Additive manufacturing of bioactive and biodegradable porous iron-akermanite composites for bone regeneration

Advanced additive manufacturing techniques have been recently used to tackle the two fundamental challenges of biodegradable Fe-based bone-substituting materials, namely low rate of biodegradation and insufficient bioactivity. While additively manufactured porous iron has been somewhat successful in addressing the first challenge, the limited bioactivity of these biomaterials hinder their progress towards clinical application. Herein, we used extrusion-based 3D printing for additive manufacturing of iron-matrix composites containing silicate-based bioceramic particles (akermanite), thereby addressing both of the abovementioned challenges. We developed inks that carried iron and 5, 10, 15, or 20 vol% of akermanite powder mixtures for the 3D printing process and optimized the debinding and sintering steps to produce geometrically-ordered iron-akermanite composites with an open porosity of 69-71%. The composite scaffolds preserved the designed geometry and the original α-Fe and akermanite phases. The in vitro biodegradation rates of the composites were improved as much as 2.6 times the biodegradation rate of geometrically identical pure iron. The yield strengths and elastic moduli of the scaffolds remained within the range of the mechanical properties of the cancellous bone, even after 28 days of biodegradation. The composite scaffolds (10-20 vol% akermanite) demonstrated improved MC3T3-E1 cell adhesion and higher levels of cell proliferation. The cellular secretion of collagen type-1 and the alkaline phosphatase activity on the composite scaffolds (10-20 vol% akermanite) were, respectively higher than and comparable to Ti6Al4V in osteogenic medium. Taken together, these results clearly show the potential of 3D printed porous iron-akermanite composites for further development as promising bone substitutes. STATEMENT OF SIGNIFICANCE: : Porous iron matrix composites containing akermanite particles were produced by means of multi-material additive manufacturing to address the two fundamental challenges associated with biodegradable iron-based biomaterials, namely very low rate of biodegradation and insufficient bioactivity. Our porous iron-akermanite composites exhibited enhanced biodegradability and superior bioactivity compared to porous monolithic iron scaffolds. The murine bone cells proliferated on the composite scaffolds, and secreted the collagen type-1 matrix that stimulated bony-like mineralization. The results show the exceptional potential of the developed porous iron-based composite scaffolds for application as bone substitutes.

POS0774 ANTI-Sm AUTOANTIBODIES IDENTIFY A PHENOTYPE OF SEVERE SLE WITH AN ASSOCIATED SERUM BIOMARKER PROFILE

Background

Antibodies to Smith (Sm) have been described as one of the most specific autoantibodies for systemic lupus erythematosus (SLE). Other than its association with lupus nephritis, there is, however, limited understanding of its clinical significance1,2.

Objectives

To describe clinical associations and serum protein profiles of anti-Sm positivity in SLE.

Methods

Patients fulfilling SLE classification criteria who were followed longitudinally in a prospective multicentre cohort were studied according to their baseline anti-Sm antibody status. Comparison between Sm+ and Sm- patients was made using descriptive statistics. Clinical associations of Sm positivity with patient disease characteristics were studied using logistic regression. In a subset, 211 serum analytes were measured using Quantibody, Luminex and ELISA assays. Associations between serum proteins and Sm positivity were studied using Least Absolute Shrinkage and Selection Operator (LASSO) penalised regression, adjusting for demographics (age, sex, ethnicity) and medication use

Results

383 patients were studied with median (IQR) follow-up of 4.9 (2,9) years; 65 (17%) had positive anti-Sm antibodies. Sm+ patients were significantly more likely to be of non-European ancestry (OR 2.73, 95% CI 1.55-4.82, p<0.001), and to be positive for anti-dsDNA antibodies (OR 2.8, 95% CI 2.3-3.4, p<0.001), anti-RNP antibodies (OR 15.7, 95% CI 13.9-17.8, p<0.001), direct anti-globulin test (OR 2.36, 95% CI 2.07-2.7, p<0.001) and hypocomplementemia (OR 7.73, 95% CI 5.1-11.7, p<0.001). Sm+ patients were significantly more likely to have active disease during the observation period in a range of organ domains, including mucocutaneous, renal, vasculitis and fever.

