The recent implementation of genomic and lipidomic approaches has produced a large body of evidence implicating the sphingolipid ceramide in a diverse range of physiological processes and as a ...critical modulator of cellular stress. In this review, we discuss from a historical perspective the most important discoveries produced over the last decade supporting a role for ceramide and its metabolites in the pathogenesis of insulin resistance and other obesity-associated metabolic diseases. Moreover, we describe how a ceramide-centric view of insulin resistance might be reconciled in the context of other prominent models of nutrient-induced insulin resistance.
It has been proposed that guanine-rich DNA forms four-stranded structures in vivo called G-quadruplexes or G4 DNA. G4 DNA has been implicated in several biological processes, but tools to study G4 ...DNA structures in cells are limited. Here we report the development of novel murine monoclonal antibodies specific for different G4 DNA structures. We show that one of these antibodies designated 1H6 exhibits strong nuclear staining in most human and murine cells. Staining intensity increased on treatment of cells with agents that stabilize G4 DNA and, strikingly, cells deficient in FANCJ, a G4 DNA-specific helicase, showed stronger nuclear staining than controls. Our data strongly support the existence of G4 DNA structures in mammalian cells and indicate that the abundance of such structures is increased in the absence of FANCJ. We conclude that monoclonal antibody 1H6 is a valuable tool for further studies on the role of G4 DNA in cell and molecular biology.
Stalled replication forks are a critical problem for the cell because they can lead to complex genome rearrangements that underlie cell death and disease. Processes such as DNA damage tolerance and ...replication fork reversal protect stalled forks from these events. A central mediator of these DNA damage responses in humans is the Rad5-related DNA translocase, HLTF. Here, we present biochemical and structural evidence that the HIRAN domain, an ancient and conserved domain found in HLTF and other DNA processing proteins, is a modified oligonucleotide/oligosaccharide (OB) fold that binds to 3′ ssDNA ends. We demonstrate that the HIRAN domain promotes HLTF-dependent fork reversal in vitro through its interaction with 3′ ssDNA ends found at forks. Finally, we show that HLTF restrains replication fork progression in cells in a HIRAN-dependent manner. These findings establish a mechanism of HLTF-mediated fork reversal and provide insight into the requirement for distinct fork remodeling activities in the cell.
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•The ancient, conserved HIRAN domain is an ssDNA 3′ end recognition module•X-ray and NMR analysis of HIRAN-ssDNA reveal the structural basis for 3′ binding•Fork reversal by HLTF requires HIRAN and the 3′ end of the nascent leading strand•HLTF restrains fork progression under conditions of nucleotide depletion
Kile et al. reveal the function and structure of the ancient and evolutionarily conserved HIRAN domain of HLTF, a dsDNA translocase involved in replication fork reversal. They show it to be a recognition module for 3′ DNA ends necessary for fork reversal in vitro and also for fork progression in vivo.
Depleted oil reservoirs are considered a viable solution to the global challenge of CO2 storage. A key concern is whether the wells can be suitably sealed with cement to hinder the escape of CO2. ...Under reservoir conditions, CO2 is in its supercritical state, and the high pressures and temperatures involved make real-time microscopic observations of cement degradation experimentally challenging. Here, we present an in situ 3D dynamic X-ray micro computed tomography (μ-CT) study of well cement carbonation at realistic reservoir stress, pore-pressure, and temperature conditions. The high-resolution time-lapse 3D images allow monitoring the progress of reaction fronts in Portland cement, including density changes, sample deformation, and mineral precipitation and dissolution. By switching between flow and nonflow conditions of CO2-saturated water through cement, we were able to delineate regimes dominated by calcium carbonate precipitation and dissolution. For the first time, we demonstrate experimentally the impact of the flow history on CO2 leakage risk for cement plugging. In-situ μ-CT experiments combined with geochemical modeling provide unique insight into the interactions between CO2 and cement, potentially helping in assessing the risks of CO2 storage in geological reservoirs.
Growth differentiation factor 15 (GDF15), a distant member of the transforming growth factor (TGF)-β family, is a secreted protein that circulates as a 25-kDa dimer. In humans, elevated GDF15 ...correlates with weight loss, and the administration of GDF15 to mice with obesity reduces body weight, at least in part, by decreasing food intake. The mechanisms through which GDF15 reduces body weight remain poorly understood, because the cognate receptor for GDF15 is unknown. Here we show that recombinant GDF15 induces weight loss in mice fed a high-fat diet and in nonhuman primates with spontaneous obesity. Furthermore, we find that GDF15 binds with high affinity to GDNF family receptor α-like (GFRAL), a distant relative of receptors for a distinct class of the TGF-β superfamily ligands. Gfral is expressed in neurons of the area postrema and nucleus of the solitary tract in mice and humans, and genetic deletion of the receptor abrogates the ability of GDF15 to decrease food intake and body weight in mice. In addition, diet-induced obesity and insulin resistance are exacerbated in GFRAL-deficient mice, suggesting a homeostatic role for this receptor in metabolism. Finally, we demonstrate that GDF15-induced cell signaling requires the interaction of GFRAL with the coreceptor RET. Our data identify GFRAL as a new regulator of body weight and as the bona fide receptor mediating the metabolic effects of GDF15, enabling a more comprehensive assessment of GDF15 as a potential pharmacotherapy for the treatment of obesity.
In a randomized trial, the addition of atezolizumab to carboplatin and etoposide resulted in significantly longer overall survival than carboplatin and etoposide alone (12.3 months vs. 10.3 months).
