A simple clinical risk score (ABCDMP) for predicting mortality in patients with AECOPD and cardiovascular diseases.

BACKGROUND: The morbidity and mortality among hospital inpatients with AECOPD and CVDs remains unacceptably high. Currently, no risk score for predicting mortality has been specifically developed in patients with AECOPD and CVDs. We therefore aimed to derive and validate a simple clinical risk score to assess individuals' risk of poor prognosis. STUDY DESIGN AND METHODS: We evaluated inpatients with AECOPD and CVDs in a prospective, noninterventional, multicenter cohort study. We used multivariable logistic regression analysis to identify the independent prognostic risk factors and created a risk score model according to patients' data from a derivation cohort. Discrimination was evaluated by the area under the receiver-operating characteristic curve (AUC), and calibration was assessed by the Hosmer-Lemeshow goodness-of-fit test. The model was validated and compared with the BAP-65, CURB-65, DECAF and NIVO models in a validation cohort. RESULTS: We derived a combined risk score, the ABCDMP score, that included the following variables: age > 75 years, BUN > 7 mmol/L, consolidation, diastolic blood pressure ≤ 60 mmHg, mental status altered, and pulse > 109 beats/min. Discrimination (AUC 0.847, 95% CI, 0.805-0.890) and calibration (Hosmer‒Lemeshow statistic, P = 0.142) were good in the derivation cohort and similar in the validation cohort (AUC 0.811, 95% CI, 0.755-0.868). The ABCDMP score had significantly better predictivity for in-hospital mortality than the BAP-65, CURB-65, DECAF, and NIVO scores (all P < 0.001). Additionally, the new score also had moderate predictive performance for 3-year mortality and can be used to stratify patients into different management groups. CONCLUSIONS: The ABCDMP risk score could help predict mortality in AECOPD and CVDs patients and guide further clinical research on risk-based treatment. CLINICAL TRIAL REGISTRATION: Chinese Clinical Trail Registry NO.:ChiCTR2100044625; URL: http://www.chictr.org.cn/showproj.aspx?proj=121626 .

Characteristics, treatments, in-hospital and long-term outcomes among inpatients with acute exacerbation of chronic obstructive pulmonary disease in China: sex differences in a large cohort study.

BACKGROUND: Data related to the characteristics, treatments and clinical outcomes of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients in China are limited, and sex differences are still a neglected topic. METHODS: The patients hospitalized for AECOPD were prospectively enrolled from ten medical centers in China between September 2017 and July 2021. Patients from some centers received follow-up for 3 years. Data regarding the characteristics, treatments and in-hospital and long-term clinical outcomes from male and female AECOPD patients included in the cohort were analyzed and compared. RESULTS: In total, 14,007 patients with AECOPD were included in the study, and 11,020 (78.7%) were males. Compared with males, female patients were older (74.02 ± 10.79 vs. 71.86 ± 10.23 years, P < 0.001), and had more comorbidities (2.22 ± 1.64 vs. 1.73 ± 1.56, P < 0.001), a higher frequency of altered mental status (5.0% vs. 2.9%, P < 0.001), lower diastolic blood pressure (78.04 ± 12.96 vs. 79.04 ± 12.47 mmHg, P < 0.001). In addition, there were also significant sex differences in a range of laboratory and radiographic findings. Females were more likely to receive antibiotics, high levels of respiratory support and ICU admission than males. The in-hospital and 3-year mortality were not significantly different between males and females (1.4% vs. 1.5%, P = 0.711; 35.3% vs. 31.4%, P = 0.058), while female smokers with AECOPD had higher in-hospital mortality than male smokers (3.3% vs. 1.2%, P = 0.002) and male smokers exhibited a trend toward higher 3-year mortality compared to female smokers (40.7% vs. 33.1%, P = 0.146). CONCLUSIONS: In AECOPD inpatients, females and males had similar in-hospital and long-term survival despite some sex differences in clinical characteristics and treatments, but female smokers had significantly worse in-hospital outcomes than male smokers. CLINICAL TRIAL REGISTRATION: Retrospectively registered, registration number is ChiCTR2100044625, date of registration 21/03/2021. URL: http://www.chictr.org.cn/showproj.aspx?proj=121626 .

