Plasma amyloid-beta levels and risk of new-onset atrial fibrillation in the general population

Background

Atrial fibrillation (AF) is a major health burden worldwide, with significant sex differences in epidemiology and risk factors. Amyloid-β40 (Aβ40) and Amyloid-β42 (Aβ42), the hallmark of cerebral amyloid angiopathy, have recently been linked to prevalence and prognosis of several cardiovascular outcomes including stroke and coronary heart disease. However, whether these biomarkers are associated with incident AF remains largely unknown.

Purpose

To investigate the associations between plasma concentrations of Aβ40 and Aβ42 with new-onset AF.

Methods

4,134 participants without a history of AF at baseline (from 2002 to 2005) with qualified plasma samples in the Rotterdam Study were included in this study. AF was diagnosed by electrocardiograms, general practitioners' and hospital records. Cox proportional hazards regression models with natural cubic splines were used to assess the linear/nonlinear association between biomarkers and risk of new-onset AF. All models were adjusted for traditional cardiovascular risk factors.

Results

Mean age was 71.3±7.2 years and 2,383 (57.6%) were women. Median follow-up time was 9.2 years. In the fully adjusted model, higher levels of Aβ40 [hazard ratio, 95% confidence interval: 1.16 (1.05–1.28)] and Aβ42 [1.19 (1.09–1.31)], as well as Amyloid-β42 to β40 ratio (Aβ42/40) [1.09 (1.02–1.17)] were significantly associated with incident AF. The observed association between Aβ40 and AF attenuated after mutual adjustment for Aβ42 [1.05 (0.92–1.19)]. In addition, a J-shaped association was found between Aβ40 and AF with the lowest AF risk at Aβ40 values of 212.5 pg/ml.

Conclusions

Both Aβ40 and Aβ42 were independently significantly associated with new-onset AF in the general population independent of cardiovascular risk factors. Findings also suggest a stronger association between AF onset and Aβ42 and AF onset, compared to Aβ40. A nonlinear association was found between Aβ40 and AF, reflecting a substantially increased AF risk among participants with severely increased Aβ40 values.

Funding Acknowledgement

Type of funding sources: None.

Cardiometabolic multimorbidity and lifetime risk of atrial fibrillation among men and women

Background

Atrial fibrillation (AF) is the most common cardiac arrythmia worldwide, with an increased risk of comorbidity, and significant sex differences in pathophysiology and prognosis. Cardiometabolic disorders, including obesity, hypertension, diabetes mellitus, coronary heart disease, stroke, and heart failure commonly coexist with AF. However, the sex-specific patterns and (combined) impact of cardiometabolic disorders on the risk of new-onset AF remains largely unknown.

Purpose

To examine the association between patterns of cardiometabolic multimorbidity and new-onset AF and lifetime risk of AF incidence among men and women.

Methods

4,113 men and 5,432 women free of prevalent AF at baseline (from 1996 to 2008) from the Rotterdam Study were included. AF incidents were assessed by electrocardiograms and general practitioners' and hospital records, and followed up to January 1st, 2014. Sex-specific Cox proportional hazards regression models were used to assess the association between the amount of cardiometabolic disorders and risks of new-onset AF. Models were adjusted for traditional cardiovascular risk factors. Remaining lifetime risk for AF was estimated across the cardiometabolic multimorbidity groups at index ages of 55, 65, and ≥75 years up to age 108.

Results

Mean age at baseline was 65.5±9.4 years. Median follow-up time was 10.8 years. In the fully-adjusted model, a significant association was found between the amount of cardiometabolic disorders and incident AF among women but not men. Compared to women without cardiometabolic disorders, women with 3 (hazard ratios, 95% conference intervals: 2.17 (1.24–3.79)) and ≥4 comorbidities (4.58 (2.22–9.48)) had higher AF risks. The lifetime risk for AF was significantly increased with the number of cardiometabolic disorders among both men and women. At index age of 55 years, the lifetime risks (95% confidence interval) for AF were 25.2% (17.1–33.4), 24.2% (20.0–28.9), 27.1% (23.2–31.0), 30.0% (24.3–35.7) and 34.1% (22.4–45.7), for 0, 1, 2, 3, and ≥4 comorbid cardiometabolic disorders among men, respectively. Corresponding risks were 16.3% (6.68–25.9), 20.3% (16.3–24.3), 27.6% (24.1–31.2), 23.6% (17.8–29.4) and 33.3% (16.0–50.2) among women.

