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.

[Efficacy and safety of prophylactic intravenous administration of tranexamic acid in abdominal aorta balloon-assisted pelvic tumor surgery]

Objective: To investigate the efficacy and safety of prophylactic intravenous (IV) administration of tranexamic acid (TXA) in abdominal aorta balloon-assisted pelvic tumor surgery. Methods: The data of patients who underwent abdominal aorta balloon-assisted pelvic tumor surgery in Peking University People's Hospital from January 1, 2015 to December 31, 2019 were retrospectively collected. According to whether receiving the prophylactic use of TXA, the patients were divided into two groups: TXA group and control group. After propensity score matching based on age, gender and surgeon, 51 patients in TXA group and 51 patients in control group were allocated. The baseline, intraoperative and postoperative clinical data of the two groups were compared to explore the efficacy and safety of TXA. Results: A total of 525 cases undergoing abdominal aorta balloon-assisted pelvic surgery were enrolled from 2015 to 2019, of which 51 cases received prophylactic use of TXA, with a utilization rate of 9.7%. There were no significant differences in age [(40.7±15.1) years vs (38.2±14.5) years, P=0.393], gender (male: 51.0% vs 49.0%, P=0.843), body weight, body mass index (BMI), complications, American Society of Anesthesiologists (ASA) classification, hemoglobin, hemocrit (Hct), platelet, coagulation function-related indexes and tumor pathological types between the two groups (all P>0.05). Likewise, there were no significant differences in operation time, anesthesia time, cumulative time of balloon occlusion, intraoperative blood loss, intravenous fluid volume and blood transfusion volume between the two groups (all P>0.05). Additionally, there were no significant differences in postoperative ICU admission rate and length of hospital stay between the two groups (all P>0.05), and no venous thromboembolism (VTE) or death was reported. Compared with the control group, the rate of blood transfusion at 24 hours after operation in the TXA group was lower (41.2% vs 70.6%, P=0.003). The level of fibrinogen degradation products was lower [10.4 (6.1, 22.6) mg/L vs 13.2 (7.0, 24.7) mg/L], but the difference was not statistically significant (P=0.326). Conclusions: Prophylactic IV use of TXA does not reduce intraoperative bleeding in abdominal aorta balloon-assisted pelvic tumor surgery, but can decrease the rate of postoperative blood transfusion. No increased risk of postoperative TXA-related VTE was observed.

[Effect of serum lipid level on prognosis of patients with small cell lung cancer at the initial treatment]

Objective: To investigate the effect of serum lipid level on prognosis of patients with small cell lung cancer (SCLC) at the initial treatment. Methods: The clinical data of patients with SCLC from 2012 to 2017 in our hospital were retrospectively analyzed. According to the standard of appropriate level and abnormal stratification of blood lipid in Chinese population, the lipids included total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDLC) and low-density lipoprotein cholesterol (LDLC) at the time of initial treatment were grouped. Then the relationship between different lipid levels and clinicopathological characteristics was analyzed. Finally, Cox proportional hazard model was used to analyze the independent prognostic factors of patients. Results: A total of 129 patients with SCLC were included in this study. At the time of initial treatment, there were 90 (69.8%) cases whose TC < 5.2 mmol/L, while 39 (30.2%) cases ≥5.2 mmol/L; 95 (73.6%) cases whose TG <1.7 mmol/L, while 34 (26.4%) cases ≥1.7 mmol/L; 27 (20.9%) cases whose HDLC <1.0 mmol/L while 102 cases (79.1%) ≥1.0 mmol/L; 90 (69.8%) cases whose LDLC <3.4 mmol/L while 39 cases (30.2%) ≥3.4 mmol/L. The patients' triglyceride initial treatment was associated with their body mass index (P<0.05). The median disease-free survival (PFS) of SCLC patients was related with their serum TC level and clinical stage (P<0.05) and the overall survival (OS) was related with clinical stage of SCLC patients (P<0.05). The median PFS of SCLC patients in the TC <1.7 mmol/L group at the initial treatment was 10.5 months, significantly longer than 8.8 months of the TC ≥1.7 mmol/L group (P=0.024). The median OS of SCLC patients in the TG <1.7 mmol/L group at the initial treatment was 20.2 months, marginally longer than 15.6 months of the TG ≥1.7 mmol/L group (P=0.097). Multivariate analysis result showed that, the TG level was an independent risk factor of SCLC progression at the time of initial treatment (P=0.024). There was no significant correlation of TC, HDLC, LDLC and SCLC prognosis (P>0.05). Conclusion: TG level is an independent risk factor for the progression of SCLC at the time of initial treatment, and the increase of TG level indicates rapid disease progression and poor prognosis.

