Single-Molecule Characterization of Heterogeneous Oligomer Formation during Co-Aggregation of 40- and 42-Residue Amyloid-ß.

The two most abundant isoforms of amyloid-ß (Aß) are the 40- (Aß40) and 42-residue (Aß42) peptides. Since they coexist and there is a correlation between toxicity and the ratio of the two isoforms, quantitative characterization of their interactions is crucial for understanding the Aß aggregation mechanism. In this work, we follow the aggregation of individual isoforms in a mixture using single-molecule FRET spectroscopy by labeling Aß42 and Aß40 with the donor and acceptor fluorophores, respectively. We found that there are two phases of aggregation. The first phase consists of coaggregation of Aß42 with a small amount of Aß40, while the second phase results mostly from aggregation of Aß40. We also found that the aggregation of Aß42 is slowed by Aß40 while the aggregation of Aß40 is accelerated by Aß42 in a concentration-dependent manner. The formation of oligomers was monitored by incubating mixtures in a plate reader and performing a single-molecule free-diffusion experiment at several different stages of aggregation. The detailed properties of the oligomers were obtained by maximum likelihood analysis of fluorescence bursts. The FRET efficiency distribution is much broader than that of the Aß42 oligomers, indicating the diversity in isoform composition of the oligomers. Pulsed interleaved excitation experiments estimate that the fraction of Aß40 in the co-oligomers in a 1:1 mixture of Aß42 and Aß40 varies between 0 and 20%. The detected oligomers were mostly co-oligomers especially at the physiological ratio of Aß42 and Aß40 (1:10), suggesting the critical role of Aß40 in oligomer formation and aggregation.

Analysis of photon trajectories from diffusing single molecules.

In single-molecule free diffusion experiments, molecules spend most of the time outside a laser spot and generate bursts of photons when they diffuse through the focal spot. Only these bursts contain meaningful information and, therefore, are selected using physically reasonable criteria. The analysis of the bursts must take into account the precise way they were chosen. We present new methods that allow one to accurately determine the brightness and diffusivity of individual molecule species from the photon arrival times of selected bursts. We derive analytical expressions for the distribution of inter-photon times (with and without burst selection), the distribution of the number of photons in a burst, and the distribution of photons in a burst with recorded arrival times. The theory accurately treats the bias introduced due to the burst selection criteria. We use a Maximum Likelihood (ML) method to find the molecule's photon count rate and diffusion coefficient from three kinds of data, i.e., the bursts of photons with recorded arrival times (burstML), inter-photon times in bursts (iptML), and the numbers of photon counts in a burst (pcML). The performance of these new methods is tested on simulated photon trajectories and on an experimental system, the fluorophore Atto 488.

Precision and accuracy of single-molecule FRET measurements-a multi-laboratory benchmark study.

Single-molecule Förster resonance energy transfer (smFRET) is increasingly being used to determine distances, structures, and dynamics of biomolecules in vitro and in vivo. However, generalized protocols and FRET standards to ensure the reproducibility and accuracy of measurements of FRET efficiencies are currently lacking. Here we report the results of a comparative blind study in which 20 labs determined the FRET efficiencies (E) of several dye-labeled DNA duplexes. Using a unified, straightforward method, we obtained FRET efficiencies with s.d. between ±0.02 and ±0.05. We suggest experimental and computational procedures for converting FRET efficiencies into accurate distances, and discuss potential uncertainties in the experiment and the modeling. Our quantitative assessment of the reproducibility of intensity-based smFRET measurements and a unified correction procedure represents an important step toward the validation of distance networks, with the ultimate aim of achieving reliable structural models of biomolecular systems by smFRET-based hybrid methods.

Publisher Correction: Precision and accuracy of single-molecule FRET measurements-a multi-laboratory benchmark study.

This paper was originally published under standard Springer Nature copyright. As of the date of this correction, the Analysis is available online as an open-access paper with a CC-BY license. No other part of the paper has been changed.

E-cigarette-associated Severe Pneumonia in Korea Using Data Linkage between the Korea National Health and Nutrition Examination Survey (KNHANES, 2013-2019) and the National Health Insurance Service (NHIS) Claims Database.

