Is arginine/asymetric dimethylarginine ratio depletion an indicator of insufficient resuscitation in a porcine model of hemorrhage-reperfusion?

Background: Hemorrhagic shock leads to a complex cascade of metabolic and hormonal processes that may result in hypoperfusion, end organ damage, and death even when blood pressure is restored. Studies have shown that morbidity and mortality could be attributable to a diminished availability of endothelial-derived nitric oxide (eNO). It is unclear whether adequate levels of citrulline (CIT) and arginine (ARG)--the precursors of eNO synthesis--are available to sustain the eNO needed to maintain adequate perfusion in severe shock.

Photoperiod affects estrogen receptor alpha, estrogen receptor beta and aggressive behavior.

Estrogens have important effects on male and female social behavior. Despite growing knowledge of the anatomy and behavioral effects of the two predominant estrogen receptor subtypes in mammals (ERalpha and ERbeta), relatively little is known about how these receptors respond to salient environmental stimuli. Many seasonally breeding species respond to changing photoperiods that predict seasonal changes in resource availability.

Photoperiod reverses the effects of estrogens on male aggression via genomic and nongenomic pathways.

Despite recent discoveries of the specific contributions of genes to behavior, the molecular mechanisms mediating contributions of the environment are understudied. We demonstrate that the behavioral effects of estrogens on aggression are completely reversed by a discrete environmental signal, day length. Selective activation of either estrogen receptor alpha or beta decreases aggression in long days and increases aggression in short days.