Risk factors of in-hospital mortality and discriminating capacity of NIVO score in exacerbations of COPD requiring noninvasive ventilation.

BACKGROUND: Noninvasive mechanical ventilation (NIV) is recommended as the initial mode of ventilation to treat acute respiratory failure in patients with AECOPD. The Noninvasive Ventilation Outcomes (NIVO) score has been proposed to evaluate the prognosis in patients with AECOPD requiring assisted NIV. However, it is not validated in Chinese patients. METHODS: We used data from the MAGNET AECOPD Registry study, which is a prospective, noninterventional, multicenter, real-world study conducted between September 2017 and July 2021 in China. Data for the potential risk factors of mortality were collected and the NIVO score was calculated, and the in-hospital mortality was evaluated using the NIVO risk score. RESULTS: A total of 1164 patients were included in the study, and 57 patients (4.9%) died during their hospital stay. Multiple logistic regression analysis revealed that age ≥75 years, DBP <60 mmHg, Glasgow Coma Scale ≤14, anemia and BUN >7 mmol/L were independent predictors of in-hospital mortality. The in-hospital mortality was associated with an increase in the risk level of NIVO score and the difference was statistically significant (p < .001). The NIVO risk score showed an acceptable accuracy for predicting the in-hospital mortality in AECOPD requiring assisted NIV (AUC: 0.657, 95% CI: 0.584-0.729, p < .001). CONCLUSION: Our findings identified predictors of mortality in patients with AECOPD receiving NIV, providing useful information to identify severe patients and guide the management of AECOPD. The NIVO score showed an acceptable predictive value for AECOPD receiving NIV in Chinese patients, and additional studies are needed to develop and validate predictive scores based on specific populations.

Treatment of obstructive sleep apnea with a simple CPAP device.

PURPOSE: CPAP is the "gold standard" treatment for obstructive sleep apnea (OSA). Current CPAP models have developed additional functions including automatic CPAP and pressure relief. However, CPAP adherence has not improved over the last three decades. Many patients in low-income countries cannot afford these CPAP devices. A novel simple CPAP device with a fixed pressure without pressure controller was developed. METHODS: Manual CPAP pressure titration was performed in 127 patients with OSA. Six patients with a titration pressure higher than 11 cmH2O and 14 patients who could not tolerate CPAP were excluded, leaving 107 participating in the following 2 studies. In study one, 54 of 107 patients were treated by both conventional fixed CPAP and simple CPAP in random order. In the second study, another 53 patients were treated by both autoCPAP in automatic function and simple CPAP in random order. Simple CPAP was fixed at 10 cmH2O, 8 cmH2O, and 6 cmH2O for patients whose titration pressure was between 9-10, 7-8, and ≤ 6 cmH2O, respectively. Conventional fixed CPAP device was set exactly the same as manual titration pressure. RESULTS: All patients whose manual titration pressure ≤ 10 cmH2O were effectively treated by simple CPAP (AHI 40.7 ± 2.3 events/h before vs 2.5 ± 0.3 events/h after, p < 0.001). Patients expressed similar preferences for simple CPAP, autoCPAP, and conventional fixed CPAP (p > 0.05). CONCLUSIONS: We conclude that a novel simple CPAP is an alternative treatment for most patients with OSA, which may widen access to CPAP therapy in the developing countries because of its low cost.

Polyene Carboxylic Acids from a Streptomyces sp. Isolated from Tibet Soil.

Six new polyene carboxylic acids named serpentemycins E-J (1-6), together with three known analogs (7-9), were isolated from the fermentation medium of Streptomyces sp. TB060207, which was isolated from arid soil collected from Tibet, China. The structures of the new compounds were elucidated mainly on the basis of HR-ESI-MS and NMR spectroscopic analyses. The inhibitory activities of compounds 1-9 against NO production in LPS-activated RAW264.7 cells were evaluated. Compound 9 has an inhibition rate of 87.09% to 60.53% at concentrations ranging from 5.0 to 40.0 µM.

