Molecular-level chemical composition of aerosol and its potential source tracking at Antarctic Peninsula

Marine organic aerosols play crucial roles in global climatic systems. However, their chemical properties and relationships with various potential organic sources still need clarification. This study employed high-resolution mass spectrometry to investigate the identity, origin, and transportation of organic aerosols in pristine Antarctic environments (King Sejong Station; 62.2°S, 58.8°W), where complex ocean-cryosphere-atmosphere interactions occur. First, we classified the aerosol samples into three clusters based on their air mass transport history. Next, we investigated the relationship between organic aerosols and their potential sources, including organic matter dissolved in the open ocean, coastal waters, and runoff waters. Cluster 1 (C1), in which the aerosols mainly originated from the open ocean area (i.e., pelagic zone-influenced), exhibited a higher abundance of lipid-like and protein-like organic aerosols than cluster 3 (C3), with ratios 1.8- and 1.6-times higher, respectively. In contrast, C3, characterized by longer air mass retention over sea ice and land areas (i.e., inshore-influenced), had higher lignin- and condensed aromatic structures (CAS)-like organic aerosols by 2.2- and 3.4-times compared to C1. Cluster 2 (C2) has intermediate characteristics between C1 and C3 concerning the chemical properties of the aerosols and air mass travel history. Notably, the chemical properties of the aerosols assigned to C1 are closely related to those of phytoplankton-derived organics enriched in the open ocean. In contrast, those of C3 are comparable to those of terrestrial plant-derived organics enriched in coastal and runoff waters. These findings help evaluate the source-dependent properties of organic aerosols in changing Antarctic environment.

Observational evidence linking ocean sulfur compounds to atmospheric dimethyl sulfide during Icelandic Sea phytoplankton blooms

In two Icelandic Sea spring blooms (May 2018 and 2019) in the North Atlantic Ocean (62.9-68.0°N, 9.0-28.0°W), chlorophyll-a and dimethylsulfoniopropionate (DMSP) concentrations and DMSP lyase activity (the DMSP-to-dimethyl sulfide (DMS) conversion efficiency) were measured at 67 stations, and the hourly atmospheric DMS mixing ratios were concurrently measured only in May 2019 at Storhofdi on Heimaey Island, located south of Iceland (63.4°N, 20.3°W). The ocean parameters for biology (i.e., chlorophyll-a, DMSP, and DMSP lyase activity) were broadly associated in distribution; however, the statistical significance of the association differed among four ocean domains and also between 2018 and 2019. Specifically, the widespread dominance of Phaeocystis, coccolithophores, and dinoflagellates (all rich in DMSP and high in DMSP lyase activity) across the study area is a compelling indication that variations in DMSP-rich phytoplankton were likely a main cause of the variations in statistical significance. For all the ocean domains defined here, we found that the DMS production capacity (calculated using the exposures of air masses to ocean biology prior to their arrivals at Heimaey and the atmospheric DMS mixing ratios of those air masses at Heimaey) was surprisingly consistent with in situ ocean S data (i.e., DMSP and DMSP lyase activity). Our study shows that the proposed computational approach enabled the detection of changes in DMS production and emission in association with changes in ocean primary producers.

Ocean-atmosphere interactions: Different organic components across Pacific and Southern Oceans

Sea spray aerosol (SSA) particles strongly influence clouds and climate but the potential impact of ocean microbiota on SSA fluxes is still a matter of active research. Here-by means of in situ ship-borne measurements-we explore simultaneously molecular-level chemical properties of organic matter (OM) in oceans, sea ice, and the ambient PM_2.5 aerosols along a transect of 15,000 km from the western Pacific Ocean (36°13'N) to the Southern Ocean (75°15'S). By means of orbitrap mass spectrometry and optical characteristics, lignin-like material (24 ± 5 %) and humic material (57 ± 8 %) were found to dominate the pelagic Pacific Ocean surface, while intermediate conditions were observed in the Pacific-Southern Ocean waters. In the marine atmosphere, we found a gradient of features in the aerosol: lignin-like material (31 ± 9 %) dominating coastal areas and the pelagic Pacific Ocean, whereas lipid-like (23 ± 16 %) and protein-like (11 ± 10 %) OM controlled the sympagic Southern Ocean (sea ice-influence). The results of this study showed that the OM composition in the ocean, which changes with latitude, affects the OM in aerosol compositions in the atmosphere. This study highlights the importance of the global-scale OM monitoring of the close interaction between the ocean, sea ice, and the atmosphere. Sympagic primary marine aerosols in polar regions must be treated differently from other pelagic-type oceans.

