Abstract MP08: Whole Exome Sequencing Study Identified A Novel Variant For Kidney Function And Progression Of Chronic Kidney Disease

Introduction: Most genetic variants for chronic kidney disease (CKD) have been identified in non-coding regions, with functional roles that are difficult to interpret.

Hypothesis: A whole exome sequencing study focusing on coding variants will reveal novel mechanisms of kidney function and CKD.

Methods: We performed whole exome sequencing analyses of cystatin C among 29,789 UK Biobank (UKB) participants with further confirmation among 4,297 white and 607 African American participants of the Health and Retirement Study (HRS). Conditional analyses for loci achieving exome-wide significance ( P <3.5х10 -7 ) were conducted in UKB using both the exome (n=29,789) and imputed GWAS data (n=295,122). Genomic findings were tested for relevance to baseline estimated glomerular filtration rate (eGFR) and stringently adjudicated CKD progression events among participants of the Chronic Renal Insufficiency Cohort (CRIC) by race and smoking status, using a base model and a full model ( Table ).

Results: We identified a common missense variant, CST9 rs2983640, in a previously reported locus ( CST3 intron rs13038305), of which the minor G allele was associated with lower serum cystatin C level (UKB: beta=-0.03 mg/L, P =7.64х10 -92 ; HRS whites: beta=-0.05 mg/L, P =4.71х10 -6 ; HRS African Americans: beta=-0.03 mg/L, P =0.64; and multi-ethnic meta-analysis beta=-0.03 mg/L, P =2.46х10 -91 ). After controlling for the CST3 variant, the G allele was associated with higher cystatin C level (UKB exome: beta=0.003 mg/L, P =0.04; UKB GWAS: beta=0.003 mg/L, P =1.47х10 -10 ). Similar associations were identified in white CRIC participants (direct effect: beta=-0.05 mg/L, P =0.005; conditional effect: beta=0.004 mg/L, P =0.86). The CST9 rs2983640 G allele was associated with lower baseline eGFR (base model beta=-0.33 ml/min/1.73 m 2 , P =1.98х10 -6 ) and higher hazard of developing CKD progression independent of the reported CST3 variant ( Table ).

Conclusions: We identified a novel missense variant influencing cystatin C level and CKD progression.

A multicolor DNA tetrahedron nanoprobe for analyzing human telomerase in living cells

Herein, we report the in situ analysis of human telomerase by a multicolor DNA tetrahedron nanoprobe. The elongated telomeric repeats can hybridize with settled molecular beacons in order, accompanied by sequentially lighted up fluorescence. Imaging telomerase activity, real-time monitoring telomerase action and determining product length distribution in living cells are realized. It detects multiple information of intracellular telomerase and provides deeper insights into the function of telomerase.

[The value of adenosine triphosphate in CD4(+)T lymphocytes in predicting repeated respiratory tract infections in silicosis patients]

Objective: To explore the value of the concentration of adenosine triphosphate (ATP) in CD4(+)T lymphocytes in predicting repeated respiratory tract infections (RRTI) in silicosis patients. Methods: In April 2020, 614 silicosis patients admitted from March 2016 to March 2018 were included in the study, and they were divided into the RRTI group (n=105) and the non RRTI group (n=509) according to whether the occurrence of RRTI, another 30 healthy cases taken from body check were served as control group, and the concentrations of ATP produced by CD4(+)T lymphocytes was measured by ImmuKnow assay, and were compared between the three groups. And drawed the receiver operating characteristic (ROC) curve, and the Logistic regression analysis was used to explore the risk factors of RRTI. Results: The incidence of RRTI in silicosis patients was 17.10% (105/614) . The concentration of ATP produced by CD4(+)T lymphocytes in the RRTI group [ (260.42±90.36) mg/L] was significantly lower than that in the non RRTI group [ (413.66±138.74) mg/L] (t=-10.849, P<0.01) . The area under the ROC curve was 0.834, the cutoff value was 284 mg/L, the sensitivity was 0.88, and the specificity was 0.83. Logistic regression analysis showed that the concentration of ATP produced by CD4(+)T lymphocytes≤284 mg/L, impaired pulmonary ventilation function, serum albumin<40 g/L and diabetes were the risk factors of RRTI in silicosis patients (OR=2.126, 1.217, 1.164, 1.125, P<0.05) . Conclusion: Low CD4(+)T lymphocyte ATP value was a risk factor of RRTI in silicosis patients, and can predict the risk of RRTI in patients with silicosis.

