The polyamines putrescine, spermidine, and spermine have been implicated in the regulation of both proliferation and differentiation. Spermidine is required for DNA replication, and the intracellular depletion of this polyamine can be used to distinguish cellular events related to proliferation. We have demonstrated previously that depletion of intracellular spermidine results in cytostasis of ...

Neuroblastomas arc histopathologically heterogeneous, ranging from immature malignant tumors to benign ganglioneuromas. The amount of Schwann cell stroma greatly increases with neuroblastoma differentiation, and these Schwann cells appear to be normal cells that infiltrate the tumor. To determine whether Schwann cells influence neuroblast differ entiation, four human neuroblastoma cell lines we...

Experiments were designed to study development of bovine embryos in TCM-199 medium conditioned by preculture with buffalo rat liver (BRL) cells. Conditioned media were harvested after BRL cells were cultured until confluency (CON), or for an additional 2 d with the same cells but new medium (CON-N) or the same medium (CON-S). Glucose in TCM-199 was depleted by BRL cells to different concentrati...