Background and purpose
Previous studies suggested that the overall burden of prior infections contributes to cardiovascular diseases and stroke. In the present study, the association between ...infectious burden (IB) and Alzheimer's disease (AD) was examined.
Methods
Antibody titers to common infectious pathogens including cytomegalovirus (CMV), herpes simplex virus type 1 (HSV‐1), Borrelia burgdorferi, Chlamydophila pneumoniae and Helicobacter pylori were measured by enzyme‐linked immunosorbent assay in 128 AD patients and 135 healthy controls. IB was defined as a composite serological measure of exposure to these common pathogens.
Results
Seropositivities toward zero−two, three and four−five of these pathogens were found in 44%, 40% and 16% of healthy controls but in 20%, 44% and 36% of AD patients, respectively. IB, bacterial burden and viral burden were independently associated with AD after adjusting for age, gender, education, APOE genotype and various comorbidities. Mini‐Mental State Examination scores were negatively correlated with IB in all cases. Serum beta‐amyloid protein (Aβ) levels (i.e. Aβ40, Aβ42 and total Aβ) and inflammatory cytokines (i.e. interferon‐γ, tumor necrosis factor α, interleukin‐1β and interleukin‐6) in individuals exposed to four−five infectious pathogens were significantly higher than those exposed to zero−two or three pathogens.
Conclusions
IB consisting of CMV, HSV‐1, B. burgdorferi, C. pneumoniae and H. pylori is associated with AD. This study supports the role of infection/inflammation in the etiopathogenesis of AD.
Click here to view the accompanying paper in this issue. Videocasts of this article are available in: English: http://player.polyv.net/videos/player.swf?vid=f6ee5715d9808c7a481b7ae727da00dd_f Mandarin: http://player.polyv.net/videos/f6ee5715d98ae743a9b0509d0900c91f_f.swf
Highlights • CP−/− mice and mice that received FAC had high levels of brain iron. • Brain iron accumulation exacerbated TH-positive neurons apoptosis in MPTP-treated mice. • DFO reduced the neuronal ...damage in MPTP-treated CP−/− mice. • Increased oxidative stress was involved in cell apoptosis exacerbated by the increased brain iron.
The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10
electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV ...energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays
. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref.
). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane
, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.
High-energy photons from the Crab Nebula
The Crab Nebula contains a pulsar that excites the surrounding gas to emit high-energy radiation. The combination of the pulsar's youth and nearby location ...makes the nebula the brightest gamma-ray source in the sky. The LHAASO Collaboration report observations of this source at energies of tera– to peta–electron volts, extending the spectrum of this prototypical object. They combine these data with observations at lower energies to model the physics of the emission process. The multiwave-length data can be explained by a combination of synchrotron radiation and inverse Compton scattering.
Science
, abg5137, this issue p.
425
Detection of the Crab Nebula at peta–electron volt energies constrains the gamma-ray emission mechanism.
The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar’s rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10
−4
to 1.1 peta–electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta–electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron’s size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta–electron volt electrons, 2.5 × 10
36
ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta–electron volt protons to the production of the highest-energy gamma rays.
HUBS: Hot Universe Baryon Surveyor Cui, W.; Chen, L.-B.; Gao, B. ...
Journal of low temperature physics,
04/2020, Letnik:
199, Številka:
1-2
Journal Article
Recenzirano
Hot Universe Baryon Surveyor (HUBS) is proposed in China as a major X-ray mission for the next decade. It is designed to be highly focused scientifically, with two primary objectives: (1) detecting ...X-ray emission from hot baryons in intergalactic medium and circumgalactic medium (CGM), and characterizing their physical and chemical properties; (2) studying, based on the observations, the accretion and feedback processes that are thought to be highly relevant to the heating and chemical enrichment of the baryons in the CGM. Because of very low densities, the signal is expected to be very weak and thus technically difficult to detect. On the other hand, the spectrum of the emission is expected to be line rich, so it would be effective for detecting the hot baryons in bright emission lines. For that, an instrument with high spectral resolution, large effective area and large field of view (FoV) would be required. HUBS will couple a TES-based X-ray imaging spectrometer to a large FoV X-ray telescope to satisfy these requirements. A preliminary design of HUBS is presented.
Two-dimensional (2D) materials have been studied extensively as monolayers, vertical or lateral heterostructures. To achieve functionalization, monolayers are often patterned using soft lithography ...and selectively decorated with molecules. Here we demonstrate the growth of a family of 2D materials that are intrinsically patterned. We demonstrate that a monolayer of PtSe
can be grown on a Pt substrate in the form of a triangular pattern of alternating 1T and 1H phases. Moreover, we show that, in a monolayer of CuSe grown on a Cu substrate, strain relaxation leads to periodic patterns of triangular nanopores with uniform size. Adsorption of different species at preferred pattern sites is also achieved, demonstrating that these materials can serve as templates for selective self-assembly of molecules or nanoclusters, as well as for the functionalization of the same substrate with two different species.
Aberrant activation of c-kit proto-oncogene contributes to abnormal cell proliferation by altering the tyrosine kinase signaling and constitutes a crucial impetus for leukemogenesis. Epigenetic ...silencing of tumor-suppressive microRNAs (miRNAs) is a key oncogenic mechanism for the activation of oncogenes in tumors. In this study, several miRNAs potentially binding to the 3'-untranslated region of human c-kit mRNA were screened by luciferase reporter assays. Among these miRNAs, miR-193a was embedded in a CpG island and epigenetically repressed by promoter hypermethylation in acute myeloid leukemia (AML) cell lines and primary AML blasts, but not in normal bone marrow cells. Importantly, miR-193a levels were inversely correlated with c-kit levels measured in 9 leukemia cell lines and 27 primary AML samples. Restoring miR-193a expression in AML cells harboring c-kit mutation and/or overexpression, either by synthetic miR-193a transfection or by DNA hypomethylating agent 5-azacytidine (5-aza) treatment, resulted in a significant reduction in c-kit expression at both RNA and protein levels and inhibition of cell growth. The growth-inhibitory activity of miR-193a was associated with apoptosis and granulocytic differentiation. Moreover, 5-aza-induced c-kit reduction could be partially blocked by miR-193a inhibitor, leading to a reversal of antiproliferative and proapoptotic effects of 5-aza. These data reveal a critical role for methylation-repressed miR-193a in myeloid leukemogenesis and the therapeutic promise of upregulating miR-193a expression for c-kit-positive AML.
Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory ...(LHAASO) of the bright GRB 221009A, which serendipitously occurred within the instrument's field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger and then rose to a peak ~10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle of ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.
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