The placenta is metabolically active and supports the growth of the fetus. We hypothesize that deficits in the capacity of the placenta to maintain bioenergetic and metabolic stability during pregnancy may result in spontaneous preterm birth (SPTB). To explore this hypothesis, we performed a nested cased control study of metabolomic signatures in placentas from women with SPTB (<36 weeks gestation) compared to normal pregnancies (≥38 weeks gestation). To control for the effects of gestational age on placenta metabolism, we also studied a subset of metabolites in non-laboring preterm and term Rhesus monkeys. Comprehensive quantification of metabolites demonstrated a significant elevation in the levels of amino acids, prostaglandins, sphingolipids, lysolipids, and acylcarnitines in SPTB placenta compared to term placenta. Additional quantification of placental acylcarnitines by tandem mass spectrometry confirmed the significant elevation in SPTB human, with no significant differences between midgestation and term placenta in Rhesus macaque. Fatty acid oxidation as measured by the flux of ³H-palmitate in SPTB placenta was lower than term. Collectively, significant and biologically relevant alterations in the placenta metabolome were identified in SPTB placenta. Altered acylcarnitine levels and fatty acid oxidation suggest that disruption in normal substrate metabolism is associated with SPTB.

Simulation-based education has been shown to be an effective tool to mitigate skill decay. However, many of the strategies reported in the literature have overlapping terminology with little consensus on the timing of the strategy to prevent skill decay. In this review, we propose and provide a standardized nomenclature and framework for simulation strategies used to obtain, maintain, or regain skills that are decaying. This framework delineates four types of training: initial, maintenance, booster, and refresher. The framework differentiates these training types based on the learner competency at the time of the training, as well as the frequency and intensity of the training. Initial training is aimed at “novice” learners with the goal to achieve competency. Once competency is achieved, maintenance training prevents skill deterioration through low-dose high-frequency (LDHF) training. Booster training is used when the learner is still proficient, but competency begins to wane. Booster training occurs less frequently than maintenance training but with greater intensity to overcome the skill decay that occurs over time. Refresher training is aimed at re-establishing skill levels after competency has reached unsatisfactory levels. Refresher training is higher intensity than booster and maintenance training. We describe simulation-based strategies reported in the literature that can be used for each type of training. We conclude that there should be an increased emphasis in medical education towards maintenance and booster training in order to preserve skills before competency is lost.