BACKGROUND: This study aimed to investigate the association between e-cigarette (EC) use and development of acute severe pneumonia in the Korean population using a national database. METHODS: We conducted a retrospective analysis using linkage of data between the Korean National Health and Nutrition Examination Survey (KNHANES) and the National Health Insurance Service (NHIS) administrative claims database. The primary endpoint of this study was development of severe pneumonia requiring hospital admission according to EC use during the study period. The secondary endpoints were in-hospital mortality, intensive care unit (ICU) admission, ventilator care, and days of hospital stay. RESULTS: The final analysis included 28,950 individuals, of which 578 (2.0%) were EC users. EC users were younger and more often male than non-EC users. The EC users showed higher level of education and household income and had fewer comorbidities. Severe pneumonia was noted in 37 of 28,372 non-EC users (0.13%), but there were no occurrences of severe pneumonia in EC users. The incidence of pneumonia occurrence was not different between the two groups (P = 1.000). CONCLUSIONS: Since e-cigarette or vaping use-associated lung injury (EVALI) is most likely included in acute severe pneumonia occurring within 3 months of EC use, it is considered that there might be no EVALI patients in Korea during the investigation period. A large-scale, prospective study is necessary to evaluate the association between EC use and acute lung injury.

Oligomerization of the tetramerization domain of p53 probed by two- and three-color single-molecule FRET.

We describe a method that combines two- and three-color single-molecule FRET spectroscopy with 2D FRET efficiency-lifetime analysis to probe the oligomerization process of intrinsically disordered proteins. This method is applied to the oligomerization of the tetramerization domain (TD) of the tumor suppressor protein p53. TD exists as a monomer at subnanomolar concentrations and forms a dimer and a tetramer at higher concentrations. Because the dissociation constants of the dimer and tetramer are very close, as we determine in this paper, it is not possible to characterize different oligomeric species by ensemble methods, especially the dimer that cannot be readily separated. However, by using single-molecule FRET spectroscopy that includes measurements of fluorescence lifetime and two- and three-color FRET efficiencies with corrections for submillisecond acceptor blinking, we show that it is possible to obtain structural information for individual oligomers at equilibrium and to determine the dimerization kinetics. From these analyses, we show that the monomer is intrinsically disordered and that the dimer conformation is very similar to that of the tetramer but the C terminus of the dimer is more flexible.

Enhanced Solubility, In-Vitro Dissolution and Lipase Inhibition of a Self-Nanoemulsifying Drug Delivery System Containing Orlistat.

The aim of this work was to prepare and assess a self-nanoemulsifying drug delivery system (SNEDDS) containing water-insoluble orlistat that was used for the inhibition of lipase activity in gastrointestinal lumen. The pseudo-ternary phase diagram, composed of orlistat and medium chain triglycerides (MCT) as oil phase and Cremophor EL as surfactant, was made for the confirmation of giving SNEDDS preconcentrate. The physical state, particle size dispersed in water, dissolution and lipase inhibition of SNEDDS preconcentrates were investigated. The appointed SNEDDS preconcentrates in the pseudo-ternary phase diagram showed no endothermic peak of orlistat and a liquid state. The particle sizes of SNEDDS dispersed with water were uniform and in the range of <200 nm. In the dissolution test, the liquid SNEDDS preconcentrate and solid state mixture exhibited 90.89±2.03% versus 22.42±3.71% at 60 min., respectively, whereas the raw orlistat showed no significant dissolution rate. The SNEDDS preconcentrate showed a lipase inhibition of 92.42±1.58% until 60 min., with no significant inhibition activity of orlistat. Therefore, the SNEDDS preconcentrate presented in this work solubilized orlistat and increased its dissolution rate, and resulted in sufficient inhibitory action on lipase.

Preparation, Characterization, and In Vitro Release of Chitosan-Ecabet Electrolyte Complex for the Mucosal Delivery.

Ecabet has a mucosal protection and anti-Helicobacter pylori effect only by local action in the gastric mucous layer, due to an extremely poor absorption into the systemic blood circulation. The aim of the present work was to develop chitosan-ecabet electrolyte complex (ChE) for the enhanced mucosal drug delivery. ChEs were prepared with various ecabet-chitosan concentration ratios. Entrapment efficiency (%), sedimentation volume (%), transmission electron microscopy (TEM), FT-IR spectrum, and drug release were investigated. ChEs were prepared by the simple mixing method in a pH-adjusted solution based on the electrostatic interaction between the sulfonate (negatively charged) group from ecabet and the amine (positively charged) group from chitosan. Sedimentation volume and entrapment efficiency at the same concentration of ecabet sodium with that of chitosan resulted in 53.6% and 86.75%, respectively, suggesting a high degree of forming complex. In TEM images, the complex was approximately 200 nm in particle size and had loosely entangled particles. Forming complex of ChEs was supported by new bands appearance in the FT-IR spectrum. In the drug release study using dialysis membrane sac, ChEs showed a sustainable release up to 80% during 12 h as compared to ecabet sodium suspension at pH 1.2 medium. Based on the results of this work, ChE would be a promising drug delivery system for gastric mucosa.

