Ebola virus (EBOV) is an enveloped RNA virus that causes hemorrhagic fever in humans and non-human primates. Infection requires internalization from the cell surface and trafficking to a late ...endocytic compartment, where viral fusion occurs, providing a conduit for the viral genome to enter the cytoplasm and initiate replication. In a concurrent study, we identified clomiphene as a potent inhibitor of EBOV entry. Here, we screened eleven inhibitors that target the same biosynthetic pathway as clomiphene. From this screen we identified six compounds, including U18666A, that block EBOV infection (IC(50) 1.6 to 8.0 µM) at a late stage of entry. Intriguingly, all six are cationic amphiphiles that share additional chemical features. U18666A induces phenotypes, including cholesterol accumulation in endosomes, associated with defects in Niemann-Pick C1 protein (NPC1), a late endosomal and lysosomal protein required for EBOV entry. We tested and found that all six EBOV entry inhibitors from our screen induced cholesterol accumulation. We further showed that higher concentrations of cationic amphiphiles are required to inhibit EBOV entry into cells that overexpress NPC1 than parental cells, supporting the contention that they inhibit EBOV entry in an NPC1-dependent manner. A previously reported inhibitor, compound 3.47, inhibits EBOV entry by blocking binding of the EBOV glycoprotein to NPC1. None of the cationic amphiphiles tested had this effect. Hence, multiple cationic amphiphiles (including several FDA approved agents) inhibit EBOV entry in an NPC1-dependent fashion, but by a mechanism distinct from that of compound 3.47. Our findings suggest that there are minimally two ways of perturbing NPC1-dependent pathways that can block EBOV entry, increasing the attractiveness of NPC1 as an anti-filoviral therapeutic target.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Characterization of how the microenvironment, or niche, regulates stem cell activity is central to understanding stem cell biology and to developing strategies for the therapeutic manipulation of ...stem cells. Low oxygen tension (hypoxia) is commonly thought to be a shared niche characteristic in maintaining quiescence in multiple stem cell types. However, support for the existence of a hypoxic niche has largely come from indirect evidence such as proteomic analysis, expression of hypoxia inducible factor-1α (Hif-1α) and related genes, and staining with surrogate hypoxic markers (for example, pimonidazole). Here we perform direct in vivo measurements of local oxygen tension (pO2) in the bone marrow of live mice. Using two-photon phosphorescence lifetime microscopy, we determined the absolute pO2 of the bone marrow to be quite low (<32 mm Hg) despite very high vascular density. We further uncovered heterogeneities in local pO2, with the lowest pO2 (∼9.9 mm Hg, or 1.3%) found in deeper peri-sinusoidal regions. The endosteal region, by contrast, is less hypoxic as it is perfused with small arteries that are often positive for the marker nestin. These pO2 values change markedly after radiation and chemotherapy, pointing to the role of stress in altering the stem cell metabolic microenvironment.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The swine-origin A(H1N1) influenza virus that has emerged in humans in early 2009 has raised concerns about pandemic developments. In a ferret pathogenesis and transmission model, the 2009 A(H1N1) ...influenza virus was found to be more pathogenic than a seasonal A(H1N1) virus, with more extensive virus replication occurring in the respiratory tract. Replication of seasonal A(H1N1) virus was confined to the nasal cavity of ferrets, but the 2009 A(H1N1) influenza virus also replicated in the trachea, bronchi, and bronchioles. Virus shedding was more abundant from the upper respiratory tract for 2009 A(H1N1) influenza virus as compared with seasonal virus, and transmission via aerosol or respiratory droplets was equally efficient. These data suggest that the 2009 A(H1N1) influenza virus has the ability to persist in the human population, potentially with more severe clinical consequences.
In this study, the authors designed checklists to guide care during operating-room crises and evaluated them in a simulated operating room. The availability of checklists improved adherence to best ...practices by operating-room teams during simulations of surgical crises.
Operating-room crises (e.g., massive hemorrhage and cardiac arrest) are high-risk, stressful events that require rapid and coordinated care in a time-critical setting. The reported incidence may be rare for an individual practitioner,
1
but the aggregate incidence for a hospital with 10,000 operations a year is estimated to be approximately 145 such events annually.
2
These are situations in which the way the team cares for a patient will make the difference between life and death. Failure to effectively manage life-threatening complications in surgical patients has been recognized as the largest source of variation in surgical mortality among hospitals.
3
–
7
Small-scale studies . . .
