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Metallic and Non-Metallic Plasmonic Nanostructures for LSPR Sensors
Get PDFLocalized surface plasmonic resonance (LSPR) provides a unique scheme for light management and has been demonstrated across a large variety of metallic nanostructures. More recently, non-metallic nanostructures of two-dimensional atomic materials and heterostructures have emerged as a promising, low-cost alternative in order to generate strong LSPR. In this paper, a review of the recent progress made on non-metallic LSPR nanostructures will be provided in comparison with their metallic counterparts. A few applications in optoelectronics and sensors will be highlighted. In addition, the remaining challenges and future perspectives will be discussed
Subthreshold white noise vibration alters trembling sway in older adults
Get PDFBackground
Somatosensory deficit is a significant contributor to falls in older adults. Stochastic resonance has shown promise in recent studies of somatosensation-based balance disorders, improving many measures of stability both inside and outside of the clinic. However, our understanding of this effect from a physiological perspective is poorly understood. Therefore, the primary goal of this study is to explore the influence of subthreshold vibratory stimulation on sway under the rambling-trembling framework.
Methods
10 Healthy older adults (60–65 years) volunteered to participate in this study. Each participant underwent two randomized testing sessions on separate days, one experimental and one placebo. During each session, the participants' baseline sway was captured during one 90-s quiet standing trial. Their sensation threshold was then captured using a custom vibratory mat and 4–2-1 vibration perception threshold test. Finally, participants completed another 90-s quiet standing trial while the vibratory mat vibrated at 90% of their measured threshold (if experimental) or with the mat off (if placebo). While they completed these trials, an AMTI force plate collected force and moment data in the anteroposterior (AP) and mediolateral (ML), from which the center of pressure (COP), rambling (RM), and trembling (TR) time series were calculated. From each of these time series, range, variability (root-mean-square), and predictability (sample entropy) were extracted. One-tailed paired t-tests were used to compare baseline and during-vibration measures.
Results
No significant differences were found during the placebo session. For the experimental session, significant increases were found in AP TR range, ML TR RMS, AP COP predictability, and AP & ML TR predictability. The TR time series was particularly sensitive to vibration, suggesting a strong influence on peripheral/spinal mechanisms of postural control.
Significance
Though it is unclear whether observed effects are indicative of “improvements” or not, it does suggest that there was a measurable effect of subthreshold vibration on sway. This knowledge should be utilized in future studies of stochastic resonance, potentially acting as a mode of customization, tailoring vibration location, duration, magnitude, and frequency content to achieve the desired effect. One day, this work may aid in our ability to treat somatosensation-based balance deficits, ultimately reducing the incidence and severity of falls in older adults
Identifying the phonological backbone in the mental lexicon
Get PDFPrevious studies used techniques from network science to identify individual nodes and a set of nodes that were “important” in a network of phonological word-forms from English. In the present study we used a network simplification process—known as the backbone—that removed redundant edges to extract a subnetwork of “important” words from the network of phonological word-forms. The backbone procedure removed 68.5% of the edges in the original network to extract a backbone with a giant component containing 6,211 words. We compared psycholinguistic and network measures of the words in the backbone to the words that did not survive the backbone extraction procedure. Words in the backbone occurred more frequently in the language, were shorter in length, were similar to more phonological neighbors, and were closer to other words than words that did not survive the backbone extraction procedure. Words in the backbone of the phonological network might form a “kernel lexicon”—a small but essential set of words that allows one to communicate in a wide-range of situations—and may provide guidance to clinicians and researchers on which words to focus on to facilitate typical development, or to accelerate rehabilitation efforts. The backbone extraction method may also prove useful in other applications of network science to the speech, language, hearing and cognitive sciences
Tailoring the secretome composition of mesenchymal stem cells to augment specific functions of epidermal regeneration: an in vitro diabetic model
Get PDFIntroduction: Wound healing consists of a dynamic series of events that are highly dependent on paracrine factors for proper progression through the phases of wound healing. Inappropriate progression through the phases is associated with insufficient epidermal regeneration (i.e., re-epithelialization) of wounds and subsequent propagation of chronic wounds, such as diabetic ulcers, which are associated with increased patient morbidity. Recently, investigation into the dynamic secretome of Adipose-derived Mesenchymal Stem Cells (ASCs), have shown promise in augmenting the wound healing response of chronic diabetic wounds. However, currently utilized 2D culture techniques are known to drastically alter the regenerative phenotype of ASCs. In this study a novel tissue-mimetic 3D system was utilized as a means to culture ASCs.
Methods: The capacity for the ASC secretome to augment epidermal regeneration activity was then evaluated after exposure of ASCs to “wound priming stimuli” in 2D and 3D. The priming stimuli consisted of coating the 2D and 3D systems with the wound matrix proteins, collagen type I, fibronectin, and fibrin. To understand the potential benefit of the ASC secretome in the context of diabetic wounds, keratinocytes (KCs) were exposed to super-physiological glucose levels to induce a diabetic-like phenotype (idKCs).
