No abstract

No abstract

Strain rate imaging is a new modality in echocardiography intended for analysis of left ventricular function. This modality extends ultrasonographic techniques for analysis of tissue velocities by providing information about rates of local myocardial compression and expansion. Cyclic cardiac deformation is a complex process. Precision and accuracy of real-time strain rate (rtSR) measurements have not been studied under controlled laboratory conditions. Using a cyclically compressed tissue-mimicking gelatin phantom, we compared rtSR values to corresponding strain rate values calculated off line from local tissue velocities measured by Doppler echocardiography. We tested a clinically relevant range of strain rates (0.5 - 3.5 sec(-1)) and different angles of insonation. Initial tests showed high precision (r > or = 0.973, P < 0.001), but the assessment of accuracy (bias < or = 0.559 sec(-1)) suggested a trend toward systematic underestimation of the reference values. We suspected a confounding influence of a clutter filter and repeated the tests with the filter inactive. The resulting accuracy improved tenfold (bias < or = 0.045 sec(-1)), and the systematic underestimation was no longer present. We conclude that the rtSR is precise and accurate for a range of the tested values.

HuR is a ubiquitously expressed AU-rich element (ARE)-binding protein that interacts with and stabilizes selective early response gene (ERG) mRNAs after cell activation or stress. To date, approximately 20 mRNAs have been unambiguously defined as HuR ligands. Given the discordance between the large number of ERG mRNAs and those few defined as ligands, we applied in vitro selection to isolate a broad range of HuR mRNA ligands using postseizure mouse hippocampal tissue. Selected mRNAs were converted into cDNA libraries and sequenced. Using this approach, we have identified over 600 novel, putative HuR mRNA ligands. These genes code for a variety of proteins, including transcription factors, signaling molecules, and kinases, but many have unknown function. Consistent with the means of their selection, several of these HuR ligands are differentially expressed in hippocampus after seizure. These results demonstrate a biochemical approach to identify and characterize the diverse repertoire of ligands for HuR and other regulatory mRNA-binding proteins.