PubMed Health⌕ Search

Biomedical subjects

D Basilico

Publications and source records attributed to D Basilico.

2 recordsLinked to original sources

Verbs, events and spatial representations.

Are concepts expressed in language also represented spatially? To pursue this question we investigated the structure of events. Events are defined as actions with spatial trajectories that can be perceived by our senses and described in language. Events are expressed linguistically in sentences containing verbs which determine the thematic roles of the arguments (e.g., who is doing what to whom, where). Because of previous observations we focused on whether events are represented spatially by location of thematic roles and direction of actions. Location and direction were dissociated by contrasting different kinds of verbs: 'push' vs 'pull' in which actions move toward or away from the agent. To control for spatial effects produced by the surface structure of a left to right written language, we kept the structure of sentences constant and sought for spatial biases produced by differences in the meaning of these sentences. From three experiments using drawing and sentence-picture matching reaction time tasks, we found that normal subjects located agents to the left of patients and represented actions with a left to right directionality. These results are not easily explained by features of the surface structure of language or properties of propositional representations. We suggest that events have spatial representations in addition to their propositional counterparts of verbs and thematic roles. The specific spatial properties observed may relate to functional properties of the left hemisphere.

Adolescent↗

Isolation of large numbers of enriched human megakaryocytes from liquid cultures of normal peripheral blood progenitor cells.

Investigations linking human megakaryocyte development and cell biology have been hindered by an inability to obtain large, relatively pure megakaryocyte cell preparations from in vitro stem cell cultures. We report here that such preparations can be generated from liquid cultures of normal human peripheral blood mononuclear cells stimulated by a serum source of megakaryocyte colony stimulating activity (Meg-CSA, the 0% to 60% ammonium sulfate protein fraction of aplastic canine serum). Adherent-depleted peripheral blood mononuclear cells are suspended at 5 x 10(5) to 10(6) cells/mL in supplemented liquid culture medium, platelet-poor human plasma 20% (vol/vol) and 1 to 2 mg/mL serum Meg-CSA protein. After 12 to 14 days of incubation, megakaryocytes constitute 3.0 +/- 2.9% (mean +/- SD, n = 8) of the unseparated cultured cell population. Megakaryocytes can be enriched by counterflow centrifugal elutriation to a purity of 58 +/- 14% (+/- SD) with a recovery of 13 +/- 7% and a viability of 67 +/- 19%. This algorithm results in the average isolation of approximately 3 x 10(5) enriched megakaryocytes from a 100-mL starting volume of peripheral blood. Cultured megakaryocytes exhibit normal light and ultrastructural morphology by Wright-Giemsa staining and electron microscopic analysis. After a 12-day culture interval, enriched megakaryocyte preparations exhibit morphologic stage distributions that are similar to normal human marrow. Stage distributions move rightward with culture duration indicating partial synchrony of megakaryocyte maturation. On cytospin preparations, megakaryocyte diameter averages 30.2 +/- 1.5 microns and increases with maturation stage. Flow cytometric analyses demonstrate the expression of platelet glycoproteins (GP) Ib and IIb/IIIa by the cultured megakaryocytes. The modal ploidy of the enriched cells at day 12 of culture is 16N and most remaining megakaryocytes are 8N or 32N. Liquid culture of serum Meg-CSA-stimulated human peripheral blood mononuclear cells represents a valuable investigative tool that should permit studies of human megakaryocyte biology that have not been possible in the past.

Algorithms↗