SERS and fluorescence detection of circulating tumor cells (CTCs) with specific capture-release mode based on multifunctional gold nanomaterials and dual-selective recognition

Herein, a dual-selective recognition and multi-enhanced surface-enhanced Raman scattering (SERS)-fluorescence dual mode detection platform is designed for the detection of circulating tumor cells (CTCs). The gold nanoflowers (AuNFs) substrate was synthesized and the CTCs were captured on the surface area of AuNFs/ITO substrate by aptamers modified. At the same time, the novel nanoprobe was designed, anti-EpCAM (AE) and trigger DNA were modified onto the surface of gold nanostars (AuNSs) through a PEG linker. The novel nanoprobe identified CTCs through the specific recognition reaction between AE and the cell epithelial adhesion molecule of the CTCs. The dual-recognition cellular mechanism of the aptamers and AE improves selectivity. Then, the complementary sequence (CS) hybridize with aptamers to release the captured CTCs into the culture medium. The number of CTCs released was detected by SERS and fluorescence. The limit of SERS detection was 5 cells/mL with a linear relationship from 5 to 200 cells/mL. The limit of fluorescence detection was 10 cells/mL with a linear relationship from 10 to 200 cells/mL. Thus, the developed CTCs detection platform demonstrates promising applications for clinical diagnosis.

Decreased hemoglobin as a quantifiable indicator of renal arterial embolization in post-percutaneous nephrolithotomy hemorrhage

To determine quantifiable indicators for post-percutaneous nephrolithotomy (PCNL) renal arterial embolization. A total of 2043 patients who underwent PCNL from September 2012 to March 2018 were reviewed retrospectively. Post-operative hemorrhage patients were extracted and divided into two groups according to treatment methods (conservative methods or super-selective renal arterial embolization [SRAE]). Demographic characteristics and hemorrhage outcomes were compared between the two groups by univariable analysis. Multivariable logistic regression was used to reveal the association between hemorrhage outcome factors and SRAE. A receiver operating characteristic (ROC) curve was drawn to determine the optimized cut-off value for SRAE. We identified 71 patients who had post-PCNL hemorrhage. Seventeen and 54 patients comprised the SRAE and conservative groups, respectively. No significant differences in demographic characteristics were found between the two groups. Univariate analysis showed that the differences in decreased hemoglobin (Hb), hemorrhage types, and transfusion were significant between the two groups (p < 0.001). Multivariable analysis showed that the decreased Hb was closely associated with the risk of SRAE. The ROC curve showed that an adjusted Hb decrease of 3.45 g/dL was an optimum indicator (AUC = 0.925). Decreased Hb is an indicator for SRAE after PCNL. When the adjusted decrease in Hb is ≥ 3.45 g/dL, SRAE should be performed regardless of the manifestations of hemorrhage.

The U-shaped association of altitudes with prevalence of hypertension among residents in Tibet, China

We aimed to evaluate the association of altitudes with the prevalence of hypertension among residents aged 15 years and above in Tibet, China. Data for 11,407 Tibetan residents from the National Health Services Survey in 2013 were analyzed. Association between altitudes and prevalence of physician-diagnosed hypertension was assessed by two logistic regression models as follows: (i) a base model adjusted for age and gender, and (ii) a full model additionally adjusted for body mass index, education, marital status, area of residence, distance to the nearest medical institute, smoking, drinking, and exercise. Nonlinear relationship between altitudes and prevalence of hypertension was explored by restricted cubic spline analyses. Sensitivity analyses were conducted by restricting to residents of rural and/or nomadic areas. The prevalence of hypertension was estimated to be 37.6%. We found a U-shaped association between altitudes and prevalence of physician-diagnosed hypertension with a turning point at around 3800 m (12,467 ft). For residents living above 3800 m, a 1000 m increase in altitudes was associated with 2.05 (95% confidence interval [CI]: 1.62-2.61) times higher odds of having physician-diagnosed hypertension, after adjusting for age and gender. When further controlling for all covariates, the odds ratio (OR) dropped to 1.87 (95% CI: 1.46-2.41). For residents living below 3800 m, a 1000 m increase was associated with 0.29 (95% CI: 0.19-0.44) times less likelihood of having physician-diagnosed hypertension in the full model. Sensitivity analyses among residents in rural and/or nomadic areas showed similar associations. To conclude, altitudes were in a U-shaped association with prevalence of hypertension.

P1381Improved outcome in ablation of ventricular tachycardia in patients with structural heart disease under general anaesthetic

Background

Catheter ablation is an important adjunct to device implantation for secondary prevention of ventricular tachycardia (VT). However, several factors may influence the success of ablations in terms of long-term freedom from VT recurrence. A thus far little examined factor is the use of general anaesthetic (GA) versus conscious sedation during the procedure, which has been shown to improve outcomes in persistent atrial fibrillation (AF) ablation.

