Refining prediction of stroke in sinus node dysfunction patients without atrial fibrillation using a P-combined score: a multi-centre study.

AIMS: Isolated sinus node dysfunction (ISND) is a sinus node dysfunction without atrial fibrillation. A high risk of ischaemic stroke (IS) has been reported in ISND populations. However, current guidelines do not recommend anticoagulation in ISND management. P-wave indicates ISND-related atrial remodelling. P-wave indices and the CHA2DS2-VASc score may contribute to risk stratification for ISND-related IS. METHODS AND RESULTS: In this multi-centre longitudinal cohort, ISND patients were divided into development (n = 1185) and external validation (n = 988) cohorts. Ischaemic stroke prediction capacity of the P-combined score was assessed with regard to discrimination, calibration, and clinical effectiveness. The cut-off value of the score was confirmed by using a restricted cubic spline curve. One hundred and twenty-four (10.46%) ISND patients developed IS [1.63%/year; 95% confidence interval (CI): 1.49-1.78%/year] after a median 3.02-year follow-up in the development cohort. The P-wave terminal force in electrocardiogram-lead V1 (PTFV1) was the only significantly abnormal P-wave index (adjusted hazard ratio: 2.56; 95% CI: 1.72-3.80). Therefore, we incorporated the PTFV1 with the CHA2DS2-VASc score to generate a P-combined score. For a 5-year IS risk, the P-combined score improved Harrell's C-statistic (95% CI) from 0.678 (0.618-0.738) to 0.716 (0.657-0.774) and 0.747 (0.677-0.816) to 0.808 (0.747-0.868) in the development and validation cohorts, respectively, along with calibration and decision curve analyses. The cut-off value of the score was 3 in the development cohort and well-discriminated in the validation cohort. CONCLUSION: Chinese ISND patients have a higher IS risk than the general population. Compared with the CHA2DS2-VASc score, the PTFV1-combined CHA2DS2-VASc score shows a better risk-stratification capacity for ISND-related IS.

By screening the risk factors of ischaemic stroke for isolated sinus node dysfunction (sinus node dysfunction without atrial fibrillation), we developed and validated a new scoring system­P-combined score, which is a combination of an abnormal P-wave terminal force in electrocardiogram-lead V1 (PTFV1) and the CHA2DS2-VASc score. We constructed the P-combined score in the following way: abnormal PTFV1 (2 points), age (1 point for 65­74 years and 2 points for ≥75 years), sex (1 point for female), congestive heart failure (1 point), hypertension (1 point), diabetes mellitus (1 point), vascular disease (1 point), and thrombotic event (2 points). Based on our analysis, we found that the P-combined score showed a strong performance (with a C-statistic of 0.716 for 5 years), which was better than the CHA2DS2-VASc score (C-statistic of 0.678 for 5 years). We also found that the performance of the P-combined score was rigorous in an independent cohort from two external centres (with a C-statistic of 0.808 for 5 years) and outperformed the CHA2DS2-VASc score (C-statistic of 0.747 for 5 years).

Characterizing nighttime vertical profiles of atmospheric particulate matter and ozone in a megacity of south China using unmanned aerial vehicle measurements.

Daytime atmospheric pollution has received wide attention, while the vertical structures of atmospheric pollutants at night play a crucial role in the photochemical process on the following day, which is still less reported. Focusing on Guangzhou, a megacity of South China, we established an unmanned aerial vehicle (UAV) equipped with micro detectors to collect consecutive high-resolution samples of fine particle (PM2.5), submicron particle (PM1.0), black carbon (BC) and ozone (O3) concentrations in the atmosphere, as well as the air temperature (AT) and relative humidity (RH) within a 500 m altitude during nighttime from Oct. 24th to Nov. 6th, 2018. The measurements showed that PM2.5, PM1.0, and BC decreased with altitude and were influenced by the nighttime shallow planetary boundary layer (PBL) where BC was more accumulated and fluctuated. In contrast, O3 was positively correlated with altitude. Backward trajectory clustering and Pasquill stability classification showed that advection and convection significantly influenced the vertical distribution of all pollutants, particularly particulate matter. External air masses carrying high concentrations of pollutants increased PM1.0 and PM2.5 levels by 145% and 455%, respectively, compared to unaffected periods. The ratio of BC to PM2.5 indicated that local emissions had a minor role in nighttime particulate matter. Vertical transport caused by atmospheric instability reduced the differences in pollutant concentrations at various heights. Geodetector and generalized additive model showed that RH and BC accumulation in the PBL were significant factors influencing vertical changes of the secondary aerosol intensity as indicated by the ratio of PM1.0 to PM2.5. The joint explanation of RH and atmospheric stability with other variables such as BC is essential to understand the generation of secondary aerosols. These findings provide insights into regional and local measures to prevent and control night-time particulate matter pollution.

