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R Zacks

Publications and source records attributed to R Zacks.

7 recordsLinked to original sources
PubMed1998

Inhibition of intrathymic T cell development by expression of a transgenic antagonist peptide.

The mature T cell receptor (TCR) repertoire is shaped by positive- and negative-selection events taking place during T cell development. These events are regulated by interactions between the TCR and major histocompatibility complex molecules presenting self-peptides. It has been shown that many antagonist peptides are efficient at mediating positive selection. In this study we analyzed the effects of a transgene encoding an antagonist peptide (influenza NP34) that is presented by H-2Db in a Tap-1-independent fashion in mice expressing the influenza NP68-specific TCR F5. We find that the transgenic peptide does not mediate positive or negative selection in F5(+)Tap-1(-/-) mice, but inhibits maturation of CD8(+) single positive thymocytes in F5(+)Tap-1(+) mice without inducing signs of negative selection. We conclude that antagonism of antigen recognition occurs not only at the level of mature T cells but also in T cell development.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Cognitive gerontology and attentional inhibition: a reply to Burke and McDowd.

Our response to the Burke and McDowd critiques (in this issue) begins with a history of the origins of the inhibitory deficit view and of its development since 1988 as well as with an account of some particularly useful findings and of our preferred mode of theory building, which is nonformal and empirically driven. Against this background, we find many points of agreement with Burke and McDowd but also many points of disagreement. For example, we agree with Burke that many aspects of language comprehension and production are age invariant, but we disagree that all such findings count against our viewpoint. Likewise, we readily acknowledge the problems in measuring inhibition that McDowd so clearly documents, but do not feel that this is a fatal problem as long as the inhibitory deficit view continues to be viable within the basic attentional literature, continues to permit the integration of a large body of existing data, and continues to generate new predictions.

Aged↗
PubMed1984

The structure of medical knowledge in the memories of medical students and general practitioners: categories and prototypes.

According to recent research on categorization, knowledge of a given category is structured in memory around key cases or clear examples, referred to as the prototypes, which capture the core meaning of the category. The purpose of this study was to establish a converging sequence of evidence concerning the internal structure of fourteen broad categories of medical disorders as stored in the long-term memories of pre-clinical medical students and experienced doctors. It was shown that the mental representation of the categories was better described by the overlapping features of the prototype view of categorization than the criterial features of the classical view. It is argued that the prototype view may help facilitate the understanding of the learning and problem-solving process in medicine.

Humans↗