Methods

Patients with structural heart disease VT undergoing ablations from January 2015 to March 2019 were retrospectively followed up at a single centre. End points were recurrent VT or device therapy (shock or anti-tachycardia pacing) at one year. Hazard ratios (HR) were generated using a multivariate Cox-regression proportional hazards model including variables of age at ablation, sex, amiodarone use at time of ablation, scar age, left ventricular ejection fraction, use of GA, and diagnosis of: diabetes mellitus (DM), hypertension (HTN), renal impairment or AF.

Results

79 patients (74 male, mean age 68.2+/- 10.3 years) were included. A substrate-based strategy of late potential ablation was employed. 69 had ischaemic and 10 had non-ischaemic cardiomyopathy. Mean scar age was 13.8 +/- 9.8 years; EF was 40-50% in 27 patients, 30-40% in 26 and &lt; 30% in 26. 37 patients had implantable cardioverter defibrillators and 30 had cardiac resynchronisation therapy (CRT) defibrillator devices, 1 had a CRT- pacemaker device and 4 had dual chamber pacemakers. Comorbidities were: DM (16), HTN (31), renal impairment (13), AF (31). 62 patients (79.5%) were on amiodarone at the time of ablation. Mean procedure duration was 234.8 +/- 44.5 min and mean radiofrequency energy application time was 2247 +/- 862 s. 61 were first procedures and 18 were repeat procedures. One patient suffered a complication of groin haematoma. 62 patients (78.5%) underwent VT ablation under GA and 17 (21.5%) under sedation of midazolam and fentanyl. Patient characteristics did not differ between groups. Significant factors which increased freedom from VT recurrence or device therapy were HTN (88.9% vs 59.4%, HR 0.72, 95% confidence interval (CI): 0.007-0.75, p= 0.028), amiodarone treatment (50.0% vs 76.3%, HR 0.036, 95% CI: 0.003-0.404, p = 0.036) and ablation under GA rather than sedation (50.0% vs 75.0%, HR 0.055, 95% CI: 0.006-0.495, p = 0.01) (Fig 1).

Conclusions

In patients with structural heart disease undergoing VT ablation, outcomes are improved with the use of GA over conscious sedation.

Abstract Figure 1

Association of Low to Moderate Alcohol Drinking With Cognitive Functions From Middle to Older Age Among US Adults

IMPORTANCE

Studies examining the association of low to moderate drinking with various cognitive functions have yielded mixed findings.

OBJECTIVE

To investigate whether associations exist between low to moderate alcohol drinking and cognitive function trajectories or rates of change in cognitive function from middle age to older age among US adults.

DESIGN, SETTING, AND PARTICIPANTS

A prospective cohort study of participants drawn from the Health and Retirement Study (HRS), a nationally representative sample of US adults, with mean (SD) follow-up of 9.1 (3.1) years. In total, 19 887 participants who had their cognitive functions measured in the HRS starting in 1996 through 2008 and who had participated in at least 3 biennial surveys were included. The data analysis was conducted from June to November 2019.

EXPOSURES

Alcohol consumption and aging.

MAIN OUTCOMES AND MEASURES

Trajectories and annual rates of change for the cognitive domains of mental status, word recall, and vocabulary and for the total cognitive score, which was the sum of the mental status and word recall scores. Participants were clustered into 2 cognitive function trajectories for each cognition measure assessed based on their scores at baseline and through at least 3 biennial surveys: a consistently low trajectory (representing low cognitive scores throughout the study period) and a consistently high trajectory (representing high cognitive scores throughout the study period).

