Comparison of Mitochondrial Respiration in M. triceps brachii and M. vastus lateralis Between Elite Cross-Country Skiers and Physically Active Controls

RationaleThe main purposes of this study were to compare mitochondrial respiration in M. triceps brachii and M. vastus lateralis between elite cross-country (XC) skiers and physically active controls (CON), and to explore the associations between mitochondrial respiration in these muscles and peak oxygen uptake (V˙O2peak) in arm- and leg-dominant exercise modes.MethodsThirteen male elite XC skiers (age: 25 ± 4; peak oxygen uptake (V˙O2peak): 75.5 ± 4.2 mL⋅kg-1⋅min-1) and twelve CON (age: 26 ± 3; V˙O2peak: 57.2 ± 6.4 mL⋅kg-1⋅min-1) had microbiopsies taken from M. vastus lateralis and M. triceps brachii, which were analyzed for various measures of mitochondrial respiration using high-resolution respirometry. Thereafter, all participants tested V˙O2peak in both running (RUN) and upper body poling (UBP).ResultsXC skiers had generally higher mitochondrial respiration in M. triceps brachii compared to CON (P < 0.001), whereas no significant group-differences in mitochondrial respiration in M. vastus lateralis were revealed. XC skiers had higher mitochondrial respiration in M. triceps brachii compared to M. vastus lateralis (P = 0.005–0.058), whereas in CON, most mitochondrial respiration measures were higher in M. vastus lateralis than in M. triceps brachii (P < 0.01). When all athletes were pooled, there was a strong positive correlation between V˙O2peak in UBP and mitochondrial respiration in M. triceps brachii on several measures (P < 0.01), whereas no correlation was found for RUN.ConclusionThe higher mitochondrial respiration found in M. triceps brachii compared to M. vastus lateralis among our elite XC skiers demonstrates the potential for the arm muscles to adapt to aerobic endurance training. The opposite pattern found in CON, clearly showed lower mitochondrial respiration in M. triceps brachii compared to XC skiers, whereas respiration in M. vastus lateralis did not differ between groups. The strong positive correlation between mitochondrial respiration in M. triceps brachii and V˙O2peak in UBP indicate that arm muscles’ respiratory function may be a limiting factor for V˙O2peak in arm-dominant exercise modes

Continuous positive airway pressure in cluster headache: A randomized, placebo-controlled, triple-blind, crossover study

Background - Oxygen inhalation aborts cluster headache attacks, and case reports show the effect of continuous positive airway pressure. The aim of this study was to investigate the prophylactic effect of continuous positive airway pressure in chronic cluster headache. Methods - This was a randomized placebo-controlled triple-blind crossover study using active and sham continuous positive airway pressure treatment for chronic cluster headache. Patients entered a one month’s baseline period before randomly being assigned to two months’ active continuous positive airway pressure treatment followed by a four weeks’ washout period and two months’ sham continuous positive airway pressure or vice versa. Primary outcome measure was number of cluster headache attacks/week. Results - Of the 30 included participants (12 males, median age 49.5 years, min-max 20–66 years), 25 completed both treatment/sham cycles (two discontinued, three lost to follow-up). The median number of cluster headache attacks per week was reduced from 8.25 (0.75–89.75) attacks to 6.25 (0–56.00) attacks for active continuous positive airway pressure and to 7.50 (0.50–43.75) attacks for sham continuous positive airway pressure, but there was no difference in active versus sham (p = 0.904). One patient had a serious adverse event during active treatment, none occurred during sham treatment. Conclusions - Continuous positive airway pressure treatment did not reduce the number of cluster headache attacks compared to sham treatment in chronic cluster headache patients

Exercise Training Reverses Extrapulmonary Impairments in Smoke-exposed Mice

Purpose: Cigarette smoking is the main risk factor for chronic obstructive pulmonary disease and emphysema. However, evidence on the extrapulmonary effects of smoke exposure that precede lung impairments remains unclear at present, as are data on nonpharmacological treatments such as exercise training. Methods: Three groups of mice, including control (n = 10), smoking (n = 10), and smoking with 6 wk of high-intensity interval treadmill running (n = 11), were exposed to 20 wk of fresh air or whole-body cigarette smoke. Exercise capacity (peak oxygen uptake) and lung destruction (histology) were subsequently measured, whereas the heart, peripheral endothelium (aorta), and respiratory (diaphragm) and limb (extensor digitorum longus and soleus) skeletal muscles were assessed for in vivo and in vitro function, in situ mitochondrial respiration, and molecular alterations. Results: Smoking reduced body weight by 26% (P 0.05). Smoking impaired exercise capacity by 15% while inducing right ventricular dysfunction by ~20%, endothelial dysfunction by ~20%, and diaphragm muscle weakness by ~15% (all P < 0.05), but these were either attenuated or reversed by exercise training (P < 0.05). Compared with controls, smoking mice had normal limb muscle and mitochondrial function (cardiac and skeletal muscle fibers); however, diaphragm measures of oxidative stress and protein degradation were increased by 111% and 65%, respectively (P < 0.05), but these were attenuated by exercise training (P < 0.05). Conclusions: Prolonged cigarette smoking reduced exercise capacity concomitant with functional impairments to the heart, peripheral endothelium, and respiratory muscle that preceded the development of overt emphysema. However, high-intensity exercise training was able to reverse these smoke-induced extrapulmonary impairments