Procalcitonin-Guided Treatment on Duration of Antibiotic Therapy and Cost in Septic Patients (PRODA): a Multi-Center Randomized Controlled Trial.

BACKGROUND: The objective of this study was to establish the efficacy and safety of procalcitonin (PCT)-guided antibiotic discontinuation in critically ill patients with sepsis in a country with a high prevalence of antimicrobial resistance and a national health insurance system. METHODS: In a multi-center randomized controlled trial, patients were randomly assigned to a PCT group (stopping antibiotics based on a predefined cut-off range of PCT) or a control group. The primary end-point was antibiotic duration. We also performed a cost-minimization analysis of PCT-guided antibiotic discontinuation. RESULTS: The two groups (23 in the PCT group and 29 in the control group) had similar demographic and clinical characteristics except for need for renal replacement therapy on ICU admission (46% vs. 14%; P = 0.010). In the per-protocol analysis, the median duration of antibiotic treatment for sepsis was 4 days shorter in the PCT group than the control group (8 days; interquartile range [IQR], 6-10 days vs. 14 days; IQR, 12-21 days; P = 0.001). However, main secondary outcomes, such as clinical cure, 28-day mortality, hospital mortality, and ICU and hospital stays were not different between the two groups. In cost evaluation, PCT-guided therapy decreased antibiotic costs by USD 30 (USD 241 in the PCT group vs. USD 270 in the control group). The results of the intention-to-treat analysis were similar to those obtained for the per-protocol analysis. CONCLUSION: PCT-guided antibiotic discontinuation in critically ill patients with sepsis could reduce the duration of antibiotic use and its costs with no apparent adverse outcomes. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02202941.

Highly Disordered Amyloid-ß Monomer Probed by Single-Molecule FRET and MD Simulation.

Monomers of amyloid-ß (Aß) protein are known to be disordered, but there is considerable controversy over the existence of residual or transient conformations that can potentially promote oligomerization and fibril formation. We employed single-molecule Förster resonance energy transfer (FRET) spectroscopy with site-specific dye labeling using an unnatural amino acid and molecular dynamics simulations to investigate conformations and dynamics of Aß isoforms with 40 (Aß40) and 42 residues (Aß42). The FRET efficiency distributions of both proteins measured in phosphate-buffered saline at room temperature show a single peak with very similar FRET efficiencies, indicating there is apparently only one state. 2D FRET efficiency-donor lifetime analysis reveals, however, that there is a broad distribution of rapidly interconverting conformations. Using nanosecond fluorescence correlation spectroscopy, we measured the timescale of the fluctuations between these conformations to be ∼35 ns, similar to that of disordered proteins. These results suggest that both Aß40 and Aß42 populate an ensemble of rapidly reconfiguring unfolded states, with no long-lived conformational state distinguishable from that of the disordered ensemble. To gain molecular-level insights into these observations, we performed molecular dynamics simulations with a force field optimized to describe disordered proteins. We find, as in experiments, that both peptides populate configurations consistent with random polymer chains, with the vast majority of conformations lacking significant secondary structure, giving rise to very similar ensemble-averaged FRET efficiencies.

Light-Induced Fluorescence Modulation of Quantum Dot-Crystal Violet Conjugates: Stochastic Off-On-Off Cycles for Multicolor Patterning and Super-Resolution.

