OBJECTIVES: The Mikania laevigata extract (MLE) (popularly known in Brazil as "guaco") possesses anti-inflammatory properties. In the present study we tested the effects of MLE in a periodontitis experimental model in rats. We also investigated possible mechanisms underlying such effects. MATERIAL AND METHODS: Periodontal disease was induced by a ligature placed around the mandibular first molars of each animal. Male Wistar rats were divided into 4 groups: non-ligated animals treated with vehicle; non-ligated animals treated with MLE (10 mg/kg, daily); ligature-induced animals treated with vehicle and ligature-induced animals treated with MLE (10 mg/kg, daily). Thirty days after the induction of periodontal disease, the animals were euthanized and mandibles and gingival tissues removed for further analysis. RESULTS: Morphometric analysis of alveolar bone loss demonstrated that MLE-treated animals presented a decreased alveolar bone loss and a lower expression of the activator of nuclear factor-κB ligand (RANKL) measured by immunohistochemistry. Moreover, gingival tissues from the MLE-treated group showed decreased neutrophil migration myeloperoxidase (MPO) assay. CONCLUSIONS: These results indicate that MLE may be useful to control bone resorption during progression of experimental periodontitis in rats.

Avaliou-se a variabilidade e a estrutura de dependência espacial de atributos físico-hídricos do solo (volume total de poros - VTP, condutividade hidráulica saturada - k0, porosidade drenável - PD e conteúdo de água volumétrico na capacidade de campo - tetacc), na bacia hidrográfica do Ribeirão Marcela, representativa do domínio dos Latossolos na Região Alto Rio Grande, ajustando-se semivariogramas do tipo esférico e exponencial pelos métodos dos Quadrados Mínimos Ponderados (QMP) e Máxima Verossimilhança (MV). As amostras para caracterização físico-hídrica foram coletadas na camada de 0 a 0,15 m de profundidade, obedecendo a grids de 240 x 240 m e 60 x 60 m, totalizando 165 pontos amostrais. Os atributos VTP e tetacc apresentaram baixa variabilidade, com coeficiente de variação (CV) de 7,54 e 10,22 %, respectivamente, sendo a variabilidade do atributo PD média, com CV de 43,2 %, e alta para k0, com CV de 88,37 %. Todos os atributos apresentaram estrutura de dependência espacial, com forte grau para os atributos VTP, k0 e tetacc, com GD de 81,82, 75,31 e 82,61 %, respectivamente, e moderada para PD, com GD na ordem de 54,88 %. Os alcances para VTP, tetacc e PD foram da ordem de 1.000,0 m, enquanto o atributo k0 mostrou alcance de 77,46 m. Verificou-se desempenho similar entre os métodos empregados, sendo ambos indicados para ajuste de semivariogramas a atributos físico-hídricos do solo. Entre os modelos de semivariograma, baseando-se na autovalidação, o esférico seria indicado para os atributos VTP, k0 e tetacc, apresentando quadrado médio do erro na ordem de 0,00161; 0,2795 e 0,00155, respectivamente; e o exponencial, para o atributo PD, com quadrado médio do erro de 0,004070.

The spatial variability and spatial dependence structure of physical water soil attributes (total porosity - VTP, saturated hydraulic conductivity - k0, drainable porosity - DP and soil moisture at field capacity - thetacc) was evaluated for an Oxisol representative of Ribeirão Marcela watershed, in the Alto Rio Grande domain. Spherical and exponential semi-variograms were fitted by the weighted minimum square (WMS) and maximum likelihood (ML) methodologies. Undisturbed and disturbed physical water samples were collected from the 0-0.15 m layer for characterization, in grids of 240 x 240 m and 60 x 60 m, totaling 165 sampling points. VTP and thetacc presented low variability, with coefficients of variation (CV) of 7.54 % and 10.22 %, respectively. The mean DP variability was intermediate, with CV of 43.2 %, and was high for k0 with a CV of 88.3 %. All attributes presented spatial dependence structure, which was strong for VTP, thetacc and k0, with a dependence degree (DD), respectively, of 81.82, 75.31 and 82.61 %. The spatial dependence structure of DP was moderate with a DD of 54.66 %. The domains of VTP, thetacc and DP were around 1.000 m and for k0 it was about 77.46 m. The results of both methodologies were similar, so that both are recommendable for the fitting of semi-variograms to physical water soil attributes. Based on cross-validation, spherical semi-variograms can be indicated for VTP, thetacc and k0, with a Mean Square Error (MSE) close to 0.00161, 0.2795 and 0.00155, respectively, and the exponential model recommended for DP, with MSE of 0.004070.