RESULTS

The mean (SD) age of 19 887 participants was 61.8 (10.2) years, and the majority of the HRS participants were women (11 943 [60.1%]) and of white race/ethnicity (16 950 [85.2%]). Low to moderate drinking (<8 drinks per week for women and <15 drinks per week for men) was significantly associated with a consistently high cognitive function trajectory and a lower rate of cognitive decline. Compared with never drinkers, low to moderate drinkers were less likely to have a consistently low trajectory for total cognitive function (odds ratio [OR], 0.66; 95% CI, 0.59-0.74), mental status (OR, 0.71; 95% CI, 0.63-0.81), word recall (OR, 0.74; 95% CI, 0.69-0.80), and vocabulary (OR, 0.64; 95% CI, 0.56-0.74) (all P < .001). In addition, low to moderate drinking was associated with decreased annual rates of total cognitive function decline (β coefficient, 0.04; 95% CI, 0.02-0.07; P = .002), mental status (β coefficient, 0.02; 95% CI, 0.01-0.03; P = .002), word recall (β coefficient, 0.02; 95% CI, 0.01-0.04; P = .01), and vocabulary (β coefficient, 0.01; 95% CI, 0.00-0.03; P = .08). A significant racial/ethnic difference was observed for trajectories of mental status (P = .02 for interaction), in which low to moderate drinking was associated with lower odds of having a consistently low trajectory for white participants (OR, 0.65; 95% CI, 0.56-0.75) but not for black participants (OR, 1.02; 95% CI, 0.74-1.39). Finally, the dosage of alcohol consumed had a U-shaped association with all cognitive function domains for all participants, with an optimal dose of 10 to 14 drinks per week.

CONCLUSIONS AND RELEVANCE

These findings suggested that low to moderate alcohol drinking was associated with better global cognition scores, and these associations appeared stronger for white participants than for black participants. Studies examining the mechanisms underlying the association between alcohol drinking and cognition in middle-aged or older adults are needed.

Characterization and Analysis of Collective Cellular Behaviors in 3D Dextran Hydrogels with Homogenous and Clustered RGD Compositions

The interactions between substrate materials and cells usually play an important role in the hydrogel-based 3D cell cultures. However, the hydrogels that are usually used could not be parametrically regulated, especially for quantitatively regulating the spatial distribution of the adhesion sites for cells in 3D. Here, we employed the semisynthetic hydrogel consisting of maleimide-dextran, Arg-Gly-Asp (RGD) peptides, and cell degradable crosslinkers to biochemically characterize the evolutionary behaviors of NIH-3T3 fibroblasts and C2C12 cells in 3D. Moreover, by comparing the cell-adhesive efficacy of 3D dextran hydrogels with four different RGD clustering rates, we explored the underlying regulation law of C2C12 connections and 3T3 aggregations. The results showed that mal-dextran hydrogel could promise cells stable viability and continuous proliferation, and induce more self-organized multicellular structures relative to 2D culture. More importantly, we found that RGD-clustered mal-dextran hydrogel has the advantage of enhancing C2C12 cell elongation and the breadthwise-aggregated connection, and promoting the 3T3 cell aggregating degree compared to that with homogenous RGD. Further, the advantages of RGD clustering hydrogel could be amplified by appropriately reducing RGD concentration. Such RGD-composition controllable mal-dextran hydrogel can function as a regulator of the collective cellular behaviors, which provides useful information for quantitatively designing the tailored hydrogel system and exploiting advanced biomaterials.

Abstract 139: Nicotinic Acetylcholine Receptor Genes Contribute to Leptin Resistance

Background: The mechanisms of leptin resistance among overweight/obese individuals in not fully understood. Smokers have lower body mass index (BMI) compared to non-smokers, and quit smoking results in weight gain. Therefore, we aimed to evaluate whether smoking related genes contribute to leptin resistance.

Methods: A total of 541 SNPs in seven genes of the nicotinic acetylcholine receptors family ( CHRNB2-B4, CHRNA3-A6 ) were evaluated for interactions with leptin on BMI among 748 European American participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Significant SNPs were evaluated for replication among 3,844 participants of the Framingham Heart Study (FHS) 3 rd generation cohort. Multivariate linear regressions were used in single SNP-based analyses controlling for age and sex. Gene-based analyses were performed using the GATES method. MESA and FHS results were combined through meta-analysis methods.

Results: After Bonferroni correction, a total of 34 SNPs within genes CHRNA3 , CHRNA5 , CHRNA6 , CHRNB2, and CHRNB3 significantly ( P <8.20х10 -4 , correcting for 61 linkage disequilibrium blocks) interacted with leptin on BMI, of which, 23 SNPs reached genome-wide significance ( P <5.00х10 -8 ), and 34 SNPs were successfully replicated in the FHS. CHRNB2 rs2072661 (minor allele frequency=0.24) was most significant with a major G allele negatively interacting with leptin on BMI (MESA: β=-0.05, p=8.20х10 -4 ; FHS: β=-0.05, p=1.31х10 -11 ; Meta: β=-0.05, p=4.19х10 -16 ), indicating that individuals with the major alleles were less resistant to leptin. Meanwhile, gene-based analysis revealed that the seven genes were all significantly interacting with leptin on BMI with meta-analysis p values ranging from 2.62х10 -13 for CHRNB2 to 4.25х10 -5 for CHRNA4 .

