Living systems use biological nanomotors to build life's essential molecules--such as DNA and proteins--as well as to transport cargo inside cells with both spatial and temporal precision. Each motor is highly specialized and carries out a distinct function within the cell. Some have even evolved sophisticated mechanisms to ensure quality control during nanomanufacturing processes, whether to correct errors in biosynthesis or to detect and permit the repair of damaged transport highways. In general, these nanomotors consume chemical energy in order to undergo a series of shape changes that let them interact sequentially with other molecules. Here we review some of the many tasks that biomotors perform and analyse their underlying design principles from an engineering perspective. We also discuss experiments and strategies to integrate biomotors into synthetic environments for applications such as sensing, transport and assembly.

Background The pathophysiology of hypertension in the immediate postpartum period is unclear. Methods and Results We studied 988 consecutive women admitted to a tertiary medical center for cesarean section of a singleton pregnancy. Angiogenic factors, soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PlGF), both biomarkers associated with preeclampsia, were measured on antepartum blood samples. We then performed multivariable analyses to determine factors associated with the risk of developing postpartum hypertension. Of the 988 women, 184 women (18.6%) developed postpartum hypertension. 77 out of 184 women developed de novo hypertension in the postpartum period and the remainder had a hypertensive disorder of pregnancy in the antepartum period. A higher body mass index and history of diabetes mellitus were associated with development of postpartum hypertension. The antepartum sFlt1/PlGF ratio positively correlated with blood pressures in the postpartum period [highest postpartum systolic (r=0.29; P<0.001) and diastolic (r=0.28, P<0.001)]. Moreover, the highest tertile of the antepartum sFlt1/PlGF ratio was independently associated with postpartum hypertension [OR: 2.25 (1.19, 4.25), P=0.01 in the de novo hypertensive group and 2.61 (1.12, 6.05) in the persistent hypertensive group; P=0.02] in multivariable analysis. Women developing postpartum hypertension had longer hospitalization than those who remained normotensive (6.5 ± 3.5 versus 5.7 ± 3.4 days; P<0.001). Conclusions Hypertension in the postpartum period is relatively common and is associated with prolonged hospitalization. Women with postpartum hypertension share similar clinical risk factors as well as a similar antepartum plasma angiogenic profile found in women with preeclampsia. These data suggest that postpartum hypertension may represent a group of women with subclinical or unresolved preeclampsia.

Coumarins have attracted intense interest in recent years because they have been identified from natural sources, especially green plants and have diverse pharmacological properties. In this study, we investigated whether 7,8-dihydroxy-4-methylcoumarin (DHMC) caused apoptosis in A549 human non-small cell lung carcinoma cells (NSCLC) and, if so, by what mechanisms. Here, we show that, in A549 human NSCLC cells, DHMC induces apoptosis through mitochondria-mediated caspase-dependent pathway. Although an increase in the levels of reactive oxygen species (ROS) was observed, pre-treatment with antioxidant showed no protective effect against DHMC-induced apoptosis. In addition, our immunoblot data revealed that DHMC treatment led to down-regulation of Bcl-xl, Bax, p21, Cox-2, p53 and upregulation of c-Myc. Results in the present study for the first time suggest that DHMC induces apoptosis in human lung A549 cells through partial inhibition of ERK/ MAPK signaling.