Measurements of Normalized Differential Cross Sections of Inclusive π^{0} and K_{S}^{0} Production in e^{+}e^{-} Annihilation at Energies from 2.2324 to 3.6710 GeV

Based on electron positron collision data collected with the BESIII detector operating at the BEPCII storage rings, the differential cross sections of inclusive π^{0} and K_{S}^{0} production as a function of hadron momentum, normalized by the total cross section of the e^{+}e^{-}→hadrons process, are measured at six center-of-mass energies from 2.2324 to 3.6710 GeV. Our results, which cover a relative hadron energy range from 0.1 to 0.9, significantly deviate from several theoretical calculations based on existing fragmentation functions.

Observation of a New X(3872) Production Process e^{+}e^{-}→ωX(3872)

Using 4.7  fb^{-1} of e^{+}e^{-} collision data at center-of-mass energies from 4.661 to 4.951 GeV collected by the BESIII detector at the BEPCII collider, we observe the X(3872) production process e^{+}e^{-}→ωX(3872) for the first time. The significance is 7.8σ, including both the statistical and systematic uncertainties. The e^{+}e^{-}→ωX(3872) Born cross section and the corresponding upper limit at 90% confidence level at each energy point are reported. The line shape of the cross section indicates that the ωX(3872) signals may be from the decays of some nontrivial structures.

Study of the Semileptonic Decay Λ_{c}^{+}→Λe^{+}ν_{e}

The study of the Cabibbo-favored semileptonic decay Λ_{c}^{+}→Λe^{+}ν_{e} is reported using a 4.5  fb^{-1} data sample of e^{+}e^{-} annihilations collected at center-of-mass energies ranging from 4.600 GeV to 4.699 GeV with the BESIII detector at the BEPCII collider. The branching fraction of the decay is measured to be B(Λ_{c}^{+}→Λe^{+}ν_{e})=(3.56±0.11_{stat}±0.07_{syst})%, which is the most precise measurement to date. Furthermore, we perform an investigation of the internal dynamics in Λ_{c}^{+}→Λe^{+}ν_{e}. We provide the first direct comparisons of the differential decay rate and form factors with those predicted from lattice quantum chromodynamics (LQCD) calculations. Combining the measured branching fraction with a q^{2}-integrated rate predicted by LQCD, we determine |V_{cs}|=0.936±0.017_{B}±0.024_{LQCD}±0.007_{τ_{Λ_{c}}}.

Measurement of the Absolute Branching Fraction and Decay Asymmetry of Λ→nγ

The radiative hyperon decay Λ→nγ is studied using (10087±44)×10^{6}  J/ψ events collected with the BESIII detector operating at BEPCII. The absolute branching fraction of the decay Λ→nγ is determined to be (0.832±0.038_{stat}±0.054_{syst})×10^{-3}, which is a factor of 2.1 lower and 5.6 standard deviations different than the previous measurement. By analyzing the joint angular distribution of the decay products, the first determination of the decay asymmetry α_{γ} is reported with a value of -0.16±0.10_{stat}±0.05_{syst}.

Precise Measurements of Decay Parameters and CP Asymmetry with Entangled Λ-Λ[over ¯] Pairs

Based on 10 billion J/ψ events collected at the BESIII experiment, a search for CP violation in Λ decay is performed in the difference between CP-odd decay parameters α_{-} for Λ→pπ^{-} and α_{+} for Λ[over ¯]→p[over ¯]π^{+} by using the process e^{+}e^{-}→J/ψ→ΛΛ[over ¯]. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters are determined to be α_{-}=0.7519±0.0036±0.0024 and α_{+}=-0.7559±0.0036±0.0030, respectively. The Λ and Λ[over ¯] averaged value of the decay parameter is extracted to be α_{avg}=0.7542±0.0010±0.0024 with unprecedented accuracy. The CP asymmetry A_{CP}=(α_{-}+α_{+})/(α_{-}-α_{+}) is determined to be -0.0025±0.0046±0.0012, which is one of the most precise measurements in the baryon sector. The reported results for the decay parameter will play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.

