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Tree growth models describe the growth and development of forest ecosystems by considering how the dimensions of each simulated tree change within a certain time. These models have commonly used three growth parameters that describe various biological processes and behaviours, considering a sigmoid growth function: (i) the upper asymptote (θ1), which is the maximal yield indicated by a final dimension (such as the maximal stem diameter); (ii) the maximum specific growth rate (θ2), defined as the slope of the tangent at the inflexion point; and (iii) the time elapsed (θ3), defined by the intercept of this tangent with the abscissas. To the best of our knowledge, however, associations between the three parameters have not been documented for tree species. Using diameter growth data from pine trees located in typical mixed and uneven-aged pine-oak forests in the Sierra Madre Occidental, Mexico, our study aims were: (i) to quantify the putative associations between the three growth parameters and (ii) to test the accuracy of a proposed Hybrid Chapman-Richards growth model based on associations between the three growth parameters, but including only one single parameter, relative to the widely used Generalized Algebraic Difference Approach (GADA) based on the Chapman-Richards, Lundqvist and Hossfeld models and the Hybrid Weibull Model. For statistical comparison of the quality of the models, we used the mean relative percentage error, root mean square error, coefficient of determination and Akaike information criterion to assess the quality of the fit. Although the quality of the five growth models studied was similar, from a practical point of view, the proposed Hybrid Chapman-Richards Model (CR-H) is easier to apply than the other models and has a lower data collection and computational cost. The parameter of CR-H can be easily obtained, by measuring just the dominant trees, especially in coniferous forests with irregular ages. Moreover, in contrast to the Chapman-Richards-GADA factor χ0, when θ2 is assumed to be site-specific, the CR-H has always a closed-form solution.

Osteoarthritis (OA) is the most common joint disease in both humans and animals, and it results in movement restriction and pain at the affected area. This disorder affects more than 25% of people over 60 years of age, and it is considered universal for 70-year-old people. OA is estimated to affect over 20% of the canine population from the United States of America. The present study aimed to evaluate the treatment of rats that were surgically induced to OA using two different drug therapies, one with pentosan polysulfate, one with betamethasone, and one with chondroitin sulfate/ glucosamine. In order to produce joint disease, the cranial cruciate ligament was surgically transected. Animals were kept and treated for eight days after surgery and were assessed via both radiographies and tomographies taken before surgery and eight weeks later. All animals were euthanized having both macroscopic and microscopic analysis performed to evaluate the disorder progression and therapeutic action. Macroscopic analysis showed lesion in the knees subjected to OA induction. The untreated animals presented major lesions whereas the treated ones presented mild to moderate lesions. In conclusion, pentosan polysulfate is recommendable for the treatment of iatrogenic joint lesions in rats since the other treatments showed no significant difference. A osteoartrite (OA) é a doença articular mais comum em humanos e animais, o que ocasiona restrição de movimentos e dor, na região acometida. Tal enfermidade afeta mais de 25% dos humanos acima de 60 anos e, aos 70 anos, ela é considerada universal. Estima-se que nos Estados Unidos da América, 20% ou mais da população canina é acometida pela OA. O presente estudo tem como finalidade avaliar a terapia medicamentosa (polisulfato de pentosano, betametasona e sulfato de condroitina/glucosamina), em um modelo experimental de OA cirurgicamente induzido, em ratos. A doença articular foi promovida pela transecção cirúrgica do ligamento cruzado cranial, sendo que, após o procedimento cirúrgico, os animais foram mantidos e tratados por oito semanas. Foi realizada avaliação radiográfica e tomográfica antes e oito semanas após a indução da osteoartrite. Todos os animais foram submetidos à eutanásia para análise macroscópica e microscópica, que foram realizadas para avaliar a progressão da enfermidade e a ação terapêutica. Na análise macroscópica foi observadas lesões nos joelhos submetidos à indução OA. Os animais não tratados apresentaram lesões graves enquanto que, os animais tratados apresentaram lesões leves a moderadas. Concluiu-se que o polissulfato de pentosano é eficiente no tratamento de lesões articulares iatrogênicas de ratos, uma vez que outros tratamentos não mostraram qualquer diferença significativa.