Tatsuya Takizawa

MRNA expression of molecules related to the activity of nitric oxide or prostaglandin E2, the critical regulators maintaining the ductus arteriosus patency, was examined in rat ductus arteriosus at preterm (days 18.5 and 19.5 of pregnancy) and near term (days 20.5 and 21.5). The endothelial nitric oxide synthase mRNA level increased transiently at preterm and then decreased at near term. The cyclooxygenase 2 mRNA increased gradually from near-term to the term complementary to the reduced endothelial nitric oxide synthase mRNA. These results suggest that the role shift between nitric oxide and prostaglandin E2 in maintaining ductus arteriosus patency at preterm and near term may be due to complementary expression changes of endothelial nitric oxide synthase and cyclooxygenase 2 at the transcriptional level.

The involvement of nitric oxide (NO) signaling in apoptosis was examined in the placental bed of mid‐to‐late pregnant rats. Pregnant rats were treated with l‐NAME, a nitric oxide synthase inhibitor, by subcutaneous infusion for 48 hours before the examination at day 13.5, 17.5, or 21.5. l‐NAME induced apoptosis in the placental bed to a limited extent at days 13.5 and 17.5, but not at day 21.5. When the placental bed was examined at day 17.5, the protein expression of both executioner (C‐Cas3) and inhibitor (XIAP) of apoptosis was increased by l‐NAME, but they did not co‐localized with apoptosis. It was presumed that placental bed apoptosis induced by l‐NAME is regulated through the expression of both executioner and inhibitor, possibly involving protein S‐nitrosylation.

Phase-contrast microscopy is a convenient technique for live-cell observation on the surface of materials with high optical transmittance. Here, we demonstrate a novel technique to observe living cells on the surface of materials with low optical transmittance, such as polytetrafluoroethylene (PTFE), which are widely used in biomaterials for blood-contacting devices. The surface of a cover glass was coated with a thin PTFE layer with sufficient transmittance, thereby enabling the observation of living cells on the PTFE surface with a phase-contrast microscope.