EFA6 regulates selective polarised transport and axon regeneration from the axon initial segment

Central nervous system (CNS) axons lose their intrinsic ability to regenerate with maturity, whilst peripheral (PNS) axons do not. A key difference between these neuronal types is their ability to transport integrins into axons. Integrins can mediate PNS regeneration, but are excluded from adult CNS axons along with their rab11 carriers. We reasoned that exclusion of the contents of rab11 vesicles including integrins might contribute to the intrinsic inability of CNS neurons to regenerate, and investigated this using laser axotomy. We identify a novel regulator of selective axon transport and regeneration, the ARF6 GEF EFA6. EFA6 exerts its effects from a location within the axon initial segment (AIS). EFA6 does not localise here in DRG axons, and in these neurons, ARF activation is counteracted by an ARF-GAP which is absent from the CNS, ACAP1. Depleting EFA6 from cortical neurons permits endosomal integrin transport and enhances regeneration, whilst overexpressing EFA6 prevents DRG regeneration. Our results demonstrate that ARF6 is an intrinsic regulator of regenerative capacity, implicating EFA6 as a focal molecule linking the axon initial segment, signalling and transport

Public Trust in Information Media of the Spread of Covid-19

This article discusses Public Trust in the Information Media for the Spread of Covid-19. Framing the news is necessary to maintain a positive perspective from the public towards the government. This will be an important action for the government to solve the pandemic because collaboration between the community and the government is needed. There have been efforts made by the government in fighting COVID-19 until finally guaranteed public trust should be the main goal of online news framing in the current pandemic situation. The general public should be able to sort out which news is right and which is wrong so that we do not have bad speculations about the people who are victims of this Covid-19. Framing the news is necessary to maintain a positive perspective from the public towards the government. This will be an important action for the government to solve the pandemic because collaboration between the community and the government is needed. There have been efforts made by the government in fighting COVID-19 until finally guaranteed public trust should be the main goal of online news framing in a pandemic situation

Acute Tentorial Subdural Hematoma Caused by Rupture of the Posterior Cerebral Artery after Minor Trauma—A Case Report

Acute subdural hematoma (aSDH) is a common pathology encountered after head trauma. Only a minority of aSDHs have an arterial source. In this article, we report a case of aSDH originating from a traumatic pseudoaneurysm of the distal segment of posterior cerebral artery (PCA), diagnosed several days after the initial minor trauma and successfully treated with endovascular coiling. This case emphasizes the importance of searching for vascular pathology when the localization, severity or relapsing course of the intracranial hemorrhage does not fully correspond to the severity of initial trauma and when the bleeding has a delayed onset. Characteristics, diagnostics and treatment possibilities of traumatic cerebral aneurysms, an important cause of arterial aSDH, are described in the article

The calsyntenins--a family of postsynaptic membrane proteins with distinct neuronal expression patterns.

We have identified two novel postsynaptic membrane proteins that are highly similar to calsyntenin-1 in their extracellular parts but vary considerably in their cytoplasmic segment. Calsyntenin-1 has recently been identified in our lab as a postsynaptic membrane protein with a highly acidic cytoplasmic segment with putative Ca(2+)-binding capacity (Vogt et al., 2001, Mol. Cell. Neurosci. 17: 151-166). Based on their structural similarity to calsyntenin-1, we have called the novel proteins calsyntenin-2 and -3, respectively. By immunoelectron microscopy, the calsyntenin protein family was localized in the postsynaptic membrane of excitatory central nervous system (CNS) synapses. In situ hybridization analysis revealed that calsyntenin-1 was abundant in most neurons of the CNS with relatively little variation in its expression level. Calsyntenin-2 and -3 expressions varied much more with highest levels in GABAergic neurons. Based on their distinct expression patterns and the differences in their cytoplasmic segments, we suggest a cell-type-specific functional role for the three calsyntenins in excitatory synaptic transmission

Calsyntenin-1 shelters APP from proteolytic processing during anterograde axonal transport