Protein O-mannosylation affects protein secretion, cell wall integrity and morphogenesis in Trichoderma reesei.

Protein O-mannosyltransferases (PMTs) initiate O-mannosylation of proteins in the ER. Trichoderma reesei strains displayed a single representative of each PMT subfamily, Trpmt1, Trpmt2 and Trpmt4. In this work, two knockout strains ΔTrpmt1and ΔTrpmt4were obtained. Both mutants showed retarded growth, defective cell walls, reduced conidiation and decreased protein secretion. Additionally, the ΔTrpmt1strain displayed a thermosensitive growth phenotype, while the ΔTrpmt4 strain showed abnormal polarity. Meanwhile, OETrpmt2 strain, in which the Trpmt2 was over-expressed, exhibited increased conidiation, enhanced protein secretion and abnormal polarity. Using a lectin enrichment method and MS/MS analysis, 173 O-glycoproteins, 295 O-glycopeptides and 649 O-mannosylation sites were identified as the targets of PMTs in T. reesei. These identified O-mannoproteins are involved in various physiological processes such as protein folding, sorting, transport, quality control and secretion, as well as cell wall integrity and polarity. By comparing proteins identified in the mutants and its parent strain, the potential specific protein substrates of PMTs were identified. Based on our results, TrPMT1 is specifically involved inO-mannosylation of intracellular soluble proteins and secreted proteins, specially glycosidases. TrPMT2 is involved inO-mannosylation of secreted proteins and GPI-anchor proteins, and TrPMT4 mainly modifies multiple transmembrane proteins. The TrPMT1-TrPMT4 complex is responsible for O-mannosylation of proteins involved in cell wall integrity. Overexpression of TrPMT2 enhances protein secretion, which might be a new strategy to improve expression efficiency in T. reesei.

Genetical and O-glycoproteomic analyses reveal the roles of three protein O-mannosyltransferases in phytopathogen Fusarium oxysporum f.sp. cucumerinum.

Protein O-mannosyltransferases (PMTs) have been identified in fungi but not in plants and nematodes, which makes PMTs become attractive targets for developing a new strategy against phytopathogens. Three PMTs have been identified in Fusarium oxysporum, a fungal pathogen that causes vascular wilt in a broad range of economical crops. By deletion or suppression of the pmt genes, we showed that all mutants displayed retarded growth, reduced conidiation, cell wall defects, ER stress and attenuated virulence in F. oxysporum f.sp. cucumerinum. In addition, the Δpmt1 exhibited reduced thermotolerance, while the Δpmt4 and the pmt2 conditional mutant exhibited abnormal polarized growth. Comparative glycoproteome analysis of these pmt mutants revealed that PMTs preferentially modified random coils with flanking regions rich in Ser, Thr, Ala, Glu, Asp and Lys at the stem region of membrane proteins, the N-terminal region close to signal peptide of secreted proteins, or surface of soluble proteins. PMT1 specifically acted on nuclear proteins and proteins that are responsible for protein folding, which might contribute to thermotolerance. PMT4 specifically acted on the membrane and soluble proteins in secretory pathways, especially the GPI anchoring pathway, which might contribute to synthesis and transportation of GPI anchored proteins and thus polarized growth. PMT2 was responsible for modification of proteins that are required for protein folding and cell wall synthesis, which might make PMT2 essential. Our results gave an insight to understanding of the roles of each O-mannosyltransferase in F. oxysporum f.sp. cucumerinum and provide a new perspective to prevent Fusarium wilt.

CPAP for Prevention of Cardiovascular Events in Obstructive Sleep Apnea.

