DEAD-box proteins (DBPs) are required in gene expression to facilitate changes to ribonucleoprotein complexes, but the cellular mechanisms and regulation of DBPs are not fully defined. Gle1 is a multifunctional regulator of DBPs with roles in mRNA export and translation. In translation, Gle1 modulates Ded1, a DBP required for initiation. However, overexpression causes defects, suggesting that Ded1 can promote or repress translation in different contexts. Here we show that expression suppresses the repressive effects of , and Gle1 counteracts Ded1 in translation assays Furthermore, Ded1 and Gle1 both affect assembly of pre-initiation complexes. Through mutation analysis and binding assays, we show that Gle1 inhibits Ded1 by reducing its affinity for RNA. Our results are consistent with a model wherein active Ded1 promotes translation, but inactive or excess Ded1 leads to translation repression. Gle1 can inhibit either role of Ded1, positioning it as a gatekeeper to optimize Ded1 activity to the appropriate level for translation. This study suggests a paradigm for finely controlling the activity of DEAD-box proteins to optimize their function in RNA-based processes. It also positions the versatile regulator Gle1 as a potential node for the coordination of different steps of gene expression.

A critical requirement for cell survival after trauma is sealing of breaks in the cell membrane [M. Bier, S.M. Hammer, D.J. Canaday, R.C Lee, Kinetics of sealing for transient electropores in isolated mammalian skeletal muscle cells, Bioelectromagnetics 20 (1999) 194-201; R.C. Lee, D.C. Gaylor, D. Bhatt, D.A. Israel, Role of cell membrane rupture in the pathogenesis of electrical trauma, J. Surg. Res. 44 (1988) 709-719; R.C. Lee, J.F. Burke, E.G. Cravalho (Eds.), Electrical Trauma: The Pathophysiology, Manifestations, and Clinical Management, Cambridge University Press, 1992; B.I. Tropea, R.C. Lee, Thermal injury kinetics in electrical trauma, J. Biomech. Engr. 114 (1992) 241-250; F. Despa, D.P. Orgill, J. Newalder, R.C Lee, The relative thermal stability of tissue macromolecules and cellular structure in burn injury, Burns 31 (2005) 568-577; T.A. Block, J.N. Aarsvold, K.L. Matthews II, R.A. Mintzer, L.P. River, M. Capelli-Schellpfeffer, R.L. Wollman, S. Tripathi, C.T. Chen, R.C. Lee, The 1995 Lindberg Award. Nonthermally mediated muscle injury and necrosis in electrical trauma, J. Burn Care and Rehabil. 16 (1995) 581-588; K. Miyake, P.L. McNeil, Mechanical injury and repair of cells, Crit. Care Med. 31 (2003) S496-S501; R.C. Lee, L.P. River, F.S. Pan, R.L. Wollmann, Surfactant-induced sealing of electropermeabilized skeletal muscle membranes in vivo, Proc. Natl. Acad. Sci. 89 (1992) 4524-4528; J.D. Marks, C.Y. Pan, T. Bushell, W. Cromie, R.C. Lee, Amphiphilic, tri-block copolymers provide potent membrane-targeted neuroprotection, FASEB J. 15 (2001) 1107-1109; B. Greenebaum, K. Blossfield, J. Hannig, C.S. Carrillo, M.A. Beckett, R.R. Weichselbaum, R.C. Lee, Poloxamer 188 prevents acute necrosis of adult skeletal muscle cells following high-dose irradiation, Burns 30 (2004) 539-547; G. Serbest, J. Horwitz, K. Barbee, The effect of poloxamer-188 on neuronal cell recovery from mechanical injury, J. Neurotrauma 22 (2005) 119-132]. The triblock copolymer surfactant Poloxamer 188 (P188) is known to increase the cell survival after membrane electroporation [R.C. Lee, L.P. River, F.S. Pan, R.L. Wollmann, Surfactant-induced sealing of electropermeabilized skeletal muscle membranes in vivo, Proc. Natl. Acad. Sci. 89 (1992) 4524-4528; Z. Ababneh, H. Beloeil, C.B. Berde, G. Gambarota, S.E. Maier, R.V. Mulkern, Biexponential parametrization of T2 and diffusion decay curves in a rat muscle edema model: Decay curve components and water compartments, Magn. Reson. Med. 54 (2005) 524-531]. Here, we use a rat hind-limb model of electroporation injury to determine if the intravenous administration of P188 improves the recovery of the muscle function. Rat hind-limbs received a sequence of either 0, 3, 6, 9, or 12 electrical current pulses (2 A, 4 ms duration, 10 s duty cycle). Magnetic resonance imaging (MRI) analysis, muscle water content and compound muscle action potential (CMAP) amplitudes were compared. Electroporation injury manifested edema formation and depression of the CMAP amplitudes. P188 (one bolus of 1 mg/ml of blood) w...