[Challenges and countermeasures in prevention of re - establishment of imported malaria in China]

Malaria was one for the most serious communicable diseases in China. Following the concerted efforts for decades, remarkable achievements have been gained for malaria control in China. Since the national malaria elimination programme was initiated in China in 2010, local malaria transmission was rapidly interrupted, with zero indigenous malaria case reported for the first time in the country in 2017, and the country will undergo the certification of malaria elimination by WHO. Currently, however, malaria remains hyper-endemic across the world. In China, there are more than 2 000 overseas imported malaria cases each year, and prevention of re-establishment of imported malaria will become the major task in future malaria control activities. Here by, we analyze the main challenges in the prevention of re-establishment of imported malaria in China, and propose the corresponding countermeasures, so as to provide insights into the consolidation of malaria elimination achievements.

Tea Consumption and Depression from Follow Up in the Singapore Longitudinal Ageing Study

OBJECTIVES

Experimental evidence suggest that tea polyphenols have anti-depressant effect and tea consumption may reduce the risk and severity of depression. We investigated whether tea consumption was associated with changes in depressive symptoms over time among Asian older adults.

DESIGN

Population-based prospective cohort study with mean 4 years of follow up.

SETTING

Singapore Longitudinal Ageing Study (SLAS) of community-living older persons.

PARTICIPANTS

3177 participants overall (mean age 67 years) and 3004 participants who were depression-free at baseline.

MEASUREMENTS

Baseline tea consumption which include Chinese (black, oolong or green) tea or Western (mixed with milk) tea and change in Geriatric Depression Scale (GDS) measure of depression. Incident depression was defined by GDS≥5, and GDS depression improvement or deterioration by GDS change of ≥4 points. Estimated odds ratio and 95% confidence intervals (OR, 95%CI) were adjusted for baseline age, sex, ethnicity, education, housing type, single/divorced/widowed, living alone, physical and social activity, smoking, alcohol, number of comorbidities, MMSE, and baseline GDS level.

RESULTS

Compared to non-tea drinkers, participants who consumed ≥3 cups of tea of all kinds were significantly less likely to have worsened GDS symptoms: OR=0.32, 95% CI=0.12, 0.84. Among baseline depression-free participants, the risk of incident GDS (≥5) depression was significantly lower (OR=0.34, 95%CI=0.13, 0.90) for daily consumption of all types of tea, and Chinese (black, oolong or green) tea (OR=0.46, 95%CI=0.21,0.99).

CONCLUSION

This study suggests that tea may prevent the worsening of existing depressive symptoms and the reduce the likelihood of developing threshold depression.

Development, Validation and Field Evaluation of the Singapore Longitudinal Ageing Study (SLAS) Risk Index for Prediction of Mild Cognitive Impairment and Dementia

BACKGROUND

Mild cognitive impairment (MCI) is a critical pre-dementia target for preventive interventions. There are few brief screening tools based on self-reported personal lifestyle and health-related information for predicting MCI that have been validated for their generalizability and utility in primary care and community settings.

OBJECTIVE

To develop and validate a MCI risk prediction index, and evaluate its field application in a pilot community intervention trial project.

DESIGN

Two independent population-based cohorts in the Singapore Longitudinal Ageing Study (SLAS). We used SLAS1 as a development cohort to construct the risk assessment instrument, and SLA2 as a validation cohort to verify its generalizability.

