Vascularization on newly implanted metal orthopedic implants has remained a challenge in the field of tissue engineering. To address this challenge, in this research, an interconnected foam structure of Ti-6Al-4V was microfabricated by electron beam melting (EBM) technique. The foam in question has a density of 1.77 g cm −3 with 60% porosity and a tensile strength of 18 GPa. An extracellular matrix based hydrogel was added as an aqueous matrix to the foam. Hypoxia mimetic stress has been closely related to many wound healing biomedical applications as it increases survival and proliferation molecular signals. To that end, increased expression of hypoxia-inducible factor-1α (Hif-1α) and vascular endothelial growth factor (VEGF) in the aqueous hydrogel matrix was achieved by the addition of a hypoxia mimetic deferoxamine mesylate (DFM). In this study, the formation of an endothelial network was achieved in a hydrogel matrix in the presence of the before mentioned 3D printed metal foam. Cellular viability, fluorescent microscopy and scanning electron microscopy imaging analysis demonstrate that pre-osteoblasts undergo proliferation and also attach efficiently to the foam when exposed to DFM. Human umbilical vascular endothelial cells (HUVECs) were grown in an extracellular matrix-like 3D hydrogel and a hypoxia-like stress was achieved. This research demonstrates that pre-osteoblast cells undergo cell differentiation and increase the production of hydroxyapatite on exposure to the hypoxia mimetic molecule. This proposed approach encompasses an ideal prototype for a completely living implanted structure for future orthopedic implants.
This study assessed the role of stress systems in the nucleus accumbens (NAc) in promoting sex differences in the reinforcing effects of nicotine. Intravenous self-administration (IVSA) of various doses of nicotine was compared following overexpression of corticotropin-releasing factor (CRF) in the NAc of female and male rats. Ovariectomized (OVX) females were also included to assess the role of ovarian hormones in promoting nicotine reinforcement. Rats received intra-NAc administration of an adeno-associated vector that overexpressed CRF (AAV2/5-CRF) or green fluorescent protein (AAV2/5-GFP). All rats were then given extended access (23 h/day) to an inactive and an active lever that delivered nicotine. Separate groups of rats received intra-NAc AAV2/5-CRF and saline IVSA. Rats were also allowed to nose-poke for food and water during IVSA testing. At the end of the study, the NAc was dissected and rt-qPCR methods were used to estimate CRF overexpression and changes in CRF receptors (CRFr1, CRFr2) and the CRF receptor internalizing protein, β-arrestin2 (Arrb2). Overexpression of CRF in the NAc increased nicotine IVSA to a larger extent in intact female versus male and OVX females. Food intake was increased to a larger extent in intact and OVX females as compared to males. The increase in CRF gene expression was similar across all groups; however, in females, overexpression of CRF resulted in a larger increase in CRFr1 and CRFr2 relative to males. In males, overexpression of CRF produced a larger increase in Arrb2 than females, suggesting greater CRF receptor internalization. Our results suggest that stress systems in the NAc promote the reinforcing effectiveness of nicotine in female rats in an ovarian hormone-dependent manner.
Abstract:We present the chemical synthesis of hexaniobate nanotubes using two routes, (1) starting material K4Nb6O17 and (2) parent material of H4Nb6O17 via ion exchange. The as-synthesized materials were exfoliated by adjusting the pH to 9-10 using tetra-n-butylammonioum hydroxide (TBA + OH − ), leading to a formation of hexaniobate nanotubes. In order to understand morphology a full characterization was conducted using SEM, HRTEM, BET and powder-XRD. The photocatalytic activity was evaluated using photolysis method using Bromocresol Green (BG) and Methyl Orange (MO) as model contaminants. Results indicate a nanotube porous oxide with large porous and surface area; the photocatalytic activity is about 95% efficient when comparing with commercial TiO2.
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