Cynthia C. Morton

The implementation of universal screening programs to detect hearing defects in newborns has dramatically increased the identification of hearing loss in infants. Recent advances in understanding the nature and causes of prelingual hearing loss, combined with advances in technology, suggest that further improvement in these programs can readily be achieved.

The consistent appearance of specific chromosomal translocations in human Burkitt lymphomas and murine plasmacytomas has suggested that these translocations might play a role in malignant transformation. Here we show that transformation of these cells is frequently accompanied by the somatic rearrangement of a cellular analogue of an avian retrovirus transforming gene, c-myc. Moreover, we map c-myc to human chromosome 8 band q24, the chromosomal segment involved in the reciprocal Burkitt translocations [t(8;14), t(8;22) and t(2;8)]. In two t(8;14) human Burkitt cell lines, c-myc appears to have been translocated directly into a DNA restriction fragment that also encodes the immunoglobulin mu chain gene. In the case of a specific cloned fragment of DNA derived from a mouse plasmacytoma, we demonstrate directly that c-myc has been translocated into the immunoglobulin alpha switch region. Our data provide a molecular basis for considering the role that specific translocations might play in malignant transformation.

Embryonic stem cells have the unique ability to form all adult cell types. Harnessing this potential may provide a source of cells to replace those that are lost or impaired as a result of disease. Moreover, the derivation of human embryonic stem cells opens a unique window into the study of early human development. At present, approximately 15 human embryonic stem-cell lines are publicly available, and they vary considerably in their usefulness for research and the extent of their characterization (see http://stemcells.nih.gov/registry/index.asp). To promote further research with human embryonic stem cells, we sought to derive and characterize more fully cell lines that meet strict criteria for ease of manipulation, including enzymatic passage with trypsin, streamlined freezing and thawing procedures, well-defined culture mediums, and straightforward methods for in vitro differentiation. We report the derivation and characterization of 17 additional human embryonic stem cell lines.