Freshwater resources are increasingly scarce due to human activities, and the understanding of water quality variations at different spatial and temporal scales is necessary for adequate management. Here, we analyze the hypotheses that (1) the presence of a wastewater treatment plant (WWTP) and (2) a polluted tributary that drains downstream from the WWTP change the spatial patterns of physicochemical variables (pH, turbidity, dissolved oxygen, and electrical conductivity) and nutrient concentrations (reactive soluble phosphorus, total phosphorus, nitrogen series, total nitrogen, and total dissolved carbon) along a mid-order river in SE Brazil and that these effects depend on rainfall regime. Six study sites were sampled along almost 4 years to evaluate the impacts of human activities, including sites upstream (1-3) and downstream (5-6) from the WWTP. The impacts were observed presenting an increasing trend from the source (site 1) towards Água Quente stream (site 4, the polluted tributary), with signs of attenuation at site 5 (downstream from both WWTP and site 4) and the river mouth (site 6). Input of nutrients by rural and urban runoff was observed mainly at sites 2 and 3, respectively. At sites 4 and 5, the inputs of both untreated and treated wastewaters increased nutrient concentrations and changed physicochemical variables, with significant impacts to Monjolinho River. Seasonal variations in the measured values were also observed, in agreement with the pluviometric indexes of the region. Univariate analyses suggested no effect of the WWTP for most variables, with continued impacts at sites downstream, but non-parametric multivariate analysis indicated that these sites were recovering to chemical characteristics similar to upstream sites, apparently due to autodepuration. Therefore, multivariate methods that allow rigorous tests of multifactor hypotheses can greatly contribute to determine effects of both point and non-point sources in river systems, thus contributing to freshwater monitoring and management.
In order to investigate an alternative way to correct diaphysial bone defects, granulated decalcified homologous cortical bone was used as a graft. Because of the suitable anatomic arrangement, the forearm of rabbits was chosen as an experimental model of bone defect. A 2 cm long bone cylinder was removed from the diaphysis of both radii preserving the periosteum. The artificial bone defect was filled with granular decalcified bone on the right side. The left side was used as control and kept empty or filled with undecalcified granular bone. The 18 animals were sacrificed in batches, 3,6, and 9 weeks after the operation. New bone formation was followed by X-rays, routine histology and incorporation of calcein blue, xylenol orange and tetracycline. In the decalcified granular bone grafts new bone formation was already detected at the first week and 9 weeks after the graft operation there was a well developed cylindric ossicle, in 89% of the cases. In some cases a medullary canal was present. No bone formation was found neither in the empty defects nor in the ones filled with undecalcified granular bone grafts.
The integration of immature cartilage allografts to knee joints of both normal rabbits and those submitted to arthritis through papain was studied for a period of up to 9 months. Two types of grafts were compared: chondral--constituted only by cartilage, and osteochondral--cartilage plus a thin layer of subchondral bone. The integration of the grafts was analyzed through inspection of the articular surface and histologic sections. The viability of the grafts was checked through the incorporation of 35SO4 on the chondral matrix. The following conclusions were drawn: (1) A large member of the grafted cartilages were well accepted without histological evidence of immunological rejection, and metabolically active 9 months after transplantation. (2) The chondral graft was found to be superior to the osteochondral one regarding the integration, but both showed tendency to degeneration with time. (3) The presence of arthritis previously induced by papain affected the integration of the grafts causing a higher precentage of degeneration on the grafts causing a higher precentage of degeneration on the grafted cartilage.
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