Comparative effectiveness of early rhythm control versus rate control for cardiovascular outcomes according to sex in patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health & Welfare, Republic of Korea

Background

Rhythm control is associated with better cardiovascular outcomes than usual care among patients recently diagnosed with atrial fibrillation (AF). However, there are limited data on the outcomes of AF ablation according to sex. The purpose of this study was to evaluate gender differences in the effects of early rhythm control compared to rate control on the primary composite outcome of cardiovascular death, ischaemic stroke, hospitalisation for heart failure (HF), or myocardial infarction.

Methods

We conducted a retrospective population-based cohort study including 22635 patients with AF newly treated with rhythm control (antiarrhythmic drugs or ablation) or rate control in 2011-2015 from the Korean National Health Insurance Service database. Propensity overlap weighting was used.

Results

Among patients with early AF treatment (initiated within 1 year since diagnosis), compared with rate control, rhythm control was associated with a similar lower risk of the primary composite outcome both women (weighted incidence rate per 100 person-years: 8.68 in rhythm control vs. 10.3 in rate control; hazard ratio [HR] 0.79, 95% confidence interval [CI] 0.69 to 0.90; P<0.001) and men (weighted incidence rate per 100 person-years: 6.33 in rhythm control vs. 8.32 in rate control; HR 0.77, 95% CI 0.67 to 0.88; P<0.001). However, the effective initiation time for rhythm control therapy was within 6 and 11 months after AF diagnosis in female and male patients, respectively. Moreover, the effective times for other outcomes were different between genders (hospitalization for HF; female within 2 months, male within 9 months/ ischemic stroke; female within 11 months, male immediately).

Conclusions

Early initiation of rhythm control was associated with a lower risk of primary outcome in both genders. However, the effective rhythm control treatment initiation time for primary outcome, stroke and HF-related admission was different in both genders. For rhythm control treatment to be effective, women should start treatment earlier than men.

First-year sea ice leads to an increase in dimethyl sulfide-induced particle formation in the Antarctic Peninsula

Dimethyl sulfide (DMS) produced by marine algae represents the largest natural emission of sulfur to the atmosphere. The oxidation of DMS is a key process affecting new particle formation that contributes to the radiative forcing of the Earth. In this study, atmospheric DMS and its major oxidation products (methanesulfonic acid, MSA; non-sea-salt sulfate, nss-SO₄^2-) and particle size distributions were measured at King Sejong station located in the Antarctic Peninsula during the austral spring-summer period in 2018-2020. The observatory was surrounded by open ocean and first-year and multi-year sea ice. Importantly, oceanic emissions and atmospheric oxidation of DMS showed distinct differences depending on source regions. A high mixing ratio of atmospheric DMS was observed when air masses were influenced by the open ocean and first-year sea ice due to the abundance of DMS producers such as pelagic phaeocystis and ice algae. However, the concentrations of MSA and nss-SO₄^2- were distinctively increased for air masses originating from first-year sea ice as compared to those originating from the open ocean and multi-year sea ice, suggesting additional influences from the source regions of atmospheric oxidants. Heterogeneous chemical processes that actively occur over first-year sea ice tend to accelerate the release of bromine monoxide (BrO), which is the most efficient DMS oxidant in Antarctica. Model-estimates for surface BrO confirmed that high BrO mixing ratios were closely associated with first-year sea ice, thus enhancing DMS oxidation. Consequently, the concentration of newly formed particles originated from first-year sea ice, which was a strong source area for both DMS and BrO was greater than from open ocean (high DMS but low BrO). These results indicate that first-year sea ice plays an important yet overlooked role in DMS-induced new particle formation in polar environments, where warming-induced sea ice changes are pronounced.