Results: Relative to KCs, idKC exhibited a 52% and 23% decline in proliferation and migration, respectively. Subsequently, analyses of the ASC secretome were performed. ASC conditioned media (ASC-CM) from tissue-mimetic culture demonstrated a > 50% increase secretion of proteins and a 2-fold increase in secreted EVs, relative to 2D culture. Interestingly, the different priming stimuli did not alter the total amount of protein or EVs secreted within the tissue-mimetic system. However, evaluation of specific soluble proteins via ELISA revealed significant differences in key epidermal regeneration factors, such as EGF, IGF-1, FGF-2, MMP-1, TIMP-1, and TGFβ-1. Additionally, the relative effect of ASC-EVs from the 2D and 3D system on idKCs epidermal regeneration functionality varied significantly, with EVs from 3D-Collagen culture providing the most significant benefit on idKC activity.
Discussion: Together, these data support the utilization of tissue-mimetic culture system to enhance the adaptability and secretory activity of MSC-like populations in order to generate tailored biologics, via priming stimuli, for specific wound healing applications
“Posts are my own”: effects of social media disclaimers on perceptions of employees and their organizations from tweets and retweets
Get PDFPURPOSE – This study empirically assesses the perceptions the public has of employees and their organization following a [re]tweet, and the additional potential ameliorating effect of a disclaimer distancing the organization from the individual employee’s social media presence.
DESIGN/METHOD/APPROACH – A fully-crossed 2 (disclaimer v. no disclaimer) × 2 (positive v. negative valence post) × 2 (post v. retweet) experiment exposed participants (N = 173) to an employee’s personal tweet. Resultant perceptions of both the poster (i.e., goodwill) and the poster’s organization (i.e., organizational reputation) were analyzed using planned contrast analyses.
FINDINGS – Findings reveal audiences form impressions of individuals based on both tweeted and retweeted content. Perceptions of both the poster’s goodwill and the poster’s organization were commensurate with the valence of the poster’s tweets, stronger when posts were original tweets rather than retweets, and there was a significant interaction effect between valence and [re]tweet. Disclaimers did not significantly affect perceptions, suggesting employers may be better-served by asking employees to omit reference to their employer on their personal social media accounts.
ORIGINALITY/VALUE – This research contributes to understanding how employee and organizational reputations are affected by employees’ personal social media content. Results suggest even when a disclaimer explicitly seeks to distance the employee from the organization, audiences still see the employee as informal brand ambassadors of their organization
ASM History: Presidents/Vice Presidents
Get PDFClinton Hart Merriam (1855–1942), a classically trained medical doctor of the latter 1800s, quit his medical practice in 1885 to follow his lifelong passion of natural history. In 1885, he became the first chief of the Division of Economic Ornithology, which in 1886 was renamed the Division of Economic Ornithology and Mammalogy of the United States Department of Agriculture. The Division later became the U.S. Fish and Wildlife Service in 1940. Because of his leadership there, driving passion for research, and no doubt charismatic personality, in 1919 Merriam was elected as the first president of the newly formed American Society of Mammalogists. Our fledging Society thrived under his leadership, but full credit must also be given to the unselfish, dedicated work in fostering the new Society from the legions of other members. The first listing of members, published in the Journal of Mammalogy in 1920, included 358 individuals from 15 countries. The photograph taken of attendees at the organizational meeting of the Society in 1919 shows 14 women and 43 men (Timm and McLaren 2019). Running the ASM has been a team effort from the beginning, with legions of members serving on committees, working closely with elected officers and other colleagues behind the scenes, and volunteers quietly running much Society business. Anna M. Jackson, wife of Hartley H. T. Jackson, the first Recording Secretary of the ASM and key figure in getting the Society started, is perhaps the earliest example of the importance of the contributions of so many members. In recognition of her time and support, Jackson provided funds for the Anna M. Jackson honorarium to memorialize his wife and to encourage students to attend annual meetings and participate in the Society (Journal of Mammalogy 50:908, 1969). In fact, these involvements provide the background and training instrumental in the development of effective leadership within the ASM throughout our history
Gastrointestinal cell injury and perceived symptoms after running the Boston Marathon
