Impact of Surface Ligand on the Biocompatibility of InP/ZnS Quantum Dots with Platelets.

InP/ZnS quantum dots (QDs) have received a large focus in recent years as a safer alternative to heavy metal-based QDs. Given their intrinsic fluorescent imaging capabilities, these QDs can be potentially relevant for in vivo platelet imaging. The InP/ZnS QDs are synthesized and their biocompatibility investigated through the use of different phase transfer agents. Analysis of platelet function indicates that platelet-QD interaction can occur at all concentrations and for all QD permutations tested. However, as the QD concentration increases, platelet aggregation is induced by QDs alone independent of natural platelet agonists. This study helps to define a range of concentrations and coatings (thioglycolic acid and penicillamine) that are biocompatible with platelet function. With this information, the platelet-QD interaction can be identified using multiple methods. Fluorescent lifetime imaging microscopy (FLIM) and confocal studies have shown QDs localize on the surface of the platelet toward the center while showing evidence of energy transfer within the QD population. It is believed that these findings are an important stepping point for the development of fluorescent probes for platelet imaging.

Platelet zinc status regulates prostaglandin-induced signaling, altering thrombus formation.

BACKGROUND: Approximately 17.3% of the global population exhibits an element of zinc (Zn2+) deficiency. One symptom of Zn2+ deficiency is increased bleeding through impaired hemostasis. Platelets are crucial to hemostasis and are inhibited by endothelial-derived prostacyclin (prostaglandin I2 [PGI2]), which signals via adenylyl cyclase (AC) and cyclic adenosine monophosphate signaling. In other cell types, Zn2+ modulates cyclic adenosine monophosphate concentrations by changing AC and/or phosphodiesterase activity. OBJECTIVES: To investigate if Zn2+ can modulate platelet PGI2 signaling. METHODS: Platelet aggregation, spreading, and western blotting assays with Zn2+ chelators and cyclic nucleotide elevating agents were performed in washed platelets and platelet-rich plasma conditions. In vitro thrombus formation with various Zn2+ chelators and PGI2 was assessed in whole blood. RESULTS: Incubation of whole blood or washed platelets with Zn2+ chelators caused either embolization of preformed thrombi or reversal of platelet spreading, respectively. To understand this effect, we analyzed resting platelets and identified that incubation with Zn2+ chelators elevated pVASPser157, a marker of PGI2 signaling. In agreement that Zn2+ affects PGI2 signaling, addition of the AC inhibitor SQ22536 blocked Zn2+ chelation-induced platelet spreading reversal, while addition of Zn2+ blocked PGI2-mediated platelet reversal. Moreover, Zn2+ specifically blocked forskolin-mediated AC reversal of platelet spreading. Finally, PGI2 inhibition of platelet aggregation and in vitro thrombus formation was potentiated in the presence of low doses of Zn2+ chelators, increasing its effectiveness in inducing platelet inhibition. CONCLUSION: Zn2+ chelation potentiates platelet PGI2 signaling, elevating PGI2's ability to prevent effective platelet activation, aggregation, and thrombus formation.

Australian lobbyist registers are not serving the purposes they were designed for.

INTRODUCTION AND AIMS: There is widespread concern about the nature, extent and impacts of lobbying by industries selling unhealthy commodities, which threatens public health and undermines important democratic processes. In the last decade, all Australian jurisdictions (except the Northern Territory) have established lobbyist registers with the stated objective of increasing the capacity of government and the public to scrutinise lobbying. Our aim was to assess whether the registers are fulfilling this objective. DESIGN AND METHODS: We conducted web searches of registers in Australian jurisdictions in 2014 and 2015 to determine what type of information they collected and whether data were accessible. We supplemented searches with e-mails and phone calls to registrars to clarify policies and seek additional information. RESULTS: We found that the data were lacking in critical details and historical information was difficult or impossible to obtain. None of the registers required in-house lobbyists to register or to be bound by the Lobbying Codes of Conduct. None required that informal lobbying (e.g. by government relations staff within a company) be recorded, and none provided detailed information about the nature and extent of lobbying activities. DISCUSSION AND CONCLUSIONS: The registers do not meet the stated objective of making lobbying activity transparent to the Australian public. Timely access to comprehensive information is essential to help promote the rational development of policy concerning tobacco, alcohol and gambling problems. There is an urgent need to reform lobbyist registers to ensure that they are comprehensive and transparent.

