Aortic arch baroreceptor stimulation in an experimental goat model: a novel method to lower blood pressure

The effect of aortic baroreceptor stimulation on blood pressure manipulation was assessed using the goat species Capra aegagrus hircus. The aim of this study was to manipulate blood pressure with future intention to treat high blood pressure in humans. The ages of the animals ranged from 6 months to 2 years. A standard anesthesia protocol was used. A lateral thoracotomy was performed to gain access to the aortic arch. Data was collected with the Vigileo system. Pre stimulation blood pressure was compared with maximum post stimulation blood pressure values. Results were analyzed with the Wilcoxon signed rank test. In the study 38 animals were enrolled. Baroreceptor stimulation was performed for each animal using 3 different electrodes each of which emits an electrical impulse. In the pilot phase of the study, the median baseline blood pressure prior to stimulation of the baroreceptors was 110.8 mmHg. After stimulation the median blood pressure decreased to 88 mmHg. The average decrease in blood pressure was 22.8 mmHg. This decrease of blood pressure after stimulation of the baroreceptors is statistically significant (p < 0.0001) and the proof of concept was shown. During the extended phase all three probes had a significant effect on blood pressure lowering (p < 0.0001). The study confirmed that aortic baroreceptor stimulation has an effect on blood pressure lowering. This is a novel field of blood pressure manipulation. The hemodynamic effects of long-term aortic baroreceptor stimulation are unknown. Further investigations need to be done to determine whether a similar effect can be induced in different species such as primates and humans

Changes to the Fossil Record of Insects through Fifteen Years of Discovery

The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well