Epoxy composite dusts with and without carbon nanotubes cause similar pulmonary responses, but differences in liver histology in mice following pulmonary deposition.

BACKGROUND: The toxicity of dusts from mechanical abrasion of multi-walled carbon nanotube (CNT) epoxy nanocomposites is unknown. We compared the toxic effects of dusts generated by sanding of epoxy composites with and without CNT. The used CNT type was included for comparison. METHODS: Mice received a single intratracheal instillation of 18, 54 and 162 µg of CNT or 54, 162 and 486 µg of the sanding dust from epoxy composite with and without CNT. DNA damage in lung and liver, lung inflammation and liver histology were evaluated 1, 3 and 28 days after intratracheal instillation. Furthermore, the mRNA expression of interleukin 6 and heme oxygenase 1 was measured in the lungs and serum amyloid A1 in the liver. Printex 90 carbon black was included as a reference particle. RESULTS: Pulmonary exposure to CNT and all dusts obtained by sanding epoxy composite boards resulted in recruitment of inflammatory cells into lung lumen: On day 1 after instillation these cells were primarily neutrophils but on day 3, eosinophils contributed significantly to the cell population. There were still increased numbers of neutrophils 28 days after intratracheal instillation of the highest dose of the epoxy dusts. Both CNT and epoxy dusts induced DNA damage in lung tissue up to 3 days after intratracheal instillation but not in liver tissue. There was no additive effect of adding CNT to epoxy resins for any of the pulmonary endpoints. In livers of mice instilled with CNT and epoxy dust with CNTs inflammatory and necrotic histological changes were observed, however, not in mice instilled with epoxy dust without CNT. CONCLUSIONS: Pulmonary deposition of epoxy dusts with and without CNT induced inflammation and DNA damage in lung tissue. There was no additive effect of adding CNT to epoxies for any of the pulmonary endpoints. However, hepatic inflammatory and necrotic histopathological changes were seen in mice instilled with sanding dust from CNT-containing epoxy but not in mice instilled with reference epoxy.

A novel fixative improves opportunities of nucleic acids and proteomic analysis in human archive's tissues.

All tissues from biopsy or surgery origin are fixed and paraffin embedded as a routine procedure in the hospital departments of pathology. The traditional method of tissue preservation is the fixation in formalin, followed by paraffin embedding. In this way tissue's integrity is ensured also for future analyses, because there is no further chemical degradation of nucleic acids and proteins in tissues embedded in paraffin. After few sections for the histopathological examination the tissues are stored for decades in the hospital archives. Even if formalin fixation compromises the quality and integrity of nucleic acids, it has already been demonstrated that it is possible to recover and analyze DNA and RNA from these archive's tissues, even of autopsy origin. Protein analysis is on the contrary completely blocked, due to the fact that formalin fixation creates covalent links between proteins and the only way to study protein expression is immunohistochemistry. In this study we present our results concerning the use of a new formalin free fixative, the FineFIX. After extraction of nucleic acids, PCR and RT-PCR analyses were performed in DNA and RNA respectively. For DNA analysis it was possible to obtain amplicons of 2400 bps, while in formalin-fixed samples the maximum length achieved was less than 400 bps. RT-PCR analysis show that it was possible to study RNA fragments of 600 bps from FineFIX fixed tissues, against a maximum length of about 150 bps achieved by formalin-fixed tissues. These tissues were analyzed also by Western Blot analysis, showing that the proteins obtained from FineFIX treated samples are amenable and comparable in quality with those obtained from fresh frozen tissues. Protein extracts from FineFix treated tissues were also compared with fresh tissues'ones by two dimensional electrophoresis, demonstrating that the protein pattern were well comparable for number and distribution of the spots.