Chronic, topical exposure to benzo[a]pyrene induces relatively high steady-state levels of DNA adducts in target tissues and alters kinetics of adduct loss.

Carcinogen-DNA adduct measurements may become useful biomarkers of effective dose and/or early effect. However, validation of this biomarker is required at several levels to ensure that human exposure and response are accurately reflected. Important in this regard is an understanding of the relative biomarker levels in target and nontarget organs and the response of the biomarker under the chronic, low-dose conditions to which humans are exposed. We studied the differences between single and chronic topical application of benzo[a]pyrene (BAP) on the accumulation and removal of BAP-DNA adducts in skin, lung, and liver. Animals were treated with BAP at 10, 25, or 50 nMol topically once or twice per week for as long as 15 weeks. Animals were sacrificed either at 24, 48, or 72 hr after the last dose at 1 and 30 treatments, and after 24 hr for all other treatment groups. Adduct levels increased with increasing dose, but the slope of the dose-response was different in each organ. At low doses, accumulation was linear in skin and lung, but at high doses the adduct levels in the lung increased dramatically at the same time when the levels in the skin reached apparent steady state. In the liver adduct, levels were lower than in target tissues and apparent steady-state adduct levels were reached rapidly, the maxima being independent of dose, suggesting that activating metabolism was saturated in this organ. Removal of adducts from skin, the target organ, was more rapid following single treatment than with chronic exposure. This finding is consistent with earlier data, indicating that some areas of the genome are more resistant to repair. Thus, repeated exposure and repair cycles would be more likely to cause an increase in the proportion of carcinogen-DNA adducts in repair-resistant areas of the genome. These findings indicate that single-dose experiments may underestimate the potential for carcinogenicity for compounds that follow this pattern.

Attitudes towards disability in education through the SSCI (2000-2011): a topical and bibliometric analysis

Introduction. The purpose of this study is to describe and characterize the international sci-entific output relating to “attitudes towards disability in education”, using a battery of bibliometric indicators that make it possible to analyze and monitor international scientific activity. Method. This ex post facto retrospective study analyzed 925 papers published in the Social Sciences Citation Index (SSCI) database during the period 2000-2011. Results. The number of publications increased steadily between 2006 and 2010. The results reported here include the most productive authors, the journals that deal with this topic, and the articles cited most often. An analysis of research types showed a tendency toward empiri-cal studies. A total of 18 categories were identified when considering article content, and the distribution of the research studies across stages of education was found to be uneven. Discussion and Conclusion. The results reveal a topic that is highly current in today’s scien-tific community, and offer us a view of the traits that have characterized research on "attitudes towards disability in education" for the last eleven years.