Decrease in ambient volatile organic compounds during the COVID-19 lockdown period in the Pearl River Delta region, south China.

During the COVID-19 lockdown, ambient ozone levels are widely reported to show much smaller decreases or even dramatical increases under substantially reduced precursor NOx levels, yet changes in ambient precursor volatile organic compounds (VOCs) have been scarcely reported during the COVID-19 lockdown, which is an opportunity to examine the impacts of dramatically changing anthropogenic emissions on ambient VOC levels in megacities where ozone formation is largely VOC-limited. In this study, ambient VOCs were monitored online at an urban site in Guangzhou in the Pearl River Delta region before, during, and after the COVID-19 lockdown. The average total mixing ratios of VOCs became 19.1% lower during the lockdown than before, and those of alkanes, alkenes and aromatics decreased by 19.0%, 24.8% and 38.2%, respectively. The levels of light alkanes (C < 6) decreased by only 13.0%, while those of higher alkanes (C ≥ 6) decreased by 67.8% during the lockdown. Disappeared peak VOC levels in morning rush hours and the drop in toluene to benzene ratios during the lockdown suggested significant reductions in vehicle exhaust and industrial solvent emissions. Source apportioning by positive matrix factorization model revealed that reductions in industrial emissions, diesel exhaust (on-road diesel vehicles and off-road diesel engines) and gasoline-related emissions could account for 48.9%, 42.2% and 8.8%, respectively, of the decreased VOC levels during the lockdown. Moreover, the reduction in industrial emissions could explain 56.0% and 70.0% of the reductions in ambient levels of reactive alkenes and aromatics, respectively. An average increase in O3-1 h by 17% and a decrease in the daily maximum 8-h average ozone by 11% under an average decrease in NOx by 57.0% and a decrease in VOCs by 19.1% during the lockdown demonstrated that controlling emissions of precursors VOCs and NOx to prevent ambient O3 pollution in megacities such as Guangzhou remains a highly challenging task.

Lumbar Puncture in the prone position for Low Birth Weight Neonates.

BACKGROUND: Lumbar puncture in the lateral decubitus position will make the neonates uncomfortable and is likely to cause position change and unstable vital signs, and the application of sedative drugs will cause adverse effects. This study explored a novel method for lumbar puncture in the prone position for low weight neonates. METHODS: The neonates were randomly assigned into the standard position group receiving lumbar puncture in the lateral decubitus position; and the improved position group receiving lumbar puncture in the prone position. The success rate of first time attempts and the overall success rate of lumbar puncture, incidence of adverse effects, NIAPAS scores were collected and compared between these two groups. The difference in success rate and adverse effects incidence rate was analysed through Chi-square. Student's t-test was used for the test of NIAPAS rating. RESULTS: The improved position group had a higher success rate of first attempt and overall success rate, significantly lower incidence of adverse effect and lower NIAPAS scores than those of the standard position group (P<0.05). CONCLUSION: This lumbar puncture in the prone position is safer, more effective, and more comfortable for preterm neonates and those with low birth weight. Thus, this method is worth of further promotion. TRIAL REGISTRATION: Registration number, ChiCTR2100049923; Date of Registration, August 11, 2021; Retrospectively registered.

A quantitative analysis of the driving factors affecting seasonal variation of aerosol pH in Guangzhou, China.

Aerosol acidity is of great interest due to its effects on atmospheric chemical processes and impact on human health; however, the driving factors of aerosol acidity have only been scarcely investigated. This study characterized the aerosol acidity during the wet and dry seasons in Guangzhou, China, and systematically analyzed the seasonal variation and the corresponding driving factors of aerosol acidity followed by the discussion of their impact on gas-aerosol partitioning of NH3 and HNO3. It was demonstrated that the pH of PM2.5 was 0.08 unit lower (more acidic) during wet season than during the dry season and the aerosol acidity varied less in South China than that in North China. Additionally, our results showed that the meteorological parameters including temperature and relative humidity have larger effect on aerosol pH variation than chemical species. Particularly, the lower temperature during dry season had the positive influence (0.38 pH unit) on aerosol pH compared to the wet season; however, the negative effect due to relative humidity (RH) and chemical species resulted in a smaller seasonal variation of aerosol pH between these two seasons. The sensitivity analysis showed that the increase of temperature has negative impact (reducing pH) on aerosol pH with an almost linear relationship, while RH and chemical species represented a two-phase linear and nonlinear effect, respectively. Finally, the calculation of gas-aerosol partitioning indicated that the temperature had the largest influence on the seasonal variation of gas-aerosol partitioning for both HNO3 and NH3 followed by liquid water content and non-ideality, while aerosol acidity imposed the lowest impact, which suggests that all the parameters including meteorological and chemical species should be comprehensively evaluated to devise a PM2.5 control strategy.