BACKGROUND: Obstructive sleep apnea is associated with an increased risk of cardiovascular events; whether treatment with continuous positive airway pressure (CPAP) prevents major cardiovascular events is uncertain. METHODS: After a 1-week run-in period during which the participants used sham CPAP, we randomly assigned 2717 eligible adults between 45 and 75 years of age who had moderate-to-severe obstructive sleep apnea and coronary or cerebrovascular disease to receive CPAP treatment plus usual care (CPAP group) or usual care alone (usual-care group). The primary composite end point was death from cardiovascular causes, myocardial infarction, stroke, or hospitalization for unstable angina, heart failure, or transient ischemic attack. Secondary end points included other cardiovascular outcomes, health-related quality of life, snoring symptoms, daytime sleepiness, and mood. RESULTS: Most of the participants were men who had moderate-to-severe obstructive sleep apnea and minimal sleepiness. In the CPAP group, the mean duration of adherence to CPAP therapy was 3.3 hours per night, and the mean apnea-hypopnea index (the number of apnea or hypopnea events per hour of recording) decreased from 29.0 events per hour at baseline to 3.7 events per hour during follow-up. After a mean follow-up of 3.7 years, a primary end-point event had occurred in 229 participants in the CPAP group (17.0%) and in 207 participants in the usual-care group (15.4%) (hazard ratio with CPAP, 1.10; 95% confidence interval, 0.91 to 1.32; P=0.34). No significant effect on any individual or other composite cardiovascular end point was observed. CPAP significantly reduced snoring and daytime sleepiness and improved health-related quality of life and mood. CONCLUSIONS: Therapy with CPAP plus usual care, as compared with usual care alone, did not prevent cardiovascular events in patients with moderate-to-severe obstructive sleep apnea and established cardiovascular disease. (Funded by the National Health and Medical Research Council of Australia and others; SAVE ClinicalTrials.gov number, NCT00738179 ; Australian New Zealand Clinical Trials Registry number, ACTRN12608000409370 .).

ERS statement on respiratory muscle testing at rest and during exercise.

Assessing respiratory mechanics and muscle function is critical for both clinical practice and research purposes. Several methodological developments over the past two decades have enhanced our understanding of respiratory muscle function and responses to interventions across the spectrum of health and disease. They are especially useful in diagnosing, phenotyping and assessing treatment efficacy in patients with respiratory symptoms and neuromuscular diseases. Considerable research has been undertaken over the past 17 years, since the publication of the previous American Thoracic Society (ATS)/European Respiratory Society (ERS) statement on respiratory muscle testing in 2002. Key advances have been made in the field of mechanics of breathing, respiratory muscle neurophysiology (electromyography, electroencephalography and transcranial magnetic stimulation) and on respiratory muscle imaging (ultrasound, optoelectronic plethysmography and structured light plethysmography). Accordingly, this ERS task force reviewed the field of respiratory muscle testing in health and disease, with particular reference to data obtained since the previous ATS/ERS statement. It summarises the most recent scientific and methodological developments regarding respiratory mechanics and respiratory muscle assessment by addressing the validity, precision, reproducibility, prognostic value and responsiveness to interventions of various methods. A particular emphasis is placed on assessment during exercise, which is a useful condition to stress the respiratory system.

The acute effect of continuous positive airway pressure titration on blood pressure in awake overweight/obese patients with obstructive sleep apnoea.

OBJECTIVES: Continuous positive airway pressure (CPAP) improves upper airway obstruction in patients with obstructive sleep apnoea (OSA), who often are overweight-obese. Although it is thought that CPAP improves long-term blood pressure control (BP), the impact of acute and short-term CPAP use on the cardiovascular system in obese patients has not been described in detail. METHODS: Obese patients (body mass index, BMI > 25 kg/m2) with OSA were studied awake, supine during incremental CPAP titration (4-20 cmH2O, +2 cmH2O/3 mins). BP was measured continuously with a beat-to-beat BP monitor (Ohmeda 2300, Finapres Medical Systems, Amsterdam/NL), BP variability (BPV) was calculated as the standard deviation of BP at each CPAP level, the 95% confidence interval (95%CI) was calculated and changes in BP and BPV were reported. RESULTS: 15 patients (12 male, 48 ± 10) years, BMI 38.9 ± 5.8 kg/m2) were studied; the baseline BP was 131.0 ± 10.2/85.1 ± 9.1 mmHg. BP and BPV increased linearly with CPAP titration (systolic BP r = 0.960, p < .001; diastolic BP r = 0.961, p < .001; systolic BPV r = 0.662, p = .026; diastolic BPV r = 0.886, p < .001). The systolic BP increased by +17% (+23.15 (7.9, 38.4) mmHg; p = .011) and the diastolic BP by +23% (+18.27 (2.33, 34.21) mmHg; p = .009), when titrating CPAP to 20 cmH2O. Systolic BPV increased by +96% (+5.10 (0.67, 9.53) mmHg; p < .001) and was maximal at 14 cmH2O, and diastolic BPV by +97% (+3.02 (0.26, 5.78) mmHg; p < .001) at 16 cmH2O. CONCLUSION: Short-term incremental CPAP leads to significant increases in BP and BPV in obese patients with OSA while awake. Careful titration of pressures is required to minimise the risk of nocturnal awakenings while improving BP control.