Photoswitching or modulation of quantum dots (QDs) can be promising for many fields that include display, memory, and super-resolution imaging. However, such modulations have mostly relied on photomodulations of conjugated molecules in QD vicinity, which typically require high power of high energy photons at UV. We report a visible light-induced facile modulation route for QD-dye conjugates. QD crystal violets conjugates (QD-CVs) were prepared and the crystal violet (CV) molecules on QD quenched the fluorescence efficiently. The fluorescence of QD-CVs showed a single cycle of emission burst as they go through three stages of (i) initially quenched "off" to (ii) photoactivated "on" as the result of chemical change of CVs induced by photoelectrons from QD and (iii) back to photodarkened "off" by radical-associated reactions. Multicolor on-demand photopatterning was demonstrated using QD-CV solid films. QD-CVs were introduced into cells, and excitation with visible light yielded photomodulation from "off" to "on" and "off" by nearly ten fold. Individual photoluminescence dynamics of QD-CVs was investigated using fluorescence correlation spectroscopy and single QD emission analysis, which revealed temporally stochastic photoactivations and photodarkenings. Exploiting the stochastic fluorescence burst of QD-CVs, simultaneous multicolor super-resolution localizations were demonstrated.

Solution single-vesicle assay reveals PIP2-mediated sequential actions of synaptotagmin-1 on SNAREs.

Synaptotagmin-1 (Syt1) is a major Ca(2+) sensor for synchronous neurotransmitter release, which requires vesicle fusion mediated by SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors). Syt1 utilizes its diverse interactions with target membrane (t-) SNARE, SNAREpin, and phospholipids, to regulate vesicle fusion. To dissect the functions of Syt1, we apply a single-molecule technique, alternating-laser excitation (ALEX), which is capable of sorting out subpopulations of fusion intermediates and measuring their kinetics in solution. The results show that Syt1 undergoes at least three distinct steps prior to lipid mixing. First, without Ca(2+), Syt1 mediates vesicle docking by directly binding to t-SNARE/phosphatidylinositol 4,5-biphosphate (PIP(2)) complex and increases the docking rate by 10(3) times. Second, synaptobrevin-2 binding to t-SNARE displaces Syt1 from SNAREpin. Third, with Ca(2+), Syt1 rebinds to SNAREpin, which again requires PIP(2). Thus without Ca(2+), Syt1 may bring vesicles to the plasma membrane in proximity via binding to t-SNARE/PIP(2) to help SNAREpin formation and then, upon Ca(2+) influx, it may rebind to SNAREpin, which may trigger synchronous fusion. The results show that ALEX is a powerful method to dissect multiple kinetic steps in the vesicle fusion pathway.

Large α-synuclein oligomers inhibit neuronal SNARE-mediated vesicle docking.

Parkinson disease and dementia with Lewy bodies are featured with the formation of Lewy bodies composed mostly of α-synuclein (α-Syn) in the brain. Although evidence indicates that the large oligomeric or protofibril forms of α-Syn are neurotoxic agents, the detailed mechanisms of the toxic functions of the oligomers remain unclear. Here, we show that large α-Syn oligomers efficiently inhibit neuronal SNARE-mediated vesicle lipid mixing. Large α-Syn oligomers preferentially bind to the N-terminal domain of a vesicular SNARE protein, synaptobrevin-2, which blocks SNARE-mediated lipid mixing by preventing SNARE complex formation. In sharp contrast, the α-Syn monomer has a negligible effect on lipid mixing even with a 30-fold excess compared with the case of large α-Syn oligomers. Thus, the results suggest that large α-Syn oligomers function as inhibitors of dopamine release, which thus provides a clue, at the molecular level, to their neurotoxicity.

The Association of Fever with Total Mechanical Ventilation Time in Critically Ill Patients.

This research aims to investigate the impact of fever on total mechanical ventilation time (TVT) in critically ill patients. Subgroup analysis was conducted using a previous prospective, multicenter observational study. We included mechanically ventilated patients for more than 24 hours from 10 Korean and 15 Japanese intensive care units (ICU), and recorded maximal body temperature under the support of mechanical ventilation (MAX(MV)). To assess the independent association of MAX(MV) with TVT, we used propensity-matched analysis in a total of 769 survived patients with medical or surgical admission, separately. Together with multiple linear regression analysis to evaluate the association between the severity of fever and TVT, the effect of MAX(MV) on ventilator-free days was also observed by quantile regression analysis in all subjects including non-survivors. After propensity score matching, a MAX(MV) ≥ 37.5°C was significantly associated with longer mean TVT by 5.4 days in medical admission, and by 1.2 days in surgical admission, compared to those with MAX(MV) of 36.5°C to 37.4°C. In multivariate linear regression analysis, patients with three categories of fever (MAX(MV) of 37.5°C to 38.4°C, 38.5°C to 39.4°C, and ≥ 39.5°C) sustained a significantly longer duration of TVT than those with normal range of MAX(MV) in both categories of ICU admission. A significant association between MAX(MV) and mechanical ventilator-free days was also observed in all enrolled subjects. Fever may be a detrimental factor to prolong TVT in mechanically ventilated patients. These findings suggest that fever in mechanically ventilated patients might be associated with worse mechanical ventilation outcome.