Comparison of Mitochondrial Respiration in M. triceps brachii and M. vastus lateralis Between Elite Cross-Country Skiers and Physically Active Controls

Rationale: The main purposes of this study were to compare mitochondrial respiration in M. triceps brachii and M. vastus lateralis between elite cross-country (XC) skiers and physically active controls (CON), and to explore the associations between mitochondrial respiration in these muscles and peak oxygen uptake (V˙ O2peak) in arm- and leg-dominant exercise modes. Methods: Thirteen male elite XC skiers (age: 25 ± 4; peak oxygen uptake (V˙ O2peak): 75.5 ± 4.2 mL⋅kg-1⋅min-1) and twelve CON (age: 26 ± 3; V˙O2peak: 57.2 ± 6.4 mL⋅kg-1⋅min-1) had microbiopsies taken from M. vastus lateralis and M. triceps brachii, which were analyzed for various measures of mitochondrial respiration using high-resolution respirometry. Thereafter, all participants tested V˙ O2peak in both running (RUN) and upper body poling (UBP). Results: XC skiers had generally higher mitochondrial respiration in M. triceps brachii compared to CON (P < 0.001), whereas no significant group-differences in mitochondrial respiration in M. vastus lateralis were revealed. XC skiers had higher mitochondrial respiration in M. triceps brachii compared to M. vastus lateralis (P = 0.005–0.058), whereas in CON, most mitochondrial respiration measures were higher in M. vastus lateralis than in M. triceps brachii (P < 0.01). When all athletes were pooled, there was a strong positive correlation between V˙ O2peak in UBP and mitochondrial respiration in M. triceps brachii on several measures (P < 0.01), whereas no correlation was found for RUN. Conclusion: The higher mitochondrial respiration found in M. triceps brachii compared to M. vastus lateralis among our elite XC skiers demonstrates the potential for the arm muscles to adapt to aerobic endurance training. The opposite pattern found in CON, clearly showed lower mitochondrial respiration in M. triceps brachii compared to XC skiers, whereas respiration in M. vastus lateralis did not differ between groups. The strong positive correlation between mitochondrial respiration in M. triceps brachii and V˙ O2peak in UBP indicate that arm muscles’ respiratory function may be a limiting factor for V˙O2peak in arm-dominant exercise modes

High-intensity interval training and pulmonary hemodynamics in COPD with hypoxemia

Background Exercise is recommended for all patients with COPD. Evidence for its benefit is considerably weaker in the more severe stages of the disease. The aim of this study was to investigate whether high-intensity interval training could improve exercise capacity, pulmonary hemodynamics and cardiac function in patients with severe COPD and hypoxemia. Methods Stable patients with COPD GOLD stage III or IV and hypoxemia were included. They underwent extensive cardiopulmonary testing including right heart catheterization, lung function tests, echocardiography and 6-minute walk test before and after completion of 10 weeks of high-intensity interval training performed with supplemental oxygen. Primary endpoint was change in pulmonary artery pressure measured by right heart catheterization. Results Ten patients with very severe airflow obstruction, mean FEV1 28.7% predicted and mean FEV1/VC 0.39 completed the exercise programme. Pulmonary artery pressure remained unchanged following the intervention (26,3 mmHg vs. 25,8 mmHg at baseline, p 0.673). Six-minute walk distance improved by a mean of44.8 m (p 0.010), which is also clinically significant. We found marginally improved left ventricular ejection fraction on echocardiography (54.6% vs 59.5%, p 0.046). Conclusion High-intensity interval training significantly improved exercise capacity while pulmonary hemodynamics remained unchanged. The improvement may therefore be due to mechanisms other than altered pulmonary artery pressure. The increase in ejection fraction is of uncertain clinical significance. The low number of patients precludes firm conclusions

Learning Realistic Patterns from Visually Unrealistic Stimuli: Generalization and Data Anonymization

Good training data is a prerequisite to develop useful Machine Learning applications. However, in many domains existing data sets cannot be shared due to privacy regulations (e.g., from medical studies). This work investigates a simple yet unconventional approach for anonymized data synthesis to enable third parties to benefit from such anonymized data. We explore the feasibility of learning implicitly from visually unrealistic, task-relevant stimuli, which are synthesized by exciting the neurons of a trained deep neural network. As such, neuronal excitation can be used to generate synthetic stimuli. The stimuli data is used to train new classification models. Furthermore, we extend this framework to inhibit representations that are associated with specific individuals. We use sleep monitoring data from both an open and a large closed clinical study, and Electroencephalogram sleep stage classification data, to evaluate whether (1) end-users can create and successfully use customized classification models, and (2) the identity of participants in the study is protected. Extensive comparative empirical investigation shows that different algorithms trained on the stimuli are able to generalize successfully on the same task as the original model. Architectural and algorithmic similarity between new and original models play an important role in performance. For similar architectures, the performance is close to that of using the original data (e.g., Accuracy difference of 0.56%-3.82%, Kappa coefficient difference of 0.02-0.08). Further experiments show that the stimuli can provide state-ofthe-art resilience against adversarial association and membership inference attacks