Seasonal Changes in Functional Fitness and Neurocognitive Assessments in Youth Ice-Hockey Players.

Avery, M, Wattie, N, Holmes, M, and Dogra, S. Seasonal changes in functional fitness and neurocognitive assessments in youth ice-hockey players. J Strength Cond Res 32(11): 3143-3152, 2018-Deficits in balance and strength combined with differing rates of sensory and motor neural development may increase risk of sports-related injury in youth. This study evaluated changes in functional fitness and concussion status over the course of a competitive season in youth ice-hockey players, and examined the relationship between these variables and injury occurrence. Thirty-six participants (8.9 ± 1.1 years) completed preseason and postseason assessments including anthropometric measurements, the functional movement screen (FMS), Lower Quarter Y-Balance Test (YBT-LQ), and a computerized neurocognitive assessment (ImPACT). Paired-samples t-tests were used to compare preseason and postseason data. Independent samples t-tests were used to compare FMS, YBT-LQ, and ImPACT scores between injured and uninjured participants at baseline. The mean composite score of the FMS was not statistically different between preseason (15.1 ± 1.8) and postseason (15.6 ± 2.3, p < 0.16). The YBT-LQ composite score showed a decrease in reach distance scores between preseason (86.10 ± 6.00) and postseason (83.20 ± 5.40, p < 0.001). Neurocognitive assessment scores improved in both the injured and uninjured participants. There were no significant relationships between FMS scores, YBT-LQ, and injury incidence. Results from our study provide insight into changes in functional fitness levels and neurocognitive scores over the course of a season in youth ice-hockey players. These findings provide insight into expected changes over the course of a season and provide context for injury risk monitoring by coaches.

Mechanisms of influence: Alcohol industry submissions to the inquiry into fetal alcohol spectrum disorders.

INTRODUCTION AND AIMS: Industry groups with vested interests in policy regularly work to protect their profits via the endorsement of ineffective voluntary regulation and interventions, extensive lobbying activity and minimising the health impact of consumption behaviours. This study aims to examine all alcohol industry submissions to the Australian House of Representatives Standing Committee on Social Policy and Legal Affairs into Fetal Alcohol Spectrum Disorders (FASD), to assist in understanding how those with vested interests contribute to policy development. The analysis aims to document the strategies and arguments used by alcohol industry bodies in their submissions and to compare these with known strategies of vested-interest groups. DESIGN AND METHODS: All 92 submissions to the Inquiry were screened to include only those submitted by alcohol industry bodies (five submissions). Content domains were derived based on the major themes emerging from the industry submissions and on common vested-interest behaviours identified in previous literature. RESULTS: The following content categories were identified: Concerns about FASD; Current industry activities and FASD prevention; Value of mandatory warning labels; and Credibility of independent public health researchers and organisations. DISCUSSION AND CONCLUSIONS: Alcohol industry submissions sought to undermine community concern, debate the evidence, promote ineffective measure which are no threat to the profit margins and attack independent health professionals and researchers. In doing so, their behaviour is entirely consistent with their responses to other issues, such as violence and chronic health, and copies the tactics employed by the tobacco industry. [Avery MR, Droste N, Giorgi C, Ferguson A, Martino F, Coomber K, Miller P. Mechanisms of influence: Alcohol industry submissions to the inquiry into fetal alcohol spectrum disorders. Drug Alcohol Rev 2016;35:665-672].

dSarm/Sarm1 is required for activation of an injury-induced axon death pathway.

Axonal and synaptic degeneration is a hallmark of peripheral neuropathy, brain injury, and neurodegenerative disease. Axonal degeneration has been proposed to be mediated by an active autodestruction program, akin to apoptotic cell death; however, loss-of-function mutations capable of potently blocking axon self-destruction have not been described. Here, we show that loss of the Drosophila Toll receptor adaptor dSarm (sterile α/Armadillo/Toll-Interleukin receptor homology domain protein) cell-autonomously suppresses Wallerian degeneration for weeks after axotomy. Severed mouse Sarm1 null axons exhibit remarkable long-term survival both in vivo and in vitro, indicating that Sarm1 prodegenerative signaling is conserved in mammals. Our results provide direct evidence that axons actively promote their own destruction after injury and identify dSarm/Sarm1 as a member of an ancient axon death signaling pathway.

