[New data on pumice's structure and biological effects among miners and millers]. / Nuove acquisizioni sull struttura dell pietra pmie e possibili effetti pleurici nei lavoratori del settore.

Pleural plaques among pumice workers on Lipari Island have been described and the Authors have suggested the hypothesis that such biological effect could be related to the particles' morphology characterized by the presence of elements similar to fibers. Analysis on compact bulk materials and on dust samples from different sites of the Island have been performed to obtain information on the chemical composition of such materials. The Scan Electron Microscopy (SEM) analyses confirm the presence of fibrous particles with a chemical structure similar to the Refractory Ceramic Fibers (RCF) composition. These results could explain the presence of plural plaques among the workers and new clinical and epidemiological evaluations of the potential effects associated to this exposure are needed.

[Asbestosis and microfiber role]. / Patologia da asbesto e ruolo delle microfibre.

Based on the predominant content of thin and short asbestos fibres in lung and mesothelioma tissues, it was recently stated (2005) that such fibres "appear to contribute to the causation of human malignant mesothelioma". In another study of the same year it was stated that fibres in the order of few microm length and 0.2 microm diameter are the sole able to induce mesothelioma. This scientific conclusions entail some implications from practical point of view. The enormous amount of information gained on asbestos in the last decades is based on the definition of a fibre as an alongated particle with an aspect-ratio of at least 3:1, a diameter < or = 3 microm and a length > or = 5 microm. These parameters were used up today to define occupational and in some case non-occupational limits. In which way can "reference" values be established if all lengths or only fibres shorter than 5 microm are considered? Nowadays we have no answer. Secondly, assuming a prevalent role of such fibres especially in mesothelioma cases, how can reliable estimates of past exposure obtained in a medico-legal context, since they have never been counted? Morever, how might he the employer responsibility assessed since short fibres were not measured by definition pathogenic, and this not measured, nor were there appropriate filtering systems up to the middle of the '80?

Monitoring propofol serum levels by rapid and sensitive reversed-phase high-performance liquid chromatography during prolonged sedation in ICU patients.

A quick and sensitive reversed-phase high-performance liquid chromatography (HPLC) method has been developed in order to determine the concentration of Propofol (2,6 diisopropylphenol) in human serum. Propofol can be isolated from serum by adding 0.5 mL precipitating solution. This consists of an acetonitrile and perchloric acid (67:33, v/v) mixture, which also contains dibutylphthalate (2 mg/100 mL) as internal standard. The sample is then mixed for 1 min on a vortex-mixer. The endogenous serum substances precipitated by acetonitrile and perchloric acid are further separated by centrifugation. The supernatant is directly injected into the HPLC system. A 250- x 4.6-mm column, packed with 10-microns Spherisorb reversed-phase octadecylsilane particles (C18), is used for chromatographic separation. The mobile phase consists of an acetonitrile-water mixture (67:33 ratio) with 0.4 mL acetic acid (pH 4). Propofol is monitored by a UV-visible detector at 270 nm and 0.1-0.002 absorbance units full scale (AUFS). The detection limit of Propofol (in human serum) is 0.1 mg/L for a 20-microL injection volume. The time of the assay is less than 20 min, including sample preparation.

Excretion kinetics of the rubber anti-oxidant N-isopropyl-N'-phenyl-p-phenylendiamine (IPPD).

Sixteen rubber vulcanizers using IPPD as anti-oxidant were monitored for the presence of the parent compound in the urine during two consecutive working weeks using HPLC for analysis. At least two components in the excretion kinetics could be demonstrated: a fast one, as end-shift urinary concentrations significantly exceeded before-shift ones, and a less rapid one, as before-shift values at the end of the week significantly differed from those determined at the beginning. A skin absorption experiment was also performed. It demonstrated three components in the excretion kinetics, with apparent half-times of approximately 3, 7 and 24 h. Excretion ceased 7 d after skin exposure.