Sensitivity and Specificity of a Nurse Dysphagia Screen in Stroke Patients.

PURPOSE: To determine how well an institutionally developed nurse dysphagia screening tool correctly identified the presence (sensitivity) or absence (specificity) of dysphagia in patients following acute stroke. METHODS: A method-comparison design was used to compare results of the Nurse Dysphagia Screen to the dysphagia evaluation by a speech and language pathologist (SLP). Each newly diagnosed participant served as his or her control, with both dysphagia evaluations (nurse, SLP) occurring within 2 hours of each other. Sensitivity and specificity of the Nurse Dysphagia Screen was calculated using standard formulas. RESULTS: For 49 patients evaluated following stroke, average age was 71.7 (SD +/- 13.5). Twenty-five subjects were female and 24 were male. The majority of the participants had strokes identified as ischemic in origin (n=35). The SLP found 18 (37%) participants had a positive dysphagia assessment. The Nurse Dysphagia Screen was positive in 16 of 18 participants screened positive by SLP, resulting in some type of dietary restriction. The Nurse Dysphagia Screen was negative in 28 of the 31 patients screened as negative by SLP. Sensitivity and specificity of the Nurse Dysphagia Screen were 89% and 90%, respectively. CONCLUSIONS: An easy-to-use, institutionally developed nurse dysphagia screening tool successfully identified patients with swallowing difficulties after stroke later diagnosed by SLP.

Functional analysis of a tripartite stability element within the CD40 ligand 3' untranslated region.

We previously identified a cis-acting element within the 3' untranslated region of CD40 ligand messenger RNA (mRNA) that is composed of three complex binding sites and acts to increase mRNA stability in both in vitro and in vivo systems. We now demonstrate the functional consequences of the three binding sites with respect to increasing both luciferase activity and mRNA stability in a heterologous transcript expressed in a T-cell line. The internal region B was shown to be a bona fide stability element because its presence increased luciferase activity fourfold over the unmodified transcript and its removal from the XbaI-HaeIII region resulted in rapid degradation of the transcript. Region A contained both a binding site for a polypyrimidine-tract-binding protein (PTB)-mediated complex (Complex I) and an upstream, adjacent sequence that was a negative regulator of mRNA stability. Region C bound Complex II, which contained both PTB and heterogeneous nuclear ribonucleoproteinL (hnRNPL), and was less effective as a stability element on its own compared to region B. Our findings demonstrate differential levels of activity for the three binding sites relative to the turnover of CD40 ligand mRNA, suggesting that the lack of binding of Complex I/II during the early stages of T-cell activation contributes to the rapid degradation of the CD40 ligand mRNA transcript.

Nucleolin is a second component of the CD154 mRNA stability complex that regulates mRNA turnover in activated T cells.

CD154 (CD40L) mRNA turnover is regulated in part at the posttranscriptional level by a protein complex (termed Complex I) that binds to a highly CU-rich region of the 3'UTR. Polypyrimidine tract-binding protein (PTB) has previously been identified as a major RNA-binding protein in Complex I. Nondenaturing gel filtration of total extract from Jurkat T cells demonstrated that the CD154 mRNA-binding activity migrates as a approximately 200-kDa complex, indicating the presence of multiple complex-associated proteins. We have currently undertaken a biochemical approach to further characterize Complex I and observed that it segregates over DEAE-Sepharose into two subcomplexes (termed I-L and I-U). Furthermore, nucleolin was identified as a component of both subcomplexes and was shown that it is the major RNA-binding protein in I-U. To directly demonstrate the biological significance of Complex I binding to the CD154 transcript, cytoplasm from human Jurkat cells was fractionated over a sucrose gradient and the different cellular fractions subjected to immunoprecipitation with anti-PTB and anti-nucleolin Abs. RT-PCR of the immunoprecipitated products using CD154-specific primers clearly demonstrated that nucleolin and PTB are associated with CD154 mRNA in both the ribonucleoprotein and polysome fractions. These data strongly support a model whereby nucleolin and PTB are integral to the stability of CD154 mRNA and are components of the CD154 ribonucleoprotein particle associated with actively translating ribosomes.

A complex containing polypyrimidine tract-binding protein is involved in regulating the stability of CD40 ligand (CD154) mRNA.

CD40 ligand (CD154) expression has been shown to be regulated, in part, at the posttranscriptional level by a pathway of "regulated instability" of mRNA decay throughout a time course of T cell activation. This pathway is modulated at late times of activation by the binding of a stability complex (termed complex I) to a CU-rich region in the 3' untranslated region of the CD154 message. We have undertaken experiments to extend these findings and to analyze the cis-acting elements and trans-acting factors involved in this regulation. We have previously shown that the minimal binding sequence for complex I is a 63 nt CU-rich motif. However, our current study shows that when this site was deleted additional complex binding was observed upstream and downstream of the minimal binding region. Only after deletion of an extended region (termed Delta1515) was complex binding completely abolished. Analysis of complex binding using competition experiments revealed that the three adjacent regions bound related but not identical complexes. However, all three sites appeared to have a 55-kDa protein as the RNA-binding protein. Deletion of the Delta1515 region resulted in reduced transcript stability as measured by both in vitro and in vivo decay assays. Finally, using Abs against known RNA-binding proteins, we identified the polypyrimidine tract-binding protein (or heterogeneous nuclear ribonucleoprotein I) as a candidate RNA-binding component of complex I.