Cytotoxicity and expression of genes involved in the cellular stress response and apoptosis in mammalian fibroblast exposed to cotton cellulose nanofibers

Cellulose nanofibers (CNF) have mechanical properties that make them very attractive for applications in the construction of polymeric matrices, drug delivery and tissue engineering. However, little is known about their impact on mammalian cells. The objective of this study was to evaluate the cytotoxicity of CNF and their effect on gene expression of fibroblasts cultured in vitro. The morphology of CNF was analyzed by transmission electron microscopy and the surface charge by Zeta potential. Cell viability was analyzed by flow cytometry assay and gene expression of biomarkers focused on cell stress response such as Heat shock protein 70.1 (HSP70.1) and Peroxiredoxin 1 (PRDX1) and apoptosis as B-cell leukemia (BCL-2) and BCL-2 associated X protein (BAX) by RT-PCR assay. Low concentrations of CNF (0.02-100 μg ml(-1)) did not cause cell death; however, at concentrations above 200 μg ml(-1), the nanofibers significantly decreased cell viability (86.41 ± 5.37%). The exposure to high concentrations of CNF (2000 and 5000 μg ml(-1)) resulted in increased HSP70.1, PRDX1 and BAX gene expression. The current study concludes that, under the conditions tested, high concentrations (2000 and 5000 μg ml(-1)) of CNF cause decreased cell viability and affect the expression of stress- and apoptosis-associated molecular markers.

[Poliomyelitis in Sergipe]

A retrospective study of poliomyelitis in Sergipe, Northeast of Brazil, is presented by the authors. The study was divided in three periods, taking in consideration the notification rate of positive cases and emphasizing the period from 1979 to 1989 through the study of 159 consecutive cases. The following information was gathered for each case: sex, age, origin, former immunization status and clinical development. Also evaluated were annual incidence, relationship of incidence/vaccinal coverage and geographic distribution. Comments were made about the change in the wild poliovirus circulation (P1 to P3) and about epidemiological outbreaks occurred in 1984 and 1986, and problems related to the lack of immunity in children with complete vaccinal scheme. Poliomyelitis was considered to be controlled in the State of Sergipe but the necessity of maintenance of effective epidemiological vigilance for all cases of acute and flabby paralysis in children under 14 years is emphasized.