Conclusions

We observed a significant combined impact of cardiometabolic disorders on AF risk, most evidently among women. Participants with cardiometabolic multimorbidity had a significantly increased lifetime risk of AF, especially at a young index age.

Funding Acknowledgement

Type of funding sources: None.

Characterization of a novel and glutaminase-free type II L-asparaginase from Corynebacterium glutamicum and its acrylamide alleviation efficiency in potato chips

Type II L-asparaginase as a pivotal enzyme agent has been applied to treating for acute lymphoblastic leukemia (ALL) and efficient mitigation of acrylamide formed in fried and baked foods. However, low activity, narrow range of pH stability, as well as undesirable glutaminase activity hinder the applications of this enzyme. In our work, A novel type II L-asparaginase (CgASNase) from Corynebacterium glutamicum with molecular mass of about 35 kDa was chosen to express in E. coli. CgASNase shared only 27 % structural identity with the reported L-asparaginase from Helicobacter pylori. The purified CgASNase showed the highest specific activity of 1979.08 IU mg^-1 to L-asparagine, compared with reported type II ASNases in the literature. CgASNase displayed superior stability at a wide pH range from 5.0 to 11.0, and retained about 76 % of its activity at 30 °C for 30 min. The kinetic parameters K_m (Michaelis constant), k_cat (turnover number), and k_cat/K_m (catalytic efficiency) values of 4.66 mM, 79,697.40 min^-1, and 17,102.45 mM^-1 min^-1, respectively. More importantly, CgASNase exhibited strict substrate specificity towards L-asparagine, no detectable activity to l-glutamine. To explore its ability to catalyze L-asparagine, CgASNase was supplied in frying potato chips, which produced the fries with 84 % less acrylamide content compared with no supply. These findings suggest that CgASNase presents excellent properties for chemotherapy against diseases and great potential in the food processing industry.

Characterization and Preliminary Application of a Novel Lipoxygenase from Enterovibrio norvegicus

Lipoxygenases have proven to be a potential biocatalyst for various industrial applications. However, low catalytic activity, low thermostability, and narrow range of pH stability largely limit its application. Here, a lipoxygenase (LOX) gene from Enterovibrio norvegicus DSM 15893 (EnLOX) was cloned and expressed in Escherichia coli BL21 (DE3). EnLOX showed the catalytic activity of 40.34 U mg⁻¹ at 50 °C, pH 8.0. Notably, the enzyme showed superior thermostability, and wide pH range stability. EnLOX remained above 50% of its initial activity after heat treatment below 50 °C for 6 h, and its melting point temperature reached 78.7 °C. More than 70% of its activity was maintained after incubation at pH 5.0–9.5 and 4 °C for 10 h. In addition, EnLOX exhibited high substrate specificity towards linoleic acid, and its kinetic parameters of V_max, K_m, and K_cat values were 12.42 mmol min⁻¹ mg⁻¹, 3.49 μmol L⁻¹, and 16.86 s⁻¹, respectively. LC-MS/MS analysis indicated that EnLOX can be classified as 13-LOX, due to its ability to catalyze C₁₈ polyunsaturated fatty acid to form 13-hydroxy fatty acid. Additionally, EnLOX could improve the farinograph characteristics and rheological properties of wheat dough. These results reveal the potential applications of EnLOX in the food industry.

