Causal associations between COVID-19 and Atrial Fibrillation: A bidirectional Mendelian randomization study

BackgroundObservational studies showed that coronavirus disease 2019 (COVID-19) attacks universally and its most menacing progression uniquely endangers the elderly with cardiovascular disease (CVD). Whether COVID-19 is causally related to increasing susceptibility and severity of atrial fibrillation (AF), the main form of CVD, remains still unknown. MethodsThe study aims to investigate the bidirectional causal relations of COVID-19 with AF using two-sample Mendelian randomization (MR) analysis. ResultsMR evidence suggested genetically predicted severe COVID-19 was significantly associated with higher risk of AF (odds ratio [OR], 1.041; 95% confidence interval (CI), 1.007-1.076; P = 0.017), while genetically predicted AF was not causally associated with severe COVID-19 (OR, 0.831; 95% CI, 1.619-1.115; P=0.217). There was limited evidence to support association of genetically proxied COVID-19 with risk of AF (OR, 1.051; 95% CI, 0.991-1.114; P=0.097), and vice versa (OR, 0.163; 95% CI, 0.004-6.790; P=0.341). MR-Egger indicated no evidence of pleiotropic bias. ConclusionOverall, severe COVID-19 may causally affect AF through independent biological pathway. Survivors from severe COVID-19 might be of high risk of AF in the future.

Association of 25 hydroxyvitamin D concentration with risk of COVID-19: a Mendelian randomization study

BackgroundIn observational studies, 25 hydroxyvitamin D (25OHD) concentration has been associated with an increased risk of Coronavirus disease 2019 (COVID-19). However, it remains unclear whether this association is causal. MethodsWe performed a two-sample Mendelian randomization (MR) to explore the causal relationship between 25OHD concentration and COVID-19, using summary data from the genome-wide association studies (GWASs) and using 25OHD concentration-related SNPs as instrumental variables (IVs). ResultsMR analysis did not show any evidence of a causal association of 25OHD concentration with COVID-19 susceptibility and severity (OR=1.168, 95% CI 0.956-1.427; OR=0.889, 95% CI 0.549-1.439). Sensitivity analyses using different instruments and statistical models yielded similar findings, suggesting the robustness of the causal association. No obvious pleiotropy bias and heterogeneity were observed. ConclusionThe MR analysis showed that there might be no linear causal relationship of 25OHD concentration with COVID-19 susceptibility and severity.

The study of tube voltage selection influencing image quality in digital chest radiography / 中华放射学杂志

Objective To study the relationship between the selection of tube tension in digitalchest radiograph and image quality.Methods When tube current was fixed at 4 mAs, the choice of X-ray tube voltage changed from 60 to 120 kV.CDRAD2.0 contrast details phantom and normal human chest were exposed by X-ray system with 7 kinds of tube voltage (the difference between tube voltage was 10 kV) ,and the X-ray incidental dose of phantom surface was measured.Five radiologists with 3 years working experience evaluated the image quality on monitor and calculated the image quality factor (IQF) and image reading score.Statistics analysis was then performed by using ANOVA test and t test.According to the results, the optimum tube voltage range was determined.Results (1) The incidental dose of phantom surface increased with the higher tube voltage.(2)When the tube voltage was changed from 60 kV to 120 kV, the IQF value observed in CDRAD2.0 phantom image on monitor was 75.0±10.4,57.1±6.4,52.7±2.5,47.9±4.5, 46.0±3.8,46.0±2.8,45.2±3.5 ,there was significant statistical differences between groups(F=19.10, P<0.01).(3)The integrated score of the chest image quality in the tube voltage 90 kV and 120 kV were 12.4±0.9 and 13.0±0.7, respectively, and there was no statistical difference between two groups(t= 1.500,P>0.05).Conclusions (1)With the increase of tube tension,the display capacity of display device gradually strengthened.When the tube tension exceeded 90 kV, the increase of image quality on monitor was not evident.(2) With proper radiation dose, the value of tube tension in digital X-ray chest photograph was about 90 kV.