Catheter ablation can improve survival with the reduction of heart failure in frail patients with atrial fibrillation

Background

It is unclear whether catheter ablation is beneficial in frail patients with AF.

Purpose

This study aimed to evaluate whether catheter ablation reduces death and other outcomes in real-world frail patients with atrial fibrillation (AF).

Methods

Out of 801,710 patients with AF in the Korean National Health Insurance Service database from 2006 to 2015, 1,411 frail patients underwent AF ablations. The Hospital Frailty Risk Score were calculated retrospectively. Inverse probability of treatment weighting (IPTW) was used to categorize ablation and non-ablation frail groups.

Results

After IPTW, the two cohorts had similar background characteristics. During a median follow-up of 4.7 years (interquartile range: 2.2–7.8), the risk of death in frail patients with ablations was reduced by 65% compared to frail patients without ablations (2.0 and 6.4 per 100 person-years, respectively; hazard ratio [HR] 0.35; 95% confidence interval [CI] 0.25–0.50; P<0.001). Ablations were related with a lower incidence and risk of heart failure admission (1.8 and 3.1 per 100 person-years, respectively; HR 0.66, 95% CI 0.44–0.98; P=0.042) and acute myocardial infarction (0.2 and 0.6 per 100 person-years, respectively; HR 0.30, 95% CI 0.15–0.62; P=0.001). However, the risk of stroke did not change after ablation.

Conclussion

Ablation may be associated with lower incidences of death, heart failure, and acute myocardial infarction in real-world frail patients with AF, supporting the role of AF ablation in these patients. The effect of frailty risk on the outcome of ablation should be evaluated in further studies.

Funding Acknowledgement

Type of funding source: None

Elevation of pulse pressure in middle age is associated with the risk of dementia: data from a population-based cohort

Aims

Pulse pressure (PP) is a well-known risk factor for cardiovascular disease. However, the association between the PP and dementia is not well identified. This study aimed to determine the effect of PP on the risk of dementia development in different age subgroups using a longitudinal, population-based, and stroke-free cohort from the general population.

Methods

The association of PP with the development of incident dementia was assessed from January 1, 2005, to December 31, 2013, in 433,154 participants without a history of dementia or stroke from the Korea National Health Insurance Service-Health Screening cohort. The diagnosis of dementia was defined using the 10th revision of the International Classification of Disease codes.

Results

The mean age of the cohort was 55.7±9.2 years, 45.7% were women. Hypertension was 23.6%. The mean systolic and diastolic blood pressure of the entire cohort were 125.9±16.6 and 78.4±10.7 mmHg, respectively. Mean PP was 47.5±10.9 mmHg. In the middle-age group (40 to 50 year-old), increasing of 10 mmHg of PP was associated with incident dementia after adjusting mean blood pressure and clinical variables with a hazard ratio (HR) of 1.21 (95% confidence interval [CI]: 1.19–1.23, p<0.001). The association was still significant even after censoring for stroke (HR: 1.16, 95% CI: 1.08–1.22, p<0.001). In the older population, elevation of PP was not associated with dementia development (HR: 0.98, 95% CI: 0.95–1.01, p=0.247)

Conclusion

PP was associated with increased risk of dementia only in middle-aged population beyond that of mean arterial pressure.

Funding Acknowledgement

Type of funding source: None

0192 Sleep Characteristics and Mood of Professional Esports Athletes: A Multi-National Study

Introduction

Esports is becoming increasingly professionalized, yet research on performance management is remarkably lacking. The present study aimed to investigate sleep and mood in professional esports athletes.

Methods

Participants were 17 professional esports athletes from South Korea (8), Australia (4) and the US (5) who played First Person Shooter games (mean age 20±3.5 years, 100% male). All participants wore a wrist-activity monitor for 7–14 days, and completed subjective sleep and mood questionnaires.

Results

Based on data from the wrist-activity monitory, participants averaged 409±37 minutes of total sleep time, and 87±1% of sleep efficiency per night. All participants had significantly delayed sleep patterns (Average bed Time 3:41 am and wake Time 11:11 am). Participants had an average SOL of 26.15 minutes and prolonged wake after sleep onset of 51.91 (±31.84) minutes. Korean players had significantly higher depression scores compared to the other groups (p=.006) and trained longer than the Australian or US teams (13.38 vs. 4.75 vs. 6.10 hours, respectively). Depression scores were strongly correlated with number of awakenings, wake after sleep onset and training time per day (ps<.05).

