C C Dow | PubMed Health

PubMed2001

Object naming and semantic knowledge in temporal lobe epilepsy.

Object-naming impairment is common among temporal lobe epilepsy (TLE) patients, but other aspects of semantic memory have received limited attention in this population. This study examined object-naming ability and depth of semantic knowledge in healthy controls (n = 29) and patients with early onset TLE (n = 21). After administration of the Boston Naming Test (BNT), the authors asked participants to provide detailed definitions of 6 BNT objects. The TLE group demonstrated a significant deficit relative to controls in both object-naming ability and semantic knowledge for the target objects, even after controlling for IQ. In a multiple regression analysis that included other neuropsychological test scores as independent variables, the semantic knowledge score was the only significant predictor of patients' object-naming performance. Thus, at the group level, early onset TLE patients have a semantic knowledge deficit that contributes to dysnomia.

Adolescent↗

PubMed2000

Correlation between the chaperone-like activity and aggregate size of alpha-crystallin with increasing temperature.

alpha-Crystallin, the major protein of the mammalian eye lens, is also found in the major tissues of the body, where one or the other of its two isoforms is characteristically expressed. Both isoform sequences are highly related to others of the small heat shock protein superfamily, leading to speculation about their functions in vivo outside of the lens. Tests of chaperone-like activity at 37 and 66 degrees C indicate that the protein can act to prevent the superaggregation of partially denatured proteins, but both alpha-crystallin aggregate size and shape are significantly altered with increasing temperature. Characterization of these changes indicates that secondary, tertiary, and quaternary structure are modified, with the latter effect especially striking above 50 degrees C. Furthermore, these changes appear to be irreversible when the temperature is returned to 25 or 37 degrees C. Functionally, the protein is effective in chaperone-like activity at all temperatures, but exhibits a somewhat increased capability after a cycle of heating and cooling. The results presented here indicate the heat-induced formation of high-molecular-weight aggregates of alpha-crystallin is a slow progressive process. The increased activity of these aggregates suggests that chaperone-like activity depends in part on the packing parameters of the aggregate and on conformation of the subunit within that aggregate.

Animals↗