China 
Africa 
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Active Nanoparticle Targeting: Current Status and Future Challenges
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Siddharth Patel, Janni Mirosevich
The way in which targeting moieties/ligands on nanoparticles can potentially adversely affect cell biology is another essential factor when evaluating targeted delivery systems. The melanocortin 1 receptor (MC1R) belongs to a family of five G protein-coupled melanocortin receptors (MC1R–MC5R) and is highly expressed on the surface of melanomas (Rosenkranz et al. 2013). As such, a number of highly specific and selective ligands against MC1R have been developed (Cai et al. 2006; Mayorov et al. 2006; Koikov et al. 2003). These ligands have been used for targeted imaging agents, targeted polymer-based micelles, and polymeric gene delivery nanoparticles (Durymanov et al. 2012; Barkey et al. 2011; Tafreshi et al. 2012; Barkey et al. 2013). However, MC1R activation is known to be involved in proliferation of melanoma cells (Rosenkranz et al. 2013). It is also known that EGF binding to EGFR activates signaling pathways that stimulate cell proliferation and survival (Master and Sen Gupta 2012; Wang 2012). Therefore, because many ligands are known to activate signaling pathways that promote cancer growth, downstream molecular pathways must be considered in order to ensure that nanoparticle ligand binding does not have unfavorable effects on the cells and tissues being treated.
The individual and combined effects of spaceflight radiation and microgravity on biologic systems and functional outcomes
Published in Journal of Environmental Science and Health, Part C, 2021
Jeffrey S. Willey, Richard A. Britten, Elizabeth Blaber, Candice G.T. Tahimic, Jeffrey Chancellor, Marie Mortreux, Larry D. Sanford, Angela J. Kubik, Michael D. Delp, Xiao Wen Mao
Initiatives to study bone health in space have predominantly focused on how spaceflight negatively impacts skeletal structure and biomechanical properties with the overarching goal of understanding how they contribute to fracture risk. While it is important to address remaining knowledge gaps on fracture risk in follow-up studies, investigations by the space research community also need to broaden to reflect our growing understanding of skeletal function. Beyond providing structural support, the skeleton is an endocrine organ that can crosstalk with other tissues to maintain health and homeostasis. A number of studies demonstrate the ability of bone to function as an endocrine organ (reviewed in 104–106 to regulate a variety of physiological processes including glucose metabolism,107–109 appetite suppression,110 cognition and behavior.111,112 The organism’s ability to coordinate the function of multiple tissues via bone-derived factors is essential to keep up with the demands of daily living. For example, bone-derived lipocalin-2 (LCN2) regulates glucose homeostasis via endocrine action on major metabolic organs, and also can cross the blood-brain barrier to control appetite via its binding to the melanocortin receptor (MC4R) in the hypothalamus.110 In addition, LCN2 can exert pro-inflammatory actions on a variety of cell types including vascular cells.113 Osteocalcin (OCN), another bone-derived hormone can modulate cognition and anxiety-like behavior. 111,112 Mice heterozygous for an OCN null allele showed deficits in cognition while administration of OCN improved memory and decreased anxiety-like behaviors.112 In addition, OCN has been shown to mediate aspects of the acute stress response. In the presence of stressors, it is thought that OCN participates in signaling to inhibit the parasympathetic branch of the autonomic nervous system to allow the sympathetic pathway to predominate, in turn promoting flight or fight responses.114 The biological processes regulated by these bone-derived hormones are critical for human health and performance in space missions. Hence, it is important to begin to address whether combined spaceflight factors can perturb signaling mediated by bone-derived hormones. More studies also are needed to understand the role of bone crosstalk with other organs in mediating the physiological changes attributed to spaceflight.