ß-Amyloid and α-synuclein cooperate to block SNARE-dependent vesicle fusion.

Alzheimer's disease (AD) and Parkinson's disease (PD) are caused by ß-amyloid (Aß) and α-synuclein (αS), respectively. Ample evidence suggests that these two pathogenic proteins are closely linked and have a synergistic effect on eliciting neurodegenerative disorders. However, the pathophysiological consequences of Aß and αS coexistence are still elusive. Here, we show that large-sized αS oligomers, which are normally difficult to form, are readily generated by Aß42-seeding and that these oligomers efficiently hamper neuronal SNARE-mediated vesicle fusion. The direct binding of the Aß-seeded αS oligomers to the N-terminal domain of synaptobrevin-2, a vesicular SNARE protein, is responsible for the inhibition of fusion. In contrast, large-sized Aß42 oligomers (or aggregates) or the products of αS incubated without Aß42 have no effect on vesicle fusion. These results are confirmed by examining PC12 cell exocytosis. Our results suggest that Aß and αS cooperate to escalate the production of toxic oligomers, whose main toxicity is the inhibition of vesicle fusion and consequently prompts synaptic dysfunction.

High Affinity Host-Guest FRET Pair for Single-Vesicle Content-Mixing Assay: Observation of Flickering Fusion Events.

Fluorescence-based single-vesicle fusion assays provide a powerful method for studying mechanisms underlying complex biological processes of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)-mediated vesicle fusion and neurotransmitter release. A crucial element of these assays is the ability of the fluorescent probe(s) to reliably detect key intermediate events of fusion pore opening and content release/mixing. Here, we report a new, reliable, and efficient single-vesicle content-mixing assay using a high affinity, fluorophore tagged host-guest pair, cucurbit[7]uril-Cy3 and adamantane-Cy5 as a fluorescence resonance energy transfer (FRET) pair. The power of these probes is demonstrated by the first successful observation of flickering dynamics of the fusion pore by in vitro assay using neuronal SNARE-reconstituted vesicles.

Efficacy and safety of aclidinium bromide in patients with COPD: A phase 3 randomized clinical trial in a Korean population.

BACKGROUND AND OBJECTIVE: Aclidinium bromide ('aclidinium') is a novel, inhaled long-acting muscarinic antagonist. Therapeutic effects of aclidinium on chronic obstructive pulmonary disease (COPD) have been demonstrated in Caucasian populations in several clinical trials. This was a randomized, double-blind, multi-centre phase-3 clinical trial to evaluate the efficacy and safety of aclidinium in a Korean population. METHODS: A total of 263 Korean patients with moderate-to-severe COPD were randomized to receive aclidinium (400 µg, bd) (Genuai) or placebo via a dry-powder inhaler. The primary end point was change in trough forced expiratory volume in one second (FEV1 ) at 12 weeks. Other lung function measurements, COPD exacerbation, health status (St George's Respiratory Questionnaire (SGRQ), dyspnoea (Transition Dyspnea Index (TDI) and safety were assessed throughout the study period. RESULTS: A significant improvement in trough FEV1 from baseline was shown with aclidinium compared with the placebo (0.126 L, P < 0.0001). Significant improvements were also demonstrated in peak FEV1 (0.190 L, P < 0.0001), SGRQ and TDI. Furthermore, aclidinium significantly reduced the prevalence of exacerbations (aclidinium, 5.4%; placebo, 15.6%, P < 0.05), and the duration of exacerbations was shorter compared with placebo (rate ratio: 0.27; P < 0.05). Aclidinium (400 µg) was well tolerated and the prevalence of adverse events was comparable with the placebo. CONCLUSIONS: Inhaled aclidinium (400 µg) was shown to be safe and efficacious in Korean patients with moderate-to-severe COPD. CLINICAL TRIAL REGISTRATION: NCT01636401 at Clinicaltrials.gov.