More Sm+ patients had episodes of High Disease Activity Status (HDAS, SLEDAI-2K ≧10)3 (OR 3.07, 95% CI 1.70-5.54, p<0.001) and persistent active disease (time-adjusted mean SLEDAI-2K > 4) (OR 3.23. 95% CI 1.84-5.70, p<0.001). Conversely, fewer Sm+ patients attained LLDAS for ≥50% observed time (19.7% vs 41.8%, p=0.002). Sm+ patients were more likely to be treated with glucocorticoids, immunosuppressants, and rituximab. There was no significant difference in damage accrual between Sm + and Sm - patients.

In serum protein analysis (n=197, 29 Sm+), LASSO modelling retained 3 proteins associated with Sm+ status, CXCL13, IL1RL1 and FLT1, along with Asian ethnicity and age. In analysis including pairwise interaction between predictors, 28 Sm+ associated proteins were identified, including CCL4, VCAM1, IL1RL1, Fcg R IIB/C, TDGF1, CEACAM1, TIMP1, BMP5, GDF15, and TNFRSF17.

Conclusion

Anti-Sm autoantibodies, present in 17% of SLE patients, were strongly associated with classical disease manifestations, more severe disease activity, and a specific serological and proteomic profile. These findings suggest anti-Sm+ SLE as a specific disease subset.

References

[1]Barada, FA., B.S. Andrews, J.S. Davis, R.P. Taylor, Antibodies to Sm in patients with systemic lupus erythematosus. Correlation of Sm antibody titers with disease activity and other laboratory parameters. Arthritis Rheum, 1981. 24:1236-1244

[2]Arroyo-Avilla, M, Y. Santiago-Casas, G.McGwin, R.S. Cantor, M. Petri, R. Ramsey-Goldman, J.D. Reveille, R.P.Kimberly, G.S. Alarcon, L.M.Vila, E.E. Brown. Clinical Associations of anti-Smith antibodies in PROFILE: a multi-ethnic lupus cohort. 2015. 34:1217-1223

[3]Koelmeyer, R., H.T. Nim, M. Nikpour, Y.B. Sun, A. Kao, O. Guenther, E. Morand, and A. Hoi, High disease activity status suggests more severe disease and damage accrual in systemic lupus erythematosus. Lupus Sci Med, 2020. 7(1).

Acknowledgements

I would like to acknowledge participants and clinicians involved with the Australian Lupus Registry & Biobank

Disclosure of Interests

None declared

Unveiling Unequivocal Charge Stripe Order in a Prototypical Cuprate Superconductor

In the cuprates, high-temperature superconductivity, spin-density-wave order, and charge-density-wave (CDW) order are intertwined, and symmetry determination is challenging due to domain formation. We investigated the CDW in the prototypical cuprate La_{1.88}Sr_{0.12}CuO_{4} via x-ray diffraction employing uniaxial pressure as a domain-selective stimulus to establish the unidirectional nature of the CDW unambiguously. A fivefold enhancement of the CDW amplitude is found when homogeneous superconductivity is partially suppressed by magnetic field. This field-induced state provides an ideal search environment for a putative pair-density-wave state.

Premature Deaths in Africa Due To Particulate Matter Under High and Low Warming Scenarios

Sustainable development and climate change mitigation can provide enormous public health benefits via improved air quality, especially in polluted areas. We use the latest state-of-the-art composition-climate model simulations to contrast human exposure to fine particulate matter in Africa under a "baseline" scenario with high material consumption, population growth, and warming to that projected under a sustainability scenario with lower consumption, population growth, and warming. Evaluating the mortality impacts of these exposures, we find that under the low warming scenario annual premature deaths due to PM_2.5 are reduced by roughly 515,000 by 2050 relative to the high warming scenario (100,000, 175,000, 55,000, 140,000, and 45,000 in Northern, West, Central, East, and Southern Africa, respectively). This reduction rises to ∼800,000 by the 2090s, though by that time much of the difference is attributable to the projected differences in population. By contrast, during the first half of the century benefits are driven predominantly by emissions changes. Depending on the region, we find large intermodel spreads of ∼25%-50% in projected future exposures owing to different physics across the ensemble of 6 global models. The spread of projected deaths attributable to exposure to fine particulate matter, including uncertainty in the exposure-response function, are reduced in every region to ∼20%-35% by the non-linear exposure-response function. Differences between the scenarios have an even narrower spread of ∼5%-25% and are highly statistically significant in all regions for all models. These results provide valuable information for policy-makers to consider when working toward climate change mitigation and sustainable development goals.