Conclusion

As the first exploratory study in the esports field, the study indicates that esports athletes show delayed sleep patterns and have prolonged wake after sleep onset. These sleep patterns may be associated with mood (depression) and training time. There may also be cultural differences that contribute to sleep disturbance in this population.

Support

Korean Society of Sleep Medicine

P4758Label adherence of non-vitamin K antagonist oral anticoagulants and clinical outcomes in patients with atrial fibrillation: A nationwide study

Background

Dose adjustment of non-vitamin K antagonist oral anticoagulants (NOACs) is indicated in some patients with atrial fibrillation (AF), based on selected patient factors or concomitant medications.

Purpose

We assessed the frequency of label adherence of NOAC dosing among AF patients and the associations between off-label NOAC dosing and clinical outcomes in real-world clinical practice.

Methods

We evaluated 53,649 AF patients treated with a NOAC using Korean National Health Insurance Service database during the period from January 2013 to December 2016. NOAC doses were classified as either underdosed or overdosed, consistent with U.S. Food and Drug Administration labeling. Cox proportional hazards regression was performed to investigate the effectiveness and safety outcomes including stroke or systemic embolism, major bleeding, and all-cause mortality.

Results

Overall, 16,757 NOAC-treated patients (31.2%) were underdosed, 4,492 were overdosed (8.4%), and 32,400 (60.4%) were dosed appropriately according to drug labeling. Compared with patients with label adherence, those who were underdosed or overdosed were older (71±8 and 75±7 years of age vs. 70±9 years of age, respectively; p<0.001), more likely female (39% and 53% vs. 38%, respectively; p<0.001), and had higher CHA2DS2-VASc scores (4.6±1.7 and 5.3±1.7 vs. 4.5±1.8, respectively; p<0.001). NOAC overdosing was associated with increased risk for stroke or systemic embolism (5.76 vs. 4.03 events/100 patient-years, p<0.001), major bleeding (4.77 vs. 2.94 events/100 patient-years, p<0.001), and all-cause mortality (5.43 vs. 3.05 events/100 patient-years, p<0.001) compared with label-adherent use.

Figure 1

Conclusion

In routine clinical practice, a significant proportion (almost 2 in 5) of AF patients received NOAC doses inconsistent with drug labeling. NOAC overdosing is associated with increased risk for stroke or systemic embolism, major bleeding, and all-cause mortality in Asian patient with AF.

208Effect of hypertension duration and systolic blood pressure on dementia in patients with atrial fibrillation

Background

Atrial fibrillation (AF) is associated with a higher risk for cognitive impairment and dementia, with or without a history of clinical stroke. There are a paucity of data on the associations of hypertension duration and blood pressure (BP) level with risk of dementia in patients with AF.

Purpose

We examined associations of duration of hypertension and secondly, systolic blood pressure (SBP) levels with incidence of dementia among patients with AF.

Methods

We enrolled a total 196,388 patients aged ≥50 years who were newly diagnosed as AF and undergoing hypertension treatment from the Korean National Health Insurance Service database (2005–2016). Starting from AF diagnosis, participants were followed up until the date of dementia, death, or December 31, 2016. To incorporate the effect of BP level and hypertension duration changes over time on dementia incidence, we constructed time-updated multivariable Cox models in which BP levels and hypertension duration were updated at each participants' regular national health examination visits (at 0–7 years of follow-up). Similarly, age, BP medications, and health-related behaviors were included as time-varying covariates in these models.

