The Role of Micronucleus Assay to Detect Genetic Instability in Respiratory Cancer Patients.

Asbestos represents the main risk factor for malignant pleural mesothelioma (PM) even if only a minority of exposed people develop this tumor, suggesting a significant role for genetic susceptibility. This study aims to evaluate micronuclei (MN) frequency as a biomarker of genome instability in peripheral blood lymphocytes of PM and lung cancer (LC) patients when compared with healthy controls (HCs) and patients with nonneoplastic respiratory diseases (RDs). Lymphocyte cytokinesis-block MN assay was carried out on 317 subjects. Mutagen sensitivity, measured by quantifying MN frequency after an in vitro challenge with ionizing radiation, was evaluated in 252 subjects. A significant increase in MN frequency was observed in cancer patients compared to HCs, with a mean ratio (MR) of 1.35 and 1.36 at baseline and 1.43 and 1.38 after irradiation in PM and LC patients, respectively. A positive (synergistic) interaction between asbestos exposure and disease status was observed for MN frequency after irradiation in PM patients with possible exposure to asbestos (MR = 1.62). The evidence of increased genetic damage in cancer cases confirms lymphocyte cytokinesis-block MN assay as a sensitive predictor of the role of genetic instability in carcinogenic processes.

"Normal values" for the lymphocyte cytokinesis-block micronucleus cytome parameters: Repeatability and reproducibility in a healthy reference population.

The micronucleus test in peripheral blood lymphocytes is the most widely validated technique to evaluate the DNA damage and chromosomal instability in human populations. The test is largely applied in monitoring environmental and occupational exposure to genotoxic agents. It was also proposed as a biomarker of risk/susceptibility for cancer and other degenerative diseases. The availability of "normal values" in healthy populations is a main requisite for the assay application in human biomonitoring. Age and gender-related ranges of micronucleated binucleated cells (MNBN) baseline values were established in a group of 103 healthy platelet donors (50 males and 53 females) not recently exposed to genotoxic agents and characterized for demographic, lifestyle and dietary factors. Repeatability of the test by the same scorer was evaluated. Reproducibility was estimated through analysis of repeated blood samples. High correlation between the results of the three blood samplings in two separate scoring sessions of MNBN/1000BN (R2 values were 0.83, 0.74 and 0.68; P < 0.0001) and PI values (R2 values were 0.69, 0.62 and 0.65; P < 0.0001) was detected. High consistency among the values obtained in three different samplings in the same individual was observed (Intraclass Correlation Coefficient (ICC) = 0.905, (95% CI = 0.868-0.933, P < 0.0001) The range of "normal" values predicted on the basis of the results of the present study appears to be sufficiently narrow to warrant application of the assay in the comparison of data obtained from groups of exposed or susceptible subjects, supporting its use in preventive programs. The large inter-individual variability predicted by the model used in the present study hampers a clinical application of the assay at individual level. The method applied in the present study represents a generally applicable model to derive "normal values" in any population, as an essential step before starting a biomonitoring study.

Aquatic ecology of the oyster pathogens Vibrio splendidus and Vibrio aestuarianus.

The ecology of the oyster pathogens Vibrio splendidus and Vibrio aestuarianus in the brackish aquatic environment was extensively investigated in this study. By conducting laboratory experiments under natural setting conditions, it was shown that V. splendidus LGP32 strain generally exhibits longer persistence in both seawater and sediment than V. aestuarianus 01/32 strain. Both strains maintained viability and culturability for longer times in the sediment, suggesting that this compartment may represent a suitable niche for their persistence in the environment. In addition, both strains attached to chitin particles and copepods, the efficiency of attachment being higher in V. splendidus than in V. aestuarianus. Similarly, LGP32 strain showed a greater capability to form biofilm on poly-vinyl chloride (PVC) surfaces than 01/32 strain. LGP32 and 01/32 strains were also capable of entering a viable but non-culturable state after extended incubation at 5°C, a condition commonly found during cold season in the aquatic brackish environment. These results are consistent with field data collected during a 2-year sampling campaign in the northern Adriatic Sea and provide background information on the mechanisms promoting V. splendidus and V. aestuarianus persistence in coastal water, thus contributing to a better understanding of the epidemiology of the associated diseases.