WldS prevents axon degeneration through increased mitochondrial flux and enhanced mitochondrial Ca2+ buffering.

Wld(S) (slow Wallerian degeneration) is a remarkable protein that can suppress Wallerian degeneration of axons and synapses, but how it exerts this effect remains unclear. Here, using Drosophila and mouse models, we identify mitochondria as a key site of action for Wld(S) neuroprotective function. Targeting the NAD(+) biosynthetic enzyme Nmnat to mitochondria was sufficient to fully phenocopy Wld(S), and Wld(S) was specifically localized to mitochondria in synaptic preparations from mouse brain. Axotomy of live wild-type axons induced a dramatic spike in axoplasmic Ca(2+) and termination of mitochondrial movement-Wld(S) potently suppressed both of these events. Surprisingly, Wld(S) also promoted increased basal mitochondrial motility in axons before injury, and genetically suppressing mitochondrial motility in vivo dramatically reduced the protective effect of Wld(S). Intriguingly, purified mitochondria from Wld(S) mice exhibited enhanced Ca(2+) buffering capacity. We propose that the enhanced Ca(2+) buffering capacity of Wld(S+) mitochondria leads to increased mitochondrial motility, suppression of axotomy-induced Ca(2+) elevation in axons, and thereby suppression of Wallerian degeneration.

Wld S requires Nmnat1 enzymatic activity and N16-VCP interactions to suppress Wallerian degeneration.

Slow Wallerian degeneration (Wld(S)) encodes a chimeric Ube4b/nicotinamide mononucleotide adenylyl transferase 1 (Nmnat1) fusion protein that potently suppresses Wallerian degeneration, but the mechanistic action of Wld(S) remains controversial. In this study, we characterize Wld(S)-mediated axon protection in vivo using Drosophila melanogaster. We show that Nmnat1 can protect severed axons from autodestruction but at levels significantly lower than Wld(S), and enzyme-dead versions of Nmnat1 and Wld(S) exhibit severely reduced axon-protective function. Interestingly, a 16-amino acid N-terminal domain of Wld(S) (termed N16) accounts for the differences in axon-sparing activity between Wld(S) and Nmnat1, and N16-dependent enhancement of Nmnat1-protective activity in Wld(S) requires the N16-binding protein valosin-containing protein (VCP)/TER94. Thus, Wld(S)-mediated suppression of Wallerian degeneration results from VCP-N16 interactions and Nmnat1 activity converging in vivo. Surprisingly, mouse Nmnat3, a mitochondrial Nmnat enzyme that localizes to the cytoplasm in Drosophila cells, protects severed axons at levels indistinguishable from Wld(S). Thus, nuclear Nmnat activity does not appear to be essential for Wld(S)-like axon protection.

Draper-dependent glial phagocytic activity is mediated by Src and Syk family kinase signalling.

The cellular machinery promoting phagocytosis of corpses of apoptotic cells is well conserved from worms to mammals. An important component is the Caenorhabditis elegans engulfment receptor CED-1 (ref. 1) and its Drosophila orthologue, Draper. The CED-1/Draper signalling pathway is also essential for the phagocytosis of other types of 'modified self' including necrotic cells, developmentally pruned axons and dendrites, and axons undergoing Wallerian degeneration. Here we show that Drosophila Shark, a non-receptor tyrosine kinase similar to mammalian Syk and Zap-70, binds Draper through an immunoreceptor tyrosine-based activation motif (ITAM) in the Draper intracellular domain. We show that Shark activity is essential for Draper-mediated signalling events in vivo, including the recruitment of glial membranes to severed axons and the phagocytosis of axonal debris and neuronal cell corpses by glia. We also show that the Src family kinase (SFK) Src42A can markedly increase Draper phosphorylation and is essential for glial phagocytic activity. We propose that ligand-dependent Draper receptor activation initiates the Src42A-dependent tyrosine phosphorylation of Draper, the association of Shark and the activation of the Draper pathway. These Draper-Src42A-Shark interactions are strikingly similar to mammalian immunoreceptor-SFK-Syk signalling events in mammalian myeloid and lymphoid cells. Thus, Draper seems to be an ancient immunoreceptor with an extracellular domain tuned to modified self, and an intracellular domain promoting phagocytosis through an ITAM-domain-SFK-Syk-mediated signalling cascade.