Systematic Analysis of Lysine Acetylation in the Halophilic Archaeon Haloferax mediterranei.

Lysine acetylation is a reversible and highly regulated post-translational modification that plays a critical role in regulating many aspects of cellular processes, both in bacteria and in eukaryotes. However, this modification has not been systematically studied in archaea. Herein, we report the lysine acetylome of a model haloarchaeon, Haloferax mediterranei. Using immunoaffinity enrichment and LC-MS/MS analysis, we identified 1017 acetylation sites in 643 proteins, accounting for 17.3% of the total proteins in this haloarchaeon. Bioinformatics analysis indicated that lysine acetylation mainly distributes in cytoplasm (94%) and participates in protein biosynthesis and carbon metabolism. Specifically, the acetylation of key enzymes in PHBV biosynthesis further suggested that acetylation plays a key role in the energy and carbon storage. In addition, a survey of the acetylome revealed a universal rule in acetylated motifs: a positively charged residue (K, R, or H) located downstream of acetylated lysine at the positions +1, +2, or +3. Interestingly, we identified acetylation in several replication initiation proteins Cdc6; mutation on the acetylated site of Cdc6A destroyed the Autonomous Replication Sequence (ARS) activity of its adjacent origin oriC1. Our study indicates that lysine acetylation is an abundant modification in H. mediterranei, and plays key roles in the processes of replication, protein biosynthesis, central metabolism, and carbon storage. This acetylome of H. mediterranei provides opportunities to explore the physiological role of acetylation in halophilic archaea.

Coexistence of OSA may compensate for sleep related reduction in neural respiratory drive in patients with COPD.

BACKGROUND: The mechanisms underlying sleep-related hypoventilation in patients with coexisting COPD and obstructive sleep apnoea (OSA), an overlap syndrome, are incompletely understood. We compared neural respiratory drive expressed as diaphragm electromyogram (EMGdi) and ventilation during stage 2 sleep in patients with COPD alone and patients with overlap syndrome. METHODS: EMGdi and airflow were recorded during full polysomnography in 14 healthy subjects, 14 patients with OSA and 39 consecutive patients with COPD. The ratio of tidal volume to EMGdi was measured to indirectly assess upper airway resistance. RESULTS: Thirty-five patients with COPD, 12 healthy subjects and 14 patients with OSA completed the study. Of 35 patients with COPD, 19 had COPD alone (FEV1 38.5%±16.3%) whereas 16 had an overlap syndrome (FEV1 47.5±16.2%, AHI 20.5±14.1 events/hour). Ventilation (VE) was lower during stage 2 sleep than wakefulness in both patients with COPD alone (8.6±2.0 to 6.5±1.5 L/min, p<0.001) and those with overlap syndrome (8.3±2.0 to 6.1±1.8 L/min). Neural respiratory drive from wakefulness to sleep decreased significantly for patients with COPD alone (29.5±13.3% to 23.0±8.9% of maximal, p<0.01) but it changed little in those with overlap syndrome. The ratio of tidal volume to EMGdi was unchanged from wakefulness to sleep in patients with COPD alone and healthy subjects but was significantly reduced in patients with OSA or overlap syndrome (p<0.05). CONCLUSIONS: Stage 2 sleep-related hypoventilation in COPD alone is due to reduction of neural respiratory drive, but in overlap syndrome it is due to increased upper airway resistance.

Insight into Enzymatic Degradation of Corn, Wheat, and Soybean Cell Wall Cellulose Using Quantitative Secretome Analysis of Aspergillus fumigatus.

