urine and gas chromatography–mass spectrometry has been applied for the selective analysis of chemicals. The method has the following features: small volume of urine (2 ml) needed, linearity in the range of interest (from the limit of detection up to 5000 ng/l) with coefficient of correlation ≥0.998, limit of detection in the range 12–34 ng/l, good repeatability (coefficient of variation 2–7%), high specificity. The stability of the urine sample during storage (−20°C) was evaluated: BTEX remained stable for up to 2 months. The assay has been successfully applied to the biological monitoring of two subjects environmentally exposed to airborne BTEX in an urban area.
The
K = 800 CSC (Catania Superconducting Cyclotron) is now under commissioning at LNS 1. The accelerator was computer controlled since its first test. The control system has been realized according ...to a three level architecture. At field level, field-bus networks have been used as interface between the control stations and each device to be controlled. The process level has been implemented using
386
486
PCs
as control stations, each one dedicated to an accelerator sub-system according to functional criteria for the intelligence distribution. The control stations communicate with the upper level by means of a local area network. The supervisor level consists of a Vax-Stations Cluster and a modular code, based on Dec Window Motif, has been developed as man-machine interface. Experience and improvements for an efficient commissioning of a fully computer controlled accelerator will be reported together with the performance obtained.
Radon risk evaluation in a hospital context Urso, P; Pulvirenti, S; Sormani, I ...
Giornale italiano di medicina del lavoro ed ergonomia,
2011 Jul-Sep, Letnik:
33, Številka:
3 Suppl
Journal Article
Recenzirano
Italian legislation imposes radon concentration in occupational, underground premises as to not exceed the annual action level of 500 Bq/m3. A survey in a hospital of Milan founded concentrations ...never exceeding the action level, distribute around the median concentration of 16 Bq/m3, ranging between 6 e 214 Bq/m3 (Cmean = 38 +/- 50 Bq/m3). However, a pavilion, characterized by higher levels (C = 103 divided by 214 Bq/m3), was better studied by short-term monitoring, during summer and winter, confirming concentrations not exceeding legislative level, even if not negligible. Results underlines the importance of a monitoring strategy as punctual as possible. Moreover, shortterm measurements can represent a valid tool for premises screening in radon monitoring.
A superconducting cyclotron is now under development at LNS-Catania as a part of a heavy ion-facility. The features of the distributed control system of this accelerator and the experiences gained ...during its functioning will be reported together with its future improvements.< >
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