Effect of nicotine in matrix mineralization by human bone marrow and Saos-2 cells cultured on the surface of plasma-sprayed titanium implants.

Smoking has an established negative impact in the clinical outcome of dental implants. This work analyses the response of human osteoblastic cells to nicotine, at the surface of plasma-sprayed commercial titanium implants. Human bone marrow (HBM) and Saos-2 cells, seeded on the surface of titanium implants and cultured in experimental conditions favoring osteoblastic differentiation, were exposed continuously to nicotine (0.0001 to 0.5 mg mL(-1)) and characterized for cell proliferation and function. Exposure of HBM cells resulted in increased cell proliferation, higher alkaline phosphatase (ALP) activity, and earlier onset of matrix mineralization at levels up to 0.2 mg mL(-1), an initial inhibitory effect in cell growth and functional activity followed by a recovery in the presence of 0.3 mg mL(-1) and a dose-dependent deleterious effect at higher levels. By contrast, exposure to nicotine did not affect cell proliferation of Saos-2 cells at levels up to 0.2 mg mL(-1), and caused only a small positive effect in ALP activity in the presence of 0.05 and 0.1 mg mL(-1); however, matrix mineralization by Saos-2 cells also occurred earlier in the cultures exposed to levels of nicotine up to 0.1 mg mL(-1). Higher concentrations caused dose-dependent inhibitory effects. Considering the high diffusion potential of nicotine, results suggest a local role of nicotine in modulating bone formation events at the implant surface.

[Communication related to pesticides use in a rural area of the state of Rio de Janeiro, Brazil]. / Comunicação relacionada ao uso de agrotóxicos em região agrícola do Estado do Rio de Janeiro.

OBJECTIVE: To assess communications aspects related to pesticide use in a rural area of the Rio de Janeiro state, Brazil. METHODS: The study was carried out in the area of São Lourenço stream. It was based on methodological triangulation comprising: semi-structured interviews and observation of a local population sample (about 600 inhabitants); structured questionnaire to collect data on the local community; and records of lectures given by argonomic engineers, pesticides traders and other public service professionals. RESULTS AND DISCUSSION: This study pointed out to the historical misinformation on pesticides in rural areas; the emphasis on technical language in educational and training activities available which constitutes a barrier for rural workers knowledge acquisition and empowerment; and the industry/commerce's pressure to legitimate pesticide trading, reinforcing the existing communication process, resulting in unfavorable inclusion of the rural worker into a broader market economy.