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The endothelium releases dilating autacoids, such as nitric oxide (NO), prostaglandins, and endothelium-derived hyperpolarizing factor (EDHF). Different mechanisms of interaction between these autacoids have been identified and are briefly reviewed here. NO, which dilates resistance vessels via the second messenger cGMP, also amplifies the responses to vasodilators, which act by elevation of cAMP (e. g., prostaglandins), in a synergistic manner. This amplification is most likely due to a cGMP-dependent inhibition of the breakdown of cAMP. An interaction of these autacoids can not only be found in vascular smooth muscle cells but also in the endothelium. A closer look towards the site of production reveals that prostacyclin attenuates the release of NO, which is achieved by a decrease of the intracellular calcium levels in endothelial cells. This feedback mechanism leads to enhanced NO formation after inhibition of cyclooxygenase. While NO does not seem to modulate prostaglandin dynthesis, it has been shown recently in coronary arteries that NO attenuates the release of EDHF. Under conditions of compromised NO formation EDHF might act via this mechanism as a second line of defense. This could help in maintaining endothelium-dependent vasodilation unless an altered smooth muscle responsiveness generally reduces the efficacy of endothelial vasodilators (including EDHF). Convincing experimental evidence for such an impaired relaxation of smooth muscle has been presented recently following exposure to elevated oxLDL levels.

This study examined the sexual dimorphism in variables of the foramen magnum in a modern German population. This includes measurements of the maximum width, the maximum length, the circumference and the area of the foramen magnum, which were taken using the imaging software OsiriX (v.4.1.1. 64 bit). The data set includes 200 cadavers (100 males, 100 females) that were autopsied during the years 2011–2013 at the Institute of Legal Medicine and Forensic Sciences, Charité–Berlin. Each variable examined showed clear sexual dimorphism with p < 0.001 significantly higher values in male individuals than in female individuals. To analyse sexual dimorphism in the sample univariate and multivariate discriminant function analyses were performed. The resulting formulas allow a sex classification after cross-validation with up to 74.7% accuracy for this population. The results and mean values raised in this study are compared with those of recent studies and highlight the importance of raising and following population-specific standards in forensic and anthropologic investigations so as to avoid biased and incorrect results.