SETTING

community-based screening and lifestyle intervention Participants: (1) SLAS1 cognitively normal (CN) aged ≥55 years with average 3 years (N=1601); (2) SLAS2 cohort (N=3051) with average 4 years of follow up. (3) 437 participants in a pilot community intervention project.

MEASUREMENTS

The risk index indicators included age, female sex, years of schooling, hearing loss, depression, life satisfaction, number of cardio-metabolic risk factors (wide waist circumference, pre-diabetes or diabetes, hypertension, dyslipidemia). Weighted summed scores predicted probabilities of MCI or dementia. A self-administered questionnaire field version of the risk index was deployed in the pilot community project and evaluated using pre-intervention baseline cognitive function of participants.

RESULTS

Risk scores were associated with increasing probabilities of progression to MCI-or-dementia in the development cohort (AUC=0.73) and with increased prevalence and incidence of MCI-or-dementia in the validation cohort (AUC=0.74). The field questionnaire risk index identified high risk individuals with strong correlation with RBANS cognitive scores in the community program (p<0.001).

CONCLUSIONS

The SLAS risk index is accurate and replicable in predicting MCI, and is applicable in community interventions for dementia prevention.

MiR-146a alleviates inflammation of acute gouty arthritis rats through TLR4/MyD88 signal transduction pathway

OBJECTIVE

The aim of this study was to explore the effect of micro-ribonucleic acid (miR)-146a on acute gouty arthritis rats through Toll-like receptor-4/myeloid differentiation factor 88 (TLR4/MyD88) signal transduction pathway.

MATERIALS AND METHODS

A total of 30 clean-grade Sprague-Dawley rats were divided into three groups, including agomiR-146a group (n=10), antagomiR-146a group (n=10) and negative control group (NC, n=10). The model was successfully established via a one-time injection of sodium urate into ankle joint cavity. Subsequently, agomiR-146a (10 μL), antagomiR-146a (10 μL) and normal saline (10 μL) were intrathecally injected into rats in the three groups at 1 h before injection and 12 h, 24 h, 48 h and 72 h after injection, respectively. The ankle joint swelling index, joint dysfunction index and joint inflammation index of rats in the three groups were closely monitored. After 72 h of observation, the rats were euthanized, and synovial tissues were collected from the knee joint. The expression and distribution of nuclear factor-κB (NF-κB) in synovial tissues were detected using the immunohistochemical method. Meanwhile, the expression levels of inflammatory factors, including tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1) and interleukin-6 (IL-6) were detected via enzyme-linked immunosorbent assay. Furthermore, the mRNA and protein expression levels of TLR4 and MyD88 were detected via quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and Western blotting, respectively.

RESULTS

No statistically significant differences in the joint swelling index, joint dysfunction index, joint inflammation index, TLR4 and MyD88 and related inflammatory factors were found between the NC group and antagomiR-146a group. Compared with the NC group, agomiR-146a group showed markedly reduced ankle joint swelling index (p<0.05). Meanwhile, joint landing behavior and inflammatory swelling were significantly relieved in the agomiR-146a group (p<0.05). The mRNA and protein expression levels of TLR4 and MyD88 were remarkably decreased as well (p<0.05). Furthermore, the expression and distribution of NF-κB in synovial tissues of agomiR-146a group was markedly reduced when compared with the NC group (p<0.05). In addition, agomiR-146a group exhibited significantly lower expression levels of inflammatory factors (TNF-α, IL-1 and IL-6) in synovial tissues (p<0.05).

CONCLUSIONS

MiR-146a alleviates joint inflammation of acute arthritis in rats through the TLR4/MyD88/NF-κB signaling pathway, which may become a new therapeutic target.

Effects of RANKL on the proliferation and apoptosis of fibroblast-like synoviocytes in rheumatoid arthritis through regulating the NF-κB signaling pathway

OBJECTIVE

The aim of this study is to investigate the regulatory effects of receptor activator of nuclear factor-kappa B ligand (RANKL) on the proliferation and apoptosis of fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA), and to explore its regulatory mechanism.

