Leah Marks

Villous Explant Culture: Characterization and Evaluation of a Model to Study Trophoblast Invasion

The mechanisms that control invasion of cytotrophoblast (CTB) cells into the maternal decidua and myometrium with transformation of the maternal spiral arteries are not fully understood, but oxygen is thought to be a key factor. We carried out a semiquantitative evaluation of an explant culture model for use in the study of trophoblast proliferation and invasion. Explants of human villous tissue (6–9 weeks of gestation) cultured on Matrigel in both standard culture conditions (18% O2) and in a low oxygen environment (2% O2) produced regions of outgrowth, of cytotrophoblast cells from villous tips and migration of cells into the Matrigel. The number of sites of outgrowth and migration, area of outgrowth, and extent of migration of cells into the Matrigel tended to increase throughout the culture period (144 h) but varied between explants from the same placenta and those from different placentas. There were no significant differences in the number of sites of outgrowth or migration scores in explants cultured in a low oxygen environment compared to those cultured in standard conditions. This study highlights the importance of careful validation, design and interpretation of experiments using in vitro culture systems, particularly those investigating the regulatory role of oxygen.

Is peer review an appropriate form of assessment in a MOOC? Student participation and performance in formative peer review

Abstract Many aspects of higher education must be reconceptualised for massive open online courses (MOOCs). Formative and summative assessment of qualitative work in particular requires novel approaches to cope with the numbers involved. Peer review has been proposed as one solution, and has been widely adopted by major MOOC providers, but there is currently little evidence about whether it is appropriate or under what conditions. Here, we examine student participation, performance and opinions of a peer review task in a biomedical science MOOC. We evaluate data from approximately 200 student topic summaries and 300 qualitative peer reviews of those summaries, and compare these to student demographic data (gender, age, employment status, education, national language) and to performance in multiple choice tests. We show that higher performance in the written topic summary correlated with both higher participation in the peer review task and with writing higher quality peer reviews. Qualitative analysis of student comments revealed that student opinion on the usefulness of the peer review task was mixed: some strongly believed it benefitted their learning, while others did not find it useful or did not participate. We suggest instructional design strategies to improve student participation and increase learning gain from peer review in the MOOC context.

Endothelial activation and cell adhesion molecule concentrations in pregnant women living at high altitude.

Objectives: Maternal physiology at high altitude could be considered to resemble an intermediate state between preeclampsia and normal pregnancy. The objective of the current study was to determine if cell adhesion molecules, known to be increased in preeclampsia, are increased with chronic maternal and placental hypoxia (due to high-altitude residence) in the absence of preeclampsia. Methods: Serum was collected from women residing at 3100 m or 1600 m in the three trimesters of pregnancy and postpartum. Vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and intercellular adhesion molecule-1 (ICAM-1) were measured by enzyme-linked immunosorbent assay (ELISA). Results: General linear model (GLM) repeated measures analysis of VCAM-1, E-selectin, and ICAM-1 data showed there were no statistically signiciant effects of gestation within either the high- or moderate-altitude groups or between the different altitude. Conclusion: The increase in cell adhesion molecules reported in preeclampsia is not present in pregnant women at high altitude, suggesting that maternal systemic hypoxia is not responsible for this pathway of endothelial cell activation in preeclampsia.

Improving the Effectiveness of Feedback by Use of Assessed Reflections and Withholding of Grades.

We wished to improve levels of student engagement with feedback within the context of our postgraduate masters-level programme, and therefore evaluated the use of two interventions: assessed reflections on feedback and grade-withholding. In questionnaires students reported more engagement with feedback after the interventions, with 77% in favour of using reflections, though only 57% favoured grade-withholding, with feelings of frustration and anxiety about the grade cited as factors. Overall class grades improved over the two years in which reflections were used, with the greatest gains made by students generating the most insightful reflections. Additional gains in the second year of intervention may have been attributable to improved implementation or the introduction of grade-withholding, or a combination of both. Overall we demonstrated clear improvement in feedback utilisation and achievement associated with our interventions.

Student experience of peer assessment on an MSc programme

Abstract The validity of peer assessment as well as students experience and understanding of the process are recurrent themes in the educational literature. We studied postgraduates’ experience of summative peer assessment, in particular their perceptions of the process. Student experience was generally positive, and not affected by characteristics such as first language (English or not), area of origin (European Union versus international), previous degree (medical versus science), or current academic performance in the MSc class. Several key themes emerged and are discussed further with possible implications for both practice and future research.

Endothelial activation and E-selectin concentrations in the maternal circulation of high altitude pregnancies

WithdrawnCONTEXT 9alpha,11beta-Prostaglandin F(2) (9alpha,11beta-PGF(2)) can contract uterine smooth muscle with a potency equal to PGF(2alpha). Its presence in the human uterus and production by human gestational tissues is unknown. OBJECTIVE These studies were performed to determine whether the PGD(2)-derived 9alpha,11beta-PGF(2) is both present in human amniotic fluid and synthesized by human gestational tissues and if so, whether labor-related substances could regulate its production. RESULTS Detectable concentrations of 9alpha,11beta-PGF(2) were found in amniotic fluid samples and appeared to increase in late gestation. All gestational tissues studied synthesized 9alpha,11beta-PGF(2), with the placenta having the highest basal production rate, followed by the amnion and then the choriodecidua. IL-1beta and TNFalpha caused concentration-dependent increases in 9alpha,11beta-PGF(2) production in human amnion and choriodecidual explants. Moreover, treatment of choriodecidual and placental explants with lipopolysaccharide resulted in a significant increase in 9alpha,11beta-PGF(2) production rates, reaching a maximum of 13-fold in the choriodecidua. Studies examining the effects of the addition of exogenous PGD(2) strongly indicated that the choriodecidua has significant ability to convert PGD(2) to 9alpha,11beta-PGF(2), whereas the amnion has little. CONCLUSIONS These results demonstrate for the first time that 9alpha,11beta-PGF(2) is present in human amniotic fluid and that it is produced by human gestational tissues and up-regulated by bacterial cell wall components and proinflammatory cytokines. We suggest that this prostaglandin may play a part in the mechanisms of human labor at term and preterm.