Protein Preparation, Crystallization and Preliminary X-ray Crystallographic Analysis of Smu_195c From Caries Pathogen Streptococcus mutans / 生物化学与生物物理进展

Smu_195c is a protein with 86 amino acids in Streptococcus mutans, a primary pathogen for human dental caries. The specific function of Smu_195c is still unknown and there are no conserved domains in it. In order to find out its function, the gene encodes Smu_195c was cloned and expressed in E. coli as N-terminally 6*His tagged recombinant protein. Two crystal forms were obtained by the hanging drop method. Form Ⅰ belongs to space group P6122 or P6522 with the unit cell parameters a = b = 62.93 (A), c= 90.63 (A), γ=120° and form Ⅱ belongs to the space group P41212 or P43212 with the unit cell parameters a =b=57.97 (A), c = 103.51 (A).Crystals from the protein with His-tag belong to form Ⅰ, however, crystals from the protein without His-tag belong to both.

Expression, Purification, Crystallization and Preliminary X-ray Studies of a Deoxycytidylate Deaminase From Streptococcus mutans / 生物化学与生物物理进展

Deoxycytidylate (dCMP) deaminase is an enzyme belonged to dCMP cyt deam family. The dCMP deaminase from Streptococcus mutans UA159 was cloned and expressed in E. coli, and purified to homogeneity. The FPLC size exclusion chromatography analysis reveals that the S. mutans dCMP deaminase forms hexamer in solution. The protein was crystallized using hanging drop vapour-diffusion method and diffracted to a resolution of 3.1 (A). The diffraction data were collected at BSRF beamline3W1A. The crystals belong to P213 space group, with unit cell parameters a = b = c = 113.2(A), α =β = γ = 90°. Assuming there are two subunits per asymmetric unit, the Matthews coefficient is 3.6 (A)3 ·Da-1. This is the first crystallization report of the wild-type deoxycytidylate deaminase.

Expression,Purification,Crystallization and Preliminary X-ray Studies of a Deoxycytidylate Deaminase From Streptococcus mutans / 生物化学与生物物理进展

Deoxycytidylate (dCMP) deaminase is an enzyme belonged to dCMP cyt deam family. The dCMP deaminase from Streptococcus mutans UA159 was cloned and expressed in E. coli, and purified to homogeneity. The FPLC size exclusion chromatography analysis reveals that the S. mutans dCMP deaminase forms hexamer in solution. The protein was crystallized using hanging drop vapour-diffusion method and diffracted to a resolution of 3.1 ?. The diffraction data were collected at BSRF beamline 3W1A. The crystals belong to P213 space group, with unit cell parameters a = b = c = 113.2 ?, ? = ? = ? = 90?. Assuming there are two subunits per asymmetric unit, the Matthews coefficient is 3.6 ?3?Da-1. This is the first crystallization report of the wild-type deoxycytidylate deaminase.

GINSENOSIDE FACILITATES LEARNING AND MEMORY IN AGED MICE / 营养学报

Objective To investigate the effect of ginsenoside on degeneration of learning and memory in aged mice and the mechanism. Method Eighty female C57BL/6J mice aged 20-mo were randomly divided into control group and three ginsenoside treatment groups at dosage of 25,50,100 mg/(kg bw?d) respectively by drinking. In addition, 20 female C57BL/6J mice aged 3 mo were used to be young control group. Eight mo later, the learning and memory abilities of the mice were checked by Morris water maze. Thereafter, the mice were killed by decapitation,and their serum was collected to determine the level of SOD, GSH-Px and MDA. Hippocampal morphology was examined by Nissl stain; and the expression of brain-derived neurotrophic factor (BDNF) in hippocampus was studied using Western blot method. Results 50,100 mg/(kg bw?d) ginsenosides administration could significantly shorten the escape latency of the aged mice in Morris water maze. Furthermore,the alleviated oxidative stress and up-regulated expression of BDNF were observed in 50, 100 (mg/kg?d) ginsenosides groups compared with aged control group. Serum level of GSH-Px was higher in 25 (mg/kg bw?d) ginsenosides group compared to that of aged control group. The number of Nissl-positive cell had no significant difference between all groups. Conclusion 50,100 mg/(kg bw?d) ginsenoside can significantly delay the degeneration of learning and memory in aged mice by lowering oxidative damage and up-regulating BDNF expression in hippocampus.