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Biomedical subjects

R L Michael

Publications and source records attributed to R L Michael.

5 recordsLinked to original sources
PubMed1996

Prenylation of oncogenic human PTP(CAAX) protein tyrosine phosphatases.

Many isoprenylated proteins are known to participate in signal transduction, but not all have been identified. Using an in vitro prenylation screen, two human cDNAs (PTP(CAAXI) and PTP(CAAX2)) homologous to the rat PRL-1 and human OV-1 protein tyrosine phosphatase genes were identified. PTP(CAAXI) and PTP(CAAX2) were farnesylated in vitro by mammalian farnesyl:protein transferase, and epitope-tagged PTP(CAAX2) was prenylated in epithelial cells. Overexpression of PTP(CAAXI) and PTP(CAAX2) in epithelial cells caused a transformed phenotype in culture and tumor growth in nude mice. Thus, PTP(CAAXI) and PTP(CAAX2) represent a novel class of isoprenylated, oncogenic protein tyrosine phosphatases.

Alkyl and Aryl Transferases↗
PubMed1991

Transient effects of acquisition history on generalization in a matching-to-sample task.

This study examined the role of learning history on the acquisition of a matching-to-sample task. Twelve preschool children learned four stimulus classes through instructions, shaping, or imitation. After reaching criterion, the subjects were exposed to changed discrimination contingencies to determine how each learning history affected the acquisition of responses appropriate to the new contingencies. All subjects reached criterion on the new relations, although the subjects with a shaping history adapted slightly more quickly than those subjects with a history of instructions or imitation. Given sufficient exposure to changed contingencies, rule-driven insensitivity to contingencies was overcome by experience with consequences. This result may be specific to younger subjects, but it suggests that instructions can be used in education without creating insensitivity to contingencies.

Attention↗
PubMed1990

The utility of verbal and behavioral assessments of value.

Subjects lived in a laboratory apartment for up to 30 days, engaging in ordinary activities such as reading, sewing, and artwork. The amount of time devoted to each activity was recorded and compared with periodic verbal ratings of the amount of time devoted to the activities. The verbal and observational assessments of the time distribution were very similar, but there were some discrepancies. Based on self-reports and on observation of time actually devoted to the activities, contingencies were arranged in which time devoted to one activity produced time available for a second activity. When the contingency relation was based on behavioral assessment, predictions of time redistribution were more accurate than when the relations were based on verbal assessment. The close correspondence between observed distributions of time and verbally assessed distributions was probably due to the well-specified situation and rigorous assessment methods. Contrary to some cognitive-behavioral accounts, the contingency results suggest that verbal assessment is not necessarily preferable to observation when the two make discrepant predictions. It is suggested that verbal reports might be used more often in behavior analysis in place of lengthy or difficult observations, and attention is drawn to a personality model that parallels important components of behavior analysis.

Adolescent↗
PubMed1981

Learning-disordered children's evoked potentials during sustained attention.

Evoked potentials and performance of 19 learning-disordered (LD) and 19 normally achieving children were studied in two versions of the Continuous Performance Test (CPT). In both CPT procedures, LD children made more errors of omission and commission than did normal children. Evoked potential differences between groups were especially prominent in the more difficult BX version of the CPT. LD children displayed significantly smaller late positive components (LPC) of the evoked potential to critical stimuli in the task. There were no LPC differences between diagnostic groups for noncritical stimulus categories. The results suggest a deficit in behavioral and cortical indices of sustained attention among LD children.

Adolescent↗