Highly specific separation of heterogeneous cell populations by lectin-coated beads: application for the isolation of inner medullary collecting duct cells.

Conditions for the highly specific selection of a cell type by the use of lectin-coated magnetic beads are reported for the isolation of inner medullary collecting duct (IMCD) cells from a heterogeneous inner medullary cell suspension, containing both single cells and tubular fragments of variable size. The lectin Dolichos Biflorus Agglutinin (DBA), which binds in rat inner medulla exclusively to IMCD cells, was coupled via the avidin-biotin system to beads. By isolating DBA-bead-IMCD cells in a magnetic field (positive selection) from a suspension containing about 50% IMCD, a fraction of 98 +/- 1% purity was obtained; recovery of cells was up to 90%. Suspensions negative on reverse-transcriptase polymerase chain reaction for vimentin as a marker of contaminating interstitial and vascular cells could be received by repeating this procedure and additional trypsinization. On the other hand, it was possible to reduce the portion of IMCD cells in the suspension by one isolation step to 1.5 +/- 0.9% (negative selection). Performing this step twice resulted in virtually pure suspensions. No significant effects of this isolation technique on cell viability, growth characteristics, and biochemical parameters were observed. Therefore, this method appears to be a powerful tool for the highly specific separation of heterogeneous cell populations.

Relation between mental age and vocabulary development among children with mild mental retardation.

An investigation of the relation between lexical knowledge and mental age (MA) in elementary school-age children with mild mental retardation was conducted. Lexical knowledge was assessed using the Peabody Picture Vocabulary Test-Revised (PPVT-R) and the Boehm Test of Basic Concepts. Items on the PPVT-R focus on labels for objects and events; items on the Boehm focus on relational terms. Mental age was measured via the Columbia Mental Maturity Scale. Results indicated that the relation between lexical knowledge and MA depended upon the nature of the vocabulary test: The correlation between the Boehm and MA was significantly higher than that between the PPVT-R and MA, suggesting that for this population, MA is more strongly related to knowledge of abstract relational terms than to knowledge of labels for objects and events. The latter may be more open to the influence of differential language experience.