Results

During 1,016,744 person-years of follow-up, there were 32,692 dementia events. A cubic spline curve using continuous hypertension duration measures suggested a linear association between increase of hypertension duration and dementia risk. One-year increase of hypertension duration increased the adjusted risk of dementia with a hazard ratio (HR) of 1.17 [95% confidence interval (CI) 1.13–1.22]. In patients with hypertension duration <6 years, SBP of ≥140 mmHg was significantly associated with higher dementia risk, compared to SBP of <130 mmHg (in patients with hypertension duration <3 years: adjusted HR 1.08, 95% CI 1.01–1.16; and in those with 3 ≤ hypertension duration <6 years: adjusted HR 1.13, 95% CI 1.07–1.20), whereas no significant association between SBP and dementia risk in those with hypertension duration ≥6 years.

SBP and dementia in different duration

Conclusion

In patients with AF, the increase of hypertension duration was strongly associated with increased risk of dementia. Uncontrolled SBP was also associated with higher dementia risk. But, this effect of SBP might be attenuated in patients with longer hypertension duration. These findings suggest more emphasis needed on BP control in AF patients with earlier phase of hypertension (duration <6 years).

Acknowledgement/Funding

The Korean Ministry of Education, Science and Technology (NRF-2017R1A2B3003303) and the Korean Ministry of Health & Welfare (HI16C0058, HI15C1200)

64Risk of dementia in patients treated with non-vitamin k antagonist oral anticoagulant or warfarin for nonvalvular atrial fibrillation

Background

Evidence is accumulating that use of oral anticoagulants (OACs) decreases the risk of dementia in patients with atrial fibrillation (AF), but it is unclear if there is a difference between non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin in protecting against dementia.

Purpose

To compare the risk of dementia between patients taking either NOAC or warfarin using a nationwide cohort data covering the entire Korean population.

Methods

Using the Korean national health insurance service database, 68,984 new OAC users with non-valvular AF aged ≥50 years and no prior diagnosis of dementia were identified during the period of 2013–2016 (39,687 NOAC users and 29,297 warfarin users). Starting from OAC initiation, participants were followed up until the date of dementia, death, or December 31, 2016. We compared the rates of dementia in 1:1 propensity score-matched cohorts of NOAC (n=18,925) and warfarin users (n=18,925).

Results

During the 52,259 person-years of follow-up, there were 2,750 dementia events. Use of NOAC was associated with significant lower risk of dementia [hazard ratio (HR) 0.75, 95% confidence interval (CI) 0.69–0.81], compared with warfarin. The risk reduction was prominent for vascular dementia (HR 0.60, 95% CI 0.52–0.71), whereas there was no significant difference in the risk of Alzheimer dementia (HR 0.92, 95% CI 0.83–1.02). Restricting the analyses to patients with no stroke diagnosis prior to OAC initiation (primary prevention) showed no significant difference between NOAC and warfarin in any types of dementia, but in the subgroup with prior stroke (secondary prevention), NOAC significantly reduced the risk of overall (HR 0.70, 95% CI 0.63–0.78) and vascular dementia (HR 0.59, 95% CI 0.49–0.69).

Subgroup analysis according to stroke Hx Patient N Overall dementia Alzheimer dementia Vascular dementia HR (95% CI) P for interaction HR (95% CI) P for interaction HR (95% CI) P for interaction Total 37,850 0.75 (0.69–0.81) 0.92 (0.83–1.02) 0.60 (0.52–0.71) Without prior stroke 24,773 0.90 (0.78–1.05) 0.948 0.98 (0.83–1.15) 0.235 0.85 (0.56–1.28) 0.863 With prior stroke 13,077 0.70 (0.63–0.78) 0.90 (0.79–1.03) 0.59 (0.49–0.69) CI, confidence interval; HR, hazard ratio.

KM curves of dementia incidence

Conclusion

In this propensity-weighted nationwide cohort of non-valvular AF patients, NOAC was associated with reduced risk of dementia, compared with warfarin. This association was the most pronounced for vascular dementia in patients with prior stroke.

Acknowledgement/Funding

The Korean Ministry of Education, Science and Technology (NRF-2017R1A2B3003303) and the Korean Ministry of Health & Welfare (HI16C0058, HI15C1200)

P1027The risk of dementia and catheter ablation for atrial fibrillation: a nationwide cohort study

Background

Atrial fibrillation (AF) is associated with all forms of dementia, including Alzheimer's disease. Catheter ablation of AF reduces the number of AF episodes, prolongs the time in sinus rhythm, and improves quality of life. However, it is still unclear if catheter ablation for AF improve cognitive function and prevent dementia. Our objective was to compare long-term outcome regarding dementia and type of dementia in AF patients with and without ablation, and about long-term exposure to anticoagulants.