Designed symmetrical β-hairpin peptides for treating multidrug-resistant salmonella typhimurium infections

The rapid emergence and prevalence of multidrug-resistant salmonellosis lack effective therapies, which causes epidemic health problems and stimulates the development of antimicrobials with novel modes of action. In this research, 10 short symmetrical β-hairpin peptides are synthesized by combining the β-turn of Leucocin-A with recurring hydrophobic and cationic amino acid sequences. Those designed peptides exhibited potent antibacterial activities against drug-susceptible and drug-resistant Salmonella. One of the 10 peptides, WK2 ((WK)₂CTKSGC(KW)₂), displayed best cell selectivity towards Salmonella cells over macrophages and erythrocytes in a co-culture model. Fluorescent measurements and microscopic observations reflected that WK2 exerted its antimicrobial activity through a membrane-lytic mechanism. Moreover, the β-hairpin peptides can bind to endotoxin (LPS) and suppress the production of LPS-induced proinflammatory cytokines in RAW264.7 cells, indicating as a potent anti-inflammatory activity. The preliminary in vivo studies can also demonstrate that WK2 decreased loads of Salmonella in the liver and spleen, mitigated Salmonella-caused inflammation and maintained the integrity of intestinal mucosal surfaces. Ultimately, the results highlight that WK2 is a promising therapeutic agent to prevent multidrug-resistant S. Typhimurium infections in humans and animals.

Lithium chloride promotes neural functional recovery after local cerebral ischaemia injury in rats through Wnt signalling pathway activation

BACKGROUND

Lithium chloride (LiCl) has a significant neuroprotective effect in cerebral ischaemia. However, to date, there is a paucity of evidence on the role of LiCl in neural restoration after brain ischaemia and the signalling pathways involved remain unclear.

MATERIALS AND METHODS

Therefore, to address this gap, the middle cerebral artery occlusion (MCAO) rat model was used to simulate human ischaemia stroke. Male Sprague-Dawley rats were given MCAO for 90 min followed by reperfusion, and Dickkopf-1 (DKK1, 5.0 μg/kg) was administered half an hour before MCAO. Rats were then treated with hypodermic injection of LiCl (2.0 mmol/kg) twice a day for 1 week. After treatment, cognitive impairment was assessed by the Morris water maze test. Neurological deficit score, 2,3,5-triphenyl tetrazolium chloride staining, brain water content, and histopathology were used to evaluate brain damage. Enzyme-linked immunosorbent assay was used to measure oxidative stress damage and inflammatory cytokines. Apoptosis of the hippocampal neurons was tested by western blot. The key factors of Wnt signalling pathway in the ischaemic penumbra were detected by immunofluorescence staining and quantitative real-time polymerase chain reaction.

RESULTS

Current experimental results showed that LiCl treatment significantly improved the impaired spatial learning and memory ability, suppressed oxidative stress, inflammatory reaction, and neuron apoptosis accompanied by attenuating neuronal damage, which subsequently decreased the brain oedema, infarct volume and neurological deficit. Furthermore, the treatment of LiCl activated Wnt signalling pathway. Interestingly, the aforementioned effects of LiCl treatment were markedly reversed by administration of DKK1, an inhibitor of Wnt signalling pathway.

CONCLUSIONS

These results indicate that LiCl exhibits neuroprotective effects in focal cerebral ischaemia by Wnt signalling pathway activation, and it might have latent clinical application for the prevention and treatment of ischaemic stroke.

Anti-toxicogenic fungi and toxin-reducing effects of bacillomycin D in combination with fungicides

