[Comparative study on HAV and Poliovirus 2 inactivation cinetics with peracetic acid]. / Studio comparativo sulle cinetiche d'inattivazione dell'HAV e del Poliovirus 2 con acido peracetico. Nota I.

Hepatitis A virus and Poliovirus 2 inactivation tests were carried out using three peracetic acid concentrations (160, 320 and 640 mg/l) at different pH condition and at +20 degrees C temperature. HAV HM-175 strain was grown in FRhK4 cells and titrated in PFU (plaque technique) and the Poliovirus 2 strain was grown in monkey kidney cells RC-37 and titred in TCID50. The viral titration reduction was determined in the space of an hour with the disinfectant contact at 10-15 minutes intervals. The results obtained with the hepatitis A virus have shown a good linear trend between viral titration and contact time at the highest concentrations without any particular pH influence. The complete viral activity absence was achieved after 30-60 minutes of contact at 640 mg/l concentration. As regards Poliovirus 2 a good linear trend was highlighted between titrations and times at all the concentrations in shorter times at pH acid. The complete viral activity absence was obtained with 640 mg/l concentration after 30 minutes at pH acid. The HAV seems to own a higher resistance than Poliovirus 2 and Poliovirus 1 too.

[In vitro study of the nephrotoxic mechanism of mercuric chloride]. / Studio in vitro dei meccanismi di nefrotossicità del cloruro di mercurio.

OBJECTIVES: Mercury (Hg), one of the most diffused and hazardous organ-specific environmental contaminants, exists in a wide variety of physical and chemical states, each of which with unique characteristics of target organ specificity. Exposure to Hg vapour and to organic mercurials specifically affects the CNS, while the kidney is the target organ for inorganic Hg compounds. Despite the increasing number of studies, the molecular bases of the nephrotoxic potential of Hg has not, up to now, been clarified, even if there is evidence suggesting that the ability of the metal to interact with proteins (thiol groups) or to generate oxygen radicals may play a major role. Within this context, the aim of the present study was to investigate, in vitro, the mechanism(s) of the early nephrotoxic potential of mercury chloride (HgCl2), one of the most diffused and biologically active mercury (Hg2+) compounds. For this purpose, two kidney-derived in vitro systems (the MDCK and the LLC-PK1 cell lines) were tested for their sensitivity to the salt, and MDCK was chosen as the most suitable in vitro model for our study. As possible biological markers of the organ-specific toxicity of the metal we analysed: i) critical biochemical parameters related to oxidative stress conditions (effect of Hg2+ on the anti-oxidant status of the cell), and ii) gap-junctional function (GJIC). METHODS: Classical toxicity tests (MTT and NR) were used for assessing the sensitivity (IC50) of LLP-CK1 and MDCK cell lines to the mercuric salt. Complete solubilisation of the salt in the culture media was verified by inductively coupled plasma mass spectrometry (ICP-MS). The influence of the metal on cell growth rate and viability were evaluated by conventional proliferation assays. For the following mechanistic studies, cells were exposed for different time periods (4 to 72 hours) to non-cytotoxic (0.1-50 microM) HgCl2 concentrations. The biochemical analysis of the pro-oxidant properties of the mercuric compound was performed by the measurement of anti-oxidant cellular defences against H2O2 [catalase (Cat), glutathione peroxidase (Gpx), and total glutathione (GSH)]. The influence of the metal on the GJIC capacity of MDCK cells was assessed by the "microinjection/dye-coupling" assay. RESULTS: Among the two kidney-derived in vitro systems, MDCK cell line was the most specifically sensitive to the toxic effect of HgCl2: it was, consequently, chosen as a "tubular cell model" for the following experimental steps. Tested for various time periods at increasing concentrations, the HgCl2 effect on MDCK cell proliferation and viability was found to be time- and dose-related. For concentrations < or = 50 microM, HgCl2 inhibits MDCK cell growth rate, being this effect significant (> 50% in respect to untreated controls) from the 24th from the beginning of the treatment, while, for concentrations > 50 microM, the metal causes cell death. Concerning the influence of HgCl2 on MDCK anti-oxidant defences, the most interesting results were obtained by analysing the influence of the mercury salt on the GSH cell content and Gpx activity. Both were, in fact, significantly affected by the presence of the mercury ion. HgCl2 also induced a rapid, dose- and time-related inhibitory effect on the GJIC capacity of the cells. CONCLUSIONS: Even if further investigations are needed to better clarify the possible causal relationship between our findings, they indicate that: a) MDCK cells represent a suitable in vitro model for the study of Hg nephrotoxicity; b) GJIC function is, among those considered in our study, one of the most sensitive biological endpoints for investigating the mechanism(s) of Hg2+ specific toxicity.

The ability by different preparations of porcine parvovirus to enhance humoral immunity in swine and guinea pigs.

The capacity of different preparations of inactivated porcine parvovirus to stimulate antibody response was studied. The adjuvants chosen were aluminium hydroxide gel [Al(OH)3, 30-50%], water-in-mineral-oil emulsion (w/Mo, 50%) alone or combined with Al(OH)3, and two synthetic products known as dimethyldioctadecylammoniumbromide (DDA, 0.16%) and an acrylic acid polymer resin (Carbopol 934P, 0.02%) respectively. For each preparation, swine and guinea pigs devoid of antibody to porcine parvovirus were inoculated. Among all the preparations tested, two of them i.e. emulsified Al(OH)3 adsorbed antigen and Carbopol 934P emulsified virus, gave the most significant antibody response in animals, without any difference being noted in the behaviour of the two animal species.