Methods

We identified all 801,701 patients with a diagnosis of AF from 2006 to 2015 in the Korean national health insurance service database. During ten years, 10,979 AF ablations were performed among 9,768 individuals. Propensity scores for the likelihood of AF ablation were obtained by logistic regression. Propensity score (PS) matching was used to construct two cohorts of equal size (n=9,768) with similar characteristics in 16 dimensions.

Results

Patients who had undergone catheter ablation were younger (57.2 vs. 65.6 years, P<0.001) and healthier (mean CHA2DS2-VASc scores 2.5±1.7 vs. 3.6±2.1, p<0.001) than other patients with AF. Mean follow-up was 5.5±3.1 years. After propensity score matching, in the ablated group, 184 patients suffered dementia compared with 650 in the matched non-ablated (annual rates 0.42 vs. 1.08%, P<0.001). While a total of 134 ablated and 379 non-ablated patients had Alzheimer disease (annual rates 0.31 vs. 0.62%, p<0.001), 40 ablated and 191 non-ablated patients had vascular disease (annual rates 0.09 vs. 0.31%, p<0.001). After multivariable adjustments, catheter ablation was associated with lower risk of dementia (hazard ratio [HR] 0.46, 95% confidence interval [CI] 0.37–0.58), lower risk of Alzheimer disease (HR 0.61, 95% CI 0.46–0.79) and lower risk of vascular dementia (HR 0.27, 95% CI 0.19–0.38). Although the reduction of dementia and Alzheimer disease was observed after AF ablation regardless of thromboembolic risk, vascular dementia was reduced only among patients with CHA2DS2-VASc score ≥2 (HR 0.29, 95% CI 0.20–0.42).

The risk of dementia, RFCA vs. no-RFCA Type Propensity score matched ablation group vs. no ablation group adjusted HR (95% CI) P-value Overall dementia 0.46 (0.37–0.58) <0.001 Alzheimer dementia 0.61 (0.46–0.79) <0.001 Vascular dementia 0.27 (0.19–0.38) <0.001

Conclusion

Ablation may be associated with a lower incidence of dementia and both type of dementia in patients with AF. This finding appears more pronounced in patients with high thromboembolic risk factors.

Impact of psychological characteristics in self-management in individuals with traumatic spinal cord injury

Study design:

Cross-sectional survey.

Objective:

To examine the association between psychological characteristics in self-management and probable depression status in individuals with a traumatic spinal cord injury (SCI).

Setting:

Community-dwelling individuals with traumatic SCI living across Canada.

Methods:

Individuals with SCI were recruited by email via the Rick Hansen Institute as well as an outpatient hospital spinal clinic. Data were collected by self-report using an online survey. Standardized questionnaires were embedded within a larger survey and included the Hospital Anxiety and Depression Scale (HADS), the short version of the Patient Activation Measure (PAM), the Moorong Self-Efficacy Scale (MSES) and the Pearlin-Schooler Mastery Scale (PMS).

Results:

Individuals with probable depression (n=25) had lower self-efficacy (67.9 vs 94.2, P<0.0001), mastery (18.9 vs 22.9, P<0.0001) and patient activation (60.4 vs 71.6, P<0.0001) as well as higher anxiety (9.0 vs 5.5, P<0.0001), compared with their non-depressed counterparts (n=75). A logistic regression determined that lower self-efficacy and mastery scores as well as less time since injury were associated with depression status (P=0.002; P=0.02 and P=0.02, respectively). Individuals with higher anxiety scores were almost 1.5 times more likely to be depressed, while older age was positively associated with depression status (P=0.016 and P=0.024, respectively).

Conclusion:

Interventions for depression in SCI, including a self-management program, should target factors such as self-efficacy and mastery, which could improve secondary medical complications and overall quality of life.

