How accurate do structures of the β 2 adrenergic receptor (β 2 AR) need to be to effectively serve as platforms for docking-based virtual screening campaigns? To answer this research question, here we targeted through controlled virtual screening experiments 23 homology models of the β 2 AR endowed with different levels of structural accuracy. Subsequently, we studied the correlation between virtual screening performance and structural accuracy of the targeted models. Moreover, we studied the correlation between virtual screening performance and template/target receptor sequence identity. Our study demonstrates that docking-based virtual screening campaigns targeting homology models of the β 2 AR, in the majority of the cases, yielded results that exceeded random expectations in terms of area under the receiver operating characteristic curve (ROC AUC). Moreover, with the most effective scoring method, over one third and one quarter of the models yielded results that exceeded random expectation also in terms of enrichment factors (EF1, EF5, and EF10) and BEDROC (α = 160.9), respectively. Not surprisingly, we found a detectable linear correlation between virtual screening performance and structural accuracy of the ligandbinding cavity. We also found a detectable linear correlation between virtual screening performance and structural accuracy of the second extracellular loop (EL2). Finally, our data indicate that, although there is no detectable linear correlation between virtual screening performance and template/β 2 AR sequence identity, models built on the basis of templates that show high sequence identity with the β 2 AR, especially within the ligand-biding cavity, performed consistently well. Conversely, models with lower sequence identity displayed performance levels

BACKGROUND: A furcate placental cord insertion is rare and potentially dangerous. Prenatal diagnosis of this finding has been reported on only two prior occasions. CASE: We present the case of a 33-year-old patient who, at 35 weeks of gestation, was suspected on ultrasonography to have a cord insertion that was both furcate and velamentous. Because of this finding, the patient underwent labor induction at 37 weeks of gestation and delivered a vigorous neonate vaginally. Pathologic evaluation confirmed furcate placenta. CONCLUSION: The identification of a furcate placenta, a potentially lethal umbilical cord insertion site abnormality, is possible prenatally. Future research should elucidate the prevalence of furcate cord insertions as well as whether they impose increased fetal risk.