Endocytosis of amyloid-β precursor protein (APP) is thought to represent the major source of substrate for the production of the amyloidogenic Aβ peptide by the β-secretase BACE1. The irreversible nature of proteolytic cleavage implies the existence of an efficient replenishment route for APP from its sites of synthesis to the cell surface. We recently found that APP exits the trans-Golgi network in intimate association with calsyntenin-1, a transmembrane cargo-docking protein for Kinesin-1-mediated vesicular transport. Here we characterized the function of calsyntenin-1 in neuronal APP transport using selective immunoisolation of intracellular trafficking organelles, immunocytochemistry, live-imaging, and RNAi. We found that APP is co-transported with calsyntenin-1 along axons to early endosomes in the central region of growth cones in carriers that exclude the α-secretase ADAM10. Intriguingly, calsyntenin-1/APP organelles contained BACE1, suggesting premature cleavage of APP along its anterograde path. However, we found that APP contained in calsyntenin-1/APP organelles was stable. We further analyzed vesicular trafficking of APP in cultured hippocampal neurons, in which calsyntenin-1 was reduced by RNAi. We found a markedly increased co-localization of APP and ADAM10 in axons and growth cones, along with increased proteolytic processing of APP and Aβ secretion in these neurons. This suggested that the reduced capacity for calsyntenin-1-dependent APP transport resulted in mis-sorting of APP into additional axonal carriers and, therefore, the premature encounter of unprotected APP with its ectodomain proteases. In combination, our results characterize calsyntenin-1/APP organelles as carriers for sheltered anterograde axonal transport of APP

Risk factors for hepatitis C virus infection at a large urban emergency department

In 2020, Centers for Disease Control and Prevention (CDC) released guidelines recommending HCV screening in all adults 18 years and older. In the current study, we aimed to identify risk factors for HCV infection in an ED population. We performed a retrospective analysis of ED patients ≥ 18 years who were screened for HCV between 28 November 2018, and 27 November 2019, at a single urban, quaternary referral academic hospital. An HCV-antibody immunoassay (HCV-Ab) was used for screening; positive results were confirmed by measuring HCV ribonucleic acid (RNA). The outcome of interest was the number of new HCV diagnoses (presence of viremia by HCV RNA testing). Multiple logistic regression models were used to identify risk factors associated with a new HCV diagnosis. 16,722 adult patients were screened for HCV (mean age: 46 ± 15 years; 51% female). HCV seroprevalence was 5%. Independent risk factors for HCV included increasing age [10-year aOR 1.26 (95% CI 1.23, 1.30)], male sex [aOR 1.25 (95% CI 1.03, 1.51)], undomiciled housing status [aOR 2.8 (95% CI 2.3, 3.5)], history of tobacco use [aOR 3.0 (95% CI 2.3, 3.9)], history of illicit drug use [aOR 3.6 (95% CI 2.9, 4.5)], Medicaid insurance status [aOR 4.0 (95% CI 2.9, 5.5)] and Medicare insurance status [aOR 1.6 (95% CI 1.1, 2.2)].The ED services a high-risk population with regards to HCV infection. These data support universal screening of ED patients for HCV. Risk factor profiles could improve targeted screening at institutions without universal testing protocols

Calsyntenin-1 regulates targeting of dendritic NMDA receptors and dendritic spine maturation in CA1 hippocampal pyramidal cells during postnatal development

Calsyntenin-1 is a transmembrane cargo-docking protein important for kinesin-1-mediated fast transport of membrane-bound organelles that exhibits peak expression levels at postnatal day 7. However, its neuronal function during postnatal development remains unknown. We generated a knock-out mouse to characterize calsyntenin-1 function in juvenile mice. In the absence of calsyntenin-1, synaptic transmission was depressed. To address the mechanism, evoked EPSPs were analyzed revealing a greater proportion of synaptic GluN2B subunit-containing receptors typical for less mature synapses. This imbalance was due to a disruption in calsyntenin-1-mediated dendritic transport of NMDA receptor subunits. As a consequence of increased expression of GluN2B subunits, NMDA receptor-dependent LTP was enhanced at Schaffer collateral-CA1 pyramidal cell synapses. Interestingly, these defects were accompanied by a decrease in dendritic arborization and increased proportions of immature filopodia-like dendritic protrusions at the expense of thin-type dendritic spines in CA1 pyramidal cells. Thus, these results highlight a key role for calsyntenin-1 in the transport of NMDA receptors to synaptic targets, which is necessary for the maturation of neuronal circuits during early development