The Factor Structure of Vocabulary: An Investigation of Breadth and Depth of Adults with Low Literacy Skills.

The purpose of this study was to examine the factor structure of vocabulary. We believe that not only is vocabulary multidimensional, but depth of vocabulary knowledge should also be assessed with multiple measures since it too, is composed of multiple aspects. Furthermore, to explore the predictive validity of the different aspects of vocabulary knowledge, we assessed the relationship between vocabulary breadth, vocabulary depth, and reading comprehension in adults with low literacy skills. The participants were 103 adults. They completed 12 tasks that have been used in past studies to measure vocabulary breadth, depth, and reading comprehension. We had several important findings. First, we confirmed that all of the assessments were highly reliable for adults with low literacy skills. Second, the results of the factor analysis indicated two distinct vocabulary factors. Finally, both breadth and depth contribute independently to explaining variance in reading comprehension. Implications for vocabulary measurement are suggested.

Increased susceptibility of breast cancer cells to stress mediated inhibition of protein synthesis.

Protein synthesis is a tightly controlled process, and its deregulation plays an important role in tumorigenesis. Protein synthesis remains poorly understood with very few well-identified validated targets for therapeutic purposes. In this study, we use nitric oxide (NO), which suppresses protein synthesis by inactivating eukaryotic initiation factor 2-alpha (eIF2-alpha), to examine the mechanism by which low and high oxidative stress inhibits protein synthesis. In breast cancer cells, low NO stress induced heme-regulated inhibitor (HRI) activation, which facilitated gradual decline in short half-life proteins. High NO stress induced HRI and protein kinase R (PKR) activation, leading to a sharp decline in protein synthesis as accessed by a decline in short and long half-life proteins and dramatic morphologic changes. In contrast, human mammary epithelial (HME) and Ras transfected untransformed HME (MCF-10A1 neo N) cells were less susceptible to NO-induced inhibition of protein synthesis and cytostasis. Our results suggest that NO-induced cytostasis in breast cancer cells was due to PKR activation and increased phosphorylation of eIF2-alpha, whereas the reduced susceptibility of normal mammary epithelial cells to NO could be due to the inaccessibility of PKR, which is bound to inhibitor p58.