[SARS-CoV-2 with transcription regulatory sequence motif mutation poses a greater threat]

OBJECTIVE

To analyze the mutations in transcription regulatory sequences (TRSs) of coronaviruss (CoV) to provide the basis for exploring the patterns of SARS-CoV-2 transmission and outbreak.

METHODS

A combined evolutionary and molecular functional analysis of all sets of publicly available genomic data of viruses was performed.

RESULTS

A leader transcription regulatory sequence (TRS-L) usually comprises the first 60-70 nts of the 5' UTR in a CoV genome, and the body transcription regulatory sequences (TRS-Bs) are located immediately upstream of the genes other than ORF1a and 1b. In each CoV genome, the TRS-L and TRS-Bs share a specific consensus sequence, namely the TRS motif. Any changes of nucleotide residues in the TRS motifs are defined as TRS motif mutations. Mutations in the TRS-L or multiple TRS-Bs result in superattenuated variants. The spread of super-attenuated variants may cause an increase in asymptomatic or mild infections, prolonged incubation periods and a decreased detection rate of the viruses, thus posing new challenges to SARS-CoV-2 prevention and control. The super-attenuated variants also increase their possibility of long-term coexistence with humans. The Delta variant is significantly different from all the previous variants and may lead to a large-scale transmission. The Delta variant (B.1.617.2) with TRS motif mutation has already appeared and shown signs of spreading in Singapore, which, and even the Southeast Asia, may become the new epicenter of the next wave of SARS-CoV-2 outbreak.

CONCLUSION

TRS motif mutation will occur in all variants of SARS-CoV-2 and may result in super-attenuated variants. Only super-attenuated variants with TRS motif mutations will eventually lose the abilities of cross-species transmission and causing outbreaks.

Social determinants of health influence disease activity and functional disability in Polyarticular Juvenile Idiopathic Arthritis

BACKGROUND

Social determinants of health (SDH) greatly influence outcomes during the first year of treatment in rheumatoid arthritis, a disease similar to polyarticular juvenile idiopathic arthritis (pJIA). We investigated the correlation of community poverty level and other SDH with the persistence of moderate to severe disease activity and functional disability over the first year of treatment in pJIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance Registry.

METHODS

In this cohort study, unadjusted and adjusted generalized linear mixed effects models analyzed the effect of community poverty and other SDH on disease activity, using the clinical Juvenile Arthritis Disease Activity Score-10, and disability, using the Child Health Assessment Questionnaire, measured at baseline, 6, and 12 months.

RESULTS

One thousand six hundred eighty-four patients were identified. High community poverty (≥20% living below the federal poverty level) was associated with increased odds of functional disability (OR 1.82, 95% CI 1.28-2.60) but was not statistically significant after adjustment (aOR 1.23, 95% CI 0.81-1.86) and was not associated with increased disease activity. Non-white race/ethnicity was associated with higher disease activity (aOR 2.48, 95% CI: 1.41-4.36). Lower self-reported household income was associated with higher disease activity and persistent functional disability. Public insurance (aOR 1.56, 95% CI 1.06-2.29) and low family education (aOR 1.89, 95% CI 1.14-3.12) was associated with persistent functional disability.

CONCLUSION

High community poverty level was associated with persistent functional disability in unadjusted analysis but not with persistent moderate to high disease activity. Race/ethnicity and other SDH were associated with persistent disease activity and functional disability.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Implication of microglia in ketamine-induced long-term cognitive impairment in murine pups

BACKGROUND

Ketamine, a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, is widely applicable to anesthesia, analgesia, and sedation. However, the function and mechanisms of ketamine in the long-term learning and memory function of neonatal mice are unclear.