Conclusion: Nicotine acetylcholine receptor genes modify the sensitivity of leptin on BMI.

[Application of mendelian randomization methods in causal inference of observational study]

Mendelian randomization (MR) approach follows the Mendel's law of inheritance, which is called "Parental alleles randomly assigned to the offspring", and refers to use genetic variants as an instrumental variable to develop causal inference between the exposure factor and the outcome from observational study. In recent years, with the rapid development of genome-wide association study (GWAS) and various omics data,the disclosure of a large number of aggregated data provides an opportunity for the wide application of MR approach in causal inference. We introduce three methods widely used in MR and then apply them to explore causal relationship between blood metabolites and depressive. The advantages and disadvantages of three methods in causal inference are compared in order to provide reference for the application of MR in observational studies.

Early-life exposure to severe famine is associated with higher methylation level in the IGF2 gene and higher total cholesterol in late adulthood: the Genomic Research of the Chinese Famine (GRECF) study

Objective

To evaluate the association of early-life exposure to the Chinese Great Famine (1959–1961) with DNA methylation in IGF2 and its subsequent influence on blood lipid levels in late adulthood among participants of the Genomic Research of the Chinese Famine (GRECF) study.

Methods

The GRECF study recruited 790 participants born between 1956 and 1964 from 2 neighbor provinces, Anhui and Jiangxi, in China through a multistage, clustered, random sampling. The current study included a random sample of 188 GRECF participants. IGF2 differential methylation region (DMR) is an intragenic DMR located upstream of the imprinted promoters of IGF2 exon 3. DNA methylation were quantified at 8 cytosine-phosphate-guanine dinucleotides (CpG) sites at the IGF2 DMR (chr11p15.5) using the Sequenom EpiTYPER method and the MassARRAY system. Multivariate linear regressions were used to evaluate pairwise associations among famine severity, DNA methylation in the IGF2 gene, and lipid levels. We controlled for age and sex in the base model and additionally controlled for education, smoking, and drinking status in the fully adjusted model. Mediation analysis was applied to assess the mediation effect of DNA methylation at the IGF2 gene on the association between early-life exposure to severe famine and adult lipid levels.

Results

Exposure to severe famine was associated with elevated methylation at CpG1 (chr11: 2126041, build 36) of the IGF2 DMR (β = 0.07; P = 0.0008) and total cholesterol (β = 0.72; P = 1.09 × 10⁻⁷). After adjustment for age and sex, each unit increase in methylation of the CpG1 site was associated with 1.09-unit increase in total cholesterol (P = 0.03). After further adjustment for all covariates, these associations were still significant (P_famine-CpG1 = 0.002, P_{famine-total cholesterol} = 1.28 × 10⁻⁶, and P_{CpG1-total cholesterol} = 0.05).

Conclusion

Increased methylation level in the IGF2 gene was associated with early-life exposure to severe famine, and this change was also positively associated with total cholesterol in late adulthood.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0676-3) contains supplementary material, which is available to authorized users.

[Estimation on the individual treatment effect among heterogeneous population, using the Causal Forests method]

Objective: This project aimed to explore the effectiveness of estimating individual treatment effect on real data, among the heterogeneous population, with Causal Forests (CF) method, to find out the characteristics of heterogeneous population. Methods: We designed and conducted four computer simulation schemes to verify the effect of estimating on individual treatment, using the CF under four different environments of the treatment effects. Real data was then analyzed for the catheterization on right heart. Results: Results from the simulation process showed that the values on individual treatment effect that were estimated by causal forests were consistent with the population effect as well as in line with the expected distribution under the setting of four different effect values. Results of real data analysis showed that values of individual treatment effect among most patients appeared positive, so the use of RHC could cause an increase of the '180-day mortality rate' in the sampled population. Patients with lower predicted probability of 2-mo survival and albumin were more likely to have a lower risk of death after using the RHC. Conclusion: CF method could be effectively used to estimate the individual treatment effect and helping the individuals to make decision on the receipt of treatment.

A DNA walker powered by endogenous enzymes for imaging uracil-DNA glycosylase activity in living cells

A DNA walker powered by endogenous enzymes detects uracil-DNA glycosylase activity in living cells.

The inhibition effect and deactivation mechanism of H2O and SO2 on selective catalytic oxidation of NO over the Mn–Ca–Ox–(CO3)y catalyst

H₂O and SO₂ had an inhibition effect on NO oxidation. SO₂ increased the particle size of the catalyst. H₂O decreased the particle size of the catalyst.