Quantitative subtractively normalized interfacial Fourier transform infrared reflection spectroscopy (SNIFTIRS) was used to determine the conformation and orientation of sodium dodecyl sulfate (SDS) molecules adsorbed at the single crystal Au(111) surface. The SDS molecules form a hemimicellar/hemicylindrical (phase I) structure for the range of potentials between -200 ≤ E < 450 mV and condensed (phase II) film for electrode potentials ≥500 mV vs Ag/AgCl. The SNIFTIRS measurements indicate that the alkyl chains within the two adsorbed states of SDS film are in the liquid-crystalline state rather than the gel state. However, the sulfate headgroup is in an oriented state in phase I and is disordered in phase II. The newly acquired SNIFTIR spectroscopy measurements were coupled with previous electrochemical, atomic force microscopy, and neutron reflectivity data to improve the current existing models of the SDS film adsorbed on the Au(111) surface. The IR data support the existence of a hemicylindrical film for SDS molecules adsorbed at the Au(111) surface in phase I and suggest that the structure of the condensed film in phase II can be more accurately modeled by a disordered bilayer.

Measurements of drug concentration in cerebrospinal fluid (CSF) provide the most accessible index of drug delivery to the brain. Our perception of the blood-brain barrier has been largely shaped by these measurements. A crucial question for the interpretation of these data is the nature of the relationships between drug concentration in CSF and the drug concentration profile in brain tissue. A distributed model for the delivery of drugs via plasma to brain tissue and CSF is presented, and the relationships between capillary exchange, tissue diffusion, and CSF turnover rate are explored. The effects of blood-brain barrier disruption on tissue and CSF concentrations are also simulated.

Hydrophilic poly(ethylene glycol) diacrylate (PEGDA) hydrogel surfaces resist protein adsorption and are generally thought to be unsuitable for anchorage dependent cells to adhere. Intriguingly, our previous findings revealed that PEGDA superporous hydrogel scaffolds (SPHs) allow anchorage of bone marrow derived human mesenchymal stem cells (hMSCs) and support their long term survival. Therefore, we hypothesized that the physicochemical characteristics of the scaffold impart properties that could foster cellular responses. We examined if hMSCs alter their microenvironment to allow cell attachment by synthesizing their own extracellular matrix (ECM) proteins. Immunofluorescence staining revealed extensive expression of collagen type I, collagen type IV, laminin and fibronectin within hMSC-seeded SPHs by the end of the third week. Whether cultured in serum-free or serum-supplemented medium, hMSC ECM protein gene expression patterns exhibited no substantial changes. The presence of serum proteins is required for initial anchorage of hMSCs within the SPHs but not for the hMSC survival after 24 hours. In contrast to 2D expansion on tissue culture plastic (TCP), hMSCs cultured within SPHs proliferate similarly in the presence or absence of serum. To test whether hMSCs retain their undifferentiated state within the SPHs, cell-seeded constructs were cultured for 3 weeks in stem cell maintenance medium and the expression of hMSC-specific cell surface markers were evaluated by flow cytometry. CD105, CD90, CD73 and CD44 were present to a similar extent in the SPH and in 2D monolayer culture. We further demonstrated multi lineage potential of hMSCs grown in the PEGDA SPHs whereby differentiation into osteoblasts, chondrocytes and adipocytes could be induced. The present study demonstrates the potential of hMSCs to alter the “blank” PEGDA environment to a milieu conducive to cell growth and multi-lineage differentiation by secreting adhesive ECM proteins within the porous network of the SPH scaffolds.