MATERIALS AND METHODS

Synoviocytes were primarily cultured in rats of recognized collagen-induced arthritis (CIA) model. Meanwhile, they were induced into FLS models by lipopolysaccharides (LPS). All cells were divided into three groups, including blank group, model group and RANKL inhibitor group. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) in the cells were detected by enzyme-linked immunosorbent assay (ELISA). The proliferation and apoptosis of FLS were detected via 3-(4,5)-dimethylthiazol (-z-y1)-3,5-diphenytetrazoliumromide (MTT) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) was conducted to measure the messenger ribonucleic acid (mRNA) expression levels of nuclear factor-kappa B ligand (NF-κB) and Caspase-3 in FLS. Furthermore, Western blotting was adopted to detect the protein expression levels of NF-κB and Caspase-3 in FLS.

RESULTS

Compared with the blank group, the expression levels of TNF-α and IL-1β in the cells of the model group increased significantly. Cell proliferation rate increased significantly, whereas the cell apoptosis rate decreased remarkably in the model group. Meanwhile, the mRNA and protein levels of NF-κB and Caspase-3 in FLS were significantly up-regulated. Compared with the model group, the levels of TNF-α and IL-1β in cells of RANKL inhibitor group notably declined. Similarly, cell proliferation rate was significantly reduced, whereas the cell apoptosis rate increased significantly. Furthermore, the mRNA and protein levels of NF-κB and Caspase-3 in FLS were evidently down-regulated.

CONCLUSIONS

RANKL inhibitors can inhibit the proliferation and promote the apoptosis of FLS in RA. In addition, its mechanism may be related to the inhibition of NF-κB signaling pathway.

[Research frontiers in precision therapy for liver cancer]

Hepatocellular carcinoma (HCC), a fatal malignancy, is highly prevalent in China. Recently, tremendous achievements have been made in HCC, both in the clinical management and the understanding of cancer biology. The discovery and application of novel serum biomarkers, such as proteins, miRNAs, and cfDNA (cell-free circulating DNA) methylation will facilitate the early management of HCC. Improvements in radiological and computational technology have made the practice of precision liver surgery a true reality. The emergence of novel molecular targeted therapies, immunotherapy and their combinations has significantly prolonged patient survival rate, but the therapeutic breakthroughs are still needed. Integrated multi-omics analysis has broadened our understanding of HCC pathogenesis, providing an unprecedented molecular characterization of HCC and revealing new therapeutic opportunities. Technological innovations and revolutions such as single-cell sequencing, genome editing, and innovative drug research and development will greatly accelerate our understanding of HCC biology and bring new therapeutic opportunities. Nevertheless, HCC is a highly heterogeneous and treatment-refractory malignancy, therefore deep insights into the biology of the disease and novel therapies for HCC remain an unmet medical need.

The effect of maize-alfalfa intercropping on the physiological characteristics, nitrogen uptake and yield of maize

In Northeastern China, the intensive cropping system and increased use of chemical fertilizer has caused severe problems in terms of sustainable agricultural development. Therefore, to improve agricultural sustainability and crop productivity the farming system needs to be modified in the region. A pot experiment was conducted to evaluate the effect of maize-alfalfa intercropping on the physiological characteristics, nitrogen (N) uptake and yield of the maize crops in northeast China in 2017-2018. The study findings showed that intercropping under N fertilization progressively improved the physio-agronomic indices of the maize crop as compared to mono-cropping. The grain yield, 100 seed weight and biomass dry matter of maize crop improved in intercropping when it was practiced with N fertilizer. Furthermore, intercropping with N fertilization increased the chlorophyll content of the maize crop at bell-mouthed, silking, filing and mature stages by 19%, 44%, 12%, and 9% in 2017 and by 23%, 43%, 15%, and 11% in 2018, respectively, as compared with the monocropping system. Unlike monocropping, intercropping with N fertilization increased the photosynthesis rate (14% and 15%), stomatal conductance (74% and 98%) and transpiration rate (74% and 75%) in 2017 and 2018, respectively. However, intercropping reduced intercellular CO₂ (C_i ). Moreover, intercropping with N fertilization increased the maize N content of grain and leaves as well as total N uptake by 49%, 31% and 93% in 2017 and 53%, 34% and 132%, respectively, in 2018 as compared to monocropping. In conclusion, our results suggest that maize-alfalfa intercropping with optimal N fertilization provides a practical method for improving growth, yield and N accumulation in the maize crop.