Dynamic Release of Bending Stress in Short dsDNA by Formation of a Kink and Forks.

Bending with high curvature is one of the major mechanical properties of double-stranded DNA (dsDNA) that is essential for its biological functions. The emergence of a kink arising from local melting in the middle of dsDNA has been suggested as a mechanism of releasing the energy cost of bending. Herein, we report that strong bending induces two types of short dsDNA deformations, induced by two types of local melting, namely, a kink in the middle and forks at the ends, which we demonstrate using D-shaped DNA nanostructures. The two types of deformed dsDNA structures dynamically interconvert on a millisecond timescale. The transition from a fork to a kink is dominated by entropic contribution (anti-Arrhenius behavior), while the transition from a kink to a fork is dominated by enthalpic contributions. The presence of mismatches in dsDNA accelerates kink formation, and the transition from a kink to a fork is removed when the mismatch size is three base pairs.

Usefulness of N-terminal pro-B-type natriuretic peptide in patients admitted to the intensive care unit: a multicenter prospective observational study.

BACKGROUND: The role of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) as a prognostic factor in patients admitted to the intensive care unit (ICU) is not yet fully established. We aimed to determine whether NT-pro-BNP is predictive of ICU mortality in a multicenter cohort of critically ill patients. METHODS: A total of 1440 patients admitted to 22 ICUs (medical, 14; surgical, six; multidisciplinary, two) in 15 tertiary or university-affiliated hospitals between July 2010 and January 2011 were assessed. Patient data, including NT-pro-BNP levels and Simplified Acute Physiology Score (SAPS) 3 scores, were recorded prospectively in a web-based database. RESULTS: The median age was 64 years (range, 53-73 years), and 906 (62.9%) patients were male. The median NT-pro-BNP level was 341 pg/mL (104-1,637 pg/mL), and the median SAPS 3 score was 57 (range, 47-69). The ICU mortality rate was 18.9%, and hospital mortality was 24.5%. Hospital survivors showed significantly lower NT-pro-BNP values than nonsurvivors (245 pg/mL [range, 82-1,053 pg/mL] vs. 875 pg/mL [241-5,000 pg/mL], respectively; p < 0.001). In prediction of hospital mortality, the area under the curve (AUC) for NT-pro-BNP was 0.67 (95% confidence interval [CI], 0.64-0.70) and SAPS 3 score was 0.83 (95% CI, 0.81-0.85). AUC increment by adding NT-pro-BNP is minimal and likely no different to SAPS 3 alone. CONCLUSIONS: The NT-pro-BNP level was more elevated in nonsurvivors in a multicenter cohort of critically ill patients. However, there was little additional prognostic power when adding NT-pro-BNP to SAPS 3 score.

Sex differences in chronic obstructive pulmonary disease characteristics: the Korea National Health and Nutrition Examination Survey 2007-2018.

BACKGROUND/AIMS: Chronic obstructive pulmonary disease (COPD) is less prevalent in females than males, but it affects mortality in females. There may be sex differences in the clinical characteristics of COPD. METHODS: We analyzed the Korea National Health and Nutrition Examination Survey dataset from 2007 to 2018. We compared the clinical characteristics and comorbidities in subjects with COPD according to sex. We adjusted the multivariate logistic regression of lung cancer prevalence according to COPD and sex by age and smoking amount. RESULTS: Females with COPD tended to be older than males with COPD (64.1 ± 0.4 yr vs. 62.3 ± 0.2 yr, respectively, p < 0.001). Approximately 89% of males with COPD had a smoking history, while 86% of females with COPD were non-smokers (p < 0.001). Household income was lower (p < 0.001) and asthma and overall malignancy were more prevalent in females with COPD than males with COPD (25.5 vs. 11.6%, respectively, p < 0.001; (6.3 vs. 5.4%, respectively, p < 0.001). However, lung cancer was more common in males with COPD than females with COPD (0.9 vs. 0.1%, respectively, p < 0.001). Lung cancer prevalence increased in males with moderate COPD compared to subjects without COPD (OR, 4.409; 95% CI, 1.741-9.419). CONCLUSION: Females with COPD had a lower smoking rate, household income, and lung cancer prevalence than males with COPD. More active COPD screening is needed for women of low socioeconomic status, even if they do not smoke.