A single hematopoietic stem cell (HSC) is capable of reconstituting hematopoiesis and maintaining homeostasis by balancing self-renewal and cell differentiation. The mechanisms of HSC division ...balance, however, are not yet defined. Here we demonstrate, by characterizing at the single-cell level a purified and minimally heterogeneous murine Tie2⁺ HSC population, that these top hierarchical HSCs preferentially undergo symmetric divisions. The induction of mitophagy, a quality control process in mitochondria, plays an essential role in self-renewing expansion of Tie2⁺ HSCs. Activation of the PPAR (peroxisome proliferator-activated receptor)-fatty acid oxidation pathway promotes expansion of Tie2⁺ HSCs through enhanced Parkin recruitment in mitochondria. These metabolic pathways are conserved in human TIE2⁺ HSCs. Our data thus identify mitophagy as a key mechanism of HSC expansion and suggest potential methods of cell-fate manipulation through metabolic pathways.
Neuroplasticity can be defined as the ability of the nervous system to respond to intrinsic or extrinsic stimuli by reorganizing its structure, function and connections. Major advances in the ...understanding of neuroplasticity have to date yielded few established interventions. To advance the translation of neuroplasticity research towards clinical applications, the National Institutes of Health Blueprint for Neuroscience Research sponsored a workshop in 2009. Basic and clinical researchers in disciplines from central nervous system injury/stroke, mental/addictive disorders, paediatric/developmental disorders and neurodegeneration/ageing identified cardinal examples of neuroplasticity, underlying mechanisms, therapeutic implications and common denominators. Promising therapies that may enhance training-induced cognitive and motor learning, such as brain stimulation and neuropharmacological interventions, were identified, along with questions of how best to use this body of information to reduce human disability. Improved understanding of adaptive mechanisms at every level, from molecules to synapses, to networks, to behaviour, can be gained from iterative collaborations between basic and clinical researchers. Lessons can be gleaned from studying fields related to plasticity, such as development, critical periods, learning and response to disease. Improved means of assessing neuroplasticity in humans, including biomarkers for predicting and monitoring treatment response, are needed. Neuroplasticity occurs with many variations, in many forms, and in many contexts. However, common themes in plasticity that emerge across diverse central nervous system conditions include experience dependence, time sensitivity and the importance of motivation and attention. Integration of information across disciplines should enhance opportunities for the translation of neuroplasticity and circuit retraining research into effective clinical therapies.
Schizophrenia affects around 1% of the global population. Functional connectivity extracted from resting-state functional magnetic resonance imaging (rs-fMRI) has previously been used to study ...schizophrenia and has great potential to provide novel insights into the disorder. Some studies have shown abnormal functional connectivity in the default mode network (DMN) of individuals with schizophrenia, and more recent studies have shown abnormal dynamic functional connectivity (dFC) in individuals with schizophrenia. However, DMN dFC and the link between abnormal DMN dFC and symptom severity have not been well-characterized.
Resting-state fMRI data from subjects with schizophrenia (SZ) and healthy controls (HC) across two datasets were analyzed independently. We captured seven maximally independent subnodes in the DMN by applying group independent component analysis and estimated dFC between subnode time courses using a sliding window approach. A clustering method separated the dFCs into five reoccurring brain states. A feature selection method modeled the difference between SZs and HCs using the state-specific FC features. Finally, we used the transition probability of a hidden Markov model to characterize the link between symptom severity and dFC in SZ subjects.
We found decreases in the connectivity of the anterior cingulate cortex (ACC) and increases in the connectivity between the precuneus (PCu) and the posterior cingulate cortex (PCC) (i.e., PCu/PCC) of SZ subjects. In SZ, the transition probability from a state with weaker PCu/PCC and stronger ACC connectivity to a state with stronger PCu/PCC and weaker ACC connectivity increased with symptom severity.
To our knowledge, this was the first study to investigate DMN dFC and its link to schizophrenia symptom severity. We identified reproducible neural states in a data-driven manner and demonstrated that the strength of connectivity within those states differed between SZs and HCs. Additionally, we identified a relationship between SZ symptom severity and the dynamics of DMN functional connectivity. We validated our results across two datasets. These results support the potential of dFC for use as a biomarker of schizophrenia and shed new light upon the relationship between schizophrenia and DMN dynamics.