Lignocelluloses contained in animal forage cannot be digested by pigs or poultry with 100% efficiency. On contrary, Aspergillus fumigatus, a saprophytic filamentous fungus, is known to harbor 263 glycoside hydrolase encoding genes, suggesting that A. fumigatus is an efficient lignocellulose degrader. Hence the present study uses corn, wheat, or soybean as a sole carbon source to culture A. fumigatus under animal physiological condition to understand how cellulolytic enzymes work together to achieve an efficient degradation of lignocellulose. Our results showed that A. fumigatus produced different sets of enzymes to degrade lignocelluloses derived from corn, wheat, or soybean cell wall. In addition, the cellulolytic enzymes produced by A. fumigatus were stable under acidic condition or at higher temperatures. Using isobaric tags for a relative and absolute quantification (iTRAQ) approach, a total of ∼600 extracellular proteins were identified and quantified, in which ∼50 proteins were involved in lignocellulolysis, including cellulases, hemicellulases, lignin-degrading enzymes, and some hypothetical proteins. Data are available via ProteomeXchange with identifier PXD004670. On the basis of quantitative iTRAQ results, 14 genes were selected for further confirmation by RT-PCR. Taken together, our results indicated that the expression and regulation of lignocellulolytic proteins in the secretome of A. fumigatus were dependent on both nature and complexity of cellulose, thus suggesting that a different enzyme system is required for degradation of different lignocelluloses derived from plant cells. Although A. fumigatus is a pathogenic fungus and cannot be directly used as an enzyme source, as an efficient lignocellulose degrader its strategy to synergistically degrade various lignocelluloses with different enzymes can be used to design enzyme combination for optimal digestion and absorption of corn, wheat, or soybean that are used as forage of pig and poultry.

Rice Plasma Membrane Proteomics Reveals Magnaporthe oryzae Promotes Susceptibility by Sequential Activation of Host Hormone Signaling Pathways.

Plant plasma membrane (PM) plays important roles in immune response. Here, we utilized quantitative mass spectrometry to explore rice PM protein composition and dynamic changes during Magnaporthe oryzae infection. We report, thus far, the largest rice PM proteome dataset with 3,906 identified proteins, among which 484 proteins were differentially expressed after M. oryzae infection. One third of the identified proteins are predicted to have at least one transmembrane domain. Half of the identified proteins are predicted to have binding functions and over one third of the proteins have enzyme-related functions. In addition, Gene Ontology analyses revealed that abscisic acid (ABA) and cytokinin (CK) signaling were sequentially activated after M. oryzae infection in rice. We found that the activation of ABA signaling and the suppression of rice immune response occurred at the early infection stage, while the activation of CK signaling, the upregulation of sugar transporter genes expression, and the nutrient efflux of infected rice cells occurred at later infection stage. Thus, we further propose that M. oryzae activates ABA signaling to repress rice immune signaling for initial invasion and redirects nutrient efflux of infected cells for massive growth at the later infection stage.

Neural respiratory drive and symptoms that limit exercise in chronic obstructive pulmonary disease.