Pneumonia is the leading cause of death of children. Diagnostic tools include chest radiography, but guidelines do not currently recommend the use of lung ultrasound (LUS) as a diagnostic method. We ...conducted a meta-analysis to summarize evidence on the diagnostic accuracy of LUS for childhood pneumonia.
We performed a systematic search in PubMed, Embase, the Cochrane Library, Scopus, Global Health, World Health Organization-Libraries, and Latin American and Caribbean Health Sciences Literature of studies comparing LUS diagnostic accuracy against a reference standard. We used a combination of controlled key words for age <18 years, pneumonia, and ultrasound. We identified 1475 studies and selected 15 (1%) for further review. Eight studies (765 children) were retrieved for analysis, of which 6 (75%) were conducted in the general pediatric population and 2 (25%) in neonates. Eligible studies provided information to calculate sensitivity, specificity, and positive and negative likelihood ratios. Heterogeneity was assessed by using Q and I(2) statistics.
Five studies (63%) reported using highly skilled sonographers. Overall methodologic quality was high, but heterogeneity was observed across studies. LUS had a sensitivity of 96% (95% confidence interval CI: 94%-97%) and specificity of 93% (95% CI: 90%-96%), and positive and negative likelihood ratios were 15.3 (95% CI: 6.6-35.3) and 0.06 (95% CI: 0.03-0.11), respectively. The area under the receiver operating characteristic curve was 0.98. Limitations included the following: most studies included in our analysis had a low number of patients, and the number of eligible studies was also small.
Current evidence supports LUS as an imaging alternative for the diagnosis of childhood pneumonia. Recommendations to train pediatricians on LUS for diagnosis of pneumonia may have important implications in different clinical settings.
Previous studies have shown that chorus wave intensity can be modulated by Pc4‐Pc5 compressional ULF waves. In this study, we present Van Allen Probes observation of ULF wave modulating chorus wave ...intensity, which occurred deep in the magnetosphere. The ULF wave shows fundamental poloidal mode signature and mirror mode compressional nature. The observed ULF wave can modulate not only the chorus wave intensity but also the distribution of both protons and electrons. Linear growth rate analysis shows consistence with observed chorus intensity variation at low frequency (f <∼ 0.3fce), but cannot account for the observed higher‐frequency chorus waves, including the upper band chorus waves. This suggests the chorus waves at higher‐frequency ranges require nonlinear mechanisms. In addition, we use combined observations of Radiation Belt Storm Probes (RBSP) A and B to verify that the ULF wave event is spatially local and does not last long.
Key Points
ULF wave modulation of pitch angle distributions of both electrons and protons and chorus intensity occurs deep in the magnetosphere
This ULF wave shows signatures of fundamental poloidal mode of field line resonance and mirror wave nature
Linear growth rate calculation supports instability below 0.3 fce, while observed chorus at higher frequency requires nonlinear mechanisms
Single-cell RNA sequencing has enabled the decomposition of complex tissues into functionally distinct cell types. Often, investigators wish to assign cells to cell types through unsupervised ...clustering followed by manual annotation or via 'mapping' to existing data. However, manual interpretation scales poorly to large datasets, mapping approaches require purified or pre-annotated data and both are prone to batch effects. To overcome these issues, we present CellAssign, a probabilistic model that leverages prior knowledge of cell-type marker genes to annotate single-cell RNA sequencing data into predefined or de novo cell types. CellAssign automates the process of assigning cells in a highly scalable manner across large datasets while controlling for batch and sample effects. We demonstrate the advantages of CellAssign through extensive simulations and analysis of tumor microenvironment composition in high-grade serous ovarian cancer and follicular lymphoma.
Guidelines do not currently recommend the use of lung ultrasound (LUS) as an alternative to chest X-ray (CXR) or chest computerized tomography (CT) scan for the diagnosis of pneumonia. We conducted a ...meta-analysis to summarize existing evidence of the diagnostic accuracy of LUS for pneumonia in adults.
We conducted a systematic search of published studies comparing the diagnostic accuracy of LUS against a referent CXR or chest CT scan and/or clinical criteria for pneumonia in adults aged ≥18 years. Eligible studies were required to have a CXR and/or chest CT scan at the time of evaluation. We manually extracted descriptive and quantitative information from eligible studies, and calculated pooled sensitivity and specificity using the Mantel-Haenszel method and pooled positive and negative likelihood ratios (LR) using the DerSimonian-Laird method. We assessed for heterogeneity using the Q and I2 statistics.
Our initial search strategy yielded 2726 articles, of which 45 (1.7%) were manually selected for review and 10 (0.4%) were eligible for analyses. These 10 studies provided a combined sample size of 1172 participants. Six studies enrolled adult patients who were either hospitalized or admitted to Emergency Departments with suspicion of pneumonia and 4 studies enrolled critically-ill adult patients. LUS was performed by highly-skilled sonographers in seven studies, by trained physicians in two, and one did not mention level of training. All studies were conducted in high-income settings. LUS took a maximum of 13 minutes to conduct. Nine studies used a 3.5-5 MHz micro-convex transducer and one used a 5-9 MHz convex probe. Pooled sensitivity and specificity for the diagnosis of pneumonia using LUS were 94% (95% CI, 92%-96%) and 96% (94%-97%), respectively; pooled positive and negative LRs were 16.8 (7.7-37.0) and 0.07 (0.05-0.10), respectively; and, the area-under-the-ROC curve was 0.99 (0.98-0.99).
Our meta-analysis supports that LUS, when conducted by highly-skilled sonographers, performs well for the diagnosis of pneumonia. General practitioners and Emergency Medicine physicians should be encouraged to learn LUS since it appears to be an established diagnostic tool in the hands of experienced physicians.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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