Mycotoxins are toxic secondary metabolites produced by fungus including Aspergillus and Fusarium. They can contaminate food and cause major health issues. Bacillomycin D (BD) is a natural antimicrobial lipopeptide generated by Bacillus that has excellent antifungal capabilities, but its high price prevents it from being widely used. Chemically produced and essential oil-based fungicides are also currently the most frequent types. In the study, the effects of combining BD with two types of fungicides on the growth of toxicogenic fungi as well as the generation of deoxynivalenol (DON) and fumonisin B₁ (FB₁) were examined. It was discovered that BD was more effective in suppressing molds than the other two types of fungicides, and it could be combined with synthetic or essential oil-based fungicides to provide a synergistic or additive effect. BD 31.25 μg/mL + Thymol (Thy) 7.81 μg/mL and BD 11.45 μg/mL + Cinnamon oil (Cin) 3.90 μg/mL inhibited F. graminearum, respectively. The combination of BD+Thy and BD+Cin at this concentration considerably reduced 60%-80% spore germination, when DON dropped below 300 ng/L. Furthermore, both combinations suppressed F. moniliforme growth and FB₁ synthesis in a dose-dependent manner at lower concentrations. At an action dose of 2 MIC, FB₁ production might be reduced to less than 100 ng/L. Our findings indicated that BD might interact synergistically with various fungicides, suggesting that it could be useful in the field of antifungal and toxicity reduction in food.

Surfactin effectively improves bioavailability of curcumin by formation of nano-capsulation

To improve the bioavailability of curcumin, surfactin was used to prepare curcumin-loaded nanoemulsions (Cur-NEs). Moreover, the physicochemical properties, digestive characteristics, as well as inhibition activity to Caco-2 cells of Cur-NEs were measured. Furthermore, the morphological analysis revealed that Cur-NEs with 320 mg/L surfactin appeared spherical nanoparticale (23.23 ± 2.86 nm) and uniform distribution. The encapsulation efficiency of Cur-NEs with 320 mg/L surfactin was 97.25 ± 1.28%. Simulated gastrointestinal digestion results indicated that surfactin elevated the sustained-release characteristics and higher bioaccessibility (40.92 ± 2.84%) of curcumin. Besides, Cur-NEs with 320 mg/L surfactin exhibited excellent stability in different temperature, pH and light irradiation. In addition, the inhibition of Cur-NEs with 320 mg/L surfactin to Caco-2 cells was 71.29%. Biochemical analysis showed that Cur-NEs enhanced the activity of lactate dehydrogenase, superoxide dismutase, catalase and glutathione peroxidase, as well as the reactive oxygen species content. RT-PCR and ELISA results also revealed that Cur-NEs inhibited Caco-2 cells through the activated mitochondria-mediated pathway. This study provided a strategy to encapsulate curcumin in nanoparticles with surfactin for improving bioavailability.

P-382 Decrease of serum estradiol prior to human chorionic gonadotrophin administration have an impact on live birth in IVF/ICSI cycles

Study question

Whether decrease of serum estradiol prior to human chorionic gonadotrophin administration have an impact on live birth in IVF/ICSI cycles?

Summary answer

The E2 change before the day of hCG administration had significant correlation with live birth. The live birth rate decreased with decreasing serum E2 level.

What is known already

The objective of this study was to assess the effects of a decrease of estradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration on in vitro fertilization /intracytoplasmic sperm injection (IVF/ICSI) outcomes, including cycles with long, antagonist and micro stimulus protocols.

Study design, size, duration

In this retrospective cohort study, 1303 patients who received IVF/ICSI non-donor treatment were identified. Patients were divided into two groups according to live birth and the characteristics of IVF/ICSI cycles were compared between groups, including baseline infertility parameters, ovarian stimulation characteristics and embryo laboratory manipulation parameters.

Participants/materials, setting, methods

In this retrospective cohort study, 1303 patients who received IVF/ICSI non-donor treatment were identified. Patients were divided into two groups according to live birth and the characteristics of IVF/ICSI cycles were compared between groups, including baseline infertility parameters, ovarian stimulation characteristics and embryo laboratory manipulation parameters. The multivariate logistic regression model was performed to adjust potential confounders and assess correlation between E2 dynamics before hCG administration and live birth.