No full textGastrointestinal (GI) disturbances are a prevalent cause of marathon related complaints, and in extreme cases can promote life-threatening conditions such as exertional heat stroke. Our aim was to study intestinal cell injury [via intestinal fatty acid binding protein (I-FABP)] and perceived GI distress symptoms among marathon runners. We also examined potential risk factors (e.g., inadequate sleep) that could exacerbate GI disturbances in healthy, trained endurance runners. This was a parallel mixed-methods study design. 2019 Boston Marathon participants were recruited via email and subjects completed surveys before the race describing demographics and training history. Participants completed a GI questionnaire to assess presence and severity of symptoms, a survey regarding risk factors (e.g., recent illness, medications) that could promote GI disturbances, and provided a urine sample at three time points (immediately pre-race, post-race, and 24-h post-race). Due to weather, blood samples were only collected immediately and 24-h post-race. A total of 40 runners (males: n = 19, age = 44.9 ± 10.8 years; females: n = 21, age = 44.8 ± 10.6 years) completed this study. I-FABP significantly decreased from post-race (3367.5 ± 2633.5 pg/mL) to 24-h post-race (1657.3 ± 950.7 pg/mL, t (39) = −4.228, p < .001, d = −.669). There was a significant difference in overall GI symptom scores across the three time points (F (2, 39) = 41.37, p < .001). The highest average score occurred post-race (.84 ± .68), compared to pre-race (.09 ± .12) and 24-h post-race (.44 ± .28). Post-race I-FABP (r = .31, p = .048) and post-race urine specific gravity (r = .33, p = .041) were significantly correlated with post-race GI symptom scores. Our study provides further support to the individualized nature of GI disturbances, with participants experiencing a wide range of risk factors that can influence the extent of GI damage and perceived symptoms during and after exercise
Quantification and characterization of biological activities of glansreginin A in black walnuts (Juglans nigra)
No full textGlansreginin A has been reported to be an indicator of the quality of walnuts (Juglans spp.). However, bioactive properties of glansreginin A have not been adequately explored. In the present study, we quantified concentrations of glansreginin A in black walnuts (Juglans nigra) using high performance liquid chromatography-tandem mass spectrometry (HPLC–MS/MS) and performed an array of in vitro bioassays to characterize biological activities (e.g., antibacterial, antioxidant, anticancer capacities) of this compound. Results from HPLC–MS/MS analysis indicated that glansreginin A was presented in all 12 black cultivars examined and its contents were variable among black walnut cultivars, ranged from 6.8 mg/kg (Jackson) to 47.0 mg/kg (Hay). Glansreginin A possessed moderate antibacterial activities against Gram-positive pathogens (Staphylococcus aureus and Bacillus anthracis). This compound exhibited no antioxidant activities, did not induce the activity of antioxidant response element signaling pathways, and exerted no antiproliferative effects on tumorigenic alveolar epithelial cells and non-tumorigenic lung fibroblast cells
Mitochondrial Interaction with Serotonin in Neurobiology and Its Implication in Alzheimer’s Disease
No full textAlzheimer’s disease (AD) is a lethal neurodegenerative disorder characterized by severe brain pathologies and progressive cognitive decline. While the exact cause of this disease remains unknown, emerging evidence suggests that dysregulation of neurotransmitters contributes to the development of AD pathology and symptoms. Serotonin, a critical neurotransmitter in the brain, plays a pivotal role in regulating various brain processes and is implicated in neurological and psychiatric disorders, including AD. Recent studies have shed light on the interplay between mitochondrial function and serotonin regulation in brain physiology. In AD, there is a deficiency of serotonin, along with impairments in mitochondrial function, particularly in serotoninergic neurons. Additionally, altered activity of mitochondrial enzymes, such as monoamine oxidase, may contribute to serotonin dysregulation in AD. Understanding the intricate relationship between mitochondria and serotonin provides valuable insights into the underlying mechanisms of AD and identifies potential therapeutic targets to restore serotonin homeostasis and alleviate AD symptoms. This review summarizes the recent advancements in unraveling the connection between brain mitochondria and serotonin, emphasizing their significance in AD pathogenesis and underscoring the importance of further research in this area. Elucidating the role of mitochondria in serotonin dysfunction will promote the development of therapeutic strategies for the treatment and prevention of this neurodegenerative disorder
Gastrointestinal Delivery of an mRNA Vaccine Using Immunostimulatory Polymeric Nanoparticles.
No full textmRNA vaccines can be translated into protein antigens, in vivo, to effectively induce humoral and cellular immunity against these proteins. While current mRNA vaccines have generated potent immune responses, the need for ultracold storage conditions (- 80 °C) and healthcare professionals to administer the vaccine through the parenteral route has somewhat limited their distribution in rural areas and developing countries. Overcoming these challenges stands to transform future deployment of mRNA vaccines. In this study, we developed an mRNA vaccine that can trigger a systemic immune response through administration via the gastrointestinal (GI) tract and is stable at 4 °C. A library of cationic branched poly(β-amino ester) (PBAE) polymers was synthesized and characterized, from which a polymer with high intracellular mRNA delivery efficiency and immune stimulation capacity was down-selected. mRNA vaccines made with the lead polymer-elicited cellular and humoral immunity in mice. Furthermore, lyophilization conditions of the formulation were optimized to enable storage under refrigeration. Our results suggest that PBAE nanoparticles are potent mRNA delivery platforms that can elicit B cell and T cell activation, including antigen-specific cellular and humoral responses. This system can serve as an easily administrable, potent oral mRNA vaccine