Cerebrospinal Fluid Leak Presenting as Headache: A Case Report.

Headache is a common chief complaint among patients. When presented with this chief complaint, clinicians often form a differential diagnosis of common etiologies, including dehydration, increased stressors, and medication side effects. However, a skillful clinician must always be vigilant of rare etiologies presenting with common chief complaints.

Subversion of T lineage commitment by PU.1 in a clonal cell line system.

Specification of mammalian T lymphocytes involves prolonged developmental plasticity even after lineage-specific gene expression begins. Expression of transcription factor PU.1 may maintain some myeloid-like developmental alternatives until commitment.

Lineage plasticity and commitment in T-cell development.

The earliest stages of intrathymic T-cell development include not only the acquisition of T-cell characteristics but also programmed loss of potentials for B, natural killer, and dendritic cell development. Evidence from genetics and cell-transfer studies suggests an order and some components of the mechanisms involved in loss of these options, but some of the interpretations conflict. The conflicts can be resolved by a view that postulates overlapping windows of developmental opportunity and individual mechanisms regulating progression along each pathway.

Definition of regulatory network elements for T cell development by perturbation analysis with PU.1 and GATA-3.

PU.1 and GATA-3 are transcription factors that are required for development of T cell progenitors from the earliest stages. Neither one is a simple positive regulator for T lineage specification, however.

Constitutive expression of PU.1 in fetal hematopoietic progenitors blocks T cell development at the pro-T cell stage.

The essential hematopoietic transcription factor PU.1 is expressed in multipotent thymic precursors but downregulated during T lineage commitment. The significance of PU.