OBJECTIVE

The present study aims to investigate whether long-term learning and memory function will be affected by multiple ketamine exposures in the early development period.

METHODS

The mRNA and protein levels were measured by RT-qPCR and western blot, respectively. The Morris Water Maze test was performed to assess spatial learning and memory.

RESULTS

We identified that neonatal exposure to ketamine downsized the positive neurons for microtubule-associated protein doublecortin (DCX) and Ki67 in hippocampal dentate gyrus at the juvenile and late adolescence stages. Double-labeling tests demonstrated that the counts of Iba1⁺ cells and Ki67⁺ cells were pronouncedly diminished with exposure to ketamine. Further, qPCR assays to screen the key factors predisposing the populations and maturation of microglia exhibited remarkable decline of CX3CR1 mRNA levels in ketamine group versus the control group. The close relation of microglia to synaptic plasticity was depicted by the significantly downregulated synaptic plasticity-related proteins NR2B and PSD-95 subsequent to multiple exposures to ketamine. Finally, we found that both the protein and mRNA levels of BDNF were markedly decreased in ketamine group versus the control group.

CONCLUSION

We found that multiple exposures to ketamine in neonatal mice lead to spatial learning and memory dysfunction. The alterations of microglial development and function are the possible mechanisms of long-term learning and memory impairment.

Effect of Deep Margin Elevation on Interfacial Gap Development of CAD/CAM Inlays after Thermomechanical Cycling

The aim of this study was to evaluate interfacial gap formation of CAD/CAM lithium disilicate inlay margins before and after thermomechanical loading.

METHODS AND MATERIALS

Mesio-occlusal-distal cavities were prepared on 12 extracted mandibular molars. The gingival margin of one proximal box was elevated with resin modified glass ionomer (RMGI) by a height of 2 mm (Group E [elevation]), and the margin of the other side served as a control (Group NE [no elevation]). Lithium disilicate computer-aided design and computer-aided manufacturing (CAD/CAM) inlays were fabricated and bonded with a self-adhesive resin cement. An aging process was simulated on the specimens under thermomechanical cycling by using a chewing simulator. Marginal integration was evaluated under scanning electron miscroscopy (SEM) using epoxy resin replicas before and after cycling. Marginal areas were stained with silver nitrate solution, and the volumetric gap was measured at the bonded interfaces using microcomputed tomography (CT) before and after cycling. Statistical analyses were performed using paired t-tests, the Wilcoxon signed rank test, and the Mann-Whitney test (a<0.05).

RESULTS

SEM showed marginal discontinuities in Group NE that increased after thermomechanical cycling. Micro-computed tomography exhibited three-dimensional dye-penetrating patterns at the interfaces before and after cycling. Interfacial disintegration was larger in Group NE before cycling (p<0.05). Thermomechanical cycling increased the gaps in both Groups NE and E (p<0.05). The gap increment from thermomechanical cycling was larger in Group NE (p<0.05).

CONCLUSIONS

Thermomechanical cycling induced interfacial disintegration at the lithium disilicate CAD/CAM inlays, with deep proximal margins. Margin elevation with RMGI placement reduced the extent of the interfacial gap formation before and after the aging simulation.

[Procyanidin B2 protects neurons from cypermethrin-induced oxidative stress through the P13K/Akt/Nrf2 signaling pathway]

OBJECTIVE

To explore whether procyanidin B2 (PCB2) regulates the P13K/Akt/Nrf2 signaling pathway to protect neurons from oxidative stress induced by cypermethrin (CYP).

