Spatio-temporal dynamics of replication and transcription sites in the mammalian cell nucleus.

To study when and where active genes replicated in early S phase are transcribed, a series of pulse-chase experiments are performed to label replicating chromatin domains (RS) in early S phase and subsequently transcription sites (TS) after chase periods of 0 to 24 h. Surprisingly, transcription activity throughout these chase periods did not show significant colocalization with early RS chromatin domains. Application of novel image segmentation and proximity algorithms, however, revealed close proximity of TS with the labeled chromatin domains independent of chase time. In addition, RNA polymerase II was highly proximal and showed significant colocalization with both TS and the chromatin domains. Based on these findings, we propose that chromatin activated for transcription dynamically unfolds or "loops out" of early RS chromatin domains where it can interact with RNA polymerase II and other components of the transcriptional machinery. Our results further suggest that the early RS chromatin domains are transcribing genes throughout the cell cycle and that multiple chromatin domains are organized around the same transcription factory.

Topiramate and adrenocorticotropic hormone (ACTH) as initial treatment for infantile spasms.

Historically, adrenocorticotropic hormone was used as a first-line treatment for infantile spasms; however, there has been increasing use of topiramate as initial therapy. Here, we report a retrospective study of adrenocorticotropic hormone (ACTH) and topiramate as initial treatment for infantile spasms. The neurology patient database at the Children's Hospital of Philadelphia was searched using the International Classification of Diseases, Ninth Revision code for infantile spasms, and 50 patients were randomly chosen for chart review. We identified 31 patients receiving either adrenocorticotropic hormone or topiramate monotherapy (adrenocorticotropic hormone n = 12, topiramate n = 19) as a first-line treatment for infantile spasms. A total of 26 patients were symptomatic and 5 cryptogenic. Six patients treated with adrenocorticotropic hormone had resolution of clinical spasms and hypsarrhythmia within a month, but 3 relapsed. Of the 19 patients treated with topiramate, 4 patients eventually, though over a period of 0, 1, 8, or 69 months, had resolution of spasms and hypsarrhythmia.