BACKGROUND: Exercise capacity in chronic obstructive pulmonary disease (COPD) is limited by both breathlessness and leg muscle fatigue. Neural respiratory drive, measured as diaphragm electromyogram (EMGdi) activity expressed as a proportion of maximum (EMGdi%max), quantifies the mechanical load on the respiratory muscles and relates closely to breathlessness. We tested the hypothesis that end-exercise EMGdi%max would be higher in patients stopping because of breathlessness than in those limited by leg fatigue. METHODS: EMGdi, ventilation, rate of oxygen consumption (VO2), and ventilatory reserve (ventilation/maximum ventilatory volume ratio [VE/MVV]) were measured continuously in patients with COPD during exhaustive cycle ergometry. EMGdi was measured with a multipair oesophageal catheter passed per-nasally. Differences in physiological variables between groups of patients stopping because of breathlessness, leg fatigue, or both were assessed with one-way ANOVA. FINDINGS: 23 patients were included (median FEV1, 39% of predicted, IQR 30·0-56·8). End-exercise EMGdi%max was significantly higher in patients stopping exercise because of breathlessness (n=12, median EMGdi%max 75·7% [IQR 69·5-77·1]) than in those stopping because of leg fatigue (n=8, 44·1 [39·4-63·3]) or both (n=3, 74·1 [63·6-81·2]) (p=0·02). There were no significant differences between the groups in end-exercise ventilation (breathlessness 25·7 L/min [16·3-32·0] vs leg fatigue 31·5 [20·9-39·6] vs both 22·0 [17·7-35·7]), VO2, (13·4 mL/min per kg [11·6-14·2] vs 12·1 [10·4-14·8] vs 9·4 [9·1-12·4]), or VE/MVV (80·4% [72·6-88·3] vs 57·8 [52·1-92·6] vs 63·9 [34·5-88·9]). INTERPRETATION: These results suggest that patients limited by breathlessness due to ventilatory constraints can be identified as those reaching near-maximum levels of neural respiratory drive during exercise. Measurement of EMGdi%max during exercise could prove useful in identifying patients whose functional performance would be best optimised by improvment in pulmonary mechanics rather than interventions to train peripheral muscle groups. FUNDING: None.

Randomised sham-controlled trial of transcutaneous electrical stimulation in obstructive sleep apnoea.

INTRODUCTION: Obstructive sleep apnoea (OSA) is characterised by a loss of neuromuscular tone of the upper airway dilator muscles while asleep. This study investigated the effectiveness of transcutaneous electrical stimulation in patients with OSA. PATIENTS AND METHODS: This was a randomised, sham-controlled crossover trial using transcutaneous electrical stimulation of the upper airway dilator muscles in patients with confirmed OSA. Patients were randomly assigned to one night of sham stimulation and one night of active treatment. The primary outcome was the 4% oxygen desaturation index, responders were defined as patients with a reduction >25% in the oxygen desaturation index when compared with sham stimulation and/or with an index <5/hour in the active treatment night. RESULTS: In 36 patients (age mean 50.8 (SD 11.2) years, male/female 30/6, body mass index median 29.6 (IQR 26.9-34.9) kg/m(2), Epworth Sleepiness Scale 10.5 (4.6) points, oxygen desaturation index median 25.7 (16.0-49.1)/hour, apnoea-hypopnoea index median 28.1 (19.0-57.0)/hour) the primary outcome measure improved when comparing sham stimulation (median 26.9 (17.5-39.5)/hour) with active treatment (median 19.5 (11.6-40.0)/hour; p=0.026), a modest reduction of the mean by 4.1 (95% CI -0.6 to 8.9)/hour. Secondary outcome parameters of patients' perception indicated that stimulation was well tolerated. Responders (47.2%) were predominantly from the mild-to-moderate OSA category. In this subgroup, the oxygen desaturation index was reduced by 10.0 (95% CI 3.9 to 16.0)/hour (p<0.001) and the apnoea-hypopnoea index was reduced by 9.1 (95% CI 2.0 to 16.2)/hour (p=0.004). CONCLUSION: Transcutaneous electrical stimulation of the pharyngeal dilators during a single night in patients with OSA improves upper airway obstruction and is well tolerated. TRIAL REGISTRATION NUMBER: NCT01661712.

Thiosulfate transfer mediated by DsrE/TusA homologs from acidothermophilic sulfur-oxidizing archaeon Metallosphaera cuprina.