METHODS

Primary cultures of cerebral cortex neurons from C57BL/6 mice were randomly divided into 5 groups: normal control group (cultured in serum-free neurobasal-B27 medium), PCB2 treatment group(treated with 5 μg/mL PCB2 for 24 h), CYP exposure group(treated with 50 μmol/L CYP for 24 h), PCB2 pretreatment group(pretreated with 5 μg/mL PCB2 for 30 min followed by exposure to 50 μmol/L CYP for 24 h), and LY294002 treatment group (pretreated with 20 μmol/L LY294002 for 30 min before treatment with PCB2 for 30 min and then CYP for 24 h).CCK-8 assay was used to analyze the neuronal viability after the treatments.Reactive oxygen species (ROS) production in the cells was detected using the fluorescent probe DCFH-DA and flow cytometry.The changes in nuclear morphology and mitochondrial membrane potential of the cells were examined with Hoechst 33342 and JC-1 staining, respectively.Western blotting was performed to detect the protein expressions of Nrf2, HO-1, p-Akt and Akt in the cells.

RESULTS

In CYP exposure group, the cells showed significantly decreased viability and mitochondrial membrane potential with obvious apoptotic morphological changes and abnormal ROS production.By comparison, the cells in PCB2 preconditioning group showed improved cell survival rate, reduced abnormalities in nuclear morphology, increased mitochondrial membrane potential, and lowered intracellular ROS production.CYP exposure caused Nrf2 nuclear translocation and up-regulated Nrf2, HO-1, p-Akt protein expressions in the cells, which were inhibited by PCB2 pretreatment.Inhibition of the P13K/Akt signaling pathway obviously neutralized the protective effect of PCB2 against CYP-induced neuronal injury.

CONCLUSIONS

PCB2 regulates the Nrf2/ARE signaling pathway by activating the P13K/Akt signaling pathway to protect mouse cerebral cortical neurons against oxidative injury induced by cypermethrin.

Added value in stroke imaging: accuracy and utility of additional coronal diffusion-weighted imaging

AIM

To evaluate the value of adding additional coronal diffusion-weighted imaging with the same section thickness as standard axial images to improve detection of small infarcts.

MATERIALS AND METHODS

Axial and coronal diffusion-weighted images (4 or 5 mm section thickness, 1 mm gap) were studied retrospectively in two rounds of data collection. During the first round, two radiologists identified sub-centimetre infarcts on only axial images during one sitting, and only coronal images during a second sitting. During the second round, the two radiologists were asked to identify infarcts on only axial images during one sitting, and on both axial and coronal images simultaneously during the second sitting. An expert reviewer determined true infarcts and artefacts. Relative contrast-to-noise ratios (rCNR) and relative mean region of interest (rROI) within each lesion were calculated.

RESULTS

During the first round, sensitivity for infarct detection for the two radiologists was 92.7% and 100% on axial and 95.1% and 92.7% on coronal, respectively. During the second round, sensitivity improved from 88.9% to 98.1% for both radiologists (p=0.03). Specificity improved but did not reach statistical significance (p=0.06 and 0.12). False-negative and false-positive lesions had lower rCNR and rROI values.

CONCLUSION

Including both axial and coronal DWI images with the same section thickness in the stroke protocol improves detection of small infarcts, which can be misdiagnosed on a single imaging plane. A second imaging plane is particularly useful for subtle infarcts, even without acquiring thin-section images.

[A multicenter retrospective study on the etiology of necrotizing pneumonia in children]