Evaluation of factors influencing secondary organic carbon (SOC) estimation by CO and EC tracer methods.

Secondary organic carbon (SOC) is known to account for a substantial fraction of fine-mode carbonaceous aerosol. Owing to a limited understanding of SOC formation processes and the absence of direct measurement methods, SOC concentrations are mostly estimated using a tracer-based method utilizing either elemental carbon (EC) or carbon monoxide (CO) as tracers. The performance of these tracer-based methods depends heavily on accurate determination of the (OC/Tracer)pri value. The minimum R squared (MRS) method is currently recognized as a relatively reasonable tool to determine (OC/Tracer)pri. This study estimated SOC based on the MRS method with EC and CO as tracers, followed by the Monte Carlo method to analyze quantitatively the effects of measurement uncertainty, emission scenario and sample size on SOC estimates. We report here four major findings: i) the concentration of O3 was used as an indicator to atmospheric secondary reaction potential, and it was found that the mass proportion of SOC in total OC estimated by CO as the tracer is more consistent with the seasonality of actual secondary reaction potential; ii) the estimation results are highly sensitive to the measurement uncertainty in different emission scenarios, which leads us to conclude that the CO tracer method is more robust than the EC tracer method due to large inherent uncertainties in current EC measurements; iii) oversimplification of emission scenarios has substantial impacts on the estimated SOC value, and careful evaluation of the interdependence between sources should be performed to minimize this bias; and iv) the estimation bias of SOC can be reduced by increasing the sample size, and the tracer method can be expected to generate robust results for sample sizes over 1000. These findings are important in terms of providing a reference to choose appropriate tracers, emission scenarios and sample sizes for robust estimation of SOC in future studies.

Characterization of diurnal variations of PM2.5 acidity using an open thermodynamic system: A case study of Guangzhou, China.

Aerosol acidity has significant implications for atmospheric processing, and high time-resolution measurements can provide critical insights into those processes. This paper reports diurnal variations of aerosol acidity characterized using an open thermodynamic system in Guangzhou, China. Hourly measurements of PM2.5-associated ionic species and related parameters were carried out during June-September 2013 followed by application of the Extended Aerosol Inorganic Model in open mode to estimate aerosol pH. The model-estimated aerosol pH was 2.4 ±â€¯0.3, and the pH diurnal profile exhibited peaks in the early morning (6 a.m.) and troughs in the afternoon (2 p.m.) that appeared to be constrained by liquid water content (LWC) and free H+. A linear regression model was developed to predict aerosol pH, which performed strongly with 4 variables during daytime (NH4+, Na+, SO42- and RH; R2 = 0.95) and 3 during nighttime (NH4+, SO42- and RH; R2 = 0.91). The effect of aerosol acidity on the partitioning of HNO3, HCl and NH3 was studied based on theoretical considerations and measurement data. The fractions in particulate phase for acidic compounds correlated strongly with pH (R2 = 0.64-0.69) while that for NH3, interestingly, was weak (R2 = 0.17). Analytical expressions were developed to explain these observations and it was concluded that the partitioning of HCl and HNO3 was more sensitive to pH compared to that of NH3. These results are significant in terms of potential atmospheric depletion rates of HCl and HNO3 in the region and stress the need for future studies in this direction.

Elevated levels of granzyme B correlated with miR-874-3p downregulation in patients with acute myocardial infarction.

AIM: Granzyme B could induce apoptosis of target cell in acute myocardial infarction (AMI) and was identified as the target of miR-874-3p by searching the miRNA database. We aim to determine the levels of granzyme B and miR-874-3p as well as assay their correlations or predict powers in AMI. PATIENTS & METHODS: We measured levels of plasma granzyme B and miR-874-3p in 80 AMI patients or 40 healthy controls and assayed their correlations or predicted powers for AMI. RESULTS: Elevated levels of granzyme B (16.71 ± 7.23 ng/l vs 9.27 ± 3.90 ng/l) correlated with miR-874-3p downregulation (0.20- ± 0.17-fold vs 1.00- ± 0.79-fold) in AMI patients. CONCLUSION: Plasma miR-874-3p might target granzyme B and it might be an additional biomarker for AMI.