Controlling the microscale environment in three-dimensional (3D) matrices for tissue engineering applications is a challenging but necessary goal. In this work, the effect of discrete microscale structures (microrods) on cell proliferation was assessed in 3D gels. Microrods were fabricated out of SU-8 with dimensions of 100 x 15 x 15 microm (L x H x W) and incorporated into Matrigel seeded with fibroblasts. The 3D microrod-Matrigel composite system inhibited proliferation of both primary and cell-line fibroblasts compared to cells seeded in Matrigel alone. To rule out bulk mechanical effects, the bulk shear modulus (G') and loss modulus (G") were assessed between 0.1 and 5 Hz for both Matrigel and microrod-Matrigel composites. The incorporation of microrods did not change the bulk stiffness of the gel. Moreover, it was determined that the chemistry of the microrod material itself did not inhibit cell proliferation. Therefore, results indicate that the presence of suspended microscale structures in three dimensions can regulate cell proliferation in a dose-dependent manner. This system provides a biocompatible, long-term way to modulate cell growth in 3D cultures and is amenable to in vivo applications.

Certain transmitters inhibit Kir3 (GIRK) channels, resulting in neuronal excitation. We analysed signalling mechanisms for substance P (SP)-induced Kir3 inhibition in relation to the role of phosphatidylinositol 4,5-bisphosphate (PIP 2 ). SP rapidly -with a half-time of ∼10 s with intracellular GTPγS and ∼14 s with intracellular GTP -inhibits a robustly activated Kir3.

Objective: To investigate airway morphology changes in patients with Pierre Robin sequence (PRS) pre–/post–mandibular distraction osteogenesis (MDO) and to compare morphologic changes to age-matched controls. Design: Retrospective case–control study. Setting: Urban, academic, tertiary medical center. Patients, Participants: Fifteen patients with PRS after MDO to relieve upper airway obstruction (UAO) (2008-2018); age-matched controls for post-MDO patients. Interventions: Mandibular distraction osteogenesis, curvilinear internal mandibular distractors. Main Outcome Measures: (1) Physiologic improvement after MDO (apnea–hypopnea index; minimum oxygen saturation); (2) airway size (volume, surface area, length, mean/minimum cross-sectional area), shape (lateral:anterior–posterior ratio, cross-sectional area ratios, uniformity, sphericity), and changes with MDO; and (3) post-MDO airway size, shape versus age-matched controls. Results: Airway size increased after MDO (volume, P = .01; surface area, P = .02; length, P = .01), as did cross-sectional area (mean, P = .02; minimum, P = .02; minimum retropalatal, P = .05, mid-retroglossal, P = .02). Post-MDO PRS airways were larger than controls (volume, P < .01; surface area, P < .01; length, P < .01, cross-sectional area, P = .03). Airway shape remained nonuniform and flat post-MDO; control airways were round. Two syndromic patients required repeat MDO and had subphysiologic post-MDO airway cross-sectional area. Post-MDO PRS patients with supraphysiologic cross-sectional area along the entire airway had no UAO recurrence. Conclusions: In this small, heterogenous patient sample, MDO increases airway size, may preferentially affect the retropalatal airway, and often results in supraphysiologic airway dimensions. These retropalatal changes may be important in relieving severe UAO in patients with PRS. Generalizability of our results is limited by small cohort size and patient heterogeneity.