Objective: To investigate the etiology of necrotizing pneumonia (NP) in children and the clinical characteristics of NP caused by different pathogens in China. Methods: A retrospective, case-control study was performed in children with NP who were admitted to 13 hospitals in China from January 2008 to December 2019. The demographic and clinical information, laboratory data, etiological and radiological findings were analyzed. The data were divided into three groups based on the following years: 2008-2011, 2012-2015 and 2016-2019, and the distribution characteristics of the pathogens in different period were compared. Meanwhile, the pathogens of pediatric NP in the southern and northern China were compared. And the clinical characteristics of the Mycoplasma pneumoniae (MP) NP and the bacterial NP were also compared. T-test or Mann-Whitney nonparametric test was used for comparison of numerical variables, and χ² test was used for categorical variables. Results: A total of 494 children with NP were enrolled, the median ages were 4.7 (0.1-15.3) years, including 272 boys and 222 girls. Among these patients, pathogens were identified in 347 cases and the pathogen was unclear in the remaining 147 cases. The main pathogens were MP (238 cases), Streptococcus pneumoniae (SP) (61 cases), Staphylococcus aureus (SA) (51 cases), Pseudomonas aeruginosa (13 cases), Haemophilus influenzae (10 cases), adenovirus (10 cases), and influenza virus A (7 cases), respectively. MP was the most common pathogen in all three periods and the proportion increased yearly. The proportion of MP in 2016-2019 was significantly higher than that in 2012-2015 (52.1% (197/378) vs. 36.8% (32/87), χ²=6.654, P=0.010), while there was no significant difference in the proportion of MP in 2012-2015 and that in 2008-2011 (36.8% (32/87) vs. 31.0% (9/29), χ²=0.314, P=0.575).Regarding the regional distribution, 342 cases were in the southern China and 152 in the northern China. Also, MP was the most common pathogen in both regions, but the proportion of MP was higher and the proportion of SP was lower in the north than those in the south (60.5% (92/152) vs. 42.7% (146/342), χ²=13.409, P<0.010; 7.9% (12/152) vs. 14.3% (49/342), χ²=4.023, P=0.045). Comparing the clinical characteristics of different pathogens, we found that fever and cough were the common symptoms in both single MP and single bacterial groups, but chest pain was more common (17.0% (34/200) vs. 6.1% (6/98), χ²=6.697, P=0.010) while shortness of breath and wheezing were less common in MP group (16.0% (32/200) vs. 60.2% (59/98), χ²=60.688, P<0.01; 4.5% (9/200) vs. 21.4% (21/98), χ²=20.819, P<0.01, respectively). The white blood cell count, C-reactive protein and procalcitonin in the bacterial group were significantly higher than those in the MP group (14.7 (1.0-67.1)×10⁹/L vs. 10.5 (2.5-32.2)×10⁹/L, 122.5 (0.5-277.3) mg/L vs. 51.4 (0.5-200.0) g/L, 2.13 (0.05-100.00) μg/L vs. 0.24 (0.01-18.85) μg/L, Z=-3.719, -5.901 and -7.765, all P<0.01). Conclusions: The prevalence of pediatric NP in China shows an increasing trend during the past years. MP, SP and SA are the main pathogens of NP, and the most common clinical symptoms are fever and cough. The WBC count, C-reactive protein and procalcitonin in bacterial NP are significantly higher than those caused by MP.

Analysis of misses in imaging of head and neck pathology by attending neuroradiologists at a single tertiary academic medical centre

AIM

To analyse errors in head and neck (H&N) pathology made by attending neuroradiologists at a single tertiary-care centre.

MATERIALS AND METHODS

A neuroradiology quality assurance (QA) database of radiological errors was searched for attending physician errors in H&N pathology from 2014-2020. Data were limited to computed tomography (CT) and magnetic resonance imaging (MRI) reports. Data were collected on missed pathologies and study types. Misses were grouped into three categories: central neck (thyroid gland, aerodigestive tract), lateral neck (salivary glands, lymph nodes, soft tissues), and face/orbits (orbits, sinuses, masticator space).

RESULTS

During the study period, a total of 283,248 CT and MRI neuroradiology examinations were interpreted (all indications). Seventy-four H&N misses were identified comprising 85.1% perceptual and 14.9% interpretive errors. The distribution of errors was face/orbits (37.8%), central neck (36.5%), and lateral neck (25.7%). Clinically significant errors were found most commonly in the aerodigestive tract (21%), orbits (17.7%), masticator space, and parotid glands (14.5% each). The majority (67.6%) of the misses were detected on examinations that were not performed for a primary H&N indication; MRI brain was the most common examination (27%). Clearly malignant or potentially malignant masses accounted for 48.6% of all misses.

CONCLUSION

The majority of H&N misses were perceptual and were detected on examinations not performed for a H&N indication. Clearly malignant or potentially malignant masses represented half of all misses.

