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Maternofetal Stress Impairs Skeletal Muscle Growth and Glucose Metabolism in the IUGR-Born Neonatal Lamb; The Effects of Varying the Cognitive Processes Required by Retrieval Practice on the Retention of Knowledge
Our first study sought to identify if intermittent maternofetal oxygen supplementation (IUGR+O2) during late gestation rescued growth and skeletal muscle glucose metabolism impaired by hyperthermia-induced intrauterine growth restriction (IUGR) in lambs. Birthweight, bodyweight (BW), and brain:BW was less in IUGR lambs but did not differ between IUGR+O2 and controls. Glucose-stimulated insulin secretion (GSIS) tended to be lower in IUGR lambs but was recovered by IUGR+O2. Insulin stimulated glucose oxidation rates in hindlimb tissues of lambs and in primary skeletal muscle at necropsy were decreased by IUGR but rescued in IUGR+O2 lambs. However, hindlimb and ex vivo skeletal muscle glucose uptake did not differ among groups. These data show that fetal hypoxemia drives the development of IUGR and metabolic deficiencies but that intermittent maternofetal oxygen supplementation improves skeletal muscle growth and glucose metabolism. To evaluate inflammatory factors involved in adaptive fetal programming, we developed a maternofetal inflammation-induced IUGR (MI-IUGR) model. For this study, we evaluated the effects of sustained maternal inflammation on fetal inflammation, growth, and skeletal muscle glucose metabolism. Near-term fetuses demonstrated elevated circulating leukocytes and ~22% reduction in size 2 weeks after induction of inflammation ceased. Fetal inflammation impaired muscle glucose metabolism; in vivo and ex vivo insulin-stimulated glucose oxidation was reduced in MI-IUGR fetuses. In vivo glucose uptake did not differ, but ex vivo uptake was reduced under basal and insulin-stimulated conditions. Thus, maternofetal inflammation resulted in an IUGR phenotype characterized by adaptive fetal growth restriction and impaired skeletal muscle glucose metabolism. Lastly, we performed a study to determine the effects of retrieval practices in the form of homework assignments requiring higher-order cognitive skills (HOC) compared to those requiring lower-order cognitive skills (LOC) on students’ long-term retention of knowledge. There were no differences in short-term or long-term knowledge retention between retrieval practice types. However, students completing HOC retrieval practices had decreased performance scores for 9 of 11 topics. Retrieval practices create desirable difficulties that benefit knowledge retention, but only when an equal degree of success is achieved. These data indicate that desirable difficulties were not created, as students were not equally successful on both types of retrieval practices.
Cadaret, Caitlin N, "Maternofetal Stress Impairs Skeletal Muscle Growth and Glucose Metabolism in the IUGR-Born Neonatal Lamb; The Effects of Varying the Cognitive Processes Required by Retrieval Practice on the Retention of Knowledge" (2019). ETD collection for University of Nebraska-Lincoln. AAI27543937.