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Activating Transcription Factor 5 (ATF5) recently has been demonstrated to play a critical role in promoting the survival of human glioblastoma cells. Interference with the function of ATF5 in an in vivo rat model caused glioma cell death in primary tumors but did not affect the status of normal cells surrounding the tumor, suggesting ATF5 may prove an ideal target for anti-cancer therapy. In order to examine ATF5 as a pharmaceutical target, the protein must be produced and purified to sufficient quantity to begin analyses. Here, a procedure for expressing and refolding the bZIP domain of ATF5 in sufficient yield and final concentration to permit assay development and structural characterization of this target using solution NMR is reported. Two-dimensional NMR and circular dichrosim analyses indicate the protein exists in the partially α-helical, monomeric x-form conformation with only a small fraction of ATF5 participating in formation of higher-order structure, presumably coiled-coil homodimerization. Despite the persistence of monomers in solution even at high concentration, an electrophoretic mobility shift assay showed that ATF5 is able to bind to the cAMP response element (CRE) DNA motif. Polyacrylamide gel electrophoresis and mass spectrometry were used to confirm that ATF5 can participate in homodimer formation and that this dimerization is mediated by disulfide bond formation. KeywordsATF5; ATFx; bZIP; recombinant expression; protein refolding; disulfide bond Activating Transcription Factor 5 (ATF5) recently has been recognized for its importance in neurological development and contribution to brain cancer. This protein functions to maintain the cell in a proliferative state and must be down regulated in order for differentiation to occur in neural progenitor cells [1][2][3]. While ATF5 is highly expressed in developing neurons, it is not expressed to any detectable level in healthy mature neural tissue [1,3]. Increased levels of ATF5 have, however, been observed in primary brain tumors, and expression is elevated to particularly high levels in human glioblastoma [4]. It also is overproduced in several human and rat glioma cell lines [4]. The absence of ATF5 expression in mature neurons and its prominence in brain tumors has made it an appealing target for anti-cancer therapy. Importantly, an in vivo rat model has demonstrated that interference with ATF5 function caused glioma cell death in primary tumors, while it did not affect the status of normal cells surrounding the tumor [4]. This data suggests ATF5 is a prime target for pharmaceutical intervention.1 The University of Kansas, Department of Pharmaceutical Chemistry, Multidisciplinary Research Building, 2030 Becker Dr. Lawrence, KS 66047, Phone: (785) Fax: (785) 864-5736, E-mail: laurencj@ku.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typeset...

The objective of this study is to establish new reference ranges for whole blood electrolytes, gases, and selected chemistries in normal healthy newborn infants obtained from cord blood and at 2-4 hours of life based on modern analytic techniques. Healthy appropriate-for-gestational age (AGA), term infants were studied. Whole venous cord blood and blood drawn at 2-4 hours of life were analyzed for gases, sodium, potassium, chloride, ionized calcium, ionized magnesium, hemoglobin, and hematocrit. Concentrations for blood glucose and blood urea nitrogen were close to older published concentrations. Na(+), K(+), and Cl(-) were significantly different and had much narrower normal margins. New norms are included for blood gases, lactate, iCa, and iMg. We offer a range of values for often-measured blood chemistries in term, healthy infants, using modern laboratory methods. These values could serve as more up-to-date references compared with older values found in major textbooks of Neonatology.

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Vortex ring collisions have attracted intense interest in both water and air studies (Baird in Proc R Soc Lond Ser Math Phys Sci 409:59–65, 1987, Poudel et al. in Phys Fluids 33:096105, 2021, Lim and Nickels in Nature 357:225, 1992, New et al. in Exp Fluids 57:109, 2016, Suzuki et al. in Geophys Res Lett 34, 2007, Yan et al. in J Fluids Eng 140:054502, 2018, New et al. in J Fluid Mech 899, 2020, Cheng et al. in Phys Fluids 31:067107, 2019, Hernández and Reyes in 29:103604, 2017, Mishra et al. in Phys Rev Fluids, 2021, Zednikova et al. in Chem Eng Technol 42:843–850, 2019, Kwon et al. in Nature 600:64–69, 2021). These toroidal structures spin around a central axis and travel in the original direction of impulse while spinning around the core until inertial forces become predominant causing the vortex flow to spontaneously decay to turbulence (Vortex Rings, https://projects.iq.harvard.edu/smrlab/vortex-rings). Previous studies have shown the collision of subsonic vortex rings resulting in reconnected vortex rings, but the production of a shock wave from the collision has not been demonstrated visibly (Lim and Nickels in Nature 357:225, 1992, Cheng et al. in Phys Fluids 31:067107, 2019). Here we present the formation of a shock wave due to the collision of explosively formed subsonic vortex rings. As the vortex rings travel at Mach 0.66 toward the collision point, they begin to trap high pressure air between them. Upon collision, high pressure air was imploded and released radially away from the axis of the collision, generating a visible shock wave traveling through and away from the colliding vortices at Mach 1.22. Our results demonstrate a pressure gradient with high pressure release creating a shock wave. We anticipate our study to be a starting point for more explosively formed vortex collisions. For example, explosives with different velocities of detonation could be tested to produce vortex rings of varying velocities.