Main results and the role of chance

Our results revealed that patients without live birth had higher age (32.13 ± 4.33 vs. 30.21 ± 3.71, P < 0.001) and pervious miscarriages (0.57 ± 0.95 vs. 0.46 ± 0.83, P = 0.0295), while had lower number of oocytes retrieved (8.95 ± 4.69 vs. 12.36 ± 5.54, P < 0.001), day of hCG E2 (8269.53 ± 4104.22 vs. 9580.71 ± 3534.11, P < 0.001) and endometrium thickness (10.37 ± 3.66 vs. 11.50 ± 3.40, P < 0.001) compared with patients with live birth. Additionally, the multivariate logistic regression analysis displayed significant impact of serum E2 change on the live birth, and the achievement of live birth [OR (95%CI) 0.81 (0.71, 0.92), P = 0.001] decreased with the decreasing level of serum E2 before hCG trigger day. Estradiol stratification analyses displayed the OR and 95% CI for the association between △E2 and live birth among patients with different levels of estradiol decline (<25%, 25%–50%, 50%–75%, >75%). Compared with the <25% decline and 25%–50% decline groups, the ORs of 50%–75% and >75% decline groups were 1.66 (95% CI: 1.12-2.45, P = 0.012) and 2.00 (95% CI: 1.39-2.89, P < 0.001), respectively, after adjusting potential confounders.

Limitations, reasons for caution

There was concealment of randomization and blinding of outcome assessments reducing the risk of selection and measurement bias.

Wider implications of the findings

In summary, the E2 change before the day of hCG administration had significant correlation with live birth, and the live birth decreased with the decreasing level of serum E2 before hCG trigger day. The patients with a greater decline in the E2 level more likely to had poor clinical outcomes.

Trial registration number

Chi CTR1900026088

Cis-Element Engineering Promotes the Expression of Bacillus subtilis Type I L-Asparaginase and Its Application in Food

Type I L-asparaginase from Bacillus licheniformis Z-1 (BlAase) was efficiently produced and secreted in Bacillus subtilis RIK 1285, but its low yield made it unsuitable for industrial use. Thus, a combined method was used in this study to boost BlAase synthesis in B. subtilis. First, fifteen single strong promoters were chosen to replace the original promoter P43, with PyvyD achieving the greatest BlAase activity (436.28 U/mL). Second, dual-promoter systems were built using four promoters (PyvyD, P43, PaprE, and PspoVG) with relatively high BlAase expression levels to boost BlAase output, with the engine of promoter PaprE-PyvyD reaching 502.11 U/mL. The activity of BlAase was also increased (568.59 U/mL) by modifying key portions of the PaprE-PyvyD promoter. Third, when the ribosome binding site (RBS) sequence of promoter PyvyD was replaced, BlAase activity reached 790.1 U/mL, which was 2.27 times greater than the original promoter P43 strain. After 36 h of cultivation, the BlAase expression level in a 10 L fermenter reached 2163.09 U/mL, which was 6.2 times greater than the initial strain using promoter P43. Moreover, the application potential of BlAase on acrylamide migration in potato chips was evaluated. Results showed that 89.50% of acrylamide in fried potato chips could be removed when combined with blanching and BlAase treatment. These findings revealed that combining transcription and translation techniques are effective strategies to boost recombinant protein output, and BlAase can be a great candidate for controlling acrylamide in food processing.

An endolysin Salmcide-p1 from bacteriophage fmb-p1 against gram-negative bacteria

AIMS

A novel endolysin Salmcide-p1 was developed as a promising candidate of new preservative and a supplement to effective enzyme preparations against gram-negative bacterial contaminations.

METHODS AND RESULTS

Salmcide-p1 was identified by complementing the genomic sequence of a virulent Salmonella phage fmb-p1. Salmcide-p1 of 112 μg ml^-1 could quickly kill Salmonella incubated with 100 mmol l^-1 EDTA, with no haemolytic activity. Meanwhile, Salmcide-p1 had a high activity of lysing Salmonella cell wall peptidoglycan. At different temperatures (4-75°C), pH (4-11) and NaCl concentration (10-200 mmol l^-1 ), the relative activity of Salmcide-p1 was above 60%. At 4°C, the combination of Salmcide-p1 and EDTA-2Na could inhibit the number of Salmonella Typhimurium CMCC 50115 in skim milk to less than 4 log CFU ml^-1 by 3 days, and the number of Shigella flexneri CMCC 51571 was lower than 4 log CFU ml^-1 by 9 days.

