Determination of micronucleus frequency by acridine orange fluorescent staining in peripheral blood reticulocytes of mice treated topically with different lubricant oils and cyclophosphamide

To ascertain whether used and re-refined lubricant oil absorbed through the skin can produce a genotoxic effect or cytotoxicity in mouse bone marrow cells, we examined the induction of micronucleated erythrocytes of peripheral blood after cutaneous application. Both re-refined and used lubricant oils showed a weak but significant induction of micronucleated polychromatic erythrocytes compared with control, while virgin oil did not show micronucleus induction. Cyclophosphamide (CP) was used not only as positive control but also to compare the sensitivity between intraperitoneal and dermal routes of administration of the test compounds in mice. The efficacy of intraperitoneal injection of CP is well known. On the other hand, dermal exposure is not so common and when CP was diluted in glycerin statistically significant values (P = 0.0036) of micronuclei were also found. Topically applied lubricant oils (virgin, re-refined and used) have the capacity to interfere with mouse bone marrow hematopoiesis evidenced by a statistically significant decrease in the proportion of polychromatic erythrocytes in the peripheral blood. Physical and chemical analysis revealed that used oil is more viscous than other lubricants, suggesting the presence of insoluble compounds, oxidized products and water as well as aromatic hydrocarbons. Used oil differs from other lubricant oils in metal and polyaromatic hydrocarbon content. Re-refined oil revealed a neutral value typical of pure mineral oil. This assay is an important tool to evaluate environmental pollutants that cause genotoxicity and/or cytotoxicity through skin exposure.

The in vitro antiviral activity of isoprinosine on simian rotavirus (SA-11)

The antiviral effect of isoprinosine on simian rotavirus (SA-11) replication was studied using MA-104 cell cultures from Rhesus monkey fetal kidney. Isoprinosine (N,N-dimethylamino-2-propanol-p-acetamidobenzoate in association with inosine) added after viral infection (therapeutic test) inhibited viral replication by more than 90%. In these experiments, the drug was added to the medium and replaced daily at concentrations varying from 62.5 microng/ml to l mg/ml. Viral inhibition activity was dependent on drug concentration. No antiviral effect was observed when isoprinosine was tested without replacement (200-500 microng/ml). When isoprinosine (l mg/ml) was added to cell cultures only before viral infection (prophylactic test), inhibition of viral replication occurred but was less than 90%. Inhibition by less than 90% is not considered to be significant in this type of test. Isoprinosine inhibited synthesis of both viral antigen (protein) and viral double-stranded nucleic acid, as monitored by immunofluorescence and acridine orange staining, respectively. Inhibiton of synthesis of viral macromolecules increased with drug concentration