Neural prosthesis in the wake of nanotechnology: controlled growth of neurons using surface nanostructures

Neural prosthesis has been successfully applied to patients with motional or sensory disabilities for clinical purpose. To enhance the performance of the neural prosthetic device, the electrodes for the biosignal recording or electrical stimulation should be located in closer proximity to target neurons than they are now. Instead of revising the prior implanting surgery to improve the electrical contact of neurons, we propose a technique that can bring the neurons closer to the electrode sites. A new method is investigated that can control the direction of neural cell growth using surface nanostructures. We successfully guide the neurons to the position of the microelectrodes by providing a surface topographical cue presented by the surface nanostructure on a photoresponsive polymer material. Because the surface structure formed by laser holography is reversible and repeatable, the geometrical positioning of the neurons to microelectrodes can be adjusted by applying laser treatment during the surgery for the purpose of improving the performance of neural prosthetic device.

Nitric oxide synthase in the autonomic nervous system of canine ileum

The synaptosomes from canine ileal deep muscular plexus possess a nitric oxide (NO)-sensitive soluble guanylate cyclase, as demonstrated by approximately 3- to 4-fold elevation of synaptosomal cyclic GMP levels in the presence of either 1 mM sodium nitroprusside or L-arginine (20-1,000 microM) plus 1 mM NADPH. The activating effect of L-arginine on synaptosomal soluble guanylate cyclase was related to its enzymatic conversion to citrulline by NO synthase. The synaptosomal NO synthase was found to exhibit both calcium-independent and calcium/calmodulin-dependent components accounting for approximately 2- to 2.5-fold and 7- to 8-fold increases in the basal activity, respectively. The absolute magnitude of these activities was several-fold greater compared to the activities observed in the isolated cells of circular smooth muscle. The synaptosomal Ca-independent and Ca/calmodulin-dependent NO synthase activities were inhibited by methylene blue and L-NG-arginine methyl ester. The NO synthase activity was also attenuated in the presence of cyclic AMP (10 microM). Such an inhibition was related primarily to the suppression of Ca-independent activity. The ability of enteric nerves to generate NO from L-arginine strongly suggests the involvement of this process in the biochemical mechanisms underlying the neurogenic control of intestinal motility.

Alpha 2-adrenergic receptors on the circular smooth muscle of canine small intestine

We have studied the distribution and properties of alpha 2-adrenergic receptors in the circular muscle layer (containing deep muscular plexus) of canine small intestine. Using radioactivity labelled rauwolscine, we located the binding sites to the neuronal membranes supporting the prejunctional action of alpha 2-adrenergic agents in the gut. Moreover, although the functional data to suggest the existence of postjunctional alpha 2-adrenergic receptors coupled to contraction are not available so far, we measured a substantial number of rauwolscine binding sites on the smooth muscle plasma membranes. Scatchard and Hill analyses of the saturation data were indicative of the presence of a single high affinity site (Hill coefficient 0.996) with a KD value of 8.8 nM and the maximum number of binding sites (Bmax) of 313 fmol/mg of protein. Competition studies suggested the presence of multiple subtypes of alpha 2-adrenoceptors.

Calcium channel binding in nerves and muscle of canine small intestine

Using [3H]-nitrendipine (Nit) and [125I]-omega conotoxin (w-CTX), the cellular and subcellular distribution of calcium channel subtypes in the homogenates of canine small intestinal circular muscle was studied. Nit. bound to the membranes from the circular smooth muscle cells (PM) and to the synaptosomal membranes from the deep muscular plexus (DMP); the Kd and Bmax values of Nit binding from these two sources were similar (Kd 0.4 +/- 0.16 nM and 0.77 +/- 0.24 nM; Bmax 206 +/- 22 and 192 +/- 39 fmol/mg of protein in DMP and PM respectively). w-CTX, however, bound only to the DMP (Kd 18.41 +/- 7.5 pM, Bmax 265 +/- 36 fmol/mg of protein). In DMP, nifedipine (10(-6) M) failed to interact with the binding of w-CTX; similarly, no modulation of Nit binding with unlabelled w-CTX (10(-7) M) could be detected. Therefore w-CTX and Nit binding sites represent two distinct, non-interactive and differentially distributed binding sites in canine small intestine.