Transplantation of bone marrow mesenchymal stem cells alleviates spinal cord injury via inhibiting Notch signaling

OBJECTIVE

To analyze the mechanism of action by which the bone marrow mesenchymal stem cells (BMMSCs) repair the spinal cord injury (SCI) in rats via the Notch signaling pathway.

MATERIALS AND METHODS

A total of 75 male rats aged about 12 weeks old were equally divided into group A (sham operation group), group B (model group), and group C (model group + BMMSCs). The SCI model was established by Allen's method, and the differences in presenilin-1, Hes1 and Notch proteins among the three groups of rats were evaluated via immunohistochemical staining and Western blotting.

RESULTS

Group B exhibited a lower Basso, Beattie, and Bresnahan (BBB) score at each time point than group A and group C (p<0.05), and the BBB score in group C was lower than that in group A (p<0.05). According to the average optical density analysis results of the immunohistochemically stained proteins, the optical density of presenilin-1 protein in group A was lower than that in both group B and group C (p<0.05), and group C exhibited a lower optical density of presenilin-1 protein than group B. In group A, the protein expression of Hes1 in the bone marrow tissues of rats was not evident and weakly positive. Compared with that in group A, it was substantially raised (p<0.05), and the strongly positively expressed Hes1 proteins were yellow or dark brown in group B. Compared with that in group B, the color of Hes1 proteins was lighter (p<0.05), and the positive level of Hes1 proteins was lowered in group C. Group A showed inconspicuously positively expressed Notch proteins, group B brown active Notch proteins, while group C several brown Notch proteins. The optical density of Notch proteins in group A was overtly lower than that in group B and group C (p<0.05), and it was significantly lower in group C than that in group B (p<0.05). Additionally, group B had an evidently higher expression level of Notch proteins than the other two groups (p<0.05), and the expression level of Notch proteins in group C was a little higher than that in group A (p<0.05).

CONCLUSIONS

BMMSCs inhibit the Notch signals to promote the proliferation and differentiation of rat neurons, thereby repairing spinal neurons.

A higher level of total bile acid in early mid-pregnancy is associated with an increased risk of gestational diabetes mellitus: a prospective cohort study in Wuhan, China

PURPOSE

To assess the longitudinal associations between maternal total bile acid (TBA) levels during early mid-pregnancy and the subsequent risk of gestational diabetes mellitus (GDM).

METHODS

In a prospective cohort study, pregnant women who were enrolled prior to gestational week 16 were followed until delivery. TBA levels were tested during weeks 14-18 of gestation. Using logistic regression, we analyzed the associations between quartiles of TBA and GDM based on a 75-g oral glucose tolerance test (OGTT) at 24-28 gestational weeks.

RESULTS

The GDM rate was 7.9% (114/1441). The mean TBA level was higher in women with GDM than in those without GDM (2.1 ± 2.0 vs 1.5 ± 1.0 µmol/L, P = 0.000). The highest TBA level quartile (2.1-10.7 µmol/L) had a 1.78-fold (95% CI 1.01, 3.14) increased risk of GDM compared with that of the lowest quartile (0.0-0.8 µmol/L) after adjusting for pre-pregnancy body mass index (BMI), gestational, age at TBA test and other confounders. High TBA levels were involved in the fasting glucose level rather than that at 1 h and 2 h after OGTT in all participants.

CONCLUSIONS

Pregnant women with higher serum TBA levels during early mid-pregnancy have a higher risk of developing GDM. TBA may be a new risk factor for GDM.