RESUMO
Understanding and predicting the likely response of ecosystems to climate change are crucial challenges for ecology and for conservation biology. Nowhere is this challenge greater than in the tropics as these forests store more than half the total atmospheric carbon stock in their biomass. Biomass is determined by the balance between biomass inputs (i.e., growth) and outputs (mortality). We can expect therefore that conditions that favor high growth rates, such as abundant water supply, warmth, and nutrient-rich soils will tend to correlate with high biomass stocks. Our main objective is to describe the patterns of above ground biomass (AGB) stocks across major tropical forests across climatic gradients in Northwestern South America. We gathered data from 200 plots across the region, at elevations ranging between 0 to 3400 m. We estimated AGB based on allometric equations and values for stem density, basal area, and wood density weighted by basal area at the plot-level. We used two groups of climatic variables, namely mean annual temperature and actual evapotranspiration as surrogates of environmental energy, and annual precipitation, precipitation seasonality, and water availability as surrogates of water availability. We found that AGB is more closely related to water availability variables than to energy variables. In northwest South America, water availability influences carbon stocks principally by determining stand structure, i.e. basal area. When water deficits increase in tropical forests we can expect negative impact on biomass and hence carbon storage.
Assuntos
Biomassa , Florestas , Temperatura , Clima Tropical , Água , Modelos Teóricos , América do SulRESUMO
PURPOSE: The objective of this study was to characterize and compare the morphological characteristics of the dura mater, the pericranium, and the temporal fascia to ascertain the most adequate tissue to use as a dura graft. METHODS: 20 dura mater, 20 pericranium and 20 temporalis fascia samples were analyzed. Each of the samples was stained with hematoxylin and eosin, orcein, Van Gieson, Masson's trichrome and Verhoeff-Van Gieson (600 slides in total) for a general morphological evaluation, as well as a quantitative, morphometric and densitometric analysis of elastic fibers present in each of the tissues. RESULTS: The micro-densitometric analysis of the tissues indicated that the area occupied by the elastic fibers showed values of 1.766 ± 1.376, 4.580 ± 3.041, and 8.253 ± 4.467 % for the dura mater, the temporalis fascia and the pericranium, respectively (p < 0.05, all pairs). The values observed in the analysis of the density intensity were 3.42E+06 ± 2.57E+06, 1.41E+07 ± 1.28E+07, and 1.63E+07 ± 9.19E+06 for the dura mater, the temporalis fascia and the pericranium, respectively (p < 0.05), dura mater vs. temporalis fascia and dura mater vs. pericranium). CONCLUSIONS: This is the first study to compare the dura mater with tissues for dural autograft and to quantify the elastic component present in these tissues. The results indicate that the temporalis fascia is a better dural graft because of its intrinsic tissue properties.
Assuntos
Autoenxertos/transplante , Dura-Máter/cirurgia , Fáscia/transplante , Periósteo/transplante , Procedimentos de Cirurgia Plástica/métodos , Retalhos Cirúrgicos/transplante , Adulto , Idoso , Cadáver , Densitometria , Dura-Máter/transplante , Humanos , Masculino , Pessoa de Meia-Idade , Crânio/anatomia & histologia , Músculo Temporal/anatomia & histologia , Adulto JovemRESUMO
A series of five cases with Wegener's granulomatosis (WG) is presented: two women and three men with an average age of 37 years old, with an average time of evolution of the disease of 5 years and systemic clinical presentation (respiratory, renal and ocular affection); the ANCA were positive; three of them were carriers of Staphylococcus aureus. All the patients received combined therapy composed by trimethoprim-sulfamethoxazole-cyclophosphamide (TMS-CFM) during approximately 29 months of follow- up, except for a pregnant patient. The patients showed a satisfactory clinical evolution with improvement of the manifestations of the disease. We suggest that, due to its benefits, the combination of TMS-CFM can be useful as a therapeutic alternative in WG.