IMPORTANCE: Childhood community-acquired pneumonia (CAP) is usually treated with 10 days of antibiotics. Shorter courses may be effective with fewer adverse effects and decreased potential for ...antibiotic resistance. OBJECTIVE: To compare a short (5-day) vs standard (10-day) antibiotic treatment strategy for CAP in young children. DESIGN, SETTING, AND PARTICIPANTS: Randomized double-blind placebo-controlled clinical trial in outpatient clinic, urgent care, or emergency settings in 8 US cities. A total of 380 healthy children aged 6 to 71 months with nonsevere CAP demonstrating early clinical improvement were enrolled from December 2, 2016, to December 16, 2019. Data were analyzed from January to September 2020. INTERVENTION: On day 6 of their originally prescribed therapy, participants were randomized 1:1 to receive 5 days of matching placebo or 5 additional days of the same antibiotic. MAIN OUTCOMES AND MEASURES: The primary end point was the end-of-treatment response adjusted for duration of antibiotic risk (RADAR), a composite end point that ranks each child’s clinical response, resolution of symptoms, and antibiotic-associated adverse effects in an ordinal desirability of outcome ranking (DOOR). Within each DOOR rank, participants were further ranked by the number of antibiotic days, assuming that shorter antibiotic durations were more desirable. Using RADAR, the probability of a more desirable outcome was estimated for the short- vs standard-course strategy. In a subset of children, throat swabs were collected between study days 19 and 25 to quantify antibiotic resistance genes in oropharyngeal flora. RESULTS: A total of 380 children (189 randomized to short course and 191 randomized to standard course) made up the study population. The mean (SD) age was 35.7 (17.2) months, and 194 participants (51%) were male. Of the included children, 8 were Asian, 99 were Black or African American, 234 were White, 32 were multiracial, and 7 were of unknown or unreported race; 33 were Hispanic or Latino, 344 were not Hispanic or Latino, and 3 were of unknown or unreported ethnicity. There were no differences between strategies in the DOOR or its individual components. Fewer than 10% of children in either strategy had an inadequate clinical response. The short-course strategy had a 69% (95% CI, 63-75) probability of a more desirable RADAR outcome compared with the standard-course strategy. A total of 171 children were included in the resistome analysis. The median (range) number of antibiotic resistance genes per prokaryotic cell (RGPC) was significantly lower in the short-course strategy compared with the standard-course strategy for total RGPC (1.17 0.35-2.43 vs 1.33 0.46-11.08; P = .01) and β-lactamase RGPC (0.55 0.18-1.24 vs 0.60 0.21-2.45; P = .03). CONCLUSIONS AND RELEVANCE: In this study, among children responding to initial treatment for outpatient CAP, a 5-day antibiotic strategy was superior to a 10-day strategy. The shortened approach resulted in similar clinical response and antibiotic-associated adverse effects, while reducing antibiotic exposure and resistance. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02891915.
Abstract
Background
Retinal degeneration is a disease affecting the eye, which is an immune-privileged site because of its anatomical and physiological properties. Alterations in retinal ...homeostasis—because of injury, disease, or aging—initiate inflammatory cascades, where peripheral leukocytes (PL) infiltrate the parenchyma, leading to retinal degeneration. So far, research on PL's role in retinal degeneration was limited to observing a few cell types at specific times or sectioning the tissue. This restricted our understanding of immune cell interactions and response duration.
Methods
In vivo microscopy in preclinical mouse models can overcome these limitations enabling the spatio-temporal characterization of PL dynamics. Through in vivo imaging, we assessed structural and fluorescence changes in response to a focal injury at a defined location over time. We also utilized minimally invasive techniques, pharmacological interventions, and knockout (KO) mice to determine the role of PL in local inflammation. Furthermore, we investigated PL abundance and localization during retinal degeneration in human eyes by histological analysis to assess to which extent our preclinical study translates to human retinal degeneration.
Results
We demonstrate that PL, especially T cells, play a detrimental role during retinal injury response. In mice, we observed the recruitment of helper and cytotoxic T cells in the parenchyma post-injury, and T cells also resided in the macula and peripheral retina in pathological conditions in humans. Additionally, we found that the pharmacological PL reduction and genetic depletion of T-cells reduced injured areas in murine retinas and rescued the blood–retina barrier (BRB) integrity. Both conditions promoted morphological changes of Cx3cr1
+
cells, including microglial cells, toward an amoeboid phenotype during injury response. Interestingly, selective depletion of CD8
+
T cells accelerated recovery of the BRB compared to broader depletions. After anti-CD8 treatment, the retinal function improved, concomitant to a beneficial immune response.
Conclusions
Our data provide novel insights into the adaptive immune response to retinal injury in mice and human retinal degeneration. Such information is fundamental to understanding retinal disorders and developing therapeutics to modulate immune responses to retinal degeneration safely.
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