Prevalence, risk factors, and type of sleep apnea in patients with paroxysmal atrial fibrillation

Background Recent studies have suggested an association between sleep apnea (SA) and atrial fibrillation (AF). We aimed to study the prevalence, characteristics, risk factors and type of sleep apnea (SA) in ablation candidates with paroxysmal AF. Methods/Results We prospectively studied 579 patients with paroxysmal AF, including 157 women (27.1%) and 422 men (72.9%). Mean age was 59.9 ± 9.6 years and mean body mass index (BMI) 28.5 ± 4.5 kg/m2. SA was diagnosed using polygraphy for two nights at home. The Epworth Sleepiness Scale (ESS), STOP-Bang Questionnaire, and Berlin Questionnaire (BQ) assessed the degree of SA symptoms. A total of 479 (82.7%) patients had an apnea-hypopnea index (AHI) ≥ 5, whereas moderate-severe SA (AHI ≥ 15) was diagnosed in 244 patients (42.1%). The type of SA was predominantly obstructive, with a median AHI of 12.1 (6.7–20.6) (range 0.4–85.8). The median central apnea index was 0.3 (0.1–0.7). AHI increased with age, BMI, waist and neck circumference, body and visceral fat. Using the Atrial Fibrillation Severity Scale and the SF-36, patients with more severe SA had a higher AF burden, severity and symptom score and a lower Physical-Component Summary score. Age, male gender, BMI, duration of AF, and habitual snoring were independent risk factors in multivariate analysis (AHI ≥ 15). We found no association between ESS and AHI (R2 = 0.003, p = 0.367). Conclusions In our AF population, SA was highly prevalent and predominantly obstructive. The high prevalence of SA detected in this study may indicate that SA is under-recognized in patients with AF. None of the screening questionnaires predicted SA reliably

Comparing manual and automatic scoring of sleep monitoring data from portable polygraphy

We used sleep monitoring data from a study that investigated the prevalence, characteristics, risk factors and type of sleep apnea (SA) in 579 patients with paroxysmal atrial fibrillation. Most patients were screened for two nights, resulting in 1,043 sleep recordings that each contained data from one night. SA was diagnosed using the Nox T3 portable sleep monitor. An experienced sleep specialist scored the recordings manually using Noxturnal software. A total of 157 women (27%) and 422 men (73%) were examined; 477 (82.7%) had an apnea–hypopnea index (AHI) ≥ 5/hr, whereas moderate to severe SA (AHI ≥ 15/hr) was diagnosed in 243 patients (42.1%). The AHI derived from automatic and manual scoring showed a good agreement (Pearson's r coefficient of 0.96). The median difference in AHI was very small (i.e., 0.72 [mean difference, 1.06]), but was statistically significant (p < .0001). Automatic scoring classified sleep recordings with more than 90% accuracy into SA categories of mild (AHI ≥ 5/hr), moderate (AHI ≥ 15/hr) and severe (AHI ≥ 30/hr). We found a minor (11%–21%) mis‐estimation of the number of recordings right above and below the boundary separating mild and moderate SA. The accuracy of automatic scoring differed from recording to recording, especially regarding the sensitivity of detecting disrupted breathing events. We found low to moderate agreement for the duration of disrupted breathing events (r = .53), for which the automatic scoring led to a statistically significant overestimation by 5.22 s (p < .0001)

Comparing manual and automatic scoring of sleep monitoring data from portable polygraphy

We used sleep monitoring data from a study that investigated the prevalence, characteristics, risk factors and type of sleep apnea (SA) in 579 patients with paroxysmal atrial fibrillation. Most patients were screened for two nights, resulting in 1,043 sleep recordings that each contained data from one night. SA was diagnosed using the Nox T3 portable sleep monitor. An experienced sleep specialist scored the recordings manually using Noxturnal software. A total of 157 women (27%) and 422 men (73%) were examined; 477 (82.7%) had an apnea–hypopnea index (AHI) ≥ 5/hr, whereas moderate to severe SA (AHI ≥ 15/hr) was diagnosed in 243 patients (42.1%). The AHI derived from automatic and manual scoring showed a good agreement (Pearson's r coefficient of 0.96). The median difference in AHI was very small (i.e., 0.72 [mean difference, 1.06]), but was statistically significant (p < .0001). Automatic scoring classified sleep recordings with more than 90% accuracy into SA categories of mild (AHI ≥ 5/hr), moderate (AHI ≥ 15/hr) and severe (AHI ≥ 30/hr). We found a minor (11%–21%) mis‐estimation of the number of recordings right above and below the boundary separating mild and moderate SA. The accuracy of automatic scoring differed from recording to recording, especially regarding the sensitivity of detecting disrupted breathing events. We found low to moderate agreement for the duration of disrupted breathing events (r = .53), for which the automatic scoring led to a statistically significant overestimation by 5.22 s (p < .0001)