RESUMEN
Neuropathies of the lower extremity may occur from traumatic injury, surgery, tumor, entrapment by adjacent structures, and a variety of other causes. At times, the clinical presentation can be confusing. Because of its superior soft tissue contrast and the ability to image in any plane, MR imaging is the modality of choice for visualization of peripheral nerve pathology. This article discusses the anatomy and pathology of the nerves of the leg, ankle, and foot, with an emphasis on MR imaging.
Asunto(s)
Tobillo/inervación , Pie/inervación , Pierna/inervación , Imagen por Resonancia Magnética/métodos , Enfermedades del Sistema Nervioso Periférico/diagnóstico , Diagnóstico Diferencial , Humanos , Nervios Periféricos/anatomía & histología , Nervios Periféricos/patología , Enfermedades del Sistema Nervioso Periférico/patologíaRESUMEN
The yeast PHO2 gene encodes a homeodomain protein that exemplifies combinatorial control in transcriptional activation. Pho2 alone binds DNA in vitro with low affinity, but in vivo it activates transcription with at least three disparate DNA-binding proteins: the zinc finger protein Swi5, the helix-loop-helix factor Pho4, and Bas1, an myb-like activator. Pho2 + Swi5 activates HO, Pho2 + Pho4 activates PHO5, and Pho2 + Bas1 activates genes in the purine and histidine biosynthesis pathways. We have conducted a genetic screen and identified 23 single amino acid substitutions in Pho2 that differentially affect its ability to activate its specific target genes. Analysis of the mutations suggests that the central portion of Pho2 serves as protein-protein interactive surface, with a requirement for distinct amino acids for each partner protein.