Working memory predicts semantic comprehension in dichotic listening in older adults.

Older adults have difficulty understanding spoken language in the presence of competing voices. Everyday social situations involving multiple simultaneous talkers may become increasingly challenging in later life due to changes in the ability to focus attention. This study examined whether individual differences in cognitive function predict older adults' ability to access sentence-level meanings in competing speech using a dichotic priming paradigm. Older listeners showed faster responses to words that matched the meaning of spoken sentences presented to the left or right ear, relative to a neutral baseline. However, older adults were more vulnerable than younger adults to interference from competing speech when the competing signal was presented to the right ear. This pattern of performance was strongly correlated with a non-auditory working memory measure, suggesting that cognitive factors play a key role in semantic comprehension in competing speech in healthy aging.

Potential of real-time measurement of GFP-fusion proteins.

Building on the basic design concepts of Randers-Eichhorn [Biotechnol. Bioeng. 55 (1997) 921], an on-line, real-time robust, steam sterilisable optical sensor for monitoring green fluorescent protein (GFP) has been developed. A general cloning vector for fusion expression proteins was constructed, allowing expression of both GFP and the target protein as a fusion. Cultivations were carried out at the 20l scale with the signal from the sensor being relayed directly to the control system of the bioreactors. The production of GFP was then measured on-line, the signal was interfaced directly with other controlling parameters, thereby allowing the microbial process to be controlled directly based on recombinant protein expression. A positive expression correlation between on-line and off-line data was obtained. Protein accretion measured off-line was quantified using both LC-MS and plate reader assays. The potential of such a sensor for many aspects of process development is considerable and we have developed a working system which allows the optimisation of production conditions, for example, linking pH control directly to the fusion protein. Results are also presented that illustrate GFP does not alter the cultivation characteristics of the target protein when compared to the native construct. Whether GFP expressed as a fusion influences the solubility of the target protein is also discussed.