CONCLUSIONS

Salmcide-p1 had a wide bactericidal activity against gram-negative bacteria and showed a broader anti-Salmonella spectrum than the phage fmb-p1. The combination strategy of Salmcide-p1 and EDTA-2Na could significantly inhibit the growth of gram-negative bacteria inoculated in skim milk.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacteriophage endolysin as an antibacterial agent is considered to be a new strategy against bacterial contamination.

Structure-Function Analysis of a Quinone-Dependent Dehydrogenase Capable of Deoxynivalenol Detoxification

The pyrroloquinoline quinone (PQQ)-dependent dehydrogenase DepA detoxifies deoxynivalenol (DON) by converting the C3-OH into a keto group. Herein, two crystal structures of DepA and its complex with PQQ were determined, together with biochemical evidence confirming the interactions of DepA with PQQ and DON and revealing a unique tyrosine residue important for substrate selection. Furthermore, four loops over the active site essential for DepA activity were identified, of which three loops were stabilized by PQQ, and the fourth loop invisible in both structures was considered important for binding DON, together constituting a lid for the active site. Preliminary engineering of the loop showed its potential for enzyme improvement. This study provides structural insights into how a PQQ-dependent dehydrogenase is equipped with the function of DON conversion and for the first time shows the necessity of a lid structure for PQQ-dependent dehydrogenase activity, laying foundation for structure-based design to enhance catalysis efficiency.

Women-specific risk factors and risk of incident atrial fibrillation in UK Biobank

Funding Acknowledgements

Type of funding sources: None.

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide and carries a large morbidity and mortality risk. Recent evidence suggests differences in epidemiology and pathophysiology of AF between women and men and underscores a poorer prognosis of AF among women. This calls for further investigation regarding the impact of women-specific risk factors on AF development.

Purpose

To investigate the association between women-specific risk factors and new-onset AF.

Methods

235,191 women (mean [standard deviation] age: 55.7 [8.1] years) free of AF and without a history of hysterectomy and/or bilateral oophorectomy from the UK Biobank were included. Various women-specific risk factors were assessed from 2006 to 2010. Follow-up of new-onset AF occurred through October 2020. Cox proportional hazards analyses were performed to investigate prospective associations between each risk factor and incident AF. Additionally, natural splines were used to identify any potential nonlinear associations.

Results

After a median follow-up of 11.6 (interquartile range: 10.9–12.3) years, 4,629 (2%) women experienced new-onset AF. In fully adjusted models, having experienced irregular menstrual cycle was significantly associated with increased new-onset AF risk [hazard ratio (HR); 95% confidence interval (CI): 1.34; 1.01-1.79]. In addition, nonlinear associations were found between menopausal age, menarcheal age, number of live births, and number of total reproductive years with incident AF. Compared to the reference, early menopause (menopause <45 years of age) or delayed menopause (>60 years) significantly increased risks of incident AF (HR; 95CI: 1.24; 1.10-1.39 and 1.34; 1.01-1.78, respectively). Compared to the reference, both early menarche (menarche ≤11 years) and late menarche (menarche ≥13 years) were associated with AF incidence (HR; 95CI: 1.10; 1.00-1.21 and 1.08; 1.00-1.17, respectively). Compared to women with one or two children, having no children (HR; 95CI: 1.13; 1.04-1.24), or more than six children (HR; 95%CI: 1.67; 1.03-2.70) were associated with higher AF risks. Having reproductive years ≤20 years was significantly associated with incident AF (HR; 95CI: 1.74; 1.07-2.86).

Conclusions

Having experienced early or delayed menopause, early or late menarche, or irregular menstrual cycles conferred higher risks of incident AF among women in the UK Biobank. Interestingly, both nulliparity and multiparity, compared to having one or two children, were associated with an increased AF risk. Our results highlight the importance of knowledge regarding the reproductive history of women in devising screening strategies for AF prevention.