Biomedical subjects

S M McCrea

Publications and source records attributed to S M McCrea.

3 recordsLinked to original sources

PubMed2002

A case study of strategic infarct dementia investigated with the cognitive assessment system.

Two subjects with brain lesions who were matched on demographic variables were tested on the Cognitive Assessment System (CAS). AK had been dependent on caregivers after a frontal aneurysm 6 years previously despite intact receptive and expressive language skills and motor functions. GM sustained multiple infarcts although he continued to function well on his own. Nonparametric analysis showed that AK's T scores on CAS subtests were lower than that of GM's based on a comparison with a heterogeneous group of brain-damaged patients (p < .003). The CAS's broad range of complexity of items within subtests, apparent sensitivity in differentiating rates of cognitive decline in dementia, and convergence with dementia rating scales suggests that it could be useful for assessment of strategic infarct dementia.

Cerebral Infarction↗

PubMed1999

Quantitative analyses of schooling effects on executive function in young children.

Developmental studies have demonstrated the utility of select executive function (EF) tasks for the early diagnosis of specific learning-related problems (e.g., Snow, 1998). However, previous data demonstrating schooling effects on EF measures suggests potential pitfalls in clinical interpretation. In the present study three common EF measures, (Wisconsin Card Sort, Thurstone Word Fluency, and a mazes task) in addition to a VIQ estimating task, were administered to a cross-section of 115 children aged 7 to 9. Using a school-entrance cut-off design the unique contributions of formal schooling versus age-related changes to performance on the EF measures were examined. Schooling effects were both task and age-dependent supporting the conclusion that the proper use of EF measures with children in this age range depends upon consideration of factors beyond that usually depicted in net-effect models.

Age Factors↗

PubMed1987

Selective removal of the carboxyl-terminal tail end of the Dictyostelium myosin II heavy chain by chymotrypsin.

Dictyostelium myosin II is a conventional myosin consisting of two heavy chains of 243,000 Da and two pairs of light chains of 16,000 and 18,000 Da. In this paper, we show that the heavy chain of myosin II can be rapidly and selectively cleaved by chymotrypsin to yield two fragments with molecular weights of 195,000 and 38,000 Da as estimated from sodium dodecyl sulfate-polyacrylamide gels. Chymotryptic cleavage at this site occurs most readily in the absence of salt and is greatly inhibited as the salt concentration is increased from 0 to 60 mM. Amino acid sequence analysis of the small fragment demonstrates that its amino terminus corresponds to lysine 1826 of the myosin II heavy chain. If the fragment extends to the carboxyl terminus of the myosin II heavy chain, it would have a molecular weight of 33,700. Upon digestion of myosin II which has been phosphorylated with a high molecular weight Dictyostelium myosin heavy chain kinase (Côté, G.P., and Bukiejko, U. (1987) J. Biol. Chem. 262, 1065-1072), all of the phosphate is recovered on the 33,700-Da tail-end fragment. Chymotrypsin-cleaved myosin II is shown to be capable of forming filaments at salt concentrations between 20 and 100 mM as judged by its ability to be sedimented by centrifugation. Only the large fragment of myosin II is found in the pellet; the 33,700-dalton fragment remains soluble. Chymotrypsin-cleaved myosin II can bind to actin and displays a high Ca2+-activated ATPase activity but has very low actin-activated ATPase activity.

Actins↗