Conserved clusters of genes encoding DsrE and TusA homologs occur in many archaeal and bacterial sulfur oxidizers. TusA has a well documented function as a sulfurtransferase in tRNA modification and molybdenum cofactor biosynthesis in Escherichia coli, and DsrE is an active site subunit of the DsrEFH complex that is essential for sulfur trafficking in the phototrophic sulfur-oxidizing Allochromatium vinosum. In the acidothermophilic sulfur (S(0))- and tetrathionate (S4O6(2-))-oxidizing Metallosphaera cuprina Ar-4, a dsrE3A-dsrE2B-tusA arrangement is situated immediately between genes encoding dihydrolipoamide dehydrogenase and a heterodisulfide reductase-like complex. In this study, the biochemical features and sulfur transferring abilities of the DsrE2B, DsrE3A, and TusA proteins were investigated. DsrE3A and TusA proved to react with tetrathionate but not with NaSH, glutathione persulfide, polysulfide, thiosulfate, or sulfite. The products were identified as protein-Cys-S-thiosulfonates. DsrE3A was also able to cleave the thiosulfate group from TusA-Cys(18)-S-thiosulfonate. DsrE2B did not react with any of the sulfur compounds tested. DsrE3A and TusA interacted physically with each other and formed a heterocomplex. The cysteine residue (Cys(18)) of TusA is crucial for this interaction. The single cysteine mutants DsrE3A-C(93)S and DsrE3A-C(101)S retained the ability to transfer the thiosulfonate group to TusA. TusA-C(18)S neither reacted with tetrathionate nor was it loaded with thiosulfate with DsrE3A-Cys-S-thiosulfonate as the donor. The transfer of thiosulfate, mediated by a DsrE-like protein and TusA, is unprecedented not only in M. cuprina but also in other sulfur-oxidizing prokaryotes. The results of this study provide new knowledge on oxidative microbial sulfur metabolism.

Identification of the S-layer glycoproteins and their covalently linked glycans in the halophilic archaeon Haloarcula hispanica.

Haloarcula hispanica is one of members of the Halobacteriaceae, which displays particularly low restriction activity and is therefore important as one of the most tractable haloarchaea for archaeal genetic research. Although the Har. hispanica S-layer protein has been reported glycosylated, the S-layer glycoprotein and its glycosylation have not been investigated yet. In this study, the S-layer proteins of Har. hispanica were extracted and characterized. The S-layer was found containing two different glycoproteins which shared highly similar amino acid sequences. The genes coding for these two S-layer glycoproteins were found next to each other in the genome. Moreover, the N- and O-linked glycans were released from these two S-layer glycoproteins for structural determination. Based on the mass spectrometry and nuclear magnetic resonance, the N-glycan was determined as a branched trisaccharide containing a 225 Da residue corresponded to a 2-amino-6-sulfo-2, 6-dideoxy-quinovose, which was the first time that a naturally occurring form of sulfoquinovosamine was identified. Besides, the O-glycan was characterized as a Glcα-1,4-Gal disaccharide by mass spectrometry combined with monosaccharide composition analysis and glycosidase treatment. The determination of the N- and O-glycan structure will be helpful for studying the diverse protein glycosylation pathways in archaea utilizing H. hispanica as a new model.

Neural respiratory drive and breathlessness in COPD.

The aim of this study was to test the hypothesis that neural respiratory drive, measured using diaphragm electromyogram (EMGdi) activity expressed as a percentage of maximum (EMGdi%max), is closely related to breathlessness in chronic obstructive pulmonary disease. We also investigated whether neuroventilatory uncoupling contributes significantly to breathlessness intensity over an awareness of levels of neural respiratory drive alone. EMGdi and ventilation were measured continuously during incremental cycle and treadmill exercise in 12 chronic obstructive pulmonary disease patients (forced expiratory volume in 1 s±sd was 38.7±14.5 % pred). EMGdi was expressed both as EMGdi%max and relative to tidal volume expressed as a percentage of predicted vital capacity to quantify neuroventilatory uncoupling. EMGdi%max was closely related to Borg breathlessness in both cycle (r=0.98, p=0.0001) and treadmill exercise (r=0.94, p=0.005), this relationship being similar to that between neuroventilatory uncoupling and breathlessness (cycling r=0.94, p=0.005; treadmill r=0.91, p=0.01). The relationship between breathlessness and ventilation was poor when expansion of tidal volume became limited. In chronic obstructive pulmonary disease the intensity of exertional breathlessness is closely related to EMGdi%max. These data suggest that breathlessness in chronic obstructive pulmonary disease can be largely explained by an awareness of levels of neural respiratory drive, rather than the degree of neuroventilatory uncoupling. EMGdi%max could provide a useful physiological biomarker for breathlessness in chronic obstructive pulmonary disease.