Effect of hypovolemia on traumatic spinal cord injury.

OBJECTIVES: Experimentally evaluate the effect of hypovolemia in acute traumatic spinal cord injury. METHODS: Twenty adult male Wistar rats were submitted to traumatic spinal cord injury through spinal cord contusion by direct impact. Ten animals were subjected to bleeding of 20% of their estimated blood to simulate a hypovolemic condition after spinal cord contusion and 10 animals were used as control. The animals were evaluated before, 1, 3, 7 and 14 days after the production of the spinal cord injury through behavioral tests (inclined plane test and motor assessment). RESULTS: The spinal cord contusion associated with hypovolemia had a negative influence on functional outcomes of the spinal cord injury. The animals submitted to hypovolemia after spinal cord contusion had lower scores in behavioral tests (inclined plane test and motor assessment), presenting a slower recovery of the motor function. CONCLUSION: In the experimental model used, the group of animals with hypovolemia after traumatic spinal cord injury had slower recovery and lower intensity in behavioral tests.

The taxonomic distinctness of macroinvertebrate communities of Atlantic Forest streams cannot be predicted by landscape and climate variables, but traditional biodiversity indices can.

Predicting how anthropogenic activities may influence the various components of biodiversity is essential for finding ways to reduce diversity loss. This challenge involves: a) understanding how environmental factors influence diversity across different spatial scales, and b) developing ways to measure these relationships in a way that is fast, economical, and easy to communicate. In this study, we investigate whether landscape and bioclimatic variables could explain variation in biodiversity indices in macroinvertebrate communities from 39 Atlantic Forest streams. In addition to traditional diversity measures, i.e., species richness, abundance and Shannon index, we used a taxonomic distinctness index that measures the degree of phylogenetic relationship among taxa. The amount of variation in the diversity measures that was explained by environmental and spatial variables was estimated using variation partitioning based on multiple regression. Our study demonstrates that taxonomic distinctness does not respond in the same way as the traditional used in biodiversity studies. We found no evidence that taxonomic distinctness responds predictably to variation in landscape metrics, indicating the need for the incorporation of predictors at multiple scales in this type of study. The lack of congruence between taxonomic distinctness and other indices and its low predictability may be related to the fact that this measure expresses long-term evolutionary adaptation to ecosystem conditions, while the other traditional biodiversity metrics respond to short-term environmental changes.