Peta-electron volt gamma-ray emission from the Crab Nebula

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 × 10³⁶ 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.

Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E>25  TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160  TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10¹⁵ 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 rays¹. 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. ²). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane^3-6, 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.

Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.

Development of the Soft X-ray AGM-AGS RIXS beamline at the Taiwan Photon Source

We report on the development of a high-resolution and highly efficient beamline for soft X-ray resonant inelastic X-ray scattering (RIXS) located at the Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher-order aberrations, as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum-resolved RIXS measurements with scattering angles over a wide range. Several high-precision instruments developed in-house for this beamline are described briefly. The best energy resolution obtained from this AGM-AGS beamline was 12.4 meV at 530 eV, achieving a resolving power of 4.2 × 104, while the bandwidth of the incident soft X-rays was kept at 0.5 eV. To demonstrate the scientific impact of high-resolution RIXS, we present an example of momentum-resolved RIXS measurements on a high-temperature superconducting cuprate, i.e. La2-xSrxCuO4. The measurements reveal the A1g buckling phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge-density waves.

MicroRNA-448/EPHA7 axis regulates cell proliferation, invasion and migration via regulation of PI3K/AKT signaling pathway and epithelial-to-mesenchymal transition in non-small cell lung cancer

OBJECTIVE

Non-small cell lung cancer (NSCLC) is a primary subtype of lung cancers which has a high morbidity and poor prognosis. Emerging evidence has demonstrated that aberrantly expressed microRNAs (miRNAs) were implicated in the regulatory functions of multiple processes during tumorigenesis. In the current study, we explored the functional roles and underlying mechanisms of miR-448 in NSCLC.

PATIENTS AND METHODS

Quantitative real-time polymerase chain reaction assays were conducted to measure miR-448 expressions in 51 pairs of NSCLC tissues and corresponding normal tissues. Moreover, the relationship between miR-448 expressions and clinicopathological characteristics of NSCLC patients was also determined. We then performed transwell assays to explore the functions of miR-448 in NSCLC cell invasion and migration. As we had identified EPHA7 as a functional target of miR-448 in NSCLC cells, the clinical significance of EPHA7 in NSCLC patients was further investigated. Finally, we detected the influence of miR-448 on tumor growth rate and tumor size of NSCLC using tumor xenografts.

RESULTS

Underexpressed miR-448 was identified in NSCLC, and low miR-448 expression was confirmed to be associated with the poor prognosis and adverse clinicopathologic features of NSCLC patients. Moreover, functional assays demonstrated that miR-448 overexpression suppressed NSCLC cell proliferation, invasion and migration. EPHA7 was identified as a direct target of miR-448. Additionally, miR-448 restoration suppressed in vivo NSCLC cell growth. Finally, our studies also indicated that miR-448 exerted anti-NSCLC functions via regulating PI3K/AKT signaling pathway and EMT.

CONCLUSIONS

These results showed that miR-448/EPHA7 axis maybe one of the useful diagnostic and prognostic biomarkers for NSCLC patients.

Unconventional Transverse Transport above and below the Magnetic Transition Temperature in Weyl Semimetal EuCd_{2}As_{2}

As exemplified by the growing interest in the quantum anomalous Hall effect, the research on topology as an organizing principle of quantum matter is greatly enriched from the interplay with magnetism. In this vein, we present a combined electrical and thermoelectrical transport study on the magnetic Weyl semimetal EuCd_{2}As_{2}. Unconventional contribution to the anomalous Hall and anomalous Nernst effects were observed both above and below the magnetic transition temperature of EuCd_{2}As_{2}, indicating the existence of significant Berry curvature. EuCd_{2}As_{2} represents a rare case in which this unconventional transverse transport emerges both above and below the magnetic transition temperature in the same material. The transport properties evolve with temperature and field in the antiferromagnetic phase in a different manner than in the paramagnetic phase, suggesting different mechanisms to their origin. Our results indicate EuCd_{2}As_{2} is a fertile playground for investigating the interplay between magnetism and topology, and potentially a plethora of topologically nontrivial phases rooted in this interplay.