Project description:Formaldehyde, an important industrial chemical, is used for multiple commercial purposes throughout the industrialized world. This simple, one carbon aldehyde is a natural metabolite formed in cells throughput the body. However, it is also a rodent nasal carcinogen, when inhaled by rats every day for two-years at irritant concentrations. High tumor incidences occur at concentration of 10 ppm and above; no tumors are observed at concentrations below 6.0 ppm. The US Environmental Protection Agency (US EPA) is now (2007) conducting a risk assessment to try to evaluate possible cancer risks for much lower levels of human exposure. Sensitive methods are needed to evaluate tissue responses below those concentrations that are clearly irritant or carcinogenic. This microarray study was undertaken to evaluate the mode of action for nasal responses to inhaled formaldehyde in Fisher 344 rats over a range of exposure concentrations. The range of concentrations used spanned those at which virtually no tissue responses were observed (0.7 ppm) to those that represent the highest concentration in the cancer studies (15 ppm) that produced nasal tumors in half the exposed group of rats. The study identified doses at which there were no statistically significant changes in gene expression; intermediate doses with changes in a small number of genes not easily grouped by function; and then concentrations where changes were consistent with irritation and cell stress responses. Experiment Overall Design: Eight week old male F344/NCrl rats were exposed to formaldehyde through either instillation or inhalation. For animals exposed via instillation, 40 ul per nostril of 400 mM formaldehyde was instilled intranasally. Vehicle control animals were instilled with 40 ul per nostril of distilled water. All animals exposed via instillation were sacrificed 6 hours post-exposure. For animals exposed via inhalation, whole-body exposures were performed at doses of 0, 0.7, 2, 6, and 15 ppm (6 hours per day, 5 days per week). Inhalation animals were sacrified at 6 hours, 24 hours, 5 days, and 19 days following initiation of exposure except for the 15 ppm concentration which was sacrificed at only the 6 hour time point. Following sacrifice, tissue from the Level II region of the nose was dissected and digested with a mixture of proteases to remove the epithelial cells. The epithelial cells scquired from this section of the nose consisted primarily of transitional epithelium with some respiratory epithelium. Microarray analysis was performed on the epithelial cells.
Project description:Formaldehyde (HCHO) is the simplest form of aldehyde and it is naturally present in a wide range of resources. In spite of its cosmopolitan presence, formaldehyde can have deleterious health effects at higher concentrations like leukemia. However, most of the studies carried out so far have focused on the effect of formaldehyde exposure through inhalation and not much has been studied on the its exposure through food. In this context, the present study was carried out to investigate the effect of formaldehyde exposure through drinking water on the liver proteome of rat which would not only be helpful in assessing the impact of formaldehyde on health of organisms but also would be helpful in understanding the mechanism of detoxification.
Project description:We set out to test the hypothesis that formaldehyde inhalation exposure significantly alters miRNA expression profiles within the nasal epithelium of nonhuman primates. Here, cynomolgus macaques were exposed to 0, 2, and 6 ppm formaldehyde for 6 hours/day across two consecutive days. RNA was extracted from the nasal maxilloturbinate region, a direct target of formaldehyde inhalation exposure. Genome-wide miRNA expression levels were assessed using microarrays.
Project description:We set out to test the hypothesis that formaldehyde inhalation exposure significantly alters miRNA expression profiles within the nasal epithelium of nonhuman primates. Here, cynomolgus macaques were exposed to 0, 2, and 6 ppm formaldehyde for 6 hours/day across two consecutive days. RNA was extracted from the nasal maxilloturbinate region, a direct target of formaldehyde inhalation exposure. Genome-wide miRNA expression levels were assessed using microarrays. Cynomolgus macaques (Macaca fascicularis) were exposed to 0, 2 and 6 ppm formaldehyde for 6 hours/day across two consecutive days using whole body exposure chambers. RNA was extracted from the nasal maxilloturbinate region, a direct target of formaldehyde inhalation exposure. Genome-wide miRNA expression levels were assessed using microarrays.