Prdm1 (Blimp-1) and the Expression of Fast and Slow Myosin Heavy Chain Isoforms during Avian Myogenesis In Vitro

BACKGROUND. Multiple types of fast and slow skeletal muscle fibers form during early embryogenesis in vertebrates. In zebrafish, formation of the earliest slow myofibers in fin muscles requires expression of the zinc-finger transcriptional repressor Prdm1 (also known as Blimp1). To further understand how the role of Prdm1 in early myogenesis may vary through evolution and during development, we have now analyzed Prdm1 expression in the diverse types of myotubes that form in culture from somitic, embryonic, and fetal chicken myoblasts. PRINCIPAL FINDINGS. In cultures of somitic, embryonic limb, and fetal limb chicken cells, we found that Prdm1 was expressed in all of the differentiated muscle cells that formed, including those that expressed only fast myosin heavy chain isoforms, as well as those that co-expressed both fast and slow myosin heavy chain isoforms. Prdm1 was also expressed in Pax7-positive myoblasts, as well as in non-myogenic cells in the cultures. Furthermore, though all differentiated cells in control somite cultures co-expressed fast and slow myosin heavy chains, antisense knockdown of Prdm1 expression inhibited the formation of these co-expressing cells in somite cultures. CONCLUSIONS. In chicken myogenic cell cultures, Prdm1 was expressed in most Pax7-positive myoblasts and in all differentiated muscle cells, irrespective of the developmental stage of cell donor or the pattern of fast and slow myosin heavy chains expressed in the differentiated cells that were formed. Thus, Prdm1 was expressed in myogenic cells prior to terminal differentiation; and, after differentiation, Prdm1 expression was not limited to cells that expressed slow myosin heavy chain isoforms. In addition, Prdm1 appeared to be required for differentiation of the somitic myocytes, which are the earliest myocytes to form in the avian embryo.National Research Initiative of the United States Department of Agriculture Cooperative State Research, Education, and Extension Service (#2006-35206-16622); National Heart, Lung, and Blood Institute (2R01HL064641

Feasibility of performing apnea test in a brain dead patient on veno-venous extracorporeal membrane oxygenation (ECMO)

Extracorporeal membrane oxygenation (ECMO) is being increasingly used to provide support in patients with refractory cardiopulmonary distress syndromes. Neurological sequelae, either from the ECMO or the hypoxic/hypotensive event leading to ECMO, are common. We present a patient requiring veno-venous (V-V) ECMO for an acute respiratory distress syndrome (ARDS) following cardiopulmonary arrest who suffered an irreversible brain injury. Eventually she required an evaluation for death by neurological criteria while on V-V ECMO making apnea testing challenging. We report the ability to safely perform apnea testing in a patient with a devastating brain injury requiring V-V ECMO.Includes bibliographical reference

Adenovirus-mediated hPNPase(old-35) gene transfer as a therapeutic strategy for neuroblastoma

Current treatment options for neuroblastoma fail to eradicate the disease in the majority of high-risk patients, clearly mandating development of innovative therapeutic strategies. Gene therapy represents a promising approach for reversing the neoplastic phenotype or driving tumor cells to self-destruction. We presently studied the effects of adenovirus-mediated gene transfer of human polynucleotide phosphorylase (hPNPase(old-35)), a 3',5'-exoribonuclease with growth-inhibitory properties, in neuroblastoma cells. Transgene expression was driven by either the cytomegalovirus (CMV) promoter or by a tumor-selective promoter derived from progression elevated gene-3 (PEG-3). Our data demonstrate that efficient adenoviral transduction of neuroblastoma cells and robust transgene expression are feasible objectives, that the PEG-3 promoter is capable of selectively targeting gene expression in the majority of neuroblastoma cells, and that hPNPase(old-35) induces profound growth suppression and apoptosis of malignant neuroblastoma cells, while exerting limited effects on normal neural crest-derived melanocytes. These findings support future applications of hPNPase(old-35) for targeted gene-based therapy of neuroblastoma and suggest that combination with the PEG-3 promoter holds promise for creating a potent and selective neuroblastoma therapeutic